how electric cars work
Inside the electric vehicle, the heart of the electric vehicle is a combination of the following: the controller takes power from the battery and delivers it to the motor.
A pair of potentiometer for accelerator pedal hooks (
Variable resistance)
These potentiometer provide a signal telling the controller how much power it should provide.
The controller can provide zero power (
When the car stops), full power (
When the driver steps on the accelerator pedal)
Any power level.
When you open the hood, the controller usually dominates the scene, as you can see here: in this car, the controller accepts 300 v dc from the battery pack.
It converts it to a maximum of 240 v ac, three-
Phase, sent to the motor.
It uses very large transistors to achieve this, which can quickly turn on and off the voltage of the battery, resulting in a sine wave.
When you press the accelerator pedal, the cable on the pedal is connected to these two potentiometer: the signal from the potentiometer tells the controller how much power is delivered to the motor of the electric vehicle.
There are two potentiometer for safety.
The controller reads two potentiometer and ensures that their signal is equal.
If not, the controller will not run.
This arrangement prevents the potentiometer from being full-on position.
The work of the controller in DC electric vehicles is easy to understand.
Let\'s assume that the battery pack contains 12 12-
Volt battery, 144 v in a string.
The controller accepts 144 v dc and delivers it to the motor in a controlled manner.
The simplest DC controller is a large/off switch connected to the accelerator pedal.
When you press the pedal, it turns on the switch and it turns off when you remove the foot from the pedal.
As a drive, you have to push and release the accelerator to turn the motor pulse on and off in order to keep the given speed.
Obviously this on/off approach works, but it can be painful to drive, so the controller will do the pulse for you.
The controller reads the setting of the accelerator pedal from the potentiometer and adjusts the power accordingly.
Let\'s say you push the throttle in half.
The controller reads the setting from the potentiometer and quickly switches the power supply to the on and off of the motor so that it is turned on half the time and off half the time.
If your accelerator pedal drops by 25%, the controller will pulse power, so it turns on in 25% of the time and turns off in 75% of the time.
Most controllers pulse power more than 15,000 times per second in order to keep the pulses outside the range of human hearing.
The pulse current causes the motor housing to vibrate at this frequency, so by taking more than 15,000 periodic pulses per second, the controller and the motor are silent to the human ear.
This work is a bit complicated in the AC controller, but it is the same idea.
The controller creates three artifactssine waves.
It does this by taking out the DC voltage from the battery and turning it on and off.
In the AC controller, 60 reverse voltage polarity is also required per second.
Therefore, six sets of transistors are actually needed in the AC controller, while only one set of transistors is required in the DC controller.
In the AC controller, for each phase, you need a set of transistors to pulse the voltage and a set of transistors to reverse the polarity.
You copied it three times in three stages. -
A total of six transistors.
Most DC controllers used in electric vehicles come from the electric forklift industry.
The Hughes ac controller seen in the above figure is the same type of AC controller used in General Motors/Saturn electric vehicles
1 electric car.
It can provide a maximum power of 50,000 watts for the motor.