Development of a Holistic Solution for VVVF Drives

摘要

The use of VVVF drives is the industrial norm of the modern elevator industry, irrespective of whether a conventional three-phase induction motor or the PMSM motor is employed. Several concerns of such VVVF drives have to be looked into. First, most drives are still using braking resistors during the braking process though re-generative braking devices are getting more popular, thus not energy efficient. Second, the power quality of most drives is unsatisfactory due to the uncontrolled rectifier at the first stage of the system, calling for the installation of either an active or passive filter. Third, these drives usually cannot tolerate voltage dips during adverse weather conditions or transients of the power transmission system. Fourth, a separate meter has to be installed to monitor all parameters related to the power quality. An ITF (Innovation Technology Fund) funded project was conducted in Hong Kong Polytechnic University to develop a holistic device to tackle all these issues. The paper reports the design and prototype development.