Control of the Z-Source Inverter for FCHEV with the Battery Connected to the Motor Neutral Point

The Z-source inverter provides a simple single stage solution for fuel cell-battery hybrid electric vehicles (FCHEV). It utilizes an exclusive Z-source (LC) network to link the main inverter circuit to the fuel cell (or any dc power source). This paper presents the control of the Z-source inverter for FCHEV with the battery connected to the motor neutral point. By controlling the shoot-through duty cycle and modulation index, the inverter can produce any desired output ac voltage. By controlling the shift of the reference signal of the PWM signal, the undesirable operation modes of the Z-source inverter can be eliminated and the state of charge (SOC) of the battery can be controlled. Therefore there is no need for a separate dc/dc converter. These facts make the Z- source inverter highly desirable for use in hybrid electric vehicles, as the cost and complexity is greatly reduced when compared to traditional inverters. This concept and the control method will be demonstrated by simulation results.