Speed Control of Variable-Speed Multiple-Phase Motors
AssigneeEmerson Electric Co.
InventorsPing Shan, Cai Bing Zhang
Life of this patent
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Abstract
Exemplary embodiments or implementations are disclosed of methods, apparatus, and systems for operating motors in variable speed situations. In an exemplary implementation, a method of controlling a variable-speed motor includes defining a control duration as a predetermined number of cycles of a multiple-phase power supply. Each speed in a range of speeds is defined by a corresponding number of the cycles of the control duration. Power is provided to the motor from the power supply at a selected one of the speeds, by enabling input from the power supply for the number of the cycles of the control duration corresponding to the selected speed.
Claims16
A method of controlling a variable-speed motor, the method comprising:
- defining a control duration based on a predetermined number of cycles of an alternating current (AC) frequency;
- defining each speed in a range of speeds by a corresponding fraction of the control duration;
- a controller providing a driver signal to an interface circuit for each of one or more phases of an AC power supply, to enable line voltage input to a variable-speed motor from the one or more phases for the fraction of the control duration corresponding to a selected one of the speeds;
- and
- each interface circuit detecting zero-crossing points of the line voltage independently of the controller and switching the line voltage input from the corresponding phase between “on” and “off” states at detected zero-crossing points of the line voltage input.
A method of controlling a variable-speed motor, the method comprising:
- a controller providing a driver signal to an interface circuit for a time corresponding to a fraction of a number of AC cycles by which a full-speed driver signal to the motor is defined, the fraction corresponding to a selected motor speed;
- and
- the driver signal enabling the interface circuit to switch a line voltage input to the motor on or off upon detection of zero-crossing of the line voltage input by a zero-crossing circuit of the interface circuit;
- the driver signal to the interface circuit being provided by the controller independent of the detection of zero-crossing of the line voltage input.
A system for controlling a variable-speed motor, the system comprising:
- a controller configured to provide a driver signal configured in accordance with an AC frequency;
- and
- an interface circuit configured to deliver one or more line voltage inputs to a load, each interface circuit having a corresponding zero-crossing circuit configured to detect zero crossing in the corresponding line voltage input;
- each interface circuit configured to:
- receive the driver signal from the controller;
- and
- based on the driver signal, enable or disable power through the corresponding line voltage input at the detection of zero crossing;
- the detection of zero crossing being performed independent of the drive signal.
Dependencies are inferred from the claim text.