ABSTRACT

Direct-sequence spread-spectrum (DSSS) and frequency-hopping spread-spectrum (FHSS) modulation techniques have been proposed for the operation of three-phase voltage-source rectifiers (VSR) for the mitigation of EMI in AC Grid. For the first time, in the DSSS modulation technique, binary phase shift keying and quadrature phase shift keying (QPSK) techniques have been adopted for the mitigation of electro-magnetic interference (EMI) in three-phase VSR. A cost-effective field programmable gate array (FPGA) has been employed for carrying out these proposed modulation techniques. A VHDL coding for each modulation technique is written in ISE Xilinx, verified by Model-Sim tool and then implemented using FPGA to produce gate pulses for the rectifier. Rather than building a modulator physically, the control logic is implemented using low-cost FPGA, resulting in the cost and size reduction of the control circuit. The modulation techniques recommended in this paper are compared with the traditional sinusoidal pulse width modulation (SPWM). It is shown that the FHSS and QPSK techniques proposed in this paper result in improved power quality and the conducted EMI levels are reduced by 22.1 and 12.4 dBµV, respectively, when compared with SPWM.

摘要

直接序列扩频 (DSSS) 和跳频扩频 (FHSS) 调制技术已被提议用于三相电压源整流器 (VSR) 的运行，以减轻交流电网中的 EMI。在DSSS调制技术中，首次采用二进制相移键控和正交相移键控（QPSK）技术来减轻三相VSR中的电磁干扰（EMI）。已采用经济有效的现场可编程门阵列（FPGA）来执行这些提出的调制技术。每种调制技术的 VHDL 编码均在 ISE Xilinx 中编写，通过 Model-Sim 工具进行验证，然后使用 FPGA 实现，为整流器产生栅极脉冲。控制逻辑不是通过物理方式构建调制器，而是使用低成本 FPGA 实现，从而降低了控制电路的成本和尺寸。本文推荐的调制技术与传统的正弦脉宽调制（SPWM）进行了比较。结果表明，与 SPWM 相比，本文提出的 FHSS 和 QPSK 技术可改善电能质量，并且传导 EMI 水平分别降低 22.1 和 12.4 dBμV。