Generator and method of use

Abstract

Various embodiments of the present disclosure provide a generator. The generator includes an LLC resonant circuit configured to generate a sinusoidal input signal by filtering out harmonic components of a pulse-width modulated (PWM) input signal. The generator also includes a transformer having a primary coil and a secondary coil. The transformer is configured to receive, at the primary coil, the sinusoidal input signal from the LLC resonant circuit to generate a magnetic field, and induce a sinusoidal output signal at the secondary coil based on electromagnetic induction associated with the magnetic field. The generator also includes a transducer configured to convert the sinusoidal output signal into mechanical vibrations that drive an output device.

Description

GENERATOR AND METHOD OF USECROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to U.S. Provisional Patent Application No. 63 / 690,795, filed September 4, 2024, the entire contents of which are hereby incorporated by reference as if fully set forth in this description.BACKGROUND

[0002] Generators can be used to supply power to different loads. For example, a generator can transform alternating current (AC) electrical energy from a power source, such as a wall outlet, to electrical energy for energizing a transducer. The transducer may convert a power signal (e.g., the electrical energy) into vibrations that can be used for a variety of practical applications.

[0003] Typically, generators are relatively large in size and are equipped with a large analog section. As a result, generators may require a large amount of electrical components. For example, a generator may require a power factor control wide-voltage power supply unit, one or more filtering components (e.g., capacitor banks) to reduce harmonics of input power signals, etc. The power factor control wide-voltage power supply unit and the filtering components may increase costs associated with manufacturing generators and may also increase design complexity of the generators.SUMMARY

[0004] Various embodiments of the present disclosure provide a generator for a welding machine and method of use. In some embodiments, the welding machine is a strapping device. The disclosed embodiments include an LLC resonant circuit, which reduces the number ofcomponents of the generator and the size of the generator. In some embodiments, the LLC resonant circuit is any inductor-capacitor resonant circuit that generates a sinusoidal input signal by fdtering out harmonic components of a pulse-width modulated (PWM) signal. In some such embodiments, the LLC resonant circuit includes at least two inductors (L) and at least one capacitor (C).

[0005] In one embodiment, a generator for a welding machine includes an LLC resonant circuit configured to generate a sinusoidal input signal by filtering out harmonic components of a PWM input signal. The generator also includes a transformer including a primary coil and a secondary coil. The transformer is configured to receive, at the primary coil, the sinusoidal input signal from the LLC resonant circuit to generate a magnetic field. The transformer is also configured to induce a sinusoidal output signal at the secondary coil based on electromagnetic induction associated with the magnetic field. The generator also includes a transducer configured to convert the sinusoidal output signal into mechanical vibrations that drive an output device.

[0006] In one embodiment, a method includes generating, by an LLC resonant circuit of a generator, a sinusoidal input signal by filtering out harmonic components of a PWM input signal. The method also includes inducing, via electromagnetic induction, a sinusoidal output signal at a secondary coil of a transformer of the generator by providing the sinusoidal input signal to a primary coil of the transformer. The method also includes converting, by a transducer of the generator, the sinusoidal output signal into mechanical vibrations that drive an output device.BRIEF DESCRIPTION OF THE FIGURES

[0007] Figure 1 is a block diagram of one example embodiment of a system that generates mechanical vibrations using an LLC resonant circuit.

[0008] Figure 2 is a diagram of the LLC resonant circuit used in the system of Figure 1.

[0009] Figure 3 is a diagram of a transformer used in the system of Figure 1.

[0010] Figure 4 is a diagram of a sonotrode that is powered using the LLC resonant circuit of Figure 2.

[0011] Figure 5 is a block diagram of another system that generates mechanical vibrations using an LLC resonant circuit.

[0012] Figure 6A is a diagram of a switching network having a full-bridge topology.

[0013] Figure 6B is a diagram of a switching network having a half-bridge topology.

[0014] Figure 7 is a diagram of a user interface for performing a resonance frequency search for a first welding operation.

[0015] Figure 8 is a diagram of a user interface for performing a resonance frequency search for a second welding operation.

[0016] Figure 9 is a flowchart showing an example process of the present disclosure for generating mechanical vibrations.

[0017] Figure 10 is a flowchart showing an example process of the present disclosure for performing a resonance frequency search for welding operations.DETAILED DESCRIPTION

[0018] While the systems, devices, and methods described herein may be embodied in various forms, the drawings show and the specification describes certain exemplary and non-limiting embodiments. Not all of the components shown in the drawings and described in the specification may be required, and certain implementations may include additional, different, or fewer components. Variations in the arrangement and type of the components; the shapes, sizes, and materials of the components; and the manners of connections of the components may be made without departing from the spirit or scope of the claims. Unless otherwise indicated, any directions referred to in the specification reflect the orientations of the components shown in the corresponding drawings and do not limit the scope of the present disclosure. Further, terms that refer to mounting methods, such as mounted, connected, etc., are not intended to be limited to direct mounting methods but should be interpreted broadly to include indirect and operably mounted, connected, and like mounting methods. This specification is intended to be taken as a whole and interpreted in accordance with the principles of the present disclosure and as understood by one of ordinary skill in the art.

[0019] Figure 1 is a block diagram of a system 100 that generates mechanical vibrations using an LLC resonant circuit. In some embodiments, the system 100 generates ultrasonic mechanical vibrations using the LLC resonant circuit. In some embodiments, the system 100 is integrated into a generator (e.g., an ultrasonic generator) for a welding machine, such as a strapping device. The system 100 includes an LLC resonant circuit 102, a transformer 104, a transducer 106 (e.g., an ultrasonic transducer), and an output device 108.

[0020] The LLC resonant circuit 102 is configured to receive a pulse-width-modulated (PWM) input signal 120. The PWM input signal 120 corresponds to a power signal (e.g., a voltage signal or a current signal) that is used to provide power to a welding machine.

[0021] The LLC resonant circuit 102 is configured to generate a sinusoidal input signal 122 by filtering out harmonic components of the PWM input signal 120. Thus, the LLC resonant circuit 102 filters out square wave harmonics of the PWM input signal 120 such that the sinusoidal input signal 122 is a sine wave of the fundamental switching frequency of a switching network that provides the PWM input signal 120. The sinusoidal input signal 122 (e.g., an input power signal) is provided to the transformer 104. In some embodiments, the LLC resonant circuit 102 includes a resonant capacitor (CR), a resonant inductor (LR) in series with the resonant capacitor, and a magnetizing inductor (LM) in parallel with the resonant capacitor (CR) and the resonant inductor (LR).

[0022] The transformer 104 includes a primary coil 112 and a secondary coil 114. The primary coil 112 is configured to receive the sinusoidal input signal 122 from the LLC resonant circuit 102. Based on the sinusoidal input signal 122, the primary coil 112 of the transformer 104 can generate a magnetic field. The secondary coil 114 is configured to induce a sinusoidal output signal 124 based on electromagnetic induction associated with the magnetic field generated by the primary coil 112.

[0023] The transformer 104 is configured to transform a primary voltage associated with the sinusoidal input signal 122 to a secondary voltage associated with the sinusoidal output signal 124. In some embodiments, the transformer is a step-up transformer. The secondary coil 114 is configured to provide the sinusoidal output signal 124 to the transducer 106. In some embodiments, the secondary coil 114 may be coupled, in parallel, to an oscillating circuit 302.The oscillating circuit 302 may include a resonant circuit (not shown) and an overvoltage limiter (not shown). In these embodiments, the sinusoidal output signal 124 may be a resulting output signal of the oscillating circuit 302. The oscillating circuit 302 may compensate for parasitic effects that may disturb measurements associated with an analog-to-digital converter, such as the analog-to-digital converter 540 of Figure 5.

[0024] The transducer 106 is configured to convert the sinusoidal output signal 124 into mechanical vibrations 126 that drive an output device 108. In some embodiments, the output device 108 includes a welding contact, and the mechanical vibrations 126 give energy to the welding contact in the form of heat. In such embodiments, the heat applied to the welding contact is used for welding applications (e.g., metal welding, plastic welding, etc.). The technology may also be used for non-welding applications, such as ultrasonic sieving, ultrasonic cleaning, ultrasonic cutting, etc.

[0025] In some embodiments, the system 100 reduces manufacturing costs compared to manufacturing costs associated with other generators without an LLC resonant circuit, as fewer components are used in the system 100 than in other generators. The system 100 also enables a more compact design, compared to other generators that have large analog sections.

[0026] Figure 2 is a diagram of the LLC resonant circuit 102. The LLC resonant circuit 102 is a resonant inverter with three reactive components (e.g., the capacitor 210, the inductor 220, and the inductor 230). The LLC resonant circuit 102 fdters out harmonics of the PWM input signal 120 and generates a sinusoidal voltage and current waveform (e.g., the sinusoidal input signal122). In turn, the sinusoidal voltage feeds the transformer 104 which provides voltage scaling and primary-secondary isolation.

[0027] The resonant capacitor 210, the resonant inductor 220, and the magnetizing inductor 230 are configured to filter out harmonic components of the PWM input signal 120. For example, the PWM input signal 120 has a fundamental frequency and higher harmonic components. The capacitance of the resonant capacitor 210 along with the inductance of the inductors 220, 230 operate as a filter (e g., a low-pass filter) that is tuned to the fundamental frequency of the PWM input signal 120. Thus, the higher harmonic components of the PWM input signal 120 are filtered out as the resonant capacitor 210 charges and discharges according to the fundamental frequency of the PWM input signal 120. As a result, a voltage output terminal (VLLCOUI) 204 of the LLC resonant circuit 102 receives the sinusoidal input signal 122.

[0028] Although the LLC resonant circuit 102 shown in Figure 2 includes two inductors 220, 230 and one resonant capacitor 210, in other embodiments a LLC resonant circuit includes three or more inductors and two or more resonant capacitors.

[0029] Figure 3 is a diagram of the transformer 104. The transformer 104 includes the primary coil 112 and the secondary coil 114. The primary coil 112 is configured to receive the sinusoidal input signal 122 from the LLC resonant circuit 102. A magnetic field is generated at the primary coil 112 as a result of driving the sinusoidal input signal 122 (e.g., a current signal) at the primary coil 112. The sinusoidal output signal 124 is induced at the secondary coil 114 based on electromagnetic induction associated with the magnetic field generated by the primary coil 112. Thus, in response to driving the primary coil 112 with the sinusoidal input signal 122, the sinusoidal output signal 124 is induced at the secondary coil 114.

[0030] The transformer 104 is configured to transform a primary voltage associated with the sinusoidal input signal 122 to a secondary voltage associated with the sinusoidal output signal 124. In some embodiments, the secondary voltage associated with the sinusoidal output signal 124 isgreater than the primary voltage associated with the sinusoidal input signal 122 by approximately a factor of fifty (50). In some embodiments, as depicted in Figure 3, the secondary coil 114 may be coupled, in parallel, to an oscillating circuit 302. The oscillating circuit 302 may include a resonant circuit (not shown) and an overvoltage limiter (not shown). In these embodiments, the sinusoidal output signal 124 may be a resulting output signal of the oscillating circuit 302. The oscillating circuit 302 may compensate for parasitic effects that may disturb measurements associated with an analog-to-digital converter, such as the analog-to-digital converter 540 of Figure 5.

[0031] In such embodiments, the primary voltage associated with the sinusoidal input signal 122 may range between approximately 10 root-mean-square voltage (Vrms) and 200 Vrms, and the secondary voltage associated with the sinusoidal output signal 124 may range between 500 Vrms and 5000 Vrms. However, in other embodiments, the step-up factor between the primary voltage and the secondary voltage is different. For example, if the number of turns in the secondary coil 114 increases, the step-up factor increases.

[0032] In some embodiments, the transducer 106 and the output device 108 are integrated into a sonotrode. Figure 4 is a diagram of a sonotrode 400 that is powered using the LLC resonant circuit 102. The sonotrode 400 includes the transducer 106, a sonotrode body 402, and the output device 108. The transducer 106 is powered by the sinusoidal output signal 124. The transducer 106 is configured to convert high-frequency electrical signals (e.g., the sinusoidal output signal 124) received from the transformer 104 into high-frequency mechanical vibrations. In some embodiments, the high-frequency mechanical vibrations may be in the ultrasound range, such as 20 kilohertz and higher. In other embodiments, the high-frequency mechanical vibrations may range from 50 hertz to 200 kilohertz.

[0033] The transducer 106 is coupled to the sonotrode body 402, and the sonotrode body 402 is sized and shaped to transmit the mechanical vibrations generated by the transducer 106 to the output device 108. Thus, in Figure 4, the transducer 106 is configured to convert the sinusoidal output signal 124 into mechanical vibrations that drive the output device 108.

[0034] The output device 108 is a welding contact of the sonotrode 400. In some embodiments, the output device 108 includes sonotrode teeth 410. Accordingly, in some embodiments, the transducer 106 is configured to convert high-frequency electrical signals (e.g., the sinusoidal output signal 124) into mechanical vibration of the sonotrode teeth 410 at ultrasonic frequencies.

[0035] In some embodiments, the transducer 106 includes a stack of piezoelectric transducers attached to a tapering metal rod of a sonotrode. The end of the rod is applied to the output device 108. The sinusoidal output signal 124 is applied to the stack of piezoelectric transducers, causing the stack of piezoelectric transducers to expand and contract, which gives energy to the welding contact in the form of heat. The heat applied to the output device 108 is used for welding strap.

[0036] Figure 5 is a block diagram of a system 500 that generates mechanical vibrations using an LLC resonant circuit. In some embodiments, the system 500 is integrated into a generator for a welding machine. The system 500 includes components of the system 100. For example, the system 500 includes the LLC resonant circuit 102, the transformer 104, the transducer 106, and the output device 108. The system 500 also includes a controller 502 and a switching network 504. In some embodiments, a frequency of the PWM input signal 120 is equal to a fundamental switching frequency of the switching network 504 (which mirrors a resonant frequency of the sonotrode 400) that provides the PWM input signal 120 to the LLC resonant circuit 102.

[0037] An input voltage source 510 is coupled to the controller 502. The input voltage source 510 is a direct-current voltage source. In some embodiments, an input voltage of the input voltage source is between 12 volts and 60 volts. In some such embodiments, the input voltage of the input voltage source 510 is 24 volts. In other embodiments, the input voltage source 510 may be an alternating current power supply (e.g., a single phase power supply or a three-phase power supply). In some embodiments the input power source 510 may be an alternating current power supply with built-in rectification and power factor control.

[0038] The controller 502 includes a microprocessor 550 and a digital signal processor 552. The controller 502 is configured to control a switching frequency of the switching network 504 based on measured feedback associated with the sinusoidal output signal 124.

[0039] The switching network 504 is configured to (i) receive an input voltage signal from the input voltage source, (ii) generate the PWM input signal 120 based on the input voltage signal, and (iii) provide the PWM input signal 120 to the LLC resonant circuit 102. In some embodiments, the switching network 504 has a full-bridge topology, as best shown in Figure 6A. In other embodiments, the switching network 504 has a half-bride topology, as best shown in Figure 6B.

[0040] During operation, one or more analog-to-digital converters 540 are configured to receive the sinusoidal output signal 124. The one or more analog-to-digital converters 540 are configured to generate one or more measurements 542 indicative of characteristics of the sinusoidal output signal 124. For example, the one or more measurements 542 include a voltage measurement of the sinusoidal output signal 124 or a current measurement of the sinusoidal output signal 124. The one or more analog-to-digital converters 540 are configured to provide the one or more measurements 542 to the controller 502. In some embodiments, each analog-to-digital converter 540 of the one or more analog-to-digital converters 540 is separately set up.

[0041] The controller 502 is configured to (i) receive the one or more measurements 542 from the one or more analog-to-digital converters 540 and (ii) control a switching frequency of the switching network 504 based on the one or more measurements 542. To control the switching frequency of the switching network 504, the controller 502 is configured to determine, based on the one more measurements 542, a resonant frequency of the output device 108. For example, based on the voltage measurement of the sinusoidal output signal 124 and / or the current measurement of the sinusoidal output signal 124, the digital signal processor 552 determines the resonant frequency of the sonotrode 400. In some embodiments, the resonant frequency of the output device 108 is determined from a calculated power derived from the voltage and the current measurements.

[0042] The controller 502 (e.g., the microprocessor 550) is configured to adjust the switching frequency of the switching network 504 based on the resonant frequency of the sonotrode 400. For example, the controller 502 adjusts the switching frequency of the switching network 504 such that the PWM input signal 120 switches at a zero crossing of the sinusoidal output signal 124 (e.g., the sinusoidal voltage). Thus, the controller 502 performs fast calculations to control and regulate the switching network 504 using a closed-loop configuration based on the one or more measurements 542 (e g., current and voltage measurements) that are fed to the digital signal processor 552.

[0043] The power flow of the system 500 (e.g., a LLC converter) is controlled by modulating the primary-side PWM in relation to the resonance of the LLC resonant circuit 102. The measuring points (e.g., the resonant frequency) at the load output enable a closed-loop control system. For example, the voltage and current measurements 542 are used by the controller 502 to determine the resonant frequency of the transducer 106. The controller 502 uses the resonant frequency ofthe transducer 106 to adjust the switching frequency of the switching network 504 such that power consumption at the resonance frequency is significantly reduced compared to other generators without an LLC resonant circuit. In the system 500, mismatch between the resonant frequency of the transducer 106 and the switching frequency is reduced, which leads to reduced power consumption of the disclosed generator.

[0044] The system 500 reduces analog requirements, as processing is based on digital technology. For example, the measured values (e.g., the voltages and currents of the transducer) are processed with fast analog-to-digital converters 540. In some embodiments, the analog-to- digital converters 540 may can process 1.5 mega-samples per second. For example, the analog- to-digital converters 540 are integrated into a field-programmable gate array (FPGA) and the samples are evaluated by the digital signal processor 552. Additionally, because a DC input voltage source 510 is used as opposed to an AC input voltage source, capacitor banks, other filtering components, and power factor control is not needed at the input of the system 500, which reduces size and design complexity of the disclosed generator.

[0045] In some embodiments, a system that generates mechanical vibrations using an LLC resonant circuit is implemented using a single FPGA device. In some such embodiments, the microprocessor 550 and / or the digital signal processor 552 is implemented using dedicated hardware or dedicated software (e.g., instructions executable by a processor). In some embodiments, the processor is the controller 502.

[0046] Figure 6A is a diagram of a switching network having a full-bridge topology 504A. In some embodiments, the full-bridge topology 504A is integrated into the switching network 504.

[0047] In the full-bridge topology 504A, a first terminal of the input voltage source 510 is coupled to a drain of a transistor 602 and to a drain of a transistor 606. A second terminal of the input voltage source 510 is coupled to a source of a transistor 604 and to a source of a transistor 608. A source of the transistor 602 is coupled to a drain of the transistor 604 at a first output node of the full-bridge topology 504A, and a source of the transistor 606 is coupled to a drain of the transistor 608 at a second output node of the full-bridge topology 504A. The output nodes of the full-bridge topology 504A provide a differential output (e.g., the PWM input signal 120) that is provided to the LLC resonant circuit 102.

[0048] In the embodiment shown in Figure 6A, the transistors 602, 604, 608, 608 are pull-down transistors. For example, the transistors 602, 604, 608, 608 are n-type metal-oxide-semiconductor (NMOS) transistors. In some embodiments, the voltage of the PWM input signal 120 is based on gate voltages applied to gates of the transistors 602, 604, 608, 608. For example, when a logical high gate voltage is applied to the gates of the transistors 602, 608 and a logical low gate voltage is applied to the transistors 604, 606, the transistors 602, 608 are activated (e.g., conduct) and the transistors 604, 606 are deactivated. As a result, the PWM input signal 120 has a first voltage level (e.g., a positive polarity of the input voltage level) at the differential output.

[0049] When a switch occurs, the PWM input signal 120 has a second voltage level (e.g., a negative polarity of the input voltage level) at the differential output. For example, when a logical low gate voltage is applied to the gates of the transistors 602, 608 and a logical high gate voltage is applied to the gates of the transistors 604, 606, the transistors 602, 608 are deactivated and the transistors 604, 606 are activated. As a result, the PWM input signal 120 has the second voltage level.

[0050] In some embodiments, the controller 502 controls the switching frequency of the fullbridge topology 504A. For example, the controller 502 is configured to bias the gate voltages of the full-bridge topology 504A to perform the switching operation described above. The controller 502 is configured to adjust the switching frequency of the switching network 504 based on the resonant frequency of the sonotrode 400. For example, the controller 502 adjusts the switching frequency of the switching network 504 such that the PWM input signal 120 switches at a zero crossing of the sinusoidal output signal 124. Thus, the controller 502 performs fast calculations to control and regulate the switching network 504 using a closed-loop configuration based on the one or more measurements 542 that are fed to the digital signal processor 552.

[0051] Figure 6B is a diagram of a switching network having a half-bridge topology 504B. In some embodiments, the half-bridge topology 504B depicted in Figure 6B is integrated into the switching network 504.

[0052] In the half-bridge topology 504A, a first terminal of the input voltage source 510 is coupled to a drain of a transistor 612. A second terminal of the input voltage source 510 is coupled to a source of a transistor 614. A source of the transistor 612 is coupled to a drain of the transistor 614 at a first output node of the half-bridge topology 504B, and a second output node of the halfbridge topology 504B is coupled to the source of the transistor 614. The output nodes of the halfbridge topology 504B provide a differential output (e.g., the PWM input signal 120) that is provided to the LLC resonant circuit 102.

[0053] In the embodiment shown in Figure 6B, the transistors 612, 614 are pull-down transistors.For example, the transistors 612, 614 are NMOS transistors. In some embodiments, the voltage of the PWM input signal 120 is based on gate voltages applied to gates of the transistors 612, 614. For example, when a logical high gate voltage is applied to the gate of the transistor 612 and alogical low gate voltage is applied to the transistor 614, the transistor 612 is activated (e.g., conducts) and the transistor 614 is deactivated. As a result, the PWM input signal 120 has a first voltage level (e.g., a positive polarity of the input voltage level) at the differential output.

[0054] When a switch occurs, the PWM input signal 120 has a second voltage level (e.g., a zero voltage level) at the differential output. For example, when a logical low gate voltage is applied to the gate of the transistor 612 and a logical high gate voltage is applied to the gate of the transistor 614, the transistor 612 is deactivated and the transistor 614 is activated. As a result, the PWM input signal 120 has the second voltage level.

[0055] In some embodiments, the controller 502 controls the switching frequency of the fullbridge topology 504A. For example, the controller 502 is configured to bias the gate voltages of the full-bridge topology 504A to perform the switching operation as described above. The controller 502 is configured to adjust the switching frequency of the switching network 504 based on the resonant frequency of the sonotrode 400. For example, the controller 502 adjusts the switching frequency of the switching network 504 such that the PWM input signal 120 switches at a zero crossing of the sinusoidal output signal 124. Thus, the controller 502 performs fast calculations to control and regulate the switching network 504 using a closed-loop configuration based on the one or more measurements 542 that are fed to the digital signal processor 552.

[0056] Figure 7 is a diagram of a user interface 700 for performing a resonance frequency search for a first welding operation. The user interface 700 includes a start frequency 702 section, a power-frequency search parameters 704 section, a frequency approximation parameters 706 section, and a weld results 708 section. In some embodiments, the user interface 700 is used to identify a resonance frequency of the sonotrode 400.

[0057] Operation of the sonotrode 400 varies based on temperature and pressure. In some embodiments, the sonotrode 400 operates according to a first manner at a first temperature (e.g., on an initial sonotrode temperature) caused by the welding operation. In other embodiments, the sonotrode 400 operates according to a second manner under pressure. Thus, operation of the sonotrode 400 varies based on two external parameters: temperature and pressure. In some embodiments, these external parameters cause the sonotrode 400 to operate outside of a resonance frequency or cause the sonotrode 400 to stop working. A user operating the sonotrode 400 outside of a resonance frequency can result in increased welding times, increased converter current, and / or increased input current. Further, a user operating the sonotrode 400 outside of a resonance frequency can result in failure of the piezoelectric transducers and / or the sonotrode 400, which shortens a service life of sonotrode 400.

[0058] The frequency search described herein identifies a resonance frequency of the sonotrode 400 to enable a user to operate the sonotrode 400 at the resonant frequency, which reduces the effects of temperature and / or pressure on the sonotrode 400. The frequency search process is supported by a phase detector.

[0059] A resonance frequency approximation process is described with respect to Figures 7 and 8. The resonance frequency approximation process is performed by a processor, such as the controller 502, the microprocessor 550, and / or the digital signal processor 552. In some embodiments, the processor executes instructions stored in a non-transitory computer-readable medium to perform the resonance frequency approximation process. The resonance frequency approximation process reduces and / or optimizes a bandwidth of a frequency search in the sonotrode 400 after each welding operation by analyzing the frequency associated with the highest effective power. Additionally, for each subsequent welding operation, the resonancefrequency approximation process utilizes the resonance frequency from a previously welding operation as a starting point to search for a new resonance frequency, resulting in a continuous approximation of the resonance frequency and a gradual reduction of a frequency search band. In some embodiments, the process of approximating the resonance frequency takes into account aging effects caused by changes in vibration behavior and changes in capacitance of the transducer.

[0060] One or more values (e.g., frequency values) depicted on the user interface 700 are illustrative of the values generated by processes performed by the processor. In some embodiments, one or more values depicted on the user interface 700 are user-selectable, as depicted by the arrows on the user interface 700.

[0061] An example of the resonance frequency approximation process for a first welding operation is described next. First, the processor determines an initial resonance frequency 710 of the sonotrode 400. The initial resonance frequency 710 corresponds to a resonance frequency of the sonotrode 400 prior to a first welding operation. In some embodiments, the initial resonance frequency 710 is recorded without mechanical pressure on the sonotrode 400 and without damping by the weld material on the sonotrode 400. In the example illustrated in Figure 7, the initial resonance frequency 710 is 1000 Hz. In some embodiments, the initial resonance frequency 710 is referred to as a cold start frequency. It should be understood that the frequency values described herein are merely for illustrative purposes and should not be construed as limiting. In other embodiments, different frequencies may be utilized.

[0062] Next, the processor adds a frequency offset 712 to the initial resonance frequency 710 to determine a first start frequency 714 for the first welding operation. In the example illustrated in Figure 7, the frequency offset 712 is 50 Hz and the first start frequency 714 is 1050 Hz. In someembodiments, the first start frequency 714 corresponds to a center of a search frequency window for determining a first resonance frequency 716 for the first welding operation. In some embodiments, the search frequency window is referred to as a first frequency range. For example, the processor performs a first resonance frequency search operation based on the first start frequency 714 to determine the first resonance frequency 716 for the first welding operation. In some embodiments, operating the sonotrode 400 at the first resonance frequency 716 results in a maximum effective power during the first welding operation.

[0063] To perform the first resonance frequency search operation, the processor determines a first frequency range that spans from a first lower limit frequency to a first higher limit frequency. For example, the processor uses a low frequency search limit 720 and a high frequency search limit 722 to determine the first frequency range. In the example illustrated in Figure 7, the low frequency search limit 720 is 100 Hz and the high frequency search limit 722 is 100 Hz. As a result, in some embodiments, the first frequency range spans from 950 Hz (e.g., the first start frequency 714 minus the low frequency search limit 720) to 1150 Hz (e.g., the first start frequency 714 plus the high frequency search limit 722). Thus, in some embodiments, the first start frequency 714 may be at the center of the first frequency range. In some embodiments, when the low frequency search limit 720 and the high frequency search limit 722 are not equal, the first start frequency 714 is not at the center of the first frequency range.

[0064] The processor determines an effective power for each frequency step in the first frequency range. In example illustrated in Figure 7, each frequency step 730 is 10 Hz. Thus, for the first frequency range (e.g., 950 Hz - 1150 Hz), the processor determines the effective power in 10 Hz increments. For example, the processor determines the effective power at 950 Hz, the effective power at 960 Hz, and the effective power at 970 Hz. The processor identifies thefrequency step in the first frequency range that results in a maximum effective power at the first resonance frequency 716. Thus, in the example illustrated in Figure 7, the first resonance frequency 716 is 980 Hz. Once the first resonance frequency 716 is identified, the controller 502 may control the switching network 504 based on first resonance frequency 716 during the first welding operation.

[0065] Figure 8 is a diagram of the user interface 700 for performing a resonance frequency search for a second welding operation (e.g., an n + 1 welding operation).

[0066] An example of the resonance frequency approximation process for a second welding operation is described next. First, the processor determines a second resonance frequency 816 for a second welding operation. To determine the second resonance frequency 816, the processor adds the frequency offset 712 to the first resonance frequency 716 to determine a second start frequency 814 for the second welding operation. Thus, the determination of the second resonance frequency 816 is based, at least in part, on the resonance frequency 716 for the first welding operation. In the example illustrated in Figure 8, the second start frequency 814 is 1030 Hz (e.g., 50 Hz plus 980 Hz).

[0067] Next, the processor performs a second resonance frequency search operation based on the second start frequency 714 to determine the second resonance frequency 816 for the second welding operation. In some embodiments, operating the sonotrode 400 at the second resonance frequency 816 results in a maximum effective power during the second welding operation.

[0068] To perform the second resonance frequency search operation, the processor determines a second frequency range that spans from a second lower limit frequency to a second higher limit frequency. For example, the processor uses a low frequency search limit 820 and a high frequencysearch limit 822 to determine the second frequency range. In the example illustrated in Figure 8, the low frequency search limit 820 is 95 Hz and the high frequency search limit 822 is 95 Hz. As a result, in some embodiments, the second frequency range spans from 935 Hz (e.g., the second start frequency 814 minus the low frequency search limit 820) to 1125 Hz (e.g., the second start frequency 814 plus the high frequency search limit 822).

[0069] The low and high frequency search limits 820, 822 are 5 Hz less than the corresponding search limits in the frequency approximation process for the first welding operation. For example, a low / high frequency search approximation step 732 indicates that, for each welding operation, the search limits are reduced by 5 Hz to narrow the search. In some embodiments, a minimum search frequency approximation band 734 is used so that search limits do not become narrow. In the example illustrated in Figure 8, the minimum search frequency approximate band 734 is 50 Hz.

[0070] The processor determines an effective power for each frequency step in the second frequency range. In example illustrated in Figure 8, each frequency step 730 is equal to 10 Hz. Thus, for the second frequency range (e.g., 935 Hz - 1125 Hz), the processor determines the effective power in 10 Hz increments. For example, the processor determines the effective power at 935 Hz, the effective power at 945 Hz, and the effective power at 955 Hz. In some embodiments, the processor identifies the frequency step in the second frequency range that results in a maximum effective power as the second resonance frequency 816. Thus, in the example illustrated in Figure 8, the second resonance frequency 816 is 955 Hz. Once the second resonance frequency 816 is identified, the controller 502 controls the switching network 504 based on second resonance frequency 816 during the second welding operation.

[0071] In some embodiments, in the event of an error in a welding operation, the sonotrode 400 reset to the initial resonance frequency 710 and the frequency search limits are reset to the lowfrequency search limit 720 and the high frequency search limit 722. Example errors in the welding operation include exceeding predetermined welding time in energy mode, exceeding the energy limits in time mode, falling below the energy limits in time mode, insufficient power consumption of the converter and / or sonotrode 400, overvoltage on the primary side of the transformer 104, overvoltage on the secondary side of the transformer 104, overcurrent on the primary side of the transformer 104, and overcurrent on the secondary side of the transformer 104.

[0072] In some embodiments, after a weld inactivity approximation reset timer 736 expires, the sonotrode 400 resets to the initial resonance frequency 710 and the frequency search limits are reset to the low frequency search limit 720 and the high frequency search limit 722. Thus, in the examples illustrated in Figures 7 and 8, if 300 seconds elapse between welding operations, the sonotrode 400 resets to the initial resonance frequency 710 and the frequency search limits are reset to the low frequency search limit 720 and the high frequency search limit 722. It should be understood that the weld inactivity approximation reset timer 736 may be adjusted to a different time frame.

[0073] Although the resonance frequency approximation process is described above with respect to the sonotrode 400, in other embodiments the resonance frequency approximation process is performed in connection with other generators.

[0074] Figure 9 is a flowchart showing a process 900 for generating mechanical vibrations for a welding machine. In some embodiments, the system 100 and / or the system 500 performs the process 900.

[0075] The process 900 begins by generating, by an LLC resonant circuit of a generator, a sinusoidal input signal by filtering out harmonic components of a PWM input signal, as block 902indicates. In some embodiments, the LLC resonant circuit 102 generates the sinusoidal input signal 122 by filtering out harmonic components of the PWM signal 120.

[0076] The process 900 continues by inducing, via electromagnetic induction, a sinusoidal output signal at a secondary coil of a transformer of the generator by providing the sinusoidal input signal to a primary coil of the transformer, as block 904 indicates. In some embodiments, the transformer 104 induces, via electromagnetic induction, the sinusoidal output signal 124 at the secondary coil 114 by providing the sinusoidal input signal 122 to the primary coil 112.

[0077] The process 900 continues by converting, by a transducer of the generator, the sinusoidal output signal into mechanical vibrations that drive an output device, as block 906 indicates. In some embodiments, the transducer 106 converts the sinusoidal output signal 124 into mechanical vibrations 126 that drive the output device 108.

[0078] Figure 10 is a flowchart showing a process 1000 for performing a resonance frequency search for welding operations. In some embodiments, the system 100 and / or the system 500 performs the process 1000.

[0079] The process 1000 begins by determining, by a controller of a generator, an initial resonance frequency of the generator, as block 1002 indicates. The initial resonance frequency corresponds to a resonance frequency of the generator prior to a first welding operation. In some embodiments, the controller 502 determines the initial resonance frequency 710 of the sonotrode 400. The initial resonance frequency 710 corresponds to the resonance frequency of the sonotrode 400 prior to the first welding operation.

[0080] The process 1000 continues by adding a frequency offset to the initial resonance frequency to determine a first start frequency for the welding operation, as block 1004 indicates.In some embodiments, the controller 502 adds the frequency offset 712 to the initial resonance frequency 710 to determine the first start frequency 714 for the welding operation.

[0081] The process 1000 continues by performing a first resonance frequency search operation based on the first start frequency to determine the first resonance frequency for the first welding operation, as block 1006 indicates. In some embodiments, the first resonance frequency results in a maximum effective power during the first welding operation. In some embodiments, the controller 502 performs the first resonance frequency search operation based on the first start frequency 714 to determine the first resonance frequency 716 for the first welding operation. In some embodiments, operating the generator at the first resonance frequency 716 results in a maximum effective power during the first welding operation.

[0082] The process 1000 continues by adding the frequency offset to the first resonance frequency to determine a second start frequency for a second welding operation (e.g., an n +1 welding cycle), as block 1008 indicates. In some embodiments, the controller 502 adds the frequency offset 712 to the first resonance frequency 716 to determine the second start frequency 814 for the second welding operation.

[0083] The process 1000 continues by performing a second resonance frequency search operation based on the second start frequency to determine a second resonance frequency for the second welding operation as block 1010 indicates. In some embodiments, the second resonance frequency results in a maximum effective power during the second welding operation. In some embodiments, the controller 502 performs the second resonance frequency search operation based on the second start frequency 814 to determine the second resonance frequency 816 for the second welding operation. Further, in some embodiments, operating the generator at the second resonance frequency 816 results in a maximum effective power during the second welding operation.

[0084] Thus, in various embodiments, the present disclosure provides a generator for a welding machine. The generator comprises an LLC resonant circuit configured to generate a sinusoidal input signal by filtering out harmonic components of a PWM input signal. The generator also includes a transformer comprising a primary coil and a secondary coil. The transformer is configured to receive, at the primary coil, the sinusoidal input signal from the LLC resonant circuit to generate a magnetic field. The transformer is also configured to induce a sinusoidal output signal at the secondary coil based on electromagnetic induction associated with the magnetic field. The generator also includes a transducer configured to convert the sinusoidal output signal into mechanical vibrations that drive an output device.

[0085] In various such embodiments of the generator, the transducer comprises a sonotrode.

[0086] In various such embodiments of the generator, the transformer corresponds to a step-up transformer that is configured to transform a primary voltage associated with the sinusoidal input signal to a secondary voltage associated with the sinusoidal output signal.

[0087] In various such embodiments of the generator, the primary voltage is approximately 21 root-mean-square voltage (Vims), and the secondary voltage is approximately 1,000 Vrms.

[0088] In various such embodiments of the generator, the generator further comprises an input voltage source. The generator also includes a switching network coupled to the input voltage source and to the LLC resonant circuit. The switching network is configured to receive an input voltage signal from the input voltage source. The switching network is also configured to generate the PWM input signal based on the input voltage signal. The switching network is also configured to provide the PWM input signal to the LLC resonant circuit.

[0089] In various such embodiments of the generator, the switching network has one of: a fullbridge topology and a half-bridge topology.

[0090] In various such embodiments of the generator, the input voltage source is a direct-current voltage source or an alternating-current voltage source.

[0091] In various such embodiments of the generator, an input voltage of the input voltage source is 12-60 volts.

[0092] In various such embodiments of the generator, an input voltage of the input voltage source is 24 volts.

[0093] In various such embodiments of the generator, the generator further comprises a processor configured to receive one or more measurements indicative of characteristics of the sinusoidal output signal. The processor is also configured to control a switching frequency of the switching network based on the one or more measurements.

[0094] In various such embodiments of the generator, the one or more measurements comprise one of: a voltage measurement of the sinusoidal output signal and a current measurement of the sinusoidal output signal.

[0095] In various such embodiments of the generator, the generator further comprises one or more analog-to-digital converters that are configured to generate the one or more measurements.

[0096] In various such embodiments of the generator, to control the switching frequency of the switching network, the processor is configured to determine, based on the one or more measurements, a resonant frequency of the output device and adjust the switching frequency of the switching network based on the resonant frequency of the output device.

[0097] In various such embodiments of the generator, the LLC resonant circuit comprises a resonant capacitor, a resonant inductor in series with the resonant capacitor, and a magnetizing inductor in parallel with the resonant capacitor and the resonant inductor.

[0098] In various such embodiments of the generator, the PWM input signal corresponds to one of: a voltage signal and a current signal.

[0099] In various such embodiments of the generator, the sinusoidal input signal corresponds to one of: a voltage signal and a current signal.

[0100] In various such embodiments of the generator, the sinusoidal output signal corresponds to one of: a voltage signal and a current signal.

[0101] In various such embodiments of the generator, the LLC resonant circuit comprises two inductors and a capacitor.

[0102] In various embodiments, the present disclosure provides a method. The method comprises generating, by an LLC resonant circuit of a generator, a sinusoidal input signal by filtering out harmonic components of a PWM input signal. The method comprises inducing, via electromagnetic induction, a sinusoidal output signal at a secondary coil of a transformer of the generator by providing the sinusoidal input signal to a primary coil of the transformer. The method comprises converting, by a transducer of the generator, the sinusoidal output signal into mechanical vibrations that drive an output device.

[0103] In various such embodiments of the method, the transducer comprises a sonotrode.

[0104] In various such embodiments of the method, the transformer corresponds to a step-up transformer that is configured to transform a primary voltage associated with the sinusoidal input signal to a secondary voltage associated with the sinusoidal output signal.

[0105] In various such embodiments of the method, the primary voltage is approximately 21 root-mean-square voltage (Vrms), and the secondary voltage is approximately 1,000 Vrms.

[0106] In various such embodiments of the method, the method comprises receiving, at a switching network, an input voltage signal from an input voltage source, generating the PWM input signal based on the input voltage signal, and providing the PWM input signal to the LLC resonant circuit.

[0107] In various such embodiments of the method, the switching network has one of a fullbridge topology and a half-bridge topology.

[0108] In various such embodiments of the method, the input voltage source is a direct-current voltage source.

[0109] In various such embodiments of the method, an input voltage of the input voltage source is 12-60 volts.

[0110] In various such embodiments of the method, an input voltage of the input voltage source is 24 volts.[0U1] In various such embodiments of the method, the method comprises receiving, at a processor, one or more measurements indicative of characteristics of the sinusoidal output signal. The method also comprises controlling, by the processor, a switching frequency of the switching network based on the one or more measurements.

[0112] In various such embodiments of the method, the one or more measurements comprise one of: a voltage measurement of the sinusoidal output signal and a current measurement of the sinusoidal output signal.

[0113] In various such embodiments of the method, the method comprises generating, by one or more analog-to-digital converters, the one or more measurements.

[0114] In various such embodiments of the method, to control the switching frequency of the switching network, the method comprises determining, based on the one or more measurements, a resonant frequency of the output device and adjusting the switching frequency of the switching network based on the resonant frequency of the output device.

[0115] In various such embodiments of the method, the LLC resonant circuit comprises a resonant capacitor, a resonant inductor in series with the resonant capacitor, and a magnetizing inductor in parallel with the resonant capacitor and the resonant inductor.

[0116] In various such embodiments of the method, the PWM input signal corresponds to one of: a voltage signal and a current signal.

[0117] In various such embodiments of the method, the sinusoidal input signal corresponds to one of: a voltage signal and a current signal.

[0118] In various such embodiments of the method, the sinusoidal output signal corresponds to one of: a voltage signal and a current signal.

[0119] In various such embodiments of the method, the method comprises determining a first resonance frequency for a first welding operation. Determining the first resonance frequency comprises determining, by a controller of the generator, an initial resonance frequency of thegenerator. The initial resonance frequency corresponds to a resonance frequency of the generator prior to the first welding operation. Determining the first resonance frequency comprises adding a frequency offset to the initial resonance frequency to determine a first start frequency for the first welding operation. Determining the first resonance frequency comprises performing a first resonance frequency search operation based on the first start frequency to determine the first resonance frequency for the first welding operation.

[0120] In various such embodiments of the method, performing the first resonance frequency search operation comprises determining a first frequency range that spans from a first lower limit frequency to a first higher limit frequency. The first start frequency is between the first lower limit frequency and the first higher limit frequency. Performing the first resonance frequency search operation comprises determining an effective power for each frequency step in the first frequency range. Performing the first resonance frequency search operation comprises identifying the frequency step in the first frequency range that results in a maximum effective power as the first resonance frequency.

[0121] In various such embodiments of the method, the method comprises determining a second resonance frequency for a second welding operation. Determining the second resonance frequency comprises adding the frequency offset to the first resonance frequency to determine a second start frequency for the second welding operation. Determining the second resonance frequency comprises performing a second resonance frequency search operation based on the second start frequency to determine the second resonance frequency for the second welding operation.

[0122] In various such embodiments of the method, performing the second resonance frequency search operation comprises determining a second frequency range that spans from a second lower limit frequency to a second higher limit frequency. The second start frequency is between thesecond lower limit frequency and the second higher limit frequency. Performing the second resonance frequency search operation comprises determining an effective power for each frequency step in the second frequency range. Performing the second resonance frequency search operation comprises identifying the frequency step in the second frequency range that results in a maximum effective power as the second resonance frequency.

[0123] In various embodiments, the present disclosure provides a method. The method comprises determining, by a controller of a generator, an initial resonance frequency of the generator, wherein the initial resonance frequency corresponds to a resonance frequency of the generator prior to a welding operation. The method comprises adding a frequency offset to the initial resonance frequency to determine a start frequency for the welding operation. The method comprises performing a resonance frequency search operation based on the start frequency to determine the resonance frequency for the welding operation.

[0124] In various embodiments, the present disclosure provides a non-transitory computer- readable medium. The non-transitory computer readable medium includes instructions that, when executed by a controller, cause the controller to perform operations. The operations include determine an initial resonance frequency of a generator, wherein the initial resonance frequency corresponds to a resonance frequency of the generator prior to a welding operation. The operations also include add a frequency offset to the initial resonance frequency to determine a start frequency for the welding operation. The operations also include perform a first resonance frequency search operation based on the start frequency to determine the resonance frequency for the welding operation.

[0125] Various changes and modifications to the above-described embodiments described herein will be apparent to those skilled in the art. These changes and modifications can be madewithout departing from the spirit and scope of this present subject matter and without diminishing its intended advantages. Not all of the depicted components described in this disclosure may be required, and some implementations may include additional, different, or fewer components from those expressly described in this disclosure. Variations in the arrangement and type of the components; the shapes, sizes, and materials of the components; and the manners of attachment and connections of the components may be made without departing from the spirit or scope of the claims as set forth herein. Also, unless otherwise indicated, any directions referred to herein reflect the orientations of the components shown in the corresponding drawings and do not limit the scope of the present disclosure. This specification is intended to be taken as a whole and interpreted in accordance with the principles of the invention as taught herein and understood by one of ordinary skill in the art.

Claims

CLAIMS1. A generator for a welding machine, the generator comprising: an LLC resonant circuit configured to generate a sinusoidal input signal by filtering out harmonic components of a pulse-width-modulated (PWM) input signal; a transformer comprising a primary coil and a secondary coil, the transformer configured to: receive, at the primary coil, the sinusoidal input signal from the LLC resonant circuit to generate a magnetic field; and induce a sinusoidal output signal at the secondary coil based on electromagnetic induction associated with the magnetic field; and a transducer configured to convert the sinusoidal output signal into mechanical vibrations that drive an output device.

2. The generator of claim 1, wherein the transducer comprises a sonotrode.

3. The generator of claim 1, wherein the transformer corresponds to a step-up transformer that is configured to transform a primary voltage associated with the sinusoidal input signal to a secondary voltage associated with the sinusoidal output signal.

4. The generator of claim 1, wherein the generator comprises an ultrasonic generator, wherein the transducer comprises an ultrasonic transducer, and wherein the mechanical vibrations are ultrasonic mechanical vibrations.

5. The generator of claim 1, further comprising: an input voltage source; and a switching network coupled to the input voltage source and to the LLC resonant circuit, wherein the switching network is configured to: receive an input voltage signal from the input voltage source; generate the PWM input signal based on the input voltage signal; and provide the PWM input signal to the LLC resonant circuit.

6. The generator of claim 5, wherein the switching network has one of: a full-bridge topology and a half-bridge topology.

7. The generator of claim 5, wherein the input voltage source is a direct-current voltage source or an alternating-current voltage source.

8. The generator of claim 5, further comprising a processor configured to: receive one or more measurements indicative of characteristics of the sinusoidal output signal; and control a switching frequency of the switching network based on the one or more measurements.

9. The generator of claim 8, wherein the one or more measurements comprise one of: a voltage measurement of the sinusoidal output signal and a current measurement of the sinusoidal output signal.

10. The generator of claim 8, further comprising one or more analog-to-digital converters that are configured to generate the one or more measurements.

11. The generator of claim 8, wherein, to control the switching frequency of the switching network, the processor is configured to: determine, based on the one or more measurements, a resonant frequency of the output device; and adjust the switching frequency of the switching network based on the resonant frequency of the output device.

12. The generator of claim 1, wherein the LLC resonant circuit comprises: a resonant capacitor; a resonant inductor in series with the resonant capacitor; and a magnetizing inductor in parallel with the resonant capacitor and the resonant inductor.

13. The generator of claim 1, wherein the PWM input signal corresponds to one of: a voltage signal and a current signal.

14. The generator of claim 1, wherein the sinusoidal input signal corresponds to one of: a voltage signal and a current signal.

15. The generator of claim 1, wherein the sinusoidal output signal corresponds to one of: a voltage signal and a current signal.

16. The generator of claim 1, wherein the LLC resonant circuit comprises two inductors and a capacitor.

17. A method comprising: generating, by an LLC resonant circuit of a generator, a sinusoidal input signal by filtering out harmonic components of a pulse-width-modulated (PWM) input signal; inducing, via electromagnetic induction, a sinusoidal output signal at a secondary coil of a transformer of the generator by providing the sinusoidal input signal to a primary coil of the transformer; and converting, by a transducer of the generator, the sinusoidal output signal into mechanical vibrations that drive an output device.

18. The method of claim 17, wherein the transducer comprises a sonotrode.

19. The method of claim 17, further comprising: receiving, by a processor of the generator, one or more measurements indicative of characteristics of the sinusoidal output signal; and controlling, by the processor and based on the one or more measurements, a switching frequency of a switching network of the generator, wherein the switching network provides the PWM input signal to the LLC resonant circuit.

20. The method of claim 17, further comprising determining a first resonance frequency for a first welding operation, wherein determining the first resonance frequency comprises:determining, by a controller of the generator, an initial resonance frequency of the generator, wherein the initial resonance frequency corresponds to a resonance frequency of the generator prior to the first welding operation; adding a frequency offset to the initial resonance frequency to determine a first start frequency for the first welding operation; and performing a first resonance frequency search operation based on the first start frequency to determine the first resonance frequency for the first welding operation.

21. The method of claim 20, wherein performing the first resonance frequency search operation comprises: determining a first frequency range that spans from a first lower limit frequency to a first higher limit frequency, wherein the first start frequency is between the first lower limit frequency and the first higher limit frequency; determining an effective power for each frequency step in the first frequency range; and identifying the frequency step in the first frequency range that results in a maximum effective power as the first resonance frequency.

22. The method of claim 20, further comprising determining a second resonance frequency for a second welding operation, wherein determining the second resonance frequency comprises: adding the frequency offset to the first resonance frequency to determine a second start frequency for the second welding operation; andperforming a second resonance frequency search operation based on the second start frequency to determine the second resonance frequency for the second welding operation.

23. The method of claim 22, wherein performing the second resonance frequency search operation comprises: determining a second frequency range that spans from a second lower limit frequency to a second higher limit frequency, wherein the second start frequency is between the second lower limit frequency and the second higher limit frequency; determining an effective power for each frequency step in the second frequency range; identifying the frequency step in the second frequency range that results in a maximum effective power as the second resonance frequency.

24. A method of determining a resonance frequency for a welding operation, the method comprising: determining, by a controller of a generator, an initial resonance frequency of the generator, wherein the initial resonance frequency corresponds to a resonance frequency of the generator prior to a welding operation; adding a frequency offset to the initial resonance frequency to determine a start frequency for the welding operation; and performing a resonance frequency search operation based on the start frequency to determine the resonance frequency for the welding operation.

25. A non-transitory computer-readable medium comprising instructions that, when executed by a controller, cause the controller to perform operations comprising: determine an initial resonance frequency of a generator, wherein the initial resonance frequency corresponds to a resonance frequency of the generator prior to a welding operation; add a frequency offset to the initial resonance frequency to determine a start frequency for the welding operation; and perform a first resonance frequency search operation based on the start frequency to determine the resonance frequency for the welding operation.

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