BMS电池管理系统技术探析--控制篇

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 V oltage is over low, or battery temperature is over high, or discharging current is over high, the discharging circuit should be cut off. When Cell V oltage 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.图14-1 控制电路接口Fig.14-1 Interface of Control Circuit控制电路如图14-1所示，在早期的产品中，当电池状态正常时，Q 是断开的，此时Bp 和N1/N2/N3/N4的电压相等，均为电源电压。

反之，当电池状态异常时，Q 导通，此时N1/N2/N3/N4对地导通，此时Bp 为电源电压，而N1/N2/N3/N4的电压小于1V 。

这种控制方法的缺点是，当模块没有供电时，Q 也是断开的，此时如果电池异常，控制失去保护作用。

现代产品中，控制策略反过来了，即电池状况正常时，Q 是导通的，反之，Q 断开。

当模块没有供电时，Q 一定是断开的。

The control circuit is illustrated in Fig.14-1. In early produc, when battery is ok, Q turns off, the voltage of N1/N2/N3/N4 is equal to voltage of Bp which is the power supply, otherwise, ie battery is abnormal, Q turns on, he voltage of N1/N2/N3/N4 is under 1V. The shortcoming of this control is that when module powers down, Q remains OFF. In such circumstance, if battery is abnormal, protection is invalid. In Modern BMS, method of control has been corrected. When battery is normal, Q keeps ON, otherwise, it keeps OFF. When module has no power supply, Q keeps OFF.每个输出的功能是由参数决定的.如图14-2所示，在参数表8的位置0填决定N1功能的控制码，在参数表8的位置1填决定N2功能的控制码。

填写正确的模块编号，点击取参数按钮，可以查看参数值.控制码列表如下：The function of each output is defined by parameters. The function of N1 is determined by function code stored in position 0 of parameter table 8(Param No. 8 in Fig.14-2). The function of N2 is determined by function code stored in position 1 of parameter table 8(Param No. 8 in Fig.14-2). Fill the correct Module No. you can fetch parameter from the module. The function codes are listed below:1— SOC 状态/the state of SOC2— 电池状态/The state of Battery3— 充放电总控/Charge/Discharge Control, when nothing wrong, output has been driven to ground.4— 过放保护/Discharge Protect, when something wrong during discharge, output has been driven toground5— 过充保护/Charge Protect , when something wrong during charge, output has been driven to ground 6— 限功输出/Restricted load control7— 风扇控制/Fan to cool battery8— 自动充电控制/Auto-charge control. Auto charge will be triggered when certain time passes or SOC goeslow.9— 保留reserved10— 保留reserved11— 保留reserved12— 过放保护，与功能4相反/Discharge Protect contrary to function 4, when nothing wrong duringdischarge, output has been driven to ground13— 过充保护，与功能5相反/Discharge Protect contrary to function 5, when nothing wrong duringdischarge, output has been driven to ground图14-2 输出控制码Fig.14-2 Control Code for Output14— 保留reserved15— 保留reserved16— 保留reserved17— 预充控制/Precharge2. 车载控制策略/Solutions to Vehicle车载控制又分混动和纯电控制。