"24V DC Cooling Fan" variable speed control, low noise, reliability, long life, low power consumption, protection, maintenance / upgrade ease of communication interface and features are based on the characteristics of flash MCU based BLDC. It describes a variable speed BLDC fan control algorithm including a method to reduce noise, power consumption consideration, lock detection and automatic restart, thermal shunt and communication interfaces. DC fan and BLDC fan distinction BLDC fan and fan of the traditional physical appearance is basically no difference. Principles of the two fans in converting electrical energy into mechanical motion used when the same. When the DC voltage is applied to its terminal, the fan rotation speed of the fan depends on the voltage applied to the terminal. The main difference is that their internal structure. Both fan systems require the commutation, a current flows through the fan windings to reverse once in each rotation of 180 degrees.