Versions Compared

Old Version 3

changes.mady.by.user Nathan Lemma

Saved on

compared with

New Version 4

changes.mady.by.user Nathan Lemma

Saved on

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

Status

Status
colourBlue
titleIn progress

Owner

Nathan Lemma

Contributors

Nathan Lemma

Approver

Lakshay Gupta

Due date

On this page

Table of Contents
maxLevel2
minLevel2

❓ Problem statement

BPS is tasked with securing the safety and monitoring of the battery, such as current monitoring. Over-current of the battery can damage internal components and pose a risk to the driver.

💡 Research insights

There are 2 ways to measure current, either using a shunt resistor connected to the load or using a hall-effect sensor. They have their own pros and cons but they solve the same problem.

📊 Solution hypothesis

  • The solution is successful if we are able to track current reliably and transmit that data to the leaderboard.

🌈 Design 🪛  Design options

There are only 2 ways to measure current. Either measure the voltage across a resistor in series with the load or we can measure the magnetic field of the wire.

Option 1 - Voltage Across a Resistor

Option 2 - Magnetic Field of Wire

Overview

Current Sense Amplifier or Isolated Modulators/ADC

Hall-Effect Current Sensing

Screenshot

image-20240907-165605.pngimage-20240907-183949.png

Docs

View file
nameTI Current Sensing Doc.pdf

View file
nameTI Hall-Effect Current Sense.pdf

Pros and cons

(plus) Preferred

(plus) Temperature Stable

(minus) Affected by electric noise (can be isolated)

(minus) Power loss

(plus) Power Effective

(plus) Safer

(minus) Affected by magnetic noise

(minus) Less accurate

(lightbulb) Specs

Criteria:

  • Precision: 16bits

    • Range: 0-7A at 120V

    Pros and cons

    Tip

    Accuracy

    Tip

    Simplicity and cost

    Warning

    Affected by electric noise

    Warning

    Power loss and voltage drop

    Tip

    Electric isolation and no power loss

    Tip

    Measures both AC and DC current

    Warning

    Affected by magnetic noise and temperature

    Warning

    Zero-drift problems

    DECISION 1

    • Option 1 - Making the PCB though a shunt resistor

    In the future, members can look into the second option for a hall-effect version

    (lightbulb) Ideas

    image-20240907-204601.pngImage Added

    Figure 1 is a common method to measure current using a shunt-resistor. There are # steps to read the current:

    1. The differential voltage is fed into the Current Sense Amplifier and converted to a single-ended signal.

    2. This single-ended signal is connected to an ADC, digitizing the signal.

    3. The signal is sent to a microcontroller for processing.

    Current Sense Amplifier

    Isolated Modulator

    Design

    Accuracy

    Bigger shunt resistor allows for more accuracy

    Power Dissipation

    Smaller shunt resistor consumes less power

    ✅ Follow up

    #

    Decision

    Status

    Next steps

    1Use Option

    1 for the base design of the boardDecision 1

    Status
    colourYellowGreen
    titleIn ProgressCompleted

    •  Create the components for shunt resistor design.

    💎 Source files

    Type /link to add links to design files.
    • the prospective design

    2

    🔤 Vocab

    Current Sense Amplifier: Amplifies the small voltage drop across a shunt resistor to measure current accurately in circuits.

    Isolated Modulator: Converts analog signals to digital while maintaining electrical isolation, often used in high-voltage or noisy environments.

    Hall-Effect Sensor: Detects magnetic fields to measure position, speed, or current without direct electrical contact.

    Zero-drift: the phenomenon where a sensor's output signal shifts away from its baseline (or zero) value when there is no actual current flowing through the sensor; affects Hall-Effect Sensor

    💎 Resource files

    View file
    nameTI Current Sensing Doc.pdf

    How to Sense Current

    View file
    nameTI Hall-Effect Current Sense.pdf

    Hall-Effect White Paper

    View file
    nameComparing Shunt- and Hall-Based Isolated CurrentSensing Solutions in HEV-EV.pdf

    Shunt vs Hall-Effect

    View file
    nameComparing Isolated Amplifiers and Isolated Modulators.pdf

    Isolated Amplifiers vs Isolated Modulators