Battery Current Estimation in Three-Phase Inverter Closed-Loop Modes
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Solution Overview
Problem
Existing estimation systems for power storage devices suffer from accuracy issues due to errors in detection values from multiple sensors, leading to inaccurate estimation of current values.
Innovation Solution
The system employs a three-phase inverter with complementary leg circuits and current sensors to form closed-loop circuits, allowing current estimation based on a single detection value, and includes redundant sensors for failure diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If detection values from multiple sensors are used to calculate the estimated value, then the system can obtain comprehensive measurement data, but the accuracy of the estimated value deteriorates due to accumulation of errors from each sensor
Solution Approach 1:
The patent extracts and utilizes only the necessary detection value from a single current sensor during specific inverter modes (first and second modes) to calculate the battery current, eliminating the need to use multiple sensor detection values and thus avoiding error accumulation while still obtaining sufficient measurement data for accurate estimation
2Loss of information
If multiple sensors are used for current detection, then more measurement data is available, but the system complexity and cost increase
Solution Approach 1:
The patent dynamically selects which current sensor detection value to use based on the inverter's operating mode. During first and second modes, the system uses detection values from current sensors in a dynamic switching manner, allowing accurate battery current estimation with minimal sensor usage, thereby reducing device complexity while maintaining measurement data availability
3Device complexity
If a single current sensor is used for estimation, then the system complexity is reduced, but the reliability decreases due to lack of redundancy for failure diagnosis
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors the detection values from current sensors and compares them against expected values during different inverter modes. This feedback system enables failure diagnosis of current sensors by detecting abnormal detection values, thereby maintaining reliability with reduced sensor quantity through intelligent monitoring and comparison
Data Source
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AI summary
An estimation system includes a battery (5), an inverter (20), a motor (25), a current sensor (30u), and an ECU (100). The inverter (20) includes an upper arm circuit (22u) and a lower arm circuit (23u), an upper arm circuit (22v) and a lower arm circuit (23v), and an upper arm circuit (22w) and a lower arm circuit (23w). A mode of the inverter (20) includes a first mode in which the upper arm circuit (22u), the lower arm circuit (23v), and the lower arm circuit (23w) are on and a second mode in which the lower arm circuit (23u), the upper arm circuit (22v), and the upper arm circuit (22w) are on. The ECU (100) performs estimation processing for estimating a current value of the battery (5). The estimation processing includes first processing for estimating the current value in accordance with a detection value from the current sensor (30u) when the mode of the inverter (20) is set to the first mode or the second mode.