步进电机及单片机英文文献及翻译(21页).doc

-步进电机及单片机英文文献及翻译-第 - 19 - 页外文文献： Knowledge of the stepper motorWhat is a stepper motor： Stepper motor is a kind of electrical pulses into angular displacement of the implementing agency. Popular little lesson: When the driver receives a step pulse signal, it will drive a stepper motor to set the direction of rotation at a fixed angle (and the step angle). You can control the number of pulses to control the angular displacement, so as to achieve accurate positioning purposes; the same time you can control the pulse frequency to control the motor rotation speed and acceleration, to achieve speed control purposes.What kinds of stepper motor sub-： In three stepper motors: permanent magnet (PM), reactive (VR) and hybrid (HB) permanent magnet stepper usually two-phase, torque, and smaller, step angle of 7.5 degrees or the general 15 degrees; reaction step is generally three-phase, can achieve high torque output, step angle of 1.5 degrees is generally, but the noise and vibration are large. 80 countries in Europe and America have been eliminated; hybrid stepper is a mix of permanent magnet and reactive advantages. It consists of two phases and the five-phase: two-phase step angle of 1.8 degrees while the general five-phase step angle of 0.72 degrees generally. The most widely used Stepper Motor.What is to keep the torque (HOLDING TORQUE)How much precision stepper motor? Whether the cumulative： The general accuracy of the stepper motor step angle of 3-5%, and not cumulative.Stepper motor to allow the minimum amount of surface temperatureStepper motor to allow the minimum amount of surface temperature：Stepper motor causes the motor temperature is too high the first magnetic demagnetization, resulting in loss of torque down even further, so the motor surface temperature should be the maximum allowed depending on the motor demagnetization of magnetic material points; Generally speaking, the magnetic demagnetization points are above 130 degrees Celsius, and some even as high as 200 degrees Celsius, so the stepper motor surface temperature of 80-90 degrees Celsius is normal.How to determine the stepper motor driver DC power supply： A. Determination of the voltageHybrid stepping motor driver power supply voltage is generally a wide range (such as the IM483 supply voltage of 12 48VDC), the supply voltage is usually based on the work of the motor speed and response to the request to choose. If the motor operating speed higher or faster response to the request, then the voltage value is high, but note that the ripple voltage can not exceed the maximum input voltage of the drive, or it may damage the drive. B. Determination of CurrentPower supply current is generally based on the output phase current drive I to determine. If a linear power supply, power supply current is generally preferable 1.1 to 1.3 times the I; if we adopt the switching power supply, power supply current is generally preferable to I, 1.5 to 2.0 times.The main characteristics of stepping motor： A stepper motor drive can be added operate pulse drive signal must be no pulse when the stepper motor at rest, such asIf adding the appropriate pulse signal, it will to a certain angle (called the step angle) rotation. Rotation speed and pulse frequency is proportional to. 2 Dragon step angle stepper motor version is 7.5 degrees, 360 degrees around, takes 48 pulses to complete. 3 stepper motor has instant start and rapid cessation of superior characteristics.Change the pulse of the order of 4, you can easily change the direction of rotation.Therefore, the current printers, plotters, robotics, and so devices are the core of the stepper motor as the driving force.Stepper motor control exampleWe use four-phase unipolar stepper motor as an example. The structure shown in Figure 1: Four four-phase winding leads (as opposed to phase A1 A2 B1 phase phase B2) and two public lines (to the power of positive). The windings of one phase to the power of the ground. So that the windings will be inspired. We use four-phase eight-beat control, ie, 1 phase 2 phase alternating turn, would enhance resolution. 0.9 ° per step can be transferred to control the motor excitation is transferred in order as follows: If the requirements of motor reversal, the transmission excitation signal can be reversed. 2 control schemeControl system block diagram is as follows The program uses AT89S51 as the main control device. It is compatible with the AT89C51, but also increased the SPI interface and the watchdog module, which not only makes the debugging process becomes easy and also more stable. The microcontroller in the program mainly for field signal acquisition and operation of the stepper motor to calculate the direction and speed information. Then sent to the CPLD.CPLD with EPM7128SLC84-15, EPM7128 programmable logic device of large-scale, for the ALTERA company's MAX7000 family. High impedance, electrically erasable and other characteristics, can be used for the 2500 unit, the working voltage of +5 V. CPLD receives information sent from the microcontroller after converted to the corresponding control signal output to the stepper motor drive. Put the control signal drives the motor windings after the input, to achieve effective control of the motor. 2.1 The hardware structure of the motor driveMotor drive using the following circuit: R1-R8 in which the resistance value of 320. Q1-Q4 as Darlington D401A, Q5-Q8 for the S8550. J1, J2 and the stepper motor connected to the six-lead。Advantages and disadvantages of stepper motorAdvantages 1. The motor rotation angle is proportional to the number of pulses; 2. When the motor stopped with a maximum torque (when the winding excitation time); 3. Since the accuracy of each step in the three per cent to five per cent, and the error will not accumulate to the next step and thus has better positional accuracy and repeatability of movement; 4. Excellent response from the stop and reverse; 5. In the absence of brush, high reliability, it just depends on the life of the motor bearing life; 6. Motor response only determined by the number of input pulses, which can be used open loop control, which makes the motor and control structure can be relatively simpleSystem cost 7. Just load directly connected to the motor shaft can also be extremely slow synchronous rotation. 8. Speed is proportional to the pulse frequency, and thus a relatively wide speed range.Shortcomings1. If not properly controlled prone to resonance;2. Difficult operation to a higher speed.3. Difficult to obtain high torque4. There is no advantage in terms of volume weight, low energy efficiency.5. Over load will destroy the synchronization, the work will be issued when high-speed vibration and noise.Stepper motor drive requirements(1) to provide fast rise and fall of current speed, the current waveform as close as possible rectangle.For the period ended with the release of the loop current flow, to reduce the winding ends of the back electromotive force, to accelerate the current decay.(2) rhyme with higher power and efficiency.Stepper motor driver, which is the control pulse signal emitted into the angular displacement of the stepper motor, or: the control system sends a pulse signal each through the stepper motor drive to rotate a step angle. That is the stepper motor speed is proportional to the frequency and pulse signals. Therefore, the frequency control pulse signal, to be precise motor speed control; control the number of step pulses to connect the motor accurately. Stepper motor drive there are many, we should take a reasonable choice of power requirements of the drive, the following were introduced various types of typical drive.The latest technological developmentsDomestic and international research on the sub-drive technology is very active, high-performance sub-driver circuit can be broken down into thousands or even any subdivision. Now able to do complicated calculations to make after the breakdown of uniform step angle, which greatly improves the resolution of stepper motor pulses, reduce or eliminate the vibration, noise and torque ripple, the stepper motor is more "class server" feature.The actual role of step angle: in the absence of sub-drive, the user select a different number of phases depends mainly on the stepper motor to meet their own requirements on the step angle，If you use the sub-drive, the user can change the drive number of segments, can dramatically change the actual step angle stepper motor 'phases' of change in the role of the actual step angle is almost negligible. Introduction of AT89C51DescriptionThe AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmels high-density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to many embedded control applications.Function characteristicThe AT89C51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator and clock circuitry. In addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The Power-down Mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset.Pin DescriptionVCC：Supply voltage.GND：Ground.Port 0：Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as highimpedance inputs.Port 0 may also be configured to be the multiplexed loworder address/data bus during accesses to external program and data memory. In this mode P0 has internal pullups.Port 0 also receives the code bytes during Flash programming,and outputs the code bytes during programverification. External pullups are required during programverification.Port 1Port 1 is an 8-bit bi-directional I/O port with internal pullups.The Port 1 output buffers can sink/source four TTL inputs.When 1s are written to Port 1 pins they are pulled high by the internal pullups and can be used as inputs. As inputs,Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pullups.Port 1 also receives the low-order address bytes during Flash programming and verification.Port 2Port 2 is an 8-bit bi-directional I/O port with internal pullups.The Port 2 output buffers can sink/source four TTL inputs.When 1s are written to Port 2 pins they are pulled high by the internal pullups and can be used as inputs. As inputs,Port 2 pins that are externally being pulled low will source current, because of the internal pullups.Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16-bit addresses. In this application, it uses strong internal pullupswhen emitting 1s. During accesses to external data memory that use 8-bit addresses, Port 2 emits the contents of the P2 Special Function Register.Port 2 also receives the high-order address bits and some control signals during Flash programming and verification.Port 3Port 3 is an 8-bit bi-directional I/O port with internal pullups.The Port 3 output buffers can sink/source four TTL inputs.When 1s are written to Port 3 pins they are pulled high by the internal pullups and can be used as inputs. As inputs,Port 3 pins that are externally being pulled low will source current (IIL) because of the pullups.Port 3 also serves the functions of various special features of the AT89C51 as listed below:Port 3 also receives some control signals for Flash programming and verification.RSTReset input. A high on this pin for two machine cycles while the oscillator is running resets the device.ALE/PROGAddress Latch Enable output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming.In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external Data Memory.If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.PSENProgram Store Enable is the read strobe to external program memory.When the AT89C51 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.EA/VPPExternal Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset.EA should be strapped to VCC for internal program executions.This pin also receives the 12-volt programming enable voltage(VPP) during Flash programming, for parts that require12-volt VPP.XTAL1Input to the inverting oscillator amplifier and input to the internal clock operating circuit.XTAL2Output from the inverting oscillator amplifier.Oscillator CharacteristicsXTAL1 and XTAL2 are the input and output, respectively,of an inverting amplifier which can be configured for use as an on-chip oscillator, as shown in Figure 1.Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 2.There are no requirements on the duty cycle of the external clock signal, since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed.Figure 1. Oscillator Connections Figure 2. External