What is the working principle of the tower crane?

October 31, 2022

As a kind of crane, the tower crane has a hoisting mechanism, a trolley mechanism and a slewing mechanism.

The special feature of the inverter of the tower cranes is that it is used for the potential load of lifting, the impact and inertia are large, and the starting torque of the frequency converter is very high. The other aspect is to input three-phase electricity, and then the inverter uses IGBT to form DC, and then according to the different gear positions, the speed is different. According to the electric formula of V/f=constant, the voltage is reduced by the duty ratio to realize the variable frequency shifting. f is the frequency, which can be understood as the motor speed. According to the increase of the speed, the output voltage V increases approximately linearly, and different speeds are obtained.

The inverter is just like this: the input power circuit is supplied with power, the output power circuit is connected to the motor, the brake circuit is connected to the brake unit and the braking resistor, and the input control circuit is connected to the speed gear, reset and other control signals. The speed signal has digital quantity and analog. Three ways of quantity and bus, the general lifting will add encoder feedback; the output control circuit is connected to the relay and the indicator light indicates the status of the inverter.

Lifting generally uses a special crane setting software, called Shenghong, set up and the translation mechanism is a little different.

20210609 Topkit Tower Crane