一种基于斜率控制的功率模块过温保护策略

An Over-temperature Protection Strategy Based on the Slope Control of the Power Module

传统功率模块的过温保护通常采用外置NTC热敏电阻的方式进行,当检测到温度高于过温保护点时,认为绝缘栅双极型晶体管(IGBT)温度过高,封锁脉宽调制(PWM)输出。该过温保护方式在实际应用中存在两个问题:过温保护点无法根据散热条件自动调整,风机不运行或风道阻塞时可能无法有效保护功率模块。这两个问题严重影响产品的可靠性,如果不能有效解决,产品本身将会存在安全隐患。针对此问题,提出了一种新的保护策略,通过计算温度曲线斜率,判断风机是否正常运行,同时对过温保护点进行调整,通过实验验证,该保护策略效果良好,提高了产品可靠性。

The traditional over-temperature protection of power module usually through an external negative tempera- ture coefficient （NTC） thermistor.When the detected temperature is higher than the over-temperature protection, we think the insulated gate bipolar transistor （IGBT） temperature is too high,then block the pulse width modulation （PWM）.The over-temperature protection has two problems in the practical application：over-temperature protection point cannot be automatically adjusted according to the thermal conditions, and the power module cannot be effective- ly protected when the fan is not running or the radiator is blocked.The two problems seriously affect the reliability of the product.If the problems cannot be effectively solved,the product itself has safety problems.Aiming at this prob- lem, this article provides a new protection strategy, which through calculating the temperature curve slope ,judging whether the fan is working normal,meanwhile,adjusting the over-temperature protection point.Through experimental verification, the protection strategy has good effect, which can improve the reliability of the product.