逆变器死区效应与补偿方法的研究

发布时间：2018-10-12 09:33

【摘要】：现代电力电子技术的飞速发展，极大地促进了交流驱动技术的进步，伴随着各种脉宽调制技术的出现，许多问题也日渐凸显。由于逆变器主电路中的功率开关元件不是理想开关，为了防止同一上下功率管发生直通现象，必须在其驱动信号中设置一段死区时间。虽然死区时间很短，但是对于开关频率较高的系统，死区时间将使逆变器输出电压电流波形发生很大畸变，进而影响系统控制性能，，甚至导致系统不稳定。因此为了改善死区效应对逆变器性能带来的影响，减少输出波形中的谐波成分成为逆变器应用研究的一个重要技术问题，有着实际的工业应用意义。本文首先分析了逆变器加入死区时间带来的死区效应，该效应导致输出电压相位变化，低次谐波增加，并且在零电流区域发生零电流钳位现象。进行了死区电压的傅里叶分析，验证了死区电压平均化考虑的合理性。针对不同调制方式下对死区效应的影响进行了理论分析并通过仿真验证了单极性调制方式下输出电流波形影响相对较小。将现有的主要死区补偿方法分为三类加以论述，即脉冲宽度直接调整法、平均电压补偿法和无效开关死区消除方法。通过仿真发现三种方法对死区效应都有一定的抑制作用。在分析传统逆变器死区补偿方法仿真结果的基础上，对各类方法适用于逆变器控制系统的情况进行了比较与讨论，并指出补偿方法上的应用特点与改进方向。在传统无效开关死区消除方法的基础上，提出了一种改进型的无效开关死区消除电路，该电路通过反并联二极管导通检测方法完成了输出电流过零区域的划分，改善了死区效应带来的影响。相比于传统的无效开关消除死区法，该方法既不影响逆变器在过零区域外输出的动态性能，又延长功率管的使用寿命。更重要的是，能够较为精确的划分电流过零区域，更好地解决了死区效应带来的影响。最后，研制了基于dsPIC30F4011单片机的单相逆变控制系统实验平台，详细介绍了实验平台硬件和软件设计。在该平台上进行了改进型无效开关死区消除电路调试。实验结果表明系统输出电流波形较补偿前有很大的改善，验证了该电路的有效性。
[Abstract]:The rapid development of modern power electronics technology has greatly promoted the progress of AC driving technology. Along with the emergence of various pulse width modulation technology, many problems have become increasingly prominent. Since the power switch element in the main circuit of the inverter is not an ideal switch, a dead time must be set in the driving signal in order to prevent the straight through of the same up-and-down power transistor. Although the dead-time is very short, for the system with high switching frequency, the dead-time will make the output voltage and current waveform of the inverter distorted greatly, which will affect the control performance of the system and even lead to the instability of the system. Therefore, in order to improve the effect of dead-time effect on the inverter performance, reducing the harmonic components in the output waveform has become an important technical problem in the inverter application research, which has practical industrial application significance. In this paper, the dead-time effect caused by adding dead time to inverter is analyzed, which results in the phase change of output voltage, the increase of low order harmonics and the occurrence of zero current clamping in the zero current region. Fourier analysis of dead-zone voltage is carried out to verify the rationality of the consideration of dead-zone voltage averaging. The influence of different modulation modes on the dead-time effect is theoretically analyzed and the simulation results show that the output current waveform under unipolar modulation mode is relatively small. The main dead-time compensation methods are divided into three categories: pulse width direct adjustment method, average voltage compensation method and dead zone elimination method of invalid switch. The simulation results show that the three methods can inhibit the dead zone effect to some extent. On the basis of analyzing the simulation results of traditional inverter dead-time compensation methods, the paper compares and discusses the application of various methods to inverter control system, and points out the application characteristics and improvement direction of compensation methods. Based on the traditional dead zone elimination method of invalid switch, an improved dead zone elimination circuit for invalid switch is proposed. The circuit divides the zero crossing region of output current by the method of reverse parallel diode conduction detection. The dead zone effect is improved. Compared with the traditional dead-time elimination method, this method does not affect the dynamic performance of the inverter output outside the zero-crossing area, but also prolongs the service life of the power transistor. More importantly, the zero-crossing area of current can be divided more accurately, which can better solve the effect of dead zone effect. Finally, the experimental platform of single-phase inverter control system based on dsPIC30F4011 microcontroller is developed, and the hardware and software design of the experimental platform is introduced in detail. The dead time elimination circuit of the improved invalid switch is debugged on the platform. The experimental results show that the output current waveform of the system is much better than that before compensation, and the validity of the circuit is verified.
【学位授予单位】：上海大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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