Steady-State Analysis and Design Considerations of High Voltage Gain Switched Z-Source Inverter with Continuous Input Current
Abstract
In this paper, a new topology for Z-source inverter based on switched Z-source network is proposed. The proposed switched Z-source inverter can provide high voltage gain in low duty cycles. The continuous input current is one of the other advantages of the proposed inverter. The performance of the proposed inverter is investigated in different operating modes and the voltage and current equations of all elements and equations of critical inductance are calculated. Furthermore, a new control method is proposed for the presented inverter. In addition, the power losses and efficiency analyses are presented. The comprehensive comparison between the proposed inverter and the other conventional Z-source inverters shows its excellent performance. Finally, to prove the correct operation of the proposed topology, the experimental and simulation results using PSCAD/EMTDC software are presented.
EXISTING SYSTEM:
Moreover, the voltage stresses on capacitors are less than the conventional ZSI but their boost factor is equal to the boost factor of ZSI. In, by using coupled inductors, a topology has been presented for QZSI that can decrease the input current ripple. Unlike the conventional ZSI, bidirectional switches have been used. To achieve the low input current ripple and appropriate coupling, the value of inductors should be designed appropriately. However, the design of coupled inductors has some practical problems. Another generation of the ZSIs has been presented , that is called switched boost inverter (SBI). This inverter has low number of passive elements in comparison with the conventional ZSI but the boost factor of SBI is less than that of the conventional ZSI and its input current is discontinuous. To improve the boost factor of SBI, another structure has been presented in that increases the boost factor of the SBI but its input current is still discontinuous. In, the half bridge SBI has been presented which uses two switched boost network and has higher boost factor than SBI, but the input current of it is still discontinuous. In, different types of switched ZSIs have been presented that their boost factors are equal to the boost factor of the conventional ZSI and they have continuous input current. In some other papers, developed structures have been presented to obtain high voltage gain. L-Z-source inverter (LZSI) has been presented. There are not any capacitors in the Z-source network of LZSI and only switched inductors cells are used to increase gain. This structure solves the inrush current problem in the ZSI but with only one cell, its boost factor is very low. The extended QZSI has been presented. Increasing output voltage and lack of inrush current are its advantages. In, by using several impedance networks, the boost factor of the presented topology has been increased. However, volume, weight, cost, and the power losses of the inverter are increased.
PROPOSED SYSTEM:
In this paper, a new topology for switched ZSIs is proposed. The proposed topology improves the voltage gain of conventional topologies such as SBI and ZSI. It also has continuous input current that makes it be suitable for power generation from renewable energy. The analysis of the proposed inverter in different operating modes is given and the voltage and current equations of all elements are calculated. Regarding the fact that by changing the value of inductors, the operation of inverter can be changed, the relation of critical inductance is extracted. Moreover, a suitable PWM control for the proposed topology is presented. A comprehensive comparison between the proposed topology and the other ZSIs is presented. Finally, in order to reconfirm the validity of given theories, the experimental and simulation results by using PSCAD/EMTDC software are provided.
CONCLUSION
In this paper, a new topology was proposed for ZSIs based on switched impedance network. The complete analysis of the proposed topology was presented under different operating conditions. It was determined that despite the same number of passive elements with conventional topologies, the proposed D the boost factor of the proposed topology is 2.1 times greater topology has a higher boost factor. For example, in 0.3 than the boost factor of the conventional ZSI. It was determined by changing the value of the modulation index, the variations of voltage and current elements were identified. By increasing the amount of modulation index to its maximum value, the following results were obtained: The output voltage will not be zero during nST mode. The value of the critical inductance is decreased. The current stresses of inductors are increased but the current ripple of inductors will not be changed. The capacitors’ voltages ripples are increased partially but the average amount of capacitors’ voltage will not be changed. f and M , if the values of inductors are selected greater than the critical inductances, According to the values of V , i D , ST s the inverter operates in suitable modes. The optimal values of elements were designed for the proposed topology. Finally, the accuracy of given theories were verified by experimental and simulation results using PSCAD/EMTDC software.
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