Pulse Signal Impedance Analysis for Real-Time Battery State Estimation
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Solution Overview
Problem
Existing impedance analysis methods for electric vehicle batteries lack accuracy and real-time capability, as they rely on open-loop voltage measurements that are not representative of the battery's on-line state, and require complex AC frequency conversion signals, leading to poor SOC and SOH estimation.
Innovation Solution
An impedance analysis device and method that uses a signal generator to supply a pulse signal to an object under test, acquiring and analyzing the response signal to obtain impedance variation characteristics, allowing for accurate real-time estimation of SOC and SOH without the need for complex AC signals or look-up tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If open-loop voltage measurement is used to calculate electrochemical capacity, then the measurement can be performed, but the accuracy of SOC and SOH estimation is poor because the measurement is not taken under on-line state
Solution Approach 1:
The patent applies periodic action by using pulsed current signals instead of continuous DC current. The pulsed signal allows the battery to be probed at specific intervals during operation, capturing impedance characteristics under actual on-line conditions while minimizing disruption to normal battery function. This periodic probing enables accurate SOC and SOH estimation without requiring the battery to be in a rest state.
Solution Approach 2:
The patent implements self-service by having the battery manage its own monitoring needs through the pulsed current technique. The same battery system that is being monitored also provides the probing signal, eliminating the need for separate measurement systems that would require the battery to be taken offline. The battery's own operational state serves as the measurement condition.
2Productivity
If AC frequency conversion signal is supplied to obtain real-time internal parameters, then real-time SOC and SOH can be obtained, but the circuit design becomes more complicated leading to higher production costs
Solution Approach 1:
The patent extracts only the essential measurement function from complex AC impedance analysis systems. By using simple pulsed current signals instead of full AC frequency conversion, it removes unnecessary circuit complexity while retaining the core capability to measure real-time battery parameters. This extraction approach keeps the system simple yet effective for SOC and SOH estimation.
Solution Approach 2:
The patent employs inexpensive pulsed current generation instead of costly AC frequency conversion equipment. The simple pulse circuit requires minimal components and can be implemented with basic electronics, dramatically reducing production costs while still providing real-time measurement capability. The approach trades measurement sophistication for cost-effectiveness.
3Ease of manufacture
If DC impedance and open-loop voltage are used to calculate electrochemical capacity, then the measurement process is simple, but the result is not updated in real time
Solution Approach 1:
The patent achieves continuous measurement through pulsed current probing that can be performed repeatedly during battery operation. Unlike single-point DC impedance measurements, the pulsed approach allows continuous updating of SOC and SOH estimates as the battery operates, providing real-time information while maintaining system simplicity. The useful action of measurement continues throughout the battery's operational life.
Data Source
AI summary
An impedance analysis device adapted to an object under test (OUT) includes a signal generator, a signal analysis unit and a processing unit. The signal generator outputs a pulse signal to the OUT. The signal analysis unit acquires a response signal which the OUT responds to the pulse signal, and analyzes the response signal to obtain an analysis parameter. The processing unit coupled to the signal analysis unit receives the analysis parameter, so as to obtain an impedance variation characteristic of the OUT.