# Designing Voltage Source Inverters for 50V Output Peak Voltage

• kiamzattu
In summary, anbullet is seeking information on how to design an inverter with specific parameters, including output peak voltage of 50V, input DC voltage of 55V, and a single phase full bridge configuration. They are using R and RL loads and a sinusoidal PWM to trigger MOSFETS. They are unsure of how to calculate load current and determine the ratings of their switching devices and overall inverter power rating. They are seeking a step-by-step procedure for inverter design and clarification on the use of PWM in obtaining output waveforms. They also clarify that their inverter only needs to supply real power.
kiamzattu
Hello every1

I hav a basic question bout Design of inverters(Voltage source inverters). Wel Actually what does designing mean?
I hav to design a inverter whose output Peak voltage is 50v. The input DC voltage wil b around 55V.I'm using single phase full bridge inverter And i'll b using R load in one case and RL in another case. Now wat r the other parameters tat r needed in designing an inverter. My output frequency is 50 Hz and I'm using sinosoidal PWM to trigger my switching devices(MOSFETS). Now how should i calculate wat is my load current?How do i determine the rating of my switching devices and power rating of my whole inverter? I'm entirely clueless. Is ther any step by step procedure for inverter design? any help is greatly appreciated.

Last edited:
First of all, please proofread your post. If every single sentence has multiple grammatical and structural mistakes, then it appears that you are not being serious. It shows your lack of care for the particular problem at hand.

Secondly, since this is appears to be a design project, most of your parameters will be logically determined by yourself. This allows you to view the design process, which is all about requirements and trade-off's. What are some trade-offs that can be associated with an inverter? What are some requirements for the particular design? I'm sorry to say, but for the most part a design project does not have detailed steps for you to take.

anbullet said:
Hello every1

I hav a basic question bout Design of inverters(Voltage source inverters). Wel Actually what does designing mean?
I hav to design a inverter whose output Peak voltage is 50v. The input DC voltage wil b around 55V.I'm using single phase full bridge inverter And i'll b using R load in one case and RL in another case. Now wat r the other parameters tat r needed in designing an inverter. My output frequency is 50 Hz and I'm using sinosoidal PWM to trigger my switching devices(MOSFETS). Now how should i calculate wat is my load current?How do i determine the rating of my switching devices and power rating of my whole inverter? I'm entirely clueless. Is ther any step by step procedure for inverter design? any help is greatly appreciated.

I agree with both of ravioli's points. anbullet -- check your PM box.

As to the questions, I'm not sure that you understand what a "power inverter" is. It generally is a device that takes in a DC voltage, and generates an AC output voltage, usually at AC Mains voltage levels (50Hz, 220Vrms, for example). The quality of the output "sine wave" waveform depends on how much you are willing to spend on the intermediate circuitry, and also on the character of the load impedance.

I don't know what you mean by "I'm using single phase full bridge inverter". By bridge, do you mean an H-bridge output stage? And what do you mean by sinusoidal PWM?

You could search at wikipedia.org for some background on inverter design, and use google to get the basics. If you have specific questions, point us to the page you are studying, and ask the specific question. And please take care to type carefully, and explain yourself clearly.

@ravioli
I'm really sorry for my grammar and spellings. English is not my mother tongue.
@ Berekman
Yes full bridge inverter is H-bridge inverter. Sinusoidal PWM means I'm comparing a sine wave and a triangular wave for generating PWM pulses.
I have my input voltage and output voltage values.
The quality of the output "sine wave" waveform depends on how much you are willing to spend on the intermediate circuitry, and also on the character of the load impedance.
I understand the above point. But before actually going into the output waveforms, I need to determine the ratings of my switches.what is the way to do that?

Hope I'm clear. Forgive me if not. Its the best of my grammar. took nearly 15 min to post it.

Thank you for the effort, anbullet, that makes it so much easier to understand your question.

I'm still a little hazy on the PWM part, though. Could you point me to a reference that describes how the PWM is used with the H-bridge to generate an output sinusoidal power waveform? I don't know enough about inverter design to know what is being done in the comparison you mention.

As for your switch ratings, they will need the V and I ratings to be large enough, and you will also need to check their Safe Operating Area (SOA) specifications, as the max I and max V ratings may not necessarily be used at the same time.

anbullet said:
Hope I'm clear. Forgive me if not. Its the best of my grammar. took nearly 15 min to post it.

I appreciate the effort. I'll try to post something tomorrow that will help you out. I don't necessarily have the greatest expertise with PWM, but I can look it up during the day tomorrow.

I do have one question, though. Will your inverter supply only real power, or will the inverter have to supply reactive power?

@ Berekman
PWM is just for switching the MOSFETS. When i compare a sine and a triangle,square pulses are generated. These pulses are used as switching signals and are given to the gates of MOSFETS.I've attached a pdf file giving a overview of how PWM is used in inverters to obtain output waveforms.

@ ravioli

My inverter needs to supply only real power.

#### Attachments

• PWM.pdf
33.7 KB · Views: 625
Anbullet, check out a few datasheets for IBGT's over at Mouser. They are fairly informative and will give you a few clues on what is out there, and what capabilities IGBT's have. Since PWM deals primarily with, well, pulses, you can assume that the resistive load will see the 50 volts at once at the during the pulses. From there, once you know the expected characteristics of the load, you can easily calculate what kind of pulsed current you should be expecting to go through the IGBT's.

Another note, I believe that the 55 Vdc source, and a 50 Vac peak output is fairly important. Since two transistors will usually be on, you will need to pay particular attention to the graphs in the datasheets. By symmetry of the circuit, you will only have a budget of about 2.5 Volts for Vce per transistor when the transistor is on.

Lastly, unless told otherwise, don't underestimate heat.

Thank you all for the help.
Will check out informations about IGBT and others.I still have some doubts, will post it after going through the datasheets.
Thanks again

Hi everyone
Before implementing the hardware part of my inverter i simulated my circuit using Simulink(MATLAB). I used a DC input source of value 55v, MOSFETS as my switching devices,PWM method for triggering them and output load of 50ohm. I've attached a screenshot of my output voltage.
Now i have some doubts in it. First of all my output peak value must be only 50volts. But I'm getting voltage spikes which cause my output to be around 54volts. Is there any way of eliminating these voltage spikes so that my peak output value is reduced (Preferbly 50volts)?

Secondly as you can see my output is not sinusoidal. I haven't added any filters in my circuit as of now. Can i add an LC filter ?Will a LC filter help in eliminating the switching frequencies so that my output is sinusoidal ( or atleast square) with a frequency of 50 hertz?
Is there any rule of thumb or steps to design LC filter so that it eliminates all the switching frequencies and allows only 50 hertz?

I know I'm asking too many questions, sorry for that.

#### Attachments

• Output.jpg
59.3 KB · Views: 501
hi,
well before i suggest u anything i wld like to knw the basic circuitry in your simulink.
may be i could help u with it because i too use MATLAB and as far as i knw u could be optimistic about ur output.
And yes with ur filter circuit try adding some reactive components in ur load.
Basically L & C, they work well for an approximate sinosuidal output.
Hope this may help u

## 1. What is a voltage source inverter?

A voltage source inverter is an electronic device that converts a direct current (DC) source into an alternating current (AC) source to power electrical devices.

## 2. Why is 50V output peak voltage important in designing voltage source inverters?

50V output peak voltage is an important consideration in voltage source inverter design because it determines the maximum voltage that can be delivered to the load. This voltage level is typically chosen based on the specific requirements of the electrical devices being powered.

## 3. What factors should be considered when designing voltage source inverters for 50V output peak voltage?

Some important factors to consider when designing voltage source inverters for 50V output peak voltage include the input voltage, switching frequency, power rating, and efficiency of the inverter. It is also important to consider the type of load that will be connected, such as resistive, capacitive, or inductive.

## 4. What are the different types of voltage source inverters?

There are three main types of voltage source inverters: single-phase, three-phase, and multilevel. Single-phase inverters are used for low power applications, while three-phase inverters are used for higher power applications. Multilevel inverters have multiple voltage levels and are used for high voltage and high power applications.

## 5. How can the efficiency of a voltage source inverter be improved?

The efficiency of a voltage source inverter can be improved by using higher quality components, minimizing losses in the switching circuit, and implementing advanced control techniques. Proper heat dissipation and cooling techniques can also help improve efficiency. Additionally, regular maintenance and monitoring of the inverter can help identify and address potential efficiency issues.

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