JP2011050227A - Bidirectional converter and electric vehicle controller using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a reduction in the cost of a bidirectional converter. <P>SOLUTION: The bidirectional converter 44 includes a transformer 53 between a first switching circuit 50 and a second switching circuit 51. The transformer 53 has a primary coil 54 closer to the first switching circuit 50 and a secondary coil 55 closer to the second switching circuit 51. The secondary coil 55 has a center tap 56. A switching element S5 is disposed between the center tap 56 and a positive electrode line 64, and a switching element S6 is disposed between both ends 67 and 69 of the secondary coil 55 and the positive electrode line 64. When the element S5 is opened and the element S6 is closed, current flows through the entire part of the secondary coil 55. Alternatively, when the element S5 is closed and the element S6 is opened, current flows through the half of the secondary coil 55. Thereby, the number of coil turns of the transformer 53 is changed, and the bidirectional converter 44 is configured as a simple structure that dispenses with a step-up circuit or step-down circuit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a bidirectional converter that operates between a forward power transmission state and a reverse power transmission state, and an electric vehicle control device using the same.

  Bidirectional converters have been developed that operate in a forward power transmission state in which power is transmitted while converting voltage from one to the other and in a reverse power transmission state in which power is transmitted while converting voltage from the other to the other. As an apparatus to which the bidirectional converter is applied, there is an electric vehicle including a high voltage system and a low voltage system. An electric vehicle has a high-voltage battery (high-voltage system) that supplies power to a drive system, a low-voltage battery (low-voltage system) that supplies power to a control system, and a charging port (low voltage) to which a commercial power supply (for example, AC 200 V) is connected. Voltage system). Such an electric vehicle incorporates a bidirectional converter, and power is supplied from the high voltage battery to the low voltage battery via the bidirectional converter, and the high voltage is supplied from the charging port (commercial power supply) via the bidirectional converter. Power is being supplied to the battery. In addition, as a bidirectional converter installed in hybrid electric vehicles, a function to supply power from a high voltage battery to a low voltage battery and a motor generator (high voltage system) from a low voltage battery when the high voltage battery is depleted There has been proposed a bidirectional converter having a function of supplying power to (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 11-8910

  By the way, when a power is supplied from a high voltage system to a low voltage system, and when a power is supplied from a low voltage system to a high voltage system, the transformation ratio required for the transformer in the bidirectional converter is often different. As shown in Patent Document 1, it is necessary to incorporate a step-up circuit and a step-down circuit separately from the transformer. However, separately installing a booster circuit or a step-down circuit causes a complicated circuit configuration, which has been a factor that hinders cost reduction of the bidirectional converter. Furthermore, it has been a factor that hinders cost reduction of a control device for an electric vehicle in which a bidirectional converter is incorporated.

  An object of the present invention is to achieve cost reduction of a bidirectional converter and a control device for an electric vehicle using the bidirectional converter.

  The bidirectional converter of the present invention operates in a forward power transmission state in which power is transmitted from the first switching circuit to the second switching circuit and in a reverse power transmission state in which power is transmitted from the second switching circuit to the first switching circuit. A bidirectional converter comprising a transformer in which a first coil connected to the first switching circuit and a second coil connected to the second switching circuit and including a center tap are magnetically coupled; The second switching circuit is switched between a full-coil energization state where energization is performed at both ends of the second coil and a half-coil energization state where energization is performed between one end of the second coil and the center tap. .

  In the bidirectional converter according to the present invention, the second switching circuit includes a first switch means provided between the center tap and the positive line, and a second switch provided between both ends of the second coil and the positive line. And switching the second switching circuit to an all-coil energized state by opening the first switch means and connecting the second switch means, while connecting the first switch means. The second switching circuit is opened to switch the second switching circuit to a half-coil energized state.

  An electric vehicle control apparatus according to the present invention is an electric vehicle including a high voltage battery that supplies electric power to a traveling motor, a low voltage battery that supplies electric power to a control system, and a power supply connection unit to which a commercial power supply is connected. A control device comprising the bidirectional converter according to claim 1, wherein the high-voltage battery is connected to the first switching circuit, and the low-voltage battery and the power supply connection unit are connected to the second switching circuit. Connecting and controlling the bidirectional converter to a forward power transmission state, charging the low voltage battery with the high voltage battery, while controlling the bidirectional converter to a reverse power transmission state, thereby connecting the power supply The high voltage battery is charged by a commercial power source connected to the unit.

  The control device for an electric vehicle according to the present invention is characterized in that when the bidirectional converter is controlled to a forward power transmission state, the second switching circuit is switched to an all-coil energization state.

  The control device for an electric vehicle according to the present invention is characterized in that when the bidirectional converter is controlled to be in a reverse power transmission state, the second switching circuit is switched to a half-coil energization state.

  According to the bidirectional converter of the present invention, since the second switching circuit is switched between the full-coil energization state and the half-coil energization state, the turn ratio between the first coil and the second coil can be switched. . Thereby, since the transformer transformation ratio can be switched, it is possible to reduce the step-up circuit and the step-down circuit, and it is possible to reduce the cost of the bidirectional converter.

  According to the control apparatus for an electric vehicle of the present invention, since the bidirectional converter capable of switching the transformation ratio is incorporated, power is supplied from the high voltage battery to the low voltage battery using one bidirectional converter. It becomes possible to supply power to the high voltage battery from the commercial power source. This makes it possible to share a DC / DC converter that supplies power from a high-voltage battery to a low-voltage battery and an in-vehicle charger that supplies power to a high-voltage battery from a commercial power source. Cost reduction can be achieved.

It is the schematic which shows the structure of an electric vehicle. It is the schematic which shows the structure of a power conversion unit. It is a circuit diagram which shows the structure of a bidirectional | two-way converter. (A) And (B) is a timing chart which shows operation | movement of a switching element. (A) And (B) is a circuit diagram which shows the electricity supply path of a bidirectional | two-way converter in a forward direction power transmission state. (A) And (B) is a circuit diagram which shows the electricity supply path of a bidirectional | two-way converter in a reverse direction power transmission state. (A) is explanatory drawing which shows the transformation condition at the time of forward power transmission, (B) is explanatory drawing which shows the transformation status at the time of reverse power transmission. It is the schematic which shows the structure of the conventional electric vehicle. It is the schematic which shows the structure of a DC / DC converter and a vehicle-mounted charger.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of the electric vehicle 10. The electric vehicle 10 is applied with an electric vehicle control apparatus according to an embodiment of the present invention. As shown in FIG. 1, the electric vehicle 10 has a traveling motor 11. A driving shaft 13 is connected to the traveling motor 11 via a gear train 12, and wheels 14 are connected to the driving shaft 13. Further, the electric vehicle 10 is provided with a high voltage battery 15 that functions as a power source for the traveling motor 11. As the high voltage battery 15, for example, a lithium ion secondary battery having a voltage control range of 280V to 380V is used.

  An inverter 20 is connected to the traveling motor 11, and a high voltage battery 15 is connected to the inverter 20 via current-carrying cables 21 and 22. When the traveling motor 11 is driven as an electric motor, the inverter 20 converts a direct current from the high voltage battery 15 into an alternating current, and this alternating current is supplied to the traveling motor 11. On the other hand, when the traveling motor 11 is driven as a generator, the inverter 20 converts the alternating current from the traveling motor 11 into a direct current, and this direct current is supplied to the high voltage battery 15. A main relay 23 is provided in the energization cables 21 and 22 connected to the high voltage battery 15.

  A low voltage battery 25 is connected to the high voltage battery 15 via a power conversion unit 24. As the low voltage battery 25, for example, a lead storage battery having a voltage control range of 10V to 14V is used. The low voltage battery 25 functions as a power source for the inverter 20, the power conversion unit 24, and various control units 30 and 31 described later, and also functions as a power source for air conditioners and headlights (not shown). In this way, power is supplied from the low-voltage battery 25 to the control system and accessories of the electric vehicle 10. The power conversion unit 24 has a function of a DC / DC converter and can supply power from the high voltage battery 15 to the low voltage battery 25 via the power conversion unit 24.

  Further, in order to control the electric vehicle 10 in an integrated manner, the electric vehicle 10 is provided with a vehicle control unit 30. Various vehicle information is input to the vehicle control unit 30, and the vehicle control unit 30 outputs a control signal to the power conversion unit 24, the inverter 20, and the like based on the vehicle information. In addition, in order to control charging / discharging of the high-voltage battery 15, the electric vehicle 10 is provided with a battery control unit (BCU) 31. The battery control unit 31 controls the voltage and current of the high voltage battery 15 and calculates the state of charge SOC of the high voltage battery 15 based on the voltage, current, temperature, and the like. Further, a communication network 32 is built in the electric vehicle 10, and the vehicle control unit 30, the battery control unit 31, the power conversion unit 24, the inverter 20, and the like are connected to each other via the communication network 32. .

  Moreover, in order to charge the high voltage battery 15 using the commercial power source 33 (for example, AC200V), the electric vehicle 10 is provided with a charging port 34 as a power source connecting portion. The charging port 34 includes a connection terminal 35, and the connection terminal 35 is connected to the power conversion unit 24. Furthermore, a connector 37 is provided on the charging cable 36 used by being connected to the commercial power supply 33, and a connecting terminal 38 corresponding to the connecting terminal 35 of the charging port 34 is provided on the connector 37. Then, by connecting the connector 37 to the charging port 34, it is possible to supply power from the commercial power supply 33 to the high voltage battery 15 via the power conversion unit 24. That is, the power conversion unit 24 has not only a function as a DC / DC converter but also a function as an in-vehicle charger. When the high voltage battery 15 is charged from the commercial power supply 33, the low voltage battery 25 is also charged via the power conversion unit 24.

  Hereinafter, the configuration of the power conversion unit 24 will be described. FIG. 2 is a schematic diagram showing the configuration of the power conversion unit 24. As shown in FIG. 2, the power conversion unit 24 includes an AC power source to which a high voltage unit 40 to which a high voltage battery 15 is connected, a low voltage unit 41 to which a low voltage battery 25 is connected, and a charging port 34 are connected. Part 42. An insulation type power factor correction circuit (insulation PFC) 43 is provided between the low voltage part 41 and the AC power supply part 42. The alternating current from the commercial power supply 33 input to the alternating current power supply unit 42 is converted into a direct current corresponding to the low voltage unit 41 via the power factor correction circuit 43. Further, a bidirectional converter 44 according to an embodiment of the present invention is provided between the high voltage unit 40 and the low voltage unit 41. The bidirectional converter 44 has a function of boosting the direct current of the low voltage unit 41, and can transmit power from the low voltage unit 41 to the high voltage unit 40 via the bidirectional converter 44. . Further, the bidirectional converter 44 has a function of stepping down the direct current of the high voltage unit 40, and power can be sent from the high voltage unit 40 to the low voltage unit 41 via the bidirectional converter 44. Yes. The bidirectional converter 44 is a forward type converter.

  Thus, since the power conversion unit 24 includes the power factor correction circuit 43 and the bidirectional converter 44, power can be supplied from the AC power supply unit 42 to the high voltage unit 40 via the low voltage unit 41. The high voltage battery 15 can be charged using the commercial power source 33. In addition, since the power conversion unit 24 includes the bidirectional converter 44, power can be supplied from the high voltage unit 40 to the low voltage unit 41, and the high voltage battery 15 can be used to charge the low voltage battery 25. It becomes possible. Furthermore, since the power conversion unit 24 is configured to sandwich the low voltage unit 41 between the high voltage unit 40 and the AC power supply unit 42, power is supplied from the low voltage unit 41 to the high voltage unit 40 in an emergency. It becomes possible to do. For example, even when the power of the high voltage battery 15 is depleted, the traveling motor 11 can be urgently moved using the power of the low voltage battery 25, and the electric vehicle 10 is moved to a safe place. Is possible. Further, when the power of the high voltage battery 15 is exhausted, the high voltage battery 15 can be charged by a power source (for example, an alternator of another vehicle) connected to the low voltage system of the low voltage battery 25.

  The low voltage unit 41 of the power conversion unit 24 includes a drive circuit 45 that generates a drive signal for the bidirectional converter 44, a drive circuit 46 that generates a drive signal for the power factor correction circuit 43, and these drive circuits 45 and 46. A CPU 47 is provided for calculating a control signal for. Further, the low voltage unit 41 is provided with flyback control power supply units 48 and 49 that function as control power supplies for the CPU 47 and the drive circuits 45 and 46. As described above, by consolidating the control system circuit of the power conversion unit 24 into the low voltage unit 41, simplification and cost reduction of the control system circuit are achieved. One control power supply unit 48 uses power from the high voltage unit 40 as a control power supply, and the other control power supply unit 49 uses power from the AC power supply unit 42 as a control power supply. As a result, even when the power of the high voltage battery 15 is depleted, the power conversion unit 24 can be operated by connecting the charging cable 36 to the charging port 34, and the commercial power source 33 can switch to the high voltage battery 15. In contrast, it is possible to reliably supply power.

  FIG. 3 is a circuit diagram showing a configuration of the bidirectional converter 44. As shown in FIG. 3, the bidirectional converter 44 is connected to the first switching circuit 50 connected to the high voltage unit 40 of the power conversion unit 24, the low voltage unit 41 and the AC power supply unit 42 of the power conversion unit 24. Second switching circuit 51. A transformer 53 is provided between the first switching circuit 50 and the second switching circuit 51, and the transformer 53 includes a primary coil 54 as a first coil connected to the first switching circuit 50, And a secondary coil 55 as a second coil connected to the second switching circuit 51. The primary coil 54 and the secondary coil 55 are wound around a common magnetic circuit and magnetically coupled. The secondary coil 55 is provided with a center tap 56.

  The first switching circuit 50 has four switching elements S1 to S4. As these switching elements S1 to S4, transistors, IGBTs, MOSFETs or the like are used. The switching element S1 on the positive electrode line 60 side and the switching element S2 on the negative electrode line 61 side are connected in series, and the connection point between the elements S1 and S2 is connected to one end 62 of the primary coil 54. The switching element S3 on the positive electrode line 60 side and the switching element S4 on the negative electrode line 61 side are connected in series, and the connection point of the elements S3 and S4 is connected to the other end 63 of the primary coil 54.

  The second switching circuit 51 has four switching elements S5 to S8. As these switching elements S5 to S8, transistors, IGBTs, MOSFETs or the like are used. The switching element (first switch means) S5 on the positive electrode line 64 side is connected to the center tap 56 of the secondary coil 55. The switching element (second switch means) S6 on the positive electrode line 64 side is connected in series to the switching element S7 on the negative electrode line 66 side via a rectifying element 65. A connection point between the rectifying element 65 and the switching element S 7 is connected to one end 67 of the secondary coil 55. Further, the switching element S6 on the positive electrode line 64 side is connected in series to the switching element S8 on the negative electrode line 66 side through the rectifying element 68. A connection point between the rectifying element 68 and the switching element S8 is connected to the other end 69 of the secondary coil 55.

  Here, FIGS. 4A and 4B are timing charts showing operations of the switching elements S1 to S8. 4A shows a forward power transmission state in which power is supplied from the first switching circuit 50 on the high voltage unit 40 side to the second switching circuit 51 on the low voltage unit 41 side, and FIG. A reverse power transmission state in which power is supplied from the second switching circuit 51 on the low voltage unit 41 side to the first switching circuit 50 on the high voltage unit 40 side is shown. Note that, in FIGS. 4A and 4B, the filled portions indicate the ON state of the switching element. 5A and 5B are circuit diagrams showing energization paths of the bidirectional converter 44 in the forward power transmission state. FIGS. 6A and 6B are circuit diagrams showing energization paths of the bidirectional converter 44 in the reverse power transmission state.

  As shown in FIG. 4A, when the bidirectional converter 44 transmits power in the forward direction, the first switching circuit 50 controls the switching elements S1 and S4 to the on state and controls the switching elements S2 and S3 to the off state. The first mode and the second mode in which the switching elements S1, S4 are controlled to be turned off and the switching elements S2, S3 are controlled to be turned on are alternately repeated at a predetermined cycle. Further, in the second switching circuit 51, the switching element S7 is controlled to be turned on so as to be synchronized with the first and second modes of the first switching circuit 50 while the switching element S6 is kept on. A first mode for controlling the element S8 to be turned off and a second mode for controlling the switching element S7 to be turned off and controlling the switching element S8 to be turned on are alternately repeated at a predetermined cycle. As shown in FIG. 4A, during forward power transmission, switching control is performed by combining the synchronous rectification method and the phase shift method.

  In this way, by controlling the first and second switching circuits 50 and 51, the energization states shown in FIGS. 5A and 5B are alternately repeated, and the first switching circuit is caused by the electromagnetic induction action of the transformer 53. Power is supplied from 50 to the second switching circuit 51. At this time, since the switching element S6 is held in the on state, the switching elements S7 and S8 are alternately turned on / off, thereby energizing both ends 67 and 69 of the secondary coil 55. That is, by switching the switching element S5 to the off state (open state) and switching the switching element S6 to the on state (connected state), the second switching circuit 51 is switched to the full coil energized state that energizes the entire secondary coil 55. Will be switched.

  Further, as shown in FIG. 4B, when the bidirectional converter 44 transmits power in the reverse direction, the second switching circuit 51 controls the switching element S7 to be on while keeping the switching element S5 on. The first mode for controlling the switching element S8 to be turned off and the second mode for controlling the switching element S7 to be turned off and controlling the switching element S8 to be turned on are alternately repeated at a predetermined cycle. In the first switching circuit 50, the switching elements S1 and S4 are controlled to be in an on state and the switching elements S2 and S3 are controlled to be in an off state so as to be synchronized with the first and second modes of the second switching circuit 51. And the second mode in which the switching elements S1 and S4 are controlled to be turned off and the switching elements S2 and S3 are controlled to be turned on are alternately repeated at a predetermined cycle. As shown in FIG. 4B, switching control is performed using a synchronous rectification method during reverse power transmission.

  As described above, by controlling the first and second switching circuits 50 and 51, the energization state shown in FIGS. 6A and 6B is alternately repeated, and the second switching circuit is caused by the electromagnetic induction action of the transformer 53. Power is supplied from 51 to the first switching circuit 50. At this time, since the switching element S5 is held in the on state, the switching elements S7 and S8 are alternately turned on / off so that the one end 67, 69 of the secondary coil 55 and the center tap 56 are energized. It has become. That is, by switching the switching element S5 to the on state and switching the switching element S6 to the off state, the second switching circuit 51 is switched to the half-coil energized state in which half of the secondary coil 55 is energized.

  As described above, the second switching circuit 51 is switched to the full coil energized state during forward power transmission, while the second switching circuit 51 is switched to the half coil energized state during reverse power transmission. Thus, by switching between the full-coil energized state and the half-coil energized state, the turns ratio of the primary coil 54 and the secondary coil 55 can be switched. Thereby, since the transformer ratio of the transformer 53 can be switched, while using the transformer 53 including the pair of coils 54 and 55, the transformer ratio when supplying power from the high voltage unit 40 to the low voltage unit 41, It is possible to change the transformation ratio when power is supplied from the low voltage unit 41 to the high voltage unit 40.

  Here, the voltage fluctuation range of the high voltage unit 40 to which the high voltage battery 15 is connected is 280V to 400V, and the voltage fluctuation range of the low voltage unit 41 to which the low voltage battery 25 is connected is 10V to 14V. For this reason, when power is supplied from the high voltage unit 40 to the low voltage unit 41, the ability to transform the voltage from the low voltage level of 280V of the high voltage unit 40 to 14V which is the high voltage level of the low voltage unit 41 is provided. This is required for the bidirectional converter 44. On the other hand, when power is supplied from the low voltage unit 41 to the high voltage unit 40, the transformation capability of boosting from 10V, which is the low voltage level of the low voltage unit 41, to 400V, which is the high voltage level of the high voltage unit 40, This is required for the bidirectional converter 44.

  Thus, the transformation ratio required for the transformer 53 when controlling the bidirectional converter 44 to the forward power transmission state, and the request for the transformer 53 when controlling the bidirectional converter 44 to the reverse power transmission state. Therefore, it has been necessary to take measures such as constructing a transformer in accordance with any one of the transformation ratios and incorporating a step-up circuit or a step-down circuit separately. On the other hand, in the bidirectional converter 44 of the present invention, it is possible to switch the transformation ratio of the transformer 53 by switching the second switching circuit 51 between the full coil energized state and the half coil energized state. As a result, the step-up circuit and the step-down circuit can be reduced, so that the circuit configuration of the bidirectional converter 44 can be simplified.

  FIG. 7 (A) is an explanatory diagram showing a transformation state during forward power transmission, and FIG. 7 (B) is an explanatory diagram showing a transformation situation during reverse power transmission. First, as shown in FIG. 7A, in the illustrated transformer 53, the number of turns of the primary coil 54 is 40, and the number of turns of the secondary coil 55 is 2. At the time of forward power transmission in which power is supplied from the high voltage unit 40 to the low voltage unit 41, the second switching circuit 51 is switched to the all-coil energization state, so that the turns ratio of the transformer 53 is set to 40: 2. As a result, when the voltage level of the high voltage unit 40 is 280V, the voltage can be reduced to 14V via the transformer 53. On the other hand, as shown in FIG. 7B, the second switching circuit 51 is switched to the half-coil energized state at the time of reverse power transmission in which power is supplied from the low voltage unit 41 to the high voltage unit 40. The ratio is set to 40: 1. As a result, when the voltage level of the low voltage unit 41 is 10V, the voltage can be raised to 400V via the transformer 53.

The output voltage _{V out} which is obtained through the transformer 53, as shown in the following equation (1), not only determined by the input voltage _{V in} and the turns ratio m, the switching elements S1 to S4, S7, It is determined by the duty ratio D when driving S8. Therefore, when the power transmission using a bi-directional converter 44, after switching the turns ratio m of the transformer 53 in accordance with the transmission direction, in accordance with the input voltage V _in to the output voltage Vout necessary to obtain The duty ratio D is adjusted.
V _out = m × D × V _in (1)

  As described so far, in the bidirectional converter 44 of the present invention, the transformer ratio of the transformer 53 is switched by switching the energization state of the secondary coil 55. As a result, even when a plurality of output voltage levels are required, the step-up circuit and the step-down circuit can be omitted from the bidirectional converter 44, so that the cost of the bidirectional converter 44 can be reduced. . Further, by incorporating the bidirectional converter 44 capable of switching the transformation ratio into the control device of the electric vehicle, power can be supplied from the high voltage battery 15 to the low voltage battery 25 without incorporating a plurality of power conversion devices. It is possible to supply power from the commercial power supply 33 to the high voltage battery 15. That is, in the conventional control apparatus for an electric vehicle, a DC / DC converter for supplying power from the high voltage battery 15 to the low voltage battery 25 and an in-vehicle system for supplying power from the commercial power source 33 to the high voltage battery 15. Although the battery charger is provided, in the electric vehicle control device of the present invention, the DC / DC converter and the vehicle-mounted charger can be shared.

  Here, FIG. 8 is a schematic diagram showing a configuration of a conventional electric vehicle 100, and FIG. 9 is a schematic diagram showing a configuration of a DC / DC converter 101 and an in-vehicle charger 102. In FIG. 8, members similar to those shown in FIG. 2 are given the same reference numerals and description thereof is omitted. As shown in FIG. 8, a DC / DC converter 101 is provided between the high voltage battery 15 and the low voltage battery 25 in order to charge the low voltage battery 25 from the high voltage battery 15. Further, an in-vehicle charger 102 is provided between the charging port 34 and the high voltage battery 15 in order to supply power from the commercial power source 33 to the high voltage battery 15. As shown in FIG. 9, the DC / DC converter 101 is provided with a step-down forward converter 103, a CPU 104 that calculates a control signal, a control power supply unit 105 that functions as a control power supply for the forward converter 103, and the like. The in-vehicle charger 102 includes a power factor correction circuit 106 that converts alternating current into direct current, a forward converter 107 for the high voltage battery 15, a flyback converter 108 for the low voltage battery 25, and a CPU 109 that calculates control signals. Further, a control power supply unit 110 or the like that functions as a control power supply for the forward converter 107 or the like is provided.

  As described above, the DC / DC converter 101 and the in-vehicle charger 102 are configured by a large number of components and circuits. However, in the electric vehicle control device of the present invention, the DC / DC converter 101 and the in-vehicle charger 102 are shared. Can be achieved. As a result, as shown in FIG. 2, reduction of duplicate circuit parts (power parts, protective elements, etc.), reduction of structural parts (housing, covers, bolts, cooling structural parts, etc.), peripheral parts (harnesses, brackets, etc.) This makes it possible to significantly reduce the manufacturing cost and development cost of the control device for an electric vehicle.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. In the above description, the bidirectional converter 44 of the present invention is applied to a control device for an electric vehicle. However, the present invention is not limited to this, and the bidirectional converter 44 of the present invention is applied to other electric devices. May be. Further, the electric vehicle 10 shown in the figure is an electric vehicle having only the traveling motor 11 as a driving source, but may be a hybrid electric vehicle having the traveling motor 11 and an engine as driving sources. Furthermore, although the charging port 34 is provided as a power supply connection portion in the illustrated electric vehicle 10, a charging cable as a power supply connection portion may be provided on the electric vehicle 10 side. Further, the electric vehicle 10 shown in the figure is provided with a charging port 34 for connecting a charging cable 36 extending from a commercial power source 33 (for example, AC 200V). In addition to the charging port 34, a charging port for quick charging is provided. May be provided. In this case, the charging port for quick charging is connected to the high voltage unit 40 of the power conversion unit 24.

  In the above description, in order to control charging / discharging among the high voltage battery 15, the low voltage battery 25, and the commercial power source 33, the output voltage is reduced during forward power transmission, while the output voltage is increased during reverse power transmission. However, the present invention is not limited to this, and the output voltage may be raised in both directions, or the output voltage may be lowered in both directions. For example, when the number of turns of the primary coil 54 is set to 3 and the number of turns of the secondary coil 55 with the center tap 56 is set to 4, the second switching circuit 51 is switched between the full coil energized state and the half coil energized state. As a result, the magnitude relationship between the number of turns of the primary coil 54 and the number of turns of the secondary coil 55 can be reversed. Thus, by setting the number of turns of the coils 54 and 55, it is possible to increase the output voltage in both directions and decrease the output voltage in both directions.

  In the above description, the second switching circuit 51 is controlled to the full coil energized state during forward power transmission, while the second switching circuit 51 is controlled to the half coil energized state during reverse power transmission. When the bidirectional converter 44 is applied to other electrical devices, the second switching circuit 51 may be controlled in a half-coil energized state during forward power transmission, and the second switching circuit 51 may be fully controlled during reverse power transmission. You may control to a coil energization state. That is, in the forward power transmission state shown in FIG. 5, the switching element S6 may be switched to the OFF state and the switching element S5 may be switched to the ON state. In the reverse power transmission state shown in FIG. The switching element S6 may be switched to the ON state by switching.

DESCRIPTION OF SYMBOLS 10 Electric vehicle 11 Driving motor 15 High voltage battery 25 Low voltage battery 33 Commercial power supply 34 Charging port (power connection part)
44 Bidirectional Converter 50 First Switching Circuit 51 Second Switching Circuit 53 Transformer 54 Primary Coil (First Coil)
55 Secondary coil (second coil)
56 Center tap 64 Positive line S5 Switching element (first switch means)
S6 Switching element (second switch means)

Claims (5)

A bidirectional converter operating in a forward power transmission state in which power is transmitted from the first switching circuit to the second switching circuit and in a reverse power transmission state in which power is transmitted from the second switching circuit to the first switching circuit;
A transformer in which a first coil connected to the first switching circuit and a second coil connected to the second switching circuit and having a center tap are magnetically coupled;
The second switching circuit is switched between a full-coil energization state where energization is performed at both ends of the second coil and a half-coil energization state where energization is performed between one end of the second coil and the center tap. Bidirectional converter. The bidirectional converter according to claim 1, wherein
The second switching circuit includes first switch means provided between the center tap and a positive line, and second switch means provided between both ends of the second coil and the positive line.
While opening the first switch means and connecting the second switch means, the second switching circuit is switched to an all-coil energization state,
A bidirectional converter characterized in that the second switching circuit is switched to a half-coil energized state by connecting the first switch means and opening the second switch means. A control device for an electric vehicle comprising a high-voltage battery that supplies power to a traveling motor, a low-voltage battery that supplies power to a control system, and a power supply connection unit to which a commercial power supply is connected,
A bidirectional converter according to claim 1 or 2,
Connecting the high voltage battery to the first switching circuit, connecting the low voltage battery and the power source connection to the second switching circuit;
While charging the low voltage battery with the high voltage battery by controlling the bidirectional converter to a forward power transmission state,
A control apparatus for an electric vehicle, wherein the high-voltage battery is charged by a commercial power source connected to the power source connection unit by controlling the bidirectional converter to a reverse power transmission state. The control apparatus for an electric vehicle according to claim 3,
When controlling the bidirectional converter to a forward power transmission state, the second switching circuit is switched to an all-coil energization state. In the control apparatus of the electric vehicle according to claim 3 or 4,
When controlling the bidirectional converter to a reverse power transmission state, the second switching circuit is switched to a half-coil energization state.

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