How to achieve the speed regulation of a small DC motor by PMW is urgent

I'll send you the files I've used... Actually, there's no need to rush, just watch slowly and learn something. I was also very helpless at the time, and now that I think about the problems I will encounter in the future, this is nothing. So, be sure to stick to it.

Hope it helps、、、

Good luck buddy, reply to me when you receive the email...

This is not a question that can be addressed at this length. To put it simply, there is a PWM drive mode for AC motor speed regulation, and a PWM drive mode for DC motor speed regulation. The PWM speed regulation principle of AC motor mainly modulates a high-frequency square wave driving voltage through an AC low-frequency signal with variable frequency, so as to obtain a driving current in the motor armature that changes with the frequency of the modulation signal.

Therefore, the armature of the AC motor is driven by this current to generate a rotating magnetic field consistent with the frequency of the modulation signal, which changes the rotation speed of the motor rotor. The way it is modulated is frequency modulation. The PWM speed regulation principle of DC motor is different from that of AC motor, it does not adjust the speed of the motor by frequency modulation, but by adjusting the pulse width of the driving voltage, and cooperates with some corresponding energy storage elements in the circuit to change the amplitude of the voltage delivered to the armature, so as to achieve the purpose of changing the speed of the DC motor.

It is modulated in such a way that it is amplitude modulated.

How to use Arduino to control the speed regulation of DC motor through PWM pin?

Ordinary DC motors are insensitive to high-frequency components, and can be regarded as high-frequency signals plus low-pass filtering to drive motors.

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Extend a timing chip 8253There can be 3 timers, 2s implementation method: the timer sets the timing length to 50ms, counts in the timer interrupt, that is, let a variable, +1 in this interrupt, when this variable = 20, it is 1 second, the program judges whether this number = 20, if so, then jump to the reverse program, otherwise it is forward.

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Compared with general-purpose microprocessors used in personal computers, it emphasizes self-efficiency (without external hardware) and cost savings. Its biggest advantage is that it is small in size and can be placed inside the instrument, but the storage capacity is small, the input and output interface is simple, and the function is low. Due to its rapid development, the definition of the old microcontroller can no longer be satisfied, so it is called a wider range of microcontrollers in many applications; From the 80s of the last century, from the 4-bit and 8-bit single-chip microcomputers at that time, to the current 32-bit 300m high-speed single-chip microcomputer.

See if you can drive the chip so fast. Generally, 2K-20K frequency you have to time and output PWM, the timer is not enough, right? It is recommended to extend a timing chip 8253There can be 3-way timers.

2S implementation:

The timer sets the timing length to 50ms, and counts in the timer interrupt, that is, let a variable, +1 in this interrupt, when this variable = 20, it is 1 second, and the program determines whether this number = 20, if so, then jump to the reverse program, otherwise it is forward.

To change the steering of the DC motor, it can be achieved by changing the direction of the excitation current, or by changing the polarity of the armature voltage. For the speed regulation of PWM DC motor, the main circuit in the following figure can be used, with a suitable PWM drive, to change the rotation direction of the motor.

In the figure, the armature voltage of the motor is positive when it is positive and negative, and it is reversed when it is negative and right.

If you want the motor to rotate forward, you can apply a low level to the gate of V2 and V4 to turn off the source drain of V2 and V4. PWM drive is provided to the gate of V1 and V3, and the positive end of the power supply is connected to the negative end of the power supply through the source drain of V1 to the left end of the motor armature, and the right end of the motor armature is connected to the negative end of the power supply through the source drain of V3, and the motor rotates forward.

If the motor is reversed, the gate of V1 and V3 can be lowered to shut off the source drain of V1 and V3. PWM drive is provided to the gate of V2 and V4, and the positive end of the power supply is connected to the negative end of the power supply through the source drain of V4, and the left end of the motor armature is connected to the negative end of the power supply through the source drain of V2, and the motor is reversed.

1. The working principle of PWM.

The control mode is to control the on/off of the inverter circuit switching device, so that the output terminal obtains a series of pulses of equal amplitude, and uses these pulses to replace the sine wave or the required waveform. That is, multiple pulses are generated in half a cycle of the output waveform, so that the equivalent voltage of each pulse is a sinusoidal waveform, and the output obtained is smooth and there are few low harmonics.

By modulating the width of each pulse according to certain rules, the output voltage of the inverter circuit can be changed, and the output frequency can also be changed. In the PWM waveform, the amplitude of each pulse is equal, and when you want to change the amplitude of the equivalent output sine wave, the width of each pulse can be changed according to the same proportional factor, so in the AC AC inverter, the pulse voltage output by the PWM inverter circuit is the amplitude of the DC side voltage.

2. According to the above principle, after giving the frequency, amplitude and number of pulses in half a cycle of the sine wave, the width and spacing of each pulse of the PWM waveform can be accurately calculated. According to the calculation results, the on/off of each switching device in the circuit can be controlled, and the required PWM waveform can be obtained.

PWM control - pulse width modulation technology, by modulating the width of a series of pulses, to obtain the required waveform (including shape and amplitude) equivalentlyPWM control technology is the most widely used in inverter circuits, and most of the inverter circuits used are PWM type, and PWM control technology depends on the application in inverter circuits to determine its important position in power electronics technology.

1. Advantages of brushless motor:

a) Electronic commutation to replace the traditional mechanical commutation, reliable performance, no wear, low failure rate, life is about 6 times longer than that of brushed motors, representing the development direction of electric motors;

b) It is a static motor, and the no-load current is small;

c) High efficiency;

d) Small size.

Disadvantages: a) There is a slight vibration when starting at low speed, if the speed increases, the commutation frequency increases, and the vibration phenomenon is not felt;

b) **High, high controller requirements.

2. Advantages of brushed motors:

a) Smooth speed change, almost no vibration is felt;

b) Low temperature rise and good reliability;

c) **Low, so it is selected by more manufacturers.

Disadvantages: a) The carbon brush is easy to wear, it is troublesome to replace, and the life is short;

b) The running current is large, and the motor magnet is easy to demagnetize, which reduces the life of the motor.

The PWM speed regulation principle of DC motor is different from that of AC motor, it does not adjust the speed of the motor by frequency modulation, but by adjusting the pulse width of the driving voltage, and cooperates with some corresponding energy storage elements in the circuit to change the amplitude of the voltage delivered to the armature, so as to achieve the purpose of changing the speed of the DC motor. It is modulated in such a way that it is amplitude modulated.

The duty cycle of the PWM determines the average voltage output to the DC motor.

PWM is not current-regulated. PWM means pulse width adjustment, that is, to adjust the time ratio of high level and low level of square wave, a 20% duty cycle waveform, there will be 20% high level time and 80% low level time, and a 60% duty cycle waveform has 60% high level time and 40% low level time, the larger the duty cycle, the longer the high level time, the higher the output pulse amplitude, that is, the higher the voltage. If the duty cycle is 0%, then the high time is 0 and there is no voltage output.

If the duty cycle is 100%, then the full voltage is output.

Therefore, by adjusting the duty cycle, the purpose of adjusting the output voltage can be realized, and the output voltage can be continuously adjusted steplessly.

In brushless DC motors controlled with PWM, there are two ways of PWM control:

1.Using the PWM signal, control the on-time of the transistor, the longer the on-time, the longer the work time, the higher the speed of the motor.

2.The PWM control signal is used to control the on-time of the transistor, and the control voltage is changed to achieve useful CPWM SPWM....to regulate the speed.

Speed regulation is not only about changing the voltage (power supply voltage or control voltage), but also about changing the current. (The current of the control loop, not the current of the PWM signal).

I don't know if the landlord uses a DC motor controlled by a few phases PWM.

The PWM signal is a rectangular square wave, and its pulse width can be changed arbitrarily to change the output voltage of the pulse width control loop or the length of the work time to achieve stepless speed regulation.

DC motors are all directly energized to operate.

The fundamental speed regulation is to adjust the DC current, and through PWM debugging, different duty cycles are used to change the current size to achieve speed regulation.

When the DC motor is through the current, its power and torque are the largest. When the speed is lowered, the corresponding current, voltage, power, and torque will be reduced and reduced. Of course, you can't adjust the speed below the torque you need.