Analysis of the Function and Characteristics of Medical Inverter Power Supply

As we all know, power supply is very important for medical institutions, so we often see that medical institutions have strict requirements for power supply. Whether a medical device can play its maximum performance in the hospital is directly related to the technical performance of the machine itself, but also has an extremely important relationship with the quality of the power supply. The quality of the power supply will directly affect the operating stability and reliability of the medical equipment, and even lead to major medical equipment accidents and huge economic losses.

At present, most domestic medical equipment is powered by 220V mains electricity. Due to the power supply requirements of various types of medical equipment, the most commonly used is the centralized power supply structure. That is, a centralized power converter generates the required output voltage of various voltage levels. Due to its low cost, high efficiency, adjustable output voltage, low output noise, fast dynamic response, etc., it is very suitable for medical equipment and is currently the most commonly used power supply method for medical equipment. The following issues need to be considered when determining the power supply solution for medical equipment.

Safety and isolation are major differences between ordinary commercial power supplies and medical power supplies. Usually, except for some experimental analysis instruments, most medical equipment is installed near beds or operating tables, close to people and operators, and the outer shell is often touched. There are various strong and weak current components inside medical equipment. If there is a problem with the isolation between strong and weak currents or the insulation of the outer shell material, it will be very dangerous. In terms of safety testing, general medical equipment power supplies must obtain safety certifications such as UL60601-1, C-UL, and EN60601-1. The input and output terminals must have an isolation voltage of more than 4,000V, and the ground leakage current must be low, meeting the safety creepage distance requirements. Double insulation is required for the strong current part, especially the part that may come into contact with the device shell, and the insulation design must be strengthened.

Electromagnetic compatibility and electromagnetic interference resistance

To select or build a good power supply system for medical equipment, attention must be paid to improving the electromagnetic compatibility and anti-electromagnetic interference capabilities of the power supply. The following aspects should be considered: Design. The design and layout of the PCB. Generally, the power supply contains some high-frequency signals. Any printed line on the PCB can act as an antenna. The length and width of the printed line will affect its impedance and inductance, thereby affecting the frequency response. Even if the printed line of the DC signal passes through the adjacent printed line, it will couple to the RF signal and cause circuit problems. Therefore, medical power supplies must choose products from big brands and companies with strong R&D capabilities. These products can guarantee good quality in design and production processes.

Shielding. In order to suppress the radiation generated by the switching power supply and eliminate the impact of electromagnetic interference on other electronic equipment in the medical device, the best way is to shield the magnetic field of the power supply, and then connect the entire shielding cover to the case or ground of the medical device. This is a way to get twice the result with half the effort.

Certification. At present, general medical equipment power supplies need to undergo electromagnetic compatibility and electromagnetic interference resistance tests such as FCC-B, CISPR22-B, EN55011550226120461000, etc. Selecting products that have completed these tests can not only ensure that there is no electromagnetic impact on other electronic components in the equipment, but also reduce the medical equipment R&D cycle and the inspection time before it is put on the market.

Size and high power density. In addition to the development of multi-function, high detection and adjustment accuracy, medical equipment is also developing in a smaller size and easy to carry. This requires that the power supply of medical equipment must have higher power output under the condition of smaller board area.

Special applications. Most of the centralized power supply products on the market currently have standard outputs. Even if some power supply products can adjust the output through external circuits, the adjustment range is not large, and there are also problems with stability. What should we do if we encounter low voltage, high current or extremely high DC voltage? Of course, we can use customization, but the price is quite high. Can customers accept it?

Price. Nowadays, the price of medical equipment has gradually become transparent due to fierce competition, especially some small medical equipment for home use, which has become very popular and accessible to the general public. Therefore, this requires that the power supply, an important component of medical equipment, must have a competitive price.