JAJU837 March   2022

 

  1.   概要
  2.   Resources
  3.   特長
  4.   アプリケーション
  5.   5
  6. 1System Description
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Highlighted Products
      1. 2.2.1 TMAG5170
      2. 2.2.2 DRV5055A4
    3. 2.3 Design Considerations
      1. 2.3.1 Magnet Selection
      2. 2.3.2 Magnet Shape
      3. 2.3.3 Magnet Rotation Speed
      4. 2.3.4 Sensor Location
      5. 2.3.5 Expected Performance
      6. 2.3.6 Layout for Sensor Location
      7. 2.3.7 45° Alignment
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Setup
      1. 3.2.1 Test Equipment
      2. 3.2.2 Test Hardware Configuration
      3. 3.2.3 Test Software Configuration and Initial Data Capture
    3. 3.3 Test Results
      1. 3.3.1 Calibration Methods
      2. 3.3.2 TMAG5170 On-Axis
      3. 3.3.3 TMAG5170 In-Plane
      4. 3.3.4 TMAG5170 Off-Axis
      5. 3.3.5 TMAG5170 45° Alignment
      6. 3.3.6 DRV5055 Off Axis Result
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Tools and Software
    3. 4.3 Documentation Support
    4. 4.4 サポート・リソース
    5. 4.5 Trademarks

TMAG5170 In-Plane

The in-plane alignment differs from the on-axis approach in that the sensor is placed coplanar to the magnet. This produces the smallest profile solution overall, but produces highly imbalanced input magnitudes.

Additionally, this alignment is the most susceptible to mechanical errors which is evident when examining the peak angle error. This position is very sensitive to eccentricity errors in the magnet rotation. Any magnet centering misalignment results with a changing airgap range. As demonstrated in In-Plane Magnitude vs Airgap Distance, small variations at this range have a significant impact on the magnitude of the magnetic field. It is particularly important when configuring a sensor in this position to exercise a great deal of care to achieve an exact mount for the magnet.

Additionally, at the outer edge of the magnet, the field vector direction is constantly changing as it wraps around to the opposing magnet pole. As a result tilt and alignment errors will result in phase error and changing input amplitudes.

GUID-20220208-SS0I-NR3F-DRLZ-DLGVZZZTK8ZZ-low.pngFigure 3-13 In-Plane Configuration

In-Plane Mechanical Angle Error shows the resulting pre-calibrated error captured for this alignment.

Figure 3-14 In-Plane Mechanical Angle Error

The angle error shown for the in-plane alignment appears quite extreme. With the assembly alignment errors for this test setup, a very dramatic angle error resulted. Even with this extreme of an error, it is still possible to apply a calibration to the end result to achieve accuracy below 0.1°.

Table 3-3 In-Plane Harmonic Correction Factors
HARMONICαiβi
15.332.68
2–0.5–1.22
3–0.260.51
40.170.05
5–0.04–0.02

In-Plane Calibrated Angle Error shows the resulting error for both a direct arctangent calculation and for the CORDIC output after applying the harmonic data.

Figure 3-15 In-Plane Calibrated Angle Error