AC Motor Control for Construction Machinery Energy Regeneration
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Solution Overview
Problem
Existing hydraulic control devices for construction machinery driven by AC electric motors do not effectively reduce electric power consumption when battery life is high, and they have low energy regeneration efficiency during braking operations.
Innovation Solution
The device includes oil pressure detection and electric current integration means to adjust AC power supplied to the AC electric motor, allowing for variable power usage based on working oil pressure and current integration values, and sets different limit values for regenerative electric current to optimize energy regeneration during braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electric motor operates at high output continuously, then the operational performance is maintained, but the electric power consumption increases unnecessarily
Solution Approach 1:
The patent applies dynamics by making the electric motor output variable rather than fixed. The control device dynamically adjusts the motor output based on real-time detection of hydraulic actuator demand and battery state, allowing the system to operate at optimal power levels for each working condition rather than maintaining constant high output
Solution Approach 2:
The patent implements feedback control through detection means that continuously monitor hydraulic actuator oil pressure and battery remaining life. This feedback information is processed by the control device to automatically adjust the electric motor output, creating a closed-loop system that responds to actual operational needs and battery status
2Loss of energy
If the regenerative electric current limit is set high, then the energy regeneration efficiency is improved, but the operational feel during braking deteriorates
Solution Approach 1:
The patent applies dynamics by making the regenerative electric current limit variable rather than fixed. The control device dynamically adjusts the current limit based on the detected revolving speed, allowing high regeneration at high speeds where operational feel is less sensitive, and lower regeneration at low speeds where smooth braking is more critical for operator comfort
Solution Approach 2:
The patent changes the parameter of regenerative electric current limit based on operating conditions. By varying this parameter according to revolving speed detection, the system optimizes the balance between energy regeneration efficiency and braking smoothness for different operational scenarios
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 solution enables reduced electric power consumption during low-output operations and improved energy regeneration efficiency while maintaining a satisfactory operational feel, allowing for energy conservation and efficient power utilization in construction machinery.
Implementation Method 1
an AC electric motor 33 for driving the hydraulic pumps 32a, 32b
Implementation Method 2
when revolving is braked, the electric motor is actuated with power generator characteristics and the battery is recharged with the generated electric power
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Provided are hydraulic pumps (32a, 32b) for discharging working oil, a group of hydraulic cylinders (35), a traveling motor (36), an operating device (17) operated in order to control the actuating of the group of hydraulic cylinders (35) and the traveling motor (36), an electric motor (33) driven by the hydraulic pumps (32a, 32b), a battery (41) for outputting DC power, an inverter (43) for inverting the DC power from the battery (41) to AC power and supplying the AC power to the electric motor (33), mode switching means (17a) operated in order to adjust the magnitude of the AC power supplied to the electric motor (33), and a control device (44) for performing control for adjusting the magnitude of the AC power supplied to the electric motor (33).