WO2017126154A1

WO2017126154A1 - Electric power conversion device and control method therefor

Info

Publication number: WO2017126154A1
Application number: PCT/JP2016/075989
Authority: WO
Inventors: 友一坂下; 義章石黒; 前田　貴史; 福田　秀樹
Original assignee: 三菱電機株式会社; 三菱電機照明株式会社
Priority date: 2016-01-22
Filing date: 2016-09-05
Publication date: 2017-07-27
Also published as: JPWO2017126154A1; JP6309182B2

Abstract

A power supply control unit (2) of the electric power conversion device controls an output voltage (Vo) by performing on/off control of switching components (Q1, Q2) on the basis of an input voltage detection value (Vin), the output voltage detection value (Vo), and a reactor current (IL), and controls the reactor current (IL) such that an input current waveform approaches an input voltage waveform in order to perform power factor improvement control. The power supply control unit performs the power factor improvement control by making an appropriate correction in response to a fluctuation in the input voltage such that the magnitude of a fluctuation in the reactor current (IL) counteracts that of the fluctuation in the input voltage (Vin). Consequently, even in the event of a fluctuation in the input voltage (Vin), a stable step-up/step-down operation can be performed without a fluctuation in the output voltage (Vo).

Description

Power conversion apparatus and control method thereof

The present invention relates to a power conversion device having a power factor improvement function and a control method thereof while performing step-up / step-down conversion from AC power to DC power.

The PFC (Power Factor Correction) circuit used to improve the power factor suppresses harmonics and effectively uses power when stepping up and down converting AC power to DC power. It is widely used as a technique for reducing power consumption and realizing energy saving. Therefore, various types of PFC circuits have been proposed.

For example, in the power conversion device of Patent Document 1, an H-type bridge buck-boost converter is used to individually perform power factor correction control corresponding to boost control, buck control, or buck-boost control. By calculating the current IL *, controlling the reactor peak current value so that the reactor current IL matches the target reactor current IL *, and bringing the input current waveform closer to the input voltage waveform, a high power factor improvement effect is achieved. I try to get it. Further, since a desired output can be obtained with a single-stage converter, high efficiency can be realized at low cost.

Further, in the power factor correction circuit of Patent Document 2, there is no charge / discharge current Ic flowing through a capacitor provided on the input side of the power factor correction circuit, connected to the subsequent stage of the rectifier circuit that rectifies the AC voltage Vin from the AC power supply. Assuming that, in the half cycle of the AC voltage Vin, the circuit current (PFC current Ipfc) is controlled so that the latter half current amount in the half cycle is larger than the first half current amount in the half cycle. Thus, by reducing the influence of the charge / discharge current on the current control of the PFC circuit, a power supply circuit corresponding to a plurality of input levels (or output levels) is realized with one hardware configuration.

WO2014 / 119040 gazette Japanese Patent Laying-Open No. 2015-8583

However, in the power conversion device of Patent Document 1, there is no problem when a stable input voltage is supplied. However, when other devices connected to the same AC power supply are operating, the input voltage Fluctuated and the output voltage and output current changed instantaneously.

In the power factor correction circuit of Patent Document 2, the microcomputer stores the voltage near the peak of the rectified voltage in the current half cycle, and the voltage near the peak of the rectified voltage in the half cycle before the current half cycle The MOSFET is controlled so that the magnitude of the current to the load is maintained when it is determined that there is an instantaneous drop when the difference between the two voltages is greater than a predetermined value. However, there is a problem that when the level that is determined to be an instantaneous drop is not reached, control is not performed, and as a result, the output waveform changes.

The present invention has been made to solve the above-described problems, and is capable of performing a step-up / step-down operation stably so that the output voltage does not fluctuate even when the input voltage fluctuates. It aims at providing the power converter device which has.

In order to solve the above problems, a power converter according to the present invention detects a full-wave rectification circuit that full-wave rectifies an AC voltage of an AC power supply, and an input voltage that has been full-wave rectified by the full-wave rectification circuit. An input voltage detection circuit, a switching element, and a reactor, and a converter that converts the input voltage into a target output voltage, an output voltage detection circuit that detects an output voltage after voltage conversion by the converter, and the reactor A power supply main circuit unit having a current detection circuit for detecting a flowing reactor current; and controlling the output voltage by controlling on / off of the switching element based on the input voltage, the output voltage, and the reactor current, and the reactor A power supply control unit that performs power factor correction control to control the current and bring the input current waveform closer to the input voltage waveform When the input voltage detection circuit detects a fluctuation in which the input voltage decreases from the normal time, the power supply control unit controls the reactor current to be set larger than the normal time so that the input voltage is normal. When a fluctuation rising from the time is detected, the reactor current is set to be smaller than that in the normal state, and control is performed.

The method for controlling the power converter according to the present invention includes a full-wave rectifier circuit that full-wave rectifies an AC voltage of an AC power supply, and an input voltage detection that detects an input voltage after full-wave rectification by the full-wave rectifier circuit. A converter having a circuit, a switching element, and a reactor, which converts the input voltage into a target output voltage, an output voltage detection circuit that detects an output voltage after voltage conversion by the converter, and a reactor current that flows through the reactor A power supply main circuit unit having a current detection circuit for detecting the output voltage, and controlling the output voltage by controlling on / off of the switching element based on the input voltage, the output voltage, and the reactor current, and controlling the reactor current And a power control unit that performs power factor correction control to bring the input current waveform closer to the input voltage waveform. An apparatus control method, wherein the input voltage detection circuit detects the input voltage, an input voltage detection step, the output voltage detection circuit detects the output voltage, and the power control unit. However, in the input voltage detection step, when the fluctuation in which the input voltage decreases from the normal time is detected, the reactor current is set to be larger than that in the normal time, and the fluctuation in which the input voltage increases from the normal time is controlled. A current control step for controlling the reactor current by setting the reactor current to be smaller than normal when detected.

According to the power conversion device and the method for controlling the power conversion device of the present invention, the power supply control unit of the converter that performs the power factor improvement control by controlling the reactor current has the fluctuation of the input voltage when the fluctuation occurs in the input voltage. On the other hand, by performing control so that the reactor current is opposite to the magnitude of the fluctuation, there is an effect that the power factor improvement control can be performed by appropriate correction according to the input voltage fluctuation.

1 is a circuit block diagram illustrating an overall configuration of a power conversion device according to a first embodiment. FIG. 3 is a circuit block diagram illustrating a configuration of a power supply control unit of the power conversion device according to the first embodiment. It is a figure explaining the operation mode of the buck-boost control with respect to the input-output voltage in the power converter device which concerns on Embodiment 1. FIG. It is a figure explaining the peak current control system in the power converter device which concerns on Embodiment 1. FIG. 4 is a flowchart illustrating a calculation control processing procedure of a power supply control unit in the power conversion device according to the first embodiment. It is a wave form diagram at the time of controlling by the peak current in the conventional power converter device. It is a wave form diagram at the time of controlling with the corrected peak current in the power converter device which concerns on Embodiment 1. FIG. 3 is a diagram illustrating a method for generating an ideal value of an input voltage in the power conversion device according to Embodiment 1. FIG. It is a figure explaining the hysteresis comparator control system in the power converter device which concerns on Embodiment 1. FIG. It is a figure explaining the window comparator control system in the power converter device which concerns on Embodiment 1. FIG. It is a circuit block diagram which shows the whole structure of the other embodiment of the power converter device which concerns on Embodiment 1. FIG. FIG. 3 is a circuit block diagram illustrating an overall configuration of a power conversion device according to a second embodiment. FIG. 6 is a circuit block diagram showing a configuration of a power supply control unit of a power conversion device according to a second embodiment.

Hereinafter, the configuration and operation of the power conversion device according to the embodiment of the present invention and details of the control method of the power conversion device will be described with reference to FIGS. 1 to 13.

Embodiment 1 FIG.
FIG. 1 is a circuit block diagram illustrating an overall configuration of the power conversion device according to the first embodiment, and FIG. 2 is a circuit block diagram illustrating a configuration of a power supply control unit of the power conversion device.

First, the configuration of the power conversion device according to the first embodiment will be described with reference to FIGS. 1 and 2. The power conversion apparatus includes a power supply main circuit unit 1 and a power supply control unit 2 that controls the first switching element Q1 and the second switching element Q2 of the converter 5 of the power supply main circuit unit 1.

As shown in FIG. 1, the power supply main circuit unit 1 includes a full-wave rectifier circuit 4 including a diode bridge circuit that full-wave rectifies the AC input voltage Vac supplied from the AC power supply 3, and an input voltage after full-wave rectification | An input capacitor C1 for smoothing noise included in Vac | (hereinafter referred to as a pulsating current voltage) and an amount connected in series for detecting an input voltage detection value Vin of the pulsating voltage | Vac | An input voltage detection circuit 7 comprising voltage resistors R1 and R2, an H-type bridge step-up / down converter 5 (hereinafter referred to as a converter) that adjusts a pulsating voltage | Vac | to a target DC output voltage Vdc, and a converter. Current detecting circuit 6 for detecting the reactor current IL flowing through the reactor L, output capacitor C2 for smoothing the pulsation of the output voltage of the converter 5, and the obtained DC output voltage V An output voltage detection circuit 8 connected in series with voltage dividing resistors R3 and consists R4 for detecting the output voltage detection value Vo of c, in being configured. A load 9 is connected to the output side of the power supply main circuit unit 1.

The converter 5 adjusts the pulsating voltage | Vac | shown in FIG. 3 that has been full-wave rectified by the full-wave rectifier circuit 4 to a target output voltage Vdc. The converter 5 includes a first switching element Q1 and a diode D1. A step-down arm composed of the second switching element Q2 and the diode D2, a connection point between the first switching element Q1 and the diode D1, and the second switching element Q2 and the diode D2. And a reactor L connected between the connection points. Each of the first and second switching elements Q1 and Q2 includes an FET (Field Effect Transistor) element or an IGBT (Insulated Gate Bipolar Transistor) element, which is used for on / off control generated by the power control unit 2. It is driven by a switch signal.

The first switching element Q1 and the diode D1 are connected in series to the output side of the full-wave rectifier circuit 4, and the second switching element Q2 and the diode D2 are connected in series to the load 9. Has been. With this configuration, the converter 5 has a circuit configuration including a component as a step-up converter and a component as a step-down converter.

Specifically, when the output voltage detection value Vo is less than the input voltage detection value Vin, the power supply control unit 2 always turns on the first switching element Q1 and switches the second switching element Q2. Therefore, when the output voltage detection value Vo is equal to or higher than the input voltage detection value Vin, the second switching element Q2 is always turned off and the first switching element Q1 is switched. It works as a step-down converter.

During the step-up control operation, the power supply control unit 2 always turns on the first switching element Q1 to perform the switching operation of the second switching element Q2. Therefore, the reactor current IL flowing through the reactor L corresponds to the input current Iin. It will be a thing. Further, during the step-down control operation, the power supply control unit 2 always turns off the second switching element Q2 and performs the switching operation of the first switching element Q1, so that the reactor current IL flowing through the reactor L becomes the output current Io. It will be compatible. Therefore, the current detection circuit 6 detects the current from which the switching frequency component of the input current Iin after full-wave rectification has been removed during the boost control operation, and before the current ripple of the output current Io is removed during the buck control operation. Current is detected.

As shown in FIG. 2, the power supply control unit 2 controls the output control amount I for controlling the output voltage Vdc to a desired value from the deviation between the voltage Vo detected by the output voltage detection circuit 8 and the target output voltage Vo *. The output control amount calculation unit 21 for calculating **, the voltage Vin detected by the input voltage detection circuit 7 and the voltage Vo detected by the output voltage detection circuit 8 are compared, and the converter 5 is operated for boost control. Or the comparison / determination unit 22 for determining whether to perform the step-down control operation, the selector 23 for selecting the operation of the next stage, and the selector 23 selects the step-up control operation for the converter 5 based on the determination result of the comparison / determination unit 22. In this case, the step-down control operation of the converter 5 is selected by the step-up control peak current calculation unit 24a for setting the peak current Iref * of the converter 5 from the output control amount I ** and the selector 23. In this case, the step-down control peak current calculation unit 24b for setting the peak current Iref * during the step-down control operation of the converter 5 from the output control amount I **, the reactor current IL and the peak current Iref * of the step-up control operation or step-down control. The peak current control unit 25a or the peak current control unit 25b that performs peak current control from the peak current Iref * of the operation and the output of the peak current control unit 25a or the peak current control unit 25b according to the determination result of the comparison determination unit 22 respectively. And an on / off signal generator 26 for selecting a signal and outputting a control signal to the switching elements Q1 and Q2.

Note that the on / off signal generator 26 determines whether the switch control unit 26a and the switch control unit 26b correspond to the peak current control unit 25a and the peak current control unit 25b, and the determination result of the comparison determination unit 22, respectively. A selector 26c that selects an output signal of the switch control unit 26b and switches a control signal output to the switching elements Q1 and Q2.

The power supply control unit 2 is obtained based on the value obtained corresponding to the input current Iin after full-wave rectification during the step-up control operation, and corresponding to the output current Io during the step-down control operation. The target reactor current IL *, which is the control target for the reactor current IL, is set based on each value. The power supply controller 2 can optimally control the phase and waveform of the input current Iin by controlling the reactor current IL to be the target reactor current IL *. Details of how to obtain the target reactor current IL * will be described later.

Next, the operation of the power supply control unit 2 will be described with reference to FIGS.
First, the power supply control unit 2 resistance-divides the input voltage detection value Vin detected by dividing the pulsating voltage | vac | by the input voltage detection circuit 7 and the output voltage vdc by the output voltage detection circuit 8. Based on the comparison with the detected output voltage value Vo, the step-up control operation and the step-down control operation of the converter 5 are switched. Here, during the step-up control operation, converter 5 functions as a step-up converter, and during step-down control operation, converter 5 functions as a step-down converter.

Further, the power supply control unit 2 performs on / off control of the switching elements Q1 and Q2 of the converter 5 by using the detection signals Vin, Vo, and IL described above, so that the power supply control unit 2 can perform both the step-up control operation and the step-down control operation. The PFC control function for controlling the input current Iin after full-wave rectification by the full-wave rectifier 4 is provided so that the alternating-current input current Iac has substantially the same phase and waveform as the alternating-current input voltage Vac.

In the PFC control described above, the target input current Iin *, which is a control target value when controlling the input current Iin, has the same pulsating waveform with the same phase as the pulsating voltage | Vac | for improving the power factor. However, it can be adjusted by controlling the reactor current IL flowing through the reactor L of the converter 5. Then, power supply control unit 2 controls switching elements Q1 and Q2 of converter 5 such that the average of reactor current IL per unit time matches target reactor current IL *.

As described above, since the current corresponding to the input current Iin flows through the reactor L during the boost control operation, the target reactor current IL * is set to a value proportional to the target input current Iin *. Further, during the step-down control operation, a current having a value corresponding to the output current Io flows through the reactor L. Therefore, the target reactor current IL * has a value proportional to the value obtained by converting the target input current Iin * into the output current. Set.

Therefore, the target reactor current IL * needs to be controlled so that the average of the reactor current IL per unit time becomes the target reactor current IL *. For this purpose, as shown in FIG. 4, a value that is twice the target reactor current IL * may be set as the peak current iref * by peak current control. That is, if the reactor current IL is raised at the moment when the reactor current IL reaches 0 and the reactor current IL is lowered at the moment when the peak current Iref * is reached, the reactor current IL becomes equal to the target reactor current IL *. Since the shortage of the reactor current IL that does not reach the target reactor current IL * due to the excess is compensated for, the average of the reactor current IL per unit time can be matched with the target reactor current IL *. From this, the relationship between the target reactor current IL * and the peak current Iref * is expressed by the following equation (1).

Iref * = 2 × IL * (1)

Next, the specific contents of the calculation control process of the power supply control unit 2 will be described with reference to the flowchart showing the calculation control process procedure of FIG.

When the power supply control unit 2 starts the control process, first, the input voltage detection value Vin detected by dividing the pulsating voltage | Vac | by the input voltage detection circuit 7 of the power supply main circuit unit 1 and the output voltage are detected. Each of the detected output voltage values Vo detected by resistance-dividing the output voltage Vdc by the detection circuit 8 is fetched, and the target output voltage Vo * indicating the control target value of the output voltage Vo is received from the host system (step 1 (S01)). ). Here, the target output voltage Vo * is received from the outside such as the host system, but is not limited to this and may be a predetermined constant.

Subsequently, the output control amount calculation unit 21 outputs the output control amount I ** for controlling the output voltage Vdc to a desired value by calculation such as PI control from the deviation between the output voltage detection value Vo and the target output voltage Vo *. Is calculated (step 2 (S02)).

Further, the comparison / determination unit 22 calculates the input voltage detection value Vin (instantaneous value) and the output voltage detection value Vo in order to obtain the peak current iref * corresponding to the circuit operation status in the power supply main circuit unit 1. Are compared to determine the current circuit operation status (whether it is a step-up control operation or a step-down control operation) in the power supply main circuit unit 1 (step 3 (S03)). If it is determined that the input voltage detection value Vin is less than the output voltage detection value Vo (Vin <Vo), it is determined that the operation is a step-up control operation, and the process proceeds to step 4 (S04). At the same time, during boost control, the comparison determination unit 22 connects the common contact c of the upstream selector 23 connected to the output side of the output control amount calculation unit 21 to the individual contact a on the boost control operation side. A signal for connecting the individual contact a on the boost control operation side of the selector 26c to the common contact c is sent. On the other hand, if the input voltage detection value Vin is equal to or higher than the output voltage detection value Vo (Vin ≧ Vo), it is determined that the operation is a step-down control operation, and the process proceeds to step 9 (S09). At the same time, in the step-down control operation, the comparison / determination unit 22 connects the common contact c of the selector 23 in the previous stage connected to the output side of the output control amount calculation unit 21 to the individual contact b on the step-down control operation side. Then, a signal for connecting the individual contact b on the step-down control operation side of the selector 26c in the subsequent stage to the common contact c is sent.

Next, in step 4 (S04), step-up control is performed in order to perform PFC control for controlling the input current Iin after full-wave rectification so that the AC input current Iac has substantially the same phase and waveform as the AC input voltage Vac. The target reactor current IL * is calculated, and in step 9 (S09), the step-down control target reactor current IL * is calculated. Here, as shown in the above-described equation (1), a value twice the target reactor current iL * is set as the peak current Iref *.

As described above, the current corresponding to the input current Iin flows through the reactor L during the step-up control operation, and the current corresponding to the output current Io flows during the step-down control operation. The method for calculating the target reactor current IL * is changed depending on whether the step-up control operation is performed or the step-down control operation is performed.

That is, when the comparison determination unit 22 determines that the input voltage detection value Vin is less than the output voltage detection value Vo (Vin <Vo), a boost control operation is performed (step 3 (S03)). During this boost control operation, a current corresponding to the input current Iin after full-wave rectification flows through the reactor L, so that the boost control target reactor current IL * controls a current corresponding to the input current Iin. . Accordingly, the boost control peak current calculation unit 24a first uses the target input current Iin *, which is the target value of the input current Iin, and the output control amount I ** described above, and the boost control target according to the following equation (2). Reactor current IL * is calculated.

IL * = Iin * × I ** (2)

However, in order to make the target input current iin * have the same phase as the input voltage detection value vin obtained by detecting the pulsating voltage | Vac | and the same pulsating waveform, the input voltage is replaced with the target input current Iin *. The detected value Vin may be used, and therefore the boost control target reactor current IL * during the boost control operation can be set by the following equation (3) (step 4 (S04)).

IL ** = Vin × I ** (3)

Therefore, the peak current Iref * can be expressed by the following equation (4) by substituting equation (3) into equation (1).

Iref * = 2 × IL * = 2 × Vin × I ** (4)

Subsequently, the boost control peak current calculation unit 24a further adds the ideal value Vin_ref of the input voltage generated by the power supply control unit 2 and the input voltage detection value to the peak current Iref * of the equation (4) in the peak current control. By multiplying the correction coefficient obtained by squaring the ratio with Vin, the boost control peak current Iref * in the peak current control expressed by the following equation (5) is calculated (step 5 (S05)).

Iref * = 2 × IL *
= 2 × Vin × I *** × (Vin_ref / Vin) ² (5)

In addition, the correction coefficient (Vin_ref / Vin) ² of the above formula (5) will be described later.

Next, in order to perform peak current control in the peak current control unit 25a, the reactor current IL detected by the current detection circuit 6 of the power supply main circuit unit 1 is fetched (step 6 (S06)), and the reactor current IL and Peak current control is performed using the peak current Iref * obtained by the boost control peak current calculation unit 24a (step 7 (S07)).

In this peak current control, as shown in FIG. 4, so-called Bang-Bang control for controlling the reactor current IL between the value of 0 and the peak current Iref * obtained by the equation (4) is performed. Do.

That is, in the step-up control operation, the peak current control unit 25a is configured so that the reactor current IL is equal to the above-described equation (4) in the state where the first switching element Q1 is always turned on in the on / off signal generation unit 26. The second switching element Q2 is controlled to be turned on at the moment when the boost control peak current Iref * obtained in step S3 is reached, and the reactor current IL is reduced. At the moment when the reactor current IL reaches zero, the second switching element Q2 is turned on. A signal for controlling the operation of the switch control unit 26a is output so as to increase the reactor current IL by controlling the second switching element Q2 to be off (step 7 (S07)).

In response to this, the switch control unit 26a supplies a switch signal for turning on / off to the second switching element Q2 constituting the step-up arm and a switch signal for always turning on the first switching element Q1. Generate and output (step 8 (S08)).

On the other hand, when the comparison determination unit 22 determines that the input voltage detection value Vin is equal to or higher than the output voltage detection value Vo (Vin ≧ Vo), a step-down control operation is performed (step 3 (S03)). During this step-down control operation, a current corresponding to the output current Io flows through the reactor L, so the step-down control target reactor current IL * controls the current corresponding to the output current Io. Therefore, the step-down control peak current calculation unit 24b first calculates the step-down control target reactor current IL * by the following equation (6) using the output current Io and the output control amount I ** described above (step 10 ( S10)).

IL ** = Io × I ** (6)

Assuming that the power conversion efficiency of the power supply main circuit unit 1 is 100%, the input power and the output power are equal from the law of energy conservation, so the output current Io is the target input current Iin *, the input voltage detection value Vin, and the output It can convert by following Formula (7) using the voltage detection value Vo.

Io = (Vin × Iin *) / Vo (7)

Therefore, step-down control target reactor current IL * can be expressed by equation (8) using equations (5) and (6).

IL * = (Vin × Iin *) / Vo × I ** (8)

Further, in order to make the target input current Iin * to have the same phase and the same pulsating waveform as the input voltage detection value Vin detected by dividing the pulsating voltage | Vac | by resistance, the target input current Iin * is replaced with the target input current Iin *. The input voltage detection value Vin may be used, and therefore the step-down control target reactor current IL * during the step-down control operation can be set by the following equation (9) (step 9 (S09)).

IL * = Vin ² / Vo × i ** (9)

Therefore, the peak current Iref * can be expressed by the following equation (10) by substituting equation (9) into equation (1).
Iref * = (2 × Vin ² / Vo) × I ** (10)

Subsequently, in the peak current control, the step-down control peak current calculation unit 24b adds the ideal value Vin_ref of the input voltage generated by the power supply control unit 2 and the input voltage detection value to the peak current Iref * of the equation (9). The step-down control peak current Iref * in the peak current control represented by the following equation (11) is calculated by multiplying the correction coefficient obtained by squaring the ratio with Vin (step 10 (S10)).

Iref * = 2 × IL *
= (2 × Vin ² / Vo) × I ** × (Vin_ref / Vin) ²
(11)

Note that the correction coefficient (Vin_ref / Vin) ² of the above equation (11) will be described later.

Next, in order to perform peak current control in the peak current control unit 25b, the reactor current IL detected by the current detection circuit 6 of the power supply main circuit unit 1 is fetched (step 11 (S11)), and the reactor current IL and Peak current control is performed using the peak current Iref * obtained by the step-down control peak current calculation unit 24b (step 12 (S12)).

In this peak current control, as shown in FIG. 4, so-called Bang-Bang control for controlling the reactor current IL between the value of 0 and the peak current Iref * obtained by the equation (9) is performed. Do.

That is, in the case of the step-down control operation, the peak current control unit 25b is configured so that the reactor current IL is equal to the above equation (9) in the state where the second switching element Q2 is always turned off in the on / off signal generation unit 26. At the moment when the step-down control peak current Iref * obtained in step S3 is reached, the first switching element Q1 is controlled to be turned off, the reactor current IL is decreased, and at the moment when the reactor current IL reaches zero, The switching element Q1 is controlled to be turned on, and a signal for controlling the operation of the switch control unit 26b is output so as to increase the reactor current IL (step 12 (S12)).

In response to this, the switch control unit 26b generates an on / off switch signal for the first switching element Q1 constituting the step-down arm and a switch signal for always turning off the second switching element Q2. (Step 13 (S13)).

According to these procedures, the reactor current is controlled during the step-up and step-down control operations of the converter 5, the input current waveform can be brought close to the input voltage waveform, and power factor improvement control is executed.

The correction coefficient (Vin_ref / Vin) ² used in the equations (5) and (11) will be described below.
The peak current Iref * in the conventional peak current control is set by the above-described equation (4). However, when control is performed using the peak current Iref * of Equation (4), when a voltage dip or the like that decreases the input voltage occurs when another device connected to the same AC line is activated, the input voltage Since the detection value Vin also decreases, the peak current Iref * also decreases.

FIG. 6 is a waveform diagram showing fluctuations in the output voltage detection value Vo when the input voltage fluctuates when control is performed using the conventional peak current iref * represented by Expression (4). In FIG. 6, the horizontal axis indicates time, the upper waveform indicates the peak current Iref *, and the lower waveform indicates the output voltage detection value Vo. Thus, it can be seen that when the control is performed using the peak current Iref * shown in the equation (4), the output voltage detection value Vo is greatly reduced because the energy required for the output is insufficient.

This is because the input voltage detection value Vin is the gain of the power supply main circuit unit 1 regardless of the step-up control operation and the step-down control operation, and the gain of the power supply control unit 2 as shown in the equation (4). This is due to the fact that That is, when considering a round-trip transfer function of the power supply, when the input voltage fluctuates, the influence is given by the square of Vin.

In order to prevent this phenomenon, control may be performed so that the gain of the round trip transfer function of the power supply does not change. That is, when the input voltage can be controlled in an ideal sine wave form, the gain Gr of the power supply round trip function is expressed by the following equation (12) using the ideal value Vin_ref of the input voltage.

Gr = Vin_ref × 2 × Vin_ref × I ** (12)

On the other hand, the gain G of the circuit transfer function of the power supply when the input voltage fluctuates due to a voltage dip or the like is expressed by the following equation (13) using the input voltage detection value Vin.

G = Vin × 2 × Vin × i ** (13)

When the input voltage fluctuates, it is necessary to change the equation (13) to the equation (12) so that the gain of the one-round transfer function does not change. Becomes the following equation (14).

Gm = vin × 2 × vin × i ** × (Vin_ref / Vin) ²
(14)

Therefore, when the input voltage fluctuates, it can be corrected by multiplying (Vin_ref / Vin) ² of the above formula (14) by the peak current iref * of the power supply control unit 2.

FIG. 7 shows fluctuations in the detected output voltage Vo when the input voltage fluctuates when controlled using the peak current iref * shown in the equation (5) or the equation (11) corrected with the correction coefficient (Vin_ref / Vin) ^2. FIG. In FIG. 7, the horizontal axis indicates time, the upper waveform indicates the peak current iref *, and the lower waveform indicates the output voltage detection value Vo. As described above, when the input voltage detection value Vin is decreased, the peak current iref * in FIG. 7 in the case where the correction is performed is larger than that in FIG. 6 in the case where the correction is not performed. As a result, fluctuations in the output voltage detection value Vo are suppressed.

In the first embodiment, the waveform shape of the peak current iref * is one of the major features. When the peak current iref * is controlled by formula (5) or formula (11), when the input voltage detection value Vin fluctuates from the normal level, the peak current iref * waveform is set larger than the normal level and controlled. When the voltage detection value Vin fluctuates from the normal level, the waveform of the peak current iref * is controlled to be set smaller than the normal level.

The correction coefficient (Vin_ref / Vin) ² in the equations (5) and (11) is characterized in that the control is always performed regardless of the presence or absence of the input voltage fluctuation. This coefficient is 1, which is the conventional peak current iref * expression (4). If there is a fluctuation in the input voltage, it is corrected according to this coefficient regardless of the magnitude of the fluctuation, and the fluctuation control is detected by detecting the fluctuation range. There is no need to switch.

Here, the ideal control method is performed by multiplying the correction coefficient (Vin_ref / Vin) ² of the equation (5) or the equation (11) of the peak current iref *. However, even if the control accuracy is rough, In a case where the input voltage detection value Vin decreases, the peak current iref * is increased by a predetermined value or a correction coefficient corresponding to a predetermined value depending on a value that decreases. Further, when the input voltage detection value Vin increases, the control may be such that the peak current iref * is reduced by a constant value or a predetermined correction coefficient corresponding to the increased value. Any control is possible as long as the value of the peak current iref * is controlled to be opposite to the change in the input voltage fluctuation.

Next, a method of generating the ideal value Vin_ref of the input voltage detection value Vin generated by the power supply control unit 2 will be described with reference to FIG.

The power supply control unit 2 always captures the input voltage detection value Vin (instantaneous value). Since the input voltage detection value Vin has a signal shape obtained by full-wave rectification of the AC input voltage Vac, as shown in FIG. 8 illustrated as an example at 50 Hz, the input voltage detection value Vin has a waveform shape folded at 0V. The input voltage detection value Vin (instantaneous value) is the smallest value near 0 V, and the frequency of the AC input voltage Vac can be determined by the time interval between this minimum value and the minimum value at the next timing.

Also, it is possible to detect the maximum value during the time period during which the time interval is measured, thereby determining whether the system is a 100V system, a 200V system, or a 242V system.

Based on the above two determinations, a count is made from the minimum value of the input voltage detection value Vin for each sampling period of input voltage detection inside a control IC such as a microcomputer, and a count value (cnt) prepared in advance in a table inside the microcomputer. ) And the ideal value (Vin_ref) of a sine wave that has a one-to-one correspondence.

Here, a method of generating an ideal value of a sine wave (Vin_ref) using a table stored in a control IC such as a microcomputer is shown, but the present invention is not limited to this. A method of calculating a wave to obtain an ideal value (Vin_ref) of the sine wave may be used.

In the first embodiment, in the power supply control unit 2, the output control amount calculation unit 21, the comparison determination unit 22, the selector 23, the step-up control peak current calculation unit 24a, the step-down control peak current calculation unit 24b, the peak current Although the

control units

25a and 25b and the on / off signal generation unit 26 are divided into blocks for each function, such control of each function can be realized by a control IC such as a microcomputer using a control program.

In the first embodiment, the case where an H-type bridge buck-boost converter is used as the converter has been described. However, the present invention can also be applied to a simple boost converter in which the output voltage is always controlled to be larger than the input voltage. Needless to say, the present invention can be applied to all converters that control the peak current of the reactor.

As described above, according to the first embodiment, the power conversion device including the H-type bridge buck-boost converter 5 that converts AC input into DC output includes the power supply control unit 2 that controls the reactor current IL. In this power supply control unit 2, AC is controlled by controlling the switching elements Q <b> 1 and Q <b> 2 of the converter 5 while switching between step-up control and step-down control based on a comparison of the magnitude of the input voltage detection value Vin and the output voltage detection value Vo. Power factor correction control (PFC) is performed to bring the waveform of the input current Iac closer to the waveform of the AC input voltage Vac. At that time, the calculation method is switched between the step-up control operation and the step-down control operation so that the target input current Iin * in the PFC control has the same phase as the pulsating voltage | Vac | and the same pulsating waveform.

That is, since a current corresponding to the input current Iin after full-wave rectification flows through the reactor L during the boost control operation, the boost control target reactor current IL * is controlled based on the equation (6), and during the step-down control operation, Since a current corresponding to the output current Io flows through the reactor L, the step-down control target reactor current IL * is adjusted to be controlled based on the equation (9), thereby adjusting the reactor current IL flowing through the reactor L, Since the AC input current Iac has the same phase and waveform as the AC input voltage Vac, the power factor can be improved. In addition, since the boost control and step-down control peak current Iref * is multiplied by the square of the ratio of the ideal value (Vin_ref) of the input voltage and the detected input voltage detection value Vin, the output waveform even when the input voltage fluctuates. Fluctuations can be suppressed. Furthermore, since this power converter is composed of a single-stage converter 5 and uses peak current control, the number of components is small, low cost, and high efficiency can be realized.

In the first embodiment, the control method of the reactor current IL is the peak current control method. However, the present invention is not limited to such a peak current control method. For example, as shown in FIG. 9, the target reactor current iL * On the other hand, it is possible to apply a hysteresis comparator control method in which two upper and lower peak currents Iref1 * and Iref2 * having a constant width ± ΔT are determined and the reactor current IL is increased or decreased between the two peak currents Iref1 * and Iref2 *. Further, as shown in FIG. 10, the peak current Iref * is determined so that the target reactor current IL * is located at the center position between the upper limit peak current Iref1 * and the lower limit peak current Iref2 * of the divided voltage value. It is also possible to apply a window comparator control system that increases or decreases the reactor current IL between the peak currents Iref1 * and Iref2 *.

As described above, according to the power conversion device and the control method thereof according to Embodiment 1, the power supply control unit of the converter that performs the power factor improvement control by controlling the reactor current is supplied with the input voltage generated by the power supply control unit. When the control is performed by setting the peak current multiplied by the correction coefficient obtained by squaring the ratio between the ideal value and the detected value of the input voltage, the square of this ratio is 1 when there is no input voltage fluctuation. When the power factor improvement control is performed as usual and the input voltage fluctuates, the ratio between the ideal input voltage value and the detected input voltage value changes, and the power factor corresponding to the amount of change in this ratio Since the improvement control is executed, there is an effect that an appropriate correction according to the input voltage fluctuation is possible.

In the description of the above embodiment, the case where the converter 5 includes the diodes D1 and D2 and the switching elements Q1 and Q2 has been described. However, the circuit block diagram of the power conversion device according to another embodiment of FIG. As shown in the diagram, the converter 51 may be configured to change the diodes D1 and D2 to switching elements Q3 and Q4 such as FET elements and IGBT elements. When the boost control operation is performed, on / off of the switching elements Q2 and Q4 is reversed. Thus, during the step-down control operation, the same effect can be obtained by the synchronous rectification method in which the switching elements Q1 and Q3 are turned on and off with reverse logic.

Embodiment 2. FIG.
FIG. 12 is a circuit block diagram illustrating an overall configuration of the power conversion device according to the second embodiment, and FIG. 13 is a circuit block diagram illustrating a configuration of a power supply control unit of the power conversion device. In the power conversion device according to the second embodiment, as shown in FIG. 12, an LED lighting apparatus in which a plurality of LEDs (Light Emitting Diodes) 90 are connected in series is connected to the power supply main circuit unit 1 as a load. Yes.

LED is usually suitable for current control due to its characteristics. For this reason, in this Embodiment 2, the LED current detection circuit 91 is added as a detection circuit for detecting LED current ILED which flows into LED with respect to the circuit structure of FIG. 1 (FIG. 1). As shown in FIG. 13, in the power supply control unit 20, the output control amount calculation unit 21 uses the LED current ILED detected by the LED current detection circuit 91 instead of the output voltage detection value Vo and the target output voltage Vo *, The target output current ILED * is input. Since other components are the same as those in the first embodiment, the description thereof is omitted.

Using this configuration, the LED current ILED flowing through the LED 90 can be controlled by controlling the reactor current IL as in the first embodiment. In addition, when the dimming function for adjusting the amount of light is mounted on the LED illumination, the dimming function is also realized by making the target output current ILED * variable from an external device. be able to.

In addition, when control is performed with the peak current Iref * of the conventional formula (4), there is a concern that when the input voltage fluctuates, the output current fluctuates and the LED light quantity flickers and is visually recognized. In order to solve this problem, it was necessary to take measures by increasing the capacity of the output capacitor. Therefore, the circuit size has been increased and the cost has been increased. However, by using Equation (5) or Equation (11) for the peak current Iref *, it is possible to suppress flickering of the LED light amount when the input voltage fluctuates without increasing the capacity of the output capacitor.

Moreover, the connection method of the LED serving as the load 90 is not limited to simply connecting in series, and may be parallel connection or series-parallel connection. The load 90 may be another light source such as an organic EL or a laser diode.

Thus, according to the power conversion device according to the second embodiment, when a plurality of LEDs are provided as loads, the LED current ILED detected by the LED current detection circuit is fed back to the power supply control unit, and the output control amount The calculation unit controls the LED current ILED to be the target output current ILED *, and the switching elements Q1 and Q2 are turned on / off by the peak current calculation unit, the peak current control unit, and the on / off signal generation unit, as in the first embodiment. By controlling, it is possible to suppress flickering of the LED light amount even when the input voltage fluctuates.

In the present invention, it is possible to freely combine the respective embodiments within the scope of the invention, and to appropriately modify and omit the respective embodiments.

In the drawings, the same reference numerals indicate the same or corresponding parts.

1,10 power supply main circuit section, 2,20 power supply control section, 3 AC power supply, 4 full-wave rectifier circuit, 5,51 H-bridge buck-boost converter (converter), 6 current detection circuit, 7 input voltage detection circuit, 8 Output voltage detection circuit, 9 load, 21 output control amount calculation unit, 22 comparison judgment unit, 23 selector, 24a peak current calculation unit for boost control, 24b peak current calculation unit for step-down control, 25a, 25b peak current control unit, 26 ON / OFF signal generator, 26a, 26b, switch controller, 26c selector, 90 LED, 91 LED current detection circuit.

Claims

A full-wave rectifier circuit for full-wave rectification of the AC voltage of the AC power source, an input voltage detection circuit for detecting an input voltage after full-wave rectification by the full-wave rectifier circuit, a switching element and a reactor, and the input voltage A converter for converting to a target output voltage, an output voltage detection circuit for detecting an output voltage after voltage conversion by the converter, and a power supply main circuit unit having a current detection circuit for detecting a reactor current flowing in the reactor;
Power factor improvement to control the output voltage by controlling the switching element on and off based on the input voltage, the output voltage and the reactor current, and to control the reactor current to bring the input current waveform closer to the input voltage waveform A power control unit for performing control,
When the input voltage detection circuit detects a fluctuation in which the input voltage is lower than normal, the power supply control unit controls the reactor current to be set larger than normal, and the input voltage is higher than normal. When detecting the fluctuation | variation which rises, the said reactor current is set smaller than normal time, and it controls, The power converter device characterized by the above-mentioned.
The control of the reactor current is performed by calculating a target reactor current, and performing peak current control so that the reactor current matches the target reactor current, and the ideal value of the input voltage and the detected input voltage. The power converter according to claim 1, wherein control is performed by setting a peak current multiplied by a correction coefficient obtained by squaring the ratio.
The power converter according to claim 1 or 2, wherein the converter is an H-type bridge buck-boost converter having two switching elements, two diodes, and a reactor.
The power converter according to claim 1 or 2, wherein the converter is an H-type bridge buck-boost converter having four switching elements and a reactor.
The said power supply control part changes the said target reactor current by the case where the said input voltage is less than the said output voltage, and the case where the said input voltage is more than the said output voltage. Power converter.
3. The power conversion according to claim 2, wherein the ideal value of the input voltage is determined from a minimum value of the input voltage and determined from a preset input voltage ideal value table based on the count value. apparatus.
3. The power conversion device according to claim 2, wherein the power supply control unit uses hysteresis control as a control method in the case of performing control so that the reactor current matches the target reactor current.
3. The power converter according to claim 2, wherein window comparator control is used as a control method when the power source control unit performs control so that the reactor current matches the target reactor current.
The power source main circuit unit is connected to an LED as a load, and is provided with an LED current detection circuit that detects an LED current flowing through the LED, and the power source control unit is detected by the LED current detection circuit. 9. The power conversion device according to claim 1, wherein current control of the LED is performed based on an LED current. 10.
A full-wave rectifier circuit for full-wave rectification of the AC voltage of the AC power source, an input voltage detection circuit for detecting an input voltage after full-wave rectification by the full-wave rectifier circuit, a switching element and a reactor, and the input voltage A converter for converting to a target output voltage, an output voltage detection circuit for detecting an output voltage after voltage conversion by the converter, and a power supply main circuit unit having a current detection circuit for detecting a reactor current flowing in the reactor; Power factor improvement to control the output voltage by controlling the switching element on and off based on the input voltage, the output voltage and the reactor current, and to control the reactor current to bring the input current waveform closer to the input voltage waveform A control method of a power conversion device including a power supply control unit that performs control,
An input voltage detection step in which the input voltage detection circuit detects the input voltage;
An output voltage detection step in which the output voltage detection circuit detects the output voltage;
When the power supply control unit detects a fluctuation in which the input voltage is lower than normal in the input voltage detection step, the reactor current is controlled to be set larger than normal, and the input voltage is increased from normal. When detecting the fluctuation, a current control step for performing control by setting the reactor current to be smaller than normal; and
The control method of the power converter device characterized by the above-mentioned.