Bidirectional Switching AC-DC Converter with LC Resonance
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Solution Overview
Problem
Conventional AC/DC converters experience significant losses due to diodes and switching elements, particularly as load capacity increases, necessitating a reduction in diode count and switching losses.
Innovation Solution
A power supply device utilizing a multi-resonant half-bridge switching circuit with bidirectional switching elements and an LC resonant circuit, along with a control circuit for synchronous rectification, eliminates the need for diodes by directly synchronously rectifying AC power using bidirectional switching elements, reducing switching losses and diode-related losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of diodes is increased to handle higher load capacity, then the power supply can support higher loads, but the loss caused by diodes increases proportionally
Solution Approach 1:
The patent extracts and removes the diode bridge rectifier from the conventional AC/DC converter circuit. Instead of using traditional diodes for rectification, the invention employs bidirectional switching elements (Q1, Q2) that perform both switching and rectification functions, thereby eliminating the need for separate diode components and reducing diode-related losses.
Solution Approach 2:
The bidirectional switching elements serve multiple functions: they act as both switching elements for high-frequency operation and as rectifying elements for AC-to-DC conversion. This multi-functionality replaces the separate roles previously fulfilled by diodes and switching elements, reducing overall component count and energy loss.
2Volume of moving object
If the switching frequency is increased to miniaturize the transformer and inductor, then the power supply size is reduced, but the switching loss increases
Solution Approach 1:
The patent employs resonance principles where the LC resonant circuit (comprising inductor Lr and capacitors Cv, Ci) is tuned to resonate at the switching frequency. This resonant operation allows the circuit to operate efficiently at high frequencies with minimized switching losses, as the resonant oscillation reduces the stress on switching elements and minimizes energy dissipation during switching transitions.
Solution Approach 2:
The invention changes the operating parameters by implementing zero voltage switching (ZVS) and zero current switching (ZCS) conditions through the multi-resonant half-bridge circuit. By carefully controlling the timing and phase of switching operations relative to the resonant oscillations, the circuit achieves soft switching conditions that dramatically reduce switching losses while maintaining high-frequency operation.
3Ease of manufacture
If conventional diodes are used for rectification, then the circuit is simple to implement, but the loss becomes significant especially at high load capacities
Solution Approach 1:
The patent replaces the passive diode-based rectification system with an active switching-based rectification system. The bidirectional switching elements, controlled by gate driving signals from the control circuit, actively manage current flow direction and timing, replacing the passive unidirectional conduction of diodes. This active control enables more efficient power conversion with reduced losses.
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 configuration significantly reduces overall losses, enabling a high-efficiency power supply with minimized diode and switching element losses, allowing for a more compact and efficient design.
Implementation Method 1
A resonant circuit composed of an inductor Lr and capacitors Cv and Ci is connected to the primary coil Np50 of the transformer 51
Implementation Method 2
a control circuit for inputting gate driving signals to the bidirectional switching elements... perform synchronous rectification by inputting, during a half cycle of the AC current, a first gate driving signal
Implementation Method 3
a multi-resonant half-bridge DC/DC converter performs a voltage conversion. The DC/DC converter includes a multi-resonant half-bridge switching circuit composed of two switching elements Q51 and Q52 connected to a primary coil Np50 of a transformer 51
Data Source
AI summary
A power supply device includes a transformer; a series circuit of two bidirectional switching elements connected between terminals of the commercial power supply and having a rectification function and a switching function; an LC resonant circuit connected between a primary coil of the transformer and both ends of one of the bidirectional switching elements; a rectifying element connected to a secondary coil of the transformer; and a control circuit for inputting a gate driving signal to the bidirectional switching elements. The power supply device performs synchronous rectification from the bidirectional switching elements.