Tower crane hoisting and speed control system and speed control method thereof

The invention discloses a tower crane hoisting and speed control system which comprises a PLC (Programmable Logic Controller); the PLC is respectively connected with an operation handle, a frequency converter and a hoisting sensor simultaneously; the frequency converter is connected with a motor and a speed measurement encoder to form a closed loop; the motor is connected with a winding drum through a reduction gearbox; and the hoisting sensor is used for detecting the hoisting weight through detecting the tensile force of a steel rope. The invention also discloses a tower crane hoisting and speed regulation control method; the PLC is adopted for controlling the speed regulation of the frequency converter to realize the gear separation and stepless speed regulation combination; during the working process, the PLC obtains a handle signal and a hoisting signal in real time and also obtains the current of the motor through a 485 bus; and a hoisting speed control mode is determined according to the state of the system. The device and the method have the beneficial effects that the practical running speed of the tower crane is regulated under the maximum speed limit of all gears, the unpredictability of a driver for speed is avoided, the PLC is adopted for realizing the closed-loop control of the current, and the speed stability is ensured.