Hydraulic Drive Pressure Control Using Motor Speed Feedback
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Solution Overview
Problem
Current hydraulic drive systems for deep drawing devices face inaccuracies in pressure regulation, especially with variable volume flows and wide pressure ranges, as they fail to account for the necessary rotational speed dependency on both setpoint and actual pressure, leading to unstable and inaccurate control.
Innovation Solution
A method that uses rotational speed as the actuating variable to regulate output pressure in hydraulic drive systems, involving the determination of a setpoint rotational speed main component, error rotational speed, and conversion through a frequency converter to maintain precise and dynamic pressure control, accounting for non-linear malfunctions and disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pressure control is based only on pump characteristics with idealized linear relationship, then control is simple, but accuracy deteriorates with variable volume flows and wide pressure ranges
Solution Approach 1:
The patent implements a feedback control mechanism where the actual pressure is continuously measured and compared with the setpoint pressure. The pressure deviation is fed back to the controller, which adjusts the motor drive's rotational speed to eliminate the deviation. This closed-loop feedback system maintains accurate pressure control across variable volume flows and wide pressure ranges without requiring complex control structures.
2Measurement precision
If rotational speed is used as actuating variable with feedback from actual pressure, then pressure control accuracy improves, but system complexity increases
Solution Approach 1:
The patent replaces complex mechanical pressure control mechanisms with an electrical control system. By using the motor drive's rotational speed as the actuating variable and controlling it electronically based on pressure feedback, the system achieves accurate pressure control without requiring complex mechanical components such as pressure compensating valves or flow control valves. This substitution of mechanical control with electrical control simplifies the overall system structure.
3Ease of operation
If conventional pressure control methods are used, then system operation is simple, but stability deteriorates with variable volume flows and non-linear malfunctions
Solution Approach 1:
The patent employs continuous feedback control where the actual pressure is measured and compared with the setpoint pressure. The controller uses this pressure deviation information to dynamically adjust the motor drive's rotational speed, ensuring stable pressure control even when volume flow varies or non-linear malfunctions occur. This feedback mechanism automatically compensates for disturbances without requiring complex operational procedures.
Solution Approach 2:
The patent implements dynamic control by continuously adapting the motor drive's rotational speed based on real-time pressure conditions. Rather than using fixed control parameters, the system dynamically adjusts the actuating variable (rotational speed) in response to changing operating conditions, including variable volume flows and non-linear malfunctions. This dynamic adaptation maintains pressure control stability across varying operational scenarios.
Data Source
AI summary
A method for regulating output pressure of a hydraulic drive system by using a rotational speed as the actuating variable. The method includes determining a setpoint rotational speed main component of motor drive as a pilot control signal, determining an error rotational speed as a regulating deviation from a comparison of an actual pressure value of the hydraulic drive system and a setpoint pressure value of the hydraulic drive system and adjoining regulating amplifier, adding the determined setpoint rotational speed main component to the determined error rotational speed to create the setpoint rotational speed as the actuating variable, and converting the created setpoint rotational speed into an input rotational speed of the motor drive to drive the hydraulic drive system at the converted rotational speed in order to generate regulated output pressure of the hydraulic drive system which represents actual pressure value.