Prime mover for operating an electric motor

Claim 1

A system comprising: an electric motor; a prime mover for generating dc electrical power; an inverter for converting the dc power to ac power, the ac power being supplied to the electric motor during motor operation; and a controller for controlling the inverter to ramp up current of the ac power and ramp up frequency of the ac power during startup of the electric motor, the frequency being ramped up after the current has been ramped up, the current and the frequency being ramped up to reduce motor inrush current.

Claim 2

A system comprising: an electric motor; a prime mover for generating dc electrical power; an inverter for converting the dc power to ac power, the ac power being supplied to the electric motor during motor operation; and a controller for controlling the inverter to ramp up current of the ac power and ramp up frequency of the ac power during startup of the electric motor, the frequency being ramped up after the current has been ramped up, the current and the frequency being ramped up to reduce motor inrush current.

Claim 7

A system comprising: an electric motor; a prime mover for generating ac electrical power; a dc link; a first rectifier, coupled between the dc link and an output of the prime mover, for converting the ac power from the prime mover to dc power and supplying the dc power to the dc link; a second rectifier adapted to convert backup ac power to dc power and directly place the converted backup power on the dc link in the event the prime mover fails; an inverter, coupled to the dc link, for converting the dc power on the dc link to ac power, the ac power being supplied to the electric motor during motor operation; and a controller for controlling the inverter to vary at least one of frequency and current of the ac power during operation of the electric motor.

Claim 8

A system comprising: an electric motor; a prime mover for generating ac electrical power; a dc link; a first rectifier, coupled between the dc link and an output of the prime mover, for converting the ac power from the prime mover to dc power and supplying the dc power to the dc link; a second rectifier adapted to convert backup ac power to dc power and directly place the converted backup power on the dc link in the event the prime mover fails; an inverter, coupled to the dc link, for converting the dc power on the dc link to ac power, the ac power being supplied to the electric motor during motor operation; and a controller for controlling the inverter to vary at least one of frequency and current of the ac power during operation of the electric motor.

Claim 9

A system comprising: an electric motor; a microturbine generator for generating dc electrical power, the microturbine generator including a turbine for converting gaseous heat energy into mechanical energy, an electrical generator for converting the mechanical energy produced by the turbine into electrical energy, and a rectifier having an input coupled to an output of the electrical generator, an output of the rectifier providing the dc power; an inverter for converting the dc power to ac power, the ac power being supplied to the electric motor during motor operation; and a controller for controlling the inverter to vary at least one of frequency and current of the ac power during operation of the electric motor, wherein the controller also controls the microturbine generator.

Claim 10

A system comprising: an electric motor; a microturbine generator for generating dc electrical power, the microturbine generator including a turbine for converting gaseous heat energy into mechanical energy, an electrical generator for converting the mechanical energy produced by the turbine into electrical energy, and a rectifier having an input coupled to an output of the electrical generator, an output of the rectifier providing the dc power; an inverter for converting the dc power to ac power, the ac power being supplied to the electric motor during motor operation; and a controller for controlling the inverter to vary at least one of frequency and current of the ac power during operation of the electric motor, wherein the controller also controls the microturbine generator.

Claim 11

A system comprising: an electric motor; a microturbine generator for generating dc electrical power, the microturbine generator including a turbine for converting gaseous heat energy into mechanical energy, an electrical generator for converting the mechanical energy produced by the turbine into electrical energy, a first rectifier having an input coupled to an output of the electrical generator, an output of the rectifier providing the dc power; an inverter for converting the dc power to ac power, the ac power being supplied to the electric motor during motor operation; and a controller for controlling the inverter to vary at least one of frequency and current of the ac power during operation of the electric motor; wherein the inverter includes a dc power bus, a dc-to-ac converter coupled between the dc power bus and the electric motor, and a second rectifier having an input adapted to receive utility power and an output coupled to the dc bus, an output of the first rectifier also being coupled to the dc power bus.

Claim 12

A system comprising: an electric motor; a microturbine generator for generating dc electrical power, the microturbine generator including a turbine for converting gaseous heat energy into mechanical energy, an electrical generator for converting the mechanical energy produced by the turbine into electrical energy, a first rectifier having an input coupled to an output of the electrical generator, an output of the rectifier providing the dc power; an inverter for converting the dc power to ac power, the ac power being supplied to the electric motor during motor operation; and a controller for controlling the inverter to vary at least one of frequency and current of the ac power during operation of the electric motor; wherein the inverter includes a dc power bus, a dc-to-ac converter coupled between the dc power bus and the electric motor, and a second rectifier having an input adapted to receive utility power and an output coupled to the dc bus, an output of the first rectifier also being coupled to the dc power bus.

Claim 19

A method of operating an electric motor, the method comprising the steps of: operating a prime mover proximate the motor to generate dc electrical power; using an inverter to convert the dc power to ac power; supplying the ac power directly to the motor; and controlling an inverter to vary current and frequency of the ac power during startup of the motor, the current being ramped up and then the frequency being ramped up during startup to reduce motor inrush current.

Claim 20

A method of operating an electric motor, the method comprising the steps of: operating a prime mover proximate the motor to generate dc electrical power; using an inverter to convert the dc power to ac power; supplying the ac power directly to the motor; and controlling an inverter to vary current and frequency of the ac power during startup of the motor, the current being ramped up and then the frequency being ramped up during startup to reduce motor inrush current.

Claim 23

A method of operating an electric motor, the method comprising the steps of: operating a prime mover proximate the motor to generate dc electrical power; using an inverter to convert the dc power to ac power; supplying the ac power directly to the motor; controlling an inverter to vary at least one of current and frequency of the ac power during operation of the motor; and converting backup power to variable frequency ac power when the prime mover fails to generate the dc power.

Claim 24

A method of operating an electric motor, the method comprising the steps of: operating a prime mover proximate the motor to generate dc electrical power; using an inverter to convert the dc power to ac power; supplying the ac power directly to the motor; controlling an inverter to vary at least one of current and frequency of the ac power during operation of the motor; and converting backup power to variable frequency ac power when the prime mover fails to generate the dc power.

Claim 25

A method of operating an electric motor, the method comprising the steps of: operating a prime mover proximate the motor to generate dc electrical power; using an inverter to convert the dc power to ac power; supplying the ac power directly to the motor; controlling an inverter to vary at least one of current and frequency of the ac power during operation of the motor; and ganging other prime movers with the first prime mover.

Claim 26

A method of operating an electric motor, the method comprising the steps of: operating a prime mover proximate the motor to generate dc electrical power; using an inverter to convert the dc power to ac power; supplying the ac power directly to the motor; controlling an inverter to vary at least one of current and frequency of the ac power during operation of the motor; and ganging other prime movers with the first prime mover.

Claim 27

A method of operating an electric motor, the method comprising the steps of: operating a microturbine generator proximate the motor to generate dc electrical power, wherein the microturbine generator is operated using a waste stream for fuel; using an inverter to convert the dc power to ac power; supplying the ac power directly to the motor; and controlling the inverter to vary at least one of current and frequency of the ac power during operation of the motor.

Claim 28

A method of operating an electric motor, the method comprising the steps of: operating a microturbine generator proximate the motor to generate dc electrical power, wherein the microturbine generator is operated using a waste stream for fuel; using an inverter to convert the dc power to ac power; supplying the ac power directly to the motor; and controlling the inverter to vary at least one of current and frequency of the ac power during operation of the motor.

Claim 29

A system comprising: an electric motor; a prime mover for generating dc electrical power; an inverter for converting the dc power to ac power, the ac power being supplied to the electric motor during motor operation; and a controller for controlling the inverter to limit motor current during startup until the motor reaches a predetermined speed; wherein the motor current is limited by ramping up frequency and controlling depth of inverter modulation.

Claim 30

A system comprising: an electric motor; a prime mover for generating dc electrical power; an inverter for converting the dc power to ac power, the ac power being supplied to the electric motor during motor operation; and a controller for controlling the inverter to limit motor current during startup until the motor reaches a predetermined speed; wherein the motor current is limited by ramping up frequency and controlling depth of inverter modulation.