Tesla Model 3's motor - The Brilliant Engineering behind it

Tesla Motors engineers made a surprising design decision when developing the Tesla Model 3: they abandoned the proven and conventionally used induction

motor

s and replaced them with a new type of

motor

, the ipm syn rm. These engines have a totally different design that uses both. magnetic and reluctance action the great news is that

tesla

motors has started replacing the induction motors in their

model

s with these new motors and also how these motors work. What is special about ipm cinerm? Let's explore to get a clear answer. First we must clearly understand the electric motor of

model

s, which is an induction motor, as you can see, the rotating part here is a conductive rod arrangement.

Alternating currents from the battery packs flow into the external windings of the motor, which will create a rotating magnetic field with which the fluctuating field interacts. the rotor bars and generates electromotive forces on them, which in turn generates currents in the rotor bars, the interaction between these induced currents and the rmf imposes force on the rotor bars and the rotor begins to rotate. These motors are efficient but are not up to par. For example, long trips at cruising speed lose three to four percent of energy to generate currents in the rotor bars, which is definitely not efficient.

Furthermore, for a car, the most important performance parameter is its starting torque, although induction motors have better starting torque than induction motors. IC motors there is a motor technology that provides even better starting torque with the same motor volume. Motor technology based on permanent magnets. PM motors work based on the attraction between two magnetic fields. They produce good starting torque when operated using a controller and experience no rotor power loss. An efficient permanent magnet rotor can be made by placing permanent magnets around a solid iron cylinder, so why not replace the squirrel cage type rotor with a permanent magnet?

These four permanent magnets produce a combination. magnetic field the shape of this combined field is quite important for further analysis with a little intuition the combined magnetic field of these four magnets can be plotted as shown now we need to analyze the interaction between the rmf and the combined magnetic field by analyzing the force interaction between two magnetic fields is simple, just look at how the south and north poles interact with each other for simplicity, let's hide the magnetic field produced by the permanent magnets and keep only the north and south poles. The force interactions between the different poles are shown here at this angle. the rmf definitely produces a torque on the rotor now let's turn the rmf to 45 degrees, curiously at this angle the rotor experiences a maximum torque because the forces of attraction and repulsion pass almost tangential to the rotor and produce the torques in the same direction using With this Simple ball analogy, the reason behind why tangential forces produce maximum torque is clear, therefore this is the perfect angle to start your electric car.

Maintaining this angle or further regulation of the angle is the job of the smart controller in this design, the rotor has no induced current which reduces the input power required and leads to higher efficiencies than those of induction motors along with higher starting torque. The pm motor also operates at synchronous speeds, but the search for the perfect electric motor is not over yet. A permanent magnet motor produces good torque when starting the car. or going up a hill, however, when the car is driving on the road at high speeds, the permanent magnet motors have terrible performance, the villain here is the rear electromagnetic force, the magnetic field lines produced by the permanent magnets are linked with the stator windings and generate an electromagnetic force there, this electromagnetic force is called back emf, which is clearly an inverse voltage to the stator supply voltage, the higher the speed of the rotor, the more it produces back emf.

This phenomenon is why permanent motors perform terribly in high speed applications, plus these high strength magnets also result in magnetic eddy currents. Losses that increase heat in the machine, let's see how we can modify this design so that it works efficiently even at high speeds for high speed operations. Tesla engineers made use of the reluctance property of iron. The ability of a medium to oppose magnetic fields is known as reluctance. The iron nail sticks to a permanent magnet due to the force of reluctance. Iron is a good guardian of magnetic field lines, but air is not an interesting phenomenon.

It can be observed when grooves are cut in the iron in this position of the rotor. The rotor is in a state of high reluctance. However, if the rotor is rotated 45 degrees, it will face very low reluctance; The rotor always has a tendency to reach a low reluctance state, therefore, if the magnetic field rotates, the rotor will rotate along with it, so that the rotor can always be in a low reluctance state position. rotor will be the same as the rmf speed the torque produced by this phenomenon is known as reluctance torque and such motors are called synchronous reluctance motors.

Synchronous rms are highly efficient and, in short, have no back-emf problems. Permanent magnet motors are good at low speeds and synchronizers are quite good for high speed operations if we can integrate the synchronized technology into the permanent magnet motor we saw earlier, such a motor could work efficiently at any speed , a motor that uses both reluctance and permanent magnet. effects, we can easily achieve this design integration by placing the permanent magnets in the slotted cuts of the synchronized motor deep within the iron core. This location further reduces the effect of the magnet on the stator winding and therefore reduces the back emf.

This design is the internal permanent magnet synchronous reluctance. Tesla model 3 motor or motor, the relative permeability of the magnets is almost the same as that of air, so they will oppose the field to pass through it just as the air did before, thus generating the reluctance torque to analyze this engine correctly. It is necessary to observe the resulting magnetic field produced by the arrangement of permanent magnets. Fea em works 2d software paired along Solidworks comes to the rescue. The resulting magnetic field produced by this arrangement will be as shown. If these magnets were placed far apart, each magnet would create its own magnetic field as shown in the image on the left using this resulting field let's do a more detailed analysis the interesting thing about this design is that the permanent magnet and the reluctance parts of This motor have a totally different behavior with respect to the rmf position, let's analyze them Separately from our latest ipm cinerm design, remove the iron core and keep only the permanent magnets in this rmf position.

Permanent magnets will not experience torque since there is no tangential component to these four forces and the torque produced by the remaining forces cancels each other if the rmf is rotated 45 degrees a torque acts on the magnets in a clockwise direction Due to the effect of the rmf at this angle we obtain the maximum torque of the permanent magnets, let's see what happens when we turn it another 45 degrees, the torque the rotor produces returns to zero, allowing us to obtain the torque curve of the permanent magnet. The iron part of the rotor has a opposite effect in the same technique let's analyze it at the initial angle the torque production will be zero because it is a perfectly misaligned and symmetrical case when we slightly shift the rmf clockwise the rotor will experience a maximum and negative torque as it the rmf reaches 45 degrees the torque becomes zero again as this is a perfectly symmetrical case again as we turn the rmf further the reluctance torque produced will be positive now lets look at the

tesla

model 3 motor or the combined effect permanent magnetic and reluctance in the motor, it is clear from the total torque graph that if the rmf angle is around 50 degrees we will get the maximum torque of the motor, so tesla motor engineers make sure that when the motor starts car, the rmf angle is around 50 degrees, which will ensure maximum torque production.

We know that as the motor speed increases, the permanent magnets induce a back emf in the stator coils to overcome this problem. Tesla motors designed a solution that is quite simple to spin at high speeds, they align the rmf opposite the permanent magnetic field, as you can see the rmf weakens or almost cancels the permanent magnetic field in this way, even at high speeds, such motors they will not produce much back emf, obviously at this stage, the torque production will mainly come from the reluctance effect. The Model 3 uses a 6-pole design which is no different than the 4-pole design other than getting higher torque.

Tesla motors are not the first company to launch such an innovative motor. The Toyota Prius. A hybrid electric car uses similar IPM Synarm motor technology, it uses two IPM Cinerm machines, one to power the car and another to generate electricity. An interesting difference between the model 3 and Prius motor designs is in the magnets. Prius motors use solid magnets, while each magnet in the Model 3 motors is segmented into four parts. This segmentation reduces eddy currents in the magnets by preventing them from overheating, which in turn saves them from demagnetization and causes the motor to cool down. The 2019 version of the model cars has ipm syn rm installed at the front.

The ipm synrm motor has efficiencies of up to 96 percent compared to traditional induction motors of up to 94 percent efficiency. Effectively cooling the rotor of an induction motor is a major challenge. This problem is not present for ipm synrms with the added advantage of reluctance, these motors have higher torque values ​​than induction motors ipm synrms have definitely set new standards in the world of electric vehicles. We hope you enjoyed this explanation of how smart design decisions gave rise to a promising electric motor. Don't forget to be one of our followers, thank you.