William G. Dunford

BACKGROUND

AREAS OF INTEREST

Power electronics, particularly applied to photovoltaic applications and alternative energy systems. Pump drives, traction drives, high power converters. Application of microcontrollers and DSP controllers. Distributed Energy Systems. Low power converters.

SOME MAJOR RESEARCH CONTRACTS

CANADIAN CABLE LABS (ROGERS CABLE) - A Battery Charge Equalizing Circuit.
BC HYDRO - A Photovoltaic Powered Water Circulator.
Canadian Space Agency - Battery Management System
Design and construction of a 250 kVA IGBT based inverter system.



OTHER INDUSTRIAL COLLABORATION

BC Science Council GREAT and NSERC IPS scholarships have been awarded for graduate students to work with the following local companies:


STATPOWER  (now part of Xantrex) - Power supply design

XANTREX - High power converter design


Alpha Technologies - Power converter control

Some projects funded from other sources

Powertech Labs/BC Hydro - DC distribution study


Auto 21 (Network of Centres of Excellence in automotive applications) Regenerative drive including machine design


Exercise machine controller


Magnetic levitation system for wafer transportation.


Stepper motor controller


Replacement of hydraulic control by variable speed ac drive in manufacturing process.


Linear generator study.

High speed alternator control.


Robot controller


Tunelling machine drive study


Off line switching supply.


OTHER SUPPORT

The Kaiser Educational Foundation has been very generous in supporting facilities in the power electronics area. This has included student prizes and the means of purchasing research equipment. In a new building under construction the Alpha Technologies laboratory will house future work in this area

Publications

1.       Garabandic G, Dunford W G, Edmunds M, “Zero Voltage, Zero Current Switching in Full Bridge PWM Converters Using the Interwinding Capacitance”, IEEE Transaction on Power Electronics, Vol 14, No 2, pp 343 – 349, March 1999.

2.       Wang, J., Dunford, W.G., Mauch, K., "Analysis of Ripple Free Input Inductor Current Boost Converter with Discontinuous Conduction Characteristics", IEEE Transactions on Power Electronics, Vol. 12, No. 4, July 1997, pp. 684-694.

3.       Barnard, J.M., van Wyk, J.D., Dunford, W.G., "Battery Operated Wheelchairs, Using 3--Phase Cage Rotor Induction Machines & PWM Inverters", European Power Electronics Journal Vol. 4. No. 1, March 1994, pp. 15--19.

4.       Dunford, W.G., van Wyk, J.D., "Subharmonic Components in an Asynchronous PWM Scheme with Digital Pulse Modulation", Trans. South African Inst. Elec. Eng., vol. 84, no. 3, September 1993, pp. 210--217.

5.       Dunford, W.G., van Wyk, J.D., "Harmonic Imbalance in Asynchronous PWM Schemes", IEEE Transactions on Power Electronics, Vol. 17, No. 3, July 1992, pp. 480--486.

6.       Salazar, A.O., Dunford, W.G., Stephan, R., Watanabe, E., "A Magnetic Bearing System Using Capacitive Sensors for Position Measurement", IEEE Transactions on Magnetics Vol. 26, No. 5, Sept. 1990, pp. 2541- 2543.

7.       Schultz, J., van Wyk, J.D., Dunford, W.G., Prest, R.B., Landy, C.F., "An Inverter and Induction Motor Traction Drive for Underground Locomotives", Elektrische Bahnen (e.b.) Vol. 88, No. 3, 1990, pp. 145--148.

8.       Dubey, G.K., Dunford, W.G., "Chopper Control of a Compound Motor", International Journal of Energy Systems, Vol. 10, No. 1, 1990, pp. 1--5.

9.       Lobbezoo, A.M., Bruijn, P.M., Davies, M.S., Dunford, W.G., Lawrence, P.D., van Naute Lemke, H.R., "Robot Control Using Adaptive Transformations", IEEE J. of Robotics & Automation, Vol. 4, No. 1, Feb. 1988, pp. 104--107.

10.   Ward, P.R.B., Dunford, W.G., Pulfrey, D.L., "Performance of Small Progressive Cavity Pumps with Solar Power", Can. J. Civ. Eng., 1987, Vol. 14, pp. 284--287.

11.   Peabody, F., Nyberg, C., Dunford, W.G., "The Use of a Spreadsheet Program to Design Motors on a Personal Computer", IEEE Industrial Applications Soc. Trans. Vol. 1A-23, No. 3, May/June 1987, pp. 520--525. (Awarded second prize at IAS conference.)

12.   Pulfrey, D.L., Ward, P.R.B., Dunford, W.G., "A Photovoltaic Powered System for Medium Head Pumping", Solar Energy, Vol. 38, No. 4, 1987, pp. 255--265.

13.   Mirbod, S.A., Dunford, W.G., "A Capacitor Bank Charger Using a High Frequency Link Resonant Circuit", Proc. IEE Vol. 132, Pt. B, No. 6, Nov. 1985, pp. 327--334.

14.   Liu, G., Dunford, W.G., "Photovoltaic Array Simulation", 1985, IEEE Pwr. Electronics Specialists Conf./European Space Agency J., pp. 145--153.

15.   Dewan, S.B., Dunford, W.G., "A Microprocessor-Based Controller for a Three-Phase Controlled Rectifier Bridge", IEEE Industrial Applications Soc. Trans., Vol. 1A-19, No. 1, Jan./Feb. 1983, pp. 113--119.

16.   Bonert, R., Dunford, W.G., "Dynamic Response of Phase Controlled Rectifiers with Digital and Microprocessor Based Gating Circuits", 1982, IEEE, PESC pp. 180--184.

17.   Dunford, W.G., Dewan, S.B., "Design of a Control Circuit for a Two Quadrant Chopper based on the Motorola M6800 Microprocessor", IEEE, Industrial Applications Soc. Trans., Vol. 1A-16, No. 4, July/Aug. 1980, pp. 495--501.

18.     Dewan, S.B., Dunford, W.G., "Improved Power Factor Operation of a Single Phase Controlled Rectifier Bridge through Modified Gating", 1980, IEEE PESC pp. 357--366.

19. Xiao W., Dunford W.G., “ A Modified Adaptive Hill Climbing MPPT Method for Photovoltaic Power Systems”, IEEE PESC 2004, Aachen,
20. Xiao W., Dunford W.G., “A Novel Modeling Method for Photovoltaic Cells”, IEEE PESC 2004, Aachen,
21. Swingler A D, Dunford W G, “Development of a Bi-Directional DC-DC Converter for Inverter/Charger Applications with Consideration Paid to Large Signal Operation and Quasi Linear Digital Control”, IEEE PESC 2002,Cairns Australia, pp 961 - 966.
22. Carlton D, Dunford W G, “Skip-Cycle Modulation of Three-Phase Boost Power Factor Correction Circuits Operating in Discontinuous Current Mode”, IEEE PESC 2001, Vancouver, pp 1001 – 1006.
23. Carlton D, Dunford W G, “Multi-Level, Uni- Directional AC-DC Converters, a Cost Effective Alternative to Bi-Directional Converters”, IEEE PESC 2001, Vancouver, pp 1911 – 1916.
24. Carlton, D.; Dunford, W.G.; Edmunds, M.  “'Delta-Delta' three-phase boost power factor correction circuit operating in discontinuous conduction mode” IEEE IAS,  1999, Phoenix, Vol 4, pp 2497 – 2503.
25. Garabandic, D.; Dunford, W.G.; Kuzmanovic, M.. “A class of zero-voltage-zero-current switching full bridge PWM converters with a parallel capacitor for primary current reset”, Electrical and Computer Engineering, 1999 IEEE Canadian Conference on Electrical and Computer Engineering , Edmonton, Volume: 1, pp 565 – 570.
26. Carlton D, Dunford W G, Edmunds M, “Application of Quasi Tri Directional Switch in Three phase Power Factor Correction Circuits”, HFPC 1999, Chicago, vol 14, pp 257 – 266.
27. Carlton, D.; Dunford, W.G.; Edmunds, M., “Average current space vector technique for the analysis of three-phase power factor correction circuits operating in discontinuous conduction mode”, Electrical and Computer Engineering, 1999 IEEE Canadian Conference on Electrical and Computer Engineering, Volume: 2 , 1999, Edmonton,  pp 1136 – 1141.
28. Carlton, D.; Dunford, W.G.; Edmunds, M, “Continuous conduction mode operation of a three-phase power factor correction circuit with quasi tri-directional switches”, IEEE PESC 1999, Vol 1, pp 205 – 210.
29. Carlton, D.; Dunford, W.G.; Edmunds, M. “'Deltafly' three-phase boost power factor correction circuit operating  in discontinuous conduction mode” IEEE ISIE  1999, Taipei, Vol 2, pp 533 – 538.
30. Carlton, D.; Dunford, W.G.; Edmunds, M., “Harmonic reduction in the 3-phase 3-switches boost-delta power factor correction circuit operating in discontinuous conduction mode”, International Telecommunications Energy Conference INTELEC 1998, Copenhagen,  pp 483 – 490.
31. Carlton D, Dunford W, Edmunds M, “SEPIC 3 Phase, 3 Switch Power Factor Correction Circuit Operating in Discontinuous Mode”, IEEE ISIE 1998,  Vol 1, pp 81 –  86.
32. Cassagne, M.-P., Capel, A., Picart, G., Gave, G., Willmann, P., Dudley, G., Hendel, B., Chattelan, B., and Dunford, W.G., “Comparison Between ELAN Test Results and an Improved Zimmerman Model”, European Space Agency Space Power Conference, Tarragona, September 1998.
33. Garabandic, D., Dunford, W.G., Edmunds, M., “Zero-Voltage-Zero-Current Switching in High-Output-Voltage Phase Shifted DC/DC Converters Using the Interwinding Capacitance”, IEEE PESC 98, Japan, June 1998, Vol 2,  pp. 955-960.*
34. Garabandic, D., Dunford, W.G., Petrovic, T., “Robust Decentralized Control of Parallel DC/DC Converters”, IEEE PESC 98, Fukuoka, Japan, June 1998, pp. 911-915.
35. Wang, J., Dunford, W.G., Mauch K., “Some Novel Four-Quadrant DC-DC Converters”, IEEE PESC 98, Japan, June 1998, pp. 1775-1782.
36. Garabandic, D., Kuzmanovic, M., and Dunford, W., “A Low-loss 2D-C-L-R Resonant Recovery Snubber for Single-Switch Soft-Switching Boost DC/DC Converters”, in Proc. Of IEEE CCECE’98, May 1998, Vol 2, pp. 858-861.
37. Garabandic, D., Edmunds, M., Dunford, W.G., “Snubbers for the Distributed Interwinding Capacitance in High-Output-Voltage Converters”,  IEEE APEC 98, Anaheim, CA, February 1998, Vol 2, pp 846 - 849.
38. Cretu, D., Dunford, W.G., Edmunds, M., “Universal Input 3-Phase, 3-Switch Power Factor Correction Circuit Operating in Discontinuous Conduction Mode”, IEEE INTELEC, 1997, pp. 475-482.
39. Wang, J., Dunford, W.G., Mauch, K., "Analysis of Modified Buck Converters Operating in Continuous conduction Mode", IEEE PESC, 1997, pp. 269-276.
40. Wang, J., Dunford, W.G., Mauch, K. "Synthesis of Two lnductor DC-DC Converters", IEEE PESC, 1997, Vol 2, pp. 1367-1373.
41. Ward, P.R.B., Yassien, H.A., Ashley, K.I., Dunford, W.G., Welder, L., "Liquid Fertilizer Injection for Rehabilitation of Salmon Runs", IAHR XXVII Congress, San Francisco, 1997 (in press).
42. Cretu, D., Dunford, W.G., Garabandic, G., Edmunds, M., "Single Stage DC-DC Converter for High Current, High Power Application", IEEE APEC 1997 (pp. 617--622).
43. Cretu, D., Dunford, W.G., Edmunds, M., "A Comparison of Three Phase Resonant and PWM Saturable Converters for High Current, High Power Applications", IEEE APEC 1997 (pp. 631--637).
44. Garabandic, D., Dunford, W.G., Edmunds, M., "Primary Saturable Inductor for High Power Zero Voltage Switching DC-DC Converter with IGBTs IEEE APEC 1997 (pp. 944--947).
45. Bond, E, Wang J, Dunford, W., Mauch K, "A Simple Spreadsheet-based Converter Performance Model Reduces Analysis and Design Time", IEEE, IAS Conference, 1996, pp. 891--897.
46. Wang, J. Dunford, W., Mauch K., "A Comparison of a Modified Boost Converter with Continuous Inductor Current Mode and Ripple Free Input Current with Conventional converters", IEEE IAS Conference, 1996, pp. 878--885.
47. Wang, J., Dunford, W., Mauch, K., "A Comparison between Two Proposed Boost Topologies and Conventional Topologies for Power Factor Correction", IEEE IAS Conference, 1996, pp. 1210--1217.
48. Wang, J., Dunford, W., Mauch, K., "A Comparison between some Proposed Boost Topologies and Conventional Topologies in Discontinuous Inductor Current Mode", IEEE IECON, 1996, pp. 1524--1529.
49. Wang, J., Dunford, W., Mauch, K., " A Fixed Frequency, Fixed Duty Cycle Boost Converter with Ripple Free Input Inductor Current for Unity Power Factor Operation", IEEE PESC, 1996, pp. 1177--1183.
50. Wang, J., Dunford, W., Mauch, K., "Modified Boost with Continuous Inductor Current Mode and Ripple Free Input Current", IEEE PESC, 1996, pp. 390--396.
51. Wang, J., Dunford, W., Mauch, K., "Ripple-free Input Current Boost Converter with Discontinuous Inductor Current Mode", High Frequency Power Conference, 1996, pp. 211--224.
52. Wang, J., Dunford, W., Mauch, K., "Design of Zero Current Switching, Fixed Frequency Boost and Buck Converters  with Coupled Inductors", IEEE PESC, Atlanta, June 1995, Vol 1, pp. 273 - 279.
53. Wang, J. Dunford, N., Natarajan, T., "Analysis and Optimum Design of an Integrated Nondissipative Subber for Push-Pull Type Converter", IPEC, Yokohama, April 1995.
54. Le Pocher, H., Laszlo, C.A., Dunford, W.G., "Finite Element Analysis of Magnetic Stimulation of the Motor Cortex", Canadian Medical & Biological Engineering Conference, Vancouver, May 1994.
55.  Dunford, W.G., Khan-Ngern, W., van Wyk, J.D., "Analysis and Implementation of a Discontinuous Pulse Width Modulation Scheme", IEEE APEC, Orlando, Feb. 94, pp. 128--134.
56. Khan-Ngern W., Dunford, W.G., "The Implementation of a New Switching Strategy for PWM Inverters Using IGBTs", UPEC Conference, Stafford, Sept. 93, pp. 573--576.
57. Al-Mawsawi, S.A., Dunford, W.G., Coonick, A., "Comparison of HSPICE and EMTP for Power Electronic Analysis", UPEC Conference, Stafford, Sept. 93, vol. 2. pp. 772--775.
58. Salazar, A.O., Stephan R., Dunford, W.G., "Performance of a Bearingless Induction Motor", IEEE Applied Control Conference, Brazil, Sept. 1993.
59. Dunford, W.G., Mufford, W., "An Integrated Controller for Current Source Inverter Drive", IEEE ISIE Conference, Budapest, July 1993, pp. 67--72.
60. Ward, P.R.B., Dunford, W.G., "Very Small Solar Powered Pumps for Rural Applications", IAHR Water Systems Symposium, Zimbabwe, July 1993.
61. Le Pocher, H., Dunford, W.G., Laszlo, C.A., "Effect of Distributed Coil Windings on Magnetic Stimulation of Nerve Fibers", IEEE Intermag, Stockholm, Apr. 93, pp. FQ 01.
62. Barnard, J.M. , van Wyk, J.D. and Dunford, W.G., "A New Drive System for Battery Operated Wheelchairs Using a 3 Phase Cage Rotor Induction Machine, IEEE IECON 1992, pp. 138--143.
63. Dunford, W.G., Welder, L. and Ward, P.R.B., "The Production of Impulsive Torques in a Photovoltaic Powered Pumping System", IEEE PESC Conf, Toledo, 1992, pp. 719--725.
64. Nandam, P.K., Cummings, G.F., Dunford, W.G., "Experimental Study of an Observer-based Shaft-Sensorless Variable Speed Drive, IEEE Industrial Appl. Soc. Conf., 1991. pp. 392--396.
65. Dunford, W.G., Liu, G., "Combined Overcurrent and Overtemperature Protection with SENSEFETs, EPE Conf., Florence, 1991, vol. 1, pp. 152--154.
66. Dunford, W.G., Liu, G., "Losses in FET-based Converters With and Without External Flywheel Diodes", EPE Conf., Florence, 1991, vol. 3, pp. 322--325.
67. Nandam, P.K., Cummings, G.F., Dunford, W.G., "Performance and Sensitivity Analysis of an Observer-based Mechanical Sensorless Data Acquisition System", EPE Conf., Florence, 1991, vol. 3, pp. 497--502.
68. Dunford, W.G., van Wyk, J.D., "Harmonic Imbalance in Asynchronous PWM Schemes", IEEE PESC Conf., Boston, 1991, pp. 397--401.*
69. Salazar, A.O., Stephan, R.M., Watanabe, E.H., Dunford, W.G., "Mancais Magneticos Para Motores De Inducao Utilizando Os Enrolamentos Do Estator, 8th Brazilian Conf. on Control, Belem, Sept. 1990, pp. 930--935.
70. Liu, G., Dunford, W.G., "Comparison of Sinusoidal Excitation and Trapezoidal Excitation of A Brushless Permanent Magnet Motor", 4^th IEE Int. Conf. on Power Electronics and Variable Speed Drives, London, pp. 446--450, July 1990.
71. Dunford, W.G., van Wyk, J.D., "The Calculation of Subharmonics in an Asynchronous PWM Induction Motor Drive", IEEE Power Electronics Specialists Conf., San Antonio, June 1990, pp. 672--677.
72. Salazar, A.O., Dunford, W.G., Stephan R., Watanabe, E., "A Magnetic Bearing System Using Capacitive Sensors for Position Measurement", IEEE Intermag, Brighton, May 1990, pp. GC 05.
73. Ward, P.R.B., Cheung, E.A., Dunford, W.G., Ashley, K.J. , "A Directly Driven Photovoltaic Powered Pump for Water Aeration", 1989, SESCI, pp. 83--87.
74. Schultz, J., van Wyk, J.D., Dunford, W.G., Prest, R.B., Landy, C.F., "An Inverter and Induction Motor Traction Drive Applied to Deep Underground Mining Locomotives", 3rd European Conf. on Power Electronics and Applications (EPE), Aachen, Oct. 1989, pp. 1571--1574.
75. Liu, G., Dunford, W.G., "The Investigation into Position-sensorless Operation of a Brushless DC Motor", Proc. First Cdn. Conf. on Electrical and Computer Engg., Vancouver, November 1988, pp. 326--329.
76. Ward, P.R.B., Dunford, W.G., "Photovoltaic Powered Pump Performance from Bright Sunshine Data, 1988, SESCI, pp. 99--104.
77. McAskill, B., Dunford, W.G., "Self-tuning Pole Placement Control of a Manipulation with Flexible Joints", IEEE Pwr. Electronics Specialists Conf., 1988, pp. 445--451.
78. Passmore, W., Dunford, W.G., "The Design of a Maximum Power Point Tracking Circuit for a Photovoltaic Powered Pumping Application", IEEE Industrial Appl. Soc. Conf., 1987, pp. 816--820.
79. Dunford, W.G., Ward, P.R.B., "The Efficient Use of a DC Motor in a Low Voltage Pumping Application", IEEE Industrial Applications Soc. Conf., 1987, pp. 477--480.
80. El Naggar, A.I., Dunford, W.G., "The Design of a Simple Gate Drive Circuit for Low Power GTOs", IEEE Industrial Applications Soc. Conf., 1987, pp. 557--561.
81. Ward, P.R.B., Dunford, W.G., "Photovoltaic Powered Water Pumping B.C. Tel Alternative Energy Conf., 5th October 1987, pp. 75--83.
82. Ward, P.R.B., Dunford, W.G., Brown, L.G., "Field Trials of Photovoltaic-Powered Progressive Cavity Pump", paper 23, American Solar Energy Society Conf., Portland, July 1987, pp. 116--120.
83. Peabody, F., Nyberg, D., Dunford, W.G., "The Use of a Spreadsheet Program to Design Motors on a Personal Computer", 1986, IEEE, Industrial Applications Soc. Conf. Record, pp. 840--845.
84. Peabody, F., Dunford, W.G., Brdicko, J., "An Analysis of a Thin Steel Rotor, Double Sided, Annular, Linear Induction Motor", 1986, IEEE, Intl. Conf. on Linear Induction Machine Application, pp. 840--846.
85. Ward, P.R.B., Dunford, W.G., Ashley, K.I., Proc. Renewable Energy Conf., June 1986, SESCI, University of Manitoba, Winnipeg, "Ice Control in Lakes by Photovoltaic Powered Water Circulation", pp. 41--46.
86. Pulfrey, D.L., Dunford, W.G., Ward, P.R.B., "A Photovoltaic Powered  System for Medium Head Pumping", 1985, 18th IEEE Photovoltaic Specialists Conf., pp. 1637--1642.
87. Ward, P.R.B., Dunford, W.G., Pulfrey, D.L., "Performance of Small Pumps with Solar Power", 1985 Cdn. Soc. of Civil Engineers Conf., pp. 459--477.
88. Dubey, G.K., Dunford, W.G., "Chopper Control of a Compound Motor", 1984 Intl. Assn. of Science & Tech. for Development Power J., pp. 56--60.
89. Ward, P.R.B., Dunford, W.G., "Solar Powered Groundwater Pumping for Medium Heads", 1984, Intl. Hydrological Soc. Publ. No. 144, pp. 249—258 (invited paper).
90. Dewan, S.B., Dunford, W.G., "A Microprocessor Based Controller for a Three Phase Controlled Rectifier Bridge", 1981, IEEE Industrial Applications Soc. Conf. Record, pp. 812--817.
91. Dewan, S.B., Dunford, W.G., "Improved Power Factor Operation of a Three Phase Rectifier through Modified Gating", 1980, IEEE, Industrial Applications Soc. Conf. Record, pp. 830--838.
92. Dunford, W.G., Dewan, S.B., "Design of a Control Circuit for a Two Quadrant Chopper based on the Motorola M6800 Microprocessor, 1979, IEEE, Industrial Applications Soc. Conf. Record, pp. 893--897.
93. Vishloff, L, Dunford, W.G., “A Wireless Communication System for the Control of a Distributed Generation and Storage Electrical System”, PEDAC 04, Irvine, March 2004
94. Dunford, W.G., “The Implementation of DC Utilization in Distributed Generation Systems “, PEDAC 04, Irvine, March 2004

95.   Buchholtz V, Neilson J, Wang M, Casson D, Dunford W, “DC Distribution Systems for Commercial Buildings”, BC Hydro Strategic R&D Study Project 6639-23-00, May 1995.

96.   Besant, C., Pullen, K., Etemad, M., Fenocchi, A., Ristic, M., Baines, N., Dunford, W., . "Hybrid Traction --- A Solution for A Not Too Distant Future", Yearbook Autotechnical Trends, 1993, pp. 3.3.1 --- 3.3.13. HTS  Autotechniek, Hogeschool Gelderland, Apeldoorn, Netherlands.

97.   Laszlo, C.A., Dunford, W.G., Hershler, C., "Development of a Magnetic Stimulator", HDF Grant 28--29, Final Rpt., October 1990.

98.   Ward, P.R.B., Pulfrey, D.L., Dunford, W.G., "Photovoltaic Powered Systems for Medium Head Pumping", NRC Project 01S.31926--3--3030, Final Rpt., January 1985.