| In order to alleviate the energy shortage and environmental pollution,automobile energy saving and emission reduction has become one of the important tasks of automobile research and development.However,the application of energy saving and emission reduction technologies such as vehicle lightweight,high-power engine cylinder deactivation makes the engine vibration excitation more complex,which improves the standard of vibration isolation performance of engine mounting system.In complex engine conditions,the engine mount is required to maintain good vibration attenuation ability to meet the needs of consumer comfort.The electromagnetic active engine mount meets the above vibration isolation and vibration reduction requirements.ECU generates control signal,drives the actuator of active engine mount actuator,produces resistance force opposite to the same phase of engine excitation amplitude,and attenuates the engine excitation transmitted to the body.With the change of engine working condition,active egine mount can adjust the resistance of engine vibration in real time,and meet the vibration isolation requirements of dynamic stiffness and damping characteristics of the engine mount.The market prospect of electromagnetic active engine mount is broad,and the research heat in recent years is also higher and higher.This paper is based on the project of "Nanjing Iveco bus NVH technology development"(September 2012-December 2015),"drive axle NVH capacity building based on transmission path and response"(October 2016-December 2018),and "C-class car engine active mounting system technology development"(October 2016-December 2019).This paper deduces the secondary path mathematical model of the electromagnetic active engine mount: the control input of the electromagnetic active engine mount to the active part of the engine electromagnetic active mount,and the control input of the electromagnetic active engine mount to the passive part of the electromagnetic active engine mount.The mathematical model of the secondary path from the control input to the active part is used for parameter analysis.The mathematical model of the secondary path from the control input to the passive part is used for adaptive feedforward control,and the vibration isolation performance of electromagnetic active engine mount is studied.In this paper,the dynamic characteristics of electromagnetic active engine mount and the fast control experiment of Electromagnetic Active Engine Mount based on d SPACE are studied by using the method of combining simulation and experiment.The main research contents are as follows:(1)The engine excitation with cylinder deactivation technology is analyzed.In order to make better use of the active engine mount control to attenuate the excitation transmitted to the vehicle body,the engine mount space layout which has influence on the active engine mount excitation is studied.The excitation of three cylinder engine and four cylinder engine,six cylinder engine and eight cylinder engine with cylinder deactivation technology are analyzed.When the engine is cut off,the formula of reciprocating inertia force remains unchanged,the fundamental frequency of overturning moment decreases and the amplitude of overturning moment increases.It provides an important basis for the application of adaptive feedforward control in active engine mount vibration attenuation.(2)The Lorentz force and magnetic induction of electromagnetic active engine mount actuator are studied.The influence of magnetization mode of cylindrical permanent magnet on magnetic induction and output voltage of magnetic gap is studied by using equivalent magnetic charge method,equivalent current method and finite element method.According to the equivalent magnetic circuit method,the magnetic resistance analytical formula and the Lorentz force formula per unit cross-sectional area are derived.The finite element method is used to study the change of the magnetic gap magnetic induction intensity and Lorentz force of the actuator with the structural parameters of the actuator,which provides a reference for the structural design of the cylindrical permanent magnet moving coil actuator.(3)In order to solve the problem that the assumption of the actual working condition of some active mounts is improper,which is not conducive to the design and control of the active engine mount when establishing the secondary path mathematical model of the electromagnetic active engine mount.The secondary path mathematical model of the electromagnetic active engine mount is deduced according to the structure and performance of the electromagnetic active engine mount.The experiment verifies the mathematical model of the secondary channel of the electromagnetic active engine mount control input to the active part.The sensitivity of the structure and performance parameters of the active mount to the amplitude and phase of the secondary path mathematical model is analyzed.Compared with the traditional secondary path mathematical model,the established secondary path mathematical model needs to consider the influence of engine mass and frame mass,frequency variation characteristics,relative displacement and so on,which helps to shorten the forward design and development cycle of electromagnetic active engine mount,and provides convenience for subsequent optimization.The secondary path mathematical model of active engine mount control input to the passive part is applied to adaptive feedforward control,which provides strong support for the subsequent control development of electromagnetic active engine mount.(4)The control effect of adaptive feedforward control algorithm is compared by simulation.Based on the secondary channel mathematical model of engine electromagnetic active mount,a single channel control model of Fx LMS adaptive filtering algorithm is built.The adaptive feedforward control based on LMS algorithm,normalized LMS algorithm(NLMS),sign-data LMS algorithm,Sign-error LMS algorithm and sign-sign LMS algorithm is simulated by Simulink.The simulation results show that the adaptive feedforward control based on sign-sign LMS algorithm has fast convergence speed and good attenuation effect,which can provide reliable guarantee for the control implementation of engine electromagnetic active mount.(5)In order to solve the problem that the electromagnetic active engine mount test bench can not accurately reflect the loading environment of the active engine mount on the anti vibration rubber dynamic characteristic test machine,a double-layer vibration isolation test bench which is closer to the real vehicle condition is designed considering the influence of tire and suspension.Based on MATLAB / Simulink / RTW,the adaptive feedforward Fx LMS control is used to generate real-time C program code,which is connected and downloaded to d SPACE DS1103 PPC processor board to carry out semi physical simulation experiment of rapid control prototype of constant speed engine vibration active control.The test results show that the vibration acceleration amplitude of the passive end of the electromagnetic active engine mount is reduced by about 78% at the frequency of 60 Hz,and the vibration acceleration amplitude is obviously reduced at the frequency of 120 Hz and 37 Hz.Except for the frequency of 50 Hz,the transmissivity of electromagnetic active engine mount is above 20 d B at all test frequencies.The electromagnetic active engine mount can attenuate the simulated engine vibration of high harmonic and non harmonic simulation engine vibration.The control effect of FXLMS adaptive feedforward control is verified,and the vibration isolation performance of the electromagnetic active engine mount t is tested. |
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