Battery Disconnect Circuit Gate Voltage Control for Transistor Lifetime
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Solution Overview
Problem
The existing electronic devices used in battery disconnect units for hybrid and electric vehicles face reduced transistor lifetime due to high gate voltage, leading to increased conduction losses and thermal loads, especially during high currents and prolonged operations.
Innovation Solution
The method involves dynamically adjusting the gate voltage of transistors based on current flow and temperature to minimize conduction losses, with increased voltage during high currents and reduced voltage during low currents, and employing negative gate voltage for quicker switching and blocking states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high gate voltage is applied to the transistor to ensure reliable switching and current blocking, then switching reliability is improved, but conduction losses increase and transistor lifetime decreases
Solution Approach 1:
The patent implements dynamic gate voltage adjustment where the control unit modifies the gate voltage level based on real-time operating conditions. During high-current operation, the gate voltage is optimized to minimize conduction losses, while during low-current operation, it is adjusted to ensure reliable current blocking. This dynamic adaptation resolves the contradiction by allowing the system to achieve both low losses and high reliability at different operational moments rather than using a fixed high gate voltage throughout.
Solution Approach 2:
The patent changes the gate voltage parameter adaptively based on operating conditions such as current magnitude and temperature. The control unit monitors these parameters and adjusts the gate voltage accordingly - using lower gate voltages during high-current conduction phases to reduce losses, and higher gate voltages during off-states to ensure reliable blocking. This parameter change strategy enables the system to optimize both conduction efficiency and switching reliability under different operating scenarios.
2Reliability
If high gate voltage is applied to the transistor to ensure current blocking, then current blocking capability is improved, but transistor lifetime decreases due to prolonged electrical stress
Solution Approach 1:
The system dynamically adjusts gate voltage based on real-time monitoring of current flow and temperature. During off-states when current blocking is required, the control unit applies sufficient gate voltage to ensure reliable blocking. During on-states when current flows, the gate voltage is reduced to minimize electrical stress on the transistor. This dynamic approach ensures current blocking capability is maintained only when necessary, thereby extending transistor lifetime by reducing prolonged exposure to high voltage stress.
Solution Approach 2:
The patent implements periodic adjustment of gate voltage in synchronization with the switching cycles of the transistor. The control unit periodically monitors operating conditions and adjusts gate voltage levels accordingly - applying high gate voltage during off-periods for reliable blocking, and reducing it during on-periods to minimize stress. This periodic action pattern ensures blocking capability is maintained during required periods while reducing overall cumulative stress on the transistor, thereby extending its operational life.
3Loss of energy
If gate voltage is increased to reduce conduction losses during high current, then energy efficiency is improved, but thermal load on the transistor increases
Solution Approach 1:
The patent incorporates a feedback mechanism where the control unit continuously monitors the temperature of the transistor and adjusts the gate voltage accordingly. When temperature rises above a threshold during high-current operation, the control unit reduces the gate voltage to lower conduction losses and thereby reduce further temperature increase. This feedback loop creates a self-regulating system that balances energy efficiency with thermal management, preventing excessive thermal load while maintaining acceptable conduction losses.
Solution Approach 2:
The system dynamically changes the gate voltage parameter based on temperature conditions. During high-current operation, if temperature remains within acceptable limits, the gate voltage is optimized to minimize conduction losses. However, when temperature approaches critical thresholds, the gate voltage is reduced to decrease both conduction losses and the resulting thermal generation. This parameter change strategy adapts the electrical characteristics to thermal conditions, resolving the contradiction between energy efficiency and thermal load management.
Data Source
AI summary
A method for controlling a device for enabling and interrupting a flow of electric current between a battery and a load or a charging device. The device includes at least one transistor. The gate voltage is set on the basis of a current flowing through the at least one transistor and/or a temperature of the at least one transistor. A circuit device is also described.