Power Converter Dead-Time Compensation via Phase Difference Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power converters face challenges in accurately performing dead-time compensation due to the difficulty in real-time detection of current phase, leading to distortion in output current, especially when reactive power is outputted, which further destabilizes the system.
Innovation Solution
A power converter configuration that includes a PWM controller, a calculating unit, a dead-time compensation unit, a current amplitude detector, and a changing unit, which calculates and applies dead-time compensation based on the amplitude of d-axis or q-axis current in a rotating coordinate system, allowing for accurate real-time compensation without significant computational load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dead time is set during which both switching elements are off to prevent simultaneous turn-on, then switching safety is improved, but output current distortion increases
Solution Approach 1:
The patent applies preliminary anti-action by calculating and adding dead-time compensation values to the PWM voltage command values before the dead time distortion occurs. The calculating unit computes compensation amounts based on detected current phases, and the dead-time compensation unit adds these compensation values in advance to counteract the upcoming distortion, thereby maintaining output current quality while preserving switching safety.
2Object-generated harmful factors
If voltage command value compensation is applied to reduce output voltage distortion, then voltage quality is improved, but accurate real-time dead-time compensation becomes difficult due to phase detection errors
Solution Approach 1:
The patent implements feedback by detecting the actual current phases, calculating compensation values based on these detected phases, applying the compensation, and then detecting the amplitude values of d-axis and q-axis currents to verify the compensation effect. The system uses this feedback information to iteratively adjust and optimize the dead-time compensation, ensuring accurate real-time compensation even with initial phase detection variations.
3Measurement precision
If FFT-based current detection is used to adjust current phase in real-time, then dead-time compensation accuracy is improved, but computational load and processing time increase significantly
Solution Approach 1:
The patent extracts only the essential information needed for dead-time compensation by directly detecting current phases and amplitudes without performing full FFT analysis. Instead of processing the entire frequency spectrum, the system extracts the fundamental current phase and amplitude information required for compensation calculations, significantly reducing computational complexity while maintaining the accuracy needed for effective dead-time compensation.
4Measurement precision
If deemed phase difference is adjusted to minimize d-axis or q-axis current amplitude, then dead-time compensation accuracy is improved, but system stability deteriorates when reactive power is outputted
Solution Approach 1:
The patent applies dynamics by making the deemed phase difference adjustable and adaptive rather than fixed. The changing unit dynamically modifies the deemed phase difference based on real-time detection of d-axis and q-axis current amplitudes to optimize dead-time compensation accuracy. This dynamic adjustment capability allows the system to adapt to varying operating conditions, including reactive power output scenarios, maintaining both compensation accuracy and system stability.
Data Source
AI summary
In a power converter that converts a direct-current voltage into three-phase alternating-current voltages and outputs the three-phase alternating-current voltages to a power system. The power converter includes a microprocessor that sets a dead time during which high-side switching elements and low-side switching elements are simultaneously off, and carries out switching. Moreover, the microprocessor performs dq transformation using complex numbers of phase currents, and detects an amplitude value of d-axis current or q-axis current. The microprocessor changes a phase difference to reduce the amplitude value of d-axis current or q-axis current. The microprocessor then performs dead-time compensation on the basis of the resulting phase difference.