Multi-stage rotation speed control device for fan motor

The utility model discloses a multi-stage rotation speed control device for a fan motor, which comprises a drive element, a motor rotation speed sensing element, a resistance circuit, a divider resistor and a multi-stage switch, wherein the controlled terminal of the drive element is connected with the multi-stage switch, the output terminal of the drive element is connected with a fan motor, the detection terminal of the drive element is connected with the motor rotation speed sensing element; the resistance circuit comprises a plurality of resistance elements with different resistance values; the multi-stage switch is connected with the resistance circuit, the divider resistor, the controlled terminal of the drive element and a voltage source, wherein the multi-stage switch can selectively switch on any resistance element to the voltage source and establish an input voltage on any resistance element by dividing voltage. The drive element can drive the fan motor to rotate at specific corresponding speed acco