Inverter Phase Error Compensation via Pre-measured Voltage Feedback
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Solution Overview
Problem
Existing inverter systems face performance impediments due to time delays in voltage measurement caused by digital signal processing and analogue filter time constants, leading to errors in inverter output voltage detection.
Innovation Solution
A phase compensation apparatus that converts 3-phase voltage information into d-axis and q-axis voltages, determines voltage sizes, normalizes command voltages, and calculates phase errors to output a compensation voltage matching the inverter output voltage's size and command voltage's phase, effectively compensating for time delays in voltage detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If digital signal processing is used for voltage measurement, then measurement flexibility and control capability are improved, but time delay increases due to sampling and processing steps
Solution Approach 1:
The patent applies preliminary action by measuring the inverter output voltage in advance before the PWM switching operation, and using this pre-measured voltage information for feedback control. The measurement is performed at a timing that allows the control system to compensate for the inherent digital processing delay, effectively predicting the required voltage state before the actual switching occurs.
Solution Approach 2:
The patent implements preliminary anti-action by calculating and applying a phase-compensated voltage command that anticipates and counteracts the time delay effect. The control system pre-calculates the necessary voltage adjustment to compensate for the expected measurement and processing delay, thereby eliminating the adverse phase shift before it affects system performance.
2Stability of the object's composition
If analogue filter is used for voltage detection, then measurement smoothness is improved, but system response speed deteriorates due to filter time constant
Solution Approach 1:
The patent measures the inverter output voltage in advance at a timing that allows subsequent filtering and processing without compromising the overall response speed. By performing the measurement before the PWM switching and using this pre-acquired data for control calculations, the system achieves smooth filtered measurements while maintaining fast response capability.
Solution Approach 2:
The patent dynamically adjusts the measurement timing and filtering approach based on the operating conditions. The control system optimizes the balance between filtering smoothness and response speed by adaptively selecting measurement instances and processing methods, allowing the system to maintain measurement quality while responding quickly to changing load conditions.
3Measurement precision
If phase compensation is performed using coordinate conversion and normalization, then voltage detection accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent introduces intermediate coordinate systems (stationary and rotary reference frames) as mediators to simplify the phase compensation process. By transforming the voltage measurements into different coordinate systems and performing normalization operations in these intermediate frames, the complex phase compensation calculation is broken down into manageable steps that can be efficiently implemented in digital signal processing.
Data Source
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AI summary
A phase compensation apparatus in an inverter output voltage in a system is provided, whereby performance of an inverter can be enhanced by compensating a time delay of measured voltage of inverter output voltage detection unit.