Electromagnetic heating control circuit and electromagnetic heating device

Abstract

The application discloses an electromagnetic heating control circuit and an electromagnetic heating device. The electromagnetic heating control circuit comprises a power supply module, a rectification and filtering module, an instantaneous current detection module, a resonance heating module, a driving power tube, a control module and a driving module. The instantaneous current detection module is used for detecting the instantaneous current of the driving power tube and outputting an electric signal according to the flow direction of the instantaneous current and judging whether the instantaneous current is greater than or equal to a preset voltage threshold. The control module is used for outputting a pulse width modulation signal to the driving module according to the electric signal, so as to adjust the driving pulse width of the driving power tube. The electromagnetic heating control circuit of the application detects the flow direction of the instantaneous current of the driving power tube and judges whether the sampling voltage corresponding to the instantaneous current is greater than or equal to the preset voltage threshold through the instantaneous current detection module, so that the control module outputs the pulse width modulation signal to the driving module to adjust the driving pulse width of the driving power tube, thereby reducing the switching loss of the power tube and improving the reliability.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic heating technology, and in particular to an electromagnetic heating control circuit and an electromagnetic heating device. Background Technology

[0002] An induction cooker is an electric cooking appliance that uses the principle of electromagnetic induction heating. It generates an alternating magnetic field through a high-frequency induction heating coil (i.e., an excitation coil), which induces eddy currents in a metal pot placed on the cooktop, thus heating the food. Induction cookers are widely used due to their advantages such as high efficiency and energy saving, ease of control, and wide applicability.

[0003] Currently, the control technology in electromagnetic heating control circuits can employ a single-tube topology to control the coil heating the cookware. However, when using a single-tube topology in an electromagnetic heating control circuit to heat the cookware with different power levels, the instantaneous conduction current of the driving power transistor (Insulated Gate Bipolar Transistor, IGBT) exhibits various operating conditions.

[0004] When the coil heats the pot with relatively low power, the IGBT exhibits a hard-turn-on phenomenon. That is, the resonant voltage VC formed by the coil connected to the IGBT cannot be reduced to 0V. The IGBT does not resonate to the zero-crossing point, and the IGBT will turn on at a higher voltage. This will cause the instantaneous current of the IGBT to be too large, that is, the IGBT switching loss is too large. The IGBT temperature will rise and it may even break down and be damaged.

[0005] When the coil heats the cookware with relatively high power, the resonant voltage VC formed by the coil connected to the IGBT drops below the reference voltage 0V. At this time, the current in the electromagnetic heating control circuit flows through the diode built into the IGBT, which will also cause the IGBT temperature to rise or even break down and be damaged. Summary of the Invention

[0006] In view of this, the present invention aims to at least partially solve one of the problems in the related art. Therefore, the object of the present invention is to provide an electromagnetic heating control circuit and an electromagnetic heating device.

[0007] This application provides an electromagnetic heating control circuit. The electromagnetic heating control circuit includes: a power supply module, a rectifier and filter module, a transient current detection module, a resonant heating module, a drive power transistor, a control module, and a drive module; the input terminal of the rectifier and filter module is connected to the power supply module, the first output terminal of the rectifier and filter module is connected to the first input terminal of the control module, and the second output terminal of the rectifier and filter module is connected to the first input terminal of the transient current detection module; the second input terminal of the transient current detection module is connected to the first terminal of the resonant heating module, the resonant heating module includes a resonant capacitor and a coil inductor, and the resonant heating module is used to heat a cookware; the second terminal of the resonant heating module is connected to the collector of the drive power transistor; the emitter of the drive power transistor is connected to the emitter of the transient current detection module. The second input terminal is connected; the output terminal of the control module is connected to the input terminal of the drive module, and the gate of the drive power transistor is connected to the output terminal of the drive module; the output terminal of the instantaneous current detection module is connected to the second input terminal of the control module; the power supply module is used to provide electrical energy; the rectification and filtering module is used to filter and rectify the AC signal emitted by the power supply module into a DC signal; the instantaneous current detection module is used to detect the instantaneous current when the drive power transistor is turned on, and outputs an electrical signal based on the direction of the instantaneous current and whether the instantaneous current is greater than or equal to a preset voltage threshold; the control module is used to output a pulse width modulation signal to the drive module based on the electrical signal, so that the drive module adjusts the drive pulse width of the drive power transistor.

[0008] In some embodiments, the instantaneous current detection module includes a voltage acquisition unit, a current direction determination unit, and a current limit determination unit; the first terminal of the voltage acquisition unit is connected to the circuit between the rectifier filter module and the resonant heating module, and the voltage acquisition unit is used to acquire the sampling voltage at the instant the drive power transistor is turned on in real time; the first terminal of the current direction determination unit is connected to the second terminal of the voltage acquisition unit, the second terminal of the current direction determination unit is grounded, and the third terminal of the current direction determination unit is connected to the second input terminal of the control module; the current direction determination unit is used to determine whether the sampling voltage is greater than 0 to determine... The instantaneous current is directed to the direction of flow, and a first electrical signal is output to the control module. The first terminal of the current limit determination unit is connected to the second terminal of the voltage acquisition unit, and the second terminal of the current limit determination unit is connected to the second input terminal of the control module. The current limit determination unit is used to determine whether the sampled voltage corresponding to the instantaneous current is greater than or equal to the preset voltage threshold. If the sampled voltage is determined to be greater than or equal to the preset voltage threshold, a second electrical signal is output to the control module. The control module is used to control the output of a pulse width modulation signal according to the first electrical signal and the second electrical signal to adjust the driving pulse width of the driving power transistor.

[0009] In some implementations, the current direction determination unit is used to determine whether the direction of the instantaneous current is the direction of the hard-on conduction mode based on the sampling voltage being less than 0, and to determine whether the direction of the instantaneous current is the direction of the freewheeling conduction mode based on the sampling voltage being greater than 0.

[0010] In some implementations, the control module first receives a first flip signal from the current direction determination unit, in which the first electrical signal flips from a high level to a low level, and then receives a second flip signal from the current limit determination unit, in which the second electrical signal flips from a high level to a low level. Then, it outputs a first pulse width modulation signal to increase the driving pulse width of the driving power transistor until no second flip signal is received within a preset time interval.

[0011] In some implementations, the control module first receives a second flip signal from the current limiting determination unit, in which the second electrical signal flips from a high level to a low level, and then receives a first flip signal from the current direction determination unit, in which the first electrical signal flips from a high level to a low level. Then, it outputs a second pulse width modulation signal to reduce the driving pulse width of the driving power transistor until no second flip signal is received within a preset time interval.

[0012] In some embodiments, the voltage acquisition unit includes a first capacitor and a first resistor, which are connected in series in the connection circuit between the rectifier filter module and the resonant heating module.

[0013] In some embodiments, the current direction determination unit further includes a first comparator amplifier, the first terminal of which is connected between the first capacitor and the first resistor, the second terminal of which is connected to the second input terminal of the control module, and the third terminal of which is grounded; the first comparator amplifier is used to compare the sampled voltage with the value of 0 to output the first electrical signal; the current limit determination unit includes a second comparator amplifier, the first terminal of which is connected to the connection circuit between the voltage acquisition unit and the first comparator amplifier, the second terminal of which is connected to the second input terminal of the control module, and the third terminal of which is grounded; the second comparator is used to compare the sampled voltage with the value of the preset voltage threshold to output the second electrical signal.

[0014] In some embodiments, the current limit determination unit further includes a first voltage divider resistor and a second voltage divider resistor connected in parallel with the second comparator amplifier. The first voltage divider resistor and the second voltage divider resistor are used to provide a reference voltage for a preset voltage threshold.

[0015] In some embodiments, the electromagnetic heating control circuit further includes a voltage detection module, and the rectifier and filter module further includes a current detection module. Both the voltage detection module and the current detection module are connected to the control module. The control module is also used to receive external commands to output the corresponding pulse width modulation signal to the drive module, so that the drive module adjusts the drive pulse width of the drive power transistor to control the heating power change of the resonant heating module. Based on the change times of the first electrical signal flip signal and the second electrical signal flip signal detected by the control module, combined with the real-time detection results of the voltage detection module and the current detection module, a suitable range of heating power for the cookware is determined.

[0016] This application also provides an electromagnetic heating device. The electromagnetic heating device includes the electromagnetic heating control circuit described in the above embodiments.

[0017] Thus, the electromagnetic heating control circuit of this application detects the instantaneous current of the driving power transistor by setting an instantaneous current detection module. Based on the direction of the instantaneous current and whether the sampling voltage corresponding to the instantaneous current is greater than or equal to a preset voltage threshold, the control module outputs an electrical signal to the control module. The control module outputs a pulse width modulation signal to the driving module based on the electrical signal, so that the driving module adjusts the driving pulse width of the driving power transistor, thereby reducing the switching loss of the driving power transistor and improving the reliability of the driving power transistor.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0020] Figure 1 This is a schematic diagram of the electromagnetic heating control circuit according to certain embodiments of this application;

[0021] Figure 2 This is a schematic diagram showing the relationship between time and electrical signal in the electromagnetic heating control circuit of some embodiments of this application;

[0022] Figure 3 This is a schematic diagram showing the relationship between time and electrical signal in an electromagnetic heating control circuit according to certain embodiments of this application.

[0023] Main component reference numerals:

[0024] Electromagnetic heating control circuit 100;

[0025] Power supply module 10; rectifier and filter module 20, filter module 21, preliminary filter unit 22, rectifier unit 23; instantaneous current detection module 30, voltage acquisition unit 31, current direction determination unit 32, first comparator amplifier 321, current limit determination unit 33, second comparator amplifier 331; resonant heating module 40; drive power transistor 50; control module 60; drive module 70, voltage detection module 80, current detection module 90;

[0026] Sampling voltage V1; Reference voltage V 基 First electrical signal INT1, first flip signal INT11; second electrical signal INT2, second flip signal INT21; first capacitor C1; first resistor R1; first inductor L1; second capacitor C2; first voltage divider resistor R2; second voltage divider resistor R3; pull-up resistor R4; pull-up resistor R5; follower resistor R6. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0028] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance, or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly, referring to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or connections capable of communication; direct connections or indirect connections via an intermediate medium; and connections within two components or interactions between two components. Those skilled in the art can understand the specific meaning of these terms in this invention according to the specific circumstances.

[0030] The following disclosure provides many different embodiments or examples for implementing different structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0031] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0032] Please see Figure 1 This application discloses an electromagnetic heating control circuit 100. The electromagnetic heating control circuit 100 includes: a power supply module 10, a rectifier and filter module 20, an instantaneous current detection module 30, a resonant heating module 40, a drive power transistor 50, a control module 60, and a drive module 70.

[0033] Power module 10 is used to provide electrical energy. Power module 10 is used to supply AC power to rectifier and filter module 20.

[0034] The input terminal of the rectifier and filter module 20 is connected to the power supply module 10, and the first output terminal of the rectifier and filter module 20 is connected to the first input terminal of the control module 60.

[0035] The second output terminal of the rectifier and filter module 20 is connected to the first input terminal of the instantaneous current detection module 30. The rectifier and filter module 20 is used to filter and rectify the AC signal emitted by the power supply module 10 into a DC signal.

[0036] The second input terminal of the instantaneous current detection module 30 is connected to the first terminal of the resonant heating module 40. The output terminal of the instantaneous current detection module 30 is connected to the second input terminal of the control module 60. The emitter (E) of the drive power transistor 50 is connected to the second input terminal of the instantaneous current detection module 30. The instantaneous current detection module 30 is used to detect the instantaneous current when the drive power transistor 50 is conducting, and outputs an electrical signal based on the direction of the instantaneous current and whether the instantaneous current is greater than or equal to a preset voltage threshold. The preset voltage threshold is the maximum voltage limit corresponding to the maximum limit of the instantaneous current.

[0037] Understandably, since the emitter (E) of the driving power transistor 50 is connected to the second input terminal of the instantaneous current detection module 30, and the second input terminal of the instantaneous current detection module 30 is connected to the first terminal of the resonant heating module 40, the instantaneous current detection module 30 can receive both the current flowing from the driving power transistor 50 in the first direction A and the current flowing from the resonant heating module 40 in the second direction B at the instantaneous current detection module 30 when the driving power transistor 50 is turned on. Therefore, the instantaneous current detection module 30 can detect whether the instantaneous current flowing when the driving power transistor 50 is turned on is in the first direction A or the second direction B.

[0038] In addition, if the resonant voltage VC generated by the resonant heating module 40 cannot be reduced to 0V when the drive power transistor 50 is turned on, the drive power transistor 50 will not resonate to the zero-crossing point and will be turned on at a higher voltage, resulting in excessive instantaneous current and damage. Therefore, a preset voltage threshold that the maximum instantaneous current can reach can be set in the instantaneous current detection module 30, so as to determine whether the instantaneous current is greater than or equal to the preset voltage threshold, and then determine whether to output an electrical signal to the control module 60 to adjust the drive pulse width of the drive power transistor 50, so as to avoid serious damage to the drive power transistor 50, reduce the switching loss of the drive power transistor 50, and improve the reliability of the drive power transistor 50.

[0039] The resonant heating module 40 includes a resonant capacitor Cx and a coil inductance Lx. The resonant capacitor Cx and the coil inductance Lx can be connected in parallel or in series; this is not limited here. The resonant heating module 40 is used to heat cookware. The second terminal of the resonant heating module 40 is connected to the collector (C) of the driving power transistor 50. An external voltage detector can be connected to the circuit at the second terminal of the resonant capacitor C and the coil inductance L to detect the resonant voltage VC.

[0040] The output terminal of the control module 60 is connected to the input terminal of the drive module 70, and the gate (G) of the drive power transistor 50 is connected to the output terminal of the drive module 70. The control module 60 outputs a pulse width modulation (PWM) signal to the drive module 70 based on an electrical signal, so that the drive module 70 adjusts the drive pulse width of the drive power transistor 50. The PWM signal can be... Figure 2 or Figure 3 The pulse signal shown.

[0041] Thus, the electromagnetic heating control circuit 100 of this application detects the instantaneous current of the driving power transistor 50 by setting an instantaneous current detection module 30. Based on the direction of the instantaneous current and whether the sampling voltage corresponding to the instantaneous current is greater than or equal to a preset voltage threshold, the control module 60 outputs an electrical signal to the control module 60. The control module 60 outputs a pulse width modulation signal to the driving module 70 based on the electrical signal, so that the driving module 70 adjusts the driving pulse width of the driving power transistor 50, thereby reducing the switching loss of the driving power transistor 50 and improving the reliability of the driving power transistor 50.

[0042] Please see Figure 1 In some implementations, the instantaneous current detection module 30 includes a voltage acquisition unit 31, a current direction determination unit 32, and a current limit determination unit 33.

[0043] The first end of the voltage acquisition unit 31 is connected to the circuit between the rectifier filter module 20 and the resonant heating module 40. The voltage acquisition unit 31 is used to acquire the sampling voltage V1 at the moment when the drive power tube 50 is turned on in real time.

[0044] Understandably, the sampling voltage V1 at the instant the drive power transistor 50 is turned on is directly proportional to the instantaneous current at the instant the drive power transistor 50 is turned on. Therefore, the instantaneous current detection module 30 of this application can reflect the magnitude of the instantaneous current at the instant the drive power transistor 50 is turned on by obtaining the sampling voltage V1 at the instant the drive power transistor 50 is turned on.

[0045] The first terminal of the current direction determination unit 32 is connected to the second terminal of the voltage acquisition unit 31, the second terminal of the current direction determination unit 32 is grounded, and the third terminal of the current direction determination unit 32 is connected to the second input terminal of the control module 60. The current direction determination unit 32 is used to determine whether the sampled voltage V1 is greater than 0 to determine the direction of the instantaneous current, and outputs a first electrical signal INT1 to the control module 60. The first electrical signal INT1 can be a voltage or current signal with instantaneous current direction information.

[0046] At this time, when heating the pot with low power, the resonant voltage VC cannot be reduced to 0V. The driving power transistor 50 is turned on at a higher voltage. After the driving power transistor 50 is turned on, resonant oscillation will occur. The instantaneous current of the driving power transistor 50 flows from the emitter E of the driving power transistor 50 through the voltage acquisition unit 31 to the resonant heating module 40. That is, the direction of the instantaneous current is the first direction A. At this time, the sampling voltage V1 < 0V, so it can be determined that the direction of the instantaneous current of the driving power transistor 50 is the hard-on conduction mode.

[0047] When heating the cookware with high power, the resonant voltage VC drops below the reference voltage 0V, and the driving power transistor 50 turns on. At this time, the current first flows through the built-in diode of the driving power transistor 50. The current flows from the resonant heating module 40 through the voltage acquisition unit 31 to the emitter E of the driving power transistor 50. That is, the instantaneous current flows in the second direction B. The sampling voltage V1 is greater than 0. It can be determined that the instantaneous current of the driving power transistor 50 is in the freewheeling conduction mode.

[0048] The first terminal of the current limit determination unit 33 is connected to the second terminal of the voltage acquisition unit 31, and the second terminal of the current limit determination unit 33 is connected to the second input terminal of the control module 60. The current limit determination unit 33 is used to determine whether the sampled voltage V1 corresponding to the instantaneous current is greater than or equal to a preset voltage threshold. If the sampled voltage V1 is determined to be greater than or equal to the preset voltage threshold, a second electrical signal INT2 is output to the control module 60. The second electrical signal INT2 can be a voltage signal or a current signal.

[0049] The control module 60 is used to control the output pulse width modulation signal according to the first electrical signal INT1 and the second electrical signal INT2 to adjust the driving pulse width of the driving power transistor 50.

[0050] The preset voltage threshold corresponds to the maximum instantaneous current limit of the driving power transistor 50. When the sampled voltage V1 is greater than or equal to the preset voltage threshold, it indicates that the instantaneous current of the driving power transistor 50 is greater than or equal to the maximum current limit. Therefore, at this time, a second electrical signal can be output to the control module 60 to control the driving pulse width of the driving power transistor 50, so as to avoid the instantaneous current of the driving power transistor 50 being too large and severely damaged, thereby reducing the switching loss of the driving power transistor 50 and improving the reliability of the driving power transistor 50.

[0051] In detail, the current direction determination unit 32 of this application can determine the direction of the instantaneous current as the direction of the hard-open conduction mode based on the sampling voltage V1 being less than 0, and determine the direction of the instantaneous current as the direction of the freewheeling conduction mode based on the sampling voltage V1 being greater than 0.

[0052] That is, in the electromagnetic heating control circuit 100 of this application, the current direction determination unit 32 can determine the current conduction mode of the driving power transistor 50 according to the magnitude of the sampling voltage V1, so that the control module 60 can output different pulse width modulation signals according to different conduction modes to adjust the driving pulse width of the driving power transistor 50, so as to avoid the instantaneous current of the driving power transistor 50 being too large and severely damaged, thereby reducing the switching loss of the driving power transistor 50 and improving the reliability of the driving power transistor 50.

[0053] The above is a scheme for determining the magnitude of the instantaneous current of the drive power transistor 50 when the pot being heated by the resonant heating module 40 has not shifted. However, when the pot being heated by the resonant heating module 40 shifts, causing the instantaneous current of the drive power transistor 50 to be too large, the following determination scheme can be used to determine whether the instantaneous current of the drive power transistor 50 is too large, thereby adjusting the drive pulse width of the drive power transistor accordingly.

[0054] Specifically, please refer to Figure 1 In one embodiment, the control module 60 first receives a first flip signal INT11, where the first electrical signal INT1 output by the current direction determination unit 32 flips from a high level to a low level. Then, it receives a second flip signal INT21, where the second electrical signal INT2 output by the current limit determination unit 33 flips from a high level to a low level. The control module then outputs a first pulse width modulation signal to increase the driving pulse width of the driving power transistor 50 until no second flip signal INT21 is received within a preset time interval. The preset time interval can be, for example, 2 seconds, 2.5 seconds, 2.7 seconds, 3 seconds, 3.5 seconds, 4 seconds, 4.1 seconds, 4.5 seconds, 4.8 seconds, or 5 seconds, and is not limited here.

[0055] That is to say, such as Figure 2 As shown, during periods T1 and T2, when the pot being heated on the resonant heating module 40 shifts, causing the instantaneous current of the drive power transistor 50 to become too large, the control module 60 first receives the first switching signal INT11, which is the first electrical signal INT1 output by the current direction determination unit 32, which is the first switching signal INT11, which is the first switching signal INT21, which is the second switching signal INT2 output by the current limit determination unit 33, which is the second switching signal INT21 ...

[0056] At this point, it can be determined that the current driving power transistor 50 is in hard-on conduction mode. The instantaneous current of the driving power transistor 50 reaches or exceeds the limit. The output power of the current resonant heating module 40 is too low. Therefore, it is necessary to adjust the driving pulse width of the driving power transistor 50 to increase until the second electrical signal INT2 has no second flip signal INT21, indicating that the instantaneous current of the driving power transistor 50 will not be too large, thereby avoiding serious damage to the driving power transistor 50 due to excessive instantaneous current, thereby reducing the switching loss of the driving power transistor 50 and improving the reliability of the driving power transistor 50.

[0057] Please see Figure 1 In another embodiment, the control module 60 first receives a second flip signal INT21, which is a high-level to low-level transition signal from the second electrical signal INT2 output by the current limiting determination unit 33, and then receives a first flip signal INT11, which is a high-level to low-level transition signal from the first electrical signal INT1 output by the current direction determination unit 32. Then, it outputs a second pulse width modulation signal to reduce the driving pulse width of the driving power transistor 50 until no second flip signal INT21 is received within a preset time interval. The preset time interval can be, for example, 2 seconds, 2.3 seconds, 2.7 seconds, 3 seconds, 3.1 seconds, 4 seconds, 4.1 seconds, 4.4 seconds, 4.9 seconds, or 5 seconds, and is not limited here.

[0058] That is to say, such as Figure 3 As shown, during periods T3 and T4, when the pot being heated on the resonant heating module 40 shifts, causing the instantaneous current of the drive power transistor 50 to become too large, the control module 60 first receives the second flip signal INT21, which is the second electrical signal INT2 output by the current limiting determination unit 33, which flips from high level to low level, and then receives the first flip signal INT11, which is the first electrical signal INT1 output by the current direction determination unit 32, which flips from high level to low level.

[0059] At this point, it can be determined that the current driving power transistor 50 is in freewheeling conduction mode. The instantaneous current of the driving power transistor 50 reaches or exceeds the limit. The output power of the current resonant heating module 40 is too high. Therefore, it is necessary to adjust the driving pulse width of the driving power transistor 50 to reduce it until the second electrical signal INT2 has no second flip signal INT21, indicating that the instantaneous current of the driving power transistor 50 will not be too large, thereby avoiding serious damage to the driving power transistor 50 due to excessive instantaneous current, thereby reducing the switching loss of the driving power transistor 50 and improving the reliability of the driving power transistor 50.

[0060] Please see Figure 1 In some embodiments, the voltage acquisition unit 31 includes a first capacitor C1 and a first resistor R1, which are connected in series in the connection circuit between the rectifier filter module 20 and the resonant heating module 40.

[0061] In other words, the voltage acquisition unit 31 can acquire the sampling voltage corresponding to the instantaneous current when the driving power transistor 50 is turned on through the voltage division effect of the first capacitor C1 and the first resistor R1.

[0062] The current direction determination unit 32 also includes a first comparator amplifier 321. The first terminal of the first comparator amplifier 321 is connected between the first capacitor C1 and the first resistor R1, and the second terminal of the first comparator amplifier 321 is connected to the second input terminal of the control module 60. The third terminal of the first comparator amplifier 321 is grounded. The first comparator amplifier 321 is used to compare the sampled voltage V1 with the value of 0 to output a first electrical signal INT1.

[0063] In other words, the current direction determination unit 32 of this application can compare the magnitude of the sampling voltage V1 with that of 0 through the first comparator amplifier 321, thereby determining the current flow direction of the instantaneous current when the driving power transistor 50 is turned on, and then transmitting the determination result to the control module 60 in the form of the first electrical signal INT1.

[0064] The current limit determination unit 33 includes a second comparator amplifier 331. The first terminal of the second comparator amplifier 331 is connected to the connection circuit between the voltage acquisition unit 31 and the first comparator amplifier 321, and the second terminal of the second comparator amplifier 331 is connected to the second input terminal of the control module 60. The third terminal of the second comparator amplifier 331 is grounded. The second comparator 331 is used to compare the sampled voltage V1 with the value of a preset voltage threshold to output a second electrical signal INT2.

[0065] In other words, the current limit determination unit 33 of this application can compare the sampling voltage V1 with the preset voltage threshold value through the second comparator amplifier 322, thereby determining whether the instantaneous current when the drive power transistor 50 is turned on exceeds the current limit, and then transmit the determination result to the control module 60 in the form of the second electrical signal INT2.

[0066] For details, please refer to Figure 1 In some embodiments, the current limit determination unit 33 further includes a first voltage divider resistor R2 and a second voltage divider resistor R3 connected in parallel with the second comparator amplifier 331. The first voltage divider resistor R2 and the second voltage divider resistor R3 are used to provide a reference voltage V corresponding to a preset voltage threshold. 基 .

[0067] That is, the reference voltage V corresponding to the preset voltage threshold of this application 基 The current limit determination unit 33 can be provided by connecting the first voltage divider resistor R2 and the second voltage divider resistor R3 in parallel with the second comparator amplifier 331. The internal circuit structure of the current limit determination unit 33 is relatively simple.

[0068] In addition, such as Figure 1 As shown, the current direction determination unit 32 can also be connected to a pull-up resistor R4 at the signal output terminal, and the current limit determination unit 33 can also be connected to a pull-up resistor R5 at the signal output terminal. The function of the pull-up resistors R4 and R5 is to stabilize the potential of the output terminal.

[0069] The first comparator amplifier 321 and the second comparator amplifier 331 of this application are open-drain output circuit structures. Specifically, their working principle is to control the output pin level by controlling the conduction and cutoff of the MOSFET. When the MOSFET is on, the output pin is grounded; when the MOSFET is off, the output pin is connected to the external power supply through a pull-up resistor, forming a high-level output or a floating state.

[0070] The first voltage divider resistor R2 and the second voltage divider resistor R3 in the second comparator amplifier 331 divide the voltage to provide a reference voltage. Additionally, a follower resistor R6 can be connected. The second comparator amplifier 331 implements a circuit structure or function of following output through the follower resistor R6. The follower resistor R6 plays a key control and adjustment role, enabling the output signal to stably follow the changes in the input signal.

[0071] Please see Figure 1 In some embodiments, the rectifier-filter module 20 includes a filter module 21. The filter module 21 includes a first inductor L1 and a second capacitor C2, which together form an LC filter. The first capacitor C1 and the first resistor R1 are connected in series and then connected in parallel with the second capacitor C2, and the capacitance of the second capacitor C2 is greater than that of the first capacitor C1.

[0072] Understandably, the second capacitor C2 is a smoothing filter capacitor after the rectifier bridge. Its main function is to filter out the pulsating components in the rectified voltage, making the output voltage more stable. Therefore, the second capacitor C2 needs to have a large capacitance value to store enough charge to maintain the stability of the output voltage when the load changes.

[0073] The first capacitor C1 and the first resistor R1 are connected in series and then connected in parallel with the second capacitor C2. They form a voltage divider and filter branch that can provide a signal acquisition point H for acquiring the sampling voltage V1.

[0074] The first capacitor C1 is used to filter out high-frequency noise in the signal, making the acquired sampling voltage V1 signal more stable and reliable.

[0075] From a filtering perspective, the second capacitor C2, as the main filter capacitor, needs a sufficiently large capacitance to provide a stable output voltage. If the capacitance of the first capacitor C1 is too large, approaching or exceeding that of the second capacitor C2, then the first capacitor C1 will shun excessive current, affecting the filtering effect of the second capacitor C2 and leading to a decrease in output voltage stability. Furthermore, from a signal acquisition perspective, the capacitance of the first capacitor C1 should not be too large either. An excessively large capacitance will slow down the signal response, affecting the real-time performance and accuracy of current detection. Therefore, to ensure the filtering effect of the second capacitor C2 and the accuracy of signal acquisition, the capacitance of the second capacitor C2 is usually required to be greater than or equal to the capacitance of the first capacitor C1.

[0076] Furthermore, the electromagnetic heating control circuit of this application can also adjust the pulse width of the drive power transistor 50 to increase or decrease the power of the resonant heating module 40 in heating the pot when the resonant heating module 40 heats the pot with low or high power by the control module 60. Then, by detecting the flip signal of the first electrical signal INT1 and the flip signal of the second electrical signal INT2 of the first comparator amplifier 321 and the second comparator amplifier 331, the appropriate range of output power of the resonant heating module 40 when heating the pot with low or high power can be determined.

[0077] In other words, please refer to Figure 1 In some embodiments, the electromagnetic heating control circuit 100 further includes a voltage detection module 80 and a current detection module 90, both of which are connected to the control module 60. The other end of the voltage detection module 80 is connected to the power supply module 10. The other end of the current detection module 90 can be connected to the input circuit of the filter module 21.

[0078] The control module 60 is also used to receive external instructions to output corresponding pulse width modulation signals to the drive module 70, so that the drive module 70 adjusts the drive pulse width of the drive power tube 50 to control the change of the heating power of the resonant heating module. Based on the change time of the flip signal INT11 of the first electrical signal INT1 and the flip signal INT21 of the second electrical signal INT2 detected by the control module 60, and combined with the real-time detection results of the voltage detection module 80 and the current detection module 90, the appropriate range of the heating power of the cookware is determined.

[0079] Specifically, when the user sends an external command for the resonant heating module 40 to heat the cookware at a high starting power, the control module 60 can first adjust the driving pulse width of the driving power transistor 50 to increase, thereby controlling the heating power of the cookware to increase from the starting power to the maximum rated power value Pmax. Pmax can be, for example, 1.1 Pa, or other values, without limitation. During this process, when the control module 60 first detects the second electrical signal INT2 changing from high to low level (INT21), and then detects the first electrical signal INT1 changing from high to low level (INT11), it is determined that the driving power transistor 50 is in freewheeling conduction mode, and the freewheeling current of the driving power transistor 50 reaches or exceeds the current limit. Therefore, the control module 60 can adjust the driving pulse width of the driving power transistor 50 to decrease until the control module 60 does not detect the first electrical signal INT1 changing signal within a preset time period. Then, the control module 60 can detect and determine the power value at this time as P1 through the voltage detection module 80 and the current detection module 22 connected to the control module 60. Then, the driving pulse width of the driving power transistor 50 is further reduced until the power output of the cookware is K1P1, where 0.5≤K1≤1, thereby avoiding excessive freewheeling current of the driving power transistor 50. Therefore, when the cookware is heated at high power, in order to avoid the problem of excessive freewheeling current when the driving power transistor 50 is turned on and damaging the driving power transistor 50, the appropriate range of the heating power of the cookware is [K1P1, P1].

[0080] When the user sends an external command for the resonant heating module 40 to heat the cookware with a low starting power, the control module 60 can first adjust the driving pulse width of the drive power transistor 50 to increase, thereby controlling the heating power of the cookware to increase from the starting power. During this process, when the control module 60 first detects the first electrical signal INT1 changing from high to low (INT11), and then detects the second electrical signal INT2 changing from high to low (INT21), and subsequently no longer detects the second electrical signal INT2's switching signal INT21, the control module 60 can determine the current power value as P2 through the voltage detection module 80 and current detection module 22 connected to the control module 60. The driving pulse width of the drive power transistor 50 is then increased until the cookware's heating power output reaches the rated heating power, for example, K2P2, where 1≤K2≤2. Therefore, when the cookware is heated with low power, to avoid the drive power transistor 50 from hard-starting, the appropriate range for the cookware's heating power is [P2, K2P2].

[0081] like Figure 1As shown, the rectifier-filter module 20 may further include a preliminary filter unit 22 and a rectifier unit 23. The preliminary filter unit 22 is used to perform preliminary filtering on the AC signal output by the power supply module 10. The rectifier module 23 is used to rectify the AC signal after preliminary filtering and convert it into a DC signal. The control module 60 also includes a power supply module' that provides power to the control module 60.

[0082] This application also provides an electromagnetic heating device. The electromagnetic heating device includes the electromagnetic heating control circuit 100 described in the above embodiments. The electromagnetic heating device can be an induction cooker or an induction furnace, and is not limited thereto.

[0083] Thus, the electromagnetic heating control circuit 100 in the electromagnetic heating device of this application detects the instantaneous current of the driving power transistor 50 by setting an instantaneous current detection module 30. Based on the direction of the instantaneous current and whether the sampling voltage corresponding to the instantaneous current is greater than or equal to a preset voltage threshold, the control module 60 outputs an electrical signal to the control module 60. The control module 60 outputs a pulse width modulation signal to the driving module 70 based on the electrical signal, so that the driving module 70 adjusts the driving pulse width of the driving power transistor 50, thereby reducing the switching loss of the driving power transistor 50 and improving the reliability of the driving power transistor 50.

[0084] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. An electromagnetic heating control circuit, characterized in that, The electromagnetic heating control circuit includes: a power supply module, a rectifier and filter module, a transient current detection module, a resonant heating module, a drive power transistor, a control module, and a drive module. The input terminal of the rectifier and filter module is connected to the power supply module; the first output terminal of the rectifier and filter module is connected to the first input terminal of the control module; the second output terminal of the rectifier and filter module is connected to the first input terminal of the transient current detection module; the second input terminal of the transient current detection module is connected to the first terminal of the resonant heating module, which includes a resonant capacitor and a coil inductor, and is used to heat a cookware; the second terminal of the resonant heating module is connected to the collector of the drive power transistor; the emitter of the drive power transistor is connected to the second input terminal of the transient current detection module; the output terminal of the control module is connected to the input terminal of the drive module; the gate of the drive power transistor is connected to the output terminal of the drive module; and the output terminal of the transient current detection module is connected to the second input terminal of the control module. The power module is used to provide electrical energy; The rectifier and filter module is used to filter and rectify the AC signal emitted by the power supply module into a DC signal; The instantaneous current detection module is used to detect the instantaneous current when the drive power transistor is turned on, and outputs an electrical signal based on the direction of the instantaneous current and whether the instantaneous current is greater than or equal to a preset voltage threshold. The control module is used to output a pulse width modulation signal to the drive module according to the electrical signal, so that the drive module adjusts the drive pulse width of the drive power transistor.

2. The electromagnetic heating control circuit according to claim 1, characterized in that, The instantaneous current detection module includes a voltage acquisition unit, a current direction determination unit, and a current limit determination unit; The first end of the voltage acquisition unit is connected to the circuit between the rectifier filter module and the resonant heating module. The voltage acquisition unit is used to acquire the sampling voltage at the moment when the drive power tube is turned on in real time. The first terminal of the current direction determination unit is connected to the second terminal of the voltage acquisition unit, the second terminal of the current direction determination unit is grounded, and the third terminal of the current direction determination unit is connected to the second input terminal of the control module; the current direction determination unit is used to determine whether the sampled voltage is greater than 0 to determine the direction of the instantaneous current, and outputs a first electrical signal to the control module; The first end of the current limit determination unit is connected to the second end of the voltage acquisition unit, and the second end of the current limit determination unit is connected to the second input end of the control module. The current limit determination unit is used to determine whether the sampled voltage corresponding to the instantaneous current is greater than or equal to the preset voltage threshold. If the sampled voltage is determined to be greater than or equal to the preset voltage threshold, a second electrical signal is output to the control module. The control module is used to control the output pulse width modulation signal according to the first electrical signal and the second electrical signal, so as to adjust the driving pulse width of the driving power transistor.

3. The electromagnetic heating control circuit according to claim 2, characterized in that, The current direction determination unit is used to determine whether the direction of the instantaneous current is the direction of the hard-on conduction mode based on the sampling voltage being less than 0, and to determine whether the direction of the instantaneous current is the direction of the freewheeling conduction mode based on the sampling voltage being greater than 0.

4. The electromagnetic heating control circuit according to claim 2, characterized in that, The control module first receives a first flip signal from the current direction determination unit, in which the first electrical signal flips from a high level to a low level. Then it receives a second flip signal from the current limit determination unit, in which the second electrical signal flips from a high level to a low level. The control module then outputs a first pulse width modulation signal to increase the driving pulse width of the driving power transistor until no second flip signal is received within a preset time interval.

5. The electromagnetic heating control circuit according to claim 2, characterized in that, The control module first receives a second flip signal from the current limiting determination unit, in which the second electrical signal flips from a high level to a low level. Then, it receives a first flip signal from the current direction determination unit, in which the first electrical signal flips from a high level to a low level. The control module then outputs a second pulse width modulation signal to reduce the driving pulse width of the driving power transistor until no second flip signal is received within a preset time interval.

6. The electromagnetic heating control circuit according to claim 2, characterized in that, The voltage acquisition unit includes a first capacitor and a first resistor, which are connected in series in the connection circuit between the rectifier filter module and the resonant heating module.

7. The electromagnetic heating control circuit according to claim 6, characterized in that, The current direction determination unit further includes a first comparator amplifier. The first terminal of the first comparator amplifier is connected between the first capacitor and the first resistor, and the second terminal of the first comparator amplifier is connected to the second input terminal of the control module. The third terminal of the first comparator amplifier is grounded. The first comparator amplifier is used to compare the value of the sampled voltage with 0 to output the first electrical signal. The current limit determination unit includes a second comparator amplifier. The first terminal of the second comparator amplifier is connected to the connection circuit between the voltage acquisition unit and the first comparator amplifier. The second terminal of the second comparator amplifier is connected to the second input terminal of the control module. The third terminal of the second comparator amplifier is grounded. The second comparator is used to compare the sampled voltage with the preset voltage threshold value to output the second electrical signal.

8. The electromagnetic heating control circuit according to claim 7, characterized in that, The current limit determination unit further includes a first voltage divider resistor and a second voltage divider resistor connected in parallel with the second comparator amplifier. The first voltage divider resistor and the second voltage divider resistor are used to provide a reference voltage for a preset voltage threshold.

9. The electromagnetic heating control circuit according to claim 7, characterized in that, The electromagnetic heating control circuit further includes a voltage detection module, and the rectifier and filter module further includes a current detection module. Both the voltage detection module and the current detection module are connected to the control module. The control module is also used to receive external instructions to output the corresponding pulse width modulation signal to the drive module, so that the drive module adjusts the drive pulse width of the drive power tube to control the heating power change of the resonant heating module. Based on the change time of the first electrical signal flip signal and the second electrical signal flip signal detected by the control module, combined with the real-time detection results of the voltage detection module and the current detection module, the appropriate range of the heating power of the cookware is determined.

10. An electromagnetic heating device, characterized in that, The electromagnetic heating device includes the electromagnetic heating control circuit according to any one of claims 1 to 9.

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