JP2012222950A - Compressor motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve such a problem that a state where an estimation error of rotation speed and position estimation operation becomes excessive is generated due to speed variation to torque pulsation.SOLUTION: A compressor motor control device has a current command corrector storing a speed compensation value in the case where a rotation speed becomes lower than a limit minimum speed at each of a plurality of positions in predetermined one rotation, and correcting a current command at the plurality of positions by using the stored speed compensation storing value. Speed compensation is performed so that the rotation speed does not become lower than the limit minimum speed. Thereby, influences of a high harmonic wave are suppressed, and stable driving can be realized.

Description

  The present invention relates to an inverter control device that drives a compressor motor without a position encoder.

  Conventionally, as this type of technology, for example, a harmonic component of an induced voltage of a compressor motor is modeled to suppress an estimation error of the rotor position and speed (for example, see Non-Patent Document 1).

1996 IEEJ National Conference 4-280,281 “Harmonic Speed Electromotive Force Compensation in Sensorless Salient-Pole Brushless DC Motor”

However, the conventional compensation method in the previous period has a problem that the calculation amount increases due to modeling of harmonic components, and a high-performance arithmetic unit is required.
The present invention solves the above-described conventional problems. By changing at least one response frequency of the estimation calculation, the current control, and the speed control control operation according to the rotation speed, the response to the fundamental wave component and the harmonics are changed. An object of the present invention is to provide a compressor motor control device that suppresses the influence of harmonics by always maintaining an attenuation ratio of a certain level or higher with respect to the response to the wave component.

  In order to solve the above-described conventional problems, a compressor motor control device according to the present invention includes a gain calculator that changes a gain according to the number of rotations of a compressor motor. At least one type of gain calculator is provided, and the compressor motor is driven while changing the gain of each controller so that the response to the fundamental component and the response to the harmonic component during operation always have a certain damping ratio or more. .

  The compressor motor control device of the present invention is configured so that the response to the fundamental wave component and the response to the harmonic component always have a certain damping ratio or more even when the induced voltage of the compressor motor includes harmonics. By driving while changing the gain of the controller, it is possible to provide a compressor motor control device that can suppress the influence of harmonics and obtain a stable drive.

The block diagram of the compressor motor control apparatus in Embodiment 1 of this invention. Block diagram of the speed controller in Embodiment 1 of the present invention

The compressor motor control device of the present invention detects a motor that rotates and drives a compressor, an inverter circuit that applies a pulse width modulation to a voltage supplied from a DC power source, and applies the motor to the motor. A motor current detector, a DC voltage detector for detecting a DC voltage supplied to the inverter circuit, a position speed estimator for detecting the estimated rotational position and estimated speed of the electric motor, and a rotational speed command given from the outside A speed controller that calculates a current command by comparing the current command with the estimated rotational speed, a current controller that calculates a voltage command by comparing the current command and the motor current, the voltage command and the DC voltage A PWM signal generator that generates a PWM signal from the drive circuit and drives the inverter circuit. Of the speed controller, the current controller, and the position speed estimator, Kutomo One is, harmonic components included in the induced voltage of the motor changes the control gain in response to said estimated rotation speed to attenuate than the fundamental wave.

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

(Embodiment 1)
FIG. 1 is a block diagram of a compressor motor control apparatus according to an embodiment of the present invention.

  In FIG. 1, a motor 2 that drives a compressor 1 is connected to an inverter circuit 3, and a phase current is detected as I3 by a current detection circuit 4. Further, the inverter circuit 3 is connected to a DC power source 5, and the DC voltage is detected as VD by the voltage detection circuit 6. Next, the control circuit 7 that controls the speed of the motor 2 includes a speed controller 8 that outputs a current command Ic from an externally set speed command ωs and an estimated motor speed ω, and a current command Ic and a phase current I3. A current controller 9 that outputs a phase voltage command V3 based on the estimated rotational position θ, a PWM signal generator 10 that generates a drive signal SW of the inverter circuit 3 by pulse-width modulating the phase voltage command V3, and electrical characteristics of the motor And a position / speed estimator 11 that outputs an estimated rotational position θ and an estimated speed ω from the phase current and applied voltage.

  In order to simplify the explanation, the motor 2 is assumed to be a two-pole motor and the induced voltage has a sixth harmonic.

  Next, FIG. 2 is a detailed block diagram of the speed controller 8.

  In FIG. 2, the speed controller 8 outputs a current command Ic by PI control calculation from the difference between the command speed ωs and the estimated speed ω. The speed control gain changing means 12 changes the proportional gain Kp and the integral gain Ki so that the cut frequency ωc of the response characteristic of the PI control calculation becomes equal to ω.

  Here, since the PI control calculation is a general method, detailed description is omitted because it is known.

  Next, the current controller 9 and the position / speed estimator 11 are different in control calculation, but the detailed description thereof is omitted because the gain changing method is the same as the speed control gain changing means 12.

  Various methods have already been put into practical use for the PWM signal generator 10 and will not be described in detail because they are known.

  In this embodiment, CT is used to detect the phase current of the motor, but the effect is not changed even if the current is detected by a shunt resistor provided in the DC section.

  As described above, the compressor motor control device according to the present invention performs the speed compensation so that the rotational speed does not fall below the minimum minimum rotational speed, thereby stabilizing the compressor motor that detects the rotational speed and the rotational position by estimation calculation. Therefore, it can be applied to various compressor motor control devices.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Motor 3 Inverter circuit 4 Current detection circuit 5 DC power supply 6 Voltage detection circuit 7 Control circuit 8 Speed controller 9 Current controller 10 PWM signal generator 11 Position speed estimator 12 Speed control gain change means

Claims (1)

An electric motor that rotates the compressor, an inverter circuit that applies a pulse width modulation to a voltage supplied from a DC power source and applies the electric motor, a motor current detector that detects a motor current flowing through the electric motor, and an inverter circuit A DC voltage detector for detecting a DC voltage to be detected, a position speed estimator for detecting an estimated rotational position and an estimated speed of the electric motor, and a rotational speed command given from outside and the estimated rotational speed are compared. A speed controller that calculates a current command; a current controller that calculates a voltage command by comparing the current command and the motor current; and a PWM signal that is generated from the voltage command and the DC voltage, and the inverter circuit And at least one of the speed controller, the current controller, and the position speed estimator is the motor. Harmonic component contained in the induced voltage compressor motor control device and changes the control gain in accordance with the estimated rotational speed to attenuate than the fundamental wave.

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