DEREK A PAICE
Engineers in Palm Harbor, FL

6525951, Feb 25, 2003

Jan 25, 2002

10/054785

Derek Albert Paice - Palm Harbor FL 34685

H02M 500

363154, 363153

In an 18-pulse converter system a three-phase to nine-phase auto-transformer with multiple windings per phase is used to power a nine-phase AC to DC converter. The transformer kVA rating is about 55% of the DC load kW. The basic topology is that of a wye connection, but an active delta path is added to allow circulation of the third harmonics necessary for proper operation. The design requires substantially fewer coils than other three-phase to nine-phase auto-transformers. The voltage ratio can be selected so as to give an average DC output from an 18-pulse converter which is generally the same as that of a conventional three-phase bridge rectifier without a transformer. However, the topology described is also suitable for step up or step down of voltage as required. Where necessary to further reduce high frequency harmonic currents, a three-phase ac line reactor may be connected in series with the source of ac power.

6101113, Aug 8, 2000

Dec 2, 1999

9/453043

Derek A Paice - Palm Harbor FL

H02M 706, H02M 700

363126

In a 12-pulse converter system a 3-phase auto transformer with 4 windings per phase is used to power two 6-pulse converter bridges connected in parallel with a large dc filter capacitor. The transformer rating is typically about 40% of the dc kW load. The voltage ratio is typically 1:1 so that the average dc output of a multi-pulse converter is generally the same as that of a conventional 3-phase bridge rectifier without transformer, however, ac input harmonic currents are greatly reduced. A small single-phase transformer is used to block unwanted circulating currents between the two 6-pulse converters. Where necessary to further reduce high frequency harmonic currents, a 3-phase ac line reactor may be connected in series with the source of ac power. Where a smaller degree of harmonic reduction is acceptable, only 3 windings per phase are required on the transformer and the small single-phase transformer is eliminated by raising the zero-sequence impedance of the auto transformer by means of an additional magnetic path. This method provides a higher zero-sequence impedance compared to a conventional 3-limb magnetic structure used in most 3-phase transformers.

6982884, Jan 3, 2006

Aug 23, 2004

10/924122

Derek Albert Paice - Palm Harbor FL, US

H02M 7/00, H02M 1/12

363 44, 363 39, 363126

An 18-pulse converter is constructed using two, high zero-sequence impedance, phase-shifting autotransformers to parallel two 3-phase bridge converters. A third 3-phase bridge converter is directly connected to the power source. Depending on the DC filtering technique, the kVA rating of each autotransformer is 15 to 22% that of the DC load kW. The method facilitates paralleling of 3-phase bridge converters to reduce system AC line current harmonics, and is suitable for 18, 24, 36, and higher pulse numbers. The minimum number of individual autotransformers required is (n−1), where n is the number of 3-phase bridge converters. Due to the high zero-sequence impedance of the autotransformers, only a small DC load is needed to limit the DC output voltage. AC line reactance may be included in series with each converter, or in the 3-phase AC power source, to further reduce AC line current harmonics.

7719858, May 18, 2010

May 4, 2009

12/387440

Derek Albert Paice - Palm Harbor FL, US

H02M 7/48

363 5, 363 64, 363129

A polygon connected three-phase autotransformer using nine windings per phase provides a reduced power rating fifteen-phase power source suitable for 30-pulse AC to DC power converters. The windings are selected and connected in a manner that accommodates zero-sequence currents, such as the third harmonic, and minimizes total kVA rating. When the autotransformer is used to power a 15-phase AC to DC converter its kVA rating is typically less than 51% of the DC load kW. AC line current distortion is negligible and can satisfy the most exacting practical harmonic specifications. Additional isolated windings can provide means for the invention to operate as an efficient double-wound transformer.

7750782, Jul 6, 2010

Feb 20, 2009

12/378796

Derek Albert Paice - Palm Harbor FL, US

H01F 30/12

336 12, 363148, 363153

A polygon connected three-phase autotransformer using six windings per phase provides a reduced power rating nine-phase power source suitable for 18-pulse AC to DC power converters. The windings are selected and connected in a manner that controls harmonic currents and minimizes total kVA rating. When the autotransformer is used to power a nine-phase AC to DC converter its kVA rating is typically less than 48% of the DC load kW. Additional isolated windings can provide means for the invention to operate as an efficient double-wound transformer.

5781428, Jul 14, 1998

Mar 3, 1997

8/810482

Derek A. Paice - Palm Harbor FL

H02M 700, H02M 112, H02M 706

363126

In a multi-pulse converter system a three-phase transformer with tapped wye-connected primary winding and isolated delta-connected secondary winding is used to power two 6-pulse converter bridges connected in series to give 12-pulse operation. The transformer equivalent kVA rating is a fraction, typically less than 60%, of the total dc power. By adjusting the tapping on the wye-connected primary winding the converter dc output voltage is readily adjusted to provide higher or lower dc voltage than is attainable by a three-phase 6-pulse converter. By these means a reliable and versatile 12-pulse converter is obtained which, without additional hardware, gives excellent performance in the face of practical power sources which may incorporate voltage unbalance and pre-existing harmonic voltages.

4719398, Jan 12, 1988

Jun 9, 1986

6/871979

Derek A. Paice - Palm Harbor FL

Westinghouse Electric Corp. - Pittsburgh PA

H02P 126

318778

A variable frequency adjustable speed motor drive allows restart of a spinning induction motor by initially increasing the frequency of the associated inverter while keeping the DC voltage source thereof low, then by decreasing the frequency of the inverter while monitoring the effective motor impedance V. sub. DC /I. sub. DC or V. sub. AC /I. sub. AC until the latter jumps at an initial level indicating matching of the frequency with the motor spinning speed. Thereafter, the DC voltage is restored in magnitude and the inverter is increased in frequency to match the desired motor speed.

5455759, Oct 3, 1995

Jun 24, 1994

8/264922

Derek A. Paice - Palm Harbor FL

H02M 700, H02M 706

363126

In 12-pulse and 18-pulse AC/DC converter systems a single wye connected auto transformer using appropriate segments of voltage from each phase connected in fork fashion is used to develop 6-phase and 9-phase voltages in a symmetrical manner such that inherent compensation is made for the dc converter output voltage to be within 4. 2% of that of a 6-pulse converter. Additional design adjustments for step-up or step-down of voltage can be made without compromising the transformer symmetry. An unconnected but closed delta winding provides a path in which third harmonic currents, and multiples thereof can flow.

4698739, Oct 6, 1987

Nov 7, 1986

6/928145

Derek A. Paice - Palm Harbor FL

Westinghouse Electric Corp. - Pittsburgh PA

H02M 700

363 71

The present invention relates to an AC motor drive including two sets of inverters, wherein one transformer is converted on the output of one of the two inverters, the output of the transformer being connected in series with the output of the other inverter.

5148357, Sep 15, 1992

Oct 7, 1991

7/772504

Derek A. Paice - Palm Harbor FL

Westinghouse Electric Corp. - Pittsburgh PA

H02M 700, H02M 706

363 5

A 12-pulse converter of lower rating and minimal current harmonics is obtained with an auto-connected regular hexagon transformer including a delta winding in its center.