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    • 专利摘要:
    Synchronism and power control method for resonant power inverters (3), based on the use of an algorithm of the PLL type (10) capable of estimating the phase of an alternating signal from the oscillator (4), chosen as the synchronism signal, and consisting of the use of said phase as the basis for the construction of advanced or delayed carrier signals that allow the generation of the firing pulses of the inverter bridge transistors (3). (Machine-translation by Google Translate, not legally binding)
    公开号:ES2762299A1
    申请号:ES201831129
    申请日:2018-11-21
    公开日:2020-05-22
    发明作者:Huerta Jose Miguel Espi；Moreno Jaime Castello；Sanchis Cesar Manuel Cases
    申请人:GH Electrotermia SA；
    IPC主号:
    专利说明:

    [0002] Synchronism method and power control for a resonant power inverter of an induction heating generator
    [0004] Object of the invention
    [0006] The present invention, as expressed in the statement of this specification, refers to a method of synchronization and power control for resonant power inverters, based on the use of an algorithm of the PLL type (from English, Phase- Locked Loop) capable of estimating the phase of an alternate oscillator signal, chosen as the synchronization signal, and consisting of the use of said phase as the basis for the construction of advanced or delayed carrier signals that allow the generation of the trigger pulses of the inverter bridge transistors.
    [0008] The invention is applicable to all types of generators for induction heating, and allows a fast resonance tuning, both series and parallel, as well as the tuning of the two resonance frequencies of the bifrequency generators.
    [0010] The invention establishes how, from the synchronization phase provided by the PLL, carrier signals can be constructed for the usual types of control: frequency variation or FM ( Frequency Modulation), pulse density variation or PDM (from the English, Pulse Density Modulation), Pulse Width Modulation (PWM ), both centered and phase shift or PS ( Phase Shift), and bi-frequency control. For each type of generator, it is determined which oscillator signals can be used as input timing signals to the PLL, and then control is resolved by any of the mentioned methods.
    [0012] By means of the solution proposed in the invention, a notable reduction in response times in power generation is achieved. This allows surface heating of small parts, where the diffusion of heat into the part occurs very quickly, applying power pulses of very short duration.
    [0013] It also allows better synchronization in PDM control, where the frequency of the current oscillation changes rapidly between the value of the switching frequency when pulses are applied with the inverter, and the resonance value when no pulses are applied. On the other hand, the use of this type of PLL's in generators for induction heating makes it possible to solve the control of the generator within the synchronous reference frame or "dq" (from English, Direct Quadrature).
    [0015] The synchronism and power control method object of the present disclosure has application in the field of the industry dedicated to the design and commercialization of resonant commutated converters, and more specifically, in the industry dedicated to the design, manufacture and operation of heating generators by induction for metallurgy.
    [0017] Technical problem to be solved and Background of the invention
    [0019] Induction heating generators use timing mechanisms to tune into the resonator frequency of the oscillator. The current synchronization methods can be classified into two types:
    [0021] a) the traditional method based on phase detector plus controlled oscillator or VCO (of English, Voltage Controlled Oscillator). [Surge Analysis of Induction Heating Power Supply With PLL. Mu-Ping Chen, Jan-Ku Chen, Katsuaki Murata, Masatoshi Nakahara and Koosuke Harada. IEEE Transactions on Power Electronics, vol. 16, no. 5, September 2001.], and;
    [0023] b) self-oscillating methods. For more information, you can consult the publications:
    [0025] - Tunable Self-Oscillating Switching Technique for Current Source Induction Heating Systems. Alireza Namadmalan and Javad S. Moghani. IEEE Transactions On Industrial Electronics, vol. 61, no. 5, May 2014.
    [0027] Self-Oscillating Tuning Loops for Series Resonant Inductive Power Transfer Systems. Alireza Namadmalan. IEEE Transactions on Power Electronics, vol. 31, no. 10, October 2016.
    [0028] - Universal Tuning System for Series-Resonant Induction Heating Applications. Alireza Namadmalan. IEEE Transactions on Industrial Electronics, vol. 64, no.4, April 2017.
    [0030] In the first case, the phase shift detector receives the voltage and current inputs from the inverter, and calculates the phase shift between the two. This phase shift is integrated and brought to the VCO, which modifies the switching frequency. By changing the frequency, and depending on the parameters of the oscillator, the offset is modified. When the frequency stabilizes, the integrator ensures that the offset is zero, indicating that the resonance has been tuned. There are variants of this method, but they all form a phase -locked loop or PLL ( Phase-Locked Loop) in which the oscillator itself intervenes, limiting the tuning speed. As a consequence, the search time for tuning at generator start-up is high, which prevents rapid application of power. This is important in surface heating of small parts, where the heat diffusion inside the part is very fast. To avoid this diffusion, the heating power should be applied in the form of a very short pulse and cool down rapidly. Another consequence is the difficulty in tuning signals whose frequency changes rapidly, as occurs in the PDM ( Pulse Density Modulation) control with small modulation indices and short cycles, where the frequency changes between the switching value and the resonance value in a few cycles.
    [0032] On the other hand, the most recent self-oscillating synchronism methods determine the switching instants from the zero crossings of the synchronization signal (current in the series inverter or voltage in the parallel). In the serial generator, to advance the commutations with respect to the current and thus guarantee the inductive behavior of the oscillator, a phase advance network is inserted between the current measurement and the zero crossing detector. Adjusting the lead angle is done using a digital potentiometer commanded from the control unit. The advantage of the method is that, by setting an angle close to zero, the synchronism is instantaneous, allowing rapid power generation at startup. The disadvantages are, among others, the limited range of lead angles that can be achieved, the dependence of the angle on frequency, the dynamic response of the lead network to a change in the value of its potentiometer, the difficulty in compensating for delays switching in high frequency applications, and the sensitivity of the zero crossing detector to the noise present in the measurement of the synchronization signal, which is amplified by the lead network itself. Although they could be done Zero crossing comparisons with hysteresis as a solution to the noise problem, this generates an angular delay dependent on the amplitude and frequency of the synchronization signal that is difficult to compensate.
    [0034] Description of the Invention
    [0036] In order to achieve fast resonance tuning that allows power to be applied in very short response times and without the problems described above, the present disclosure describes a novel method of timing and power control for induction heating resonant inverters .
    [0038] The method of the invention is applied to induction heating generators including an inverter, a heating inductor and an oscillator.
    [0040] The method of the invention comprises generating tripping pulses of the power inverter transistors by comparing a first triangular carrier signal with a tripping threshold, the tripping threshold being approximately the average value between the extreme values of the first carrier signal .
    [0042] The trigger pulses are advanced / delayed by a switching angle 0 with respect to an alternate oscillator signal chosen as the sync signal. Said advance / delay can be performed either by advancing / retarding the first carrier signal by an angle 0 without altering the trigger threshold or by reducing / increasing the trigger threshold and the ends of the first carrier signal by a value of 0.
    [0044] The first forward / backward carrier signal is the phase estimate of the sync signal provided by a PLL algorithm.
    [0046] The advance / delay of the first carrier signal consists of adding / subtracting an angle 0 from the phase estimate.
    [0048] Control of the power by frequency variation is carried out by changing the value of 0 .
    [0050] According to a possible embodiment, the method of the invention comprises selecting the inverter current or the voltage of a series capacitor as synchronization signal. the case of a serial generator; or the voltage of a parallel capacitor in a parallel generator; either the series current or the voltage of the parallel capacitor in an LLC three-element series-parallel generator.
    [0052] According to a possible embodiment, the method comprises transmitting pulses to the oscillator with the constant 0 value that determines the operation in resonance, but avoiding the transmission of a certain number of pulses to the oscillator, so that the power varies according to the density of the pulses applied to the oscillator.
    [0054] Also, according to a possible embodiment, the timing and power control method for a resonant power inverter of an induction heating generator comprises using the power inverter in full bridge configuration, and firing one of the two branches of the inverter with one angle 0 to set the operating frequency, and the other with a delay from the first. This delay is obtained by comparing a second carrier signal with a frequency equal to twice the frequency of the first carrier signal and an offset threshold 9. The second carrier signal may be symmetric or anti-symmetric but coincides with the first carrier signal. at the beginning of its cycle. Changing the offset threshold cp produces power changes by modulating the width of the pulses applied to the oscillator.
    [0056] Preferably, according to a possible embodiment, the method comprises generating a current through the heating inductor with two frequency components using two power inverters and two PLL algorithms. Each PLL algorithm receives a sync signal from the oscillator, one being low frequency and the other high frequency. The PLL outputs are used to build low and high frequency carrier signals. The power controls of the low and high frequency components can be carried out independently by means of frequency variation by changing the angle 0, pulse density with constant angle 0, pulse width modulation by changing the cp offset, or also in the case of the parallel generator, from the input rectifiers keeping 0 constant.
    [0058] Also, according to a possible alternative embodiment to that mentioned in the previous paragraph, the method comprises generating a current through the heating inductor with two frequency components using a single full-bridged power inverter and two PLL algorithms. These algorithms receive from oscillator its low frequency and high frequency sync signals. The high frequency PLL output is used to construct the second symmetric / anti-symmetric dual frequency carrier signal. The low-frequency PLL output is used to construct two low-frequency, push-pull, sinusoidal modulator signals. The trigger pulses to the transistors are determined by comparing the second dual frequency carrier signal and the modulator signals, one of the modulator signals being used to generate the positive pulses to the oscillator and the other modulator signal to generate the negative pulses. The low frequency power is controlled by varying the amplitude of the modulating signals, and the high frequency power is controlled by varying the switching angle 0 on the serial generator, or from the rectifier on the parallel generator.
    [0060] Thus, according to a possible embodiment, the method comprises selecting as synchronization signals:
    [0062] - the output currents of the high and low frequency inverters, or the voltages of the high and low frequency capacitors, in a two-frequency series generator with two power inverters, or;
    [0064] - the current through the low frequency coil or the low frequency capacitor voltage, and the high frequency current or the high frequency capacitor voltage, in a bifrequency series generator with a single power inverter, or;
    [0066] - the voltages of the high and low frequency capacitors, or the high and low frequency currents, in a two-frequency parallel generator with two power inverters, or;
    [0068] - the current through the low-frequency coil or the voltage of the low-frequency capacitor, and the current through the high-frequency capacitor or the voltage of the heating coil, in a dual-frequency parallel generator with a single power inverter.
    [0070] It is noted that in the current state of the art, the aforementioned PLL algorithms are already commonly used in low-frequency applications, such as power connected to the electrical network and converters for power generation or traction with an electrical machine. Therefore, it should be emphasized that the invention does not consist of the PLL itself, but of the use made of the estimated phase with it to generate the trigger pulses in a resonant inverter.
    [0072] Note also the difference between the aforementioned phase shift detector and the estimation of the phase of a signal. While the phase shift detector would give a constant amount to two signals of the same frequency and constant phase shift, phase estimation gives us the angular position of the signals in real time, which not only allows us to calculate the phase shift (by subtracting ) but also allows us to plan events (such as transistor switching) dependent on the angular position of the signals.
    [0074] The synchronism method proposed in the invention is of the self-oscillating type, but it is fully digital in implementation. It allows for the advanced or delayed generation of the trigger pulses with respect to the synchronism signal, precisely and instantaneously. Furthermore, since the PLL provides the angular information at all times, pulses can be generated at will throughout the sync signal cycle. Thanks to this, the method can be used to generate the trigger signals of the most common control strategies: frequency variation (FM), pulse density modulation (PDM), pulse width modulation (both by phase shift PS such as centered PWM), Third Harmonic Operation (THO) control, dual frequency control, etc.
    [0076] Since the PLL algorithm is also capable of estimating the frequency oo of the sync signal, it is easy to compensate for constant time delays td, such as delay in transistor trips or measurement delays, by adding the lead term oo * td .
    [0078] Another advantage is that the method is not very sensitive to measurement noise, since the PLL algorithm performs an inherent bandpass filtering to extract the fundamental harmonic of the synchronization signal.
    [0080] Finally, the use of a PLL like the one mentioned has the additional advantage that it opens the door to the implementation of the controls of the generators in the synchronous or "dq" frame of reference. In this frame of reference, the amplitudes or Envelopes of the oscillator alternate signals are calculated without the need for circuitry to detect the peak value.
    [0082] Below, to facilitate a better understanding of this specification, and forming an integral part thereof, some figures are attached which, by way of illustration and not limitation, represent the object of the invention.
    [0084] Brief description of the figures
    [0086] As part of the explanation of at least one exemplary embodiment of the timing method for induction heating resonant inverters object of the present disclosure, the following figures have been included.
    [0088] Figure 1A: Shows the structure of an induction heating generator.
    [0090] Figure 1B: Shows the basic structure of the inverter control using the method of the present invention.
    [0092] Figure 2A: Shows a first instant of frequency variation applied to the oscillator, according to a first embodiment of the method of the invention.
    [0094] Figure 2B: Shows a second instant of frequency variation applied to the oscillator, according to the first embodiment of the method of the invention.
    [0096] Figure 3A: Shows a first instant of frequency variation applied to the oscillator, according to a second embodiment of the method of the invention.
    [0098] Figure 3B: Shows a second instant of frequency variation applied to the oscillator, according to the second embodiment of the method of the invention.
    [0100] Figure 4: Shows an embodiment of the control by pulse density modulation (PDM), according to the method of the invention.
    [0102] Figure 5: Shows an embodiment of the use of a PLL to perform a pulse width modulation (PWM) by phase shift, according to the method of the invention.
    [0103] Figure 6: Shows an embodiment of the generation of centered PWM modulation patterns, according to the method of the invention.
    [0105] Figure 7: Shows an embodiment of the generation of bi-frequency modulation patterns, according to the method of the invention.
    [0107] Figure 8A: Shows a schematic representation of a series type induction heating generator.
    [0109] Figure 8B: Shows a schematic representation of a parallel type induction heating generator.
    [0111] Figure 8C: Shows a schematic representation of a three-element induction heating generator, LLC.
    [0113] Figure 9A: Shows a schematic representation of a serial dual-frequency induction heating generator with two power inverters.
    [0115] Figure 9B: Shows a schematic representation of a dual-frequency induction heating serial generator with a single power inverter.
    [0117] Figure 10A: Shows a schematic representation of a dual frequency induction heating parallel generator with two power inverters.
    [0119] Figure 10B: Shows a schematic representation of a dual frequency induction heating parallel generator with a single power inverter.
    [0121] Detailed description
    [0123] The present disclosure relates, as already mentioned above, to a timing and power control method for induction heating resonant inverters.
    [0125] Figure 1A shows the structure of an induction heating generator, formed by the heating inductor (5) and the box (7), which contains the rectifier (2) of the mains voltage (1), the inverter bridge (3), the oscillator (4), and the control circuit (6) of the inverter (and of the rectifier in the case of the parallel generator).
    [0127] Figure 1B shows the basic structure of the inverter control using the proposed strategy. The inputs to the control are the measurements (8) and the command or limit signals (13). Among all the measurements, an oscillator AC signal is selected as the synchronism signal (9) (two signals in the case of the bifrequency generator). The PLL algorithm (10) extracts the frequency oo and the phase (11) of the synchronization signal, the latter going through values between 0 and 360 degrees in a complete cycle. Therefore, the numerical representation of this phase as a function of time has a sawtooth shape between 0 and 360 degrees. The regulation / limitation block (12) determines the lead / lag angle 0 and, in certain types of control, also the angle cp for pulse width modulation, in such a way that the heating power is regulated and the oscillator variables within acceptable ranges. Finally, the signal generator block (14) generates the trip signals (15) of the inverter transistors from the PLL phase and angles 0 and 9.
    [0129] Figures 2 and 3 correspond to a serial generator, and show two possible embodiments of the invention. The synchronization phase calculated by the PLL (20, 25, 30, 35), has been represented between 0 degrees and 360 degrees for convenience and without loss of generality, although in the actual implementation in a processor these angles would be proportional value codes to those indicated. Also seeking simplicity in the description, the zero crossings of the synchronization signal (22, 27, 32, 37) have been made to coincide with the steps of the phase (20, 25, 30, 35) by 0, 180 and 360 degrees, when the PLL is stabilized. Although a different implementation of the PLL can give different phases at zero crossings, it would be enough to add or subtract a constant angle to the phase of the PLL to reproduce the situation that is exposed. These figures are explained in detail later.
    [0131] In Figures 2A and 2B, the advance / delay of the pulses (23, 28) applied to the oscillator with respect to the current (22, 27), is achieved by respectively adding / subtracting the desired angle 0 to the synchronization phase (20, 25) given by the PLL, obtaining the triangular carrier signal (21, 26), and comparing it with the intermediate threshold of 180 degrees.
    [0133] l l
    [0134] Specifically, Figure 2A shows a sudden change, at time t0, from a value 0 = 0 to another 0 = 80 degrees, which produces the advance of the pulses and the increase in frequency from the operation in resonance to the operation at high frequency. Subsequently, in Figure 2B, the resonance is tuned again, restoring the value 0 = 0 at time t1.
    [0136] An alternative way of performing the same action is shown in Figures 3A and 3B. Here, the lead / lag of the trigger pulses is achieved by respectively subtracting / adding the desired angle 0 to the 180 degree level, resulting in a variable comparison threshold with 0. Now, the triangular carrier signal (31, 36) being compared with the threshold, it coincides with the synchronism phase (30, 35), except for its lower and upper limits, which must be modified in the same way as the threshold to guarantee pulses with the same duration at low state as at high state.
    [0138] Thus, in Figure 3A, at the time t0, both the comparison threshold and the limits of the carrier (36) are reduced by an amount 0 = 80 degrees, which causes the pulses to advance and the operation to change from resonance to high frequency. The effects on the inverter voltage (33) and current (32) are identical to those shown in Figure 2A. Subsequently, in Figure 3B, 0 = 0 degrees is reapplied at time t1, which restores the operation in resonance. Again, the results on the inverter voltage (38) and current (37) are identical to those obtained in Figure 2B, demonstrating that the methods of Figures 2 and 3 are equivalent.
    [0140] Figures 4, 5, 6 and 7 show application examples of the invention, where it is shown graphically how to generate the inverter pulses in the PDM, PS (Phase-Shift), centered PWM and bifrequency control, respectively. In all of them, the strategy of Figure 2 has been chosen to advance the firing pulses of the transistors with respect to the current.
    [0142] Figure 4 shows the control by pulse density modulation or PDM applied to a serial generator. The resonance operation is guaranteed by adding a small angle 0 to the synchronization phase (40) obtained with the PLL, to obtain the carrier signal (41) slightly ahead. In this way the pulses (43) are always applied slightly ahead of the current (42).
    [0143] Figure 5 shows how the PLL information can be used to perform PWM pulse width modulation using the Phase Shift technique. In this case, it is necessary to build a triangular carrier signal (51) twice the frequency, starting from the synchronization phase (50). The width of the pulses transmitted by the inverter is obtained from the intersection of the carrier (51) with the threshold (52) (value of cp). Although for simplicity in this example, the carrier (51) has not been advanced with respect to the synchronization phase (50) (that is, it has been assumed 0 = 0), in reality, lags 0 and cp pulse widths can be generated simultaneously and Independent.
    [0145] Figure 6 shows how centered PWM modulation patterns can be generated. Again, for simplicity, 0 = 0 has been assumed. In this case, it is necessary to build a double but symmetric triangular carrier (62), from the double frequency anti-symmetric triangular signal (61) that is used in the PS control. The width of the pulses is determined by intersection of the symmetric carrier (62) with the threshold (63).
    [0147] Figure 7 shows how bi-frequency modulation patterns can be generated. Centered PWM has been used in the figure, although it can also be done with PWM-PS. Two complementary and sinusoidal modulating signals are used (73, 74), which alternate each half cycle to determine the pulse width by comparison with the symmetric carrier (72). The result is a voltage (76) in the inverter and a current (75) where the low and high frequency components are appreciated. This type of modulation is used in bi-frequency generators with a single power inverter.
    [0149] Finally, Figures 8, 9 and 10 show the configurations commonly used in induction heating, and each of them identifies the oscillator variables that could be used as synchronization signals at the input of the PLL to implement the invention. How these signals should be treated is explained below.
    [0151] Figure 8A shows the series generator. The usual measurements can be used as synchronization signals: the inverter current (80) and the capacitor voltage (81). In the case of using the capacitor voltage, which is 90 degrees behind the current, you must add 90 degrees to the synchronization phase obtained by the PLL, or use a PLL implementation that provides the additional 90 degrees.
    [0153] The parallel type generator is shown in Figure 8B. The usual measurement is the voltage across the capacitor (82), which should be used as a sync signal. To operate slightly below resonance, the carrier signal is delayed by a small 0 angle.
    [0155] Figure 8C shows the LLC three-element generator. The current (84) and the voltage of the capacitor (83) are usually measured. If the latter is used as a synchronization signal, the series resonance is tuned when the pulses are advanced by an angle 0 = 90 degrees with respect to the voltage in the capacitor.
    [0157] Figures 9A and 9B show the two-frequency series generators, with two power inverters (Figure 9A) and with a single power inverter (Figure 9B).
    [0159] In Figure 9A, series bifrequency with two inverters, the low frequency current (90) and the high frequency current (92), and the voltages of the low (91) and high (93) frequency capacitors are usually measured. Two PLLs must be used, one connected to (90) or (91) to tune the low frequency, and one connected to (92) or (93) to tune the high frequency. If a PLL is connected to the voltage of a capacitor, the phase obtained must be advanced 90 degrees. Each PLL provides a synchronous phase in a triangular shape, one low and one high frequency, from which the commutations of the low and high frequency inverters are determined according to the described method. The low and high frequency current amplitudes can be independently controlled on each inverter by any of the mentioned control methods.
    [0161] In Figure 9B, serial bifrequency with a single power inverter, low (95) and high (97) frequency currents, and low (96) and high (98) frequency voltages can be measured. The low frequency PLL can use (95) or (96), and the high frequency PLL can use (97) or (98). Again remember that if the voltages (96) or (98) are used, the synchronization phases obtained with the PLL should be added 90 degrees. The low-frequency PLL provides a phase whose sine function enables the modulating signals (73, 74) of Figure 7 to be constructed. The amplitude of these signals Modulators determines the amplitude of the generated low frequency current. On the other hand, the high frequency PLL determines the synchronization phase (70) of Figure 7, from which the anti-symmetric carrier (71) can be constructed if PS control is used, or the symmetric carrier (72 ) if using centered PWM. The lead angle 0 of the high frequency carrier determines the amplitude of the high frequency current.
    [0163] Finally, Figures 10A and 10B show the dual frequency parallel generators, with two inverters (Figure 10A) and with a single inverter (Figure 10B).
    [0165] Figure 10A shows the parallel bifrequency generator with two inverters. Low (101) and high (103) frequency currents, and low (100) and high (102) frequency voltages can be measured. The two inverters switch current pulses in resonance, slightly delayed with respect to (100) and (102), with a small delay angle 0. From the rectifier of each converter the amplitude of the low and high frequency current pulses is modified, to independently regulate the resulting voltage amplitude of low (100) and high (102) frequency.
    [0167] In Figure 10B, parallel bifrequency with a single inverter, low (105) and high (107) frequency currents, and low (106) and high (108) frequency voltages can be measured. The low-frequency PLL provides a phase whose sine function allows the necessary two sinusoidal modulating signals to be built, and whose amplitude allows controlling the low-frequency amplitude of the resulting voltage in (106). The high-frequency PLL allows you to build the anti-symmetric and symmetric dual-frequency carrier signals, using a delay angle 0 close to zero. The intersections between the carrier and the modulators determine the switching instants of the inverter transistors to generate the dual frequency switched current pattern. The amplitude of the resulting high frequency voltage at (108) is controlled from the rectifier, modifying the amplitude of the current pulses. This also affects the resulting low-frequency voltage amplitude, forcing continuous action on the amplitude of the modulating signals.
    权利要求:
    Claims (7)
    [1]
    1. Synchronism and power control method for a resonant power inverter (3) of an induction heating generator, wherein said induction heating generator comprises the power inverter (3), a heating inductor (5) and an oscillator (4), characterized in that it comprises generating trip pulses (15) of the transistors of the power inverter (3) by comparing a first triangular carrier signal (21, 26, 31, 36, 41) with a threshold trigger (24, 29, 34, 39, 44), where the trigger threshold (24, 29, 34, 39, 44) is approximately the average value between the extreme values of the first carrier signal (21, 26, 31 , 36, 41), where said trigger pulses (15) are advanced / delayed by a switching angle 0 with respect to an alternate oscillator signal chosen as the synchronization signal (80, 81, 82, 83, 84, 90, 91, 92, 93, 95, 96, 97, 98, 100, 101, 102, 103, 105, 106, 107, 108), where said advance / delay can be done well ad setting / delaying the first carrier signal (21, 26, 31, 36, 41) an angle 0 without altering the trigger threshold (24, 29, 34, 39, 44) or reducing / increasing the trigger threshold (24, 29, 34, 39, 44) and the ends of the first carrier signal (21, 26, 31, 36, 41) at a value of 0, where the first carrier signal (21, 26, 31, 36, 41) without overtaking / delay is the estimation of the phase (11, 20, 25, 30, 35, 40, 50, 60, 70) of the sync signal (80, 81, 82, 83, 84, 90, 91, 92, 93 , 95, 96, 97, 98, 100, 101, 102, 103, 105, 106, 107, 108) which provides a PLL algorithm (10), where the lead / lag of the first carrier signal (21, 26, 31 , 36, 41) consists of adding / subtracting to the phase estimate (11, 20, 25, 30, 35, 40, 50, 60, 70) an angle 0, and where the power control by frequency variation it is done by changing the value of 0.
    [2]
    Synchronism method and power control for a resonant power inverter of an induction heating generator according to claim 1, characterized in that it comprises selecting the inverter current (80) or the voltage of a serial capacitor as the synchronization signal. (81) in the case of a series generator, the voltage of a parallel capacitor (82) in a parallel generator, and the series current (84) or the voltage of the parallel capacitor (83) in a three-element series-parallel generator LLC.
    [3]
    3. Synchronism and power control method for a resonant power inverter of an induction heating generator according to claim 1, characterized in that it comprises transmitting pulses to the oscillator with a constant value of 0 that determines the operation in resonance, but avoiding the transmission of a certain amount of pulses to the oscillator, so that the power varies according to the density of the pulses applied to the oscillator.
    [4]
    4. Synchronism and power control method for a resonant power inverter of an induction heating generator according to claim 1, characterized in that it comprises using the full bridge power inverter where one of the two branches of the inverter is triggered with An angle 0 to fix the operating frequency, and the other branch is triggered with a delay with respect to the first one, where said delay is obtained by comparison between a second carrier signal (62, 72) of a frequency equal to twice the frequency of the first carrier signal and a lag threshold cp (52, 63), where the second carrier signal can be symmetric or anti-symmetric but coincides with the first carrier signal at the beginning of its cycle, and where the change in the lag threshold cp produces power changes by modulating the width of the pulses applied to the oscillator.
    [5]
    5. Synchronism and power control method for a resonant power inverter of an induction heating generator according to any of claims 1, 3 or 4, characterized in that it comprises generating a current through the heating inductor with two frequency components using two power inverters and two PLL algorithms, where each PLL algorithm receives a synchronism signal from the oscillator, one being a low frequency (90, 91, 100, 101) and the other a high frequency (92, 93, 102, 103), where the PLL outputs are used to build low and high frequency carrier signals, and where the power controls of the low and high frequency components can be performed independently by frequency variation by changing the angle 0, pulse density with constant 0 angle, pulse width modulation by changing the cp offset, or also, in the case of the parallel generator, from the input rectifiers keeping 0 constant.
    [6]
    6. Synchronism and power control method for a resonant power inverter of an induction heating generator according to claim 4, characterized in that it comprises generating a current through the heating inductor with two frequency components using a single power inverter in full bridge and two PLL algorithms, where said algorithms receive their low frequency (95, 96, 105, 106) and high frequency (97, 98, 107, 108) synchronization signals from the oscillator, where the high frequency PLL output is used to construct the second symmetric / anti-symmetric dual frequency carrier signal (72), where the low frequency PLL output is used to construct two low-frequency sinusoidal and push-pull modulator signals (73, 74), where the Trigger pulses to the transistors are determined by comparing the second dual frequency carrier signal (72) and the modulator signals (73, 74), using e one of the modulating signals (73) to generate the positive pulses to the oscillator and the other modulating signal (74) to generate the negative pulses, and where the low frequency power is controlled by varying the amplitude of the modulating signals, and the power High frequency is controlled by varying the switching angle 0 on the serial generator, or from the rectifier on the parallel generator.
    [7]
    7. Synchronization method and power control for a resonant power inverter of an induction heating generator according to claims 5 and 6, characterized in that it comprises selecting as synchronism signals a low frequency current (90) or a voltage of low frequency capacitor (91) and a high frequency current (92) or a high frequency capacitor voltage (93) in a bifrequency series generator with two power inverters, a low frequency current (95) or a voltage of low frequency capacitor (96) and a high frequency current (97) or a high frequency capacitor voltage (98) in a bifrequency series generator with a single power inverter, a low frequency capacitor voltage (100) or a low frequency current (101) and a high frequency capacitor voltage (102) or a high frequency current (103) in a two-frequency parallel generator with two inverters power, and low frequency current (105) or low frequency capacitor voltage (106) and high frequency current (107) or high frequency voltage (108) in a dual frequency parallel generator with a single inverter power.
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    同族专利:
    公开号 | 公开日
    EP3886535A1|2021-09-29|
    EP3886535A4|2021-12-22|
    WO2020104718A1|2020-05-28|
    ES2762299B2|2020-10-20|
    引用文献:
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    EP2148551A1|2008-07-21|2010-01-27|GH Electrotermia, S.A.|Inductive heating apparatus comprising a resonant circuit with simultaneous dual frequency current output and a single inverter circuit with silicon carbide|
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    ES2626572A1|2016-01-25|2017-07-25|Universidad De Zaragoza|Dual frequency resonant power converter suitable for use in induction heating applications |
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    EP2148421A1|2008-07-21|2010-01-27|GH Electrotermia, S.A.|Pulse density modulated high efficiency converter for induction heating|
    WO2012123559A2|2011-03-16|2012-09-20|Sma Solar Technology Ag|Mains-coupled inverter, inverter arrangement and method for operating an inverter arrangement|
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    ES201831129A|ES2762299B2|2018-11-21|2018-11-21|Synchronization and power control method for a resonant power inverter of an induction heating generator|ES201831129A| ES2762299B2|2018-11-21|2018-11-21|Synchronization and power control method for a resonant power inverter of an induction heating generator|
    EP19887616.1A| EP3886535A4|2018-11-21|2019-11-06|Method of power synchronisation and control for a resonant power inverter of an induction heating generator|
    PCT/ES2019/070750| WO2020104718A1|2018-11-21|2019-11-06|Method of power synchronisation and control for a resonant power inverter of an induction heating generator|
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