Design of control scheme for battery operated material transfer trolley
2019-06-04
Design of control scheme for battery operated material transfer trolley
As a factory production and transportation vehicle, the battery operated material transfer trolley generally has the following three types of power supply modes: (1) Power supply from the trolley line. (2) cable reel power supply. (3) Low-voltage rail power supply. However, if the transportation distance is long or needs to be transported all day, the above three power supply methods have their shortcomings. The battery traction electric flat car does not need to connect the cable, so it can easily cross the bridge (through the door hanging stacking site), without destroying the integrity of the road surface, without considering the cable being crushed; because the power is in the car, it can be used in the open air. With the advancement of battery technology, its working life is increasing, prices are falling, and applications are widespread.
Battery operated material transfer trolley
Taking the 100 ton battery operated material transfer trolley as an example, in order to ensure a large starting torque and a strong overload capability, the traction motor selects a series-excited DC motor DC 75V10kw, and the configured power supply is a traction battery (VCDH580, 2V. A total of 40 pieces). Place it on the bottom of the electric flat car and protect it accordingly. The Cortis DC governor manufactured by American General Motors is used to adjust the speed of the battery traction electric flat car, and is provided with overvoltage and undervoltage protection when the voltage is too low. The governor makes the vehicle decelerate and at the same time prompts the driver to charge in time through the voltmeter, avoiding overdischarge of the battery and prolonging the service life of the battery.
1, Curtis DC speed regulator
The Cortis DC governor was developed at the end of the 20th century. It makes the control of the electric flat car more convenient and reliable, and has a good application prospect in small and medium-sized electric flat cars. The governor generally needs to be assembled into an electronic control system with other auxiliary hardware such as the main contactor, and together with the accelerator, the motor speed is controlled.
2, start
The starting of the DC motor refers to the process of accelerating from a stationary state to a stable operating state after the motor is powered on. At the moment of starting, the starting torque and starting current are respectively: dynamic engineering design work. Since the starting speed is o, the armature electromotive force is 0, and the armature resistance is small, so the starting current value is large, so the DC motor is generally not allowed to start directly. The Curtis DC governor starts smoothly at a set minimum current.
Battery traction electric material transfer trolleys use a handheld operator for starting operations. The control switch on the hand-held operator is used to turn on the control power, and the direction selector switch is used to select the direction of travel of the tractor. Rotate the speed control handle on the hand-held operator clockwise, the main contactor is energized and closed, the motor starts to rotate, the rotation increases, the motor speed increases; the speed control knob rotates counterclockwise, the motor speed decreases, and the main contact is rotated to the end point. The power is released and the motor stops rotating. The battery powered transfer trolleys stop.
3, brake
Accurate parking of battery traction transfer trolleys is also an important aspect of control. Here we use the combination of the governor and the electromagnetic brake, the application effect is obvious. Through the brake function of the governor itself and the action of the electromagnetic brake holding brake, the electric flat trolley has a short braking distance, which fully meets the requirements of the station. In order to save battery power, the electromagnetic brake is made of energy-saving system (the operating current is 3A and the holding current is o.02A). The electromagnetic brake "brake start" and the contactor "brake hold" contactor act while the motor is rotating, causing the brake mechanism to open. When the action is 2s, the "brake start" contactor is released and the "brake hold" contactor continues to attract, allowing the electromagnetic brake to continue to operate with a small current.
4, charging
Use a smart charger to charge the battery. When charging, the charger can intelligently control the battery current and charging time (to achieve 3-stage charging, ie constant current-constant voltage-constant current automatic conversion), to avoid charging and discharging of the battery under high current conditions, and battery plate The deformation, vulcanization, and active material falling off delays the battery life. After a preliminary understanding of battery performance (manufacturer's test), its service life is estimated as follows:
(1) When the battery is recharged after 100% deep discharge, it can be recycled 100 to 200 times.
(2) When the battery is recharged after 70% deep discharge, it can be recycled 300 to 600 times.
(3) When the battery is recharged after 50% deep discharge, it can be recycled for 500 to 1000 times.
(4) When the battery is recharged after 30% deep discharge, it can be recycled 1000 to 2000 times.
Battery operated transfer trolley powered by battery and DC motor is not restricted by route and environment. It has low requirements on track. Compared with electric flat car requiring high voltage power supply, it has advantages in long distance and open air operation. Moreover, the design idea is more advanced, the control is reliable, the positioning is accurate, and the design of the battery operated material transfer trolley and the design of the battery electric flat car are provided for reference, which adds a new content for the development of the battery transfer trolleys.
Therefore, do not wait until the battery is completely discharged before recharging. Generally, the battery can be recharged and discharged for more than 1 ooo times as long as it meets the above conditions (3) or (4), and its service life can be more than 3 years.
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