基于反电动势法的航模电调的设计要点详解.docVIP

摘 要 本文首先介绍了目前常见的无刷直流电机的基本组成和工作原理，接着比较了有位置传感器和无位置传感器控制两者之间的区别，并阐述了各自的优缺点，随后给出了无位置传感器众多的控制方法，重点分析了反电动势的检测方法，之后介绍了换相策略、PWM调制方式以及闭环启动控制原理。最终确定选择ATmega8单片机为核心，自主设计了控制系统的硬件电路，重点包括反电动势的过零检测电路、电压电流信号检测电路、逆变电路。结合了无刷直流电机驱动的要求和MEGA8芯片特点，抛弃了传统的使用6个N沟道控制的逆变电路，而是使用3对P和N沟道的MOSFET控制的全桥逆变电路。考虑到芯片必须安全工作，在设计中加入了过压和过流保护电路。 本设计中，最为关键的就是要知道转子的准确位置，才能准确的换相。我们采取了一只种十分巧妙的方法，即对虚拟中性点进行过零检测，从而得到反电势的过零点，最终完成对无位置传感器的无刷直流电机的控制。 关键词： 无刷直流电动机 反电动势法 过零检测 Abstract This paper describes the current structure and operating principle of the brushless motor, and then compares the differences between operations with a position sensor control and without a position sensor control. This research shows the numerous controlling methods of Sensorless. It focuses on the Back-EMF detection method, then it introduces the commutation strategy, PWM modulation and closed-loop control principle to start. Eventually it chooses ATmega8 microcontroller as a core element to self-design control system hardware circuit, highlighting zero-crossing detection circuit, voltage and current signal detection circuit and driver circuit. It combines brushless motor drive requirements and MEGA8 chip features, uses full-bridge inverter circuit 3 P and N -channel MOSFET control rather than the traditional use of six N-channel control of the inverter circuit. To make sure the chip can be operated safely, over-voltage and over-current protection circuit are designed. In this design, the detection of the rotor position is a key part of the overall control system, completing the Back-EMF zero crossing test by taking a virtual neutral point zero crossing test. Finally the control of the position sensorless brushless DC motor is done. Key word：rushless DC motor Back-EMF Zero-crossing detection 目 录摘 要 I Abstract II 1 绪论 1 1.1 无刷直流电机发展现状 1 1.2 无刷直流电机研究意义 1 1.3 无刷直流电动机的控制方法 1 1.4 本设计的研究内容 2 2 系统整体设计方案 4 2.1 无刷直流电机的结构 4 2.2 无刷直流电机工作原理 5 2.3 研究方法和技术路线 6 2.4 反电势法的基本原理 6 2.5 逆变电路 9 2.6 换相和调速 10 3 硬件电路设计 12 3.1 硬件原理框图 12 3.2