Test Bench Control System Resonance Damping via Predictive Feedback

Solution Overview

Problem

Conventional control systems for test benches with connecting shafts to dynamometers face challenges in damping resonances at higher frequencies due to inherent system delays, which limit the ability to adjust set-point torque rapidly and can lead to resonance issues and potential damage.

Innovation Solution

A control method that compensates for system delays by using both current actual values and predicted, system-delay-free values from previous cycles, allowing for in-phase damping of resonances by separating transient and predictive portions and feeding back a modified actual value to the control system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the natural frequency of the connecting shaft is increased to transmit high-frequency torque components, then the ability to transmit high-frequency torques is improved, but resonance occurs in the working range of the engine

Engineering Contradiction:

Improvefrequency response capabilityVSAvoidsystem stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The control system performs preliminary actions by predicting future resonance conditions based on the periodic nature of engine operation. It identifies upcoming critical speeds and pre-adjusts control parameters to prevent resonance excitation before it occurs, rather than reacting after resonance has started

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts control parameters based on real-time operating conditions, including current engine speed, acceleration rate, and predicted future states. This allows the control system to adaptively manage the connecting shaft's natural frequency relative to engine operating frequencies, preventing resonance while maintaining high-frequency torque transmission capability

Inventive Principle:

Principle #15Dynamics

2Device complexity

If a conventional control system with measured actual values is used, then the control system is simple to implement, but the system delay prevents effective damping of high-frequency resonances

Engineering Contradiction:

Improvecontrol system complexityVSAvoidsystem delay

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The control system performs preliminary actions by predicting future resonance conditions based on the periodic nature of engine operation. It identifies upcoming critical speeds and pre-adjusts control parameters to prevent resonance excitation before it occurs, rather than reacting after resonance has started

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from periodic measurement of engine parameters (torque, speed, vibration) combined with predictive modeling to continuously update control actions. The feedback loop incorporates knowledge of engine cycle periodicity to anticipate future states and adjust control parameters proactively, reducing the effective delay in resonance damping

Inventive Principle:

Principle #23Feedback

3Stability of the object's composition

If the connecting shaft acts as a low-pass filter to prevent resonances, then system stability is improved, but the dynamics of load or drive torque is limited

Engineering Contradiction:

Improveresonance dampingVSAvoidtorque dynamics response

Core Design Contradiction:

Stability of the object's compositionVSSpeed

Solution Approach 1:

The control system performs preliminary actions by predicting future resonance conditions based on the periodic nature of engine operation. It identifies upcoming critical speeds and pre-adjusts control parameters to prevent resonance excitation before it occurs, rather than reacting after resonance has started

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts control parameters based on real-time operating conditions, including current engine speed, acceleration rate, and predicted future states. This allows the control system to adaptively manage the connecting shaft's natural frequency relative to engine operating frequencies, preventing resonance while maintaining high-frequency torque transmission capability

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9134712B2Method and control arrangement for controlling a controlled system with a repeating working cycle

Publication Date: 2015.09.15 AVL LIST GMBH

AI summary

When arrangements with a repeating working cycle such as, for example, in the case of engine test benches, are being controlled, resonances which have to be damped by the control system are often excited by the test specimen (for example an internal combustion engine) in the working range of the arrangement. The invention proposes for this purpose a control concept in which a modified actual value rist<sub2>—</sub2>mod is determined from a current actual value rist<sub2>—</sub2>akt of the control system and from a predicted imminent system-delay-free actual value on the basis of the actual value of a previous working cycle, and said modified actual value rist<sub2>—</sub2>mod is fed to the control system.