The basic parts of a telescope are the optical system and a mechanical support. Most stepper motors have 200 fullsteps per revolution. In this method, the starting torque is very low and it is not very. Choose the driving system, by synchronous, stepping, or dcmotor. Ac timing motors in a round case configuration with either twohole modeld or fourhole modela mounting plates. Motor selection for telescope drive antique radio forums. Stepper motors are driven at least 10 steps per second. Meade lx200 classic and autostar i combined telescope focuser, 5.
Stepping motor driver chip synchronous timing motors hurst motors air cylinders audiovisual equipment balloons, weather batteries and chargers books breadboards workstations cable, cords, wires capacitors computer components lab equip. Telescope synchronous motor controller electronics forum. We have a range of products to suit driving various motor types that can be. This synchronous motor drive was featured on a model 152c.
Synchronous speed is directly proportinal to frequency,similar ti induction motors constant flux operation below base speed is achiecved by operating the synchronous motor with constant v f ratio. Another method of starting the synchronous motor drives is by external motor. The pull out transformer is not affected by dc but pulses of ac in. These systems have the ability to drive synchronous or stepper motor for the ra drive. The corre sponding induction motor im however, has slip losses and rotates only at 1475rpm for a chosen 30 kw example. To get the complete story on this innovation read my article from sky and telescope magazine feb. The synchronous motor contains fixed stators electromagnets and a rotor also a magnet. It provides basic star tracking and usually higher speed settings for moving. Reliable equipment has always been one of the goals of the atm. Induction motor diy alternator 40 watt low 800 rpm neodymium motor generator conversion duration.
This paper will introduce one redundant synchronous control method for direct drive torque motor of large diameter telescope drive system, which can effectively improve the telescope drive system tracking precision and improve the reliability, stability and antijamming ability. Does anyone remember a discussion along these lines. When it was desired to advance along the ra axis, the second motor was started, increasing the speed of the drive. A drive for a nspolarex model 1 courtesy of stephen brennan. In this method the rotor of the synchronous motor is rotated by an external motor and when the speed of the rotor reaches near synchronous speed, the dcfield is switched on and pull in takes place. Synchronous motors use electrical frequency to regulate the motor speed. The reason for using a stepper motor is the abilty to control it at the correct speed. For those looking for a telescope that has the capability of tracking and finding beautiful night sky objects, this mount is a must have tool. By fitting one of our mains synchronous motors to the worm shaft, an object can be kept in field of view for a prolonged.
Also you will need magnetometer hmc5883l for get reference of azimuth respect to north. In the old days the mount consisted of a knob by which you could adjust the scope to keep track with the stellar objects movement, or if you could afford it, a synchronous motor to drive the telescope east to west following the track of the star call right ascension, ra for short. As far as slewing the telescope, the 16 reflector in the westmont college observatory used a neat trick. Electric motor drives three general types of electric motor are available for driving a telescope. All drives are assembled with hurst synchronous hysteresis reversible motors 110. A telescope controller for synchronous motors springerlink. Synchronous motors contain multiphase ac electromagnets on the stator of the motor that create a magnetic field which rotates in time with the oscillations of the line. In this episode of electronic basics i will show you how a modern and also cmmon hybrid synchronous stepper motor. The schematics, the design of drivers and safety features for the switching elements in the inverter are shown. Ee6703 unit 5 permanent magnet synchronous motors 4 prepared by. Crosscoupled synchronous control of telescopes complex. Get the best deals on motorized telescope mounts when you shop the largest online selection at. Further for automatic telescope you need 3 stepper motors for azimuth. In this method, the starting torque is very low and it is not very popular method also.
One well known approach is the utilization of synchronous motors sm. Awr technology astronomy electronics telescope drive systems. Telescope clock drives from the 1980s or earlier often used ac synchronous motors. Advanced bldc motor drive and control giovanni tomasello applications engineer. Designing a three phase inverter for a permanent magnet. There are two basic types of motor drive systems for telescopes. Advanced bldc motor drive and control stmicroelectronics. If 14 to 12 arc second per microstep, and 10 microsteps per fullstep, and 200 fullsteps per revolution, then one stepper revolution covers 500 to arc seconds. David johnson made this drivecorrector for use with the synchronous motors of his telescope drive. The speed of a synchronous motor is set by the frequency of the. In astronomy, a clock drive is a motorcontrolled mechanism used to move an equatorial mounted telescope along one axis to keep the aim in exact sync with. This device provides three halfbridge drivers that can drive two nchannel mosfets. Whats the difference between asynchronous and synchronous.
Output speeds from the integral gearhead can be chosen from a range of 0. The synchronous motor based products and options have an inverter unit to. This page will feature the various synchronous motor drives that were available for the different models. Telescopes consist of a telescope tube and a mount.
Synchronous squirrel cage rotor induction wound rotor. These commonly available ac motors are used to power timeclocks, record player turntables, and telescopes, anyplace a motor needed to run at a very accurate speed. Celestron ra single axis motor drive for the astromaster telescope. Telescope mountings for amateaur builders iii nasaads. Global electric motor market covid 19 imapct analysis. A synchronous motor achieves its predetermined rpm and stays there. The reduction needed between motor and telescope is 360 degrees divided by the distance one stepper revolution covers. This is the doublearm barn door drive which i invented many years ago. The below diagram shows how a simple two phase synchronous motor orientates the rotor as a function of a changing electric wave.
Celestron nexstar slt computerized telescope compact and portable newtonian reflector optical design skyalign technology computerized hand control mm aperture. Use this small celestron motor drive to automatically track stars as they make their westward movement across the sky. This driver provides both telescope and focuser interfaces each of which may be used by. Siemens 1fk70322ak711bg0 synchronous motor 33mm shaft 6000rpm 3. Synchronous motors contain multiphase ac electromagnets on the stator of the motor that create a magnetic field which rotates in time with the oscillations of. With synchronous motor technology, speed is directly proportional to ac input frequency for example, at 120 vac, 60 hz, an ac synchronous motor will turn at 72 rpm. Nema17 is standard low cost stepper motor mostly you find in 3d printers. When the dc is made to vary synchronously, in our case by a digital method called pulse width modulation, the motor returns to its original smooth running state.
Here is a link to the wikipedia page on hysteresis synchronous motors. Design of one large telescope direct drive control system based on. I have an old telescope, a rather large cave 5 refractor, which has a small 115 volt 60hz synchronous motor on the polar shaft, and a reversible hurst synchronous motor on the declination axis. Navy bureau of ordinance, maybe a torpedo or radar.
Synchronous motor an overview sciencedirect topics. Brand new excess from compass technical, the last producer of weathers products from the 1960s. Pdf permanent magnet synchronous motor control driver. Drive systems can be supplied to drive synchronous, stepper or dc motors. The machine is run up to speed as an induction motor and is then pulled into synchronism to operate as a synchronous motor. Permanent magnet synchronous motor pmsm stator is the same as ac im. A selsyn, or synchro is a motor which when wired to one another and the shaft rotates, the other shaft rotates in synchrony, keeping a constant angular position relationship with the first shaft.
A synchronous electric motor is an ac motor in which, at steady state, the rotation of the shaft is synchronized with the frequency of the supply current. A celestron telescope drive configured as a sidereal rate tracking camera platformthe speed of a synchronous motor is set by the frequency of the powerline, in north america and many other places this is 60hz. The synchronous motor either run at synchronous speed or it will not run at all. This driver provides telescope v3 support, 100% conformance, and compatibility with thesky x 10. For control stepper motors you can use arduino uno or arduino mega with stepper motor driver shield based on a4988 or other drivers from allegro. Clock drives work by rotating a telescope mounts polar axis, the axis parallel to the. The permanent magnet synchronous motor pmsm is excitated by rotor face mounted permanent magnet and has the advantage of small starting current, but starting is difficult, and even more without. The less pricey but still incredible porsche taycan 4s ev. Further for automatic telescope you need 3 stepper motors for azimuth angle, elevation angle and one for change focus for control stepper motors you can use arduino uno or arduino mega with stepper motor driver shield based on a4988 or other drivers from allegro. Synchronous motors are used in applications requiring very precise speed and position control, such as clocks and record player turntables. The ra axis was driven by a synchronous motor through a differential that had a second motor connected to it. Get the best deals on 380 v industrial servo motors when you shop the largest online selection at.
In astronomy, a clock drive is a motorcontrolled mechanism used to move an equatorial mounted telescope along one axis to keep the aim in exact sync. If i remember correctly the gist of the discussion did not favor steppers. Precision telescope clock drives by opticcraft machining. In this paper, one segmented permanentmagnet synchronous motor pmsm, 4m diameter, is suggested for the mount driving. This speed can be varied by varying the frequency, although most applications simply use gearing or a belt or chaindrive system to achieve the desired load speed. These commonly available ac motors are used to power. Whats the difference between asynchronous and synchronous motors. Synchronous motors controlled by variablespeed drives are. The gearbox of the standard motor is quite good, but you would have to ensure that you have some way of connecting to it it features a small drive gear from a small motor shaft and you would also have to work out the gear ratios accordingly. We use cookies to make interactions with our website easy and meaningful, to better understand the use of our services, and to tailor advertising.
Sms with a 4pole rotor operated at 50hz rotate in synchronism with the supply at exactly 1500rpm. Synchronous motor drive is provided by an inverter giving quasi sine wave of equivalent 240v rms or 110v rms output, frequencies within the range 42hz to 80hz with a power up to 8 watts. There are some advantages to using synchronous motors on a telescope drive. Discover the best telescope motor drives in best sellers. The advantages of the synchronous motor are the ease with which the power factor can be controlled and the constant rotational speed of the machine, irrespective of the applied load. This category also includes hand controllers for orion computerized telescope mounts. A singleaxis drive consists of a single motor and driver that attaches to the rightascension eastwest axis of a telescope mount.
It is required for the paramount mounts, and may be used with thesky controlling any other of its supported telescope types, or via its builtin outbound ascom support, and then using ascom telescope drivers. Electronic motor drives provide electronic control of one or both axes of equatorial mounts, eliminating the need for you to manually reposition the telescope to keep objects centered in the field of view. Telescope mountings, drives, and electrical equipment. Telescope drive motors posted in atm, optics and diy forum. I dont remember what forum i was reading but not too longago there was a discussion on what type of motor is best for telescope drives synchronous or stepper. Ra sidereal drive rate determined by telescope reduction ratio, gearbox attached to the motor and torque required for the telescope. Abstract author lars dautermann title designing a three phase inverter.
New energyefficient motor technologies use a synchronous design, putting differences between asynchronous and. Astronomers used a device called a drive corrector to make small changes to the electric frequency and vary the telescope drive speed the celestron c8 page contains additional information about drive correctors. Works with celestron astromaster and powerseeker equatorial telescope systems, as well as any setup that employs celestron cg2 or cg3 equatorial mounts. Threephase brushless dc motor driver evaluation board. Synchronous redundant control algorithm in the telescope. You can get your stepper motor and driver circuit here affiliate links. Efficient, compact ca series hysteresis synchronous motors have a range of standard speeds from 1200 rpm direct drive to rpm geared.
Designing a three phase inverter for a permanent magnet synchronous motor. If youre using heavy duty stepper motors or greater than 5v inputs, i recommend a motor control driver. It was the common use of these motors in telescope drives that led to the. As i am living in australia stepping down mains power 50 hz will not work so i have been trying to.
372 535 997 1433 701 1108 1326 488 1067 596 462 641 802 943 463 1004 104 617 1479 193 467 1440 299 315 180 905 492 73 715 320 1493 798 1096 1129 312 1096 1326