Comparison of elevator motors

Below these are several elevator motor speed control system to make a comparison.
    2.1.1 and AC drive systems, DC speed control system is simple, speed performance, deflector structure is simple, the governor has long been the dominant transmission towel, but with the theory and technology of AC variable speed development, more and more places are AC elevator motors instead. This was mainly due to DC elevator motor speed control system of the following disadvantages:
1) DC elevator motor structure is complicated and costly, failure and more difficult to maintain and workload, often due to spark large impact on production.
2) segments of the commutator machine capacity limitations of the capacity of the elevator motor, voltage and speed, contact the current transfer and limit the DC elevator motor applications.
3) on the rotor armature, elevator motor efficiency is low, poor heat dissipation, cooling cost is high. To improve the ability to change, reduce armature leakage inductance, the rotor becomes chunky, moment of inertia increases affect the dynamic performance.
2.1.2 induction elevator motor drive system features:
General Elevator asynchronous elevator motors are used with cage rotor, simple structure, strong and durable. Elevator control for asynchronous elevator motor speed regulator from the beginning to use the scalar control voltage and variable frequency, recapitulation becomes flux-oriented vector control. Not only improve the accuracy of the elevator motor system control, operating efficiency has improved.
 But the induction elevator motor drive system has several disadvantages:
 1) from the side of the stator asynchronous elevator motor excitation, therefore, the elevator motor power factor is low, causing inverter device input power is low. And compared with the capacity of a synchronous elevator motor, the use of large capacity inverter device.
 2) In the high-performance vector control induction elevator motor speed control system, the rotor parameters will be affected by temperature changes, resulting control error, affecting its control precision.
3) asynchronous elevator motor to improve the power factor and efficiency, the need to minimize the air gap between the stator and rotor, which makes manufacturing difficult.
2.1.3 PMSM system features: [12] [13] [14] [15] [16]
Permanent magnet synchronous elevator motor can be divided into two categories, one is powered back EMF waveform and current waveform is an ideal square wave (actually trapezoidal wave) of the brushless DC elevator motor magnet synchronous motors another water two waveforms are sine , is usually said permanent magnet synchronous elevator motor. Among their frequency control system is to use a rotor position detection device constitutes a closed-loop control, the decision by the position of the rotor frequency corresponding power tube off, making the inverter output frequency and elevator motor speed are always in sync, so-called self-control governor system. Whenever the elevator motor rotor turned one pair of poles, the output current of the inverter just change a cycle, current and rotor always in sync, does not appear out of step. Frequency by adjusting the input voltage to the motor for speed control characteristics due to the former is similar to the DC elevator motor, and replaced with electronic commutation of the latter mechanical commutation, the abolition of the brush, so named brushless DC motor In general, for an elevator and a permanent magnet synchronous brushless DC elevator motor controller are installed in the rotor position detecting means, but there are brushless DC elevator motors with the counter-electromotive force detection position, called the application without position sensing techniques.
Brushless DC elevator motor high efficiency, high power factor, overload, small size, easy to maintain. With the emergence of new magnetic materials, making the synchronous motor with high dynamic and static quality. The system control method is very simple. Disadvantages are: manufacturing process is slightly more complex than the induction elevator motor, the most fatal disadvantage is the low speed pulsation obvious. This will result in slow elevator comfort worse.
    2.1.4 The permanent magnet synchronous elevator motor is characterized by:
    I) torque ripple, steady speed, dynamic response quickly and accurately, strong overload. Than asynchronous elevator motors for synchronous motor torque disturbance has stronger capacity, can make a relatively fast response. When the induction elevator motor load torque changes, the required elevator motor slip also followed changes, namely the elevator motor speed change accordingly, but the system inertia of the rotating part of the elevator motor impede rapid response. Synchronous elevator motor load torque changes, as long as the elevator motor power angle to make the appropriate changes in the rotational speed was maintained constant in the original synchronous speed, the inertia of the rotating part does not affect the rapid response to the torque elevator motor. The maximum torque of permanent magnet synchronous elevator motor can reach more than 3 times the rated torque of the elevator motor system in large changes in load torque conditions are very favorable and stable operation
2) high power factor, high efficiency. Water-magnet synchronous elevator motor and the induction elevator motor compared to the excitation current not reactive, can significantly improve power factor, to reduce the stator current and stator copper loss, but also in the stable operation without rotor copper losses, in turn, can decrease total loss due to reduced fan capacity or even remove the fan, thus reducing or even eliminating the corresponding wind friction loss. Thus, it is more efficient than the same specifications asynchronous elevator motor can be increased by 2 - 8 points. Compared with the electrically excited synchronous motors, permanent magnet synchronous elevator motor excitation power eliminates the need for improved efficiency. Moreover, the water magnetic synchronous elevator motor at 25% to 120% of rated load range
Circumference can be maintained in both the high power factor and efficiency, energy saving light load operation is more significant in the long-term use
Can greatly save energy.
    3) Small size and light weight. In recent years, with the continuous application of high-performance permanent magnetic materials, permanent magnet synchronous elevator motor power density is greatly improved, compared with the capacity of asynchronous electric elevator motor, has a larger volume and weight reduction, making it in many special occasions applied.
    4) structural diversification, and wide application of water to touch the rotor synchronous motor structure is extremely diverse, resulting in features and performance of many different species, from one industry to the agricultural workers from civilian to defense, from daily life to aviation aerospace, power tools from simple to high-tech products, almost all-encompassing.
    5) high reliability. With DC elevator motor and electrically excited synchronous elevator motor, has no brushes, simplifying the structure, increasing reliability.
    Sine wave magnetic synchronous elevator motor water gap magnetic flux density due to their spatial distribution load nearly sinusoidal shape, reducing the harmonic components of the air gap magnetic field, thus reducing the magnetic field caused by the harmonics of the various harmonics of the torques and the loss and electromagnetic vibration torque caused by harmonics, improve the efficiency of the elevator motor, and the elevator motor runs more smoothly when rotated, the noise has also been reduced. Meanwhile, the sine wave PMSM vector control in accordance with a variety of methods to constitute frequency control system, high-performance, high-precision drive, the dynamic response requirements of the occasion of its application particularly promising.