# Questions tagged [brushless-dc-motor]

A brushless DC electric motor is a DC motor type that uses an electronic inverter/switching circuit to energize the motor coils in a sequence (based on the detected rotor position) in order to rotate the motor.

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### Brushless motor dynamics (BLDC transfer function)?

I am building a quadrotor and want get a reasonable estimate of the dynamics (voltage to rpm transfer function) of the motors. I am wondering: 1) Is the transfer function for a typical BLDC 1st or ...
240k views

### How are current and voltage related to torque and speed of a brushless motor?

I know that electric vehicles have different performances depending on battery and motor, but it's not clear how electrical and mechanical units are related. Can anybody please help? Will a 100V ...
3k views

### Which of the following motors best suit as a wind generator? [closed]

I'm watching some brushless outrunners with low kv as a generator for a simple wind turbine that I'm going to build soon. It might not be a scale or fully useful turbine, because I want to build it ...
19k views

### Calculating Back EMF from Torque Constant

I have a brushless DC motor with a torque constant of .0181 Nm/A. How do I calculate back emf (Vpeak/kRPM) from torque constant (Nm/A)?
2k views

### BLDC BEMF not right

I am trying to build my own ESC (brushless DC controller) and I managed to get the motor running starting from a ramp to a steady PWM duty Cycle and Commutation period and these are the BEMF waveforms ...
64k views

### Understanding motor constants Kt and Kemf for comparing brushless DC motors

So for a practical definition, the torque constant Kt specifies how many Nm of torque you'll get from the motor at a certain current? Is a bigger Kt always better? I am more confused about the ...
32k views

### Control differences between ac induction motor and brushless dc motor?

I have a fairly solid background in industrial AC motor control (soft starters, VFDs, etc.) but something that I'm certainly NOT well versed in is brushless DC motors... the type found in every hard ...
4k views

### How to use an ESC

I'm new to RC related modules. Today I got my Hobbywing's Skywalker 20A brushless esc. Manual is here. I also have a brushless outrunner motor (HL3512) I don't ...
6k views

### Controlling small brushless dc motors?

I'm designing an ESC with a small microcontroller running at 3.3V. The BLDC motors I have chosen are extremely small, and run best at 3.7V. I have the power supply for both of these (3.7V is VBATT, 3....
409 views

### voltage divider — for detecting higher voltage in ADC

I am working on a BLDC sensorless motor. I need to detect BEMF Zero-cross event. My Motor is working on 24 Volt power. Now I need to detect the back E.M.F. As refered in this application note. My ...
1k views

### BLDC Motor Constants: Why is my Kt and Ke different?

I'm new to working with motors. Reading up on BLDC theory, it is repeatedly said that in SI units, the Ke and Kt will be numerically equal. I downloaded the motor spec excel sheet of the T1101 motor ...
7k views

### Why do brushless motors have a kv rating?

I am wondering why brushless motors, such as ones used for quadrotors, have a kv rating, which supposedly means RPM per voltage across the motor. So a 2300 kv motor spins at 2300 rpm if "1 volt is ...
59k views

### Difference between Brushless Motor and Stepper Motor

I think I understand the operating principles of a brushless motor and a stepper motor, but I'm a little confused about the difference. Is a brushless DC motor a very basic stepper motor? With ...
63k views

### How to drive brushless motor with Arduino?

Is it possible to drive a brushless motor directly with Arduino? Or should I revert on controlling a brushless motor ESC with PWM pulses?
164 views

### How to measure DC motor (used as generator) efficiency using homebrew methods?

Background I'll be making a "micro thermal power station" in the single-digit watt range at home (one-off, educational project. Bear with me). A heat source, likely ethanol, will cause a stirling ...
4k views

### Why Have Non-Zero Timing on a BLDC?

I've heard you can go faster in one direction if you adjust the timing, but do not understand why? I have a sensored bldc motor with a 30deg shift of the hall-effect sensors, tried going forward (CCW ...
9k views

### Which voltage uses the “Kv” parameter in a BLDC (Brushless DC) motor?

According to the definition of a BLDC by Wikipedia: $K_V$ is the motor velocity constant, measured in RPM per Volt (not to be confused with "kV," the abbreviation for "kilovolt")[6]. The $K_V$...
3k views

### How do you read newer HDD motors (DC/Brushless) into arduino? (like stepper motors)

We had a version of the HDDJ working with an arduino reading an old stepper motor (with 4 wires), then sending serial data to processing, using a midi library, and midiox + midiyoke. Having trouble ...
6k views

### Cannibalizing a printer, how to figure out what some of the parts are/do

My son an I are attempting to cannibalize a printer a HP LaserJet 1300. It used to work and print, but it was low on toner and the company we got it from replaced it instead of buying new toner. So, ...
3k views

### Sensing BLDC motor torque using a current sensor

As it is commonly known, the torque supplied by a motor is directly proportional to the current it draws. So when a motor is under heavy load, the torque required will be more hence it would draw more ...
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### Does increasing voltage increase the torque of a brushless motor?

1.) I have a brushless motor with testing data at 12V. I want to know if I increase the voltage supply, will this increase the torque? In my research I keep seeing "current controls torque, and ...
46 views

### Determine efficiency, voltage, current from motor characteristic curves

I would to identify efficiency, voltage, current for a particular Brush less DC motor in our lab given characteristic curves. Electrical specifications are The operating conditions are ...
460 views

### dc brushless motor specs for generator

Hello i have done my research and have found varying information relating to the speed at which you must drive a motor to get a desired output and that it is dependent upon back EMF however i am very ...
1k views

### Need help with the BLDC drive inverter circuit problem

I am building a BLDC drive circuit for a 24V/60W BLDC motor. I chose SI4564DY(P+N) and FAN3278 to realize it as shown below (I only include A+ and A-, B and C are exactly the same). The FB indicated ...
14k views

### Can ANY DC brushless motor be used as a generator?

Question is pretty much in the title. I know it's definitely possible to use certain DC brushless motor as a generator, but is it always the case? Thanks a lot in advance.
1k views

### Brushless DC motor problems at high velocities

For a project we use a brushless DC (BLDC) motor. Everything works fine until we tried to reach high velocities. I will first explain my setup, and than explain our problems using some graphs. ...
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### How to use a salvaged brushless motor

I recently took apart an HP LaserJet 1320 laser printer to salvage parts from it. Along with 3 solenoids, a fan, lots of gears, 83 springs, and 71 feet of wire, I got a large brushless DC motor with ...
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### For Brushless DC Motors would one expect harmonics to be different between Delta and Y stator windings?

Given two 3-phase brushless DC motors with the only difference being that one is wound delta, the other Y with center grounded, would I expect to see high frequency voltage-current harmonics to be ...
1k views

### Braking by short circuiting possible? [closed]

If I short the three terminals of a bldc motor after switching off the supply to the motor, will that give me braking? And if it can how can I implement this? I'm working on a project called ...
120 views

### Problems with dc motor driver design: Mosfet fail

I made a brushed dc motor driver. The motor speed is controlled with PWM (from an Arduino). The motor that I'm using draws 3 amps without load. This is the schematic: As you can see there are two N ...
253 views

### Help understanding the code

I am new to C programming. I need your help in understanding the some particular lines in a code segment for sensored control of a brushless dc motor. It was written for a 16-bit MCU (dsPIC33FJ32MC710)...
1k views

### A strange problem in BLDC motor drive: PWM frequency and duty cycle go wired

I am working on a BLDC motor controller to drive a 2kW BLDC motor with six-step control. The design has two board, one MCU board and one interver board, and the picture below shows one phase drive ...
315 views

### Mechanical time constant of PMDC Motor in starting and after switching off the supply is same or different?

In my MATLAB/SIMULINK model of the PMDC motor the mechanical time constant has same value in the case starting of motor and after switching off the supply but in experimental setup there is a ...
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### Extra Shottky Flyback Diodes on FET-based BLDC Motor Driver? [duplicate]

TL;DR: I have a FET-based BLDC motor driver design, and I need to decide whether to add discrete Shottky diodes in parallel with each FET for reliable and long-lived operation in an automotive-like ...
1k views

### How to realize constant acceleration control for BLDC motor?

I would like to realize a constant acceleration control of BLDC motor so that its speed can rise from zero to target speed in a predefined time period. I understand that the motor should be able to ...
2k views

### BLDC speed and torque control

I have a question understanding the exact commutation of the sensorless BLDC motors. My motor has 7 pole pairs. Now assuming the 3 phases are - U,V and W ( so that's U+,U-,V+,V-,W+ and W- from the ...
350 views

### BLDC Current Driver Encountering Current Problems

The attached Schematic uses 6 N Channel Power Mosfets "IRL3303". I have wound my inrunner bldc motor with 180 windings per phase using a 26 Gauge Magnetic Wire. My motor is a 6 pole 2 magnets machine. ...
251 views

### Can I drive a BLDC driver with this diagram?

I'm a programmer and I've only started messing with hardware half a year ago, mainly with the Raspberry Pi. I now want to drive a brushless DC motor using my Raspberry pi. To do this, I've bought this ...
759 views

### What kind of DC motor is this and what does the circuit do?

I've had this motor at least for 5 years (salvaged from something) and I remember it working then. However it doesn't work now (5 VDC mobile charger) and so I opened it up expecting to see just the ...
99 views

### Brushed motor VS BLDC [closed]

Our brushed DC motor is rated for 3-4 amps and can be overloaded for 8+ amps. We are currently changing the brushed motor for a brushless (BLDC) motor, rated at 3.5 amps. How much can I overload the ...