NC HVVF series medium voltage AC Drive is a voltage source inverter based on IGBT and cell series multilevel PWM technology. Nancal HVVF adopts vector control and combines PWM technology to realize variable frequency speed control of medium voltage motor. It is used to satisfy the process automation, reducing energy consumption and protecting environment. NC HVVF can achieve output voltage up to 18kV with perfect sinusoidal wave form by multilevel PWM. It also can directly drive almost all kind of medium voltage motors without step up transformer.