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Analysis and Controller Design of a Universal Bidirectional DC-DC Converter
Energies
Abstract and Figures
In this paper, first the operating principles of a non-isolated universal bidirectional DC-DC converter are studied and analyzed. The presented power converter is capable of operating in all power transferring directions in buck/boost modes. Zero voltage switching can be achieved for all the power switches through proper modulation strategy design, therefore, the presented converter can achieve high efficiency. To further improve the efficiency, the relationship between the phase-shift angle and the overall system efficiency is analyzed in detail, an adaptive phase-shift (APS) control method which determines the phase-shift value between gating signals according to the load level is then proposed. As the modulation strategy is a software-based solution, there is no requirement for additional circuits, therefore, it can be implemented easily and instability and noise susceptibility problems can be reduced. To validate the correctness and the effectiveness of the proposed method, a 300 W prototyping circuit is implemented and tested. A low cost dsPIC33FJ16GS502 digital signal controller is adopted in this paper to realize the power flow control, DC-bus voltage regulation and APS control. According to the experimental results, a 12.2% efficiency improvement at light load and 4.0% efficiency improvement at half load can be achieved.
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... Ultimately, designing a hardware system for digital control of a step-up DC/DC converter requires extensive knowledge of power electronics, microcontrollers, and control algorithms. Successful implementation of such a project involves careful planning, simulation and prototyping of all system components [9,10]. ...
... In Equation 1 below, we can see the output voltage. This voltage can be utilized after a DC-DC converter [29]. ...
The necessity for permanent use of electrical and electronic devices has generated a greater demand for electricity along with more efficient transmission techniques. Energy from the environment can be radio frequency (RF) signals, friction, solar, thermal, or vibration. The increase in autonomous energy devices and sensors depends on the evolution of Energy Harvesting (EH) techniques. In recent years, many self-developed energy devices have been deployed in various types of systems. With the continuous progress of technology, such autonomous devices accomplish more and more challenging operations (e.g., in agriculture or health care), which can be manufactured by consuming only a few uW or even more pW of power. The capacity to function with minimal power consumption is very important in modern electronics design. We present a rectifier circuit for radio frequency (RF) energy harvesting systems that works at 5 and 5.8 GHz. The proposed circuit provides a high PCE (power conversion efficiency) of 64.56% for an input power equal to 10 dBm.
... In the experimental model, the bidirectional buck-boost dc/dc converter has been used ( Figure 4). The implemented DC/DC converter and control methods are well known and are widely described in the literature [30,31]. Depending on the method of controlling the switches (S1 −-S4), the converter enables bidirectional energy flow (from side A to B or from B to A) and control of the output voltage value. ...
This study describes a laboratory model of a battery energy storage system (BESS) designed for testing algorithms aimed at reducing peak power consumption in railway traction substations. The system comprises a DC/DC converter and battery energy storage. This article details a laboratory model of a bidirectional buck-boost DC/DC converter, which is used to transfer energy between the battery energy storage and a DC line. It presents an analysis of DC/DC converter systems along with simulation studies. Furthermore, the results of laboratory tests on the DC/DC converter model are also provided. The control algorithm of the system in the traction substation is focused on reducing peak power, offering benefits such as lower charges for the railway operator due to the possibility of reducing contracted power requirements. From the perspective of the power grid, the reduction in power fluctuations and, consequently, voltage sags, is advantageous. This paper includes a description of a hardware simulator for verifying the system’s control algorithms. The verification of the control algorithms was performed through experimental tests conducted on a laboratory model (a hardware simulator) of the system for dynamic load reduction in traction substations, on a power scale of 1:1000 (5.5 kW). The experimental tests on the laboratory model (hardware simulator) demonstrated the effectiveness of the algorithm in reducing the peak power drawn from the power source.
... This is a four-quadrant converter, so it can operate in buck and boost modes in both directions [105,106]. The switches have lower electrical and thermal stresses than traditional buck-boost converters and can achieve ZVS without the use of an additional or auxiliary soft switching circuit by employing appropriate modulation strategies [107]. It does, however, have complex control strategies and suffers from some turn-on losses due to the reverse recovery problem of transistor body diodes when the conventional PWM strategy is used while operating in CCM, which reduces efficiency [108]. ...
The penetration of electric vehicles is becoming more and more widespread and recently electric buses and trains are fetching the attention of researchers and developers. In this review, we examine the charging systems applied to the fast charging of electric vehicles and buses as well as the charging strategies, mainly applied to electric buses. We also briefly delve into power topologies for a more electrified railway system where we discuss their different supply systems as well as their motor drive systems. Problems and charge challenges for electric buses and trains are discussed too.
... Where R , L F , C F are represented as the transfer resistance, inductor and capacitor of circuit for battery. S is the switching factor between buck and boost mode of DC-DC converter [11], [12]. The switching factor can be modified as the element of the system matrix as equation 2. ...
Background/Objectives: The power performance of electric vehicle chargers depends on the control efficiency of the power converters with on-board and off-board types. In this paper, a new control method is proposed for power converter of fast electric vehicle chargers in order to improve the power efficiency.Methods/Statistical analysis: The proposed control method is the optimal control to minimize the performance objectives from the predicted output, based on the system model. The discretized model of DC-DC converter with sampling time is derived by using lifting operation for taking into account with the desired prediction time.Findings: The existing conventional controllers are obtained by off-line optimal solution and applied to the systems. Once the control gain is determined, the controller is able to reflect the system response at the real-time.Improvements/Applications: The proposed control method has advantages to deal with system performances at real-time and the control actuation is updated every sampling time via the derived mathematical model. It can be directly applicable to real electric vehicle charger systems in industry.
A green hybrid electric scooter (HES) with a proton exchange membrane fuel cell (FC) as the primary energy storage system (ESS) and a lithium-ion battery (LIB) as the other assistant ESS is developed in this study. A hierarchical power management system is proposed to control the power flows of dual ESSs within the HES to achieve preferable energy utilization efficiency. A rule-based control strategy is first designed in the upper power optimization layer. Subsequently, a global search algorithm and a Cuckoo search algorithm (CSA), which both consider the information including the state-of-charge of LIB, total demanded power of the HES, and efficiencies of the FC, LIB, and power converters, are proposed for optimizing a power split ratio parameter, thereby ensuring optimal power allocation for the HES. In the middle power allocation layer, the current commands of both DC-DC converters connected to the ESS are individually determined. Finally, semi and fully-active hybrid powertrains with voltage and current control loops are designed in the lower power control layer to regulate the practical drive currents and the DC bus voltage. Results demonstrate that the HES can obtain promising endurance and speed tracking performances by using the proposed fully active hybrid powertrain with the CSA strategy.
Stand-alone power systems based on renewable energy sources are used to replace generators based on fossil fuels. Those renewable power systems also require Energy Storage Devices (ESD) interfaced by a charger/discharger power converter, which consist of a bidirectional DC/DC converter, and a DC bus. This paper proposes a single sliding-mode controller (SMC) for the charger/discharger DC/DC converter to provide a stable DC bus voltage in any operation condition: charging or discharging the ESD, or even without any power exchange between the ESD and the DC bus. Due to the non-linear nature of the power converter, the SMC parameters are adapted on-line to ensure global stability in any operation condition. Such stability of the adaptive SMC is mathematically demonstrated using analytical expressions for the transversality, reachability and equivalent control conditions. Moreover, a design procedure for the adaptive SMC parameters is provided in order to ensure the dynamic response required for the correct operation of the load. Finally, simulations and experimental tests validate the proposed controller and design procedure.
This paper proposed a optimal strategy for coordinated operation of electric vehicles (EVs) charging and discharging with wind-thermal system. By aggregating a large number of EVs, the huge total battery capacity is sufficient to stabilize the disturbance of the transmission grid. Hence, a dynamic environmental dispatch model which coordinates a cluster of charging and discharging controllable EV units with wind farms and thermal plants is proposed. A multi-objective particle swarm optimization (MOPSO) algorithm and a fuzzy decision maker are put forward for the simultaneous optimization of grid operating cost, CO2 emissions, wind curtailment, and EV users' cost. Simulations are done in a 30 node system containing three traditional thermal plants, two carbon capture and storage (CCS) thermal plants, two wind farms, and six EV aggregations. Contrast of strategies under different EV charging/discharging price is also discussed. The results are presented to prove the effectiveness of the proposed strategy.
Three-port isolated (TPI) bidirectional DC/DC converters have three energy ports and offer advantages of large voltage gain, galvanic isolation ability and high power density. For this reason this kind of converters are suitable to connect different energy sources and loads in electric and hybrid vehicles. The purpose of this paper is to propose chaotic modulation and the related control scheme for TPI bidirectional DC/DC converters, in such a way that the switching harmonic peaks can be suppressed in spectrum and the conducted electromagnetic interference (EMI) is reduced. Two chaotic modulation strategies, namely the continuously chaotic modulation and the discretely chaotic modulation are presented. These two chaotic modulation strategies are applied for TPI bidirectional DC/DC converters with shifted-phase angle based control and phase-shifted PWM control. Both simulation and experiments are given to verify the validity of the proposed chaotic modulation-based control schemes.
This paper presents a microgrid (MG) energy management strategy by considering renewable energy and battery storage systems. Renewable energy, including wind power generation and solar power generation, is integrated into the distribution network, for which is formulated the optimal dispatch model of mixed-power generation by considering the charging/discharging scheduling of battery storage systems. The MG system has an electrical link for power exchange between the MG and the utility during different hours of the day. Based on the time-of-use (TOU) and all technical constraints, an enhanced bee colony optimization (EBCO) is proposed to solve the daily economic dispatch of MG systems. In the EBCO procedure, the self-adaption repulsion factor is embedded in the bee swarm of the BCO in order to improve the behavior patterns of each bee swarm and increase its search efficiency and accuracy in high dimensions. Different modifications in moving patterns of EBCO are proposed to search the feasible space more effectively. EBCO is used for economic energy management of grid-connected and stand-alone scenarios, and the results are compared to those in previous algorithms. In either grid-connected or stand-alone scenarios, an optimal MG scheduling dispatch is achieved using micro-turbines, renewable energy and battery storage systems. Results show that the proposed method is feasible, robust and more effective than many previously-developed algorithms.
In this paper, a new family of zero-voltage-transition bidirectional converters are introduced. In the proposed converters, soft switching condition for all semiconductor elements is provided regardless of the power flow direction and without any extra voltage and current stress on the main switches. The auxiliary circuit is composed of a coupled inductor with the converter main inductor and two auxiliary switches. The auxiliary switches benefit from significantly reduced voltage stress and without requiring floating gate drive circuit. Also, by applying the synchronous rectification to the auxiliary switches body diodes, conduction losses of the auxiliary circuit is reduced. In the auxiliary circuit, the leakage inductor is used as the resonant inductor and all the magnetic components are implemented on a single core which has resulted in significant reduction of the converter volume. In the proposed converters, the reverse recovery losses of the converter rectifying diodes are completely eliminated and hence, using the low-speed body diode of the power switch as the converter rectifying diode is feasible. The theoretical analysis for a bidirectional buck and boost converter is presented in details and the validity of the theoretical analysis is justified using the experimental results of a 250W prototype converter. Index Terms— Bidirectional DC-DC converter (BDC), zero voltage transition (ZVT), Soft-switching technique, zero voltage switching (ZVS)
The objective of this paper is to implement a two-phase, interleaved, bidirectional DC/DC converter topology with an improved voltage conversion ratio for electric vehicle (EV) and DC-microgrid systems. In this study, a two-phase interleaved charge-pump topology is introduced to achieve a high voltage conversion ratio with very simple control circuits. In discharge mode, the circuit topology acts as a voltage-multiplier boost converter to achieve a high step-up conversion ratio (48 V to 240 V). In charge mode, the circuit topology acts as a voltage-divider buck converter to achieve a high voltage step-down conversion ratio (240 V to 48 V). The circuit configuration, operating principle, steady-state analysis and the closed-loop control of the proposed converter are presented. Experiments conducted on a laboratory prototype with 500 W power-rating are presented to verify the effectiveness. The maximum efficiency levels in discharge and charge modes are about 97.7% and 98.4% respectively.
This study presents a four-phase interleaved high voltage conversion ratio bidirectional DC-DC converter circuit based on coupled inductors and switched capacitors, which can eliminate the defects of conventional high voltage conversion ratio bidirectional DC-DC converters in terms of high-voltage/current stress, less efficiency and low-power limitation. Parallel channels are used to reduce current stress at the low-voltage side and series connected switched capacitors are used to enlarge voltage conversion ratio, reduce voltage stress and achieve auto current sharing. This paper proposes the operation principle, feature analysis and optimization design considerations. On this basis the objectives of high voltage conversion ratio, low voltage/current stress, high power density, high efficiency and high-power applications can be achieved. Some experimental results based on a 500 W prototype converter (24 V to 48 V at low-voltage side, 400 V at high-voltage side) are given to verify the theoretical analysis and the effectiveness of the proposed converter.
An improved non-isolated coupled-inductor-based high-step-down converter is presented in this paper. Compared with other coupled-inductor-based high-step-down converters, the proposed converter features zero DC-offset current and non-pulsating output current. In the proposed converter, one of the DC-blocking capacitors is connected between the input voltage and the coupled inductor. Therefore, the step-down voltage conversion ratio can be much higher than those of the traditional SR buck converter and the tapped-inductor buck converter. Furthermore, its voltage conversion ratio is linear, which makes control easier. Moreover, due to the DC-blocking capacitors, the DC magnetizing inductance current can be reduced to zero. Thus, the magnetizing current can be positive and negative, and the entire core B-H loop can be used, ranging from the first quadrant to the third quadrant. That is, the utilization of the coupled inductor can be upgraded. Also, due to a discrete output inductor, the proposed converter features non-pulsating output current. In this study, detailed theoretical analyses and experimental results are offered to demonstrate the feasibility and effectiveness of the proposed converter.
A non-isolated dual half-bridge large step-down voltage conversion ratio converter with non-pulsating output current, utilizing one coupled inductor, one energy-transferring capacitor, and one output inductor, is presented herein. The coupled inductor is connected between the input voltage and the output inductor and plays a role to step down the input voltage. Furthermore, the output inductor is used not only to further step down the voltage but also to provide a non-pulsating output current. Moreover, the proposed converter can achieve zero-voltage switching. In this study, detailed theoretical deductions and some experimental results of a prototype with 48V input voltage, 3.3V output voltage, and 10A output current are provided to demonstrate the feasibility and effectiveness of the proposed converter.
In this paper, a bidirectional, nonisolated dc–dc converter with several interleaved phases of multilevel modules for dual low-voltage automotive power systems is presented. Instead of using a two-level stage with short-circuit protection elements, a three-level module in a multiphase structure is proposed to achieve improved fault-tolerance. The dimensioning of the required flying capacitor for multilevel dc–dc converters is described. Further, benefits such as ripple reduction, automatic fault current limitation , and enhanced efficiency are achieved. Moreover, the control strategy for normal operation including the stability of the flying capacitor voltage as well as reconfiguration after semiconductor open-and short-circuit failure for ongoing degraded operation are explained.