1: Choosing an over-voltage level can lead to unnecessary costs and longer payback periods. When the voltage level is too high, it increases the insulation requirements of the motor, which raises its cost. Additionally, higher voltage levels require more power semiconductor devices connected in series within the inverter, further increasing the overall system cost. This makes it highly inefficient and impractical to use 6kV or 10kV voltage levels for motors ranging from 200 to 2000 kW. 2: The relationship between inverter capacity and the phase number of the rectifier device is crucial. When connecting an inverter to a 6kV grid, it must comply with national regulations on harmonic suppression, which depends on the grid's short-circuit capacity and the unit’s rated power. For grids with a short-circuit capacity less than 1000MVA, a 12-phase configuration (with double windings on the transformer secondary side) can be used for a 1000kW device. If the capacity reaches 2000kW, a 24-phase system can significantly reduce the amplitude of the 5th and 7th harmonics. However, when the number of phases exceeds 36, the reduction in harmonic current becomes minimal, and the manufacturing cost rises sharply. In grids with a short-circuit capacity of 2000MVA, larger capacity devices are allowed. 3: Lowering the maximum voltage below 3kV can result in significant cost savings. It's important to consider the voltage level based on the characteristics and safety factor of power electronics. Due to the voltage limits of power electronics and the dv/dt constraints of motors, a 6kV inverter typically requires a multi-level structure or multiple devices connected in series, leading to complex wiring, higher costs, and reduced reliability. For example, using 1700V IGBTs, the American Robincon PERFECTHARMONY series 6kV inverter uses five 690V power units per phase connected in series, totaling 60 devices across three phases. Using 3300V devices would require three strings of 30 units each, which is even more complex. Moreover, the device current is small, and the current capability isn’t fully utilized. A 560kW motor, for instance, draws only about 60A at 6kV, while the 1700V IGBT can handle up to 2400A and the 3300V device up to 1600A. It's inefficient to use many small devices in series. Even for a 2000kW motor, the current remains low at around 140A. Foreign medium-voltage inverters come in various voltage levels such as 1.1kV, 2.3kV, 3kV, 4.2kV, and 6kV, primarily determined by the voltage capabilities of power electronics. For inverters delivering the same power, using a higher voltage or more units in series results in higher costs compared to using a lower voltage, fewer units, and larger current-rated components. Therefore, it's generally more efficient and cost-effective to choose a lower voltage level whenever possible. High Frequency Flyback Transformer RM10 electrical transformer,EE13 high frequency transformer,EE10 LED transformer,EE16 flyback transformer IHUA INDUSTRIES CO.,LTD. , https://www.ihuagroup.com