Control in Power Electronics : selected problems

The conventional grid-connected photovoltaic (PV) inverter is controlled by a dual-loop control strategy in synchronous reference frame, and the controllers are designed for steady-state operating point based on the small signal model by neglecting the high-order and coupling terms. However, in an LCL filter, the coupling terms are complicated due to the dq transformation which will affect the dynamic performance. In this paper, an innovative simplified feedback linearization (SFL) control strategy is proposed for the PV inverter with the LCL filter, which offers satisfactory performance, particularly, in decoupling the control system, improving the dynamic performance, and enhancing the adaptability. Furthermore, the SFL controllers are simpler than the high-order tracking controllers used in conventional feedback linearization control. The detailed simplification process and accurate transfer functions for SFL control strategy have been presented, and the performance comparisons between the proposed SFL control strategy and the classical dual-loop method are carried out to show the characteristics of the proposed control algorithm. Finally, a laboratory prototype of a 150-kW PV inverter with the LCL filter has been implemented to test the feasibility and effectiveness of the proposed strategy. The proposed SFL control strategy can also be applied to a higher order system or other power converters.

Simplified Feedback Linearization Control of Three-Phase Photovoltaic Inverter With an LCL Filter

In this paper, the impacts of various data integrity attacks on the power electronic hardware present in an EV charger are comprehensively analyzed in order to provide necessary recommendations to defend against cyberattacks on electric vehicles and their onboard charging (OBC) systems. The adverse scenarios arising due to cyberattacks are carefully reviewed in this study, which includes (a) interfering with the main charger controller (FPGA) logic and its data, (b) establishing fake communication between the charging controller and other electronic control units (ECUs) connected over same controller area network (CAN) bus, and (c) interfering with the battery management system functionalities. A 6.6kW interleaved totem-pole PFC front-end followed by a high frequency DC-DC converter is used as our OBC representative system in this analysis. Possibilities and ways of potential cyberattacks on this model are investigated in detail. Effort is made towards providing software as well as hardware design-level protection mechanisms to mitigate the malicious effects of such cyberattacks on the OBC hardware. This system is simulated in MATLAB/Simulink to verify the fault occurrences under various data integrity attacks as well as to validate the effectiveness of our proposed countermeasure approaches. Quantitative analyses of the obtained results clearly demonstrate that if adequate precautionary measures are properly taken while designing the charging architecture (e.g., implementing intelligence to the main controller), any electrical hazard or deterioration of health of the components can be avoided to the maximum extent under the circumstances of a malicious cyberattack.

/pdf/cybersecurity-of-onboard-charging-systems-for-electric-3bpxgti75a.pdf

Cybersecurity of Onboard Charging Systems for Electric Vehicles—Review, Challenges and Countermeasures

Disclosed herein is a switched reluctance motor including: a rotor part including a rotor core having a shaft fixedly coupled to the center thereof and a plurality of rotor salient poles formed to be protruded from an outer peripheral surface of the rotor core; a stator part including a stator yoke having the rotor part rotatably received in an inner portion thereof and a plurality of stator salient poles formed to be protruded from the stator yoke in a direction toward the rotor salient poles so as to correspond to the rotor salient poles and having coils wound therearound; and a printed circuit board fixedly coupled to an upper portion of the stator part and including a plurality of through-holes having the coils penetrating therethrough, the coil being wound around the plurality of stator salient poles.

Switched reluctance motor

In this paper a novel unified modelling and control procedure for Back-to-Back converters is introduced. The proposed procedure captures in a single state-space model detailed converter dynamics of both LCL filters and DC-capacitor. A linear multivariable approach has been identified as the most suitable control strategy for taking full advantage of the unified model. A state-feedback controller has been designed for controlling both inverter output currents and DC-bus voltage. It has been shown the main advantage of the proposed modelling procedure is in its detailed knowledge of the existing coupling between the AC currents and the DC-capacitor voltage. As a result, the proposed unified controller takes into account the whole system dynamics in order to maintain the DC-bus voltage nearly constant. The proposed control strategy was experimentally validated by using two 15kVA VSCs (Voltage Sourced Converters) in Back-to-Back configuration. The performance of the unified controller was compared with the performance of the conventional strategy based on the cascade control structure. It was experimentally demonstrated the proposed unified control significantly outperforms the conventional control of DC-bus voltage.

A unified control of back-to-back converter

Control of three - phase voltage source pulse width modulation (PWM) LCL filtered rectifier based on input - output linearization nonlinear control is realized. This control algorithm needs to transformation between a - b - c and d - q coordinates. In this paper, grid connection of rectifier which consists of six IGBT power switches, is provided through LCL filter and sinusoidal pulse width modulation (SPWM) technique which has 9 kHz switching frequency, is used for switching. All simulations are carried out with Matlab/Simulink. By the simulation results, line currents' harmonic distortions, and dc - link voltage and the obtaining of unity power factor are shown under load and reference changes.

Simulation of three - phase voltage source pulse width modulated (PWM) LCL filtered rectifier based on input - output linearization nonlinear control

In this paper, simulations of single — phase power factor corrector (PFC) that has buck-boost circuit topology under input — output linearization nonlinear control with current and voltage control are realized. Buck-boost converter is connected to ac grid by single phase diode bridge rectifier and it works in boundary conduction mode (BCM). For switching of single switched buck-boost converter, compared saw tooth with dc control signal (PWM) technique has been utilized and switching frequency adjusted to 100 kHz. Simulations are carried out with Matlab/Simulink. By the simulations, the effect of PFC buck-boost rectifier on unity power factor, line current harmonic distortion, the sinusoidality of line current and dc — link voltage are presented.

Input-output linearization control of single-phase buck-boost power factor corrector

In this paper, the control of Voltage source converter which consists of six IGBT power switches is realized. Grid connection of VSC is provided through LCL filter and sinusoidal pulse width modulation (SPWM) technique which has 9 kHz switching frequency, is used for switching. Three different way of control including a — b — c, d — q and input — output linearization nonlinear control, are analyzed and achieved with simulations in Matlab/Simulink. The effects of control methods to the grid and dc — link are examined.

Control of LCL filter based voltage source converter

In this paper, simulations of three - phase voltage source rectifier using L and LCL filter under input - output linearization nonlinear control, are realized. The control algorithm requires transformations between a-b-c and d-q frames. A bridge rectifier having six IGBT power switches has been employed. For switching, compared triangular wave sinusoidal pulse width modulation (SPWM) technique has been utilized and switching frequency is adjusted to 9 kHz. Simulations are carried out with Matlab/Simulink. A major advantage of using LCL filter compared with the L filter which is the attenuation of harmonics caused by the PWM rectifier, is showed by the simulations. The feature of attenuation can be achieved only if the LCL filter properly damped, in this paper the damping process is carried out with a resistor connected series to filter capacitor. The effects of using L and LCL filter on unity power factor, line currents harmonic distortions and dc - link voltage are presented by the simulations.

http://ieeexplore.ieee.org/iel5/5637220/5648789/05649290.pdf

Input — Output linearization control of three — Phase voltage source PWM rectifier using L and LCL filter

In this paper speed control of brushless DC motor (BLDC) fed by lithium ion battery and photovoltaic energy using SEPIC MPPT with P&O algorithm is realized. In order to charge and discharge the battery, bidirectional battery charger is used. Besides, control algorithm of the bidirectional battery charger is based on the condition of both state of charge (SOC) of battery and available PV power. Furthermore, the study is realized under the solar irradiation and ambient temperature changes by simulations. Thanks to the simulation, BLDC speed is shown under reference and torque changes. In addition, SOC of battery, PV power, battery power and load power are measured. Simulation results provides the desired response of this study.

Erdal Sehirli

Papers

Simulation of three - phase voltage source pulse width modulated (PWM) LCL filtered rectifier based on input - output linearization nonlinear control

Input-output linearization control of single-phase buck-boost power factor corrector

Control of LCL filter based voltage source converter

Input — Output linearization control of three — Phase voltage source PWM rectifier using L and LCL filter

BLDC Speed Control by Bidirectional Battery Charger with SEPIC MPPT