Transformer-Coupled Power Converter With Fewer Active Switching Elements
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Solution Overview
Problem
Conventional bidirectional power converters require a total of three full-bridge circuits, making it difficult to reduce the number of active components and increasing conduction losses.
Innovation Solution
A power converter design that includes a transformer, direct-current-side and alternating-current-side circuits with capacitors and inductors, and a bridge circuit configuration that reduces the number of active components by using a series connection of switching elements and parallel connection of buffer circuits to manage current continuity and suppress surge voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three full-bridge circuits are used for bidirectional power conversion, then reliable power conversion between AC and DC is achieved, but the number of active components increases and conduction losses increase
Solution Approach 1:
The patent merges the functions of three separate full-bridge circuits into a single full-bridge circuit by utilizing the transformer's magnetic coupling. The full-bridge circuit generates high-frequency AC voltage that is transformed and rectified to achieve bidirectional power conversion, eliminating the need for multiple bridge circuits while maintaining conversion reliability.
Solution Approach 2:
The single full-bridge circuit performs multiple functions: it converts DC to high-frequency AC, and through the transformer and rectifier circuits, enables both AC-to-DC and DC-to-AC conversion. The buffer circuits on both sides provide additional multi-functionality by managing voltage surges and ensuring current continuity during bidirectional operation.
2Reliability
If three full-bridge circuits are used for bidirectional power conversion, then complete AC-DC and DC-AC conversion is achieved, but conduction losses increase
Solution Approach 1:
By combining multiple conversion stages into a single full-bridge circuit with transformer coupling, the patent reduces the number of conduction paths and active components through which energy is lost. The high-frequency operation enabled by the single bridge circuit also reduces switching losses compared to lower-frequency multi-bridge configurations.
Solution Approach 2:
The patent employs high-frequency switching in the full-bridge circuit, which reduces the size of magnetic components and improves efficiency. The buffer circuits are designed to minimize voltage surge durations, reducing energy loss during transient states. The rectifier circuits are optimized to minimize forward voltage drops, further reducing conduction losses.
3Productivity
If buffer circuits are added to ensure current continuity and suppress surge voltages, then transformer efficiency is enhanced, but device complexity increases
Solution Approach 1:
The buffer circuits are positioned on both the AC and DC sides of the transformer to proactively manage voltage surges and current discontinuities before they can negatively impact the transformer. This preliminary protection enhances transformer efficiency by preventing harmful electrical transients while the symmetry of the design keeps added complexity manageable.
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 design reduces the number of active components, minimizes conduction losses, and enhances the efficiency of the transformer by ensuring current continuity and suppressing surge voltages, thereby improving the overall performance of the power conversion process.
Implementation Method 1
The transformer includes a direct-current-side winding and an alternating-current-side winding
Implementation Method 2
A series connection of the first upper arm switching element and the first lower arm switching element and a series connection of the second upper arm switching element and the second lower arm switching element form a bridge circuit
Implementation Method 3
The direct-current-side circuit includes a direct-current-side inductor, a rectification switching element
Data Source
AI summary
A power converter includes an alternating-current-side circuit, a direct-current-side inductor, an alternating-current-side inductor, a direct-current-side circuit, a controlling unit, a transformer, a direct-current-side capacitor, and an alternating-current-side capacitor. The alternating-current-side circuit includes an alternating-current-side buffer circuit and a bridge circuit, and is connected to an alternating-current-side winding of the transformer via the alternating-current-side capacitor. The direct-current-side circuit includes a direct-current-side buffer circuit and a rectification switching element, and is connected to a direct-current-side winding of the transformer via the direct-current-side capacitor. The controlling unit controls switching of the switching elements.