1.1 AC servo system.
1.1.1 Concept.
AC servo systems include AC servo systems based on asynchronous motors and AC servo systems based on synchronous motors. Servo comes from the English word servo, which refers to the system following external instructions to carry out the desired motion, including position, speed and moment. The development of servo system has gone through the process from hydraulic, pneumatic to electrical, and the electrical servo system includes servo motors, feedback devices and controllers. In the 60s of the 20th century, the first DC motor was used as the main executive component, and after the 70s, the cost performance of AC servo motor continued to improve, and gradually replaced DC motor as the dominant executive motor of the servo system. The function of the controller is to complete the closed-loop control of the servo system, including torque, speed and position, etc. What we usually call a servo drive already includes the basic functions of the controller and the power amplification part. Although open-loop servo systems with direct drive from power stepper motors were once widely used in the field of so-called economical CNC in the 90s, they were quickly replaced by AC servos. In the 21st century, the AC servo system is becoming more and more mature, the market is showing rapid diversification and development, and many brands at home and abroad have entered the market competition. AC servo technology has become one of the supporting technologies of industrial automation.
In the AC servo system, the types of motors include permanent magnet synchronous AC servo motor (PMSM) and induction asynchronous AC servo motor (IM), among them, the permanent magnet synchronous motor has very good low-speed performance, can achieve weak field and high-speed control, wide speed regulation range, high dynamic characteristics and efficiency, has become the mainstream choice of servo system. Although the asynchronous servo motor has a strong structure, simple manufacturing and low cost, there is a gap in characteristics and efficiency, and it is only valued in high-power occasions.
1.1.2 Classification.
AC servo motors can be divided into permanent magnet synchronous motors, permanent magnet brushless DC motors, induction (or asynchronous) motors and reluctance synchronous motors according to the different operating principles of the motors. These motors have the same stator structure of the three-phase windings.
Inductive AC servo motor, its rotor current is generated by the slip potential, and interacts with the magnetic field to produce torque, its main advantages are brushless, solid structure, low cost, maintenance-free, low environmental requirements, its main magnetic general excitation current generation, it is easy to achieve weak field control, high speed can reach 4 5 times the rated speed; The disadvantage is that the excitation current is required, the internal power factor is low, the efficiency is low, the rotor heat dissipation is difficult, the servo drive capacity is required, the electromagnetic relationship of the motor is complex, it is difficult to realize the control of the magnetic flux and torque of the motor, the change of the nonlinear parameters of the motor affects the control accuracy, and the parameters must be identified to achieve a better control effect.
Permanent magnet synchronous AC servo motor, the air gap magnetic field is generated by rare earth permanent magnets, and the torque control is realized by adjusting the current of the armature, and the control of torque is simpler than that of the induction motor, and can achieve high control accuracy; The rotor has no copper and iron loss, high efficiency, high internal power factor, and also has the characteristics of brushless and maintenance-free, small volume and inertia, and good rapidity; Axis position sensors are required for control in order to identify the position of the air-gap magnetic field; **More expensive than induction motors.
The structure of the brushless DC servo motor is the same as that of the permanent magnet synchronous servo motor, with the help of the signal of a simpler position sensor (such as Hall magnetosensitive switch) to control the commutation of the armature winding, and the control is the simplest; Because the commutation of each winding needs a set of power switching circuits, the number of armature windings usually only adopts three phases, which is equivalent to a DC motor with only three commutator pieces, so the pulsating torque of the motor is large during operation, resulting in the pulsation of speed, and the speed closed-loop needs to be used to run at a lower speed, and the air gap magnetic flux of the motor is a square wave distribution, which can reduce the cost caused by the electric mechanism. Sometimes, it is difficult to distinguish between brushless DC servo system and synchronous AC servo system, but in fact, the control performance of the two is quite different.
Reluctance synchronous motors, used less, slightly.
1.1.3 Performance indicators.
The performance indicators of AC servo system can be measured from the aspects of speed regulation range, positioning accuracy, speed stabilization accuracy, dynamic response and operation stability. The speed regulation range of low-grade servo system is more than 1:1000, generally 1:5000 1:10000, and high-performance can reach more than 1:100000; The positioning accuracy generally has to reach 1 pulse, and the steady speed accuracy, especially at low speeds, such as given 1rpm, is generally 0Within 1rpm, the high-performance can reach 0Within 01rpm; In terms of dynamic response, the index usually measured is the highest response frequency of the system, that is, the phase lag of the output velocity waveform of the system is not more than 90° or the amplitude is not less than 50% given the highest frequency of sinusoidal speed instructions. The response frequency of imported Mitsubishi servo motor MR J3 series is as high as 900Hz, while the frequency of domestic mainstream products is 200 500Hz. In terms of operation stability, it mainly refers to the ability of the system to maintain stable operation and ensure certain performance indicators under voltage fluctuations, load fluctuations, motor parameter changes, changes in the output characteristics of the upper controller, electromagnetic interference, and other special operating conditions. In this regard, there is a big gap between domestic products, including some Taiwanese products, and the world's advanced level.
1.1.4 Control methods.
In terms of control strategy, the voltage frequency control method and the open-loop flux trajectory control method based on the steady-state mathematical model of the motor are difficult to achieve good servo characteristics, and the vector control method based on the dynamic decoupling mathematical model of the permanent magnet motor is widely used, which is the core control method of the modern servo system. In order to further improve the control characteristics and stability, people have proposed theories such as feedback linearized control, sliding mode variable structure control, adaptive control, etc., as well as fuzzy control and neural network control methods that do not rely on mathematical models, but most of them are applied on the basis of vector control. In addition, high-performance servo control must rely on high-precision rotor position feedback, and it has been hoped that this link has been eliminated and sensorless control technology has been developed. So far, in the commercialized products, the use of no position sensor technology can only achieve a speed ratio of about 1:100, which can be used in some low-grade servo control occasions that do not require high position and speed accuracy, such as the servo control of sewing machines that simply pursue fast start-stop and braking, and the high performance of this technology still has a long way to go.
1.1.5 Development status.
B&R's (B&R) Industrial Automation CoposMulti drive system features a modular, scalable structure that provides 1 to 2 servo axes per axis module and integrates a 24VDC auxiliary power module that provides drives, controllers and peripherals with a link to the DC bus for open, short and overload protection. Other features include a modular design for cooling by air, oil or water, ensuring environmental safety through an energy regeneration system. In China, we have not seen a manufacturer carry out a similar modular design and integrate the concept of machine safety into the product.
Emerson Control Techniques exhibited UniDrive and other AC and DC actuator products. UniDrive drives cover power ranges from 055 675kw, different control software can drive asynchronous motors, permanent magnet synchronous servo motors and brushless DC motors. The rated output power is 0The 25 11kW Varmeca integrated variable speed motor and variable speed drive (VSD) are available in both closed-loop vector and distributed (Proxdrive) versions. It is worth noting that VSD systems (ATEX) are suitable for operation in potentially explosive gases. Whereas, the rated output power is 0The 55 400 kW FLSD driver is said to be able to operate in Class B or Zone C Class 1 Class 2 gases. Correspondingly, the product power range of domestic servo drive manufacturers is mostly below 10kw, and there is no special protection level of commercial products, which is a big gap at home and abroad, and it is also the direction of differentiated competition of domestic servo manufacturers in the future.
Rockwell Automation exhibited PowerFlex drive technology. PowerFlex's roadmap shows that the Public Industrial Protocol (CIP) Motion Application Protocol, which will appear in 2006-07, is expected to seamlessly synchronize multi-axis servo and variable frequency drives running in the same system. In terms of industrial protocols suitable for motion control, we also see Beckhoff's EtherCAT, B&R's PowerLink, SynqNet developed by Mei under Danaher, Profinet from Siemens, and the prestigious Sercos that have evolved to Sercos. These communication protocols offer the possibility of real-time synchronous control of multiple axes and are also integrated into some high-end servo drives. In China, even low-end buses such as CAN have not become the standard configuration of servo drives, and commercial drives using high-performance real-time fieldbuses have not yet appeared. On the one hand, this is because the basic performance of our servos has not yet reached the corresponding level, and on the other hand, it is also because the market has not yet developed to this extent. Fortunately, we have seen that some units have carried out beneficial R&D practices, on the one hand, digesting foreign advanced technology, and on the other hand, trying to launch their own bus standards. Hollysys Motor expects to integrate a variety of optional communication modules in its next-generation servo products, including CAN, USB, Fireware and Sercos, as well as CANSMC (bus for multi-axis synchronous motion control) jointly developed by Hollysys Motor and Beihang Airlines, and Bluetooth wireless communication based modules are also under development. Individual units such as the Shenyang High-end CNC R&D Center of the Chinese Academy of Sciences have also developed their own motion control bus protocols.
Schneider Electric's Lexium 05 servo controller has the same form factor as a VFD inverter and is aimed at low-cost applications. In fact, using the mass production capacity of the inverter to launch low-end servos has become a means of competition for some manufacturers. The company's Berger Lahr brand can be seen everywhere at its stand. Its intelligent, integrated motor and controller products (ICLAs) are available in three motor versions: stepper motors, AC servo motors, and three-phase brushless DC motors. ICLA (acronym for "Integrated, Closed-Loop, Actuator") combines motor, position control, power electronics and feedback in a compact unit. This idea of integrated design is also evident in companies such as Animatics in the United States, and similar products are available from AMK in Germany. This is a true mechatronic product that presents designers with a range of engineering challenges, including electromagnetic compatibility, thermal control, component miniaturization, special structural design, and more. In China, there is no manufacturer to launch products with independent intellectual property rights.
High-performance servo motors with integrated planetary gear train from Baumüller with up to 98% efficiency and low noise; Direct drive high-torque servo motor with output of 13500Nm in the range of 100 300 rpm. In China, we see that Hollysys Motor Company provides similar products with integrated planetary gear reducers in its Dolphin series of low-voltage brushless servo motor series, and Shenzhen Stepper also claims to be able to provide step-to-step servo motors with reducers. In the direct drive torque motor market, Chengdu Precision Motor Factory can provide customized motor components, but the customer needs to install additional feedback devices and third-party drives.
Yaskawa Electric Europe (YEE) showcased its popular universal Sigma-type servo motors. Other developments in YEE include a power rating of 05 5kw explosion-proof and ATEX compliant AC servo motor. Another development from Yaskawa is a high-power servo motor with an output of up to 500 kW. The commercialization of the project is expected to be completed in 2007. From this, we can see the trend of international manufacturers to specialize and develop large-scale servos.
1.2 Siemens AC servo system.
SINAMICS is the core drive product of Siemens, which can be combined with different SIMATIC controllers to achieve motion control in different scenarios. According to different application scenarios, motion control systems can be divided into basic motion control, mid-range motion control and high-end motion control. Among them, the basic motion control mainly uses SIMATIC S7-200 Smart PLC or SIMATIC S7-1200 PLC pulse train, RS485 communication or PROFINET communication to connect to SINAMICS drive for speed regulation and positioning. The mid-range motion control mainly uses SIMATIC S7-1500 PLC to connect to the SIMAMICS drive through Profinet communication for speed regulation, positioning and relative synchronization control. High-end motion control mainly uses SIMATIC S7-1500T or SIMOTION controllers to connect to SINAMICS drives via Profinet communication for speed regulation, positioning, relative synchronization, absolute synchronization, cam synchronization and motion control.
The SINAMICS drive includes SINAMICS inverter and SINAMICS servo drive, where SINAMICS servo drive products include SINAMICS V90 servo drive, SinamiCs S210 servo drive and S120 servo drive.
The SINAMICS V90 servo drive is a single-axis AC servo drive product, which needs to be used in conjunction with the SIMOTICS 1FL6 servo motor to form the entire servo system, which is widely used in various industries.
The SinamiCs S210 servo drive is also a single-axis AC servo product (available in single-phase and three-phase powered servo drives) and needs to be used in conjunction with a 1FK2 motor (available in both compact and highly dynamic servo versions). Designed for highly dynamic, high-performance sports scenarios.
The SIMOTICS S120 servo drives are available in single-axis and common-DC bus multi-axis products for use with the SIMOTICS 1FK7 or 1FT7 series to meet high-performance multi-axis requirements, while supporting DCC programming within the servo for quick implementation of user-specific drive solutions.
The Sinamics product family.
1.3 Siemens small servo system.
The SINAMICS V90 servo drive system is Siemens' small servo drive system for basic applications, consisting of a SINAMICS V90 servo drive, a SIMOTICS 1FL6 servo motor and a Motion-Connect 300 connection cable in the power range of 005~7kw。
According to the different control methods of the servo drive, the SINAMICS V90 servo drive can be divided into pulse type (PTI integrates pulse train input, analog, RS485 communication) and bus type (PN), and according to the different power supply levels of the drive, it can be divided into AC 220V (including single-phase AC 220V and three-phase AC 220V) and three-phase AC 400V
200-240v
400v
PTI version.
pn version. 
List of total drivers.
According to the different inertia of servo motors, SIMOTICS 1FL6 servo motors can be divided into low inertia servo motors and high inertia servo motors, and according to the different types of motor encoders, they can be divided into incremental encoders and absolute encoders; According to whether there is a brake or not, it can be divided into two servo motors: with and without brake; According to whether there is a key or not, it can be divided into servo with key and without key.
High inertia 1fl6
Low inertia 1fl6
According to the different functions of the connecting cables, the motion-connect 300 connecting cables are divided into motor power cables, motor encoder cables and motor brake cables; According to different encoders, it can be divided into incremental encoder cable and absolute encoder cable; According to the different inertia, it can be divided into low inertia servo connection cable and high inertia servo connection cable, which can also be distinguished from the shape.
For the SIMOTICS 1FL6 low-inertia servo motor with a shaft height of 50, the Motion-Connect 300 is a metal head and a non-plastic head. It is important to note that the motion-connect 300 connection cable is a fixed-length non-flexible cable, which can be purchased for flexible connection or e-chain® use, and the user can customize the connection cable by himself.
In addition, the components of the SINAMICS V90 servo drive system are not allowed to be combined arbitrarily, usually the SIMOTICS 1FL6 low inertia motor is connected to the SIMOTICS 1FL6 low inertia motor via the MITION-CONNECT 300 low inertia servo motor connection cable; The SIMOTICS V90 AC 400V servo drive is connected to the SIMOTICS 1FL6 high inertia motor via the MITION-CONNECT 300 high inertia servo motor connection cable;
SINAMICS V90 servo drive system can be widely used in electronic assembly, printing industry, packaging industry, metal forming industry, etc.
1.4 Selection steps.
a Simotics 1FL6 servo motor selected.
b Select SINAMICS V90 servo drive.
c Select Motion-Connect 300 to connect the system.
d Select the SIMATIC PLC controller.
Selection steps. end
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