RBE Series Motors Brochure en-US 2003 | Electric Motor

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  R BE( H )   S er i e s   Motor s The RBE series brushless motors provide a wide range of flexible motor solutions for framelessDDR(Direct Drive Rotary) motor applications.ã 10 frame sizes from 21.3mm to 239mm outside diameterã Continuous Torque range from .01Nm to 38Nmã Peak Torque range from .03Nm to 200Nmã Speeds up to 35,000rpmã Standard and custom windings to match speed/torque performanceThese motors come in either housed (RBEH) or frameless (RBE) mechanical configurations. TheHoused models come with stainless steel shafts and can include any combination of Hall sensors,encoder, or resolver as rotor position feedback devices.The frameless configuration is supplied as two separate components (rotor and stator) and does notinclude a shaft, bearings, or endbells. Frameless motors are integrated directly with the load wherethe same bearings which support the load also support the motor. This configuration eliminatesshaft, bearings, endbells, and couplings offering reduced volume, weight, complexity and alsoresults in improved servo stiffness and quicker response. Frameless motors can include integralHall sensors and additional position feedback devices such as encoders or resolvers would beadded as separate components. Data P ubli c ation  INTRODUCTION www  . DanaherMotion  .  c om ã 815-226-2222 RBE(H) Motor Series 2 Advantages of Brushless Systems Brushless systems offer distinct mechanical advantages overconventional systems. Placement of brushless windings intothe outer stationary member and field magnets onto the innerrotating member allows significant reductions in rotor iner-tia and increases in acceleration. Winding heat can be trans-ferred directly from the outer member into adjacent heatsinks. Cooling and efficiency are improved. Generally,brushless systems can provide extra performance while sur-viving a great variety of operating conditions and offerimproved efficiency and heat dissipation. Kollmorgen’sbrushless motors are available frameless or housed and areeasily matched with Kollmorgen servo amplifiers. As newtechnologies emerge, Kollmorgen will continue providingthe very finest motion control system components. Brushless MotorSystem Components There are four basic components in a brushless motor drivesystem. They are the Armature, the Field, the Rotor PositionFeedback and the Servo Amplifier. The Armature The armature is the wound member of the motor and consistsof a three phase windings wound on a laminated iron core.The armature is the outer member and is stationary. It con-sists of low loss laminations bonded into a core which mayhave skewed winding slots. The core and slots are electri-cally insulated prior to inserting the winding. The windingconsists of series of coils for each motor phase. Phase inter-connections are made inside the winding, resulting in a“wye” or “delta” connection. With a three wire termination,there is no reason for the customer to require either a “wye”or “delta” internal connection. Three leads are typicallybrought out for connection to the amplifier. The Field The field assembly or rotor typically consists of permanentmagnet poles bonded to a flux carrying yoke ring. The mag-net material selected will depend upon the application.Available magnet materials include Samarium Cobalt andthe new high energy Neodymium-Iron-Boron compounds.For high speed applications, a magnet retaining band can beplaced around the rotor to insure mechanical integrity. RotorPosition Feedback High performance Brushless DC systems require rotor posi-tion feedback to the amplifier to perform the commutationfunction, which is required for the Brushless DC motor torotate. Kollmorgen Brushless DC motor systems typicallywill include one of the following rotor feedback configura-tions: Hall sensors, encoder, or resolver. Hall sensors havethe advantage that they are an integral part of the Armatureand therefore do not require the customer to integrate a sep-arate feedback device. For frameless motor applicationswhich require a resolver or encoder, the customer will oftenneed to add these as separate components in their system. Servo Amplifier The servo amplifier is required for a brushless motor torotate. The servo amplifier acquires the rotor position feed-back. This information is used to direct current into theappropriate windings of the Armature to develop torque. Asthe Rotor rotates, the Servo Amplifier uses the Rotor Posi-tion Feedback to redirect the current into a different windingphase, as necessary to continue to generate torque as therotor rotates. The Servo amplifier will typically close aninternal current loop. Optionally, the Servo amplifier canuse the Rotor Position Feedback to control the velocity and /or the position of the motor.  INTRODUCTION www  . DanaherMotion  .  c om ã 815-226-2222 RBE(H) Motor Series 3 Frameless vs. Housed Kollmorgen brushless motors can be supplied either frame-less or housed. Ahoused motor includes a shaft, bearings,and endbells along with any feedback devices, into an inte-gral assembly. This is the classical motor configuration. Thecustomer mounts the motor housing into the desired systemand provides a mechanical coupling to the motor shaft. Thecoupling can be a direct shaft coupling, gearing, or belts /pulleys. In many applications, the customer mounts the loaddirectly to the motor shaft with the motor bearings support-ing the load. Frameless motors are supplied as two separatecomponents; the Rotor (Field) and Stator (Armature). TheFrameless motor does not include shaft, bearings, or end-bells. Frameless motors are used in applications where thecustomer desires to minimize the size and weight of themotor and / or obtain the maximum dynamic performance.Since the load is often supported on its own bearing struc-ture, the Frameless motor can be integrated directly onto thesystem / load shaft and be suspended on the same bearingsas the load.This eliminates the need for an additional shaft, bearings,endbells, and any coupling between the motor shaft and theload. An advantage of Frameless motors is that, since thereis no coupling between the shaft and the load, torsional playbetween the motor and load is minimized resulting inimproved dynamic performance. Another advantage of Frameless motors is that inertia matching between the motorand load, which is typically required for housed motor appli-cations, is not a critical requirement for Frameless motorapplications, since the motor and load are one inertial mass. System Performance and Communication Careful selection of system components optimizes brushlesssystem performance. Kollmorgen offers brushless compo-nents for two kinds of brushless systems: six step (trape-zoidal) and sinusoidal. Selection should be made based onthe application and on the performance requirements. Formost servo applications, a six step sequence is appropriateunless very smooth operation under load at slow speed isrequired. For such applications, sinusoidal amplifiers withselected brushless motors offer exceptionally smooth opera-tion with low torque ripple.Brushless motors are not commutated mechanically, such aswith a commutator and brushes, but electronically based onrotor magnet position information. Kollmorgen six stepamplifiers are designed to utilize Hall device position signalsfor commutation. Hall devices mounted onto the stator con-vey rotor magnet position to the amplifier. This positioninformation is necessary for commutation which changes thedirection of current flow in the proper motor windings at theproper time. The Hall devices are accurately aligned withthe stator winding back EMF at the factory on all motorssupplied with Hall devices.The Hall device and Motor Phase Output diagram showsproper alignment of the three Hall device outputs with thethree motor back EMFwaveforms. Externally rotating themotor field generates a back EMF voltage in each phase,which is used to align the Hall sensor in the optimum posi-tion. Current supplied to each phase will correspond withthe Hall device switching points.External motor phase connections are labeled A, B, and C,“V-AB” refers to the backEMFvoltage produced acrossleads Aand B. “V-BC” and “V-CA” denote voltages pro-duced across leads B and C and across C and Arespectively.Corresponding Hall device outputs are labeled “H-AB”, “H-BC”, and “H-CA”.Kollmorgen sinusoidal amplifiers are designed to utilizeresolver or encoder / Hall sensor position information forcommutation. This feedback may be customer supplied orfactory supplied for housed brushless motors. Feedbackselection will vary depending on the motor selected and theapplication. Motor selection for a sinusoidal system mayrequire factory consultation to assure performance goals aremet. Although six step commutation systems can providetorque with ripple as low as five or six percent, sinusoidalsystem torque ripple can approach values of one percent.Amplifiers for both system types are pulse width modulated.  INTRODUCTION www  . DanaherMotion  .  c om ã 815-226-2222 RBE(H) Motor Series 4 MotorParameters Motor parameters are listed on the individual data page foreach motor. These parameters are dependent upon the sizeand shape of the model, but are independent of the windingused. Following is a brief description of the motor parameters. Maximum Continuous Output Powerat 25°C Ambient(HPRated). This is the maximum continuous power outputbased on a 130°C temperature rise and a standard aluminumheat sink. (Standard heat sink size is listed just above thecontinuous performance curves). The maximum continuouspower output can be increased if additional cooling is provided. Speed at Rated Power (N Rated) is the speed at which themaximum continuous power is output. Maximum Mechanical Speed (N Max) is the maximumspeed which will not compromise rotor integrity. Continuous Stall Torque at 25°C Ambient (Tc) is themaximum constant torque without rotation resulting in asteady state winding temperature rise of 130°C with thestandard aluminum heat sink. The size of the standard heatsink is listed above the continuous performance curve foreach RBE(H) series. The continuous stall torque can beincreased if additional cooling is provided. Peak Torque (Tp) is the maximum torque available from agiven size of motor and is the torque the motor will providewhen peak current Ip is provided. Peak torque is based onthe maximum current density in the winding and is availablefor a maximum duration of 10 seconds. Maximum Torque forLinearKT (Tsl) is the maximumtorque for which Kt will be greater than 90 percent of Kt atlow torque. As the torque increases above Tsl, Kt will dropbelow 90 percent of Kt at low torque and an incrementalincrease in current will yield a reduced increase in torque. MotorConstant (Km) is the ratio of peak torque to thesquare root of power input at 25°C and at stall:Km = Tp/(Pp)^.5This ratio is useful during the initial selection of a motor,because it indicates the ability of a motor to convert electricalpower into torque. Acommon use of Km is to determinehow much power a motor will dissipate in order to generatea certain amount of torque by using the following equation:Watts Dissipated = Torque^2 / Km ^2 Thermal Resistance (Rth) is the ratio of winding temperaturerise to average power losses continuously dissipated fromthe stator. Motor Rth values assume a standard aluminumheat sink which is specified above the continuous speedtorque curve for each RBE(H) series. Customer suppliedsupplemental cooling can reduce the Rth value significantlyresulting in increased continuous speed and torque operation. Viscus Damping (Fi) is the torque loss due to rotationallosses, mostly eddy current, which is proportional to speed.Alower Fi indicates less loss during high speed operation. Maximum Static Friction (Tf) is the sum of the retardingtorques at start-up or at stall within the motor. In a framelessbrushless motor, retarding torques consist of magneticfrictional torque and cogging torque. Housed motor TFincludes bearing and other retarding torques. Maximum Cogging Torque (Tcog) is a torque disturbancebased on the magnets in the field attraction to the teeth in thearmature. Cogging torque is minimized in the motor designby strategic selection of slot / pole combinations and byskewing the laminations in the armature. Numberof Poles (P) is the number of magnetic poles in thefield. The electrical cycles per revolution is equal to thenumber of poles to the number of poles divided by 2.
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