Presumption system

Abstract

To estimate a current value of a power storage device with high precision.SOLUTION: An estimation system includes a battery 5, an inverter 20, a motor 25, a current sensor 30u, and an ECU 100. The inverter 20 includes an upper arm circuit 22u and a lower arm circuit 23u, an upper arm circuit 22v and a lower arm circuit 23v, and an upper arm circuit 22w and a lower arm circuit 23w. Modes of the inverter 20 include a first mode in which the upper arm circuit 22u, the lower arm circuit 23v, and the lower arm circuit 23w are on, and a second mode in which the lower arm circuit 23u, the upper arm circuit 23v, and the upper arm circuit 23w are on. The ECU 100 executes an estimation process of estimating a current value of the battery 5. The estimation process includes a first process of estimating the current value in accordance with a detection value obtained by the current sensor 30u when the inverter 20 is in the first mode or the second mode.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an estimation system, and more particularly to an estimation system for estimating a current value of a power storage device.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2006-20401 (Patent Document 1) discloses a battery management system. This system includes a battery (power storage device), a three-phase AC motor, a number of sensors, and a control unit. Each sensor detects a corresponding physical quantity such as an accelerator opening, a vehicle speed, a rotation speed of the three-phase AC motor, and a voltage between terminals of the battery. The control unit calculates an estimated value of the battery current according to the detected values of these physical quantities.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The detected value of each sensor may include errors such as an offset error and a gain error. When the estimated value is calculated using a number of detected values as described above, this estimated value is affected by a number of errors respectively included in the number of detected values. This leads to a decrease in the accuracy of the estimated value.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide an estimation system for accurately estimating a current value of a power storage device.

Means for Solving the Problems

[0006] The estimation system of the present disclosure includes a power storage device, a first three-phase inverter, and a first three-phase AC motor. The first three-phase inverter is connected to the power storage device and includes a first leg circuit, a second leg circuit, and a third leg circuit. The first three-phase AC motor is connected to the first three-phase inverter. Each of the first leg circuit, the second leg circuit, and the third leg circuit includes an upper arm circuit and a lower arm circuit that is turned on and off complementarily to the upper arm circuit. The modes of the first three-phase inverter include a first mode in which the upper arm circuit of the first leg circuit, the lower arm circuit of the second leg circuit, and the lower arm circuit of the third leg circuit are on, and a second mode in which the lower arm circuit of the first leg circuit, the upper arm circuit of the second leg circuit, and the upper arm circuit of the third leg circuit are on. The estimation system further includes a first current sensor and a processing device. The first current sensor detects an alternating current flowing between the first-phase coil of the first three-phase AC motor and the first leg circuit. The processing device executes an estimation process for estimating the current value of the power storage device. The estimation process includes a first process of estimating the current value according to the detection value of the first current sensor when the mode of the first three-phase inverter is the first mode or the second mode.

[0007] When the mode of the inverter is the first mode, a first closed-loop circuit is formed by the upper arm circuit of the first leg circuit, the neutral point of the first three-phase AC motor, the lower arm circuits of the second leg circuit and the third leg circuit, and the power storage device. Similarly, when the mode of the inverter is the second mode, a second closed-loop circuit is formed by the lower arm circuit of the first leg circuit, the neutral point of the first three-phase AC motor, the upper arm circuits of the second leg circuit and the third leg circuit, and the power storage device. With the above configuration, in the first closed-loop circuit or the second closed-loop circuit, the current value is estimated on the assumption that the detection value of the first current sensor is equal to the current value of the power storage device. Thereby, only the detection value of the first current sensor is sufficient for estimating the current value, and the detection values of a large number of sensors are not required. As a result, a situation in which the estimation accuracy of the current value is reduced due to the use of the detection values of a large number of sensors is avoided. Therefore, the current value of the power storage device can be accurately estimated.

[0008] Preferably, the first process includes a process of estimating a current value according to a peak value of a detected value of the first current sensor.

[0009] Preferably, the estimation system further includes a second current sensor that detects an alternating current flowing between the second-phase coil of the first three-phase AC motor and the second leg circuit. The modes of the first three-phase inverter include a third mode in which the lower arm circuit of the first leg circuit, the upper arm circuit of the second leg circuit, and the lower arm circuit of the third leg circuit are on, and a fourth mode in which the upper arm circuit of the first leg circuit, the lower arm circuit of the second leg circuit, and the upper arm circuit of the third leg circuit are on. The estimation process further includes a second process of estimating a current value according to a detected value of the second current sensor when the mode of the first three-phase inverter is the third mode or the fourth mode.

[0010] Preferably, the second process includes a process of estimating a current value according to a peak value of a detected value of the second current sensor after the first current sensor detects a peak value.

[0011] The first process and the second process are each executed once per cycle of the alternating current (first alternating current) flowing through the first phase of the first three-phase AC motor and the alternating current (second alternating current) flowing through the second phase. Thereby, the current value is determined not only once per cycle of the first alternating current but also once per cycle of the second alternating current. As a result, the processing device can use more peak values as estimated values of the current value than when only the first process is executed. The processing device can confirm that neither the first current sensor nor the second current sensor is faulty, for example, based on the difference between the maximum value and the minimum value of the absolute values of these peak values being less than a predetermined minute value. Thereby, the processing device can confirm that the reliability of the estimated value based on the detected values of the first current sensor and the second current sensor is high.

[0012] Preferably, the estimation system further includes at least one electrical device each configured to operate by receiving power from a power storage device. The processing device executes the first process when the at least one electrical device stops.

[0013] When at least one of the above electrical devices operates, power (current flows) is supplied from the power storage device not only to the inverter but also to at least one of the above electrical devices. As a result, the detected value of the first current sensor is not necessarily equal to the current value of the power storage device. With the above configuration, the first estimation process is executed in a state where no current flows from the power storage device to at least one of the above electrical devices. Thereby, the estimation accuracy of the current value of the power storage device can be further improved.

[0014] Preferably, at least one of the above electrical devices includes an auxiliary machine configured to operate with the output voltage of the power storage device, a power converter configured to step down the output voltage, and a second three-phase inverter connected in parallel to the first three-phase inverter with respect to the power storage device.

[0015] Preferably, the estimation system further includes a boost chopper circuit connected between the power storage device and the first three-phase inverter. The boost chopper circuit includes an upper arm circuit and a lower arm circuit. The processing device executes the first process when the conduction state of the upper arm circuit of the boost chopper circuit and the non-conduction state of the lower arm circuit of the boost chopper circuit are maintained and the load of the first three-phase AC motor is constant.

[0016] When the conduction state of the upper arm circuit and the non-conduction state of the lower arm circuit are maintained and the load of the three-phase AC motor is constant, the current of the first closed-loop circuit or the second closed-loop circuit does not change due to the reactor of the boost chopper circuit. With the above configuration, even when the vehicle is equipped with a boost chopper circuit, the current value of the power storage device can be accurately estimated by the first estimation process.

[0017] Preferably, the estimation system further includes a current detection unit that detects a current value. The processing device is further configured to execute a failure diagnosis process for diagnosing the presence or absence of a failure of the current detection unit by comparing the detected value of the first current sensor with the detected value of the current detection unit.

[0018] With the above configuration, it is possible to accurately diagnose the presence or absence of a failure in the current detection unit.

Advantages of the Invention

[0019] According to the present disclosure, the current value of the power storage device can be accurately estimated.

Brief Description of the Drawings

[0020]

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Mode for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals and their description will not be repeated. The embodiment describes an example in which an estimation system is mounted on a vehicle.

[0022] FIG. 1 is an overall configuration diagram of a vehicle equipped with an estimation system according to the embodiment. This vehicle is a four-wheel drive capable battery electric vehicle (BEV).

[0023] Referring to FIG. 1, the vehicle 1 includes a battery 5, a monitoring unit 7, an SMR (System Main Relay) 8, a capacitor C1, a voltage sensor 9, inverters 20, 70, motors 25, 75, and sensor units 27, 76. The vehicle 1 further includes current sensors 30u, 30v, 30w, an HMI (Human Machine Interface) device 50, an accelerator pedal 52, a brake pedal 53, and a start switch (ST-SW) 55. The vehicle 1 further includes a high-voltage auxiliary machine 80, a DC-DC converter 90, and a low-voltage auxiliary machine 92.

[0024] The battery 5, the monitoring unit 7, the SMR 8, the voltage sensor 9, the inverters 20, 70, the motors 25, 75, the sensor units 27, 76, the current sensors 30u, 30v, 30w, the HMI device 50, the high-voltage auxiliary machine 80, the DC-DC converter 90, and the low-voltage auxiliary machine 92 correspond to an example of the "estimation system" of the present disclosure.

[0025] The battery 5 is a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. The positive electrode of the battery 5 is connected to the positive electrode line PL1 via the SMR 8. The negative electrode of the battery 5 is connected to the negative electrode line NL via the SMR 8. The battery 5 corresponds to an example of the "power storage device" of the present disclosure.

[0026] The monitoring unit 7 includes a current sensor 7a, a voltage sensor 7b, and a temperature sensor 7c. The current sensor 7a, the voltage sensor 7b, and the temperature sensor 7c detect the current IB, the voltage VB, and the temperature TB of the battery 5, respectively. The current sensor 7a corresponds to an example of the "current detection unit" of the present disclosure.

[0027] The SMR 8 is connected to the battery 5. The capacitor C1 is connected between the positive electrode line PL1 and the negative electrode line NL, and smoothes the voltage fluctuation between the positive electrode line PL1 and the negative electrode line NL. The voltage sensor 9 detects the voltage VH between the positive electrode line PL1 and the negative electrode line NL.

[0028] The inverter 20 is a three-phase inverter and is connected to the battery 5 via the SMR8. The inverter 20 includes a leg circuit 21u, a leg circuit 21v, and a leg circuit 21w. Each of the leg circuit 21, the leg circuit 21v, and the leg circuit 21w includes an upper arm circuit 22 and a lower arm circuit 23 that is turned on and off complementarily to the upper arm circuit 22.

[0029] The upper arm circuits 22 of the leg circuit 21u, the leg circuit 21v, and the leg circuit 21w are also represented as upper arm circuits 22u, 22v, and 22w, respectively. The lower arm circuits 23 of the leg circuit 21u, the leg circuit 21v, and the leg circuit 21w are also represented as lower arm circuits 23u, 23v, and 23w, respectively.

[0030] The midpoint between the upper arm circuit 22u and the lower arm circuit 23u is connected to the U-phase terminal of the motor 25. The midpoint between the upper arm circuit 22v and the lower arm circuit 23v is connected to the V-phase terminal of the motor 25. The midpoint between the upper arm circuit 22w and the lower arm circuit 23w is connected to the W-phase terminal of the motor 25.

[0031] The upper arm circuit 22u includes a diode D1 and a switching element Q1. The lower arm circuit 23u includes a diode D2 and a switching element Q2. The upper arm circuit 22v includes a diode D3 and a switching element Q3. The lower arm circuit 23v includes a diode D4 and a switching element Q4. The upper arm circuit 22w includes a diode D5 and a switching element Q5. The lower arm circuit 23w includes a diode D6 and a switching element Q6. Each of the switching elements Q1 to Q6 is, for example, an IGBT (Insulated Gate Bipolar Transistor) or a MOS (Metal Oxide Semiconductor) transistor. The diodes D1 to D6 are connected in anti-parallel to the switching elements Q1 to Q6, respectively.

[0032] The inverter 20 is configured to convert DC power supplied from the battery 5 via the SMR8 into AC power and supply it to the motor 25. The inverter 20 is also configured to convert AC power generated by the motor 25 into DC power and supply it to the battery 5. The operation of the inverter 20 will be described in detail later.

[0033] The motor 25 is a three-phase AC motor connected to the inverter 20 and the drive wheels (front wheels not shown in this example) of the vehicle 1. The motor 25 receives three-phase AC power from the inverter 20 and rotates to generate a driving force for the vehicle 1 to travel. The U-phase coil LU, V-phase coil LV, and W-phase coil LW of the motor 25 are connected to each other via the neutral point NP. The U-phase resistance, V-phase resistance, and W-phase resistance of the motor 25 are also represented as the U-phase resistance RU, V-phase resistance RV, and W-phase resistance RW, respectively.

[0034] The current sensors 30u, 30v, and 30w detect the currents Iu, Iv, and Iw, respectively. The current Iu is an alternating current flowing between the U-phase coil LU and the leg circuit 21u. The current Iv is an alternating current flowing between the V-phase coil LV and the leg circuit 21v. The current Iw is an alternating current flowing between the W-phase coil LW and the leg circuit 21w.

[0035] The HMI device 50 notifies various information to the user of the vehicle 1 and receives various user operations. The user operations include operations for instructing the activation or stop of the high-voltage auxiliary machine 80 or the low-voltage auxiliary machine 92. Each of the accelerator pedal 52 and the brake pedal 53 is operated to set a required value for the driving force (traveling speed) of the vehicle 1.

[0036] The start switch 55 is operated by the user to switch the start state and stop state of the traveling system of the vehicle 1. The start state of the traveling system corresponds to the closed state of the SMR8. The stop state of the traveling system corresponds to the open state of the SMR8. The sensor unit 27 detects the rotational speed ω, torque TR, and each phase voltage of the motor 25.

[0037] The inverter 70 is a three-phase inverter. The inverter 70 is connected in parallel with the inverter 20 to the battery 5 and is configured to operate by receiving power from the battery 5. The inverter 70 includes three leg circuits (not shown), similar to the inverter 20. The inverter 70 is an example of the "electrical equipment" of the present disclosure.

[0038] The motor 75 is a three-phase AC motor. The motor 75 is connected to the inverter 70 and operates (rotates) by receiving three-phase AC power supplied from the inverter 70. The motor 75 is configured to drive the rear wheels (not shown) to generate the driving force for the vehicle 1 to travel. In this example, while the driving force derived from the motor 25 is used as the main driving force for travel, the driving force derived from the motor 75 is used when the vehicle 1 is in four-wheel drive. The sensor unit 76 detects the rotational speed, torque, each phase current (currents Iua, Iva, Iwa), and each phase voltage of the motor 75.

[0039] The high-voltage auxiliary machine 80 is an air conditioner in this example, but it may also be a battery heater. The high-voltage auxiliary machine 80 is configured to operate at the output voltage of the battery 5 by receiving power from the battery 5. The high-voltage auxiliary machine 80 is an example of the "electrical equipment" of the present disclosure. The high-voltage auxiliary machine 80 is provided with a current sensor 81. The current sensor 81 is configured to detect the input current IC1 of the high-voltage auxiliary machine 80. When the high-voltage auxiliary machine 80 stops, the input current IC1 is zero.

[0040] The DC-DC converter 90 is a power converter configured to operate by receiving power from the battery 5. The DC-DC converter 90 steps down the output voltage of the battery 5 (for example, to 12V). The DC-DC converter 90 is an example of the "electrical equipment" of the present disclosure. The DC-DC converter 90 is provided with a current sensor 91. The current sensor 91 is configured to detect the input current IC2 of the DC-DC converter 90. When the DC-DC converter 90 stops, the input current IC2 is zero.

[0041] The low-voltage auxiliary machine 92 is, for example, an audio device. The low-voltage auxiliary machine 92 operates with the voltage stepped down by the DC-DC converter 90.

[0042] The ECU 100 includes a processor 102 and a memory 104. The processor 102 is, for example, a CPU (Central Processing Unit) and executes various arithmetic processes. The memory 104 includes a ROM (Read Only Memory) and a RAM (Random Access Memory) (both not shown). The ROM stores programs executed by the processor 102.

[0043] The ECU 100 controls various devices of the vehicle 1, such as the SMR 8, the inverters 20, 70, the motors 25, 75, the HMI device 50, the high-voltage auxiliary machine 80, the DC-DC converter 90, and the low-voltage auxiliary machine 92. The ECU 100 controls the above various devices according to the detection values of the monitoring unit 7, the voltage sensors 9, the sensor units 27, 76, and the current sensors 30u, 30v, 30w, 81, 91, the operation amount of the accelerator pedal 52 or the brake pedal 53, or the user operation on the HMI device 50 or the start switch 55. The ECU 100 estimates the SOC (State Of Charge) of the battery 5 according to the detection value of the monitoring unit 7.

[0044] The ECU 100 is configured to be able to stop the high-voltage auxiliary machine 80 when the power consumption of the high-voltage auxiliary machine 80 is less than the reference consumption. Similarly, the ECU 100 is configured to be able to stop the DC-DC converter 90 when the power consumption of the low-voltage auxiliary machine 92 is less than the reference consumption. The value indicating the reference consumption is stored in the memory 104.

[0045] When the required value of the driving force of the vehicle 1 is less than the reference required value (for example, when the opening degree of the accelerator pedal 52 is less than a predetermined opening degree), the ECU 100 is configured to be able to stop the inverter 70 among the inverters 20 and 70. When the inverter 70 is stopped, the vehicle 1 travels by two-wheel drive as long as the inverter 20 is operating. The value indicating the reference required value is stored in the memory 104.

[0046] The ECU 100 turns on and off each of the upper arm circuits 22u, 22v, and 22w. Turning on and off the upper arm circuits 22u, 22v, and 22w corresponds to turning on and off the switching elements Q1, Q3, and Q5, respectively. The ECU 100 turns on and off each of the lower arm circuits 23u, 23v, and 23w. Turning on and off the lower arm circuits 23u, 23v, and 23w corresponds to turning on and off the switching elements Q2, Q4, and Q6, respectively. The ECU 100 turns on and off the lower arm circuits 23u, 23v, and 23w complementarily to the upper arm circuits 22u, 22v, and 22w, respectively.

[0047] The ECU 100 controls the on and off of the switching elements Q1 to Q6 through the signals S1 to S6, thereby controlling the inverter 20.

[0048] The operation of the inverter 20 will be described with reference to FIGS. 2 to 7. In the description of FIGS. 2 to 7, it is assumed that the SMR 8 is in the closed state, and the inverter 70 (motor 75), the high-voltage auxiliary machine 80, and the DC-DC converter 90 are stopped. As described below, the modes (switching states) of the inverter 20 include modes A to F.

[0049] FIG. 2 is a diagram for explaining the conduction states of the inverter 20 and the motor 25 in mode A. Referring to FIG. 2, in mode A, the upper arm circuits 22u, 22w, and the lower arm circuit 23v are on, and the upper arm circuit 22v and the lower arm circuits 23u, 23w are off. A closed-loop circuit composed of the upper arm circuit 22u, the upper arm circuit 22w, the neutral point NP, the lower arm circuit 23v, and the battery 5 is also represented as the "loop circuit CLA" (the thick line part in FIG. 2). Mode A corresponds to an example of the "fourth mode" of the present disclosure.

[0050] FIG. 3 is a diagram for explaining the conduction states of the inverter 20 and the motor 25 in mode B. Referring to FIG. 3, in mode B, the upper arm circuit 22u and the lower arm circuits 23v, 23w are on, and the upper arm circuits 22v, 22w and the lower arm circuit 23u are off. A closed-loop circuit composed of the upper arm circuit 22u, the neutral point NP, the lower arm circuit 23v, the lower arm circuit 23w, and the battery 5 is also represented as the "loop circuit CLB" (the thick line part in FIG. 3). Mode B corresponds to an example of the "first mode" of the present disclosure.

[0051] FIG. 4 is a diagram for explaining the conduction states of the inverter 20 and the motor 25 in mode C. Referring to FIG. 4, in mode C, the upper arm circuits 22u, 22v and the lower arm circuit 23w are on, and the upper arm circuit 22w and the lower arm circuits 23u, 23v are off. A closed-loop circuit composed of the upper arm circuits 22u, 22v, the neutral point NP, the lower arm circuit 23w, and the battery 5 is also represented as the "loop circuit CLC" (the thick line part in FIG. 4).

[0052] FIG. 5 is a diagram for explaining the conduction states of the inverter 20 and the motor 25 in mode D. Referring to FIG. 5, in mode D, the upper arm circuit 22v and the lower arm circuits 23u and 23w are on, and the upper arm circuits 22u and 22w and the lower arm circuit 23v are off. A closed loop circuit composed of the upper arm circuit 22v, the neutral point NP, the lower arm circuits 23u and 23w, and the battery 5 is also referred to as a "loop circuit CLD" (the thick line portion in FIG. 5). Mode D corresponds to an example of the "third mode" of the present disclosure.

[0053] FIG. 6 is a diagram for explaining the conduction states of the inverter 20 and the motor 25 in mode E. Referring to FIG. 6, in mode E, the upper arm circuits 22v and 22w and the lower arm circuit 23u are on, and the upper arm circuit 22u and the lower arm circuits 23v and 23w are off. A closed loop circuit composed of the lower arm circuit 23u, the neutral point NP, the upper arm circuits 22v and 22w, and the battery 5 is also referred to as a "loop circuit CLE" (the thick line portion in FIG. 6). Mode E corresponds to an example of the "second mode" of the present disclosure.

[0054] FIG. 7 is a diagram for explaining the conduction states of the inverter 20 and the motor 25 in mode F. Referring to FIG. 7, in mode F, the upper arm circuit 22w and the lower arm circuits 23u and 23v are on, and the upper arm circuits 22u and 22v and the lower arm circuit 23w are off. A closed loop circuit composed of the upper arm circuit 22w, the neutral point NP, the lower arm circuits 23u and 23v, and the battery 5 is also referred to as a "loop circuit CLF" (the thick line portion in FIG. 7).

[0055] Modes A to F may be modes during power running or regeneration of the vehicle 1.

[0056] FIG. 8 is a diagram exemplifying changes in the phase currents of the motor 25 due to changes in the modes of the inverter 20. This figure also lists the relationship between the on-off states (switching patterns) of the switching elements Q1 to Q6 and each mode.

[0057] Referring to FIG. 8, in the lower part, the vertical axis indicates the magnitude of each phase current (current Iu, Iv or Iw), and the horizontal axis indicates time. The amplitude of each phase current is IA. Lines 210, 220, 230 schematically show how the currents Iu, Iv, Iw change with the change of the mode. When the magnitude of the current is positive, the current flows from the positive electrode of the battery 5 towards the neutral point NP. When the magnitude of the current is negative, the current flows from the neutral point NP towards the negative electrode of the battery 5. In this example, for ease of understanding, the distortion (harmonic component) of each phase current is not depicted.

[0058] FIG. 9 is a diagram for explaining the sensor error of the current sensor. Referring to FIG. 9, line 405 represents the relationship between the current detected by a certain current sensor and the upper and lower limits of the range within which the sensor error of this current sensor can occur. This current sensor is, for example, current sensors 30u, 30v, 30w, 81 or 91. The sensor error can include an offset error and a gain error. The offset error is the error from the ideal value (0) that is independent of the magnitude of the undetected current. The gain error is an error that increases as the magnitude of the undetected current increases. Width EW1 is the width of the range within which the sensor error of the above current sensor can occur.

[0059] Line 415 represents the relationship between the current detected by each of n (in this example, n = 2) current sensors when each current sensor detects the current and the upper and lower limits of the range within which the sum of the sensor errors of each current sensor can occur. Width EW2 is the width of the range within which the sum of these sensor errors can occur, and it is larger than width EW1. Thus, the more current sensors are used (the larger n is), the greater the influence of the sensor error becomes.

[0060] Referring back to FIG. 1, in order to accurately estimate the SOC of the battery 5, it is necessary that the error included in the detected value of the current IB is small. In order for such an error to be small, it is important that the current sensor 7a is not malfunctioning (is normal). One method of diagnosing the presence or absence of a malfunction of the current sensor 7a is to redundantly mount a battery current sensor (not shown) different from the current sensor 7a on the vehicle 1 and calculate the difference between the detected value of this redundant current sensor and the detected value of the current sensor 7a. When this difference is relatively small, the current sensor 7a is diagnosed as being normal. On the other hand, when the difference is relatively large, the current sensor 7a (or the redundant battery current sensor) is diagnosed as malfunctioning.

[0061] Mounting a redundant current sensor on the vehicle 1 to diagnose the presence or absence of a malfunction of the current sensor 7a causes an increase in cost. In order to avoid such an increase in cost, it is preferable to estimate the current IB without a redundant current sensor. By calculating the difference between the estimated value of the current IB and the detected value of the current IB (the detected value of the current sensor 7a), it is possible to diagnose the presence or absence of a malfunction of the current sensor 7a according to whether this difference is large or small.

[0062] In the embodiment, the ECU 100 is configured to execute an estimation process for estimating the current value (battery current value) of the battery 5 without depending on the detected value of the current sensor 7a. Estimating the battery current value corresponds to calculating the estimated value of the current IB. The ECU 100 executes the estimation process during the startup of the driving system of the vehicle 1.

[0063] Hereinafter, before explaining the estimation process by the ECU 100, an estimation method of the current IB by the ECU in the comparative example will be explained. In the comparative example, it is assumed that the SMR8 is in the closed state and all of the inverter 70 (motor 75), the high-voltage auxiliary machine 80, and the DC-DC converter 90 are operating.

[0064] The ECU of the comparative example estimates the current IB according to the following formula (1). (Estimated value of current IB) = (Detected value of input current IC1) + (Detected value of input current IC2) + (Calculated value of estimated current of inverter 20) + (Calculated value of estimated current of inverter 70)…(1) The third term on the right side of Equation (1) corresponds to the difference between the output of motor 25 (the product of the rotational speed ω and torque TR) and the power loss of motor 25, divided by the detected value of voltage sensor 9 (voltage VH). The power loss is calculated according to the detected values of the phase currents (currents Iu, Iv, Iw) of motor 25, the phase resistance values, and the rotational speed ω. Similarly, the fourth term on the right side corresponds to the difference between the output of motor 75 (the product of the rotational speed and torque) and the power loss of motor 75, divided by VH. The power loss is calculated according to the detected values of the phase currents of motor 75, the phase resistance values, and the rotational speed.

[0065] To estimate current IB as in the comparative example, the detected values of a large number of sensors including current sensors 30u~30w, 81, 91, and sensor units 27, 76 are required. As described above, the detected value of each sensor may include errors such as offset error and gain error. When the battery current value is estimated using a large number of detected values as in the comparative example, the estimated value is affected by the large number of sensor errors included in each detected value. As a result, the errors caused by each sensor error are stacked in the estimated value, and the accuracy of the estimated value of current IB may decrease. Therefore, in the comparative example, it may not be possible to accurately estimate current IB.

[0066] Hereinafter, with reference to FIGS. 1 to 3, FIGS. 5 and 6 again, the estimation process of current IB executed by ECU 100 in the embodiment will be described.

[0067] When the mode of inverter 20 is in mode B (FIG. 3) or mode E (FIG. 6), ECU 100 executes a first process of estimating the battery current value according to the detected value of current sensor 30u (current Iu). The first process is included in the aforementioned estimation process. The first process corresponds to estimating current IB according to, for example, the following Equation (2).

[0068] (Estimated value of current IB) = (Detected value of input current IC1) + (Detected value of input current IC2) + (Detected value of current Iu) + (Detected value of current Iua)…(2) Equation (2) is different from Equation (1) of the comparative example in that the detected value of current Iu and the detected value of current Iua are used instead of the calculated value of the estimated current of the inverters 20 and 70. The fourth term on the right side of Equation (2) (detected value of current Iua) may be expressed as the value of the input / output current of the inverter 70 determined based on the detected values of currents Iua, Iva, and Iwa.

[0069] In the embodiment, an example will be mainly described in which the ECU 100 executes the first process while, for example, the inverter 70 (motor 75), the high-voltage auxiliary machine 80, and the DC-DC converter 90 are stopped. In this case, since the first, second, and fourth terms on the right side of Equation (2) are not required to estimate the current IB, Equation (2) is represented by the following Equation (3).

[0070] (Estimated value of current IB) = (Detected value of current Iu)…(3) According to Equation (3), in the loop circuit CLB (Fig. 3) or the loop circuit CLE (Fig. 6), the battery current value is estimated on the assumption that the detected value of the current sensor 30u is equal to the battery current value. As a result, the detected value of the current sensor 30v is used as the battery current value as it is. That is, only the detected value of the current sensor 30u is sufficient to estimate the battery current value, and the detected values of many other sensors are not required. As a result, a situation in which the estimation accuracy of the battery current value is reduced due to the use of the detected values of many sensors is avoided. Therefore, the battery current value can be accurately estimated.

[0071] Similarly, when the mode of the inverter 20 is in mode D (Fig. 5) or mode A (Fig. 2), the ECU 100 can also execute a second process of estimating the battery current value according to the detected value of the current sensor 30v (current Iv). The second process is included in the aforementioned estimation process. The second process corresponds to estimating the current IB according to, for example, the following Equation (4).

[0072] (Estimated value of current IB) = (Detected value of input current IC1) + (Detected value of input current IC2) + (Detected value of current Iv) + (Detected value of current Iva)…(4) The fourth term on the right side of Equation (4) may be expressed as the value of the input / output current of inverter 70 determined based on the detected values of currents Iua, Iva, and Iwa.

[0073] ECU 100 executes the second process in a state where, for example, inverter 70, high-voltage auxiliary machine 80, and DC-DC converter 90 are stopped. In this case, Equation (4) is expressed by the following Equation (5).

[0074] (Estimated value of current IB) = (Detected value of current Iv)…(5) According to Equation (5), in loop circuit CLD (Fig. 5) or loop circuit CLA (Fig. 2), the battery current value is estimated on the assumption that the detected value of current sensor 30v is equal to the battery current value. Thus, the battery current value can be accurately estimated for the same reason as in the case of the first process.

[0075] Similarly, when the mode of inverter 20 is in mode C (Fig. 4) or mode F (Fig. 7), ECU 100 can also execute a third process of estimating the battery current value according to the detected value (current Iw) of current sensor 30w.

[0076] The first process, the second process, and the third process respectively correspond to processes of estimating the battery current value according to the peaks (peak values) of the detected values of current sensors 30u, 30v, and 30w. Hereinafter, this point will be described in detail.

[0077] Fig. 10 is a diagram for explaining the process in which ECU 100 estimates the battery current value according to the peak values of current sensors 30u, 30v, and 30w. This figure is based on Fig. 8.

[0078] Referring to FIG. 10, lines 210, 220, and 230 are the same as those described in FIG. 8. Line 300 schematically shows the battery current value (value of direct current). Peak values Iup+, Ivp+, and Iwp+ are the positive peak values of the detection values of current sensors 30u, 30v, and 30w, respectively.

[0079] At time ta, current sensor 30u detects peak value Iup+ (line 210). ECU 100 determines peak value Iup+ as the estimated value ESV of the battery current value. After time ta, while current Iu decreases, current Iv increases (line 220).

[0080] At time tb, current sensor 30v detects peak value Ivp+. ECU 100 determines peak value Ivp+ as the estimated value ESV. In this case, the aforementioned second process corresponds to a process of estimating the battery current value according to peak value Ivp+ of the detection value of current sensor 30v after current sensor 30u detects peak value Iup+ at time ta. After time tb, while current Iv decreases, current Iw increases (line 230).

[0081] At time tc, current sensor 30w detects peak value Iwp+. ECU 100 determines peak value Iwp+ as the estimated value ESV. After time tc, while current Iw decreases, current Iu increases.

[0082] ECU 100 also executes estimation processing according to peak values Iup-, Ivp-, and Iwp- at times tp, tq, and tr, respectively. Peak values Iup-, Ivp-, and Iwp- are the negative peak values of the detection values of current sensors 30u, 30v, and 30w, respectively. In this case, at time tp, the estimated value ESV is peak value Ivp-. At time tq, the estimated value ESV is peak value Iwp-. At time tr, the estimated value ESV is peak value Iup-.

[0083] In this way, the ECU 100 determines the peak values Iup+, Ivp+, Iwp+, Iup-, Ivp-, Iwp- as estimated values ESV at times ta, tb, tc, tp, tq, tr, respectively. Thereby, the discrepancy between the battery current value (line 300) and the estimated value ESV can be reduced as much as possible. Each of the peak values Iup+, Ivp+, Iwp+, Iup-, Ivp-, Iwp- corresponds to an example of the "peak value" of the present disclosure.

[0084] The estimated value ESV transitions among the peak values Ivp-, Iup+, Iwp-, Ivp+, Iup-, Iwp+ in this order. In reality, since the battery current value changes depending on the time change of the SOC of the battery 5, these peak values can also change depending on the time t.

[0085] In this example, the aforementioned first process, second process, and third process are each executed every half cycle of the currents Iu, Iv, Iw (for example, the first process is executed at times ta, tr, the second process is executed at times tp, tb, and the third process is executed at times tq, tc). Thereby, the estimated value ESV is determined not only every half cycle of the current Iu but also every half cycle of the current Iv and every half cycle of the current Iw. As a result, the ECU 100 can use more peak values as the estimated value ESV than when only the first process is executed. The ECU 100 can confirm that none of the current sensors 30u, 30v, 30w are malfunctioning based on, for example, the difference between the maximum value and the minimum value of the absolute values of the peak values Ivp-, Iup+, Iwp-, Ivp+, Iup-, Iwp+ being less than a predetermined minute value (if this difference is greater than the minute value, there is a possibility that at least one current sensor is malfunctioning). Thereby, the ECU 100 can confirm that the reliability of the estimated value ESV based on the detected values of the current sensors 30u, 30v, 30w is high. The above-mentioned minute value is stored in the memory 104.

[0086] The ECU 100 is also configured to execute a failure diagnosis process for diagnosing the presence or absence of a failure of the current sensor 7a by comparing, for example, the detected value of the current sensor 30u (for example, the peak value Iup+) with the detected value of the current sensor 7a (for example, determining whether the difference between these detected values is less than a threshold value).

[0087] For example, when the above difference is greater than or equal to the threshold value, since the detected value of the battery current value deviates from the estimated value, there is a possibility that the current sensor 7a has failed. On the other hand, when the difference is less than the threshold value, since the detected value of the battery current value approximates the estimated value, the current sensor 7a is considered to be normal. In the embodiment, since the estimated value of the battery current value is calculated with high accuracy, the presence or absence of a failure of the current sensor 7a can be accurately diagnosed. Note that the failure diagnosis process is completed in a few seconds.

[0088] The ECU 100 may execute the failure diagnosis process, for example, when the difference between the maximum value and the minimum value of the absolute values of the peak values Ivp-, Iup+, Iwp-, Ivp+, Iup-, Iwp+ is less than the aforementioned minute value. Thereby, when the reliability of the estimated value ESV is high, the presence or absence of a failure of the current sensor 7a is diagnosed. As a result, the reliability of the failure diagnosis process can be guaranteed.

[0089] FIG. 11 is a diagram schematically showing the data stored in the memory 104. Referring to FIG. 11, the data 500 represents the relationship between the current sensor (target sensor) used for determining the estimated value ESV and the mode of the inverter 20. The target sensor is determined for each mode of the inverter 20.

[0090] Referring to FIG. 1 again, in the embodiment, the ECU 100 executes an estimation process when at least one of the inverter 70, the high-voltage auxiliary machine 80, and the DC-DC converter 90 stops.

[0091] When the inverter 70, the high-voltage auxiliary machine 80, and the DC-DC converter 90 are operating, power is supplied not only from the battery 5 to the inverter 20 (motor 25), but also to the inverter 70, the high-voltage auxiliary machine 80, and the DC-DC converter 90 (input currents IC1 and IC2 flow into the inverter 70). Therefore, while at least any one of the inverter 70, the high-voltage auxiliary machine 80, and the DC-DC converter 90 is operating, the detected value of the current sensor 30u is not necessarily equal to the battery current value.

[0092] As described above, by executing the estimation process when at least one of the inverter 70, the high-voltage auxiliary machine 80, and the DC-DC converter 90 stops, it is possible to estimate the battery current value in a state where at least one of the input currents of the inverter 70, input currents IC1 and IC2, is not flowing. As a result, at least one of the detected value of the input current of the inverter 70, the detected value of the current sensor 81, and the detected value of the current sensor 81 becomes unnecessary. Therefore, compared with an example in which the battery current value is estimated based on the detected values of the current sensors 30u, 81, and 91 and the detected value of the sensor unit 76 in a state where all of the input current of the inverter 70, input currents IC1 and IC2 are flowing (specifically, an example in which the value of the current IB is estimated as the sum of the detected values of the input current of the inverter 70, input currents IC1 and IC2, and the detected value of the current Iu), the number of sensors used for estimating the battery current value can be reduced. As a result, the battery current value can be accurately estimated.

[0093] Preferably, the ECU 100 executes the estimation process when all of the inverter 70, the high-voltage auxiliary machine 80, and the DC-DC converter 90 stop. As a result, the stop process is executed in a state where none of the input current of the inverter 70, input currents IC1 and IC2 are flowing. As a result, the battery current value can be estimated under the assumption that the detected value of the current sensor 30u is equal to the battery current value. Therefore, the number of sensors used for estimating the battery current value can be minimized, thereby further improving the accurate estimation of the battery current value.

[0094] When at least one of the inverter 70 (motor 75), the high-voltage auxiliary machine 80, and the DC-DC converter 90 is operating, the ECU 100 executes an estimation process according to, for example, Equation (2) or Equation (4). By executing the estimation process in this way, it is possible to reduce the number of sensors used for estimating the battery current value as compared with a comparative example in which the estimated current of the inverter 20 (the third term on the right side of Equation (1)) is calculated.

[0095] FIG. 12 is a diagram for explaining the advantages of the embodiment. Referring to FIG. 12, this example shows the estimation error of the battery current value in each of the comparative example and the embodiment.

[0096] In the comparative example, the estimation error ER1 includes a noise-derived error NE1 and a sensor-derived error SE1. The noise-derived error NE1 is derived from, for example, the switching noise of the switching elements Q1 to Q6. Since the battery current value is estimated according to Equation (1), the sensor-derived error SE1 includes errors SE11 to SE15. The error SE11 is derived from the sensor error of the voltage sensor 9 with respect to the voltage VH. The error SE12 is derived from the sensor error of the sensor unit 27 with respect to the rotational speed ω. The error SE13 is derived from the sensor error of the sensor unit 27 with respect to the torque TR. The error SE14 is derived from the calculation error of the power loss of the inverter 20 caused by the sensor error of the current sensors 30u to 30w. The error SE15 is derived from the sensor error of the current sensors 81 and 91.

[0097] In the embodiment, the estimation error ER2 includes a noise-derived error NE2 and a sensor-derived error SE2. The noise-derived error NE1 is derived from, for example, switching noise as in the comparative example. The sensor-derived error SE2 is the sensor error of the aforementioned target sensor (for example, the current sensor 30u). In this example, no sensors other than the target sensor are required to estimate the battery current value. Therefore, an increase in the sensor error due to an increase in the number of sensors can be prevented. As a result, the battery current can be estimated with higher accuracy than in the case of the comparative example (ER2 < ER1).

[0098] FIG. 13 is a flowchart for explaining an example of a procedure of processing executed by the ECU 100 in the embodiment. This flowchart is executed at predetermined intervals while the driving system is activated. Hereinafter, steps are abbreviated as "S".

[0099] Referring to FIG. 13, the ECU 100 executes an estimation process for estimating a battery current value (S150), and executes a failure diagnosis process according to the result of the estimation process (S160). After S160, the process proceeds to return. Hereinafter, the procedures of S150 and S160 will be described in detail.

[0100] FIG. 14 is a flowchart illustrating the procedure of the estimation process. FIGS. 2 to 7, FIG. 10, and FIG. 11 are appropriately referred to in the description of this flowchart.

[0101] Referring to FIG. 14, the ECU 100 switches the process according to the mode of the inverter 20 using the data 500 (S152).

[0102] When the mode of the inverter 20 is mode A, the ECU 100 determines that the target sensor is the current sensor 30v, and estimates the battery current value according to the peak value Ivp- (S153). In this example, the ECU 100 determines the peak value Ivp- as the estimated value ESV.

[0103] When the mode of the inverter 20 is mode B, the ECU 100 determines that the target sensor is the current sensor 30u, and estimates the battery current value according to the peak value Iup+ (S154). In this example, the ECU 100 determines the peak value Iup+ as the estimated value ESV.

[0104] When the mode of the inverter 20 is mode C, the ECU 100 determines that the target sensor is the current sensor 30w, and estimates the battery current value according to the peak value Iwp- (S155). In this example, the ECU 100 determines the peak value Iwp- as the estimated value ESV.

[0105] When the mode of the inverter 20 is mode D, the ECU 100 determines that the target sensor is the current sensor 30v, and estimates the battery current value according to the peak value Ivp+ (S156). In this example, the ECU 100 determines the peak value Ivp+ as the estimated value ESV.

[0106] When the mode of the inverter 20 is mode E, the ECU 100 determines that the target sensor is the current sensor 30u, and estimates the battery current value according to the peak value Iup- (S157). In this example, the ECU 100 determines the peak value Iup- as the estimated value ESV.

[0107] When the mode of the inverter 20 is mode F, the ECU 100 determines that the target sensor is the current sensor 30w, and estimates the battery current value according to the peak value Iwp+ (S158). In this example, the ECU 100 determines the peak value Iwp+ as the estimated value ESV.

[0108] FIG. 15 is a flowchart illustrating the procedure of the fault diagnosis process. Referring to FIG. 15, the ECU 100 acquires the detected value of the current IB from the current sensor 7a (S162).

[0109] The ECU 100 determines whether the difference Diff between the estimated value ESV and the detected value of the current IB is less than the reference value (S164). If the difference Diff is less than the reference value (YES in S164), the ECU 100 diagnoses that the current sensor 7a is normal (S166). If the difference Diff is greater than or equal to the reference value (NO in S164), the ECU 100 diagnoses that the current sensor 7a may be faulty (S168). After S166 or S168, the process proceeds to "Return" in FIG. 13.

[0110] FIG. 16 is a flowchart for explaining another example of the procedure of the process executed by the ECU 100 in the embodiment. This flowchart is different from the flowchart of FIG. 13 in that S103 is added, but is the same as the flowchart of FIG. 13 in other respects.

[0111] Referring to FIG. 16, the ECU 100 executes a determination process (S103) for determining whether at least one of the inverter 70 (motor 75), the high-voltage auxiliary machine 80, and the DC-DC converter 90 has stopped.

[0112] FIG. 17 is a flowchart showing an example of the procedure of this determination process. Referring to FIG. 17, the ECU 100 determines whether at least one of the electric devices of the inverter 70, the high-voltage auxiliary machine 80, and the DC-DC converter 90 has stopped (S104). If the at least one electric device has stopped (YES in S104), the process proceeds to S150. If all of the inverter 70, the high-voltage auxiliary machine 80, and the DC-DC converter 90 are operating (NO in S104), the process transfers to "Return" in FIG. 16.

[0113] FIG. 18 is a flowchart showing another example of the procedure of the determination process. Referring to FIG. 18, this flowchart is different from the flowchart of FIG. 17 in that S105, S110, and S120 are executed instead of S104.

[0114] Referring to FIG. 18, the ECU 100 switches the process according to whether the inverter 70 has stopped (S105). Specifically, the ECU 100 determines whether the required value of the driving force for running is less than the reference required value according to the opening degree of the accelerator pedal 52 and the opening degree of the brake pedal 53, and switches the process according to the result of this determination. If the inverter 70 is operating (NO in S105), the process transfers to "Return" in FIG. 16. If the inverter 70 has stopped (YES in S105), the process proceeds to S110.

[0115] The ECU 100 switches the process according to whether the high-pressure auxiliary machine 80 is stopped (S110). Specifically, the ECU 100 switches the process according to whether the operation of the high-pressure auxiliary machine 80 is instructed using the HMI device 50. When the high-pressure auxiliary machine 80 is operating (NO in S110), the process proceeds to "Return". When the high-pressure auxiliary machine 80 is stopped (YES in S110), the process proceeds to S120.

[0116] The ECU 100 switches the process according to whether the DC-DC converter 90 is stopped (S120). Specifically, the ECU 100 switches the process according to whether the operation of the low-pressure auxiliary machine 92 is instructed using the HMI device 50. When the DC-DC converter 90 is operating (NO in S120), the process proceeds to "Return". When the DC-DC converter 90 is stopped (YES in S120), the process proceeds to S150.

[0117] In the example of FIG. 18, the ECU 100 determines whether all of the inverter 70, the high-pressure auxiliary machine 80, and the DC-DC converter 90 are stopped, and when all of these are stopped, executes the estimation process (S150) and the failure diagnosis process (S160).

[0118] If the vehicle does not include two or more inverters (traction motors), S105 may be omitted. In the embodiment, since the vehicle 1 includes two or more traction motors (motors 25, 75) (YES in S105), the process proceeds to S110.

[0119] Even when the high-pressure auxiliary machine 80 is operating, the ECU 100 may stop the high-pressure auxiliary machine 80 prior to the estimation process based on the fact that the power consumption of the high-pressure auxiliary machine 80 is less than the reference consumption. In this case, the process proceeds from S110 to S120. Similarly, even when the DC-DC converter 90 is operating, the ECU 100 may stop the DC-DC converter 90 prior to the estimation process based on the fact that the power consumption of the low-pressure auxiliary machine 92 is less than the reference consumption. In this case, the process proceeds from S120 to S150.

[0120] As described above, the failure diagnosis process is completed in a few seconds. Therefore, even when the ECU 100 stops at least one of the high-voltage auxiliary machine 80 and the DC-DC converter 90 (for example, all of these devices) as described above prior to the failure diagnosis process (estimation process), it does not need to stop the at least one device for a long period of time. Accordingly, a decrease in usability is avoided.

[0121] As described above, according to the embodiment, the battery current value can be accurately estimated. The embodiment is particularly effective when estimating the battery current value of a vehicle equipped with a plurality of motors such as the vehicle 1 (a four-wheel drive electric vehicle). Such a vehicle generally includes a large number of sensors. Estimating the battery current value based on the detection values of these sensors as in the comparative example may reduce the estimation accuracy. On the other hand, in the embodiment, even in such a vehicle, the battery current value can be estimated using a minimum necessary number of current sensors (for example, only the current sensors 30u, 30v, or 30w), thereby improving the estimation accuracy of the battery current value. As a result, it is possible to accurately diagnose the presence or absence of a failure of the current sensor 7a without redundant current sensors. Accordingly, an increase in the weight and cost of the vehicle 1 caused by mounting redundant current sensors on the vehicle 1 can be avoided.

[0122] [Modification Example of the Embodiment] FIG. 19 is an overall configuration diagram of a vehicle equipped with an estimation system according to this modification example. Referring to FIG. 19, the vehicle 1A is different from the vehicle 1 in that it further includes a boost chopper circuit 110.

[0123] The boost chopper circuit 110 is connected between the battery 5 and the inverter 20. The boost chopper circuit 110 receives the output voltage of the battery 5 as a voltage VL (described later) and boosts it. The boosted voltage is provided as the input voltage (voltage VH) of the inverter 20. The boost chopper circuit 110 is an example of a component of the "estimation system" of the present disclosure.

[0124] The boost chopper circuit 110 includes a reactor L11, a capacitor C2, a voltage sensor 111, an upper arm circuit 112, and a lower arm circuit 114.

[0125] The reactor L1 is connected to the positive electrode line PL2. The capacitor C2 is connected between the positive electrode line PL2 and the negative electrode line NL. The voltage sensor 111 detects the voltage VL between the positive electrode line PL2 and the negative electrode line NL.

[0126] The upper arm circuit 112 includes a switching element Q11 and a diode D11. The diode D11 is connected in anti-parallel to the switching element Q11. The lower arm circuit 114 includes a switching element Q12 and a diode D12. The diode D12 is connected in anti-parallel to the switching element Q12.

[0127] The ECU 100 controls the on / off of the switching element Q11 and the switching element Q12. The ECU 100 is configured to be able to execute an upper arm on control that maintains the conduction state of the upper arm circuit 112 and the non-conduction state of the lower arm circuit 114. The upper arm on control corresponds to maintaining the switching elements Q11 and Q12 in the on and off states, respectively. The ECU 100 executes the upper arm control, for example, when the difference between the voltage VH and the voltage VL is smaller than a predetermined value (when the voltage VL approximates the voltage VH). According to the upper arm on control, it is possible to reduce the power loss in the switching elements Q11 and Q12 and prevent voltage fluctuations caused by dead time.

[0128] The ECU 100 is configured to execute the upper arm on control and execute the aforementioned first process and second process when the load of the motor 25 is constant. The ECU 100 can determine whether the load of the motor 25 is constant according to the torque TR.

[0129] Since the load on the motor 25 is constant, the current in the loop circuits CLA, CLB, CLC, CLD, CLE, or CLF (the input / output current of the inverter 20) is not affected by the fluctuation of the induced electromotive force of the reactor L1. As a result, in this modification, the battery current value can be accurately estimated in the same manner as in the embodiment.

[0130] FIG. 20 is a flowchart for explaining an example of the procedure of the process executed by the ECU 100 in this modification. Referring to FIG. 20, this flowchart is different from the flowchart of FIG. 16 in that S101 and S102 are added, but is the same as the flowchart of FIG. 16 in other respects.

[0131] The ECU 100 switches the process according to whether or not the upper arm on control is being executed (for example, whether the difference between the voltage VH and the voltage VL is less than a predetermined value). When the ECU 100 is not executing the upper arm on control (NO in S101), the process proceeds to return. When the ECU 100 is executing the upper arm on control (YES in S101), the process proceeds to S102.

[0132] The ECU 100 determines whether the load on the motor 25 is constant according to the torque TR (S102). When the load on the motor 25 is not constant (NO in S102), the process proceeds to return. When the load on the motor 25 is constant (YES in S102), the process proceeds to S103. In the flowchart of FIG. 20, S103 may be omitted. In this case, the ECU 100 executes S150 after S102.

[0133] According to this modification, even when the inverter 20 operates receiving the voltage boosted by the boost chopper circuit 110, the battery current value can be accurately estimated.

[0134] [Other Modifications] Vehicle 1 may separately include a peak detection circuit (not shown) for detecting each peak value from ECU100. The peak detection circuit provides the peak value it detects to ECU100.

[0135] Vehicle 1 may not include current sensor 30w. In this case, ECU100 estimates current Iw according to the detection values (currents Iu, Iv) of current sensors 30u and 30v. Specifically, ECU100 executes only the first and second processes out of the aforementioned first to third processes (estimates the battery current value only at times ta, tb, tp, and tr).

[0136] Vehicle 1 may be an electric vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a fuel cell electric vehicle (FCEV).

[0137] Vehicle 1 may not include inverter 70 and motor 75. In this case, Vehicle 1 is a two-wheel drive electric vehicle.

Industrial Applicability

[0138] The embodiments disclosed this time should be considered illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0139] 1,1A vehicle, 5 battery, 7 monitoring unit, 7a, 30u, 30v, 30w, 81, 91 current sensor, 20, 70 inverter, 21, 21u, 21v, 21w leg circuit, 22, 22u, 22v, 22w, 112 upper arm circuit, 23, 23u, 23v, 23w, 114 lower arm circuit, 25, 75 motor, 27, 76 sensor unit, 80 high-voltage auxiliary equipment, 90 DC-DC converter, 110 boost chopper circuit.

Claims

1. A power storage device, a first three-phase inverter connected to the power storage device and including a first leg circuit, a second leg circuit, and a third leg circuit, and a first three-phase AC motor connected to the first three-phase inverter, wherein each of the first leg circuit, the second leg circuit, and the third leg circuit includes an upper arm circuit and a lower arm circuit that is turned on and off complementarily to the upper arm circuit, the mode of the first three-phase inverter includes a first mode in which the upper arm circuit of the first leg circuit, the lower arm circuit of the second leg circuit, and the lower arm circuit of the third leg circuit are on, and a second mode in which the lower arm circuit of the first leg circuit, the upper arm circuit of the second leg circuit, and the upper arm circuit of the third leg circuit are on, a first current sensor that detects an alternating current flowing between the first-phase coil of the first three-phase AC motor and the first leg circuit, and a processing device that executes an estimation process for estimating a current value of the power storage device, wherein the estimation process includes a first process of estimating the current value only according to a detection value of the first current sensor when the mode of the first three-phase inverter is the first mode or the second mode. The estimation system.

2. The estimation system according to claim 1, wherein the first process includes a process of estimating the current value according to a peak value of the detection value of the first current sensor.

3. further comprising a second current sensor that detects an alternating current flowing between the second-phase coil of the first three-phase AC motor and the second leg circuit, the mode of the first three-phase inverter includes a third mode in which the lower arm circuit of the first leg circuit, the upper arm circuit of the second leg circuit, and the lower arm circuit of the third leg circuit are on, and a fourth mode in which the upper arm circuit of the first leg circuit, the lower arm circuit of the second leg circuit, and the upper arm circuit of the third leg circuit are on, The estimation system according to claim 2, wherein the estimation process further includes a second process of estimating the current value only according to a detection value of the second current sensor when the mode of the first three-phase inverter is the third mode or the fourth mode.

4. The estimation system according to claim 3, wherein the second process includes a process of estimating the current value according to a peak value of the detection value of the second current sensor after the first current sensor detects the peak value.

5. It further includes at least one electrical device configured to operate by receiving power from the energy storage device. The estimation system according to claim 1, wherein the processing device executes the first process when the at least one electrical device stops and is not energized.

6. The at least one electrical device includes an auxiliary machine configured to operate with the output voltage of the energy storage device, a power converter configured to step down the output voltage, and a second three-phase inverter connected in parallel with the first three-phase inverter to the energy storage device. The estimation system according to claim 5.

7. An energy storage device, a first three-phase inverter connected to the energy storage device and including a first leg circuit, a second leg circuit, and a third leg circuit, and a first three-phase AC motor connected to the first three-phase inverter. Each of the first leg circuit, the second leg circuit, and the third leg circuit includes an upper arm circuit and a lower arm circuit that is turned on and off complementarily to the upper arm circuit. The modes of the first three-phase inverter include a first mode in which the upper arm circuit of the first leg circuit, the lower arm circuit of the second leg circuit, and the lower arm circuit of the third leg circuit are on, and a second mode in which the lower arm circuit of the first leg circuit, the upper arm circuit of the second leg circuit, and the upper arm circuit of the third leg circuit are on. A first current sensor for detecting an alternating current flowing between the first phase coil of the first three-phase AC motor and the first leg circuit, a boost chopper circuit connected between the energy storage device and the first three-phase inverter and including an upper arm circuit and a lower arm circuit, and a processing device that executes an estimation process for estimating the current value of the energy storage device. The estimation process includes a first process of estimating the current value according to the detection value of the first current sensor when the mode of the first three-phase inverter is the first mode or the second mode. The processing device executes the first process when the conduction state of the upper arm circuit of the boost chopper circuit and the non-conduction state of the lower arm circuit of the boost chopper circuit are maintained, and the load of the first three-phase AC motor is constant. Estimation system.

8. It further includes a current detection unit for detecting the current value. The estimation system according to any one of claims 1 to 7, wherein the processing device is further configured to execute a failure diagnosis process for diagnosing the presence or absence of a failure in the current detection unit by comparing the detection value of the first current sensor with the detection value of the current detection unit.

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