BMS 电池管理系统技术探析--控制篇
1.
控制概略
针对混合动力、纯电动及不间断电源,有很多控制方案,选择什么方案主要取决于成本控制,也许还
有设计者的设计习惯。
There are various solutions of control to hybrid , electric vehicle and uninterrupt power supply system.
Selecting of solution,perhaps affected by habit of its designer, depends mainly on the cost.
无论应用于何处,两个基本控制是必不可少的:放电控制和充电控制。当电池状况正常时,放电控制
保证放电回路接通,充电控制保证充电回路接通。当电池出现异常时,根据异常情况作出是切断充电回路
还是切断放电回路。
Wherever application is, two basic controls are inexpensible: discharge control and charge control. When
battery is ok, discharge control guarantees the discharging circuit is on, and charge control guarantees charging
circuit is on. When something is wrong with the battery, action should be taken to cut off charging circuit or
discharging circuit.
一般情况下,当发生单体欠压、或电池温度过高时、或电流过大,要切断放电回路。而当单体过压、
或电池温度过高或过低、或者电流过大时都要切断充电回路。
Generally, when Cell Voltage is over low, or battery temperature is over high, or discharging current is over
high, the discharging circuit should be cut off. When Cell Voltage is over high, or battery temperature is over high,
or over low, or charging current is over high, the charging circuit should be cut off.
在车载应用场合,将充电、放电控电合并一起来进行控制是可以的,这样可以省去一个继电器,因为
大功率继电器还是比较昂贵的。但在 UPS 应用中,充放电控制必须分开。
For solutions to vehicle, Charge control and discharge control can be multiplexed in order to save one
contactor, usually, high power contactor is very expensive. But in UPS application, charge control and discharge
control should be seperated.
实际上,一旦电压越过充电或放电门槛,导致电路被切断。充放电回路被切断后,电压一般较快的恢
复到正常值。一旦电压回到正常值,接触器会重新接通。接触器在切断和接通之间频繁动作会缩短接触器
寿命,所以一般都设定一定的回滞电压,以避免接触器在切断和接通之间频繁动作。当充电控制和放电控
制合并一块时,一旦发生过充而导致电路被切断后,此时希望能够放电也是不可能的,因为充放电经由同
一个继电器,这显然听起来很不合理。反之亦然,当发生过放而导致电路被切断后,此时想充电也是不可
能。这就发生死锁的情况,死锁情况下可以通过切断控制模块的电源,使得控制回到初态,重新接通电路。
在车上,可以通过关掉钥匙重新打到 ON 档实现。但 UPS 是没有人看护的,死锁无法解除。所以在车辆应
用中可以将充放电合在一起,而在 UPS 中就不能这么做。
In fact, once the voltage passes over the threshold, the circuit will be cut off. After circuit is cut off, voltage
will goes back. Once the voltage goes normal, contactor will be on again. The frequent shuffling between ON and
OFF leads to shortening life of contactor. So
hysteresis has been used to avoid frequent shuffling. When charge
and discharge control has been unified. Once over-charging happens, which leads to cutting-off of circuit,
attempts to discharging becomes impossible because charge and discharge share the common contactor.
Vice versa, charge becomes impossible when over-discharge happens which results in cutting of contactor.
This is so-called deadlock. When deadlock happens, it can be solved by powering off BMS control module via
vehicle key. But in UPS, BMS runs unattendently, deadlock can
’t be broken. Therefore, in UPS, charge and
discharge should be controlled separately.