Electric Motor Torque Control in Electro-Hydraulic Systems
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Solution Overview
Problem
Electro-hydraulic systems face challenges in effectively controlling torque to prevent excessive pressure, often requiring pressure-limiting valves that increase complexity and cost.
Innovation Solution
A method and device that control the torque of an electric motor in an electro-hydraulic system by selecting a target torque based on current pressure, determining an actuation signal from a setpoint torque and target torque, and using this signal to limit motor current, thereby eliminating the need for pressure-limiting valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure-limiting valves are used to protect against excessive pressure, then system reliability is improved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical pressure-limiting valve with an electronic control system that uses a torque sensor to detect excessive pressure conditions and automatically reduces motor torque accordingly. This substitution eliminates the need for mechanical valves while maintaining pressure protection functionality through electronic sensing and control.
Solution Approach 2:
The control system continuously monitors pressure conditions through the torque sensor and automatically adjusts motor torque without external intervention. The system serves itself by detecting pressure exceedances and self-correcting by reducing torque, eliminating the need for separate pressure-limiting components.
2Reliability
If pressure-limiting valves are installed in the hydraulic circuit, then pressure protection is ensured, but manufacturing costs increase
Solution Approach 1:
The mechanical pressure-limiting valve is replaced by an electronic torque sensing and control system. This substitution reduces component count and assembly requirements, thereby lowering manufacturing costs while maintaining the essential pressure protection function through electronic means.
Solution Approach 2:
The patent extracts the pressure-limiting function from the mechanical hydraulic circuit and relocates it to the electronic control domain. By taking out the pressure-limiting valve and implementing the function through torque sensing and electronic control, the system reduces hardware complexity and manufacturing cost.
3Power
If the electric motor torque is increased to meet high pressure demands, then system power capability is improved, but the risk of excessive pressure and component damage increases
Solution Approach 1:
The patent implements a feedback mechanism where the torque sensor continuously monitors the actual torque output of the motor. When excessive torque (indicating excessive pressure) is detected, the control system receives feedback and automatically reduces the torque command, creating a closed-loop control that prevents pressure damage while allowing high power operation when needed.
Solution Approach 2:
The torque sensor and control system provide preliminary anti-action by detecting and counteracting excessive torque before it can cause damage to hydraulic components. The system preemptively reduces torque when threshold values are exceeded, preventing harmful pressure spikes before they occur.
Data Source
AI summary
A method is used to control a torque of an electric motor of an electro-hydraulic system. The method includes selecting a value of a set point torque depending on a current pressure in a hydraulic circuit of the electro-hydraulic system. The method also includes determining a control signal for controlling the torque of the electric motor using a target torque and the set point torque.