JPH06292389A - Driving device for motor - Google Patents

Abstract

PURPOSE:To provide a motor driving device in which the controllability of a motor is increased by adding correction to a current command value or a current detection value so that the relation between the current command value and a motor current value becomes linear. CONSTITUTION:Correction is added to a current command value C to obtain a correction command value C'. When a command value output C'', a current detection voltage value C''' and a motor current C'''' are sequentially sought from the correction command value C', finally, a motor current with respect to the command value C makes C''''. Thereby, even when a current detection part has a non-linear element, the relation between the command value C and a motor current C'''' can be made linear to be able to perform precise motor control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for driving and controlling a motor by controlling a current flowing through the motor,
In particular, the present invention relates to a technique for controlling a motor torque by comparing a current command value with an actual motor current and controlling the motor current.

[0002]

2. Description of the Related Art FIG. 1 shows an example of a motor drive device on which the present invention is based. The motor has four switching elements T
It is connected in a bridge composed of UL, TDL, TUR, and TDR, and controls the conduction of each switching element to control the current flowing through the motor and drive control of the motor. For example, when the motor is normally rotated, each switching element is driven as shown in FIG. Specifically, in the section A of FIG. 2, the switching elements TUL, TDR
When the switching element is turned on and the switching elements TDL and TUR are turned off, a current i _M flows through the motor M. The current i _R also flows through the current detection resistor (shunt resistor) R1. On the other hand, in the section B, the switching elements TDL, TUR
When the switching elements TUL and TDR are also turned off, the current flowing in the motor is regenerated to the power source V1 through the diode connected to the switching elements TDL and TUR. At this time, the current detection resistor R
1, a current flows in the direction opposite to the direction of i _R shown in FIG. In this way, by repeatedly turning on / off the switching elements TUL and TDR, the current i _M flowing through the motor M is increased.
To control.

In this type of motor drive device, a current detection circuit 1 as shown in FIG. 3 is often used in order to simplify the drive circuit. In the figure, the part 11 is
The voltage detected by the current flowing through the current detection resistor R1 is half-wave rectified. In addition, in the part 12 the half-wave rectified voltage in the part 11 is applied to the switching element TUL,
When the TDR is on, it is held in the capacitor 13, and when the switching elements TUL and TDR are off, the motor current iM is detected in a pseudo manner by discharging through the resistor 14. FIG. 4 shows operation waveforms at this time. In such a current detection circuit 1, when the switching elements TUL and TDR are on for a short time, the motor current i _M cannot be accurately detected, and the motor current-motor current detection value (current (Detection characteristics)
Has a non-linear characteristic with an offset, as shown by the solid line in FIG. (In the figure, the dashed-dotted line is the ideal linear characteristic.)

FIG. 6 shows the relationship between the command value and the actually flowing motor current when an analog current loop capable of flowing a current faithful to the command voltage is used in the drive control circuit 2 of FIG. In FIG. 6, it is divided into four parts by a broken line, and (1) is the relationship between the command value and the command value output,
(2) is the relation between the current detection voltage value and the motor current,
(3) shows the relationship between the motor current and the command value.
(4) is meaningless. In FIG. 6, (3) is finally obtained by following (1) → (2). In particular,
In (1), when the value A is given as the command value, the command value output voltage (D / A value in FIG. 1) becomes A ′.
When an analog current loop is used for the drive control circuit 2, since the command value output voltage and the current detection voltage value are ideally controlled to match, the command value output voltage A ′ and the current detection voltage A ″ are Controlled to match. as a result,
In (2), since the relationship between the motor current and the current detection voltage value has a non-linear characteristic, the current detection voltage A ″
The motor current corresponding to is A ″ ″. Finally,
In (3), when the command value is A, the motor current is A '.
It becomes "". Similarly, for the command value B, the current flowing through the motor is B ″ ″. Thus, when the relationship between the current detection voltage value and the motor current (current detection characteristic) has a non-linear element, as shown in (3), the motor current flowing with respect to the command value is not linear and the dead zone It becomes non-linear with.

[0005]

However, in the motor drive device having the current detection characteristic having the non-linear element as described above, since the relationship between the current command value and the motor current value is not linear, the electric power steering system is not provided. like,
In the case of a device that requires a current to flow according to the torque command, the dead zone increases and the feeling is deteriorated. Further, since the current detection voltage value is non-linear, there is a difference between the detection voltage and the actual value, which hinders the fail-self processing for dealing with a case where an overcurrent flows.

The present invention solves the above-mentioned problems, and by correcting the current command value or the current detection voltage value, the relationship between the current command value and the motor current value becomes linear, An object of the present invention is to provide a motor drive device that improves the controllability of the motor.

[0007]

In order to achieve the above-mentioned object, the invention of claim 1 provides a detection means for detecting a current flowing through a motor, and a current detection value and a current command value detected by the detection means. In a motor drive device comprising a motor control means for comparing and controlling the motor based on the comparison result, and generating a torque according to the current command value, a correction for correcting the current command value or the current detection value. It is equipped with means. According to a second aspect of the invention, in the motor drive device according to the first aspect, the correction means corrects the current command value so as to correct the non-linear element of the current detection means. According to a third aspect of the invention, in the motor drive device according to the first aspect, the correcting means corrects the detected current value so as to correct the non-linear element of the current detecting means. According to a fourth aspect of the invention, in the motor drive device according to the third aspect, the fail-safe process is performed based on the corrected current detection value.

[0008]

According to the structures of claims 1 to 3, the current command value or the current detection value is corrected by the correction means so that the relationship between the current command value and the current value flowing through the motor becomes linear. The motor is drive-controlled. Claim 4
According to this configuration, the current detection value is corrected by the correction means, and the fail-safe processing such as overcurrent is performed by the corrected current detection value.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows a motor drive device according to a first embodiment of the present invention.
The motor driving device includes four switching elements TUL, T
DL, TUR, TDR, a current detection resistor (shunt resistor) R1 and a current detection circuit 1 for detecting a current flowing through the motor M, a drive control circuit 2, a gate drive circuit 3 for controlling each switching element, and a CPU 4. , And a power source V1. The drive control circuit 2 uses an analog current loop. FIG. 2 shows operation waveforms of each part of the motor drive device. In the figure, i _M is the current value flowing through the motor M, i _R is the current value flowing through the shunt resistor R1, and the current detection voltage is the voltage value detected by the current detection circuit 1. FIG. 3 shows a specific example of the current detection circuit 1.

In this embodiment, the current command value, that is, C
By correcting the D / A output of PU4, the relationship between the current command value and the motor current is made linear. FIG. 7 (4) shows the procedure for correcting the current command value, and the correcting means is achieved by the CPU 4. For example, the command value C is corrected to obtain a correction command value C '. Then, when the correction command value C ′ is given, the command value output voltage becomes C ″. When an analog current loop is used in the drive circuit, control is performed so that the command value output voltage C ″ and the current detection voltage C ″ ″ match. The motor current at the current detection voltage C ″ ″ is C ″ ″ ″. Finally, when the command value is C, the motor current becomes C ″ ″ ″. Similarly, when the command value is D, the motor current becomes D ″ ″ ″. Therefore, although the relationship between the motor current and the current detection voltage value (current detection characteristic) is non-linear, the relationship between the command value and the motor current is linear as shown in FIG. 7C.

FIG. 8 is a flow chart when the above-mentioned processing for correcting the command value is performed by the software of the CPU 4. When the current command value is calculated by the torque or the vehicle speed (# 1), the current command value is corrected (# 2) as shown in FIG.
The A value is output (# 3).

FIG. 9 shows a second embodiment of the present invention. In this embodiment, the current detection voltage value is corrected to make the relationship between the current command value and the motor current linear. In FIG. 9, (1) is the relationship between the detected voltage and the motor current having a non-linear element, (2) is the relationship between the detected voltage and the corrected detected voltage according to the present embodiment, and (3) is the corrected detection with respect to the motor current. Indicates the voltage. The current detection voltage value becomes F ′ with respect to the motor current F, and this current detection voltage value F ″ (= F
′) Is corrected and corrected detection voltage value F ″
'Is obtained. Similarly, for the motor current E, the correction detection value E ″ ″ is obtained. Therefore, the motor current can be linearly detected as shown in FIG. 9C, even though the relationship (current detection characteristic) of the current detection voltage value with respect to the motor current is non-linear.

FIG. 10 shows a third embodiment of the present invention. Even when the current detection circuit having the non-linear element shown in FIG. 6 is used, the detection voltage value corrected by the correction means shown in FIG. 9 is used in FIG. 10 (2). As shown, the relationship between the command value and the motor current is linear.

FIG. 11 shows a modification of the motor drive device.
The operation waveform and current detection circuit 1 is the same as that described above, and instead of the drive control circuit 2, a PWM circuit 12 that modulates the pulse width to drive and control the motor M is provided. 12
Is the CPU 4 which performs the above-described processing for correcting the detected current value.
3 is a flow chart when it is implemented by the software of FIG. When the current command value is calculated by the torque or the vehicle speed (# 11), the current detection voltage is corrected as shown in FIG. 9 (2) (# 12). The current command value and the current detection voltage correction value are compared (# 13), and the D / A value is output from the CPU 4 based on the comparison result (# 14). FIG. 13 is a flowchart when the fail-safe processing is executed by the software of the CPU 4. After the current detection voltage is actually corrected to a desired value (# 21), fail-safe processing such as turning off a relay or a gate is performed based on the current detection voltage (# 22). Since the relationship between the corrected detected value and the motor current is linear, the detected voltage and the actual voltage value match, and the error is reduced. The process of correcting the detected current value may not be included in the above subroutine, and may be included in another subroutine, for example, a command value creation subroutine.

[0015]

As described above, according to the first to third aspects of the present invention, even if the current detecting section includes a non-linear element, the current command value or the current detection voltage value is corrected to control the drive of the motor. However, since the relationship between the motor current and the current command value is linear, the controllability can be improved. Therefore, for example, even in the case of the electric power steering device that supplies the motor current according to the torque command, the dead zone is not present and the motor control corresponding to the current command value can be performed. According to the invention of claim 4, the current detection value is corrected, and the fail-safe processing is performed with respect to the over-current or the like other than the control by the correction value. Therefore, the fail-safe processing can be surely performed.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a motor drive device.

FIG. 2 is an operation waveform chart of each part of the motor drive device.

FIG. 3 is a specific circuit diagram of a current detection circuit.

FIG. 4 is an operation waveform diagram of each part of the current detection circuit.

FIG. 5 is a diagram showing a conventional motor current-motor current detection value characteristic.

FIG. 6 is a diagram showing a conventional command value-motor current characteristic.

FIG. 7 is a diagram showing a command value-motor current characteristic according to the first embodiment of the present invention.

FIG. 8 is a flowchart showing a processing procedure for correcting a command value.

FIG. 9 is a diagram showing a motor current-correction detection value characteristic.

FIG. 10 is a diagram showing a command value-motor current characteristic according to the second embodiment.

FIG. 11 is a circuit diagram of a motor drive device according to a modification.

FIG. 12 is a flowchart showing a processing procedure for correcting a detected current value.

FIG. 13 is a flowchart showing a processing procedure for performing fail-safe processing.

[Explanation of symbols]

 1 current detection circuit 3 gate drive circuit 4 CPU TUL, TDL, TUR, TDR switching element M motor R1 current detection resistor (shunt resistor)

Claims (4)

[Claims] 1. A detection means for detecting a current flowing through a motor, and a motor control means for comparing a current detection value detected by the detection means with a current command value and drivingly controlling the motor based on the comparison result. In the motor drive device for generating a torque according to the current command value, the motor drive device is provided with a correction unit for correcting the current command value or the detected current value. 2. The motor drive device according to claim 1, wherein the correction means corrects the current command value so as to correct the non-linear element of the current detection means. 3. The motor drive device according to claim 1, wherein the correction means corrects the current detection value so as to correct the non-linear element of the current detection means. 4. The motor drive device according to claim 3, wherein fail-safe processing is performed based on the corrected current detection value.