What kind of machine is an automobile drive motor? [Basic technology of electric vehicles]
01. The principle by which the motor starts rotating and the principle by which it continues to rotate
An electric motor is a machine that converts electrical energy into physical energy called driving force, but it uses the magnetic field that surrounds it when electricity flows. However, this magnetic field is nothing more than a "field".
It is widely known that motors utilize the attraction and repulsion forces generated between magnets and the force that attracts iron, so-called magnetic force, but what is the magnetic field (also called the magnetic field) mentioned above? It is a field filled with this magnetic force, and it is a space that expands three-dimensionally.
When a magnet attracts a magnet or an object made of iron, such as a nail, the object (in this case, the magnet or nail that is attracted to the magnet) moves, or moves, while it is being attracted, but when the two touch, it stops moving. stops. Similarly, in the case of repulsive force between magnets, the motion ends when the two move apart to the point where the magnetic force reaches its limit of action. In contrast, the driving force we expect from motors is continuous, so to speak, never-ending motion. At the very least, a motor cannot be created if the parts just "click" together. In other words, just having a magnetic field is not enough.
Therefore, the motor constantly moves the magnetic field in order to obtain continuous power. More specifically, it is rotating. Think of it as creating a situation similar to the classic joke of dangling a carrot in front of a horse with a pole held by a jockey on the horse's back. No matter how much you run, a horse can't find a carrot forever.The rotor rotates as if chasing a rotating magnetic field, but when the rotor rotates, the magnetic field also rotates...This "illegal" composition is what makes a motor. This is the principle of operation. This rotating magnetic field is called a "rotating magnetic field," and it can be easily created with alternating current electricity, but only direct current can be obtained from batteries, which are the power source for cars. Therefore, a device to convert it to alternating current is required. It is an “inverter”.
One of the characteristics of inverters used to control the driving force of automobiles is that they can generate alternating current of various frequencies depending on the operating state of the motor. There is a proportional relationship between the frequency and the rotation speed of the rotating magnetic field, and the rotating magnetic field starts rotating at the same time as the stopped motor starts moving (starts rotating) (more precisely, the motor starts operating when the rotating magnetic field appears). .
