An ultrasonic power supply circuit

Abstract

The application discloses an ultrasonic power supply circuit, comprising a rectification filter circuit, a power factor correction circuit, a phase-shift full-bridge circuit, a transformer isolation circuit, a tuning circuit, an output voltage sampling circuit, an output current sampling circuit, a current grading sampling circuit, a voltage grading sampling circuit and a central processing unit connected in sequence; voltage sampling when the output voltage is greater than 200V and not greater than 200V, current sampling when the output current is greater than 5A and not greater than 5A can be realized according to the voltage grading sampling circuit; then a fuzzy PI control algorithm is used to track the inherent characteristic frequency of an ultrasonic vibration system, and the technical problem that the existing ultrasonic power supply frequency tracking mode cannot simultaneously consider the accuracy of 20V-1500V voltage sampling, and it is difficult to ensure that the frequency of the ultrasonic power supply output ultrasonic power changes in real time and accurately along with the change of the inherent characteristic frequency of the ultrasonic vibration system is solved.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic power supply technology, and in particular to an ultrasonic power supply circuit. Background Technology

[0002] An ultrasonic power supply, also called an ultrasonic generator, is used to convert electrical energy into a high-frequency alternating current signal that matches the ultrasonic transducer. It is a device used to generate and provide ultrasonic energy to the ultrasonic transducer. Ultrasonic welding technology utilizes high-frequency vibration waves transmitted to the surfaces of two objects to be welded. Under pressure, the surfaces of the two objects rub against each other, forming a fusion between molecular layers.

[0003] The presence of frequency tracking capability is a crucial indicator of the performance of an ultrasonic power supply. Frequency tracking accuracy and stability are key metrics for evaluating the quality of this function. An ultrasonic power supply needs to be able to search for the resonant frequency within a specific frequency range and track it in real-time during operation. However, the voltage of an ultrasonic power supply can rise above 1500V when deviating from the resonant point or under heavy load, while it can drop to around 20V when unloaded at the resonant point. Achieving stable and accurate frequency tracking over such a wide voltage range requires accurate sampling of this voltage range. Current ultrasonic power supplies use a single resistor divider method for voltage sampling, with a fixed transformation ratio. This method cannot simultaneously ensure the accuracy of sampling voltages from 20V to 1500V, making it difficult to guarantee that the frequency of the ultrasonic energy output from the power supply accurately follows the changes in the inherent characteristic frequency of the ultrasonic vibration system in real time, resulting in low frequency tracking accuracy. Summary of the Invention

[0004] This invention provides an ultrasonic power supply circuit to solve the technical problem that existing ultrasonic power supply frequency tracking methods cannot simultaneously ensure the accuracy of voltage sampling from 20V to 1500V, making it difficult to guarantee that the frequency of the ultrasonic power output from the ultrasonic power supply accurately follows the changes in the inherent characteristic frequency of the ultrasonic vibration system in real time, resulting in low frequency tracking accuracy.

[0005] In view of this, the present invention provides an ultrasonic power supply circuit, including a rectifier filter circuit, a power factor correction circuit, a phase-shifting full-bridge circuit, a transformer isolation circuit and a tuning circuit connected in sequence, and further including an output voltage sampling circuit, an output current sampling circuit and a voltage grading sampling circuit.

[0006] The power factor correction circuit, phase-shifted full-bridge circuit, output voltage sampling circuit, output current sampling circuit, and voltage grading sampling circuit are all connected to the central processing unit.

[0007] The voltage grading sampling circuit includes a first analog switch chip, a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor. The first end of the fifth resistor is connected to the NO pin of the first analog switch chip, and the second end is connected to the first end of the third resistor. The first end of the fourth resistor is connected to the NC pin of the first analog switch chip, and the second end is connected to the first end of the third resistor. The first, second, and third resistors are connected in series. The first resistor is connected to the current transformer of the output current sampling circuit, and the IN pin of the first analog switch chip is connected to the central processing unit.

[0008] The central processing unit is used to acquire data from the output voltage sampling circuit and the output current sampling circuit, and to control the power factor correction circuit, the phase-shifting full-bridge circuit and the voltage grading sampling circuit. Based on the phase angle of the ultrasonic transducer, a fuzzy PI control algorithm is used to track the inherent characteristic frequency of the ultrasonic vibration system.

[0009] Optionally, it also includes a current-grading sampling circuit;

[0010] The current grading sampling circuit is connected to the central processing unit;

[0011] The current grading sampling circuit includes a second analog switch chip, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, and an eleventh resistor. The first end of the sixth resistor is connected to the NC pin of the second analog switch chip, and the second end is connected to the current transformer of the output current sampling circuit. The first end of the seventh, eighth, ninth, tenth, and eleventh resistors connected in parallel is connected to the NO pin of the second analog switch chip, and the second end is connected to the output current sampling circuit and the second end of the sixth resistor, respectively. The IN pin of the second analog switch chip is connected to the central processing unit.

[0012] Optionally, the resistance values ​​of the sixth, seventh, eighth, ninth, tenth, and eleventh resistors are all 100Ω.

[0013] Optionally, the fourth resistor has a resistance of 15kΩ and the fifth resistor has a resistance of 2kΩ.

[0014] Optionally, the central processing unit includes a current and voltage sampling circuit, a switching control circuit, and a fuzzy PI control circuit;

[0015] Current and voltage sampling circuits are used to acquire data from the output voltage sampling circuit and the output current sampling circuit;

[0016] Switching control circuit, used to control the switching quantities of power factor correction circuit, phase-shifted full-bridge circuit, current range sampling circuit and voltage range sampling circuit;

[0017] A fuzzy PI control circuit is used to track the inherent characteristic frequency of an ultrasonic vibration system based on the phase angle of the ultrasonic transducer using a fuzzy PI control algorithm.

[0018] The feedback branch of the fuzzy PI control circuit includes a phase measurement circuit and a bandpass filter. The input of the bandpass filter is connected to the output of the ultrasonic transducer, the output of the bandpass filter is connected to the input of the phase measurement circuit, and the output of the phase measurement circuit is connected to the comparator.

[0019] Optionally, the bandpass filter is a fourth-order Butterworth bandpass filter.

[0020] Optionally, the phase-shifted full-bridge circuit includes a first IGBT, a second IGBT, a third IGBT, a fourth IGBT, a first diode, a second diode, a third diode, a fourth diode, a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor;

[0021] The collector of the first IGBT, the cathode of the first diode, one end of the first capacitor, the collector of the third IGBT, and one end of the third capacitor are connected to the output of the power factor correction circuit.

[0022] The gates of the first, second, third, and fourth IGBT transistors are left floating.

[0023] The emitter of the first IGBT is connected to the collector of the second IGBT, the other end of the first capacitor and the anode of the first diode are connected to the emitter of the first IGBT, the emitter of the third IGBT is connected to the collector of the fourth IGBT, and the other end of the third capacitor and the anode of the third diode are connected to the emitter of the fourth IGBT.

[0024] One end of the second capacitor and the positive terminal of the second diode are connected to the collector of the second IGBT, and the other end of the second capacitor and the positive terminal of the second diode are connected to the emitter of the second IGBT.

[0025] One end of the fourth capacitor and the negative terminal of the fourth diode are connected to the collector of the fourth IGBT, and the other end of the fourth capacitor and the positive terminal of the fourth diode are connected to the emitter of the fourth IGBT.

[0026] The emitters of the second and fourth IGBTs are grounded.

[0027] Optionally, the tuning circuit includes a first inductor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, and a ninth capacitor;

[0028] The fifth, sixth, seventh, eighth, and ninth capacitors are connected in series.

[0029] The first terminal of the first inductor is connected to the first output terminal of the transformer isolation circuit, the second terminal is connected to the fifth capacitor, and the ninth capacitor is connected to the second output terminal of the transformer isolation circuit.

[0030] Optionally, the transformer isolation circuit includes a transformer, a tenth capacitor, an eleventh capacitor, a twelfth capacitor, and a thirteenth capacitor;

[0031] After the tenth, eleventh, twelfth, and thirteenth capacitors are connected in parallel, the first parallel terminal is connected between the third and fourth IGBT transistors of the phase-shifted full-bridge circuit, the second parallel terminal is connected to one input terminal of the transformer, and the other input terminal of the transformer is connected to the emitter of the first IGBT transistor.

[0032] Optionally, it also includes overcurrent protection circuit and overvoltage protection circuit;

[0033] The overcurrent protection circuit and the overvoltage protection circuit are respectively connected to the central processing unit and are used to provide overcurrent protection and overvoltage protection for the output current and output voltage of the ultrasonic power supply circuit.

[0034] Optionally, the power factor correction circuit includes a second inductor, a fifth IGBT, a sixth IGBT, a fifth diode, a sixth diode, a first electrolytic capacitor, and a second electrolytic capacitor;

[0035] One end of the second inductor is connected to the rectifier filter circuit, and the other end is connected to the common terminal of the fifth IGBT and the sixth IGBT. The emitter of the fifth IGBT is grounded, the collector of the sixth IGBT is connected to the collector of the fifth IGBT, the emitter of the sixth IGBT is connected to the positive terminal of the first electrolytic capacitor and the phase-shifted full-bridge circuit, the negative terminal of the first electrolytic capacitor is grounded, and the second electrolytic capacitor is connected in parallel with the first electrolytic capacitor.

[0036] The negative terminal of the fifth diode is connected to the collector of the fifth IGBT, and the positive terminal is connected to the emitter of the fifth IGBT.

[0037] The negative terminal of the sixth diode is connected to the collector of the sixth IGBT, and the positive terminal is connected to the emitter of the sixth IGBT.

[0038] The gates of the fifth and sixth IGBTs are left floating.

[0039] Optionally, the rectifier filter circuit includes a bridge rectifier circuit, a third electrolytic capacitor, and a fourth electrolytic capacitor;

[0040] A third electrolytic capacitor is connected between the positive and negative terminals of the DC output of the bridge rectifier circuit.

[0041] The positive terminal of the third electrolytic capacitor is connected to the input terminal of the power factor correction circuit, and the negative terminal is grounded.

[0042] The fourth electrolytic capacitor is connected in parallel with the third electrolytic capacitor;

[0043] The positive and negative terminals of the AC input of a bridge rectifier circuit are connected to the positive and negative terminals of the mains power.

[0044] Optionally, the phase-shifted full-bridge circuit is connected to the central processing unit via an optocoupler isolation circuit.

[0045] As can be seen from the above technical solutions, the ultrasonic power supply circuit provided by the present invention has the following advantages:

[0046] The ultrasonic power supply circuit provided by this invention includes a rectifier and filter circuit, a power factor correction circuit, a phase-shifted full-bridge circuit, a transformer isolation circuit, a tuning circuit, an output voltage sampling circuit, an output current sampling circuit, a current-scaled sampling circuit, a voltage-scaled sampling circuit, and a central processing unit connected in sequence. The central processing unit obtains the output voltage and output current of the ultrasonic power supply circuit through the output voltage sampling circuit and the output current sampling circuit, respectively. Based on the output voltage and output current, it determines the circuit configuration of the current-scaled sampling circuit and the voltage-scaled sampling circuit. When the output voltage is not greater than 200V, a sampling resistor branch composed of a first resistor, a second resistor, a third resistor, and a fourth resistor can be used. Voltage sampling is performed using a sampling resistor branch consisting of the first, second, third, and fifth resistors when the output voltage is greater than 200V. Then, a fuzzy PI control algorithm is used to track the inherent characteristic frequency of the ultrasonic vibration system, which can output a stable ultrasonic drive signal. This ensures that the changes in the inherent characteristic frequency of the ultrasonic vibration system can be accurately tracked. This solves the technical problem that existing ultrasonic power supply frequency tracking methods cannot simultaneously ensure the accuracy of voltage sampling from 20V to 1500V, and it is difficult to ensure that the frequency of the ultrasonic power output from the ultrasonic power supply follows the changes in the inherent characteristic frequency of the ultrasonic vibration system in real time, resulting in low frequency tracking accuracy.

[0047] Meanwhile, the ultrasonic power supply circuit provided by the present invention is also equipped with a current grading sampling circuit. When the output current is greater than 5A, the current is sampled using a resistor branch composed of the seventh, eighth, ninth, tenth and eleventh resistors. When the output current is not greater than 5A, the sixth resistor is used for current sampling, thus realizing the function of current grading sampling and improving the accuracy of current sampling.

[0048] Ultrasonic power supplies are essentially digital switching power supplies, containing numerous MOSFETs or IGBTs. These switches generate high-frequency electromagnetic interference during operation. Frequency tracking in ultrasonic power supplies is achieved by locking the phase angle between voltage and current. This phase angle is detected by converting the voltage and current waveforms into square waves using a zero-crossing comparator circuit. Switching noise can cause the voltage and current sampling signals to oscillate near zero, leading to inaccurate phase detection. Therefore, the ultrasonic power supply circuit provided in this invention incorporates a bandpass filter when using a fuzzy PI control algorithm to track the inherent characteristic frequency of the ultrasonic vibration system. This filter removes switching noise from the original current and voltage sampling signals, preventing the switching noise from causing oscillations near zero and resulting in inaccurate phase detection.

[0049] The ultrasonic power supply circuit provided by the present invention is further provided with an overcurrent protection circuit and an overvoltage protection circuit, which can provide overcurrent protection and overvoltage protection for the output current and output voltage of the ultrasonic power supply circuit. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a schematic diagram of a modular structure of an ultrasonic power supply circuit provided in this invention.

[0052] Figure 2 This is a schematic diagram of a current-grading sampling circuit for an ultrasonic power supply circuit provided in this invention.

[0053] Figure 3 This is a schematic diagram of a voltage-grading sampling circuit for an ultrasonic power supply circuit provided in this invention.

[0054] Figure 4 This is a schematic diagram of a fuzzy PI control circuit for an ultrasonic power supply circuit provided in this invention.

[0055] Figure 5 This is a schematic diagram of the circuit structure of the bandpass filter provided in this invention. Detailed Implementation

[0056] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] For easier understanding, please refer to Figures 1 to 2 The present invention provides an embodiment of an ultrasonic power supply circuit, including a rectifier filter circuit, a power factor correction circuit, a phase-shifted full-bridge circuit, a transformer isolation circuit and a tuning circuit connected in sequence, and also includes an output voltage sampling circuit, an output current sampling circuit, a current grading sampling circuit and a voltage grading sampling circuit.

[0058] The power factor correction circuit, phase-shifted full-bridge circuit, output voltage sampling circuit, output current sampling circuit, current range sampling circuit, and voltage range sampling circuit are all connected to the central processing unit.

[0059] The voltage grading sampling circuit includes a first analog switch chip U2, a first resistor R7, a second resistor R8, a third resistor R9, a fourth resistor R10, and a fifth resistor R11. The first end of the fifth resistor R11 is connected to the NO pin of the first analog switch chip U1, and the second end is connected to the first end of the third resistor R9. The first end of the fourth resistor R10 is connected to the NC pin of the first analog switch chip U1, and the second end is connected to the first end of the third resistor R9. The first resistor R7, the second resistor R8, and the third resistor R9 are connected in series. The first resistor R7 is connected to the current transformer CT1 of the output current sampling circuit. The IN pin of the first analog switch chip U1 is connected to the central processing unit.

[0060] The central processing unit is used to acquire data from the output voltage sampling circuit and the output current sampling circuit, and to control the power factor correction circuit, the phase-shifting full-bridge circuit, the current-grading sampling circuit, and the voltage-grading sampling circuit. Based on the phase angle of the ultrasonic transducer, a fuzzy PI control algorithm is used to track the inherent characteristic frequency of the ultrasonic vibration system.

[0061] It should be noted that the ultrasonic power supply circuit provided by this invention is as follows: Figure 1 As shown, it includes a rectifier filter circuit, a power factor correction circuit, a phase-shifted full-bridge circuit, a transformer isolation circuit, and a tuning circuit connected in sequence, and an output voltage sampling circuit, an output current sampling circuit, a current range sampling circuit, and a voltage range sampling circuit. The power factor correction circuit, the phase-shifted full-bridge circuit, the output voltage sampling circuit, the output current sampling circuit, the current range sampling circuit, and the voltage range sampling circuit are respectively connected to the central processing unit.

[0062] in:

[0063] A rectifier and filter circuit is used to rectify the input AC power into DC power.

[0064] Power factor correction circuits are used to reduce harmonic current pollution and perform reactive power compensation on-site, ensuring that power fluctuations do not affect the stability of the load.

[0065] A phase-shifting full-bridge circuit is used to invert AC power at ultrasonic frequencies with controllable voltage and current.

[0066] The transformer isolation circuit transforms the impedance of the ultrasonic vibration system into an equivalent impedance equal to the internal resistance of the ultrasonic power supply, ensuring maximum energy transmission efficiency and providing electrical isolation between input and output, thus guaranteeing the electrical safety of the ultrasonic vibration system. Simultaneously, the transformer isolation circuit isolates the DC component in the phase-shifted full-bridge circuit.

[0067] The tuning circuit is used for low-pass filtering and tuning, filtering out high-frequency components from the square wave output by the phase-shifted full-bridge circuit to obtain the fundamental sinusoidal signal of the ultrasonic frequency. Simultaneously, the tuning circuit also functions to form a series resonance with the capacitors in the ultrasonic vibration system, thereby ensuring the maximum ultrasonic amplitude output by the ultrasonic vibration system.

[0068] The output voltage sampling circuit is used to collect the output voltage of the ultrasonic power supply circuit, and after conditioning, the output voltage is provided to the central processing unit for processing.

[0069] The output current sampling circuit is used to collect the output current of the ultrasonic power supply circuit, and after conditioning, the output current is provided to the central processing unit for processing.

[0070] The voltage-gradient sampling circuit is used to sample voltage using a sampling resistor branch consisting of resistors 1, 2, 3, and 4 when the output voltage is no greater than 200V; when the output voltage is greater than 200V, it uses the same branch; and when the output current is greater than 5A, it uses a branch consisting of resistors 7, 8, 9, 10, and 11. By selecting different sampling resistors according to the voltage magnitude, the sampled signal is always kept within a clearly distinguishable range, thus ensuring the validity of the original sampled signal.

[0071] The central processing unit (CPU) includes a current and voltage sampling circuit, a switching control circuit, and a fuzzy PI control circuit. The current and voltage sampling circuit acquires data from the output voltage and current sampling circuits. The switching control circuit controls the switching quantities of the power factor correction circuit, the phase-shifted full-bridge circuit, the current-scaled sampling circuit, and the voltage-scaled sampling circuit. The phase-shifted full-bridge circuit is connected to the CPU via an optocoupler isolation circuit for photoelectric isolation. The fuzzy PI control circuit uses a fuzzy PI control algorithm to track the inherent characteristic frequency of the ultrasonic vibration system based on the phase angle of the ultrasonic transducer. The feedback branch of the fuzzy PI control circuit includes a phase measurement circuit and a bandpass filter. The input of the bandpass filter is connected to the output of the ultrasonic transducer, and the output of the bandpass filter is connected to the input of the phase measurement circuit. The output of the phase measurement circuit is connected to a comparator. Figure 4 As shown, the principle of the fuzzy PI control circuit in this invention is as follows: the phase angle θ of the transducer is measured by the phase measurement circuit, and the difference between it and the actual target phase angle goal_θ is calculated. The difference E is used as the judgment basis. The error E and the error change rate Ec (i.e., de / dt) are used as the input of the fuzzy controller. The outputs of the fuzzy controller ΔKp and ΔKi are used as the incremental expressions of the PI controller Kp and Ki, and are input to the PI controller to adjust the proportional coefficient Kp and integral coefficient Ki to obtain a better control effect.

[0072] Specifically, the fourth resistor R10 has a resistance of 15kΩ, and the fifth resistor R11 has a resistance of 2kΩ.

[0073] In one embodiment, the ultrasonic power supply circuit provided by the present invention further includes a current-grading sampling circuit, such as... Figure 3 As shown, the current grading sampling circuit includes a second analog switch chip U1, a sixth resistor R1, a seventh resistor R2, an eighth resistor R3, a ninth resistor R4, a tenth resistor R5, and an eleventh resistor R6. The first terminal of the sixth resistor R1 is connected to the NC pin of the second analog switch chip U1, and the second terminal is connected to the current transformer CT1 of the output current sampling circuit. The first terminal of the seventh resistor R2, the eighth resistor R3, the ninth resistor R4, the tenth resistor R5, and the eleventh resistor R6 connected in parallel is connected to the NO pin of the second analog switch chip U1, and the second terminal is connected to the output current sampling circuit and the second terminal of the sixth resistor R2, respectively. The IN pin of the second analog switch chip U1 is connected to the central processing unit. The resistance values ​​of the sixth resistor R1, the seventh resistor R2, the eighth resistor R3, the ninth resistor R4, the tenth resistor R5, and the eleventh resistor R6 are all 100Ω.

[0074] Specifically, the specific circuit structure of the ultrasonic power supply circuit provided in this invention is as follows:

[0075] The rectifier and filter circuit consists of a bridge rectifier circuit, a third electrolytic capacitor, and a fourth electrolytic capacitor. The third electrolytic capacitor is connected between the positive and negative terminals of the DC output terminal of the bridge rectifier circuit. The positive terminal of the third electrolytic capacitor is connected to the input terminal of the power factor correction circuit, and the negative terminal is grounded. The fourth electrolytic capacitor is connected in parallel with the third electrolytic capacitor. The positive and negative terminals of the AC input terminal of the bridge rectifier circuit are connected to the positive and negative terminals of the mains power.

[0076] The power factor correction circuit includes a second inductor, a fifth IGBT, a sixth IGBT, a fifth diode, a sixth diode, a first electrolytic capacitor, and a second electrolytic capacitor. One end of the second inductor is connected to the rectifier filter circuit, and the other end is connected to the common terminal of the fifth and sixth IGBTs. The emitter of the fifth IGBT is grounded, and the collector of the sixth IGBT is connected to the collector of the fifth IGBT. The emitter of the sixth IGBT is connected to the positive terminal of the first electrolytic capacitor and the phase-shifting full-bridge circuit. The negative terminal of the first electrolytic capacitor is grounded. The second electrolytic capacitor is connected in parallel with the first electrolytic capacitor. The negative terminal of the fifth diode is connected to the collector of the fifth IGBT, and the positive terminal is connected to the emitter of the fifth IGBT. The negative terminal of the sixth diode is connected to the collector of the sixth IGBT, and the positive terminal is connected to the emitter of the sixth IGBT. The gates of the fifth and sixth IGBTs are left floating.

[0077] The phase-shifted full-bridge circuit includes a first IGBT, a second IGBT, a third IGBT, a fourth IGBT, a first diode, a second diode, a third diode, a fourth diode, a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor. The collector of the first IGBT, the cathode of the first diode, one end of the first capacitor, the collector of the third IGBT, and one end of the third capacitor are connected to the output of the power factor correction circuit. The gates of the first, second, third, and fourth IGBTs are floating. The emitter of the first IGBT is connected to the collector of the second IGBT. The other end of the first capacitor is connected to the cathode of the first diode. The third IGBT is connected to the emitter of the first IGBT, the emitter of the third IGBT is connected to the collector of the fourth IGBT, the other end of the third capacitor and the anode of the third diode are connected to the emitter of the fourth IGBT, one end of the second capacitor and the anode of the second diode are connected to the collector of the second IGBT, the other end of the second capacitor and the anode of the second diode are connected to the emitter of the second IGBT, one end of the fourth capacitor and the cathode of the fourth diode are connected to the collector of the fourth IGBT, the other end of the fourth capacitor and the anode of the fourth diode are connected to the emitter of the fourth IGBT, and the emitters of the second and fourth IGBTs are grounded.

[0078] The transformer isolation circuit includes a transformer, a tenth capacitor, an eleventh capacitor, a twelfth capacitor, and a thirteenth capacitor. These capacitors are connected in parallel. The first parallel connection terminal is connected between the third and fourth IGBT transistors in the phase-shifted full-bridge circuit. The second parallel connection terminal is connected to one input terminal of the transformer, and the other input terminal of the transformer is connected to the emitter of the first IGBT transistor. The tenth, eleventh, twelfth, and thirteenth capacitors constitute a DC component isolation circuit, used to isolate the DC component in the inverter circuit.

[0079] The tuning circuit includes a first inductor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, and a ninth capacitor, which are connected in series. The first terminal of the first inductor is connected to the first output terminal of the transformer isolation circuit, and the second terminal is connected to the fifth capacitor. The ninth capacitor is connected to the second output terminal of the transformer isolation circuit.

[0080] The output current sampling circuit consists of a current transformer CT1 and its peripheral circuits. Its function is to collect the output current, condition the output current to a suitable value, and provide it to the central processing unit for calculation.

[0081] The output voltage sampling circuit consists of a voltage sampling chip and its peripheral circuits, forming voltage sampling circuits for each stage of the circuit. Its function is to collect the output voltage, condition the output voltage to a suitable value, and provide it to the central processing unit for calculation.

[0082] In one embodiment, such as Figure 5 As shown, the bandpass filter of the fuzzy PI control circuit in this invention is a fourth-order Butterworth bandpass filter. The passband ripple is set to 3dB, the center frequency to 20kHz, and the passband bandwidth to 6kHz. The calculated stopband attenuation is -40dB, the number of stages is 2, the maximum Q value is 4.741, the stopband bandwidth is 60kHz, and the gain is 3.162V / V. This bandpass filter can effectively filter out the switching noise of the switching transistor.

[0083] The ultrasonic power supply circuit provided in this invention also includes an overcurrent protection circuit and an overvoltage protection circuit, which are respectively connected to the central processing unit and are used to provide overcurrent and overvoltage protection for the output current and output voltage of the ultrasonic power supply circuit. The final output current and voltage of the ultrasonic power supply circuit are compared with its set protection values. When the set protection value is exceeded, a protection action is triggered to stop the ultrasonic output, thereby ensuring the safety of the power supply and load under abnormal conditions.

[0084] Compared with the prior art, the ultrasonic power supply circuit provided by the present invention includes a rectifier filter circuit, a power factor correction circuit, a phase-shifted full-bridge circuit, a transformer isolation circuit, a tuning circuit, an output voltage sampling circuit, an output current sampling circuit, a current-scaled sampling circuit, a voltage-scaled sampling circuit, and a central processing unit connected in sequence. The central processing unit obtains the output voltage and output current of the ultrasonic power supply circuit through the output voltage sampling circuit and the output current sampling circuit, respectively, and determines the circuit configuration of the current-scaled sampling circuit and the voltage-scaled sampling circuit based on the output voltage and output current. When the output voltage is not greater than 200V, a sampling resistor composed of a first resistor, a second resistor, a third resistor, and a fourth resistor can be used. The branch performs voltage sampling. When the output voltage is greater than 200V, the sampling resistor branch composed of the first, second, third, and fifth resistors is used to sample the voltage. Then, the fuzzy PI control algorithm is used to track the inherent characteristic frequency of the ultrasonic vibration system, which can output a stable ultrasonic drive signal. This ensures that the changes in the inherent characteristic frequency of the ultrasonic vibration system can be accurately tracked. This solves the technical problem that the existing ultrasonic power supply frequency tracking method cannot simultaneously ensure the accuracy of voltage sampling from 20V to 1500V, and it is difficult to ensure that the frequency of the ultrasonic power output from the ultrasonic power supply follows the changes in the inherent characteristic frequency of the ultrasonic vibration system in real time, resulting in low frequency tracking accuracy.

[0085] Meanwhile, the ultrasonic power supply circuit provided by the present invention is also equipped with a current grading sampling circuit. When the output current is greater than 5A, the current is sampled using a resistor branch composed of the seventh, eighth, ninth, tenth and eleventh resistors. When the output current is not greater than 5A, the sixth resistor is used for current sampling, thus realizing the function of current grading sampling and improving the accuracy of current sampling.

[0086] Ultrasonic power supplies are essentially digital switching power supplies, containing numerous MOSFETs or IGBTs. These switches generate high-frequency electromagnetic interference during operation. Frequency tracking in ultrasonic power supplies is achieved by locking the phase angle between voltage and current. This phase angle is detected by converting the voltage and current waveforms into square waves using a zero-crossing comparator circuit. Switching noise can cause the voltage and current sampling signals to oscillate near zero, leading to inaccurate phase detection. Therefore, the ultrasonic power supply circuit provided in this invention incorporates a bandpass filter when using a fuzzy PI control algorithm to track the inherent characteristic frequency of the ultrasonic vibration system. This filter removes switching noise from the original current and voltage sampling signals, preventing the switching noise from causing oscillations near zero and resulting in inaccurate phase detection.

[0087] The ultrasonic power supply circuit provided by the present invention is further provided with an overcurrent protection circuit and an overvoltage protection circuit, which can provide overcurrent protection and overvoltage protection for the output current and output voltage of the ultrasonic power supply circuit.

[0088] The terms "first," "second," "third," "fourth," etc., used in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0089] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ultrasonic power supply circuit, characterized in that, It includes a rectifier filter circuit, a power factor correction circuit, a phase-shifted full-bridge circuit, a transformer isolation circuit, and a tuning circuit connected in sequence, as well as an output voltage sampling circuit, an output current sampling circuit, and a voltage range sampling circuit. The power factor correction circuit, phase-shifted full-bridge circuit, output voltage sampling circuit, output current sampling circuit, and voltage grading sampling circuit are all connected to the central processing unit. The voltage grading sampling circuit includes a first analog switch chip, a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor. The first end of the fifth resistor is connected to the NO pin of the first analog switch chip, and the second end is connected to the first end of the third resistor. The first end of the fourth resistor is connected to the NC pin of the first analog switch chip, and the second end is connected to the first end of the third resistor. The first, second, and third resistors are connected in series. The first resistor is connected to the current transformer of the output current sampling circuit, and the IN pin of the first analog switch chip is connected to the central processing unit. The central processing unit is used to acquire data from the output voltage sampling circuit and the output current sampling circuit, and to control the power factor correction circuit, the phase-shifting full-bridge circuit and the voltage grading sampling circuit. Based on the phase angle of the ultrasonic transducer, a fuzzy PI control algorithm is used to track the inherent characteristic frequency of the ultrasonic vibration system. The central processing unit includes a fuzzy PI control circuit and a feedback branch of the fuzzy PI control circuit; A fuzzy PI control circuit is used to track the inherent characteristic frequency of an ultrasonic vibration system based on the phase angle of the ultrasonic transducer using a fuzzy PI control algorithm. The feedback branch of the fuzzy PI control circuit includes a phase measurement circuit and a bandpass filter. The input of the bandpass filter is connected to the output of the ultrasonic transducer, the output of the bandpass filter is connected to the input of the phase measurement circuit, and the output of the phase measurement circuit is connected to the comparator.

2. The ultrasonic power supply circuit according to claim 1, characterized in that, It also includes a current-grading sampling circuit; The current grading sampling circuit is connected to the central processing unit; The current grading sampling circuit includes a second analog switch chip, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, and an eleventh resistor. The first end of the sixth resistor is connected to the NC pin of the second analog switch chip, and the second end is connected to the current transformer of the output current sampling circuit. The first end of the seventh, eighth, ninth, tenth, and eleventh resistors connected in parallel is connected to the NO pin of the second analog switch chip, and the second end is connected to the output current sampling circuit and the second end of the sixth resistor, respectively. The IN pin of the second analog switch chip is connected to the central processing unit.

3. The ultrasonic power supply circuit according to claim 2, characterized in that, The resistance values ​​of the sixth, seventh, eighth, ninth, tenth, and eleventh resistors are all 100Ω.

4. The ultrasonic power supply circuit according to claim 1, characterized in that, The fourth resistor has a resistance of 15kΩ, and the fifth resistor has a resistance of 2kΩ.

5. The ultrasonic power supply circuit according to claim 2, characterized in that, The central processing unit also includes current and voltage sampling circuits and switching control circuits; Current and voltage sampling circuits are used to acquire data from the output voltage sampling circuit and the output current sampling circuit; The switching control circuit is used to control the switching quantities of the power factor correction circuit, the phase-shifted full-bridge circuit, the current-scale sampling circuit, and the voltage-scale sampling circuit.

6. The ultrasonic power supply circuit according to claim 5, characterized in that, The bandpass filter is a fourth-order Butterworth type bandpass filter.

7. The ultrasonic power supply circuit according to claim 1, characterized in that, The phase-shifted full-bridge circuit includes a first IGBT, a second IGBT, a third IGBT, a fourth IGBT, a first diode, a second diode, a third diode, a fourth diode, a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor; The collector of the first IGBT, the cathode of the first diode, one end of the first capacitor, the collector of the third IGBT, and one end of the third capacitor are connected to the output of the power factor correction circuit. The gates of the first, second, third, and fourth IGBT transistors are left floating. The emitter of the first IGBT is connected to the collector of the second IGBT, the other end of the first capacitor and the anode of the first diode are connected to the emitter of the first IGBT, the emitter of the third IGBT is connected to the collector of the fourth IGBT, and the other end of the third capacitor and the anode of the third diode are connected to the emitter of the fourth IGBT. One end of the second capacitor and the positive terminal of the second diode are connected to the collector of the second IGBT, and the other end of the second capacitor and the positive terminal of the second diode are connected to the emitter of the second IGBT. One end of the fourth capacitor and the negative terminal of the fourth diode are connected to the collector of the fourth IGBT, and the other end of the fourth capacitor and the positive terminal of the fourth diode are connected to the emitter of the fourth IGBT. The emitters of the second and fourth IGBTs are grounded.

8. The ultrasonic power supply circuit according to claim 7, characterized in that, The tuning circuit includes a first inductor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, and a ninth capacitor; The fifth, sixth, seventh, eighth, and ninth capacitors are connected in series. The first terminal of the first inductor is connected to the first output terminal of the transformer isolation circuit, the second terminal is connected to the fifth capacitor, and the ninth capacitor is connected to the second output terminal of the transformer isolation circuit.

9. The ultrasonic power supply circuit according to claim 8, characterized in that, The transformer isolation circuit includes a transformer, a tenth capacitor, an eleventh capacitor, a twelfth capacitor, and a thirteenth capacitor; After the tenth, eleventh, twelfth, and thirteenth capacitors are connected in parallel, the first parallel terminal is connected between the third and fourth IGBT transistors of the phase-shifted full-bridge circuit, the second parallel terminal is connected to one input terminal of the transformer, and the other input terminal of the transformer is connected to the emitter of the first IGBT transistor.

10. The ultrasonic power supply circuit according to claim 1, characterized in that, It also includes overcurrent protection circuits and overvoltage protection circuits; The overcurrent protection circuit and the overvoltage protection circuit are connected to the central processing unit respectively, and are used to provide overcurrent protection and overvoltage protection for the output current and output voltage of the ultrasonic power supply circuit.

Images