Jul 03, 2017
DC motor has a fast response, a large starting torque, from zero speed to rated speed with rated torque can provide the performance, but the advantages of DC motor is also its shortcomings, DC Brush Motor because the DC motor to produce a constant load under constant load Moment performance, then the armature magnetic field and rotor magnetic field to be constant to maintain 90 °, DC Brush Motor which will be by the carbon brush and commutator. Carbon brushes and commutators produce sparks when the motor rotates, and the toner is limited in addition to damage to the components.
AC motor without carbon brush and commutator, DC Brush Motor maintenance-free, strong, wide application, but the characteristics of the DC motor to achieve the equivalent of the performance of complex control technology to be used to achieve. Now the rapid development of semiconductor power components to switch the frequency to speed up a lot, to enhance the performance of the drive motor. DC Brush Motor Microprocessor speed is faster and faster, can be achieved AC motor control placed in a rotating two-axis orthogonal coordinate system, DC Brush Motor the appropriate control of AC motor in the two-axis current component, to achieve similar DC motor control and DC motor equivalent performance.
In addition, many microprocessors will control the necessary functions of the motor in the chip, and the volume is getting smaller and smaller; like analog / digital converters (Analog-to-digitalconverter, ADC), pulse width modulation (pulsewidemodulator, PWM) ... Wait. DC brushless motor that is electronically controlled AC motor commutation, similar to the DC motor characteristics and no DC motor mechanism on the lack of an application.
DC brushless motor is a synchronous motor, DC Brush Motor that is to say the motor rotor speed by the motor stator rotation magnetic field speed and the number of rotor (P): N = 120. F / P. In the case of a fixed number of rotors, changing the frequency of the stator's rotating magnetic field can change the rotational speed of the rotor. DC brushless motor is the synchronous motor with electronic control (drive), DC Brush Motor control the stator rotation magnetic field frequency and the motor rotor speed back to the control center repeated correction, DC Brush Motor in order to achieve close to the DC motor characteristics of the way. That is, DC brushless motor can be in the rated load range when the load changes can still control the motor rotor to maintain a certain speed.
The power supply section can be directly connected to a DC input (typically 24V) or at an AC input (110V / 220V). If the input is AC, it must be converted to DC by converter. Either DC input or AC input to be transferred to the motor coil before the DC voltage from the inverter (inverter) into three-phase voltage to drive the motor. DC Brush Motor Inverter (Q1, Q3, Q5) / lower arm (Q2, Q4, Q6) connected to the motor as the control of the flow through the motor coil switch. The control section provides PWM (pulse width modulation) to determine the frequency of the switching of the power transistor and the commutation of the inverter. DC brushless motors generally want to use when the load changes in the speed can be stabilized at the set value without changing the speed of control, so the motor is equipped with a magnetic field inside the hall sensor (hall-sensor), DC Brush Motor as the speed Closed loop control, but also as a basis for phase control. DC Brush Motor But this is only used as a speed control and can not be used as a positioning control.