Slewing Motor Velocity Limiting for Battery Overcharge Protection
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Solution Overview
Problem
Electrically-driven slewing-type shovels face inefficiencies in regenerative energy capture due to high charge levels in the electric storage device, leading to energy loss and insufficient braking force, with potential damage from overcharging.
Innovation Solution
A slewing-type working machine with an electric slewing motor, an electric storage device, and condition detecting means to monitor the storage device's capacity and charge level, implementing velocity limiting control when the storage device is under abnormal conditions to prevent overcharging and ensure efficient energy regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking is performed with high charge level in electric storage device, then energy regeneration is attempted, but the electric storage device cannot sufficiently take in regenerative electric power leading to energy loss and potential overcharging
Solution Approach 1:
The control means continuously monitors the charge level of the electric storage device and uses this feedback information to adjust the regenerative braking control. When the charge level reaches a predetermined threshold, the control means automatically reduces the regenerative braking force or stops energy regeneration, preventing overcharging while maximizing energy recovery under normal conditions
Solution Approach 2:
The system dynamically changes the regenerative braking parameters (braking force, energy acceptance rate) based on the charge level parameter of the electric storage device. By adjusting these parameters in real-time according to the storage device's state, the system optimizes energy regeneration efficiency while preventing overcharging damage
2Reliability
If velocity limiting control is applied when electric storage device is in abnormal condition, then overcharging is prevented, but slewing operation speed is reduced
Solution Approach 1:
The system dynamically adjusts the slewing velocity based on the real-time condition of the electric storage device. When the device is in normal condition, full velocity is permitted. When abnormal conditions are detected (high charge level, temperature issues, capacity degradation), the control means automatically applies velocity limiting to reduce the mechanical stress and energy input, protecting the storage device while maintaining operational capability
Solution Approach 2:
The control means proactively limits velocity before damage can occur to the electric storage device. By detecting abnormal conditions early and preemptively reducing operational stress through velocity limiting, the system prevents potential overcharging or thermal damage while maintaining safe operation
3Reliability
If regenerative braking force is increased to improve stopping performance, then slewing stop precision is improved, but risk of overcharging electric storage device increases
Solution Approach 1:
The control system uses feedback from the charge level monitoring to dynamically adjust the regenerative braking force. When the electric storage device has sufficient capacity, higher regenerative braking force is applied for precise stopping. When the charge level approaches the threshold, the control means automatically reduces the regenerative component of braking force, preventing overcharging while maintaining adequate stopping performance through complementary braking mechanisms
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 overcharging of the electric storage device while maintaining appropriate slewing braking force by efficiently regenerating energy during slewing operations, even under conditions of reduced capacity due to temperature or aging.
Implementation Method 1
an electric slewing motor which causes the upper slewing body to slew, and which generates regenerative braking force and regenerative electric power during slewing braking of the upper slewing body
Implementation Method 2
an electric storage device which functions as an electric power source for the electric slewing motor, and which is capable of being charged with the regenerative electric power to regenerate slewing energy of the upper slewing body
Data Source
AI summary
A slewing-type working machine includes: an electric storage device capable of being charged with regenerative electric power for regenerating slewing energy of an upper slewing body while functioning as an electric power source for an electric slewing motor; an electric storage device and electric storage device controller detecting whether the electric storage device is under a normal condition with sufficient capacity to regenerate the slewing energy or under an abnormal condition without sufficient capacity; and a controller controlling a velocity of the electric slewing motor based on a result of detection by the electric storage device and electric storage device controller, wherein the controller performs a velocity limiting control for limiting a maximum velocity of the electric slewing motor when the electric storage device is under the abnormal condition.