Implementation of a Regenerative Pulse and Equalization Battery Charger Using a DSP

This report demonstrates improvements made in battery charging and battery management technology through the design of a universal programmable battery charger with optional battery management system attachment. This charger offers improvements in charge efficiency and unique battery charging algorithms to charge a variety of battery chemistries with variety of power requirements. Improvements in efficiency result from a synchronous Buck Controller topology as compared to previous universal chargers that use asynchronous Buck-Boost Converter topologies. This battery charger also surpasses current universal battery chargers by offering different charge modes for different battery chemistries. Charge modes provide the user an option between extending the life of the battery by selecting a mode with a slower, less stressful charge rate or a shorter charge time with a fast, more stressful charging mode. The user can also choose a charge mode in which the battery charges to full capacity, resulting in maximum runtime or a less than full capacity, which puts less stress on the battery thus extending the lifetime. Ultimately, this system permits weighing the performance tradeoff of battery lifetime and charge time. The optional battery management system attachment offers more precise monitoring of each cell and cell balancing for Li-Ion batteries. This further enhances the performance of the charger when integrated, but is not necessary for charger operation. The battery charger consists of three subcircuits: A microcontroller unit, a power stage, and a current sensing circuit. A C2000 Piccolo F28069 microcontroller controls a LM5117 Buck Controller by injecting a pulse-width modulated signal into the feedback node controlling the output of the buck to set a constant current or constant voltage thus creating a programmable battery charger. The pulse-width modulated signal changes according to charge algorithms created in software for specific battery chemistries and charge requirements. An analog-to-digital converter on the microcontroller monitors battery voltage by using a voltage divider and an INA169 current shunt monitor, which outputs a voltage corresponding to the charge current to another analog-to-digital converter on the microcontroller, monitors the charge current. This allows the charger program to maintain correct and safe charging conditions for each charge mode in addition to measuring output power. Lights on the microcontroller display a real-time status to the user of which portion of the charge profile the charger is in. A solid red light means the charger is in the constant current portion of the charge profile. A blinking red light means the charger

A bridgeless bidirectional flyback converter module that enables the battery of an electric vehicle to be used as an inverter or as an emergency power backup device for powering critical residential loads is proposed in this paper. Incorporating solar panels with this system helps in the prolonged use of the Electric Vehicle (EV) battery as an inverter module and avoids the possibility of total depletion of the battery module. The different modes of operation include Plug-in Charging, Solar Photo-Voltaic (PV) Charging and an Emergency Power Backup mode. The main circuit developed for this project includes a 48V 20Ah Li-ion battery module, a 250Wp Solar Panel module, a Bi-directional Flyback converter capable of both rectifying and inverting modes of operation for charging the EV battery as well as powering critical loads in the respective residential buildings, a charge controller to provide Constant Current Constant Voltage (CCCV) mode of charging and control circuits to provide the necessary control signals for the converter switches (MOSFET's). The simulation results in this paper were achieved through MATLAB 2020b's Simulink software.

Decarbonization policies worldwide encourage the use of renewable energy to generate electricity and electrify transport. In line with these policies, the use of energy storage systems in electric vehicles can support the integration of renewable energy as a resource called V2G (vehicle to grid). This system of equipment has a problem because the energy it produces can’t be directly injected back into the grid. An essential element of the V2G system is the bidirectional converter which can charge and discharge EV batteries. Research related to bidirectional converters has been developed a lot. One of these converter topologies that have a wide output voltage range and smaller current ripple is the H-bridge bidirectional converter. In addition to the type of converter topology that must be selected, a current control method that can respond to dynamic changes quickly, accurately, and is simple to implement is also very important. Using fuzzy logic, this research aims to control the DC-DC current converter with adaptive hysteresis bandwidth. On the other hand, the adaptive HB variable is expected to limit MOSFET performance at high and irregular frequencies that make switching losses and frequency noise. To improve the quality of the output current, frequencies are limited. Simulations were conducted using PSIM and co-simulation with Simulink to validate the proposed control performance. The results show fuzzy logic is a good method to make an HB adaptive and the frequencies were around $9.23 k H z \leq f \leq 9.49 k H z$. It is very possible to make the microcontroller and MOSFET work according to the work frequency capabilities.

An improved control for a stand-alone WEC system involving a Vienna rectifier with battery energy storage management

This research aims to address challenges in efficient energy storage in electric vehicles, particularly those using lithium-ion batteries. The research focuses on voltage imbalances in battery packs with cells connected in series, which can reduce the battery pack's lifespan. We investigated active balancing charging methods using bidirectional fly-back converters in both pack-to-cell and cell-to-pack modes. Current charging methods face limitations such as prolonged balancing times, circuit complexity, and low efficiency. To overcome these challenges, this research proposes integrating an artificial intelligence approach using adaptive neuro-fuzzy inference system (ANFIS) control. This approach allows for dynamic adjustment of duty cycles, expediting the balancing process. Experimental results show that employing ANFIS control can significantly reduce balancing times. In pack-to-cell mode, balancing time decreased from 660 seconds to 600 seconds, while in cell-to-pack mode, it decreased from 660 seconds to 580 seconds. This research makes a significant contribution to the development of more efficient charging technology for lithium-ion batteries in electric vehicles. Its potential implications include improved battery lifespan and electric vehicle performance in the future.

High Capacity Li-ion and Pb-acid batteries are widely used in present Renewable Energy and EV applications. Consequently, charging these batteries in a minimum amount of time whilst maintaining efficiency is crucial. The need for fast charging has brought up the method of Pulse Charging. However, present pulse charging methods which involve hard-switching, pose problems due to switching losses in the semiconductor devices. This paper presents a Fast Pulse Charging mechanism for High Capacity Pb-acid and Li-ion Batteries which minimizes switching losses by Soft Switching. The operation of the methodology is centered on the Fully Clamped Quasi-resonant DC Link Converter which strategically generates current pulses to charge the battery in both Constant Current (CC) and Constant Voltage (CV) phases. Switching losses are minimized by exploiting Zero Current Switching (ZCS), and the simulated results show that this can be achieved for higher switching frequencies further reducing the circuit size. Experiments were carried out by the research group for both conventional CC-CV method and for current pulse charging method. The results professed that proposed methodology reduces the charging time of Pb-acid batteries by 14.01% in comparison to the conventional CC-CV charging method.

ABSTRACTThis paper proposes a charge-equalisation circuit for series-connected battery pack based on direct charge transference. The battery cells inside the pack can mutually transfer their charges directly via the bidirectional flyback converter within this proposed charge-equalisation circuit. Since electric charge is transferred directly between the highest and lowest charged cells, the losses dissipated during the transfer processes can be minimised. Meanwhile, the equalisation time can be reduced. A battery-management IC is used to detect the cell voltages and drive the battery-selection switches. A battery pack that consists of four series-connected Li-ion battery cells is used in the experiment. The charge-equalisation circuit topology and its control scheme are verified by experiments. From the experimental results, the proposed circuit is able to shrink the maximum voltage difference between cells into 30 mV range after 170min. The results successfully verify the feasibility of the circuit topology and the control scheme.

Due to the increasing awareness and adoption of eco-friendly vehicle technologies, hybrid electric vehicle (HEV) and plug-in hybrid electric vehicle (PHEV) technologies have become one of the most interesting areas of research because of the reduced use of fuel and green house emission. Battery chargers are one of the most important parts in developing the HEV's and PHEV's. The various existing optimal battery charging techniques are constant current (CC)-constant voltage (CV) charging, pulse charging and reflex charging. The major problem with these conventional optimal battery charging techniques are that different circuits are needed for adopting different optimal charging techniques. This paper presents design and implementation of a field programmable gate array (FPGA) based versatile optimal bidirectional digital battery charger for HEV/PHEV. The proposed digital optimal charger is capable of adapting all the existing optimal battery charging techniques i.e., constant current-constant voltage (CC-CV) charging, Pulse charging and Reflex charging in a single circuit. The proposed system uses a bidirectional magnetically coupled inductor topology with a damping network. When the proposed system adapts CC-CV charging technique, it shows automatic and smooth transition from CC to CV mode without using any extra switching circuit and when the proposed system adapts pulse and reflex charging techniques it gives regulated charging and discharging currents. Modeling, analysis, and simulation have been carried out on a 250W prototype to validate the proposed algorithm.

This paper proposes an on‐board integrated battery charger for an electric‐propulsion system. The system includes a rectifying diode bridge, an inverter, a permanent magnet motor, a digital signal processor, a battery set and three relays. By suitably controlling the three relays and the power switches of the inverter, the proposed system can be operated as either an electric‐propulsion system or a battery charger. The integrated battery charger can be used to charge a 48 V battery set or a 192 V battery set from a single‐phase 110 V rms grid. The battery charger can be operated in a boost‐converter charging mode or in buck‐converter charging mode with input power factor higher than 0.9 when operating with 48 V battery or 192 V battery, which can meet the IEC 1000‐3‐2 standard. Only a diode bridge, an inductance‐capacitance (LC) filter, and three additional relays are required in addition to the components for propulsion. The windings of the motor and the power switches of the inverter are shared for both the electric‐propulsion system and the battery charger. A digital signal processor, TMS‐320‐F‐2808, is used to execute all of the control algorithms. Experimental results validate the theoretical analysis and separately show the correctness and feasibility of the proposed method.

Purpose – The purpose of this paper is to analyze and simulate the control techniques that can be used to control the on-board conductive battery chargers (OCBCs) for electric vehicles applications. This paper also provides a comparative study of these control techniques. Design/methodology/approach – Battery chargers would play an important role in the development of new battery electric vehicles (BEVs). The control techniques of these OCBCs can significantly influence the BEV performance during the charging mode from the ac grid. In addition, the proper selection of control systems of the OCBCs has a great impact on the power quality of the AC grid during the charging period. Therefore, this paper presents the analysis of different control techniques that are commonly used to control the battery chargers. In addition, a comparative study of different control techniques of the OCBCs for BEVs is provided. Findings – The results have demonstrated that it is possible to significantly improve the efficiency, power factor and total harmonic distortion by using proportional-integral control and proportional-resonant control. The digital control can be used to validate the selected control technique. Originality/value – The main objective of this paper is to analyze the different control methods that can be used to control the OCBCs during charging mode from the ac grid. In addition, this paper presents a comparative analysis between these control methods. In this paper, a digital control based on TMS320F2808 DSP is used to implement the proper control method for OCBCs.

This paper proposes a multimode onboard charger with three simultaneous outputs (one AC and two DC in motoring mode; three DC outputs in charging mode) and reduced switch count for electric vehicles (EVs). In multimode operation, it behaves as an inverter in motoring mode and battery charger in charging mode. Thus, eliminates the requirement for two separate converters resulting in reduced overall system's switch count. In motoring mode, inverter drives the Brushless DC (BLDC) motor using High-PWM-Low-ON switching (HPLS) scheme. In the charging mode, the system is transformed into a front-end converter with half-bridge LLC (HBLLC) converter which maintains unity power factor (UPF) at the source and charges the battery with constant-current constant-voltage (CC-CV) optimal charging technique utilizing a single control loop. The design equations of the converter are derived and its performance with cost comparison are presented. The operation of the proposed charger is validated using a laboratory-developed prototype to charge a 36 V battery from 120 V, 50 Hz supply while maintaining UPF in charging mode; and driving a 1000-watt, BLDC motor in motoring mode. Additionally, it generates 48 V and 12 V for auxiliaries, thereby eliminating the need for an extra 12 V battery and its charger.

Aiming at the temperature inconsistency of series-connected lithium-ion battery packs, a thermal balance control strategy for lithium-ion battery packs based on bi-directional flyback converters is proposed. This strategy can ensure that the system tracks the reference value of the output power of the system, and uses the surface temperature of the lithium-ion battery as the balance criterion. By adjusting the balance current of the bi-directional flyback converter circuit, the temperature balance in the series-connected lithium-ion battery pack can be achieved. It overcomes the battery inconsistency problem caused by the high temperature of batteries, avoids the safety problems of battery pack life degradation or thermal runaway caused by the short-board effect of accelerated aging of some cells, and ensures the stability and safety of the system. A simulation experiment was carried out on the MATLAB/Simulink and COMSOL co-simulation platform to verify the effectiveness of the control strategy.

This paper proposes a bidirectional CLLC resonant converter for battery charging applications. In order to enhance the charging performance as well as to extend the battery life, five charging methods are adopted, which are (1) the constant-current (CC) charging, (2) the pulse-ripple-current (PRC) charging, (3) the sinusoidal-ripple-current (SRC) charging, (4) the bidirectional pulse-ripple-current (BPRC) charging and (5) the bidirectional sinusoidal-ripple-current (BSRC) charging. In addition, an optimal frequency-modulated control (OFMC) strategy will be developed. With the OFMC, the switching frequency will dynamically be regulated to achieve fast system response. Under the BPRC and BSRC charging scenarios, the charging and discharging current magnitude might be different. Therefore, the resonant tank gain of the dc-link side and the battery side will be designed independently. As a result, the charging/discharging performance could be increased. In this paper, detailed operational principles and mathematical derivations will also be revealed. The proposed multi charging methods and the OFMC could be realized by the digital signal processor (DSP) without adding extra circuit and components. Finally, simulation results obtained from a 720W CLLC prototype circuit verify the performance and feasibility of the proposed circuit and control strategies.

A power balance control strategy for stand alone wind energy conversion systems

A conventional power supply was designed with two stages, the former stage function as a power factor corrector (PFC), and the latter stage is a DC/DC converter which regulates the output voltage of the system. However, the cost and energy conversion efficiency of the two-stage system is higher than a single-stage one. LLC resonant converters not only have characteristics of high efficiency and low noise but also are easy to control. This circuit topology is becoming more and more widely used in application of power conversion. The duty cycle of both MOSFETs of a LLC converter is 50% that is different from a traditional PWM converter. The output regulation is control by modulation of frequency, in the ZVS region, the energy from primary side to load increases as the switching frequency decreases. In this thesis, a single-stage LLC resonant converter which combines a boost-type PFC cell and an LLC resonant DC/DC cell is proposed. The control method of it is the same as a conventional LLC resonant converter that regulate output voltage by modulating switching frequency. When the load increases, the switching frequency decreases so that the LLC gain increases and more energy can be transferred by input inductor due to longer charging time. The proposed circuit could not only reduce components and circuit size but also increase the power conversion efficiency. It has no control of the voltage of the DC-bus capacitor because there is no separate converter that can control it as there is in a two-stage converter. The capacitor voltage is dependent on the energy equilibrium established between the energy flowing into the capacitor from the input inductor and the energy flowing out of the capacitor and transferred to the output. Therefore, the characteristics of LLC tank are investigated and a new LLC design consideration is proposed, which insures the DC-bus capacitor voltage can be kept in a tolerable region. Finally, an experimental circuit is implemented to verify the analysis.