Cooling Fan Active and Sevcon Configuration

 Cooling Fan

A cooling fan from Thunderstruck (Full kit) was a quick way to assure the liquid cooling of the ME1616 motor was providing maximum benefit.   A liquid cooled heatsink was also installed under the Sevcon Gen 4 controller to protect it from thermal issues.  

Wiring

A standard 12V relay was installed on pins 7 & 8 on the Sevcon controller to switch the 12V (car 12v) supply for the fan.  The coolant pump was permanently wired to the 12V supply to run continuously while the ignition is on.  The theory is the fan does not need to run unless the motor is getting too warm.   I may install a DC Speed control on the fan to slow it down and reduce its sound level, but I'll have to see if the reduced cooling creates any issues.

Sevcon Configuration

As expected, the Sevcon settings took longer to figure out than the mechanical or electrical work.  Here are the settings to make the fan work.

• Input/Output (tab in Helper) Local Contactor Outputs:  Contactor 2 = Not Mapped, even though there is an option for Traction Motor Cooling Fan.  If this is mapped, Pin 7/8 will be energized whenever the controller is in Operational mode, regardless of the Fan Settings.
• External Heat Sink Fans 0x5A01 or 5A01h:  This is where the temperature set points are entered.  I ended up setting the Fan Temperature Source to Motor Temperature Sensor and raising the limits to 45C(on) & 35C (off)
  
• Analog Output VPDO Mapping 0x3200 3200h:  Other documentation says that Output 2 should be 0x2421 (cooling fan status).  I found Output 2 should be 0x24ff.  0x2421 is read-only and always shows 0x0C00 as a value.
• Analog Output (Contactor Drive) 0x6C11 6C11h:  Here you can change the output voltage of Pin 7/8 by changing the values for Analog Output 2.
• Analog Output Current/Voltage Mode 0x46A1 46A1h:  This controls whether the pins are voltage or current controlled.  This is set to 0x0 to set all outputs to voltage mode.
• Note: I attempted to measure the voltage across Pin 7 and Pin 8 before connecting the relay.  It showed almost battery voltage even though the controller was showing it outputting 12v on the Local IO Monitor on the Main tab of the Helper.  Once the relay was connected, it read 12.5v.  I suspect the voltage control circuit needs a small load to operate correctly.

After some initial testing, the controller turned the fan on at 45C and turned the fan off once the motor had cooled to 35C.

Here is the current working DCF (Sevcon Gen 4 Size 4 with Motenergy ME1616) file for reference.  LINK  This config also addressed many of the PMAC gain settings.  Seems to be very stable and drivable in 3rd gear.

Gearbox Ratios

Gearbox Ratio - CV Joint  - Erratic Encoder

 Here is a handy calculator to help map between RPM and MPH.

Guessworks - Gearbox & Speedo Ratio Calculator (guess-works.com)

Settings: 165/70 x10 wheels; 1:1 Drop gear ratio, MKIII Cooper S gearbox, 3.444:1 Final Drive

For Jan, this is what it calculates which has been verified using a GPS speedometer.:

Given this, with the ME1616 motor, 45 MPH is easily hit at about 5,000 RPM, well within spec.   Field-weakening is active at these higher RPMs but the responsiveness is decent. from about 20 MPH up to 45 MPH.

Currently just staying in 2nd gear for most city driving, though 3rd gear is quite acceptable and allows speeds up to 60 mph.

Configuration learnings:

1. Low Speed Gains and Speed Mode Gains play a big role in low (below 150 rpm, which is adjustable) performance.  If these gains are too low, the motor is very sluggish starting out but once over the 150 rpm threshold, the primary gains Kp and Ki for iQ and iD become active.  With the Low Speed settings were low, it was taking ~2 seconds to go from 0 rpm to 150 rpm, which is a long time when the traffic light turns green.

2. Observing an electrical hum at low RPM which started once I increased Kp and Ki for iQ and iD.  No obvious side-effects, but audible.  - This is from Kp for iD being set to 8.  Lowered to 2 and hum resolved.

3. Added a cooling fan to the new radiator.  Wired to the same fuse as the one activating the high voltage power (not traction) feed to the Sevcon controller.  This created some noise, and the controller issued a parameter out of range fault, and the Find the Parameter feature identified the Temperate Map Setting #3 as being the issue - It was set to 110C and 0.5 cutback, which should have been well within range.  Disconnected the fan and the fault code resolved.

4. Controller was going in the Motor Temperature Cutback at 80C, though the mapping did not start until 100C.  Tried different mappings but no change.  Activated and deactivated the I2T motor temperature feature and this resolved the issue.  I2T is deactivated and now the motor thermal cutback is operating properly.

5. Receiving Encoder Errors (0x52C1) when coming to a stop and the car rolls backwards a little.  It seems like the error is set (requiring a restart) as soon as the throttle is pushed.  Added shielding to the encode lines to see if helps but did not.  Swapped the encoder with one from another motor I had, and it appears the encoder errors are resolved.    Drove about 6 miles with stops and starts and the motor up to about 80C and not a single encoder error

6. Inner CV Joint alignment.  When the new ME1616 was installed, its increased size shifted the transmission a bit.  Also, the new motor provided an opportunity to realign the transmission.  Well, the first attempt had the transmission about 1/2 inch to far forward.  To shift it back, the transmission had to be raised about 1/4 to allow the motor to avoid a bolt from the suspension tower.  This allowed the motor whole assembly to shift back the 1/2, resulting in a much better alignment of the left inner CV joint.  In looking at the CV joint, the ball bearings were not fully within the joint and under force (like pulling up a driveway), would push out of the joint, slipping, and causing a thump sound as they pushed back into the joint.  With the improved alignment, they now are more in the joint and unable to push out.