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Hysteresis random spread spectrum method in selective harmonic cancellation of inverter random pulse width modulation

A technology of pulse width modulation and inverter, applied in the direction of output power conversion device, conversion of AC power input to DC power output, electrical components, etc. Inverter instantaneous switching frequency and average switching frequency and other issues, to achieve the effect of simple algorithm, easy implementation, and strong control flexibility

Active Publication Date: 2022-07-29
LIAONING TECHNICAL UNIVERSITY
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The existing relevant literatures do not consider how to control the instantaneous switching frequency and the average switching frequency of the inverter when realizing selective harmonic elimination; nor do they give general formulas for the switching period, random number and the corresponding upper and lower limits of frequency. Lack of systematic analysis of the elimination mechanism for specific sub-frequency

Method used

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  • Hysteresis random spread spectrum method in selective harmonic cancellation of inverter random pulse width modulation
  • Hysteresis random spread spectrum method in selective harmonic cancellation of inverter random pulse width modulation
  • Hysteresis random spread spectrum method in selective harmonic cancellation of inverter random pulse width modulation

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Embodiment 1

[0039] A hysteresis random spread spectrum method in the selective harmonic elimination of inverter random pulse width modulation, such as figure 1 shown, including the following steps:

[0040] Step S1: Based on each cycle frequency f of the inverter m Summation to get the average value of the inverter switching frequency f An ;

[0041] Step S2: Set the upper and lower limits f of the frequency hysteresis 1 and f 2 ;

[0042] Step S3: Calculate the average value of the inverter switching frequency f An with the frequency hysteresis upper and lower limits f 1 and f 2 Make a comparison to get the hysteresis comparison result;

[0043] Step S4: according to the hysteresis comparison result, determine the average switching frequency error Δf;

[0044] Step S5: according to the value of the switching frequency error Δf, determine the random number k;

[0045] Step S6: Based on the random number k and the method of selective harmonic elimination, obtain the sampling period...

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Abstract

The present application proposes a hysteresis random spread spectrum method in inverter random pulse width modulation selective harmonic elimination, which belongs to the technical field of inverter pulse width modulation. Average value of inverter switching frequency; set the upper and lower limits of frequency hysteresis; compare the average value of inverter switching frequency with the upper and lower limits of frequency hysteresis to obtain the hysteresis comparison result; determine the average switching frequency according to the hysteresis comparison result error; determine a random number according to the value of the switching frequency error; obtain the sampling period at the next moment based on the random number and the method of selective harmonic elimination; assign a value to the comparison register according to the sampling period at the next moment , to generate the PWM drive signal of the single-phase inverter. The present application can distribute the harmonics concentrated at the switching frequency and its integer multiples in a relatively uniform distribution within the selected frequency range and realize random PWM control, which can selectively reduce the harmonics at a specific frequency.

Description

technical field [0001] The invention belongs to the technical field of inverter pulse width modulation, and in particular relates to a hysteresis random spread spectrum method in the selective harmonic elimination of inverter random pulse width modulation. Background technique [0002] In the traditional Sinusoidal Pulse Width Modulation (SPWM) strategy, the inverter switching frequency is usually fixed. More high-order harmonics will be generated at the switching frequency and its integer multiple frequencies; it is the main reason for electromagnetic vibration and noise of loads such as motors. Although increasing the inverter operating frequency can reduce electromagnetic vibration and noise, it is not suitable for applications where the switching frequency must be limited to a lower value, such as high-power traction drive systems. RPWM can concentrate the original harmonics on the switching frequency and its integer multiple frequencies, and evenly distribute them in a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/5395H02M1/12
CPCH02M7/5395H02M1/12
Inventor 赫飞沈家北李国华曹冬满杨涵杰
Owner LIAONING TECHNICAL UNIVERSITY
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