Power supply system

Abstract

To suppress overcurrent.SOLUTION: In a case where an upper arm of one of the first inverter and the second inverter is fixed to an ON state during parallel charging / powering in which the first battery and the second battery are charged with electric power from the charging / powering facility or electric power is supplied from the first battery and the second battery to the charging / powering facility, when a difference between a post-change current value obtained by slowly changing the current value of the second battery and the current value of the first inverter or the second inverter is equal to or larger than a predetermined difference, the upper arm of one of the first inverter and the second inverter is fixed to ON, and the upper arm and the lower arm of the other are duty-controlled based on a current command.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, charging the first and second batteries via first and second charging paths using power from a charging facility connected to the charging connector. In such power supply systems, overcurrents can occur in the power supply system due to factors such as power fluctuations in the charging facility or an open-circuit voltage difference between the first and second batteries. The power supply system disclosed herein primarily aims to suppress overcurrents. [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.

[0006] The power supply system of the present disclosure comprises: 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, when an upper arm of one of the first and second inverters is fixed on during parallel charging and power supply in which the first and second batteries are charged using power from the power charging equipment or power is supplied to the power charging equipment using power from the first and second batteries, fixes the upper arm of one of the first and second inverters on and duty controls the upper arm and lower arm of the other inverter based on a current command when a difference between a current value after slowly changing a current value of the second battery and a current value of the first inverter or the second inverter is equal to or greater than a predetermined difference; The gist of the project is to provide the following:

[0007] The power supply system disclosed herein can suppress overcurrent by having the above-described configuration. [Brief explanation of the drawings]

[0008] [Figure 1] 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. [Figure 2] FIG. 4 is an explanatory diagram showing the flow of current during parallel charging. [Figure 3] 4 is a flowchart showing an example of a processing routine executed by a system ECU 50. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] In the power supply system 10, when the charging connector 44 and the stand connector 82 are connected, the system ECU 50 selects parallel charging or series charging when the voltages of the charging power or the power supplied from the charging stand 80 are first and second voltages Vs1 and Vs2, respectively. In parallel charging, the series relay Rs is turned off and the first and second parallel relays Rp1 and Rp2 are turned on, thereby connecting the first and second batteries 13 and 14 in parallel from the charging connector 44. This allows the first and second batteries 13 and 14 to be charged using power from the charging stand 80, or power to be supplied to the charging stand 80 using power from the first and second batteries 13 and 14. FIG. 2 is an explanatory diagram showing the current flow during parallel charging. In the figure, thick solid lines and thick dashed lines with arrows indicate the current paths of the charging current for the first and second batteries 13 and 14, respectively. In parallel charging, the first battery 13 is charged by a 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 current path indicated by the thick solid arrow in Fig. 2. The second battery 14 is charged by a 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 current path indicated by the thick dashed arrow in Fig. 2. The current flow during parallel power feeding is opposite to that during parallel charging. At this time, by fixing the upper arm of second inverter 24 to ON (fixing the lower arm to OFF) and duty controlling the upper and lower arms of first inverter 22, motor 20 and first inverter 22 function as a three-phase step-down converter, and the input power of first inverter 22 is stepped down and output from motor 20 (step-down control).Furthermore, 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 boost converter, and the input power of the motor 20 is boosted and output from the second inverter 24 (boost control). In series charging and power supply, the first and second batteries 13, 14 are connected in series by turning the series relay Rs on and the first and second parallel relays Rp1, Rp2 off, and the first and second batteries 13, 14 are charged using power from the charging station 80, or power is supplied to the charging station 80 using power from the first and second batteries 13, 14. In series charging, the first and second batteries 13, 14 are charged by a 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 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. The current flow in series power supply is opposite to the current flow in series charging.

[0015] Next, the operation of the power supply system 10 according to the embodiment, particularly the operation during parallel charging and supplying, will be described. Fig. 3 is a flowchart showing an example of a processing routine executed by the system ECU 50. This routine is repeatedly executed at predetermined time intervals (e.g., every few msec) when the upper arms of the first and second inverters 22, 24 are fixed on (the lower arms are fixed off) during parallel charging and supplying. Before starting this routine, the system ECU 50 turns off the series connection relay Rs and turns on the first parallel connection relay Rp1 and the second parallel connection relay Rp2, and transmits to the stand ECU 86 a charging upper limit current Iinmax, which is the current with the smaller absolute value among currents obtained by dividing the allowable input powers Win1 and Win2 of the first and second batteries 13 and 14, respectively, by the voltages Vb1 and Vb2 of the first and second batteries 13 and 14, and a charging upper limit current Ioutmax, which is the current with the smaller absolute value among currents obtained by dividing the allowable output powers Wout1 and Wout2 by the voltages Vb1 and Vb2 of the first and second batteries 13 and 14, respectively. The stand ECU 86 controls the charging device 84 to supply power within the range of the charging upper limit current Iinmax to the charging connector 44 and to supply power from the charging connector 44 to a device to be powered within the range of the power supply upper limit current Ioutmax.

[0016] 3, the system ECU 50 inputs the currents Ip1 and Ip2 from the current sensors 30i and 32i, the currents Iu, Iv, and Iw from the current sensors 20u, 20v, and 20w, and the current Ip2 input the previous time this routine was executed (previous Ip2) (S100). Then, the system ECU 50 sets a post-change current Ip2t by slowly changing the previous Ip2 toward the current Ip2 input in this routine (S110). The post-change current Ip2t may be set by adding a predetermined change amount ΔIp2 to the previous Ip2 so that the post-change current Ip2t changes from the previous Ip2 toward the current Ip2 input in this routine.

[0017] Next, the inverter current Iinv is calculated as the sum of the input currents Iu, Iv, and Iw (S120). Then, it is determined whether the absolute value AbsI (=|Iinv-Ip2t|) (predetermined difference) of the value obtained by subtracting the post-change current Ip2 from the inverter current Iinv is greater than a threshold value ΔIref (S130). The threshold value ΔIref is a positive value and is used to determine whether the inverter current Iinv is significantly greater than the post-change current Ip2. When an overcurrent flows through the first and second inverters 22 and 24, the inverter current Iinv becomes significantly greater than the post-change current Ip2. Therefore, S130 is a process for determining whether an overcurrent is flowing through the first and second inverters 22 and 24.

[0018] If the absolute value AbsI is smaller than the threshold value ΔIref, it is determined that no overcurrent is flowing through the first and second inverters 22, 24, and the upper arms of the first and second inverters 22, 24 are kept fixed on (the lower arms are kept fixed off) (S140), and this routine is terminated. If the absolute value AbsI is equal to or greater than the threshold value ΔIref, it is determined that an overcurrent is flowing through the first and second inverters 22, 24, and the first and second inverters 22, 24 are duty controlled using the current command Ib2* (S150), and this routine is terminated. The current command Ib2* is the sum of the currents Ip1 and Ip2 divided by 2. The first inverter 22 and the second inverter 24 are controlled, for example, as follows: If the current command Ib2* is lower than the current Ip2, step-down control is performed. If the current command Ib2* is higher than the current Ip2, step-up control is performed. When the current command Ib2* is equal to the input current Ip2, either the step-down control or the step-up control may be executed, or both upper arms of the first inverter 22 and the second inverter 24 may be fixed on (both lower arms may be fixed off). This allows the current of the second battery 14 to be set to the current command Ib2*, and prevents an overcurrent from flowing through the first and second inverters 22, 24.

[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 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, when an upper arm of one of the first and second inverters is fixed on during parallel charging and power supply for charging the first and second batteries using power from the power charging equipment or supplying power to the power charging equipment using power from the first and second batteries, fixes the upper arm of one of the first and second inverters on and duty controls the upper arm and lower arm of the other inverter based on a current command when a difference between a current value after slowly changing a current value of the second battery and a current value of the first inverter or the second inverter is equal to or greater than a predetermined difference; A power supply system comprising:

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