Cascade Inverters for High Power Switching Amplifier

In a sonar imaging system, the transducer is supplied with a higher voltage, converts the electrical waves into excited acoustic waves that will propagate over a longer distance. Upon reflection from an underwater object, the waves are received and processed to determine shape and size of the object

Project Title

Cascade Inverters for High Power Switching Amplifier

Project Area of Specialization

Electrical/Electronic Engineering

Project Summary

In a sonar imaging system, the transducer is supplied with a higher voltage, converts the electrical waves into excited acoustic waves that will propagate over a longer distance. Upon reflection from an underwater object, the waves are received and processed to determine shape and size of the object. Low voltage based generated acoustic waves cannot propagate farther and only detect obstacles in vicinity, having small detection range. Now the array of transducers to enable wide coverage of underwater objection detection needs high power.

A limiting factor is that the DC supply normally ranges below a 100 V when it comes to submarine, and therefore, a high voltage gain is required. For high power and high voltage gain we are using cascade inverters: considerations for design and development of power amplifier are:

• High power
• Low THD
• High Gain

Design and development of cascaded H-bridge will be completed through simulations using circuit analysis tools followed by hardware implementation. The purpose of this project is to develop a prototype for a switching Power Amplifier on the basis of the thorough literature survey being done by different scholars and researchers. It involves the following key functionalities and parameters:

BoM, PCB Schematic and Details about the project can be found in this google drive folder

Parameters

Gain (determined by switching frequency)

Central Frequency

Output power

Supply voltages

PCB Dimensions

Project Objectives

We have to produce an electrical signal with high power, high gain, and low THD to produce strong acoustic waves that travel farther for the detection of an undersea object. As a result, our mission statement is to meet the following goals:

• To obtain high power.
• To obtain high gain.
• To obtain low THD.

Project Implementation Method

We started with simulations of cascade inverters with a 400kHz output frequency using LTspice and generating output waveforms. These waveforms were compared and the results were verified. Along with the output frequency of 400kHz, simulations for the neighboring frequencies i.e., 350kHz and 450kHz were performed, and their respective outputs were generated.

A five-level output is generated by our cascade inverter. We utilized two H-Bridges with eight MOSFETs in cascade to get this five-level output. Each of these eight MOSFETs requires its own driving signal at its gate. As a result, FPGA Board is being used to generate the driving signals.

The hardware implementation was the next step after the simulations and generation of driving signals for MOSFET gates. For the hardware setup, we're designing a Printed Circuit Board (PCB) for our cascade inverters.  There'll be three primary stages on this PCB. The first is our power stage, which consists of Cascade Inverters that will power our load. Then there'll be the Driver Circuit stage.  This driver circuit will convert the control signals from FPGA into the driving signals that will be driving our power stage. This driver circuit will convert the control signals from FPGA into the driving signals that will drive our power stage. The last is the regulator stage which is designed to provide us with voltages that are required to power our driving circuit.

We'll start testing our hardware after our PCB has been designed and manufactured by the manufacturer. We'll start with regulator testing and after they clear, we'll provide power from this regulator stage to the driver stage. Following that, tests on these drivers will be carried out to see if the driving signals are generated in accordance with our specifications. We'll attach our power stage and run the remaining tests on our hardware once both the regulator and driver stage tests are successful.

We will compose our final write-up and thesis report once the testing process is completed.

Benefits of the Project

With the help of inverters, we're converting DC to AC. Furthermore, we improve power, gain, and total harmonic distortion (THD) at our load by using cascade inverter topology. In comparison to a single H-Bridge Inverter, this power is twice. Once we have high power at our load, we can use it in applications that require high power with high gain. Sonar imaging is one application in which the transducer's power determines the strength of the acoustic waves it generates. Strong acoustic waves will be generated if the transducer is given high power. These powerful acoustic waves would be capable of travelling long distances and detecting objects in their path. As a result of the increased transducer power, the imaging system becomes better and more effective.

When converting DC to AC, the THD value is also a critical aspect to consider in the AC output. single H-bridge inverter produces   Only three levels of output. This three-level output has a large THD and requires a lot of filtering to make it pure sinusoidal. THD is reduced when the number of levels in the output is increased, and this high-level output can then be transformed into true sinusoidal using a simple filter. Because suppressing one harmonic in the frequency domain adds one level in time domain, the waveform becomes increasingly sinusoidal without filtering, lowering THD. Different topologies are used to achieve the increase in the number of output levels. The cascade inverter topology is a sophisticated yet basic design. As a result, our cascade inverter will have a low THD, and we'll smooth it out using a filter to make it pure sinusoidal.

Technical Details of Final Deliverable

The underwater imaging application uses acoustic signals because of their ability to travel farther. An active sonar system is vital for submarine navigation, generating a sound burst and estimating the undersea object from the reflected waves. Since a piezo transducer translates the applied voltage to a sound wave, a power amplifier is essential as a preprocessor to ensure an interpretable echo. The distinctive characteristic of the problem arises from the fact that such transducers are predominantly capacitive. So, a class-D sonar amplifier designed and built to drive a particular acoustic transducer with a 50 ? impedance at a resonant frequency of 400 kHz. Because of its high efficiency and compact nature, the class-D has been chosen as the power amplifier topology over its linear counterparts.  Our cascade inverter is realized using MOSFETs IRFB4115 in a cascaded bridge arrangement. When triggered with driver Si8233 the bridge inverter generates a high-frequency square wave. The driver IC Si8233 will drive two MOSFETs, one high and one low-side MOSFET. So, we will use 4 driving ICs to drive 8 MOSFETs. FPGA generalized code will also be provided that can be altered for the user’s desired frequency of control signals. This code will generate controlling signals for the driver ICs that will further generate driving signals for MOSFETs.

Driving ICs need power for their regulation. So, we are using regulator LM7805 for providing 5V and LM350 for providing variable 10-12V. Fuses have been added to the input of regulars for safety purposes of the PCB. Reverse polarity protection is added to the H-Bridge for its protection. Consequently, the amplifier necessitates an impedance matching network (IMN) to guarantee that electrical power is transferred efficiently from the source to the load and also meets the additional constraint of restricting the output total harmonic distortion (THD). In addition, the proposed parallel IMN enables high voltage gain and solves the electromagnetic interference (EMI) noise issues. Thus, the gain of 2Vin and peak power of 500 W from low-voltage sources of 96 Vdc is ensured by employing a boost-type IMN. The simulation and experimental results will be analyzed at the end of project to show that the designed amplifier reduces power losses when operated in the inductive region and improves the THD and bandwidth.

Final Deliverable of the Project

HW/SW integrated system

Core Industry

Energy

Other Industries

Transportation

Core Technology

Robotics

Other Technologies

Others

Sustainable Development Goals

Life Below Water

Required Resources

If you need this project, please contact me on contact@adikhanofficial.com