Filter networks for long cable drives and their influence on motor voltage distribution and common-mode currents

Abstract

Filter networks for long cable drives have been studied in the last decade to solve the over-voltage problem at the motor terminals. However, little research has been dedicated to analyze their influence on the voltage distribution in the motor stator winding and on the circulation of the common-mode currents. In this paper, the project of dvldt filters through simulation and analysis from previous works is extended including the motor voltage distribution and commonmode current analysis. Simulation and experimental results are presented demonstrating the usefulness of the filter networks on the motor over-voltage mitigation. Three filter topologies will he discussed and compared here: RLC Filter at the motor terminals, RLC Filter at the inverter output and Reactor Filter, which is extensively used in the industry. Simulation and experimental results demonstrates that the RLC Filter at the inverter output is the most interesting solution among the main types of passive filter networks. KEYWORDS Industrial Drives; Electrical Drive Systems Design and Applications; Over-voltage and dvldt Filter Design. ~:.INTRODUCTIONThe main goal of this paper is to demonstrate that the RLC Filter at the inverter output is the most interesting passive solution to mitigate the' existent over-voltage problem in the actual adjustable speeddrives [l], [21, [31, [41,[5]. The passive dv/dt filters have k e n fully exploited in previous works [6], [7], in which a convenient simulation tool has been suggested to design filter networks through simulation and analysis. In this paper, other figures of merit are added to this design process: the voltage distribution in the machine stator winding and the common-mode current circulation.The filter network compkisons also include the 5% reactor filter, a standard dv/dt filter output in industry. The dv/dt filter topologies are designed for a 3 hp induction motor drive system with 250 meters of power cable length. Selected simulation and experimental results are presented showing the usefulness of the filters. It will be shown that the RLC Filter placed at the inverter output presents the best agreement among the conflicting goals: minimal over-voltage, minimal filter losses, minimal common-mode currents and better voltage distribution in the machine stator winding, FILTER DESIGN THROUGH SIMULATIONA N D ANALYSIS It's known that the main philosophies utilized to solve the over-voltage problem are: to match the load to the cable Thomas A. Lip0 Gin Venkataramanan UW-Madison ECE Department 1415 Engineering Dr. Madison, WI, 53706 -USA characteristic impedance and to increase the voltage pulse rise time [7], [SI, [91. The networks placed at the motor terminals follow the first philosophy. On the other hand, the networks placed at the inverter output follow the second one. In this last case, although the reflection phenomena exists the overvoltage does not appear because the voltage pulse rise time is somehow kept bigger than the voltage pulse traveling time.The design process through simulation and anal...

Overvoltage at motor terminals in SiC-based PWM drives

“…Several works [6,10,24,26,29] highlight the harmful impact of repeated transient overvoltage on the EIS of motor fed by fast inverter. Passive [16,17,19,25] and active [21,40] filters at the inverter output or at the motor input have been proposed to mitigate overvoltage at motor terminals.…”

Threshold for Induction Motor Terminal Transient Peak Voltage with Fast Switching Inverters

“…This in turn may lead to transients with high voltages on the electric motor, especially in applications with long supply cables [3]. Various proposals of how to model the switching behavior with long-cable-fed motors have been made in literature [3,4,5,6]. Repetitive high voltage pulses will decrease the lifetime of the insulation [7].…”

“…Repetitive high voltage pulses will decrease the lifetime of the insulation [7]. To reduce the peak voltage experienced by the insulation of the motor windings, filter solutions have been proposed [4,5,8]. The purpose of the filter is both to reduce the peak voltage during the transient and to increase the rise time of the voltage waveform at the motor to decrease the turn-to-turn voltage in the motor windings.…”

A Controlling Method of Motor-Terminal Surge Voltage and Induced-Electromagnetic Interference Noise for Electric Vehicles

“…Here we focus on the surge voltage appearing at motor terminals and on induced-EMI noise because they cause various problems like deterioration of motor insulation and degradation of torque control performance, etc., which shorten the vehicle lifetime and decrease the vehicle reliability. The surge voltage occurring when using long leads (for example, more than 15 m, the choice of which depends on the switching speed of the power devices used) for connections between the PWM inverters and the motor terminals has been investigated [8]- [12] and countermeasures have also been studied [13]. However, the surge voltage appearing at motor terminals, when connected to a PWM inverter with short leads, (for instance less than 5 m), which are applicable to EVs, has received little attention.…”