At present, current detection resistance is an essential component in automotive electronic control and transmission system. For reasons of cost and miniaturization, the surface mount high precision sampling resistors is increasingly applied, which requires a milliohm level.
Because the circuit board of electric vehicle adopts a highly integrated design scheme, precision resistance will produce a lot of heat when it detects current. The temperature of electric vehicle will rise to 90 ℃ to 100 ℃ during drive. The local temperature of electric vehicles will reach 125 ℃ or higher. The increase in ambient temperature, together with the heat generated by the precision resistor, will cause the precision resistor to have a temperature difference of more than 100 degrees. At such a high temperature, the precision resistor would easily burn down without the characteristic of low temperature drift or unable to work.
On the other hand, high precision resistor is used in battery management system of electric vehicle. This kind of high precision resistor is adopted because of the characteristics of high precision and low temperature drift. Through hole types meet this features most, surface mount types are relatively few. These two types of precision resistors are used in many advanced battery management systems in the world, and with the improvement of resistance technology, the performance of these resistors will become stronger and stronger.
There are many types of low-temperature drift resistors on the market. These resistors drift around the 20~150PPM, and the more precise resistors can drift up to 1 PPM, 5PMM. When the test temperature changes greatly and the accuracy is greater than 1%, the test deviation of 100A is more than 1A. This type of resistor is not suitable for use in electric vehicles. The precision of resistance in battery management system is less than 1. If the tolerance can be 0.5% or even 0.1%, it is more suitable for the ideal design of electric vehicle.
