The control principle of DC geared motor, we know that motors are generally divided into motors and generators. Motors are devices that convert electrical energy into mechanical energy, and generators are devices that convert mechanical energy into electrical energy, the principle of motor operation is based on Faraday's law of electromagnetic induction.
When the motor carries out energy conversion, it must have two major components that can move relatively: the components that establish the excitation magnetic field and the induced components that induce electromotive force and flow through the working current.
Of these two components, the static one is called the stator and the rotating one is called the rotor.
Electromagnetic torque is generated by the interaction between the excitation magnetic field in the air gap and the magnetic field established by the current in the induced component.
Through the action of electromagnetic torque, the generator absorbs mechanical power from the mechanical system, and the motor outputs mechanical power to the mechanical system.
Different kinds of motors are formed due to different ways of establishing the above two magnetic fields.
Today we are going to talk about DC motors commonly used in the field of maker or DIY production of science and technology or in some conventional projects, which are commonly called DC motors or motors.
The internal structure of the DC motor, its fixed part (Stator)
On, a pair of DC-excited static main poles N and S are installed. In the rotating part (Rotor)The top is equipped with an armature core. There is an air gap between the stator and the rotor.
An armature coil formed by connecting two conductors A and X is placed on the armature core. The head and end of the coil are respectively connected to two circular-arc copper sheets, which are called commutating sheets.
The commutator is insulated from each other, and the whole composed of the commutator is called commutator.
The commutator is fixed on the rotating shaft, and the reversing piece and the rotating shaft are also insulated from each other.
A pair of fixed brushes B1 and B2 are placed on the commutator. When the armature rotates, the armature coil is connected to the external circuit through the commutator and the brush.
The operation principle of DC motor, if single chip microcomputer is used to control the motor with rated input voltage of 5 v, there is such a phenomenon: connect the two wires of the motor directly to the power supply, the motor moves, and then the two wires are connected in reverse, and the motor will reverse. Why is this?
The phenomenon mentioned above is also well explained. Look at the picture: If DC power is added to two brushes, DC current will flow in from brush A, pass through coil abcd, and flow out from brush B, according to the knowledge of electromagnetic induction, current-carrying conductors AB and cd will be affected by Ampere force, and their directions can be determined by the left-hand rule. The force on the two conductors forms a torque, make the rotor rotate counterclockwise.
Note that the external power supply is DC, but due to the effect of the brush and the commutator, the current flowing through the coil is AC, and the direction of the torque generated is unchanged.
If we set the direction of rotation as the positive direction, then when we adjust vcc and gnd, the reversal will be well explained, in fact, the direction of the Ampere force on the conductor rod is different. The principle is simply so much.
As for DC motors, we actually use controllers to control them. In fact, we only care about two things: how to adjust speed? How to control the direction of rotation? Let's talk about it in detail.
Speed Regulation and direction control of DC motor are one of the core control points of motor. In order to realize forward rotation and reverse rotation, we cannot frequently exchange VCC and GND, which is definitely unrealistic, so is there a circuit to help us achieve this function?
The answer is yes, this typical motor drive circuit is called'H bridge'Drive circuit.
It can not only control the rotation direction of the motor, but also adjust the speed.
There is another reason, we know that the IO driving ability of ordinary single chip microcomputer is insufficient, and it is possible to drive an led or buzzer, but it is not possible to drive a motor, in order to drive high-power load, we must use some other electronic components, which is the most important switching tube triode in the hardware field, so as to achieve the purpose of controlling large current with small current.
However, the driving ability of the triode is still relatively weak. The maximum current allowed to pass is only 800mA. It is only suitable for driving some toy cars. If you want to drive a higher power motor, it is necessary to replace the triode with a MOS tube with a larger working current.
Related reading: DC servo motor principle, AC servo motor manufacturers decrypt servo motor advantages tag dc geared motor control principle