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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 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

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 RemovedAmperes Board Diagrams-Figure 1.drawio.svgImage Added

Figure 1 is a common method to measure current using a shunt-resistor. There are # 3 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.

High Side vs Low Side

For reading the current, there are 2 different configurations you can have your device hooked up to.

Amperes Board Diagrams-Figure 2.drawio.svgImage Added

Figure 2 shows an example of the current sense amplifier connected to the shunt resistor in a high-side sending configuration.

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

1

Decision 1

Status
colourGreen
titleCompleted

  •  Create the components for 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