Automotive Load Dump

The "MOV" folks had a paper I read once....

From memory; 65+ v, 500ms or longer.

web

stuff

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And still the ever present battery with a resistance of a few milliohms versus a few hundred milliohms of electronics load. The load dump in = both cases easily reaches 100 V. The battery resistance (conductance) dominates the parallel circuitry. The series resistance and inductive reactance of the wiring gets into it as well, being appreciable wrt the battery resistance.

?-)

This Intel app note has an automotive section and a load dump section which we referred to regularly at a fuel injector company I used to work for:

Best, EdV

A diesel has no fuel pump in the tank. The crankshaft drives the injection pump through the timing belt. Depending on the actual model the VW TDI may not need much electricity to keep working as long as the cut-out valve is kept open. Modern diesels have more electronics to keep the motor running.

Modern Diesels are moving towards a common high-pressure rail, using an electric pump, with electrically operated injectors, electronically controlled. No calibrated distribution pump, or equal-length "transmission line" pipes adding to the noise.

I have designed the electronics for an injector, although that one was for aerospace. In contrast to the "classic" ones it uses less than 2W while injecting and next to nothing otherwise.

Doing power stuff electrically in a car is a double-edged thing. It may be more quiet or cheaper but now there is one more source of energy loss plus one more link that can bring down the whole system: The alternator, plus to some extent the battery and cabling.

I looked at doing a driver for gasoline direct injection.

the injectors are ~1R, ~150uH

a boost converter is used to make 60V to open injector, it gets the coil current up to ~10A , then 5A holding current via PWM hold it open, sometimes multiple injections are used

-Lasse