JPH089651A - Control method for high frequency isolated inverter system - Google Patents

Abstract

(57) [Abstract] [Purpose] Reduction of output voltage waveform distortion of a high-frequency isolated inverter system including a high-frequency inverter and a high-frequency rectifier circuit equipped with an RCD snubber, and effective regeneration of power to a DC power supply. Try to suppress the output current. A discharge operation of a snubber provided in the high-frequency rectifier circuit, which forms a bridge circuit by a semiconductor switching element having a diode connected in anti-parallel, in relation to the duration of a pulse-shaped input voltage signal of the rectifier circuit. A discharge ignition signal S _4D defined by a residual obtained by subtracting a margin time which is a sum of the reverse recovery time and an arc extinction margin time;
One of the minimum ensuring signal S _MIN and the longer one of them is always selected by the OR element OR to ensure the required signal S _4DO and the discharge time of the snubber. Further, as shown in FIG. 3, the secondary side excitation of the high frequency transformer is performed by the residual energy of the circuit element on the AC output side, and the current is suppressed through the power regeneration of the residual energy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for a high frequency insulated inverter system as a power converter which is composed of a high frequency inverter, a high frequency transformer, a high frequency rectifier circuit, etc. More specifically, the present invention relates to a snubber discharge period control method provided in the high-frequency rectifier circuit.

[0002]

2. Description of the Related Art As a conventional high-frequency isolated inverter system to be controlled by the present invention, one illustrated in the main circuit diagram of FIG. 4 is known. Note that FIG. 5 is an operation waveform diagram of the drive signal for each main circuit switching element shown in FIG. As shown in FIG. 4, the high-frequency isolated inverter system described above includes a high-frequency inverter 2 fed from a DC power source 1 having a capacitor C _D connected in parallel and having a voltage V _DC, and its primary winding. Is excited by the inverter 2 and has a single-phase high-frequency transformer (HFT) 3 having a center tap in its secondary winding, and the high-frequency rectification proposed in 1992 Patent Application No. 253353 regarding its basic configuration and operating principle. The circuit 4, the capacitor C _S , the diode D _S , the resistor R _S , and the RCD-type snubber 41 consisting of the series-parallel connection as shown in the figure, and the reactors L _F1 , L _F2 ,
The capacitor C _F comprises a filter circuit composed of three connections as shown in the figure, and converts a DC input fed from a terminal P-N into an AC, outputs it from a terminal R-S, and feeds a load 5. .

The operation of the inverter system will be described below with reference to FIG. First, a DC input from the DC power supply 1 is modulated into a single-phase positive / negative voltage by a high frequency inverter 2 composed of semiconductor switching elements each having a flywheel diode, and a high frequency transformer (HFT) 3 via a terminal U-V. Is applied to the primary winding to excite the transformer 3.

The center tap of the secondary winding of the transformer 3 is connected to the AC output terminal S via the terminal O,
Both ends u and v of the secondary winding are connected to a terminal X and a terminal Y of the high frequency rectifier circuit 4, respectively, and a terminal Z of the rectifier circuit is connected to an AC output terminal R via the filter circuit. . The RCD type snubber 41, which is composed of a capacitor C _S , a diode D _S and a resistor R _S and is connected as shown in the figure, is a cathode side bus bar of each upper arm diode of the first to third arm pairs in the rectifying circuit 4. And the anode side bus of each lower arm diode.

In the above circuit configuration, the high frequency rectifier circuit 4
S _{1 to} S ₆ are transistors as semiconductor switching elements, and are on / off controlled according to the polarity of the excitation voltage for the high frequency transformer 3 and the polarity of the AC output voltage from the terminal RS. Each of the switching elements S ₁ to
The energization pattern inside the high-frequency rectifier circuit 4 that flows through S ₆ and each of the diodes D _{1 to} D ₆ is as follows.

The polarity of the exciting voltage applied to the high frequency transformer 3 is such that the terminal u is opposite to the terminal v of the secondary winding of this transformer.
A positive voltage is generated when a + voltage is generated on the terminal S, and a positive voltage output is generated when a + voltage is generated on the terminal R with respect to the terminal S, and a current flowing from the terminal R to the terminal S is a positive current. . (1) The S ₅ when outputting a positive voltage between the terminals R-S is turned on, the excitation voltage of the transformer 3 is an S ₁ in the case of positive polarity, the S ₃ in the case of negative polarity, also When the excitation voltage is zero, both S ₁ and S ₃ are turned on.

When the output from the terminal RS is a positive current output due to each of the above-mentioned ON operations, D ₁ → S ₅ , D
₃ → S ₅ , or D ₁ , D ₃ → S ₅ , and when the output from the terminal RS is a negative current output, D ₅ → S ₁ , D ₅ → S ₃ , Alternatively, flow as D ₅ → S _1, S ₃ . (2) the S ₆ when outputting a negative voltage between the terminals R-S is turned on, the excitation voltage of the transformer 3 is a S ₂ in the case of positive polarity, the S ₄ in the case of negative polarity, also When the excitation voltage is zero, both S ₂ and S ₄ are turned on.

When the output from the terminal RS is a positive current output due to each of the above-mentioned ON operations, S ₂ → D ₆ , S
₄ → D ₆ , or S ₂ , S ₄ → D ₆ , and when the output from the terminal RS is a negative current output, S ₆ → D ₂ , S ₆ → D ₄ , Alternatively, flow as S ₆ → D _2, D ₄ . Further, regarding the snubber 41 that absorbs the follow-up energy based on the leakage reactance of the high frequency transformer 3, the discharge of the snubber is controlled so as to be performed during the excitation period of the transformer 3 in order to avoid excessive discharge. Yes, during the positive excitation period of the transformer 3, S _1, S
₄ turns on the both the negative exciting period and on both S _2, S _3, respectively discharge path is formed.

FIG. 5 shows operation waveforms of the driving signals for the switching elements S _{1 to} S ₆ corresponding to the above-described operation. In FIG. 5, V _O is an AC voltage output from the terminal R-S, V _EX is an exciting voltage of the transformer 3, and a pulse corresponding to the voltage V _O is formed by PWM control in the high frequency inverter 2. Voltage.
Further, S _{1D to} S _6D are drive signals for the switching elements S _{1 to} S ₆ , respectively.

As shown in both FIGS.
The switching elements S _5, S ₆ in the third arm pair define the polarity of the AC voltage V _O , and the upper switching elements S _1, S ₃ and the lower switching element S _{2 in the first and} second arm pairs. _, S ₄ function in pairs with each other,
The exciting voltage V _EX is rectified according to the polarities defined by the two elements S _{5 and} S ₆ .

[0011]

The conventional control method for the high frequency isolated inverter system as described above has the following problems. That is, (1) As described above, it is necessary to discharge the snubber 41 during the excitation period of the high frequency transformer 3, and in consideration of the reverse recovery time and the arc extinction time of the diode in each charging path of the snubber, S ₄ in both the combination of the switching elements S ₁ and S _4, S ₂ and S ₃ of forming a discharge path of the snubber
Alternatively, the ON operation of S ₃ needs to be performed inside the exciting voltage applied to the transformer 3, that is, within each pulse width of the exciting voltage forming the pulse train.

However, when the inverter system outputs a low voltage, that is, when the pulse width of the exciting voltage pulse train applied to the transformer 3 is narrow, the element S ₄
Alternatively, the required ON period of S ₃ cannot be secured, and the snubber cannot be discharged. According to the conventional control method, at the time of low voltage output of the inverter system in which it becomes difficult to secure the snubber discharge period as described above, in order to avoid the inflow of non-dischargeable energy to the snubber, the high frequency transformer 3 by the high frequency inverter 2 is prevented. I had no choice but to stop the excitation. Therefore, in the above-mentioned inverter system, it becomes difficult to control the low-voltage output, resulting in waveform distortion in the output voltage.

(2) In a normal bridge type inverter, when a current exceeding a specified value is applied, the required current is suppressed by turning off all the switching elements forming the bridge. In the illustrated inverter system, if all the switching elements in the high-frequency rectifier circuit 4 are turned off to suppress the current as described above, the stored energy of the filter circuit reactor or the like in the output path of this rectifier circuit flows into the snubber. It will be.

Therefore, according to the conventional control method for the inverter system, it is necessary to determine the rated capacity of the capacitor, diode, etc. constituting the snubber as being suitable for the snubber inflow current due to the stored energy. Therefore, each element of the snubber is inevitably large and expensive. Incidentally, FIG. 6 is an operation waveform diagram of the drive signal of the switching element for snubber discharge, and the case where the transformer 3 is excited by the positive polarity and outputs the positive voltage from the terminal RS is a target example. The above problem is explained, and the device S ₄ is targeted as the discharging switching device.

In FIG. 6, S _EX is 1 of the transformer 3.
It is a primary excitation signal that commands the voltage applied to the secondary winding, and is formed by PWM control of the inverter 2. The primary applied voltage of the transformer 3 by this signal is transformed at a predetermined winding ratio and the secondary voltage V is applied. Become _EX . Further, E _D is the peak value of the voltage V _EX , and t ₁ and t ₂ are the reverse recovery time and the arc-extinguishing margin time for the diode, respectively.

6 (a) and 6 (b) are operation waveform diagrams respectively corresponding to the normal voltage output state and the low voltage output state in the inverter system. Figure 6
In (a), the element S ₄ that defines the snubber discharge period
Even when the sum of both the times t ₁ and t ₂ is taken into consideration, the ON operation period is within the continuation width of the excitation voltage V _EX , and the snubber discharge can be reliably performed.

Contrary to this, in FIG. 6B, the continuation width of the excitation voltage V _EX becomes narrow, and the times t ₁ and t ₂
Considering the sum of the two, the on-operation period of the element S ₄ disappears and the snubber discharge becomes impossible. In addition, FIG.
It is a figure which shows the electricity supply path | route at the time of current suppression control of the inverter system shown in FIG. 4, and the dotted line path | route shown in figure corresponds to the conventional control method. That is, according to the conventional method,
Since all the elements S _{1 to} S ₆ are turned off during the current suppression control, current can be supplied only through the diode.
There is no choice but to energize the snubber capacitor C _S and the diode D _{S as} shown by the dotted line path in the figure. Further, it is difficult to consume energy in this energized state, and therefore the current reduction time becomes long. In the illustrated case, the output current polarity immediately before the start of the current suppression control is positive.

In view of the above, the present invention is directed to a high-frequency isolated inverter system including a high-frequency inverter, a high-frequency transformer, a high-frequency rectifier circuit having an RCD type snubber, and the like. It is an object of the present invention to provide a control method of the inverter system, which enables reduction of the voltage waveform distortion of the device, avoidance of increase in the required capacity of the snubber due to the output current suppression control, and reduction of the current reduction time. .

[0019]

In order to achieve the above object, in a control method for a high frequency isolated inverter system according to the present invention, 1) a high frequency inverter according to claim 1 and a primary winding excited by this inverter are provided. Single-phase high-frequency transformer having a wire and a secondary winding with a center tap, and six semiconductor switching elements each having a diode connected in anti-parallel, each of which constitutes a first to third arm pair bridge A circuit, wherein the two AC terminals of the first and second arm pairs are respectively connected to both ends of the secondary winding of the high frequency transformer, and the AC terminals of the third arm pair and the high frequency transformer 2 are connected. A high-frequency rectifier circuit configured to output an AC voltage between the center taps of the secondary windings, and a filter circuit provided on the output side of the rectifier circuit. And a high-frequency insulation type in which a snubber composed of a resistor, a capacitor, and a diode is connected between the positive-side bus of the upper arm and the negative-side bus of the lower arm in the three arm pairs of the rectifier circuit. Regarding the inverter system, during the low voltage control period near the zero voltage output, the discharge period of the snubber is fixed to a predetermined value by on / off control of the switching elements in the first and second arm pairs. .

2) According to a second aspect of the present invention, in the method of controlling the high frequency isolated inverter system according to the first aspect, the snubber discharge period is matched with the excitation period of the high frequency transformer instead of the fixed control of the snubber discharge period. I shall. 3) According to claim 3, a high-frequency inverter, a single-phase high-frequency transformer having a primary winding excited by this inverter and a secondary winding with a center tap, and six pieces each having a diode connected in anti-parallel A bridge circuit comprising first to third arm pairs composed of semiconductor switching elements, wherein two AC terminals of the first and second arm pairs are connected to both ends of a secondary winding of the high frequency transformer. And a high-frequency rectifier circuit configured to output an AC voltage between the AC terminals of the third arm pair and the center tap of the secondary winding of the high-frequency transformer, and provided on the output side of the rectifier circuit. And a resistor circuit between the positive side bus bar of the upper arm and the negative side bus bar of the lower arm in the three arm pairs of the rectifier circuit. In a high frequency isolated inverter system configured by connecting a snubber composed of a capacitor and a diode, in the output current suppression control when the load is short-circuited, excitation of the high frequency transformer by the high frequency inverter is stopped, and Through the on / off control of the six switching elements in the third to third arm pairs, the snubber excites the excitation from the secondary side of the high frequency transformer due to the residual energy in the output side circuit elements of the high frequency rectifier circuit. It should be done without going through.

[0021]

As described above, the high-frequency insulated inverter system including the high-frequency inverter, the high-frequency transformer, and the high-frequency rectifier circuit including the RCD snubber is as described above.
If the snubber can be surely discharged regardless of the output voltage state including low voltage output of the system without stopping the excitation of the high frequency transformer, waveform distortion in the output voltage of the system Can be reduced.

Further, during output current suppression control due to load short circuit of the system, the residual energy in the inductive element or the like in the output path of the system does not go through the snubber but goes through the high frequency transformer to a high frequency. If you control to regenerate to the power supply side of the inverter,
The output current can be efficiently and rapidly suppressed without increasing the capacity of the snubber.

According to the above, the present invention is as follows: 1) According to claim 1, in the high frequency isolated inverter system, in the low voltage control period near the zero voltage output, the first and second high frequency rectification circuits. The on / off control of the switching elements of both arm pairs fixes the discharge period of the snubber to a predetermined value so that its minimum value can be secured.

2) According to a second aspect, in the control method of the high frequency isolated inverter system according to the first aspect,
Instead of the fixed control of the snubber discharge period, the discharge period of the snubber is made to coincide with the excitation period of the high frequency transformer. Incidentally, the snubber is unlikely to be over-discharged in the low voltage output state of the inverter system.Therefore, in the low voltage output state, it is essential to set the margin time for the diode for the purpose of avoiding the over-discharge. Don't

3) According to a third aspect of the present invention, in the high frequency isolated inverter system, in the output current suppressing control when the load is short-circuited, the excitation of the high frequency transformer by the high frequency inverter is stopped and the first high frequency transformer is stopped.
Through on / off control of the six switching elements in the third three arm pairs, the secondary side excitation of the high frequency transformer due to the residual energy in the output path element of the high frequency rectifier circuit does not pass through the snubber. The residual energy is regenerated to the DC power source side of the high frequency inverter.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the logic circuit diagrams of FIGS. First, FIG. 1 shows a first embodiment of the present invention corresponding to claim 1, and it is intended to secure a discharge time of the snubber even in a low voltage output state of the high frequency isolated inverter system. .

As in the case of FIG. 6, FIG. 1 shows a case where the ON time of the switching element S ₄ becomes the discharge time of the snubber as an example of the target, and the same applies to the switching element S _3. is there. In FIG.
R is an OR element. Further, S _4D is an ON operation command signal for the element S ₄ which is formed in consideration of the above margin time regarding the diode as shown in FIG.
The discharge ignition signal defines the discharge period of the snubber.
Further, S _MIN is a minimum securing period signal that defines the minimum value of the discharge period of the snubber, and S _4DO is a corrected final ON operation command signal for the element S ₄ as a discharge switch.

That is, the signal S _4DO is the signal S _4D and the signal S _MIN.
Is the OR output of the signal S _4D
Alternatively, it is formed as a signal of the longer one of S _MIN , whichever is longer.
The duration of the signal S _4D decreases from a state longer than that of the signal S _MIN to zero as the voltage output state of the inverter system changes from its rated state to a low voltage state. Therefore, the signal S _4DO becomes its shortest value with the duration of the signal S _MIN .

That is, the discharge of the snubber due to the ON operation of the element S ₄ secures the period designated by the signal S _MIN as a fixed minimum value. Next, FIG. 2 shows a second embodiment of the present invention corresponding to claim 2, and even in the low voltage output state of the high frequency isolated inverter system, the snubber is the same as in the case of claim 1. It is intended to secure the discharge time of.

As in the case of FIG. 1, FIG. 2 shows an example of the case where the on time of the switching element S ₄ becomes the discharge time of the snubber, and the same applies to the switching element S _3. is there. Further, the same display symbols are attached to the components or signals having the same functions as those in the case of FIG. As shown in FIG. 2, the device ON operation command signal is modified for S ₄ S _4DO, said such discharge ignition signal S _4D of the case is longer than the minimum reserved period signal S _MIN said signal with a the signal S _4D Like S _4DO ,
When the signal S _4D is shorter than the signal S _MIN , the excitation signal S _EX is determined to be the signal S _4DO .

That is, the signal S _4DO is the signal S _EX.
And a signal S _MIN and an overlapped part signal by an AND element AND the signal S _4D and a signal S by a logical inversion element INV.
The signal is formed as the longer one of the inverted signal of _MIN and the overlapping portion signal by the AND element AND.
FIG. 3 shows a third embodiment of the present invention corresponding to claim 3, and each circuit element of the output path of the high frequency rectifier circuit 4 shown in FIG. 4 during the output current suppression control of the inverter system. The residual energy in is regenerated to the power source side capacitor C _D of the high frequency inverter 2 without passing through the snubber 41.

In FIG. 3, constituent elements or signals having the same functions as those in FIG. 1 or 2 are designated by the same reference numerals. FIG. 3 shows each of the switching elements S _{1 to} S ₆ of the high frequency rectifier circuit 4 during the output current suppression control.
FIG. 3 is a logic circuit diagram for performing a drive command for each of the signals S _{1D to} S _6D shown in the figure are ON / OFF command signals for the respective elements S _{1 to} S ₆ during normal operation, and each signal S
_1DO ~S _6DO is ON / OFF command signal corrected for each element obtained respectively without the condition added to each signal S _1D to S _6D.

Further, the signal S _LC is above the normal operation and the output level H, the output level is intended to be commanded state of the control of the output current suppression with a state of change to L, S _D50 is The duty command signal S _D when the command duty ratio is 50% is shown. Further, as shown in the drawing, each two logic elements INV and A are cross-connected.
The duty command circuit composed of ND and ND is activated by the signal S _LC , and outputs two sets of duty command signals which are conjugate with each other according to the signal S _D50 from the respective AND elements.

Now, if the inverter system is in a normal operation state, the output level of the signal S _LC is H,
Therefore, the duty command circuit does not operate, while the AND states of the signals S _{1D to} S _6D and S _LC are established, the signals S _{1D to} S _4D pass through the respective logic elements OR, and the signal S _5D. ，
S _6D is directly output, respectively. Therefore, the signal S
_1DO ~S _6DO becomes each thing the same as the signal S _1D to S _6D.

Further, when the inverter system is in the output current suppression control state, the output level of the signal S _LC is L, and therefore the A of each of the signals S _{1D to} S _6D and S _LC.
The ND state is resolved, and the signals S _5DO and S _{6DO enter} the OFF command state. On the other hand, the above-mentioned duty command circuit outputs two sets of duty command signals which are in an activated state and are mutually conjugate, and the signal S _1DO is interlocked with each of these command signals.
And S _4DO , and S _2DO and S _{3DO form a} pair and _enter the same command state.

That is, in the output current suppression control state, regarding the switching elements S _{1 to} S ₆ shown in FIG.
Both elements S ₅ and S ₆ are continuously turned off, and
The elements S ₁ and S ₄ , S ₂ and S ₃ respectively perform the same operation, and perform on / off operations which are conjugate with each other according to the duty command signal. During the output current suppression control, the excitation of the high frequency transformer 3 by the high frequency inverter 2 in FIG. 4 is stopped.

The energization path in the output current suppression control state as described above is shown by a thick solid line in FIG. The state shown in the drawing shows the case where the elements S ₁ and S ₄ are in the on state and the elements S ₂ and S ₃ are in the off state. in this case,
Since the main circuit current passes through the element S ₄ , it does not pass through the snubber 41. Further, the main circuit current passes between the terminals o and v of the high frequency transformer 3 and excites this transformer from its secondary side.

Further, when the operating states of the respective elements are reversed, the elements S ₂ and S ₃ are turned on, and the elements S ₁ and S ₄ are turned off, the main circuit current is the transformer 3 Between the terminals o and u and the element S ₂ , but does not pass through the snubber 41. That is, the transformer 3 has a secondary side excitation of o.
2 by alternately inverting → v, o → u
Power can be transferred from the secondary side to the primary side.

Therefore, the energy for energizing the main circuit current, that is, the residual energy in each element of the output path of the high frequency rectifier circuit 4 in FIG. 4, does not pass through the snubber 41, but passes through the high frequency transformer 3 and the high frequency inverter 2 Will be regenerated to the power source side capacitor C _D.

[0040]

According to the present invention, a high-frequency inverter, a single-phase high-frequency transformer having a secondary winding with a center tap, the primary winding of which is excited by the inverter, and a diode connected in antiparallel to each other. 6 semiconductor switching elements having a pair of three first to third arm pairs to form a bridge structure, and the two AC terminals of the first and second arm pairs are connected to the secondary of the high frequency transformer. A high-frequency rectifier circuit, which is connected to both ends of a winding and is configured to output an AC voltage between an AC terminal of the third arm pair and a center tap of a secondary winding of the high-frequency transformer, and a rectifier circuit of this rectifier circuit. A filter circuit provided on the output side, and a resistor and a capacitor are provided between the positive electrode side bus bar of the upper arm and the negative side bus bar of the lower arm in the three arm pairs of the rectifier circuit. A high-frequency isolated inverter system in which a snubber composed of a capacitor and a diode is connected, and a switching element in the pair of first and second arms is turned on during a low voltage control period near the zero voltage output. By off control, the discharge period of the snubber is fixed to a predetermined minimum securing period as in claim 1, or the discharge period of the snubber matches the excitation period of the high frequency transformer as in claim 2. By doing so, it becomes possible to secure the required discharge period of the snubber regardless of the output voltage state including the low voltage output, and therefore, to avoid the overcharging of the snubber due to incapable or insufficient discharge. It is not necessary to stop the excitation of the high-frequency transformer by the high-frequency inverter. It becomes possible to eliminate or reduce the waveform distortion in the input voltage, and further, in the inverter system, when the output current is suppressed due to the load short circuit or the like, the high frequency transformer by the high frequency inverter according to claim 3. Is stopped and the on / off control of the six switching elements in the first to third three arm pairs in the high-frequency rectifier circuit is performed to eliminate residual energy in inductive elements and the like in the output path of the inverter system. It becomes possible to regenerate the power-side capacitor of the high-frequency inverter via the high-frequency transformer without passing through the snubber, and to efficiently and rapidly output the output current without increasing the capacity of the snubber. Can be suppressed.

[Brief description of drawings]

FIG. 1 is a logic circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a logic circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a logic circuit diagram showing a third embodiment of the present invention.

[Fig. 4] Main circuit diagram of high-frequency isolated inverter system

5 is an operation waveform diagram of a main circuit switching element driving signal corresponding to FIG.

FIG. 6 is an operation waveform diagram of a signal for driving a switching element for snubber discharge.

FIG. 7 is a conduction path diagram during output current suppression control in the main circuit corresponding to FIG.

[Explanation of symbols]

1 DC power source 2 frequency inverter 3 frequency transformer (HFT) 4 RF clear stream circuit 5 loads 41 snubber C capacitor (C _D, C _{F) D} diode (D ₁ ~D ₆₎ L _F filter reactor (L _F1, L _F2) S Switching transistors (S _{1 to} S ₆ ) AND logical product element OR logical sum element INV logical inversion element

Claims (3)

[Claims] 1. A single-phase high-frequency transformer having a high-frequency inverter, a primary winding excited by this inverter, and a secondary winding with a center tap, and six semiconductor switching devices each having a diode connected in antiparallel. It is a bridge circuit composed of first to third arm pairs composed of elements, wherein two AC terminals of the first and second arm pairs are respectively provided at both ends of a secondary winding of the high frequency transformer. A high-frequency rectifier circuit that is connected to the third-arm pair and outputs an AC voltage between the center tap of the secondary winding of the high-frequency transformer, and a filter provided on the output side of the rectifier circuit. And a resistor, a capacitor, and a datum between the positive side bus of the upper arm and the negative side bus of the lower arm in the three arm pairs of the rectifier circuit. Formed by connecting the configuration was snubber from Eau tripartite relates frequency isolated inverter system,
In the low voltage control period near the zero voltage output, the discharge period of the snubber is fixed to a predetermined value by the on / off control of the switching elements in the first and second arm pairs. Control method for inverter inverter system. 2. The control method for a high frequency isolated inverter system according to claim 1, wherein the snubber discharge period is matched with the excitation period of the high frequency transformer, instead of fixed control of the snubber discharge period. Control method for high frequency isolated inverter system. 3. A high-frequency inverter, a single-phase high-frequency transformer having a primary winding excited by this inverter and a secondary winding with a center tap, and six semiconductor switching devices each having an antiparallel connected diode. It is a bridge circuit which is composed of elements and constitutes a first to a third arm pair, wherein two AC terminals of the first and second arm pairs are respectively provided at both ends of a secondary winding of the high frequency transformer. A high-frequency rectifier circuit that is connected and configured to output an AC voltage between the AC terminals of the third arm pair and the center tap of the secondary winding of the high-frequency transformer, and a filter provided on the output side of the rectifier circuit. And a resistor, a capacitor, and a datum between the positive side bus of the upper arm and the negative side bus of the lower arm in the three arm pairs of the rectifier circuit. Formed by connecting the configuration was snubber from Eau tripartite relates frequency isolated inverter system,
In the output current suppression control when the load is short-circuited, the excitation of the high frequency transformer by the high frequency inverter is stopped, and the on / off control of the six switching elements in the first to third arm pairs is performed.
A method for controlling a high frequency insulated inverter system, wherein excitation from the secondary side of the high frequency transformer by residual energy in each output side circuit element of the high frequency rectification circuit is performed without passing through the snubber.