Interleaved Bidirectional Flyback Converter for Ripple-Stable EV Power
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Solution Overview
Problem
Existing low voltage DC-DC converters in eco-friendly vehicles lack bidirectional power conversion capability and high safety levels, particularly in autonomous driving scenarios, and suffer from inefficiencies and stability issues due to increased loss and noise in power semiconductor components.
Innovation Solution
A bidirectional low voltage DC-DC converter with a parallel interleaving operation of multiple active-clamp flyback converters, controlled by a microcomputer, allowing for both buck and boost modes while minimizing power semiconductor usage and optimizing switching duty to achieve high safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bidirectional active-clamp flyback converter is used, then the number of power semiconductors is minimized, but loss and noise increase leading to reduced efficiency and output stability
Solution Approach 1:
The patent divides a single bidirectional converter into multiple unidirectional buck converters connected in parallel. Each converter handles a portion of the total power, reducing the power semiconductor stress and loss in each individual device while maintaining overall system efficiency and stability.
2Device complexity
If a single bidirectional active-clamp flyback converter is used, then device complexity is reduced, but output voltage and current ripples increase
Solution Approach 1:
Multiple buck converters operate in parallel with interleaved switching sequences. The segmentation of power handling across multiple devices reduces output ripples and improves voltage and current stability while keeping each individual converter relatively simple.
Solution Approach 2:
The patent employs interleaved periodic switching of the parallel converters, where each converter operates at a phase-shifted duty cycle. This periodic action with phase distribution smooths out current and voltage ripples at the output, enhancing overall system stability.
3Reliability
If bidirectional power conversion capability is added to meet safety requirements, then safety level improves, but device complexity and control difficulty increase
Solution Approach 1:
The bidirectional function is segmented into separate buck and boost modes handled by different converter configurations. This segmentation allows independent optimization of each mode while maintaining overall system reliability and safety.
Solution Approach 2:
The parallel interconnected buck converters provide multi-functionality, enabling both bidirectional power conversion and fault tolerance. The same converter structure serves multiple purposes: power conversion, safety compliance, and ripple reduction.
4Power
If power conversion capacity is increased in a single converter, then output power increases, but loss and noise of power semiconductors increase reducing efficiency
Solution Approach 1:
The total power conversion capacity is segmented across multiple parallel converters. Each converter handles a fraction of the total power, keeping power semiconductor stress and associated losses proportional to the individual device capacity rather than the total system capacity, thereby improving overall efficiency.
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 solution enables high safety and improved power conversion performance by reducing output ripples and maintaining essential functions even in fault situations, with the ability to charge high and low voltage batteries bidirectionally, thus meeting the demands of autonomous vehicles.
Implementation Method 1
bidirectional active-clamp flyback converters...connected in parallel and are interleaved and controlled...to enable both a buck operation and a boost operation
Data Source
AI summary
The present disclosure relates to a new bidirectional low voltage DC-DC converter (LDC), that is, a DC-DC converter capable of satisfying a safety level required for an eco-friendly vehicle and an autonomous vehicle and improving power conversion performance, and a method and an apparatus for controlling the same. The LDC proposed in the present disclosure is a new concept bidirectional LDC in which a plurality of converters having the same power circuit topology are subjected to a parallel interleaving operation so as to enable both a buck operation and a boost operation, satisfy a high safety level, and improve power conversion performance. To this end, a plurality of bidirectional active-clamp flyback converters (for example, two or more bidirectional active-clamp flyback converters) are connected in parallel and are interleaved and controlled by a controller (for example, a microcomputer).