Situation:
Today Lovol ECUs include a PWM SW driver for driving external power loads. The SW module generates a
“standard” PWM waveform, and upper SW levels can define frequency and Ton (then duty cycle). This
module, manages up to 6 PWM outputs, with independent settings, that’s the number of power outputs of
the ECU. The module was conceived for driving also the Tecnord proportional valves, that are used for
modulating the clutch pressure in the P2 transmission.
What’s new:
Two weeks ago, after running some valves tests on a Lovol competitor tractor, Tecnord asked for a
technical update of their preliminary valve driving specifications. They detected some “instability”
problems, that were fixed with a different PWM modulation, and forwarded us this information based on
their practical experience. The purpose of the document is not investigating and understanding the reasons
of the problem found by Tecnord, nor trying to understand why their proposal should fix it. It’s possible
that Lovol hydraulic circuits won’t be affected by Lovol competitor’s problems, but in case, we should be
ready to try the fix suggested by Tecnord at the moment we start testing the P2 transmission. That’s why
we need a new PWM driver able to work in a standard way, as well as with the proposed driving. We call
this driving method “Double PWM modulation”.
2Mod_PWM.pdf
(435.39 KB, 下載次數: 6)