JP2012178944A - Power conversion device, power conversion system, and motor inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion device which facilities dynamic setting of a target value of a DC output voltage so that a mechanism or operation for executing detection and estimation of the DC output voltage are not required, a current waveform to be input is not distorted and efficiency of power conversion is sufficiently enhanced.SOLUTION: The power conversion device includes: a conversion circuit which has a switching element for performing switching in accordance with a drive pulse signal, and performs AC-DC conversion to an AC voltage to be input; an operation signal generation part which generates an operation signal for determining the operational amount of the switching element; a pulse signal generation part which performs pulse width modulation modulating the operation signal into a signal wave, and generates the drive pulse signal in accordance with the operation signal. The operation signal generation part detects the modulation degree in the pulse width modulation and generates the operation signal based a detection value of the modulation degree.

Description

  The present invention relates to a power conversion device that converts alternating voltage into direct current, and a power conversion system and a motor inverter having the same.

  Conventionally, power converters that convert AC voltage to DC have been widely used. As a kind of power conversion device, a high power factor converter having a configuration in which a PWM bridge type conversion circuit is connected to an AC power supply via a reactor is known.

  The power conversion circuit of this device is configured by, for example, connecting switching elements such as IGBTs (Insulated Gate Bipolar Transistors) by bridge connection and connecting diodes in antiparallel to each switching element. This type of power conversion circuit not only simply converts AC voltage to DC, but also normally has a function to approximate the waveform of the input AC current to a sine wave, a function to bring the power factor close to 1, and a DC output voltage. It has a function of controlling to a target value (desired value).

  As a method for controlling the DC output voltage to the target value, for example, there is a method for detecting the DC output voltage and feedback-controlling each switching element so that the detection result approaches the target value. Japanese Patent Application Laid-Open No. H10-228561 discloses a method for estimating a DC output voltage based on an input AC voltage or AC current instead of detecting a DC output voltage.

JP-A-7-59354

  According to the power converter that controls the DC output voltage to the target value, it is possible to obtain a DC output voltage having a value as close to the desired value as possible. However, if the main purpose of the power converter is to approximate the waveform of the input AC current to a sine wave or to bring the power factor close to 1, etc., how should the target value of the DC output voltage be set? The problem is whether to set it.

  By the way, for example, in the high power factor converter having the configuration described above, the main circuit itself is a boost type. Therefore, in order to make the input AC current into a complete sine wave, the DC output voltage needs to be controlled at least to a value equal to or higher than the peak value of the input AC voltage.

  However, if the target value of the DC output voltage is set too low, the DC output voltage tends to be lower than the peak value of the AC voltage due to fluctuations in the input AC voltage. As a result, the waveform near the peak value of the input alternating current is distorted and the harmonic current increases. On the other hand, if the target value of the DC output voltage is set too high, the switching loss in each switching element increases, leading to a reduction in power conversion efficiency.

  Therefore, as a method for setting the target value of the DC output voltage so as not to distort the input current waveform, (1) the peak value of the input AC voltage is detected, and a certain margin is added to this peak value. The method of setting the value to the target value, and (2) The efficiency of power conversion is somewhat sacrificed, but a value that is considered to be sufficiently higher than the fluctuation of the input AC voltage is fixed as the target value For example, a method of setting the target automatically.

  However, with this method, the target value of the DC output voltage is dynamically set so that the input current waveform is not distorted and the efficiency of power conversion is sufficiently high in the entire operating region having a certain width. It is difficult to set. Further, when a method involving detection and estimation of a DC output voltage is employed, a mechanism and operation for executing detection and estimation of the DC output voltage are required, resulting in an increase in cost of the power converter.

  In view of the above-described problems, the present invention does not require a mechanism or operation for detecting or estimating a DC output voltage, does not distort an input current waveform, and sufficiently increases the efficiency of power conversion. Another object of the present invention is to provide a power converter that makes it easy to dynamically set a target value of a DC output voltage.

  In order to achieve the above object, a power converter according to the present invention includes a switching element that performs switching in accordance with a drive pulse signal, and a converter circuit that performs AC-DC conversion on an input AC voltage by the switching. An operation signal generation unit that generates an operation signal that determines an operation amount of the switching element; and a pulse signal generation that performs pulse width modulation using the operation signal as a signal wave and generates the drive pulse signal according to the operation signal And the operation signal generation unit detects a modulation degree in the pulse width modulation and generates the operation signal based on a detected value of the modulation degree.

  According to this configuration, a mechanism or operation for performing detection and estimation of the DC output voltage is not required, the input current waveform is not distorted, and the power conversion efficiency is sufficiently high. It becomes easy to dynamically set the target value of the output voltage.

  More specifically, the conversion circuit includes a bridge type conversion circuit formed by bridge-connecting a plurality of the switching elements, and the operation signal generation unit receives input AC current as power. The operation signal may be generated so as to approach a sine wave with a rate of 1.

  More specifically, the operation signal generation unit feeds back the detected value of the modulation degree so that the modulation degree approaches a preset target value, or the modulation degree is set in advance. The operation signal may be generated so as to be within a set allowable range.

  More specifically, the operation signal generation unit may generate the operation signal such that the degree of modulation approaches one. More specifically, the conversion circuit may be configured to perform voltage DC-AC conversion in a direction opposite to the direction in which AC-DC conversion is performed.

  In addition, a power conversion system according to the present invention includes the power conversion device having the above-described configuration and a DC-DC conversion circuit that performs bidirectional DC-DC conversion step-up or step-down, and is input to the power conversion device side. An AC voltage obtained by sequentially performing the AC-DC conversion and the DC-DC conversion on the AC voltage is output from the DC-DC conversion circuit side, and input to the DC-DC conversion circuit. The operation of outputting, from the power converter side, an AC voltage obtained by sequentially performing the DC-DC conversion and the DC-AC conversion on the DC voltage.

  In the above configuration, a power distribution system may be connected to the power conversion device side, and a secondary battery may be connected to the DC-DC conversion circuit side. According to this configuration, the power conversion system can be used as a power conditioner for a secondary battery.

  A motor inverter according to the present invention includes a power conversion device according to the above configuration, a DC-AC conversion circuit that receives a DC voltage obtained by the AC-DC conversion, and performs DC-AC conversion on the DC voltage; The AC voltage obtained by the DC-AC conversion is output as a voltage for driving the motor.

  As described above, according to the power conversion device of the present invention, no mechanism or operation for detecting or estimating the DC output voltage is required, the input current waveform is not distorted, and power conversion is performed. It becomes easy to dynamically set the target value of the DC output voltage so that the efficiency is sufficiently high. Moreover, according to the power conversion system and motor inverter which concern on this invention, it becomes possible to enjoy the advantage of the said power converter device.

It is a lineblock diagram of the power converter concerning a 1st embodiment of the present invention. It is a block diagram of the control part which concerns on 1st Embodiment of this invention. It is a typical graph of a pulse signal etc. in the case of insufficient modulation. It is a typical graph of a pulse signal etc. in the case of overmodulation. It is a block diagram of the power converter device which concerns on 2nd Embodiment of this invention. It is a block diagram of the control part which concerns on 2nd Embodiment of this invention. It is a block diagram of the bidirectional | two-way power conditioner which concerns on 3rd Embodiment of this invention. It is a block diagram of the bidirectional | two-way power conditioner which concerns on 4th Embodiment of this invention. It is a block diagram of the motor inverter which concerns on 5th Embodiment of this invention.

  Embodiments of the present invention will be described below by taking each of the first to fifth embodiments as an example.

1. 1st Embodiment [About the structure of a power converter, etc.]
First, as a first embodiment, a power conversion device (high power factor converter) corresponding to a single-phase AC power supply will be described. FIG. 1 is a configuration diagram of the power conversion device 9. As shown in the figure, the power conversion device 9 includes a main circuit 1 and a control unit 2.

  The main circuit 1 includes a bridge type conversion circuit 11, a current / voltage detection circuit 12, a reactor L1, a capacitor C1, an output terminal T1, and the like. The main circuit 1 is connected to a single-phase AC power supply E1, and receives an AC input current Ii and an AC input voltage Vs from the single-phase AC power supply E1.

  The bridge type conversion circuit 11 has switching elements (Q1 to Q4) connected in a full bridge, forming a PWM bridge type conversion circuit. In each embodiment of the present invention, the switching element is an NPN type IGBT, but other types such as a power MOSFET may be adopted.

  As the connection form of each switching element (Q1 to Q4), the collector of the switching element Q2 is connected to the emitter of the switching element Q1, the collector of the switching element Q4 is connected to the emitter of the switching element Q3, and the collector of the switching element Q1 is connected. The collector of the switching element Q3 is connected, and the emitter of the switching element Q4 is connected to the emitter of the switching element Q2.

  The connection point between the switching element Q3 and the switching element Q4 is connected to the positive side of the single-phase AC power supply E1 via the inductor L1, and the connection point between the switching element Q1 and the switching element Q2 is the single-phase AC power supply. Connected to the negative electrode side of E1. Further, the upper output end of the bridge type conversion circuit 11 (the connection point between the switching element Q1 and the switching element Q3) is connected to one end of the capacitor C1 and the upper output terminal T1, and the lower side of the bridge type conversion circuit 11 is connected to the lower side. The output end (the connection point between the switching element Q2 and the switching element Q4) is connected to the other end of the capacitor C1 and the lower output terminal T1.

  In addition, a diode is connected in antiparallel to each of the switching elements (Q1 to Q4). In addition, each switching element (Q1 to Q4) receives a drive pulse signal (G1 to G4) corresponding to itself from the control unit 2, and is turned on / off according to the input drive pulse signal. Switching.

  The current voltage detection circuit 12 detects the waveforms of the AC input current Ii and the AC input voltage Vs. The current-voltage detection circuit 12 is a signal (referred to as “input current signal”) representing the waveform of the detected AC input current Ii and a signal (referred to as “input voltage signal”) representing the waveform of the detected AC input voltage Vs. ) Is output to the control unit 2.

  The control unit 2 generates drive pulse signals (G1 to G4) based on the input current signal and the input voltage signal input from the main circuit 1 side, and outputs them to the switching elements (Q1 to Q4).

[Detailed configuration of control unit]
Next, a detailed configuration of the control unit 2 will be described. FIG. 2 is a configuration diagram of the control unit 2. As shown in the figure, the control unit 2 includes a reference sine wave generation unit 21, a multiplier 22, a subtractor 23, a PI controller 24, a compensation signal generation unit 25, an adder 26, a triangular wave generation unit 27, and a PWM comparator 28. , A modulation degree control unit 29, a gate drive circuit 30, and the like.

  The reference sine wave generation unit 21 performs a zero-cross detection process (detection process of timing when the voltage value becomes zero) and the like for the input voltage signal input from the main circuit 1 side, and is a reference in phase with the AC input voltage Vs Generate and output a sine wave.

The multiplier 22 performs a process of multiplying the reference sine wave output from the reference sine wave generation unit 21 by a modulation degree correction value C _MV (details will be described later). A waveform signal obtained by the multiplication is output to the subtractor 23.

  The subtracter 23 performs processing for subtracting the waveform of the AC input current Ii from the waveform of the signal output from the multiplier 22 based on the input current signal input from the main circuit 1 side. A signal having a waveform obtained by the subtraction is output to the PI controller 24.

  The PI controller 24 calculates an output value so that the value of the signal output from the subtracter 23 approaches zero, and outputs a signal representing this output value to the adder 26. That is, the PI controller 24 executes PI control so that the deviation between the waveform of the signal output from the multiplier 22 and the waveform of the AC input current Ii is small. As a result, the AC input current Ii is controlled to approach a sine wave with a power factor of 1.

  The compensation signal generator 25 generates a compensation signal for compensating for the back electromotive voltage generated in the main circuit 1. Based on the input current signal input from the main circuit 1 side, the compensation signal generation unit 25 generates a signal having a value obtained by multiplying the AC input voltage Vs by a predetermined coefficient K as a compensation signal, and outputs the signal to the adder 26.

  The adder 26 performs processing for adding the value of the compensation signal to the value of the output signal of the PI controller 24. Thereby, feedforward (FF) control for compensating the back electromotive voltage is realized. The waveform signal obtained by the addition is output to the non-inverting input terminal of the PWM comparator 28 and the modulation degree control unit 29 as the operation signal mv that determines the operation amount of the bridge type conversion circuit 11.

  The triangular wave generation unit 27 generates a reference triangular wave TRI signal having a predetermined period and amplitude, and outputs the signal to the inverting input terminal of the PWM comparator 28. The PWM comparator 28 compares the values of the signals input to the input terminals, and generates a signal (a pulse signal in which H level and L level appear alternately) according to the comparison result.

  That is, the PWM comparator 28 performs pulse width modulation (PWM) of a carrier modulation method using the operation signal mv as a signal wave and the reference triangular wave TRI as a carrier wave. The modulation degree MV in the pulse width modulation is represented by a ratio between the amplitude of the operation signal mv (signal wave) and the amplitude of the reference triangular wave TRI (carrier wave). The pulse signal generated by the PWM comparator 28 is output to the gate drive circuit 30.

  The modulation degree control unit 29 performs feedback control for bringing the modulation degree MV closer to the target value. The modulation degree detection unit 29a, the target modulation degree signal generation unit 29b, the subtractor 29c, and the PI controller 29d are provided. I have.

  The modulation degree detection unit 29a detects the amplitude of the input operation signal, and is a ratio between the detection result (the amplitude of the operation signal) and the amplitude of the reference triangular wave TRI (a predetermined value) at the present time. Modulation degree MV is detected. In addition, when the amplitude of the reference triangular wave TRI is set to 1, the amplitude of the detected operation signal can be regarded as the modulation degree. The detected signal indicating the current modulation degree MV is output to the subtractor 29c.

  The target modulation degree signal generation unit 29b generates a signal representing the target value of the modulation degree MV and outputs it to the subtractor 29c. Note that it is ideal that the degree of modulation MV is 1 for the reason described later, and therefore it is usually preferable to set this target value to 1. However, the target value is not limited to 1. For example, the target value may be slightly smaller than 1 in order to prevent the modulation degree MV from exceeding 1 more reliably. The target value may be fixed at all times or may be updated by a predetermined means.

  The subtractor 29c performs processing for subtracting the current modulation degree MV from the target modulation degree based on the signals input from the modulation degree detection unit 29a and the target modulation degree signal generation unit 29b. A signal having a value obtained by the subtraction is output to the PI controller 29d.

The PI controller 29d calculates the modulation degree correction value C _MV described above so that the value of the signal output from the subtractor 29c approaches zero, and outputs a signal representing the modulation degree correction value C _MV to the multiplier 22. To do. That is, the PI controller 29d performs PI control so that the deviation between the target modulation degree and the current modulation degree MV is small.

As described above, the modulation degree correction value _CMV is multiplied by the reference sine wave output from the reference sine wave generation unit 21. As a result, the modulation degree MV is feedback-controlled so as to approach the target value.

  The gate drive circuit 30 generates drive pulse signals (G1 to G4) according to the pulse signal input from the PWM comparator 28, and outputs it to the switching elements (Q1 to Q4). Thereby, PWM control of each switching element (Q1-Q4) is implement | achieved.

[Operation and modulation degree of power conversion circuit]
The power conversion circuit 9 is configured as described above, and by switching each switching element (Q1 to Q4) in the bridge type conversion circuit 11, the AC input voltage Vs input from the single-phase AC power supply E1 is converted to DC. The voltage is converted into a voltage and output from the output terminal T1 as a DC output voltage Vo.

  Further, as described above, the control unit 2 controls the switching elements (Q1 to Q4) so that the AC input current Ii approaches a sine wave having a power factor of 1 and the modulation degree MV approaches 1 of the target value. An operation signal mv that determines an operation amount is generated. Then, the control unit 2 performs pulse width modulation of a carrier modulation method using the operation signal mv as a signal wave and the reference triangular wave TRI as a carrier wave, and generates drive pulse signals (G1 to G4) corresponding to the operation signal mv. Then, each switching element (Q1 to Q4) is driven.

  Here, for the pulse width conversion performed by the control unit 2, a schematic graph of a pulse signal or the like when the modulation degree MV is smaller than 1 (insufficient modulation) is shown in FIG. 3, and when the modulation degree MV is larger than 1 (overmodulation). 4 is a schematic graph of the pulse signal and the like generated in FIG. The modulation degree MV (= the amplitude of the operation signal mv / the amplitude of the reference triangular wave TRI) is 0.7 (= 0.7 / 1.0) in FIG. 3, and 1.2 ( = 1.2 / 1.0).

  As shown in FIG. 3, in the case of undermodulation, the DC output voltage Vo tends to be excessive, and the switching loss of each switching element (Q1 to Q4) increases, which may lead to a reduction in power conversion efficiency. On the other hand, as shown in FIG. 4, in the case of overmodulation, the DC output voltage Vo tends to be insufficient, and when the DC output voltage Vo becomes lower than the peak value of the AC input voltage Vs, the waveform near the peak value of the AC input current Ii. Is distorted and the harmonic current is likely to increase.

  For this reason, it can be said that the degree of modulation MV is desirably maintained as close to 1 as possible. According to the power conversion device 9, even when the AC input voltage Vs or the DC output current fluctuates, the modulation degree MV is dynamically controlled so that it always becomes a value close to 1. As a result, the DC output voltage Vo is dynamically controlled so as to have an optimum value.

  The power converter 9 controls the modulation degree MV as described above, but the output voltage is not directly controlled. Therefore, when a power supply system to the load is formed using the power conversion device 9, a device for voltage adjustment (DC output) is provided between the power conversion device 9 and the load (that is, the rear stage side of the main circuit 1). A device that adjusts the voltage Vo so as to match the load may be provided. Thereby, while being able to supply an appropriate input voltage to the load, a power supply system utilizing the features of the power conversion device 9 is realized.

2. Second Embodiment Next, as a second embodiment, a power conversion device (high power factor converter) corresponding to a three-phase AC power supply will be described. FIG. 5 is a configuration diagram of the power conversion device 9a. As shown in the figure, the power conversion device 9 a includes a main circuit 3 and a control unit 4.

  The main circuit 3 includes a bridge type conversion circuit 31, a current / voltage detection circuit 32, a reactor (L1 to L3), a capacitor C1, and an output terminal T1. The main circuit 3 is connected to a three-phase AC power source E2, and from the three-phase AC power source E2, three-phase (U phase, V phase, and W phase) AC input currents (Iu, Iv, Iw) and an AC input voltage (Vu, Vv, Vw) is input. The subscripts u, v, and w represent the U phase, the V phase, and the W phase, respectively.

  The bridge type conversion circuit 31 has switching elements (Q1 to Q6) connected in a full bridge, and forms a PWM bridge type conversion circuit.

  As the connection form of each switching element (Q1 to Q6), the collector of the switching element Q2 is connected to the emitter of the switching element Q1, the collector of the switching element Q4 is connected to the emitter of the switching element Q3, and the emitter of the switching element Q5 is connected. The collector of the switching element Q6 is connected. The collectors of switching elements Q1, Q3, and Q5 are connected to each other, and the emitters of switching elements Q2, Q4, and Q6 are connected to each other.

  The connection point between the switching element Q1 and the switching element Q2 is connected to the U-phase power supply line of the three-phase AC power supply E2 via the inductor L1, and the connection point between the switching element Q3 and the switching element Q4 is connected to the inductor L2. Is connected to the V-phase power supply line of the three-phase AC power supply E2, and the connection point between the switching element Q5 and the switching element Q6 is connected to the W-phase power supply line of the three-phase AC power supply E2 via the inductor L3. The The upper output terminal of the bridge type conversion circuit 31 (the connection point of the switching elements Q1, Q3, and Q5) is connected to one end of the capacitor C1 and the upper output terminal T1. The output end (the connection point of the switching elements Q2, Q4, and Q6) is connected to the other end of the capacitor C1 and the lower output terminal T1.

  In addition, a diode is connected in antiparallel to each of the switching elements (Q1 to Q6). In addition, each switching element (Q1 to Q6) receives a driving pulse signal (G1 to G6) corresponding to itself from the control unit 4, and performs switching between conduction / non-conduction according to the driving pulse signal. Do.

  The current voltage detection circuit 32 detects the waveforms of the AC input currents (Iu, Iv, Iw) and AC input voltages (Vu, Vv, Vw) of each phase. The current voltage detection circuit 12 outputs the detected waveform of the AC input current of each phase and the detected waveform of each AC input voltage to the control unit 4.

  The control unit 4 generates drive pulse signals (G1 to G6) based on the input current signal and the input voltage signal input from the main circuit 2 side, and outputs them to the switching elements (Q1 to Q6).

[Detailed configuration of control unit]
Next, a detailed configuration of the control unit 4 will be described. FIG. 6 is a configuration diagram of the control unit 4. As shown in the figure, the control unit 4 includes a coordinate conversion unit 41 corresponding to the current value, a subtracter (42a, 42b), a PI controller (43a, 43b), a coordinate conversion unit 44 corresponding to the voltage value, and a compensation. A processing unit (45a, 45b), an adder (46a, 46b), an inverse coordinate conversion unit 47, a triangular wave generation unit 28, a PWM pulse generation unit 49, a modulation degree control unit 50, a gate drive circuit 51, and the like are provided.

  The coordinate conversion unit 41 performs coordinate conversion (including three-phase two-phase conversion and rotational coordinate conversion) on the waveform of the AC input current of each phase input from the main circuit 3 side, and d-axis component (effective) of the AC input current Current component) signal Id and q-axis component (reactive current component) signal Iq. The signal Id is output to the adder 42a, and the signal Iq is output to the adder 42b.

The subtractor 42a performs a process of subtracting the value of the signal Id from the modulation degree correction value C _MV (described later in detail). A signal having a value obtained by the subtraction is output to the PI subtractor 43a. The subtractor 42b performs a process of subtracting the value of the signal Iq from the zero current value (0A). A signal having a value obtained by the subtraction is output to the PI subtractor 43b.

The PI controller 43a calculates an output value so that the value of the signal output from the subtractor 42a approaches zero, and outputs a signal representing this output value to the adder 46a. That is, the PI controller 43a performs PI control so that the deviation between the modulation degree correction value _CMV and the value of the signal Id becomes small. In this way, the amplitude of the effective current component is controlled.

  The PI controller 43b calculates an output value so that the value of the signal output from the subtractor 42b approaches zero, and outputs a signal representing this output value to the adder 46b. That is, the PI controller 43b executes PI control so that the value of the signal Iq approaches zero. In this way, the amplitude of the reactive current component is adjusted to approach zero so that the power factor 1 is maintained, and the AC input current is controlled to approach a sine wave having a power factor of 1.

  The coordinate conversion unit 44 performs coordinate conversion on the waveform of the AC input voltage of each phase input from the main circuit 3 side, and generates a d-axis component signal Vd and a q-axis component signal Vq of the AC input voltage. The signal Vd is output to the compensation processing unit 45a, and the signal Vq is output to the compensation processing unit 45b.

  The compensation signal generator (45a, 45b) generates a compensation signal for compensating the back electromotive voltage generated in the main circuit 3. More specifically, the compensation processing unit 45a generates a signal having a value obtained by multiplying the value of the signal Vd by a predetermined coefficient K1 as a compensation signal, and outputs the compensation signal to the adder 46a. The compensation signal generation unit 45b generates a signal having a value obtained by multiplying the value of the signal Vq by a predetermined coefficient K2 as a compensation signal, and outputs the signal to the adder 46b.

  The adder 46a performs a process of adding the value of the compensation signal output from the compensation processing unit 45a to the output value of the PI controller 43a. A signal having a value obtained by the addition is output to the inverse coordinate conversion unit 47 and the modulation degree control unit 50 as a signal (converter amplitude md) corresponding to the amplitude of the adjusted effective current component.

  The adder 46b performs a process of adding the value of the compensation signal output from the compensation processing unit 45b to the output value of the PI controller 43b. A signal having a value obtained by the addition is output to the inverse coordinate conversion unit 47 as a signal corresponding to the amplitude of the reactive current component after adjustment. By these addition processes, feedforward (FF) control for compensating the back electromotive voltage is realized.

  The inverse coordinate conversion unit 47 performs inverse coordinate conversion (inverse of the coordinate conversion performed by the coordinate conversion unit 41) on the input signal (d-axis value) from the adder 46a and the input signal (q-axis value) from the adder 46b. Process). By the inverse coordinate transformation, an operation signal mu corresponding to the U phase, an operation signal mv corresponding to the V phase, and an operation signal mw corresponding to the W phase are generated as operation signals for determining the operation amount of the bridge type conversion circuit 11. The These operation signals are output to the PWM pulse generator 49.

  The triangular wave generator 48 generates a reference triangular wave TRI signal having a predetermined period and amplitude, and outputs the signal to the PWM pulse generator 49. The PWM pulse generator 49 compares the values of the operation signal and the reference triangular wave TRI for each of the U phase, the V phase, and the W phase, and a signal (H level and L level alternately) according to the comparison result. Appearing pulse signal).

  That is, the PWM pulse generation unit 49 performs pulse width modulation (PWM) of the carrier modulation method using the operation signal of each phase as a signal wave and the reference triangular wave TRI as a carrier wave. The modulation degree MD in the pulse width modulation is represented by the ratio between the amplitude of the operation signal (signal wave) and the amplitude of the reference triangular wave TRI (carrier wave). Each pulse signal generated by the PWM pulse generator 49 is output to the gate drive circuit 51.

  The modulation degree control unit 50 performs feedback control for bringing the modulation degree MD closer to the target value. The modulation degree detection unit 50a, the target modulation degree signal generation unit 50b, the subtractor 50c, and the PI controller 50d are provided. I have.

  The modulation degree detection unit 29a performs scale conversion by dividing the value of the signal input from the adder 46a by the amplitude (predetermined value) of the reference triangular wave TRI. Since the value of the signal input from the adder 46a represents the amplitude of the operation signal, the current modulation degree MD is detected by the scale conversion. When the amplitude of the reference triangular wave TRI is set to 1, the value of the signal input from the adder 46a can be regarded as the modulation degree. The detected signal representing the current modulation degree MD is output to the subtractor 50c.

  The target modulation degree signal generation unit 50b generates a signal representing the target value of the modulation degree MD and outputs the signal to the subtracter 50c. As in the case of the first embodiment, it is ideal that the modulation degree MD is 1. Therefore, it is usually preferable to set this target value to 1. However, the target value is not limited to 1. For example, the target value may be slightly smaller than 1 in order to prevent the modulation degree MV from exceeding 1 more reliably. The target value may be fixed at all times or may be updated by a predetermined means.

  The subtractor 50c performs a process of subtracting the current modulation degree MD from the target modulation degree based on signals input from the modulation degree detection unit 50a and the target modulation degree signal generation unit 50b. A signal having a value obtained by the subtraction is output to the PI controller 50d.

PI controller 50d calculates the aforementioned modulation index correction value C _MV so that the value of the signal outputted from the subtracter 50c approaches zero, outputs a signal representing the modulation factor compensation value C _MV to the subtractor 42a To do. That is, the PI controller 50d performs PI control so that the deviation between the target modulation degree and the current modulation degree MD is small.

As previously described, the signal values the value is subtracted signal Id from the modulation degree correction value C _MV is output to PI subtractor 43a. As a result, the modulation degree MD is feedback-controlled so as to approach the target value.

  The gate drive circuit 30 generates drive pulse signals (G1 to G4) according to the pulse signal input from the PWM comparator 28, and outputs it to the switching elements (Q1 to Q4). Thereby, PWM control of each switching element (Q1-Q4) is implement | achieved.

[Operation of power conversion circuit]
The power conversion circuit 9a is configured as described above, and by switching each switching element (Q1 to Q6) in the bridge type conversion circuit 31, the AC input voltage input from the three-phase AC power supply E2 is converted into a DC voltage. And output from the output terminal T1 as a DC output voltage Vo.

  Further, as described above, the control unit 4 operates the switching elements (Q1 to Q6) so that the AC input current approaches a sine wave having a power factor of 1 and the modulation degree MD approaches 1 of the target value. An operation signal (mu, mv, mw) that determines the quantity is generated. Then, the control unit 4 performs pulse width modulation of a carrier modulation method using each operation signal (mu, mv, mw) as a signal wave and the reference triangular wave TRI as a carrier wave, and a driving pulse corresponding to these operation signals. A signal (G1-G6) is produced | generated and each switching element (Q1-Q6) is driven.

  According to the power conversion device 9a, as in the case of the power conversion device 9 according to the first embodiment, even if the AC input voltage or the DC output current fluctuates, the modulation degree MD is always set to a value near 1. Is dynamically controlled. As a result, the DC output voltage Vo is dynamically controlled so as to have an optimum value.

  The power conversion device 9a controls the modulation degree MD as described above, but the output voltage is not directly controlled. Therefore, when a power supply system to the load is formed using the power conversion device 9a, a voltage adjustment device (DC output) is provided between the power conversion device 9a and the load (that is, the rear stage side of the main circuit 3). A device that adjusts the voltage Vo so as to match the load may be provided. Thereby, while being able to supply an appropriate input voltage to the load, a power supply system utilizing the features of the power converter 9a is realized.

3. 3rd Embodiment As above-mentioned, the power converter device 9 (high power factor converter) corresponding to a single phase alternating current power supply was demonstrated as 1st Embodiment. About the structure form of the power converter device 9, it is possible to utilize for the apparatus of various uses. As an apparatus using such a configuration, a bi-directional power conditioner [power conditioner] (one form of a power conversion system) for a secondary battery will be described as an example, and will be described below as a third embodiment.

  FIG. 7 is a configuration diagram of the bidirectional power conditioner 10. As shown in the figure, the bidirectional power conditioner 10 includes a main circuit 1 a and a control unit 2.

  The main circuit 1a includes a bridge type conversion circuit 11, a current / voltage detection circuit 12, a reactor (L1, L2, L4), a capacitor (C1, C2), a bidirectional chopper circuit 5, and the like. Note that the configurations of the bridge type conversion circuit 11 and the current-voltage detection circuit 12 are the same as those of the first embodiment, and thus description thereof is omitted. In addition to the functions equivalent to those of the first embodiment, the control unit 2 outputs the drive pulse signals (G1 to G4) so that the DC / AC conversion of the voltage is performed in the direction opposite to the direction in which the AC / DC conversion is performed. It also has a function to output.

  The main circuit 1a is connected to a power distribution system E3 that supplies single-phase AC power and a secondary battery BAT, so that bidirectional power transmission (charging and discharging of the secondary battery BAT) is possible. AC power (AC input current Ii and AC input voltage Vs) is input to the main circuit 1a from the distribution system E3, and DC power is input from the secondary battery BAT.

  The bidirectional chopper circuit 5 includes switching elements (Q7, Q8), a reactor L4, and a capacitor C3. The emitter of switching element Q7 is connected to the collector of switching element Q8 and one end of reactor L4. The collector of the switching element Q7 is connected to the upper output end of the bridge type conversion circuit 11 and one end of the capacitor C1. The emitter of the switching element Q8 is connected to the lower output end of the bridge type conversion circuit 11, the other end of the capacitor C1, and the negative electrode side of the secondary battery BAT. The other end of the reactor L4 is connected to the positive electrode side of the secondary battery BAT. Both ends of the capacitor C3 are connected to the positive electrode side and the negative electrode side of the secondary battery BAT, respectively.

  The bidirectional chopper circuit 5 receives a pulse signal from a control device (not shown), and the switching elements (Q7, Q8) perform switching in response thereto. The bidirectional chopper circuit 5 is either in the direction from the bridge type conversion circuit 11 side to the secondary battery BAT side or in the direction from the secondary battery BAT side to the bridge type conversion circuit 11 side (that is, bidirectional). It has a function of converting DC voltage (DC-DC conversion). The voltage conversion by the bidirectional chopper circuit 5 may be either step-up or step-down.

  The connection point between the switching element Q3 and the switching element Q4 is connected to the positive side of the power distribution system E3 via the inductor L1, and the connection point between the switching element Q1 and the switching element Q2 is connected to the negative side of the power distribution system E3. It is connected. Both ends of the capacitor C2 are connected to the positive electrode side and the negative electrode side of the power distribution system E3, respectively.

  When the bi-directional power conditioner 10 charges the secondary battery BAT, the AC-DC conversion by the bridge type conversion circuit 11 and the bi-directional chopper circuit 5 with respect to the AC voltage (AC input voltage Vs) input from the power distribution system E3. The switching elements (Q1 to Q4, O7, Q8) are controlled so that the direct current to direct current conversion is sequentially performed. Then, the bidirectional power conditioner 10 outputs the DC voltage obtained by these conversion operations to the secondary battery BAT.

  Further, when the bidirectional power converter 10 discharges the secondary battery BAT, the DC voltage input from the secondary battery BAT is converted into DC / DC conversion by the bidirectional chopper circuit 5 and DC / AC by the bridge type conversion circuit 11. Each switching element (Q1-Q4, O7, Q8) is controlled so that conversion is performed in order. And the bidirectional | two-way power conditioner 10 outputs the alternating voltage obtained by these conversion operation | movement to the power distribution system E3.

  In the present embodiment, the main circuit 1a has a two-stage configuration of the bridge type conversion circuit 11 and the bidirectional chopper circuit 5. However, the control procedure of the bridge type conversion circuit 11 at the time of charging the secondary battery BAT is as follows. This is the same as in the first embodiment. Therefore, also in the bidirectional power converter 10 of the present embodiment, the modulation degree MV of the pulse width modulation performed by the control unit 2 is dynamically changed so as to always be a value near 1 based on the same principle as in the first embodiment. Be controlled.

  Note that the bidirectional power converter 10 of the present embodiment is a power conversion device having a configuration substantially equivalent to that of the first embodiment (however, the voltage DC-AC conversion is performed in a direction opposite to the direction in which AC-DC conversion is performed. And a bidirectional chopper circuit 5, a power distribution system E 3 is connected to the power converter, and a secondary battery BAT is connected to the bidirectional chopper circuit 5. It can be seen as something like that.

  If it sees in this way, the bidirectional | two-way power conditioner 10 carries out the direct-current voltage obtained by performing alternating current-direct current conversion and direct current-direct current conversion to the alternating current voltage input into the power converter device side of the bidirectional chopper circuit 5. An AC voltage obtained by sequentially performing DC-DC conversion and DC-AC conversion on the DC voltage input to the bidirectional chopper circuit 5 side is output from the power converter side. It can be said that it performs operation.

4). 4th Embodiment As above-mentioned, the power converter 9a (high power factor converter) corresponding to a three-phase alternating current power supply was demonstrated as 2nd Embodiment. About the structure form of the power converter device 9a, it can utilize for the apparatus of various uses. As an apparatus using such a configuration form, a bi-directional power conditioner (one form of a power conversion system) for a secondary battery will be described as an example, and will be described below as a fourth embodiment.

  FIG. 8 is a configuration diagram of the bidirectional power conditioner 10a. As shown in the figure, the bidirectional power conditioner 10 a includes a main circuit 2 a and a control unit 4.

  The main circuit 2a includes a bridge type conversion circuit 31, a current / voltage detection circuit 32, a reactor (L1 to L4), a capacitor C1, and a bidirectional chopper circuit 5. The configurations of the bridge type conversion circuit 31 and the current / voltage detection circuit 32 are equivalent to those of the first embodiment, and the configuration of the bidirectional chopper circuit 5 is equivalent to that of the third embodiment. Each description is omitted. In addition to the functions equivalent to those of the second embodiment, the control unit 4 outputs the drive pulse signals (G1 to G6) so that the voltage DC-AC conversion is performed in the direction opposite to the direction in which AC-DC conversion is performed. It also has a function to output.

  The main circuit 2a is connected to a power distribution system E4 that supplies three-phase AC power and a secondary battery BAT, so that bidirectional power transmission (charging and discharging of the secondary battery BAT) is possible. The main circuit 2a receives AC power (AC input currents (Iu, Iv, Iw) and AC input voltages (Vu, Vv, Vw) of each phase) from the distribution system E4, and DC from the secondary battery BAT. Power is input.

  The connection point between the switching element Q1 and the switching element Q2 is connected to the U-phase power supply line of the distribution system E4 via the inductor L1, and the connection point between the switching element Q3 and the switching element Q4 is connected via the inductor L2. The connection point between the switching element Q5 and the switching element Q6 is connected to the W-phase power supply line of the distribution system E4 via the inductor L3.

  When the bidirectional power conditioner 10a charges the secondary battery BAT, the AC voltage input from the power distribution system E4 is subjected to AC-DC conversion by the bridge type conversion circuit 31 and DC-DC conversion by the bidirectional chopper circuit 5. Each switching element (Q1-Q8) is controlled so that it may be performed in order. Then, the bidirectional power conditioner 10a outputs the DC voltage obtained by these conversion operations to the secondary battery BAT.

  Further, when the bidirectional power conditioner 10a discharges the secondary battery BAT, the DC voltage input from the secondary battery BAT is converted into DC / DC conversion by the bidirectional chopper circuit 5 and DC / AC by the bridge type conversion circuit 31. Each switching element (Q1-Q8) is controlled so that conversion is performed in order. And the bidirectional | two-way power conditioner 10a outputs the alternating voltage obtained by these conversion operation | movement to the power distribution system E4.

  In the present embodiment, the main circuit 2a has a two-stage configuration of the bridge type conversion circuit 31 and the bidirectional chopper circuit 5, but the control procedure of the bridge type conversion circuit 31 at the time of charging the secondary battery BAT This is the same as in the second embodiment. Therefore, also in the bidirectional power conditioner 10a of the present embodiment, the modulation degree MD of the pulse width modulation performed by the control unit 4 is dynamically set so as to always be a value near 1 based on the same principle as in the second embodiment. Be controlled.

  Note that the bidirectional power converter 10a of the present embodiment is a power conversion device having a configuration that is substantially the same as that of the second embodiment (however, a voltage DC-AC conversion in a direction opposite to the direction in which AC-DC conversion is performed). And a bidirectional chopper circuit 5, a power distribution system E 4 is connected to the power conversion device side, and a secondary battery BAT is connected to the bidirectional chopper circuit 5 side. It can be seen as something like that.

  If it sees in this way, the bidirectional | two-way power conditioner 10a makes the alternating current voltage input into the power converter side the direct current voltage obtained by performing alternating current-direct current conversion and direct current-direct current conversion in order of the bidirectional chopper circuit 5 An AC voltage obtained by sequentially performing DC-DC conversion and DC-AC conversion on the DC voltage input to the bidirectional chopper circuit 5 side is output from the power converter side. It can be said that it performs operation.

5. 5th Embodiment Next, the motor inverter which applied the power converter device 9 which concerns on 1st Embodiment as components for power factor correction (power factor correction: PFC) is demonstrated. FIG. 9 is a configuration diagram of the motor inverter 6. As shown in the figure, the motor inverter 6 has a power converter 9 and a DC-AC converter circuit 7. The motor inverter 6 is used in a form in which a single-phase AC power source E1 that supplies single-phase AC power is connected to the input side, and a motor 8 that is driven by AC power is connected to the output side.

  The motor inverter 6 converts the AC voltage input from the single-phase AC power source E1 into a DC voltage by the power conversion device 9, and then converts the AC voltage to an AC voltage by the DC-AC conversion device 7, and then outputs it to the motor 8. Then, the motor 8 is driven. Here, since the power converter device 9 has a function as a high power factor converter, it plays a role of improving the power factor.

  As described above, the motor inverter 6 includes the power conversion device 9 and the DC-AC conversion circuit 7 that receives the DC voltage obtained by AC-DC conversion and performs DC-AC conversion on the DC voltage. The AC voltage obtained by this DC-AC conversion is output as a voltage for driving the motor. In addition, it is also possible to apply the power converter device 9a which concerns on 2nd Embodiment instead of the power converter device 9 as components for power factor improvement. In this case, the motor inverter 6 corresponds to a three-phase AC power source.

6). Others As described above, the power conversion device according to the present embodiment includes a switching element that performs switching in accordance with a drive pulse signal, and performs main-to-DC conversion on an input AC voltage by the switching. A circuit, a function unit (operation signal generation unit) that generates an operation signal that determines an operation amount of the switching element, and pulse width modulation using the operation signal as a signal wave, and the drive pulse signal corresponding to the operation signal And a function unit (pulse signal generation unit).

  The operation signal generation unit detects the modulation degree in the pulse width modulation, and generates the operation signal based on the detected value of the modulation degree. Therefore, according to the power conversion device according to each embodiment, a mechanism (such as a DC voltage detector) or operation for detecting or estimating a DC output voltage is not required, and an input current waveform is not distorted. In addition, it is easy to dynamically set the target value of the DC output voltage so that the efficiency of power conversion becomes sufficiently high. In addition, it is possible to perform more appropriate control of the output voltage that does not depend on errors in the detection circuit or variations in the elements of the main circuit, and that can dynamically follow fluctuations in the AC input voltage and load fluctuations in the power converter. Therefore, it is possible to realize a power conversion device that has less harmonic input current than the conventional one, is more efficient, and achieves downsizing and cost reduction.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The present invention can be implemented in various modified forms without departing from the gist thereof.

  For example, in each of the embodiments described above, the operation signal generation unit feeds back a detection value of the modulation degree and generates an operation signal so that the modulation degree approaches a preset target value. . In this regard, other forms may be adopted as a form for reflecting the detected value in the generation of the operation signal, a specific form of feedback of the detected value, and the like without departing from the gist of the present invention. Absent. In addition, instead of making the modulation degree approach the preset target value, a form of generating the operation signal may be adopted so that the modulation degree is within the preset allowable range.

  The present invention can be used in a power conversion device that converts an alternating voltage into a direct voltage.

1, 1a, 3, 3a Main circuit 2, 4 Control unit 5 Bidirectional chopper circuit (DC-DC conversion circuit)
6 Motor inverter 7 DC-AC conversion circuit 8 Motor 9, 9a, Power converter 10, 10a Bi-directional power converter (power conversion system)
DESCRIPTION OF SYMBOLS 11, 31 Bridge type | mold conversion circuit 12, 32 Current voltage detection circuit 21 Reference | standard sine wave generation part 22 Multiplier 23 Subtractor 24 PI controller 25 Compensation signal generation part 26 Adder 27 Triangular wave generation part 28 PWM comparator 29 Modulation degree control part 29a Modulation degree detector 29b Target modulation degree signal generator 29c Subtractor 29d PI controller 30 Gate drive circuit 41 Coordinate converter 42a, 42b Subtractor 43a, 43b PI controller 44 Coordinate converter 45a, 45b Compensation processor 46a, 46b Adder 47 Inverse coordinate conversion unit 48 Triangular wave generation unit 49 PWM pulse generation unit 50 Modulation degree control unit 50a Modulation degree detection unit 50b Target modulation degree signal generation unit 50c Subtractor 50d PI controller 51 Gate drive circuit BAT Secondary battery C1 ~ C3 Capacitor E AC power supply E1 Single-phase AC power supply E2 Three-phase AC power supply E3 Distribution system (single phase)
E4 Distribution system (three-phase)
L1-L4 Reactor Q1-Q8 Switching element T1 Output terminal

Claims (8)

A conversion circuit that performs switching according to the drive pulse signal, and performs AC-DC conversion on the input AC voltage by the switching; and
An operation signal generator for generating an operation signal for determining an operation amount of the switching element;
A pulse signal generation unit that performs pulse width modulation using the operation signal as a signal wave and generates the drive pulse signal according to the operation signal,
The operation signal generator is
A power conversion device that detects a modulation degree in the pulse width modulation and generates the operation signal based on a detected value of the modulation degree. The conversion circuit includes:
A bridge-type conversion circuit formed by bridge-connecting a plurality of the switching elements;
The operation signal generator is
The power conversion device according to claim 1, wherein the operation signal is generated so that an input alternating current approaches a sine wave having a power factor of 1. 5. The operation signal generator is
Feeding back the detected value of the modulation degree;
The operation signal is generated so that the modulation degree approaches a preset target value or the modulation degree falls within a preset allowable range. Power converter. The operation signal generator is
The power conversion device according to claim 3, wherein the operation signal is generated so that the modulation degree approaches 1. The conversion circuit includes:
The power conversion device according to any one of claims 2 to 4, wherein voltage DC-AC conversion is performed in a direction opposite to a direction in which the AC-DC conversion is performed. The power conversion device according to claim 5;
A DC-DC conversion circuit that performs bidirectional DC-DC conversion,
An operation for outputting a DC voltage obtained by sequentially performing the AC-DC conversion and the DC-DC conversion to the AC voltage input to the power conversion device side from the DC-DC conversion circuit side; and
An operation for outputting an AC voltage obtained by sequentially performing the DC-DC conversion and the DC-AC conversion to the DC voltage input to the DC-DC conversion circuit side, from the power converter side;
The power conversion system characterized by performing.   The power conversion system according to claim 6, wherein a power distribution system is connected to the power conversion device side, and a secondary battery is connected to the DC-DC conversion circuit side. The power conversion device according to any one of claims 2 to 4,
A DC voltage obtained by the AC-DC conversion is input, and a DC-AC conversion circuit that performs DC-AC conversion on the DC voltage, and
A motor inverter that outputs an AC voltage obtained by the DC-AC conversion as a voltage for driving a motor.