Study On The Electromagnetic Compatibility Of Elevator Electrical System

After decades of efforts, especially the reform and opening-up the elevatorindustry in China has developed rapidly during the national construction. There isgreat demand for elevator products. The elevator is a kind of electromechanicalproduct. Like the general electrical products, when working it will produceelectromagnetic interference on surrounding equipments through the power line withthe conductive emission, harmonic emission and electromagnetic emission, etc. It canaffect or even damage the normal use of other equipments.This research is supported by the AQSIQ science and technology planning project--research on the electromagnetic compatibility (EMC) test of elevators. In the11elevator EMC tests of GB/T24807and GB/T24808, the most tough certification fordomestic elevators is the conducive continuous voltage disturbance.This paper focuses on the conductive continuous voltage disturbance test,considering of its poorly low pass for elevator enterprise. The electrical system isdecided as analysis object, which is the most widely used system in elevator today,consist of VVVF speed regulation system and asynchronous motor. Firstly, theconductive EMI interference mechanism of the elevator electrical system is analyzed.Then equivalent high-frequency models of the conductive EMI propagation paths ofthe elevator electrical system are built in detail. And a representative elevatorfrequency converter and three-phase asynchronous motor for elevator are used asexperimental objects to obtain parameters after model established. By SABERsimulation software, the high frequency model of common mode interference anddifferential mode interference is simulated, and the compositive EMI emissionspectrum is obtained. Finally, in order to validate the credibility of simulation results,experiments are designed according to the standard requirements of the conductioncontinuous disturbance voltage in GB/T24807. The experimental results show thatthe simulation waveforms fit well with the experiment waveforms. The waveformsdisplay that their amplitude decay with frequency increasing. The interferenceamplitude is very close in the starting-frequency band and the end-frequency band.For the middle-frequency band, an error about10dBuV occurs, but a decline about-40dBuV/dec is still reasonably presented through the whole test frequency range. This result means that this meth is a high significant help for elevator manufacturersevaluating their product on conductive EMI issue. It provide an estimation way ofelevator electrical systems to do corrective actions in advance before applying forEMC commission test, and will effectively save expensive EMC test costs and timewaste.Because the experiments and simulation results both show that the conductiveEMI of the electrical system is exceed the limit of relative national standards, a furtherexperiment is carried out with additional input EMI filter. The experimental resultsshow that the installation of input EMI filter can obviously reduce the conductiveemission. It’s an effective way to improve the EMI suppression for passing therelative electromagnetic compatibility standards.