tndr_1 said:
Okey... So maybe I need to pause my query a bit... You have to teach me this...
The reason is that I want to see how much current the motors draws and from what I can understand that value is not the same as what the ESC draws?
Phase currents can, depending on the load the system is under at that moment, and the system setup, be much higher than the battery currents. But the average voltage is lower at that time than the battery voltage, so the total power is equivalent (minus the losses in the controller due to efficiency of conversions).
Is there is a specific need to know an exact phase current at any particular moment under a specific load (because it won't just be one current value)?
The only easy way to measure the phase currents to the motor is to use a motor controller that actually already has current sensors built into the phase outputs, and directly monitors these for motor phase currents. Any FOC controller should be designed like this; few others will be, if any.
Then for you to access that data, the controller has to have a way for you to connect to it in realtime during use (not just a setup program), either cabled or wirelessly, or with it's own display, and have access to those data.
IIRC the VESC in general will do this, and has software you can use for it to see most info about the system. There are numerous other FOC controllers but I don't know which ones give you access to the data you want. The Phaserunner / Baserunner series should be able to do this; it's likely the ASI controllers they were based on could also do it, but from reading posts about ASI software, it's not easily accessible (requires passwords for various levels of access that you can only get from ASI and only if you buy directly from them). There are also high-end controllers that can do it but they're all OEM-only (some like Sevcon you can buy but you can't get support/etc from the companies on using them or setting them up, and for those it's a very complex tuning process).
The catch with all the FOC controllers I'm aware of is that all of them need to "know" specific things about what motor they're driving; autotuning exists in some of the controllers but it isn't perfect, so you may then need to manually tune the controller further for that motor to make the system run correctly. Those without autotune will need you to input the motor specifics (which are not provided with most motors, so you have to test for these, making things even more complicated in those cases
).
Alternately, you can build an arduino (or similar) system that reads current sensors (usually hall-based sensors, rather than shunt types; see the various motor-controller design threads on good sensors to use for this) you would install into at least two of the phase wires between motor and controller. Then program the MCU to read those sensors and display the data for you (or record it for later readout).
I don't know any good way to accurately read the phase current between motor and controller with any of the typical meters you might have--the ones that do read AC are not really intended to read the kind of waveform these have, so I don't know how close the measurement result might be to reality, especially since you need to read current in at least two of the three phases at the same time to accurately tell what is going on between motor and controller (and then do some math to determine the "real" current; this is what the FOC controllers do).