Elevator Control Device Torque Compensation
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Solution Overview
Problem
High-speed elevators experience speed-dependent loss torque variations, leading to insufficient feedforward compensation, resulting in start shocks and speed overshoots, which worsen ride comfort due to excess or deficiency of torque.
Innovation Solution
A control device with a model torque calculating section, storage section, speed-dependent loss torque calculating section, and driving torque calculating section, which calculates and compensates for speed-dependent loss torque to improve feedforward compensation, including a rotary body temperature estimator to simplify equipment configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If feedforward compensation using only torque T(x, L) is used, then the control structure remains simple, but speed control performance deteriorates at high speeds due to insufficient compensation of speed-dependent loss torque
Solution Approach 1:
The torque compensation is segmented into two independent parts: position-dependent torque T(x, L) and speed-dependent loss torque Tloss(V). This segmentation allows each component to be calculated and compensated separately, maintaining control structure simplicity while improving speed control performance through dedicated loss torque compensation.
Solution Approach 2:
The speed-dependent loss torque Tloss(V) is calculated in advance based on the instruction speed value V* and added to the model torque instruction value before actual motor execution. This preliminary calculation and compensation of speed-dependent losses prevents speed deviations and start shocks, improving reliability without adding complex real-time control structures.
2Ease of operation
If feedforward compensation with torque T(x, L) is used, then the control implementation remains straightforward, but speed deviations occur due to excess or deficiency of torque at high speeds
Solution Approach 1:
The total torque instruction is segmented into position-dependent components T(x, L) and speed-dependent components Tloss(V). This segmentation maintains straightforward implementation of position control while adding a separate, simple speed-dependent compensation term that directly addresses high-speed torque deficiencies, improving speed control accuracy without complicating the overall control implementation.
Solution Approach 2:
The compensation approach changes from using only position parameters (x, L) to incorporating both position parameters and speed parameter (V). By calculating Tloss(V) based on instruction speed and adding it to the torque instruction, the system adapts to speed-dependent loss variations, eliminating torque excess or deficiency at high speeds while maintaining ease of implementation through parameter-based calculation.
3Device complexity
If conventional feedforward compensation is used, then the control system remains simple, but start shocks and speed overshoots occur due to insufficient torque compensation
Solution Approach 1:
The speed-dependent loss torque Tloss(V) is calculated in advance from the instruction speed value V* and added to the model torque before motor execution. This preliminary compensation prevents torque deficiencies during acceleration and deceleration, eliminating start shocks and speed overshoots without requiring complex control systems or additional sensors.
Solution Approach 2:
The control system calculates and applies counteracting torque Tloss(V) in advance to compensate for anticipated speed-dependent losses. By preemptively adding this compensation to the torque instruction, the system prevents harmful effects like start shocks and speed overshoots before they occur, maintaining simple control system architecture while eliminating harmful factors.
Data Source
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AI summary
Provided is a control device of an elevator improving the speed control performance by performing feedforward compensation. The control device includes a model torque calculating section which calculates, on the basis of a speed instruction value for an electric motor, a model torque instruction value of the electric motor, a storage section which stores the relationship between the speed-dependent loss torque of the electric motor which varies due to variations in the rotation speed of the electric motor and the rotation speed of the electric motor, a speed-dependent loss torque calculating section which calculates, on the basis of a detected value of the rotation speed of the electric motor, a speed-dependent loss torque value correlated to the detected value, and a driving torque calculating section which calculates a torque instruction value by adding the speed-dependent loss torque value correlated to the detected value to the model instruction value.