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Example event sequences describing how the major SRB pack is determined: (a,b) show the newly added pack assuming the role of major, and (c,d) demonstrate that after the major SRB pack is removed, the SRB with the lowest UID number assumes the role of major.
Source publication
To improve the reliability and energy efficiency of battery swapping, we constructed a battery power network system with active redundancies and with multiple battery management controllers (one in each newly developed smart redundant battery pack). Each pack is getting ready to assume the role of the major to coordinate direct safe mounting of the...
Contexts in source publication
Context 1
... the SRB pack connects to the power bus without a DC/DC converter, a major SRB controller must be chosen among the SRB packs in the system to safely and effectively coordinate the connections of the packs to the power bus. Figure 2 shows how the major SRB pack is determined and how it is replaced by a new one when the previous major pack fails or is removed. Each SRB pack is assigned a unique serial identification (UID) number. ...
Context 2
... SRB pack with the lowest UID number gets the highest priority to assume the role of major. For example, in Figure 2a, the UID number of the newly added Pack3 is 10, which is lower than the UID number of the original major Pack2 (12). After Pack3 is installed, Pack2 no longer acts as the major; it becomes a minor, and Pack3 becomes the new major, as shown in Figure 2b. ...
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... example, in Figure 2a, the UID number of the newly added Pack3 is 10, which is lower than the UID number of the original major Pack2 (12). After Pack3 is installed, Pack2 no longer acts as the major; it becomes a minor, and Pack3 becomes the new major, as shown in Figure 2b. As shown in Figure 2c, if Pack3 has to be removed at a later point in time, it will send an abdicating broadcast message, and Pack2 will again assume the role of major, as shown in Figure 2d. ...
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... Pack3 is installed, Pack2 no longer acts as the major; it becomes a minor, and Pack3 becomes the new major, as shown in Figure 2b. As shown in Figure 2c, if Pack3 has to be removed at a later point in time, it will send an abdicating broadcast message, and Pack2 will again assume the role of major, as shown in Figure 2d. : (a,b) show the newly added pack assuming the role of major, and (c,d) demonstrate that after the major SRB pack is removed, the SRB with the lowest UID number assumes the role of major. ...
Context 5
... Pack3 is installed, Pack2 no longer acts as the major; it becomes a minor, and Pack3 becomes the new major, as shown in Figure 2b. As shown in Figure 2c, if Pack3 has to be removed at a later point in time, it will send an abdicating broadcast message, and Pack2 will again assume the role of major, as shown in Figure 2d. : (a,b) show the newly added pack assuming the role of major, and (c,d) demonstrate that after the major SRB pack is removed, the SRB with the lowest UID number assumes the role of major. ...
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... initial mounting sequence ❶ from the start to 350 s will be described in details in Figure 12. The tests of battery swap, labeled as ❷, during power supply discharging were conducted from 1700 to 1950 s. ...
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... the initiation of a discharge cycle, all packs were connected to the system. First, the most lagging Pack2 with the most energy reserve got mounted on the power bus at 10 s as event ❶ shown in Figure 12. Since Pack2 was the only device connected to the bus without the load demand, í µí± equaled to the OCV of Pack2, namely, 54.7 V. ...
Citations
... In practice, the difference in each cell's characteristics (e.g., internal capacity, impedance, self-discharge rate, etc.) will influence the voltage difference of all the seriesconnected cells of the battery pack. Therefore, a battery management system (BMS) [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] was designed to protect, monitor, and control the state of all cells of the battery pack. A good BMS can ensure safe operation, maximize the available capacity, and provide a real-time estimate of the remaining discharge capacity of the battery pack [19]. ...
This paper proposes a novel hybrid equalizer circuit (HEC) for a battery management system (BMS) to implement the passive HEC (P-HEC), active HEC (A-HEC), or active/passive (AP-HEC) with the same equalizer circuit architecture. The advantages of an HEC are that it is simple, cost-effective, highly energy efficient, and fail safe. The P-HEC can further use a cooling fan or heater instead of a conventional resistor as a power dissipation element to convert the energy of the waste heat generated by the resistor to adjust the battery temperature. Even if the P-HEC uses the resistor to consume energy as in conventional methods, the P-HEC still dramatically improves the component lifetime and reliability of the BMS because the waste heat generated by the equalizer resistor is outside of the BMS board. Three significant advantages of an A-HEC are its (1) low cost, (2) small volume, and (3) higher energy efficiency than the conventional active equalizer circuits (AECs). In the HEC design, the MOSFETs of the switch array do not need high-speed switching to transfer energy as conventional AECs with DC/DC converter architecture because the A-HEC uses an isolated battery charger to charge the string cell. Therefore, the switch array is equal to a cell selector with a simple ON/OFF function. In summary, the HEC provides a small volume, cost-effective, high efficiency, and fail-safe equalizer circuit design to satisfy cell balancing demands for all kinds of electric vehicles (EVs) and energy storage systems (ESSs).
... However, these authors did not verify the situation in which the direction of the charging/discharging load current is changed, nor did they study the characteristics of the battery according to the state change, such as the temperature and aging of the battery [12,13]. Chou et al. conducted a study on the design of a Smart Redundant Battery (SRB) that reflects the direct current internal resistance (DCIR) and pack impedance of the battery (cable, etc.) and the hot-swap conditions that can operate within a set current [14]. Since this study did not consider the hot-swap circulating current, according to the parallel configuration of batteries, it is possible to exceed the current limit of the battery system under the parallel condition of three or more batteries. ...
Battery applications, such as electric vehicles, electric propulsion ships, and energy storage systems, are developing rapidly, and battery management issues are gaining attention. In this application field, a battery system with a high capacity and high power in which numerous battery cells are connected in series and parallel is used. Therefore, research on a battery management system (BMS) to which various algorithms are applied for efficient use and safe operation of batteries is being conducted. In general, maintenance/replacement of multi-series/multiple parallel battery systems is only possible when there is no load current, or the entire system is shut down. However, if the circulating current generated by the voltage difference between the newly added battery and the existing battery pack is less than the allowable current of the system, the new battery can be connected while the system is running, which is called hot swapping. The circulating current generated during the hot-swap operation is determined by the battery’s state of charge (SOC), the parallel configuration of the battery system, temperature, aging, operating point, and differences in the load current. Therefore, since there is a limit to formulating a circulating current that changes in size according to these various conditions, this paper presents a circulating current estimation method, using an artificial neural network (ANN). The ANN model for estimating the hot-swap circulating current is designed for a 1S4P lithium battery pack system, consisting of one series and four parallel cells. The circulating current of the ANN model proposed in this paper is experimentally verified to be able to estimate the actual value within a 6% error range.
