Honeywell International Inc.

Mohamed A Eldery

Robert D Paton

Cristian E Anghel

Zheng Wang

You Zhou

Mitigating the DC content of an AC output from an inverter is important for electrical system reliability. The inverter may be powered by unbalanced DC inputs while still mitigating the DC content of the AC output wavefrom. The present invention provides methods to mitigate the DC content in the output DC voltage by reshaping the PWM reference signals (carrier signals) according to the DC content in such a way that the DC content is canceled. These reshaped PWM reference signals may be, for example, unsymmetrical reference waveforms. Unlike conventional methods for providing an AC voltage from a DC voltage with an inverter, which may result in DC content in the output AC voltage when an unbalanced DC input voltage is supplied, the present invention provides methods for mitigating the DC content in an AC voltage, even if the inverter providing the AC voltage is supplied with unbalanced DC voltage.

Mitigation of unbalanced input DC for inverter applications

A voltage regulator for controlling over-voltage conditions in an electrical generator by rapidly discharging the generator field winding current into a discharge resistor upon the detection of the over-voltage. A field discharge transistor is switched by a soft switching circuit to direct the generator field winding current to the discharge resistor. A hysteresis circuit detects when a point of regulation voltage exceeds a first threshold triggering the discharge of the generator field winding current. The hysteresis circuit also detects when the point of regulation voltage goes below a second lower threshold and triggers the field discharge transistor to bypass the discharge resistor and return to a normal mode.

Fast field discharge for generator over-voltage control

An envelope of a voltage may be extracted using an operator to calculate a position and speed of a rotor. A position and speed sensing method may include supplying voltage to a stator, coupling the voltage into a rotor, extracting an envelope of the voltage using an operator, and calculating a rotor angular position based on the extracted envelope. A position and speed sensing apparatus may include a stator, a rotor and a controller to extract an envelope of a voltage coupled through the rotor into the stator using an operator and to calculate a rotor angular position based on the extracted envelope.

Energy based position and speed self-sensing method and apparatus for synchronous machine

A field discharge circuit may rapidly reduce the field current of a generator, thereby avoiding an overvoltage condition. The field discharge circuit of the present invention may use another storage device, such as a capacitor, to quickly transfer the field current energy thereto and then slowly dissipate the transferred energy after the event (such as removal of a load) has passed. By transferring this energy to a storage device and subsequently slowly discharging this energy through a resistor, electromagnetic interference caused by a conventional resistive discharge can be reduced.

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Mississauga, Canada

Mohamed A Eldery