Selection of inverter type

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Selection of Inverter Type To choose the appropriate type of inverter, it is first necessary to analyze the type of production machinery, its speed control range, static speed accuracy, and requirements regarding starting torque. Based on this analysis, a decision can be made as to which control method-based inverter is most suitable. By \"suitable\", it is meant that something should be both functional and cost-effective, on the premise of meeting the basic conditions and requirements of manufacturing processes and production. Table 1 shows the main performance characteristics and application areas of frequency converters under different control methods, while Table 2 presents the load characteristics and load torque characteristics of several common types of equipment, which can serve as a reference for selecting frequency converters. 　　Table 1: Main performance characteristics and application areas of frequency converters with different control methods Table 2: Load characteristics and load torque characteristics of several common types of equipment Continued: Classification of conventional frequency converters: (1) Classification based on the conversion circuit: 1. AC-DC-AC frequency converters first \"rectify\" fixed-frequency alternating current into direct current, and then \"invert\" that direct current into three-phase alternating current with an arbitrarily adjustable frequency. 2. An AC-AC inverter directly converts alternating current with a fixed frequency into alternating current whose frequency can be adjusted arbitrarily (the number of phases remains the same before and after conversion). (2) Classification based on the energy storage element (filtering method) in DC circuits: 1. Voltage-type inverters use capacitors as their energy storage elements. Medium and small-capacity frequency converters are mainly voltage-type frequency converters. 2. The energy storage element of a current-type inverter is an inductor coil. (3) Classification according to the voltage modulation method: 1. SPWM inverter – The voltage level is controlled by adjusting the pulse duty cycle. Almost all general-purpose frequency converters of medium and small capacity use this type of frequency converter. 2. Pulse Amplitude Modulation (PAM) inverters: The voltage level is achieved by adjusting the amplitude of the DC voltage. (4) Classification according to the number of phases of the input power supply: 1. Three-input three-output frequency converter – both the input and output sides of the frequency converter are three-phase AC power. The vast majority of frequency converters fall into this category. 2. Single-input three-output frequency converter: The input side of the frequency converter is single-phase AC power, while the output side is three-phase AC power. Inverters used in household appliances fall into this category, and they usually have a small capacity.