The six-step mode: Unwanted or rather the ideal voltage modulation method

Autoren

M. Eng. Thomas Zeltwanger, Dr.-Ing. Helge Sprenger, Dipl.-Ing. Mark Damson, Dipl.-Ing. Manabendra N. Gupta, Robert Bosch GmbH

Jahr

2019

Zusammenfassung

In today’s electric and (plug-in) hybrid vehicles, properties such as the overall driving efficiency are an essential design goal next to its pure drivability characteristics. Component costs and power rating are additional factors to determine the commercial success of the product. Different voltage modulation methods and their configuration may be considered in design decisions to further optimize the electric drive train system.
Currently, the classic SVPWM (Space Vector Pulse Width Modulation) is used as the standard voltage modulation method. Other modulation methods are hardly applied to the powertrain of electric vehicles. Reasons for that could be: No sufficient practical experience, retention in terms of doubts concerning unknown or disadvantageous system interactions such as NVH (Noise-Vibration-Harshness) or restricted controllability.
As a representative for the possibilities of different other voltage modulation, the “classic” six-step mode (SSM or ger. Blockbetrieb), also known as fundamental frequency clocking, with its significant system advantages at high machine speeds will be introduced and discussed. Measurements and simulations cannot confirm supposed disadvantages. In addition, it was possible to implement a series-ready solution on an electronic control unit (ECU) with the help of the synchronous switching method (ger. Synchrone Taktung or Synchrone Steuerverfahren) to solve classic controllability problems of the six-step mode. Only the voltage modulation method was enhanced, the fieldorientated current control is the same as for SVPWM.

Mitglieder-Login