BLOG

DC brushless motor constant power speed regulation mode

Is the so-called weak magnetic speed regulation, this mode of speed regulation, the essence is a constant torque speed regulation mode of a supplement, mainly is some occasions, the need for a wide range of speed regulation, such as some gantry bed, the need for DC brushless motor processing when feeding is very slow, torque to be very high;And back when the torque is very light is to run very fast, at this time when the knife with constant torque speed regulation mode, and back when the weak magnetic speed regulation mode, at this time the maximum power of the motor is the same.

There are also some electric vehicles, low speed uphill to run very slow, need a lot of torque, and flat road resistance is small and want to run very fast, this time also need to use constant power speed regulation, similar to the way of mechanical shift or speed ratio adjustment to speed regulation.General weak magnetic speed regulation, is not suitable for permanent magnet motor, so the magnetic flux Φ can not be controlled separately.
To weaken the magnetic field, is to directly reduce the size of the air gap flux Φ, at this time can reduce the current of the excitation coil, usually in the excitation coil will use silicon controlled or field effect tube these to do a PI adjustment back to output a current source to achieve.
When the weak magnetic speed regulation, the higher the motor speed, the smaller the maximum torque output of the motor, which is to be noted, and generally not unlimited reduction, can probably be controlled at about 90% of the rated excitation current.