Wuma gear reduction motor also has become popular.

While all Wuma gear reduction motor control the speed of an AC induction motor by varying the motor's supplied voltage and frequency of power, they all do not use the same designs in doing so. There are three major helical gear motor designs commonly used today: pulse width modulation (PWM), current source inverter (CSI), and voltage source inverter (VSI). Recently, the flux vector drive also has become popular.