WO2023043385A2

WO2023043385A2 - A power and control circuit control method for an induction hob

Info

Publication number: WO2023043385A2
Application number: PCT/TR2021/050943
Authority: WO
Inventors: Metin OZTURK; Fatih ZUNGOR; Burhaneddin EMRE; Sema ISIK CALISKAN
Original assignee: Mamur Teknoloji Sistemleri San. A.S.
Priority date: 2021-09-15
Filing date: 2021-09-15
Publication date: 2023-03-23
Also published as: WO2023043385A3

Abstract

A power and control circuit control method for an induction hob comprising the steps of enabling a single-switch partial resonance heating mode (102) operating in the audible frequency range of the power circuit (18) from the control circuit (14) and the corresponding inverter (50) (52) (54) (60) (62) (66) on the power circuit (18) in case of a control circuit (14) detects at least two loads (41) on the hob; activating the related inverter (50) (52) (54) (60) (62) line in the power circuit by activating the single-switch partial resonance heating mode (102) operating in the audible frequency range of the power circuit (18) from the control circuit (14) if it is determined by the control circuit (14) that the output power in the power circuit (18) is greater than a predetermined power value for a situation where the control circuit (14) detects a single load on the hob; enable the corresponding inverter (44) (46) (48) (50) (52) (54) line in the power circuit to be operational by activating a half-bridge series resonance switched heating mode (112) operating at a value below the audible frequency of the power circuit (18) from the control circuit (14) if it is determined by the control circuit that the output power in the power circuit (14) is less than a predetermined power value for a situation where the control circuit (14) detects a single load on the hob.

Description

A POWER AND CONTROL CIRCUIT CONTROL METHOD FOR AN INDUCTION HOB

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 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 hob that can provide multiple magnetic heating in both half-bridge series resonance and single-switch partial resonance operation to satisfy the low-cost product expectation in induction hobs.

In order to achieve the above objective, the invention relates to a control method of the control and power circuit for an induction hob comprising the steps of control of a magnetic heating mode in accordance with the heating signal coming from a user interface in an induction heating hob via a microcontroller having a preloaded algorithm contained in a control circuit and detecting of at least one heated load via the microcontroller; performing the heating operation in accordance with the magnetic heating mode with a power circuit in the hob where the magnetic heating mode is controlled by the control circuit and the load is detected; converting the voltage applied from a DC or AC power source to high frequency current by means of at least one switched inverter provided on the power circuit where the heating is performed; performing the conversion with at least one partial resonance switch assembly and a switch assembly having at least one semiconductor switch on the power circuit; performing the heating process with a coil connected in a way that conducts the electric current, and at least one heater group having a resistor corresponding to the load disposed on the coil in the equivalent circuit. The method further comprising the steps of in case of the control circuit detects at least two loads on the hob initiating a single-switch partial resonance heating mode operating in the audible frequency range of the power circuit from the control circuit activating the corresponding inverter line in the power circuit; in a case where the control circuit detects a single load on the hob and if the control circuit detects that the output power in the power circuit is greater than a predetermined power value, the control circuit will utilize the control circuit in the audible frequency range of the power circuit operationally by activating the corresponding inverter line in the power circuit by activating the operating single-switch partial resonance heating mode; in case of the control circuit detects a single load on the hob where the control circuit detects that the output power in the power circuit is less than a predetermined power value, the control circuit initiate the control circuit at a value below the audible frequency value of the power circuit by activating the relevant inverter line in the power circuit by activating a working half-bridge series resonance switched heating mode. Thus, an induction hob with multiple magnetic heating that can operate with both half-bridge series resonance and single-switch partial resonance is provided.

A preferred embodiment of the invention operates without interconnection of the coils in the power circuit where single-switch partial resonance heating is activated. Thus, the induction hob is configured to provide independent heating in accordance with the incoming heating signal.

In a preferred embodiment of the invention, each semiconductor switch in the partial resonance switch group in the power circuit where single-switch partial resonance magnetic heating is activated operates as a semiconductor switch or 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 group in the power circuit where the half-bridge series resonance switched magnetic heating is activated operates at the same frequency value. Thus, in the half-bridge series resonant operation mode of the inverter in the power circuit, a configuration is obtained that ensures that each heated load operates at the same frequency value of each coil.

In a preferred embodiment of the invention, each partial resonance switch group in the operatively tuned power circuit connected to the DC power supply is on the downstream of the heater group. 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 disposed on the 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 is that the operably configured power circuit coupled to the AC power supply comprises at least one free pass diode and at least one capacitor, resonantly coupled in parallel to each semiconductor switch. Thus, the power circuit is configured to operate efficiently under AC mains voltage.

BRIEF DESCRIPTION OF THE FIGURES

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

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

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

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

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

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

Figure 7 is a flowchart illustration of the control method for the power and control circuit of 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 illustrates the AC power supply connected circuit diagram for the power and control circuit of an induction hob. Figure 2 illustrates the DC power supply connected circuit diagram for the power and control circuit of an induction hob. Figure 3 shows the circuit diagram in half-bridge series resonance switched operating form with an AC power supply connected for the power and control circuit of an induction hob. Figure 4 shows the circuit diagram in half-bridge series resonance switched mode with a DC power supply connected to the power and control circuit of an induction hob. Figure 5 shows the circuit diagram for the power and control circuit of an induction hob in single-switch partial resonance operating mode with an AC power supply connected. Figure 6 shows a single-switch partial resonance operating circuit diagram with a DC power supply connected to the power and control circuit of an induction hob, 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 inbound heating signal transmitted 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 adjusted to control a magnetic heating mode (68) with the appropriate predetermined algorithms 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, an operating control circuit (14) is provided, both by controlling the heating mode and detecting a load. The control circuit is then connected to a power circuit. The power circuit (18) is arranged to engage a magnetic heating mode (68). At least one inverter (44) (46) (48) on the power circuit (18) configured to convert the voltage applied from a DC power source (24) or an AC power source (22) on a circuit path (26) to high frequency current (50) (52) (54) (60) (62) (66). 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. At least one free pass diode (32) with resonant connections in parallel to the semiconductor switch (44) (46) (50) (52) (60) (62) in a regulated power circuit (18) to operate at an AC mains voltage (22) 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), which is the subject of the invention, there are at least two switch groups (48) (54) (66) connected. There is at least one heater group (40) connected to each switch assembly (48) (54) (66). There is a resistor (36) and a coil (38) connected to the resistor on each heater group. In addition, there is a resonance capacitor (42) connected to each heater group (40) via the circuit path (26). The power circuit (18) includes a first switch (44) of the n-channel type connected to the AC (22) power supply via the circuit path (26) and connected such that the free pass diode (32) is reverse polarized. The power circuit (18) comprises a first switch (44) of the n-channel type connected via the circuit path (26) to the DC (24) power supply The power circuit (18) connected to the AC power source (22) includes a second n-channel type switch (46) 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 polarized. The power circuit (18) connected to the DC power source (22) includes a second switch (46) of the n-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 halfbridging 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 n-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 n- channel type, connected via the circuit path (26) to the output of the third switch (50). A subswitch group (54) configured to provide a resonance line is obtained by connecting the third switch (50) and the fourth switch (52) to each other via the circuit path (26). 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 group (40) and the resonance capacitor (42). 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 group (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 assembly (66) consists of an n-channel type partial resonance upper switch (60) and an n-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) operates as a semiconductor switch or as a controlled diode. Each semiconductor switch (50) (52) (60) (62) in the partial resonance switch group (66) in the power circuit (18) in which single-switch partial resonance magnetic heating is activated, with connection to AC mains voltage (22) (24) each semiconductor switch (50) (52) (60) (62) is operable as a semiconductor switch or as a controlled diode. By activating the upper switch group (48) with DC mains voltage connection 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, from the upper side of the circuit to the lower side of the heater group 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 group coil (38) in the power circuit (18) in which half-bridged series resonance switched magnetic heating is activated configured 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) configured 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 supply (22) includes its configuration to be upstream of the heater assembly (40). In addition, each heater group 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 group (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 grid (22). 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 switch groups (54) (66) of each coil (38) are activated. For example, in order to energize the load (41) from the single heater group (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.

Figure 7 shows the flowchart of the control method for the power and control circuit of an induction hob. In the control method, the magnetic heating mode (68) suitable for the heating signal inbound to the control circuit (14) is activated. With the preloaded algorithms, the initial settings (70) suitable for the magnetic heating mode (68) are provided in the control circuit (14). First of all, a load control (72) is performed so that magnetic heating (68) is provided. Thus, the control (72) is made whether there is a load on the induction hob. In the load control (72), a load query (74) is made regarding whether the heating operation has the determined load or loads. If no load can be detected as a result of the load query (74), or if the presence of the load condition is not detected, a no-load detection (76) is made and the load query process (74) is returned. If any load is detected as a result of the load query (74), a load is detected (78), and the control (80) (86) (104) steps are made on the coil or coils. First, the load on the hob is controlled (80) on three coils. In this process step, if no-load is determined on three coils, no load (84) is defined and proceeded to two coils control. If it is determined that the load is on three coils, a load number control (90) process is initiated by determining the result of detection (82) on a load three coils. In load control over two coils (86), when it is determined that the load is on two coils, a load number control (90) process step is initiated by determining the result of detection (88) of a load on two coils. If the load is not on two coils, a no-load detection (87) is made and proceeded to a load one coil control step (104). If more than one load is detected in the load number control (90) operation step, a multi-load detection (92) is obtained, and an independent heating control inquiry (96) operation step is initiated. If single load is detected in the process step of the load number control (90), a single load detection result (94) is obtained, and the heating process is provided as a half-bridge series resonant operation (112) of the power and control circuit (10). If individually heated loads (41) are detected on the coils (38), an independent heating detection (98) is obtained, providing the heating operation as a single-switched partial resonance operation (102) of the power and control circuit (10). If, in an independent heating control query (96), a condition of the loads (41) on the coils (38) providing dependent heating is detected, no independent heating detection (100) is made, and the heating operation is performed (112) with a half-bridge series resonant resonance circuit of the power and control circuit (10). In the step of controlling the load on the one coil, it is determined that the presence of the load (41) is in place and the output power control of the heating (106) is performed. In the output power control (106) process step, if the output power is less than 1000-Watt (108), the heating process is provided as a half-bridge series resonant operation (112) of the power and control circuit (10). If the output power is greater than 1000-Watt (110) in the output power control (106) process step, the heating operation is provided as a singleswitch partial resonance operation (102) of the power and control circuit (10).

REFERENCE NUMBERS

10 Power and control circuit

12 User interface

14 Control circuit

16 Microcontrollers

18 Power circuit

22 AC power supply

24 DC power supply

26 Circuit path

28 Capacitors

32 Free pass diodes

36 Resistor

38 Coils

40 Heater group

41 Load

42 Resonant capacitor

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

68 Magnetic heating mode

70 Initial settings

72 Load control 74 Load control query

76 No load detection

78 Load detection

80 Load control on three coils

82 Detection of load on three coils

84 Detection of no load on three coils

86 Load control on two coils

87 No load detection on two coils

88 Detection of load on two coils

90 Load count control

92 Single multiple load detection

94 Load detection

96 Independent heating control

98 Independent heating detection

100 No independent heating detection

102 One-switch partial resonance operation

104 Load control on single coil

106 Output power control

108 Output power less than 1000-W

110 Output power greater than 1000-W

112 Half bridge series resonant operation

Claims

CLAIMS - A control and power circuit control method for an induction hob comprising the steps of control (96) of a magnetic heating mode (68) in accordance with the heating signal coming from a user interface (12) in an induction heating hob via a microcontroller (16) having a preloaded algorithm (70) contained in a control circuit (14) and detecting (72) of at least one heated load (41 ) via the microcontroller (16); performing the heating operation in accordance with the magnetic heating mode (68) with a power circuit (18) in the hob where the magnetic heating mode (68) is controlled by the control circuit (14) and the load is detected (74); converting the voltage applied from a DC (24) or AC (22) power source to high frequency current by means of at least one switched inverter (44) (46) (48) (50) (52) (54) (60) (62) (66) provided on the power circuit (18) where the heating is performed; performing the conversion with at least one partial resonance switch assembly (66) and a switch assembly (48) (54) having at least one semiconductor switch (44) (46) on the power circuit; performing the heating process with a coil (38) connected in a way that conducts the electric current, and at least one heater group (40) having a resistor (36) corresponding to the load (41) disposed on the coil (14) in the equivalent circuit (14) comprising the steps of in case of the control circuit (14) detects at least two loads (41 ) on the hob initiating a single-switch partial resonance heating mode (102) operating in the audible frequency range of the power circuit (18) from the control circuit (14) activating the corresponding inverter (50) (52) (54) (60) (62) (66) line in the power circuit (18); in a case where the control circuit (14) detects a single load on the hob and if the control circuit (14) detects that the output power in the power circuit (18) is greater than a predetermined power value, the control circuit (14) will utilize the control circuit (14) in the audible frequency range of the power circuit (18) operationally by activating the corresponding inverter (50) (52) (54) (60) (62) line in the power circuit by activating the operating single-switch partial resonance heating mode (102); in case of the control circuit (14) detects a single load on the hob where the control circuit detects that the output power in the power circuit (14) is less than a predetermined power value, the control circuit (14) initiate the control circuit (14) at a value below the audible frequency value of the power circuit (18) by activating the relevant inverter (44) (46) (48) (50) (52) (54) line in the power circuit by activating a working half-bridge series resonance switched heating mode (112). - A power and control circuit control method of an induction hob in accordance with

Claim 1 , wherein the coils (38) in the power circuit (18) in which the single-switch partial resonance heating (102) is activated, operate without being connected to each other.

3- A power and control circuit control method for an induction hob according to claims 1- 2, wherein each semiconductor switch (44) (46) (50) (52) (60) (62) in the partial resonance switch group (66) in the power circuit (18) where the single-switch partial resonance magnetic heating (102) is engaged operates as a switch or controlled diode.

4- A power and control circuit control method for an induction hob according to Claim 1 , wherein each heater group coil (38) in the power circuit (18) in the activated halfbridge series resonance switched magnetic heating (112) operates at the same frequency value.

5- A control method for the power and control circuit for an induction hob according to claim 1 , wherein each partial resonance switch assembly (66) in the operatively tuned power circuit (18) connected to the DC power supply (24) is on the downstream of the heater assembly (40).

6- A power and control circuit control method for an induction hob according to claim 1 , wherein each partial resonance switch assembly (66) in the operationally tuned power circuit (18) connected to the AC power supply (22) is upstream of the heater assembly (40).

7- A power and control circuit control method for an induction hob according to claims 1- 6, wherein the operably configured power circuit (18) connected to the AC power source (22) connected to each semiconductor switch (44) (46) (50) (52) (60) (62) comprises at least one free pass diode (32) and at least one capacitor (28) connected in parallel resonance.