Elevator Control Device Unbalance Torque Estimation
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Solution Overview
Problem
Existing elevator control devices face challenges in reducing abrupt state variations, such as start shock and rollback, due to unbalance torque caused by weight differences between the car and counterweight, and require either a load detection device increasing costs or a disturbance observer that increases calculation load and limits responsiveness.
Innovation Solution
An elevator control device that estimates unbalance torque using a current detection unit, velocity computation unit, and an unbalance torque estimation unit based on the time period from brake release to motor rotation, allowing for reduced calculation load and improved responsiveness without a load detection device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a disturbance observer is used to estimate unbalance torque, then the responsiveness for suppressing unbalance torque influence is improved, but the calculation load of computing means increases
Solution Approach 1:
The patent extracts only the essential elements needed for unbalance torque estimation (brake release timing and motor rotation timing) from the complex disturbance observer methodology. By taking out only the critical time period measurement rather than implementing the full disturbance observer algorithm, the system achieves sufficient responsiveness while dramatically reducing calculation load on the computing means.
2Measurement precision
If a load detection device is used to detect car load weight, then the accuracy of unbalance torque estimation is improved, but the cost and device complexity increase
Solution Approach 1:
The system uses existing components (brake control unit and rotation amount detection unit) to provide the information needed for unbalance torque estimation. Instead of adding a dedicated load detection device, the system makes the existing detection units serve the additional function of providing timing information for torque estimation, thereby avoiding increased device complexity and cost.
Solution Approach 2:
The rotation amount detection unit performs multiple functions: it detects both the motor rotation amount for normal operation control and the specific timing of motor rotation start for unbalance torque estimation. This multi-functionality eliminates the need for separate load detection hardware while maintaining estimation accuracy.
3Reliability
If a scale start-up system is used to compensate unbalance torque, then the abrupt state variations of the car are prevented, but the cost and installation complexity increase
Solution Approach 1:
The system performs preliminary estimation of unbalance torque by measuring the time period from brake release to motor rotation start before the actual elevator movement begins. This preliminary action allows the control system to pre-calculate the compensation torque needed, ensuring smooth start-up without requiring complex installation procedures or additional hardware adjustments.
Data Source
AI summary
Proposed is an elevator control device in which an unbalance torque estimation unit configured to estimate an unbalance torque in a motor is implemented in accordance with such a new finding that the unbalance torque can be estimated based on a first time period from an output change of a brake state command signal for switching an operation state of a brake from a braking state to a releasing state to a time when the motor starts a rotating operation along with release of the brake, and on a positive or negative sign of a velocity signal obtained when the motor starts rotation. As a result, as compared to the related art, a smaller calculation load can be achieved. Further, the elevator control device can have a sufficient responsiveness for suppressing an influence of the unbalance torque.