Modular Voltage Balancing Networks for Series Connected Battery Cells

• Author / Creator

  Atrin Tavakoli

• Battery cells are an emerging technology for storage in electrical vehicle, industrial and
  residential applications has become more popular. To meet the high voltage and power,
  battery cells are connected in series and parallel. Series connected battery cells share the
  same charge/discharge current. Therefore, in the case of characteristic mismatch between
  battery cells, a battery cell may be over-charged or overly-discharged. These conditions
  are two reasons that decrease the life-time and affect the performance of battery cells. All
  of these challenges can be tackled using battery voltage balancer circuits. These circuits
  can improve the performance, life-time of battery cells and reduce the maintenance and
  replacement cost of the battery cells.
  Three battery voltage balancer circuits along with their control methods are described.
  The proposed methods are modular topologies where every two battery cells are connected
  to a single balancer circuit bridge/module. These bridges/modules are connected through
  inter-bridge/module windings. These circuits are based on various types of Buck-Boost
  and SEPIC converters and are modular, easy to implement, low-cost and, have low
  number of components. The first and second methods offer ZCS in turn ON. Moreover,
  the proposed methods are shown to be faster than the existing methods. The faster
  equalization speed is due to the ability of these circuits to exchange charge between all
  battery cells at the same time in each switching cycle.
  The proposed distributed controllers require each bridge to monitor its own battery
  cell voltages and also those of the adjacent bridges. This reduces the number of feedback
  sensors. Detailed analysis is presented that quantifies the flow of charge between a
  number of series connected battery cells. Comprehensive design procedures based on
  circuit analysis are presented for all proposed circuits which guarantee a fixed switching
  frequency and zero current switching. Also, the proposed controllers limit the current in
  the system without using any current sensors. Analytical, simulation and experimental
  results are presented to verify the effectiveness of the proposed methods.

• Subjects / Keywords

  • Low Power Converters
  • Control of Power Converter
  • Battery

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-kn1v-0558

• License

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