Permanent magnet motor drive systems primarily fall into two categories: synchronous motors used for asynchronous starting and motion control systems and transmissions. The former is mainly for energy saving, as permanent magnet synchronous motors have higher efficiency and power factor than asynchronous motors. Their power supply is 50Hz three-phase AC, but synchronous motors cannot be directly started at high frequencies; a starting winding must be placed on the rotor. The latter requires speed regulation and a dedicated power conversion device, commonly known as a frequency converter or driver. Permanent magnet motor drive systems smaller than 5kW are mostly used for servo control, controlling the torque, speed, position, acceleration, and even the rate of change of acceleration to improve the dynamic process of the application system. In Japan, these low-power application systems are called mechatronic systems, while in Europe and America they are called motion control systems. Larger power systems, ranging from 5kW to 30kW, are generally called transmission systems because these systems primarily control the speed, position, and acceleration/deceleration of the system, which are not critical indicators. In my country, motion control systems and transmission systems of tens of kilowatts are generally referred to as drive systems. Permanent magnet motors used in the second category mentioned above are often called permanent magnet brushless motors. Based on the current or potential waveform, they can be divided into brushless DC and brushless AC types. Replacing the brushes and commutator of a DC motor with an inverter and position sensors, and placing the armature windings on the stator and moving the magnetic poles to the rotor, results in a brushless DC motor. Rotor heating is significantly improved. The sensors use Hall elements or photoelectric devices, generating a position signal every 60° electrical angle of rotor rotation. Only two phases of the winding are conducting at any given moment, i.e., a 120° energization mode. The winding current is a square wave or trapezoidal wave, and the control software is simple. Brushless AC motors, also called permanent magnet synchronous motors, have sinusoidal winding currents and often employ field-oriented control, also known as vector control. The sensors are relative or absolute encoders with resolutions ranging from hundreds to thousands of pulses per revolution. Therefore, brushless DC motors are mostly used in speed regulation applications, while permanent magnet synchronous motors are mostly used in servo systems such as speed and position control. In speed control systems below 30kW, permanent magnet motor speed control systems have the following advantages compared to asynchronous motor speed control systems: (1) Energy saving: Since the winding current of an asynchronous motor includes the excitation current component, the efficiency of a permanent magnet motor is higher than that of an asynchronous motor for the same power. (2) Controllability: The DC brushless motor controlled by square wave has a faster speed response than the asynchronous motor controlled by constant open-loop control. The field-oriented control of a permanent magnet synchronous motor is simpler than that of an asynchronous motor, and its control performance is less affected by changes in motor parameters. (3) Material saving: The power density of a permanent magnet motor is higher than that of an asynchronous motor. For the same output power, the frame size is significantly reduced, and the savings in materials such as silicon steel sheets and enameled wire make up for the cost of permanent magnet materials in the permanent magnet motor. In recent years, with the adjustment and upgrading of my country's industrial structure, a large number of motor drive systems are needed. Whether it is a situation where an asynchronous motor was originally used to operate at a constant speed or a situation where an asynchronous motor speed control system was already in use, switching to a permanent magnet motor drive system has its unique advantages. The 550W servo system for industrial sewing machines and the 1000Nm drive system for oilfield screw pumps are two typical applications of this type of system. However, industrial sewing machine manufacturers and screw pump manufacturers only possess the application technology and lack the capability to develop drive systems. The manufacturing and design of general-purpose asynchronous motors can be completed by domestic motor manufacturers, and these processes are already standardized and serialized. The design and manufacturing of permanent magnet motors are still in their infancy, and motor manufacturers lack the development and production capabilities for drive and control components. General-purpose frequency converters are not suitable for specific permanent magnet motors and application processes, and frequency converter manufacturers are unwilling to invest effort in this segment of users who are just beginning their research and development. This situation is much better for asynchronous motor speed control systems. Drives and motors can be purchased on the market; users only need to develop a controller, which in some cases is a general-purpose PLC, and then write the corresponding process software. Therefore, to accelerate the research and development and industrialization of permanent magnet motor drive systems, an integrated development strategy must be adopted. Integrated development is not the same as system integration; the latter involves connecting mature components into a system through appropriate hardware or software to complete a specific process. When individual components are still immature, it is necessary to comprehensively consider and focus on key research and development based on system objectives; this is a characteristic of integrated development. In Japan and Europe, leading power electronics and microcontroller technologies have promoted the development of motor drive systems, and manufacturers have the capability to conduct integrated research and development of these three components. my country's development and application of permanent magnet motor drive systems are still in their initial stages. How to learn from foreign experience, leverage the respective advantages of research institutions, manufacturers, and users, strengthen the connections among them, overcome technical bottlenecks, and quickly promote the application of this technology is worthy of consideration and exploration from all sides. This article analyzes the current situation of my country's research and development and promotion of permanent magnet motor drive systems, and from the perspective of integrated development of permanent magnet motors, drives, and controls, introduces permanent magnet motor drive systems applied to industrial sewing machines and oilfield screw pump drives. Finally, it discusses some key technologies for the development of permanent magnet motor drive systems in my country. II. Permanent Magnet Synchronous Servo System for Industrial Sewing Machines my country is a major garment producer and a major sewing machine producer. The vast majority of the world's industrial sewing machines are manufactured in my country, with flatbed sewing machines being the main type of industrial sewing machine, with an annual output of over 3 million units. To date, over 85% of flatbed sewing machines still use asynchronous motors with speed regulation via electromagnetic slip clutches, which have the following main shortcomings: (1) low efficiency of the speed regulation system; (2) inability to adapt to new sewing functions, such as automatic thread trimming, back and forth backstitching, thread feeding, and needle position control. To overcome these shortcomings, the electromagnetic slip clutch must be removed, and the load must be directly driven by the motor. The new permanent magnet synchronous servo system must have speed and position control functions, with the following specific indicators and functions: (3) wide operating range, from 200 to 6000 r/min; (4) fast speed response; (5) position accuracy within ±3°; (6) zero electromagnetic torque in standby mode, allowing the operator to rotate freely. If a servo system that meets the above conditions is developed using conventional thinking, that is, the centralized control structure shown in Figure 1, then the sewing machine manufacturer first purchases the servo motor and driver, and then develops the control part themselves. As mentioned earlier, sewing machine manufacturers currently lack the capability or full capability to develop the control system. Crucially, the servo motor and driver, around 500W, are imported, costing over 4000 RMB, significantly higher than the 1600 RMB price of domestically produced systems developed using an integrated development approach. Figure 2 shows a flatbed sewing machine servo system designed according to the integrated development concept. The difference from Figure 1 lies in the roles of the controller and driver. In Figure 1, the driver only controls the permanent magnet motor, with real-time control handled by the controller. In Figure 2, the controller's real-time tasks are greatly reduced, but the driver's tasks are increased. The controller only handles display, keyboard, storage, and communication functions. The driver, in addition to controlling the permanent magnet motor's magnetic field orientation, also triggers corresponding electromagnet actions based on received commands and needle bar position, performing auxiliary functions such as thread cutting, backstitching, and thread pulling. Because the driver's control chip, especially in magnetic field orientation control, uses a fast digital signal processor (DSP), these auxiliary functions do not affect the control of the permanent magnet motor. However, the requirements for the microprocessor in the controller are much lower; a typical 8-bit microcontroller suffices. Figure 3(a) shows the 550W servo motor used in a flatbed sewing machine. A photoelectric encoder is mounted on the rear cover, and the surface-mounted magnetic steel structure ensures the motor operates with a high power factor. The fractional-slot winding effectively suppresses tooth harmonics, reducing vibration and noise. Figure 3(b) shows the driver. Power devices utilize power modules, improving reliability. The control chip is a DSP, ensuring data processing capabilities for magnetic field orientation control. Figure 3(c) shows the controller, also known as the mode box, which accepts and stores operator commands. Its laptop-style human-machine interface is simple to operate and provides a comfortable user experience. After years of development and improvement, this type of system has reached an application scale of nearly 300,000 units per year in flatbed sewing machines and also has a certain usage in special sewing machines. Three-way direct-drive screw pump drive systems: Oilfield pumps generally come in three forms: submersible pumps, beam pumping units, and screw pumps. Screw pump oil extraction units are suitable for sandy, gas-containing, and viscous oil applications, offering advantages such as energy saving and small footprint. Screw pumps can be used in almost all oil wells with a pumping depth not exceeding 1500m. Screw pump oil extraction machines have been widely used in Daqing Oilfield, and other oilfields are also actively promoting them. However, the traditional screw pumps currently in use still have the following shortcomings: (1) easy to break the rod: when anomalies occur downhole or the surface outlet pipeline is blocked, the pump rod may break due to the inability to reduce speed, the reduction gear may break, and the motor may burn out; (2) large maintenance of the mechanical transmission part; (3) reverse tripping: the nearly 1,000-meter-long pump rod, with the added torque, causes elastic deformation in the circumferential direction of the pump rod. When the machine stops, the high-speed reverse rotation caused by the elastic recovery of the pump rod causes tripping; (4) the transmission efficiency is still low: the asynchronous motor used in the screw pump is the same as that of the beam pumping unit, which is a large horse pulling a small cart. The power factor is about 0.4, and the efficiency of the asynchronous motor is about 75%. Considering the belt and reduction gear, the transmission efficiency is less than 65%; (5) it is difficult to change the running speed of the screw pump: only the size of the pulley can be changed or the motor winding can be reconnected. Replacing the asynchronous motor with a DC brushless motor can overcome the above shortcomings. Smooth speed regulation is achieved through a driver, with a speed range of 0–250 r/min, a rated torque of 1000 Nm, an overload capacity of 4 times, and a rated efficiency of 91%, reaching 88% even at 1/3 load. The motor directly drives the oil pump, eliminating belts and reduction gears, significantly improving transmission efficiency, and eliminating the need for maintenance of the mechanical transmission components. The controller features a human-machine interface, allowing oilfield workers to easily adjust the screw pump's operating speed according to well conditions. The permanent magnet brushless DC motor drive system also solves the decades-old problem of screw pump shutdown braking. Traditional mechanical brakes have two types: one is the ratchet anti-reverse method, which is simple in structure but has poor reliability, and the elastic energy stored in the pump rod cannot be released; the other is the reverse hydraulic suppression method, which is reliable but costly and complex in structure. The permanent magnet brushless DC motor drive system can brake through electrical control. The control box contains an energy-consuming resistor and an independent brake controller. When the pump stops or the system loses power, the pump rod elastically releases, driving the motor to reverse. The motor is in generator mode, and the brake controller activates. The faster the pump rod speed, the greater the electromagnetic braking torque, ultimately returning the pump rod to its initial state for easier restarting or well workover. Additionally, the drive unit can control and identify load torque, judging overload or light load abnormalities and reducing the occurrence of rod breakage. In the direct-drive screw pump drive system, the low-speed, high-torque permanent magnet brushless DC motor is specially developed based on the load characteristics of the screw pump. The driver hardware is similar to that of an asynchronous motor driver of equivalent capacity, but the software is specifically designed for brushless DC motor control. The brake control function is also integrated into the driver, which is difficult to achieve with general-purpose frequency converters. This application again demonstrates the practical significance of integrated development of permanent magnet motors, drivers, and controllers. Four key technologies: Variable frequency speed control of asynchronous motors. my country started late, and the control models for asynchronous motors and the design level of high-power frequency converters lag behind those abroad. The permanent magnet motor drive system provides us with opportunities. First, my country has abundant rare earth reserves. Second, research on permanent magnet motor drive systems is not widespread abroad, and applications are limited. Third, the controllability of permanent magnet motors is important. To popularize the application of permanent magnet motor drive systems, we must tackle some key and common technologies, specifically: (1) Controller: The hardware technology is the most mature, easiest to implement, and fastest to show results. However, PLCs are currently widely used, and they are imported products with high prices, which is not conducive to forming products with independent intellectual property rights in my country. How to replace PLCs with a system composed of microcontrollers as the core, with comparable performance and reliability and significantly reduced prices, is a problem that needs to be solved in terms of hardware. In addition to establishing simple and easy-to-learn development platforms for different application fields, it is best to establish a relatively simple and universal application language and algorithm. (2) Motor: We should study the structure, manufacturing process, materials, and electromagnetic design of the motor, and formulate corresponding industrial standards when appropriate. For motors used in special applications such as low speed and high torque, periodically changing loads, potential energy loads, and large inertia loads, we should focus our efforts on their development. These are products that are in short supply in the market. (3) Sensors: These are the main components in the control system. The magnetic field orientation control of the motor requires current and position sensors. Other types of sensors are also needed in the motion control system. Although my country can produce a considerable number of types of sensors, there is still a certain gap in performance. This should be given full attention. Existing sensors can be selected or integrated, while new sensors need to be developed. (4) Drivers: These are the bottleneck restricting the industrialization of servo motion systems. There are three main reasons. First, it is difficult to implement complex and accurate motor models on traditional microcontrollers. The emergence of digital signal processors (DSPs) has taken a big step forward in solving this problem. However, the popularity of DSPs is still insufficient. The practical problems that control algorithms need to solve include sensorless algorithms, the smooth operation of motors at low speeds, and the fast response of the system. Secondly, the reliability of power electronic devices and the level of system design are low. The development of intelligent power modules (IPMs) and dedicated intelligent power modules (ASIPMs) has enabled general technicians to design low-power electronic circuits, but the design and reliability of high-power electronic circuits still require systematic research. The integrated development of permanent magnet motor drive systems involves numerous technologies, which cannot be completed by a few people or those specializing in a particular field. Especially in the early stages, the system structure is similar to the distributed system in Figure 2, involving technologies in motors, mechanics, power electronics, control, and applications. Achieving industrialization requires not only overcoming technical difficulties but also establishing a reasonable mechanism to stimulate the enthusiasm of R&D, manufacturing, and application. Exploration in this area is particularly urgent and important. Fifth, in conclusion, the integrated development strategy for permanent magnet motor drive systems is proposed in response to the current situation in this field in my country. In the past five years, we have consistently implemented this strategy in our R&D and have achieved some results. The 550W industrial sewing machine servo system and the 1000Nm direct-drive screw pump drive system are manifestations of this strategy. The continuous application and promotion of permanent magnet motor drive systems has also brought new opportunities to the motor industry. From the design and processing of permanent magnet motors to the development and manufacturing of drivers, and then to the search for and expansion of application fields, how various enterprises participate in this process will bring profound changes to them.