The design and implementation of speed control driver which is applied to three-phase brushless DC fan motor are presented in this thesis. In the back-EMF detection circuit, we use digital filter circuits to obtain commutation to overcome the switch noises which are generated by high frequency PWM, without using traditional capacitor filter circuits which need more volume for additional external capacitor. Because the problems of high frequency magnetizing vibration and dispensable power consumption are generated by open-loop fixed frequency PWM speed control approach, closed-loop speed feedback control methods and closed-loop current feedback control methods are adopted to achieve high efficiency and low vibration of the fan motor drivers.

For energy conservation of sensorless two-phase half-wave brushless DC fan, this thesis develops a driver based on analogy circuits with current feedback control and speed feedback control. The main parts of the system include a sensorless start-up circuit, a sensorless commutation detection circuit, a speed feedback control circuit and a current feedback control circuit. Finally, we design experiments to compare it with outside PWM open-loop control and speed feedback control on experiment, the result shows that the driver with both current feedback control and speed feedback control displays better efficiency and lower vibration.

Recently, the government makes good an environment and fully support to semiconductor industries from top to bottom covering the wafer foundry, IC design and equipment testing in Taiwan. Therefore, most of semiconductor brands which are very famous in the international. In early stages, Taiwanese electronic makers which were from OEM (Original Equipment Manufacturing, OEM) model to get resources, technologies and market information. They were became designers and have own R & D via the cooperation of international companies. And also got business form ODM (Original Design Manufacturing, ODM) to its own brand (Own Brand Manufacturing, OBM) direct management about the smile curve at both ends of the market to earn profits. In this study, Taiwan's IC design industry point of view of IC critical success factors of its own brand. In addition, to gathering in DC-FAN motor driving circuits in Taiwan. There are two related information of major leading brands for study. Through "qualitative research" in depth interviews of experts within the industry leader for the interview study, to find out its own brand of IC critical success factors. This research through the collation of expert interviews found that the market should impetus to fully service, increase innovative business models and strengthen integrated development of the semiconductor supply chains to get high techniques for next generation of products. And, to make good relationship with high position of customers that is critical success factors in its own brand. Moreover, it is a base of planning new products for the further. Hope, these findings could offer and give suggestion to industries as a reference. There is a model for reference when some one faces to similar situation.

The design and implementation of speed control driver, which is applied to two-phase brushless DC fan motor is presented in this thesis. In addition, motor coils current limiter, output-stage Snubber circuit, and lock detection and auto-restart circuit are added to the driver for the sake of increasing stability and robustness. Because of high frequency energizing noise and dispensable power consumption problems generated by open-loop fixed frequency PWM speed control approach, several closed-loop speed control methods with speed estimation signal feedback are adopted for improvement. Furthermore, this thesis proposes a sensorless driving control strategy to eliminate Hall sensor in rotor position detection, and similarly has closed-loop speed control methods to achieve the goal of driver cost reduction, size decrease, and good control performance.

This thesis is about the improved design of small size brushless DC fan motor driving circuit. Two main improvements in the new design are increase the stability and decrease the size of motor fan at the same time. To improve the stability, there are two major parts added to the original driving circuit. The delay circuit that protects the H-bridge and the output low current limit circuit. Furthermore, it is believed that the speed control also can improve the stability. With regard to the rotation speed control, two circuits are attached to the motor, 1) speed feedback controller and 2) speed and current feedback controller. Both controllers are attached in the close loop rotation speed control circuit. They are used to increase the efficiency of drive circuit. In order to make the circuit more efficient, they solve problems such as disturbance in miscellaneous noise; also the power dissipation that occurs in open loop rotation speed control circuit. The second improvement in the new design is to reduce the cost and size of system. The design of sensorless control scheme is proposed to replace the Hall sensor to detect rotor position. This sensorless scheme can also supply fan motor voltage to achieve the speed control.