Current control with asymmetrical regular sampled pulse width modulator applied in parallel active filter

Abstract

Abstract. This paper presents an analysis of the properties of pulse width modulator with a single (symmetrical regular sampled PWM) and double (asymmetrical regular sampled PWM) control sampling of the input signal (low-frequency control input wave) in presence of a triangular auxiliary signal. In this paper, a comparison of the characteristics of these modulators used in the control system with a linear proportional controller is presented. The article provides the relations derived for the maximum amplification of regulators for which the control system operates stably. Analysis results have been confirmed by simulation and experimental studies of a commercial active filter installed in an industrial plant. Simulation studies show an increase of the critical proportional controller gain with symmetrical regular sampled PWM with a doubled number of samples in the period of the triangular auxiliary signal for which the control system is stable. Also, the analysis included in this article demonstrates the possibility of increasing the value of the gain of the proportional controller in a closed system with asymmetrical regular sampled PWM. Publications [8][9][10][11][12][13][14] devoted to applications in power electronics systems with the asymmetrical regular sampled PWM are not related to control systems with a proportional controller. From the point of view of the topics covered in this article, the most interesting paper is publication [15]. This paper addresses the digital control system with asymmetrical regular sampled PWM with different types of controllers, but the issues critical to the gain of the proportional controller addressed in the present article are not discussed.One of the objectives of the work presented is to compare the dynamic and static properties of the control system with a proportional controller and symmetrical regular sampled or asymmetrical regular sampled PWM.Carried out in this article is an analysis taking into account the time between the instant of measurement of the controlled value and the actual determination of the magnitude of the sampled reference (PWM computation delay [15]).Control system with proportional controller has non-zero value of disturbance error. From the point of view of minimizing the disturbance errors and the reducing the time of decay of transient component of this error advantages of asymmetrical regular sampled PWM compared to the symmetrical regular sampled PWM manifest themselves only under the condition of an appropriately small value of the PWM computation delay.The article also describes a mechanism allowing for elimination of the impact of this error on the output current of the APF. This is a feature of APF with supervisory system of DC link voltage which allows the use of output current proportional controller.

Model predictive control of multilevel cascaded converter with boosting capability – a simulation study

“…Classical converter can reach maximum value of modulation index m = 1.15. For parameters used in simulation maximum output phase voltage measured was 100V whilst a classical converter can reach maximum (13) where V 1 is the 1st order harmonic of the output phase voltage. Figure 12 presents waveforms for modulation index m = 2 at phase displacement angle φ = 85.…”

“…This paper is focused on investigation of a novel hybrid converter topology -5-level cascaded H-bridge converter (5LCHB) with only one DC source, controlled with model predictive controller (MPC). The 5LCHB converter with PWM Control Method and fundamental switching scheme were presented in [4,5,[10][11][12][13]. According to [5], 5LCHB topology with a fundamental frequency switching is able to boost output AC voltage.…”

Analysis of Ripple Current in the Capacitors of Active Power Filters

“…The algorithm described in the literature [20,21] is implemented in the control system with a voltage regulator in the dc-circuit. The control block diagram, criteria for selection of the current regulator gain factor, and criteria for determining the inductance L at the outputs of the PAPF (L is the nominal value of L _1 and L _2 ) are presented in [22]. The analysis carried out in this article does not influence the impact of PAPF control methods on the quality of compensation of higher harmonics of non-linear load current.…”

“…Figure 4a,b show carrier waveforms for two PWM techniques: ( Figure 4a) double interleaved PWM carriers [3] and (Figure 4b) double three interleaved PWM carriers [13,22]. The duration time of the microprocessor interruption service routine is denoted by τw (PWM computation delays [22,27]). The choice of the PWM technique is justified by the results of the simulation research collected in Section 6.3.…”

“…Conditions for the type of three-phase harmonic sequence of inverter output voltages. The duration time of the microprocessor interruption service routine is denoted by τ w (PWM computation delays [22,27]). The choice of the PWM technique is justified by the results of the simulation research collected in Section 6.3.…”