# Questions tagged [synchronous-motor]

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### Why does inverter malfunctions when PCB is placed near metal enclosure?

I have designed a three phase inverter to drive a Synchronous motor. The motor operates fine when I place the PCB outside of the Aluminum enclosure of the motor. The voltage and frequency increases ...
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### What's the difference between a direct drive/torque motor and a stepper?

A torque motor is 'either a rolled-up linear motor or a classic servo drive with a large number of poles'. As I understand it they are ironless 3 phase supply motors, though perhaps neither of these ...
239 views

### Ratio of electrical input to mechanical input in a synchronous generator

In a synchronous generator we want to convert mechanical to electrical power but the thing that confuses me is that we also use electrical input as dc current which goes through rotor windings to make ...
24 views

### Is the per-unit internal voltage equal to the ratio of field current to no-load field current?

An example problem provides the following information to solve for the field current. The problem is below. A large 60 Hz synchronous generator can be considered to be round rotor, that is, xd = xq = ...
286 views

### How to measure the frequency of a low frequency signal?

I am looking to measure the rpm of a wind turbine, the wind turbine is 3-phase synchronous generator, the frequency range I am looking to detect is between 1Hz to 60Hz, I tried to use a frequency ...
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1 vote
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### Simple transient simulation model for synchronous generators

I am writing a simple transient circuit simulator as a personal hobby/experiment. My ultimate goal is to develop a simple 2D game for teaching/learning concepts of power systems in an intuitive way. I ...
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1 vote
378 views

### How to obtain the excitation voltage of a synchronous motor rated in horse power?

The synchronous motor rated at 120 hp, 460 V and 0.78 p.f-leading. The synchronous reactance is 2.51 Ω and armature resistance is 0.023 Ω. Since no frequency given in the question, how do we obtain ...
74 views

### Unexplained current perturbation with 3 PWM PMSM control

I encountered some problem of current measurement using the DRV8323RH to drive a PMSM motor in 3xPWM mode. I am running a test under the following conditions: 1 DRV8323RH gate driver configured in 3 ...
394 views

### Synchronous motor: intuitive explanation of f = 120/PN

In synchronous motors, let f be the frequence, P the number of poles and N the number of tours per second: $$f = \frac{120}{PN}$$ I don't understand this relation at all. In my opinion, the more ...
343 views

### Why am I getting Torque although stator and rotor fields are aligned?

I am working on a synchronous machine simulation project using FEMM. I am trying to find the rotor position that produces 0 torque. According to my understanding, this happens when both the rotor and ...
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1 vote
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### Effect of phase current on magnetic flux density in synchronous machines

I am working on a project on synchronous machines and I am testing different phase current values and observing the magnetic flux density in different parts of the machine, such as teeth, stator yoke, ...
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1 vote
282 views

### Does Back EMF change according to stator current in SM?

The concept of Back EMF always confuses me in Synchronous Machines. If I have a synchronous machine and I manually rotate at "x" rpm, do I get the same back EMF as when I excite the stator ...
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### modelling and simulation of a motor generator set for the replacement of diesel engines

Can a motor-generator set with specifications and outputs as shown in the picture below be used to power a 16 kW, 220V house?
163 views

### How are AC voltage regulation and overexcitation both accomplished in an AC synchronous motor?

Help me see what I'm misunderstanding here. I see a contradiction between the following two principles: An AC voltage regulator attached to an AC synchronous motor will regulate terminal voltage. If ...
281 views

### Which problem occurs with large synchronous motors in the event of high starting current?

So I was performing a test just recently with a synchronous motor at my school, and the teacher said that starting synchronous motors with a high starting current would cause problems to the machine. ...
289 views

### Combined Space and Time Phasor Diagram of a Synchronous machine

Consider a synchronous generator with its electrical and mechanical angles between them In the left diagram δ is in mechanical domain but delta is also the electrical angle between Ef and Er in the ...
1 vote
76 views

### Oversized electrical motor, synchronous, vs asynchronous

I know that a oversized motor would consume more energy than a well sized one, and in a low load scenario it will present a lower power factor than a well-sized one too. My question is, what is the ...
196 views

### Effects of decreasing the field voltage of a synchronous machine

I am running a simulation of a synchronous machine in matlab and I have some behaviour I cant quite grasp my head around. The machine is running as a motor with only about 20% of its maximum load, ...
4k views

### Number of poles used for calculating synchronous speed

I am a bit confused in the formula used to determine the synchronous speed $N_S$. Following is the formula used to determine the speed: $N_S = \frac{120f}{p}$ Now for a 6 pole motor there are some ...
2k views

When a single synchronous generator is operated alone adding a load on a synchronous generator the following happens: Adding inductive loads, |Eo| will increase, however, δ will not vary. Adding ...
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### overexcited generators and motors supply reactive power

I know that an overexcited synchronous motor has a leading power factor. But an overexcited synchronous generator has a lagging power factor. However, as shown in the attached page it says that ...
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### synchronous generator speed

Isn't a synchronous generator speed fixed at synchronous speed regardless of the load? In the question the synchronous generator has different speed why? Reference: Electrical Machines, Drives, and ...
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### What is the effect of stator magnetic flux on the rotor of Synchronous motor?

I get that the stator is fed 3 phase supply and the rotor is fed a dc supply. And it reaches a stage where the constant flux by dc current in rotor and the rotating magnetic flux by ac current in the ...
128 views

### Is the orthogonal spacing of dq axis of AC motor with respect to electrical or mechanical angle?

In FOC of AC machines, we try to align the stator flux to Q axis and maximize the value. The idea behind this logic is when rotor flux and stator flux are orthogonal, we generate max flux. But is the ...
94 views

### What is the standard procedure to design a Synchronous Machine?

I have Modelled an IPMSM based on the innovative idea i got. I have also decided on the rating of the machine, torque to be produced, Required Rated RPM, but after this i have so much doubt. whether ...
96 views

### Is the current in the correct direction in this image describing a one phase generator?

The dot on the left is current going towards us according to the image. But if the magnet is rotating counter clockwise while the conductor is stationary (which is same as magnet being stationary ...
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### Synchro with 1 phase grounded

I have been doing some research into synchros and I know the base equations from to determine the voltage difference between phases. Those equations can be used to determine the angular position from ...
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### Relation between torque angle, power angle and power factor

Considering a synchronous generator, is there a relation between power angle (angle between V terminal and V induced), torque angle (difference between rotor flux and stator flux) and power factor(...
58 views

### Steady State speed of rotor in following doubly excited system

I'm trying to analyse following system - A three phase armature winding on stator and on rotor field winding and both stator and rotor are cylindrical . And armature winding is connected to a three ...
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### Copper loss of a synchronous motor at a particular load

Imagine I'm driving a 50KW synchronous motor of full load current of 10A as a generator using a motor. Assume the driving motor losses to be negligible. Am I right about the following statements? When ...
1 vote
964 views

### Electrical frequency of motor with different stator and rotor poles

I know the formula to find electrical frequency when we have RPM and rotor poles of a synchronous machines which is f=RPM/60*pole pairs. I think the assumption here is that the number of rotor poles ...
140 views

### Explanation of v curve of sync machine

I am trying to understand the v curve of synchronous machine. Particularly, the point that changing field current can put the machine in leading or lagging mode. I am trying to get an explanation to ...
1 vote
1k views

### Tesla Model S inverter DC bus voltage

I was recently researching about this Telsa electric car inverters where i found one intresting thing. Usually in the voltage source inverter the DC bus voltage will be around 600 to 650 V considering ...
352 views

### How to find the 120 degree phase angle in a single layered lap winding of a synchronous machine?

Ok, so I have a 4 pole synchronous machine with 24 slots meaning each slot has a phase difference of 30 degree with respect to each other. 1)That means pole pitch is 180 degree for a full pitched ...
1 vote
317 views

### PMSM failure modes? Winding apparently not shorted

(This may look like a repair question, but I'm actually interested in how the simplest kind of motor failed) This is the stator of a permanent-magnet single-phase motor from a washing machine drain ...
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### Rotating rectifier waveform

I am testing a circuit which is used in a synchronous motor rotor excitation. I am testing the part when the rotor is stationary and the motor stator has a rotating magnetic field, in that case it ...
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664 views

### Motors in symmetrical fault analysis

In three phase symmetrical fault motors(Induction and Synchronous) become generators(I guess because of the inertia). When do I take in consideration of the motors? Do I even need take them in ...
2k 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?
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645 views

### What will happen if the prime mover driving synchronous machine is accidentally disconnected?

What happens to a synchronous machine connected to an infinite grid, acting as a generator, when its prime mover fails i.e. when mechanical input at the shaft reduces to 0? I'm assuming that the ...
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### 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 ...
1 vote
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### PMSM Rotor Design. Are these terms equivalent?

I'm working on a project with a PMSM. As I go through the literature I come across the following terms and wanted to make sure that I am getting right which ones are synonyms. Surface-mounted PM = ...
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### Electrical equivalence and Difference between Flux and Torque in AC motors

For AC motors, Synchronous and Asynchronous ones, are these two linked together or different quantities, namely magnetic flux and torque? Also if I want to measure these quantities electrically then ...
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### Controlling the reactive current of an PMSM in an open loop setting

for my master thesis I'm investigating the EMI of a 3-phase inverter, wich drives a PMSM. The inverter's structure is the common 3-Phase DC/AC Voltage Source Inverter and it uses EPC2020 GaN ...
479 views

You have a 500kVA load with a power factor of 0.6 lag. You add an additional synchronous motor with an input of 80kW and max power factor of 0.8 leading. Determine the reactive power and the overall ...
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### Medium Voltage Synchronous Motor Protection [duplicate]

How is the wound field of a medium voltage synchronous motor protected from voltage surges? We do know that the stator is protected from surges by either one of the following: 1. RC Snubber Circuit 2. ...
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1 vote
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### Which way should this capacitor go on this circuit?

Which way should this capacitor go on this AC Hysteresis Synchronous motor circuit? Which terminal is CCW and which is CW?
1 vote
240 views

### voltage transient protection for MV Motors

What types of transient voltage protection is applied on medium voltage motors and are these types of protection that are applied depended on the type of motor it is e.g Synchronous vs Induction motor?...
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### About how to extract back EMF from SMO(sliding mode observer), maybe I need a doctor for this question

The equations of PMSM on alpha-beta frame(2 ﬁxed coordinate systems) are like this, ...
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