**The Challenges of Building a DIY BLDC Motor Driver**
The solution here was to start with a lower voltage and give the motor a spin to get it going. And as you can see by increasing the voltage, the speed does increase as well and I have to say that you can in fact load the motor a bit before it gets stuck. But of course when it is stuck it is not that easy to start it again. So the first test was definitely not optimal because you have to keep a close eye on the applied voltage and current, the motor can get stuck and it surely does not start on its own. But maybe using a small motor is not recommended because in the video the creator was using a way bigger one and there it started on its own.
To try that though I needed to convert a 3 wire BLDC motor of mine into a 4 wire type which was certainly not easy because the individual coils were wrapped into one another and thus I wasn't 100% sure which one was which. But in the end I apparently assigned them all correctly because the motor still worked just fine with a commercial ESC. And that means it was time to hook it up to the DIY driver. Once again first try at 9V and yes this motor also didn't start on its own. And pretty much the same problems as before do apply to it as well meaning it can definitely get a bit loaded but it can also easily get stuck.
So I tried one last 4 wire motor with this driver and this time the motor actually started on its own, but that does not mean that the remaining problems magically disappeared. The reason for those problems and why the driver behaves a bit differently with every motor is of course its simplicity and how it works. As a reference a commercial ESC utilizes a microcontroller to not only start spinning the motor by powering each coil in a specific order. But it also then monitors the induced voltages of the currently unpowered coil to get the exact moment right in which the driver has to switch to the next step and that is called a feedback system which can result in such beautiful motor voltages.
Now the simple DIY ESC also comes with a feedback system but a very dumbed down one. For example here you can see that this gate voltage is only high and thus this MOSFET ON when this drain features a high enough induced motor voltage and this diode does not connect the Gate to GND. This way the motor coils do get powered one after another due to the changing induced voltages but the problem is simply that this all depends on raw unprocessed voltages which do vary from motor to motor. That is why some motors will start on their own because the first current kick will induce a high enough voltage and this raw voltage problem is also the reason why motors get stuck when the values get too low.
So all in all this circuit is more a gimmick than anything else and I didn't even start complaining about the way too high occurring voltage spikes that will destroy your MOSFETs sooner or later. So please do not connect such a circuit to a battery and do not believe in any of those simple BLDC driver videos because they all hide some information. But if you want a cheap and simple ESC then get this one from Aliexpress.
With that being said I hope you enjoyed this video and if you are still wondering why the driver also works with 3 wire motors just as good as with 4 wire ones, then let me tell you that I think that those two current paths are apparently enough. But this MOSFET right here will probably not like that for a long time.
But anyway as always consider supporting me through Patreon to keep the show going. Don't forget to like, share, subscribe and hit the notification bell. Stay creative and I will see you next time.
WEBVTTKind: captionsLanguage: enThis is an ESC aka an electronic speed controller and they are super important when it comes to driving BLDC motors which come in all sorts of sizes for different applications like for example drones, gimbals, electric skateboards and much much more. Basically put BLDC motors are widely used nowadays and the only real disadvantage of them is that they can not be powered directly with direct current like from a battery. Instead we need to put the mentioned ESC in-between motor and battery, whose job it is to connect the motor wires to the battery voltage in a specific order so that the motor can spin.That is why ESCs are so important and you can actually spend a ton of money on them if you need a real powerful one that can handle a big and powerful motor.So as you would expect ESCs are normally not that simple to build which we can easily prove through the number of components this super basic ESC is made of which are 85 in total.And that is why I was rather surprised when one day YouTube suggested me a video in which someone built an „ESC“ with just 9 components. At first sight I of course thought that this was a FAKE but half a million views and a good like to dislike ratio lead me to giving it a try and I was surprised to find out that the circuit does in fact work.So does that mean we should we all abandon the expensive complicated ESCs and simply build this almighty super simple DIY circuit? We will certainly find out in this video! Let's get started! This video is sponsored by MEL Science which is a subscription service that offers monthly science boxes like this one right here about, for example alternative energy. It is a hands-on science experimentation kit designed for kids to make science topics more accessible and simply fun to play with.The experiment instructions are straightforward, easy to follow and you can always dig a bit deeper by using the given AR and VR apps with your phone. So I personally like what they are offering here and I will certainly explore more of their kits which you can all find nicely listed on their website. If you are also interested then use my promo code GREATSCOTT! To save 50% on your first monthly box. Now first off what I love most about such videos is that they do not give you much information. All the creator showed was how he prepared a motor for its circuit, how to connect the components together, he threw in some component choices, showed that the circuit can spin a motor with 9V and finally presented a schematic which for convenience I recreated here. But what was sadly missing and very important was whether the driver can handle when a proper load gets attached to the motor.Because while it is certainly fun just rotating a motor, you pretty much always want to attach a load so that the motor actually full-fills a job. Of course there were more things I was interested in but before boring you too much let's rather build the circuit by firstly gathering the mentioned components. Now sadly I didn't have the mentioned MOSFET types lying around but I think my IRFZ44N here should be a good replacement considering that it comes with similar properties. So next I soldered all the components to one another according to the schematic.After that all that was left to do was simply hooking up a motor which lead to the first big problem.You see pretty much all commercial BLDC motors come with 3 wires but the motor shown in the video and schematic requires 4 wires. Now truth be told though I accidentally discovered that this circuit also works with 3 wire motors and we will have a quick look at that later but for now let's image only 4 wire ones work. The reason for that is that the MOSFETs act as switches that can only connect each coil of the motor to GND.And if there is no voltage potential then of course no current will flow and that is why we usually need the 4th star point wire that we can connect to the positive voltage so that current can flow. And by the way commercial ESCs do work with 3 motor wires because they have 2 MOSFETs at each wire that can either connect it to the supply voltage or GND and thus we can create all the current directions we need. So without knowing the 3 motor wire secret, this is already one big flaw of the circuit. But to test it anyway we can cheat and get ourselves such hard drive or optical drive motors because some of them come with the exact 4 wires we need. To determine which one is which we can simply measure the resistances between all points and when three of them feature one common low resistance to one then we know which one is the star point. And thus we can finally add some wires, connect the motor to the driver, hook up my lab bench power supply and set the voltage to 9V like in the video. And as you can see after powering it up nothing really works like intended. We got a big current flow which does not heat up the MOSFETs but instead one coil of the motor because the corresponding MOSFET switch is turned on. The solution here was to start with a lower voltage and give the motor a spin to get it going. And as you can see by increasing the voltage, the speed does increase as well and I have to say that you can in fact load the motor a bit before it gets stuck. But of course when it is stuck it is not that easy to start it again. So the first test was definitely not optimal because you have to keep a close eye on the applied voltage and current, the motor can get stuck and it surely does not start on its own. But maybe using a small motor is not recommended because in the video the creator was using a way bigger one and there it started on its own.To try that though I needed to convert a 3 wire BLDC motor of mine into a wire 4 type which was certainly not easy because the individual coils were wrapped into one another and thus I wasn't 100% sure which one was which. But in the end I apparently assigned them all correctly because the motor still worked just fine with a commercial ESC. And that means it was time to hook it up to the DIY driver. Once again first try at 9V and yes this motor also didn't start on its own. And pretty much the same problems as before do apply to it as well meaning it can definitely get a bit loaded but it can also easily get stuck.So I tried one last 4 wire motor with this driver and this time the motor actually started on its own, but that does not mean that the remaining problems magically disappearedNow the reason for those problems and why the driver behaves a bit differently with every motor is of course its simplicity and how it works.As a reference a commercial ESC utilizes a microcontroller to not only start spinning the motor by powering each coil in a specific order.But it also then monitors the induced voltages of the currently unpowered coil to get the exact moment right in which the driver has to switch to the next step and that is called a feedback system which can result in such beautiful motor voltages. Now the simple DIY ESC also comes with a feedback system but a very dumbed down one.For example here you can see that this gate voltage is only high and thus this MOSFET ON when this drain features a high enough induced motor voltage and this diode does not connect the Gate to GND. This way the motor coils do get powered one after the other due to the changing induced voltages but the problem is simply that this all depends on raw unprocessed voltages which do vary from motor to motor.That is why some motors will start on their own because the first current kick will induce a high enough voltage and this raw voltage problem is also the reason why motors get stuck when the values get too low. So all in all this circuit is more a gimmick than anything else and I didn't even start complaining about the way too high occurring voltage spikes that will destroy your MOSFETs sooner or later. So please do not connect such a circuit to a battery and do not believe in any of those simple BLDC driver videos because they all hide some information. But if you want a cheap and simple ESC then get this one from Aliexpress. With that being said I hope you enjoyed this video and if you are still wondering why the driver also works with 3 wire motors just a good/bad as with 4 wire ones, then let me tell you that I think that those two current paths are apparently enough. But this MOSFET right here will probably not like that for a long time. But anyway as always consider supporting me through Patreon to keep the show going. Don't forget to like, share, subscribe and hit the notification bell. Stay creative and I will see you next time.
