Variable Speed Compressor Current Limiting Control
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Solution Overview
Problem
Mobile electrically driven compressors face issues with exceeding maximum electric current limits, leading to inefficient operation, potential safety hazards, and unnecessary power limitations when connected to electricity supplies with varying current capacities, especially when used with other electrical equipment.
Innovation Solution
An electrically driven mobile compressor with a variable speed control system and electronic controller that limits the electric current drawn by adjusting the speed or pressure based on set maximum values, calculated from the machine's characteristics and desired pressure or flow rate, ensuring safe operation within the supply's limits without mechanical inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressor power is limited by means of a controllable mechanical inlet valve, then the maximum electric current drawn is limited according to the available electrical connection or fuse, but the partial closure of the inlet valve leads to a lower power and a greater flow resistance of the gas to be compressed that greatly reduces the efficiency of the compressor
Solution Approach 1:
The patent replaces the mechanical inlet valve control system with an electronic control system that regulates compressor power by controlling the electric motor's power input. This substitution eliminates the mechanical flow resistance caused by partial valve closure while maintaining current limit compliance through electronic regulation of motor torque and speed.
Solution Approach 2:
The patent changes the control parameter from mechanical valve position to electric motor power parameters (current, voltage, frequency). By adjusting motor power parameters electronically, the system limits current draw without creating flow resistance, thereby maintaining compressor efficiency while ensuring reliable operation within electrical connection limits.
2Reliability
If a fuse is used to disconnect the compressor when maximum current is reached, then the maximum electric current is limited to protect the supply source, but other applications can also be taken out of service and significant time loss occurs for reactivation
Solution Approach 1:
The patent implements preliminary action by proactively monitoring and limiting the compressor's current draw before the fuse disconnects the supply. The electronic control system continuously adjusts motor power to stay within the maximum current limit, preventing fuse activation and ensuring continuous operation of both the compressor and other electrical applications.
Solution Approach 2:
The patent employs feedback control by continuously monitoring the actual current draw and comparing it to the maximum permissible current. The control system adjusts motor power in real-time based on this feedback, ensuring current limit compliance while maintaining operational continuity and preventing disruptive fuse cutouts.
3Reliability
If the compressor is limited to a maximum current equal to the maximum available current minus the combined maximum current of other connected electrical consumers, then the available current and power of the compressor are needlessly limited when consumers do not utilise their maximum current
Solution Approach 1:
The patent implements dynamic current limit adjustment by continuously monitoring the actual power consumption of connected electrical consumers and adjusting the compressor's current limit accordingly. Instead of using a static conservative estimate, the system adapts the current allocation in real-time, allowing the compressor to utilize available power capacity dynamically while ensuring total current remains within supply limits.
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 maintains efficient operation by limiting current draw without causing flow or pressure losses, is easy to implement, and provides clear power usage indicators, ensuring the compressor operates within safe and optimal parameters.
Implementation Method 1
an electric drive motor with a variable speed control coupled to the compressor element or pump element
Data Source
AI summary
Electrically driven mobile compressor or pump, comprising at least one compressor element or pump element for supplying a pressurised fluid to a network of consumers of such pressurised fluid; an electric drive motor with a variable speed control coupled to the compressor element or pump element and a controller for the variable speed control of the electric drive motor as a function of the flow rate of compressed gas and/or pressure demanded by the network, and a connection for connection of the compressor or pump to an electricity supply source, and the controller is provided with an algorithm with which the electric current drawn from the supply source can be limited to a set or adjustable maximum value by controlling the speed.