JP2739166B2 - Control method of motor drive device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control method for a motor drive device, and more particularly to a four-wheel steering device or an all-electric power steering device for a vehicle.

[Conventional technology]

FIG. 2 shows a general H-bridge circuit for driving a motor. In FIG. 2, 1 and 3 are upstream transistors, 2 and 4 are downstream transistors, 5 is a motor, TM1 to TM4 are gate terminals of transistors 1 to 4, and T is a power terminal to which power of voltage V _CC is supplied. It is.

Next, the operation in the case where the upstream transistor 1 is subjected to PWM control will be described with reference to FIG. In FIG.
(A) to (d) show ON / OFF of the transistors 1 to 4, and (e) shows the motor current. Transistor 1 PWM
During control by a signal, as shown in FIG. 3 (d), the transistor 4 is always on and the transistors 2 and 3 are always off. As shown in FIG. 3 (e), when the transistor 1 is on, a current that increases by a certain time constant flows through the motor 5, and when the transistor 1 is off,
The regenerative current I _S1 flows for the time indicated by the period T1 of the waveform 6.
This regenerative current _ISI is shown by a solid line A in FIG. Further, the hunting characteristic of the steering shaft stroke is shown by a dotted curve S1 in FIG.

[Problems to be solved by the invention]

As described above, in the conventional control method, only the regenerative current I _S1 flows for a certain period during which the transistor 1 is off, and the power generation control current does not flow, so that the necessary braking cannot be applied to the motor. Was. For this reason, hunting due to the inertia of the motor cannot be prevented.

The present invention has been made in view of such a point,
An object of the present invention is to provide a method for controlling a motor drive device that can prevent hunting due to inertia of a motor.

[Means for solving the problem]

In order to achieve such an object, the present invention provides a motor (5) by turning on a first upstream transistor (1) and a second downstream transistor (4) as a pair.
A current path from one direction to the other direction is formed, and the amount of current flowing through this current path is controlled by the first upstream transistor (1).
The second upstream transistor (3) and the first downstream transistor (2) are adjusted by PWM driving.
Are turned on in pairs to form a current path from the other direction to the motor (5) in one direction, and the amount of current flowing through this current path is PWM-driven to the second upstream transistor (3). In the control method of the motor driving device, the first upstream transistor (1) is turned on and then turned on during the on / off control of the first upstream transistor (1) by PWM driving. The first downstream transistor (2) is turned on during the non-conduction period until the current is turned off, and the motor (5) is short-circuited by using the first downstream transistor (2) as a conduction path. 5) A braking force is applied to the second upstream-side transistor (3) during the on / off control of the second upstream-side transistor (3) by the PWM drive from when the second upstream-side transistor (3) is turned off until it is turned on next time. Within the non-conduction period between Then, the second downstream transistor (4) is turned on, the motor (5) is short-circuited by using the second downstream transistor (4) as a conduction path, and a braking force is applied to the motor (5). Things.

[Action]

According to the present invention, the first upstream transistor (1)
During the on / off control by the PWM drive, the first downstream transistor (2) is in a non-conduction period between the time when the first upstream transistor (1) is turned off and the time when the first upstream transistor (1) is turned on next time. Are made conductive. Thereby, the first
The motor (5) is repeatedly short-circuited by using the downstream transistor (2) as a conduction path, and the power generation braking current flows repeatedly, and the instantaneous braking of the motor (5) is repeated. Also, during the on / off control of the second upstream transistor (3) by PWM driving, a non-conducting period from the time when the second upstream transistor (3) is turned off to the time when the second upstream transistor (3) is turned on next time Within the second downstream transistor (4)
Are made conductive. As a result, the motor (5) is repeatedly short-circuited by using the second downstream transistor (4) as a conduction path, and the braking current is repeatedly flown, whereby the instantaneous braking of the motor (5) is repeated.

〔Example〕

According to the control method of the motor drive device of the present invention, even during the PWM control, when the PWM signal is off, a predetermined transistor constituting the H-bridge circuit is turned on to short-circuit the motor.

FIG. 1 is a time chart for explaining one embodiment of a control method of a motor drive device according to the present invention. 1, (a) to (d) show ON / OFF of the transistors 1 to 4, and (e) shows a motor current. The difference from the conventional example is that the transistor 2 is turned on while the transistor 1 is turned off (see the hatched portion in FIG. 1B). The transistor 4 is always on as in the conventional example.

By controlling the transistor 2 in this manner, the motor current shown in FIG. 1 (e) flows. That is, during the period T2 when the transistor 1 is off, the regenerative current _IS2 shown by the waveform 7 flows to the motor 5, and during the period T3, the braking current _IS3 shown by the waveform 8 flows. The regenerative current I _S2 is indicated by a dotted line B in FIG. 2, and the power generation braking current I _S3 is indicated by a thick line C in FIG. As described above, the generation braking current I _S3 flows through the motor 5, so that braking can be applied to the motor 5, and hunting due to inertia of the motor can be prevented. The hunting characteristic at this time is shown by a solid line curve S2 in FIG.

In FIG. 2, the signals applied to the gate terminals TM1 to TM4 may be generated from a logic circuit or a microcomputer. Furthermore, in the implementation, the PWM control of the lower transistor (transistor 2 or transistor 4) when applying motor control to prevent transistor destruction, and the upper PWM control in FIG. As described above, according to the control method of the motor drive device according to the present invention, the first upstream transistor is turned on and off by PWM driving as described above. During the control, the first downstream transistor is turned on during a non-conduction period between the time when the first upstream transistor is turned off and the time when the second upstream transistor is turned on, and the second upstream transistor is turned off. During the on / off control by the PWM drive of the transistor, during the non-conduction period between the time when the second upstream transistor is turned off and the time when the second upstream transistor is turned on next, The second downstream transistor is rendered conductive, whereby the motor is repeatedly short-circuited, and the power generation braking current repeatedly flows, whereby the instantaneous braking of the motor is repeated. This has the effect of preventing hunting due to the inertia of the motor, and has the effect of greatly contributing to fail-safe. Furthermore, the power consumption of the diode connected in parallel with the transistor can be reduced.

[Brief description of the drawings]

FIG. 1 is a time chart for explaining an embodiment of a control method of a motor drive device according to the present invention, FIG. 2 is a circuit diagram showing a general H-bridge circuit, and FIG. FIG. 4 is a characteristic diagram showing a hunting characteristic of a steering shaft stroke. 1-4: Transistor, 5: Motor, TM1-TM4 ...
Gate terminal, T ... Power supply terminal.

Claims (1)

(57) [Claims] A first upstream transistor and a first downstream transistor whose main current paths are connected in series;
Similarly, a second upstream transistor and a second downstream transistor whose main current paths are connected in series, a series connection point of the first upstream transistor and the first downstream transistor, and And a motor connected between a series connection point of the upstream transistor and the second downstream transistor, wherein the first upstream transistor and the second downstream transistor are turned on as a pair. To form a current path from one direction to the other direction to the motor, and set the amount of current flowing through this current path to the first upstream transistor by PW.
While adjusting by the M drive, the second upstream transistor and the first downstream transistor are turned on as a pair to form a current path from the other direction to the motor in one direction, The amount of current flowing through this current path is set to PW by the second upstream transistor.
A method of controlling a motor drive device that is adjusted by performing M drive, wherein the first upstream transistor is turned on and off by PWM drive.
During the off control, the first downstream transistor is turned on during a non-conduction period between the time when the first upstream transistor is turned off and the time when the first downstream transistor is turned on, and the first downstream transistor is turned on. The motor is short-circuited by using a transistor as a conduction path to apply a braking force to the motor, and the second upstream transistor is turned on and off by PWM driving.
During the off control, the second downstream transistor is turned on during a non-conduction period between the time when the second upstream transistor is turned off and the time when the second downstream transistor is turned on, and the second downstream transistor is turned on. A method for controlling a motor driving device, characterized in that the motor is short-circuited by using a transistor as a conduction path to apply a braking force to the motor.