This application is a National Stage of PCT/GB2013/052026, filed on Jul. 29,2013, which claims priority to GB 1213402.9, filed Jul. 27, 2012.
This invention relates to high frequency energy generator systems.
Microwaves may be used in industrial processing applications for heating or drying applications or to modify materials under treatment in some other way. In one application of microwave processing, for example, microwaves are used to exfoliate vermiculite by interacting with water found between layers of the material to cause expansion of the material.
Magnetrons are microwave generators suitable for industrial processing purposes. In one type of processing system, a conveyor carries material along a line and several processing stages take place at different locations. Magnetrons may be set up at appropriate places in a processing line so that they are close to where the microwave processing is required. However, this may not always be convenient or feasible because of the spatial requirements for each magnetron and its ancillary components. One solution is to locate magnetrons remotely from the line and construct waveguides to deliver the output of a magnetron to where it is required.
According to a first aspect of the invention, a high frequency energy generator system comprises: a plurality of high frequency energy generator heads, each head including a respective magnetron; a common drive unit for producing power for the plurality of magnetrons; and a connector arrangement simultaneously connecting each of the plurality of heads to the common drive unit for supplying power to the magnetrons, at least one of the heads being located remote from the common drive unit.
Power supplied to the generator system, for example, from a grid supply or a power generator, is conditioned by the common drive unit to make it suitable for driving the magnetrons. As each of the plurality of heads is simultaneously connected to the common drive unit, it enables all of the magnetrons to be operated simultaneously if required. In one embodiment, the magnetrons are operable independently of one another, such that all or some may be adjusted to change output power without affecting the operational states of others.
Use of a common drive unit to supply power for a plurality of magnetrons may enable ancillary components to be combined at the common drive unit, for example, such that several magnetrons may be supplied by fewer components than would be required for separately provisioned magnetrons. Alternatively, or in addition, the same number of components may be used but more efficiently provided by being co-located at the common drive unit. Furthermore, the high frequency energy generator head including the magnetron may be more compact compared to previous configurations which deployed stand alone magnetrons each having its own power supply and other ancillary components. Thus the spatial requirements for the magnetrons may be reduced, such that, for industrial processing use, for example, it can allow greater flexibility in positioning closer to where microwaves are required, reducing or eliminating the need for long and/or complex waveguide structures. Also, the connector arrangement may be relatively flexible, for example, comprising co-axial cabling, and thus may be readily re-positioned if a head is to be moved, which can be more difficult to achieve if significant waveguide structures have to be taken into account.
In one embodiment, heads having an output at 100 kW operate at several MHz but other power outputs and frequencies are possible. For example, systems are envisaged that may operate in the order of hundreds of MHz. In one embodiment, each magnetron in the generator system has the same operating frequency. In another embodiment, one or more of the magnetrons operate at respective different frequencies.
In an embodiment, each of the high frequency energy generator heads has a single magnetron, but there may be some arrangements in which one or more of the heads includes two or more magnetrons.
In one embodiment, at least a majority of the heads are located remote from the common drive unit. In another embodiment, only one head is remotely located and one or more of the other heads is co-located with the common drive unit. In one embodiment, all of the heads are located remotely from the common drive unit.
In an embodiment, the heads are positioned to supply high frequency energy to materials in an industrial processing arrangement. The industrial processing arrangement may involve a continuous process, for example, and the heads are positioned along a path followed by material processed in the continuous industrial processing arrangement. In another arrangement, the industrial processing arrangement involves batch processing. However, the system may be used in applications other than industrial processing where generation of microwaves is required, for example, but not limited to: soil remediation, agriculture, medical or military applications.
In an embodiment, at least one head is positioned at a different height than another head. A system in accordance with the invention may permit the head to be more compact and lighter in weight than previous magnetron apparatus having magnetron and ancillary components combined together. Thus it provides more options for locating the heads and gives greater flexibility in designing material processing lines, for example, in which the system is deployed.
In an embodiment, at least one head is moveable during generation of high frequency energy. It would be possible to scan a fixed target. The relative positions of the head and body do not need to be at fixed angles so heads can easily be mounted in any orientation. The connector arrangement may be, for example, sufficiently flexible to permit movement or some other mechanism may be used.
The connector arrangement may in one embodiment comprise respective different connectors for at least some of the heads. Thus, in one system, each head is connected via a dedicated connector, such as a coaxial cable, to the common drive unit. In another system, some or all of the heads are connected via a connector arrangement having a common portion and a divided portion having a plurality of sections, the sections connecting to respective different heads.
The connector arrangement comprises means to deliver power and may also include means to deliver at least one of: cooling fluid; magnetron control signalling; magnetron heater supply; safety control signalling; and electromagnet power supply. The connector arrangement may include lines for different deliverables bundled together. In another embodiment, some or all of them are combined into a single sheath, for example, providing ease of handling when deploying the system.
In one embodiment, each head includes a magnetron, an input adapted to receive power from the common drive unit, and output for high frequency energy generated by the magnetron and at least one of: an electromagnet; a control and monitoring module; a low voltage power supply; and local cooling apparatus. Each head in a system may be nominally identical, but in another system, one head may have a different internal layout or include different components to another. For example, one head may have individually provided coolant whereas other heads are arranged to receive coolant via a common route.
In one embodiment, the common drive unit includes: power supply means having a plurality of outputs, the outputs being connected to inputs of step-up transformer means and outputs of the step-up transformer means being connected to the connector arrangement.
The power supply means may comprise an input drive module connected via a common DC link to a plurality of output drive modules, and outputs of the output drive modules being said plurality of outputs of the step-up transformer means. However, other arrangements are possible. For example, in another embodiment, an active front end is included instead of the input drive module.
In one embodiment, at least one of the output drive modules is connected to inputs of a plurality of step-up transformers.
In one embodiment, the common drive unit includes: first switched mode power supply (SMPS) means, and a plurality of second SMPS means connected in series to the first SMPS means by DC bus means with capacitor means connected between outputs of the first SMPS means and between inputs of respective second SMPS means, the outputs of the plurality of second SMPS means being connected to inputs of respective step-up transformer means, wherein the plurality of second SMPS means is arranged to feed respective step-up transformer means and to operate with a variable duty cycle and/or variable frequency to provide average power control for application to respective magnetrons.
In one embodiment, the common drive unit includes power supply means, a plurality of step-up transformers and at least one of: magnetron heater supply means; common cooling apparatus for supplying coolant to the plurality of heads; and a control module for controlling operation of the magnetrons.
In one embodiment, means are included for independently controlling operation of the magnetrons. For example, where six heads are included, each having one magnetron, the magnetrons may be operated as pairs. Also, individual magnetrons may be isolated from the system for maintenance or because they are not required for a time period.
Components of the common drive unit may be co-located and, in one embodiment, are contained within a common housing although this is not essential. In another embodiment, some of the components of the common drive unit are positioned at a first location and other components of the common drive unit are positioned at a second location, the second location being between the first location and one or more of the plurality of heads. In an embodiment, the components of the common drive unit may be housed in first and second housings located at the first and second locations respectively. In one embodiment, the power supply means may comprise an input drive module connected via a common DC link to a plurality of output drive modules, and the input drive module is housed in a first housing and the plurality of output drive modules in a second housing, with the common DC link extensive between the first and second housings. In another embodiment, an active front end is used instead of the input drive module.
According to a second aspect of the invention, a high frequency delivery head comprises: a magnetron; an input adapted for receiving power for the magnetron via a connector from a common drive unit for producing power for a plurality of magnetrons; an output for high frequency energy generated by the magnetron and at least one of: an electromagnet; a control and motoring module; a low voltage power supply; and local cooling apparatus.
Some embodiments of the present invention will now be described by of example only, and with reference to the accompanying drawings, in which:
With reference to
Each head 3 to 8 is located remote from the common drive unit 2 and, in this embodiment, the connectors 10 to 15 have a maximum length of 10 m and are flexible to facilitate positioning of the heads.
A three phase electrical signal of 690V is applied to an input 16 of the common drive unit 2. The input is filtered at 17 to suppress harmonics and then applied to an input drive module 18 which has three single channels. The output of the primary drive module 18 is applied via a dc link 19 to two output drive modules 20 and 21, providing an input to them at 1000V. The output drive modules 20 and 21 have three phase switched outputs which are applied to high voltage step-up transformer units 22 to 27. At each transformer unit 22 to 27, the input is amplified resulting in a switched high voltage output of 20 kV. This is supplied to the heads 3 to 8 to power the magnetrons so that each head delivers an output at 100 kW, giving 600 kW in total for this system.
The output of the filter 17 is also applied to a 690V to 400V transformer 28, also included in the common drive unit 2, to obtain a supply for internal equipment included in the heads 3 to 8 such as a heater supply and electromagnet supply. The output of this transformer 28 is supplied to the heads 3 to 8 via a separate route 29 from the connector arrangement 9 in this embodiment, the output power of the transformer 28 being approximately 25 kW.
Cooling is required at the heads 3 to 8 and this is applied via a common cooling system 30, which may use air or liquid as the coolant as appropriate. Parts of the cooling system are included in the common drive unit 2 and may also provide cooling thereto.
The common drive unit 2 also houses a system control and monitoring sub-system 31 which controls operation of the magnetrons via a control line 32. The control of the magnetrons may be dependent or independent on the process for which the microwaves are required, or different modes may be used at different times. Also, the control system may be used to switch down individual magnetrons for routine or emergency maintenance, for example. This may be particularly important when it would be financially and technically undesirable to close an entire process line down. Safety controls are also handled in sub-system 31, receiving inputs from the heads 3 to 8 indicating status such as arcing or leakage of high frequency radiation.
Although the system of
With reference to
The high frequency energy generator heads in this embodiment are nominally identical. Some components included in the head 38 are schematically shown and include a magnetron 39, electromagnet 40 and launch waveguide 41 for receiving the output of the magnetron 40 and applying it via a circulator 42 to an output port 43.
Components of the system of
With reference to
With reference to
The high frequency energy generator heads in the
The common drive unit may be implemented in a number of different ways. One approach is as described in our patent application WO 2008/149133. Switched mode power supplies (SMPS) linked in series by a DC bus are used. The primary SMPS connects to a prime power input and maintains a high power factor with low harmonic content while setting the magnetron operating voltage and peak current levels. The secondary SMPSs feed step up transformers, single or 3-phase, and operate with a variable duty cycle and/or variable frequency to provide average power control. Rectified output is fed directly to the magnetrons without filtering.
With reference to
A C1 capacitor 56 is connected across the DC output of SMPS 150 and the DC input of SMPS254.
The second switched mode power supply (SMPS2) 54 has three outputs P1, P2 and P3 and operates as a DC to 3-Phase AC converter with an output to a Ti transformer 58, corresponding to one of the transformers 22 to 27 of
A current through the magnetron 62 is monitored by an R1 resistor 66 between a positive voltage output of the rectifier 60 and an anode of the magnetron 62. An operating voltage of the magnetron 62 can be set to a predetermined value by setting a current through a solenoid 68 which is controlled by a solenoid supply 70 to set a magnetic field which is applied to the magnetron 62. Over a usual range of operation the magnetron voltage is virtually directly proportional to the solenoid current.
A main control board 72 has a signal input from the R1 resistor 66 via a control line c4 and an output for a control signal for SMPS150 on a control line cl and for the solenoid supply 70 on a control line c5. All these functions can be controlled by an amplitude control module 74 with an input to the main control board 72, that permits the required magnetron voltage and current to be set with a single control, so that the magnetron peak voltage and current and thus the RF power peak value is set thereby for the system.
SMPS254 is designed to produce a transformer-compatible 3-phase nominally rectangular pulse drive waveform that can be used to vary the average magnetron current by pulse width modulation techniques.
Magnetron anode current is monitored by R1 resistor 66 and a signal is input via control line c4 to the main control board 72 and an output signal is output to SMPS254 via control line c2. Varying the duty cycle of the SMPS254 varies the pulse duty output, and thus the average power from SMPS254. A duty cycle control 76 input to the main control board 72 permits a required duty cycle to be set. Magnetrons, as distinct from at least some other generators of microwave power, require the heater voltage to be reduced as the average power increases. The main control board 72 also performs this function by outputting a control signal on control line c3 to control the heater supply 78 having an output to a heater T2 transformer 80 electrically coupled via the connector arrangement to the heater of the magnetron 62.
In another arrangement, a regenerative active front end AFE may be used to provide the function of the SMPS1. This allows the DC link voltage to be set, for example, as shown at amplitude control 74 on
For a high-power system a typical set of values for an application are C1 voltage 800V for a magnetron operating at 20 kV at 6 A peak for 65 to 100 kW of peak RF output. The magnetron frequency is centred on 896 MHz in one example but other frequencies may be used instead, for example, to take into account different national standards. The duty cycle is 50% for 50 kW average output power. Operating frequency for SMPS150 and SMPS254 is 4,000 pps. In one system, each of the magnetrons operates at substantially the same frequency. In another system, one or more magnetrons operate at respective different frequencies.
With reference to
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
Number | Date | Country | Kind |
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1213402.9 | Jul 2012 | GB | national |
Filing Document | Filing Date | Country | Kind |
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PCT/GB2013/052026 | 7/29/2013 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2014/016623 | 1/30/2014 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
3601448 | Stone | Aug 1971 | A |
4256944 | Brandon | Mar 1981 | A |
4904835 | Koch et al. | Feb 1990 | A |
5227598 | Woodmansee et al. | Jul 1993 | A |
5481092 | Westmeyer | Jan 1996 | A |
5575106 | Martin et al. | Nov 1996 | A |
5980962 | Bracken | Nov 1999 | A |
20030224082 | Akopyan | Dec 2003 | A1 |
20070102279 | Novak | May 2007 | A1 |
20090173667 | Varma | Jul 2009 | A1 |
20120061384 | Kasai et al. | Mar 2012 | A1 |
20130075390 | Ashida | Mar 2013 | A1 |
Number | Date | Country |
---|---|---|
2487990 | Aug 2012 | EP |
1305146 | Jan 1973 | GB |
2420542 | May 2006 | GB |
H05343178 | Dec 1993 | JP |
H09049635 | Aug 1995 | JP |
H113775 | Jan 1999 | JP |
2003187957 | Jul 2003 | JP |
WO-8800425 | Jan 1988 | WO |
WO-2008149133 | Dec 2008 | WO |
Entry |
---|
GB Search Report of Application No. GB 1213402.9 dated Jun. 19, 2013. |
GB Search Report of Application No. GB1313493.7 dated Jan. 29, 2014. |
International Search Report of PCT/GB2013/052026 dated Aug. 20, 2014. |
Written Opinion of the ISA of PCTGB2013/052026 dated Jan. 7, 2014. |
International Preliminary Report on Patentability in corresponding International Application No. PCT/GB2013/052026, issuance of report on Jan. 27, 2015, 13 pages. |
International Search Report in corresponding International Application No. PCT/GB2013/052026, dated Sep. 4, 2014, 6 pages. |
Number | Date | Country | |
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20150257209 A1 | Sep 2015 | US |