Power Converter Dead Time Control With Phase-Shifted Current Correction
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Solution Overview
Problem
In electric-power conversion apparatuses, the dead time setting for switching devices is prone to errors due to phase shifts in current detection, leading to increased conduction losses and the risk of arm short circuits, particularly when dealing with AC currents.
Innovation Solution
An electric-power conversion apparatus that includes a dead time setting unit capable of correcting current errors caused by phase shifts between detected and actual current values, allowing for precise adjustment of dead time based on corrected current values to minimize losses and prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the dead time is shortened to reduce conduction losses, then energy efficiency is improved, but the risk of arm short circuits increases due to current detection phase shifts
Solution Approach 1:
The system performs preliminary correction of current detection values by calculating phase shift amounts and applying compensation before using these values for dead time setting. This advance correction ensures accurate current information is available when determining the optimal dead time, preventing short circuits while minimizing conduction losses.
Solution Approach 2:
The system implements feedback by continuously monitoring the relationship between detected current values and actual current states, calculating phase shift amounts, and adjusting dead time settings based on corrected current information. This closed-loop approach maintains reliability while optimizing energy efficiency.
2Volume of stationary object
If the switching frequency is raised to downsize the capacitor, then the capacitor volume is reduced, but the controllability deteriorates due to increased proportion of dead time
Solution Approach 1:
The system dynamically adjusts the dead time setting based on corrected current values and switching frequency. By making the dead time adaptive rather than fixed, the system maintains effective controllability even at higher switching frequencies where the capacitor can be downsized.
3Loss of energy
If the dead time is changed based on detected current values, then the conduction loss is reduced, but setting errors occur due to phase delay between detected and actual current values
Solution Approach 1:
The system calculates phase shift amounts in advance and applies correction to current detection values before using them for dead time determination. This preliminary correction eliminates setting errors while enabling optimal dead time adjustment for reduced conduction losses.
Solution Approach 2:
The system replaces direct use of raw current detection values with computationally corrected values that account for phase shifts. This substitution of corrected data for raw measurements eliminates precision errors while maintaining the ability to optimize conduction loss.
Data Source
AI summary
There is provided an electric-power conversion apparatus in which a dead time can be set, while in an electric-power converter in which an AC current flows in a series circuit of switching devices, there is considered the effect of an error between a current value obtained for setting a dead time and an actual current value at a time of setting the dead time. An electric-power conversion apparatus, for a series circuit of each set, obtains a value of a current flowing in the series circuit is obtained; for an obtained current value, corrects a current error caused by a phase shift between a value of an actual current at a time when the dead time is set and the obtained current value; and set the dead time based on the corrected current value.