Auxiliary Battery Charging via Cell Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for charging auxiliary batteries in electric vehicles are inefficient due to cell imbalance and require expensive and heavy DC-DC converters, which are not necessary for low voltage batteries.
Innovation Solution
An auxiliary battery charging apparatus that uses active balancing to identify and connect cells with low depth-of-discharge from the main battery to an intermediate storage device, eliminating the need for a DC-DC converter by concurrently balancing and charging the auxiliary battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a DC-DC converter is used to recharge the low voltage auxiliary battery from the high voltage main battery, then the auxiliary battery can be recharged, but the system becomes expensive, heavy, and requires significant packaging space
Solution Approach 1:
The patent extracts the DC-DC converter from the system by using a different recharging approach. Instead of using a conventional DC-DC converter to transfer energy from the high voltage main battery to the low voltage auxiliary battery, the system uses the existing cell balancing circuitry to directly recharge the auxiliary battery from individual main battery cells, thereby eliminating the need for the complex DC-DC converter while maintaining the recharging capability
Solution Approach 2:
The patent makes the cell balancing circuitry multi-functional by using it not only for balancing the main battery cells but also for recharging the auxiliary battery. The same switching circuitry and control logic that performs cell balancing during normal operation is repurposed to transfer energy from selected main battery cells to the auxiliary battery, eliminating the need for dedicated DC-DC converter hardware
2Productivity
If cell imbalance is not addressed, then charging can proceed faster, but the useable capacity is reduced due to early termination when the weakest cell reaches its limit
Solution Approach 1:
The patent performs preliminary cell balancing actions during the charging process by continuously monitoring individual cell voltages and using the balancing circuitry to transfer energy from cells that are charging faster than others. This preliminary action prevents the formation of significant imbalances that would otherwise force early charging termination, thereby maintaining both high charging speed and maximum useable capacity
Solution Approach 2:
The patent implements feedback control by continuously monitoring the voltage of each cell in the main battery and using this information to control the switching circuitry that transfers energy between cells. The system dynamically adjusts the balancing process based on real-time cell state measurements, ensuring that charging proceeds at maximum speed while maintaining all cells within safe voltage limits to maximize useable capacity
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 enhances energy efficiency by actively balancing cells during charging, eliminating the need for a DC-DC converter, reducing weight, space, and cost, while ensuring efficient charging of low voltage batteries.
Implementation Method 1
The apparatus comprises an intermediate storage device for connection to the auxiliary battery
Implementation Method 2
The apparatus comprises a first switch unit for selectively connecting one or more of the first cells to the intermediate storage device and a second switch unit for selectively connecting one or more of said second cells to the intermediate storage device
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present disclosure relates to an auxiliary battery charging apparatus (1) for charging an auxiliary battery (3) from a main battery (4). The main battery (4) has at least a first module (5-1) including a plurality of first cells (6-1). The auxiliary battery charging apparatus (1) has an intermediate storage device (13-1) for connection to the auxiliary battery. A first switch unit (10) is provided for selectively connecting one or more of the first cells (6-1) to the intermediate storage device (3). A charging control unit (9) having an electronic processor configured to receive a first balance control signal (BAL1) for identifying one or more of said first cells (6-1) having a relatively low depth-of-discharge. During charging of the main battery (4) and in dependence on the first balance control signal (BAL1), the electronic processor is configured to output a first switch unit control signal (SW1) to control said first switch unit (10) to connect the identified one or more first cell (6-1) having a relatively low depth-of-discharge to the intermediate storage device (13-1) to charge the auxiliary battery (3). The main battery (4) can comprise at least a second module (5-2) including a plurality of second cells (6-2). The present disclosure also relates to a vehicle having an auxiliary battery charging apparatus (1); and to a method of charging an auxiliary battery (3).