JP2010081664A - Motor control unit and air conditioner using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect phase interruption of a motor with a simple and low-cost circuit configuration in a motor control unit. <P>SOLUTION: The motor control unit is provided with: a current abnormality determining means 17 that compares the maximum value of the current value of a motor 4, detected by a current detecting means 6, during a predetermined time equal to or longer than a rotation period with a current reference value 18 to determine an abnormality in rotation; a number-of-rotations abnormality determining means 11 that compares the average value of the number of rotations estimated by a number-of-rotations estimating means 8 for a predetermined time with a number-of-rotations reference value 12 to determine an abnormality in the number of rotations of the motor 4; a rotation abnormality determining means 19 that, when an abnormality is determined by at least either of the current abnormality determining means 17 and the number-of-rotations abnormality determining means 11, determines an abnormality in the rotation of the motor 4; and a protective operation means 14 that, when a rotation abnormality is determined by the rotation abnormality determining means 19, stops the operation of the motor 4. When a third predetermined time has passed after start of the motor 4 and then rotation abnormality determination by the rotation abnormality determining means 19 lasts for a fourth predetermined time, an open phase of the motor 4 is determined and the operation of the motor 4 is stopped. <P>COPYRIGHT: (C)2010,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. It is transmitted to the user that the phase failure is abnormal (see, for example, Patent Document 2).

  FIG. 4 is a block diagram showing the configuration of a conventional motor control device described in Patent Document 1. As shown in FIG. As shown in FIG. 4, 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 detection means 11 determines that the rotation speed is 12 or less during the drive, and the rotation speed estimated by the rotation speed estimation means 8 is less than the reference rotation speed 12 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 missing, the phase failure abnormality LED 16 is turned on to notify the user that the phase loss is abnormal.
JP 2005-192271 A JP 2005-253196 A

  However, since the conventional configuration detects a phase loss only by the number of rotations of the motor, there is a problem that even in the phase loss state, the motor rotates at a light load and the phase loss cannot be detected reliably. 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 an electric motor control device that can detect an open phase with high accuracy by using two parameters of rotation speed and current even when the electric current of the electric motor cannot be correctly estimated due to noise or the like.

  In order to solve the above-described conventional problems, the motor control device of the present invention detects the current value flowing in the winding of the motor by the current detection means, and after a predetermined time has elapsed from the start, the rotation of the motor in a phase with the motor When the state where the maximum value of the current value at a predetermined time that is equal to or greater than the period continues below the reference value is continued for a predetermined time, or when the state where the average value of the motor rotation speed at a predetermined time is other than the reference value continues for a predetermined time A phase determination is performed, and when a phase failure occurs, a function for applying a protective operation to the motor is provided.

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

  The electric motor control device of the present invention, when a predetermined time elapses from the start, when the maximum value of the current value at a predetermined time equal to or greater than the rotation cycle of the electric motor of a certain phase of the electric motor is continuously below the reference value for a predetermined time, or When the average value of the rotation speed of the motor is continuously outside the reference range for a predetermined time, the motor phase loss determination is performed, and when the motor is in the phase loss state, by stopping the operation of the motor, It is possible to realize a motor control device having a circuit configuration that is simple, low-cost, and free from erroneous detection without using a complicated circuit.

  According to a first aspect of the present invention, a current of a certain phase of the motor detected by the current detection unit, a current abnormality determination unit that compares the detected current value with a current reference value, and a current of the motor detected by the current detection unit Estimated by the induced voltage estimating means for estimating the induced voltage by the value and DC voltage detecting means and the PWM signal generating means, the rotational speed estimating means for estimating the rotational speed of the motor by the induced voltage estimating means, and the rotational speed estimating means A rotational speed abnormality determining means for comparing the rotational speed with a rotational speed reference value; and determining a rotational abnormality of the electric motor when it is determined abnormal by at least one of the current abnormality determining means and the rotational speed abnormality determining means. A rotation abnormality determining means for performing the operation, and a protection operation means for stopping the operation of the electric motor. When the maximum current value in a predetermined time of a certain phase of the motor is determined to be equal to or less than a reference value while the motor is being driven, and the maximum current value by the current detection unit continues below the reference value for a predetermined time, an abnormal current is detected. When a predetermined time has elapsed since the start of the motor, or when an average value of the rotation speed estimated by the rotation speed estimation means for a predetermined time is compared with a rotation speed reference value, and an abnormality in the rotation speed of the motor is determined. The rotation abnormality determining means determines that the rotation is abnormal, and the protection operation means sends the motor stop command to the PWM signal generating means to stop the operation of the motor.

  Thus, the electronic control device having a circuit configuration that is simple, low-cost, and free from false detection without using a complicated circuit, by comparing and determining the maximum current value in a predetermined time of a phase of the motor with a reference value Can be realized.

  In addition, even if the motor rotates abnormally due to a light load in the phase loss state, a current failure does not flow in the phase that has lost phase, so that the phase loss can be detected. Further, even when the microcomputer erroneously recognizes that a current is flowing in the phase that is missing, it is possible to reliably detect the missing phase by comparing and determining the rotational speed of the motor and the reference value.

  According to a second aspect of the invention, in particular, in the first aspect of the invention, the maximum value of the current value of a certain phase of the motor detected by the current detection means at a predetermined time equal to or greater than the rotation period of the motor continues for a predetermined time or less. In this case, it is determined that the motor is out of phase only, and erroneous detection of the phase loss is prevented by performing a rotational speed abnormality determination after a time equal to or longer than the time when the motor reaches the rotational speed reference value when the motor is normal. It becomes possible.

  According to a third aspect of the invention, in the first or second aspect of the invention, in the first or second aspect of the invention, when the rotation abnormality determining unit determines that the phase is lost, the protective operation unit stops the motor operation. After the motor is stopped, the motor is restarted after a predetermined time has elapsed, and when the operation of stopping the motor by the protective operation means continues for a predetermined number of times, a motor start instruction from the user is issued. By not restarting the motor as long as there is no, it is possible to more reliably prevent the motor from being stopped due to erroneous detection, prevent problems that occur when the motor continues to operate as it is, and the user again Since the abnormal operation can be confirmed by operating the electric motor, it is possible to smoothly deal with repairs at the time of phase loss.

According to a fourth aspect of the present invention, in particular, in any one of the first to third aspects, when the motor operation is stopped by the protection operation means and the motor start instruction is received from the user, By setting the target rotational speed to a value equal to or lower than that during normal operation, abnormal heat generation of the motor can be reduced when the motor rotates abnormally due to phase loss.

  According to a fifth aspect of the present invention, in particular, in any one of the first to fourth aspects, when the motor determines that the phase is out of phase and stops operating, and then receives an abnormality determination transmission instruction from the user, an abnormality is detected with the 7-segment LED. By transmitting to the user that a phase failure has occurred by means of a code or the like, it is possible to smoothly cope with a phase failure without transmitting an abnormality that is more than necessary.

  In a sixth aspect of the present invention, the motor control device according to any one of the first to fifth aspects 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 control unit 15 is usually configured using a microcomputer (not shown), and is detected from the current of the motor 4 detected by the current detection unit 6, the output voltage calculated by the PWM signal generation unit 13, and the DC voltage detection unit 5. The induced voltage of the electric motor 4 is estimated by the induced voltage estimating means 7 from the DC voltage to be detected, and the rotational speed estimating means 8 detects the rotational speed of the electric motor 4 from the estimated induced voltage. 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 a normal open phase state, the phase current of the phase that has been lost since the start of the motor 4 continues to be below a predetermined value, so the maximum current value in a predetermined time that is greater than or equal to the rotation period of the motor 4 detected by the current detection means 6. Current abnormality determining means 17 for comparing the current value with the current reference value 18, and comparing the average value of the rotational speed estimated by the rotational speed estimating means 8 with the rotational speed reference value 12 for comparing the rotational speed estimated value with the rotational speed reference value 12. A rotation abnormality determination means 11 for determining, a rotation abnormality determination means 19 for determining a rotation abnormality of the electric motor 4 when at least one of the current abnormality determination means 17 and the rotation speed abnormality determination means 11 determines an abnormality; 4 is stopped, the maximum value of the phase current value during the driving of the motor 4 during a predetermined time equal to or greater than the rotation cycle of the motor is determined to be equal to or less than the current reference value 18 and The average value of the rotation speed estimated by the rotation speed estimation means 8 when the maximum value of the current value by the current detection means 6 continues for a predetermined time at a predetermined time longer than the rotation cycle of the electric motor 4 for a predetermined time. If the motor 4 is outside the range of the rotation speed reference value 12 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.

When the maximum current value of a phase of the motor 4 is detected by the current detection means 6, the motor 4 is driven by torque control or the like shown in FIG. 3 after elapse of more than the time that the motor 4 reaches the rotation speed reference value 12 during normal operation. Even when the phase current waveform of the motor is an unbalanced waveform, the maximum value of the current value of a certain phase of the motor 4 detected by the current detection means 6 at a predetermined time longer than the rotation period of the motor 4 is less than the reference value. It is determined that the current is abnormal when it continues for a predetermined time, and it is determined that the rotational speed is abnormal when the average value of the rotational speed estimated by the rotational speed estimation means 8 continues outside the range of the rotational speed reference value 12 for a predetermined time. By doing so, it is possible to prevent erroneous detection of phase loss.

  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 4 unless there is an instruction to start the motor from the person, it is possible to more reliably prevent the motor from being stopped due to erroneous detection, and to prevent problems that occur when the motor 4 continues to operate as it is. Furthermore, the user can operate the electric motor 4 again to check the abnormal operation. When the electric motor 4 is operated again, the abnormal rotation of the electric motor is reduced by setting the target rotational speed of the electric motor 4 to a value equal to or lower than that during normal operation. This makes it possible to obtain a more reliable motor control device.

(Embodiment 2)
FIG. 2 is a block diagram showing the configuration of the motor control apparatus according to Embodiment 2 of the present invention. If it is determined that the phase is missing under the above conditions, the 7-segment LED display unit 20 indicates that there is a phase failure when an abnormality determination transmission instruction is received from the user using a remote controller (not shown) or the like. It is an electric motor control device characterized by notifying that it is a failure but also notifying the contents of the failure by sending it to the user, and sending the abnormality to the user when necessary. Since it is the same as that of Embodiment 1, the description thereof is omitted.

  As described above, in the present embodiment, it is possible to more reliably prevent the motor 4 from being stopped due to erroneous detection, to prevent problems that occur when the motor 4 continues to operate as it is, and to deal with a phase failure abnormality. Can be performed smoothly.

  As described above, the motor control device according to the present invention can surely detect the phase failure of the motor, and thus can be widely applied to all control devices that drive and control the motor.

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 The figure which shows the phase current waveform of the unbalanced motor by torque control etc. 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 Rotation speed reference value 13 PWM signal Generation means 14 Protective operation means 15 Control unit 16 Phase failure abnormality LED
17 Current abnormality determination means 18 Current reference value 19 Rotation abnormality determination means 20 7-segment LED display section

Claims (6)

A current detection means for detecting a current flowing in each winding of the motor, and a current value detected by the current detection means are compared with a maximum value at a first predetermined time and a predetermined current reference value to determine a current abnormality of the motor. Current abnormality determination means for performing, current value of the motor detected by the current detection means, DC voltage detection means, induced voltage estimation means for estimating the induced voltage by PWM signal generation means, and the motor by the induced voltage estimation means A rotation speed estimation means for estimating the rotation speed of the motor, and an average value of the rotation speed estimated by the rotation speed estimation means for a second predetermined time and a rotation speed reference value to compare the rotation speed and determine a rotation speed abnormality of the motor A rotation abnormality of the motor is determined when at least one of the number abnormality determination means, the current abnormality determination means, and the rotation speed abnormality determination means determines an abnormality. Rotation abnormality determining means, and a protective operation means for stopping the operation of the electric motor when the rotation abnormality determining means determines that the rotation abnormality is present, and after the third predetermined time has elapsed since the start of the motor, the rotation abnormality determining means An electric motor control device characterized in that, when the rotation abnormality determination by is continued for a fourth predetermined time, it is determined that the electric motor is out of phase and the operation of the electric motor is stopped. The first predetermined time described in the previous paragraph is set to a time longer than the rotation cycle of the motor, and the third predetermined time described in the previous paragraph is a time longer than the time for the motor to reach the rotation speed reference value when it is normal. The motor control device according to claim 1. After the motor is stopped by the protective operation means, the motor is restarted after a lapse of a fifth 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 3. The motor control device according to claim 1, wherein the motor control device is not restarted unless there is an instruction to start the motor. After stopping the motor with the protective operation means, when receiving a motor start instruction from the user, the target rotational speed of the motor at the time of restart is set to a value below normal operation, The electric motor control device according to any one of claims 1 to 3. After the motor is determined to be in phase failure and operation is stopped, when an abnormality determination transmission instruction is received from the user, a 7-segment (hereinafter referred to as 7-segment) LED display section notifies the user that a phase failure has occurred. The motor control device according to any one of claims 1 to 4, wherein An air conditioner using the motor control device according to any one of claims 1 to 5.

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