# Firing angle in rectifiers and inverters.

by ramox3
Tags: angle, firing, inverters, rectifiers
 P: 12 Hello everyone I am a newbie to electrical engineering, I have this problem I've been strugling with, no textbook seems to cover this problem.. A three-phase, 440-V, generator delivers 5400W of active power through two recti-fies, A and B, into a three-phase, 230-V, line as shown in Figure 3. The dc current through the inductor is 20A. If power loss in both rectifiers are negligible, calculate: (a). Firing angle of the rectifier A; (b). Firing angle of the rectifier (inverter) B. This is my attempt ; V out = 5400/ 20 = 270 For inductive load VOUT = 1.35 × VLINE × cos α Where ‘α’ is the firing angle of the rectifier. Therefore, cos α = V / 1.35 x Vline α = 29 how does this seem? and how is the inverter's firing angle different?
 P: 12 1. The problem statement, all variables and given/known data Hello everyone I am a newbie to electrical engineering, I have this problem I've been strugling with, no textbook seems to cover this problem.. A three-phase, 440-V, generator delivers 5400W of active power through two recti-fies, A and B, into a three-phase, 230-V, line as shown in Figure 3. The dc current through the inductor is 20A. If power loss in both rectifiers are negligible, calculate: (a). Firing angle of the rectifier A; (b). Firing angle of the rectifier (inverter) B. 2. Relevant equations 3. The attempt at a solutionThis is my attempt ; V out = 5400/ 20 = 270 For inductive load VOUT = 1.35 × VLINE × cos α Where ‘α’ is the firing angle of the rectifier. Therefore, cos α = V / 1.35 x Vline α = 29 how does this seem? and how is the inverter's firing angle different?
 HW Helper Thanks P: 5,137 Where is Fig 3?
 P: 12 Firing angle in rectifiers and inverters. here's the figure :D http://imageshack.us/photo/my-images/69/figure3t.png
 P: 64 Not sure this is the right place to post this (perhaps this is why no one answers, but I don't know I'm new to PF). Here's some help: In fact, there are a lot of text books that cover this. For instance see "Power electronics", from Mohan. I can't see your Figure 3, but I assume you have a perfect voltage source connected to 2 full-bridge thyristor converters (1 rectifier, 1 inverter) and some load. There should also be an inductor on the DC bridge. To find the solution for rectifier A (source): $$P=V_{DC}I_{DC}$$ where the voltage on the DC bus is given by: $$V_{DC}=\frac{3\sqrt{2}}{\pi}V_{LL}\cos{\alpha}$$ where $V_{LL}$ is the line-line voltage of the AC side. The DC bus current is given in the problem, which is $I_{DC}$. Just isolate these for $\alpha$... For rectifier (inverter) B, same procedure, but by using a negative power and use the 230V line-line voltage. Isolate again for $\alpha$... This angle should be between 90 and 180 degrees since this converter is operating in inverter mode. M.