General Purpose Power Electronic Converter

Create a control algorithm to integrate four each 15kW units to function as a continuous 60kW unit.

Background
The final goal of our project is to create a high efficiency programmable power electronic converter. Since it is difficult to get the eventual accomplishment, our team decides to do some early research for this project. Our clients hope that the input and output values can be adjusted between 100V and 600V; also, the efficiency should be at least 94%. In addition, Overcurrent protection and Overvoltage protect is required Due to safety reason, we starts with smaller input values and output value. Also, we decides to research forward converter for this project. The forward converter is a DC/DC converter that uses a transformer to increase or decrease the output voltage and provide galvanic isolation for the load. With multiple output windings, it is possible to provide both higher and lower voltage outputs simultaneously.

Design Goals
Power-Panda team has decided to adopt forward converter for the project. Full-bridge converter is abandoned by us. The first goal of this project is that building a real forward converter to test and verify our schematic is correct. If the real converter can work correctly, we will build an integrated forward converter (2 single forward converter integrated) In addition, after finishing building integrated forward converter, we will create a control algorithm for it.

Specifications
input voltage source: 12-36V  (adjustable values) output voltage values: 24V(fixed values) Output power 100W converter The intergraded converter should provide 400 W power(4 DC-DC), and the efficiency should be equal or higher than 94%. Our converter should be placed on a breadboard One single converter range :8cm x 15cm integrated converter range :32cm x 60cm

Project Learning
The most interesting characteristic is that we decided to use CHIP LT8310.We can avoid some defects when we use the forward converter with chip.The traditional forward converters have low efficiency; also, it is hard to create simulation schematic. LT8310 chip can bring High efficiency and short-circuit overcurrent protection for us. While we were creating simulation of forward converter, we found that the diode is the key to get high efficiency. We do not use the diodes that LTspice offers because we design our diode by ourselves which means the inner parameters of diode were added by our team. Our future research will focus on: 1.How to increase max efficiency in integrated forward converter 2.How to increase max efficiency at each point (from 0 to 400W) 3.Control Algorithm 4.Load balancing by using economic dispatch

Designs
Circuit of Forward Converter

V1 is input voltage source. L1 and L2 mean transformer. RB068L152 is the diode the design by our team(this is the key component to keep efficiency high) diode parameters: 1. BV=500 breakdown voltage 2. N=0.35 emissive coefficient 3. Is=14.11n saturation current 4. Rs= 2.2m  series resistance 5. Cjo=40p  Zero bias junction capacitance 6. M=0.5   Nodal gradient factor 7. tt=25n  crossing time 8. Iave=20 positive rated current 9. mfg=Huawei manufacturer 10. type=silicon material Rload is load resistor. R4 & R5 are feedback resistors R3 is Rsense R13, R14 and R15 are estimated values. UVLO and OVLO: the system undervoltage and overvoltage thresholds are programmed by a resistive voltage divider from Vin to UVLO and OVLO. Rt controls frequency. R1&C2 control duty cycle. C3 means soft-start input(this value is not very important) the secondary part is the same as our ECE 320 textbook, so there is no detailed description. However, their calculation equations are given in the next part.

Design Procedures
1 Choose a type of DC-DC converters(Our team chooses Forward & Full Bridge)

2 Make Simulation of Converters

3 Do some calculations about efficiency

4 Create a real circuit and test the circuit

5 Create Control Algorithm to find the highest efficiency

Project Budget
 

Content of meeting