Design And Experimental Study Of Hybrid Generator For Self-Powering Wheel Speed Monitoring System

On the other hand,the development of the Internet of Things is inseparable from the advancement of sensor technology.Through the internet interconnection between sensors,the world becomes digital and intelligent.In recent years,intelligent networked vehicles have been able to share and monitor information such as road conditions and vehicle driving status through Internet of Things technology,in which sensors play a major role.In vehicle systems,the monitoring of wheel speed is related to the safety,energy saving and comfort of the automobiles.Therefore,accurately monitoring the wheel speed of the car in real time is of great significance for the control and monitoring of the vehicle.Traditional wheel speed sensors should be supplied by the additional battery,and other power-consuming modules are required to work during data transmission,which makes the chemical battery need to be replaced periodically and cannot provide a more continuous power source to supply the sensing system.The discarded chemical batteries will cause pollution to the environment.Therefore,this paper proposes a self-powered real-time wheel speed monitoring system.The system is composed of a hybrid generator integrating piezoelectric,electromagnetic and triboelectric power generation technologies,a low-power Microcontroller Unit(MCU,a signal recognition and transmission module),and a signal processing unit(a waveform conversion circuit).The main research contents are as follows:Firstly,using physics theories covering magnetic field science,material mechanics,piezoelectricity,electromagnetism,and triboelectricity,the mathematical model of piezoelectric,electromagnetism and triboelectricity is established,and the influencing factors of the output power of the each power generation is analyzed according to the mathematical model.It provides theoretical support for the design of subsequent hybrid generators.Secondly,combined with the basic theoretical analysis of hybrid generator and the application of the hybrid generator,the structure of the composite generator is designed.The hybrid generator is installed in a position coaxial with the wheel to harvest the rotational energy of the wheels into electrical energy to power the electrical equipment in the system.The piezoelectric unit is supported by the cantilever beam,which can make the piezoelectric plate produce large deformation.The magnetic repulsive force is used as the external excitation,which can effectively avoid the collision between the piezoelectric vibrator and the rotor.The electromagnetic power generation unit consists of magnets on the rotor and coils on the stator.When the wheel rotation rotated,the magnet and the coil produce relative motion,which can convert mechanical energy into electrical energy.The triboelectric generating unit adopts the working mode of sliding-mode freestanding,which only needs to be connected wire in the stator shell,without the connect additional electrodes on the stator,so that the stator operation is not affected and can adapt to the high frequency working environment.In particular,the electrode of the triboelectric generating unit is divided into two parts: a energy-channel and a sensing-channel.The energy-channel mainly harvests the rotational energy of the wheel.The sensing-channel is used for monitoring the rotation speed of the wheel.In addition,using simulation software to simulate the power generation process of each power generation unit in the working state of the hybrid generator,which verifies the feasibility of power generation of each power generation unit.Then the prototype of hybrid generator is processed and produced by 3D printing technology.Finally,the experimental test system is built,and the output performance of the each power generation unit under different body parameters and different external excitations is systematically studied to determine the best prototype body parameters.Moreover,by using of the experimental and practical application test,the maximum output performance and the best connection method of the three power generation units under different connection methods are determined to maximize the output performance of the hybrid generator.Combined with circuit design and programming methods,a self-powered wheel speed wireless monitoring system is established.The experimental results show that when the three power generation units are connected in parallel,the instantaneous power of the hybrid generator is 168.2 mW,which can supply power to the low-power MCU,a waveform conversion circuit in the self-powered system and meet the power requirements of hygrometer sensors and low-power LEDs.On the other hand,there is a good linear correlation between the voltage signal frequency collected by the sensing channel of the triboelectric generation unit and the wheel rotation speed,so that the wheel rotation speed can be sensed.The designed waveform conversion circuit can convert the voltage signal into a square wave signal that can be recognized by MCU,and realize the recognition of vehicle speed information by MCU.In the experiment of wheel speed test,there is a good linear relationship between the wheel speed tested by MCU and the actual wheel speed,and the average error rate is 1.9 %.The proposed system realizes self-powered wheel speed monitoring and wireless sensing functions.This work provides a new idea for the application of self-powered wireless sensing technology to the automotive field.