By the method of frequency measurement,instant rotational speed is measured in the test system,angular acceleration is calculated by using the feature of the MCU with the least square method.

• 介绍了一种发动机无外载功率检测系统的软、硬件设计,利用测频法测量出某一时刻的瞬时速度,并利用最小二乘法求出角加速度。