Direct high-voltage inverter drives medium and low voltage motors more economical

Design of the fan frequency conversion speed control system The high-voltage frequency converter is divided into two types: intersection-intersection mode and AC-straight-intersection mode. At the same time, the AC-DC-AC mode can be divided into high-low-high mode and high. - Low mode and high-high mode. 1) Cross-over mode. This is a relatively high-voltage inverter that appears earlier. It consists of multiple power devices. The main circuit switching device is in a natural shutdown state. It can meet the requirements with ordinary thyristor devices. However, due to structural defects, the output current harmonics are high. Reactive power compensation and filtering, so that the overall equipment efficiency is reduced, the cost is increased, so it is suitable for the speed regulation of high-power, low-speed transmission equipment; 2) high-low-high mode. The high voltage of the power grid is reduced to low voltage through the frequency converter, and then the general frequency converter is used for frequency conversion, and the high voltage motor is driven by the booster frequency converter to rise to high voltage; 3) high-low mode. That is, the high voltage of the power grid is reduced to a low voltage through the step-down transformer, and then a high-voltage inverter with a low voltage or a low voltage level is selected to drive the motor with the same voltage level as the inverter.

In the case of the same motor capacity, this solution is more economical than the direct high-voltage inverter driving medium and low-voltage motors; high-high mode. This method is a direct high-voltage mode. The inverter directly changes the high voltage in the power grid to a frequency-adjustable voltage without the step-down and step-up transformer. The energy-saving effect of the high-frequency frequency conversion of the discharge machine is ideal according to the characteristics of the parameters of the distribution machine and the economic factors. Will produce the following effects: 1) saving energy. Set the frequency converter to use the /h motor frequency modulation when the high pressure manifold pressure is used to eliminate the return flow and save energy; 2) The operation is more stable. Due to the automatic pressure adjustment, the outlet pressure of the discharge machine can be kept in the set state (34000pa~36000pa), and the monitoring is more comprehensive, which improves the safety of the system; 3) the maintenance cost is reduced. Due to the low speed, the life of many spare parts is extended accordingly, which saves maintenance costs. 4) The power factor is improved. Because of the high power factor after frequency conversion, the equipment occupancy rate can be effectively reduced. At the same time, the soft start function reduces the power grid. Impact, while extending the life of the motor.