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Changes for page ACCU MB

Last modified by Lars Skullerud on 2026/09/10 18:12
From version 4.1
edited by Lars Skullerud
on 2026/09/10 17:57
Change comment: There is no comment for this version
To version 7.1
edited by Lars Skullerud
on 2026/09/10 18:12
Change comment: There is no comment for this version

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... ... @@ -73,6 +73,24 @@
73 73  
74 74  The precharge relay and logic is used to charge the car size of the hight voltage system throught a PTC resistor to 95% of the actual TS ACCU voltage before closing the second AIR relay. (Requiered by EV 5.7) This eliminates the inrush current that would otherwise occur due to charging the capacitors in the inverters.
75 75  
76 +{{mathjax}}
77 +$$I(t)=\frac{E}{R}\cdot e^{-\frac{r}{RC}}$$
78 +{{/mathjax}}
79 +
80 +(% class="wikigeneratedid" %)
81 +The charging current of a capacitor with respect to time is shown above. Without the precharge PTC the resitance is very low, making the inrish current very large. By charging the capacitors through the PTC, the inrush current is reduced to acceptable levels.
82 +
83 +(% class="wikigeneratedid" %)
84 +The precharge relay can only dissipate 100W of power, therefor the precharge relay only provides galvanic isolation (required by EV 5.6.2). A MOSFET switches the charging current after the precharge relay coil has been energized and before the precharge relay coil is de-energized. This prevents the precharge relay from switching large currents thus prolonging the life of its contacts. The logic that switches the gate of the MOSFET works by <STIAN PLS HELP!>
85 +
86 +(% class="wikigeneratedid" %)
87 +The precarge sequence is as follows:
88 +
89 +1. AIR+ Closes
90 +1. The precharge relay closes
91 +1. The precharge MOSFET switches the precharge power
92 +1. AIR- Closes after the car side voltage is > 95% of ACCU side voltage
93 +
76 76  == Pinout ==
77 77  
78 78  [[image:under_construction.png||height="366" width="300"]]