Bidirectional DC-DC Converter Diode Switch Configuration
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Solution Overview
Problem
Existing bidirectional DC-DC converters face challenges in downsizing and efficiency improvement due to the slow body diode reverse recovery characteristics of high-voltage MOSFETs, which hinder effective power transfer between high-voltage DC power supplies.
Innovation Solution
A bidirectional DC-DC converter design that includes a smoothing capacitor, a transformer, and a control section with a diode and switch configuration that allows for efficient power transfer by using a diode with fast reverse recovery characteristics, reducing switching loss and mitigating the influence of slow body diode reverse recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high-voltage MOSFET is used as the switching device to achieve downsizing and efficiency improvement, then switching speed is improved, but body diode reverse recovery characteristics deteriorate
Solution Approach 1:
The patent divides the power transfer path into two separate controllable paths: one through the MOSFET switching device and another through a parallel diode. This segmentation allows the MOSFET to operate in its optimal switching mode while the diode handles the reverse recovery function, eliminating the trade-off between switching speed and reverse recovery characteristics.
Solution Approach 2:
The patent introduces a parallel diode as an intermediary element that works in conjunction with the MOSFET. This diode serves as a mediator to handle the reverse recovery current, allowing the MOSFET to maintain fast switching characteristics without suffering from slow body diode reverse recovery losses.
2Reliability
If a transformer is used to provide isolation between high-voltage and low-voltage circuits, then electrical isolation is improved, but device complexity increases
Solution Approach 1:
The transformer in the patent serves multiple functions simultaneously: it provides electrical isolation between high-voltage and low-voltage circuits, performs voltage conversion between different voltage levels, and enables bidirectional power flow. This multi-functionality reduces the need for additional separate components, thereby managing complexity while achieving reliable isolation.
3Adaptability or versatility
If bidirectional power conversion is implemented between two DC power supplies, then adaptability is improved, but control complexity increases
Solution Approach 1:
The patent implements dynamic control of the switching devices to enable bidirectional power conversion. The control circuit dynamically adjusts the switching states of the MOSFETs and diodes based on the desired power flow direction, allowing the system to adapt between charging and discharging modes while managing control complexity through coordinated switching patterns.
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 small-size, high-efficiency bidirectional DC-DC converter that effectively transfers power between high-voltage DC power supplies, achieving low switching loss and efficient operation even with high-voltage MOSFETs having slow body diode reverse recovery.
Implementation Method 1
a transformer which magnetically couples the primary winding to the secondary winding
Data Source
AI summary
Disclosed is a small-size, high-efficiency, isolated, bidirectional DC-DC converter. The bidirectional DC-DC converter includes a transformer in which windings are magnetically coupled, switching circuits, a diode which is connected in parallel with a switch, smoothing capacitors, and a control section. First and second DC power supplies, which are connected in parallel with the smoothing capacitors, respectively, provide bidirectional electrical power transfer. When electrical power is to be transferred from the first DC power supply to the second DC power supply, the switch is maintained in the ON state. When, on the other hand, electrical power is to be transferred from the second DC power supply to the first DC power supply, the switch is maintained in the OFF state to prevent a reverse electrical power flow from the first DC power supply.