Application of Sunwoele VFD (Variable-frequency Drive) in the lifting mechanism of Taizhou Port 40T gantry crane

This year, Taizhou Port used PLC and Sunwoele VFD (Variable-frequency Drive) to electrically upgrade a second-hand 40T-30M multi-purpose door operator. The lifting mechanical part of the machine is configured with 2 sets of identical independent mechanisms (2 motors, double drums, 4 ropes) that can perform hook and grab operations. The electrical control part is an ordinary relay circuit, and the electrical drive is a winding motor. After modification, a variable frequency motor is used and driven by a VFD (Variable-frequency Drive).

Now we will introduce the selection principles, debugging application process and usage of VFD (Variable-frequency Drive) in the lifting mechanism of the door operator:

1. VFD (Variable-frequency Drive) selection principles

①With vector control technology

This is because the lifting load of the door operator has a large starting torque (70%-150% of the rated torque is required), but the starting current cannot be too large (1.2-1.5 times the rated current). The V/F control method of ordinary VFD (Variable-frequency Drive) cannot be realized. The result is that the motor cannot start and causes stalling, or the starting current is too large and causes over-current protection. VFD (Variable-frequency Drive) with vector control technology can do this.

In layman's terms, vector control imitates the control method of a DC motor, decomposing the stator current vector of an asynchronous motor into a current component that generates a magnetic field (excitation current) and a current component that generates torque (torque current), which are controlled separately to make the asynchronous motor The motor not only matches the DC motor in the speed range, but also can control the torque generated by the asynchronous motor to achieve smooth operation at extremely low speeds and high-torque and high-precision speed control.

②With torque following technology

This technology uses one VFD (Variable-frequency Drive) as the main drive, using speed control mode, and another VFD (Variable-frequency Drive) as the auxiliary drive, using torque control mode. Use the torque output of the main drive as the torque reference of the auxiliary drive, so that the given signal of the auxiliary drive is torque rather than frequency. The auxiliary drive follows the changes in the main drive torque and achieves the purpose of even load distribution control. This control method has high control accuracy and fast dynamic response. When the load torque of the auxiliary drive is large, the motor speed is low; when the load torque is small, the motor speed is high; the maximum frequency can be reached when no load is present.

③Has precise brake logic sequence control and monitoring

The lifting mechanism of the door operator is controlled by VFD (Variable-frequency Drive). The start and stop of the motor must be accurately coordinated with the opening and closing of the brake to avoid the "slipping hook" phenomenon.

④The product has sophisticated workmanship, high reliability, and the manufacturer’s service is considerate and timely.

⑤The product has a lower price

two. Debugging and application process

In view of the above requirements, we selected two HSF600-315RG/350RP-T4 VFDs (Variable-frequency Drives) from Sunwoele Company for the lifting mechanism. During the debugging and application process, several major technical advantages of the VFD (Variable-frequency Drive) were highlighted:

1. Real current vector control, we use its PG vector control mode, the speed control accuracy reaches ±0.02%, the starting torque, zero speed can reach 150% of the rated torque, the output torque is large, the current is small, and the operation is stable. When lifting heavy objects, the gantry crane can stop smoothly in the air and start again with free control.

2. Exquisite torque control and torque following technology, which is especially reflected in the door crane grab operation. Our specific application method is: when the door operator is working with the grab bucket, the opening and closing rope is lifted to close the grab bucket. At this time, the support rope is transferred to the torque control mode. After debugging, the support rope is given a 1% rated torque given value. A motor speed limit setting of -10% is more appropriate. (At this time, the torque direction of the support rope motor is opposite to the speed direction, which is the so-called uncoiler action state), so that the support rope can follow the grab and descend without slackening, and at the same time, the purpose of digging deeply with the grab can be achieved. When the grab bucket is completely closed and the opening and closing ropes are lifted together with the support rope, the torque given value of the support rope is changed from 1% of the rated value to the output torque value of the opening and closing rope (this is a dynamic process setting that is constantly decreasing. value), the given value of the speed limit is changed from -10% of the rated value to 120% of the maximum speed value of the opening and closing rope. At this time, the support rope enters the torque following action state. (At this time, the torque direction of the support rope motor is the same as the speed direction, which is the so-called rewinder operating state) Initially, the support rope is in an unloaded state and runs at a speed exceeding the opening and closing rope (the so-called chasing rope). After alignment, the torque is distributed. When the support rope torque is close to the opening and closing rope torque, it switches to the speed control mode and enters the next grabbing cycle.

This technology has been used very successfully. The driver can operate it easily and improve the efficiency of the grab operation. (In addition, the torque control function of the HSF600 series VFD (Variable-frequency Drive) is used for crane cable drums such as gantry cranes and quay cranes. It can achieve convenient and fast application and precise control. It is the best solution for existing hysteresis cables and other types of cables. Upgraded products for roll products.)

3. Brake control is another key to the success or failure of VFD (Variable-frequency Drive) used in hoisting mechanisms. Sunwoele VFD (Variable-frequency Drive) has as many as 37 multi-function output settings. For example, the zero speed output accurately controls the opening and closing of the brake. We observed that during the long-term heavy operation of nearly 40T grab, the brake wheel had no temperature at all. However, to ensure safety