Introduction
The universe and the world in which we currently survive
will almost certainly be unattainable had they not represented innovations in vertical transportation. The Ward-Leonard DC motor drive system was invented in 1893 and
100 years later Variable Voltage and Variable Frequency (VVFD) AC motor drives
emerged for vertical transport. Over the past 30 years, the use of AC voltage
and frequency converters has increased and for many, they have become the best
way to control vertical transport traction machines. The benefits are well
documented and include increased system efficiency, simplified commissioning
and improved ride quality. The question of the quality of the electrical system
power supply is increasingly a concern when choosing and sizing elevator
systems.
Variable Voltage Variable Frequency Drive (VVVF) uses
frequency inverter technology that adjusts the input voltage and frequency
during travel, drawing much less current during acceleration and deceleration
When compared with other drive modes, it can be seen that the VVVF drive offers a low starting current (about 1.8 times the rated current), a high power factor (i.e. better power supply efficiency) with good running quality and a floor levelling. It can reduce motor starting currents by up to 50-80% compared to traditional motor drives. Additionally, equipment wear can also be lower when starting/stopping the engine using the VVVF engine drive.
1 Comments
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