Operation of an electrical machine
AssigneeSwitched Reluctance Drives Limited
InventorRosemary Anne Norman
Life of this patent
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Abstract
An electrical machine is controlled without using a physical rotor position detector. When the demanded torque output is low, a control method causes the machine to operate on fewer than all the phases, thus increasing the phase current and improving the resolution of the position detection algorithm. The method can include sampling the phase current of the machine, determining whether the phase current is above a predetermined threshold, reducing the number of active phases, and then deriving the value of rotor position from the increased phase current in the remaining phases.
Claims27
A method of operating a polyphase electrical machine, the method comprising:
- deriving a value of rotor position from a parameter of the machine;
- reducing the duty of at least one phase for a given output demand;
- and
- increasing the duty of the other phase(s) to compensate for the reduction in the duty of the at least one phase for the given output demand, thereby altering the value of the parameter used for rotor position detection.
A system for operating a polyphase electrical machine comprising:
- switch means for controlling energization for each of the phases;
- means for deriving a value of rotor position from a parameter of the machine;
- and
- control means, operably coupled to the switch means, for controlling the duty of each of the phases contributing to output of the machine, the control means being operable to reduce the duty of at least one phase for a given output demand, and to increase the duty of the other phase(s) to compensate for the reduction in the duty of the at least one phase for the given output demand and to alter the value of the parameter from which rotor position is derived.
A system for operating a polyphase electrical machine comprising:
- at least one switch adapted to control energization for each of the phases;
- and
- a controller operably coupled with the at least one switch, the controller being adapted to obtain a value of rotor position from a parameter of the machine, the controller further being adapted to control the duty of each of the phases contributing to output of the machine, to reduce the duty of at least one phase for a given output demand, and to increase the duty of the other phase(s) to compensate for the reduction in the duty of the at least one phase for the given output demand and to alter the parameter of the machine from which the value of rotor position is obtained.
Dependencies are inferred from the claim text.