An induction motor is almost equally efficient from zero all the way up to around 18, rpm. Like most EVs, Model S uses a simple single-speed transmission. EVs do have a few components that ICEs lack. An inverter is needed to convert the DC current from the battery pack to the 3-phase AC used by the motor.
The inverter also controls the speed of the motor. This allows metallic tubes filled with glycol coolant to snake through the gaps between the cells, keeping the battery cool and extending its life. Battery packs are necessarily large and heavy. Power electronics controller: This unit manages the flow of electrical energy delivered by the traction battery, controlling the speed of the electric traction motor and the torque it produces. Thermal system cooling : This system maintains a proper operating temperature range of the engine, electric motor, power electronics, and other components.
Traction battery pack: Stores electricity for use by the electric traction motor. Transmission electric : The transmission transfers mechanical power from the electric traction motor to drive the wheels. This process happens when your foot is on the accelerator - the rotor gets pulled along by the rotating magnetic field, requiring more torque.
But what happens when you let off of the accelerator? When your foot comes off the accelerator, the rotating magnetic field stops and the rotor starts spinning faster as opposed to being pulled along by the magnetic field.
When the rotor spins faster than the rotating magnetic field in the stator, this action recharges the battery, acting as an alternator. To further simplify this process - imagine pedaling a bike up a hill. To get to the top of the hill, you need to pedal harder and may even have to stand up and expend more energy to rotate the tires and reach the peak of the hill. This is similar to pressing down on the gas. The rotating magnetic field pulling the rotor behind it creates the resistance or torque needed to move the tires and car.
Once at the peak of the hill, you can take it easy and recharge while the wheels move even faster to take you down the hill. In the car, this happens when you let your foot off the gas and the rotor moves faster and feeds electrical energy back into the power line to recharge the battery.
The conceptual differences behind these two types of currents is seemingly fairly obvious. While one current is consistent, the other is more intermittent. The term direct current refers to electricity that moves in a singular and consistent direction at all times. Think of how batteries have clearly defined positive and negative sides to them. They use direct currents to send the same voltage out on a consistent basis. In addition to batteries, fuel cells and solar cells also produce direct currents, while simple acts like rubbing certain materials together can produce DC as well.
In keeping with our battery concept, when considering the positive and negative sides of the battery, it is important to note that the direct current always flows the same direction between the positive and negative side. This ensures that both sides of the battery are always positive and negative. The term alternating current defines a type of electricity characterized by voltage think water pressure in a hose and current think rate of water flow through the hose which vary with respect to time.
As the voltage and current of an AC signal change, they most often follow the pattern of a sine wave in the image above, the sine wave is shown in the right voltage graph. Due to the waveform being a sine wave, the voltage and current alternate between a positive and negative polarity when viewed over time.
The sine wave shape of AC signals is due to the way in which the electricity is generated. Another term you may hear when discussing AC electricity is frequency. The frequency of the signal is the number of complete wave cycles completed during one second of time.
Frequency is measured in Hertz Hz and in the United States, the standard power-line frequency is 60 Hz. This means that the AC signal oscillates at a rate of 60 complete back-forth cycles every second. AC electricity is the best way to transfer useable energy from a generation source i. This is due to the alternating nature of the AC signal which allows the voltage to be easily stepped up or stepped down to different values.
This is why your home's outlets will say volts AC safer for human consumption but the voltage of a distribution transformer which supply power to a neighborhood those cylindrical grey boxes you see on the power line poles , might have voltage as high as 66 kVA 66, volts AC.
AC power allows us to construct generators, motors, and distribution systems from electricity that are far more efficient than direct current, which is why AC is the most popular energy current for powering applications. Most large, industrial motors are induction motors and they are used to power diesel trains, dishwashers, fans, and countless other things.
In technical terms it means that the stator windings induce a current to flow into the rotor conductors. Whenever you have a stator that houses multiple unique windings per motor pole, you are dealing with polyphase.
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