Automatic switching control circuit for different levels of commercial power input

Abstract

The utility model discloses an automatic switching control circuit for different levels of commercial power input. The automatic switching control circuit comprises a main control circuit and a transformer, the main control circuit comprises a mains supply input socket J1, a 220V voltage output socket and a 110V voltage output socket; commercial power of different grades is input from the commercial power input socket J1 and is switched by the main control circuit, and 220V voltage or 110V voltage is output to the transformer. The main control circuit comprises a relay, a relay driving circuit, a reference voltage forming circuit, a voltage sampling circuit, a voltage comparator and a voltage stabilizing filter circuit; the main control circuit not only can realize automatic switching of different levels of commercial power input so as to ensure stable operation of electric appliances, but also can reduce the risk of misoperation and improve the user experience. Moreover, the circuit structure is simple and reliable, and the fault-tolerant capability is strong. In addition, the circuit provided by the utility model is stable, and the autotransformer cannot be damaged due to the damage of components.

Description

Technical Field

[0001] The utility model belongs to the technical field of power supply circuits, and in particular relates to automatic switching control circuits for different levels of mains input. Background Art

[0002] At present, the design of the conversion circuit of two different levels of mains using autotransformers on the market plays a vital role in the popularization of electrical appliances and the promotion of the global market. However, the existing conversion circuits configured for two different levels of mains using autotransformers generally have the following disadvantages:

[0003] 1) Limited voltage adaptability: Most conversion circuits are only designed to be suitable for power grids with specific voltages, such as 220V or 110V; and the conversion circuits in the prior art can generally only achieve a single voltage conversion function, for example: when the input is 220V and the electrical appliance is adapted to 110V, the user needs to manually switch the 220V to 110V mode; and when the input is 110V and the electrical appliance is adapted to 220V, the user needs to manually switch the 110V to 220V mode. If the input is 220V and the electrical appliance is adapted to 110V, and the user does not switch the corresponding conversion mode in time, it will cause damage to the electrical appliance; therefore, the prior art has certain risks caused by operational errors, and also brings inconvenience to users, and may even cause personal safety problems due to connecting to the wrong mains power.

[0004] 2) Voltage switching is complex and costly: Although a few conversion circuits can be used for both 220V and 110V power grids, these conversion circuits usually use a complex switching circuit structure, which not only increases the manufacturing cost but also reduces the reliability and stability of the conversion circuit. In addition, the complex circuit structure may also cause users to encounter operational difficulties during use, further reducing the user experience.

[0005] Therefore, there is an urgent need for an automatic switching control circuit for different levels of mains input to solve the above problems. Summary of the invention

[0006] In view of the problems in the related technology, the utility model proposes an automatic switching control circuit for different levels of AC power input to overcome the above-mentioned technical problems existing in the existing related technology. The main control circuit described in the utility model includes a relay, a relay driving circuit, a reference voltage forming circuit, a voltage sampling circuit and a voltage comparator; after different levels of AC power are input from the AC power input socket J1, they can be switched through the main control circuit and output 220V voltage or 110V voltage to the transformer; in this way, it can realize automatic switching of different levels of AC power input and ensure the stable operation of electrical appliances, which is highly practical.

[0007] The technical solution of the utility model is implemented as follows: different levels of mains input automatic switching control circuit, including a main control circuit and a transformer, the main control circuit includes a mains input socket J1, a 220V voltage output socket and a 110V voltage output socket; wherein the main control circuit is connected to the live wires of different levels of mains through the mains input socket J1; the transformer is connected to the neutral wires of different levels of mains; the 220V voltage output socket and the 110V voltage output socket are respectively connected to the transformer; different levels of mains are input from the mains input socket J1, and are switched by the main control circuit to output 220V voltage or 110V voltage to the transformer;

[0008] The main control circuit includes a relay, and the relay is connected to the main power input socket J1, the 220V voltage output socket and the 110V voltage output socket respectively; the main control circuit also includes a relay drive circuit, a reference voltage forming circuit, a voltage sampling circuit and a voltage comparator; the voltage comparator includes a first port, a second port and a third port; the relay is connected to the first port through the relay drive circuit; the reference voltage forming circuit is connected to the third port, and the voltage sampling circuit is connected to the second port; the voltage sampling circuit is connected to the relay drive circuit;

[0009] The reference voltage forming circuit is used to obtain a reference voltage;

[0010] The voltage sampling circuit is used to obtain a sampled voltage;

[0011] The voltage comparator controls the first port of the voltage comparator to output a high level or low level voltage by comparing the reference voltage with the sampling voltage;

[0012] The relay driving circuit controls the closing or releasing of the relay according to the output voltage of the first port of the voltage comparator.

[0013] Furthermore, the relay includes a common pole, a normally open contact NO and a normally closed contact NC; the common pole is connected to the AC input socket J1, the normally open contact NO is connected to the 110V voltage output socket, and the normally closed contact NC is connected to the 220V voltage output socket.

[0014] Furthermore, it also includes connector J2, connector J4, connector J5 and connector J7; the main control circuit is connected to the same neutral line with the transformer through the connector J2; the transformer is connected to the 220V voltage output socket through the connector J4, and the transformer is connected to the 110V voltage output socket through the connector J5; the main control circuit is connected to the transformer through the connector J7, and the transformer inputs 12V power to the main control circuit through the connector J7.

[0015] Furthermore, the main control circuit further includes a voltage stabilizing filter circuit, and the voltage stabilizing filter circuit is connected to the voltage sampling circuit;

[0016] The voltage stabilizing filter circuit includes a power rectifier bridge stack DB1; the power rectifier bridge stack DB1 includes a first interface, a second interface, a third interface and a fourth interface, the first interface and the third interface are both voltage input terminals, the second interface and the fourth interface are both voltage output terminals; the first interface is connected to the connector J7, and the third interface is connected to the connector J2; the second interface and the fourth interface are simultaneously connected to an electrolytic capacitor C2 and a ceramic capacitor CC2, and the electrolytic capacitor C2 and the ceramic capacitor CC2 are connected in parallel;

[0017] The ceramic capacitor CC2 is connected to the power input terminal ACK of the voltage sampling circuit;

[0018] The 12V power supply is input from the first interface, and is rectified and filtered by the power rectifier bridge DB1, the electrolytic capacitor C2, and the ceramic capacitor CC2 in sequence to output direct current; the direct current is output in two ways, one way is output to the positive electrode of the electrolytic capacitor C2, and the other way is output to the power input terminal ACK of the reference voltage forming circuit;

[0019] Preferably, the voltage range of the direct current is 15-17V.

[0020] Furthermore, the voltage stabilizing filter circuit further includes a voltage stabilizing block VR1, the input terminal Vin of the voltage stabilizing block VR1 is connected to the positive electrode of the electrolytic capacitor C2; the output terminal Vout of the voltage stabilizing block VR1 is connected to the filter capacitor C1 and the filter capacitor CC4 in sequence; the filter capacitor C1 is connected in parallel with the filter capacitor CC4;

[0021] The DC power is input from the input terminal Vin of the voltage stabilizing block VR1, and is filtered by the filter capacitor C1 and the filter capacitor CC4 in sequence to output a +5V regulated power supply;

[0022] Preferably, the voltage regulator block VR1 is a three-terminal voltage regulator tube 78105.

[0023] Further, the voltage sampling circuit includes a voltage divider network unit, which includes a resistor R5, a resistor R9, a resistor R12 and a transistor Q2; the resistor R5, the resistor R9 and the collector of the transistor Q2 are connected in sequence; one end of the resistor R12 is connected between the resistor R5 and the resistor R9, and the other end of the resistor R12 is connected to the emitter of the transistor Q2 and grounded; the base of the transistor Q2 is connected to the power input terminal SW of the relay drive circuit;

[0024] The DC power input from the power input terminal ACK of the voltage sampling circuit obtains a DC sampling value proportional to the input mains voltage after passing through the voltage dividing network unit. When the mains voltage is 220V, the corresponding DC sampling value is 2.4V.

[0025] Furthermore, the voltage sampling circuit further includes a resistor R1, a diode D2, a resistor R7 and a capacitor CC1; the resistor R5, the resistor R1, the resistor R7 and the second port of the voltage comparator are connected in sequence; the diode D2 is connected in parallel with the resistor R1, and the diode D2 is connected to the capacitor CC1 and grounded;

[0026] The DC sampling value is quickly charged to the capacitor CC1 through the diode D2, and the resistor R1 serves as the discharge resistor of the capacitor CC1; the resistor R1 and the diode D2 realize the functions of fast charging and slow discharging of the capacitor CC1; the voltage on the capacitor CC1 is connected to the second port of the voltage comparator through the resistor R7.

[0027] Further, the reference voltage forming circuit includes a resistor R2, a resistor R3, a resistor R4, a resistor R6 and a capacitor CC3; the resistor R3, the resistor R6, the resistor R2 and the third port of the voltage comparator are connected in sequence; one end of the resistor R4 is connected between the resistor R3 and the resistor R6, and the other end of the resistor R4 is grounded; one end of the capacitor CC3 is connected between the resistor R6 and the resistor R2, and the other end of the capacitor CC3 is grounded; a +5V regulated power supply flows in from the resistor R3, and outputs the reference voltage to the voltage comparator after passing through the reference voltage forming circuit;

[0028] The reference voltage is set at 1.5V; the capacitor CC3 is relatively large, and the resistance of the resistor R6 is in the megaohm range, so the reference voltage formation time of the capacitor CC3 is faster than the establishment time of the sampling voltage on the capacitor CC1.

[0029] Further, the relay drive circuit includes a resistor R8, a resistor R10 and a transistor Q1; the base of the transistor Q1, the resistor R10 and the first port of the voltage comparator are connected in sequence; one end of the resistor R8 is connected to the base of the transistor Q1, and the other end of the resistor R8 is connected to the emitter of the transistor Q1 and grounded; the collector of the transistor Q1 is connected to one end of the control coil of the relay, and the other end of the control coil of the relay is connected to a +5V regulated power supply;

[0030] A diode D1 is also included, and the diode D1 is connected in parallel with two ends of the control coil of the relay.

[0031] Furthermore, the different levels of mains electricity include 220V mains electricity and 110V mains electricity; the transformer is an autotransformer;

[0032] The voltage comparator further includes a fourth port and a fifth port; the fifth port is a power input terminal of the voltage comparator and is connected to a +5V regulated power supply; the fourth port is a power output terminal of the voltage comparator and is grounded;

[0033] The first port is the output terminal of the voltage comparator, the second port is the negative phase input terminal, and the third port is the positive phase input terminal; the voltage comparator is an operational amplifier IC5A.

[0034] Beneficial effects of the utility model:

[0035] The utility model discloses a different level of mains input automatic switching control circuit, including a main control circuit and a transformer; the main control circuit includes a mains input socket J1, a 220V voltage output socket and a 110V voltage output socket; different levels of mains are input from the mains input socket J1, and are switched by the main control circuit to output 220V voltage or 110V voltage to the transformer; the main control circuit includes a relay, a relay drive circuit, a reference voltage forming circuit, a voltage sampling circuit and a voltage comparator; the voltage comparator includes a first port, a second port and a third port; the relay is connected to the first port of the voltage comparator through a relay drive circuit; the reference voltage forming circuit is connected to the third port, and the voltage sampling circuit is connected to the second port; the voltage sampling circuit is connected to the relay drive circuit; the main control circuit can not only realize automatic switching of different levels of mains input to ensure the stable operation of electrical appliances, but also reduce the risk of operating errors and improve user experience. Moreover, the circuit structure of the utility model is simple and reliable, and has strong fault tolerance; in addition, the circuit of the utility model is stable, and the autotransformer will not be damaged due to damage to components. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a working principle diagram of the automatic switching control circuit of different levels of mains input of the utility model;

[0037] Figure 2 It is a structural schematic diagram of the automatic switching control circuit of different levels of mains input of the utility model;

[0038] Figure 3 The utility model is a circuit diagram of an automatic switching control circuit for different levels of mains input. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0041] like Figure 1-Figure 3 As shown, this embodiment provides an automatic switching control circuit for mains input of different levels, including a main control circuit and a transformer, wherein the main control circuit includes a mains input socket J1, a 220V voltage output socket and a 110V voltage output socket; wherein the main control circuit is connected to live wires of mains of different levels through the mains input socket J1; the transformer is connected to neutral wires of mains of different levels; the 220V voltage output socket and the 110V voltage output socket are respectively connected to the transformer; mains of different levels are input from the mains input socket J1, and are switched by the main control circuit to output 220V voltage or 110V voltage to the transformer;

[0042] The main control circuit includes a relay, and the relay is connected to the main power input socket J1, the 220V voltage output socket and the 110V voltage output socket respectively; the main control circuit also includes a relay drive circuit, a reference voltage forming circuit, a voltage sampling circuit and a voltage comparator; the voltage comparator includes a first port, a second port and a third port; the relay is connected to the first port of the voltage comparator through the relay drive circuit; the reference voltage forming circuit is connected to the third port, and the voltage sampling circuit is connected to the second port; the voltage sampling circuit is connected to the relay drive circuit;

[0043] The reference voltage forming circuit is used to obtain a reference voltage;

[0044] The voltage sampling circuit is used to obtain a sampled voltage;

[0045] The voltage comparator controls the first port of the voltage comparator to output a high level or low level voltage by comparing the reference voltage with the sampling voltage;

[0046] The relay driving circuit controls the closing or releasing of the relay according to the output voltage of the first port of the voltage comparator;

[0047] In this embodiment, by setting the relay, relay driving circuit, reference voltage forming circuit, voltage sampling circuit and voltage comparator, different levels of AC power can be automatically switched through the main control circuit after being input from the AC power input socket J1, and 220V voltage or 110V voltage can be output to the transformer; this can not only realize automatic switching of different levels of AC power input, but also ensure the stable operation of electrical appliances, which is highly practical and avoids the risks and inconveniences brought by manual switching circuits in the prior art.

[0048] Specifically, the relay includes a common pole, a normally open contact NO and a normally closed contact NC; the common pole is connected to the mains input socket J1, the normally open contact NO is connected to the 110V voltage output socket, and the normally closed contact NC is connected to the 220V voltage output socket;

[0049] In this embodiment, if Figure 3 As shown, when the mains input socket J1 inputs 220V voltage, the relay is released, the common pole is connected to the normally closed contact NC, and the 220V voltage is connected to the 220V end of the transformer through the normally closed contact NC;

[0050] When the mains input socket J1 inputs a 110V voltage, the relay is energized, the common pole is connected to the normally open contact NO, and the 110V voltage is connected to the 110V terminal of the transformer through the normally open contact NO.

[0051] Specifically, it also includes connector J2, connector J4, connector J5 and connector J7; the main control circuit is connected to the same neutral line with the transformer through the connector J2; the transformer is connected to the 220V voltage output socket through the connector J4, and the transformer is connected to the 110V voltage output socket through the connector J5; the main control circuit is connected to the transformer through the connector J7, and the transformer inputs 12V power to the main control circuit through the connector J7.

[0052] Specifically, the main control circuit further includes a voltage stabilizing filter circuit, and the voltage stabilizing filter circuit is connected to the voltage sampling circuit;

[0053] The voltage stabilizing filter circuit includes a power rectifier bridge stack DB1; the power rectifier bridge stack DB1 includes a first interface, a second interface, a third interface and a fourth interface, the first interface and the third interface are both voltage input terminals, the second interface and the fourth interface are both voltage output terminals; the first interface is connected to the connector J7, and the third interface is connected to the connector J2; the second interface and the fourth interface are simultaneously connected to an electrolytic capacitor C2 and a ceramic capacitor CC2, and the electrolytic capacitor C2 and the ceramic capacitor CC2 are connected in parallel;

[0054] The ceramic capacitor CC2 is connected to the power input terminal ACK of the reference voltage forming circuit;

[0055] The 12V power supply is input from the first interface, and is rectified and filtered by the power rectifier bridge DB1, the electrolytic capacitor C2, and the ceramic capacitor CC2 in sequence to output direct current; the direct current is output in two ways, one way is output to the positive electrode of the electrolytic capacitor C2, and the other way is output to the power input terminal ACK of the voltage sampling circuit;

[0056] Specifically, the voltage range of the direct current is 15-17V.

[0057] Specifically, the voltage stabilizing filter circuit further includes a voltage stabilizing block VR1, the input terminal Vin of the voltage stabilizing block VR1 is connected to the positive electrode of the electrolytic capacitor C2; the output terminal Vout of the voltage stabilizing block VR1 is connected to the filter capacitor C1 and the filter capacitor CC4 in sequence; the filter capacitor C1 is connected in parallel with the filter capacitor CC4;

[0058] The DC power is input from the input terminal Vin of the voltage stabilizing block VR1, and is filtered by the filter capacitor C1 and the filter capacitor CC4 in sequence to output a +5V regulated power supply;

[0059] Specifically, the voltage regulator block VR1 is a three-terminal voltage regulator tube 78105.

[0060] Specifically, the voltage sampling circuit includes a voltage divider network unit, which includes a resistor R5, a resistor R9, a resistor R12 and a transistor Q2; the resistor R5, the resistor R9 and the collector of the transistor Q2 are connected in sequence; one end of the resistor R12 is connected between the resistor R5 and the resistor R9, and the other end of the resistor R12 is connected to the emitter of the transistor Q2 and grounded; the base of the transistor Q2 is connected to the power input terminal SW of the relay drive circuit;

[0061] The DC power input from the power input terminal ACK of the voltage sampling circuit obtains a DC sampling value proportional to the input mains voltage after passing through the voltage dividing network unit. When the mains voltage is 220V, the corresponding DC sampling value is 2.4V.

[0062] Specifically, the voltage sampling circuit further includes a resistor R1, a diode D2, a resistor R7 and a capacitor CC1; the resistor R5, the resistor R1, the resistor R7 and the second port of the voltage comparator are connected in sequence; the diode D2 is connected in parallel with the resistor R1, and the diode D2 is connected to the capacitor CC1 and grounded;

[0063] The DC sampling value is quickly charged to the capacitor CC1 through the diode D2, and the resistor R1 serves as the discharge resistor of the capacitor CC1; the resistor R1 and the diode D2 realize the functions of fast charging and slow discharging of the capacitor CC1; the voltage on the capacitor CC1 is connected to the second port of the voltage comparator through the resistor R7.

[0064] Specifically, the reference voltage forming circuit includes a resistor R2, a resistor R3, a resistor R4, a resistor R6 and a capacitor CC3; the resistor R3, the resistor R6, the resistor R2 and the third port of the voltage comparator are connected in sequence; one end of the resistor R4 is connected between the resistor R3 and the resistor R6, and the other end of the resistor R4 is grounded; one end of the capacitor CC3 is connected between the resistor R6 and the resistor R2, and the other end of the capacitor CC3 is grounded; a +5V regulated power supply flows in from the resistor R3, and outputs the reference voltage to the voltage comparator after passing through the reference voltage forming circuit;

[0065] The reference voltage is set at 1.5V; the capacitor CC3 is relatively large, and the resistance of the resistor R6 is in the megaohm range, so the reference voltage formation time of the capacitor CC3 is slower than the establishment time of the sampling voltage on the capacitor CC1.

[0066] Specifically, the relay drive circuit includes a resistor R8, a resistor R10 and a transistor Q1; the base of the transistor Q1, the resistor R10 and the first port of the voltage comparator are connected in sequence; one end of the resistor R8 is connected to the base of the transistor Q1, and the other end of the resistor R8 is connected to the emitter of the transistor Q1 and grounded; the collector of the transistor Q1 is connected to one end of the control coil of the relay, and the other end of the control coil of the relay is connected to a +5V regulated power supply;

[0067] A diode D1 is also included, and the diode D1 is connected in parallel with two ends of the control coil of the relay.

[0068] Specifically, the different levels of mains electricity include 220V mains electricity and 110V mains electricity; the transformer is an autotransformer;

[0069] The voltage comparator further includes a fourth port and a fifth port; the fifth port is a power input terminal of the voltage comparator and is connected to a +5V regulated power supply; the fourth port is a power output terminal of the voltage comparator and is grounded;

[0070] The first port is the output terminal of the voltage comparator, the second port is the negative phase input terminal, and the third port is the positive phase input terminal; the voltage comparator is an operational amplifier IC5A.

[0071] In this embodiment, if Figure 3 As shown, the working principle of the automatic switching control circuit of different levels of mains input is as follows:

[0072] When 220V mains electricity is input to the common pole of the relay through the mains input socket J1, since the relay is in the released state, the 220V mains electricity is connected to the 220V end of the autotransformer through the normally closed contact NC. At this time, the connector J7 will obtain a 12V AC power supply, and quickly form a 2.4V DC sampling voltage at the 2nd foot of the operational amplifier IC5A through the voltage sampling circuit. The 12V AC power supply will then slowly form a 1.5V reference voltage at the 3rd foot of the operational amplifier IC5A through the voltage stabilizing filter circuit and the reference voltage forming circuit; since the reference voltage is lower than the sampling voltage, the 1st foot of the operational amplifier IC5A outputs a low level, the transistor Q1 is cut off and cannot drive the relay to close, the normally closed contact NC remains on, the 220V mains electricity is accurately added to the 220V end of the autotransformer, and the 220V electrical appliances work normally.

[0073] If the input voltage of the relay drops from 220V to below 130V, the reference voltage remains at 1.5V due to the voltage stabilizing filter circuit, and the voltage obtained by the voltage sampling circuit becomes 2.4V*130 / 220=1.42V. When the capacitor CC1 slowly discharges through the resistor R1 to reduce the sampling voltage to 1.42V, the pin 1 of the operational amplifier IC5A flips to output a high level, the transistor Q1 is turned on to cause the relay to close, and the input 130V voltage is connected to the 110V end of the autotransformer by closing the normally open contact NO. At this time, the 220V end of the autotransformer is used as the output voltage, that is, the input of the mains below 130V is realized, and finally converted to 220V output, thereby realizing the automatic switching of different levels of power input.

[0074] In the above state, if the input voltage of the relay increases to more than 140V, the capacitor CC1 will be quickly charged to 2.4V*140 / 220=1.52V through the diode D1, and the pin 1 of the operational amplifier IC5A will flip again to output a low level, the relay will be released, and the input voltage will be switched to the 220V end of the autotransformer, and the 110V end of the autotransformer will be used as the output voltage; the goal of fast switching is achieved again, and the input exceeding 140V is converted into an output of 110V, ensuring the stable operation of the 110V electrical appliances.

[0075] Compared with the prior art, the automatic switching control circuit for different levels of mains input in this embodiment has the following improvements:

[0076] 1. To prevent malfunction caused by instantaneous voltage drop when 220V voltage is input to the relay, the malfunction is to prevent 220V voltage from being mistakenly connected to 110V electrical appliances; the capacitor CC1 is improved to slow discharge, and at the same time, it is ensured that when 110V voltage is input, the voltage rises to a certain value and quickly switches to the 220V input end, and the circuit ensures the function of fast charging.

[0077] 2. The purpose of slow reference voltage establishment is: when the electrical appliance is powered on from a cold state, no matter what level the input voltage is, the common pole of the relay should be connected to the 220V end of the autotransformer, that is, the relay cannot be closed, and the sampling voltage is established first, and then the reference voltage is established, to ensure that there is no malfunction at the time of power-on; wherein, slow establishment means that this embodiment uses a large resistor R6 of 1 megohm and a large capacitor CC3, which slows down the charging process of the capacitor CC3; the cold state refers to when the electrical appliance has no input power.

[0078] 3. The sampling circuits for the 220V voltage input state and the 110V voltage input state of the electrical appliance are automatically switched, and the sampling ratio of the two states is adjusted to ensure that the sampled voltage reflects the actual input voltage.

[0079] According to the disclosure and teaching of the above description, the technical personnel in the field to which the utility model belongs can also change and modify the above implementation. Therefore, the utility model is not limited to the specific implementation methods disclosed and described above, and some modifications and changes to the utility model should also fall within the scope of protection of the claims of the utility model. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the utility model.

Claims

1. The automatic switching control circuit for different levels of mains input includes a main control circuit and a transformer, characterized in that: The main control circuit includes a mains input socket J1, a 220V voltage output socket and a 110V voltage output socket; wherein the main control circuit is connected to live wires of mains of different levels through the mains input socket J1; the transformer is connected to neutral wires of mains of different levels; the 220V voltage output socket and the 110V voltage output socket are connected to the transformer respectively; mains of different levels are input from the mains input socket J1, and are switched by the main control circuit to output 220V voltage or 110V voltage to the transformer; The main control circuit includes a relay, which is respectively connected to the AC input socket J1, the 220V voltage output socket and the 110V voltage output socket; the main control circuit also includes a relay drive circuit, a reference voltage forming circuit, a voltage sampling circuit and a voltage comparator; the voltage comparator includes a first port, a second port and a third port; the relay is connected to the first port through the relay drive circuit; the reference voltage forming circuit is connected to the third port, and the voltage sampling circuit is connected to the second port; the voltage sampling circuit is connected to the relay drive circuit.

2. The automatic switching control circuit for different levels of mains input according to claim 1, characterized in that: The relay includes a common pole, a normally open contact NO and a normally closed contact NC; the common pole is connected to the mains input socket J1, the normally open contact NO is connected to the 110V voltage output socket, and the normally closed contact NC is connected to the 220V voltage output socket.

3. The automatic switching control circuit for different levels of mains input according to claim 1, characterized in that: It also includes connector J2, connector J4, connector J5 and connector J7; the main control circuit is connected to the same neutral line with the transformer through the connector J2; the transformer is connected to the 220V voltage output socket through the connector J4, and the transformer is connected to the 110V voltage output socket through the connector J5; the main control circuit is connected to the transformer through the connector J7, and the transformer inputs 12V power to the main control circuit through the connector J7.

4. The automatic switching control circuit for different levels of mains input according to claim 3, characterized in that: The main control circuit also includes a voltage stabilizing filter circuit, and the voltage stabilizing filter circuit is connected to the voltage sampling circuit; The voltage stabilizing filter circuit includes a power rectifier bridge stack DB1; the power rectifier bridge stack DB1 includes a first interface, a second interface, a third interface and a fourth interface, the first interface and the third interface are both voltage input terminals, the second interface and the fourth interface are both voltage output terminals; the first interface is connected to the connector J7, and the third interface is connected to the connector J2; the second interface and the fourth interface are simultaneously connected to an electrolytic capacitor C2 and a ceramic capacitor CC2, and the electrolytic capacitor C2 and the ceramic capacitor CC2 are connected in parallel; The ceramic capacitor CC2 is connected to the power input terminal ACK of the reference voltage forming circuit; The 12V power supply is input from the first interface, and is rectified and filtered by the power rectifier bridge DB1, electrolytic capacitor C2, and ceramic capacitor CC2 in sequence to output direct current; the direct current is output in two ways, one way is output to the positive electrode of the electrolytic capacitor C2, and the other way is output to the power input terminal ACK of the voltage sampling circuit.

5. The automatic switching control circuit for different levels of mains input according to claim 4, characterized in that: The voltage stabilizing filter circuit further includes a voltage stabilizing block VR1, the input terminal Vin of the voltage stabilizing block VR1 is connected to the positive electrode of the electrolytic capacitor C2; the output terminal Vout of the voltage stabilizing block VR1 is connected to the filter capacitor C1 and the filter capacitor CC4 in sequence; the filter capacitor C1 is connected in parallel with the filter capacitor CC4; The direct current is input from the input terminal Vin of the voltage stabilizing block VR1, and is filtered by the filter capacitor C1 and the filter capacitor CC4 in sequence to output a +5V regulated power supply.

6. The automatic switching control circuit for different levels of mains input according to claim 1, characterized in that: The voltage sampling circuit includes a voltage dividing network unit, which includes a resistor R5, a resistor R9, a resistor R12 and a transistor Q2; the resistor R5, the resistor R9 and the collector of the transistor Q2 are connected in sequence; one end of the resistor R12 is connected between the resistor R5 and the resistor R9, and the other end of the resistor R12 is connected to the emitter of the transistor Q2 and grounded; the base of the transistor Q2 is connected to the power input terminal SW of the relay drive circuit; The direct current input from the power input terminal ACK of the voltage sampling circuit obtains a direct current sampling value proportional to the input mains voltage after passing through the voltage dividing network unit.

7. The automatic switching control circuit for different levels of mains input according to claim 6, characterized in that: The voltage sampling circuit further includes a resistor R1, a diode D2, a resistor R7 and a capacitor CC1; the resistor R5, the resistor R1, the resistor R7 and the second port of the voltage comparator are connected in sequence; the diode D2 is connected in parallel with the resistor R1, and the diode D2 is connected to the capacitor CC1 and grounded; The DC sampling value is quickly charged to the capacitor CC1 through the diode D2, and the resistor R1 serves as a discharge resistor of the capacitor CC1; the voltage on the capacitor CC1 is connected to the second port of the voltage comparator through the resistor R7.

8. The automatic switching control circuit for different levels of mains input according to claim 1, characterized in that: The reference voltage forming circuit includes a resistor R2, a resistor R3, a resistor R4, a resistor R6 and a capacitor CC3; The resistor R3, the resistor R6, the resistor R2 and the third port of the voltage comparator are connected in sequence; one end of the resistor R4 is connected between the resistor R3 and the resistor R6, and the other end of the resistor R4 is grounded; one end of the capacitor CC3 is connected between the resistor R6 and the resistor R2, and the other end of the capacitor CC3 is grounded; the +5V regulated power supply flows into the resistor R3, and outputs the reference voltage to the voltage comparator after passing through the reference voltage forming circuit.

9. The automatic switching control circuit for different levels of mains input according to claim 1, characterized in that: The relay drive circuit comprises a resistor R8, a resistor R10 and a transistor Q1; the base of the transistor Q1, the resistor R10 and the first port of the voltage comparator are connected in sequence; one end of the resistor R8 is connected to the base of the transistor Q1, and the other end of the resistor R8 is connected to the emitter of the transistor Q1 and grounded; the collector of the transistor Q1 is connected to one end of the control coil of the relay, and the other end of the control coil of the relay is connected to a +5V regulated power supply; A diode D1 is also included, and the diode D1 is connected in parallel with two ends of the control coil of the relay.

10. The automatic switching control circuit for different levels of mains input according to claim 1, characterized in that: The different levels of mains electricity include 220V mains electricity and 110V mains electricity; the transformer is an autotransformer; The voltage comparator further includes a fourth port and a fifth port; the fifth port is a power input terminal of the voltage comparator and is connected to a +5V regulated power supply; the fourth port is a power output terminal of the voltage comparator and is grounded; The first port is the output terminal of the voltage comparator, the second port is the negative phase input terminal, and the third port is the positive phase input terminal; the voltage comparator is an operational amplifier IC5A.

Images