Controller Design of Power Quality-Improving Appliances

1. Controller Designof Power Quality-Improving Appliances D. J. Hammerstrom, N. Zhou, and N. Lu Pacific Northwest National Laboratory 902 Battelle Blvd., P. O. Box 999 Richland, WA 99352 USA Donald.Hammerstrom@pnl.gov (509) 372-4087 PNNL-SA-55816

2. Excessive PQI current correction Perfect PQI current correction current Inadequate PQI current correction Non-PQI currents time Power Quality-Improving Appliances Let one load improve the power quality and power factor for an entire premise

3. Premise current before PQI PQI appliances are like filters, but they can only consume energy. Where the energy can be put to good use, the PQI is, in theory, 100% efficient. IPremise V IPremise PQI current Sum of premise and PQI currents IPremise+PQI 3

4. Measure and Improve Current at Premise Service Panel

5. Controller Input Signals Note: PQI controller design can be greatly simplified by using an inexpensive power factor control chip. • Gain • Rectified ac voltage • Rectified premise current

6. A Simple, Nearly Failsafe Power Circuit Most circuit failure modes would result in normal, rated appliance conduction.

7. Floating Driver Circuits • Optically coupled PWM signal • Adjustable positive and negative drive bias • Same circuit works for both power switches • Same PWM signal sent to both switches

8. Prototype Hardware Test Stand and Load Driver and Power Circuits

9. Same Premise IRMS; PQI Load is Active Only When Needed PQI Appliance Active PQI Appliance Inactive

10. Effect of PQI Gain Input Too High Active Too Low

11. Effect of PQI Load Impedance High Z; Low PQI Load Low Z; High PQI Load

12. Conclusions PQI appliances are an undiscovered opportunity Simple effective circuit designs Comparable to, but less expensive than, filters Improve premise power quality and power factor while performing useful tasks like heating water Theoretically high effective efficiency