EMI Filter Design for a Three-Phase Buck-Boost Y-Inverter VSD With Unshielded Motor Cables Considering IEC 61800-3 Conducted and Radiated Emission Limits

• Published in: IEEE transactions on power electronics Vol. 36; no. 11; pp. 12919 - 12937
• Main Authors: Menzi, David, Bortis, Dominik, Kolar, Johann
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Cable shielding; Cables; Circuit design; Converters; D C motors; DC motors; DC-side/ac-side electromagnetic interference (EMI) filter design; electromagnetic compatibility; Electromagnetic interference; Emissions control; Equivalent circuits; Filter design (mathematics); IEC 61800-3; IEC Standards; Insulated gate bipolar transistors; Inverters; Measurement techniques; Modular structures; MOSFETs; Residential areas; Semiconductor devices; Switches; Switching; three-phase buck–boost inverter; Variable speed drives; variable speed drives (VSDs); Y-inverter
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2021.3075785

The standard converter concept employed in variable speed motor drives is the two-level three-phase Si insulated-gate bipolar transistor voltage source inverter with its switch nodes connected to the motor terminals via shielded cables to avoid excessive high-frequency noise emissions. However, high <inline-formula><tex-math notation="LaTeX">dv/dt</tex-math></inline-formula> pulses of the inverter pose substantial stresses on the motor, which are further intensified by the ever-faster switching speeds of wide band-gap semiconductors, hence promoting interest in inverters with full-sinewave output filters, which potentially enable the use of inexpensive unshielded motor cables. However, the IEC 61800-3 standard dictates stringent conducted and radiated emission limits on unscreened power interfaces. In this article, a dc input and ac output filter structure allowing operation with unshielded cables is derived for a phase-modular 11-kW buck-boost Y-inverter motor drive system employing 1.2-kV SiC MOSFETs with a switching frequency of 100 kHz. First, regulations and measurement techniques for conducted and radiated emissions of motor drives are analyzed. Next, the operating principle of the Y-inverter is described and an electromagnetic interference equivalent circuit is derived, followed by a systematic filter design. Finally, measurements are conducted on an ultracompact hardware prototype of the converter system with 12 kW/dm 3 (197 W/in 3 ) power density, where the results indicate full compliance with the IEC 61800-3 conducted and radiated emission limits for operation with unshielded dc supply and motor cables in a residential area.