EV fundamentals #1: How to read a resolver

[@shaggygangst]

Good idea sir, please continue this series with explaining how the code and hardware works.

[@TrickyNekro]

From my medical equipment repair days, I have come across resolvers that the reference coil is on the stator and the readout is done on the rotor ( they can definitely afford the space there ). Nice stuff indeed, not many people know of them nowadays ( most motor control will actually be done with encoders with an index pulse given from somewhere in the system ).

[@EngineersFear]

Oh cool, so that actually exists then. At least in vehicles and with synchronous motors I have only seen absolute feedback such as resolvers or sin/cos hall chips.

[@IfItAintBrokeStillFixIt]

Thanks for the video. Great idea for this series. Gives us a better understanding of what's going on.

[@seimela]

I hated working with Resolver that encoder ,this video changes my attitude

[@EngineersFear]

Great 🙂

[@mehmetcx]

Great explanation Johannes. Please keep going to make videos just like this:)

[@Good-Enuff-Garage]

This is some wicked smart shit! I don't understand any of it, but respect those that do, ha ha

[@JPetr94]

Literally exciting topic :)

[@juiceofsapho]

Very nice video Johan, just keep 'em coming (from one of the nerds)

[@williamPennell]

Great learing module sir thank you...

[@bart5228]

Great video, gives a lot of useful information! Keep them coming :)

[@ut0phya]

Thank you so mutch for these videos.

[@idus]

This was an awesome video

[@andrewcastellanos4237]

This was an awesome video. Could this be used to convert resolver inputs to encoder ABZ outputs? Im thinking of using a stm32 blue pill and some external circuit to do this.

[@EngineersFear]

Probably, yes. AB can be generated with a timer in variable frequency mode and Z by toggling a pin on zero crossings

[@SilasCaze]

This is really good! Thanks!

[@stephendarbey5411]

Super stuff Johannes

[@carlosciturini4918]

Thanks for the video.Let mi suggest a topic : An electrical axis. An master encoder, a slave encoder and an output that control a motor+slave encoder that follow to master encoder in velocity and phase with a low margin de error (< 5 degrees so and so). Thanks Johannes

[@Aaaaaaaaaaaaaamin]

Hi, Thanks for the video. I will be trying to replicate this resolver on TI MCU.

[@vip-zb1nh]

Would like to know about F o C control of pmsm motors

[@EngineersFear]

here you go: kzbin.info/www/bejne/bZC4daxrha90btk

[@chromebooksl4626]

Johannes, could you please share winding schemes of resolver, and drawings or sizes of stator and rotor ? as I remember rhis type of resolver (with this type of rotor) named Verner ?

[@EngineersFear]

Will see what I can do, got one resolver left over

[@elmnaoirfer3751]

If we set 7 volts in the primary coil, what will be the peak voltage in the cosine coil at angle zero Is it 7 volts or less? The rule to find out the peak voltage at angle zero is as follows (peak potential of the cosine signal = voltage on the input coil x cosine of angle sita) (V cosine=Vr x cos cita)

[@aravinds123]

Superb video. Thanks for the in depth walk through!! Looking for more in this series. Btw, just a basic question: why are there many coils when there are 2 output signals and 1 input? Are they connected on parallel?

[@EngineersFear]

To be honest, I have no idea. It is 4 pole pairs (1 physical turn yields 4 electrical), thats probably got something to do with it

[@tobybee]

According to my understanding they are connected in series. The one in the middle is the Tx and the right one next e.g.the sine coil and the one left to the Tx is the cosine Winding. However, a 4 pole pair should have 12 cool systems instead of 10 :/

[@pusatberk4193]

what is the library that you are using for stm programming ? Thank you.

[@isaksoderlund5640]

I really liked this. When the leaf inverter chip is released could you make a tutorial for that as well?

[@EngineersFear]

Thanks! Yes I can make an installation video

[@konstantin88181]

Hello! Is this board "Main board V3" capable of handling prius gen 2 inverter coupled with any toyota PMSM motor with resolver? Thank you!

[@EngineersFear]

The exact combination has not been tested, but yes the board can handle resolver and the software can handle PMSM. Both tested with Nissan Leaf hardware

[@konstantin88181]

@@EngineersFear Cool, I'm now in the middle ow hard desigion what to buy for prius gen 2 inverter. Another last one question: are two boards capable of handling two inverters(inside prius inverter case) in parallel to drive two similar motors(tesla-like 4WD) or one board can handle two inverters at the same time? Thank you!

[@EngineersFear]

@@konstantin88181 Yes you'd need two controller boards

[@konstantin88181]

@@EngineersFear I've already came to same conclusion because the board needs to get a feedback from a motor. And feedback from two motors will be different. Thank you!

[@alank.3519]

Thank you for this excellent and informative video, Johannes. Please would you consider expanding the code to handle synchro resolvers which have three secondary windings connected in a Y configuration? Otherwise, it is necessary to convert the 3 phase synchro signal to a 2 phase resolver using a Scott-T transformer (difficult) or equivalent solid state converter. Thank you again 👍

[@EngineersFear]

You're welcome. It's targeted to EV motors and those don't seem to use synchro resolvers. Sounds like you need something like a Clarke/Park transform for that. It's open source, give it a shot ;)

[@david-ek3uo]

Can i conect a synchro of 400 hz to 60 hz????

[@JamieJones1985]

Is there a way to determine the resolver pole pairs count?

[@EngineersFear]

In the picture you see that the core has 4 lobes = 4 pole pairs. But I haven't seen enough different resolvers to be sure it's always that easy.

[@JamieJones1985]

@@EngineersFear Thanks, I'll go with that to start with, mine appears to be 4 pairs by that reasoning too. openinverter.org/wiki/images/d/d1/20201124_214308.jpg

[@anthonygee9509]

Functional safety involves correct component selection, electronics/system design, as well as software development. Safety doesn't seem to be covered in any of your videos or inverter designs, which is worrying because an incorrect torque could cause a serious accident.

[@EmyrDerfel]

The fan noise in your office is quite intrusive. A lapel mic should avoid this.

[@EngineersFear]

Yeah sorry about that, it was a digging machine

[@EmyrDerfel]

Sorry, I meant when you were showing the sourcecode, it sounded like the computer's CPU fan.

[@EngineersFear]

Oh ok, yes that's possible. Will take care of it

[@EngineersFear]

Indeed, when I was editing the video the fan was going so I didn't realize it was on the recording also

[@anthonygee9439]

I see no mention of functional safety. Have you at least tried to meet any safety standards, and if so, which ones and how?

[@EngineersFear]

Well I do check for minimal amplitude. Otherwise I suggest you check the recent code on github