The Ryobi motors are certainly designed for one specific application. So it may not even work to reverse the sensors sequence.

The motor is identical whether uni-directional or bi-directional, no reversing of sensors is needed.
It is dependent on the drive itself, and whether capable of reverse switching of the motor stator, exactly as it is in a commutated P.M. DC motor armature..

 

I’ve noticed that the Ryobi motor is capable of running very slowly. The ego in contrasts minimum speed is kinda fast. Perhaps the Ryobi is heavily sensored and this is where the difficulty lies?

 

. Perhaps the Ryobi is heavily sensored and this is where the difficulty lies?

The BLDC motor only requires three commutating sensors, one for each stator phase. which can be from 2 pole up to usually max of 8.

 

@MaxHeadRoom , forgive me if I’m being dense as this is a mix of semi complex, and my eagerness to accomplish. If I were willing to use a multimeter and or whatever else to make measurements, is this still more complex than realigning the hall sensor wires with the phase wires in the exact opposite configuration? I’ve been digging around the Google trying to understand the fundamental workings of a hall sensored bldc motors and if there’s electrical timing involved, it seems reasonable that an accurate reversal of the wiring sequence would result in a similarly timed opposite motion. Looks like three phase wires and five sensor wires pos, neg, and three sensor leads?

The reason I persist with tackling the Ryobi in particular is not only am I heavily invested in batteries, tools and in vehicle charging infrastructure, it seems very few other brands have the precise speed control I desire. To add to the situation, any other brands with such electronics involved will land me right back in this exact position of dealing with hall sensors.

 

Consider the motor as a separate entity. The normal construction/design is the same for whether the end use is uni-directional or bi-directional.
Once the commutation sensors or means of sensing is properly aligned, it should stay that way.
The BLDC drive provides switching power to any two of the three windings based on the sensor feedback,
If bi-directional control is required, The drive itself has to be designed specifically for it .

 

Consider the motor as a separate entity. The normal construction/design is the same for whether the end use is uni-directional or bi-directional.
Once the commutation sensors or means of sensing is properly aligned, it should stay that way.
The BLDC drive provides switching power to any two of the three windings based on the sensor feedback,
If bi-directional control is required, The drive itself has to be designed specifically for it .

Am I understanding correctly that it can be reversed but by realigned wires with the correct sequence but then it’s only good for reverse? Again I apologize for my lack of understanding electronics on your level like this but if a motor alone is bidirectional then properly reversed sensor and phase wires will preserve the timing and feedback? Or do I need to let sleeping dogs lye here?

 

If it can’t be done then I’ll accept that as the final verdict.

 

You cannot

Am I understanding correctly that it can be reversed but by realigned wires with the correct sequence but then it’s only good for reverse?

It all depends if the motor controller itself is designed to allow bi-directional motor control.

 

Too bad, thanks for the information everyone, I appreciate all the input.

 

Alright, today I reversed the direction of my Ego powerhead with the switch of two phase wires and it’s wonderful having a straight shaft trimmer that spins in accordance with my chi. I’ve read something about additional load when doing something like this but I’m not sure if it only applies to sensored motors. Should I have any concerns about this and might I need to measure current or be aware of anything?

 

This is why I was trying so hard to make my Ryobi reverse. It’s just a more powerful string trimmer and even though I only really do maintained accounts more power is more power.

 

This is why I was trying so hard to make my Ryobi reverse. It’s just a more powerful string trimmer and even though I only really do maintained accounts more power is more power.

Do you use the whacker for the entire property with growth that big? And what runtime do you get from a full charge?

 

Alright, today I reversed the direction of my Ego powerhead with the switch of two phase wires and it’s wonderful having a straight shaft trimmer that spins in accordance with my chi. I’ve read something about additional load when doing something like this but I’m not sure if it only applies to sensored motors. Should I have any concerns about this and might I need to measure current or be aware of anything?

View attachment 267154

If it's a BLDC that uses a position (optical) encoder the two wire swap should work if your esc calculates (using FOC) the driver phase angles to keep in drive power sync with the encoder or uses open-loop sinusoidal commutation (unlikely). With hall encoding it's looking for a repeating pattern of magnetic sensor switching to move from pole(s) to pole.

In software I simply flip the PWM driver signals to reverse.

    if (V.forward) {
        MCPWM_ChannelPrimaryDutySet(MCPWM_CH_2, m35_2.duty);
        MCPWM_ChannelPrimaryDutySet(MCPWM_CH_3, m35_3.duty);
    } else {
        MCPWM_ChannelPrimaryDutySet(MCPWM_CH_3, m35_2.duty);
        MCPWM_ChannelPrimaryDutySet(MCPWM_CH_2, m35_3.duty);
    }

 

Do you use the whacker for the entire property with growth that big? And what runtime do you get from a full charge?

That was an abandoned lot I found driving around to do the comparison. I service nice yards that don’t need anywhere near what I’m asking of them in the video. I’ve stopped paying attention two years ago when I installed a pure sine wave inverter in my car running rapid tool chargers. In a yard like that I’d say the Ryobi would go 15 minutes with the 4ah batteries I prefer to use in it. The ego is way too new with me to even guess.

 

I’m gonna keep this thread on life support if y’all don’t mind. I found out that I underestimated the wattage potential of the Ego string trimmer, it’s apparently 1.2kw and possibly a little higher. I have a new dpdt switch that’s rated at 16A@ 125V AC, 10A@ 250V AC so unless I’m completely lost I believe it should offer plenty of headroom in the circuit. Headroom is the only term I have to convey the ability to pass more current then is needed.

My concern however is on resistance added into the circuit by extra connectors and the switch. Will gold plated spade terminals be fine? What about gold bullets? Something else? I’d like this to remain disconnect able just incase I need to make a change. Will a conductive lubricant or something similar aid in reducing resistance or am I going overboard here? The switch I have on the trimmer currently is rated at 20a @12v I feel this is creating a major bottleneck for the 1kw+ system.

 

I wanted to update anyone interested in this project. I just couldn’t take no for an answer without at least trying. I bought a bare powerhead unit for a hundred bucks to experiment with, without risking breaking the one I use for work. I continued reading and watching videos which educated me to test the hall sensor wires for the 5v leads narrowing down to only the corresponding sensor wires.

After a little process of elimination I was able to achieve a reversal of the motor with what appears to be a completely normal function, just rotating the other way. The next step is waiting for the 12 pin switch so I can switch the two hall and two phase wires with a single switch rated over 2,000w.

I’d love hear any concerns, measurements I might want to take to confirm that I did this correctly, or any other input someone might feel helpful. I appreciate all the input thus far

 

I have set up the timing commutation of many BLDC motors that happened to use encoder tracks rather than Hall sensors, but the end result is the same.
Ones setup and tuned the connections are Never touched or Reversed!
If they were to, the motor would not run.

 

I have set up the timing commutation of many BLDC motors that happened to use encoder tracks rather than Hall sensors, but the end result is the same.
Ones setup and tuned the connections are Never touched or Reversed!
If they were to, the motor would not run.

I don’t follow, my achieving a reversal means what? It’s not timed? Maybe the esc is from an R/C car? I’m fairly confident that the Ego trimmer motor is a repurposed R/C motor and control.

 

I am not totally sure what you have there, but I am referring to a typical BLDC motor and the commutation.

Here it is in detail via video.
https://lucidar.me/en/actuators/commutation-for-bldc-motors/

 

I wanted to update anyone interested in this project. I just couldn’t take no for an answer without at least trying. I bought a bare powerhead unit for a hundred bucks to experiment with, without risking breaking the one I use for work. I continued reading and watching videos which educated me to test the hall sensor wires for the 5v leads narrowing down to only the corresponding sensor wires.

After a little process of elimination I was able to achieve a reversal of the motor with what appears to be a completely normal function, just rotating the other way. The next step is waiting for the 12 pin switch so I can switch the two hall and two phase wires with a single switch rated over 2,000w.

I’d love hear any concerns, measurements I might want to take to confirm that I did this correctly, or any other input someone might feel helpful. I appreciate all the input thus far

If the motor runs and the controller doesn't fry, all is good. The hall sensor to motor phase table is simple.


The physics of motor motion by attraction or responsible is a vector. If you invert the vector matrix by software or hardware timing/sequencing of position sensors, the motor runs just fine if it freely spins in both directions.