JP3620755B2 - Inverter control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inverter for supplying a three-phase AC voltage to a load from a DC power source or a DC voltage obtained from an AC power source, and more particularly to an inverter device having an improved modulation system of its control unit. is there.
[0002]
[Prior art]
Generally, a power converter such as an electric motor drive device or an uninterruptible power supply (so-called UPS) obtains a DC voltage from an AC power supply voltage by a converter, and converts it again to an AC voltage having a desired frequency by an inverter. Supplying power to the load.
At this time, the output AC voltage is preferably a waveform with as little distortion as possible.
In an electric motor drive device, harmonics are not preferable because they generate reverse torque or cause torque ripple.
In a UPS in which the output voltage waveform is desired to be a sine wave, the inclusion of harmonic distortion in the inverter increases the duty of the filter circuit and hinders downsizing of the apparatus.
In UPS, a storage battery is used as a DC power source in the event of a commercial power failure. In order to use the storage battery effectively, it is possible to output a high-quality power and a voltage waveform with little distortion, as well as stable operation even with large DC voltage fluctuations from the equal charge voltage or floating charge voltage to the end voltage. There is a need to.
[0003]
FIG. 5 shows a conventional example of an inverter device applied to UPS. 1 is a three-phase AC power source, 2 is a converter unit, 3 is an inverter unit, 4 is a filter unit, 5 is a load, 6 Is a control unit.
That is, the converter unit 2 includes an AC power source 1 and a converter circuit 21 made of a power semiconductor element that performs AC-DC conversion, a storage battery 22 connected in parallel to the converter circuit 21, and a DC smoothing capacitor 23. Become.
The inverter unit 3 is composed of an inverter circuit 31 and a current detector 32 made of a power semiconductor element controlled by the control unit 6 here.
The filter unit 4 includes an output transformer 41, an AC reactor 42, and a capacitor 43, and supplies power to the load 5.
The control unit 6 includes a voltage / current control unit including a voltage control unit 61 and a current control unit 63, a waveform generation unit 62, a carrier wave generator 64, a PWM generation unit 65, and a gate amplification unit 66. This operation is as follows.
[0004]
In the voltage control unit 61 of the control unit 6, the voltage detection circuit 612 detects the effective value or average value of the three-phase AC output voltage of the UPS.
In the voltage control unit 61, the difference between the output voltage setting unit 611 output and the voltage detection circuit 612 output is calculated and amplified by the adder / subtractor 63 and the operational amplifier 64, and an output current command Io * is obtained to the current control unit 63. Output.
The reference sine wave generator 621 in the waveform generation unit 62 outputs three reference sine wave waveforms Su, Sv, Sw forming a three-phase alternating current to the current control unit 63.
In the current control unit 63, the multiplier 631 multiplies each of the three reference sine wave waveforms Su, Sv, and Sw by the output current command Io *, and the amplitude is the output current command and forms a three-phase alternating current. An inverter current command Iu *, Iv *, Iw * having a sine wave waveform for each phase is generated.
An adder / subtractor 632 and an operational amplifier 633 compute and amplify errors between the inverter current commands Iu *, Iv *, Iw * and the respective phase inverter currents Iu, Iv, Iw obtained from the current detector 32, Inverter voltage commands Viu *, Viv *, and Viw * are generated.
The PWM generator 65 compares the inverter current commands Iu *, Iv *, Iw * with the carrier wave TW from the carrier wave generator 64 in the comparator portion, and the PWM waveforms PWu, PWv, PWw is output.
This PWM waveform is sent to each power semiconductor element of the inverter circuit 31 via the gate amplifying unit 66. Therefore, the UPS generates a three-phase sine wave AC voltage.
[0005]
In this type of inverter device, the harmonics included in the inverter output voltage include a carrier wave and a sideband wave based on the carrier wave and the fundamental wave in addition to the fundamental wave based on the reference sine wave.
Since the sideband is close to the frequency of the carrier wave, it can be removed with a relatively small filter circuit.
On the other hand, the fundamental wave appears in proportion to the magnitude of the sine wave when the inverter voltage command is a sine wave waveform and the peak value is less than or equal to the peak value of the carrier wave, that is, when the modulation factor is 1 or less. .
However, when the peak value of the sine wave exceeds the peak value of the carrier wave, that is, when the modulation rate exceeds 1, the fundamental wave does not appear linearly with respect to the magnitude of the sine wave. , 5, 7, 9, 11 and so on appear.
A filter circuit for removing these low-order harmonics becomes large.
In addition, the fact that the appearance of the fundamental wave changes with the modulation factor of 1 as a boundary means that the gain of the output voltage with respect to the sine wave changes, and this is a factor that hinders stable control in terms of control. Become.
Furthermore, when the modulation factor is near 1, the PWM modulated pulse width becomes very short, the response of the power semiconductor element and the gate circuit cannot follow the pulse width, and the output waveform of the inverter device is not constant, It causes distortion and causes instability of control.
[0006]
As described above, the control with a modulation rate exceeding 1 has many problems from the viewpoint of the occurrence of low-order harmonic distortion in the output waveform and further from the viewpoint of control.
When the upper limit of the modulation rate is limited to 1 or less, the relationship between the DC voltage Vdc and the fundamental voltage Vac of the output AC voltage is limited as follows.
Vac <{Vdc · (3/2) to the (1/2) th power} /2=0.612 Vdc (1)
Therefore, when the DC voltage is determined, the range in which a sine wave voltage without low-order harmonic distortion can be output is also limited to Expression (1).
[0007]
[Problems to be solved by the invention]
Thus, in the prior art, when the modulation rate exceeds 1, low-order harmonics are generated in the inverter output, or when the modulation rate is near 1, the inverter element is not turned on / off. It became a rule, and it inhibited stable control or generated distortion.
If the modulation rate is limited to 1 or less, the range of output voltage is narrowed.
[0008]
Therefore, the object of the present invention is to obtain a higher output voltage with a lower modulation degree, and to obtain a special inverter that can obtain a wider range of AC voltage than the DC voltage without waveform distortion or unstable control. -Providing a data control device;
[0009]
[Means for Solving the Problems]
The present invention has been made in view of the above points, and is configured as follows. That is,
First, an inverter unit that converts a DC voltage into a three-phase AC voltage, a voltage current control part that performs an operation for controlling the AC voltage and AC current, and a PWM waveform corresponding to the output of the voltage current control part are generated. And an inverter control device that controls an AC voltage and an AC current by providing a PWM generator output to the inverter unit, and is synchronized with a three-phase AC voltage. A bias means for obtaining a first bias waveform obtained by limiting the head of the three-phase sine wave and adding / subtracting the amount reduced by the limit operation to the other two-phase sine wave is provided. Is added to the PWM generator.
Second, in place of the first bias waveform, the head of the three-phase sine wave synchronized with the three-phase AC voltage is limited, and the amount reduced by the limit operation is added to or subtracted from the other two-phase sine wave. Is a second bias waveform obtained by multiplying an AC voltage or a DC voltage or a coefficient corresponding to both the AC voltage and the DC voltage.
Third, the limit value of the head of the three-phase sine wave is set to be less than 1 and 0.866 (the value of the electrical angle of the sine wave of 60 degrees) or more.
[0010]
By such a solution, the amplitude of the reference bias waveform of each of the three phases is limited to 0.866 times (= sin 60 °) of the sine wave, and thus appears in the voltage / current control partial output of the control unit in the prior art. Compared with the inverter voltage command, the maximum value of the bias waveform is suppressed by about 13%, and it is possible to control over a wide range of DC voltage and AC output voltage without overmodulation.
Therefore, the pulse width of the PWM waveform is widened, the operation of the power semiconductor element and the gate circuit is stabilized, and the output and control can be stabilized.
Here, since the three-phase bias waveform is a waveform with a flat head, the voltage of each phase viewed from the neutral point of the power supply voltage has a flat waveform at the top and does not become a sine wave. Since the waveform of the difference between them is a sine wave equivalent to the output of the conventional voltage / current control unit, the line voltage becomes a sine wave and does not impair the distortion of the waveform.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Specifically, it comprises bias means provided in the waveform generation portion of the control section, and addition / subtraction means for taking the sum of the bias means output and the voltage / current control portion output of the control section.
The bias means limits the waveform of the phase that is the maximum of the sine wave to three reference sine waves to 0.866 times the peak value (= sin 60 °), and the waveform of the maximum phase is 0. 0. A reference bias waveform obtained by adding and subtracting the portion exceeding 866 times from the other two-phase reference sine waveforms is obtained.
This will be described in detail with reference to the drawings of the embodiments.
[0012]
FIG. 1 shows an example when applied to a UPS according to the present invention, similar to FIG. 5, where 6 ′ is a control unit.
The control unit 6 ′ includes a voltage control unit 61 ′, a waveform generation unit 62 ′, a current control unit 63 ′, a carrier wave generator 64 ′, a PWM generation unit 65 ′, a gate amplification unit 66 ′, and an adder / subtractor 67 ′. .
That is, in contrast to the control unit 6 shown in FIG. 5, the control unit 6 ′ is configured by adding a bias circuit 62B ′ and an adder / subtractor 67 ′ in the waveform generating unit 62 ′.
Further, in the bias circuit 62B ′, 622 ′ is a reference bias waveform generator,
623 ′ is a bias modulation factor calculator, and 624 ′ is a multiplier.
[0013]
In the bias circuit 62B ′, the reference bias waveform generator 622 ′ adds the processing described later to the input of the reference sine wave waveforms Su, Sv, Sw output from the reference sine wave generator 621 ′, thereby generating the reference bias waveform Sbu, SbV and SbW are generated.
This will be described with reference to FIG.
2 shows an example of the output of the reference sine wave generator and the reference bias waveform generator of FIG. 1, where Su, Sv, Sw are reference sine wave waveforms of the reference sine wave generator 621 ′, and Sbu, SbV, SbW are reference Bias waveform generator 622 ′ output reference bias waveform, Te is a period.
That is, in the illustrated period Te, the reference sine wave waveform Su has the largest absolute value compared to the other reference sine wave waveforms Sv and Sw.
Here, the reference bias waveform Sbu is constant at 0.866 (= sin 60 °) during a period Te of 60 degrees where the reference sine wave waveform Su has the largest absolute value.
Further, the reference bias waveforms SbV and SbW are decreased (increased in absolute value) from the reference sine wave waveforms Sv and Sw by the amount that the reference bias waveform Sbu is lower than the reference sine wave waveform Su during this period Te.
This is because the reference bias waveform of the phase of the reference sine wave waveform having the maximum absolute value is fixed to 0.866 during the other 60 ° periods, and the reference bias waveform and the reference sine wave of the phase are fixed to 0.866. A reference bias waveform is obtained by adding or subtracting the difference from the waveform from another two-phase reference sine wave waveform.
Such a reference bias waveform can be realized by a limiter circuit or an addition / subtraction circuit using an electronic circuit. However, a control circuit using a microcomputer can be easily realized by providing a memory table.
[0014]
In the bias circuit 62B ′, the bias modulation factor calculator 623 ′ calculates the bias modulation factor Kb from the DC voltage Vdc and the output voltage command V * output from the output voltage setter 611 ′. Specifically, the bias modulation factor Kb at which the output AC voltage and the DC voltage are balanced from the effective value Vrms (or average value) of the output AC voltage and the DC voltage Vdc is proportional to (Kb = Vrms / Vdc). Value.
The multiplier 624 ′ takes the product of the reference bias waveforms Sbu, SbV, SbW and the bias modulation factor Kb, and outputs the bias waveforms Vbu *, Vbv *, Vbw *.
The bias waveforms Vbu *, Vbv *, and Vbw * have the same shape as the reference bias waveforms Sbu, SbV, and SbW, and have peak values that are 0.866 times the bias modulation factor Kb.
[0015]
Further, in FIG. 1, the adder / subtractor 67 ′ includes bias waveforms Vbu *, Vbv *, Vbw * output from the bias circuit 62B ′, and inverter voltage commands Viu *, Viv output from the current controller 63 ′ of the voltage / current controller. The two inputs * and Viw * are added, and the sum is given to the PWM generator 65 'as an inverter voltage command Vu *, Vv *, Vw *.
The PWM generator 65 'generates a PWM waveform by comparing the output of the adder / subtractor 67' and the output of the carrier wave generator 64 ', and the inverter circuit 31 is passed through the gate amplifier 66' by the PWM waveform. To drive.
[0016]
In such a configuration, since the bias waveforms Vbu *, Vbv *, Vbw * have a modulation rate for outputting the output AC voltage commanded from the DC voltage Vdc by the output voltage setting device 611 ′, the inverter of the output of the current control unit 63 ′ is used. -The voltage commands Viu *, Viv *, and Viw * need only control the voltage drop generated in the filter unit 4 by the inverter output current to be controlled, and the amplitude of the voltage / current control unit output is relative to the bias waveform. Becomes extremely small, and the degree of modulation is almost determined by the bias waveform.
Further, the reference bias waveform and the bias waveform have a peak value of 13% lower than that of the conventional voltage / current control unit output, and the difference between the three-phase reference bias waveform and the bias waveform is a sine wave having a peak value of 100%. Therefore, the conventional voltage is output as the line voltage.
That is, a conventional line voltage can be output with a modulation factor 13% lower than that of the prior art, and the line voltage waveform is maintained as a sine wave. This means that an AC line voltage that is 13% higher than the conventional voltage can be output without distortion at the same DC voltage.
[0017]
Such a control unit is based on the case where a loop for controlling the inverter output current and voltage is configured by the voltage / current control unit. It can be applied to a control circuit configured to match the command, or a control circuit having a voltage control loop and an AC voltage matched to the voltage command. It can be applied regardless of the shape and generating means.
Next, examples of FIGS. 3 and 4 are shown.
[0018]
As a power supply compensation device, an active filter (hereinafter referred to as AF) is commonly used.
The AF is connected in parallel to the load, and basically detects the distorted current component from the distorted current waveform generated by the load, generates the distorted current component and supplies it to the load, so that the power source has no distortion. Only the wave current flows.
FIG. 3 shows an example when applied to AF according to the present invention, where 7 is an AC power source, 8 is a load, 9 is AF, and 10 is a control unit for controlling AF.
[0019]
In FIG. 3, a load 8 that generates a distorted current is connected to an AC power source 7, and an AF 9 is connected in parallel to the load 8 in the system of the AC power source 7.
In AF9, 91 is a converter circuit, 92 is a capacitor provided on the DC side of the converter circuit 91, 93 is an AC reactor provided on the input side of the converter circuit 91, and 94 and 95 are load current detections. And an AF current detector.
In the control unit 10, 101 is a voltage control unit, 102 is a waveform generation unit, 103 is a current control unit, 104 is a carrier wave generator, 105 is a PWM generation unit, 106 is a gate amplification unit, and 107 is an adder / subtracter. Further, in the waveform generation unit 102, reference numeral 102B denotes a bias circuit.
Here, since the main circuit connection configuration in FIG. 3 is well known, the description thereof is omitted.
That is, in the control unit 10, the voltage / current control unit includes a voltage control unit 101 and a current control unit 103, the waveform generation unit 102 includes a reference sine wave generator 1021 and a bias circuit 102B, and includes an adder / subtractor 107. It consists of.
[0020]
In the voltage control unit 101, the adder / subtractor 1013 and the operational amplifier 1014 calculate and amplifies the difference between the output of the AF DC output voltage setting unit 1011 and the AF DC voltage, and outputs a DC current command Id *.
The reference sine wave generator 1021 of the waveform generator 102 outputs three reference sine wave waveforms Sr, Ss, St that form a three-phase alternating current synchronized with the power supply voltage.
The bias circuit 102B is used in the same way as the bias circuit 62B ′ shown in FIG.
In the bias circuit 102B, the reference bias waveform generator 1022 limits the reference bias waveform of the phase in which the maximum value appears from the reference sine wave waveform forming the three-phase alternating current to 0.866 times the peak value of the reference sine wave. In addition, reference bias waveforms Sbr, Sbs, and Sbt are obtained by adding and subtracting the amount reduced by the limitation to the other two-phase reference sine waves.
The bias modulation factor calculator 1023 calculates a bias modulation factor Kbc that balances the power supply voltage and the AF DC voltage from the power supply voltages Vr, Vs, Vt and Vd * of the output voltage setting unit 1011 output.
Multiplier 1024 multiplies reference bias waveforms Sbr, Sbs, Sbt and bias modulation factor Kbc to obtain bias waveforms Vbr *, Vbs *, Vbt *.
[0021]
In the current control unit 103, the multiplier 1031 multiplies the DC current command Id * output from the voltage control unit 101 by the three reference sine wave waveforms Sr, Ss, St, and three current commands Idr for each phase. *, Ids *, Idt * are obtained. This current command is a signal necessary for controlling the AF DC voltage to be constant.
The harmonic detector 1034 detects only the harmonic current from the current of the load 8 detected by the load current detector 94, and generates harmonic correction commands Ihr *, Ihs *, and Iht *.
The adder / subtractor 1035 adds the current commands Idr *, Ids *, Idt * and the harmonic correction commands Ihr *, Ihs *, Iht * to generate the alternating current commands Icr *, Ics *, Ict *. The adder / subtractor 1032 and the operational amplifier 1033 obtain error amplification between the AC current commands Icr *, Ics *, Ict * and the output of the AF current detector 95, and output the voltage commands Vir *, Vis *, Vit *.
[0022]
Then, the adder / subtractor 107 superimposes the voltage commands Vir *, Vis *, and Vit * on the bias waveforms Vbr *, Vbs *, and Vbt * to obtain converter voltage commands Vr *, Vr *, and Vr * for each phase. It is sent to the PWM generator 105.
This is further compared with the carrier wave TW from the carrier wave generator 104 by the PWM generator 105.
Therefore, the AF converter circuit 91 can be driven by the output of the PWM generator 105 via the gate amplifier 106.
Thus, the power supply current of the AF is controlled to a current obtained by superimposing the harmonic current flowing in the load 8 in addition to the current for making the voltage of the capacitor 92 constant. Therefore, harmonics do not flow through the AC power supply 7 due to the supply of the harmonic compensation current to the load 8.
[0023]
Thus, also in the example of FIG. 3, the voltage command Vir *, Vis *, Vit of the voltage / current control unit output is made to be the AC reactor 93 due to the distorted current generated by the load 8 by the function of the bias waveform obtained by the bias circuit 102B. Thus, the modulation rate is substantially determined by the bias waveforms Vbr *, Vbs *, and Vbt *.
In addition, the bias waveforms Vbr *, Vbs *, and Vbt * are waveforms that can generate a necessary line voltage at a modulation rate 13% lower than that of the sine wave signal as described above. Can be controlled without generating distortion.
[0024]
FIG. 4 shows another example when applied to the UPS according to the present invention, similar to FIG. 1, wherein 6 ″ is a control unit.
The control unit 6 ″ includes a voltage control unit 61 ″, a waveform generation unit 62 ″, a carrier wave generator 64 ″, a PWM generation unit 65 ″, a gate amplification unit 66 ″, and an adder / subtractor 67 ″.
That is, in the control unit 6 ″, the voltage / current control unit is configured only by the voltage control unit 61 ″ and does not have the current control unit.
Further, a bias circuit 62B ″ and an adder / subtractor 67 ″ in the waveform generating section 62 ″ are added.
[0025]
The voltage control unit 61 ″ includes an output voltage setting unit 611 ″, a multiplier 631 ″, a notch filter 612 ″, an adder / subtractor 613 ″, and an operational amplifier 614 ″.
The multiplier 631 ″ outputs three reference sine wave waveforms Su which are output from the output voltage command V * of the output voltage setter 611 ″ and the reference sine wave generator 621 ″ of the waveform generator 62 ″ to form a three-phase alternating current. , Sv, and Sw, and outputs AC output waveform commands Su *, Sv *, and Sw *.
The adder / subtractor 613 ″ and the operational amplifier 614 ″ perform error calculation between the AC output waveform commands Su *, Sv *, Sw * and the output voltages Vu, Vv, Vw detected via the notch filter 612 ″ to obtain a voltage deviation. Vdu, Vdv, Vdw are obtained.
The TCH filter 612 ″ is provided to prevent resonance of the voltage control system and has a characteristic of attenuating the resonance frequency of the voltage control system.
[0026]
As in FIG. 1, the sum of the bias waveforms Vbu *, Vbv *, Vbw * from the bias circuit 62B ″ of the waveform generator 62 ″ and the voltage deviations Vdu, Vdv, Vdw from the voltage controller 61 ″ Obtained by the adder / subtractor 67 "and sent to the PWM generator 65".
In this way, the deviation between the AC output waveform commands Su *, Sv *, Sw * and the output voltage obtained by the voltage control unit is superimposed on the bias waveforms Vbu *, Vbv *, Vbw *. .
[0027]
As described above, when the voltage / current control unit has a minor loop for controlling the AC voltage and further controlling the AC current, the voltage / current control unit has a loop for controlling the DC voltage and further controls the AC current. An example of voltage control loop only is shown.
Thus, the present invention is not limited to the above case, and in power conversion between an AC power source and a DC power source, a current control loop and a voltage control loop are internally provided to control the current to an arbitrary shape. Applicable to the case.
That is, with respect to the three reference sine wave waveform signals forming the three-phase alternating current, the phase value at which the maximum value appears is limited to 0.866 times the peak value of the reference sine wave, and the limit is lowered. The reference bias waveform is obtained by adding or subtracting the calculated amount to the other two phases, and the voltage control is applied to the bias command in which the amplitude of the reference bias waveform is changed from the DC voltage or AC voltage or both according to the calculated bias modulation rate. The PWM signal is obtained by a signal in which the output of the loop or current control loop is superimposed.
Furthermore, although the case where the peak value of the reference bias waveform is 0.866 times (= sin 60 °) has been described, this peak value is set to an arbitrary value less than 1 and less than 0.866 depending on the application. However, it is clear that an effect can be obtained.
Of course, the present invention is not limited to the inverter control but is effective also in the converter control, as is apparent from the AF example.
[0028]
【The invention's effect】
As described above in detail, according to the present invention, desired control can be performed with a modulation rate lower than that in the prior art, so that distortion-free control is possible even for wider changes in DC voltage and AC voltage. Since the modulation rate is smaller than 1, it eliminates distortion based on overmodulation and eliminates control instability and waveform distortion based on unstable operation of gate signals and power semiconductor elements generated near the modulation rate 1. be able to.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an example when applied to a UPS according to the present invention.
FIG. 2 is a waveform diagram showing an example of reference sine wave generator output and reference bias waveform generator output of FIG. 1;
FIG. 3 is a circuit diagram showing an example when applied to AF according to the present invention.
FIG. 4 is a circuit diagram showing another example when applied to a UPS according to the present invention.
FIG. 5 is a circuit diagram showing a conventional example when applied to a UPS.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 AC power supply 2 Converter part 21 Converter circuit 22 Storage battery 23 DC smoothing capacitor 3 Inverter part 31 Inverter circuit 4 Filter part 41 Output transformer 42 AC reactor 43 Capacitor 5 Load 6 'Control part 61' Voltage control Unit 611 ′ output voltage setting unit 612 ′ voltage detection circuit 62 ′ waveform generation unit 621 ′ reference sine wave generator 62B ′ bias circuit 622 ′ reference bias waveform generator 623 ′ bias modulation factor calculator 63 ′ current control unit 64 ′ carrier wave Generator 65 'PWM generator 66' Gate amplifier 6 "Controller 61" Voltage controller 62B "Bias circuit 612" Notch filter 7 AC power supply 8 Load 9 Active filter (AF)
91 Converter circuit 92 Capacitor 93 AC reactor 10 Control unit 101 Voltage control unit 1011 Output voltage setting unit 1012 Voltage generation circuit 102 Waveform generation unit 102B Bias circuit 103 Current control unit 1034 Harmonic detector 105 PWM generation unit V * Output voltage Command Io * Output current command Su Reference sine wave waveform Iu * Inverter current command Iu Inverter current Viu * Inverter voltage command TW Carrier wave PWu PWM waveform Vdc DC voltage Sbu Reference bias waveform Kb Bias modulation factor Vbu * Bias waveform Vu * Inverter voltage command Id * DC current command Vr Power supply voltage Sr Reference sine wave waveform Idr * Current command Ihr * Harmonic correction command Su * AC output waveform command Vu Output voltage Icr * AC current command Vir * Voltage command Sbr Reference Bias waveform Kbc Via Modulation rate Vbr * bias waveform Vr * converter - motor voltage command Vdu voltage deviation

Claims (2)

An inverter unit for converting a DC voltage into a three-phase AC voltage, a voltage control unit for performing an operation for controlling the AC voltage and the AC current, a voltage / current control unit including the current control unit, and the voltage / current control unit And an inverter control for controlling an AC voltage and an AC current by providing the PWM generator with the output of the PWM generator. Biasing means for obtaining a first bias waveform by limiting the head of a three-phase sine wave synchronized with the three-phase AC voltage and adding / subtracting the amount reduced by the limit operation to another two-phase sine wave in the apparatus motor controller - the provided, inverter, characterized in that the sum of the bias waveform and the voltage-current control unit output as applied to PWM generator. Instead of the first bias waveform, the head of the three-phase sine wave synchronized with the three-phase AC voltage is limited, and the amount reduced by the limit operation is added to or subtracted from the other two-phase sine wave. 2. The inverter control device according to claim 1, wherein the second bias waveform is multiplied by an AC voltage, a DC voltage, or a coefficient corresponding to both the AC voltage and the DC voltage.

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