Multi-level dc bus inverter for providing sinusoidal and PWM electrical machine voltages
First Claim
1. A circuit for controlling an ac machine having a stator with stator windings and a rotor, the circuit comprising:
- a full bridge network of commutation switches which are connected to supply at least one phase voltage to the stator windings;
a plurality of diodes, each in parallel connection to a respective one of the commutation switches for allowing conduction of current in a reverse direction to bypass each respective commutation switch;
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 full bridge network of commutation switches over successive time intervals to approximate a sinusoidal voltage; and
a controller connected for control of said dc source connections and said full bridge network of commutation switches to output a substantially sinusoidal phase voltage to the stator windings.
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Accused Products
Abstract
A circuit for controlling an ac machine comprises a full bridge network of commutation switches which are connected to supply current for a corresponding voltage phase to the stator windings, a plurality of diodes, each in parallel connection to a respective one of the commutation switches, a plurality of dc source connections providing a multi-level dc bus for the full bridge network of commutation switches to produce sinusoidal voltages or PWM signals, and a controller connected for control of said dc source connections and said full bridge network of commutation switches to output substantially sinusoidal voltages to the stator windings. With the invention, the number of semiconductor switches is reduced to m+3 for a multi-level dc bus having m levels. A method of machine control is also disclosed.
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Citations
20 Claims
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1. A circuit for controlling an ac machine having a stator with stator windings and a rotor, the circuit comprising:
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a full bridge network of commutation switches which are connected to supply at least one phase voltage to the stator windings;
a plurality of diodes, each in parallel connection to a respective one of the commutation switches for allowing conduction of current in a reverse direction to bypass each respective commutation switch;
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 full bridge network of commutation switches over successive time intervals to approximate a sinusoidal voltage; and
a controller connected for control of said dc source connections and said full bridge network of commutation switches to output a substantially sinusoidal phase voltage to the stator windings. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A polyphase control circuit for controlling an ac machine having a stator with stator windings and a rotor, the control circuit comprising:
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a plurality of full bridge networks of commutation switches which are connected to apply corresponding phase voltages to the stator windings;
a plurality of diodes, each in parallel connection to a respective one of commutation switches for allowing conduction of current in a reverse direction to bypass each respective commutation switch;
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 full bridge networks of commutation switches over successive time intervals to provide approximately sinusoidal phase voltages; and
the polyphase control circuit further comprising a controller connected for control of said dc source connections and said full bridge networks of commutation switches for each of the phase voltages to output substantially sinusoidal phase voltages to the stator windings. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method of controlling an ac machine having a stator with stator windings and a rotor, the method comprising:
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turning on in sequence a full bridge network of primary commutation switches connected to apply a phase voltage to the stator windings of the machine, said switches being turned on and off so as to produce a positive half cycle and a negative half cycle of said phase voltage;
producing a plurality of incremental dc voltages; and
applying a varying sum of the plurality of incremental dc voltages to said plurality of commutation switches to apply an approximately sinusoidal phase voltage having a positive half cycle and a negative half cycle. - View Dependent Claims (17, 18, 19, 20)
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Specification