Abstract : Frequency converters typically consist of a rectifier circuit and an inverter circuit. The converter circuit generates high-order harmonics due to its nonlinear characteristics. Interference from these high-order harmonics affects the normal operation of electrical equipment, and necessary preventative measures should be taken. Keywords: Transistor, Frequency converter, Harmonic interference, Anti-interference 1. Introduction to Frequency Converters With the rapid development of power electronics technology, power electronic equipment is increasingly widely used in ship power systems. The main content of power electronics technology is the use of power semiconductor devices for power conversion and control. Charge/discharge boards, uninterruptible power supplies, inverters, and other equipment in ship power systems all belong to converter circuits. The harmonic interference they generate is often overlooked because their power is relatively small or because there are few weak current devices in some ships. In recent years, technologies such as gate turn-off thyristors (GTOs), power transistors (GTRs), bipolar transistors (IGBTs), pulse amplitude modulation (PAM), and pulse width modulation (PWM) have been applied to ship power systems, enabling the high power of marine frequency converters. For example, the two bow thrusters (each with a motor power of 700kW) and two stern thrusters (each with a motor power of 400kW) on the 75mPSV turbine built in our factory are all controlled by frequency converters. A frequency converter typically consists of a rectifier circuit and an inverter circuit. The block diagram of the frequency converter for the 75mPSV is shown in Figure 1; this is a typical AC-DC-AC frequency converter. [b][align=center]For more details, please click: Harmonic Interference and Anti-interference of Frequency Converters[/align][/b]