Abstract
Compared with rotary motors, linear motors possess many advantages in linear motion driving applications. In this thesis, the development of a high-performance linear brushless DC motor (LBDCM) drive and its quantitative direct digital control are studied. First, an one-dimensional table driven by LBDCM is established, wherein the Hall-effect sensors and linear encoder are employed to obtain the position information of moving member. For obtaining good position driving performance, a current-controlled voltage source inverter (VSI) with lowly-distorted sinusoidal output current is developed, the commutation instant tuning of inverter to yield better force generating capability of a LBDCM is also studied. A PC-based and a DSP-based digital control environments are constructed for implementing the control algorithms developed in this thesis.The dynamic model is indispensable for performing the controller analysis and design. In this thesis, the dynamic model of LBDCM is estimated from the measurements. In performing the direct digital control, some practical issues for achieving satisfactory control performance are first studied. Then, in order to have the desired tracking and regulation control performances simultaneously, a two-degrees-of-freedom (2DOF) position controller and two quantitative design approaches are developed for finding the controller parameters systematically. The first design approach is easy to derive, but it is easier to result in oscillatory control force. The modification to solve this problem is proposed. As to the second design approach, rather than performing the direct operation of transfer functions, the governing equations relating the control specifications, the parameters of dynamic model and 2DOF controller are derived. The effectiveness of the proposed controllers and the performance of the resulted drive system are confirmed by some simulation and measured results.