通用变频器的设计

摘要

使异步电动机实现性能好的调速一直是人们的理想,过去如变极调速、绕线转子异步电动机转子回路串电阻调速均属于有级调速；而调压调速虽能平滑调速,但调速范围不大,耗能多,仅限于小功率,无法和直流调速系统相比。随着新技术、新理论的不断发展,变频调速技术应运而生,其控制方式完全可以和直流调速系统相媲美。因此变频器的应用日益广泛，变频器性能的优劣直接影响着电机的运行特性，所以如何提高变频器的优化控制成为变频技术的关键。在变频调速中关键的一项就是控制端SPWM波的产生,它不仅要求电压和频率变化呈线性关系,而且要求输出波形尽可能接近于正弦波,特别是对于一些性能指标要求较高的全控型开关器件如IGBT等,其开关频率很高,因此就要求SPWM波发生器要达到一定的开关频率,基波频率也要求相对较高。为了解决这个问题,可以利用SLE4520这块集成芯片,来生成满足要求的SPWM波。本设计就是利用AT89C51单片机作为控制主机，与三相PWM集成芯片SLE4520配合工作，设置一种SPWM波生成的算法，通过单片机的定时模块产生脉冲，并将其送入SLE4520中，最后将SPWM脉冲送至逆变桥臂上下的IGBT中来控制逆变电路。本设计的优势在于可以通过键盘/显示来进行变频器的智能控制。在不同的工作状态下，可以显示不同的数据，再配合上各种故障保护电路，可以使得变频器安全的工作。

关键词：SLE4520 单片机 SPWM脉冲

ABSTRACT

To achieve good performance asynchronous motor speed is ideal, such as speed regulating pole change motor rotor asynchronous and winding speed rotor circuit resistance of all belong to have stepless speed regulation, And although speed regulating speed can be smooth, but not more than energy-consuming, speed limits, only small power, compared with dc speed control system. With the new technology, the new theory of frequency conversion technology unceasing development, the control mode, and can completely Dc speed control system. But in the frequency conversion control is one of the key is the wave of SPWM not only requires the voltage and frequency variation, and the requirements of a linear relationship between output waveform in sine as close as possible, especially for some performance index to demand higher all-controlling switching device IGBT etc, such as the high frequency switching, so requires SPWM wave generator to reach a certain switching frequency wave frequency also require relatively high. In order to solve this problem, you can use SLE4520 this integration chip, to meet the requirements of SPWM wave generated.This design is to use AT89C51 as host, and three-phase PWM control SLE4520 integrated chips, setting an SPWM wave generated by MCU timing algorithms, and will produce pulses module to SLE4520, finally will SPWM inverter pulse to bridge the arm upper-and-lower IGBT inverter circuits to control. The design of the keyboard/strengths can display for converter intelligent control. In different working conditions, can show the different data, combined with the various fault protection circuit, can make the job security. Keywords：SCM（Single Chip Microcomputer）SLE4520

SPWM(Sinusoidal Pulse Width Modulation)

河南理工大学本科毕业设计论文

目录

摘要.............................................................. I ABSTRACT .......................................................... II 1 绪论. (1)

1.1 交流电动机调速发展现状 (1)

1.2 SPWM控制技术介绍 (3)

1.3 本系统设计的主要内容及意义 (4)

2 变频器应用电路 (5)

2.1 变频器的发展动向及技术指标 (5)

2.1.1 变频器的发展情况 (5)

2.1.2 变频器技术的发展趋势 (7)

2.1.3 变频器的技术指标 (8)

2.2 变频器结构与功能 (9)

2.2.1 变频器主电路结构及功能 (9)

2.2.2 变频器控制电路结构及功能 (15)

2.3 SPWM脉冲生成原理 (17)

3 变频器V/F控制技术 (20)

3.1 V/F控制的原理 (20)

3.2 V/F曲线的选择 (20)

3.3 转速开环的V/F控制方式 (21)

3.4 转速闭环的V/F控制方式 (23)

4 变频器硬件电路设计部分 (25)

4.1 变频器主电路设计 (25)

4.2 变频器控制电路设计 (26)

4.2.1 AT89C51单片机 (26)

4.2.2 SLE4520集成芯片 (27)

4.2.3 通用键盘显示电路 (32)

4.2.4 ADC0809模/数转换芯片与AT89C51的接口 (36)