JP2015035928A - Bidirectional ac/dc conversion device, intermittent conversion method, and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bidirectional AC/DC conversion device that allows reducing power consumption of a converter and processing load of a drive circuit in performing DC/AC conversion, an intermittent conversion method of the converter in the bidirectional AC/DC conversion device, and a computer program to achieve the intermittent conversion method.SOLUTION: A bidirectional AC/DC conversion device 1 includes: an inverter 5 bidirectionally converting an alternate current and a direct current; a converter 10 bidirectionally voltage-converting a direct current; a capacitor C2 smoothing a DC voltage converted by the inverter 5 and a DC voltage converted in one direction by the converter 10; and a control unit 9 controlling on and off of conversion by the converter 10 and controlling direction of the conversion by the inverter 5 and the converter 10. When a voltage of the capacitor C2 is lower than a predetermined voltage, the control unit 9 turns on the conversion in the one direction.

Description

  The present invention is a bidirectional AC comprising: an inverter that bidirectionally converts an AC voltage and a DC voltage; a converter that bidirectionally converts the DC voltage; and a capacitor that smoothes the DC voltage converted by the inverter and the converter. The present invention relates to a DC / DC converter, an intermittent conversion method for a converter in the bidirectional AC / DC converter, and a computer program for realizing the intermittent conversion method.

  A plug-in hybrid vehicle (PHEV) that is equipped with an AC / DC converter that converts an AC voltage supplied from a commercial power source for household use into a DC voltage, and that charges the battery with the DC voltage converted by the AC / DC converter. : Electric vehicles such as Plug-in Hybrid Electric Vehicle (EV) and Electric Vehicle (EV) are widely used.

  In recent years, it is expected to use a battery of an electric vehicle such as a plug-in hybrid vehicle or an electric vehicle as a disaster or emergency power source. In order to use the battery as an emergency power source, it is necessary to perform bidirectional conversion from AC voltage to DC voltage and from DC voltage to AC voltage.

  For example, Patent Literature 1 discloses a bidirectional converter (corresponding to a bidirectional AC / DC converter) that bidirectionally converts an AC voltage from an AC power source and a DC voltage from a battery. This bidirectional converter is connected in cascade to the AC / DC converter and a bidirectional AC / DC converter that functions as an inverter and a synchronous rectifier circuit having a power factor correction function at the time of battery charging and discharging. And a bidirectional DC / DC converter. A smoothing capacitor (hereinafter referred to as capacitor A) is provided at a connection point between the AC / DC converter and the DC / DC converter.

  The DC / DC conversion unit includes two full bridge circuits provided on the primary side and the secondary side of the transformer, and each full bridge circuit functions as an inverter and a rectifier circuit. Specifically, when the battery is charged, the full bridge circuit on each of the AC / DC conversion unit side and the battery side functions as an inverter and a rectification circuit, and when the battery is discharged, each of the battery side and the AC / DC conversion unit side The full bridge circuit functions as an inverter and a rectifier circuit.

JP 2010-178666 A

  However, when an AC voltage is supplied to the outside by the bidirectional converter disclosed in Patent Document 1, the AC / DC conversion unit and the DC / DC conversion unit are turned on regardless of whether an external power load is connected. In order to continue, there has been a problem that the power consumption of the bidirectional converter and the processing load of the drive circuit that drives each conversion unit become larger than necessary.

  The present invention has been made in view of such circumstances, and an object thereof is a bidirectional AC capable of reducing the power consumption of the converter and the processing load of the drive circuit when performing DC / AC conversion. An object of the present invention is to provide a DC / DC conversion device, an intermittent conversion method of a converter in the bidirectional AC / DC conversion device, and a computer program for realizing the intermittent conversion method.

  The bidirectional AC / DC converter according to the present invention includes an inverter that bidirectionally converts an AC voltage and a DC voltage, a converter that bidirectionally converts a DC voltage, a DC voltage converted by the inverter, and the converter. Bidirectional AC / DC converter comprising a capacitor for smoothing a DC voltage converted in one direction, a control unit for controlling on / off of conversion by the converter, and a control unit for controlling the direction of conversion by the inverter and converter When the direction of conversion by the converter is the one direction, the control unit detects a voltage of the capacitor, and whether the voltage detected by the detection unit is lower than a predetermined voltage. And determining that the determination unit is low, the conversion by the converter is turned on.

  The intermittent conversion method according to the present invention includes an inverter that converts AC voltage and DC voltage bidirectionally, a converter that converts DC voltage bidirectionally, and the DC voltage converted by the inverter and the converter in one direction. The converter in the bidirectional AC / DC conversion apparatus comprising: a capacitor that smoothes the DC voltage converted into a converter; a control unit that controls on / off of conversion by the converter; and a control unit that controls the direction of conversion by the inverter and the converter. In the intermittent conversion method of intermittently turning on conversion according to the above, the control unit detects the voltage of the capacitor when the direction of conversion by the converter is the one direction, A step of determining whether or not the detected voltage is lower than a predetermined voltage; A step of turning on conversion by the converter; a step of detecting the voltage of the capacitor when the conversion is turned on in the step; and a voltage detected in the step being equal to or higher than a second voltage higher than the predetermined voltage. A step of determining whether or not the converter is turned off when it is determined that the voltage is equal to or higher than the second voltage in the step.

  The computer program according to the present invention includes an inverter that converts AC voltage and DC voltage bidirectionally, a converter that converts DC voltage bidirectionally, the DC voltage converted by the inverter, and the converter converts the voltage in one direction. Conversion by the converter in a bidirectional AC / DC conversion device comprising a capacitor for smoothing the DC voltage, a control unit for controlling on / off of conversion by the converter, and a control unit for controlling the direction of conversion by the inverter and converter Is a computer program for intermittently turning on the computer that constitutes the control unit, wherein the computer detects the voltage of the capacitor when the conversion direction by the converter is the one direction. And the voltage detected in the step is lower than a predetermined voltage. A step of determining whether or not the voltage is low in the step, a step of turning on conversion by the converter, a step of detecting the voltage of the capacitor when the conversion is turned on in the step, and Determining whether or not the detected voltage is equal to or higher than a second voltage higher than the predetermined voltage; and when determining that the detected voltage is equal to or higher than the second voltage, turning off conversion by the converter; Is executed.

According to the present invention, when performing DC / AC conversion in the entire apparatus, when the voltage of the capacitor is lower than a predetermined voltage, the conversion by the converter is turned on to store electric power in the capacitor, and the voltage of the capacitor is increased.
Therefore, when performing DC / AC conversion, it is possible to reduce the power consumption of the converter and the processing load of the drive circuit.

It is a circuit diagram which shows one structural example of the bidirectional | two-way AC / DC conversion apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows one structural example of a control part. It is a flowchart which shows the process sequence of CPU which turns on the conversion by a converter intermittently with the bidirectional | two-way AC / DC converter which concerns on Embodiment 1 of this invention. It is a wave form diagram which shows the time change of the voltage of a capacitor when the conversion by a converter is turned on intermittently. It is a flowchart which shows the process sequence of CPU which turns on the conversion by a converter intermittently with the bidirectional | two-way AC / DC converter which concerns on Embodiment 2 of this invention.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described.

  The bidirectional AC / DC converter according to the present invention includes an inverter that bidirectionally converts an AC voltage and a DC voltage, a converter that bidirectionally converts a DC voltage, a DC voltage converted by the inverter, and the converter. Bidirectional AC / DC converter comprising a capacitor for smoothing a DC voltage converted in one direction, a control unit for controlling on / off of conversion by the converter, and a control unit for controlling the direction of conversion by the inverter and converter When the direction of conversion by the converter is the one direction, the control unit detects a voltage of the capacitor, and whether the voltage detected by the detection unit is lower than a predetermined voltage. And determining that the determination unit is low, the conversion by the converter is turned on.

  In the bidirectional AC / DC converter according to the present invention, when the control unit turns on the conversion by the converter, the voltage detected by the detection unit is equal to or higher than a second voltage higher than the predetermined voltage. A second determination unit for determining whether or not the conversion by the converter is turned off when the second determination unit determines that the second voltage is equal to or higher than the second voltage.

  In the bidirectional AC / DC conversion device according to the present invention, the control unit has a timer that starts timing when the conversion by the converter is turned on. When the timer counts a predetermined time, the control unit The conversion is turned off.

  In the bidirectional AC / DC converter according to the present invention, the converter includes a second inverter and a third inverter that bidirectionally convert a DC voltage and an AC voltage, and an AC converted by the second inverter and the third inverter, respectively. A transformer in which a voltage is applied to the primary and secondary sides.

  The intermittent conversion method according to the present invention includes an inverter that converts AC voltage and DC voltage bidirectionally, a converter that converts DC voltage bidirectionally, and the DC voltage converted by the inverter and the converter in one direction. The converter in the bidirectional AC / DC conversion apparatus comprising: a capacitor that smoothes the DC voltage converted into a converter; a control unit that controls on / off of conversion by the converter; and a control unit that controls the direction of conversion by the inverter and the converter. In the intermittent conversion method of intermittently turning on conversion according to the above, the control unit detects the voltage of the capacitor when the direction of conversion by the converter is the one direction, A step of determining whether or not the detected voltage is lower than a predetermined voltage; A step of turning on conversion by the converter; a step of detecting the voltage of the capacitor when the conversion is turned on in the step; and a voltage detected in the step being equal to or higher than a second voltage higher than the predetermined voltage. A step of determining whether or not the converter is turned off when it is determined that the voltage is equal to or higher than the second voltage in the step.

  The computer program according to the present invention includes an inverter that converts AC voltage and DC voltage bidirectionally, a converter that converts DC voltage bidirectionally, the DC voltage converted by the inverter, and the converter converts the voltage in one direction. Conversion by the converter in a bidirectional AC / DC conversion device comprising a capacitor for smoothing the DC voltage, a control unit for controlling on / off of conversion by the converter, and a control unit for controlling the direction of conversion by the inverter and converter Is a computer program for intermittently turning on the computer that constitutes the control unit, wherein the computer detects the voltage of the capacitor when the conversion direction by the converter is the one direction. And the voltage detected in the step is lower than a predetermined voltage. A step of determining whether or not the voltage is low in the step, a step of turning on conversion by the converter, a step of detecting the voltage of the capacitor when the conversion is turned on in the step, and Determining whether or not the detected voltage is equal to or higher than a second voltage higher than the predetermined voltage; and when determining that the detected voltage is equal to or higher than the second voltage, turning off conversion by the converter; Is executed.

In the present invention, a DC voltage obtained by converting a DC voltage from the outside in one direction by the converter is smoothed by a capacitor and applied to the inverter, and an AC voltage obtained by converting the DC voltage by the inverter is supplied to the outside. The Further, a DC voltage obtained by converting an external AC voltage by an inverter is smoothed by a capacitor and applied to the converter, and a DC voltage obtained by converting the DC voltage in the other direction is supplied to the outside. When DC / AC conversion is performed in the entire apparatus with the conversion direction by the converter as the one direction, conversion by the converter is turned on when the voltage of the capacitor is lower than a predetermined voltage.
Thereby, the conversion by the converter is turned off until the electric power stored in the capacitor is consumed in the inverter and outside and the voltage of the capacitor drops below a predetermined voltage.

In the present invention, when conversion by the converter is turned on, conversion by the converter is turned off when the voltage of the capacitor becomes equal to or higher than a second voltage higher than a predetermined voltage.
Thereby, the relationship between the voltage of the capacitor and the on / off of the conversion by the converter has a hysteresis characteristic. For this reason, the ON time and OFF time of conversion by the converter are appropriately ensured, and the voltage of the capacitor is maintained at a voltage between the predetermined voltage and the second voltage.

In the present invention, when the conversion by the converter is turned on, the time measurement by the timer is started, and when the timer times the predetermined time, the conversion by the converter is turned off.
Thereby, the on-time of conversion by the converter becomes constant, and the off-time is appropriately controlled according to the magnitude of the alternating current supplied to the external power load.

In the present invention, the converter includes the second and third inverters that convert the DC voltage and the AC voltage bidirectionally, and the transformer that interconnects them, and the second (or third) The AC voltage converted from the DC voltage by the inverter is applied to the primary side (or secondary side) of the transformer, and the AC voltage from the secondary side (or primary side) of the transformer is converted to the third (or first) 2) Inverter converts to DC voltage.
As a result, the circuit portion for converting the voltage in the apparatus is unified to a bidirectional inverter, the circuit configuration is simplified, and the drive control is shared.

[Details of the embodiment of the present invention]
Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
(Embodiment 1)
FIG. 1 is a circuit diagram showing a configuration example of a bidirectional AC / DC conversion apparatus according to Embodiment 1 of the present invention. In the figure, reference numeral 1 denotes a bidirectional AC / DC converter, and the bidirectional AC / DC converter 1 is mounted on an electric vehicle such as a plug-in hybrid vehicle or an electric vehicle, for example, so that an AC voltage and a DC voltage are bidirectional. It is an insulation type conversion device for conversion.

  The AC power supply 2 is connected to the AC input terminals T1 and T2 of the bidirectional AC / DC converter 1 via a charging cable (both not shown) that is detachably attached to the inlet of the electric vehicle, for example. Furthermore, AC output terminals T5 and T6 are connected in parallel. AC output terminals T5 and T6 are, for example, AC outlets provided in an electric vehicle. Any one of the AC input terminals T1 and T2 or the AC output terminals T5 and T6 may be connected to one terminal pair of the noise filter 4 described later by a switching circuit using a relay contact.

  Both ends of the battery 3 are connected to the DC input / output terminals T3 and T4 of the bidirectional AC / DC converter 1 via relay contacts 31 and 33 included in an external contact box (not shown). A series circuit of a resistor R1 and a relay contact 32 is connected in parallel at both ends of the relay contact 31 by a contact box.

  In the bidirectional AC / DC converter 1, one terminal pair is connected to the AC input terminals T1 and T2 and the AC output terminals T5 and T6, and the AC voltage and the AC output terminal T5 input from the AC input terminals T1 and T2. The noise input / output terminals T51 and T52 are connected to the noise filter 4 for removing high-frequency noise contained in the AC voltage output from T6 and the other terminal pair of the noise filter 4 via the choke coils L1 and L2, respectively. The inverter 5 that converts AC voltage and DC voltage bidirectionally, and one DC input / output terminal T61, T62 are connected to the DC input / output terminals T53, T54 of the inverter 5 to convert the DC voltage bidirectionally. Converter 10 that controls the inverter 5 and the converter 9 that controls voltage conversion by the converter 10. A capacitor C1 that smoothes the AC voltage converted by the inverter 5 is connected in parallel to the other terminal pair of the noise filter 4.

  The converter 10 includes inverters (second and third inverters) 6 and 8 that convert a DC voltage and an AC voltage bidirectionally, and a transformer 7 that connects the inverters 6 and 8 to each other. The transformer 7 is insulated between the primary side and the secondary side, and the primary side and the secondary side are respectively connected to the AC input / output terminals T63 and T64 of the inverter 6 and the AC input / output terminals T81 and T82 of the inverter 8. It is connected. One DC input / output terminals T61 and T62 of the converter 10 also serve as DC input / output terminals T61 and T62 of the inverter 6, and the other DC input / output terminals T83 and T84 of the converter 10 are DC input / output terminals T83 and T83 of the inverter 8, respectively. Also serves as T84.

  The bidirectional AC / DC converter 1 is also connected in parallel to the DC input / output terminals T53 and T54 of the inverter 5 and the DC input / output terminals T61 and T62 of the converter 10, and the DC voltage converted by the inverter 5 and A capacitor C2 for smoothing the DC voltage converted by the converter 10 in one direction and the other DC input / output terminals T83 and T84 of the converter 10 connected in series, and the DC voltage converted by the converter 10 in the other direction A smoothing choke coil L3 and a capacitor C3 are provided. Both ends of the capacitor C3 are connected to DC input / output terminals T3 and T4. One end of the capacitors C2 and C3 on the plus side is connected to the control unit 9. The capacitance value of the capacitor C2 is, for example, about 1 mF.

  The inverter 5 includes a switching element such as an IGBT (Insulated Gate Bipolar Transistor) and a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) configured as a full bridge. In the first embodiment, IGBTs 51, 52, 53, and 54 are used as switching elements.

  The emitter of the IGBT 51 and the collector of the IGBT 52 are connected to the AC input / output terminal T51 of the inverter 5 connected to one end of the choke coil L1. The emitter of the IGBT 53 and the collector of the IGBT 54 are connected to the AC input / output terminal T52 of the inverter 5 connected to one end of the choke coil L2. The collectors of the IGBTs 51 and 53 are connected to the DC input / output terminal T53 of the inverter 5. The emitters of the IGBTs 52 and 54 are connected to the DC input / output terminal T54 of the inverter 5, respectively. Diodes 55, 56, 57, and 58 are connected in reverse parallel between the collectors and emitters of the IGBTs 51, 52, 53, and 54, respectively.

  When the inverter 5 converts AC voltage into DC voltage, the AC voltage applied to the AC input / output terminals T51, T52 from one end of each of the choke coils L1, L2 is switched by the IGBT 52 (or 54), and the choke coils L1, L2 are switched. The DC voltage induced in L2 is output to the DC input / output terminals T53 and T54 via the diodes 55 and 58 (or 57 and 56). Thereby, the power factor of the alternating current power supplied from the alternating current power supply 2 is improved and rectified. When the inverter 5 converts a DC voltage into an AC voltage, the polarity of the DC voltage applied to the DC input / output terminals T53 and T54 is alternately changed by turning on and off the IGBTs 51 and 54 and the IGBTs 53 and 52 alternately. Inverted and output from AC input / output terminals T51 and T52.

  The inverter 6 is configured by configuring the IGBTs 61, 62, 63, and 64 into a full bridge. The collectors of the IGBTs 61 and 63 are connected to the DC input / output terminal T61 of the inverter 6. The IGBTs 62 and 64 are connected to the DC input / output terminal T62 of the inverter 6, respectively. The emitter of the IGBT 61 and the collector of the IGBT 62 are connected to the AC input / output terminal T 63 of the inverter 6. The emitter of the IGBT 63 and the collector of the IGBT 64 are connected to the AC input / output terminal T 64 of the inverter 6. Diodes 65, 66, 67, and 68 are connected in antiparallel between the collectors and emitters of the IGBTs 61, 62, 63, and 64, respectively.

  When the inverter 6 converts a DC voltage into an AC voltage, the control unit 9 alternately turns on / off the IGBTs 61 and 64 and the IGBTs 63 and 62 to thereby change the DC voltage applied to the DC input / output terminals T61 and T62. The polarities are alternately inverted and output from the AC input / output terminals T63 and T64. This AC voltage is applied to AC input / output terminals T81 and T82 of the inverter 8 via the transformer 7. When the inverter 6 converts the AC voltage into the DC voltage, the AC voltage applied to the AC input / output terminals T63 and T64 while the control unit 9 turns off the IGBTs 61, 62, 63, and 64 is converted into the diode 65. , 66, 67, 68 are full-wave rectified by a diode bridge and output from DC input / output terminals T61, T62.

  The inverter 8 comprises IGBTs 81, 82, 83, and 84 configured as a full bridge. The emitter of the IGBT 81 and the collector of the IGBT 82 are connected to the AC input / output terminal T 81 of the inverter 8. The emitter of IGBT 83 and the collector of IGBT 84 are connected to the AC input / output terminal T 82 of the inverter 8. The collectors of the IGBTs 81 and 83 are connected to the DC input / output terminal T83 of the inverter 8. The emitters of the IGBTs 82 and 84 are connected to the DC input / output terminal T84 of the inverter 8. Diodes 85, 86, 87, and 88 are connected in antiparallel between the collectors and emitters of the IGBTs 81, 82, 83, and 84, respectively.

  When the inverter 8 converts the AC voltage into the DC voltage, the AC voltage applied to the AC input / output terminals T81 and T82 while the control unit 9 turns off the IGBTs 81, 82, 83, and 84 is connected to the diode 85. , 86, 87, 88 are full-wave rectified by a diode bridge and output from DC input / output terminals T83, T84. When the inverter 8 converts a DC voltage into an AC voltage, the control unit 9 alternately turns on / off the IGBTs 81 and 84 and the IGBTs 83 and 82, so that the DC voltage applied to the DC input / output terminals T 83 and T 84 is changed. The polarities are alternately inverted and output from the AC input / output terminals T81 and T82. This AC voltage is applied to the AC input / output terminals T63 and T64 of the inverter 6 via the transformer 7.

  The control unit 9 controls on / off of the conversion by the inverter 5 and control of the direction of conversion by the inverter 5 by controlling on / off of the IGBTs 51, 52, 53, 54. The control unit 9 also controls the on / off of the IGBTs 61, 62, 63, 64 and the on / off of the IGBTs 81, 82, 83, 84 to control the converter 10 including the inverters 6, 8. The control for turning on / off the conversion by and the conversion direction by the converter 10 are performed. That is, when the conversion direction by the converter 10 is set to one direction, the control unit 9 causes the inverter 8 to convert a DC voltage into an AC voltage and causes the inverter 6 to convert the AC voltage into a DC voltage. When the conversion direction by the converter 10 is set to another direction, the control unit 9 causes the inverter 6 to convert a DC voltage into an AC voltage and causes the inverter 8 to convert the AC voltage into a DC voltage.

  The control unit 9 further controls the on / off of the IGBTs 51, 52, 53, 54, the on / off of the IGBTs 61, 62, 63, 64, and the on / off of the IGBTs 81, 82, 83, 84 in association with each other. Thus, the direction of conversion by the inverter 5 and the converter 10 is matched. That is, when the AC voltage is converted into the DC voltage by the bidirectional AC / DC converter 1, the control unit 9 causes the inverter 5 to convert the AC voltage into the DC voltage and changes the conversion direction by the converter 10 to another direction. . When the bidirectional AC / DC converter 1 converts a DC voltage to an AC voltage, the control unit 9 changes the direction of conversion by the converter 10 to one direction and causes the inverter 5 to convert the DC voltage to an AC voltage. .

Next, details of the control unit 9 will be described.
FIG. 2 is a block diagram illustrating a configuration example of the control unit 9. The control unit 9 includes a CPU 91 that controls the operation of each unit in the control unit 9. The CPU 91 stores a storage unit 92 that stores information such as a control program, a RAM 93 that stores temporarily generated information, In addition, the communication unit 94 is connected to each other via a CAN bus (not shown). Communication performed by the communication unit 94 is not limited to CAN communication. The CPU 91 also supplies a drive signal to the timer 95 for measuring time, the A / D converter 96 for detecting the voltages of the capacitors C2 and C3, and the gates of the IGBTs constituting the inverters 5, 6 and 8. The drive unit 97 is connected to the bus.

  The CPU 91 executes processing for realizing the bidirectional AC / DC conversion device 1 according to Embodiment 1 of the present invention and intermittent conversion processing according to a control program stored in advance in the storage unit 92 and a computer program 99 described later. To do.

  The storage unit 92 includes a nonvolatile memory such as an EEPROM (Electrically Erasable Programmable ROM: registered trademark), for example, and stores a computer program 99 for the CPU 91 to execute the intermittent conversion processing according to the first embodiment of the present invention. ing. When the computer program 99 is recorded on a recording medium 98 such as a CD (Compact Disc) -ROM, a DVD (Digital Versatile Disc) -ROM, and a hard disk drive, which are portable media recorded in a readable manner, the CPU 91 The computer program 99 may be read from the recording medium 98 and stored in the storage unit 92 in advance.

  The RAM 93 is a readable / writable memory such as a DRAM (Dynamic RAM) and an SRAM (Static RAM). The RAM 93 may be preloaded with the control program and the computer program 99 stored in the storage unit 92. In this case, the control program and the computer program 99 are executed on the RAM 93.

  The communication unit 94 is a circuit that receives instruction signals such as a charge instruction that instructs conversion from an AC voltage to a DC voltage, a discharge instruction that instructs conversion from a DC voltage to an AC voltage, and an end instruction that instructs the end of conversion. is there. The instruction signal received by the communication unit 94 is notified to the CPU 91.

  1 and 2, when the battery 3 is connected to the DC input / output terminals T3 and T4 under the control of the external contact box, the relay contacts 32 and 33 are first turned on. Thereby, even when the voltage of the capacitor C3 is lowered, the current flowing into the capacitor C3 is limited by the resistor R1 to prevent the inrush current. Thereafter, when the voltage of the capacitor C3 becomes substantially equal to the voltage of the battery 3, the relay contact 31 is turned on, so that the DC input / output terminals T3 and T4 and the battery 3 are connected without the resistor R1. . In this way, so-called precharge is performed on the capacitor C3.

  Control based on an instruction signal from the outside in a state where the precharge for the capacitor C3 is completed and the AC power supply 2 is connected to the AC input terminals T1 and T2 via the charging cable (or not connected). By performing the above, the bidirectional AC / DC converter 1 operates as an AC / DC converter (or DC / AC inverter).

  For example, when the CPU 91 is notified of a charging instruction from the communication unit 94, the drive unit 97 causes the inverter 5 to convert an AC voltage into a DC voltage and sets the conversion direction by the converter 10 to another direction. Thereby, the alternating voltage applied to alternating current input terminal T1, T2 is converted into a direct current voltage, and the battery 3 is charged with the direct current voltage output from direct current input / output terminal T3, T4.

  When the CPU 91 is notified of a discharge instruction from the communication unit 94, the drive unit 97 causes the converter 10 to change the direction of conversion to one direction and causes the inverter 5 to convert a DC voltage into an AC voltage. As a result, the DC voltage applied from the battery 3 to the DC input / output terminals T3 and T4 is converted into an AC voltage, and the converted AC voltage is output from the AC output terminals T5 and T6. In this case, an AC voltage not linked to the AC power supply 2 is output from the AC output terminals T5 and T6. An external power load (not shown) is appropriately connected to the AC output terminals T5 and T6.

  When the CPU 91 is notified of the end instruction from the communication unit 94, the conversion by the inverter 5 is turned off by stopping the on / off of the IGBTs 51, 52, 53, 54 by at least the driving unit 97. Thereby, AC / DC conversion or DC / AC conversion by the whole apparatus is turned off.

  As described above, by charging / discharging the battery 3 using the bidirectional AC / DC converter 1 that bidirectionally converts AC voltage and DC voltage, the battery 3 is used as a disaster or emergency power source. It becomes possible.

  When the CPU 91 is not notified of the charging instruction and the discharging instruction from the communication unit 94 or when the CPU 91 is notified of the termination instruction, in the first embodiment, the CPU 91 turns off the conversion by the inverter 5 and also converts the converter 10. Control is continued so that the direction of conversion by 1 becomes one direction. Thus, when the battery 3 is connected to the DC input / output terminals T3 and T4 via the relay contacts 31 and 33, the voltage of the capacitor C3 is held at the voltage of the battery 3 and the voltage of the capacitor C3 is converted to the converter. The capacitor C2 is charged to a constant voltage by the DC voltage converted by the 10 in the twelfth direction.

  On the other hand, when the relay contacts 31 and 33 are turned off and the battery 3 is not connected to the DC input / output terminals T3 and T4, the electric power stored in the capacitor C3 is consumed by the converter 10 and the voltage of the capacitor C3 is increased. Since the voltage gradually decreases and the amount of charge to the capacitor C2 gradually decreases, the voltage of the capacitor C2 gradually decreases due to the influence of leakage current and the like.

  Next, when the relay contacts 32 and 33 are turned on and the charging of the capacitor C3 by the battery 3 is started in a state where the voltages of the capacitors C2 and C3 are lowered, the charging flowing into the capacitor C3 through the resistor R1 The voltage of the capacitor C3 gradually increases due to the current. In the first embodiment, since the voltage of the capacitor C3 is always voltage-converted in one direction, the capacitor C2 is gradually charged by the DC voltage obtained by converting the voltage of the capacitor C3. In this way, the inrush current to the capacitors C2 and C3 is suppressed.

  After that, after the voltage of the capacitor C2 becomes higher than the predetermined voltage and the precharge to the capacitors C2 and C3 is considered to be completed, the CPU 91 is based on the charge instruction or the discharge instruction notified from the communication unit 94. However, conversion control of the inverter 5 and the converter 10 by the drive part 97 mentioned above is started.

  In particular, when the discharge instruction is notified, the CPU 91 turns on conversion by the converter 10 to store in the capacitor C2 when the voltage of the capacitor C2 is lower than the predetermined voltage, and stores the second voltage in which the voltage of the capacitor C2 is higher than the predetermined voltage. When the voltage is equal to or higher than the voltage, the conversion by the converter 10 is turned off. Thus, since the voltage of the capacitor C2 is held at a voltage between the predetermined voltage and the second voltage even though the conversion by the converter 10 is intermittently turned on, the AC voltage is changed from the DC voltage by the inverter 5. Conversion to is performed stably.

  Note that intermittently turning on the conversion by the converter 10 is not limited to the above-described case. For example, when the voltage of the capacitor C2 becomes equal to or higher than a second voltage higher than a predetermined voltage after the capacitor C2 is precharged and before the charge instruction or the discharge instruction is notified, the CPU 91 turns off the conversion by the converter 10 Then, after that, when the voltage of the capacitor C3 becomes equal to or lower than the predetermined voltage, the conversion by the converter 10 may be turned on. Also in this case, the power consumption in the converter 10 and the processing load of the CPU 91 that drives the converter 10 are reduced.

Below, operation | movement of the control part 9 mentioned above is demonstrated using the flowchart which shows it. The processing shown below is executed by the CPU 91 according to a computer program 99 stored in advance in the storage unit 92 or the RAM 93. Note that the control program for turning on / off each IGBT by the drive unit 97 by the CPU 91 is known per se, and a description thereof will be omitted.
FIG. 3 is a flowchart showing a processing procedure of the CPU 91 for intermittently turning on the conversion by the converter 10 in the bidirectional AC / DC conversion device 1 according to Embodiment 1 of the present invention. The process of FIG. 3 is activated when the CPU 91 is notified of the start of discharge.

  When the processing of FIG. 3 is started, the CPU 91 turns on the conversion from the DC voltage to the AC voltage (DC / AC conversion) by the inverter 5 by the drive unit 97 (S11), and in one direction by the converter 10. Conversion is temporarily turned off (S12). In this case, the charging of the capacitor C2 stops, whereas the power stored in the capacitor C2 is consumed by the inverter 5 and the external power load, so that the voltage of the capacitor C2 decreases with time. .

  Next, the CPU 91 detects the voltage of the capacitor C2 by the A / D conversion unit 96 (S13), and determines whether or not the detected voltage is lower than a predetermined voltage (for example, 370 V) (S14). When the voltage is not lower than the predetermined voltage (S14: NO), the CPU 91 shifts the process to step S13 in order to repeat the process of detecting the voltage of the capacitor C2 and comparing it with the predetermined voltage.

  When the detected voltage is lower than the predetermined voltage (S14: YES), the CPU 91 turns on the conversion by the converter 10 (S15). Thereby, charging of capacitor C2 by converter 10 is resumed, and the voltage of capacitor C2 starts to rise.

  Next, the CPU 91 detects the voltage of the capacitor C2 by the A / D converter 96 (S16), and determines whether or not the detected voltage is equal to or higher than a second voltage (for example, 420V) higher than a predetermined voltage (S17). ). When the voltage is not equal to or higher than the second voltage (S17: NO), the CPU 91 shifts the process to step S16 in order to repeat the process of detecting the voltage of the capacitor C2 and comparing it with the second voltage.

  When the detected voltage is equal to or higher than the second voltage (S17: YES), the CPU 91 turns off the conversion by the converter 10 (S18). As a result, the charging of the capacitor C2 is stopped and the voltage of the capacitor C2 starts to decrease.

  Thereafter, the CPU 91 determines whether or not an end instruction is notified from the communication unit 94 (S19), and when the end instruction is not notified (S19: NO), the process of turning on / off conversion by the converter 10 is repeated. Therefore, the process proceeds to step S13. When the end instruction is notified (S19: YES), the CPU 91 ends the process of FIG.

Here, the voltage of the capacitor C2 when the processing from steps S13 to S19 in FIG. 3 is repeated will be described.
FIG. 4 is a waveform diagram showing the time change of the voltage of the capacitor C2 when the conversion by the converter 10 is intermittently turned on. In the figure, the horizontal axis represents time, and the vertical axis represents the voltage (V) of the capacitor C2.

  When the conversion by the converter 10 is turned off, the voltage of the capacitor C2 decreases. When the voltage of the capacitor C2 becomes lower than, for example, 370 V (predetermined voltage) at each of the times t1, t3, and t5, the conversion by the converter 10 is performed. The capacitor C2 is charged and the voltage of the capacitor C2 rises quickly.

  After that, when the voltage of the capacitor C2 becomes 420 V (second voltage) or more at each of the times t2, t4, and t6, the conversion by the converter 10 is turned off, the charging to the capacitor C2 is stopped, and the capacitor C2 The voltage gradually decreases. The time from normal time t1 to t2 is sufficiently shorter than the time from time t1 to t3.

  Thus, by repeating the on / off of the conversion by the converter 10, the voltage waveform of the capacitor C2 has a sawtooth shape. When an external power load is not connected to the AC output terminals T5 and T6, the period of the sawtooth wave (for example, from time t1 to t3 or from time t3 to t5) is about 5 seconds to 10 seconds. When an external power load is connected to the AC output terminals T5 and T6, the period of the sawtooth wave changes to short / long depending on the magnitude of the power load.

As described above, according to the first embodiment, the DC voltage obtained by converter 10 converting the DC voltage from battery 3 in one direction is smoothed by capacitor C2 and applied to inverter 5, and this DC voltage is applied to inverter 5. The AC voltage converted by 5 is supplied to the outside from AC output terminals T5 and T6. Further, the DC voltage obtained by converting the AC voltage from the AC power source 2 by the inverter 5 is smoothed by the capacitor and applied to the converter 10, and the DC voltage obtained by converting the DC voltage in the other direction by the converter 10 is smoothed by the capacitor C3. And supplied to the external battery 3. When the conversion by the converter 10 is performed in the one direction and the entire apparatus performs DC / AC conversion, the conversion by the converter 10 is turned on when the voltage of the capacitor C2 is lower than a predetermined voltage.
Thus, the conversion by converter 10 is turned off until the power stored in capacitor C2 is consumed by inverter 5 and the external power load, and the voltage of capacitor C2 drops below a predetermined voltage.
Therefore, when DC / AC conversion is performed, it is possible to reduce the power consumption of the converter 10 and the processing load of the drive circuit.

Further, according to the first embodiment, when the conversion by the converter 10 is turned on, the conversion by the converter 10 is turned off when the voltage of the capacitor C2 becomes equal to or higher than the second voltage higher than the predetermined voltage.
Thereby, the relationship between the voltage of the capacitor C2 and the on / off of the conversion by the converter 10 has a hysteresis characteristic.
Accordingly, it is possible to appropriately secure the on-time and off-time of conversion by the converter 10 and to maintain the voltage of the capacitor C2 at a voltage between the predetermined voltage and the second voltage. In addition, it is possible to prevent the converter 10 from repeating on / off irregularly due to noise superimposed on the voltage of the capacitor C3.

Furthermore, according to the first embodiment, converter 10 includes inverters 6 and 8 that convert a DC voltage and an AC voltage bidirectionally, and a transformer 7 that interconnects them, and inverter 6 (or An AC voltage converted from a DC voltage by the inverter 8) is applied to the primary side (or secondary side) of the transformer 7, and the AC voltage from the secondary side (or primary side) of the transformer 7 is converted to the inverter 8 (or Inverter 6) converts to a DC voltage.
Therefore, it is possible to unify the circuit portion for converting the voltage in the apparatus into a bidirectional inverter, simplify the circuit configuration, and share the drive control.

(Embodiment 2)
The first embodiment is a mode in which the conversion by the converter 10 is turned on (or turned off) when the voltage of the capacitor C2 becomes lower than the predetermined voltage (or becomes equal to or higher than the second voltage), whereas In the second embodiment, the conversion by the converter 10 is turned on when the voltage of the capacitor C3 becomes lower than a predetermined voltage, and the conversion by the converter 10 is turned off after a predetermined time has passed.

Since the configuration of the entire apparatus and the configuration of the control unit 9 in the second embodiment are the same as those in the first embodiment, description thereof is omitted.
FIG. 5 is a flowchart showing a processing procedure of the CPU 91 for intermittently turning on the conversion by the converter 10 in the bidirectional AC / DC conversion apparatus 1 according to Embodiment 2 of the present invention.

The processing from step S21 to S25 and the processing from step S28 to S29 shown in FIG. 5 are the same as the processing from step S11 to S15 and the processing from step S18 to S19 shown in FIG. Therefore, description of processing in these steps is omitted.
In addition, the same code | symbol is attached | subjected to the location corresponding to Embodiment 1, and the description is abbreviate | omitted.

  When the process of step S25 is completed in FIG. 5, the CPU 91 starts measuring time by the timer 95 (S26), and then the timer 95 is set to a predetermined time (for example, when the capacitance value of the capacitor C2 is 1 mF, the predetermined time is several hundreds. It is determined whether or not the time is measured (S27) (S27), and when the predetermined time is not measured (S27: NO), it waits until the predetermined time is measured. As described above, the description of the processing after step S28 executed by the CPU 91 when the predetermined time is measured (S27: YES) is omitted.

  By repeating the ON / OFF of the conversion by the converter 10 by the processing of FIG. 5, the voltage waveform of the capacitor C2 becomes a sawtooth shape similar to that shown in FIG. When an external power load is not connected to the AC output terminals T5 and T6, when the on time of conversion by the converter 10 is substantially the same as the time from time t1 to time t2 shown in FIG. The period is about 5 to 10 seconds. When an external power load is connected to the AC output terminals T5 and T6, the period of the sawtooth wave changes to short / long depending on the magnitude of the power load.

As described above, according to the second embodiment, when the conversion by the converter 10 is turned on, the time measurement by the timer 95 is started, and when the timer 95 measures the predetermined time, the conversion by the converter 10 is turned off. To do.
Therefore, the on-time of conversion by the converter 10 can be made constant, and the off-time can be appropriately controlled according to the magnitude of the alternating current supplied to the external power load.

  The embodiment disclosed this time is to 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. In addition, the technical features described in each embodiment can be combined with each other.

DESCRIPTION OF SYMBOLS 1 Bidirectional AC / DC converter T1, T2 AC input terminal T3, T4 DC input / output terminal T5, T6 AC output terminal 2 AC power source 3 Battery 31, 32, 33 Relay contact 4 Noise filter 5 Inverter 51, 52, 53, 54 IGBT
55, 56, 57, 58 Diode T51, T52 AC input / output terminal T53, T54 DC input / output terminal 6 Inverter 61, 62, 63, 64 IGBT
65, 66, 67, 68 Diode T61, T62 DC input / output terminal T63, T64 AC input / output terminal 7 Transformer 8 Inverter 81, 82, 83, 84 IGBT
85, 86, 87, 88 Diode T81, T82 AC input / output terminal T83, T84 DC input / output terminal 9 Control unit 91 CPU
92 storage unit 93 RAM
94 Communication section 95 Timer 96 A / D conversion section 97 Drive section 98 Recording medium 99 Computer program 10 Converter R1 Resistor C1, C2, C3 Capacitor L1, L2, L3 Choke coil

Claims (6)

An inverter that converts AC voltage and DC voltage bidirectionally, a converter that converts DC voltage bidirectionally, and a capacitor that smoothes the DC voltage converted by the inverter and the DC voltage converted by the converter in one direction A bi-directional AC / DC converter comprising: a control unit for controlling on / off of conversion by the converter; and a control unit for controlling the direction of conversion by the inverter and the converter,
The controller is
When the direction of conversion by the converter is the one direction, a detection unit that detects the voltage of the capacitor;
A determination unit that determines whether or not the voltage detected by the detection unit is lower than a predetermined voltage,
A bidirectional AC / DC converter configured to turn on conversion by the converter when it is determined that the determination unit is low. The controller is
A second determination unit that determines whether the voltage detected by the detection unit is equal to or higher than a second voltage higher than the predetermined voltage when the conversion by the converter is turned on;
The bidirectional AC / DC converter according to claim 1, wherein when the second determination unit determines that the voltage is equal to or higher than the second voltage, the conversion by the converter is turned off. The controller is
When the conversion by the converter is turned on, it has a timer that starts timing,
The bidirectional AC / DC converter according to claim 1, wherein when the timer measures a predetermined time, conversion by the converter is turned off. The converter is
Second and third inverters for bidirectionally converting a DC voltage and an AC voltage;
The bidirectional AC / DC converter according to any one of claims 1 to 3, further comprising: a transformer to which the alternating voltages converted by the second and third inverters are applied to the primary side and the secondary side, respectively. . An inverter that converts AC voltage and DC voltage bidirectionally, a converter that converts DC voltage bidirectionally, and a capacitor that smoothes the DC voltage converted by the inverter and the DC voltage converted by the converter in one direction And intermittently turning on conversion by the converter in a bi-directional AC / DC conversion apparatus comprising: a control unit for controlling on / off of conversion by the converter and a control unit for controlling the direction of conversion by the inverter and converter. Conversion method,
The controller is
When the direction of conversion by the converter is the one direction, detecting the voltage of the capacitor;
Determining whether the voltage detected in the step is lower than a predetermined voltage;
If it is determined that the step is low, turning on conversion by the converter;
If the conversion is turned on in the step, detecting the voltage of the capacitor;
Determining whether the voltage detected in the step is equal to or higher than a second voltage higher than the predetermined voltage;
And a step of turning off conversion by the converter when it is determined that the voltage is equal to or higher than the second voltage in the step. An inverter that converts AC voltage and DC voltage bidirectionally, a converter that converts DC voltage bidirectionally, and a capacitor that smoothes the DC voltage converted by the inverter and the DC voltage converted by the converter in one direction And a control unit for controlling on / off of conversion by the converter and a control unit for controlling the direction of conversion by the inverter and the converter, the conversion by the converter in the bidirectional AC / DC conversion device constitutes the control unit A computer program for turning on a computer intermittently,
On the computer,
When the direction of conversion by the converter is the one direction, detecting the voltage of the capacitor;
Determining whether the voltage detected in the step is lower than a predetermined voltage;
If it is determined that the step is low, the step of turning on the conversion by the converter; and the step of detecting the voltage of the capacitor if the conversion is turned on in the step;
Determining whether the voltage detected in the step is equal to or higher than a second voltage higher than the predetermined voltage;
A computer program that executes a step of turning off conversion by the converter when it is determined in the step that the voltage is equal to or higher than a second voltage.

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