Regenerative unipolar converter for switched reluctance motors using one main switching device per phase
First Claim
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1. A converter for a phase winding of a variable reluctance drive, said winding having a first side for connecting to the positive terminal of a dc source, said converter comprising:
- a phase switch for coupling a second side of said phase winding to the negative terminal of said dc source when said phase switch is conducting;
a phase unidirectional conducting device having its anode coupled to said second side of said phase winding so as to carry freewheeling current from said phase winding after said phase switch turns off;
a capacitor having one side coupled to the cathode of said phase unidirectional conducting device, said capacitor adapted to be charged by said freewheeling current to a voltage in excess of the dc source voltage; and
bleed means coupling said one side of said capacitor to said positive terminal of said dc source for bleeding at least a portion of the charge on said capacitor back to said positive terminal when the voltage across said capacitor rises to a predetermined value.
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Abstract
In a converter for a switched reluctance motor, a dump capacitor receives freewheeling current from each phase and resupplies the charge to the dc supply. In this manner, residual magnetic energy is recovered and phase current quickly reduced while the converter requires only one main switching device and one freewheeling device per phase and the converter allows a unipolar source to be used.
84 Citations
10 Claims
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1. A converter for a phase winding of a variable reluctance drive, said winding having a first side for connecting to the positive terminal of a dc source, said converter comprising:
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a phase switch for coupling a second side of said phase winding to the negative terminal of said dc source when said phase switch is conducting; a phase unidirectional conducting device having its anode coupled to said second side of said phase winding so as to carry freewheeling current from said phase winding after said phase switch turns off; a capacitor having one side coupled to the cathode of said phase unidirectional conducting device, said capacitor adapted to be charged by said freewheeling current to a voltage in excess of the dc source voltage; and bleed means coupling said one side of said capacitor to said positive terminal of said dc source for bleeding at least a portion of the charge on said capacitor back to said positive terminal when the voltage across said capacitor rises to a predetermined value. - View Dependent Claims (2, 3)
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4. A converter for a multiphase variable reluctance drive, said drive including a plurality of phase windings, each phase winding having a first side for connecting to the positive terminal of a dc source, said converter comprising:
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a plurality of phase switches, each phase switch, respectively, coupling a second side of a respective phase winding to the negative terminal of said dc source when each respective phase switch is conducting; a plurality of phase unidirectional conducting devices, each unidirectional conducting device, respectively, having its anode coupled to the second side of a respective phase winding so as to carry freewheeling current from its respective phase winding after the respective phase switch turns off; a capacitor having one side coupled to the cathode of each of said plurality of unidirectional conducting devices, said capacitor adapted to be charged by said freewheeling currents; and bleed means coupling said one side of said capacitor to said positive terminal of said dc source for bleeding at least a portion of the charge on said capacitor back to said positive terminal when the voltage across said capacitor rises to a predetermined value. - View Dependent Claims (5, 6, 7, 8)
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9. A method for recovering energy released from a phase winding of a switched reluctance drive during freewheeling of said phase winding after the commutation point, said phase winding being connected to a dc source, said method comprising the steps of:
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(1) transferring the charge released from said phase winding during freewheeling to a charge storage device; and (2) selectively bleeding at least a portion of the charge in said storage device back to said dc source, said bleeding step being terminated before the voltage across said storage device falls below the voltage across said dc source.
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10. A method for recovering energy released from a phase winding of a switched reluctance drive during freewheeling of said phase winding after the commutation point, said phase winding being connected to a dc source, said method comprising the steps of:
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(1) transferring the charge released from said phase winding during freewheeling to a charge storage device; and (2) selectively bleeding at least a portion of the charge in said storage device back to said dc source, said bleeding step being initiated when the voltage across said storage device is greater than the voltage across said dc source.
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Specification