Ah, no, sorry. The inverter itself is fairly dumb, and will do what it's told (if kept happy with power, enable lines etc I think it'll try protect itself from over temperature too? not sure). Probably safe to treat it just as the 'power' module, with most of the brains in the openinverter board. The 'start' line being held high will be telling the OI board to keep trying to go into 'run' mode (ie, do all the precharge etc checks, and then start pushing pwm in response to throttle etc)MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amI see.
So that starts the inverter, not the control board.
My understanding is that the OI board reads the current sensor inputs on startup and assumes that whatever reading it sees is zero amps (a reasonable assumption probably - the contactors should be disconnected, so no HV. This may not be true if the system has just rebooted in a moving vehicle of course...) but if that '0 A' reading is too far away from 1.65V, it'll throw a "high current offset" error/warning (because the further away from 1.65V, the less 'range' and/or resolution is available). I think (but have not yet tested myself) that the Prius gen2 current sensors have (two, independent) outputs centered on 0V, swing both positive and negative. So need to supply the sensors with 1.65V as their 'ground', and then a simple potential divider on their output to keep the swing within 0V - 3.3V for the OI board. The 1.65V may be ok as a potential divider from the 3.3V supply, but might need to be more robust - using an opamp to buffer the voltage. Need to look into this (if you want to use the current sensors)MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amMight be why my current sensors are angry occasionally. That or, if left at 0v, when it's expecting 1.65v center, must look like a maximum negative voltage.Also bear in mind that with inputs disconnected (left floating) you'll be reading noise. Sometimes it'll look (to the main board) like all is ok on boot, other times it'll 'read' high currents, low HV, weird errors... With the main board powered but the inverter not powered (with 12V) you'll also get screwy inputs from internal resistances, capacitors charging/discharging...
Sounds goodMattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amI've been using a flying lead out of laziness, and, leaving it connected. So, I'll just leave it disconnected until needed.[*]Make up a minimal set of connections between board and inverter (put 'start' on a momentary switch, or leave a flying lead so you can touch it to 12V
No, sorry. the OI board has some inputs that disable PWM instantly without any software intervention. Argh! The through hole board does not have these! Sorry! And I also missed some other connections you'll need... see belowMattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amDumb question... What are the hardware safeties?To start with, you want power and ground connections, and connect all the HW safeties to 12V.
You mean the pre-charge? Just connect that terminal to ground instead of MNC (main contactor)?
You could bypass the diode (put 12V on one of the 12V outputs) but 11.3V should be ok if it's fairly 'solid'.MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amI got a 12v 5a power brick last week to replace my 1a bench supply. But I notice, presumably due to the polarity protection diode voltage drop, I only get 11.3v on stuff now. I am apparently making everything more difficult with low voltage. I'll grab a lead acid instead.[*]Get the inverter and main board powered up with 12V (a car battery is fine, especially if that's plugged in to a charger too just to keep it topped up during testing - a low 12V will make everything more difficult).
Just refreshing the displayed values on the web interface - just confirms that the web interface can pull some numbers from the OI board, and that some of these numbers (udc, throttle maybe, any analogue inputs) will change a little with noise - the actual changes will depend on local conditions and calibrations, don't worry too much about it is all.MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amRead which values specifically?[*]Read values. You will get, generally, some noise on all the inputs.
What inputs?
What should be expected for values or noise?
What am I doing with this information? What does it establish?
I think, at this stage, ignore the current sensors for now, and just make sure you can get PWM and drive a motor. Johannes' solution will be the most likely to work, but there may be simpler ways, but this isn't what's holding you back (yet)MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amI get the gist of it, but not in a way I'm confident to act on. Plus, I would like the current sensors to work, so, an actual solution would be best.[*]As above, you don't need to, but I would be tempted to get an approximate calibration of the current sensors, if only to get rid of the warnings on the interface. But this may need some potential dividers etc (I don't have a gen2 board, but the schematics are on the wiki. The stm32 will be expecting an analogue voltage of 0-3.3V, with 1.65V resulting in a 0A reading. I think you would need to provide an external potential divider to convert the output from the current sensors to these levels. Plus it's generally more tricky to feed a fixed current through a sensor. But as above, not essential for sine firmware
Digging up from this thread, Konstantin plagiarized Johannes' solution on his Gen2 board, but, that's a bit too complicated for me: viewtopic.php?p=11441#p11441
Arber discusses it somewhat (centering on 2.5v instead of 1.65, corrected/discussed later), and verbally describes the process: viewtopic.php?p=9031#p9031
Just below, Sirrocco links a calculator (referenced several times with annoyance in the future), that I'm sure works, but no one seemed to have success actually picking the right values with: viewtopic.php?p=9043#p9043
People post the circuits they tried that didn't work or that they struggled with, but don't document their proper end result. So, if an end result was reached, everyone reinvents the wheel regardless.
Again I get the gist of it, but, I only somewhat know what an OpAmp is, I don't think I have any in my salvaged parts pins (maybe I do, I don't know the common part numbers), I don't know exactly what to order, and shipping is so expensive I kinda want to order all my next batch of electrics at the same time, not 2 op amps.
Do you have the pwm lines from the OI board connected with the inverter at this stage? I was aiming to check the OI board outputs with the inverter (and HV) disconnected) But either way...MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amWell, something is happening.[*]You should now be getting pwm from the board pwm outputs. Ideally check with an oscilloscope, but a multimeter should be able to see 'something' happening (maybe also read frequency)
However, my HVDC is fluttering all over the place. It was at 100v, but it's fluttering between 5v and 50v. This is right off the variac's supply's DC terminals.
It's only a 3amp variac, and my smoothing cap is only 47uF (what I had around), so, maybe this is suffocating the smoothing capacitor a bit? Shouldn't be, the inverter's main power cap should basically be in parallel with it, no?
Are you reading voltage with a multimeter or is that from a built in voltage reading on your supply? You may find that EMF from the inverter does some interesting things (touchpads on laptops can be quite susceptible and behave strangely sometimes while the inverter's switching ) With no current drawn from the HV supply, there should also be no voltage drop, no matter the capabilities of the supply. And yes, the main cap should be doing plenty to smooth any draw.
The inverter should only switch if it has power, you're sending PWM to one of the motor inputs (MG1 or MG2) and you're sending 12V to MG1 or MG2 (or both) enable pins - 14 and 25 on the 32pin connector I believe.
Parallel? Connect the filament bulb in series with your HV. With no current through it, there'll be no voltage drop across it, and it won't light. If lots of current flows through it (short circuit, fault, trying to drive a motor etc) voltage drop across it will increase, limiting current (hopefully preventing any damage) and it will illuminate (a nice visual feedback of 'current flowing').MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 am ... I connected a lightbulb in parallel with the HVDC output. It's on, and steady. But the same terminals it's connected to are wandering hugely.
Good, some the board and web interface are working and accepting commands at least!MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amWell, fwiw, voltage stabalized back at 100v.[*]Send a 'stop' command
Excellent, gotta be a good sign!MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amIndeed, they are.[*]Yes, that set of parameters does include udc offset and gain (which are hopefully pretty close to what you've got).
Ah well, no odds. Still getting weird effects from your HV voltage reading?MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amOops, had those from the start...[*]Now connect up the PWM outputs on the board to the PWM inputs on the inverter
Oops, had it at 100v the whole time.[*]Connect some HV (direct to the bus is fine, highly recommend some current limited supply - either a bench PSU or similar, or a battery with a filament bulb or oven element connected in series. You don't need massive voltage, 12V will do)
~8kHz from memory, and not particularly loud.MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amIt might be so high pitch that I'm deaf to it (I've lost some upper range), but I don't hear anything.[*]The inverter should be making a whistling noise - this is the IGBTs switching
GoodMattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amMy kill-a-watt knockoff says it went from ~5w on the variac input to 7w with no bulb on the HVDC, just the 3 on the phase outputs. So, sounds good.[*]With nothing connected to the inverter, you should have 0 current on the HV line (any bulb shouldn't be lit). If you have significant current, you have shoot-through (+ve and -ve IGBTs turning on simultaneously) which should be impossible with the gen2 inverter...
Yes, bulbs should work fine. I guess they're a good visual, and naturally limit current, so a good test (compared to a motor, which does nothing until it suddenly starts spinning and throwing itself around the bench... good point )MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amI'm too chicken, can't I test with the bulbs first and see them, I dunno, power up and flash around?[*]Motor next. Connect it up!
I'm not certain what use there was in having the bulbs in there. Just to be a litmus test for whether current would be flowing through them (bad) or not (good)?
Hmm, that's a shame Voltage on the outputs is good, perhaps it just wasn't sending enough current to light the bulbs (ampnom)? Did you see any movement on your killawat?MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 am I tried the first part of the motor procedure, spinning at 10hz with the lightbulbs... I could see a warbling voltage on the phase outputs, but no power was ever drawn to the bulbs.
Sorry, I forgot to mention udcmin. Not sure if 'manual run' checks that, but setting it really low is another potiential obstacle out of the way. Output voltage may have disappeared due to the low impedance of the motor (compared to the bulbs), especially with the lower HV? As above, try increasing ampnom?MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 am...[*]Power up, start, set fsplispnt/ampnom. You should be able to get the motor spinning by adjusting ampnom and fslipspnt - see the wiki. This may not work if your HV supply is too weak, but hopefully you'll at least be able to feel something while spinning the shaft by hand
Whelp, I lifted the motor up to the desk, removed the lightbulbs, and powered the HVDC off of a car battery (with narrow leads I could grab to disconnect as "fuses"). I can measure 12.6v on the HVDC inverter input terminals... but nothing happens. Nothing happens when it's supposed to be spinning at 10hz. No voltage on the phase outputs (so, it's not just that it can't move the motor, nadda is being sent). Twisted the shaft with my fingertips, can't detect anything different than off.
Tried setting my "udcmin" to 10v. No change.
Far as I can tell, nothing different with the setup than when I had the bulbs instead of the motor phases.
Disclaimer - I've not played with an induction motor.MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 am Following the wiki ( https://openinverter.org/wiki/Schematic ... _the_motor ), I'm not sure how to apply the context of the motor I'm using.
"'So for a DC bus voltage of 350V, a nameplate frequency of 60Hz and a nameplace voltage of 200V you get fweak=60Hz x (350V/1.41)/200V = 74.5Hz"
My test motor is the smaller of the two ACIMs from a forklift.
It says:
Now, my DC bus, is that my test bus? Do I have to keep changing this every time I change my test setup?
Else, let's say DC bus is 100V.
Nameplate frequency is 85hz.
Nameplate voltage is 33vac.
So...
"fweak" = 85hz x (100v / 1.41)/33 = 363.2hz?
... but do I care what my namplate voltage was? Since, I'll be running the forklift motor at, I dunno, at least 200v?
Likewise, do I care what nameplate frequency was?
Or, is this exactly the purpose of this configuration - that we'll be running motors at way higher voltages than spec and need to account for that?
... Doesn't really matter, since even the simpler 10hz spin doesn't work.
So, back to basics (and apologies if you know all this!). With a DC brushed motor, a particular motor will spin at a particular speed when connected to a particular voltage with no load. That speed is determined by the applied voltage, and the construction of the motor (characterised by 'Kv', rpm per volt). Kv is affected primarily by the magnetics in the motor. An example - two identical 'perfect' (no friction etc) motors, but one has stronger magnets inside. Apply 12V to each, and the motor with the stronger magnets will spin slower. A spinning motor also simultaneously acts like a generator, and when not under load, will accelerate until the back emf generated by it spinning equals the applied voltage (hence no current flows, so it stops accelerating and continues at it's current speed. A stronger magnetic field produces a higher emf for a particular speed, so it reaches that equilibrium at a lower speed.
AC motors are "the same", just commutation is done electronically instead of mechanically. So, for a particular HV DC bus voltage, even if you have direct control over the frequency, the motor will only spin so fast (and probably fail to run if the frequency is too high). Like you say, you're supplying a much higher voltage, so you'll be able to get a much higher speed out of it And we can also do some more magic - by applying current to the three phases in a particular way, a component of the resulting magnetic field will actually counteract the magnetic field from the stator (which is, in turn, induced by the magnetic field from the rotor.... I said 'magic' for a reason, my head hurts!), so effectively weakening the internal magnetic field, increasing the Kv of the motor, so it'll spin even faster! This is field weakening. If you don't need the motor to spin faster than its 'base speed' (DC voltage x Kv, but you also need to account for load) then you don't need to worry about field weakening, but it will help at higher speeds, and that's what the wiki is taking you through. Those parameters do change based on the HV voltage, but you also set a 'udcnom', which is the bus voltage you're using to set these parameters, and the OI board will adjust those as the HV voltage changes.
SorryMattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 amNope, never got a motor to spin.[*]Hopefully by this point, you'll have confirmed that the board and inverter are both working and capable of spinning a motor. And gained a bit of confidence?
[/quote]MattsAwesomeStuff wrote: ↑Thu Apr 21, 2022 8:46 am Confidence? Ehn, just in the certainty of having less vague instructions, yes, that helps a bunch. Haven't made much progress otherwise.
I could rig the variac to spin the motor, but I'm still to chicken to try it, if the 12v didn't do anything.
Thanks, btw, you and others, for taking the time to assist.
I think you're nearly there,and might get light bulbs 'spinning' (or the motor of course) with a bit more ampnom. I'd aim for a low frequency (the slower it is, the easier it is to see the 'spin'), and gradually increase ampnom. I don't have exact numbers for you, as I didn't use lightbulbs and went straight onto a hacked up alternator motor, and on a different inverter... but with a 24ish V 'HV' bus (two car batteries in series) and think I was getting movement around 10 - 20 ampnom. But it will depend on the inverter, your HV bus voltage, what lightbulbs you're using... try changing ampnom and seeing what happens. Worst you can do is max out your variac