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US 7,459,877 B2Granted
Solid state reversing AC motor starter with DC power source
AssigneeWestinghouse Electric Corp.
InventorBruce M. Cook
Life of this patent
Estimating the term…
Abstract
A solid state reversing AC motor starter that employs a DC power source and a power bridge employing insulated gate bipolar transistors that provide an ungrounded three phase AC output. The AC output is connected to the power input of the motor starter, which requires simultaneous RUN and Directional Commands to initiate valve actuation.
Claims16
A solid state AC motor starter with DC power source comprising:
- a DC input;
- a capacitor input filter connected across the DC input;
- a power bridge comprising:
- at least six gates respectively having a gate output individually switchable between an on and off state;
- a power bridge output having three phases, each phase of the bridge output being connected to respective combinations of the gate outputs;
- a capacitor filter connected across each phase of the three phase output;
- an AC power logic circuit for controlling the timing of the switching on and off of the states of the respective gates at a higher frequency than the desired bridge output and varying the duration of the on state of the respective gates so that an output voltage of the three phases can be made to approximate a sine wave using pulse width modulation;
- and
- an AC motor starter circuit having an AC power input connected to the power bridge output;
- wherein the AC motor starter circuit includes a motor starter logic circuit that has an open signal input, a close signal input and a run signal input wherein a run signal and either an open signal or a close signal must be present at the corresponding run signal input and open signal input or close signal input for the motor starter circuit to be in an on state to actuate a motor.
7 more elements
A solid state AC motor starter with DC power source comprising:
- a DC input;
- a capacitor input filter connected across the DC input;
- a power bridge comprising:
- at least six gates respectively having a gate output individually switchable between an on and off state;
- a power bridge output having three phases, each phase of the bridge output being connected to respective combinations of the gate outputs;
- a capacitor filter connected across each phase of the three phase output;
- an AC power logic circuit for controlling the timing of the switching on and off of the states of the respective gates at a higher frequency than the desired bridge output and varying the duration of the on state of the respective gates so that an output voltage of the three phases can be made to approximate a sine wave using pulse width modulation;
- and
- an AC motor starter circuit having an AC power input connected to the power bridge output;
- wherein the AC power logic circuit controls the power bridge to provide a reduced voltage output upon startup of the AC motor starter circuit for a preselected period of time after which a full power output is provided to the AC motor starter circuit AC power input.
7 more elements
Dependencies are inferred from the claim text.