openinverter forum

While testing my inverter in manual mode I've noticed the motor will stop running after some random amount of time has elapsed. When I investigate I find that 2 parameters have lost their values. The two parameters which are losing value are fslipspnt and ampnom.

While testing I set the values of fslipspnt = 10 and ampnom = 60. When the motor stops I check the values and they have changed to fslipspnt = -1.62 and ampnom = 0.06.



When I check the errors sometimes an error is reported with no error message, other times there are no errors recorded.



I can reproduce this same failure many times after resetting the parameters, and even after disconnecting power and powering back on. The parameters always seem to return to these same values.

Have I corrupted the firmware?

fslipspnt and ampnom are calculated by the software according to the throttle level when you are running the inverter in normal mode. You are currently running the inverter in manual mode and your keyboard is the throttle now. These values are not stored over power cycles so you have not corrupted the firmware.

First, you should understand the "fweak" parameter. It's the frequency point where your inverter can send the maximum possible voltage from the batteries. It's a stored value and specific to your motor.

fslipspnt determines the stator winding frequency. For example, if your rotor is spinning at 100Hz, your inverter will send (100+fslipspnt) Hz to the stator. Slip is proportional to the torque, but up to some point. It's calculated momentarily for the throttle value.

Ampnom is the relative amplitude, when 100 it applies the maximum possible voltage according to the current frequency and fweak relation. It's also calculated momentarily for the throttle value.

The empty error message is odd.
Which version are you running, which opmode and what is the approximate time after which the motor stops?

Firmware version is 4.00, opmode is 2.

The time at which the motor stops running seems random. It has stopped in as little as 8 seconds, and sometimes it has run for longer than 10 minutes.

While the motor continues to run I've noticed that the values displayed by the web inteface match the values I've set, but if I download the json parameter file the values in that file are the odd values which the device seems to revert to after some random time has elapsed. After the motor stops the web interface values match the downloaded parameter file values.

Notice the values of fslipspnt and ampnom in the json do not match the values as displayed on the web interface.


Maybe I will try to upload the latest firmware version and see if this resolves the issue.

What are you using as the power supply to power up your inverter? Through a 12V battery, or a lab PSU? Is it possible that your inverter is reset due to a power loss? As I mentioned in my previous post, fslipspnt and ampnom values go back to their default state when the inverter is reset because they are not stored. To make sure that this issue is related to a power loss, there are many ways but the easiest I can think of right now is this:

First, set dirmode=0 and save. This will make the direction selection through a 12V pulse instead of constant 12V. Then, apply only a 12V pulse to the forward input and disconnect the direction signal. Make sure when you type "get dir" the response is 1. Then, set fslipspnt/ampnom and let the motor run. After the motor stops (by itself, randomly as you described) type "get dir" again. If it's 0, it means your inverter is reset due to a power loss.

I have been powering the inverter with a bench top power supply. I'm still working to get all the parameters dialed in and I don't yet have a throttle pot connected. I suppose there could have been a momentary power loss.

The last troubleshooting I did was downloading the parameters as json, then editing the fslipspnt and ampnom, then uploading the parameters back. After this my inverter no longer stops randomly. I've run it several times for 20 minutes continuously without a stop.

EDIT:
Whatever the issue was it seems to be resolved now. Thanks for the help everyone!

I guess with that comment I jinx'd myself. I had the issue again. Possibly it is caused by adjusting the ampnom value with set commands while the inverter is running?

This time I also received the error:
[501]: DERATE - TMPHSMAX

Is this max heatsink temperature? get tmphs shows 30.62 which shouldn't be too high

Also the fslipspnt and ampnom parameters did not change. I was able to restart the motor immediately. However after a few more minutes running (less than 5) the motor stopped running again. This time with the fslipspnt and ampnom parameters corrupt with the same values I've shown above.

I think this is somehow related to getting/setting parameter values and refreshing the web interface page while I have the inverter running. When I leave it running and do not issue commands to the web interface it runs continuously for long periods of time.

You get the TMPHSMAX derate message when the measured tmphs goes over 85 celsius. It's a hardcoded value and cannot be changed, AFAIK. It doesn't actually stop the motor, just derates the slip by a factor of 50%. If you're measuring the tmphs as 30, I guess you're suffering from bad wiring and getting momentary spikes/disconnections.