Harmonic content

Sorry but SVM stands for "Space Vector Modulation". A resume can be found in Wikipedia, but you may find thousands of papers on it in Google.

It was a fashion some years ago. In fact, you have to calculate the widh of every pulse on time, so if you have a DSP or a fast microcontroller with hardware multiplier/divider it is a reasonable option. Defenders of SVM said that it allowed full voltage at rated motor frequency, while PWM using a sine wave reference did not. As I am saying below this is not true.

PWM uses a reference wave stored in memory, and all the calculation to do is to get the value of the table and scale the value of the pulse width according to the modulation index . The table was per-calculated in your calculator and the PWM is free in most microcontrollers. So computer power on time is very low.

In PWM, if instead of a pure sine wave, you store a sine + 1/6 of third harmonic, you get full voltage at rated frequency. So the end results are the same in good SVM and good PWM. It depends on what are your means and your time. With the available cheap microcontrollers we have now, that have plenty of PWM outputs, I thing that PWM is the best and simplest option. You may use a very cheap microcontroller and program it in a very short time.

And an added benefit of the addition of third harmonic is the reducion of harmonics and motor losses.

Just some details if you want your PWM be as good or better than most SVM strategies: if you use PWM in a three phased inverter the number of elements of your wave table has to be a multiple of 6 (2 because of symmetry and 3 because of 120º phase), for example 252 elements. And pulses have to be centered, that is do not switch all the phases at the same time

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Dear Hossein,

the controller in motor-drives and generator-supplies use dq- or alpha-beta-coordinates. This controllers contains internal two separate controllers for every axis. The SVM is not more as "the PWM" for an input of two separate controllers. For example a controller there controls one machine field-oriented.

thanks

Christian E. Jacob · Max Planck Institute for Plasma Physics

Dear Hossein,

the controller in motor-drives and generator-supplies use dq- or alpha-beta-coordinates. This controllers contains internal two separate controllers for every axis. The SVM is not more as "the PWM" for an input of two separate controllers. For example a controller there controls one machine field-oriented.

https://www.researchgate.net/post/What_are_the_major_differences_between_PWM_and_SVM_systems#543d7a86d039b1be018b456a

Harmonic content

Hossein -

3 Phase Pulse Width Modulation compares 3, lower frequency, but

otherwise identical "modulation" frequency signals, each separated by 120

degrees of phase difference, to a higher frequency "carrier" signal in each

of the 3 phases concerned. On the other hand, Space Vector Modulation

(SVM) multiplexes various width, center aligned pulses, at a "carrier"

frequency making 3 longer wavelength "modulation" signals, each

separated by only 120 degrees of difference, regardless of "modulation" frequency. See patent# 9143080.

PWM is to control the gate signal like dc-dc converters i.e basic , SVM (Space vector modulation ) is to control the gate signal in inverter side but higher voltages we can use SVM