Swing Motor Torque Control for Uneven Coil Heating
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Solution Overview
Problem
In work machines with electric motors, uneven coil temperature increases during low-speed or zero-speed swing operations can lead to motor faults due to inadequate cooling and the need for multiple temperature sensors, which is impractical due to cost and space constraints.
Innovation Solution
A work machine with a swing structure driven by an electric motor, equipped with a controller that adjusts the upper limit torque based on swing speed, using a single swing speed detecting device to prevent excessive coil temperature rises by reducing torque when the swing speed is zero or low.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an electric motor is used to drive the swing structure, then energy saving is improved through regeneration, but coil temperature increases unevenly during low-speed or zero-speed operations
Solution Approach 1:
The patent applies dynamics by making the upper limit torque variable based on swing speed. The controller dynamically adjusts the torque limit according to the detected swing speed, reducing torque when speed is low or zero to prevent uneven coil heating, while allowing full torque when speed is sufficient for effective cooling.
Solution Approach 2:
The patent changes the torque parameter dynamically based on swing speed conditions. By monitoring swing speed and adjusting the upper limit torque accordingly, the system prevents excessive coil temperature rise during low-speed operations while maintaining full performance during normal operations.
2Measurement precision
If multiple temperature sensors are installed to detect coil temperatures, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the temperature sensing function from multiple coil temperature sensors and replaces it with a single swing speed detecting device. By inferring coil temperature conditions from swing speed, the system achieves adequate temperature monitoring without the complexity of multiple sensors.
Solution Approach 2:
The patent uses swing speed as an intermediary parameter to indirectly monitor coil temperature conditions. Instead of directly measuring coil temperature with multiple sensors, the system uses swing speed detection to infer thermal conditions and adjust torque accordingly.
3Temperature
If the upper limit torque is reduced when swing speed is zero, then coil temperature control is improved, but productivity decreases during swing press operations
Solution Approach 1:
The patent applies dynamics by making torque limitation conditional on swing speed. The system dynamically switches between torque limitation (at zero or low speed) and full torque availability (at sufficient speed), optimizing both temperature control and productivity based on real-time operating conditions.
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
Prevents electric motor faults during swing press operations and related scenarios by managing torque and temperature effectively, enhancing operational reliability without the need for multiple temperature sensors.
Implementation Method 1
a swing speed detecting device that detects rotational speed of the electric motor as swing speed of the swing structure
Implementation Method 2
a controller that controls torque of the electric motor, wherein the controller reads the swing speed of the swing structure detected by the swing speed detecting device to thereby control such that, when the swing speed is 0, an upper limit torque of the electric motor is smaller than a maximum torque value
Implementation Method 3
an electric motor for driving the swing structure
Implementation Method 4
When an electric motor performs powering or regeneration, heat can be generated for causes of electrical resistance and friction
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
A work machine prevents a fault in a swing electric motor if an uneven coil temperature increase occurs in the swing electric motor during swing press operation and related operations. The work machine includes: a swing structure (20); an electric motor (25) for driving the swing structure; an electricity storage device (24) connected to the electric motor; an inverter (52) for driving the electric motor; a swing control lever unit (72) that issues a command to drive the swing structure (20); rotational speed detecting device (25a) that detects swing speed of the swing structure; and a controller (80) that controls torque of the electric motor (25). The controller (80) reads the swing speed of the swing structure (20) detected by the rotational speed detecting device to control such that, when the swing speed is zero, the torque of the electric motor (25) is smaller than a maximum torque value and, when the swing speed is a first rotational speed higher than zero, the torque of the electric motor (25) is the maximum torque value.