JP2006050803A - Motor drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive device capable of detecting failure in an inverter even while a motor is rotating at a high speed without need for using any other current sensor than those required for motor control. <P>SOLUTION: If any addition value of actual voltages Vu, Vv, Vw of respective phases of a brushless DC motor is larger than a predetermined threshold value, a motor drive such as an inverter is determined as being failed. With a third harmonic component superimposed on a voltage command value, the motor drive is determined as being failed if the addition value of a voltage is larger than a predetermined value after the third harmonic component is removed from the actual voltages Vu, Vv, Vw. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a drive device for a brushless DC motor used in a motor drive device such as an electric power steering device.

  Conventionally, the abnormality detection of the inverter of the brushless DC motor driving device has been performed whether or not the deviation between the current command value and the actual current is a predetermined value or more, and whether the added value of the three-phase actual current is a predetermined value or more. This is done depending on whether or not (see, for example, Patent Document 1). Here, the actual current is an actual current of all three phases of the brushless DC motor, or a d-axis actual current or a q-axis actual current calculated based on these three-phase actual currents.

The abnormality detection of the inverter performed by the current deviation as described above is performed only when the rotational angular velocity of the motor is smaller than a predetermined value. This is because, when the motor rotates at high speed, the current deviation may increase due to the back electromotive force of the motor even if the inverter is normal. In other words, even if the current deviation becomes large when the motor is rotating at high speed, it is performed only when the rotational angular speed of the motor is smaller than a predetermined value so that it is not determined as abnormal.
JP 2000-184772 A

  By the way, according to abnormality detection by current addition, it is necessary to detect the actual currents of all three phases of the brushless DC motor. However, at least two of the three phases of the brushless DC motor are necessary for controlling the brushless DC motor. That is, in order to detect an abnormality by adding current, it is necessary to provide a current sensor for another one phase that is not necessary for controlling the brushless DC motor. Furthermore, when the motor rotates at high speed, there is a problem that abnormality cannot be detected depending on the current deviation.

  The present invention has been made in view of such circumstances, and without using a current sensor other than the current sensor necessary for motor control, and even if the motor is rotating at high speed, an abnormality such as an inverter is present. An object of the present invention is to provide a motor drive device capable of detection.

  Therefore, the present inventor has intensively studied to solve this problem, and as a result of repeated trial and error, the inventors have come up with the idea of performing abnormality detection by voltage rather than current detection, and have completed the present invention. It was.

(1) 1st this invention That is, the motor drive device of 1st this invention is the motor drive means which applies an alternating voltage to each phase of the said brushless DC motor and the said brushless DC motor, and drives the said brushless DC motor, A motor control unit that outputs a control signal to the motor drive unit to control the brushless DC motor, and further includes an actual voltage detection unit that detects an actual voltage of each phase of the brushless DC motor; Shift actual voltage calculation means for calculating a shift actual voltage of each phase, which is a difference voltage between the detected actual voltage of each phase and a neutral point potential, and an added value of the shift actual voltage of each phase is a predetermined value. And an abnormality determining unit that determines that the motor driving unit is abnormal when it is larger than a first threshold value.

  Here, the motor driving means has an inverter circuit and a PWM output unit. The inverter circuit is composed of a plurality of switching elements. The inverter circuit has an input side connected to a DC power source and an output side connected to a brushless DC motor. The PWM output unit outputs a PWM drive signal for PWM driving each switching element of the inverter circuit. The switching element is, for example, a MOSFET or an IGBT. The neutral point potential is the center potential of the amplitude of the AC voltage applied to each phase of the brushless DC motor. For example, the neutral point potential is the potential at the connection position in the case of a brushless DC motor having a Y connection. Further, the abnormality of the motor driving means is, for example, a short circuit, a ground fault, a power fault, or the like of the switching element of the inverter circuit.

  The control signal is a third superimposed voltage command value obtained by superimposing a third harmonic component of the basic sine wave on a voltage command value composed of a basic sine wave. Further, the control signal is calculated from the shifted actual voltage of each phase. Third-order component removal voltage calculation means for calculating the third-order component removal voltage of each phase from which the third-order harmonic component has been removed is provided, and the abnormality determination means has an added value of the third-order component removal voltage of each phase. You may make it determine with the said motor drive means being abnormal when larger than the said 1st threshold value.

  Here, the line voltage of the brushless DC motor can be increased by superimposing the third harmonic component on the voltage command value composed of the basic sine wave. Further, the third harmonic component superimposed on the voltage command value composed of the fundamental sine wave is composed of a sine wave calculated based on the fundamental sine wave. The third harmonic component used when calculating the third component removal voltage is a sine wave of the third harmonic component of the basic sine wave superimposed on the third superimposed voltage command value. That is, the third-order component removal voltage is a voltage obtained by removing the third-order harmonic component included in the voltage command value from the shifted actual voltage.

  Further, a power supply voltage detecting means for detecting a power supply voltage applied to the motor driving means, and a voltage value of a half of the power supply voltage is calculated, and the voltage value of the half is set to the neutral point. Neutral point potential calculation means for setting a potential may be provided.

(2) Second Invention The motor drive device of the second invention comprises a brushless DC motor, motor drive means for driving the brushless DC motor by applying an AC voltage to each phase of the brushless DC motor, and the brushless Of the actual current flowing through the DC motor, a d / q-axis actual current consisting of a d-axis actual current that is the actual current of the d-axis component and a q-axis actual current that is the actual current of the q-axis component orthogonal to the d-axis is calculated. d / q-axis actual current calculation means; a d-axis current command value that is a current command value of the d-axis component supplied to the brushless DC motor; and a q-axis current command value that is a current command value of the q-axis component. Current command value generating means for generating a d / q axis current command value, and a voltage command value to be applied to the brushless DC motor based on a deviation between the d / q axis current command value and the d / q axis actual current The motor drive A control signal output means for outputting a control signal comprising the voltage command value to the means, further comprising an angular velocity detection means for detecting a rotational angular velocity of the brushless DC motor, and the d / q-axis current command. An estimated voltage value calculating means for calculating an estimated voltage value applied to the brushless DC motor based on the value and the rotational angular velocity, and when a deviation between the estimated voltage value and the voltage command value is larger than a predetermined second threshold value. And an abnormality determining unit that determines that the motor driving unit is abnormal.

  Here, the d-axis direction is the direction of the field flux of the motor, and the q-axis direction is a direction orthogonal to the d-axis direction. The control signal output means may calculate a voltage command value subjected to PI control, for example.

  The control signal output means is a d-axis voltage that is a voltage command value of the d-axis component applied to the brushless DC motor based on a deviation between the d / q-axis current command value and the d / q-axis actual current. D / q-axis voltage command value calculating means for calculating a d / q-axis voltage command value comprising a command value and a q-axis voltage command value that is a voltage command value of the q-axis component; and the d / q-axis voltage command value AC voltage command value output means for calculating an AC voltage command value for each phase of the brushless DC motor and outputting a control signal composed of the AC voltage command value to the motor driving means, and the estimated voltage value is It is at least one of an estimated voltage value of a d-axis component and an estimated voltage value of the q-axis component, and the abnormality determination unit includes a deviation between the estimated voltage value of the d-axis component and the d-axis voltage command value, and the q-axis component estimated voltage value and q It may be determined that there is at least one of the deviation between the voltage command value that is the motor drive unit abnormality is greater than the second threshold value. That is, the abnormality determination of the motor driving means is performed using the voltage value in the d / q axis component. The abnormality determination may be performed based only on the estimated voltage value of the d-axis component and the d-axis voltage command value, or may be performed based only on the estimated voltage value of the q-axis component and the q-axis voltage command value. Furthermore, the abnormality determination may be performed based on the estimated voltage value of the d-axis component, the d-axis voltage command value, the estimated voltage value of the q-axis component, and the q-axis voltage command value. In the case of performing abnormality determination using both the d-axis component and q-axis component voltage values, the deviation between the estimated voltage value of the d-axis component and the d-axis voltage command value, and the estimated voltage of the q-axis component When either one of the deviations between the value and the q-axis voltage command value is larger than the second threshold value, it may be determined that the motor driving means is abnormal.

  The control signal output means is a d-axis voltage that is a voltage command value of the d-axis component applied to the brushless DC motor based on a deviation between the d / q-axis current command value and the d / q-axis actual current. D / q-axis voltage command value calculating means for calculating a d / q-axis voltage command value comprising a command value and a q-axis voltage command value that is a voltage command value of the q-axis component; and the d / q-axis voltage command value AC voltage command value output means for calculating an AC voltage command value for each phase of the brushless DC motor and outputting a control signal composed of the AC voltage command value to the motor driving means, and the estimated voltage value is It is an AC estimated voltage value applied to at least one of the phases of the brushless DC motor, and the abnormality determination unit is configured to output the AC voltage command value corresponding to the phase of the estimated AC voltage value and the estimated AC voltage value. And the deviation is It said motor drive unit is greater than second threshold value may be determined that it is abnormal. That is, the abnormality determination of the motor driving means is performed using the voltage value in the three-phase AC component. The abnormality determination may be performed based on an estimated voltage value of any one of the three-phase components and a voltage command value of the corresponding phase. The abnormality determination may be performed based on the estimated voltage value of any two phases of the three-phase components and the voltage command value of the phase corresponding to them. Furthermore, the abnormality determination may be performed based on the estimated voltage values of all three phases and the voltage command values of the phases corresponding to them. When performing abnormality determination using voltage values of a plurality of phases, it is preferable to determine that the motor driving means is abnormal when any one of the phase deviations is larger than the second threshold value.

(1) Effects of the First Invention According to the first invention, abnormality detection of motor driving means such as an inverter circuit is performed based on the actual voltage of each phase of the brushless DC motor. Specifically, it is determined whether or not the added value of the shift actual voltage of each phase, which is the difference voltage between the actual voltage of each phase of the brushless DC motor and the neutral point potential, is greater than a predetermined first threshold value. . And when the addition value of the shift actual voltage of each phase is larger than a 1st threshold value, it determines with it being abnormal in a motor drive means. Here, the added value of the shift actual voltage of each phase is 0 when the motor driving means is normal. However, in practice, even if the motor driving means is normal, the added value of the shift actual voltage of each phase does not become zero. On the other hand, when the motor driving means is abnormal, the added value of the shift actual voltage of each phase becomes a large value. Therefore, the abnormality determination of the motor driving means can be performed by comparing the added value of the shift actual voltage of each phase with a predetermined first threshold value.

  Further, when the added value of the third-order component removal voltage of each phase is larger than the first threshold value, it is determined that the motor driving means is abnormal, so that the third-order harmonic component is superimposed on the voltage command value. Even if it is, abnormality determination can be performed reliably. If the third harmonic component is superimposed on the voltage command value, the ideal value of the added value of the shifted actual voltage does not become zero. Therefore, in the state where the third harmonic component is not removed from the shifted actual voltage, it is not possible to determine the abnormality of the motor driving means based on the shifted actual voltage. However, the ideal value of the added value of the third-order component removal voltage obtained by removing the third-order harmonic component from the shifted actual voltage is zero. Therefore, the abnormality determination of the motor driving means can be reliably performed by using the tertiary component removal voltage.

  In addition, the neutral point potential can be easily calculated by setting the neutral point potential to a voltage value that is one half of the power supply voltage.

  That is, according to the first aspect of the present invention, it is possible to determine the abnormality of the motor driving means without using a current sensor other than the current sensor necessary for motor control. Furthermore, according to the first aspect of the present invention, it is possible to reliably determine the abnormality of the motor driving means even if there is an influence of the back electromotive voltage of the motor when the motor is rotating at high speed. That is, regardless of the angular velocity of the motor, the abnormality determination of the motor driving means can be performed by comparing the added value of the shift actual voltage (or tertiary component removal voltage) of each phase with the predetermined first threshold value. it can.

(2) Effects of the Second Invention According to the second invention, abnormality detection of motor driving means such as an inverter circuit is performed based on the estimated voltage value and the voltage command value. Specifically, it is determined whether or not the deviation between the estimated voltage value and the voltage command value is greater than a predetermined second threshold value. And when the said deviation is larger than a 2nd threshold value, it determines with it being abnormal in a motor drive means.

  Here, as described above, the estimated voltage value used for abnormality determination is a voltage value applied to the brushless DC motor based on the d / q-axis current command value and the rotation angular velocity. This estimated voltage value is calculated based on a voltage equation of a so-called brushless DC motor. The d / q axis current command value used to calculate the estimated voltage value is an ideal current value to be supplied to the brushless DC motor. The rotational angular velocity used to calculate the estimated voltage value is the actual rotational angular velocity of the brushless DC motor. That is, the estimated voltage value calculated based on the current command value and the rotational angular velocity is an ideal voltage value to be applied to the brushless DC motor in consideration of the rotational driving state of the brushless DC motor. The voltage that can be output by the inverter is limited due to the limitation of the power supply voltage. Therefore, the voltage command value is subjected to saturation determination and guarded. Therefore, a similar saturation determination is performed for the estimated voltage value.

  On the other hand, as described above, the voltage command value used for abnormality determination is a value applied to the brushless DC motor calculated based on a deviation between the d / q axis current command value and the d / q axis actual current. is there. That is, the voltage command value is a voltage value that is actually applied to the brushless DC motor in consideration of the current value actually supplied to the brushless DC motor.

  When the motor driving means is normal, the brushless DC motor performs rotational driving according to the supplied current value. Therefore, the estimated voltage value and the voltage command value ideally match when the motor driving means is normal. Therefore, when the motor driving means is normal, the deviation between the estimated voltage value and the voltage command value is a value close to zero.

  However, in the case of an abnormality such as a short circuit of the inverter circuit in the motor driving means, for example, current does not flow in each phase of the brushless DC motor, and the brushless DC motor may not be driven to rotate normally. . In this case, the estimated voltage value is a small value because the brushless DC motor is not rotationally driven. On the other hand, since no current flows through the brushless DC motor, the voltage command value has a large deviation from the current command value, and the deviation does not decrease indefinitely. That is, in the case of the above abnormality, the estimated voltage value is smaller than the voltage command value, and both are greatly different values. Therefore, by determining whether or not the deviation between the estimated voltage value and the voltage command value is greater than a predetermined second threshold, it is possible to determine whether the motor driving unit is abnormal.

  That is, according to the second aspect of the present invention, it is possible to determine the abnormality of the motor driving means without using a current sensor other than the current sensor necessary for motor control. Furthermore, according to the second aspect of the present invention, even when the motor is rotating at a high speed, even if there is an influence of the counter electromotive voltage of the motor, it is possible to reliably determine the abnormality of the motor driving means. In other words, regardless of the angular velocity of the motor, the abnormality determination of the motor driving means can be performed by comparing the deviation between the estimated voltage value and the voltage command value with the predetermined second threshold value.

  As described above, the abnormality determination can be performed using the voltage value of the d / q-axis component, or can be performed using the voltage value of the three-phase AC component. Of course, the abnormality determination can also be performed using the voltage value of the d / q axis component and the voltage value of the three-phase AC component. Here, when the voltage command value of the three-phase AC component is used, the estimated voltage value of the three-phase AC component is calculated by performing d / q inverse transformation after calculating the estimated voltage value of the d / q-axis component. ing. That is, when the voltage value of the three-phase AC component is used, it is necessary to perform d / q reverse conversion, compared to the case where the voltage value of the d / q axis component is used. That is, it is possible to reduce the arithmetic processing more by using the voltage value of the d / q axis component. Also, by performing abnormality determination using a plurality of voltage values, the accuracy of abnormality determination can be improved more reliably.

(1) First Embodiment Next, the first invention will be described in more detail with reference to the first embodiment. 1st Embodiment demonstrates the case where the motor drive device of 1st this invention is applied to the motor drive device of an electric power steering apparatus.

  FIG. 1 shows a block diagram of the overall configuration of the electric power steering apparatus in the first embodiment. As shown in FIG. 1, the electric power steering apparatus includes a steering torque sensor 1, a vehicle speed sensor 2, and a motor drive device. The motor drive device includes a motor control unit (motor control unit) 3, a motor drive unit (motor drive unit) 4, an assist motor (brushless DC motor) 5, current sensors 6 to 7, a rotation angle sensor 8, A power supply voltage detection unit 9, a phase actual voltage detection unit 10, and an inverter abnormality detection unit 11 are provided.

(1.1) Steering torque sensor 1 and vehicle speed sensor 2
The steering torque sensor 1 is a sensor that detects a steering torque Ts applied to a steering shaft (not shown). Here, the steering shaft connected to the steering wheel includes a torsion bar. A steering torque sensor 1 is attached to the torsion bar. When the steering wheel rotates, a rotational force is applied to the torsion bar, and the torsion bar is twisted according to the applied rotational force. The steering torque applied to the steering shaft corresponding to the twist of the torsion bar is detected by the steering torque sensor 1. The vehicle speed sensor 2 is a sensor that detects the traveling speed Vs of the vehicle. The vehicle speed sensor 2 is attached to the front wheel of the vehicle.

(1.2) Motor control unit (motor control means) 3
The motor control unit 3 outputs a control signal to a motor driving unit 4 described later to control an assist electric motor 5 described later. As shown in FIG. 1, the motor control unit 3 includes a current command value generation unit (current command value generation means) 31, a d-axis subtractor 32, a q-axis subtractor 33, and a PI control unit (d / q Shaft voltage command value calculation means) 34, d / q inverse conversion section (AC voltage command value output means) 35, third harmonic calculation section 36, third order component superimposition section 37, and d / q conversion section 38. It consists of.

(1.2.1) Current command value generating unit (current command value generating means) 31
First, the current command value generation unit 31 inputs the steering torque Ts detected by the steering torque sensor 1 and the vehicle speed Vs detected by the vehicle speed sensor 2. Then, the current command value generation unit 31 performs a phase compensation process for the input steering torque Ts. Based on the steering torque Ts subjected to the phase compensation process and the input vehicle speed Vs, current command values Id * and Iq * which are target currents to be supplied to the assist motor 5 are set. The current command values Id * and Iq * are set based on a current command value map indicating the relationship between the current command values Id * and Iq * with respect to the steering torque Ts and the vehicle speed Vs stored in advance. Here, the current command value Id * is a current command value of the d-axis component of the current command value (hereinafter referred to as “d-axis current command value”). The current command value Iq * is a current command value of the q-axis component of the current command value (hereinafter referred to as “q-axis current command value”). The d-axis is an axis in the field flux direction of the brushless DC motor, and the q-axis is an axis perpendicular to the d-axis.

(1.2.2) d-axis subtractor 32
The d-axis subtractor 32 is a d-axis obtained by subtracting a d-axis actual current Id calculated by a d / q converter 38 (to be described later) from a d-axis current command value Id * set by the current command value generator 31. Deviation current ΔId (= Id * −Id) is calculated.

(1.2.3) q-axis subtractor 33
The q-axis subtractor 33 is a q-axis obtained by subtracting a q-axis actual current Iq calculated by a d / q converter 38, which will be described later, from a q-axis current command value Iq * set by the current command value generator 31. Deviation current ΔIq (= Iq * −Iq) is calculated.

(1.2.4) PI control unit (d / q-axis voltage command value calculation means) 34
The PI control unit 34 uses the d-axis deviation current ΔId calculated by the d-axis subtractor 32 and the q-axis deviation current ΔIq calculated by the q-axis subtractor 33 to apply the d-axis voltage command value Vd applied to the assist motor 5. * And q-axis voltage command value Vq * are calculated. Specifically, the PI control unit 34 determines that the d-axis actual current Id and the q-axis actual current Iq are the d-axis current command value Id * and the q-axis current command value based on the d-axis deviation current ΔId and the q-axis deviation current ΔIq. The d-axis voltage command value Vd * and the q-axis voltage command value Vq * are calculated so as to respectively follow Iq *. Since the inverter can output only a finite voltage, the d-axis voltage command value Vd * and the q-axis voltage command value Vq * are adjusted so as to satisfy the constraint condition of Equation 1.

(1.2.5) d / q inverse converter (AC voltage command value output means) 35
The d / q inverse conversion unit 35 converts the d-axis voltage command value Vd * and the q-axis voltage command value Vq * calculated by the PI control unit 34 into three-phase voltage command values Vu * (1), Vv * (1), Convert to Vw * (1). Here, the three-phase voltage command values Vu * (1), Vv * (1), and Vw * (1) converted by the d / q inverse conversion unit 35 are voltage command values composed of basic sine waves. Vu * (1) is a voltage command value composed of a U-phase basic sine wave, Vv * (1) is a voltage command value composed of a V-phase basic sine wave, and Vw * (1) is a W phase. This is a voltage command value consisting of a basic sine wave.

(1.2.6) Third harmonic operation unit 36
The third harmonic calculation unit 36 is based on the d-axis voltage command value Vd * and the q-axis voltage command value Vq * calculated by the PI control unit 34, and a voltage command value Vn composed of the third harmonic component of the basic sine wave. Is calculated. That is, the voltage command value Vn of the third harmonic component is calculated by Equation 2.

(1.2.7) Third-order component superimposing unit 37
The third-order component superimposing unit 37 applies each of the three-phase voltage command values Vu * (1), Vv * (1), and Vw * (1) composed of the basic sine wave calculated by the d / q inverse converting unit 35. The third-order component superimposed voltage command values Vu * (3), Vv * (3), and Vw * (3) obtained by adding the voltage command value Vn of the third-order harmonic component calculated by the third-order harmonic calculation unit 36 are calculated. is doing. Then, the tertiary component superimposing unit 37 outputs the calculated tertiary component superimposed voltage command values Vu * (3), Vv * (3), and Vw * (3) to the motor driving unit 4 described later. That is, the third-order component superimposed voltage command values Vu * (3), Vv * (3), and Vw * (3) are control signals for driving the motor drive unit 4.

(1.2.8) d / q converter 38
The d / q conversion unit 38 is based on actual currents Iu and Iv detected by current sensors 6 to 7 to be described later and a rotation angle θ detected by the rotation angle sensor 8, and an actual current Id and q-axis component of the d-axis component. The actual current Iq is calculated. Then, the d / q conversion unit 38 outputs the d-axis actual current Id to the d-axis subtraction unit 32 described above, and outputs the q-axis actual current Iq to the q-axis subtraction unit 33 described above.

(1.3) Motor drive section (motor drive means) 4
The motor drive unit 4 drives the assist motor 5 based on the control signal output from the motor control unit 3. As shown in FIG. 1, the motor drive unit 4 includes a PWM conversion unit 41 and an inverter circuit 42.

(1.3.1) PWM converter 41
The PWM conversion unit 41 drives each switching element of the inverter circuit 42 so that the voltage of each phase can be output in the range of 0 to Vb at the maximum based on the control signal output from the adder 37 of the motor control unit 3. PWM signal is generated. Here, as described above, the third harmonic component is superimposed on the control signal output from the adder 37. Therefore, the PWM signal generated by the PWM conversion unit 41 is a signal including a third harmonic component.

(1.3.2) Inverter circuit 42
The inverter circuit 42 is configured by switching elements such as six MOSFETs. A power supply is connected to the input side of the inverter circuit 42 and a power supply voltage Vb is applied. The PWM signal output from the PWM conversion unit 41 is input to the gate of each switching element.

(1.4) Assist electric motor (brushless DC motor) 5
The assist motor 5 generates a steering assist force when current is supplied to each phase from the inverter circuit 42. This assist electric motor 5 consists of a brushless DC motor. The assist motor 5 is connected to the output side of the inverter circuit 42. Specifically, the U-phase winding of the assist motor 5 is connected to an intermediate position of the U-phase arm of the inverter circuit 42. Further, the V phase winding of the assist motor 5 is connected to an intermediate position of the V phase arm of the inverter circuit 42. A W-phase winding of the assist motor 5 is connected to an intermediate position of the W-phase arm of the inverter circuit 42.

(1.5) Current sensors 6-7
U-phase current sensor 6 is arranged between the U-phase arm of inverter circuit 42 and the U-phase winding of assist motor 5. That is, the U-phase current sensor 6 detects the U-phase current Iu supplied to the U-phase winding of the assist motor 5. V-phase current sensor 7 is disposed between the V-phase arm of inverter circuit 42 and the V-phase winding of assist motor 5. That is, the V-phase current sensor 7 detects the V-phase current Iv supplied to the V-phase winding of the assist motor 5. These current sensors 6 to 7 are output to the d / q conversion unit 38 of the motor control unit 3 described above.

(1.6) Rotation angle sensor 8
The rotation angle sensor 8 is a sensor that detects the rotation angle position θ of the rotor of the assist electric motor 5. The rotation angle sensor 8 outputs the detected rotation angle position θ of the rotor of the assist electric motor 5 to the d / q conversion unit 38 of the motor control unit 3 described above.

(1.7) Power supply voltage detector 9
The power supply voltage detector 9 detects the power supply voltage Vb applied to the input side of the inverter circuit 42. And the power supply voltage detection part 9 is outputting the power supply voltage Vb to the inverter abnormality detection part 11 mentioned later.

(1.8) Phase actual voltage detector 10
The phase actual voltage detector 10 detects the actual voltage of each phase of the assist motor 5. That is, the phase actual voltage detector 10 includes a U-phase actual voltage detector that detects the U-phase actual voltage Vu of the assist motor 5, a V-phase actual voltage detector that detects the V-phase actual voltage Vv, and a W-phase actual voltage. It consists of a W-phase actual voltage detector for detecting Vw. The detected phase actual voltages Vu, Vv, and Vw are output to the inverter abnormality detector 11 described later.

(1.9) Inverter abnormality detection unit 11
The inverter abnormality detection unit 11 detects an abnormality of the inverter circuit 42. And the inverter abnormality detection part 11 performs the process of stopping the assist motor 5, etc., for example, when the abnormality of the inverter circuit 42 is detected. As shown in FIG. 1, the inverter abnormality detection unit 11 includes a third harmonic removal unit 111 and an abnormality determination unit 112.

(1.9.1) Third harmonic removal unit 111
The third-order harmonic removal unit 111 is a voltage value Vn of the third-order harmonic component calculated by the third-order harmonic calculation unit 36 of each phase actual voltage Vu, Vv, Vw detected by the phase actual voltage detection unit 10. And the power supply voltage Vb detected by the power supply voltage detection part 9 is input. Then, the third harmonic removing unit 111 performs a process of removing the voltage Vn of the third harmonic component from each phase actual voltage Vu, Vv, Vw detected by the phase actual voltage detecting unit 10. Details of the process of removing the voltage Vn of the third harmonic component from each phase actual voltage Vu, Vv, Vw will be described later.

(1.9.2) Abnormality determination unit 112
The abnormality determination unit 112 determines whether or not the inverter circuit 42 is abnormal based on the voltage value obtained by removing the third harmonic component from each phase actual voltage calculated by the third harmonic removal unit 111. . When the abnormality determination unit 112 determines that the inverter circuit 42 is abnormal, for example, the abnormality determination unit 112 performs abnormality processing such as stopping the assist motor 5. The abnormality determination process will be described later.

(1.10) Operation of Inverter Abnormality Detection Unit 11 Next, the operation of the above-described inverter abnormality detection unit 11 will be described with reference to the flowchart of FIG. FIG. 2 is a flowchart showing the operation of the inverter abnormality detection unit 11.

  As shown in FIG. 2, the third harmonic removal unit 111 of the inverter abnormality detection unit 11 reads the phase actual voltages Vu, Vv, and Vw from the phase actual voltage detection unit 10 (step S1). Subsequently, the power supply voltage Vb is read from the power supply voltage detection unit 9 (step S2).

  Subsequently, based on the read phase actual voltages Vu, Vv, Vw and the power supply voltage Vb, a process of shifting to the difference voltages VuTmp, VvTmp, VwTmp between the phase actual voltage and the neutral point potential is performed (step S3). Specifically, the neutral point potential shift process of the phase actual voltage is performed by Equation 3. That is, the neutral point potential is set to one half of the power supply voltage Vb, and the difference voltage between each phase actual voltage Vu, Vv, Vw and one half of the power supply voltage Vb (hereinafter referred to as “shifted each phase voltage”). ").

  Subsequently, it is determined whether or not the voltage value Vn of the third harmonic component output by the third harmonic calculation unit 36 is 0 (step S4). Here, if the voltage value Vn of the third harmonic component is not 0, it indicates that the third harmonic component is superimposed on the control signal output from the motor control unit 3. On the other hand, when the voltage value Vn of the third harmonic component is 0, it indicates that the third harmonic component is not superimposed on the control signal output from the motor control unit 3.

  If the voltage value Vn output from the third harmonic calculation unit 36 is not 0 (step S4: Yes), the voltage value of the third harmonic component from each phase voltage VuTmp, VvTmp, VwTmp subjected to the shift processing. The process which removes is performed (step S5). That is, as shown in Equation 4, the voltage values Vu ′, Vv ′, Vw ′ obtained by subtracting the voltage value Vn output from the third harmonic calculation unit 36 from the phase-processed voltages VuTmp, VvTmp, VwTmp are obtained. calculate.

  On the other hand, when the voltage value Vn output from the third harmonic calculation unit 36 is 0 (step S4: No), the phase voltages VuTmp, VvTmp, and VwTmp that have been subjected to the shift processing are expressed as shown in Equation 5. It replaces with Vu ′, Vv ′, Vw ′ as it is (step S6). Since the inverter circuit 42 can output only a finite voltage, the voltage estimated value is adjusted by a method similar to the method in which the voltage command value is adjusted so as to satisfy the above-described constraint condition of Equation 1.

  Subsequently, the abnormality determination unit 112 performs an abnormality determination process. Specifically, the absolute value of the added value of the voltage values Vu ′, Vv ′, Vw ′ of each phase calculated in step S5 or step S6 is greater than a predetermined threshold (first threshold) V1 stored in advance. Whether or not (step S7). This predetermined threshold value V1 is a value relatively close to zero.

  If the absolute value of the sum of the voltage values Vu ′, Vv ′, Vw ′ of each phase is larger than the predetermined threshold value V1 (Yes at Step S7), the abnormality counter is set to 1 because the inverter circuit 42 is in an abnormal state. Increase (step S8). On the other hand, if the absolute value of the sum of the voltage values Vu ′, Vv ′, Vw ′ of each phase is equal to or less than the predetermined threshold value V1 (step S7: No), the inverter circuit 42 is not in an abnormal state and clears the abnormal counter. (Step S9).

  Subsequently, it is determined whether or not the abnormality counter has reached a predetermined value n (step S10). When the abnormality counter reaches the predetermined value n, that is, when the abnormality counter reaches the predetermined value n or more (step S10: Yes), an abnormality process is performed (step S11). The abnormality process is, for example, a stop process of the assist motor 5. On the other hand, when the abnormality counter has not reached the predetermined value n, that is, when the abnormality counter is smaller than the predetermined value n (step S10: No), the inverter abnormality detection process is exited.

(2) Second Embodiment Next, the second invention will be described in more detail with reference to a second embodiment. 2nd Embodiment demonstrates the case where the motor drive device of 2nd this invention is applied to the motor drive device of an electric power steering apparatus.

  FIG. 3 shows a block diagram of the overall configuration of the electric power steering apparatus according to the second embodiment. As shown in FIG. 3, the electric power steering apparatus includes a steering torque sensor 1, a vehicle speed sensor 2, and a motor drive device. The motor drive device includes a motor control unit (motor control unit) 12, a motor drive unit (motor drive unit) 4, an assist motor (brushless DC motor) 5, current sensors 6 to 7, a rotation angle sensor 8, And an inverter abnormality detection unit 13. Here, in the electric power steering apparatus according to the second embodiment, the same components as those of the electric power steering apparatus according to the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted.

(2.1) Motor control unit (motor control means) 12
The motor control unit 12 outputs a control signal to the motor driving unit 4 to control the assist motor 5. As shown in FIG. 3, the motor controller 12 includes a current command value generator (current command value generator) 31, a d-axis subtractor 32, a q-axis subtractor 33, and a PI controller (d / q A shaft voltage command value calculation means) 34, a d / q inverse conversion unit (AC voltage command value output means) 35, a d / q conversion unit 38, and an angular velocity calculation unit (angular velocity detection means) 121.

  As described in the first embodiment, the current command value generation unit 31 uses the d-axis current command values Id * and q, which are target currents to be supplied to the assist motor 5 based on the steering torque Ts and the input vehicle speed Vs. Set shaft current command value Iq *. The set d-axis current command value Id * and q-axis current command value Iq * are output to the subtractors 32 and 33 described above, and the d / q-axis estimated voltage value calculation of the inverter abnormality detection unit 13 described later is performed. Output to the unit 131.

  As described in the first embodiment, the d / q inverse conversion unit 35 converts the d-axis voltage command value Vd * and the q-axis voltage command value Vq * calculated by the PI control unit 34 into the three-phase voltage command value Vu *. , Vv *, Vw *. The converted three-phase voltage command values Vu *, Vv *, and Vw * are output to the PWM conversion unit 41 of the motor drive unit 4 described above.

  The angular velocity calculation unit 121 inputs the rotation angle position θ of the rotor of the assist motor 5 detected by the rotation angle sensor 8. Then, the angular velocity calculating unit 121 calculates the rotational angular velocity ω of the rotor of the assist motor 5 by differentiating the input rotational angular position θ. Then, the angular velocity calculation unit 121 outputs the calculated rotation angular velocity ω to the d / q axis estimated voltage value calculation unit 131 of the inverter abnormality detection unit 13 described later.

(2.2) Inverter abnormality detector 13
The inverter abnormality detection unit 13 detects an abnormality of the inverter circuit 42. And the inverter abnormality detection part 13 performs the process of stopping the assist motor 5, etc., for example, when the abnormality of the inverter circuit 42 is detected. As shown in FIG. 3, the inverter abnormality detection unit 13 includes a d / q axis estimated voltage value calculation unit 131 and an abnormality determination unit 132.

(2.2.1) d / q axis estimated voltage value calculation unit 131
The d / q-axis estimated voltage value calculation unit 131 outputs the d-axis current command value Id * and the q-axis current command value Iq * output from the current command value generation unit 31 of the motor control unit 12 and the angular velocity calculation unit 121. Rotational angular velocity ω to be inputted. Then, the d-axis estimated voltage value Vdh and the q-axis estimated voltage value Vqh are calculated according to the d-axis current command value Id *, the q-axis current command value Iq *, the rotational angular velocity ω, and the motor voltage equation of Equation 6.

(2.2.2) Abnormality determination unit 132
The abnormality determination unit 132 includes the d-axis estimated voltage value Vdh and the q-axis estimated voltage value Vqh calculated by the d / q-axis estimated voltage value calculation unit 131, and the d-axis voltage command value Vd * calculated by the PI control unit 34. And q-axis voltage command value Vq *. Then, based on the input estimated voltage values Vdh and Vqh and the voltage command values Vd * and Vq *, it is determined whether or not the inverter circuit 42 is abnormal. When the abnormality determination unit 132 determines that the inverter circuit 42 is abnormal, for example, the abnormality determination unit 132 performs abnormality processing such as stopping the assist motor 5. The abnormality determination process will be described later.

(2.3) Operation of Inverter Abnormality Detection Unit 13 Next, the operation of the above-described inverter abnormality detection unit 13 will be described with reference to the flowchart of FIG. FIG. 4 is a flowchart showing the operation of the inverter abnormality detection unit 13.

  As shown in FIG. 4, the d / q axis estimated voltage value calculation unit 131 of the inverter abnormality detection unit 13 reads the rotational angular velocity ω of the rotor of the assist motor 5 from the angular velocity calculation unit 121 (step S21). Subsequently, the d-axis current command value Id * and the q-axis current command value Iq * are read from the current command value generation unit 31 (step S22). Subsequently, the d-axis estimated voltage value Vdh and the q-axis estimated voltage value Vqh are calculated according to the motor voltage equation shown in the above equation 6 (step S23). Then, the d / q-axis estimated voltage value calculation unit 131 outputs the calculated d-axis estimated voltage value Vdh and q-axis estimated voltage value Vqh to the abnormality determination unit 132 of the inverter abnormality detection unit 13.

  Subsequently, the abnormality determination unit 132 of the inverter abnormality detection unit 13 performs abnormality determination processing. Specifically, first, the d-axis voltage command value Vd * and the q-axis voltage command value Vq * are read from the PI control unit 34 (step S24). Subsequently, whether or not the absolute value of the differential voltage between the d-axis voltage command value Vd * and the d-axis estimated voltage value Vdh (hereinafter referred to as “d-axis differential voltage”) is greater than a predetermined threshold (second threshold) V2. Is determined (step S25). Alternatively, whether or not the absolute value of the difference voltage between the q-axis voltage command value Vq * and the q-axis estimated voltage value Vqh (hereinafter referred to as “q-axis difference voltage”) is greater than a predetermined threshold (second threshold) V3. Determination is made (step S25).

  When the d-axis difference voltage is larger than the predetermined threshold V2 or when the q-axis difference voltage is larger than the predetermined threshold V3 (step S25: Yes), the abnormality counter is incremented by 1 because the inverter circuit 42 is in an abnormal state. (Step S26). On the other hand, when the d-axis difference voltage is equal to or less than the predetermined threshold value V2 and the q-axis difference voltage is equal to or less than the predetermined threshold value V3 (step S25: No), the inverter circuit 42 clears the abnormality counter as not being in an abnormal state. (Step S27).

  Subsequently, it is determined whether or not the abnormality counter has reached a predetermined value n (step S28). When the abnormality counter reaches the predetermined value n, that is, when the abnormality counter reaches the predetermined value n or more (step S28: Yes), an abnormality process is performed (step S29). The abnormality process is, for example, a stop process of the assist motor 5. On the other hand, if the abnormality counter has not reached the predetermined value n, that is, if the abnormality counter is smaller than the predetermined value n (step S28: No), the inverter abnormality detection process is exited.

(3) Third Embodiment Next, a third embodiment will be described as another embodiment of the second invention and will be described in more detail. In the third embodiment, a case where another motor driving device of the second invention is applied to a motor driving device of an electric power steering device will be described.

  FIG. 5 shows a block diagram of the overall configuration of the electric power steering apparatus in the third embodiment. As shown in FIG. 5, the electric power steering device includes a steering torque sensor 1, a vehicle speed sensor 2, and a motor drive device. The motor drive device includes a motor control unit (motor control unit) 12, a motor drive unit (motor drive unit) 4, an assist motor (brushless DC motor) 5, current sensors 6 to 7, a rotation angle sensor 8, And an inverter abnormality detection unit 14. Here, in the electric power steering apparatus according to the third embodiment, the same components as those of the electric power steering apparatus according to the first embodiment and the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

(3.1) Motor control unit (motor control means) 12
The motor control unit 12 is substantially the same as the motor control unit 12 in the second embodiment. However, the d / q inverse conversion unit 35 outputs the three-phase voltage command values Vu *, Vv *, and Vw * to the PWM conversion unit 41 and also outputs them to the abnormality determination unit 142 of the inverter abnormality detection unit 14 described later. Yes.

(3.2) Inverter abnormality detection unit 14
The inverter abnormality detection unit 14 detects an abnormality of the inverter circuit 42. And the inverter abnormality detection part 14 performs the process of stopping the assist motor 5, for example, when the abnormality of the inverter circuit 42 is detected. As shown in FIG. 5, the inverter abnormality detection unit 14 includes an estimated voltage value calculation unit 141 and an abnormality determination unit 142. The estimated voltage value calculation unit 141 includes a d / q axis estimated voltage value calculation unit 131 and an AC estimated voltage value calculation unit 143.

(3.2.1) Estimated voltage value calculation unit 141
As described above, the estimated voltage value calculation unit 141 includes the d / q axis estimated voltage value calculation unit 131 and the AC estimated voltage value calculation unit 143. The d / q-axis estimated voltage value calculation unit 131 outputs the d-axis current command value Id * and the q-axis current command value Iq * output from the current command value generation unit 31 of the motor control unit 12 and the angular velocity calculation unit 121. Rotational angular velocity ω to be inputted. Then, the d-axis estimated voltage value Vdh and the q-axis estimated voltage value Vqh are calculated according to the d-axis current command value Id *, the q-axis current command value Iq *, the rotational angular velocity ω, and the motor voltage equation of the above formula 6. .

  The AC estimated voltage value calculation unit 143 is based on the d-axis estimated voltage value Vdh and the q-axis estimated voltage value Vqh calculated by the d / q-axis estimated voltage value calculation unit 131, and the three-phase AC estimated voltage values Vuh, Vvh, Vqh. Is calculated. The AC estimated voltage value calculation unit 143 performs the same processing as the d / q inverse conversion unit 35 of the motor control unit 12. Vuh is an estimated U-phase voltage value, Vvh is an estimated V-phase voltage value, and Vwh is an estimated W-phase voltage value.

(3.2.2) Abnormality determination unit 142
Abnormality determination unit 142 receives U-phase estimated voltage value Vuh, V-phase estimated voltage value Vvh, and W-phase estimated voltage value Vwh from AC estimated voltage value calculation unit 143. Further, a U-phase voltage command value Vu *, a V-phase voltage command value Vv *, and a W-phase voltage command value Vw * are input from the d / q inverse conversion unit 35. Then, based on the inputted estimated voltage values Vuh, Vvh, Vwh and voltage command values Vu *, Vv *, Vw *, it is determined whether or not the inverter circuit 42 is abnormal. When the abnormality determination unit 142 determines that the inverter circuit 42 is abnormal, for example, the abnormality determination unit 142 performs abnormality processing such as stopping the assist motor 5. The abnormality determination process will be described later.

(3.3) Operation of Inverter Abnormality Detection Unit 14 Next, the operation of the above-described inverter abnormality detection unit 14 will be described with reference to the flowchart of FIG. FIG. 6 is a flowchart showing the operation of the inverter abnormality detection unit 14.

  As shown in FIG. 6, the d / q axis estimated voltage value calculation unit 131 of the inverter abnormality detection unit 14 reads the rotational angular velocity ω of the rotor of the assist motor 5 from the angular velocity calculation unit 121 (step S31). Subsequently, the d-axis current command value Id * and the q-axis current command value Iq * are read from the current command value generation unit 31 (step S32). Subsequently, the d-axis estimated voltage value Vdh and the q-axis estimated voltage value Vqh are calculated according to the motor voltage equation shown in the above equation 6 (step S33). Then, the d / q-axis estimated voltage value calculation unit 131 outputs the calculated d-axis estimated voltage value Vdh and q-axis estimated voltage value Vqh to the AC estimated voltage value calculation unit 143.

  Subsequently, in the AC estimated voltage value calculation unit 143, based on the d-axis estimated voltage value Vqh and the q-axis estimated voltage value Vqh, the U-phase estimated voltage value Vuh, the V-phase estimated voltage value Vvh, and the W-phase estimated voltage value Vwh. Is calculated (step S34). Then, AC estimated voltage value calculation unit 143 outputs the calculated U phase estimated voltage value Vuh, V phase estimated voltage value Vvh, and W phase estimated voltage value Vwh to abnormality determination unit 143.

  Subsequently, the abnormality determination unit 142 of the inverter abnormality detection unit 14 performs abnormality determination processing. Specifically, first, the U-phase voltage command value Vu *, the V-phase voltage command value Vv *, and the W-phase voltage command value Vw * are read from the d / q inverse conversion unit 35 (step S35). Subsequently, whether or not the absolute value of the difference voltage between the U-phase voltage command value Vu * and the U-phase estimated voltage value Vuh (hereinafter referred to as “U-phase difference voltage”) is greater than a predetermined threshold (second threshold) V4. Determination is made (step S36). Alternatively, it is determined whether or not the absolute value of the difference voltage between the V-phase voltage command value Vv * and the V-phase estimated voltage value Vvh (hereinafter referred to as “V-phase difference voltage”) is greater than a predetermined threshold (second threshold) V5. (Step S36). Alternatively, it is determined whether or not the absolute value of the difference voltage between the W-phase voltage command value Vw * and the W-phase estimated voltage value Vwh (hereinafter referred to as “W-phase difference voltage”) is greater than a predetermined threshold (second threshold) V6. (Step S36).

  When the U phase difference voltage is larger than the predetermined threshold V4, when the V phase difference voltage is larger than the predetermined threshold V5, or when the W phase difference voltage is larger than the predetermined threshold V6 (step S36: Yes), the inverter circuit 42 is abnormal. The abnormal counter is incremented by 1 because it is in a state (step S37). On the other hand, when the U phase difference voltage is equal to or lower than the predetermined threshold V4, the V phase difference voltage is equal to or lower than the predetermined threshold V5, and the W phase difference voltage is equal to or lower than the predetermined threshold V6 (step S36: No), the inverter circuit 42 is not abnormal and the abnormal counter is cleared (step S38).

  Subsequently, it is determined whether or not the abnormality counter has reached a predetermined value n (step S39). When the abnormality counter reaches the predetermined value n, that is, when the abnormality counter reaches the predetermined value n or more (step S39: Yes), an abnormality process is performed (step S40). The abnormality process is, for example, a stop process of the assist motor 5. On the other hand, when the abnormality counter has not reached the predetermined value n, that is, when the abnormality counter is smaller than the predetermined value n (step S39: No), the inverter abnormality detection process is exited.

1 shows an overall configuration of an electric power steering apparatus according to a first embodiment. It is a flowchart which shows operation | movement of the inverter abnormality detection part 11 of 1st Embodiment. The whole structure of the electric power steering device of 2nd Embodiment is shown. It is a flowchart which shows operation | movement of the inverter abnormality detection part 13 of 2nd Embodiment. The whole structure of the electric power steering device of 3rd Embodiment is shown. It is a flowchart which shows operation | movement of the inverter abnormality detection part 14 of 3rd Embodiment.

Explanation of symbols

1: Steering torque sensor, 2: Vehicle speed sensor, 3, 12: Motor control unit (motor control unit) 3, 4: Motor drive unit (motor drive unit), 5: Assist electric motor (brushless DC motor), 6, 7: Current sensor, 8: rotation angle sensor, 9: power supply voltage detector, 10: phase actual voltage detector, 11, 13, 14: inverter abnormality detector, 31: current command value generator (current command value generator), 32: d-axis subtractor, 33: q-axis subtractor, 34: PI control unit (d / q-axis voltage command value calculation means), 35: d / q inverse conversion unit (AC voltage command value output means), 36: 3rd harmonic calculation unit, 37: 3rd order component superimposition unit, 38: d / q conversion unit

Claims (6)

A brushless DC motor;
Motor driving means for driving the brushless DC motor by applying an AC voltage to each phase of the brushless DC motor;
Motor control means for controlling the brushless DC motor by outputting a control signal to the motor driving means;
In a motor drive device comprising:
Furthermore, an actual voltage detecting means for detecting an actual voltage of each phase of the brushless DC motor;
Shift actual voltage calculation means for calculating a shift actual voltage of each phase that is a difference voltage between the detected actual voltage of each phase and a neutral point potential;
An abnormality determining means for determining that the motor driving means is abnormal when an added value of the shift actual voltage of each phase is larger than a predetermined first threshold;
A motor drive device comprising: The control signal is a third superimposed voltage command value in which a third harmonic component of the basic sine wave is superimposed on a voltage command value composed of a basic sine wave,
Furthermore, it comprises third-order component removal voltage calculation means for calculating a third-order component removal voltage of each phase from which the third-order harmonic component has been removed from the shifted actual voltage of each phase,
2. The motor drive according to claim 1, wherein the abnormality determination unit determines that the motor drive unit is abnormal when an added value of the tertiary component removal voltage of each phase is larger than the first threshold value. apparatus. Furthermore, power supply voltage detection means for detecting a power supply voltage applied to the motor drive means,
Neutral point potential calculating means for calculating a half voltage value of the power supply voltage and setting the half voltage value as the neutral point potential;
The motor drive device according to claim 1, wherein the motor drive device is provided. A brushless DC motor;
Motor driving means for driving the brushless DC motor by applying an AC voltage to each phase of the brushless DC motor;
Of the actual current flowing through the brushless DC motor, a d / q-axis actual current consisting of a d-axis actual current that is an actual current of a d-axis component and a q-axis actual current that is an actual current of a q-axis component orthogonal to the d-axis D / q-axis actual current calculating means for calculating;
A d / q-axis current command value including a d-axis current command value that is a current command value of the d-axis component supplied to the brushless DC motor and a q-axis current command value that is a current command value of the q-axis component is generated. Current command value generating means;
A voltage command value to be applied to the brushless DC motor is calculated based on a deviation between the d / q-axis current command value and the d / q-axis actual current, and a control signal composed of the voltage command value is output to the motor driving means. Control signal output means;
In a motor drive device comprising:
Furthermore, angular velocity detection means for detecting the rotational angular velocity of the brushless DC motor;
Estimated voltage value calculating means for calculating an estimated voltage value applied to the brushless DC motor based on the d / q-axis current command value and the rotational angular velocity;
An abnormality determining unit that determines that the motor driving unit is abnormal when a deviation between the estimated voltage value and the voltage command value is greater than a predetermined second threshold;
A motor drive device comprising: The control signal output means includes
A d-axis voltage command value that is a voltage command value of the d-axis component applied to the brushless DC motor based on a deviation between the d / q-axis current command value and the d / q-axis actual current, and a voltage of the q-axis component. D / q-axis voltage command value calculating means for calculating a d / q-axis voltage command value comprising a q-axis voltage command value that is a command value;
AC voltage command value output means for calculating an AC voltage command value for each phase of the brushless DC motor based on the d / q axis voltage command value and outputting a control signal composed of the AC voltage command value to the motor driving means. Prepared,
The estimated voltage value is at least one of an estimated voltage value of the d-axis component and an estimated voltage value of the q-axis component,
The abnormality determination means has at least one of a deviation between the estimated voltage value of the d-axis component and the d-axis voltage command value and a deviation between the estimated voltage value of the q-axis component and the q-axis voltage command value. 5. The motor driving device according to claim 4, wherein the motor driving means is determined to be abnormal when larger than a second threshold value. The control signal output means includes
A d-axis voltage command value that is a voltage command value of the d-axis component applied to the brushless DC motor based on a deviation between the d / q-axis current command value and the d / q-axis actual current, and a voltage of the q-axis component. D / q-axis voltage command value calculating means for calculating a d / q-axis voltage command value comprising a q-axis voltage command value that is a command value;
AC voltage command value output means for calculating an AC voltage command value for each phase of the brushless DC motor based on the d / q axis voltage command value and outputting a control signal composed of the AC voltage command value to the motor driving means. Prepared,
The estimated voltage value is an AC estimated voltage value applied to at least one of the phases of the brushless DC motor,
The abnormality determining unit determines that the motor driving unit is abnormal when a deviation between the estimated AC voltage value and the AC voltage command value corresponding to the phase of the estimated AC voltage value is larger than the second threshold value. The motor driving device according to claim 4.

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