Electric motor regulation to obtain desired speed curve
OwnerJean Evininventor
Life of this patent
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Abstract
Regulation of the speed of an electric motor is accomplished by counting the number of periods of AC current and modulating the pulses supplied to the motor. The speed of the motor is regulated according to a speed reference curve. The technique is especially suitable for operating a motor which controls a door.
Claims12
Method of regulating an alternating current electric motor having a rotor and connected to receive power from a power supply with an output which is variable depending on a predetermined speed reference (C) between two adjustable endmost angular positions (E.sub.I and E.sub.F) of the rotor spaced apart by an adjustable number of rotor revolutions and in which positions the speed is zero, this method comprising:
- (A) initialization by the steps of:
- determining a theoretical number (N) of complete periods (T) of AC current (i) required for feeding the motor to drive the rotor over angular movement between the endmost angular positions (E.sub.I and E.sub.F), storing the theoretical number in a memory, storing a table having an output providing variations in the power supply to theoretically achieve the predetermined speed reference (c) based on a chronological position (x) of said complete periods (T) in the theoretical number (N), and
- (B) operating the motor to provide the predetermined speed reference (c) by the steps of:
- counting an instantaneous number (N') of complete periods of AC current from a first one of said endmost angular positions to a second one of said endmost angular positions, and controlling the power from the power supply to the motor by accessing the stored table based on the instantaneous number (N').
A system for regulating an alternating current electric motor comprising:
- means (15) for determining and storing a total theoretical number (N) of complete periods (T) of AC current feeding the motor (1) required for going from a first endmost position (E.sub.I) to a second position (E.sub.F);
- means (16) which, depending on a first chronological position (X) of each of said periods (T) in a total number, establishes a table of variations of a power supply to be provided for the motor for theoretically complying with a predetermined speed reference (C);
- means (151) for counting a real number (N') of complete periods of current supplying the motor from the first endmost position to the second endmost position (E.sub.F);
- and
- means (161) which, depending on a second chronological positon (X') of the real number (N'), adapts the power supply to a value determined by the table.
Dependencies are inferred from the claim text.