Battery Equalizing Circuit with Feedback Current Control
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Solution Overview
Problem
Existing battery equalizing circuits face challenges in maintaining a constant equalizing current due to variations in temperature, voltage, and device differences, leading to unsatisfactory balancing and potential overcurrent risks.
Innovation Solution
A battery equalizing circuit with a feedback control circuit, comprising a current detecting resistor, equalizing inductor, and control switches, which adjusts the duty ratio of PWM or PFM signals to maintain a constant equalizing current by switching between circuit loops based on voltage drop across the resistor, using components like NMOS, PMOS transistors, and Schottky diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a prior art battery equalizing circuit using an inductor and PWM control is used, then a large equalizing current can be supplied, but the equalizing current varies greatly due to temperature changes, voltage level changes, and device differences
Solution Approach 1:
The patent introduces a feedback control circuit that detects the actual equalizing current and compares it with a reference current. Based on the comparison result, the circuit dynamically adjusts the duty ratio of the PWM signal to maintain a stable equalizing current. This closed-loop feedback mechanism effectively compensates for variations caused by temperature changes, voltage level changes, and device differences, resolving the contradiction between providing large equalizing current and maintaining its stability.
2Device complexity
If the duty ratios of PWM signals are kept unchanged, then the control is simple, but the equalizing current may exceed device ratings due to influences from temperature, voltage changes, and line resistances
Solution Approach 1:
The feedback control circuit continuously monitors the equalizing current and dynamically adjusts the PWM duty ratio to prevent overcurrent conditions. This adaptive control ensures that the equalizing current remains within safe operating limits despite variations in temperature, voltage, and resistance, thereby protecting devices from damage while maintaining relatively simple control logic.
3Stability of the object's composition
If feedback control is added to maintain constant equalizing current, then current stability is improved, but the circuit complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism that, while adding some circuit elements, uses standard components and established control techniques to achieve current stability. The feedback circuit includes a current detector, comparator, and PWM controller, which are commonly available integrated circuits. This approach provides significant current stability improvement with moderate increases in circuit complexity.
Solution Approach 2:
The patent introduces a current detecting resistor as an intermediary element that converts the equalizing current into a voltage signal for feedback control. This intermediary approach allows for easy current measurement and control without directly complicating the main power transfer path, thereby achieving current stability with minimal impact on overall circuit complexity.
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 solution ensures a stable equalizing current, optimizing the balancing effect while preventing overcurrent issues, thus enhancing the performance and longevity of the battery pack.
Implementation Method 1
The feedback control circuit is connected in parallel with the current detecting resistor to detect a voltage drop across the current detecting resistor
Implementation Method 2
Through the inductor 130, energy from the battery unit 110 is transferred to the battery pack 120 or vice versa
Data Source
AI summary
The present disclosure discloses a battery equalizing circuit, which comprises a first battery unit, a second battery unit, a current detecting resistor, an equalizing inductor, a first control switch, a second control switch and a feedback control circuit. The first battery unit is connected in series with the second battery unit. The first battery unit, the current detecting resistor, the equalizing inductor and the first control switch are electrically connected with each other to form a first circuit loop. The second battery unit, the current detecting resistor, the equalizing inductor and the second control switch are electrically connected with each other to form a second circuit loop. The feedback control circuit is connected in parallel with the current detecting resistor to detect a voltage drop across the current detecting resistor, and switch between the first and the second circuit loop so as to make an equalizing current substantially constant.