Motor rotating speed detection device, detection method, motor system and air conditioner

The invention provides a motor rotating speed detection device, a motor rotating speed detection method, a motor system and an air conditioner. The motor rotating speed detection device comprises a voltage detection circuit connected with a motor and configured to detect any two line voltages of the motor and superpose the any two line voltages to obtain a first voltage; a voltage conversion circuit connected with the voltage detection circuit and configured to convert the first voltage into a second voltage; a processing assembly connected with the voltage conversion circuit and configured toobtain the rotating speed according to the second voltage. Through the technical scheme of the invention, the cost increase caused by using an encoder to measure the voltage, can be avoided, and therotation speed detection failure caused by the disconnection of a certain phase, can be avoided. 本发明提出了一种电机转速检测装置、电机转速检测方法、电机系统及空调器。其中，电机转速检测装置包括：电压检测电路，与电机相连接，电压检测电路被配置为检测电机的任意两个线电压，并将任意两个线电压进行叠加，获取第一电压；电压转换电路，与电压检测电路相连接，电压转换