1. Operational characteristics of elevators Relevant research has shown that passenger comfort is not related to speed, but to acceleration, and even more so to the rate of change of acceleration. Therefore, it is required that starting and braking must be smooth and comfortable. The acceleration is generally below 0.9 m/s and an S-shaped acceleration and deceleration method is adopted. The lifting and lowering speeds are as fast as possible, generally 30 to 105 m/min. In addition, if the acceleration (or deceleration) torque is large when starting or stopping, there will always be a slight impact at the moment of starting (or decelerating). In order to eliminate this feeling and ensure smooth operation, an "S-shaped torque control mode" has been added to some elevator-specific frequency converters, as shown in Figure 1. Figure 1a) is the non-S-shaped torque control mode, and Figure 1b) is the S-shaped torque control mode. In the S-shaped torque control mode, the torque gradually increases or decreases when starting or stopping, so that passengers do not feel any impact. 2. Working state of the motor (1) Car fully loaded (car weight > counterweight weight) ① The car rises into electric state, and the mechanical characteristics are in the first quadrant. ② When the car descends, it is in reverse generator mode, and its mechanical characteristics are in quadrant 4. (2) Car light load (car weight < counterweight weight) ① When the car rises, the weight of the counterweight will pull the car up, causing the motor speed to exceed the synchronous speed, and it is in generator mode, with its mechanical characteristics in quadrant 2; ② When the car descends, it is in reverse generator mode, with its mechanical characteristics in quadrant 3. For details, please click: