JP2004357476A - Motor drive circuit, method for driving motor, and program for driving motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure current detection accuracy and to realize accurate correction of the offset voltage of a drive current detecting system, in a state with the increase in cost being suppressed in a motor drive circuit. <P>SOLUTION: Temperature characteristics of the offset voltage are calculated, and the offset voltage is corrected by the calculated result, based on related information in the motor drive circuit and offset voltage information of current detecting means for detecting the drive voltage from an inverter circuit by using control means, such as a microcomputer provided originally in the motor drive circuit. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor driving technique for detecting a driving current from an inverter circuit and driving a motor by feedback control.
[0002]
[Prior art]
As a conventional technique related to the present invention, there is one described in Japanese Patent Application Laid-Open No. 2002-207052 (Patent Document 1). This publication discloses an offset canceling circuit composed of a non-linear circuit presenting a dead zone in an electric circuit near a zero cross in order to cancel a temperature drift of an offset of a magnetoelectric conversion element or an amplifier for amplifying the output of the current detector. The configuration provided is described.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-207052
[Problems to be solved by the invention]
In the above prior art, it is necessary to provide an offset canceling circuit that presents a dead zone in an electric circuit near the zero cross.
An object of the present invention is to provide a motor drive circuit capable of correcting an offset voltage of a drive current detection system including a temperature characteristic without adding a new circuit in view of the state of the related art described above, thereby suppressing an increase in cost. In this state, the detection accuracy of the drive current is ensured in such a state that the motor torque fluctuation can be suppressed.
An object of the present invention is to provide a technique capable of solving such a problem.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention basically employs, as a motor drive circuit technology, a control means such as a microcomputer originally provided for controlling a drive current of a motor, thereby controlling a temperature related in the motor drive circuit. The temperature characteristic of the offset voltage is calculated based on the information and the offset voltage information of the current detecting means for detecting the drive current from the inverter circuit, and the offset voltage is corrected based on the calculation result. Specifically, the present invention proposes a motor drive circuit having the above-described basic configuration, a motor drive method having the above-described basic operation over time, and a motor drive program.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 4 are explanatory views of an embodiment of the present invention. FIG. 1 is a diagram showing a configuration example of a motor drive circuit according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a temperature characteristic learning operation of an offset voltage of the motor drive circuit of FIG. FIG. 4 is a diagram showing an example of a temperature characteristic of an offset voltage of a drive circuit. FIG. 4 is an explanatory diagram of an offset voltage correcting operation based on the temperature characteristic learning operation of FIG.
In FIG. 1, 1 is a motor drive circuit, 2 is a motor as a load, 3 is an inverter circuit that converts DC to AC to form and output a drive current for the motor, and 4 is provided with a sensor such as a Hall element. Current detecting means for detecting a driving current from the inverter circuit 3; 5, a temperature detecting means for detecting a temperature of the inverter circuit 3 or a temperature or a temperature change in the motor driving circuit 1; The control circuit is a control circuit that includes a gate IC and the like and controls the entire motor drive circuit. The control circuit 6 detects and stores the offset voltage of the current detecting means 4 and based on the detected offset voltage information and the temperature information or the temperature change information detected by the temperature detecting means 5, The temperature characteristic is calculated and stored, the offset voltage is corrected including the temperature characteristic based on the stored calculation result, and a control signal for controlling the inverter circuit 3 in the corrected state is formed. A series of operations such as calculation and storage of the temperature characteristics of the offset voltage, correction of the offset voltage based on the stored calculation result, and formation of a control signal for controlling the inverter circuit 3 in the corrected state are as follows. , Based on a program set and stored in the control circuit 6. The program automatically causes the microcomputer to execute these operation procedures.
[0007]
FIG. 2 is an explanatory diagram of the operation of learning the temperature characteristics of the offset voltage of the current detecting means in the motor drive circuit of FIG. This operation is a learning operation in which the motor drive circuit is preliminarily operated and the temperature characteristics of the offset voltage of the current detecting means are calculated and stored in advance in order to accurately correct the offset voltage including the temperature characteristics. is there. In the following description, the components used in the motor drive circuit will be denoted by the same reference numerals used in FIG.
[0008]
In FIG.
(1) First, the operation of the motor drive circuit 1 is started (step S201).
(2) The drive current supplied from the inverter circuit 3 to the motor 2 is set to zero, and the offset voltage of the current detection means 4 at this time is taken in (step S202).
(3) The acquired offset voltage is stored in the memory in the control circuit 6 (step S203).
(4) The control circuit 6 determines whether to start driving the motor 2 (step S204).
(5) As a result of the determination, if the drive can be started, the control circuit 6 issues a command to output a drive current to the inverter circuit 3 to drive the motor 2 (step S205).
(6) The drive current (motor current) is detected by the current detection means 4 (step S206).
(7) Based on the offset voltage value stored in step S203, the offset when the drive current is detected by the current detection means 4 is corrected (step S207).
(8) As a result of the determination in step S204, when the drive cannot be started, that is, when the operation is terminated, the supply of the drive current to the motor 2 is cut off and the inverter circuit 3 or the motor drive circuit 1 The information based on the temperature or the temperature change in the inside and the offset voltage information of the current detecting means 4 are fetched (step S208).
(9) The temperature characteristics of the offset voltage of the current detecting means 4 are calculated based on the acquired temperature-related information and the offset voltage information, and the calculation result is stored in the memory (step S209) to learn the temperature characteristics of the offset voltage. The operation ends (step S210).
[0009]
FIG. 3 is a diagram illustrating an example of a temperature characteristic of the offset voltage of the current detection unit 4. This characteristic example is an example in which the offset voltage increases as the temperature increases.
3, for example, the offset voltage △ _{e 0} at the temperature _{t 0} and the reference offset voltage, when a temperature _{t 1,} the offset voltage △ _{e 1} is △ _{e 0} + △ _{e t1,} when the temperature _{t 2,} the offset voltage △ _{e 2} is the △ _{e 0} + △ _{e t2.} △ _{e t1,} △ _{e t2} respectively is variation in the offset voltage due to temperature. In step S202 and step S203 in FIG. 2, for example, when the temperature t ₀ is used as a reference, the above Δe ₀ is captured as an offset voltage and stored. In step S208 of FIG. 2, the temperature information _{t 0, t 1, t 2} , ... , or temperature change information _{t 1 -t 0, t 2 -t} 0, ... and the like, the offset voltage information △ _e 0, △ _{e 1,} △ _{e 2,} captures ... and, in step S209, based on these information, the temperature characteristic of the offset voltage, the variation △ _{e t1} the offset voltage due to temperature, △ _{e t2,} and calculates a ... Store in memory.
[0010]
FIG. 4 is an explanatory diagram of the offset voltage correction operation based on the temperature characteristic learning operation of FIG. Assuming that the operation 2 is performed in the first operation, the operation in FIG. 4 is performed, for example, in the second operation. Also in the description of FIG. 4, the components used in the motor drive circuit are denoted by the same reference numerals as those used in FIG.
In FIG.
(1) First, the operation of the motor drive circuit 1 is started (step S401).
(2) The drive current supplied from the inverter circuit 3 to the motor 2 is set to zero, and the offset voltage of the current detection means 4 at this time is taken in (step S402).
(3) The acquired offset voltage is stored in the memory in the control circuit 6 (step S403).
(4) The control circuit 6 determines whether to start driving the motor 2 (step S404).
(5) As a result of the determination, if the drive can be started, the control circuit 6 issues a command to output a drive current to the inverter circuit 3 to drive the motor 2 (step S405), and the drive current ( Motor current) is detected (step S406), and the temperature detecting means 5 detects the temperature or temperature change in the motor drive circuit 1 or the inverter circuit 3 (step S407) to determine whether or not the offset voltage needs to be corrected. (Step S408).
(6) If it is determined in step S408 that the offset voltage needs to be corrected, the offset voltage value stored in step S403 is offset by the temperature based on the calculation result in step S209 in FIG. variation of the voltage (△ _{e t1} in FIG. 3, △ _{e t2)} the correct (cancel) (step S409, the step S410).
(7) Correcting (cancelling) the offset voltage after the correction (the offset voltage (△ e _{0 in} FIG. 3) after removing the change due to temperature) as the offset voltage when the drive current is detected by the current detecting means 4. (Step S411).
(8) The drive current is detected by the current detection means 4 in the state where the offset voltage correction in step S411 is performed, a control signal is formed, the inverter circuit 3 is controlled, and the drive of the motor 2 is continued.
(9) On the other hand, if the result of determination in step S404 is that drive cannot be started, that is, if the operation is to be terminated, the operation is terminated.
(10) As a result of the determination in step S408, when it is not necessary to correct the offset voltage, the temperature monitoring is continued as it is.
[0011]
According to the above embodiment, in the motor drive circuit, the offset voltage of the drive current detection system including the temperature characteristic can be corrected using a microcomputer or the like originally provided as a control circuit without adding a new circuit. it can. As a result, the detection accuracy of the drive current can be ensured in a state where the increase in cost is suppressed, and the torque fluctuation of the motor can be suppressed.
[0012]
In the above embodiment, the information based on the temperature or the temperature change in the inverter circuit 3 or the motor drive circuit 1 and the offset voltage information of the current detecting means 4 are taken in step S208 in FIG. However, the present invention is not limited to this. For example, a configuration may be adopted in which the control circuit 6 captures such information while the current detection unit 4 is detecting the drive current.
[0013]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the detection accuracy of a drive current can be ensured in the state which suppressed the increase in cost as a motor drive circuit, and it becomes possible to suppress torque fluctuation of a motor.
[Brief description of the drawings]
FIG. 1 is a configuration example diagram of a motor drive circuit as one embodiment of the present invention.
FIG. 2 is an explanatory diagram of a temperature characteristic learning operation of an offset voltage of the motor drive circuit of FIG. 1;
FIG. 3 is a diagram illustrating an example of a temperature characteristic of an offset voltage of the motor drive circuit of FIG. 1;
FIG. 4 is an explanatory diagram of an offset voltage correcting operation based on the temperature characteristic learning operation of FIG. 2;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Motor drive circuit, 2 ... Motor, 3 ... Inverter circuit, 4 ... Current detection means, 5 ... Temperature detection means, 6 ... Control circuit.

Claims (6)

A motor drive circuit that detects a drive current from the inverter circuit and drives the motor by feedback control,
Temperature detection means for detecting a temperature or temperature change in the motor drive circuit,
Current detection means for detecting the drive current,
The temperature characteristic of the offset voltage is calculated based on the detected temperature information or the temperature change information and the offset voltage information of the current detection means, and the inverter circuit is controlled in a state where the offset voltage is corrected based on the calculation result. Control means for performing
A motor drive circuit characterized by comprising: A motor drive circuit that detects a drive current from the inverter circuit and drives the motor by feedback control,
Temperature detection means for detecting the temperature or temperature change of the inverter circuit,
Current detection means for detecting the drive current,
In the first operation, the temperature change of the offset voltage is calculated and stored based on the detected temperature information or the temperature change information and the offset voltage information of the current detecting means. Control means for correcting the offset voltage based on the stored temperature change information, and controlling the inverter circuit in the corrected state;
A motor drive circuit characterized by comprising: The control means, when the inverter circuit, the temperature detection means or the current detection means is in an abnormal state, erases the temperature information or the temperature change information and the offset voltage information at the time of the first operation, The motor drive circuit according to claim 2, wherein the motor drive circuit is configured to return to a state before the operation. 3. The motor drive circuit according to claim 1, wherein said control means is constituted by a microcomputer. A motor driving method for driving a motor with a controlled driving current from an inverter circuit,
Determining an offset voltage of the means for detecting the drive current, and detecting a temperature or a temperature change of the inverter circuit;
Calculating a temperature characteristic of the offset voltage based on the detected temperature information or temperature change information and the obtained offset voltage information;
Correcting the offset voltage based on the calculation result;
Controlling the inverter circuit with the offset voltage corrected;
And driving the motor with the drive current through the motor. A motor driving program for driving a motor with a controlled driving current from an inverter circuit,
On the computer,
A step of calculating and storing a temperature change of the offset voltage based on offset voltage information of the means for detecting the drive current and temperature information or temperature change information of the inverter circuit;
Correcting the offset voltage based on the stored temperature change information,
A procedure for controlling the inverter circuit with the offset voltage corrected,
And a motor driving program for driving the motor.

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