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55 Solar Powered Rechargeable Battery Pack with Controllable Voltage Output
Zhuohang Cheng
Zihao Zhang
Bryce Smith design_review
Team Members:

Zhuohang Cheng (zcheng14)

Zihao Zhang (zzhng130)

Project Description:
This project involves a rechargeable battery pack with following features:
1. Will have a solar panel as power source which can constantly provide dc power to the battery pack when the user is doing outdoor activities.
2. Can also be charged by the power grid with 110V.
3. Can discharge AC or DC power with adjustable voltage level, from 5V to 25V DC, and from 20V to 120V AC.
4. Will have battery management system to indicate the voltage level, output current and charge/discharge condition.

Project Uniqueness:
The rechargeable battery packs are not user-friendly today. Most of them can only output one voltage level, and users need to buy extra voltage converter to fit their device. We would like our battery to output adjustable voltage level which could satisfy every device for our users. Also, it can provide constant power in daytime without concerns of out of battery.

Project Requirements:
For this project, we need to build a storage battery pack using several parallel-connected rechargeable batteries. Converters and inverters will be needed to regulate the input and output voltage. A portable box with surface-mounted solar panel provides the flexibility of outdoor activities. To monitor and control the discharging process, a microcontroller with display screen will be necessary for user interaction.

Control System and User Interface for Hydraulic Bike

Iain Brearton

Featured Project

Parker-Hannifin, a fluid power systems company, hosts an annual competition for the design of a chainless bicycle. A MechSE senior design team of mechanical engineers have created a hydraulic circuit with electromechanical valves, but need a control system, user interface, and electrical power for their system. The user would be able to choose between several operating modes (fluid paths), listed at the end.

My solution to this problem is a custom-designed control system and user interface. Based on sensor feedback and user inputs, the system would change operating modes (fluid paths). Additionally, the system could be improved to suggest the best operating mode by implementing a PI or PID controller. The system would not change modes without user interaction due to safety - previous years' bicycles have gone faster than 20mph.

Previous approaches to this problem have usually not included an electrical engineer. As a result, several teams have historically used commercially-available systems such as Parker's IQAN system (link below) or discrete logic due to a lack of technical knowledge (link below). Apart from these two examples, very little public documentation exists on the electrical control systems used by previous competitors, but I believe that designing a control system and user interface from scratch will be a unique and new approach to controlling the hydraulic system.

I am aiming for a 1-person team as there are 6 MechSE counterparts. I emailed Professor Carney on 10/3/14 and he thought the general concept was acceptable.

Operating modes, simplified:

Direct drive (rider's pedaling power goes directly to hydraulic motor)

Coasting (no power input, motor input and output "shorted")

Charge accumulators (store energy in expanding rubber balloons)

Discharge accumulators (use stored energy to supply power to motor)

Regenerative braking (use motor energy to charge accumulators)

Download Competition Specs:

Team using IQAN system (top right corner):

Team using discrete logic (page 19):