Brushless slotless DC permanent magnet motors are mechatronic products and require a dedicated driver to operate (usually in a star connection). The driver is an AC-DC-AC or DC-AC conversion system, which can be divided into a control circuit (including protection and position sensing circuits), a drive circuit (mainly power amplifier circuits), and a power supply circuit (including (rectifier) ​​filter circuits and power supply circuits for the system). The system block diagram is shown below. [IMG=System Block Diagram]/uploadpic/THESIS/2007/11/20071113153420219048.jpg[/IMG] Control Circuit: The control circuit controls the power devices (commonly MOSFETs, IPMs, etc.) in the drive circuit to control the start, stop, direction, braking, and speed of the brushless DC motor, and can provide overcurrent, overvoltage, and overheat protection. Initially, the control circuit used analog circuits, which were relatively simple to control and had good real-time performance. Digitizing the control circuit allows many hardware functions to be performed directly by software, reducing hardware circuitry and improving reliability. It also enhances the control circuit's anti-interference capabilities and provides intelligent interfaces, rich control functions, and联动 (interlocking) actions to meet diverse user requirements and improve product market adaptability. Currently, control circuits generally come in three forms: ASIC (Application-Specific Integrated Circuit), MCU (Microcontroller Unit), and DSP (Digital Signal Processor). For applications with low motor control requirements, using ASICs is a simple and practical method. DSPs offer faster processing speeds, fewer peripheral circuits, simpler system composition, and significantly improved performance, facilitating miniaturization and intelligence of drivers, making them suitable for more complex control requirements, but they are more expensive. MCU solutions can completely replace all the functions of ASICs, offering digital performance, fewer peripheral circuits, and lower cost, thus showing great application potential. Protection circuits in the control circuit can provide overcurrent, overvoltage, and overheat protection. These circuits are generally implemented in hardware but can also be combined with software. Modern intelligent power modules (IPMs) have also integrated some protection circuits. Position sensing circuits now mostly use Hall effect sensor circuits. The driver only needs to provide the corresponding circuit, and the Hall sensor can output the position signal of the motor rotor. Hall sensors are widely used because of their small size, increasingly lower price, and less demanding operating environment, unlike photoelectric sensors which are affected by environmental dust. With the further development of brushless DC permanent magnet motors, sensorless drivers have emerged. These drivers obtain the rotor position signal by detecting the back EMF of the motor windings, simplifying the motor structure and facilitating motor manufacturing. However, due to certain issues during load starting and low-speed operation, this type of driver is only used in applications with very strict requirements on motor size, infrequent starts and stops, stable loads, and relatively low reliability requirements. Drive circuit: The drive circuit is an important component of the AC-DC-AC or DC-AC conversion system. Controlled by the control circuit, it converts DC power into three-phase AC power, driving the motor's armature windings. The armature windings interact with the rotor permanent magnets, causing the rotor to rotate and converting electrical energy into mechanical energy. The drive circuit consists of power devices and a pre-drive circuit. Currently, the most commonly used power devices are metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), and intelligent power modules (IPMs). Transistors are rarely used due to their impact on system efficiency. Pre-drive circuits can be composed of discrete components, and many manufacturers now offer integrated chips for design selection. Drive circuits mostly operate in switching mode, allowing for convenient speed control, current limiting, and torque regulation of motors using pulse width modulation (PWM). With the rapid development of the semiconductor industry, many large semiconductor companies have integrated power devices, pre-drive circuits, and protection circuits, creating favorable conditions for modularization, intelligence, high-frequency operation, and miniaturization of drive circuits. Filtering circuits: (rectifier) ​​Filtering circuits rectify AC power into DC power, or directly filter the input DC power, and provide charging and discharging for the power devices in the drive circuit during transduction. They are a major component of the main circuit of AC-DC-AC or DC-AC conversion systems. Currently, many products add common-mode inductors, XY capacitors, and smoothing inductors to this part to reduce EMI interference and improve the power factor. Power Supply Circuit: The power supply circuit converts the filtered DC power into low-voltage DC power for use by the control and drive circuits. Most brushless drive products now use integrated switching power supplies, with many companies offering a variety of products to choose from. A few low-voltage brushless drive products use three-terminal regulators and transistors for voltage reduction. Brushless slotless DC permanent magnet motors differ significantly in structure from ordinary brushless DC permanent magnet motors, resulting in characteristics such as low inductance, low electromechanical time constant, good low-speed characteristics, high torque, low torque ripple, strong overload capacity, and high efficiency. Therefore, the drivers配套 (matched) with them must have appropriate control and protection measures.