Engine Control Switching to Feedforward for Asynchronous Motor Startup
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Solution Overview
Problem
Existing methods for controlling internal combustion engines with asynchronous machines face challenges in managing high starting currents, leading to significant speed drops and requiring additional power electronic components, which are undesirable in safety-critical applications.
Innovation Solution
A method that detects electrical characteristics such as current, voltage, or frequency changes during the startup of an asynchronous machine, switching from standard speed control to feedforward control when a predetermined threshold is exceeded, allowing for direct starting without speed drops and enabling predictive load management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct starting of asynchronous machine is implemented, then reliability is improved through fewer components, but speed stability deteriorates due to high starting currents
Solution Approach 1:
The control device detects electrical characteristics (current, voltage, or frequency) and determines characteristic changes in a predetermined time interval. When the change exceeds a first limit value, the system switches from standard speed control to feedforward control before the speed drop occurs, enabling preventive action rather than reactive correction
Solution Approach 2:
The control device continuously monitors electrical characteristics of the generator and uses this feedback to detect the startup phase of the asynchronous machine. The system compares characteristic changes with limit values and adjusts control mode accordingly, creating a closed-loop control system that responds to actual system conditions
2Stability of the object's composition
If standard speed control is used, then speed stability is maintained, but response time deteriorates due to delayed detection of load changes
Solution Approach 1:
By monitoring electrical characteristics and detecting characteristic changes in a predetermined time interval, the system identifies load changes before they manifest as speed drops. The feedforward control mode is activated proactively, allowing the control system to prepare countermeasures in advance rather than waiting for speed deviation to occur
Solution Approach 2:
The system replaces traditional mechanical speed sensing and reaction mechanisms with electrical characteristic monitoring. By detecting current, voltage, or frequency changes, the system achieves faster detection and response times compared to mechanical speed measurement and correction methods
3Stability of the object's composition
If power electronic components are added for soft starting, then speed stability is improved, but device complexity increases and cost increases
Solution Approach 1:
The control device utilizes existing electrical characteristic measurements from the generator for dual purposes: normal operation monitoring and asynchronous machine startup detection. The system repurposes available sensor data to achieve startup management without requiring separate sensing systems or additional power electronic components
Solution Approach 2:
The control device performs multiple functions using the same hardware resources: it monitors generator electrical characteristics for normal operation, detects asynchronous machine startup phases, determines characteristic changes, and switches control modes. This multi-functionality eliminates the need for dedicated startup control hardware
Data Source
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AI summary
The invention relates to a method for the open-loop and closed-loop control of an internal combustion engine (BK), in particular a diesel engine or gas engine, with a generator (G) and asynchronous machine (ASM), comprising the following steps: detecting at least one electrical characteristic variable of the generator, wherein the electrical characteristic variable is selected from current (I), voltage (U) or frequency (f); determining a characteristic variable change in the electrical characteristic variable of the generator in a predetermined time interval; comparing the change in characteristic variable with a first threshold value; and in the event that the change in characteristic variable is greater than the first threshold value, changing from a standard speed control of the internal combustion engine to a feed-forward control.