Power supply system

Abstract

To perform more proper control.SOLUTION: In the power supply system, the charging and power feeding device is connected to both ends of a target relay serving as one relay of the plurality of relays of the switching circuit and the system main relay via first and second relays, and the control device controls the charging and power feeding relay, the first and second relays, and the charging and power feeding device such that a voltage across the target relay is adjusted while the charging and power feeding relay is turned off and the first and second relays are turned on.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to power supply systems. [Background technology]

[0002] A conventional power supply system of this type includes a first battery connected to a power line, a second battery connected to a parallel connection line that is connected to the positive and negative pole lines of the power line, a charging device that supplies 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 attached to the positive line, a second parallel relay attached to the parallel connection line, and a series relay attached to a series connection line that connects the first battery side of the first parallel relay on the positive line to the second battery side of the second parallel relay on the parallel connection line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-151041 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-described power supply system, if a voltage difference occurs across the first parallel relay when attempting to turn off the first parallel relay, the first parallel relay may be turned off while current is still flowing through it. In this case, waiting until the voltage difference across the first parallel relay is resolved would require a relatively long time to turn off the first parallel relay. Furthermore, when the first and second batteries are at low temperatures, such as when the vehicle is cold, it is recognized that raising the temperatures of the first and second batteries is an important issue. To solve these issues, more appropriate control is desired.

[0005] The power supply system of the present disclosure has a primary objective of performing more appropriate control. [Means for solving the problem]

[0006] The power supply system of the present disclosure employs the following measures to achieve the above-mentioned main object. The power supply system of the present disclosure includes: a first battery connected to a power line; a second battery connected to a positive line of the power line and connected to a negative line of the power line via a parallel connection line; a switching circuit having a plurality of relays and switching the connection between the first battery and the second battery between a series connection and a parallel connection; a charging device having a voltage conversion circuit that exchanges power between an external power line to which power from an external power source is supplied and a charging line, with voltage conversion performed; a system main relay attached to the power line; a charging relay attached to the charging line; and a control device that controls the switching circuit, the charging device, and the charging relay, wherein the charging device is connected to both ends of a target relay that is one of the plurality of relays and the system main relay in the switching circuit via first and second relays, and the control device controls the charging relay, the first and second relays, and the charging device so that the voltage across the target relay is adjusted with the charging relay turned off and the first and second relays turned on. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram of a power supply system 10 according to an embodiment of the present disclosure. [Figure 2] 2 is a schematic diagram showing the outline of the configuration of a charging device 40. FIG. [Figure 3] FIG. 4 is an explanatory diagram for explaining a current path when pre-off control is being executed. DETAILED DESCRIPTION OF THE INVENTION

[0008] Modes (embodiments) for carrying out the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a power supply system 10 according to an embodiment of the present disclosure. FIG. 2 is a schematic configuration diagram showing an outline of the configuration of a charging device 40. The power supply system 10 is mounted on an electric vehicle or a hybrid vehicle and includes first and second batteries (first and second cells) 12, 13, a motor 20, an inverter 22, a switching circuit 30, the charging device 40, and an electronic control unit (control device, hereinafter referred to as "ECU") 70. The power supply system 10 is capable of charging the first and second batteries 12, 13 using power from an external power supply EPS such as a home or a charging station, and supplying power from the first and second batteries 12, 13 to a load (not shown) connected to the external power supply EPS.

[0009] The first and second batteries 12, 13 are configured as secondary batteries having the same specifications and a rated voltage slightly lower than the first voltage Vs1 (e.g., 400 V). The positive terminal of the first battery 12 is connected to a positive line 14a of the power line 14, and the negative terminal is connected to a 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 attached to the power line 14 on the inverter 22 side of the second battery 13.

[0010] The motor 20 includes, for example, a rotor having a permanent magnet embedded in a rotor core, and a stator having a three-phase (U-phase, V-phase, W-phase) coil wound around a stator core. The inverter 22 is connected to the power line 14 and drives the motor 20 with power from the first and second batteries 12, 13. The inverter 22 is controlled by the ECU 70.

[0011] The switching circuit 30 includes a parallel relay (target relay) 31, a parallel relay 32, and a series relay 33. The parallel relay 31 is attached to the positive line 14a. The parallel relay 32 is attached to the parallel connection line 15. The series relay 33 is attached to a series connection line 34 that connects the first battery 12 side of the parallel relay 31 on the positive line 14a and the second battery 13 side of the parallel relay 32 on the parallel connection line 15. The switching circuit 30 connects the first and second batteries 12 and 13 in series with each other by turning off the parallel relays 31 and 32 and turning on the series relay 33. The switching circuit 30 also connects the first and second batteries 12 and 13 in parallel with each other by turning on the parallel relays 31 and 32 and turning off the series relay 33. The parallel relays 31 and 32 and the series relay 33 are controlled by the ECU 70.

[0012] The charging device 40 includes charging circuits 42 and 44. The charging circuits 42 and 44 are connected to the inverter 22 side of the system main relay SMR of the positive line 14a and the negative line 14b of the power line 14 via relays (charging relays) 60 and 62. The charging circuit 42 is connected to the second battery 13 side of the parallel relay 31 of the positive line 14a and to the second battery 13 side of the parallel relay 32 of the parallel connection line 15 via a relay 66. As shown in FIG. 2 , the charging circuit 42 includes a noise filter NF42, a power factor correction circuit (PFC) 42a, a smoothing capacitor C42, and a DC / DC converter (voltage conversion circuit) 42b. The noise filter NF42 is configured as a well-known noise filter that suppresses noise from entering from the external power supply EPS and noise from leaving the external power supply EPS. Smoothing capacitor C42 smoothes the voltage of power line PL42 connecting PFC 42a and DC / DC converter 42b. DC / DC converter 42b is configured as a bidirectional DC / DC converter that converts DC power into DC power of a different voltage. PFC 42a and DC / DC converter 42b form a bidirectional converter that converts AC power from noise filter NF42 into DC power of a desired voltage and converts DC power from charging line PLc into AC power. When connector 46 connected to external power line PLe is connected to connector Cn connected to external power supply EPS and relay 60 is on, charging circuit 42 converts AC power supplied from external power supply EPS via connectors Cn, 46, and external power line PLe into DC power and supplies it to first and second batteries 12, 13 via charging line PLc and relay 60 to charge first and second batteries 12, 13. Furthermore, when connector 46 and connector Cn are connected and relay 60 is on, charging circuit 42 converts DC power input from first and second batteries 12, 13 via relay 60 and charging line PLc into AC power and supplies the power to a load (not shown) on the external power supply EPS side via external power line PLe, connectors 46, and Cn.The charging circuit 44 is connected to the first battery 12 side of the parallel relay 31 of the positive electrode line 14a and to the second battery 13 side of the parallel relay 32 of the parallel connection line 15 via a relay 64. The charging circuit 44 has the same configuration as the charging 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 connected to the external power line PLe and the connector Cn connected to the external power supply EPS are connected and the relay 62 is on, the charging circuit 44 converts AC power supplied from the external power supply EPS via the connectors Cn, 46, and the external power line PLe into DC power and supplies it to the first and second batteries 12, 13 via the charging line PLs and the relay 62 to charge the first and second batteries 12, 13, or converts DC power input from the first and second batteries 12, 13 via the relay 62 and the charging line PLs into AC power and supplies it to a load (not shown) on the external power supply EPS side via the external power line PLe, connectors 46, and Cn.

[0013] ECU 70 is configured as a microcomputer centered around a CPU. Signals are input to ECU 70 from various sensors. The various sensors include voltage V1 from voltage sensor 42d that detects the output voltage of charging circuit 42 and voltage V2 from voltage sensor 44d that detects the input voltage of charging circuit 44. ECU 70 outputs control signals to inverter 22, switching circuit 30 (parallel relays 31 and 32, series relay 33), charging circuits 42 and 44, relay 60, relay 62, and relays 64 and 66.

[0014] In the power supply system 10, when the connector 46 and the connector Cn are connected, the ECU 70 selects parallel charging or series charging when the voltage V1 from the voltage sensor 42d is equal to the first or second voltage Vs1 or Vs2 with the system main relay SMR and the relay 60 or the relay 62 turned on. In parallel charging, the first and second batteries 12 and 13 are connected in parallel from the perspective of the connector 46 by turning off the series relay 33 and the relays 64 and 66 and turning on the parallel relays 31 and 32, and the first and second batteries 12 and 13 are charged using power from the external power supply EPS. In series charging, the series relay 33 is turned on and the parallel relays 31 and 32 and the relays 64 and 66 are turned off, and the first and second batteries 12 and 13 are connected in series from the perspective of the connector 46, and the first and second batteries 12 and 13 are charged using power from the external power supply EPS. When the connector 46 and the connector Cn are connected, and the system main relay SMR and the relay 60 or the relay 62 are turned on, the ECU 70 selects parallel power feeding or series power feeding when the voltage V2 from the voltage sensor 44d is the first or second voltage Vs1 or Vs2. In parallel power feeding, the series relay 33 and the relays 64 and 66 are turned off and the parallel relays 31 and 32 are turned on, thereby connecting the first and second batteries 12 and 13 in parallel from the connector 46 and feeding power from the first and second batteries 12 and 13 to the external power source EPS. In series power feeding, the series relay 33 is turned on and the parallel relays 31 and 32 and the relays 64 and 66 are turned off, thereby connecting the first and second batteries 12 and 13 in series from the connector 46 and feeding power from the first and second batteries 12 and 13 to the external power source EPS.

[0015] Next, the operation of the power supply system 10 according to the embodiment, particularly the operation when turning off the parallel relay 31, will be described. During parallel charging or parallel power supply, the system main relay SMR is on, and either the relay 60 or the relay 62 is on. The series relay 33, the relays 64, and the relays 66 are off, and the parallel relays 31 and 32 are on. If the connector Cn is removed from the connector 46 during parallel charging or parallel power supply, the ECU 70 turns off the relays 60 and 62 that are on. Then, before turning off the parallel relays 31 and 32, the ECU 70 turns on the relays 64 and 66 to execute pre-off control, which controls the DC / DC converter 42b of the charging circuit 42 and the DC / DC converter 44b of the charging circuit 44 so that the voltage V1 from the voltage sensor 42d and the voltage V2 from the voltage sensor 44d are equal. FIG. 3 is an explanatory diagram illustrating an example of a current path when the pre-off control is executed. In the diagram, bold lines indicate current paths. As shown in the figure, the current path for the pre-off control runs from the first battery 12 through the positive line 14a, the positive side of the relay 64, the positive side of the charging circuit 44 (charging line PLs, positive line of the power line PL44), the positive line of the external power line PLe, the positive side of the charging circuit 42 (charging line PLc, positive line of the power line PL42), the positive side of the relay 66, the positive line 14a, the second battery 13, the negative side of the relay 66, the negative side of the charging circuit 42 (charging line PLc, negative line of the power line PL42), the negative line of the external power line PLe, the negative side of the charging circuit 44 (charging line PLs, negative line of the power line PL44), the negative side of the relay 64, the parallel connection line 15, and the negative side of the parallel relay 32 to the first battery 12. At this time, voltage V1 from voltage sensor 42d is the voltage on the second battery 13 side of parallel relay 31, and voltage V2 from voltage sensor 44d is the voltage on the first battery 12 side of parallel relay 31. Therefore, the pre-off control is a control that equalizes the voltages across parallel relay 31. Then, when voltage V1 from voltage sensor 42d and voltage V2 from voltage sensor 44d become equal during the pre-off control, the pre-off control is terminated, and relays 64, 66 are turned off, and parallel relays 31, 32 are turned off.Since the parallel relay 31 is turned off after the voltages across the parallel relay 31 are equalized, it is possible to protect the parallel relay 31. Furthermore, in the pre-off control, the DC / DC converters 42b, 44b of the charging circuits 42, 44 are controlled so that the voltage V1 from the voltage sensor 42d and the voltage V2 from the voltage sensor 44d are equalized, so that the voltages across the parallel relay 31 can be equalized relatively quickly and the parallel relay 31 can be turned off. This makes it possible to shorten the time required for parallel charging (the time from the start to the end of parallel charging) and perform more appropriate control.

[0016] In the power supply system 10 of the embodiment described above, more appropriate control can be achieved by controlling the relays 60, 62, 64, 66, and the charging device 40 so that the voltages across the parallel relay 31 are adjusted to be equal with the on-state relays of the relays 60 and 62 turned off and the relays 64 and 66 turned on.

[0017] In the above-described embodiment, charging device 40 includes charging circuits 42 and 44 shown in Fig. 2 , but may include only one of charging circuits 42 and 44. For example, when charging device 40 includes only charging circuit 44, the positive line of power line PL44 shown in Fig. 2 may be connected to the second battery 13 side of parallel relay 31 of positive line 14a via the positive side of relay 66, and the negative line of power line PL44 may be connected to the second battery 13 side of parallel relay 32 of parallel connection line 15 via relay 66, and DC / DC converter 44b may be controlled so that the voltage across parallel relay 31, i.e., voltage V2 from voltage sensor 44d, and voltage Vc of smoothing capacitor C44 become equal.

[0018] In the above-described embodiment, before turning off 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 circuits 42 and 44 so that the voltage V1 from the voltage sensor 42d and the voltage V2 from the voltage sensor 44d become equal. However, when the temperatures of the first and second batteries 12, 13 are low, such as when the vehicle is cold, more appropriate control may be performed to raise the temperatures of the first and second batteries 12, 13 by alternately repeating a first control in which relays 60, 62 are turned off and parallel relays 31, 32 and relays 64, 66 are turned on to control the DC / DC converters 42b, 44b of the charging circuits 42, 44 so that the voltage V1 from the voltage sensor 42d is higher than the voltage V2 from the voltage sensor 44d, and a second control in which the DC / DC converters 42b, 44b of the charging circuits 42, 44 are controlled so that the voltage V1 from the voltage sensor 42d is lower than the voltage V2 from the voltage sensor 44d.

[0019] In the above embodiment, charging device 40 is connected to both ends of parallel relay 31, and the voltage across parallel relay 31 is adjusted. However, the relay across which charging device 40 is connected may be any relay as long as there is a concern that a current will flow due to a voltage difference across the relay when it is turned off, and may be parallel relay 32, series relay 33, system main relay SMR, or the like. In this case, adjusting the voltage across the relay to which charging device 40 is connected allows for more appropriate control.

[0020] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Explanation of symbols]

[0021] 10 power supply system, 30 switching circuit, 70 electronic control unit (ECU).

Claims

[Claim 1] a first battery connected to the power line; a second battery connected to the positive electrode line of the power line and connected to the negative electrode line of the power line via a parallel connection line; a switching circuit having a plurality of relays and switching the connection between the first battery and the second battery between a series connection and a parallel connection; a charging device having a voltage conversion circuit that exchanges power between an external power line to which power from an external power source is supplied and a charging line, while converting the voltage; a system main relay attached to the power line; a charging relay attached to the charging line; a control device that controls the switching circuit, the charging device, and the charging relay; A power supply system comprising: the charging device is connected to both ends of a target relay as one relay among the plurality of relays of the switching circuit and the system main relay via first and second relays; The control device controls the charging relay, the first and second relays, and the charging device so that the voltage across the target relay is adjusted with the charging relay turned off and the first and second relays turned on. Power supply system.

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