Power supply system

Abstract

The power supply system of the present disclosure suppresses an increase in the difference between the required power and the charging power of the first and second batteries.SOLUTION: During parallel charging, the power supply system sets a minimum value of a first allowable input power of the first battery and a second allowable input power of the second battery to a common power requirement of the first battery and the second battery. Setting a first corrected required power of the first battery by performing a feedback correction based on a difference between the common required power and the charging power of the first battery, setting a second corrected required power of the second battery by performing a feedback correction based on a difference between the common required power and the charging power of the second battery, requesting a sum of the first corrected required power and the second corrected required power from the charging facility, and controlling the first inverter and the second inverter using a current command of the second battery based on the second corrected required power or the corrected required power of the second battery.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, during parallel charging, there may be a discrepancy between the power required by the first and second batteries and the charging power of the first and second batteries due to losses in the first and second charging paths, etc. The power supply system disclosed herein primarily aims to prevent this discrepancy from becoming too large between the power required by the first and second batteries and the charging power. [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 a first battery and a second battery, comprising: 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 configured to charge the first battery and the second battery in parallel using power from the charging facility, the power supply system including: 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 charging connector connected to the first positive line and the negative line and electrically connectable to a charging facility; and the second battery as a common required power, perform feedback correction based on the difference between the common required power and the charging power of the first battery to set a first corrected required power of the first battery, perform feedback correction based on the difference between the common required power and the charging power of the second battery to set a second corrected required power of the second battery, set the sum of the first corrected required power and the second corrected required power to an overall required power, request the charging equipment to provide an overall required current based on the overall required power or the second corrected required power, and control the first inverter and the second inverter using the second corrected required power or a current command for the second battery based on the second corrected required power. With this configuration, it is possible to prevent a large deviation between the required power and the charging power of the first and second batteries. [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] 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) 50. The power supply system 10 is capable of charging the battery 12 using electric power from a charging stand 80 installed at a home, a charging station, or the like.

[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 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.

[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 the power storage rates SOC1, SOC2 and the temperatures Tb1, Tb2, and are set to decrease as the temperatures Tb1, Tb2 become lower 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.

[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 a first voltage stand that supplies power at a first voltage Vs1 (e.g., 400 V), a second voltage stand that supplies power at a second voltage Vs2 (e.g., 800 V) that is higher than the first voltage Vs1, and a third voltage stand that can selectively set the supply power voltage to either the first voltage Vs1 or the second voltage 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 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.

[0013] 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.

[0014] 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, 14 as a common required power Pb*, which is the required power common to the first and second batteries 13, 14 (step 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 (step S110), and sets a corrected required power Pb2* 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 (step S120). Here, the charging power Pb1 of the first and second batteries 13, 14 is calculated, for example, by multiplying the voltage Vb1 of the first and second batteries 13, 14 by the currents Ib1, Ib2 (currents Ip1, Ip2 flowing through the first and second positive electrode lines 31, 32).

[0015] The sum of the corrected power requirements Pb1* and Pb2* of the first and second batteries 13, 14 is then set as the total power requirement Pt* (step S130), and the total current requirement It* is set based on the set total power requirement Pt* and transmitted to the stand ECU 86 of the charging stand 80 (step S140). The total current requirement It* is calculated, for example, by dividing the total power requirement Pt* by the output voltage Vs of the power supply device 84, or by dividing the total power requirement Pt* by the maximum value of the voltages Vb1 and Vb2 of the first and second batteries 13, 14. Upon receiving the total current requirement It*, the stand ECU 86 controls the power supply device 84 so that a current equivalent to the total current requirement 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* (step S150), and the first and second inverters 22, 24 are controlled based on the set current command Ib2* (step S160), 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. Due to losses in the motor 20 or the first and second inverters 22, 24, there may be a deviation between the common required power Pb* for the first and second batteries 12, 14 and the charging powers Pb1 and Pb2. In contrast, by the above-described process, for example, when the charging powers Pb1, Pb2 of the first and second batteries 13, 14 are greater than the common required power Pb*, the corrected required powers Pb1*, Pb2* of the first and second batteries 13, 14 become smaller than the common required power Pb*, the total required power Pt* becomes smaller than twice the common required power Pb*, the power from the charging stand 80 becomes smaller, and the charging powers Pb1, Pb2 become smaller (approach the common required power Pb*). As a result, it is possible to prevent the deviation between the common required power Pb* of the first and second batteries 13, 14 and the charging powers Pb1, Pb2 from becoming larger.

[0016] In the power supply system 10 of the embodiment described above, during parallel charging, first, the minimum value of the allowable input powers Win1 and Win2 of the first and second batteries 13 and 14 is set as the common required power Pb* of the first and second batteries 13 and 14. Next, feedback correction is performed based on the difference between the common required power Pb* and the charging powers Pb1 and Pb2 of the first and second batteries 13 and 14 to set the corrected required powers Pb1* and Pb2* of the first and second batteries 13 and 14. The sum of the corrected required powers Pb1* and Pb2* is then set as the total required power Pt*, and a total required current It* based on the total required power Pt* is requested of the charging stand 80. The first and second inverters Pb2* are controlled using a current command Ib* for the second battery 14 based on the corrected required power Pb2*. By this control, it is possible to prevent the deviation between the common required power Pb* of the first and second batteries 13, 14 and the charging powers Pb1, Pb2 from becoming too large.

[0017] In the above-described embodiment, the total required current It* based on the total required power Pt* is transmitted to the station ECU 86 during parallel charging, but this is not limited to this. For example, the total required power Pt* may be transmitted to the station ECU 86 during parallel charging. In this case, upon receiving the total required power Pt*, the station ECU 86 controls the power supply device 84 so that power equivalent to the total required power Pt* is supplied from the charging station 80 to the power supply system 10.

[0018] In the above-described embodiment, the first and second inverters Pb2* are controlled using the current command Ib* of the second battery 14 based on the corrected required power Pb2* during parallel charging, but this is not limiting. For example, during parallel charging, the step-down control or step-up control may be performed directly using the corrected required power Pb2* (without using the current command Ib2*).

[0019] 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]

[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 system ECU.

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; During parallel charging in which the first battery and the second battery are charged using power from the charging facility, a common required power for the first battery and the second battery is set to the minimum of a first allowable input power of the first battery and a second allowable input power of the second battery, a feedback correction based on the difference between the common required power and the charging power of the first battery is performed to set a first corrected required power for the first battery, and a feedback correction based on the difference between the common required power and the charging power of the second battery is performed to set a second corrected required power for the second battery, a sum of the first corrected required power and the second corrected required power is set to a total required power, a total required current based on the total required power or the total required power is requested of the charging facility, and the first inverter and the second inverter are controlled using a current command for the second battery based on the second corrected required power or the second corrected required power. Power supply system.

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