JP2012157118A - Power conversion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion apparatus that can prevent supply of overvoltage to load while supplying power ensuing insulation between a power supply and the load.SOLUTION: A power conversion apparatus 101 includes: a voltage division circuit 11 for dividing input voltage to generate divided voltages; a voltage boost circuit 12 for converting one divided voltage to first DC voltage; a voltage boost circuit 13 for converting the other divided voltage to second DC voltage; and a power transmitting insulation circuit 14 for supplying the first and second DC voltages to load 202. The power transmitting insulation circuit 14 includes: a capacitor C5; an input switch section 21 including switch elements Q3, Q4 and supplying the first DC voltage to the capacitor C5; an input switch section 22 including switch elements Q5, Q6 and supplying the second DC voltage to the capacitor C5; and an output switch section 23 including switch elements Q7, Q8 and outputting power stored in the capacitor C5.

Description

  The present invention relates to a power conversion device, and more particularly to a power conversion device having an output voltage adjustment function.

  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.

  That is, 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.

  Patent Document 1 below discloses an AC / DC converter capable of boosting a DC voltage to be output by changing a duty ratio by switching. According to the AC / DC converter, after full-wave rectification is performed on the AC input in the booster circuit, the boosted chopper control by switching is used to turn on and off the release of energy stored in the reactor, thereby boosting the DC Get the output. Further, if the waveform of the current flowing through the reactor is controlled to be similar to the waveform of the input voltage by this on / off control, the power factor at the time of power conversion of the AC / DC converter can be improved.

  Patent Document 2 below discloses an insulating circuit for a power supply device used for an AC / DC converter. The insulation circuit for a power supply device includes a rectifier circuit that converts an AC voltage into a DC voltage, a first capacitor that reduces a pulsating current component remaining in a DC current supplied from the rectifier circuit, and the first capacitor. A first switch circuit that simultaneously opens and closes a positive side and a negative side of a supplied direct current, a second capacitor that accumulates a current supplied from the first switch circuit, and a second capacitor that is supplied from the second capacitor A second switch circuit that simultaneously opens and closes the positive side and the negative side of the direct current, and a third capacitor that holds the current supplied from the second switch circuit and discharges it to the load side. Further, the control signal φ1 constituted by a square wave set to be shorter than the time to turn off, and the control signal φ1 are turned on complementarily and the off time is set to be shorter than the off time. A gate control circuit for generating the control signal φ2 is provided. The first switch circuit is opened and closed by the control signal φ1, and the second switch circuit is opened and closed by the control signal φ2. 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.

Japanese Patent Laid-Open No. 10-304670 Japanese Patent No. 3595329

  In the AC / DC converter disclosed in Patent Document 1, an input AC voltage is boosted by a boost chopper circuit and output as a boosted DC voltage to a load. Therefore, this DC voltage has a value higher than the peak voltage of the input AC voltage, and depending on the AC voltage, an excessively large voltage may be applied to the load.

  Further, by using the power supply device isolation circuit disclosed in Patent Document 2, it is possible to transmit DC power from the power supply side to the load side while insulating the power supply side from the load side. However, even if the DC power boosted by the booster circuit is transmitted by the power supply device isolation circuit, the voltage on the power supply side and the voltage on the load side have the same voltage value, so the booster circuit outputs a voltage that is too large In other words, a voltage that is too large is applied to the load.

  The present invention has been made in view of such circumstances, and while supplying DC power to the load while ensuring insulation between the power input side and the load, it is possible to prevent an excessively high voltage from being supplied to the load. An object of the present invention is to obtain a power conversion device that can handle the above.

  A power conversion device according to a first aspect of the present invention is a power conversion device for converting input power to DC power and supplying the load to a load, and divides the input voltage to provide the first divided voltage and the first voltage. A voltage dividing circuit for generating a divided voltage of 2; a first converter for converting the first divided voltage into a first DC voltage; and converting the second divided voltage into a second DC voltage. The second converter, the first converter and the second converter, and the load, while supplying the first DC voltage and the second DC voltage to the load while insulating the load An insulating circuit, wherein the power transmission insulating circuit is connected between a power storage element having a first end and a second end, and between the first conversion unit and a first end of the power storage element. And a second switch connected between the first converter and the second end of the power storage element. And a third switch connected between the second conversion unit and the first end of the power storage device, the device including a first power supply switch for supplying the first DC voltage to the power storage device And a second input switch for supplying the second DC voltage to the power storage element, including a fourth switch element connected between the second conversion unit and the second end of the power storage element. A fifth switch element connected between the first end of the power storage element and the load, and a sixth switch element connected between the second end of the power storage element and the load And an output switch unit for supplying electric power stored in the power storage element to the load.

  According to the power conversion device of the first aspect, the voltage dividing circuit divides the input voltage, and generates the first divided voltage and the second divided voltage. The first converter converts the first divided voltage into a first DC voltage. The second converter converts the second divided voltage into a second DC voltage. In the power transmission insulating circuit, the first switch element and the second switch element are both turned on and off to supply power to the power storage element by the first DC voltage, or the first conversion unit, the power storage element, Switch between insulating. In addition, the third switch element and the fourth switch element are switched on or off to switch between supplying power to the power storage element with the second DC voltage or insulating the second conversion unit and the power storage element. . Then, the fifth switch element and the sixth switch element are switched on or off to supply power stored in the power storage element to the load or to insulate the power storage element from the load. That is, electric power can be stored by applying the first DC voltage and the second DC voltage to the common power storage element while insulating the output of the first converter and the output of the second converter. Therefore, since the voltage output from the power storage element to the load is based on the divided voltage divided by the voltage dividing circuit, the voltage is lower than that of the circuit that does not divide the input voltage. Therefore, even when the input voltage is high, it is possible to prevent an excessively high voltage from being applied to the load. Furthermore, by dividing the input voltage, the voltage applied to the first conversion unit, the second conversion unit, and the power transmission insulating circuit is reduced, so that the apparatus is compared with a power conversion device that does not perform voltage division of the input voltage. The breakdown voltage performance required for the element used in the above can be lowered.

  According to the power conversion device according to the second aspect, particularly in the power conversion device according to the first aspect, in the power transmission insulating circuit, both the first switch element and the second switch element are on. And both the third switch element and the fourth switch element are turned off, and both the fifth switch element and the sixth switch element are turned off, Both the first switch element and the second switch element are off, and both the third switch element and the fourth switch element are off, and the fifth switch element and the second switch element are off. A first switch operation in which both of the six switch elements are turned on; both the first switch element and the second switch element are turned off; and After both the switch element and the fourth switch element are on and both the fifth switch element and the sixth switch element are off, the first switch element and the fourth switch element 2 switch elements are both off, both the third switch element and the fourth switch element are off, and both the fifth switch element and the sixth switch element are on. And a second switch operation for bringing the state into a state is selectively performed.

  According to the power conversion device of the second aspect, the power transmission insulating circuit is input from the first conversion unit while performing the first switch operation while insulating the first conversion unit and the load. Power can be supplied to the load. Further, by performing the second switch operation, the power input from the second conversion unit can be supplied to the load while insulating the second conversion unit and the load. Then, by selectively performing the first switch operation and the second switch operation, a short circuit between the output side of the first conversion unit and the output side of the second conversion unit is prevented, and the first conversion unit or the second conversion unit It is possible to prevent malfunction such as reverse current flow.

  The power conversion device according to a third aspect of the present invention is the power conversion device according to the second aspect, in particular, the power transmission insulating circuit alternately performs the first switch operation and the second switch operation. It is characterized by that.

  According to the power conversion device according to the third aspect, by alternately performing the first switch operation and the second switch operation, the operation of outputting the DC voltage output by the first converter to the load and the second converter It is possible to switch the operation of outputting the direct current voltage output to the load at an early cycle. Therefore, the switching frequency of each switch element can be increased, and the amount of power stored in the power storage element used in the device can be small. Therefore, by using a power storage element having a small electric capacity, the device can be reduced in size and cost.

  The power conversion device according to a fourth aspect of the present invention is the power conversion device according to any one of the first to third aspects, in particular, the first conversion unit includes the first switch element and the second switch element. The first DC voltage is output to the first input switch unit during a period in which both of the switch elements are on, and the second conversion unit is configured to output the third switch element and the fourth switch element. The second DC voltage is output to the second input switch section while both are on.

  According to the power converter of the fourth aspect, when the first converter outputs the first DC voltage, the first switch element and the second switch element are on, so that the power transmission insulation Electric power can be supplied to the load without using a power storage element that stores electric power output from the first converter to the circuit. Also, when a power storage element that stores the power output from the first converter is used in the power transmission insulating circuit, a power storage element having a large electric capacity is not required. When the second converter outputs the second DC voltage, since the third switch element and the fourth switch element are on, the power storage that stores the power output by the second converter to the power transmission insulating circuit Electric power can be supplied to the load without using an element or the like. Also, when a power storage element that stores the power output from the second conversion unit is used in the power transmission insulating circuit, a power storage element having a large electric capacity is not required. Therefore, by using a power storage element having a small electric capacity, the device can be reduced in size and cost.

  The power conversion device according to a fifth aspect of the present invention is the power conversion device according to any one of the first to fourth aspects, in particular, the first conversion unit and the second conversion unit are each the voltage dividing circuit A reactor to which the voltage generated is applied, and a current that flows through the reactor when it is turned on flows so as not to be supplied to the power transmission insulating circuit, and a current that flows through the reactor when it is turned off is the power transmission insulating circuit And a conversion switch element that generates an induced voltage in the reactor by switching from on to off, and the induced voltage generated in the reactor included in the first converter is the first And the induced voltage generated in the reactor included in the second converter is the second DC voltage, and the first converter and the second converter It said conversion switching element at one is off, the other of said conversion switching element is characterized in that turned on.

  According to the power conversion device according to the fifth aspect, the first conversion unit and the second conversion unit generate an induced voltage in the reactor by switching the conversion switch element on and off, and based on the induced voltage. Can be output as the first DC voltage or the second DC voltage. The conversion switch elements included in the first conversion unit and the second conversion unit are not turned on at the same time because one of them is turned off when the other is turned on. Therefore, since the time for increasing the current for generating the induced voltage in the reactor is shifted between the first conversion unit and the second conversion unit, the pulsation component of the current input to the power conversion device is increased. It is possible to suppress the loss that occurs in the power converter, and to improve the power factor.

  ADVANTAGE OF THE INVENTION According to this invention, the power converter device which can prevent supplying too high voltage to a load can be obtained, supplying DC power to a load, ensuring the insulation of a power supply and load. .

It is the figure which showed schematically the structure of the power converter device which concerns on embodiment of this invention. It is a figure showing the direction of the electric current and voltage input into a voltage dividing circuit and each booster circuit. 3 is a time chart showing the relationship between the state of each switch element and the operation of each booster circuit. It is the time chart which showed the example which does not perform operation | movement of each input switch part alternately. 10 is a time chart showing a modification of the relationship between the state of each switch element and the operation of each booster circuit. It is the figure which showed roughly the structure of the power converter device which concerns on the modification of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the element which attached | subjected the same code | symbol in different drawing shall show the same or corresponding element.

  FIG. 1 is a diagram schematically showing a configuration of a power conversion device 101 according to an embodiment of the present invention. The power conversion device 101 includes a rectifier circuit 10, a voltage divider circuit 11, booster circuits 12 and 13, a power transmission insulating circuit 14, and capacitors C3, C4, and C6. The voltage dividing circuit 11 includes a capacitor C1 and a capacitor C2. Boost circuit 12 includes winding L1, switching element Q1, and diode D1. Booster circuit 13 includes winding L2, switching element Q2, and diode D2. The power transmission insulating circuit 14 includes input switch units 21 and 22, an output switch unit 23, and a capacitor C5. Input switch unit 21 includes switch elements Q3 and Q4 and diodes D3 and D4. Input switch unit 22 includes switch elements Q5 and Q6 and diodes D5 and D6. Output switch unit 23 includes switch elements Q7 and Q8 and diodes D7 and D8. The switch elements Q1 to Q8 are, for example, IGBTs (Insulated Gate Bipolar 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 battery for driving such as EV and plug-in type HV, for example.

  The rectifier circuit 10 includes, for example, a diode bridge, and full-wave rectifies the AC power received from the AC power supply 201 and outputs it to the voltage divider circuit 11.

  FIG. 2 is a diagram showing the directions of current and voltage input to the voltage dividing circuit 11 and the boosting circuits 12 and 13. The voltage divider circuit 11 receives the input voltage V0 rectified by the rectifier circuit 10 and accumulates electric power in the capacitor C1 and the capacitor C2 connected in series, while the input voltage is changed between the voltage V1 across the capacitor C1 and the voltage across the capacitor C2. The voltage is divided to the voltage V2. The current I0 output from the rectifier circuit 10 is divided into a current I1 flowing through the winding L1 and a current I2 flowing through the winding L2, and flows into the booster circuits 12 and 13.

  The booster circuit 12 and the booster circuit 13 which are conversion units that convert the voltage divided by the voltage divider circuit 11 into a DC voltage are so-called boost chopper circuits. Winding L1 is connected between the first end of capacitor C1 and the collector of switch element Q1. Switch element Q1 includes a gate that receives a control signal from control unit 15, a collector connected to the first end of capacitor C3 via winding L1 and diode D1, a second end of capacitor C1, and a capacitor C3. And an emitter connected to the second end.

  Then, the booster circuit 12 receives the control signal from the control unit 15 and performs a boost based on the voltage V1 across the capacitor C1 by switching between a state in which the switch element Q1 is on and a state in which the switch element Q1 is off. The boosted voltage is output to the input switch section 21 and the capacitor C3 of the transmission insulating circuit 14. At this time, the diode D1 prevents a current from flowing backward from the capacitor C3 to the winding L1.

  The winding L2 is connected between the first end of the capacitor C2 and the collector of the switch element Q2. Switch element Q2 includes a gate that receives a control signal from control unit 15, a collector connected to a first end of capacitor C4 via winding L2 and diode D2, a second end of capacitor C2, and a capacitor C4. And an emitter connected to the second end.

  The booster circuit 13 receives a control signal from the control unit 15 and switches between a state in which the switch element Q2 is turned on and a state in which the switch element Q2 is turned off, thereby boosting the voltage based on the voltage V2 across the capacitor C2 and The boosted voltage is output to the input switch unit 22 and the capacitor C4 of the insulating circuit 14. At this time, the diode D2 prevents the current from flowing backward from the capacitor C4 to the winding L2.

  Input switch unit 21 receives a voltage boosted by booster circuit 12 by switch element Q3 and switch element Q4. Switch element Q3 has a gate for receiving a control signal from control unit 15, a collector connected to booster circuit 12, and an emitter connected to the first end of capacitor C5. The diode D3 is connected in parallel with the switch element Q3, the anode of the diode D3 is connected to the emitter of the switch element Q3, and the cathode of the diode D3 is connected to the collector of the switch element Q3. Switch element Q4 has a gate for receiving a control signal from control unit 15, a collector connected to the second end of capacitor C5, and an emitter connected to booster circuit 12. The diode D4 is connected in parallel with the switch element Q4, the anode of the diode D4 is connected to the emitter of the switch element Q4, and the cathode of the diode D4 is connected to the collector of the switch element Q4.

  The switch elements Q3 and Q4 of the input switch unit 21 are switched between a state in which both are on and a state in which both are off in accordance with a control signal output by the control unit 15. When both the switch element Q3 and the switch element Q4 are in the on state, the input switch unit 21 supplies the power output from the booster circuit 12 and the power stored in the capacitor C3 to the capacitor C5. Further, when both the switch element Q3 and the switch element Q4 are in the OFF state, the booster circuit 12, the capacitor C3, and the capacitor C5 are insulated.

  The diode D3 protects the switch element Q3 from a reverse current generated by switching of the switch element Q3. The diode D4 protects the switch element Q4 from a reverse current generated by switching of the switch element Q4.

  The input switch unit 22 receives the voltage boosted by the booster circuit 13 by the switch element Q5 and the switch element Q6. Switch element Q5 has a gate for receiving a control signal from control unit 15, a collector connected to booster circuit 13, and an emitter connected to the first end of capacitor C5. The diode D5 is connected in parallel with the switch element Q5, the anode of the diode D5 is connected to the emitter of the switch element Q5, and the cathode of the diode D5 is connected to the collector of the switch element Q5. Switch element Q6 has a gate for receiving a control signal from control unit 15, a collector connected to the second end of capacitor C5, and an emitter connected to booster circuit 13. The diode D6 is connected in parallel with the switch element Q6, the anode of the diode D6 is connected to the emitter of the switch element Q6, and the cathode of the diode D6 is connected to the collector of the switch element Q6.

  The switch elements Q5 and Q6 of the input switch unit 22 are switched between a state in which both are on and a state in which both are off in accordance with a control signal output by the control unit 15. When both the switch element Q5 and the switch element Q6 are in the on state, the input switch unit 22 supplies the power output from the booster circuit 13 and the power stored in the capacitor C4 to the capacitor C5. Further, when both the switch element Q5 and the switch element Q6 are in the off state, the booster circuit 13, the capacitor C4, and the capacitor C5 are insulated.

  The diode D5 protects the switch element Q5 from a reverse current generated by switching of the switch element Q5. The diode D6 protects the switch element Q6 from a reverse current generated by switching of the switch element Q6.

  The output switch unit 23 switches whether to supply the power stored in the capacitor C5 to the load 202. In output switch unit 23, switch element Q7 has a gate that receives a control signal from control unit 15, a collector connected to the first end of capacitor C5, and an emitter connected to the first end of capacitor C6. is doing. The diode D7 is connected in parallel with the switch element Q7, the anode of the diode D7 is connected to the emitter of the switch element Q7, and the cathode of the diode D7 is connected to the collector of the switch element Q7. Switch element Q8 has a gate for receiving a control signal from control unit 15, a collector connected to the second end of capacitor C6, and an emitter connected to the second end of capacitor C5. The diode D8 is connected in parallel with the switch element Q8, the anode of the diode D8 is connected to the emitter of the switch element Q8, and the cathode of the diode D8 is connected to the collector of the switch element Q8.

  The switch elements Q7 and Q8 of the output switch unit 23 are switched between a state in which both are on and a state in which both are off in accordance with a control signal output by the control unit 15. When both the switch element Q7 and the switch element Q8 are on, the output switch unit 23 supplies the power stored in the capacitor C5 to the capacitor C6 and the load 202. Further, when both switch element Q7 and switch element Q8 are in the OFF state, input switch unit 21, input switch unit 22, capacitor C5, capacitor C6 and load 202 are insulated.

  The diode D7 protects the switch element Q7 from a reverse current generated by switching of the switch element Q7. The diode D8 protects the switch element Q8 from a reverse current generated by switching of the switch element Q8.

  FIG. 3 is a time chart showing the relationship between the state of each switch element and the operation of the booster circuits 12 and 13. The voltage V0 is a full-wave rectified wave because the AC voltage input from the AC power supply 201 is rectified by the rectifier circuit 10. Since the voltage V1 and the voltage V2 are voltages obtained by dividing the voltage V0 by the voltage dividing circuit 11, the voltage V1 and the voltage V2 fluctuate according to the increase or decrease of the voltage V0. When capacitors having the same specifications are used for the capacitor C1 and the capacitor C2, the voltage V1 and the voltage V2 are half of the voltage V0.

  Then, when the voltage V1 is applied to the booster circuit 12, a current I1 that is a current flowing through the winding L1 is generated. When the switch element Q1 is in the on state, the current I1 flows through the winding L1 and a path through the switch element Q1. At this time, a magnetic flux is generated in the winding L1 by the current I1, and magnetic energy is accumulated in the winding L1.

  When the switch element Q1 is in the OFF state, an induced voltage is generated in the winding L1 by the magnetic energy accumulated in the winding L1. With this induced voltage, the booster circuit 12 boosts and outputs the output voltage. At this time, the current I1 is supplied to the capacitor C3 and the input switch unit 21. The output voltage of the booster circuit 12 is smoothed by the capacitor C3, and the boosted DC voltage is output to the input switch unit 21.

  That is, the booster circuit 12 operates as a so-called boost chopper circuit by switching on and off of the switch element Q1, and outputs a boosted DC voltage. The step-up rate of the DC voltage is controlled by the duty ratio of the switch element Q1. Further, when the booster circuit 12 operates, the current I1 has a waveform that increases and decreases during the period in which the switch element Q1 is in the OFF state while following the increase and decrease of the voltage V1. At this time, the switching frequency in the switch element Q1 is, for example, several kHz to several tens kHz.

  Similarly to the booster circuit 12, the booster circuit 13 operates as a so-called booster chopper circuit, and outputs a boosted DC voltage to the input switch unit 22. The step-up rate of the DC voltage is controlled by the duty ratio of the switch element Q2. Further, when the booster circuit 13 operates, the current I2 has a waveform that increases and decreases during the period in which the switch element Q2 is in the OFF state while following the increase and decrease of the voltage V2. At this time, the switching frequency of the switch element Q2 is, for example, several kHz to several tens of kHz.

  Since current I0 is the sum of current I1 and current I2 and the current charging capacitor C1 and capacitor C2, if the current charging capacitor C1 and capacitor C2 is sufficiently small, the waveform of current I0 is voltage V0. The waveform follows the increase / decrease. As shown in FIG. 3, if the period in which the switch element Q1 is on and the period in which the switch element Q2 is on are shifted, the peak of the pulsating component of the current I1 and the peak of the pulsating component of the current I2 are shifted. The pulsating component of the current I0 is suppressed.

  Referring to FIG. 3, control unit 15 turns on both switch elements Q3 and Q4 and turns off all of switch elements Q5 to Q8, and outputs power and capacitor output from booster circuit 12 by input switch unit 21. The first input switch control is performed to supply the power stored in C3 to the capacitor C5. Then, the control unit 15 turns on both the switch elements Q7 and Q8 and turns off all the switch elements Q3 to Q6, and the power stored in the capacitor C5 is supplied to the capacitors C6 and C6 by the output switch unit 23. The output switch supplied to the load 202 is controlled. As described above, the power transfer insulating circuit 14 operates each switch element by switching between the first input switch control and the output switch control, and insulates the boost circuit 12 and the load 202 from each other, while boosting the boost circuit 12. Is transmitted to the load 202.

  In the switch operation shown in FIG. 3, when the switch element Q1 is switched to the off state, both the switch elements Q3 and Q4 are switched to the on state. Since the booster circuit 12 is a so-called boost chopper circuit, the most output current immediately after the switching element Q1 is switched from the on state to the off state. Therefore, when a DC voltage is output from the booster circuit 12 and the output current is large, both the switch elements Q3 and Q4 are turned on, so that the amount of power that needs to be stored in the capacitor C3 is reduced.

  Control unit 15 turns on both switch elements Q5 and Q6 and turns off all of switch elements Q3 and Q4 and switch elements Q7 and Q8, and the power output from booster circuit 13 by input switch unit 22 and The second input switch control is performed to supply the power stored in the capacitor C4 to the capacitor C5. Then, the control unit 15 turns on both the switch elements Q7 and Q8 and turns off all the switch elements Q3 to Q6, and the power stored in the capacitor C5 is supplied to the capacitors C6 and C6 by the output switch unit 23. The output switch supplied to the load 202 is controlled. As described above, the power transmission insulating circuit 14 operates each switch element by switching between the second input switch control and the output switch control, and insulates the boost circuit 13 and the load 202 from each other, and Is transmitted to the load 202.

  In the switch operation shown in FIG. 3, when the switch element Q2 is switched to the off state, both the switch elements Q5 and Q6 are switched to the on state. Since the booster circuit 13 is a so-called boost chopper circuit, the most output current immediately after the switch element Q2 is switched from the on state to the off state. Therefore, when a DC voltage is output from the booster circuit 13 and the output current is large, both the switch elements Q5 and Q6 are turned on, so that the amount of power that needs to be stored in the capacitor C4 is reduced.

  When power is transmitted in the power transmission insulating circuit 14, the period in which both the switch element Q3 and the switch element Q4 are on does not overlap with the period in which both the switch element Q5 and the switch element Q6 are on. In addition, the control unit 15 controls each switch. That is, the operation of transmitting the power output from the booster circuit 12 to the load 202 and the operation of transmitting the power output from the booster circuit 13 to the load 202 are selectively performed.

  Further, all of the switch elements Q3 to Q8 are OFF during the period TA for performing the first input switch control, the second period TB for performing the second input switch control, and the period TC for performing the output switch control. A period TD is provided. Therefore, even when switching between the ON state and the OFF state of each switch element is not performed instantaneously, insulation between the booster circuit 12, the booster circuit 13, and the load 202 is ensured.

  As described above, the power conversion circuit 101 divides the input voltage by the voltage dividing circuit 11 and converts the divided voltage into a DC voltage by the boosting circuits 12 and 13. The power transmission insulating circuit 14 can transmit the power output from the booster circuits 12 and 13 to the load 202 while insulating the booster circuits 12 and 13 from the load 202.

  When the switch element Q3 and the switch element Q4 of the input switch unit 21 are on, the power output from the booster circuit 12 and the power stored in the capacitor C3 are supplied to the capacitor C5. At this time, the potential of the capacitor C5 is the same as the potential of the capacitor C3. Further, when the switch element Q5 and the switch element Q6 of the input switch unit 22 are in the on state, the power output from the booster circuit 13 and the power stored in the capacitor C4 are supplied to the capacitor C5. At this time, the potential of the capacitor C5 is the same as the potential of the capacitor C4. Here, although the potential of the capacitor C3 and the potential of the capacitor C4 are different, the potential of the capacitor C5 is brought into a floating state by the input switch unit 21, the input switch unit 22, and the output switch unit 23. That is, when the potential of the capacitor C5 becomes the same as the potential of the capacitor C3, the potential of the capacitor C5 is in a floating state with respect to the capacitor C4 and the load 202. When the potential of the capacitor C5 becomes the same as the potential of the capacitor C4, the potential of the capacitor C5 is in a floating state with respect to the capacitor C3 and the load 202. Therefore, the voltage output from the input switch unit 21 and the voltage output from the input switch unit 22 can be applied across the capacitor C5.

  The voltage boosted by the booster circuits 12 and 13 is a voltage divided by the voltage divider circuit 11. Therefore, the output voltage can be controlled to be lower than that of a circuit that converts power without performing voltage division. For example, when the AC power supply 201 is an AC voltage of 200V and the peak voltage is about 280V, when the voltage V1 and the voltage V2 are divided into half the voltage V0 by the voltage dividing circuit 11, the voltage V1 The peak voltage of the voltage V2 is about 140V. In this case, the voltage output from the booster circuits 12 and 13 is a voltage obtained by boosting the voltage of 140 V, and is approximately half the voltage output by the booster circuit that does not perform voltage division.

  That is, since the voltage output from the capacitor C5 to the load 202 is based on the divided voltage divided by the voltage dividing circuit 11, the voltage is lower than that of the circuit that does not divide the input voltage. Therefore, even when the input voltage is high, it is possible to prevent an excessively high voltage from being applied to the load. Furthermore, since the voltage applied to the booster circuits 12 and 13 and the power transmission insulating circuit 14 is reduced by lowering the input voltage, the elements used in the device as compared with the power converter that does not perform voltage division It is possible to reduce the pressure resistance required for the operation.

  Further, as a method for lowering the output voltage, there is a method using a step-down chopper circuit or a step-up / step-down chopper circuit instead of the step-up circuits 12 and 13, but when these methods are used, a switch for performing step-down or step-up / step-down is used. By switching the elements, the input current is cut off and the power factor of the circuit is deteriorated. On the other hand, in the power converter 101 using the booster circuits 12 and 13, the input current is not cut off, and the input current has a waveform that increases and decreases to follow the increase and decrease of the input voltage. Therefore, when a boost chopper circuit is used in the power conversion device of the present invention, it is possible to prevent the power factor from deteriorating while keeping the output voltage low.

  In addition, since the operation of transmitting the power output from the booster circuit 12 to the load 202 and the operation of transmitting the power output from the booster circuit 13 to the load 202 are selectively performed, a short circuit between the booster circuit 12 and the booster circuit 13 is performed. It is possible to prevent malfunction such as a current flowing backward to the booster circuit 12 or the booster circuit 13.

  Further, when the booster circuit 12 outputs a DC voltage, if both the switch element Q3 and the switch element Q4 are in the on state, the amount of power that needs to be stored in the capacitor C3 is reduced. When the booster circuit 13 outputs a DC voltage, if both the switch element Q5 and the switch element Q6 are on, the amount of power that needs to be stored in the capacitor C4 is small. Therefore, by using a capacitor having a small capacitance as the capacitor C3 and the capacitor C4, it is possible to reduce the size and cost of the device.

  Moreover, the pulsation component of the current input to the power conversion device 101 can be suppressed by shifting the period in which the switch element Q1 is in the off state and the period in which the switch element Q2 is in the off state. Therefore, it is possible to reduce the loss generated in the power conversion device 101 and improve the power factor.

  FIG. 3 shows an example in which the operation of transmitting the power output from the booster circuit 12 to the load 202 and the operation of transmitting the power output from the booster circuit 13 to the load 202 are alternately performed. It is not limited to the case where these operations are performed alternately. FIG. 4 is a time chart showing an example in which the operation of each input switch unit is not performed alternately.

  In the switch operation shown in FIG. 4, after the input switch unit 21 performs the operation of transmitting power twice in succession, the input switch unit 22 performs the operation of transmitting power twice in succession. Since the power output from the booster circuit 12 is stored in the capacitor C3 and the power output from the booster circuit 13 is stored in the capacitor C4, the power conversion device 101 operates to transmit the power output from the booster circuit 12 to the load 202. The power output from the booster circuit 12 and the booster circuit 13 can be transmitted to the load 202 without alternately performing the operation of transmitting the power output from the booster circuit 13 to the load 202.

  However, as shown in FIG. 3, if the operation of transmitting the power output from the booster circuit 12 to the load 202 and the operation of transmitting the power output from the booster circuit 13 to the load 202 are alternately performed, the switch element Q3 and the switch element The state in which both Q4 are on and the state in which both switch element Q5 and switch element Q6 are on are switched at a shorter cycle than when the above operations are not performed alternately as shown in FIG. Therefore, the cycle in which the electric power stored in the capacitors C3 and C4 is supplied to the load 202 via the capacitor C5 is also shortened, so that the amount of electric power that needs to be stored in the capacitors C3 and C4 can be reduced. Therefore, by using a capacitor having a small capacitance as the capacitor C3 and the capacitor C4, it is possible to reduce the size and cost of the device.

  FIG. 5 is a time chart showing a modified example of the relationship between the state of each switch element and the operation of the booster circuits 12 and 13.

  As shown in FIG. 5, the operation of the booster circuits 12 and 13 and the drive frequencies and timings of the switch elements in the input switch units 21 and 22 and the output switch unit 23 are configured so as not to be synchronized. Also good.

<Modification>
FIG. 6 is a diagram schematically showing the configuration of the power conversion device 102 according to a modification of the present invention. The power conversion device 102 includes a rectifier circuit 10, a voltage dividing circuit 11, boosting circuits 12, 13, a power transmission insulating circuit 16, and capacitors C3, C4, C6. The voltage dividing circuit 11 includes a capacitor C1 and a capacitor C2. Boost circuit 12 includes winding L1, switching element Q1, and diode D1. Booster circuit 13 includes winding L2, switching element Q2, and diode D2. The power transmission insulating circuit 16 includes input switch units 21 and 22, output switch units 23 and 24, and capacitors C5 and C7. Input switch unit 21 includes switch elements Q3 and Q4 and diodes D3 and D4. Input switch unit 22 includes switch elements Q5 and Q6 and diodes D5 and D6. Output switch unit 23 includes switch elements Q7 and Q8 and diodes D7 and D8. The output switch unit 24 includes switch elements Q9 and Q10 and diodes D9 and D10. The switch elements Q1 to Q10 are, for example, IGBTs (Insulated Gate Bipolar Transistors).

  The power conversion device 102 according to the modification of the present invention converts the AC power supplied from the AC power supply 201 into DC power and supplies it to the load 202 in the same manner as the power conversion device 101 described in the embodiment of the present invention. To do. The load 202 is a battery for driving such as EV and plug-in type HV, for example.

  And in power converter device 102 concerning the modification of the present invention, like power converter device 101 explained in the embodiment of the present invention, rectifier circuit 10 carries out full-wave rectification of the AC power received from AC power supply 201. To do. The voltage dividing circuit 11 divides the input voltage subjected to full-wave rectification, and outputs the divided voltage to the boosting circuits 12 and 13. The booster circuit 12 boosts the voltage based on the divided voltage, and outputs the boosted DC voltage to the input switch unit 21 of the power transmission insulating circuit 16. The booster circuit 13 boosts the voltage based on the divided voltage, and outputs the boosted DC voltage to the input switch unit 22 of the power transmission insulating circuit 16.

  The switch elements Q3 and Q4 of the input switch unit 21 are switched between a state in which both are on and a state in which both are off in accordance with a control signal output by the control unit 15. When both the switch element Q3 and the switch element Q4 are in the on state, the input switch unit 21 supplies the power output from the booster circuit 12 and the power stored in the capacitor C3 to the capacitor C5. Further, when both the switch element Q3 and the switch element Q4 are in the OFF state, the booster circuit 12, the capacitor C3, and the capacitor C5 are insulated.

  The switch elements Q5 and Q6 of the input switch unit 22 are switched between a state in which both are on and a state in which both are off in accordance with a control signal output by the control unit 15. When both the switch element Q5 and the switch element Q6 are in the on state, the input switch unit 22 supplies the power output from the booster circuit 13 and the power stored in the capacitor C4 to the capacitor C7. Further, when both the switch element Q5 and the switch element Q6 are in the OFF state, the booster circuit 13, the capacitor C4, and the capacitor C7 are insulated.

  The output switch unit 23 switches whether to supply the power stored in the capacitor C5 to the load 202. The switch elements Q7 and Q8 of the output switch unit 23 are switched between a state in which both are on and a state in which both are off in accordance with a control signal output by the control unit 15. When both the switch element Q7 and the switch element Q8 are on, the output switch unit 23 supplies the power stored in the capacitor C5 to the capacitor C6 and the load 202. Further, when both the switch element Q7 and the switch element Q8 are in the OFF state, the input switch unit 21 and the capacitor C5 are insulated from the capacitor C6 and the load 202.

  The output switch unit 24 switches whether to supply the power stored in the capacitor C7 to the load 202. The switch elements Q9 and Q10 of the output switch unit 24 are switched between a state in which both are on and a state in which both are off in accordance with a control signal output by the control unit 15. When both the switch element Q9 and the switch element Q10 are in the ON state, the output switch unit 24 supplies the power stored in the capacitor C7 to the capacitor C6 and the load 202. Further, when both the switch element Q9 and the switch element Q10 are in the OFF state, the input switch unit 22 and the capacitor C7 are insulated from the capacitor C6 and the load 202.

  The electric power output from the output switch unit 23 and the output switch unit 24 is smoothed by being stored in the capacitor C6, and a DC voltage is output to the load 202.

  Here, similarly to the power converter 101, when the switch element Q7 and the switch element Q8 of the output switch unit 23 are in the on state, the power stored in the capacitor C5 is supplied to the capacitor C6. At this time, the potential of the capacitor C6 is the same as the potential of the capacitor C5. Further, when the switch element Q9 and the switch element Q10 of the output switch unit 24 are in the on state, the power stored in the capacitor C7 is supplied to the capacitor C6. At this time, the potential of the capacitor C6 is the same as the potential of the capacitor C7. Here, although the potential of the capacitor C5 and the potential of the capacitor C7 are different, the output switch unit 23 and the output switch unit 24 cause the potential of the capacitor C6 to be in a floating state. That is, when the potential of the capacitor C6 becomes the same as the potential of the capacitor C5, the potential of the capacitor C6 is in a floating state with respect to the capacitor C7. When the potential of the capacitor C6 becomes the same as the potential of the capacitor C7, the potential of the capacitor C6 is in a floating state with respect to the capacitor C5. Therefore, the voltage output from the output switch unit 23 and the voltage output from the output switch unit 24 can be applied to both ends of the capacitor C6. Therefore, the power transmission insulating circuit 16 can transmit the power output from the booster circuits 12 and 13 to the load 202 while insulating the booster circuits 12 and 13 from the load 202.

  As described above, by controlling on / off of switch elements Q1 to Q10 by control unit 15, power conversion device 102 can obtain the same effects as power conversion device 101 according to the embodiment of the present invention. .

  In the embodiment of the present invention, the example in which the step-up chopper circuit is used for the conversion unit that converts the voltage divided by the voltage dividing circuit 11 into the direct-current voltage has been described. It is not limited to chopper circuits. For example, another circuit capable of receiving a divided voltage and outputting a DC voltage at a voltage level to be applied to the load 202, such as a step-up / step-down chopper circuit or a step-down chopper circuit, may be used.

  In the embodiment of the present invention, the example in which the voltage dividing circuit 11 divides the input voltage into two has been described. However, in the present invention, the voltage dividing circuit 11 is limited to a circuit that divides the voltage into two. It is not a thing. The voltage dividing circuit used in the present invention may be a circuit that divides an input voltage into three or more. In the power conversion device in that case, the divided voltage divided into three or more is converted into a DC voltage by each conversion unit, and the DC voltage output by each conversion unit by the power transmission insulating circuit is shared by the capacitors C5 and the like. Any device can be used as long as it can output to this circuit.

  The embodiment disclosed this time 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 meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 10 Rectifier circuit 11 Voltage divider circuit 12, 13 Booster circuit 14 Power transmission insulation circuit 15 Control part 21,22 Input switch part 23,24 Output switch part C1-C7 Capacitor D1-D10 Diode Q1-Q10 Switch element 101,102 Power Converter 201 AC power supply 202 Load

Claims (5)

A power conversion device for converting input power to DC power and supplying it to a load,
A voltage dividing circuit that divides an input voltage to generate a first divided voltage and a second divided voltage;
A first converter that converts the first divided voltage into a first DC voltage;
A second converter for converting the second divided voltage into a second DC voltage;
An insulating circuit for power transmission that supplies the first DC voltage and the second DC voltage to the load while insulating the first converter and the second converter from the load;
With
The power transmission insulating circuit is:
A power storage element having a first end and a second end;
A first switch element connected between the first converter and the first end of the electricity storage element; and a second switch element connected between the first converter and the second end of the electricity storage element. A first input switch unit including a switch element for supplying the first DC voltage to the storage element;
A third switch element connected between the second conversion part and the first end of the electricity storage element; and a fourth switch element connected between the second conversion part and the second end of the electricity storage element. A second input switch unit including a switch element for supplying the second DC voltage to the storage element;
A fifth switch element connected between the first end of the electricity storage element and the load; and a sixth switch element connected between the second end of the electricity storage element and the load; An output switch unit for supplying power stored in the storage element to the load;
Including a power conversion device. The power transmission insulating circuit is:
Both the first switch element and the second switch element are on, and both the third switch element and the fourth switch element are off, and the fifth switch element and the After both of the sixth switch elements are in the off state, both the first switch element and the second switch element are off, and the third switch element and the fourth switch element A first switch operation in which both of the fifth switch element and the sixth switch element are turned on,
Both the first switch element and the second switch element are off, and both the third switch element and the fourth switch element are on, and the fifth switch element and the After both of the sixth switch elements are in the off state, both the first switch element and the second switch element are off, and the third switch element and the fourth switch element And a second switch operation in which both of the fifth switch element and the sixth switch element are on,
The power conversion device according to claim 1, wherein the power conversion device is selectively performed.   The power converter according to claim 2, wherein the power transmission insulating circuit alternately performs the first switch operation and the second switch operation. The first conversion unit outputs the first DC voltage to the first input switch unit during a period in which both the first switch element and the second switch element are on,
The second conversion unit outputs the second DC voltage to the second input switch unit during a period in which both the third switch element and the fourth switch element are on. 4. The power conversion device according to any one of 3. The first conversion unit and the second conversion unit are respectively
A reactor to which a voltage generated by the voltage dividing circuit is applied;
When turned on, the current flowing through the reactor flows so as not to be supplied to the power transmission insulating circuit, and when the power is turned off, the current flowing through the reactor flows so as to be supplied to the power transmission insulating circuit. A conversion switch element that generates an induced voltage in the reactor by switching to
Including
The induced voltage generated in the reactor included in the first converter is the first DC voltage,
The induced voltage generated in the reactor included in the second converter is the second DC voltage,
5. The power conversion device according to claim 1, wherein when one of the first conversion unit and the second conversion unit is turned off, the other conversion switch device is turned on. 6. .

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