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Changes for page 3.4 Battery parameters

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... ... @@ -162,10 +162,71 @@
162 162  * Coulomb threshold – the difference of the charges Qthr, given by a series of cells, above which balancing to be started, Ah;
163 163  * Period – period to reset of charge counters for each series (to avoid accumulation of error), second.
164 164  
165 -== ==
165 +== 3.4.6 Cell analysis ==
166 166  
167 -== ==
167 +Discharge characteristics of the battery – the dependence Uocv = Uocv (DOD) – is used to determine the tabular dependence Uocv = Uocv (SOC, t °C) (see section Calculating the state of charge (SOC)), which is necessary for calculating the state of charge of the battery.
168 168  
169 +The BMS Main 2.x board can automatically determine the battery discharge characteristic.
170 +
171 +Before starting the process of determining the discharge characteristic, it is necessary to prepare a BMS:
172 +
173 +1. Charge the battery.
174 +1. Connect a contactor to the discharging relay which switches the resistive load to the battery.
175 +1. Connect a resistive load to the contactor, which will provide a discharge current of 0.5C (where C is the cell capacitance).
176 +
177 +To configure parameters for determining the discharge characteristic of the battery, select the menu "Cells → Cell analysis":
178 +
179 +[[Cell analysis section>>image:1732207696322-587.png||data-xwiki-image-style-alignment="center" height="213" width="258"]]
180 +
181 +In this section:
182 +
183 +* Enable – a flag to enable cell analysis;
184 +* Discharge step, Ah;
185 +* Delta voltage – a maximum allowable voltage drop for the cell, V;
186 +* Logic index – an address of the BMS Logic board to which the analyzed cell is connected;
187 +* Cell index – a position of the analyzed cell connected to the BMS Logic board;
188 +* Analyse cell with minimum voltage – a flag to analyse of the least charged cell (in this case, the values of Logic index and Cell index are ignored).
189 +
190 +Discharge step should be set equal to
191 +
192 +Discharge step = С/21,
193 +
194 +where C is the cell capacity.
195 +
196 +The discharge characteristic will be constructed for the given cell (its position is determined by the fields Logic index and Cell index).
197 +
198 +The algorithm for determining the discharge characteristic of the battery will be started if the Enable flag is set. From this moment, the control of the discharge relay is performed by this algorithm.
199 +
200 +Algorithm steps:
201 +
202 +1. DOD = 0.
203 +1. Disconnecting the discharge relay.
204 +1. Waiting for the relaxation of the battery.
205 +1. Measuring Uocv = U.
206 +1. Saving the point of the discharge characteristic (Q, U,,OCV,,).
207 +1. Activation of the discharge relay. DOD,,1,, = DOD + Discharge step, U,,1,, = U
208 +1. If DOD = DOD,,1,, or U < (U,,1,, – Delta voltage), then go to step 2.
209 +1. If the "Undervoltage" error is detected, then the end of the algorithm.
210 +
211 +During the operation of the algorithm, a file with the name "CELLANALYSIS.TXT" in the CSV format will be created on the SD card.
212 +
213 +File structure:
214 +
215 +|**Time**|**DOD**|**Logic**|**Cell**|**OCV**|**Resistance**
216 +|**10.11.2017 12:28:34**|0.0|1|1|4.180|0.080000
217 +|**...**|...|…|…|...|...
218 +
219 +Parameter names:
220 +
221 +* Time – date and time;
222 +* DOD – depth of discharge, Ah;
223 +* Logic – the address of the BMS Logic board to which the analyzed cell is connected;
224 +* Cell – position of the analyzed cell for which OCV and Resistance values are provided;
225 +* OCV – cell voltage Uocv, V;
226 +* Resistance – cell resistance, Ohm.
227 +
228 +
229 +
169 169  == SOC correction ==
170 170  
171 171  The BMS Main 2.x board can recalculate the battery SOC after long-term storage or after long-term working in the case when the battery was not charged fully or discharged totally. Recalculation is done based on the tabular dependency Uocv = Uocv (SOC, t) (see section Calculating the state of charge (SOC)).