JPH03173377A - Motor controller - Google Patents

Abstract

PURPOSE:To prevent the overshooting of the number of revolutions of a motor by a method wherein the driving of the motor is stopped temporarily for a predetermined period of time after a predetermined time has elapsed from the starting of the motor and, then, the driving of the motor is reopened. CONSTITUTION:When a motor ON signal becomes a low level, the input of an inverter 6 is reduced gradually in accordance with a resistor R5 and the time constant of a capacitor C3. When the waveform of the signal has passed the converting level of the inverter 6, the output of the inverter 6 is inverted and a pulse is obtained through a differentiating circuit consisting of a capacitor C4 and a resistor R6. As a result, the motor ON signal, outputted from an OR gate 7, is provided with a waveform, in which a pulse having the pulse width (determined by a capacitor C4 and the resistor R6) of a time T2 is added after the delay of a time T1 (determined by the resistor R5 and the capacitor C3) from the change of the low level of the actual motor ON signal. According to this method, the control system of the number of revolutions of a motor, which is prominent in transient response property and has no overshooting, may be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a motor control rB device, particularly a motor control device that controls the rotational speed of a motor at a constant speed according to the mechanical load of the motor to be driven and the motor drive torque. It is related to.

[Prior Art] Conventionally, it has been used as a motor for driving a magnetic disk in a magnetic disk device. ! A direct drive motor is known that has a structure in which a rotor having an IUI magnet and a stator having a drive coil face each other.

Normally, in applications such as magnetic disk drives, such direct drive motors need to be driven to rotate at a constant speed, so a configuration in which a servo circuit is provided in such a motor drive system is known.

Figures 2 and 3 show the configurations of conventional servo systems, respectively. Figures 2 and 3 both show the torque constant input to the motor in the form of voltage, current, etc. from the mechanical load and drive system. It is illustrated as a system in which the input conditions are reflected in the rotation speed. The only difference between FIGS. 2 and 3 is the configuration of the integrating circuit 1.

In FIGS. 2 and 3, reference numeral 2 is a transfer function determined by the inertia of the motor and its drive system, and its input is input from the motor's mechanical load and the drive amplifier 4 in the form of current, voltage, etc. The torque constant is 5.

Depending on the addition result of these two input conditions, the transfer function 2
The motor rotation speed is obtained as the output. This rotational speed is input to an integrating circuit 1 via a rotational speed sensor 3 consisting of an encoder or the like attached to a motor shaft or the like.

The output of the integrating circuit 1 acts on the input of the drive amplifier 4 which determines the torque constant 5, and the integrated integrating circuit 1 controls the rotational speed of the motor to a predetermined constant value.

Integrating circuit l is composed of an operational amplifier, etc., and resistors R1, R2, capacitor C1,
An integral constant by C2 is connected. In the case of FIG. 2, diodes DI and D2 as clamp circuits are further added to the negative feedback circuit of the integrating circuit l.

In addition, in the case of Fig. 3, the diode Di and the resistors R3 and R
A limiter circuit with a gain of 4 is added.

Problems to be solved by the invention C] The clamp circuit in FIG. 2 and the limiter circuit in FIG.
In either case, gain control of the integrating circuit 1 is temporarily activated at the time of starting the motor, thereby preventing rotational speed overshoot at the time of starting the motor.

FIG. 4 shows changes in the rotational speed when the motor is started in the configurations shown in FIGS. 2 and 3. The upper part of Figure 4 is the motor on signal.
Start the motor by low level. The broken line in the lower part of Figure 4 shows the change in rotation speed when no clamp or limiter circuit is added in the configurations shown in Figures 2 and 3, and the solid line shows the change in rotation speed in the configurations shown in Figures 2 and 3. It shows.

As shown in the figure, by adding a clamp or limiter circuit to the integrator circuit l that negatively feeds rotation speed information back to the drive system, the gain of the integrator circuit l is reduced in the transient state until the motor shifts to a constant speed drive state. This controls overshoot.

However, when the inertia of the motor rotor is small, the amount of overshoot per revolution becomes large. In order to increase the amount of overshoot regulation, it is necessary to reduce the voltage drop between the negative terminal of the operational amplifier and the output of the clamp or limiter circuit shown in FIGS. 2 and 3, and in this case, the starting torque decreases. Furthermore, if the starting torque is configured not to be reduced, there is a problem in that sufficient overshoot regulation does not work.

An object of the present invention is to provide a configuration that solves the above problems and effectively prevents overshoot of the motor rotation speed.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a motor that maintains the rotational speed of the motor at a constant speed according to the mechanical load of the motor to be driven and the motor drive torque. In the control device, a configuration is adopted in which a means is provided for temporarily stopping the motor drive for a predetermined period of time after a predetermined period of time has elapsed after starting the motor, and then restarting the drive.

[Function] According to the above configuration, when the motor is started, the motor drive is temporarily stopped for a predetermined period, and after the rotation speed of the motor reaches the target value due to inertia, the motor drive is restarted. Prevent number overshoot.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings. FIG. 1 [A] shows the structure of a motor drive system employing the present invention.

In FIG. 1A, the motor is illustrated as a processing system that handles rotation speed information, similar to FIGS. 2 and 3.

In the configuration of FIG. 1(A), the clamp circuit or limiter circuit of FIGS. 2 and 3 is deleted, and the integration constant of the integrating circuit 1 is set to only the resistor R2 and capacitors C1 and C2, and the integrating circuit l
The rotation speed during steady operation is determined by negative feedback by PAIti.
This is the basic configuration for convergence.

That is, in this embodiment, unlike the conventional example, a configuration is not adopted in which overshoot is restricted by gain control of the integrating circuit l, but instead.

The circuit shown in FIG. 1(B) is provided at the input section of the motor-on signal. This motor-on signal is used as a starting signal for the drive amplifier 4.

In FIG. 1(B), numeral 6 is an inverter, and numeral 7 is an O
An R gate is shown, and a negative logic active motor-on signal is input to one of the OR gates 7 (preferably constructed from a Schmitt trigger or the like).

Further, the motor-on signal is guided to the input of the inverter 6 via an integrating circuit consisting of a resistor R5 and a capacitor C3. Further, the output of the inverter 6 is led to the other input of the OR gate 7 via a differentiating circuit consisting of a capacitor C4 and a resistor R6.

FIG. 1(C) shows the waveform timing in the circuit of FIG. 1(B). When the motor-on signal becomes low level, the input of the inverter 6 changes as shown in FIG. 1(C) according to the time constant of resistor R5 and capacitor C3. It gradually decreases as shown in the second row.

When this waveform passes the inversion level of inverter 6, the output of inverter 6 is inverted as shown in the third stage of FIG. 1 (C), and this positive edge is connected to capacitor C4 and resistor R6.
A pulse as shown in the fourth stage of FIG. 1(C) is obtained through a differentiating circuit consisting of the following.

As a result, the motor-on signal output from the OR gate 7 is delayed by the time TI (due to resistor R5 and capacitor C3) from the actual change of the motor-on signal to low level, as shown in the upper part of FIG. 1(D). The waveform is obtained by adding pulses with a pulse width of T2 (based on capacitor C4 and resistor R6).

Therefore, in the above configuration, the motor drive is delayed for 12 hours immediately after the motor is turned on, and after T1 hours, the motor drive is cut off for 12 hours, and the motor is turned on again at the timing when the motor rotation speed reaches the target value due to inertia (after TI+T2 hours). By doing so, it is possible to provide a motor rotational speed control system with excellent transient response characteristics without overshoot (the curves shown by the broken line in FIG. 1(D)).

It goes without saying that the delay time TI and pulse width T2 determined by the integrating and differentiating circuit shown in FIG. 1(B) are determined depending on the inertia of the motor and motor drive system.

In the above example, the motor-on signal is processed by hardware means as shown in FIG. 1(B). Diagram (D)
It goes without saying that the same m effect can be obtained by forming a motor-on drive signal as shown in the upper row.

In this case, since a hardware circuit as shown in FIG. 1(B) is not required, the manufacturing cost of the device can be further reduced.

[Effects of the Invention] As is clear from the above, according to the present invention, in a motor control device that controls the rotation speed of the motor at a constant speed according to the mechanical load of the motor to be driven and the motor drive torque, , after a predetermined period of time has elapsed, the motor drive is temporarily stopped for a predetermined period of time, and then the drive is restarted.
By temporarily stopping the motor drive for a predetermined period and restarting the motor drive after the motor rotation speed reaches the target value due to inertia, overshoot of the rotation speed can be prevented, and the motor rotation speed can be maintained from the time of startup. It has the excellent effect of being able to control the number of rotations with high precision.In applications such as magnetic disk drives, the time required to stabilize the rotational speed is shortened and faster processing becomes possible.

[Brief explanation of the drawing]

FIG. 1(A) is a block diagram showing the configuration of a motor control system adopting the present invention, and FIG. 1(B) shows a control circuit for a motor-on signal used in the control system of FIG. 1(A). The circuit diagram, FIG. 1(C) is a timing chart diagram showing the operation of the circuit in FIG. 1(B), and FIG. 1(D) is a timing chart diagram showing the operation of the circuit in FIG. 1(A).
A timing chart diagram showing the control of the motor rotation speed obtained by the configuration of (C), FIGS. 2 and 3 respectively show conventional motor control having overshoot control means by gain control of a negative feedback system of rotation speed information. A block diagram showing different configurations of the circuit, Figure 4 is similar to Figure 2,
FIG. 4 is a timing chart diagram showing how the motor rotation speed is controlled in the horizontal and vertical directions of FIG. 3; l...Integrator circuit 2...Transfer function 3...Rotation speed sensor 4...Drive amplifier 5...Torque constant 6...Inverter 7...OR gate Cl-C4...Capacitor R1 , R2, R5, R6...Resistance top-IM'1ftll! r, nof O,,'7eth +Z(
A) Rental drawing 1 (B)

Claims (1)

[Scope of Claims] 1) In a motor control device that controls the rotation speed of the motor at a constant speed according to the mechanical load of the motor to be driven and the motor drive torque, after a predetermined period of time has elapsed after starting the motor, for a predetermined period of time, A motor control device comprising means for temporarily stopping motor drive and then restarting the drive.