Charles W Edwards

56420030, Jun 24, 1997

Aug 22, 1995

8/517897

Charles W. Edwards - Monroeville PA
Nicholas C. Abi-Samra - Irvine CA

Electric Power Research Institute, Inc. - Palo Alto CA

H02M 112

307 64

A power switching apparatus includes a positive-sequence fundamental signal magnitude detector. The positive-sequence fundamental signal magnitude detector derives a positive-sequence fundamental signal from a three-phase voltage signal carried by a power line; it also generates a switch firing command when the positive-sequence fundamental signal exceeds a predetermined threshold value indicative of a fault condition on the power line. The power switching apparatus also includes a solid state switch connected to the power line and the positive-sequence fundamental signal magnitude detector. The solid state switch bloch power on the power line in response to the switch firing command.

46740252, Jun 16, 1987

Jun 5, 1986

6/871047

Charles W. Edwards - Monroeville PA

Westinghouse Electric Corp. - Pittsburgh PA

H02M 112

363 71

In a multi-inverter system, inverters in series are swapped around in order to eliminate regenerative power due to phase difference between consecutive inverters in series.

46740244, Jun 16, 1987

Jun 5, 1986

6/871048

Derek A. Paice - Palm Harbor FL
Charles W. Edwards - Monroeville PA

Westinghouse Electric Corp. - Pittsburgh PA

H02M 7515

363 71

Low voltage GTO inverter modules are combined to form a high-voltage multi-inverter system by connecting standard modules in a string with isolated DC links. Modular construction is arranged for building multiphase systems. Voltage control is effected by controlling selected modules on the DC sides, or by pulse-width modulation of the inverter of a selected module.

46022015, Jul 22, 1986

Oct 9, 1985

6/786163

Charles W. Edwards - Monroeville PA

Westinghouse Electric Corp. - Pittsburgh PA

H02D 540

318811

A pulse-width-modulated motor drive includes means for the derivation of a signal representative of the torque by sensing the DC-link current directly, or indirectly, and by dividing the sensed signal by the modulation index of the motor drive to obtain proportionality through the duty-cycle long range succession.

49841483, Jan 8, 1991

May 29, 1990

7/529843

Charles W. Edwards - Monroeville PA

Westinghouse Electric Corp. - Pittsburgh PA

H02M 324

363 95

A two-phase bang-bang current control synchronizer for synchronizing two current streams which pass within a hysteresis controller. Synchronization occurs by summing a fixed hysteresis threshold voltage from a master chopper and a sawtooth wave voltage corresponding to a synchronization and outputting a summed signal to an integrator controller which integrated the summed signal and outputs an intergrates signal. A synchronization circuit receives the integrated signal and generates a sawtooth waveform corresponding to an average value of the fixed hysteresis threshold voltage. The sawtooth waveform is fed to the slave chopper and synchronizes the master chopper and the slave chopper.

50102915, Apr 23, 1991

May 29, 1990

7/529844

Charles W. Edwards - Monroeville PA

Westinghouse Electric Corp. - Pittsburgh PA

H02M 744

323222

A single quadrant chopper timing control circuit is used with unidirectional power flow chopper arrangements in a power inverter to maintain current oscillation between positive and negative threshold levels of a hysteresis controller. The single quadrant chopper timing control circuit creates a mimic current when the current in the power inverter becomes zero or less. The mimic current allows the unidirectional power arrangement to continue oscillating so that there is little or no discontinuity in the timing. The device will continue to operate and provide a high bandwidth to ensure that the device will function during an overload or load dump condition.

53592751, Oct 25, 1994

Oct 30, 1992

7/969081

Charles W. Edwards - Monroeville PA

Electric Power Research Institute, Inc. - Palo Alto CA

G05F 170

323207

An apparatus and method of constructing a sinusoidal output signal corresponding to a predetermined harmonic component of a sinusoidal input signal is described. The input signal is multiplied by a specified harmonic component of cosine and sine reference signals to divide it into direct and quadrature signals. The direct and quadrature signals are proportional to the amplitude of the specified harmonic component of the reference signals at the specified phase. Each cycle of the direct and quadrature signals is sampled a number of times to form direct and quadrature signal segments. The direct and quadrature signal segments are respectively placed in direct and quadrature circular buffers. Each circular buffer includes a number of formerly sampled segments. Before adding a new segment, the oldest segment in the buffer is dropped.

59841737, Nov 16, 1999

Feb 2, 1998

9/017034

Charles Wood Edwards - Monroeville PA

Siemens Power Transmission & Distribution, LLC - Wendell NC

G05F 170
H02M 112

232207

Apparatus for injection voltage compensation in series into an electric power line includes an inverter or other controlled voltage source which wye connects the secondary windings of a three-phase transformer to the load end of the electric power line. The transformer, which could already be present for meeting load requirements, has its primary winding connected to the source end of the electric power line and sustains the saturation currents rather than the inverter in response to faults on the source side of the transformer. Preferably, a three-phase inverter with a common dc link is used. For active power line conditioner (APLC) action, a second, also preferably a three-phase, inverter is connected in parallel to the load end of the electric power line and to the common dc link. This parallel inverter provides harmonic and reactive power compensation and also supplies the real power requirements of the wye connection inverter.