Project

# Title Team Members TA Documents Sponsor
72 Single-Phase AC Power Analyzer
 Isaac Herink
Jeffrey Pohlman
Joseph Kim
 Eric Tang other1.pdf
Team Members:
- Isaac Herink (iherink2)
- Jeffrey Pohlman (jpohl3)
- Joseph Kim (joseph51)

# Problem
Basic voltage and current measurements do not provide insight into how power is actually being consumed by an AC load. Relevant quantities such as real power and power factor require time-synchronized measurements of voltage and current, which are typically only available from commercial power analyzers. These commercial analyzers are expensive and unnecessary for small-scale laboratory or educational purposes.

# Solution
Design and build a microcontroller-based, single-phase power quality analyzer that measures voltage and current supplied to a load using isolated sensing circuits. The microcontroller will sample both signals at the same time and compute RMS values, real power, and power factor in real time. Measurement data will be transmitted to a computer over USB for display and analysis.

Example use cases include comparing real power and power factor across common loads (incandescent lamp vs. fan motor vs phone charger), measuring load startup behavior, and identifying inefficient or abnormal load behavior in educational lab experiments. It provides students with hands-on exposure to AC power measurements without needing expensive commercial equipment.

The final system will provide a low-cost, embedded tool for monitoring and analyzing AC power behavior in laboratory and educational environments.

# Solution Components

## Subsystem 1 - Power Path (Outlet -> Analyzer -> Load)

This subsystem will provide a safe way to place the analyzer in line with the load without the analyzer acting as the load. The load current will flow through internal wiring (with optional fuse protection), and the analyzer measures current using a CT. This subsystem ensures the analyzer itself does not significantly affect load current/voltage. It also ensures a simple connecting interface between the outlet, analyzer, and load.

Components:
Inlet/Outlet Wiring
Power Cord (McMaster Carr 71535K42),
Receptacle (McMaster Carr 1333N53),
Fuse (Littelfuse 0217005.MXP),
Fuse holder (Littelfuse 01550900Z).

## Subsystem 2 - Voltage Sensing

Provides an isolated low-voltage representation of the line voltage. The transformer secondary is routed to the PCB for conditioning.

Components:
AC Voltage transformer (120 VAC to 6-12 VAC) HQRP TR038 or equivalent.

## Subsystem 3 - Current Sensing

Provides an isolated current measurement to the load.

Components:
Split-core CT 5A to 5mA (B0G1M449JN) - We may use a CT with a larger secondary current.

Voltage and current sensing are isolated with a VT and CT to prevent direct electrical connection between mains and the MCU.

## Subsystem 4 - Analog Signal Conditioning

Converts VT/CT signals into clean and bounded voltages that the MCU can sample accurately. This subsystem performs:

- Voltage scaling: A resistor divider scales the VT secondary down to a target amplitude that is compatible with the ADC.
- Current to voltage conversion: A burden resistor translates the CT secondary waveform into a proportional voltage waveform (for ADC input).
- Input protection: Series resistors and clamp diodes to limit fault voltages and protect ADC ports.
- Filtering: RC low-pass filters to reduce high-frequency noise and prevent aliasing.

This subsystem ensures that the MCU receives waveforms that accurately represent line current/voltage.

## Subsystem 5 - Board Power

The PCB will be powered from USB 5V (or an external 5V source). A 3.3V regulator supplies the MCU.

Components:
Voltage regulator (Diodes Inc AP2112K-3.3TRG1)

## Subsystem 6 - Bias Voltage Generation

Both the voltage and current waveforms will be shifted (biased) to sit within the ADC input range, since the ADC cannot measure negative voltage. The PCB will supply a reference voltage of roughly 1.65V (Vmid = 1.65V) from the 3.3V rail using a resistor divider and decoupling capacitor. The conditioned waveforms are then centered around Vmid to remain between the 0-3.3V ADC range.

## Subsystem 7 - Embedded Processing (MCU)

A microcontroller will sample voltage and current channels at a fixed sample rate. The firmware will remove DC offsets, apply any needed calibration factors, and compute:
- RMS voltage/current
- Real power from the average of v[t]i[t]
- Apparent power, reactive power, and power factor

Components:
MCU (STMicroelectronics STM32F303CCT6 (LQFP-48)),
SWD programming header (Samtec FTSH-105-01-F-DV-K).

## Subsystem 8 - Communication and Display

This subsystem will present our computed values on a pc using USB serial (via a USB-UART bridge). A PC side program (Python or equivalent) will display Vrms, Irms, P, and PF over time.

Components:
USB-UART bridge (CP2102N),
USB connector (GCT USB4085-GF-A).

## Enclosure

We will design and 3D print an enclosure to contain our different subsystems. The enclosure will be self-contained and require only AC power and a USB connection.

# Criterion For Success

- Voltage and current waveforms are sampled at a fixed rate
- The device measures voltage and current simultaneously
- The device computes RMS voltage/current, real power, reactive power, and power factor
- Measurements are displayed on a PC in real time
- RMS voltage is measured within ±5% of a commercial analyzer for a resistive load
-RMS current is measured within ±10% for at least one load in the 0–5 A range
- Real and reactive power is computed within ±10% of a commercial analyzer for a resistive load
- Power factor is reported within ±0.10 and correctly distinguishes resistive (PF ~ 1) and inductive loads (PF < 1)
- The device is in a self-contained enclosure

Iron Man Mouse

Jeff Chang, Yayati Pahuja, Zhiyuan Yang

Featured Project

# Problem:

Being an ECE student means that there is a high chance we are gonna sit in front of a computer for the majority of the day, especially during COVID times. This situation may lead to neck and lower back issues due to a long time of sedentary lifestyle. Therefore, it would be beneficial for us to get up and stretch for a while every now and then. However, exercising for a bit may distract us from working or studying and it might take some time to refocus. To control mice using our arm movements or hand gestures would be a way to enable us to get up and work at the same time. It is similar to the movie Iron Man when Tony Stark is working but without the hologram.

# Solution Overview:

The device would have a wrist band portion that acts as the tracker of the mouse pointer (implemented by accelerometer and perhaps optical sensors). A set of 3 finger cots with gyroscope or accelerometer are attached to the wrist band. These sensors as a whole would send data to a black box device (connected to the computer by USB) via bluetooth. The box would contain circuits to compute these translational/rotational data to imitate a mouse or trackpad movements with possible custom operation. Alternatively, we could have the wristband connected to a PC by bluetooth. In this case, a device driver on the OS is needed for the project to work.

# Solution Components:

Sensors (finger cots and wrist band):

1. 3-axis accelerometer attached to the wrist band portion of the device to collect translational movement (for mouse cursor tracking)

2. gyroscope attached to 3 finger cots portion to collect angular motion when user bend their fingers in different angles (for different clicking/zoom-in/etc operations)

3. (optional) optical sensors to help with accuracy if the accelerometer is not accurate enough. We could have infrared emitters set up around the screen and optical sensors on the wristband to help pinpoint cursor location.

4. (optional) flex sensors could also be used for finger cots to perform clicks in case the gyroscope proves to be inaccurate.

Power:

Lithium-ion battery with USB charging

Transmitter component:

1. A microcontroller to pre-process the data received from the 4 sensors. It can sort of integrate and synchronize the data before transmitting it.

2. A bluetooth chip that transmits the data to either the blackbox or the PC directly.

Receiver component:

1. Plan A: A box plugged into USB-A on PC. It has a bluetooth chip to receive data from the wristband, and a microcontroller to process the data into USB human interface device signals.

2. Plan B: the wristband is directly connected to the PC and we develop a device driver on the PC to process the data.

# Criterion for Success:

1. Basic Functionalities supported (left click, right click, scroll, cursor movement)

2. Advanced Functionalities supported(zoom in/out, custom operations eg. volume control)

3. Performance (accuracy & response time)

4. Physical qualities (easy to wear, durable, and battery life)