Battery Current Estimation via Closed-Loop Inverter Switching
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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 current value estimation.
Innovation Solution
The system employs a three-phase inverter configuration with complementary arm circuits and current sensors to form closed-loop circuits, allowing current value estimation using only one current sensor's detection value, thereby avoiding the accumulation of sensor errors and improving accuracy.
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 decreases due to accumulation of sensor errors
Solution Approach 1:
The patent extracts and utilizes only the necessary detection value from one current sensor during specific inverter modes, eliminating the need to process multiple sensor readings. This selective extraction approach maintains comprehensive measurement capability while avoiding error accumulation from multiple sensors.
Solution Approach 2:
The patent segments the measurement process by dividing it into different inverter modes (first mode, second mode, third mode, fourth mode), where each mode utilizes detection values in a specific way. During first and second modes, only one current sensor's detection value is used, while third and fourth modes use the other sensor, thereby segmenting the error sources temporally.
2Measurement precision
If multiple current sensors are used to detect currents, then the system can measure currents in all phases, but the complexity of the system increases
Solution Approach 1:
The patent employs dynamic switching between different inverter modes, where the system adaptively changes which current sensor is actively utilized based on the current operating mode. This dynamic approach allows the system to maintain full three-phase current measurement capability while effectively using only one sensor at a time, reducing the practical complexity.
Solution Approach 2:
The patent makes the inverter modes multi-functional by designing them to serve dual purposes: normal operation modes (first and second modes) and diagnostic/estimation modes (third and fourth modes). This universality allows the same hardware to achieve multiple objectives without requiring separate dedicated circuits for each function.
Data Source
AI summary
An estimation system includes a battery, an inverter, a motor, a U-phase current sensor, and an ECU. The inverter includes U-phase upper and lower arm circuits, V-phase upper and lower arm circuits, and W-phase upper and lower arm circuits. A mode of the inverter includes a first mode in which the U-phase upper arm circuit, the V-phase lower arm circuit, and the W-phase lower arm circuit are on and a second mode in which the U-phase lower arm circuit, the V-phase upper arm circuit, and the W-phase upper arm circuit are on. The ECU performs estimation processing for estimating a current value of the battery. The estimation processing includes first processing for estimating the current value in accordance with a detection value from the U-phase current sensor when the mode of the inverter is set to the first mode or the second mode.