Battery Control Unit Switching for Sustained Power Output
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Solution Overview
Problem
Battery systems with series-connected batteries face a reduction in the duration time for obtaining desired power due to discharge current limitations, as each battery is bypassed when it reaches a termination state, leading to frequent discharge current limitations and reduced power availability.
Innovation Solution
A battery control unit with a switching unit for each battery, a discharge current limitation unit that sets a minimum discharge current limit, and a control unit that switches batteries to a non-connection state before discharge current limitation, ensuring the minimum discharge current is not exceeded, thereby extending the duration of desired power availability without imposing discharge current limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discharge current limitation is performed on batteries when charge state becomes low, then battery deterioration is prevented, but duration time during which desired power is obtained is shortened
Solution Approach 1:
The control unit performs preliminary action by switching the battery to non-connection state before the discharge current limitation unit actually limits the discharge current. This anticipatory switching prevents the harmful effect of discharge current limitation while still protecting the battery, thereby extending the duration time for obtaining desired power without causing deterioration.
2Productivity
If a battery reaching discharge termination state is bypassed and disconnected, then charging and discharging can continue in other batteries, but discharge current limitation is frequently imposed which reduces power availability
Solution Approach 1:
The control unit switches the battery to non-connection state in advance before the discharge current limitation is imposed, based on predicted future battery states. This preliminary switching allows the system to maintain higher power availability by avoiding frequent discharge current limitations, while still enabling continued operation of other batteries in the series-connected system.
Data Source
AI summary
A battery control unit includes a switching unit, a system controller, and a control unit. The switching unit switches between a connection state in which the corresponding battery is discharged and a non-connection state in which the corresponding battery is not discharged. The system controller limits a discharge current flowing through the battery in the connection state so as not to exceed a minimum discharge current limitation value that is smallest among discharge current limitation values. The control unit switches to the non-connection state in order from the battery having the minimum discharge current limitation value before the discharge current limitation unit limits the discharge current. Further, the control unit switches all the batteries to the connection state after the batteries in the connection state becomes one, and then switch the battery to the non-connection state in order from the battery determined to reach a discharge termination state.