Motor temperature estimator and motor controller

Abstract

A motor-current square value calculation section 45 calculates, as a motor-current square value, the sum of respective square values of two phase currents converted from three phase currents flowing through an electric motor. A temperature estimation calculation section 44 performs low-pass filtering for the motor-current square value, and calculates temperature increases of the mass portion and coils on the basis of the filtered motor-current square value. In the low-pass filtering, filtering calculation is performed in a manner which changes depending on rotational speed RV of the electric motor; i.e., whether the electric motor is in a rotating state or in a stopped state. The temperature increase of the mass portion is added to ambient temperature of the electric motor to thereby estimate temperature of the mass portion, and the temperature increase of the coils is added to the estimated temperature of the mass portion to thereby estimate temperature of the coils. Accordingly, the coil temperature of the electric motor can be accurately detected, and current flowing through the electric motor is properly controlled in accordance with the detected temperature.

Description

technical field [0001] The present invention relates to a motor temperature estimating device for estimating (estimating) the temperature of a case, stator, winding (coil) or the like of an electric motor (motor), and a method based on the temperature estimated by the motor temperature estimating device A motor control device that limits the current flowing through the motor by controlling the winding temperature of the motor. technical background [0002] As shown in Japanese Patent Application Laid-Open (kokai) No. H10-67335, the conventional device includes a temperature sensor provided in the motor, and corrects the drive current based on the temperature detected by the temperature sensor to compensate The resulting decrease in the magnetic permeability of the motor stator. Also, in this publication, a technique for estimating the motor temperature by integrating the drive current flowing through the motor is proposed. [0003] The above technique of using a temperatur...

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Problems solved by technology

[0003] The above technique of using a temperature sensor incorporated in the motor is not preferred in view of the cost and ease of mounting the motor to a device using the motor, since the temperature sensor and the means for connecting the temperature sensor must be provided. Connecting wires to the control circuit of the motor

Although the above-mentioned patent publication proposes a technique of estimating the temperature of the motor by integrating the drive current flowing through the motor, it does not elaborate on the technique

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