Delay Correction in Power Factor Control for EV Charging
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Solution Overview
Problem
Existing power factor correction circuits in electric vehicle charging systems suffer from delays due to control unit filtering and sampling, leading to reduced response performance and increased total harmonic distortion, which affects charging efficiency and time.
Innovation Solution
A method and system that derive a delay correction input signal by comparing current and previous input signals, applying a conversion constant to correct signal differences, and using this signal to control the power factor correction circuit, thereby minimizing delays and improving power factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control unit filtering and sampling are applied to the input signal, then noise is reduced and signal quality is improved, but response delay increases and response performance deteriorates
Solution Approach 1:
The patent applies preliminary action by predicting future input signal values using a delay correction algorithm before the actual sampling occurs. The control unit calculates a delay correction input signal based on current and previous sampling values, effectively compensating for the anticipated delay caused by filtering and sampling operations. This allows the system to act in advance, maintaining response performance despite the inherent delays in signal processing.
2Device complexity
If conventional power factor correction control is used, then circuit simplicity is maintained, but reactive power is not sufficiently decreased and power factor is not sufficiently improved
Solution Approach 1:
The patent applies parameter changes by modifying the control parameter from simple voltage sampling to a delay correction input signal that incorporates historical sampling data. The control unit derives a corrected input signal using the formula Sc[k] = kp*(S[k] - S[k-n]), where the conversion constant kp and time constant n are optimized to achieve optimal power factor correction. This parameter transformation enables more effective reactive power compensation without adding complex hardware circuits.
3Speed
If sampling rate is increased to improve response performance, then response speed is improved, but processing time and computational load increase
Solution Approach 1:
The patent applies copying by creating a virtual representation of the input signal through mathematical processing of historical sampling data. Instead of increasing the actual sampling rate, the system generates a delay correction input signal that copies and extrapolates the signal behavior, allowing the control unit to respond faster without physically sampling at higher rates. This reduces processing time while maintaining improved response performance.
Data Source
AI summary
A method for controlling a power factor correction circuit includes: sensing, by a control unit, an input signal; deriving, by the control unit, a delay correction input signal using the input signal and a previous input signal that is sensed before the input signal; and controlling, by the control unit, the power factor correction circuit using the derived delay correction input signal.