Transformerless Micro-Photovoltaic Inverter Design
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Solution Overview
Problem
Existing micro-photovoltaic inverters are inefficient and costly due to their reliance on transformer-type DC/DC converters, which require large installation spaces and expensive components, and struggle to achieve high voltage transformation ratios effectively.
Innovation Solution
A transformerless micro-photovoltaic inverter design utilizing an interleaved clocking mode between inverting and non-inverting DC-DC converters, which doubles the switching frequency, reduces the need for expensive transformers, and employs a divided DC link with capacitors to isolate output voltage levels, enabling a compact and cost-effective solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a transformer-type DC/DC converter is used to achieve high voltage transformation ratio, then the voltage transformation capability is improved, but the device complexity, cost, and installation space increase
Solution Approach 1:
The patent extracts and removes the transformer component from the DC/DC converter, transitioning from a transformer-type topology to a transformerless topology. This eliminates the need for expensive transformer components while achieving the required voltage transformation through alternative circuit configurations involving switches, diodes, and capacitors.
Solution Approach 2:
The patent changes the operating parameters by using high-frequency switching (doubled switching frequency through interleaved operation) to achieve voltage transformation without a transformer. The circuit operates in discontinuous conduction mode with specific duty cycles to achieve the desired voltage multiplication effect.
2Power
If a transformer-type DC/DC converter is used, then voltage transformation is achieved, but the installation space and manufacturing cost increase
Solution Approach 1:
The transformer component, which occupies significant installation space, is completely removed from the system. The voltage transformation function is replaced by a transformerless circuit topology using active switches and passive components that occupy substantially less space.
Solution Approach 2:
The patent replaces expensive transformer components with cheaper solid-state switching components and passive elements. The transformerless topology uses standard electronic components that are less costly and more compact than traditional transformer-based solutions.
3Power
If a transformer-type DC/DC converter is used, then voltage transformation is achieved, but the efficiency decreases
Solution Approach 1:
The patent replaces the electromagnetic transformation mechanism (transformer) with a solid-state electronic switching mechanism. This substitution eliminates core losses, copper losses, and other inefficiencies associated with transformers, achieving higher conversion efficiency through MOSFET/IGBT switching and diode rectification.
4Area of stationary object
If the switching frequency is increased to reduce filter size, then the filter components become smaller and cheaper, but the electromagnetic interference increases
Solution Approach 1:
The patent employs interleaved periodic switching of two parallel DC/DC converter circuits operating at different phases. This periodic alternating operation smooths the input current ripple and reduces electromagnetic interference while maintaining high switching frequency benefits for compact filter design.
Solution Approach 2:
The patent merges two parallel DC/DC converter circuits operating in interleaved fashion. The combined operation of both converters with phase-shifted switching reduces the amplitude of current ripple and electromagnetic interference compared to a single converter operating at the same switching frequency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The transformerless design enhances efficiency, reduces costs, and minimizes physical size while maintaining high voltage transformation capabilities, allowing for efficient conversion of DC to AC voltage for grid feeding.
Implementation Method 1
A first stage of a micro-photovoltaic inverter is formed with a DC/DC converter, which is configured as a transformer-type transducer in a manner known per se
Implementation Method 2
This stage generates an AC voltage from the high DC voltage provided by the DC/DC converter by appropriate pulse-width modulation (PWM)
Implementation Method 3
a photovoltaic module that provides a DC voltage (DC) of approximately 20V-50V during operation
Data Source
AI summary
An inverter that is a micro-photovoltaic inverter includes a DC-DC converter on an input side of the inverter. The DC-DC converter has three output voltage levels. The inverter also includes an inverter element having at least three input voltage levels. The inverter element is electrically connected to the DC-DC converter.