Electric Motor

Brushless DC (BLDC) motors are one of the electrical drives that are rapidly

gaining popularity, due to their high efficiency, good dynamic response and low

maintenance. In this paper, the modeling and simulation of the BLDC motor was done

using the software package MATLAB/SIMULINK. A speed controller has been designed

successfully for closed loop operation of the BLDC motor so that the motor runs very

closed to the reference speed. The simulated system has a fast response with small

overshoot and zero steady state error.

http://www.eurojournals.com/ejsr_35_2_05.pdf

It is assumed that the BLDC motor is connected to the output of the inverter, while the inverter input terminals are connected to a constant supply voltage, as shown in Fig.1. Another assumption is that there are no power losses in the inverter and the 3-phase motor winding is connected in star.

http://www.eurojournals.com/ejsr_35_2_05.pdf

The control consists of logic circuitry and a power stage to drive the motor. The control’s logic circuitry is

designed to switch current at the optimum timing point. It receives information about the shaft/magnet

location (signals from the Hall devices), and outputs a signal, to turn on a specific power device, to apply

power from the power supply (not shown) to specific windings of the brushless motor.

http://www.motioncontrolonline.org/files/public/BrushlessOperation.pdf

This application note discusses the steps of developing

several controllers for brushless motors. We cover sensored,

sensorless, open loop, and closed loop design.

There is even a controller with independent voltage and

speed controls so you can discover your motor’s characteristics

empirically.

The code in this application note was developed with

the Microchip PIC16F877 PICmicro® Microcontroller, in

conjuction with the In-Circuit Debugger (ICD). This

combination was chosen because the ICD is inexpensive,

and code can be debugged in the prototype hardware

without need for an extra programmer or

emulator. As the design develops, we program the target

http://www.jimfranklin.info/microchipdatasheets/00857a.pdf

My first speed 300 motor died after about half year of flying. In order to have better performances, I decide to change the engine into brushless. There are several choices of brushless motor in the market, such as the Hacker and Astro. By the way, there has been a mania for using modified CD-Rom motor in our RC models. Needless to say, I have joined the groups that are trying to find out the potential of these wildly available and low-price CD-Rom motors. 

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Video Radio control electric brushless motor winding tutorial  

Tutorial on brushless motor winding presented by Utah Flyers.

Brushless DC Motor COMMUTATION SEQUENCE

Figure shows an example of Hall sensor signals with

respect to back EMF and the phase current. Figure 8

shows the switching sequence that should be followed

with respect to the Hall sensors. The sequence numbers

on Figure correspond to the numbers given in Figure 8.

Every 60 electrical degrees of rotation, one of the Hall

sensors changes the state. Given this, it takes six steps

to complete an electrical cycle. In synchronous, with

every 60 electrical degrees, the phase current switching

should be updated. However, one electrical cycle

may not correspond to a complete mechanical revolution

of the rotor. The number of electrical cycles to be

repeated to complete a mechanical rotation is determined

by the rotor pole pairs. For each rotor pole pairs,

one electrical cycle is completed. So, the number of

electrical cycles/rotations equals the rotor pole pairs.

Figure is a graphical representation of the BEMF formulas

computed over one electrical revolution. To

avoid clutter, only the terminal A waveform, as would

be observed on a oscilloscope is displayed and is

denoted as BEMF(drive on). The terminal A waveform

is flattened at the top and bottom because at those

points the terminal is connected to the drive voltage or

ground. The sinusoidal waveforms are the individual

coil BEMFs relative to the coil common connection

point. The 60 degree sinusoidal humps are the BEMFs

of the driven coil pairs relative to ground. The entire

graph has been normalized to the RMS value of the coil

pair BEMFs.

Notice that the BEMF(drive on) waveform is fairly linear

and passes through a voltage that is exactly half of the

applied voltage at precisely 60 degrees which coincides

with the zero crossing of the coil A BEMF waveform.

This implies that we can determine the rotor

electrical position by detecting when the open terminal

voltage equals half the applied voltage.

The fact that one of the windings is not energized during each sector is an important characteristic of six-step control that allows for the use of a sensorless control algorithm. When a BLDC motor rotates, each winding generates BEMF, which opposes the main voltage supplied to the windings according to Lenz’s Law. The polarity of this BEMF is in the opposite direction of the energizing voltage. Figure 2, below, shows ideal BEMF waveforms and the zero-crossing points.

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E-flite EFLA311, 20 A ESC driving an E-flite 450 motor.

Video how to take off brushless dc motor

Video how to clean brushless dc motor

Video how to assemble brushless dc motor

 

CONSTRUCTION AND OPERATING PRINCIPLE

BLDC motors are a type of synchronous motor. This

means the magnetic field generated by the stator and

the magnetic field generated by the rotor rotate at the

same frequency. BLDC motors do not experience the

“slip” that is normally seen in induction motors.

BLDC motors come in single-phase, 2-phase and

3-phase configurations. Corresponding to its type, the

stator has the same number of windings. Out of these,

3-phase motors are the most popular and widely used.

This application note focuses on 3-phase motors.

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The construction of modern brushless motors is very similar to the ac motor, known as the permanent magnet synchronous motor. Fig.1 illustrates the structure of a typical three-phase brushless dc motor. The stator windings are similar to those in a polyphase ac motor, and the rotor is composed of one or more permanent magnets. Brushless dc motors are different from ac synchronous motors in that the former incorporates some means to detect the rotor position (or magnetic poles) to produce signals to control the electronic switches as shown in Fig.2. The most common position/pole sensor is the Hall element, but some motors use optical sensors.

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Machining A Brushless Motor with a lathe and drill press. Just a quick slide show of some motor contsruction tips before I added a small milling machine to my hobby shop. John  

A picture is worth hundreds of words. Here is a wiring diagram for the star configuration that I have found from the net. you are better to do this with great circumspection or it would be easily end up with a burned ESC. The first photo shown above is one group of the windings on the stator. Two groups are wound in the second photo while all three groups are wound in the last photo. The starts of each three groups are soldered together and the three ends are the phase wires that connect to the brushless controller.

The 'standard' Star diagram for

9-tooth stators & 12 magnets

more

Radio control electric brushless motor winding tutorial video

Tutorial on brushless motor winding video presented by Utah Flyers. 

Video of a Home Built Brushless DC Motor

Three students (16-17 years old) from the "Stedelijk College" in Eindhoven, the Netherlands designed and made this motor in one day! The motor turns with approximately 2000 rpm!

This is my homemade brushless motor. Or you could call it a fan! It's made from old junk and surplus components mostly. Better description is in the video!

Video home made brushless dc motor battery: Align 3 cell li-po 11.1v Reed switch 8 neodymium magnets no bearings were used (performance would have improved greatly if bearings were used on the spindle)

However, if, at the appropriate time, current is shut off in winding “R”, and turned on in winding “S”, then the rotor continues to move. Again at the appropriate time, shut off “S” and turned on “T”. By continuation of this timing sequence, complete rotation occurs. What is occurring, is that the field set up by the stator is being switched, and the rotor tries to catch up to it.

In this example, the explanation was simplified by exciting only one winding at a time. In reality, the stator consists of a three phase Y–connected winding, and two or three windings are actually energized.. This makes efficient use of windings and development of higher motor torques.

In its simplest form, a brushless dc motor consists of a permanent magnet, which rotates (the rotor), surrounded by three equally spaced windings, which are fixed (the stator). Current flow in each winding produces a magnetic field vector, which sums with the fields from the other windings. By controlling currents in the three windings, a magnetic field of arbitrary direction and magnitude can be produced by the stator. Torque is then produced by the attraction or repulsion between this net stator field and the magnetic field of the rotor.

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Conventional dc motors are highly efficient and their characteristics make them suitable for use as servomotors. However, their only drawback is that they need a commutator and brushes which are subject to wear and require maintenance. When the functions of commutator and brushes were implemented by solid-state switches, maintenance-free motors were realised. These motors are now known as brushless dc motors. In this chapter, the basic structures, drive circuits, fundamental principles, steady state characteristics, and applications of brushless dc motors will be discussed.
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This application note discusses how to use the

Enhanced, Capture, Compare, PWM (ECCP) on the

PIC16F684 Microcontroller for bidirectional, brushed DC (BDC) motor

control. Low-cost brushed DC motor control can be

used in applications such as intelligent toys, small

appliances and power tools. The PIC16F684 takes

Microchip's Mid-Range Family of products to the next

level with its new ECCP peripheral. The ECCP

peripheral builds on the technology of the CCP module

with added features such as four PWM channels for

easy bidirectional motor control through the hardware.

This application note focuses on using the ECCP in

PWM mode using the full-bridge configuration. Using

the ECCP allows easy interfacing to a full-bridge

configuration for bidirectional BDC motor control.

I used PIC microcontroller to realize the control of BLDC motor. In the video, you can observe how the PID parameter affect the performance of motor. The different magnitudes (due to different PID parameters)

Efficient Brushless DC motor and Permanent Magnet Synchronous Motor Control

Demonstration of advanced sensorless algorithms such as field oriented control and trapezoidal control using sinusoidal drive for Brushless DC (BLDC) and Permanent Magnet (PM) Synchronous Motors

BLDC motors can be designed to operate from a high voltage or low voltage source. The following seminar explores BLDC control using PIC18F Microcontroller devices.

This application note discusses the closed loop control of a 3-Phase Brushless

Direct Current (BLDC) motor using the Z8 Encore! MC™ Family of

Microcontrollers series microcontrollers (MCUs). The Z8 Encore! MC™ product

family is designed specifically for motor control applications, featuring an on-chip

integrated array of application-specific analog and digital modules. This in turn

results in fast and precise fault control, high system efficiency, and “on-the-fly”

speed / torque and direction control, as well as ease of firmware development for

customized applications.

This article further discusses ways on how to implement a sensorless feedback

control system using a “Phase Locked Loop” along with Back EMF sensing.

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This application note describes how to implement sensorless commutation control

of a 3-phase brushless DC  motor (BLDC) with the low cost ATmega48

microcontroller. A general solution, suitable for most 3-phase BLDC motors on the

market is presented. The full source code is written in the C language, no assembly

is required. Adaptation to different motors is done through the setting of parameters

in the source code.

The ATmega48/88/168 devices are all pin and source code compatible. The only

difference is memory sizes. This application note is written with ATmega48 in mind,

but any reference to ATmega48 in this document also applies to ATmega88/168.

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This application note demonstrates the use of a low cost NXP Semiconductors LPC2101 microcontroller for bidirectional brushed DC motor control.

The LPC2101 is based on a 16/32-bit ARM7 CPU combined with embedded high-speed flash memory. A superior performance as well as their tiny size, low power consumption and a blend of on-chip peripherals make these devices ideal for a wide range of applications. Various 32-bit and 16-bit timers, 10-bit ADC and PWM features through output match on all timers, make them particularly suitable for industrial control. 

Brushed DC (Direct Current) motors are most commonly used in easy to drive, variable speed and high start-up torque applications. They have become widespread and are available in all shapes and sizes from large-scale industrial models to small motors for light applications (such as 12 V DC motors).

This application note describes the design of a 3-phase

sensorless BLDC motor drive with Back-EMF

zero crossing. It is based on Freescale’s MC9S08AC16

that can be effectively used for motor-control

applications.

The concept of the application is that of a speed-closed

loop drive using Back-EMF zero crossing technique for

positional detection. It serves as an example of a

sensorless BLDC motor control system using

Freescale’s MCU and 3-Phase BLDC/PMSM

Low-Voltage Motor Control Drive. It also illustrates

the usage of general on-chip peripherals for

motor-control applications.

This application note includes a description of the

controller features, basic BLDC motor theory, system

design concept, hardware implementation, software

design including the FreeMaster software visualization

tool, application setup, and demo operation.

There is a lot of interest in using Brushless DC (BLDC)

motors. Among the many advantages to a BLDC motor

over a brushed DC motor, we can enumerate the

following:

• The absence of the mechanical commutator

allows higher speeds

• Brush performance limits the transient response

in the DC motor

• With the DC motor you have to add the voltage

drop in the brushes among motor losses

• Brush restrictions on reactance voltage of the

armature constrains the length of core reducing

the speed response and increasing the inertia for

a specific torque

• The source of heating in the BLDC motor is in the

stator, while in the DC motor it is in the rotor,

therefore it is easier to dissipate heat in the BLDC

• Reduced audible and electromagnetic noise

Brushless DC Motors Theory and Driver Circuit

Buy Brushless  Motor  Speed Controller