89019101 Blower Motor Resistor

Automobile blower resistance principle:
1. The speed regulation of the blower in the new automobile air conditioner mostly adopts the speed regulation module, which controls the power output change of the power tube (transistor) through PWM to adjust the fan speed;
2. Especially in the automatic air conditioning system, the air conditioning control unit (including the DSP chip) is generally used. When the air conditioner is working, the DSP sends instructions to adjust the duty cycle of the PWM (pulse width modulator) according to the program settings and the feedback signal in the car. After the optocoupler isolation conversion, the power field effect transistor (MOSFET) is used as the main switching element, and the output voltage is changed by changing the conduction mode and on-off ratio of the switching element, thereby adjusting the fan speed. The main gd1 and gd2 of the circuit are isolated and amplified drive components, which can be isolated by optoelectronic coupling or transformer;
3. vt1 and vt2 are the main switching elements (represented by mosfet in Figure 1), vd1 and vd2 are two freewheeling diodes, and la is a filter inductor.