| Because of the high operation efficiency and good speed control performance of the traditional DC motor, it plays an important role in industry transmission. However, the traditional DC motor has the disadvantages of limited motor capacity, loud noise and easily generated bark, which are caused by the inherent mechanical commutator and electric brush. For this reason, people have been seeking a new type of motor. With the rapid development of power electronic technology and microcomputer control technology, the brushless DC motor (BLDCM) develops rapidly as well. The BLDCM replaces traditional mechanical commutator by electric commutator, which reserves the merits and avoids the defects of the traditional DC motor. For this reason, the BLDCM has been widely applied in industrial field since its appearance. The BLDCM has the merits of small size, light weight, high efficient, low noise, large capacity and high reliability, which promisingly turn it into the mainstream of motor drive system.Nowadays, the design and study of BLDCM control is popular. The thesis studied the control system of the BLDCM combined with DSP. The work of this thesis includes the following aspects:Firstly, the structure, operation principle, half-bridge chopper control and mathematical model of motor were analyzed. As for the control object that is the 2.2KW BLDCM with trapezoidal waveform of back electromotive-force (EMF), appropriate control plan was selected.Secondly, the hardware circuit including power supply circuit, power invertion circuit, current detection circuit, voltage detection circuit, position detection circuit, current chopper circuit, driving circuit, DSP peripheral circuit and display circuit etc were designed.Thirdly, the control strategy of BLDCM which provides a basis for the software design including commutation program, current and voltage sampling program, PWM duty ratio reload program, speed calculation program, serial display program, speed and current double-loop regulation program and keyboard program etc were studied. Finally, through by experiments, the hardware feasibility was tested, the software design was modified according to control requirement, and the control performance was improved.The experiment result showed that the BLDCM has an excellent dynamic and static performance as well as splendid protection element which improved the operation reliability. |
