1. School of AutomationGuangdong University of TechnologyGuangzhou510006People's Republic of China
2. Power Electronics, Machines and Control Research GroupUniversity of NottinghamNottinghamNG7 2RDUK
3. SEW‐EURODRIVE GmbH & Co KG76646BruchsalGermany
4. School of Electronic and Information EngineeringSouth China University of TechnologyGuangzhou510640People's Republic of China