DC-DC Converter Diode Overheat Protection via Calculated Temperature
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Solution Overview
Problem
Existing DC-DC voltage conversion devices do not adequately address the overheating protection of diode elements, which can exceed the temperature of power semiconductor elements, particularly under specific usage conditions, leading to potential destruction.
Innovation Solution
A DC-DC voltage conversion device that calculates the diode element temperature using a correction calculation based on the detected temperature of the power semiconductor element and the step-up ratio, incorporating a temperature detection unit and overheat protection mechanism to prevent diode element overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensor is installed to directly measure junction temperature of power semiconductor element, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses the case temperature as an intermediary measurement point. Instead of directly measuring the difficult-to-access junction temperature, a temperature sensor measures the case temperature, and the junction temperature is estimated by adding a temperature difference value derived from power loss calculations. This intermediary approach enables accurate temperature monitoring without direct junction access.
Solution Approach 2:
The patent replaces direct physical temperature measurement at the junction with an indirect calculation method. By substituting the mechanical/physical measurement approach with a computational approach (measuring case temperature and calculating junction temperature through power loss analysis), the system achieves measurement precision without the complexity of direct junction sensing.
2Ease of manufacture
If temperature sensor is installed at predetermined position in power semiconductor module, then ease of manufacture is improved, but measurement precision deteriorates
Solution Approach 1:
The case temperature serves as an intermediary that bridges the gap between easy-to-measure positions and the actual junction temperature. The temperature sensor is conveniently installed at the case, and through calculation involving power loss and thermal resistance, the junction temperature is accurately reconstructed despite the indirect measurement location.
Solution Approach 2:
The patent transforms the temperature measurement problem by changing from direct junction temperature measurement to case temperature measurement plus calculated temperature rise. This parameter transformation allows easy sensor installation while maintaining measurement accuracy through the relationship: Tjunc = Tcase + (Ploss × Rth).
3Reliability
If overheat protection function is implemented using calculated junction temperature, then reliability is improved, but device complexity increases
Solution Approach 1:
The case temperature acts as an intermediary for protection control. The temperature sensor monitors case temperature, and the control unit uses this intermediate measurement along with power loss data to determine junction temperature and trigger protective actions, simplifying the protection system compared to direct junction sensing.
Solution Approach 2:
The patent replaces complex direct junction temperature monitoring with a simpler computational approach. By substituting physical junction access with electrical measurements and calculations based on power loss and thermal resistance, the protection function is achieved with reduced system complexity.
4Measurement precision
If diode element temperature is directly measured with temperature sensor, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a thermal model copy of the diode element temperature based on the power semiconductor element temperature measurement. By measuring the power semiconductor element temperature and using the known thermal relationship (including the step-up ratio effect), the diode element temperature is calculated without requiring a separate physical sensor on the diode.
Solution Approach 2:
The temperature sensor and measurement system serve multiple functions: directly measuring power semiconductor element temperature and indirectly determining diode element temperature through calculation. This multi-functionality eliminates the need for separate measurement systems for different components.
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
Effectively protects diode elements from overheating by accurately estimating their temperature and implementing protective measures, ensuring reliable operation at a low cost and with a simple configuration.
Implementation Method 1
the heat is transferred from the junction of the power semiconductor element to a case or heat sink of the semiconductor element, and dissipated
Data Source
AI summary
In a DC-DC voltage conversion device, overheat of a diode element connected in anti-parallel with a semiconductor switching element is a problem, and in order to resolve this, a temperature of a semiconductor switching element of a main conversion circuit is detected, a temperature of a diode element connected in parallel with the semiconductor switching element is calculated using a correction calculation of the detected semiconductor switching element temperature value in accordance with a step-up ratio of the DC-DC voltage conversion device, and diode element overheat protection is carried out in accordance with the calculated temperature value.