New answers tagged

0

most of the torque that the motor imposes on the axle itself due to things like motor frictional losses, induced eddy currents, etc. Motor frictional losses and aerodynamic drag (windage) are the only losses that the motor imposes on the motor shaft (axle). All of the other losses convert input electrical power to heat, subtracting from the percent of ...


3

The simplest solution is to use a coreless or 'ironless' motor. With good bearings the drag at low speed should be be very low. Brushed coreless motors also have the advantage of very low inertia. As an example of how free a coreless motor can be, the ironless brushless motor below can be used as a compass! The rotor spins so freely that - with no iron to ...


1

How battery voltage discharge can affect motor current measurement depending on the same load... Does it will affect my current reading and the current will increase? Torque is directly proportional to current, independent of battery voltage. Could I sense the BLDC motor current directly on the battery high side or do I need to sense it on all ...


0

A couple of background notes to hopefully help your thinking. In six step commutation with PWM speed control, the effective applied voltage to the motor, V_APPLIED is: V_APPLIED = VBATT * D where D is the duty cycle. The resulting phase current, I_PHASE will be: I_PHASE = (V_APPLIED - V_BACK) / R_PHASE where R_PHASE is the phase-to-phase resistance and ...


0

I guess I can sort of answer your questions. battery discharge usually relates to voltage drop, so with a lower voltage the current will have to increase to deliver exactly the same torque. Before discussing what you can measure I think you need to decide a control scheme for the motor. This is an example of a scheme, to answer your question you need to be ...


0

Why would 150Kv 5ohm motor have more torque than 87Kv 6.5ohm? As your research showed, Kt (torque constant) is the inverse of Kv (velocity constant). Therefore a 150Kv motor should have 150/87 = 1.72 times less torque than an 87kV motor at the same current. However at 5 Ω vs 6.5 Ω it should draw 6.5/5 = 1.3 times more current at stall, so at the ...


0

Basically, if you have a motor that is the right size, physically and power-wise, but you want to optimize it to put out more torque at lower speeds, you would rewind the stator with more turns of smaller diameter wire. This would lower the Kv of the motor. The stator resistance will go up also (longer and narrower wire will have more resistance). In a ...


0

150Kv means 150 rpm/V. 87Kv means 87 rpm/v . It's a voltage constant of electric motor. The torque constant Kt[Nm/A], is also important , it tells you how many torque the motor will output for certain amount of current. These two constants (voltage and torque), like mentioned here in this answer, with their respective units, are inversely proportional. ...


1

Why would 150Kv 5ohm motor have more torque than 87kV 6.5ohm? Well, the 87Kv motor has got more resistance, and, for a given supply voltage, the current must be less than the 5 ohm version and therefore, the torque would be naturally less. Torque is proportional to current taken. More torque means more current taken. Measure the current and then compare ...


1

The best way is by using a H bridge , however if you would like to use only two relays, check the simple attached diagram : Relay one ON, Two OFF: IE Motor runs clockwise Relay one Off, Two ON: Motor will run anticlockwise Both are OFF: no spinning.


3

I suggest: simulate this circuit – Schematic created using CircuitLab With both relays off or both on, both motor terminals are connected to the same voltage, so the motor doesn't run. Operate either relay to connect its end of the motor to the other voltage to make the motor run in the desired direction.


2

Your problem is not just inrush but turn-off arc quench melting plastic from dry contacts reaching >20kV then arcing in < 1us. Motor = 2kW @ 220Vac 50Hz Mechanical switch: two issues contact bounce turning on with 5x inrush while speed up, arc power contact arc turning off with full RPM back EMF and inertia time. Inrush= 500% typical of rated current,...


0

Reduce the voltage. eg: connect it to 110V instead of to 220V It's a fan motor it's designed to drive a speed-dependent load and run at reduced speed by slipping, reducing the supply voltage will increase the slip and reduce the speed without causing any damage.


0

It depends on the driver. Sometimes the driver provides a holding current that is lower than the drive current, to help ensure the motor doesn't move when you don't want it to. Yes, the 6 step type is limited to 6 steps. It can't create more than that because this is saying the driver is only capable of supplying 6 different voltages. More goes into it ...


2

The use of the [inrush-current] tag and the wording of the question seems to imply an assumption that the purpose of the capacitor is to reduce inrush current. That is not correct. The capacitor provides a phase shift of the auxiliary winding current. That phase shift increases the torque capability of the motor in the starting and acceleration part of the ...


5

Your original capacitor has a capacitance of between 50 microfarad and 60 microfarad (sometimes abbreviated confusingly to MFD): - Your microwave capacitors are 0.95 uF and 0.76 uF respectively rendering them useless as a replacement for the original motor start capacitor. Here's a link to Amazon where you can get a GENIE garage door opener replacement ...


1

BLDCs are a type of PM (permanent magnet) synchronous motors, as are AC synchronous motors without brushes. They are very, very, similar. A BLDC always has armature magnets and not armature windings. AC synchronous motors have a field winding and can have armature windings or armature magnets. Having armature windings requires brushes though and you asked ...


0

The PWM you send the servo motor isn't the same as the PWM you send the motor itself. The one you send is just a command signal. It could just as easily be an analog signal voltage or serial message. The actual drive signal containing power which is sent to the internal motor can do whatever it wants. Electronics in between can change it to reverse ...


2

You might need to make a distinction between 'power' PWM, and 'signal' PWM. To command a typical servo, we use a PWM signal which has a high pulse of 1mS full left, 1.5mS centre, 2mS full right, which most servoes will handle being repeated at somewhere between 20Hz and 100Hz. These times are interpretted by the control electronics as a position, and the ...


2

Most small servos don't use magnetic fields for position sensing, they use potentiometers. Here's a good beginner's level explanation in text with a video link. They all seem to have the same basic components – a potentiometer hooked to a voltage regulator and one shot generator, which converts position of the armature to a PWM pulse. This PWM pulse is ...


0

A possibly simpler method is as follows: Set the motor up with a wheel which engages a microswitch (or similar) Wire the microswitch as SW1, the starting switch as SW2: With SW2 unpressed, the motor will go until the tab engages the microswitch, breaking the normally-closed side. It stays there until you press the start switch SW2 for long enough to move ...


1

Yes. You can relatively easily do this: the first momentary switch turns on a relay, which is normally off, and is parallel to that switch. So, turning on the current through the relay's coil makes the relay stay on (we call that a "latch"): simulate this circuit – Schematic created using CircuitLab To turn the motor off, you need to turn the current ...


1

But in my circuit, high output of NCP5104 (half bridge driver) is active in dead time zone. How can I solve it ? Look at "PHASE" voltage - it also goes high by the amount that "Driver high out" goes high. This means that MOSFET Q18 has the same voltage on the gate as the source hence, MOSFET Q18 is actually off (despite your protestations). What you are ...


2

The canonical realization is what's in the picture: three coils for every two magnets. In this canonical realization, the magnets and coils are arranged so that the effect of each one varies in strength sinusoidally. In the circular case, in theory, the two magnets set up a field that is constant and pointing in one direction with respect to the rotor. ...


0

I agree . The best torque increase & RPM reduction is to use belt, pulley, or chain drive. This is a common 1~2kW exercise motor and a human can do 40~100W. So with an efficient mechanism , you ought to be able to reduce RPM with a DC-DC 30A speed controller. If you had any thoughts of using this as a Power generator you are on the wrong track and need ...


1

Hm, no. That motor was designed for exactly the shape of magnet used. You'll practically have no chance replacing that with something stronger. Then you'll change the cabling, i.e. you'll rip out all the hard-lacquered copper and wind something new. Which requires you to get a different cutout to hold your coils. At that point, you're not replacing ...


-1

Since I am using 5V to power motor and arduino also outputs 5V from its pins can I skip IR2104S gate drivers? 4.3V should be enough motor voltage. Yes. 6 mosfets bridge take up a lot of space. Is there an IC that provide same functionality? As stated before the motor should only need about 10W. The motor has phase resistance of 7.5Ω so it ...


1

The current in Stepper motors is constant when static and is defined by the DC resistance. I=V/DCR. The motor will generate voltage according to the velocity you turn it at so the current may rise and fall with velocity but not much as the BEMF is not likely to approach the Vdc EMF applied to each phase coil. When powered off turning the stepper can create ...


2

No, it won't cause any damage, at least in non-pathological cases where you're not exceeding some shaft or drive train mechanical limits and are applying a torque directly to the stepper shaft. A similar thing happens when you try to accelerate too fast and the motor loses steps. Nasty sound but not really a problem for the motor. The coil current is set ...


0

A hidden issue with your project is the kind of brushless motor controller you select. In particular, it seems to me that a good follow-focus system should have precise position control. This is pretty much impossible to achieve with your standard off-the shelf sensorless brushless motor ESC, because sensorless control methods don't work at low speed, and to ...


0

The first rule of experienced engineers -- find something that works and shamelessly copy. There are a lot of micro RC planes out there that use 10W or less, and are powered by 3.7V (one LiPo cell). Some run brushless. So see if you can find an ESC (or an integrated receiver/ESC -- look to Specktrum). Alternately, if you use small complimentary FETs (N- ...


-1

Have a look onto the datasheet of the arduino and check the maximum current sourcing from I/O, it might be enough or not?? But it's definitely not a proper design solution! No one want to see a design like that! If you want to ride of the driver, use a charge pump, the current to turn on the Mosfet will be supplied by the external 5V through the Capacitor.


0

You will not be able to supply the motor with just the GPIO pins of the MCU because the 10W power requirement is too large for the GPIO's to handle. So you will need 6 FETs. you cannot drive 6 Fets without a gate driver to supply the proper voltage. What I suggest is that you use a motor driver that has integrated FETs and gate driver. DRV10970(http://www....


0

two theory: the motor requires a high starting torque because of the motor load. See if you can start the motor without a load or apply a higher CTL signal at startup. The hall sensors are not correctly aligned with what the motor driver expects, check the "Timing chart" in the datasheet vs the motor's datasheet.


1

Lab power supplies generally have a constant current limit, so if a motor tries to draw more the supply will simply lower its output voltage to keep current down to the limit. This is different from switch-mode supplies used in computers etc., which usually cut off completely or 'fold back' to a very low current upon detecting a 'short circuit'. How much ...


-2

Say that the motor is spinning a flywheel.. When the power is turned off the diod bleeds back the energy back thru the coils of the motor to short out or cancel out generated electricity.


3

In answer to your questions, while the circuit will work without the diode, its purpose is to protect the delicate electronic components from very high voltage surges coming from the motor when it shuts off. You see, the windings of the motor act, not only as an electromagnet, but also as an inductor, which stores a great deal of energy in its magnetic field....


0

It should be possible to use 3 hall cell magnetic field detectors to provide commutation sensing. There are numerous IC's that accept 3 hall inputs and provide motor drive signals. Which is most appropriate depends on the alternator / motor ratings. eg the controllers in "hover boards" usually use 3 hall sensors and will drive motors in the hundreds of ...


8

As a slight aside, I thought I should amplify Tony Stewart's comment. The circuit you're looking at is perfectly fine in principle, but it cannot be used for any but the smallest motors. Put it this way - in order to get much current (and therefor much torque or power) from the motor, you need the voltage to be as close to 5 volts as possible. This means ...


16

To understand this trick, a beginner needs to imagine what the voltages are (magnitude and polarity), and where the currents flow (direction and path). I know this from my personal experience; that is why, I have visualized these invisible electrical quantities in the pictures below by voltage bars (in red) and current loops (in green). I have considered the ...


0

I know it's a bit late, but the PBSS5320T,215 pnp super beta transistor has a min HFE of 200 at 1A and it's a 20V part. It would only need 5ma of drive for a full 1A drive.


40

The diode in this configuration is called a "flyback" diode. A motor consists of a coil of wire which is effectively an inductor (and an electromagnet). As the motor spins, the coil will be turned on and off with the commutator inside the motor which will cause voltage spikes. The diode provides a path for this energy so that it can be dissipated into the +...


1

What would generate more power more wrapping of the coils or thicker wire? Is it based on total mass? In general the more 'copper' (wire) and/or 'iron' (magnetic material) a generator has the more power it can produce. But deriving an exact formula is much more difficult than just weighing it. The more efficient the generator is the more power it can ...


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