WO1996023346A1 - Novel soft switched three-phase boost rectifiers and voltage source inverters - Google Patents

Novel soft switched three-phase boost rectifiers and voltage source inverters Download PDF

Info

Publication number
WO1996023346A1
WO1996023346A1 PCT/US1996/001152 US9601152W WO9623346A1 WO 1996023346 A1 WO1996023346 A1 WO 1996023346A1 US 9601152 W US9601152 W US 9601152W WO 9623346 A1 WO9623346 A1 WO 9623346A1
Authority
WO
WIPO (PCT)
Prior art keywords
direct current
auxiliary
switch
rail
current power
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1996/001152
Other languages
French (fr)
Inventor
Fred C. Lee
Yimin Jiang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Virginia Innovation Partnership Corp
Original Assignee
Center for Innovative Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Center for Innovative Technology filed Critical Center for Innovative Technology
Priority to JP52304496A priority Critical patent/JP3207431B2/en
Priority to EP96905251A priority patent/EP0806077A4/en
Publication of WO1996023346A1 publication Critical patent/WO1996023346A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/42—Conversion of DC power input into AC power output without possibility of reversal
    • H02M7/44—Conversion of DC power input into AC power output without possibility of reversal by static converters
    • H02M7/48—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/4826—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode operating from a resonant DC source, i.e. the DC input voltage varies periodically, e.g. resonant DC-link inverters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
    • H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
    • H02M7/06—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
    • H02M7/062—Avoiding or suppressing excessive transient voltages or currents
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
    • H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
    • H02M7/12—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M7/219—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/42—Conversion of DC power input into AC power output without possibility of reversal
    • H02M7/44—Conversion of DC power input into AC power output without possibility of reversal by static converters
    • H02M7/48—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Definitions

  • the present invention generally relates to soft switched three- phase converters and, more particularly, to three-phase rectifiers and inverters having improvements made to the DC rail side of the converter for improving performance, reliability and power factor correction (PFC).
  • PFC power factor correction
  • FIGS. 1 and 2 are examples of prior art converters which offer PFC.
  • Figure 1 is a three-phase boost rectifier ideal for high power applications which offers unity power factor with continuous input currents.
  • three a.c. phases, V a , V b , and V c are passed through a bridge switching network and over a smoothing capacitor C 0 to supply a d.c. load.
  • Figure 2 shows a prior art three-phase voltage source inverter.
  • a d.c. voltage source V ⁇ n is transformed by a bridge switching network into three-phase a.c. currents, i a , i b , and i c .
  • This type of inverter is widely used in motor drives and Uninterrupted Power Supply (UPS) systems.
  • UPS Uninterrupted Power Supply
  • the space-vector based zero-voltage transition technique can only be implemented with high speed digital signal processor and requires many auxiliary components. Additionally, all these techniques are only about zero-voltage switching. Until now, a suitable zero-current switching technique has not been developed.
  • ZVT zero- voltage-transition
  • ZCT zero-current-transition
  • ZCT zero-current-transition
  • ZVT zero-voltage-transition
  • Zero-current-transition as well as Zero-voltage-transition (ZVT) may also be achieved by adding a simple auxiliary network across the DC rail which operates only during the short turn-on or turn-off transients of the bridge switches.
  • ZCT Zero-current-transition
  • ZVT Zero-voltage-transition
  • a simple, inexpensive auxiliary circuit is added to the DC rail of a conventional voltage source inverter shown in Figure 2 to implement either ZVT and ZCT.
  • Figure 1 is a prior art three-phase boost rectifier
  • Figure 2 is a prior art three-phase voltage source inverter
  • Figure 3 is an improved three phase boost rectifier according to the present invention for reducing diode reverse recovery loss
  • Figure 4 is a three phase boost rectifier according to the present invention for achieving ZVT
  • Figure 5 is a computer generated simulation of the operation of the ZVT rectifier shown in Figure 4.
  • Figure 6 is a ZCT three-phase boost rectifier according to the present invention.
  • Figure 7 is a computer generated simulation of the operation of the ZCT rectifier shown in Figure 6;
  • Figure 8 is a ZVT voltage source converter according to the present invention;
  • Figure 9 is a diagram of control waveforms for the ZVT voltage source converter shown in Figure 8 for i a ⁇ 0 and i b > i c >0;
  • Figure 10 is a computer simulation of a the ZVT voltage source inverter shown in Figure 8.
  • Figure 11 is a is a ZCT voltage source inverter according to the present invention.
  • Figure 12 is a diagram of control waveforms for the ZCT voltage source inverter shown in Figure 8 for i a ⁇ 0 and i c > i b >0;
  • Figure 13 is a computer generated simulation of the ZCT operation of the ZCT voltage source inverter shown in Figure 11 ;
  • Figure 14 is a bi-directional ZVT converter according to the present invention.
  • Figure 15 is a bi-directional ZCT converter according to the present invention.
  • FIG. 3 there is shown three-phase boost rectifier according to the present invention.
  • the rectifier is similar to the rectifier shown in Figure 1 having a three-phase input, v a , v b , and v c , and a bridge switching network comprised of six bridge switches, S ap , S an , S bp , S bn , S cp , and S cn , hereinafter collectively referred to as simply S.
  • Each bridge switch S has an anti-parallel diode associated therewith. It is understood that these anti-parallel diodes may be either discrete components or the body diode in the case of an active switch such as a MOSFET.
  • an ultra fast diode D is introduced in the d.c. rail prior to a smoothing capacitor C 0 supplying a d.c. load.
  • the introduction of the ultra-fast diode D alleviates diode reverse recovery experienced by the diodes in the switching bridge as well as facilitates soft-switching.
  • the prior art three-phase boost rectifier shown in Figure 1 at the moment the active switches S (one in each phase) are turned on, any previously conducting anti-parallel diodes will see a high output voltage as:
  • Zero-current-switching techniques can eliminate the turn-off losses of IGBT, GTO, etc. Consequently, if soft ⁇ switching is also employed the switching frequency can be pushed much higher. This give rise to significant savings of filter inductor size and the circuit cost. Referring now to Figure 4, using the DC rail diode D shown in
  • FIG 3 it possible to implement zero-voltage-transition ZVT in by adding only one simple auxiliary network on the DC side.
  • the proposed ZVT three-phase boost rectifier is shown in Figure 4, where the auxiliary network consists of resonant inductor L r , auxiliary switch S aux , and diode D au ..
  • the auxiliary network only operates during the short tum-on transients of the bridge switches. It is preferred that the bridge switches S are synchronized at their tum-on instants so that the auxiliary ZVT network only operates once per switching cycle.
  • the auxiliary switch S a ⁇ lJl is turned on a short period before the tum-on of the bridge switches S. Therefore, a current builds up in inductor L r .
  • a ZCT three-phase boost rectifier having an auxiliary network which consists of resonant inductor L r , resonant capacitor C r , auxiliary switch S aux , and auxiliary diode D au .
  • the auxiliary network is similar to the network shown in Figure 4 with the addition of the resonant capacitor C r .
  • the ZCT network only operates during the short turn-off transients of the bridge switches S. Again, it is preferred that the bridge switches S are synchronized at their turn-off instants so that the auxiliary ZCT network only operates once per switching cycle.
  • the auxiliary switch S aux is turned on for a short period before the turn-off of the bridge switches S.
  • a current builds up in L r as a result of the resonance between L r and C r due to the initial voltage on C r .
  • All of the boost rectifier circuits of the present invention implement the novel DC rail diode D which has been found to naturally provide a six-step PWM operation which, in prior art circuits not having such a diode, requires a more complicated control circuitry.
  • six- step PWM refers to using six optimal bridge voltage vector combinations in a line cycle of 360°, one for each 60°.
  • An optimal bridge voltage vector combination is the zero vector and the two bridge voltage vectors closest to the input voltage vector.
  • the boost inductors are only charged with the input voltage vector (zero-vector), which produces the minimum input current ripple as compared to other PWM schemes which allow the output voltage to participate in charging the boost inductor.
  • ZVT and ZCT can be also implemented in a voltage source inverter by adding an active switch on the DC rail side.
  • Figure 8 there is shown a soft switching ZVT voltage source inverter according to the present invention.
  • 20KHz is hard to attain for hard-switching high power circuits with currently available devices.
  • the inverter shown in Figure 8 the bridge switches are tumed on (i.e by applying gate drive control signals) while the DC rail switch S R is off so that the switches are under zero voltage tum-on condition. Then, the DC rail switch S R is tumed on aided by the ZVT network composed of L r , S aux , and D aux .
  • An example of the operation is demonstrated in Figure 9 for the case of i a ⁇ 0 and i c > i b > 0.
  • the bridge switches S to be tumed on at the beginning of each switching cycle should be S an , S bp , and S cp .
  • a very simple DC rail switch due to the existence of the DC rail switch, a very simple
  • PWM scheme can be used which only operates one bridge switch and the DC rail switch S R . This leaves S an and S bp on all the time and only switching S cp and S R to obtain the output current control. In this way, the DC rail voltage is kept at zero during the freewheeling state at the end of every switching cycle and thus provides the zero- voltage turn-on condition for S cp at the beginning of the next switching cycle.
  • S cp is gated earlier than S R so that it is turned on under zero-voltage condition, which does not change the circuit freewheeling state.
  • the auxiliary switch S au is tumed on to build a current in the resonant inductor L r .
  • the resonant inductor L r resonates with capacitances across the bridge switches and the DC rail switch S R to provide zero-voltage transition for the turn-on of S R at t, .
  • Times t 2 and t 3 are determined by the current control loops.
  • S cp is tumed on any time after S dc is tumed off.
  • FIG 11 there is shown a zero-current- transition (ZCT) voltage source inverter.
  • the operation principle is that the DC rail switch S is tumed off first with the help of the ZCT network composed of L r , C r , D aux , and S aux .
  • the drive signals of the bridge switches are removed after the turn-off of the DC rail switch S so that they are under zero voltage turn-off condition. Hence, no voltage applied on the switches after they are tumed off.
  • Figure 12 which is the same example case used above to explain the ZVT voltage-source-inverter. However, different from the ZVT voltage- source-inverter, the turn-off instants are synchronized.
  • Figure 14 shows a bi-directional ZVT converter which is a hybrid of the boost rectifier shown in Figures 4 and the voltage source inverter shown in Figure 8. It is noted that if the switch S' and switch S auxl are kept open the circuit is identical to the boost rectifier of Figure 4. If, on the other hand, S aux2 is open, the circuit becomes functionally equivalent to the voltage source inverter of Figure 8.
  • Figure 15 shows a bi-directional ZCT voltage source inverter which is a hybrid of the boost rectifier shown in Figures 6 and the voltage source inverter shown in Figure 11. If the switch S' and switch S aux j are kept open the circuit is identical to the boost rectifier of

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)

Abstract

A boost rectifier is provided with an ultra high speed diode (D) in its direct current rail to reduce diode reverse recovery loss with or without implementing a soft switching technique. Full zero-voltage-transition (ZVT) as well as zero-current transition (ZCT) may also be achieved by adding a simple auxiliary network (Lr, Daux, Saux) across the DC rail which operates only during the short turn-on transients of the bridge switches (Sap-Scn). Similarly, a simple, inexpensive auxiliary circuit can be added to the DC rail of a conventional voltage source inverter shown to implement both ZVT and ZCT.

Description

NOVEL SOFT SWITCHED THREE-PHASE BOOST RECTIFIERS AND VOLTAGE SOURCE INVERTERS
DESCRIPTION
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention generally relates to soft switched three- phase converters and, more particularly, to three-phase rectifiers and inverters having improvements made to the DC rail side of the converter for improving performance, reliability and power factor correction (PFC).
Description of the Prior Art
Conventional diode and thyristor bridge rectifiers create strong harmonic currents which can pollute public utility networks. In an effort to protect utility quality, legislation has been proposed limiting rectifier harmonic output current. As such, companies that manufacture power electronics equipment are constantly looking for new power factor correction (PFC) techniques, and ways to integrate PFC into their products. Figures 1 and 2 are examples of prior art converters which offer PFC. Figure 1 is a three-phase boost rectifier ideal for high power applications which offers unity power factor with continuous input currents. Here, three a.c. phases, Va, Vb, and Vc, are passed through a bridge switching network and over a smoothing capacitor C0 to supply a d.c. load. On the opposite end of the spectrum, Figure 2 shows a prior art three-phase voltage source inverter. Here, a d.c. voltage source Vιn is transformed by a bridge switching network into three-phase a.c. currents, ia, ib, and ic. This type of inverter is widely used in motor drives and Uninterrupted Power Supply (UPS) systems. For both the rectifier in Figure 1 and the inverter in Figure 2, if no soft-switching technique is applied, the six bridge anti-parallel diodes will cause a severe reverse recovery problem due to a high DC rail voltage. For high power applications minority carrier switching devices, such as BJTs, IGBTs, GTOs are often used, which have severe turn-off current tail problem which further exacerbate switching losses and degrade the power factor. As a result, it is extremely difficult to operate such converters at a high switch frequencies (i.e. 20KHz or higher) without implementing soft-switching technique.
A lot of research has been spent on improving the prior art rectifier and inverter circuits, the major thrust being on pulse width modulation (PWM) strategies. Though many useful soft-switching PWM strategies have been developed, none are completely satisfactory. The most advanced available soft-switching techniques are the resonant DC link, the quasi-resonant DC link, and the space- vector based zero-voltage transition. The major drawback of the resonant DC link technique is that the resonant components appear in the main power path and the resonance increases the voltage or current stresses of the switches. The quasi resonant DC link technique requires more complicated control and produces more circulating energy causing high conduction losses. The space-vector based zero-voltage transition technique can only be implemented with high speed digital signal processor and requires many auxiliary components. Additionally, all these techniques are only about zero-voltage switching. Until now, a suitable zero-current switching technique has not been developed. SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide to provide simpler and more effective soft-switching techniques for three- phase converters.
It is yet another object of the present invention to provide simple modifications to the DC rail of a boost rectifier which permits zero- voltage-transition (ZVT) and zero-current-transition (ZCT).
It is yet another object of the present invention to provide simple modifications to the DC rail of a voltage source inverter which permits zero-current-transition (ZCT) and zero-voltage-transition (ZVT).
These and other objects of the present invention are accomplished by adding relatively simple, inexpensive components to the DC rails of conventional converter circuits. For a boost rectifier, an ultra high speed diode, about an order of magnitude faster than the anti-parallel switching diodes, is inserted in the DC rail after the switching network. The reverse recovery current is thereby determined only by this diode and, consequently, much less reverse recovery loss is expected even with a hard switching technique. Zero-current-transition (ZCT) as well as Zero-voltage-transition (ZVT) may also be achieved by adding a simple auxiliary network across the DC rail which operates only during the short turn-on or turn-off transients of the bridge switches. Similarly, a simple, inexpensive auxiliary circuit is added to the DC rail of a conventional voltage source inverter shown in Figure 2 to implement either ZVT and ZCT.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, aspects and advantages will be better understood from the following detailed description of a preferred embodiment of the invention with reference to the drawings, in which:
Figure 1 is a prior art three-phase boost rectifier;
Figure 2 is a prior art three-phase voltage source inverter; Figure 3 is an improved three phase boost rectifier according to the present invention for reducing diode reverse recovery loss;
Figure 4 is a three phase boost rectifier according to the present invention for achieving ZVT;
Figure 5 is a computer generated simulation of the operation of the ZVT rectifier shown in Figure 4;
Figure 6 is a ZCT three-phase boost rectifier according to the present invention;
Figure 7 is a computer generated simulation of the operation of the ZCT rectifier shown in Figure 6; Figure 8 is a ZVT voltage source converter according to the present invention;
Figure 9 is a diagram of control waveforms for the ZVT voltage source converter shown in Figure 8 for ia<0 and ib> ic >0;
Figure 10 is a computer simulation of a the ZVT voltage source inverter shown in Figure 8;
Figure 11 is a is a ZCT voltage source inverter according to the present invention;
Figure 12 is a diagram of control waveforms for the ZCT voltage source inverter shown in Figure 8 for ia<0 and ic > ib>0; Figure 13 is a computer generated simulation of the ZCT operation of the ZCT voltage source inverter shown in Figure 11 ;
Figure 14 is a bi-directional ZVT converter according to the present invention;
Figure 15 is a bi-directional ZCT converter according to the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Referring now to the drawings, and more particularly to Figure 3, there is shown three-phase boost rectifier according to the present invention. The rectifier is similar to the rectifier shown in Figure 1 having a three-phase input, va, vb, and vc, and a bridge switching network comprised of six bridge switches, Sap, San, Sbp, Sbn, Scp, and Scn, hereinafter collectively referred to as simply S. Each bridge switch S has an anti-parallel diode associated therewith. It is understood that these anti-parallel diodes may be either discrete components or the body diode in the case of an active switch such as a MOSFET. According to the invention, an ultra fast diode D is introduced in the d.c. rail prior to a smoothing capacitor C0 supplying a d.c. load. The introduction of the ultra-fast diode D alleviates diode reverse recovery experienced by the diodes in the switching bridge as well as facilitates soft-switching. In the prior art three-phase boost rectifier shown in Figure 1 , at the moment the active switches S (one in each phase) are turned on, any previously conducting anti-parallel diodes will see a high output voltage as:
v ≥v line peak JT.
This high voltage creates a very high reverse recovery current spike in the much slower anti-parallel bridge diodes which in turn causes significant tum-on losses. The ultra fast diode D, which is chosen to be much faster (for example, ten times faster) than the bridge diodes, now determines the reverse recovery current. Consequently, a large reduction in tum-on loss, improved power factor, and a significant increase in the switching frequency is experienced even without implementing a soft-switching technique. However, it is noted that greater advantages can be realized if a soft switching technique is employed in addition. For example, zero-voltage-switching techniques can completely solve the diode reverse recovery problem and remove capacitive turn-on losses. Zero-current-switching techniques can eliminate the turn-off losses of IGBT, GTO, etc. Consequently, if soft¬ switching is also employed the switching frequency can be pushed much higher. This give rise to significant savings of filter inductor size and the circuit cost. Referring now to Figure 4, using the DC rail diode D shown in
Figure 3, it possible to implement zero-voltage-transition ZVT in by adding only one simple auxiliary network on the DC side. The proposed ZVT three-phase boost rectifier is shown in Figure 4, where the auxiliary network consists of resonant inductor Lr, auxiliary switch Saux, and diode Dau.. The auxiliary network only operates during the short tum-on transients of the bridge switches. It is preferred that the bridge switches S are synchronized at their tum-on instants so that the auxiliary ZVT network only operates once per switching cycle. In operation, the auxiliary switch SaιlJl is turned on a short period before the tum-on of the bridge switches S. Therefore, a current builds up in inductor Lr. Once the current in Lr reaches the highest input phase current, resonance begins between Lr and bridge capacitances. This resonance will bring the bridge voltage down to zero thus achieving a ZVS condition for the bridge switches S. Figure 5 shows a computer generated simulation to verify the ZVT operation. The simulation shows one turn-on transient happens at t= 160μs. Since, the switch voltage drops down to zero before its current starts to rise, no tum-on loss occurs.
Referring now to Figure 6, there is shown a ZCT three-phase boost rectifier having an auxiliary network which consists of resonant inductor Lr, resonant capacitor Cr, auxiliary switch Saux, and auxiliary diode Dau.. The auxiliary network is similar to the network shown in Figure 4 with the addition of the resonant capacitor Cr. The ZCT network only operates during the short turn-off transients of the bridge switches S. Again, it is preferred that the bridge switches S are synchronized at their turn-off instants so that the auxiliary ZCT network only operates once per switching cycle. In operation, the auxiliary switch Saux is turned on for a short period before the turn-off of the bridge switches S. A current builds up in Lr as a result of the resonance between Lr and Cr due to the initial voltage on Cr. Once the current in
Cr reaches the highest input phase current, all three phase currents only flow through bridge diodes and no current is left in any bridge switch. Hence, a ZCT turn-off condition is achieved for the bridge switches S. Figure 7 shows a simulation of the ZCT operation for a turn-on transient at t= 160μs. It is noted that there is no overlap between the switch voltage and the switch current indicating no turn-off losses.
All of the boost rectifier circuits of the present invention implement the novel DC rail diode D which has been found to naturally provide a six-step PWM operation which, in prior art circuits not having such a diode, requires a more complicated control circuitry. Briefly, six- step PWM refers to using six optimal bridge voltage vector combinations in a line cycle of 360°, one for each 60°. An optimal bridge voltage vector combination is the zero vector and the two bridge voltage vectors closest to the input voltage vector. Under six-step PWM, the boost inductors are only charged with the input voltage vector (zero-vector), which produces the minimum input current ripple as compared to other PWM schemes which allow the output voltage to participate in charging the boost inductor. Six-step PWM operation is inherent to the present invention because the DC rail diode D prevents the output voltage from participating in the boost inductor charging process. Consequently, undesired vectors are eliminated and the boost inductor current ripple is minimized automatically. In addition to above benefits from this DC rail diode D, another significant advantage is that it eliminates the possibility of shoot-through current from occurring even when both switches S on the same leg or phase of the switching bridge are conducting. Shoot through refers to the output capacitor in a conventional boost rectifier being shorted once both switches on the same leg are conducting. With the DC rail diode of the present invention, this shorting path is eliminated thus providing higher reliability than the conventional circuits.
Similar to the above discussed rectifiers, ZVT and ZCT can be also implemented in a voltage source inverter by adding an active switch on the DC rail side. Referring now to Figure 8, there is shown a soft switching ZVT voltage source inverter according to the present invention. Although a 20KHz inverter switching frequency, not necessarily requiring soft-switching, is fast enough for most motor drive systems to avoid the acoustic noise, soft-switching is still preferred. First, 20KHz is hard to attain for hard-switching high power circuits with currently available devices. Second, for uninterrupted power supply (UPS) systems there is always a demand to reduce the filter inductor size by increasing the switching frequency. Third, for bi¬ directional power flow applications, the off-line rectifier should be able to run as an inverter during regeneration (i.e. operate in reverse as an inverter).
In operation, the inverter shown in Figure 8 the bridge switches are tumed on (i.e by applying gate drive control signals) while the DC rail switch SR is off so that the switches are under zero voltage tum-on condition. Then, the DC rail switch SR is tumed on aided by the ZVT network composed of Lr, Saux, and Daux. An example of the operation is demonstrated in Figure 9 for the case of ia < 0 and ic > ib > 0. In such case with synchronized tum-on scheme, the bridge switches S to be tumed on at the beginning of each switching cycle should be San, Sbp, and Scp. In fact, due to the existence of the DC rail switch, a very simple
PWM scheme can be used which only operates one bridge switch and the DC rail switch SR. This leaves San and Sbp on all the time and only switching Scp and SR to obtain the output current control. In this way, the DC rail voltage is kept at zero during the freewheeling state at the end of every switching cycle and thus provides the zero- voltage turn-on condition for Scp at the beginning of the next switching cycle. In Figure 9, Scp is gated earlier than SR so that it is turned on under zero-voltage condition, which does not change the circuit freewheeling state. At to, the auxiliary switch Sau. is tumed on to build a current in the resonant inductor Lr. The resonant inductor Lr resonates with capacitances across the bridge switches and the DC rail switch SR to provide zero-voltage transition for the turn-on of SR at t, . Times t2 and t3 are determined by the current control loops. Scp is tumed on any time after Sdc is tumed off. At L5, another switching cycle starts. Simulation has been done to verify the ZVT operation. The results are given in Figure 10 which clearly show the zero-voltage tum-on of the bridge switches and the DC rail switch at t= 160μs.
Referring now to Figure 11 , there is shown a zero-current- transition (ZCT) voltage source inverter. The operation principle is that the DC rail switch S is tumed off first with the help of the ZCT network composed of Lr, Cr, Daux, and Saux. The drive signals of the bridge switches are removed after the turn-off of the DC rail switch S so that they are under zero voltage turn-off condition. Hence, no voltage applied on the switches after they are tumed off. One example is shown in Figure 12 which is the same example case used above to explain the ZVT voltage-source-inverter. However, different from the ZVT voltage- source-inverter, the turn-off instants are synchronized. Only one bridge switch Scp and the DC switch S are running under the given condition with Sar and Sbp on all the time. The control waveforms of Figure 12 show Saux gated at to to provide zero-current transition for the turn-off of S at t,. After S is tumed off, the DC link voltage drops down to zero, thus, Scp can be tumed off at t2 without seeing voltage. t3 and t4 are determined by the current control loops. At t5, another switching cycle starts. Simulation has been done to verify the ZCT operation. The results are given in Figure 13. It is noted that there is no overlap between the switch voltage and the switch current for bridge switches or the DC rail switch.
The introduction of the DC rail diode D imposes an undesirable limitation in that the power can flow only in one direction.
However, there are many applications for which this is not an issue such as telecommunication systems and computer systems. Although the circuits embodied in Figures 8 and 11 do not provide soft-switching for the rectifier operation, if the anti-parallel diode of the DC rail switch SR is an ultra fast diode it would serve to alleviate reverse recovery of the anti-parallel bridge diodes. Thus, the above proposed circuit could also be able to deal with bi-directional power flow to certain extent.
If soft-switching is necessary for bi-directional operation, the circuits shown in Figures 14 and 15 may be employed. Figure 14 shows a bi-directional ZVT converter which is a hybrid of the boost rectifier shown in Figures 4 and the voltage source inverter shown in Figure 8. It is noted that if the switch S' and switch Sauxl are kept open the circuit is identical to the boost rectifier of Figure 4. If, on the other hand, Saux2 is open, the circuit becomes functionally equivalent to the voltage source inverter of Figure 8.
Similarly, Figure 15 shows a bi-directional ZCT voltage source inverter which is a hybrid of the boost rectifier shown in Figures 6 and the voltage source inverter shown in Figure 11. If the switch S' and switch Sauxj are kept open the circuit is identical to the boost rectifier of
Figure 4. If Saux2 is open, the circuit becomes functionally equivalent to the voltage source inverter of Figure 8. Hence, depending on the orientation of the switches S, Sauxl, and S^, the circuits of Figures 14 and 15 can operate bi-directionally as either boost rectifiers or voltage source inverters.
While the invention has been described in terms of a single preferred embodiment, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims.

Claims

CLAIMSWe claim:
1. A three-phase boost rectifier for converting a three-phase alternating current power supply to a direct current power supply, comprising: a three-phase alternating current power input; a switching bridge connected between said alternating power input and a direct current rail output, said switching bridge comprising a plurality of switches each having an anti-parallel diode associated therewith; an ultra-fast recovery diode connecting said switching bridge and said direct current rail, said ultra-fast diode being faster than said anti-parallel diodes.
2. A three-phase boost rectifier as recited in claim 1, further comprising a auxiliary circuit connected across said switching bridge for achieving zero-voltage-transition, comprising: a resonant inductor and an auxiliary diode connected in series across said ultra-fast diode; and an auxiliary switch having a first pole connected between said resonant inductor and said auxiliary diode and a second pole connected to ground.
3. A three-phase boost rectifier as recited in claim 1, further comprising a auxiliary circuit connected across said switching bridge for achieving zero-current-transition, comprising: a resonant capacitor, a resonant inductor and an auxiliary diode connected in series across said ultra-fast diode; and an auxiliary switch having a first pole connected between said resonant inductor and said auxiliary diode and a second pole connected to ground.
4. A zero-voltage-transition voltage source inverter for converting a direct current power supply to a three-phase alternating current output, comprising: a direct current power input; a switching bridge connected between said direct current power input and said three-phase alternating current output; and an auxiliary circuit connected between said direct current power input and said switching bridge, said auxiliary circuit comprising: a rail switch connected to a direct current rail of said direct current power input; an auxiliary switch connected in series with a resonant inductor across said rail switch; and an auxiliary diode connected at a first end between said auxiliary switch connected and said resonant inductor and at a second end to ground.
5. A zero-current-transition voltage source inverter for converting a direct current power supply to a three-phase alternating current output, comprising: a direct current power input; a switching bridge connected between said direct current power input and said three-phase alternating current output; and an auxiliary circuit connected between said direct current power input and said switching bridge, said auxiliary circuit comprising: a rail switch connected to the direct current rail of said direct current power input; an auxiliary switch connected in series with a resonant inductor and a resonant capacitor across said rail switch; and an auxiliary diode connected at a first end between said auxiliary switch connected and said resonant inductor and at a second end to ground.
6. A bi-directional zero-voltage-transition (ZVT) converter, comprising: a direct current power terminal; a switching bridge connected between said direct current power terminal and a three-phase alternating current terminal; a rail switch connected to the direct current rail of said direct current power terminal; an ultra fast diode connected in parallel with said rail switch; and an auxiliary circuit connected between said direct current power terminal and said switching bridge, said auxiliary circuit comprising: a first auxiliary switch and anti-parallel diode connected in series with a resonant inductor across said rail switch; and an second auxiliary switch and anti-parallel diode connected at a first end between said first auxiliary switch and said resonant inductor and at a second end to ground, whereby when said rail switch and said first auxiliary switch are open, said converter is a boost rectifier, and if said second auxiliary switch is open, said converter is a voltage source inverter.
7. A bi-directional zero-current-transition (ZCT) converter, comprising: a direct current power terminal; a switching bridge connected between said direct current power terminal and a three-phase alternating current terminal; a rail switch connected to the direct current rail of said direct current power terminal; an ultra fast diode connected in parallel with said rail switch; and an auxiliary circuit connected between said direct current power terminal and said switching bridge, said auxiliary circuit comprising: a first auxiliary switch and anti-parallel diode connected in series with a resonant inductor and a resonant capacitor across said rail switch; and an second auxiliary switch and anti-parallel diode connected at a first end between said first auxiliary switch and said resonant inductor and at a second end to ground, whereby when said rail switch and said first auxiliary switch are open, said converter is a boost rectifier and if said second auxiliary switch is open, said converter is a voltage source inverter.
PCT/US1996/001152 1995-01-23 1996-01-23 Novel soft switched three-phase boost rectifiers and voltage source inverters Ceased WO1996023346A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP52304496A JP3207431B2 (en) 1995-01-23 1996-01-23 New soft-switch three-phase boost rectifier and voltage inverter
EP96905251A EP0806077A4 (en) 1995-01-23 1996-01-23 NEW VOLTAGE-INCREASING THREE-PHASE RECTIFIERS AND VOLTAGE-SUPPLIED INVERTERS WITH SOFT SWITCHING

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US08/376,365 1995-01-23
US08/376,365 US5633793A (en) 1995-01-23 1995-01-23 Soft switched three-phase boost rectifiers and voltage source inverters

Publications (1)

Publication Number Publication Date
WO1996023346A1 true WO1996023346A1 (en) 1996-08-01

Family

ID=23484731

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1996/001152 Ceased WO1996023346A1 (en) 1995-01-23 1996-01-23 Novel soft switched three-phase boost rectifiers and voltage source inverters

Country Status (4)

Country Link
US (1) US5633793A (en)
EP (1) EP0806077A4 (en)
JP (1) JP3207431B2 (en)
WO (1) WO1996023346A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2753018A1 (en) * 1996-08-29 1998-03-06 Abb Patent Gmbh RECTIFIER CIRCUIT INTENDED IN PARTICULAR FOR DIRECT CURRENT MOTORS
EP0833431A3 (en) * 1996-09-27 1999-12-29 ABBPATENT GmbH Three-phase matrix converter and method of operating same
JP3298617B2 (en) 1997-11-07 2002-07-02 サンケン電気株式会社 AC-DC converter
EP2766983A4 (en) * 2011-10-12 2015-08-19 Thermo King Corp MIXED SPEED-OVERVOLT RECTIFIER, REFRIGERATION SYSTEM INCLUDING MIXED SPEED-OVERVOLT RECTIFIER, AND METHOD FOR ELECTRICALLY POWERING A REFRIGERATION UNIT THROUGH A MIXED SPEED-VOLTAGE RECTIFIER

Families Citing this family (38)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9608216D0 (en) * 1996-04-19 1996-06-26 Switched Reluctance Drives Ltd Converter circuit for a polyphase switched inductive load
DE19845995A1 (en) * 1998-04-15 2000-04-13 Andreas Boehringer Power converter with actively influenced commutation
US6239995B1 (en) 1999-03-11 2001-05-29 Ndsu Research Foundation Resonant-boost-input three-phase power factor corrector with a low current stress on switches
DE19942228A1 (en) * 1999-09-03 2001-03-08 Messer Ewm Gmbh Circuit arrangement for an active rectifier
DE10102408A1 (en) * 2001-01-15 2002-07-18 Dietrich Eckert Procedure for three-phase connection for electronic ballasts
US6385057B1 (en) * 2001-01-31 2002-05-07 Bartronics, Inc. Power conversion system and method of power conversion
SE521885C2 (en) * 2001-04-11 2003-12-16 Abb Ab DC Drives
US7142439B2 (en) * 2002-10-23 2006-11-28 Fairchild Semiconductor Corporation Zero-voltage-switching single-switched resonant DC link with minimized conduction loss
US7148660B2 (en) * 2004-09-30 2006-12-12 General Electric Company System and method for power conversion using semiconductor switches having reverse voltage withstand capability
JP5060962B2 (en) * 2005-01-28 2012-10-31 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ Method and inverter for converting DC voltage to three-phase AC output
US8052590B2 (en) * 2005-07-07 2011-11-08 Xerox Corporation Amorphous metal components for a reproduction machine
JP4725979B2 (en) * 2005-07-15 2011-07-13 国立大学法人東北大学 Sensor tag, sensor tag device, power receiving circuit, and power supply method for sensor tag device
US7518895B2 (en) * 2006-06-30 2009-04-14 Fairchild Semiconductor Corporation High-efficiency power converter system
JP2011182613A (en) * 2010-03-04 2011-09-15 Denso Corp Power conversion system
CN102986128B (en) * 2010-08-25 2016-05-04 富士电机株式会社 Power converter
US20120126758A1 (en) * 2010-11-19 2012-05-24 Hamilton Sundstrand Corporation High voltage dc power generation
EP2777146A1 (en) * 2011-11-11 2014-09-17 ABB Technology AG A converter cell and associated converter arm and method
US8901897B2 (en) 2012-03-02 2014-12-02 International Business Machines Corporation Operating a DC-DC converter
US9281748B2 (en) 2012-03-02 2016-03-08 Lenovo Enterprise Solutions (Singapore) Pte. Ltd. Operating a DC-DC converter
EP2642653A1 (en) * 2012-03-20 2013-09-25 C. & E. Fein GmbH Driver switch and control method
KR20150118081A (en) * 2012-09-05 2015-10-21 에이비비 테크놀로지 아게 Interleaved 12-pulse rectifier
US9270201B1 (en) 2012-10-25 2016-02-23 mPower Solar Inc. Solar inverter
US10027114B2 (en) * 2012-10-25 2018-07-17 Mpowersolar Inc. Master slave architecture for distributed DC to AC power conversion
JP5841098B2 (en) * 2013-05-08 2016-01-13 ビステオン グローバル テクノロジーズ インコーポレイテッド Zero current switching circuit and full bridge circuit
US9236347B2 (en) 2013-10-09 2016-01-12 Lenovo Enterprise Solutions (Singapore) Pte. Ltd. Operating and manufacturing a DC-DC converter
EP2911287A1 (en) * 2014-02-24 2015-08-26 Danfoss Power Electronics A/S Apparatus and method for reducing harmonics
WO2015155823A1 (en) * 2014-04-07 2015-10-15 三菱電機株式会社 Power conversion device and power conversion control method
JP6444090B2 (en) * 2014-08-01 2018-12-26 キヤノン株式会社 Rectification smoothing circuit, power supply device and image forming apparatus
US9219422B1 (en) 2014-08-21 2015-12-22 Lenovo Enterprise Solutions (Singapore) Pte. Ltd. Operating a DC-DC converter including a coupled inductor formed of a magnetic core and a conductive sheet
US9379619B2 (en) 2014-10-21 2016-06-28 Lenovo Enterprise Solutions (Singapore) Pte. Ltd. Dividing a single phase pulse-width modulation signal into a plurality of phases
US9618539B2 (en) 2015-05-28 2017-04-11 Lenovo Enterprise Solutions (Singapore) Pte. Ltd. Sensing current of a DC-DC converter
JP6103031B1 (en) * 2015-12-28 2017-03-29 ダイキン工業株式会社 Control device for power converter
JP2019533419A (en) * 2016-10-19 2019-11-14 イマログ インコーポレイテッド Hybrid rectifier
JP6702209B2 (en) 2017-01-26 2020-05-27 株式会社デンソー Power converter
CN110277912B (en) * 2018-03-15 2021-01-22 株洲中车时代电气股份有限公司 Direct current boost conversion circuit
CN110350783B (en) * 2018-04-08 2024-08-13 佛山科学技术学院 A boost module for UPS
CN111614253A (en) * 2020-04-27 2020-09-01 驰驱电气(嘉兴)有限公司 A quasi-resonant motor drive topology circuit
DE102022205497A1 (en) * 2022-05-31 2023-11-30 Rolls-Royce Deutschland Ltd & Co Kg Voltage adjustment in a power system that has a high power density inverter

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4864483A (en) * 1986-09-25 1989-09-05 Wisconsin Alumni Research Foundation Static power conversion method and apparatus having essentially zero switching losses and clamped voltage levels
US5255175A (en) * 1989-05-15 1993-10-19 Kabushiki Kaisha Toshiba Power generation system having induction generator and controlled bridge rectifier
US5291388A (en) * 1992-04-16 1994-03-01 Westinghouse Electric Corp. Reconfigurable inverter apparatus for battery-powered vehicle drive
US5367448A (en) * 1992-08-07 1994-11-22 Carroll Lawrence B Three phase AC to DC power converter
US5432695A (en) * 1993-09-17 1995-07-11 The Center For Innovative Technology Zero-voltage-switched, three-phase PWM rectifier inverter circuit

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE9016809U1 (en) * 1990-12-12 1991-02-28 Siemens AG, 8000 München Voltage source converter circuit
JPH04322167A (en) * 1991-04-19 1992-11-12 Takaoka Electric Mfg Co Ltd Single phase rectified power supply apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4864483A (en) * 1986-09-25 1989-09-05 Wisconsin Alumni Research Foundation Static power conversion method and apparatus having essentially zero switching losses and clamped voltage levels
US5255175A (en) * 1989-05-15 1993-10-19 Kabushiki Kaisha Toshiba Power generation system having induction generator and controlled bridge rectifier
US5291388A (en) * 1992-04-16 1994-03-01 Westinghouse Electric Corp. Reconfigurable inverter apparatus for battery-powered vehicle drive
US5367448A (en) * 1992-08-07 1994-11-22 Carroll Lawrence B Three phase AC to DC power converter
US5432695A (en) * 1993-09-17 1995-07-11 The Center For Innovative Technology Zero-voltage-switched, three-phase PWM rectifier inverter circuit

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP0806077A4 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2753018A1 (en) * 1996-08-29 1998-03-06 Abb Patent Gmbh RECTIFIER CIRCUIT INTENDED IN PARTICULAR FOR DIRECT CURRENT MOTORS
EP0833431A3 (en) * 1996-09-27 1999-12-29 ABBPATENT GmbH Three-phase matrix converter and method of operating same
JP3298617B2 (en) 1997-11-07 2002-07-02 サンケン電気株式会社 AC-DC converter
EP2766983A4 (en) * 2011-10-12 2015-08-19 Thermo King Corp MIXED SPEED-OVERVOLT RECTIFIER, REFRIGERATION SYSTEM INCLUDING MIXED SPEED-OVERVOLT RECTIFIER, AND METHOD FOR ELECTRICALLY POWERING A REFRIGERATION UNIT THROUGH A MIXED SPEED-VOLTAGE RECTIFIER

Also Published As

Publication number Publication date
US5633793A (en) 1997-05-27
EP0806077A4 (en) 2000-08-30
JP3207431B2 (en) 2001-09-10
JPH11506599A (en) 1999-06-08
EP0806077A1 (en) 1997-11-12

Similar Documents

Publication Publication Date Title
US5633793A (en) Soft switched three-phase boost rectifiers and voltage source inverters
US5047913A (en) Method for controlling a power converter using an auxiliary resonant commutation circuit
Mao et al. Review of high-performance three-phase power-factor correction circuits
US5486752A (en) Zero-current transition PWM converters
US5889667A (en) Quasi-resonant buck converter with soft switching
Matsui et al. High-frequency link DC/AC converter with suppressed voltage clamp circuits-naturally commutated phase angle control with self turn-off devices
Hua et al. Novel zero-current-transition PWM converters
Cuadros et al. Space vector modulated, zero-voltage transition three-phase to DC bidirectional converter
Hua et al. Soft-switching techniques in PWM converters
US6330170B1 (en) Soft-switched quasi-single-stage (QSS) bi-directional inverter/charger
US7768800B2 (en) Multiphase converter apparatus and method
Jiang et al. Simple high performance three-phase boost rectifiers
Wang et al. Novel dc-rail soft-switched three-phase voltage-source inverters
US20120218785A1 (en) Three-Level Active Neutral Point Clamped Zero Voltage Switching Converter
JPH10505218A (en) Improved zero voltage transition (ZVT) three-phase PWM voltage link converter
Kim et al. New bilateral zero voltage switching AC/AC converter using high frequency partial-resonant link
Divan Low stress switching for efficiency
Wu et al. A review of soft-switched DC-AC converters
Teichmann et al. ARCP soft-switching technique in matrix converters
Wakabayashi et al. A new family of zero-current-switching PWM converters and a novel HPF-ZCS-PWM boost rectifier
Li et al. Performance evaluation of isolated dc/dc converters in modularized bridge rectifier solid-state transformer
Bose Need a switch?
Chen et al. Soft-switched inverter for electric vehicle drives
Wang et al. A new quasi-single-stage isolated three-phase ZVZCS buck PWM rectifier
Matsui Bidirectional soft switching arm topology for a nonresonant HF link converter

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CA JP

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
ENP Entry into the national phase

Ref country code: JP

Ref document number: 1996 523044

Kind code of ref document: A

Format of ref document f/p: F

WWE Wipo information: entry into national phase

Ref document number: 1996905251

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 1996905251

Country of ref document: EP

WWW Wipo information: withdrawn in national office

Ref document number: 1996905251

Country of ref document: EP