CN107027201A - Electromagnetic heater and its method for noise reduction control - Google Patents
Electromagnetic heater and its method for noise reduction control Download PDFInfo
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- CN107027201A CN107027201A CN201610072354.6A CN201610072354A CN107027201A CN 107027201 A CN107027201 A CN 107027201A CN 201610072354 A CN201610072354 A CN 201610072354A CN 107027201 A CN107027201 A CN 107027201A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/02—Induction heating
- H05B6/06—Control, e.g. of temperature, of power
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Abstract
The invention discloses a kind of electromagnetic heater and its method for noise reduction control, it the described method comprises the following steps：The operating current of the electromagnetic heater is sampled to obtain current sampling signal；When controlling PPG output control signals to control that power switch pipe is opened in the electromagnetic heater, the current sampling signal is compared with default sine wave signal；When the magnitude of voltage of the current sampling signal is more than the phase instantaneous voltage in the same time corresponding to the default sine wave signal, the PPG shut-offs output is controlled to adjust each service time of the power switch pipe, so that the waveform envelope of the operating current is consistent with the current waveform envelope corresponding to the default sine wave signal, so as to change the frequency characteristic of the operating current of electromagnetic heater, and then change the frequency characteristic for the noise for being delivered to pan, so that the heating lower noise of pan, lifts the experience of user.
Description
Technical field
The present invention relates to electromagnetic heating technique field, the method for noise reduction control and one kind of more particularly to a kind of electromagnetic heater
Electromagnetic heater.
Background technology
Related electromagnetic heater such as electromagnetic oven uses mains-supplied, and civil power is becoming Rectified alternating current after over commutation,
Wherein, Rectified alternating current includes the frequency content of fundamental frequency 100Hz and each rank frequency multiplication, and the Rectified alternating current is further converted into containing
There is the electric current of identical frequency content, and be eventually transferred to by drum magnetic coupling on pan noise, user is felt noisy,
Experience effect is decreased obviously.But, correlation technique can not eliminate the harmonious wave component of the direct current fundamental wave after rectification, and then can not drop
Low pan noise.
Therefore, correlation technique needs to be improved.
The content of the invention
It is contemplated that at least solving one of technical problem in above-mentioned technology to a certain extent.Therefore, one of the present invention
Purpose is to propose a kind of method for noise reduction control of electromagnetic heater, and this method can be by changing the work of electromagnetic heater
The waveform of electric current reduces the purpose that pan heats noise to reach.
It is another object of the present invention to propose a kind of electromagnetic heater.
To reach above-mentioned purpose, a kind of method for noise reduction control for electromagnetic heater that one aspect of the present invention embodiment is proposed, bag
Include following steps：The operating current of the electromagnetic heater is sampled to obtain current sampling signal；In control PPG
Output control signal with when controlling that power switch pipe is opened in the electromagnetic heater, to the current sampling signal with it is default
Sine wave signal be compared；When the magnitude of voltage of the current sampling signal is more than corresponding to the default sine wave signal
Phase in the same time instantaneous voltage when, control PPG shut-off output to adjust each service time of the power switch pipe,
So that the waveform envelope of the operating current is consistent with the current waveform envelope corresponding to the default sine wave signal.
The method for noise reduction control of electromagnetic heater according to embodiments of the present invention, is carried out to the operating current of electromagnetic heater
Sampling is controlling PPG output control signals to be adopted when controlling power switch pipe to open to electric current to obtain current sampling signal
Sample signal is compared with default sine wave signal, when the magnitude of voltage of current sampling signal is more than default sine wave signal institute
Corresponding phase in the same time instantaneous voltage when, control PPG shut-off outputs to adjust each service time of power switch pipe, with
The waveform envelope and the current waveform envelope corresponding to default sine wave signal for making operating current are consistent, so as to change electricity
The frequency characteristic of the operating current of magnetic heater, and then change the frequency characteristic for the noise for being delivered to pan so that pan
Lower noise is heated, the experience of user is lifted.
According to one embodiment of present invention, the current sampling signal and default sine wave signal are carried out by comparator
Compare, wherein, when the comparator output switching activity signal, the PPG shut-offs output can be directly controlled, or delay is in advance
If controlling the PPG shut-offs output after the time.
According to one embodiment of present invention, the default sine wave signal is the sine wave of 2 times of electric main frequencies.
Further, the control signal that the PPG is exported within each cycle of the sine wave of 2 times of electric main frequencies
Pulse width first become and diminish again greatly.
Wherein, the crest value correspondence maximum pulse of the sine wave of 2 times of electric main frequencies, 2 times of exchanges city
The valley value correspondence minimum pulse width of the sine wave of electric frequency.
To reach above-mentioned purpose, a kind of electromagnetic heater that another aspect of the present invention embodiment is proposed, including：Electric current is adopted
Sample unit, the current sampling unit is used to sample to obtain current sample to the operating current of the electromagnetic heater
Signal；Resonance heating unit；Rectification filtering unit, the rectification filtering unit is used to carry out at rectifying and wave-filtering electric main
The resonance heating unit is supplied after reason；Power switch pipe, the power switch pipe is used to control the resonance heating unit to enter
Row resonant operational；Driver element, the driver element is used to drive turning on and off for the power switch pipe；Comparing unit,
The comparing unit is used to be compared the current sampling signal with default sine wave signal；Main control unit, the master
Control unit is used to control PPG to output control signals to the driver element to be controlled the power switch pipe, and in institute
State current sampling signal magnitude of voltage be more than the default sine wave signal corresponding to phase in the same time instantaneous voltage when control
The PPG shut-offs output is to adjust each service time of the power switch pipe, so that the waveform envelope of the operating current
It is consistent with the current waveform envelope corresponding to the default sine wave signal.
Electromagnetic heater according to embodiments of the present invention, is entered by current sampling unit to the operating current of electromagnetic heater
Row sampling is to obtain current sampling signal, and main control unit is when controlling PPG output control signals to control power switch pipe to open
Current sampling signal is compared with default sine wave signal, when the magnitude of voltage of current sampling signal is more than default sine
Phase corresponding to ripple signal in the same time instantaneous voltage when, control PPG shut-offs output is to adjust each open-minded of power switch pipe
Time, so that the waveform envelope of operating current is consistent with the current waveform envelope corresponding to default sine wave signal, from
And change the frequency characteristic of the operating current of electromagnetic heater, and then change the frequency characteristic for the noise for being delivered to pan, make
The heating lower noise of pan is obtained, the experience of user is lifted.
According to one embodiment of present invention, the comparing unit includes comparator, wherein, when the comparator output switching activity
During signal, the main control unit can directly control the PPG shut-offs output, or control the PPG after delay preset time
Shut-off output.
According to one embodiment of present invention, the default sine wave signal is the sine wave of 2 times of electric main frequencies.
Further, the control signal that the PPG is exported within each cycle of the sine wave of 2 times of electric main frequencies
Pulse width first become and diminish again greatly.
Wherein, the crest value correspondence maximum pulse of the sine wave of 2 times of electric main frequencies, 2 times of exchanges city
The valley value correspondence minimum pulse width of the sine wave of electric frequency.
Brief description of the drawings
Fig. 1 is the flow chart of the method for noise reduction control of the electromagnetic heater according to the embodiment of the present invention；
Fig. 2 is the flow chart of the method for noise reduction control of the electromagnetic heater according to one embodiment of the invention；
Fig. 3 is the block diagram of the electromagnetic heater according to the embodiment of the present invention；
Fig. 4 is the electromagnetic heater electric main and rectified voltage and default sine wave according to one embodiment of the invention
The corresponding schematic diagram of the waveform and frequency spectrum of signal；
Fig. 5 is the electromagnetic heater electric main and operating current envelope and PPG waveform according to one embodiment of the invention
Corresponding schematic diagram；And
Fig. 6 is the circuit theory diagrams of the electromagnetic heater according to one embodiment of the invention.
Reference：
Current sampling unit 10, rectification filtering unit 20, resonance heating unit 30, power switch pipe Q1, driver element 40,
Comparing unit 60 and main control unit 50；
Rectifier bridge stack 201 and filter inductance L1 and filter capacitor C1；
Resonant inductance L2 and resonant capacitance C2；
Switching power supply 70, synchronized sampling unit 80 and man-machine interaction unit 90；
Comparator U1, signal provide unit 11, signal source circuit 101, gain control circuit 102, sampling resistor R1 and
Current-limiting resistance R2.
Embodiment
Embodiments of the invention are described below in detail, the example of the embodiment is shown in the drawings, wherein identical from beginning to end
Or similar label represents same or similar element or the element with same or like function.Retouched below with reference to accompanying drawing
The embodiment stated is exemplary, it is intended to for explaining the present invention, and be not considered as limiting the invention.
The noise of electromagnetic heater in correlation technique is simply introduced first.
In the related art, electromagnetic heater uses mains-supplied, civil power in electromagnetic heater by EMC circuits and
Subsequent conditioning circuit is supplied to after bridge rectifier.Inventor has found：Civil power can be by original 50Hz by bridge rectifier
Single-frequency alternating current becomes to include the Rectified alternating current of hundreds of hz AC compositions, wherein, Rectified alternating current mainly includes
100~500Hz low-order harmonic, after Rectified alternating current is supplied to the subsequent conditioning circuit of electromagnetic heater, electromagnetic heater
Operating current also there is the low-order harmonic of identical frequency simultaneously, and be eventually transferred on pan noise so that pan noise has
There is the low-order harmonic of identical frequency.The above-mentioned low-order harmonic noise for being distributed in 100~500Hz can make user feel noisy, so
Noise is produced in pan heating process, Consumer's Experience effect is decreased obviously.
Based on this, the method for noise reduction control and one kind that the embodiment of the present invention proposes a kind of electromagnetic heater realize this method
Electromagnetic heater.
The method for noise reduction control and electricity of the electromagnetic heater that propose according to embodiments of the present invention described with reference to the accompanying drawings
Magnetic heater.
Wherein, electromagnetic heater such as electromagnetic oven is used to carry out resonance heating to pan.As shown in figure 3, Electromagnetic Heating is filled
Putting may include current sampling unit 10, rectification filtering unit 20, resonance heating unit 30, power switch pipe (such as IGBT)
Q1, driver element 40, comparing unit 60 and main control unit 50.Wherein, the alternating current that AC power is provided passes through EMC
Pulsating direct current is transformed to after (Electro Magnetic Compatibility, Electro Magnetic Compatibility) circuit, rectification filtering unit 20
Electricity；Rectified alternating current is supplied resonance heating unit 30 by rectification filtering unit 20；Main control unit 50 is used to control driver element
40 by the driving power switching tube Q1 of driver element 40 to be turned on and off；Resonance heating unit 30 is in power switch pipe Q1
Resonance is produced during turning on and off, and produces periodically variable magnetic field, magnetic fields produce the bottom of a pan in pan bottom
Raw vortex, and heat is produced simultaneously.Hereby it is achieved that the heating to pan.
Fig. 1 is the flow chart of the method for noise reduction control of the electromagnetic heater according to the embodiment of the present invention.As shown in figure 1, should
The method for noise reduction control of electromagnetic heater comprises the following steps：
S1：The operating current of electromagnetic heater is sampled to obtain current sampling signal.
That is, during electromagnetic heater heating, can be by current sampling unit come electromagnetic heater of sampling
Operating current is to obtain current sampling signal.Wherein, current sampling signal can be that current peak or electric current are average
Value, is specifically determined by the frequency characteristic of current sampling unit.
It should be noted that requiring different according to current sample, sample mode, sampling location can be different, such as sampling
Position, can individual power switch pipe emitter stage gather electric current, can also the rectification circuit in rectification filtering unit 20 with
Electric current is gathered between filter circuit；For example for sample mode, can be, but not limited to resistance sampling, current transformer sampling or
Hall element is sampled.
S2：Control PPG (Programmable Pulse Generator, programmable pulse generator) output control signals with
When power switch pipe is opened in control electromagnetic heater, current sampling signal is compared with default sine wave signal.
According to one embodiment of present invention, as shown in Figures 4 and 5, default sine wave signal can be 2 times of electric main frequencies
The sine wave of rate, also, zero passage detection is carried out to obtain zero crossing to electric main, default sine wave signal is with exchanging city
Electricity can have following phase relation：The zero crossing of the trough correspondence electric main of default sine wave signal.More specifically, default
Sine wave signal can be the positively biased sine wave signal of 1/2 amplitude, also, default sine wave signal frequency be 2 times
Mains frequency such as 100Hz, phase is identical with the phase of electric main；The amplitude of default sine wave signal can be according to heating
Power requirement is adjusted, it is necessary to explanation, current signal type difference, corresponding default sine wave during identical heating power
The amplitude of signal is also different.
Specifically, within each cycle of the sine wave of 2 times of electric main frequencies PPG export control signal pulse width
First become and diminish again greatly.In other words, the pulse width for the control signal that PPG is exported first becomes in every half wave cycles of electric main
Diminish again greatly, that is, say that value of the pulse width for the control signal that PPG is exported in every half wave cycles of electric main is not constant
Value.It should be noted that pulse width refers to the power switch pipe such as IGBT under the control of the PPG control signals exported
The time span opened.
More specifically, the crest value correspondence maximum pulse of the sine wave of 2 times of electric main frequencies, 2 times of electric main frequencies
Sine wave valley value correspondence minimum pulse width.
In the example of the present invention, the signal source of default sine wave signal can be independent synchronous with electric main
Signal or the fundamental frequency signal taken out from the Rectified alternating current after rectification or by main control unit D/A turn
Change the getable analog sine wave signal of work(.It should be appreciated that due to non-linear, the default sine wave letter of actual circuit
Number still allow containing certain harmonic components, circuit is different, and the harmonic content of default sine wave signal has larger difference, this
Inventive embodiments are not specially limited.
In addition, the amplitude of default sine wave signal is determined by signal source output amplitude and gain control circuit, and gain is controlled
The gain of circuit by main control unit according to heating power requirement determine, or default sine wave signal amplitude by main control unit
D/A translation functions directly determine.
S3：When the magnitude of voltage of current sampling signal is more than the phase instantaneous voltage in the same time corresponding to default sine wave signal,
Control PPG shut-off outputs to adjust each service time of power switch pipe so that the waveform envelope of operating current with it is default
Current waveform envelope corresponding to sine wave signal is consistent.
It should be noted that with reference to the change curve schematic diagram of operating current in Fig. 5, solid line is represented in harmonic period in Fig. 5
The current waveform of forward stream overcurrent sampling unit be in the actual waveform of operating current, Fig. 5 dotted line represent current peak with
The curve of time change is the waveform envelope of operating current.
That is, current sampling signal and default sine wave signal are contrasted to generate comparative result, and according to than
The time span of the control signal of PPG outputs each compared with structure determination.
In the related art, in the case where PPG pulse widths are fixed, the ON time of power switch pipe is fixed, by exchanging
The voltage frequency characteristics for the Rectified alternating current that electricity change swaps out can be delivered to the frequency characteristic of the operating current of electromagnetic heater,
For example Rectified alternating current include 100Hz, 200Hz, 300Hz ... harmonic wave, it will so that the frequency characteristic of operating current
Including 100Hz, 200Hz, 300Hz ... harmonic wave, be eventually transferred on pan noise, make pan noise that there is same frequency
The low-order harmonic of rate.
In an embodiment of the present invention, as shown in Figures 4 and 5, it is right during control electromagnetic heater is heated
The operating current of electromagnetic heater is sampled to obtain current sampling signal, and electric current is adopted when power switch pipe is opened
Sample signal is compared with default sine wave signal, then when the magnitude of voltage of current sampling signal reaches default sine wave letter
Phase corresponding to number in the same time instantaneous voltage when, control PPG shut-off outputs are to control power switch pipe to turn off, so as to adjust
Each service time of power switch pipe in electromagnetic heater, carry out the frequency characteristic of the operating current of electromagnetic heater
Change, for example, make the waveform envelope of operating current close to the sine wave of 2 times of electric main frequencies, so as to avoid each harmonic energy
Amount is delivered on pan noise, so as to reduce pan heating noise.
Specifically, as shown in Fig. 2 the method for noise reduction control of the embodiment of the present invention specifically includes following steps：
S101：PPG output control signals are controlled after synchronizing signal is obtained, to control power switch pipe open-minded.
S102：Sample electromagnetic heater operating current to obtain current sampling signal.
S103：Judge whether the magnitude of voltage of current sampling signal is more than the phase voltage in the same time corresponding to default sine wave signal
Instantaneous value Vref.
If it is, performing step S104：If it is not, then continuing executing with step S103.
S104：PPG shut-off outputs are controlled to control power switch pipe to turn off, return to step S101.
According to the specific embodiment of the present invention, current sampling signal and default sine wave signal are carried out by comparator
Compare, wherein, when comparator output switching activity signal, PPG shut-off outputs can be directly controlled, or after delay preset time
Control the PPG shut-offs output.
Specifically, current sampling signal can be input to the first input end of comparator, and default sine wave signal is carried
The second input of comparator is supplied to, when the magnitude of voltage Vi of current sampling signal reaches the voltage transient of default sine wave signal
During value Vref, the output signal Isense of comparator is overturn, and now can determine whether that operating current reaches shut-off controlling value, and
Control PPG shut-off outputs.
After the output signal Isense of comparator is overturn, PPG shut-off outputs can be controlled immediately, can also be postponed pre-
If controlling PPG shut-off outputs after the time again, turn off, can be controlled by software mode again after so postponing preset time,
So as to lift applicability, and simplify the design of the gain control circuit of default sine wave signal.
According to the specific example of the present invention, power switch pipe can be IGBT, and the operating current of electromagnetic heater can be
IGBT emitter current.So, after control PPG output control signals, IGBT emitter current gradually increases,
The magnitude of voltage of current sampling signal accordingly increases and is input to the first input end of comparator, when the magnitude of voltage of current sampling signal
More than the phase corresponding to default sine wave signal in the same time instantaneous voltage Vref when, comparator is overturn, and can now be led to
Cross hardware circuit and directly control PPG shut-off outputs, or output is turned off by program indirect control PPG.Above procedure is realized once
Current control.
After each current control in the 1/2 electric main cycle that completed, 1 complete waveform control is completed, operating current
Waveform envelope is suitable with the current waveform envelope corresponding to default sine wave signal, thus, when default sine wave signal is
During the sine wave of 2 times of electric main frequencies with smaller harmonic content, the noise being delivered on pan also only has 2 times of exchange cities
Other harmonic components of electric frequency and very little, it is humorous compared with the noise that the fixation PPG way of outputs in correlation technique are produced
Ripple amount is decreased obviously, and noise also accordingly declines, and described herein is that default sine wave signal can be obtained by experimental data
One group it is corresponding be most suitable under actual service conditions current waveform data formation envelope.
To sum up, the method for noise reduction control of electromagnetic heater according to embodiments of the present invention, to the work electricity of electromagnetic heater
Stream is sampled to obtain current sampling signal, and when controlling PPG output control signals to control power switch pipe to open pair
Current sampling signal is compared with default sine wave signal, when the magnitude of voltage of current sampling signal is more than default sine wave
Phase corresponding to signal in the same time instantaneous voltage when, control PPG shut-offs output is to adjust when opening every time of power switch pipe
Between, so that the waveform envelope of operating current is consistent with the current waveform envelope corresponding to default sine wave signal, so that
Change the frequency characteristic of the operating current of electromagnetic heater, and then change the frequency characteristic for the noise for being delivered to pan so that
The heating lower noise of pan, lifts the experience of user.
The embodiment of the present invention also proposed a kind of electromagnetic heater of the use above method.
Fig. 3 is the block diagram of electromagnetic heater according to embodiments of the present invention.As shown in figure 3, electromagnetic heater
Including：Current sampling unit 10, rectification filtering unit 20, resonance heating unit 30, power switch pipe Q1, driver element
40th, comparing unit 60 and main control unit 50.
Wherein, current sampling unit 10 is used to sample to obtain current sampling signal to the operating current of electromagnetic heater.
Wherein, current sampling signal can be current peak or current average, specifically by the frequency of current sampling unit
Characteristic is determined.It should be noted that require different according to current sample, the sample mode of current sampling unit 10, sampling location
Can be different, such as sampling location, current sampling unit 10 can gather electric current in the emitter stage of individual power switch pipe,
Electric current can also be gathered between the rectification circuit in rectification filtering unit 20 and filter circuit；For example for sample mode, electricity
Stream sampling unit 10 can be but be not limited to resistance sampling, current transformer sampling or Hall element sampling.
Rectification filtering unit 20 is used to carry out rectifying and wave-filtering treatment and supplied resonance heating unit 30 to electric main；Power switch
Pipe Q1 is used to control resonance heating unit 30 to carry out resonant operational；Driver element 40 is used for opening for driving power switching tube Q1
Logical and shut-off.In one embodiment of the present of invention, as shown in figure 3, power switch pipe Q1 can be IGBT, rectifying and wave-filtering
Unit 20 includes rectifier bridge stack 201 and filter inductance L1 and filter capacitor C1, and resonance heating unit 30 includes in parallel connect
The resonant inductance L2 and resonant capacitance C2 connect.
Comparing unit 60 is used to be compared current sampling signal with default sine wave signal；Main control unit 50 is used to control
PPG processed outputs control signals to driver element 40 to be controlled to power switch pipe Q1, and in the electricity of current sampling signal
Pressure value be more than phase corresponding to default sine wave signal in the same time instantaneous voltage when control PPG shut-off outputs to adjust power
Switching tube Q1 each service time, so that the waveform envelope of operating current and the electric current corresponding to default sine wave signal
Waveform envelope is consistent.That is, comparing unit 60 is contrasted current sampling signal with default sine wave signal
To generate comparative result, and main control unit 50 determines that the time for the control signal that each PPG is exported is long according to comparative structure
Degree.
It should be noted that with reference to the change curve schematic diagram of operating current in Fig. 5, solid line is represented in harmonic period in Fig. 5
The current waveform of forward stream overcurrent sampling unit be in the actual waveform of operating current, Fig. 5 dotted line represent current peak with
The curve of time change is the waveform envelope of operating current.
As shown in figure 3, above-mentioned electromagnetic heater also includes switching power supply 70, synchronized sampling unit 80 and man-machine friendship
Mutual unit 90 etc., wherein, switching power supply 70 is used for the direct current that AC power is converted to first voltage such as 5V
Source and second voltage such as 18V dc source, wherein, the direct-current power supply main control unit 50 of first voltage, the second electricity
The direct-current power supply driver element 40 of pressure, first voltage is less than second voltage；Synchronized sampling unit 80 is used to detect resonance
The voltage at inductance L2 two ends, and the voltage at resonant inductance L2 two ends is compared to generate synchronizing signal, main control unit 50
Control PPG outputs control signals to power switch pipe Q1 after synchronizing signal is obtained；Man-machine interaction unit 90 is used to receive
Instruction and shown to user that user inputs.
Specifically, main control unit 50 controls PPG output control signals to control power switch after synchronizing signal is obtained
Pipe Q1 is open-minded, and during power switch pipe Q1 is opened, the work for electromagnetic heater of being sampled by current sampling unit 10
Make electric current to obtain current sampling signal, then main control unit 50 judges the magnitude of voltage I of current sampling signal whether more than default
Sine wave signal corresponding to phase instantaneous voltage Vref in the same time, if I is more than Vref, control PPG shut-off outputs
To control power switch pipe Q1 to turn off, and detect synchronizing signal：If I is less than or equal to Vref, whether continuation judges I
More than Vref.
In the related art, in the case where PPG pulse widths are fixed, power switch pipe Q1 ON time is fixed, by
The frequency that the voltage frequency characteristics for the Rectified alternating current that convert alternating current goes out can be delivered to the operating current of electromagnetic heater is special
Property, such as Rectified alternating current include 100Hz, 200Hz, 300Hz ... harmonic wave, it will so that the frequency of operating current is special
Property also include 100Hz, 200Hz, 300Hz ... harmonic wave, be eventually transferred on pan noise, make pan noise that there is phase
The low-order harmonic of same frequency.
In an embodiment of the present invention, as shown in Figures 4 and 5, during control electromagnetic heater is heated, lead to
Overcurrent sampling unit 10 is sampled to obtain current sampling signal to the operating current of electromagnetic heater, and main control unit
50 are compared when power switch pipe Q1 is opened to current sampling signal with default sine wave signal, and work as current sample
The magnitude of voltage of signal reach phase corresponding to default sine wave signal in the same time instantaneous voltage when, control PPG shut-off outputs
To control power switch pipe to turn off, so as to adjust each service time of power switch pipe in electromagnetic heater, add electromagnetism
The frequency characteristic of the operating current of thermal is changed, for example, make the waveform envelope of operating current close to 2 times of electric mains frequencies
The sine wave of rate, so as to avoid each harmonic energy from being delivered on pan noise, so as to reduce pan heating noise.
According to one embodiment of present invention, as shown in Figures 4 and 5, default sine wave signal can be 2 times of electric main frequencies
The sine wave of rate, also, zero passage detection is carried out to obtain zero crossing to electric main, default sine wave signal is with exchanging city
Electricity can have following phase relation：The zero crossing of the trough correspondence electric main of default sine wave signal.More specifically, default
Sine wave signal can be the positively biased sine wave signal of 1/2 amplitude, also, default sine wave signal frequency be 2 times
Mains frequency such as 100Hz, phase is identical with the phase of electric main；The amplitude of default sine wave signal can be according to heating
Power requirement is adjusted, it is necessary to explanation, current signal type difference, corresponding default sine wave during identical heating power
The amplitude of signal is also different.
Specifically, within each cycle of the sine wave of 2 times of electric main frequencies PPG export control signal pulse width
First become and diminish again greatly.In other words, the pulse width for the control signal that PPG is exported first becomes in every half wave cycles of electric main
Diminish again greatly, that is, say that value of the pulse width for the control signal that PPG is exported in every half wave cycles of electric main is not constant
Value.It should be noted that pulse width refers to the power switch pipe such as IGBT under the control of the PPG control signals exported
The time span opened.
More specifically, the crest value correspondence maximum pulse of the sine wave of 2 times of electric main frequencies, 2 times of electric main frequencies
Sine wave valley value correspondence minimum pulse width.
In the example of the present invention, the signal source of default sine wave signal can be independent synchronous with electric main
Signal or the fundamental frequency signal taken out from the Rectified alternating current after rectification or by main control unit D/A turn
Change the getable analog sine wave signal of work(.It should be appreciated that due to non-linear, the default sine wave letter of actual circuit
Number still allow containing certain harmonic components, circuit is different, and the harmonic content of default sine wave signal has larger difference, this
Inventive embodiments are not specially limited.
According to the specific embodiment of the present invention, as Figure 4-Figure 6, comparing unit 60 includes comparator U1, wherein,
When comparator U1 output switching activity signals, main control unit 50 can directly control PPG shut-off outputs, or delay preset time
Control PPG shut-offs output afterwards.
It should be noted that comparator U1 can be integrated in comparator or master control list inside main control unit 50
The comparator being independently arranged outside member 50.
Specifically, comparator U1 first input end can receive current sampling signal with current sampling unit 10, compare
Device U2 the second input can be connected with providing the signal offer unit 70 of default sine wave signal, and comparator U2's is defeated
Go out end with main control unit 50 to be connected.When the magnitude of voltage Vi of current sampling signal reaches the voltage transient of default sine wave signal
During value Vref, comparator U1 output signal Isense is overturn, and now main control unit 50 can determine whether that operating current reaches
Controlling value is turned off, and controls PPG shut-off outputs.
After the output signal Isense of comparator is overturn, main control unit 50 can control PPG shut-off outputs immediately,
Main control unit 50 can also postpone to control PPG shut-off outputs after preset time again, be turned off again after so postponing preset time,
It can be controlled by software mode, so as to lift applicability, and simplify the gain control electricity of default sine wave signal
The design on road.
According to the specific embodiment of the present invention, unit is provided there is provided the signal of default sine wave signal as shown in Figure 6
11 include：Signal source circuit 101 and gain control circuit 102.
Wherein, signal source circuit 101 is used for Rectified alternating current after the acquirement rectification of the output end of rectifier bridge stack 201, and to pulsation
The fundamental frequency signal that direct current is filtered to take out from the Rectified alternating current after rectification, so as to obtain the less sine of harmonic content
Ripple；Gain control circuit 102 is used to be adjusted to obtain default sine wave signal the amplitude of the fundamental frequency signal of taking-up
Signal.Specifically, the particular circuit configurations of signal source circuit 101 and gain control circuit 102, annexation such as Fig. 6 institutes
Show, repeat no more here.
It should be noted that the amplitude of default sine wave signal is by the output amplitude of signal source circuit 101 and gain control circuit
102 are determined, and the gain of gain control circuit 102 can be determined by main control unit 50 according to heating power requirement, or default
The amplitude of sine wave signal directly determined by the D/A translation functions of main control unit 50.
According to the specific embodiment of the present invention, as Figure 4-Figure 6, power switch pipe can be IGBT, current sampling circuit
10 include sampling resistor R1 and current-limiting resistance R2, wherein, sampling resistor R1 one end is connected with IGBT emitter stage,
Sampling resistor R1 other end ground connection；Current-limiting resistance R2 one end is connected with sampling resistor R1 one end, current-limiting resistance R2
The other end be connected with comparator U1 first input end.
With reference to Fig. 6 example, the control process of main control unit 50 is as follows：After control PPG output control signals, IGBT
Emitter current gradually increase, the partial pressure that sampling resistor R1 is obtained accordingly increases, and sampling resistor R1 partial pressure value passes through limit
Leakage resistance R2 is input to comparator U1 first input end, when sampling resistor R1 partial pressure value is believed more than default sine wave
Phase corresponding to number in the same time instantaneous voltage Vref when, comparator U1 output signal is overturn, and main control unit 50 connects
Receive after energizing signal, PPG shut-off outputs can be directly controlled by hardware circuit, or turned off by program indirect control PPG
Output.Above procedure realizes primary current control.
After each current control in the 1/2 electric main cycle that completed, 1 complete waveform control is completed, operating current
Waveform envelope is suitable with the current waveform envelope corresponding to default sine wave signal, thus, when default sine wave signal is
During the sine wave of 2 times of electric main frequencies with smaller harmonic content, the noise being delivered on pan also only has 2 times of exchange cities
Other harmonic components of electric frequency and very little, it is humorous compared with the noise that the fixation PPG way of outputs in correlation technique are produced
Ripple amount is decreased obviously, and noise also accordingly declines.
In some embodiments of the invention, electromagnetic heater can be electromagnetic oven, electromagnetic rice cooker or prevention electromagnetic pressure cooker.
To sum up, electromagnetic heater according to embodiments of the present invention, the work by current sampling unit to electromagnetic heater
Electric current is sampled to obtain current sampling signal, and main control unit is controlling PPG output control signals to control power switch pipe
Current sampling signal is compared with default sine wave signal when opening, preset when the magnitude of voltage of current sampling signal is more than
Sine wave signal corresponding to phase in the same time instantaneous voltage when, control PPG shut-off outputs are to adjust the every of power switch pipe
Secondary service time, so that the waveform envelope of operating current keeps one with the current waveform envelope corresponding to default sine wave signal
Cause, so that change the frequency characteristic of the operating current of electromagnetic heater, and then it is special to change the frequency for the noise for being delivered to pan
Property so that the heating lower noise of pan, lift the experience of user.
In the description of the invention, it is to be understood that term " " center ", " longitudinal direction ", " transverse direction ", " length ", " width ",
" thickness ", " on ", " under ", "front", "rear", "left", "right", " vertical ", " level ", " top ", " bottom " " interior ", " outer ",
The orientation or position relationship of the instruction such as " clockwise ", " counterclockwise ", " axial direction ", " radial direction ", " circumference " are based on shown in the drawings
Orientation or position relationship, are for only for ease of the description present invention and simplify description, rather than indicate or imply signified device or
Element must have specific orientation, with specific azimuth configuration and operation, therefore be not considered as limiting the invention.
In addition, term " first ", " second " be only used for describe purpose, and it is not intended that indicate or imply relative importance or
The implicit quantity for indicating indicated technical characteristic.Thus, " first " is defined, the feature of " second " can be expressed or hidden
Include at least one this feature containing ground.In the description of the invention, " multiple " are meant that at least two, such as two, three
It is individual etc., unless otherwise specifically defined.
In the present invention, unless otherwise clearly defined and limited, the art such as term " installation ", " connected ", " connection ", " fixation "
Language should be interpreted broadly, for example, it may be fixedly connected or be detachably connected, or integrally；Can be machinery
Connection or electrical connection；Can be joined directly together, can also be indirectly connected to by intermediary, can be two members
The interaction relationship of connection or two elements inside part, unless otherwise clear and definite restriction.For the ordinary skill of this area
For personnel, the concrete meaning of above-mentioned term in the present invention can be understood as the case may be.
In the present invention, unless otherwise clearly defined and limited, fisrt feature can be "above" or "below" second feature
First and second features are directly contacted, or the first and second features pass through intermediary mediate contact.Moreover, first is special
Levy second feature " on ", " top " and " above " but fisrt feature directly over second feature or oblique upper, or only
Only represent that fisrt feature level height is higher than second feature.Fisrt feature second feature " under ", " lower section " and " below "
Can be fisrt feature immediately below second feature or obliquely downward, or be merely representative of fisrt feature level height less than second
Feature.
In the description of this specification, reference term " one embodiment ", " some embodiments ", " example ", " specific example ",
Or the description of " some examples " etc. means to combine specific features, structure, material or the feature bag that the embodiment or example are described
It is contained at least one embodiment of the present invention or example.In this manual, to the schematic representation of above-mentioned term necessarily
It is directed to identical embodiment or example.Moreover, specific features, structure, material or the feature of description can be any
Combined in an appropriate manner in individual or multiple embodiments or example.In addition, in the case of not conflicting, the skill of this area
Not be the same as Example or the feature of example and non-be the same as Example or example described in this specification can be combined by art personnel
And combination.
Although embodiments of the invention have been shown and described above, it is to be understood that above-described embodiment be it is exemplary,
It is not considered as limiting the invention, one of ordinary skill in the art within the scope of the invention can be to above-described embodiment
It is changed, changes, replacing and modification.
Claims (10)
1. a kind of method for noise reduction control of electromagnetic heater, it is characterised in that comprise the following steps：
The operating current of the electromagnetic heater is sampled to obtain current sampling signal；
When controlling PPG output control signals to control that power switch pipe is opened in the electromagnetic heater, to the electric current
Sampled signal is compared with default sine wave signal；
When the magnitude of voltage of the current sampling signal is more than the phase voltage transient in the same time corresponding to the default sine wave signal
During value, the PPG shut-offs output is controlled to adjust each service time of the power switch pipe, so that the operating current
Waveform envelope be consistent with the current waveform envelope corresponding to the default sine wave signal.
2. the method for noise reduction control of electromagnetic heater according to claim 1, it is characterised in that pass through comparator pair
The current sampling signal is compared with default sine wave signal, wherein,
When the comparator output switching activity signal, the PPG shut-offs output can be directly controlled, or after delay preset time
Control the PPG shut-offs output.
3. the method for noise reduction control of electromagnetic heater according to claim 1, it is characterised in that it is described it is default just
String ripple signal is the sine wave of 2 times of electric main frequencies.
4. the method for noise reduction control of electromagnetic heater according to claim 3, it is characterised in that in described 2 times friendships
The pulse width of the control signal of the PPG outputs first becomes in each cycle for the sine wave for flowing mains frequency diminishes greatly again.
5. the method for noise reduction control of electromagnetic heater according to claim 4, it is characterised in that wherein, described 2
The crest value correspondence maximum pulse of the sine wave of times electric main frequency, the sine wave of 2 times of electric main frequencies
Valley value correspondence minimum pulse width.
6. a kind of electromagnetic heater, it is characterised in that including：
Current sampling unit, the current sampling unit is used to sample to obtain to the operating current of the electromagnetic heater
Obtain current sampling signal；
Resonance heating unit；
Rectification filtering unit, the rectification filtering unit is used to carry out resonance described in rectifying and wave-filtering treatment and supplied to electric main
Heating unit；
Power switch pipe, the power switch pipe is used to control the resonance heating unit to carry out resonant operational；
Driver element, the driver element is used to drive turning on and off for the power switch pipe；
Comparing unit, the comparing unit is used to be compared the current sampling signal with default sine wave signal；
Main control unit, the main control unit is used to control PPG to output control signals to the driver element to open the power
Close pipe be controlled, and the current sampling signal magnitude of voltage be more than the default sine wave signal corresponding to it is identical
The PPG shut-offs output is controlled during moment instantaneous voltage to adjust each service time of the power switch pipe, so that institute
The waveform envelope and the current waveform envelope corresponding to the default sine wave signal for stating operating current are consistent.
7. electromagnetic heater according to claim 6, it is characterised in that the comparing unit includes comparator, its
In, when the comparator output switching activity signal, the main control unit can directly control the PPG shut-offs output, Huo Zheyan
The PPG shut-offs output is controlled after slow preset time.
8. electromagnetic heater according to claim 6, it is characterised in that the default sine wave signal is 2 times
The sine wave of electric main frequency.
9. electromagnetic heater according to claim 8, it is characterised in that in 2 times of electric main frequencies just
The pulse width of the control signal of the PPG outputs first becomes in each cycle of string ripple diminishes greatly again.
10. electromagnetic heater according to claim 9, it is characterised in that wherein, 2 times of electric mains frequency
The crest value correspondence maximum pulse of the sine wave of rate, the valley value correspondence of the sine wave of 2 times of electric main frequencies is most
Small pulse width.
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| CN201610072354.6A CN107027201B (en) | 2016-02-02 | 2016-02-02 | Electromagnetic heating device and noise reduction control method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107949090A (en) * | 2017-09-11 | 2018-04-20 | 中山市科卓尔电器有限公司 | A kind of frequency hopping power driving circuit and method |
| CN109358537A (en) * | 2018-09-30 | 2019-02-19 | 珠海格力电器股份有限公司 | Control system and control method for reducing noise of electromagnetic cooking appliance and cooking appliance |
| CN109561531A (en) * | 2017-09-25 | 2019-04-02 | 佛山市顺德区美的电热电器制造有限公司 | The drive dynamic control device and method of electromagnetic heating apparatus and its power switch tube |
| CN110944420A (en) * | 2018-09-21 | 2020-03-31 | 深圳市鑫汇科股份有限公司 | Electromagnetic heating device and heating control method thereof |
| CN114698166A (en) * | 2020-12-29 | 2022-07-01 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating apparatus, noise suppression method, heating control system, and storage medium |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107949090A (en) * | 2017-09-11 | 2018-04-20 | 中山市科卓尔电器有限公司 | A kind of frequency hopping power driving circuit and method |
| CN107949090B (en) * | 2017-09-11 | 2018-10-09 | 中山市科卓尔电器有限公司 | A kind of frequency hopping power driving circuit and method |
| CN109561531A (en) * | 2017-09-25 | 2019-04-02 | 佛山市顺德区美的电热电器制造有限公司 | The drive dynamic control device and method of electromagnetic heating apparatus and its power switch tube |
| CN109561531B (en) * | 2017-09-25 | 2021-04-20 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating equipment and driving control device and method of power switch tube of electromagnetic heating equipment |
| CN110944420A (en) * | 2018-09-21 | 2020-03-31 | 深圳市鑫汇科股份有限公司 | Electromagnetic heating device and heating control method thereof |
| CN109358537A (en) * | 2018-09-30 | 2019-02-19 | 珠海格力电器股份有限公司 | Control system and control method for reducing noise of electromagnetic cooking appliance and cooking appliance |
| CN114698166A (en) * | 2020-12-29 | 2022-07-01 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating apparatus, noise suppression method, heating control system, and storage medium |
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