Speed control for dc motor (electric motor) can be implemented using open loop or closed loop. Closed loop controller, also known as servo controller, or a feedback control, gives the best performance since the loop will maintain the actual speed to follow the reference. In simple application, an open loop controller can be enough if the load is constant, such as in fan control (PC fan speed control). This dc motor control circuit uses PWM (pulse width modulation), gives a better efficiency than using linear driver. Here is the schematic diagram of this PWM motor controller.
The circuit uses the very popular 555 IC, but here the circuit is configured in unusual way. The PWM output is taken from the discharge pin, an open collector point that should be pulled high using a Vcc-connected resistor, while the original output pin (pin 3) is functioned to discharge the timing capacitor. The recommended supply voltage for 555 IC is between 9-12 volt, and you can connect the +V motor to this 555 supply voltage if the motor use 9-12 volt. The frequency of this PWM controller is about 144Hz, and you can change the frequency by changin the C1 capacitor, use smaller caps for higher frequency. The motor current can be as high as 37A if you allow the MOSFET to rise its case temperature to 100 C, and you must provide enough heat sink to maintain the temperature below this point. It is a good idea to provide protector diode in parallel with the motor to short the back-emf generated by the DC motor that might cause a voltage spike that could burn the MOSFET. This simple pwm control gives you a variable speed drives for motion control application. [Circuit schematic diagram source: dprg.org]
Possibly Related Articles:
- Digital Encoder Circuit Using Stepper Motor
Using circuit depicted in the schematic diagram below, the direction and shaft rotation of stepper motor can be seen on the LED display. Alternative to digital rotation encoder as a... - Stepper Motor Controller
Stepper motor gives a simple, low cost, and accurate position control. Stepper motor can be driven by circuit mounted close to the motor, and controlled by a remote control circuit... - Permanent Magnet Motor Control with SCR
This is a schematic diagram of Permanent Magnet Motor Control circuit. This circuit is used to control the permanent magnet control. This circuit uses alternistor triac to enhance commutation characteristics... - 555 IC PWM Motor Control with Current Limiter
To provide rapid motor speed changes and motor direction reversal, four outputs drive a MOSFET H-bridge. N-channel devices are the lower rail power MOSFETs and P-channels are the upper MOSFETs.... - Servo Motor System Controller
This is a Servo System Controller circuit. This circuit is used to control a servo motor remotely. This circuit uses the 555 and requires only six extra components. Here is... - High Current Op-Amp for Motor Driver
The OPA2544 is a dual high-voltage/high-current operational amplifier. We can use it for driving a wide variety of high power loads. 2A output current is provided by this device and... - AC Mode Universal Motor Drive
This is AC mode universal motor drive circuit. This circuit is suitable for large range of application. It uses the microcontroller to interpret the user interface that is used to... - Closed Loop PWM Motor Control
Closed Loop Motor Control Closed loop (servo) control is used to make a constant speed motor control. Constant speed means that the speed of the motor will be kept constant... - 3 Phase AC Motor Speed Control
Controlling the speed of three phase ac motor is done by controlling the frequency of the power line supply, since the motor is synchronized with the line frequency. Three phase... - Simple Stepper Motor Controller
Stepper motor controller is needed to run a stepper motor, since a stepper motor cannot work by just connecting it to a power supply. To program a stepper motor to... - Small DC Motor Speed Controller
Electric motor has been widely used as motion control, and many type of motor controllers have been designed to provide variable speed drives for the motor. The best controller is... - LM378 24 V DC Proportional Motor Speed Control
National LM378 amplifier is used as a basis for economical proportional motor speed controller. This integrated circuit is able to deliver 700 mA continuous current for such DC motor applications...
| 
