Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

New answers tagged

0

The only reason to continue switching with the motor at standstill is to use the motor as an active brake to prevent external forces from moving the load mechanism. An SVPWM scheme is not likely to be capable of doing that. If the motor is to remain at standstill for hours at a time, it would be good to consider the use of a "sleep" mode which cuts power to ...


1

When MOSFETs switch they dissipate a small amount of power and, because the motor is still loading the output, this power (dynamic switching power) will still be present irrespective of motor speed. There will also be some power dissipated in the motor even though the duty cycle (50%) prevents forward or reverse motion.


1

If you apply 180W to the motor when it is almost stalled (ie too much mechanical load), it will melt the motor. If you apply 180W with no load, the motor will spin so fast that it will damage the device. 180W only applies to the rated torque and rated speed, which has about half of the no load speed and half the 0 rpm torque. I, too, was surprised when I ...


0

It is indeed possible, to do so take a look at the work done in the following paper: Sensorless Adaptive Speed Control for PMSM Drives Within this paper it is explained how to get the flux linkeage. Afterwards it is shown how to estimate this flux variation to estimate the rotor speed:


2

Yes, the voltage and amperage do make a difference. To start with the motor wants to spin at a speed proportional to voltage, so if the voltage is too high or too low the motor will either over-speed or not run fast enough. Over-speeding can produce excessive brush arcing and commutator wear, reduce bearing life, or even cause the armature to fly apart. ...


0

DC motors can draw several times their rated current at startup. As the motor speed comes up, the difference between the emf generated and the supply voltage falls, and so the maximum current also falls. Your BMS is probably responding to that initial current. The device you haven't identified is a bimetallic thermal fuse, they respond both to ambient ...


3

As I read the accepted answer my brain came up with the following simplification, which I think is loosely accurate (?): Motors are both dynamos and electromagnets. Turning a motor invokes its properties as a dynamo. Because the motor's terminals are shorted together, the generated voltage is applied to the motor coil windings, invoking the motor's ...


4

"applying a resistive load" to a running motor is essentially how an electric brake works. As a first approximation, the torque produced by the motor is proportional to the current, that's turning the motor is harder as the load resistance gets smaller. When you short the terminals, there's only the internal resistance of the motor which limits the current.


0

Do you have the C rating and the capacity of the Li-Po battery this will give you how much the current the battery is able to deliver continuously. The buck regulator will cause the current draw to be less on the high side so if it is the over current protection that is stopping you this might be the reason.See this page for introduction You might ...


39

I have to start with some terminology -- sorry if it's esoteric, but this will bring things into line with how folks talk about this subject. When you turn a permanent-magnet DC machine*, the armature generates a voltage internally. This is called the "EMF"** of the armature, or the "back EMF" if the machine is running as a motor. This EMF is always ...


2

Looks like some sort of a fuse....probably a Resettable PTC Fuse. A Resettable PTC Fuse exhibits the same characteristics as you mentioned. (i.e. getting hot and cutting the power to the motor). When current above the threshold current of the fuse flows, the fuse gets hot and stops conducting. The conduction of electricity resumes when high current or ...


3

It makes no difference what it is. It is the component that is protecting the motor from the real problem. The most probable problem is that the motor does not have sufficient power or torque to do the job. There is also the possibility of improper motor use.


3

More turns: higher flux and therefore pulling strength at cost of higher back emf which will drown driving voltage once speed starts to rise. However, to avoid high I^2R heat losses, you may need to use thicker wire (higher volume/weight/cost). Basically, lower RPM means the stator coils will act more resistive than inductive. More rotor pole pairs: closer ...


0

A "brake motor" is usually a motor that has a DC powered brake coil on it that operates to RELEASE a spring powered mechanical brake. In a typical brake motor circuit, the brake coil is powered by the same motor leads that tun the motor. So when you turn on the motor, you are energizing the brake coil simultaneously, releasing the brake. that brake coil is ...


4

I am making a motor and was wondering if it is necessary to use insulated copper wire instead of any regular copper wire. This depends on what you mean by "insulated". In a motor or any device that uses multiple turns to form an inductor - a device that increases the magnetic field by using a single isolated multi-turn conductor, then the current MUST ...


0

So this looks as if the circuit controls armature current? It controls armature voltage. would it be better if the winding current was controlled? Controlling armature current with an outer voltage or speed control loop would be better, but more complex. By "winding current" I suspect you mean field winding current as apposed to armature winding ...


2

Motors have a surge current that depends on acceleration and fans have a steady current that is linear like a resistor. V/I= constant at steady state RPM above start. So the BLDC motors convert DC to AC and the Vdc/motor DCR determines the starting current. But as the fan speeds up backEMF reduces the current. So you have a Buck regulator rated for 80W ...


3

The selected fans have brushless motors with electronic control circuits built in. The motor coils are not powered directly by the input power and should not transmit any inductive kickback to the external supply. However there is no indication that the motors are designed for variable voltage operation.


0

there are dual rated drives but the output voltage is what the input voltage is. that means you would need to change the motor wiring according to the drive supply source negating the convenience of changing voltage input to a static motor.


0

The nameplate is your "goto" for this information. It must tell you the operating voltage range. e.g. This one is "universal".


2

Pardon my ignorance on this application, but I do not know the nature of your load current if that was measured or rated. My understanding is the Load Transfer Switch(LTC) & motor operate in a discontinuous mode of AC start-surge then DC-rapid stop, then idle for <30 seconds in order to regulate the primary grid voltage into the transformer. The ...


0

Could be done with end stops and micro-switches cutting power when it reaches the 90 degrees. As for turning back either have a second button powering the motor in reverse, again, switched off by a micro-switch.


2

For only 90 degrees of rotation, I would consider a push-pull solenoid operating a bell crank mechanism.


1

This is my first attempt at electrical engineering... I am completely ignorant of this field and have tried my best to piece together my understanding of everything i'm working with Engineering is very much about ratings and specifications. You seem to know that you have a 12-volt motor. Is that all you know about it? Where did you get that information? ...


4

Judging from the motor picture, you have a fairly powerful motor RS-550 class, from some power tool/drill or other appliance. The motor start-up current (or load current) is likely above the capability of your power supply, and the supply goes into sporadic shutdown mode, and back. If your power supply is already giving out just 12 V instead of 18V, it ...


0

If the PWM frequency is high enough, the ripple in the current through the motor will only be a few percent, though the voltage you see across the terminals will still be swinging from the supply voltage (less the transistor drop) to the diode drop (which will be negative when measured in the same sense as the supply voltage). Your issue is likely that the ...


0

The simplest method, which you will find in a number of stair-stepper, elliptical and stationary bicycles at the gym is to use an automotive alternator. These have the advantage of a wound field, so it's possible to vary the field current, which will be much lower than the output current, by either changing the voltage applied, or use of PWM from a fixed ...


2

Somethink like that. If you wan't a constant torque controller then you should measure the motor current and adjust PWM duty ratio so that the motor current is equal or less the current setpoint (torque setpoint). simulate this circuit – Schematic created using CircuitLab


4

I take it you don't have any specifications for the motor showing the acceptable voltage range? Absent the spec, I would be nearly certain that the motor itself would perform just fine on 36V. For the motor controller; the ones I'm familar with for these kind of applications are actually current-limited, not power-limited. So, your 36V 1kW controller will ...


2

You could use a generator as a variable load. Use a PWM signal to short circuit the output of the generator. Shorter duty cycle is less load, longer duty cycle is more load. A generator is just a motor whose shaft is turned by an external force.


0

Pulsing/jerking can be a symptom of trying to accelerate too fast. Your pulse rate doesn't seem very fast, but if your inertia is high, you could be marginal and you just got lucky that the one direction worked. Increase your delays and see what happens. If you need to reach a high angular velocity and the inertia won't allow you to instantly go to that ...


0

I can see the problem here . And as i know multiple if else if statement should end with else in the end to tell the arduino if all the statement above is false then else{do this}. if-else-if ladder: Here, a user can decide among multiple options.The if statements are executed from the top down. As soon as one of the conditions controlling the if is true, ...


0

I had a 2.4V shaver that when the batteries failed, rather than replace them, I built a 12V to 3V converter to power it. ( I had also discovered that it worked better at the higher voltage. ) I kept both in the car for several years until the blades got too dull to use. So it should be safe and last as long for you.


0

The voltage for a given dc motor is the nominal or average voltage for it based on n number of hours of operation, number of wire loops in the coil, construction, etc. The operating voltage is actually a range from minimum to turn on, minimum to stay on, and maximum voltage, just like any inductor. You can see the specs if you can find the data sheet from ...


1

It will probably last for ever. Thats not much over and for the short time of a shave. would not worry it the least.


3

If the control circuit power supply also powers electronic control equipment or if the relays are in the same enclosure with electronic control equipment, then every relay should have transient voltage suppression. For AC relay coils, RC suppression should be used. For DC coils, an anti-parallel diode should be used. If the soft starter is electronically ...


2

This is a capacitor start induction motor. Most of the field is generated by the main winding, which in this case looks to be in two sections (to allow it to be series or parallel connected to operate at different voltages). Alone this generates no direction of rotation on a single phase, so there's an additional winding, at 90 degrees electrical, which can ...


Top 50 recent answers are included