Resonant switched capacitor converter
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Solution Overview
Problem
Existing DC-DC power converters face inefficiencies and high power losses due to hard-switching techniques in switched capacitor circuits and the need for transformers in resonant converters, which increase complexity and cost while reducing power density.
Innovation Solution
A DC-DC power converter utilizing a coupled inductor with flying capacitors and a network of switches that operates in both soft-switching and hard-switching modes, employing zero voltage and zero current switching to minimize power loss and reduce transformer reliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hard-switching technique is used in switched capacitor circuit, then circuit complexity is reduced and transformer is eliminated, but power loss increases and efficiency decreases
Solution Approach 1:
The switching cycle is divided into multiple distinct phases (first phase with first and second states, second phase with third and fourth states), where different switching techniques are applied in different phases. This segmentation allows the circuit to achieve both reduced complexity and lower power loss by using hard-switching in some phases and soft-switching in others.
Solution Approach 2:
The converter operates with periodic switching cycles that alternate between hard-switching and soft-switching modes. The driver applies different sequences of states periodically, enabling the circuit to benefit from both hard-switching simplicity and soft-switching efficiency at different intervals.
2Loss of energy
If soft-switching technique with resonant tank is used, then power loss decreases and efficiency improves, but device complexity increases due to transformer requirement
Solution Approach 1:
The invention extracts and eliminates the transformer component from the resonant converter while retaining the essential soft-switching functionality. By using flying capacitors and a coupled inductor instead of a transformer, the circuit achieves soft-switching benefits without the complexity and losses associated with transformer-based resonant tanks.
Solution Approach 2:
The patent creates a simplified version of the resonant tank using flying capacitors and coupled inductors that copies the soft-switching behavior of traditional transformer-based resonant converters. This alternative implementation achieves similar electrical characteristics without requiring a transformer.
3Reliability
If transformer is used in resonant converter, then soft-switching is achieved, but AC winding loss increases due to large average AC current
Solution Approach 1:
The invention replaces the expensive and lossy transformer with a simpler coupled inductor structure that has lower winding losses. The coupled inductor with flying capacitors provides the necessary soft-switching functionality with significantly reduced AC winding losses, effectively substituting a high-loss component with a lower-loss alternative.
4Ease of manufacture
If switched capacitor circuit without transformer is used, then production cost decreases and AC winding power loss is reduced, but power density becomes low
Solution Approach 1:
The converter employs dynamic switching sequences that adapt between different operational states within each switching cycle. This dynamic operation allows the circuit to achieve higher power density by optimizing the timing and duration of different phases, enabling the transformerless design to deliver more power per unit volume than conventional static switched capacitor circuits.
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 converter achieves higher efficiency and power density with reduced component size and manufacturing costs by combining soft-switching and hard-switching modes, minimizing voltage and winding losses.
Implementation Method 1
a coupled inductor having a first winding and a second winding
Implementation Method 2
employing zero voltage and zero current switching to minimize power loss
Data Source
AI summary
A DC-DC power converter has a ground terminal, an input terminal for receiving an input voltage and an output terminal for providing an output voltage with a target conversion ratio. The power converter includes a coupled inductor having a first winding and a second winding coupled to the output terminal; a first flying capacitor coupled to a first inductor and to the second winding; a second flying capacitor coupled to a second inductor and to the first winding; an input capacitor coupling the input terminal to the ground terminal; an output capacitor coupling the output terminal to the ground terminal; a network of switches; and a driver adapted to drive the network of switches with a sequence of states during a drive period, wherein the sequence of states forms a switching cycle.