JP2004318709A - Motor control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain accurate torque or the like by recognizing a change in temperature and correcting a gain and a constant used in a monitor by the temperature. <P>SOLUTION: In a motor control method for controlling a motor on the basis of a supplied command, heat radiation from the motor is estimated (S1), a temperature rise is obtained on the basis of the heat radiation (S2), and a resistance value and a torque constant are corrected on the basis of the temperature rise (S3). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for correcting a motor torque constant, a resistance, and the like from a motor temperature or estimating a motor temperature, and outputting an accurate torque.
[0002]
[Prior art]
Conventionally, the motor is controlled by feeding back a detected current by a current amplifier as shown in FIG. In the case of the torque command, the current is controlled by being converted into a current command and input. This was converted into a voltage command to control the motor by switching the power transistor.
Further, the motor is protected by estimating the temperature by using a state observer using a thermal model of the motor (Japanese Patent Application Laid-Open No. H11-163,837).
[0003]
[Patent Document 1]
JP-A-6-54572
[Problems to be solved by the invention]
However, in the prior art, when the torque constant of the motor changes with the temperature, the motor torque changes, so that there is a problem that normal control cannot be performed, the actual control does not match, and monitoring cannot be performed.
Therefore, an object of the present invention is to obtain a correct torque or the like by knowing a change in the temperature in a motor and correcting a gain or a constant used in a monitor with the temperature of the motor.
[0005]
[Means for Solving the Problems]
In order to solve the above problem, the present invention is configured as follows.
The motor control method according to claim 1 of the present invention is a motor control method for controlling a motor based on a given command, wherein a heat radiation amount from the motor is obtained, and a temperature rise amount is obtained based on the heat radiation amount. It is characterized in that the resistance value and the torque constant are corrected based on the temperature rise.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
The flow of the present invention will be described with reference to FIG. In S1 of FIG. 4, the heat radiation is estimated. In S2, a temperature rise is obtained from the obtained heat radiation. In S3, the resistance value and the torque constant are corrected based on the temperature rise.
A specific embodiment of the present invention will be described with reference to FIG.
In FIG. 1, 1 is a microcomputer, 2 is a PWM conversion circuit, 3 is a base drive circuit, and 4 is a power transistor module. The operation of the circuit configured as described above will be described with reference to the speed control block of FIG. First, commands such as speed and position are received from outside. For example, in the case of a speed command, the speed control is performed, and the output current command drives the power transistor 4 through the base drive circuit with the output of the current control to control the motor. Then, the microcomputer 1 observes the temperature of the motor 5 or subtracts the heat radiation amount from the current flowing through the motor 5 (for example, overload situation) to estimate the approximate temperature. For the observation, for example, the temperature is electrically measured by a temperature sensor attached to the motor. The method of estimating the temperature of the motor 5 is calculated by, for example, the following equation.
Power component P = i ² R-heat radiation component i: Current temperature rise dθ = P / Rt Rt: Thermal resistance heat radiation component can be measured in advance or estimated from motor 5 or motor heat sink. The thermal resistance is measured beforehand when a certain thermal energy is applied, and is stored in a microcomputer or the like. Thus, the resistance and inductance of the motor, the torque constant Kt, and the like are corrected.
For example, the resistance R of the motor is calculated as follows.
[0007]
R = R0 + ΔRdθ (1)
R0: resistance value at reference temperature ΔR: temperature coefficient dθ: temperature rise
Kt = Kt0 + ΔKtdθ (2)
Kt0: torque constant at reference temperature ΔKt: temperature coefficient The reference temperature and the temperature coefficient are measured in advance and stored in the microcomputer 1 or the like. Conversely, the reference temperature may be measured from a resistance or the like. Thus, the gain G of the current amplifier is calculated by the following equation to correct the current amplifier.
[0009]
G = Kd * G (s) / (R + sL + KdG (s)) (3)
Kd: current detection gain G (s): power section gain FIG. 2 is a block diagram showing this speed control. Since the torque constant is found to affect the speed control, it is recalculated. FIG. 3 is a block diagram of a current amplifier. In a current amplifier, it is determined by a current detection gain, a power section gain, a motor resistance, and an inductance.
[0010]
【The invention's effect】
As described above, according to the present invention, since the correction can be made by estimating the motor temperature or the temperature, the accuracy of the control gain and torque of the control loop can be obtained. In particular, it is effective for a permanent magnet type synchronous motor.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a block diagram of a speed control of the present invention. FIG. 3 is a block diagram of a current amplifier of the present invention. FIG. 4 is a control flow of the present invention.
1: microcomputer 2: PWM conversion circuit 3: base drive circuit 4: power transistor module 6: motor

Claims (4)

In a motor control method for controlling a motor based on a given command,
Determine the temperature of the motor,
Estimating the heat radiation from the motor,
Determine the temperature rise based on the heat radiation,
A motor control method comprising correcting control parameters such as a resistance value and a torque constant based on the temperature rise. 2. The motor control method according to claim 1, wherein the temperature rise is obtained by subtracting a heat radiation from a power of the motor. 2. The motor control method according to claim 1, wherein the temperature coefficient is stored in advance from a heat sink or the like of the motor. 2. The motor control method according to claim 1, wherein the motor temperature is estimated from the temperature of the power conversion unit heat sink of the control device.

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