Power Conversion Apparatus Single Current Sensor Measurement
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Solution Overview
Problem
Uninterruptible power supplies face errors and phase delays when measuring inductor current and output current using two current sensors with different internal characteristics, leading to inaccurate synchronization.
Innovation Solution
A power conversion apparatus and uninterruptible power supply system that utilize a single current sensor to measure the resultant current, which is the sum of inductor and output currents, and employ a controller to separate and restore these currents without errors caused by sensor characteristics or phase delays, using a configuration of switches and filters to alternate current paths for accurate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two current sensors are used to measure inductor current and output current separately, then the currents can be measured independently, but measurement errors occur due to different internal characteristics of the sensors and phase delays arise during synchronization
Solution Approach 1:
The patent merges the measurement of inductor current and output current into a single measurement by using one current sensor to detect the sum current. The controller then separates these currents through calculation based on the relationship: sum current = inductor current + output current. This eliminates the need for two separate sensors and their associated synchronization issues.
Solution Approach 2:
The patent introduces sum current as an intermediary measurement that combines both inductor and output currents. By measuring this intermediate value with a single sensor and then mathematically separating the components, the system avoids the direct comparison and synchronization problems that would arise from using two separate sensors.
2Difficulty of detecting and measuring
If two current sensors are used to measure inductor current and output current, then both currents can be detected, but the device complexity increases and cost rises
Solution Approach 1:
The patent combines the functions of two current sensors into a single sensor by measuring the sum current. This reduces the number of sensors from two to one, simplifying the device structure, reducing component count, and lowering cost while maintaining the capability to detect both inductor and output currents through mathematical separation.
Solution Approach 2:
The single current sensor is made multi-functional by using it to measure the sum current, which contains information about both inductor current and output current. The controller processes this single measurement to derive both current values, making the sensor serve multiple measurement purposes simultaneously.
Data Source
AI summary
There is provided a power conversion apparatus including first to fifth nodes. The power conversion apparatus includes: an inverter including a first switch between the first and second nodes, a second switch between the first and third nodes, a third switch between the second and fourth nodes, and a fourth switch between the third and fourth nodes; a filter including an inductor connected between the second and fifth nodes and a capacitor connected between the fifth and third nodes; and a current sensor configured to sense resultant current, which is the sum of inductor current flowing in the inductor and output current, wherein the output current is output to a load connected between the third and fifth nodes.