Adaptive Control of Surge Impedance for Electric Motors in Motor Drive Systems

TL;DR

This paper proposes an adaptive electronic circuit to control surge impedance in electric motor drives, reducing reflected wave effects and improving motor insulation longevity.

Contribution

It introduces a high-bandwidth circuit that dynamically matches surge impedance, offering an alternative to traditional filtering methods in motor drive systems.

Findings

Effective suppression of high-frequency voltage ringing around 1 MHz.

Significant reduction in leakage currents and overvoltage stress.

Rapid impedance adjustment improves motor insulation reliability.

Abstract

This article studies the possibility of controlling the surge impedance of the electric motor in motor drives. The existing solution to suppress (or eliminate) the reflected wave impact on the motor insulation run by a Si-IGBT or SiC-MOSFET-based drive is to use either a sinewave filter or dv/dt filter. The alternative solution suggested in this article is to implement a high-bandwidth electronic circuit at the end of the cable or at the motor terminals to match the surge impedance of the cable and motor. The high-frequency voltage ringing due to the reflected waves in motor drives is around 1 MHz, depending on the cable parameters and the length of the cable. In the proposed method, the electronic circuit can quickly detect the dv/dt rise and fall edges and adjust the electronic circuit equivalent impedance when pulses arrive the motor terminals. Thus, the cable and motor surge impedances can be matched over a short time to prevent reflected waves. As a result, the leakage currents passing through the ball bearing and overvoltage stress on the motor insulation can be suppressed significantly.