CVT Generator Control with Harmonic-Filtered Load Compensation
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Solution Overview
Problem
The existing power generation systems, such as those described in JP 2004-364459, face issues with excessive feedforward compensation due to higher harmonics in the electric power load, which can cause the frequency of the alternating current generated to fall outside a predetermined range, leading to unstable control of the speed change ratio in continuously variable transmissions.
Innovation Solution
A power generation system that includes a continuously variable transmission, a power generator, an electric power load calculation device, and a controller, where the calculation device detects current and voltage values of three-phase AC power, filters out higher harmonics, and the controller executes feedback and feedforward control to maintain a predetermined frequency, using pre-filters and post-filters to attenuate higher harmonics and prevent excessive compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If feedforward control is executed using calculated electric power load, then the frequency control response is improved, but excessive correction occurs due to higher harmonics causing frequency to fall outside predetermined range
Solution Approach 1:
The patent applies preliminary action by performing filtering of the electric power load calculation results before using them in feedforward control. The controller calculates electric power load from voltage and current, then filters this calculated value to remove higher harmonics, and only after this preliminary filtering action does it execute feedforward control. This prevents excessive correction while maintaining responsive frequency control.
2Measurement precision
If higher harmonics are included in electric power load calculation, then the control accuracy is improved, but excessive feedforward compensation occurs leading to unstable speed change ratio control
Solution Approach 1:
The patent applies the taking out principle by extracting and removing the harmful higher harmonic components from the electric power load calculation results. The controller calculates the full electric power load with high precision including all frequency components, then extracts and removes the higher harmonics through filtering, retaining only the fundamental frequency components for feedforward control. This maintains measurement precision while ensuring stability.
3Loss of time
If feedforward control is executed without filtering, then the control responsiveness is improved, but the frequency falls outside predetermined range due to excessive correction
Solution Approach 1:
The patent performs preliminary filtering of the electric power load calculation results before executing feedforward control. This preliminary action removes higher harmonics that would cause excessive correction, allowing the system to maintain fast response characteristics while ensuring frequency precision stays within predetermined ranges.
Data Source
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AI summary
A power generation system includes a continuously variable transmission, a power generator, a transmission driving device, an output-side speed detector, and electric power load device, and a controller. The electric power load calculation device detects current values and current values of respective phases of three-phase alternating current generated by the power generator, calculates electric power load of the power generator based on the detected voltage values and current values, and executes filtering work of attenuating a higher harmonic of a set frequency when calculating the electric power load of the power generator. The controller executes feedback control of calculating a gear change command and outputting the obtained gear change command to the transmission driving device such that an output-side rotational speed detected by the output-side speed detector becomes equal to an output-side target rotational speed corresponding to the set frequency. The controller also executes feedforward compensation of correcting the gear change command, calculated by the feedback control portion, based on the electric power load calculated by the electric power load calculation device.