An automatic frequency tracking circuit and frequency tracking method for power supply of ultrasonic cleaning machine

Abstract

The present invention discloses an automatic frequency tracking circuit for the power supply of an ultrasonic cleaner, which includes an output control module and an input sampling module. The output control module includes an EMI circuit, a rectification circuit, a full-bridge phase-shifting circuit, a matching circuit, and a DSP main control chip. The input sampling module includes a sampling circuit, a phase detection circuit, a root-mean-square current calculation circuit, and a DSP main control chip. A frequency tracking method for an automatic frequency tracking circuit of the power supply of an ultrasonic cleaner includes the following steps: S1. The ultrasonic power supply outputs from the minimum frequency to the maximum frequency at a certain step size in sequence to form a response curve; S2. When the difference Δ Imax of the current peak value in this cycle is smaller than that in the previous cycle, the output frequency value of the next cycle is made closer to that of the previous cycle; otherwise, the output frequency value of the next cycle is made farther away from the frequency value of the previous cycle, and this is repeated. The advantages of the present invention are: improving the conversion efficiency of the power supply of the cleaner, automatically and real-time tracking the optimal working frequency, and ensuring the cleaning effect.

Description

Technical Field

[0001] The invention relates to the technical field of automatic power frequency tracking, and in particular to an automatic power frequency tracking circuit for an ultrasonic cleaning machine and a frequency tracking method thereof. Background Art

[0002] The optimal operating frequency of an ultrasonic cleaning machine varies with the temperature of the cleaning fluid, the depth of the cleaning fluid, and the size of the workpiece being cleaned. In order to achieve the best cleaning effect, the ultrasonic power supply needs to be able to automatically and real-time track the frequency of the cleaning machine.

[0003] At present, the common practice is to track the frequency point corresponding to the maximum current of the ultrasonic power supply in real time. For example, the digital ultrasonic generator of patent CN200720119112.4 adopts the maximum current method to track the frequency. The active current corresponding to the maximum current is not necessarily the largest, the conversion efficiency is low, and the cleaning effect is not optimal.

[0004] This frequency tracking method has the following disadvantages: the reactive component of the output is large and the power conversion efficiency is low; the larger the output current peak value, the better the cleaning effect is not necessarily. On the contrary, excessive peak current will damage the life of the ultrasonic vibrator. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an automatic frequency tracking circuit and a frequency tracking method for an ultrasonic cleaning machine power supply, which can improve the conversion efficiency of the cleaning machine power supply, automatically track the optimal operating frequency in real time, and ensure the cleaning effect.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is: an automatic frequency tracking circuit of an ultrasonic cleaning machine power supply, comprising an output control module and an input sampling module, the output control module comprising an EMI circuit, a rectifier circuit, a full-bridge phase shift circuit, a matching circuit and a DSP main control chip, the EMI circuit is signal-connected to the rectifier circuit, the rectifier circuit is signal-connected to the full-bridge phase shift circuit, the full-bridge phase shift circuit is signal-connected to the matching circuit, the full-bridge phase shift circuit is signal-connected to the DSP main control chip, the input sampling module comprises a sampling circuit, a phase detection circuit, a current effective value calculation circuit and a DSP main control chip, the sampling circuit is signal-connected to the phase detection circuit, the phase detection circuit is signal-connected to the current effective value calculation circuit, the phase detection circuit and the current effective value calculation circuit are signal-connected to the DSP main control chip, the DSP main control chip is signal-connected with a start-stop button, the EMI circuit is electrically connected to the power supply, and the output control module and the input sampling module constitute a real-time closed-loop feedback system when working.

[0007] Furthermore, the power supply passes through the EMI circuit, and the X1 capacitor, common mode inductor L1 and Y capacitors Y1 and Y2 in the EMI circuit perform anti-interference processing, and the rectifier diodes D1, D2, D3 and D4 in the rectifier circuit perform full-wave rectification, and C1 in the rectifier circuit filters the rectified voltage into pulsating direct current, and then outputs it to the full-bridge phase-shift circuit. The IGBTs G1, G2, G3 and G4 in the full-bridge phase-shift circuit invert and amplify the pulsating direct current according to the frequency output by the DSP main control chip, and then output it to the primary side of the transformer T1 in the matching circuit. The transformer T1 transfers the energy of the primary side to the series resonant circuit composed of the inductor L2 and the transducer, completing an energy transfer.

[0008] Furthermore, when the full-bridge phase-shift circuit inverts and amplifies the energy flowing through it and transfers it out through the transformer T1, a voltage V and a current C are generated on the output loop of the full-bridge phase-shift circuit. The voltage transformer CT1 and the current transformer CT2 in the sampling circuit will induce voltage signals of the same proportion. After being conditioned by the operational amplifiers U1A and U1B, the voltage transformer CT1 is sent to the phase detection circuit and the current effective value circuit respectively. The logic chips U2A, U2B and the D-flip-flop chips U3A, U3B in the phase detection circuit separate the phase advance and lag between the current signal and the voltage signal, and send them to the operational amplifier U3. U3 converts the phase difference into a voltage signal and sends it to the DSP main control chip for processing. U4 in the current effective value circuit converts the conditioned current signal into a voltage value corresponding to the current RMS value, and sends it to the DSP main control chip for processing.

[0009] Furthermore, the sampling circuit and the phase detection circuit detect the phase difference Φ, the sampling circuit and the current effective value circuit detect the apparent current, and the DSP main control chip calculates the frequency interval corresponding to the maximum active current, and the calculation formula is Iactive=Iapparent*cosΦ, and the difference of the current peak value within one cycle in this interval is Δ Imax is used as the criterion for automatic frequency tracking.

[0010] A frequency tracking method for an automatic frequency tracking circuit of an ultrasonic cleaning machine power supply comprises the following steps:

[0011] S1, the ultrasonic power supply outputs from the minimum frequency to the maximum frequency in a certain step distance, evaluates the load, and continuously collects the active current during the process to form a frequency-active current response curve;

[0012] S2. After the load evaluation is completed, the frequency tracking method is started in the frequency range corresponding to the maximum active current, that is, the difference of the current peak value is calculated in each fixed large cycle Δ Imax, and the difference between the peak current of the previous large cycle ΔImax is compared. When the difference of the current peak value of this cycle is smaller than that of the previous cycle, the output frequency value of the next cycle is brought closer to the frequency value of the previous cycle; otherwise, the output frequency value of the next cycle is moved away from the frequency value of the previous cycle, and this process is repeated.

[0013] Compared with the prior art, the invention has the advantages that the automatic frequency tracking circuit and frequency tracking method of the ultrasonic cleaning machine power supply are based on the difference of the current peak value output by the ultrasonic power supply within a unit cycle. Δ Imax is used as the basis for real-time frequency tracking. When the temperature rises with the cleaning time and the load of the cleaning machine changes, it can ensure the best cleaning effect; at the same time, it improves the conversion efficiency of the power supply and ensures the service life of the ultrasonic vibrator. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention is a circuit schematic diagram of an automatic frequency tracking circuit for an ultrasonic cleaning machine power supply.

[0015] Figure 2 The present invention is a flow chart of a frequency tracking method of an automatic frequency tracking circuit for an ultrasonic cleaning machine power supply. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0017] As shown in the figure, an automatic frequency tracking circuit for power supply of an ultrasonic cleaning machine includes an output control module and an input sampling module. The output control module includes an EMI circuit, a rectifier circuit, a full-bridge phase shift circuit, a matching circuit and a DSP main control chip. The EMI circuit is signal-connected to the rectifier circuit, the rectifier circuit is signal-connected to the full-bridge phase shift circuit, the full-bridge phase shift circuit is signal-connected to the matching circuit, the full-bridge phase shift circuit is signal-connected to the DSP main control chip, the input sampling module includes a sampling circuit, a phase detection circuit, a current effective value calculation circuit and a DSP main control chip, the sampling circuit is signal-connected to the phase detection circuit, the phase detection circuit is signal-connected to the current effective value calculation circuit, the phase detection circuit and the current effective value calculation circuit are signal-connected to the DSP main control chip, the DSP main control chip is signal-connected with a start-stop button, the EMI circuit is electrically connected to the power supply, and the output control module and the input sampling module form a real-time closed-loop feedback system when working.

[0018] The power supply passes through the EMI circuit, and the X1 capacitor, common mode inductor L1 and Y capacitors Y1 and Y2 in the EMI circuit perform anti-interference processing. The rectifier diodes D1, D2, D3 and D4 in the rectifier circuit perform full-wave rectification. C1 in the rectifier circuit filters the rectified voltage into pulsating direct current, and then outputs it to the full-bridge phase-shift circuit. The IGBTs G1, G2, G3 and G4 in the full-bridge phase-shift circuit invert and amplify the pulsating direct current according to the frequency output by the DSP main control chip, and then output it to the primary side of the transformer T1 in the matching circuit. The transformer T1 transfers the energy of the primary side to the series resonant circuit composed of the inductor L2 and the transducer, completing an energy transfer.

[0019] When the full-bridge phase-shift circuit inverts and amplifies the energy flowing through it and transfers it out through the transformer T1, a voltage V and a current C are generated on the output loop of the full-bridge phase-shift circuit. The voltage transformer CT1 and the current transformer CT2 in the sampling circuit will induce voltage signals of the same proportion, which are sent to the phase detection circuit and the current effective value circuit respectively after being conditioned by the U1A and U1B operational amplifiers. The logic chips U2A, U2B and the D-type flip-flop chips U3A, U3B in the phase detection circuit separate the phase advance and lag between the current signal and the voltage signal, and send them to the operational amplifier U3. U3 converts the phase difference into a voltage signal and sends it to the DSP main control chip for processing. U4 in the current effective value circuit converts the conditioned current signal into a voltage value corresponding to the current RMS value, and sends it to the DSP main control chip for processing.

[0020] The sampling circuit and the phase detection circuit detect the phase difference Φ, the sampling circuit and the current effective value circuit detect the apparent current, and the DSP main control chip calculates the frequency range corresponding to the maximum active current, and the calculation formula is Iactive=Iapparent*cosΦ. In this range, the difference of the current peak value within a cycle is used as the criterion for automatic frequency tracking.

[0021] A frequency tracking method for an automatic frequency tracking circuit of an ultrasonic cleaning machine power supply comprises the following steps:

[0022] S1, the ultrasonic power supply outputs from the minimum frequency to the maximum frequency in a certain step distance, evaluates the load, and continuously collects the active current during the process to form a frequency-active current response curve;

[0023] S2. After the load evaluation is completed, the frequency tracking method is started in the frequency range corresponding to the maximum active current, that is, the difference of the current peak value is calculated in each fixed large cycle Δ Imax, and the difference between the peak current of the previous large cycle ΔImax is compared. When the difference of the current peak value of this cycle is smaller than that of the previous cycle, the output frequency value of the next cycle is brought closer to the frequency value of the previous cycle; otherwise, the output frequency value of the next cycle is moved away from the frequency value of the previous cycle, and this process is repeated.

[0024] The working principle of the present invention is as follows: the power supply of the ultrasonic cleaning machine is automatically frequency tracking circuit, the power supply passes through the EMI circuit, the X1 capacitor, the common mode inductor L1 and the Y capacitors Y1 and Y2 in the EMI circuit are subjected to anti-interference processing, the rectifier diodes D1, D2, D3 and D4 in the rectifier circuit are subjected to full-wave rectification, C1 in the rectifier circuit filters the rectified voltage into pulsating direct current, and then outputs it to the full-bridge phase-shift circuit, the IGBTs G1, G2, G3 and G4 in the full-bridge phase-shift circuit invert and amplify the pulsating direct current according to the frequency output by the DSP main control chip, and then output it to the primary side of the transformer T1 in the matching circuit, the transformer T1 transfers the energy of the primary side to the series resonant circuit composed of the inductor L2 and the transducer, and completes an energy transfer. When the full-bridge phase-shift circuit inverts and amplifies the energy flowing through it and transfers it out through transformer T1, voltage V and current C are generated in the output loop of the full-bridge phase-shift circuit. Voltage transformer CT1 and current transformer CT2 in the sampling circuit will induce voltage signals of the same proportion. After being conditioned by operational amplifiers U1A and U1B, they are sent to the phase detection circuit and the current effective value circuit respectively. The logic chips U2A, U2B and D-flip-flop chips U3A, U3B in the phase detection circuit separate the phase advance and lag between the current signal and the voltage signal, and send them to operational amplifier U3. U3 converts the phase difference into a voltage signal and sends it to the DSP main control chip for processing. U4 in the current effective value circuit converts the conditioned current signal into a voltage value corresponding to the current RMS value, and sends it to the DSP main control chip for processing. The sampling circuit and the phase detection circuit detect the phase difference Φ, the sampling circuit and the current effective value circuit detect the apparent current, and the DSP main control chip calculates the frequency interval corresponding to the maximum active current. The calculation formula is Iactive = Iapparent * cosΦ. In this interval, the difference in the current peak value within a cycle is used as the criterion for automatic frequency tracking. The ultrasonic power supply outputs from the minimum frequency to the maximum frequency in a certain step distance in turn, and evaluates the load. During this period, the active current is continuously collected to form a frequency-active current response curve. After the load evaluation is completed, the frequency tracking method is turned on in the frequency interval corresponding to the maximum active current, that is, the difference in the current peak value is calculated for each fixed large cycle, and compared with the difference in the current value of the previous large cycle. When the difference in the current peak value of this cycle is smaller than that of the previous cycle, the output frequency value of the next cycle is brought closer to the previous cycle; otherwise, the output frequency value of the next cycle is moved away from the frequency value of the previous cycle, and this is repeated.

[0025] The present invention and its implementation methods are described, and such description is not restrictive. The drawings only describe one implementation method of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design structural methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. An automatic frequency tracking circuit for power supply of an ultrasonic cleaning machine, comprising an output control module and an input sampling module, characterized in that: The output control module includes an EMI circuit, a rectifier circuit, a full-bridge phase shift circuit, a matching circuit and a DSP main control chip. The EMI circuit is signal-connected to the rectifier circuit, the rectifier circuit is signal-connected to the full-bridge phase shift circuit, the full-bridge phase shift circuit is signal-connected to the matching circuit, and the full-bridge phase shift circuit is signal-connected to the DSP main control chip. The input sampling module includes a sampling circuit, a phase detection circuit, a current effective value calculation circuit and a DSP main control chip. The sampling circuit is signal-connected to the phase detection circuit, the phase detection circuit is signal-connected to the current effective value calculation circuit, the phase detection circuit and the current effective value calculation circuit are signal-connected to the DSP main control chip. The DSP main control chip is signal-connected with a start-stop button. The EMI circuit is electrically connected to the power supply. The output control module and the input sampling module form a real-time closed-loop feedback system when working. When the full-bridge phase-shift circuit inverts and amplifies the energy flowing through it and transfers it out through the transformer T1, a voltage V and a current C are generated on the output loop of the full-bridge phase-shift circuit. The voltage transformer CT1 and the current transformer CT2 in the sampling circuit will induce voltage signals of the same proportion. The voltage signal induced by the voltage transformer CT1 is sent to the phase detection circuit after conditioning by the U1A operational amplifier. The voltage signal induced by the current transformer CT2 is sent to the phase detection circuit and the current effective value circuit after conditioning by the U1B operational amplifier. The logic chips U2A, U2B and the D-type flip-flop chips U3A, U3B in the phase detection circuit separate the phase advance and lag between the current signal and the voltage signal, and send them to the operational amplifier U3. U3 converts the phase difference into a voltage signal and sends it to the DSP main control chip for processing. U4 in the current effective value circuit converts the conditioned current signal into a voltage value corresponding to the current RMS value, and sends it to the DSP main control chip for processing.

2. The automatic frequency tracking circuit for power supply of an ultrasonic cleaning machine according to claim 1, characterized in that: The power supply passes through the EMI circuit, and the X1 capacitor, common mode inductor L1 and Y capacitors Y1 and Y2 in the EMI circuit perform anti-interference processing. The rectifier diodes D1, D2, D3 and D4 in the rectifier circuit perform full-wave rectification. C1 in the rectifier circuit filters the rectified voltage into pulsating direct current, and then outputs it to the full-bridge phase-shift circuit. The IGBTs G1, G2, G3 and G4 in the full-bridge phase-shift circuit invert and amplify the pulsating direct current according to the frequency output by the DSP main control chip, and then output it to the primary side of the transformer T1 in the matching circuit. The transformer T1 transfers the energy of the primary side to the series resonant circuit composed of the inductor L2 and the transducer, completing an energy transfer.

3. The automatic frequency tracking circuit for power supply of an ultrasonic cleaning machine according to claim 1, characterized in that: The sampling circuit and the phase detection circuit detect the phase difference Φ, the sampling circuit and the current effective value circuit detect the apparent current, and the DSP main control chip calculates the frequency interval corresponding to the maximum active current. The calculation formula is Iactive=Iapparent*cosΦ. In this interval, the difference of the current peak value within a large cycle is used. Δ Imax is used as the criterion for automatic frequency tracking.

4. A frequency tracking method for an automatic frequency tracking circuit of an ultrasonic cleaning machine power supply, used in an automatic frequency tracking circuit of an ultrasonic cleaning machine power supply according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, the ultrasonic power supply outputs from the minimum frequency to the maximum frequency in a certain step distance, evaluates the load, and continuously collects the active current during the process to form a frequency-active current response curve; S2. After the load evaluation is completed, the frequency tracking method is started in the frequency range corresponding to the maximum active current, that is, the difference of the current peak value is calculated in each fixed large cycle Δ Imax, and the difference between the peak current of the previous large cycle Δ Imax is compared. When the difference of the current peak value of this cycle is smaller than that of the previous cycle, the output frequency value of the next cycle is brought closer to that of the previous cycle. On the contrary, the output frequency value of the next cycle is moved away from the frequency value of the previous cycle, and this process is repeated.

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