# Questions tagged [commutation]

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### Sensored Brushless DC Motor Back EMF Problem

I am working on the current control of a BLDC motor with a speed of 12000rpm. The current controller in the system is designed as PI. I give a reference value of 10A to control the motor and the ...
• 1
22 views

### how to implement external sinusoidal commutation using encoder feedback in BLAC motor?

I have a linear permanent magnet synchronous motor with sinusoidal back-EMF and a sinusoidal driver with current operation which takes two reference sine waves with a 120-degree phase difference, ...
50 views

### Universal AC Motor Brush Rotation Angle

Considering adding reversing capability to a Porter Cable 690LR (router) universal AC motor for use as a spindle motor. Yes, there are better alternatives but this is to finish someone else's wood-...
• 16k
199 views

### Three-phase full-wave bridge converter maximum firing delay

According to the textbook Power System Stability and Control by Prabha Kundur, the maximum firing delay of a thyristor is 180° with the following explanation: Why is he considering eb with ea? Doesn’...
• 376
115 views

### Problems of optimal commutation depending on number of pole

I am trying to design a three phase 4 pole motor, control with six-step. My problem appears when I draw the commutation to try to see how everything work. First, with a basic three phase 2 pole, there ...
• 21
1k views

### How is a line commutated inverter different from a grid-following inverter?

The U.S. Department of Energy provides this definition of a line commutated inverter: An inverter that is tied to a power grid or line. The commutation of power (conversion from direct current to ...
• 841
524 views

### trapezoidal bldc control oscilloscope artefacts

I am controlling a BLDC motor (24V, 125W) with this IFX007T board controlled by an STM32L412 MCU. The PWM frequency should be around 40kHz (I have 80MHz clock, counter period of 512-1 and prescaler of ...
334 views

### Commutation and triggering angle

I have circuit to analyze like this: L = 5 mH Vs = 230 V (RMS) Iload = 10 A constant Vda = 100 V I should calculate commutation (u) and the triggering angle but both are unknown. I tried to find ...
• 69
162 views

### BLDC does not start on its own using trapezoidal commutation

I am trying to control a brushless motor using trapezoidal commutation. I read the signals from the Hall sensors and switch the FETs of each motor phase accordingly. I run the commutation task at 1KHz....
• 1
155 views

### BLDC Y-shaped motor with Hall sensors generating different combination of back EMF on windings with different direction?

I have a BLDC Y-shaped motor. I connected the Hall sensors and winding to a logic analyzer to see the combination of back EMF on thr windings. My intention is to eventually create a commutation table ...
• 1
1 vote
803 views

### Confusion in magnetic neutral plane of DC machine

I was reading book Electric Machinery by Chapman and in topic 'Armature reaction ' It is written that "The magnetic neutral plane is defined as the plane within the machine where the velocity of ...
• 1,144
1 vote
223 views

### Why do I need two PNP BJTs as a switch rather than only one?

As far as I know, the circuit into the read circle works as a switch. I would like you to help me to understand how does the circuit works as a switch and why I need something so complicated instead ...
1 vote
200 views

### How to make an audio 5.1 switch?

I'd like to make a 5.1 audio switch to enable my 5.1 audio system (+mic+headphones) to be available for any of the 4 computers it can be connected to. So I guess I would have : INPUT : 4 (computers) ...
• 259
1 vote
83 views

### What is the effect of no-current periods in commutation on output power of a PM DC motor?

I have made a PM DC motor. This motor works on a unique magnetic circuit. This motor can work very well at different input levels. When it uses an input of 5.915 volts*3.5 Amperes=20.7025 Watts, its ...
61 views

### Sanity check for max motor torque

A KDE brushless DC motor has: Kt = 0.0189 N*m/A (Kv = 505 rpm/V) R = 7 mΩ voltage range of about 30-60 VDC Specsheet link Assume the motor is connected to 30 VDC input ideal, sensored, six-step ...
• 446
1 vote
78 views

### PMDC motor: how much is voltage reduced if the resistance produced by commutation system is eliminated?

I have made a PMDC motor. The resistance of the coils is 0.25 ohms. But the commutation system is very resistant. It adds more 0.85 ohms to the armature resistance. So, the total resistance becomes 1....
317 views

### BLDC commutation

I have some dilema with commutation on BLDC motor. I have driver for BLDC (MP6540) and I can commutate BLDC motor but motor it is heating up and speed is not appropriate (datasheet says that motor ...
695 views

### BLDC motor drive: Requires an external push to start rotating

I am trying to drive a 23-pole pair(i.e. 46 poles) BLDC motor using an LV8139 pre-drive, the output of which is fed to drive the 3 half bridge MOSFETs. I managed to connect the correct phase sequence(...
1 vote
3k views

### Why do the polarities of the capacitor change while discharging?

I was going through the working of class D commutation and the article said: As soon as the capacitor completely discharges, its polarities will be reversed but due to the presence of diode the ...
• 829
1k views

### What factors affect a thyristor's "circuit commutated turn-off time"?

In datasheets, they give this value at a certain operation point (voltage, current, and di/dt). My question is... What are the effects of changing these parameters. For example, if di/dt is ...
1 vote
38 views

### Is zero loss turn-off possible for thyristors?

Consider this very basic circuit: simulate this circuit – Schematic created using CircuitLab Don't mind the values - they don't matter, as this question is conceptual. Imagine that Vcomm is ...
108 views

### Looking for reed relays for high voltage commutation

I need to chose a reed relay for connecting a point to high voltage (probably between 7000V:15000V) or to GND signals. System will have 8 channels (pins). Some of 8 pins will be connected to high ...
• 787
1 vote
169 views

### Where exactly appears the channel capacitance and Ron when switch on DG442 switches

I have this switch in a circuit, actually there is 30 switches. https://www.vishay.com/docs/70053/dg441.pdf When system is not executing any operation, switches are off. Sx and Dx are not connected. ...
• 787
241 views

### SSRs influenced by physical proximity?

This is part of a two-head EVSE. The two solid-state relays are used to drive contactors that supply high current power to the vehicles. I used to use a MOC3040 based triac circuit for this job, but ...
• 1,543
131 views

### Commutation techniques in SCR

I read in a textbook that "Commutation Time is more in Current Commutation compared to Voltage Commutation".Kindly Elaborate.
• 47
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### Newbie question: Feasible way of amplifying 100+ channels of slow and low amplitude signal

I want to amplify signal coming in hundreds of channels (sensor array each producing a very low amplitude 30-200Hz signal). For every channel i care only about intensity of the signal (i don't need ...
5k views

### BLDC Motor rotor vibrates with audible high pitch beep, but does not spin. Controlled by custom motor controller

The circuit I have built (taken from the HIP4086A gate driver data sheet found at https://www.intersil.com/content/dam/intersil/documents/hip4/hip4086-a.pdf) is: The only difference between this ...
318 views

### LTspice diode commutation

I have modeled an ideal diode rectifier fed from a 230V/50Hz grid with a slim DC link capacitor and a constant power load (1kW) coupled with a small resistive load. For Cdc=14uF i get a phase input ...
86 views

### Commutation overlap symmetry

Let's say we have three phase diode (ignore SCR in the picture) rectifier: With no source inductance, diodes are conducting at following angles: Diode 1: 30º < X < 150º Diode 4: 210º < X &...
• 251
62 views

### How did rotary converter commutators conduct electricity?

I've been reading about rotary converters and examining photographs, but I've noticed that nearly all have a very strange (to me) commutator design. It looks like a piece of wire screen rather than ...
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### Quick specific questions about Electric Motors that I can't find on Internet

I want to talk about induction motors and Universal motors. 1) is the rotor of an Universal Motor a Wound rotor? 2) the induction motor with Wound rotor have commutators? 3) Universal Motor can ...
• 125
2k views

### Brushless DC motor problems at high velocities

For a project we use a brushless DC (BLDC) motor. Everything works fine until we tried to reach high velocities. I will first explain my setup, and than explain our problems using some graphs. ...
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