JPH07337026A - PWM controller - Google Patents

Abstract

(57) [Abstract] [Purpose] To generate a carrier wave signal without waveform distortion and stably operate a PWM-controlled power converter in a carrier synchronization method in which the phases of a modulated wave signal and a carrier wave signal are synchronized and controlled. It is an object. [Constitution] In a PWM converter 1 for controlling a carrier wave signal and a modulated wave signal in synchronization with each other, the carrier wave signal is an AC power supply 3
Voltage signal Vd * for controlling the synchronous signal θ of the above and the input voltage voltage vector of the PWM converter 1 on the rotational coordinate axes by d, q,
It is created based on the correction signal φ calculated from Vq *,
The filter circuit 19 removes the ripple of the correction signal φ. [Effect] The power converter can be operated efficiently and stably, and the generation amount of harmonics can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PWM-controlled power converter, and more particularly to a PW for controlling the ON / OFF of the power converter.
M controller.

[0002]

2. Description of the Related Art As a PWM control device for a power converter composed of a self-extinguishing type switch element, a so-called carrier synchronization system for controlling the phases of a modulation wave signal (sine wave) and a carrier wave signal (triangular wave) in synchronization with each other There is. Conventionally, as a carrier synchronization method of this type, as described in Japanese Patent Application Laid-Open No. 4-42780, a phase difference (φ) from a system voltage is calculated from two components Vd and Vq of a voltage for controlling d and q on a rotation coordinate axis. Calculate,
A method of correcting the phase of the carrier signal based on this value has been proposed. However, in a large capacity power converter, it is necessary to set the switching frequency low in order to reduce switching loss and snubber loss of the element. Therefore, a large amount of ripple components are included in Vd and Vq for calculating the phase difference (φ), which causes a problem that the carrier signal cannot be operated normally, but these are not mentioned at all. .

[0003]

In the above-mentioned conventional technique, d, q when the switching frequency of the power converter is set low.
The ripple component contained in the two components Vd and Vq of the shaft voltage is not taken into consideration, and finally there is a problem in operating the power converter normally.

An object of the present invention is to provide a two component V of d and q axis voltages.
Even if the ripple components are included in d and Vq, a carrier wave signal without waveform distortion is created, the phases of the modulated wave signal and the carrier wave signal are synchronized and controlled, and the generation amount of harmonics of the power converter is suppressed. An object of the present invention is to provide a PWM control device capable of doing the above.

[0005]

The above object is to provide a power converter connected to an AC power supply via a reactor, a means for generating a phase signal synchronized with the voltage of the AC power supply, the phase signal and a correction signal. Means for outputting a carrier wave signal based on the above, a means for comparing the carrier wave signal and a modulated wave signal, and controlling the power converter on and off, and an input voltage vector of the power converter on a rotating coordinate axis. In the PWM control device having means for outputting a modulated wave signal from the voltage commands Vd *, Vq * and means for calculating a correction signal from the voltage commands Vd *, Vq *, ripples are removed from the output of the correction signal. It can be realized by providing means.

[0006]

The carrier signal is created based on the phase signal synchronized with the voltage of the AC power source and the correction signal calculated from the voltage commands Vd * and Vq * for controlling the input voltage vector of the power converter d and q. If the ripple component is included in the waveform, the waveform of the carrier signal is distorted, and normal operation cannot be performed, so that the harmonics of the power converter increase. At worst, the power converter may not operate normally. In order to prevent this, ripples can be removed by the operation of the filter as described above, and the amount of harmonics generated in the power converter can be suppressed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. The PWM converter 1 is composed of a circuit in which diodes are connected in antiparallel to each bridge-connected self-extinguishing type switch element. The PWM converter 1 is connected to an AC power source 3 via an AC reactor 2 and a capacitor 4 is provided on a DC output side. It is connected. The load 5 is a load of the PWM converter 1. The voltage detection circuit 6 detects the DC voltage Ed of the PWM converter 1. The voltage control circuit 7 calculates the deviation between the DC voltage Ed detected by the voltage detection circuit 6 and the voltage command Ed *, and outputs the active current command Iq *. The sine wave generation circuit 9 outputs a sin component and a cos component which are reference signals for coordinate conversion based on the synchronization signal (phase signal) θ of the AC power supply 3 detected by the phase detection circuit 8. The current detection circuit 11 uses the alternating current detected by the current detector 10 and the reference signal of the sine wave generation circuit 9 to determine the active current Iq and reactive current Iq of the alternating current.
d is separated and output. The active current control circuit 12 calculates the deviation between the active current command Iq * and the active current Iq, and q
The axis voltage command Vq * is calculated. On the other hand, the reactive current control circuit 13 calculates the deviation between the reactive current command Id * and the reactive current Id to calculate the d-axis voltage command Vd *. Further, the 2-phase / 3-phase conversion circuit 14 is based on the reference signal of the sine wave generation circuit 9 and based on the d, q-axis voltage commands Vd *, Vq *, the three-phase modulated wave signals (AC voltage commands) eR *, eS *. , ET * are output. The adder circuit 15 adds a synchronization signal θ of the phase detection circuit 8 and an output signal φF of a filter circuit 19 described later, and outputs a phase reference signal θ *. The carrier wave generation circuit 16 outputs a carrier wave signal (triangular wave carrier signal) synchronized with the phase reference signal θ *. The PWM control circuit 17 uses the modulated wave signal eR
*, ES *, eT * are compared with the carrier wave signal, and the switching command sw is output to the self-turn-off switch element of the PWM converter 1. Further, the phase calculation circuit 18 changes the phase from the two components of the dq axis voltage commands Vd * and Vq * with respect to the synchronization signal θ, that is, the correction signal φ [φ = arctan (Vq
* / Vd *)] and is added as an input signal φF of the adder circuit 15 through the filter circuit 19.

The basic operation of this embodiment is as follows. The PWM converter 1 for converting AC voltage to DC is most suitable as a power supply for an inverter because it can control the power factor of the power supply voltage to 1.0 and can perform forward conversion and reverse conversion freely. The method is also well known as described in Japanese Patent Application Laid-Open No. 4-42780, and its explanation is omitted.

The switching command sw of the PWM converter 1 is PWM based on the carrier wave signal and the modulated wave signal.
The carrier signal is generated by comparison in the control circuit 17, but at this time, the carrier signal is a signal synchronized with the phase reference signal θ * which is the output signal of the adding circuit 15. On the other hand, the correction signal φ calculated by the phase calculation circuit 18 is applied to the filter circuit 19
The ripple component contained in the signal is removed by the first-order lag element and added to the adder circuit 15 as the correction signal φF. Therefore, the output of the adder circuit 15 becomes the phase reference signal θ * obtained by adding the correction signal φF to the synchronization signal θ, and becomes a signal synchronized with the modulated wave signal. Therefore, the carrier wave signal and the modulated wave signal output from the carrier wave generation circuit 16 can always be operated in synchronization. Although the first-order lag element has been described as the filter circuit 19, another filter element can be used as long as it can remove the ripple component. Next, the effect of the embodiment of FIG. 1 will be described with reference to FIGS. 2 shows the case where the filter circuit 19 is not added to the output of the phase calculation circuit 18, and FIG.
8 shows operation waveforms when the filter circuit 19 is added to the output of FIG. If the filter circuit 19 is not added, the correction signal φ contains a large amount of ripples, so that the waveform of the carrier signal is distorted and a normal waveform cannot be obtained. However, when the filter circuit 19 is added, the ripple component included in the correction signal φ is removed, so that the carrier signal can be operated normally. Therefore, since the carrier wave signal synchronized with the modulated wave signal can be generated, the PWM converter 1 can be efficiently operated and can be stably operated.

As described above, since the ripple component contained in the output of the phase calculation circuit 18 is removed, the carrier signal can be operated without waveform distortion.
The converter 1 can be efficiently and stably operated, and the generation amount of harmonics can be suppressed.

FIG. 4 shows another embodiment of the present invention. The same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.
The difference from FIG. 1 lies in the advance compensation circuit 20 and the addition circuit 15. The lead compensating circuit 20 is for compensating for the delay of the filter circuit 19, and the adder circuit 15 adds the synchronizing signal θ from the phase detecting circuit 8 and the output signal φ _O from the lead compensating circuit 20 to obtain a phase reference. Output signal θ *. The correction signal φ calculated by the phase calculation circuit 18 is applied to the filter circuit 19
The delay is advanced by the compensation circuit 20 and the delay can be compensated. Therefore, since the phase reference signal θ * can operate without delay with respect to the modulated wave signal, there is an effect that carrier synchronization is performed more quickly than the above.

FIG. 5 shows another embodiment of the present invention. The same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.
The difference from FIG. 1 is that a filter circuit 25 and an adding circuit 15 are added to the outputs of the active current control circuit 12 and the reactive current control circuit 13 instead of the filter circuit 19. The band pass filter circuit 31 is a circuit for detecting the ripple component VqL * of the q-axis voltage command Vq *, and the adder circuit 3
2 is a voltage command Vq * and a band pass filter circuit 31
Output signal VqL * is added to output a q-axis voltage command Vq **. Further, the band pass filter circuit 33 is d
A circuit for detecting the ripple component VdL * of the axis voltage command Vd *, the adder circuit 34 adds the voltage command Vd * and the output signal VdL * of the band pass filter circuit 33 to obtain the d-axis voltage command Vd **. Output. On the other hand, the d, q-axis voltage commands Vq **, Vd ** are added to the ripple commands (VqL *, Vd *) with respect to the voltage commands (Vq *, Vd *) by the adding circuits 32, 34.
Since the dL *) is added so that the phases are opposite to each other, the ripple component is canceled. Therefore, the two-phase / three-phase conversion circuit 14 and the phase calculation circuit 18 can be operated based on the d, q-axis voltage commands Vq **, Vd ** that do not include the ripple component, and the same effect as described above can be obtained. Is obtained.

FIG. 6 shows another embodiment of the present invention. The same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.
The difference from FIG. 1 is notch filter circuits 35 and 36. This is for removing only the ripple components of the active current Iq and the reactive current Id of the alternating current detected by the current detection circuit 11. By removing the ripple components contained in the active current Iq and the reactive current Id, the d and q axis voltage commands Vq
Since the ripple component contained in * and Vd * decreases, the same effect as described above can be obtained. The current detection circuit 11 is used as a method of removing the ripple components of the active current Iq and the reactive current Id.
The case where the notch filter circuits 35 and 36 are added to the output side of is described, but the same applies when a band pass filter circuit is added to the input side of the current detection circuit 11 and only the fundamental wave of the power supply current is detected. The effect of is obtained.

FIG. 7 shows another embodiment of the present invention. The same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.
The difference from FIG. 1 is that a PWM inverter is applied instead of the PWM converter. PWM inverter 4
0 converts the DC voltage 41 into the AC voltage, and the AC motor 42
Is supplied with a three-phase AC voltage. The speed detector 43 detects the speed ωr of the AC motor 42. The speed control circuit 44 detects the speed ωr detected by the speed detector 43 and the speed command ωr *.
And the deviation is calculated and the active current command Iq * is output. The slip frequency calculator 45 calculates the slip frequency ωs based on the active current command Iq *. The adder 46 adds the speed ωr and the slip frequency ωs, and outputs the primary frequency ω ₁ of the AC motor 42. The conversion circuit 47 is a circuit for converting the primary frequency ω ₁ into the phase signal θ. Even when the AC inverter 42 is vector-controlled by the PWM inverter 40, the carrier signal can be normally operated by similarly removing the ripple included in the correction signal φ, so that the same effect as described above can be obtained.

[0015]

According to the present invention, by removing the ripple component contained in the output of the phase calculating circuit for calculating the correction signal φ, a carrier wave signal having no waveform distortion is created and the phase of the modulated wave signal and the carrier wave signal is generated. Since the control is performed in synchronism with each other, the power converter can be operated efficiently, and the amount of generated harmonics can be reliably suppressed.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a PWM converter device showing an embodiment of the present invention.

FIG. 2 is a diagram showing waveforms of a modulated wave signal and a carrier signal when the conventional technique is applied.

FIG. 3 is a waveform diagram showing an effect when the present invention is applied.

FIG. 4 is a circuit configuration diagram of a PWM converter device showing another embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a PWM converter device showing another embodiment of the present invention.

FIG. 6 is a circuit configuration diagram of a PWM converter device showing another embodiment of the present invention.

FIG. 7 is a circuit configuration diagram of a PWM converter device showing another embodiment of the present invention.

[Explanation of symbols]

1 ... PWM converter, 4 ... Capacitor, 7 ... Voltage control circuit, 8 ... Phase detection circuit, 9 ... Sine wave generation circuit, 11 ...
Current detection circuit, 12 ... Active current control circuit, 13 ... Reactive current control circuit, 14 ... 2-phase / 3-phase conversion circuit, 15 ... Addition circuit, 16 ... Carrier generation circuit, 17 ... PWM control circuit, 1
8 ... Phase calculation circuit, 19 ... Filter circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiko Miyazaki 7-1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory

Claims (6)

[Claims] 1. A power converter for converting an alternating current into a direct current or a direct current into an alternating current, a means for outputting a carrier signal based on a phase signal and a correction signal serving as a reference of the output of the power converter, and the carrier signal. A means for comparing the modulated wave signal and controlling ON / OFF of the power converter and an AC voltage vector of the power converter on a rotating coordinate axis so that the AC output current of the power converter has a predetermined value. Voltage command V to control
In a PWM control device comprising current control means for generating d *, Vq *, means for outputting a modulated wave signal, and means for calculating a correction signal from the voltage commands Vd *, Vq *,
A PWM control device comprising means for removing ripple included in the output of the correction signal. 2. The PWM control device according to claim 1, further comprising a first-order lag element as means for removing ripples. 3. A power converter for converting an alternating current into a direct current or a direct current into an alternating current, means for outputting a carrier signal based on a phase signal and a correction signal serving as a reference of the converter output, and the carrier signal and the modulation. Means for controlling the power converter on / off by comparing with the wave signal, and a voltage command Vd * for controlling the AC voltage vector of the power converter on the rotating coordinate axis.
In a PWM control device having means for outputting a modulated wave signal from Vq * and means for calculating a correction signal from the voltage commands Vd *, Vq *, means for removing ripple included in the output of the correction signal. And a PWM control device comprising lead element means for compensating an operation delay for eliminating the ripple. 4. The PWM control device according to claim 3, further comprising first-order lag element means as means for removing ripples. 5. A power converter for converting an alternating current into a direct current or a direct current into an alternating current, means for outputting a carrier signal based on a phase signal and a correction signal serving as a reference of the output of the power converter, and the carrier signal. Means for comparing the modulated wave signal with each other to turn on and off the power converter, means for detecting an active current Iq and a reactive current Id from an alternating current of the power converter, and a command value Iq * of the active current. And a means for outputting voltage commands Vd * and Vq * for controlling the AC voltage vector of the power converter on the rotating coordinate axis so that the detected value Iq and the reactive current Id become zero, and the voltage command Vd.
In the PWM control device having means for outputting a modulated wave from *, Vq * and means for calculating a correction signal from the voltage commands Vd *, Vq *, the voltage commands Vd *, Vq *
A PWM control device comprising a band pass filter element and an adder circuit for removing ripples included in the output of each. 6. A power converter for converting an alternating current into a direct current or a direct current into an alternating current, means for outputting a carrier wave signal based on a phase signal and a correction signal serving as a reference of the output of the power converter, and the carrier wave signal. A means for comparing the modulated wave signals to control the power converter on and off, a means for detecting an active current Iq and a reactive current Id from an input current of the power converter, and a command value Iq * of the active current. A voltage command V for controlling the AC voltage vector of the power converter on the rotating coordinate axis so that the detected values Iq match and the reactive current Id becomes zero.
means for outputting d *, Vq *, and the voltage command Vd *,
In a PWM control device having means for outputting a modulated wave signal from Vq * and means for calculating a correction signal from the voltage commands Vd *, Vq *, means for removing ripple included in the output of the correction signal. And a notch filter element means for removing ripples contained in the active current Iq and the reactive current Id.
Control device.