适用于大功率电池组的电池管理架构
汽车和工业设备制造商一般要求电池寿命超过 10 年，这些制造商还会规定所需的可用电池容量。对于电池系统设计师来说，挑战就是如何用最小的电池组实现最大的容量。为了实现这个目标，电池系统必须用精准的电子组件仔细控制和监视电池。
Vehicle and industrial equipment manufacturers typically demand battery lifetimes exceeding ten years, and they also specify the required usable battery capacity. The challenge to the battery system designer is to squeeze the maximum capacity out of the smallest battery pack. To accomplish this, the battery system must carefully control and monitor the batteries using precision electronics.
大功率电池组系统
High Power Battery Pack Systems
用于电动汽车或工业设备的大功率电池组系统由很多串联叠置的电池组成。一个典型的电池组含有的电池可能有 96 个之多，就充电至 4.2V 的锂离子电池而言，总共能产生超过 400V 的电压。
High power battery pack systems used for electric vehicles or industrial equipment consist of dozens of batteries stacked in series. A typical pack might have a stack of 96 batteries, developing a total voltage in excess of 400V for Li-ion batteries charged to 4.2V.
尽管系统将电池组看作单个高压电池，对电池组中的电池同时充电或放电，但是电池控制系统必须独立考虑每一个电池的状态。如果电池组中一个电池的容量比其他电池略低，那么经过多个充电/放电周期之后，其充电状态 (SOC) 将逐渐偏离其余的电池。如果这节电池与其余电池的充电状态没有周期性地进行均衡，那么该电池最终将进入深度放电状态，从而损坏，并最终导致电池组故障。因此，必须监视每节电池的电压，以确定充电状态。此外，还必须预先采取措施，使电池能单独充电或放电，以均衡电池之间的充电状态。
While the system sees the battery pack as a single, high-voltage battery – charging and discharging the entire battery pack at once – the battery control system must consider each battery’s condition independently. If one battery in a stack has slightly less capacity than the other batteries, then its SOC (state of charge) will gradually deviate from the rest of the batteries over multiple charge/discharge cycles.
If that cell’s SOC is not periodically balanced with the rest of the batteries, then it will eventually be driven into deep discharge, leading to damage, and eventually complete battery stack failure. Thus, each cell’s voltage must be monitored to determine state of charge. In addition, there must be a provision for cells to be individually charged or discharged to balance their SOCs.
与监视系统通信
Communication with the Monitoring System
电池组监视系统需要考虑的一个重要因素是通信接口。就印刷电路板 (PCB) 内部的通信而言，常见的选择包括串行外围接口 (SPI) 总线和内置集成电路 (I2C) 总线。这两种接口的通信开销都很低，适合于低干扰环境。
An important consideration for the battery-pack-monitoring system is the communications interface. For communication within a PCB (printed circuit board), common options include the serial peripheral interface (SPI) bus and inter-integrated circuit (I2C) bus. Each has low communications overhead, suitable for low-interference environments.
另一种选择是 CAN 总线，该接口在汽车应用中得到了广泛采用。CAN 总线非常可靠，具有差错检测和容错能力，但是通信开销很大，材料成本很高。尽管从电池系统到主 CAN 总线有一个接口也许是可取的，但在电池组内部，SPI 或 I2C 通信是有利的。
Another option is the CAN bus, which has widespread use in vehicle applications. The CAN bus is very robust, with error detection and fault tolerance, but it carries significant communications overhead and high materials cost. While an interface from the battery system to the main CAN bus may be desirable, SPI or I2C communications can be advantageous within the battery pack.
诸如凌力尔特的 LTC6802 电池组监视器 IC 等器件测量由多达 12 节电池组成的电池组的电压，多个 LTC6802可以从电池组的低端到顶端串联叠置，该器件还有内部开关，允许单节电池放电，以使该电池与电池组中其余电池的容量达到均衡状态。
Devices such as the LTC6802 battery stack monitor IC from Linear Technology measure the voltages of up to 12 stacked cells. Multiple LTC6802s can be stacked in series from the bottom to the top of the battery stack. The device also has internal switches that provide for the discharge of individual cells to bring them into balance with the rest of the stack.
为了说明这种电池组架构，我们考虑一个有 96 节锂离子电池的系统。监视整个电池组需要 8 个电池组 IC，每个器件都以不同的电压工作。
To illustrate the battery stack architecture, consider a system with 96 Li-ion cells. Eight battery-stack ICs would be required to monitor the entire stack, with each device operating at different voltage levels.
采用 4.2V 锂离子电池，底端监视器件监视 12 个电池，电压从 0V 至 50.4V。下一组电池的电压范围为 50.4V 至 100.8V，沿着电池组向上依此类推。
Using 4.2V Li-ion batteries, the bottom-monitoring device would straddle 12 batteries with potentials scaling from 0V to 50.4V. The next group of batteries would have voltages ranging from 50.4V to 100.8V, and so forth, up the stack.
这些器件以不同的电压工作，它们之间的通信带来了巨大挑战。人们已经考虑了各种方法，考虑到系统设计师的侧重点不同，每种方法都有各自的优点和缺点。
Communicating between these devices, at different potentials, presents a difficult challenge. A variety of approaches have been considered, and each has advantages and disadvantages in light of the priorities of the system designers.
电池监视的要求
Battery-Monitoring Requirements
在确定电池监视系统的架构时，至少需要均衡 5 个主要的要求。这些要求的相对重要性视最终客户的需求和期望的不同而不同。
At least five major requirements need to be balanced when deciding between battery-monitoring-system architectures. Their relative importance depends on the needs and expectations of the end customer.
1. 准确度：为了充分利用最大的电池容量，电池监视器必须是准确的。不过，汽车和工业系统充满噪声，电磁干扰存在于很宽的频率范围内。准确度有任何损失都将给电池组的寿命和性能带来负面影响。
1. Accuracy: To take advantage of the maximum possible battery capacity, the battery monitor needs to be accurate. Vehicles and industrial systems, however, are noisy, with electromagnetic interference over a wide range of frequencies. Any loss of accuracy will adversely affect battery pack longevity and performance.
2. 可靠性：无论使用什么样的电源，汽车和工业制造商都必须满足极高的可靠性标准。此外，某些电池的高能量容量和潜在的易变性也是主要的安全隐忧。在保守条件下停机的故障保险系统比较适合灾难性电池故障，尽管这种系统有可能不幸使乘客滞留或使生产线暂停。因此，电池系统必须仔细监视和控制，以确保在系统的整个寿命期内实现全面控制。为了最大限度地减少虚假和真实故障，一个良好设计的电池组系统必须保证可靠的通信、采用可最大限度地减少故障的模式、和具备故障检测。
2. Reliability: Automotive and industrial manufacturers must meet extremely high reliability standards, irrespective of the power source. Furthermore, the high energy capacity and potentially volatile nature of some battery technologies is a major safety concern. A fail-safe system that shuts down under conservative conditions is preferable to catastrophic battery failure, although it has the unfortunate potential of stranding passengers or bringing a manufacturing line to a halt. As a result, battery systems must be carefully monitored and controlled to ensure complete control over their entire life in the system. To minimize both false and real failures, a well-designed battery pack system must have robust communications, minimized failure modes, and fault detection.
3. 可制造性：新式汽车中含有种类繁多的电子组件和复杂的布线线束。增加复杂的电子组件和配线以支持电动汽车 / 混合电动汽车 (EV/HEV) 电池系统会给汽车制造带来更多挑战。必须最大限度地减少组件和连线，以满足严格的尺寸和重量限制，并确保大批量生产是实际可行的。
3. Manufacturability: Modern vehicles already contain a vast array of electronics with complicated wiring harnesses. Adding sophisticated electronics and wiring to support an EV/HEV (electric vehicle/hybrid electric vehicle) battery system provides an additional challenge for automobile manufacturing. The total number of components and connections must be minimized to meet stringent size and weight constraints and ensure that high-volume production is practical.
4. 成本：复杂的电子控制系统可能很昂贵。最大限度地减少相对昂贵的组件 (如微控制器、接口控制器、电流隔离器和晶体) 可以显著降低系统的总体成本。
4. Cost: Complicated electronic control systems can be expensive. Minimizing the number of relatively costly components, such as microcontrollers, interface controllers, galvanic isolators, and crystals, can significantly reduce total system cost.
5. 功率：电池监视器本身也是电池的负载。较低的工作电流可提高系统效率，而当汽车或设备关闭时，较低的备用电流可防止电池过度放电。
5. Power: The battery monitor itself is a load on the batteries. Lower active current improves system efficiency, and lower standby current prevents excessive battery discharge when the vehicle or equipment is off.
电池监视
Battery Monitoring
下面介绍了电池监视系统的 4 种架构。每种架构都设计为自主电池监视系统，并假定系统由 96 个电池组成，12 个电池为一组，分成 8 组 (见表 1)。每组都有一个至主 CAN 总线的 CAN 接口，而且与系统其余部分是电流隔离的。
Four architectures for battery-monitoring systems are described below. Each architecture is designed to be an autonomous battery-monitoring system and assumes a 96-battery system organized into 8 groups of 12 batteries (see Table 1). Each provides a CAN interface to the main CAN bus and is galvanically isolated from the rest of the system.
表 1：电池监视架构比较
并行独立 CAN 模块 具 CAN 网关的并行模块 具 CAN 网关的单个监视模块 具 CAN 网关的串行模块
准确性 +
LTC6802 在电池模块内部 +
LTC6802 在电池模块内部 –
敏感的模拟导线布在单个电路板上 +
LTC6802 在电池模块内部
可靠性 +
CAN 通过电缆提供坚固的通信，但是额外的电路系统导致故障率提高 +
SPI 接口不如通过电缆连接的 CAN 坚固，但是并行通信最大限度减小负面影响 + +
通信在单块电路板内，从而最大限度地减少了电缆连接和对通信干扰的灵敏度 –
SPI 接口的坚固性不如采用电缆的 CAN
可制造性 –
需要大量并行通信配线 –
需要大量并行通信配线 –
单块精密电路板，但是模拟灵敏度可能带来配线难题 +
在模块之间的串行通信配线
成本 – –
每个模块中都有微控制器、CAN 接口和隔离，加上一块主控制器电路板 –
单个微控制器和 CAN 收发器，但是有具数字隔离器的 精密 PC 板 + +
单个微控制器、CAN 收发器和隔离器，在一块精密 PC 板上 +
单个微控制器、CAN 收发器和隔离器，但是有单独的精密 PC 板
功率 – –
多个微控制器和 CAN 接口需要过大的功耗 –
高速数字隔离器具极大的电流消耗 + +
具低功率 SPI 接口的最小电路系统 +
最小电路系统，但 SPI 接口需要更多功率以在电路板之间通信
并联独立 CAN 模块 (图 1)
Parallel Independent CAN Modules (Figure 1)
每个由 12 个电池组成的模块都含有一个 PC 板，板上有1个 LTC6802、1个微控制器、1个 CAN 接口和1个电流隔离变压器。系统所需的大量电池监视数据使主 CAN 总线难以应付，因此 CAN 模块必须在 CAN 子网上。CAN 子网由一个主控制器协调，该主控制器也为主 CAN 总线提供网关。
Each 12-battery module contains a PC board with an LTC6802, a microcontroller, a CAN interface, and a galvanic isolation transformer. The large amount of battery-monitoring data required for the system would overwhelm the main CAN bus, so the CAN modules need to be on local CAN subnets. The CAN subnets are coordinated by a master controller that also provides the gateway to the main CAN bus.
图 1 并联独立 CAN 模块
具 CAN 网关的并联模块 (图 2)
Parallel Modules with CAN Gateway (Figure 2)
每个由 12 节电池组成的模块都含有一个 PC 板，板上有一个 LTC6802 和一个数字隔离器。这些模块具有至控制器电路板的独立接口连接，该控制器电路板上含有1个微控制器、1个 CAN 接口和1个电流隔离变压器。微控制器协调这些模块，并为主 CAN 总线提供网关。
Each 12-battery module contains a PC board with an LTC6802 and a digital isolator. The modules have independent interface connections to a controller board containing a microcontroller, a CAN interface, and a galvanic isolation transformer. The microcontroller coordinates the modules and provides the gateway to the main CAN bus.
图 2：具 CAN 网关的并联模块的方框图
Digital Isolator：数字隔离器
具 CAN 网关的单个监视模块 (图 3)
Single Monitoring Module with CAN Gateway (Figure 3)
在这种配置中，由 12 节电池组成的模块中没有监视和控制电路。取而代之的是，单个 PC 板含有 8 个 LTC6802 监视器 IC，每个监视器 IC 都连接至其电池模块。LTC6802 器件通过非隔离式 SPI 兼容的串行接口通信。单个微控制器通过 SPI 兼容的串行接口控制整组电池监视器，该微控制器也是至主 CAN 总线的网关。CAN 收发器和电流隔离变压器是该电池监视系统的最后两个组件。
In this configuration, there is no monitoring and control circuitry within the 12-battery modules. Instead, a single PC board has eight LTC6802 monitor ICs, each of which is connected to its battery module. The LTC6802 devices communicate through non-isolated SPI-compatible serial interfaces. A single microcontroller controls the entire stack of battery monitors via the SPI-compatible serial interface, and it also is the gateway to the main CAN bus. A CAN transceiver and a galvanic isolation transformer complete the battery-monitoring system.
图 3：具 CAN 网关的单个监视模块的方框图
Monitoring Module：监视模块
具 CAN 网关的串联模块 (图 4)
Series Modules with CAN Gateway (Figure 4)
这种架构类似于单个监视模块，除了每个 LTC6802 都在由 12 个电池组成的模块内部的 PC 板上。8 个模块通过 LTC6802 非隔离式 SPI 兼容串行接口通信，这在电池模块之间需要连接 3 或 4 条传导电缆。单个微控制器通过底端监视器 IC 控制整组电池监视器，并作为至主 CAN 总线的网关。CAN 收发器和电流隔离变压器仍然是电池监视系统的最后两个组件。
This architecture is similar to the single monitoring module, except each LTC6802 is on a PC board within its 12-battery module. The eight modules communicate through the LTC6802 non-isolated SPI-compatible serial interface, which requires a three- or four-conductor cable to be connected between pairs of battery modules.
A single microcontroller controls the entire stack of battery monitors via the bottom monitor IC, and also acts as the gateway to the main CAN bus. Once again, a CAN transceiver and a galvanic isolation transformer complete the battery-monitoring system.
图 4：具 CAN 网关的串联模块的方框图
电池监视架构选择
Battery-Monitoring Architecture Selection
第一种和第二种架构一般而言比较具有挑战性，因为并行接口需要大量连接和外部隔离。为了应对这种复杂性的提高，设计师采用了独立地与每个监视器器件通信的方法。第三种 (具 CAN 网关的单个监视模块) 和第四种 (具 CAN 网关的串联模块) 架构采用了简化的方法，所受限制最少。
The first and second architectures are generally challenging due to the significant number of connections and the external isolation required for the parallel interface. For this added complexity, the designer has independent communication to each monitor device. The third (single monitoring module with CAN gateway) and fourth (series modules with CAN gateway) architectures are simplified approaches with minimal limitations.
LTC6802 可以满足所有 4 种配置的需求，为系统设计师留出了选择余地。该器件的两个变体也已开发出来，一个用于串联配置，另一个用于并联配置。LTC6802-1 用于叠置式 SPI 接口配置。多个器件可以通过一个接口串联连接，该接口无需外部电平移位器或隔离器，就可沿着电池组来回发送数据。LTC6802-2 允许用单个器件满足并联架构的需求。两种变体有相同的电池监视性能规格和功能。
The LTC6802 can address all four configurations, leaving the choice to the system designer. Two variants of the device have been created, one for series configurations and one for parallel configurations. The LTC6802-1 is designed for use in a stacked SPI interface configuration. Multiple devices can be connected in series through an interface that sends data up and down the battery stack without external level shifters or isolators. The LTC6802-2 allows individual device addressing in parallel architectures. Both variants have the same battery-monitoring specifications and capabilities.
电动汽车和大功率工业设备向电池组提出了大量要求。制造商期望用经济实惠的电池系统满足严格的可靠性要求。最新的电池监视 IC 使系统设计师能在无性能折衷的前提下，灵活地选择最佳电池组架构。
Electric vehicles and high-power industrial equipment place huge demands on battery packs. Manufacturers expect cost-effective battery systems that meet their stringent reliability requirements. The latest battery-monitoring ICs give system designers the flexibility to choose the best battery pack architecture without compromising performance.
Vehicle and industrial equipment manufacturers typically demand battery lifetimes exceeding ten years, and they also specify the required usable battery capacity. The challenge to the battery system designer is to squeeze the maximum capacity out of the smallest battery pack. To accomplish this, the battery system must carefully control and monitor the batteries using precision electronics.
大功率电池组系统
High Power Battery Pack Systems
用于电动汽车或工业设备的大功率电池组系统由很多串联叠置的电池组成。一个典型的电池组含有的电池可能有 96 个之多，就充电至 4.2V 的锂离子电池而言，总共能产生超过 400V 的电压。
High power battery pack systems used for electric vehicles or industrial equipment consist of dozens of batteries stacked in series. A typical pack might have a stack of 96 batteries, developing a total voltage in excess of 400V for Li-ion batteries charged to 4.2V.
尽管系统将电池组看作单个高压电池，对电池组中的电池同时充电或放电，但是电池控制系统必须独立考虑每一个电池的状态。如果电池组中一个电池的容量比其他电池略低，那么经过多个充电/放电周期之后，其充电状态 (SOC) 将逐渐偏离其余的电池。如果这节电池与其余电池的充电状态没有周期性地进行均衡，那么该电池最终将进入深度放电状态，从而损坏，并最终导致电池组故障。因此，必须监视每节电池的电压，以确定充电状态。此外，还必须预先采取措施，使电池能单独充电或放电，以均衡电池之间的充电状态。
While the system sees the battery pack as a single, high-voltage battery – charging and discharging the entire battery pack at once – the battery control system must consider each battery’s condition independently. If one battery in a stack has slightly less capacity than the other batteries, then its SOC (state of charge) will gradually deviate from the rest of the batteries over multiple charge/discharge cycles.
If that cell’s SOC is not periodically balanced with the rest of the batteries, then it will eventually be driven into deep discharge, leading to damage, and eventually complete battery stack failure. Thus, each cell’s voltage must be monitored to determine state of charge. In addition, there must be a provision for cells to be individually charged or discharged to balance their SOCs.
与监视系统通信
Communication with the Monitoring System
电池组监视系统需要考虑的一个重要因素是通信接口。就印刷电路板 (PCB) 内部的通信而言，常见的选择包括串行外围接口 (SPI) 总线和内置集成电路 (I2C) 总线。这两种接口的通信开销都很低，适合于低干扰环境。
An important consideration for the battery-pack-monitoring system is the communications interface. For communication within a PCB (printed circuit board), common options include the serial peripheral interface (SPI) bus and inter-integrated circuit (I2C) bus. Each has low communications overhead, suitable for low-interference environments.
另一种选择是 CAN 总线，该接口在汽车应用中得到了广泛采用。CAN 总线非常可靠，具有差错检测和容错能力，但是通信开销很大，材料成本很高。尽管从电池系统到主 CAN 总线有一个接口也许是可取的，但在电池组内部，SPI 或 I2C 通信是有利的。
Another option is the CAN bus, which has widespread use in vehicle applications. The CAN bus is very robust, with error detection and fault tolerance, but it carries significant communications overhead and high materials cost. While an interface from the battery system to the main CAN bus may be desirable, SPI or I2C communications can be advantageous within the battery pack.
诸如凌力尔特的 LTC6802 电池组监视器 IC 等器件测量由多达 12 节电池组成的电池组的电压，多个 LTC6802可以从电池组的低端到顶端串联叠置，该器件还有内部开关，允许单节电池放电，以使该电池与电池组中其余电池的容量达到均衡状态。
Devices such as the LTC6802 battery stack monitor IC from Linear Technology measure the voltages of up to 12 stacked cells. Multiple LTC6802s can be stacked in series from the bottom to the top of the battery stack. The device also has internal switches that provide for the discharge of individual cells to bring them into balance with the rest of the stack.
为了说明这种电池组架构，我们考虑一个有 96 节锂离子电池的系统。监视整个电池组需要 8 个电池组 IC，每个器件都以不同的电压工作。
To illustrate the battery stack architecture, consider a system with 96 Li-ion cells. Eight battery-stack ICs would be required to monitor the entire stack, with each device operating at different voltage levels.
采用 4.2V 锂离子电池，底端监视器件监视 12 个电池，电压从 0V 至 50.4V。下一组电池的电压范围为 50.4V 至 100.8V，沿着电池组向上依此类推。
Using 4.2V Li-ion batteries, the bottom-monitoring device would straddle 12 batteries with potentials scaling from 0V to 50.4V. The next group of batteries would have voltages ranging from 50.4V to 100.8V, and so forth, up the stack.
这些器件以不同的电压工作，它们之间的通信带来了巨大挑战。人们已经考虑了各种方法，考虑到系统设计师的侧重点不同，每种方法都有各自的优点和缺点。
Communicating between these devices, at different potentials, presents a difficult challenge. A variety of approaches have been considered, and each has advantages and disadvantages in light of the priorities of the system designers.
电池监视的要求
Battery-Monitoring Requirements
在确定电池监视系统的架构时，至少需要均衡 5 个主要的要求。这些要求的相对重要性视最终客户的需求和期望的不同而不同。
At least five major requirements need to be balanced when deciding between battery-monitoring-system architectures. Their relative importance depends on the needs and expectations of the end customer.
1. 准确度：为了充分利用最大的电池容量，电池监视器必须是准确的。不过，汽车和工业系统充满噪声，电磁干扰存在于很宽的频率范围内。准确度有任何损失都将给电池组的寿命和性能带来负面影响。
1. Accuracy: To take advantage of the maximum possible battery capacity, the battery monitor needs to be accurate. Vehicles and industrial systems, however, are noisy, with electromagnetic interference over a wide range of frequencies. Any loss of accuracy will adversely affect battery pack longevity and performance.
2. 可靠性：无论使用什么样的电源，汽车和工业制造商都必须满足极高的可靠性标准。此外，某些电池的高能量容量和潜在的易变性也是主要的安全隐忧。在保守条件下停机的故障保险系统比较适合灾难性电池故障，尽管这种系统有可能不幸使乘客滞留或使生产线暂停。因此，电池系统必须仔细监视和控制，以确保在系统的整个寿命期内实现全面控制。为了最大限度地减少虚假和真实故障，一个良好设计的电池组系统必须保证可靠的通信、采用可最大限度地减少故障的模式、和具备故障检测。
2. Reliability: Automotive and industrial manufacturers must meet extremely high reliability standards, irrespective of the power source. Furthermore, the high energy capacity and potentially volatile nature of some battery technologies is a major safety concern. A fail-safe system that shuts down under conservative conditions is preferable to catastrophic battery failure, although it has the unfortunate potential of stranding passengers or bringing a manufacturing line to a halt. As a result, battery systems must be carefully monitored and controlled to ensure complete control over their entire life in the system. To minimize both false and real failures, a well-designed battery pack system must have robust communications, minimized failure modes, and fault detection.
3. 可制造性：新式汽车中含有种类繁多的电子组件和复杂的布线线束。增加复杂的电子组件和配线以支持电动汽车 / 混合电动汽车 (EV/HEV) 电池系统会给汽车制造带来更多挑战。必须最大限度地减少组件和连线，以满足严格的尺寸和重量限制，并确保大批量生产是实际可行的。
3. Manufacturability: Modern vehicles already contain a vast array of electronics with complicated wiring harnesses. Adding sophisticated electronics and wiring to support an EV/HEV (electric vehicle/hybrid electric vehicle) battery system provides an additional challenge for automobile manufacturing. The total number of components and connections must be minimized to meet stringent size and weight constraints and ensure that high-volume production is practical.
4. 成本：复杂的电子控制系统可能很昂贵。最大限度地减少相对昂贵的组件 (如微控制器、接口控制器、电流隔离器和晶体) 可以显著降低系统的总体成本。
4. Cost: Complicated electronic control systems can be expensive. Minimizing the number of relatively costly components, such as microcontrollers, interface controllers, galvanic isolators, and crystals, can significantly reduce total system cost.
5. 功率：电池监视器本身也是电池的负载。较低的工作电流可提高系统效率，而当汽车或设备关闭时，较低的备用电流可防止电池过度放电。
5. Power: The battery monitor itself is a load on the batteries. Lower active current improves system efficiency, and lower standby current prevents excessive battery discharge when the vehicle or equipment is off.
电池监视
Battery Monitoring
下面介绍了电池监视系统的 4 种架构。每种架构都设计为自主电池监视系统，并假定系统由 96 个电池组成，12 个电池为一组，分成 8 组 (见表 1)。每组都有一个至主 CAN 总线的 CAN 接口，而且与系统其余部分是电流隔离的。
Four architectures for battery-monitoring systems are described below. Each architecture is designed to be an autonomous battery-monitoring system and assumes a 96-battery system organized into 8 groups of 12 batteries (see Table 1). Each provides a CAN interface to the main CAN bus and is galvanically isolated from the rest of the system.
表 1：电池监视架构比较
并行独立 CAN 模块 具 CAN 网关的并行模块 具 CAN 网关的单个监视模块 具 CAN 网关的串行模块
准确性 +
LTC6802 在电池模块内部 +
LTC6802 在电池模块内部 –
敏感的模拟导线布在单个电路板上 +
LTC6802 在电池模块内部
可靠性 +
CAN 通过电缆提供坚固的通信，但是额外的电路系统导致故障率提高 +
SPI 接口不如通过电缆连接的 CAN 坚固，但是并行通信最大限度减小负面影响 + +
通信在单块电路板内，从而最大限度地减少了电缆连接和对通信干扰的灵敏度 –
SPI 接口的坚固性不如采用电缆的 CAN
可制造性 –
需要大量并行通信配线 –
需要大量并行通信配线 –
单块精密电路板，但是模拟灵敏度可能带来配线难题 +
在模块之间的串行通信配线
成本 – –
每个模块中都有微控制器、CAN 接口和隔离，加上一块主控制器电路板 –
单个微控制器和 CAN 收发器，但是有具数字隔离器的 精密 PC 板 + +
单个微控制器、CAN 收发器和隔离器，在一块精密 PC 板上 +
单个微控制器、CAN 收发器和隔离器，但是有单独的精密 PC 板
功率 – –
多个微控制器和 CAN 接口需要过大的功耗 –
高速数字隔离器具极大的电流消耗 + +
具低功率 SPI 接口的最小电路系统 +
最小电路系统，但 SPI 接口需要更多功率以在电路板之间通信
并联独立 CAN 模块 (图 1)
Parallel Independent CAN Modules (Figure 1)
每个由 12 个电池组成的模块都含有一个 PC 板，板上有1个 LTC6802、1个微控制器、1个 CAN 接口和1个电流隔离变压器。系统所需的大量电池监视数据使主 CAN 总线难以应付，因此 CAN 模块必须在 CAN 子网上。CAN 子网由一个主控制器协调，该主控制器也为主 CAN 总线提供网关。
Each 12-battery module contains a PC board with an LTC6802, a microcontroller, a CAN interface, and a galvanic isolation transformer. The large amount of battery-monitoring data required for the system would overwhelm the main CAN bus, so the CAN modules need to be on local CAN subnets. The CAN subnets are coordinated by a master controller that also provides the gateway to the main CAN bus.
图 1 并联独立 CAN 模块
具 CAN 网关的并联模块 (图 2)
Parallel Modules with CAN Gateway (Figure 2)
每个由 12 节电池组成的模块都含有一个 PC 板，板上有一个 LTC6802 和一个数字隔离器。这些模块具有至控制器电路板的独立接口连接，该控制器电路板上含有1个微控制器、1个 CAN 接口和1个电流隔离变压器。微控制器协调这些模块，并为主 CAN 总线提供网关。
Each 12-battery module contains a PC board with an LTC6802 and a digital isolator. The modules have independent interface connections to a controller board containing a microcontroller, a CAN interface, and a galvanic isolation transformer. The microcontroller coordinates the modules and provides the gateway to the main CAN bus.
图 2：具 CAN 网关的并联模块的方框图
Digital Isolator：数字隔离器
具 CAN 网关的单个监视模块 (图 3)
Single Monitoring Module with CAN Gateway (Figure 3)
在这种配置中，由 12 节电池组成的模块中没有监视和控制电路。取而代之的是，单个 PC 板含有 8 个 LTC6802 监视器 IC，每个监视器 IC 都连接至其电池模块。LTC6802 器件通过非隔离式 SPI 兼容的串行接口通信。单个微控制器通过 SPI 兼容的串行接口控制整组电池监视器，该微控制器也是至主 CAN 总线的网关。CAN 收发器和电流隔离变压器是该电池监视系统的最后两个组件。
In this configuration, there is no monitoring and control circuitry within the 12-battery modules. Instead, a single PC board has eight LTC6802 monitor ICs, each of which is connected to its battery module. The LTC6802 devices communicate through non-isolated SPI-compatible serial interfaces. A single microcontroller controls the entire stack of battery monitors via the SPI-compatible serial interface, and it also is the gateway to the main CAN bus. A CAN transceiver and a galvanic isolation transformer complete the battery-monitoring system.
图 3：具 CAN 网关的单个监视模块的方框图
Monitoring Module：监视模块
具 CAN 网关的串联模块 (图 4)
Series Modules with CAN Gateway (Figure 4)
这种架构类似于单个监视模块，除了每个 LTC6802 都在由 12 个电池组成的模块内部的 PC 板上。8 个模块通过 LTC6802 非隔离式 SPI 兼容串行接口通信，这在电池模块之间需要连接 3 或 4 条传导电缆。单个微控制器通过底端监视器 IC 控制整组电池监视器，并作为至主 CAN 总线的网关。CAN 收发器和电流隔离变压器仍然是电池监视系统的最后两个组件。
This architecture is similar to the single monitoring module, except each LTC6802 is on a PC board within its 12-battery module. The eight modules communicate through the LTC6802 non-isolated SPI-compatible serial interface, which requires a three- or four-conductor cable to be connected between pairs of battery modules.
A single microcontroller controls the entire stack of battery monitors via the bottom monitor IC, and also acts as the gateway to the main CAN bus. Once again, a CAN transceiver and a galvanic isolation transformer complete the battery-monitoring system.
图 4：具 CAN 网关的串联模块的方框图
电池监视架构选择
Battery-Monitoring Architecture Selection
第一种和第二种架构一般而言比较具有挑战性，因为并行接口需要大量连接和外部隔离。为了应对这种复杂性的提高，设计师采用了独立地与每个监视器器件通信的方法。第三种 (具 CAN 网关的单个监视模块) 和第四种 (具 CAN 网关的串联模块) 架构采用了简化的方法，所受限制最少。
The first and second architectures are generally challenging due to the significant number of connections and the external isolation required for the parallel interface. For this added complexity, the designer has independent communication to each monitor device. The third (single monitoring module with CAN gateway) and fourth (series modules with CAN gateway) architectures are simplified approaches with minimal limitations.
LTC6802 可以满足所有 4 种配置的需求，为系统设计师留出了选择余地。该器件的两个变体也已开发出来，一个用于串联配置，另一个用于并联配置。LTC6802-1 用于叠置式 SPI 接口配置。多个器件可以通过一个接口串联连接，该接口无需外部电平移位器或隔离器，就可沿着电池组来回发送数据。LTC6802-2 允许用单个器件满足并联架构的需求。两种变体有相同的电池监视性能规格和功能。
The LTC6802 can address all four configurations, leaving the choice to the system designer. Two variants of the device have been created, one for series configurations and one for parallel configurations. The LTC6802-1 is designed for use in a stacked SPI interface configuration. Multiple devices can be connected in series through an interface that sends data up and down the battery stack without external level shifters or isolators. The LTC6802-2 allows individual device addressing in parallel architectures. Both variants have the same battery-monitoring specifications and capabilities.
电动汽车和大功率工业设备向电池组提出了大量要求。制造商期望用经济实惠的电池系统满足严格的可靠性要求。最新的电池监视 IC 使系统设计师能在无性能折衷的前提下，灵活地选择最佳电池组架构。
Electric vehicles and high-power industrial equipment place huge demands on battery packs. Manufacturers expect cost-effective battery systems that meet their stringent reliability requirements. The latest battery-monitoring ICs give system designers the flexibility to choose the best battery pack architecture without compromising performance.
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