Battery cell management and balance circuit, method, and battery system

A battery system comprising:

• M battery modules connected and arranged in series, each of battery modules having N battery cells connected and arranged in series;
• M×N battery cell balance circuits, each of them connecting to a battery cell of the M×N battery cells for executing a first charge or discharge command to the connected battery cell, each of the M×N battery cell balance circuits comprising:
• a fly-back converter, connected to the battery cell of the M×N battery cells;
• a discharge control portion, connected to the fly-back converter and receiving the first discharge command in a peak current control mode to enable the fly-back converter;
• and
• a charge control portion, connected to the fly-back converter and receiving the first charge command in the peak current control mode to enable the fly-back converter;
• M battery cell monitor units, each of them monitoring N battery cells of the M×N battery cells and corresponding to the N battery cell balance circuits connected to the N battery cell for generating battery cell information and the first charge or discharge commands;
• M battery module balance circuits, each of them connecting to a battery module of the M battery modules for executing charge or discharge to the entire battery module according to a second charge or discharge command;
• and
• a battery management unit connecting to the M battery cell monitor units for receiving battery cell information from each battery cell monitor unit and the M battery module balance circuits for directly or indirectly generating the second charge or discharge commands to the M battery module balance circuits;
• wherein the battery cell monitor unit of the M battery cell monitor units does not generate the first charge and discharge commands when a difference voltage value between highest and lowest monitored voltages among the N corresponding battery cell balance circuits does not reach a first threshold value;
• and
• wherein the battery management unit does not generate the second charge and discharge commands when a difference voltage value between highest and lowest monitored voltages among the M corresponding battery module balance circuits does not reach a second threshold value.

A battery cell management and balance method implemented in a battery system, the battery system having M battery modules connected and arranged in series, each of the battery modules having N battery cells connected and arranged in series, the battery cell management and balance method comprising following steps:

• (a) monitoring M×N battery cells for generating battery cell information;
• (b) generating a first charge command, a first discharge command, a second charge command and a second discharge command according to the battery cell information;
• (c) executing the first charge command and the first discharge command to a battery module of the M battery modules, each one of the battery cells of the battery module connected to a battery cell balance circuit that comprising a fly-back converter connected to the battery cell, a discharge control portion connected to the fly-back converter and receiving the first discharge command in a peak current control mode to enable the fly-back converter and a charge control portion connected to the fly-back converter and receiving the first charge command in the peak current control mode to enable the fly-back converter;
• and
• (d) executing the second charge command and the second discharge command to the M battery modules for charging or discharging the entire battery module;
• and
• (e) not generating the first charge command and the first discharge command when a difference voltage value between highest and lowest monitored voltages among N corresponding battery cell balance circuits does not reach a first threshold value and not generating the second charge command and the second discharge command when a difference voltage value between highest and lowest monitored voltages among M corresponding battery module balance circuits does not reach a second threshold value.