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Direct Drive Linear (DDL) Motor

            Direct Drive Linear Motor Options

            Two types of linear motors are available, Ironcore and Ironless. Each one
            provides characteristics and features that are optimal depending upon the
            application. Ironcore motors have coils wound on silicon steel laminations,
            to maximize the generated force, with a single sided magnet way.
            Using a patented electromagnetic design, DDL linear motors have the
            highest rated force per size, a high Km motor constant (equals low thermal
            losses), and low cogging forces without the need for skewing of the
   O MO
            magnets. The high thrust forces possible with these motors make them ideal   Ironcore Motor
            for accelerating and moving high masses, and maintaining stiffness during
            machining or process forces. Ironless motors have no iron, or slots for the
            coils to be wound on.

            Therefore, these motors have zero cogging, a very light mass, and absolutely
            no attractive forces between the coil assembly and the magnet way. These
            characteristics are ideal for applications requiring very low bearing friction,
            high acceleration of lighter loads, and for maximizing constant velocity, even
            at ultra low speeds. The modular magnet ways consists of a double row of
            magnets to maximize the generated thrust force and to provide a flux return   Ironless Motor
            path for the magnetic circuit.

            Feedback Types
            All brushless motors require feedback for commutation. The conventional rotary motor typically utilizes a resolver mounted on the rear of the motor
            or Hall effect devices mounted integrally in the coil windings. For a linear motor, commutation feedback can also be accomplished with a variety of
            methods. Digital or linear Hall effect devices are available from Kollmorgen for the DDL motor series which allow the drive electronics to commutate
            the linear motors in a manner identical to rotary motors.

            For exceptionally smooth motion requirements, sinusoidal drive electronics such as the Kollmorgen's AKD  series, using digital Hall effects,
            provide sinusoidal drive currents to the motor for the best constant force and velocity performance. As an alternative, it is typical for linear motor
            applications to have a linear encoder present in the system for position feedback. It is increasingly common today for drive amplifiers, such as the
            AKD digital amplifier, to derive the necessary commutation information directly from this linear encoder, either with or without supplemental digital
            Hall effect devices on startup. Other types of feedback used on linear motor applications include linear Inductosyns, laser interferometers, and LVDT.

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