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 and electric motors.

Electromagnetic Actuators

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Description

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)

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Description

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

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Description

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

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Description

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

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Description

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

MRF Technologies

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Description

Magneto rheological fluids (MRF) allows to build new applications as active valves, smart hydrostatic or hydrodynamic bearings… CEDRAT TECHNOLOGIES has realised MRF fluids characterisation and customised MRF applications for machine tools.

Applications

Active MRF valves, smart hydostatic or hydrodynamic bearings

Status
Proof of concept

MRF Actuators

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Description

The presented Magneto Rheological Fluid (MRF) Actuator is a new self locking braking linear magnetic actuator requiring very low electric power (<2W) to manage up forces to 100N. It is suited to make fail safe shock absorbers & dampers.

Applications

Active Damper, Shock Absorbers, Locking mechanisms ...

Status
Proof of concept

Limited Angle Torque Actuators: LAT

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Description

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

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Description

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

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Description

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

Magnetostrictive Actuators

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Description

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

Linear amplifier for magnetic actuators: LA24

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Description

The multi-channel Linear Amplifier LA24 is designed as a low noise, high bandwidth linear amplifier for finely driving every magnetic actuator from CEDRAT TECHNOLOGIES.

Applications

Positioning, Stabilization

Status
Product

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

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Description

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