TECHNICAL FIELD

The invention relates to a power and control circuit for an induction hob operated with both half-bridge series resonance and single-switch partial resonance.

BACKGROUND OF THE ART

The induction hobs operate by means of a coil that creates a magnetic field. Induction-heated hobs are widely utilized in both industrial and household kitchens. These hobs have glass or glass ceramic surfaces. In induction heated hobs, the ignition system is activated by a control panel. The control panel is to be in the form of a touchpad or a button. Induction hob models, produced in various sizes and dimensions, are produced in single or different numbers of cooking zones. In these hobs, only a pot, pan or a container with a magnetic charge is heated. Since induction-heated hobs directly heat the bottom of the pan, the possibility of an accident is also minimized. Thus, heating efficiency can be achieved safely.

Induction hobs are third-generation kitchen cooking systems. The heating feature of these hobs works fast. This is because a magnetic charge, which is heated by being placed on the hob, turns into a heat source, not the hob itself. In this way, the possibility of burning the hands of the hob itself is eliminated. Induction hotplates and hotplates, which are not placed on a magnetic load suitable for heating, hardly get hot. This, for example, minimizes the possibility of the food being cooked in a pot getting burned. In some models of induction hobs, power induction and electromagnetism provide heat generation where it is needed. In other words, the heat is created instantly at the base of a load with a heated magnetic feature, and when the heating is turned off, the heat transferred from the hob is lost instantly.

The working system of induction hobs is based on Faraday's Law. Induction current is a varying electric current. Eddy currents are formed by the effect of a magnetic field on ferromagnetic alloys. The magnetic field itself is generated from an electrical source. These hobs have a fast-working system. Induction heating systems have a power and control circuit. The power and control circuit consists of a switched-mode inverter or inverters that provide the heating. An inverter circuit is completed by the application of a magnetic charge on the hob. The main components of classical induction heating systems are the rectifier and the resonant inverter. Today, resonant inverters are available in different resonant inverter topologies depending on the balance between cost and performance. Commonly used resonant inverter topologies are half-bridge series resonant inverter topologies and partial resonance inverter topologies.

WO2014167814 discloses an induction cooker in which it is detected whether there is an object on the hob before induction heating and if the object is removed before heating, it is determined that the object is not on the hob. This induction heater includes a plurality of heating coils, a plurality of inverters, a plurality of switching circuits, an instruction means, a sensor assembly, and a pan detection means. In the present invention, the number of inverters is less than the number of heating coils to provide a high-frequency current to the heating coils. Additionally, it aims to reduce the cost of an induction heater with a large number of heating coils while ensuring safety.

BRIEF DESCRIPTION OF THE INVENTION

The object of the invention is to provide a power and control circuit for an induction heated cooker that can provide multiple magnetic heating in both half-bridge series resonance and single-switch partial resonance operation to meet the low-cost product expectation in induction heated hobs.

In order to achieve the aforementioned objectives, the invention comprises a power and control circuit for an induction hob comprising a control circuit adapted to control a magnetic heating mode corresponding to the heating signal from a user interface via a microcontroller and to detect a heated load via the microcontroller; a power circuit connected to the control circuit so as to provide heating in the magnetic heating mode corresponding to the incoming heating signal and at least one switched-mode inverter converts the voltage applied from an AC or a DC power source to a high-frequency current on a circuit path; an upper switch assembly including at least one semiconductor switch connected on the power circuit; a subswitch assembly including at least one semiconductor switch connected on the power circuit; a heater assembly with at least one coil connected to the circuit path where the upper switch group and the lower switch group are connected to each other and a resistor as the equivalent of the load disposed on the coil; a resonance capacitor connected via the circuit path to each heater assembly; at least one partial resonance switch assembly connected via circuit path between the resonance capacitor and the heater assembly characterized in that the power circuit is a half-bridge the inverter in which the series resonance switched magnetic heating mode is configured to be enabled with the upper switch assembly or the lower switch assembly; inverter in which a single-switched portion of the power circuit operates in resonant magnetic heating mode is configured to be activated with a sub-switch assembly or a partial resonance switch assembly. Thus, an induction hob with multiple magnetic heating that can operate with both half-bridge series resonance and single-switch partial resonance is provided.

In a preferred embodiment of the invention, each semiconductor switch in the partial resonance switch group in the power circuit in which the single-switch partial resonance magnetic heating is activated is configured to operate as a semiconductor switch or to operate as a controlled diode. Thus, a semiconductor switch is provided to operate in two different tasks under different alternans of the AC power supply.

In a preferred embodiment of the invention, each coil of the heater assembly in the power circuit where the half-bridge series resonance switched magnetic heating is activated is configured to operate at the same frequency. Thus, in the half-bridge series resonant operating mode of the inverter in the power circuit, a configuration is obtained that ensures that each load heated by multiple coils operates at the same frequency value of each coil.

In a preferred embodiment of the invention, each partial resonance switch group in the operatively adjusted power circuit connected to the DC power source is configured to be located on the downstream of the heater assembly. Thus, a selective design characteristic of the power circuit operating under DC mains voltage is provided.

In a preferred embodiment of the invention, each partial resonance switch assembly in the operatively tuned power circuit connected to the AC power supply is configured to be upstream of the heater assembly. Thus, a selective design characteristic of the power circuit operating under AC mains voltage is provided.

A preferred embodiment of the invention comprises the operably configured power circuit connected to the AC power supply is connected to each semiconductor switch and comprises at least one free pass diode and at least one capacitor connected in parallel resonance. Thus, the power circuit is configured to operate efficiently under AC mains voltage.

In a preferred embodiment of the invention, each heater assembly coil is configured to operate without being connected to each other. Thus, the induction heated hob is configured to provide independent heating in accordance with the incoming heating signal. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is the illustration of the AC power supply connected circuit diagram for the power and control circuit for an induction hob according to the subject matter.

Figure 2 is the illustration of the DC power supply connected circuit diagram for the power and control circuit for an induction hob.

Figure 3 is the illustration of the circuit diagram of the power and control circuit for an induction hob of the invention in half-bridge series resonance switched mode with an AC power supply connected.

Figure 4 is the illustration of the circuit diagram in half-bridge series resonance switched mode with a DC power supply connected to the power and control circuit for an induction hob

Figure 5 is the illustration of a single-switch partial resonance operating circuit diagram with an AC power supply connected to the power and control circuit for an induction hob.

Figure 6 is the illustration of a single-switch partial resonance operative circuit diagram with a DC power supply connected to the power and control circuit for an induction hob.

DETAILED DESCRIPTION OF THE INVENTION

In this detailed explanation, the invention is explained without any limitation and only with reference to examples to better explain the subject matter.

Figure 1 shows the general AC power supply connected circuit diagram of the power and control circuit for an induction hob of the invention. In Figure 2, a general diagram of the DC power supply connected circuit diagram of the power and control circuit for an induction heating cooker of the invention is shown. Figure 3 shows the circuit diagram of the halfbridge series resonance switched operating mode with the AC power supply connected to the power and control circuit for an induction hob. Figure 4 shows the circuit diagram of a half-bridge series resonance switched circuit with a DC power supply connected to the power and control circuit for an induction hob according to the subject matter invention. Figure 5 shows a single-switch partial resonance operating circuit diagram with an AC power supply connected to the power and control circuit for an induction hob. Figure 6 shows a singleswitch partial resonance operating circuit diagram with a DC power supply connected to the power and control circuit for an induction-heated cooker, which is the subject of the invention. In a power and control circuit (10), the heating mode is set to operate from a user interface (12) and the heating signal comes to a control circuit (14). In the control circuit (14), there is a microcontroller (16) which is set to activate the predetermined algorithms. The microcontroller (16) is configured to control a magnetic heating mode with the corresponding predetermined algorithms stored in its memory. In addition, the microcontroller (16) is adjusted in such a way that it detects a heated load (41 ) with the appropriate algorithms predetermined in its memory. Thus, the operating control circuit (14) is provided with both heating mode control and a load detection. The control circuit is then connected to a power circuit. The power circuit (18) is arranged to initiate a magnetic heating mode. Thus, it is configured to conduct the heating. At least one inverter (44) (46) (48) (50) (52) (54) (60) (62) (66) is provided on the power circuit (18) configured to convert voltage applied from a DC power source (24) or an AC power source (22) to high-frequency current on a circuit path (26). Each inverter here is a semiconductor switch (44) (46) (50) (52) (60) (62) and a set of switches (48) (54) (66). In the power circuit (18) set to operate at a DC mains voltage (24), there is a semiconductor switch (44) (46) (50) (52) (60) (62) connected on the circuit paths. A regulated power circuit (18) to operate at an AC mains voltage (22) comprises at least one free pass diode (32) with resonance connection in parallel to the semiconductor switch (44) (46) (50) (52) (60) (62) and at least one capacitor (28). In addition, in the power circuit (18), a switch group (48) (54) (66) is obtained such that at least two switches (44) (46) (50) (52) (60) (62) are connected. In the power circuit (18) according to the subject of the invention, there are also at least two switch groups (48) (54) (66) connected. There is at least one heater assembly (40) connected to each switch assembly (48) (54) (66). A resistor (36) and a coil (38) are connected to the resistor on each heater assembly. In addition, a resonance capacitor (42) is connected to each heater assembly (40) via the circuit path (26). The power circuit (18) includes a first switch (44) of the n-channel type connected to the AC power supply (22) via the circuit path (26) and connected such at the free pass diode (32) is reverse biased. The power circuit (18) includes a first switch (44) of the n-channel type connected via circuit path (26) to the DC power supply (24). The power circuit (18) connected to the AC power source (22) is having a second switch (46) of p-channel type connected to the output of the first switch (44) via the circuit path (26) and connected such that the free pass diode (32) is forward biased. The power circuit (18) connected to the DC power source (22) includes a second switch (46) of the p-channel type connected via the circuit path (26) to the output of the first switch (44). By connecting the first switch (44) and the second switch (46) to each other via the circuit path (26), an upper switch group (48) configured to provide a half-bridging is obtained. There is a third n-channel type switch (50) connected to the output of the second switch (46) of the upper switch group (48) via the circuit path and connected under the AC mains voltage (22) such that the free pass diode (32) is in the reverse polarity direction. There is a third switch (50) of n-channel type connected to the output of the second switch (46) of the upper switch group (48) via the circuit path and under the DC mains voltage (24). In the power circuit (18) with AC mains voltage (22) connected, there is a fourth switch (52) of the p-channel type connected via the circuit path (26) to the output of the third switch (50) and connected such that the free pass diode (32) is forward biased. In the power circuit (18) with the DC mains voltage (22) connected, there is a fourth switch (52) of the p-channel type connected via the circuit path (26) to the output of the third switch (50). By connecting the third switch (50) and the fourth switch (52) to each other via the circuit path (26), a sub-switch group (54) configured to provide a resonance line is obtained. In a half-bridge series-resonant operating mode of the power circuit (18), the upper switch assembly (48) or lower switch assembly (54) is connected to the appropriate switch assembly (48) from an intermediate node (56), enabling an appropriate heating mode connected heater assembly (40) and the resonance capacitor (42) are adjusted to operate. In a single-switch partial resonance operating mode of the power circuit (18), the sub-switch assembly is set to operate in partial resonance. There is a heater assembly (40) connected between the output of the upper switch group (48) and the input of the lower switch group (54) and connected in a way that provides separate circuit lines. In the power circuit (18) coupled to the AC power supply (22) or the DC power supply (24), there is at least one partial resonance switch assembly (66) connected to a partial resonance node (64). Each partial resonance switch group (66) consists of an n-channel type partial resonance upper switch (60) and a p-channel type partial resonance lower switch (62) coupled to a partial resonance upper switch (60). Each partial resonance upper switch (60) and each partial resonance lower switch (62) in the power circuit (18) operating under AC mains voltage (22) has a parallel resonance connected free pass diode (32) and capacitor (28). Each semiconductor switch (50) (52) (60) (62) in the partial resonance switch group (66) in the power circuit (18) in which the single-switch partial resonance magnetic heating is activated, with connection to the AC mains voltage (22) (24) operates in the form of a semiconductor switch and a regulated or controlled diode. By activating the upper switch group (48) to which the first and second switches (44) are connected, providing partial resonance switching in the power circuit (18) in which single-switch partial resonance magnetic heating is activated, with DC mains voltage connection, the upper switch group (48) is activated, from the top of the circuit to the bottom of the heater assembly. It is arranged to work together with the partial resonance switch groups (66) to which the partial resonance switches (60) (62) disposed on its lower side are connected. Each heater assembly coil (38) in the power circuit (18) in which half-bridged series resonance switched magnetic heating is activated includes its configuration to operate at the same frequency value. Each partial resonance switch assembly (66) in the operatively tuned power circuit (18) connected to the DC power supply (24) includes its configuration to be downstream of the heater assembly (40). Each partial resonance switch assembly (66) in the operatively tuned power circuit (18) connected to the AC power source (22) includes its configuration to be upstream of the heater assembly (40). In addition, each heater assembly coil (38) in the power circuit (18) operating under AC or DC voltage (22) (24) operates independently of each other and is configured to be controllable. In this way, different power levels can be applied to each coil (38) in the circuit (18), and while operating a coil, other coils cannot be operated. Here, independent operation of any coil is not possible in general topologies. Therefore, the total amount of coil (38) to be used in the circuit (18) should be determined at the beginning of the design. In the power and control circuit (10), the converter is designed to operate in both halfbridge series resonance and single-switch partial resonance. A single heated load (41) of the resonant circuit (48) (54) (66), the resistor (36) and coil (38) located in the heater assembly (40) are modeled. Here, the amount of load (41) desired to be heated can be increased. However, the increase in the load amount (41 ) is limited by the current capacity of the semiconductors of the first switch, second switch, third switch and fourth switch (44) (46) (50) (52) carrying the main current of the entire circuit. In the circuit (18), no drive signals are applied to the semiconductors of the first switch (44) and the second switch (46) during the single-switch partial resonance operation period. These semiconductor switches (44)(46) are held in cutoff. Each partial resonance upper switch and each partial resonance lower switch semiconductors (60) (62) are used as switches or controlled diodes for single-switch partial resonance operation, depending on the alternance of the AC (22) grid. The total coil (38) current passing through the circuit flows over the third switch and fourth switch semiconductors (50) (52), which are used as the control diode operable. During the operation of the circuit (18), depending on whether the load (41 ) to be heated is single or multi-coil (38), the respective partial resonance working switch groups (54) (66) of each coil (38) are activated. For example, in order to energize the load (41) from the single heater assembly (40) activated in the single coil (38) state, the third and fourth switch semiconductors (50) (52) in the block in the sub-switch group are at the positive and negative alternans of the AC input voltage (22) respectively. In addition, each semiconductor switch (44) (46) (50) (52) (60) (62) in the circuit is a bipolar transistor with an isolated gate.

REFERENCE NUMBERS

10 Power and control circuit

12 User interface 14 Control interface

16 Microcontroller

18 Power circuit

22 AC power supply

24 DC power supply

26 Circuit path

28 Capacitors

32 Free pass diode

36 Resistor

38 Coil

40 Heater assembly

41 Load

42 Resonant capacitors

44 First key

46 Second key

48 Upper key group

50 Third key

52 Fourth key

54 Subkey group

56 Intermediate nodes

60 Partial resonance top switch

62 Partial resonance subkey

64 Partial resonance nodes

66 Partial resonance switch group