Formation of a stepped signal with minimum levels of the third harmonic

One of the important tasks of electronic instrumentation is the creation of powerful measuring generators of a sinusoidal signal, in particular, fictitious power generators for testing and verifying electricity meters. Such generators are usually digitally controlled. Get a high efficiency allows pulse-width modulation (PWM). However, when building a device based on PWM, there is a need to suppress higher-order harmonics. To simplify signal filtering, the switching frequency of the keys in the generator is increased, which reduces its efficiency. The paper presents a new method for obtaining a sinusoidal signal by adding three rectangular pulse signals having the frequency of the generated sinusoid, which makes it possible to suppress the 3rd harmonic and filter the harmonics starting from the 5th. This method allows, with high efficiency and a simple output filter, to form a sinusoid with a frequency of not only 50 Hz, but also significantly higher.