A Single-phase Input Variable Frequency Speed Control System Without Electrolytic Capacitor

In traditional variable frequency speed control system, there are some problemswith Power Factor Correction(PFC), such as loss increase, low power density, highcost, which cannot satisfy the development demand of variable frequency speedcontrol system for high power factor, small seize and light weight and low cost. Forthis purpose, this article does a research on no electrolytic capacitor frequencyconversion speed regulation system.This paper studies deeply on variable frequency speed control system withlarge capacity electrolytic capacitor and frequency conversion speed regulationsystem without electrolytic capacitor, and analysis them comparatively. Thestimulation experiment shows that electrolytic capacitorless frequency conversionspeed regulation system has an obvious advantage in aspect of power factorimprovement. Therefore, it is the main power topology in this article.It is needed to introduce the power control strategy, since there is strong powercoupling between rectification and inverter side in electrolytic capacitorlessfrequency conversion speed regulation system. Therefore, a power control algorithmbased on PR controller is proposed in this paper, which overcomes the difficulty thattraditional PI controller of the power is hard to achieve accurate tracking the accomponent and realizes the input current of power grid voltage phase tracking byusing PR controller to make the system power loop closed.To further improve power tracking system response speed and solve theproblem of PR controller to low frequency gain less, a new type of power controlleris put forward in this paper. This controller has higher open loop gain in both lowfrequency and specified resonant frequency, thus ensure accurately track the powerof the ac and dc components. Then we further improve the input power factor of thesystem.This paper preliminarily sets up a small capacity electrolytic capacitorfrequency conversion speed regulation system, and carries on simple experimentalverification towards the new power controller which proposed in it. In addition, thesystem has carried on a simulation experiment under the condition of power gridvoltage fluctuation and frequency pulsation, the result shows that this system hasstrong ability to resist the disturbance.