Since the Indramat division of MANNESMANN’s Rexroth company officially launched the MAC permanent magnet AC servo motor and drive system at the Hanover Trade Fair in 1978, this marked the entry of this new generation of AC servo technology into the practical stage. By the mid-1980s, all companies had complete product lines. The entire servo system market shifted to AC systems. The early analog systems had deficiencies in aspects such as zero drift, anti-interference, reliability, accuracy, and flexibility, and could not fully meet the requirements of motion control. In recent years, with the application of microprocessors and new digital signal processors (DSPs), digital control systems have emerged, with the control part being fully carried out by software, known as DC servo systems or three-phase permanent magnet AC servo systems.
Most high-performance electric servo systems adopt permanent magnet synchronous AC servo motors, and the control drivers mostly use fast and precisely positioned full digital position servo systems. Typical manufacturers include German Siemens, American Coromagnon, Japanese Panasonic and ABB, etc.
The small AC servo motor and driver produced by Yaskawa Electric Corporation of Japan, among others, include the D series suitable for CNC machines (with a maximum rotational speed of 1000 r/min and a torque of 0.25 to 2.8 N.m), and the R series suitable for robots (with a maximum rotational speed of 3000 r/min and a torque of 0.016 to 0.16 N.m). Later, six series including M, F, S, H, C, and G were also introduced. In the 1990s, new D series and R series were launched. The old series’ rectangular wave drive and 8051 single-chip microcontroller control were changed to sine wave drive, controlled by 80C, 154 CPUs and gate array chips, with torque fluctuation reduced from 24% to 7% and reliability improved. Thus, within a few years, an eight-series system (power range from 0.05 to 6 kW) was formed, meeting the different needs of various machinery, handling mechanisms, welding robots, assembly robots, electronic components, processing machinery, printing machines, high-speed winding machines, and winding machines.
The Japanese Fanuc (Fanuc) company, renowned for producing CNC machine tools, also launched the S series (13 specifications) and L series (5 specifications) of permanent magnet AC servo motors in the mid-1980s. The L series has a smaller rotational inertia and mechanical time constant, suitable for position servo systems requiring particularly rapid response.
Other Japanese manufacturers, such as Mitsubishi Motors (HC-KFS, HC-MFS, HC-SFS, HC-RFS, and HC-UFS series), Toshiba Machinery (SM series), Tama Iron Works (BL series), Sanyo Electric (BL series), and Rikkyo Motors (S series), among many others, have also entered the competition for permanent magnet AC servo systems.
The MAC series AC servo motors of the Indramat division of Rexroth in Germany have 7 base sizes and 92 specifications.
The IFT5 series of three-phase permanent magnet AC servo motors of Siemens are divided into standard and short types, with a total of 8 base sizes and 98 specifications. It is claimed that this series of AC servo motors is only half the weight of the DC servo motors IHU series with the same output torque, and the accompanying transistor pulse width modulation driver 6SC61 series can control up to 6 axes of motor.
The German Bosch (BOSCH) company produces SD series (17 specifications) and SE series (8 specifications) AC servo motors with ferrite permanent magnets and Servodyn SM series drive controllers. The renowned American servo equipment manufacturing company Gettys, which was once a division of Gould Electronics (Motion Control Division), produced the M600 series AC servo motors and the A600 series servo drives. Later, it merged into AEG and restored the Gettys name, launching the A700 fully digital AC servo system.
The drive division of A-B (ALLEN-BRADLEY) Company produced the 1326 type ferrite permanent magnet AC servo motors and the 1391 type AC PWM servo controllers. The motors included 30 specifications with 3 different base sizes.
I.D. (Industrial Drives) is the industrial drive division of the famous Kollmorgen in the United States. It once produced three series of 41 specifications of brushless servo motors and the BDS3 type servo driver. Since 1989, it has launched a new series of permanent magnet AC servo motors [3], including three types: B (low inertia), M (medium inertia), and EB (explosion-proof), with 5 base sizes (10, 20, 40, 60, 80) and 42 specifications each. All use neodymium iron boron permanent magnetic materials, with a torque range of 0.84 to 111.2 N.m and a power range of 0.54 to 15.7 kW. The accompanying drivers include the BDS4 (analog type), BDS5 (digital type, including position control) and Smart Drive (digital type), with a maximum continuous current of 55 A. The Goldline series represents the latest level of permanent magnet AC servo technology.
Inland, originally a division of Kollmorgen abroad, has now merged into AEG and is known for producing DC servo motors, DC torque motors and servo amplifiers. It produces 17 specifications of SmCo permanent magnet AC servo motors with three base sizes (BHT1100, 2200, 3300) and eight controllers.
The French Alsthom Group produces the LC series (long type) and GC series (short type) AC servo motors with 14 specifications at its Parvex factory in Paris, and also produces the AXODYN series of drivers.
The former Soviet Union developed two series of AC servo motors for CNC machine tools and robot servo control. The 2ДBy series uses ferrite permanent magnet and has two base sizes, each with three core lengths and two winding data, totaling 12 specifications, with a continuous torque range of 7 to 35 N.m. The 2ДBy series uses rare earth permanent magnet and has 6 base sizes and 17 specifications, with a torque range of 0.1 to 170 N.m, and is paired with the 3ДБ type controller.
In recent years, the Japanese Panasonic Company has launched the fully digital MINAS series of AC servo systems. The permanent magnet AC servo motors in this series include the small inertia MSMA series with power ranging from 0.03 to 5 kW, totaling 18 specifications; the medium inertia series includes three series: MDMA, MGMA, and MFMA, with power ranging from 0.75 to 4.5 kW, totaling 23 specifications; and the large inertia MHMA series has a power range of 0.5 to 5 kW, with 7 specifications.
In recent years, Samsung of South Korea has developed fully digital permanent magnet AC servo motors and drive systems. The FAGA series of AC servo motors includes multiple models such as CSM, CSMG, CSMZ, CSMD, CSMF, CSMS, CSMH, CSMN, and CSMX, with power ranging from 15 W to 5 kW. Nowadays, the (Powerrate) comprehensive index is commonly used as the quality factor of servo motors to evaluate the dynamic response performance of various AC and DC servo motors and stepper motors. The power change rate represents the ratio of the continuous (rated) torque of the motor to the rotor’s rotational inertia.
Through calculation and analysis based on the power change rate, it can be known that the technical indicators of permanent magnet AC servo motors are the best among those from the Goldline series of I.D. in the United States, followed by the IFT5 series from Siemens in Germany.