Multilevel DC link inverter
First Claim
1. A circuit for controlling a three-phase machine having a stator with stator windings and a rotor, the circuit comprising:
- a plurality of commutation switches which are connected to supply current to the stator windings;
a plurality of dc source connections for receiving a plurality of incremental dc voltages and for applying a selected sum of said incremental dc voltages to said plurality of commutation switches to provide a base dc voltage, while controlling one of the incremental dc voltages to provide a varying pulsed signal to said commutation switches relative to said base dc voltage;
at least one sensor for sensing a parameter of the motor from which a speed and rotor position of the motor can be determined; and
a controller responsive to said sensor for determining the speed and rotor position of the motor, said controller being connected for control of said dc source connections to change base dc voltage in response to changes in speed of the motor without increasing current ripple in the stator windings substantially above a current ripple resulting from applying the varying pulsed signal derived from one of the incremental dc voltages to said commutation switches, said controller being connected also for control of said commutation switches to sequentially excite the stator windings of said motor.
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Accused Products
Abstract
A multilevel DC link inverter and method for improving torque response and current regulation in permanent magnet motors and switched reluctance motors having a low inductance includes a plurality of voltage controlled cells connected in series for applying a resulting dc voltage comprised of one or more incremental dc voltages. The cells are provided with switches for increasing the resulting applied dc voltage as speed and back EMF increase, while limiting the voltage that is applied to the commutation switches to perform PWM or dc voltage stepping functions, so as to limit current ripple in the stator windings below an acceptable level, typically 5%. Several embodiments are disclosed including inverters using IGBT'"'"'s, inverters using thyristors. All of the inverters are operable in both motoring and regenerating modes.
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Citations
19 Claims
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1. A circuit for controlling a three-phase machine having a stator with stator windings and a rotor, the circuit comprising:
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a plurality of commutation switches which are connected to supply current to the stator windings;
a plurality of dc source connections for receiving a plurality of incremental dc voltages and for applying a selected sum of said incremental dc voltages to said plurality of commutation switches to provide a base dc voltage, while controlling one of the incremental dc voltages to provide a varying pulsed signal to said commutation switches relative to said base dc voltage;
at least one sensor for sensing a parameter of the motor from which a speed and rotor position of the motor can be determined; and
a controller responsive to said sensor for determining the speed and rotor position of the motor, said controller being connected for control of said dc source connections to change base dc voltage in response to changes in speed of the motor without increasing current ripple in the stator windings substantially above a current ripple resulting from applying the varying pulsed signal derived from one of the incremental dc voltages to said commutation switches, said controller being connected also for control of said commutation switches to sequentially excite the stator windings of said motor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of controlling a three-phase machine having a stator with stator windings and a rotor, the circuit comprising:
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turning on in sequence a plurality of primary commutation switches connected to supply current to the stator windings;
receiving a plurality of incremental dc voltages and selecting a sum of the incremental dc voltages to apply to said plurality of commutation switches as a base dc voltage;
varying one of the incremental dc voltages to apply a varying pulsed signal to the commutation switches in relation to said base dc voltage;
sensing a parameter of the motor from which a speed of the motor can be determined;
determining a speed of the motor, and wherein the base dc voltage is selected in response to changes in speed of the motor without increasing current ripple in the stator windings substantially above a current ripple resulting from varying said one of the incremental dc voltages to apply the varying pulsed signal to said commutation switches; and
determining a rotor position of the motor, and turning on and off said commutation switches to sequentially excite the stator windings of said motor. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A circuit for controlling a three-phase machine having a stator with stator windings and a rotor, the circuit comprising:
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a plurality of commutation switches which are connected to supply current to the stator windings;
a plurality of voltage-controlled cells in cascade arrangement for applying a resulting dc voltage to said plurality of commutation switches, said resulting dc voltage comprising at least one of a plurality of incremental dc voltages corresponding to said plurality of voltage-controlled cells, at least one of said cells also providing a varying pulsed signal to said commutation switches;
at least one sensor for sensing a parameter of the motor from which a speed and rotor position of the motor can be determined; and
a controller responsive to said sensor for determining the speed and rotor position of the motor, said controller being connected for control of said dc source connections to change said resulting dc voltage in response to changes in speed of the motor without increasing current ripple in the stator windings substantially above a current ripple resulting from the varying pulsed signal supplied from said one of the voltage-controlled cells to said commutation switches. - View Dependent Claims (19)
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Specification