WEEK 10
For this week, my focus on the designing part by part is the rectifier circuit. To do this first, we need to design the parameters for the rectifier which is the value of the capacitor, resistor and the ratio for the transformer.
As we already know, the rectifier will act as a converter to convert the AC voltage input to the DC output. The rectifier is one of the main components in the UPS system which function as a converter to convert the main AC line to the DC voltage. The rectifier is divided into 2 main type, which is the controlled and uncontrolled rectifiers and its depend on types of the switches used.
So, for this current project, I am using the uncontrolled rectifier which is using the diodes as the switches. Therefore, in order to check either the rectifier design is worked is by comparing the simulation with the theoretical calculation. first things first, we set the voltage ripple ratio is 0.02 and the value of the resistor, R, is set to 500 ohms. Then, with that, we can calculate the value for the capacitor.
Then, Figure 1 shows the enlargement for the rectifier waveform. The value of the ripple can be reduced by using the suitable value for the capacitor and the resistor used. From Figure 1, the voltage ripple from the simulation is,
The peak-to-peak ripple voltage from the theoretical calculation is 0.67V. Meanwhile, the value for the simulation design is 0.5V which is close to the theoretical.
Rectifier Design
WEEK 11
For this week, after designing the rectifier, I will go to the next step which is designing the inverter. As we know, the function of the inverter is to convert the input DC voltage to the output AC voltage.
An inverter is an electronic device to convert the DC input voltage to the AC output voltage. There are two types of single-phase inverters which are half-bridge inverters and full-bridge inverters. But for our design, we are using the Universal bridge block, which the active switches are the IGBTs switches.
Due to its easy handling capability, the inverter has been designed using universal bridge block and IGBTs as the active switches as the power electronics component. The figure below displays the simulation configuration of the single-phase sine wave inverter circuit that is modulated by unipolar PWM by using the PWM Generator (2-level). The main circuit's DC power supply voltage is 24 V, which is attached to a resistive inductive load via a universal bridge inverter circuit.
For the PWM Generator, This block diagram can choose unipolar or bipolar PWM modulation to control the single-phase full-bridge system. That arm is operated independently using the unipolar modulation. But for design, we use unipolar SPWM for a controller of the inverter.
Gantt chart for FYP-1 for Logbook
WEEK 12
In week 12, after designing the inverter configuration. I try to simulate after determined all the parameters involved. But in my inverter design, passive is included which is LC filter. The result for my simulation before the filter is,
with THD Voltage,
From the PWM generator, the parameters for the triangular carrier signal frequency are set to 5kHz, the reference signals frequency is 50Hz, and the modulation index, Mi is 0.8. The parameters settings of the universal bridge module are displays as below.
Then, the value for the LC filter is determined by using the cut-off frequency and we set the value of capacitor to 0.68mF. Thus, the value of our inductor is 0.1mH.