JP4727405B2 - Electric motor control device - Google Patents

Description

  The present invention relates to a control device for an electric motor.

Conventionally, for example, with respect to an inverter that controls a motor for driving a vehicle by pulse width modulation (PWM), a motor detected by a current sensor at a timing when a PWM signal that is a control signal for controlling the operation of the inverter is not output. A control device is known in which the value of each phase current is set as an offset, and the detected value of the current sensor is corrected by this offset (see, for example, Patent Document 1).
Further, conventionally, for example, an integrated value obtained by integrating each phase current of the motor detected by the current sensor over one cycle, or positive / negative for one cycle of each phase current of the motor detected by the current sensor. There is known a control device that calculates an offset from a time ratio and corrects a detection value of a current sensor based on the offset (see, for example, Patent Document 2).
JP 2000-23490 A JP-A-5-252785

By the way, in the control device according to the above prior art, simply by setting the offset of the current sensor only at the timing when the PWM signal is not output, the offset cannot be detected in the period of continuing the operation of the motor, For example, when the offset of the current sensor fluctuates according to a temperature change in a state where energization of the electric motor is continued, there arises a problem that it is difficult to appropriately correct the detection value of the current sensor.
In addition, when the phase currents of the motor are integrated over one cycle or when the positive / negative time ratio over one cycle of each phase current detected by the current sensor is calculated, the calculation load increases. As a result, there is a problem that the calculation accuracy of the offset is lowered due to current ripples and harmonic components of the currents of the respective phases.
In addition, prior to the execution of the process for correcting the offset of the current sensor, it is desired to quickly and accurately determine whether or not the current sensor is normal.
The present invention has been made in view of the above circumstances, and it is possible to quickly and accurately determine whether or not a current sensor for detecting a current supplied to an electric motor is normal regardless of an operating state of the electric motor. It is an object of the present invention to provide an electric motor control device that can appropriately correct an offset error that occurs in the detected value and appropriately control the electric motor.

In order to solve the above-described problems and achieve the object, the motor control device according to the first aspect of the present invention is applied to a multi-phase motor by a pulse width modulation signal (for example, a PWM signal in the embodiment). Of the inverter (for example, the PWM inverter 14A in the embodiment) and current detection means (for example, the DC link current IDC in the embodiment) of the inverter (for example, the DC link current IDC in the embodiment) DC-side current sensor 14b) in the embodiment, and the phase current of the motor based on the DC-side current detected by the current detection means (for example, each phase current Iu, Iv, Iw in the embodiment) Phase current estimation means (for example, the phase current estimation unit 26 in the embodiment) for estimating the switching current of the inverter based on the phase current estimated by the phase current estimation means A control device (for example, the control unit 15 in the embodiment) that controls switching to control the on / off state, and when the switching control is performed by the control device, Zero determination means (for example, the current detection availability determination unit 30 in the embodiment) for determining whether or not the timing is a timing within a zero interval, which is a time interval in which the direct current is zero, and the zero First abnormality determination means for determining an abnormal state when the current detection means detects the DC-side current larger than a predetermined value at a timing determined by the determination means to be within the zero interval. (e.g., the abnormality determination unit 33 in the embodiment) and the appropriate timing, nonzero Ward the DC side current is larger time interval than zero It is determined by the non-zero determination means (for example, the current detection availability determination unit 30 in the embodiment) which determines whether or not the timing is within the non-zero interval, and the non-zero determination means by the non-zero determination means. When the DC current that becomes zero is detected by the current detection means at a predetermined timing, and the absolute value of the command value of the phase current corresponding to the non-zero interval is larger than a predetermined lower limit value, an abnormal state A second abnormality determination means (for example, the abnormality determination unit 33 in the embodiment) that determines that the motor is in the state, and whether the appropriate timing is the timing of the driving state or the power generation state of the motor. State determination means (for example, the drive-power generation determination unit 29 in the embodiment), and the current detection means at a timing when the state determination means determines that the motor is in a drive state. When the generated current is detected as the DC side current by the above, or the driving current is detected as the DC side current by the current detecting means at the timing when the state determining means determines that the electric motor is in the power generation state A third abnormality determining means (for example, the abnormality determining unit 33 in the embodiment) for determining that the state is abnormal, the first abnormality determining means, the second abnormality determining means, and the third abnormality determining means. When the current detection unit is determined to be in an abnormal state when it is determined that the current detection unit is in an abnormal state, the determination unit (for example, the abnormality determination unit 33 in the embodiment) and the determination After the current detecting means is determined not to be in an abnormal state by the means, the current detecting means is sent to the current detecting means at a timing determined by the zero determining means to be within the zero interval. When the DC side current below the predetermined value is detected, the DC side current is set as an offset value for the detection result of the current detection unit, and the detection result of the current detection unit is corrected according to the offset value. DC side current correction means (for example, the offset correction unit 25 in the embodiment) is provided.

  According to the motor control device having the above-described configuration, for example, when a DC-side current larger than a predetermined value is detected at a timing when the DC-side current is determined to be zero according to various command values in switching control, etc. Since the current detection means is determined to be in an abnormal state, for example, the current detection means simply determines whether or not the direct current detected by the current detection means has exceeded a predetermined determination threshold value. Compared with the case where it is determined whether or not it is in an abnormal state, it is possible to determine whether or not the current detection means is in an abnormal state quickly and accurately.

  According to the motor control device having the above-described configuration, for example, a DC side current that becomes zero is detected at a timing when the DC side current is determined to be a value other than zero according to various command values in switching control. In this case, since the current detection means is determined to be in an abnormal state, whether or not the current detection means is in an abnormal state quickly and accurately even when the DC current is not detected by the current detection means. It can be determined whether or not.

  According to the motor control apparatus configured as described above, for example, when it is determined that the motor is in a driving state or a power generation state in accordance with various command values in switching control, a DC-side current that does not correspond to the state of the motor is detected. In this case, since the current detection unit is determined to be in an abnormal state, for example, depending on the determination result of whether or not the direct current detected by the current detection unit has exceeded a predetermined determination threshold. Therefore, it is possible to determine whether the current detection unit is in an abnormal state quickly and accurately compared to the case where it is determined whether the current detection unit is in an abnormal state.

  According to the motor control device having the above-described configuration, for example, a DC-side current of a predetermined value or less is detected at a timing when the DC-side current is determined to be zero according to various command values in switching control. In this case, it is determined that an offset error has occurred in the detection result of the current detection means, and the direct current side current is set as an offset value, so that the reliability of the detection result of the current detection means can be quickly and appropriately determined. Can be improved.

According to the motor control device of the present invention described in claim 1, for example, a DC side current larger than a predetermined value is detected at a timing when the DC side current is determined to be zero according to various command values in switching control. If it is detected, it is determined that the current detection means is in an abnormal state. For example, the determination result whether or not the direct current detected by the current detection means has exceeded a predetermined determination threshold is simply used. Accordingly, it is possible to determine whether or not the current detection unit is in an abnormal state more quickly and accurately than when determining whether or not the current detection unit is in an abnormal state.
Furthermore , even when the DC current is not detected by the current detection means, it is possible to quickly and accurately determine whether or not the current detection means is in an abnormal state.

Furthermore, fast and can be accurately current detection means to determine whether an abnormal state, it is possible to improve the reliability of the detection result of the current detecting means.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an electric motor control device of the present invention will be described with reference to the accompanying drawings.
An electric motor control device 10 (hereinafter simply referred to as a motor control device 10) according to this embodiment is, for example, a brushless DC motor 12 (hereinafter simply referred to as a motor 12) mounted as a drive source together with an internal combustion engine 11 in a hybrid vehicle. The motor 12 is directly connected in series with the internal combustion engine 11 and has a rotor (not shown) having a permanent magnet used for the field and a rotating magnetic field for rotating the rotor. And a stator (not shown) to be generated.
For example, as shown in FIG. 1, the motor control device 10 includes a power drive unit (PDU) 14 that uses a battery 13 as a DC power source and a control unit 15.

In this motor control device 10, the drive and regenerative operation of a motor 12 having a plurality of phases (for example, U-phase, V-phase, and W-phase) is received by a control command output from the control unit 15 and is a power drive unit (PDU). 14.
For example, as shown in FIG. 2, the PDU 14 includes a pulse width modulation (including a bridge circuit 14 a formed by bridge connection using a plurality of transistor switching elements (for example, IGBT: Insulated Gate Bipolar Mode Transistor)) and a smoothing capacitor C ( A PWM inverter 14 </ b> A based on PWM) is connected to a high-voltage battery 13 that exchanges electric energy with the motor 12.

The PWM inverter 14A provided in the PDU 14 includes a high-side, low-side U-phase transistor UH, UL and a high-side, low-side V-phase transistors VH, VL and a high-side, low-side W-phase transistor WH that are paired for each phase. , WL and a smoothing capacitor C, and the transistors UH, VH, WH are connected to the positive terminal of the battery 13 to form a high side arm. UL, VL, and WL are connected to the negative terminal of the battery 13 to form a low-side arm, and the transistors UH, UL and VH, VL, WH, and WL that are paired for each phase are in series with the battery 13. Between the collector and emitter of each transistor UH, UL, VH, VL, WH, WL from the emitter. As a forward direction toward the collector, each diode DUH, DUL, DVH, DVL, DWH, DWL is connected.
Between the bridge circuit 14a and the negative terminal of the battery 13, a direct current sensor 14b that detects a direct current (DC link current) IDC of the PWM inverter 14A is provided.

  The PDU 14 sets a pair for each phase in the PWM inverter 14A based on a gate signal (that is, a PWM (pulse width modulation) signal) that is a switching command input from the control unit 15 when the motor 12 is driven, for example. The DC power supplied from the battery 13 is converted into three-phase AC power by switching the ON / OFF (cut-off) state of each of the transistors UH, UL and VH, VL and WH, WL. By sequentially commutating energization to the stator windings of the motor 12, AC U-phase current Iu, V-phase current Iv, and W-phase current Iw are passed through the stator windings of each phase.

The gate signal input from the control unit 15 to the PDU 14 is, for example, according to the combination of the on / off states of the transistors UH, UL and VH, VL, and WH, WL paired for each phase, for example, Table 1 and FIG. As shown in 3 (a) to (h), a PWM (pulse width modulation) signal corresponding to each of the eight switching states S1 to S8 is obtained.
Then, phase currents Iu, Iv, Iw are intermittently generated on the DC side of the PWM inverter 14A in accordance with the switching states S1 to S8, and the DC side current (DC link current) detected by the DC side current sensor 14b. ) IDC is one of the phase currents Iu, Iv, Iw, or one of the phase currents Iu, Iv, Iw inverted, or zero.

For example, at each time t1 to time t8 in one period (carrier period fc) of a carrier signal composed of a single triangular wave with respect to each phase output voltage * Vu, * Vv, * Vw shown in FIG. In the period from time t1 to time t2 that is the start timing and from time t7 to time t8 that is the end timing of the carrier cycle fc, the high side arm of the bridge circuit 14a is in the on state and the low side arm is in the off state. In the first switching state S1, the DC link current IDC becomes zero.
In the period from time t2 to time t3 and in the period from time t6 to time t7, which is the second switching state S2 in which the high-side U-phase and V-phase transistors UH and VH and the low-side W-phase transistor WL are turned on, The DC link current IDC is a current (−Iw) obtained by inverting the sign of the W-phase current Iw.
In the period from time t3 to time t4 and in the period from time t5 to time t6, which is the seventh switching state S7 in which the high-side U-phase transistor UH and the low-side V-phase and W-phase transistors UL and WL are turned on. The DC link current IDC becomes the U-phase current Iu.
The DC link current IDC is zero during the period from time t4 to time t5, which is the eighth switching state S8 in which the high side arm is off and the low side arm is on.

  The control unit 15 performs current feedback control on the dq coordinates forming the rotation orthogonal coordinates and detects an abnormality (for example, failure) of the DC-side current sensor 14b. For example, in the current feedback control, the driver The Id command * Id and the Iq command * Iq are calculated from the torque command Tr set according to the accelerator opening degree related to the accelerator operation, and each phase output voltage * Vu is calculated based on the Id command * Id and the Iq command * Iq. , * Vv, * Vw are calculated, a PWM signal as a gate signal is input to the PDU 14 according to each phase output voltage * Vu, * Vv, * Vw, and each phase actually supplied from the PDU 14 to the motor 12 Each phase estimation current Ius, Ivs, Iws, which is each estimated value for the currents Iu, Iv, Iw, is estimated from the DC link current IDC, and each phase estimation current Ius, Iv is estimated. Performs a d-axis current Ids and the q-axis current Iqs obtained by converting on dq coordinates Iws, the control so that each deviation between the Id command * Id and the Iq command * Iq is zero.

The control unit 15 includes, for example, a current command calculation unit 21, a current control unit 22, a first dq-3 phase conversion unit 23, a PWM signal generation unit 24, an offset correction unit 25, and a phase current estimation unit 26. A three-phase-dq conversion unit 27, a rotation speed calculation unit 28, a drive-power generation determination unit 29, a current detection availability determination unit 30, a second dq-3 phase conversion unit 31, a current magnitude determination unit 32, An abnormality determination unit 33 is provided.
The control unit 15 detects a DC side current (DC link current) IDC detected by the DC side current sensor 14b and a voltage sensor 13a that detects a terminal voltage (power supply voltage) VB of the battery 13. Value, a rotation angle of the rotor of the motor 12 (that is, a rotation angle of the magnetic pole of the rotor from a predetermined reference rotation position) θ, a detection signal output from the rotation sensor 12a, and an external control device (not shown) ) Is output.

  The current command calculation unit 21 is required according to, for example, a torque command Tr (for example, a depression amount of an accelerator pedal by a driver, a rotational speed ω of the motor 12, etc.) input from an external control device (not shown). Command values for causing the motor 12 to generate torque) and the rotational speed ω of the motor 12 input from the rotational speed calculator 28, the phase currents Iu, Iv, Iw supplied from the PDU 14 to the motor 12 are A current command for designating is calculated, and this current command is output to the current control unit 22 as an Id command * Id and a * Iq command * Iq on rotating rectangular coordinates.

  The dq coordinates forming the rotation orthogonal coordinates are, for example, a field magnetic flux direction by a permanent magnet of a rotor as a d axis (field axis), and a direction orthogonal to the d axis as a q axis (torque axis). It rotates in synchronization with the rotational phase of the 12 rotors. As a result, the Id command * Id and the Iq command * Iq, which are DC signals, are given as current commands for the AC signal supplied from the PDU 14 to each phase of the motor 12.

The current control unit 22 calculates a deviation ΔId between the Id command * Id and the d-axis current Ids and a deviation ΔIq between the Iq command * Iq and the q-axis current Iqs. For example, a motor input from the rotation speed calculation unit 28 By a PI (proportional integration) operation corresponding to the rotational speed ω, the deviation ΔId is controlled and amplified to calculate the d-axis voltage command value * Vd, and the deviation ΔIq is controlled and amplified to calculate the q-axis voltage command value * Vq.
The first dq-3 phase conversion unit 23 uses the rotation angle θ of the rotor input from the rotation sensor 12a to convert the d-axis voltage command value Vd and the q-axis voltage command value Vq on the dq coordinate in a stationary coordinate. It is converted into a U-phase output voltage * Vu, a V-phase output voltage * Vv and a W-phase output voltage * Vw which are voltage command values on a certain three-phase AC coordinate.

  The PWM signal generator 24 switches each of the PWM inverters 14A of the PDU 14 by pulse width modulation based on, for example, sinusoidal output voltages * Vu, * Vv, * Vw and a carrier signal composed of a single triangular wave. A gate signal (that is, a PWM (Pulse Width Modulation) signal) that is a switching command including each pulse for driving the element on / off is generated.

  The offset correction unit 25 is detected by the DC side current sensor 14b based on a DC side current (DC link current) IDC input from the DC side current sensor 14b and an offset correction value input from an abnormality determination unit 33 described later. The DC link current IDC is corrected by subtracting the offset value from the obtained DC link current IDC.

The phase current estimation unit 26 is based on the offset-corrected DC link current IDC input from the offset correction unit 25 and the gate signal input from the PWM signal generation unit 24, and the stator winding of each phase of the motor 12. Each phase estimation current Ius, Ivs, Iws, which is an estimated value for each phase current Iu, Iv, Iw supplied to, is estimated.
That is, the DC link current IDC detected by the DC-side current sensor 14b is obtained by inverting the sign of any one of the phase currents Iu, Iv, Iw, or any one of the phase currents Iu, Iv, Iw. Or, for example, based on Table 1 above, the DC link current IDC detected by the DC-side current sensor 14b in each of the switching states S2 to S7 of the PWM inverter 14A is converted into the estimated currents Ius, Ivs, Iws for each phase. Set as.

  For example, for each of the times t1 to t8 shown in FIG. 4, the DC link current detected by the DC-side current sensor 14b in the period from the time t2 to the time t3 and the period from the time t6 to the time t7 that are in the second switching state S2. IDC is set as a negative W-phase estimated current Iws (that is, -Iws). Further, the DC link current IDC detected by the DC-side current sensor 14b in the period from time t3 to time t4 and in the period from time t5 to time t6, which is the seventh switching state S7, is set as the positive U-phase estimated current Ius. To do.

  The three-phase-dq conversion unit 27 uses the rotation angle θ of the rotor input from the rotation sensor 12a, and each phase estimation current Ius, Ivs, which is a current on a stationary coordinate estimated by the phase current estimation unit 26. Iws is converted into a d-axis current Ids and a q-axis current Iqs on a rotation coordinate based on the rotation phase of the motor 12, that is, a dq coordinate.

  The rotation speed calculation unit 28 calculates the rotation speed ω of the motor 12 based on the detection signal output from the rotation sensor 12a, that is, the rotation angle of the rotor of the motor 12.

Based on the Iq command * Iq output from the current command calculation unit 21, the drive-power generation determination unit 29 determines whether the motor 12 is in a driving state, for example, depending on whether the sign of the Iq command * Iq is positive or negative. It is determined whether there is a power generation state or not, and the determination result is output to the abnormality determination unit 33.
Based on the gate signal input from the PWM signal generation unit 24, the current detection availability determination unit 30 switches the PWM inverter 14A in the switching state (that is, the first switching state S1 in which the high-side arm is on and the low-side arm is off). Alternatively, the PWM inverter 14A is in a zero interval, which is a time interval in which the DC link current IDC becomes zero in accordance with the eighth switching state S8) in which the high-side arm is off and the low-side arm is on, or the PWM inverter In accordance with the switching state of 14A (that is, the second switching state S1 to the seventh switching state S7), it is determined whether the DC link current IDC is a non-zero interval that is a time interval in which the value is greater than zero. The result is output to the abnormality determination unit 33.

The second dq-3 phase converter 31 uses the rotation angle θ of the rotor input from the rotation sensor 12a to convert the Id command * Id and the Iq command * Iq on the dq coordinate to a three-phase alternating current that is a stationary coordinate. It is converted into a U-phase current command * Iu, a V-phase current command * Iv, and a W-phase current command * Iw, which are current command values on the coordinates, and output to the current magnitude determination unit 32.
The current magnitude determination unit 32 determines whether or not each phase current command * Iu, * Iv, * Iw is larger than a predetermined lower limit value, and uses this determination result as each phase current command * Iu, * Iv, * It outputs to the abnormality determination part 33 with Iw.

  In addition to the determination results by the drive-power generation determination unit 29, the current detection enable / disable determination unit 30, and the current magnitude determination unit 32, the abnormality determination unit 33 receives each phase current command * Iu, * input from the current magnitude determination unit 32. Depending on the comparison result of comparing the magnitude and sign of the actual current and the detected value, with Iv and * Iw as the actual current and the DC link current IDC detected by the DC current sensor 14b as the detected value, the DC current sensor It is determined whether 14b is abnormal (for example, failure or the like) or normal. When it is determined that the DC side current sensor 14b is normal, an offset correction value for correcting an offset with respect to the detection value of the DC side current sensor 14b is calculated.

  For example, as shown in FIGS. 5A to 5C, the drive-power generation determination unit 29 determines that the electric motor 12 is in a drive state in an appropriate time interval, and the current magnitude determination unit 32 determines a non-zero interval. For example, as shown in FIG. 5A, each phase current command * Iu, * Iv, * Iw corresponding to is determined to be larger than a predetermined lower limit value near zero. Corresponding to the zero interval, each phase current command * Iu, * Iv, * Iw is stepped between a minimum value below a predetermined lower limit value such as substantially zero and a maximum value greater than the predetermined lower limit value. When the DC link current IDC detected by the DC side current sensor 14b maintains a value larger than a predetermined value, that is, the detected value of the DC link current IDC does not become substantially zero in the zero interval. in case of, Flow side current sensor 14b is determined to be abnormal.

  For example, as shown in FIG. 5 (b), the phase current commands * Iu, * Iv, * Iw correspond to the zero interval and the non-zero interval, and the minimum value below a predetermined lower limit value such as substantially zero. And the DC link current IDC detected by the DC-side current sensor 14b has a value equal to or less than a predetermined value, such as substantially zero, for a state in which the DC link current sensor 14b changes in a step-like manner between When maintaining, that is, when the detected value of the DC link current IDC does not become larger than a predetermined value such as substantially zero in the non-zero interval, it is determined that the DC-side current sensor 14b is abnormal.

  Further, for example, as shown in FIG. 5C, the phase current commands * Iu, * Iv, * Iw corresponding to the zero interval and the non-zero interval are minimum values below a predetermined lower limit value such as substantially zero. And the sign of the DC link current IDC detected by the DC-side current sensor 14b is negative, that is, detected in a step-like manner between the current value and the maximum value greater than the predetermined lower limit value. When the DC link current IDC corresponds to the power generation state of the electric motor 12, or when the absolute value of the DC link current IDC detected by the DC side current sensor 14b maintains a value larger than a predetermined value, that is, DC in the zero section When the detected value of the link current IDC does not become substantially zero, it is determined that the DC side current sensor 14b is abnormal.

  For example, as shown in FIGS. 6A to 6C, the drive-power generation determination unit 29 determines that the electric motor 12 is in a power generation state in an appropriate time interval, and the current magnitude determination unit 32 determines a non-zero interval. When the absolute value of each phase current command * Iu, * Iv, * Iw corresponding to is determined to be larger than a predetermined lower limit value in the vicinity of zero, for example, as shown in FIG. Corresponding to the interval and the non-zero interval, the absolute value of each phase current command * Iu, * Iv, * Iw is a minimum value less than a predetermined lower limit value such as substantially zero, and a maximum value larger than the predetermined lower limit value When the sign of the DC link current IDC detected by the DC side current sensor 14b is positive, that is, the detected DC link current IDC is in the driving state of the motor 12. If yes, yes When the absolute value of the DC link current IDC detected by the DC side current sensor 14b maintains a value larger than a predetermined value, that is, when the detected value of the DC link current IDC does not become substantially zero in the zero interval, It is determined that the DC side current sensor 14b is abnormal.

  For example, as shown in FIG. 6B, the absolute value of each phase current command * Iu, * Iv, * Iw is equal to or less than a predetermined lower limit value such as substantially zero corresponding to the zero interval and the non-zero interval. The absolute value of the DC link current IDC detected by the DC-side current sensor 14b is approximately zero or the like, in a state in which the current value changes in a step-like manner between the minimum value of the DC and the maximum value greater than the predetermined lower limit value. When the value below the predetermined value is maintained, that is, when the absolute value of the detected value of the DC link current IDC does not become larger than the predetermined value such as substantially zero in the non-zero interval, the DC side current sensor 14b is It is determined to be abnormal.

  For example, as shown in FIG. 6C, the absolute value of each phase current command * Iu, * Iv, * Iw is equal to or less than a predetermined lower limit value such as substantially zero corresponding to the zero interval and the non-zero interval. The absolute value of the DC link current IDC detected by the DC-side current sensor 14b is larger than a predetermined value with respect to a state that changes in a step-like manner between the minimum value of the DC and the maximum value that is larger than the predetermined lower limit value. When the value is maintained, that is, when the absolute value of the detected value of the DC link current IDC does not become substantially zero in the zero interval, it is determined that the DC side current sensor 14b is abnormal.

  Further, for example, as shown in FIGS. 7A to 7C, in the appropriate time interval, the current magnitude determination unit 32 determines that the phase current commands * Iu, * Iv, * Iw corresponding to the non-zero interval are, for example, In the state determined to be equal to or less than a predetermined value such as substantially zero, for example, as shown in FIG. 7A, each phase current command * Iu, * Iv, * Iw corresponding to the zero interval and the non-zero interval. However, the DC link current IDC detected by the DC-side current sensor 14b maintains a value larger than the predetermined value with respect to a state where the minimum value and the maximum value less than the predetermined value such as substantially zero change stepwise. In this case, that is, when the detected value of the DC link current IDC does not become substantially zero in the zero interval, it is determined that the DC-side current sensor 14b is abnormal.

  Further, for example, as shown in FIG. 7 (b), each phase current command * Iu, * Iv, * Iw corresponds to a zero interval and a non-zero interval, and the minimum value and maximum value below a predetermined value such as substantially zero. When the sign of the DC link current IDC detected by the DC side current sensor 14b is negative with respect to the state where the value changes stepwise, that is, the detected DC link current IDC corresponds to the power generation state of the motor 12. Or when the absolute value of the DC link current IDC detected by the direct current sensor 14b is larger than a predetermined value, that is, the detected value of the DC link current IDC does not become substantially zero in the zero interval. In this case, it is determined that the DC side current sensor 14b is abnormal.

  For example, as shown in FIG. 7C, each phase current command * Iu, * Iv, * Iw corresponds to a zero interval and a non-zero interval, and the minimum value and the maximum value that are not more than a predetermined value such as substantially zero. When the absolute value of the DC link current IDC detected by the DC side current sensor 14b maintains a value equal to or less than a predetermined value such as substantially zero with respect to a state where the value changes stepwise, the DC side current It is determined that it is impossible to determine whether the sensor 14b is abnormal or normal.

  Further, when the abnormality determination unit 33 determines that the DC-side current sensor 14b is normal, the abnormality determination unit 33 sets the detected value of the DC link current IDC having a value equal to or less than a predetermined value detected in the zero interval as an offset correction value. .

  The motor control device 10 according to the present embodiment has the above-described configuration. Next, the operation of the motor control device 10, in particular, a process for determining whether the DC-side current sensor 14 b is abnormal or normal. Will be described with reference to the accompanying drawings.

First, in step S01 shown in FIG. 6, for example, as shown in FIG. 5C and FIG. 7B, for example, the drive-power generation determination unit 29 determines that the motor 12 is in the drive state. Whether the sign of the DC link current IDC detected by the side current sensor 14b is negative and corresponds to the power generation state of the motor 12, or, for example, as shown in FIG. 29, it is determined whether or not the sign of the DC link current IDC detected by the DC-side current sensor 14b becomes positive and corresponds to the driving state of the motor 12 when the motor 12 is determined to be in the power generation state. .
If this determination is “YES”, the flow proceeds to step S 02, in which the DC-side current sensor 14 b is determined to be abnormal, and the series of processes is terminated.
On the other hand, if this determination is “NO”, the flow proceeds to step S 03.

In step S03, for example, as shown in FIGS. 5A and 6C, the absolute value of the DC link current IDC detected by the DC-side current sensor 14b in the zero interval is a value larger than a predetermined value. It is determined whether or not.
If this determination is “YES”, the flow proceeds to step S 02 described above.
On the other hand, if this determination is “NO”, the flow proceeds to step S 04.

In step S04, for example, as shown in FIGS. 5B and 6B, the absolute value of the DC link current IDC detected by the DC-side current sensor 14b in the non-zero interval is a predetermined value such as substantially zero. It is determined whether or not the absolute value of each phase current command * Iu, * Iv, * Iw corresponding to the non-zero interval is larger than a predetermined lower limit value near zero, for example. To do.
If this determination is “YES”, the flow proceeds to step S 02 described above.
On the other hand, if this determination is “NO”, the flow proceeds to step S 05.

In step S05, it is determined that the DC side current sensor 14b is normal.
Then, the DC link current IDC detected by the DC-side current sensor 14b in the non-zero section is set as an offset correction value, and a series of processes is terminated.

  As described above, according to the motor control device 10 according to the present embodiment, for example, according to the determination result whether or not the DC link current IDC detected by the DC-side current sensor 14b exceeds a predetermined determination threshold. Thus, it is possible to determine whether the DC-side current sensor 14b is in an abnormal state more quickly and accurately than when determining whether the DC-side current sensor 14b is in an abnormal state.

  In the above-described embodiment, the abnormality determination unit 33 determines that the DC-side current sensor 14b is abnormal based on the determination results by the drive-power generation determination unit 29, the current detection possibility determination unit 30, and the current magnitude determination unit 32. However, the present invention is not limited to this. For example, the determination result by the drive-power generation determination unit 29 is not taken into account, that is, the process of step S01 described above is omitted, and the DC side It may be determined whether the current sensor 14b is abnormal or normal.

It is a block diagram of the control apparatus of the electric motor which concerns on embodiment of this invention. It is a block diagram of the PWM inverter of PDU shown in FIG. It is a figure which shows each switching state S1-S8 of the PWM inverter shown in FIG. Changes in the PWM signal and each phase current Iu, Iv, Iw and DC link current IDC in one cycle (carrier cycle fc) of a carrier signal composed of a single triangular wave with respect to each phase output voltage * Vu, * Vv, * Vw It is a graph which shows an example. 5A to 5C show the DC link current IDC detected by the DC-side current sensor 14b with the phase current commands * Iu, * Iv, * Iw inputted from the current magnitude determination unit 32 as actual currents. It is a figure which shows the example of the time change of an actual electric current and a detected value by using as a detected value. 6A to 6C show the DC link current IDC detected by the DC-side current sensor 14b with the phase current commands * Iu, * Iv, * Iw input from the current magnitude determination unit 32 as actual currents. It is a figure which shows the example of the time change of an actual electric current and a detected value by using as a detected value. 7A to 7C show the DC link current IDC detected by the DC current sensor 14b with the phase current commands * Iu, * Iv, * Iw inputted from the current magnitude determination unit 32 as actual currents. It is a figure which shows the example of the time change of an actual electric current and a detected value by using as a detected value. It is a flowchart which shows the process which determines whether a direct current | flow side current sensor is abnormal or it is normal.

Explanation of symbols

10 Motor Control Device 12 Motor 14 PWM Inverter (Inverter)
14b DC side current sensor (current detection means)
15 Control unit (control means)
25 Offset correction unit (DC side current correction means)
26 Phase current estimation unit (phase current estimation means)
29 Drive-power generation determination unit (state determination means)
30 Current detection possibility determination unit (zero determination means, non-zero determination means)
33 Abnormality determination unit ( first abnormality determination means, second abnormality determination means, third abnormality determination means, determination means )

Claims (2)

An inverter that sequentially commutates energization of the motors of the plurality of phases by the pulse width modulation signal, current detection means that detects a DC side current of the inverter, and the DC side current detected by the current detection means based on the DC side current Phase current estimation means for estimating the phase current of the electric motor, and control means for executing switching control for controlling the on / off state of the switching element of the inverter based on the phase current estimated by the phase current estimation means. A control device for an electric motor,
Zero determination means for determining whether or not an appropriate timing is a timing within a zero interval, which is a time interval in which the DC side current becomes zero, when the control means performs the switching control;
A first abnormality that is determined to be an abnormal state when the DC detection current greater than a predetermined value is detected by the current detection means at a timing determined by the zero determination means to be a timing within the zero interval. A determination means ;
Non-zero determination means for determining whether or not the appropriate timing is a timing in a non-zero interval, which is a time interval in which the direct current is greater than zero;
The current detection unit detects the DC side current that is zero at a timing determined by the non-zero determination unit to be a timing within the non-zero interval, and the phase current corresponding to the non-zero interval is detected. A second abnormality determination means for determining that the command value is abnormal when the absolute value of the command value is greater than a predetermined lower limit;
State determination means for determining whether the appropriate timing is a timing of a driving state or a power generation state of the electric motor;
When the current detection unit detects the generated current as the DC side current at the timing when the state determination unit determines that the motor is in the driving state, or the state determination unit is the power generation state of the motor Third abnormality determining means for determining that the current state is in an abnormal state when a drive current is detected as the DC side current by the current detecting means at a timing determined as
When it is determined that at least one of the first abnormality determination unit, the second abnormality determination unit, and the third abnormality determination unit is in an abnormal state, the current detection unit is determined to be in an abnormal state. Determination means to perform,
After the determination means determines that the current detection means is not in an abnormal state, the current detection means determines that the DC side current is less than or equal to the predetermined value at a timing determined by the zero determination means to be within the zero interval. DC-side current correction means for setting the DC-side current when the current is detected as an offset value for the detection result of the current detection means and correcting the detection result of the current detection means according to the offset value; An electric motor control device comprising: The determination means determines that the current detection means is not in an abnormal state when it is determined that the first abnormality determination means, the second abnormality determination means, and the third abnormality determination means are not in an abnormal state. The motor control device according to claim 1, wherein the determination is performed .

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