Bridge-Circuit Battery Testing With PWM and Analog Current Control
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Solution Overview
Problem
The reliability of charge and discharge characteristic evaluations for secondary batteries is compromised due to ripples or noise in the testing process, particularly for low output type batteries, where the noise-to-current ratio is high, making it difficult to obtain accurate results.
Innovation Solution
A charge and discharge testing device that employs a bridge circuit with switch elements and a control unit to alternate switching states for high output batteries, while using analog voltage control to minimize noise for low output batteries, allowing for reliable evaluation in both cases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If switching system is used for charge and discharge testing, then testing speed and productivity are improved, but measurement precision deteriorates due to ripples and noise
Solution Approach 1:
The patent dynamically switches between two control modes: PWM switching mode for high output batteries (prioritizing productivity) and analog voltage control mode for low output batteries (prioritizing measurement precision). The control unit automatically selects the appropriate mode based on battery characteristics, allowing the system to adapt its behavior to different testing scenarios.
Solution Approach 2:
The patent changes the control parameter from digital PWM switching signals to analog voltage control signals when testing low output batteries. This parameter change eliminates the high-frequency switching ripples and noise that plague PWM control, thereby improving measurement precision for sensitive low output battery testing.
2Loss of energy
If PWM switching control is applied, then power conversion efficiency is improved, but harmful factors increase due to switching ripples and noise
Solution Approach 1:
The patent acknowledges that PWM switching generates harmful ripples and noise, but converts this into a benefit by using the same PWM control for high output batteries where the signal-to-noise ratio is favorable. For low output batteries, it switches to analog control where the benefits of high efficiency are maintained through different means while avoiding the harmful switching artifacts.
Solution Approach 2:
The system dynamically adjusts its control strategy based on battery output characteristics. High output batteries benefit from PWM's high efficiency, while low output batteries benefit from analog control's low noise, allowing the system to optimize both efficiency and harm reduction for different operating conditions.
3Speed
If switching frequency is increased to improve response speed, then productivity is improved, but harmful factors worsen due to increased noise and ripples
Solution Approach 1:
The patent dynamically selects the control method based on battery type: PWM switching for high output batteries (where fast response is needed and noise is less problematic) and analog control for low output batteries (where slow response is acceptable but noise must be minimized). This dynamic selection allows the system to achieve fast response when necessary without always incurring the noise penalty.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device enables highly reliable evaluation of charge and discharge characteristics for both high and low output type secondary batteries by effectively managing noise and ripples, ensuring accurate testing results.
Implementation Method 1
a capacitor (C1) connected between the first and second output terminals
Implementation Method 2
a charge and discharge current path including a shunt resistor (SR) and a first inductor (L1)
Data Source
AI summary
A bridge circuit including first and second switch elements connected in tandem at a first connection point, and third and fourth switch elements connected in tandem at a second connection point, and a control unit which when a mode signal indicates a first mode, controls the first to fourth switch elements so that the first and fourth switch elements and the second and third switch elements are alternately turned on and off, and when the mode signal indicates a second mode, controls the third switch element to be off state and the fourth switch element to be on state, and applies analog output control to vertically change a current made to flow due to an analog voltage in which a voltage greater than or equal to a gate threshold voltage changes up and down, to the first switch element during charge control and the second switch element in charging.