Hydraulic Pump Speed Control With Motor Acceleration Limits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydraulic drive systems for electrically driven hydraulic work machines, such as excavators, face inefficiencies in pump operation due to constant rotation speed control, leading to excessive energy consumption and reduced responsiveness, especially when handling varying load pressures and low flow rates.
Innovation Solution
A hydraulic drive system that dynamically adjusts the angular acceleration of the electric motor based on hydraulic power consumption, limiting it within a preset maximum allowable power to optimize rotation speed control and prevent excessive current generation, thereby enhancing efficiency and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electric motor operates at constant high rotation speed to ensure sufficient flow rate, then the delivery flow rate of the hydraulic pump is maintained, but the hydraulic pump efficiency decreases due to increased stirring resistance and viscous resistance
Solution Approach 1:
The patent applies dynamics by transitioning from constant rotation speed control to variable rotation speed control. The electric motor's rotation speed is dynamically adjusted based on actual hydraulic load conditions (pressure and flow rate requirements), allowing the system to operate at optimal speeds rather than maintaining a constant high speed that causes excessive resistance and energy loss in the hydraulic pump.
Solution Approach 2:
The patent changes the operational parameters of the electric motor from fixed to variable. By continuously adjusting rotation speed according to real-time hydraulic load demands, the system optimizes the balance between delivering sufficient flow rate and minimizing stirring resistance and viscous resistance in the hydraulic pump, thereby improving overall energy efficiency.
2Speed
If the rotation speed of the electric motor is rapidly increased to respond to sudden actuator activation, then the delivery flow rate increases to meet demand, but excessive current is generated reducing battery life
Solution Approach 1:
The patent applies preliminary action by implementing advance limitation on the rotation speed change amount. Before the electric motor can rapidly accelerate to high speed, the control system pre-establishes a maximum allowable acceleration rate based on battery capacity and power constraints. This prevents excessive current generation by limiting how quickly the motor speed can increase, thereby protecting battery life while still enabling responsive actuator activation.
3Reliability
If the rotation speed of the electric motor is limited to prevent excessive current, then battery life is extended, but the responsiveness of the hydraulic pump to actuator activation is reduced
Solution Approach 1:
The patent applies dynamics by implementing adaptive rotation speed control that balances battery protection with system responsiveness. Rather than using a fixed speed limit, the system dynamically adjusts the maximum allowable rotation speed change based on actual hydraulic load conditions, actuator requirements, and battery state. This allows the system to respond quickly when necessary while preventing excessive current generation that would harm battery life.
4Use of energy by moving object
If the electric motor operates at low rotation speed to save energy, then battery power consumption is reduced, but the delivery flow rate becomes insufficient when high flow rate is demanded
Solution Approach 1:
The patent changes the operational parameters from fixed low speed to variable speed based on demand. The control system continuously monitors hydraulic load conditions (pressure and required flow rate) and adjusts the electric motor's rotation speed accordingly. When high flow rate is demanded, the motor speed increases to meet the demand; when demand is low, the speed decreases to minimize energy consumption, thereby optimizing the balance between productivity and energy efficiency.
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 ensures reliable power consumption within set limits, improves hydraulic pump efficiency, and enhances the responsiveness of actuators by dynamically adjusting rotation speed according to hydraulic load, reducing energy waste and operator discomfort.
Implementation Method 1
an electric motor 1 to drive a hydraulic pump 2
Implementation Method 2
a hydraulic pump 2 to supply a hydraulic fluid to a plurality of actuators 3a to 3h
Data Source
AI summary
In a hydraulic drive system for an electrically driven hydraulic work machine that executes flow rate control of a hydraulic pump by controlling a rotation speed of an electric motor to drive a hydraulic pump to supply a hydraulic fluid to a plurality of actuators, and power consumed by the electric motor reliably limited within a range of preset maximum allowable power without unnecessary degradation of responsiveness of the electric motor. To this end, a controller includes a maximum angular acceleration limitation section (allowable rate computation section and rate limitation section), computes hydraulic power consumed by a main pump, computes a maximum angular acceleration allowed for an electric motor on the basis of a magnitude of the hydraulic power and a preset maximum allowable power consumable by the electric motor, and limits an angular acceleration of the electric motor not to exceed the maximum angular acceleration.