Analysis of power and power spectral density in PWM inverters with randomized switching frequency

A novel method for accurate calculation of power spectra of the pulsewidth modulation (PWM) voltage-source inverter with randomized switching frequency is presented. The case of a limited pool of switching frequencies, convenient and adequate for technical purposes, is considered, and a mathematical background for this type of random PWM (RPWM) is provided. It is shown that the limited-pool RPWM gives rise to not only a continuous spectrum, but, also, under certain circumstances, pure power spectral components (harmonics), typical for the deterministic PWM. Criteria for the existence of harmonics are given, and formulae for both the power and the power spectral density are derived and verified experimentally.

[1]  R. L. Kirlin,et al.  Power spectra of a PWM inverter with randomized pulse position , 1993 .

[2]  Frede Blaabjerg,et al.  Random modulation techniques with fixed switching frequency for three-phase power converters , 1999, 30th Annual IEEE Power Electronics Specialists Conference. Record. (Cat. No.99CH36321).

[3]  Gordon MacGregor Russell,et al.  Modulation and coding in information systems , 1962 .

[4]  S. Bolognani,et al.  Reduction of the electromagnetic interference conducted to mains in inverter-fed AC drives using random pulse width modulation , 1998, Conference Record of 1998 IEEE Industry Applications Conference. Thirty-Third IAS Annual Meeting (Cat. No.98CH36242).

[5]  A. Trzynadlowski,et al.  An overview of modern PWM techniques for three-phase, voltage-controlled, voltage-source inverters , 1996, Proceedings of IEEE International Symposium on Industrial Electronics.

[6]  C.M. Penalver,et al.  Improving pulse width modulation in order to get a silent AC motor , 1997, ISIE '97 Proceeding of the IEEE International Symposium on Industrial Electronics.

[7]  T. Habetler,et al.  Acoustic noise reduction in sinusoidal PWM drives using a randomly modulated carrier , 1989 .

[8]  D. W. Tufts,et al.  Statistical Communication Theory , 1958 .

[9]  Thomas G. Habetler,et al.  Angle controlled current regulated rectifiers for AC/AC converters , 1989 .

[10]  Irene A. Stegun,et al.  Handbook of Mathematical Functions. , 1966 .

[11]  J. T. Boys,et al.  Noise quieting with random PWM AC drives , 1998 .

[12]  D. Middleton.  An Introduction to Statistical Communication Theory , 1960 .

[13]  Frede Blaabjerg,et al.  Experimental evaluation of modern random PWM techniques for induction motor drives , 1997, 1997 IEEE International Electric Machines and Drives Conference Record.

[14]  Frede Blaabjerg,et al.  Optimization of switching frequencies in the limited-pool random space vector PWM technique for inverter-fed drives , 1999, APEC '99. Fourteenth Annual Applied Power Electronics Conference and Exposition. 1999 Conference Proceedings (Cat. No.99CH36285).