摘要
该文提出一种基于 CPLD(复杂可编程逻辑器件)、由全数字化方法实现自然采样法的 SPWM(正弦脉宽调制)新方案。该方案同时具有数字电路稳定可靠便于集成、微处理器可以重复编程、以及自然采样法响应快精度高等优点。对正弦调制信号 us(t)的数字化处理,会引起 SPWM 输出脉冲宽度的误差。当 us(t)斜率为正时输出负脉冲变宽;us(t)的斜率为负时输出正脉冲变宽;这相当于在输出基波上附加了一个齐次谐波分量。SPWM 数字化自然采样法存在脉冲竞争现象。研究表明最大误差脉冲宽度和竞争脉冲宽度均与模数转换的采样周期和调制深度成正比,与载波比成反比;竞争脉冲的个数由 us(t)的斜率决定。给出了消除竞争脉冲的方法。在一台 4kVA 单相 SPWM 电压型并联四重化逆变器上取得了满意的实验结果。
A novel scheme of digital natural sampling based SPWM (sinusoidal PWM) is presented which is achieved by CPLD (complex programming logic device). This scheme is trusty and easily integrated as digital circuit, programmable as microprocessor, and rapid in response and with a precision as natural sampling SPWM. The digitization of sinusoidal modulation signals us(t) however, may cause a pulse width error in the SPWM output. A positive slope of us(t) makes the plus pulse width wider, and a negative one makes the minus pulse width wider. All these errors can be equivalent to adding an odd harmonic to the fundamental. There are some pulse competition in the digital natural sampling based SPWM. The study inchcates that the best error pulse width and the competition pulse width are proportional to the sampling period to us(t) and the modulation degree of SPWM; the number of competition pulse are dependent on the slop of us(t). A method for eliminating the competition pulses is presented. Satisfactory experiment results were obtained in a single-phase 4kVA voltage source inverter operating in 4-multiple SPWM.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2005年第1期32-37,共6页
Proceedings of the CSEE
基金
陕西省教育厅重点科研资助项目(99JK160)。
