先进的霍尔效应线性电流传感器IC使混合动力电动汽车和其他高电流传感应用中的高BW传感成为可能雷竞技最新网址
先进的霍尔效应线性电流传感器IC使混合动力电动汽车和其他高电流传感应用中的高BW传感成为可能雷竞技最新网址
由肖恩·米兰所作，
雷竞技竞猜下载Allegro微系统有限责任公司
摘要
为适应混合动力电动汽车（HEV）逆变器电流传感应用的精度和带宽要求，开发了一种新型线性电流霍尔效应传感器芯片。该设备使用专有的SIP封装，并采用新一代斩波稳定信号调理和滤波电路，结合起来提供低噪声，高达120千赫带宽的模拟输出信号。通过引入专有的分段线性温度补偿，可在整个工作温度范围内稳定零场偏移和输出灵敏度，而不影响高带宽信号路径，从而实现行业领雷竞技最新网址先的精度水平。该设备是理想的所有电流传感应用使用的核心配置，需要高频操作。本文以混合动力汽车逆变器的应用为例。
介绍
A full bridge driver in a typical HEV inverter converts DC battery voltage to 3-phase AC voltage to drive an AC motor connected to the drive train (see Figure 1).
图1：典型逆变器电路应用
测量逆变器相电流，所得信息用于控制脉宽调制（PWM）逆变器开关（通常为IGBT）。逆变器控制回路需要高带宽、高精度的电流传感器集成电路，以最大限度地提高电机转矩和电机整体效率。具有快速响应时间的高侧电流传感器IC也可实现过流保护。这个快板™ A1366线性霍尔效应传感器IC已被设计为满足高带宽，高精度要求的混合动力汽车逆变器的应用。在这些应用中，线性霍尔效应传感器IC通常放置在铁磁“C”磁芯的间隙中，该磁芯包围电机中的每个逆变器相导体（见图2）。当雷竞技最新网址电流在导体中流动时，磁芯通过单列直插封装（SIP）集中产生的磁场。
图2: A1366 Current Sensing Configuration
Allegro’s proprietary design features make the A1366 an ideal sensor IC for use in HEV inverters, high current motor control, or any other high frequency, high current applications. These features include special packaging, advanced chopper and filtering techniques, and a digital temperature compensation algorithm. These innovations make possible an industry leading, high accuracy, 120 kHz bandwidth linear Hall-effect sensor IC that performs well in HEV current sensor applications.
本文将重点讨论下一代封装，以及集成电路设计创新及其对传感器集成电路性能的影响。它还将包括核心设计的简短应用讨论。
Functional Description
模拟信号路径和带宽
图3shows a simplified block diagram of the A1366 linear Hall-effect sensor IC. The analog signal path of the sensor can be clearly seen. The analog output signal is ratiometric to the supply voltage, and it is nominally VCC/2 when the applied magnetic field is zero. The output will deviate from VCC/2 either in a positive or negative direction, depending on the polarity of the applied magnetic field or direction of current in the core configuration of Figure 2.
图3: A1366 Block Diagram
The Hall element transducer generates a small signal that must be amplified with high gain. High amplification makes it difficult to create a stable output signal as the ambient temperature changes. The amplifier designs of the A1366 are made possible with a BiCMOS process that allows accurate amplifier design in conjunction with digital circuitry. The increased digital circuitry is used for factory programming at Allegro. Both the gain and offset can be adjusted over the operating temperature range. Furthermore, both the Hall element and the amplifier stages are chopper-stabilized to minimize the offset drift over temperature. Allegro has also developed proprietary chopper stabilization and notch filtering techniques that result in a low noise output, despite the large signal gain required in a linear Hall-effect sensor IC. In fact, the generational improvements in noise reduction are greater than an order of magnitude. The A1366 represents the highest bandwidth and highest resolution analog output sensors ever produced at Allegro. The six sigma peak-to-peak noise is approximately 6 mV at the full 120 kHz bandwidth.
The analog output response time of the A1366 is less than 4 μs, which is fast enough to protect IGBT devices from over-current or short circuit events. In lower frequency applications, the output can be filtered to lower the noise on the output and improve the resolution. The high bandwidth is made possible not only through the analog signal path design, but also the Single In-line Package (SIP), called the KT package.
包装
由于霍尔传感器后面有大量的铜线框，普通的SIP封装限制了带宽。这种金属垫允许在更快的dɸ/dt事件中形成涡流。涡流在引线框架上产生相反的磁场。这些场减慢了系统的响应，并反映在线性霍尔效应传感器IC的输出上。Allegro KT封装去除霍尔元件正后方的引线框架材料，以消除霍尔元件区域的涡流。如果不修改KT包，就不可能进行更高带宽的操作。Allegro专有软件包非常有效，与标准软件包中使用的相同IC相比，KT软件包中A1366的工作带宽提高了3到4倍。
同样的包装改进也可在8针TSSOP封装中使用，用于客户有需要表面贴装焊接的机械设计的应用中。雷竞技最新网址
数字温度补偿
为了提高用于电流传感器应用的线性霍尔效应传感器集成电路的整体精度，许多供应商采用了全数字信号通路。数字滤波和信号调理的缺点是信号带宽的损失，因为数字信号处理和信号调理将传感器带宽降低到1到3 kHz的范围雷竞技最新网址，使得它们对于HEV逆变器应用来说太慢。Allegro用一种新的数字补偿方案解决了这个问题。
A1366的精度大大提高了一个专有的数字温度补偿算法，包括EEPROM技术的增加。在五个边界之间采用分段线性温度补偿，在不牺牲信号带宽的前提下，大大减小了模拟信号路径的本机漂移。图4说明了该技术。该算法可以调节静态场电压输出（QVO）和灵敏度。QVO或灵敏度的本机漂移用虚线表示。虚线显示边界之间添加的线性补偿，实线显示传感器输出的结果行为。
图4: Temperature Compensation Algorithm Results
A1366有一个板载温度传感器，用于确定相邻边界。数字控制引擎应用适当的补偿。
由于温度变化与被测电流相比非常缓慢，补偿方案在后台工作，必要时不断调整QVO和灵敏度。这样，保持了120khz的传感器模拟信号通路，优化了器件精度。
Allegro制造集团通过温度范围对设备进行测试，并将QVO和灵敏度温度补偿系数编程到EEPROM中，消除了客户对最终传感器组件进行温度测试的要求。
A1366 QVO和灵敏度绝对值也在Allegro工厂编程。灵敏度的标准产品包括1、2.5、5和10 mV/G。设备零场输出电压QVO编程为2.500 V。Allegro还有一个客户可编程设备A1363，可供需要在其最终应用中编程设备的客户使用。A1363提供了对灵敏度和QVO绝对值的编程控制，客户可以在25℃下线测试时将其编程到EEPROM中。
核心设计
As mentioned earlier, the A1366 linear Hall-effect sensor IC is designed to be used with a ferromagnetic core in a through-hole configuration (as shown in Figure 2) in HEV applications. Core material choice depends on the tradeoffs between:
- residual magnetism after signal excursion;
- 频率响应；
- the linearity of applied magnetic field versus applied current.
最常见的选择是层压钢芯。这是非常具有成本效益，并尽量减少涡流，从而允许优秀的频率响应。叠层磁芯的磁滞在大多数应用中通常是可以接受的。雷竞技最新网址
铁磁芯的横截面积取决于一次导体中感应到的最大电流量。这也很大程度上取决于材料的选择。必须注意确保材料不会在高温下饱和并产生非线性响应。Allegro应用程序支持适用于需要核心设计和材料选择帮助的客户。雷竞技最新网址
A1366精度
The A1366 high programmability of QVO and Sensitivity, as well as the piecewise linear temperature compensation improvements, result in a 3X to 4X improvement over existing linear Hall-effect sensor ICs.
灵敏度和QVO
The result of the techniques described throughout this paper combine in the A1366 to produce a high bandwidth, linear Halleffect sensor IC with nearly closed-loop accuracy performance in an open-loop sensor. Please see Figures 5 and 6 for graphs showing the performance of QVO and Sensitivity versus temperature. The graphs show a typical ±3 sigma sensitivity drift over temperature of less than ±1%, and a ±3 sigma QVO distribution of ±6 mV through the operating temperature range of –40ºC to 150ºC.
图5:QVO与温度的关系
图6：灵敏度与温度
结论
Allegro A1366线性霍尔效应传感器IC设计用于高精度和高带宽应用，如HEV逆变器中的应用。在封装，斩波稳定放大器，先进的滤波和创新的数字温度补偿电路的改进结合起来，提供了一个几乎闭环性能的传感器芯片在一个开环雷竞技最新网址电流传感器系统。即使是在低带宽线性霍尔传感器集成电路中也无法实现的低误差水平，现在可以在较宽的汽车工作温度范围内和高达120千赫的带宽下实现。
文章发表于Hanser Automotive，2015年2月。经允许转载。