Charging control device

Abstract

To provide a charging control device capable of appropriately charging two batteries simultaneously in parallel.SOLUTION: A charging control device is configured to charge a first battery connected to one end of a winding of an electric motor having a plurality of phases via a first inverter and a second battery connected to the other end of the winding via a second inverter from a charger via a first path that passes through the first inverter, the second inverter, and the winding and a second path that does not pass through the first inverter, the second inverter, and the winding, respectively and includes: a calculation unit for calculating SOCs of the first and second batteries; and a control unit for controlling currents flowing from the charger to the first and second batteries, respectively. The control unit limits a current flowing from the charger to the battery having a higher SOC by using an instruction value of an output current with respect to the charger and an instruction value of a current flowing from the charger to the first battery via the first path with respect to the first and second inverters so that a difference in SOC between the first and second batteries is reduced.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a charge control device. [Background technology]

[0002] Regarding battery charging control, for example, Patent Document 1 describes a power supply system in which an electric motor is driven by two sets of batteries and an inverter, and two batteries are charged simultaneously and in parallel from a charging stand. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-5394 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above power supply system, the charging path for one battery passes through the inverters and the electric motor, but the charging path for the other battery does not pass through the inverters and the electric motor, so the impedance of the charging path for one battery is greater than the impedance of the charging path for the other battery.

[0005] Therefore, even if there is no substantial difference in the open circuit voltage (OCV) characteristics of the two batteries, the difference in charging current between each battery will cause a difference in the SOC (State of Charge) of each battery, which will result in a shorter duration of power supply to, for example, an electric motor, compared to when the SOC of the two batteries is the same.

[0006] The present invention has been made in view of the above-mentioned problems, and has an object to provide a charge control device that can appropriately charge two batteries simultaneously in parallel. [Means for solving the problem]

[0007] The charging control device of the present invention charges a first battery connected to one end of a multi-phase winding of an electric motor via a first inverter and a second battery connected to the other end of the multi-phase winding via a second inverter from a charger via a first path that passes through the first inverter, the second inverter, and the multi-phase winding, and a second path that does not pass through the first inverter, the second inverter, and the multi-phase winding.The charging control device has a calculation unit that calculates the SOC of each of the first battery and the second battery, and a control unit that controls the current flowing from the charger to each of the first battery and the second battery, and the control unit limits the current flowing from the charger to the battery with a higher SOC, of ​​the first battery or the second battery, by an output current command value for the charger and an output current command value for the first inverter and the second inverter that flows from the charger to the first battery via the first path, so that the difference in SOC between the first battery and the second battery is reduced. [Effects of the Invention]

[0008] According to the present invention, two batteries can be appropriately charged simultaneously in parallel. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram showing an example of a vehicle system. [Figure 2] FIG. 2 is a flowchart illustrating an example of the charge control process. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Vehicle system configuration) 1 is a configuration diagram showing an example of a vehicle system S. The vehicle system S is mounted on a vehicle such as an electric vehicle or a hybrid vehicle. The vehicle system S includes a charge control device 1 and a drive circuit C. The drive circuit C includes storage batteries 20 and 30, voltage sensors 21 and 31, current sensors 22 and 32, capacitors 23 and 33, drivers 40 and 41, relays 50 to 54, inverters 6 and 7, an electric motor 8, and an inlet 90.

[0011] The electric motor 8 is, for example, a motor, and operates as a power source for driving the vehicle. The electric motor 8 has, for example, u-phase, v-phase, and w-phase windings 81 to 83.

[0012] Inverter 6 is an example of a first inverter, and inverter 7 is an example of a second inverter. Inverter 6 is connected to one end Ta of each of windings 81 to 83, and inverter 7 is connected to the other end Tb of each of windings 81 to 83. Inverter 6 includes switching elements 61 to 66, and inverter 7 includes switching elements 71 to 76. A free wheel diode D is connected in parallel to each of switching elements 61 to 66 and 71 to 76. Examples of switching elements 61 to 66 and 71 to 76 include, but are not limited to, IGBTs (Insulated Gate Bipolar Transistors).

[0013] In inverter 6, one input / output terminal of each of upper-arm switching elements 61-63 is connected to power supply line VDDa, and one input / output terminal of each of lower-arm switching elements 64-66 is connected to ground line SGa. The upper-arm switching elements 61-63 and the lower-arm switching elements 64-66 are connected in series at their other input / output terminals, and their contacts are connected to one end Ta of windings 81-83, respectively.

[0014] In inverter 7, one input / output terminal of each of upper-arm switching elements 71-73 is connected to power supply line VDDb, and one input / output terminal of each of lower-arm switching elements 74-76 is connected to ground line SGb. The upper-arm switching elements 71-73 and the lower-arm switching elements 74-76 are connected in series at their other input / output terminals, and their contacts are connected to the other ends Tb of windings 81-83, respectively.

[0015] The capacitor 23 is connected between the power supply line VDDa and the ground line SGa, and the capacitor 33 is connected between the power supply line VDDb and the ground line SGb.

[0016] Furthermore, relay 53, current sensor 22, storage battery 20, and relay 54 are directly connected in this order between power supply line VDDa and ground line SGa, and relay 50, current sensor 32, storage battery 30, and relay 52 are directly connected in this order between power supply line VDDb and ground line SGa. Furthermore, voltage sensor 21 is connected in parallel to storage battery 20, and voltage sensor 31 is connected in parallel to storage battery 30. Furthermore, relay 51 connects the contact between storage battery 20 and relay 54 and the contact between current sensor 32 and storage battery 30.

[0017] The storage battery 20 is an example of a first battery, and the storage battery 30 is an example of a second storage battery. The storage batteries 20 and 30 are, for example, lithium ion batteries. The electric motor 8 is driven by power supplied from at least one of the storage batteries 20 and 30. The storage batteries 20 and 30 are connected to one end Ta and the other end Tb of each of the windings 81 to 83 of the electric motor 8 via the inverters 6 and 7, respectively.

[0018] When relays 50 to 52 are in an open state and relays 53 and 54 are in a closed state, storage battery 20 supplies power to electric motor 8 via inverter 6. When relays 50 and 52 are in a closed state and relays 51, 53 and 54 are in an open state, storage battery 30 supplies power to electric motor 8 via inverter 7. When relays 51 to 53 are in a closed state and relays 50 and 54 are in an open state, storage batteries 20 and 30 are connected in series to each other and supply power to electric motor 8 via inverter 6.

[0019] Drivers 40 and 41 respectively use PWM (Pulse Width Modulation) signals to turn on and off switching elements 61 to 66 and 71 to 76 of inverters 6 and 7. As a result, inverters 6 and 7 convert the DC current output from storage batteries 20 and 30 into three-phase AC current when driving motor 8. At this time, capacitors 23 and 33 smooth the DC voltage.

[0020] Voltage sensors 21 and 31 detect the voltages across storage batteries 20 and 30, respectively, and output the detected voltages to charge control device 1. Current sensors 22 and 32 detect the currents flowing through storage batteries 20 and 30, respectively, and output the detected currents to charge control device 1.

[0021] While the motor 8 is stopped, the storage batteries 20 and 30 are simultaneously charged from a charging stand 9 connected to an inlet 90. The storage battery 20 is charged from the charging stand 9 via a charging path Ra, and the storage battery 30 is charged from the charging stand 9 via a charging path Rb. The charging path Ra passes through the inverter 7, the windings 81-83 of the motor 8, and the inverter 6, in that order, to reach the positive electrode of the storage battery 20. The charging path Rb passes through the inverter 7, the windings 81-83 of the motor 8, and the inverter 6, to reach the positive electrode of the storage battery 30. The charging path Ra is an example of a first path, and the charging path Rb is an example of a second path. In FIG. 1, the portion of the charging path Ra that passes through the v-phase and w-phase windings 82 and 83 is not shown.

[0022] During charging, inverters 6 and 7 operate as step-up converters or step-down converters. When operating as step-up converters, switching elements 71 to 73 are maintained in the on state, switching elements 74 to 76 are maintained in the off state, and switching elements 61 to 66 are controlled on and off by PWM signals. When operating as step-down converters, switching elements 61 to 63 are maintained in the on state, switching elements 64 to 66 are maintained in the off state, and switching elements 71 to 76 are controlled on and off by PWM signals. At this time, windings 81 to 83 function as inductors.

[0023] Therefore, the impedance of charging path Ra is greater than the impedance of charging path Rb. Therefore, if there is no substantial difference in the OCV characteristics of the two storage batteries 20, 30, the difference in charging current between each storage battery 20, 30 will also cause a difference in the SOC between each storage battery 20, 30. For this reason, for example, when the storage batteries 20, 30 are connected in series with each other, the duration of power supply to the electric motor 8 will be shorter than when the two storage batteries 20, 30 have the same SOC.

[0024] In response to this, the charge control device 1 charges the storage batteries 20, 30 simultaneously from the charging stand 9 so as to reduce the difference in SOC. The charging stand 9 is an example of a charger. The charge control device 1 is a computer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. For example, the charge control device 1 may be realized by one or more ECUs (Electronic Control Units). The charge control device 1 operates the CPU according to a program stored in the ROM.

[0025] The charge control device 1 has a calculation unit 10 and a control unit 11 as software functions formed by program operation. The calculation unit 10 and the control unit 11 may each be realized by hardware such as an integrated circuit. The charge control device 1 also has SOC map data 12 and Win map data 13 stored in advance in a nonvolatile memory such as an EEPROM (Electrically Erasable Programmable ROM).

[0026] The calculation unit 10 calculates the SOC of each of the storage batteries 20, 30. The calculation unit 10 acquires the detected values ​​of the current sensors 22, 32 and the voltage sensors 21, 31. The calculation unit 10 calculates an estimated OCV value for each of the storage batteries 20, 30, for example, from the detected voltage values. The correlation between OCV and SOC is registered in advance in the SOC map data 12. Note that the OCV characteristics of the storage batteries 20, 30 are substantially the same, so the same SOC map data 12 is used.

[0027] The calculation unit 10 calculates the SOC based on the estimated OCV value by referring to the SOC map data 12. However, the calculation unit 10 is not limited to this, and may calculate the SOC from the amount of time fluctuation in the integrated value of the current (charge capacity) of the storage batteries 20, 30.

[0028] The control unit 11 controls the currents Ia and Ib flowing from the charging stand 9 to the storage batteries 20 and 30 to the target values ​​Ita and Itb, respectively. Since the output current Is of the charging stand 9 is divided into the charging path Ra and the charging path Rb, the sum of the currents Ia and Ib (Ia + Ib) is equal to the output current Is of the charging stand 9.

[0029] The control unit 11 calculates target values ​​Ita and Itb from the Win of the storage batteries 20 and 30, respectively. Win is the allowable charging power amount, which is the upper limit of the power that the storage batteries 20 and 30 can accept. The control unit 11 calculates the Win of each storage battery 20 and 30, for example, by referring to Win map data 13 from the SOC of each storage battery 20 and 30. The Win map data 13 has a correlation between SOC and Win registered in advance. Note that if the storage batteries 20 and 30 are provided with temperature sensors, the control unit 11 may calculate Win from the SOC and temperature. Furthermore, the target values ​​Ita and Itb may be calculated from the viewpoint of protecting electrical components on the charging paths Ra and Rb, in addition to Win.

[0030] The control unit 11 calculates a target value Its of the output current Is of the charging stand 9 by summing the target values ​​Ita and Itb. The control unit 11 controls the charging stand 9 so that the output current Is becomes the target value Its. Here, the target value Its is an example of an instruction value of the output current for the charging stand 9.

[0031] Furthermore, the control unit 11 controls the inverters 6 and 7 via the drivers 40 and 41, respectively, so that the current Ia becomes equal to the target value Ita. Here, the target value Ita is an example of an instruction value for the inverters 6 and 7 of the current flowing from the charging stand 9 to the storage battery 20 via the charging path Ra. As a result, the current Ib is also controlled so as to become equal to the target value Itb.

[0032] At this time, the control unit 11 calculates the duty ratio of the PWM signal based on a predetermined calculation formula or map data from the target value Ita and outputs it to the drivers 40, 41. The drivers 40, 41 calculate the on / off timing of the switching elements 61-66, 71-76 according to the duty ratio to generate the PWM signal. The drivers 40, 41 are realized, for example, by integrated circuits.

[0033] Furthermore, control unit 11 corrects one of target values ​​Ita, Itb depending on the magnitude relationship between storage batteries 20, 30. Control unit 11 limits current Ia, Ib flowing through storage battery 20, 30 having the higher SOC by using an instruction value for output current Is to charging stand 9 and an instruction value for current flowing from charging stand 9 to storage battery 20 via charging path Ra to inverters 6, 7, so as to reduce the difference between the SOCs. Specifically, control unit 11 compares the SOC of storage battery 20 with that of storage battery 30, and reduces target values ​​Ita, Itb of storage battery 20, 30 having the higher SOC below the value based on Win, using target values ​​Its, Ita.

[0034] For example, when the SOC of storage battery 20 is higher than the SOC of storage battery 30, control unit 11 reduces target value Ita to suppress an increase in the SOC of storage battery 20. At this time, control unit 11 reduces target value Its of the output current of charging stand 9 by an amount equivalent to the reduction in target value Ita so that target value Itb of the current of the other storage battery 30 is maintained at a value based on Win.

[0035] On the other hand, when the SOC of the storage battery 30 is higher than the SOC of the storage battery 20, the control unit 11 reduces the target value Itb to suppress an increase in the SOC of the storage battery 30. At this time, the control unit 11 maintains the target value Ita of the current of the other storage battery 20 at a value based on Win, and reduces the target value Its of the output current of the charging stand 9 by the amount of the reduction in the target value Itb.

[0036] Furthermore, the control unit 11 determines the amount of reduction in the target value Ita or the target value Itb, for example, in accordance with the absolute value of the difference between the SOC of the storage battery 20 and the SOC of the storage battery 30. As a result, the currents Ia and Ib are controlled so that the difference in SOC between the storage batteries 20 and 30 is reduced.

[0037] In this way, the control unit 11 limits the current flowing through the storage battery 20, 30 with the higher SOC by the target values ​​Its and Ita so as to reduce the difference in SOC between the storage batteries 20, 30. Therefore, the storage batteries 20, 30 are appropriately charged simultaneously in parallel so that the SOCs of the storage batteries 20, 30 are substantially the same after charging is completed. This reduces the effect of the SOC on the duration of power supply to the electric motor 8.

[0038] (Charging control device operation) 2 is a flowchart showing an example of the charge control process. The charge control process is executed, for example, when the driving of the electric motor 8 stops and the charging stand 9 is connected to the inlet 90.

[0039] First, the control unit 11 instructs the charging stand 9 to output a predetermined value of current Is (step St1). Next, the calculation unit 10 acquires the detected values ​​from the voltage sensors 21 and 31 (step St2). Next, the calculation unit 10 calculates the SOC of the storage battery 20 (hereinafter referred to as SOCa) and the SOC of the storage battery 30 (hereinafter referred to as SOCb) from the detected values ​​based on the SOC map data 12 (step St3).

[0040] Next, the control unit 11 calculates Win (hereinafter, Win_a) of the storage battery 20 and Win (hereinafter, Win_b) of the storage battery 30 from the Win map data 13 based on SOCa and SOCb (step St4). Next, the control unit 11 calculates target values ​​Ita, Itb, and Its from Win_a and Win_b, respectively (step St5).

[0041] Next, the control unit 11 compares SOCa and SOCb with each other (step St6). When SOCa > SOCb holds (Yes in step St6), the control unit 11 decreases the target value Ita (step St7). On the other hand, when SOCa > SOCb does not hold (No in step St6), the control unit 11 determines whether SOCa < SOCb holds (step St8). When SOCa < SOCb holds (Yes in step St8), the control unit 11 decreases the target value Itb (step St9). Note that the control unit 11 also changes the target value Its in accordance with the decrease in the target values Ita and Itb.

[0042] <000015,3> The control unit 11 sets the amount of decrease in the target values Ita and Itb to, for example, a value obtained by multiplying |SOCa - SOCb| by a predetermined value. Also, when SOCa = SOCb holds (No in step St8), the target values Ita and Itb are not changed either.

[0043] Next, the control unit 11 controls the output current Is to the target value Its with respect to the charging stand 9 (step St10), and controls the current Ib flowing through the storage battery 20 to the target value Itb with respect to the inverters 6 and 7 (step St11). Thereby, the current Ia is also controlled to the target value Ita.

[0044] Next, the control unit 11 determines whether charging is completed (step St12). Whether charging is completed may be determined, for example, by whether either SOCa or SOCb has reached a predetermined value. When charging is not completed (No in step St12), each process after step St2 is re-executed. When charging is completed (Yes in step St12), this process ends. In this way, the charging control process is performed.

Explanation of Signs

[0045] <00001,64>1 Charging control device, 6, 7 Inverters (first and second inverters), 8 Motor, 9 Charging stand (charger), 10 Calculation unit, 11 Control unit, 20, 30 Storage batteries (batteries), 81 - 83 Windings, Ra, Rb Charging paths (first and second paths), Its, Ita, Itb Target values (indicated values)

Claims

[Claim 1] A charge control device charges a first battery connected to one end of a multi-phase winding of an electric motor via a first inverter and a second battery connected to the other end of the multi-phase winding via a second inverter from a charger via a first path that passes through the first inverter, the second inverter, and the multi-phase winding, and a second path that does not pass through the first inverter, the second inverter, and the multi-phase winding, a calculation unit that calculates an SOC of each of the first battery and the second battery; a control unit that controls the current flowing from the charger to each of the first battery and the second battery, the control unit limits the current flowing from the charger to one of the first battery and the second battery, which has a higher SOC, by an instruction value of an output current for the charger and instruction values ​​for the first inverter and the second inverter of a current flowing from the charger to the first battery via the first path, so that the difference in SOC between the first battery and the second battery is reduced. Charging control device.

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