Abstract: Power electronics technology, developed in the latter half of the 20th century, is a technology for converting and controlling electrical energy. It has become an important fundamental course for electrical engineering and automation majors. Faced with the increase in university courses and the decrease in teaching hours for professional courses, reforming teaching content, methods, means, and experimental teaching conditions is of great significance for improving teaching quality and cultivating innovative talents. Keywords: Power electronics technology; rectifier circuit; pulse arrangement; rectified output voltage I. Application of Power Electronics Technology Power electronics technology is an emerging technology, formed by the intersection of three disciplines: electrical engineering, electronics, and control theory. In electrical automation majors, it has become an indispensable fundamental course with strong professional foundation and close ties to production. This course embodies the control of high-voltage electricity by low-voltage electricity and has strong practical application. It connects theory with practice and occupies an important position in cultivating automation professionals. It covers the structure and classification of thyristors, overvoltage and overcurrent protection methods for thyristors, controlled rectifier circuits, active thyristor inverter circuits, passive thyristor inverter circuits, PWM control technology, AC voltage regulation, DC chopping, and the working principles of frequency converter circuits. Controlled rectifier circuits are a crucial chapter in power electronics technology. Rectifier circuits convert alternating current (AC) to direct current (DC), and their applications are extremely wide-ranging. Speed ​​control of various DC motors widely used in industry employs power electronic devices; rectifier power electronics technology is also widely used in electrified railways (electric locomotives, maglev trains, etc.), electric vehicles, airplanes, ships, elevators, and other transportation vehicles; various electronic devices, such as the DC power supplies used in program-controlled exchanges in communication equipment, the operating power supplies required by large computers, and the internal power supplies of microcomputers, can all be powered by DC power supplies constructed from rectifier circuits. In short, wherever there is power, there are devices using power electronics technology. II. Rectifier Circuits in Power Electronics Technology Course Rectifier circuits can be classified into three types according to the components they use: uncontrolled, semi-controlled, and fully controlled. Semi-controlled and fully controlled rectifier circuits are mainly constructed using thyristor semiconductor devices. They can also be classified into bridge and zero-type rectifier circuits according to their wiring method. Furthermore, they can be classified into single-phase and multi-phase (mainly three-phase) rectifier circuits according to the number of AC input phases. Based on the learning patterns of students, and to present the knowledge points completely, accurately, and concisely, and to simplify, popularize, and visualize the principles as much as possible, the author has explored and researched this topic in teaching. Based on the circuit characteristics and load types of the three types of rectifier circuits, the author has created summary tables for single-phase rectifier circuits (see Table 1) and three-phase rectifier circuits (see Table 2), respectively, outlining the main parameter calculations and key features. In the table, α—control angle of the rectifier circuit, UFM, UKM—maximum forward and reverse voltages the thyristor can withstand, U2—effective value of transformer secondary voltage, U4—average output voltage, I4—average output current, IT—effective value of thyristor current, and Cosθ—power factor of the circuit. III. Summary and Induction of Rectifier Circuits in Power Electronics Technology Through the summary table, students can learn about the following aspects of rectifier circuits through comparative learning: (I) Requirements for Pulse Arrangement in Various Circuits This is the most important point, because the correctness of the pulse arrangement is crucial for the normal operation of a rectifier circuit. For a single-phase circuit, a cycle is 360°. If the circuit is a half-wave, it consists of one thyristor, and a pulse is sent every 360°. If the circuit is a half-controlled bridge, it consists of two thyristors and two diodes, and a pulse is sent every 180° (360°÷2=180°). If the circuit is a fully controlled bridge, it consists of four thyristors, working in two groups, and like the half-controlled bridge, a pulse is sent every 180° (note that "once" here means sending a pulse to two thyristors simultaneously). For a three-phase rectifier circuit, the number of power supply phases is three times that of a single-phase circuit, so the pulse arrangement is 1/3 times that of a single-phase circuit. For example, a three-phase half-wave circuit sends a pulse every 120° (360°÷3＝120°). A three-phase fully controlled bridge consists of six thyristors, which conduct in turn. It is necessary to ensure that two thyristors conduct at the same time, so a pulse is sent every 60° (360°÷6=60°), simultaneously to two thyristors. In the table, α—rectifier circuit control angle, UFM, UKM—maximum forward and reverse voltages the transistor can withstand, U2—effective value of transformer secondary voltage, I2—effective value of transformer secondary current, Ud—average output voltage, Id—average output current, IT—effective value of transistor current, θ—transistor conduction angle. (II) Calculation of the average output voltage of the rectifier circuit The output voltage of the rectifier circuit refers to the average voltage output by the circuit. This parameter reflects the magnitude of the circuit output and is usually used to select the rectifier circuit, making it a very important parameter. To help students remember the formula for calculating the output rectified voltage, the table shows that for a single-phase rectifier circuit, regardless of whether the load is resistive or inductive, the output voltage can be expressed as Ud = AU²(1 + Cosα)/2, where A is a coefficient. For a single-phase half-wave rectifier, A = 0.45; for a single-phase bridge rectifier, A = 0.9 (twice that of a half-wave rectifier). Only a single-phase fully controlled bridge rectifier with an inductive load is a special case, where the output voltage is Ud = 0.9u²Cosα. Similarly, for a three-phase rectifier circuit, when the Ud waveform is continuous (meaning there is a rectified voltage output throughout one cycle, without Ud = 0), the output voltage Ud = AU²Cosα. A is a coefficient. When the circuit is half-wave, A=1.17; when the circuit is a fully controlled bridge, A=2.34 (twice that of the half-wave). Only the three-phase half-controlled bridge is a special case, and its output voltage is Ud＝2.34U2（1+Cosα）/2. (III) Calculation of the average value of the rectifier circuit output current Whether it is single-phase or three-phase, whether it is a resistive load or an inductive load, the output current of the rectifier circuit is Id=Ud/Rd (Rd is the resistance value in the load). (IV) Calculation of Maximum Forward and Reverse Voltage Withstandable by the Thyristor This parameter is an important factor in selecting a thyristor. As shown in the table, for a single-phase rectifier circuit, the maximum voltage the thyristor can withstand is the peak value of the power supply phase voltage, i.e., √2U[sub]2[/sub], while for a three-phase circuit, the maximum voltage the thyristor can withstand is the peak value of the power supply line voltage, i.e., √6U[sub]2[/sub] (because it is three-phase, the line voltage differs from the phase voltage by √3 times). (V) Continuity of Output Voltage Ud Waveform As shown in Table 1, for a single-phase rectifier circuit, when the thyristor control angle α > 0°, the waveform of ud is discontinuous. Only with a single-phase fully controlled bridge inductive load, when α > 90°, the waveform of ud is discontinuous. Similarly, as shown in Table 2, for a three-phase rectifier circuit, the three-phase half-wave circuit has α = 30°. As the dividing point between whether the output voltage waveform is continuous or not; while the three-phase bridge rectifier circuit (including the half-controlled bridge and the fully controlled bridge) uses α = 60° as the dividing point between whether the output voltage waveform is continuous or not. The calculation rules of other parameters can also be found from the table, but due to space limitations, they will not be listed here. IV. Conclusion Through this set of summary tables of single-phase and three-phase rectifier circuits, students can quickly master the structure, circuit characteristics, and relevant calculation formulas of various rectifier circuits under different loads, which provides a good help for better mastering the basic theoretical knowledge of power electronics technology. References: [1] Zhao Dianjia. Thyristor Circuit [M]. Beijing: Metallurgical Industry Press. 1980. [2] Wang Zhaoan. Power Electronics Technology (4th Edition) [M]. Beijing: Machinery Industry Press. 2006. [3] Liu Yudi. Power Electronics Technology and Application [M]. Xi'an: Xi'an University of Electronic Science and Technology Press, 2006. [4] Jin Haiming. Power Electronics Technology [M]. Beijing: Beijing University of Posts and Telecommunications Press, 2006. For details, please click: A Brief Discussion on Rectifier Circuits in Power Electronics Technology.