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This chapter we will talk about the birth, development and evolution of stepper motor, mainly talk about what is stepper motor.
1.1 The development history of stepper motor
Motors are essential to industrial development and play an important role in it. The application of motor is expanding more not only in power application but also in the use of control area. With the increasing importance of controlling motors, the number of the use of control motors is also increasing year by year. Stepper motor is a type of control motor that can get on speed control and positioning control without using a feedback loop, which is the so-called open-loop motor control. Its application mainly focuses on OA (Office Automation) machines and FA (Factory Automation) machines that solve strong office services, and is widely used in medical machinery, measuring instruments, cars, and game machines. In terms of quantity, the OA machine application accounts for about 75% of the use of total number of stepper motors.
Although stepper motor has been used in a large numbers recently, its principle has long existed. Stepper motors were developed during the same period along with electromagnets and plunger pumps. French Froman put forward a method of converting the attractive force of an electromagnet into a rotating torque. At that time, the switching of the excitation phase was accomplished using the contact points of a mechanical cam, it is the prototype of a stepper motor. There is also a rotating coil application method now. In 1920, the actual application of stepper motors began, so called VR (Variable Reluctance) type stepper motors, used by the British Navy as positioning control and remote control.
The generation of hybrid stepper motors(combination of VR and PM), which was about in 1952, evolved from the generators developed by Karl Feiertag, GE company of the United States. Its structure is the same as current two phase stepper motor and obtains the US patent. Originally it is used as a low-speed synchronous motor. After that, Superior Electric and Sigma Instruments companies in United States developed HB type stepping motors with two-phase 1.8-degree step angles. At that time, regarding of the small current, high inductance, and constant voltage drive, the commutation pulse was only 300pps (now is 10-20kpps).
On the other hand, from the aspect of the drive circuit, the development of stepper motor is closely related to the development of the transistor semiconductor device. In 1950 diode semiconductor came out, and then MOS semiconductor in 1964. IC (integrated circuit) appeared in 1965, and LSI was practically used in 1967. In particular, after the high development of semiconductor materials from 1950 to 1965, it entered into 1970s. Because of the low cost and high reliability of logic digital circuits, application of stepper motors have been increasing dramatically.
Oshima, from Tokyo University in Japan, published a paper about VR type stepper motors at the Automatic Control Annual Meeting in 1958 . International Society of Stepper Motors was founded in 1970 and held its first IMCSD（Incremental Motion Control Systems and Devices) at Illinois University in the United States. The conference was hosted by Professor BC Kuo from Illinois University. The two companies Warner Electric and Westool co-organized the conference. About two-thirds of the published papers originated from the corporate field, and the remaining one-third come from universities. Many of the papers published by IMCSD are related to stepper motors, from which one can learn about the latest technologies and research trends of stepper motors. American learners and business technicians make a wide research about stepper motors.
Stepper motors have had a large scale application in various industries from 1977, like medical, CNC, robotics and 3D printer, etc. Two-phase stepper motors (Figure 1.1) were used to drive the FDD (floppy disk drive) output shafts.