Single Drive Power Supply for GaN FETs in DC Converters
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Solution Overview
Problem
Conventional DC power supply devices using wide-bandgap semiconductors like GaN or SiC face challenges in downsizing and simplifying the circuit due to the need for multiple power supplies for FETs, leading to complexity and increased size, especially when dealing with high output voltages in power supply systems for ships or airplanes.
Innovation Solution
A DC power supply device with a single drive power supply for all FET driving circuits, utilizing a relay circuit and sequence circuit to manage the ON/OFF states of FETs in a full-bridge configuration, eliminating the need for a negative power supply to turn off FETs and simplifying the circuit structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple power supplies are used to drive FETs in conventional DC power supply devices, then reliable OFF state control is achieved, but circuit complexity and device size increase
Solution Approach 1:
The patent extracts and eliminates the negative power supply component from the FET driving circuit. By using only a positive power supply with carefully designed gate driving waveforms that naturally create the necessary voltage differences, the complex dual-power-supply structure is simplified to a single power supply system, reducing circuit complexity while maintaining reliable FET control
Solution Approach 2:
The patent changes the driving parameter approach by using time-varying gate voltages with a single positive power supply. Instead of using constant negative voltage to turn off FETs, the invention uses dynamically controlled positive voltage waveforms that create effective voltage differences across the gate-source junction, achieving the same control effect with different electrical parameters
2Reliability
If multiple power supplies are used for FET driving circuits, then proper voltage control is achieved, but device size increases
Solution Approach 1:
The patent merges the functions of multiple power supplies into a single positive power supply system. By combining the voltage generation and control functions into one power supply with intelligent gate driving circuitry, the overall device size is reduced while maintaining the necessary voltage control capabilities for reliable FET operation
Solution Approach 2:
The single positive power supply is designed to perform multiple functions: generating gate drive voltages, creating voltage differences for switching control, and providing necessary current peaks. This multi-functional approach eliminates the need for separate negative power supplies, reducing device size while maintaining comprehensive voltage control
3Reliability
If conventional FET driving methods are used, then stable switching is achieved, but circuit cost increases
Solution Approach 1:
The patent removes the negative power supply component from the circuit, directly reducing component count and manufacturing cost. The extraction is achieved by redesigning the gate driving methodology to use only positive voltage references, eliminating the need for negative voltage generation hardware while maintaining switching stability
Solution Approach 2:
The gate driving circuit is designed to self-generate the necessary voltage differences using only a single positive power supply. The circuit uses capacitive coupling and resistive dividers to create the required voltage swings, making the system self-sufficient without external negative voltage sources, thereby reducing cost while maintaining reliable operation
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 solution allows for a stable OFF state without a negative power supply, reducing circuit complexity and cost, while enabling smaller and more efficient DC power supply devices capable of handling high voltages with lower loss.
Implementation Method 1
a power factor improvement circuit for converting an AC voltage from an AC power supply into a DC voltage by performing full-wave rectification while improving a power factor
Implementation Method 2
a DC/DC converter for converting the DC voltage from the power factor improvement circuit into a low DC voltage to be supplied to a load
Implementation Method 3
each of the plurality of FET driving circuits divides a output voltage from the single drive power supply into positive and negative biases to apply them to corresponding one of the plurality of FETs
Data Source
AI summary
A DC power supply device including a DC/DC converter having FETs each driven by a drive transformer. A voltage from a single drive power supply disposed in common for the FETs is divided into positive and negative biases to be applied to the FETs, and an operational state of the FETs is detected based on voltage signals. A sequence circuit turns on an input from a three-phase AC power supply by driving a relay circuit at a time point when it is confirmed that the FETs have normally started stable ON/OFF operation, and drives a power factor improvement circuit, which converts AC voltage from the three-phase AC power supply into a DC voltage by simultaneously performing full-wave rectification and power factor improvement.