Circuit capable of automatically adapting to alternating current 110V and 220V power supply input

Abstract

The invention relates to a circuit capable of automatically adapting to alternating current 110V and 220V power supply input. The circuit comprises a soft start control module and a voltage identification module, the input end of the soft start control module is connected with commercial power, and the output end is connected with the input end of the voltage identification module; the output end of the voltage identification module is connected to a primary coil of an external isolation transformer; the soft start control module comprises a piezoresistor and a time delay relay; the voltage identification module comprises a voltage dividing assembly and a determination assembly. According to the circuit capable of automatically adapting to alternating current 110V and 220V power supply input, the problem that equipment is damaged or tripped due to impact current when the equipment is just powered on can be effectively solved, and the safety of the equipment is improved; moreover, the device can automatically adapt to the input of ac.110V and ac.220V power supplies, improves the compatibility of the device with voltage, and can solve the surge problem generated by an isolation transformer.

Description

Technical Field

[0001] The invention belongs to the technical field of medical devices, and in particular relates to a circuit which automatically adapts to AC 110V and 220V power inputs. Background Art

[0002] In order to ensure the safe use of equipment and suppress the high-frequency noise from entering the control circuit, many medical equipment often use isolation transformers when designing the power supply circuit. The main function of the isolation transformer is to completely insulate the primary and secondary sides of the transformer, so that the electrical circuit on the equipment side is completely isolated from the main power supply circuit of the mains. At this time, the isolation transformer suspends the secondary side to the ground, and the system's capacitive current to the ground is too small to cause harm to people, making the electrical use of the equipment safer. Furthermore, because the isolation transformer core has the characteristics of large high-frequency loss, it can suppress the high-frequency noise from entering the main control circuit on the equipment side.

[0003] The voltage standards for city electricity vary from country to country. The voltage standards for China and continental Europe are both 220V, 50Hz; the voltage standard for North America is 120V, 60Hz, which is specified by the United States and Canada and widely adopted by these two countries; the voltage standard for Japan is 100V, 50Hz or 60Hz; the voltage standard for South Korea is 220V, 60Hz; and the voltage standard for India is 230V, 50Hz.

[0004] Based on the above reasons, the following problems need to be solved when designing the equipment: 1. Due to the use of isolation transformers, the starting current is often very high, even 6-10 times the operating current. Therefore, the starting current when the equipment is just powered on can easily cause damage to the equipment or affect the grid load and cause tripping, affecting the normal operation of other equipment. Therefore, it is necessary to solve the problem of soft starting of the equipment.

[0005] 2. Due to various considerations such as cost, not all electrical components integrated into the designed medical device system can support 100-240V / AC wide voltage input. Many electrical components can only support power supply in the 220V / AC voltage range, resulting in the need for the equipment to specifically solve the power supply problem in the 110V / AC voltage range. Summary of the invention

[0006] The technical problem to be solved by the present invention is: to overcome the disadvantages of the above-mentioned technology and to provide a circuit which can automatically adapt to AC.110V and AC.220V power input and has a soft start function.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is: a circuit that automatically adapts to AC 110V and 220V power input, comprising: a soft start control module and a voltage identification module; the input end of the soft start control module is connected to the mains, and the output end is connected to the input end of the voltage identification module; the output end of the voltage identification module is connected to the primary coil of an external isolation transformer; the soft start control module includes a varistor and a time delay relay; the varistor is connected in series between the input end and the output end of the soft start control module; the contact group of the time delay relay is also connected in series to the soft start control module. between the input and output ends of the starting control module; the coil of the delay relay is powered by the mains electricity connected to the input end of the soft starting control module; the voltage identification module includes a voltage dividing component and a determination component; the voltage dividing component divides the input voltage and sends it to the determination component; the determination component also inputs a standard voltage; the determination component controls a switching relay; the common contact of the switching relay is connected to the output end of the soft starting control module; the two output contacts of the switching relay are respectively connected to the 110V connector and the 220V connector in the primary coil of the external isolation transformer.

[0008] A further improvement of the above scheme is that the normally open contact of the switching relay is connected to the 110V connector in the primary coil of the external isolation transformer, and the normally closed contact is connected to the 220V connector in the primary coil of the external isolation transformer.

[0009] A further improvement of the above scheme is that: the voltage identification module includes a rectifier component, the input of the rectifier component is connected to the output of the soft start control module, and is sent to the voltage divider component after rectification.

[0010] A further improvement of the above scheme is that the voltage divider component is two groups of voltage divider resistors, the two groups of voltage divider resistors are connected in series, the middle node is used as the output, and the two ends are respectively connected to the two levels of the output end of the rectifier component.

[0011] The circuit automatically adapting to AC 110V and 220V power input provided by the present invention can effectively solve the problem of equipment damage or tripping due to impact current when the equipment is just powered on, thereby improving the safety of the equipment; and can automatically adapt to the input of AC.110V and AC.220V power supply, thereby improving the compatibility of the equipment with voltage, and in addition can solve the surge problem generated by the isolation transformer. The present invention uses a relatively simple and mature circuit solution, and is easy to be applied to various devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will be further described below in conjunction with the accompanying drawings.

[0013] Figure 1 It is a structural schematic diagram of a preferred embodiment of the present invention.

[0014] Figure 2 yes Figure 1 Circuit diagram of the soft start control module in.

[0015] Figure 3 yes Figure 1 Circuit diagram of the voltage identification module in.

[0016] Figure 4 It is a schematic diagram of the isolation transformer structure. DETAILED DESCRIPTION

[0017] The circuit of this embodiment automatically adapts to AC 110V and 220V power input, such as Figure 1 As shown, it includes: a soft start control module and a voltage identification module; the input end of the soft start control module is connected to the mains, and the output end is connected to the input end of the voltage identification module; the output end of the voltage identification module is connected to the primary coil of the external isolation transformer.

[0018] like Figure 2 As shown, the soft start control module includes a varistor and a delay relay K2; the varistor is connected in series between the input and output ends of the soft start control module; the contact group of the delay relay K2 is also connected in series between the input and output ends of the soft start control module; in this embodiment, a total of 8 varistors RT1 to RT8 are used to form an array, so that the resistance of the varistor array is smaller and the power provided is higher. After the mains power supply is input, it is also connected to the rectifier U1 through the fuse F1 and the resistor R24; the rectifier U1 and its subsequent circuits rectify the input AC and stabilize the voltage to 24V DC, which is supplied to the delay relay K2 and other parts that require DC power supply. At the moment when the device is started and powered on, a large surge current is generated due to the presence of the isolation transformer. In this embodiment, it is limited by the varistor. After a period of delay, the device works stably, the delay relay K2 is attracted, and the device is stably powered by the delay relay K2.

[0019] like Figure 3As shown, the voltage identification module includes a voltage divider component and a determination component. After the mains power supply is input, it is divided by resistor R1 and capacitor CX1, and then input to the voltage divider component; after being rectified into DC by U3 in the voltage divider component, it is filtered by capacitor C4, and then divided by resistors R13 to R20, a total of 8 resistors, and sent to the determination component; the determination component is an operational amplifier U4A, and the voltage dividing point of resistor R20 is input to the inverting input terminal of the operational amplifier U4A, and the non-inverting input terminal of the operational amplifier U4A is connected to the standard voltage. The standard voltage adopts the DC 24V in the soft start control module, which is obtained by dividing the voltage by resistors R21 and R22. The output end of the operational amplifier U4A drives a switching relay K1 through the subsequent circuit. In this way, the switching relay K1 is activated or not according to the size of the input power supply. When the input is AC 220V, the inverting input terminal of the operational amplifier U4A is higher than the non-inverting input terminal, and the switching relay K1 does not operate. When the input is AC 110V, the inverting input terminal of the operational amplifier U4A is lower than the non-inverting input terminal, and the switching relay K1 operates.

[0020] The common contact of the switching relay K1 is connected to the output end of the soft start control module. The normally open contact of the switching relay K1 is connected to the 110V connector in the primary coil of the external isolation transformer, and the normally closed contact is connected to the 220V connector in the primary coil of the external isolation transformer. Thus, a single fault protection circuit is formed.

[0021] The single fault protection circuit is mainly used to avoid the risk of the switching relay K1 failing to switch to the correct position due to incorrect identification of the power supply voltage caused by the occurrence of a single fault. Figure 4 As shown, the isolation transformer adopts a center tap mode, and the ac.110V power supply or ac.220V power supply is connected to the corresponding lead wire of the primary input end of the isolation transformer. The secondary output end of the isolation transformer can output a stable ac.220V power supply to the internal load of the whole machine; since the ac.110V lead wire of the primary input end of the isolation transformer, if the ac.220V voltage is mistakenly supplied, it will cause damage to the rear-end load circuit of the whole machine. Therefore, when the single fault protection circuit recognizes that the power supply is ac.220V voltage, the switching relay K1 is in the disconnected state, and the ac.110V power supply path is cut off to achieve the purpose of single fault state protection.

[0022] The present invention is not limited to the above embodiments. Any technical solution formed by equivalent replacement falls within the protection scope required by the present invention.

Claims

1. A circuit that automatically adapts to AC 110V and 220V power input, characterized in that: include: A soft start control module and a voltage identification module; the input end of the soft start control module is connected to the mains, and the output end is connected to the input end of the voltage identification module; the output end of the voltage identification module is connected to the primary coil of an external isolation transformer; the soft start control module includes a varistor and a time delay relay; the varistor is connected in series between the input end and the output end of the soft start control module; the contact group of the time delay relay is also connected in series between the input end and the output end of the soft start control module; the coil of the time delay relay is powered by the mains connected to the input end of the soft start control module; the voltage identification module includes a voltage dividing component and a determination component; the voltage dividing component divides the input voltage and then sends it to the determination component; the determination component is also input with a standard voltage; the determination component controls a switching relay; the common contact of the switching relay is connected to the output end of the soft start control module; the two output contacts of the switching relay are respectively connected to the 110V connector and the 220V connector in the primary coil of the external isolation transformer.

2. The circuit for automatically adapting to AC 110V and 220V power input according to claim 1, characterized in that: The normally open contact of the switching relay is connected to the 110V connector in the primary coil of the external isolation transformer, and the normally closed contact is connected to the 220V connector in the primary coil of the external isolation transformer.

3. The circuit for automatically adapting to AC 110V and 220V power input according to claim 2, characterized in that: The voltage identification module includes a rectifier component, the input of which is connected to the output of the soft start control module and is sent to the voltage divider component after rectification.

4. The circuit for automatically adapting to AC 110V and 220V power input according to claim 3, characterized in that: The voltage divider component is two groups of voltage divider resistors, which are connected in series, with the middle node serving as the output and the two ends respectively connected to the two levels of the output end of the rectifier component.

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