Modern AC servo system has experienced the transformation from analog to digital. Digital control loop has been everywhere, such as commutation, current, speed and position control. It is not surprising that new power semiconductor devices, high-performance DSP plus FPGA, and dedicated servo module are used. The servo products of international manufacturers will be replaced every 5 years, new power devices or modules will be updated every 2-2.5 years, and new software algorithms will be changing with each passing day. In short, the life cycle of products is getting shorter and shorter. Summarizing the technical and product routes of servo manufacturers at home and abroad, combined with the changes of market demand, we can see some of the latest development trends as follows:
Although the work in this area has been carried out for a long time, it still needs to be strengthened. It mainly includes the high efficiency of the motor itself, such as the improvement of permanent magnet material performance and better magnet installation structure design, as well as the high efficiency of drive system, including the optimization of inverter drive circuit, acceleration and deceleration motion, regenerative braking and energy feedback, and better cooling mode.
Direct drive includes rotary table servo drive with disc motor and linear servo drive with linear motor. Because of eliminating the intermediate transmission error, high speed and high positioning accuracy are realized. The linear motor is easy to change its shape, which can make all kinds of devices with linear mechanism realize miniaturization and lightweight.
High speed, high precision and high performance
Using higher precision encoder (million pulse per revolution), higher sampling accuracy and data bits, faster DSP, high-performance rotary motor and linear motor without cogging effect, as well as various modern control strategies such as self-adaptive and artificial intelligence are used to continuously improve the index of servo system.
Integration and integration
The vertical integration of motor, feedback, control, drive and communication has become a development direction of low power servo system. Sometimes we call this kind of motor integrated with drive and communication as smart motor, and sometimes we call the driver integrated with motion control and communication as intelligent servo driver. The integration of motor, drive and control makes them more closely integrated from design, manufacture to operation and maintenance. However, this method is faced with greater technical challenges (such as reliability) and the challenges of engineers’ usage habits, so it is difficult to become the mainstream, and it is a small characteristic part in the whole servo market.
The universal driver configuration has a large number of parameters and rich menu functions, which is convenient for users to set V / F without changing the hardware configuration Five working modes, including control, speed sensorless open-loop vector control, closed-loop flux vector control, permanent magnet brushless AC servo motor control and regeneration unit, are suitable for various occasions, and can drive different types of motors, such as asynchronous motor, permanent magnet synchronous motor, brushless DC motor, stepper motor, and can also adapt to different sensor types or even no position transmission Sensilla. The feedback of the motor can be used to form a semi closed-loop control system, or a high-precision full closed-loop control system can be formed with the external position or speed or torque sensor through the interface.
Modern AC servo drivers have the functions of parameter memory, fault self diagnosis and analysis. Most of the imported drivers have the functions of load inertia measurement and automatic gain adjustment. Some of them can automatically identify the motor parameters and automatically determine the zero position of the encoder, while others can automatically carry out vibration suppression. The combination of electronic gear, electronic cam, synchronous tracking, interpolation motion and other control functions and drive together provides a better experience for servo users.
Networking and modularization
It has become a common practice for European and American manufacturers to integrate fieldbus, industrial Ethernet technology and even wireless network technology into servo driver. The important direction of modern industrial LAN development and the focus of competition among various bus standards is how to adapt to the requirements of high-performance motion control for real-time, reliability and synchronization of data transmission. With the increasing demand for large-scale distributed control devices and the successful development of high-end CNC system, the development of networked digital servo has become an urgent task. Modularization not only refers to the combination of servo drive module, power supply module, regenerative braking module and communication module, but also refers to the modularization and reusability of software and hardware in servo driver.
From fault diagnosis to predictive maintenance
With the continuous development of machine safety standards, the traditional fault diagnosis and Protection Technology (judge the cause of the problem and take measures to avoid the expansion of the fault) has been out of date. The latest products embedded predictive maintenance technology, so that people can timely understand the dynamic trend of important technical parameters through the Internet, and take preventive measures. For example, pay attention to the increase of current, evaluate the peak current when the load changes, monitor the temperature sensor when the shell or core temperature rises, and be alert to any distortion of the current waveform.
Specialization and diversification
Although there are general servo products in the market, there are many servo systems designed and manufactured for a specific application. With the appearance of motors with different magnetic properties, different shapes, different surface bonding structures (SPM) and embedded permanent magnet (IPM) rotor structure, the application of split core structure technology in Japan makes the production of permanent magnet brushless servo motor achieve high efficiency, large batch and automation, and cause the research of domestic manufacturers.
Miniaturization and large scale
Both permanent magnet brushless servo motor and stepper motor are actively developing to smaller size, such as 20, 28, 35mm outer diameter; at the same time, we are also developing models with higher power and size, and we have seen the emergence of 500kW permanent magnet servo motor. It reflects the trend of polarization.