Project

# Title Team Members TA Documents Sponsor
81 Controllable, User-Friendly 3-Phase Inverter
 Alex Chirita
Johnathan Vogt
Shyam Peden
 Frey Zhao appendix1.png
appendix2.png
proposal1.pdf
proposal2.pdf
# Controllable, User-Friendly 3-Phase Inverter

Team Members:
- Johnathan Vogt (jsvogt2)
- Shyam Peden (speden2)
- Alex Chirita (chirita2)

# Problem

While normal 3-phase AC power systems operate with consistent phase differences of 120 degrees, these systems are not always perfect. There may be occasions (fault conditions) where the power system becomes unbalanced. In order to test small machines under these conditions, one might want to create controllable AC waveforms with adjustable phase angles.

# Solution

We will create an inverter system that is capable of creating three AC waveforms with controllable phase angles. Phase A will serve as the reference 0 degree phase, while the B and C phases will be controllable with respect to this reference phase. This will be achieved using analog control, likely via potentiometers. The PCB will function as a normal 3-phase switching inverter, with switching control handled by the microcontroller, which takes input from analog signals to control the output AC waveforms.

There will be 5 main subsystems : input stage with a boost topology, 3 MOSFET H-bridges, Encoder, CONFIRM button and small OLED Display as the user interface, and a TI-C2000 microcontroller as it has enough PWM channels and high resolution timers, whose firmware will include the user input control, and the power control for the bridge

# Solution Components

- Microcontroller TI-C2000 F2800157SPN
- Rotary encoder PEC11R-4215F-S0024
- Button 320E11BLK
- Display NHD-0420CW-AB3
- Power FETS G18N20T
- Low side FET Drivers DGD0211CWT-7
- High side FET Drivers 1EDN7550BXTSA1
- Power capacitors (for bridges)
- Low resistance resistors for shunts (Voltage, current sensing)
- Connectors
- Potentiometers for precision voltage division
- Inductor cores
- Copper wire
- Linear voltage regulators for low-power IC’s (78xx Series)

## Subsystem 1: Boost Stage

The main purpose of this project is the inverter stage, while the input is some sort of DC that mimics a solar panel. We will not focus on it being powered from a solar panel during the semester and leave it as a modification/addition to the inverter part for further development. The input voltage needs to be converted to a setpoint and fed into a common DC bus. This will be done with a half bridge boost converter. A good quality of this system is the freedom to choose which variables to control. The circuit will be able to respond to quick changes in input voltage, but this semester we will be using a constant DC power supply instead of a solar panel to reduce cost and complexity. Therefore the boost converter will be run by a switching algorithm with a fixed input voltage. Later the algorithm could be changed to an MPPT conversion if needed.

## Subsystem 2: H-bridges

The bridge subsystem will contain three MOSFET H-bridges, each corresponding to one of the phases. Each of the phases will have a similar layout since the control is only achieved by the gate signal which is fully generated by the microcontroller. We decided to go with an H-bridge because it’s a good middle ground between multi-level bridges and a half-bridge. The H-bridge will allow us to generate a good quality sine wave when averaged out and filtered.The sine wave will be generated from -Vmax to +Vmax, and the sign will be decided by using a proper pair of MOSFETS from the 4 available. Each mosfet will have a corresponding low side or high side gate driver, which will receive their PWM control signals from the microcontroller. Each phase will have an LC low-pass filter at the end to reduce switching harmonics.

## Subsystem 3: User interface

The user interface will consist of a display, encoder, and a confirm button. The user will use the encoder and confirm button to navigate the user interface where the phase angle will be set for phase B and C in relation to phase A, which is static. Users can also choose to use an autoset where the microcontroller will default to 120 degrees between each of the phases.

## Subsystem 4: Input control

The microcontroller will run polling input from the button and encoders, run a loop which checks whether the phase is within bounds (-180 to +180 degrees with respect to phase A) and override the proper variables variables, which will be used by the switching subsystem as target phase angle.

## Subsystem 5: Switching control

The constant loop will check the phase angle variables and calculate the expected voltage for each phase. It will then generate the PWM for each phase that matches the needed Vrms. The output voltage which first went into the resistor divider to fit within maximum operating voltage of the microcontroller will be collected as samples over the wave period, Vrms calculated and compared to the set Vrms after which the switching signals for each phase will be adjusted.

# Criterion for success

Our device will be considered successful if we can accurately display a 3-phase network on the oscilloscope. Each phase has to have the same amplitude and frequency as well as have the same phase angle between each phase as set by the user. Across all 3 phases the inverter should be able to output 0.83A of current (~100W) and each phase should be able to handle 0.33A (~40W). The output RMS voltage is 120V.

Resonant Cavity Field Profiler

Salaj Ganesh, Max Goin, Furkan Yazici

Resonant Cavity Field Profiler

Featured Project

# Team Members:

- Max Goin (jgoin2)

- Furkan Yazici (fyazici2)

- Salaj Ganesh (salajg2)

# Problem

We are interested in completing the project proposal submitted by Starfire for designing a device to tune Resonant Cavity Particle Accelerators. We are working with Tom Houlahan, the engineer responsible for the project, and have met with him to discuss the project already.

Resonant Cavity Particle Accelerators require fine control and characterization of their electric field to function correctly. This can be accomplished by pulling a metal bead through the cavities displacing empty volume occupied by the field, resulting in measurable changes to its operation. This is typically done manually, which is very time-consuming (can take up to 2 days).

# Solution

We intend on massively speeding up this process by designing an apparatus to automate the process using a microcontroller and stepper motor driver. This device will move the bead through all 4 cavities of the accelerator while simultaneously making measurements to estimate the current field conditions in response to the bead. This will help technicians properly tune the cavities to obtain optimum performance.

# Solution Components

## MCU:

STM32Fxxx (depending on availability)

Supplies drive signals to a stepper motor to step the metal bead through the 4 quadrants of the RF cavity. Controls a front panel to indicate the current state of the system. Communicates to an external computer to allow the user to set operating conditions and to log position and field intensity data for further analysis.

An MCU with a decent onboard ADC and DAC would be preferred to keep design complexity minimum. Otherwise, high MIPS performance isn’t critical.

## Frequency-Lock Circuitry:

Maintains a drive frequency that is equal to the resonant frequency. A series of op-amps will filter and form a control loop from output signals from the RF front end before sampling by the ADCs. 2 Op-Amps will be required for this task with no specific performance requirements.

## AC/DC Conversion & Regulation:

Takes an AC voltage(120V, 60Hz) from the wall and supplies a stable DC voltage to power MCU and motor driver. Ripple output must meet minimum specifications as stated in the selected MCU datasheet.

## Stepper Drive:

IC to control a stepper motor. There are many options available, for example, a Trinamic TMC2100. Any stepper driver with a decent resolution will work just fine. The stepper motor will not experience large loading, so the part choice can be very flexible.

## ADC/DAC:

Samples feedback signals from the RF front end and outputs the digital signal to MCU. This component may also be built into the MCU.

## Front Panel Indicator:

Displays the system's current state, most likely a couple of LEDs indicating progress/completion of tuning.

## USB Interface:

Establishes communication between the MCU and computer. This component may also be built into the MCU.

## Software:

Logs the data gathered by the MCU for future use over the USB connection. The position of the metal ball and phase shift will be recorded for analysis.

## Test Bed:

We will have a small (~ 1 foot) proof of concept accelerator for the purposes of testing. It will be supplied by Starfire with the required hardware for testing. This can be left in the lab for us to use as needed. The final demonstration will be with a full-size accelerator.

# Criterion For Success:

- Demonstrate successful field characterization within the resonant cavities on a full-sized accelerator.

- Data will be logged on a PC for later use.

- Characterization completion will be faster than current methods.

- The device would not need any input from an operator until completion.

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