JP2770088B2 - Voltage source inverter control apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse width modulation of an inverter, and more particularly to a control device and a method of a voltage type inverter for controlling an output voltage.

[0002]

2. Description of the Related Art A pulse width modulation inverter (hereinafter, referred to as a PWM inverter) alternately controls conduction of positive and negative switching elements constituting an inverter, and averages an output voltage to control a sine wave. The method is adopted. However, when this control method is executed, the switching element has a switching delay due to the turn-off time. Therefore, a short-circuit prevention period is provided so that the positive and negative switching elements do not conduct simultaneously.
As a result, there is a problem that the output voltage of the inverter decreases and waveform distortion occurs. Conventionally, Japanese Patent Laid-Open No. 62-13
As described in Japanese Patent No. 5289, an output voltage drop due to the on-delay of the inverter is calculated based on the output current command signal, and the calculated value is added to the output voltage command of the inverter, and the output accompanying the on-delay is calculated. A method for compensating for the voltage drop has been proposed.

[0003]

In the above prior art, since a constant value is added to the operation value added to the output voltage command of the inverter, the magnitude of the output voltage drop due to on-delay depends on the magnitude of the inverter output current. There is a problem that this cannot be compensated for even if it changes. The purpose of the present invention is
An object of the present invention is to easily and accurately determine the magnitude of an output voltage drop due to on-delay, and to add the magnitude to an output voltage command to make the inverter output voltage a sine wave without waveform distortion.

[0004]

The object of the present invention is to provide a voltage drop compensator.
Compensation signal generation means, and the voltage drop compensation signal generation means
Are the excitation current signal, torque current signal and primary angular frequency
AC signal for generating AC current signal of each phase from command signal
Signal generation means, and a voltage that is a continuous function of the alternating current signal.
The drop compensation curve is reduced according to the magnitude of the AC current signal.
Compensation area separating means for separating into at least three or more compensation areas
And the following voltage drop compensation amount for each compensation area
Compensation voltage means generated by equation and inverter output current
Current phase angle calculation means for calculating the phase angle of each phase of
The polarity of the voltage drop compensation amount is determined from the output of the current phase calculation means.
This can be achieved by comprising a polarity determining means . Note that Yn = An · X + Bn (region αn−1 ≦ X <αn, number of regions m ≧ 3) where Yn: voltage drop compensation amount An: on-delay compensation coefficient Bn of region αn −1 ≦ X <αn : region αn− 1 ≦ X <αn on-delay initial value X: AC current command without polarity , where | A1 |> | A2 |>...> | An |> 0 αn>αn−1>...>Α1> α0 = 0 and voltage drop Compensation signal generation means is provided and this voltage drop
The compensation signal generating means includes an exciting current signal and a torque current signal.
Current signal generating means for obtaining the magnitude of the current signal from
The on-delay compensation angle is obtained from the output of the current signal generation means.
Compensation angle generating means, and a continuous function of the AC current signal.
A certain voltage drop compensation curve is reduced according to the compensation angle.
A compensating region separating means for separating into three or more compensating regions,
The voltage drop compensation amount that differs for each compensation area is calculated by the following equation.
Compensation voltage means generated from each of the inverter output current
Current phase angle calculating means for calculating a phase angle of a phase;
Determine the polarity of the voltage drop compensation amount from the output of the phase calculation means
This is achieved by comprising the polarity determining means . Serial Yn = An / θin · X + Bn ( region αn-1 ≦ X <αn, the number of areas m ≧ 3) where, Yn: the voltage drop compensation amount .theta.in: Onderei compensation angle .alpha.n points in the area αn-1 ≦ X <αn An: On-delay compensation coefficient Bn in the region αn−1 ≦ X <αn Bn: On-delay initial value X in the region αn −1 ≦ X <αn : current phase angle where | A1 |> | A2 |>. αn>αn−1>...>α1> α0 = 0

[0005]

According to the present invention , the output associated with the on-delay of the inverter is provided.
Separate the voltage drop compensation region into at least three regions
This allows the output voltage drop to be calculated accurately and easily.
And separate the compensation region into a number of regions.
The more the amount of change in the compensation voltage decreases,
It is possible to obtain a small high-accuracy AC voltage command signal.
You. As a result, the output voltage of the inverter becomes positive with less distortion.
It becomes a sine wave, greatly suppressing the waveform distortion of the output current of the inverter.
Control to prevent torque ripple from occurring in the AC motor.
And high performance can be achieved .

[0006]

An embodiment of the present invention will be described below with reference to FIG. The PWM inverter 1 includes three sets of transistors as positive and negative switching elements, receives a pulse width modulation signal from a PWM pulse calculator 9, converts a DC voltage into a three-phase AC voltage, and converts the converted three-phase AC voltage. An AC voltage is supplied to the AC motor 2. The speed of the AC motor 2 is determined by a speed detector 3
And the speed signal Wr, which is the detection output of the speed detector 3, is supplied to the subtractor 4 and the adder 11. Subtractor 4
Are supplied with a speed command signal Wr * and a speed signal Wr, and a signal corresponding to the deviation of each signal is supplied to the speed controller 5. The speed controller 5 outputs a torque current command signal Iq * for making the output signal of the subtractor 4 zero. The torque current command signal Iq * is supplied to a voltage command calculator 6, a slip angular frequency calculator 1
0, supplied to the compensation voltage calculator 13, the slip frequency calculator 10 calculates the slip angle frequency signal Ws * from the excitation current command signal Id * and the torque current command signal Iq *, and sends this calculation signal to the adder 11. Output. The adder 11 adds the slip angular frequency signal Ws * and the speed signal Wr to generate a primary angular frequency command signal W1 *, and outputs this signal to the voltage command calculator 6 and the integrator 12. The integrator 12 time-integrates the signal W1 * to generate a coordinate reference signal W1t, and outputs this signal to the compensation voltage calculator 13 and the coordinate converter 7. The voltage command calculator 6 outputs the exciting current command signal Id * and the torque current command signal Id *.
Based on q * and primary angular frequency command signal W1 *, voltage command signals Vd * and Vq * of the rotating coordinate system of AC motor 2 are calculated.
Each voltage command signal is obtained by the following equations (1) and (2). Vd * = r1 · Id * −W1 * · (l1 + l2) · Iq * (1) Vq * = r1 · Iq * + W1 * · l1 · Id * + W1 * · M · Id * / (1 + T2S) • (2) r1: primary resistance value l1: primary leakage inductance value l2: secondary leakage inductance value M: excitation inductance value T2: secondary time constant S: differential operator The coordinate converter 7 outputs the voltage command signal Vd. *, Vq * and the coordinate reference signal W1t, and according to the coordinate reference signal W1t, the voltage command signals Vd *, Vq * are converted into three-phase AC voltage command signals Vu *, Vv *, Vw * of the stator coordinate system of the AC motor 2. Convert to This AC voltage command signal is added to the compensation voltage signals Vfu *, Vfv *, Vfw * from the compensation voltage calculator 13 in the adder 8 and converted into output voltage command signals Vu **, Vv **, Vw **. Is done. This output voltage command signal is supplied to the PWM pulse calculator 9 and is compared with a carrier signal to be converted into a pulse width modulation signal. When the pulse width modulation signal is generated, the pulse width modulation signal is generated by adding an on-delay for preventing the transistors on the positive and negative sides of the PWM inverter 1 from conducting simultaneously. The switching of each transistor of the PWM inverter 1 is controlled by the pulse width modulation signal, and the DC voltage is converted into a three-phase AC voltage.
The three-phase AC voltage command signals Vu *, Vv *, Vw * are shown in FIG.
(3).

The compensation voltage calculator 13 is configured to calculate compensation voltage signals Vfu *, Vfv *, Vfw * from the excitation current command signal Id *, the torque current command signal Iq *, and the coordinate reference signal W1t. FIG. 2 shows a typical configuration. The AC current command calculator 14 generates AC current command signals Iu *, Iv *, Iw * based on the excitation current command signal Id *, the torque current command signal Iq *, and the coordinate reference signal W1t. Each AC current command signal is obtained by equations (4), (5), and (6) in FIG. The arc tangent calculator 20 calculates the current phase angle from the excitation current command signal Id * and the torque current command signal Iq * according to the following equation (7), and outputs the calculation result to the adder 21. θ = ARCTAN (Iq * / Id *) (7) The adder 21 adds the current phase angle θ and the coordinate reference signal W1t to generate a U-phase current phase angle θiu *, This signal is supplied to the polarity determining calculator 18A. The subtractor 23 calculates the output of the constant generator 22 from the U-phase current phase angle θiu * by 2π /
3 is subtracted to generate a V-phase current phase angle θiv *, and this signal is supplied to the polarity determination calculator 18B. The subtractor 25
4π / 3, which is the output of the constant generator 24, is subtracted from the U-phase current phase angle θiu * to generate a W-phase current phase angle θiw *, and this signal is supplied to the polarity determination calculator 18C.

Since the operating principle is the same for the U, V and W phases, only the U phase will be described. Absolute value calculator 15A
Is supplied with an AC current command signal Iu *, and the AC current command signal | Iu * | without polarity, which has been subjected to absolute value processing, is supplied to a compensation region separation calculator 16A and a function generator 17A. Compensation area separation computing unit 16A outputs a non-polarity AC current command signal | I
u * | to determine the compensation region separation information, and the function generator 17A
To supply the compensation region separation information. The function generator 17A
It consists of a plurality of function units, selects one function unit corresponding to the compensation region separation information, and determines the magnitude of the on-delay compensation voltage from the non-polarity AC current command | Iu * |
Vfu * | is supplied to the polarity determining calculator 18A.

For example, as shown in FIG. 3, when the voltage drop compensation curve P has an S-shaped characteristic, the alternating current command signal is expressed by the following equation (8) when the area A (0 to ia) is obtained. ib)
Equation (9) in the case of, and Equation (1) in the case of the area c (ib ~)
0), the compensation region is separated, and a function unit corresponding to the compensation region is selected. Note that i1 and i2 indicate alternating current command signals having different magnitudes. Y = A1 · X + B1 (area B) (8) Y = A2 · X + B2 (area B) (9) Y = A3 · X + B3 (area C) (10) Y: On-delay compensation voltage A1, A2, A3: On-delay compensation coefficients for areas A, B, and B B1, B2, B3: On-delay initial values for areas A, B, and C X: AC current command without polarity | Iu * | The polarity determination calculator 18A calculates the on-delay compensation voltage Vfu * from the U-phase current phase angle θiu * and the magnitude of the on-delay compensation voltage | Vfu * | according to the following equation (11). Vfu * = | Vfu * | (θiu *: 0 ° to 180 °) Vfu * = − | Vfu * | (θiu *: 180 ° to 360 °) (11) Obtain the on-delay compensation coefficient and the initial value In this case, in FIG. 1, under the condition that the primary angular frequency command signal W1 * = 0 and the voltage command signal Vq * = 0, the relationship between the output current Iu and the voltage drop Vfu is calculated by operating the PWM inverter 1. Measure and determine the on-delay compensation coefficient and initial value. As described above, there are three areas depending on the magnitude of the AC current command.
For the case of dividing into
However, if the voltage drop compensation curve is a continuous function of the AC current,
Then, if the area is divided into three or more,
Can be expressed as follows: sand
That is, Yn = An · X + Bn (region αn−1 ≦ X <αn, number of regions m ≧ 3) where αn−1 ≦ X <αn (n ≧ 1) represents the region of X.
Then, X is divided into three or more (m ≧ 3 ) regions. Where | A1 |> | A2 |>...> | An |> 0 αn>αn−1>...>Α1> α0 = 0

In this manner, the on-delay compensation voltage corresponding to the magnitude of the AC current command signal is accurately obtained.
Therefore, when an AC current signal that matches the actual current is generated, an on-delay compensation voltage corresponding to the magnitude is calculated, and a compensation voltage signal Vfu * shown in FIG. Is output. In FIG. 4, (A) shows an AC current command signal i1, i2, (B) shows an on-delay compensation voltage | Vfu * |
(C) shows the on-delay compensation voltage | Vfu * | for the AC current command signal i2.

When the compensation voltage signal Vfu * is added to the AC voltage command signal Vu *, the output voltage command signal Vu ** is output as a signal as shown in FIG. In FIG. 5, Vu * is an AC voltage command signal, i is an AC current command signal,
Vfu is the AC current command signal i as described in FIG.
Vu ** indicates an output voltage command signal obtained by compensating the AC voltage command signal Vu * with the ON delay compensation voltage signal Vfu. As described above, in this embodiment, since the accurate on-delay compensation voltage corresponding to the magnitude of the AC current command is added to the three-phase AC voltage command,
The occurrence of waveform distortion in the output current of inverter 1 can be suppressed, and the occurrence of torque ripple in AC motor 2 can be prevented.

Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, the on-delay compensation voltage is calculated directly from the magnitude and phase angle of the output current instead of obtaining the AC current command signal. Compensation voltage calculator 13
Other than the above, the description is omitted because it is the same as FIG. The method of generating the current phase angles θiu *, θiv *, θiw * of each phase is the same as that of FIG. The operating principle is U phase, V phase,
Since the same applies to the W phase, only the U phase will be described. The current calculator 30 calculates the magnitude I1 * of the output current from the excitation current command signal Id * and the torque current command signal Iq * according to the equation (12) in FIG. 32. The on-delay compensation angle calculators 31 and 32 determine that the output current I1 * is I1 * SIN (W1t).
The current values Ia and Ib in FIG. 3 are taken as angles, and the on-delay compensation angles θia and θib are obtained from the following equations (13) and (14), and the function generator 34A and the compensation area Output to the separation arithmetic unit 33A. θia = ARCSIN (Ia / I1) = (Ia / I1) + (Ia / I1) 3/6 + ··· ≒ (Ia / I1) ····· (13) θib = ARCSIN (Ib / I1) = ( Ib / I1) + (Ib / I1) 3/6 + ··· ≒ (Ib / I1) ····· (14) U -phase current phase angle Shitaiu *, the compensation region separation calculator 33
A, a function generator 34A and a polarity determination calculator 35A. The compensation area separation calculator 33A determines the compensation area separation information from the U-phase current phase angle θiu * and the outputs of the on-delay compensation angle calculators 31 and 32, and supplies the compensation area separation information to the function generator 34A. . The function generator 34A is composed of a plurality of function units, selects one corresponding function unit from the compensation area separation information, and selects the U-phase current phase angle θiu.
* And the output θi of the on-delay compensation angle calculators 31 and 32
The magnitude | Vfu * | of the on-delay compensation voltage is calculated from a and θib and supplied to the polarity determination calculator 18A.

For example, as shown in FIG.
When u * is in the range of 0 to 90 ° and the on-delay compensation angle is in the range A (0 to θia), the formula (15) is used.
In the case of θib), the compensation region is separated so as to satisfy Expression (16), and in the case of region c (θibｉ), Expression (17), and the corresponding function unit is selected. Y = A1 / θia · X + B1 (area B) (15) Y = A2 / θib · X + B2 (area B) (16) Y = A3 · X + B3 (area C) (17) Y : On-delay compensation voltage | Vfu * | A1, A2, A3: On-delay compensation coefficients of areas A, B, and C B1, B2, B3: On-delay initial values of areas A, B, and C X: Current phase angle θiu * Polarity determination calculation The unit 35A calculates the on-delay compensation voltage Vfu * from the U-phase current phase angle θiu * and the magnitude of the on-delay compensation voltage | Vfu * | according to the following equation (18). Vfu * = | Vfu * | (θiu *: 0 ° to 180 °) Vfu * = − | Vfu * | (θiu *: 180 ° to 360 °) (18) The above depends on the magnitude of the on-delay compensation angle. Three areas
For the case of dividing into
However, if the voltage drop compensation curve is a continuous function of the AC current,
Then, if the area is divided into three or more,
Can be expressed as follows: sand
That is , Yn = An / θin · X + Bn (region αn−1 ≦ X <α
n, the number of areas m ≧ 3) where αn−1 ≦ X <αn (n ≧
1) represents an area of X, and X is an area of three or more (m ≧ 3)
Divided into Θin is in the region αn−1 ≦ X <αn.
Represents the on-delay compensation angle at the point αn. However, | A1 |> | A2 |>...> | An |> 0 αn>αn−1>...>Α1> α0 = 0 Thus, in this embodiment, the magnitude and phase angle of the output current are Since the corresponding accurate on-delay compensation voltage is added to the three-phase AC voltage command, it is possible to suppress the occurrence of waveform distortion in the output current of inverter 1 and to prevent the occurrence of torque ripple in AC motor 2. be able to.

As described above, in the above embodiment, the switching element is a transistor. However, a GTO element or an IGB
It can also be applied to a voltage type inverter using a T element. Further, the polarity determination arithmetic units 18A and 35A determine the polarity based on the current phase angle θi *, but the same result can be obtained by the determination using the following equation (19). Vfu * = | Vfu * | (Iu * ≧ 0, Iu ≧ 0) Vfu * = − | Vfu * | (Iu * <0, Iu <0) (19) Furthermore, the function generators 17A and 34A Although it is composed of three functional units, it can be composed of a plurality of (two or more) functional units. Similarly, although the on-delay compensation angle calculator is composed of two pieces, it can be composed of a plurality of (two or more) calculators. As a special case, when the output current value does not change or the change is small, the output current I1 * in FIG. 6 may be fixed, and the current calculator 30 may be used as a constant generator. Lastly, the inputs of the voltage compensation calculator are the torque current command signal and the excitation current command signal, but they can also be configured by feedback amounts.

[0015]

As described above, according to the present invention,
Compensation area for output voltage drop due to inverter on-delay
Is divided into at least three regions,
The amount of pressure drop can be calculated accurately and easily.
In addition, as the compensation area is divided into many areas,
In order to reduce the amount of change in the
It becomes possible to obtain a flowing voltage command signal. This allows
The output voltage of the inverter is a sine wave with little distortion,
The AC motor can greatly suppress the waveform distortion of the output current of the inverter.
To prevent the occurrence of torque ripple
And high performance can be achieved .

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 is an on-delay compensation voltage calculator

FIG. 3 shows an output example of an on-delay compensation voltage calculator.

FIG. 4 is an output example of an on-delay compensation voltage calculator

FIG. 5 is an output example of an on-delay compensation voltage calculator.

FIG. 6 illustrates an on-delay compensation voltage calculator according to another embodiment of the present invention.

FIG. 7 shows an output example of an on-delay compensation voltage calculator.

FIG. 8 shows equations (3), (4), (5), and (6).
Expression, Expression (12)

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inverter 2 AC motor 3 Speed detector 4 Subtractor 5 Speed controller 6 Voltage command calculator 7 Coordinate converter 8 Adder 9 Pulse calculator 10 Slip frequency calculator 11 Adder 12 Integrator 13 Compensation voltage calculator

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-135389 (JP, A) JP-A-62-135289 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02P 5/408-5/412 H02P 7/628-7/632 H02P 21/00 H02M 7/48

Claims (4)

(57) [Claims] An AC output voltage command is calculated based on a voltage command signal of each phase of the AC motor calculated from an excitation current command signal, a torque current command signal, and a primary angular frequency command signal of the AC motor, and In a control device for a voltage-type inverter that performs pulse width modulation control by a voltage command, a voltage drop compensation signal generating means is provided, and the voltage drop compensation signal generating means includes an exciting current signal, a torque current signal, and a primary angular frequency command signal. An AC current signal generating means for generating an AC current signal of each phase from the following, and a continuous function of the AC current signal.
Voltage drop compensation curve according to the magnitude of the AC current signal
Compensation region separation for separating into at least three or more compensation regions
Means and the amount of voltage drop compensation different for each compensation area are as follows:
Compensation voltage means generated by an arithmetic expression, current phase angle calculation means for calculating the phase angle of each phase of the inverter output current,
A polarity determining means for determining the polarity of the voltage drop compensation amount from the output of the current phase calculating means. Note that Yn = An · X + Bn (region αn−1 ≦ X <αn, number of regions m ≧ 3) where Yn: voltage drop compensation amount An: on-delay compensation coefficient Bn of region αn −1 ≦ X <αn : region αn− 1 ≦ X <αn on-delay initial value X: AC current command without polarity , where | A1 |> | A2 |>... || An |> 0 αn>αn−1>...>Α1> α0 = 0 2. An AC output voltage command is calculated based on a voltage command signal of each phase of the AC motor calculated from an excitation current command signal, a torque current command signal and a primary angular frequency command signal of the AC motor, and In a control device for a voltage-type inverter that performs pulse width modulation control by a voltage command, a voltage drop compensation signal generating means is provided, and the voltage drop compensation signal generating means generates a magnitude of a current signal from an exciting current signal and a torque current signal. Current signal generating means for obtaining an on-delay compensation angle from the output of the current signal generating means, and a voltage drop which is a continuous function of the AC current signal.
At least three or more compensation curves are set according to the compensation angle.
Compensation region separating means for separating into a compensation region, and the compensation region
Generates a different amount of voltage drop compensation for each of the following formulas
Compensation voltage means, current phase angle calculation means for calculating the phase angle of each phase of the inverter output current, and polarity determination means for determining the polarity of the voltage drop compensation amount from the output of the current phase calculation means. Characteristic voltage-type inverter control device. Serial Yn = An / θin · X + Bn ( region αn-1 ≦ X <αn, the number of areas m ≧ 3) where, Yn: the voltage drop compensation amount .theta.in: Onderei compensation angle .alpha.n points in the area αn-1 ≦ X <αn An: On-delay compensation coefficient Bn in region αn-1 ≦ X <αn Bn: On-delay initial value X in region αn -1 ≦ X <αn : Current phase angle where | A1 |> | A2 |>. αn>αn−1>...>α1> α0 = 0 3. An AC output voltage command is calculated based on a voltage command signal of each phase of the AC motor calculated from an excitation current command signal, a torque current command signal, and a primary angular frequency command signal of the AC motor, and the AC output voltage command is calculated. a method for controlling a voltage source inverter for controlling the pulse width modulation by the voltage command, excitation current signal, and generates an alternating current signal of each phase and a torque current signal and the primary angular frequency command signal, the alternating current signal
The voltage drop compensation curve, which is a continuous function of
Divided into at least three or more compensation areas according to the size of the signal
And the following voltage drop compensation amount for each compensation area
Generated by formula to calculate the phase angle of each phase of the inverter output current to determine the polarity of the voltage drop compensation amount from the current phase angle control of a voltage source inverter and generates a voltage drop compensation signal Method. Note that Yn = An · X + Bn (region αn−1 ≦ X <αn, number of regions m ≧ 3) where Yn: voltage drop compensation amount An: on-delay compensation coefficient Bn of region αn −1 ≦ X <αn : region αn− On-delay initial value X of 1 ≦ X <αn : AC current command without polarity , where | A1 |> | A2 |>...> | An |> 0 αn>αn−1>...>Α1> α0 = 0 4. An AC output voltage command is calculated based on a voltage command signal of each phase of the AC motor calculated from an excitation current command signal, a torque current command signal, and a primary angular frequency command signal of the AC motor. a method for controlling a voltage source inverter for controlling the pulse width modulation by the voltage command, and generates a current signal to obtain the magnitude of the current signal from the excitation current signal and the torque current signal, obtains the on-delay compensating angle than said current signal, the Voltage that is a continuous function of the alternating current signal
At least three or more drop compensation curves are required according to the compensation angle.
Separated into upper compensation regions, and a different voltage drop for each compensation region.
The lower compensation amount is generated by the following equation, the phase angle of each phase of the inverter output current is calculated, the polarity of the voltage drop compensation amount is determined from the current phase angle, and a voltage drop compensation signal is generated. Voltage type inverter control method. Serial Yn = An / θin · X + Bn ( region αn-1 ≦ X <αn, the number of areas m ≧ 3) where, Yn: the voltage drop compensation amount .theta.in: Onderei compensation angle .alpha.n points in the area αn-1 ≦ X <αn An: On-delay compensation coefficient Bn in region αn-1 ≦ X <αn Bn: On-delay initial value X in region αn -1 ≦ X <αn : Current phase angle where | A1 |> | A2 |>. αn>αn−1>...>α1> α0 = 0