Galvanically Isolated Gate Driver With Reverse Power Transfer
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Solution Overview
Problem
Conventional insulated gate drivers face challenges in efficiently transferring power from a high voltage side to a low voltage side due to limited power transmission capability and high power loss, requiring separate voltage supplies and occupying significant area, while also needing accurate gate voltage supply for SiC MOSFETs.
Innovation Solution
The insulated gate driver design includes an isolation structure that galvanically isolates the high and low voltage sides, allowing power to be transferred from the high voltage side to the low voltage side over this structure for powering logic circuitry, reducing power dissipation and area requirements, and using techniques like modulated load impedance and frequency modulation for signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power is transmitted from low voltage side to high voltage side using coreless transformers, then galvanic isolation is achieved, but power transmission capability is limited and power loss increases significantly
Solution Approach 1:
The patent inverts the conventional power transmission direction by transmitting power from the high voltage side to the low voltage side through the isolation structure, rather than from low voltage to high voltage. This inversion reduces power loss because the high voltage side has lower current and thus lower I²R losses in the isolation structure. The high voltage side also has sufficient power headroom to supply the low voltage side's power requirements efficiently.
Solution Approach 2:
The patent changes the voltage and power parameters by providing an external power supply to the high voltage side and transmitting a fraction of this power to the low voltage side. This parameter change enables efficient power transmission by operating in a regime where the isolation structure experiences lower losses, while still meeting the power requirements of the logic circuitry on the low voltage side.
2Power
If transformers with magnetic cores are used for power transmission, then power transmission capability increases, but device area increases significantly
Solution Approach 1:
By inverting the power transmission direction to flow from high voltage to low voltage side, the patent achieves efficient power transmission without requiring large magnetic cores. The high voltage side's lower current requirements allow the use of smaller isolation structures (such as coreless transformers or capacitive couplings) that occupy minimal area while still transmitting sufficient power to the low voltage side.
3Power
If separate voltage supplies are used for input and output sides, then power requirements are met, but device complexity and area increase
Solution Approach 1:
The patent merges the power supply functions by providing a single external power supply to the high voltage side and using the isolation structure to simultaneously achieve both power transmission and galvanic isolation. The low voltage side's power requirements are met through the transmitted power fraction, eliminating the need for a separate power supply on the low voltage side and reducing overall device complexity.
Solution Approach 2:
The isolation structure serves multiple functions simultaneously: it provides galvanic isolation between the high voltage and low voltage sides, transmits power from the high voltage side to the low voltage side, and enables signal transmission. This multi-functionality eliminates the need for separate components for each function, reducing device complexity and area.
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 reduces power dissipation and area requirements, enabling efficient power transfer and accurate signal communication between voltage sides, suitable for a broad range of applications including SiC MOSFET modules, while ensuring safe-torque-off and calibration for improved system accuracy and performance.
Implementation Method 1
an isolation structure galvanically isolating the input side and the output side from one another, wherein the output side is configured to transfer a fraction of the power received at the power supply pin to the input side over the isolation structure
Data Source
AI summary
A gate driver includes: an input pin for receiving switching control information from a controller; an output pin for driving a control terminal of a power transistor; a power supply pin for receiving power from an external supply; an input side electrically connected to the input pin; an output side electrically connected to the output pin and the power supply pin; and an isolation structure galvanically isolating the input side and the output side from one another. The output side is configured to transfer a fraction of the power received at the power supply pin to the input side over the isolation structure for powering the input side. The input side is configured to convey the switching control information received at the input pin to the output side over the isolation structure. A power electronic system that includes the gate driver is also described.