Bidirectional DC-DC Converter Rectifier Capacitor Cancellation
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Solution Overview
Problem
Conventional unidirectional electric storage battery chargers lack the capability to efficiently operate bidirectionally, delivering energy both from an external power supply to the battery and from the battery to the external network, while maintaining high efficiency and reliability.
Innovation Solution
A bidirectional DC-DC converter design incorporating a full-bridge resonant LLC converter with a cancellation device and an RC circuit to manage capacitor effects, allowing for efficient operation in both charging and discharging directions, and optionally using two converters in parallel for enhanced robustness and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a full-bridge resonant LLC converter is used for unidirectional charging, then efficiency and soft switching are improved, but bidirectional operation capability is lost
Solution Approach 1:
The patent applies dynamics by making the rectifier circuit configurable between two operational states: a first configuration for unidirectional charging operation and a second configuration for bidirectional discharging operation. This dynamic reconfiguration allows the same hardware to adapt to different operational modes, resolving the contradiction between optimized unidirectional performance and bidirectional capability.
Solution Approach 2:
The patent implements universality by designing the rectifier circuit to perform multiple functions through configuration changes. The same rectifier circuit serves both as a standard rectifier during charging and as an active element enabling bidirectional power flow during discharging, eliminating the need for separate circuits for each function.
2Adaptability or versatility
If capacitor structures are added to enable bidirectional operation, then bidirectional capability is improved, but device complexity increases
Solution Approach 1:
The patent applies merging by integrating the bidirectional enabling capability directly into the existing rectifier circuit structures. Rather than adding completely separate bidirectional conversion circuits, the invention combines the bidirectional functionality with the existing capacitor and transistor elements already present in the full-bridge configuration, thereby reducing overall system complexity.
Solution Approach 2:
The patent makes existing components universal by enabling the rectifier circuit to serve dual purposes: standard rectification during charging and active bidirectional power conversion during discharging. This multi-functionality reduces the need for additional dedicated components for bidirectional operation.
3Adaptability or versatility
If bidirectional operation is implemented without capacitor management, then bidirectional capability is achieved, but overvoltages and reliability deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-configuring the rectifier circuit in different states depending on the operational mode. Before bidirectional discharging begins, the circuit is预先 configured to the appropriate state, ensuring that voltage management is already in place before potential overvoltage conditions occur, thereby preventing rather than reacting to reliability issues.
Solution Approach 2:
The patent implements feedback mechanisms through the configurable rectifier circuit that monitors and responds to operational conditions. The circuit can switch between configurations based on the direction of power flow and voltage levels, providing automatic feedback control that maintains reliability during bidirectional operation by preventing overvoltage conditions.
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 a robust, cost-effective bidirectional charger with improved efficiency and reduced overvoltages, capable of handling high currents and ensuring reliable operation in both charging and discharging modes.
Implementation Method 1
an LLC circuit, comprising a capacitor and two inductors, excited by said square signal
Implementation Method 2
a transformer transmitting said signal coming from the LLC circuit
Implementation Method 3
a rectifier rectifying the signal transmitted by the transformer
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention concerns a DC-DC conversion device (1) for a charger of a battery (26) of electrical accumulators connected to an electrical grid, capable of operating in a bidirectional manner, comprising at least one resonant full-bridge LLC converter (20), comprising: - a rectifier (24) rectifying the signal amplified by the transformer (23), said rectifier (24) being formed by a full bridge of four parallel structures (240, 240', 240", 240"'), each formed of a transistor (301), a diode (302) and a capacitor (303) mounted in parallel; characterised in that each parallel structure (240, 240', 240", 240"') of the rectifier (24) comprises a device (40) for cancelling the effect of the capacitor (303) of the associated parallel structure (240, 240', 240", 240"') when the DC-DC conversion device (1) operates in indirect mode.