Three-Level Rectification DC/DC Converter for 800V Bidirectional Gain
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Solution Overview
Problem
Conventional DC/DC converters face challenges in achieving high-voltage gain and bidirectional operation efficiently, particularly at 800V, due to limitations with SiC and GaN components, and existing solutions like dual-active-bridge and LLC circuits suffer from complexity and EMI issues.
Innovation Solution
A three-level rectification DC/DC converter with a resonant circuit, featuring a primary circuit, resonant tank circuit, and secondary circuit with a switch bridge arm and capacitor bridge arm, allowing energy storage through short-circuiting the secondary circuit to achieve high voltage gain and bidirectional operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If SiC component with 1200V withstand voltage is used to achieve 800V application, then the voltage requirement is met, but the cost increases and high dv/dt causes EMI problems
Solution Approach 1:
The patent divides the high-voltage circuit into multiple levels (three-level rectification) where each switch only needs to withstand a portion of the total voltage (400V) rather than the full 800V. This segmentation allows using lower-voltage, lower-cost switches while meeting the overall voltage requirement, and reduces dv/dt stress on individual devices thereby minimizing EMI.
Solution Approach 2:
The patent transitions from a conventional single-level high-voltage circuit to a multi-level topology, adding a vertical dimension to voltage distribution. By creating intermediate voltage levels through series-connected switches and capacitors, the system achieves high output voltage gain while each component operates at lower voltage stress, reducing EMI and cost.
2Adaptability or versatility
If dual-active-bridge circuit with multiple phase shift technique is used to achieve wide output voltage range, then the voltage range requirement is met, but the control becomes complicated and high turn-off current causes high turn-off stress and EMI
Solution Approach 1:
The patent employs variable frequency control instead of fixed-frequency multiple phase shift control. The switching frequency dynamically adjusts based on the required output voltage, simplifying the control strategy while maintaining wide output voltage range capability. This dynamic approach eliminates the need for complex multi-phase shift coordination and reduces turn-off current stress.
3Loss of energy
If LLC circuit with variable frequency control is used to achieve zero voltage switching, then the switching loss is reduced, but the bidirectional work requirement cannot be met
Solution Approach 1:
The patent designs a universal DC/DC converter topology that can operate bidirectionally (both P2V and V2P modes) while maintaining zero-voltage switching characteristics. The three-level rectification circuit combined with full-bridge inverter and resonant tank enables the system to function as both charger and discharge unit, providing multi-functionality that LLC circuits lack.
4Power
If conventional DC/DC converter is used at 800V, then the voltage level is achieved, but high voltage gain and efficiency are difficult to achieve simultaneously
Solution Approach 1:
The patent utilizes resonant oscillation in the tank circuit (Lr-Cr) to achieve soft switching conditions. By operating at or near the resonant frequency, the circuit experiences minimal losses and high efficiency while delivering high output voltage. The resonant behavior enables energy to oscillate between inductor and capacitor, reducing switching losses and 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 efficient high-voltage gain and bidirectional operation while reducing EMI and component stress, allowing for the use of lower withstand voltage switches, thus lowering costs and simplifying heat dissipation design.
Implementation Method 1
the three-level rectification DC/DC converter has the characteristic of storing energy through short-circuiting the secondary circuit thereof
Implementation Method 2
A primary winding of the transformer is coupled between the first and second primary terminals. A secondary winding of the transformer is coupled between a first secondary terminal and a second secondary terminal of the resonant tank circuit
Data Source
AI summary
The present disclosure provides a three-level rectification DC/DC converter including primary and secondary circuits and a resonant tank circuit. A voltage between two primary terminals is a first voltage. The secondary circuit includes a switch bridge arm and a capacitor bridge arm. The switch bridge arm includes four switches serially connected. A node between the first and second switches is connected to the first secondary terminal, a node between the third and fourth switches is connected to the second secondary terminal, and a node between the second and third switches is connected between two capacitors of the capacitor bridge arm. In two consecutive periods of the first voltage, the first and fourth switches are in an on state for a preset time length after two falling edges respectively, and the second and third switches are in the on state for the preset time length after two rising edges respectively.