Test Stand Torque Control via Inner Effective Torque Decoupling
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Solution Overview
Problem
Current test stand control methods struggle to accurately control the torque of drive units during dynamic test runs due to the strong coupling of rotational speed and torque via mass inertia, leading to poor control results and the inability to independently manage effective torque, especially in internal combustion engines where inner torque cannot be directly measured.
Innovation Solution
The method decouples rotational speed and torque by controlling the inner effective torque, which is calculated using measured values and known mass inertia, allowing for better control through feed-forward control and consideration of actuating dynamics using a transfer function to compensate for delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the conventional control method N/MEFF is used where the load machine controls rotational speed and the drive unit controls effective torque on the connecting shaft, then the control system is simple to implement, but the torque control accuracy deteriorates during dynamic test runs due to strong coupling via mass inertia
Solution Approach 1:
The patent segments the torque control into two independent components: effective torque (measured on connecting shaft) and inertial torque (calculated from mass inertia and rotational acceleration). By controlling these separately through feed-forward strategies, the system achieves accurate torque control during dynamic operation without increasing overall system complexity.
Solution Approach 2:
The patent applies preliminary action by calculating the required inertial torque in advance based on the desired rotational speed profile and known mass inertia. This feed-forward approach anticipates the torque needed for acceleration/deceleration, allowing the control system to prepare and apply the correct torque before dynamic changes occur, thereby improving torque control accuracy.
2Ease of operation
If the effective torque on the connecting shaft is controlled during dynamic test runs, then the control system can operate with available measurements, but the ability to independently manage inner effective torque deteriorates due to coupling with rotational speed via mass inertia
Solution Approach 1:
The patent introduces an intermediary calculation step that decomposes the total torque into effective torque (measured on connecting shaft) and inertial torque (calculated from mass inertia). This intermediary representation allows the control system to independently manage inner effective torque while still using available measurements, thereby improving torque management capability and control reliability.
3Adaptability or versatility
If stationary operating points are used for testing, then the test stand can meet basic testing requirements with limited technology, but the ability to perform high-dynamic test runs deteriorates due to insufficient control capability
Solution Approach 1:
The patent transitions from static control (stationary operating points) to dynamic control by implementing feed-forward strategies that continuously adapt to changing operational conditions. The system calculates and applies torque corrections based on real-time rotational acceleration and known mass inertia, enabling accurate control during high-dynamic test runs without requiring overly complex control technology.
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 enables more accurate control of drive units during dynamic test runs by decoupling rotational speed and torque, improving control accuracy and addressing the limitations of previous methods by directly managing inner effective torque and accounting for actuating dynamics.
Implementation Method 1
the strong coupling of rotational speed and torque via mass inertia
Implementation Method 2
the drive unit controls the given effective torque MEFF on the connecting shaft
Data Source
AI summary
Aspects of the present disclosure are directed to a method for controlling the torque of a drive unit on a test stand. Accordingly, one embodiment of the present disclosure is a method for controlling an inner effective torque of the drive unit via a unit controlling unit, wherein an inner effective desired torque is determined from the given courses of the rotational speed and the torque of the drive unit and a known mass inertia of the drive unit, and an inner effective actual torque is determined during the operation of the drive unit on the test stand from measured values of the load machine and/or of the drive unit and/or of the connecting shaft and/or of a known mass inertia of the drive unit.