BPS Amperes PCB
Status | In progress |
Owner | @Nathan Lemma |
---|---|
Contributors | @Nathan Lemma |
Approver | @Lakshay Gupta |
Due date | Nov 30, 2024 |
On this page |
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 | ||
Pros and cons | Accuracy Simplicity and cost Affected by electric noise |
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
Ideas
Figure 1 is a common method to measure current using a shunt-resistor. There are 3 steps to read the current:
The differential voltage is fed into the Current Sense Amplifier and converted to a single-ended signal.
This single-ended signal is connected to an ADC, digitizing the signal.
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.
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 |
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|
Accuracy | Bigger shunt resistor allows for more accuracy | |
Power Dissipation | Smaller shunt resistor consumes less power |
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Follow up
# | Decision | Status | Next steps |
---|---|---|---|
1 | Completed | Create the components for the prospective design | |
2 |
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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
How to Sense Current | Hall-Effect White Paper | Shunt vs Hall-Effect | Isolated Amplifiers vs Isolated Modulators |
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