A DC motor is any of a class of rotary electrical motors that converts direct current electrical energy into mechanical energy. The most common types rely on the forces produced by magnetic fields. Nearly all types of DC motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current in part of the motor.
DC motors were the first form of motor widely used, as they could be powered from existing direct-current lighting power distribution systems. A DC motor's speed can be controlled over a wide range, using either a variable supply voltage or by changing the strength of current in its field windings. Small DC motors are used in tools, toys, and appliances. The universal motor can operate on direct current but is a lightweight brushed motor used for portable power tools and appliances. Larger DC motors are currently used in propulsion of electric vehicles, elevator and hoists, and in drives for steel rolling mills. The advent of power electronics has made replacement of DC motors with AC motors possible in many applications.
So I am doing an experiement about DC motors, and I would like to know why the efficiency plot looks like a parabola. What is the structure behind that. Thank you in advance
Hi Physics! And again, thanks for the membership!
I’m about to build a robot just with some old parts I have. The main thing is the motors. I have 2 DC Motors
Specs below. (It’s a MFA975D Series with gear ratio 49:1)
Operation range(Voltage): 12V
No load = 147RPM
Nm = 1,8
Stall Torque =...
What are the negative effects (if any) of running a compound DC motor with the series field open? I’m troubleshooting a 100hp recoiler motor on a metal slitter machine that constantly blows line and load fuses. It is on a DC drive. The drive has been replaced and the motor has been rewound.
The...
Hello,
I have two designs of DC motors.
Which one is more efficient? I believe what is in question is the location of the communicator. Whether it should be closer to the out piece of the shaft turning the gears? Or should it be further away towards the end? Does this make a difference...
My project is to create a circuit for a stroller that can store the mechanical work into electrical while moving around and with the push of a switch, use the electrically stored energy to assist the movement of the stroller. I’ve tried capacitors but it ended up not being enough voltage and I...
Hello everyone.
I have a RC helicopter (WLtoys V912) that recently had a crash. The main board was damaged and replaced and I got it working again but there is a problem. The main brushless motor is not as powerful as before and I have to apply 75% throttle to keep hovering above the ground. It...
Hello all!
I just discovered PF as I have been searching about a project I have been pondering for a day. The idea is to have a device that I can set my 3lb camera and have the device rotate left-to-right && || right-to-left over the duration of 2 hours for use in a sunset/cloud timelapse...
I need a 12v DC with appropriate torque. In my design, the axle of the motor would be pointed straight in the air and I want to affix a wheel to it and have the wheel spin flat, sort of like a pottery wheel sort of design. I know what the wheel is made of, its dimensions and approximate weight...
Hi, now I'm working on a project which involves a dc motor and high voltage. I'm developing a machine consists of a motor to rotate a platform disc and high voltage will be applied during the rotation. The problem is when I supply a positive high voltage at motor shaft during rotation, the motor...
Hi guys, can someone please have a look at the following problem that I am struggling with;
An 8.25 kW shunt DC motor is supplied with a terminal DC voltage of 300 V. The armature resistance of the motor Ra is 0.25 ohms, and the field resistance Rf is 40 ohms. The field winding consists of 1500...
I am making a small wind turbine for my A-level RMT and wondering what kind of generator I need to charge a 12volt battery. The turbine is a vertical axis savonius turbine that will probably be about a meter high and half a meter wide. I know I can use permanent magnet dc motors and someone...
Hi everyone - here's a concept that I'd like a few opinions on:
As part of a project, I'm looking at using a brushless DC motor mounted on a high-speed vehicle as a generator. Once the vehicle hits its top speed, the batteries should disconnect from the motor and the vehicle's own velocity will...
Homework Statement
Control systems subject. Have a DC motor setup on a difference op-amp, then with gain, and the axel moves a wiper on a pot used for feedback.
I understand the concepts reasonably well enough to complete the assignment.
I'm using MATLAB scripts to approximate parameters...
Homework Statement
I am asked in a lab report to explain the conservation of power in the armature circuit of the DC motor.
Homework Equations
This is the data I have acquired:
The Attempt at a Solution
I have been reading around, and I have learned somewhat about the Armature Copper Loss...
Hi in every theoretical explanation of any kind of DC motor there's always a split ring commutator and two brushes like in the following pic
then when it comes to my motorbike/car starter motor rebuild the real thing in practice is different- see the following pic with four carbon brushes- two...
Today a professor of mine who teaches Electrical machines told us that a DC series motor should not be started without load. I wonder why is that so. Please provide a detailed explanation of this PF members. Thank you very much in advance.
Homework Statement
A 180V separately excited DC motor has an armature resistance of 1.2ohm. When the note runs at 1200rpm,t he armature current is 10A.
1) Assuming that motor torque is constant at all speeds,d determine the mechanical torque and power developed in the motor.
2)Find the speed of...
An 8.25 kW shunt DC motor is supplied with a terminal DC voltage of 300 V. The armature resistance of the motor Ra is 0.25 , and the field resistance Rf is 40 . The field winding consists of 1500 turns. An adjustable resistance Radj is connected in series to the field winding. Radj may be...
So I'm working on a senior design project and was trying to use a DC motor to charge a battery. The point is to allow for quick use to charge a phone or a laptop in circumstances where you need a quick charge. We have lead-acid batteries connected in series and parallel to give us:
14,000mAh...
Hello all,
I'm building a miniature vehicle and plan on using a DC motor that supposedly spins at 12800 rpm (1340 rad/s) for the engine. However, I'm a little confused as to what the car's acceleration would be. The DC motor on its own would instantaneously have an angular velocity of 1340...
Linear actuator spec.: 400mm stroke, 6000N, 2 limit switches, 5mm/sec, 12V DC supply, BIBUS IP65 casing.
One of the limit switches of my LA (Linear Actuator) seems to have burned out. This happened because I accidentally plugged the LA leads into the AC mains socket (my LA is rated to run at...
1. The two rotors (purple, green) are electricaly isolated but mechanically fit to rotate along same axis
2. The motor action on the left side rotor will move the armature set, this will produce currents in right side rotor that will pass via a variable load.
3. do you see the magnetic feilds...
Hi,
I have a problem that I've been trying to figure out for a while but cannot seem to get on my own. I'm trying to figure out how much power will be generated in a motor given a certain amount of torque. The problem is, to find the amount of power output , I also need to know the rotational...
Hello forum.
I'm looking for a DC motor for a little project. I don't have a lot of experience with different types of motors, though I'm fairly confident I don't want a servo motor or a stepper motor. I have a disk of non-uniform weight distribution. I want to mount the disk vertically (motor...
How can this DC motor work without a commutator. Should it not turn no more than once and then stop because on one side the rotor is attracted to the magnet?
An answer I can think of is that the rotor is repelled on one side and attracted on the other by the same force which neutralize each...
I need to buy a DC motor for an electric skateboard project. I need to calculate the speed at which it can travel with a person on top. I can calculate the speed at which the skateboard can go but is does not account for the weight of a person as that will surely decrease the speed. What formula...
Hello, I am working on a design, and I am having trouble selecting a motor. I will be able to supply 1.2 A and 12VDC, and I need the motor to be able to move a load of 0.5 lbs at 500 rpm. So far, I tried calculating torque (based on F=ma and T=Fr, r=1.06 in in this case). Then I used HP=...
Hello, I am building a large DC motor for a Go-kart.
I have a question: How would I know how much voltage and current (the maximum values I can use) I need to make the DC motor work and spin?
I'm guessing the armature size and the winded wire's length depends on how much voltage and current...
Hello,
I would like to start building a simple DC motor Go-kart, but I would like to build my own DC motor for it. A simple one that can make the car move.
I know how DC motors work and I understand the physics of it, but i'm not sure about some things:
- Are all DC motors (large or small) the...
I am creating a scale model wind turbine using a DC motor as a generator and would like to predict the motor response analytically. Generally speaking, the flow will spin the rotor (as in the turbine's), which will spin the motor, and then there will be what I'm calling the motor response, and...
I have a geared DC motor taken from a hand drill. When I manually turn the internal motor, the drill bit rotates. This can be done in both directions. However If I try and turn the drill bit it does not rotate.
What is the mechanism called that achieves this?
My friend says it is a sprag...
Hello,
I need to buy a DC motor for my project work. My project involves rotation of a cylindrical disk of 1 kg, inside water (approx. 2 cm below the water level) at different speed ranging between 100 rpm -200 rpm. For this purpose I need to buy a DC motor but I am not sure of what...
Hi guys,
I'm working on a school project and I don't know a lot about electricity, so here is my question. Lets say that I have two small 6V DC generators, and I need an output of 12V (I can not use a 12V DC generator because space is limited, the two 6V fit perfectly) is there a way to...
Homework Statement
A locked rotor test is performed on a permanent magnet DC machine with the following results:
Terminal Voltage 5 V DC
Input Current 10 A DC
Locked rotor torque. 20 Nm
a) Making suitable approximations deduce the effective rotor resistance in ohms?
b) Making suitable...
Good day. I was wondering if anyone could help me with the following problem. As you can see in the diagram below, I want to set up a circuit with 4 DC Motors in parallel, each with a push button switch. And a variable resistor to control the speed manually. I would like a LED strip to be...
Hi, i didnt know where to put this question cos its kind of multitopic, here is why...
I am working on a better way to take mechanical energy from muscles, i made a teste bench for pedalling in very different ways, including traditional(circular) pedalling, the thing is. I am measuring the power...
I'm looking at getting a motor to drive a micrometer. It's on an interferometer mirror for the curious. I'll need around 1RPM or so, but I want to be able to vary the speed, because I'm pretty unsure about how fast I'll need it to go for my experiment to work. I'm thinking a range of like 1/4 to...