In this chapter, we present a novel control strategy for a single-phase cascaded H-bridge multilevel inverter in a grid-connected solar PV system. Unlike the known grid-connected inverters controls using a DC/DC converter for the MPPT pursuit, our control technique offers an MPPT algorithm for each PV module by handling its corresponding inverter only. The inverter connection of the grid is made through an LCL filter due to its ability to reduce harmonics instead of a simple inductance filter. To relieve the resonance phenomenon through the capacitors and inductors, a passive damping resistor is connected in series with the capacitor. We have used both controllers PI and PR, respectively, on the synchronous reference frame dq and the stationary reference frame αβ. The main purpose is to eliminate significant harmonics (3rd, 5th, and 7th) using our novel controller in order to improve the quality of the injected energy into the grid. By controlling the active and reactive power, we have proved that the PI controllers cannot track the sinusoidal references without a steady error in the synchronous reference frame dq. Furthermore, the PR controller has better performances and is more interesting for controlling the DC/AC converters. Indeed, in the stationary reference frame αβ, the PR controller gives a static error near zero for sinusoidal currents. Moreover, injected current quality improvement due to the most dominant odd harmonics elimination (3rd, 5th, and 7th) is insured by the HC. The adequate drive pulses are generated by a proportional modulator algorithm.

Single-Phase Grid-Connected Photovoltaic H-Bridge N-Level Inverter Control Strategy

This paper mainly focusses on the steps for designing cascaded multi-level inverter. The multi-sine pwm technique is implemented which can control the output voltage by varying the amplitudes of two modulating signals. The approach of designing i.e. important features for selecting the controller, bipolar IGBT driver circuit design with an optical isolation, low voltage isolated power supplies for bipolar driver cards and high voltage isolated power supplies for each H-bridge, importance of delay circuit in inverters and design procedure for selecting minimum LC filter size to eliminate harmonics in load as per IEEE-519. The performance analysis and results are verified with MATLAB Simulink and hardware circuit.

Hardware Design of Cascaded Multi-Level Inverter using Multi-Sine PWM Technique

Induction motors are extensively used motor type for various industrial applications for the reason that they are robust, simple in structure, and efficient. On the other hand, induction motors are prone to different faults during their lifetime due to hostile environments. If the fault is not detected in its rudimentary phase, it may cause unexpected shut down of the entire system and colossal loss in industry. It is conspicuous that scope of this field is huge. This work presents detection of internal and external faults of induction motor. S-Transformation, which is superior as compared to CWT and STFT as it does not contain any cross terms, is used for bearing fault detection, and random forest, an algorithm which is easy to implement and requires minimum memory, is used for detection of external faults. The fault can be detected with more accuracy in premature state leads to improve the reliability of the system.

Ruhul Amin Choudhury

Papers

Hardware Design of Cascaded Multi-Level Inverter using Multi-Sine PWM Technique

Induction Motor Internal and External Fault Detection