Analysis, modeling, design and implementation of average current mode control for interleaved boost converter

Abstract: In this paper, a simple novel control strategy is designed and analyzed for a hybrid energy storage system (HESS). In the proposed method, batteries are used to balance the slow changing power surges, whereas supercapacitors (SC) are used to balance the fast changing power surges. The main advantage of the proposed control strategy is that, the slow response of battery system including dynamics of battery, controller, and converter operation, is overcome by diverting the power surges to the SC system. The proposed method inherits charge/discharge rate control to improve the life span and reduce the current stresses on battery. The proposed method features less computational burden as it uses simple control strategy. The detailed experimental results presented validate the proposed control strategy for sudden changes in photovoltaic (PV) generation and load demand.

Abstract: The power generation from renewable power sources is variable in nature, and may contain unacceptable fluctuations in case of the wind power generation. High fluctuations in power generation may negatively impact the voltage stability of the microgrid. This problem can be alleviated by using hybrid energy storage system consisting of batteries and supercapacitors (SCs) at dc grid. A new control scheme is proposed to control the power sharing between batteries and SCs to match the generation-demand mismatch and hence to regulate the grid voltage. In the proposed control strategy, the SC supplies error component of the battery current in addition to the fast transient power demand. This added feature not only improves the dc grid voltage regulation capability but also reduces the stress levels on the battery and hence increases the life span of the battery. The main advantage of the scheme is that, the uncompensated power due to slow dynamics of the battery is diverted to the SC and keeps the state of charge within the limits for longer duration, as compared to the conventional strategy. The proposed scheme is validated through detailed experimental studies.

Abstract: For interleaved boost-type converters, both functions of voltage regulation and current balance are important. In this paper, the decoupled current-balancing control (DCBC) with two parallel loops is proposed. At first, the small-signal transfer functions of the voltage-regulation loop and the current balancing loop to the controller output are derived. The results show that the voltage-regulation loop and the proposed current-balancing loop are nominally decoupled. That is, two PI-type controllers can be designed independently and included to implement the proposed DCBC. Additionally, the single-sensor sampling-current strategy is proposed to obtain two average inductor currents by sensing only the sum of diode currents. All the controllers are implemented in field-programmable gate array (FPGA). The provided simulation and experimental results demonstrate the proposed DCBC.

Abstract: Fuel cells have received considerable attention as one of the most promising candidates for green power sources in vehicles. The voltages of fuel cells vary widely depending on the operating conditions. Furthermore, the output power of the fuel cell in a vehicular powertrain should be controlled in accordance with some energy management strategies. For these reasons, the fuel cell must be interfaced with other components by means of a DC/DC converter in fuel cell vehicle applications. A step-up/step-down converter for fuel cell vehicle applications, which effectively operates in step-up or step-down mode when the fuel cell voltage is lower or higher than the output voltage of high-voltage direct current bus, is proposed in this paper. To reduce the current ripple, the interleaved circuit structure is used for the proposed converter. The proportional-integral regulator for the fuel cell current control is achieved by a digital signal processor to improve the reliability and flexibility of the converter. Smooth transition between step-up and step-down modes is realized using average current method for the converter. The principle of operation and theoretical analysis of the converter are given. Experimental results of a prototype are provided to evaluate the performance of the proposed scheme.

Abstract: In this paper, a two-stage power-electronics topology is presented for use in a BIPV module-level converter, connected to a low-voltage DC microgrid. The converter is built up as a cascade of two topologies, being an interleaved boost converter and a phase-shifted full bridge. The interleaved boost converter was chosen to lower the current stresses for the components and to reduce the required input and output capacitance due to the ripple current cancellation in the in- and output. The full bridge is chosen for its galvanic isolation and to perform the high step-up via the transformer turns ratio. It is shown that the maximum intermediate voltage level in between both converters can be derived from the continuous conduction mode of operation. Simulations are provided that show the correct operation of the overall structure. An experimental prototype has been built to demonstrate the overall performance of the converter.

Abstract: Preface. 1. Introduction. I: Converters in Equilibrium. 2. Principles of Steady State Converter Analysis. 3. Steady-State Equivalent Circuit Modeling, Losses, and Efficiency. 4. Switch Realization. 5. The Discontinuous Conduction Mode. 6. Converter Circuits. II: Converter Dynamics and Control. 7. AC Equivalent Circuit Modeling. 8. Converter Transfer Functions. 9. Controller Design. 10. Input Filter Design. 11. AC and DC Equivalent Circuit Modeling of the Discontinuous Conduction Mode. 12. Current Programmed Control. III: Magnetics. 13. Basic Magnetics Theory. 14. Inductor Design. 15. Transformer Design. IV: Modern Rectifiers and Power System Harmonics. 16. Power and Harmonics in Nonsinusoidal Systems. 17. Line-Commutated Rectifiers. 18. Pulse-Width Modulated Rectifiers. V: Resonant Converters. 19. Resonant Conversion. 20. Soft Switching. Appendices: A. RMS Values of Commonly-Observed Converter Waveforms. B. Simulation of Converters. C. Middlebrook's Extra Element Theorem. D. Magnetics Design Tables. Index.

Abstract: Current mode control as usually implemented in switching power supplies actually senses and controls peak inductor current. This gives rise to many serious problems, including poor noise immunity, a need for slope compensation, and peak-to-average current errors which the inherently low current loop gain cannot correct. Average current mode control eliminates these problems and may be used effectively to control currents other than inductor current, allowing a much broader range of topological application.

Abstract: A recently proposed average current-mode control method is analyzed. A complete small-signal model for the control scheme is developed. The model is accurate up to half the switching frequency. This control scheme is suitable for applications where the average inductor current needs to be controlled, as in power factor correction circuits and battery charger dischargers. The subharmonic oscillation, commonly found in peak current-mode control, also exists in this method. This subharmonic oscillation can be eliminated by properly choosing the proper gain of the compensation network in the current loop. Model predictions are confirmed experimentally. >

Abstract: Multiphase converter topologies for use in high-performance applications have received increasing interest in recent years. This paper proposes a novel multidevice interleaved boost converter (MDIBC) that interfaces the fuel cell with the powertrain of hybrid electric vehicles. In this research, a multidevice structure with interleaved control is proposed to reduce the input current ripples, the output voltage ripples, and the size of passive components with high efficiency compared with the other topologies. In addition, low EMI and low stress in the switches are expected. The proposed dc/dc converter is compared to other converter topologies such as conventional boost converter (BC), multidevice boost converter (MDBC), and two-phase interleaved boost converter (IBC) to verify its dynamic performance. Furthermore, a generalized small-signal model is derived for these dc/dc converters, which has not been previously discussed. A digital dual-loop control is designed to achieve the proper regulator for the converters with fast transient response. The dc/dc converter topologies and their controller are designed and investigated by using MATLAB/Simulink. Finally, the proposed converter (MDIBC) is experimentally validated with results obtained from a 30-kW prototype that has been built and tested in our laboratory based on TMS320F2808 DSP. The simulation and experimental results have demonstrated that the proposed converter is more efficient than other dc/dc converter topologies in achieving high performance and reliability for high-power dc/dc converters.

Abstract: This paper addresses modeling and practical design issues for PWM converters with average current control. A straight-forward averaged modeling method is proposed, and the resulting models are shown to be accurate enough for practical design purpose. Limitations of previously published models that incorporate sampling effect are discussed. The proposed averaged model is then applied for stability analysis and control design. In particular, conditions under which switching instability may occur are identified, and design method that avoids the instability problem is presented. The proposed modeling and design methods are demonstrated and further validated by a prototype synchronous-switch buck converter with 5 V input and 2 V output.