Research On Electric-mechanical Thermal Energy Conversion Device And Its Parameters Based On Rotational Electromagnetic Theory

In design of traditional electric machine, the losses produced in electro- mechanical energy conversion process should be reduced as much as possible for a favorable performance of electric machine as motor or generator. Whereas a new electric-mechanical-thermal energy conversion devive could be implemented based on the inverse problem of losses and temperature rise in electric machine and the production origin of losses in electromagnetic theory, in which the input energy (electrical energy, wind energy, and hytro-energy etc.) is converted to heat energy fully and effectively. In this dissertation, an electric-mechanical- thermal energy conversion devive scheme is produced and the system and associated issues are analysed theoretically and experimentally. Main works of this dissertation are as follows:Firstly, the scheme of the electric-mechanical-thermal energy conversion devive is introduced. And the structures are introduced according to the input energy for various forms of energy could be used as system input energy such as electric energy, wind energy hytro-energy, and so on. The electric-mechanical- thermal energy conversion devive with input electricity energy consist of hybrid-magnetic-circuit multiple-coupling motor and rotational electromagnetic heater. The mathematical modeld of hybrid-magnetic-circuit multiple-coupling motor and the rotational electromagnetic heater are established. Further the operation mechanism of the hybrid-magnetic-circuit multiple-coupling motor and rotational electromagnetic heater are discussed with the distribution of heat source inside analyzed and the energy flow of the heater presented.Then the heat power produced by induced current in stator bars is discussed analytically based on the phase diagram of the heater under steady operation. Under ideal condition, the heat power produced by eddy current in stator iron and the input torque are derived analytically with surface mounted PM rotor. Thereby speed and torque characteristics of heat power produced by eddy current in rotational electromagnetic heater are presented associated with practical heater structure dimensions. And the influences of different structure dimensions (including pole numbers, PM poles arc coefficient, PM depth, stator iron thickness and air-gap length) on heat power are analyzed in detail.For the distribution of electromagnetic field is complicated in practical rotational electromagnetic heater due to its mechanical structure, the existence of water flow pipes, nonlinear magnetic property of materials and the influence of temperature on materials, finite element method is used to analyze its electromagnetic field, and calculation method for its heat power characteristics and torque characteristics is presented, also a prototype is manufactured for related experimental verification. Further with several factors (including bar numbers, pole numbers, air-gap length, and temperature) taken as a starting point, the influences of structure parameters of heater on its output heat power under the same operation condition are analysed. Based on the distribution of magnetic field in heater with slots, it is obtained that the inleakage depth of flux into stator increases as there are slots in the stator, and the influences of slot width and slot numbers on the heater's performance under different speed are analyzed.The thermal network model with seven nodes for rotational electromagnetic heater with closed slots is established, and calculation method for elements in the thermal network model is presented. Thus the relation curve between temperatures in each node and heat power is obtained and thermal problem with variable heating sources in nodes is effectively overcome. And steady state temperature rise of prototype's mathematical model and verified by experiment. Besides, sensitivity analysis of node temperature is conducted, and the influences of thermal resistances between each node and heat power in each node on node temperature are analyzed, the changing rule of PM node temperature with both node heat power and thermal resistances is obtained at the same time.In the last the energy consumption test platform for the electric-mechanical- thermal energy conversion devive is built up and the test method for evaluating system input electric energy and output heat energy is presented. And High heat transfer efficiency of electric-mechanical-thermal energy conversion devive is verified through comparison test for heater prototype and two set of electro-thermal heating devices. Meanwhile the mechanism for scale prevention and removal effect in the electric-mechanical-thermal energy conversion devive is analysed and preliminary experimental verified.Both theoretical and experimental research showed that the new type of electric-mechanical-thermal energy conversion devive introduced in this dissertation has not only a high thermal efficiency, high temperature lifting gradient, but also magnetization and softening effect on water medium, scale prevention and removal effect and a favorable energy saving effect. It would be a new and effective choice as heating device.