Low-power-consumption zero-cross detection circuit, isolating switch power supply and equipment

Abstract

The embodiment of the utility model relates to a low-power-consumption zero-cross detection circuit, an isolating switch power supply and equipment. The low-power-consumption zero-cross detection circuit comprises an input circuit and an output circuit which are isolated from each other, the input circuit is connected to a primary circuit of the isolating switch power supply and is connected with a live wire and a zero wire on the primary circuit of the isolating switch power supply; the output circuit is connected with the MCU; the input circuit comprises a step-down unit and an optocoupler luminous source, wherein the first end of the optocoupler luminous source is connected with the step-down unit; wherein the voltage reduction unit is a capacitor or an inductor. According to the low-power-consumption zero-cross detection circuit, the voltage reduction unit is arranged to be the capacitor or the inductor, when the voltage reduction unit is connected to the primary circuit of the isolation switch power supply and is connected with the live wire and the zero wire, on one hand, the capacitor or the inductor can enable alternating current to pass, and capacitive reactance or inductive reactance can effectively reduce voltage; on the other hand, idle power is not generated when current flows through the capacitor or the inductor, circuit power consumption can be effectively reduced, and the heating phenomenon is reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of isolated power supplies, and in particular to a low-power zero-crossing detection circuit, an isolated switching power supply, and equipment. Background Art

[0002] Isolated power supplies, because there is no direct electrical connection between their input and output circuits, are often used in safety-critical scenarios such as home appliances. They isolate the mains power supply from the load power, thereby protecting subsequent load devices, systems, and personnel.

[0003] Zero-crossing detection refers to the system's detection of when the waveform passes through zero in an AC system. This is typically accomplished using a zero-crossing detection circuit. In practical applications, the zero-crossing moment is often used as a reference for determining load action or as a trigger signal for device functionality.

[0004] When a zero-crossing detection circuit is used in an isolated power supply product, it is usually necessary to adopt an isolated zero-crossing detection circuit. However, the isolated zero-crossing detection circuit in the existing technology generally has high power consumption, resulting in high standby power consumption of the equipment and high temperature of some product components. Utility Model Content

[0005] The embodiments of the present application provide a low-power zero-crossing detection circuit, an isolation switch power supply and a device, aiming to solve at least one of the above-mentioned technical problems.

[0006] In a first aspect, an embodiment of the present application provides a low-power zero-crossing detection circuit, the low-power zero-crossing detection circuit comprising:

[0007] Isolated input and output circuits;

[0008] The input circuit is connected to the primary circuit of the isolating switching power supply and is connected to the live wire and the neutral wire on the primary circuit of the isolating switching power supply; the output circuit is connected to the MCU;

[0009] The input circuit includes: a step-down unit, and an optocoupler light source whose first end is connected to the step-down unit; wherein the step-down unit is a capacitor or an inductor.

[0010] Compared with the prior art, the low-power zero-crossing detection circuit of the embodiment of the present application configures the step-down unit as a capacitor or inductor. When the step-down unit is connected to the primary circuit of the isolating switching power supply and connected to the live wire and the neutral wire, on the one hand, the capacitor or inductor can allow the alternating current to pass through, and the capacitive reactance or inductive reactance can effectively reduce the voltage. On the other hand, when the current flows through the capacitor or inductor, no useless power is generated, which can effectively reduce the circuit power consumption and reduce heat generation.

[0011] Optionally, one end of the step-down unit is connected to the live wire on the primary circuit of the isolating switching power supply, and the other end is connected to the optocoupler light source.

[0012] Optionally, one end of the step-down unit is connected to the neutral line of the primary circuit of the isolating switching power supply, and the other end is connected to the first end of the optocoupler light source.

[0013] Optionally, the optocoupler light source is a light emitting diode, the positive electrode of which is connected to the step-down unit, and the negative electrode is connected to the neutral line.

[0014] Optionally, the input circuit further includes: a diode, the anode of which is connected to the neutral line, and the cathode of which is connected between the step-down unit and the first end of the optocoupler light source.

[0015] Optionally, the capacitor is one of an X-type safety capacitor, a metal film capacitor, a ceramic capacitor, a ceramic capacitor, a polyester capacitor, and a chip capacitor.

[0016] Optionally, the output circuit includes: an optocoupler light receiver, a first end of which is connected to the MCU and a second end of which is grounded (GND);

[0017] A pull-up resistor (R1) has a first end connected to the DC voltage output end of the secondary circuit of the isolation switch power supply for inputting a DC voltage (VDD), and a second end connected between the first end of the optocoupler light receiver and the MCU.

[0018] Optionally, the optocoupler light receiver is a phototransistor, the collector of the phototransistor is connected to the MCU, the emitter is grounded (GND), and the second end of the pull-up resistor (R1) is connected between the collector and the MCU.

[0019] Optionally, the output circuit also includes: a second resistor, which is connected between the collector and the MCU, and one end of the second resistor is connected to the collector of the phototransistor and the second end of the pull-up resistor (R1), and the other end is connected to the MCU.

[0020] Optionally, the output circuit further includes: an anti-interference capacitor, one end of which is connected to the MCU and the other end is grounded (GND).

[0021] In a second aspect, an embodiment of the present application provides an isolated switching power supply, comprising the low-power zero-crossing detection circuit described in the first aspect of the embodiment of the present application.

[0022] In a third aspect, an embodiment of the present application provides a device, including the isolated switch power supply described in the second aspect of the embodiment of the present application, and the device also includes an MCU.

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure is a schematic diagram of a zero-crossing detection circuit structure provided in an exemplary embodiment.

[0025] Figure 2 The figure is a schematic diagram of an isolating switch power supply structure provided in an exemplary embodiment. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present application clearer, the embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

[0027] It should be clear that the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the embodiments of the present application.

[0028] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the embodiments of the present application. The singular forms "a," "the," and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0029] When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0030] In addition, in this application, unless otherwise specified, "plurality" refers to two or more. "And / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0031] The device in the embodiment of the present application specifically refers to a device including an isolated switching power supply and an isolated zero-crossing detection circuit, and the device may be an induction cooker, an air conditioner, a fan, etc.

[0032] Specifically, the device of the embodiment of the present application isolates the primary circuit connected to the mains and the subsequent circuit connected to the load by setting an isolation switch power supply in the device, thereby protecting the subsequent load equipment, system and personnel.

[0033] Furthermore, in order to achieve precise control of the subsequent load, or to trigger and start a certain function of the device, etc., the embodiment of the present application adds an isolated zero-crossing detection circuit to the device, connects it to the primary circuit of the isolated switching power supply, performs zero-crossing detection on the mains voltage, and then implements it based on the detected zero-crossing signal.

[0034] However, the isolated zero-crossing detection circuit in the prior art generally has the problem of high power consumption, which leads to problems such as high energy consumption of the device when in standby mode and easy heating of electronic components when in standby mode for a long time.

[0035] To this end, an embodiment of the present application provides a low-power zero-crossing detection circuit, which has low power consumption compared to the zero-crossing detection circuit of the prior art. When the zero-crossing detection circuit of the embodiment of the present application is applied to an isolating switching power supply, the standby power consumption of the isolating switching power supply product can be effectively reduced. When the isolating switching power supply product of the embodiment of the present application is applied to equipment such as air conditioners and fans, the standby power consumption of the equipment can be effectively reduced. In addition, the zero-crossing detection circuit, isolating switching power supply and equipment of the embodiment of the present application can at least slow down the occurrence of heating of electronic components when in standby mode for a long time.

[0036] The zero-crossing detection circuit of an embodiment of the present application is described in detail below: A low-power zero-crossing detection circuit of an embodiment of the present application includes: an isolated input circuit and an output circuit.

[0037] The input circuit is connected to the primary circuit of the isolating switching power supply and is connected to the live and neutral wires of the primary circuit of the isolating switching power supply. The input circuit includes a step-down unit and an optocoupler light source with a first end connected to the step-down unit. When current flows from the live wire through the step-down unit and the optocoupler light source, the optocoupler light source converts electricity into light and emits light.

[0038] In an exemplary embodiment, the input circuit includes a step-down unit and an optocoupler light source, wherein one end of the step-down unit is connected to the live wire of the primary circuit of the isolating switching power supply, and the other end is connected to the first end of the optocoupler light source. The second end of the optocoupler light source is connected to the neutral wire of the primary circuit of the isolating switching power supply to form an input circuit. When the AC voltage is in the positive half cycle, the current enters from the live wire and flows through the step-down unit and the optocoupler light source, and the first and second ends of the optocoupler light source are turned on to realize electro-optical conversion and light emission. When the AC voltage is in the negative half cycle, the first and second ends of the optocoupler light source are not turned on, the input circuit is disconnected, and the optocoupler light source does not emit light. Preferably, in an embodiment of the present application, the optocoupler light source is a light emitting diode, the positive pole of which is connected to the step-down unit, and the negative pole is connected to the neutral wire.

[0039] The step-down unit is a capacitor or an inductor. When an AC voltage flows through a capacitor or an inductor, the current flowing through it is determined by the capacitive reactance of the capacitor or the inductive reactance of the inductor. In an embodiment of the present application, the voltage is stepped down by a capacitor or an inductor. On the one hand, the capacitor or inductor can allow AC to pass through, and the capacitive reactance or inductive reactance can effectively reduce the voltage. On the other hand, when the current flows through the capacitor or inductor, no useless power is generated, which can effectively reduce the power consumption of the zero-crossing detection circuit, thereby reducing the heating phenomenon of the printed circuit board PCBA. Preferably, the capacitor is any one of an X-type safety capacitor, a metal film capacitor, a ceramic capacitor, a ceramic capacitor, a polyester capacitor, a chip capacitor, etc.

[0040] Preferably, in an embodiment of the present application, the input circuit further includes a diode, the positive electrode of the diode is connected to the neutral line, and the negative electrode is connected between the step-down unit and the first end of the optocoupler light source. When the AC voltage is in the positive half cycle, since the diode is unidirectionally conductive, the current enters from the live wire and flows through the step-down unit and the optocoupler light source, and the first end and the second end of the optocoupler light source are conductive, realizing electro-optical conversion and luminescence. When the AC voltage is in the negative half cycle, the current enters the input circuit from the neutral line and flows out after passing through the diode and the step-down unit. At this time, the current does not pass through the optocoupler light source, and its first end and the second end are not conductive, and the optocoupler light source does not emit light. In addition, the setting of the diode can also effectively prevent the influence of mains power fluctuations on the optocoupler light source.

[0041] It should be understood by those skilled in the art that the live and neutral wires of the AC power supply are polarity descriptions of single-phase AC power, and the input can also be used by swapping the polarity of the live and neutral wires. It can also be used by replacing the live and neutral wires of the input circuit with any two poles of three-phase AC power. Specifically, in other embodiments, one end of the step-down unit is connected to the neutral wire of the primary circuit of the isolating switching power supply, and the other end is connected to the first end of the optocoupler light source, and the second end of the optocoupler light source is connected to the live wire of the primary circuit of the isolating switching power supply to form an input circuit. Different from the above exemplary embodiments, in these embodiments, when the AC voltage is in the negative half cycle, the current enters from the neutral wire and flows through the step-down unit and the optocoupler light source, the first end and the second end of the optocoupler light source are conductive, and when the current flows through, the optocoupler light source converts electricity into light and emits light. When the AC voltage is in the positive half cycle, the input circuit is disconnected, the first end and the second end of the optocoupler light source are not conductive, and the optocoupler light source does not emit light.

[0042] The output circuit is connected to the MCU. In some exemplary embodiments, the output circuit includes: an optocoupler light receiver and a pull-up resistor.

[0043] The first end of the optocoupler light receiver is connected to the MCU, and the second end is grounded (GND). The first end of the pull-up resistor is connected to the DC voltage output end of the secondary circuit of the isolating switch power supply for inputting a DC voltage, and the second end is connected between the first end of the optocoupler light receiver and the MCU. When the optocoupler light source in the input circuit emits light, the optocoupler light receiver receives light and connects the first end and the second end to achieve photoelectric conversion, and the current flows through the pull-up resistor and the optocoupler light receiver through the DC voltage output end. At this time, the output circuit outputs a low level to the signal port of the MCU. When the optocoupler light source in the input circuit does not emit light, the optocoupler light receiver does not conduct, but since the DC voltage output end of the secondary circuit of the isolating switch power supply still inputs a DC voltage, at this time, the current is input to the MCU signal port through the pull-up resistor, that is, the output circuit outputs a high level to the signal port of the MCU.

[0044] Preferably, the optocoupler light receiver is a phototransistor, the collector of the phototransistor is connected to the MCU, the emitter is grounded (GND), and the second end of the pull-up resistor is connected between the collector and the MCU.

[0045] In other exemplary embodiments, the output circuit further includes a second resistor connected between the collector and the MCU, with one end of the second resistor connected to the collector of the phototransistor and the second end of the pull-up resistor, and the other end connected to the MCU. The second resistor can function as a voltage divider and current limiter.

[0046] The output circuit further includes an anti-interference capacitor, one end of which is connected to the MCU and the other end is grounded (GND). The anti-interference capacitor can effectively prevent electromagnetic interference.

[0047] like Figure 1 、 2 As shown, an exemplary low-power zero-crossing detection circuit of the present application is shown. The low-power zero-crossing detection circuit includes an optocoupler U1, which includes an isolated light-emitting diode and a phototransistor. The light-emitting diode serves as the light source of the optocoupler, and the phototransistor serves as the light receiver of the optocoupler. The input circuit including the light-emitting diode and the output circuit including the phototransistor are isolated by the optocoupler U1. Preferably, the model of the optocoupler U1 is EL817.

[0048] The anode A of the light emitting diode is connected to the capacitor C1 and then connected to the primary live wire ACL of the isolating switch power supply. The anode A of the light emitting diode is also connected to the cathode of the diode D1. Figure 2 As shown in the dotted box. The cathode K of the light-emitting diode is connected to the neutral line ACN of the primary side of the isolating switching power supply. The cathode K is also connected to the anode of diode D1. Diode D1 is connected in parallel with the light-emitting diode. Preferably, capacitor C1 is a 104 capacitor with a capacity of 0.1uF and a withstand voltage of 275V. The model of diode D1 is IN4007.

[0049] The base of the phototransistor is exposed to light. The collector C of the phototransistor is connected to a pull-up resistor R1 and then to the DC voltage output terminal of the secondary circuit of the isolating switch power supply, thereby inputting a DC voltage VDD. Preferably, VDD is +5V. Preferably, the pull-up resistor has a resistance of 68KΩ. The collector C is also connected to a second resistor R2 and then to the signal port of the MCU, thereby outputting high and low voltage levels to the MCU. Preferably, the resistance of the second resistor R2 is 1KΩ.

[0050] The emitter E of the phototransistor is grounded to GND. One end of the anti-interference capacitor C2 is connected between the MCU and the second resistor R2, and the other end is grounded to GND. Preferably, the anti-interference capacitor C2 is a 102 capacitor with a capacity of 1000PF and a withstand voltage of 50V.

[0051] The zero-crossing detection circuit of the embodiment of the present application can accurately detect the zero-crossing signal of the AC voltage of the primary circuit of the isolated switching power supply.

[0052] Specifically, when the AC voltage is in the positive half-cycle, current flows through the live wire into capacitor C1 in the input circuit and through the LED. The LED's anode A and cathode K are conducting, achieving electro-optical conversion and emitting light. The base of the phototransistor receives light, turning it on. The DC voltage VDD provides a stable voltage for the output circuit, and current flows through pull-up resistor R1 and the phototransistor. At this point, the output circuit outputs a low level to the MCU's signal port.

[0053] When the AC voltage is in the negative half cycle, current enters the input circuit through the neutral line, flows through diode D1 and capacitor C1, and then exits the hot line. At this point, the anode A and cathode K of the LED are not conducting, and the LED does not emit light. The base of the phototransistor is not receiving light, causing it to shut down. DC voltage VDD provides a stable voltage for the output circuit. Current flows through pull-up resistor R1 and second resistor R2 and enters the MCU. At this point, the output circuit outputs a high level to the MCU's signal port.

[0054] The capacitor C1 is configured to allow AC power to pass through, and on the other hand, it can effectively reduce the voltage without generating useless power, thereby greatly reducing the power consumption of the zero-crossing detection circuit.

[0055] An embodiment of the present application provides an isolated switching power supply, comprising a low-power zero-crossing detection circuit according to any one of the exemplary implementations of the present application corresponding to the above-mentioned embodiment.

[0056] The present application also provides a device comprising an isolating switch power supply according to any one of the exemplary embodiments of the present application corresponding to the above embodiments and an MCU. The isolating switch power supply is connected to the MCU. Preferably, the MCU is a single chip microcomputer.

[0057] Those skilled in the art will appreciate that the low-power zero-crossing detection circuit of the present invention can be provided in conjunction with an industrial frequency transformer isolation power supply, and can also achieve the purpose of reducing power consumption and heat generation of the zero-crossing circuit.

[0058] Those skilled in the art will appreciate that embodiments of the present invention may be provided as systems or computer program products. Thus, the present invention may take the form of a fully hardware embodiment, a fully software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0059] The structure of the low-power zero-crossing detection circuit defined in the above method steps is the same as the structural principle of the low-power zero-crossing detection circuit in the aforementioned device embodiment, and will not be repeated here. It should be understood that the embodiments of the present application are not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the embodiments of the present application is limited only by the appended claims.

[0060] The above-described embodiments merely represent several implementation methods of the embodiments of the present application. Although the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art may make several variations and improvements without departing from the concept of the embodiments of the present application, and these variations and improvements fall within the scope of protection of the embodiments of the present application.

Claims

1. Low power consumption zero-crossing detection circuit, characterized in that: include: Isolated input circuit and output circuit; The input circuit is connected to the primary circuit of the isolating switch power supply and is connected to the live wire and the neutral wire on the primary circuit of the isolating switch power supply; the output circuit is connected to the MCU; The input circuit includes: a step-down unit, and an optocoupler light source whose first end is connected to the step-down unit; wherein the step-down unit is a capacitor or an inductor.

2. The circuit according to claim 1, characterized in that: One end of the step-down unit is connected to the live wire on the primary circuit of the isolating switch power supply, and the other end is connected to the photocoupler light source.

3. The circuit according to claim 1, characterized in that: The light source of the optocoupler is a light emitting diode, the positive electrode of which is connected to the step-down unit, and the negative electrode of which is connected to the neutral line.

4. The circuit according to claim 1, characterized in that The input circuit further comprises: The diode has an anode connected to the neutral line and a cathode connected between the step-down unit and the first end of the optical coupler light source.

5. The circuit according to claim 1, characterized in that: The capacitor is one of an X-type safety capacitor, a metal film capacitor, a ceramic chip capacitor, a ceramic capacitor, a polyester capacitor, and a chip capacitor.

6. The circuit according to claim 1, characterized in that The output circuit comprises: An optocoupler light receiver, a first end of which is connected to the MCU and a second end of which is grounded (GND); The pull-up resistor has a first end connected to the DC voltage output end of the secondary circuit of the isolation switch power supply for inputting a DC voltage, and a second end connected between the first end of the optical coupler light receiver and the MCU.

7. The circuit according to claim 6, characterized in that: The optocoupler light receiver is a phototransistor, the collector of the phototransistor is connected to the MCU, the emitter is grounded (GND), and the second end of the pull-up resistor is connected between the collector and the MCU.

8. The circuit according to claim 7, characterized in that The output circuit further includes: A second resistor is connected between the collector and the MCU, one end of the second resistor is connected to the collector of the phototransistor and the second end of the pull-up resistor, and the other end is connected to the MCU.

9. The circuit according to claim 6, characterized in that The output circuit further includes: An anti-interference capacitor, one end of which is connected to the MCU and the other end is grounded (GND).

10. An isolating switching power supply, characterized in that: The invention comprises the low power consumption zero-crossing detection circuit as described in any one of claims 1 to 9.

11. A device, characterized in that: The device comprises the isolating switch power supply as described in claim 10, and further comprises an MCU.

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