Toyota development staff explained, “When the second generation from the Prius becomes the third generation,” the width of the motor / generator has halved “.
Toyota’s hybrid system including the Prius is equipped with two motors / generators. If it mainly works as a motor and brings about regeneration during deceleration, it is expressed as a motor to show its function.
On the other hand, since the motor generator used for power generation during running and engine startup mainly functions as a generator, when describing its function, it is expressed as a generator.
Motors / generators, which mainly operate as engines as power generators, make different ways to become the 3rd generation Prius. It is the way of winding the copper wire of the internal geothermal stone.
The two motors / generators used in Toyota’s hybrid system, including the Prius, are synchronous systems that use permanent magnets.
This is a powerful permanent magnet using rare-earth neodymium for the rotation axis is used. In addition, an electromagnet is used on the case side of the motor.
There are two ways of winding when wrapping a copper wire around the iron core of the electromagnet, “distributed winding” and “concentrated winding”, two generators from the first Prius and two generators of the motor / generator Although it was volumes, from the third generation, it is said that the generator was concentrated.
By changing this winding method, we succeeded in miniaturization.
So, what is the difference between distributed winding and concentrated winding?
In distributed winding, electromagnets are arranged inside the motor case, and copper wires are wound around the iron core.
Where copper wire is led to the adjacent iron core, the copper wire overlaps.
Since the copper wires overlap, the width of the whole motor becomes thicker.
– As for the concentrated winding, wind copper wire for each iron core of each electromagnet. It does not share copper wire with other electromagnets, so the windings of the copper wires do not overlap.
Therefore, the width of the motor can be finished thin.
For example, in the case of winding a hose used for watering etc …
When winding a long hose onto a reel, if you roll it neatly so that there is no gap, it fits well in the winder. However, if you roll around easily, the hose is wound obliquely, and the hoses overlap each other, so the rolled hose gets thicker overall, making it difficult to fit in the winder.
Likewise, if there is a part wrapped obliquely to lead the copper wire to the next core, the overlapping causes the motor / generator to become thick.
Reduce motor / generator width in concentrated winding
So why have you so far adopted distributed windings? That has a good reason.
A distributed winding motor / generator is excellent in output and smoothness.
When an electric current flows in the electromagnet and a magnetic force is generated in the electromagnet, the axis of the permanent magnet rotates. When the driver depresses the accelerator pedal, the electric power flowing to the electromagnet increases and the turning power of the motor also increases. At this time, in the distributed winding, the electromagnets of each other are connected by a copper wire and are related, so the intensity does not show strength and it can be accelerated smoothly.
– On the other hand, concern when adopting concentrated winding is a problem for the smoothness of acceleration.
Coil wires are wound around each electromagnet in concentrated winding, and the copper wire has no relation with another electromagnetic. Therefore, the strength of the motor’s rotational force called “torque fluctuation” is easily vulnerable. The reason for this is because of a gap between the electromagnet and the electromagnet where the force is interrupted.
It causes a jerky speed change during acceleration. Toyota hated that. However, if it is used as a generator, the fluctuation due to its strength is not directly related to the acceleration of the car. Therefore, we adopted concentrated winding for the motor / danger used as a generator, and reduced the width to about half.
If the width is reduced to nearly half, the amount of copper wire used will be reduced. Cost will be reduced if parts materials are reduced. Miniaturization of the motor is directly related to price reduction.