Most brushless motors on the market use Hall sensors to sense position and are controlled by sinusoidal wave controllers for normal operation. However, as power switch drivers, consideration must be given to safety protection for current and voltage, as power devices are more delicate than simple brushes. Further optimization of the drive can be done to improve performance according to the operating conditions. Other methods for starting and using brushless motors are also available, each yielding different effects depending on specific requirements. Below are a few simple introductions to some methods:
Frequency and Voltage Boost Synchronous Start Method：
- This method is based on the frequency conversion start of a synchronous motor. PWM waveforms are generated by the DSP’s built-in event manager to control the inverter. Initially, the motor is pulled into synchronization, and the inverter’s commutation frequency gradually increases while the stator voltage of the brushless motor starts small and gradually increases. This allows the motor to gradually increase its rotor speed, achieving a start similar to that of a permanent magnet synchronous motor.
External Synchronous Three-Stage Open-Loop Start Method：
- This method includes rotor pre-positioning, external synchronization acceleration, and self-synchronization. Initially, any two phases of the stator are turned on while the other phase is turned off, and the motor obtains the corresponding position through two pre-positioning steps. Then, external synchronization of the rotor occurs, followed by a switch to self-synchronization when the speed of the brushless motor reaches a certain value, enabling determination of the rotor position.
Short-Term Detection Pulse Rotor Positioning Start Method:
- This method relies on the permanent magnet rotor’s magnetization and demagnetization effects on the iron core of the stator winding, thereby increasing or decreasing the inductance of the stator winding. This method involves pre-positioning, acceleration, and switching processes, but differs from the pre-positioning and acceleration methods mentioned above.
Pre-Positioning Start Method:
- In this method, a predetermined energized state is applied to the stator when the brushless motor starts, causing the rotor to rotate to a predetermined initial position. Then, the motor’s energized state is changed, and under the action of electromagnetic torque, the rotor rotates to the next predetermined position. During this rotation, the motor is switched to brushless motor operating mode, and the rotor position is detected using back electromotive force.
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These methods provide various options for starting and using brushless motors, catering to different requirements and scenarios.For inquiries or assistance with brushless motors and related solutions, contact Faradyi Technology Co., Ltd, a leading high-tech enterprise specializing in the development and production of high-performance, high-quality DC brushless motors, DC servo motors, stepper motors, and associated driver controllers for global industrial automation.
