Research On Programmable Pulsed Electric Field Power Supply For Food Sterilization

The hot food sterilization technology is attracting more and more attention because it can keep the food fresh and natural flavor,and among them the food high-voltage pulsed electric field sterilization technology has been one of the research hot spots in recent years.Taking the food high-voltage pulsed electric field sterilization power as the research object, this paper analyses its basic principle and development trend.Comparing several common types of high voltage pulse power generator, considering the comprehensive factors such as economy,high efficiency, saving energy,and finally choose the type of high voltage pulse power generator with pulse pressure.Currently,the high leakage inductance of the high voltage pulse power pulse transformer cause bigger rising or falling along the output pulse,in order to solve the problem,this paper proposes an improved method of auxiliary winding pulse transformer. And in order to solve the problem of the large current may destroy circuit switching devices,this paper presents a kind of improved topology structure of IGBT in parallel flow.In food sterilization technology, the smaller rising along the output pulse has the higher sterilization efficiency,and the traditional pulse transformer has the problem of low transmission efficiency in using due to the large leakage inductance,this paper designed a new type of pulse step-up transformer to reduce the leakage inductance by increasing the auxiliary winding based on the original pulse transformer.The method is proved feasible using the mathematical model,the experimental results confirm the validity of the theoretical derivation and achieved the desired effect. The power of the food high-voltage pulse electric field sterilization and the primary side current of pulse transformer are very large,which may damage the switch devices.But because of the power converter circuit inevitably has the problem of uneven distribution of the stray inductance which will cause uneven dynamic in parallel flow of IGBT so as to damage the switch tube, so in order to solve the problem of uneven dynamic flow,this paper designed a topology by increasing auxiliary resistance in IGBT emitter and made simulation analysis using Pspice simulation software, the simulation results verify the theory is reliable.A power supply for high-voltage pulsed electric field food sterilization was designed.With the maximum output voltage of 30 kV, maximum output pulse current of 200 A,and the maximum frequency of 5kHz, its controller used STM32 simplifies the system structure. This paper presents the structural design of the machine, and measured the experimental waveforms, the final experimental results show that the theories in the article put forward to solve all the problems are correct.