Group 18 Lucas Chokanis Daniel Ramirez Lloyd Harrison Philip Teten

 A Proposal from Researchers to Implement Their Algorithms  Design a Power Efficient Thermostat to Control a Vehicle’s Heating, Ventilation, and Air Conditioning (HVAC) Systems  Create a Control System That will Significantly Extend the Life-Cycle of a Vehicle’s Battery  Provide a Control System that is Feasible to adapt for Future Additions

 Ability to Detect Input: ◦ Temperature of the Vehicles Interior ◦ Temperature of the Evaporator ◦ 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

 Electrically Noisy Environment: ◦ Use of Parts that Meet Automotive Requirements  15 ft Transmission Lines: ◦ PMSM Motor Control ◦ Remote Temperature Sensors  Highly Intuitive Programming: ◦ Giving Researchers Ease of Understanding

 Voltage Recieved: ◦ 12 VDC to 15 VDC  Output to Motors: ◦ 12 VDC Three Speed with Separate Hi, Med, Low input ◦ 12 VDC On/OFF 12VDC motor. ◦ Linear 0-3.3V “ramp” speed command  Relays: ◦ Coil Voltage of 12 VDC  Microcontroller ◦ MSP430 ◦ C2000

ParametricsMSP430F2274-Q1TMS320F28030LM4F110B2QR Architecture16-bit32-bit Flash (KB)32 Frequency (MHZ) RAM (KB)112 GPIO I2C114 UART118 SPI/SSI124 ADC10-Bit/12 channels12-bit/16 channels12-bit/12 channels RatingAutomotiveStandard

The chosen microcontroller is the MSP430F2274-Q1 for the following reasons:  Ultra-Low power  Code Composer Studio IDE  Qualified for Automotive applications  Sponsor provided the MSP430 Target board and USB programmer  Temperature sensor

 Ambient temperature Sensor: ◦ Housed on main thermostat circuit board. ◦ Provides feedback to the user via LCD screen  Evaporator 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 evaporator is cooling. ◦ Prevents the evaporator from freezing over. ◦ Feeds data back to the MCU to be that will be used to improve efficiency.  Auxiliary Temperature Sensor: ◦ Remote sensor location (<15ft away from main board). ◦ Feeds data back the MCU to be used to improve efficiency.

ModelManufacturerAccuracy Temp. Range Current Draw OutputPrice $ LM35A Texas Instruments ±0.2ºC -40ºC to 110ºC 60µA Linear Voltage 5.60 LM35CA Texas Instruments ±0.2ºC -40ºC to 110ºC 60µA Linear Voltage ADT7420Analog Devices±0.2ºC -40ºC to 125ºC 265µA 16-Bit 4.87 ADT7320Analog Devices±0.2ºC -40ºC to 125ºC 265µA 16-Bit SPI 4.87 TMP100Texas Instruments ±3ºC-55ºC to 125ºC 45µA2.15

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.

 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.

 4 Digits 1 Decimal Accuracy

 Driver Uses Less Pin Outs  Good for Intuitive Programming B3B2B1B0LCD Display A 1011b 1100C 1101d 1110E 1111F D1D2D3D4Function 0000No Change 0001Store Data in Latch 4 to be Displayed in Digit Store Data in Latch 3 to be Displayed in Digit Store Data in Latch 2 to be Displayed in Digit Store Data in Latch 1 to be Displayed in Digit Store Data in All Data Latches, Display All

 4 Digits 1 Decimal Accuracy

 View Changing: Scroll Through

 Temperature Set for Nominal Setting

 Setting the Blower Motor State

Analog Out 0.165V to Settings

PWM Input

Lowpass Filter Eliminates High Frequency Components Maintains Analog DC Value w0 = 1/RC = 1kHz

Dual Differential Driver To Drive the 15’ of Cable Better Noise Immunity DO+1=DI1/2 DO-1 = -DI1/2

Shielded Twisted Pair Higher Noise Immunity Noise Cancels

Dual Differential Reciever R2OUT2 = (RIN2+) – (RIN2-)

Analog Out 0.165V to Settings

Solid-State Relays (SSRs) Vs. Electromechanical Relays: Relay TypeProsCons Solid-state  Faster switching times  Increased lifetime (no moving parts)  Bounceless switching  No sparking or arcing  Silent operation  Higher ON resistance (more power dissipated)  Small OFF resistance (small reverse leakage current)  Fails “short” Electromechanical  Lower ON resistance (ohmic contacts)  Higher OFF resistance (no current flow)  Fails “open”  Noisy  Shorter lifetime (10^5 to 10^7 switching cycles)  Switch bouncing  Arcing across contacts

Motor Control: Choosing Relay Current Rating DC Supply Voltage (V) LO-speed Current (A) MED-speed Current (A) HI-speed Current (A) Blower motor current draw (low, medium, and high speeds) Note: Highlighted values are interpolated values due to limitations in test equipment.

Motor Control: Choosing Relay Current Rating Condenser Fan Motor Current Draw DC Supply Voltage (V) Motor Current (A) Note: Highlighted values are interpolated values due to limitations in test equipment.

P/S section:3.3V5V Items Drawing Current 6.5 mA – MCU50 uA – LCD driver 795 uA – Temperature sensors (3 x 265uA) Total per section:10.8 mA50 uA Design current limit: 10 mA1 mA P/S efficiency:91 %84 % Current Draw

3.3V P/S EFFICIENCY 5V P/S EFFICIENCY

Load Supply Voltage (V) Supply Current (mA) 3.3V Output Current (mA) 5V Output Current (mA)Efficiency (%) Minimum Medium Maximum

Item PriceQuantitiyPaidTotal Microcontroller - MSP430F2274-Q1 Free Sample1Yes- Temperature Sensors - ADT7320 $ 4.873No $ PCB by 4PCB.com $ No $ LCD Display - Lumex LCD-S401C39TF Free Sample1Yes- LED for User Interface Owned8Yes- Push Buttons for User Interface $ 0.195No $ 0.95 Dual Differential Driver - DS90LV027AQMA Free Sample2Yes- Dual Differential Receiver - DS90LV028AQMA Free Sample2Yes- Shielded Twisted Pair - C ND $ Yes $ NPN transistor 200mA ICmax, 40V Vce(breakdown), through hole $ Yes $ 1.74 Switching Regulator - TI LM26003 Free Sample3 Yes - Relay automotive SPST 12V, 15A$1.796Yes $ Relay automotive SPST 12V, 30A$5.022Yes $ Capacitors $ $ Diode, Schottky 40V 30mA, through hole $0.665 Yes $ 3.30 Inductor 1mH, 10% through hole $2.793 Yes $ 8.37 Resistors $ Yes $ 6.79 TSSOP-20 to DIP-20 SMT Adapter (for TI LM26003 chip) $4.492 Yes $ 8.98 TOTAL $

 Noise from motors induced into MCU ◦ Possible Solutions: Filters, bypass capacitors, optocouplers  Multiple Temperature Sensors Sharing One SPI Interface.