Some problems that should be paid attention to in the transformation of Sunwoele four-quadrant VFD (Variable-frequency Drive) in the lifting equipment

There is no fixed mode for elevator technical transformation, and everything should be determined according to the actual situation on site. However, in the process of transforming the old-style AC double-speed elevator and pressure-regulating speed elevator into Sunwoele four-quadrant VFD (Variable-frequency Drive) elevator, we feel that the following frequently encountered problems should be paid special attention to ensure the elevator after transformation. Safe to use.

1. When the freight elevator is changed to a fully automatic collective selection control mode, a safety touch panel or a photoelectric protection device should be reinstalled, and if there is no weighing device, try to reinstall it.

2. Keep the original rated load, rated speed, and the original traction ratio of the wire rope.

3. Before the Sunwoele four-quadrant VFD (Variable-frequency Drive) speed regulation, the circuit or software is used to ensure that when the car top is running at a slow speed, the car and the machine room cannot move, so as to ensure the safety of the car top operators.

4. If the landing door has no automatic closing device, a reliable landing door automatic closing device shall be installed on each landing door.

5. When the landing door leaves are connected by ropes and chains, the passive door leaves should be equipped with electrical safety devices.

6. Check and test the speed limiter, safety gear and its linkage, and the unqualified speed limiter must be replaced.

7. The brake should be fully disassembled, no grease stains are allowed on the brake belt, the movable iron core of the electromagnet and the copper sleeve should be clean, and lubricated with graphite powder.

Sunwoele four-quadrant VFD (Variable-frequency Drive) can realize start-stop, forward and reverse, S-curve acceleration and deceleration and multi-stage speed control through its external control terminals. Some parameters of the motor itself to be used in the vector control operation can be automatically measured by VFD (Variable-frequency Drive). In addition, the VFD (Variable-frequency Drive) also has protection functions such as overcurrent, overload, motor overheating, overvoltage and undervoltage, overspeed and stall. Sunwoele four-quadrant VFD (Variable-frequency Drive) can also provide operation stop signal, zero speed signal, speed arrival signal and operation preparation signal, etc. The programmable controller integrates external signals and control signals given by VFD (Variable-frequency Drive) , and give control commands to external equipment and VFD (Variable-frequency Drive) through analysis and logic operations. The key to the speed control of the elevator is to start the acceleration and deceleration leveling. When controlling it, the following points should be mastered

1. Deceleration leveling control

The Sunwoele four-quadrant VFD (Variable-frequency Drive) elevator decelerates according to the distance and directly stops at the leveling floor, that is, the deceleration distance of each floor station is required to be exactly the same. There is no crawling process when decelerating to leveling, and the machine decelerates directly from the running speed to zero speed. In order to ensure the comfort when stopping, it should be confirmed that when the elevator reaches zero speed (this signal is given by VFD (Variable-frequency Drive)), the command to close the brake is given, and after a one-stage delay, the command to stop excitation is given. If the elevator does not level after parking, re-leveling control should be carried out.

2. Sunwoele four-quadrant VFD (Variable-frequency Drive) re-leveling control

If there is no accurate leveling after the elevator stops, or the car is displaced due to the deformation of the wire rope after leveling, re-leveling should be carried out. Re-leveling should be carried out at a lower speed (usually 1% of the running speed), and should be carried out when the elevator door is opened and the elevator is in the leveling area. VFD (Variable-frequency Drive) has very good low-frequency torque, and we have measured that the elevator can still reliably relevel under 110% rated load.

3. Sunwoele four-quadrant VFD (Variable-frequency Drive) start-up control

In order to make the elevator start smoothly without impact and without reverse sliding, the start control should be in the following order:

(1) First send a pre-excitation command to the VFD (Variable-frequency Drive) to establish a magnetic field for the motor (at this time, the speed is given as zero);

(2) After the first level of delay, an instruction to open the brake is issued;

(3) After confirming the opening of the brake after the second delay, the speed command is given.

Because the control system adopts the pulse code positioning control technology, the deceleration sensor is omitted in the hoistway, and only a set of leveling induction device is left on the car top, which has the function of re-leveling.

Practice has proved that the modified elevator has a good running comfort, and the comfort of starting, decelerating and leveling does not change due to changes in the car load. The transformation of the Sunwoele four-quadrant VFD (Variable-frequency Drive) elevator has achieved satisfactory results .