Do you know the difference between a brush and a brushless 48V electric vehicle controller?
At present, the ratio of brushed motors used in electric vehicles is gradually reduced, and brushed motors are only used on partial load tricycles. Two-wheel electric vehicles have completely eliminated brushed motors. The brush motor is different from the brushless motor structure. The disadvantage of the brush motor is high energy consumption and troublesome maintenance. The advantage is high power and high torque. The structure is different, and the controller principles are different. The brush motor controller is simple, the current can be directly controlled, and the price is cheap.
The price of the 1500w controller will not exceed one hundred yuan. The principle of the brushless controller is slightly complicated, and the original parts used are relatively high, and the cost is high. The price of the 1500w controller is about 300 yuan or higher. Not common between the two! Let's take a look at the brush controller circuit diagram:
The principle of speed regulation is to adjust the duty cycle of the switching transistor through the pwm chip, the duty ratio is high, and the motor speed is high. The duty cycle is low and the motor speed is low. The duty cycle can be understood as the conduction ratio of the triode, which can be understood as a switch, faucet. The opening and closing time is different, and the final water flow is also different, thus achieving the purpose of adjusting the current, and thus achieving the purpose of speed regulation. Let's take a look at the brushless controller:
The brushless controller has more functions than the brush controller, and the principle is more complicated. Let's look at the circuit diagram:
The brushless controller replaces the mechanical commutator of the brushed motor with an electronic commutator, so the circuit is more complicated, and it is more intelligent with a single-chip microcomputer, such as with a finite current/overcurrent detection circuit, which can be effective. Avoid the dangers caused by super flow. The brushless motor has no carbon brush, the rotor uses permanent magnet material, and the stator uses three-phase coils. Therefore, in order to rotate the permanent magnet rotor, a rotating magnetic field must be provided. As long as the three sets of coils are energized in sequence, a rotating magnetic field can be obtained. Therefore, the electric vehicle brushless controller obtains the rotating magnetic field by controlling the triode switch, and the control part is as follows:
Controlling six (high power will be many) transistors in a certain order can make the ABC winding wheel flow, so that the commutation, a rotating magnetic field, to drive the permanent magnet rotor rotation. For example, VT1 and VT2 are turned on, VT2 and VT3 are turned on, VT3 and VT4 are turned on, VT4 and VT5 are turned on, VT5 and VT6 are turned on, and VT6 and VT1 are turned on, so that the AC, BC, and AB windings are energized in turn, that is, A rotating magnetic field is generated.