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Questions tagged [thyristor]

A three-terminal semiconductor device consisting of four layers of alternating type (N or P). The main terminals are the anode and cathode, connected to opposite ends of the four layers. The third terminal is called the gate, and a current trigger at the gate causes the device to conduct if it is forward biased.

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Conduction of Thyristor and Diode

Consider the following circuit: Let \$ \phi \$ denote the angle for which the thyristor T1 is triggered, i want to know why when \$ \omega t = \theta \in (0, \phi) \$ T2 and D2 are conducting i see ...
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1 answer
181 views

Thyristor controlled 3-phase heater control, spiky current

Lets say you have 10 thyristor controlled heaters in a 3-phase system. The control of these thyristors is sync'd, so the current draw is spiky (all of the heaters draw current from the same phase when ...
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1 answer
197 views

SCR (thyristor) - Practical Dimmer Circuit

Could someone please explain the main function of the capacitor C3 connected between the gate of the thyristor (through the diac) and the cathode of the thyristor, in this Dimmer circuit schematic
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1 answer
222 views

Why is there a minimum current in a class-a chopper?

$$i_o(t) = {{{V - E} \over {R}} \cdot (1-e^{-{R \over L}\cdot t}) + I_{min} \cdot {e^{-{R \over L}\cdot t}}}$$ Where is the minimum current from, and why are we dividing by R? This is the link https:/...
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1 answer
62 views

Thyristor Choppers

I want to simulate this circuit to analyse its behavior: First I tried working the theoretic part of it: we suppose that the capacitor is charged initially thus \$ V_c = V_1 , i_l = -i_c = 0 \$ and ...
5 votes
2 answers
209 views

How to interpret critical rate of rise of on-state current in a thyristor datasheet?

I'm looking at a number of thyristors (for example, this N2593MK160). Each has a critical rate of rise of on-state current. This limitation surprised me; I don't understand why the derivative of ...
1 vote
0 answers
14 views

Quantifying the reduction in a thyristor's turn-off time in response to increasing reverse voltage: Seeking data or graphs

From a previous question of mine (here: What factors affect a thyristor's "circuit commutated turn-off time"?), which was asked about 5 years ago, a user presented this very helpful ...
2 votes
2 answers
100 views

Can a thyristor regain its forward/reverse blocking capability if the current through it is "instantly" brought to zero?

I am imagining a situation where we have several series-connected thyristors, say 10, each that can block a voltage of 100V. So, the ten series-connected thyristors together can block a total voltage ...
4 votes
2 answers
913 views

How does a TRIAC work?

I’m trying to understand the concept of a TRIAC. I’ve heard that a TRIAC is made with 2 SCRs (thyristors) connected in anti-parallel. But in the diagram I looked at, it looks like two SCRs were ...
3 votes
3 answers
407 views

Thyristor blowing up in a coilgun

I am making a six-stage coilgun. I know the optocouplers are switched in the diagram, but the thyristors keep blowing up. They are blowing up randomly. That's my fourth thyristor I have replaced. ...
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1 answer
88 views

SCR phase control

I'm making a battery charger with phase control. While making the circuit I had some doubts. The transformer has a center tap, in this way I can make a full wave rectifier without diodes. Then ...
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2 answers
385 views

Thyristor gate triggering issue

We are using an MOC3041 to trigger the gate of a thyristor (BT155Z-1200TQ). We use the circuit design from the datasheet of the MOC3041 (Figure 12: Inverse−Parallel SCR Driver Circuit). We detect zero ...
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2 answers
78 views

Turn on control of antiparallel SCRs to pass AC

If you are trying to pass an AC signal through antiparallel SCRs (there to isolate the signal when required) where the AC frequency is low enough to satisfy the turn-off time requirements during the ...
-1 votes
3 answers
430 views

What happens when we discharge a capacitor through a SCR which we leave open?

I am wondering what would happen when we discharge a capacitor, by using a SCR, through a coil and we leave a current applied to the gate of the SCR. The coil should generate a ‘reverse’ current right?...
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Are Bridge AC to DC Rectifiers using thyristors still considered Linear Rectifiers considering their switching mechanism of action?

While I tried not to make the title confusing, Whether if the question is about Non-Linear/Linear PSUs or just the Rectifier circuits, I believe This one covers both matters. Considering that the ...
1 vote
1 answer
508 views

Switching from full to half wave rectification

The Context: Multiple manufacturers of electro-magnetic brakes offer rectifier modules to switch their DC brakes with an AC feed. This can often be tied to the same phases turning the motor, so that ...
1 vote
0 answers
95 views

Is my basic coil gun schematic correctly wired?

Recently, I came up with the idea of integrating a coil gun into a marble machine to accelerate an iron marble. I've done a fair bit of research into other people's projects, and ended up mixing what ...
2 votes
2 answers
3k views

SCR inverter (thyristor H-Bridge) schematics/working principle?

Several online articles mention the so-called "Single phase SCR Inverter". Sample schematic is attached below. Source: Single Phase Full Bridge Inverter Explained | Electrical Concepts In ...
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1 answer
87 views

Unable to fire thyristor simscape electrical matlab simulink

Hello, I am unable to fire a thyristor on simscape. I have tried to connect the gate to a pulse generator with a simulink-ps conversion symbol but it doesn't work ( the lines will not connect). I ...
1 vote
1 answer
160 views

SCR gate drive options when optotriacs not suitable due to high voltage of 1600V

I am designing a 3-phase circuit to switch 1kV 50kW using thyristor pairs. The circuit is simple on/off switch, and needs to be simple as possible. I thought this precludes the use of pulse ...
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0 answers
144 views

Is it possible to make a halfbridge coilgun with high side IGBT and low side SCRs?

In a rather simple coilgun, the problem of freewheeling current from the coil is solved with a diode in parallel with the coil. The energy of the reverse current is wasted this way and even slows the ...
7 votes
2 answers
1k views

Series thyristor circuit

I want to build a pulsed energy source and consider up to 6 kV for the storage capacitor voltage. The application is similar to a defibrillator but not for medical purposes. So any insights into what ...
1 vote
0 answers
80 views

How can I control a DC circuit via a high voltage AC signal?

I have a low voltage circuit of 9V DC supply voltage and a bunch of LEDs, and another circuit with 50V AC voltage. I want the DC circuit to work only if there is current flowing in the AC circuit. I ...
2 votes
2 answers
664 views

Why are thyristor stacks hung from the ceiling?

The Wikipedia article on thyristors as well as the one on valve halls mentions that thyristor stacks in HVDC applications can be hung from the ceiling or supported by insulators mounted on the floor. ...
1 vote
1 answer
52 views

Thyristor T901N

The thyristor T901N in the Sinamics SL150 datasheet indicates constant operation limits based on temperature. In the datasheet, the continuous operation limits for this thyristor are as follows: ...
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1 answer
39 views

Can I use thyristor in place of pass transistor withvoltage regulator

I am making a circuit using an LR8 voltage regulator, and because the current may go over the recommended 10ma I will be putting a pass transistor to carry a little more current. The one I see most ...
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2 answers
58 views

MOC3020X phototriac: Does minimum latch current affect other specs of the IC?

I use MOC3020 IC to control a thyristor for AC mains voltage. My project works as expected and I would like to make an improvement on the current consumption, as I saw that there are other MOC302X ICs ...
2 votes
1 answer
110 views

Why is the SCR in this circuit switching off even though current is still above th holding current?

I am designing a circuit that controls DC power to a load through the use of SCR thyristors. I have been testing things out using the CLA20EF1200PZ part from Littelfuse. It has a 25 mA holding current ...
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111 views

Budget friendly battery charger controlled by phase angle ( SCR )

My circuit circuit is below so you can understand what I'm saying. I want to make a lead battery charger that can control the charging voltage and current (no discharge.) I have a circuit that ...
0 votes
1 answer
52 views

Is It Possible To Choose a Higher Holding Current When Designing SCR?

I'm looking at this data sheet: SCR data sheet on Digikey This device seems perfect for what I want to do, with 1 exception: The holding current is way too low. Various forums have suggested that (on ...
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4 answers
2k views

How does a capacitor and resistor affect an SCR's firing angle?

Greetings! High schooler here studying SCRs. I've been looking at sites and books on the concept of increasing an SCR's firing angle, and what I've noticed with these references is that they show you ...
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1 answer
275 views

Zero Crossing Detector for Microcontroller

Im trying to design a control circuit for charge a battery, for this i will be controlling the battery charge by a 40tps ( SCR ), phase control. So my little understanding for what i read is that i ...
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1 answer
10k views

Speed control of 3 phase induction motor using thyristor

I am working on project of controlling speed of 3 phase induction motor. To control the speed of motor I am using thyristor TYN16-600CT. As I am searching for ...
2 votes
1 answer
56 views

For sufficiently low duty cycle, can you get away with driving SCR above rated current as long as A^2 * s are maintained?

I'm wondering if the A^2-s rating of an SCR is what ultimately decides whether a given current for a given time is okay, even if the data sheet does not list such a number. For instance, right now I ...
0 votes
1 answer
2k views

SCR based rectifier vs IGBT based rectifier

I am wondering what is the difference in performance of rectifiers when used with SCR and IGBT. I searched on internet but all i can find is that IGBT is voltage triggered and SCR is current pulse ...
2 votes
1 answer
691 views

How to make a driver circuit / trigger circuit /gate circuit for SCR?

Ii would like to ask you for help to understand the SCR, thanks in advance! I also hope this question helps another to understand this device too I have read about SCR in Boylestad book but it's ...
0 votes
0 answers
98 views

Three-Phase Thyristor Bridge Converter Simulation on Matlab

I am looking for a 24 pulse rectifier to power an electrolyser using a universal thyristor bridge from matlab. I am using a phase shifting zig zag transformer for this. The transformers are shifted by ...
1 vote
3 answers
233 views

What is Vac(peak) in this question?

Bit confused at what Vm/Vac(peak) is. Either 230V or 325V. rest seems simple
1 vote
2 answers
130 views

Can an SCR conduct backwards in large amounts while the gate is asserted?

I am driving an inductive load and have a situation where an SCR will be forward biased but conduct in reverse. Can it do that if I strobe the gate the entire time I want it to conduct in reverse? ...
1 vote
0 answers
59 views

Connecting the GND of an isolated circuit to the positive side of a 450V transformer output

I moved to a new company that makes very big old-style controlled rectifiers. They asked me to make a new modified, and enhanced thyristor-controlled rectifier. The strangest problem I faced is that ...
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1 answer
120 views

Requesting clarity on the di/dt rating of thyristors

simulate this circuit – Schematic created using CircuitLab I have a general question about thyristors. I know that the di/dt limitation of thyristors is due to high currents flowing through ...
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49 views

Do commercial products exist for lab-scale thyristor triggering?

Hello fellow stack exchange members! We're excited about our novel high-voltage voltage-source-converter design that utilizes SCRs/thyristors and commutation circuits. We're now looking to build a ...
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3 answers
309 views

Calculating reactors for parallel connection of thyristors (SCRs)

I have been looking for more information on how to connect two thyristors in parallel in order to balance the load. From what I have found there are two options: either using balancing resistors, ...
2 votes
1 answer
343 views

Why does a MOSFET or IGBT's surge current rating stop increasing with decreasing pulse width beyond a point, unlike thyristors?

Thyristor The surge current rating of a thyristor increases as the width of the pulse decreases. For a single non-repetitive pulse, it's not uncommon for a thyristor to have a surge rating that is 10x ...
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Help with this 3-phase thyristor triggering board

I need a triggering board which is able to drive thyristors such as (s8006l), and I found this board on Aliexpress which might be the hidden gem I am looking for. enter link description here enter ...
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0 answers
69 views

What is the most efficient circuit to control a 3-phase controlled rectifier circuit with the ability to control the firing angle?

I am trying to design a board to control a 3-phase full wave rectifier with the ability to control the firing angle (alpha) through a potentiometer or a selector, and I was wondering what are the most ...
6 votes
1 answer
352 views

Floating high-side thyristor switch is destroyed by massive gate voltage undershoots

I'm building a capacitor discharger with a thyristor for high-voltage impulse generation into an inductive load. To make the circuit easier to use, I wired the thyristor as a high-side switch. Then I ...
5 votes
1 answer
807 views

What is the reason of difference in distributed gate thyristor design

As in the pictures, they use different designs (current rate, voltage rate etc. are same.) What is difference between these two designs?
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Difference between thyristor I(tsm) and I T(AV)

For example I have a capacitor send intermittent pulses to a coil send about 85A for few msec then off for 3-4 seconds (for 5mins) I was looking for a scr to switch it i found 40tps12 thyristor https:...
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2 answers
257 views

Connect two thyristor in parallel

I have 2 BTW69-1200 thyristor Vrrm = 1200 V Irms = 50 A I tsm (Non repetitive surge peak on-state current) = 610 (8.3 ms) - 580 (10 ms) Here is the datasheet https://pdf1.alldatasheet.com/datasheet-...

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