电动汽车和混合动力汽车中的霍尔效应电流传感

作者Georges El Bacha，系统工程师
Ali Sirohiwala，系统工程师
亚博棋牌游戏Allegro微系统有限责任公司

汽车市场正在从机械驱动和定时方法向电驱动系统过渡。霍尔效应器件被证明是唯一适合这些应用。本申请说明对实施因素进行了审查。亚博尊贵会员

介绍

Improved energy efficiency in HEVs and EVs can be attained by using electrically-driven actuators instead of belt-driven and hydraulic actuators. For instance, in traditional internal combustion engines a fan belt drives the cooling fan, which operates continuously while the engine is running. The same applies to power-steering pumps and other belt-driven loads.

Technology Replacement Benefits

Replacing belt-driven actuators with electric motors, as shown in figure 1, improves energy efficiency and allows for greater control of the actuators. Precision, high-speed current-sensor ICs provide the bandwidth, response time, low noise, and accuracy performance necessary to optimize motor performance. They also allow quick detection of malfunctions by reporting overcurrent conditions and triggering protection circuits.

Figure 1. Power-efficient electric actuators

Allegro Hall effect current sensors ICs are factory trimmed to provide uniform sensitivity and minimize offset voltage through the entire operating temperature range. The small footprint of these packages, along with designed-in galvanic isolation, facilitates high-side and low-side current sensing while saving PCB area, and particularly when compared with the traditional sensing solutions based on sense resistance and operational amplifier current, such as that shown in figure 2.

图2。典型霍尔电流传感器集成电路的PCB体积比较
传统感测电阻和运算放大器电流感测

所示SOIC封装是典型的霍尔解决方案。在快板中ACS714, one of the product lines that use this package, a low-resistance integrated conductor serves as the path for the sensed current (figure 3, left panel), bringing it into close proximity to the sensing elements while maintaining galvanic isolation. This minimizes power loss and facilitates the high accuracy measurements required by advanced HEV systems.

Figure 3. Smart battery current sensing. The Illustration on the left shows
the integrated primary sensed current path featured in the ACS714.

Case in Point: Smart Batteries

An increasingly relevant example of low-side current sensing implementation is charge current monitoring for smart battery systems. As shown in figure 3, in addition to the two battery terminals, these battery systems typically have two diagnostic signals: a single-wire data line for battery health, and a single-wire thermistor output for battery temperature monitoring. These diagnostics are referenced to the negative terminal of the battery.

看似简单的传感电阻解的设计复杂度直接影响传感决策的效率和准确性。在这种应用中使用感测电阻器时，设计工程师必须考虑各种关键误差项。其中最主要的是，电阻器将从电池中消耗大量的能量作为热量，使系统效率低下，在应用中需要额外的热传递结构。

Second, the thermal phenomena also affect the sense voltage, V_SENSE在图3中，这将通过感测电阻器展开。此外，感测电阻运算放大器解决方案要求_SENSEbe superpositioned on the thermistor voltage, V_THERM. 这会使充电控制器看到的电压升高，从而：

V′_SENSE= V_SENSE+ V_THERM,

resulting in an enhanced error factor in the monitored battery temperature. This hampers the charging control of the battery system and thereby eventually undermines battery life, which is a crucial component to the success of HEV and EV systems.

要对比霍尔效应传感器IC解决方案，首先要考虑最基本的因素，导体电阻。集成导体的电流路径电阻简单而低得多，低至100μΩ。这大大降低了整个应用程序的功耗。

另一个重要的考虑因素是，集成导体回路的端子上几乎形成零电压。将电压降至最低可提高热敏电阻诊断信号（V）的准确性和完整性_SENSEis driven to its lower limit).

霍尔效应技术的一个根本优势在于电流和感应信号响应之间的磁耦合。这是因为在实际温度范围内，所感测的基于电流的磁特性不依赖于热。这不仅确保了响应与电流电平变化的整体线性，而且先进的霍尔效应器件可以结合逻辑电路，使其高度可定制，并提供可编程的温度偏移，进一步提高性能。

这简化了整个系统的设计挑战，并将霍尔集成电路与相对粗暴的力感电阻运算放大器方法形成鲜明对比，其复杂的元件依赖于导体电阻与精度。当使用感应电阻op-amp方法时，必须使用低电阻值以最小化功耗。然而，低电阻也有相反的效果，降低了精度性能，因为将感测到非常小的电压。如前所述，先进的霍尔集成电路可以在极低的电压下工作。此外，设备后端级可以输出经过调节的数据信号，以符合应用系统的要求，而不影响集成解决方案的优越精度和低功耗。

Practical Sensing Solutions

亚博棋牌游戏Allegro微系统有限责任公司has developed a line of fully integrated Hall-effect current sensor ICs that provide highly accurate, low noise output voltage signals proportional to an applied AC or DC current, bidirectional or unidirectional. The basic categories of devices are displayed in figure 4.

Figure 4. Allegro Hall-effect current sensor IC typical package categories

Allegro proprietary integrated Hall-effect devices employ advanced IC and packaging techniques for sensing current from 5 to 200 A. Even larger currents can be measured using a Hall IC and an external magnetic concentrator or core. Allegro current sensor ICs allow design engineers to use Hall-effect based current sensor ICs in new EV and HEV applications where increased energy efficiency or new operating features are required. Wherever current sensing is needed, an integrated Hall-effect IC can provide a solution.

本文件中包含的信息不构成Allegro就本文件主题向客户作出的任何陈述、保证、保证、担保或诱因。所提供的信息不能保证基于此信息的过程是可靠的，或者Allegro已经探索了所有可能的故障模式。客户有责任对最终产品进行充分的鉴定测试，以确保其可靠并满足所有设计要求。