Belt-Driven Starter Generator Torque Control
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Solution Overview
Problem
Belt-driven starter generators experience noise, vibration, and mechanical stress during internal combustion engine starting due to jerky torque changes, which can lead to reduced service life and inefficient belt tensioning.
Innovation Solution
Gradually increasing torque is achieved by pre-energizing the stator winding before the rotor winding reaches maximum excitation current, allowing for earlier belt pretensioning and reduced mechanical load, using a computing unit to control the electrical machine and manage the current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor winding is energized to produce starting torque, then the internal combustion engine can be started, but the belt experiences jerky tensioning causing noise, vibration and mechanical stress
Solution Approach 1:
The stator winding is energized in advance before the rotor winding reaches its full excitation current, so that the belt is pretensioned before the full starting torque is applied. This preliminary action of the stator winding creates a gradual torque build-up that prevents jerky belt tensioning and reduces noise and vibration during engine starting.
2Object-affected harmful factors
If the stator winding is energized early to pretension the belt, then noise and vibration are reduced, but the control complexity increases
Solution Approach 1:
The control unit monitors the current state of the rotor winding excitation and uses this feedback information to determine the optimal timing for energizing the stator winding. By basing the stator energization timing on the actual rotor current state rather than a fixed time delay, the system achieves smooth belt pretensioning with relatively simple control logic.
3Duration of action of stationary object
If the belt is pretensioned before starting, then service life is extended, but the energy consumption increases
Solution Approach 1:
The stator winding is energized partially and temporarily only during the critical starting phase to achieve belt pretensioning, rather than being continuously energized. This partial action during the specific time window before full torque application extends belt service life through smooth tensioning, while the energy consumption is limited to this brief period only.
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 minimizes noise and vibration, extends the service life of components, and ensures a smoother engine start with reduced mechanical load, while also providing cost-effective implementation through software-based control.
Implementation Method 1
A current through a rotor winding of an alternator/starter device is set to a pre-flow field current and a current through a stator winding is set to zero. When a start command for starting the internal combustion engine is received, the current through the rotor winding and the current through the stator winding are each set to a starting current value.
Implementation Method 2
a current through a rotor winding of an alternator/starter device is set to a pre-flow field current
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method for preparing the start-up of an internal combustion engine (300) by means of a belt-driven starter generator (100), which has a stator winding (11) and a rotor winding (12), wherein the starter generator (100) is operated such that the generated torque thereof gradually increases over a duration of more than two rotor winding time constants. Current is fed to the stator winding (11) in such a manner that the generated torque gradually increases over a duration of more than two rotor winding time constants. Current is fed to the rotor winding (12) and, if an excitation current through the rotor winding (12) is below a lower threshold before the current feed, the stator winding (11) is fed with current before the excitation current is above an upper threshold. According to the invention, the belt of the starter generator is pretensioned prior to the actual starting process by means of actuation of the electrical machine and thus lurches, vibrations and noises that occur during the start-up of the internal combustion engine by means of a starter generator can be prevented.