JP2018164338A - Power conversion device, and control system - Google Patents

Abstract

An object of the present invention is to provide a power conversion device and a control system capable of supplying a suitable voltage to a device.
The power converter includes sub-wirings SL1 and SL2 that connect an output side of a first DC / DC converter 30 and an output side of a second DC / DC converter 35. A first device group 60 and a second device group 65 are electrically connected to the sub wirings SL1 and SL2. A load SW 70 is provided between the connection point of the first device group 60 and the connection point of the second device group 65 in the sub wiring. The load SW 70 switches the connection between the first DC / DC converter 30 and the second DC / DC converter 35 in the sub wiring between a conductive state and a cut-off state.
[Selection] Figure 1

Description

  The present invention relates to a power conversion device applied to a power supply system, and a control system including the power conversion device and the power supply system.

  Patent Document 1 discloses a control including a main power storage device, a main power supply wiring that electrically connects the main power storage device and the inverter, and a first DC / DC converter and a second DC / DC converter connected to the main power supply wiring. A system is disclosed. The output sides of the first DC / DC converter and the second DC / DC converter are connected by a common sub-wiring. A plurality of devices are electrically connected to the sub-wiring, and power is supplied to the devices from the first DC / DC converter and the second DC / DC converter through the sub-wiring.

JP, 2006-101057, A

  In the control system described in Patent Document 1, the first end of the sub-wiring is connected to the first DC / DC converter, and the second end is connected to the second DC / DC converter. The voltage applied to the sub wiring is set according to the output voltage of the first DC / DC converter and the output voltage of the second DC / DC converter. Therefore, each device group connected to the sub wiring is supplied with the same voltage.

  If the voltage supplied from the sub-wiring to each device group is the same value, it is not possible to connect each device in parallel to the sub-wiring with different voltages supplied to each device. Accompany. Moreover, when connecting a sub wiring and an apparatus through a transformer device so that it can respond to different voltages, there is a possibility that the size of the control system may be enlarged.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a power conversion device and a control system that can supply a voltage suitable for a device.

  In order to solve the above problem, the power conversion device according to the first invention is applied to a power supply system including a main power storage device and a main supply wiring connected to the main power storage device. The power conversion device is connected to the main supply wiring, and a first DC / DC converter that steps down the output voltage of the main power storage device, and a second DC that is connected to the main supply wiring and steps down the output voltage of the main power storage device. / DC converter, and the sub wiring which connects the output side of said 1st DC / DC converter, and the output side of said 2nd DC / DC converter, and a 1st apparatus and a 2nd apparatus are connected. The sub-wiring is provided between a connection point with the first device and a connection point with the second device, and the output side of the first DC / DC converter and the output side of the second DC / DC converter. And a main switching unit that switches the connection state between the conduction state and the cutoff state through the sub-wiring.

  In the power conversion device configured as described above, the main switching unit cuts off the electrical connection state between the output side of the first DC / DC converter and the output side of the second DC / DC converter from the conductive state. Switch to state. Therefore, the output voltage of the first DC / DC converter is applied to the first device without being applied to the second device. Further, the output voltage from the second DC / DC converter is applied to the second device without being applied to the first device. As a result, it is possible to supply power to the first device and the second device with different output voltages. Thereby, a suitable voltage can be supplied to each of the first device and the second device.

  Here, switching between the conduction state and the cutoff state is performed, for example, as in the second invention, by the main switching unit between the conduction state and the cutoff state between the first DC / DC converter and the second DC / DC converter. This can be implemented by an open / close control unit that controls the switching of these.

  In a third aspect of the invention, a sub power storage device connected to the sub wiring is provided. With the above structure, fluctuations in the voltage value of the sub wiring are suppressed by the voltage applied from the sub power storage device to the sub wiring. Therefore, fluctuations in power supplied to the first device group or the second device group can be suppressed.

  According to a fourth aspect of the present invention, the output voltage of the first DC / DC converter and the second DC / DC converter are made to coincide with each other when the main switching unit switches between the conduction state and the cutoff state. A voltage control unit configured to control an output voltage command value of the first DC / DC converter and an output voltage command value of the second DC / DC converter;

  When the voltage difference between both ends of the main switching unit is large, a current flows through the main switching unit when switching between the conduction state and the cutoff state, which may cause a switching loss. For this reason, in the above configuration, the output voltage of the first DC / DC converter is set so that the output voltages of the first DC / DC converter and the second DC / DC converter coincide with each other when switching between the conductive state and the cutoff state by the main switching unit. The command value and the output voltage command value of the second DC / DC converter are controlled. In this case, the current flowing through the main switching unit can be reduced and switching loss can be suppressed.

  In a fifth aspect of the invention, the power storage device includes: a sub power storage device connected to the sub wiring; and a voltage detection unit that detects a voltage between terminals of the sub power storage device, wherein the voltage control unit includes the first DC / DC converter. The output voltage command value of the first DC / DC converter and the output voltage command value of the second DC / DC converter are controlled so that the respective output voltages of the second DC / DC converter coincide with the detected inter-terminal voltage. To do.

  With the above configuration, the current flowing through the main switching unit can be reduced by controlling the output voltage of the first DC / DC converter and the output voltage of the second DC / DC converter to be the inter-terminal voltage of the sub power storage device. . As a result, switching loss can be suppressed.

  In a sixth aspect of the present invention, the sub-wiring is provided on the first DC / DC converter side of the first device, and the closed state is established between the output side of the first DC / DC converter and the first device. A first device switching unit is provided that is electrically connected and opened to cut off an electrical connection between the output side of the first DC / DC converter and the first device.

  With the above configuration, the electrical connection between the output side of the first DC / DC converter and the first device can be switched. Therefore, for example, when an abnormality occurs in the first DC / DC converter, the first device group can be protected by cutting off the electrical connection between the first DC / DC converter and the first device.

  Here, when the first DC / DC converter fails, the electrical connection between the first DC / DC converter and the first device is interrupted by, for example, the first device controller as in the seventh invention. This can be implemented by controlling the first device switching unit.

  In an eighth aspect of the invention, the sub-wiring is provided on the second DC / DC converter side with respect to the second device, and the closed state is established between the output side of the second DC / DC converter and the second device. A second device switching unit is provided that is electrically connected and opened to cut off an electrical connection between the output side of the second DC / DC converter and the second device.

  With the above configuration, the electrical connection between the output side of the second DC / DC converter and the second device can be switched. Therefore, for example, when an abnormality occurs in the second DC / DC converter, the second device group can be protected by cutting off the electrical connection between the second DC / DC converter and the second device.

  Here, when the second DC / DC converter breaks down, the electrical connection between the second DC / DC converter and the second device is interrupted by, for example, the second device controller as in the ninth invention. This can be implemented by controlling the second device switching unit.

  In a tenth aspect of the invention, an output voltage output from the first DC / DC converter to the first device is a first output voltage, and an output voltage output from the second DC / DC converter to the second device is a second output voltage. The first output voltage is included in a first voltage range in which the power conversion efficiency of the first DC / DC converter is greater than or equal to a predetermined value, and the second output voltage is the second DC / DC The power conversion efficiency of the converter is included in the second voltage range that is equal to or greater than the predetermined value.

  With the above configuration, it is possible to supply appropriate power to each of the first device and the second device in a state where the power conversion efficiency between the first DC / DC converter and the second DC / DC converter is set to a predetermined value or more. As a result, the power conversion device can be operated with high power conversion efficiency.

  Moreover, a control system provided with the power converter device which concerns on this invention, and a power supply system is realizable.

The block diagram of the control system which concerns on 1st Embodiment. The graph explaining the relationship between an output voltage and the power conversion efficiency of each DDC. The flowchart explaining the electric power supply control implemented by HV-ECU. The figure explaining the electric current which flows into each line in the case of precharging a smoothing capacitor. The figure explaining the electric current which flows into each line at the time of supplying electric power to the 1st apparatus group and the 2nd apparatus group. The flowchart explaining the process implemented by HV-ECU in step S19 of FIG. The graph explaining the change of each output voltage V1r, V2r and the 2nd terminal voltage Vb2r. The graph explaining the change of each output voltage V1r, V2r and the 2nd terminal voltage Vb2r. The block diagram of the control system which concerns on 3rd Embodiment. The flowchart explaining the process implemented by HV-ECU in 3rd Embodiment. The graph explaining the change of each output voltage V1r, V2r and the 2nd terminal voltage Vb2r. The block diagram of the control system which concerns on 4th Embodiment. The flowchart explaining the electric power feeding interruption process implemented by HV-ECU.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a control system 100 according to the first embodiment. The control system 100 is mounted on a vehicle. In this embodiment, the vehicle on which the control system 100 is mounted is a hybrid vehicle that includes an engine that is an internal combustion engine and a traveling motor as traveling power sources.

  The control system 100 includes a first storage battery 50 corresponding to a main power storage device, a power control unit (PCU) 40, a first DC / DC converter 30, and a second DC / DC converter 35. Hereinafter, the first DC / DC converter 30 is referred to as a first DDC 30 and the second DC / DC converter 35 is referred to as a second DDC 35. In the first embodiment, the power supply system includes a first storage battery 50 and a PCU 40, and the power converter includes a first DDC 30 and a second DDC 35.

  A first motor 11, a second motor 12, a first device group 60, and a second device group 65 are connected to the control system 100. The control system 100 supplies power to the motors 11 and 12, the first device group 60, and the second device group 65 based on the power supplied from the first storage battery 50.

  The first storage battery 50 functions as a main power source in the control system 100. In the present embodiment, the first storage battery 50 is a lithium ion storage battery. Specifically, the 1st storage battery 50 is an assembled battery which combined the cell of the some lithium ion storage battery, for example, produces the voltage between terminals 200V-400V.

  The PCU 40 converts the power supplied from the first storage battery 50 and supplies power to the motors 11 and 12. The PCU 40 includes a smoothing capacitor 41, a converter 42 that boosts the voltage supplied from the first storage battery 50, and an inverter 43 that converts a DC voltage output from the converter 42 into an AC voltage. The input side of the converter 42 is connected to the first high voltage line HL1 connected to the plus side terminal of the first storage battery 50 and the second high voltage line HL2 connected to the minus side terminal of the first storage battery 50. The smoothing capacitor 41 is connected in parallel to the converter 42 between the first high-voltage line HL1 and the second high-voltage line HL2. The inverter 43 is connected to the output side of the converter 42 on the input side, and is connected to the motors 11 and 12 on the output side.

  Each motor 11, 12 is driven by an AC voltage converted by the inverter 43. In the present embodiment, the first motor 11 is a vehicle driving motor. The first motor 11 has a function of generating regenerative power using the kinetic energy of the vehicle while the vehicle is running. The second motor 12 has a starter function for starting the engine and a power generation function as an alternator. The inverter 43 has a rectifying function for rectifying an alternating current into a direct current. The inverter 43 rectifies the alternating current output from the first motor 11 by regenerative power generation into a direct current during braking of the vehicle. The rectified direct current is supplied to the first storage battery 50 through the high-voltage lines HL1 and HL2, whereby the first storage battery 50 is charged.

  The first high-voltage line HL1 is provided with a first relay SMR1, and the second high-voltage line HL2 is provided with a second relay SMR2. Each relay SMR1, SMR2 is controlled to be in a closed state, whereby the first storage battery 50 and the PCU 40 are electrically connected. Thereby, electric power feeding from the 1st storage battery 50 to PCU40 is attained. On the other hand, the electrical connection between the first storage battery 50 and the PCU 40 is interrupted by controlling the relays SMR1 and SMR2 to the open state.

  The first DDC 30 is a bidirectional buck-boost converter, and includes a first drive unit 31 and a first control unit 32 that controls the operation of the first drive unit 31.

  The first drive unit 31 includes a plurality of semiconductor switches, and performs a step-down operation or a step-up operation on the input voltage by switching each semiconductor switch on and off. The first input / output terminal Tio1 of the first drive unit 31 is connected to a third high voltage line HL3 that is connected to the first high voltage line HL1. The second input / output terminal Tio2 is connected to a fourth high voltage line HL4 that is connected to the second high voltage line HL2. The third input / output terminal Tio3 is connected to the first sub-line SL1, and the fourth input / output terminal Tio4 is connected to the second sub-line SL2.

  In the present embodiment, the third high-voltage line HL3 is connected to the first high-voltage line HL1 on the PCU 40 side with respect to the first relay SMR1. The fourth high voltage line HL4 is connected to the second high voltage line HL2 on the PCU 40 side with respect to the second relay SMR2. Of the sub-wirings SL1 and SL2, the second sub-wiring SL2 is connected to the ground.

  The first control unit 32 drives each semiconductor switch of the first drive unit 31. The first control unit 32 controls the duty ratio, which is the ratio of the on period to one switching cycle of each semiconductor switch, in order to control the output voltage of the first drive unit 31 to the output voltage command value. Hereinafter, the output voltage command value of the first DDC 30 is referred to as a first voltage command value V1 *. The first control unit 32 performs the step-down operation of the first drive unit 31 so that the input voltage supplied to the first input / output terminal Tio1 through the third high-voltage line HL3 is stepped down, and the first input / output terminal Tio3 starts to reduce the first voltage. One sub-line SL1 is supplied. On the other hand, the first control unit 32 boosts the first driving unit 31 to boost the input voltage supplied to the third input / output terminal Tio3 through the first sub-wiring SL1, and the first input / output terminal Tio1 It is supplied to the third high-pressure line HL3.

  The second DDC 35 is a unidirectional step-down converter, and includes a second drive unit 36 that steps down the input voltage, and a second control unit 37 that controls the operation of the second drive unit 36.

  The second drive unit 36 includes a plurality of semiconductor switches, and steps down and outputs the input voltage supplied from the first storage battery 50 by switching each semiconductor switch on and off. The first input terminal Ti1 of the second drive unit 36 is connected to a fifth high voltage line HL5 connected to the first high voltage line HL1. The second input terminal Ti2 is connected to a sixth high voltage line HL6 connected to the second high voltage line HL2. The first output terminal To1 of the second drive unit 36 is connected to the first sub-wiring SL1, and the second output terminal To2 is connected to the second sub-wiring SL2.

  In the present embodiment, the fifth high voltage line HL5 is connected to the first high voltage line HL1 on the first storage battery 50 side with respect to the first relay SMR1. The sixth high voltage line HL6 is connected to the second high voltage line HL2 on the first storage battery 50 side with respect to the second relay SMR2. Therefore, even when each of the relays SMR1, 2 is controlled to be in the open state, the electrical connection between the first storage battery 50 and the second DDC 35 is maintained. In the present embodiment, each of the high voltage lines HL1 to HL6 corresponds to a main supply wiring.

  The second control unit 37 drives each semiconductor switch of the second drive unit 36. The second control unit 37 controls the duty ratio, which is the ratio of the ON period to one switching cycle of each semiconductor switch, in order to control the output voltage of the second drive unit 36 to the output voltage command value. Hereinafter, the output voltage command value of the second DDC 35 is referred to as a second voltage command value V2 *. By controlling the duty ratio by the second control unit 37, the input voltage supplied to the first input terminal Ti1 is stepped down and supplied to the first sub-wiring SL1 through the first output terminal To1.

  A first device group 60 and a second device group 65 that are fed through the sub-wirings SL1 and SL2 are connected to the sub-wirings SL1 and SL2. Each positive terminal of the first device group 60 is connected to the first power supply line SP1 connected to the first sub-line SL1. Each positive terminal of the second device group 65 is connected to the second power supply line SP2 connected to the first sub-line SL1 on the second DDC 35 side with respect to the first power supply line SP1. And the negative electrode side terminal of each apparatus group 60,65 is connected to 3rd electric power feeding wiring SP3 connected to 2nd sub wiring SL2.

  The first device group 60 and the second device group 65 have the same rated voltage, but have different efficiencies depending on the voltages supplied through the sub-wirings SL1 and SL2. In the present embodiment, a voltage range in which the efficiency of the first device group 60 is high is defined as a first voltage range, and a voltage range in which the efficiency of the second device group 65 is high is defined as a second voltage range. The first voltage range is located on the lower voltage side than the second voltage range. In the present embodiment, the maximum value of the first voltage range is lower than the minimum value of the second voltage range. Each of the device groups 60 and 65 is, for example, an audio device, a navigation device, a power slide door, a power back door, and a meter.

  FIG. 2 is a graph for explaining the relationship between the output voltage and the power conversion efficiency of each of the DDCs 30 and 35. In FIG. 2, the horizontal axis represents the output voltage [V] of each DDC 30, 35, and the vertical axis represents the power conversion efficiency [%] of each DDC 30, 35. Among these, RV 1 is the first voltage range of the first device group 60, and RV 2 is the second voltage range of the second device group 65. Moreover, ηt is a target range determined as a range in which the power conversion efficiency is equal to or higher than the efficiency threshold Thη.

  The power conversion efficiency of the first DDC 30 is the target range ηt when the output voltage within the first voltage range RV1 is output. Further, the power conversion efficiency of the second DDC 35 is the target range ηt when outputting the output voltage within the second voltage range RV2.

  Returning to the description of FIG. 1, a load switch 70 (hereinafter referred to as “switching state”) that switches the electrical connection state between the first DDC 30 and the second DDC 35 via the first sub-wiring SL1 between a conductive state and a cut-off state. A load SW 70) is provided. In the present embodiment, the load SW 70 is provided between the connection point of the first power supply line SP1 and the connection point of the second power supply line SP2 in the first sub-line SL1. The load SW 70 is composed of, for example, a pair of N-channel MOSFETs whose sources or drains are connected.

  When the load SW 70 is controlled to be closed, the third input / output terminal Tio3 of the first DDC 30 and the first output terminal To1 of the second DDC 35 are electrically connected via the first sub-wiring SL1. . Further, the load SW 70 is controlled to be in an open state, whereby the electrical connection between the third input / output terminal Tio3 and the first output terminal To1 via the first sub-wiring SL1 is cut off. The load SW 70 corresponds to the main switching unit.

  A second storage battery 55 corresponding to a sub power storage device is connected to each sub wiring SL1, SL2. The positive terminal of the second storage battery 55 is connected to the first sub-wiring SL1, and the negative terminal is connected to the second sub-wiring SL2. In the present embodiment, the positive side terminal and the negative side terminal of the second storage battery 55 are connected to the sub wirings SL1 and SL2 on the first DDC 30 side with respect to the load SW 70. Therefore, at least one of the output voltage of each DDC 30, 35 and the voltage between the terminals of the second storage battery 55 is applied to the first sub-wiring SL1. Below, the voltage between the terminals of the 1st storage battery 50 is described as the 1st terminal voltage Vb1r, and the voltage between the terminals of the 2nd storage battery 55 is described as the 2nd terminal voltage Vb2r.

  In the present embodiment, the storage capacity of the second storage battery 55 is smaller than the storage capacity of the first storage battery 50. The second inter-terminal voltage Vb2r of the second storage battery 55 is lower than the first inter-terminal voltage Vb1r of the first storage battery 50. For example, the terminal voltage of the second storage battery 55 is 12V.

  In addition, the control system 100 includes an HV-ECU 10. The HV-ECU 10 enables power supply from the first storage battery 50 to the motors 11 and 12 through the PCU 40 by switching the relays SMR1 and SMR2 from the open state to the closed state. The HV-ECU 10 switches each of the relays SMR1, 2 from the open state to the closed state when the vehicle power-on state is IGON and the user operates the brake.

  For example, when the user carrying the electronic key operates the push switch of the vehicle, the vehicle power-on state sequentially shifts to each of the ignition-off (IGOFF), accessory-on (ACCON), and ignition-on (IGON) states. To do. Here, IGOFF is a power-on state in which each of the relays SMR1, 2 is in an open state and an AC relay (not shown) is in an open state. ACCON is a power-on state in which power is supplied to the first device group 60 and the second device group 65. IGON is a power-on state that outputs a request to shift each relay SMR1, 2 from the open state to the closed state.

  The HV-ECU 10 calculates a command torque necessary for driving the first motor 11 in accordance with a user's accelerator operation amount when the vehicle power-on state is ReadyON. The HV-ECU 10 controls the PCU 40 to control the torque of the traveling motor MG to a command torque.

  The HV-ECU 10 is communicably connected to the DDCs 30 and 35 via the in-vehicle network interface 14. The HV-ECU 10 can transmit the first voltage command value V1 * and the second voltage command value V2 * to the DDCs 30 and 35 through the in-vehicle network interface 14. As the in-vehicle network interface 14, for example, a known interface such as CAN (Controller Area Network) or LIN (Local Interconnect Network) can be used. Hereinafter, the in-vehicle network interface 14 is referred to as an in-vehicle NIF 14.

  The control system 100 includes a first voltage sensor 21, a second voltage sensor 22 corresponding to a voltage detection unit, and a third voltage sensor 23. The first voltage sensor 21 is connected in parallel to the plus side terminal and the minus side terminal of the first storage battery 50, and detects the first inter-terminal voltage Vb1r. The second voltage sensor 22 is connected in parallel to the second storage battery 55 between the first sub-wiring SL1 and the second sub-wiring SL2, and detects the second terminal voltage Vb2r. The third voltage sensor 23 is connected in parallel with the smoothing capacitor 41 between the first high-voltage line HL1 and the second high-voltage line HL2, and detects the inter-terminal voltage Vcr of the smoothing capacitor 41.

  The control system 100 includes a current sensor 24 for detecting the output current Iout of the first DDC 30. In FIG. 1, the current sensor 24 is connected to the first DDC 30 side of the first sub-wiring SL1 with respect to the first power supply wiring SP1 and detects the output current Iout. Output results of the sensors 21 to 24 are output to the HV-ECU 10 through the in-vehicle NIF 14.

  Next, the power supply control performed by the HV-ECU 10 will be described using the flowchart of FIG. The process shown in the flowchart of FIG. 3 is repeatedly performed by the HV-ECU 10 at a predetermined control cycle. In FIG. 3, steps S13 and S19 correspond to the opening / closing control unit.

  In step S11, it is determined whether ReadyON is requested as a power-on state of the vehicle. When the power-on state of the vehicle is IGON and the brake operation by the user is detected, it is determined that ReadyON is requested.

  If it is determined that ReadyON is requested, the process proceeds to step S12, and it is determined whether or not the smoothing capacitor 41 needs to be precharged. If the charge on the smoothing capacitor 41 is small and the voltage Vcr between the terminals of the smoothing capacitor 41 is low, an inrush current may flow inside the PCU 40 when the relays SMR1 and SMR2 are switched to the closed state. For example, when the inter-terminal voltage Vcr of the smoothing capacitor 41 is less than the capacitor threshold Thc, it is determined that precharging is required to make the inter-terminal voltage Vcr of the smoothing capacitor 41 equal to or higher than the capacitor threshold Thc. On the other hand, if it is determined that precharging is not necessary, the process proceeds to step S18.

  If it is determined that the smoothing capacitor 41 needs to be precharged, the process proceeds to step S13, and the load SW 70 is controlled to be closed. By controlling the load SW 70 to be closed, the third input / output terminal Tio3 of the first DDC 30 and the first output terminal To1 of the second DDC 35 are electrically connected through the first sub-wiring SL1.

  In step S14, the second DDC 35 is stepped down. Specifically, the second voltage command value V2 * for causing the second drive unit 36 to perform a step-down operation is output to the second control unit 37 through the in-vehicle NIF 14.

  In step S15, the first DDC 35 is boosted. Specifically, a first voltage command value V1 * for boosting the first drive unit 31 is output to the first control unit 32 through the in-vehicle NIF 14.

  FIG. 4 is a diagram for explaining the current flowing through each line when the smoothing capacitor 41 is precharged. In FIG. 4, for the sake of convenience, a part of the drawing is omitted. Through the processing in steps S13 to S15, the second DDC 35 steps down the input voltage supplied from the first storage battery 50 via the first high voltage line HL1 and the fifth high voltage line HL5. The first DDC 30 boosts the second output voltage V2r supplied from the second DDC 35 via the first sub-wiring SL1. Therefore, a current flows into the smoothing capacitor 41 via the third high-voltage line HL3, and the smoothing capacitor 41 is precharged.

  In step S16, it is determined whether or not the precharge of the smoothing capacitor 41 is completed. For example, when the inter-terminal voltage Vcr of the smoothing capacitor 41 is equal to or higher than the capacitor threshold Thc, it is determined that the precharge is completed. In addition to this, it may be determined that the precharge has been completed based on the elapsed time since the execution of the process of step S15. On the other hand, if it is determined that the precharge has not ended, the process waits until it is determined in step S16 that the precharge has ended, via step S17. If it is determined in step S16 that the process has ended, the process proceeds to step S18.

  Next, power supply to the first device group 60 and the second device group 65 is started in steps S18 to S21. FIG. 5 is a diagram for explaining the current flowing through each line when the first device group 60 and the second device group 65 are fed.

  In step S18, the relays SMR1 and SMR2 are controlled to be closed. Therefore, the 1st storage battery 50 and PCU40 are electrically connected via high voltage line HL1, HL2.

  In step S19, the load SW 70 is controlled to an open state. Therefore, the electrical connection between the third input / output terminal Tio3 of the first DDC 30 and the first output terminal To1 of the second DDC 35 via the first sub-wiring SL1 is released.

  In step S20, the second DDC 35 is stepped down. Specifically, the second voltage command value V2 * for causing the second drive unit 36 to perform a step-down operation is output to the second control unit 37 through the in-vehicle NIF 14. Therefore, as shown in FIG. 5, the input voltage supplied from the first storage battery 50 is supplied to the first input terminal Ti1 of the second DDC 30 via the fifth high-voltage line HL5. Then, the second output voltage V2r converted by the step-down operation of the second DDC 35 is supplied from the first output terminal To1 to the first sub-wiring SL1. The second output voltage V2r is supplied to the second device group 65 via the second power supply wiring SP2, and the second device group 65 is supplied with power.

  In step S21, the first DDC 35 is stepped down. Specifically, the first voltage command value V1 * for causing the first drive unit 31 to perform a step-down operation is output to the first control unit 32 through the in-vehicle NIF 14. Therefore, as shown in FIG. 5, the input voltage supplied from the first storage battery 50 is supplied to the first input / output terminal Tio1 of the first DDC 30 via the third high-voltage line HL3. The first output voltage V1r converted by the step-down operation of the first DDC 30 is supplied from the third input / output terminal Tio3 to the first sub-wiring SL1. The first output voltage V1r is supplied to the first device group 60 via the first power supply wiring SP1, and the first device group 60 is supplied with power.

  When the process of step S21 ends, the process of FIG. 3 is temporarily ended.

  According to this embodiment described above, the following effects are obtained.

  The load SW 70 switches the electrical connection between the output side of the first DDC 30 and the output side of the second DDC 35 from the conduction state to the cutoff state, so that the first output voltage V1r from the first DDC 30 is applied to the second power supply line SP2. Without being applied to the first power supply line SP1. Further, the second output voltage V2r from the second DDC 35 is applied to the second power supply line SP2 without being applied to the first power supply line SP1. As a result, a voltage suitable for the first device group 60 and the second device group 65 can be supplied.

  A second storage battery 55 connected to the first sub-wiring SL1 on the first DDC 30 side with respect to the load SW 70 is provided. With the above configuration, fluctuations in the voltage value of the first sub-wiring SL1 are suppressed by the inter-terminal voltage of the second storage battery 55. Therefore, fluctuations in the power supplied to the first device group 60 can be suppressed.

  The first output voltage V1r of the first DDC 30 supplied to the first device group 60 is included in the first voltage range RV1 in which the power conversion efficiency of the first DDC 30 is equal to or higher than the efficiency threshold Thη, and is supplied to the second device group 65 The second output voltage V2r to be included is included in the second voltage range RV2 in which the power conversion efficiency of the second DDC is equal to or higher than the efficiency threshold Thη. With the above configuration, the first DDC 30 and the second DDC 35 can be operated with high power conversion efficiency. In addition, the first and second output voltages V1r and V2r are set in a range in which the efficiency of the first and second device groups 60 and 65 is high, so that the first device group 60 and the first device group 60 can be obtained with high power conversion efficiency. The two device groups 65 can be operated.

(Second Embodiment)
In the second embodiment, a description will be given focusing on a configuration different from the first embodiment.

  If the output voltage difference between the first DDC 30 and the second DDC 35 is large, current easily flows through the load SW 70 when the load SW 70 is opened and closed, resulting in switching loss. Therefore, in the second embodiment, the HV-ECU 10 performs control for suppressing the switching loss of the load SW 70 when the opening / closing of the load SW 70 is controlled.

  FIG. 6 is a process performed by the HV-ECU 10 in step S19 of FIG. In FIG. 6, steps S32 to S38 correspond to a voltage control unit.

  In step S31, the detection value of the second voltage sensor 22 is acquired as the second inter-terminal voltage Vb2r of the second storage battery 55.

  In step S32, the first voltage command value V1 * of the first DDC 30 is compared with the second terminal voltage Vb2r acquired in step S31.

  When the first voltage command value V1 * is larger than the second terminal voltage Vb2r, the process proceeds to step S33. In step S33, the first voltage command value V1 * is set to a value smaller than the second terminal voltage Vb2r. Specifically, a value obtained by subtracting the correction value ΔV1 from the second terminal voltage Vb2r is set as the first voltage command value V1 *.

  In step S33, the first output voltage V1r of the first DDC 30 is reduced by setting the first voltage command value V1 * to a value smaller than the second terminal voltage Vb2r. Then, when the first output voltage V1r becomes smaller than the second terminal voltage Vb2r, the power supply from the first DDC 30 to the first device group 60 is stopped, and the first device group 60 is supplied with power by the second storage battery 55. Is done. In order to determine whether to stop power supply from the first DDC 30 to the first device group 60, in step S34, based on the detection result of the current sensor 24, the output current Iout flowing through the first sub-wiring SL1 is transferred from the second storage battery 55 to the first DDC 30. It is determined whether it is flowing in the direction of. When the output current Iout does not flow from the second storage battery 55 in the direction of the first DDC 30, the first output voltage V1r is not equal to or lower than the second terminal voltage Vb2r, and the process returns to step S33.

  When the output current Iout is flowing from the second storage battery 55 to the first DDC 30, in step S35, the first voltage command value V1 * set in step S33 is set as the second voltage command value V2 * of the second DDC 35. Therefore, the second voltage command value V2 * is a value equal to or lower than the second terminal voltage Vb2r acquired in step S31.

  In step S39, the load SW 70 is controlled from the closed state to the open state. FIG. 7 is a graph for explaining changes in the output voltages V1r and V2r and the second inter-terminal voltage Vb2r when the first voltage command value V1 * is larger than the second inter-terminal voltage Vb2r. FIG. 7 shows an example in which the first output voltage V1r is higher than the second output voltage V2r.

  At time t1, the first voltage command value V1 * is set to a value lower than the second terminal voltage Vb2r, so that the first output voltage V1r decreases during the period from time t1 to t2. In addition, the first device group 60 is fed by the second storage battery 55 via the first feeding line SP1. Therefore, the second terminal voltage Vb2r of the second storage battery 55 is lowered. In addition, since the first voltage command value V1 * is controlled to be smaller than the second terminal voltage Vb2r, the first voltage command value V1 * decreases as the second terminal voltage Vb2r decreases. To do.

  At time t2, the second voltage command value V2 * is set to the same value as the first voltage command value V1 *, whereby the second output voltage V2r changes. As a result, the first output voltage V1r and the second output voltage V2r approach the same value, and the voltage difference between both terminals of the load SW 70 becomes low. At time t3, the load SW 70 is controlled from the closed state to the open state. At time t3-t4, since the voltage difference between both terminals of the load SW 70 is a low value, the current flowing through the load SW 70 is suppressed. As a result, switching loss is reduced.

  Returning to the description of FIG. 6, when the first voltage command value V1 * is equal to or lower than the second terminal voltage Vb2r in step S32, the process proceeds to step S36. In step S36, the first voltage command value V1 * is set to a value larger than the second terminal voltage Vb2r. Specifically, a value obtained by adding the correction value ΔV2 to the second terminal voltage Vb2r is set as the first voltage command value V1 *.

  In step S36, the first voltage command value V1 * is set to a value larger than the second terminal voltage Vb2r, so that the first output voltage V1r becomes larger than the second terminal voltage Vb2r, and the second storage battery. Power supply from 55 to the first device group 60 is stopped. Therefore, in step S37, it is determined whether or not the output current Iout is flowing in the direction from the first DDC 30 to the second storage battery 55. When the output current Iout does not flow in the direction from the first DDC 30 to the second storage battery 55, the first output voltage V1r is not equal to or higher than the second terminal voltage Vb2r, and the process returns to step S36.

  When the output current Iout becomes equal to or smaller than the second current threshold value Thi2, in step S38, the first voltage command value V1 * set in step S36 is set as the second voltage command value V2 *. In step S39, the load SW 70 is controlled from the closed state to the open state.

  FIG. 8 is a graph for explaining changes in the output voltages V1r, V2r and the second terminal voltage Vb2r when the first voltage command value V1 * is smaller than the second terminal voltage Vb2r.

  At time t11, the first output voltage V1r increases by setting the first voltage command value V1 * to a value greater than the second terminal voltage Vb2r. At time t11-t12, the second storage battery 55 is charged by the first DDC 30 when the first output voltage V1r becomes higher than the second terminal voltage Vb2r. In FIG. 8, after the time t12, the second terminal voltage Vb2r starts to increase. By controlling the first voltage command value V1 * to be larger than the second terminal voltage Vb2r, the first voltage command value V1 * increases as the second terminal voltage Vb2r increases.

  At time t12, the second voltage command value V2 * is set to the same value as the first voltage command value V1 *, so that the second output voltage V2r increases. As a result, the first output voltage V1r and the second output voltage V2r approach the same value, and the voltage difference between both terminals of the load SW 70 becomes low.

  At time t13, the load SW 70 is controlled from the closed state to the open state. In the period from time t13 to time t14, the voltage difference between both terminals of the load SW 70 is a low value, so that the current flowing through the load SW 70 is suppressed. As a result, the switching loss in the load SW 70 is reduced.

  When the process of step S37 ends, the process returns to step S19 of FIG.

  According to this embodiment described above, the following effects are obtained.

  The HV-ECU 10 causes the first voltage command value V1 * and the second voltage command to match the respective output voltages V1r and V2r of the first DDC 30 and the second DDC 35 when the load SW 70 switches between the conductive state and the cut-off state. It was decided to control the value V2 *. In this case, a voltage difference generated at both ends of the load SW 70 can be reduced, and a switching loss at the time of opening and closing can be suppressed.

  Further, the HV-ECU 10 controls the first voltage command value V1 * and the second voltage command value V2 * so that the output voltages V1r, V2r coincide with the second terminal voltage Vb2r of the second storage battery 55. did. With the above configuration, even in the configuration in which the second storage battery 55 is connected in the first sub-wiring SL1, the current generated in the load SW 70 can be reduced.

(Modification)
The current sensor 24 may be provided on the low voltage side of the first drive unit 31 in the first DDC 30 and detect a current value on the low voltage side of the first drive unit 31. In this case, the processes of steps S34 and S37 are performed as follows. Based on the current value on the low voltage side of the first drive unit 31 detected by the current sensor 24, the current value flowing on the high voltage side of the first drive unit 31 is calculated. Then, the direction of the output current Iout flowing through the first sub-wiring SL1 is determined based on the calculated current value. The current sensor 24 may be provided on the high voltage side of the first drive unit 31 in the first DDC 30 and detect the current value on the high voltage side of the first drive unit 31.

  When the first drive unit 31 includes a voltage sensor that detects a voltage value on the high voltage side, based on the voltage difference between the detected value detected by the voltage sensor and the second terminal voltage Vb2r of the second storage battery 55, The direction of the output current Iout flowing through the first sub-wiring SL1 may be determined.

  In step S35 of FIG. 6, the HV-ECU 10 acquires the first output voltage V1r of the first DDC 30, and calculates the second voltage command value V2 * so that the second output voltage V2r of the second DDC 35 becomes the first output voltage V1r. May be.

  The switching loss of the load SW 70 can also occur during control from the open state to the closed state. Therefore, in step S13 of FIG. 3, the HV-ECU 10 may perform a process for reducing the switching loss. In this case, in step S39 in FIG. 6, the load SW 70 is controlled from the open state to the closed state.

(Third embodiment)
In the third embodiment, a description will be given focusing on the configuration different from the first embodiment.

  FIG. 9 is a configuration diagram of a control system 100 according to the third embodiment. The control system 100 shown in FIG. 9 is different from the first embodiment in that the second storage battery 55 is not connected to the first sub-wiring SL1.

  Also in the third embodiment, the HV-ECU 10 performs control for suppressing the switching loss of the load SW 70 when controlling the load SW 70 from the closed state to the open state.

  FIG. 10 is a flowchart illustrating the process performed in step S19 of FIG. 3 in the third embodiment.

  In step S41, the first voltage command value V1 * set in the first DDC 35 is acquired.

  In step S42, the second voltage command value V2 * of the second DDC 35 is set as the first voltage command value V1 * acquired in step S41. Therefore, the first DDC 30 and the second DDC 35 operate with the same output voltage command value.

  In step S43, the process waits until a predetermined time elapses. After elapse of the predetermined time, the second output voltage V2r changes to a value corresponding to the second voltage command value V2 * set in step S42. In step S44, the load SW 70 is controlled from the closed state to the open state.

  When the process of step S44 is completed, the process returns to step S19 of FIG.

  FIG. 11 is a graph illustrating changes in the output voltages V1r, V2r and the second inter-terminal voltage Vb2r according to the third embodiment. FIG. 11 illustrates a case where the first output voltage V1r is higher than the second output voltage V2r.

  At time t21, the first voltage command value V1 * and the second voltage command value V2 * are set to the same value, so that the second output voltage V2r rises during the period of time t21-t22, and the first output The voltage V1r and the second output voltage V2r are close to each other.

  At time t23, the load SW 70 is controlled from the closed state to the open state. At time t23-t24, the voltage difference between both terminals of the load SW 70 has a low value, so that the current flowing through the load SW 70 is suppressed. As a result, switching loss is reduced.

  According to this embodiment described above, the following effects are obtained.

  Even in the configuration in which the second storage battery 55 is not connected in the first sub-wiring SL1, the current generated in the load SW 70 can be reduced.

(Modification)
In step S42 of FIG. 10, the HV-ECU 10 acquires the first output voltage V1r of the first DDC 30, and the second voltage command value V2 * so that the second output voltage V2r of the second DDC 35 becomes a value close to the first output voltage V1r. May be calculated.

  The switching loss of the load SW 70 can also occur during control from the open state to the closed state. Therefore, in step S13 of FIG. 3, the HV-ECU 10 may perform a process for reducing the switching loss. In this case, in step S44 of FIG. 10, the load SW 70 is controlled from the open state to the closed state.

(Fourth embodiment)
In the fourth embodiment, a description will be given focusing on a configuration different from the first embodiment.

  FIG. 12 is a configuration diagram of a control system 100 according to the fourth embodiment. The control system 100 shown in FIG. 12 includes a first conduction switch 71 that switches between a conduction state and a non-conduction state in the first sub-wiring SL1, and a second conduction switch 72. In the present embodiment, the first conduction switch 71 corresponds to a first device switching unit, and the second conduction switch 72 corresponds to a second device switching unit. Hereinafter, the conduction switches 71 and 72 are referred to as conduction SWs 71 and 72, respectively.

  The first conduction SW 71 is provided on the first DDC 30 side with respect to the connection point of the first power supply wiring SP1 in the first sub-wiring SL1. The second conduction SW 72 is provided on the second DDC 35 side of the first sub-wiring SL1 with respect to the connection point of the second power supply wiring SP2. Further, each of the conduction SWs 71 and 72 is connected to the HV-ECU 10, and the HV-ECU 10 controls switching between the open state and the closed state.

  When the load SW 70 is controlled to be closed and the first conduction SW 71 is controlled to be closed, the electrical connection of the first power supply line SP1 to the first sub-wiring SL1 is maintained. On the other hand, when the load SW 70 is controlled to be in the closed state and the first conduction SW 71 is controlled to be in the open state, the electrical connection of the first power supply wiring SP1 to the first sub wiring SL1 is interrupted.

  When the load SW 70 is controlled to be closed and the second conduction SW 72 is controlled to be closed, the electrical connection of the second power supply line SP2 to the first sub-wiring SL1 is maintained. On the other hand, when the load SW 70 is controlled to be in the closed state and the second conduction SW 72 is controlled to be in the open state, the electrical connection of the second power supply wiring SP2 to the first sub wiring SL1 is interrupted.

  Next, a power cut-off process performed by the HV-ECU 10 in the fourth embodiment will be described with reference to the flowchart of FIG. The process shown in the flowchart of FIG. 13 is repeatedly performed by the HV-ECU 10 at a predetermined control cycle.

  In step S51, it is determined whether or not the first DDC 30 has failed. For example, the failure of the first DDC 30 is a short failure of the first DDC 30. This short circuit failure is a failure in which a part of the circuit of the first DDC 30 is short-circuited and a closed circuit including the second storage battery 55 and a part of the first DDC 30 is formed. When the first DDC 30 is short-circuited, a large current may flow through the closed circuit. Therefore, when a short failure of the first DDC 30 occurs, it is necessary to prevent a large current from flowing through the closed circuit. For example, whether or not the first DDC 30 has a short circuit failure is determined according to the value of the output current Iout.

  When the failure of the first DDC 30 is determined, in step S52, the first conduction SW 71 is controlled to the open state. Therefore, the closed circuit is not formed. Note that the electrical connection of the first power supply wiring SP1 to the first sub-wiring SL1 is cut off by the process of step S52. As a result, power supply to the first device group 60 by the first DDC 30 is stopped. Step S52 corresponds to the first device controller.

  In step S53, notification processing that power is not supplied to the first device group 60 is performed. This process notifies the vehicle user that an abnormality has occurred.

  On the other hand, if it is not determined in step S51 that the first DDC 30 has failed, it is determined in step S54 whether the second DDC 35 has failed. For example, the failure of the second DDC 35 is a short-circuit failure like the first DDC 30.

  If it is determined that the second DDC 35 has failed, the second conduction SW 72 is controlled to be in an open state in step S55. For this reason, the electrical connection of the second power supply line SP2 to the first sub-line SL1 is interrupted. As a result, power supply to the second device group 65 by the second DDC 35 is stopped. Step S55 corresponds to the second device control unit.

  In step S56, notification processing that the second device group 65 is not powered is performed. If it is not determined in step S54 that the second DDC 30 has failed, the process in FIG. 13 is temporarily terminated.

  According to this embodiment described above, the following effects are obtained.

  When the HV-ECU 10 determines the failure of the first DDC 30 or the failure of the second DDC 35, the power supply from the first DDC 30 to the first device group 60 or the power supply from the second DDC 35 to the second device group 65 is stopped. Therefore, it is possible to prevent a large current from flowing to the sub wirings SL1 and SL2. In addition, in a state where power supply to each of the device groups 60 and 65 by any one of the DDCs 30 and 35 in which the failure has occurred is stopped, the vehicle is configured by any one of the DDCs 30 and 35 in which no failure has occurred and the first storage battery 50. It can be run. As a result, the user can save the vehicle.

(Modification)
The first sub-wiring SL1 may be provided with either the first conduction SW 71 or the second conduction SW 72.

(Modification)
The first and second device switching units may be fuses instead of the conduction SWs 71 and 72. In this case, in the first sub-wiring SL1, the first fuse provided on the first DDC 30 side of the connection point of the first device group 60 electrically connects the first device group 60 and the 1DDC 30. Closed. On the other hand, it is an open state that the first fuse is blown. Similarly, the state in which the second fuse provided on the second DDC 35 side of the connection point of the second device group 65 electrically connects the second device group 65 and the second DDC 35 is a closed state. On the other hand, it is an open state that the second fuse is blown.

(Other embodiments)
The load SW 70 may be composed of other things such as an IGBT instead of the MOSFET. In short, any configuration may be used as long as bidirectional current flow is prevented when the energization operation is not performed and current flow is permitted when the energization operation is performed.

  Control system 100 may be mounted on a vehicle other than a hybrid vehicle.

  The control system 100 may be mounted on a device other than the vehicle.

  The control units other than the HV-ECU 10 may perform the processes in FIGS.

  Instead of the second storage battery 55, a capacitor may be used.

  Instead of making the storage capacity of the second storage battery 55 smaller than the storage capacity of the first storage battery 50, the second storage battery 55 and the first storage battery 50 may have the same storage capacity. In the first embodiment, the storage capacity of the second storage battery 55 may be larger than the storage capacity of the first storage battery 50.

  The configuration for switching the high voltage lines HL1 and HL2 is not limited to the relays SMR1 and SMR2. The provision of the relays SMR1, 2 on the high-voltage lines HL1, HL2 is merely an example, and the relays SMR1, 2 may not be provided on the high-voltage lines HL1, HL2.

  As for the 2nd storage battery 55, a plus side terminal and a minus side terminal may be connected to each sub wiring SL1 and SL2 by the 2nd DDC35 side rather than load SW70.

  The first DDC 30 may be a step-down converter other than the buck-boost converter. The second DDC 35 may be a bidirectional converter other than the unidirectional converter.

  The process of the control system 100 when controlling the load SW 70 to the closed state is not limited to precharging the smoothing capacitor 41.

  The precharge for the smoothing capacitor 41 may be performed as follows. The first DDC 30 boosts the second terminal voltage Vb2r of the second storage battery 55 and outputs the boosted voltage to the third high-voltage line HL3. For this reason, the smoothing capacitor 41 is fed through the third high-voltage line HL3 and the first high-voltage line HL1, so that precharging is performed.

  DESCRIPTION OF SYMBOLS 10 ... HV-ECU, 30 ... 1st DC / DC converter, 35 ... 2nd DC / DC converter, 50 ... 1st storage battery, 60 ... 1st apparatus group, 65 ... 2nd apparatus group, 70 ... Load SW, 100 ... control system.

Claims (11)

Applied to a power supply system comprising a main power storage device (50) and main supply wirings (HL1 to HL6) connected to the main power storage device,
A first DC / DC converter (30) connected to the main supply wiring for stepping down the output voltage of the main power storage device;
A second DC / DC converter (35) connected to the main supply wiring for stepping down the output voltage of the main power storage device;
Sub-wirings (SL1, SL2) for connecting the output side of the first DC / DC converter and the output side of the second DC / DC converter and connecting the first device (60) and the second device (65);
The sub-wiring is provided between a connection point with the first device and a connection point with the second device, and an output side of the first DC / DC converter and an output side of the second DC / DC converter. A power conversion device comprising: a main switching unit (70) that switches a connection state via the sub-wiring between a conduction state and a cutoff state.   The power converter according to claim 1, further comprising an open / close control unit that controls switching between the conduction state and the cutoff state by the main switching unit.   The power converter according to claim 1, further comprising a sub power storage device connected to the sub wiring.   The output voltage of the first DC / DC converter is set so that the output voltages of the first DC / DC converter and the second DC / DC converter coincide with each other when the main switching unit switches between the conduction state and the cutoff state. The power converter according to any one of claims 1 to 3, further comprising a voltage control unit that controls a command value and an output voltage command value of the second DC / DC converter. A sub power storage device (55) connected to the sub wiring;
A voltage detector (22) for detecting a voltage between terminals of the sub power storage device,
The voltage control unit includes an output voltage command value of the first DC / DC converter and the output voltage command value of the first DC / DC converter so as to match the output voltages of the first DC / DC converter and the second DC / DC converter with the detected inter-terminal voltage. The power converter of Claim 4 which controls the output voltage command value of a 2nd DC / DC converter.   Provided in the sub-wiring on the first DC / DC converter side than the first device, and electrically connected the output side of the first DC / DC converter and the first device by being closed; The first device switching unit (71) that cuts off an electrical connection between the output side of the first DC / DC converter and the first device by being in an open state. The power converter according to item.   The power conversion device according to claim 6, further comprising a first device control unit that switches the first device switching unit from a closed state to an open state when a failure of the first DC / DC converter is determined.   Provided in the sub-wiring on the second DC / DC converter side than the second device, and electrically connected the output side of the second DC / DC converter and the second device by being closed, The switch part (72) for 2nd apparatuses which interrupts | blocks the electrical connection of the output side of the said 2nd DC / DC converter and the said 2nd apparatus by being made into an open state is any one of Claims 1-7. The power converter according to item.   The power converter according to claim 8, further comprising a second device control unit that switches the second device switching unit from the closed state to the open state when a failure of the second DC / DC converter is determined. When the output voltage output from the first DC / DC converter to the first device is a first output voltage, and the output voltage output from the second DC / DC converter to the second device is a second output voltage,
The first output voltage is included in a first voltage range in which the power conversion efficiency of the first DC / DC converter is a predetermined value or more,
The power converter according to any one of claims 1 to 9, wherein the second output voltage is included in a second voltage range in which power conversion efficiency of the second DC / DC converter is equal to or greater than the predetermined value. . The power conversion device according to any one of claims 1 to 10,
A control system comprising the power supply system.

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