mtbenjamin77
06-18-2012, 02:25 PM
After some interent research I found some info that some might find helpful.........
http://www.aveox.com/Faq.aspx
A. Eliminating the brushes and commutator buys you a lot. First, since there is no brush drag, the overall efficiency of the motor is higher. Second, there is far less electrical noise generated to interfere with the remote control. Thirdly, there is no required maintenance on the brushless motor and there is no deterioration of performance over the life of the motor.
Another major advantage of brushless motors is they run efficiently over a much wider range of power. For instance, our 1412/2 can easily be used as both a seven cell direct motor and a 27 cell F5B motor. The reason is two fold. In a brushed motor used at lower power levels, the iron or (input volts times the no load current) losses, and brush drag tend to be the dominate loss in the motor. Since this is much lower in a brushless motor, they are efficient at light loads. At higher powers, the copper or (input current squared times motors resistance) losses tend to dominate. Since brushless motors usually have lower resistance in the windings, they are more efficient at higher loads.
Because there is no mechanical component in the commutation of a brushless motor, they can reliably operate at higher rpm's. A '40' sized brush motor typically is not recommended to operate faster than 16,000- 20,000 rpm. Since the equivalent sized brushless motor can operate at two to three times that rpm, you can use a smaller brushless motor with a gearbox to get the same torque as a larger brushed motor.
It is interesting to note that at this year’s F5B world championship, 40 out of some 50 competitors were using a brushless motor system. All winning entries used brushless motors. For sport fliers, brushless motors offer a reliable system with less maintenance headaches. Brushless motors can grow with you since you can easily use the same motor in a 7 cell airplane and later in a 20 cell airplane. Right now, for very small 1/2A airplanes, the best choice is a probably a Speed 400 brush motor, because there are no commercially available small brushless motors comparable to an .049 gas motor, but we believe this will change soon. BACK
Q. Do I need to use a brushless controller, or can I use my speed controller from my other motors?
A. Since brushless motors are essentially 3-phase AC motors that are commutated electronically, a brushed motor speed controller cannot be used. Each brushless motor has 3 power wires instead of the 2 found in a brushed motor, along with five sensor wires, that allow the motor to tell the controller where it is. These sensor wires take the place of the commutator in a brushed motor, and do the same job. The advantage to a brushless controller is that there must be a minimum of 6 mosfets (Aveox controllers use 12) to commutate the motor. This makes the effective ON resistance lower than a typical brushed contoller and therefore it will stay cooler at high power levels. BACK
Q. With so many motors, How do I decide which is the best one for me?
A. With all the different motors offered by Aveox, selecting one just right for your model can be challenging. The first thing you need to determine is what the normal operating current is for your particular application. If you have a sailplane that needs very high power for, fast, but very short climbs, you would want to run in the 50-80 amp range. These applications call for 'HOT' wind motors like the F series, or 2Y motors. If you want to fly a large old-timer forever, you might want to operate as low as 3-5 amps. These work best with geared higher turn motors like the 4Y or 5Y series. The typical “sport plane”, that operates in the 10-35 amp range, works well with the 3 turn models.
Based on the weight "Rules of Thumb" 50 -100 input watts per pound, where 50 watts is comfortable, and 100 is awesome, calculate the current needed. For example, if you think that your airplane needs 200 watts of input power to fly, and you run on 10 cells, you would need a motor whose best operating point is at 20 amps. Check the motor specification chart on the motor page, and you will see that the /3Y motors operate best at this current.
You should also design the system for the correct motor. If you like to fly Kadet Seniors at 200 watts, you do not want to use a system that is designed for 1000 watts throttled back to 200. You will be much better off with a system that puts out a max power of 250 watts, and throttle back from that. Remember, all controllers, including brushed controllers, like to be as close to full throttle as possible, and suffer the most abuse at about 20% throttle.
Then, check the motor selection chart for motor recommendations. When all else fails, call us for advice!.BACK
Q. What are the advantages of gearing?
A. Each motor work very well as a geared system. The only planes that typically don't benefit from gearing are very high-speed planes. Typically, the overall system is lighter, and more efficient. The 1406/4Y, 3.7:1 planetary gearbox, and APC 12x8 prop draws 19A on 21 cells. The combination spins the prop approximately 8500 rpm, and produces about 75 ounces of static thrust. This is an excellent combination for the "pattern" type of aircraft. Unfortunately, the landing gear of many planes will not allow a prop over 12” to be installed. Call for geared applications. If you choose a European imported gearbox, such as the Kruse line, our motors are available with metric front end bells on request (M3 holes on 25mm centers). We build metric motors to order, at no additional charge. BACK
Q. In a brushless motor system, what's the difference between a Delta wind and a Wye wind? What are the advantages and disadvantages?
A. Get a pencil and paper for this. <There's not a nice way to do this with ASCII art>
"Wye" wind Motor
Draw 3 resistors (or coils) radiating from a central point (The Wye tie). Label the three ends A, B, and C. These represent the three phase connections in the Wye motor.
In the controller, each of these has 2 pair of MOSFETs connected to it, a pair to source the current, and a pair to sink the current. The motor fires like this (simplified for clarity) A-B, A-C, B-C, B-A, C-B, C-A ad nauseam. The Magnets "chase" the rotating magnetic field. Notice that there are always 2 phases "commutated" at the same time, but the mix differs, and the current direction will reverse every other time. The motors resistance is the sum of any two phases i.e. measure from any 2 phases. The third phase is open electrically when any other 2 are commutated.
"Delta" wind Motor
Draw 3 resistors connected in a triangle (delta). Each of the vertices is a phase. When you commutate CA-AB, you get most of the energy on one coil, (A), but some on (A-C-B) side. (mostly imo losses). The net result of most of the current going through one set of coils at a time, instead of two is that the Kt <torque constant (tm)> is cut in half and Kv <motor constant, RPM/volt (tm)> doubles.
At Aveox, we have essentially deemed the Deltas as secondary to Wye winds in any application, except where a very high degree of uniformity in both directions is very important. Things like robots that move in both directions equally put up with the efficiency losses. Since the motors are very insensitive to timing changes (unlike the Wye winds), you don't have great performance in one direction, and poor in another(without adjusting the timing). You have good performance in both. (but it is not worth the losses in a model)
They have been discontinued at Aveox for a couple of years. We do what we can to get them out of circulation by changing them over at a loss. (However, they are really easy to make if you insist). When you finish winding a stator, you have 6 wires coming out, the start and finish of each phase. Connect every other one together to make the Wye tie, or adjacent pairs to make the Delta. BACK
http://www.aveox.com/Faq.aspx
A. Eliminating the brushes and commutator buys you a lot. First, since there is no brush drag, the overall efficiency of the motor is higher. Second, there is far less electrical noise generated to interfere with the remote control. Thirdly, there is no required maintenance on the brushless motor and there is no deterioration of performance over the life of the motor.
Another major advantage of brushless motors is they run efficiently over a much wider range of power. For instance, our 1412/2 can easily be used as both a seven cell direct motor and a 27 cell F5B motor. The reason is two fold. In a brushed motor used at lower power levels, the iron or (input volts times the no load current) losses, and brush drag tend to be the dominate loss in the motor. Since this is much lower in a brushless motor, they are efficient at light loads. At higher powers, the copper or (input current squared times motors resistance) losses tend to dominate. Since brushless motors usually have lower resistance in the windings, they are more efficient at higher loads.
Because there is no mechanical component in the commutation of a brushless motor, they can reliably operate at higher rpm's. A '40' sized brush motor typically is not recommended to operate faster than 16,000- 20,000 rpm. Since the equivalent sized brushless motor can operate at two to three times that rpm, you can use a smaller brushless motor with a gearbox to get the same torque as a larger brushed motor.
It is interesting to note that at this year’s F5B world championship, 40 out of some 50 competitors were using a brushless motor system. All winning entries used brushless motors. For sport fliers, brushless motors offer a reliable system with less maintenance headaches. Brushless motors can grow with you since you can easily use the same motor in a 7 cell airplane and later in a 20 cell airplane. Right now, for very small 1/2A airplanes, the best choice is a probably a Speed 400 brush motor, because there are no commercially available small brushless motors comparable to an .049 gas motor, but we believe this will change soon. BACK
Q. Do I need to use a brushless controller, or can I use my speed controller from my other motors?
A. Since brushless motors are essentially 3-phase AC motors that are commutated electronically, a brushed motor speed controller cannot be used. Each brushless motor has 3 power wires instead of the 2 found in a brushed motor, along with five sensor wires, that allow the motor to tell the controller where it is. These sensor wires take the place of the commutator in a brushed motor, and do the same job. The advantage to a brushless controller is that there must be a minimum of 6 mosfets (Aveox controllers use 12) to commutate the motor. This makes the effective ON resistance lower than a typical brushed contoller and therefore it will stay cooler at high power levels. BACK
Q. With so many motors, How do I decide which is the best one for me?
A. With all the different motors offered by Aveox, selecting one just right for your model can be challenging. The first thing you need to determine is what the normal operating current is for your particular application. If you have a sailplane that needs very high power for, fast, but very short climbs, you would want to run in the 50-80 amp range. These applications call for 'HOT' wind motors like the F series, or 2Y motors. If you want to fly a large old-timer forever, you might want to operate as low as 3-5 amps. These work best with geared higher turn motors like the 4Y or 5Y series. The typical “sport plane”, that operates in the 10-35 amp range, works well with the 3 turn models.
Based on the weight "Rules of Thumb" 50 -100 input watts per pound, where 50 watts is comfortable, and 100 is awesome, calculate the current needed. For example, if you think that your airplane needs 200 watts of input power to fly, and you run on 10 cells, you would need a motor whose best operating point is at 20 amps. Check the motor specification chart on the motor page, and you will see that the /3Y motors operate best at this current.
You should also design the system for the correct motor. If you like to fly Kadet Seniors at 200 watts, you do not want to use a system that is designed for 1000 watts throttled back to 200. You will be much better off with a system that puts out a max power of 250 watts, and throttle back from that. Remember, all controllers, including brushed controllers, like to be as close to full throttle as possible, and suffer the most abuse at about 20% throttle.
Then, check the motor selection chart for motor recommendations. When all else fails, call us for advice!.BACK
Q. What are the advantages of gearing?
A. Each motor work very well as a geared system. The only planes that typically don't benefit from gearing are very high-speed planes. Typically, the overall system is lighter, and more efficient. The 1406/4Y, 3.7:1 planetary gearbox, and APC 12x8 prop draws 19A on 21 cells. The combination spins the prop approximately 8500 rpm, and produces about 75 ounces of static thrust. This is an excellent combination for the "pattern" type of aircraft. Unfortunately, the landing gear of many planes will not allow a prop over 12” to be installed. Call for geared applications. If you choose a European imported gearbox, such as the Kruse line, our motors are available with metric front end bells on request (M3 holes on 25mm centers). We build metric motors to order, at no additional charge. BACK
Q. In a brushless motor system, what's the difference between a Delta wind and a Wye wind? What are the advantages and disadvantages?
A. Get a pencil and paper for this. <There's not a nice way to do this with ASCII art>
"Wye" wind Motor
Draw 3 resistors (or coils) radiating from a central point (The Wye tie). Label the three ends A, B, and C. These represent the three phase connections in the Wye motor.
In the controller, each of these has 2 pair of MOSFETs connected to it, a pair to source the current, and a pair to sink the current. The motor fires like this (simplified for clarity) A-B, A-C, B-C, B-A, C-B, C-A ad nauseam. The Magnets "chase" the rotating magnetic field. Notice that there are always 2 phases "commutated" at the same time, but the mix differs, and the current direction will reverse every other time. The motors resistance is the sum of any two phases i.e. measure from any 2 phases. The third phase is open electrically when any other 2 are commutated.
"Delta" wind Motor
Draw 3 resistors connected in a triangle (delta). Each of the vertices is a phase. When you commutate CA-AB, you get most of the energy on one coil, (A), but some on (A-C-B) side. (mostly imo losses). The net result of most of the current going through one set of coils at a time, instead of two is that the Kt <torque constant (tm)> is cut in half and Kv <motor constant, RPM/volt (tm)> doubles.
At Aveox, we have essentially deemed the Deltas as secondary to Wye winds in any application, except where a very high degree of uniformity in both directions is very important. Things like robots that move in both directions equally put up with the efficiency losses. Since the motors are very insensitive to timing changes (unlike the Wye winds), you don't have great performance in one direction, and poor in another(without adjusting the timing). You have good performance in both. (but it is not worth the losses in a model)
They have been discontinued at Aveox for a couple of years. We do what we can to get them out of circulation by changing them over at a loss. (However, they are really easy to make if you insist). When you finish winding a stator, you have 6 wires coming out, the start and finish of each phase. Connect every other one together to make the Wye tie, or adjacent pairs to make the Delta. BACK