Power supply automatic switching circuit and electric appliance
By combining rectifier modules, voltage divider modules, voltage comparator modules, and switching modules with transformers, the complexity and high cost of switching between different mains power sources are solved, achieving fast and low-cost automatic power switching.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- AUX AIR CONDITIONER CO LTD
- Filing Date
- 2025-05-27
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technologies require manual cable replacement or MCU software identification and switching when adapting to different AC power supplies, which is prone to errors, inefficient and costly, and makes it difficult to achieve rapid response, especially in application scenarios without MCU.
The system combines a rectifier module, a voltage divider module, a voltage comparator module, and a switch module with a transformer. By automatically controlling the switching of the transformer coil through voltage comparison, it achieves automatic power supply adaptation and rapid response.
It enables quick and low-cost switching to the appropriate power level without manual intervention or MCU control under different mains power sources, simplifying the electronic control system and reducing complexity and cost.
Smart Images
Figure CN224264705U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electrical technology, and in particular to automatic power switching circuits. Background Technology
[0002] Currently, mains power standards vary across countries, and even within the same country, multiple mains power sources exist. For example, in the United States, some areas use 230V / 60Hz mains, while others use 115V / 60Hz. Furthermore, for some AC loads in air conditioners, such as 24V AC thermostats and 24V AC contactors, in addition to using DC-to-AC circuits to provide the required AC power, tapped or other linear transformers supporting multiple input ranges are often used for power supply (e.g., linear transformers supporting multiple input ranges and single output ranges, with multiple input ranges including AC 230V or 115V and single output range being AC 24V). These transformers essentially have multiple input terminals, requiring switching to the corresponding range depending on the mains power. Switching to the appropriate range often requires manual wiring or using an MCU to sample the power supply voltage and control a relay to switch ranges via software identification.
[0003] Manual line replacement is prone to errors and inefficient, while MCU software identification solutions are complex and lagging. Since the MCU itself needs power, the common approach is to first supply power to the MCU with an independent switching power supply system, and voltage identification and switching can only be performed after the MCU is working normally. This not only makes the power control system complex and costly, but also makes it unsuitable for low-cost or MCU-less application scenarios.
[0004] Designing an automatic switching circuit that can adapt to two mains power sources, with low cost and fast response, is a technical problem that needs to be solved. Utility Model Content
[0005] The purpose of this application is to provide an automatic switching circuit that adapts to two mains power sources, featuring low cost and fast response.
[0006] To achieve the above objectives, one or more embodiments of this application adopt the following technical solutions.
[0007] In a first aspect, embodiments of this application provide an automatic power switching circuit, including a rectifier module, a voltage divider module, a voltage comparison module, a switching module, and a transformer;
[0008] The two input terminals of the rectifier module are used to connect to alternating current, wherein the voltage of the alternating current is one of at least two voltages;
[0009] The first output terminal of the rectifier module is connected to the first terminal of the voltage divider module, the second output terminal of the rectifier module is connected to the second terminal of the voltage divider module, and the middle terminal of the voltage divider module is connected to the first terminal of the voltage comparator module.
[0010] The second terminal of the voltage comparison module is used to connect to a low-voltage power supply; the voltage of the low-voltage power supply is lower than the voltage of the AC power.
[0011] The third terminal of the voltage comparison module is connected to the control terminal of the switching module;
[0012] The fixed contact of the switch module is connected to the first input terminal of AC power; the first variable contact of the switch module is connected to the first terminal of the primary winding of the transformer; the second variable contact of the switch module is connected to the second terminal of the primary winding of the transformer; and the third terminal of the primary winding of the transformer is connected to the second input terminal of AC power. The secondary winding of the transformer is used to connect the load.
[0013] When the AC voltage is a first type of voltage, the voltage after rectification, filtering, and voltage division by the rectifier module and the voltage divider module causes the voltage comparison module to output a first type of signal; when the AC voltage is a second type of voltage, the voltage after rectification, filtering, and voltage division by the rectifier module and the voltage divider module causes the voltage comparison module to output a second type of signal. The filtering function can be set in either the rectifier module or the voltage divider module.
[0014] Optionally, the voltage comparison module includes an adjustable parallel regulator, the first end of which is connected to the middle terminal of the voltage divider module, the second end of which is connected to the low-voltage power supply, and the third end of which is connected to the control terminal of the switching module.
[0015] Optionally, the adjustable parallel voltage regulator is a TL431 chip or a TL432 chip; the REF terminal of the TL431 chip or the TL432 chip is connected to the middle terminal of the voltage divider module, the CATHODE terminal of the TL431 chip or the TL432 chip is used to connect to the low-voltage power supply, and the ANODE terminal of the TL431 chip or the TL432 chip is connected to the control terminal of the switching module.
[0016] Optionally, the switching module includes a switching transistor and a relay;
[0017] The first terminal of the switching transistor is grounded, the second terminal of the switching transistor is connected to the first terminal of the relay coil, the control terminal of the switching transistor is connected to the third terminal of the voltage comparison module, and the second terminal of the relay coil is connected to the low-voltage power supply.
[0018] Alternatively, the first end of the switching transistor is connected to the low-voltage power supply, the second end of the switching transistor is connected to the first end of the relay coil, the control end of the switching transistor is connected to the third end of the voltage comparison module, and the second end of the relay coil is grounded.
[0019] Optionally, the switching module further includes a first resistor unit and a diode unit;
[0020] The first resistor unit is connected between the control terminal of the switching transistor and the third terminal of the voltage comparison module;
[0021] The diode unit is connected in parallel with the relay coil.
[0022] Optionally, the voltage divider module includes a second resistor unit and a third resistor unit;
[0023] The first end of the second resistor unit is connected to the first output terminal of the rectifier module, the second end of the second resistor unit is connected to the first end of the third resistor unit, and the second end of the third resistor unit is connected to the second output terminal of the rectifier module.
[0024] Optionally, the rectifier module includes a full-wave rectifier bridge.
[0025] Optionally, the automatic power switching circuit further includes a capacitor connected between the first output terminal and the second output terminal of the rectifier module.
[0026] Secondly, embodiments of this application provide an automatic power switching circuit, including a rectifier module, a voltage divider module, a voltage comparison module, a switching module, and a transformer;
[0027] The two input terminals of the rectifier module are used to connect to alternating current, wherein the voltage of the alternating current is one of at least two voltages;
[0028] The first output terminal of the rectifier module is connected to the first terminal of the voltage divider module, the second output terminal of the rectifier module is connected to the second terminal of the voltage divider module, and the middle terminal of the voltage divider module is connected to the first terminal of the voltage comparator module.
[0029] The second terminal of the voltage comparison module is used to connect to a low-voltage power supply; the voltage of the low-voltage power supply is lower than the voltage of the AC power.
[0030] The third terminal of the voltage comparison module is connected to the control terminal of the switching module;
[0031] The fixed contact of the switch module is used to connect one end of the load, the first variable contact of the switch module is connected to the first end of the secondary coil of the transformer, the second variable contact of the switch module is connected to the second end of the secondary coil of the transformer, and the third end of the secondary coil of the transformer is used to connect to the other end of the load; the primary coil of the transformer is used to connect to the AC power.
[0032] Thirdly, embodiments of this application provide an electrical appliance, which includes the power automatic switching circuit described in the first or second aspect.
[0033] Compared with the prior art, this application has the following advantages:
[0034] The power automatic switching circuit provided in this application embodiment does not require an MCU and software. The voltage comparison module uses a device with comparison function to identify two or more mains power supplies of different sizes, and then controls the different coils of the transformer to be connected to the circuit to obtain the required output voltage. Attached Figure Description
[0035] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0036] Figure 1 A schematic diagram of an automatic power switching circuit provided in an embodiment of this application;
[0037] Figure 2 A schematic diagram illustrating the connection of a switch module to the secondary coil of a transformer, provided in an embodiment of this application;
[0038] Figure 3 A voltage comparison module provided in this application embodiment may include a schematic diagram of an adjustable parallel voltage regulator;
[0039] Figure 4 A schematic diagram of a voltage comparison module provided in an embodiment of this application may include a TL431 chip;
[0040] Figure 5 A schematic diagram showing a switching module that may include a switching transistor and a relay, provided for an embodiment of this application;
[0041] Figure 6 A schematic diagram showing a pressure module provided in an embodiment of this application may include a second resistor unit R1 and a third resistor unit R2;
[0042] Figure 7A schematic diagram of a rectifier module provided in an embodiment of this application may include a full-wave rectifier bridge. Detailed Implementation
[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of this application, not all embodiments. The components of the embodiments of this application described in the accompanying drawings can generally be arranged and designed in various different configurations.
[0044] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0045] In the description of this application, it should be noted that:
[0046] Relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations;
[0047] "Connection" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium.
[0048] This application provides an automatic power switching circuit, such as... Figure 1 The automatic power switching circuit includes a rectifier module, a voltage divider module, a voltage comparator module, a switching module, and a transformer. The rectifier module, voltage divider module, and voltage comparator module have the following connection relationships:
[0049] The two input terminals of the rectifier module are used to connect to AC power, and the AC power voltage is one of at least two voltages, that is, it can be adapted to at least two AC mains power sources.
[0050] The first output terminal of the rectifier module is connected to the first terminal of the voltage divider module;
[0051] The second output terminal of the rectifier module is connected to the second terminal of the voltage divider module;
[0052] The middle terminal of the voltage divider module is connected to the first terminal of the voltage comparator module;
[0053] The second terminal of the voltage comparator module is used to connect to the low-voltage power supply VCC. The voltage of the low-voltage power supply VCC is lower than that of the AC power supply. It can be generated by a power supply circuit that converts the AC power into low-voltage DC power.
[0054] The third terminal of the voltage comparator module is connected to the control terminal of the switch module.
[0055] There are two ways to connect the switch module and the transformer:
[0056] One type is where the switching module connects to the primary coil of the transformer, such as... Figure 1 The fixed contact of the switching module is connected to the first AC input terminal. The first variable contact of the switching module is connected to the first terminal of the primary winding of the transformer. The second variable contact of the switching module is connected to the second terminal of the primary winding of the transformer. The third terminal of the primary winding of the transformer is connected to the second AC input terminal. The secondary winding of the transformer is used to connect the load. The switching module can also have more variable contacts, connecting to different terminals of the primary winding. The different terminals of the primary winding represent multiple input power levels. One variable contact of the switching module can be used as a normally closed contact, and the others can be used as normally open contacts.
[0057] One type is where the switching module connects to the secondary coil of the transformer, such as... Figure 2 The fixed contacts of the switching module are used to connect one end of the load. The first variable contact of the switching module is connected to the first end of the secondary coil of the transformer, the second variable contact of the switching module is connected to the second end of the secondary coil of the transformer, and the third end of the secondary coil of the transformer is used to connect to the other end of the load. The primary coil of the transformer is used to connect to AC power. The switching module can also have more variable contacts to connect to different ends of the secondary coil. The following description uses the example of the switching module connecting to the primary coil of the transformer. The technical features of the following implementation can be applied to the implementation of the switching module connecting to the secondary coil of the transformer.
[0058] The working principle of the automatic power switching circuit is as follows:
[0059] The voltage divider module divides the bus voltage after rectification and filtering by the rectifier module, allowing the divided voltage value under different power supplies to be compared with the reference voltage of the voltage comparator module. The voltage comparator module controls the state of the switching module based on the different comparison results under different power supplies. The switching module can have a single-pole double-throw switch relay or a single-pole multi-throw switch relay, so that the corresponding coil tap of the transformer is connected to the circuit to obtain the corresponding output voltage. This realizes the detection and automatic switching of dual or multiple power supplies, achieving the effect of fast and direct automatic switching of the corresponding tap without manual intervention for line replacement and without MCU detection and software logic judgment.
[0060] The voltage comparison module can be implemented using the principle of an adjustable parallel voltage regulator, meaning that the voltage comparison module can include an adjustable parallel voltage regulator.
[0061] like Figure 3 The adjustable parallel voltage regulator has the following connection relationship:
[0062] The first end of the adjustable parallel voltage regulator is connected to the middle end of the voltage divider module;
[0063] The second terminal of the adjustable parallel voltage regulator is used to connect to the low-voltage power supply VCC;
[0064] The third terminal of the adjustable parallel voltage regulator is connected to the control terminal of the switching module.
[0065] The adjustable parallel voltage regulator can be a TL431 chip or a TL432 chip.
[0066] Figure 4 Taking the TL431 chip as an example, the following connection relationships exist:
[0067] The REF terminal of the TL431 or TL432 chip is connected to the middle terminal of the voltage divider module;
[0068] The CATHODE pin of the TL431 or TL432 chip is used to connect to the low-voltage power supply VCC.
[0069] The ANODE pin of the TL431 or TL432 chip is connected to the control pin of the switch module.
[0070] The switching module can be implemented based on the principle of a relay. The switching module can include a switching transistor and a relay. When the power supply voltage required by the relay is higher than that of the TL431 or TL432 chip, a transistor or MOSFET is used to amplify the current of the relay.
[0071] like Figure 5 The switch module has the following connection relationships:
[0072] The first terminal of switching transistor Q1 is grounded, the second terminal of switching transistor Q1 is connected to the first terminal of the relay coil, the control terminal of switching transistor Q1 is connected to the third terminal of the voltage comparator module, and the second terminal of the relay coil is connected to the low-voltage power supply VCC. Alternatively, the first terminal of switching transistor Q1 is connected to the low-voltage power supply VCC, the second terminal of switching transistor Q1 is connected to the first terminal of the relay coil, the control terminal of switching transistor Q1 is connected to the third terminal of the voltage comparator module, and the second terminal of the relay coil is grounded.
[0073] like Figure 5 The switching module may also include a first resistor unit R4, which is connected between the control terminal of the switching transistor Q1 and the third terminal of the voltage comparator module. The first resistor unit R4 has a current-limiting function to meet the current requirements of the transistor.
[0074] like Figure 5The switching module may also include a resistor R3, which is connected between the CATHODE terminal of the TL431 or TL432 chip and the low-voltage power supply VCC. The resistor R3 has the function of current limiting to meet the current requirements of the TL431 or TL432 chip.
[0075] like Figure 5 The switching module may also include a diode unit D1, which is connected in parallel with the relay coil. The cathode of diode unit D1 is connected to one end of the low-voltage power supply VCC of the relay coil, and the anode of diode unit D1 is connected to the other end of the relay coil. The function of diode unit D1 is to eliminate the back electromotive force generated when the coil is de-energized, thereby protecting other electronic components in the circuit.
[0076] like Figure 6 The voltage divider module may include a second resistor unit R1 and a third resistor unit R2. The second resistor unit R1 and the third resistor unit R2 may be composed of multiple resistors or a single resistor.
[0077] like Figure 6 The second resistor unit R1 and the third resistor unit R2 have the following connection relationship:
[0078] The first end of the second resistor unit R1 is connected to the first output end of the rectifier module;
[0079] The second end of the second resistor unit R1 is connected to the first end of the third resistor unit R2;
[0080] The second end of the third resistor unit R2 is connected to the second output end of the rectifier module.
[0081] like Figure 6 When the voltage drop across the third resistor unit R2 is greater than 2.5V, the TL431 chip conducts, the switching transistor Q1 conducts, the relay coil is energized, and the relay switch switches from contact 4 and contact 0 conducting to contact 4 and contact 3 conducting. Conversely, when the voltage drop across the third resistor unit R2 is less than 2.5V, the TL431 chip does not conduct, the switching transistor Q1 does not conduct, and the relay switch remains normally closed, i.e., contact 4 and contact 0 are conducting. The normally closed contact represents the lower transformer output by default.
[0082] like Figure 7 The rectifier module may include a full-wave rectifier bridge, which consists of four diodes.
[0083] like Figure 7 The automatic power switching circuit may also include capacitor E1, which is connected between the first output terminal and the second output terminal of the rectifier module. Capacitor E1 serves a filtering function. Alternatively, a capacitor can be placed between the middle terminal of the voltage divider module and ground (GND) to filter the output voltage of the voltage divider module.
[0084] Based on the above embodiments, this application also provides an electrical appliance, such as an air conditioner, which includes the above-described automatic power switching circuit.
[0085] The apparatus and system embodiments described above are merely illustrative. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement these embodiments without any creative effort.
[0086] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. An automatic power switching circuit, characterized in that, It includes rectifier modules, voltage divider modules, voltage comparator modules, switching modules, and transformers; The two input terminals of the rectifier module are used to connect to alternating current, wherein the voltage of the alternating current is one of at least two voltages; The first output terminal of the rectifier module is connected to the first terminal of the voltage divider module, the second output terminal of the rectifier module is connected to the second terminal of the voltage divider module, and the middle terminal of the voltage divider module is connected to the first terminal of the voltage comparator module. The second terminal of the voltage comparison module is used to connect to a low-voltage power supply; the voltage of the low-voltage power supply is lower than the voltage of the AC power. The third terminal of the voltage comparison module is connected to the control terminal of the switching module; The fixed contact of the switch module is connected to the first input terminal of AC power; the first variable contact of the switch module is connected to the first terminal of the primary winding of the transformer; the second variable contact of the switch module is connected to the second terminal of the primary winding of the transformer; and the third terminal of the primary winding of the transformer is connected to the second input terminal of AC power. The secondary winding of the transformer is used to connect the load. When the AC voltage is a first type of voltage, the voltage after rectification, filtering, and voltage division by the rectifier module and the voltage divider module causes the voltage comparison module to output a first type of signal; when the AC voltage is a second type of voltage, the voltage after rectification, filtering, and voltage division by the rectifier module and the voltage divider module causes the voltage comparison module to output a second type of signal.
2. The automatic power switching circuit as described in claim 1, characterized in that, The voltage comparison module includes an adjustable parallel regulator. The first end of the adjustable parallel regulator is connected to the middle end of the voltage divider module, the second end of the adjustable parallel regulator is used to connect to the low-voltage power supply, and the third end of the adjustable parallel regulator is connected to the control end of the switching module.
3. The automatic power switching circuit as described in claim 2, characterized in that, The adjustable parallel voltage regulator is a TL431 chip or a TL432 chip; the REF terminal of the TL431 chip or the TL432 chip is connected to the middle terminal of the voltage divider module, the CATHODE terminal of the TL431 chip or the TL432 chip is used to connect to the low-voltage power supply, and the ANODE terminal of the TL431 chip or the TL432 chip is connected to the control terminal of the switching module.
4. The automatic power switching circuit as described in claim 2, characterized in that, The switching module includes a switching transistor and a relay; The first terminal of the switching transistor is grounded, the second terminal of the switching transistor is connected to the first terminal of the relay coil, the control terminal of the switching transistor is connected to the third terminal of the voltage comparison module, and the second terminal of the relay coil is connected to the low-voltage power supply. Alternatively, the first end of the switching transistor is connected to the low-voltage power supply, the second end of the switching transistor is connected to the first end of the relay coil, the control end of the switching transistor is connected to the third end of the voltage comparison module, and the second end of the relay coil is grounded.
5. The automatic power switching circuit as described in claim 4, characterized in that, The switching module further includes a first resistor unit and a diode unit; The first resistor unit is connected between the control terminal of the switching transistor and the third terminal of the voltage comparison module; The diode unit is connected in parallel with the relay coil.
6. The automatic power switching circuit as described in claim 1, characterized in that, The voltage divider module includes a second resistor unit and a third resistor unit; The first end of the second resistor unit is connected to the first output terminal of the rectifier module, the second end of the second resistor unit is connected to the first end of the third resistor unit, and the second end of the third resistor unit is connected to the second output terminal of the rectifier module.
7. The automatic power switching circuit as described in claim 1, characterized in that, The rectifier module includes a full-wave rectifier bridge.
8. The automatic power switching circuit as described in claim 1, characterized in that, The automatic power switching circuit also includes a capacitor connected between the first output terminal and the second output terminal of the rectifier module.
9. An automatic power switching circuit, characterized in that, It includes rectifier modules, voltage divider modules, voltage comparator modules, switching modules, and transformers; The two input terminals of the rectifier module are used to connect to alternating current, wherein the voltage of the alternating current is one of at least two voltages; The first output terminal of the rectifier module is connected to the first terminal of the voltage divider module, the second output terminal of the rectifier module is connected to the second terminal of the voltage divider module, and the middle terminal of the voltage divider module is connected to the first terminal of the voltage comparator module. The second terminal of the voltage comparison module is used to connect to a low-voltage power supply; the voltage of the low-voltage power supply is lower than the voltage of the AC power. The third terminal of the voltage comparison module is connected to the control terminal of the switching module; The fixed contact of the switch module is used to connect one end of the load, the first variable contact of the switch module is connected to the first end of the secondary coil of the transformer, the second variable contact of the switch module is connected to the second end of the secondary coil of the transformer, and the third end of the secondary coil of the transformer is used to connect to the other end of the load; the primary coil of the transformer is used to connect to the AC power.
10. An electrical appliance, characterized in that, The electrical appliance includes the automatic power switching circuit according to any one of claims 1 to 9.