Self-adapting synchronous modulation method

A synchronous modulation and self-adaptive technology, applied in the control system, AC motor control, electrical components, etc., can solve the problems of truncation error, aggravate the instability and fluctuation of the actual frequency conversion output voltage frequency, etc., and achieve small truncation error and low voltage frequency. The effect of stabilizing and eliminating fluctuations in output current

Inactive Publication Date: 2012-08-22
DONGFANG HITACHI CHENGDU ELECTRICAL CONTROL EQUIP CO LTD
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AI Technical Summary

Problems solved by technology

However, due to the fixed control interruption frequency of the main inverter control system and the operating frequency of the inverter required by the user, it cannot be divisible by the modulation interruption frequency of the main inverter control system, resulting in a certain truncation error, which causes the output frequency of the actual voltage to fluctuate around the command frequency , and in the field application, the given operating frequency of the user is given by remote simulation. Due to the accuracy of the signal itself and the accuracy of the sampling system, the frequency received by the inverter main control system fluctuates to a certain extent, and this phenomenon will be exacerbated. Instability of actual variable frequency output voltage frequency

Method used

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Embodiment Construction

[0009] This specific embodiment takes the following technical solutions: its specific implementation method is: 1, initialize f according to actual working conditions First_loadfreq .

[0010] 2. According to the given output voltage frequency command f run calculate f First_loadfreq divide by twice f run remainder of .

[0011] 3. Calculate the new triangular carrier frequency f according to the remainder First_loadfreq .

[0012] The frequency of the triangular carrier wave is always an integer multiple of the modulated sine wave, and without greatly changing the switching frequency, the synchronous modulation of the entire frequency range during frequency conversion can be realized to avoid truncation errors.

[0013] This specific implementation mode adjusts the modulation frequency of the main control system in real time so that it can divide the instruction operating frequency by an integer, so that the generated truncation error is as small as possible, so that the...

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Abstract

The invention provides a self-adapting synchronous modulation method and relates to the technical field of speed control by frequency variation. The method provided by the invention is implemented through the following specific steps of: (1) initializing fFirst_loadfreq according to the actual working conditions; (2) calculating the remainder of fFirst_loadfreq divided by two times of frunn according to a given output voltage frequency instruction frunn; and (3) calculating a new triangular carrier frequency fNew_loadfreq according to the size of the remainder. According to the method, the modulating frequency of a main control system is adjusted in real time, so that an instruction operating frequency can be exactly divided by the modulating frequency, the generated truncation error is as small as possible, and thus the output voltage frequency is stable, and the condition of output current fluctuation caused by unstable output voltage frequency is eliminated.

Description

Technical field: [0001] The invention relates to the technical field of frequency conversion speed regulation, in particular to an adaptive synchronous modulation method. Background technique: [0002] For general-purpose VVVF frequency converters, the control of the motor stator voltage is carried out in an open-loop manner. According to a certain method, the controller outputs the expected value of the stator voltage and frequency of the motor, outputs the PWM command after being modulated by the PWM modulation link, and then connects the drive circuit to the control pole of the power switching device of the system inverter unit to control the output of the inverter unit Voltage. Obviously, if the PWM modulation link and the inverter unit can work ideally according to the expected way, the open-loop control method of the stator voltage can obtain a relatively ideal control effect. However, due to the fixed control interruption frequency of the main inverter control syste...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02P27/04
Inventor 张峻赖成毅张川唐斌付权伟
Owner DONGFANG HITACHI CHENGDU ELECTRICAL CONTROL EQUIP CO LTD
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