Brushless DC Motor Design
HOW DOES A BRUSHLESS DC MOTOR WORK?
Brushless DC Motor Diagram
WHAT IS THE DIFFERENCE BETWEEN A BRUSHLESS AND BRUSHED MOTORS?
BLDC MOTOR DESIGN
During the brushless DC motor design phase, Portescap engineers aim to optimize the brushless motor torque. Motor torque is the amount of rotational force that a motor generates during operation. The key components involved in producing torque are the magnet, the winding and the flux path. The higher the number of pole pairs in the magnet, the higher the amount of brushless motor torque for the same dissipated power. Copper content of the winding contributes to the power provided by the motor while flux path guides all of the magnetic field in the usable channel, minimizing losses. Striking the right balance is important while creating a motor with maximum brushless motor torque that does not draw a tremendous amount of power. Understanding the complete motor design allows Portescap engineers to pack the most power possible into the smallest motor package.
Portescap’s Ultra EC™ platform offers 3 families of brushless slotless motors to help you address a wide range of requirements for brushless motor torque and speed. The patented U coil provides outstanding performance, including minimal iron losses, increased efficiency and cooler operation. The key to the outstanding performance of these mini brushless motors is this new coil, designed by Portescap in Switzerland. This unique coil design allows two-pole motors, for example, to deliver 30 % more brushless motor torque compared to the same size motor using a conventional coil design, while substantially lowering iron losses.
BRUSHLESS DC MOTOR TECHNOLOGY: SLOTTED & SLOTLESS
Portescap offers mainly two types of brushless DC motor technologies: slotted and slotless. Both of these brushless DC motors have permanent magnet rotors with 2 or 4 pole pairs. Slotted brushless DC motors have coils inserted in the slots of the stator. Due to these slots, the rotor has preferred equilibrium positions when the motor is unenergized. This resistant torque is called cogging or detent torque. Slotless brushless DC motors have a self-supporting cylindrical coil, creating no detent torque thus the rotor does not have preferred equilibrium positions. Both of these brushless DC motor technologies feature high efficiency, high speed, and hall sensors/sensorless options.
One technology uses a stator that consists of stacked steel lamination with winding placed in the slots that are axially cut along the inner periphery. This is called the BLDC motor, slotted iron structure. The other technology uses a self-supporting cylindrical ironless coil made in the same winding technique as for our ironless rotor DC motors. This is called the BLDC motor, slotless iron structure.
ADVANTAGES OF BRUSHLESS DC MOTORS
PORTESCAP BRUSHLESS DC MOTORS
Portescap Brushless DC motors are extremely reliable and built to deliver the best performances. Their high power density allows a reduction in the overall size of most of the applications. They feature silent running even at high speed. The autoclavable option is ideal for medical applications.
They have a maximum continuous stall torque of up to 39 oz-in (276 mNm). Their peak torque is up to 332.7 oz-in (2’278 mNm). They can achieve speeds of up to 100’000 rpm. Standard diameters range from 0.5 to 2.3 in (12.7 to 58 mm).
Portescap can provide custom motors for your project’s needs. Various stack lengths are available in each frame size. Autoclavable options are available for devices which require sterilization.
Portescap offers custom winding, shaft modification including hollow shaft, and special materials, coating and plating. Lead length, type, color and connector, gearheads, and encoders can be customized.
Most of our BLDC products can be customized or modified with special features that include:
- Special shafts (longer or shorter, larger or smaller diameters, cross holes, axial holes, cannulated, special materials and coatings)
- Special construction for non-medical applications (aluminum housing/end bellws, steel gearhead components, steel bearings)
- Special windings (higher voltage, different speeds)
- Special lead terminations (no connections, special connectors, integral connectors, special colors)
- Special mounting features
- Alternate lam materials
- Alternate magnet materials
- Sterilizable option
- Encoder options
BRUSHLESS DC MOTOR APPLICATIONS
Brushless DC motors are integral to many applications, especially those in the Medical Device, Industrial Automation, Aerospace and Defense, Security and Access, and other industries.
BLDC motors are ideal for high speed surgical and dental hand tools, including small bone and large bone tools and dental tools such as drills. They are also very effective for respirators and ventilators, infusion and insulin pumps, dental imaging, and analyzers.
- High speed surgical hand tools
- Small bone surgical hand tools
- Large bone surgical hand tools
- Dental hand tools
- Respirators & ventilators
- Infusion & insulin pumps
- Dental imaging
- Surgical robotics
- Bionics and Exoskeleton systems
Brushless DC motors are used in industrial nut runners and screwdrivers, air pumps, conveyors, and electronic assembly devices.
- Industrial nut runners
- Industrial screwdrivers
- Air pumps
- Electronic assembly
- Electric grippers
AEROSPACE & DEFENSE
The longevity and reliability of BLDC motors make them a good choice for aircraft on-board instrumentation, gyroscopes, and satellites. They are also commonly used in valves, fuel metering systems and electric actuators.
- Aircraft on board instrumentation
- Fuel metering system
- Electric actuator
- Detection and service robots
SECURITY & ACCESS
The compact size and low running temperatures of Brushless DC motors make them excellent for use in barcode readers, cameras, locks, and ticket printers and dispensers.
- Barcode readers
- Ticket printer & dispenser
Other applications for brushless DC motors are robotics, precision instrumentation, and engraving.
- Precision instrumentation
COMPOSITION AND VARIATIONS OF BRUSHLESS DC (BLDC) MOTORS
|Permanent magnet brushless DC motor design||Essentially linear torque/speed curve (neglecting iron losses), with torque proportional to current and speed proportional to voltage||Ease of speed and position control|
|Brushless Design||Life is not limited by brush wear but only by wear in ball bearings||Very long life, high reliability, insensitive to environment. No arcing, dust free. Reduced audible and electrical noise|
|Autoclavable version||Suitable sealing and optimized design||Withstand autoclaving and sterilization cycles. Sealing prevents contamination|
|Static winding attached to motor housing||Improved heat dissipation||Overload capability|
SLOTTED VS. SLOTLESS BLDC MOTOR TECHNOLOGIES
|Ability to withstand harsh environment / Autoclavability||++||+|
|Torque / Power ratio||++||+|
|High speed capability||+||++|
|Versions without hall sensor||Typically used in spindle applications||Cost effective. Less sensitive to environment. Only three connecting wires|
|Versions with hall sensors||Typically used in applications where speed or load variation are needed||Very simple commutation circuitry|
|Versions with encoder or resolver||Typically used in incremental motion||Very precise speed and position control|
|Version with integrated electronic||Hall sensors and commande circuitry are integrated to the motor||Plug and play configuration|
Can be driven like a brush DC motor
BLDC SLOTTED MOTORS - ADDITIONAL INFORMATION
Brushless DC slotted - Rear end bell and PCB
Brushless DC slotted - Laminations stack
Brushless DC slotted - PCB
Brushless DC slotted - Rotor
Brushless DC slotted - Molded stator