Power converter for a switched reluctance motor
First Claim
1. A power conversion apparatus for a switched reluctance motor having n-windings, each winding having a first end and a second end comprising:
- means for rectifying line voltage supplied to the motor, said rectifying means having a first electrical side and a second electrical side, the first end of each of said n-windings of said motor being electrically connected to the first side of said rectifying means;
switch means electrically connected to said n-winding for selectively energizing the n-winding of said motor most capable of converting electrical energy to useful work;
capacitor means electrically connected between the second end of each of said n-windings and the second side of said rectifying means, said capacitor means storing any unconverted portion of the energy of said n-windings and returning it to said n-windings during subsequent cycles, said switch means including a capacitor discharge switch for discharging said capacitor means through said windings, said last mentioned switch being electrically connected between said second end of each of said n-windings and the first side of said rectifying means;
switch control means for controlling operation of said switch means and said discharge switch for producing an energy period for supplying electrical energy to the n-motor windings which is equal to at least 2(1/cos(Eb/Vpk) radians for each line voltage cycle, where Eb is the motor'"'"'s back emf, and Vpk is the peak voltage of the rectified line voltage; and
means for preventing flow of current from the capacitor means toward the rectifying means so that substantially all the current which flows from the capacitor means flows to said n-windings when the capacitor means is discharged through the discharge switch.
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Accused Products
Abstract
Power conversion apparatus (10) for an n-winding switched reluctance motor (M). A rectifier circuit (12) rectifies line voltage supplied to the motor. A switching circuit (14) supplies, at any one time, electrical energy to the motor winding most capable of converting it to mechanical work. A storage capacitor (C1) stores any unconverted portion of the energy and returns it to the winding during subsequent cycles. The switching circuit provides a substantially long conduction period 2 (θ) for supplying electrical energy to the motor during each line voltage cycle. This permits use of a substantially smaller energy storage capacitor and results in a higher input power factor for circuit operation. Circuits for precharging the storage capacitor are eliminated. The switching circuit is capable of more modes of operation than previous circuits, while using fewer components, and therefore provides a lower cost design.
53 Citations
14 Claims
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1. A power conversion apparatus for a switched reluctance motor having n-windings, each winding having a first end and a second end comprising:
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means for rectifying line voltage supplied to the motor, said rectifying means having a first electrical side and a second electrical side, the first end of each of said n-windings of said motor being electrically connected to the first side of said rectifying means; switch means electrically connected to said n-winding for selectively energizing the n-winding of said motor most capable of converting electrical energy to useful work; capacitor means electrically connected between the second end of each of said n-windings and the second side of said rectifying means, said capacitor means storing any unconverted portion of the energy of said n-windings and returning it to said n-windings during subsequent cycles, said switch means including a capacitor discharge switch for discharging said capacitor means through said windings, said last mentioned switch being electrically connected between said second end of each of said n-windings and the first side of said rectifying means; switch control means for controlling operation of said switch means and said discharge switch for producing an energy period for supplying electrical energy to the n-motor windings which is equal to at least 2(1/cos(Eb/Vpk) radians for each line voltage cycle, where Eb is the motor'"'"'s back emf, and Vpk is the peak voltage of the rectified line voltage; and means for preventing flow of current from the capacitor means toward the rectifying means so that substantially all the current which flows from the capacitor means flows to said n-windings when the capacitor means is discharged through the discharge switch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A power converter and motor comprising:
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a switched reluctance motor having n-windings associated with it, each of said n-windings having a first end and a second end; a rectifier for rectifying the voltage supplied to said power converter, said rectifier having a first electrical side and a second electrical side, the first end of each of said n-windings being electrically connected to said first electrical side of said rectifier, a second end of said n-windings being electrically connected to a common connection point; a plurality of winding switches electrically connected one each between the second end of said n-windings and the second side of said rectifying means; a capacitor electrically connected between sad common connection point and the second side of said rectifying means a discharge switch electrically connected between said common connection point and the first side of said rectifying means; switch control means electrically connected to said plurality of winding switches and said discharge switch for controlling the duration and magnitude of electrical energy supplied to respective ones of said n-windings; and means for preventing flow of current from the capacitor toward the rectifier so that substantially all the current which flows from the capacitor flows to said n-windings when the capacitor is discharged through the discharge switch. - View Dependent Claims (12, 13, 14)
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Specification