Control method for a start-up control unit and an apparatus to make use of this method
AssigneeSchneider Electric SA
InventorsJean-Louis Chouffier, Hubert Cornilleau, Pascal Duclos
Life of this patent
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Abstract
A method for the control of a load, such as a motor, by means of a start-up controller (1) connected, on the one hand, to a fixed frequency alternating supply, and, on the other hand, to the motor, and including static switches associated with at least one phase of the motor and operated by a control circuit (2), characterized in that the electromagnetic torque (C.sub.m) of the motor is automatically controlled to a variable reference value (C.sub.cons) in the start-up or deceleration stage of the motor.
Claims8
A start-up controller for controlling a load having an electromagnetic stator, said controller comprising:
- a) a fixed frequency alternating electrical supply having an output connected to said load through a plurality of static switches;
- b) control means for outputting at least one trigger signal to said static switches;
- c) feedback control means for controlling an electromagnetic torque, said feedback control means further comprising:
- i) means for determining the electromagnetic torque, said determining means further comprising:
- a device for calculating the electromagnetic torque having an output;
- phase calculating means having an output;
- said phase calculating means including means for calculating a time between a predetermined input voltage phase of said electrical supply and said trigger signal;
- a device for calculating power transmitted to said load by said electrical supply outputting a power value using the output of the phase calculating means;
- a device for calculating stator losses outputting a power value;
- said device for calculating electromagnetic torque receiving power values outputted by said device for calculating transmitted power and said device for calculating stator losses;
- ii) comparator means for determining an error signal between said electromagnetic torque output and a reference value;
- iii) integrator means for integrating said error signal and outputting a triggering delay value to control the output of said control means.
A method for controlling a load having a stator by means of a start-up controller, said load connected to a fixed frequency alternating electrical supply through a plurality of static switches comprising the steps of:
- determining an electromagnetic torque of said load, said step of determining electromagnetic torque further comprising the steps of:
- calculating stator losses associated with said load;
- calculating a phase difference;
- said step of calculating a phase difference further comprising the step of calculating a time between a predetermined input voltage phase of said electrical supply and a trigger signal for triggering said static switches;
- calculating a transmitted power to said load from said phase difference, a fundamental current in at least one phase of said load, and a voltage of said electrical supply;
- calculating the electromagnetic torque of said load from said transmitted power and from said stator losses;
- determining an error signal from a comparison between said calculated torque and a reference value;
- and
- generating a triggering delay value from said error signal and using said triggering delay value to control said trigger signal.
Dependencies are inferred from the claim text.