US3925633A - Circuit for controlling power flow from a high frequency energy source to a plurality of high frequency loads - Google Patents

Circuit for controlling power flow from a high frequency energy source to a plurality of high frequency loads Download PDF

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US3925633A
US3925633A US503781A US50378174A US3925633A US 3925633 A US3925633 A US 3925633A US 503781 A US503781 A US 503781A US 50378174 A US50378174 A US 50378174A US 3925633 A US3925633 A US 3925633A
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source
energy
load
switching means
high frequency
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Donald F Partridge
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Priority to US503781A priority Critical patent/US3925633A/en
Priority to CA231,411A priority patent/CA989488A/en
Priority to GB30272/75A priority patent/GB1488306A/en
Priority to NL7508813A priority patent/NL7508813A/xx
Priority to DE2535637A priority patent/DE2535637C3/de
Priority to JP10715875A priority patent/JPS5539117B2/ja
Priority to FR7527319A priority patent/FR2284245A1/fr
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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
    • H05B6/062—Control, e.g. of temperature, of power for cooking plates or the like
    • H05B6/065—Control, e.g. of temperature, of power for cooking plates or the like using coordinated control of multiple induction coils
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/505—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
    • H02M7/515—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
    • H02M7/523—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only with LC-resonance circuit in the main circuit
    • H02M7/5233—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only with LC-resonance circuit in the main circuit the commutation elements being in a push-pull arrangement
    • H02M7/5236—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only with LC-resonance circuit in the main circuit the commutation elements being in a push-pull arrangement in a series push-pull arrangement

Definitions

  • ABSTRACT [52] US. Cl. 219/10.49; 219/ 10.77; 321/4 A circuit f r on rolling the level of energy transmit- [51] Int. Cl. H05B 5/04 tcd m a h gh fr q ency nergy so rce t two r [58] Field of Search 219/10 49, 10,75, 1() 77; more induction heating loads which permit the level of 321/4, 7, 60, 70 energy transmitted to the loads to be regulated with minimal switching losses and with low component [56] keferences Cited 7 costs
  • One important application of the invention is a UNITED STATES PATENTS multl-burner home-type cooking range.
  • FIG. 28 FIG. 5A
  • Induction heating is recognized as a very efficient way to change electrical energy to thermal energy because the energy is absorbed directly by the container instead of being transferred by conduction, convection and radiation as is, for instance, the case with the normal home cooking range using tubular electrical heaters. For much the same reasons induction heating is also more efficient thangas heating.
  • Still another prime objective of this invention is to provide a new type of high'frequency energy source running at the 6 to IOKW level with a new, concept of dividing and controlling the powerto several different loads (four loads with a standard cooking'range) in a way that is more efficient and less expensive that past controls attempting the same objective.
  • An inductive heating apparatus comprising a high frequency energy source and two I or inore loads adapted to absorb and be selectively heatedby the high frequency energy source.
  • the invention includes a first switching means provided for converting unidirectional potential to a high frequency energy source. This' switching means is cycled onv and off at a frequency rate substantially lower than the high second switching means to regulate the energy transmitted from the sourceto the load.
  • FIGS. 1A, 1B and 1C are circuit diagrams of the prior art
  • FIG. 2' shows selected waveforms of FIG. 1
  • FIG. 3A is a circuit diagram of a second embodiment of the prior art
  • FIGS. 38 and 3C are selected waveforms of the circuit of FIG. 3A;
  • FIG. 4 shows a first embodiment of the invention
  • FIG. 5 shows selected waveforms of FIG. 4
  • FIG; 6 is an improvement of the embodiment shown in FIG. 4;
  • FIG. 7 shows a waveform of FIG. 6
  • FIG. 8 shows another embodiment incorporating the circuits of FIG. 1 and FIG. 4;
  • FIG. 9 shows a modification of the embodiment of FIG. 8, which modification is especially applicable to home cooking ranges.
  • FIG. 1A One embodiment of the prior art is shown in FIG. 1A, in which high frequency energy, at a frequency in the order of 20,000 Hertz or higher, is used to energize an induction 'coillS (FIG. 1A) for the magnetic transfer of energy to a vessel 11 for the purpose of heating that vessel by an induction process.
  • induction 'coillS FIG. 1A
  • FIG. 1A By setting up a rapidly changing magnetic field in a manner to encompass vessel 1 1, eddy currents are induced which cause a heating of the vessel walls.
  • any material held by the vessel can be'rapidly and efficiently heated.
  • the load does not have to be a cooking pot, but such is so shown as one application 'of the present invention.
  • SCRs 13 and 14 convert the direct current energy source 10 into a high freque'ncy'source in which the tum-off time (i.e., the time the SCRs 13 and 14 are reverse biased) is independent of the resonant frequency of the load.
  • the circuit has an effective power factor of 1 since there is no reactive energy feedback to the DC source 10.
  • the gating controls for the SCRs are not shown because such controls are Well known and widely used in the industry.
  • the DC source 10 is connected in series with an interconnecting circuit means including the two SCRs 13 and 14.
  • an interconnecting circuit means including the two SCRs 13 and 14.
  • the SCR 14' is the series load circuit represented by the inductance 15 and the capacitor 12.
  • This circuit is capable of generating high frequency energy for transmission to the container 11. If the load is to be used for cooking one suitable frequency'is 20 KHz, which freterial to be heated by being located near the area of the I quency is above the normal hearing level of humans.
  • One cycle of operation of the circuit of FIG. 1A is as follows.
  • sinusoidal current flows through the following path: ground, DC source 10, SCR 13, inductance (load), capacitor 12 andback to ground.
  • the load current-during this period appears as the current in FIG. 2A from timer, to 1
  • the load current will reduce to near zero when the capacitor 12 becomes charged a maximum amount.
  • the voltage on capacitor 12 will be of a polarity as shown in FIG. 1A and larger in value than DC source 10. Since the voltage on capacitor 12 is larger than the DC source 10, the SCR 13 will become reverse biased and cease conduction.
  • the reverse voltage can remain on SCR 13 for atime that is independent of the natural resonance of the load (inductance 15 and the capacitor 12). Also during the turn-off time of SCR 13, no reverse current flows into the DC source 10. When SCR 13 has been reverse biased for a period long enough to sustain a forward voltage, SCR 14 can be caused to conduct.
  • SCRs are used by way of example but other typesof switching devices such as thyrotrons and mercury arc tubes could be used.
  • FIGS. 1B and 1C are shown other embodiments of the prior art having most components similar to those of FIG. 1A.
  • the capacitors 16 and 17 are much larger than the capacitorlZB.
  • the voltage and current waveforms of the SCRs in FIG. 1B and FIG. 1C are the same as for the embodiment of FIG. 1A.
  • the inductance 15A and 15B in FIGS. 3 and 1C are the same as in FIG. 1A.
  • the capacitance 12B of FIG. 1B is the same as the capacitance 12 of I FIG. 1A.
  • the total capacitance in FIG. 1C (12C1 and 12C2) is equal to capacitance 12 ofFIG. 1A.
  • the currents and voltages of the SCRs of FIGS 1A, 1B and 1C are all the same.
  • the operation of FIGS. 1B and 1C are similar to FIG. 1A and are well-known in the industry.
  • FIGS. 1A, 1B and 1C are shown in FIG. 2A and FIG. 2B, respectively.
  • Time t to t occurs when SCR 13 is conducting.
  • Time t to 1 occurs when SCR 13 is reverse biased.
  • the time period 2 to t exists while SCR 14 is conducting.
  • Time to r iswhen SCR 14 is reverse biased.
  • the-circuits of FIGS. 1A, 1B and 1C are especially suitable forlow voltage and low Q-type induction heating loads. r
  • a preferred method. of controlling the power delivered to the load is as follows: the high frequency inverters are turned off and on at a frequency rate substantially lower than the frequency being generated.
  • the preferred low frequency rate is in the order of 0.1 to 10 Hertz. If the low frequency rate is ,1 Hz and 50 percent power is delivered to the load (the cooking pot in preferred application), the high frequency power would be on for one-half second and off for one-half second. If percent power was required then the high frequency inverter would be on for one-fourth second and off for three-fourths second at a low frequency rate of 1 Hz.
  • FIG. 5A shows a waveform of approximately 80% power being delivered to the load.
  • the inverter is on 4 during time period 54 and off during time period 55.
  • FIG. -5 will be explained in more detail in conjunction with apreferred embodiment. It should be noted that the circuits of FIGS. 1A, 1B and 1C can be turned on at fullfrequency. They do not have to be turned'on at alow frequency and then increased in frequency. In this way. only a low tick sound is heard when the inverter turns on. With normal room noises the tick is not heard.
  • v V shows a waveform of approximately 80% power being delivered to the load.
  • the inverter is on 4 during time period 54 and off during time period 55.
  • FIG. -5 will be explained in more detail in conjunction with apreferred embodiment. It should be noted that the circuits of FIGS. 1A, 1B and 1C can be turned on at fullfrequency. They do not have to be turned'on at alow frequency and then increased in frequency. In this way.
  • FIG. 3 Shown in FIG. 3 is a second embodiment of prior art.
  • the importance of this embodiment involves the obtaining of alower voltage rise time on the switching SCRs.
  • the faster the rise time the more likely the SCRs will become conductive at an undesirable time and therefore will result'in a crowbarf effect, that is, both the SCRs will be in a conductive, mode vsimultaneously making the circuit useless for inductive heating purposes.
  • the SCR 33 is fired periodically at 21 frequency necessary to create high frequency currents in'the load 35. Between the firings of the SCR 33, the SCR 34 is fired to reverse the voltage on the capacitor 36 by current flow through the load inductor.
  • FIG. 3A Shown in FIG. 3A in solid lines is a similar waveform as that shown in FIG. 2B. In dotted lines are shown the waveforms resulting because of the effect of the inductors 31 and 32.
  • the much lower dv/dt (voltage rise time) at point A should be noted and, more importantly, is obtained without the use of dv/dt filters which otherwise can cause further power losses in the system,
  • SCR 34 can be firedj'much sooner after SCR is reverse biased in this embodiment than in the embodiment of FIG. 1A with the same turnoff time requirements. This is possible because the action of the inductors 31 and 32 keeps the SCR 33 reverse biased even when the SCR 34 is conducting. This is accomplished while maintaining the reverse time on the SCR 33 the same (i.e. as in FIG. 1A). Thus the peak current and the di/dt (current rise time) in the SCRs are less for the same power delivered. v I
  • FIG. 3C represents an example of the actual current waveforms for the circuit of FIG. 3A.
  • FIG. 3C represents an example of the actual current waveforms for the circuit of FIG. 3A.
  • the two currents are shown with and without inductors 31 and 32.
  • the load could be returned with the addition of the inductors 31 and 32 to give a similar current waveform as in FIG. 1A.
  • This would then maintain the SCR currents the same, the power delivered the same and as a further advantage, would increase the turn-off time on the SCRs 33 and 34.
  • This is achieved by firing the SCR 34 at time t (FIG. 3B) for delivering the same power and current waveform to the load but with the SCRs having a much longer turnoff time and lower dv/dt than in the previous embodiments of FIGS. 1A, 1B and 1C.
  • the waveform for this embodiment is shown in FIG. 313 as with the dotted line and arrow waveform. The turnoff time is thus increased to the time period t,
  • the combination of the two approaches can be used, i.e., the combination of the somewhat longer t and somewhat lower di/dt and peak current in thetheir forward blocking ability when they are reverse biased for one-half the period of the high frequency source.
  • This effect can be enhanced by keeping a continuous drive to the gates of the SCRs 49 and 50. The longer the tum-off time of the SCRs 46, 47, 49 and 50, the more easily the continuous conducting effect can be obtained.
  • the initial di/dt of the current i.e., the rate of rise of the current
  • the peak current is less
  • the negative di/dt near the end of the pulse is lower (which makes it easier to turn off the SCR)
  • the RMS value of the current is lower.
  • the SCRs 33 and 34 can also be built with multiple gates as is now known in the industry. By sequentially firing the individual gates, this type SCR has much higher capabilities for operating in high di/dt and/or high frequency environments than previous SCRs with the same size silicon chip.
  • FIG. 4 a first embodiment of the present invention which embodiment is an improvement over the prior art just described.
  • the individual load switching means or controls 43 and 44 in cooperation with the on-off switching means or control 45 for allowing independent regulation of the energy levels transmitted through interconnecting circuit means to the induction heating coils A and B, respectively.
  • the control 43 uti lizes a forward conducting SCR 46 and a reverse parallel connected SCR 47 having a gating control 48 for regulating the firing of the SCRs 46 and 47.
  • the control 44 includes the SCRs 49 and 50 and the gating control 53.
  • the SCRs 46, 47, 49 and 50 are standard and relatively low cost type SCRs capable of efficient operation in 'low frequency ranges.
  • the high frequency energy source 51 supplies AC current adapted to maintain each SCR in a conducting mode once a gating signal is supplied to each respective gating terminal T.
  • the SCRs 46, 47, 49 and 50 are not required to turn off at the high frequency source rate (i.e., in the order of 20 Khz or higher) but at a much lower rate (i.e., in the order of l to 10 Hertz), and more importanty are not subjected to high switching losses because once they are turned on, they do not recover the SCR 49 was momentarily reverse biased.
  • the control 52 serves as a low frequency on-off control for the high frequency energy source 51. Such controls are well known and a specific description of the control is not necessary.
  • the control 52 cycles the source 51 on and off (preferably at approximately a l Hertz rate) with a preferred conduction cycle of percent on and I0 percent off.
  • FIG. 5A indicates current conduction from the source 51. Note that'the source 51 is in the on-mode during the period 54 and is turned off during the period 55.
  • the control 52 can be of a type which will turn off a high frequency oscillator (not illustrated) in the source 50.
  • a high frequency voltage waveform 56 having a profile indicated by the waveform 57 of FIG. 5A.
  • the source 51 be turned off for a period 55 having a time duration sufficient to turn off the SCRs 46, 47, 49 and 50 automatically by a process commonly referred to as starvation and in that sense, the controls for the individual loads are automatically turned off each time the high frequency source turns off. That is, the voltages on the SCRs are turned off for a sufficient period of time to reset each SCR automatically to the nonconducting mode.
  • the SCRs 47 and 50 could be deleted with the result being that a less than full 360 degree current source is supplied to the induction coil.
  • the SCRs 47 and 50 can also be replaced with a diode.
  • the SCRs 46 and 47 and the SCRs 49 and 50 can be replaced with a TRIAC with substantially equal results.
  • the power control 43 can be regulated in a manner to serve as a means to turn on at any time interval following the turning on of the source 51 by the control 52 thus for the time interval after the high frequency source is turned back on but before the control 43 turns on, energy flow from the source to the load is impeded.
  • the source 51 supplies the input signal for the time duration 54, however, because the gating control 43 is regulated not to turn on during the period 58, and only to initiate to the coil A approximately one-half of the power av ail- It can be seen from the foregoing that the SCRs 46,
  • I 47, 49 and 50 can be used as the control elements for thehigh frequency signal without theattendant power losses normally associated with the application of such SCRs in the range of Kilohertz.
  • economically priced SCRs can be used as the variable control component because operation in the l Hertz frequency range only is required.
  • capacitors X and Y can be added in series with coil A and coil B where the natural resonant frequency of the coils and the capacitor is near or at the frequency of the high frequency source 51.
  • the basic control technique is the same as for the previous art embodiments with the added advantage of independently controlling two loads from r the same source.
  • the circuit of FIG. 6 is provided having a high frequency energy source 60 for supplying energy to the induction coil A and induction coil B for the heating of the containers 61 and 62.
  • the high frequency energy source. 60 while preferably being cycled on and offat a duty cycle of 90 percent on and 10 percent off, is only turned on when it is desired to turn on the induction coil demanding the highest energy settingv and therefore being turned on first.
  • a pair of control resistors .68 and 69 being supplied current from a L source 70 passing through each resistor in parallel and through a diode 71 to ground.
  • the output'signal from sulting in noenergy transfer to the associated container the tap 72 is supplied to the negative terminal of a comparator 74 while that of tap 75 is supplied to a negative terminal of a comparator 76.
  • a ramp signal generator 77 At the positive terminals of the comparators 74 and 76 is supplied a ramp signal generator 77 with such ramp signal appearingas that shown in FIG. 7 and indicated by the. waveform 78. It can thus be seen that depending upon the setting of the tap 72, the comparator 74 will supply an output signal for firing the SCRs 64 and 65 sometime during the period 81 (FIG. 7). However, because the Zener diode 71.
  • the comparator 76 can be made to fire any time within the time period 79 to set the SCRs 66 and 67 in the conducting mode.
  • the output signals from the comparators 74 and 76 are fed to an Or gate 82 connected to the high frequency energy source 80. Any time the Or gate 82 supplies an output or up signal, the high frequency source is turned on.
  • the energy source will remain off. Also, as in the previous embodiment the energy source is always turned off a percentage of the time as indicated by the time duration in FIG. 7. During this time duration the SCRs 64, 65, 66 and 67 if turned on previously, will be turnedoff or set in the non-conducting mode by the process known as starvationexplained previously.
  • the'energy level can be regulated to the coils A and B by manipulation of the rheostats 68 and 69 to set the level of energy supplied to the respective induction coil.
  • the source will not be turned on during each duty cycle until the power setting of the induction coil set to the highest power setting is reached.
  • the high frequency source only supplies output power when needed and all attendant losses normally occurring during operation of the source 60 even though no energy is being supplied to the induction coil such as those losses resulting from internal resistance or other attendant losses with the control components within the source are eliminated.
  • the load A energy level is controlled by an SCR 91 which receives a gating signal from the gating control A.
  • a diode 92 is provided for reverse conduction.
  • an SCR 94 controlled by a gating control B and regulates the energy level to the load B.
  • a diode 93 is provided for reverse conduction around the SCR 94.
  • the gating control 88 is regulated to turn on the SCRs86 and 87m a high frequency rate and thereafter is timed to turn off the high frequency source for a period of time sufficient to shutoff the SCRs 91 and 94 bythe process of starvation.
  • the duty cycle of the source 84 is preferably 90 percent and 10 percent off at a 1 Hertz rate.
  • the energy level to load A is controlled by permitting the SCR 91 to turn on at any time during the l Hertz cycling of the source 84.
  • the SCR 94 is controlled to regu- 9 1 late the energy level supplied to the load B
  • FIG. 8 operates in the same manner as that previously described to supply high frequency energy at regulated energy levels by use of components associated with each load which need be capable of operating only at a .1 I-Iertz rate.
  • diode 92 instead of an SCR in the same relative position reduces the number of SCRs of the'circuit but increases the voltage rating of SCR 91 under some circuit conditions.
  • One SCR and one diode has theadded advantage of being able to reverse the relative positions of the diode and the SCRs and of having common cathods of the two or more regulating SCRs. With either two SCRs back to back, or one SCR and one diode, the high frequency source can be turned on at a low frequency rate with a duty cycle equal to the longer of the duty cycles of gating control A or control B. Also the SCR and diode pairs could be replaced with a TRIAC.
  • the difference of the cost of the low frequency control components compared to two SCRs running at the high frequency being required to turn off at a kHz rate is'in the order of 10 to l or more depending on the circuit configuration used. Further the switching loss in the configuration of the present patent application is much less than if each load has its own set of high frequency SCRs.
  • control A turns on while control B is still off, the operation of circuit of FIG. 8 is the same as that of FIG. 1. If control A is on, the operation is the same with the overall load current being at a higher level. There will be a small difference in the current pulse width if load B has a natural resonance somewhat different than load A.
  • the circuit shown in FIG. 8 has an advantage over the circuits of FIGS. 4 and 6 in that the load in FIG. 8 determines the resonance and supplies the commutation means of the high frequency source whereas in FIGS. 4 and 6 a much more complex high frequency source is required to generate high frequency voltages independent of the load.
  • circuit of FIG. 8 can also be modified in the same manner that the circuit of FIG. 1 was modified to obtain that of FIG. 3A, i.e., with the additions of inductors 31 and 32.
  • circuits such as FIG. 8 i.e., two or more load
  • inductors added as in FIG. 3A and if they are not much smaller than the inductance of the individual loads, then means may be necessary to control the power to the loads to account for the different power delivered to the loads when two or more loads are on at the same time.
  • control means can be changed to deliver power to one load at a time, (i.e., full load to one load in a two-load system would be power delivered to the 10 load a little less than one-half of the time. In a threeload system, full load would be power delivered for a little less than one-third of the time).
  • FIG. 9 shows a variation of FIG. 8 in that inductors 97 and 98 are added and function similar to the inductors 31 and 32 in FIG. 3A, with the load being a fourload configuration using TRlACs instead of back-toback SCRs or SCRs in antiparallel relationship with diodes.
  • the low cost TRlACs have been found to have a very low forward drop (with respect to the current frequency and magnitude).
  • the TRIAC has the lowest losses and costs of any of the low frequency switching means described.
  • the circuit of FIG. 9 is especially applicable to home cooking ranges. Thus the operation of FIG. 9 is the same as FIG. 8 but with four loads instead of two. TRIACs are used instead of back-to-back SCRs and diodes.
  • inductors 97 and 98 are for the attendant reasons .as described for FIG. 3A.
  • the basic power control method can be as described for the circuit'at FIG. 6.
  • Two of the loads can be connected between points A and B instead of points B and C to reduce the ripple current in DC source 96. It should be noted that whether the four loads are as shown in FIG. 9 or with two loads between points A and B they are still dynamically in parallel through the DC sources 96 when the TRIACs are conducting. Further, other configurations as shown in FIGS. 1B and. 1C could be used while still keeping all the loadsdynamically in parallel. In the multiload configurations the series tuned induction heating loads are tuned to resonate at approximately the same frequency when loaded with a cooking pot or other load.
  • Another advantage of the multi-load approach is that one load can be made at a much higher power level than the other three (or one load very high and one load very low) at very little (if any) increase in cost. If this was done with a standard system (i.e., four controllers for four loads) the increase in cost would be substantial.
  • the described preferred embodiments of the multiload configurations are low in cost and more efficient than known induction heating systems. They are much more efficient than standard gas or electric stoves.
  • the invention has been shown in the multi-load configuration for home cooking ranges. It is understood that the concept could be used for other multi-load applicatrons.
  • An inductive heating apparatus for supplying energy to one or more induction heating coil loads comprising:
  • a high frequency energy source suitable for heating said load by an inductive heating effect
  • on-off switching means to cycle said energy source on and off at a frequency rate substantially lower than the high frequency rate of the energy source; and interconnecting circuit means connecting said source and said load for supplying energy to the load, said interconnecting circuit means including individual switching means for impeding energy flow from the source to the load, said individual switching means being capable of impeding energy flow after each v necting circuit individual switching means initiates energy flow to the load. 4. An inductive heating apparatus as defined in claim 3 wherein said switching means of the interconnecting circuit means automatically impedes energy flow from the source to the load each time said on-off switching means turns the energy source on.
  • Aninductive heatng apparatus as defined in claim 4 wherein said on-off switching means does not turn on the source until the time the individual switching means of the interconnecting circuit means first set to turn on after the energy source is cycled off actually turns on.
  • said high frequency energy source includes a DC source, two SCRs and two inductors all in series connection.
  • An inductive heating apparatus as defined in claim 7 wherein a plurality of loads are supplied fromsaid 12 high frequency source and the loads are four cooking positions on ahome-type' cooking range.
  • a control for regulating energy flow from a high frequency energy source comprising:
  • on-off switching means operable to cycle on and off and periodically interrupt the flow of energy from the source to the loads at a frequency substantially less than the frequency of the source;
  • a switching means control for setting the individual switching means so it ceases to impede the flow of energy from the source to the associated load during the time interval between the on-off switching means turning on but before the on-off switching means again turns off thereby to enable regulation of the flow of energy from the source to each individual load.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Inverter Devices (AREA)
  • General Induction Heating (AREA)
  • Dc-Dc Converters (AREA)
  • Ac-Ac Conversion (AREA)
US503781A 1974-09-06 1974-09-06 Circuit for controlling power flow from a high frequency energy source to a plurality of high frequency loads Expired - Lifetime US3925633A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US503781A US3925633A (en) 1974-09-06 1974-09-06 Circuit for controlling power flow from a high frequency energy source to a plurality of high frequency loads
CA231,411A CA989488A (en) 1974-09-06 1975-07-14 Circuit for controlling power flow from a high frequency energy source to a plurality of high frequency loads
GB30272/75A GB1488306A (en) 1974-09-06 1975-07-18 Induction heating apparatus
NL7508813A NL7508813A (nl) 1974-09-06 1975-07-23 Induktief verwarmingscircuit.
DE2535637A DE2535637C3 (de) 1974-09-06 1975-08-09 Schaltungsanordnung für die Steuerung einer HF-lnduktionsheizung
JP10715875A JPS5539117B2 (sv) 1974-09-06 1975-09-05
FR7527319A FR2284245A1 (fr) 1974-09-06 1975-09-05 Appareil de chauffage par induction

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US503781A US3925633A (en) 1974-09-06 1974-09-06 Circuit for controlling power flow from a high frequency energy source to a plurality of high frequency loads

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US (1) US3925633A (sv)
JP (1) JPS5539117B2 (sv)
CA (1) CA989488A (sv)
DE (1) DE2535637C3 (sv)
FR (1) FR2284245A1 (sv)
GB (1) GB1488306A (sv)
NL (1) NL7508813A (sv)

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2700187A1 (de) * 1976-01-14 1977-07-28 Matsushita Electric Ind Co Ltd Induktionsheizgeraet mit einer vorrichtung zum erfassen des nulldurchgangspunkts einer hochfrequenten schwingung
US4074101A (en) * 1975-02-14 1978-02-14 Matsushita Electric Industrial Co., Ltd. Induction heating apparatus using a pair of inversely parallel connected gate-controlled switching devices
US4092510A (en) * 1975-10-22 1978-05-30 Matsushita Electric Industrial Co., Limited Multiple-load induction heating cooking apparatus with means for eliminating interference between two or more commutation circuits
US4092509A (en) * 1975-05-12 1978-05-30 Mitchell Mclaren P Induction heating appliance circuit that produces relatively high frequency signals directly from a relatively low frequency AC power input
US4112287A (en) * 1976-11-04 1978-09-05 White-Westinghouse Corporation Central oscillator for induction range using triac burner controls
US4115677A (en) * 1975-10-02 1978-09-19 Tokyo Shibaura Electric Co., Ltd. Induction heating apparatus
US4115676A (en) * 1976-02-10 1978-09-19 Tokyo Shibaura Electric Co., Ltd. Induction heating apparatus
US4129767A (en) * 1975-06-17 1978-12-12 Matsushita Electric Industrial Company, Limited Induction heating apparatus having timing means responsive to temporary removal of cooking implement
US4147910A (en) * 1976-06-04 1979-04-03 Matsushita Electric Industrial Co., Ltd. Power adjustment with variable frequency and duty-cycle control for induction heating apparatus
US4169222A (en) * 1977-07-26 1979-09-25 Rangaire Corporation Induction cook-top system and control
US4308443A (en) * 1979-05-01 1981-12-29 Rangaire Corporation Induction cook-top with improved touch control
US4320273A (en) * 1974-05-17 1982-03-16 Matsushita Electric Industrial Company, Limited Apparatus for heating an electrically conductive cooking utensil by magnetic induction
US4453068A (en) * 1979-05-01 1984-06-05 Rangaire Corporation Induction cook-top system and control
NL8400254A (nl) * 1983-01-28 1984-08-16 Tokyo Shibaura Electric Co Inductieve verwarmingsinrichting.
US4564733A (en) * 1983-08-11 1986-01-14 Whirlpool Corporation Current limiting control circuit for induction range
FR2575354A1 (fr) * 1984-12-20 1986-06-27 Poumey Michel Installation utilisable pour la realisation de plaques de cuisson a chauffage par induction comportant plusieurs foyers reglables separement et un seul generateur
US4825625A (en) * 1986-12-17 1989-05-02 International Paper Company Sealing method and apparatus for high capacity aseptic form, fill, and seal machines
US4945467A (en) * 1988-02-26 1990-07-31 Black & Decker Inc. Multiple-mode voltage converter
USRE33467E (en) * 1985-01-30 1990-12-04 International Paper Company Induction sealing of paperboard
EP0561206A2 (de) * 1992-03-14 1993-09-22 E.G.O. Elektro-Geräte Blanc und Fischer GmbH & Co. KG Induktive Kochstellenbeheizung
US5272719A (en) * 1991-12-12 1993-12-21 Inductotherm Corp. Plural output power supply for induction holding and melting furnaces
WO1997000552A1 (de) * 1995-06-19 1997-01-03 Otto Junker Gmbh Frequenzumrichter zur speisung mehrerer induktiver verbraucher und verfahren zu seinem betrieb
US6078033A (en) * 1998-05-29 2000-06-20 Pillar Industries, Inc. Multi-zone induction heating system with bidirectional switching network
US6252433B1 (en) 1999-05-12 2001-06-26 Southwest Research Institute Single event upset immune comparator
US6310439B1 (en) * 1999-03-15 2001-10-30 Lutron Electronics Company, Inc. Distributed parallel semiconductor device spaced for improved thermal distribution and having reduced power dissipation
US20040212325A1 (en) * 2003-04-28 2004-10-28 Adamson Hugh P. Load control system and method
US20120312803A1 (en) * 2009-11-27 2012-12-13 Electrolux Home Products Corporation N.V. Induction hob and a method for controlling an induction hob
EP2712266A1 (en) * 2012-09-25 2014-03-26 Whirlpool Corporation A power supply device for a household appliance and an operating method thereof

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2633741A1 (de) * 1976-07-27 1978-02-02 Bosch Siemens Hausgeraete Kocheinrichtung zur induktiven beheizung eines kochgeraetes
FR2447640A1 (fr) * 1979-01-29 1980-08-22 Electricite De France Procede de modulation de puissance, notamment pour cuisiniere a induction
FR2448833A1 (fr) * 1979-02-08 1980-09-05 Orega Cifte Nouvel appareil de chauffage par induction comprenant un onduleur a thyristors
GB2108786B (en) * 1981-11-05 1985-12-11 Sanyo Electric Co Induction heating apparatus
FR2539265A1 (fr) * 1983-01-07 1984-07-13 Saphymo Stel Applic Physique M Appareil de chauffage par induction a plusieurs charges oscillantes alimentees par un meme onduleur a source de courant
JPS59152192A (ja) * 1983-02-07 1984-08-30 川崎重工業株式会社 サイロにおける貯蔵物の閉塞検知方法
JPS6049948U (ja) * 1983-09-14 1985-04-08 株式会社神戸製鋼所 サイクロンセパレ−タ用サイクロンの目詰り防止装置
JP2530812B2 (ja) * 1985-12-12 1996-09-04 富士電機株式会社 高周波誘導加熱装置
DE3712242A1 (de) * 1987-04-10 1988-10-27 Thomson Brandt Gmbh Schaltung zur stromversorgung einer induktiven kochstelle

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US3697716A (en) * 1971-11-19 1972-10-10 Gen Electric Induction cooking power converter with improved coil position
US3710062A (en) * 1971-04-06 1973-01-09 Environment One Corp Metal base cookware induction heating apparatus having improved power supply and gating control circuit using infra-red temperature sensor and improved induction heating coil arrangement
US3770928A (en) * 1971-12-27 1973-11-06 Gen Electric Reliable solid state induction cooking appliance with control logic
US3781506A (en) * 1972-07-28 1973-12-25 Gen Electric Non-contacting temperature measurement of inductively heated utensil and other objects
US3781503A (en) * 1971-11-19 1973-12-25 Gen Electric Solid state induction cooking appliances and circuits
US3786219A (en) * 1971-12-27 1974-01-15 Gen Electric Solid state induction cooking systems for ranges and surface cooking units
US3806688A (en) * 1972-04-13 1974-04-23 Westinghouse Electric Corp Induction heat cooking apparatus

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3710062A (en) * 1971-04-06 1973-01-09 Environment One Corp Metal base cookware induction heating apparatus having improved power supply and gating control circuit using infra-red temperature sensor and improved induction heating coil arrangement
US3697716A (en) * 1971-11-19 1972-10-10 Gen Electric Induction cooking power converter with improved coil position
US3781503A (en) * 1971-11-19 1973-12-25 Gen Electric Solid state induction cooking appliances and circuits
US3770928A (en) * 1971-12-27 1973-11-06 Gen Electric Reliable solid state induction cooking appliance with control logic
US3786219A (en) * 1971-12-27 1974-01-15 Gen Electric Solid state induction cooking systems for ranges and surface cooking units
US3806688A (en) * 1972-04-13 1974-04-23 Westinghouse Electric Corp Induction heat cooking apparatus
US3781506A (en) * 1972-07-28 1973-12-25 Gen Electric Non-contacting temperature measurement of inductively heated utensil and other objects

Cited By (38)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4320273A (en) * 1974-05-17 1982-03-16 Matsushita Electric Industrial Company, Limited Apparatus for heating an electrically conductive cooking utensil by magnetic induction
US4074101A (en) * 1975-02-14 1978-02-14 Matsushita Electric Industrial Co., Ltd. Induction heating apparatus using a pair of inversely parallel connected gate-controlled switching devices
US4092509A (en) * 1975-05-12 1978-05-30 Mitchell Mclaren P Induction heating appliance circuit that produces relatively high frequency signals directly from a relatively low frequency AC power input
US4129767A (en) * 1975-06-17 1978-12-12 Matsushita Electric Industrial Company, Limited Induction heating apparatus having timing means responsive to temporary removal of cooking implement
US4115677A (en) * 1975-10-02 1978-09-19 Tokyo Shibaura Electric Co., Ltd. Induction heating apparatus
US4092510A (en) * 1975-10-22 1978-05-30 Matsushita Electric Industrial Co., Limited Multiple-load induction heating cooking apparatus with means for eliminating interference between two or more commutation circuits
DE2700187A1 (de) * 1976-01-14 1977-07-28 Matsushita Electric Ind Co Ltd Induktionsheizgeraet mit einer vorrichtung zum erfassen des nulldurchgangspunkts einer hochfrequenten schwingung
US4115676A (en) * 1976-02-10 1978-09-19 Tokyo Shibaura Electric Co., Ltd. Induction heating apparatus
US4147910A (en) * 1976-06-04 1979-04-03 Matsushita Electric Industrial Co., Ltd. Power adjustment with variable frequency and duty-cycle control for induction heating apparatus
US4112287A (en) * 1976-11-04 1978-09-05 White-Westinghouse Corporation Central oscillator for induction range using triac burner controls
US4169222A (en) * 1977-07-26 1979-09-25 Rangaire Corporation Induction cook-top system and control
US4308443A (en) * 1979-05-01 1981-12-29 Rangaire Corporation Induction cook-top with improved touch control
US4453068A (en) * 1979-05-01 1984-06-05 Rangaire Corporation Induction cook-top system and control
NL8400254A (nl) * 1983-01-28 1984-08-16 Tokyo Shibaura Electric Co Inductieve verwarmingsinrichting.
US4542273A (en) * 1983-01-28 1985-09-17 Tokyo Shibaura Denki Kabushiki Kaisha Circuit for inductive heating apparatus with multiple high frequency energy sources
US4564733A (en) * 1983-08-11 1986-01-14 Whirlpool Corporation Current limiting control circuit for induction range
FR2575354A1 (fr) * 1984-12-20 1986-06-27 Poumey Michel Installation utilisable pour la realisation de plaques de cuisson a chauffage par induction comportant plusieurs foyers reglables separement et un seul generateur
EP0188980A1 (fr) * 1984-12-20 1986-07-30 CABLECO Société Anonyme Installation utilisable pour la réalisation de plaques de cuisson à chauffage par induction comportant plusieurs foyers réglables séparément et un seul générateur
USRE33467E (en) * 1985-01-30 1990-12-04 International Paper Company Induction sealing of paperboard
US4825625A (en) * 1986-12-17 1989-05-02 International Paper Company Sealing method and apparatus for high capacity aseptic form, fill, and seal machines
US4945467A (en) * 1988-02-26 1990-07-31 Black & Decker Inc. Multiple-mode voltage converter
US5272719A (en) * 1991-12-12 1993-12-21 Inductotherm Corp. Plural output power supply for induction holding and melting furnaces
EP0561206A2 (de) * 1992-03-14 1993-09-22 E.G.O. Elektro-Geräte Blanc und Fischer GmbH & Co. KG Induktive Kochstellenbeheizung
EP0561206A3 (en) * 1992-03-14 1993-10-13 E.G.O. Elektro-Geraete Blanc U. Fischer Induction cooking plate
US5488214A (en) * 1992-03-14 1996-01-30 E.G.O. Elektro-Gerate Blanc U. Fischer Inductive cooking point heating system
WO1997000552A1 (de) * 1995-06-19 1997-01-03 Otto Junker Gmbh Frequenzumrichter zur speisung mehrerer induktiver verbraucher und verfahren zu seinem betrieb
US6078033A (en) * 1998-05-29 2000-06-20 Pillar Industries, Inc. Multi-zone induction heating system with bidirectional switching network
US6310439B1 (en) * 1999-03-15 2001-10-30 Lutron Electronics Company, Inc. Distributed parallel semiconductor device spaced for improved thermal distribution and having reduced power dissipation
US6252433B1 (en) 1999-05-12 2001-06-26 Southwest Research Institute Single event upset immune comparator
US20040212325A1 (en) * 2003-04-28 2004-10-28 Adamson Hugh P. Load control system and method
WO2004098243A1 (en) * 2003-04-28 2004-11-11 Colorado Vnet Load control systems and methods
US6927546B2 (en) * 2003-04-28 2005-08-09 Colorado Vnet, Llc Load control system and method
US20050264242A1 (en) * 2003-04-28 2005-12-01 Adamson Hugh P Load control system and method
US7417384B2 (en) 2003-04-28 2008-08-26 Colorado Vnet, Llc Load control system and method
US20120312803A1 (en) * 2009-11-27 2012-12-13 Electrolux Home Products Corporation N.V. Induction hob and a method for controlling an induction hob
US9693396B2 (en) * 2009-11-27 2017-06-27 Electrolux Home Products Corporation N.V. Induction hob and a method for controlling an induction hob
EP2712266A1 (en) * 2012-09-25 2014-03-26 Whirlpool Corporation A power supply device for a household appliance and an operating method thereof
US9544948B2 (en) 2012-09-25 2017-01-10 Whirlpool Corporation Power supply device for a household appliance and an operating method thereof

Also Published As

Publication number Publication date
DE2535637C3 (de) 1979-09-27
CA989488A (en) 1976-05-18
GB1488306A (en) 1977-10-12
JPS5539117B2 (sv) 1980-10-08
JPS5152535A (sv) 1976-05-10
FR2284245B1 (sv) 1980-05-16
DE2535637B2 (de) 1979-01-25
NL7508813A (nl) 1976-03-09
FR2284245A1 (fr) 1976-04-02
DE2535637A1 (de) 1976-03-25

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