Control And Design For Z-Source Converter Based On DSP

The traditional converter includes voltage source converter and current source converter, It is widely used in all kinds of conversion by way of making the power transform between DC/AC and AC/DC. However, both of the converters have barriers and limitations: they are either a boost or a buck converter, can not satisfy boost/buck the voltage at the same time just depend on single stage power conversion, So the output voltage range of the converter system is always limited, Either higher or lower the input voltage, That makes the application come under limited. In order to get a lower voltage or higher voltage relative to input voltage, an additional DC-DC converter to buck the output voltage or to boost the output voltage is needed, which reduces the efficiency of the system, and in a traditional converter, the upper and lower devices of each phase leg could be gated ON (or OFF) simultaneously by EMI noise, which would destroy the device by overrun current or voltage directly, and decrease reliability of the system. To avoid the state, the method of increase dead time has been applied. It would result in the distortion of the voltage and current waveform.In order to overcome the problems of the traditional converter, a novel converter named as Z-source converter is presented, which gets some unique and predominant capability by employing a Z type impedance network (Z-network) to the traditional converter, it makes the shoot-through state possible, which avoids the possibility of ruining by EMI noises. And the shoot-through state allows the Z-source converter to Buck and Boost its output voltage.According to the different structure of topology and different demand of application, The Z-source converter is consist of Z-source inverter and Z-source rectifier. Based on the analysis of the operating principle about how to buck/boost voltage, the state-space-average maths model and small-signal-disturbance maths model are presented in this thesis. several commonly used PWM modulation strategy of the novel Z-source converter are compared and analyzed in detail. Based on the aboved theory analysis, a prototype platform of the 2kw three-phase Z-source inverter is built for grid-connected pv system. But because of the reverse blocking characteristic of the diode, the Z-source inverter can not realize dual energy flow. Based on this, another prototype platform of the 2kw three-phase Z-source rectifier is built for battery charge-discharge system. the simulation and experimental results of the two typical applications have been performed to confirm the analysis. They are quite consistent with the theoretical analysis. Validated new characteristics of the Z-source converter.