Isolated DC-DC Converter with ZVS Full-Bridge and Current Doubler
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Solution Overview
Problem
DC to DC converters in hybrid or all-electric vehicles face challenges in reducing electromagnetic interference and improving power transfer efficiency while stepping down high voltage from main batteries to lower voltages required for automotive electronics.
Innovation Solution
An isolated DC to DC converter with a full bridge zero voltage switching (ZVS) inverter and a current doubler output stage, utilizing a main transformer and a controller to monitor and control the switching of high and low side switches, forming a resonant circuit to maximize power transfer efficiency and minimize switching losses, while incorporating filters and snubber circuits to reduce electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional DC-DC converter topology is used, then voltage conversion is achieved, but electromagnetic interference increases and power transfer efficiency decreases
Solution Approach 1:
The patent implements zero voltage switching (ZVS) by dynamically controlling the timing of switch operations to occur when the voltage across the switch is zero. This dynamic approach allows the converter to adapt switching moments based on the resonant state of the circuit, minimizing switching losses and reducing electromagnetic interference while maintaining efficient power transfer.
Solution Approach 2:
The patent employs resonant circuits that operate at specific resonant frequencies to enable periodic zero voltage switching. By synchronizing the switching actions with the resonant oscillations of the LC circuits, the converter achieves periodic opportunities for lossless switching, thereby improving power transfer efficiency and reducing electromagnetic interference over each operating cycle.
2Quantity of substance
If high voltage is used in main batteries, then energy storage capacity increases, but electromagnetic interference and switching losses increase
Solution Approach 1:
The patent uses dynamic ZVS control in the full-bridge inverter to manage high voltage from main batteries. By continuously adjusting switch timing to maintain zero voltage conditions during switching, the system can handle high voltage levels for increased energy storage capacity while minimizing switching losses that would otherwise increase with higher voltage.
Solution Approach 2:
The patent introduces resonant LC circuits as intermediary elements between the high voltage source and the switching devices. These resonant circuits act as mediators that transform the voltage waveform to create zero voltage crossing points, enabling lossless switching even when operating from high voltage batteries with increased energy storage capacity.
3Quantity of substance
If high voltage is used in main batteries, then energy storage capacity increases, but electromagnetic interference increases
Solution Approach 1:
The patent implements dynamic ZVS control that adapts switching timing to maintain zero voltage conditions, thereby reducing electromagnetic interference generated during switching transitions. This dynamic approach allows the system to utilize high voltage for increased energy storage capacity while minimizing the electromagnetic interference that would otherwise scale with voltage level.
Solution Approach 2:
The patent converts the potentially harmful high voltage switching transients into beneficial zero voltage switching opportunities by utilizing resonant oscillations. The resonant circuits transform the harsh high voltage switching events into smooth zero voltage transitions, thereby converting what would be sources of electromagnetic interference into efficient, low-interference switching operations while maintaining high energy storage capacity.
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 effectively reduces electromagnetic interference, increases energy efficiency, and provides a reliable power transfer by exploiting resonant circuits and current doubling, enhancing the performance of DC to DC converters in vehicles.
Implementation Method 1
forming a resonant circuit to maximize power transfer efficiency and minimize switching losses
Implementation Method 2
full bridge zero voltage switching (ZVS) inverter
Implementation Method 3
full bridge zero voltage switching (ZVS) inverter and a current doubler output stage, utilizing a main transformer
Implementation Method 4
incorporating filters and snubber circuits to reduce electromagnetic interference
Data Source
AI summary
An isolated DC to DC converter including zero voltage switching and a current doubler. Current sensors are located between a positive input of the DC to DC converter and a current doubler is used in an output stage of the DC to DC converter in order to enable more accurate current sensing in a main transformer to prevent saturation of the transformer core and provide increased efficiency and power output with lower electromagnetic noise. The input of the DC to DC converter is isolated from the output of the DC to DC converter, and the DC to DC converter may be used in a hybrid or all-electric vehicle to provide an accessory bus from a power source of the vehicle.