DC-DC converters work as one of the crucial components in DC microgrid intergraded power systems. In this brief, the robust output voltage regulation problem of DC-DC boost converter system is addressed by using a continuous nonsingular terminal sliding mode control (CTSMC) technique based on finite-time disturbance observer. By integrating the disturbance estimations into the controller design, an improved sliding mode control (SMC) approach is developed to achieve better voltage tracking performance. The proposed control method admits the properties of fast transient responses, strong suppression ability against time-varying disturbances and small steady state oscillations of output voltage. Experimental results in the presence of both load variations and supplied voltage fluctuations are provided to validate the effectiveness of the proposed algorithm.

Continuous Nonsingular Terminal Sliding Mode Control of DC–DC Boost Converters Subject to Time-Varying Disturbances

Cooperative adaptive cruise control (CACC) has a potential to improve traffic throughput, fuel efficiency and vehicle safety. The CACC utilizes onboard sensors and a wireless communication to achieve vehicle stability and string stability of a platoon. The performance of CACC is degraded due to unreliable wireless communication and uncertain dynamics of the vehicle. In this paper, a disturbance observer based sliding mode control is proposed for the control of cooperative adaptive cruise control system. This scheme estimates the uncertainty present in the actuator dynamics and the acceleration of preceding vehicle as a lumped disturbance. The proposed strategy addresses practical issues such as unavailability of preceding vehicle acceleration and range of uncertainty in the vehicle dynamics. The stability of individual vehicles and the string stability of a platoon are derived. The performance of the proposed scheme is verified by considering various traffic scenarios, and it is compared with an existing method.

Robust Control of Cooperative Adaptive Cruise Control in the Absence of Information About Preceding Vehicle Acceleration

Robust control of mismatched buck DC–DC converters by PWM-based sliding mode control schemes

In this brief, a recent result on disturbance observer-based integral sliding mode control of boost dc-dc converters is extended by proposing a state and disturbance observer to estimate inductor current in the presence of an unknown load. The control objective is to track the output voltage under varying load and varying reference voltage. The stability of state and disturbance observer is proved by Kharitonov’s theorem. Extensive simulation and experimentation are carried out to assess the viability of practical implementation of the proposed observer−controller combination.

State and Disturbance Observer-Based Integral Sliding Mode Controlled Boost DC–DC Converters

With the photovoltaic (PV) penetration increases in dc microgrid, the traditional PV converters with maximum power point tracking (MPPT) control, which are equivalent to current sources, can hardly meet the needs of coordinated operation. The PV converter should operate in both MPPT and constant voltage control (CVC) modes. When the operation mode changes, the PV converter needs to switch between current and voltage sources. Inevitably, the bus voltage instability would be caused. This paper presents a novel switching strategy for the smooth and seamless operation of the PV converter between MPPT and CVC modes. The PV converter under these two modes is always controlled as a voltage source, and its control variables are both the output voltage of PV arrays. When its operation mode changes from MPPT to CVC, a small offset signal based on DC bus voltage would be introduced to the reference voltage of inner loop of the PV converter, so as to shift the maximum power point (MPP) voltage. Meanwhile in the voltage inner loop, a double integral sliding mode controller (DISMC) is used to improve the performance and anti-interference ability of the PV converter. This method unifies MPPT and bus voltage adjustment strategy without any communication and changing any hardware structure and control parameters. When mode switching occurs, only the reference value of voltage inner loop would be slightly adjusted near the maximum photovoltaic power point, so the seamless transition for PV converter between the two modes can be ensured. Finally, the effectiveness of the mode seamless switching control strategy is demonstrated by the simulation and experimental tests.

A novel control strategy for mode seamless switching of PV converter in DC microgrid based on double integral sliding mode control.

This brief proposes a control strategy to regulate nonminimum phase dc–dc converters affected by line and load uncertainties. The objective of regulating the output voltage in the presence of uncertainties in input voltage and load is met by proposing an integral sliding mode control (ISMC) combined with a disturbance observer. The ability of the controller in tracking the reference voltage and regulation of the output voltage is analyzed. The controller is validated experimentally and compared with another scheme based on ISMC.

Regulation of Nonminimum Phase DC–DC Converters Using Integral Sliding Mode Control Combined With a Disturbance Observer

The purpose of this paper is to comment on the reference voltage tracking ability of a recently proposed state observer based adaptive sliding mode control for boost converters. It is shown that the control in the cited paper cannot track the reference voltage. A modified control law that enables reference voltage tracking while preserving the other advantages of the commented paper is proposed and validated by simulation and experimentation on laboratory hardware.

Comment on “PWM-Based Adaptive Sliding-Mode Control for Boost DC–DC Converters”

The aim of this paper is to compare performances of brushless DC (BLDC) motor on two different inverter control strategies. Sinusoidal and square wave are individually applied to the motor and characteristics are studied. A prototype inverter fed BLDC motor drive is designed and developed. DSP dsPIC30F3011 along with MPLAB IDE software is used for generation of firing pulses for each type of inverter control strategy. The drive is tested first on square wave inverter fed supply and then on state vector modulation (SVM) inverter fed supply. The proposed control strategies are simulated in MATLAB/Simulink and simulation results are validated with hardware. Experimental and simulated results are also compared for performances of complete BLDC motor drive.

Sanjeev Kumar Pandey

Papers

Robust control of mismatched buck DC–DC converters by PWM-based sliding mode control schemes

Regulation of Nonminimum Phase DC–DC Converters Using Integral Sliding Mode Control Combined With a Disturbance Observer

State and Disturbance Observer-Based Integral Sliding Mode Controlled Boost DC–DC Converters

Comment on “PWM-Based Adaptive Sliding-Mode Control for Boost DC–DC Converters”

Performance analysis of BLDC motor on sinusoidal and square wave supply