Power supply system

Abstract

A power supply system that performs more reasonable control in which a charging / feeding device is connected to both ends of a target relay, which is one of a plurality of relays of a switching circuit and a system main relay, via first and second relays, and a control device controls the charging / feeding relay, the first and second relays, and the charging / feeding device. The voltage across the target relay is adjusted in a state in which the charging / power supply relay is turned off and the first and second relays are turned on.

Description

Technical Field

[0001] This disclosure relates to power supply systems. Background Technology

[0002] Conventionally, power systems of this type have included a first battery connected to a power line, a second battery connected to a parallel connecting line connecting the positive and negative terminals of the power line, a charging device for supplying power from an external power source to the first and second batteries, and a switching circuit (see, for example, Patent Document 1). The switching circuit includes: a first parallel relay mounted on the positive terminal; a second parallel relay mounted on the parallel connecting line; and a series relay mounted on the series connecting line connecting the positive terminal (the side of the first parallel relay closer to the first battery) to the parallel connecting line (the side of the parallel connecting line connecting the first parallel relay closer to the second battery).

[0003] Existing technical documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2021-151041

[0005] However, in the aforementioned power supply system, if a voltage difference occurs across the first parallel relay when it is to be disconnected, a situation may arise where the first parallel relay is disconnected while current is flowing through it. In this case, if the voltage difference across the first parallel relay is completely eliminated, a relatively long time is required before disconnecting the first parallel relay. Furthermore, raising the temperature of the first and second batteries when they are cold is considered an important issue. To address these issues, more efficient control is desired. Summary of the Invention

[0006] The main purpose of the power supply system disclosed herein is to achieve more rational control.

[0007] To achieve the aforementioned main objectives, the power supply system of this disclosure employs the following means. The power supply system of this disclosure comprises: a first battery connected to a power line; a second battery connected to the positive terminal of the power line and connected to the negative terminal of the power line via a parallel connection line; a switching circuit having multiple relays that switches the connection between the first battery and the second battery to a series connection or a parallel connection; a charging power supply device having a voltage conversion circuit that exchanges power between an external power line supplied with power from an external power source and a charging power supply line during voltage conversion; a system main relay mounted on the power line; a charging power supply relay mounted on the charging power supply line; and a control device that controls the switching circuit, the charging power supply device, and the charging power supply relay, wherein the charging power supply device is connected via the first relay and the second relay to the two ends of a target relay, which is one of the multiple relays in the switching circuit and one of the system main relays; the control device controls the charging power supply relay, the first relay, the second relay, and the charging power supply device such that the voltage across the target relay is adjusted when the charging power supply relay is disconnected and the first relay and the second relay are connected. Attached Figure Description

[0008] Figure 1 This is a schematic structural diagram of the power supply system 10 according to an embodiment of the present disclosure.

[0009] Figure 2 This is a schematic structural diagram showing the structure of the charging power supply device 40.

[0010] Figure 3 This is an explanatory diagram used to illustrate the current path when performing control before disconnection.

[0011] Explanation of reference numerals in the attached figures:

[0012] 10 Power supply system, 30 Switching circuits, 70 Electronic control unit (ECU). Detailed Implementation

[0013] The embodiments (implementations) for carrying out this disclosure will be described with reference to the accompanying drawings. Figure 1 This is a schematic structural diagram of the power supply system 10 according to an embodiment of the present disclosure. Figure 2This is a schematic structural diagram showing the general structure of the charging power supply device 40. The power system 10 is installed in electric vehicles and hybrid vehicles, and includes first and second batteries 12 and 13, a motor 20, an inverter 22, a switching circuit 30, the charging power supply device 40, and an electronic control unit (control device, hereinafter referred to as "ECU") 70. The power system 10 can use power from an external power source EPS such as its own home or a charging station to charge the first battery 12 and the second battery 13, or use power from the first battery 12 and the second battery 13 to supply power to a load (not shown) connected to the external power source EPS.

[0014] The first and second batteries 12 and 13 are configured as secondary batteries with a rated voltage slightly lower than the first voltage Vs1 (e.g., 400V) and of the same specifications. The positive terminal of the first battery 12 is connected to the positive line 14a of the power line 14, and the negative terminal is connected to the negative line 14b of the power line 14. The positive terminal of the second battery 13 is connected to the positive line 14a of the power line 14, and the negative terminal is connected to the negative line 14b via a parallel connection line 15. A system main relay SMR is installed on the side of the power line 14 closer to the inverter 22 than the second battery 13.

[0015] Motor 20, for example, has a rotor with permanent magnets embedded in its rotor core and a stator with three-phase (U-phase, V-phase, W-phase) coils wound in its stator core. Inverter 22 is connected to power line 14 and uses power from first and second batteries 12 and 13 to drive motor 20. Inverter 22 is controlled by ECU 70.

[0016] The switching circuit 30 includes parallel relays (object relays) 31, parallel relay 32, and series relay 33. Parallel relay 31 is mounted on the positive line 14a. Parallel relay 32 is mounted on parallel connecting line 15. Series relay 33 is mounted on series connecting line 34, which connects the position of the positive line 14a (near the first battery 12 than parallel relay 31) to the position of the parallel connecting line 15 (near the second battery 13 than parallel relay 32). The switching circuit 30 connects the first and second batteries 12 and 13 in series by disconnecting parallel relays 31 and 32 and connecting series relay 33. Alternatively, the switching circuit 30 connects the first and second batteries 12 and 13 in parallel by connecting parallel relays 31 and 32 and disconnecting series relay 33. Parallel relays 31, 32, and series relay 33 are controlled by ECU 70.

[0017] The charging power supply device 40 includes charging power supply circuits 42 and 44. Charging power supply circuits 42 and 44 are connected via relays (charging power supply relays) 60 and 62 to the positive line 14a and negative line 14b of the power line 14, closer to the inverter 22 than the system main relay SMR. Charging power supply circuit 42 is connected via relay 66 to the side of the positive line 14a closer to the second battery 13 than the parallel relay 31, and to the side of the parallel connection line 15 closer to the second battery 13 than the parallel relay 32. Figure 2As shown, the charging power supply circuit 42 includes a noise filter NF42, a power factor correction (PFC) circuit 42a, a smoothing capacitor C42, and a DC / DC converter (voltage conversion circuit) 42b. The noise filter NF42 is a known noise filter configured to suppress the inflow of noise from the external power supply EPS and the outflow of noise to the external power supply EPS. The smoothing capacitor C42 smooths the voltage on the power line PL42 connecting the PFC42a and the DC / DC converter 42b. The DC / DC converter 42b is configured as a bidirectional DC / DC converter, converting DC power to DC power at different voltages. The PFC42a and the DC / DC converter 42b constitute a bidirectional converter, converting AC power from the noise filter NF42 to DC power of any voltage, or converting DC power from the charging power supply line PLC to AC power. When connector 46, which connects to the external power line PLe, and connector Cn, which connects to the external power supply EPS, are connected and relay 60 is turned on, the charging power supply circuit 42 converts the AC power supplied from the external power supply EPS via connector Cn, 46, and external power line PLe into DC power and supplies it to the first and second batteries 12 and 13 via charging power supply line PLC and relay 60 to charge the first and second batteries 12 and 13. Additionally, when connector 46 is connected to connector Cn and relay 60 is turned on, the charging power supply circuit 42 converts the DC power input from the first and second batteries 12 and 13 via relay 60 and charging power supply line PLC into AC power and supplies it to a load (not shown) on the external power supply EPS side via external power line PLe, connector 46, and Cn. The charging power supply circuit 44 is connected via relay 64 to the side of the positive line 14a closer to the first battery 12 than the parallel relay 31, and to the side of the parallel connection line 15 closer to the second battery 13 than the parallel relay 32. The charging power supply circuit 44 has the same structure as the charging power supply circuit 42, and includes a noise filter NF44, a power factor correction circuit (PFC) 44a, a smoothing capacitor C44, and a DC / DC converter 44b. When the connector 46, which is connected to the external power line PLe, and the connector Cn, which is connected to the external power supply EPS, are connected and the relay 62 is turned on, the charging power supply circuit 44 converts the AC power supplied from the external power supply EPS through the connectors Cn, 46, and the external power line PLe into DC power and supplies it to the first and second batteries 12 and 13 through the charging power supply line PLs and the relay 62 to charge the first and second batteries 12 and 13, or converts the DC power input from the first and second batteries 12 and 13 through the relay 62 and the charging power supply line PLs into AC power and supplies it to a load (not shown) on the external power supply EPS side through the external power line PLe, the connector 46, and Cn.

[0018] ECU 70 is configured as a CPU-centric microcomputer. Signals from various sensors are input to ECU 70. Examples of these sensors include voltage V1 from voltage sensor 42d, which detects the output voltage of charging power supply circuit 42, and voltage V2 from voltage sensor 44d, which detects the input voltage of charging power supply circuit 44. Control signals are output from ECU 70 to inverter 22, switching circuit 30 (parallel relays 31, 32, and series relay 33), charging power supply circuits 42, 44, and relays 60, 62, 64, and 66.

[0019] In the power system 10, when connector 46 and connector Cn are connected, and the voltage V1 from voltage sensor 42d is a first voltage Vs1 and a second voltage Vs2 when the system main relay SMR and relay 60 or relay 62 are turned on, ECU 70 selects parallel charging and series charging respectively. In parallel charging, by disconnecting series relays 33, 64, and 66 and turning on parallel relays 31 and 32, the first battery 12 and the second battery 13 are connected in parallel as observed from connector 46, and the first battery 12 and the second battery 13 are charged using power from the external power supply EPS. In series charging, by turning on series relay 33 and disconnecting parallel relays 31, 32, 64, and 66, the first and second batteries 12 and 13 are connected in series as observed from connector 46, and the first and second batteries 12 and 13 are charged using power from the external power supply EPS. When connectors 46 and Cn are connected, and the voltage V2 from voltage sensor 44d is the first voltage Vs1 and the second voltage Vs2 when the system main relay SMR and relay 60 or relay 62 are turned on, ECU 70 selects parallel power supply and series power supply respectively. In parallel power supply, by turning off series relays 33, 64, and 66 and turning on parallel relays 31 and 32, the first and second batteries 12 and 13 are connected in parallel as observed from connector 46, and the power from the first and second batteries 12 and 13 is supplied to the external power supply EPS side. In series power supply, by turning on series relay 33 and turning off parallel relays 31, 32, 64, and 66, the first and second batteries 12 and 13 are connected in series as observed from connector 46, and the power from the first and second batteries 12 and 13 is supplied to the external power supply EPS side.

[0020] Next, the operation of the power system 10 according to the embodiment, particularly the operation when the parallel relay 31 is disconnected, will be explained. In parallel charging or parallel power supply, the system main relay SMR is in the ON state, and relays 60 or 62 are in the ON state, while series relays 33, 64, and 66 are in the OFF state, and parallel relays 31 and 32 are in the ON state. When connector Cn is disconnected from connector 46 during parallel charging or parallel power supply, ECU 70 disconnects the ON relays in relays 60 and 62. Furthermore, before disconnecting parallel relays 31 and 32, pre-disconnection control is performed, i.e., relays 64 and 66 are ON to control the DC / DC converter 42b of the charging power supply circuit 42 and the DC / DC converter 44b of the charging power supply circuit 44, so that the voltage V1 from voltage sensor 42d is equal to the voltage V2 from voltage sensor 44d. Figure 3This is an explanatory diagram illustrating an example of the current path during pre-disconnection control. In the diagram, thick lines represent the current path. For example, as shown, the current path for pre-disconnection control is as follows: from the first battery 12 via positive line 14a, the positive side of relay 64, the positive side of charging power supply circuit 44 (positive lines of charging power supply line PLs and power line PL44), the positive line of external power line PLe, the positive side of charging power supply circuit 42 (positive lines of charging power supply line PLC and power line PL42), the positive side of relay 66, positive line 14a, the second battery 13, the negative side of relay 66, the negative side of charging power supply circuit 42 (negative lines of charging power supply line PLC and power line PL42), the negative line of external power line PLe, the negative side of charging power supply circuit 44 (negative lines of charging power supply line PLs and power line PL44), the negative side of relay 64, parallel connection line 15, and the negative side of parallel relay 32 to the first battery 12. At this time, the voltage V1 from voltage sensor 42d is the voltage on the second battery 13 side of the parallel relay 31, and the voltage V2 from voltage sensor 44d is the voltage on the first battery 12 side of the parallel relay 31. Therefore, the pre-disconnection control becomes the control to make the voltages across the parallel relay 31 equal. Moreover, if the voltage V1 from voltage sensor 42d is equal to the voltage V2 from voltage sensor 44d during the pre-disconnection control, the pre-disconnection control ends, causing relays 64 and 66 to disconnect and parallel relays 31 and 32 to disconnect. Since the parallel relay 31 is disconnected after the voltages across its terminals are made equal, protection for the parallel relay 31 can be achieved. In addition, during the pre-disconnection control, the DC / DC converters 42b and 44b of the charging power supply circuits 42 and 44 are controlled to make the voltages V1 from voltage sensor 42d equal to the voltage V2 from voltage sensor 44d, so that the voltages across the parallel relay 31 can be made equal relatively quickly to disconnect the parallel relay 31. This allows for a shorter time required for parallel charging (from the start to the end of parallel charging) and enables more efficient control.

[0021] In the power supply system 10 of the above-described embodiments, by controlling relays 60, 62, 64, 66 and the charging power supply device 40, the voltage across the parallel relays 31 is adjusted to be equal when the relays 60 and 62 are turned on and the relays 64 and 66 are turned on, thereby enabling more reasonable control.

[0022] In the above embodiments, the charging power supply device 40 includes Figure 2The charging power supply circuits 42 and 44 are shown, but only one of them may be present. For example, if the charging power supply device 40 only has the charging power supply circuit 44, it may also include... Figure 2 The positive terminal of the power line PL44 is connected to the positive terminal of the positive line 14a via the positive terminal of the relay 66, at a position closer to the second battery 13 than the parallel relay 31. The negative terminal of the power line PL44 is connected to the parallel connection line 15 via the relay 66, at a position closer to the second battery 13 than the parallel relay 32. This is to control the DC / DC converter 44b so that the voltage across the parallel relay 31, i.e., the voltage V2 from the voltage sensor 44d, is equal to the voltage Vc of the smoothing capacitor C44.

[0023] In the above embodiment, before disconnecting the parallel relays 31 and 32, the relays 64 and 66 are turned on to control the DC / DC converters 42b and 44b of the charging power supply circuits 42 and 44, so that the voltage V1 from the voltage sensor 42d is equal to the voltage V2 from the voltage sensor 44d. However, when the first battery 12 and the second battery 13 are at low temperatures in a cold state, the temperature rise of the first battery 12 and the second battery 13 can be more reasonably controlled by alternately and repeatedly performing the first control and the second control. The first control is to disconnect relays 60 and 62 and connect parallel relays 31 and 32 and relays 64 and 66, so that the voltage V1 from voltage sensor 42d is higher than the voltage V2 from voltage sensor 44d, thereby controlling the control of the DC / DC converters 42b and 44b of the charging power supply circuits 42 and 44. The second control is to control the control of the DC / DC converters 42b and 44b of the charging power supply circuits 42 and 44, so that the voltage V1 from voltage sensor 42d is lower than the voltage V2 from voltage sensor 44d.

[0024] In the above embodiment, a charging power supply device 40 is connected to both ends of the parallel relay 31, and the voltage across the parallel relay 31 is adjusted. However, the relay connected to the charging power supply device 40 can be any relay that is not prone to current flow due to the voltage difference when disconnected; it can be any relay, such as the parallel relay 32, the series relay 33, or the system main relay SMR. In this case, more reasonable control can be achieved by adjusting the voltage across the relay connected to the charging power supply device 40.

[0025] The above describes the methods for implementing this disclosure using the embodiments, but this disclosure is not limited to such embodiments in any way, and can of course be implemented in various ways without departing from the spirit of this disclosure.

Claims

1. A power supply system, comprising: The first battery connected to the power line, The second battery is connected to the positive terminal of the electric field line and also connected to the negative terminal of the electric field line via a parallel connection line. The switching circuit has multiple relays to switch the connection between the first battery and the second battery to either a series connection or a parallel connection. A charging power supply device has a voltage conversion circuit that exchanges power between an external power line supplied with power from an external power source and a charging power supply line, accompanied by voltage conversion. The system's main relay is installed on the power line; A charging power supply relay is installed on the charging power supply line; as well as The control device controls the switching circuit, the charging power supply device, and the charging power supply relay, wherein... The charging power supply device is connected to the two ends of the target relay via a first relay, a second relay, and one of the relays that constitute the switching circuit and the main relay of the system. The control device controls the charging power supply relay, the first relay, the second relay, and the charging power supply device to adjust the voltage across the target relay when the charging power supply relay is disconnected and the first relay and the second relay are connected.

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