Magnetic actuators & motors

Magnetic Actuators use magnetic effects to generate forces which impact on the motion of a part in the actuator.

The first large family of magnetic actuators is based on the magnetic forces acting at distance, the Laplace-Lorentz forces and the reluctance forces. Linear types offer strokes in the range of 1 to 20mm, and are complementary to piezo actuators. They can be sorted in 3 categories:

  • Moving coil actuator : Placed in static magnetic field, a mobile coil driven by a current is submitted to the Laplace-Lorentz force. This force is proportional to the applied current. Thus these actuators are controllable. Since first applications were loud-speakers, they are also called voice-coils. CEDRAT TECHNOLOGIES has developed high performance Voice Coils (also called Moving Coils) and LAT Limited Angle Torque actuators for various automotive, industrial or space applications.
  • Moving magnet actuator : Placed between two magnet poles, a mobile permanent magnet can be switched from one pole to the other using coils. Such moving magnet actuators are bi-stable. They present high forces but are not so controllable. Miniature devices have been developed by CEDRAT TECHNOLOGIES for locking and haptic applications.
  • Moving iron actuator : A soft magnetic part placed into a coil system naturally moves in a way that minimises the system magnetic energy. In standard electro-magnets, this reluctance force is larger than the Laplace force but it is only attractive and not controllable. The new MICA™ Moving Iron Controllable magnetic Actuator developed by CEDRAT TECHNOLOGIES thanks to Oseo is an innovative biased (polarised) electromagnetic actuator in which the force can be reversed all along the stroke. It is used for vibrations generation or for active damping in embedded applications. It offers larger strokes than piezo actuators. It offers higher forces and much less heating than any Moving coil actuator.

The second family of magnetic actuators is based on magnetically-controlled active materials. Two types are used by CEDRAT TECHNOLOGIES for innovative devices :

  • Magnetostrictive actuator : These actuators use the magnetostrictive effect, which consists in the deformation of a magnetostrictive material when subjected to a magnetic effect. For example magnetostrictive deformation of Terfenol-D achieves 1600ppm, making this active material an interesting competitor of piezoelectric PZT ceramics for high power transducers or low voltage actuators.
  • Magneto Rheological Fluid Actuator : A Magneto Rheological Fluid (MRF) can solidify when subjected to a magnetic field. This effect can be used to design various MRF-based actuators : valves, brakes, clutches, semi-active dampers, smart hydrostatic / hydrodynamic bearings…

The third broad family of magnetic actuators is the electric motors also called electric rotating machines. CEDRAT TECHNOLOGIES computes all sizes as services but develops only small electric motors, such as Brushless DC motors (BLDC) and stepper motors.

These technologies are presented in the examples hereafter. You can also download our Piezo and magnetic products catalogue. Furthermore, publications are available on magnetic actuators.

Magnetic fast steering mirror M-FSM62

To offer an alternative to piezo DTT for fast steering mirrors (FSM), CTEC develops also magnetic actuators based FSM: the M-FSM. The M-FSM mechanism volume contains the mirror, the actuators, the guiding and the Eddy Current position Sensors (ECS) position sensors.

Applications

Free Space Optic (FSO) communication links,laser guide star, laser designators…

STATUS

Product

Switching power amplifier for magnetic actuator CSA96-ES

The Compact Switching Amplifier CSA96 is a compact size and large output power amplifier box for driving linear magnetic actuators like Moving Iron Controllable Actuator (MICA™). This CSA96 box is supplied by an External DC power supply up to 96 VDC.

Applications

Current amplifier for magnetic actuators

STATUS

Obsolete

Electromagnetic Actuators

CEDRAT TECHNOLOGIES develops customised ElectroMagnetic Actuators, which are dedicated to customer’s specific applications when off the shelves standard products are not suitable. They cover a wide spectrum of applications and markets such as industry, automotive (for example, e-Lift 3 project with PSA), air & space, medtec, etc.

Applications

Valve actuation, locking and unlocking Pin-puller, contactor…

STATUS

Product

Moving Iron Controllable Actuator technology (MICA)

MICA™ actuator fullfills requirements in which compact, highly dynamic, precise, reliable and robust actuators are needed. This technology has been designed to fill the gap between the well known voice coil and the solenoid technologies.

Applications

Valve control, pump and compressor actuation, test benches, vibration generation, active control of vibrations, fast gripper, fast positioning…

STATUS

Product

BRUCE - Electromagnetic Actuated Pin Puller

Upon request of CNES, the French National Space Agency, CEDRAT TECHNOLOGIES has designed a resettable electromagnetic actuated pin puller, called BRUCE (Broche Rétractable Utilisant une Commande Electromagnétique)

Applications

Space, electomagnetic, pin puller… 

STATUS

Prototype

Voice Coils actuators

The Moving Coil Actuator is based on the Lorentz-Laplace force, which is strictly proportional to the applied current. This is the most usual linear magnetic controllable actuator. Several CEDRAT TECHNOLOGIES voice coils have been developed for space application (ex MTG, IASI).

Applications

High linearity actuators, Aerospace…

STATUS

Space evaluated

Bi-stable Linear Moving Magnet: BLMM

The Moving Magnet Actuator is based on a permanent magnet moving between two opposite electromagnets. It is a bistable magnetic actuator with high force at rest. CEDRAT TECHNOLOGIES’s BLMM are miniature linear actuators.

Applications

Locking mechanisms, Vibrations generators, Micro-valves…

STATUS

Product

Limited Angle Torque Actuators: LAT

The Limited Angle Torque (LAT) actuator offer a rotating motion over an angle of +/- 15°. Thanks to its principle and an elastic guiding, it offers a smooth, high resolution rotative motion and precise pointing assemblies for air & space & optic applications.

Applications

High resolution rotating motion, Micro nano Positioning, Pointing, Scanning

STATUS

Prototype

Brushless DC Motors Upgrade

CEDRAT TECHNOLOGIES upgrades Commercially Of The Shelves (COTS) BLDC Brushless DC motors for improving torque & speed and for reducing electric power, by means of FLUX FEM re-design, parts changes and tests on benches for micro rotating motors.

Applications

BLDC Micro Motors for demanding applications : air & space, UAVs 

STATUS

Prototype

Single Phase Stepper Mini-Motor: SPSM-1

A single phase rotating stepper micro motor featuring axial tunable air gap and flat permanent magnet has been developed in FP6 M2EMS EC project, in collaboration with CEA and ETA. This stepping motor is compatible with Si technologies.

Applications

Micro-Motors, Micro-technologies…

STATUS

Proof of concept

Battery-based power supplies for embedded actuators, sensors & mechatronic systems

Power supplies for piezo or magnetic actuators, sensors & mechatronic systems based on 3.7V (typical) lithium polymer cells voltage.

Applications

Embedded piezo & magnetic actuators, motors, sensors, mechanisms, valves

STATUS

Proof of concept

Magnetostrictive Actuators

CEDRAT TECHNOLOGIES’ Magnetostrictive actuators are solid state magnetic actuators based on Terfenol-D Giant Magnetostrictive Materials. They can be designed to produce high forces (>20kN) & large strokes (>200µm) at low voltage (<12V) in static or dynamic.

Applications

High Force Generator, Low Voltage actuators, Sound transducers (sonar) …

STATUS

Prototype