Converter reactor selection problem - Database & Sql Blog Articles

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When selecting an output reactor, it's essential to consider several key parameters to ensure optimal performance and system stability. First, the rated AC current should be carefully chosen based on the long-term operating conditions of the system. This involves accounting for high-order harmonic components that may be present in the load, as they can significantly affect the actual current flowing through the reactor. The rated current is typically determined by the motor’s output from the inverter. Next, voltage drop is a critical factor. It refers to the voltage lost across the reactor coil when the rated current is applied at 50Hz. A typical range for this voltage drop is between 4V and 8V, depending on the application requirements and system design. Choosing the right voltage drop ensures efficient operation without excessive power loss. Inductance is another vital parameter. The rated inductance of the reactor directly influences the voltage drop under the rated current and plays a crucial role in maintaining stable system performance. The inductance value depends on factors such as the core cross-sectional area, the number of coil turns, and the air gap adjustment. Proper inductance selection helps prevent malfunctions caused by unstable current flow. The inductance of the output reactor should be selected based on the length of the cable within the rated frequency range. Once the cable length is known, the core cross-section and conductor size are determined according to the motor’s actual rated current. This process ensures that the actual voltage drop is within acceptable limits and supports reliable system operation. Here is a reference table showing the relationship between inductance, cable length, and rated current: | Cable Length (m) | Rated Output Current (A) | Inductance (μH) | |------------------|--------------------------|------------------| | 300 | 100 | 46 | | 200 | 23 | | | 250 | 16 | | | 300 | 13 | | | 600 | 92 | | | 200 | 46 | | | 250 | 34 | | | 300 | 27 | | An ideal reactor maintains a constant inductance at the rated AC current and below. However, as the current increases, the inductance tends to decrease. For example, when the rated current exceeds twice the nominal value, the inductance drops to 0.6 times the rated inductance. If the current goes beyond 2.5 times, the inductance reduces to 0.5 times the rated value, and at more than four times the rated current, it falls to just 0.35 times the original inductance. This behavior must be considered during the design phase to avoid saturation or instability in the system.