Transformerless Bi-directional Voltage Converter
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Solution Overview
Problem
Current grid-tied energy storage systems face inefficiencies due to the use of transformers for voltage conversion, which result in energy loss, complexity, and limitations in bi-directional conversion capabilities, particularly in transformerless approaches.
Innovation Solution
A bi-directional, transformerless voltage conversion system utilizing a multi-stage electric voltage converter with switches and capacitors, allowing for direct conversion between low and high voltages without the need for isolated DC sources, leveraging a modified switched multiplier topology inspired by the Marx generator for efficient and instantaneous voltage conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a transformer is used for voltage conversion in grid-tied energy storage systems, then voltage conversion is achieved, but energy loss increases and system complexity increases
Solution Approach 1:
The patent removes the transformer component from the voltage conversion system, extracting the source of energy loss and complexity. The transformerless voltage conversion is achieved through a multi-stage converter with capacitors and switches that directly convert voltages without electromagnetic transformation, eliminating transformer-related losses and simplifying the system architecture.
Solution Approach 2:
The patent replaces the electromagnetic mechanism of transformer-based voltage conversion with an electronic switching mechanism. The multi-stage converter uses controlled switching of capacitors and power electronic devices to achieve voltage conversion, substituting the mechanical/electromagnetic transformer system with a more efficient electronic system that reduces energy loss and complexity.
2Adaptability or versatility
If a transformerless voltage conversion approach is used, then energy loss is reduced and complexity is decreased, but bi-directional conversion capability is limited
Solution Approach 1:
The patent implements dynamic switching control in the multi-stage voltage converter, where the switching states of capacitors and power electronic devices are dynamically adjusted based on the desired conversion direction. This dynamic control enables the system to operate bidirectionally (voltage boosting and bucking) while maintaining efficiency, as the switching mechanism can be reconfigured instantaneously without the limitations of transformer-based systems.
Solution Approach 2:
The multi-stage voltage converter is designed with universal functionality to perform both voltage boosting and bucking operations. The same capacitor and switching network that reduces energy loss in unidirectional conversion is configured through control logic to enable bidirectional operation, making the system versatile for grid-tied energy storage applications requiring both charging and discharging modes.
3Speed
If traditional voltage conversion methods are used, then system stability is maintained, but conversion speed is slow and instantaneous response is not achieved
Solution Approach 1:
The patent employs periodic switching action in the multi-stage voltage converter, where capacitors are charged and discharged in controlled periodic cycles through power electronic switches. This periodic switching enables instantaneous voltage conversion response, as the switching frequency can be modulated to achieve rapid voltage changes while maintaining system stability through controlled duty cycles and synchronization with the grid.
Solution Approach 2:
The patent implements preliminary charging of capacitors in the multi-stage converter during normal operation, so that voltage conversion can occur instantaneously when needed. The capacitors are pre-charged to appropriate voltage levels through controlled switching, enabling the system to respond immediately to grid demands or storage requirements without the delay associated with traditional transformer-based conversion methods.
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
This solution provides efficient, instantaneous, and bi-directional voltage conversion with reduced energy loss and complexity, enabling effective integration of renewable energy sources into the grid and simultaneous charging/discharging of energy storage systems.
Implementation Method 1
Each stage of the multiple stages comprises a first and a second and a third switch, and a capacitor, wherein the capacitor is coupled to the voltage source by the first and the second switches
Data Source
AI summary
A multi-stage electric voltage converter is disclosed. The converter comprises a voltage source and multiple stages. Each stage of the multiple stages comprises a first and a second and a third switch, and a capacitor, wherein the capacitor is coupled to the voltage source by the first and the second switches and each stage is coupled to a different stage or to an output of the multi-stage electric voltage converter by the third switch so as to allow the capacitor to be charged by the voltage source when the first and the second switches are closed and the third switch is open, and to allow the capacitor to be connected to the output of the multi-stage electric voltage converter when the first and the second switches are open and the third switch is closed.