用于燃油电平传感的霍尔传感器
用于燃油电平传感的霍尔传感器
使用Hall效应传感器IC的燃油电平传感器- Allegro MicroSystems
By Shashank Wekhande and Ranjit Farakate,
Avantgarde Solutions PVT。有限公司，
Consultant to Allegro MicroSystems, LLC
Abstract
Hall-based fuel level sensor ICs are developed to provide high reliability and accurate fuel level sensing for automotive applications. The application of linear and angle sensor ICs for coil-based and digital cluster indicators is presented in this applications note.
Introduction
所有汽车中使用燃油电平传感器（FL）以指示燃料水平。各种方法用于测量燃料水平，例如电阻膜，离散电阻，电容和超声波。基于电阻的传感器最常用于此应用。这些传感器机械地连接到浮子，该浮点数根据燃料水平向上或向下移动。随着浮动移动，传感器的电阻变化。该传感器是燃料表显示电路的电流平衡电路的一部分，其通常由用于致动显示针的线圈组成。随着燃料传感器的电阻改变，针的位置与在线圈中流动的电流成比例。图1中示出了一种基于电阻的杂物。
The disadvantage of the resistive contact-based sensor is the wear and tear of the sensor due to the sliding contact inside the sensor elements. The wear and tear leads to a reduction in the sensor life.
本文介绍了使用基于霍尔的传感器IC的方法进行FLS应用的非接触式感测。雷竞技最新网址
Non-Contact Hall-Sensor-Based FLS
霍尔传感器IC通常感测通过IC的磁场。对于燃料感测应用，必须安装直径磁体，使得其旋转运动与浮动运动成比例。此外，传感器还需要安装在磁铁附近。与其他非接触式传感器技术相比，这更简单地采用改装。可以密封磁铁以保护其免于燃料内的降解。即使燃料被污染，传感操作也不会受到影响。
Hall Sensor IC Options for FLS
Allegro为FLS应用提供了各种选项，以满足精度，线性，输出接口和成本。雷竞技最新网址
- Linear Hall-Effect Sensor
Linear Hall-effect sensor ICs have an output signal that is proportional to absolute magnetic field. The IC output voltage changes based on magnetic field.
- PWM.Output:PWM输出提供了更好的抗噪声等优点。这些类型的传感器适用于基于跨线圈的簇。
- 模拟电压:In digital clusters, often a microcontroller is used to interface with the LCD and sensor output. An analog input voltage from the sensor is given to the ADC input of the microcontroller. These ICs operate from either a 3.3 V or a 5 V supply and ratiometric to the supply.
Two-point programming offers compensation for magnet and air gap variation. Allegro also offers multipoint programming to adapt to non-uniform tank geometry.
- 角度厅传感器
Angle sensors are based on measurement of the absolute angle of the magnetic field. This eliminates error due to magnet and air gap variation.
- PWM.Output:PWM.output ICs offer advantages such as better noise immunity and direct connection to the vehicle battery.
- 模拟电压:集成电路提供es analog output voltage proportional to angle.
- PWM.Output:PWM.output ICs offer advantages such as better noise immunity and direct connection to the vehicle battery.
Table 1: Sensor Offerings by Allegro MicroSystems for Fuel Sensing Purpose
| Sensor | Output | Technology | Programmability | Accuracy | Cost |
| A1356 | PWM. | Linear Hall | 灵敏度+ QVO偏移 | Better | 低 |
| A1377 | 模拟电压 | Linear Hall | 灵敏度+ QVO偏移 | Better | Medium |
| A1330 | Analog + PWM | 角厅（CVH） | Gain + Short Stroke + Zero Offset + Clamp + Averaging + Rotation | Best | 低 |
| A1338 | PWM. | 角厅（CVH） | Zero Offset + Averaging + Rotation | Best | High |
油箱建筑
Fuel tank construction varies from automotive model to model. Some tanks with regular geometry result in a linear volume to float angle. For such tanks, only two-point programming would suffice. An example of a uniform fuel tank and its characteristics are shown in Figure 2.
However, a majority of the fuel tanks are non-uniform in terms of volume to float angle. A typical non-uniform tank and its characteristics are shown in Figure 3. For these type of tanks, multipoint
programming in the IC is required for output signal linearization.
用于基于线圈的簇的模拟液体线性PWM霍尔传感器
This is the most commonly used FSU for low-cost applications. The cross-coil arrangement is shown in Figure 4. One side of the coil is directly connected across the battery and the other side is connected to battery with a series sensor connection. The coil resets to its normal position when currents in both coils are the same. The needle deflects from normal position when sensor current varies. This arrangement offers cancellation for battery voltage variation. Sensor current to needle angle is not linear due to thermal effects.
TheA1356 IC.提供系统级比率（输出，根据电源电压调整）输出解决方案，具有最小的组件。A1356采用内部反向电池保护。该IC提供两点磁场编程，可调节偏移和灵敏度。这允许4至18V补偿磁体，线圈和制造空气隙公差。
基于A1356的FSU的应用电路如图5所示。
The RC filter of R2 and C2 converts PWM output of the A1356 to a proportional analog voltage. MOSFET Q1 converts this voltage to a current output suitable to drive the coil.
Magnet selection is not very critical for this application. NdFeB or ferrite magnets are suitable for this application. For better repeatability, magnets with tighter tolerances should be used.
用于本申请的磁体是图7中所示的直径类型的磁体（圆形），其装配在浮子的枢轴上，传感器放置在磁体表面上，磁体表面具有2毫米的气隙，如图6所示。磁铁取向和线性霍尔传感器定位如图8所示。
EXPERIMENTAL RESULTS
Figure 9 shows linear coil current with respect to float angle. Coil current changes with supply voltage and is inherently non-linear due to self-heating thermal effects.
Linear Analog Hall-Effect Sensor for Digital FLS with Microcontroller-Based Cluster
TheA1377是一个可编程线性采用霍尔传感器哪个provides an analog output voltage proportional to magnetic field. The A1377 provides a ratiometric output between 4.5 and 5.5 V input supply voltage. Use the 5 V supply from the cluster used by the interfacing ADC to power the A1377. A linear analog Halleffect sensor-based digital FLS is shown in Figure 10.
The A1377 provides two-point magnetic field programming to adjust offset and sensitivity. This allows users to compensate for magnet, coil, and manufacturing air gap tolerances.
EXPERIMENTAL RESULTS
图11示出了相对于浮动角度的线性输出电压。输出电压是线性的超过50度的浮法角位移。
Figure 12 shows the A1377 linear sensor and magnet placement on the fuel sensor assembly.
角度厅传感器for Digital FLS with Microcontroller-Based Cluster
Linear sensors suffer from errors due to air gap or magnet drifts. Linear angle sensors are also suitable up to 60 degrees angular displacement. Angle sensors provide wide angular displacement measurement with output voltage independent of air gap and absolute magnetic field. The A1330 is a 360° angle sensor IC that provides contactless angular position based on magnetic circular vertical Hall (CVH) technology. An angle Hall sensor-based digital FLS is shown in Figure 13. This application uses a diametric magnet.
Programmable parameters include zero offset to provide flexible magnet placement and short angular displacement for full dynamic range.
EXPERIMENTAL RESULTS
A1330具有浮动角度的输出电压如图14所示，具有6mm×3mm直径磁体。结果显示线性输出电压超过75度的位移，其与气隙无关。
Figure 15 shows the A1330 angle sensor IC and magnet placement on the fuel sensor assembly.
For battery operated FLS, use the non-ratiometric version of A1330 and provide local LDO in fuel sensor assembly.
A PWM output version of A1330 can be used for digital FLS for better noise immunity.
Table 2: Comparison of Various Programmable Hall Sensor Options
| Sensor | 应用 | Pros | Cons |
| A1356 Linear Sensor (PWM) |
线圈为基础 Analog FLS |
更好的抗噪性，电池电压的比例输出，偏移 和灵敏度编程补偿磁铁和气隙 制造过程中的公差。 |
磁铁方向至关重要 during assembly. Output error with 磁场漂移。 |
| A1377 Linear Sensor （模拟） |
Digital FLS | 偏移和灵敏度编程补偿磁铁和气隙 制造过程中的公差。 |
磁铁方向至关重要 在装配时，输出错误 磁场漂移。需要5 V. supply. |
| A1330 Angle Sensor (Analog + Ratiometric) |
Digital FLS | 输出电压与气隙和绝对磁场无关， flexible magnet placement, short angular displacement for full 动态范围，SMD包装。 |
需要5 V群集。 |
| A1330 Angle Sensor （模拟+非 Ratiometric) |
Analog FLS | 输出电压与气隙和绝对磁场无关， Flexible magnet placement, short angular displacement for full 动态范围，SMD包装。 |
Needs LDO for 5 V supply. |
| A1330 Angle Sensor (PWM) |
Digital FLS | 输出电压与气隙和绝对磁场无关。 Flexible magnet placement, short angular displacement for full dynamic range, better noise immunity, SMD package. |
需要5 V.supply from cluster or 我愿意。 |
Conclusion
Hall-based fuel level sensing offers reliable non-contact fuel measurement for automotive applications. Allegro offers a wide range of Hall sensors suitable for different FLS systems. All the sensors use simple diametric magnet and offers programming to achieve a linear output signal, even with asymmetric fuel tank shapes.
Copyright ©2017, Allegro MicroSystems, LLC
本文档中包含的信息不构成Allegro的任何代表性，保修，保证，担保或诱导
客户关于本文件的主题。提供的信息不保证基于此信息的过程
will be reliable, or that Allegro has explored all of the possible failure modes. It is the customer’s responsibility to do sufficient qualification
testing of the final product to insure that it is reliable and meets all design requirements.