RF power supply with improved galvanic isolation

Abstract

Disclosed is an RF (radio frequency) power supply comprising: a power supply configured to convert an AC (alternating current) voltage at a power supply input to a second voltage at a power supply output; and an RF generator configured to receive the second voltage at the RF generator input and use the second voltage to generate an output RF signal at the RF generator output. According to embodiments of the present disclosure, the power supply performs the voltage conversion without providing galvanic isolation between the power supply input and the power supply output, thereby improving energy efficiency while reducing complexity and cost. Instead, the RF generator provides galvanic isolation between the RF generator input and the RF generator output, which can be sufficient to achieve galvanic isolation between the power supply input and the RF generator output for safety reasons.

Description

[Technical field]

[0001] Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 034,647, filed June 4, 2020, the entire disclosure of which is incorporated by reference.

[0002] The present disclosure relates to electronics, and more particularly, to RF (radio frequency) power sources. [Background technology]

[0003] An RF power source is a device that converts energy from a low frequency or DC (direct current) source, usually from an AC (alternating current) power grid, into RF energy. There are many possible applications. In the case of a transmitter, the RF energy can be used for communication. In the case of an RF generator, the RF energy can be used for other purposes such as heating, drying, or plasma generation.

[0004] For safety reasons, conductors or components directly connected to the AC utility mains (i.e., the wiring that is the source of electrical energy in a building) must be isolated from users or other equipment that is not designed for AC connection. Galvanic isolation refers to a high level of electrical insulation that prevents current from flowing from the AC power source to users or other equipment under extreme conditions. However, galvanic isolation can result in power inefficiencies. Summary of the Invention [Problem to be solved by the invention]

[0005] RF power supplies require galvanic isolation for safety reasons. However, RF power supplies also need to be as energy efficient as possible to reduce operational costs and environmental harm, especially when used in high power applications. It is desirable to provide an RF power supply that improves energy efficiency while still providing galvanic isolation for safety reasons. [Means for solving the problem]

[0006] Disclosed is an RF power supply comprising: a power supply configured to convert an AC voltage at a power supply input to a second voltage at a power supply output; and an RF generator configured to receive the second voltage at an RF generator input and use the second voltage to generate an output RF signal at an RF generator output. In some implementations, the second voltage is a DC voltage.

[0007] According to embodiments of the present disclosure, the power supply performs voltage conversion without galvanic isolation between the power supply input and the power supply output, which can improve energy efficiency while reducing complexity and cost. Instead, the RF generator provides galvanic isolation between the RF generator input and the RF generator output, which can be sufficient to achieve galvanic isolation between the power supply input and the RF generator output for safety reasons.

[0008] In some implementations, RF power supplies can be energy efficient while reducing complexity and cost through the use of an RF power supply architecture with a non-isolated power supply. Energy inefficiencies, complexity, and costs associated with galvanic isolation between the power supply input and the power supply output can be avoided or reduced. Although galvanic isolation between the RF generator input and the RF generator output can reduce energy efficiency, such reduction is relatively small and outweighed by the relatively large gain in energy efficiency from omitting galvanic isolation between the power supply input and the power supply output. In this way, RF power supplies can be energy efficient while providing galvanic isolation for safety reasons.

[0009] In some implementations, the RF generator includes multiple RF power amplifiers, each configured to use the second voltage to generate an individual RF signal, and a power combiner configured to combine the individual RF signals to generate an output RF signal. In this manner, a high power output can be achieved via multiple RF power amplifiers suitable for high power applications while realizing the aforementioned advantages of a non-isolated power supply.

[0010] In some implementations, the AC voltage is a three-phase AC voltage and the second voltage is a DC voltage, and the power supply has a rectifier circuit for converting the three-phase AC voltage to a DC voltage. The rectifier circuit can have, for example, a six-pulse rectifier. In this way, high energy efficiency of the power supply can be provided while realizing galvanic isolation for safety reasons via the RF generator.

[0011] Other aspects and features of the present disclosure will become apparent to those of ordinary skill in the art upon review of the following description of various embodiments of the present disclosure. The embodiments will be described with reference to the accompanying drawings. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram of an RF power supply having an isolated power supply and an RF generator. [Diagram 2] FIG. 1 is a block diagram of an RF power supply having a non-isolated power supply and an isolated RF generator. [Diagram 3] FIG. 1 is a circuit diagram of another RF power supply having a non-isolated power supply and an isolated RF generator. [Figure 4] FIG. 1 is a circuit diagram of another RF power supply having a non-isolated power supply and an isolated RF generator. [Diagram 5] FIG. 1 is a circuit diagram showing an example of an RF power amplifier in which input and output are not insulated from each other. [Figure 6] FIG. 1 is a circuit diagram showing an example of an RF power amplifier in which input and output are insulated from each other. [Figure 7] FIG. 11 is a circuit diagram of another example of an RF power amplifier in which input and output are insulated from each other. [Figure 8] FIG. 1 is a block diagram showing an example of a dielectric heating apparatus having an RF power source. [Figure 9] 1 is a flow chart illustrating an example of a method for heating and / or drying a product. [Figure 10] FIG. 1 is a block diagram showing an example of a transmitting device having an RF power source. [Figure 11] 1 is a flow chart illustrating an example of a method of wireless communication. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Although exemplary implementations of one or more embodiments of the present disclosure are provided below, it should be understood at the outset that the disclosed systems and / or methods may be implemented using any number of techniques, whether currently known or in existence. The present disclosure should not be limited to the exemplary implementations, drawings and techniques shown below, including the exemplary designs and implementations shown and described herein, but may vary within the scope of the appended claims together with their full scope of equivalents.

[0014] preface 1, a block diagram of an RF power supply 100 is shown having an isolated power supply 110 and an RF generator 120. In some implementations, as shown in the illustrated example, the RF generator 120 includes one or more RF power amplifiers 130 and a power combiner 140, and may include other components not specifically shown.

[0015] In some implementations, the RF power amplifier 130 uses a DC voltage. Since power is typically distributed by a power company that uses AC power, the isolated power supply 110 converts the AC voltage at the power supply input 151 to a DC voltage at the power supply output 152. In doing so, the isolated power supply 110 provides galvanic isolation between the power supply input 151 and the power supply output 152. This galvanic isolation is provided for safety reasons, for example, to prevent or mitigate voltage spikes at the power supply input 151 from propagating through the RF power supply 100. In some implementations, the isolated power supply 110 has three stages (not shown) with an inverter, a transformer, and a rectifier, and the galvanic isolation is provided by the transformer.

[0016] The RF generator 120 receives a DC voltage at an RF generator input 152 and uses the DC voltage to generate an output RF signal at an RF generator output 154. In some implementations, the RF generator 120 has multiple RF power amplifiers 130. In high power RF applications, the RF power amplifiers 130 are limited in terms of maximum power capability, and therefore multiple RF power amplifiers 130 can be used to generate even more power. The RF power outputs 153 of the multiple RF power amplifiers 130 can be combined to generate a single output 154 using a power combiner 140.

[0017] Galvanic isolation is the principle of separating functional parts of an electrical system to limit current flow so as not to allow a direct conductive path. There are many ways to achieve galvanic isolation between the power supply input and the power supply output. In some implementations, galvanic isolation is achieved by a transformer (not shown) so that electrical energy is transferred between the individual coils by induction rather than via a direct conductive path. However, other implementations are possible. In general, galvanic isolation can be achieved by capacitance using an electric field, induction using a magnetic field, or by optical, acoustic, or mechanical means. There are many types and forms of isolated power supplies available. However, galvanic isolation (e.g., using a transformer) tends to introduce significant energy inefficiencies in addition to increased complexity and cost. Thus, the RF power supply 100 of FIG. 1 leaves much to be desired.

[0018] As discussed above, galvanic isolation is provided between power supply output 152 and power supply input 151. Therefore, galvanic isolation is not required between RF generator input 152 and RF generator output 154. In this regard, RF power amplifier 130 and power combiner 140 forming RF generator 120 need not provide galvanic isolation or may provide only moderate isolation.

[0019] Improved RF Power Supply 2, a block diagram of an RF power supply 220 is shown having a non-isolated power supply 210 and an isolated RF generator 220. In operation, the non-isolated power supply 210 converts an AC voltage at a power supply input 251 to a second voltage at a power supply output 252. In some implementations, the second voltage is a DC voltage, although other implementations are possible where the second voltage is a low frequency voltage. The RF generator 220 receives the second voltage at the RF generator input 252 and uses the second voltage to generate an output RF signal at the RF generator output 254.

[0020] According to an embodiment of the present disclosure, non-isolated power supply 210 performs voltage conversion without galvanic isolation between power supply input 251 and power supply output 252, which can improve energy efficiency while reducing complexity and cost. Instead, RF generator 220 provides galvanic isolation between RF generator input 252 and RF generator output 254, which can be sufficient to achieve galvanic isolation between power supply input 251 and RF generator output 254 for safety reasons. It is noted that non-isolated power supply 210 may galvanically isolate its AC input terminals and DC output terminals (+ and -) from other circuits and surfaces. However, its AC input terminals and DC output terminals are not galvanically isolated from each other.

[0021] In some implementations, the RF power supply 220 can improve energy efficiency while reducing complexity and cost through the use of an RF power architecture with a non-isolated power supply 210. Energy inefficiencies, complexity, and costs associated with galvanic isolation between the power supply input 251 and the power supply output 252 can be avoided or reduced. Although galvanic isolation between the RF power supply input 252 and the RF power supply output 254 may reduce energy efficiency, such reduction is relatively small and outweighed by the relatively large gain in energy efficiency from omitting galvanic isolation between the power supply input 251 and the power supply output 252. In this manner, the RF power supply 220 of FIG. 2 can have improved energy efficiency compared to the RF power supply 100 of FIG. 1 while providing galvanic isolation for safety reasons.

[0022] It should be noted that RF energy is already suitable for transmission through a transformer. Thus, in some implementations, galvanic isolation between the RF generator input 252 and the RF generator output 254 is provided by an RF transformer (not shown), which allows for efficient transmission of RF energy, especially compared to the transmission of energy through a transformer in an isolated power supply. It should be noted that DC voltages and other low frequency voltages do not transmit well through a transformer. Thus, as described above, an isolated power supply may have three stages (i.e., an inverter, a transformer, and a rectifier), allowing the transformer to provide galvanic isolation before the AC voltage is rectified to a DC voltage.

[0023] There are many possibilities for the RF generator 220. In some implementations, as shown in the illustrated example, the RF generator 220 includes one or more RF power amplifiers 230 and a power combiner 240 that provides galvanic isolation, and may include other components not specifically shown. In some implementations, the RF generator 220 includes multiple RF power amplifiers, each configured to use a second voltage from the power supply output 252 to generate an individual RF signal at the RF power output 253, and the power combiner 240 combines the individual RF signals to generate an output RF signal at the RF generator output 254. In this manner, a high power output can be achieved via multiple RF power amplifiers 230 suitable for high power applications while realizing the advantages of a non-isolated power supply 210.

[0024] In particular, there are many possibilities for the power supply since no galvanic isolation between the power supply output and the power supply input is required. In some implementations, the AC voltage is a three-phase AC voltage and the second voltage is a DC voltage, and the power supply has a rectifier circuit for converting the three-phase AC voltage to a DC voltage. The rectifier circuit can have, for example, a six-pulse rectifier. In this way, high energy efficiency of the power supply can be achieved while realizing galvanic isolation for safety reasons via the RF generator 220. Further details of examples of the power supply device 200 are described below with reference to Figures 3 and 4.

[0025] For safety reasons, devices that are connected to AC mains power must be isolated from conductive equipment and surfaces that people may come into contact with. Additionally, the output of such a device, potentially its power source, may be isolated from the input that is connected to the AC mains. If the output is isolated from the input, then downstream equipment does not require isolation or only a moderate degree of isolation. This is called an "isolated power supply." Alternatively, a "non-isolated power supply" that is connected to AC mains power is isolated from the ground plane, but its output is not isolated from its input. When using non-isolated power supplies, downstream equipment must be isolated to a high level, with isolation required between input and output.

[0026] Galvanic isolation is provided between the RF generator input 252 and the RF generator output 254. In some implementations, the galvanic isolation is provided by the power combiner 240 being an isolated combiner (i.e., the power combiner input terminal 253 is galvanically isolated from the power combiner output terminal 254). Examples are described below with reference to FIGS. 3 and 4. In other embodiments, the galvanic isolation is provided by each of the RF power amplifiers 230 being an isolated RF power amplifier. Examples of isolated RF power amplifiers are described below with reference to FIGS. 6 and 7. In other implementations, the galvanic isolation is provided by both (i) the power combiner 240 being an isolated combiner and (ii) each of the RF power amplifiers 230 being an isolated RF power amplifier.

[0027] For implementations in which galvanic isolation between the RF generator input 252 and the RF generator output 254 is provided by the power combiner 240, which is an isolation combiner, it is not necessary for each of the RF power amplifiers 230 to provide galvanic isolation between its DC input terminal 252 and RF output terminal 253. Nonetheless, each of the RF power amplifiers 230 may have DC input terminals 252 (+ and -) and RF output terminals 253 that are galvanically isolated from other surfaces and connections, including control and monitoring connections.

[0028] The examples described herein focus on multiple RF power amplifiers 230. However, in other implementations, the RF generator 220 has a single RF power amplifier 230. In some implementations, galvanic isolation between the RF generator input 252 and the RF generator output 254 can be provided by a single RF power amplifier 230 that is an isolated RF power amplifier. For implementations that include a single isolated RF power amplifier 230, the power combiner 240 may not be necessary. Thus, the power combiner 240 may be omitted or may be non-isolated.

[0029] There are many possibilities for the RF power amplifier 230. In some implementations, the RF power amplifier 230 is a class D amplifier suitable for high power efficiency. However, other amplifiers are possible. For example, in other implementations, the one or more isolated RF power amplifiers 230 are class E or class F amplifiers. Exemplary RF power amplifiers are described below with reference to FIGS. 5-7.

[0030] RF Power Supply Example 3, there is shown a circuit diagram of another RF power supply 300 having a non-isolated power supply 310 and an isolated RF generator 320. The RF generator 320 has an RF power amplifier 330 and a power combiner 340 that combines the individual RF signals from the RF power amplifiers 330. In the illustrated example, the RF power amplifier 330 has three RF power amplifiers 331-333, although any suitable number of RF power amplifiers may be used.

[0031] There are many realizations of the power combiner 340. In some implementations, the power combiner 340 utilizes RF transformers 341-343 to combine the power of the RF power amplifiers 331-333. In a specific implementation, as shown in the illustrated example, the isolation combiner 340 has, for each of the RF power amplifiers 331-333, a corresponding RF transformer 341-343 having input terminals 353a-353c for receiving individual RF signals from the RF power amplifiers 331-333 such that the series connection of the RF transformers 341-343 combines the individual RF signals from the input terminals 353a-353c to generate an output RF signal 354. Other implementations are possible. The RF transformers 341-343 provide galvanic isolation between the RF generator inputs 352a-352b and the RF generator output 354 such that galvanic isolation between the power supply outputs 352a-352b and the power supply input 351 is not required. Note that input terminals 353a-353c of power combiner 340 should be galvanically isolated from the ground plane as well.

[0032] Galvanic isolation between RF generator inputs 352a-352b and RF generator output 354 is provided for the function of RF generator 320. Using power combiner 340 of FIG. 3 as an example, RF transformers 341-343 have inherent isolation to function properly. The isolation used to achieve isolation in this case is called "functional isolation". However, since the galvanic isolation provided by RF generator 320 is intended to protect users who may come into contact with RF power source 300, the isolation used to achieve galvanic isolation should be subject to a higher standard and is considered "protective isolation". The standard of isolation to protect users varies depending on the application and may be different grades including reinforced insulation, supplemental insulation or double insulation. However, in all these grades, the standard is higher than that used for functional isolation.

[0033] In the case of a non-isolated power supply, the insulation used for protection of the RF generator 320 should perform better than the insulation used for purely functional purposes in the case of an isolated power supply. The performance of the insulation is usually considered in terms of its dimensions in terms of creepage and clearance, and its performance during voltage tests, especially those used to evaluate solid insulation. Solid insulation is insulation that is not composed of a gas (e.g., air) or liquid. Clearance is the space between conductors that does not penetrate solids, and creepage is the distance between conductors that cross the surface of a solid insulator. In the case of clearance, if the insulation is protective (as in this disclosure), depending on the voltage and standard used, the clearance may involve an increase, for example, from 1.3 mm (for functional insulation) to 7.1 mm (for protective insulation). In the case of solid insulation, a voltage test can be performed to determine the adequacy of the protective insulation. For example, in the absence of special tests for functional insulation, a test for impulse withstand voltage of 5000 V and AC test voltage of 2900 V can be performed.

[0034] There are many possibilities for the power supply 310, particularly since galvanic isolation between the power supply output and the power supply input is not required. In some implementations, the power supply 310 includes rectifier circuits 311-316 that convert three-phase AC voltage to DC voltage. In a specific implementation, the rectifier circuits include six-pulse rectifiers 311-316, as shown in the illustrated example. In a specific implementation, the rectifier circuits 311-316 are diode rectifiers 311-316. Such implementations can have relatively low complexity and cost while having relatively high efficiency. Also, such implementations can have relatively high reliability and may be suitable for use in RF power generators for heating and drying applications. Although an isolated power supply may have three stages (i.e., an inverter, a transformer, and a rectifier) ​​as described above, the power supply 310 shown in FIG. 3 is relatively simple and does not require an inverter or a transformer.

[0035] The diode rectifiers 311-316 as shown in the illustrated embodiment are of relatively simple design and do not require a control system to turn the active devices on and off. However, other implementations are possible in which active switches such as IGBTs (insulated gate bipolar transistors) or MOSFETs (metal oxide field effect transistors) are used along with an active control system. For example, some or all of the diodes 311-316 can be replaced with thyristors or transistors with appropriate control circuitry. Also, it should be noted that while the illustrated embodiment focuses on 6-pulse bridge rectifiers 311-316, any number of bridge rectifiers can be used. For example, another implementation employs a 12-pulse bridge rectifier. The number of bridges is implementation dependent.

[0036] Although the rectifier circuits 311-316 are shown to convert a three-phase AC voltage at the power supply input 351 to a DC voltage at the power supply outputs 352a-352b, in other implementations, the rectifier circuits are provided to convert a single-phase AC voltage to a DC voltage. In such implementations, the power supply 310 may have a single-phase bridge rectifier (not shown). Also, although the rectifier circuits 311-316 are shown as full-wave rectifiers, in other implementations, a half-wave rectifier circuit (not shown) is provided to convert the AC voltage (either single-phase or three-phase) to a DC voltage. Also, other possible implementations may have PFC (power factor correction) rectifiers, including three-phase types (e.g., Wien rectifiers) and single-phase types (e.g., buck and boost topologies and topologies with and without a diode bridge). Other implementations are possible.

[0037] Referring to FIG. 4, a circuit diagram of another RF power supply 400 having a non-isolated power supply 410 and an isolated RF generator 320 is shown. The RF power supply 400 of FIG. 4 is identical to the RF power supply 300 of FIG. 3, except that filters 417-418 have been added to the power supply 410 to reduce ripple voltage at the power supply outputs 352a-352b. There are many realizations of the filters 417-418. In some implementations, as shown in the illustrated example, the filters 417-418 are LC filters 417-418 having an inductor 417 and a capacitor 418. Such an implementation may be preferred for high power radio transmitters using PSM (Pulse Step Modulation) or PDM (Pulse Duration Modulation) when the RF amplifier 330 has a PDM (Pulse Duration Modulation) modulator. See, for example, U.S. Pat. No. 2,903,518. Other implementations of the filters are possible.

[0038] As with the RF power supply 300 of FIG. 3, the number of RF power amplifiers 330 is implementation specific. In a specific implementation, there are eight RF power amplifiers 331-333 (only three are shown). However, other implementations are possible. In some implementations, the RF power supply 400 has control circuitry (as shown) that individually enables or disables each of the RF power amplifiers 331-333. This can be done to adjust the power output depending on the application. In some implementations, the control circuitry provides a modulation technique that turns on and off the RF power amplifiers 331-333 with power combiners 340 having different turns ratios to perform the modulation. For such implementations, the multiple RF power amplifiers 330 can have ten or more RF power amplifiers 331-333. However, other implementations are possible.

[0039] In another implementation, RF power supply 400 has a two-stage amplifier (not shown) with an additional step-down topology type DC-DC converter (i.e., a modulator) before RF amplifier 330. To achieve even greater power output, multiple amplifier stages can be utilized.

[0040] RF Power Amplifier Example Referring to FIG. 5, a circuit diagram of an exemplary RF power amplifier 500 without isolation between input and output is shown. In the illustrated example, the RF power amplifier 500 is a full-bridge class D amplifier, which has power transistors 501-504 (e.g., MOSFETs) that operate as electronic switches rather than as linear gain devices as in other amplifiers. The power transistors 501-504 are controlled by control circuits 511-514 to generate an RF output 353. Isolation circuits are used to provide protective galvanic isolation between the gate connections of the power transistors 501-504 and the control circuitry that operates at ground potential. Note that the power terminals (DC inputs 352a-352b and RF output 553) are fully isolated from the ground and control circuitry connections. However, the RF power amplifier 500 does not have galvanic isolation between the DC inputs 352a-352b and the RF output 553.

[0041] The RF power amplifier 500 shown in Figure 5 has galvanic isolation between the control circuits 511-514 and all four of the power transistors 501-504. This galvanic isolation is provided so that the power amplifier 500 can be used in combination with a non-isolated power supply in which the RF AC input and DC output terminals are not galvanically isolated from one another. Note that in an isolated power supply, the DC-potential of the power supply is typically ground potential and a non-isolated drive circuit can be used to control the gate terminal of a transistor whose source terminal (in the case of a MOSFET) is connected to a grounded power supply connection (e.g., DC-connection 352b in Figure 5).

[0042] Galvanic isolation between the control circuits 511-514 and all four of the power transistors 501-504 is provided for the function of the RF power amplifier 500. By using the RF power amplifier 500 of FIG. 5 as an example, the two transistors 501-502 connected to the DC+ terminal 352a are inherently isolated for proper functioning. The reason is that the source terminals of these RF power transistors 501-502 are at the potential of the RF output 353 and not at the ground potential normally used by the control system. The isolation used to provide the isolation used in this case is called "functional isolation". However, since the isolation used is intended for the protection of users who may come into contact with the RF power source, the isolation needs to be upgraded to a higher standard called "protective isolation". The standard of isolation for the protection of users varies depending on the application and there are various grades including reinforced isolation, supplementary isolation or double isolation. However, in all these grades, the standard is higher than that used for functional isolation, as described above for the RF generator 320 of FIG. 3 and FIG. 4.

[0043] There are many ways to implement galvanic isolation between the DC inputs 352a-b and the RF output 353. In some implementations, galvanic isolation between the DC inputs 352a-b and the RF output 353 is implemented via an internal output transformer. An example of this is shown in FIG. 6, which is a circuit diagram of an exemplary RF power amplifier 600 with input-output isolation. The internal output transformer 631 provides isolation between a non-isolated power source and the final output. Thus, the RF power amplifier 600 may be used without the use of an isolated coupler because of the built-in isolation. Similar to the RF power amplifier 500 of FIG. 5, the RF power amplifier 600 of FIG. 6 has isolated driver circuits 511-514 that provide isolation between the RF power amplifier 600 and the control circuitry that is typically at ground potential.

[0044] Referring to FIG. 7, a circuit diagram of another example RF power amplifier 700 with input-output isolation is shown. In the illustrated example, the RF power amplifier 700 is a class E amplifier having a power transistor 701 (e.g., a MOSFET) controlled by a control circuit 711 to drive tuned reactive networks 721-724 and generate an RF output 353. The tuned reactive networks 721-724 can have any suitable combination of inductors 721-722 and / or capacitors 723-724. Typically, a class E amplifier does not use an isolated connection to the gate terminal because the MOSFET source connection is at ground potential. An isolation circuit is used to provide protective galvanic isolation between the gate connection of the power transistor 701 and the control circuit 711 operating at ground potential, similar to that described above for the RF power amplifier 500 of FIG. 5. Note that the power terminals (DC inputs 352a-352b and RF output 535) are fully isolated from ground and the control circuit connections. Typically, the DC-connection 352b is at ground potential. Additionally, the RF power amplifier 700 has galvanic isolation between the DC inputs 352a-352b and the RF output 353 via an internal output transformer 731. Thus, the RF power amplifier 700 may be used without the use of an isolation coupler since the isolation is built in.

[0045] Application Examples There are many possible applications of the RF power supply described herein. As a first example, the RF power supply can be used to heat and / or dry a product, as will be described in more detail below with reference to Figures 8 and 9. As a second example, the RF power supply can be used for wireless communication, as will be described in more detail below with reference to Figures 10 and 11. However, it will be appreciated that other applications, such as, for example, the generation of plasma, are also possible. The RF power supplies described herein can be applied in many different applications and in many different industries.

[0046] 8, a block diagram of an exemplary dielectric heating apparatus 800 having an RF power supply 810 is shown. The RF power supply 810 is configured to generate an output RF signal as described herein. The dielectric heating apparatus 800 has a pair of electrodes 821-822 for converting the output RF signal from a voltage and current signal to an alternating electric field 830. In operation, the alternating electric field 830 is applied to a product (not shown) to heat and / or dry the product. In some implementations, as shown in the illustrated example, the product moves between the electrodes 821-822 via a conveyor belt 840, thereby exposing the product to the alternating electric field 830 as the product moves between the electrodes 821-822. However, other means for exposing the product to the alternating electric field 830 are possible.

[0047] The dielectric heating device 800 can be used in industrial settings. For example, the dielectric heating device 800 can be used for process heating in manufacturing, especially bulk goods where product uniformity is important. As a specific example, the dielectric heating device 800 can be used for drying wood products. As another example, the dielectric heating device can be used to heat food products. Other applications of the dielectric heating device 800 are possible and are within the scope of this disclosure.

[0048] Referring to FIG. 9, a flow chart of an exemplary method for heating and / or drying a product is shown. The method may be performed by a dielectric heating device, such as the dielectric heating device 800 shown in FIG. 8 or any other suitably configured dielectric heating device. In step 9-1, the dielectric heating device generates an output RF signal. This may be done by using an RF power supply as described herein. In step 9-2, the dielectric heating device converts the output RF signal from a voltage and current signal to an AC electric field. This may be done, for example, by using electrodes. Finally, in step 9-3, the dielectric heating device applies an AC electric field to the product to heat and / or dry the product.

[0049] Referring to FIG. 10, a block diagram of an exemplary transmitter device 1000 having an RF power source 1010 is shown. The RF power source 1010 is configured to generate an output RF signal 1054 as described herein. The transmitter device 1000 has an antenna 1020 coupled to the RF power source 1010 to convert the output RF signal 1054 from a voltage and current signal to an electromagnetic wave for transmission over a wireless channel. In some implementations, as shown in the illustrated example, the antenna 1020 is coupled to the RF power source 1010 via a transmission line 1030. Some degree of reflected signal 1055 is possible. In most relevant high power implementations, the antenna 1020 and the RF power source 1010 are physically separated, and therefore the transmission line 1030 is utilized to connect the antenna 1020 to the RF power source 1010. However, in other implementations, the transmission line 1030 is not present.

[0050] Referring to FIG. 11, a flow chart of an exemplary method of wireless communication is shown. The method may be performed by a transmitting device, such as the transmitting device 1000 shown in FIG. 10 or any other suitably configured transmitting device. In step 11-1, the transmitting device generates an output RF signal. This may be done by using an RF power source as described herein. In step 11-2, the transmitting device converts the output RF signal from a voltage and current signal into an electromagnetic wave for transmission over a wireless channel. This may be done by using an antenna, for example. In some implementations, the RF power source is connected to a transmission line terminated with an antenna to generate the electromagnetic wave.

[0051] Numerous modifications and variations of the present disclosure are possible in light of the above teachings, and it is therefore understood that within the scope of the appended claims the present disclosure may be practiced otherwise than as specifically described herein. The inventions disclosed herein include the following: [Aspect 1] An RF (radio frequency) power source, a power supply configured to convert an AC (alternating current) voltage at the power supply input to a second voltage at the power supply output without galvanic isolation between the power supply input and the power supply output; an RF generator configured to receive the second voltage at an RF generator input and to use the second voltage to generate an output RF signal at an RF generator output, the RF generator providing galvanic isolation between the RF generator input and the RF generator output; wherein the RF generator comprises a plurality of RF power amplifiers each configured to use the second voltage to generate an individual RF signal, and a power combiner configured to combine the individual RF signals to generate the output RF signal. [Aspect 2] 2. The RF power source of claim 1, wherein the AC voltage comprises a three-phase AC voltage, the second voltage comprises a DC (direct current) voltage, and the power supply device comprises a rectifier circuit that converts the three-phase AC voltage to the DC voltage. [Aspect 3] 3. The RF power source of embodiment 2, wherein the rectifier circuit comprises a six-pulse rectifier. [Aspect 4] 4. The RF power supply of any one of claims 2 to 3, wherein the rectifier circuit comprises a diode rectifier. [Aspect 5] 5. The RF power supply of any one of aspects 1 to 4, wherein the power supply further comprises a filter configured to reduce ripple voltage. [Aspect 6] 6. The RF power supply of any one of aspects 1 to 5, wherein galvanic isolation between the RF generator input and the RF generator output is provided by a power combiner comprising an isolation coupler. [Aspect 7] 7. The RF power supply of embodiment 6, wherein the isolation combiner comprises a plurality of RF transformers that combine power of the RF power amplifiers while providing galvanic isolation between the RF generator input and the RF generator output. [Aspect 8] 8. The RF power source of claim 7, wherein the isolated combiner comprises, for each of the RF power amplifiers, a corresponding RF transformer of the plurality of RF transformers for receiving the individual RF signals from the RF power amplifier, such that a series connection of the plurality of RF transformers combines the individual RF signals to generate the output RF signal. [Aspect 9] 9. The RF power supply according to any one of aspects 6 to 8, wherein the isolation coupler provides protective insulation that exceeds functional insulation. [Aspect 10] 6. The RF power supply of any one of aspects 1-5, wherein galvanic isolation between the RF generator input and the RF generator output is provided by the RF power amplifiers, each of which comprises an isolated RF power amplifier. [Aspect 11] 11. The RF power supply of embodiment 10, wherein the isolated RF power amplifier comprises a full-bridge class D amplifier having an internal output transformer for providing the galvanic isolation. [Aspect 12] 11. The RF power supply of embodiment 10, wherein the isolated RF power amplifier comprises a class E amplifier having an internal output transformer for providing the galvanic isolation. [Aspect 13] 13. The RF power supply according to any one of aspects 10 to 12, wherein each of the isolated RF power amplifiers provides protective insulation that exceeds functional insulation. [Aspect 14] 6. The RF power supply of any one of aspects 1-5, wherein galvanic isolation between the RF generator input and the RF generator output is provided by both (i) the power combiner comprising an isolated coupler, and (ii) each of the RF power amplifiers comprising an isolated RF power amplifier. [Aspect 15] 15. The RF power supply according to any one of aspects 1 to 14, wherein the plurality of RF power amplifiers includes eight RF power amplifiers. [Aspect 16] 16. The RF power supply according to any one of aspects 1 to 15, further comprising a control circuit that individually enables or disables each of the RF power amplifiers. [Aspect 17] An RF (radio frequency) power source, a power supply having a rectifier circuit configured to convert a three-phase AC (alternating current) voltage at the power supply input to a DC (direct current) voltage at the power supply output without galvanic isolation between the power supply input and the power supply output; an RF generator configured to receive the DC voltage at an RF generator input and to use the DC voltage to generate an output RF signal at an RF generator output, the RF generator providing galvanic isolation between the RF generator input and the RF generator output; 1. An RF power source comprising: [Aspect 18] 18. The RF power source of embodiment 17, wherein the rectifier circuit comprises a six-pulse rectifier. [Aspect 19] 19. The RF power source of claim 17 or 18, wherein the rectifier circuit comprises a diode rectifier. [Aspect 20] 20. The RF power source of any one of aspects 17 to 19, wherein the power supply further comprises a filter configured to reduce ripple voltage. [Aspect 21] A dielectric heating apparatus comprising: an RF power supply according to any one of aspects 1 to 20 for generating the output RF signal; and a pair of electrodes coupled to the RF power supply for converting the output RF signal from a voltage and current signal to an AC electric field. [Aspect 22] 1. A method for heating and / or drying a product, comprising the steps of: generating the output RF signal using an RF power supply according to any one of aspects 1 to 20; converting the output RF signal from a voltage and current signal to an AC electric field; applying said alternating electric field to said product to heat and / or dry said product; A method for providing the above. [Aspect 23] 21. A transmitting apparatus comprising: an RF power supply according to any one of aspects 1 to 20 for generating an output RF signal; and an antenna coupled to the RF power supply for converting the output RF signal from a voltage and current signal to an electromagnetic wave for transmission over a wireless channel. [Aspect 24] 1. A method of wireless communication, comprising: generating the output RF signal using an RF power supply according to any one of aspects 1 to 20; converting the output RF signal from a voltage and current signal to an electromagnetic wave for transmission over a wireless channel; A method for providing the above.

Claims

1. An RF (radio frequency) power source, a power supply configured to convert an AC (alternating current) voltage at the power supply input to a second voltage at the power supply output without galvanic isolation between the power supply input and the power supply output; an RF generator configured to receive the second voltage at an RF generator input and to use the second voltage to generate an output RF signal at an RF generator output, the RF generator providing galvanic isolation between the RF generator input and the RF generator output; wherein the RF generator comprises a plurality of RF power amplifiers each configured to use the second voltage to generate an individual RF signal, and a power combiner configured to combine the individual RF signals to generate the output RF signal.

2. 2. The RF power source of claim 1, wherein the AC voltage comprises a three-phase AC voltage, the second voltage comprises a DC (direct current) voltage, and the power supply comprises a rectifier circuit that converts the three-phase AC voltage to the DC voltage.

3. 3. The RF power supply of claim 2, wherein the rectifier circuit comprises a six-pulse rectifier.

4. 4. An RF power supply as claimed in claim 2 or 3, wherein the rectifier circuit comprises a diode rectifier.

5. The RF power supply of any one of claims 1 to 4, wherein the power supply further comprises a filter configured to reduce ripple voltage.

6. An RF power supply according to any one of claims 1 to 5, wherein galvanic isolation between the RF generator input and the RF generator output is provided by a power combiner comprising an isolation coupler.

7. 7. The RF power supply of claim 6, wherein the isolation combiner comprises a plurality of RF transformers that combine the power of the RF power amplifiers while providing galvanic isolation between the RF generator input and the RF generator output.

8. 8. The RF power supply of claim 7, wherein the isolation combiner comprises, for each of the RF power amplifiers, a corresponding RF transformer of the plurality of RF transformers for receiving the individual RF signals from the RF power amplifier, such that a series connection of the plurality of RF transformers combines the individual RF signals to generate the output RF signal.

9. The RF power supply of any one of claims 6 to 8, wherein the isolation coupler provides protective isolation that exceeds functional isolation.

10. An RF power supply according to any one of claims 1 to 5, wherein galvanic isolation between the RF generator input and the RF generator output is provided by the RF power amplifiers, each comprising an isolated RF power amplifier.

11. 11. The RF power supply of claim 10, wherein the isolated RF power amplifier comprises a full-bridge class D amplifier having an internal output transformer to provide the galvanic isolation.

12. 11. The RF power supply of claim 10, wherein the isolated RF power amplifier comprises a class E amplifier having an internal output transformer to provide the galvanic isolation.

13. The RF power supply of any one of claims 10 to 12, wherein each of the isolated RF power amplifiers provides protective isolation that exceeds functional isolation.

14. 6. The RF power supply of claim 1, wherein galvanic isolation between the RF generator input and the RF generator output is provided by both (i) the power combiner comprising an isolated coupler, and (ii) each of the RF power amplifiers comprising an isolated RF power amplifier.

15. 15. An RF power source according to any preceding claim, wherein the plurality of RF power amplifiers comprises eight RF power amplifiers.

16. 16. An RF power supply according to any preceding claim, comprising control circuitry for individually enabling or disabling each of the RF power amplifiers.

17. A dielectric heating apparatus comprising: an RF power supply according to any one of claims 1 to 16 for generating the output RF signal; and a pair of electrodes coupled to the RF power supply for converting the output RF signal from a voltage and current signal to an alternating electric field.

18. 1. A method for heating and / or drying a product, comprising the steps of: Generating the output RF signal using an RF power supply according to any one of claims 1 to 16; converting the output RF signal from a voltage and current signal to an AC electric field; applying said alternating electric field to said product to heat and / or dry said product; A method for providing the above.

19. 17. A transmitter comprising an RF power supply according to any one of claims 1 to 16 for generating the output RF signal, and an antenna coupled to the RF power supply for converting the output RF signal from a voltage and current signal to an electromagnetic wave for transmission over a wireless channel.

20. 1. A method of wireless communication, comprising: Generating the output RF signal using an RF power supply according to any one of claims 1 to 16; converting the output RF signal from a voltage and current signal to an electromagnetic wave for transmission over a wireless channel; A method for providing the above.

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