Current detection device and motor control device

Abstract

To solve such a problem that an abnormality in a current detection value of one phase cannot be accurately detected while a motor is being driven.SOLUTION: A current detector comprises: a current ratio calculation unit which calculates a current ratio being a ratio of the sum of current detection values of other two phases to a current detection value of one phase in the three-phase AC current output to a three-phase motor while the three-phase motor is being driven; and a current value abnormality determination unit which determines that each current detection value of the three-phase AC current is normal when the current ratio calculated by the current ratio calculation unit is within a prescribed range, and determines that the current detection value of the one phase is abnormal when the current ratio is not included in the prescribed range.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a current detection device and a motor control device. [Background technology]

[0002] The value of the three-phase AC current output to the three-phase motor is detected by a current detection unit composed of a current sensor, etc. In order to accurately control the three-phase motor, it is necessary to accurately detect whether there are any abnormalities in the current detection value detected by the current detection unit.

[0003] Patent Document 1 discloses a control device for a rotating machine that, if the absolute value of any of the currents iu, iw, iv detected by a current sensor is equal to or greater than a specified value α immediately after a vehicle's travel permission switch is switched from off to on, determines that an offset abnormality has occurred, in which the output value of the current sensor deviates by a specified amount, and determines that a gain abnormality has occurred, in which the true value is multiplied by a specified amount, if the absolute value of the sum of the currents iu, iw, iv is greater than a specified value β if it is not equal to or greater than the specified value α. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-013040 A Summary of the Invention [Problem to be solved by the invention]

[0005] The device described in Patent Document 1 cannot accurately detect that the current detection value of one of the three phases is abnormal while the motor is being driven. [Means for solving the problem]

[0006] A current detection device according to the present invention includes a current ratio calculation unit which calculates a current ratio, which is a ratio of a current detection value of one phase of three-phase AC current outputted to the three-phase motor while the three-phase motor is being driven, to a current detection value of the other two phases, and a current value abnormality determination unit which determines that each current detection value of the three-phase AC current is normal if the current ratio calculated by the current ratio calculation unit is within a predetermined range, and determines that the current detection value of the one phase is abnormal if the current ratio is not included in the predetermined range. an angle calculation unit that calculates an electrical angle based on angle information from the three-phase motor; Equipped with The current ratio calculation unit calculates three current ratios with each phase as a reference, and the current value abnormality determination unit determines that the current detection value of the one phase used as the reference is abnormal when any of the three current ratios is not included in the predetermined range within a certain angle range of the electrical angle calculated by the angle calculation unit. . A motor control device according to the present invention includes a current detection unit which detects a three-phase AC current being output to a three-phase motor, a current ratio calculation unit which calculates a current ratio which is the ratio of a current detection value of one phase of the three-phase AC current to a sum of current detection values ​​of the other two phases while the three-phase motor is being driven, and a current value abnormality determination unit which determines that each current detection value of the three-phase AC current detected by the current detection unit is normal if the current ratio calculated by the current ratio calculation unit is within a predetermined range, and determines that the current detection value of one phase is abnormal if the current ratio is not included in the predetermined range. an angle calculation unit that calculates an electrical angle based on angle information from the three-phase motor; Equipped with The current ratio calculation unit calculates three current ratios with each phase as a reference, and the current value abnormality determination unit determines that the current detection value of the one phase used as the reference is abnormal when any of the three current ratios is not included in the predetermined range within a certain angle range of the electrical angle calculated by the angle calculation unit. . Effect of the Invention

[0007] According to the present invention, it is possible to accurately detect that the current detection value of one phase is abnormal while the motor is being driven. [Brief description of the drawings]

[0008] [Figure 1] 1 is a circuit configuration diagram of a motor control device according to a first embodiment. [Diagram 2] FIG. 2 is a circuit configuration diagram of a power conversion circuit. [Diagram 3] 13A and 13B are graphs showing the relationship between the detected current value and the current ratio. [Figure 4] 13 is a flowchart showing the process of a current ratio calculation unit. [Diagram 5] 10 is a flowchart showing a process of a current value abnormality determination unit. [Figure 6]FIG. 11 is a circuit configuration diagram of a motor control device according to a second embodiment. [Figure 7] 10 is a flowchart showing a process of a current correction unit according to the second embodiment. [Figure 8] FIG. 11 is a circuit configuration diagram of a motor control device according to a third embodiment. [Figure 9] 13 is a flowchart showing a process of a current ratio calculation unit according to the third embodiment. [Figure 10] 13 is a flowchart showing a process of a current correction unit according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] In the following description, the processing shown in the flowchart may be described, but this processing is performed by executing a program, and the program is executed by a processor (e.g., CPU, GPU) to perform the specified processing while appropriately using storage resources (e.g., memory) and / or interface devices (e.g., communication ports), etc., so the subject of the processing may be the processor. Similarly, the subject of the processing performed by executing a program may be a controller, device, system, computer, or node having a processor. The subject of the processing performed by executing a program may be a calculation unit, and may include a dedicated circuit (e.g., FPGA or ASIC) that performs a specific processing.

[0011] A program may be installed in a device such as a computer from a program source. The program source may be, for example, a program distribution server or a computer-readable storage medium. When the program source is a program distribution server, the program distribution server may include a processor and a storage resource for storing a program to be distributed, and the processor of the program distribution server may distribute the program to be distributed to other computers. In the following description, two or more programs may be realized as one program, and one program may be realized as two or more programs.

[0012] [First embodiment] FIG. 1 is a circuit configuration diagram of a motor control device 100 according to the first embodiment. The motor control device 100 converts DC power obtained from a DC power supply 200 into AC power to drive a motor 300. The DC power supply 200 is configured with a secondary battery or the like, and supplies DC power. The motor 300 is a three-phase motor having three internal windings. The motor 300 is equipped with an angle sensor 301 such as a resolver that detects the rotation angle of the rotor. The motor 300 is mounted on a vehicle and functions as a drive source for the vehicle during power running and as a generator during regeneration.

[0013] The motor control device 100 includes a power conversion circuit 101, a main control unit 102, a current detection unit 103, an angle calculation unit 104, a current ratio calculation unit 105, and a current value abnormality determination unit 106. The current detection device that detects abnormalities in the current detection value is composed of at least the current ratio calculation unit 105 and the current value abnormality determination unit 106.

[0014] The current detection unit 103 detects the value of the AC current output from the power conversion circuit 101. The current detection unit 103 includes an internal current sensor (not shown) and an A / D conversion circuit that converts analog information output from the current sensor into digital information. Then, the current sensors arranged in each of the UVW phases measure the AC current Iu flowing through the U phase, the AC current Iv flowing through the V phase, and the AC current Iw flowing through the W phase. The analog information output from each current sensor is converted into digital information by the A / D conversion circuit arranged corresponding to each phase, and the current detection values ​​Iu_s, Iv_s, and Iw_s are output to the main control unit 102 and the current ratio calculation unit 105.

[0015] The angle calculation unit 104 receives rotor angle information from an angle sensor 301 arranged in the motor 300 , uses this to calculate an electrical angle θe_s, and outputs it to the main control unit 102 and the current value abnormality determination unit 106 .

[0016] The main control unit 102 communicates with an electronic control unit (not shown) provided outside the motor control device 100, and receives the target torque of the motor 300 from the electronic control unit. In addition, the main control unit 102 receives current detection values ​​Iu_s, Iv_s, and Iw_s from a current detection unit 103 and an electrical angle θe_s from an angle calculation unit 104.

[0017] Then, the main control unit 102 calculates a target current value to be passed through the motor 300 based on the target torque. This target current value is expressed, for example, by a d-axis current target value and a q-axis current target value. Specifically, the main control unit 102 calculates a d-axis current detection value and a q-axis current detection value using the current detection values ​​Iu_s, Iv_s, and Iw_s output from the current detection unit 103 and the electrical angle θe_s output from the angle calculation unit 104. Then, feedback control is performed using the deviation between the d-axis current target value, which is the target current value, and the d-axis current detection value, which is the detection value, and the deviation between the q-axis current target value, which is the target current value, and the q-axis current detection value, which is the detection value, to determine a drive signal to be output to the power conversion circuit 101. Furthermore, the main control unit 102 receives abnormality information from the current value abnormality determination unit 106, and performs control corresponding to the input abnormality information, as will be described in detail later.

[0018] The power conversion circuit 101 includes a three-phase upper and lower arm series circuit composed of switching elements, and performs switching operations of the switching elements based on a drive signal output from a main control unit 102. During power running, the power conversion circuit 101 converts DC power supplied from a DC power supply 200 into three-phase AC power to drive a motor 300. During regeneration, the power conversion circuit 101 converts the three-phase AC power into DC power to charge the DC power supply 200.

[0019] The current ratio calculation unit 105 calculates the current ratios Gu, Gv, Gw shown in the following equations (1), (2), and (3) based on the current detection values ​​Iu_s, Iv_s, and Iw_s input from the current detection unit 103. This calculation is a calculation in which the sum of the current detection values ​​of two phases is divided by the current detection value of the other phase and multiplied by -1.

[0020]

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[0021]

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[0022]

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[0023] In this manner, while driving the three-phase motor 300, the current ratio calculation unit 105 calculates a current ratio which is the ratio of the current detection value of one phase of the three-phase AC current output to the motor 300 to the sum of the current detection values ​​of the other two phases. Then, the current ratio calculation unit 105 outputs the calculated current ratios Gu, Gv, Gw to the current value abnormality determination unit 106.

[0024] The current value abnormality determination unit 106 receives the current ratios Gu, Gv, and Gw from the current ratio calculation unit 105 and the electrical angle θe_s from the angle calculation unit 104. The current value abnormality determination unit 106 monitors the current ratios Gu, Gv, and Gw, and determines that the current ratios are normal if the three current ratios Gu, Gv, and Gw are considered to be constant at 1 (within a predetermined range) within a period in which the electrical angle θe_s changes by 180 degrees (a certain angle range of the electrical angle). If only one current ratio has a constant value within a period in which the electrical angle changes by 180 degrees (a certain angle range of the electrical angle) and the other two current ratios do not have constant values ​​(if they are not included in the predetermined range), the current value abnormality determination unit 106 determines that the phase in which the current ratio has become constant is an abnormal phase. That is, if the current ratios calculated by the current ratio calculation unit 105 are within a certain range, the current value abnormality determination unit 106 determines that each current detection value of the three-phase AC current is normal, and if the current ratios are not included in the certain range, the current detection value of one phase is abnormal. The determined abnormality information is output to the main control unit 102.

[0025] When the fault information is input, the main control unit 102 performs control corresponding to the input fault information. Then, the main control unit 102 outputs fault information indicating which phase's current detection value is abnormal to an external electronic control device. When the fault information is input, if the main control unit 102 continues to control the motor 300 despite the current detection values ​​Iu_s, Iv_s, and Iw_s being in an abnormal state, there is a possibility that the motor 300 cannot be accurately controlled. For this reason, the main control unit 102 stops the operation of the power conversion circuit 101. For example, when the current value abnormality determination unit 106 determines that the current detection values ​​Iu_s, Iv_s, and Iw_s are abnormal, the main control unit 102 outputs a drive signal to turn off all switching elements of the power conversion circuit 101 or to turn on all switching elements of the upper arm or lower arm. For example, by turning on all of the switching elements of the upper arm or the lower arm, the windings of the motor 300 are shorted, and even if the function of the power conversion circuit 101 is stopped and the motor 300 is rotated by an external force, the smoothing capacitor is prevented from being charged by the induced voltage of the motor 300.

[0026] FIG. 2 is a circuit configuration diagram of the power conversion circuit 101. The power conversion circuit 101 has UVW-phase upper and lower arm series circuits. The U-phase upper and lower arm series circuit is made up of a U-phase upper arm switching element Tuu and a U-phase upper arm diode Duu, and a U-phase lower arm switching element Tul and a U-phase lower arm diode Dul. The V-phase upper and lower arm series circuit is made up of a V-phase upper arm switching element Tvu and a V-phase upper arm diode Dvu, and a V-phase lower arm switching element Tvl and a V-phase lower arm diode Dvl. The W-phase upper and lower arm series circuit is made up of a W-phase upper arm switching element Twu and a W-phase upper arm diode Dwu, and a W-phase lower arm switching element Twl and a W-phase lower arm diode Dwl.

[0027] The upper arm has a U-phase upper-arm switching element Tuu and a U-phase upper-arm diode Duu, a V-phase upper-arm switching element Tvu and a V-phase upper-arm diode Dvu, and a W-phase upper-arm switching element Twu and a W-phase upper-arm diode Dwu. The lower arm has a U-phase lower-arm switching element Tul and a U-phase lower-arm diode Dul, a V-phase lower-arm switching element Tvl and a V-phase lower-arm diode Dvl, and a W-phase lower-arm switching element Twl and a W-phase lower-arm diode Dwl. These switching elements are hereinafter referred to as switching elements 121. Although an example of a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is shown as the switching element 121, it may be an IGBT (Insulated Gate Bipolar Transistor) or other elements.

[0028] The power conversion circuit 101 is supplied with DC power from the DC power source 200 via the positive electrode B+ and the negative electrode B- of the bus bar. A smoothing capacitor (not shown) is connected between the positive electrode B+ and the negative electrode B- of the bus bar. A driving signal 102U is input from the main control unit 102 to the gate electrode of the switching element 121 of the upper arm. A driving signal 102L is input from the main control unit 102 to the gate electrode of the switching element 121 of the lower arm. AC wiring is led out from each upper and lower arm connection point of the upper and lower arm series circuit of the UVW phases and connected to the winding of the motor 300. When the current value abnormality determination unit 106 determines that the current detection values ​​Iu_s, Iv_s, and Iw_s are abnormal, the main control unit 102 outputs a driving signal to turn off all the switching elements 121 of the power conversion circuit 101 or to turn on all the switching elements 121 of the upper arm or the lower arm.

[0029] 3(A) and 3(B) are graphs showing the relationship between the current detection values ​​Iu_s, Iv_s, Iw_s and the current ratios Gu, Gv, Gw. FIG. 3(A) shows the current detection values ​​Iu_s, Iv_s, Iw_s, and FIG. 3(B) shows the current ratios Gu, Gv, Gw. The horizontal axis is the electrical angle in both cases. An example will be described in which the current detection values ​​Iu_s, Iv_s, Iw_s are normal from 0 electrical angle to 360 electrical angles, and an abnormality occurs in which the amplitude of the U-phase current detection value Iu_s becomes excessive after the electrical angle of 360 electrical degrees.

[0030] As shown in Figure 3(A), from electrical angles of 0 degrees to 360 degrees, the U-phase current detection value Iu_s indicated by the dotted line with small dot spacing, the V-phase current detection value Iv_s indicated by the dotted line with medium dot spacing, and the W-phase current detection value Iw_s indicated by the dotted line with large dot spacing, all have the same amplitude and are shifted in electrical angle by 120 degrees from each other.

[0031] As shown in FIG. 3B, in the range of electrical angles from 0 degrees to 360 degrees, the current ratio Gu based on the U phase indicated by the dotted line with small intervals, the current ratio Gv based on the V phase indicated by the dotted line with medium intervals, and the current ratio Gw based on the W phase indicated by the dotted line with large intervals are all 1. In other words, if the current detection values ​​Iu_s, Iv_s, and Iw_s are normal, the current ratios Gu, Gv, and Gw based on the formulas (1), (2), and (3) are all 1. In other words, if the current detection values ​​Iu_s, Iv_s, and Iw_s are normal, the current value obtained by multiplying the sum of the current detection values ​​of two phases by -1 and the current detection value of the other one phase are in phase and have the same amplitude. Therefore, the calculation results of the current ratios Gu, Gv, and Gw are all 1.

[0032] Suppose that the amplitude of the U-phase current detection value Iu_s becomes excessive at an electrical angle of 360 degrees as shown in Fig. 3(A). As for the current ratios Gu, Gv, and Gw based on equations (1), (2), and (3), as shown in Fig. 3(B), only the current ratio Gu is constant and has a value other than 1, while the current ratios Gv and Gw fluctuate greatly.

[0033] From this, if the calculation results of the current ratios Gu, Gv, Gw are all 1, the current detection values ​​Iu_s, Iv_s, Iw_s are normal, and if only one of the current ratios Gu, Gv, Gw is a constant value other than 1, the current detection values ​​Iu_s, Iv_s, Iw_s of that phase other than 1 can be identified as abnormal. In other words, if the current ratios Gu, Gv, Gw are within a predetermined range, the current detection values ​​Iu_s, Iv_s, Iw_s of the three-phase AC currents are determined to be normal, and if the current ratios Gu, Gv, Gw are not included in the predetermined range, the current detection value of the other one phase can be determined to be abnormal. When one phase is abnormal, the current ratio of the normal phase repeats the same characteristics every 180 degrees of electrical angle, so the abnormality is determined based on whether or not the current ratio exceeds a certain value within a certain range of the electrical angle, for example, during a period when the electrical angle changes by 180 degrees. If the current detection values ​​Iu_s, Iv_s, and Iw_s are abnormal, a malfunction may be present in the current sensor in the current detection unit 103 or in the A / D conversion circuit that performs A / D conversion of analog information output from the current sensor.

[0034] 4 is a flowchart showing the process of the current ratio calculation unit 105. The current ratio calculation unit 105 executes the process of the flowchart shown in FIG. In step S401, the current ratio calculation unit 105 determines whether or not it has received the current detection values ​​Iu_s, Iv_s, and Iw_s sampled by the current detection unit 103. If it has not received them, it repeats the process of step S401 until it has received them. If it has received them, it proceeds to the next step S402.

[0035] In step S402, the current ratio calculation unit 105 calculates the current ratios Gu, Gv, and Gw of the current detection values ​​Iu_s, Iv_s, and Iw_s, respectively, using the above-mentioned equations (1), (2), and (3). Then, in step S403, the calculated current ratios Gu, Gv, Gw are output to the current value abnormality determination unit 106. After the process ends, the process shown in FIG.

[0036] The current detection values ​​Iu_s, Iv_s, and Iw_s of the current detection unit 103 are sampled multiple times during a period in which the electrical angle θe_s of the angle calculation unit 104 changes by 180 degrees. This is to detect, for example, that only the current ratio Gu is constant at a value other than 1, while the current ratios Gv and Gw are fluctuating significantly, as shown in Figures 3(A) and 3(B).

[0037] 5 is a flowchart showing the process of the current value abnormality determination unit 106. The current value abnormality determination unit 106 executes the process of the flowchart shown in FIG. In step S501, the current value abnormality determination unit 106 initializes values. That is, the reference electrical angle θ0 is defined as θe_s, and the abnormality counters k, ku, kv, and kw are set to 0.

[0038] In step S502, current value abnormality determination unit 106 saves the current electrical angle θe_s in θn. Then, in step S503, current value abnormality determination unit 106 obtains the difference between the electrical angle θ0 from angle calculation unit 104 and the electrical angle θn, and determines whether the difference in electrical angle is 180 degrees or more. If the difference is less than 180 degrees, the process proceeds to step S504. Note that in step S503, current value abnormality determination unit 106 obtains the electrical angle from angle calculation unit 104 and determines whether the difference in electrical angle is 180 degrees or more, but instead, the determination may be made based on a command from main control unit 102 indicating that the difference in electrical angle has become 180 degrees or more.

[0039] In step S504, the current value abnormality determination unit 106 determines whether the current ratios Gu_n, Gv_n, Gw_n at the electrical angle θn are 1. Specifically, it determines whether the conditions of the following expressions (4) to (6) are satisfied, where ε is a value that takes into account errors in the calculation of the current ratios.

[0040]

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[0041] If the conditions of the expressions (4) to (6) are not satisfied, the process proceeds to step S505, where the abnormality counter k is incremented by 1. If the conditions of the expressions (4) to (6) are satisfied, the process proceeds to step S506. In step S506, the current value abnormality determination unit 106 determines whether the difference between the current ratio Gu based on the U phase and the previous value is within a certain error ΔG using the following equation (7).

[0042]

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[0043] If the difference is larger than the error ΔG, the abnormality counter ku for the U phase is incremented by 1 in step S507. Thereafter, the process proceeds to step S508, where the current value abnormality determination unit 106 determines whether the difference between the current ratio Gv based on the V phase and the previous value is within a certain error ΔG using the following equation (8).

[0044]

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[0045] If the difference is larger than the error ΔG, 1 is added to the V-phase abnormality counter kv in step S509. Thereafter, the process proceeds to step S510, where current value abnormality determination unit 106 determines whether the difference between the current ratio Gw based on the W phase and the previous value is within a certain error ΔG using the following equation (9).

[0046]

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[0047] If the difference is larger than the error ΔG, 1 is added to the W-phase abnormality counter kw in step S511. The order of steps S506, S508, and S510 is not limited to the order described above, and may be changed.

[0048] Thereafter, the process returns to step S502, and the processes of steps S503 to S511 are performed for the next electrical angle θe_s. If it is determined in step S503 that the difference between the electrical angle θ0 and the electrical angle θn is equal to or greater than 180 degrees, the process proceeds to step S512.

[0049] In step S512, current value abnormality determination unit 106 determines whether the number k of times that the three current ratios Gu, Gv, and Gw could not be considered to be 1 during a period in which the electrical angle changes by 180 degrees is equal to or less than the allowable number k'. If the number is equal to or less than the allowable number k', the process proceeds to step S513, where it is determined to be normal, and abnormality information F is set to 0. If the number is not equal to or less than the allowable number k', the process proceeds to step S514.

[0050] In step S514, if only the value of the U-phase abnormality counter ku is equal to or less than the permissible number k' and the other abnormality counters are greater than the permissible number, the current value abnormality determination unit 106 determines that the U-phase current detection value Iu_s, whose abnormality counter ku is equal to or less than the permissible number, is abnormal. Then, in the next step S515, the abnormality information F, which indicates that the U-phase current detection value Iu_s is abnormal, is set to 1. If the condition in step S514 is not satisfied, the process proceeds to step S516.

[0051] In step S516, if only the value of the V-phase abnormality counter kv is equal to or less than the permissible number k' and the other abnormality counters are greater than the permissible number, the current value abnormality determination unit 106 determines that the V-phase current detection value Iv_s, for which the abnormality counter kv is equal to or less than the permissible number, is abnormal. Then, in the next step S517, the abnormality information F, which indicates that the V-phase current detection value Iv_s is abnormal, is set to 2. If the condition in step S516 is not satisfied, the process proceeds to step S518.

[0052] In step S518, if only the value of the W-phase abnormality counter kw is equal to or less than the allowable number k' and the other abnormality counters are greater than the allowable number, the current value abnormality determination unit 106 determines that the W-phase current detection value Iw_s, whose abnormality counter kw is equal to or less than the allowable number, is abnormal. Then, in the next step S519, the abnormality information F, which indicates that the W-phase current detection value Iw_s is abnormal, is set to 3. If the condition in step S518 is not satisfied, the process proceeds to step S520.

[0053] In step S520, the current value abnormality determination unit 106 determines that the current detection values ​​Iu_s, Iv_s, and Iw_s of the phases are abnormal other than an abnormality in only one phase, and sets the abnormality information F indicating this to 4. An abnormality other than an abnormality in only one phase is, for example, an abnormality in two phases, three phases, or other phases.

[0054] After the processes of steps S513, S515, S517, S519, and S520, the process proceeds to step S521. In step S521, current value abnormality determination unit outputs abnormality information F to main control unit .

[0055] As already described, when the current value abnormality determination unit 106 determines that the current detection values ​​Iu_s, Iv_s, and Iw_s are abnormal, that is, when F=1, F=2, F=3, or F=4, the main control unit 102 that has received the abnormality information F outputs a drive signal to turn off all the switching elements 121 of the power conversion circuit 101, or to turn on all the switching elements 121 of the upper arm or the lower arm. Then, when F=1, the main control unit 102 outputs fault information indicating that the current detection value of the U phase is abnormal, when F=2, the current detection value of the V phase, and when F=3, the current detection value of the W phase to the external electronic control device. When F=4, the main control unit 102 outputs fault information indicating that there is an abnormality in the current detection unit 103, such as that the current detection values ​​of two or more phases are abnormal, to the external electronic control device. When F=0, the current detection unit 103 is normal, so no fault information is output to the external electronic control device, or information indicating normality is output. An annunciation unit (not shown) may be provided to notify an external electronic control device based on the fault information outputted to the external electronic control device, thereby making it possible to grasp an abnormality in the current detection value of each phase.

[0056] Although an example has been described in which an abnormality occurs in which the amplitude of the current detection value of one phase becomes excessively large, an abnormality in which the amplitude of the current detection value of one phase becomes too small can also be detected by similar processing.

[0057] According to this embodiment, it is possible to accurately detect that the current detection value of one phase is abnormal while driving the motor 300. Generally, in a vehicle equipped with the motor 300, it is not possible to accurately detect that the current detection value is abnormal while the motor 300 is driving in a normal driving state, but this is possible in this embodiment.

[0058] [Second embodiment] FIG. 6 is a circuit configuration diagram of a motor control device 100' according to the second embodiment. A motor control device 100′ in this embodiment differs from the motor control device 100 shown in the first embodiment in that a current correction unit 107 is provided. The same components as those in the motor control device 100 shown in the first embodiment are given the same reference numerals and their description will be omitted.

[0059] The current correction unit 107 receives the current detection values ​​Iu_s, Iv_s, Iw_s from the current detection unit 103. Furthermore, the current ratios Gu, Gv, Gw are input from the current ratio calculation unit 105. Then, the current correction unit 107 corrects the abnormal current detection values ​​based on abnormality information from the current value abnormality determination unit 106, and outputs the corrected current detection values ​​I'u_s, I'v_s, I'w_s to the main control unit 102. The correction of the current detection values ​​is performed by holding the current ratios Gu, Gv, Gw for a certain period of time and calculating the average value.

[0060] When the abnormality information output from the current value abnormality determination unit 106 is F=1, F=2, or F=3, the main control unit 102 controls the power conversion circuit 101 using the current detection values ​​I'u_s, I'v_s, and I'w_s corrected by the current correction unit 107. When the abnormality information is F=4, similarly to the first embodiment, the main control unit 102 outputs a drive signal to turn off all switching elements 121 in the power conversion circuit 101 or to turn on all switching elements 121 in the upper arm or lower arm.

[0061] FIG. 7 is a flowchart showing the process of the current correction unit 107. In step S702, the current correction unit 107 saves the input current ratios Gu, Gv, Gw as the current ratios Gu_m, Gv_m, Gw_m. Next, in step S703, past current ratios that exceed the maximum sample number N are discarded. Then, in the next step S704, an average value of the current ratios is calculated from the N current ratios of each phase that have been saved. The average value G'u of the current ratios based on the U phase is calculated from the following equation (10), the average value G'v of the current ratios based on the V phase is calculated from the following equation (11), and the average value G'w of the current ratios based on the W phase is calculated from the following equation (12).

[0062]

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[0063] After processing step S704, the process proceeds to step S705. In step S705, the current correction unit 107 judges the abnormality information from the current value abnormality judgment unit 106. That is, it judges whether the condition F=0 is satisfied. If this condition is satisfied, that is, if the current detection value is normal, the process proceeds to step S706. In step S706, the current correction unit 107 does not correct the current detection values ​​Iu_s, Iv_s, and Iw_s input from the current detection unit 103, but sets them as they are as the current detection values ​​I'u_s, I'v_s, and I'w_s.

[0064] If it is determined in step S705 that the condition F=0 is not satisfied, the process proceeds to step S707. In step S707, the current correction unit 107 determines whether F=1. If it is determined that F=1, the process proceeds to step S708.

[0065] In step S708, the current correction unit 107 multiplies the average current ratio G'u based on the U phase by the U phase current detection value Iu_s to obtain the corrected U phase current detection value I'u_s. The other phases do not correct the current detection values ​​Iv_s and Iw_s, but use the current detection values ​​I'v_s and I'w_s. If it is not determined in step S707 that F=1, the process proceeds to step S709.

[0066] In step S709, the current corrector 107 determines whether F = 2. If it is determined that F = 2, the process proceeds to step S710.

[0067] In step S710, the current correction unit 107 multiplies the average current ratio G'v based on the V phase by the V phase current detection value Iv_s to obtain the corrected V phase current detection value I'v_s. The other phases use the current detection values ​​Iu_s and Iw_s as the current detection values ​​I'u_s and I'w_s without correcting them. If it is not determined in step S709 that F=2, the process proceeds to step S711.

[0068] In step S711, the current corrector 107 determines whether F = 3. If it is determined that F = 3, the process proceeds to step S712.

[0069] In step S712, the current correction unit 107 multiplies the average value G'w of the current ratio with respect to the W phase as a reference by the W phase current detection value Iw_s to obtain the corrected W phase current detection value I'w_s. For the other phases, the current detection values ​​Iu_s and Iv_s are not corrected, and are set to the current detection values ​​I'u_s and I'vs. If it is not determined in step S711 that F=3, the process proceeds to step S713.

[0070] In step S713, since this is an abnormality that cannot be corrected (F≠0≠1≠2≠3), the current correction unit 107 does not correct the current detection values ​​Iu_s, Iv_s, and Iw_s input from the current detection unit 103, and instead sets them as current detection values ​​I'u_s, I'v_s, and I'w_s.

[0071] Then, after steps S706, S708, S710, S712, and S713, the process proceeds to step S714, where the current corrector 107 outputs the current detection values ​​I'u_s, I'v_s, and I'w_s to the main controller .

[0072] According to this embodiment, it is possible to accurately detect that the current detection value of one phase is abnormal while the motor 300 is being driven, and further, the abnormal current detection value of one phase can be corrected while the motor 300 is being driven, so that a vehicle equipped with the motor 300 can continue to run. Note that in this embodiment, in step S704, the average values ​​G'u, G'v, and G'w of the current ratios based on the U phase, V phase, and W phase, respectively, are calculated, but it is also possible to skip the process of step S704 and calculate only the values ​​of the average values ​​G'u, G'v, and G'w to be used in the respective processes in the subsequent steps S708, S710, and S712.

[0073] [Third embodiment] FIG. 8 is a circuit configuration diagram of a motor control device 100'' according to the third embodiment. The motor control device 100" in this embodiment differs from the motor control device 100' shown in the second embodiment in the processing of the current ratio calculation unit 105. The same parts as the motor control devices 100 and 100' shown in the first and second embodiments are given the same reference numerals and their description will be omitted.

[0074] In the first and second embodiments, the processing of the current ratio calculation unit 105 is synchronized with the sampling timing of the current detection unit 103. Therefore, when the sampling timing interval is short, the number of calculations of the current ratio calculation unit 105 increases, which places a burden on the current ratio calculation unit 105. Therefore, in the third embodiment, the number of calculations of the current ratio calculation unit 105 is reduced when the motor 300 is running at a low speed.

[0075] The main control unit 102 calculates the rotation speed Nm of the motor 300 based on the electrical angle θe_s input from the angle calculation unit 104. The current ratio calculation unit 105 receives the rotation speed Nm of the motor 300 from the main control unit 102, and if the rotation speed Nm is equal to or higher than the certain rotation speed N'm, calculates the current ratio in synchronization with the sampling timing of the current detection unit 103. On the other hand, if the rotation speed Nm of the motor 300 is lower than the certain rotation speed N'm, the electrical angle θe_s is used to measure the time T2π for a change from 0 degrees to 360 degrees, and the calculation timing Ts is obtained from the number of samples S (≧2) per 180 degrees. The current ratio calculation unit 105 calculates and outputs the current ratio in synchronization with this calculation timing Ts.

[0076] 9 is a flowchart showing the process of the current ratio calculation unit 105 according to this embodiment. The current ratio calculation unit 105 executes the process shown in the flowchart in FIG.

[0077] In step S901, the current ratio calculation unit 105 determines whether or not it has received the current detection values ​​Iu_s, Iv_s, and Iw_s sampled by the current detection unit 103. If it has not received them, it repeats the process of step S901 until it has received them. If it has received them, it proceeds to the next step S902.

[0078] In step S902, the current ratio calculation unit 105 determines whether the rotation speed Nm of the motor 300 is equal to or higher than a certain rotation speed N'm. If the rotation speed is high, in step S903, the current ratio calculation unit 105 calculates the current ratios Gu, Gv, and Gw of the current detection values ​​Iu_s, Iv_s, and Iw_s using the already-described formulas (1), (2), and (3), respectively. Then, in step S904, the calculated current ratios Gu, Gv, and Gw are output to the current value abnormality determination unit 106 and the current correction unit 107. After the process ends, the process shown in FIG. 7 is repeated.

[0079] If it is determined in step S902 that the rotation speed Nm of the motor 300 is lower than the certain rotation speed N'm, the process proceeds to step S905.

[0080] In step S905, the current ratio calculation unit 105 measures the time T2π that changes from 0 degrees to 360 degrees using the electrical angle θe_s. Then, in the next step S906, the time T2π is divided by 2S to obtain the calculation timing Ts, where S (≧2) is the number of samples per 180 degrees of electrical angle. In the next step S907, the counter ts is initialized. Then, in the next step S908, the counter ts is counted up. In step S909, it is determined whether the counter ts has exceeded the calculation timing Ts, and if it has not exceeded, the process returns to step S908, and if it has exceeded, the current ratios Gu, Gv, and Gw are calculated by the process from step S903 onwards and output to the current value abnormality determination unit 106 and the current correction unit 107. The process of the current value abnormality determination unit 106 is the same as that described with reference to FIG. 5.

[0081] FIG. 10 is a flowchart showing the process of the current correction unit 107 according to the present embodiment. In step S701, the current correction unit 107 determines whether the current ratios Gu, Gv, and Gw input from the current ratio calculation unit 105 have been updated from the values ​​at the time of the previous input. If they have been updated, the process proceeds to step S702. The process from step S702 onwards is the same as that described with reference to FIG.

[0082] After the process of step S704, or in step S701, if the current ratios Gu, Gv, and Gw have not been updated from the values ​​at the time of the previous input, the process proceeds to step S705. If the current ratios Gu, Gv, and Gw have not been updated, the current detection values ​​are corrected based on the average value of the current ratios calculated previously, as shown in the following steps. The process from step S705 onwards is similar to that described with reference to FIG. 7, and therefore the description thereof will be omitted.

[0083] In the present embodiment, the current ratio calculation unit 105 obtains the calculation timing Ts according to the motor rotation speed Nm, and calculates and outputs the current ratio in synchronization with the calculation timing Ts. As another example, the sampling timing of the current detection values ​​Iu_s, Iv_s, and Iw_s in the current detection unit 103 may be determined according to the motor rotation speed Nm. That is, the current detection unit 103 refers to the rotation speed Nm of the motor 300, and when the rotation speed Nm of the motor 300 is low, the sampling timing is set to be sparse, and when the rotation speed Nm of the motor 300 is high, the sampling timing is set to be dense. In this case, the processing of the current ratio calculation unit 105 is performed as described with reference to the flowchart of FIG. 4. That is, the current ratio calculation unit 105 executes the processing of the flowchart shown in FIG. 4 according to the motor rotation speed Nm, so that the load of the current ratio calculation unit 105, which increases the number of calculations, can be reduced.

[0084] According to this embodiment, it is possible to accurately detect that the current detection value of one phase is abnormal while the motor 300 is being driven, and further, it is possible to reduce the computation load for detecting that the current detection value is abnormal.

[0085] In each of the embodiments described above, the circuit configuration diagram of the motor control device 100, 100', 100" has been explained as being divided into multiple blocks such as the main control unit 102, angle calculation unit 104, current ratio calculation unit 105, current value abnormality determination unit 106, and current correction unit 107 for ease of understanding. However, this division into blocks is just one example, and the configuration may also be implemented by executing a program describing all or some of the functions of the multiple blocks by a processor (e.g., a CPU or GPU).

[0086] According to the embodiment described above, the following advantageous effects can be obtained. (1) The current detection device includes a current ratio calculation unit 105 that calculates a current ratio, which is the ratio of the current detection value of one phase of the three-phase AC current output to the three-phase motor 300 while the three-phase motor 300 is being driven, to the sum of the current detection values ​​of the other two phases, and a current value abnormality determination unit 106 that determines that each current detection value of the three-phase AC current is normal if the current ratio calculated by the current ratio calculation unit 105 is within a predetermined range, and determines that the current detection value of one phase is abnormal if the current ratio is not within the predetermined range. This makes it possible to accurately detect that the current detection value of one phase is abnormal while the motor is being driven.

[0087] (2) The motor control devices 100, 100', 100" each include a current detection unit 103 that detects three-phase AC current being output to the three-phase motor 300, a current ratio calculation unit 105 that calculates a current ratio, which is the ratio of the current detection value of one phase of the three-phase AC current to the sum of the current detection values ​​of the other two phases, while the three-phase motor 300 is being driven, and a current value abnormality determination unit 106 that determines that each current detection value of the three-phase AC current detected by the current detection unit 103 is normal if the current ratio calculated by the current ratio calculation unit 105 is within a predetermined range, and determines that the current detection value of one phase is abnormal if the current ratio is not within the predetermined range. This makes it possible to accurately detect that the current detection value of one phase is abnormal while the motor is being driven.

[0088] The present invention is not limited to the above-described embodiment, and other forms that are conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention as long as they do not impair the characteristics of the present invention. In addition, the above-described embodiments and modified examples may be combined. [Explanation of symbols]

[0089] 100, 100', 100"...motor control device, 101...power conversion circuit, 102...main control unit, 103...current detection unit, 104...angle calculation unit, 105...current ratio calculation unit, 106...current value abnormality determination unit, 107...current correction unit, 200...DC power supply, 300...motor, 301...angle sensor, Tuu...U-phase upper arm switching element, Duu...U-phase upper arm diode, Tul... ·U-phase lower-arm switching element, Dul···U-phase lower-arm diode, Tvu···V-phase upper-arm switching element, Dvu···V-phase upper-arm diode, Tvl···V-phase lower-arm switching element, Dvl···V-phase lower-arm diode, Twu···W-phase upper-arm switching element, Dwu···W-phase upper-arm diode, Twl···W-phase lower-arm switching element, Dwl···W-phase lower-arm diode.

Claims

1. a current ratio calculation unit that calculates a current ratio, which is a ratio of a current detection value of one phase of three-phase AC current outputted to the three-phase motor to a sum of current detection values ​​of the other two phases, while the three-phase motor is being driven; a current value abnormality determination unit that determines that each current detection value of the three-phase AC current is normal when the current ratio calculated by the current ratio calculation unit is within a predetermined range, and that the current detection value of one phase is abnormal when the current ratio is not included in the predetermined range; an angle calculation unit that calculates an electrical angle based on angle information from the three-phase motor, The current ratio calculation unit calculates three current ratios based on each phase, The current value abnormality determination unit determines that the current detection value of the one phase used as the reference is abnormal when any of the three current ratios is not included in the specified range within a certain angle range of the electrical angle calculated by the angle calculation unit.

2. 2. The current detection device according to claim 1, A current detection device, wherein the fixed angular range of the electrical angle is 180 degrees.

3. 3. The current detection device according to claim 1, a current correction unit that, when the current value abnormality determination unit determines that the current detection value of any one of the phases of the three-phase AC current is abnormal, multiplies the current detection value of that phase by an average value of the current ratio of that phase within the certain angle range and outputs the result.

4. a current detection unit that detects a three-phase AC current output to the three-phase motor; a current ratio calculation unit that calculates a current ratio, which is a ratio of a current detection value of one phase of the three-phase AC current to a sum of current detection values ​​of the other two phases, while the three-phase motor is being driven; a current value abnormality determination unit that determines that each current detection value of the three-phase AC current detected by the current detection unit is normal when the current ratio calculated by the current ratio calculation unit is within a predetermined range, and that the current detection value of one phase is abnormal when the current ratio is not included in the predetermined range; an angle calculation unit that calculates an electrical angle based on angle information from the three-phase motor, The current ratio calculation unit calculates three current ratios based on each phase, The motor control device, wherein the current value abnormality determination unit determines that the current detection value of the one phase used as the reference is abnormal when any of the three current ratios is not included in the specified range within a certain angle range of the electrical angle calculated by the angle calculation unit.

5. 5. The motor control device according to claim 4, A motor control device in which the fixed angular range of the electrical angle is 180 degrees.

6. 5. The motor control device according to claim 4, a current correction unit that, when the current value abnormality determination unit determines that the current detection value of one of the phases of the three-phase AC current is abnormal, multiplies the current detection value of that phase by an average value of the current ratio of that phase within the certain angle range and outputs the result.

7. 7. The motor control device according to claim 4, a power conversion circuit including a three-phase upper and lower arm series circuit configured with switching elements, converting supplied DC power into AC power by switching operations of the switching elements, and outputting the three-phase AC current to the three-phase motor; a main control unit that drives and controls the switching elements of the power conversion circuit, The main control unit is a motor control device that outputs a drive signal to turn off all of the switching elements of the power conversion circuit or to turn on all of the switching elements of the upper arm or the lower arm when the current value abnormality determination unit determines that the current detection value is abnormal.

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