variable frequency speed regulation 变频调速

variable frequency speed control 变频调速

variable frequency speed control system 变频调速系统

variable frequency regulating speed 变频调速

variable speed constant frequency generator 定频变速发电机 ; 变速恒频发电

variable frequency speed-regulating 变频调速

variable-speed constant-frequency 变速恒频

variable frequency and speed regulation 变频调速