Heated Cooling Element for Frequency Converter Semiconductor Stress
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Solution Overview
Problem
Semiconductor components in frequency converters experience mechanical stress due to temperature variations caused by cyclic loads, leading to premature aging, as different parts have varying thermal expansion coefficients and time constants, which existing cooling methods like forced air or liquid cooling cannot effectively mitigate.
Innovation Solution
A method involving the use of resistive elements attached to the cooling elements to maintain a higher minimum temperature, reducing temperature variations by heating the cooling element when the component is not under high power load, and controlling forced cooling based on load cycles to minimize temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If forced air or liquid cooling is used to maintain low maximum temperature, then the maximum temperature of the semiconductor component is reduced, but the temperature variation (difference between maximum and minimum temperature) is not decreased, so semiconductor stresses during cyclic loads are not adequately managed
Solution Approach 1:
The cooling element is preheated using a resistive element before the semiconductor component is subjected to cyclic loads. This preliminary heating action ensures that the cooling element starts at an elevated temperature, which reduces the temperature variation range when the semiconductor operates under load cycles, thereby reducing thermal stress on the semiconductor components.
Solution Approach 2:
The invention changes the temperature parameter of the cooling element by using a resistive heating element to elevate its temperature. This parameter change (from ambient temperature to elevated temperature) modifies the thermal characteristics of the system, reducing the temperature swing experienced by the semiconductor component during cyclic operation and thereby reducing thermal stress.
2Temperature
If constant cooling is used regardless of semiconductor temperature, then the maximum temperature is controlled, but energy is wasted when the semiconductor is not generating high heat, and the temperature variation is not optimized
Solution Approach 1:
The cooling system operates periodically rather than continuously. The resistive heating element is activated during periods when the semiconductor is not generating high heat, preheating the cooling element in advance. This periodic action optimizes energy usage by heating only when necessary to reduce future temperature variations, rather than maintaining constant cooling or heating.
3Reliability
If the cooling element is heated to reduce temperature variation, then semiconductor stresses are reduced, but additional energy is required for heating the cooling element
Solution Approach 1:
The invention converts the harmful effect of temperature variation into a beneficial effect by using resistive heating to preheat the cooling element. The heating energy, which might seem like an additional burden, actually reduces the overall temperature swing and thermal stress on the semiconductor, extending its lifespan. The energy invested in heating is offset by the reduction in thermal stress damage.
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
Significantly reduces semiconductor stresses by maintaining a stable temperature profile, extending the service life of components without overrating the cooling system, and minimizing thermal expansion risks through controlled temperature management.
Implementation Method 1
one or more resistive elements are attached to the cooling element... The resistive elements are used to heat the cooling element
Implementation Method 2
The function of the baseplate is to conduct heat generated in the component to cooling elements
Implementation Method 3
heat is transferred away from the device to cool the components of the device... utilizing forced air or liquid in connection with the heat sink
Implementation Method 4
The different parts of the semiconductor components have not only different temperature time constants, but also different thermal expansion coefficients. Because the parts of a semiconductor component are tightly together, often soldered, mechanical forces occur between them due to expansions of different sizes
Data Source
AI summary
A method of reducing thermal stresses of a semiconductor component in a frequency converter, an arrangement in a frequency converter, and a frequency converter, wherein the semiconductor component is attached to a cooling element for cooling the semiconductor component and one or more resistive elements are attached to the cooling element. In the method, the cooling element is heated by the one or more resistive elements attached thereto by supplying current from the frequency converter through the one or more resistive elements for obtaining an elevated lowest temperature for the semiconductor component and thereby reducing the amount of temperature change between the highest and the lowest temperatures in the semiconductor component during use of the frequency converter.