| Dielectric Elastomer(DE)is a kind of dielectric thin film material with elastic deformation ability.The elastic capacitance can be made by covering the upper and lower surfaces of DE with flexible electrodes.When the two ends of the flexible electrode are connected to the DC voltage source,the dielectric elastomer will shrink along the direction of the power line and extend in the plane perpendicular to the power line.This phenomenon is called electrostrictive effect.Reversely utilizing electrostrictive effect,DE capacitor will become a power production unit,namely Dielectric Elastomer Generator(DEG).In the past research,DEG power generation needs high voltage DC power supply to provide bias voltage,which restricts the use of DEG technology in practical projects.In this thesis,piezoelectric materials are used to provide bias voltage for DEG,and a self-bias circuit is used to accumulate and reuse the energy generated by DEG.A new piezoelectric biased DEG is designed to solve the problem of self-supply in DEG power generation technology.This thesis focuses on the following aspects of research:(1)The principle of dielectric elastomer power generation technology is analyzed,and the variation of voltage in the process of dielectric elastomer power generation is theoretically deduced.The relationship between the magnitude of Maxwell stress and the area tension of DEG under three bias modes of constant electric field,constant voltage and constant charge is analyzed.The hyperelastic constitutive model is studied and the method of establishing the constitutive model is understood.The typical constitutive models include Mooney-Rivlin model,Ogden model,Neo-Hookean model,etc.According to the characteristics of dielectric elastomer materials,Ogden model is chosen as the constitutive model of dielectric elastomer.The relationship between the variation of DEG voltage and its strain under bias voltage is deduced,and the mechanical model of DEG is constructed.The principle of piezoelectric power generation is analyzed,and the expression of the output form of piezoelectric power is given.(2)According to the principle of DEG power generation,the electrical model of DEG is established.Combined with the mechanical model of DEG,the DEG is modeled and simulated by using MATLAB/Simulink software.The piezoelectric bias circuit model is built by using Simulink’s Simscape library,and the piezoelectric bias DEG is established by combining it with the DEG simulation model.The model is simulated by using AC power supply to simulate the piezoelectric output waveform.The principle of self-bias circuit and DEG cooperation is analyzed.The self-bias circuit is modeled and simulated by using MATLAB/Simulink software.(3)The vibration system of piezoelectric sheet is built by using function signal generator,power generator and vibration exciter.The electric energy generated by piezoelectric sheet is stored in capacitor and used to provide bias voltage for DEG.VHB4910 is selected as DE material,DS-001 is selected as DEG flexible electrode,and the support frame of circular DE sheet is made by acrylic plate,and the crank slider mechanism is driven by step motor.The experiment proves that the piezoelectric chip can provide bias voltage for DEG,and it is found that the output voltage of DEG is proportional to the bias voltage.(4)The embedded experimental system is designed with STM32 single chip computer.The system adopts the idea of modularization and hierarchical design.The design flow of the system is described from two aspects of software and hardware.In the hardware part,the minimum system of STM32,JTAG debugging interface,UART interface and FSMC interface are introduced in detail.In the software part,the integrated development environment MDK is used to edit and compile the program.STM32 firmware library functions,uC/OS and uC/GUI are invoked in the programming process,which shortens the development cycle of the system and realizes the basic functions of DEG voltage data acquisition and bias voltage supply control. |
