Generator Excitation Current Control for Reduced Dead Time
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Solution Overview
Problem
The existing generator control systems experience a significant dead time before supplying power to the vehicle electrical system when activated, leading to inefficient battery charging and reduced generator utilization, especially with frequent engine starts.
Innovation Solution
The method involves quickly ramping up the excitation current of a multi-phase alternating current generator by using the excitation current limiting function without the load response control, followed by a slower increase using the load response function, to reduce the dead time and enhance power delivery to the vehicle electrical system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the load response control function is used to limit the increase in duty cycle over time, then the generator voltage is regulated stably, but the dead time before power supply increases significantly
Solution Approach 1:
The patent segments the excitation current increase process into two distinct phases: a first phase using the excitation current limiting function for rapid current increase, and a second phase using the load response control function for stable voltage regulation. This segmentation allows the system to achieve both fast response and stability by applying different control strategies at different stages.
Solution Approach 2:
The patent applies preliminary action by first using the excitation current limiting function to quickly establish the necessary excitation current before engaging the load response control function. This preliminary rapid increase reduces the dead time while ensuring that the subsequent voltage regulation phase starts from an already established current level.
2Loss of time
If the excitation current is quickly ramped up using the excitation current limiting function, then the dead time is reduced, but the generator voltage may fluctuate
Solution Approach 1:
The patent divides the control process into two sequential segments: first the excitation current limiting function for rapid current buildup, then the load response control function for voltage stabilization. This segmentation ensures that voltage fluctuations during rapid current increase are managed by the subsequent stabilization phase.
Solution Approach 2:
The patent ensures continuity of useful action by seamlessly transitioning from the excitation current limiting function to the load response control function. The load response function continuously adjusts the duty cycle to maintain stable generator voltage even as the excitation current is rapidly changing, ensuring uninterrupted and stable power delivery.
3Power
If the duty cycle is increased suddenly to maximize power output, then the generator delivers maximum power, but the mechanical stress on the drive system increases
Solution Approach 1:
The patent applies preliminary action by first rapidly increasing the excitation current to establish the magnetic field necessary for power generation, then gradually increasing the duty cycle to deliver maximum power. This preliminary establishment of excitation current reduces the mechanical shock when maximum power delivery begins.
Solution Approach 2:
The patent employs dynamic control by using the load response control function to continuously adjust the duty cycle based on actual generator voltage and load conditions. This dynamic adjustment allows the system to deliver maximum power when conditions permit while reducing mechanical stress during transient states, optimizing the balance between power output and mechanical stress.
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 approach significantly reduces the dead time, allowing the generator to supply power earlier when the engine is started, thereby reducing the battery's charging burden and increasing its service life by minimizing unnecessary charge cycles.
Implementation Method 1
The rotor of the synchronous machine 9 carries an excitation winding 5 and is supplied with the excitation current I ERR... The magnetic field of the field winding 5 is typically conducted into the stator via pole claws made of magnetically permeable steel and induces an alternating voltage when rotating in the stator phases
Implementation Method 2
the rectifier 1 converts the alternating voltages of the stator phases into the direct voltage U GEN required for the on-board electrical system 7
Data Source
Figure 1~2
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AI summary
The invention relates to a method for starting the exciting current of a multi-phase alternating current generator upon activating the generator, downstream of which a rectifier for generating a rectified voltage is connected. The rectified generator voltage is regulated via a controller-semiconductor component. An exciting current is adjusted to regulate the generator voltage, wherein the exciting current is in turn adjusted via a duty factor adjusted by the controller-semiconductor component. The controller-semiconductor component comprises an exciting current limiting function for limiting the exciting current to an exciting current threshold value. In addition, there is a load-response-control function in the controller-semiconductor component in order to limit the increase of the duty factor over time. According to the method, in order to start the exciting current, the exciting current is quickly increased to an exciting current threshold value, starting from zero, using the exciting current limiting function. Here, the load-response-control function is not used, so that the increase of the exciting current is not limited by the load-response-control function Upon reaching said exciting current threshold value, an additional increase of the exciting current is carried out using the load-response function. Alternatively, it is possible to use the load-response-control function even with a quick increase of the exciting current; here, however, the load-response-control function should be adjusted by the control device so that the load-response-control function enables a rapid increase of the duty factor over time. After reaching said exciting current threshold value, an additional increase of the exciting current then occurs using the load-response-control function, but having a slower increase of the duty factor over time than previously.