Power supply system

Abstract

To suppress deviation between a power storage ratio of a first battery and a power storage ratio of a second battery.SOLUTION: In parallel charging / powering in which the first and second batteries are charged with electric power from the charging / powering facility or electric power from the first and second batteries is supplied to the charging / powering facility, when a state of charge of the first battery is equal to a state of charge of the second battery, upper arms of the first and second inverters are fixed to an ON state. When the state of charge of the first battery is lower than the state of charge of the second battery, parallel charging / feeding is performed while charging / feeding the first battery with power from the second battery.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A power supply system has been proposed that includes a storage battery device having first and second batteries and a switching relay that can switch between a first state in which the batteries are connected in series and a second state in which the batteries are connected in parallel, and an inlet connected to positive and negative wires that connect the storage battery device to a PCU that drives a motor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-118221 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, power supply systems have been devised that include first and second batteries and a charging connector, and that are capable of parallel charging, in which the first and second batteries are charged via first and second charging paths using power from a charging facility connected to the charging connector, and power from the first and second batteries is supplied to the charging facility via the first and second charging paths. In such power supply systems, if the charge storage rate of the first battery and the charge storage rate of the second battery differ during parallel charging, unintended current may flow, and therefore it is desirable to suppress this difference. The power supply system disclosed herein primarily aims to suppress the difference between the charge storage rate of the first battery and the charge storage rate of the second battery. [Means for solving the problem]

[0005] The power supply system of the present disclosure employs the following means to achieve the above-mentioned primary object: The power supply system of the present disclosure is a power supply system including first and second batteries, and includes a motor having a three-phase coil, a first inverter connected to the first battery via a first positive line and a negative line and connected to one end of the three-phase coil, a second inverter connected to the second battery via a second positive line and the negative line and connected to the other end of the three-phase coil, a charging connector connected to the first positive line and the negative line and electrically connectable to a charging facility, and a power supply system for charging the first and second batteries using power from the charging facility or for supplying power to the first and second batteries. 1. The present disclosure provides a power supply system including a control device that, during parallel charging and feeding of power to the power feeding equipment using power from a second battery, fixes upper arms of the first and second inverters on when the power storage rate of the first battery and the power storage rate of the second battery are equal, performs the parallel charging while charging the second battery with power from the first battery when the power storage rate of the first battery is higher than the power storage rate of the second battery, and performs the parallel charging while charging the first battery with power from the second battery when the power storage rate of the first battery is lower than the power storage rate of the second battery. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic diagram illustrating the configuration of a power supply system 10 and a charging station 80. [Figure 2] FIG. 10 is an explanatory diagram showing the flow of current during parallel power supply. [Figure 3] FIG. 10 is an explanatory diagram showing the flow of current during parallel power supply. DETAILED DESCRIPTION OF THE INVENTION

[0007] A mode (embodiment) 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 and a charging station 80 according to an embodiment of the present disclosure. The power supply system 10 is mounted on an electric vehicle or a hybrid vehicle, and includes a battery 12, a heating device 15, a motor 20, first and second inverters 22, 24, a switching circuit 30, a charging circuit 40, and an electronic control unit (system ECU) 50 as a control device. The power supply system 10 is capable of charging the battery 12 using power from a charging station (charging facility) 80, and is also capable of supplying power from the battery 12 to the charging station 80.

[0008] The battery 12 includes first and second batteries (first and second cells) 13, 14. The first and second batteries 13, 14 are configured as secondary batteries with identical specifications and a rated voltage slightly lower than the first voltage Vs1 (e.g., 400 V). The positive terminal of the first battery 13 is connected to a first positive line 31, and the negative terminal of the second battery 14 is connected to a negative line 33. The negative terminal of the first battery 13 is connected to the positive terminal of the second battery 14 via a series line 35 to which a series relay Rs is attached. By turning on the series relay Rs, the first and second batteries 13, 14 are connected in series to each other.

[0009] The motor 20 includes, for example, a rotor with a permanent magnet embedded in a rotor core and a stator with three-phase (U-phase, V-phase, and W-phase) coils wound around a stator core. The first and second inverters 22 and 24 include six transistors T11-T16 and T21-T26 as switching elements, and six diodes D11-D16 and D11-D16 connected in parallel to the six transistors T11-T16 and T21-T26, respectively. The transistors T11-T16 and T21-T26 are arranged in pairs, two at a time, on the source side and two at the sink side with respect to the first and second positive lines 31 and 32 and the negative line 33. The connection points of the paired transistors T11-T16 and T21-T26 are connected to one end and the other end of the three-phase coils of the motor 20, respectively. First and second capacitors 26 and 28 are connected to the first and second positive lines 31 and 32 and the negative line 33, respectively. The transistors T11 to T13 and T21 to T23 may be referred to as the "upper arm," and the transistors T14 to T16 and T24 to T26 may be referred to as the "lower arm." In addition to the first positive line 31, the second positive line 32, the negative line 33, the series line 35, and the series relay Rs, the switching circuit 30 includes a parallel line 36 connecting the negative terminal of the first battery 13 and the negative line 33, a first parallel relay Rp1 attached to the parallel line 36, and a second parallel relay Rp2 attached to the second positive line 32. The charging circuit 40 includes a charging line 42 connected to the first positive line 31 and the negative line 33, and a charging connector 44 connected to the charging line 42 and configured to be connectable to a stand connector 82 of a charging stand 80 installed at a home, a charging station, or the like.

[0010] Signals from various sensors are input to the system ECU 50. These sensors include voltage sensors 13v, 14v and temperature sensors 13t, 14t that detect voltages Vb1, Vb2 and temperatures Tb1, Tb2 of the first and second batteries 13, 14, current sensors 20u, 20v, 20w that detect currents Iu, Iv, Iw flowing through each phase of the motor 20, voltage sensors 26v, 28v that detect voltages VH, VL of the first and second capacitors 26, 28, and current sensors 31i, 32i that detect currents Ip1, Ip2 flowing through the first and second positive lines 31, 32. The system ECU 50 calculates the power storage rates SOC1, SOC2, the allowable input powers Win1, Win2, and the allowable output powers Wout1, Wout2 of the first and second batteries 13, 14. The power storage rates SOC1 and SOC2 are calculated based on, for example, the integrated values ​​of the currents Ip1 and Ip2 (currents flowing to the first and second batteries 13 and 14) flowing through the first and second positive lines 31 and 32 when the series relay Rs is in the OFF state and the first and second parallel relays Rp1 and Rp2 are in the ON state, and the integrated value of the current Ip1 (currents flowing to the first and second batteries 13 and 14) flowing through the first positive line 31 when the series relay Rs is in the ON state and the first and second parallel relays Rp1 and Rp2 are in the OFF state. The allowable input powers Win1 and Win2 are calculated based on the power storage rates SOC1 and SOC2 and temperatures Tb1 and Tb2. The allowable output powers Wout1 and Wout2 are calculated based on the power storage rates SOC1 and SOC2 and temperatures Tb1 and Tb2. The system ECU 50 outputs control signals to the series relay Rs, the first and second parallel relays Rp1 and Rp2, and the first and second inverters 22 and 24. The system ECU 50 is capable of communicating with an electronic control unit (stand ECU) 86 of the charging stand 80.

[0011] The charging stand 80 includes a stand connector 82 configured to be connectable to the charging connector 44 of the power supply system 10, a charging device 84 that converts AC power from an AC power source such as a household power source or a commercial power source into DC power and supplies the DC power to the stand connector 82 side, and converts DC power from the stand connector 82 side into AC power and supplies the AC power to a device to be powered, and a stand ECU 86. Signals from various sensors are input to the stand ECU 86. A control signal is output from the stand ECU 86 to the charging device 84. As described above, the stand ECU 86 is capable of communicating with the system ECU 50. Examples of charging and power supply stations 80 include a first voltage station where the voltage of the charging power or power supply is a first voltage Vs1 (e.g., 400 V), a second voltage station where the voltage of the charging power or power supply is a second voltage Vs2 (e.g., 800 V) that is higher than the first voltage Vs1, and a third voltage station where the voltage of the charging power or power supply can be selectively set to either the first voltage Vs1 or the second voltage Vs2.

[0012] In power supply system 10, when charging connector 44 and stand connector 82 are connected, system ECU 50 selects parallel charging and series charging if the voltages of the charging power or the supplied power from charging stand 80 are first and second voltages Vs1 and Vs2, respectively. In parallel charging and power supply, first and second batteries 13 and 14 are connected in parallel from the perspective of charging connector 44 by turning series relay Rs off and first and second parallel relays Rp1 and Rp2 on, and first and second batteries 13 and 14 are charged using power from charging stand 80, or power is supplied to charging stand 80 using power from first and second batteries 13 and 14.

[0013] In power supply system 10, when charging connector 44 and stand connector 82 are connected, system ECU 50 selects parallel charging and series charging if the voltages of the charging power or the supplied power from charging stand 80 are first and second voltages Vs1 and Vs2, respectively. In parallel charging and power supply, first and second batteries 13 and 14 are connected in parallel from the perspective of charging connector 44 by turning series relay Rs off and first and second parallel relays Rp1 and Rp2 on, and first and second batteries 13 and 14 are charged using power from charging stand 80, or power is supplied to charging stand 80 using power from first and second batteries 13 and 14. In parallel charging, the first battery 13 is charged by current flowing from the charging connector 44 through the positive line of the charging line 42, the first positive line 31, the first battery 13, the parallel line 36 (first parallel relay Rp1), the negative line 33, the negative line of the charging line 42, and the charging connector 44 in that order. The second battery 14 is charged by current flowing from the charging connector 44 through the positive line of the charging line 42, the first positive line 31, the first inverter 22, the motor 20, the second inverter 24, the second positive line 32 (second parallel relay Rp2), the second battery 14, the negative line 33, the negative line of the charging line 42, and the charging connector 44 in that order. The current flow during parallel charging is opposite to the current flow during parallel charging. At this time, by fixing the upper arm of the second inverter 24 on (fixing the lower arm off) and duty controlling the upper and lower arms of the first inverter 22, the motor 20 and the first inverter 22 function as a three-phase step-down converter, and the input power of the first inverter 22 is stepped down and output from the motor 20 (step-down control). Also, by fixing the upper arm of the first inverter 22 on and duty controlling the upper and lower arms of the second inverter 24, the motor 20 and the second inverter 24 function as a three-phase step-up converter, and the input power of the motor 20 is stepped up and output from the second inverter 24 (step-up control). Series charging and power supply is not central to this embodiment, so a description thereof will be omitted.

[0014] Next, the operation of the power supply system 10 according to the embodiment, particularly the operation during parallel power feeding, will be described. Before parallel power feeding begins, the system ECU 50 turns off the series relay Rs and turns on the first parallel relay Rp1 and the second parallel relay Rp2. The system ECU 50 then transmits to the stand ECU 86 a power supply upper limit current Ioutmax, which is the current with the smaller absolute value obtained by dividing the allowable output powers Wout1 and Wout2 of the first and second batteries 13 and 14 by the voltages Vb1 and Vb2 of the first and second batteries 13 and 14. The stand ECU 86 controls the charging device 84 so that power from the charging connector 44 is fed to the device to be powered within the range of the power supply upper limit current Ioutmax.

[0015] When the power storage rate SOC1 of the first battery 13 and the power storage rate SOC2 of the second battery 14 are equal, the system ECU 50 fixes both upper arms of the first and second inverters 22, 24 to ON (fixes both lower arms to OFF). Since the first and second inverters 22, 24 are not switched, no switching loss occurs in the first and second inverters 22, 24, and therefore power supply efficiency can be improved.

[0016] When the power storage rate SOC1 of the first battery 13 is higher than the power storage rate SOC2 of the second battery 14, the system ECU 50 controls the first and second inverters 22, 24 to perform parallel charging and feeding while charging the second battery 14 with power from the first battery 13. Fig. 2 is an explanatory diagram showing the current flow during parallel feeding when the power storage rate SOC1 of the first battery 13 is higher than the power storage rate SOC2 of the second battery 14. In the figure, the thick solid line and thick dashed line with arrows indicate the currents of the first and second batteries 13, 14, respectively. 2, the first battery 13 is supplied with power through the charging connector 44 by current that flows from the first battery 13 through the first positive line 31, the positive line of the charging line 42, the charging connector 44, the negative line of the charging line 42, the parallel line 36 (first parallel relay Rp1), and the first battery 13 in this order. The second battery 14 is charged by current that flows from the first battery 13 through the first positive line 31, the first inverter 22, the motor 20, the second inverter 24, the second positive line 32 (second parallel relay Rp2), the second battery 14, the negative line 33, the parallel line 36 (first parallel relay Rp1), and the first battery 13 in this order. At this time, the first and second inverters 22, 24 may perform either step-down control or step-up control so that the current of the second battery 14 becomes the charging current, or the upper arms of the first inverter 22 and the second inverter 24 may both be fixed on (the lower arms may both be fixed off). Since the second battery 14 is charged with power from the first battery 13, the power storage rate SOC1 decreases and the power storage rate SOC2 increases. This makes it possible to suppress the difference between the power storage rate SOC1 and the power storage rate SOC2.

[0017] When the power storage rate SOC1 of the first battery 13 is lower than the power storage rate SOC2 of the second battery 14, the system ECU 50 controls the first and second inverters 22, 24 to perform parallel charging and feeding while charging the first battery 13 with power from the second battery 14. Fig. 3 is an explanatory diagram showing the current flow during parallel feeding when the power storage rate SOC1 of the first battery 13 is lower than the power storage rate SOC2 of the second battery 14. In the figure, the thick solid line and thick dashed line with arrows indicate the currents of the first and second batteries 13, 14, respectively. As indicated by the thick dashed line with an arrow in Fig. 2, power is supplied to the charging connector 44 by a current that flows from the second battery 14 through the second positive line 32 (second parallel relay Rp2), the second inverter 24, the motor 20, the first inverter 22, the positive line of the charging line 42, the charging connector 44, the negative line of the charging line 42, and the second battery 14 in this order. As indicated by the thick solid line with an arrow in Fig. 3, the first battery 13 is charged by a current that flows from the second battery 14 through the second positive line 32 (second parallel relay Rp2), the second inverter 24, the motor 20, the first inverter 22, the first positive line 31, the first battery 13, the parallel line 36 (first parallel relay Rp1), the negative line 33, and the second battery 14 in this order. At this time, the first and second inverters 22, 24 may perform either step-down control or step-up control so that the current of the second battery 14 becomes the power supply current and the charging current of the first battery 13, or the upper arms of the first inverter 22 and the second inverter 24 may both be fixed on (the lower arms may both be fixed off). Since the first battery 13 is charged with power from the second battery 14, the power storage rate SOC1 increases and the power storage rate SOC2 decreases. This makes it possible to suppress the difference between the power storage rate SOC1 and the power storage rate SOC2.

[0018] In the above embodiment, the present disclosure is described as being applied to operations during parallel power supply, but the present disclosure may also be applied to operations during parallel charging by controlling the first and second inverters 22, 24 so that the above-mentioned current flows are reversed.

[0019] The above describes embodiments for implementing the present disclosure, but the present disclosure is not limited to these embodiments and can, of course, be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0020] The present disclosure is applicable to the power supply system manufacturing industry and the like. [Explanation of symbols]

[0021] 10 power supply system, 13 first battery, 14 second battery, 20 motor, 22 first inverter, 24 second inverter, 44 charging connector, 50 electronic control unit (system ECU).

Claims

[Claim 1] A power supply system including first and second batteries, a motor having a three-phase coil; a first inverter connected to the first battery via a first positive line and a negative line and connected to one end of the three-phase coil; a second inverter connected to the second battery via a second positive line and the negative line and connected to the other end of the three-phase coil; a charging connector connected to the first positive electrode line and the negative electrode line and electrically connectable to a charging equipment; a control device that, during parallel charging and feeding in which the first and second batteries are charged using electric power from the charging equipment or electric power is fed to the charging equipment using electric power from the first and second batteries, fixes upper arms of the first and second inverters on when a power storage rate of the first battery and a power storage rate of the second battery are equal, performs the parallel charging while charging the second battery with electric power from the first battery when the power storage rate of the first battery is higher than the power storage rate of the second battery, and performs the parallel charging while charging the first battery with electric power from the second battery when the power storage rate of the first battery is lower than the power storage rate of the second battery; A power supply system comprising:

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