Functions and characteristics of medical inverter power supply
At present, most medical equipment in China is powered by 220V mains electricity. Due to the power supply requirements of various types of medical equipment, the most commonly used structure currently is centralized power supply. That is, a centralized power converter generates output voltages of various voltage levels required. Due to its low cost, high efficiency, adjustable output voltage, low output noise, and fast dynamic response, it is very suitable for use in medical equipment and is currently the most commonly used power supply method for medical equipment. The determination of the power supply scheme for medical equipment needs to consider the following issues.
Safety and isolation are significant differences between ordinary commercial power sources and medical power sources. Usually, except for some experimental analysis instruments, medical equipment is mostly installed near hospital beds or operating tables, close to people and operators, and the casing is often touched. There are various strong and weak electrical components inside medical equipment. If there is a problem with the isolation between strong and weak electrical components or the insulation of the casing material, it can be very dangerous** In terms of testing, general medical equipment power supplies must obtain certifications such as UL60601-1, C-UL, EN60601-1, etc. The input and output terminals must have an isolation voltage of 4000V or above, and the ground leakage current must be low, meeting the requirements of safety regulations for creepage distance. For the strong electrical parts, double insulation is required, especially for the parts that may come into contact with the equipment casing, insulation design should be strengthened.
Electromagnetic compatibility and anti-interference ability
To choose or build a good power supply system for medical equipment, it is necessary to pay attention to improving the electromagnetic compatibility and anti-interference ability of the power supply. The main aspects to consider are: design. The design and layout of PCBs usually contain high-frequency signals in power supplies. Any printed line on the PCB can act as an antenna, and the length and width of the printed line will affect its impedance and inductance, thereby affecting the frequency response. Even printed lines that transmit DC signals can couple to RF signals from adjacent printed lines and cause circuit problems. So medical power supplies must choose products from companies with strong research and development capabilities, which can ensure good quality in both design and production processes.
shield
A good way to suppress the radiation generated by switch mode power supplies and eliminate the impact of electromagnetic interference on other electronic devices inside medical equipment is to shield the magnetic field of the power supply, and then connect the entire shielding cover to the casing or ground of the medical equipment. This is a twice the result with half the effort.
