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astra_conv:conversion:distribution_boxes:distribution_boxes [2014/03/18 17:48]
richard
astra_conv:conversion:distribution_boxes:distribution_boxes [2014/06/20 12:56] (current)
richard
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 The ceramic fuses used here are suitable for interrupting high currents at 100V DC (which, by the way, is not the case for 230V AC circuit breakers). The ceramic fuses used here are suitable for interrupting high currents at 100V DC (which, by the way, is not the case for 230V AC circuit breakers).
  
-=== DC/DC converter primary side driver ​and output relay ===+=== DC/DC converter primary side driver ===
  
-The circuit board within the 100V distribution box houses the driver that switches the primary side of the DC/DC converter. ​The actual switching ​is done by an N channel MOSFET. The transistor may seem overrated with 500V 44A, but upon tragic experience with a 14A type I know that it needs some reserves to take up with the inrush current of the converter.  +The circuit board within the 100V distribution box houses the driver that switches the primary side of the DC/DC converter. ​It is described in detail in chapter ​[[astra_conv:​conversion:​dcdc_converter:dcdc_converter|DC/DC converter]].
- +
-The MOSFET is controlled via a small solid state relay, that provides the required isolation between 12V grid and traction grid. +
- +
-A thermo switch next to the source of the MOSFET interrupts the current when the heat sink temperature exceeds 75°C. I have experienced that such situations may occur if water gets into the distribution box and leakage currents elevate the gate voltage into an "​intermediate"​ range. Then the MOSFET will switch incompletely and produce a lot of heat. +
- +
-In the case of the DC/DC primary side driver, it would have been difficult to make a "​water-proof"​ control circuit that drives the MOSFET'​s gate with with low impedance, has a hysteresis that avoids intermediate states and still draws no quiescent current. For some of the other drivers, this might be a possible improvement.  +
- +
-The driver circuit includes two logical "​OR"​s made of three combiner diodes each. The DC/DC converter should operate: +
-  * when ignition is on (trivially) +
-  * when the traction battery charger is active, i.e. 230V is available and the charger has not yet reached the "end of charge or trickle charge"​ state. See also  ​[[astra_conv:​conversion:​battery_charger:battery_charger#​control_in-_and_outputs|here]]. +
-  * when the remote control contact "​OUT1"​ of the GSM module is engaged (either just to charge the 12V battery, or - in case it is switched on - to supply 12V power for the coolant pump and the car's air blower. +
-The GSM module itself is located in the rear distribution box. +
- +
-The first diode combiner controls the primary side DC/DC converter ​driver.  +
- +
-The output of the other one controls a relay that isolates the secondary side of the DC/DC converter. This relay (it is actually located in the 12V distribution box) turned out to be necessary to avoid the reverse current of around 60mA. This current would otherwise flow back from the 12V battery into the converter'​s output when the converter is switched off.  +
- +
-The relay itself required some more control circuitry so that the contact will not close before the output of the converter has already approached around 10V. Otherwise, the reverse inrush current to the converter'​s output capacitor would weld up the relay contact, so it would "​stick"​ and not release any more. +
- +
-Below a view of the DC/DC converter primary side driver. +
- +
-{{:​astra_conv:​conversion:​wiring:​p1100347_dcdc_f.jpg?​600|}} {{:​astra_conv:​conversion:​wiring:​p1100348_dcdc_r.jpg?​600|}} +
- +
-Room for improvement:​ A DC/DC converter that can be switched on and off via a low power control input, that has near-zero idle current and does not draw reverse current would have rendered both the driver at the input and the relay at the output redundant, saving a lot of integration work+
  
 \\ \\
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 === DC/DC converter output relay === === DC/DC converter output relay ===
  
-The purpose of this relay (40A, in the drawing it is located at the top right of the box) has already been described in above subchapter ​[[#​dc_dc_converter_primary_side_driver_and_output_relay|]]+The purpose of this relay (40A, in the drawing it is located at the top right of the box) is described in chapter ​[[astra_conv:​conversion:​dcdc_converter:​dcdc_converter|DC/DC converter]].
  
  
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 === immobilizer relay === === immobilizer relay ===
  
-The little grey box above the main fuse is a relay that deactivates the motor controller in case the driver'​s door is opened ​or the tank lid is open. The relay is controlled ​by a circuit ​located in the rear distribution box, that also drives a warning beeper. This immobilizer function is required by ECE R-100 (only for the "open tank lid" case) to avoid that the car is moved while the charger cable is still connected. See also the similar requirement [[astra_conv:​conversion:​conversion#​sound indicates state of operation|]]. With the current setup, both conditions will trigger both beeper and immobilizer.+The little grey box above the main fuse is a relay that deactivates the motor controller in case the driver'​s door is openedthe tank lid is open or an isolation fault of the traction circuit against the chassis was detected 
 +These three alarm conditions are collected and relayed ​by the [[astra_conv:​conversion:​immobilizer:​immobilizer |immobilizer latch]] that is located in the trunk distribution box. 
 + 
 +This immobilizer function is required by ECE R-100 to e.g. avoid that the car is moved while the charger cable is still connected. See also the similar requirement [[astra_conv:​conversion:​conversion#​sound indicates state of operation|]]. With the current setup, both conditions will trigger both beeper and immobilizer. 
 + 
  
-Room for improvement:​ The immobilizer should not be allowed to engage any more once the car is moving. This would avoid the dangers of the car just stopping on the road just because of a broken door contact or a malfunction of the tank lid position sensor. 
  
 \\ \\
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 Below, circuit diagram and pictures of the HV idle voltage check unit. Below, circuit diagram and pictures of the HV idle voltage check unit.
  
-{{:​astra_conv:​conversion:​distribution_boxes:​hv_idle_voltage_check_02.jpg?​900|}}+{{:​astra_conv:​conversion:​distribution_boxes:​hv_idle_voltage_check_02.jpg?​1000|}}
  
 {{:​astra_conv:​conversion:​wiring:​p1100412.jpg?​600|}} {{:​astra_conv:​conversion:​wiring:​p1100876_volt_check_f.jpg?​600|}} {{:​astra_conv:​conversion:​wiring:​p1100412.jpg?​600|}} {{:​astra_conv:​conversion:​wiring:​p1100876_volt_check_f.jpg?​600|}}
astra_conv/conversion/distribution_boxes/distribution_boxes.1395164895.txt · Last modified: 2014/03/18 17:48 by richard