To be fair, Elon is planning to visit other planetsI think Tesla should start using the planetary gear system
The Models S Plaid has the reverse problem, in that they have to reduce power to the wheels on launch because the electric motors have too much torque, meaning the tyres will break traction up until fairly high speeds. Despite this low ratio gearing they still have to carbon wrap the rotors to stop it from flying apart at high RPM. A higher ratio, which is the primary benefit from a planetary gear would just make the problem worse, not better.John K, I get you.
The amount of cost is really limited to a minimum as is the difficulty and reliability problem. The amount of performance gained will be enormous. The torque delivered at a stand still can be increased by 4 times (not sure of the actual difference in starting torque vs full speed torque for Tesla) and the efficiency goes up as well, to near maximum. The increase in weight would be the weight of a planetary gear set, if two motors are already being used. Planetary gear sets are notoriously reliable and long lasting.
It may not be necessary for all situations. A families first car may not need it. Although, it is cheap enough to be a serious consideration.
If Tesla's reputation as a leader is going to hold out into the semi truck market, or even the light truck market, then they may need to adopt this technology. It is ideal for the induction motor. (If you ask me, it almost looks like the drive train was designed to have this planetary gear dropped right in, if you replaced the round inverter with another motor.)
The torque is easily reduced by reducing the magnitude of the d-q vector. It can be switched anywhere within its reachable range to anywhere else in that range (magnitude and phase) within milliseconds. The only gearing that is necessary is that necessary to get the most efficient design motor speed down to range of tyre speeds that typify cruise. There is no need to shift gears (though some designers do have a second gear). Tesla has done the trades and found this un-necessary while outperforming the vehicles that do shift gears.The Models S Plaid has the reverse problem, in that they have to reduce power to the wheels on launch because the electric motors have too much torque, meaning the tyres will break traction up until fairly high speeds. Despite this low ratio gearing they still have to carbon wrap the rotors to stop it from flying apart at high RPM. A higher ratio, which is the primary benefit from a planetary gear would just make the problem worse, not better.
My argument was that it is unnecessary for Tesla electric motors to use a "planetary gear" because there is a need to increase the deliverable torque to the wheels.The torque is easily reduced by reducing the magnitude of the d-q vector. It can be switched anywhere within its reachable range to anywhere else in that range (magnitude and phase) within milliseconds. The only gearing that is necessary is that necessary to get the most efficient design motor speed down to range of tyre speeds that typify cruise. There is no need to shift gears (though some designers do have a second gear). Tesla has done the trades and found this un-necessary while outperforming the vehicles that do shift gears.
Nope because planetary gear systems necessary to give the assortment of ratios that would be necessary to stay at the peak efficiency would required several stages as was done in the automatic transmissions of the days of yore with ICE vehicles where what you are thinking does apply because those engines have narrow torque and efficiency peaks. Electric motors have very broad ones.We can be more efficient than either the induction motor or the reluctance motor because we can choose what speed the motors are running at. We can run them near their most efficient speed most of the time. You don't get a choice.
ELectric motors can put out full torque at 0 rpm and they do it with nothing more than a garden variety reduction gear. This is how the 2500 kg Teslas are able to get to 60 mph in a few seconds.We can get a lot more torque at 0 rpm than the motor can put out at 0 rpm because the motors are running at full speed.
To "maximize the effect of the induced current in the rotor" the flux linkage component of the vector current is increased to whatever it needs to be. Torque is controlled through slip in an induction motor and through field angle relative to the rotor in PM motors..Say the field speed needs to run at 5 Hz when the shaft is at 0 rpm, in order to maximize the effect of the induced current in the rotor.
That's got nothing to do with it. The torque produced depends on the magnetizing current and the torque current, independently controllable, and either the slip or the angle depending on whether the motor is IM or PM.The linear distance that field can travel is fixed distance based on the radius of the rotor.
Again you reveal that you know little about AC machines (disclaimer: I don't know that much either - it is a very complicated subject) or about 3 ø systems. Power is not delivered in "pulses" (these are not DC brushless motors - they are 3 ø AC motors). It is delivered continuously.If the motor is able to get up to speed and the field can operate at say 400 Hz that is an additional 395 pulses of similar amounts of energy delivered per second. That is why this system is MUCH more powerful than a simple motor.
Un necessary in either which is why Tesla, who believe it or not know considerably more about these matters than you do, have not elected to use it.Perfect for the Semi (and my truck, I want it in my truck).
It is not necessary to use such a kluge for good regen braking as is demonstrated by the fact that the modern crop of Teslas already have it, with nothing more than simple (relatively) reduction gearing, to the point where one pedal driving to a full stop is available to the driver.[But wait, that's not all.] This system also allows you to get effective and efficient regeneration down to 0 rpm. You get all that for the price of a planetary gear set (and the additional weight of the aluminum case that will need to be beefed up to handle the torque).
Wasn't disagreeing. Just trying to amplify.My argument was that it is unnecessary for Tesla electric motors to use a "planetary gear" because there is a need to increase the deliverable torque to the wheels.
Any car does in the sense that the maximum torque is seldom required i.e. when coming out of the blocks or passing. At any other time the motor(s) can supply more torque than is necessary and so we turn the toque knob to a setting less than 11.My comparison was that the Model S Plaid actually has to reduce the torque (as you described) because it had too much torque...