CN106851881B - Electromagnetic heating system and heating control device thereof - Google Patents
Electromagnetic heating system and heating control device thereof Download PDFInfo
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- CN106851881B CN106851881B CN201510895322.1A CN201510895322A CN106851881B CN 106851881 B CN106851881 B CN 106851881B CN 201510895322 A CN201510895322 A CN 201510895322A CN 106851881 B CN106851881 B CN 106851881B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention discloses an electromagnetic heating system and a heating control device thereof, wherein the device comprises: a resonant circuit; a power supply circuit; a power switching tube; the signal generation circuit is used for generating a self-oscillation starting signal; the signal modulation circuit is connected with the signal generation circuit and is used for outputting a driving signal according to the vibration starting signal and the reference signal; the signal amplifying circuit is respectively connected with the signal modulating circuit and the control electrode of the power switch tube and is used for amplifying the driving signal so as to drive the power switch tube to be turned on or turned off through the amplified driving signal; and the synchronous feedback circuit is respectively connected with the resonant circuit and the signal generation circuit and is used for adjusting the oscillation starting signal according to the resonant state of the resonant circuit. Therefore, the device can build a resonant circuit through the minimum control feedback loop, has a simple circuit structure and a simple control process, and is stable and reliable.
Description
Technical Field
The invention relates to the technical field of household appliances, in particular to a heating control device of an electromagnetic heating system and the electromagnetic heating system.
Background
The electromagnetic heating circuit in the related art generally has the following problems:
firstly, the circuit control process is complex, current sampling is needed through software, then the sampled current is amplified through an amplifier, and then the internal constant power calculation of the software is carried out according to the amplified sampled current. However, the accuracy of the current sampling element adopted in the related art is not high enough, which often leads to larger current sampling deviation, and further leads to larger deviation of the constant power calculation result, and the output power and the power deviation cannot be effectively controlled.
Secondly, the circuit system is complex, and the related technology needs to sample different signals, so that the feedback loop can complete the basic structure construction of the main control loop.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, an object of the present invention is to propose a heating control device for an electromagnetic heating system, which allows to build up a resonant circuit with a minimum of control feedback loops, with a simple and elegant circuit design.
Another object of the present invention is to propose an electromagnetic heating system.
In order to achieve the above object, an embodiment of an aspect of the present invention provides a heating control device of an electromagnetic heating system, including: a resonant circuit; the power supply circuit is connected with the input end of the resonant circuit to supply power for the resonant circuit; the collector of the power switch tube is connected with the output end of the resonant circuit, and the emitter of the power switch tube is grounded; a signal generation circuit for generating a self-oscillating start signal; the signal modulation circuit is connected with the signal generation circuit and is used for outputting a driving signal according to the vibration starting signal and the reference signal; the signal amplification circuit is respectively connected with the signal modulation circuit and the control electrode of the power switch tube and is used for amplifying the driving signal so as to drive the power switch tube to be turned on or turned off through the amplified driving signal; and the synchronous feedback circuit is respectively connected with the resonant circuit and the signal generation circuit and is used for adjusting the oscillation starting signal according to the resonance state of the resonant circuit.
According to the heating control device of the electromagnetic heating system, the signal generating circuit generates the self-oscillation starting signal to control the resonant circuit to automatically resonate, the signal modulating circuit outputs the driving signal according to the starting signal and the reference signal to adjust the output power of the resonant circuit, and the synchronous feedback circuit is used for adjusting the starting signal according to the resonant state of the resonant circuit to form closed-loop negative feedback. Therefore, the device can build a resonant circuit through the minimum control feedback loop, has a simple circuit structure and a simple control process, and is stable and reliable.
According to some embodiments of the invention, the signal generating circuit comprises: the power supply end of the first comparator is connected with a preset power supply, and the ground of the first comparator is grounded; one end of the first resistor is connected with a preset power supply; one end of the second resistor is connected with the other end of the first resistor, the other end of the second resistor is connected with the output end of the first comparator, a sixth node is arranged between the second resistor and the first resistor, and the sixth node is connected with the positive input end of the first comparator; one end of the first capacitor is connected with the negative input end of the first comparator, the other end of the first capacitor is grounded, and the negative input end of the first comparator is used as the output end of the signal generating circuit and is connected with the signal modulating circuit; one end of the third resistor is respectively connected with one end of the first capacitor and the negative input end of the first comparator; one end of the fourth resistor is connected with the other end of the third resistor, and the other end of the fourth resistor is connected with the preset power supply; the anode of the first diode is connected with the other end of the third resistor and one end of the fourth resistor respectively, and the cathode of the first diode is connected with the output end of the first comparator.
When the first comparator outputs a high-level signal, the first capacitor, the third resistor and the fourth resistor form a charging loop; when the first comparator outputs a low level, the first capacitor, the third resistor and the first diode form a discharge loop.
According to some embodiments of the invention, the signal modulation circuit comprises: one end of the resonant switch is connected with a preset power supply; one end of the fifth resistor is connected with the other end of the resonant switch; one end of the sixth resistor is connected with the other end of the fifth resistor, and the other end of the sixth resistor is grounded, wherein a first node is arranged between the fifth resistor and the sixth resistor; the anode of the third diode is connected with one end of the fifth resistor and the other end of the resonant switch; a seventh resistor, one end of which is connected with the cathode of the third diode; one end of the eighth resistor is connected with the other end of the seventh resistor, and the other end of the eighth resistor is grounded, wherein a second node is arranged between the eighth resistor and the seventh resistor; the emitter of the first triode is connected with the second node, the collector of the first triode is grounded, and the base of the first triode is connected with the first node; a ninth resistor, one end of which is connected with the second node; a fourth diode connected in parallel with the ninth resistor; the positive electrode of the electrolytic capacitor is connected with the other end of the ninth resistor, and the negative electrode of the electrolytic capacitor is grounded, wherein a third node is arranged between the electrolytic capacitor and the ninth resistor and is used for providing the reference signal; the positive input end of the second comparator is connected with the third node, the negative input end of the second comparator is used as the input end of the signal modulation circuit to be connected with the output end of the signal generation circuit, the output end of the second comparator is used as the output end of the signal modulation circuit to be connected with the signal amplification circuit, the power end of the second comparator is connected with a preset power supply, and the ground of the second comparator is grounded.
When the resonant switch is disconnected, the resonant circuit is in a stop working state; when the resonant switch is closed, the resonant circuit is in a working state.
When the resistance value of the eighth resistor is fixed, the reference signal and the resistance value of the seventh resistor are in negative correlation, and the turn-on time of the power switch tube and the output power of the resonant circuit are also in negative correlation with the resistance value of the seventh resistor.
Or when the resistance value of the seventh resistor is fixed, the reference signal and the resistance value of the eighth resistor are in positive correlation, and the on time of the power switch tube and the output power of the resonant circuit are in positive correlation with the resistance value of the eighth resistor.
According to some embodiments of the invention, the synchronization feedback circuit comprises: a tenth resistor, one end of which is connected with the input end of the resonant circuit; an eleventh resistor, wherein one end of the eleventh resistor is connected with the other end of the tenth resistor, the other end of the eleventh resistor is grounded, and a fourth node is arranged between the tenth resistor and the eleventh resistor; a twelfth resistor, wherein one end of the twelfth resistor is connected with one end of the power switch tube; a thirteenth resistor, one end of which is connected with the other end of the twelfth resistor, the other end of which is grounded, and a fifth node is arranged between the twelfth resistor and the thirteenth resistor; and the positive input end of the third comparator is connected with the fourth node, the negative input end of the third comparator is connected with the fifth node, and the output end of the third comparator is connected with the output end of the first comparator.
According to some embodiments of the invention, the signal amplifying circuit includes a push-pull circuit composed of a second transistor and a third transistor.
In order to achieve the above objective, another embodiment of the present invention further provides an electromagnetic heating system, which includes a heating control device of the electromagnetic heating system.
According to the electromagnetic heating system provided by the embodiment of the invention, the resonant circuit can be built through the minimum control feedback loop, the circuit structure is simple, and the control process is simple.
Drawings
FIG. 1 is a block schematic diagram of a heating control device of an electromagnetic heating system according to an embodiment of the present invention;
FIG. 2 is a schematic circuit diagram of a heating control device of an electromagnetic heating system according to one embodiment of the invention;
fig. 3 and 4 are schematic waveforms of a signal generating circuit according to an embodiment of the present invention; and
fig. 5 and 6 are waveform diagrams of a signal modulation circuit according to an embodiment of the present invention.
Reference numerals:
a resonance circuit 10, a power supply circuit 20, a power switching tube 30, a signal generating circuit 40, a signal modulating circuit 50, a signal amplifying circuit 60 and a synchronous feedback circuit 70;
a heating coil L1 and a resonance capacitor C1;
the first comparator U1, the first resistor R1, the second resistor R2, the first capacitor C1, the third resistor R3, the fourth resistor R4, the first diode D1 and the second diode D2;
the device comprises a resonant switch K1, a fifth resistor R5, a sixth resistor R6, a third diode D3, a seventh resistor R6, an eighth resistor R8, a first triode Q1, a ninth resistor R9, a fourth diode D4, an electrolytic capacitor EC and a second comparator U2;
a second transistor Q2 and a third transistor Q3.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
A heating control device of an electromagnetic heating system and an electromagnetic heating system having the same according to embodiments of the present invention are described below with reference to the accompanying drawings.
Fig. 1 is a block schematic diagram of a heating control device of an electromagnetic heating system according to an embodiment of the present invention. As shown in fig. 1, the heating control device includes: the power supply circuit comprises a resonance circuit 10, a power supply circuit 20, a power switching tube 30, a signal generating circuit 40, a signal modulating circuit 50, a signal amplifying circuit 60 and a synchronous feedback circuit 70.
Wherein, the resonant circuit 10 may include a heating coil L1 and a resonant capacitor C1, and the heating coil L1 and the resonant capacitor C1 may be connected in parallel to constitute a parallel resonant circuit; the power supply circuit 20 is connected to an input end of the resonant circuit 10 to supply power to the resonant circuit 10, and specifically, the power supply circuit 20 may perform rectifying and filtering processing on external ac power to output dc power to the resonant circuit 10; the collector of the power switch tube 30 is connected with the output end of the resonant circuit 10, and the emitter of the power switch tube 30 is grounded.
The signal generating circuit 40 is used for generating a self-oscillation starting signal; the signal modulation circuit 50 is connected with the signal generation circuit 40, and the signal modulation circuit 50 is used for outputting a driving signal according to the oscillation starting signal and the reference signal; the signal amplifying circuit 60 is respectively connected with the signal modulating circuit 50 and the control electrode of the power switch tube 30, and the signal amplifying circuit 60 is used for amplifying the driving signal so as to drive the power switch tube 30 to be turned on or turned off through the amplified driving signal; the synchronous feedback circuit 70 is connected to the resonant circuit 10 and the signal generating circuit 40, respectively, and the synchronous feedback circuit 70 is used for adjusting the oscillation starting signal according to the resonant state of the resonant circuit 10.
Specifically, after the heating control device is powered on, the signal generating circuit 40 may output a vibration starting signal that varies according to a preset rule, the signal modulating circuit 50 compares the vibration starting signal with a reference signal to output a driving signal, the frequency of the driving signal is related to the reference signal, and then the signal amplifying circuit 60 may drive the power switching tube 30 to be turned on or off according to the amplified driving signal, so that the output power of the resonant circuit 10 can be controlled by controlling the on time of the power switching tube 30, the longer the on time is, the larger the output power is, and conversely, the shorter the on time is, the smaller the output power is. In addition, the synchronous feedback circuit 70 also collects the resonance state of the resonance circuit 10 in real time, and adjusts the oscillation starting signal according to the resonance state, so as to form closed-loop negative feedback, so that the oscillation starting signal continuously changes according to a preset rule, and the output power is kept stable.
Therefore, the heating control device of the electromagnetic heating system provided by the embodiment of the invention generates the self-oscillation starting signal through the signal generating circuit to control the resonant circuit to automatically resonate, the signal modulating circuit outputs the driving signal according to the starting signal and the reference signal to adjust the output power of the resonant circuit, and the synchronous feedback circuit is used for adjusting the starting signal according to the resonant state of the resonant circuit to form closed-loop negative feedback. Therefore, the device can build a resonant circuit through the minimum control feedback loop, has a simple circuit structure and a simple control process, and is stable and reliable.
The circuit structure and the operation principle of the heating control device according to the embodiment of the present invention are described in detail below with reference to fig. 2 to 6.
According to one embodiment of the present invention, as shown in fig. 2, the signal generating circuit 40 includes: the first comparator U1, the first resistor R1, the second resistor R2, the first capacitor C1, the third resistor R3, the fourth resistor R4 and the first diode D1.
The power end of the first comparator U1 is connected with a preset power supply VCC, and the ground end of the first comparator U1 is grounded; one end of the first resistor R1 is connected with a preset power supply VCC; one end of the second resistor R2 is connected with the other end of the first resistor R1, the other end of the second resistor R2 is connected with the output end of the first comparator U1, a sixth node is arranged between the second resistor R2 and the first resistor R1, and the sixth node is connected with the positive input end of the first comparator U1; one end of the first capacitor C1 is connected with the negative input end of the first comparator U1, the other end of the first capacitor C1 is grounded, and the negative input end of the first comparator U1 is used as the output end of the signal generating circuit 40 to be connected with the signal modulating circuit 50; one end of the third resistor R3 is respectively connected with one end of the first capacitor C1 and the negative input end of the first comparator U1; one end of the fourth resistor R4 is connected with the other end of the third resistor R3, and the other end of the fourth resistor R4 is connected with a preset power supply VCC; the anode of the first diode D1 is connected with the other end of the third resistor R3 and one end of the fourth resistor R4 respectively, and the cathode of the first diode D1 is connected with the output end of the first comparator U1.
Further, the heating control device further includes: and the anode of the second diode D2 is connected with the output end of the first comparator U1, and the cathode of the second diode D2 is connected with the preset power supply VCC.
When the first comparator U1 outputs a high level signal, the first capacitor C1, the third resistor R3 and the fourth resistor R4 form a charging loop; when the first comparator U1 outputs a low level, the first capacitor C1, the third resistor R3, and the first diode D1 constitute a discharge loop.
The working procedure of the signal generating circuit 40 of the embodiment of the present invention is as follows:
after the heating control device is powered on, the voltage of the positive input end A1 of the first comparator U1 is shown in a line A1 in fig. 3 at time 0-T1, that is, the point A1 is at a high level, the voltage of the negative input end B1 of the first comparator U1 is lower than the voltage of the positive input end A1 of the first comparator U1, and the output end C1 of the first comparator U1 outputs a high level, as shown in a line C1 in fig. 4 at time 0-T1. In the capacitor charging stage, the preset power supply VCC charges the first capacitor C1 through the third resistor R3 and the fourth resistor R4, and the voltage at the negative input terminal B1 of the first comparator U1, that is, one end of the first capacitor C1, is continuously increased, and the voltage waveform is shown in fig. 3 at the time of 0-T1 by the line B1.
At time T1, the voltage of the negative input terminal B1 of the first comparator U1 is higher than the voltage of the positive input terminal A1 of the first comparator U1, the first comparator U1 inverts to output a low level, as shown by the line C1 at time T1-T2 in fig. 4, when the first comparator U1 outputs a low level, the output terminal C1 of the first comparator U1 is shorted to ground according to the characteristics of the comparator, the voltage of the positive input terminal A1 of the first comparator U1 is the divided voltage of the preset power VCC divided by the first resistor R1 and the second resistor R2, as shown by the line A1 at time T1-T2 in fig. 3, and the voltage at the point A1 is V1 volts. Meanwhile, since the output terminal C of the comparator U1 is shorted to ground, the first capacitor C1 discharges to ground through the third resistor R3 and the first diode D1, and the voltage at the negative input terminal B1 of the first comparator U1 continuously decreases, as shown by the line B1 in fig. 3 at the time T1-T2.
At time T2, the discharge of the first capacitor C1 to ground causes the voltage at the negative input terminal B1 of the first comparator U1 to be lower than the voltage at the positive input terminal A1 of the first comparator U1, the first comparator U1 again inverts to output a high level, and the voltage at the output terminal C1 of the first comparator U1 is high level, as shown by the line C1 at time T2-T3 in fig. 4. The voltage at the positive input terminal A1 of the first comparator U1 is at a high level, as shown in a line A1 of fig. 3 at time T2-T3, the preset power source VCC charges the first capacitor C1 through the third resistor R3 and the fourth resistor R4, and the voltage at the negative input terminal B1 of the first comparator U1, i.e. one end of the first capacitor C1, is continuously increased, and the voltage waveform is shown in a line B1 of fig. 3 at time T2-T3.
Repeatedly, the negative input terminal B1 of the first comparator U1, i.e. one end of the first capacitor C1, generates a vibration starting signal shown by the line B in fig. 3.
According to one embodiment of the present invention, as shown in fig. 2, the signal modulation circuit 50 includes: the circuit comprises a resonant switch K1, a fifth resistor R5, a sixth resistor R6, a third diode D3, a seventh resistor R6, an eighth resistor R8, a first triode Q1, a ninth resistor R9, a fourth diode D4, an electrolytic capacitor EC and a second comparator U2.
One end of the resonant switch K1 is connected with a preset power supply VCC; one end of the fifth resistor R5 is connected with the other end of the resonant switch K1; one end of the sixth resistor R6 is connected with the other end of the fifth resistor R5, and the other end of the sixth resistor R6 is grounded, wherein a first node is arranged between the fifth resistor R5 and the sixth resistor R6; the anode of the third diode D3 is connected with one end of the fifth resistor R5 and the other end of the resonance switch K1; one end of the seventh resistor R7 is connected with the cathode of the third diode D3; one end of the eighth resistor R8 is connected with the other end of the seventh resistor R7, and the other end of the eighth resistor R8 is grounded, wherein a second node is arranged between the eighth resistor R8 and the seventh resistor R7; the emitter of the first triode Q1 is connected with the second node, the collector of the first triode Q1 is grounded, the base of the first triode Q1 is connected with the first node, and the first triode Q1 can be a PNP triode; one end of the ninth resistor R9 is connected with the second node; the fourth diode D4 is connected with the ninth resistor R9 in parallel; the positive electrode of the electrolytic capacitor EC is connected with the other end of the ninth resistor R9, and the negative electrode of the electrolytic capacitor EC is grounded, wherein a third node is arranged between the electrolytic capacitor EC and the ninth resistor C9 and is used for providing a reference signal; the positive input end of the second comparator U2 is connected with the third node, the negative input end of the second comparator U2 is used as the input end of the signal modulation circuit 50 to be connected with the output end of the signal generation circuit 40, the output end of the second comparator U2 is used as the output end of the signal modulation circuit 50 to be connected with the signal amplification circuit 60, the power end of the second comparator U2 is connected with the preset power supply VCC, and the ground of the second comparator U2 is grounded.
The resonant switch K1 is used to control the resonant circuit 10 to operate or stop operating. When the resonance switch K1 is turned off, the resonance circuit 10 is in a stop operation state; when the resonant switch K1 is closed, the resonant circuit 10 is in an operating state.
The working procedure of the signal modulation circuit 50 of the embodiment of the present invention is as follows:
after the heating control device is electrified, the resonance switch K1 is in an off state, the voltage of the positive input end A2 of the second comparator U2 is zero, the voltage of the negative input end B2 of the second comparator U2 is the same as the voltage of the negative input end B1 of the first comparator U1, the voltage waveform of the point B2 is shown as a1 in fig. 3 and A2 in fig. 5, the voltage of the negative input end B2 of the second comparator U2 is higher than the voltage of the positive input end A2 thereof, the output end C2 of the second comparator U2 outputs a low level, and the resonance circuit 10 does not work. After the resonant switch K1 is turned on, the base voltage of the first triode Q1 is the voltage division of the fifth resistor R5 and the sixth resistor R6 to the preset power supply VCC, the base is at a high level, the first triode Q1 is in an off state according to the PNP type triode characteristics, the preset power supply VCC charges the electrolytic capacitor EC through the resonant switch K1, the third diode D3, the seventh resistor R7, and the ninth resistor R9, and the voltage at the positive input terminal B2 of the second comparator U2 continuously rises and stabilizes at the voltage V2, as shown by the line B2 in fig. 5, the voltage V2 is a reference signal, and the voltage value of the voltage V is the voltage division of the eighth resistor R8 and the seventh resistor R7 to the preset power supply VCC. At this time, the voltage at the negative input terminal B2 of the second comparator U2 is lower than the voltage V2 at the positive input terminal B2 of the second comparator U2, and the output terminal C3 of the second comparator U2 outputs a high level, as shown in fig. 5 at the time t0-t1 along the line C2. The second comparator U2 outputs a high level, which is amplified by the signal amplifying circuit 60 and drives the power switching tube 30 to turn on, the resonance circuit 10 operates, and the power supply circuit 20 discharges to the ground through the heating coil L1 and the power switching tube 30.
Since the voltage of the negative input terminal B2 of the second comparator U2 is the same as the voltage of the negative input terminal B1 of the first comparator U1, the voltage of the negative input terminal B2 of the second comparator U2 continuously increases after being powered on, as shown by the line a2 in fig. 5, so that when the voltage of the negative input terminal B2 of the second comparator U2 is higher than the voltage V2 of the positive input terminal B2 of the second comparator U2, the second comparator U2 inverts to output a low level, as shown by the line c2 at the time t1-t2 in fig. 5. The second comparator U2 outputs a low level, and the low level drives the power switching tube 30 to turn off after passing through the signal amplifying circuit 60, the heating coil L1 and the resonance capacitor C1 in the resonance circuit 10 start to oscillate, and in one resonance period, charging of the resonance capacitor C1 by the heating coil L1 and discharging of the heating coil L1 by the resonance capacitor C1 are completed.
Thereafter, at time T1 in fig. 3, the voltage of the negative input terminal B1 of the first comparator U1 is higher than the voltage of the positive input terminal A1 of the first comparator U1, the first comparator U1 inverts to output a low level, the first capacitor C1 discharges to the ground through the third resistor R3 and the first diode D1, so the voltage of the negative input terminal B1 of the first comparator U1 continuously decreases, and therefore the voltage of the negative input terminal B2 of the second comparator U2 also continuously decreases, as shown in fig. 5, when the voltage of the negative input terminal B2 of the second comparator U2 is lower than the voltage V2 of the positive input terminal B2 of the second comparator U2, the second comparator U2 inverts to output a high level, as shown in fig. 5, at time T2-T3 along line C2. The second comparator U2 outputs a high level, and the high level is amplified by the signal amplifying circuit 60 to drive the power switching transistor 30 to be turned on, the resonance circuit 10 operates, and the power supply circuit 20 discharges to the ground through the heating coil L1 and the power switching transistor Q1. Thus, the resonant circuit 10 continues to operate.
In the continuous operation process of the resonant circuit 10, if the resonant switch K1 is controlled to be turned off, the base electrode of the first triode Q1 is at a low level, according to the characteristics of the PNP type triode, the first triode Q1 is turned on, the electrolytic capacitor EC discharges to the ground through the fourth diode D4 and the emitter electrode and the collector electrode of the first triode Q1, after the voltage of the electrolytic capacitor EC is reduced to zero, the voltage at the positive input terminal A2 of the second comparator U2 is zero and is lower than the voltage at the negative input terminal B1 of the first comparator U1, the second comparator U2 outputs a low level, the power switch Q1 is turned off, and the resonant circuit 10 stops operating.
When the resistance of the eighth resistor R8 is fixed, the reference signal and the resistance of the seventh resistor R7 are in negative correlation, and the on time of the power switch 30 and the output power of the resonance circuit 10 are also in negative correlation with the resistance of the seventh resistor R7.
That is, the seventh resistor R7 may be an adjustable resistor, if the resistance of the seventh resistor R7 is reduced, the voltage division of the eighth resistor R8 to the preset power VCC increases, the charging voltage of the preset power VCC to the electrolytic capacitor EC increases, and as shown by the line a3 in fig. 6, the voltage at the positive input terminal B2 of the second comparator U2 may be stabilized at the voltage V3, wherein the voltage V3 is greater than the voltage V2 in fig. 5. Since the voltage V3 is greater than the voltage V2 in fig. 5, the times of the lines c3 0-t1.2 and t2.2-t3.2 in fig. 6 are greater than the times of the lines c3 0-t1 and t2-t3 in fig. 5, that is, the resistance of the seventh resistor R7 is reduced, the on time of the power switch Q1 is increased, the output power of the resonant circuit 10 is increased, and conversely, the resistance of the seventh resistor R7 is increased, the on time of the power switch Q1 is reduced, and the output power of the resonant circuit 10 is reduced.
Alternatively, when the resistance of the seventh resistor R7 is fixed, the reference signal and the resistance of the eighth resistor R8 are in positive correlation, and the on time of the power switch 30 and the output power of the resonance circuit 10 are both in positive correlation with the resistance of the eighth resistor R8.
Similarly, the eighth resistor R8 may be set as an adjustable resistor, if the resistance of the eighth resistor R8 is reduced, on a circuit in which the eighth resistor R8, the seventh resistor R7 and the third diode D3 are connected in series, the voltage division of the eighth resistor R8 to the preset power VCC is reduced, the charging voltage of the preset power VCC to the electrolytic capacitor EC is reduced, the on time of the power switching tube Q1 is reduced, the output power of the resonant circuit 10 is reduced, otherwise, the resistance of the eighth resistor R8 is increased, the on time of the power switching tube Q1 is increased, and the output power of the resonant circuit 10 is increased.
According to one embodiment of the present invention, as shown in fig. 2, the synchronization feedback circuit 70 includes: a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, and a third comparator U3.
One end of the tenth resistor R10 is connected with the input end of the resonant circuit 10; one end of the eleventh resistor R11 is connected with the other end of the tenth resistor R10, the other end of the eleventh resistor R11 is grounded, and a fourth node is arranged between the tenth resistor R10 and the eleventh resistor R11; one end of the twelfth resistor R12 is connected with one end of the power switch tube 30; one end of the thirteenth resistor R13 is connected with the other end of the twelfth resistor R12, the other end of the thirteenth resistor R13 is grounded, and a fifth node is arranged between the twelfth resistor R12 and the thirteenth resistor R13; the positive input end of the third comparator U3 is connected with the fourth node, the negative input end of the third comparator U3 is connected with the fifth node, and the output end of the third comparator U3 is connected with the output end of the first comparator U1.
That is, one end of the tenth resistor R10 is connected to the dc bus end of the power supply circuit 20, and the other end of the tenth resistor R10 is connected to the positive input end of the third comparator U3 to constitute sampling of the dc bus voltage. One end of the twelfth resistor R12 is connected to the collector of the power switching tube 30, and the other end of the twelfth resistor R12 is connected to the negative input end of the third comparator U3 to form a collector high voltage sampling of the power switching tube 30.
In one resonance period, the voltage across the resonance circuit 10 is fed back to the output terminal of the first comparator U1 in the signal generating circuit 40 through the synchronous feedback circuit 70 composed of the third comparator U3 to form a closed-loop negative feedback. By negative feedback, the output power of the resonant circuit 10 can be adjusted to be lower by adjusting the oscillation starting signal and further adjusting the driving signal when the output power of the resonant circuit 10 is higher than the preset power, and the output power of the resonant circuit 10 can be adjusted to be higher by adjusting the oscillation starting signal and the driving signal when the output power of the resonant circuit 10 is lower than the preset power. This stabilizes the output power of the resonant circuit 10 at a predetermined power.
According to one embodiment of the present invention, as shown in fig. 2, the signal amplifying circuit 60 includes a push-pull circuit composed of a second transistor Q2 and a third transistor Q3. The specific circuit structure of the push-pull circuit is shown in fig. 2, and will not be described here again.
According to one embodiment of the present invention, as shown in fig. 2, the power switch tube 30 may be an IGBT tube (Insulated Gate Bipolar Transistor ), and the resonant circuit 10 may include a heating coil L1 and a resonant capacitor C1 connected in parallel, wherein a collector of the IGBT tube is connected to the heating coil L1 and the resonant capacitor C1 connected in parallel, an emitter of the IGBT tube is grounded, and a gate of the IGBT tube is connected to the signal amplifying circuit 60.
In summary, according to the heating control device of the electromagnetic heating system according to the embodiment of the invention, the signal generating circuit generates the self-oscillating oscillation starting signal to control the resonant circuit to automatically resonate, the signal modulating circuit outputs the driving signal according to the oscillation starting signal and the reference signal to adjust the output power of the resonant circuit, and the synchronous feedback circuit is used for adjusting the oscillation starting signal according to the resonant state of the resonant circuit to form closed-loop negative feedback. Therefore, the device can build a resonant circuit through the minimum control feedback loop, has a simple circuit structure and a simple control process, and is stable and reliable.
Finally, the embodiment of the invention also provides an electromagnetic heating system, which comprises the heating control device of the electromagnetic heating system.
According to the electromagnetic heating system provided by the embodiment of the invention, the resonant circuit can be built through the minimum control feedback loop, the circuit structure is simple, and the control process is simple.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (10)
1. A heating control device of an electromagnetic heating system, comprising:
a resonant circuit; the resonant circuit comprises a heating coil and a resonant capacitor;
the power supply circuit is connected with the input end of the resonant circuit to supply power for the resonant circuit;
the collector of the power switch tube is connected with the output end of the resonant circuit, and the emitter of the power switch tube is grounded;
a signal generation circuit for generating a self-oscillating start signal;
the signal modulation circuit is connected with the signal generation circuit and is used for outputting a driving signal according to the vibration starting signal and the reference signal;
the signal amplification circuit is respectively connected with the signal modulation circuit and the control electrode of the power switch tube and is used for amplifying the driving signal so as to drive the power switch tube to be turned on or turned off through the amplified driving signal; and
and the synchronous feedback circuit is respectively connected with the resonant circuit and the signal generation circuit and is used for adjusting the oscillation starting signal according to the resonance state of the resonant circuit.
2. The heating control device of an electromagnetic heating system according to claim 1, wherein the signal generating circuit includes:
the power supply end of the first comparator is connected with a preset power supply, and the ground of the first comparator is grounded;
one end of the first resistor is connected with a preset power supply;
one end of the second resistor is connected with the other end of the first resistor, the other end of the second resistor is connected with the output end of the first comparator, a sixth node is arranged between the second resistor and the first resistor, and the sixth node is connected with the positive input end of the first comparator;
one end of the first capacitor is connected with the negative input end of the first comparator, the other end of the first capacitor is grounded, and the negative input end of the first comparator is used as the output end of the signal generating circuit and is connected with the signal modulating circuit;
one end of the third resistor is respectively connected with one end of the first capacitor and the negative input end of the first comparator;
one end of the fourth resistor is connected with the other end of the third resistor, and the other end of the fourth resistor is connected with the preset power supply;
the anode of the first diode is connected with the other end of the third resistor and one end of the fourth resistor respectively, and the cathode of the first diode is connected with the output end of the first comparator.
3. The heating control device of an electromagnetic heating system according to claim 2, wherein,
when the first comparator outputs a high-level signal, the first capacitor, the third resistor and the fourth resistor form a charging loop;
when the first comparator outputs a low level, the first capacitor, the third resistor and the first diode form a discharge loop.
4. The heating control device of an electromagnetic heating system according to claim 1, wherein the signal modulation circuit includes:
one end of the resonant switch is connected with a preset power supply;
one end of the fifth resistor is connected with the other end of the resonant switch;
one end of the sixth resistor is connected with the other end of the fifth resistor, and the other end of the sixth resistor is grounded, wherein a first node is arranged between the fifth resistor and the sixth resistor;
the anode of the third diode is connected with one end of the fifth resistor and the other end of the resonant switch;
a seventh resistor, one end of which is connected with the cathode of the third diode;
one end of the eighth resistor is connected with the other end of the seventh resistor, and the other end of the eighth resistor is grounded, wherein a second node is arranged between the eighth resistor and the seventh resistor;
the emitter of the first triode is connected with the second node, the collector of the first triode is grounded, and the base of the first triode is connected with the first node;
a ninth resistor, one end of which is connected with the second node;
a fourth diode connected in parallel with the ninth resistor;
the positive electrode of the electrolytic capacitor is connected with the other end of the ninth resistor, and the negative electrode of the electrolytic capacitor is grounded, wherein a third node is arranged between the electrolytic capacitor and the ninth resistor and is used for providing the reference signal;
the positive input end of the second comparator is connected with the third node, the negative input end of the second comparator is used as the input end of the signal modulation circuit to be connected with the output end of the signal generation circuit, the output end of the second comparator is used as the output end of the signal modulation circuit to be connected with the signal amplification circuit, the power end of the second comparator is connected with a preset power supply, and the ground of the second comparator is grounded.
5. The heating control device of an electromagnetic heating system according to claim 4, wherein,
when the resonant switch is disconnected, the resonant circuit is in a stop working state;
when the resonant switch is closed, the resonant circuit is in a working state.
6. The heating control device of claim 4, wherein when the resistance of the eighth resistor is fixed, the reference signal and the resistance of the seventh resistor are in negative correlation, and the on time of the power switch tube and the output power of the resonant circuit are also in negative correlation with the resistance of the seventh resistor.
7. The heating control device of claim 4, wherein when the resistance of the seventh resistor is fixed, the reference signal and the resistance of the eighth resistor are in positive correlation, and the on time of the power switch tube and the output power of the resonant circuit are both in positive correlation with the resistance of the eighth resistor.
8. The heating control device of an electromagnetic heating system according to claim 2, wherein the synchronous feedback circuit includes:
a tenth resistor, one end of which is connected with the input end of the resonant circuit;
an eleventh resistor, wherein one end of the eleventh resistor is connected with the other end of the tenth resistor, the other end of the eleventh resistor is grounded, and a fourth node is arranged between the tenth resistor and the eleventh resistor;
a twelfth resistor, wherein one end of the twelfth resistor is connected with one end of the power switch tube;
a thirteenth resistor, one end of which is connected with the other end of the twelfth resistor, the other end of which is grounded, and a fifth node is arranged between the twelfth resistor and the thirteenth resistor;
and the positive input end of the third comparator is connected with the fourth node, the negative input end of the third comparator is connected with the fifth node, and the output end of the third comparator is connected with the output end of the first comparator.
9. The heating control device of an electromagnetic heating system according to any one of claims 1 to 8, wherein the signal amplifying circuit includes a push-pull circuit constituted by a second transistor and a third transistor.
10. An electromagnetic heating system, characterized by comprising a heating control device of an electromagnetic heating system according to any one of claims 1-9.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510895322.1A CN106851881B (en) | 2015-12-07 | 2015-12-07 | Electromagnetic heating system and heating control device thereof |
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| CN201510895322.1A CN106851881B (en) | 2015-12-07 | 2015-12-07 | Electromagnetic heating system and heating control device thereof |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203136220U (en) * | 2013-02-21 | 2013-08-14 | 美的集团股份有限公司 | Electromagnetic heating device |
| CN104010399A (en) * | 2013-02-21 | 2014-08-27 | 美的集团股份有限公司 | Electromagnetic heating apparatus and control method thereof |
| CN204442725U (en) * | 2015-03-04 | 2015-07-01 | 佛山市顺德区美的电热电器制造有限公司 | The zero passage of electromagnetic heating system and breaker in middle pipe thereof opens checkout gear |
| CN205232487U (en) * | 2015-12-07 | 2016-05-11 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating system and heating control device thereof |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203136220U (en) * | 2013-02-21 | 2013-08-14 | 美的集团股份有限公司 | Electromagnetic heating device |
| CN104010399A (en) * | 2013-02-21 | 2014-08-27 | 美的集团股份有限公司 | Electromagnetic heating apparatus and control method thereof |
| CN204442725U (en) * | 2015-03-04 | 2015-07-01 | 佛山市顺德区美的电热电器制造有限公司 | The zero passage of electromagnetic heating system and breaker in middle pipe thereof opens checkout gear |
| CN205232487U (en) * | 2015-12-07 | 2016-05-11 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating system and heating control device thereof |
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