Bearing Currents and Their Relationship to PWM （轴承电流PWM和他们的关系）.pdfVIP

IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 12, NO. 2, MARCH 1997 243 Bearing Currents and Their Relationship to PWM Drives Doyle Busse, Jay Erdman, Member, IEEE, Russel J. Kerkman, Senior Member, IEEE, Dave Schlegel, Member, IEEE, and Gary Skibinski, Member, IEEE Abstract— This paper examines ac motor shaft voltages and operating on VFD include electric field breakdown of the the resulting bearing currents when operated under pulse width oil film resulting in EDM currents and lower level modulation (PWM) voltage source inverters. The paper reviews or electrostatically induced currents altering the chemical the mechanical and electrical characteristics of the bearings and motor in relation to shaft voltages and bearing currents. A composition of the lubricant. brief review of previous work is addressed, including the system Recently, the authors presented their findings on EDM and model and experimental results. The theory of electric discharge its relationship to PWM inverter operation [4]. In contrast to machining (EDM) is presented, including component calculations traditional magnetic imbalance effects found in sine wave- of the system elements. The effect of system elements on shaft driven machines, it was shown that PWM inverters serve voltages and bearing currents are evaluated experimentally and the results compared to theory. A design calculation is proposed to excite a capacitive coupling between the stator and rotor. that provides the relative potential for EDM. Finally, the paper This couplin