Cordless Electric Nailer Team 27: Nithin Reddy and Mohammad Farooq Shaik Ece 445 Senior Design Project Team 27

Introduction A battery powered nailer will provide the user with a sense of portability that current models do not. Our goal is to develop an efficient DC motor controller for the mechanical component of the nailer.

Objectives Design a low powered DC motor Controller. Inexpensive. Develop enough energy to drive a nail. Create a battery monitoring system.

System Specifications Input: 10-18 Vdc Output: 15 Vdc ±2% Power Ratings: 250W Continuous 500W Peak for 1 minute

System Outline Power Supply Battery Charge Display PWM UC 3825 Buck Converter Mechanical Component H-Bridge Driver LS 7260 H-Bridge DC Motor Control Module Voltage Regulator Module

Battery Charge Display Consists of 3 LEDs Green – Battery is full. Yellow – Battery is 60-70% full. Red – Battery is getting low Variable resistors can adjust the thresholds of the 3 LEDs

Battery Charge Display Testing Circuit was tested by applying a variety of voltages. The respective LED lights up for the voltage applied. If the LED did not light up, it was tested to see if the LED was faulty.

Battery Charge Display Vo >14.5 volts 14.5 V> Vo > 12.5 V 12.5 V> Vo Vo = Battery voltage

Control Module Pulse Width Modulation (UC3825) Compares the output voltage from the voltage divider circuit to the internal reference and adjusts the duty cycle accordingly. H bridge driver (LS7260) Direct drive control of MOSFETs. Controls direction of DC motor. Ability to stop the motor at any instant.

Buck Converter Step down DC-DC converter. Maintains constant output of 15 volts. Simulated Boost Converter Output

Buck Converter Testing Tested the buck converter circuit with varying voltages. Ensured that the output voltage was 15 volts regardless.

H Bridge 4 MOSFETS( 2 P type and 2 N type). 2 MOSFETS are on at one time. Controls the direction of the motor.

H Bridge When S1 and S4 are on, the motor moves in an anticlockwise direction When S2 and S3 are on, the motor moves in a clockwise direction

Mechanical Component Currently being created by mechanical engineering senior design team Motor will rotate and will cause spring to compress and expand. Expanded Spring Collapsed Spring

Successes Battery powered. Low Power Requirement. Inexpensive. Ability to control motor direction.

Difficulties Speed control of the DC motor with the PWM chip. Winding of the Inductor. Searching for high current resistant MOSFETS. Understanding Chip Functionality.

Recommendations Finalize circuit design before submitting a PCB request. Obtain compatible high power motors to test at desired power levels. Use Power Lab: Less crowded, Familiar Equipment and access to motors. PCB layout to improve efficiency and avoid parasitics (stray capacitance and inductance).

Questions?