Description
High-frequency current injection into each of the switch-nodes, thereby making zero-voltage-switching operation of the devices possible. The topology achieves this functionality while using the same number of devices as conventional two-stage and single-stage high-frequency-link or DAB-based solutions. Further, following a control-oriented power pulsation decoupling strategy involving dynamic variation of phase-shift, twice line frequency energy buffering can be handled on the high-voltage secondary side, thereby resulting in reduction in decoupling capacitance requirement. Working principle of then circuit and the associated control scheme is described followed by detailed ZVS analysis. Simulation studies and experimental tests on a 310 W prototype verify circuit operation and exhibit efficiency improvements compared to a similar two-stage solution.
Introduction
This paper proposes a novel dual-active bridge (DAB)-based high-frequency-isolated DC-AC converter topology suitable for PV micro inverter applications. The circuit configuration on the secondary sides of the employed three-winding transformer results in high-frequency current injection into each of the switch-nodes, thereby making zero-voltage-switching (ZVS) operation of the devices possible. High-frequency transformer-isolated single-phase inverter topologies employed in applications like photovoltaic(PV) and fuel-cell inverters can be broadly classified as single-stage or multi-stage. Power electronics?is a key technology for energy saving and high functionalizing in energy usage. The power electronics application has a tendency toward high voltage and lessening current to reduce conduction loss. The key component for high voltage power electronics is a power semiconductor device for the switching operation. Diamond is a prospective semiconductor material for a power device. It is expected to be available both as an active control transistor and subsidiary operated diode as a power device. But only the diode is available as a diamond power device at the current time.
Existing system
High-frequency ac-link-based architectures represent another category of single-stage isolated topologies and can be further classified into two types. In the first type [4], [5], a high-frequency square wave or quasi-square wave generated by a primary-side inverter is appropriately modulated by a secondary-side cycloconverter with the objective of rendering a line-frequency sinusoidal profile to the current of an output inductive filter. The major advantages of this approach are its non-reactive power processing and zero-voltage-switching (ZVS) operation of the devices. But a critical concern with this topology is the voltage spike appearing across the secondary side devices, which necessitates the use of auxiliary voltage clamping circuits.
Disadvantage of the system
A critical concern with this topology is the voltage spike appearing across the secondary side devices, which necessitates the use of auxiliary voltage clamping circuits.
Proposed system
The key advantage of the proposed solution is its ability to realize ZVS turn-on of all switches across the ac line cycle, unlike conventional two-stage solutions, which miss ZVS over half the ac line cycle. The topology achieves this functionality without using additional circuitry, as is required with ZVT-based solutions. Though the proposed circuit introduces additional conduction losses compared to two-stage topologies, ZVS operation can lead to better efficiency in cases where switching losses are significant, as is experimentally demonstrated. Further, by employing a control strategy involving dynamic variation of phase-shift over an ac line cycle, low-frequency power decoupling can be handled by the high voltage secondary dc bus capacitor. This results in substantial reduction in decoupling capacitance requirement, allowing a film-capacitor-based implementation, which is not possible in standard single-stage topologies.
Advantages of the proposed system
- The circuit configuration on the secondary sides of the employed three-winding transformer results in high-frequency current injection into each of the switch-nodes, thereby making zero-voltage-switching (ZVS) operation of the devices possible.
- The topology achieves this functionality while using the same number of devices as conventional two-stage and single-stage high-frequency-link or DAB-based solutions. Further, following a control-oriented power pulsation decoupling strategy involving dynamic variation of phase-shift, twice line frequency energy buffering can be handled on the high-voltage secondary side, thereby resulting in reduction in decoupling capacitance requirement.
Block diagram
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Circuit diagram
Block diagram explanation
- Input
Concept of this project mainly focus on renewable energy sources like solar energy, fuel cell source etc.
- Main circuit
Zero voltage switching, low decoupling capacitance is the aimed areas of this project, with the particular structure of circuit which is being achieved.
- Controller
Brain of the circuit, which will control all the functions of the circuit, all the modes of this circuit perfectly achieved by the controller
- Feedback
For having a stabilized output closed loop data has selected which will transfer the instant values of output data to the controller.
- Output
Delivering energy ports from the output of the circuit being used.
Hardware requirement
- Arduino microcontroller
- Circuit components
Vac = 110 V rms
Pav(max) = 310 W
Vpv = 25-35 V
Lpv = 140 uH
Cpv = 20 uF
Lin = 20 uF
Cin = 40 Uh
Cb = 40 _F
Turns-ratio = 1:2.13:2.13
Llkp = 60 uH
fs = 25 kHz
Cdcp = 40 uF
Lf = 3.5 mH
Cf = 2.2 uF
Mosfet switches (irf250, irf840)
- Input supply
- Output measurement device
Software required
- Arduino ide
- Matlab (simulink)
Reference
- B. Kjaer, J. K. Pedersen, and F. Blaabjerg, ?A review of single-phase grid-connected inverters for photovoltaic modules,? IEEE Trans. Ind. Appl., vol. 41, no. 5, pp. 1292?1306, Sep./Oct. 2005.
- H. Wills, F. E. Hall, S. J. Strong, and J. H. Wohlgemuth, ?The AC photovoltaic module,? in Proc. 25th IEEE Photovolt. Spec. Conf., 1996, pp. 1231?1234.
T. Kerekes, R. Teodorescu, and U. Borup, ?Transformerless photovoltaic inverters connected to the grid,? in Proc. 22nd Annu. IEEE Appl. Power Electron. Conf. (APEC), 2007
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