A 240° Phase Voltage Clamped Inverter for Electric Drives

A 240° phase voltage clamped inverter is proposed for electric drives to extend motor speed and power ranges even at low traction battery voltage, reduce inverter power loss, eliminate the challenge of dc bus voltage tracking a desired <inline-formula> <tex-math notation="LaTeX">$6{f}$ </tex-math></inline-formula>-frequency voltage waveform even if the motor speed is high (e.g., motor <inline-formula> <tex-math notation="LaTeX">${f} > $ </tex-math></inline-formula> 1000 Hz), and eliminate power inductors and HF transformers and use less additional power devices while achieving voltage boost. The 240° phase voltage clamped control is proposed for the case of motor phase voltage amplitude higher than Vb/<inline-formula> <tex-math notation="LaTeX">$\sqrt {3}$ </tex-math></inline-formula> (Vb is the battery voltage); if there is no voltage boost needed, the inverter operates in SVPWM or six step mode. The proposed inverter has no switching for two-thirds of switches, so power loss has a significant reduction. The inverter output voltage has a low CMV. Simulation results verify the proposed 240° phase voltage clamped inverter and control method. The inverter performance evaluation shows higher efficiency of the proposed inverter compared with the traditional 2-level inverter.