CN114980390A

CN114980390A - Heating detection circuit

Info

Publication number: CN114980390A
Application number: CN202110215237.1A
Authority: CN
Inventors: 左远洋
Original assignee: Midea Group Co Ltd; Guangdong Midea White Goods Technology Innovation Center Co Ltd
Current assignee: Midea Group Co Ltd; Guangdong Midea White Goods Technology Innovation Center Co Ltd
Priority date: 2021-02-25
Filing date: 2021-02-25
Publication date: 2022-08-30

Abstract

The application discloses heating detection circuitry includes: the heating circuit comprises a first power supply circuit, a first selection circuit, a sampling circuit and a first number of heating elements, wherein the first number is an integer greater than or equal to 1; the first selection circuit is connected with the first heating elements and is used for selecting one heating element to be connected with the first power supply circuit and the sampling circuit in series to form a detection loop, and the sampling circuit is used for outputting a detection signal to detect the impedance of the heating elements in the detection loop. By the mode, the number of elements in the heating detection circuit can be reduced.

Description

Heating detection circuit

Technical Field

The present application relates to the field of electronic technology, and more particularly, to a heating detection circuit.

Background

Before the induction cooker is started to heat, whether a cooker is arranged on a coil for heating needs to be detected, and if the coil is not provided with a cooker and is started to heat, a large amount of electromagnetic radiation is generated. At present, for the detection of cookware of a multi-coil induction cooker, each coil needs a complete or partial detection circuit, so that the total number of components of the detection circuit of the whole product is large.

Disclosure of Invention

A first aspect of an embodiment of the present application provides a heating detection circuit, including: the circuit comprises a first power supply circuit, a first selection circuit, a sampling circuit and a first number of heating elements, wherein the first number is an integer greater than or equal to 1; the first selection circuit is connected with the first number of heating elements and is used for selecting one heating element to be connected with the first power supply circuit and the sampling circuit in series to form a detection loop; the sampling circuit is used for outputting a detection signal to detect the impedance of the heating element in the detection loop.

The sampling circuit comprises a sampling resistor, the first end of the sampling resistor is grounded, the second end of the sampling resistor and the first end of each heating element are connected with a common end to realize that the sampling circuit is connected with each heating element, the second end of each heating element is connected with a selection circuit, and the electric signal of the second end of the sampling resistor is used as a detection signal.

The sampling circuit further comprises a compensation capacitor, and the second end of the sampling resistor is connected with the common end through the compensation capacitor.

The first selection circuit comprises a first number of first switches, wherein the first end of each first switch is connected with a corresponding heating element, and the second end of each first switch is connected with a first power supply circuit; and/or the first selection circuit selects each heating element to be connected in series with the first power supply circuit and the sampling circuit in time series.

The first power circuit is a half-bridge inverter circuit and comprises a first MOS tube and a second MOS tube, a drain electrode of the first MOS tube is connected with a first power supply, a source electrode of the first MOS tube is respectively connected with a drain electrode of the second MOS tube and a first selection circuit, and a source electrode of the second MOS tube is grounded.

The heating detection circuit further comprises a second power supply circuit and a first number of second selection circuits, each heating element is connected with the first selection circuit through one corresponding second selection circuit, the second selection circuits are used for selecting the second power supply circuit to form a heating loop with the corresponding heating element, or selecting the first selection circuit to be communicated with the corresponding heating element to form a detection loop, and the second power supply circuit supplies power to the heating elements through the heating loops to achieve heating.

The second selection circuit is a second switch, a first end of the second switch is connected with the corresponding heating element, a second end of the second switch is connected with the second power supply circuit, and a third end of the second switch is connected with the first selection circuit.

The heating detection circuit further comprises a first number of resonant capacitor circuits, each resonant capacitor circuit is connected with a corresponding heating element, the resonant capacitor circuits are connected with the second power supply circuit, so that the resonant capacitor circuits participate in the heating loop, and the heating elements are connected with the sampling circuit through the resonant capacitor circuits.

The resonant capacitor circuit comprises a first resonant capacitor and a second resonant capacitor, the first end of the first resonant capacitor is connected with the first end of the second power circuit, the second end of the first resonant capacitor is connected with the first end of the second resonant capacitor and the heating element respectively, and the second end of the second resonant capacitor is connected with the second end of the second power circuit and the sampling circuit respectively.

The second power supply circuit comprises a first IGBT and a second IGBT, wherein a collector of the first IGBT is used as a first end of the second power supply circuit to be connected with a second power supply, an emitter of the first IGBT is connected with a collector of a second IGBT, a third end of the first IGBT, which is used as the second power supply circuit, is connected with a second selection circuit, and an emitter of the second IGBT is used as a second end of the second power supply circuit; and/or the second end of the second power supply circuit and the sampling circuit are connected with a common end.

The output frequency of the first power supply circuit is larger than the second number times of the output frequency of the second power supply circuit, and the second number is larger than 1.

The beneficial effect of this application is: in contrast to the state of the art, the present application provides a heating detection circuit comprising: the heating circuit comprises a first power supply circuit, a first selection circuit, a sampling circuit and a first number of heating elements, wherein the first number is an integer greater than or equal to 1; the first selection circuit is connected with a first number of heating elements and is used for selecting one of the heating elements to be connected with the first power supply circuit and the sampling circuit in series to form a detection circuit, and the sampling circuit is used for outputting a detection signal to detect the impedance of the heating element in the detection circuit.

Drawings

In order to more clearly illustrate the technical solutions in the present application, the drawings required in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive labor. Wherein:

FIG. 1 is a block diagram illustrating a first embodiment of a heating detection circuit provided herein;

FIG. 2 is another schematic diagram of a first embodiment of a heating detection circuit provided herein;

FIG. 3 is a block diagram of a second embodiment of a heating detection circuit provided herein;

FIG. 4 is another schematic diagram of a second embodiment of a heating detection circuit provided herein;

FIG. 5 is a block diagram illustrating a third embodiment of a heating detection circuit provided herein;

FIG. 6 is another schematic diagram of a third embodiment of a heating detection circuit according to the present application;

FIG. 7 is a block diagram illustrating a fourth embodiment of a heating detection circuit according to the present application;

fig. 8 is another schematic structural diagram of a fourth embodiment of a heating detection circuit provided in the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terms "first" and "second" in this application are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless explicitly specifically limited otherwise. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

Referring to fig. 1, fig. 1 is a schematic block diagram of a first embodiment of a heating detection circuit provided in the present application, and fig. 2 is another schematic structural diagram of the first embodiment of the heating detection circuit provided in the present application.

As shown in fig. 1, in the embodiment of the present disclosure, the heating detection circuit includes: the heating element detection circuit comprises a first power supply circuit 11, a first number (n) of heating elements 12, a first selection circuit 13 and a sampling circuit 14, wherein the first selection circuit 13 is connected with the first number of heating elements 12 and is used for selecting one of the heating elements 12 to be connected with the first power supply circuit 11 and the sampling circuit 14 in series to form a detection loop, and the sampling circuit 14 is used for outputting a detection signal to detect the impedance of the heating element 12 in the detection loop.

As shown in fig. 2, the first power circuit 11 is connected to a first power source for supplying power to the detection circuit. Alternatively, the first power circuit 11 may provide an ac power to the detection circuit to output a high frequency square wave signal. In some embodiments, the first power circuit 11 may be a half-bridge inverter circuit, and includes a first MOS transistor and a second MOS transistor, wherein a drain of the first MOS transistor is connected to the first power source, a source of the first MOS transistor is connected to a drain of the second MOS transistor and the first selection circuit 13, respectively, and a source of the second MOS transistor is grounded. The first power circuit 11 is a half-bridge inverter circuit, and only needs to participate in one resonant circuit during detection. In other embodiments, the first power supply circuit 11 may include two capacitors.

Among them, the MOS transistor is called a Metal Oxide Semiconductor field effect transistor (Metal Oxide Semiconductor), and belongs to an insulated gate type in the field effect transistor, and therefore, the MOS transistor is sometimes called an insulated gate field effect transistor. Compared with a common bipolar transistor, the MOS transistor has the advantages of high input impedance, low noise, large dynamic range, low power consumption, easy integration and the like. The MOS tube can comprise an N-type MOS tube (NMOS) and a P-type MOS tube (PMOS). In some embodiments, the first MOS transistor and the second MOS transistor may be N-type MOS transistors, and in other embodiments, the first MOS transistor and the second MOS transistor may be P-type MOS transistors, which is not limited herein.

As shown in fig. 2, the first power circuit 11 includes a first NMOS transistor and a second NMOS transistor, wherein a drain (D pole) of the first NMOS transistor is connected to the first power Vcc, a source (S pole) of the first NMOS transistor is respectively connected to a drain (D pole) of the second NMOS transistor and the second end of the first selection circuit 13, and a source (S pole) of the second NMOS transistor is connected to a ground level GND, which is a reference ground level of the detection circuit.

In some embodiments, as shown in fig. 2, an electronic device may include a first number of heating elements 12, a first terminal of each heating element 12 being connected to the common terminal PGND, and a second terminal of each heating element 12 being connected to a first terminal of the first selection circuit 13.

The heating detection circuit is used for detecting whether a device (such as a pot) to be heated is on the first number of heating elements 12, and if the device to be heated is detected on the heating elements 12, the electronic equipment starts heating. Wherein the first number is an integer greater than or equal to 1, e.g., 2, 5, 10. The heating element 12 may include, but is not limited to, at least one of: coil, drum, electric heat line, electric heat plate, electric heat stick, electric heat piece. Alternatively, the heating element 12 may comprise one or more coils. In some embodiments, if the heating element 12 comprises a plurality of coils, the plurality of coils may be connected in series.

The first selection circuit 13 is connected to a first number of heating elements 12 for selecting one of the heating elements 12 to be connected in series with the first power supply circuit 11 and the sampling circuit 14 to form a detection loop.

In some embodiments, the first selection circuit 13 may include a first number of first switches, a first terminal of each first switch is connected to a corresponding one of the heating elements 12, and a second terminal of each first switch is connected to the first power circuit 11. Specifically, the first selection circuit 13 may be a multi-way electronic switch (e.g., TMUX1208 of TI), which may include a first number of first switches. The multi-way electronic switch can be an integrated circuit, and one of the heating elements 12 is selected by inputting a control signal to be connected with the first power supply circuit 11 and the sampling circuit 14 in series to form a detection loop.

In some embodiments, the first selection circuit 13 may select each heating element 12 to be connected in series with the first power supply circuit 11 and the sampling circuit 14 in a time-sequential manner, so that a plurality of heating elements 12 may share one sampling circuit 14 at a time. In other embodiments, the first selection circuit 13 may simultaneously select a plurality of heating elements 12 to be connected in series with the first power circuit 11 and the sampling circuit 14 to form a plurality of detection loops.

In a specific implementation scenario, when the induction cooker is not heated, the first selection circuit 13 is turned on, specifically, the first number of first switches may be all closed, wait for the induction cooker to pass through the control signal, sequentially control each first switch to be turned on for a preset time t (e.g., 10 seconds or 1 minute), and after a preset period (e.g., n × t), turn on from the beginning again. And finishing the voltage detection of the sampling resistor R1 in the time of conducting each coil, and judging whether cookware exists.

As shown in fig. 2, the first number is n, the first number of heating elements 12 is n coils (L1-1 to L1-n), and correspondingly, the first selection circuit 13 includes n first switches (S1-1 to S1-n), wherein a first end of each first switch is connected to a corresponding coil, and a second end of each first switch is connected to the first power circuit 11. Specifically, a first end of the first switch S1-1 is connected with the coil L1-1, a first end of the first switch S1-n is connected with the coil L1-n, and second ends of the first switches S1-1 and S1-n are connected between the first NMOS transistor (Q1) and the second NMOS transistor (Q2).

In the disclosed embodiment, the sampling circuit 14 is used to output a detection signal to detect the impedance of the heating element 12 in the detection loop. Alternatively, the detection signal may be a current signal or a voltage signal. In some embodiments, the magnitude of the impedance of the heating element 12 of the electronic device may be determined based on the magnitude of the detected current or the detected voltage across the resistor; based on the determined impedance, it is determined whether a device to be heated is present on the electronic device. In a specific application scenario, the electronic device is an induction cooker, the heating element 12 is a coil, the first power circuit 11 outputs a high-frequency signal, a detection current is formed in a detection loop, and whether a cooking device is provided on the induction cooker is determined by determining the magnitude of the impedance of the coil of the induction cooker and then based on the determined impedance.

In some embodiments, as shown in fig. 2, the sampling circuit 14 may include a sampling resistor R1, a first terminal of the sampling resistor R1 is grounded (connected to a low level GNG), and a second terminal of the sampling resistor R1 is connected to the common terminal PGND, so that the second terminal of the sampling resistor R1 and the first terminal of each heating element 12 are both connected to the common terminal PGND, thereby enabling the sampling circuit 14 to be connected to each heating element 12, and each heating element 12 may share one sampling circuit 14 for detection. It is understood that in the embodiments of the present application, the element or circuit connected to the common terminal PGND may be a direct connection (as in fig. 1) or an indirect connection (as in fig. 2).

Alternatively, a sampling point may be provided at the second terminal of the sampling resistor R1, and the electric signal at the second terminal of the sampling resistor R1 may be used as the detection signal.

In a specific implementation scenario, when a pot is located on the coil, the impedance of the coil changes, so that the impedance of the whole detection loop changes, and thus the voltage across the sampling resistor R1 changes, and therefore, it is possible to determine whether a pot is located on the coil according to the detection signal by detecting the electrical signal at the second end of the sampling resistor R1 as the detection signal.

In some embodiments, as shown in fig. 2, the sampling circuit 14 may further include a compensation capacitor C1, a first terminal of the compensation capacitor C1 is connected to the second terminal of the sampling resistor R1, and a second terminal of the compensation capacitor C1 is connected to the common terminal PGND, so that the second terminal of the sampling resistor R1 may be connected to the common terminal PGND through the compensation capacitor C1. The compensation capacitor C1 is used for adjusting the electrical signal at the second end of the sampling resistor R1 to a normal range of detection conditions.

In some embodiments, the electrical signal is a voltage signal, and the compensation capacitor C1 is used to adjust the voltage across the sampling resistor R1, so that the voltage across the sampling resistor R1 is within a normal range, thereby facilitating the detection of the voltage detection device. In some implementations, the magnitude of Vcc may vary from electronic device to electronic device, and therefore, in order to ensure that the voltage value of the sampling resistor R1 is within the normal range, the compensation capacitor C1 is added for adjustment. Generally, after the resistance value of the sampling resistor R1 is determined, the voltage value output from the second terminal of the sampling resistor R1 can be adjusted to be within the normal range by providing the compensation capacitor C1 with a corresponding capacitance value. It can be understood that, when the electrical signal is a current signal, the compensation capacitor C1 may also adjust the current in the detection loop, so that the current value in the detection loop is within a normal range, thereby facilitating the detection of the current detection device, and details are not described here.

In some embodiments, the heating detection circuit may further comprise a first number of resonant capacitive circuits 15, each resonant capacitive circuit 15 being connected to a corresponding one of the heating elements 12. Specifically, a first end of each resonant capacitor circuit 15 is connected to each heating element 12, and a second end of each resonant capacitor circuit 15 and a second end of the compensation capacitor C1 are connected to the common terminal PGND, so that a detection loop corresponding to each heating element 12 can be formed.

In the disclosed embodiment, the alternating frequency of the heating element 12 in the detection loop can be determined by the resonant capacitive circuit 15, so that the heating element 12 operates at a suitable alternating frequency and so that the heating element 12 has a suitable detection current.

Alternatively, the resonant capacitor circuit 15 may include at least one resonant capacitor.

As shown in fig. 2, the first number is n, the heating detection circuit includes n resonant capacitor circuits 15, wherein the 1 st resonant capacitor circuit 15 includes a resonant capacitor CAP2-1, a first end of the resonant capacitor CAP2-1 is connected to a first end of the coil L1-1, and a second end of the resonant capacitor CAP2-1 is connected to the common terminal PGND, so that the coil L1-1 is connected to the common terminal through the resonant capacitor circuit 15; correspondingly, the nth resonant capacitor circuit 15 comprises a resonant capacitor CAP2-n, the first end of the resonant capacitor CAP2-n is connected with the first end of the coil L1-n, and the second end of the resonant capacitor CAP2-n is connected with the common end PGND, so that the coil L1-n is connected with the common end PGND through the resonant capacitor circuit 15, and since the second end of the resonant capacitor CAP2-1, the second end of the resonant capacitor CAP2-n and the second end of the compensation capacitor C1 are all connected with the common end, a detection loop corresponding to the 1 st coil and the nth coil can be formed, and similarly, detection loops corresponding to other coils (2-n-1 coils) can be formed, and further description is omitted.

In the embodiment of the present disclosure, the sampling circuit 14 includes a sampling resistor R1 and a compensation capacitor C1, wherein the sampling resistor R1 and the compensation capacitor C1 are located between the common terminal PGND and the low level GND, and no other circuit connection exists between the common terminal PGND and the low level GND, so that the sampling resistor R1 can be shared by a plurality of heating elements 12, and the heating elements 12 in each detection loop do not need a separate compensation capacitor C1 and a separate sampling resistor R1, thereby reducing the number of elements in the heating detection circuit.

Above-mentioned scheme provides a heating detection circuitry, includes: the circuit comprises a first power supply circuit, a first selection circuit, a sampling circuit and a first number of heating elements, wherein the first number is an integer greater than or equal to 1; the first selection circuit is connected with a first number of heating elements and is used for selecting one of the heating elements to be connected with the first power supply circuit and the sampling circuit in series to form a detection loop, and the sampling circuit is used for outputting a detection signal to detect the impedance of the heating element in the detection loop.

Furthermore, the ground level is connected to sampling resistor's first end, and sampling resistor's second end passes through compensation capacitance and connects the common port, and from this, only need detect the signal of telecommunication of sampling resistor second end output and can realize treating the detection of heating device (like, the pan) to heating detection circuitry's structure can be simplified.

Further, based on the above structure, the detection circuit can use weak current (i.e. power supply with lower voltage, typically less than 36V, such as 5V), so that the current in the detection circuit is smaller and the generated power is lower.

Referring to fig. 3 to 4, fig. 3 is a schematic block diagram of a second embodiment of a heating detection circuit provided in the present application, and fig. 4 is another schematic structural diagram of the second embodiment of the heating detection circuit provided in the present application.

Unlike the above-described embodiments, in the embodiment of the present disclosure, the first predetermined number is 1, that is, the heating detection circuit includes one heating element 22.

As shown in fig. 3, the heating detection circuit includes: the circuit comprises a first power supply circuit 21, a heating element 22, a first selection circuit 23 and a sampling circuit 24, wherein the first selection circuit 23 is connected with the heating element 22 and is used for being connected with the first power supply circuit 21 and the sampling circuit 24 in series to form a detection loop, and the sampling circuit 24 is used for outputting a detection signal to detect the impedance of the heating element 22 in the detection loop. The first selection circuit 23 may be used to control the connection or disconnection of the detection loop. Specifically, the description of the components and circuits therein can refer to the corresponding positions of the above embodiments, and are not repeated herein.

In some embodiments, as shown in fig. 3 and 4, since the heating detection circuit includes only one heating element 22, the first power supply circuit 21 may be directly connected to the heating element 22 to supply the detection current to the heating element 22, so that it may not be necessary to provide the first selection circuit 23 on the connection line between the heating element 22 and the first power supply to select one of the plurality of heating elements 22, and the first selection circuit 23 may be omitted to reduce the number of elements of the heating detection circuit.

In some embodiments, as shown in fig. 4, the heating detection circuit may further include a resonant capacitor circuit 25, the resonant capacitor circuit 25 being connected to the heating element 22. Specifically, a first terminal of the resonant capacitor circuit 25 is connected to the heating element 22, and a second terminal of the resonant capacitor circuit 25 and a second terminal of the compensation capacitor C1 are both connected to a common terminal, so that a detection loop of the heating element 22 can be formed. Alternatively, the resonant capacitor circuit 25 may include at least one resonant capacitor.

As shown in fig. 4, the resonant capacitor circuit 25 includes a resonant capacitor CAP2, a first end of the resonant capacitor CAP2 is connected to a first end of the coil L1, and a second end of the resonant capacitor CAP2 is connected to the common terminal PGND, so that the coil L1 is connected to the common terminal PGND through the resonant capacitor circuit 25, and a detection loop of the coil L1 can be formed.

With the above arrangement, when the first number is 1 in the first embodiment, the heating detection circuit having only a single heating element is provided, and the number of elements of the heating detection circuit can be reduced due to the reduction of the first selection circuit.

Referring to fig. 5, fig. 5 is a schematic block diagram of a third embodiment of a heating detection circuit provided in the present application, and fig. 6 is another schematic structural diagram of the third embodiment of the heating detection circuit provided in the present application.

In this embodiment, the heating detection circuit includes: the circuit comprises a first power supply circuit 31, a first number of heating elements 32, a first selection circuit 33 and a sampling circuit 34, wherein the first selection circuit 33 is connected with the heating elements 32 and is used for being connected with the first power supply circuit 31 and the sampling circuit 34 in series to form a detection loop, and the sampling circuit 34 is used for outputting a detection signal to detect the impedance of the heating elements 32 in the detection loop. Specifically, the description of the components and circuits therein can refer to the corresponding positions of the above embodiments, and are not repeated herein.

Different from the above embodiment, the heating detection circuit may further include a second power circuit 36 and a first number of second selection circuits 37, wherein each second selection circuit 37 is connected to one heating element 32, each heating element 32 may be selectively connected to the first power circuit 31 or the second power circuit 36 through the second selection circuit 37, when the heating element 32 is selectively connected to the first power circuit 31, the first power circuit 31 is connected to the corresponding heating element 32 to form a detection loop, and when the heating element 32 is selectively connected to the second power circuit 36, the second power circuit 36 and the corresponding heating element 32 form a heating loop.

In some embodiments, when the electronic device detects that the device is to be heated on the heat-removing element or when the electronic device receives a user command, a control signal is output to control the second selection circuit 37 to connect the second power circuit 36 to form a heating circuit for heating operation. When the electronic device is powered on, a control signal is output to control the second selection circuit 37 to connect with the first power circuit 31 to form a heating loop, and heating detection is started.

It will be appreciated that the number of second selection circuits 37 is the same as the number of heating elements 32, so that each heating element 32 is connected to the first power circuit 31 or the second power circuit 36 through a corresponding one of the second selection circuits 37, so that each second selection circuit 37 can be controlled independently, and each heating element 32 can be controlled independently to perform the function of detecting or heating.

It is noted that in the presently disclosed embodiment, the heating detection circuit includes a plurality of heating elements 32 and a plurality of second selection circuits 37.

In some embodiments, a first terminal of second power supply circuit 36 is coupled to a second power supply, and a second terminal of second power supply circuit 36 and sampling circuit 34 are both coupled to a common terminal. Wherein the second power circuit 36 may be used to provide ac power to the heating circuit. The ac power source includes, but is not limited to, one of: sine wave AC power supply, square wave AC power supply.

In one embodiment, the second power source is 220V DC. The 220V dc voltage passes through the second power circuit 36, and then outputs 220V ac voltage.

In another embodiment, the second power source is a 220V ac voltage, and the 220V ac voltage is an ac voltage having only a positive phase voltage (positive half wave). The voltage supplied from the second power supply passes through the second power supply circuit 36, and then an ac voltage having positive and negative phases is output.

In yet another embodiment, the second power supply is a 220V alternating voltage (mains). A rectifying circuit is further provided between the second power supply and the second power supply circuit 36, and the rectifying circuit converts 220V ac voltage into 220V dc voltage; the second power supply circuit 36 converts a 220V dc voltage into a 220V ac voltage.

Alternatively, the second power circuit 36 may include an Insulated Gate Bipolar Transistor (IGBT), where the IGBT is a composite fully-controlled voltage-driven power semiconductor device composed of a BJT (Bipolar Transistor) and an MOS (Insulated Gate field effect Transistor), and has the advantages of both high input impedance of the MOSFET and low on-state voltage drop of the GTR, and is fast in switching speed and high in current-carrying density.

As shown in fig. 6, in some embodiments, the second power circuit 36 may include a first IGBT (IGBT1) and a second IGBT (IGBT2), and the frequency of the on and off of the first IGBT and the second IGBT may be used to adjust the frequency of the signal of the second power source, so that the second power source may be changed into a high-frequency pulse wave by an inverter circuit formed by the first IGBT and the second IGBT to supply power to the heating element.

The collector (C) of the first IGBT is connected to the second power AC220V as the first terminal of the second power circuit 36, the emitter (E) of the first IGBT is connected to the collector (C) of the second IGBT, the third terminal of the second power circuit 36 is connected to the second selection circuit 37, and the emitter (E) of the second IGBT is connected to the common terminal PGND as the second terminal of the second power circuit 36. The common terminal PGND is a reference ground level of the second power supply.

In the disclosed embodiment, the output frequency of the first power supply circuit 31 is greater than a second number times the output frequency of the second power supply circuit 36, the second number being greater than 10. In some embodiments, the first number is greater than 10, so that the output frequency of the first power circuit 31 is much greater than the output frequency of the second power circuit 36, so that the impedance of the compensation capacitor at the heating frequency is much greater than the impedance at the detection frequency, and thus the compensation capacitor can be used to reduce the interference current generated by the interference noise on the detection loop. Since a part of the coil is heating, an interference noise at the heating frequency is generated on the resonant capacitor CAP2 of the unheated coil.

In the embodiment of the present disclosure, the second selection circuit 37 may be used to select the second power circuit 36 to form a heating loop with the corresponding heating element 32, or select the first selection circuit 33 to be connected with the corresponding heating element 32 to form a detection loop, so that the second power circuit 36 may supply power to the heating element 32 through the heating loop to realize heating, or the first power circuit 31 may supply power to the heating element 32 through the detection loop to realize detection.

In some embodiments, the second selection circuit 37 may be a second switch. The second switch is, for example, a single-pole double-throw switch. The first end (1) of the second switch is connected with the corresponding heating element 32, the second end (2) of the second switch is connected with the second power supply circuit 36, and the third end (5) of the second switch is connected with the first selection circuit 33. As shown in fig. 6, the fourth terminal (3) and the fifth terminal (4) of the second switch are used for inputting a control signal, so as to control the second switch to be connected to the second power circuit 36 or the first selection circuit 33.

As shown in FIG. 6, the heating detection circuit comprises n coils (L1-1-L1-n) and n second switches (K1-1-K1-n), wherein a first end of the second switch K1-1 is connected with a second end of the coil L1-1, a second end of the second switch K1-1 is connected with an emitter (E) of the first IGBT and a collector (C) of the second IGBT, and a third end of the second switch K1-1 is connected with a first end of the first switch S1-1; the first end of the second switch K1-n is connected with the second end of the coil L1-n, the second end of the second switch K1-n is connected with the emitter (E) of the first IGBT and the collector (C) of the second IGBT, the third end of the second switch K1-n is connected with the first end of the first switch S1-n, correspondingly, the connection modes of other second switches (K1-2-K1- (n-1)) are similar, and the description is omitted here.

In some embodiments, the heating detection circuit may further include a first number of resonant capacitive circuits 35. Each resonant capacitor circuit 35 is connected to a corresponding one of the heating elements 32 and the resonant capacitor circuit 35 is connected to the second power supply circuit 36 such that the resonant capacitor circuit 35 participates in the heating circuit. Specifically, a first terminal of each resonant capacitor circuit 35 is connected to a first terminal of the second power supply circuit 36, and is commonly connected to the second power supply circuit 36, a second terminal of each resonant capacitor circuit 35 is connected to the common terminal, and a third terminal of each resonant capacitor circuit 35 is connected to a corresponding one of the heating elements 32, so that the heating element 32 can be connected to the sampling circuit 34 through the resonant capacitor circuit 35.

In the disclosed embodiment, the alternating frequency of the heating element 32 in the heating circuit can also be determined by the resonant capacitor circuit 35, so that the heating element 32 operates at a suitable alternating frequency and the heating element 32 has a suitable heating current.

In some embodiments, the resonant capacitor circuit 35 may include a first resonant capacitor CAP1 and a second resonant capacitor CAP 2. A first end of the first resonant capacitor CAP1 is connected to a first end of the second power circuit 36, a second end of the first resonant capacitor CAP1 is connected to a first end of the second resonant capacitor CAP2 and the heating element 32, and a second end of the second resonant capacitor CAP2 is connected to a second end of the second power circuit 36 and the sampling circuit 34.

In the disclosed embodiment, the alternating frequency of the heating element 42 in the heating circuit can be determined by the first resonant capacitor CAP1, so that the heating element 42 operates at a suitable alternating frequency and the heating element 42 has a suitable heating current, and the alternating frequency of the heating element 42 in the detection circuit can be determined by the second resonant capacitor CAP2, so that the heating element 42 operates at a suitable alternating frequency and the heating element 42 has a suitable detection current.

As shown in fig. 6, the heating detection circuit includes n resonant capacitor circuits 35, wherein the 1 st resonant capacitor circuit 35 includes a first resonant capacitor CAP1-1 and a second resonant capacitor CAP2-1, a first end of the first resonant capacitor CAP1-1 and a collector (C) of the first IGBT are both connected to the second power AC220V, a second end of the first resonant capacitor CAP1-1 is respectively connected to a first end of the second resonant capacitor CAP2-1 and a first end of the coil L1-1, a second end of the second resonant capacitor CAP2-1, a second end of the second power circuit 36 and a second end of the sampling circuit 34 are both connected to the common terminal PGND, so that the second end of the second resonant capacitor CAP2-1 is respectively connected to the second end of the second power circuit 36 and the sampling circuit 34; the nth resonant capacitor circuit 35 includes a first resonant capacitor CAP1-n and a second resonant capacitor CAP2-n, wherein a first end of the CAP1-n is connected to the second power AC220V, a second end of the first resonant capacitor CAP1-n is connected to a first end of the second resonant capacitor CAP2-n and a first end of the coil L1-n, and a second end of the second resonant capacitor CAP2-n, a second end of the second power circuit 36 and a second end of the sampling circuit 34 are both connected to the common terminal PGND, so that the second end of the second resonant capacitor CAP22-n is connected to the second end of the second power circuit 36 and the sampling circuit 34, and accordingly, the connection manners of the other resonant capacitor circuits 35 are similar and are not repeated herein.

Above-mentioned scheme, a heating detection circuitry with heating and detection function is provided, this heating detection circuitry includes second power supply circuit and second selection circuit, can select to connect second power supply circuit to realize heating or connect first power supply circuit to realize heating and detect as required through the second selection circuit, secondly, first power supply circuit's output frequency is greater than the second number times of second power supply circuit's output frequency, make the impedance of compensation electric capacity under heating frequency be greater than the impedance under detecting the frequency far away, and then can be used for reducing the interference current that interference noise produced on detecting the return circuit, improve the accuracy that detects.

Referring to fig. 7 to 8, fig. 7 is a schematic block diagram of a fourth embodiment of a heating detection circuit provided in the present application, and fig. 8 is another schematic structural diagram of the fourth embodiment of the heating detection circuit provided in the present application.

In the embodiment of the present disclosure, the heating detection circuit includes: a first power supply circuit 41, a heating element 42 and a sampling circuit 44, the sampling circuit 44 being arranged to output a detection signal for detecting the impedance of the heating element 42 in the detection loop a. Specifically, the description of the components and circuits therein can refer to the corresponding positions of the above embodiments, and are not repeated herein. In some embodiments, the heating detection circuit may further include a first selection circuit, a first end of the first selection circuit is connected to the heating element 42, and a second end of the first selection circuit is connected to the first power circuit 41, for controlling the connection or disconnection of the detection loop a.

Different from the above embodiments, in the embodiment of the present disclosure, the first preset number is 1, that is, the heating detection circuit includes one heating element 42, and correspondingly, the heating detection circuit includes one second selection circuit 47, where the second selection circuit 47 may be used to select the second power circuit 46 to form a heating loop B with the corresponding heating element 42, or select the first selection circuit to form a detection loop a with the corresponding heating element 42, so that the second power circuit 46 may supply power to the heating element 42 through the heating loop B to implement heating, or the first power circuit 41 supplies power to the heating element 42 through the detection loop a to implement detection. Since the electronic apparatus includes only one heating element 42, the first selection circuit for switching the connection of the heating elements 42 can be omitted, and the number of elements of the heating detection circuit can be reduced.

As shown in fig. 7 and 8, the heating detection circuit may further include a resonant capacitor circuit 45, and the resonant capacitor circuit 45 is connected to the heating element 42. Specifically, a first terminal of the resonant capacitor circuit 45 is connected to the heating element 42, and a second terminal of the resonant capacitor circuit 45, a second terminal of the compensation capacitor, and a second terminal of the second power circuit 46 are connected to the common terminal PGND, so that the detection loop a and the heating loop B of the heating element 42 may be formed, respectively. Alternatively, the resonant capacitor circuit 45 may include at least one resonant capacitor.

As shown in fig. 8, the resonant capacitor circuit 45 includes a first resonant capacitor CAP1 and a second resonant capacitor CAP2, wherein a first end of the first resonant capacitor CAP1 and a collector (C) of the first IGBT are both connected to the second power AC220V, a second end of the first resonant capacitor CAP1 is respectively connected to a first end of the second resonant capacitor CAP2 and a first end of the coil L1, and a second end of the second resonant capacitor CAP2, a second end of the second power circuit 46 and a second end of the sampling circuit 44 are both connected to the common terminal PGND, so that the second end of the second resonant capacitor CAP2 is respectively connected to the second end of the second power circuit 46 and the sampling circuit 44, and thus the heating loop B and the detection loop a can be formed respectively.

In the above-mentioned solution, when the first number in the third embodiment is 1, the heating detection circuit having only a single heating element is provided, and the heating detection circuit includes the second power supply circuit and the second selection circuit, the second power supply circuit can be selectively connected to realize heating or the first power supply circuit can be connected to realize heating detection by the second selection circuit as needed, and secondly, since the first selection circuit is reduced, the number of elements of the heating detection circuit can be reduced.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings, or which are directly or indirectly applied to other related technical fields, are intended to be included within the scope of the present application.

Claims

1. A heating detection circuit, comprising: a first power supply circuit, a first selection circuit, a sampling circuit, and a first number of heating elements, wherein the first number is an integer greater than or equal to 1;

the first selection circuit is connected with the first number of heating elements and is used for selecting one heating element to be connected with the first power supply circuit and the sampling circuit in series to form a detection loop; the sampling circuit is used for outputting a detection signal to detect the impedance of the heating element in the detection loop.

2. The circuit of claim 1, wherein the sampling circuit comprises a sampling resistor, a first end of the sampling resistor is grounded, a second end of the sampling resistor and a first end of each heating element are connected to a common terminal to realize the connection of the sampling circuit with each heating element, a second end of each heating element is connected to the selection circuit, and an electric signal of the second end of the sampling resistor is used as the detection signal.

3. The circuit of claim 2, wherein the sampling circuit further comprises a compensation capacitor, and wherein the second terminal of the sampling resistor is connected to the common terminal through the compensation capacitor.

4. The circuit of claim 1, wherein the first selection circuit comprises the first number of first switches, a first terminal of each of the first switches is connected to a corresponding one of the heating elements, and a second terminal of each of the first switches is connected to the first power circuit;

and/or the first selection circuit selects each heating element to be connected in series with the first power supply circuit and the sampling circuit in a time sequence.

5. The circuit of claim 1, wherein the first power circuit is a half-bridge inverter circuit, and comprises a first MOS transistor and a second MOS transistor, a drain of the first MOS transistor is connected to a first power source, a source of the first MOS transistor is connected to a drain of the second MOS transistor and the first selection circuit, respectively, and a source of the second MOS transistor is grounded.

6. The circuit of claim 1, wherein the heating detection circuit further comprises a second power circuit and the first number of second selection circuits, each of the heating elements is connected to the first selection circuit through a corresponding one of the second selection circuits, the second selection circuits are used for selecting the second power circuit to form a heating loop with the corresponding heating element or selecting the first selection circuit to be connected to the corresponding heating element to form the detection loop, and the second power circuit supplies power to the heating element through the heating loop to realize heating.

7. The circuit of claim 6, wherein the second selection circuit is a second switch, a first terminal of the second switch is connected to the corresponding heating element, a second terminal of the second switch is connected to the second power circuit, and a third terminal of the second switch is connected to the first selection circuit.

8. The circuit of claim 6, wherein the heating detection circuit further comprises the first number of resonant capacitor circuits, each resonant capacitor circuit coupled to a corresponding one of the heating elements, and the resonant capacitor circuits coupled to the second power circuit to participate in the heating loop, the heating elements coupled to the sampling circuit through the resonant capacitor circuits.

9. The circuit of claim 8, wherein the resonant capacitor circuit comprises a first resonant capacitor and a second resonant capacitor, a first terminal of the first resonant capacitor is connected to a first terminal of the second power circuit, a second terminal of the first resonant capacitor is connected to a first terminal of the second resonant capacitor and the heating element, respectively, and a second terminal of the second resonant capacitor is connected to a second terminal of the second power circuit and the sampling circuit, respectively.

10. The circuit of claim 6, wherein the second power circuit comprises a first IGBT and a second IGBT, a collector of the first IGBT is connected with a second power source as a first end of the second power circuit, an emitter of the first IGBT is connected with a collector of the second IGBT tube, a third end of the second power circuit is connected with the second selection circuit, and an emitter of the second IGBT is connected with a second end of the second power circuit;

and/or the second end of the second power supply circuit and the sampling circuit are connected with a common end.

11. The circuit of claim 6, wherein the output frequency of the first power supply circuit is greater than a second number of times the output frequency of the second power supply circuit, the second number being greater than 10.