Changing the direction of the current of the DC motor can change the steering
To realize the steering control of DC motor, it is necessary to design a current commutation circuit, which can be designed by relay, transistor, MOS tube or DC motor driver chip.
Relays control the DC motor steering
Two single-pole double-system relays can form the positive and negative rotation control circuit of the DC motor. When SW1 and SW2 are disconnected, the two electrodes of the DC motor are connected to GND through the contact of the relay, and the DC motor stops rotating.
Dc motor is turning forward
Close the switch SW1, the relay K3 works, the electrode above the DC motor is connected to the VCC through the relay K3, the current flows from the top down through the DC motor, and the DC motor is turning
Close the switch SW2, the relay K4 works, the electrode below the DC motor is connected to the VCC through the relay K4, the current flows from the bottom up through the DC motor, the DC motor is reversed.
If SW1 and SW2 are both closed, the two electrodes of the DC motor are connected to the VCC via relays K3 and K4, and the DC motor stops turning.
Dc motor steering is controlled by triode or MOS tube
Two NPN triodes and two PNP triodes (or two N MOS tubes and two P MOS tubes) can form an H-bridge circuit (the component circuit is much like the letter \"H\") to control the forward and reverse of the DC motor.
When H1 is low, H2 is high, PWM1 is high, and PWM2 is low, Q1 and Q4 are on, Q2 and Q3 are off, and current flows through the DC motor from left to right to realize positive motor rotation. At this time, the speed of the DC motor can be controlled by changing the duty cycle of PWM1.
When H2 is low, H1 is high, PWM2 is high, and PWM1 is low, Q2 and Q3 are on, Q1 and Q4 are off, and current flows through the DC motor from right to left to achieve motor reversal. At this time, the speed of the DC motor can be controlled by changing the duty cycle of PWM2.
The motor drive chip controls the DC motor steering
It is only necessary to provide a level signal to the chip control pin to control the steering of the DC motor
In fact, the motor driver chip is also integrated with the H-bridge circuit, the driver chip is also integrated with overcurrent, overtemperature and other protection circuits, we only need to give two control pin signals, it is simpler to use, more efficient.
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There are two ways to change the rotation direction of a DC motor:
The first is armature reverse connection, that is, keep the polarity of the end voltage of the excitation winding unchanged, and make the motor reverse by changing the polarity of the end voltage of the armature winding;
The second is the field winding reverse connection method, that is, keep the polarity of the armature winding end voltage unchanged, by changing the polarity of the field winding end voltage to make the motor direction. When the voltage polarity of the two changes at the same time, the rotation direction of the motor is unchanged.
Separately excited and shunt excited DC motors generally use armature reverse connection to achieve positive and negative rotation. The reason why the field winding reverse connection method is not suitable for the separately excited and shunt excited DC motor is that the number of turns of the field winding is large and the inductance is large. When the field winding is reversed, a large induced electromotive force will be generated in the field winding. This will damage the insulation of the knife and the excitation windings.
1, separately excited DC motor
In general, the following two methods can be used to reverse the DC current machine:
(1) Reverse the voltage at both ends of the armature to change the direction of the armature current.
(2) Change the polarity of the field winding, that is, change the direction of the main magnetic field.
In actual operation, due to the number of turns of the field winding of the DC motor, the inductance is large, the field winding is disconnected from the power supply will produce a large self-induced electromotive force, so that the switch produces a large spark, and may also break down the insulation of the field winding. Therefore, the DC motor requiring frequent reverse should be reversed by changing the armature current direction.
In addition, it must also be pointed out that only one of the above methods can be used to achieve the motor reversal, if the two methods are used at the same time, the reverse is positive, but can not achieve the purpose of motor reversal.
2, permanent magnet DC motor
Permanent magnet DC motor, as long as the positive and negative connection direction of the power supply is changed, the motor can be reversed.
3, brushless motor
With a Hall-free controller, just swap any two motor lines.
Use a Hall controller, first adjust the Hall ac phase line, and then adjust the line package AB phase line.
4, series excited DC motor
It is necessary to change the direction of the stator coil in series with the carbon brush (rotor),
Assume that the internal wiring of the original motor is:
Power supply wire -- stator coil 1 end -- stator coil 2 end -- left carbon brush -- armature (rotor) -- right carbon brush -- power supply;
To change the direction, you need to change to:
Power supply wire -- stator coil 1 end -- stator coil 2 end -- right carbon brush -- armature (rotor) -- left carbon brush -- power supply;
The two ends of the carbon brush (or stator coil) can be switched.
The steering of the series DC motor is independent of the direction of the positive and negative connection of the power supply, and can actually be used on the AC circuit.
How to reverse the DC motor?
1?? Dc motor has two red and black input lines, for example, should +- correspond to each other, called positive rotation, but you put the positive and negative connection, it will reverse, but will not destroy the motor!
The 12V small fan in the charging box of the battery car we see, the small motor in the children's toys, and the vibration generated by your mobile phone calls are all DC motors.
2?? If you want to reverse the motor that is very simple, if it is a large power can be used six pile reversing switch, small power small six pile head small button switch. The middle two piles are connected to the motor, the upper two and the lower two are connected with the wire \"on\
3?? It can also be controlled by relays, such as air conditioners, refrigerators, and washing machines are completed by relays.
4?? You want to use the small contact button control to push the tripole dart or thyristor on to make the relay work. There are so many ways!
Thank you for reading?? !