Sensorless Hydraulic Pump Motor Control for Demand-Based Flow
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Solution Overview
Problem
Hydraulic systems in working vehicles face inefficiencies due to the need for continuous operation of the hydraulic pump when not all hydraulically actuated devices require fluid flow, leading to energy losses and cumbersome maintenance, and the reliance on internal combustion engines for pump operation results in unnecessary energy consumption.
Innovation Solution
A hydraulic system with electric motors coupled to hydraulic pump assemblies, controlled by a sensorless motor controller, which adjusts rotation speed to vary hydraulic fluid output, eliminating the need for rotor positioning sensors and allowing for fixed displacement pumps, thereby optimizing fluid flow and reducing inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotor positioning sensor is used in the electric motor system, then control accuracy and dynamic response are improved, but device complexity and cost increase
Solution Approach 1:
The patent removes the rotor positioning sensor from the electric motor system, extracting the sensing component while maintaining control functionality through alternative means such as current sensing and control algorithms that do not require direct rotor position feedback
Solution Approach 2:
The control system uses the motor's own current draw and electrical characteristics to infer rotor position and speed information, allowing the motor to self-diagnose and self-regulate without external sensing components
2Reliability
If the hydraulic pump operates continuously when the ICE is running, then hydraulic fluid is always available, but energy consumption increases unnecessarily
Solution Approach 1:
The electric motor operates periodically based on actual hydraulic demand rather than continuously, activating only when hydraulically actuated devices require fluid flow and remaining idle when no hydraulic operation is needed
Solution Approach 2:
The system changes the operational parameters of the motor from continuous operation to demand-based intermittent operation, adjusting rotation speed and power consumption according to real-time hydraulic system requirements
3Quantity of substance
If excess hydraulic fluid output is returned via bypass circuit or relief valve, then pump output is reduced, but energy loss increases
Solution Approach 1:
The system dynamically adjusts the electric motor's rotation speed to match the actual hydraulic flow requirements of the actuators, eliminating the need for static pump output reduction mechanisms like bypass circuits or relief valves that waste energy
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 configuration enhances system responsiveness and efficiency by decoupling hydraulically actuated devices, reducing energy waste, and improving control accuracy without the need for rotor position sensors, resulting in a more efficient and reliable hydraulic system operation.
Implementation Method 1
an electric motor coupled to the hydraulic pump assembly such that output of hydraulic fluid from the hydraulic pump assembly is varied by adjusting the rotation speed of the electric motor
Data Source
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AI summary
A working machine comprising a hydraulic system, the hydraulic system comprising: a hydraulically actuated device; a hydraulic pump assembly for supplying a variable output of hydraulic fluid to the hydraulically actuated device; an electric motor coupled to the hydraulic pump assembly such that output of hydraulic fluid from the hydraulic pump assembly is varied by adjusting the rotation speed of the electric motor; a motor controller configured to: generate a motor control signal for operating the electric motor based on a motor speed command signal, wherein the hydraulic system does not comprise a rotor positioning sensor arranged to sense the rotational position of a rotor of the electric motor.