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Experimental Engineering Thermal Control System (EETCS). Group 18 Lucas Chokanis Daniel Ramirez Lloyd Harrison Philip Teten. Motivation. A Proposal from Researchers to Implement Their Algorithms
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Experimental Engineering Thermal Control System(EETCS) Group 18 Lucas Chokanis Daniel Ramirez Lloyd Harrison Philip Teten
Motivation • A Proposal from Researchers to Implement Their Algorithms • Design an Experimental Thermostat to Control a Vehicle’s Heating, Ventilation, and Air Conditioning (HVAC) Systems • Provide a Control System that is Feasible to adapt for Future Modifications
Objectives • Ability to Detect Input: • Temperature of the Vehicles Interior • Temperature of the Blower Motor • Extra Temperature Sensor for Researchers Use • Control Output: • Speed of the Blower Motor (High, Med, & Low) • Speed Command of the PMSM Motor • Condenser Fan • Clutch Control • Implement a User Interface • LCD Screen and LED’s for Feedback • Push Buttons for User Control
Challenges • Electrically Noisy Environment: • Use of Parts that Meet Automotive Requirements • 15 ft Transmission Lines: • PMSM Motor Control • Two Remote Temperature Sensors • Highly Intuitive Programming: • Giving Researchers Ease of Understanding • Communicating Multiple Temperature Readings Via SPI Bus
Specifications and Requirements • Voltage Received: • 12 to 15 VDC • Output to Motors: • 12 VDC Three Speed Blower Motor Control • High, Medium, Low • 12 VDC Condenser Fan • 12 VDC Clutch Control • Linear 0 to 2.63 VDC “Step” Speed Command • Relays: • Four 15 Amp Relays • One 30 Amp Relay • Coil Voltage of 12 VDC • Microcontroller • MSP430 or C2000
Microcontroller The chosen microcontroller is the MSP430F2274-Q1for the following reasons: • Ultra-Low power • Code Composer Studio IDE • Qualified for Automotive Applications • Sponsor provided the MSP430 Target board and USB programmer
Temperature Sensors • Ambient temperature Sensor: • Housed on main thermostat circuit board. • Provides feedback to the user via LCD screen • Blower Motor Temperature Sensor: • Remote sensor location. • 15ft away from main board as required by the customer. Its purpose is to keep track of the rate at which the blower motor is cooling. • Auxiliary Temperature Sensor: • Remote sensor location (<15ft away from main board).
Temperature Sensors The chosen temperature sensors were the ADT7320 for the following reasons: • Very high accuracy rating on a wide temperature scale. • We can expect reliable temperature readings in a cold environment such as the evaporator. • User programmable with multiple features • Temperature resolution up to 16-bits.
Temperature Sensors Communication • Extending The SPI Bus for Long Distance Communication: • For the remote sensors, it is possible that propagation delay could be significant enough to hinder data transmission. • Once we attempt to conduct SPI communications at distances greater than 15 feet, we will know if propagation delay will require a hardware solution. • If this turns out to be the case, dual differential transceivers will be used to refresh the clock signal protect the data transfer from noise. • If the signal is fed back to the master from the slave, data transmissions between the master and slave will occur at the same delayed clock signal.
Sensor Initialization • Although the ADT7320 sensor performed above our expectations, we realized that an initialization subroutine was required for it to function reliably.
User Interface • 4 Digits 1 Decimal Accuracy
LCD Display and Driver • Driver Uses Less Pin Outs • Good for Intuitive Programming
User Interface • View Changing: Scroll Through
User Interface • Temperature Set for Nominal Setting
User Interface • Setting the Blower Motor State
Motor Control Solid-State Relays (SSRs) Vs. Electromechanical Relays:
Motor Control Motor Control: Choosing Relay Current Rating Blower motor current draw (low, medium, and high speeds) Note: Highlighted values are interpolated values due to limitations in test equipment.
Motor Control Motor Control: Choosing Relay Current Rating Condenser Fan Motor Current Draw Note: Highlighted values are interpolated values due to limitations in test equipment.
Power Current Draw
Power 3.3V P/S EFFICIENCY 5V P/S EFFICIENCY
Power Regulator Efficiency