Power Converter Control for Harmonic Interference Suppression
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Solution Overview
Problem
Interference and fluctuations in output power occur between control systems of multiple power conversion apparatuses due to closeness in frequencies of bus harmonic components and switch harmonic components, leading to unstable output voltage.
Innovation Solution
A control apparatus that includes an operating unit and a spectrum changing unit to separate or reduce the frequencies of bus harmonic components and switch harmonic components by adjusting the carrier frequencies of power conversion apparatuses, ensuring a predetermined difference between them to prevent interference and fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple power conversion apparatuses operate with the same carrier frequency, then the control system is simple and synchronized, but interference occurs between bus harmonic components and switch harmonic components causing output power fluctuations
Solution Approach 1:
The patent applies parameter changes by adjusting the carrier frequency of at least one power conversion apparatus to create a predetermined frequency difference between bus harmonic components and switch harmonic components. This frequency parameter modification prevents spectral overlap and interference, thereby stabilizing output power without requiring complex control mechanisms.
2Reliability
If the carrier frequency is adjusted to separate harmonic spectra, then interference is reduced and output stability improves, but the control complexity and frequency coordination difficulty increase
Solution Approach 1:
The control apparatus modifies the carrier frequency parameter of power conversion apparatuses to achieve spectral separation. By establishing a predetermined frequency difference, the patent ensures that bus harmonic components and switch harmonic components do not overlap, thereby improving output voltage stability while maintaining manageable operational complexity through systematic frequency management.
3Reliability
If multiple inverters operate independently without frequency coordination, then each inverter can be controlled simply, but interference occurs causing torque fluctuations in connected motor generators
Solution Approach 1:
The patent implements parameter changes by establishing a predetermined frequency difference between the carrier frequencies of multiple power conversion apparatuses. This approach separates the spectral components to prevent interference that would cause torque fluctuations, thereby improving torque stability while using a relatively simple frequency coordination mechanism.
Data Source
AI summary
In a control apparatus for a power conversion apparatus, a spectrum changing unit changes a spectrum of at least one of bus harmonic components and switch harmonic components so as to meet at least one of a separation condition and a reduction condition. The bus harmonic components are harmonic components superimposed on a voltage of the bus in accompaniment with on-off operations of switches configuring at least one power conversion apparatuses. The switch harmonic components are harmonic components included in a switching pattern of switches configuring the remaining at least one power conversion apparatus. The separation condition is that the frequencies of both harmonic components are separated by a predetermined value or more. The reduction condition is that an amplitude of at least one harmonic component is reduced when the difference between the frequencies of both harmonic components is less than the predetermined value.