Brushless DC (direct current) motor air conditioning system control circuit

The invention discloses a brushless DC (direct current) motor air conditioning system control circuit comprising a microcontroller U4, an indoor DC fan motor rotational speed control circuit, an outdoor DC fan rotational motor rotational speed control circuit, an outdoor DC motor fixed rotational speed and adjustable rotational speed switching circuit, an indoor motor speed regulation voltage shutdown circuit, an outdoor motor speed regulation voltage shutdown circuit and a temperature detection circuit, wherein the outdoor DC fan motor rotational speed control circuit comprises a first circuit unit and a second circuit unit; the circuit board of the brushless DC (direct current) motor air conditioning system control circuit consists of an outdoor control panel and an indoor control panel; and the outdoor control panel and the indoor control panel are connected through plug connectors CN2 and CN4. The brushless DC (direct current) motor air conditioning system control circuit can perform speed regulation control on the indoor and outdoor fan motors at random to achieve a good heating effect, and match the outdoor motor fixed rotational speed control and closed loop speed regulation control at random so as to improve the development convenience of products.