Power Device Current Sampling Circuit With Temperature Compensation
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Solution Overview
Problem
The current output capability of power devices like IGBTs is low due to significant deviations in sampling values output by current sensors at different temperatures, leading to incorrect triggering of overcurrent or short-circuit protection and increased voltage stress.
Innovation Solution
Incorporating a compensation element with an opposite temperature coefficient to the current sampling element to compensate for temperature-induced deviations, ensuring consistent sampling values and reduced trigger thresholds, thereby improving current output capability and reducing voltage stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thresholds for overcurrent protection and short-circuit protection are set to be larger to prevent mistaken triggering at low temperature, then reliability is improved, but current output capability deteriorates
Solution Approach 1:
The patent changes the temperature coefficient parameter of the current sampling element by introducing a compensation element with opposite temperature coefficient characteristics. This compensates for the temperature-dependent drift in sampling values, allowing the use of lower, more appropriate protection thresholds across all temperatures without risking mistaken triggering at low temperatures.
2Reliability
If a larger turn-off resistance or gate capacitance is set to prevent excessive voltage stress during protection triggering, then reliability is improved, but turn-off loss increases
Solution Approach 1:
The patent changes the sampling characteristics by introducing a compensation element, which enables more accurate current measurement across temperature ranges. This accuracy allows for optimized protection triggering that prevents excessive voltage stress without requiring increased turn-off resistance or gate capacitance, thereby avoiding additional turn-off losses.
3Device complexity
If sampling values at different temperatures are allowed to deviate significantly, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent introduces a compensation element as an intermediary component between the current sampling element and the protection circuit. This compensation element acts as a mediator that counteracts temperature-induced variations in sampling values, improving measurement precision without significantly increasing device complexity.
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 ensures consistent sampling values across temperature variations, preventing mistaken protection triggers, reducing turn-off loss, and enhancing the current output capability of power devices.
Implementation Method 1
a temperature coefficient of the current sampling element is opposite to that of the compensation element
Data Source
AI summary
A power device includes a power element, a current sampling element, and a compensation element. The power element includes a first control end, a first electrode, and a second electrode. The current sampling element is configured to detect a current value between the first electrode and the second electrode of the power element. The current sampling element includes a second control end, a third electrode, and a fourth electrode. The second control end is connected to the first control end, the third electrode is connected to the first electrode, and the fourth electrode is connected to the second electrode via the compensation element. The current sampling element is connected in series to the compensation element, and a temperature coefficient of the current sampling element is opposite to that of the compensation element.