JPS6120239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power control system for an electrical actuator, such as a multiphase stepper motor.

One object of the present invention is to provide a system in which the power applied to an actuator winding is adjusted according to the degree of actuating capacity of the actuator or according to the actual electrical and physical conditions in the range in which the actuator operates. The goal is to achieve the following.

A power control system for an electrical actuator according to the invention comprises a central processing unit for supplying an excitation signal to a control channel for determining the state of excitation of the actuator, a power regulation unit for varying the excitation signal in the control channel, and a central processing unit. The control unit includes a control unit that receives a power control signal from the central processing unit and controls the power regulation unit, and the control unit responds to the power control signal from the central processing unit so that the power regulation unit can control the power regulation unit with a lower relative actuator.
The actuator excitation power is decreased during periods of high relative activity of the actuator, and the actuator excitation power is increased during periods of high actuator relative activity, or a constant actuator output is maintained. Preferably, the system includes a monitor unit for monitoring the operating status of the actuator and providing signals representative of the status to a central processing unit, which signals are processed by the central processing unit to provide power control to the control unit. By providing a signal, the excitation signal is adjusted according to the situation. Taking a stepper motor as an example, during periods of relative slowness, that is, when the excitation pattern to the stepper motor windings does not change frequently, if the excitation pattern to the stepper motor windings changes frequently, It is usually unnecessary to maintain the average excitation current through the motor windings at the same level as would be required if the motor were to rotate at high speeds due to changes. By controlling the excitation in relation to the required performance of the stepper motor, the power consumption of the motor can be minimized. Alternatively, stepper motor characteristics may be selected to maximize performance in the envisaged application, thereby obviating the need to compromise that selection with factors such as reliability or high power dissipation.

An embodiment according to the invention will now be described by way of example with reference to the accompanying drawing, which is a block diagram of a stepper motor system with a power processing device.

In the illustrated example, an 8-bit central processing unit 2 and associated addressable memory 1 are arranged to exchange data and programs. The windings of the three-phase stepper motor 7 are energized in the manner described in our UK Patent Application No. 13257/78, and the signals outputted from the data latch 3 are also connected to the control unit 4. Further control can be provided by appropriate signals. Data is provided to a control unit 4 by a central processing unit 2 under the control of a program in memory 1. Additional data regarding the physical and electrical conditions of the stepper motor are also provided by the monitor unit 8 associated with the motor 7.
are obtained and processed by the central processing unit 2 to provide appropriate signals to the control unit 4. In this way, the use of the control unit 4 compensates for input voltage fluctuations so as to maintain a constant motor output torque independent of supply voltage fluctuations, and also
By compensating for variations in excitation winding temperature, a constant output torque can be maintained regardless of such variations. This compensation is accomplished by pulse width modulation performed by the power control unit 5, which is controlled by the control unit 4, on the signal from the data latch. Each time each excitation pattern of signals for the windings of the motor 7 is output from the central processing unit 2 to the data latch 3, additional data are output to the control unit 4 and, through the action of the power control unit 5, Determine the duration of said excitation pattern applied to the winding. As described in our UK Patent Application No. 13257/78, since the excitation pattern signals are output from the central processing unit 2 at equal intervals, if the interval at which the central processing unit outputs the excitation pattern signals is unit 4
When the duration determined by is short, the signal is only added for a portion of each interval. By varying the duration of the signal by the control unit 4, the active power to the windings of the motor 7 is controlled from a low value when the duration is short compared to the excitation signal interval to a maximum value when the duration is equal to said interval. can do.

When applying this technique to minimize excitation during periods of little or no movement of the stepper motor, a certain minimum output power is applied to prevent output position current due to load torque on the stepper motor. It is desirable to retain it. As long as the blocking current avoids unnecessary stimulation of the control loop and ensures that the exact value of the output shaft position is retained in the central processing system and memory even in the case of a failure of the position transducer, Power is particularly useful when the output position forms part of a closed loop control. Through the use of the techniques described above, stepper motors can be selected for optimal performance while minimizing self-heating and the resulting losses in efficiency and reliability. When used with closed-loop control using output position transducers, absolute knowledge of the output position is maintained within the central processing system and memory in combination with the technique of our UK Patent Application No. 13257/78. Transducer operational losses do not invalidate the loop integrity.

[Brief explanation of the drawing]

The accompanying drawings are block diagrams of stepper motor systems according to the present invention. 1...Memory, 2...Central processing unit, 3
...Data latch, 4...Control unit, 5...
...Power control unit, 6...Amplifier, 7...Stepper motor, 8...Monitor unit.

Claims (1)

Claims: 1. A central processing unit 2 for supplying excitation signal pulses to a control channel via a data latch and an amplifier 3 in the form of a succession of excitation patterns of a stepper motor winding; a power regulating unit 5 in said control channel for modulating the duration of said stepper motor windings before applying said stepper motor windings; and a control for receiving power control signals from said central processing unit 2 and controlling said power regulating unit 5 unit 4 and a monitor unit 8 for monitoring the physical and electrical environment of said stepper motor and generating data signals indicative of said environment.
and the excitation signal pulse duration of the stepper motor according to the physical and electrical environment of the stepper motor to minimize motor power requirements and maintain constant motor output torque in changing environmental conditions. characterized in that it includes a feedback channel for transmitting said data signal from the computer unit 8 to the central processing unit 2 for processing by the central processing unit 2 in order to provide a power control signal to the control unit 4 so as to be time modulated. Power control system for multi-phase stepper motor 7. 2. Furthermore, the motor unit monitors the operating state of the actuator and supplies a signal representing the state to the central processing unit, and this signal is processed by the central processing unit to supply a power control signal to the control unit, so that the above-mentioned state can be controlled. 2. The system of claim 1, wherein the excitation signal is adjusted. 3. The system of claim 1 or 2, wherein the power conditioning unit duration modulates the excitation signal in response to a signal from the control unit. 4. The actuator is a polyphase stepper motor, and the excitation signal is in a sequential pattern that is applied through a data latch and an amplifier to determine the excitation pattern of the stepper motor windings, and the excitation signal duration is 4. The system of claim 3, wherein the time modulation determines the duration of each pattern of signals. 5. The system of claim 3 and claim 4, wherein the central processing unit excitation signal is set by duration modulation of the central processing unit excitation signal to minimize the power requirements of the system. 6. The system of claim 4, wherein the central processing unit is configured to maintain a constant motor output torque.