Research On The Control System Of A Free-Piston Stirling Permanent Magnet Linear Generator

Free-piston Stirling engine has the advantages of compact conformation,high efficiency and less pollution. It has great potential in the areas of space technology, nuclear energy applications, solar power applications and heat recovery. Linear generator has the advantages of fast response, high efficiency, high precision, etc. It becomes the research focus in the field of motor and its control research. The power generation system composed of both machines has the advantages of high efficiency, energy conservation and less pollution. It will promote the development of new energy application.In this paper, the mathematical models of Free-piston Stirling engine and permanent magnet linear generator are analyzed, the system simulation work is done. The Stirling engine power output control determinants are analyzed. The different control strategies of the start control and power generation control are researched.The system simulation models of start-up stage and power generation stage are established in MATLAB / Simulink and the system simulation work is done. Waveforms of the simulation results verify the feasibility of the control strategies.The control system hardware including the drive circuit and the control circuit is design. The drive circuit is composed of power supply circuit, power drive, isolation circuit, detection circuit and protection circuit. The control circuit is composed of TMS320F2812 DSP controller and peripherals circuit, power supply circuit position detection circuit and fault signal processing circuit. The system uses linear variable differential transducer (LVDT) to detect the linear motor mover position, and the drive and conditioning circuit is designed for LVDT.The control system software includeing the main program and the interrupt handling program is designed. After the system resets, the timer, AD module and PWM modules are initialized, timer interrupt and PWM protection interrupt are enabled, the interrupt service routine is implemented when the interrupt conditions are met.Finally, a cylindrical-type permanent magnet synchronous linear generator is used for the experimental prototype. A brushless DC motor is used as the prime motor to simulate the free piston Stirling engine. Crankshaft and connecting components are used to implement the transformation from rotation to linear motion. The experiments of start-up stage and power-generation voltage regulator stage are carried out to test the current loop, obtain the motor mover position curve data and verify the stability of voltage adjustment.