Power supply system

Abstract

To suppress a comparatively large deviation between a charging current of a first battery and a charging current of a second battery in parallel charging.SOLUTION: When the upper limit power of the charging facility is less than the total required power during parallel charging, the first inverter and the second inverter are controlled using power based on the common required power, power obtained by subtracting a correction amount from the current command of the second battery, or the current command. As a result, it is possible to suppress a relatively large deviation between the charging current of the first battery and the charging current of the second battery during parallel charging.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, a power supply system has been proposed that includes a storage battery device having a first battery and a second battery and a switching relay that can switch between a first state in which the first battery and the second battery are connected in series and a second state in which the second battery are connected in parallel, and an inlet connected to a positive line and a negative line that connect the storage battery device and 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 a first battery, a second battery, and a charging connector, and that are capable of parallel charging, in which the first battery is charged via a first charging path and the second battery is charged via a second charging path using power from a charging facility connected to the charging connector.In such power supply systems, there is a possibility that the charging current of the first battery and the charging current of the second battery will differ relatively significantly during parallel charging.

[0005] The power supply system of the present disclosure has as its main objective to prevent a relatively large deviation between the charging current of the first battery and the charging current of the second battery during parallel charging. [Means for solving the problem]

[0006] 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 a first battery and a second battery, 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 first allowable input power of the first battery and a second allowable input power of the second battery during parallel charging in which the first battery and the second battery are charged using power from the charging facility. a control device that sets a minimum value of the input power to a common required power of the first battery and the second battery, sets an overall required power based on the common required power, requests the charging equipment to provide the overall required power or an overall required current based on the overall required power, controls the first inverter and the second inverter using the common required power or a current command for the second battery based on the common required power, and when the upper limit power of the charging equipment during parallel charging is less than the overall required power, controls the first inverter and the second inverter using power based on the common required power or a current command obtained by subtracting a correction amount from the current command for the second battery. [Brief explanation of the drawings]

[0007] [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

[0008] 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 stand 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 motor 20, first and second inverters 22, 24, a switching circuit 30, a charging circuit 40, and an electronic control unit (system ECU, control device) 50. The power supply system 10 is capable of charging the battery 12 using electric power from a charging stand (charging equipment) 80 installed at a home, a charging station, or the like.

[0009] The battery 12 includes first and second batteries 13 and 14. The first and second batteries 13 and 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 and 14 are connected in series to each other.

[0010] 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.

[0011] 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, 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 allowable input powers Win1, Win2. The allowable input powers Win1, Win2 are calculated based on the power storage rates SOC1, SOC2 and the temperatures Tb1, Tb2, and are set to decrease as the temperatures Tb1, Tb2 decrease relative to the lower limit of the normal temperature range. The system ECU 50 outputs control signals to the first and second inverters 22, 24, the series relay Rs, and the first and second parallel relays Rp1, Rp2. The system ECU 50 is capable of communicating with an electronic control unit (stand ECU) 86 of the charging stand 80 .

[0012] 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 into DC power within a range not exceeding the upper limit power Psmax and adjusts the output power (output voltage and output current) and outputs the adjusted power to the stand connector 82 side, and a stand ECU 86. The upper limit power Psmax is power that is determined in advance through experiments, analysis, and machine learning as the upper limit of power that can be supplied from the charging stand 80. Signals from various sensors are input to the stand ECU 86. A control signal to the power supply device 84 is output from the stand ECU 86. As described above, the stand ECU 86 is capable of communicating with the system ECU 50. Examples of charging stations 80 include a first voltage station where the voltage of the supplied power is a first voltage Vs1 (e.g., 400 V), a second voltage station where the voltage of the supplied power 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 supplied power can be selectively set to either the first voltage Vs1 or the second voltage Vs2.

[0013] 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 current that flows in this 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 line 36 (first parallel relay Rp1), 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 current that flows in this 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 (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, 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. Also, the upper arm of the first inverter 22 is fixed on and the upper and lower arms of the second inverter 24 are duty controlled, so that the motor 20 and the second inverter 24 function as a three-phase step-up converter. In series charging, the series relay Rs is set to the on state and the first and second parallel relays Rp1, Rp2 are set to the off state, so that the first and second batteries 13, 14 are connected 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.

[0014] Next, the operation of the power supply system 10 according to the embodiment, particularly the operation during parallel charging, will be described. Figure 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.

[0015] When this routine is executed, the system ECU 50 first sets the minimum value of the allowable input powers Win1 and Win2 of the first and second batteries 13 and 14 as a common required power Pb*, which is the required power common to the first and second batteries 13 and 14 (S100). Next, the system ECU 50 sets a corrected required power Pb1* of the first battery 13 by feedback correction to cancel out the difference between the common required power Pb* and the charging power Pb1 of the first battery 13 (S110), and sets a corrected required power Pb2* (=Pb*+PI(Pb2,Pb*)) of the second battery 14 by feedback correction to cancel out the difference between the common required power Pb* and the charging power Pb2 ​​of the second battery 14 (S120). Here, the charging power Pb1 is calculated, for example, by multiplying the voltages Vb1, Vb2 of the first and second batteries 13, 14 by the currents Ib1, Ib2 (the currents Ip1, Ip2 flowing through the first and second positive lines 31, 32). The sum of the corrected required powers Pb1*, Pb2* is then set as the total required power Pt* (S130), and it is determined whether this is less than the upper limit power Psmax of the charging stand 80 (S140). The upper limit power Psmax is input from the stand ECU 86 via communication.

[0016] If the upper limit power Psmax is equal to or greater than the total required power Pt* in S140, it is determined that power sufficient to cover the total required power Pt* can be supplied from the charging stand 80 to the stand connector 82, and a total required current It* is set based on the set total required power Pt* and transmitted to the stand ECU 86 of the charging stand 80 (S170). 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 stand ECU 86 controls the power supply device 84 so that a current equivalent to the total required current It* is supplied from the charging stand 80 to the power supply system 10. Then, a current command Ib2* for the second battery 14 is set based on the corrected required power Pb2* (S180), and the first and second inverters 22, 24 are controlled based on the set current command Ib2* (S190), after which this routine ends. The current command Ib2* is calculated, for example, by dividing the corrected required power Pb2* by the voltage Vb2 of the second battery 14. This process prevents the charging powers Pb1, Pb2 of the first and second batteries 13, 14 from continuing to exceed the allowable input powers Win1, Win2, thereby preventing the deterioration of the first and second batteries 13, 14 from progressing.

[0017] If it is determined in S140 that the upper limit power Psmax is less than the total required power Pt*, it is determined that the charging stand 80 cannot supply enough power to cover the total required power Pt* to the stand connector 82, and the corrected required power Pb2* is reset by subtracting a correction amount Pbc from the power (=Pb*+PI(Pb2, Pb*)) set by feedback correction to cancel out the difference between the common required power Pb* and the charging power Pb2 ​​(S150). Here, the correction amount Pbc may be the power obtained by subtracting the charging power Pb1 of the first battery 13 from the common required power Pb*, or it may be a predetermined constant value. The sum of the corrected required powers Pb1* and Pb2* is then reset to the total required power Pt* (S160). Therefore, the total required power Pt* is reset to a power smaller than the total required power Pt* set in S130. Then, the total required current It* is set based on the reset total required power Pt* and transmitted to the station ECU 86 of the charging station 80 (S170). Furthermore, a current command Ib2* is set based on the corrected required power Pb2* (S180), and the first and second inverters 22, 24 are controlled based on the set current command Ib2* (S190), after which the routine ends. When the upper limit power Psmax is less than the total required power Pt*, if S170 and subsequent steps are executed without executing S150 and S160, the second battery 14 is charged with the corrected required power Pb2*, and the first battery 13 is charged with power obtained by subtracting the corrected required power Pb2* from the upper limit power Psmax. Therefore, there is a possibility that the charging current of the first battery 13 and the charging current of the second battery 14 will differ significantly. In this embodiment, when the upper limit power Psmax is less than the total required power Pt*, the corrected required power Pb2* (=Pb*+PI(Pb2,Pb*)-Pbc) is reset in S150 to be smaller than the corrected required power Pb2* set in S120, and the first and second inverters 22, 24 are controlled based on the current command Ib2* that is set using the reset corrected required power Pb2*. This reduces the charging current of the second battery 14 and increases the charging current of the first battery 13, making it possible to prevent a relatively large deviation between the charging current of the first battery 13 and the charging current of the second battery 14.

[0018] In the power supply system 10 of the present embodiment described above, when the upper limit power Psmax is less than the total required power Pt* during parallel charging, the first and second inverters 22, 24 are controlled using power based on the common required power Pb* minus the correction amount Pbc, thereby preventing a relatively large deviation between the charging current of the first battery 13 and the charging current of the second battery 14.

[0019] In the above-described embodiment, when the upper limit power Psmax is less than the total required power Pt*, S150 to S190 are executed. However, S170 may be executed without executing S150 and S160, and instead of S180, the current command Ib2* may be set to the current value based on the corrected required power Pb2* minus the correction amount Ibc, and S190 may be executed.

[0020] In the above-described embodiment, S110 and S120 are executed. However, S110 and S120 may not be executed, and the total required power Pt* may be set to twice the common required power Pb* in S130. In this case, if the upper limit power Psmax is less than the total required power Pt*, S150 may not be executed, and S160 may be performed without executing S170 to S190, in which case the total required power Pt* may be reset to the power obtained by subtracting the correction amount Pbc from twice the common required power Pb*.

[0021] 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. [Explanation of symbols]

[0022] 10 power system, 13 first battery, 14 second battery.

Claims

[Claim 1] A power supply system including a first battery and a second battery, 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 device; a control device that, during parallel charging in which the first battery and the second battery are charged using power from the charging equipment, sets the minimum of the first allowable input power of the first battery and the second allowable input power of the second battery to a common required power of the first battery and the second battery, sets an overall required power based on the common required power, requests the charging equipment to provide the overall required power or an overall required current based on the overall required power, and controls the first inverter and the second inverter using the common required power or a current command for the second battery based on the common required power, and when the upper limit power of the charging equipment during parallel charging is less than the overall required power, controls the first inverter and the second inverter using power based on the common required power or a current command obtained by subtracting a correction amount from the current command for the second battery; A power supply system comprising:

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