WO2021038882A1 - 電力変換装置 - Google Patents

電力変換装置 Download PDF

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Publication number
WO2021038882A1
WO2021038882A1 PCT/JP2019/034300 JP2019034300W WO2021038882A1 WO 2021038882 A1 WO2021038882 A1 WO 2021038882A1 JP 2019034300 W JP2019034300 W JP 2019034300W WO 2021038882 A1 WO2021038882 A1 WO 2021038882A1
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WIPO (PCT)
Prior art keywords
power supply
switching element
current
control unit
voltage
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PCT/JP2019/034300
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English (en)
French (fr)
Japanese (ja)
Inventor
厚司 土谷
和徳 畠山
啓介 植村
Original Assignee
三菱電機株式会社
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Application filed by 三菱電機株式会社 filed Critical 三菱電機株式会社
Priority to PCT/JP2019/034300 priority Critical patent/WO2021038882A1/ja
Priority to JP2021541964A priority patent/JPWO2021038882A1/ja
Publication of WO2021038882A1 publication Critical patent/WO2021038882A1/ja

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
    • H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
    • H02M7/12—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode

Definitions

  • the present invention relates to a power conversion device that converts AC power into DC power.
  • the power converter is a converter that converts the AC voltage supplied from the AC power supply into a DC voltage and outputs the converted DC voltage to loads such as inverters and motors.
  • the power conversion device includes a rectifier circuit having a switching element such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), and by controlling the on / off of the switching element, power conversion can be performed with high efficiency.
  • Patent Document 1 discloses a technique for switching on / off of a switching element according to the polarity of an AC voltage supplied from an AC power supply.
  • the switching element described in Patent Document 1 since the power conversion device described in Patent Document 1 switches the switching element on and off according to the polarity of the AC voltage, the switching element becomes excessive in a short time depending on the relationship between the AC voltage and the bus voltage, that is, the DC voltage. Voltage may be applied. When an excessive voltage is applied to the switching element in a short time, voltage ringing occurs in the switching element, which causes an increase in noise and an increase in loss when the switching element is switched. Further, in the power conversion device described in Patent Document 1, when the DC voltage is larger than the AC voltage, when the switching element is switched on and off depending on the polarity of the AC voltage, a current flows from the DC side to the AC side, and the AC power supply It may cause reverse current to the current, destruction of circuit elements, etc.
  • the present invention has been made in view of the above, and an object of the present invention is to obtain a power conversion device capable of reducing noise and loss during switching of a switching element of a rectifier circuit.
  • the power conversion device has a reactor having a first end portion and a second end portion, and the first end portion is connected to an AC power source.
  • a rectifier circuit that has one or more arms connected in series with switching elements connected to the second end of the reactor and connected in parallel with diodes, and converts the AC voltage output from the AC power supply into a DC voltage, and a rectifier. It includes a detection unit that detects a physical quantity indicating the operating state of the circuit.
  • the power conversion device has the effect of being able to reduce noise and loss during switching of the switching element of the rectifier circuit.
  • FIG. 1 Schematic cross-sectional view showing a schematic structure of a MOSFET constituting the switching element according to the first embodiment.
  • a time chart showing the timing at which the control unit turns on the switching element in the power conversion device according to the first embodiment.
  • FIG. The figure which shows the state of the current which flows at the time of steps S13 and S17 of FIG. 3 in the power conversion apparatus which concerns on Embodiment 1.
  • FIG. The figure which shows the state of the current which flows at the time of step S15 of FIG. 3 in the power conversion apparatus which concerns on Embodiment 1.
  • FIG. The figure which shows the loss which occurs in the switching element of the rectifier circuit of the power conversion apparatus which concerns on Embodiment 1.
  • a flowchart showing an operation in which the control unit of the power conversion device according to the first embodiment turns on and off the switching element.
  • a flowchart showing an operation in which the control unit of the power conversion device according to the second embodiment turns on and off the switching element.
  • a flowchart showing an operation in which the control unit of the power conversion device according to the third embodiment turns on and off the switching element.
  • FIG. 1 is a diagram showing a configuration example of the power conversion device 100 according to the first embodiment of the present invention.
  • the power conversion device 100 is a power supply device having an AC / DC conversion function that converts the AC power supplied from the AC power supply 1 into DC power and applies it to the load 50 by using the rectifier circuit 3.
  • the power conversion device 100 includes a reactor 2, a rectifier circuit 3, a smoothing capacitor 4, a power supply voltage detection unit 5, a power supply current detection unit 6, a bus voltage detection unit 7, and a load current.
  • a detection unit 8, a zero cross detection unit 9, and a control unit 10 are provided.
  • the reactor 2 includes a first end portion and a second end portion, and the first end portion is connected to the AC power supply 1.
  • the rectifier circuit 3 converts the AC voltage output from the AC power supply 1 into a DC voltage.
  • the rectifier circuit 3 is a circuit including two arms in which two switching elements in which diodes are connected in parallel are connected in series, and two arms are connected in parallel.
  • the rectifier circuit 3 includes a first arm 31 which is a first circuit and a second arm 32 which is a second circuit.
  • the first arm 31 includes a switching element 311 and a switching element 312 connected in series.
  • a parasitic diode 311a is formed on the switching element 311.
  • the parasitic diode 311a is connected in parallel between the drain and the source of the switching element 311.
  • a parasitic diode 312a is formed on the switching element 312.
  • the parasitic diode 312a is connected in parallel between the drain and the source of the switching element 312.
  • Each of the parasitic diodes 311a and 312a is a diode used as a freewheeling diode.
  • the switching element 311 may be referred to as a first switching element
  • the switching element 312 may be referred to as a second switching element.
  • the second arm 32 includes a switching element 321 and a switching element 322 connected in series.
  • the second arm 32 is connected in parallel to the first arm 31.
  • a parasitic diode 321a is formed on the switching element 321.
  • the parasitic diode 321a is connected in parallel between the drain and the source of the switching element 321.
  • a parasitic diode 322a is formed on the switching element 322.
  • the parasitic diode 322a is connected in parallel between the drain and the source of the switching element 322.
  • Each of the parasitic diodes 321a and 322a is a diode used as a freewheeling diode.
  • the power conversion device 100 includes a first wiring 501 and a second wiring 502, each of which is connected to the AC power supply 1, and a reactor 2 arranged in the first wiring 501.
  • the first arm 31 includes a switching element 311 which is a first switching element, a switching element 312 which is a second switching element, and a third wiring 503 having a first connection point 506.
  • the switching element 311 and the switching element 312 are connected in series by the third wiring 503.
  • the first wiring 501 is connected to the first connection point 506.
  • the first connection point 506 is connected to the AC power supply 1 via the first wiring 501 and the reactor 2.
  • the first connection point 506 is connected to the second end of the reactor 2.
  • the second arm 32 includes a switching element 321 which is a third switching element, a switching element 322 which is a fourth switching element, and a fourth wiring 504 including a second connection point 508.
  • the 321 and the switching element 322 are connected in series by the fourth wiring 504.
  • a second wiring 502 is connected to the second connection point 508.
  • the second connection point 508 is connected to the AC power supply 1 via the second wiring 502.
  • the smoothing capacitor 4 is a capacitor connected in parallel to the rectifier circuit 3, specifically, the second arm 32.
  • one end of the switching element 311 is connected to the positive side of the smoothing capacitor 4
  • the other end of the switching element 311 and one end of the switching element 312 are connected
  • the other end of the switching element 312 is the negative of the smoothing capacitor 4. It is connected to the side.
  • the switching elements 311, 312, 321 and 322 are composed of MOSFETs.
  • the switching elements 311, 312, 321 and 322 are composed of a wide band gap (WBG) semiconductor such as gallium nitride (GaN), silicon carbide (Silicon Carbide: SiC), diamond or aluminum nitride.
  • WBG wide band gap
  • GaN gallium nitride
  • SiC silicon carbide
  • a MOSFET can be used.
  • the withstand voltage resistance is high and the allowable current density is also high, so that the module can be miniaturized. Since the WBG semiconductor has high heat resistance, it is possible to miniaturize the heat radiating fins of the heat radiating portion.
  • the control unit 10 is a switching element of the rectifier circuit 3 based on the signals output from the power supply voltage detection unit 5, the power supply current detection unit 6, the bus voltage detection unit 7, the load current detection unit 8, and the zero cross detection unit 9, respectively. Generates a drive signal that operates 311, 312, 321 and 322.
  • the power supply voltage detection unit 5 is a voltage detection unit that detects the power supply voltage Vs, which is the voltage value of the output voltage of the AC power supply 1, and outputs an electric signal indicating the detection result to the control unit 10.
  • the power supply current detection unit 6 is a current detection unit that detects the power supply current Is, which is the current value of the current output from the AC power supply 1, and outputs an electric signal indicating the detection result to the control unit 10.
  • the power supply current Is is the current value of the current flowing between the AC power supply 1 and the rectifier circuit 3.
  • the bus voltage detection unit 7 is a voltage detection unit that detects the bus voltage Vdc and outputs an electric signal indicating the detection result to the control unit 10.
  • the bus voltage Vdc is a voltage obtained by smoothing the output voltage of the rectifier circuit 3 with the smoothing capacitor 4.
  • the load current detection unit 8 is a current detection unit that detects the load current Idc, which is the current value of the current flowing through the load 50, and outputs an electric signal indicating the detection result to the control unit 10.
  • the zero cross detection unit 9 outputs a High or Low zero cross (ZC) signal corresponding to the power supply voltage Vs of the AC power supply 1 to the control unit 10.
  • ZC High or Low zero cross
  • the zero-cross detection unit 9 outputs, for example, a Low when the power supply voltage Vs is positive, and a High zero-cross signal when the power supply voltage Vs is negative.
  • the zero-cross detection unit 9 may invert High and Low and output a High zero-cross signal when the power supply voltage Vs is positive and a Low zero-cross signal when the power supply voltage Vs is negative.
  • the power supply voltage detection unit 5, the power supply current detection unit 6, the bus voltage detection unit 7, the load current detection unit 8, and the zero cross detection unit 9 may be simply referred to as detection units. Further, the power supply voltage Vs detected by the power supply voltage detection unit 5, the power supply current Is detected by the power supply current detection unit 6, the bus voltage Vdc detected by the bus voltage detection unit 7, and the load current detection unit 8 are detected. The load current Idc and the zero-cross signal output from the zero-cross detection unit 9 may be referred to as a physical quantity indicating an operating state of the rectifying circuit 3.
  • the control unit 10 controls the on / off of the switching elements 311, 312, 321 and 322 according to the power supply voltage Vs, the power supply current Is, the bus voltage Vdc, the load current Idc, and the zero cross signal.
  • the control unit 10 controls the on / off of the switching elements 311, 312, 321 and 322 by using at least one of the power supply voltage Vs, the power supply current Is, the bus voltage Vdc, the load current Idc, and the zero cross signal. May be good.
  • the switching elements 311, 321 connected to the positive side of the AC power supply 1, that is, the positive electrode terminal of the AC power supply 1 may be referred to as upper switching elements.
  • the switching elements 312 and 322 connected to the negative side of the AC power supply 1, that is, the negative electrode terminal of the AC power supply 1, may be referred to as a lower switching element.
  • the upper switching element and the lower switching element operate complementarily. That is, when one of the upper switching element and the lower switching element is on, the other is off.
  • the switching elements 311, 312 constituting the first arm 31 are driven by a drive signal generated by the control unit 10, as will be described later.
  • the on or off operation of the switching elements 311, 312 according to the drive signal is also referred to as a switching operation below.
  • the short circuit of the smoothing capacitor 4 is referred to as a capacitor short circuit.
  • Capacitor short circuit is a state in which the energy stored in the smoothing capacitor 4 is released and the current is regenerated in the AC power supply 1.
  • the switching elements 321 and 322 constituting the second arm 32 are turned on or off by the drive signal generated by the control unit 10.
  • the switching elements 321 and 322 are basically turned on or off depending on the polarity of the power supply voltage, which is the polarity of the voltage output from the AC power supply 1. Specifically, when the power supply voltage polarity is positive, the switching element 322 is on and the switching element 321 is off, and when the power supply voltage polarity is negative, the switching element 321 is on and switching. Element 322 is off.
  • FIG. 1 shows a drive signal for controlling on / off of the switching elements 311, 312, 321 and 322 with arrows directed from the control unit 10 to the rectifier circuit 3.
  • the parasitic diodes 311a, 312a, 321a, and 322a are described for the switching elements 311, 312, 321 and 322, but this is an example and the switching elements 311, 312, 321 , 322 and a diode such as a rectifier diode and a Schottky barrier diode may be separately connected in parallel.
  • the rectifier circuit 3 is configured to include four switching elements 311, 312, 321 and 322, but the second arm 32 has two switching elements deleted and 2 It may be composed of two diodes.
  • FIG. 2 is a schematic cross-sectional view showing a schematic structure of a MOSFET constituting the switching element 311, 312, 321 and 322 according to the first embodiment.
  • FIG. 2 illustrates an n-type MOSFET.
  • a p-type semiconductor substrate 600 is used.
  • a source electrode S, a drain electrode D, and a gate electrode G are formed on the semiconductor substrate 600.
  • High-concentration impurities are ion-implanted into the portions in contact with the source electrode S and the drain electrode D to form an n-type region 601.
  • an oxide insulating film 602 is formed between the portion where the n-type region 601 is not formed and the gate electrode G. That is, an oxide insulating film 602 is interposed between the gate electrode G and the p-type region 603 of the semiconductor substrate 600.
  • Channel 604 is an n-type channel in the example of FIG.
  • FIG. 3 is a time chart showing the timing at which the control unit 10 turns on the switching element in the power conversion device 100 according to the first embodiment.
  • the horizontal axis is time.
  • the vertical axis indicates, in order from the top, the power supply voltage Vs detected by the power supply voltage detection unit 5, the power supply current Is detected by the power supply current detection unit 6, the zero cross signal output from the zero cross detection unit 9, and This is a drive signal generated by the control unit 10 for each switching element 311, 312, 321 and 322.
  • FIG. 3 is a time chart showing the timing at which the control unit 10 turns on the switching element in the power conversion device 100 according to the first embodiment.
  • the horizontal axis is time.
  • the vertical axis indicates, in order from the top, the power supply voltage Vs detected by the power supply voltage detection unit 5, the power supply current Is detected by the power supply current detection unit 6, the zero cross signal output from the zero cross detection unit 9, and This is a drive signal generated by the control unit 10 for each switching element 311, 312, 321 and
  • the switching elements 311, 312 are current-synchronized switching elements whose on / off is controlled according to the polarity of the power supply current Is, and the switching elements 321 and 322 correspond to the polarity of the power supply voltage Vs. It shows that it is a voltage-synchronized switching element whose on / off is controlled. Further, in FIG. 3, Is and ⁇ Ith indicate a current threshold value. Although FIG. 3 shows one cycle of AC power output from the AC power source 1, the control unit 10 shall perform the same control as the control shown in FIG. 3 in other cycles.
  • the control unit 10 is a switching element of the first arm 31 that controls switching according to the power supply current Is output from the AC power supply 1 among the plurality of arms of the rectifier circuit 3.
  • the control unit 10 turns off the switching elements 311, 312, and then passes a current through the parasitic diodes 311a and 312a connected in parallel.
  • the first arm 31 may be referred to as a power supply current synchronization arm that synchronizes with the power supply current Is.
  • the control unit 10 determines the power supply polarity of the AC power supply 1 based on the zero-cross signal from the zero-cross detection unit 9 (step S1). Since the power supply polarity of the AC power supply 1 is positive, the control unit 10 generates a drive signal for turning on the switching element 322 and outputs it to the rectifier circuit 3 to turn on the switching element 322 (step S2). In the power conversion device 100, when the DC voltage Vout is higher than the power supply voltage Vs of the AC power supply 1, the power supply current Is is zero, and the power supply current Is does not flow from the AC power supply 1 to the rectifier circuit 3 (step S3).
  • the control unit 10 leaves the switching element 311 off and causes the power supply current Is to flow toward the load 50 via the parasitic diode 311a connected in parallel to the switching element 311 (step S4). At this time, in the parasitic diode 311a, a loss proportional to the square of the current, that is, the power supply current Is occurs.
  • step S5 When the power supply current Is becomes larger than the current threshold value Is (step S5), the control unit 10 generates a drive signal for turning on the switching element 311 and outputs the drive signal to the rectifier circuit 3 to turn on the switching element 311 (step). S6).
  • the control unit 10 causes the power supply current Is to flow toward the load 50 via the switching element 311. Since the control unit 10 does not pass the power supply current Is to the parasitic diode 311a in which the loss is generated in proportion to the square of the power supply current Is, the loss can be reduced.
  • the control unit 10 When the power supply current Is becomes equal to or less than the current threshold value Is (step S7), the control unit 10 generates a drive signal for turning off the switching element 311 and outputs the drive signal to the rectifier circuit 3 to turn off the switching element 311 (step S8). ).
  • the control unit 10 causes the power supply current Is to flow toward the load 50 via the parasitic diode 311a. Since the frequency of the power supply voltage Vs of the AC power supply 1 is known, the control unit 10 drives the switching element 322 to turn off in consideration of the dead time until the power supply polarity of the AC power supply 1 switches from positive to negative. A signal is generated and output to the rectifier circuit 3 to turn off the switching element 322 (step S9).
  • the control unit 10 determines the power polarity of the AC power supply 1 based on the zero-cross signal from the zero-cross detection unit 9 (step S10). Since the power supply polarity of the AC power supply 1 is negative, the control unit 10 generates a drive signal for turning on the switching element 321 and outputs the drive signal to the rectifier circuit 3 to turn on the switching element 321 (step S11). In the power converter 100, when the bus voltage Vdc is higher than the absolute value of the power supply voltage Vs of the AC power supply 1, the power supply current Is is zero, and the power supply current Is does not flow from the AC power supply 1 to the rectifier circuit 3 (step S12). ).
  • the control unit 10 leaves the switching element 312 off and causes the power supply current Is to flow toward the load 50 via the parasitic diode 312a connected in parallel to the switching element 312 (step S13). At this time, in the parasitic diode 312a, a loss proportional to the square of the current, that is, the power supply current Is occurs.
  • the control unit 10 When the power supply current Is becomes smaller than the current threshold value ⁇ Is (step S14), the control unit 10 generates a drive signal for turning on the switching element 312, outputs the drive signal to the rectifier circuit 3, and turns on the switching element 312 (step S14). Step S15).
  • the control unit 10 causes the power supply current Is to flow toward the load 50 via the switching element 312. Since the control unit 10 does not pass the power supply current Is to the parasitic diode 312a where the loss is generated in proportion to the square of the power supply current Is, the loss can be reduced.
  • the control unit 10 When the power supply current Is becomes equal to or higher than the current threshold value ⁇ Ith (step S16), the control unit 10 generates a drive signal for turning off the switching element 312 and outputs the drive signal to the rectifier circuit 3 to turn off the switching element 312 (step S16). S17).
  • the control unit 10 causes the power supply current Is to flow toward the load 50 via the parasitic diode 312a. Since the frequency of the power supply voltage Vs of the AC power supply 1 is known, the control unit 10 drives the switching element 321 to be turned off in consideration of the dead time from negative to positive when the power supply polarity of the AC power supply 1 switches from negative to positive. A signal is generated and output to the rectifier circuit 3 to turn off the switching element 321 (step S18).
  • step S19 is step S1 of the next cycle. While the power conversion device 100 is operating, the control unit 10 repeats the above operation to perform synchronous rectification.
  • FIG. 4 is a diagram showing a state of current flowing in steps S4 and S8 of FIG. 3 in the power conversion device 100 according to the first embodiment.
  • FIG. 5 is a diagram showing a state of the current flowing in step S6 of FIG. 3 in the power conversion device 100 according to the first embodiment.
  • the power conversion device 100 can reduce the loss in the rectifier circuit 3 as compared with the state of FIG. 4 by performing synchronous rectification without using the parasitic diode 311a.
  • FIG. 6 is a diagram showing a state of current flowing in steps S13 and S17 of FIG. 3 in the power conversion device 100 according to the first embodiment.
  • FIG. 7 is a diagram showing a state of the current flowing in step S15 of FIG. 3 in the power conversion device 100 according to the first embodiment.
  • the power conversion device 100 can reduce the loss in the rectifier circuit 3 as compared with the state of FIG. 6 by performing synchronous rectification without using the parasitic diode 312a.
  • the control unit 10 determines the gate-on timing of the switching element, that is, the MOSFET, based on the polarity of the power supply voltage Vs and the power supply current Is.
  • the control unit 10 turns on the gate of the switching element, that is, the MOSFET, so that the MOSFET in the current flow section Synchronous rectification is possible through.
  • the switching element 311 and the parasitic diode 311a are used will be described, but the same applies to the case where the switching element 312 and the parasitic diode 312a are used.
  • the control unit 10 slowly starts current flow at the rising edge of the power supply current Is by utilizing the current rising characteristic of the parasitic diode 311a, and the voltage across the switching element 311 is the parasitic diode 311a.
  • the switching element 311 is turned on after the voltage across the above reaches Vf.
  • the smaller the drain-source voltage of a MOSFET the smaller the switching loss.
  • the control unit 10 passes the voltage between the drain and source of the switching element 311 through the parasitic diode 311a to transfer the voltage between the drain and source of the switching element 311 across the parasitic diode 311a. Reduce to voltage Vf. In this way, the control unit 10 reduces the switching loss in the switching element 311 by passing it through the parasitic diode 311a to reduce the voltage between the drain and source of the switching element 311 and then turning on the switching element 311. Can be done. Further, since the control unit 10 can reduce the voltage change in the switching element 311, the voltage ringing can be reduced.
  • FIG. 8 is a diagram showing a loss generated in the switching element of the rectifier circuit 3 of the power conversion device 100 according to the first embodiment.
  • V DS represents the drain-source voltage of the switching element
  • V DSmax represents a drain-source voltage maximum of the switching element
  • I D denotes the drain current of the switching element
  • I DMAX is the drain of the switching element shows the current maximum value
  • T R denotes the rise time when the switching element
  • T F denotes the fall time of the oFF of the switching element.
  • the switching loss P SW of the switching element is expressed by the following equation (1).
  • the drain current maximum value I DMAX, the drain-source voltage maximum V DSmax of the switching element, rise time when the switching element T R, and the fall time of the OFF of the switching element T By reducing one or more of F , the switching loss PSW of the switching element can be reduced.
  • the drain-source voltage maximum V DSmax of the switching element by reducing the drain-source voltage maximum V DSmax of the switching element to reduce the switching loss P SW of the switching element.
  • a voltage obtained by subtracting the voltage across the reactor 2 and the bus voltage Vdc from the power supply voltage Vs is applied to the switching element of the rectifier circuit 3 between the drain and the source. It is at stake as the voltage V DS.
  • the drain-source voltage VDS is passed through the parasitic diode to reduce the voltage across the parasitic diode to Vf.
  • Control unit 10 when the power supply voltage Vs- bus voltage Vdc >> drain-source voltage V DS across the voltage Vf> switching element 311 of the parasitic diode 311a, turn on the switching element 311 after having flowed through the parasitic diode 311a To do.
  • the control unit 10 turns on the switching element 311 without flow through the parasitic diode 311a when the voltage across Vf> supply voltage Vs- bus voltage Vdc> drain-source voltage V DS of the switching element 311 of the parasitic diode 311a You may.
  • the control unit 10 is based on the result of comparing the power supply current Is and the current thresholds Is, ⁇ Ith with respect to the timing of turning on the switching elements 311, 312 after passing through the parasitic diodes 311a and 312a.
  • the input side of the rectifying circuit 3 is related to the relationship between the power supply voltage Vs, the reactance of the reactor 2, the capacitance of the smoothing capacitor 4, the zero cross value of the power supply voltage Vs, the load current Iout, and the DC voltage Vout.
  • the magnitude relationship between the potential and the potential on the output side of the rectifying circuit 3 can be analytically obtained and set.
  • the current thresholds Is and ⁇ Ith may be set based on the detection result acquired from each detection unit by the control unit 10, that is, the physical quantity, or the designer of the power conversion device 100 or the like connects to the power conversion device 100. It may be set by simulation or actual measurement in consideration of the load 50 and the like.
  • the designer of the power conversion device 100 creates, for example, a table showing the relationship between each physical quantity and the current threshold values Is and ⁇ Ith, and causes the control unit 10 to hold the table. By holding a table showing the relationship between each physical quantity and the current thresholds Is and ⁇ Ith in advance, the control unit 10 can reduce the processing load as compared with the case of calculating the current thresholds Is and ⁇ Ith. ..
  • FIG. 9 is a flowchart showing an operation in which the control unit 10 of the power conversion device 100 according to the first embodiment turns on and off the switching element.
  • the control unit 10 determines whether or not to execute the synchronous rectification control (step S102).
  • the control unit 10 controls the on / off of the switching elements 321 and 322 of the rectifier circuit 3 according to the zero cross signal from the zero cross detection unit 9 (step S103).
  • the control unit 10 compares the power supply current Is detected by the power supply current detection unit 6 with the current threshold value Is (step S104). When the power supply current Is is larger than the current threshold value Is (step S104: Yes), the control unit 10 turns on the switching element 311 (step S105). When the power supply current Is is equal to or less than the current threshold value Is (step S104: No), the control unit 10 turns off the switching element 311 (step S106).
  • the control unit 10 compares the power supply current Is with the current threshold value-Ith (step S107). When the power supply current Is is smaller than the current threshold value ⁇ Is (step S107: Yes), the control unit 10 turns on the switching element 312 (step S108). When the power supply current Is is equal to or higher than the current threshold value ⁇ Is (step S107: No), the control unit 10 turns off the switching element 312 (step S109). The control unit 10 returns to step S103 and repeats the above operation. When the synchronous rectification control is not performed (step S102: No), the control unit 10 turns off all switching elements 311, 312, 321 and 322 (step S110). The control unit 10 returns to step S102 and repeats the above operation.
  • the control unit 10 turns on the switching element 311 when the current value of the power supply current Is is larger than the current threshold value Is, and the switching element 312 when the current value of the power supply current Is is smaller than the current threshold value ⁇ Ith.
  • the current threshold value Is may be referred to as a first current threshold value
  • the current threshold value ⁇ Ith may be referred to as a second current threshold value.
  • FIG. 10 is a diagram showing an example of a hardware configuration that realizes the control unit 10 included in the power conversion device 100 according to the first embodiment.
  • the control unit 10 is realized by the processor 201 and the memory 202.
  • the processor 201 is a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, DSP (Digital Signal Processor)), or system LSI (Large Scale Integration).
  • the memory 202 is a non-volatile or volatile memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory).
  • RAM Random Access Memory
  • ROM Read Only Memory
  • flash memory EPROM (Erasable Programmable Read Only Memory), and EPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory).
  • a semiconductor memory can be exemplified.
  • the memory 202 is not limited to these, and may be a magnetic disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc).
  • the control unit 10 when performing synchronous rectification control, the control unit 10 is connected in parallel to the switching element 311 before turning on the switching element 311 of the rectifier circuit 3.
  • the parasitic diode 311a is passed through, and the parasitic diode 312a connected in parallel to the switching element 312 is passed before the switching element 312 of the rectifier circuit 3 is turned on.
  • the control unit 10 controls the flow to the switching elements 311, 312 and the parasitic diodes 311a and 312a based on the comparison result between the power supply current Is and the current thresholds Is and ⁇ Ith.
  • the control unit 10 can suppress a sudden change in the voltage between the drain sources in the switching elements 311, 312 which are MOSFETs, and can suppress ringing when it is on or off.
  • control unit 10 can contribute to noise reduction and loss reduction of the switching elements 311, 312. Further, the control unit 10 can suppress a spike current in which the energy charged in the smoothing capacitor 4 on the DC power supply side flows back to the AC power supply 1 side via the wiring, and destroys the AC power supply 1, the smoothing capacitor 4, and the like. It can be suppressed. By turning the switching elements 311, 312 on and off at the timing shown in FIG. 3, the control unit 10 can reduce the loss during switching of the switching elements 311, 312, and can improve the efficiency of the power conversion device 100.
  • Embodiment 2 In the first embodiment, when the control unit 10 passes a current through a parasitic diode connected in parallel to the switching element and then passes a current through the switching element, the current flow path uses the current thresholds Is and ⁇ Ith. Was changing. In the second embodiment, the control unit 10 changes the current flow path by using the phase of the power supply voltage Vs of the AC power supply 1.
  • the configuration of the power conversion device 100 is the same as that of the first embodiment shown in FIG.
  • the control unit 10 determines whether the switching elements 311, 312 pass the current or the parasitic diodes 311a, 312a pass the current. It is controlled by using the phase ⁇ v of the power supply voltage Vs. Specifically, in FIG. 3, from the first zero cross in which the polarity of the power supply voltage Vs is switched from negative to positive, the phase of the timing of step S5 is set to the first phase ⁇ 1, and the timing of step S7 is set to the second phase. Let it be ⁇ 2.
  • the phase of the timing of step S14 is set to the third phase ⁇ 3, and the timing of step S16 is set to the fourth phase ⁇ 4.
  • the control unit 10 turns on the switching element 311 when the phase ⁇ v of the power supply voltage Vs is the first phase ⁇ 1, and turns off the switching element 311 when the phase of the power supply voltage Vs is the second phase ⁇ 2.
  • the control unit 10 turns on the switching element 312 when the phase ⁇ v of the power supply voltage Vs is the third phase ⁇ 3, and turns off the switching element 312 when the phase of the power supply voltage Vs is the fourth phase ⁇ 4.
  • the third phase ⁇ 3 and the fourth phase ⁇ 4 may start from the first zero cross instead of the second zero cross.
  • the AC power supply 1 charges the smoothing capacitor 4. This is performed based on the magnitude relationship between the voltage Vcharge and the discharge voltage Vdischarge consumed from the smoothing capacitor 4. Under the condition of Vcharge ⁇ Vdischarge, no current flows from the AC power supply 1 to the smoothing capacitor 4, so that the switching element remains off. Under the condition of Vcharge> Vdischarge, a current flows from the AC power supply 1 to the smoothing capacitor 4, so the switching element is turned on.
  • the method for setting the first phase ⁇ 1, the second phase ⁇ 2, the third phase ⁇ 3, and the fourth phase ⁇ 4 is the same as the method for setting the current thresholds Is and ⁇ Ith in the first embodiment. You may.
  • the detection results acquired by the control unit 10 from each detection unit may be set based on a physical quantity, or may be set by a designer of the power conversion device 100 or the like by simulation or actual measurement in consideration of a load 50 or the like connected to the power conversion device 100.
  • FIG. 11 is a flowchart showing an operation in which the control unit 10 of the power conversion device 100 according to the second embodiment turns on and off the switching element.
  • the control unit 10 determines whether or not to execute the synchronous rectification control (step S202).
  • the control unit 10 controls the on / off of the switching elements 321 and 322 of the rectifier circuit 3 according to the zero cross signal from the zero cross detection unit 9 (step S203).
  • the control unit 10 compares the phase ⁇ v of the power supply voltage Vs detected by the power supply voltage detection unit 5 with the first phase ⁇ 1 and the second phase ⁇ 2 (step S204). When the phase ⁇ v of the power supply voltage Vs is larger than the first phase ⁇ 1 and smaller than the second phase ⁇ 2 (step S204: Yes), the control unit 10 turns on the switching element 311 (step S205). When the phase ⁇ v of the power supply voltage Vs is equal to or less than the first phase ⁇ 1 or equal to or greater than the second phase ⁇ 2 (step S204: No), the control unit 10 turns off the switching element 311 (step S206).
  • the control unit 10 compares the phase ⁇ v of the power supply voltage Vs with the third phase ⁇ 3 and the fourth phase ⁇ 4 (step S207). When the phase ⁇ v of the power supply voltage Vs is larger than the third phase ⁇ 3 and smaller than the fourth phase ⁇ 4 (step S207: Yes), the control unit 10 turns on the switching element 312 (step S208). When the phase ⁇ v of the power supply voltage Vs is the third phase ⁇ 3 or less or the fourth phase ⁇ 4 or more (step S207: No), the control unit 10 turns off the switching element 312 (step S209). The control unit 10 returns to step S203 and repeats the above operation. When the synchronous rectification control is not performed (step S202: No), the control unit 10 turns off all switching elements 311, 312, 321 and 322 (step S210). The control unit 10 returns to step S202 and repeats the above operation.
  • the control unit 10 passes.
  • the switching element 311 is turned on, and when the second phase ⁇ 2 elapses from the first zero cross, the switching element 311 is turned off.
  • the control unit 10 is a switching element when the third phase ⁇ 3 defined by the power supply voltage Vs elapses from the second zero cross in which the polarity of the power supply voltage Vs output from the AC power supply 1 is switched from positive to negative.
  • the 312 is turned on, and when the fourth phase ⁇ 4 elapses from the second zero cross, the switching element 312 is turned off.
  • the control unit 10 when performing synchronous rectification control, the control unit 10 is connected in parallel to the switching element 311 before turning on the switching element 311 of the rectifier circuit 3.
  • the parasitic diode 311a is passed through, and the parasitic diode 312a connected in parallel to the switching element 312 is passed before the switching element 312 of the rectifier circuit 3 is turned on.
  • the control unit 10 is based on the comparison result between the phase ⁇ v of the power supply voltage Vs and the first phase ⁇ 1, the second phase ⁇ 2, the third phase ⁇ 3, and the fourth phase ⁇ 4. , Controls the flow to the switching elements 311, 312 and the parasitic diodes 311a, 312a. Even in this case, the control unit 10 can obtain the same effect as in the first embodiment.
  • Embodiment 3 In the first embodiment, when the control unit 10 passes a current through a parasitic diode connected in parallel to the switching element and then passes a current through the switching element, the current flow path uses the current thresholds Is and ⁇ Ith. Was changing. In the third embodiment, the control unit 10 changes the current flow path by using the differential value of the power supply current Is of the AC power supply 1.
  • the configuration of the power conversion device 100 is the same as that of the first embodiment shown in FIG.
  • the control unit 10 determines whether the switching elements 311, 312 pass the current or the parasitic diodes 311a, 312a pass the current. It is controlled by using the differential value of the power supply current Is.
  • the control unit 10 turns on the switching element 311 when the power supply voltage Vs of the AC power supply 1 has a positive polarity and the differential value of the power supply current Is of the AC power supply 1 is larger than the change amount threshold value ⁇ TH.
  • the change amount threshold value ⁇ TH indicates the timing of step S5 in FIG.
  • the control unit 10 turns on the switching element 312 when the power supply voltage Vs of the AC power supply 1 has a negative polarity and the differential value of the power supply current Is of the AC power supply 1 is smaller than the change amount threshold value ⁇ TH.
  • the change amount threshold value ⁇ TH indicates the timing of step S14 in FIG.
  • the method of setting the change amount thresholds ⁇ TH and ⁇ TH can be obtained according to the load power supplied to the load 50. That is, the change amount thresholds ⁇ TH and ⁇ TH can be set according to the operating state of the load 50.
  • the method of setting the change amount thresholds ⁇ TH and ⁇ TH may be the same as the method of setting the current thresholds Is and ⁇ Ith in the first embodiment.
  • the change amount thresholds ⁇ TH and ⁇ TH may be set based on the detection result acquired from each detection unit by the control unit 10, that is, the physical quantity, as in the case of the first embodiment, or the design of the power conversion device 100 may be set. A person or the like may set it by simulation or actual measurement in consideration of a load 50 or the like connected to the power conversion device 100.
  • FIG. 12 is a flowchart showing an operation in which the control unit 10 of the power conversion device 100 according to the third embodiment turns on and off the switching element.
  • the control unit 10 determines whether or not to execute the synchronous rectification control (step S302).
  • the control unit 10 controls on / off of the switching elements 321 and 322 of the rectifier circuit 3 according to the zero cross signal from the zero cross detection unit 9 (step S303).
  • the control unit 10 compares the differential value of the power supply current Is detected by the power supply current detection unit 6 with the change amount threshold value ⁇ TH (step S304). When the differential value of the power supply current Is is larger than the change amount threshold value ⁇ TH (step S304: Yes), the control unit 10 turns on the switching element 311 (step S305). When the differential value of the power supply current Is is equal to or less than the change amount threshold value ⁇ TH (step S304: No), the control unit 10 turns off the switching element 311 (step S306).
  • the control unit 10 compares the differential value of the power supply current Is with the change amount threshold value ⁇ TH (step S307). When the differential value of the power supply current Is is smaller than the change amount threshold value ⁇ TH (step S307: Yes), the control unit 10 turns on the switching element 312 (step S308). When the differential value of the power supply current Is is equal to or greater than the change amount threshold value ⁇ TH (step S307: No), the control unit 10 turns off the switching element 312 (step S309). The control unit 10 returns to step S303 and repeats the above operation. When the synchronous rectification control is not performed (step S302: No), the control unit 10 turns off all switching elements 311, 312, 321 and 322 (step S310). The control unit 10 returns to step S302 and repeats the above operation.
  • the control unit 10 determines the switching element 311. Turn on. Further, the control unit 10 turns on the switching element 312 when the polarity of the power supply voltage Vs is negative and the differential value of the current value of the power supply current Is is smaller than the change amount threshold value ⁇ TH.
  • the change amount threshold ⁇ TH may be referred to as a first change amount threshold, and the change amount threshold ⁇ TH may be referred to as a second change amount threshold.
  • the control unit 10 when performing synchronous rectification control, the control unit 10 is connected in parallel to the switching element 311 before turning on the switching element 311 of the rectifier circuit 3.
  • the parasitic diode 311a is passed through, and the parasitic diode 312a connected in parallel to the switching element 312 is passed before the switching element 312 of the rectifier circuit 3 is turned on.
  • the control unit 10 controls the flow to the switching elements 311, 312 and the parasitic diodes 311a and 312a based on the comparison result between the differential value of the power supply current Is and the change amount thresholds ⁇ TH and ⁇ TH. To do. Even in this case, the control unit 10 can obtain the same effect as in the first embodiment.
  • the configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)
PCT/JP2019/034300 2019-08-30 2019-08-30 電力変換装置 WO2021038882A1 (ja)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002345250A (ja) * 2001-05-11 2002-11-29 Tdk Corp 整流回路
JP2011151984A (ja) * 2010-01-22 2011-08-04 Mitsubishi Electric Corp 直流電源装置、これを備えた冷凍サイクル装置、並びに、これを搭載した空気調和機及び冷蔵庫
JP2018068028A (ja) * 2016-10-19 2018-04-26 日立ジョンソンコントロールズ空調株式会社 電力変換装置および空気調和機

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002345250A (ja) * 2001-05-11 2002-11-29 Tdk Corp 整流回路
JP2011151984A (ja) * 2010-01-22 2011-08-04 Mitsubishi Electric Corp 直流電源装置、これを備えた冷凍サイクル装置、並びに、これを搭載した空気調和機及び冷蔵庫
JP2018068028A (ja) * 2016-10-19 2018-04-26 日立ジョンソンコントロールズ空調株式会社 電力変換装置および空気調和機

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