Exercices Corrigés Électromécanique des Systèmes Automatisées-ESA-OFPPT-PDF - Électromécanique des systèmes automatisés

Exercices Corrigés Électromécanique des Systèmes Automatisées-ESA-OFPPT-PDF

Exercices Corrigés Électromécanique des Systèmes Automatisées-ESA-OFPPT-PDF




Exercices Corrigés  ESA-OFPPT-PDF










Information

 

DC motor without collector or brushless motor

 

Brushless motor portrayal

 

The DC motor without collector, or "brushless DC", which is also sometimes called ECM ("Electronically Commutated Motor"), is similar to the DC collector motor, except that the collector is replaced by an electronic device and this , without any mechanical contact between stator and rotor being necessary.

 

A brushless motor is made up of three main elements:

 

A rotor including permanent magnets

 

A stator including the 3 coils

 

A position sensor.

 

The currents are continuous and directed towards one or the other of the windings of the 3 stages according to the angular position of the excitation motion created by the magnet. The latter is detected by a very straightforward position sensor, consisting of three Hall probes arranged in the bore of the stator and spaced 60 or 120 °.

 

If the replacement works to fulfillment, a rigorously consistent torque can then be produced with the advantage that the control of the machine remains very straightforward and inexpensive.

 

Benefits

 

This motor avoids the disadvantages ts of the DC motor with collector: brushes which wear out, parasites, sparks, braking caused by friction of the collector on the brushes,….

 

The position of the motor is perfectly known. This offers possibilities for precise positioning guidance.

 

This engine is widely used in robot controls.

 

Disadvantage

 

Requires a nourishment and a sequencer

 

Only two of the three stage coils are powered at the same time and produce torque.

 

The resulting couple is formed by the sum of the three commitments and is consistent.

 

To briefly analyze the control of a brush less motor, it suffices to turn the connected motor in principle and check the change of the strains on the 3 commands U, V, W

 

Lexium motion control for brushless motor

 

Presentation

 

Lexium SER brushless motors fitted with Neodymium Fer Bore (NdFeB) magnets offer a reduced power density and speed dynamics in a reduced space requirement meeting all machine needs.

 

Thermal insurance is provided by a sensor integrated into the motors. They support, without ribald of demagnetization a great capacity of overcharge. Lexium SER motors are certified "Perceived" (UR) by the Underwriters Laboratories. They comply with UL1004 standards as well as European orders (e marking).

 

Depending on the model, Lexium SER brushless motors can be fitted with a stopping brake and a speed reducer.

 

Lexium MHDp drives, which are associated with Lexium SER motors, deliver a sine wave ensuring perfect quality of revolution, even at low speed.

 

Principle of determining the motor size according to the application

 

The torque / speed curves are used to determine the correct size of a motor.

 

Standard example, for a supply strain of 400 V three-phase, the useful curves are curves 2 and 5. The timing diagram of the speeds and torques according to motor cycle must also be defined

 

Integrated encoder

 

The motor is fitted, depending on the model, with a position sensor which can be:

 

· A 2-pole resolver ensuring an accuracy of the angular position of the shaft less than + 6 arc minutes.

 

· An absolute encoder (1) high resolution SinCos Hiperface multiturn (4096 visits) ensuring a precision of angular position of the shaft lower than ± 45 seconds of arc.

 

These sensors allow the following functions:

 

· Give the angular position of the rotor so as to achieve synchronization of the transitions.

 

· Measure the standard motor speed via the associated Lexium drive. This data is used by the Lexium speed controller.

 

· If necessary, measure the position information for the position controller of the Lexium drive.

 

· Measure and possibly transmit in incremental or absolute form the position information for the position feedback of a motion control module (fight "simulated encoder" of the Lexium drive).

 

Portrayal

 

Lexium SER brushless motors consisting of a three-phase stator and an 8-pole rotor with Neodymium Fer Bore (NdFeB) magnets.

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