With this solution you can fast open low z injectors and fast close(30V flyback) but with 25% pwm(low energy losses on flyback transistor). Hold time is 1ms.
Schematic:
- we are thinking to use MTD20P06LG (ONS) RoHS P-POWERFET 60V 20A DPAK - any objections ?
- NTD2955G seems very cheap 60V 12A dpak $0.27 @1000 digiprice
- note: some schematic is for only bipolar transistor (zx5t3 is good bipolar transistor). With mosfet we need zener diode and one more resistor
- double diode: MBRB20100CT (in stock at lomex, D2PAK, 83.50 ft each)
- diode : I use by500-1000 (cheap, fast)
- I put zener diode on vems board 30V transient protection diode (1k5E30 diode from WebShop)
- so when pwm is activated, current flow through active flyback, but when injector needs to close, 30V high voltage flyback inside VEMS does the clamping
Same schematic, but drawn in a slightly confusing way:
When pwm last, flyback voltage is 0.3-1.5V(depending of schottky diode and mosfet(irf9540))
Bad thing is, you must have one of thise flyback for every injector.
PCB
Assembled board(missing 2 zener diodes, i bought two too few)
That board was tested on lpg injectors(landi renzo, 0.9ohm) and working well.
Hi,
could you please share the LPG injector setting you used?
What is the max output these can handle?
Whats the minimum opening time?Whats the max allowed Duty?
Thanks,
Peter
- peak time 1.5ms, 25% DC (landi renzo "white" injectors)
- injectors are good for 40kW per one cylinder
- open time is about 400us, max duty is imho 100%. My car is running with 96% DC without problems