R.L. Kirlin

Space vector PWM technique with minimum switching losses and a variable pulse rate [for VSI]

A novel randomized control strategy for three-phase voltage source inverters, based on voltage space vectors, is described. An implicit asymmetrical modulating function results in switching losses in the inverter being reduced by about half in comparison with those using the classic space vector pulsewidth PWM method. The pulse rate is varied within individual 60/spl deg/ sectors of the vector plane, so that the power spectra of the output voltage are spread over a wide frequency range and acquire a continuous part. Relevant theoretical analyses, computer simulations and experimental results are presented.

Power spectra of a PWM inverter with randomized pulse position

Random pulse width modulation in static power converters results in the partial transfer of power from the discrete spectrum of the output voltage to the continuous spectrum, with advantageous effects on the operation of the supplied electromechanical systems. In this paper, a random PWM technique with randomized pulse position for three-phase voltage-controlled inverters is analyzed. Closed-form equations for the discrete and continuous power spectra of the line-to-line and line-to-neutral voltages of the inverter have been derived and confirmed by experiments. Presented theory opens the way to numerical optimization of the voltage spectra of randomly modulated inverters. >

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.

Optimization of switching frequencies in the limited-pool random space vector PWM strategy for inverter-fed drives

A space vector PWM technique for inverter fed AC drives which, in contrast with known random modulation methods, is characterized by a very small pool of randomly used switching frequencies, is presented. The limited size of the pool facilitates design of digitally implemented subsystems of the drive, whose settings depend on the length of sampling interval. A method for optimal selection of pool frequencies is described and validated by experimental evidence, including EMI measurements.

Optimization of switching frequencies in the limited-pool random space vector PWM technique for inverter-fed drives

A space vector PWM technique for inverter fed AC drives which, in contrast with known random modulation methods, is characterized by a very small pool of randomly used switching frequencies, is presented. The limited size of the pool facilitates design of digitally implemented linear current control schemes, in which the controller settings depend on the length of sampling interval. A method for optimal selection of pool frequencies is described and validated by experimental evidence, including EMI measurements.

An optimal approach to random pulse width modulation in power inverters

The paper describes an endeavor to optimize the power spectrum of output voltage of a three-phase voltage-source inverter using a novel, random-width, minimum-loss, space vector PWM technique. An original time-domain formulation of the spectral information has been derived. It contains all the necessary details for understanding the mechanisms of general randomization schemes for suppressing harmonics and diverting the harmonic power into the noise spectral density, The gained insights facilitate optimum design of the randomization parameters of any random PWM method and allow comparison among methods.<<ETX>>

Study on spectral analysis and design for DC/DC conversion using random switching rate PWM

We give the formulation of the power spectral density of the randomized pulse width modulation (RPWM) DC/DC converter based on both constant duty cycle and constant pulse width schemes. We analyze the spectral formulas based on the constant duty cycle and develop a means for nulling the power spectral density at one specified frequency and its harmonics. We revert to optimization methods when switching frequency range is subject to practical constraints. Simulation results illustrate the effectiveness of our approach.

Power and power spectral density in PWM inverters with randomized switching frequency

Theoretical and experimental investigation of the impact of randomization of switching frequency in pulse width modulated (PWM) three-phase inverters on the spectra of output voltage is presented. The case of random PWM with a limited set of employed values of switching frequency is analyzed with respect to both the power and power density spectral components. A novel method for accurate prediction of spectra of inverter voltage is introduced and experimentally verified. Experiments were also used to illustrate the important issue of required width of the range of switching frequencies.

Power spectral density analysis of randomly switched pulse width modulation for DC/AC converters

This paper presents a detailed spectral analysis of the random switching frequency PWM technique for control of three-phase inverters. A number of novel results are reported including criteria for the existence of discrete harmonics in the output voltage waveforms, exact expressions for the power carried by these harmonics and an approximate but accurate formula for the continuous density. Furthermore, the theory is generalized to any periodic modulation function. As an example, the third harmonic injection technique is analyzed, and based on extensive comparisons of predicted spectra with measured spectra and as opposed to all earlier investigations of random PWM schemes, the theory is found to be very accurate for both single phase and line-to-line spectra.

Detection, enumeration, and estimation of multiple co-channel signals

Coupled digital phase-locked loops derived from extended Kalman filter theory, have been shown to suppress adjacent and co-channel interferers. This paper addresses their ability to separate co-channel signals. State observability criteria are defined and examined for nonlinear state observations which model phase modulation. These metrics can then be used to address signal separation and tracking behavior of such loops.<<ETX>>