A Combined Local Multiplication Sampling Algorithm for Spwm Wave Generation

Abstract

The invention discloses a combined local frequency multiplication sampling algorithm for generating SPWM waves. A symmetrical region is obtained with the zero point of a sine curve as the midpoint, and virtual sampling points are constructed in the region according to a linear combination mode in mathematics so that the effect of frequency multiplication can be achieved; under the situation that the number of the actual sampling points is definite, harmonic energy will gradually move in the direction of a high frequency along with the increase of the width of the region of frequency multiplication or the increase of number of frequency multiplication, and thus the energy of low-order harmonic components is reduced. According to the combined local frequency multiplication sampling algorithm for generating the SPWM waves, harmonic energy is transferred to a high-order harmonic region, the low-order harmonic components can be filtered out easily, and control signals more close to sine waves can be obtained; the algorithm is simple and easy to realize in a programming mode, and is mainly applied to rectifiers and inverters.

Description

technical field [0001] The invention belongs to the field of power electronics, and in particular relates to a combined local frequency multiplication sampling algorithm for generating SPWM waves, which is mainly used in servo motor control, inverter power supply, frequency converter, rectifier and the like. Background technique [0002] With the rapid development of microprocessor technology, computer technology, power electronics technology, automatic control theory and other related disciplines, inverters using pulse width modulation (PulseWidth Modulation, PWM) technology have become the most basic in contemporary power electronics technology. One of the devices. Since the emergence of PWM technology, PWM technology has been widely used in the fields of servo motor control, UPS, rectifiers and frequency converters due to its flexible frequency modulation and voltage regulation methods and excellent performance. So far, almost all the variable frequency speed regulators ...

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Problems solved by technology

[0003] (1) For rotary motors, harmonics will cause torque ripple, increase power consumption (copper loss and iron loss) to cause heat generation, and may even cause vibration or resonance

In addition, harmonics will cause electromagnetic noise in motors or inverters, polluting the environment

[0004] (2) For capacitive loads, some harmonics will also make it resonate, and the harmonic current will increase, resulting in damage to the capacitor due to overload or overvoltage

[0005] (3) For the transformer, increasing its load loss, especially when resonance occurs, the harmonics will also be amplified by the transformer, which will greatly increase its loss, and even cause serious power accidents

[0006] (4) For the power system, it may cause malfunction of relay protection and automatic control devices, and make the measurement of electrical measuring instruments inaccurate, affecting power monitoring

[0007] (5) Electromagnetic interference (EMI) generated by harmonics will interfere with adjacent communication systems, which may cause noise and reduce communication quality; severe cases may cause information loss and make the communication system unable to work normally

Although this method can eliminate the specified low-order harmonics well, the amplitude of the remaining un-eliminated lower-order harmonics may be quite large, and it also has the disadvantage of complex calculations. This method is also only suitable for synchronous modulation in the way

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