Permanent Magnet Synchronous Toothless Traction for Elevator 20180830

Professional elevator installation manufacturer explains how permanent magnet  synchronous toothless traction machine works.

Structure of Permanent Magnet Synchronous Toothless Traction Machine:
Traction machine, also called reducer, is a device used for elevator. Usually, it is placed in the engine room on the top floor. The rope sheave of traction machine tows elevator and counterweight. This machine consists of turbine reducer, rope sheave, electric motor, coupling, brake and base etc.

Permanent magnet synchronous toothless traction machine is made up of permanent magnet synchronous motor, traction sheave and brake system. Thanks to its high performance permanent magnetic material and special design of electric motor, traction machine is low in speed and high in torque. Traction sheave and brake wheel are concentric coupled and installed on the CDE drive end of motor. Brake system is made up of brake shoe, brake wheel, brake arm and brake scotch.

Working Principles and Features of Permanent Magnet Synchronous Toothless Traction Machine:
Working principles and features of permanent magnet synchronous toothless traction machine: the power of motor is carried from CDE drive end to traction sheave, thus torque is outputted. And the friction between traction sheave and cable drives the elevator. When the elevator stops, brake scotch jams on the brake wheel. Thus, the elevator keeps still.

Permanent magnet synchronous toothless traction machine adopts rare earth material, outer rotor-structure, permanent magnet synchronous motor driving. Worm gear is removed from this machine which is a perfect combination of concentric drive technology, digital variable frequency technology and group computer combination technology. All those factors endow it lots of qualities: small in size, high driving efficiency, quiet, energy-saving, long lifetime, comfortableness and low maintenance rate.

Gear reducer is removed and traction sheave is directly installed in CDE drive end of motor. Without mechanical loss of gear reducer and excitation loss of asynchronous motor, power factor has narrowed almost to1. This efficient machine consumes 40% less energy than asynchronous AC geared traction machine. Different from narrow high- efficiency-range of asynchronous traction machine, synchronous traction machine has flat efficiency curve which means it has an advantage in energy conservation even in the case of low loading rate.

Asynchronous VVVF motor is outclassed by permanent magnet synchronous toothless traction machine. As traction sheave is free from variance of instantaneous angular velocity caused by manufacturing precision, this machine is quieter and more comfortable. It can be used in fine elevator.

Compact structure and small volume of traction machine enable it be installed in small engine room. The design of supporting parts, base, for instance, has optimized, which means it can bear more weight. Without gear reducer, it can get rid of oil spill. As a result of the adoption of fine bilateral-seal bearing, there is no need of lubrication and maintenance in most cases. Schematic drawing of permanent magnet synchronous toothless traction machine is as shown in Figure 2.

Operating System of Permanent Magnet Synchronous Toothless Traction Machine:
Three-phase AC variable frequency power supply that has a servo transducer inside is adopted in permanent magnet synchronous toothless traction machine. The process that transducer slows down or speeds up the traction machine is call braking. Braking makes power return from traction machine to transducer. When transducer brakes traction machine, regenerated power that can be adopted by transducer is equal to power consumption of transducer.

When regenerated power maybe greater than power consumption, the voltage of DC bus in transducer increases. That is the reason why suitable BR (brake resistance) is added to the operating system of traction machine — to release regenerated power. When traction machine operates in low speed and heavy current, the disconnection of the output circuit of transducer may lead to severe arc discharge. As a result, KC is installed between transducer and traction machine. Only when the output of transducer is off can the KC come in to use.

---Posted by Elevator Magnets   Manufacturer China Rare Earth Magnet Limited on 20180830