Converter reactor selection problem - Database & Sql Blog Articles

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When selecting an output reactor, several key factors must be considered to ensure optimal performance and system stability. First, the rated AC current is crucial. This represents the long-term operating current of the reactor, taking into account heat dissipation and harmonic content. The actual current flowing through the reactor typically corresponds to the output current of the inverter connected to the motor load. Next, voltage drop is an important parameter. It refers to the voltage loss across the reactor coil when the rated current flows at 50Hz. A typical range for voltage drop is between 4V and 8V, depending on the application requirements. Inductance is another critical factor. The rated inductance of the reactor plays a vital role in determining its performance under different loads. If the inductance is not properly chosen, it can lead to incorrect voltage drops and potential system malfunctions. The inductance value depends on the core cross-sectional area, the number of coil turns, and the air gap adjustment. The selection of inductance for an output reactor should be based on the cable length within the rated frequency range. Once the required inductance is determined, the core cross-section and conductor cross-section are selected according to the motor’s actual rated current to calculate the real voltage drop. Here is a reference table showing the relationship between cable length, rated output current, and corresponding inductance: - **300 meters** 100A → 46μH 200A → 23μH 250A → 16μH 300A → 13μH - **600 meters** 100A → 92μH 200A → 46μH 250A → 34μH 300A → 27μH An ideal reactor should maintain a constant inductance at or below the rated AC current. However, as the current increases, the inductance may decrease due to magnetic saturation. For example: - When the rated current exceeds twice the nominal value, the inductance may drop to 0.6 times the rated inductance. - If the current is more than 2.5 times the rated value, the inductance may reduce to 0.5 times the original. - At four times the rated current, the inductance could fall to as low as 0.35 times the rated value. Proper inductance selection ensures stable operation and protects both the motor and the inverter from damage caused by high-frequency harmonics and voltage fluctuations.