Power supply system

Abstract

A power supply system suppresses a deviation of a state of charge of a first battery from a state of charge of a second battery. A parallel charging / power-supplying device performs charging of the first and second batteries using the power of the charging / power-supplying device or supplies power to the charging / power-supplying device using the power of the first and second batteries. When the state of charge of the first battery is equal to the state of charge of the second battery, the upper arms of the first and second inverters are fixed to be turned on, and when the state of charge of the first battery is higher than the state of charge of the second battery, parallel charging and feeding are performed while charging and feeding the second battery with power from the first battery. When the state of charge of the first battery is lower than the state of charge of the second battery, parallel charging and feeding are performed while charging and feeding the first battery with power from the second battery.

Description

Technical Field

[0001] This disclosure relates to power supply systems. Background Technology

[0002] Previously, a power supply system was proposed, comprising: an energy storage device having a first battery, a second battery, and a switching relay capable of switching between a first state in which they are connected in series and a second state in which they are connected in parallel; and an input port connected to a positive line and a negative line connected to a PCU that connects the energy storage device to a drive motor (for example, see Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-118221

[0004] In recent years, power supply systems have been proposed that include first and second batteries and a charging power supply connector, enabling parallel charging and power supply to charge the first and second batteries using power from a charging power supply device connected to the charging power supply connector via first and second charging power supply paths, or to supply power from the first and second batteries to the charging power supply device via first and second charging power supply paths. In such power supply systems, if the state of charge (SOC) of the first battery deviates from that of the second battery during parallel charging and power supply, undesirable current may flow, thus suppressing this deviation is desirable. The main objective of the power supply system disclosed herein is to suppress the deviation between the SOC of the first battery and the SOC of the second battery. Summary of the Invention

[0005] To achieve the aforementioned main objectives, the power supply system of this disclosure employs the following means. The power supply system of this disclosure is a power supply system comprising 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 wire and a negative wire, and connected to one end of the three-phase coil; a second inverter connected to the second battery via a second positive wire and the negative wire, and connected to the other end of the three-phase coil; a charging power supply connector connected to the first positive wire and the negative wire, and capable of electrical connection to a charging power supply device; and a control device for charging the first battery and the second battery or using the power from the charging power supply device. When the power from the second battery is used to supply power to the charging power supply device in parallel charging, when the state of charge (SOC) of the first battery is equal to that of the second battery, the upper arms of the first inverter and the second inverter are fixed in the ON position. When the SOC of the first battery is higher than that of the second battery, the parallel charging power supply is performed while charging the second battery using power from the first battery. When the SOC of the first battery is lower than that of the second battery, the parallel charging power supply is performed while charging the first battery using power from the second battery. In the power supply system disclosed herein, the above configuration can suppress the deviation between the SOC of the first battery and the SOC of the second battery. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the power supply system 10 and the charging power supply pile 80.

[0007] Figure 2 It is an explanatory diagram showing the flow of current when power is supplied in parallel.

[0008] Figure 3 It is an explanatory diagram showing the flow of current when power is supplied in parallel.

[0009] Explanation of reference numerals in the attached figures

[0010] 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). Detailed Implementation

[0011] The embodiments (implementations) for carrying out this disclosure will be described with reference to the accompanying drawings. Figure 1 This is a schematic structural diagram of the power supply system 10 and the charging power supply pile 80 according to an embodiment of this disclosure.

[0012] The power system 10 is installed in electric vehicles and hybrid vehicles, and includes a battery 12, a heating device 15, a motor 20, first and second inverters 22 and 24, a switching circuit 30, a charging power supply circuit 40, and an electronic control unit (system ECU) 50 as a control device. The power system 10 can use power from the charging pile (charging power supply equipment) 80 to charge the battery 12, and can also supply power from the battery 12 to the charging pile 80.

[0013] Battery 12 includes first and second batteries 13 and 14. The first and second batteries 13 and 14 are configured as secondary batteries with a rated voltage slightly lower than the first voltage Vs1 (e.g., 400V) and of the same specifications. The positive terminal of the first battery 13 is connected to the first positive line 31, and the negative terminal of the second battery 14 is connected to the 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 equipped with a series relay Rs. By setting the series relay Rs to the ON state, the first and second batteries 13 and 14 are connected in series.

[0014] Motor 20, for example, includes a rotor with permanent magnets embedded in its rotor core and a stator with three-phase (U-phase, V-phase, W-phase) coils wound in its stator core. The first inverter 22 and the second inverter 24 include: six transistors T11-T16 and T21-T26 as switching elements; and six diodes D11-D16 and D11-D16 connected in parallel with the six transistors T11-T16 and T21-T26, respectively. Transistors T11-T16 and T21-T26 are arranged in pairs, with the first and second positive lines 31 and 32 as the source side and the negative line 33 as the drain side. The connection points of the two pairs of transistors T11-T16 and T21-T26 are connected to one end and the other end of the three-phase coils of 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. Transistors T11-13 and T21-T23 are sometimes referred to as the "upper bridge arm," and transistors T14-T16 and T24-T26 are referred to as the "lower bridge arm." In addition to the first positive line 31, second positive line 32, negative line 33, series line 35, and series relay Rs mentioned above, the switching circuit 30 also includes a parallel line 36 connecting the negative terminal of the first battery 13 to the negative line 33, a first parallel relay Rp1 mounted on the parallel line 36, and a second parallel relay Rp2 mounted on the second positive line 32. The charging power supply circuit 40 includes a charging power supply line 42 connected to the first positive line 31 and the negative line 33; and a charging power supply connector 44 connected to the charging power supply line 42, configured to connect to a charging pile connector 82 installed at a charging pile 80 in a home, charging station, etc.

[0015] Signals from various sensors are input to the system ECU 50. Examples of these sensors include voltage sensors 13v and 14v and temperature sensors 13t and 14t that detect the voltages Vb1 and Vb2 and temperatures Tb1 and Tb2 of the first and second batteries 13 and 14, current sensors 20u, 20v, and 20w that detect the currents Iu, Iv, and Iw flowing through each phase of the motor 20, voltage sensors 26v and 28v that detect the voltages VH and VL of the first and second capacitors 26 and 28, and current sensors 31i and 32i that detect the currents Ip1 and Ip2 flowing through the first and second positive lines 31 and 32. The system ECU 50 calculates the states of charge (SOC1 and SOC2) of the first and second batteries 13 and 14, the permissible input power (Win1 and Win2), and the permissible output power (Wout1 and Wout2). The states of charge (SOC1 and SOC2) are calculated, for example, based on the cumulative values ​​of the currents Ip1 and Ip2 (currents flowing through 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 cumulative value of the current Ip1 (current flowing through 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 permissible input powers Win1 and Win2 are calculated based on SOC1 and SOC2 and the temperatures Tb1 and Tb2. The permissible output powers Wout1 and Wout2 are calculated based on SOC1 and SOC2 and the temperatures Tb1 and Tb2. The system ECU50 outputs control signals to the series relay Rs, the first parallel relay Rp1, the second parallel relay Rp2, the first inverter 22, and the second inverter 24.

[0016] The system ECU50 can communicate with the electronic control unit (charger ECU) 86 of the charging pile 80.

[0017] The charging power supply station 80 includes: a station connector 82 configured to connect to a charging power supply connector 44 of the power system 10; a charging power supply device 84 that converts AC power from a power source such as a household power supply or a commercial power supply into DC power and supplies the DC power to the station connector 82 side, or converts the DC power from the station connector 82 side into AC power and supplies the AC power to the target device; and a station ECU 86. Signals from various sensors are input to the station ECU 86. Control signals are output from the station ECU 86 to the charging power supply device 84. As described above, the station ECU 86 is capable of communicating with the system ECU 50. Examples of charging power supply stations 80 include: a first voltage station, wherein the voltage of the charging power or the supply power is a first voltage Vs1 (e.g., 400V); a second voltage station, wherein the voltage of the charging power or the supply power is a second voltage Vs2 (e.g., 800V) higher than the first voltage Vs1; and a third voltage station, which is capable of selectively setting one of the first voltage Vs1 and the second voltage Vs2 to the voltage of the charging power or the supply power.

[0018] In the power system 10, when the charging power supply connector 44 and the charging pile connector 82 are connected to each other, and the voltage of the charging power or supply power of the charging power pile 80 is a first voltage Vs1 and a second voltage Vs2, the system ECU 50 selects parallel charging power supply and series charging power supply respectively. In parallel charging power supply, by setting the series relay Rs to the off state and setting the first and second parallel relays Rp1 and Rp2 to the on state, the first and second batteries 13 and 14 are connected in parallel from the perspective of the charging power supply connector 44, and the charging of the first and second batteries 13 and 14 is performed using the power from the charging power pile 80, and the power from the first and second batteries 13 and 14 is used to supply power to the charging power pile 80.

[0019] In the power system 10, when the charging power supply connector 44 and the charging pile connector 82 are connected to each other, and the voltage of the charging power or supply power of the charging power pile 80 is a first voltage Vs1 and a second voltage Vs2, the system ECU 50 selects parallel charging power supply and series charging power supply respectively. In parallel charging power supply, by setting the series relay Rs to the off state and setting the first and second parallel relays Rp1 and Rp2 to the on state, the first and second batteries 13 and 14 are connected in parallel from the perspective of the charging power supply connector 44, and the charging of the first and second batteries 13 and 14 is performed using the power from the charging power pile 80, and the power from the first and second batteries 13 and 14 is used to supply power to the charging power pile 80. In parallel charging, the first battery 13 is charged by current flowing sequentially from the charging power supply connector 44 through the positive wire of the charging power supply line 42, the first positive wire 31, the first battery 13, the parallel line 36 (first parallel relay Rp1), the negative wire 33, the negative wire of the charging power supply line 42, and the charging power supply connector 44. The second battery 14 is charged by current flowing sequentially from the charging power supply connector 44 through the positive wire of the charging power supply line 42, the first positive wire 31, the first inverter 22, the motor 20, the second inverter 24, the second positive wire 32 (second parallel relay Rp2), the second battery 14, the negative wire 33, the negative wire of the charging power supply line 42, and the charging power supply connector 44. The current flow during parallel power supply is opposite to the current flow during parallel charging. At this time, by fixing the upper arm of the second inverter 24 to be on (and fixing the lower arm to be off) and controlling the duty cycle of the upper and lower arms of the first inverter 22, the motor 20 and the first inverter 22 function as a three-phase buck converter, and the input power of the first inverter 22 is stepped down and output from the motor 20 (buck control). Alternatively, by fixing the upper arm of the first inverter 22 to be on and controlling the duty cycle of 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). Since series charging power supply is not the core of this embodiment, it is omitted from the description.

[0020] Next, the operation of the power system 10 according to the embodiment, particularly its operation during parallel power supply, will be explained. Before starting parallel power supply, the system ECU 50 sets the series relay Rs to the off state and sets the first parallel relay Rp1 and the second parallel relay Rp2 to the on state, sending the upper limit current Ioutmax to the charging ECU 86. This upper limit current Ioutmax is the smaller absolute value of the current obtained by dividing the allowable output power 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, respectively. The charging ECU 86 controls the charging power supply device 84 to supply power from the charging power supply connector 44 to the device to be powered within the upper limit current Ioutmax.

[0021] When the state of charge (SOC1) of the first battery 13 is equal to the state of charge (SOC2) of the second battery 14, the system ECU 50 fixes the upper arms of both the first and second inverters 22 and 24 to be on (and the lower arms to be off). Since the first and second inverters 22 and 24 are not switched on or off, there are no switching losses in the first inverter 22 and the second inverter 24, thus improving power supply efficiency.

[0022] When the state of charge (SOC1) of the first battery 13 is higher than the state of charge (SOC2) of the second battery 14, the system ECU50 controls the first and second inverters 22 and 24 in a parallel charging power supply manner while using the power from the first battery 13 to charge the second battery 14. Figure 2 This diagram illustrates the current flow when the first battery 13 has a higher state of charge (SOC1) than the second battery 14, and they are connected in parallel for power supply. In the diagram, the thick solid lines and thick dashed lines with arrows represent the currents in the first and second batteries 13 and 14, respectively. Figure 2 As shown by the thick solid line with arrows, the first battery 13 is powered by the current flowing sequentially from the first battery 13 through the first positive line 31, the positive line of the charging power supply line 42, the charging power supply connector 44, the negative line of the charging power supply line 42, the parallel line 36 (the first parallel relay Rp1), and the first battery 13. Figure 2As shown by the thick dashed line with arrows, the second battery 14 is charged by the current flowing sequentially 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. At this time, the first and second inverters 22 and 24 can perform either buck control or boost control to make the current of the second battery 14 the charging current, or they can fix the upper arms of both the first inverter 22 and the second inverter 24 to be on (and the lower arms to be off). The second battery 14 is charged by the power from the first battery 13, thus the state of charge (SOC1) decreases and the state of charge (SOC2) increases. Therefore, the deviation between SOC1 and SOC2 can be suppressed.

[0023] When the state of charge (SOC1) of the first battery 13 is lower than the state of charge (SOC2) of the second battery 14, the system ECU 50 controls the first inverter 22 and the second inverter 24 to perform parallel charging and power supply while using power from the second battery 14 to charge the first battery 13. Figure 3 This diagram illustrates the current flow when the first battery 13 has a lower state of charge (SOC1) than the second battery 14, and they are connected in parallel for power supply. In the diagram, the thick solid lines and thick dashed lines with arrows represent the currents in the first and second batteries 13 and 14, respectively. Figure 2 As shown by the thick dashed line with arrows, the charging power supply connector 44 is powered by the current flowing sequentially 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 power supply line 42, the charging power supply connector 44, the negative line of the charging power supply line 42, and the second battery 14. Figure 3 As shown by the thick solid line with arrows, the first battery 13 is charged by the current flowing sequentially 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. At this time, the first inverter 22 and the second inverter 24 can perform either buck control or boost control to make the current of the second battery 14 the supply current and the charging current of the first battery 13, or the upper arms of both the first inverter 22 and the second inverter 24 can be fixed to be on (and the lower arms fixed to be off). The first battery 13 is charged by the power from the second battery 14, thus increasing the state of charge (SOC1) and decreasing the state of charge (SOC2). This suppresses the deviation between SOC1 and SOC2.

[0024] In the above embodiments, the operation of this disclosure when applied to parallel power supply has been described. However, the first and second inverters 22 and 24 can also be controlled in a way that reverses the flow of the current to apply this disclosure to the operation when applied to parallel charging.

[0025] The above describes the implementation methods for carrying out this disclosure, but this disclosure is not limited to such implementation methods, and can of course be implemented in various ways without departing from the spirit of this disclosure.

[0026] Industrial utilization potential

[0027] This disclosure can be applied to industries such as power supply system manufacturing.

Claims

1. A power supply system comprising a first battery and a second battery, wherein, The power system includes: a motor with three-phase coils; The first inverter is connected to the first battery via a first positive line and a negative line, and is also connected to one end of the three-phase coil. The second inverter is connected to the second battery via the second positive line and the negative line, and is also connected to the other end of the three-phase coil. A connector for charging and power supply, which is connected to the first positive wire and the negative wire, and can be electrically connected to a charging and power supply device; as well as The control device, when performing parallel charging power supply by using the power of the charging power supply equipment to charge the first battery and the second battery, or using the power of the first battery and the second battery to supply power to the charging power supply equipment, fixes the upper bridge arms of the first inverter and the second inverter to be connected when the state of charge of the first battery is equal to that of the second battery; when the state of charge of the first battery is higher than that of the second battery, performs the parallel charging power supply while charging the second battery using the power from the first battery; and when the state of charge of the first battery is lower than that of the second battery, performs the parallel charging power supply while charging the first battery using the power from the second battery.

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