I have strange issue in my small EV vehicle for child (my project) , after few minutes drive motors reach temperature around 57 degrees Celcius motors and stop working or change directions or other strange behavior appear. These are BLDC motors with Hall sensors and optical encoder. Motors driver exclude becasuse I made swap for second "cold" motor driver and issue still apear.
Motor stop working after warm up
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If the halls are installed in the motor windings or right next to them as usual, they may heat up more than the temperature sensor (if it's not also mounted there), and get hot enough to give incorrect position signals, which will cause various behaviors including those stated. "UVW" hall sensors are usually setup this way, with this type of issue during overheat.
It can also be a connection problem, where it heats up enough to push any part of the circuit connection apart enough to cause signal problems. Usually cold does this more than heat, but it can happen with any change in temperature that causes materials used in the connections to expand or contract. It can be at the hall sensor itself with a leg broken off the sensor but held in place by the wire, or a wire broken at a contact or bend, or even inside it's insulation somewhere (probably inside the motor near the windings), etc.
If your controller can use the optical encoder instead of the hall sensors, you could try that and see if it still has problems.
It can also be a winding failure, damaged winding insulation so that as the heating metals expand it shorts to the stator lamination, etc., and interferes with the phase currents from the controller.
It can also be a connection problem, where it heats up enough to push any part of the circuit connection apart enough to cause signal problems. Usually cold does this more than heat, but it can happen with any change in temperature that causes materials used in the connections to expand or contract. It can be at the hall sensor itself with a leg broken off the sensor but held in place by the wire, or a wire broken at a contact or bend, or even inside it's insulation somewhere (probably inside the motor near the windings), etc.
If your controller can use the optical encoder instead of the hall sensors, you could try that and see if it still has problems.
It can also be a winding failure, damaged winding insulation so that as the heating metals expand it shorts to the stator lamination, etc., and interferes with the phase currents from the controller.
Photo how looks hall sensors, I have hall sensors and optical encoder. Can heat affect the optical encoder ?
Controller set to the optical encoder but I think hall sensors also are used. These are low rpm motors 0-200 rpm
It can not be connection problem because I have 4 motors and all have this issue unless all have manufacturing defect.
Controller set to the optical encoder but I think hall sensors also are used. These are low rpm motors 0-200 rpm
It can not be connection problem because I have 4 motors and all have this issue unless all have manufacturing defect.
Heat can affect anything, but if your temperature is only 57C, it's not normally enough to affect the electronics--most things are good to at least 70C. To know if the heat you see can affect the encoder, you'd have to look up the parts on it to see if you can find a spec sheet for them, to see what their limits are.
If the encoder is not located near the winding, it is unlikely to be affected as early as the halls are, if it gets affected at all. Where is your encoder located?
The problem with the hall sensors vs heat is that they are embedded in the motor's metal right where current flows and creates the heat buildup, so they may be hotter than the average sensor temperature (which appears to be the black wires leading off the top right of the hall board, probably glued to the windings). Depending on how often the readout for temperature is updated, it might miss the spikes of heat made by the windings, but the buildup of heat in the motor's metal core continues, and will eventually spread the heat everywhere in the motor. But you might be having the problems before that can happen, and so never reach the point at which the higher motor core temperature reaches the sensor for the display (or does so after you stop checking it).
I don't know why a controller would use both types of encoders. Optical encoders should be higher resolution and better able to determine motor position and so better able to drive motor based on that. You would need to check the controller manual for how it reads and applies sensor inputs, and switches between them, to know if this is something that it does, and how to bypass it to prevent the problem.
If the controller is typical, it should only have one kind of sensor connected to it, so that it only gets one set of readings. If it has both, perhaps a problem could be that at some point it gets confused by multiple inputs (though I don't know why it would only happen once it reaches a certain temperature).
Below link to site with manual and software for motors controller. Poor support and instructions, there are a lot things what I can not understand in the programming software . I spent a lot of time to set up only to motors starts running. Now at cold motors working pritty good but not after warm up.
www.uumotor.com
multi-function RS485 CAN encoder hall sensors brushless dc dual control driver
Model: SVD48V30A, SVD48V50A Price USD160-180 RS485, RS232, CAN, PWM, analog inputSV-Config programming software, RS232 interface A/B/Z type, A/B+HALL type, Hall sensor type . SVD48V30A price is USD…
www.uumotor.com
I do not have oscilloscope and I used logic analyser. I am wondering about distortion on the signals from hall sensors even on the cold motors (I can not compare to others motors maybe it is normal when use logic analyser ). Distortion are also on the stopped motors. When supply to motors are off and motors rotate by hand no distortion even on the warm motors. Now question motors driver problem, poor hall sensors or other. After warm up distortion are a lot more than on the cold and that is why problem appear at strange 57 degrees Celsius
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Noise in the hall signal lines is common, and comes from multiple sources. it can come from the fields in the stator itself, but it's more commonly induced from the phase wires that are usually paralleled in the cable from motor to controller.
Sometimes a fix is as simple as physically separating the hall and phase wires for as much of hte length as you can between motor and controller.
Sometimes it requires shielding the halls (and their power and ground), and ground the shield only at the controller end.
Sometimes it requires twisted-pair signal+ground wires for each hall signal.
Sometimes a 0.1uf ceramic capacitor on the hall power supply, at the motor end, may help with supply noise. If the motor max RPM / pole count is low, then you can add these on each signal line...but the higher the RPM the smaller the cap has to be to keep it from interfering with the controller getting the real hall signals, and the less noise spikes it can absorb.
Sometimes if the controller supports it (or can be altered to do so) you can change the pullups in the controller to be powered by 12v instead of 5v, so there is a greater signal-to-noise ratio; this makes the hall "off" signal 12v, and the hall "on" signal grounds the 12v to bring it to nearly 0V, so there is a much greater swing from on to off. Doing this modification probably requires a signal buffer inside the controller between the now 12v-range signals and the still-5v MCU inputs.
Sometimes a fix is as simple as physically separating the hall and phase wires for as much of hte length as you can between motor and controller.
Sometimes it requires shielding the halls (and their power and ground), and ground the shield only at the controller end.
Sometimes it requires twisted-pair signal+ground wires for each hall signal.
Sometimes a 0.1uf ceramic capacitor on the hall power supply, at the motor end, may help with supply noise. If the motor max RPM / pole count is low, then you can add these on each signal line...but the higher the RPM the smaller the cap has to be to keep it from interfering with the controller getting the real hall signals, and the less noise spikes it can absorb.
Sometimes if the controller supports it (or can be altered to do so) you can change the pullups in the controller to be powered by 12v instead of 5v, so there is a greater signal-to-noise ratio; this makes the hall "off" signal 12v, and the hall "on" signal grounds the 12v to bring it to nearly 0V, so there is a much greater swing from on to off. Doing this modification probably requires a signal buffer inside the controller between the now 12v-range signals and the still-5v MCU inputs.
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