新型变极起动永磁同步电动机研究

In view of the poor starting capacity of ordinary line-start permanent magnet synchronous motors, a novel line-start permanent magnet synchronous motors with pole-changing capacity is proposed. At the first stage of starting, the stator winding runs with lower pole number, and will be switched to run with higher pole number by pole-changing at suitable opportunity. The pulsating torque and braking torque during starting process can be greatly reduced, thus the starting capacity can be improved. To study the proposed motor deeply, a novel pole-changing winding, which has the advantages of being easy to switch, measuring speed without other equipment, and obtaining good starting and running performances, is put forward. A transient simulation model is proposed to consider the effect of inequality of stator winding pole number and permanent magnet pole number, and the method for calculating corresponding inductances is studied. The transient model is used to study the effects of pole number combination on the starting and pull-in performances. The method to calculate the main torque components for starting with stator winding of lower pole number is deduced. The transient model is also used to study the effects of motor status on torque, current and pull-in capacity. Then the switching strategy and measuring methods is obtained, and the corresponding switching equipment is developed. The study of this project will improve greatly the starting capacity of line-start permanent magnet synchronous motors, and lay good theory foundation for the design, manufacturing, and application of pole-changing permanent magnet synchronous motors.

鉴于异步起动永磁同步电动机起动方面的缺点，本项目提出一种新型变极起动永磁同步电动机，采用新型变极绕组，起动初期定子绕组少极数运行，在适当时机切换到多极数运行，大幅度削弱波动转矩和发电制动转矩，提高起动能力。提出一种切换方便、自身有转速检测能力、兼具良好起动能力和运行性能的新型变极绕组；建立计及绕组极数与永磁磁场极数不等影响的双极数动态仿真模型，提出相应的电感参数计算方法，并进行动态行为的分析计算，据此研究极数组合等设计参数对起动能力的影响，给出相关参数的设计原则；导出绕组少极数状态下各转矩分量的计算方法；研究切换时电机的状态量对冲击转矩、冲击电流、永磁体退磁及牵入同步能力影响的规律，据此提出切换控制策略和检测控制技术，构建满足工程要求的切换控制装置。本项目的完成，将显著改善异步起动永磁同步电动机的起动能力，为新型变极起动永磁同步电动机的设计、制造和推广奠定良好的理论基础。

异步起动永磁同步电动机因受自身工作原理、现有结构和起动方式的影响，在起动过程中会存在较大的发电制动转矩和脉动转矩，导致起动能力差。为解决该问题，本项目研究了一种新型变极起动永磁同步电动机，主要研究工作如下：.(1) 新型变极起动永磁同步电动机的结构、工作原理及电磁特性分析。定子上采用所需开关少、切换方便、自身具有转速检测能力、兼具良好起动能力和运行性能的变极绕组，可实现少极数绕组起动、多极数绕组运行，显著提高电机起动能力；推导出定转子极数不同时空载感应电动势的解析表达式；分析了不同转/定子极数比时起动过程中的各转矩分量及产生机理，提出了变极起动过程中转矩计算方法。.(2) 针对小功率系列异步起动永磁同步电动机，提出了不同电机极数与定子槽数配合时的变极起动方案。研究了变极起动方案中少极数绕组极数的选择；结合不同极数下取不同定子槽数时各变极绕组的设计过程，推导出可行的极槽配合原则。.(3) 新型6/8变极起动永磁同步电动机的研究。设计了一台380V、30kW、6/8变极起动永磁同步电动机，对其展开深入研究，主要包括：电枢磁场、空载反电势、堵转转矩和电流、发电制动转矩、脉动转矩、额定负载下的起动过程、可起动的最大负载转矩和最小起动电压、电机参数和转矩计算、通过适当减小转子电阻以同时提高牵入同步能力、稳态性能分析。.(4) 变极起动永磁同步电动机绕组切换过程及控制策略的研究。建立双极数动态仿真模型，研究了不同状态下绕组切换时的转速、转矩、电流以及永磁体退磁情况，以确定对电网、电机和负载冲击小、有利于电机起动和牵入同步的绕组切换控制策略。.(5) 样机试验。基于电磁设计方案，制造了一台380V、30kW的6/8变极起动永磁同步电动机进行试验，验证分析、计算的正确性以及该6/8变极起动永磁同步电动机的可行性和优越性。.本项目的完成，将大幅度改善异步起动永磁同步电动机的起动性能，为变极起动永磁同步电动机的设计、制造和推广奠定良好的理论和技术基础。