单片机题目答P辩PT.pptVIP

剑杆织机经纱张力控制系统设计 答辩人： 罗永全 指导老师：王锦 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 剑杆织机经纱张力控制系统设计的目的就是保持经纱张力的恒稳，采用单片机对其进行控制。本文介绍一种利用AT89C51和SA4828设计电机变频调速的方法，通过控制电机的转速达到对经纱张力的控制。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 变频调速原理 变频调速是改变电动机定子电源的频率，从而改变其同步转速的调速方法。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. SPWM波控制频率 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. SA4828内部结构图由图3.8所示。来自单片机的数据通过总线控制和译码进入初始化寄存器或控制器。他们对相控逻辑电路进行控制。外部时钟输入经分频器分成设定的频率，并生成三角形载波，三角载波与所选定的片内ROM中的调制波形进行比较，自动生成SPWM输出脉冲。 片内ROM存有3种可供选择的波形，它们是纯正弦波形、增强型波形和高效型波形（如图3.10所示）。每种波形各有1536个采样值。增强型波形又称三次谐波，它可以使输出功率提高20%，三相谐波互相抵消，防止电动机发热。高效型波形又称带死区的三次谐波，它是进一步优化的三次谐波，可以减小逆变开关管的损耗，提高功率利用率。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 系统框图 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 1.系统的主体是AT89C51和SA4828，用以产生SPWM波。 2.要控制电动机的转速即通过对前两者编程产生SPWM波来控制电机电源频率 3.其中还需要逆变电路，把交流电变为可控的交流电 4.测速模块，采用8253作为计数器，用来把电动机的转速反馈到单片机并显示 5.键盘输入与液晶显示，用来对电机速度进行调节，显示 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 系统主要模块 单片机AT89C51 变频芯片SA4828 逆变电路 测速模块8253 扩展芯片8255 键盘与显示 Evaluation only. Cre