What are the advantages of AC speed regulating electric locomotive compared with DC speed regulating electric locomotive?

1. Compared with DC motor, AC motor has the characteristics of simple structure, small volume, light weight, strong overload capacity and high efficiency; The maintenance cost of DC motor is much higher than that of three-phase asynchronous motor due to the coil on the rotor and the easily worn commutating copper ring and carbon brush;

2. As DC speed regulation is operated with resistors, the power consumption is large. As AC variable frequency speed regulation does not use high energy consuming resistors, the power saving rate can reach 35%. If the electric locomotive is set with regenerative feed braking, the electric energy generated by the motor can be fed back to the battery when the electric locomotive decelerates or goes downhill, which can greatly save electric energy and extend the charging time.

3. The DC drive of the electric locomotive is graded. When driving at a low speed, the driver needs to constantly switch between gear 1 and gear 0 to obtain a slow speed. The AC variable frequency speed regulation is stepless and uniform. The speed and parking are completely controlled by the speed regulating handle, and the driver is allowed to suddenly accelerate to the maximum speed when starting at zero speed, because the frequency rise time of frequency conversion speed regulation can be set by the software.

4. The traction force of AC drive electric locomotive is larger than that of DC drive electric locomotive. The traction force of 7t DC drive electric locomotive is only 13.8KN, while the traction force of 7t AC drive electric locomotive can reach 20KN, which can reach or exceed the traction force of 10t DC drive electric locomotive. As the speed of variable frequency speed regulation increases slowly, the impact between gears is avoided and the service life of gears is extended; When decelerating, it is controlled by the speed regulating handle, and the brake pads do not need to hold the wheels to decelerate, thus reducing the wear of the brake pads.

The mining electric locomotive works in the harsh environment underground. The speed control system is in the state of frequent starting, braking, acceleration and deceleration. It also needs to adapt to the load going up and down the slope and bumpy road conditions. Therefore, the starting torque of the motor is required to be large and the overload capacity is strong. The AC speed regulating system with direct torque control can make the three-phase asynchronous motor reach or exceed the starting torque and traction characteristics of the DC motor, and enhance the starting capacity of the electric locomotive with load.