JP3500380B2 - Power converter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter for controlling opening / closing of an electric valve based on a comparison between a signal wave and a carrier wave to convert DC power into AC power.

[0002]

2. Description of the Related Art FIG. 23 shows, for example, "Electroly
tic Capacitor-less PWM Inv
erter ”(IPEC-Tokyo, 1990, P.
131-138) is a block diagram obtained by rewriting the control circuit of the three-phase inverter shown in FIG.
In the figure, 101 is an oscillator, 102 is a counter, and 10
3 is a ROM in which data of three-phase sine wave is stored, 10
4, 105 and 106 are multiplication type DA converters that multiply a digital value and an analog input value and output the result as an analog value, 107, 108 and 109 are comparators, 110
Is an adder / subtractor, 111 is a PI calculator that performs proportional-plus-integral calculation,
Reference numeral 112 is a triangular wave generator.

Next, the operation will be described. Oscillator 101
The clock output by is divided by the counter 102, and the counter is operated at the basic frequency of the output voltage command value of the three-phase inverter. Using the counter as an address, the three-phase sine wave data from the ROM 103 are respectively multiplied by the DA converter 10
4, 105, 106. Multiplying DA converter 10
The outputs of 4, 105 and 106 are comparators 107 and 107, respectively.
108 and 109, and compares with the triangular wave output from the triangular wave generator 112. This comparison signal Cu, Cv, Cw
Drive an inverter of a three-phase full bridge configuration. In order to match the output voltage amplitude VL of the inverter with the output voltage amplitude command value VL ^* , the adder / subtractor 110 finds an error, the PI calculator 111 amplifies this error, and the multiplication DA converters 104, 105, 106. The analog input value of. Therefore, when the output voltage amplitude VL is lower than the output voltage amplitude command value VL ^* , the multiplication DA converter 104,
The outputs of 105 and 106 increase, and when the output voltage amplitude VL is higher than the output voltage amplitude command value VL ^* , the outputs of the multiplying DA converters 104, 105 and 106 decrease. From this, the amplitude Vt of the triangular wave and the output amplitude V of the multiplication DA converter are
The ratio a to r (= Vr / Vt) changes. FIG. 23 shows
This is an inverter control method generally called triangular wave comparison PWM, and it is known that the output voltage of the inverter in this case is proportional to a. Therefore, the output voltage amplitude VL steadily matches the output voltage amplitude command value VL ^* .

[0004]

Since the control circuit of the conventional three-phase power converter is configured as described above, three multiplying DA converters, which are extremely expensive as compared with operational amplifiers, are used. However, there is a problem that the cost of the control circuit is high.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a power converter capable of realizing the structure of its control circuit at low cost.

[0006]

According to a first aspect of the present invention, there is provided a power converter for controlling the opening / closing of an electric valve based on a comparison between a three-phase sine wave signal and a carrier wave to convert DC power into three-phase AC power. , A sine wave signal generation circuit for generating a sine wave signal for one phase having a constant amplitude, a control output according to a deviation between a command value and an output value of the power conversion device, and 1 from the sine wave signal generation circuit. A multiplication circuit that multiplies a sine wave signal for the phase and outputs the result as a first sine wave signal, and creates a second sine wave signal by advancing the phase of the first sine wave signal from this multiplication circuit by 90 degrees 90 And a two-phase / three-phase conversion circuit that converts the two-phase signal of the first sine wave signal and the second sine wave signal into three phases and outputs the three-phase sine wave signal. It is a thing.

A power converter according to a second aspect of the present invention is a power converter which controls opening / closing of an electric valve based on a comparison between a three-phase sine wave signal and a carrier wave to convert DC power into three-phase AC power, with a constant amplitude. A sine wave signal generating circuit for generating a sine wave signal for one phase, a control output according to a deviation between a command value and an output value of the power conversion device, and a sine wave signal for one phase from the sine wave signal generating circuit. A multiplication circuit that multiplies by and outputs as a first sine wave signal, a 120-degree phase shift circuit that creates a second sine wave signal by delaying the phase of the first sine wave signal from this multiplication circuit by 120 degrees, and Creating the three-phase sine wave signal from the first sine wave signal and the second sine wave signal 3
It is provided with a phase sine wave operation circuit.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Embodiment 1 of the present invention will be described below with reference to the drawings. In FIG.
Reference numeral 1 denotes a three-phase inverter, which is composed of a self-extinguishing type element such as a transistor capable of high-frequency switching or an electric valve such as an IGBT, and is a three-phase full-bridge inverter as shown in FIG. Switching is performed at a high frequency of about 10 to several hundreds times (for example, 60 Hz), and the DC voltage of the DC power supply 2 is converted into a rectangular-wave-shaped high-frequency AC voltage containing a sinusoidal fundamental wave.
3, 4, 5 are reactors, and 6, 7, 8 are capacitors. The reactors 3, 4, 5 and the capacitors 6, 7, 8 constitute a three-phase low-pass filter, which removes harmonics from the rectangular-wave AC voltage generated by the three-phase inverter 1 to generate a sine wave. The output voltage is obtained and power is supplied to the load 9.

A drive circuit 10 switches the arms of the three-phase inverter 1 based on the digital signals Cu, Cv, and Cw output from the voltage control circuit 13. For example, for the U phase, when Cu is 1,
Turn on the transistor Q1 of the U-phase arm, turn off the transistor Q2, turn off the transistor Q1 when Cu is 0,
The transistor Q2 is turned on. Reference numeral 11 denotes a voltage sensor, which determines the instantaneous amplitude or average value amplitude VL of the three-phase output voltage vector and uses it as a feedback signal to the voltage control circuit 13. Reference numeral 12 is a voltage command value generation circuit for outputting the amplitude command value VL ^* of the output voltage.

FIG. 3 is a block diagram showing the structure of the voltage control circuit 13, in which 101 is an oscillator and 102 is a block diagram.
Is a counter, 103 is a ROM in which three-phase sine wave data is stored, 113, 114, 115 are DA converters that convert digital values into analog values and output, 107, 1
08 and 109 are comparators, 110 and 116 are adders / subtractors, 1
11 is a PI calculator for performing proportional-plus-integral calculation, 117 is a constant 1
, 118 is an oscillator, 119 is UP / D
An OWN counter 120 is a multiplication type DA converter that multiplies a digital value and an analog input value and outputs the result as an analog value. 110, 111, 116, 11
7, 118, 119 and 120 form a triangular wave generator as a carrier wave control means.

Next, the operation of the voltage control circuit 13 will be described with reference to FIG. In the conventional example, when controlling the output voltage amplitude,
While the amplitude Vr of the three-phase sine wave signal to be compared with the triangular wave is adjusted by the output of the PI calculator 111, the amplitude Vt of the triangular wave is adjusted in the present embodiment. In the triangular wave comparison PWM, the modulation rate a (= which is the ratio of the amplitude Vt of the triangular wave and the output amplitude Vr of the multiplication type DA converter.
The output voltage is obtained in proportion to Vr / Vt). When the amplitude of the triangular wave is multiplied by (1-X), a = Vr / {Vt (1-X)} (1) is obtained. Equation (1) is approximately a = (Vr / Vt) × (1 + X) (2) when X is small. Therefore, it can be seen that X can be increased or decreased in order to increase or decrease the output voltage.

When the inverter is controlled by comparing the sine wave signal with the triangular wave, the cause that the output voltage cannot be obtained according to the calculated value is the switching delay of the inverter switching element and the voltage drop of the filter reactor. ,
Normally, the output voltage amplitude VL and the output voltage amplitude command value VL ^* can be matched by the modulation factor correction within 10%. Therefore, even when the amplitude of the triangular wave is manipulated by the equation (1), X is within 0.1, and the approximation of the equation (2) is established.

Therefore, as shown in FIG.
The clock output by is divided by the counter 102, and the counter is operated at the basic frequency of the output voltage command value of the three-phase inverter. Three-phase sine wave data is read from the ROM 103 by using the counter as an address, and the DA converters 113 and 1 are provided.
14 and 115. DA converters 113, 114, 1
A three-phase sine wave signal having a constant amplitude is output from 15 and applied to comparators 107, 108 and 109, respectively, and compared with the triangular wave signal output from the multiplication DA converter 120. The comparison signals Cu, Cv, and Cw control an inverter having a three-phase full bridge configuration. In order to match the output voltage amplitude VL of the inverter with the output voltage amplitude command value VL ^* , the adder / subtractor 110 calculates an error, and the PI calculator 111
Then, this error is amplified to obtain the signal X. Adder / subtractor 116
Then, the (1-X) signal is obtained by the constant unit 117 and the multiplication type DA
The converter 120 multiplies the triangular wave by (1-X). Therefore,
The amplitude of the triangular wave applied to the comparator 107, 108 and 109, when the output voltage amplitude VL is the output voltage amplitude command value VL ^* lower is small and the output voltage swing VL is higher than the output voltage amplitude command value VL ^* is greater Therefore, the output voltage amplitude VL constantly matches the output voltage amplitude command value VL ^* . Further, the (1-X) signal for operating the amplitude of the triangular wave can be inexpensively constructed by an operational amplifier or the like.

As described above, in the conventional example, the voltage control by the triangular wave PWM is operated by the three multiplication DA converters for the amplitude of the three-phase sine wave signal, but the present embodiment is inexpensive. Since the circuit creates a (1-X) signal for operating the amplitude of the triangular wave and uses only one multiplication type DA converter for operating the amplitude of the triangular wave by the (1-X) signal, The cost of the control circuit can be reduced.

Embodiment 2. In the first embodiment, 3
Although the amplitude of the triangular wave is manipulated instead of the amplitude of the phase sine wave, in the present embodiment, the amplitude of one phase of the sine wave is manipulated to obtain a three-phase sine wave signal from this sine wave. The configuration will be described.

The second embodiment of the present invention will be described below with reference to FIG. FIG. 4 is a block diagram showing the configuration of the voltage control circuit 13. In the figure, 101 is an oscillator, 1
Reference numeral 02 is a counter, 103 is a ROM that stores data for one phase of a sine wave, 104 is a multiplication DA converter that multiplies a digital value and an analog input value and outputs the result as an analog value, 107 and 108 , 109 is a comparator,
Reference numeral 110 is an adder / subtractor, 111 is a PI calculator for performing proportional-plus-integral calculation, and 112 is a triangular wave generator. 121 is a Δ (delta) modulator, 122 is a low-pass filter, and 123 is a 2-phase / 3-phase conversion circuit that outputs a 3-phase signal from a 2-phase signal.

Next, the operation will be described. . Oscillator 10
The clock output by 1 is divided by the counter 102, and the counter is operated at the basic frequency of the output voltage command value of the three-phase inverter. ROM 103 with counter as address
From the sine wave data to the multiplying DA converter 104.
Inverter output voltage amplitude VL is output voltage amplitude command value VL
^In order to match with ^* , the error is calculated by the adder / subtractor 110,
The PI calculator 111 amplifies this error and uses it as the analog input value of the multiplication DA converter 104. Therefore, when the output voltage amplitude VL is lower than the output voltage amplitude command value VL ^* , the output of the multiplication DA converter 104 increases, and when the output voltage amplitude VL is higher than the output voltage amplitude command value VL ^* , the multiplication type. The output of the DA converter 104 decreases. From the output V1 (first sine wave signal) of the multiplication DA converter 104, the Δ modulator 121 and the low pass filter 122
A second sine wave signal V2 whose phase is advanced by 90 degrees from the sine wave signal V1 is obtained (described later). Then, the two-phase / three-phase conversion circuit 123, based on the first and second sine wave signals V1 and V2,
A three-phase sine wave signal is obtained by performing the following calculation. Vu = V1 (3) Vv = (-1/2) × V1− (√3 / 2) × V2 (4) Vw = (− 1/2) × V1 + (√3 / 2) × V2 (5)

The outputs of the two-phase / three-phase conversion circuit 123 are given to comparators 107, 108 and 109, respectively, and compared with the triangular wave output from the triangular wave generator 112. The comparison signals Cu, Cv, and Cw control an inverter having a three-phase full bridge configuration. V1 is manipulated so that the output voltage amplitude VL and the output voltage amplitude command value VL ^* match, and Vu, Vv, and Vw are created from this V1.
The modulation factor a is controlled in both phases, and the output voltage amplitude VL steadily matches the output voltage amplitude command value VL ^* .

FIG. 5A is a block diagram of the Δ modulator 121, where 201 is a sampler, 202 is an adder / subtractor, and 203.
Is a comparator, 204 is a 1-sample delay device, and 205 is 1bi
A DA converter of t, 206 is an integrator having an integration time constant T. The Δ modulator 121 uses the sampler 2 for every constant sampling.
02 is operated, the error between the input signal and the output signal of the integrator 206 is obtained by the adder / subtractor 202, and the comparator 203 outputs a signal of 1 or 0 according to the sign of the error. The output of the comparator 203 is delayed by one sample time by the one-sample delay unit 204, the signal of 1,0 is converted into the signal of, for example, −1 by the DA converter 205, and this is integrated by the integrator 206. To do.

FIG. 5B shows an example of operation waveforms of the Δ modulator 121. Here, the input signal V1 is the integrator 20
If it is larger than the output of 6, the comparator 203 outputs 1 and
1 is output for one sampling from the DA converter 205,
The output of the integrator 206 increases. On the contrary, if the input signal V1 is smaller than the output of the integrator 206, the comparator 2
03 outputs 0, the DA converter 205 outputs −1 for one sampling, and the output of the integrator 206 decreases. Therefore, as shown in the figure, the output of the integrator 206 with respect to the input signal operates so as to minimize the difference.

If the sampling frequency is sufficiently high with respect to the input signal, the harmonic component contained in the output of the integrator 206 is reduced and becomes substantially equal to the input voltage. In general, Δ
The modulator is used for obtaining a digital signal VD corresponding to the analog input signal V1. However, here, since the output of the integrator 206 becomes equal to the input V1 of the Δ modulator, it is assumed that the input signal VΔ to the integrator 206 leads the input signal V1 of the Δ modulator by 90 degrees. To use. For example, when the frequency of the signal V1 is 60 Hz, the integral time constant T of the integrator 206 is set to 1 / (2π × 60) so that the fundamental wave components of the signals V1 and VΔ have the same amplitude and a phase difference of 90 degrees. Signal. However, VΔ is amplitude 1,
-1 pulse output, so low pass filter 122
To remove the harmonic component. If the sampling frequency is selected to be high (for example, 10 kHz or more), there is almost no effect on the fundamental wave of the low-pass filter 122, and the second sine wave signal V2 advanced by 90 degrees with respect to the first sine wave signal V1. Is obtained.

As described above, in the conventional example, the amplitude of the three-phase sine wave signal was operated by the three multiplying DA converters for the voltage control by the triangular wave PWM. The amplitude of the phase is controlled by one multiplication DA converter, and the delta modulator generates a signal with a 90 degree phase advance, and then the two-phase / three-phase conversion circuit generates a three-phase sine wave signal. Is created and compared with the triangular wave, the cost of the control circuit can be reduced.

Embodiment 3. In the second embodiment, the amplitude of one phase of the sine wave is manipulated to generate a signal with a 90 ° phase advance by the Δ modulator, and then the two-phase / three-phase conversion circuit performs three-phase conversion.
In contrast to the case where the phase sine wave signal is generated, in the present embodiment, a configuration will be described in which a signal whose phase is advanced by 90 degrees is obtained from the LC (R) simulation circuit that instantaneously controls the output voltage.

The third embodiment of the present invention will be described below with reference to FIG. The difference from the second embodiment is that the Δ modulator 121 and the low pass filter 122 are replaced by 90
The phase shift circuit 124 is provided. When the phase shift circuit is composed of a normal analog filter, the response time becomes relatively long with respect to the change of the input signal, but here, LC (R)
A 90 degree phase shift circuit 124 having a short response time is realized by creating a filter model and providing an LC simulation circuit having a feedback configuration for instantaneously controlling the output voltage. As a result, when the amplitude of one phase of the sine wave changes, the amplitude of the three-phase sine wave signal can be changed in an instant.

FIG. 7 shows an explanatory view of the LC (R) filter model. VA is the input voltage to the LC (R) filter, IA is the current of the reactor (L) 301, VC is the voltage of the capacitor (C) 302, IC is the current of the capacitor 302, and IL is the resistance load (R) 303. It is an electric current.

FIG. 8 shows a vector diagram of the circuit of FIG. Assuming that the capacitor voltage VC is 1, if C is set to 1 pu, the phase of the capacitor current IC is advanced by 90 degrees with respect to VC, and its magnitude becomes 1. Therefore, the capacitor voltage V
An LC simulation circuit provided with a feedback control system in the LC (R) filter model is configured to match C with the input VI (V1), and a signal advanced by 90 degrees from VI is obtained.

FIG. 9 shows a block diagram of the 90-degree phase shift circuit 124. 354 is an integrator simulating the reactor 301,
Reference numeral 356 is an integrator simulating the capacitor 302, 357 is a coefficient multiplier simulating the load resistance 303, and 353 and 35.
Reference numeral 5 is an adder / subtractor. The right side of the dotted line simulates the circuit shown in FIG. Here, C is 1 pu and L is 0.1
0.2 pu and R are selected to be about 0.5 to 1 pu so that the damping factor of the LC (R) filter is improved. Here, the error between the input signal VI and the capacitor voltage VC is obtained by the adder / subtractor 351 and this error is amplified by the PI calculator 352 to be the input signal VA to the LC (R) filter.
The PI calculator 352 has a voltage control response of thousands to tens of thousands of rad.
/ Sec. As a result, the capacitor voltage quickly follows the input signal VI, and the capacitor current IC becomes a signal with a 90 ° phase advance from the capacitor voltage. Therefore, the capacitor current IC becomes a signal with a phase advanced by 90 degrees with respect to the input signal (first sine wave signal) V1, and this is output signal (second sine wave signal) V2 of the 90 degree phase shift circuit 124. And After the signal V2 is obtained, a three-phase sine wave signal is created in the same manner as in the second embodiment,
Drive the inverter compared to the triangular wave.

As described above, since the 90-degree phase shift circuit 124 is a circuit that can be easily constructed by an operational amplifier or the like and the response can be made faster, the control circuit can be made lower than in the second embodiment. Can be a cost.

Fourth Embodiment In the third embodiment described above, the case where the 90-degree phase shift circuit 124 is configured by the instantaneous voltage control system of the LC simulation circuit including the PI calculator 352 has been described. However, as shown in FIG. By adding the input signal VI to the 90-degree phase shift circuit 124 to the output of 352 by the adder 358 and using this as the input signal VA to the LC (R) filter model, a command value feedforward configuration is adopted, The response of the voltage control system can be further improved, the responsiveness of the 90-degree phase shift circuit 124 is increased, and the three-phase sine wave signal instantaneously responds to the operation of the amplitude of one phase of the sine wave.

Note that in FIG. 7, FIG. 9, and FIG. 10, R (resistance)
Although it is a simulated circuit including
The phase shifting function itself is not impaired.

Embodiment 5. In the third embodiment, the amplitude of one phase of the sine wave is manipulated, the 90-degree phase circuit 124 generates a signal with a 90-degree phase advance, and then the 2-phase / 3-phase conversion circuit converts the phase into three phases. While creating a sine wave signal,
In the present embodiment, a configuration will be described in which a signal (for V phase) whose phase is delayed by 120 degrees is directly obtained from a circuit that instantaneously controls the output voltage of the LC (R) filter model.

The fifth embodiment of the present invention will be described below with reference to FIG. FIG. 11 is a block diagram showing the configuration of the voltage control circuit 13. In the figure, the point different from the third embodiment is that the first sine wave signal Vu (U phase component) output from the multiplication DA converter 104 is output. Command) to the second sine wave signal (command for V phase) Vv through the 120 degree phase shift circuit 125.
Is obtained, and the following calculation is performed from Vu and Vv by the adder / subtractor 126 as a three-phase sine wave calculation circuit to create the W-phase component command Vw. Vw = -Vu-Vv (6)

The 120-degree phase shift circuit 125 creates an LC (R) filter model similar to that of the above-described third embodiment, and uses an LCR simulation circuit having a feedback structure for instantaneously controlling the output voltage of the model. Short response time 12
A 0 degree phase shift circuit is realized. This LC (R) is shown in FIG.
The vector diagram of a filter model is shown. Capacitor voltage V
If C is 1, C is (√3 / 2) pu and R is 0.5p
If set to u, the reactor current IA is 60 with respect to VC.
The phase advances, and its magnitude becomes 1. Therefore, -IA
Is a signal obtained by delaying the capacitor voltage VC by 120 degrees.
Therefore, the capacitor voltage VC is changed by 120 degrees to the phase shift circuit 125.
The feedback control system is configured so as to match the input signal Vu of, and a signal delayed by 120 degrees from Vu is obtained.

FIG. 13 shows a block diagram of the 120-degree phase shift circuit 125. The difference from the third embodiment is that C is (√
3/2) pu and R are selected to be 0.5 pu, and the reactor current IA multiplied by -1 in the coefficient multiplier 359 is used as the output signal Vv of the 120-degree phase shift circuit 125. As a result, the capacitor voltage quickly follows the input signal Vu, and the reactor current IA becomes a signal with a phase lead of 60 degrees with respect to the capacitor voltage VC. Therefore, the reactor current IA
Is -1 times the input signal (first sine wave signal) Vu
A signal (second sine wave signal) Vv delayed by 120 degrees with respect to the signal Vv, and the signal Vw can be easily obtained by the adder / subtractor 126 from the signals Vu and Vv.

As described above, the 120-degree phase shift circuit 125 is a circuit that can be easily constructed by an operational amplifier or the like, and the response can be made high speed, and in addition, the 2-phase / 3-phase conversion circuit is unnecessary. Therefore, the cost of the control circuit can be further reduced as compared with the third embodiment.

Sixth Embodiment In the fifth embodiment, the case where the 120-degree phase shift circuit 125 is composed of the instantaneous voltage control system of the LC (R) filter model by the PI calculator 352 has been described. However, as shown in FIG. By adding the input signal Vu to the 120-degree phase shift circuit 125 to the output of the device 352 by the adder 358 and using this as the input signal VA to the LC (R) filter model, a command value feedforward configuration is adopted. The response of the voltage control system can be further improved, the responsiveness of the 120-degree phase shift circuit 125 is increased, and a three-phase sine wave signal instantly responds to the operation of the amplitude of one phase of the sine wave.

Embodiment 7. In the third embodiment described above, the case where the 90-degree phase shift circuit 124 is composed of the instantaneous voltage control system of the LC (R) filter model has been described.
In the present embodiment, a configuration will be described in which a signal with a 90 ° phase advance is obtained by an L simulation circuit that is obtained by instantaneously controlling the current of a reactor model.

FIG. 15 shows an explanatory view of the reactor model. VA is a voltage applied to the reactor (L) 401, and IA is a current of the reactor (L) 401. Figure 1
6 shows a vector diagram of the circuit of FIG. If VA is set to 1 and L is set to 1 pu, the reactor current IA becomes VA
The phase is delayed by 90 degrees, and its magnitude is 1. Therefore, a feedback control system is configured so that the reactor current IA coincides with the input VI of the 90-degree phase shift circuit 124, and the applied voltage VA to the reactor that is advanced by 90 degrees from the reactor current IA is obtained.

FIG. 17 shows a 90-degree phase shift circuit (L simulation circuit) 1
24 shows a block diagram of 24. FIG. Reference numeral 453 is an integrator simulating the reactor 401, and the right side of the dotted line simulates the circuit shown in FIG. Here, L is selected to be 1 pu. Further, the error between the input signal VI and the reactor current IA is obtained by the adder / subtractor 451 and this error is calculated by the PI calculator 452.
The voltage is amplified to obtain the applied voltage VA to the reactor. PI
The calculator 452 has a current control response of several thousand to tens of thousands rad / s.
ec is selected. As a result, the reactor current follows the input signal VI at high speed, and the voltage VA applied to the reactor becomes a signal with a phase advanced by 90 degrees from the reactor current. Therefore, the voltage applied to the reactor is the input signal VI
Is a signal with a 90 degree phase advance, and
Degree output signal of phase shift circuit 124 (second sine wave signal) V2
And After V2 is obtained, a three-phase sine wave signal is created in the same manner as in the third embodiment, and compared with the triangular wave to drive the inverter.

As described above, the 90-degree phase shift circuit can be made simpler than that of the third embodiment, and the control circuit can be reduced in cost.

Embodiment 8. In the seventh embodiment described above, the case where the 90-degree phase shift circuit 124 is configured by the instantaneous current control system of the reactor model by the PI calculator 452 is described. However, as shown in FIG. 18, an integrator that amplifies an error is used. 454, a proportional calculator 45 for amplifying the reactor current
5. I by the adder / subtractor 456 for adding / subtracting these signals
It is configured as a P control system, and the output of the adder / subtractor 456 is the applied voltage VA to the reactor model.

Generally, in the PI control system, the control response is provided by the proportional term (P), and the integral term (I) intended to eliminate the steady deviation has a slow response due to stability. On the other hand, in the IP control system shown in FIG. 18, since the control response is designed by the integral term (I), it becomes an integrator with a fast response, and the response of the current control system to the disturbance can be further improved, and it is 90 degrees. The responsiveness of the phase shift circuit is increased, and the sine wave signal of three phases instantly responds to the operation of the amplitude of one phase of the sine wave.

Ninth Embodiment In the fifth embodiment, the case where the 120-degree phase shift circuit 125 is composed of the instantaneous voltage control system of the LC (R) filter model has been described, but in the present embodiment, the current of the reactor model is instantaneously controlled. A configuration for obtaining a signal whose phase is advanced by 120 degrees by the LR simulation circuit configured as above will be described.

FIG. 19 shows an explanatory diagram of the reactor model. VA is a voltage applied to the reactor model, IA is a current of the reactor (L) 401, and 402 is a resistor R connected in series with the reactor. FIG. 20 shows a vector diagram of the circuit shown in FIG. If VA is set to 1, and the series circuit of L and R is set to a power factor of 0.5, the reactor current IA will be VA.
The phase is advanced by 60 degrees, and its magnitude becomes 1. Therefore, -VA is a signal obtained by delaying the reactor current IA by 120 degrees. Therefore, a feedback control system is configured to match the reactor current IA with the input signal (first sine wave signal) Vu of the 120-degree phase shift circuit 125, and a signal delayed by 120 degrees from the reactor current IA (second sine wave). signal)
-Get VA.

FIG. 21 shows a block diagram of the 120-degree phase shift circuit (LR simulation circuit) 125. 453 is reactor 4
01 is an integrator, 458 is a coefficient unit simulating the resistor 402, 457 is an adder / subtractor, and the right side of the dotted line is shown in FIG.
The circuit shown in 9 is simulated. Where the power factor is 0.5
In order to set L to (√3 / 2) pu and R to 0.5 pu
To be selected. In addition, the input signal Vu and the reactor current IA
The error between and is obtained by the adder / subtractor 451 and this error is amplified by the PI calculator 452 to obtain the applied voltage VA to the reactor model. The PI calculator 452 is selected so that the current control response is in the range of thousands to tens of thousands of rad / sec. From this, the reactor current follows the input signal Vu at high speed, and the applied voltage VA to the reactor model is calculated by the coefficient unit 459.
The signal multiplied by 1 becomes a signal whose phase is delayed by 120 degrees from the reactor current. Therefore, -VA becomes a signal whose phase is delayed by 120 degrees with respect to the input signal Vu, and this is used as the output signal (second sine wave signal) Vv of the 120-degree phase shift circuit 125. After Vv is obtained, a three-phase sine wave signal is created in the same manner as in the fifth embodiment, and compared with the triangular wave, the inverter is driven.

As described above, the 120-degree phase shift circuit can be made simpler than that of the fifth embodiment,
The cost of the control circuit can be reduced.

Embodiment 10. In addition, Embodiment 9 described above
In the above, the case in which the 120-degree phase shift circuit 125 is configured by the instantaneous current control system of the reactor model by the PI calculator 452 has been described, but as shown in FIG. 22, the integrator 454 that amplifies the error and the reactor current are amplified. To further improve the response of the current control system by configuring an IP control system with a proportional calculator 455 and an adder / subtractor 456 that adds and subtracts these signals, and using the output of the adder / subtractor 456 as the applied voltage VA to the reactor model. The responsiveness of the 120-degree phase shift circuit is increased, and the sine wave signal of three phases instantly responds to the operation of the amplitude of one phase of the sine wave.

In the first embodiment, the triangular wave is U
P / DOWN counter 119 and multiplication type D / A converter 12
Although it is created by using 0, the same effect can be obtained even if a triangular wave created by an analog circuit is configured to operate by multiplying the (1-X) signal and operating the amplitude of the triangular wave. You can

Further, in the above-mentioned first to tenth embodiments,
Although the carrier of pulse width modulation is configured as a triangular wave,
The carrier wave is not limited to the triangular wave, but may be a sawtooth wave, a sine wave, or the like which is generally used.

In addition, although the first embodiment is applied to a three-phase inverter, it can be applied to a multi-phase inverter having two or more phases with the same idea, and an equivalent effect is obtained. Further, in the above second to tenth embodiments, the case of creating the three-phase sine wave voltage command value has been described, but in the case of the three-phase power converter, the case of creating the sine wave current command value is also described. A similar configuration can be adopted. Further, in each of the above-described embodiments, the invention is configured by combining the circuit elements, but it goes without saying that the same function may be realized by software operating on a computer.

[0051]

The power converter according to the first aspect of the present invention is a power converter that controls opening / closing of an electric valve based on a comparison between a three-phase sine wave signal and a carrier to convert DC power into three-phase AC power. A sine wave signal generating circuit for generating a constant sine wave signal for one phase, a control output according to a deviation between a command value and an output value of the power conversion device, and a sine for one phase from the sine wave signal generating circuit. A multiplication circuit that multiplies with the wave signal and outputs as a first sine wave signal, and creates a second sine wave signal by advancing the phase of the first sine wave signal from this multiplication circuit by 90 degrees 9
A 0-degree phase shift circuit and a two-phase / three-phase conversion circuit for converting a two-phase signal of the first sine wave signal and the second sine wave signal into three phases and outputting the three-phase sine wave signal. Because I prepared
The target of the amplitude control based on the deviation between the command value and the output value is only the sine wave signal for one phase, and the configuration related to this amplitude control is simple and inexpensive.

A power converter according to a second aspect of the present invention is a power converter that controls opening / closing of an electric valve based on a comparison between a three-phase sine wave signal and a carrier wave to convert DC power into three-phase AC power. A sine wave signal generating circuit for generating a sine wave signal for one phase, a control output according to a deviation between a command value and an output value of the power conversion device, and a sine wave signal for one phase from the sine wave signal generating circuit. A multiplication circuit that multiplies by and outputs as a first sine wave signal, a 120-degree phase shift circuit that creates a second sine wave signal by delaying the phase of the first sine wave signal from this multiplication circuit by 120 degrees, and Creating the three-phase sine wave signal from the first sine wave signal and the second sine wave signal 3
Since the phase sine wave calculation circuit is provided, the target of amplitude control based on the deviation between the command value and the output value is only the sine wave signal for one phase, and the configuration related to this amplitude control is simple and inexpensive.

[Brief description of drawings]

FIG. 1 is a block diagram showing a power conversion device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a power converter used in the first embodiment of the present invention.

FIG. 3 is a block diagram showing a voltage control circuit of the power conversion device according to Embodiment 1 of the present invention.

FIG. 4 is a block diagram showing a voltage control circuit of a power conversion device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing the configuration and operation of a Δ modulator used in the second embodiment of the present invention.

FIG. 6 is a block diagram showing a voltage control circuit of a power conversion device according to a third embodiment of the present invention.

FIG. 7 is an LC (R) used in the third embodiment of the present invention.
It is a circuit diagram which shows a filter model.

FIG. 8 LC (R) used in Embodiment 3 of the present invention
It is a vector diagram which shows a filter model.

FIG. 9 is a block diagram showing a 90-degree phase shift circuit used in a third embodiment of the present invention.

FIG. 10 is a block diagram showing a 90-degree phase shift circuit used in a fourth embodiment of the present invention.

FIG. 11 is a block diagram showing a voltage control circuit of a power conversion device according to a fifth embodiment of the present invention.

FIG. 12 LC used in Embodiment 5 of the present invention
It is a vector diagram of an (R) filter model.

FIG. 13 is a block diagram showing a 120-degree phase shift circuit used in the fifth embodiment of the present invention.

FIG. 14 is a block diagram showing a 120-degree phase shift circuit used in Embodiment 6 of the present invention.

FIG. 15 is a circuit diagram showing a reactor model used in a seventh embodiment of the present invention.

FIG. 16 is a vector diagram of a reactor model used in the seventh embodiment of the present invention.

FIG. 17 is a block diagram showing a 90-degree phase shift circuit used in Embodiment 7 of the present invention.

FIG. 18 is a block diagram showing a 90-degree phase shift circuit used in Embodiment 8 of the present invention.

FIG. 19 is a circuit diagram showing a reactor model used in Embodiment 9 of the present invention.

FIG. 20 is a vector diagram of a reactor model used in the ninth embodiment of the present invention.

FIG. 21 is a block diagram showing a 120-degree phase shift circuit used in Embodiment 9 of the present invention.

FIG. 22 shows a device used in Embodiment 10 of the present invention.
It is a block diagram showing a degree phase shift circuit.

FIG. 23 is a block diagram showing a configuration of a conventional power conversion device.

[Explanation of symbols]

1 3 phase inverter, 2 DC power supply, 11 voltage sensor, 12 voltage command value generation circuit, 13 voltage control circuit,
104, 120 multiplying DA converters, 107, 108,
109 comparator, 110, 116 adder / subtractor, 111,
PI arithmetic unit, 112 triangular wave generator, 117 constant unit, 118 oscillator, 121 Δ modulator, 122 low pass filter, 123 two-phase / 3-phase conversion circuit, 124
90 degree phase shift circuit, 125 120 degree phase shift circuit, 206
Integrator, 301 (354), 401 (453) reactor, 302 (356) capacitor, 303 (35
7), 402 (458) resistance, Q1 to Q6 transistors, VL ^* output voltage amplitude command value, VL output voltage amplitude, V1, Vu first sine wave signal, V2, Vv second sine wave signal.

Claims (2)

(57) [Claims] 1. A power converter that controls the opening and closing of an electric valve based on a comparison between a three-phase sine wave signal and a carrier wave to convert DC power into three-phase AC power. A sine wave signal generating circuit for generating, a control output corresponding to a deviation between a command value and an output value of the power conversion device, and a sine wave signal for one phase from the sine wave signal generating circuit are multiplied to obtain a first sine wave. A multiplication circuit for outputting as a wave signal, a 90-degree phase shift circuit for creating a second sine wave signal by advancing the phase of the first sine wave signal from this multiplication circuit by 90 degrees, and the first sine wave signal A power conversion device comprising a two-phase / three-phase conversion circuit that converts a two-phase signal including a second sine wave signal into three phases and outputs the three-phase sine wave signal. 2. A power converter that controls the opening and closing of an electric valve based on a comparison between a three-phase sine wave signal and a carrier wave to convert DC power into three-phase AC power. A sine wave signal generating circuit for generating, a control output corresponding to a deviation between a command value and an output value of the power conversion device, and a sine wave signal for one phase from the sine wave signal generating circuit are multiplied to obtain a first sine wave. A multiplication circuit that outputs as a wave signal, and creates a second sine wave signal in which the phase of the first sine wave signal from this multiplication circuit is delayed by 120 degrees 1
A power conversion device comprising a 20-degree phase shift circuit and a three-phase sine wave operation circuit that creates the three-phase sine wave signal from the first sine wave signal and the second sine wave signal.