Harmonic Compensation Control for Power Converters Under Output Limits
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Solution Overview
Problem
Conventional power conversion devices struggle to effectively utilize their output voltage and current for harmonic compensation, leading to insufficient usage of available resources.
Innovation Solution
A power conversion device with a harmonic compensation unit that generates compensation current commands for each frequency component, using a limit coefficient calculation unit to optimize the compensation current based on the device's maximum voltage and current capabilities, ensuring effective harmonic compensation across multiple harmonic orders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If individual limit settings are applied for each harmonic order, then harmonic compensation can be performed with adjustable compensation ratio and gain, but the usage of voltage and current that the power converter can output is insufficient
Solution Approach 1:
The patent changes the control parameter from individual harmonic-order-based limits to a unified limit coefficient that applies across all harmonic orders. This limit coefficient is calculated based on the power converter's maximum output capacity and the sum of absolute values of compensation current desired values for all frequency components, enabling optimal utilization of output voltage and current while maintaining adaptability in harmonic compensation through the unified coefficient.
2Productivity
If maximum output capacity is prioritized, then usage of voltage and current is improved, but individual harmonic compensation control is lost
Solution Approach 1:
The patent creates a universal limit coefficient that serves multiple harmonic orders simultaneously. This single coefficient is applied to all frequency components in the compensation current command generation process, enabling the system to optimize overall output capacity utilization while still maintaining the ability to control compensation for each individual harmonic order through the unified coefficient mechanism.
Data Source
AI summary
A power conversion device includes: a power converter connected to an AC grid to which a load is connected; and a control circuit. The control circuit includes a harmonic compensation unit that includes a current command generation unit and a limit coefficient calculation unit and compensates for harmonic current contained in load current. The current command generation unit generates compensation current desired values for respective frequency components, and corrects the compensation current desired values using corresponding limit coefficients, to generate compensation current commands for respective frequency components. The limit coefficient calculation unit calculates each limit coefficient, on the basis of the compensation current desired value for each frequency component, and maximum voltage and maximum current that the power converter can output.