Research On AC Drive System For Electric Locomotive Used In Coal Mine

At present, AC driver is widely used by electric locomotive in coal mine abroad, however it is rarely applied by the electric locomotive in domestic coal mine. A control strategy of AC drive system applied to electric locomotive in coal mine is presented in consideration of particular condition that variational range of DC supply power voltage is larger in coal mine and specific problems existed in application of AC drive system to coal mine electric locomotive. V/F control, open-loop control of speed, closed-loop control of the inverter output-voltage and current cut-off negative feedback are adopted in the strategy. An emulation model of the system based on MATLAB/Simulink is realized. The emulation results verifys that the strategy can adapt to above particular condition and solve above specific problems. Based on TMS320LF2407A DSP, a scheme of implementing AC drive system used in 10 ton coal mine electric locomotive is presented. The main circuit, drive circuit, control circuit and protection circuit of the system are designed. A test platform of electric locomotive is set up and corresponding software is developed. The DSP controller, TMS320LF2407A, suitable for motor control is used in the scheme. It has many merits such as low-cost, low-power, high-performance processing. The peripheral equipments for motor control are integrated inside. Apparently, the hardware circuit of the system is simplified and the cost is lowered. The experimental results indicate that according to proposed design principle of AC drive system, the test prototype of coal mine electric locomotive is stable and reliable. To specific condition of coal mine power supply, closed-loop control of inverter output voltage has to be used. Motor and inverter can be protected by the current cut-off negative feedback when motor is overload or locked-rotor. The control arithmetic of V/F is simple and easy to realize. When speed is low, the torque of motor is small. The torque can be increased by compensation of I*R during lower frequency, consequently, compensated torque can satisfy the need of electric locomotive.