TAILIEUCHUNG - Brushless DC Motor Control Made Easy

This application note discusses the steps of developing several controllers for brushless motors. We cover sensored, sensorless, open loop, and closed loop design. There is even a controller with independent voltage and speed controls so you can discover your motor’s characteristics empirically. | Microchip AN857 Brushless DC Motor Control Made Easy Author Ward Brown Microchip Technology Inc. INTRODUCTION This application note discusses the steps of developing several controllers for brushless motors. We cover sen-sored sensorless open loop and closed loop design. There is even a controller with independent voltage and speed controls so you can discover your motor s characteristics empirically. The code in this application note was developed with the Microchip PIC16F877 PICmicro Microcontroller in conjuction with the In-Circuit Debugger ICD . This combination was chosen because the ICD is inexpensive and code can be debugged in the prototype hardware without need for an extra programmer or emulator. As the design develops we program the tar get device and exercise the code directly from the MPLAB environment. The final code can then be ported to one of the smaller less expensive PICmicro microcontrollers. The porting takes minimal effort because the instruction set is identical for all PICmicro 14-bit core devices. It should also be noted that the code was bench tested and optimized for a Pittman N2311A011 brushless DC motor. Other motors were also tested to assure that the code was generally useful. Anatomy of a BLDC Figure 1 is a simplified illustration of BLDC motor construction. A brushless motor is constructed with a permanent magnet rotor and wire wound stator poles. Electrical energy is converted to mechanical energy by the magnetic attractive forces between the permanent magnet rotor and a rotating magnetic field induced in the wound stator poles. FIGURE 1 SIMPLIFIED BLDC MOTOR DIAGRAMS 2002 Microchip Technology Inc. DS00857A-page 1 AN857 In this example there are three electromagnetic circuits connected at a common point. Each electromagnetic circuit is split in the center thereby permitting the permanent magnet rotor to move in the middle of the induced magnetic field. Most BLDC motors have a three-phase winding topology with star connection. A .

• Cơ khí - Chế tạo máy
• motor diagrams
• sensor versus
• drive timing
• cw sensor
• drive bits
• commutation code segment