Thermal Balancing of Parallel Transistors via Gate Resistance Control
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Solution Overview
Problem
In parallel transistor systems, manufacturing differences lead to varying transistor performance, making it challenging to balance temperature and prevent uneven wear and aging, resulting in overloading and reduced efficiency, especially in motor controllers for vehicles like aircraft.
Innovation Solution
An electronic circuit with temperature sensors and a controller that adjusts gate and emitter resistances to balance current through each transistor, ensuring equal thermal conditions and prolonged lifespan by monitoring temperature differences and adjusting resistances accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional current balancing is used to force equal current through parallel transistors, then current distribution is simplified, but transistors with higher on-resistances experience overloading and higher temperatures leading to uneven wear and reduced reliability
Solution Approach 1:
The patent applies local quality by adjusting the current through each transistor individually based on its specific thermal conditions. Temperature sensors monitor each transistor's temperature, and the controller modifies gate drive signals selectively for each transistor to equalize their operating temperatures, rather than applying uniform current distribution to all transistors.
Solution Approach 2:
The patent changes the operating parameters of each transistor dynamically by adjusting gate drive signals based on real-time temperature measurements. The controller modifies parameters such as gate voltage or current to control the current flow through each transistor, thereby adjusting their operating temperatures to achieve thermal balance.
2Reliability
If motor controllers are overbuilt to handle maximum requirements, then reliability is improved, but device weight and complexity increase and flexibility decreases
Solution Approach 1:
The patent applies dynamics by enabling motor controllers to adapt their current distribution dynamically based on real-time thermal conditions of parallel transistors. The controller continuously monitors temperatures and adjusts gate drive signals to optimize current sharing, allowing the system to operate efficiently across varying load conditions without requiring overbuilding for maximum capacity.
Solution Approach 2:
The patent enhances universality by designing a motor controller system that can efficiently handle various operating conditions and configurations. The thermal balancing mechanism allows the same controller design to reliably manage different numbers of parallel transistors and varying load requirements, reducing the need for multiple specialized controller designs.
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 effectively thermally balances parallel transistors, preventing uneven wear and aging, leading to a more efficient and flexible motor controller design that can handle various motor loads without overbuilding, thus enhancing performance and longevity.
Implementation Method 1
Temperature sensors are thermally coupled to each of the transistors for producing a temperature output signal indicative of a measured temperature of each of the transistors
Implementation Method 2
provide controller outputs to vary a gate resistance RG and a gate emitter resistance RGE associated with each of the transistors. The gate resistance RG and the gate emitter resistance RGE vary current to each of the transistors
Implementation Method 3
Transistor parameters such as on-resistance and gate capacitance are subject to the effects of temperature, aging, and defect
Data Source
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AI summary
A system and method for prolonging and equalizing the effective life of a plurality of transistors operating in parallel. The temperature of each transistor is measured and compared with the average temperature of the transistor system. A temperature difference is determined between the average temperature of the transistors and the measured temperature of each of the transistors. The gate resistance and the gate emitter resistance of each transistor is varied based on the temperature differences to control the measured temperature of each transistors by controlling current through each transistor thereby thermally balancing the transistors.