Battery Pack Balancing via Dynamic Switch Control
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Solution Overview
Problem
Existing battery cell balancing methods result in high leak currents, leading to efficiency degradation and power losses in battery packs, as they activate switches for equalization, which is not optimally managed in current systems.
Innovation Solution
A method and system that selectively control controllable switches connected to resistors in parallel with battery cells to initiate discharging, using a control unit to minimize current losses by defining and optimizing a control variable that reduces power losses and improves balance, with a cost function approach to determine the most efficient switching strategy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If battery cell balancing is performed by activating switches to discharge selected cells through resistors, then cell voltage balance is improved, but leak currents increase causing power losses and efficiency degradation
Solution Approach 1:
The patent implements dynamic control of balancing switches based on real-time cell voltage measurements and state of charge estimates. The control unit continuously adjusts which switches are activated and for how long, transitioning from static to dynamic switching strategies. This allows the system to minimize leak currents by only activating switches when and where needed, rather than maintaining continuous discharge paths.
Solution Approach 2:
The patent changes the control parameters from simple on/off switch control to optimized switching duration and sequence based on cell voltage differences and state of charge. By adjusting the timing and duration of switch activation, the system achieves cell balancing while minimizing energy loss. The control unit modifies switching parameters dynamically based on measured cell characteristics.
2Duration of action of stationary object
If continuous cell balancing is implemented to maintain optimal battery performance, then battery lifespan and energy capacity are extended, but system complexity and control requirements increase
Solution Approach 1:
The patent implements a self-service balancing system where the control unit automatically monitors cell voltages, estimates state of charge, and activates balancing switches without external intervention. The system uses its own measured data to make balancing decisions, eliminating the need for complex external control mechanisms. Each cell's balancing needs are addressed autonomously based on real-time conditions.
Solution Approach 2:
The patent incorporates feedback loops where cell voltage measurements and state of charge estimates continuously inform switching decisions. The control unit monitors the效果 of balancing actions and adjusts subsequent switching strategies accordingly. This closed-loop feedback mechanism simplifies control by using measured data to automatically determine when and how to activate balancing switches.
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
This approach minimizes power losses due to leak currents, enhances the performance and energy capacity of battery packs, and extends their lifespan, while being implemented with inexpensive hardware and software, allowing for continuous balancing.
Implementation Method 1
a resistor which is connected in parallel with said battery cell... initiate discharging of the corresponding battery cell
Data Source
AI summary
A method is provided for balancing a battery pack including a plurality of battery cells connected in series, wherein each battery cell is associated with a resistor which is connected in parallel with the battery cell and wherein each of the resistors is coupled in series with a controllable switch which is connected to a control unit. The method includes selectively closing and opening the switch so as to initiate discharging of the corresponding battery cell, thereby balancing the battery cell in relation to other cells of the battery pack. Furthermore, the method includes a) defining a control variable indicating, for each switch, an open or closed condition, b) determining a cost based at least on the current losses of the battery pack resulting from the switch being controlled according to the control variable, repeating steps a) and b) a predefined number of times, d) selecting a control variable which results in the cost being minimized, and e) initiating the balancing based on the selected control variable. A system for balancing a battery pack is also provided.