JPH0731156A - Controller for three-phase inverter - Google Patents

Abstract

PURPOSE:To allow high response sine wave voltage control by providing a voltage control means for subjecting the three phase voltages of a three-phase inverter to simultaneous average value control and a phase voltage control means for controlling each phase voltage of the three-phase inverter that the line voltage becomes sinusoidal. CONSTITUTION:Since the DC power supply voltage VDC fluctuates significantly in the case of a vehicle power supply a divider 37 produces a signal 1/VDC which is fed, as a feedforward signal, to the output of an amplifier 13 through an adder 35. The signal 1/VDC is multiplied by a phase reference voltage Vu at a multiplier 15 and the output voltage of the inverter is controlled constant regardless of the fluctuation of the VDC In order to compensate for voltage drop or the like, an output V40 from a voltage reference generator 40 is compared with a signal V14 obtained by subjecting the three phase voltages detected by a voltage detector 11A to full-wave rectification through a rectifier 14. The error of voltage waveform is then amplified through an amplifier 13 and added through an adder 35 thus correcting the average value of the voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase inverter that outputs a three-phase AC voltage from a DC power supply, and more particularly to a control circuit for a three-phase output inverter that performs voltage control with high-speed response.

[0002]

2. Description of the Related Art A three-phase inverter for controlling voltage has various uses, but a conventional three-phase inverter used for a constant voltage power supply for a vehicle is used.
A typical control circuit of the phase inverter is shown in FIG. In FIG. 8, the pantograph 1 receives DC power from an overhead wire (not shown), has a filter effect by the reactor 2, the capacitor 3 and the capacitor 4 so as not to send out harmonics to the overhead wire, and causes a current to flow in the rail 5 line. The voltage of the capacitor 3 is PWM-controlled by the inverter bridge 6 to be converted into a three-phase alternating current, and the winding 10 of the transformer is passed through the LC filter 8.
Enter in a.

Similarly, the voltage of the capacitor 4 is PWM-controlled by the inverter bridge 7 to be converted into a three-phase alternating current,
Input to the winding 10b of the transformer through the LC filter 9. A sinusoidal AC output voltage is obtained at the UVW terminal from the winding 10c of the converter.

The reason why the DC power supply is divided by the capacitors 3 and 4 is that the voltage rating of the element used for the inverter bridge is low.
In some cases, it is done with a ke.

The control circuit for controlling the inverter bridges 6, 7 detects the voltage between the voltage reference (DC) 12 and the AC outputs U, V, W by the transformer 11 and rectifies the three-phase full-wave output voltage by the rectifier circuit 14. The average value is compared with the average value, and the deviation is amplified by the amplifier ₁₃ to output the signal V ₁₃ . The trapezoidal waves v _tu , v _tv , and v _tw are output from the phase reference signal generator 17 according to the phase data output from the phase signal oscillator 16 having a built-in oscillator, and the output V _TU , V multiplied by the signal V ₁₃ is multiplied by the multiplier 15. _{Get TV} , V _TW . Comparing this signal and the carrier wave from the triangular wave generator 18
19, 20 and 21 are compared with each other to form a PWM signal, and the inverter bridges 6 and 7 are driven through the drive circuit 22.
The output voltage of the phase alternating current is controlled to be constant.

The outputs V _TU and V _TV of the phase reference signal generator 17 are
When the trapezoidal wave as shown in 10 (a) is used, the phase output of the PWM-controlled inverter bridge has a waveform proportional to V _TU and V _TV . Therefore, the line voltage V _UV is controlled to be a sine wave with a waveform obtained by subtracting V _TV from V _TV .

However, in such a method of controlling the average value of the output voltage, since the filters 8 and 9 form an LC resonance circuit, the gain at the resonance frequency portion is lowered to suppress the vibration. In addition, the voltage control response was slow and the waveform distortion was large.

Particularly in a vehicle power source, a flicker of the fluorescent lamp is a problem because the brake compressor and the fluorescent lamp are connected to the same power source and the inverter output voltage value and the waveform fluctuate due to the torque fluctuation of the compressor.

As a method for solving the problem, a method in which the instantaneous value control of the AC voltage is added as shown in FIG. 9 is partially adopted. It should be noted that FIG. 9 shows an example in which one inverter bridge is used.

That is, the output signals v _tu , v _tv , v _tw of the phase reference signal generator 17 are respectively added by adders 23, 24 to v _tu −.
V _tv and v _tw −v _tv are obtained, the line voltage references v _uv and v _wv are output, and the deviations from the line voltage detected by the transformer 11 are amplified to obtain v ₂₅ and v ₂₆ , respectively. In order to convert this voltage into the phase of the phase, from v ₂₅ and v _26/2 through the coefficient unit 28, v ₂₅ + v _26/2 is obtained by the adder 29 and V _TU is added by the adder 32 as the u phase correction amount.
Is added and converted into a PWM signal by the comparator 19.

Similarly, from v ₂₆ and v _25/2 via the coefficient unit 27, v ₂₆ + v _25/2 is obtained by the adder 31 as a W-phase correction component and added to V _TW by the adder 34. The - (v _25/2 + v _26/2) is added to V _TV by the adder 33 a V-phase correction amount determined by the adder 30.

Since these addition vector diagrams have a phase difference of 60 ° between V _UV and V _WV as shown in FIG. 10 (b), the relationship for converting into phase voltages of V _U , V _V , and V _W. The adders 29, 30, 31 and the coefficient units 27, 28 in FIG. 9 realize this relationship. Note that FIG. 10C is a vector diagram of the line voltage and the phase voltage. According to this method, the method of FIG. 8 is added to the control of the average voltage, and the correction of each phase is performed by detecting the deviation of the instantaneous value of the line voltage, so that a high-speed response can be achieved.

[0013]

As described above, the conventional average value control system rectifies the inverter output and performs PI control to the extent that this rectified ripple is not amplified, so that the response is slow and it is proposed to cover this. In order to instantaneously control the line voltage as described above, there is a method of amplifying the deviation of the line voltage by using the line reference sine wave voltage and performing the phase correction voltage. However, this method controls the resonance system including the LC filter, and the ratio between the resonance frequency of the filter and the frequency of the AC output is 5 to 5.
Since it is often 10 times, it is difficult to increase the control gain.

For this reason, it is necessary to make the average value control loop as fast as possible and use the AC instantaneous value control as a supplement. If the gain of the average value control loop is increased, the ripple of the rectified waveform will distort the inverter output waveform, and the effect of improving the waveform by the instantaneous value control will be reduced. As a method of controlling the line voltage, the line reference voltage is combined, the deviation from the line voltage is amplified, and the phase correction voltage is combined. Since the conversion is performed twice, an error occurs in the vector, and the waveform improving effect and the response improving effect are often deteriorated. In particular, when a waveform is converted using a calculator, the control is delayed by the conversion time and the response deteriorates. An object of the present invention is to solve the above problems and to provide a control circuit for a three-phase output inverter that is stable and has a fast control response with a sinusoidal voltage with less waveform distortion.

[0015]

According to a first aspect of the present invention, in a controller for a three-phase inverter that obtains a three-phase AC voltage from a DC power supply, a signal generating means for outputting a phase voltage reference of three phases having a constant amplitude. Voltage control means for converting the three-phase AC voltage into a DC level signal to obtain a voltage deviation from a DC level reference voltage; and multiplication means for multiplying the voltage deviation by the phase voltage reference to obtain a voltage control signal. , Phase voltage control means for obtaining a phase voltage deviation between the phase voltage of the output voltage of the three-phase inverter and the voltage control signal, and pulse width modulation of the three-phase inverter by the added value of the voltage control signal and the phase voltage deviation. PWM control means for controlling is provided.

Further, the phase voltage control means is provided with two phases, and the remaining phase is performed by the sum of the output signals of the phase voltage control means for the two phases. Further, the signal generating means outputs the three-phase phase voltage reference of the constant amplitude according to the phase signal of a constant cycle, and outputs the three-phase full-wave rectified waveform as the voltage reference of the DC level according to the phase signal. A second signal generating means is provided.

Further, there is provided a differentiating means for adding the differential value of the output signal of the second signal generating means to the output signal. According to a fifth aspect of the present invention, in a control device for a three-phase inverter that obtains a three-phase AC voltage from a DC power supply, a signal generating unit that outputs a phase voltage reference of three phases having a constant amplitude and the three-phase AC voltage are DC. Voltage control means for converting to a level signal to obtain a voltage deviation from a DC level reference voltage, multiplication means for multiplying the voltage deviation by the phase voltage reference to obtain a voltage control signal, and a phase output by the three-phase inverter Phase voltage differential value control means for obtaining a phase voltage differential value deviation between the differential value of the voltage and the differential value of the phase voltage reference, and pulse the three-phase inverter with the added value of the voltage control signal and the phase voltage differential value deviation. PWM control means for width modulation control is provided.

According to a sixth aspect of the present invention, in a control device for a three-phase inverter that obtains a three-phase AC voltage from a DC power supply, a signal generating means for outputting a phase voltage reference of three phases of constant amplitude, and the three-phase AC. Voltage control means for converting a voltage into a signal of DC level to obtain a voltage deviation from a DC level reference voltage; multiplication means for multiplying the voltage deviation by the phase voltage reference to obtain a voltage control signal; and the voltage control signal, According to the added value of the differential value of the phase voltage output by the three-phase inverter,
PWM control means for controlling pulse width modulation of the phase inverter is provided.

In any of the inventions, polar coordinate conversion means can be used as means for converting the three-phase AC voltage into a DC level signal. Further, arithmetic means for obtaining the reciprocal value of the voltage of the DC power source is provided, and the multiplying means is configured to obtain the voltage control signal by multiplying the phase voltage reference by the sum of the voltage deviation and the reciprocal value. Further, the signal generating means is configured to output a phase voltage reference of three phases having a constant amplitude and containing a third harmonic component in accordance with a phase signal having a constant cycle.

[0020]

According to the invention of claim 1, the voltage control means collectively controls the average value of the phase voltages of the three phases of the three-phase inverter, and at the same time, the phase voltage control means controls the phase voltage of each of the three-phase inverters between the lines. The voltage is controlled to be a sine wave. Further, the DC level voltage reference used in the voltage control means is a three-phase full-wave rectified waveform to suppress ripple components and perform stable average value control with high gain. In this case, a more stable average value control is performed by adding a voltage-based differential value.

In the invention corresponding to claim 5, the voltage control means collectively controls the average value of the phase voltages of the three phases of the three-phase inverter, and at the same time, the phase voltage differential value control means controls each phase voltage of the three-phase inverter. The line voltage is controlled to be a sine wave.

In the invention corresponding to claim 6, the voltage control means collectively controls the average value of the phase voltages of the three phases of the three-phase inverter, and at the same time, the differential value of the phase voltage output by the three-phase inverter is used as the voltage control signal. Stable voltage control is performed by adding.

In any of the inventions, by adding the reciprocal value of the voltage of the DC power supply to the voltage deviation, the fluctuation of the output voltage of the three-phase inverter due to the voltage fluctuation of the DC power supply can be suppressed by the feedforward control. That is, voltage V _DC of the DC power supply, when the PWM modulation rate for the output voltage of M, 3-phase inverter and V _AC, the inverse value from the relationship _{V DC · M = V AC K} / V DC ( where K is a constant ) Can be made feed-forward to prevent V _AC from being influenced by V _DC . Further, the maximum line voltage of the output of the three-phase inverter can be increased by including the third harmonic component in the phase voltage reference output by the signal generating means.

[0024]

FIG. 1 shows an embodiment of the present invention. The same parts as those in FIG. 9 are denoted by the same reference numerals and the description thereof will be omitted. In FIG.
11A is a voltage detector for detecting the phase voltage of three-phase AC,
It has a transformer for matching the phase with the phase voltage of the three-phase output of the inverter 7.

36 is a voltage detector 37 for detecting the voltage of the capacitor 4 (DC power supply), 37 is a divider for generating the reciprocal of the detected voltage, and 35 is an adder for adding the output of the divider 37 and the output of the amplifier 13. It is a vessel. 38 and 40 are signal generators that output signals of predetermined waveforms according to the phase data output from the phase signal generator 16, and have a built-in memory (ROM).

The signal generator 40 outputs a signal v ₄₀ having a three-phase full-wave rectified waveform and functions as a voltage reference generator. The phase reference signal generator 17 generates sinusoidal phase voltage references v _u , v _v , v _w , and the signal generator 38 generates a triple harmonic component v ₃ .

The multiplier 15 multiplies the output v ₃₅ of the adder ₃₅ and the outputs v _u , v _v , v _w and v ₃ of the signal generators 17 and 38, respectively, and outputs them. The adder circuits 32, 33 and 34 The voltage control signals v _Tu , v _Tv , and v _Tw each containing the third harmonic are v ₃₅ (v
_u + v ₃ ), v ₃₅ (v _v + v ₃ ), v ₃₅ (v _w + v ₃ ).
Is output.

The amplifiers 25, 26, 39 compare the phase voltage references v _u , v _v , v _w output from the signal generator 17 with the phase voltages V _U , V _V , V _W detected by the voltage detector 11A. The deviation is output as a correction signal.

The transformer 10 provided on the output side of the inverter 7 has its primary side connected to Δ in order to remove the 3n-th (n = 1, 2 ...) Harmonics. When the secondary side is connected to Y, it is possible to detect the phase voltage of the output of the inverter 7 as shown in FIG. 3 by setting the transformer of the voltage detector 11A as ΔY and the neutral point of the secondary side as the common potential. it can. The phase voltage v _u of the inverter output and the secondary V _U of the transformer of the voltage detector 11A can be detected as the same phase.

Next, pulse width modulation control (PWM control) of the inverter bridge of FIG. 1 will be described. In the triangular wave comparison PWM, between the modulation factor M and the voltage of the DC power supply is V _DC , and between the inverter phase output voltage V _AC , as described above, M = V
The relationship of _AC / V _DC is established. Therefore, the modulation factor M is M × 1
If controlled in the relationship of / V _DC , V _AC can be controlled stably without being affected by the fluctuation of V _DC . In the case of a power source of a vehicle, since the change in V _DC is large and changes abruptly, a signal of 1 / V _DC is obtained by the divider 37 and added as a feedforward signal to the output of the amplifier 13 via the adder 35. The configuration is This signal 1 / V _DC is multiplied by the phase reference voltage v _u in the adder 15, and the output voltage of the inverter is controlled forward so as to be substantially constant even if V _DC changes.

A signal obtained by full-wave rectifying the output v ₄₀ of the voltage reference generator ₄₀ and the phase voltage of the three phases detected by the voltage detector 11A by the rectifier 14 in order to compensate the control error and the voltage drop of the filter and the transformer. The error of the voltage waveform is amplified by the amplifier 13 as compared with v ₁₄ and added to the adder 35. This corrects the average value of the voltage.

As shown in FIG. 2, the output v ₁₄ of the rectifier ₁₄ is 3
It becomes a full-phase rectified waveform and contains ripples. In FIG. 1, the voltage reference v ₄₀ also outputs the same waveform as this three-phase full-wave rectified waveform from the signal generator 40, so ideal sine wave outputs are output to the U, V, and W terminals and balanced. AC component only DC component in the output of the amplifier 13 if it is is not output, the output of the multiplier _{15 v15 u, v15 v, v15} w is a sine wave, to v _15-3 other than the third harmonic Since no component is included, it is possible to output a voltage without distortion at the inverter output.

This state will be described in detail with reference to FIG.
The phase voltage references v _u and v _v are 120 ° phase-shifted waveforms, v ₃
Is the third harmonic output, and the outputs v _Tu , v of the adders 32, 33
_Tv becomes (v _u + v ₃ ) v ₃₅ and (v _v + v ₃ ) v ₃₅ .

As described above, the maximum line voltage can be increased by adding the third harmonic wave v ₃ to the phase voltage reference. This method is generally adopted, and the line voltage V _uv has a waveform obtained by subtracting (v _v + v ₃ ) from (v _u + v ₃ ).

To further improve the waveform of the sine wave, the phase voltage reference v
_{Since u} is compared with the detected voltage V _U and the error is amplified by the amplifier 25 and added to v _Tu to control the u-phase voltage waveform, an extremely good voltage waveform can be obtained. The same applies to the v phase and the w phase.

By this voltage waveform control, the error between the detected voltage v ₁₄ and the reference voltage v ₄₀ is also reduced, and the voltage control of a fast response with a good waveform can be performed. As described above, according to the present embodiment, the fluctuation of the DC power supply is controlled at high speed by feedforward, and the other fluctuations are subjected to the intermediate control between the average value and the instantaneous value by using the voltage reference similar to the rectified waveform. Even if the control gain is increased by doing so, control with less waveform distortion can be performed at high speed, and high-accuracy voltage control is performed, and at the same time, the phase voltage reference and the phase voltage are directly compared and corrected to correct the waveform with less error. It is possible to perform voltage control with good efficiency. As a result, a control circuit for a three-phase inverter without flicker is obtained.

Another embodiment of the present invention is shown in FIG. In the case of directly outputting without using a transformer on the output side of the filter 9 as in this embodiment, the voltage detector 11A has primary and secondary outputs.
It is possible to detect the phase voltage by using a transformer provided with a third (short-circuit) winding of Δ connection and the next winding as YY connection.

Also, a differentiation circuit is provided on the output side of the rectifier 14 of FIG.
41 is provided to increase the speed and stability against load fluctuations, but in that case a differential circuit 42 is also provided on the voltage reference output side to cancel the AC component due to the differentiation of the three-phase full-wave rectified waveform. It is effective for improvement.

The same operation can be performed by directly outputting a trapezoidal wave which is a line voltage of a sine wave as shown in FIG. 7A without adding the third harmonic component to the phase voltage reference. it can.

In the waveform control part, the output of the amplifier 25 is the correction amount of the u phase, the output of the amplifier 39 is the correction amount of the w phase, and the vector sum of the three phases is zero. The correction amount can be added by the adder 43 and the signal-inverted voltage can be used as the v-phase correction amount.

As shown in FIG. 7B, the voltage detector 11A is replaced with a polar coordinate converter 55 for converting the output voltage of the transformer 11 into a DC voltage that does not include ripples, and the DC voltage reference 12 It is also possible to adopt a configuration for comparing with.

Another embodiment of the present invention is shown in FIG. As shown in this embodiment, the outputs v _u , v of the phase reference signal generator 17
Amplifiers _v and v _w via differentiating circuits 44, 46 and 46, respectively.
Inputs 25, 26 and 39 are used as the phase current reference of the circuit of the filter capacitor 9b. The phase current of the filter capacitor 9b is detected by the converters 49a, 49b, 49c and the amplifiers 25, 26, 39 are detected.
To the comparator 19,
By adding to 20 and 21, respectively, the phase current of the capacitor is controlled to be a sine wave.

Since the control loop of the capacitor current is a first-order lag circuit, it is very stable as compared with the voltage control loop of the second-order lag circuit, and the gain of the phase current control loop of the capacitor can be increased. is there.

By controlling the phase current of this capacitor, the response of the control loop for the average value voltage can be delayed, so that the voltage reference 12 can be a constant DC voltage. The signals of the differentiating circuits 44, 45, 46 are v _u , v _v , v
Amplifiers 25, 25, 39 with a signal that advances the phase voltage reference of _w by 90 °
Although the example of adding to the comparators 19, 20, and 21 via the above is shown, the signals of the differentiating circuits 44, 45, and 46 consider the polarity and adder circuits
May be added to 32, 33, 34. Since the addition of this signal is the addition of a sine wave, it has the effect of slightly advancing the phases of the voltages v15 _u , v15 _v , and v15 _w .
If 45 and 46 are omitted and the phase current of the capacitor is used as a feedback signal for stabilization, the phase of the output voltage will be slightly delayed and can be implemented without any practical problems, and the differentiation circuits 44, 45 and 46 are omitted. It is possible.

Further, since the feedback of the phase current of the filter capacitor 9b is equivalent to the differentiation of the output phase voltage, the phase voltage is detected by the transformer 11 as shown in FIG. It is also possible to feed back to the comparators 19, 20, 21.

In FIG. 6, the phase voltage reference v _u is shown in FIG.
It is also possible to directly output a signal waveform including a trapezoidal wave as shown in FIG. 2 and a third harmonic wave shown in FIG. Further, as described above, it is possible to omit the phase voltage reference differentiating circuit, but when the loop gain of the DC average value control is set relatively high, the phase of the voltage reference output v ₄₀ can be omitted. A faster response can be obtained by correcting the output and then adding the phase delay of the output waveform by the control and filter. The present invention described above can be implemented using a computer, and can be implemented using various combinations.

[0047]

According to the first aspect of the present invention, the average value of the phase voltages of the three phases of the three-phase inverter is collectively controlled, and at the same time, each phase voltage is controlled for each phase so as to be a sine wave. Therefore, it is possible to perform sine wave voltage control with fast response. In addition, the influence of the ripple component can be suppressed and stable average value control can be performed with a high gain, so that a control device for a three-phase inverter with good control performance can be obtained.

According to the fifth aspect of the invention, the average value of the phase voltages of the three phases of the three-phase inverter is collectively controlled, and at the same time, the rate of change is controlled for each phase so that each phase voltage becomes a sine wave. This makes it possible to perform sinusoidal voltage control with a fast response, and a control device for a three-phase inverter with good control performance can be obtained.

According to the sixth aspect of the present invention, the average value of the phase voltages of the three phases of the three-phase inverter is collectively controlled, and at the same time, the differential value of each phase voltage is added to the voltage control signal to obtain a stable average. Value control can be performed, and a control device for a three-phase inverter having a simple structure can be obtained.

Further, in any of the inventions, the feedforward control can be performed so as to suppress the fluctuation of the output voltage of the three-phase inverter due to the voltage fluctuation of the DC power supply, and the third harmonic wave is used as the phase voltage reference. Including ingredients 3
It is possible to provide a control device for a three-phase inverter that increases the maximum line voltage of the output of the phase inverter and has good conversion efficiency.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment corresponding to claims 1, 3, 9, and 10 of the present invention.

FIG. 2 is a waveform diagram for explaining a main part of FIG.

FIG. 3 is a vector diagram for explaining the voltage detector 11A of FIG.

FIG. 4 is a configuration diagram of an embodiment corresponding to claims 2 and 4 of the present invention.

FIG. 5 is a configuration diagram of an embodiment corresponding to claims 5, 7, and 10 of the present invention.

FIG. 6 is a configuration diagram of an embodiment corresponding to claim 6 of the present invention.

7 (a) is a waveform diagram for explaining the operation of the phase reference signal generator 17 used in the present invention, and (b) is a claim 8 of the present invention.
Configuration diagram of the main part of the embodiment corresponding to

FIG. 8 is a block diagram of a conventional device

FIG. 9 is another configuration diagram of a conventional device.

FIG. 10 is a diagram for explaining the operation of the conventional device.

[Explanation of symbols]

4 ... Capacitor, 7 ... Inverter bridge, 9 ... Filter, 10 ... Transformer, 11A ... Voltage detector, 12 ... Voltage reference, 13
... Amplifier, 14 ... Rectifier circuit, 15 ... Multiplier, 16 ... Phase signal generator, 17 ... Phase reference signal generator, 18 ... Three-phase wave generator, 19,
20, 21 ... Comparator, 22 ... Driving circuit, 31, 32, 33, 3
4, 35, 43 ... Adder, 25, 26, 39 ... Amplifier, 36 ... Voltage detector, 37 ... Divider, 38 ... Triple frequency generator, 40 ... Signal generator, 41, 42, 44, 45 , 46, 50, 51, 52 ... Differentiator, 49 ... Current transformer, 55 ... Polar coordinate converter.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshishi Nomura No. 1 Toshiba-cho, Fuchu-shi, Tokyo Toshiba Corporation Fuchu factory

Claims (10)

[Claims] 1. A controller for a three-phase inverter that obtains a three-phase AC voltage from a DC power supply, a signal generating means for outputting a three-phase phase voltage reference of a constant amplitude, and the three-phase AC voltage into a DC level signal. Voltage control means for converting and obtaining a voltage deviation from a DC level reference voltage, multiplication means for obtaining the voltage control signal by multiplying the voltage deviation by the phase voltage reference, phase voltage of the output voltage of the three-phase inverter and A phase voltage control means for obtaining a phase voltage deviation from the voltage control signal and a PWM control means for performing pulse width modulation control of the three-phase inverter on the basis of a sum of the voltage control signal and the phase voltage deviation are provided. Three-phase inverter control device. 2. The control device for a three-phase inverter according to claim 1, wherein the phase voltage control means includes two phases, and the remaining phases are sums of output signals of the phase voltage control means for the two phases. A control device for a three-phase inverter, which is characterized by performing. 3. The control device for a three-phase inverter according to claim 1, wherein the signal generating means outputs a phase voltage reference of the three phases having the constant amplitude in accordance with a phase signal having a constant cycle, and outputs the phase signal to the phase signal. Accordingly, the control device for the three-phase inverter is provided with the second signal generating means for outputting the three-phase full-wave rectified waveform as the voltage reference of the DC level. 4. The three-phase inverter control device according to claim 3, further comprising: differentiating means for adding a differential value of the output signal of the second signal generating means to the output signal. Inverter control device. 5. A control device of a three-phase inverter for obtaining a three-phase AC voltage from a DC power supply, a signal generating means for outputting a three-phase phase voltage reference of constant amplitude, and the three-phase AC voltage into a DC level signal. Voltage control means for converting and obtaining a voltage deviation from the DC level reference voltage, multiplication means for multiplying the voltage deviation by the phase voltage reference to obtain a voltage control signal, and differential value of the phase voltage output by the three-phase inverter. And a phase voltage differential value control means for obtaining a phase voltage differential value deviation between the differential value of the phase voltage reference and the phase voltage reference differential value, and pulse width modulation control of the three-phase inverter by the added value of the voltage control signal and the phase voltage differential value deviation. A control device for a three-phase inverter, which is provided with PWM control means. 6. A controller for a three-phase inverter for obtaining a three-phase AC voltage from a DC power supply, a signal generating means for outputting a three-phase phase voltage reference of constant amplitude, and the three-phase AC voltage into a DC level signal. The voltage control means for converting and obtaining the voltage deviation from the DC level reference voltage, the multiplication means for multiplying the voltage deviation by the phase voltage reference to obtain the voltage control signal, the voltage control signal and the three-phase inverter output. A control device for a three-phase inverter, comprising PWM control means for performing pulse width modulation control on the three-phase inverter according to an added value of differential values of the phase voltage. 7. The control device for a three-phase inverter according to claim 5, wherein the output side of the three-phase inverter is provided as a differential value of a phase voltage of an output voltage of the three-phase inverter. A control device for a three-phase inverter, which uses a detection signal of a current flowing through the filter capacitor. 8. The control device for a three-phase inverter according to any one of claims 1, 5, and 6, wherein polar coordinate conversion means is used as means for converting the three-phase AC voltage into a DC level signal. A control device for a three-phase inverter, characterized in that 9. The control device for a three-phase inverter according to claim 1, claim 5, or claim 6, wherein arithmetic means for obtaining an inverse value of the voltage of the DC power supply is provided, and the multiplier means A control device for a three-phase inverter, wherein a voltage control signal is obtained by multiplying a sum of a voltage deviation and the reciprocal value with the phase voltage reference. 10. The control device for a three-phase inverter according to any one of claims 1, 5 and 6, wherein the signal generating means generates a third harmonic component in accordance with a phase signal having a constant cycle. A control device for a three-phase inverter, which outputs a phase voltage reference of three phases having a constant amplitude including.