IPM Temperature Detection Circuit With PWM Calibration
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Solution Overview
Problem
Conventional temperature detection circuits in Intelligent Power Modules (IPMs) suffer from poor accuracy due to characteristic variations in electronic components and temperature sensors, leading to inconsistent temperature detection across multiple IPMs.
Innovation Solution
A temperature detection circuit that includes a signal generation circuit and a correction circuit, which sets a correction value to accurately indicate the temperature of a switching element by adjusting the signal output during a reference temperature setting mode, thereby correcting for component variations and enhancing detection precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature detection circuit is used, then device complexity is reduced, but temperature detection accuracy deteriorates due to characteristic variations in electronic components and temperature sensor
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values in a correction value storage unit before actual temperature detection. During manufacturing or initialization, the system performs calibration to determine correction values that compensate for component variations, storing these in advance. When temperature detection is needed, the pre-stored correction values are directly applied without requiring complex real-time calculations, thus improving accuracy while maintaining simple runtime circuitry.
Solution Approach 2:
The patent introduces a correction value storage unit and correction circuit as intermediary elements between the temperature sensor and the output. These intermediaries process the raw temperature signal by applying correction values that compensate for component variations. The correction circuit acts as a mediator that adjusts the detection signal using stored correction data, thereby improving measurement precision without significantly increasing overall system complexity.
2Measurement precision
If correction circuit is added to compensate for characteristic variations, then temperature detection accuracy is improved, but device complexity increases
Solution Approach 1:
The correction values are calculated and stored in advance during manufacturing or system initialization, rather than computing them in real-time during temperature detection. This preliminary calculation phase allows complex compensation algorithms to be executed once, with the results stored for rapid retrieval during operation, thereby improving accuracy without adding complex real-time computation hardware.
Solution Approach 2:
The system performs self-calibration by automatically determining correction values based on its own component characteristics during initialization. The correction circuit uses the temperature sensor and electronic components themselves to generate the correction data needed, eliminating the need for external calibration equipment or manual adjustment, thus improving accuracy while keeping the added complexity minimal.
3Measurement precision
If temperature sensor with high precision is used, then temperature detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the parameter being corrected from the physical characteristics of the temperature sensor to the electrical signal processing parameters. Instead of requiring a high-precision temperature sensor, the system uses a standard sensor and compensates for its variations by adjusting the electrical signal through correction values. This transforms the problem from a hardware precision issue to a software/signal processing solution, maintaining accuracy while reducing manufacturing costs.
Solution Approach 2:
The patent converts the harmful effect of component variations and characteristic deviations into a beneficial correction mechanism. By measuring the actual variations in electronic components and temperature sensors, the system generates specific correction values that compensate for these variations. What would normally be considered defects or sources of error are transformed into useful information for improving accuracy, allowing standard components to achieve precision levels previously requiring expensive specialized parts.
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
The solution enables high-accuracy temperature detection of switching elements by compensating for characteristic variations, effectively preventing thermal failures and ensuring reliable operation of IPMs.
Implementation Method 1
a temperature sensor having a resistance varying in accordance with a temperature of a switching element
Data Source
AI summary
A PWM signal generation circuit in an IPM includes an amplification circuit amplifying a voltage across terminals of a temperature sensor, a comparison circuit generating a PWM signal based on a triangular wave signal and an output signal of the amplification circuit, and a correction circuit setting an amplification ratio of the amplification circuit such that a pulse width of the PWM signal is set to a reference pulse width in an adjustment mode in which a switching element is caused to have a reference temperature. Consequently, characteristic variations in the temperature sensor, the amplification circuit, and the like can be corrected, and the temperature of the switching element can be detected with high accuracy.