ES2606687T3 - Induction heating cooking plate - Google Patents

Abstract

An induction heating cooking plate (1) comprising a rectifier bridge (2) that converts alternating current into direct current, a filter circuit (3) arranged at the output of the rectifier bridge (2), one or more of an induction coil (4) through which the coil current (IL) passes during heating of the container (K) located on the upper plate (P) of the induction heating plate (1) with the In order to be within the zone (B) of efficient heating, a resonant circuit (6) having a resonant capacitor (5) connected in parallel to the induction coil (4), a power switch (7) that drives the resonant circuit (6), a collector node (8) in which the resonant voltage (Vce) is generated during non-conduction times of the power switch (7), a drive circuit (9) that provides the switch (7) power be powered, an interface (10) user, a control unit (11) that regulates the operation of the power switch (7) by means of the drive circuit (9) in accordance with the heating setting selected through the interface (10) of user, and - a voltage control circuit (12) connected to the collector node (8) and provide control of the resonant voltage (Vce), in which the control unit (11) maintains the resonant voltage (Vce) monitored by means of the circuit (12) for controlling the voltage and energy transferred to the constant vessel (K); the induction heating plate being characterized in that - a current control circuit (13) is connected in series with the induction coil (4), providing the monitoring of the coil current (IL), and - the unit ( 11) Control decides that the container (K) is within the zone (B) of efficient heating if the changes (ΔIL) of the coil current monitored by means of the current control circuit (13) are greater than changes (ΔIL - lim) of the bobbin limit current pre-recorded in its memory for different power scales selected through the user interface (10).

Description

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

DESCRIPTION

Induction heating plate

The present invention relates to an induction heating cooking plate in which it is detected whether or not the container placed on it is in the appropriate position.

The induction heating hob works according to the principle of heating a cast iron or ferromagnetic steel cookware, for example, a pot, with the effect of the magnetic field generated by the induction coil. In the state of the art, quasi-resonant single switch circuits (SSQR) formed by a power switch and a resonance capacitor are used to drive an individual induction coil. Quasi-resonant single switch circuits (SSQR) are preferred due to cost advantage; however, they operate in a narrower range of energy frequencies and can supply energy to cookware only within a certain range of voltage and energy. In induction heating plates in which the quasi-resonant single switch circuits (SSQR) are used, problems are found in the detection of different types of cookware and changes in the position of the cookware in the hob burner. In addition, difficulties arise in detecting the position of kitchen utensils in voltage fluctuations of the electricity grid and in different temperature conditions. In some induction heating hobs, a multi-zone structure - multiple coils is used, the heating can be maintained over the entire surface of the hob and flexibility is provided to the user. In this type of induction heating cooking plates, induction coils of various shapes and sizes are located on the surface of the cooking plate. Under the tension of the variable electric network, the input voltage depending on the energy setting and under variable temperature conditions, the detection of the position of kitchen utensils and, in addition, the characteristic features such as the diameter, the type and The ferromagnetic properties during transmittance of energy to the kitchen utensil is quite critical for products in which multiple coils are used and also the quasi-resonant single switch circuits (SSQR). In induction heating cooking plates, the position of the container located on the induction coil is generally defined by the circular edge lines drawn on the surface of the cooking plate. If it is aligned with the induction coil in accordance with the predetermined edge lines, the container can be heated efficiently. The user is allowed to slide the container slightly out of said edge lines and the container can be heated in the desired power setting, provided it is in the efficient heating zone. With the condition of being in the efficient heating zone, the container must be heated according to the power setting selected by the user and without being affected by the conditions of the variable electrical network and temperature and if the container slides Outside the efficient heating zone, this situation will be detected and the power transmitted to the vessel must be interrupted. If it is not detected that the container slides out of the efficient heating zone, the container cannot be heated according to the selected power setting and the circuit board can be damaged.

European patent application EP2282606 refers to an induction device control procedure. The presence or absence of the container in the induction coil, the resistivity and its dimensions are detected by comparing the resonance voltage with a predetermined fixed reference voltage in the control unit.

European patent EP1629698 explains an induction cooking system comprising a power inverter, a microprocessor, a protection circuit and a pot detection circuit.

In Japanese patent application JP4371108, an induction heating cooking device comprising a kitchen utensil detection circuit is explained.

In Japanese patent application JP2011023163, a rice cooker is explained in which the existence or non-existence of a pan on the induction heater or if the pan is in a designated position is detected under conditions of power supply voltage unstable

In Japanese patent application JP2007066837, a rice cooker is explained in which the presence of kitchen utensils such as the spoon, a knife on the induction heater is detected under fluctuating energy source voltage conditions.

US patent application 2010/006563 A1 describes an induction heating cooktop comprising a bridge rectifier that converts alternating current into direct current, a filter circuit arranged at the output of the bridge rectifier, an induction coil through which the coil current passes during the heating of the vessel placed on the upper plate of the induction heating hob in order to be within the efficient heating zone, a resonant circuit having a condenser resonant connected in parallel to the induction coil, a power switch that drives the resonant circuit, a collector node on which the resonance voltage is generated during the moments of non-conduction of the power switch, a control circuit that provides the power switch to be operated, a control unit that regulates the operation of the switch supply via the drive circuit according to the heating setting selected through the

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

user interface, and a voltage control circuit connected to the collector node and providing control of the resonance voltage, in which the control unit maintains the resonant voltage monitored by means of the voltage control circuit and the power transferred to the constant vessel.

The objective of the present invention is the realization of an induction heating cooking plate in which the position of the container located on the induction coil is detected by virtue of the input voltage of the electrical network and variable temperature conditions.

The induction heating hob made in order to achieve the objective of the present invention, explained in the first claim and the respective claims thereof, comprises a rectifying bridge that converts the current of the alternating electrical network into direct current, a resonant circuit having an induction coil and a resonant capacitor, a power switch, for example an IGBT, that drives the resonant circuit, a collecting node on which the resonance voltage is generated, a current control circuit, connected in series with the induction coil, which provides the current of the coil, which passes through the induction coil, to be controlled by its conversion into voltage data, and a voltage control circuit that provides control of the resonance voltage (ignition switch voltage) generated in the collecting node.

In one embodiment of the present invention, the current control circuit comprises a current detection resistor connected in series with the induction coil, and in another embodiment of the present invention comprises a current transformer connected in series with the coil of induction and a current detection resistor connected in parallel to the secondary side of the current transformer.

In one embodiment of the present invention, the voltage control circuit comprises a voltage divider that decreases the resonance voltage, which allows for easy measurement thereof.

The control unit decides that the vessel is within the efficient heating zone on the top plate of the iron, where the vessel is allowed to slide slightly outside the induction coil level, if the current changes of the coil monitored by means of the current monitoring circuit are greater than the current changes of the limit coil pre-recorded in its memory for different power scales selected through the user interface.

By detecting that the vessel is within the efficient heating zone, the control unit maintains the resonance voltage, controlled by means of the voltage monitoring circuit, by increasing the resonance voltage if it is low or the decrease if it is high, so that the energy transferred to the container is enabled to be kept constant while the container is within the efficient heating zone, even if it slipped slightly outside the induction coil level.

By detecting that the vessel slides out of the efficient heating zone, the control unit stops the operation of the induction heating hob.

In the induction heating hob of the present invention, the control unit keeps the energy transferred to the vessel constant under conditions of variable mains voltage and temperature in accordance with the heating settings selected through the interface of Username. By accurately detecting the alignment of the container in the induction coil, the power switch that drives the induction coil, and other electronic components, is prevented from being damaged.

The induction heating hob made in order to achieve the objective of the present invention is illustrated in the attached figures, where:

Figure 1 is a schematic view from above of an induction heating hob.

Figure 2 is a schematic view of the control circuit of an induction heating hob.

Fig. 3 is the schematic view of the control circuit of an induction heating hob in an embodiment of the present invention.

The elements illustrated in the figures are numbered as follows:

1. Induction heating cooktop

2. Bridge rectifier

3. Filtering circuit

4. Induction coil

5. Resonant condenser

6. Resonant circuit

7. Power switch

8. Collector Node

9. Drive circuit

10. User Interface

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

11. Control unit

12. Voltage monitoring circuit

13. Current monitoring circuit

14. Current detection resistance

15. Current transformer

16. Tension Divider

The induction heating cooking plate (1) comprises a rectifier bridge (2) that converts the alternating current received from the electrical network into direct current, a high frequency filtering circuit (3) at the output of the bridge (2) rectifier and one or more of an induction coil (4) through which the current (Il) of the coil passes during heating of the container (K) located on the upper plate (P) of the plate (1) of induction heating cooking in order to be within the efficient heating zone (B).

On the upper plate (P) of the induction heating plate (1), the container (K) or other ferromagnetic cooking vessels are placed so that they are within an efficient heating zone (B) that allows them go a little beyond the limit line (S) that defines their position, at the level (4) of the induction coil and that provides efficient heating of them (figure 1).

The induction heating cooking plate (1) comprises a resonant circuit (6) having a resonant capacitor (5) connected in parallel to the induction coil (4), a power switch (7), for example an IGBT (bipolar insulated gate transistor), which has a collector, an emitter and a freewheel diode, which drives the resonant circuit (6), which is in a driving state in the turned-off position, provided that the resonant capacitor (5) to be charged during the conduction time, which interrupts the conduction in the converted position, providing the resonant capacitor (5) that is discharged during the non-conduction time, and which provides the energy to be released from the coil ( 4) induction in the container (K), a collector node (8) in which the resonance voltage (Vce) or in other words the voltage of the collector-emitter of the power switch (7) is generated during the moments of no driving (off) of the inte power switch (7), a drive circuit (9) that provides the power switch (7) to be driven with the drive voltage (Vge) at the required level, a user interface (10) that provides heating of the container (K) at the desired power level and at which the user adjusts the heating setting, and a control unit (11), for example a microcontroller, which regulates the operation of the power switch (7) by means of of the drive circuit (9) in accordance with the heating setting selected through the user interface (10) (figure 2, figure 3).

While the container (K) located on the upper plate (P) of the induction heating plate (1) is within the efficient heating zone (B) having a diameter larger than the limit line (S) marked on the upper plate (P), the container (K) is heated by receiving constant power in accordance with the heating setting (power scale) selected through the user interface (10). The user is allowed to slide the container (K) slightly out of the level of the induction coil (4). If the vessel (K) slides out of the efficient heating zone (B), the power that is transferred from the induction coil (4) to the vessel (K) is interrupted.

On the induction heating plate (1), the conduction times in which the power switch (7) is in the off position are determined by the heating configuration selected through the user interface (10) . The non-conduction times in which the power switch (7) is in the on position are determined by the control unit (11) based on the characteristic features of the container (K) located in the induction coil (4) , the alignment of the container (K) in the induction coil (4), the conditions of the mains voltage and the temperature of the container (K). During the non-conduction times of the power switch (7), resonance voltage (Vce) is generated in the collector node (8), the current (Il) of the coil passes through the induction coil (4) and The energy is transferred to the container (K).

The induction heating plate (1) of the present invention comprises,

- a voltage monitoring circuit (12) connected to the collector node (8) and providing control of the resonant voltage (Vce) during the transmission of energy to the container (K), and

- a current control circuit (13) connected in series with the induction coil (4) and providing control of the current (Il) of the coil by converting it into voltage data during the transmission of energy to the container (K ),

- the control unit (11) that decides that the container (K) is within the efficient heating zone (B) if the coil current changes (AIl) monitored by means of the control circuit (13) of the current are greater than the changes (AIl - lim) of the coil current limit pre-recorded in its memory for different power scales selected through the user interface (10) and that keeps the resonant voltage (Vce) constant through intervention in the resonant voltage (Vce) monitored by means of the voltage monitoring circuit (12), therefore it allows the energy transferred to the container (K) to remain constant.

If the coil current changes (AIl) monitored by the current control circuit (13) are

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

smaller than the changes (AIl - lim) of the coil current Ifmite pre-recorded in its memory for different power scales, the control unit (11) decides that the container (K) slides out of the zone (B) of Efficient heating, interrupts the current (Il) of the coil and stops the operation of the induction heating plate (1).

On the induction heating plate (1), when the container (K) slides a little outside on the induction coil (4), whether or not the container (K) is within the zone (B ) Efficient heating is determined by means of the current control circuit (13). If the vessel (K) is within the efficient heating zone (B), the control unit (11) maintains the resonant voltage (Vce) and therefore the energy transferred to the vessel (K) constant under varying voltage conditions of the electrical network and temperature by means of the voltage monitoring circuit (12) and the drive circuit (9). Even if the level of the induction coil (4) slipped slightly, the vessel (K) is enabled to be heated within the efficient heating zone (B) according to the heating establishment selected through the user interface (10).

In one embodiment of the present invention, the control unit (11) compares the constant resonance voltage values (Vce-sb) previously registered in its memory and corresponding to the heating configuration selected through the interface (10) with the real resonance voltage (Vce) values monitored through the voltage monitoring circuit (12), intervenes in the power switch (7) by means of the actuating circuit (9) and allows the voltage ( Vce) real resonant is matched with the constant resonance voltage (Vce-sb), thus allowing the energy transferred from the induction coil (4) in the container (K) to remain constant.

In one embodiment of the present invention, the current control circuit (13) comprises a current detection resistor (14) that is connected in series with the induction coil (4) and converts the current (Il) of the coil in tension data (figure 3). The control unit (11) receives the voltage data related to the coil current (Il) of the resistance detection terminals (14).

In another embodiment of the present invention, the current control circuit (13) comprises a current transformer (15) connected in series with the induction coil (4) and the decrease in the current (Il) of the coil a a level that can be detected by the control unit (11) and the current detection resistor (14) connected in parallel with the secondary side of the current transformer (15) (figure 2).

In another embodiment of the present invention, the voltage control circuit (12) comprises a voltage divider (16) having resistors (R1, R2) connected in series with the collector node (8) and a voltage is applied (Vce) easy to measure, with a low level of resonance to the control unit (11) by dividing the resonant voltage (Vce) (figure 2, figure 3).

In the induction heating plate (1) of the present invention, the constant energy is transferred to the container (K) in the zone (B) of efficient heating in which the container (K) is allowed to slide a just outside the level of the induction coil (4) and that the container (K) slips causes changes in the coil current (Il). In order to detect the position of the container (K) placed on the upper plate (P), the resonant voltage (Vce) is kept constant and the current (AIl) of the coil that changes as the container (K) is monitored ) slides out through the induction coil (4). In order to keep the energy transferred to the vessel (K) constant in the selected heating configuration through the user interface (10), the control unit (11) keeps the resonant voltage (Vce) constant and detects if the container (K) is present or not or if the alignment of the container (K) in the induction coil (4) is appropriate by controlling the changes in current (AI) of the coil caused by the container (K) being slipped . It prevents the power switch (7) and the other components of the electronic circuit from being damaged. In different heating settings, the position of the container (K) located in the induction coil (4) is detected precisely under conditions of varying mains voltage and temperature, and the container (K) is provided to be heated With a constant energy.

It is to be understood that the present invention is not limited by the embodiments described above and a person skilled in the art can easily introduce different embodiments. These should be considered within the scope of the protection postulated by the claims of the present invention.

Claims (6)

5 10 fifteen twenty 25 30 35 40 Four. Five 1. An induction heating cooking plate (1) comprising a rectifier bridge (2) that converts alternating current into direct current, a filter circuit (3) arranged at the output of the rectifier bridge (2), one or more than one induction coil (4) through which the coil current (Il) passes during the heating of the container (K) located on the upper plate (P) of the induction heating plate (1) in order to be within the zone (B) of efficient heating, a resonant circuit (6) having a resonant capacitor (5) connected in parallel to the induction coil (4), a power switch (7) that it drives the resonant circuit (6), a collector node (8) in which the resonance voltage (Vce) is generated during the non-conduction times of the power switch (7), a drive circuit (9) that provides that the power switch (7) is activated, an interface (10) of us uary, a control unit (11) that regulates the operation of the power switch (7) by means of the drive circuit (9) in accordance with the heating setting selected through the user interface (10), and - a voltage control circuit (12) connected to the collector node (8) and provide control of the resonant voltage (Vce), in which the control unit (11) keeps the resonant voltage (Vce) monitored by means of the voltage control circuit (12) and the energy transferred to the constant vessel (K); the induction heating plate being characterized because - a current control circuit (13) is connected in series with the induction coil (4), providing the monitoring of the coil current (Il), and - the control unit (11) decides that the container (K) is within the efficient heating zone (B) if the coil current changes (AIl) monitored by means of the current control circuit (13) they are greater than the changes (AIl) of the coil current limit pre-recorded in its memory for different power scales selected through the user interface (10). 2. An induction heating cooking plate (1) according to claim 1, characterized in that the control unit (11) that decides that the container (K) slides out of the efficient heating zone (B) and stops the operation of the induction heating cooking plate (1) if the changes (AIl) of the coil current monitored by means of the current control circuit (13) are smaller than the current changes (AIl-lim) of the limit coil. 3. An induction heating cooking plate (1) according to claim 1 or 2, characterized in that the control unit (11) comparing the constant resonance voltage (Vce-sb) pre-recorded in its memory and corresponding to the heating configuration selected through the user interface (10) with the real resonance voltage (Vce), which intervenes in the power switch (7) by means of the drive circuit (9) and which allows the voltage ( Vce) of real resonance is matched with the constant resonance voltage (Vce-sb). 4. An induction heating cooking plate (1) according to any one of the preceding claims, characterized in that the current control circuit (13) comprises a current detection resistor (14) which is connected in series with the coil (4) induction and converting the current (Il) of the coil into voltage data. 5. An induction heating cooking plate (1) according to any one of claims 1 to 3, characterized in that the current control circuit (13) comprises a current transformer (15) connected in series with the coil ( 4) induction and reduction of the current (Il) of the coil, and the resistance (14) of current detection connected in parallel with the current transformer (15). 6. An induction heating cooking plate (1) according to any one of the preceding claims, characterized in that the voltage control circuit (12) comprises a voltage divider (16) having resistors (R1, R2) connected in series with the collector node (8) and that a resonant voltage (Vce) easy to measure, of low level is applied to the control unit (11) by dividing the resonant voltage (Vce).