RDDM Rotary Direct Drive Motors
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Rotary Direct Drive Motors

The Perfect Drive for Every Application. INA - Drives & Mechatronics AG & Co. KG, Directly linking the motor and the mov- Models and simulations are integrated a member of the Schaeffler Group, is a ing mass increases the dynamic and into the development process for direct specialist for linear and rotary direct static rigidity, enabling high-perform- drives and positioning systems, making drives. To complement these products, ance positioning movements. the process more efficient. we also offer directly driven positioning Direct drives are low wearing, which systems and all the necessary...

Technical Basics Benefits of Rotary Direct Drives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Characteristics of Rotary Direct Drive Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 General Motor Values – Efficiency Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6...

Benefits of Rotary Direct Drives Operating costs 1. No additional moving parts This reduces the effort of installing, The hollow shaft with a large diameter There is no elasticity, no play, little fric- adjusting and maintaining the drive makes integration or lead-through of tion and no hysteresis in the drive train other assemblies possible (shafts, rotary resulting from transmission or coupling distributors, supply lines etc.). Bearing 2. Minimal wear in the drive train level, generation of force and effective The drive train has a very long service working area may be very close to one...

Characteristics of Rotary Direct Drive Motors Rotary direct drive motors comprise a A suitable guide system for the preser- The design of the rotary direct drive primary and a secondary part. The pri- vation of the air gap between the prima- motors differs depending on whether mary part contains an active coil system ry and secondary part is just as neces- the construction is slotted, slotless or and the secondary part a permanent sary as an angle measuring system for magnetic system. recording the rotor position in order to The motors generate a consistently high In a concentric...

General Motor Values – Efficiency Criteria With certain motor sizes, the torques and power loss generated or heating speed increases, there will also be fre- and the resulting power losses (copper and applies exactly to the linear modula- quency-dependent losses caused by losses) for various operating points in tion range when the motor is stationary changes in magnetisation and eddy cur- part 1 of the technical parameters are (and at lower speeds) as well as at room rent losses (in addition to the copper fixed, regardless of the winding design. losses Pl) which are not recorded in Since...

Winding Designs and Dependencies The attainable final limit speed of each smaller the voltage constants ku caused DC link voltage UDCL. torque motor mainly depends on the by the winding, the higher the attainable With low DC link voltages, the limiting winding design and the DC link voltage limiting speeds are. Since voltage and speed is reduced nearly proportionally. UDCL. Voltage drops inside the motor torque constants correlate, the power The torque develops in various operating increase the voltage requirement as the requirement increases the higher the points from the torque-current...

Torque-Speed Characteristic The speed limits nlp, nlw, nlc are only cal- At high speeds and torques, additional Controlled motor movements require culated in relation to the winding-specif- frequency-dependent heat losses arise sufficient distance (0.8 times the rele- ic parameters. If the motor is not operat- in the motor (caused by eddy currents vant maximum speed) for possible oper- ed in field weakening, then the motor ating points from the sloping range of can be operated using the torques Tp, Taking these thermal losses into account, a further speed limit is pro- The peak torque Tp...

Torque-Current Characteristic The linear range of the characteristic The motor can briefly (in seconds) be curve from the origin (0.0) up to the for large currents is formed as a conse- operated up to operating point (Tp, Ip). quence of saturation in the magnetic cir- This operating point must be used as a torque constant kT. The operating points cuits of a motor. The naturally curved maximum for acceleration phases. of the motor are found here for uncooled range of the characteristic curve is The limit point (Tu, Iu) may never – not operation (Tc, Ic) and cooled operation described in the...

Thermal Motor Protection Monitoring circuits I and II Direct drives are often operated to their thermal performance limit. In addition to this, unpredictable overloads could arise in the process. This involves an additional current load above the permissible continuous motor current. This is why the power electronics for motors should generally have overload protection for monitoring the motor current. At the same time, the effective value (root-mean-square I2t) of the motor current may only exceed the permissible continuous motor current for a short period of time. This type of indirect...

Monitoring circuit II The KTY84-130 is a semiconductor resis- To protect the motor from excess tem- When the motor is at standstill, con- tor with a positive temperature coeffi- peratures, you must define a switch-off stant currents flow through the wind- cient. The measurement is performed limit in the control system. The sensor ings whose size depends on the respec- with delay depending on the type of can only measure in one phase. tive pole position. This is why the motor is not heated up homogeneously, which may lead to the overheating of nonmonitored windings. The PTC and KTY sensors...