Dynamometer Control Device for Low-Frequency Resonance Suppression
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Solution Overview
Problem
Existing dynamometer control devices fail to accurately control shaft torque in low frequency regions due to interference between engine speed control and shaft torque control caused by viscous drag, leading to resonance phenomena, especially at low engine revolutions.
Innovation Solution
A dynamometer control device that generates a torque current command signal using an integrator and phase lead or lag compensator, with specific transfer functions and constants based on the viscous drag coefficient and moment of inertia of the test piece, to reduce resonance in the low frequency region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dynamometer control device uses conventional shaft torque control without considering viscous drag, then the mechanical resonance at several tens of Hz is reduced, but a new resonance phenomenon occurs in the low frequency region (about 0.5 Hz) when the engine operates at low speeds
Solution Approach 1:
The patent introduces a new control parameter (viscous drag coefficient) into the shaft torque control equation and changes the control strategy by adding a phase lead compensator. This modifies the control parameters to account for viscous drag effects, allowing the system to maintain stability while eliminating low-frequency resonance at idle speeds
Solution Approach 2:
The patent implements feedback control by using the shaft torque detection signal to generate the torque current command signal. The phase lead compensator processes the shaft torque error signal and feeds it back to the inverter, creating a closed-loop control system that actively suppresses resonance phenomena
2Ease of operation
If the engine control device controls engine speed while the dynamometer control device controls shaft torque, then both parameters can be regulated, but interference between the two control systems causes resonance in the low frequency region
Solution Approach 1:
The patent makes the dynamometer control system dynamic by introducing a phase lead compensator that adapts the control response based on the system's actual state. The compensator dynamically adjusts the torque current command signal to prevent interference with engine speed control, allowing both control systems to operate stably together
Solution Approach 2:
The phase lead compensator acts as an intermediary between the shaft torque detection and the torque current command generation. It processes the shaft torque error signal and transforms it into a corrected command signal that prevents control interference, mediating between the two control systems
Data Source
AI summary
The purpose of the present invention is to provide a device for controlling a dynamometer of a test system, wherein the device is capable of controlling shaft torque to a prescribed target torque while minimizing low-frequency-range resonance caused by viscous drag of a test piece. This test system is provided with a dynamometer joined to an engine via a coupling shaft, an inverter for supplying electric power to the dynamometer, a shaft torque meter for detecting the shaft torque produced in the coupling shaft, and a dynamometer-controlling device 6 for generating a torque-current command signal T2 that is sent to the inverter and is generated on the basis of a shaft torque detection signal T12 from the shaft torque meter. The dynamometer-controlling device 6 is provided with an integrator 62 for integrating the difference between the shaft torque detection signal 12 and a shaft torque command signal T12ref, and a phase lead compensator 63 for accepting an output signal from the integrator 62 as an input and performing a phase lead compensation process that uses constants (a1, b1) that are dependent on the viscous drag of the test piece. An output signal from the phase lead compensator 63 is used to generate the torque-current command signal T2.