Elevator Motor Control via Field Weakening Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Elevator operating efficiency is compromised due to low maximum speed and acceleration settings that prevent temperature overload, resulting in underutilization of hoisting machine capacity and potential high motor temperatures.
Innovation Solution
An elevator control system that performs speed priority control by maintaining a predetermined rotational speed through field weakening current when a temperature warning is received and switches to torque priority control by reducing the field weakening current to maximize torque output when the temperature warning is active, thereby managing motor temperature and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If maximum speed and acceleration are set low to prevent temperature overload, then motor temperature is controlled, but elevator operating efficiency deteriorates
Solution Approach 1:
The patent implements dynamic speed pattern switching between high-speed and low-speed modes based on real-time temperature conditions. The control device selects appropriate speed patterns by comparing predicted temperature values against reference values, enabling the elevator to operate at high speed when safe and slow down only when necessary to prevent overheating.
Solution Approach 2:
The patent changes operational parameters (speed and acceleration) based on temperature conditions. By switching between different speed patterns with varying maximum speeds and accelerations, the system adapts motor operating parameters to current thermal states, preventing overheating while maximizing efficiency during safe operating windows.
2Reliability
If speed pattern maximums are set low for safety margins, then component overload is prevented, but hoisting machine driving capacity is underutilized
Solution Approach 1:
The patent performs preliminary computation of temperature conditions before elevator operation begins. By predicting temperature evolution based on operation start position, destination, and environmental data, the system determines safe operating parameters in advance, allowing the elevator to operate at or near maximum capacity without risking component overload.
Solution Approach 2:
The patent uses feedback from temperature sensors and predicted temperature values to continuously adjust speed patterns. The control device monitors actual temperature conditions and compares them against predicted values, switching between high-speed and low-speed patterns to maintain reliable operation while maximizing power utilization.
3Speed
If field weakening current is increased to maintain speed, then rotational speed is maintained, but motor temperature increases
Solution Approach 1:
The patent dynamically adjusts field weakening current based on temperature conditions. When temperature is low, maximum field weakening current is applied to achieve high speed. When temperature approaches reference values, the system reduces field weakening current and switches to low-speed patterns, preventing thermal overload while maintaining speed when safe.
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
This approach effectively prevents abnormally high motor temperatures and maintains elevator operating efficiency by optimizing speed and torque control based on temperature conditions, ensuring efficient use of hoisting machine capacity.
Implementation Method 1
a motor (6)
Implementation Method 2
performing speed priority control in which a maximum value of rotational speed of the motor (6) is kept to a predetermined speed by passing a field weakening current to the motor (6)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In an elevator control system, supply of electric power to a motor of a driving machine that moves a car is controlled by a control apparatus. A temperature warning signal is output from a temperature signal generating apparatus to the control apparatus if a temperature of predetermined subject equipment that includes the driving machine reaches a predetermined temperature reference value. The control apparatus performs speed priority control in which a maximum value of rotational speed of the motor is kept to a predetermined speed by passing a field weakening current to the motor when receipt of the temperature warning signal is stopped, and performs torque priority control in which a maximum value of rotational speed of the motor is kept lower than the predetermined speed within a range in which output torque is at a maximum relative to the supply of electric power of the motor by lowering the field weakening current to the motor further than during the speed priority control when the temperature warning signal is received.