JP2013005644A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion device capable of achieving loss reduction and downsizing in a configuration in which an AC voltage is converted to a DC voltage and a level of the DC voltage can be adjusted.SOLUTION: In power conversion device 101, a step-up/down circuit 52 converts and outputs a voltage rectified by a rectification circuit 51, and comprises: a step-down switching element TR11 which switches a voltage rectified by a rectification circuit 51; and a step-up switching element TR12 which switches the voltage rectified by the rectification circuit 51. A control unit 14 generates a DC voltage output from the step-up/down circuit 52 and a control voltage indicating an error of an input current flowing from the rectification circuit 51 to the step-up/down circuit 52, switches the step-down switching element TR11 on the basis of the comparison result between the control voltage and a step-down triangular wave, and switches the step-up switching element TR12 on the basis of the comparison result between the control voltage and a step-up triangular wave.

Description

  The present invention relates to a power conversion device, and more particularly to a power conversion device that converts an AC voltage into a DC voltage.

  2. Description of the Related Art Power converters for charging driving main batteries such as electric vehicles (EV) and plug-in hybrid vehicles (HV) using ordinary household AC power have been developed.

  One of the features of an electric vehicle and a plug-in hybrid car is that an in-vehicle battery as a main battery can be charged using an external power source such as a household outlet. In order to charge a vehicle-mounted battery using an AC outlet of 100 V AC or 200 V AC, an AC / DC converter for converting AC voltage (AC) into DC voltage (DC) for the battery is required.

  As an example of the AC / DC converter, for example, Patent Document 1 (Japanese Patent Laid-Open No. 10-304670) discloses the following configuration. That is, in the step-up AC / DC converter shown in FIG. 4b of Patent Document 1, the magnetic energy is accumulated in the reactor by short-circuiting the power source with the semiconductor switch and the inductor, and the magnetic energy accumulated when the switch is turned off is used as the current energy. Convert and supply current to the load side.

  In this AC / DC converter, the output voltage is larger than the peak value of the AC voltage that is the input voltage. For example, when the amplitude of the AC voltage is 200V, the level of the output DC voltage is 280V or more. For this reason, depending on the magnitude of the input voltage, an excessive voltage may be applied to the load.

  In order to solve such a problem, in the buck-boost type AC / DC converter shown in FIG. 4c of Patent Document 1, the output of the rectifier circuit is short-circuited by a switch and a reactor, and a capacitor is connected to both ends of the reactor. And commutation diodes are connected in series. The capacitor is charged via the commutation diode by the induced electromotive force generated in the reactor when the switch is turned off.

  In this AC / DC converter, by changing the duty ratio of the signal for controlling the switch, both the step-down and step-up of the output voltage are possible, and the output voltage can be set to an arbitrary level.

Japanese Patent Laid-Open No. 10-304670

  However, in the step-up / step-down AC / DC converter shown in FIG. 4c of Patent Document 1, when the switch is in the OFF state, a voltage corresponding to the sum of the input voltage and the output voltage is applied to the switch. For this reason, it is necessary to increase the breakdown voltage of the switch as compared with the step-up AC / DC converter shown in FIG. 4B of Patent Document 1, and the size of the switch is increased. Similarly, it is necessary to increase the withstand voltage of the reactor, which increases the size. Furthermore, compared with the step-up AC / DC converter shown in FIG. 4b of Patent Document 1, since the current flowing through the switch and the reactor is increased, the loss is increased and the efficiency is lowered.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to reduce loss and reduce size in a configuration in which an AC voltage is converted into a DC voltage and the level of the DC voltage can be adjusted. It is providing the power converter device which can be performed.

  In order to solve the above problems, a power conversion device according to an aspect of the present invention is a power conversion device for converting an AC voltage into a DC voltage, and a rectifier circuit for rectifying the AC voltage; A voltage that is rectified by the rectifier circuit is converted into a DC voltage and output, and the voltage level of the DC voltage is adjustable, and the voltage booster / step-down circuit switches the voltage rectified by the rectifier circuit. A step-down switching element for switching, and a step-up switching element for switching the voltage rectified by the rectifying circuit, and the power converter further includes the DC voltage output from the step-up / down circuit, and A control voltage indicating an error of an input current flowing from the rectifier circuit to the step-up / down circuit is generated, and the control voltage is calculated based on a comparison result between the control voltage and a step-down triangular wave. The pressure switch element switching, a control unit for switching the boost switch element based on a comparison result of the control voltage and the step-up triangular wave.

  With such a configuration, compared to the step-up / step-down AC / DC converter shown in FIG. 4c of Patent Document 1, it is possible to reduce the voltage applied to electrical components such as transistors in the step-up / step-down circuit. The current flowing through the switch and the reactor can be reduced. Therefore, it is possible to improve the efficiency by reducing the loss in the electric parts such as the switch and the reactor, and to reduce the size of the electric parts such as the reactor.

  Preferably, the control unit determines whether to switch the step-down switch element based on a comparison result between the control voltage and the step-down triangular wave, and compares the control voltage with the step-up triangular wave. Based on the result, it is determined whether or not to switch the boosting switch element.

  As described above, the step-up / step-down circuit can be appropriately operated by switching the step-up operation and the step-down operation on and off according to the control voltage.

  Preferably, the maximum value and the minimum value of the level of the step-down triangular wave are larger than the maximum value and the minimum value of the level of the step-up triangular wave, respectively.

  With such a configuration, the levels of the step-down triangular wave and the step-up triangular wave can be set appropriately, and the operation of the step-up / down circuit can be stabilized.

  More preferably, the level range of the step-down triangular wave and the level range of the step-up triangular wave partially overlap, and the phase and period of the step-down triangular wave and the step-up triangular wave are the same.

  With such a configuration, the level, phase and period of the step-down triangular wave and the step-up triangular wave can be set appropriately, and the operation of the step-up / step-down circuit can be further stabilized.

  More preferably, the minimum value of the step-down triangular wave level is equal to the maximum value of the step-up triangular wave level.

  As described above, the configuration in which the minimum value of the step-down triangular wave is matched with the maximum value of the step-up triangular wave can increase the degree of freedom in setting the shape and phase of the step-up triangular wave and the step-down triangular wave.

  More preferably, the waveform of the step-down triangular wave and the step-up triangular wave are waveforms in which the level gradually increases from the minimum value to the maximum value and gradually decreases to the minimum value when the maximum value is reached.

  By adopting such a triangular wave, even if the phase of each triangular wave fluctuates due to variations in each circuit, it is possible to prevent a short circuit from occurring in the buck-boost circuit. Further, even if the level of each triangular wave varies due to variations in each circuit, it is possible to prevent the operation of the step-up / down circuit from becoming unstable.

  More preferably, the waveform of the step-down triangular wave and the step-up triangular wave are waveforms in which the level gradually decreases from the maximum value and switches to the maximum value when reaching the minimum value.

  By adopting such a triangular wave, it is possible to prevent the operation of the step-up / step-down circuit from becoming unstable even if the level of each triangular wave varies due to variations in each circuit.

  More preferably, the waveform of the step-down triangular wave and the step-up triangular wave are waveforms that gradually increase from the minimum value and switch to the minimum value when the maximum value is reached.

  By adopting such a triangular wave, it is possible to prevent the operation of the step-up / step-down circuit from becoming unstable even if the level of each triangular wave varies due to variations in each circuit.

  Preferably, the power conversion device further includes a power transmission insulating circuit for transmitting the DC voltage received from the step-up / down circuit to the load while insulating the input side and the output side.

  With such a configuration, compared to the step-up / step-down AC / DC converter shown in FIG. 4c of Patent Document 1, it is possible to reduce the voltage applied to electrical components such as transistors in the step-up / step-down circuit. The current flowing through the switch and the reactor can be reduced. Therefore, it is possible to improve the efficiency by reducing the loss in the electric parts such as the switch and the reactor, and to reduce the size of the electric parts such as the reactor.

  According to the present invention, it is possible to reduce loss and reduce the size in a configuration in which an AC voltage is converted into a DC voltage and the level of the DC voltage can be adjusted.

It is a figure which shows the structure of the power converter device which concerns on embodiment of this invention. It is a figure which shows the structure of the control part in the power converter device which concerns on embodiment of this invention. It is a figure which shows the operation | movement which the control part in the power converter device which concerns on embodiment of this invention produces | generates a control signal. It is a figure which shows an example of the change of each voltage in the control part which concerns on embodiment of this invention. It is a figure which shows an example of the change of each voltage in the control part which concerns on embodiment of this invention. It is a figure which shows an example of the change of each voltage in the control part which concerns on embodiment of this invention. It is a figure which shows the other example of the triangular wave and control signal in the power converter device which concerns on embodiment of this invention. It is a figure which shows the other example of the triangular wave and control signal in the power converter device which concerns on embodiment of this invention. It is a figure which shows the other example of the triangular wave and control signal in the power converter device which concerns on embodiment of this invention. It is a figure which shows the other example of the triangular wave and control signal in the power converter device which concerns on embodiment of this invention. It is a figure which shows the other example of the triangular wave and control signal in the power converter device which concerns on embodiment of this invention. It is a figure which shows the switching operation | movement by the insulated circuit for electric power transmission which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Configuration and basic operation]
FIG. 1 is a diagram showing a configuration of a power conversion device according to an embodiment of the present invention.

  With reference to FIG. 1, the power conversion device 101 includes a rectifier circuit 51, a step-up / down circuit 52, a power transmission insulating circuit 53, and a control unit 14. The step-up / step-down circuit 52 includes capacitors C11 and C12, transistors TR11 and TR12, an inductor L11, and diodes D11 and D12. The power transmission insulating circuit 53 includes capacitors C0, C1, C2, an input switch unit 21, and an output switch unit 22. The input switch unit 21 includes transistors TR21 and TR22. The output switch unit 22 includes transistors TR23 and TR24. Transistors TR11, TR12, TR21, TR22, TR23, and TR24 are, for example, IGBTs (Insulated Gate Bipolar Transistors). In the power conversion device 101, other types of switch elements may be used instead of these transistors.

  The power conversion device 101 converts AC power supplied from the AC power source 201 into DC power and supplies the DC power to the load 202. The load 202 is a main battery for driving such as EV and plug-in HV, for example.

  In the step-up / step-down circuit 52, the transistor TR11 includes a gate that receives the control signal G11 from the control unit 14, a collector connected to the rectifier circuit 51, an emitter connected to the cathode of the diode D11 and the first end of the inductor L11. Have Transistor TR12 has a gate receiving control signal G12 from control unit 14, a collector connected to the second end of inductor L11 and the anode of diode D12, a rectifier circuit 51, an anode of diode D11, and a second end of capacitor C11. Connected to the emitter. Capacitor C12 has a first end connected to the collector of transistor TR11, and a second end connected to the anode of diode D11. The cathode of the diode D12 and the first end of the capacitor C11 are connected.

  In the power transmission insulating circuit 53, the transistor TR21 includes a gate that receives the control signal G1 from the control unit 14, an emitter connected to the second end of the capacitor C11 of the step-up / down circuit 52 and the anode of the diode D5, and a diode D5. And a collector connected to the first end of the capacitor C1. Transistor TR22 includes a gate for receiving control signal G2 from control unit 14, a collector connected to the first end of capacitor C11 of buck-boost circuit 52 and the cathode of diode D6, the anode of diode D6 and the second of capacitor C1. And an emitter connected to the end. Transistor TR23 is connected to the gate receiving control signal G3 from control unit 14, the collector connected to the cathode of diode D7 and the first end of capacitor C2, the anode of diode D7 and the first end of capacitor C1. And an emitter. Transistor TR24 is connected to the gate receiving control signal G4 from control unit 14, the collector connected to the cathode of diode D8 and the second end of capacitor C1, the anode of diode D8 and the second end of capacitor C2. And an emitter.

  The rectifier circuit 51 includes, for example, a diode bridge, and full-wave rectifies the AC voltage supplied from the AC power supply 201 and outputs it to the step-up / down circuit 52.

  The step-up / down circuit 52 converts the voltage rectified by the rectifier circuit 51 into a DC voltage. The step-up / step-down circuit 52 can adjust the level of the DC voltage by performing a step-up operation and a step-down operation.

  In the step-up / step-down circuit 52, a step-down circuit is configured by the transistor TR11 that is a step-down switching element, an inductor L11, a diode D11, and a capacitor C11. Is configured. In addition, the ripple of the input current to the buck-boost circuit 52 is suppressed by the capacitor C12.

  More specifically, in the step-up / step-down circuit 52, the transistor TR11 switches the voltage rectified by the rectifier circuit 51, for example, when the transistor TR12 is off. The inductor L11 increases the current and stores energy when the transistor TR11 is turned on. When the transistor TR11 is turned off, the energy stored in the inductor L11 is released to the capacitor C11 through the diode D12, and the capacitor C11 is charged.

  The transistor TR12 switches the voltage rectified by the rectifier circuit 51, for example, when the transistor TR11 is on. The inductor L11 increases the current and stores energy when the transistor TR12 is turned on. When the transistor TR12 is turned off, the energy stored in the inductor L11 is released to the capacitor C11 through the diode D12, and the capacitor C11 is charged.

  Control unit 14 controls switching of transistors TR11 and TR12 by outputting control signals G11 and G12 to transistors TR11 and TR12, respectively. Thereby, the step-up / step-down circuit 52 converts the voltage received from the diode D1 into a DC voltage and boosts or steps down the voltage.

Here, in the step-down operation of the step-up / step-down circuit 52, when the input voltage of the step-up / down step circuit 52 is Vin, the output voltage is Vout, and the duty ratio of the transistor TR11 is D, the output voltage Vout is expressed as follows. .
Vout = D × Vin

In the boosting operation of the step-up / step-down circuit 52, when the input voltage of the step-up / down circuit 52 is Vin, the output voltage is Vout, and the duty ratio of the transistor TR12 is D, the output voltage Vout is expressed as follows.
Vout = {1 / (1-D)} × Vin

  As can be seen from these equations, the step-up / step-down circuit 52 can obtain either an output voltage higher or lower than the input voltage depending on the setting of the duty ratio. That is, both Vin <Vout and Vin> Vout can be realized.

  The step-up / step-down circuit 52 also has a function as a power factor correction circuit. That is, the transistors TR11 and TR12 are controlled by the control unit 14 so that the phase of the input voltage of the step-up / step-down circuit 52 and the phase of the input current are matched.

  The power transmission insulating circuit 53 transmits the power received from the step-up / down circuit 52 while insulating between the input side and the output side.

  More specifically, the input switch unit 21 receives the power boosted or stepped down in the step-up / down circuit 52, that is, the power stored in the capacitors C11 and C0, at the emitter of the transistor TR21 and the collector of the transistor TR22, and supplies the same to the capacitor C1. To do. The output switch unit 22 supplies the power stored in the capacitor C1 to the capacitor C2. The electric power stored in the capacitor C2 is discharged and output to the load 202.

  The control unit 14 outputs control signals G1 to G4 to the transistors TR21 to TR24, respectively, thereby switching the transistors TR21 to TR24 on and off, respectively. The power transmission insulating circuit 53 transmits the power received from the step-up / down circuit 52 to the load 202 while insulating the step-up / down circuit 52 and the load 202 by switch control of the control unit 14.

  Further, the control unit 14 generates a control voltage indicating a DC voltage output from the step-up / down circuit 52 and an error of an input current flowing from the rectifier circuit 51 to the step-up / down circuit 52, and compares the control voltage with the step-down triangular wave. The transistor TR11 is switched based on the result, and the transistor TR12 is switched based on the comparison result between the control voltage and the boosting triangular wave.

  More specifically, the control unit 14 determines whether to switch the transistor TR11 based on the comparison result between the control voltage and the step-down triangular wave, and based on the comparison result between the control voltage and the step-up triangular wave, It is determined whether to switch the transistor TR12.

  For example, when the input voltage Vin <the output voltage Vout, the transistor TR11 is turned on and the transistor TR12 is PWM-controlled. On the other hand, when the input voltage Vin> the output voltage Vout, the transistor TR11 is PWM-controlled and the transistor TR12 is turned off.

  FIG. 2 is a diagram showing a configuration of a control unit in the power conversion device according to the embodiment of the present invention.

  Referring to FIG. 2, power conversion device 101 further includes a triangular wave oscillation circuit 15 and a resistor R11. The control unit 14 includes a differential amplifier 31, a multiplier 32, an adder 33, a differential amplifier 34, comparators 35 and 36, buffers 37 and 38, and resistors R12 and R13.

  Capacitor C12 has a first end connected to the collector of transistor TR11, and a second end. The resistor R11 is connected between the anode of the diode D11 and the second end of the capacitor C12, and is provided to detect the input current Iin of the step-up / down circuit 52.

  The triangular wave oscillation circuit 15 generates a step-down triangular wave having a minimum level of 2.5 V and a maximum level of 4 V, for example, and outputs it to the non-inverting input terminal of the comparator 35. Further, the triangular wave oscillation circuit 15 generates a boosting triangular wave having a minimum level of 1V and a maximum level of 2.5V, for example, and outputs it to the non-inverting input terminal of the comparator 36.

  The voltage dividing circuit constituted by the resistor R12 and the resistor R13 divides the output voltage Vout of the step-up / down circuit 52 and outputs it to the inverting input terminal of the differential amplifier 31.

  The differential amplifier 31 functions as an error amplifier, amplifies the difference between the divided voltage received at the inverting input terminal and the output reference voltage Vref received at the non-inverting input terminal, and outputs a differential amplified voltage ERV.

  The multiplier 32 multiplies the input voltage Vin of the step-up / step-down circuit 52 and the differential amplification voltage ERV, and outputs a voltage MOUT indicating the multiplication result to the adder 33.

  The adder 33 adds the voltage at the resistor R11 indicating the input current Iin of the step-up / step-down circuit 52 and the voltage MOUT, and outputs a voltage indicating the addition result to the inverting input terminal of the differential amplifier 34.

  The differential amplifier 34 functions as an error amplifier, amplifies the difference between the voltage received from the adder 33 at the inverting input terminal and the current reference voltage received at the non-inverting input terminal, and outputs a differential amplified voltage ERI.

  The comparator 35 compares the differential amplification voltage ERI and the step-down triangular wave, and outputs a control signal G11 indicating the comparison result to the gate of the transistor TR11 via the buffer 37.

  The comparator 36 compares the differential amplification voltage ERI and the boosting triangular wave, and outputs a control signal G12 indicating the comparison result to the gate of the transistor TR12 via the buffer 38.

  The control unit 14 generates the control signal G11 and the control signal G12 and performs PWM control on the transistors TR11 and TR12, respectively, thereby keeping the output voltage Vout of the step-up / down circuit 52 constant, Feedback control is performed to set the output current to the same phase.

[Operation]
Next, the operation of the step-up / step-down circuit according to the embodiment of the present invention will be described with reference to the drawings.

  FIG. 3 is a diagram illustrating an operation in which the control unit in the power conversion device according to the embodiment of the present invention generates a control signal.

  Referring to FIG. 3, when the level of differential amplification voltage ERI is smaller than the triangular wave for step-down, control signal G11 is at a logic high level, and when it is greater, it is at a logic low level. The transistor TR11 is turned on in response to a logic high level control signal G11, and is turned off in response to a logic low level control signal G11.

  As the control signal G11 repeats the logic high level and the logic low level, the step-down / step-down circuit 52 performs a step-down operation.

  Further, when the level of the differential amplification voltage ERI is smaller than the boosting triangular wave, the control signal G12 becomes a logic high level, and when it is larger, the control signal G12 becomes a logic low level. The transistor TR12 is turned on in response to a logic high level control signal G12, and is turned off in response to a logic low level control signal G12.

  As the control signal G12 repeats the logic high level and the logic low level, the boosting / lowering circuit 52 performs the boosting operation.

  The maximum value and minimum value of the step-down triangular wave level are larger than the maximum value and minimum value of the step-up triangular wave level, respectively. The minimum value of the step-down triangular wave level is equal to the maximum value of the step-up triangular wave level.

  As described above, the configuration in which the minimum value of the step-down triangular wave is matched with the maximum value of the step-up triangular wave can increase the degree of freedom in setting the shape and phase of the step-up triangular wave and the step-down triangular wave.

  The step-up triangular wave and the step-down triangular wave have the same phase. Thereby, in the triangular wave oscillation circuit 15, it is only necessary to provide a circuit that generates one of the boosting triangular wave and the step-down triangular wave, and a circuit that generates the other triangular wave by shifting the level of one triangular wave. The configuration of the oscillation circuit 15 can be simplified.

  FIG. 4 is a diagram illustrating an example of changes in each voltage in the control unit according to the embodiment of the present invention.

  Referring to FIG. 4, when the load current, that is, the current consumption of load 202 increases at timing ta, output voltage Vout decreases. Then, the differential amplification voltage ERV increases, the voltage MOUT increases, and the differential amplification voltage ERI decreases. As a result, the duty ratio of the step-down control signal G11 is increased and the duty ratio of the step-up control signal G12 is increased, so that the output voltage Vout is increased.

  FIG. 5 is a diagram illustrating an example of changes in each voltage in the control unit according to the embodiment of the present invention.

  Referring to FIG. 5, when the load current, that is, the current consumption of load 202 becomes small at timing tb, output voltage Vout increases. As a result, the differential amplification voltage ERV decreases, the voltage MOUT decreases, and the differential amplification voltage ERI increases. As a result, the duty ratio of the step-down control signal G11 is reduced and the duty ratio of the step-up control signal G12 is reduced, so that the output voltage Vout is lowered.

  FIG. 6 is a diagram illustrating an example of changes in each voltage in the control unit according to the embodiment of the present invention.

  Referring to FIG. 6, when power supply device 101 is turned on, the level of output voltage Vout is low, so that differential amplification voltage ERV increases, voltage MOUT increases, and differential amplification voltage ERI decreases. Become. As a result, the duty ratio of the step-down control signal G11 is increased and the duty ratio of the step-up control signal G12 is increased, so that the output voltage Vout is increased. When the output voltage Vout reaches a predetermined value, the differential amplification voltage ERV decreases and the output voltage Vout does not increase.

  FIG. 7 is a diagram illustrating another example of the triangular wave and the control signal in the power conversion device according to the embodiment of the present invention.

  Referring to FIG. 7, the waveforms of the boosting triangular wave and the stepping-down triangular wave are mountain-shaped, the phases and periods of both waves are made different, and a part of both waves is overlapped.

  When such a triangular wave is employed, there is a possibility that the transistor TR11, which is a step-down switching element, is turned off when the transistor TR12, which is a step-up switching element, is on. In this case, the reactor L11 The circuit is short-circuited with respect to the current.

  FIG. 8 is a diagram illustrating another example of the triangular wave and the control signal in the power conversion device according to the embodiment of the present invention.

  Referring to FIG. 8, the waveform of the step-up triangular wave and the step-down triangular wave are mountain-shaped, and the two waves are not overlapped.

  When such a triangular wave is adopted, when the level of the differential amplification voltage ERI is between the maximum value of the boosting triangular wave and the minimum value of the stepping-down triangular wave, the step-up / step-down circuit 52 performs either the step-up operation or the step-down operation. Is not performed, so the operation becomes unstable.

  FIG. 9 is a diagram illustrating another example of the triangular wave and the control signal in the power conversion device according to the embodiment of the present invention.

  Referring to FIG. 9, the waveform of the boosting triangular wave and the stepping-down triangular wave are mountain-shaped, and a part of both waves is overlapped.

  That is, the level range of the step-down triangular wave and the level range of the step-up triangular wave partially overlap, and the phase and period of the step-down triangular wave and the step-up triangular wave are the same. The waveform of the step-down triangular wave and the step-up triangular wave is a waveform in which the level gradually increases from the minimum value to the maximum value, and when the maximum value is reached, the level gradually decreases to the minimum value.

  By adopting such a triangular wave, even if the phase of each triangular wave fluctuates due to variations in each circuit, it is possible to prevent a short circuit from occurring in the buck-boost circuit 52 as in the triangular wave shown in FIG. Further, even if the level of each triangular wave varies due to variations in each circuit, it is possible to prevent the operation of the step-up / down circuit 52 from becoming unstable as in the triangular wave shown in FIG.

  FIG. 10 is a diagram illustrating another example of the triangular wave and the control signal in the power conversion device according to the embodiment of the present invention.

  Referring to FIG. 10, the waveform of the step-up triangular wave and the step-down triangular wave is a saw-tooth whose level gradually decreases, and a part of both waves is overlapped.

  That is, the level range of the step-down triangular wave and the level range of the step-up triangular wave partially overlap, and the phase and period of the step-down triangular wave and the step-up triangular wave are the same. The waveforms of the step-down triangular wave and the step-up triangular wave are waveforms that gradually decrease from the maximum value and switch to the maximum value when the minimum value is reached.

  By adopting such a triangular wave, even if the level of each triangular wave fluctuates due to variations in each circuit, it is possible to prevent the operation of the buck-boost circuit 52 from becoming unstable like the triangular wave shown in FIG. .

  On the other hand, if the phase of each triangular wave fluctuates due to variations in each circuit, there is a possibility that a short circuit will occur in the buck-boost circuit 52 as in the triangular wave shown in FIG. For this reason, the waveform shown in FIG. 9 is preferable.

  FIG. 11 is a diagram illustrating another example of the triangular wave and the control signal in the power conversion device according to the embodiment of the present invention.

  Referring to FIG. 11, the waveform of the boosting triangular wave and the stepping-down triangular wave is a saw-tooth whose level gradually rises, and a part of both waves is overlapped.

  That is, the level range of the step-down triangular wave and the level range of the step-up triangular wave partially overlap, and the phase and period of the step-down triangular wave and the step-up triangular wave are the same. The waveforms of the step-down triangular wave and the step-up triangular wave gradually increase from the minimum value and switch to the minimum value when the maximum value is reached.

  By adopting such a triangular wave, even if the level of each triangular wave fluctuates due to variations in each circuit, it is possible to prevent the operation of the buck-boost circuit 52 from becoming unstable like the triangular wave shown in FIG. .

  On the other hand, since the transistor TR11, which is a step-down switching element, is turned off at the timing when the transistor TR12, which is a step-up switching element, is turned off, a pure step-up operation is not performed in the step-up / down circuit 52, and a current change in the reactor L11 occurs. growing. For this reason, the triangular wave shown in FIGS. 9 and 10 is preferable.

  Next, the operation when the power transmission insulating circuit according to the embodiment of the present invention performs power transmission will be described with reference to the drawings.

  FIG. 12 is a diagram showing a switching operation by the power transmission insulating circuit according to the embodiment of the present invention.

  Referring to FIG. 12, first, in period T1, control unit 14 turns on transistor TR21, turns on transistor TR22, turns off transistor TR23, and turns off transistor TR24. Thereby, the electric charge stored in the capacitor C11 and the capacitor C0 is discharged, and the discharged electric charge is stored in the capacitor C1. Since the transistors TR23 and TR24 are turned off, insulation between the step-up / step-down circuit 52 and the load 202 is ensured.

  Next, the control unit 14 turns off the transistors TR21 to TR24 in the period T2. This provides a dead time for ensuring insulation between the input side and the output side of the power transmission insulating circuit 53. That is, it is possible to prevent a short circuit between the input side and the output side of the insulating circuit 53 for power transmission, that is, between the step-up / down circuit 52 and the load 202, via each switch in the input switch unit 21 and each switch in the output switch unit 22. Can do.

  Next, in the period T3, the control unit 14 turns off the transistor TR21, turns off the transistor TR22, turns on the transistor TR23, and turns on the transistor TR24. Thereby, the electric charge stored in the capacitor C1 is discharged, and the discharged electric charge is stored in the capacitor C2. Since the transistors TR21 and TR22 are turned off, insulation between the step-up / step-down circuit 52 and the load 202 is ensured.

  Next, the control unit 14 turns off the transistors TR21 to TR24 in the period T4. Thus, as in the period T2, a dead time is provided for ensuring insulation between the input side and the output side of the power transmission insulating circuit 53.

  Here, in the period T <b> 1 to T <b> 4, the capacitor C <b> 0 is charged with the power boosted or stepped down in the step-up / step-down circuit 52, and the power stored in the capacitor C <b> 2 is discharged and output to the load 202. In the periods T2 and T4, there is no charge movement in the capacitor C1.

  The control unit 14 repeats the period T1, the period T2, the period T3, and the period T4 in this order to isolate the input side and the output side of the power transmission insulating circuit 53 from the step-up / down circuit 52. Power, that is, DC voltage is transmitted to the load 202.

  Incidentally, in the step-up / step-down AC / DC converter shown in FIG. 4 c of Patent Document 1, it is necessary to increase the breakdown voltage of the switch as compared with the boost-type AC / DC converter shown in FIG. 4 b of Patent Document 1. This increases the size of the switch. Similarly, it is necessary to increase the withstand voltage of the reactor, which increases the size. Furthermore, compared with the step-up AC / DC converter shown in FIG. 4b of Patent Document 1, since the current flowing through the switch and the reactor is increased, the loss is increased and the efficiency is lowered.

  On the other hand, in the power conversion device according to the embodiment of the present invention, the step-up / step-down circuit 52 includes a transistor TR11 that is a step-down switch element for switching the voltage rectified by the rectifier circuit 51, and the rectifier circuit 51. And a transistor TR12 which is a step-up switching element for switching the voltage rectified by. Then, the control unit 14 generates a DC voltage output from the step-up / down circuit 52 and a control voltage indicating an error in the input current flowing from the rectifier circuit 51 to the step-up / down circuit 52, and compares the control voltage with the step-down triangular wave. The transistor TR11 is switched based on the result, and the transistor TR12 is switched based on the comparison result between the control voltage and the boosting triangular wave.

  With such a configuration, compared to the step-up / step-down AC / DC converter shown in FIG. 4c of Patent Document 1, it is possible to reduce the voltage applied to electrical components such as transistors in the step-up / step-down circuit. The current flowing through the switch and the reactor can be reduced. Therefore, it is possible to improve the efficiency by reducing the loss in the electric parts such as the switch and the reactor, and to reduce the size of the electric parts such as the reactor.

  In the power conversion device according to the embodiment of the present invention, control unit 14 determines whether or not to switch transistor TR11 based on the comparison result between the control voltage and the step-down triangular wave, and the control voltage and step-up voltage are determined. Whether or not to switch the transistor TR12 is determined based on the comparison result with the triangular wave for use.

  As described above, the step-up / step-down circuit can be appropriately operated by switching the step-up operation and the step-down operation on and off according to the control voltage.

  In the power conversion device according to the embodiment of the present invention, the maximum value and the minimum value of the step-down triangular wave level are larger than the maximum value and the minimum value of the step-up triangular wave level, respectively.

  With such a configuration, the levels of the step-down triangular wave and the step-up triangular wave can be set appropriately, and the operation of the step-up / down circuit can be stabilized.

  Further, in the power conversion device according to the embodiment of the present invention, the level range of the step-down triangular wave and the level range of the step-up triangular wave partially overlap, and the phase and period of the step-down triangular wave and the step-up triangular wave are the same. is there.

  With such a configuration, the level, phase and period of the step-down triangular wave and the step-up triangular wave can be set appropriately, and the operation of the step-up / step-down circuit can be further stabilized.

  In the power conversion device according to the embodiment of the present invention, power transmission insulating circuit 53 transmits the DC voltage received from step-up / down circuit 52 to load 202 while insulating the input side and the output side.

  With such a configuration, an AC voltage can be converted to a DC voltage without using a power transformer that occupies a large volume, and the AC power supply side and the load side can be electrically insulated.

  In addition, although the power converter device which concerns on embodiment of this invention was set as the structure provided with the insulation circuit 53 for electric power transmission, it is not limited to this. Even if the power conversion device 101 does not include the power transmission insulating circuit 53, an AC / DC converter corresponding to power factor improvement and a charger such as an EV are provided with a wide adjustment range of the input voltage and the output voltage. Is possible.

  In the power conversion device according to the embodiment of the present invention, the “inductor” includes a large component such as a reactor.

  Further, the power transmission insulating circuit 53 may be configured not to include the capacitor C0. However, the provision of the capacitor C0 provides the effect of preventing the ripple of the input current to the power transmission insulating circuit 53 and stabilizing the circuit operation.

  In addition, the power transmission insulating circuit according to the embodiment of the present invention is configured to include the capacitors C0 to C2, but is not limited to the capacitor, and is configured to include other power storage elements such as coils (inductors). May be.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 14 Control part 15 Triangular wave oscillation circuit 21 Input switch part 22 Output switch part 31 Differential amplifier 32 Multiplier 33 Adder 34 Differential amplifier 35,36 Comparator 37,38 Buffer 51 Rectifier circuit 52 Buck-boost circuit 53 Insulation for electric power transmission Circuit 101 Power converter 201 AC power supply 202 Load C0, C1, C2, C11, C12 Capacitor D11, D12 Diode TR11 Transistor (switching element for step-down)
TR12 transistor (step-up switch element)
L11 Inductor TR21, TR22, TR23, TR24 Transistors R11, R12, R13 Resistance

Claims (9)

A power converter for converting an AC voltage into a DC voltage,
A rectifier circuit for rectifying the AC voltage;
The voltage rectified by the rectifier circuit is converted into a DC voltage and output, and a step-up / down circuit capable of adjusting the level of the DC voltage is provided.
The step-up / down circuit is
A step-down switching element for switching the voltage rectified by the rectifier circuit;
A step-up switch element for switching the voltage rectified by the rectifier circuit,
The power conversion device further includes:
A control voltage indicating an error of the DC voltage output from the step-up / down circuit and an input current flowing from the rectifier circuit to the step-up / down circuit is generated, and the control voltage and the step-down triangular wave are used to generate the control voltage. A power conversion device comprising a control unit for switching a step-down switch element and switching the step-up switch element based on a comparison result between the control voltage and the step-up triangular wave.   The control unit determines whether to switch the step-down switch element based on a comparison result between the control voltage and the step-down triangular wave, and based on a comparison result between the control voltage and the step-up triangular wave The power converter according to claim 1, wherein it is determined whether to switch the boosting switch element.   3. The power converter according to claim 1, wherein a maximum value and a minimum value of the level of the step-down triangular wave are larger than a maximum value and a minimum value of the level of the step-up triangular wave, respectively.   4. The power converter according to claim 3, wherein a level range of the step-down triangular wave and a level range of the step-up triangular wave partially overlap, and the phase and period of the step-down triangular wave and the step-up triangular wave are the same. .   The power conversion device according to claim 3, wherein a minimum value of the level of the step-down triangular wave is equal to a maximum value of the level of the step-up triangular wave.   The waveform of the step-down triangular wave and the step-up triangular wave is a waveform in which the level gradually increases from the minimum value to the maximum value and gradually decreases to the minimum value when the maximum value is reached. The power converter of any one of Claim 5.   6. The waveform of the step-down triangular wave and the step-up triangular wave are waveforms in which the level gradually decreases from the maximum value and switches to the maximum value when the minimum value is reached. The power converter described.   6. The waveform of the step-down triangular wave and the step-up triangular wave are waveforms in which the level gradually increases from a minimum value and switches to the minimum value when the maximum value is reached. The power converter described. The power conversion device further includes:
7. The power transmission insulating circuit according to claim 1, further comprising a power transmission insulating circuit configured to transmit a DC voltage received from the step-up / step-down circuit to a load while insulating between the input side and the output side. Power conversion device.

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