| As the rapid development of elevator drag and control technique, the elevator has been developed from the DC motor drive to the AC single speed and AC double speed motor drive, and then to the AC variable voltage (ACVV) control. Now it is running to the variable voltage variable frequency (VWF) control, and this development leads to the infinite progress of the elevator's reliability, security, comfort, floor precision, lifting speed, power saving and noise preventing.Newly produced elevators all have adopted the VWF that varies motors speed linearly. Because the VWF elevator controlled by computer has the perfect self-inspection, self-diagnosis, and self-protection, it is perfect safety and very reliability. This elevator complies with the ideal elevator running curve, and the motor is accurately adjusted by the vector control software, so it is more comfortable. In addition, the VWF elevator is 40% more power saving than the traditional one.The elevators produced before the 1990s didn't adopt VWF, and most of these elevators are still at work, so there is a good market prospect for VWF control technique to reconstruct the traditional elevator. As to the technique alteration work, utilizing most of the primary elevators' durable mechanisms can save 2/3 of the investment, and take less time. Very technical index after the reconstruction reaches the GB10060-93 standard, and the reconstructed one has the same running effect as a newly produced.This paper, based on the introduction of the elevator's basic structure, expatiates the drive and control principle of elevator, and analyzes how to use the PLC to program controlling process. The implementation project of elevator's VWF control system based on PLC and transducer is studied and proposed. Last, notice and resolvent about problems during the construction, debugging and experimentation in the project are put forward.The research mentioned in this paper has been applied to the alteration project, and wins economic and social benefit well. |
