Electric heating control circuit compatible with multiple power grids

Abstract

The electric heating control circuit comprises a master control MCU, a zero-crossing circuit, a voltage detection circuit, a driving circuit and a heating load, the input end of the zero-crossing circuit is electrically connected with a current power grid to detect the frequency of the current power grid, the output end of the zero-crossing circuit is electrically connected with a first pin of the master control MCU, and the output end of the zero-crossing circuit is electrically connected with a second pin of the master control MCU. An external interruption trigger circuit is arranged at the first pin to record the number of times of triggering within 1s, and the master control MCU judges the frequency of the current power grid according to the number of times of triggering within 1s; the input end of the voltage detection circuit is electrically connected with a current power grid to detect the voltage of the current power grid, the output end of the voltage detection circuit is electrically connected with a second pin of the master control MCU, and the second pin is provided with an analog input circuit and an ADC detection circuit to convert an analog voltage value of the power grid into a digital value. And the main control MCU judges the voltage of the current power grid according to the obtained digital value.

Description

Technical Field

[0001] The utility model relates to the technical field of electric heating control circuits, in particular to an electric heating control circuit capable of being compatible with multiple power grids. Background Art

[0002] Existing electric heating appliances generally can only be applicable to one specification of power grid, such as one of 220V / 50hz and 120V / 60hz. If an electric heating electrical appliance of 120V / 60hz is connected to a 220V / 50hz power supply, it will cause the power to be abnormally high, and in severe cases, it may cause the heating plate to burn out. Content of the Utility Model

[0003] The purpose of the utility model is to solve at least one of the technical problems existing in the prior art, and to provide an electric heating control circuit capable of being compatible with multiple power grids.

[0004] The electric heating control circuit capable of being compatible with multiple power grids according to the embodiment of the utility model includes a main control MCU, a zero-crossing circuit, a voltage detection circuit, a drive circuit and a heating load. The input end of the zero-crossing circuit is electrically connected to the current power grid to detect the frequency of the current power grid. The output end of the zero-crossing circuit is electrically connected to the first pin of the main control MCU, and an external interrupt trigger circuit is arranged at the first pin to record the number of triggers within 1s. The main control MCU judges the frequency of the current power grid according to the number of triggers within 1s. The input end of the voltage detection circuit is electrically connected to the current power grid to detect the voltage of the current power grid. The output end of the voltage detection circuit is electrically connected to the second pin of the main control MCU, and an analog input circuit and an ADC detection circuit are arranged at the second pin to convert the analog voltage value of the power grid into a digital value. The main control MCU judges the voltage of the current power grid according to the obtained digital value. The input end of the drive circuit is electrically connected to the main control MCU, and the output end of the drive circuit is electrically connected to the heating load. The main control MCU adjusts the current of the drive circuit according to the frequency and voltage of the current power grid to control the heating load to output a constant power to avoid damage to the heating load.

[0005] The electric heating control circuit capable of being compatible with multiple power grids according to the embodiments of the present utility model has at least the following beneficial effects: The power grid transmits parameters such as the power grid frequency and phase angle to the first pin of the main control MCU in the form of pulses through a zero-crossing circuit. The main control MCU records the number of triggers within 1 s through the external interrupt trigger circuit at the first pin. The main control MCU can judge the current power grid frequency according to the number of triggers within 1 s. At the same time, the main control MCU converts the analog voltage value of the power grid into a digital value through the analog input circuit and the ADC detection circuit at the second pin. The main control MCU can judge the current power grid voltage according to the obtained digital value. Then, the main control MCU adjusts the current of the drive circuit according to the current power grid frequency and voltage to control the heating load to output a constant power to avoid damage to the heating load. It can make the electric heating product compatible with multiple power grid specifications, have the same heating performance in different power grid environments, and prevent the heating element from being damaged due to different power grids.

[0006] Additional aspects and advantages of the present utility model will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present utility model. Description of the Drawings

[0007] The following further describes the specific embodiments of the present utility model with reference to the drawings;

[0008] Figure 1 is a structural diagram of an electric heating control circuit capable of being compatible with multiple power grids;

[0009] Figure 2 is a schematic diagram of an electric heating control circuit capable of being compatible with multiple power grids. Specific Embodiments

[0010] This part will describe in detail the specific embodiments of the present utility model. The preferred embodiments of the present utility model are shown in the drawings. The function of the drawings is to supplement the description of the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present utility model. However, it should not be construed as a limitation on the protection scope of the present utility model.

[0011] In the description of the present utility model, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the present utility model.

[0012] In the description of the present utility model, the meaning of "a number of" is one or more, the meaning of "a plurality of" is two or more, and understandings such as "greater than", "less than", "exceeding", etc. do not include the base number, and understandings such as "above", "below", "within", etc. include the base number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0013] Referring to Figure 1 and Figure 2 , a kind of electric heating control circuit of the present utility model that can be compatible with multiple power grids includes a main control MCU, a zero-crossing circuit 11, a voltage detection circuit 12, a drive circuit 13 and a heating load. The input end of the zero-crossing circuit 11 is electrically connected to the current power grid to detect the frequency of the current power grid. The output end of the zero-crossing circuit 11 is electrically connected to the first pin of the main control MCU. An external interrupt trigger circuit is arranged at the first pin to record the number of triggers within 1 s. The main control MCU judges the frequency of the current power grid according to the number of triggers within 1 s. The input end of the voltage detection circuit 12 is electrically connected to the current power grid to detect the voltage of the current power grid. The output end of the voltage detection circuit 12 is electrically connected to the second pin of the main control MCU. An analog input circuit and an ADC detection circuit are arranged at the second pin to convert the analog voltage value of the power grid into a digital value. The main control MCU judges the voltage of the current power grid according to the obtained digital value. The input end of the drive circuit 13 is electrically connected to the main control MCU, and the output end of the drive circuit 13 is electrically connected to the heating load. The main control MCU adjusts the current of the drive circuit 13 according to the frequency and voltage of the current power grid to control the heating load to output a constant power to avoid damage to the heating load. The main control MCU, the zero-crossing circuit 11 and the voltage detection circuit 12 are all prior arts. The zero-crossing circuit 11 is often used to measure parameters such as the zero point of the AC power supply, the power supply frequency and the relevant phase angle, etc. That is, the power grid transmits parameters such as the power grid frequency and phase angle to the first pin of the main control MCU in the form of pulses through the zero-crossing circuit 11. The main control MCU records the number of triggers within 1 s through the external interrupt trigger circuit at the first pin. The main control MCU can judge the frequency of the current power grid according to the number of triggers within 1 s.

[0014] At the same time, the main control MCU converts the analog voltage value of the power grid into a digital value through the analog input circuit and the ADC detection circuit at the second pin. The main control MCU can judge the voltage of the current power grid according to the obtained digital value. Then the main control MCU adjusts the current of the drive circuit 13 according to the frequency and voltage of the current power grid to control the heating load to output a constant power to avoid damage to the heating load. It can make the electric heating product compatible with multiple power grid specifications, have the same heating performance in different power grid environments, and will not cause damage to the heating element due to different power grids.

[0015] Further, the external interrupt trigger circuit is a double-edge trigger circuit, which can trigger an interrupt at both the rising edge and the falling edge of the external signal pin. Generally, the single-edge trigger mode only triggers an interrupt at the rising edge or the falling edge of the signal pin, while the double-edge trigger mode can trigger an interrupt at both edges. Using the external interrupt double-edge trigger can more flexibly monitor the changes of external events. When the level of the external signal pin changes, whether from low level to high level or from high level to low level, an interrupt will be triggered. This is very useful for some applications that need to respond to external events in real time, such as the key detection of input devices and the acquisition of sensor data.

[0016] For example Figure 2 , in some embodiments, the zero-crossing circuit 11 includes a diode D1, a triode Q1, a resistor R1, a resistor R2, a resistor R3 and a capacitor C1. The anode of the diode D1 is electrically connected to the power grid. The cathode of the diode D1 is electrically connected to the base of the triode Q1 and one end of the capacitor C1 respectively through the series-connected resistor R1. The emitter of the triode Q1 and the other end of the capacitor C1 are grounded respectively. The collector of the triode Q1 is electrically connected to one end of the resistor R2 and one end of the resistor R3 respectively. The other end of the resistor R2 is connected to the working voltage. The other end of the resistor R3 is electrically connected to the first pin of the main control MCU. The voltage detection circuit 12 includes a diode D2, a resistor R4, a resistor R5, a resistor R6, a capacitor C2 and a capacitor C3. The anode of the diode D2 is electrically connected to the power grid. The cathode of the diode D2 is electrically connected to one end of the resistor R4, one end of the resistor R5, one end of the resistor R6 and one end of the capacitor C2 respectively through the series-connected resistor R4. The other end of the resistor R5 is connected to one end of the capacitor C3 and the second pin of the main control MCU respectively. The other end of the capacitor C3 is grounded together with the other end of the capacitor C2 and the other end of the resistor R6. The drive circuit 13 includes a bidirectional trigger triode TR1, a triode Q2, a resistor R7, a resistor R8 and a resistor R9. The first end of the bidirectional trigger triode TR1 is electrically connected to the power grid. The second end of the bidirectional trigger triode TR1 is electrically connected to one end of the resistor R7 and one end of the resistor R8 respectively. The other end of the resistor R7 is grounded. The other end of the resistor R8 is electrically connected to the collector of the triode Q2. The emitter of the triode Q2 is connected to the 5V voltage. The base of the triode Q2 is electrically connected to the main control MCU through the series-connected resistor R9. The third end of the bidirectional trigger triode TR1 is electrically connected to the heating load.

[0017] In some embodiments, a thermocouple circuit 14 is further included. The thermocouple circuit 14 is electrically connected to the main control MCU to detect the temperature of the heating load. Further, a display circuit 15 is further included. The display circuit 15 is electrically connected to the main control MCU to display the current temperature and electrical parameters, facilitating the user to observe intuitively.

[0018] Further, an alarm circuit 16 is further included. The alarm circuit 16 is electrically connected to the main control MCU. When the thermocouple circuit 14 detects that the temperature of the heating load exceeds the standard, the main control MCU controls the alarm circuit 16 to send out an alarm message to facilitate prompting the user.

[0019] Further, a power supply circuit 17 is further included. The power supply circuit 17 is electrically connected to the power grid to convert the grid voltage into a DC working voltage, such as 5V DC voltage, to supply power to the above-mentioned multiple circuit modules.

[0020] It is easy for those skilled in the art to understand that on the premise of no conflict, the above preferred modes can be freely combined and superimposed.

[0021] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. All equivalent structural transformations made by using the content of the specification and drawings of the present invention under the inventive concept of the present invention, or directly or indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An electric heating control circuit compatible with multiple power grids, characterized in that: include: A main control MCU, a zero-crossing circuit (11), a voltage detection circuit (12), a drive circuit (13) and a heating load, wherein the input end of the zero-crossing circuit (11) is electrically connected to a current power grid to detect the frequency of the current power grid, the output end of the zero-crossing circuit (11) is electrically connected to a first pin of the main control MCU, an external interrupt trigger circuit is provided at the first pin to record the number of triggers within 1 second, and the main control MCU determines the frequency of the current power grid according to the number of triggers within 1 second; The input end of the voltage detection circuit (12) is electrically connected to the current power grid to detect the voltage of the current power grid, and the output end of the voltage detection circuit (12) is electrically connected to the second pin of the main control MCU, and the second pin is provided with an analog input circuit and an ADC detection circuit to convert the analog voltage value of the power grid into a digital value, and the main control MCU determines the voltage of the current power grid according to the obtained digital value; The input end of the drive circuit (13) is electrically connected to the main control MCU, and the output end of the drive circuit (13) is electrically connected to the heating load. The main control MCU adjusts the current of the drive circuit (13) according to the frequency and voltage of the current power grid to control the heating load to output a constant power to avoid damage to the heating load.

2. The electric heating control circuit capable of being compatible with multiple power grids according to claim 1, characterized in that: The external interrupt trigger circuit is a double-edge trigger circuit.

3. The electric heating control circuit capable of being compatible with multiple power grids according to claim 1, characterized in that: The zero-crossing circuit (11) comprises a diode D1, a transistor Q1, a resistor R1, a resistor R2, a resistor R3 and a capacitor C1, wherein the anode of the diode D1 is electrically connected to the power grid, the cathode of the diode D1 is electrically connected to the base of the transistor Q1 and one end of the capacitor C1 via the series resistor R1, the emitter of the transistor Q1 and the other end of the capacitor C1 are respectively grounded, the collector of the transistor Q1 is electrically connected to one end of the resistor R2 and one end of the resistor R3, the other end of the resistor R2 is connected to the working voltage, and the other end of the resistor R3 is electrically connected to the first pin of the main control MCU.

4. The electric heating control circuit compatible with multiple power grids according to claim 1, characterized in that: The voltage detection circuit (12) comprises a diode D2, a resistor R4, a resistor R5, a resistor R6, a capacitor C2 and a capacitor C3, wherein the anode of the diode D2 is electrically connected to the power grid, the cathode of the diode D2 is electrically connected to one end of the resistor R5, one end of the resistor R6 and one end of the capacitor C2 respectively via the series resistor R4, the other end of the resistor R5 is respectively connected to one end of the capacitor C3 and the second pin of the main control MCU, and the other end of the capacitor C3 is respectively connected to the other end of the capacitor C2 and the other end of the resistor R6 and is grounded.

5. The electric heating control circuit capable of being compatible with multiple power grids according to claim 1, characterized in that: The driving circuit (13) comprises a bidirectional trigger transistor TR1, a transistor Q2, a resistor R7, a resistor R8 and a resistor R9, wherein the first end of the bidirectional trigger transistor TR1 is electrically connected to the power grid, the second end of the bidirectional trigger transistor TR1 is electrically connected to one end of the resistor R7 and one end of the resistor R8 respectively, the other end of the resistor R7 is grounded, the other end of the resistor R8 is electrically connected to the collector of the transistor Q2, the emitter of the transistor Q2 is connected to a 5V voltage, the base of the transistor Q2 is electrically connected to the main control MCU via the series resistor R9, and the third end of the bidirectional trigger transistor TR1 is electrically connected to the heating load.

6. The electric heating control circuit capable of being compatible with multiple power grids according to claim 1, characterized in that: It also includes a thermocouple circuit (14), which is electrically connected to the main control MCU to detect the temperature of the heating load.

7. The electric heating control circuit capable of being compatible with multiple power grids according to claim 6, characterized in that: It also includes a display circuit (15), which is electrically connected to the main control MCU to display the current temperature and electrical parameters.

8. The electric heating control circuit capable of being compatible with multiple power grids according to claim 6, characterized in that: It also includes an alarm circuit (16), which is electrically connected to a main control MCU. When the thermocouple circuit (14) detects that the temperature of the heating load exceeds a standard, the main control MCU controls the alarm circuit (16) to issue an alarm message.

9. The electric heating control circuit capable of being compatible with multiple power grids according to claim 1, characterized in that: It also includes a power supply circuit (17), wherein the power supply circuit (17) is electrically connected to the power grid to convert the power grid voltage into a DC working voltage.

Images