Reducing Beat Frequency Oscillation in a Two-phase Sliding Mode-controlled Voltage Regulator Module

During static and dynamic loading conditions, voltage regulator modules (VRMs) are expected to provide regulated voltage with minimal ripple even at high current requirement.  Compared to regular power supplies, VRMs repetitively experience high-frequency loading conditions that is greatly dependent on the software running in the processor utilizing them. In the scenario that when the transient load frequency is near the VRM’s switching frequency, high-magnitude and low-frequency oscillations are observed at the phase currents.  This phenomenon is called the beat frequency oscillation.  In this study, the sliding mode control principle is employed to both the voltage and current share loops of the VRM to reduce the phase currents’ beat frequency oscillations. A fixed frequency sliding mode controller is derived and extensively evaluated using the PSIM simulator.  Our results show that while maintaining equal load sharing among VRMs at less than 5% sharing error and various types of loading conditions, the sliding mode controller can reduce the beat frequency oscillation phenomenon to 20 kHz at maximum with reduced peak current values.   The output voltage is also regulated within the desired ±1.65% band

Predicting Converter Utilization Convergence under Various Dynamic Loading Conditions of Paralleled Converters

Abstract-In this paper, converter utilization equalization under various dynamic loading conditions experienced by parallel buck converters were observed. Equalization of converter utilization is ensured by using fuzzy logic control while output voltage regulation and current sharing between converters is maintained by employing sliding mode control. This research work has also contributed the derivation of the working equation in determining the converter's utilization point of equalization even in dynamic loading. Simulation results have confirmed that the value solved from the working equations are correct and equal to the value of the utilizations each of the converters converged under a given dynamic load

Reducing beat frequency oscillation in a two-phase sliding mode-controlled voltage regulator module

During static and dynamic loading conditions, voltage regulator modules (VRMs) are expected to provide regulated voltage with minimal ripple even at high current requirement. Compared to regular power supplies, VRMs repetitively experience high-frequency loading conditions that is greatly dependent on the software running in the processor utilizing them. In the scenario that when the transient load frequency is near the VRM’s switching frequency, high-magnitude and low-frequency oscillations are observed at the phase currents. This phenomenon is called the beat frequency oscillation. In this study, the sliding mode control principle is employed to both the voltage and current share loops of the VRM to reduce the phase currents’ beat frequency oscillations. A fixed frequency sliding mode controller is derived and extensively evaluated using the PSIM simulator. Our results show that while maintaining equal load sharing among VRMs at less than 5% sharing error and various types of loading conditions, the sliding mode controller can reduce the beat frequency oscillation phenomenon to 20 kHz at maximum with reduced peak current values. The output voltage is also regulated within the desired ±1.65% band. © 2019 Institute of Advanced Engineering and Science. All rights reserved

Speed and torque control of a DC shunt motor

This paper discusses the speed and torque control of a shunt DC motor through MATLAB Simulink simulations. The DC shunt motor is 120Vdc with rated speed of 1800 revolutions per minute. Blocks pertinent to the control of the DC motor are modeled using basic blocks found in the Simulink library

Implementation of sliding mode control for current sharing in fixed frequency voltage regulator modules

Voltage regulator modules (VRMs) have to maintain perfect current sharing between modules in both static and dynamic loading. In this study, sliding mode control was applied to both the voltage loop and the current share loop of the two-phase VRM with the aim of providing an effective current sharing scheme. Unlike other sliding mode control implementation that uses infinite switching frequency in its control method, fixed switching frequency was used. Derivation for the fixed frequency sliding mode control was done in the analog domain and transformed into the digital domain. A simulation model using PSIM was developed for both the analog and the digital control implementations. Results show that current sharing is achieved in both the analog and the digital control