Continuous low-power control device of induction cooker

Abstract

The utility model discloses a continuous low-power control device of an induction cooker, and relates to the technical field of induction cookers. The EMC circuit is respectively connected with the rectification filter circuit and the zero-crossing and voltage detection circuit, the rectification filter circuit is respectively connected with the resonance circuit and the IGBT driving circuit, and the IGBT driving circuit and the zero-crossing and voltage detection circuit are both connected with the control and signal acquisition circuit; according to the utility model, low-power continuous heating is realized by adopting a wave loss form and combining with a special IGBT driving waveform, so that the heat loss of the IGBT is effectively reduced, and the service life is prolonged; in order to realize a continuous low-power heating function, a certain number of IGBTs are turned on and a certain number of IGBTs are turned off by taking a certain number of commercial power periods as a total period in a wave loss mode; the IGBT is driven by a special driving waveform in different stages, so that low-power continuous heating of the induction cooker can be realized, the impact of a hard switching effect on the IGBT is reduced, and the heat loss is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of induction cookers, and particularly relates to a continuous low-power control device for an induction cooker. Background Art

[0002] Induction cookers are common cooking appliances in households at present, which can provide precise temperature and firepower control, save energy effectively, and have the advantages of cooking without an open flame, etc. For the common single-tube induction cookers on the market, the lowest continuous power output is generally between 50% and 100% of the maximum power, about 1000W. Obviously, it cannot achieve the effect requirements of slow simmering or keeping warm like traditional stoves, which poses new requirements for single-tube induction cookers, that is, lower continuous low-power heating.

[0003] In order to achieve a lower power output in the prior art, the conduction time of the IGBT is usually reduced, and an intermittent heating working mode is adopted. For example, it works for 2 seconds and stops for 8 seconds, with a second-level interval period, and the low-power heating is achieved by taking the average.

[0004] The prior art uses an intermittent heating method to achieve this lower power output. Although the average power output can reach the predetermined low-power purpose, this method has a slow switching of the heating cycle of the induction cooker (second level), and the firepower suddenly turns on and off, resulting in uneven heating. This discontinuous heating method cannot truly achieve a low-power working state, and it takes longer and consumes more power to cook food than the continuous boiling state.

[0005] The induction cooker in the prior art cannot truly achieve continuous low-power heating mainly because the magnitude of the heating power is directly proportional to the conduction time of the IGBT. The longer the conduction time, the greater the reverse voltage generated after LC resonance, and the greater the heating power. When the induction cooker needs to output low power, the conduction time of the IGBT will be reduced, and the pulse width of the drive signal will be shortened. However, when the pulse width is reduced to a certain extent (that is, when the power is reduced to about 1000W), the reverse voltage generated by LC resonance will have a small oscillation amplitude of the resonance voltage due to the small energy provided, so that the voltage cannot drop to zero potential when swinging downward, resulting in the next IGBT being turned on before the collector-emitter voltage (VCE) drops to zero voltage, forming a so-called "hard switching" state, which will cause greater loss and higher temperature rise of the IGBT and shorten the service life of the IGBT. Summary of the Utility Model

[0006] To solve the problems mentioned in the above background art, the purpose of the utility model is to provide a continuous low-power control device for an induction cooker.

[0007] A continuous low-power control device for an induction cooker of the present utility model includes an EMC circuit, a rectifier filter circuit, a resonant circuit, an IGBT drive circuit, a zero-crossing and voltage detection circuit, and a control and signal acquisition circuit; the EMC circuit is respectively connected to the rectifier filter circuit and the zero-crossing and voltage detection circuit, the rectifier filter circuit is respectively connected to the resonant circuit and the IGBT drive circuit, and the IGBT drive circuit and the zero-crossing and voltage detection circuit are both connected to the control and signal acquisition circuit.

[0008] Preferably, the EMC circuit includes a varistor and a line filter capacitor; one end of the live wire of the mains is connected to one end of the fuse, and the other end of the fuse and the neutral wire of the mains are respectively connected to both ends of the varistor and the line filter capacitor.

[0009] Preferably, the rectifier filter circuit includes a rectifier bridge, an inductor, a smoothing filter capacitor, and a detection resistor; pin 1 of the rectifier bridge is connected to one end of the inductor, the other end of the inductor is connected to one end of the smoothing filter capacitor, the other end of the smoothing filter capacitor is connected to one end of the detection resistor, and the other end of the detection resistor is connected to pin 3 of the rectifier bridge and grounded.

[0010] Preferably, the resonant circuit includes a resonant capacitor and a coil disc; both ends of the resonant capacitor are respectively connected to both ends of the coil disc.

[0011] Preferably, the zero-crossing and voltage detection circuit includes a first diode, a second diode, a second resistor, and a third resistor; the cathodes of the first diode and the second diode are connected together and connected to one end of the second resistor, the other end of the second resistor is connected to one end of the third resistor, and the other end of the third resistor is grounded.

[0012] Preferably, the IGBT drive circuit includes an IGBT module and a first resistor; the G pole of the IGBT module is connected to one end of the first resistor.

[0013] Preferably, the control and signal acquisition circuit is a main control chip, the model of the main control chip is HT45F0036, and pin 2 of the main control chip is grounded.

[0014] Compared with the prior art, the beneficial effects of the present utility model are as follows: low-power continuous heating is achieved through the mutual cooperation of the EMC circuit, the rectifier filter circuit, the resonant circuit, the IGBT drive circuit, the zero-crossing and voltage detection circuit, and the control and signal acquisition circuit. It is achieved in the form of wave loss and in combination with a special IGBT drive waveform, effectively reducing the thermal loss of the IGBT and extending its service life. The specific advantages are:

[0015] I. To achieve the continuous low-power heating function, the wave-loss method is adopted, with a certain number of mains power cycles as the total cycle. A certain number of IGBTs are turned on and a certain number of IGBTs are turned off. At the same time, to reduce the thermal loss and impact of the IGBTs, different types of drive signals are used to drive the IGBTs in a time-division and segmented manner.

[0016] II. By adopting the wave-loss method and driving the IGBTs with special drive waveforms in a time-division and staged manner, not only can the low-power continuous heating of the induction cooker be achieved, but also the impact of the hard-switching effect on the IGBTs can be reduced, and the thermal loss of the IGBT switches can be lowered. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For ease of explanation, the present utility model will be described in detail by the following specific embodiments and accompanying drawings.

[0018] Figure 1 is a schematic structural diagram of the present utility model;

[0019] Figure 2 is a flowchart of the mains power zero-crossing interruption in the present utility model;

[0020] Figure 3 is a flowchart of the timing interruption in the present utility model.

[0021] In the figure: FU1 - fuse; RT1 - varistor; C1 - line filter capacitor; DB1 - rectifier bridge; L1 - inductor; C2 - smoothing filter capacitor; R3 - detection resistor; C3 - resonant capacitor; COIL1 - coil; D1 - diode one; D2 - diode two; R905 - resistor one; R906 - resistor two; R907 - resistor three; IGBT1 - IGBT module; U1 - main control chip. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To make the objectives, technical solutions, and advantages of the present utility model clearer and more understandable, the present utility model will be described below through specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present utility model. The structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not intended to limit the limiting conditions under which the present utility model can be implemented. Therefore, they do not have any technical substance. Any modification of the structure, change in the ratio relationship, or adjustment of the size, without affecting the effects that the present utility model can produce and the objectives that can be achieved, should still fall within the scope covered by the technical content disclosed in the present utility model. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present utility model.

[0023] Here, it should also be noted that in order to avoid obscuring the present utility model due to unnecessary details, only the structures and / or processing steps closely related to the solution according to the present utility model are shown in the drawings, while other details less relevant to the present utility model are omitted.

[0024] As Figure 1 shown, the following technical solutions are adopted in this specific embodiment: It includes an EMC circuit, a rectifier filter circuit, a resonant circuit, an IGBT drive circuit, a zero-crossing and voltage detection circuit, and a control and signal acquisition circuit; the EMC circuit is respectively connected to the rectifier filter circuit and the zero-crossing and voltage detection circuit, the rectifier filter circuit is respectively connected to the resonant circuit and the IGBT drive circuit, and the IGBT drive circuit and the zero-crossing and voltage detection circuit are both connected to the control and signal acquisition circuit; the EMC circuit includes a varistor RT1 and a line filter capacitor C1; the rectifier filter circuit includes a rectifier bridge DB1, an inductor L1, a smoothing filter capacitor C2, and a detection resistor R3; the resonant circuit includes a resonant capacitor C3 and a line coil COIL1; the zero-crossing and voltage detection circuit includes a diode D1, a diode D2, a resistor R906, and a resistor R907; the IGBT drive circuit includes an IGBT module IGBT1 and a resistor R905; the control and signal acquisition circuit is a main control chip U1, the model of the main control chip U1 is HT45F0036, one end of the live wire of the mains electricity is connected to one end of the fuse FU1, and the other end of the fuse FU1 and the neutral wire of the mains electricity are respectively connected to both ends of the varistor RT1, the positive pole of the diode D1, the positive pole of the diode D2, both ends of the line filter capacitor C1, and the 2nd and 4th pins of the rectifier bridge DB1. The negative poles of the diode D1 and the diode D2 are connected to each other and connected to one end of the resistor R906. The other end of the resistor R906 is respectively connected to one end of the resistor R907 and the 3rd pin of the main control chip U1. The other end of the resistor R907 is grounded. The 1st pin of the rectifier bridge DB1 is connected to one end of the inductor L1. The other end of the inductor L1 is connected to one end of the smoothing filter capacitor C2, one end of the resonant capacitor C3, and one end of the line coil COIL1. The other end of the smoothing filter capacitor C2 is respectively connected to one end of the detection resistor R3 and the E pole of the IGBT module IGBT1. The other end of the detection resistor R3 is connected to the 3rd pin of the rectifier bridge DB1 and grounded. The other end of the resonant capacitor C3 and the other end of the line coil COIL1 are both connected to the C pole of the IGBT module IGBT1. The G pole of the IGBT module IGBT1 is connected to one end of the resistor R905. The other end of the resistor R905 is connected to the 4th pin of the main control chip U1. The 2nd pin of the main control chip U1 is grounded.

[0025] As Figure 2 、 Figure 3As shown, in this specific embodiment, the wave loss realizes a continuous low-power mode: by controlling the number of wave losses in different fixed AC cycle stages, different powers are output. For example, taking 5 AC Cycles as a low-power continuous heating cycle, within this cycle, the IGBT is turned on for a certain period of time. When the rated power output is reached, the IGBT is turned off, as shown in the flowchart of the mains zero-crossing interruption.

[0026] In this specific embodiment, the wave loss realizes a continuous low-power mode. In essence, it is also a kind of intermittent heating mode, but the intermittent cycle is changed from the previous second-level intermittent cycle to the mains cycle (millisecond level). Without special treatment, compared with the intermittent heating mode of the prior art, the number of hard switches of the IGBT will be more frequent and the heating will be more serious. Therefore, as shown in the flowchart of the timing interruption, special treatment is carried out on the IGBT drive waveform in stages by time: when the zero-crossing interruption occurs, within the zero-crossing interruption subroutine, the parameters related to the low-power output are initialized and the timing count is cleared. After that, within the timing interruption subroutine, the control program outputs different types of IGBT drive waveforms in stages according to the timing count value.

[0027] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

[0028] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A continuous low-power control device for an induction cooker, characterized in that: It includes an EMC circuit, a rectifier and filter circuit, a resonant circuit, an IGBT drive circuit, a zero-crossing and voltage detection circuit, and a control and signal acquisition circuit; the EMC circuit is respectively connected to the rectifier and filter circuit and the zero-crossing and voltage detection circuit, the rectifier and filter circuit is respectively connected to the resonant circuit and the IGBT drive circuit, and the IGBT drive circuit and the zero-crossing and voltage detection circuit are all connected to the control and signal acquisition circuit.

2. The continuous low power control device for an induction cooker according to claim 1, characterized in that: The EMC circuit comprises a varistor (RT1) and a cross-line filter capacitor (C1); the live wire of the mains is connected to one end of the fuse (FU1), and the other end of the fuse (FU1) and the neutral wire of the mains are respectively connected to the varistor (RT1) and the two ends of the cross-line filter capacitor (C1).

3. The continuous low power control device for an induction cooker according to claim 1, characterized in that: The rectifier and filter circuit comprises a rectifier bridge (DB1), an inductor (L1), a smoothing filter capacitor (C2), and a detection resistor (R3); pin 1 of the rectifier bridge (DB1) is connected to one end of the inductor (L1), the other end of the inductor (L1) is connected to one end of the smoothing filter capacitor (C2), the other end of the smoothing filter capacitor (C2) is connected to one end of the detection resistor (R3), and the other end of the detection resistor (R3) is connected to pin 3 of the rectifier bridge (DB1) and is grounded.

4. The continuous low power control device for an induction cooker according to claim 1, characterized in that: The resonant circuit comprises a resonant capacitor (C3) and a wire coil (COIL1); two ends of the resonant capacitor (C3) are respectively connected to two ends of the wire coil (COIL1).

5. The continuous low power control device for an induction cooker according to claim 1, characterized in that: The zero-crossing and voltage detection circuit comprises a diode 1 (D1), a diode 2 (D2), a resistor 2 (R906), and a resistor 3 (R907); the cathodes of the diode 1 (D1) and the diode 2 (D2) are connected to one end of the resistor 2 (R906), the other end of the resistor 2 (R906) is connected to one end of the resistor 3 (R907), and the other end of the resistor 3 (R907) is grounded.

6. The continuous low power control device for an induction cooker according to claim 1, characterized in that: The IGBT driving circuit comprises an IGBT module (IGBT1) and a resistor one (R905); a G pole of the IGBT module (IGBT1) is connected to one end of the resistor one (R905).

7. The continuous low power control device for an induction cooker according to claim 1, characterized in that: The control and signal acquisition circuit is a main control chip (U1), the model of the main control chip (U1) is HT45F0036; pin 2 of the main control chip (U1) is grounded.

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