EP0202043A2
Expired / Lapsed
EP
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Control for a stepper motor or other synchronous motor
Assignee: ZF International UK Ltd
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Filing: 1986-04-23
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Granted: —
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Expires: 2006-04-23
Abstract
Abstract Closed loop control for a stepper motor or other synchronous motor. A digital/frequency interface (13) provides drive current to the motor (12) at a frequency determined by output of speed limiter (20). Required rate-of-change of speed is calculated and applied via rate-of-change limiter (29) to adder (30) which sums rate-of-change signal with existing speed signal. The required rate-of-change is calculated by a calculator in accordance with existing speed, remaining distance to run, and the predetermined rate-of-change signal, to ensure that motor is brought to rest in controlled fashion without overshoot which normally occurs in closed loop control with rate-of-change limitation.
Inventors
- 👤 Roderick Stewart Janes
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 06:28
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/416
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
253 words
A control for a stepper motor or other synchronous motor comprising a position transducer (14) providing a motor position signal representing the motor position, first means (11) for comparing said position signal with a set point signal representing a desired position and producing a position error signal representing the distance the motor has to travel before reaching the desired position; second means (30) providing a motor controlling output representing a desired speed of the motor; interface means (13) providing drive current to the motor at a frequency determined by said second means; third means (20) limiting the magnitude of said motor controlling output to a predetermined level such that the motor can run without slip; fourth means sensitive to said position error signal for supplying to said second means a rate-of-change signal representing a desired rate of change of speed; fifth means (29) limiting the magnitude of said rate-of-change signal to a predetermined level such that motor speed can follow the speed changes demanded, characterised in that said fourth means comprises a function generator which receives said position error signal, a signal related to the actual speed of running, and a signal representing the predetermined level to which the rate-of-change signal is limited by said fifth means as inputs and, at least during deceleration as the set point is approached, generates an output signal representing the required rate-of-change of speed necessary for the motor to be brought to rest at the set point, taking into account the limitation imposed by said fifth means.
Claim 2
Dependent Claim
253 words
A control for a stepper motor or other synchronous motor comprising a position transducer (14) providing a motor position signal representing the motor position, first means (11) for comparing said position signal with a set point signal representing a desired position and producing a position error signal representing the distance the motor has to travel before reaching the desired position; second means (30) providing a motor controlling output representing a desired speed of the motor; interface means (13) providing drive current to the motor at a frequency determined by said second means; third means (20) limiting the magnitude of said motor controlling output to a predetermined level such that the motor can run without slip; fourth means sensitive to said position error signal for supplying to said second means a rate-of-change signal representing a desired rate of change of speed; fifth means (29) limiting the magnitude of said rate-of-change signal to a predetermined level such that motor speed can follow the speed changes demanded, characterised in that said fourth means comprises a function generator which receives said position error signal, a signal related to the actual speed of running, and a signal representing the predetermined level to which the rate-of-change signal is limited by said fifth means as inputs and, at least during deceleration as the set point is approached, generates an output signal representing the required rate-of-change of speed necessary for the motor to be brought to rest at the set point, taking into account the limitation imposed by said fifth means.
Claim 3
Dependent Claim
82 words
A control as claimed in claim 1 in which said function generator is a cyclically operating digital function generator having a first stage which calculates a stopping distance S d where where u is the existing speed F is the rate-of-change limit and h is the periodicity of the operating cycle; a second stage which calculates a distance error Δ S, where where Sa is the actual remaining distance; and a third stage which calculates the speed change Δ u required, where
Claim 4
Dependent Claim
51 words
A control as claimed in claim 1 in which said function generator is a cyclically operating digital function generator producing an output Δ u as follows where F is rate of change limit Sa is the position error u is the speed; and h is the periodicity of the operating cycle.
Claim 5
Dependent Claim
50 words
A control as claimed in claim 2 or claim 3 further comprising means operable to detect when the absolute value of the speed [u] is less than the value of the rate-of-change limit F and to set to value of Δ u in these circumstances to Sa - u h
References Cited (Backward Citations)
No citation records indexed.
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