I. Introduction
In my country's power, petrochemical, mining, metallurgy, and water supply and drainage sectors, fans and pumps are among the most widely used and energy-intensive production machinery, with the vast majority requiring variable load operation. In today's increasingly energy-constrained world, replacing conventional fixed-speed drive systems with efficient, adjustable-speed motor drive systems would undoubtedly save significant energy. Furthermore, adjustable-speed drive systems offer soft-start capabilities, enabling fans and pumps to start smoothly and avoiding grid and mechanical shocks caused by direct motor starting, thus preventing a series of related accidents. Currently, many small and medium-power fans and pumps utilize low-voltage variable frequency speed control, achieving excellent energy-saving results and are being widely adopted. Therefore, exploring suitable high-voltage, high-power asynchronous motor speed control technology remains a hot research topic both domestically and internationally. The following section will introduce the main research progress in high-voltage frequency converter topology and switching modulation strategies.
II. Topology
With the rapid development of power electronic devices and microcontrollers, the topology of high-power power electronic devices has also made great progress. However, to date, high-voltage frequency converters do not have a nearly unified topology like low-voltage frequency converters. There are various classification methods for high-voltage frequency converter topologies both domestically and internationally. This paper adopts a new classification method based on whether the circuit topology shares a DC bus, revealing the inherent connections and differences between various topologies from the perspective of circuit configuration. According to this classification method, two-level frequency converters with multiple transistors directly connected in series, diode-clamped multilevel frequency converters, and flying capacitor-clamped multilevel frequency converters belong to the same category; these topologies all share a DC bus. Cascaded multilevel frequency converters belong to another category, requiring multiple independent DC buses for power supply.
For detailed information, please click: High Voltage Frequency Converter Topology and Control Strategy
