Elevator Hoisting Motor Torque Constant from Roundtrip Current
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Solution Overview
Problem
Existing elevator systems face inaccuracies in determining the torque constant of hoisting motors, leading to imprecise motor control and ride quality, as the nominal torque constant values are often too inaccurate and substitute calculations further exacerbate the issue.
Innovation Solution
A method involving a roundtrip in the elevator shaft with constant speed portions in opposite directions to determine the torque constant, using recorded motor current samples, mean values, and mechanical parameters like traction sheave radius and elevator roping ratio, based on equations involving elevator balance and gravitational acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a nominal torque constant value is used from motor type tests, then the parameter determination process is simple, but the accuracy of the torque constant is insufficient
Solution Approach 1:
The patent changes the determination method from using nominal values from type tests to calculating the torque constant based on actual operational parameters (motor current, speed, torque) measured during elevator operation. This transforms the parameter from a fixed nominal value to a dynamically determined value that reflects actual motor performance, thereby improving accuracy while maintaining implementation simplicity through automated measurement and calculation.
2Device complexity
If a substitute torque constant is calculated from nominal current and power values, then the parameter can be obtained without additional measurements, but the estimation accuracy deteriorates
Solution Approach 1:
The patent replaces the electrical calculation method (using nominal current and power values) with a mechanical measurement approach. By measuring actual motor current during constant speed operation and calculating torque from the balance between motor force and gravitational force on the elevator car, the system obtains more accurate torque constant values without significantly increasing device complexity, as the measurements use existing sensors and control systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate determination of the hoisting motor's torque constant, improving motor control precision and enhancing ride quality by eliminating estimation errors.
Implementation Method 1
an elevator hoisting motor, such as a permanent magnet motor
Implementation Method 2
elevator balance, and one or more mechanical parameters related to a force transmission between the hoisting motor and the elevator car
Implementation Method 3
elevator balance, and one or more mechanical parameters related to a force transmission between the hoisting motor and the elevator car
Data Source
AI summary
A method for determining a torque constant of a hoisting motor (302) of an elevator system (300). The method comprises performing (110) a roundtrip in an elevator shaft (340) by an elevator car (310) by utilizing the hoisting motor (302), wherein the roundtrip comprises a constant speed portion (21) in a first direction and a constant speed portion (22) in a opposite second direction. The method comprises determining (120) a motor current of the hoisting motor (302), such as recording samples thereof, during at least the constant speed portions, determining (130) a mean value of the motor current in the constant speed portions (21, 22), and determining (140) the torque constant based on the mean value, an elevator balance, and one or more mechanical parameters related to a force transmission between the hoisting motor (302) and the elevator car (310). An elevator system (300), an elevator control unit (1000), and a computer-readable memory medium are also disclosed.