Embedded Systems and Design & Development - Feb 12, 2026 | Afternoon | VisionAstraa EV Academy

Introduction to Offline Classes

Overview of the Session

• The speaker welcomes participants and expresses excitement about showcasing offline class activities.

• Participants will engage in hands-on work with complete vehicles, including disassembly and understanding vehicle integration.

Hands-On Learning Experience

• Students will dismantle various components such as batteries, motors, and controllers to learn about their integration.

• Different types of motors (e.g., mid-drive motor) will be explored through practical application on multiple vehicle brands.

Offline vs. Online Class Structure

Distinct Learning Approaches

• Offline classes provide a hands-on experience with physical vehicles, while online classes focus on design concepts from home.

• Both formats offer unique learning opportunities; offline sessions emphasize practical exposure, whereas online sessions cover theoretical aspects.

Student Engagement

• The speaker encourages students to indicate their attendance for offline or online classes, highlighting a mix of both participation types.

Battery Pack Design Calculations

Previous Session Recap

• The last session concluded with calculations related to a 50 kW car battery pack based on a 300V architecture.

• Students are now capable of redesigning battery packs using data sheets for various capacities (20 kW, 100 kW).

Moving Forward with Battery Technology

• Transitioning to sensor discussions after completing calculations for NMC and LFP battery packs.

Charging Time Calculation

Importance of Charging Time

• A key topic left out was the calculation of charging time for the NMC battery pack.

Practical Application

• The session aims to quickly review how to calculate charging time before moving onto sensors used in electric vehicles.

Charging Time Calculations for Battery Packs

Overview of Charging Time Formula

• The charging time is calculated using the formula: Charging Time = Battery Capacity / Charging Current. This was discussed in relation to a battery pack with a capacity of 200 Ah and a selected charging current of 40 amps for the onboard charger.

Onboard Charger Specifications

• The onboard charger was designed with a charging current of 40 amps, which allows for straightforward calculations regarding charging times.

• For a 50 kW battery pack, the required charging time is calculated as follows: 200 Ah / 40 A = 5 hours. This indicates that it takes five hours to fully charge the battery using the onboard charger.

LFP Battery Pack Charging Characteristics

• Similar calculations were performed for an LFP (Lithium Iron Phosphate) battery pack, which also resulted in a charging time of 5 hours when charged at 40 amps with an onboard charger.

Offboard Charger Insights

• An offboard charger was mentioned, which has a higher charging current of 200 amps. Using this offboard charger, the total charging time can be calculated as: 200 Ah / 200 A = 1 hour, allowing for rapid recharging capabilities at offboard stations.

Introduction to Vehicle Sensors

Importance of Sensors in Vehicles

• The discussion transitioned to vehicle sensors, emphasizing their critical role in automotive systems; nearly 90% of vehicle parts are equipped with sensors necessary for feedback and operation monitoring. Without these sensors, microcontrollers cannot effectively gauge conditions within components like battery packs.

Types of Sensors Used in Vehicles

• Several key types of sensors were identified:

• Hall Sensor: Used for various applications within vehicles.

• Current Sensor: Essential for measuring electrical currents.

• Voltage Sensor: Important for monitoring voltage levels.

• Temperature Sensor: Critical for managing thermal conditions.

• Pressure Sensors: Utilized across different systems within vehicles.

Data Input to Microcontrollers

• The session highlighted how data from these sensors feeds into microcontrollers, enabling them to process inputs and control vehicle functions effectively based on real-time data from various sensor types such as CTN (Current Transformer) and PT (Potential Transformer). Understanding this input mechanism is crucial for developing efficient automotive systems.

Temperature Control System Using Microcontroller

Overview of the Temperature Sensor and Microcontroller Interaction

• The temperature sensor is designed to detect ambient temperature, sending this data to a microcontroller for processing.

• The sensor requires two power inputs (positive and negative) to operate effectively while transmitting temperature readings.

• For example, if the surrounding temperature is around 30°C or 40°C, the sensor will relay this information to the microcontroller.

Battery Pack Heating and Cooling Mechanism

• A battery pack, potentially rated at 300 volts, generates heat during operation due to energy consumption.

• To manage overheating, a cooling mechanism must be implemented; in this case, a fan will be used to dissipate heat from the battery pack.

Fan Activation Based on Temperature Readings

• The fan's operation will be controlled by the microcontroller based on real-time temperature data from the sensor.

• A program will dictate that if temperatures exceed 60°C, the fan should activate; otherwise, it remains off.

Circuit Design and Functionality

• The circuit includes a switching device (like a MOSFET), which allows the microcontroller to control when the fan turns on or off based on input from the temperature sensor.

• If temperatures are below 60°C, no action is taken; once they rise above this threshold, signals are sent to activate cooling measures.

Summary of System Operation

• This system illustrates how simple circuits can integrate sensors and actuators for effective thermal management in battery packs.

• The design emphasizes clear operational parameters: activating cooling systems only when necessary based on precise temperature thresholds.

Instrumentation Types Relevant to Monitoring Systems

• Different types of instrumentation exist for monitoring purposes; these include recording instruments that log data over time as well as displaying instruments that provide real-time feedback.

• Understanding these instrumentation types is crucial for interpreting data collected from various sensors within a system.

Data Collection and Processing by Microcontrollers

• Microcontrollers aggregate data from multiple sources (e.g., temperature sensors), allowing comprehensive analysis of system performance and conditions.

Understanding Brake Systems in Electric Vehicles

Introduction to Brake Light Functionality

• The brake light illuminates when the brake is engaged, indicating that the vehicle is slowing down. This functionality is crucial for safety and communication with other drivers.

Importance of Brake Sensors

• Brake sensors are essential components in electric vehicles (EVs), as they detect when the brake is applied and activate corresponding systems, such as tail lights.

Basic Circuit Design for Brake System

• A simple circuit can be designed using an LED connected to a battery. When the positive and negative terminals are connected, the LED lights up, demonstrating basic electrical principles.

• By incorporating a switch into this circuit, which acts as a brake sensor, pressing the brake completes the circuit and activates the tail light.

Analyzing Load Conditions on Motors

• In an EV setup with a 60V battery pack and motor control unit (MCU), understanding load conditions is vital. At no load, motors draw minimal current (e.g., 1.5 amps).

• When additional weight (like a person sitting on the vehicle) is added, current draw increases significantly (e.g., up to 10 amps under load).

Interaction Between Throttle and Braking

• Applying brakes while throttling creates conflicting demands on the motor: increasing speed versus stopping it. This situation leads to increased load on the motor.

• The simultaneous application of throttle and brakes results in higher current consumption from the battery pack due to increased mechanical load on the motor.

Current Limits in Battery Management Systems

• Battery management systems (BMS) set limits on current draw; for example, a 3C battery pack may allow up to 90 amps maximum output. Understanding these limits helps prevent damage during high-load scenarios.

Mechanical Braking and Power Management in EVs

Understanding Mechanical Braking

• The mechanical braking system aims to stop the motor by drawing maximum current from the battery pack, potentially increasing load up to three times.

• When a brake is gradually applied, current consumption increases significantly; however, user behavior can complicate this process as they may hold the brake while accelerating.

User Behavior and System Limitations

• In practical scenarios, users might hold the brake during maneuvers like U-turns, which can lead to increased load on the motor in electric vehicles (EVs).

• It’s challenging to instruct users not to hold the brake since their actions are unpredictable and beyond manufacturer control.

Brake-by-Wire System Implementation

• To mitigate issues caused by user behavior, a brake-by-wire system is implemented. This system uses sensors that communicate with a microcontroller (MCU).

• The MCU is programmed to prevent power from being sent to the motor when brakes are applied, protecting the motor from potential damage.

Microcontroller Functionality

• Upon detecting that brakes are pressed, the MCU stops sending power to the motor while still allowing power flow for other functions.

• There will be no changes in power paths between components; separate systems manage different functionalities without interference.

Integration of Multiple Microcontrollers

• A single MCU cannot handle all sensor data due to size constraints; thus, multiple microcontrollers are used for efficient data management.

• Each microcontroller integrates specific features related to sensors and actuators within the overall braking system.

Regenerative Braking: Power Recovery Mechanism

Concept of Regeneration During Braking

• Regenerative braking allows energy recovery when brakes are applied. The MCU manages both stopping power and energy regeneration simultaneously.

Dual Functionality of Motors

• The machine operates as both a motor and generator; it generates power when mechanical energy is supplied back into it during deceleration.

Practical Application of Regenerative Braking

• As an EV accelerates and then releases throttle while moving, it continues generating energy through regenerative braking mechanisms.

This structured approach provides clarity on key concepts discussed in relation to mechanical braking systems and regenerative capabilities within electric vehicles.

Understanding Regenerative Braking in Electric Vehicles

How the Motor Functions as Both Motor and Generator

• The motor operates simultaneously as a motor and generator. When throttled, power flows from the battery to the MCU (Motor Control Unit) and motor.

• Upon releasing the throttle, the rotating motor generates power, attempting to recharge the battery pack.

• This process is known as regenerative braking, where mechanical power generated by the motor can recharge the battery.

Role of MCU in Power Management

• The MCU manages two options for regeneration: direct regeneration without delay or controlled regeneration based on throttle response.

• When brakes are applied, even if throttle is engaged, the MCU cuts off power from the battery pack to prevent energy loss during braking.

• The brake sensor plays a crucial role in this system by ensuring that when brakes are applied, power is redirected back to recharge the battery.

Power Consumption Dynamics

• At no load conditions (e.g., center stand), power consumption is minimal; however, adding weight increases current consumption significantly.

• As mechanical load increases, both power consumption and force exerted by the motor increase proportionally.

• If more mechanical power is consumed than generated, it leads to a gradual reduction in speed due to decreased available energy.

Understanding Battery Pack Interactions

• The concept of regeneration involves understanding how energy flows between components: from battery to MCU and then to motor during acceleration.

• During vehicle motion on flat or downhill roads without acceleration, external forces cause rotation of tires which generates electricity through the motor back into the battery pack.

Summary of Regeneration Process

• In summary, when accelerating (throttling), energy flows from battery to motor; conversely, during deceleration or coasting downwards with no throttle input, energy flows back into the battery via regenerative braking mechanisms.

Understanding Regenerative Braking in Electric Vehicles

Overview of Throttle and Motor Control

• The discussion begins with the concept of starting a vehicle by turning on the key, which powers the motor at maximum speed. To control this speed, a throttle is implemented.

• A brake sensor is connected to the microcontroller unit (MCU), which plays a crucial role in managing power flow when brakes are applied.

Role of the Microcontroller Unit (MCU)

• The MCU receives signals from the brake sensor and is programmed to cut off power flow from the battery pack to prevent excessive current draw when braking occurs.

• When brakes are applied while throttling, it increases motor load; thus, cutting off power helps manage energy consumption effectively.

Transitioning Power Flow During Braking

• Upon pressing the brake, power to the motor is cut off. However, due to inertia, the motor continues running and acts as a generator.

• This transition allows energy generated by the motor during deceleration to be sent back to recharge the battery pack.

Dynamics of Vehicle Deceleration

• The speaker explains that applying brakes does not instantly stop a vehicle; instead, it gradually reduces speed from higher velocities like 80 km/h downwards.

• Both electrical and mechanical braking occur simultaneously during this process, utilizing energy generated by regenerative braking for recharging.

Importance of Energy Management

• The MCU's management ensures that when both throttling and braking actions occur together, only braking will be sensed while cutting off throttle input.

• This prevents potential damage from simultaneous power flows from both battery and motor into one system.

Advantages of Regenerative Braking System

• The advantages include minimized losses and increased energy efficiency due to effective management of energy conversion processes.

• By reducing wasted energy during acceleration or deceleration phases through proper sensor integration, overall system efficiency improves significantly.

Understanding Regenerative Braking Systems

Power Loss and Mechanical Efficiency

• The discussion begins with the concept of power loss in braking systems, emphasizing reduced mechanical loss due to the absence of friction.

• When brakes are applied, brake pads wear out; however, regenerative braking reduces pressure on mechanical brakes, leading to less wear.

• This results in higher braking life and efficiency, as mechanical losses are minimized.

User Experience Challenges

• The speaker highlights a potential user experience issue: when driving uphill, releasing the brake can cause the vehicle to roll back if not managed properly.

• In such scenarios, the Motor Control Unit (MCU) prevents power from flowing until the brake is fully released, which may frustrate drivers.

• While this design protects battery health and motor longevity, it poses challenges for user-friendliness during acceleration after braking.

Advantages of Regenerative Braking

• One significant advantage discussed is increased range due to reduced energy losses through regeneration.

• Enhanced mileage is another benefit attributed to regenerative braking systems that recover energy during deceleration.

Disadvantages of Regenerative Braking

• The speaker prompts participants to consider disadvantages alongside advantages. A key disadvantage mentioned is a decreased battery lifecycle due to simultaneous charging and discharging during regenerative processes.

• Lithium-ion batteries typically have a maximum cycle count (2000–2200 cycles), which can be negatively impacted by irregular charging patterns caused by regenerative braking.

Design Complexity and Cost Factors

• Another drawback noted is the complexity of design; frequent switching actions required by the MCU can lead to quicker aging of components.

• Despite these complexities, cost remains low since existing equipment suffices without needing additional systems for implementation.

• It’s emphasized that while regenerative braking enhances efficiency, it cannot solely stop a vehicle; traditional mechanical brakes remain essential for safety.

Operational Mechanism Overview

• The operational mechanism involves a simple circuit where pressing the brake switch sends signals to the MCU for immediate response in controlling power flow between battery and motor.

• Quick response times are crucial; any delay could compromise safety or performance when transitioning between acceleration and deceleration.

Regenerative Braking System and Internship Insights

Overview of Today's Learning

• The morning session focused on calculations related to a 50 kWh LFP battery pack, emphasizing the importance of understanding these calculations for practical applications.

• Participants were instructed to document their learning in an internship diary, detailing the selection process for Battery Management Systems (BMS) based on the calculations performed.

• In the afternoon, discussions shifted to regenerative braking systems, covering how they function and their advantages and disadvantages.

Regenerative Braking System Details

• Key aspects of regenerative braking include its operational mechanics, where power flow is managed between the battery, motor control unit (MCU), and motor during braking phases.

• The session highlighted that much of the learning involved practical calculations rather than theoretical concepts, reinforcing the significance of precision in engineering tasks.

Future Focus and Industry Relevance

• Emphasis was placed on solving problems related to battery pack design and BMS development as these areas have substantial industry demand and lucrative career opportunities.

• Participants were encouraged to focus on their core interests within this field to enhance their learning experience and future employability.