Buck-Boost Power Converter With Coupled Bridges for Wide Voltage Range
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Solution Overview
Problem
Current DC-DC converters for wide input voltage ranges are inefficient and bulky, particularly in high power ratings and high power density applications, leading to increased switching and conduction losses, complex gate driver circuitry, and scalability issues.
Innovation Solution
A bidirectional power converter with a first and second bridge circuit, each equipped with magnetically coupled transformer windings, and a controller to manage switch states for efficient conversion, allowing operation in both buck and boost modes, using 4-quadrant switches for bidirectional voltage blocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional four-switch buck-boost topology is used for wide input voltage range conversion, then voltage step-up and step-down capability is achieved, but switching losses increase when voltage gain is near 1 and conduction losses increase when voltage gain deviates from 1
Solution Approach 1:
The power conversion function is segmented into two independent full-bridge circuits (first and second bridge circuits) with magnetically coupled transformer windings. Each bridge circuit can operate independently or in combination, allowing the system to optimize the active switching devices based on the required voltage gain, thereby reducing both switching and conduction losses across the entire operating range.
Solution Approach 2:
The transformer with magnetically coupled windings serves multiple functions: it enables both galvanic isolation and voltage transformation, and the magnet coupling allows energy transfer between primary and secondary sides without direct electrical connection. This multi-functionality reduces the need for additional components and simplifies the overall topology while maintaining wide voltage conversion capability.
2Adaptability or versatility
If conventional inverting buck-boost converter is used for negative input voltage applications, then voltage inversion is achieved, but a bulky inductor is required and large RMS currents result in increased losses
Solution Approach 1:
The bulky magnetic inductor is replaced with a magnetically coupled transformer system where energy transfer is achieved through magnetic coupling between transformer windings rather than a large standalone inductor. This substitution reduces the size and weight of magnetic components while maintaining the ability to handle negative input voltages through bidirectional switch operation.
3Power
If magnetically coupled converters with transformer turns ratio are used for voltage conversion, then voltage gain is achieved, but efficiency and power density do not improve for wide input voltage ranges
Solution Approach 1:
The system dynamically adapts its operating mode based on the input voltage and required output voltage. The controller can switch between different bridge circuit configurations and adjust the duty cycles of switching devices to optimize efficiency across wide input voltage ranges, rather than relying on a fixed transformer turns ratio. This dynamic operation reduces losses by keeping switching devices in optimal states for each operating condition.
4Power
If conventional DC-DC converters are scaled to higher power ratings, then power capacity increases, but the solution becomes bulky and complex requiring paralleling of stages
Solution Approach 1:
The two full-bridge circuits are merged into a single integrated converter system with magnetically coupled transformer windings. This unified structure achieves higher power ratings through the combined capability of both bridge circuits without requiring parallel connection of separate converter stages, thereby reducing overall system complexity while scaling power capacity.
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
Achieves high efficiency and power density with reduced component stress and losses, enabling scalable power ratings without the need for paralleling stages, suitable for applications like telecom base station power amplifiers.
Implementation Method 1
The first transformer winding may be magnetically coupled to the second transformer winding
Implementation Method 2
an inductor operative to receive the input voltage; and a second bridge circuit. The inductor provides coupling of the input voltage source to the second bridge circuit
Data Source
AI summary
An apparatus as discussed herein can be configured to include a first bridge circuit operative to receive an input voltage supplied by an input voltage source. An inductor in the apparatus also receives the input voltage. The apparatus can be configured to include a second bridge circuit. The inductor provides coupling of the input voltage source to the second bridge circuit. The second bridge circuit produces an output voltage to power a load.