Concept of a versatile and mobile charging system for different E-Bike Accumulators Technik 317 Aufrufe Speichern Drucken Weiterleiten PDF an Freunde weiterleiten: Ihre IP-Adresse wird aus Sicherheitsgründen gespeichert um kriminelle Aktivitäten und unerlaubten Spam zu unterbinden. Leiten Sie nur E-Mails weiter, wo der Empfänger mit dem Versand auch einverstanden ist. Ihre E-Mail Adresse Ihr Name Empfänger E-Mail Adresse Empfänger Name Ihre zusätzliche Nachricht Eigene PDF Hochladen PDF & Publisher Info (QR-Code downloaden) Deggenhausertal, 18.10.2021 https://pdf-ins-internet.de/?p=106770 A technical description of an dcdc-converter for charging e-bike accumulators. A technical description of an dcdc-converter for charging e-bike accumulators. Teilen: accumulatorchargerconverterdcdce-bikestepup Concept of a versatile and mobile 12V to 24V charging system for different E-Bike Accumulators Wilhelm Richter M.Sc. 25, July 2021, Deggenhausertal, Germany wilhelmrichter@web.de Abstract-This paper introduces a concept of a versatile and mobile charging system for E-Bike accumulators as a useful accessory on a camping trip. It combines multiple communication protocols of different bike manufacturers and can be powered either by a 12V or 24V vehicle electrical system or by a pho- tovoltaic solar panel. With the help of special intelligent cables, unique for every accumulator, the charger can detect the correct accumulator type and select the proper communication protocol as well as the right end-of-charge voltages. The appropriate charging voltage is transformed by a boost converter. By applying Maximum Power Point Tracking (MPPT), the charger is able to use the optimal output power of a photovoltaic power system and can also protect a vehicle battery from being deeply discharged. Index Terms-Charging System, MPPT, E-Bike, Li-Ion ac- cumulator, Li-Ion charging system, BOOST Converter, analog multiplexer I. INTRODUCTION Bicycles have always been a convenient way to explore travel destinations, especially on camping trips. Over the course of the electrification of drive systems, they are more and more replaced by e-bikes, which allow to cover longer distances while leaving the cars or campervans at the camp- site. But since the different manufacturers of E-Bikes and drive trains use various accumulators with unique plugs and communication protocols, there are several chargers necessary on a trip with family or friends, where not everybody has the same bike or accumulator system. This is were a mobile and versatile charging system would be helpful by making it possible to charge all types of accumulators with only one charger. To get a quick overview of the most important systems at the market, three different manufacturers and accumulator types are shown in Section II. Section III addresses the basics of Li-Ion chargers in general. After that, the main parts of the versatile mobile charger are described by covering the intelligent cable system in combination with the analog switch mechanism in order to detect the correct accumulator type and to choose the proper communication protocol in Section IV, and the power input and transformation mechanism in section V, which allows the use of either a 12V vehicle electrical system or photovoltaic cells as a voltage source by using Maximum Power Point Tracking (MPPT). Finally a conclusion together with a quick summary is given in Section VI.II. OVERVIEW OF SYSTEMS IN THEMARKET In the current market there are several bike brands with different drive trains from bigger manufacturers like BOSCH, Shimano, Panasonic and also smaller ones like Stromer. They use accumulators with nominal voltages of 26V, 36V and in the latest versions also 42V. They all use intelligent charging systems which communicate with the accumulator in order to get information about the optimal charging conditions or to monitor the current temperature for safety reasons. Fur- thermore they mostly use different plugs for the connection. Therefore for every system a corresponding charger is required in order to provide the correct plug and communication protocol. Shimano for example uses a UART communication, while Stromer accumulators communicate via CAN bus [1]. Bosch and Panasonic accumulators on the other hand need a 5V level on the NTC (Negative Temperature Coefficient Resistor) pin of the accumulator in order to activate charging mode via the internal battery management system (BMS). So the task is to build a charger, which is able to communicate by different protocols and also to apply different voltage levels to some pins of the plug. III. BASICS OFLI-ION CHARGERS Beside the communication protocols, accumulators are mostly build of Lithium Ion (Li-Ion) rechargeable cells. They are commonly used in E-Bikes due to different advantages such as light weight, small package size and a high charging and discharging efficiency in combination with a high number of charge cycles. They need a loading strategy which applies a constant current (CC) to the accumulator first. With rising state of charge the clamping voltage between the poles rises until it reaches the cell-specific end-of-charge voltage. From this point on, the charger must switch to a constant voltage (CV) mode in which it supplies enough current to keep the clamping voltage constant. The minimum amount of current necessary for keeping up the voltage declines with time until it reaches a certain level in which the accumulator is considered fully charged [2]. This scheme is shown in Fig. 1. When the higher constant current from CC mode would be applied any longer after the end-of-charge voltage is reached, the voltage would rise above this critical level and could damage the cell due to chemical processes inside, which would also heat it up. Eingestellt über www.PDF-ins-Internet.de - Haftung für Inhalt und Inhaber aller Rechte ist der Puplisher Kontaktdaten und Anbieterkennung des Puplishers/Autors entnehmen Sie bitte dem PDF-Archives auf www.PDF-ins-Internet.de. Current Voltage TimeCC CV Fig. 1. Li-Ion charging strategy with constant current (CC) and constant voltage (CV) mode. The typical nominal voltage for a Li-Ion cell is 3.6V or 3.7V, while the typical end-of-charge voltage is 4.2V. So the usable range is between this charge voltage of 4.2V and the typically final-discharge voltage of 2.8V per cell [3]. To get the typical nominal system voltages of the E-Bike accumulator of i.e. 36V, several cells are arranged as a package with 10 cells in a row and multiple cells in parallel, depending on the capacity of the package. This makes a voltage range between 28V and 42V for a 36V nominal accumulator. The ranges for the others nominal voltages are given in table I respectively. TABLE I NOMINAL VOLTAGEVNOM,MINIMAL VOLTAGEVMIN,AND MAXIMAL VOLTAGEVMAXFOR THE DIFFERENT PACKAGES. V NomV MINVMAXCells in Row26V19.6V 29.4V 7 36V28V 42V 10 48V36.4V 54.6V 13 Considering this voltage ranges, the charger must be able to provide a voltage between 19.6V and 54.6V while being powered by a 12V battery of a campervan or car or by a photovoltaic cell with a typical voltage between 10V to 20V [4]. An easy, cost efficient and space saving design for this task is based on a boost or also called step up topology [5], which basic schematic is shown in Fig. 2. It can handle a wide input range as long as it is lower than the output voltage. Its basic function is to increase the input voltage.DCDC-StepUp Converter C1Q1D1 L1 UinUout DCDC-StepUp Converter C1Q1D1 L1 UinUoutFig. 2. Basic schematic of the boost topology. The boost converter is controlled by a pulse width modula- tion (PWM) signal which drives transistor Q1. With the dutycycleDof the PWM signal, which is defined by the ratio of its on-time (Ton) to its period-time (T) D=TonT ,(1) the output voltageVoutcan be set into relation with the input voltageVinby the equation V out=11-D·Vin.(2) The PWM signal is controlled by a microcontroller in order to generate the required voltage or current according to the charging mode (CC or CV) as described in Fig. 1. IV. INTELLIGENT CABLE ANDCOMMUNICATION PROTOCOL SWITCH MECHANISM If several accumulators should be supported by the charger, a mechanism to switch between the different communication protocols is required. Communication Interface MUX2 Logic S0 S2 MUX2 Logic S0 inputs to the output. With two multiplexers per accumulator two-wire protocols like UART or CAN could be selected. The outputs of each multiplexers would be wired to the accumulator plugs, which are realized by an intelligent plug system which is shown in Fig. 4.Cable-Connector Memory -EEPROM -FRAM -... Memory -EEPROM -FRAM -... SDA R1 R2 R3 R4 HW-Coding VDDVDD R1 R2 R3 R4 HW-Coding VDDVDD HW1 HW2 Accu+ Accu- DATA1 DATA2 VDD VDD NTC Cable Accu- ConnectorCable-Connector Memory -EEPROM -FRAM -... SDA R1 R2 R3 R4 HW-Coding VDDVDD HW1 HW2 Accu+ Accu- forming circuit. So the microcontroller must drive the Mosfet Q1 from Fig. 2 in order to keep the load in the maximum power point. This leads to the drawback of powering the charger by a solar module. If the radiation is too low, the accumulator can"t be charged with the maximum charging current, which leads to longer loading times. In the constant voltage section, there is also a lack of efficiency since the current for the maximum power point could be too high which might lead to a less efficient operating point, especially near the end of the charging process. When powered by a car battery, the controller can also monitor the input voltage and turn off the charge process in case that the voltage drops below a critical level, to protect the car battery from being deeply discharged. In Fig. 6 the complete system from the source to the accumu- lator is shown. VI. CONCLUSION This introduced mobile and versatile E-Bike charger would be a useful device for a camping trip with several E-Bikes from different manufacturers. Combined with a solar panel module it can also be used for trips in the outback, were no electricity is available. The boost topology allows relatively small spacing with a good efficiency and with the accu- specific intelligent plug system, the charger can detect and load different accumulators automatically. It can also be designed with two boost converter circuits, which makes it able to charge two accumulators at the same time. This makes it very convenient especially for a couple on a camping trip. REFERENCES [1] myStromer A G.,"Instruction Manual: CR 246", https://www.fietsaccuwinkel.nl/wp-content/uploads/Strom er-CR246-Gebrauchsanleitung-Instruction-Manual.pdf, accessed on July 21, 2021 [2] W eixiangShen, "Char gingAlgorithms of Lithium-Ion Batteries - an Overview", https://ieeexplore.ieee.org/document/6360973, accessed on July 21, 2021 [3] Electronics Lab .24 March 2016, "Ho wto reb uilda Li- Ion pack", https://web.archive.org/web/20120217001508/http: //www.electronics-lab.com/articles/LiIonreconstruct/How%20to% 20rebuild%20a%20Li-Ion%20pack.pdf, accessed on July 21, 2021 [4] M. Se yedmahmoudian,B. Horan, "Ef ficientPhoto voltaikSystem Maximum Power Point Tracking Using a New Technique", https: //www.researchgate.net/publication/296686425EfficientPhotovoltaic SystemMaximumPowerPointTrackingUsingaNewTechnique, accessed on July 21,2021 [5] A. B. Kancherla, "DESIGN OF SOLAR-PV OPERA TEDFORMAL DC-DC CONVERTER FED PMBLDC MOTOR DRIVE FOR REAL- TIME APPLICATIONS", https://ieeexplore.ieee.org/document/9358813, accessed on July 22, 2021 [6] N. Femia, G. Petrone "Optimization of Perturb and Observ eMaximum Power Point Tracking Method", https://ieeexplore.ieee.org/document/ 1461481, accessed on July 22, 2021Cable-Connector Memory -EEPROM -FRAM -... Memory -EEPROM -FRAM -... SDA R1 R2 R3 R4 HW-Coding VDDVDD R1 R2 R3 R4 HW-Coding VDDVDD HW1 HW2 Accu+ Accu- DATA1 DATA2 VDD VDD NTC Cable Accu- ConnectorCable-Connector Memory -EEPROM -FRAM -... SDA