Quasi Cascaded H-Bridge Five-Level Boost Inverter

ABSTRACT

Latterly, multilevel inverters have become more attractive for researchers due to low total harmonic distortion (THD) in the output voltage and low electromagnetic interference (EMI). This paper proposes a novel single-stage quasi-cascaded H-bridge five-level boost inverter (qCHB-FLBI). The proposed five-level inverter has the advantages over the cascaded H-bridge quasi-Z-source inverter (CHB-qZSI) in cutting down passive components. Consequently, size, cost, and weight of the proposed inverter are reduced. Additionally, the proposed qCHB-FLBI can work in the shoot-though state. A capacitor with low voltage rating is added to the proposed topology to remove an offset voltage of the output AC voltage when the input voltages of two modules are unbalanced. Besides, a simple PID controller is used to control the capacitor voltage of each module. This paper presents circuit analysis, the operating principles, and simulation results of the proposed qCHB-FLBI. A 1.2-Kva laboratory prototype was constructed based on a DSP TMS320F28335 to validate the operating principle of the proposed inverter.

INDEX TERMS

Cascaded H-bridge inverter, five-level inverter, quasi-Z-source inverter, boost inverter, shoot-through state

CONVENTIONAL DIAGRAM:

Fig. 1. Conventional CHB five-level inverters based on (a) DC-DC boost converter

EXPECTED SIMULATION RESULTS:

 

Fig. 2. Simulation results when Vdc1 = Vdc2 = 50 V. From top to bottom: (a) five-level output voltage, load and inductor currents, VC1, VC2, Vdc1 and Vdc2, (b) inductor currents, capacitor voltages, DC-link and diode Da1 voltages of module 1, DC-link and diode Da2 voltages of module 2, (c) harmonic spectrum of five-level output voltage, and (d) harmonic spectrum of load current

Fig. 3. Simulation results when Vdc1 = 50 V and Vdc2 = 60 V. From top to bottom: (a) five-level output voltage, load and inductor currents, VC1, VC2, Vdc1, Vdc2 and VCd, (b) five-level output voltage, inductor currents, capacitor voltages, DC-link and diode Da1 voltages of module 1, DC-link and diode Da2 voltages of module 2, (c) harmonic spectrum of five-level output voltage, and (d) harmonic spectrum of load current.

CONCLUSION

A New Single-Phase Single-Stage CHB Five-Level Inverter With Boost Voltage Ability Has Been Proposed In This Paper. The Proposed Inverter Has The Following Main Features As: Five-Level Output Voltage, Reduction In Number Of Passive Components And Shoot-Through Immunity. With The Simple PID Controller, A Constant Capacitor Voltage Can Be Achieved With An Excellent Transient Performance Which Enhances The Rejection Of Disturbance, Including The Input Voltage And Load Current Variations. Also, Circuit Analysis And PWM Control Strategy For The Proposed System Are Shown. Simulation And Experimental Results Are Shown To Verify The Validity Of The Proposed Qchb-FLBI.

REFERENCES

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