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OpenRevolt not turning on power

882 Views 2 Replies 2 Participants Last post by  alvin
Before I start tearing parts out and replacing/resoldering components I'm hoping someone here has a better suggestion for the root cause. The OpenRevolt controller - a "stock" MOSFET version - was working before I stopped driving the little van for the winter.

The only thing that happened over the winter is that I added 5 new cells, so now at 45 LiFe (144 nominal). Voltage reads 148.x V for the whole pack.

The symptom is that although the controller seems to be working correctly there is no power output - no voltage across the motor and the motor doesn't spin.

It appears to be a problem on the 12V side of the isolated 12/12V converter. An obvious conclusion is that that particular component has failed. It does however seem unlikely (but not impossible) that it just quit. More likely there is a problem elsewhere that has either trashed that component or is causing an issue that looks as though that component has quit - drawing too much current might be a good way to do that.

Suspiciously, it looks as though there might be a short between the two grounds. That is, the voltage I get measuring the output of the converter seems about the same as if I measure from the output of the converter to the 12V (chassis) ground - about 30V. Looking, I can see none, but I'm not sure of all the places to look. This could also be a coincidence or be caused by the converter failing.

No smoke, not obviously failed components (that I can see). The processor appears to be working fine - flashes the orange LED then brings in the contactor, sends values out through the serial port, etc.

Anyone have any ideas?

Thanks,

Some more details in case they are useful.

DC/DC still seems to be functioning - headlight/tail lights come on, main contactor clicks in, orange LED on the board comes on, etc.. Measured output is about 12V (11.7?).

Controller Config (unchanged since last running):

Kp=002 Ki=160
throttle_min_raw_counts=0306 throttle_max_raw_counts=0493
throttle_fault_raw_counts=0100
throttle_pos_gain=008 throttle_pwm_gain=000
current_ramp_rate=006
rtd_period=02000
pwm_filter=0
motor_os_threshold=0000 motor_os_ftime=1000
motor_os_dtime=10 pwm_deadzone=05
motor_speed_calc_amps=000
battery_amps_limit=000
precharge_time=070

RTD output when sitting idle:

TR=000 CR=000 CF=004 PW=000 HS=0509 RT=0503 FB=00 BA=000 AH=000.0
(throttle_ref, current_ref,current_fb,PWM output,raw_hs_temp,raw_throttle, fault_bits,battery_amps)

Move the throttle and the throttle raw and reference change as do the PWM and commanded AMPS (but not the actual amps). Still no faults:

TR=248 CR=248 CF=004 PW=510 HS=0509 RT=0402 FB=00 BA=004 AH=000.0
TR=259 CR=259 CF=004 PW=510 HS=0509 RT=0398 FB=00 BA=004 AH=000.0
TR=281 CR=281 CF=004 PW=510 HS=0509 RT=0390 FB=00 BA=004 AH=000.0
TR=284 CR=284 CF=004 PW=510 HS=0509 RT=0389 FB=00 BA=004 AH=000.0
TR=377 CR=377 CF=004 PW=510 HS=0509 RT=0355 FB=00 BA=004 AH=000.0
TR=374 CR=374 CF=004 PW=510 HS=0509 RT=0356 FB=00 BA=004 AH=000.0
TR=352 CR=352 CF=004 PW=510 HS=0509 RT=0364 FB=00 BA=004 AH=000.0
TR=109 CR=109 CF=004 PW=510 HS=0509 RT=0452 FB=00 BA=004 AH=000.0

Temperature (HS) kicks in at 675, so should not be limiting.

THROTTLE_FAULT
VREF_FAULT
PRECHARGE_WAIT (I see this flashing the LED but can't connect fast enough to see the FB)
MOTOR_OS_FAULT
HPL_FAULT

Will all cause the fault bit to be non-zero so, with some degree of certainty those don't exist.

The OpenRevolt schematic is hard to find on the web - copy attached.

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Discussion Starter · #2 ·
Answering my own question...

It really does look to be a failure of the 12V isolated DC/DC. I took a 12V AC ATX power supply and connected it across the isolated output of the 12V and the motor went round.
Could still be a problem with the input, but I doubt it.

Pretty strange. I would expect the MTBF on those parts to be long and I don't think that is suffered any abuse, overvoltage, etc. It wasn't even a particularly cold winter.

Awkward part to replace on the board. I think I'll just add an external isolated DC/DC at least until I next have a reason to pull the controller.

Seems that the output of ATX power supplies are isolated. Depending on whether I believe that, I might be back driving sooner than I thought (is there anyone doesn't have a couple of old PC power supplies lying around?).
 
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