Traction Battery Heating via Reverse-Operated GaN/SiC Transistors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for heating traction batteries in electric or hybrid vehicles using waste heat from power semiconductors, such as SiC transistors, face issues with local overheating due to the cell structure, leading to inefficiencies and potential short circuits.
Innovation Solution
A device and method utilizing GaN or SiC power transistors operated in reverse mode with extended gate-source voltage withholding, coupled to a cooling circuit, to generate waste heat efficiently, with control mechanisms adjusting the operation based on battery temperature and power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power semiconductors are operated in forward mode with reduced gate-source voltage to generate heat, then heating power is improved, but local overheating of the power semiconductor occurs
Solution Approach 1:
The patent applies reverse operation of the power semiconductor device instead of forward mode operation. By operating the transistor in reverse direction with extended dead time, the heat generation occurs in a different region of the device structure, avoiding the local overheating problems associated with forward mode operation while still achieving the desired heating effect in the battery.
Solution Approach 2:
The patent changes the operational parameters of the power semiconductor by extending the dead time period during reverse operation. This parameter modification allows the device to operate in a regime that generates sufficient heat for battery warming without causing local overheating, as the extended duration distributes the thermal load differently compared to traditional forward mode heating.
2Productivity
If gate-source voltage is withheld for extended period to generate more heat, then heating efficiency is improved, but risk of short circuit increases
Solution Approach 1:
The patent utilizes reverse operation mode where the body diode characteristics are exploited to allow extended gate-source voltage withholding without creating short circuit conditions. In reverse operation, the device structure naturally prevents the short circuit risk that would occur in forward mode during extended dead time, enabling safer and more efficient heat generation.
Solution Approach 2:
The patent converts what would normally be a harmful condition (extended dead time causing potential short circuits) into a beneficial heating mechanism. By operating in reverse mode, the body diode's forward voltage drop during the extended dead time is transformed into a useful heat source for battery warming, turning a potential reliability issue into an efficiency advantage.
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
Enhances heating efficiency by leveraging the reverse conductivity of GaN and SiC transistors to generate significant waste heat without short circuits, effectively raising battery temperature to desired levels.
Implementation Method 1
the at least one GaN or SiC power transistor is operated in reverse... the time in which the GaN or SiC power transistor is operated in reverse without gate-source voltage is extended... for the very efficient generation of a significant amount of waste heat
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a device for heating a traction battery (2) for an electric or hybrid vehicle, wherein the device comprises at least one device (7) for sensing or determining the temperature of the traction battery (2), a cooling circuit (9), and at least one electrical component with at least one GaN power transistor (11) or SiC power transistor, wherein the traction battery (2) and the electrical component are thermally coupled to the cooling circuit (9), wherein in one operating state the at least one GaN or SiC power transistor is operated in reverse, and wherein a control device (10) of the at least one GaN or SiC power transistor is configured to withhold gate-source voltage to the GaN or SiC power transistor in reverse for a predetermined time, depending on the temperature of the traction battery (2), wherein the predetermined time is greater than an initial delay time.as well as a procedure.