vehicle

Abstract

The present invention relates to a vehicle. The vehicle includes: a motor configured to generate electricity; a power storage device configured to store electricity generated by the motor; a drive device electrically connected to the power storage device and the motor to drive the motor; and a processor configured to control the drive device so that, when a circulating current that does not flow to the drive device but circulates within the power storage device or between the inside and outside of the power storage device is generated, the amount of power generated by the motor is reduced compared to a case where no circulating current is generated.

Description

Technical Field

[0001] The present disclosure relates to a vehicle, and more particularly to a vehicle including a power storage device. Background Art

[0002] Japanese Patent Application Laid-Open No. 2019-119397 discloses a power supply system for boosting the power supplied from a battery in a vehicle and supplying it to a motor. This power supply system identifies the location of an abnormality in a converter, inverter, motor, or other component. In this power supply system, when the abnormality occurs in a boosted location, the boosted voltage is set lower than when the abnormality occurs in a pre-boosted location. Summary of the Invention

[0003] In vehicles, due to a malfunction in the power storage device, the current from the power storage device may circulate within the power storage device or between the internal and external parts of the power storage device rather than flowing to the motor drive unit. This current (hereinafter referred to as "circulating current") can cause power loss. Japanese Patent Application Laid-Open No. 2019-119397 does not address this issue.

[0004] The present disclosure has been made to solve the above-mentioned problems, and an object thereof is to provide a vehicle capable of reducing power loss due to circulating current in a power storage device.

[0005] A vehicle according to a technical solution of the present disclosure comprises: a motor configured to generate electricity; a power storage device configured to store electricity generated by the motor; a drive device electrically connected to the power storage device and the motor to drive the motor; and a processor configured to control the drive device so that, when a circulating current is generated that does not flow to the drive device but circulates inside the power storage device or between the inside and outside of the power storage device, the amount of power generated by the motor is suppressed compared to a case where no circulating current is generated.

[0006] By adopting this configuration, the amount of power charged to the power storage device decreases, reducing the amount of power stored in the power storage device and lowering the voltage of the power storage device. Consequently, the circulating current in the power storage device decreases, thereby reducing power loss caused by the circulating current in the power storage device.

[0007] In the above aspect, the drive device may include an inverter. The processor may be configured to control the inverter so that when a circulating current is generated, the regenerative torque of the motor is reduced compared to when no circulating current is generated.

[0008] By adopting this configuration, the power generated by the motor during regenerative braking of the vehicle decreases, thereby reducing the amount of power charged to the power storage device. Consequently, the amount of electricity stored in the power storage device decreases, lowering the voltage of the power storage device. This also reduces the circulating current in the power storage device. Consequently, power loss caused by the circulating current in the power storage device can be reduced.

[0009] In the above aspect, the vehicle may further include a load connected to the power line between the power storage device and the drive device. The processor may be configured to control the load so that when a circulating current is generated, power consumption of the load is increased compared to when no circulating current is generated.

[0010] By adopting this configuration, the power supplied from the power storage device to the load increases, causing the power storage device's stored capacity to decrease more rapidly than when this control is not implemented. Consequently, the power storage device's voltage decreases more rapidly than in this case. Consequently, the circulating current in the power storage device decreases more rapidly than in this case. This reduces the total amount of power loss caused by the circulating current in the power storage device.

[0011] In the above embodiment, the vehicle may further include a power converter connected to the power line between the power storage device and the drive device. The power converter may be configured to receive power stored in the power storage device via the power line and convert the power. The processor may be configured to control the power converter so that when a circulating current is generated, the output power of the power converter is increased compared to when no circulating current is generated.

[0012] By adopting this configuration, the power supplied from the power storage device or motor to the power converter increases, causing the power storage device's stored capacity to decrease more rapidly than when this control is not implemented. Consequently, the power storage device's voltage decreases more rapidly than in this case. Consequently, the circulating current in the power storage device decreases more rapidly than in this case. This reduces the total amount of power loss caused by the circulating current in the power storage device.

[0013] According to the present disclosure, it is possible to provide a vehicle capable of reducing power loss due to circulating current in a power storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals designate like elements, and in which:

[0015] Figure 1 This is a diagram showing the overall structure of a vehicle according to the first embodiment.

[0016] Figure 2 It is a diagram schematically showing how circulating current flows inside a battery.

[0017] Figure 3 This is a flowchart showing an example of a procedure of a process executed by the control device according to the first embodiment.

[0018] Figure 4 This is a diagram for explaining a method of controlling the inverter when suppressing the amount of power generated by the motor generator.

[0019] Figure 5 This is a diagram showing an example of temporal changes in the internal resistance value of a battery cell, the battery voltage, and the current value of the circulating current when the motor generator generates power.

[0020] Figure 6 This is a diagram schematically showing how circulating current flows outside the battery.

[0021] Figure 7 It is a diagram showing the overall structure of a vehicle according to the second embodiment.

[0022] Figure 8 This is a flowchart showing an example of a procedure of a process executed by the control device according to the second embodiment.

[0023] Figure 9 This is a diagram showing an example of temporal changes in insulation resistance, battery voltage, and circulating current value when the motor generator generates power. DETAILED DESCRIPTION

[0024] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. It should be noted that the same or corresponding parts in the drawings are denoted by the same reference numerals, and their description will not be repeated.

[0025] [Implementation Method 1]

[0026] Figure 1 This figure shows the overall structure of a vehicle according to Embodiment 1. Vehicle 100 is an electric vehicle that travels using electricity. While this embodiment illustrates an example where vehicle 100 is an electric vehicle, vehicle 100 may also be a hybrid vehicle or plug-in hybrid vehicle that also includes an engine (not shown), or a fuel cell vehicle that also includes a fuel cell (not shown), or other electric vehicle.

[0027] Reference Figure 1 Vehicle 100 includes a battery B1, a system relay SR, a voltage sensor 10, a current sensor 17, power lines PL and NL, a PCU (Power Control Unit) 18, a motor generator MG, and a control device 30. Furthermore, vehicle 100 includes a DC / DC converter 13, an air conditioner 14, an auxiliary device 19, and a battery B2.

[0028] Battery B1 is a battery pack including a plurality of battery cells. Each battery cell is a secondary battery such as a lithium-ion battery, a lead-acid battery, or a nickel-metal hydride battery. A lithium-ion battery is a secondary battery that uses lithium as a charge carrier. In addition to general lithium-ion batteries with liquid electrolytes, it also includes all-solid-state batteries using solid electrolytes. Battery B1 is shown as an example of a storage device configured for charging and discharging. Instead of battery B1, a storage device composed of storage elements such as double-layer capacitors can also be used. Battery B1 is connected to PCU18 (described later) via a system relay SR.

[0029] Voltage sensor 10 detects voltage VCE(k) of each battery cell of battery B1. Specifically, voltage VCE(k) is the voltage of the kth battery cell among the n battery cells included in battery B1 (n and k are natural numbers, 1≤k≤n). The detection value of voltage sensor 10 is output to control device 30.

[0030] Current sensor 17 detects current Ib output from battery B1 . The detection value of current sensor 17 is output to control device 30 .

[0031] Power line PL electrically connects the positive electrode of battery B1 to PCU 18 , while power line NL electrically connects the negative electrode of battery B1 to PCU 18 .

[0032] PCU 18 is a drive unit that drives motor generator MG (described later). PCU 18 includes capacitor 12, voltage sensor 16, and inverter 20. Capacitor 12 is connected between power line PL and power line NL. Voltage sensor 16 detects voltage VH across the terminals of capacitor 12. The value detected by voltage sensor 16 is output to control device 30.

[0033] Inverter 20 is configured to convert DC power received from power lines PL and NL into AC power. Inverter 20 then uses the converted AC power to drive motor generator MG. Furthermore, inverter 20 is also configured to convert AC power generated by motor generator MG (described later) into DC power during braking of vehicle 100.

[0034] Inverter 20 includes a U-phase arm 21, a V-phase arm 22, and a W-phase arm 23. U-phase arm 21 includes switching elements Q1 and Q2, and diodes D1 and D2 connected in antiparallel to switching elements Q1 and Q2, respectively. V-phase arm 22 includes switching elements Q3 and Q4, and diodes D3 and D4 connected in antiparallel to switching elements Q3 and Q4, respectively. W-phase arm 23 includes switching elements Q5 and Q6, and diodes D5 and D6 connected in antiparallel to switching elements Q5 and Q6, respectively.

[0035] Switching elements Q1 to Q6 are, for example, IGBTs (Insulated Gate Bipolar Transistors) or MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). Switching elements Q1 to Q6 are controlled using PWM (Pulse Width Modulation) based on a switching cycle and duty cycle according to a control signal PWMS output from control device 30.

[0036] Motor generator MG is an AC rotating electric machine, for example, a three-phase AC synchronous motor generator. Motor generator MG is electrically connected to inverter 20. Motor generator MG rotates using electric power supplied from battery B1 via inverter 20, thereby driving wheels (not shown) of vehicle 100. This causes vehicle 100 to travel.

[0037] Furthermore, motor generator MG is configured to generate electricity during braking of vehicle 100. The AC power generated by motor generator MG is converted into DC power by inverter 20. The converted DC power is stored in battery B1 via power lines PL and NL. Furthermore, this DC power can be supplied to battery B2, auxiliary equipment 19, or air conditioner 14 via DC / DC converter 13 (all described below).

[0038] Vehicle 100 further includes a charging device (not shown) configured to convert AC power supplied from an external power supply (not shown) into charging power (DC power) for battery B1 when vehicle 100 is connected to the external power supply.

[0039] DC / DC converter 13 and air conditioner 14 are connected to power lines PL and NL. DC / DC converter 13 and air conditioner 14 are configured to operate by receiving DC power output from battery B1 or DC power output from inverter 20 during regenerative braking of vehicle 100 (when motor generator MG is generating electricity) via power lines PL and NL.

[0040] An air conditioner 14 is shown as an example of a load that operates in accordance with a control signal CTA1 from the control device 30 .

[0041] DC / DC converter 13 is configured to convert received power into DC power at an auxiliary machine voltage level (e.g., 12 V). DC / DC converter 13 is connected to battery B2 and auxiliary machine 19 and operates in accordance with control signal CTA2 from control device 30. DC / DC converter 13 is configured, for example, by an insulating transformer.

[0042] Battery B2, like Battery B1, is shown as an example of a power storage device configured to perform charge and discharge. Battery B2 is a power storage device for auxiliary machinery that stores DC power converted by DC / DC converter 13. Battery B2 is a battery pack consisting of multiple battery cells, each of which is a secondary battery such as a lead-acid battery or a nickel-metal hydride battery. The auxiliary machinery 19 operates on DC power converted by DC / DC converter 13, such as the power stored in Battery B2.

[0043] The control device 30 is configured to include a CPU (Central Processing Unit) and memory (neither of which is shown). The CPU controls various devices in the vehicle 100 based on information stored in the memory. The memory includes ROM (Read Only Memory) and RAM (Random Access Memory). ROM stores programs executed by the CPU. RAM temporarily stores data referenced by the CPU. Control of the control device 30 is implemented through software processing, but can also be implemented through hardware manufactured within the control device 30.

[0044] Control device 30 controls various components of vehicle 100, including system relay SR, inverter 20, DC / DC converter 13, air conditioner 14, and auxiliary equipment 19. For example, control device 30 performs PWM control on inverter 20 so that motor generator MG outputs torque in accordance with torque command value TR when vehicle 100 is traveling or braking. Control device 30 can also adjust the SOC (State of Charge) of battery B2 by controlling DC / DC converter 13.

[0045] In vehicle 100 , due to a failure of a battery cell of battery B1 , the current of battery B1 may circulate inside battery B1 and not flow into inverter 20 .

[0046] Figure 2 Schematically shows how the circulating current flows inside the battery B1. Figure 2 In order to simplify the explanation, we select Figure 1 A portion of the components of the vehicle 100 is shown.

[0047] exist Figure 2 In the example, circulating current CC1 circulates in a circuit (hereinafter also referred to as a "circulating current circuit") formed by a portion of battery cells CELL(1) to CELL(k) among a plurality of battery cells CELL(1) to CELL(n) included in battery B1. Circulating current CC1 causes power loss.

[0048] Therefore, this embodiment describes a measure for reducing such power loss. Specifically, control device 30 controls inverter 20 so that, when circulating current CC1 is generated, the amount of power generated by motor generator MG is suppressed compared to when circulating current CC1 is not generated. More specifically, control device 30 controls inverter 20 so that, when circulating current CC1 is generated, the regenerative torque of motor generator MG is reduced compared to when circulating current CC1 is not generated.

[0049] The following describes a method for detecting circulating current CC1. Generally speaking, when circulating current CC1 is generated within battery B1, the internal resistance of the battery cells CELL(1) to CELL(k) through which circulating current CC1 flows is greater than the internal resistance of CELL(1) to CELL(k) when circulating current CC1 is not generated.

[0050] Therefore, the control device 30 can determine the generation of the circulating current CC1 based on the internal resistance of the battery cells CELL(1) to CELL(n) of the battery B1. Specifically, the control device 30 can determine the generation of the circulating current CC1 when the internal resistance of any of the battery cells CELL(1) to CELL(n) increases excessively.

[0051] It should be noted that control device 30 can calculate the internal resistance of each battery cell of battery B1 based on, for example, the voltage VCE(k) of each battery cell of battery B1 detected by voltage sensor 10 and the current Ib of battery B1 detected by current sensor 17. Specifically, control device 30 can plot the voltage value and current value of each battery cell of battery B1 on a voltage-current coordinate system and calculate the internal resistance of the battery cell from the slope of the straight line represented by the coordinates of each plotted point.

[0052] Then, the control device 30 determines whether at least one of the internal resistances of the battery cells is equal to or greater than a first threshold value, and determines the occurrence of the circulating current CC1 based on the determination that the internal resistance is equal to or greater than the first threshold value. The first threshold value is appropriately predetermined in a previous evaluation test or the like.

[0053] Figure 3 This is a flowchart showing an example of a procedure of a process executed by the control device 30 according to Embodiment 1. This flowchart is executed at predetermined time intervals.

[0054] Reference Figure 3 Controller 30 obtains detection values ​​of current Ib and voltage VCE(k) from current sensor 17 and voltage sensor 10, respectively (step S10), and calculates the internal resistance of each cell of battery B1 based on these detection values ​​(step S20).

[0055] Next, control device 30 determines whether the internal resistance of at least one battery cell in battery B1 is greater than or equal to a first threshold value (step S30). If the internal resistance of all battery cells in battery B1 is less than the first threshold value ("No" in step S30), control device 30 temporarily terminates processing and then returns to step S10 after the predetermined time interval. On the other hand, if the internal resistance of at least one battery cell in battery B1 is greater than or equal to the first threshold value ("Yes" in step S30), control device 30 determines that circulating current CC1 is occurring (step S40).

[0056] Next, the control device 30 controls the inverter 20 so that the amount of power generated by the motor generator MG is reduced compared to when the circulating current CC1 is not generated (step S50). Specifically, the control device 30 controls the inverter 20 so that when the circulating current CC1 is generated, the regenerative torque of the motor generator MG is reduced compared to when the circulating current CC1 is not generated. For example, the control device 30 controls the inverter 20 so that the power generated by this torque is zero or the power generated by this torque is used only for the air conditioner 14 and the auxiliary equipment 19.

[0057] As a result, the amount of power generated by motor generator MG is suppressed, reducing the amount of power supplied from motor generator MG to battery B1. Consequently, the SOC of battery B1 decreases. Battery B1's SOC is correlated with battery B1's voltage VH, so as battery B1's SOC decreases, battery B1's voltage VH decreases. Thus, as motor generator MG's power generation is suppressed, battery B1's voltage VH decreases.

[0058] Here, the current value of circulating current CC1 is based on the internal resistance of the circulating current circuit and the sum of the voltages of the battery cells CELL(1) to CELL(k) through which circulating current CC1 flows. Here, the sum of the voltages of battery cells CELL(1) to CELL(k) is related to the voltage VH of battery B1. Therefore, if the voltage VH of battery B1 decreases due to the reduction in the amount of power generated by motor generator MG, the sum of the voltages of battery cells CELL(1) to CELL(k) also decreases. Consequently, circulating current CC1 decreases. As a result, the power loss caused by circulating current CC1 can be reduced.

[0059] After the amount of power generation of motor generator MG is suppressed (after step S50 ), control device 30 temporarily ends the process and then returns the process to step S10 after the predetermined time interval.

[0060] Figure 4 This is a diagram for explaining a method of controlling the inverter 20 when suppressing the amount of power generated by the motor generator MG.

[0061] Control device 30 is configured to set a target voltage VHT for voltage VH in order to control voltage VH. Specifically, as described below, control device 30 performs feedback control based on the difference between the detected value of voltage VH and target voltage VHT. In this embodiment, PI (Proportional-Integral) control is employed as an example of feedback control.

[0062] Reference Figure 4 The control device 30 includes a subtraction unit 505 , a proportional term calculation unit 510 , an integral term calculation unit 515 , an addition unit 520 , an addition unit 530 , and an upper and lower limit processing unit 525 .

[0063] Subtraction unit 505 calculates deviation ΔVH (=VHT−VH) by subtracting voltage VH detected by voltage sensor 16 from target voltage VHT.

[0064] Proportional term calculation unit 510 calculates a proportional term in PI control by multiplying deviation ΔVH by a proportional coefficient.

[0065] Integral term calculation unit 515 multiplies deviation ΔVH by a predetermined gain and integrates the term obtained by the multiplication, thereby calculating the integral term in PI control.

[0066] The adding unit 520 calculates the sum of the proportional term and the integral term calculated by the proportional term calculating unit 510 and the integral term calculating unit 515 , respectively, as the controlled variable U1 .

[0067] Upper and lower limit processing unit 525 applies upper and lower limit processing to the control variable U1. This results in the control variable U2 being outputted as less than a predetermined upper limit and greater than a predetermined lower limit. It should be noted that this upper limit is appropriately predetermined, for example, so that the duty cycle of the PWM control of inverter 20 is neither too high nor too low. Adding unit 530 then outputs the control variable U3 after applying interference to the control variable U2.

[0068] Inverter 20 is controlled by control device 30 based on control variable U3. As a result, the torque of motor generator MG is adjusted, and voltage VH is adjusted to target voltage VHT.

[0069] In such a feedback control system, the control device 30 determines that the circulating current CC1 ( Figure 2 ), the target voltage VHT is lowered. Hereinafter, the target voltage VHT before the reduction is referred to as VHT1, and the target voltage VHT after the reduction is referred to as VHT2 (VHT1>VHT2).

[0070] Before target voltage VHT decreases from VHT1 to VHT2, control device 30 performs the feedback control described above so that voltage VH becomes VHT1. When target voltage VHT decreases from VHT1 to VHT2, control device 30 performs the feedback control described above so that voltage VH becomes VHT2.

[0071] Specifically, when voltage VH exceeds target voltage VHT (= VH2) in this case, control device 30 controls inverter 20 to suppress the amount of power generated by motor generator MG. This reduces the power supplied from motor generator MG to battery B1, lowering the SOC of battery B1. Consequently, voltage VH of battery B1 decreases, approaching VHT2.

[0072] In this way, the control device 30 controls the inverter 20 based on the detected value of the voltage VH and the target voltage VHT. As a result, when the circulating current CC1 is generated, the voltage VH eventually decreases from VHT1 to VHT2. In addition, due to the decrease in voltage VH, the battery cells CELL(1) to CELL(k) ( Figure 2 ) is reduced, thereby reducing the circulating current CC1. Therefore, the power loss caused by the circulating current CC1 can be reduced.

[0073] Figure 5 1 is a diagram showing an example of temporal changes in internal resistance value Rb, voltage VH, and current value IJ of circulating current CC1 of a certain battery cell of battery B1 when motor generator MG generates electric power. Figure 5 The horizontal axis represents the time t. Figure 5 In the upper, middle, and lower sections, the vertical axes represent the internal resistance value Rb, the voltage VH, and the current value IJ, respectively.

[0074] Specifically, line 605 shows the change of internal resistance Rb over time, line 610 shows the change of voltage VH over time, and line 615 shows the change of current IJ over time.

[0075] At time t1, internal resistance Rb, voltage VH, and current IJ are Rb1, VH1, and IJ1, respectively. At time t1, internal resistance Rb is Rb1, which is less than first threshold TH1 (line 605), so control device 30 determines that no circulating current CC1 is generated in battery B1.

[0076] At time t2, when the internal resistance value Rb rises to Rb2 which is equal to or higher than the first threshold value TH1 (line 605), the control device 30 determines that the circulating current CC1 is generated. Therefore, the control device 30 reduces the target voltage VHT from VHT1 to VHT2.

[0077] Next, during the period from time t2 to time t3 , control device 30 controls inverter 20 so as to suppress the amount of power generated by motor generator MG compared to the case where circulating current CC1 is not generated (before time t2 ).

[0078] Specifically, the control device 30 performs a reference Figure 4 The feedback control described above. As a result, the power supplied from the motor generator MG to the battery B1 decreases, and the SOC of the battery B1 decreases, so the voltage VH of the battery B1 decreases (line 610). Therefore, since the sum of the voltages of the battery cells CELL(1) to CELL(k) ( Figure 2 ) decreases, so the current value IJ of the circulating current CC1 decreases from IJ2 to IJ3 (line 615). As a result, the power loss caused by the circulating current CC1 is reduced.

[0079] As described above, in the first embodiment, control device 30 determines whether circulating current CC1 is occurring within battery B1 based on whether internal resistance value Rb is equal to or greater than first threshold value TH1. Furthermore, control device 30 controls inverter 20 so that, when circulating current CC1 is occurring, the amount of power generated by motor generator MG is suppressed compared to when circulating current CC1 is not occurring.

[0080] As a result, voltage VH decreases due to a decrease in the SOC of battery B1 , and thus circulating current CC1 decreases. Consequently, power loss due to circulating current CC1 decreases.

[0081] [Implementation Method 2]

[0082] While the first embodiment describes a case where circulating current CC1 is generated inside battery B1, the second embodiment describes a case where circulating current is generated between the inside and outside of battery B1 (ie, where circulating current flows outside battery B1).

[0083] Figure 6 Schematically shows the state in which the circulating current flows out of the battery B1. Figure 6 In the example shown in FIG. 1 , circulating current CC2 circulates between the interior of battery B1 and reference potential point GND (eg, vehicle body) of vehicle 100 . Insulation resistance RIS is the insulation resistance between battery B1 and reference potential point GND of vehicle 100 .

[0084] Figure 7 1 is a diagram showing the overall structure of a vehicle 100 according to a second embodiment. The vehicle 100 according to the second embodiment is different from the vehicle 100 according to the first embodiment in that it further includes an insulation resistance reduction detector 70. Figure 1) is different. In addition, in vehicle 100 of the second embodiment, the insulation resistance RIS is taken into consideration, which is different from vehicle 100 of the first embodiment. The rest of the structure of vehicle 100 of the second embodiment is basically the same as that of vehicle 100 of the first embodiment.

[0085] The insulation resistance reduction detector 70 is electrically connected to the negative electrode of the battery B1 and includes a coupling capacitor 15 , a resistor 50 , an oscillation circuit 40 , and a peak detection circuit 60 .

[0086] Coupling capacitor 15 is connected between the negative electrode of battery B1 and node N1. Coupling capacitor 15 is provided to insulate resistor 50, oscillation circuit 40, and peak detection circuit 60 from the negative electrode of battery B1. Resistor 50 is provided between node N1 and oscillation circuit 40.

[0087] The oscillation circuit 40 outputs an AC signal, which is output to the node N1 via the resistor 50 .

[0088] Peak detection circuit 60 detects the peak value of the voltage at node N1. The voltage at node N1 corresponds to the voltage of the AC signal output from oscillation circuit 40 divided by resistor 50 and insulation resistance RIS. Peak detection circuit 60 outputs signal SABN indicating the detected peak value to control device 30.

[0089] If the insulation resistance RIS decreases, a circulating current CC2 ( Figure 6 ). Furthermore, as the insulation resistance RIS decreases, the voltage across the insulation resistance RIS decreases. Therefore, the voltage at the node N1 connected to the insulation resistance RIS decreases as the insulation resistance RIS decreases. Consequently, as the insulation resistance RIS decreases, the peak value detected by the peak detection circuit 60 also decreases.

[0090] Therefore, control device 30 in the second embodiment determines whether insulation resistance RIS has excessively decreased based on the detected value of the peak value, and determines the occurrence of circulating current CC2 based on the determination that insulation resistance RIS has excessively decreased.

[0091] Specifically, if the peak value is less than the second threshold, control device 30 determines that insulation resistance RIS has excessively decreased. In this case, excessive current is likely to flow between battery B1 and reference potential point GND, and control device 30 determines that circulating current CC2 has occurred. The second threshold is appropriately determined in advance through prior evaluation tests, etc.

[0092] Figure 8 This is a flowchart showing an example of a procedure of a process executed by the control device 30 according to Embodiment 2. This flowchart is executed at predetermined time intervals.

[0093] Reference Figure 8 , the control device 30 obtains the detection value of the peak detection circuit 60 through the signal SABN (step S120).

[0094] Next, control device 30 determines whether the peak value is less than a second threshold value (step S130). If the peak value is greater than the second threshold value ("No" in step S130), control device 30 temporarily terminates processing and then returns to step S120 every time the predetermined time interval elapses. On the other hand, if the peak value is less than the second threshold value ("Yes" in step S130), control device 30 determines that circulating current CC2 is occurring (step S140).

[0095] Next, the control device 30 controls the inverter 20 so that the power generation amount of the motor generator MG is suppressed compared to the case where the circulating current CC2 is not generated (step S150). This power generation suppression method is the same as that in step S50 ( Figure 3 ) is the same as the method for suppressing the power generation amount implemented in the processing.

[0096] Figure 9 It represents the insulation resistance RIS, voltage VH and circulating current CC2 ( Figure 6 ) is a diagram showing an example of a change in the current value IJ' with time. Figure 9 The horizontal axis represents the time t. Figure 9 In the upper, middle and lower sections, the vertical axes represent the insulation resistance RIS, the voltage VH and the current value IJ', respectively.

[0097] Specifically, line 1015 shows the change of insulation resistance RIS over time, line 1010 shows the change of voltage VH over time, and line 1005 shows the change of current value IJ' over time.

[0098] At time t10, the insulation resistance RIS, voltage VH, and current value IJ' are RIS10, VH10, and IJ10, respectively. At time t10, the insulation resistance RIS is RIS10, which is greater than the second threshold value TH2 (line 1015), so the control device 30 determines that no external (at the time of the battery B1) has occurred. Figure 6 In the example, the circulating current CC2 of the reference potential point GND of the vehicle 100.

[0099] At time t11, when insulation resistance RIS decreases to RIS11, which is less than second threshold value TH2 (line 1015), control device 30 determines that circulating current CC2 is occurring. At time t11, current value IJ' of circulating current CC2 rapidly increases from IJ10 to IJ11 (line 1005). Therefore, based on this determination of circulating current CC2, control device 30 lowers target voltage VHT from VHT1 to VHT2.

[0100] Next, during the period from time t11 to time t12, the control device 30 controls the inverter 20 so as to suppress the amount of power generated by the motor generator MG compared to the case where the circulating current CC2 is not generated (before time t11). Specifically, the control device 30 executes reference Figure 4 As a result, the electric power supplied from motor generator MG to battery B1 decreases.

[0101] Furthermore, the SOC of the battery B1 decreases as the power decreases, so the voltage VH of the battery B1 decreases (line 1010). As a result, the battery cells CELL(1) to CELL(k) of the circulating current circuit ( Figure 6 ) decreases, so the circulating current CC2 decreases. Specifically, the current value IJ' of the circulating current CC2 decreases from IJ11 to IJ12 (line 1005). As a result, the power loss caused by the circulating current CC2 is reduced.

[0102] As described above, in the second embodiment, control device 30 determines whether circulating current CC2 is flowing out of battery B1 based on whether insulation resistance RIS is less than second threshold value TH2. Furthermore, control device 30 controls inverter 20 so that, when circulating current CC2 is generated, the amount of power generated by motor generator MG is suppressed compared to when circulating current CC2 is not generated. As a result, power loss due to circulating current CC2 is reduced.

[0103] [Implementation Method 3]

[0104] In generating circulating current ( Figure 2 、 Figure 6 ), the vehicle 100 of the third embodiment controls the inverter 20 in a manner that suppresses the amount of power generated by the motor generator MG and further controls the air conditioner 14, the auxiliary device 19, and the DC / DC converter 13 as follows ( Figure 1 、 Figure 7 ). As a result, the circulating current is reduced more quickly than in the cases of the first and second embodiments. Figure 1 or Figure 7 .

[0105] As an example, the control device 30 further controls the air conditioner 14 or the auxiliary device 19 and the DC / DC converter 13 so that when a circulating current is generated, the power consumption in the air conditioner 14 or the auxiliary device 19 is temporarily reduced (for example, the voltage VH is reduced to VHT2 ( Figure 4 ) during the period) becomes larger.

[0106] As a result, at least a portion of the electric power generated by motor generator MG, which would otherwise be supplied to battery B1 in the first and second embodiments, is supplied to air conditioner 14 or auxiliary device 19 instead of battery B1. Alternatively, the amount of electric power stored in battery B1 supplied to air conditioner 14 or auxiliary device 19 is temporarily increased compared to the first and second embodiments. Consequently, the SOC of battery B1 decreases more rapidly than in the first and second embodiments.

[0107] As a result, when a circulating current is generated, the voltage VH is equal to the voltage VH which ... Figure 4 、 Figure 5 as well as Figure 8 The voltage is reduced to the target voltage VHT (= VHT2) faster than the case of the feedback control described above. Figure 4 As a result, the total amount of power loss during the period from when voltage VH drops to when voltage VHT2 is reduced can be reduced.

[0108] [Variation of Embodiment 3]

[0109] In generating circulating current ( Figure 2 、 Figure 6 ), the control device 30 may control the DC / DC converter 13 in addition to controlling the inverter 20 in a manner to suppress the power generation of the motor generator MG so as to increase the SOC of the battery B2 compared to the case where no circulating current is generated.

[0110] Specifically, control device 30 temporarily (for example, until voltage VH reaches VHT2 ) controls DC / DC converter 13 so that at least a portion of the electric power stored in battery B1 is stored in battery B2 .

[0111] This temporarily increases the power consumption of battery B1, causing the SOC of battery B1 to decrease more rapidly than when this control is not executed. Consequently, voltage VH, which is correlated with the SOC of battery B1, also decreases more rapidly than in the aforementioned case. As a result, the total amount of power loss during the period from when voltage VH reaches VHT2 can be reduced.

[0112] Furthermore, the power stored in battery B1 can be stored in battery B2 for storing power required for operating other equipment (eg, auxiliary machine 19). Therefore, this modification can also be applied when auxiliary machine 19 is not operating when circulating current is generated.

[0113] Alternatively, control device 30 may further temporarily (for example, until voltage VH reaches VHT2 ) control DC / DC converter 13 so that at least a portion of the electric power generated by motor generator MG is supplied to battery B2 instead of battery B1 .

[0114] This control reduces the SOC of battery B1 more quickly than when this control is not performed. Consequently, voltage VH, which is correlated with the SOC of battery B1, also decreases more quickly than in the aforementioned case. As a result, the total amount of power loss during the period from when voltage VH reaches VHT2 can be reduced.

[0115] As described above, the control device 30 can also control the DC / DC converter 13 so that when a circulating current is generated, the output power of the DC / DC converter 13 (for example, equivalent to the power consumption of the auxiliary machine 19 and the power stored in the battery B2) becomes larger than when no circulating current is generated.

[0116] [Other modifications]

[0117] exist Figure 1 or Figure 7 In the embodiment, a converter may be provided between the battery B1 and the inverter 20 as a component of the PCU 20 .

[0118] The embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A vehicle, characterized in that: include: a motor configured to generate electricity; a power storage device configured to store the electric power generated by the motor; a driving device electrically connected to the power storage device and the motor, for driving the motor; an insulation resistance reduction detector that detects a reduction in insulation resistance between the interior of the power storage device and a body of the vehicle; and The processor is configured to, when a decrease in the insulation resistance is detected by the insulation resistance decrease detector, determine that a circulating current that does not flow to the drive device but circulates between the interior of the power storage device and the vehicle body has been generated, and when it is determined that the circulating current has been generated, suppress the power generation of the motor compared to a case where the circulating current is not generated.

2. The vehicle according to claim 1, characterized in that The driving device includes an inverter, The processor is configured to control the inverter so that, when the circulating current is generated, the regenerative torque of the motor becomes smaller than when the circulating current is not generated.

3. The vehicle according to claim 1 or 2, characterized in that The vehicle further includes a load connected to a power line between the power storage device and the drive device, wherein The processor controls the load so that, when the circulating current is generated, power consumption of the load increases compared to a case where the circulating current is not generated.

4. The vehicle according to claim 1 or 2, characterized in that The vehicle further includes a power converter connected to a power line between the power storage device and the drive device, wherein: The power converter is configured to receive the electric power stored in the power storage device via the power line and convert the electric power. The processor is configured to control the power converter so that, when the circulating current is generated, the output power of the power converter becomes larger than when the circulating current is not generated.

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