EP2586271B1 - Cooker hob device - Google Patents

Description

The invention relates to a hob device according to the preamble of claim 1.

From the publication WO 2007/042318 A1 For example, a cooktop apparatus is known which has a switching unit formed as a bipolar transistor with an insulated gate electrode (called IGBT hereinafter) and a control unit. For a discharge of a link capacitor, the control unit controls the IGBT so that the IGBT is not completely turned on and goes into a linear operation mode.

The object of the invention is in particular to provide a generic device with improved properties in terms of high efficiency. The object is achieved by the features of claim 1, while advantageous embodiments and modifications of the invention can be taken from the dependent claims.

The invention is based on a cooktop device, in particular an induction cooktop device, with at least one switching unit and at least one control device.

It is proposed that the control device is provided to automatically cause at least one operating operation that at least the switching unit switches in at least one entire first time interval with at least one changing in its value switching parameter, the switching parameter is constantly changing and / or as time-dependent function has at most stages that are at most 30% of its value. A "switching unit" is to be understood in particular as a unit which is provided for producing and interrupting at least one electrically conductive contact, wherein the unit preferably has at least one transistor and / or at least one IGBT. A "control device" is to be understood in particular as an electronic unit which is provided for controlling at least one operating sequence, the unit preferably having at least one arithmetic unit and / or a memory unit and / or a stored operating program. Under "provided" should be understood in particular specially designed and / or specially equipped and / or specially programmed. By the fact that the control device is intended to "automatically" cause the switching unit to switch with a changing switching parameter, it should be understood in particular that the control device is intended to change the switching parameter with which, independently of intervention by a user the switching unit switches to cause, the control device preferably being arranged to cause a change of the switching parameter, while a cooking zone, which is heated using the switching unit, is operated at a constant cooking level. A "switching" of a switching unit should in particular be understood to mean the manufacture and / or interruption of at least one electrically conductive contact. Under the fact that the switching unit switches in at least one "entire" time interval with a changing switching parameter, should be understood in particular that the time interval is free of time periods, during the entire duration of the switching parameter assumes a constant value. With an embodiment according to the invention, a high efficiency can be achieved. In particular, a flexible influencing of a current flowing through a heating element can be achieved. In particular, it can be achieved that an envelope of a current flowing through the heating element is rapidly increased or reduced to zero within a time period that is spaced apart from minima of a rectified mains voltage that causes a current flow through the heating element in the operating process. that a noise development is at least largely avoided, which results from unsteady changing currents that flow through the heating element and cause a noisy tightening a cookware element.

It is further proposed that the control device is provided to cause the switching unit to be inactive during a total inactivity time interval of at least one millisecond, which immediately adjoins the first time interval. Under an "inactivity" of the switching unit is to be understood in particular a complete omission of switching operations. Under that, that Inactivity time interval "immediately" adjacent to the first time interval, should be understood in particular that a starting point or an end point of the inactivity time interval is identical to an end point or starting point of the first time interval. This allows a high degree of flexibility can be achieved. In particular, a gentle switching of a switching element, which is conductively connected to the switching unit, can be achieved during the inactivity interval.

Preferably, the control device is provided to switch the switching unit in the operating process such that the value of the switching parameter changes substantially continuously in a second time interval, which immediately adjoins the inactivity time interval. In this way, an effective influencing of a current flowing through the heating element can be achieved. In particular, a low-noise operation of the heating element can be achieved while the heating element heats a cookware element.

It is also proposed that the control device is provided to switch at least one switching element, which is electrically conductively connected to the switching unit in at least one operating state, during the inactivity time interval. As a result, a gentle switching of the switching element can be achieved. In particular, it can be achieved that a contact of the switching element is made and / or interrupted while no current flows through the contact.

It is also suggested that a total duration of the first time interval is about two milliseconds. By the fact that the total duration amounts to "approximately" two milliseconds, it should be understood in particular that the total duration differs by at most 80%, preferably by at most 50% and particularly preferably by at most 10% of two milliseconds. Thereby, an efficient operation of the heating element can be achieved. In particular, it can be achieved that the envelope of the current flowing through the heating element is lowered rapidly and quietly or increased to a finite value.

Preferably, the control device is provided to switch the switching unit with an at least substantially constant value of the switching parameter during an entire further time interval, which immediately precedes the first time interval. By the fact that the control device is intended to switch the switching unit with an "at least substantially constant value of the switching parameter" during a whole further time interval, it should be understood in particular that the control device is intended to supply the switching unit during the entire further time interval switch and the switching parameter thereby assumes only values which differ from each other at most 30%, preferably at most 10% and more preferably at most 2%. As a result, a simple mode of operation can be achieved.

Furthermore, it is proposed that the control device is provided to set different lengths of the further time interval for setting a heating power. In this way, a flexible heating can be achieved. In particular, a simple and low-noise setting of low heat outputs can be achieved.

It is also proposed that the switching unit in the operation current to an operation of at least one cooking zone directs and the control device is provided to operate in the operating process, the cooking zone at least during the first time interval on a single cooking stage. A "cooking level" is understood in particular to mean a value set and displayed by a user which symbolizes an average heating power and / or an average temperature with which a cookware element arranged on a cooking zone is heated. As a result, a flexible heating can be achieved. In particular, it can be achieved that an inverter, which has at least one IGBT, supplies current for simultaneous heating operations of two heating elements which heat different cookware elements.

It is also suggested that the switching parameter is a frequency. This allows a simple operation can be achieved. In particular, a simple influencing of a current flowing through the heating element can be achieved.

Furthermore, it is proposed that the switching unit has at least one IGBT and the control device is provided to completely switch on the IGBT during the first time interval. As a result, a high efficiency can be achieved.

In addition, it is proposed that the control device is provided to cause in the operating process that at least temporarily a current caused by a rectified AC power voltage current flows through the switching unit and that the first time interval is temporally spaced from all minima of the rectified AC mains voltage. This allows a high degree of flexibility can be achieved. In particular, a flexible temporal relation of the first time interval to the minima of the rectified AC mains voltage can be achieved.

Furthermore, a cooking hob is proposed with a Kochmuldenvorrichtung, whereby a high efficiency can be achieved.

Furthermore, a cooktop operating method, in particular for operating a cooktop device, is proposed, in which a control device automatically causes at least one switching unit to switch in at least one entire first time interval with at least one switching parameter that changes substantially at least in its value. As a result, high efficiency can be achieved.

Further advantages emerge from the following description of the drawing. In the drawing, an embodiment of the invention is shown. The drawing, the description and the claims contain numerous features in combination.

Fig. 1

eine Draufsicht auf eine Kochmulde mit einer erfindungsgemäßen Kochmuldenvorrichtung,

Fig. 2

eine Schaltung der Kochmuldenvorrichtung,

Fig. 3

eine schematische Darstellung einer Spannung, welche an einem Kondensator der Schaltung anliegt, und einer gleichgerichteten Stromnetzwechselspannung und einer Hüllkurve eines Stroms, der durch Heizelemente der Schaltung fließt, wobei entlang einer Abszisse die Zeit aufgetragen ist, und

Fig. 4

eine schematische Darstellung einer Periodendauer und einer Schaltfrequenz, mit welcher eine Schalteinheit der Schaltung schaltet, wobei entlang einer Abszisse die Zeit aufgetragen ist.

Show it:

Fig. 1

a top view of a cooking hob with a hob according to the invention,

Fig. 2

a circuit of the cooktop device,

Fig. 3

a schematic representation of a voltage applied to a capacitor of the circuit, and a rectified AC mains voltage and an envelope of a current flowing through heating elements of the circuit, wherein along an abscissa the time is plotted, and

Fig. 4

a schematic representation of a period and a switching frequency at which switches a switching unit of the circuit, wherein along an abscissa, the time is plotted.

FIG. 1 shows a plan view of a cooking hob with a cooking hob device according to the invention, designed as an induction cooker device, which has a plurality of cooking zones 34. A circuit 36 ( FIG. 2 ) of the cooktop device has four coils formed as heating elements L ₁ , L ₂ , L ₃ , L ₄ , which are all simultaneously operated at different power levels. Each of the heating elements L ₁ , L ₂ , L ₃ , L ₄ is assigned to exactly one of the cooking zones 34, so that when using the cooktop each of the heating elements L ₁ , L ₂ , L ₃ , L ₄ exactly one cookware element, ie z. As a pot or pan, heated. The circuit 36 has a switching device 10, which has a first and a second switching unit 28, 30. The first switching unit 28 is formed by a first inverter 28 'and the second switching unit 30 is formed by a second inverter 30'. The first inverter 28 'includes a first insulated gate bipolar transistor (hereinafter abbreviated to "IGBT") 32 and a second IGBT 33. In addition, the inverter 30 'has a first IGBT 44 and a second IGBT 46.

Furthermore, the circuit 36 has a country-specific AC voltage source U, which provides a mains AC voltage with an effective value of 230 V and a frequency of 50 Hz. The described hob device is intended in particular for operation in Germany. For cooktop appliances intended for US operation, a corresponding AC power source provides a 60 Hz power line voltage. The voltage of AC power source U first passes through a filter 40 of circuit 36, which eliminates high frequency noise and is essentially a low pass filter. A voltage filtered by the filter 40 is rectified by a rectifier 42 of the circuit 36, which may be designed as a bridge rectifier, so that at a output of the rectifier 42 is a rectified voltage U _g ( _FIG. FIG. 3 ) which is applied between a collector of the IGBT 32 and an emitter of the IGBT 33. The rectified voltage U _g is further to between a collector of the IGBT 44, and at an emitter of the IGBT 46th Furthermore, the circuit 36 has two capacitors C ₁ , C ₂ . In each case a first contact of the capacitors C ₁ , C ₂ is conductive connected to the collector of the IGBT 32 and conductively connected to a collector of the IGBT 44. Furthermore, in each case a second contact of the capacitors C ₁ , C _{2 is} conductively connected to the emitter of the IGBT 33 and conductively connected to the emitter of the IGBT 46. An emitter of the IGBT 32 is conductively connected to a collector of the IGBT 33. In addition, an emitter of the IGBT 44 is conductively connected to a collector of the IGBT 46.

Furthermore, the circuit 36 as a relay S ₁ 'trained switching element S ₁ and five other relays S ₂ , S ₃ , S ₄ , S ₅ , S ₆ on. The relays S ₁ ', S ₂ , S ₃ , S ₄ , S ₅ , S ₆ are SPDT relay and identical. Each of the relays S ₁ ', S ₂ , S ₃ , S ₄ , S ₅ , S ₆ has a first, a second and a third contact and a coil, wherein the first contacts by a corresponding control of the coil optionally with the second or the third contact is conductively connected.

The first contact of the relay S ₃ is conductively connected to the emitter of the IGBT 32. Further, the second contact of the relay S _{3 is} connected to the first contact of the relay S ₁ '. The third contact of the relay S ₃ is conductively connected to the first contact of the relay S ₂ . The second contact of the relay S ₁ 'is conductively connected to a first contact of the heating element L ₁ . The third contact of the relay S ₁ 'is conductively connected to a first contact of the heating element L ₂ . The second contact of the relay S ₂ is conductively connected to a first contact of the heating element L ₃ . The third contact of the relay S ₂ is conductively connected to a first contact of the heating element L ₄ .

In addition, the first contact of the relay S _{6 is} conductively connected to the emitter of the IGBT 44. Further, the second contact of the relay S _{6 is} connected to the first contact of the relay S ₄ . The third contact of the relay S ₆ is conductively connected to the first contact of the relay S ₅ . The second contact of the relay S ₄ is conductively connected to a first contact of the heating element L ₁ . Further, the third contact of the relay S _{4 is} conductively connected to a first contact of the heating element L ₂ . The second contact of the relay S ₅ is conductively connected to a first contact of the heating element L ₃ . The third contact of the relay S ₅ is conductively connected to a first contact of the heating element L ₄ .

A second contact of the heating element L ₁ is conductively connected to a second contact of the heating element L ₂ . Further, a second contact of the heating element L _{3 is} conductively connected to a second contact of the heating element L ₄ . The circuit 36 also has capacitors C ₃ , C ₄ , C ₅ , C ₆ . The second contact of the heating element L ₁ is conductive with a first contact of the capacitor C ₃ and connected to a first contact of the capacitor C ₄ . The second contact of the heating element L ₃ is conductive to a first contact of the capacitor _C5 and connected to a first contact of the capacitor C. ₆ Second contacts of the capacitors C ₃ and C ₅ are conductively connected to the collector of the IGBT 32. Further, second contacts of the capacitors C ₄ and C _{6 are} conductively connected to the emitter of the IGBT 46.

Both by means of the IGBT 32 and by means of the IGBT 33 is in each case a power supply to the first switching element S ₁ , through which in an operating process, a generated by means of the AC voltage source U current flows, producible and interruptible. First, the relays S ' ₁ , S ₂ , S ₃ , S ₄ , S ₅ and S ₆ in the operation in the following switching states: In the relay S' ₁ , S ₂ , S ₃ , S ₄ , S ₅ is respectively the first contact conductively connected to the second contact. In the relay S ₆ , the first contact with the third contact is conductively connected.

A control device 14 of the circuit 36, which has two control units 56, 58, controls the switching device 10 during the operating process. For this purpose, the control device 14 is connected to the switching device 10 and in particular to the gate terminals of the IGBTs 32, 33, 44, 46 ( not shown).

The control device 14 causes the heating elements L1 and L2 and thus also those cooking zones 34 associated with the heating elements L1 and L2 to be operated on a single cooking stage during the entire operating process and to be supplied alternately by the inverter 28 '. In the operation, the IGBTs 44, 46 are inactive. During the operating procedure, the control device 14 causes the inverter 28 'to operate automatically during a first time interval t ₁ (FIG. FIG. 3 ) switches in the entire first time interval t ₁ with a switching parameter which changes substantially in value 15. The switching parameter is a frequency 31 ( FIG. 4 ), namely a switching frequency at which the inverter 28 'switches. During a period 39, which is one divided by the frequency 31, the IGBT 32 completely turns on exactly once so that there is a conductive connection between the emitter and the collector of the IGBT 32. This switching of the IGBT 32 is initiated by the control device 14. Further, the IGBT 32 interrupts this conductive connection during the period 39 exactly once. During the period 39, the IGBT 33 completely turns on exactly once, so that a conductive connection between the emitter and the collector of the IGBT 33 consists. This switching of the IGBT 33 is initiated by the control device 14. Further, the IGBT 33 interrupts this conductive connection during the period 39 exactly once. During the period is precisely at any time of the period 39 exactly one of the IGBTs 32, 33 connected such that there is a conductive connection between its collector and its emitter. The first time interval t ₁ is two milliseconds long. Inverter 28 'conducts current to heat the heating elements L1 and L2 during the operation.

Further, in the operation, the controller 14 causes the inverter 28 'to be inactive during a total inactivity time interval t _ln immediately following the first time interval t ₁ , such that during the entire inactivity time interval a conductive connection between the collector and the emitter of the IGBT 32 is interrupted and a conductive connection between the collector and the emitter of the IGBT 33 is interrupted. The inactivity time interval t _ln is more than two milliseconds. During the inactivity time interval, the relay S1 'is switched, so that after switching the first contact with the third contact of the relay S1' is conductively connected to each other. This causes energy to be supplied to the heating element L1 prior to the inactivity time interval _tIn , and energy to be supplied to the heating element L2 after the inactivity time interval _tIn by an activity of the inverter 28 '.

Furthermore, the control device 14 switches the inverter 28 'during the operating process in such a way that the switching frequency of the inverter 28' essentially continuously during a time interval t ₂ (FIG. FIGS. 3 and 4 ) changes. The time interval t ₂ immediately follows the inactivity time interval t _ln . By switching of the inverter 28 'in the time intervals t ₁ and t ₂ is flowing, an envelope 48 of a current before the inactivity time interval _ln t by the heating element L1 flows and after the period of inactivity interval _ln t by the heating element L2, during the time intervals t ₁ and t _{2 is} rapidly reduced or increased, thereby avoiding noises which occur in the event of an abrupt change in the current and which are caused by forces which occur due to the abrupt change and which act on set-up cookware elements.

The control device further causes, during the operation, to switch the inverter 28 'at a constant frequency 31 during a total time interval t _v becomes ( FIG. 3 ). The time interval t _v immediately precedes the time interval t ₁ . The controller 14 causes a quotient given by the period during a period 39 during which the IGBT 32 is turned on divided by the period 39 to be constant while the time intervals t ₁ , t _v and t _{2 are} constant.

In FIG. 3 is a rectified, supplied by the AC voltage source U in the operation process AC mains voltage 37 is shown. The AC mains voltage 37 temporarily causes a rush current through the inverter 28 'during the operation. The first time interval t ₁ is temporally spaced from all minima 38 of the rectified AC mains voltage 37.

A maximum value of the frequency 31 is during the time interval t ₁ at about 200 kHz. A value of the frequency 31 may be between 30 kHz and 75 kHz during the time interval t _v . During the first time interval t ₁ , the period duration 39 decreases stepwise in several stages by the same amount of time T _dec (in FIG FIG. 4 not visible). A width of the stages is (T _max -i T _dec ) / 30 MHz, where T _{max is} a maximum period duration 39 in the time interval t _v and i is a numbering of the stages in their chronological order. During the second time interval t ₂ , the period duration 39 increases in stages in a plurality of stages by the same amount of time each time, which may differ from the aforementioned amount of time (in FIG FIG. 4 not visible), wherein the width of these stages (T _max1 -i T _inc ) / 30 MHz and T _{max1 is} a value of the period 39 immediately after the second time interval t ₂ and i is a numbering of the stages in their time sequence and T _{inc is} a height of the steps that may differ from T _dec . Furthermore, a minimum value of the period duration 39 in the time interval t ₁ may differ from a minimum value of the period duration 39 during the time interval t ₂ .

During a time interval immediately following the time interval t ₂ , the inverter is operated at a constant frequency. After this time interval, as already described, the relay S1 'is switched again and that part of the operating procedure which has already been described is repeated.

In principle, it is conceivable that the inverter 30 'is also temporarily active during the operating process.

In a further operation, which differs from the above-described operation only in that a switching of the switching element S _{1 is} omitted and the heating element L _{1 is operated} at different cooking levels, ie with different heating powers, the different cooking levels are adjusted by lengths of the time interval t _v and / or the time interval t _{ln are changed} by the control device. In principle, it is conceivable that the time interval t _{1 is} omitted and an end point of the time interval t _{v is} identical to a minimum of the rectified power supply AC voltage. In principle, it is also conceivable that in the further operation, the heating element L _{1 is operated} on a single cooking stage.

Furthermore, it is conceivable that instead of a half-bridge circuit, as in FIG. 2 shown, a full-bridge circuit or instead of the inverter 28 ', a single-transistor inverter is used. reference numeral 10 switching device L ₁ heating element 14 control device L ₂ heating element 15 value L ₃ heating element 28 switching unit L ₄ heating element 28 ' inverter U AC voltage source 30 switching unit 30 ' inverter U _g tension 31 frequency C ₁ capacitor 32 IGBT C ₂ capacitor 33 IGBT C ₃ capacitor 34 cooking zone C ₄ capacitor 36 circuit C ₅ capacitor 37 Mains AC voltage C ₆ capacitor 38 minima S ₁ switching element 39 period S ₁ ' relay 40 filter S ₂ relay 42 rectifier S ₃ relay 44 IGBT S ₃ ' switching element 46 IGBT S ₄ relay 48 envelope S ₅ relay 56 control unit S ₆ relay 58 control unit t ₁ time interval t _in Inactivity time interval t ₂ time interval t _v time interval

Claims (13)

1. Cooktop apparatus, in particular an induction cooktop apparatus, having at least one switching unit (28, 30) and at least one control apparatus (14),
   characterised in that
   the control apparatus (14) is provided to prompt at least the switching unit (28, 30) automatically in at least one operating cycle to switch in at least one entire first time interval (t₁) using at least one switching parameter, the value (15) of which changes, wherein the switching parameter changes continuously and/or viewed as a time-dependent function has at most stages which amount at most to 30% of its value.
2. Cooktop apparatus according to claim 1,
   characterised in that
   the control apparatus (14) is provided to bring about inactivity of the switching unit (28, 30) during an entire inactivity time interval (t_in) that is at least one millisecond long during the operating cycle, said inactivity time interval (t_in) directly adjoining the first time interval (t₁).
3. Cooktop apparatus according to claim 2,
   characterised in that
   the control apparatus (14) is provided to switch the switching unit (28, 30) during the operating cycle so that the value of the switching parameter changes substantially continuously in a second time interval (t₂) that directly adjoins the inactivity time interval (t_in).
4. Cooktop apparatus according to one of claims 2 or 3,
   characterised in that
   the control apparatus (14) is provided to switch at least one switching element (S₁) configured as a relay (S₁'), which is connected to the switching unit (28, 30), which has at least one transistor and/or at least one IGBT, in an electrically conducting manner in at least one operating state, during the inactivity time interval (t_in).
5. Cooktop apparatus according to one of the preceding claims,
   characterised in that
   an overall duration of the first time interval (t₁) is around two milliseconds.
6. Cooktop apparatus according to one of the preceding claims,
   characterised in that
   the control apparatus (14) is provided to switch the switching unit (28, 30) during an entire further time interval (t_v), which directly precedes the first time interval (t₁), using an at least substantially constant value of the switching parameter.
7. Cooktop apparatus according to claim 6,
   characterised in that
   the control apparatus (14) is provided to set different lengths for the further time interval (t_v) for setting a heat output.
8. Cooktop apparatus according to one of the preceding claims,
   characterised in that
   the switching unit (28, 30) conveys current for operation of at least one cooking zone (34) during the operating cycle and the control apparatus (14) is provided to operate the cooking zone (34) at a single heat setting at least during the first time interval (t₁) during the operating cycle.
9. Cooktop apparatus according to one of the preceding claims,
   characterised in that
   the switching parameter is a frequency (31).
10. Cooktop apparatus according to one of the preceding claims,
    characterised in that
    the switching unit (28, 30) has at least one IGBT (32, 33, 44, 46) and the control apparatus (14) is provided to enable the IGBT (32, 33, 44, 46) fully during the first time interval (t₁).
11. Cooktop apparatus according to one of the preceding claims,
    characterised in that
    the control apparatus (14) is provided to cause a current produced by a rectified power network alternating current voltage (37) to flow at least temporarily through the switching unit (28, 30) during the operating cycle and the first time interval (t₁) is temporally distanced from all minima (38) of the rectified power network alternating current voltage (37).
12. Cooktop having a cooktop apparatus according to one of claims 1 to 11.
13. Cooktop operating method, in particular for operating a cooktop apparatus according to one of claims 1 to 11, in which a control apparatus (14) automatically prompts at least one switching unit (28, 30) to switch in at least one entire first time interval (t₁) using at least one switching parameter, the value of which at least changes, wherein the switching parameter changes continuously and/or viewed as a time-dependent function has at most stages which amount at most to 30% of its value.

Images