Power supply system

Abstract

To accelerate the temperature rise of a battery on the side where the temperature hardly rises out of first and second batteries.SOLUTION: When charging the first and second batteries using electric power from the charging facility while raising the temperatures of the first and second batteries by the temperature raising device, the power supply system sets a sum of first and second allowable input powers based on first and second temperatures of the first and second batteries to a total required power, requests the total required power or a total required current based on the total required power from the charging facility, and controls the first and second inverters using the second allowable input power or a current command of the second battery based on the second allowable input power.SELECTED DRAWING: Figure 3

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. In such power supply systems, when parallel charging is performed while heating the first and second batteries by circulating a heat transfer medium through the first and second batteries in this order or in the reverse order, it is necessary to promote the temperature rise of the battery that is less likely to rise in temperature, given that the temperature rise of the first and second batteries may differ. The power supply system disclosed herein primarily aims to promote the temperature rise of the battery that is less likely to rise in temperature, out of the first and second batteries. [Means for solving the problem]

[0005] The power supply system of the present disclosure employs the following measures to achieve the above-mentioned main object. The power supply system disclosed herein is a power supply system including first and second batteries, the power supply system including a motor having a three-phase coil, first and second inverters connected to the first and second batteries via first and second positive lines and negative lines and connected to one end and 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, a heating device that circulates a heat medium through the first and second batteries in this order or in the reverse order to raise the temperature of the first and second batteries, and a control device that, when charging the first and second batteries using power from the charging facility while raising the temperature of the first and second batteries with the heating device, sets the sum of first and second allowable input powers based on first and second temperatures of the first and second batteries as a total required power, requests the charging facility to provide either the total required power or a total required current based on the total required power, and controls the first and second inverters using a current command for the second battery based on the second allowable input power or the second allowable input power. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic configuration diagram of a power supply system 10 and a charging stand 80 according to an embodiment. [Figure 2] FIG. 4 is an explanatory diagram showing the flow of current during parallel charging. [Figure 3] 10 is a flowchart illustrating an example of a processing routine. DETAILED DESCRIPTION OF THE INVENTION

[0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram of a power supply system 10 and a charging stand 80 according to an embodiment of the present disclosure. The power supply system 10 is installed in 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 a system ECU 50.

[0008] The battery 12 includes first and second batteries 13 and 14. The first and second batteries 13 and 14 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 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 and 14 are connected in series. The temperature raising device 15 includes a circulation flow path 16, an electric pump 17 that pressure-feeds the heat medium in the circulation flow path 16, and a heating unit 18 that heats the heat medium using a heater. The circulation flow path 16 is a flow path for circulating the heat medium through the electric pump 17, the heating unit 18, the first battery 13, and the second battery 14 in this order.

[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 also 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 electrode line 31 and the negative electrode line 33, and a charging connector 44 connected to the charging line 42 and configured to be connectable to a stand connector 82 of the charging stand 80.

[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 and the allowable input powers Win1, Win2 of the first and second batteries 13, 14. The power storage rates SOC1, SOC2 are calculated based on, for example, the integrated values ​​of the currents Ip1, Ip2 (currents flowing to the first and second batteries 13, 14) flowing through the first and second positive lines 31, 32 when the series relay Rs is in the off state and the first and second parallel relays Rp1, Rp2 are in the on state, and the integrated value of the current Ip1 (currents flowing to the first and second batteries 13, 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, Rp2 are in the off state. The allowable input powers Win1, Win2 are calculated based on, for example, the power storage rates SOC1, SOC2 and the temperatures Tb1, Tb2, and are set to decrease as the temperatures Tb1, Tb2 become lower than the lower limit of the normal temperature range (a predetermined temperature range). The system ECU 50 outputs control signals to the temperature raising device 15, the first and second inverters 22 and 24, the series relay Rs, and the first and second parallel relays Rp1 and Rp2. The system ECU 50 is capable of communicating with a 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 power supply 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 adjusts the output power (output voltage and output current) and outputs the DC power to the stand connector 82, 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 power supply device 84. As described above, the stand ECU 86 is capable of communicating with the system ECU 50. Examples of charging stands 80 include first and second voltage stands that supply power at first and second voltages Vs1 (e.g., 400 V) and Vs2 (e.g., 800 V), respectively, and third voltage stands that can selectively set the supply power voltage to either the first or second voltage Vs1 or Vs2.

[0012] In the power supply system 10, when the charging connector 44 and the stand connector 82 are connected and the voltage of the power supplied by the charging stand 80 is the first or second voltage Vs1 or Vs2, the system ECU 50 selects parallel charging or series charging, respectively. In parallel charging, the first and second batteries 13, 14 are connected in parallel from the perspective of the charging connector 44 by turning off the series relay Rs and turning on the first and second parallel relays Rp1, Rp2, and the first and second batteries 13, 14 are charged using power from the charging stand 80. Figure 2 is an explanatory diagram showing the current flow during parallel charging. In the figure, the thick solid line and thick dashed line with arrows indicate the charging current of the first and second batteries 13, 14, respectively. In parallel charging, the first battery 13 is charged by a current that flows in the following order 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 connection line 36, the negative line 33, the negative line of the charging line 42, and the charging connector 44, as shown by the thick solid line with an arrow in Fig. 2. The second battery 14 is charged by a current that flows in the following order 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, the second battery 14, the negative line 33, the negative line of the charging line 42, and the charging connector 44, as shown by the thick dashed line with an arrow in Fig. 2. At this time, the upper arm of the second inverter 24 is fixed on (the lower arm is fixed off) and the upper and lower arms of the first inverter 22 are duty-controlled, so that the motor 20 and the first inverter 22 function as a three-phase step-down converter. Furthermore, by fixing the upper arm of the first inverter 22 to 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 boost converter. In series charging, the series relay Rs is turned ON and the first and second parallel relays Rp1, Rp2 are turned OFF to connect the first and second batteries 13, 14 in series, and the first and second batteries 13, 14 are charged using power from the charging stand 80.In series charging, the first and second batteries 13, 14 are charged by current that flows in the following order from the charging connector 44 through the positive line of the charging line 42, the first positive line 31, the first battery 13, the series line 35 (series relay Rs), the second battery 14, the negative line 33, the negative line of the charging line 42, and the charging connector 44.

[0013] Next, the operation of the power supply system 10 according to the embodiment will be described, particularly the operation during parallel charging accompanied by heating of the first and second batteries 13, 14 by the heating device 15. In this embodiment, when the lower of the temperatures Tb1, Tb2 of the first and second batteries 13, 14 is below the threshold Tblo, the heating device 15 heats up the first and second batteries 13, 14. The threshold Tblo may be, for example, the lower limit of the normal temperature range or a temperature slightly lower than that. FIG. 3 is a flowchart showing an example of a processing routine repeatedly executed by the system ECU 50 during parallel charging. Before the repeated execution of this routine begins, the series relay Rs is turned off and the first and second parallel relays Rp1, Rp2 are turned on.

[0014] When this routine is executed, the system ECU 50 determines whether the temperature of the first and second batteries 13, 14 is being increased by the temperature increase device 15 (step S100), and if it determines that the temperature of the first and second batteries 13, 14 is not being increased, the system ECU 50 sets the minimum value of the allowable input powers Win1, Win2 of the first and second batteries 13, 14 as the common required power Pb*, which is the power required commonly by the first and second batteries 13, 14 (step S110). Next, the system ECU 50 sets twice the common required power Pb* as the total required power Pt* (step S120), and sets the total required current It* based on the set total required power Pt* and transmits it to the stand ECU 86 (step S130). The total required current It* is calculated, for example, by dividing the total required power Pt* by the output voltage Vs of the power supply device 84, or by dividing the total required power Pt* by the maximum value of the voltages Vb1, Vb2 of the first and second batteries 13, 14. Upon receiving the total required current It*, the station ECU 86 controls the power supply device 84 so that a current equivalent to the total required current It* is supplied from the charging station 80 to the power supply system 10. Then, the station ECU 86 sets a current command Ib2* for the second battery 14 based on the common required power Pb* (step S140), controls the first and second inverters 22, 24 based on the set current command Ib2* (step S150), and ends this routine. In this case, the current command Ib2* is calculated, for example, by dividing the common required power Pb* by the voltage Vb2 of the second battery 14. By controlling the first and second inverters 22, 24 in this way, the second battery 14 is charged with a current equivalent to the current command Ib2* (power equivalent to the common required power Pb*) out of the current equivalent to the total required current It* from the charging stand 80 (power equivalent to the total required power Pt*, i.e., power equivalent to twice the common required power Pb*), and the first battery 13 is also charged with a similar current. Therefore, it is possible to prevent the charging currents of the first and second batteries 13, 14 (currents Ip1, Ip2 flowing through the first and second positive electrode lines 31, 32) from deviating relatively significantly.

[0015] If it is determined in step S100 that the temperature-raising device 15 is currently raising the temperatures of the first and second batteries 13, 14, the allowable input powers Win1, Win2 of the first and second batteries 13, 14 are set to the required powers Pb1*, Pb2* of the first and second batteries 13, 14 (step S160), the sum of the set required powers Pb1*, Pb2* is set to the total required power Pt* (step S170), and the total required current It* is set as in step S130 and transmitted to the stand ECU 86 (step S180). Next, a current command Ib2* for the second battery 14 is set based on the required power Pb2* (step S190), and the first and second inverters 22, 24 are controlled based on the set current command Ib2* (step S200), after which the routine ends. In this case, the current command Ib2* is calculated, for example, by dividing the required power Pb2* by the voltage Vb2 of the second battery 14. By controlling the first and second inverters 22, 24 in this manner, the second battery 14 is charged with a current corresponding to the current command Ib2* (power corresponding to the allowable input power Win2) out of the current corresponding to the total required current It* from the charging stand 80 (power corresponding to the total required power Pt*, i.e., power corresponding to the sum of the required powers Pb1* and Pb2*), and the first battery 13 is charged with a current corresponding to the allowable input power Win1 (power corresponding to the allowable input power Win1). During the heating of the first and second batteries 13, 14 by the temperature-raising device 15, the heat medium flows through the first battery 13 and then the second battery 14, and the temperature Tb1 is likely to be higher than the temperature Tb2, and the allowable input power Win1 is likely to be higher than the allowable input power Win2. Therefore, when the processing of steps S110 to S150 is performed, the first and second batteries 13, 14 are charged with power (current) corresponding to the allowable input power Win2. In contrast, by executing the processing of steps S170 to S200, the first battery 13 is charged with a larger power (current), and the larger heat generated by the first battery 13, in addition to the heat of the heat medium of the temperature raising device 15, can be used to promote the temperature rise of the second battery 14.

[0016] In the above-described embodiment, the temperature raising device 15 may be configured to circulate the heat medium through the second battery 14 and then the first battery 13. In this case, while the temperature raising device 15 is raising the temperatures of the first and second batteries 13, 14, the temperature Tb2 is likely to be higher than the temperature Tb1, and the allowable input power Win2 is likely to be higher than the allowable input power Win1. By performing the processing of steps S170 to S200 of the processing routine in FIG. 3 while the temperature raising device 15 is raising the temperatures of the first and second batteries 13, 14, the second battery 14 is charged with a larger power (current) than when the processing of steps S110 to S150 is performed. This allows the temperature raising of the first battery 13 to be promoted by using the larger heat generated by the second battery 14 in addition to the heat of the heat medium of the temperature raising device 15.

[0017] In the above-described embodiment, during parallel charging, instead of requesting the charging stand 80 for the total required current It* based on the total required power Pt*, the total required power Pt* may be requested from the charging stand 80. Furthermore, during parallel charging, instead of controlling the first and second inverters 22, 24 using a current command Ib2* based on the common required power Pb* or the required power Pb2*, the first and second inverters 22, 24 may be controlled directly using the common required power Pb* or the required power Pb2* (without using the current command Ib2*).

[0018] 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. [Industrial Applicability]

[0019] The present disclosure is applicable to the power supply system manufacturing industry and the like. [Explanation of symbols]

[0020] 10 power supply system, 13 first battery, 14 second battery, 15 temperature control device, 20 motor, 22 first inverter, 24 second inverter, 44 charging connector, 50 system ECU.

Claims

[Claim 1] A power supply system including first and second batteries, a motor having a three-phase coil; first and second inverters connected to the first and second batteries via first and second positive and negative lines and connected to one end and 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 device; a heating device that circulates a heat medium through the first and second batteries in this order or in the reverse order to raise the temperatures of the first and second batteries; a control device that, when charging the first and second batteries using power from the charging equipment while raising the temperatures of the first and second batteries using the temperature raising device, sets the sum of first and second allowable input powers based on the first and second temperatures of the first and second batteries as a total required power, requests the charging equipment to provide the total required power or a total required current based on the total required power, and controls the first and second inverters using the second allowable input power or a current command for the second battery based on the second allowable input power; A power supply system comprising:

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