Paper on motor control technology 1
Stepping motor control system
Abstract: As an executive component, stepping motor is one of the key products of mechatronics, which is widely used in various automatic control systems. With the development of microelectronics and computer technology, the demand of stepping motor is increasing day by day, and it has been applied in various fields of national economy.
Keywords: stepping motor; Elements of implementation; Computer; develop
Principle and characteristics of 1 stepping motor
1. 1 development status of stepping motors
Stepper motor is an open-loop control element, which converts electric pulse signal into angular displacement or linear displacement. When the stepping driver receives a pulse signal, it drives the stepping motor to rotate by a fixed angle in the set direction (called? Step angle? ), its rotation runs step by step at a fixed angle. The angular displacement can be controlled by controlling the number of pulses, so as to achieve the purpose of accurate positioning; At the same time, the speed and acceleration of motor rotation can be controlled by controlling the pulse frequency, so as to achieve the purpose of speed regulation. In the case of non-overload, the rotation speed and stop position of the motor only depend on the frequency and number of pulses of the pulse signal, which is not affected by the load change, that is, the motor turns a step angle by adding a pulse signal. The existence of this linear relationship, plus the characteristics of stepping motor, such as only periodic error and no accumulated error. In the field of speed and position control, it is very simple to use stepping motor to control. Stepper motor can be used as a special motor for control, and it is widely used in all kinds of open-loop control because it has no accumulated error (accuracy is 100%).
1.2 characteristics of stepping motor
1. When the stepping motor works, the windings of each phase are not energized continuously, but are energized in turn according to certain rules. 2. The angle at which the rotor rotates every time the pulse electric signal is input is called the step angle. 3. The stepper motor can control the angle or speed according to specific instructions. In angle control, every time a pulse is input, the stator winding is switched once, the output shaft rotates by an angle, the number of steps is consistent with the number of pulses, and the angular displacement of the output shaft is proportional to the input pulse. In speed control, continuous pulses are fed into the windings of the stepping motor, and each phase winding is continuously energized in turn, and the stepping motor rotates continuously, and its rotation speed is proportional to the pulse frequency. Changing the energization sequence, that is, changing the rotating direction of the stator magnetic field, can control the motor to rotate forward or backward.
Some typical applications of 1.3 stepping motor
① Stepping motors are mainly used in some occasions with positioning requirements. For example: wire cutting table, wool planting machine table (hole positioning), packaging machine table (fixed length). Basically, it is used in situations involving positioning.
② Widely used in ATM machines, inkjet printers, engraving machines, photo printers, spraying equipment, medical instruments and equipment, computer peripherals and mass storage equipment, precision instruments, industrial control systems, office automation, robots and other fields. It is especially suitable for applications requiring stable operation, low noise, fast response, long service life and large output torque.
③ Stepping motors are widely used in computerized embroidery machines and other textile machinery and equipment. This kind of stepping motor is characterized by small torque, fast response speed when starting frequently, low running noise, stable operation, good control performance and low comprehensive cost.
At present, the stepper motors used in computerized embroidery machine are mostly three-phase hybrid stepper motors. The application of subdivision drive technology can greatly improve the running quality of stepper motors, reduce torque fluctuation, suppress oscillation, reduce noise and improve step resolution.
1.4 working principle and structure of stepping motor
Stepping motor is an executive mechanism that converts electric pulse into angular displacement. Generally speaking, the stepping driver receives a pulse signal and drives the stepping motor to rotate by a fixed angle (and stepping angle) in the set direction. The angular displacement can be controlled by controlling the number of pulses, so as to achieve the purpose of accurate positioning; You can also control the speed and acceleration of motor rotation by controlling the pulse frequency, so as to achieve the purpose of speed regulation.
In the case of non-overload, the rotation speed and stop position of the motor only depend on the frequency and number of pulses of the pulse signal, which is not affected by the load change, that is, the motor turns a step angle by adding a pulse signal. The existence of this linear relationship, plus the characteristics of stepping motor, such as only periodic error and no accumulated error.
1.5 rotation
If phase A is energized and phase B and phase C are de-energized, the tooth 1 is aligned with phase A due to the magnetic field (the rotor is not subjected to any force, and the same applies below). If phase B is energized and phases A and C are de-energized, tooth 2 should be aligned with B.. At this time, the rotor moves to the right through 1/3て. At this time, teeth 3 and C are offset by 1/3て, and teeth 4 and A are offset (て- 1/3 て). If phase C is energized, phase A and phase B are not. At this time, the rotor moves to the right 1/3て, and the offset between teeth 4 and A is 1/3て. If phase A is energized, phase B and phase C are de-energized, and teeth 4 are aligned with A, the rotor moves to the right through 1/3て.
Thus, when A, B, C and A are energized respectively, the tooth 4 (i.e. the tooth before tooth 1) moves to phase A, and the motor rotor rotates to the right by one pitch. If power is continuously supplied by pressing A, B, C and A, the motor will rotate to the right at every step (every pulse) of1/3. If power is supplied by pressing A, C, B and A, the motor will reverse. Through the conduction times (pulse number) and frequency, we can see that the position and speed of the motor are in one-to-one correspondence. And the direction is determined by the conduction order.
2 circuit design analysis
2. 1 8253 and 8255 drive stepping motor circuits
① Connect the circuit according to the diagram and use 8255 to output the pulse sequence. Switches K0 ~ K6 control the rotating speed of the stepping motor, and K7 controls the steering of the stepping motor. 8255 CS is connected to 288H~28FH. PA0~PA3 is connected with BA ~ BD; PC0~PC7 are connected with K0 ~ K7.
② Programming: When one switch in K0 ~ K6 is? 1? When the stepping motor is turned up, the speed of the motor is different. K7。 Press the motor to rotate forward, press the motor to rotate backward.
2.2 Calculation of important experimental parameters
According to the actual test, when the number of steps is set to about 59. The stepping motor rotates once.
According to the experimental requirements: first clockwise, 6 times per minute, turn for ten minutes. The approximate number of steps is 59 * 6 * 10 = 3540.
Stop for three seconds: 8086 instructions with machine cycle of1/5mhz.3s =1/5mhz *15 * exp6, namely 15M machine cycles.
Turn counterclockwise, 30 times per minute, and turn for ten minutes. The approximate number of steps is 59 * 30 * 10 = 17700.
2.3 Practical Problems and Solutions
(1) The hardware connection and software programming are not skilled enough. Through various materials and reading books, the design scheme and specific design contents of hardware and software are determined.
② The keyboard and LED display control are not ideal. After careful interpretation of the program, the design purpose was finally achieved. Press the key 10 to display 0. . . 0030, press 12 to display 1. . . 0006, press 14 to start operation, and press 15 to stop operation. (3) Speed control was not accurate enough at first. After repeated tests, it was finally determined to be 59 steps per lap. Calculate the set step size of 6R/MIN and 30R/MIN.
3 sum up experience
Firstly, the integrated environment software of Star Research is used to edit the running program, and the experimental results are debugged on the STAR ES598PCI experimental instrument, and the experimental program and hardware circuit are analyzed. Then, when the original source program is used for experiments, the speed control of the motor is not obvious, so it is necessary to modify the values of the control step Takesetpcount and the frequency division number 8253 to make the motor speed reach 6r/min and 30r/min. Secondly, adjust the 8259 control keyboard and display, and finally realize the real-time display of speed and direction, and use the keyboard to control its start and stop. Because the operation of stepping motor is controlled by electric pulse signal, the angular displacement or linear displacement of stepping motor is proportional to the number of pulses. Given each pulse, stepping motor rotates by an angle (step angle) or moves forward/backward one step, so I hope to see this characteristic of the motor clearly. By setting the pace and speed, we can observe the stepping of the motor and the number of steps in one rotation.
refer to
1 Wang Zhongmin, etc. Principles of Microcomputer (2nd Edition). Xi An: xidian university Publishing House, 2007.
2 Jiang, Dong Xiufeng. Analog Electronic Technology (3rd Edition). Xi An: xidian university Publishing House, 2009.
Li Sanren. Principle and interface technology of single chip microcomputer. Beijing: Higher Education Press, 20 10.
Stepping motor control system
Han Hao
(Department of Physics and Electromechanical Engineering, Xi 'an University of Arts and Sciences, Shaanxi xi 7 10000)
Abstract: As an executive component, stepping motor is one of the key products of mechatronics, which is widely used in various automatic control systems. With the development of microelectronics and computer technology, the demand of stepping motor is increasing day by day, and it has been applied in various fields of national economy.
Keywords: stepping motor; Elements of implementation; Computer; develop
Principle and characteristics of 1 stepping motor
1. 1 development status of stepping motors
Stepper motor is an open-loop control element, which converts electric pulse signal into angular displacement or linear displacement. When the stepping driver receives a pulse signal, it drives the stepping motor to rotate by a fixed angle in the set direction (called? Step angle? ), its rotation runs step by step at a fixed angle. The angular displacement can be controlled by controlling the number of pulses, so as to achieve the purpose of accurate positioning; At the same time, the speed and acceleration of motor rotation can be controlled by controlling the pulse frequency, so as to achieve the purpose of speed regulation. In the case of non-overload, the rotation speed and stop position of the motor only depend on the frequency and number of pulses of the pulse signal, which is not affected by the load change, that is, the motor turns a step angle by adding a pulse signal. The existence of this linear relationship, plus the characteristics of stepping motor, such as only periodic error and no accumulated error. In the field of speed and position control, it is very simple to use stepping motor to control. Stepper motor can be used as a special motor for control, and it is widely used in all kinds of open-loop control because it has no accumulated error (accuracy is 100%).
1.2 characteristics of stepping motor
1. When the stepping motor works, the windings of each phase are not energized continuously, but are energized in turn according to certain rules. 2. The angle at which the rotor rotates every time the pulse electric signal is input is called the step angle. 3. The stepper motor can control the angle or speed according to specific instructions. In angle control, every time a pulse is input, the stator winding is switched once, the output shaft rotates by an angle, the number of steps is consistent with the number of pulses, and the angular displacement of the output shaft is proportional to the input pulse. In speed control, continuous pulses are fed into the windings of the stepping motor, and each phase winding is continuously energized in turn, and the stepping motor rotates continuously, and its rotation speed is proportional to the pulse frequency. Changing the energization sequence, that is, changing the rotating direction of the stator magnetic field, can control the motor to rotate forward or backward.
Some typical applications of 1.3 stepping motor
① Stepping motors are mainly used in some occasions with positioning requirements. For example: wire cutting table, wool planting machine table (hole positioning), packaging machine table (fixed length). Basically, it is used in situations involving positioning.
② Widely used in ATM machines, inkjet printers, engraving machines, photo printers, spraying equipment, medical instruments and equipment, computer peripherals and mass storage equipment, precision instruments, industrial control systems, office automation, robots and other fields. It is especially suitable for applications requiring stable operation, low noise, fast response, long service life and large output torque.
③ Stepping motors are widely used in computerized embroidery machines and other textile machinery and equipment. This kind of stepping motor is characterized by small torque, fast response speed when starting frequently, low running noise, stable operation, good control performance and low comprehensive cost.
At present, the stepper motors used in computerized embroidery machine are mostly three-phase hybrid stepper motors. The application of subdivision drive technology can greatly improve the running quality of stepper motors, reduce torque fluctuation, suppress oscillation, reduce noise and improve step resolution.
1.4 working principle and structure of stepping motor
Stepping motor is an executive mechanism that converts electric pulse into angular displacement. Generally speaking, the stepping driver receives a pulse signal and drives the stepping motor to rotate by a fixed angle (and stepping angle) in the set direction. The angular displacement can be controlled by controlling the number of pulses, so as to achieve the purpose of accurate positioning; You can also control the speed and acceleration of motor rotation by controlling the pulse frequency, so as to achieve the purpose of speed regulation.
In the case of non-overload, the rotation speed and stop position of the motor only depend on the frequency and number of pulses of the pulse signal, which is not affected by the load change, that is, the motor turns a step angle by adding a pulse signal. The existence of this linear relationship, plus the characteristics of stepping motor, such as only periodic error and no accumulated error.
1.5 rotation
If phase A is energized and phase B and phase C are de-energized, the tooth 1 is aligned with phase A due to the magnetic field (the rotor is not subjected to any force, and the same applies below). If phase B is energized and phases A and C are de-energized, tooth 2 should be aligned with B.. At this time, the rotor moves to the right through 1/3て. At this time, teeth 3 and C are offset by 1/3て, and teeth 4 and A are offset (て- 1/3 て). If phase C is energized, phase A and phase B are not. At this time, the rotor moves to the right 1/3て, and the offset between teeth 4 and A is 1/3て. If phase A is energized, phase B and phase C are de-energized, and teeth 4 are aligned with A, the rotor moves to the right through 1/3て.
Thus, when A, B, C and A are energized respectively, the tooth 4 (i.e. the tooth before tooth 1) moves to phase A, and the motor rotor rotates to the right by one pitch. If power is continuously supplied by pressing A, B, C and A, the motor will rotate to the right at every step (every pulse) of1/3. If power is supplied by pressing A, C, B and A, the motor will reverse. Through the conduction times (pulse number) and frequency, we can see that the position and speed of the motor are in one-to-one correspondence. And the direction is determined by the conduction order. 2 circuit design analysis
2. 1 8253 and 8255 drive stepping motor circuits
① Connect the circuit according to the diagram and use 8255 to output the pulse sequence. Switches K0 ~ K6 control the rotating speed of the stepping motor, and K7 controls the steering of the stepping motor. 8255 CS is connected to 288H~28FH. PA0~PA3 is connected with BA ~ BD; PC0~PC7 are connected with K0 ~ K7.
② Programming: When one switch in K0 ~ K6 is? 1? When the stepping motor is turned up, the speed of the motor is different. K7。 Press the motor to rotate forward, press the motor to rotate backward.
2.2 Calculation of important experimental parameters
According to the actual test, when the number of steps is set to about 59. The stepping motor rotates once.
According to the experimental requirements: first clockwise, 6 times per minute, turn for ten minutes. The approximate number of steps is 59 * 6 * 10 = 3540.
Stop for three seconds: 8086 instructions with machine cycle of1/5mhz.3s =1/5mhz *15 * exp6, namely 15M machine cycles.
Turn counterclockwise, 30 times per minute, and turn for ten minutes. The approximate number of steps is 59 * 30 * 10 = 17700.
2.3 Practical Problems and Solutions
(1) The hardware connection and software programming are not skilled enough. Through various materials and reading books, the design scheme and specific design contents of hardware and software are determined.
② The keyboard and LED display control are not ideal. After careful interpretation of the program, the design purpose was finally achieved. Press the key 10 to display 0. . . 0030, press 12 to display 1. . . 0006, press 14 to start operation, and press 15 to stop operation.
(3) Speed control was not accurate enough at first. After repeated tests, it was finally determined to be 59 steps per lap. Calculate the set step size of 6R/MIN and 30R/MIN.
3 sum up experience
Firstly, the integrated environment software of Star Research is used to edit the running program, and the experimental results are debugged on the STAR ES598PCI experimental instrument, and the experimental program and hardware circuit are analyzed. Then, when the original source program is used for experiments, the speed control of the motor is not obvious, so it is necessary to modify the values of the control step Takesetpcount and the frequency division number 8253 to make the motor speed reach 6r/min and 30r/min. Secondly, adjust the 8259 control keyboard and display, and finally realize the real-time display of speed and direction, and use the keyboard to control its start and stop. Because the operation of stepping motor is controlled by electric pulse signal, the angular displacement or linear displacement of stepping motor is proportional to the number of pulses. Given each pulse, stepping motor rotates by an angle (step angle) or moves forward/backward one step, so I hope to see this characteristic of the motor clearly. By setting the pace and speed, we can observe the stepping of the motor and the number of steps in one rotation.
refer to
1 Wang Zhongmin, etc. Principles of Microcomputer (2nd Edition). Xi An: xidian university Publishing House, 2007.
2 Jiang, Dong Xiufeng. Analog Electronic Technology (3rd Edition). Xi An: xidian university Publishing House, 2009.
Li Sanren. Principle and interface technology of single chip microcomputer. Beijing: Higher Education Press, 20 10.
Motor control technology paper II
Acceleration and deceleration control of stepping motor
Abstract: The stepping motor and its working principle are analyzed in detail, and the digital control system of stepping motor based on MCS-5 1 series single chip microcomputer is designed. Stepping motor subdivision technology and constant frequency pulse width modulation technology are added in the design. Combined with the use of pulse distributor, a simple subdivision drive control circuit is developed.
[Keywords:] stepping motor; Single chip microcomputer; Segmented control
China Library ClassificationNo.: F 140 Document ID: A DocumentNo.:1009-914x (2015) 40-0038-01.
I. Introduction
With the development of science and technology and the application of microelectronic control technology, stepping motor, as a motor that can be controlled accurately, is widely used in high-tech fields such as high-precision machining machine tools, micro-robot control, space satellites and so on.
Second, the principle of stepping motor
Stepper motor is a special control motor. It can't run directly by inputting AC or DC current like a traditional motor, but needs to input pulse current to control the rotation of the motor, so the stepping motor is also called pulse motor. Its function is to convert the pulse electrical signal into corresponding angular displacement or linear displacement, that is, to give a pulse electrical signal, the motor will rotate an angle or move forward. According to the excitation mode, it can be divided into reactive type, permanent magnet type and hybrid type. In this design, reactive stepping motor is selected, and its structure is shown in figure 1.
This is a typical structure of four-phase reactive stepping motor. * * * There are four groups of stator control windings. A set of windings wound on two completely opposite magnetic poles is a phase, that is, two opposite big teeth on the stator are a phase. If the motor continuously turns on and off the control winding according to the sequence of A-B-C-D-A, the rotor will continuously rotate step by step. Its rotating speed depends on the on-off frequency of each control winding, that is, the input pulse frequency. The direction of rotation depends on the sequence in which each control winding is energized in turn.
Third, the driving control of stepping motor
Stepping motor cannot be directly connected to DC or AC power supply, so a dedicated stepping motor drive controller must be used. Stepping motor and stepping motor driver constitute the stepping motor drive system. The performance of stepping motor drive system depends not only on the performance of stepping motor itself, but also on the quality of stepping motor driver.
There are many driving modes of stepping motor, including single voltage driving, double voltage driving, chopping driving, subdivision driving, integrated circuit driving and bipolar driving. This design adopts constant frequency pulse width modulation subdivision drive control mode, which is a further improvement on the basis of chopping constant current drive, which can not only make the subdivision step angle uniform, but also avoid complicated calculation.
Fourthly, the design of constant frequency pulse width modulation subdivision circuit
1 to realize pulse distribution.
In the single chip microcomputer control of stepping motor, the control signal is generated by the single chip microcomputer. Its power-on commutation sequence is strictly in accordance with the working mode of stepping motor. Usually, we call the process of power-on commutation pulse distribution as. In this design, 87 13 pulse distributor chip is selected to control commutation.
2. Design of system control circuit.
The main circuit design of the stepping motor control system is shown in Figure 2.
As can be seen from the above figure, pins 5, 6 and 7 of the 87 13 pulse distributor are all connected to high level, so this is a control circuit for controlling the four-phase eight-beat operation of the four-phase stepping motor. Ports P 1.0 and P 1. 1 of 875 1 single chip microcomputer are respectively connected with pins 3 and 4 of 87 13 pulse distributor. The stepping pulse is provided by the P 1.0 terminal of 875 1 single chip microcomputer, and the P 1 terminal controls the steering of the stepping motor, outputs high level, and the stepping motor transmits forward; The output level is low, and the stepping motor is reversed. Single chip microcomputer is still the main body of control. It outputs 20kHz square wave through timer T0 and sends it to D flip-flop as a constant frequency signal. At the same time, the square wave pulse signal output from the pulse output end of 87 13 pulse distributor is used as the control signal, and every change of its square wave voltage makes the rotor rotate by one step.
When the square wave pulse signal Ua output from the pulse output terminal of the 87 13 pulse distributor remains unchanged, the rising edge of the constant frequency signal CLK makes the D flip-flop output Ub high, which makes the switch tubes T 1 and T2 conductive, the current in the winding rises, and the voltage drop across the sampling resistor R2 increases. When the voltage drop is greater than Ua, the comparator outputs a low level, which makes the D flip-flop output Ub low, T 1 and T2 turn off, and the winding current drops. This makes the voltage drop on R2 less than Ua, the comparator outputs a high level, the D flip-flop outputs a high level, and T 1 and T2 are turned on, so that the current in the winding rises again. This process is repeated, making the peak of winding current zigzag. Because the frequency of CLK is very high, the sawtooth wave will be very small.
When Ua suddenly rises, the voltage drop on the sampling resistor is less than Ua, the current rises for a long time, and the current amplitude rises by one level, but only one step up because the output here is a square wave signal instead of a ladder signal. What does this mean? Step signal? It only contains one step, and each step is not subdivided into many steps, but the gradient of the rising and falling of the output pulse signal is increased, so that the original square wave output becomes smooth and the control signal is smooth like a trapezoid, as shown in Figure 3.
Similarly, when Ua suddenly drops, the voltage drop on the sampling resistor is longer than Ua, the comparator output is low, and the rising edge of CLK will immediately clear the D flip-flop output 1. The power supply is always cut off, which greatly reduces the current amplitude to a new stage.
Repeat the above process. Every change of Ua will make the rotor rotate by a subdivision step.
One of the most outstanding characteristics of this circuit is that the pulse signal output by 87 13 pulse distributor replaces the ladder control signal provided by D/A converter in typical constant frequency pulse width subdivision circuit. This design greatly simplifies the circuit and reduces the control difficulty of pulse distribution. Although the step wave signal is replaced by square wave signal, which reduces the subdivision degree of single-phase operation, the purpose of subdivision drive control of stepping motor can also be achieved because of the joint work of four-phase windings of stepping motor.
Ending of intransitive verbs
At present, the application of stepping motor is going deep into all aspects of daily life and industrial manufacturing, and the research on stepping motor and its control technology at home and abroad is also making continuous progress. Mastering this knowledge will play a very positive role in future work and life.
refer to
[1] Wu Shouzhen, Zang Yingjie, et al. Electrical artery width modulation control technology [M]. Beijing: Machinery Industry Press, 2002.
[2] Wang Xiaoming. Single chip microcomputer control of motor [M]. Beijing University of Aeronautics and Astronautics Press, 2002.
[3] Li Jianzhong, editor. Principle and application of single chip microcomputer [M]. Xi An: xidian university Publishing House, 2008.
Li Rending, editor in chief. Microcomputer control of motor [M]. Beijing: Machinery Industry Press, 2004.
Huang Yong, Liao Yu, Gaolin. Design of stepper motor motion control system based on single chip microcomputer [J]. Electronic measurement technology, 2008,31(5):150-154.
Did you get a look at him? Motor control technology paper? People still see:
Paper on computer control system
2. Paper on computer control technology
3.plc application technology paper
4. Paper on computer control system
5. Talking about the topic of motor and electric drive.