基于桥臂轮换法PWM新技术的单相中频逆变电源研制

发布时间：2018-06-15 08:18

本文选题：桥臂轮换法SPWM + 单相全桥　；参考：《福州大学》2014年硕士论文

【摘要】：单相全桥逆变电路广泛应用于电池、太阳能等直流电源的逆变输出。目前对单相全桥逆变电路的控制通常采用单极型SPWM方法,即对其中一桥臂固定施加工频方波信号,另一桥臂施加高频PWM波信号,使得两桥臂间输出工频交变的SPWM电压,再经过滤波环节达到正弦波输出。该方法具有算法简单、输出波形好的优点。然而逆变电路工作时IGBT器件将产生开关损耗,引起器件发热。虽然在通常应用中将两个桥臂安装于同一散热片上,使散热片内部有一致的温度变化,但各桥臂的开关频率不同,导致IGBT所产生的开关损耗亦不同,IGBT器件内部结温有很大差异。其中处于高频PWM波控制下的桥臂开关损耗大,结温最高,容易发生擎住效应,对逆变电路的可靠运行产生不利影响,严重时甚至损坏器件。能否找到一种控制方式,保持单相全桥逆变电路单极型SPWM输出波形好的优点的同时,均分其两桥臂的开关损耗来降低原有处于高频开关状态下的桥臂损耗及其结温,达到提升逆变电路可靠性的目的。为此,本文提出一种新型SPWM算法——桥臂轮换法SPWM新技术达到上述目的。桥臂轮换法SPWM新技术控制原理：在前一调制波周期使逆变电路的其中一桥臂为工频方波控制,另一桥臂为高频PWM波控制,在下一调制波周期将两桥臂的控制方式对调,如此周而复始。根据桥臂轮换法SPWM新技术(单极型)控制原理及算法,采用DSP编程实现其SPWM实时计算与控制,并设计与制作了单相全桥逆变电路硬件系统,在该平台上进行负载与温升实验,结果证明了桥臂轮换法SPWM新技术具有均分两桥臂开关损耗的优点；并对两种控制方式下的输出电压波形进行谐波分析；应用Melcosim软件分别计算两种SPWM控制方式下的桥臂开关损耗及IGBT器件内部结温,结果证明了桥臂轮换法SPWM新技术的优越性,即IGBT结温较采用单极型SPWM技术的最高结温有显著降低,从而提升了IGBT工作的可靠性。新技术还保持了单极型SPWM波形好的优点。
[Abstract]:Single-phase full-bridge inverter circuit is widely used in the inverter output of DC power supply such as battery, solar energy and so on. At present, the single-phase full-bridge inverter circuit is usually controlled by single-pole SPWM method, that is, one of the bridge arms is fixed with power frequency square wave signal, the other is the high frequency PWM wave signal, which makes the output of the alternating power frequency SPWM voltage between the two bridge arms. After filtering, sinusoidal wave output is achieved. This method has the advantages of simple algorithm and good output waveform. However, when the inverter circuit works, IGBT device will produce switching loss and cause the device heat. Although the two arms are installed on the same radiator in common applications, the internal temperature of the radiator varies uniformly, but the switching frequency of each arm is different, and the switching loss caused by IGBT is also different from the internal junction temperature of IGBT devices. Under the control of high frequency PWM wave, the switch loss of the bridge arm is large, the junction temperature is the highest, and the holding effect is easy to occur, which has a negative effect on the reliable operation of the inverter circuit, and even damages the device seriously. Can we find a control mode to keep the advantages of good output waveform of single-pole SPWM in single-phase full-bridge inverter circuit, and at the same time, divide equally the switching loss of its two arms so as to reduce the loss and junction temperature of the bridge arm which is in the state of high frequency switch? The purpose of improving the reliability of inverter circuit is achieved. In this paper, a new SPWM algorithm, the bridge arm rotation method, is proposed to achieve the above purpose. The control principle of the new SPWM technique of the bridge arm rotation method: one of the arms of the inverter circuit is controlled by the power frequency square wave in the previous modulation wave period, the other is controlled by the high frequency PWM wave, and the control mode of the two arms is changed in the next modulation wave cycle. So round over and over again. According to the control principle and algorithm of single pole SPWM, the SPWM real-time calculation and control are realized by DSP programming. The hardware system of single-phase full-bridge inverter circuit is designed and fabricated, and the load and temperature rise experiments are carried out on the platform. The results show that the new SPWM technique has the advantages of equally dividing the switching loss of the two arms, and the harmonic analysis of the output voltage waveform is carried out under the two control modes. The switching loss of the bridge arm and the internal junction temperature of IGBT devices are calculated by using Melcosim software, respectively. The results show that the new SPWM technology of the bridge arm rotation method has the advantages, that is, the IGBT junction temperature is significantly lower than the highest junction temperature of the monopole SPWM technology. Thus, the reliability of IGBT work is improved. The new technique also maintains the advantage of unipolar SPWM waveform.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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