Explain the principles of power electronics in electrical engineering. Discuss the operation and characteristics of power semiconductor devices, such as thyristors, MOSFETs, and IGBTs. Describe different types of power converters, including rectifiers, inverters, and choppers, and their applications in power supply systems, motor drives, and renewable energy systems. How do control techniques, such as pulse-width modulation (PWM) and voltage regulation, play a role in improving the performance and efficiency of power electronic systems?