Hf machine: Using high frequency switching technology, frequency of hf machine is generally above 20kHz. But the endurance capacity of hf machine is poor in harsh electrical and environmental conditions. It is suitable for the environment with stable power grid, less dust and suitable temperature/humidity. The development direction of UPS is high-frequency, miniaturization, intelligence and greening. Miniaturization can save investment, improve efficiency and save space. The premise of miniaturization is high-frequency, and only high-frequency can realize miniaturization. The first goal of miniaturization is to eliminate the input/output isolation transformer. In the past, due to the reasons of technical, device and material, USP was added the input/output isolation transformer, which made the product bulky, expensive and of poor performance, high energy consumption. Later, due to the advent of new devices, the new scheme was first introduced by IPM in the United States and it successfully eliminated the input isolation transformer in 1980. In recent years, due to the further development and maturity of technology, the half-bridge inverter transformation scheme has been put forward, and the output isolating transformer is removed successfully, which greatly improves the performance of UPS. This is what people call a hf machine. It further enables UPS to reduce volume, improve performance, reduce weight, improve efficiency, reduce cost and improve reliability. So most of the internationally renowned companies have abandoned the production of UPS with output isolation transformer.
2.The advantages of hf machine
The advantages of hf machine: it is of small size, light weight, high operation efficiency (low operation cost), and low noise. It is suitable for office space. It is of high cost performance (low price under the same power). It has little effect on space and environment. According to different requirements, installation environment, load conditions, etc, users can weigh their options.
The hf machine has no isolating transformer. Its output neutral line has high-frequency current, mainly from the harmonic of the municipal power grid, UPS rectifier and high-frequency inverter ripple current, load harmonic *, etc. The voltage is not only high but also difficult to eliminate. The output voltage of power frequency machine is low, and there is no high frequency component, which is more important for the communication security of computer network.