Voltage sampling and zero cross detection circuit for electric cooker

Abstract

The utility model discloses a voltage sampling and zero-cross detection circuit for an electric cooker. The voltage sampling and zero-cross detection circuit comprises an ACL input end, an AD output end, a voltage sampling unit and a zero-cross detection unit, the ACL input end is used for being connected with a mains supply to input alternating current, a diode D201 connected in series is arranged at the ACL input end, and the alternating current input through the ACL input end is converted into direct current through the diode D201 and is subjected to voltage reduction; the voltage sampling unit comprises a divider resistor R201A, a divider resistor R201B and a divider resistor R201C; one end of the resistor R201A is connected with the output end of the diode D201 in series, the divider resistor R201B and the divider resistor R201C are sequentially arranged at the other end of the resistor R201A in series, and the other end of the divider resistor R201C is connected with the single chip microcomputer through the AD output end; the zero cross detection unit comprises a comparison resistor R202 and a capacitor C201; one end of the comparison resistor R202 is connected with the output end of the voltage sampling unit, the other end of the comparison resistor R202 is grounded, the capacitor C201 is connected with the comparison resistor R202 in parallel, and the output end of the zero-cross detection unit is connected with the single chip microcomputer through an AD output end.

Description

Technical Field

[0001] The utility model relates to the field of detection circuits, in particular to a voltage sampling and zero-crossing detection circuit for an electric rice cooker. Background Art

[0002] The circuit board of an existing heating rice cooker generally includes a control circuit board and a display circuit board with an operation interface. The display circuit board mainly includes a system main control chip MCU and an operation display control circuit. The control circuit board mainly includes a switch control circuit, a fan switch control circuit, a zero-crossing detection circuit, an inner pot temperature detection circuit, an operating current / voltage sampling circuit, etc. The system main control chip MCU is electrically connected to the circuits of the remaining modules respectively and controls the operations of the remaining modules respectively.

[0003] For example, the patent document with patent number 201620094843.7 discloses a voltage sampling circuit and electrical equipment, which includes a voltage dividing resistor and a sampling resistor connected in series, and a detection control unit. One end of the voltage dividing resistor is connected to the mains, and the other end is connected to the sampling resistor. There is a voltage sampling point between the voltage dividing resistor and the sampling resistor. The voltage sampling point and the end of the sampling resistor not connected to the voltage dividing resistor are connected to the detection control unit. The detection control unit is configured to form a loop for the voltage sampling circuit and perform voltage sampling, or to open the voltage sampling circuit.

[0004] The technical solution of the above patent can be disconnected under the action of the detection control unit when voltage sampling is not required. At this time, no current flows through the sampling resistor, and thus no electric energy is consumed.

[0005] However, the commonly used AC voltage sampling circuit is separated from the zero-crossing detection circuit. This not only occupies the system's main control chip MCU resources, but also makes the voltage change easily affected by power interference from the power transmission process, making it impossible to achieve accurate power control.

[0006] Therefore, it is necessary to improve such a structure to overcome the above-mentioned defects. Utility Model Content

[0007] The purpose of the utility model is to provide a voltage sampling and zero-crossing detection circuit for an electric rice cooker to solve the problems existing in the prior art.

[0008] The above technical objectives of the present invention are achieved through the following technical solutions:

[0009] A voltage sampling and zero-crossing detection circuit for an electric rice cooker comprises an ACL input terminal, an AD output terminal, and a voltage sampling unit and a zero-crossing detection unit arranged between the ACL input terminal and the AD output terminal;

[0010] The ACL input terminal is used to connect to the mains to input AC power. A diode D201 is provided in series at the ACL input terminal. The AC power inputted through the ACL input terminal is converted into DC power and its voltage is reduced by the diode D201.

[0011] The voltage sampling unit includes voltage dividing resistors R201A, R201B and R201C;

[0012] One end of the resistor R201A is connected in series with the output end of the diode D201, and the voltage divider resistors R201B and R201C are sequentially connected in series with each other at the other end of the resistor R201A, and the other end of the voltage divider resistor R201C is connected to the single chip microcomputer through the AD output end;

[0013] The zero-crossing detection unit includes a comparison resistor R202 and a capacitor C201;

[0014] One end of the comparison resistor R202 is connected to the output end of the voltage sampling unit, and the other end of the comparison resistor R202 is grounded. The capacitor C201 is connected in parallel with the comparison resistor R202. The output end of the zero-crossing detection unit is connected to the microcontroller through the AD output end.

[0015] Furthermore, the ACL end is connected to the live wire of the mains power supply, and is used to introduce alternating current.

[0016] Furthermore, the diode D201 converts AC into DC through a half-wave rectification structure; in the positive half cycle of AC, the diode is turned on and AC passes through the diode D201; in the negative half cycle of AC, the diode is turned off and current cannot pass through the diode D201.

[0017] Furthermore, the diode D201 is used to perform a primary voltage reduction on the input AC power, and the voltage divider resistors R201A, R201B and R201C are used to perform a secondary voltage reduction on the converted DC power.

[0018] In summary, the present invention has the following beneficial effects:

[0019] The input AC power is converted into DC power and stepped down once by a diode, and then stepped down twice by a voltage divider resistor, thereby reducing the high voltage power to the input low voltage range of the microcontroller for easy processing, thereby reducing errors in sampling and subsequent voltage measurements and ensuring the accuracy of the measurement results.

[0020] The voltage sampling and zero-crossing detection circuits share an AD port of the single-chip microcomputer, which can detect the mains voltage and the zero-crossing signal at the same time, thereby reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1It is a schematic diagram of the voltage sampling and zero-crossing detection circuit described in the utility model. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below with reference to illustrations and specific embodiments.

[0023] like Figure 1 As shown, a voltage sampling and zero-crossing detection circuit for an electric rice cooker proposed by the utility model includes an ACL input, an AD output, and a voltage sampling unit and a zero-crossing detection unit arranged between the ACL input and the AD output;

[0024] The ACL input terminal is used to connect to the mains to input AC power. A diode D201 is provided in series at the ACL input terminal. The AC power inputted through the ACL input terminal is converted into DC power and its voltage is reduced by the diode D201.

[0025] The voltage sampling unit includes voltage dividing resistors R201A, R201B and R201C;

[0026] One end of the resistor R201A is connected in series with the output end of the diode D201, and the voltage divider resistors R201B and R201C are sequentially connected in series with each other at the other end of the resistor R201A, and the other end of the voltage divider resistor R201C is connected to the single chip microcomputer through the AD output end;

[0027] The zero-crossing detection unit includes a comparison resistor R202 and a capacitor C201;

[0028] One end of the comparison resistor R202 is connected to the output end of the voltage sampling unit, and the other end of the comparison resistor R202 is grounded. The capacitor C201 is connected in parallel with the comparison resistor R202. The output end of the zero-crossing detection unit is connected to the microcontroller through the AD output end.

[0029] The ACL end is connected to the live wire of the mains power supply and is used to introduce alternating current.

[0030] The diode D201 converts AC power into DC power through a half-wave rectification structure; in the positive half cycle of AC power, the diode is turned on and AC power passes through the diode D201; in the negative half cycle of AC power, the diode is turned off and current cannot pass through the diode D201.

[0031] The diode D201 is used to perform a primary voltage reduction on the input AC power, and the voltage divider resistors R201A, R201B and R201C are used to perform a secondary voltage reduction on the converted DC power.

[0032] The working principle of this utility model is as follows:

[0033] The input AC power is converted into DC power and stepped down once by a diode, and then stepped down twice by a voltage divider resistor, thereby reducing the high voltage power to the input low voltage range of the microcontroller for easy processing, thereby reducing errors in sampling and subsequent voltage measurements and ensuring the accuracy of the measurement results.

[0034] The voltage sampling and zero-crossing detection circuits share an AD port of the single-chip microcomputer, which can detect the mains voltage and the zero-crossing signal at the same time, thereby reducing costs.

[0035] In this document, the directions or positional relationships indicated by terms such as "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "vertical", and "horizontal" are based on the directions or positional relationships shown in the accompanying drawings and are only for the clarity of the technical solution and the convenience of description. Therefore, they should not be understood as limitations on the present invention.

[0036] As used herein, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion of elements other than the listed elements and may also include additional elements not specifically listed.

[0037] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements are possible without departing from the spirit and scope of the present invention. Such changes and improvements are intended to fall within the scope of the present invention. The scope of protection claimed in this invention is defined by the appended claims and their equivalents.

Claims

1. A voltage sampling and zero-crossing detection circuit for an electric rice cooker, comprising an ACL input, an AD output, and a voltage sampling unit and a zero-crossing detection unit arranged between the ACL input and the AD output; It is characterized in that The ACL input terminal is used to connect to the mains to input AC power. A diode D201 is provided in series at the ACL input terminal. The AC power inputted through the ACL input terminal is converted into DC power and its voltage is reduced by the diode D201. The voltage sampling unit includes voltage dividing resistors R201A, R201B and R201C; One end of the resistor R201A is connected in series with the output end of the diode D201, and the voltage divider resistors R201B and R201C are sequentially connected in series with each other at the other end of the resistor R201A, and the other end of the voltage divider resistor R201C is connected to the single chip microcomputer through the AD output end; The zero-crossing detection unit includes a comparison resistor R202 and a capacitor C201; One end of the comparison resistor R202 is connected to the output end of the voltage sampling unit, and the other end of the comparison resistor R202 is grounded. The capacitor C201 is connected in parallel with the comparison resistor R202. The output end of the zero-crossing detection unit is connected to the microcontroller through the AD output end.

2. The voltage sampling and zero-crossing detection circuit for an electric cooker according to claim 1, wherein The ACL end is connected to the live wire of the mains power supply and is used to introduce alternating current.

3. The voltage sampling and zero-crossing detection circuit for an electric rice cooker according to claim 1, wherein The diode D201 converts AC power into DC power through a half-wave rectification structure; in the positive half cycle of AC power, the diode is turned on and AC power passes through the diode D201; in the negative half cycle of AC power, the diode is turned off and current cannot pass through the diode D201.

4. The voltage sampling and zero-crossing detection circuit for an electric rice cooker according to claim 1, wherein The diode D201 is used to perform a primary voltage reduction on the input AC power, and the voltage divider resistors R201A, R201B and R201C are used to perform a secondary voltage reduction on the converted DC power.

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