# Questions tagged [electric-machine]

Electrical Machines are Electro-Mechanical energy converters. They maybe classified into motors (electrical -> mechanical) and generators (mechanical -> electrical).

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### Formula for calculating the MMF and its harmonics of n-Phase PMSM with integral slot winding (slot per pole per phase =1 & 2)?

Data\Prerequisites: Integral slot winding full pitch winding Slot per pole per phase = 1 and 2 (two different possibilities) Number of phases : n = 3,4,5,6,7 Assume number of turns = N and current to ...
36 views

### What is all properties of orthogonal axis (dq) axis?

We know about the transformation between abc three phase to dq0 axis which is orthogonal. BUT I am confused about What is the added value and all properties of orthogonality for dq0 axis that help in ...
591 views

### Why do some motors have high rpm while other have low even though having same power consumption

I have seen a 500w motor which run on 1200 rpm but a 300w motor with over 10000rpm . I know using a gearbox can give required rpm or torque and torque is inversely proportion to speed but how can I ...
42 views

### Voltage Difference Between Machine Laminations

Given a lamination stack that is exposed to a transient magnetic field, how can the potential difference between the individual laminations be determined? is there a rough rule of thumb that can be ...
175 views

### Does regenerative braking, using supercapacitors, really save fuel in the case of diesel city buses? [closed]

Does regenerative braking, using supercapacitors, really save fuel in the case of diesel city buses? A 10-ton diesel bus, fully loaded, that slows down, on average, from 30 km/h to 0 km/h each ...
31 views

### Which case count as leading PF in Salient plot generator?

In the figure above we can see the location of two armature currents. In case 1, $I_{a1}$ is leading $Vt$ (terminal voltage) but lagging $E_f$ (excitation voltage). In case 2, it is obvious that ...
35 views

### When do the positive sequence negative sequence, and zero sequence apprea?

I have analyzed three phases current in different cases, but I am still confused about some cases. Positive and Negative sequences are appeared but not the zero. Zero sequences is appeared, while ...
105 views

### Can someone tell me what this machine is? [closed]

It has two probes on two cables. I think it might be an xray machine but I can not be sure since there is no readable info on it. Can someone please identify it?
460 views

### Tesla model 3 motor

The Tesla's model 3 uses IPM-SRM motor in the rear drive. This motor is fed by AC supply OR DC supply? Is the motor's stator is of salient pole construction OR the same stator as of the induction ...
143 views

### Why earth pin in plug is larger than the other pin?

Why main line pin is not bigger ,the work of main line pin is more important than earth line? And the flow of electricity is also pass through main line and neutral pin then why earth pin is larger ...
349 views

### Why are the poles of the stator and rotor taken differently in the picture below?

The rotor and stator in the picture below have the same orientation of flux lines yet the are taken as opposite that is flux lines leaving the stator is taken as a South Pole while flux lines leaving ...
63 views

### Are the emissions to power electric cars really better for the environment than the emissions from petrol cars? [closed]

In my country most of the electricity is generated by coal which is then in turn used to power electric cars, which I don’t think is to good for the atmosphere, is there any prof that this is better ...
378 views

### What happens to the Real and Reactive power when I increase the excitation current in a 3-Phase Synchronous Generator?

Basically my doubt is, for the same load, why does the Real power remain constant when I increase the excitation current?
123 views

### Are permanent-magnet motors equally (in)efficient as motors vs. as generators?

Given a permanent-magnet motor with an efficiency of 80% that converts 100W electrical input power into 80W mechanical output power, would the motor have the same efficiency if used as a generator? ...
73 views

### AVR Excitation System and Generator in SimuLink

I am designing in simulink cooperation of synchronous machines with the grid. The main blocks are Excitation System which is AVR [link1] and Synchronous Machine [link2]. On the site we can find "...
81 views

### In 3 phase induction motor how many phase will be generated in wound type and squirrel cage rotor?

In 3 phase induction motor how many phase will be generated in wound type and squirrel cage rotor? If we consider a generator when the rotor rotates there will be voltage induced in every pole of ...
78 views

### Understanding of torque constant and efficiency of a permanent magnet motor from datasheet

I am trying to understand the efficiency of the following permanent magnet synchronous motor Motor Datasheet (note we are using the medium voltage model), and its relationship with the input voltages ...
697 views

### How brush shifting affects current distribution in dc machines?

I understand that how armature reaction causes neutral plane to shift by some angle . If brushes are placed along Geometrical Neutral Axis, then there'd be sparking during commutation as voltage ...
25 views

### Mean Free Path of Magnetic Core

I don't understand how they got the mean free paths (ls) of each leg. I know that I should be calculating the longest + the shortest paths and divide them by two, but I don't know HOW I should be ...
3k views

### If a high rpm motor is run at lower rpm, will it produce more torque?

I did the following calculations: Max current = 1.2A, Max voltage = 12V Then power = 14.4 watts = 0.019hp Rpm = HP * 5252 ÷ torque I need a torque to 2kgf-cm = 0.144 lb-ft Gives rpm= 698. Thus this ...
209 views

### why induction motor torque oscillating?

why when start induction motor the torque oscillate before become constant, like the following matlab torque simulation graph .
30 views

### Can torque angle of motor be positive?

For any motor text say that, the rotor field follows the stator field with a certain torque angle. And in case of generator, the stator field follows the rotor field with a negative load angle. The ...
152 views

### Hidrogen generator - electric problem

I made an Hidrogen generator (HHO) like YouTube : https://m.youtube.com/watch?v=zq8YMON9hjA&list=PLPCtNZjqSVUhWVzuxEkzlyrz1CatH8OiF&index=29&t=504s but , it does not working at all. ...
128 views

### Automotive alternator

I have been working on a project where so called Lundell alternator plays a crucial role. I haven't got any experience with this device sofar so I have decided to study some literature regarding this ...
60 views

### Electric brushed motor for electric car project

I am using a 24v 11amp 5700 rpm motor for a single seater car project. The problem is that when i am connecting the motor directly to the batteries without any throttle or control the vehicle shaft ...
57 views

### Sources and References for Motor Selection [closed]

So, I was wondering if there is a book/textbook which discusses the issue of selecting the proper motor for a job. The type of it (induction, synchronous, DC, etc.) and mainly the nominal power of it. ...