Patent application number | Description | Published |
20080315822 | Rotor position detection at standstill and low speeds using a low power permanent magnet machine - For a multiphase alternating current (AC) wound field synchronous machine (WFSM) that has a stator with a selected number of poles, the WFSM having an associated exciter and multiphase AC permanent magnet machine (PMM) directly coupled to the WFSM, a method of sensing the position of a rotor in the WFSM comprises the steps of: configuring a stator for the PMM to have a number of poles that is a sub-multiple of the selected number of WFSM stator poles; configuring a rotor for the PMM to have high saliency; applying multiphase AC power of a selected frequency to the PMM stator: detecting at least one set of stator harmonic currents of the multiphase AC power resulting from the rotor saliency; converting the detected PMM harmonic stator currents from their multiphase coordinates to αβ coordinates; rotating the converted PMM stator currents into a reference frame for at least one selected harmonic to generate αβ coordinate harmonic current vectors; and estimating the position of the WFSM rotor based on the values of the αβ coordinate harmonic current vectors in the selected harmonic reference frame. | 12-25-2008 |
20090008993 | Hybrid electromechanical power transfer system - An electromechanical power transfer system that transfers power between a prime mover and a combination of multiphase alternating current (AC) and direct current (DC) electrical power systems, comprises: a dynamoelectric machine that has a rotor assembly coupled to the prime mover, a main stator with a multiphase alternating current (AC) winding coupled to a main stator bus and a control coil with a winding that varies the output of the main stator with the application of control coil current; a matrix converter coupled to the main stator bus for converting AC on the main stator bus to AC of a desired electrical frequency and potential on an AC system bus; an active rectifier coupled to the main stator bus for converting AC on the main stator bus to DC of a desired potential on a DC bus; and a system control unit for generating the control coil current with a level that regulates the output of the main stator on the main stator bus, controlling the output of the matrix converter to regulate the output of the AC system bus and controlling the output of the active rectifier to regulate the output of the DC bus. | 01-08-2009 |
20090009129 | Active damping for synchronous generator torsional oscillations - A generator control unit (GCU) provides active damping of a synchronous generator by monitoring the speed of the synchronous generator and detecting oscillations in the monitored speed. The oscillations are indicative of torsional oscillations within the mechanical drivetrain including the synchronous generator or generators. In response to detected oscillations in the monitored speed, the GCU generates a varying set-point value that is used to control the excitation voltage provided to the synchronous generator. Varying the excitation voltage provided to the synchronous generator causes a variation in synchronous generator torque. By selectively varying the torque in the synchronous generator, the GCU provides active damping in the synchronous generator that decreases or dampens the torsional oscillations. | 01-08-2009 |
20090021208 | On-line measurement of an induction machine's rotor time constant by small signal d-axis current injection - A controller continually updates rotor time constant estimation of an induction machine by interrogating the induction machine with a small signal oscillation and monitoring the response. The small signal oscillation is injected onto the d-axis current command signal, and is generated at a frequency that represents the most recent estimate of the rotor time constant (i.e., rotor time constant equal the inverse of the frequency). The controller monitors rotor flux generated in response to the small signal oscillation, and updates the most recent estimate of the rotor time constant based on the monitored rotor flux. This process is repeated continuously to allow for the continuous updating of the rotor time constant. | 01-22-2009 |
20090045292 | ENGINE HAVING POWER BUS FAULT SHORT CIRCUIT CONTROL WITH A DISCONNECTION SWITCH - An aircraft electrical system comprises a generator to be driven as part of a gas turbine engine. The generator supplies electrical power to a plurality of accessories associated with the gas turbine engine, and to an aircraft power bus in parallel to the supply to the accessories. A control detects a short circuit on the aircraft power bus. When a short circuit is detected on the aircraft power bus, a switch is driven open to disconnect the aircraft power bus from the generator. In this manner, the power will continue to be delivered to the plurality of accessories. In a separate feature, a control voltage is provided by an auxiliary permanent magnet generator to a voltage regulator for the main generator. | 02-19-2009 |
20090045293 | GENERATOR FOR GAS TURBINE ENGINE HAVING DC BUS FAULT SHORT CIRCUIT CONTROL USING A BATTERY - An aircraft electrical system comprises a generator to be driven as part of a gas turbine engine. The generator supplies electrical power to a plurality of accessories associated with the gas turbine engine, and to an aircraft DC bus in parallel to the supply to the accessories. A battery supplies voltage to a control circuit for the generator through a selectively opened and closed switch. A control detects a short circuit on the aircraft DC bus. The battery switch allows power from the battery to flow to provide control voltage for the generator when the control detects a short circuit on the aircraft DC bus. | 02-19-2009 |
20090091132 | STARTER/GENERATOR SYSTEM WITH CONTROL TO ADDRESS A VOLTAGE RISE - A control circuit for a generator has a control function that monitors the voltage across a bus capacitor. The circuit delivers excess voltage back to associated stator windings if an unduly high voltage is detected across the bus capacitor. | 04-09-2009 |
20090153083 | METHOD OF OPERATING A BRUSHLESS MOTOR WHEREIN OPEN LOOP AND CLOSED LOOP CONTROLLERS UTILIZE DIFFERENT COMMUTATION METHODS - A motor control is provided with both open loop and closed loop controllers. The open loop and closed loop controllers provide commutation signals back to gate drives for an inverter, wherein the commutation signals utilize sinusoidal signals in open loop control, and utilize six step commutation in closed loop control. | 06-18-2009 |
20090167256 | System and method for suppressing DC link voltage buildup due to generator armature reaction - A controller employed in conjunction with a synchronous generator monitors the output voltage of the generator. The controller employs the monitored output voltage as feedback that is used to control the excitation provided to an exciter field winding. In addition, the controller applies a control loop to the monitored output voltage that detects and modifies voltage ripple signals within the monitored output voltage to generate a compensated signal that is used to control the excitation to the exciter field winding. In particular, by detecting and modifying voltage ripple signals within the monitored output voltage, the controller is able to counteract armature reaction voltage ripples caused by unbalanced short-circuit faults, thereby preventing the build-up of voltage on the DC link. | 07-02-2009 |
20090167257 | SHORTED ROTATING DIODE DETECTION AND PROTECTION - An electric generator with a rotating diode fault detection device built in that operates by comparing a voltage buildup across the exciter DC supply with a preset threshold value and determining if a fault condition is present based on the comparison. | 07-02-2009 |
20090261586 | Dual Channel Power Generation System - A dual channel power generation system comprises: a prime mover; a permanent magnet (PM) dynamoelectric machine that has a PM rotor coupled to the prime mover, two multiphase alternating current (AC) stators that develop electromotive force (EMF) in response to rotation of the PM rotor due to the magnetic flux linkage between the PM rotor and the stators, two control coils that each change the magnetic flux linkage of a respective stator in response to the level of a control current that passes through the control coil; a multiphase AC rectifier for each stator that receives AC power from its respective stator to supply DC power on a respective rectifier bus; a current feedback loop for each rectifier bus; a voltage feedback loop for each rectifier bus; a load-sharing controller responsive to both current feedback loops to develop a voltage regulator reference signal for each rectifier bus that is representative of the value of voltage that its corresponding stator should produce to maintain equal values of current for both rectifier buses; and a voltage regulator for each rectifier bus responsive to its respective voltage feedback loop and voltage regulator reference signal to produce the control current for its respective control coil that changes the magnetic flux linkage of its respective stator to maintain the value of voltage that its corresponding stator should produce to maintain equal values of current for both rectifier buses. | 10-22-2009 |
20100060288 | METHOD OF DETECTING A SUSTAINED PARALLEL SOURCE CONDITION - A method of detecting a parallel source condition includes calculating a reactive power, comparing the reactive power to a predetermined threshold, and determining a parallel source condition in response to the reactive power exceeding the predetermined threshold. | 03-11-2010 |
20100072930 | NEGATIVE SEQUENCE CARRIER SIGNAL CONTROLLER - A negative sequence feedback circuit is connected to monitor and minimize unbalances in a high-frequency ac carrier signal provided to a motor/load for the purpose of detecting rotor position. The negative sequence feedback circuit detects unbalances in the high-frequency ac carrier signal and generates negative sequence feedback. The feedback is combined with command signals used to generate the high-frequency ac carrier signal, and the combination of the command signals with the negative sequence feedback is provided to an inverter for generation of the high-frequency ac carrier signal, wherein the negative sequence feedback reduces unbalances in the resulting high-frequency ac carrier signal such that a balanced high-frequency carrier signal is provided to the motor/load. | 03-25-2010 |
20100175478 | Torque Oscillation Monitoring - A method of detecting and monitoring torsional oscillation in a mechanical coupling between a prime mover and a multiphase alternating current (AC) electrical generator, comprises the steps of: detecting in at least one received signal variations that are indicative of changes in the rotational speed of the electrical generator; extracting information from the detected variations that are indicative of torsional oscillation to produce a torsional oscillation signal that has information relating to at least the amplitude of the torsional oscillation; and monitoring the torsional oscillation signal to determine the presence and severity of the torsional oscillation in the mechanical coupling. | 07-15-2010 |
20100253294 | STARTER VOLTAGE REDUCING SYNCHRONOUS MACHINE - An electric power generation system has a synchronous machine, a starter excitation source and an exciter field driver. The starter excitation source is connected to the synchronous machine via multiple phase connections, and the exciter field driver is connected to the synchronous machine via a portion of the same phase connections. At least one of the phase connections is connected to each other phase connection via a transient voltage suppressor. | 10-07-2010 |
20120182648 | OVERVOLTAGE LIMITER IN AN AIRCRAFT ELECTRICAL POWER GENERATION SYSTEM - A generator includes a permanent magnet generator, an exciter and a main generator mounted for rotation on a shaft. The main generator is configured to produce a voltage output. A generator control unit includes a circuit configured to provide current from the permanent magnet generator to the exciter. A switch is provided in the circuit and is configured to change between open and closed conditions. The switch is configured to flow current in the circuit in the closed condition and interrupt current flow in the open condition. An overvoltage limit controller is programmed to determine an amount of overvoltage of the output voltage exceeding a desired voltage. Either a fixed reference threshold is used or a reference threshold voltage is calculated based upon the duration in over voltage condition, and the switch is modulated between the open and closed conditions according to error between the actual output voltage and the reference threshold voltage to limit the output voltage to the desired reference threshold voltage. | 07-19-2012 |
20130003231 | OVERVOLTAGE PREVENTION IN AN AIRCRAFT ELECTRICAL POWER GENERATION SYSTEM - An example method of detecting a generator overvoltage condition includes predicting a primary control current to provide a predicted control current, monitoring the primary control current, and detecting a generator overvoltage condition based on a comparison of the predicted control current to the primary control current. The method interrupts the primary control current based on the comparing. | 01-03-2013 |
20130182354 | OVERVOLTAGE PROTECTION DURING GCU FAILURE - An overvoltage protection system for a power generating system includes a generator control relay (GCR) controlling a conduction path through a generator exciter field, a flyback impedance in parallel communication with the generator exciter field, the flyback impedance configured to dissipate energy from the generator exciter field in response to opening of the conduction path, a gate drive configured to open and close the GCR, and an overvoltage prevention unit in signal communication with the gate drive, the overvoltage prevention unit configured to monitor a voltage and a current associated with the generator and selectively open and close the conduction path in response to the monitored voltage and current. | 07-18-2013 |
20130271878 | AUTOMATIC FAULT ISOLATION METHODOLOGY - A method and system for responding to a fast trip protective element trip in a generator system that re-excites the generator when a fast trip protection element trips and determines whether the generator immediately retrips the fast trip protection element, thereby determining whether a fault is located in the generator or in an attached load. If it is determined that the fault is located in the load, the system re-excites and reconnects the load after disabling the fast trip protection element for a specified period to allow for the load to clear its fault. | 10-17-2013 |