5 ms·

Feel free to educate me... > The HET is a three-dimensional, circumferential flux, exterior > permanent magnet electric motor with some interesting > charact

by bArray 7y ago

Feel free to educate me... > The HET is a three-dimensional, circumferential flux, exterior > permanent magnet electric motor with some interesting > characteristics. For starters, it runs four rotors where other motors > typically run one or two. The stator is fully encapsulated in a four > sided "magnetic torque tunnel," each side having the same polarity, > ensuring that all magnetic fields are in the direction of motion, and > there are no unused ends on the copper coils wasting energy. All > magnetism the system creates is thus used to create motion, and all > four sides of the stator contribute torque to the output. I'm not so sure about the idea that "unused ends" are "wasting energy". Simply put your finger on a small spinning motor and watch the current go up - increase the work done, increase the power usage. Typical losses in magnetic motors are: 1. Friction - Bearings, brushes, etc 2. Air - Typically cooling 3. Core - Hysteresis (changing polarity is not possible instantly) and eddy current losses (unwanted current flow) 4. Resistance - The coils themselves resist high current Brushless motors are typically 85-90% efficient and brushed typically reach 75-80% efficiency [1]. Reducing the size a little, sure, but increasing the torque - I highly doubt for the same power input. I'm sure we will get to 95% efficiency within the next 10 years or so (with big money from the automotive industry pushing research), but it's highly unlikely we will get more than that outside of the a lab with super-cooled conductors. Which is the other thing, increasing the amount of torque and reducing the size means greater heat generation. Any saving in size you're getting gets lost again just keeping the motor cool. Anyway, the promises don't pass basic scrutiny, I would definitely need to see some numbers on this. It sounds like snake oil. EDIT: Another thing - electric motors are already very efficient, you're getting more loss in other parts, such as voltage regulators, motor control circuitry, batteries (if you're using them), cooling, etc, etc. I just don't think this will translate to a massive improvement. [1] http://dronenodes.com/drone-motors-brushless-guide/ http://dronenodes.com/drone-motors-brushless-guide/

codeflo 7y ago
I agree about the article, I just want to mention that improving motor efficiency would also help with some of the other losses you mention. Going from 80% to 90% means that you need half as much cooling, batteries may be more efficient when you draw less power from them, etc. That might it worth it even if the motor efficiency gain alone doesn’t look like much on paper.
- bArray 7y ago
  > Going from 80% to 90% means that you need half as much > cooling At the very most this will be < 5% performance increase because they'll need to match the best of BLDC (~90%) and 100% is simply impossible as there are losses that cannot be engineered out (thanks Physics). Also that 80% -> 90% isn't all heat, I imagine the amount of cooling required to stay roughly the same. > batteries may be more efficient when you draw less power > from them, etc. From memory, a switch mode power supply is one of the most efficient at about 90% - but you really have to design it well to get that kind of efficiency [1]. The batteries were a soft point for cars. But there's quite a bit of efficiency to get from phase control algorithms which would be in the motor control circuit. [1] https://en.wikipedia.org/wiki/Switched-mode_power_supply https://en.wikipedia.org/wiki/Switched-mode_power_supply
  - codeflo 7y ago
    What do you mean, it’s not all heat — of course it is, that’s kind of the definition of efficiency.
- hwillis 7y ago
  > I just want to mention that improving motor efficiency would also help with some of the other losses you mention. It's not that simple. Increases in torque are strongly associated with increases in current- torque is directly proportional to total magnetic flux, so more torque in a smaller package generally means more current in your wires. The alternative is to add more turns of thinner wire, but thinner wire has lower packing efficiency. Losses from current rise as RI^2 in simple wires, slightly faster in transistors, and some very complex factor in batteries that I can't remember but is between I^3 and I^4. You can make a 100% efficient motor, but if it quadruples the current draw then it will be almost useless for vehicles.
  - raxxorrax 7y ago
    But the missing torque necessitates a transmission as the article mentions that will also have a limited degree of efficiency.
tinco 7y ago
I'm a total novice to electric motor design, but they mention being able to switch between simulating phases. I don't think they mean they do higher torque at lower power input. I think it means that they can transparently trade efficiency for higher torque, so they can be efficient at low torque, high speed, while also be able to deliver torque at low speed without requiring gearing. I know how marketing departments work, if you have a product that has only one advantage over the competition, then they'll go and market your product as if it's the best at every point. I bet they've come up with this design that eliminates the need for gearing while retaining efficiency at low torque, and the rest is just marketing jabber.
- natermer 7y ago
  I'm a lay person somewhat familiar with the terminology. I am going to be wrong on several details. What they were talking about is phase weakening. Think of voltage as 'electrical pressure'. Like PSI or Bar. Think of amperage as 'volume per second' or 'amount of electrons (equivalent charge) per second'... like liters per minute. Combine the volume per second by pressure and you get total energy per second; watts. Hence 'voltage * amps = watts' Electric motors are also generators. When they spin they create their own 'reverse voltage', sometimes called 'Back EMF', that creates resistance in the windings of the motor. The faster the motor spins the greater this 'back emf'. It'll increase until the 'back emf' creates enough resistance that it effectively negates the voltage coming from the power source. At that point the motor has reached it's top speed. This is why DC motors don't try to spin infinitely fast. The strength of the motor, the torque, is directly related to the amount of amperage flowing. When the motor is at it's top speed it's generating only enough torque to overcome the resistance of the bearings and other parasitic drag. So very little actual current is flowing, especially in a very efficient motor. Field weakening is a technique that you can use to overcome some of this limitation. What it does is change the shape of the voltage wave. Most of the time on a oscilloscope it would show up as a sine wave or trapezoid... But if you can change the timing and peak of the wave then you can effectively weaken the magnetic field at the right time that the 'back emf' isn't as strong. Sort of flatten out the peak and make the pulse wider then it normally would be. So you end up flowing less peak amperage, but overall more amperage. Depending on the type of motor and speed the amount of extra torque/amperage you can generate can be very significant. The trade off is reduced efficiency. A simple motor surface mount magnet may only see a 20-30% increase in top speed and decrease in torque at the low end. A more modern interior mounted magnet (were magnets are embedded inside of steel laminates) that combines the strength of the rare earth magnets with reluctance of the magnetic field flowing through the steel.. (think of the magnets providing their own force at low end and then providing a guiding path for magnetic flux as the motor speeds up) Can see many multiples boost in top speed while still maintaining significant torque at low end. Field weakening on some motors can produce increased torque across the entire RPM range. This is going to be very strongly taken advantage of in EVs like the Tesla Model 3. Although in the case of most motors this field weakening is done electronically, by changing the shape of the waves sent to the motor. This design does the same thing, but by moving the drum's magnets out of phase with the magnets on either side. So it's mechanical field weakening. It's not a super-new concept or anything. I expect their patents have to do with the 'H' shape of the spindle and the math behind how it is supposed to work. I don't know if mechanical field weakening really provides any real benefit over electronically controlled one.
Freestyler_3 7y ago
I think the place where automotive and electric engines make the biggest leaps in the coming 20 years is in batteries. smaller and better batteries allows bigger and better motors.
- adrianN 7y ago
  Better batteries allow lighter cars which allow smaller motors. It's pretty ridiculous to move a three ton object in order to move a single human, if you think about it.

by bArray 7y ago

codeflo 7y ago

I agree about the article, I just want to mention that improving motor efficiency would also help with some of the other losses you mention. Going from 80% to 90% means that you need half as much cooling, batteries may be more efficient when you draw less power from them, etc. That might it worth it even if the motor efficiency gain alone doesn’t look like much on paper.

bArray 7y ago
> Going from 80% to 90% means that you need half as much > cooling At the very most this will be < 5% performance increase because they'll need to match the best of BLDC (~90%) and 100% is simply impossible as there are losses that cannot be engineered out (thanks Physics). Also that 80% -> 90% isn't all heat, I imagine the amount of cooling required to stay roughly the same. > batteries may be more efficient when you draw less power > from them, etc. From memory, a switch mode power supply is one of the most efficient at about 90% - but you really have to design it well to get that kind of efficiency [1]. The batteries were a soft point for cars. But there's quite a bit of efficiency to get from phase control algorithms which would be in the motor control circuit. [1] https://en.wikipedia.org/wiki/Switched-mode_power_supply https://en.wikipedia.org/wiki/Switched-mode_power_supply
- codeflo 7y ago
  What do you mean, it’s not all heat — of course it is, that’s kind of the definition of efficiency.
hwillis 7y ago
> I just want to mention that improving motor efficiency would also help with some of the other losses you mention. It's not that simple. Increases in torque are strongly associated with increases in current- torque is directly proportional to total magnetic flux, so more torque in a smaller package generally means more current in your wires. The alternative is to add more turns of thinner wire, but thinner wire has lower packing efficiency. Losses from current rise as RI^2 in simple wires, slightly faster in transistors, and some very complex factor in batteries that I can't remember but is between I^3 and I^4. You can make a 100% efficient motor, but if it quadruples the current draw then it will be almost useless for vehicles.
- raxxorrax 7y ago
  But the missing torque necessitates a transmission as the article mentions that will also have a limited degree of efficiency.

tinco 7y ago

I'm a total novice to electric motor design, but they mention being able to switch between simulating phases. I don't think they mean they do higher torque at lower power input. I think it means that they can transparently trade efficiency for higher torque, so they can be efficient at low torque, high speed, while also be able to deliver torque at low speed without requiring gearing. I know how marketing departments work, if you have a product that has only one advantage over the competition, then they'll go and market your product as if it's the best at every point. I bet they've come up with this design that eliminates the need for gearing while retaining efficiency at low torque, and the rest is just marketing jabber.

natermer 7y ago
I'm a lay person somewhat familiar with the terminology. I am going to be wrong on several details. What they were talking about is phase weakening. Think of voltage as 'electrical pressure'. Like PSI or Bar. Think of amperage as 'volume per second' or 'amount of electrons (equivalent charge) per second'... like liters per minute. Combine the volume per second by pressure and you get total energy per second; watts. Hence 'voltage * amps = watts' Electric motors are also generators. When they spin they create their own 'reverse voltage', sometimes called 'Back EMF', that creates resistance in the windings of the motor. The faster the motor spins the greater this 'back emf'. It'll increase until the 'back emf' creates enough resistance that it effectively negates the voltage coming from the power source. At that point the motor has reached it's top speed. This is why DC motors don't try to spin infinitely fast. The strength of the motor, the torque, is directly related to the amount of amperage flowing. When the motor is at it's top speed it's generating only enough torque to overcome the resistance of the bearings and other parasitic drag. So very little actual current is flowing, especially in a very efficient motor. Field weakening is a technique that you can use to overcome some of this limitation. What it does is change the shape of the voltage wave. Most of the time on a oscilloscope it would show up as a sine wave or trapezoid... But if you can change the timing and peak of the wave then you can effectively weaken the magnetic field at the right time that the 'back emf' isn't as strong. Sort of flatten out the peak and make the pulse wider then it normally would be. So you end up flowing less peak amperage, but overall more amperage. Depending on the type of motor and speed the amount of extra torque/amperage you can generate can be very significant. The trade off is reduced efficiency. A simple motor surface mount magnet may only see a 20-30% increase in top speed and decrease in torque at the low end. A more modern interior mounted magnet (were magnets are embedded inside of steel laminates) that combines the strength of the rare earth magnets with reluctance of the magnetic field flowing through the steel.. (think of the magnets providing their own force at low end and then providing a guiding path for magnetic flux as the motor speeds up) Can see many multiples boost in top speed while still maintaining significant torque at low end. Field weakening on some motors can produce increased torque across the entire RPM range. This is going to be very strongly taken advantage of in EVs like the Tesla Model 3. Although in the case of most motors this field weakening is done electronically, by changing the shape of the waves sent to the motor. This design does the same thing, but by moving the drum's magnets out of phase with the magnets on either side. So it's mechanical field weakening. It's not a super-new concept or anything. I expect their patents have to do with the 'H' shape of the spindle and the math behind how it is supposed to work. I don't know if mechanical field weakening really provides any real benefit over electronically controlled one.

Freestyler_3 7y ago

I think the place where automotive and electric engines make the biggest leaps in the coming 20 years is in batteries. smaller and better batteries allows bigger and better motors.

adrianN 7y ago
Better batteries allow lighter cars which allow smaller motors. It's pretty ridiculous to move a three ton object in order to move a single human, if you think about it.