| The line-supplied locomotive is the primary vehicle in the coal mine. To some extent it's reliability and energy-saving is very important to the efficiency of digging minerals. At present, DC adjustable-speed drive is still used in those cases. But because DC motor has many disadvantages, such as high-cost, low-reliability, easy-damage of commutator, long-periods of maintenance and low-efficiency, with the fast development of the mineral project, DC drive system with low-performances can't meet the needs of the development of corporation. So it is absolutely necessarily to replace DC drive with AC drive.According to the operation context and traction property of the line-supplied mining locomotive, a digital signal processor(DSP) based variable voltage variable frequency (VVVF) drive system is presented, in which the U/f control technology and space vector modulation (SVM) method are employed. The principle of speed-adjustable AC drive is firstly discussed. An optimized bus clamped SVM (BCSVM) method is obtained based on the conventional seven-segment SVM. The difference between SPWM and SVM method is described in detail. The influence of dead-time effect on performance of the output voltages is analyzed. An effective approach to accurately compensate the dead-time effect is presented. On the aspect of hardware, the control circuits, inverter circuits and protection circuits of the speed-adjustable system are designed, which takes the TMS320F2812 as kernel. On the aspect of software, the program of system is implemented using 32-bits fixed-point C language. In order to overcome the problem caused by the fluctuating of the DC supply in the mine, the simulation of the speed-adjustable AC drive is designed based on MATLAB/SIMULINK. The results of the simulation and experiments show that the presented VVVF Speed-variable drive system has good performances and traction properties which is quiet applicable to the line-supplied locomotives.
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