JP2009142004A - Motor controller and air conditioner using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the open phase of a motor in simple and low-cost circuit constitution. <P>SOLUTION: This motor controller is constituted of a microcomputer which includes a current detecting means 6 for a motor 4, a rotation abnormality determining means 18, which compares a current value detected by the current detecting means 6 and a current reference value 12 thereby determining an abnormality in rotation, and a protective operation means 14, which stops the operation of the motor 4 when it determines an abnormality in rotation by the above rotation abnormality determining means 11. In case that the determination of abnormality in rotation by the rotation abnormality determining means 18 has continued for a second specified time after passage of a first specified time since start of the motor 4, it is possible to stop the operation of the motor 4, determining it to be open phase of the motor 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor control device for a compressor used in an air conditioner.

  Conventionally, the motor control device of this type of compressor estimates the rotation speed of the compressor, and when the rotation speed is below a reference value for a predetermined time, it is determined that the motor is out of phase, and the motor operation is stopped. The user is informed that the phase failure is abnormal (see, for example, Patent Document 1).

  FIG. 3 is a block diagram showing a configuration of a conventional electric motor control device described in Patent Document 1. As shown in FIG. As shown in FIG. 3, the converter 4 converts the AC power source 1 into a DC voltage and applies it to the inverter 3 to drive the electric motor 4. The induced voltage of the motor 4 is estimated by the induced voltage estimating means 7 from the current of the motor 4 detected by the current detecting means 6, the output voltage detected from the PWM signal generating means 13, and the DC voltage detected from the DC voltage detecting means 5. Then, the rotational speed estimation means 8 detects the rotational speed of the electric motor 4 from the estimated induced voltage.

  After the elapse of a predetermined time from the start, the rotation speed abnormality detecting means 11 determines that the rotation speed is the reference rotation speed 1 or less during driving, and the rotation speed estimation means 8 determines that the rotation speed is the reference rotation speed 12 or less for a predetermined time. If it continues, it is determined that the motor 4 is out of phase, and the protection operation means 14 sends a motor stop command to the PWM signal generation means 13 to stop the operation of the motor 4.

Further, if it is determined that the phase is out of phase, the phase loss abnormality LED 16 is turned on to notify the user that the phase loss is abnormal.
JP 2005-253196 A

  However, in the conventional configuration, since the phase loss is detected from the rotation speed of the motor, the motor rotates at a light load even in the phase loss state, and there is a problem that the phase loss cannot be reliably detected. It was.

  The present invention solves the above-described conventional problems, and even when the motor rotates in the phase-open state, the phase loss is reliably detected, and even when the phase current of the motor such as torque control is unbalanced, an error occurs. An object of the present invention is to provide a motor control device that does not detect.

  In order to solve the above-described conventional problems, an electric motor control device according to the present invention detects a current value flowing in each winding of an electric motor by a current detection unit without obtaining a rotation speed of the electric motor, and includes a microcomputer included in the control device. Use the motor when the phase current value of a certain phase of the motor continues to be below the reference value for a predetermined period of time after starting. Has a function to call.

  As a result, when the electric motor is in an open phase state, the operation of the electric motor is surely stopped.

The motor control device according to the present invention uses the microcomputer included in the control device to determine the motor phase loss when the current value of a certain phase of the motor is continuously below the reference value for a predetermined time after a predetermined time has elapsed since the start. Thus, when the motor is in an open phase state, by stopping the operation of the motor, a motor control device having a circuit configuration that is simple, low-cost, and free from false detection without using a complicated circuit. Can be realized.

  The first aspect of the invention includes a phase abnormality of the motor detected by the current detection unit, a rotation abnormality determination unit that compares the detected current value with a current reference value, and a protection operation unit that stops the operation of the motor. After a predetermined time has elapsed since the start of the motor, the rotation abnormality determination means determines that the current value of a phase of the motor is not more than a reference value during driving of the motor, and the current value by the current detection means does not exceed the reference value If it continues for a predetermined time, it is determined that the motor is out of phase, and the motor operation is stopped by sending a motor stop command to the PWM signal generating unit by the protection operation unit. By using a microcomputer to compare and determine the current value of a phase of a motor with a reference value, it is possible to realize an electronic control device having a simple, low-cost, and no erroneous detection without using a complicated circuit. . In addition, even if the motor rotates due to a light load in the phase loss state, current does not flow in the phase that has lost phase, so the phase loss can be detected reliably. In addition, even when the phase current waveform of the motor becomes unbalanced as in torque control, only when the current value of a phase of the motor detected by the current detection means continues below a reference value for a predetermined time. By determining that the motor is out of phase, it is possible to prevent erroneous detection of the out of phase.

  According to a second aspect of the present invention, when a predetermined time has elapsed since the start of the motor, a determination is made when the rotation abnormality determination means determines that the current value of a phase of the motor is below a reference value and for a predetermined time while the motor is being driven. A motor control device that stops the motor operation by the protection operation means when the phase is determined, and after the motor is stopped by the protection operation means, the motor is restarted after a lapse of a predetermined time, and the protection operation means When the operation to stop the motor continues for a predetermined number of times, the motor is not restarted unless the motor start instruction is received from the user, thereby preventing the motor from stopping due to false detection more reliably. It is possible to prevent problems that may occur when the operation is continued, and to allow the user to operate the motor again and check for abnormal operation, so that repairs in the event of a phase failure can be performed smoothly. It is possible.

  According to a third aspect of the present invention, when an abnormality determination transmission instruction from the user is input to the microcomputer after the motor is determined to be in a phase failure and the operation is stopped, the fact that the phase failure is abnormal is transmitted to the user. Therefore, it is possible to smoothly cope with a phase loss abnormality without transmitting an abnormality that is more than necessary.

  According to a fourth aspect of the invention, the motor control device according to the first to third aspects of the invention is used in an air conditioner, and the effects of the respective motor control devices can be exhibited.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram showing the configuration of the motor control device according to the first embodiment of the present invention.

  In FIG. 1, a converter 2 converts an AC power source 1 into a DC voltage and applies it to an inverter 3. The DC voltage applied to the inverter 3 is converted into a three-phase pseudo AC by a circuit such as a switching element in the inverter 3. It is converted into a voltage, and thereby the electric motor 4 is driven.

The controller 15 induces an induced voltage of the electric motor 4 from the electric current of the electric motor 4 detected by the electric current detecting means 6, the output voltage calculated by the PWM signal generating means 13, and the DC voltage detected from the DC voltage detecting means 5. The rotational speed of the electric motor 4 is detected by the rotational speed estimating means 8 from the induced voltage estimated by the voltage estimating means 7 and further estimated. The PWM signal generation means 13 determines a command speed from the detected rotation speed 9 estimated by the rotation speed estimation means 8 and the target rotation speed 10 using a proportional integration calculation, and controls the inverter 3 based on the determined command speed. Is output.

  In the open phase state, the phase current of the phase that has been lost since the start of the motor continues below a predetermined value. Therefore, the rotation abnormality determination unit that determines the current value detected by the current detection unit 6 and compares it with the current reference value 17. 18 and a protection operation means 14 for stopping the operation of the electric motor 4, the phase current value is determined to be equal to or less than the current reference value 17 while the electric motor 4 is being driven, and the current value by the current detection means 6 is equal to or less than the reference value 17. If it continues for a predetermined time, it is determined that the motor 4 is out of phase, and a motor stop command is sent from the protection operation means 14 to the PWM signal generation means 13 to stop the operation of the motor 4.

  Furthermore, after the motor 4 is stopped by the protection operation means 14, the motor 4 is restarted after a predetermined time has elapsed, and the operation to stop the motor 4 by the protection operation means 14 continues for a predetermined number of times. By not restarting the motor unless there is a motor start instruction from the user, it is possible to more reliably prevent the motor from stopping due to a false detection, and to prevent problems that may occur if the motor continues to operate as it is. A person can operate the electric motor again to confirm abnormal operation, and a more reliable electric motor control device can be obtained.

(Embodiment 2)
FIG. 2 is a block diagram showing the configuration of the motor control apparatus according to Embodiment 2 of the present invention. When it is determined that the phase is missing under the above conditions, when the abnormality determination transmission instruction from the user is input to the microcomputer, the 7-segment LED display unit 19 indicates that the phase is abnormal. The motor control device is characterized in that an abnormality is transmitted to the user when necessary, and the other configuration and operation are the same as those in the first embodiment, and thus the description thereof is omitted.

  As described above, according to the present embodiment, it is possible to more reliably prevent the motor from being stopped due to erroneous detection, prevent problems that may occur when the motor continues to operate as it is, and smoothly respond to a phase loss abnormality. Can be performed.

  As described above, since the motor control device according to the present invention can detect the motor phase loss without erroneous detection, it can be widely applied to all control devices that drive and control the motor other than the air conditioner.

Configuration block diagram of electric motor control apparatus in Embodiment 1 of the present invention Configuration block diagram of an electric motor control device in Embodiment 2 of the present invention Block diagram of a conventional motor control device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Converter 3 Inverter 4 Electric motor 5 DC voltage detection means 6 Current detection means 7 Induced voltage estimation means 8 Rotation speed estimation means 9 Detected rotation speed 10 Target rotation speed 11 Rotation speed abnormality determination means 12 Current reference value 13 PWM signal generation Means 14 Protection operation means 15 Control unit 16 Phase failure abnormality LED
17 Current reference value 18 Rotation abnormality determination means 19 7-segment LED display

Claims (4)

Current detection means for detecting current flowing in each winding of the motor, rotation abnormality determination means for comparing the current value detected by the current detection means with a predetermined current reference value to determine rotation abnormality of the motor, and the rotation When the abnormality determination means determines that the rotation is abnormal, the microcomputer is provided with a protection operation means for stopping the operation of the motor, and after the first predetermined time has elapsed since the start of the motor, the rotation abnormality determination by the rotation abnormality determination means When the motor continues for the second predetermined time, it is determined that the motor is out of phase, and the motor operation is stopped. After the motor is stopped by the protective operation means, the motor is restarted after a lapse of a third predetermined time, and when the operation of stopping the electric motor by the protective operation means continues for a predetermined number of times, the user 2. The motor control device according to claim 1, wherein the motor is not restarted unless there is an instruction to start the motor. After the motor is judged to be in phase failure and the operation is stopped, when an abnormality determination transmission instruction is input from the user to the microcomputer, the 7-segment LED display unit transmits that the phase is abnormal. The electric motor control device according to claim 1, wherein the electric motor control device is characterized. An air conditioner using the motor control device according to any one of claims 1 to 3.

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