JP2013106424A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position sensorless motor controller with open-phase detection means that can suppress erroneous detection and detect hunger with high precision.SOLUTION: The motor controller, having an inverter main circuit 2 that outputs a three-phase AC voltage for driving a synchronous motor 3 and current detection means 6 that detects an electric current running through each phase of a synchronous motor, has a synchronous operation mode for operating the synchronous motor according to a predetermined command value and a running mode by position feedback and includes open-phase detection means 10 that detects an open phase on the basis of a current value detected by the current detection means in the running mode.

Description

  The present invention relates to a motor control device used for an air conditioner, a ventilation fan, a pump, and the like.

  Conventionally, a fan motor such as an air conditioner or a ventilation fan has a position sensor, and it can be determined that a phase failure has occurred based on position information of the position sensor.

  Further, Patent Document 1 discloses a conventional phase loss detection method for a motor control device. In the conventional example, the maximum value of the motor current of an arbitrary phase is determined after a lapse of a predetermined time from the start, and it is determined that the phase is missing when it is continuously below the reference value for a predetermined time. Further, a method is disclosed in which a phase loss is not erroneously detected even when the motor phase current is unbalanced.

JP 2009-189199 A

  In a motor equipped with a position sensor, if there is only one phase, the motor may rotate. Therefore, there is a problem that the position information cannot be detected and the motor continues to be driven in the phase failure state. It was. If driving is continued in an open phase state, a problem of noise and a load on a specific output device of the three-phase inverter may increase, which may lead to destruction.

  Further, in the case of the motor control device of Patent Document 1, since the determination is performed based on the information on the maximum value of the motor current, the motor current becomes small when the load is small, and there is a problem that the motor is erroneously detected and the motor is stopped. It was.

  The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a motor control device that can reduce erroneous detection of phase loss and improve detection accuracy.

  In order to solve the above problems, a motor control device according to the present invention includes a three-phase inverter that outputs a three-phase AC voltage for driving a synchronous motor, and a current detection unit that detects a current flowing in each phase of the synchronous motor. A synchronous operation mode in which the synchronous motor is operated by a predetermined command value, and an operation mode by position feedback, and based on a current value detected by the current detection means during the synchronous operation mode. Open phase detecting means for detecting open phase.

  A motor control device according to the present invention is a motor control device including a three-phase inverter that outputs a three-phase AC voltage for driving a synchronous motor, and a current detection unit that detects a current flowing in each phase of the motor. And an open phase detecting means for detecting an open phase based on the current value detected by the current detecting means when the current command value for calculating the command value of the three-phase AC voltage is larger than a predetermined value.

  According to the present invention, a phase loss can be reliably detected even in motor control without a position sensor. Further, in spite of the phase loss state, the phase loss can be detected even when the motor rotates, and erroneous detection of phase loss can be prevented even when the load is small.

1 is a block diagram of a motor control apparatus according to a first embodiment of the present invention. The wave form diagram for demonstrating the method to reproduce motor current from direct current. The block block diagram of a motor control part. The simplification figure for demonstrating the transition to each operation mode. The simplified diagram for demonstrating the relationship between a motor current and a threshold value. The process flow figure of a phase-loss detection means. The block diagram of the motor control apparatus which is the 2nd Example of this invention. The block diagram of the motor control apparatus which is the 3rd Example of this invention. The whole block diagram of the motor control apparatus which is the 4th Example of this invention. The simplified diagram for demonstrating the open phase detection operating condition in the 5th Example of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing the overall configuration of the motor control apparatus according to the first embodiment of the present invention. The motor control device of the present embodiment can be applied to a fan motor control device used for an indoor unit and an outdoor unit of an air conditioner, a ventilation fan, an air cleaner, or the like.

  In addition, there are cases where a position sensor cannot be attached structurally or environmentally with a compressor or a pump. Even for such applications, the present embodiment provides a reliable and low-cost phase loss detection means.

<Description of overall configuration>
In FIG. 1, a DC power source 1 supplies power to an inverter main circuit 2, for example, has a high voltage of about 141 [V] to about 450 [V]. For example, it rectifies and smoothes an AC voltage from a commercial power source. Obtained from converters and batteries. The inverter main circuit 2 connects two switching elements (T1 to T3 and T4 to T6) in each phase in series between the DC input terminals, and uses these series connection points as three-phase AC terminals. Here, T1 is a U-phase upper arm switching element, T2 is a V-phase upper arm switching element, T3 is a W-phase upper arm switching element, T4 is a U-phase lower arm switching element, T5 is a V-phase lower arm switching element, and T6 is W-phase lower arm switching element. As the switching elements T1 to T6, known semiconductor switching elements such as IGBTs, MOSFETs or bipolar transistors are used.

  The switching diodes T1 to T6 are respectively connected to freewheeling diodes D1 to D6 in antiparallel. Here, D1 is a U-phase upper arm return diode, D2 is a V-phase upper arm return diode, D3 is a W-phase upper arm return diode, D4 is a U-phase lower arm return diode, D5 is a V-phase lower arm return diode, and D6 is W-phase lower arm reflux diode. As the diodes D1 to D6, known semiconductor diodes such as pn junction diodes and Schottky barrier diodes are used. Further, the switching elements T1 to T6 may incorporate the diodes D1 to D6.

  The inverter main circuit 2 generates a three-phase AC voltage based on the power supplied from the DC power supply 1 and the gate drive signal from the gate drive circuit 4 and supplies the three-phase AC voltage to the synchronous motor 3. The gate drive signal is generated according to the drive signal output from the control unit 5.

  The synchronous motor 3 is rotationally driven by the AC power supplied from the inverter main circuit 2 and drives the mechanical load 200. Examples of the mechanical load 200 include a fan, a blower, a compressor driving device, and a pump that are used in an air conditioner, a ventilation fan, or an air purifier. In the present embodiment, a permanent magnet motor (PM motor) is used as the synchronous motor 3.

  The control unit 5 can be realized by, for example, a microcomputer (hereinafter abbreviated as a microcomputer), a digital signal processor (DSP), or the like. In this embodiment, a microcomputer is used.

<Description of current detection means>
As shown in FIG. 1, the current detection means 6 includes an inverter DC bus shunt resistor 7, a current detection circuit 8 for detecting an inverter input DC current IDC flowing through the shunt resistor 7, and an inverter input detected by the current detection circuit 8. The motor current reproduction computing unit 9 reproduces a three-phase alternating current (Iu, Iv, Iw) from the direct current IDC. The reproduced three-phase alternating current (Iu, Iv, Iw) is output to the phase loss detection means 10 and the motor control unit 11.

  The current detection circuit 8 that detects the inverter input DC current IDC amplifies the voltage across the shunt resistor 7 with an operational amplifier such as an operational amplifier. In the control unit 5, the input signal is converted into a digital value by an A / D converter built in the microcomputer and used.

  In general, the shunt resistor 7 of the inverter DC bus is often provided for overcurrent protection. In that case, it is not necessary to newly add a shunt resistor for current detection, and the number of parts can be reduced and the space can be saved. Further, since the shunt resistor 7 and the current detection circuit 8 can be used for both the position sensorless mode described later and current detection for phase loss detection, no special circuit is required for phase loss detection.

  Next, a motor current reproduction calculator 9 that reproduces a three-phase AC current (Iu, Iv, Iw) from the inverter input DC current IDC detected by the current detection circuit 8 will be described with reference to FIG. FIG. 2 shows a reference triangular wave 100, voltage command signals (101a, 101b, 101c) for each phase, PWM pulse signals (22a, 22b, 22c) serving as inverter drive signals for each phase, and input currents (102a for each phase). ˜102d) and the inverter input DC current IDC flowing through the shunt resistor 7. As can be seen from FIG. 2, the inverter input DC current IDC changes according to the state of the switching element of each phase. In FIG. 2, the drive signals (22a, 22b, 22c) of each phase switching element are turned on for the upper arm of each phase when at the high level, and are turned on for the lower arm of each phase when at the low level. Means that. Actually, an independent PWM pulse signal is applied to the upper arm and the lower arm of each phase to control the switching operation. However, FIG. Further, in FIG. 2, for the sake of explanation, the dead time is not provided, but actually, the dead time is provided so that the upper and lower arms of each phase are not short-circuited.

  In FIG. 2, in the sections A and D in which only the W phase has the lower arm on and the U phase and V phase upper arms are on, the W-phase input current having the opposite polarity can be observed. Further, in the sections B and C in which the lower arms of the V phase and the W phase are turned on and only the U phase is turned on, the U-phase input current having the same polarity can be observed.

  In this way, the inverter input DC current IDC that changes according to the state of the switching element of each phase is observed in the A to D sections, and the inverter input DC current IDC in each section is combined to obtain the three-phase AC motor current. Can be reproduced.

<Description of motor controller>
Next, the motor control unit will be described with reference to FIG.

  The motor control unit 11 converts the current (Iu, Iv, Iw) of each phase of the motor detected by the current detection unit 6 from the three-phase axis to the control axis using the estimated magnetic pole position θdc, and converts the d-axis detection current. 3φ / dq converter 15 for obtaining Idc and q-axis detection current Iqc, first-order lag filter 16 for creating q-axis current command Iq * in a position sensorless mode, which will be described later, from Iqc, and d-axis detection currents Idc and q The axis detection current Iqc, the d-axis voltage command value Vd *, and the q-axis voltage command value Vq * are input, and the real rotation position (actual rotation coordinate axis) and virtual rotation position (control axis) of the rotor of the synchronous motor 3 The difference between the axis error calculator 17 for calculating the position error (axis error Δθc) and the axis error Δθc and the axis error command value Δθ * (usually zero) is obtained by the subtractor 18, and the inverter frequency is set so that this becomes zero. Adjust ω1 PLL controller 19, vector change control switch (20a and 20b) for switching between positioning mode, synchronous operation mode, and position sensorless mode, and Id * and Iq * and inverter frequency command value ω1 *. Voltage command calculator 13 that outputs Vd * and Vq *, and three-phase voltage command values (Vu *, Vq *) that Vd * and Vq * are coordinate-converted from the control axis to the three-phase axis and output to the motor signal forming unit. Vv *, Vw *) and a dq / 3φ converter 14 and an integrator 21 that integrates the inverter frequency ω1 and outputs the estimated magnetic pole position θdc.

  The motor control unit 11 outputs a three-phase voltage command value to be output to the motor so that the motor rotates in the vicinity of the rotation speed indicated by the speed command value (inverter frequency command value) ω1 * input from the outside of the motor control unit 11. Calculate. The arithmetic expression will be briefly described below.

Vd * and Vq * calculated by the voltage command calculator 13 are given by equations (1) and (2).
Vd * = r · Id * −ω1 * · Lq · Iq * (1)
Vq * = r · Iq * + ω1 * · Ld · Id * + ω1 * · Ke (2)
Here, r: winding resistance, Ld: d-axis inductance, Lq: q-axis inductance, Ke: power generation constant.

  The dq / 3φ converter 14 converts the coordinates of Vd * and Vq * into a three-phase voltage command value using equations (3) to (7).

Vu * = V1 × cos θv (3)
Vv * = V1 × cos (θv−2 / 3π) (4)
Vw * = V1 × cos (θv + 2 / 3π) (5)
here,
θv = δ + π / 2 + θd (6)
δ = tan−1 (−Vd * / Vq *) (7)
The axis error calculator 17 calculates the axis error Δθc using the d-axis detection current Idc, the q-axis detection current Iqc, and Vd * and Vq * from the voltage command calculator 13. The shaft error Δθc is subtracted from a preset shaft error command value Δθ * (usually zero) in the subtractor 18, and this subtraction value (difference) is proportionally controlled by the PLL controller 19, whereby the detection frequency ωpll is set. can get. In the position sensorless mode, which will be described later, the detected frequency ωpl1 is set to the inverter frequency ω1, and this is integrated by the integrator 21, whereby the magnetic pole position of the synchronous motor 3 can be estimated. The estimated magnetic pole position θdc by this estimation is input to the dq / 3φ converter 14 and the 3φ / dq converter 15 and used for the calculation of each block.

  That is, in the motor control unit 11 in the present embodiment, the axis error Δθc between the actual rotation coordinate axis of the rotor of the synchronous motor 3 and the control axis is calculated, and in other words, the calculated axis error Δθc becomes zero. The inverter frequency ω1 is corrected using a PLL (Phase Locked Loop) method so that the control axis is the same as the actual rotational coordinate axis of the rotor of the synchronous motor 3, and the magnetic pole position is estimated.

<Description of basic operation of motor start-up>
The basic operation when starting the synchronous motor 3 will be described. FIG. 4 is a simplified diagram showing the transition of each operation mode when the synchronous motor 3 is started from a stopped state. The operation mode of the synchronous motor 3 includes a positioning mode in which a direct current is gradually passed through a motor winding of an arbitrary phase to fix the rotor of the synchronous motor 3 at a certain position, and a predetermined value given from an external control device or the like. Alternatively, a voltage to be applied to the synchronous motor 3 is determined according to a predetermined pattern of the d-axis current command value Id *, the q-axis current command value Iq *, and the frequency command ω *, that is, position (estimated position in this embodiment) feedback is performed. There are three modes: a non-synchronous operation mode and a position sensorless mode by adjusting the inverter frequency ω1 so that the axis error Δθc becomes zero, that is, a position feedback mode.

  In these operation modes, any one of the d-axis current command value Id *, the q-axis current command value Iq *, and the inverter frequency ω1 is changed, or the control changeover switches (20a and 20b) in the motor control unit 11 are switched. Transition to another operation mode. Note that the two control changeover switches (20a and 20b) are simultaneously switched unless otherwise specified.

  In the positioning mode, the inverter frequency command value ω1 * is set to zero in order to pass a direct current to the synchronous motor 3.

  After the positioning mode ends, the mode changes to the synchronous operation mode. The control changeover switches (20a and 20b) remain on the A side. In the synchronous operation mode, the d-axis current command value Id * is kept constant and the inverter frequency command value ω1 * is increased. Here, the q-axis current command value Iq * is set to Iq0 * (for example, 0 as shown in FIG. 4). As a result, the synchronous motor 3 accelerates following the inverter frequency command value ω1 *. Thereafter, the acceleration is stopped when the frequency at which position sensorless operation is possible is reached, and the speed is kept constant for a predetermined period of time.

  After the predetermined time elapses, the control changeover switches (20a and 20b) are set to the B side to shift to the position sensorless mode. As a result, the q-axis current command value (Iq *) is switched to the q-axis detection current Iqc passed through the first-order lag filter 16, and the difference between the axis error Δθc and the axis error command value Δθ * (usually zero). PLL controller 19 adjusts inverter frequency ω1 so that becomes zero.

  Here, FIG. 4 and the above description are examples, and the d-axis current command Id *, the q-axis current command Iq *, and the frequency command value ω1 * may differ in value and manner of change depending on the load and application. .

  When starting from a state where the motor is stopped, the motor starts from the positioning mode. However, since a fan motor or the like has a large inertia, when the motor is restarted after the inverter is stopped, the motor may be rotated or may be started from a state where the motor is rotated by an external wind. In this case, there is a problem that it takes time to start up if the motor is stopped. In addition, when the outside wind is strong, the current required to stop the motor during positioning increases, and the motor may not be stopped. For this reason, a fan motor or the like may be started from the synchronous operation mode without using the positioning mode when the motor is rotating before the start. In this embodiment, since the phase loss is detected during the synchronous operation mode, the phase loss can be detected even in such a case. Here, as a method for detecting the rotational speed and the magnetic pole position before activation, there is a known method for generating a phase signal from a back electromotive force (see, for example, JP-A-2005-137106).

  Also, in applications that start from a state where the motor is always stopped like a compressor, in order to detect a phase loss before transitioning to the position sensorless mode by detecting a phase loss during the synchronous operation mode, An open phase can be detected at an early stage.

<Explanation of phase loss detection operation>
The phase loss detection operation will be described. The phase loss detection means determines that the phase is missing when the current of each phase of the motor is not flowing in the synchronous operation mode. In the present embodiment, when the absolute value of the current of each phase output from the current detection means 6 is equal to or less than the threshold value for a predetermined time Ta, the phase is determined to be missing.

  Here, since the current of each phase is an alternating current amount and there is a period that is equal to or less than the threshold value even if the phase is not open, as shown in FIG. 5, the predetermined time Ta for detecting the open phase is the inverter cycle (2π / ω1 *) is taken into consideration. For example, Ta may be set to the inverter cycle, but when an open phase is determined from the absolute value of the current as in this embodiment, it can be set to a half cycle of the inverter cycle. For this reason, Ta can be set by limiting the inverter frequency command value ω1 * during the phase loss detection period by detecting phase loss within a predetermined speed range.

  Furthermore, by detecting the phase loss during the constant speed period provided in the synchronous operation mode, ω1 * can be further specified, and Ta can be set more optimally.

  In addition, by detecting phase loss during a predetermined period immediately before switching from synchronous operation mode to position sensorless mode, phase loss is detected at the highest inverter frequency in synchronous operation mode, and detection is performed at a low inverter frequency. It is possible to set Ta shorter than the case.

  As described above, by detecting the open phase in the synchronous operation mode, even when the load is small, the d-axis current Id, q-axis by the predetermined d-axis current command value Id *, q-axis current command value Iq *. Since the current Iq flows, it is not erroneously detected as an open phase.

  If it is determined that even one phase is missing, the AC voltage output of the three-phase inverter is stopped because there is a possibility that the motor cannot be driven normally. By stopping, it is possible to prevent the problem of noise and the load on the specific output device of the three-phase inverter from increasing and leading to destruction.

  Further, by restarting the motor drive after the lapse of a predetermined time, it is possible to automatically continue the operation even when the phase loss is erroneously detected.

<Description of software processing flow>
An example of processing inside the microcomputer that implements the control unit 5 will be described with reference to the flowchart of FIG.

  FIG. 6 shows a flowchart for executing the phase loss detection process in the phase loss detection means of the present embodiment. This process is executed at a cycle in which the current value output from the current detection means is updated or at a constant cycle slower than that.

First, it is determined whether or not the operation mode is synchronous (step S1).
If it is not in the synchronous operation mode in this determination step S1, 0 is set to the U phase, V phase, and W phase missing phase detection counters Ku, Kv, and Kw (step S2). In the determination step S1, if it is in the synchronous operation mode, it is determined whether or not the absolute value | Iu | of the U-phase motor current Iu output from the current detection means exceeds the threshold value Ij (step S3). .

  In this determination step S3, if | Iu | does not exceed Ij, the U-phase missing phase detection counter Nu is incremented by one (step S4), and whether or not the incremented value is smaller than the determination value M. Determination is made (step S5). In determination step S3, if | Iu | exceeds Ij, Nu is set to 0 (step S6).

  In the determination step S5, if Nu is equal to or greater than M, it is determined that a phase loss has occurred, and processing for detecting a phase loss is performed (step S7). In step S7, operation stop, protection processing, and the like are performed.

  In the above-described processing for U phase (steps S3 to S6), if it is not determined that the phase is missing, V phase is determined to be missing. If V phase is not determined to be missing, Make a W phase loss judgment. Since the V-phase and W-phase missing phase determination processing (steps S8 to S11, S12 to S15) is the same as the U phase, the description thereof is omitted.

  A motor control apparatus according to a second embodiment of the present invention will be described with reference to FIG. The difference from the first embodiment is the configuration of the current detection means for obtaining the current (Iu, Iv, Iw) of each phase flowing through the motor.

  As shown in FIG. 7, the current detection means detects the current of each phase flowing through the motor using a current sensor (22a and 22b) such as a Hall CT at the wiring section to the motor. Although all three phases may be detected by the sensor, in this embodiment, the U-phase and W-phase currents (Iu, Iw) are detected by the sensor, and the V-phase current value is calculated from the detected two-phase current values. The detection current calculator 23 calculates. Expression (9) is an arithmetic expression for obtaining the V-phase current value Iv.

Iv = − (Iu + Iw) (9)
By detecting the current of each phase flowing through the motor at the wiring portion to the motor using a current sensor, the motor current can be detected constantly and reliably over a wide operating range.

  A motor control apparatus according to a third embodiment of the present invention will be described with reference to FIG. The difference from the second embodiment is the configuration of the current detection means for obtaining the current (Iu, Iv, Iw) of each phase flowing through the motor.

  As shown in FIG. 8, the current detection means converts the current flowing through the motor into the shunt resistors (24a, 24b) provided between the lower arm switching element of the inverter main circuit and the inverter DC bus. Detection is performed by the current detection circuit 8. As in the first embodiment, the current detection circuit 8 amplifies voltages at both ends of the shunt resistors (24a, 24b), for example, using operational amplifiers such as operational amplifiers. Since the subsequent steps are the same as those in the second embodiment, the description thereof is omitted.

  As described above, by detecting the current of each phase flowing through the motor from the current flowing through the shunt resistor provided between the lower arm switching element of the inverter main circuit and the inverter DC bus without using the Hall CT. The current can be detected at a lower cost than in the second embodiment. In addition, since the phase current can be detected if the switching element of the lower arm is on, the operating range in which the current can be detected is wider than that in the first embodiment.

A motor control apparatus according to a fourth embodiment of the present invention will be described with reference to FIG.
In this embodiment, as shown in FIG. 9, when it is determined that even one phase is missing, the missing phase detection means has detected the missing phase to the host controller 25 by serial communication, digital signal, analog signal or the like. To be notified. As a result, it is possible to recognize that the phase loss has been detected on the host control device 25 side and to take appropriate measures. Further, the notification of the phase loss detection to the outside of the motor control device may be an LED display, a display display, or the like. In this case, the user can recognize the cause of the motor stop and can take an appropriate measure.

A motor control apparatus according to a fifth embodiment will be described with reference to FIG.
In this embodiment, even in the sensorless operation mode, as shown in FIG. 10, the phase loss detection is performed when the d-axis current command value Id * and the q-axis current command value Iq * are larger than the predetermined values. The current command to be compared with the predetermined value is not limited to Id * and Iq *. For example, the current command I1 * obtained by combining Id * and Iq * may be compared with the predetermined value. The predetermined value may be the same or different depending on the current command to be compared.

  Further, in the sensorless operation mode, when it is expected that the state where Id * and Iq * do not exceed the predetermined value will continue, a current exceeding the predetermined value is periodically supplied to Id * periodically. Phase loss detection can be activated.

  As described above, even when the load is small in the sensorless operation mode, it is possible to detect the phase loss without erroneous detection. If phase loss detection can be performed in the sensorless operation mode, phase loss can be detected without waiting for the next activation when phase loss occurs during operation after the synchronous operation mode.

DESCRIPTION OF SYMBOLS 1 DC power supply 2 Inverter main circuit 3 Synchronous motor 4 Gate drive circuit 5 Control part 6 Current detection means 7 Shunt resistor 8 Current detection circuit 9 Motor current reproduction calculator 10 Phase loss detection means 11 Motor control part 12 Drive signal formation part 13 Voltage Command calculator 14 dq / 3φ converter 15 3φ / dq converter 16 First-order lag filter 17 Axis error calculator 18 Subtractor 19 PLL controller 20a, 20b Control changeover switch 21 Integrator 200 Mechanical load

Claims (14)

In a motor control device comprising a three-phase inverter that outputs a three-phase AC voltage for driving a synchronous motor, and a current detection means that detects a current flowing in each phase of the motor,
Equipped with a synchronous operation mode with a predetermined command value and an operation mode with position feedback,
A motor control apparatus comprising: a phase loss detection unit that detects a phase loss based on a current value detected by the current detection unit during the synchronous operation mode.   The motor control device according to claim 1, wherein the phase loss detection unit detects phase loss during a constant speed period provided in the synchronous operation mode.   2. The motor control device according to claim 1, wherein the phase loss detection unit detects phase loss during a predetermined period before switching from the synchronous operation mode to the operation mode based on the position feedback. 3. . In a motor control device comprising a three-phase inverter that outputs a three-phase AC voltage for driving a synchronous motor, and a current detection means that detects a current flowing in each phase of the motor,
When the current command value for calculating the command value of the three-phase AC voltage is larger than a predetermined value, the phase loss detecting means detects the phase loss based on the current value detected by the current detection means. Motor controller.   5. The motor control device according to claim 1, wherein the phase loss detection unit detects phase loss within a predetermined speed range. 6.   6. The motor control device according to claim 1, wherein the current detection means detects a current flowing in each phase of the motor from a current flowing in a shunt resistor of the inverter DC bus. Control device.   6. The motor control device according to claim 1, wherein the current detection unit is provided between a two-phase or three-phase lower arm switching element of the three phases of the inverter and the inverter DC bus negative side. A motor control device that detects a current flowing in each phase of a motor from a current flowing in a shunt resistor provided.   6. The motor control device according to claim 1, wherein the current detection unit detects a current flowing in each phase of the motor using a current sensor.   9. The motor control device according to claim 1, wherein the AC voltage output of the three-phase inverter is stopped when the phase loss is detected by the phase loss detection unit.   9. The motor control device according to claim 1, wherein the AC voltage output of the three-phase inverter is stopped when the phase loss detection unit determines that the phase loss is detected, and the motor drive is restarted after a predetermined time has elapsed. A motor control device that is activated.   The motor control device according to any one of claims 1 to 8, wherein a phase loss detection is notified to the outside of the motor control device when the phase loss detection means determines that a phase loss has occurred. .   The air blower using the motor control apparatus as described in any one of Claims 1-11.   The compressor drive device using the motor control apparatus as described in any one of Claims 1-11.   The pump using the motor control apparatus as described in any one of Claims 1-11.