What Is The Difference between BLDC Motor and Brushed DC Motor?

The Difference:

Working principle:

DC Brushless Motor:

The permanent magnets which are magnetized in the rotor of the motor, switch and detect the polarity of the motor rotor. The driver controls the start, stop and braking of the motor, the on and off of power tubes of the inverter.

DC Brushed Motor:

When the rotor rotates, the carbon brush slides on the commutator to generate a rotating field that is attracted to the static magnetic field of the stator. The current in the armature and stator windings, which is powered by battery or other DC power, to provide a constant DC voltage for battery or DC power.

Structural Construction:

BLDC Motor:

The motor consists of a motor and driver. The stator windings of the motor are mostly made of a three-phase symmetrical star connection method. The driver is composed of power electronics and integrated circuits, etc.

Brushed DC Motor:

The basic components of a DC brushed motor include a stator, a rotor, and a commutator. The stator and rotor magnetic fields interact to drive the motor to rotate.

Speed Difference:

Both motors are controlled by voltage regulation, but brushless DC motor uses electronic commutation, so the digital control is required. Brushed DC motor is commutated by carbon brush. Using Traditional analog circuits such as thyristors to complete the goal of commutation.

Brushed DC Motor:

The speed regulation process of brushed DC is realized by adjusting the power supply voltage. The adjusted voltage and current are converted by commutator and brush to change the strength of the magnetic field which is generated by the electrode to achieve the purpose of changing the speed.

Brushless DC Motor:

The speed adjustment process of the brushless motor is that the voltage is rated, changing the control signal of electric regulation, by a microprocessor to change the speed of the high-power MOS tube, to achieve the goal of changing speed. This process is called a variable frequency speed regulation.

BLDC Motor and Brushed DC Motor’s Advantage:

Brushed Motor:

1, Simple Structure, Mature Technology

Shortly after the birth of the brushless motor, people invented DC brushed motor. The motor has s simple mechanism, easy production, processing and control, convenient maintenance, large starting torque, so it has been widely used.

2, Fast Response, Large Starting Torque

The DC brushed motor has fast-starting response speed, large starting torque, smooth speed, almost no vibration from zero to maximum speed. For having high starting resistance, the power of brushless motors is small, the starting speed is relatively small, there is a buzzing sound during starting, and accompanied by strong vibration.

3, Running smoothly, Good starting and braking effects

The speed of the brushed motor is regulated by voltage, so the starting and braking are stable. BLDC motor is usually digital frequency-converted control. First, The AC is changed to DC, and then the DC is changed to AC. So during startup and braking, the brushless motor doesn’t run smoothly and the vibration is very large.

4, High Precision

Brushed DC motor is used together with gearboxes and decoder to have lager output power and higher control accuracy. All precision machine tools use this motor to control precision. In the startup and barking, the brushless DC motor is not stable. So the moving parts will stop at a different position each time. Only using position pins or limiters, the goal of precision position can achieve.

5, Low Cost, Easy Maintenance

Brushed DC motor has a simple structure, low production cost, and mature technology. If the motor fails, what you only need to do is to replace the carbon brush. Each carbon brush cost only a few dollars, which is very cheap. The technology of brushless motor is immature, high price.?

Brushless DC Motor:

1, NO Brush, Low Interference

The Brushless motor doesn’t have a carbon brush, which will not generate electric sparks in the running. Also, this greatly reduces interference for the remote radio equipment.

2, Low Noise, Smooth Operation

For not having brushes, the friction of operation process is greatly reduced and noise will be lower.

3, Long Life, Low Maintenance Cost

Without brushes, the wear of brushless motor is mainly on the bearings. From a mechanical point of view, brushless motors are almost maintenance-free motors. If it is necessary, what you should do is to remove dust.

How to distinguish Brushless DC Motor and Brushed DC Motor?

1, Appearance:

Generally, the brushless DC motor is flat(small power is also round), while the length of the brushed DC motor is longer than the diameter.

2, Lead-out Wire:

The rotor of the brushless DC motor needs not to have an external power supply, so there is no lead-out wire. While the brushed DC Motor requires extra power supply, so the two power lines are required.

3, Structure:

Disassemble the motor, having carbon, it is a brushed motor. Otherwise, it is a brushless motor.

4, Nameplate:

Generally, the manufacturers will mark the parameter on the motor nameplate. You can see the difference from it. For example, some brushless motor starts with the letters BLD, and the brushed DC motor is DK.