0 Preface With the highly developed medical electronics technology, the type of medical devices more and more, medical equipment and modern medical diagnosis, treatment closer ties, are inseparable from any medical device security and stability of power supply. According to relevant statistics, power failures account for more than 60% of machine failures, and most of them are switching power supplies. Therefore, it is very important for the instrument maintenance personnel to master the basic composition, working principle and troubleshooting experience of the switching power supply. 1 Introduction to switching power supply 1.1 Switching power supply Most switching power supplies are mainly composed of electromagnetic interference filters, anti-surge control circuits, rectifier filter circuits, switching transformers, switching components, pulse width modulation components and other components. The typical structure of the switching power supply includes a series switching power supply structure, a parallel switching power supply structure, a forward switching power supply structure, a flyback switching power supply structure, a half bridge switching power supply structure, and a full bridge switching power supply structure. Since the flyback switching power supply is one of the most basic structures and is widely used in the field of medical equipment, it will be highlighted below. 1.2 flyback switching power supply The working principle of the flyback switching power supply can be summarized as follows: when the power tube is turned on, the transformer only stores energy and does not provide energy to the secondary; after the shutdown, the transformer releases the energy to the secondary, and the circuit topology is as shown in FIG. It has the advantages of simple circuit (saving a large inductance) and not afraid of load short circuit. However, since the iron core is in a unidirectional magnetization state, in order to prevent magnetic saturation, a large iron core is required, which means large volume, so it is widely used in 100- 150W medium and small power switching power supply. 1.3 Power section of the Mindray PM9000 monitor The overall functional block diagram of the power supply part of a monitor is shown in Figure 2. The functions and relationships of the power modules are as follows. Rhodium powder Rh≥99.95% Properties: silver-white metal, extremely hard, wear-resistant, also has considerable ductility Application: It can be used as raw material for electrical instrumentation, chemical industry and manufacture of precision alloys. Rhodium powder is based on the widespread use of ruthenium in the industrial industry. Since rhodium is a rare metal required by the industry, the industry price is slightly higher than that of general non-ferrous metals. Rhodium, one of the rare elements, has various uses. Rhodium can be used to make hydrogenation catalysts, thermocouples, platinum-rhodium alloys, etc. It is also often plated on searchlights and reflectors, and is also used as a polishing agent for gemstones. and electrical contact parts. precious metal XI AN RHINE BIOLOGICAL TECHNOLOGY CO.,LTD , https://www.rhinebiotech.com
Talking about the maintenance of switching power supply for medical equipment