Månadsvis arkiv: september 2016
AC motors are powered with alternating present and convert electrical power into mechanical power. You will find 3 kinds of alternating present motors with three-phases. AC induction motors probably the most generally utilized, for AC voltage, the voltage on which they run, is readily accessible at any outlet. All AC motors, regardless of their kind, are comprised of a stator, which produces the magnetic field, along with a rotor, that is produced to rotate by the magnetic field that’s induced in the present generated by the stator.
When selecting the proper stepper motor drive for the application you will find two important elements to bear in mind; the operating speed, or how quick the motor will turn as measured in RPMS, and also the beginning torque, or just how much force is required (if any) to begin the motor. By supplying these specifications to an skilled engineer, you are able to make sure you’ll obtain probably the most efficient and price effective AC motor for the application.
In contrast to toys and flashlights, most houses, offices, factories, as well as other buildings are not powered by small batteries: they are not supplied with DC present, but with alternating present (AC), which reverses its path about 50 occasions per second (having a frequency of 50 Hz). If you would like to run a motor out of your household AC electrical energy provide, rather than from a DC battery, you’ll need a various style of motor.
In an AC motor, there is a ring of electromagnets arranged about the outdoors (creating up the stator), that are developed to create a rotating magnetic field. Inside the stator, there is a strong metal axle, a loop of wire, a coil, a squirrel cage produced of metal bars and interconnections (just like the rotating cages individuals occasionally get to amuse pet mice), or some other freely rotating metal component that may conduct electrical energy. In contrast to inside a nema 17 stepper, exactly where you send energy towards the inner rotor, in an AC motor you send energy towards the outer coils that make up the stator. The coils are energized in pairs, in sequence, creating a magnetic field that rotates about the outdoors from the motor.
How does this rotating field make the motor move? Keep in mind that the rotor, suspended inside the magnetic field, is definitely an electrical conductor. The magnetic field is continuously altering (simply because it is rotating) so, based on the laws of electromagnetism (Faraday’s law, to become precise), the magnetic field produces (or induces, to make use of Faraday’s personal term) an electric present inside the rotor. When the conductor is really a ring or perhaps a wire, the present flows about it inside a loop. When the conductor is merely a strong piece of metal, eddy currents swirl about it rather. Either way, the induced present produces its personal magnetic field and, based on an additional law of electromagnetism (Lenz’s law) tries to quit what ever it’s that causes it’s the rotating magnetic field by rotating also. (You are able to believe from the rotor frantically attempting to ”catch up” using the rotating magnetic field in an work to get rid of the distinction in motion in between them.) Electromagnetic induction will be the important to why a motor like this spins and that is why it is known as an induction motor.
A programmable logic controller (PLC) or programmable controller is a digital computer that is used to automatically regulate the industrial process. For example, comtrolling machinery on assembly lines of factor. This controller is designed to meet a range of industrial activities such as multiple inputs and output arrangements, extended temperature ranges, giving immunity to electrical noise, and providing resistance to vibration. The programs, designed to regulate the machine operation, are usually stored in a battery-backed or non-volatile memory. A PLC is an instance of a real time system becuase output results are needed to be produced in response to input conditions within a time-bound period; else, it will result in an unintended operation. Over the years, the functionality of PLC has evolvoed to accommodate sequential relay control, motion control, process control, distributed control systems, and networking. In PLC, microprocessor controlled interface is inbuilt and is designed to control or monitor some other I/O functions. Being an industrial computer control system, it always monitors the state of input devices and makes decisions on the basis of custom program for controlling the state of devices connected as outputs.
Inserting Parametric PLC Modules
AutoCAD Electrical can generate PLC I/O modules in different graphical styles through parametric generation technique on demand. These modules are generate by a database file and a library of symbol blocks. PLC I/O modules can be inserted as independent symbols. PLC modules behave like other schematic components. These modules are AutoCAD blocks containing attributes for connection points, tagging and so on.
The Insert PLC (Parametric) tool is used to insert a PLC module parametrically. To do so, choose the Insert PLC (PLarametric) button from the Insert Components panel of the Schematic tab; the PLC Parametric Selection dialog box will be displayed, as shown in Figure 10-1. Using this dialog box, you can select the PLC Module and its graphics that you want to insert in a drawing. The different options and areas in this dialog box are discussed next.
Manufacture Catalog Tree
The Manufacture Catalog tree, shown in Figure 10-2, displays a list of PLC modules. This list can be filtered by selecting the manufacturer, series, and type of PLC. The data displayed in the Manufacturer Catalog tree is stored in the ace_plc.mdb database file.
You can selet a PLC module from the Manufacturer Catalog tree. To do so, click on the + sign on the requried manfacturers module; PLC modules of the selected manafacturer will be displayed. Select the requried module from the module list; the detailed information of the selected module will be displayed at the lower part of the PLC Parametric Selection dialog box, as shown in Figure 10-3.
After specifying the required values in the I/O Point dialog box, choose the OK button from this dialog box; the I/O Address dialog box will be displayed, as shown in Figure 10-6. Using this dialog box, you can specify the address for the first I/O point. Fasttobuy offers different brands of PLC modules such as Siemens PLC, Omron PLC, Mitsubishi PLC, Delta PLC, SIEMENS PLC, Omron PLC, Fatek PLC, ect.
The values in the Quick picks drop-down list are based on the values that you have specified in the I/O Point dialog box in the Rack and SLOT edit boxes. Select the required value from the Quick picks drop-down list; the value will be displayed in the Beginning address edit box. Alternatively, enter a required value for the first I/0 address of a PLC module in the Beginning address edit box. Note that the other I/O points of a module will be incremented based on the value specified in the Beginning address edit box.
Choose the List button in the I/O Address dialog box; the Report Generator dialog box will be displayed. This dialog box display the information of the selected PLC module.
After specifying the required options in the I/O Address dialog box, choose the OK button in this dialog box; the selected PLC module will be inserted into the drawing.
Hybrid stepper motors provide excellent performance in areas of torque, speed, and step resolution. Typically, step angles for a hybrid stepper motor range from 200 to 400 steps per revolution. This type of CNC stepper motor provides a combination of the best features available on both the PM and VR types of stepper motors.
Figure 8.1 shows a simplified construction of a unipolar hybrid stepper motor.The rotor of this machine consists of two star-shaped milled steel pieces with three teeth on each. A cylindrical, axially magnetized PM is placed between the milledpieces making the end of each rotor either a north or a south pole. The teeth areoffset at the north and south ends as shown in Fig. 8.1. The stator has four poles, each of which has a center-tapped winding. Since all the windings have the commonconnection V+, only five wires, A, B, C, D, and V+, leave the motor. A winding is excited by sending current into the V+ wire and out one of the other wires. Thewindings are wound in the stator teeth in such a way so that the Closed Loop Stepper motor behaves in the following way:
If winding A or C is excited, pole 1 or pole 3 is energized as south.
If winding B or D is excited, pole 2 or pole 4 is energized as
Stepper motors are also classified with respect to the stator windings as being either bipolar or unipolar.Bipolar stepper motors have two windings with anopposing magnetizing effect in each pole, while unipolar stepper motors use only one winding per pole.
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Leadshine NEMA34 3 phase Hybrid Stepper motor Drive kits 863HBM80H-1000+HBS2206
The HBS series offers an alternative for applications requiring high performance and high reliability when the servo was the only choice, while it remains cost-effective. The system includes a 2-phase stepper motor combined with a fully digital, high performance drive and an internal encoder which is used to close the position, velocity and current loops in real time, just like servo systems. It combines the best of servo and stepper motor technologies, and delivers unique capabilities and enhancements over both, while at a fraction of the cost of a servo system.
Stepper based servo control
Direct 120 / 220 / 230 AC input, or DC to 100V
Closed position loop to eliminate loss of synchronization
No torque reservation
Load based output current for extra low motor heating
Smooth motor movement and low motor noise
Quick response and no hunting
No overshooting and almost zero settling time
High starting torque, high inertial loads
Capable of driving NEMA 23, 24, 34, and 42 easy servo motors (stepper motors with encoders)
Plug-and-play, no tuning for most of applications
2 Phase Encoder closed loop Stepper Motor+Drive Kit Engraving Machine
2HSS two phase hybrid stepper servo drive system integrated servo control technology into the digital step driver. It adopts typical tricyclic control method which include current loop,speed loop and position loop.This product has the advantage of both step and servo system, is a highly cost-effective motion control products.
Full closed loop
1.Accurate position and speed control can achieve the most strict request of the application.
2. High robustness’s servo control adapt to wide range change of inertial load and friction load.
3.The motor with 1000 CPR encoder,support vector closed loop control. Compare with traditional step motor, it solved the problem of lose step.
Low heat/high efficiency
1.Adjust the current according to actual load,the heat is much lower compare with traditional step motor.
2.The current is almost 0, and without heat under stop condition.
3.It save energy and can achieve nearly 100% torque output. Working smoothly and accurate.
Fasttobuy Co .,Ltd . was established with the vision of developing motion control product for the industry .Our company has accumulated several years of experience in this field , integrating research and development, manufacture and marketing. We are always striving to understand the needs of customers, and to develop further in this field.
Our main products are stepper motor drives, step motor, AC servo motor systems, DC brushes and brushless motors and drive systems, and intelligent step motors .we also provide complimentary mechanical products, such as motor couplings, gearboxes, and linear motions.
One advantage of a gear reduction starter motor over a direct drive motor is reduced mass (weight) of the gear reduction motor.
Another advantage of using a Gear reduction motors is that an increased engine cranking speed over TDC of each engine compression stroke can be obtained, even though the average cranking speed remains about the same as a comparable direct drive motor. This increase in speed over TDC is said to improve the cold start performance of a diedsel engine.
Gear reduction starter motors are also more efficient than direct drive motors. This means that less of the electrical energy that is being converted to mechanical energy is lost as heat. One starter motor manufacturer indicates up to a 40 percent decrease in planetary gear Motor current with the gear reduction motor compared to a comparable direct drive motor. This means less current is also flowing through the cranking circuit, so the available voltage at the starter motor terminals is increased compared to direct drive starters.
Most gear reduction starter motors are soft start motors. The soft start design cuases the armature to rotate slowly as the drive with attached pinion gear is sliding toward the ring gear. This slow rotation of the pinion gear provides a greater likelihood that the pinion gear is fully engaged with the ring gear before fully cranking power is applied, which reduces ring and pinion gear milling. Howerver, the soft-start design also causes most gear reduction starter motors to draw much more current through the motor’s solenoid terminal compared to most direct drive starter motors.
Servo motors have serval distinct characteristics that sperate them from their stepper counterparts. The biggest is the lack of direct gearing between the rotor and the output shaft. This eliminates the backlash and cogging behaviors found ins steppers, where there is period of slop between the gear teeth before movement actually begins, and where the shaft continues to move after the Delta servo motor has stopped. This can lead to jerky starts and stops, as well as a time delay in movement. This does not impede static positioning performance markedly, but it presents major issues when on-the-fly velocity changes or hard starts/stops are needed.
A model of a typical radial brushless DC servo motor is shown before in figure 1.1 For a long time, servo motors used brushes to transfer current from the static winding to the rotor, but this would lead to wear on the brushes, in turn shortening the lifespan of the motor. With the advent of electronic motor controllers, the brusheless design was adopted, which uses control electronics to vary the currents phases to the motor’s windings in the same way the brushes do. For the rest of this paper, all mention of mitsubishi servo drives will be of the brusheless type.
Looking at figure 1.1 below, there are several objects of interest. First are the armature windings (held by the stator), which create a magnetic field that travels through the air gap to the permanent magnets on the rotor. Even though there are normally no gears in a servo motor, cogging can still exist, as there are gaps between the magnets on the rotor where the flux decrease, though this only becomes noticeable at low speeds. This type of congging in servos is perhaps more accurately termed ”detent torque.” There are two ways to minimize this type of cogging, the most common being the addition of some gearing to the drive shaft. This allow the motor to run at a higher speed out of its cogging region, but does not compromise power output or precision, thought it can induce some backlash. The other way of minimizing cogging is to skew the magnets on the rotor so that a radial line from the center of the rotor always intersects a magnet at least once. When using a motor without gearing, it is known as a direct drive motor. This allows for the best transfer of power to the load, and avoids any of the negative aspects of gearing previously mentioned. A feature in newer servo motors (including the Bodine models used in this thesis) is the use of an ironless stator, which eliminates iron saturation, a situation where the magnetic properities of the iron limit how much current can be applied to the windings. Inducing iron saturation too ofen will cause overheating and possibly damage the winding or magnets. With an ironless stator, rotor magnet skewing is not necessary, as the magnetic fields aren’t influenced by the material of the stator. Also, since the only mechanical connection between the shaft and the body is through the bearings, friction is very low (especialy when using ball bearings).
In high torque motors such as the ones used in this thesis, the rotor actually consists of two plates of permanet magnets sandwiching the stator, which allows for a major increase in torque. This feature only exists in axial flux motors, due to the design where the stator lies in between the rotors, whereas in radial flux servos, the rotor is completely enclosed by the stator. The majority of the heat dissipated from a servo motor comes from the stator, so its outside location adis in cooling. In fact, the main limiting fator in the power of a servo motor is the heat capacity of the stator and the armature windings.
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Induction Servo Motors are the most commonly used motors in many applications. These are also called as Asynchronous Motors, because an Induction Leadshine servo motor always runs at a speed lower than synchronyous speed. Synchronous speed means the speed of the rotating magnetic field in the stator.
Principle of Induction Servo Motor:
When a three phase supply is given to the stator, a rotating field produces induced e.m.f. in rotor windings which cause induced currents tend to propose the action, producing them and therefore they circulate in such a manner that a torque is produced in the rotor tending it to cause it to flow the rotating field and thus reduce the relative motion which is producing the induced currents.
Induction Servo motor speed
Induction Servo motor works as follows: Electricity is supplied to the stator, which produces a magnetic field. This magnetic field moves around the rotor at synchronous speed. Rotor currents produce secondary magnetic field, which is trying to fight the stator magnetic field, which causes the rotor to rotate. However, in practice, the servo motor driver never runs at synchronous speed but the ”base rate” is lower. The difference between the two speeds is the ”slip / slide” that increases with increasing load. Slip only occurs in an Induction Servo motor. To avoid slip ring can be fitted a sliding / slip ring, and the motor is called ”motor slip ring / slip ring motor”.
The following equation can be used to calculate the percentage of slip / slide (Parekh, 2003):
% Slip = (Ns – Nb) / Ns x 100
Ns = synchronous speed in RPM
Nb = base speed in RPM
The relationship between load, speed and torque
graph torque vs. speed three-phase AC Induction Servo motor with the current set. When the motor (Parekh, 2003):
• Start turns lights are flame high initial currents and low torque (”pull-up torque”).
• Achieve 80% of full speed, the torque is at the highest level (”pull-out torque”) and the current begins to drop.
• At full speed, or synchronous speed, torque and stator currents down to zero.
The stator of an Induction Servo motor consists of poles carrying supply current to induce a magnetic field that penetrates the rotor. To optimize the distribution of the magnetic field, the windings are distributed in slots around the stator, with the magnetic field having the same number of north and south poles. Induction Servo motors are most commonly run on single-phase or three-phase power, but two-phase motors exist; in theory, Induction Servo motors can have any number of phases. Many single-phase motors having two windings can be viewed as two-phase motors, since a capacitor is used to generate a second power phase 90° from the single-phase supply and feeds it to the second motor winding. Single-phase motors require some mechanism to produce a rotating field on startup. Cage Induction Servo motor rotor’s conductor bars are typically skewed to reduce noise.