Circuit with voltage detection and double-relay series-parallel connection PTC (Positive Temperature Coefficient) control

Abstract

The utility model discloses a circuit with voltage detection and double-relay series-parallel connection PTC control, which comprises a second relay, a first relay, a rectifier bridge for supplying power to an electrolytic capacitor, a voltage sampling circuit, a voltage comparison circuit and an MCU, wherein the second relay, the first relay and the rectifier bridge are sequentially connected in series between a live wire terminal and a zero wire terminal; a PTC (Positive Temperature Coefficient) is arranged between a front wiring end and a rear wiring end of the first relay, the first relay and the second relay are connected with the relay control circuit, the voltage sampling circuit is electrically connected with the voltage comparison circuit, and the voltage comparison circuit and the relay control circuit are electrically connected with the MCU. The power supply of the fan is controlled through the first relay and the second relay which are connected in series, and when the voltage is too high, the live wire and the zero wire are disconnected through the second relay to stop power supply, so that the safety of a rear-end circuit is ensured; and meanwhile, through the PTC connected with the first relay in parallel, the electrolytic capacitor can be prevented from being burnt out by high current instantly generated during power-on, and the failure rate is reduced.

Description

Technical Field

[0001] The utility model relates to a circuit with voltage detection double relays connected in series and parallel with PTC control. Background Art

[0002] The DC brushless fan in the air conditioner needs to be controlled by a fan speed control board. There are many fan speed control boards produced now for use in DC brushless fan speed control. The failure rate of this type of fan speed control board controller is very high, so there are also many after-sales feedback problems. Utility Model Content

[0003] In view of the above problems, the utility model provides a circuit with voltage detection double relays connected in series and parallel PTC control, which effectively solves the problems pointed out in the background technology.

[0004] The technical solution adopted by the utility model is:

[0005] A circuit with voltage detection double relays connected in series and parallel with PTC control comprises a second relay, a first relay and a rectifier bridge for supplying power to an electrolytic capacitor, which are sequentially connected in series between a live wire terminal and a neutral wire terminal, a voltage sampling circuit, a voltage comparison circuit and an MCU, wherein a PTC is arranged between front and rear terminals of the first relay, the first relay and the second relay are connected to a relay control circuit, the voltage sampling circuit is electrically connected to a voltage comparison circuit, and the voltage comparison circuit and the relay control circuit are electrically connected to the MCU.

[0006] Preferably, a varistor is provided between the live wire terminal and the neutral wire terminal.

[0007] Preferably, the voltage comparison circuit is used to sample the voltage between the live wire terminal and the neutral wire terminal, and the voltage comparison circuit compares the data sampled by the voltage sampling circuit with a preset value, and transmits the comparison result to the MCU.

[0008] Preferably, the voltage comparison circuit is provided with an optocoupler electrically connected to the MCU, and the optocoupler transmits the comparison result of the voltage comparison circuit to the MCU.

[0009] The optocoupler can transmit the comparison result of the voltage comparison circuit to the MCU. When the adopted voltage reaches the preset value, it indicates that the voltage is too high. The MCU will control the second relay to disconnect through the relay control circuit to stop the power supply to the fan.

[0010] The utility model controls the power supply of the fan by means of a first relay and a second relay which are arranged in series. When the voltage is too high, the live wire and the neutral wire are disconnected by the second relay to stop the power supply, thereby ensuring the safety of the back-end circuit. At the same time, the PTC connected in parallel with the first relay can prevent the electrolytic capacitor from being burned out by the large current generated instantaneously when power is turned on, thereby reducing the failure rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a circuit diagram of the utility model. DETAILED DESCRIPTION

[0012] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0013] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0014] In addition, 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", "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.

[0015] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "plurality" means two or more, unless otherwise clearly defined.

[0016] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0017] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0018] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0019] like Figure 1 As shown, a circuit with voltage detection dual relay series-parallel PTC control includes a second relay 3, a first relay 4 and a rectifier bridge 6 for powering an electrolytic capacitor 5, which are sequentially connected in series between a live wire terminal 1 and a neutral wire terminal 2, as well as a voltage sampling circuit 7, a voltage comparison circuit 8 and an MCU. The voltage sampling circuit 7 includes R31, R32, R33, R46, and R41. A PTC 9 is provided between the front and rear terminals of the first relay 4. The first relay 4 and the second relay 3 are connected to a relay control circuit 10. The relay control circuit 10 includes a diode and a triode. The voltage sampling circuit 7 is electrically connected to the voltage comparison circuit 8, and the voltage comparison circuit 8 and the relay control circuit 10 are electrically connected to the MCU.

[0020] A varistor 11 is provided between the live wire terminal 1 and the neutral wire terminal 2 .

[0021] The voltage comparison circuit 8 is used to sample the voltage between the live wire terminal 1 and the neutral wire terminal 2. The voltage comparison circuit 8 compares the data sampled by the voltage sampling circuit 7 with a preset value and transmits the comparison result to the MCU.

[0022] The voltage comparison circuit 8 is provided with an optical coupler 12 electrically connected to the MCU, and the optical coupler 12 transmits the comparison result of the voltage comparison circuit 8 to the MCU.

[0023] The working principle of this utility model:

[0024] When the circuit is initially powered on, that is, when the live wire terminal 1 and the neutral wire terminal 2 are initially powered on, the second relay 3 is directly energized, and the first relay 4 remains in the open state. After a set time, the relay control circuit 10 controls the energization. In this way, when the circuit is powered on, the PTC 9 is used to supply power to the rectifier bridge 6, thereby preventing the large current generated by the electrolytic capacitor 5 at the moment of power-on from directly burning out the fuse and the rectifier bridge. After the instantaneous large current, subsequent power supply is carried out through the first relay 4.

[0025] During the power-on process of the circuit, the voltage adopting circuit 8 samples the voltage between the live terminal 1 and the neutral terminal 2, and transmits the sampled data to the voltage comparison circuit 8. The voltage comparison circuit 8 compares the sampled data with the preset value through the comparator LM293, and transmits the comparison result to the MCU through the optical coupler PC817. For example, the preset value is set to 300V. When the sampled data is greater than 300V, the MCU will control the second relay 3 to disconnect through the relay control circuit 10, thereby powering the fan and protecting the back-end circuit to avoid burning.

[0026] Finally, it should be noted that the above examples are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art from the present invention should be considered as the protection scope of the present invention.

Claims

1. A circuit with voltage detection dual relays in series and parallel PTC control, characterized in that: The invention comprises a second relay (3), a first relay (4) and a rectifier bridge (6) which are sequentially connected in series between a live wire terminal (1) and a neutral wire terminal (2), a voltage sampling circuit (7), a voltage comparison circuit (8) and an MCU, wherein a PTC (9) is arranged between front and rear terminals of the first relay (4), the first relay (4) and the second relay (3) are connected to a relay control circuit (10), the voltage sampling circuit (7) is electrically connected to the voltage comparison circuit (8), and the voltage comparison circuit (8) and the relay control circuit (10) are electrically connected to the MCU.

2. A circuit with voltage detection dual relays in series and parallel PTC control according to claim 1, characterized in that: A varistor (11) is provided between the live wire terminal (1) and the neutral wire terminal (2).

3. A circuit with voltage detection double relays in series and parallel PTC control according to claim 1, characterized in that: The voltage comparison circuit (8) is used to sample the voltage between the live wire terminal (1) and the neutral wire terminal (2); the voltage comparison circuit (8) compares the data sampled by the voltage sampling circuit (7) with a preset value, and transmits the comparison result to the MCU.

4. A circuit with voltage detection double relays in series and parallel PTC control according to claim 3, characterized in that: The voltage comparison circuit (8) is provided with an optical coupler (12) electrically connected to the MCU, and the optical coupler (12) transmits the comparison result of the voltage comparison circuit (8) to the MCU.

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