WO2020029695A1

WO2020029695A1 - Cooking appliance and ultrasonic oscillator drive control method and apparatus

Info

Publication number: WO2020029695A1
Application number: PCT/CN2019/092900
Authority: WO
Inventors: 曾露添; 雷俊; 梅若愚; 王云峰
Original assignee: 佛山市顺德区美的电热电器制造有限公司
Priority date: 2018-08-07
Filing date: 2019-06-26
Publication date: 2020-02-13

Abstract

A cooking appliance and an ultrasonic oscillator drive control method and apparatus, the ultrasonic oscillator drive control method comprising the following steps: acquiring state parameters of a resonant circuit in which the ultrasonic oscillator is located (S1); and, on the basis of the state parameters, adjusting the frequency of an alternating current control signal of the resonant circuit (S2). The present method can adjust the frequency of the alternating current control signal of the resonant circuit on the basis of the state parameters of the resonant circuit in which the ultrasonic oscillator is located, such that the new PWM frequency is consistent with the LC intrinsic frequency after drift and the ultrasonic transducer works in the best state, implementing automatic tracking of the frequency, and effectively increasing the reliability of the product and the service life of the product.

Description

Cooking appliance and driving control method and device of ultrasonic vibrator

Cross-reference to related applications

This application is based on application numbers 201810892151.0, 201810891077.0, application date is August 07, 2018, and 201811442158.9, 201811442170.X, and the application date is a Chinese patent application filed on November 29, 2018, and claims the priority of the Chinese patent application , The entire content of this Chinese patent application is incorporated herein by reference.

Technical field

The present application relates to the technical field of electrical appliances, and in particular, to a cooking appliance and a driving control method and device for an ultrasonic vibrator.

Background technique

Because the pressure in the pressure cooker during cooking is high, the food cannot roll, making the food unable to tumble, the nutrients are difficult to precipitate, and the porridge soup has a light taste.

In the related art, when an ultrasonic transducer vibrator rod is placed in water in a pot, when the ultrasonic vibrator vibrates, high-frequency mechanical vibrations of water molecules in the pot are transmitted to the food to decompose food nutrients. Among them, the ultrasonic transducer is an important core component of ultrasonic pressure cooking. Ultrasonic transducers are generally made of piezoelectric materials. The electrical characteristics of the transducer are external capacitive impedance. The capacitive load will generate reactive power and the output power factor is low. A matching inductive component is needed to make the ultrasonic drive system work in a resistive state.

However, in the related technology, the ultrasonic vibrator driving technology is to input a fixed frequency AC signal to the input end of the ultrasonic vibrator LC resonance circuit to control the ultrasonic vibrator to work. It does not detect the working state of the ultrasonic transducer. Because the ultrasonic vibrator works during vibration, Affected by changes in temperature, pressure, load, and other conditions, changes in the electrical parameters of the ultrasonic oscillator will cause the natural frequency of the ultrasonic oscillator to drift. This drift will easily increase the reactive component of the circuit and increase the reactive power, which will cause the temperature to rise further. Transducer components are prone to damage and reduce product life.

Application content

This application is intended to solve at least one of the technical problems in the related technology. Therefore, the first purpose of this application is to propose a method for driving and controlling an ultrasonic oscillator, which can adjust the frequency of the AC control signal of the resonant circuit according to the state parameters of the resonant circuit where the ultrasonic oscillator is located, so that a new PWM (Pulse Width Modulation, pulse (Wide modulation technology) The frequency is consistent with the natural frequency of the LC after the drift. The ultrasonic transducer works in the best state to achieve automatic frequency tracking, which effectively improves product reliability and product life.

The second object of the present application is to propose another driving control method for an ultrasonic vibrator.

A third object of the present application is to provide a driving control device for an ultrasonic vibrator.

A fourth object of the present application is to propose another driving control device for an ultrasonic vibrator.

A fifth object of the present application is to propose a cooking appliance.

A sixth object of the present application is to propose an electronic device.

A seventh object of the present application is to propose a non-transitory computer-readable storage medium.

In order to achieve the above object, an embodiment of the first aspect of the present application proposes a method for driving and controlling an ultrasonic oscillator, including the following steps: obtaining a state parameter of a resonance circuit where the ultrasonic oscillator is located; and adjusting the resonance circuit according to the state parameter The frequency of the AC control signal.

In addition, the method for driving and controlling the ultrasonic transducer according to the foregoing embodiment of the present application may also have the following additional technical features:

According to an embodiment of the present application, the obtaining a state parameter of a resonance circuit where the ultrasonic oscillator is located includes: obtaining a phase of an AC current signal of the resonance circuit where the ultrasonic oscillator is located; and adjusting the according to the state parameter. The frequency of the AC control signal of the resonance circuit includes: calculating a difference between a phase of the AC control signal input to the resonance circuit and a phase of the AC current signal; and adjusting the frequency of the AC control signal according to the difference.

According to an embodiment of the present application, adjusting the frequency of the AC control signal according to the difference includes: identifying that the difference is greater than or less than 0, then adjusting the frequency; identifying that the current difference is equal to 0 , Then keep the frequency unchanged.

According to an embodiment of the present application, the identifying the difference is greater than or less than 0, and then adjusting the frequency includes: identifying the difference is less than 0, increasing the frequency, and identifying the difference is greater than 0. , Then reduce the frequency.

According to an embodiment of the present application, obtaining the state parameter of the resonance circuit where the ultrasonic oscillator is located includes: obtaining a current of the resonance circuit where the ultrasonic oscillator is located; and adjusting the AC of the resonance circuit according to the state parameter. The frequency of the control signal includes: adjusting a frequency of an AC control signal input to the resonance circuit according to the current.

According to an embodiment of the present application, adjusting the frequency of the AC control signal input to the resonance circuit according to the current includes: identifying that the current is greater than or less than a preset current threshold, and then adjusting the frequency, so that The current threshold is less than the maximum resonance current of the resonance circuit; if the current is identified to be equal to the current threshold, the frequency is kept unchanged.

According to an embodiment of the present application, the identifying the current is greater than or less than a preset current threshold, and adjusting the frequency includes: identifying the current is less than the current threshold, increasing the frequency; identifying the If the current is greater than the current threshold, the frequency is reduced.

According to an embodiment of the present application, the increasing the frequency includes: reducing the period of the AC control signal by 1; the decreasing the frequency includes: increasing the period of the AC control signal by 1.

According to the driving control method of the ultrasonic vibrator according to the embodiment of the present application, the state parameters of the resonant circuit where the ultrasonic vibrator is located can be obtained, and the frequency of the AC control signal of the resonant circuit can be adjusted according to the state parameters. Therefore, by monitoring the current in the LC resonant circuit of the ultrasonic transducer or the phase of the current in the LC resonant circuit of the ultrasonic transducer, the controller has the ability to obtain the working state of the ultrasonic transducer, thereby adjusting the frequency of the PWM signal, thereby The new PWM frequency is consistent with the natural frequency of the LC after the drift, and the ultrasonic transducer works in the best state, realizing automatic frequency tracking, effectively improving product reliability and increasing product life.

In order to achieve the above object, an embodiment of the second aspect of the present application proposes another driving control method for an ultrasonic vibrator, including the following steps: detecting a state parameter of the ultrasonic transducer in real time; and outputting a drive according to the state parameter of the ultrasonic transducer A signal is sent to the excitation circuit, so that the excitation circuit provides excitation power for the resonance circuit of the ultrasonic transducer.

According to an embodiment of the present application, the detecting the state parameter of the ultrasonic transducer in real time includes: detecting the voltage across the ultrasonic transducer in real time as the state parameter.

According to an embodiment of the present application, the detecting the state parameter of the ultrasonic transducer in real time includes: detecting the temperature of the ultrasonic transducer in real time as the state parameter.

According to the driving control method of the ultrasonic transducer according to the embodiment of the present application, the state parameters of the ultrasonic transducer can be detected in real time, and a driving signal is output to the excitation circuit according to the state parameters of the ultrasonic transducer, so that the excitation circuit is an ultrasonic transducer. The resonant circuit provides the excitation power. Therefore, by detecting a change in the voltage across the ultrasonic transducer or a change in the temperature of the ultrasonic transducer, the output frequency of the control signal is adjusted so that it is consistent with the resonance frequency of the current resonant circuit, so that the ultrasonic transducer works. In the best state, the automatic tracking of the frequency is realized, and the product life is effectively extended.

In order to achieve the above object, an embodiment of the third aspect of the present application proposes a driving control device for an ultrasonic vibrator, including: a first detection module for acquiring a state parameter of a resonance circuit where the ultrasonic vibrator is located; a control module for The state parameter adjusts the frequency of the AC control signal of the resonance circuit.

According to an embodiment of the present application, the detection module is configured to obtain a current phase signal corresponding to an AC current signal of a resonance circuit where the ultrasonic oscillator is located, and a phase of the current phase signal is consistent with a phase of the AC current signal; A control module, configured to calculate a difference between the phase of the AC control signal input to the resonance circuit and the phase of the current phase signal, and adjust the frequency of the AC control signal according to the difference, and output the adjusted The AC control signal.

According to an embodiment of the present application, the detection module is configured to obtain an AC current signal of a resonance circuit where the ultrasonic oscillator is located, convert the AC current signal into an AC voltage signal, and rectify the AC voltage signal. A filtering process is performed to obtain a DC voltage signal; a control module is configured to adjust the frequency of the AC control signal input to the resonance circuit according to the DC voltage signal, and output the AC control signal.

According to an embodiment of the present application, the detection module includes: a current sampling module for acquiring the AC current signal and converting the AC current signal into an AC voltage signal; an amplitude limit module for converting the AC current signal The amplitude of the AC voltage signal is limited within a set amplitude range to generate a limited AC voltage signal; a reference voltage module is used to generate a reference voltage signal; a phase comparison module is used to The reference voltage signal generates the current phase signal.

According to an embodiment of the present application, the current sampling module includes: a current transformer, configured to convert the input AC current signal of a first amplitude to the AC current signal of a second amplitude, the first Two amplitude values are smaller than the first amplitude value, and output the AC current signal of the second amplitude value; a load resistance, the load resistance is connected in parallel with the current transformer, and is used to connect the second amplitude value The AC current signal is converted into the AC voltage signal.

According to an embodiment of the present application, the amplitude limiting module includes: a current limiting resistor, a first terminal of the current limiting resistor is connected to a first output terminal of the current sampling module, and a second terminal of the current limiting resistor Terminal is connected to the input positive terminal of the phase comparison module; a first diode, the anode of the first diode is connected to the input positive terminal of the phase comparison module, and the cathode of the first diode is respectively Connected to the input negative terminal of the phase comparison module and the first output terminal of the current sampling module; a second diode, the anode of the second diode is connected to the input negative terminal of the phase comparison module, The cathode of the second diode is connected to the input positive terminal of the phase comparison module.

According to an embodiment of the present application, the reference voltage module includes: a first voltage dividing resistor, a first end of the first voltage dividing resistor being connected to a first DC power source; a second voltage dividing resistor, the second The first end of the voltage dividing resistor is respectively connected to the second end of the first voltage dividing resistor and the input negative terminal of the phase comparison module, and the second end of the second voltage dividing resistor is grounded; the filter capacitor, the A first terminal of the filter capacitor is connected to an input negative terminal of the phase comparison module, and a second terminal of the filter capacitor is grounded.

According to an embodiment of the present application, the phase comparison module includes: a phase comparator, an in-phase input terminal of the phase comparator is connected to a first output terminal of the amplitude limit module, and an inversion of the phase comparator The input terminal is respectively connected to the second output terminal of the amplitude limiting module and the output terminal of the reference voltage module.

According to an embodiment of the present application, the detection module further includes a rectification and filtering module, configured to rectify and filter the AC voltage signal to obtain a DC voltage signal.

According to an embodiment of the present application, the rectifying and filtering module includes: a rectifying diode for rectifying the AC voltage signal to obtain the pulsating DC voltage signal; and a filtering capacitor for rectifying the pulsating voltage. The DC voltage signal is filtered to obtain a smooth DC voltage signal.

According to the driving control device for an ultrasonic oscillator according to the embodiment of the present application, the state parameters of the resonance circuit where the ultrasonic oscillator is located can be obtained through the first detection module, and the frequency of the AC control signal of the resonance circuit is adjusted by the control module according to the state parameters. Therefore, by monitoring the current in the LC resonant circuit of the ultrasonic transducer or the phase of the current in the LC resonant circuit of the ultrasonic transducer, the controller has the ability to obtain the working state of the ultrasonic transducer, thereby adjusting the frequency of the PWM signal, thereby The new PWM frequency is consistent with the natural frequency of the LC after the drift, and the ultrasonic transducer works in the best state, realizing automatic frequency tracking, effectively improving product reliability and increasing product life.

In order to achieve the above object, an embodiment of the fourth aspect of the present application proposes another driving control device for an ultrasonic transducer, including: a second detection module for detecting a state parameter of the ultrasonic transducer in real time; and a driving module for The state parameter of the ultrasonic transducer outputs a driving signal to an excitation circuit, so that the excitation circuit provides an excitation power source for a resonance circuit of the ultrasonic transducer.

According to the driving control device of the ultrasonic transducer according to the embodiment of the present application, the state parameters of the ultrasonic transducer are detected in real time by the second detection module, and the driving module outputs a driving signal to the excitation circuit according to the state parameters of the ultrasonic transducer, so that the excitation The circuit provides excitation power for the resonance circuit of the ultrasonic transducer. Therefore, by detecting a change in the voltage across the ultrasonic transducer or a change in the temperature of the ultrasonic transducer, the output frequency of the control signal is adjusted so that it is consistent with the resonance frequency of the current resonant circuit, so that the ultrasonic transducer works. In the best state, the automatic tracking of the frequency is realized, and the product life is effectively extended.

In order to achieve the above object, an embodiment of the fifth aspect of the present application provides a cooking appliance, which includes an ultrasonic oscillator and a driving control device for the ultrasonic oscillator according to the third aspect of the present invention, or is implemented as the fourth aspect of the present invention. The drive control device for the ultrasonic transducer according to the example.

According to the cooking appliance of the embodiment of the present application, the state parameter of the resonance circuit where the ultrasonic oscillator is located can be obtained by the first detection module, and the frequency of the AC control signal of the resonance circuit can be adjusted by the control module according to the state parameter. Therefore, by monitoring the current in the LC resonant circuit of the ultrasonic transducer or the phase of the current in the LC resonant circuit of the ultrasonic transducer, the controller has the ability to obtain the working state of the ultrasonic transducer, thereby adjusting the frequency of the PWM signal, thereby Make the new PWM frequency consistent with the natural frequency of the LC after the drift, and the ultrasonic transducer works at the best state to achieve automatic frequency tracking, effectively improve the reliability of the product and increase the product life; it can also be detected in real time by the second detection module The state parameter of the ultrasonic transducer, and the driving module outputs a driving signal to the excitation circuit according to the state parameter of the ultrasonic transducer, so that the excitation circuit provides excitation power for the resonance circuit of the ultrasonic transducer. Therefore, by detecting a change in the voltage across the ultrasonic transducer or a change in the temperature of the ultrasonic transducer, the output frequency of the control signal is adjusted so that it is consistent with the resonance frequency of the current resonant circuit, so that the ultrasonic transducer works. In the best state, the automatic tracking of the frequency is realized, and the product life is effectively extended. .

To achieve the above object, an embodiment of the sixth aspect of the present application provides an electronic device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor executes In the program, the driving control method for the ultrasonic transducer according to the first aspect of the present invention or the driving control method for the ultrasonic transducer according to the second aspect of the present invention is implemented.

In order to achieve the above object, an embodiment of the seventh aspect of the present application proposes a non-transitory computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the implementation of the first aspect of the present invention is implemented. A driving control method for an ultrasonic vibrator, or a driving control method for an ultrasonic vibrator according to the embodiment of the second aspect of the present invention.

Additional aspects and advantages of the present application will be given in part in the following description, part of which will become apparent from the following description, or be learned through practice of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a flowchart of a driving control method of an ultrasonic vibrator according to an embodiment of the present application;

2 is a schematic block diagram of a driving control circuit of an ultrasonic transducer according to an embodiment of the present application;

3 is a schematic structural diagram of a driving control circuit of an ultrasonic transducer according to an embodiment of the present application;

4 is a schematic block diagram of a driving control circuit of an ultrasonic transducer according to another embodiment of the present application;

5 is a schematic structural diagram of a driving control circuit of an ultrasonic transducer according to another embodiment of the present application;

6 is a waveform diagram of a driving control circuit of an ultrasonic transducer according to an embodiment of the present application;

7 is a schematic diagram of a relationship between a PWM frequency control and a current according to an embodiment of the present application;

8 is a waveform diagram of a driving control circuit of an ultrasonic transducer according to another embodiment of the present invention;

9 is a flowchart of a driving control method of an ultrasonic transducer according to an embodiment of the present application;

10 is a flowchart of a driving control method of an ultrasonic transducer according to a specific embodiment of the present application;

11 is a flowchart of a driving control method for an ultrasonic transducer according to still another embodiment of the present application;

12 is a schematic diagram of a relationship between a PWM frequency control and a current according to an embodiment of the present invention;

13 is a flowchart of a PWM frequency tracking control step according to an embodiment of the present invention;

14 is a flowchart of a driving control method for an ultrasonic transducer according to an embodiment of the present application;

15 is a structural block diagram of a driving control device for an ultrasonic transducer according to an embodiment of the present invention;

16 is a circuit topology diagram of a driving control device for an ultrasonic transducer according to an embodiment of the present invention;

17 is a graph showing a relationship between a resonance frequency of a resonance circuit and a temperature of an ultrasonic transducer according to an embodiment of the present invention;

18 is a working flowchart of a controller according to an embodiment of the present invention;

19 is a structural block diagram of a drive control device for an ultrasonic transducer according to another embodiment of the present invention;

20 is a circuit topology diagram of a driving control device for an ultrasonic transducer according to another embodiment of the present invention;

21 is a graph showing a relationship between an output frequency of a driving signal and an output power of an ultrasonic transducer according to an embodiment of the present invention;

22 is a working flowchart of a controller according to another embodiment of the present invention;

23 is a schematic block diagram of a driving control device for an ultrasonic transducer according to an embodiment of the present application;

FIG. 24 is a schematic block diagram of a driving control device for an ultrasonic transducer according to another embodiment of the present application.

detailed description

Hereinafter, embodiments of the present application will be described in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary, and are intended to explain the present application, and should not be construed as limiting the present application.

The following describes the cooking appliance and the driving control method and device of the ultrasonic oscillator according to the embodiments of the present application with reference to the drawings.

FIG. 1 is a flowchart of a driving control method for an ultrasonic transducer according to an embodiment of the present application.

As shown in FIG. 2, the driving control circuit of the ultrasonic vibrator involved in the driving control method of the ultrasonic vibrator according to the embodiment of the present application mainly includes: a main power circuit module 10, a control module 20, a driving module 30, and a detecting module 40.

Specifically, in conjunction with FIGS. 2 and 3, the main power circuit module 10 includes: an AC power input module 11, a rectification module 12, a filtering module 13, a voltage dividing module 14, a first switching tube 15, a second switching tube 16, and an isolation. Transformer module 17, resonant inductor 18, and ultrasonic transducer 19.

The AC power input module 11 includes: a terminal L, a terminal N, and a fuse F1. The AC power input module 11 includes a terminal for connecting a power source to a power outlet. The rectification module 12 includes a diode D1, a diode D2, a diode D3, and a diode D4. The rectification module 12 is configured to convert an AC voltage into a DC voltage. The filtering module 13 is configured to convert the changed DC voltage into a smooth DC voltage. The voltage-dividing module 14 includes a capacitor C2 and a capacitor C3. The voltage-dividing module 14 is configured to convert an input voltage to a midpoint voltage of half the input voltage. The first switching tube 15 may be a half-bridge upper-bridge switching tube. When the input terminal receives a low-level signal (such as 0V), the switching tube is turned off, that is, the drain (D) pole is disconnected from the source (S); a high level is received. The signal (such as 12V), the switch is turned on, that is, the drain (D) pole and the source (S) are turned on. The second switching tube 16 may be a half-bridge lower-bridge switching tube. When the input terminal receives a low-level signal (such as 0V), the switching tube is turned off, that is, the drain (D) pole and the source (S) are disconnected; a high level is received. The signal (such as 12V), the switch is turned on, that is, the drain (D) pole and the source (S) are turned on. The isolation transformer module 17 inputs one voltage and outputs another voltage, which is determined by the turns ratio of the input coil and the output coil, and at the same time electrically isolates the input voltage from the output voltage. The resonant inductor 18 and the ultrasonic transducer form an LC resonant loop, which increases the output power of the ultrasonic transducer. The ultrasonic transducer 19 is used to convert electrical energy into vibrational mechanical energy, which drives the water molecules in the pot to vibrate and transfers them to the food to decompose the food nutrients.

The control module 20 includes a controller 21 and a first power supply voltage 22. Among them, the controller 21 is used to receive the current signal of the ultrasonic transducer 19, and controls and outputs two complementary PWM signals through internal arithmetic processing to send to the half-bridge driver. The first power supply voltage 22 is used to provide a working power supply voltage for the controller 21.

The driving module 30 includes a half-bridge driver 31, a second power supply voltage 32 and a third power supply voltage 33. Among them, the half-bridge driver 31 is used to receive the two-channel common ground complementary PWM signal input from the controller 21, wherein the voltage range of the PWM signal is low-level 0V, high-level 3.3V or 5V; and a single common-ground signal is converted and output. The second switching tube 16 is driven and the first switching tube 15 is driven by a floating signal. The output voltage ranges from a low level of 0V and a high level of 12V. The second power supply voltage 32 is used to provide a power supply voltage for the common ground output control module of the driver 31. The third power supply voltage 33 is used to provide a power supply voltage for the floating output control module of the driver 31.

The detection module 40 includes a reference voltage module 41, a current sampling module 42, an amplitude limit module 43, and a phase comparison module 44. The detection module 40 can be used to detect the current phase of the transducer. The reference voltage module 41 includes an input power voltage, a first voltage dividing resistor R2, a second voltage dividing resistor R3, and a filter capacitor C5. The first voltage-dividing resistor R2 and the second voltage-dividing resistor R3 form a voltage-dividing circuit to provide a voltage reference for the inverting input terminal of the phase comparator; the current sampling module 42 includes a current transformer T2 and a load resistor R1. The current transformer T2 is used to convert a large current signal input to the resonance circuit of the ultrasonic transducer into a small current signal that is proportional to the current, and the load resistor R1 is used to convert the current signal into a voltage signal; the amplitude limit module 43 includes a limit A current resistor R4, a first diode D6, and a second diode D7. The amplitude limit module 43 is used to limit the voltage output by the current sampling module 42 to a certain amplitude, provide a safe signal voltage for the phase comparator chip, and prevent damage to the comparator chip; the phase comparison module 44 includes a phase comparison chip CMP1 and an output Pull-up resistor R5. The phase comparison chip includes two input terminals: a non-inverting input terminal and an inverting input terminal. The inverting input terminal is connected to the reference voltage output by the reference voltage module 41, and the non-inverting input terminal is connected to the output of the amplitude limit module 43. The phase comparison module 44 is configured to convert an analog current phase signal output by the current sampling module 42 into a digital phase signal, and then send it to the controller 21 for processing.

As shown in FIG. 4 and FIG. 5, the detection module 40 further includes a current rectification and filtering module 50. The current rectification and filtering module 50 includes a diode D6 and a capacitor C5. Among them, the diode D6 is used to convert an AC voltage into a DC voltage. Capacitor C5 is used to change the changed DC voltage into a smooth DC voltage and send it to the controller for voltage sampling.

In addition, the working principle of the method for driving and controlling the ultrasonic vibrator according to the embodiment of the present application will be briefly introduced.

With reference to FIG. 3, the first power supply voltage may be 5V for supplying power to the controller 21. The second power supply voltage may be 12V, which is used to power the lower-bridge output of the half-bridge driver chip. The third power supply voltage can be floating 12V, which is used to power the upper bridge of the half-bridge driver chip. The switching tubes Q1 and Q2 can be N-type MOSFETs. Q1, Q2, T1, C2, and C3 form a half-bridge push-pull circuit. The load is an isolation transformer T1. The isolation transformer T1 plays the role of isolation transformer and impedance conversion. The inductor L1 and the ultrasonic transducer Z1 form an LC resonance circuit, which is used to improve the output power and power factor of the ultrasonic transducer. The working waveform is shown in Figure 6:

During operation, the controller 21 outputs two complementary and common ground PWM signals. Among them, the two complementary signals refer to when one of them is at a high level and the other is at a low level, and the two PWM signals are alternately turned on, as shown in the figure. The time periods t1 and t2 in 6 are shown. In addition, in the transition time period when the PWM signal changes alternately, both signals are low level, which is called the dead time. The time period t3 shown in Figure 6 is used to prevent the switching of the upper and lower tubes Q1 and Q2. Causes simultaneous turn-on damage to the device.

The voltage capability of the controller 21 to output the PWM signal is 0 to 5V, and it is not possible to directly drive the MOSFET switches Q1 and Q2, and the two PWM signals output by the controller 21 are all grounded at the same time, that is, ground (voltage is 0V) as a reference Point, the voltage range of 0 ~ 5V, but the high-side switch Q1 is a floating switch, where the floating switch refers to the source (S) voltage of the high-side switch is changed, so the gate (G) The voltage also changes. For example, the voltage of the front-drain (D) pole of the upper-bridge switch Q1 is 300V and the source (S) pole voltage is 0V, so the gate-source voltage V _GS of Q1 is 0V. After the high-side switch Q1 is turned on, the D and S pins of Q1 are short-circuited. The source (S) voltage is 300V. To maintain Q1 conduction, the gate-source voltage V _{GS of} Q1 must maintain a 12V voltage difference. Then the gate voltage to ground must be 312V.

The floating 12V of the third power supply voltage is realized by the diode D5 and the capacitor C4. Specifically, when the lower-bridge switch Q2 is turned on, the D and S pins of Q2 are short-circuited, and the drain (D) voltage of Q2 is 0V. Then the VS pin of the half-bridge driver chip is 0V, and the + 12V power source passes D5. Charge capacitor C4 with a voltage of 12V. When the high-side switch Q1 is turned on, the D and S pins of Q1 are shorted, and the S pin of Q1 rises to 300V. Due to the presence of capacitor C4, the voltage across C4 remains unchanged at 12V, so the voltage of C4 to ground is 312V, so as to realize the floating power supply to the switch Q of the upper bridge.

The controller 21 outputs two PWM complementary signals with a voltage range of 0 to 5V to the half-bridge driver chip. After the internal voltage amplification and floating separation of the chip are sent to the gates of the upper and lower half-bridge switches, the half-bridge switch Q1 is driven. And Q2 are alternately turned on, so that the input terminal of the isolation transformer T1 generates an alternating voltage, and the output terminal also follows the input terminal to generate an alternating voltage, which excites the LC resonance circuit composed of the inductor L1 and the ultrasonic transducer Z1, so that the ultrasonic wave Transducer Z1 generates mechanical vibration, which converts electric field energy into mechanical energy, and drives high-frequency mechanical vibration of water molecules in the pot, and transfers it to food to decompose food nutrients.

The vibration frequency of the ultrasonic transducer Z1 is determined by the PWM signal output by the controller 21. The electrical characteristics of the ultrasonic transducer Z1 are capacitive impedance. After being connected in series with the inductor TL1, an LC resonance circuit is formed. Its natural frequency value is:

The LC resonance circuit has a frequency-selective characteristic for frequency. The output power of the transducer can be obtained according to the following formula:

P = U * I * cosθ;

Among them, U is the voltage across the vibrator, I is the current flowing through the vibrator, and θ is the phase difference between the voltage and the current across the vibrator.

Therefore, if the phase between the voltage and current of the transducer of the ultrasonic transducer is the same, that is, when the phase difference is 0, the load of the transducer is purely resistive and has the maximum output power. As shown in FIG. 7, the natural frequency of the transducer is F0. When the driving frequency f is the same as the natural frequency F0, the phase difference is 0 at this time, and the output power is maximum.

The natural resonance frequency of an ultrasonic transducer is not fixed. When it is affected by conditions such as temperature, pressure, or load changes, the natural resonance frequency will drift, which will increase the reactive component of the circuit and increase the reactive power. If the frequency of the PWM signal output by the controller 21 is not changed, the driving frequency is not consistent with the resonance frequency, the output power of the ultrasonic transducer is low, the power factor is also reduced, the working state of the ultrasonic transducer is deteriorated, and the life is shortened. Therefore, the controller 21 needs to sense the change of the working state of the ultrasonic transducer, adjust the frequency of the output PWM signal, and follow the change of the natural frequency of the ultrasonic transducer to keep the driving frequency and the resonance frequency consistent.

In one embodiment of the present application, the parameter preferred value is the primary coil N ₁ = 1 turn and the secondary coil N ₂ = 500 turns of the current sensor T2, according to the ampere loop law:

N ₁ × I ₁ = N ₂ × I ₂ ;

Then the secondary coil current:

I ₂ = N ₁ × I ₁ / N ₂ .

For example, the current flowing into the primary coil of the current transformer is 1000 milliamps. As shown in the N3 current waveform in FIG. 7, the secondary coil current is 2 milliamps. The load resistor R1 converts the current signal into a voltage signal; R1 is used as an example. The preferred resistance value is 1K, and the current flowing into R1 is 2 mA, then the voltage difference on R1 is:

V = I ₂ × R1 = 2V;

Thus, the effect of converting a current signal into a voltage signal is achieved. In the reference voltage module 41, the preferred value of R2 and R3 is 1K, and the preferred value of the capacitor C5 is 1 microfarad, so the reference voltage output voltage (N6 node) is 2.5V. The reference voltage is used to provide a suitable operating voltage for the input signal provided by the comparator CMP1. The inverting input of the comparator CMP1 is a reference voltage of 2.5V. The other end of the current-sampling load resistor is superimposed on the reference voltage. Therefore, as shown by the N4 waveform in FIG. 7, the 2V voltage of the above-mentioned R1 resistor is in the range of the voltage of the node N4 from 0.5V to 4.5V. In the voltage-limiting module 43, diodes D6 and D7 form a bidirectional voltage-limiting circuit. The voltage-limiting range is plus or minus 0.7V. As long as the voltage difference exceeds 0.7V, the voltage will be limited to 0.7V. On the reference voltage. Therefore, as shown by the N5 waveform in FIG. 7, the voltage range of the node N5 is 1.8V to 3.2V. The voltage at node N5 is connected to the non-inverting terminal of the comparator, and the 2.5V reference voltage is sent to the inverting terminal of the comparator. After the comparator CMP1, the waveform of its output terminal (node N7) is shown as N7 in FIG. 7. As can be seen from the comparison of the waveforms of node N3 and node N7 in FIG. 7, the waveform of node N7 reflects the current phase characteristics of the transducer oscillator, thereby realizing the acquisition of the current phase of the transducer. The collected phase signal is sent to the controller 21. Phase input pin.

In addition, the parameter is preferably the primary coil N ₁ = 1 turn and the secondary coil N ₂ = 500 turns of the current sensor T2, according to the ampere loop law:

N ₁ × I ₁ = N ₂ × I ₂ ;

Then the secondary coil current:

I ₂ = N ₁ × I ₁ / N ₂ .

For example, the current flowing into the primary coil of the current transformer is 1000 milliamps, as shown in the N3 current waveform in FIG. 8, and the secondary coil current is 2 milliamps, as shown in the N4 current waveform in FIG. 8.

The load resistor R1 can convert a current signal into a voltage signal. Preferably, the resistance value of R1 is 2.4K, and the current flowing into R1 is 2 mA, then the voltage on R1 is:

V = I ₂ × R1 = 4.8V.

Diode D6 and R5 form a half-wave rectification filter circuit. When the voltage on the R1 pin is positive, the diode D6 is turned on to charge the capacitor C5. Ignoring the voltage drop of the diode D6, the voltage on the capacitor C5 is 4.8V. This is shown by the N5 node voltage in Figure 8. The voltage on the capacitor C5 is sent to the analog-to-digital conversion pin (ADC pin) of the controller. After the internal analog-to-digital conversion, the analog voltage is converted into a digital voltage for the controller to process.

According to the above current detection principle, when the PWM drive frequency output by the controller is consistent with the LC resonance frequency, when the ultrasonic transducer works in the best state, the output power of the ultrasonic transducer is the largest, and the current of the LC resonance loop is the largest. When the natural resonant frequency of the ultrasonic transducer drifts, the driving frequency is not consistent with the resonant frequency, the output power of the ultrasonic transducer is reduced, and the current of the LC resonance loop is reduced. After analog-to-digital conversion, the current value obtained by the controller becomes smaller. After the PWM frequency tracking control method is processed, the PWM output signal frequency is adjusted until it is adjusted to the offset resonance frequency. As shown in FIG. 1, the driving control method of the ultrasonic vibrator includes the following steps:

S1. Obtain state parameters of the resonance circuit where the ultrasonic oscillator is located.

S2. Adjust the frequency of the AC control signal of the resonance circuit according to the state parameter.

As shown in FIG. 9, in an embodiment of the present application, when obtaining the phase of the AC current signal of the resonance circuit where the ultrasonic oscillator is located, the method includes the following steps:

S901. Obtain a phase of an AC current signal of a resonance circuit where an ultrasonic oscillator is located.

It can be understood that the phase of the AC current signal of the resonance circuit where the ultrasonic oscillator is located can be collected through the phase detection module.

S902: Calculate the difference between the phase of the AC control signal and the phase of the AC current signal input to the resonance circuit.

Specifically, the AC control signal of the resonance circuit can be output by the controller, as shown in the PWMP waveform in FIG. 6, which reflects the voltage phase signal of the oscillator. Since PWMP is output by the controller, its phase signal Is known. The phase of the AC current signal can be shown as the node N7 waveform in FIG. 6, which reflects the current phase signal of the vibrator. The controller can detect the current phase signal of the vibrator and calculate the phase difference between them by operation. The phase difference can be shown as tp in FIG. 6. The calculation method may be a calculation method in the related art, and is not specifically limited herein.

S903. Adjust the frequency of the AC control signal according to the difference.

It can be understood that, in the embodiment of the present application, the frequency of the AC control signal can be adjusted by calculating the phase difference between the phase of the current AC current signal and the voltage signal input to the resonance circuit.

Specifically, as shown by tp in FIG. 6, the embodiment of the present application can control the frequency change of the PWM signal according to the magnitude of the phase difference tp.

Further, according to an embodiment of the present application, adjusting the frequency of the AC control signal according to the difference includes: if the difference is greater than or less than 0, adjusting the frequency; if the current difference is equal to 0, keeping the frequency unchanged.

It can be understood that, as shown in FIG. 7, according to the characteristics of the relationship between the driving frequency and the output power of the vibrator and the voltage and current phase of the vibrator, it can be seen that: (1) the PWM driving frequency f output by the controller is in the entire frequency range Only when the driving frequency f is equal to the natural resonant frequency F0 of the transducer element, the maximum output power is obtained; (2) The phase difference between the voltage and the current at the maximum output power of the transducer is 0.

Therefore, when adjusting the frequency of the AC control signal according to the difference between the phase of the AC control signal and the phase of the AC current signal input to the resonance circuit, if the difference is equal to 0, it means that the current PWM driving frequency is equal to the inherent nature of the transducer oscillator. Resonant frequency, the transducer load is purely resistive, has the maximum output power, works in the best state, the controller can keep the current PWM signal frequency unchanged; if the difference is not equal to 0, such as the difference is greater or less than 0, It means that the current PWM drive frequency deviates from the natural resonance frequency of the transducer oscillator, and the current drive frequency of the PWM signal needs to be adjusted.

Further, according to an embodiment of the present application, if the difference is greater than or less than 0, adjusting the frequency includes: if the difference is less than 0, increasing the frequency; if the difference is greater than 0, reducing the frequency.

According to an embodiment of the present application, increasing the frequency includes: reducing the period of the AC control signal by 1; decreasing the frequency includes: increasing the period of the AC control signal by 1.

Specifically, if the difference between the phase of the AC control signal and the phase of the AC current signal input to the resonance circuit is less than 0, it means that the current PWM driving frequency is less than the natural resonance frequency of the transducer, and the frequency of the PWM output signal needs to be increased; If the difference between the phase of the AC control signal and the phase of the AC current signal input to the resonance circuit is greater than 0, it means that the current PWM driving frequency is greater than the natural resonance frequency of the transducer, and the frequency of the PWM output signal needs to be reduced.

For example, as shown in FIG. 10, in a specific embodiment of the present application, the above-mentioned driving control method for an ultrasonic transducer includes the following steps:

S601. Obtain an AC current signal phase value of a resonance circuit where an ultrasonic oscillator is located.

S602. Calculate the phase difference between the phase of the AC control signal and the AC current signal input to the resonance circuit.

S603: Determine whether the phase difference value is equal to 0. If yes, perform step S604; otherwise, perform step S605.

S604. The controller keeps the current PWM signal frequency unchanged.

S605: Determine whether the phase difference value is less than 0. If yes, perform step S606; otherwise, perform step S607.

S606: The PWM cycle value is decreased by 1, and then the adjustment is ended.

In S607, the PWM cycle value is increased by 1, and then the adjustment is ended.

That is, after the controller can obtain the current phase signal of the transducer of the ultrasonic transducer through the above principle, it can be processed by an internal control program algorithm to adjust the frequency of the current PWM signal to achieve automatic frequency tracking.

Specifically, it is assumed that the current ultrasonic transducer works in an optimal state, at this time, the frequency f of the PWM output by the controller is 40KHz, and the phase difference between the voltage and the current detected by the controller of the controller is 0. Due to the influence of temperature, pressure or load changes, the natural resonant frequency F0 of the vibrator will shift from 40KHz to 41KHz. Because the driving frequency f is not equal to the new natural resonant frequency 41KHz, therefore, the ultrasonic transducer After the natural resonance frequency is shifted, the phase difference detected by the controller is less than 0. You can control the PWM cycle value to decrease by performing the above step S606. It can be known from the formula f = 1 / T that the frequency of the controller output PWM will increase. When the PWM frequency output by the controller rises to 41KHz, the driving frequency is equal to the natural resonance frequency, the detected phase difference is equal to 0, and the controller keeps the current PWM frequency unchanged, thereby achieving automatic frequency tracking of the ultrasonic transducer.

Based on the same control principle, the natural resonance frequency of the oscillator is shifted from 40KHz to 39KHz. Because the driving frequency f is not equal to the new natural resonance frequency of 39KHz, the natural resonance frequency of the ultrasonic transducer is shifted. If the phase difference is greater than 0, you can control the PWM cycle value to increase by performing the above step S606. It can be known from the formula f = 1 / T that the frequency of the controller output PWM will decrease. When the PWM frequency of the controller decreases to 39KHz, the drive The frequency is equal to the natural resonance frequency, the detected phase difference is equal to 0, and the controller keeps the current PWM frequency unchanged, so as to achieve automatic frequency tracking of the ultrasonic transducer.

As shown in FIG. 11, in an embodiment of the present application, when obtaining the phase of the AC current signal of the resonance circuit where the ultrasonic oscillator is located, the method includes the following steps:

S1101: Obtain the current of the resonance circuit where the ultrasonic oscillator is located.

It can be understood that, in the embodiment of the present application, the state parameters of the resonance circuit where the ultrasonic oscillator is located can be collected by the detection module, wherein the state parameters include the current of the resonance circuit where the ultrasonic oscillator is located and the phase of the AC current signal of the resonance circuit where the ultrasonic oscillator is located.

S1102: Adjust the frequency of the AC control signal input to the resonance circuit according to the current.

According to an embodiment of the present invention, adjusting the frequency of the AC control signal input to the resonant circuit according to the current includes: identifying that the current is greater than or less than a preset current threshold, then adjusting the frequency, and the current threshold is smaller than the maximum resonant current of the resonant circuit; identifying If the current is equal to the current threshold, the frequency remains unchanged.

Further, according to an embodiment of the present invention, adjusting the frequency when the recognition current is greater than or less than a preset current threshold includes: if the recognition current is less than the current threshold, increasing the frequency; if the recognition current is greater than the current threshold, reducing the frequency.

According to an embodiment of the present invention, increasing the frequency includes: reducing the period of the AC control signal by 1; decreasing the frequency includes: increasing the period of the AC control signal by 1.

Specifically, as shown in FIG. 12, the optimal resonance frequency of the LC resonance composed of the ultrasonic transducer Z1 and the inductor L1 is F0, and at this time, the maximum output power and the resonance current are also maximum. The farther the excitation frequency output by the controller is away from the F0 frequency, the smaller the output power of the ultrasonic transducer Z1, and the smaller the resonance current. As shown in FIG. 12, the excitation frequency f and the resonance current output by the controller have a gimmick waveform. Below F0 frequency, the larger the excitation frequency f, the larger the resonance current, which is a one-way increasing relationship; above F0 frequency, the larger the excitation frequency f, the smaller the resonance current, which is a one-way decreasing relationship. In the actual design of the program, a curve segment with a one-way increasing relationship is used to preset a maximum current value I1, as shown in FIG. 12. At this time, the excitation frequency f1 reaching the current I1 will be slightly smaller than F0 to prevent the program control curve. Cross the boundary and enter the one-way decreasing relationship curve segment.

Specifically, the embodiment of the present invention can analyze the foregoing control principle to the embodiment of the present invention.

As shown in Figure 13, the PWM frequency tracking control method includes the following steps:

In step S501, analog-to-digital conversion is started to obtain the current voltage value of the ADC pin.

In step S502, it is determined whether the current voltage value of the ADC pin is equal to a preset value. If so, step S506 is performed; otherwise, step S503 is performed.

In step S503, it is determined whether the current voltage value of the ADC pin is less than a preset value. If so, step S504 is performed; otherwise, step S505 is performed.

In step S504, the PWM period value is decreased by 1, and step S506 is executed.

In step S505, the PWM period value is increased by one.

Step S506: Exit the control method.

Specifically, the analog-to-digital conversion is started to obtain the current voltage value of the ADC pin. As shown in FIG. 13, the obtained current voltage value of the ADC pin reflects the resonance current value of the LC resonance circuit.

Secondly, determine whether the current resonance current is equal to the preset current, and if so, exit the control method. If the current resonance current is equal to the preset current, it means that the current frequency of the output PWM of the controller is working near the natural frequency. On the other hand, the output power is large, the power factor is high, and it has the best state. There is no need to adjust the current PWM frequency;

Otherwise, it is determined whether the current resonance current is less than a preset current.

If the current resonance current is less than the preset current, the PWM cycle value is reduced by 1, and then exit the control method. As shown in FIG. 12, the control method of the embodiment of the present invention requires a curve segment with a one-way increasing relationship, which requires an increase in the output frequency. Increase the output current. The relationship between the frequency F and the period T of the PWM is: F = 1 / T, the frequency F and the period T are inversely proportional. The PWM period decreases and the frequency increases, so that the output current can be controlled to increase.

If the current resonance current is greater than the preset current, the PWM cycle value is increased by 1, and then exit this control method. According to the above, the PWM cycle is increased and the frequency is reduced, so that the output current can be controlled to be reduced.

According to the driving control method for an ultrasonic oscillator provided in the embodiment of the present application, the phase of the AC current signal of the resonance circuit where the ultrasonic oscillator is located can be obtained, and the difference between the phase of the AC control signal input to the resonance circuit and the phase of the AC current signal, To adjust the frequency of the AC control signal based on the difference. Therefore, by monitoring the current phase in the LC resonance circuit of the ultrasonic transducer and sending it to the controller, the controller calculates the phase difference between the current and the voltage, and adjusts the frequency of the PWM signal, so that the new PWM frequency is in phase with the LC natural frequency after the drift. Consistently, the ultrasonic transducer works in the best state, realizing automatic frequency tracking, effectively improving product reliability and increasing product life.

FIG. 14 is a flowchart of a driving control method of an ultrasonic transducer according to another embodiment of the present application. As shown in FIG. 14, the driving control method of the ultrasonic vibrator includes:

S1401: Detect the state parameters of the ultrasonic transducer in real time.

According to an embodiment of the present application, detecting the state parameter of the ultrasonic transducer in real time includes: detecting the temperature of the ultrasonic wave transducer in real time as the state parameter.

According to an embodiment of the present application, detecting the state parameter of the ultrasonic transducer in real time includes: detecting the voltage across the ultrasonic transducer in real time as the state parameter.

S1402. Output a driving signal to the excitation circuit according to the state parameter of the ultrasonic transducer, so that the excitation circuit provides excitation power for the resonance circuit of the ultrasonic transducer.

According to an embodiment of the present application, a driving signal is output to the excitation circuit according to the temperature of the ultrasonic transducer, so that the excitation circuit provides an excitation power for the resonance circuit.

In this embodiment, in conjunction with FIG. 15 and FIG. 16, the driving apparatus 1000 involved in the driving control method of the ultrasonic vibrator according to the embodiment of the present application includes: a rectifier circuit 100, a resonance circuit 200, an excitation circuit 300, a temperature detection circuit 400, and a control circuit. 500.

Referring to FIG. 15, an input end of the rectifier circuit 100 is connected to an AC power source AC. The rectifier circuit 100 is configured to receive AC power output from the AC power source AC, and rectify the AC power to output pulsating DC power. The resonance circuit 200 includes an ultrasonic transducer Z1 and a resonance inductance L1 connected in series. The input terminal of the excitation circuit 300 is connected to the output terminal of the rectifier circuit 100, and the output terminal of the excitation circuit 300 is connected to the resonance circuit 200. The temperature detection circuit 400 is used to detect the temperature of the ultrasonic transducer Z1. The control circuit 50 is respectively connected to the control terminal of the excitation circuit 30 and the temperature detection circuit 400. The control circuit 500 is configured to output a driving signal to the excitation circuit 300 according to the temperature of the ultrasonic transducer Z1, so that the excitation circuit 300 converts the pulsating DC power to the AC power. To provide the excitation power for the resonance circuit 200.

In this embodiment, the ultrasonic transducer Z1 behaves as a capacitive impedance in electrical characteristics. After being connected in series with the resonant inductor L1, the resonant circuit 200 is formed, and the resonant frequency value is

The resonance circuit 200 has a frequency selection characteristic. When the frequency of the driving signal is the same as the resonance frequency of the resonance circuit 200, the ultrasonic transducer Z1 works in an optimal state and has a maximum output power.

However, the capacitive impedance of the ultrasonic transducer Z1 is not fixed, and its equivalent capacitance value will change with the change of temperature. For example, when the temperature of the ultrasonic transducer Z1 increases, the equivalent capacitance will decrease, according to the formula

The available resonance frequency increases, that is, the resonance frequency of the resonance circuit 200 has changed. If a fixed-frequency drive signal is still used, the frequency of the drive signal does not match the current resonance frequency of the resonance circuit 200, and the operation of the ultrasonic transducer Z1 The state deteriorates and the output power decreases.

In an embodiment of the present invention, as shown in FIG. 16, the rectifier circuit 100 is a bridge rectifier circuit, which is composed of diodes D1, D2, D3, and D4, and is used to convert AC power to pulsating DC power.

Further, as shown in FIG. 16, the control device 1000 may further include an impedance transformer T1. The primary side of the impedance transformer T1 is connected to the output terminal of the excitation circuit 300. The secondary side of the impedance transformer T1 is connected in series with the resonance circuit 200. . Among them, the setting of the impedance transformer T1 can transform the load of the ultrasonic transducer Z1 into an optimal load, which is convenient for the output power of the ultrasonic transducer Z1 to reach a preset rated power.

Further, as shown in FIG. 16, the control device 1000 may further include a first capacitor C1, one end of the first capacitor C1 is connected to the first pole of the output terminal of the rectifier circuit 10, and the other end of the first capacitor C2 is connected to the rectifier circuit 100. The second pole of the output terminal is connected, and the first capacitor C1 is used for smoothing the pulsating DC power.

In an embodiment of the present invention, the driving signal output by the control circuit 500 includes a first driving signal and a second driving signal, wherein the first driving signal and the second driving signal are complementary. It should be understood that the so-called complementary means that when any one of the first driving signal and the second driving signal is at a high level, the other signal is at a low level.

In this embodiment, as shown in FIG. 16, the control circuit 500 includes a half-bridge driver 51 and a controller 52. The output terminal of the half-bridge driver 51 is connected to the control terminal of the excitation circuit 300; the controller 52 has a first PWM pin PWMP, a second PWM pin PWMN, and an AD pin Adc, and the first PWM pin PWMP and the half-bridge The first input terminal of the driver 51 is connected, the second PWM pin PWMN is connected to the second input terminal of the half-bridge driver 51, the AD pin Adc is connected to the temperature detection circuit 400, and the controller 400 outputs the first through the first PWM pin PWMP A control signal, and output a second control signal through the second PWM pin PWMN, so that the half-bridge driver 51 generates the first driving signal and the second driving signal correspondingly according to the first control signal and the second control signal, wherein, The first control signal and the second control signal are complementary.

Further, as shown in FIG. 16, the excitation circuit 300 includes a first switching transistor Q1, a second capacitor C2, a second switching transistor Q2, and a third capacitor C3.

The gate of the first switching transistor Q1 is connected to the first output terminal of the half-bridge driver 51, and the drain of the first switching transistor Q1 is connected to the first electrode of the output terminal of the rectifier circuit 100 and forms a first node a. The source of a switching transistor Q1 is connected to one end of the primary side of the impedance transformer T1 and forms a second node b. The first end of the second capacitor C2 is connected to the first node a, and the other end of the second capacitor C2 is connected to the other end of the primary side of the impedance transformer T1 and forms a third node c. The gate of the second switch Q2 is connected to the second output of the half-bridge driver 51, the drain of the second switch Q2 is connected to the second node b, and the source of the second switch Q2 is connected to the output of the rectifier circuit 100. The second pole is connected and forms a fourth node d. One end of the third capacitor C3 is connected to the third node c, and the other end of the third capacitor C3 is connected to the fourth node d.

In this embodiment, the gate of the first switch Q1 and the gate of the second switch Q2 are the control terminals of the excitation circuit 300. The half-bridge driver 51 outputs the first driving signal through the first output terminal, and the half-bridge driver 51 passes through The second output terminal outputs a second driving signal.

Furthermore, as shown in FIG. 16, the temperature detection circuit 400 includes a thermistor RT1 and a sampling resistor R1. Among them, the thermistor RT1 is set close to the ultrasonic transducer Z1, one end of the thermistor RT1 is connected to a preset power source Vcc (such as + 5V power source), and the other end of the thermistor RT1 is connected to the AD pin Adc of the controller 400. Connected. One end of the sampling resistor R1 is connected to the other end of the thermistor RT1, and the other end of the sampling resistor R1 is grounded. Alternatively, referring to FIG. 16, the controller 52 may share a preset power source Vcc with the temperature detection circuit 400.

Specifically, the thermistor RT1 is closely attached to the ultrasonic transducer Z1, and is used to sense the temperature of the ultrasonic transducer Z1 and convert the temperature amount into a resistance amount; the sampling resistor R1 is used to convert the resistance amount to a voltage amount, and The output signal is sent to the AD pin Adc of the controller 52.

In this embodiment, the controller 52 is specifically configured to read the AD value inputted from the AD pin of the AD pin; calculate the PWM value according to the AD value, and input the PWM value to the register of the PWM generator of the controller 52, and according to the PWM value A first control signal and a second control signal are output.

It should be noted that a preset PWM value may be pre-stored in the register, so that when the temperature of the ultrasonic transducer Z1 is not detected, the PWM generator outputs a first control signal and a second control signal according to the preset PWM value.

Specifically, the thermistor RT1 is an NTC thermistor with a negative temperature characteristic, and the material constant B value is 3950. The corresponding resistance value at 25 ° C is 100KΩ; the resistance value of the sampling resistor R1 is 5.1KΩ; the clock of the controller 52 The frequency is 16MHz, the preset power source uses + 5V power source, and the AD value has a resolution of 10 bits.

The controller 52 calculates the PWM value according to the following formula (1):

Among them, a is the AD value, U is the voltage value, R _t is the resistance value corresponding to the current temperature t, R ₀ is the resistance value corresponding to the preset temperature t0, B is the material constant of the thermistor RT1, f is the frequency, and P Is the PWM value, and Fosc is the clock frequency of the controller 52. It should be understood that both R ₀ and t0 are known quantities, for example, t0 is 0 ° C, R ₀ is the resistance value of the thermistor RT1 at 0 ° C; t0 is 25 ° C, and R ₀ is the thermistor RT1 Resistance at 25 ° C.

Of course, the temperature detection circuit 400 may also use other temperature sensing elements, such as a thermocouple, to detect the temperature of the ultrasonic transducer Z1.

The operation principle of the driving device 1000 according to the embodiment of the present invention is described below with reference to FIGS. 16 to 18.

Referring to FIG. 16, the controller 52 outputs two complementary PWM square wave signals (that is, the first control signal and the second control signal). The high-level amplitude of the square-wave signal is 5V, and the low-level amplitude is 0V. After the half-bridge driver 51, a square wave signal with a high level of 15V and a low level of 0V is converted and output to the gates of the first switch Q1 and the gate of the second switch Q2, respectively.

When the PWMP pin of the controller 52 outputs a high level of 5V, the PWMN pin outputs a low level of 0V. After the half-bridge driver 51, the voltage between the GS of the first switch Q1 is 15V, and the first switch Q1 turns on. ON, the second switch Q2 is turned off, the DS pin of the first switch Q1 is short-circuited, the DS pin of the first switch Q1, the primary side of the impedance transformer T1, and the second capacitor C2 form a loop to connect the second capacitor C2 performs charging and discharging. The voltage of the primary winding (that is, the primary side) of the impedance transformer T1 is positive left, right, and negative, and the secondary winding (that is, the secondary side) outputs a positive left, right, and negative voltage to power the resonance circuit 200.

When the PWMP pin of the controller 52 outputs a low level of 0V, the PWMN pin outputs a low level of 5V. After passing through the half-bridge driver 51, the voltage between the GS of the second switch Q2 is 15V, and the second switch Q2 turns on. ON, the first switch Q1 is turned off, so that the DS pin of the second switch Q2 is short-circuited, the DS pin of the second switch Q2, the primary side of the impedance transformer T1 and the third capacitor C3 form a loop to The capacitor C3 is charged and discharged. The primary winding voltage of the impedance transformer T1 is left-negative-right-positive, and the secondary winding outputs a left-negative-right-positive voltage to power the resonance circuit 200.

The thermistor RT1 is set close to the ultrasonic transducer Z1 and is used to sense the temperature change of the ultrasonic transducer Z1 and send the temperature change data to the controller 52. The controller 52 receives the temperature change data and uses a preset function The conversion type (that is, the above formula (1)) calculates the PWM value and sends it to the register of the internal PWM generator of the controller 52. The corresponding pins are output through the PWM pins (including the first PWM pin PWMP and the second PWM pin PWMN). The PWM signal drives the resonance circuit 200 after passing through the half-bridge driver 51, wherein the frequency of the PWM signal is consistent with the resonance frequency value of the resonance circuit 200.

Specifically, as shown in FIG. 17, when the temperature of the ultrasonic transducer Z1 increases, the equivalent capacitance value decreases, and the resonance frequency of the resonance circuit 200 increases. The temperature of the ultrasonic transducer Z1 rises and is transmitted to the thermistor RT1. After the controller 52 detects the temperature value change, it calculates and outputs the corresponding high-frequency PWM value through the above formula (1), so that the PWM output by the controller 52 The frequency of the signal is consistent with the current resonance frequency value of the resonance circuit 200.

When the temperature of the ultrasonic transducer Z1 decreases, the equivalent capacitance value increases, and the resonance frequency of the resonance circuit 200 decreases. The temperature of the ultrasonic transducer Z1 drops and is transmitted to the thermistor RT1. After the controller 52 detects the temperature value change, the corresponding low-frequency PWM value is calculated and output by the above formula (1), so that the PWM signal output by the controller 52 The frequency of is consistent with the current resonance frequency value of the resonance circuit 200.

Thereby, automatic tracking of the frequency of the resonance circuit is achieved.

For example, when the cooking appliance is working, the ultrasonic transducer Z1 will produce mechanical vibration. The mechanical vibration will cause the temperature of the ultrasonic transducer Z1 to increase. After the temperature increases, the LC resonance frequency of the ultrasonic transducer will occur. Variety. Assume that the temperature of the ultrasonic transducer Z1 suddenly rises to a certain temperature. As shown in FIG. 18, the controller 52 performs the following steps:

S1, the controller reads the AD value, if the obtained temperature AD value a = 230;

S2 through AD-voltage function

Calculate the voltage value U = 1.1234V;

S3, via voltage-resistance function

Calculated resistance value R _t = 17.5983KΩ;

S4 through resistance-temperature function

Calculated temperature value t = 70 ℃;

S5. Calculate the frequency value f = 30KHz through the temperature-frequency function relationship f = 0.04t + 27.2;

S6, through frequency-PWM value function

Calculate the PWM value P = 267;

S7. Send the value 267 to the register of the PWM generator.

Further, after the execution of step S7, the two PWM pins of the controller 52 output a square wave signal with a frequency of 30 KHz, and output a 30 KHz AC voltage to drive the LC resonance circuit after passing through the half-bridge driver 52. As can be seen from FIG. 17, The driving frequency at this time is consistent with the natural resonance frequency of the resonance circuit 200, and the ultrasonic transducer Z1 works in an optimal state, thereby achieving automatic frequency tracking.

Similarly, when the temperature of the ultrasonic transducer Z1 is 50 ° C, the PWM value output to the register of the PWM generator can be calculated to be 274. At this time, the frequency of the PWM signal output by the controller 52 is 29.2KHz. It can be seen that at this time, the driving frequency of the controller 52 is consistent with the current resonance frequency of the resonance circuit 200, and the ultrasonic transducer Z1 works in an optimal state.

According to an embodiment of the present application, a driving signal is output to the excitation circuit according to a voltage across the ultrasonic transducer, so that the excitation circuit provides an excitation power for the resonance circuit.

In this embodiment, in conjunction with FIG. 19 and FIG. 20, the driving device 10 involved in the method for driving and controlling the ultrasonic oscillator according to the embodiment of the present application includes a rectifier circuit 1, a resonance circuit 2, an excitation circuit 3, a voltage detection circuit 4, and a control circuit 5. .

Referring to FIG. 19, an input end of the rectifier circuit 1 is connected to an AC power source AC. The rectifier circuit 1 is configured to receive AC power output from the AC power source AC and rectify the AC power to output pulsating DC power. The resonance circuit 2 includes an ultrasonic transducer Z1 and a resonance inductance L1 connected in series. The input terminal of the excitation circuit 3 is connected to the output terminal of the rectifier circuit 1, and the output terminal of the excitation circuit 3 is connected to the resonance circuit 2. The voltage detection circuit 4 is used to detect the voltage of the ultrasonic transducer Z1. The control circuit 5 is respectively connected to the control terminal of the excitation circuit 3 and the voltage detection circuit 4. The control circuit 5 is configured to output a driving signal to the excitation circuit 3 according to the voltage of the ultrasonic transducer Z1, so that the excitation circuit 3 converts the pulsating DC power to the AC power. To provide excitation power for the resonance circuit 2.

In this embodiment, the ultrasonic transducer Z1 behaves as a capacitive impedance in electrical characteristics. After being connected in series with the resonant inductor L1, the resonant circuit 2 is formed, and the resonant frequency value is

The resonance circuit 2 has a frequency selection characteristic. When the frequency of the driving signal is the same as the resonance frequency of the resonance circuit 2, the ultrasonic transducer Z1 works in an optimal state and has a maximum output power. As shown in FIG. 21, when the frequency f of the driving signal output by the control circuit 5 is closer to the resonance frequency F0 of the resonance circuit 2, the output power is larger; the farther the frequency f is from the resonance frequency F0, the smaller the output power is.

In specific implementation, in order to prevent the frequency f from falling into a frequency region lower than F0, in the internal software design of the control circuit 5, a minimum frequency value f2 can be set in the PWM generator control strategy. As shown in FIG. 20, the PWM generator The resulting frequency is greater than or equal to f2.

However, the capacitive impedance of the ultrasonic transducer Z1 is not fixed, and its equivalent capacitance value will change with factors such as temperature, environment, vibration time, and aging of vibration system components. After the equivalent capacitance value C changes, follow the formula

It can be found that the resonance frequency of the resonance circuit drifts. This drift will increase the reactive component of the resonance circuit and increase the reactive power. If a fixed-frequency drive signal is still used, the frequency of the drive signal is different from the current resonance frequency of the resonance circuit Matching, the working state of the ultrasonic transducer Z1 becomes worse, which greatly shortens the service life of the ultrasonic transducer Z1.

When the resonant circuit composed of the ultrasonic transducer Z1 and the resonant inductor L1 works, the larger the output power of the ultrasonic transducer Z1 and the larger the current flowing through the resonant circuit, the larger the voltage across the ultrasonic transducer Z1. Therefore, the control device of the embodiment of the present invention detects the voltage across the ultrasonic transducer through the voltage detection circuit, and can indirectly detect the output power of the ultrasonic transducer Z1, and then outputs a corresponding driving signal to the excitation according to the voltage through the control circuit. The circuit is used to provide excitation power to the resonance circuit, and the frequency of the driving signal is consistent with the current resonance frequency of the resonance circuit, so that the ultrasonic transducer Z1 can work in an optimal state, thereby improving the cooking effect of the cooking appliance.

In an embodiment of the present invention, as shown in FIG. 20, the rectifier circuit 1 is a bridge rectifier circuit, which is composed of diodes D1, D2, D3, and D4, and is used to convert AC power to pulsating DC power.

Further, as shown in FIG. 20, the driving device 10 may further include an impedance transformer T1, a primary side of the impedance transformer T1 is connected to the output terminal of the excitation circuit 3, and a secondary side of the impedance transformer T1 is connected in series with the resonance circuit 2 . The setting of the impedance transformer T1 can transform the load of the ultrasonic transducer Z1 into an optimal load, which is convenient for the output power of the ultrasonic transducer Z1 to reach a preset rated power.

Further, as shown in FIG. 20, the control device 10 may further include a first capacitor C1, one end of the first capacitor C1 is connected to the first pole of the output terminal of the rectifier circuit 1, and the other end of the first capacitor C2 is connected to the rectifier circuit 1. The second pole of the output terminal is connected, and the first capacitor C1 is used for smoothing the pulsating DC power.

In an embodiment of the present invention, the driving signal output by the control circuit 5 includes a first driving signal and a second driving signal, wherein the first driving signal and the second driving signal are complementary. It should be understood that the so-called complementary means that when any one of the first driving signal and the second driving signal is at a high level, the other signal is at a low level.

In this embodiment, as shown in FIG. 20, the control circuit 5 includes a half-bridge driver 501 and a controller 502. The output terminal of the half-bridge driver 501 is connected to the control terminal of the excitation circuit 3; the controller 502 has a first PWM pin PWMP, a second PWM pin PWMN, and an AD pin Vad, and the first PWM pin PWMP and the half-bridge The first input terminal of the driver 501 is connected, the second PWM pin PWMN is connected to the second input terminal of the half-bridge driver 501, the AD pin Vad is connected to the voltage detection circuit 4, and the controller 502 outputs the first through the first PWM pin PWMP A control signal, and output a second control signal through the second PWM pin PWMN, so that the half-bridge driver 501 generates the first driving signal and the second driving signal corresponding to the first control signal and the second control signal, wherein, The first control signal and the second control signal are complementary.

Further, as shown in FIG. 20, the excitation circuit 3 includes a first switching transistor Q1, a second capacitor C2, a second switching transistor Q2, and a third capacitor C3.

The gate of the first switching transistor Q1 is connected to the first output terminal of the half-bridge driver 501, and the drain of the first switching transistor Q1 is connected to the first electrode of the output terminal of the rectifier circuit 1, and forms a first node a. The source of a switching transistor Q1 is connected to one end of the primary side of the impedance transformer T1 and forms a second node b. The first end of the second capacitor C2 is connected to the first node a, and the other end of the second capacitor C2 is connected to the other end of the primary side of the impedance transformer T1 and forms a third node c. The gate of the second switch Q2 is connected to the second output of the half-bridge driver 501, the drain of the second switch Q2 is connected to the second node b, and the source of the second switch Q2 is connected to the output of the rectifier circuit 1. The second pole is connected and forms a fourth node d. One end of the third capacitor C3 is connected to the third node c, and the other end of the third capacitor C3 is connected to the fourth node d.

In this embodiment, the gate of the first switching transistor Q1 and the gate of the second switching transistor Q2 are the control terminals of the excitation circuit 3. The half-bridge driver 501 outputs the first driving signal through the first output terminal, and the half-bridge driver 501 passes through The second output terminal outputs a second driving signal.

Furthermore, as shown in FIG. 20, the voltage detection circuit 4 includes a first inductor L2, a first diode D5, a first resistor R1, and a fourth capacitor C4. The first inductor L2 and the resonant inductor L1 form a mutual inductance coil LT1, and one end of the first inductor L2 is grounded; the anode of the first diode D5 is connected to the other end of the first inductor L2, and the cathode of the first diode D5 is connected to The AD pin Vad of the controller 52 is connected; one end of the first resistor R1 is connected to the cathode of the first diode D5, and the other end of the first resistor R1 is grounded; the fourth capacitor C4 is connected in parallel with the first resistor R1.

Specifically, referring to FIG. 20, when there is a voltage on the resonant inductor L1, the first inductor L2 serves as a secondary winding of the mutual inductance coil LT1, and a mutual inductance voltage can be generated thereon, and the mutual inductance voltage is an AC voltage. The AC voltage is rectified by the first diode D5, and filtered by the fourth capacitor C4, and a smooth DC level signal is output and sent to the AD pin Vad of the controller 502.

Of course, the voltage detection circuit 4 may also adopt other circuits, such as directly leading out connection lines at both ends of the ultrasonic transducer Z1, and connecting the voltage sensor between the connection lines.

In one embodiment of the present invention, the controller 502 includes a PWM generator, and the PWM generator includes a register. The controller 502 is specifically configured to adjust the PWM value in the register according to the voltage across the ultrasonic transducer Z1, and then according to the adjusted The PWM value outputs a first control signal and a second control signal.

Wherein, the controller 502 is specifically used to determine whether the voltage across the ultrasonic transducer Z1 is greater than a preset voltage when adjusting the PWM value in the register based on the voltage across the ultrasonic transducer Z1; if the voltage across the ultrasonic transducer Z1 is greater than a preset voltage; If the voltage is equal to the preset voltage, the PWM value in the register remains unchanged. If the voltage across the ultrasonic transducer Z1 is greater than the preset voltage, the PWM value and the first preset value are compared when the PWM value is greater than the preset minimum value. Perform the difference operation and keep the PWM value unchanged when the PWM value is less than or equal to the preset minimum value; if the voltage across the ultrasonic transducer Z1 is less than the preset voltage, when the PWM value is less than the preset maximum value, The PWM value is summed with the second preset value, and the PWM value is kept unchanged when the PWM value is greater than or equal to the preset maximum value.

In this embodiment, the preset voltage, the preset minimum value, and the preset maximum value can be set according to the electrical parameters of the ultrasonic transducer Z1 and the resonance inductance L1. Both the first preset value and the second preset value are greater than 0, and the values of both can be set as required. For example, if the first preset value is equal to the second preset value, both are 1. Of course, the first preset value The set value may not be equal to the second preset value.

It should be noted that a preset PWM value may be pre-stored in the register, so that when the voltage across the ultrasonic transducer Z1 is not detected, the PWM generator outputs a first control signal and a second control signal according to the preset PWM value. .

The working principle of the driving device 10 according to the embodiment of the present invention is described below with reference to FIGS. 20 to 22.

Referring to FIG. 20, the controller 502 outputs two complementary PWM square wave signals (that is, the first control signal and the second control signal). The high-level amplitude of the square-wave signal is 5V, and the low-level amplitude is 0V. After the half-bridge driver 501, a square wave signal with a high level of 15V and a low level of 0V is converted and output to the gates of the first switch Q1 and the gate of the second switch Q2, respectively.

When the PWMP pin of the controller 502 outputs a high level of 5V, the PWMN pin outputs a low level of 0V. After the half-bridge driver 501, the voltage between the GS of the first switch Q1 is 15V, and the first switch Q1 turns on. ON, the second switch Q2 is turned off, the DS pin of the first switch Q1 is short-circuited, the DS pin of the first switch Q1, the primary side of the impedance transformer T1, and the second capacitor C2 form a loop to connect the second capacitor C2 performs charging and discharging. The voltage of the primary winding (that is, the primary side) of the impedance transformer T1 is positive left and right negative, and the secondary winding (that is, the secondary side) outputs a positive left and right negative voltage to power the resonance circuit 2.

When the PWMP pin of the controller 502 outputs a low level of 0V, the PWMN pin outputs a low level of 5V. After passing through the half-bridge driver 501, the voltage between the GS of the second switch Q2 is 15V, and the second switch Q2 turns on. ON, the first switch Q1 is turned off, so that the DS pin of the second switch Q2 is short-circuited, the DS pin of the second switch Q2, the primary side of the impedance transformer T1 and the third capacitor C3 form a loop to The capacitor C3 is charged and discharged. The primary winding voltage of the impedance transformer T1 is left-negative-right-positive, and the secondary winding outputs a left-negative-right-positive voltage to power the resonance circuit 2.

In one embodiment, when the cooking appliance is operating, the PWM generator of the controller 502 outputs a PWM square wave signal of a certain frequency, and the AC signal of this frequency is output by the half-bridge driver 501 to drive the ultrasonic transducer Z1 and the resonant inductor L1. The resonance circuit 2. Detect the voltage across the primary winding (resonant inductance L1) through the secondary winding (ie, the first inductance L2) of the mutual inductance coil LT1, and rectify and filter the first diode D5 and the fourth capacitor C4 to output a smooth DC voltage. The signal is sent to the Vad pin of the controller 502, and the controller 502 periodically starts the AD analog-to-digital conversion to read the AD value of the pin.

Further, if the AD value of the current Vad pin is equal to the preset AD value, the current PWM value in the register is kept unchanged. If the AD value of the current Vad pin is greater than the preset AD value, further determine the relationship between the current PWM value and the preset minimum value; if the current PWM value is greater than the preset minimum value, subtract 1 from the current PWM value; otherwise, keep The current PWM value does not change. If the current AD value of the Vad pin is less than the preset AD value, the relationship between the current PWM value and the preset maximum value is further judged. If the current PWM value is less than the preset maximum value, the current PWM value is incremented by one; otherwise, it is maintained. The current PWM value does not change.

As an example, the clock frequency Fosc of the controller 502 is 16 MHz, and the frequency at which the PWM pin of the controller 502 outputs the first control signal and the second control signal f = Fosc / 2x, where x is the PWM value in the register. The preset AD value is 200, the preset minimum value is 228, and the preset maximum value is 320. For example, when the PWM value is 286, the frequency at which the PWM pin of the controller 502 outputs the first control signal and the second control signal f = 16000 / (2 * 286) = 28KHz. At this time, the output power of the ultrasonic transducer Z1 is 50. Tile, as shown in Figure 22.

In this example, the timer program in the controller 502 will set the 10 milliseconds flag every 10 milliseconds. The controller 502 performs the following steps:

S1. Determine whether the 10 milliseconds flag bit is set to 1. If not, return to perform the next cycle judgment. If yes, execute step E1.

E1, clear the 10 ms flag bit;

E2, start the AD analog-to-digital conversion to read the AD value of the pin Vad;

S2. Determine whether the AD value is equal to a preset AD value.

If the AD value is 200, which is equal to the preset AD value, it means that the frequency of the PWM square wave output by the current controller is consistent with the resonance frequency of the resonant circuit. There is no need to adjust the frequency of the PWM square wave output by the controller and keep the current PWM value 286 does not change, and returns to the next cycle of judgment.

Due to the influence of temperature or other environmental factors, the equivalent capacitance value of the ultrasonic transducer Z1 will change, which will cause the resonance frequency F0 of the resonance circuit 2 to change.

As shown in FIG. 21, before the change, the characteristic curve of the resonance circuit 2 is an SV1 curve, and its resonance frequency is F0. The PWM value in the register of the PWM generator of the controller 502 is 286. According to the formula f = Fosc / 2x, the PWM The frequency of the foot output signal is equal to 28KHz, that is, the frequency f2 shown in FIG. 21, the power output by the ultrasonic transducer Z1 is 50W, and the AD value obtained by analog-to-digital conversion of the Vad pin of the controller 502 is 200.

As shown in Figure 21, after the change, the resonance frequency of the resonance circuit 2 drifts to F0 ', and its characteristic curve is the SV2 curve. At this time, if the PWM pin of the controller 502 still outputs an output signal at a frequency of 28KHz, as shown in Figure 21 At the frequency f2 shown, the output power of the ultrasonic transducer Z1 is increased to 53W, and the AD value is increased from the original 200 to 205 at this time.

S3. When the AD value is not equal to the preset AD value, determine whether the AD value is greater than the preset AD value;

S4. If the AD value is greater than a preset AD value, further determine whether the current PWM value is greater than a preset minimum value;

E3, if the current PWM value is greater than the preset minimum value, subtract 1 from the current PWM value;

Wherein, if the current PWM value is less than or equal to the preset minimum value, it returns to the next cycle judgment.

S5. If the AD value is less than a preset AD value, further determine whether the current PWM value is less than a preset maximum value;

E3, if the current PWM value is less than the preset maximum value, add 1 to the current PWM value;

Wherein, if the current PWM value is greater than or equal to a preset maximum value, it returns to judge the next cycle.

Repeat the process.

According to the above equation f = Fosc / 2x, the smaller the PWM value, the higher the frequency of the output signal of the controller 52, as shown in FIG. 21, when the frequency of the output signal of the controller 52 reaches f2 ', the changed ultrasonic transducer The output power of Z1 is reduced to 50W, and the ultrasonic transducer Z1 returns to the best working state, thereby realizing the automatic tracking of the frequency.

FIG. 23 is a schematic block diagram of a driving control device for an ultrasonic transducer according to an embodiment of the present application. As shown in FIG. 23, the driving control device for the ultrasonic vibrator includes a first detection module 101 and a control module 102.

The first detection module 101 is configured to obtain the state parameters of the resonance circuit where the ultrasonic oscillator is located; and the control module 102 is configured to adjust the frequency of the AC control signal of the resonance circuit according to the state parameters.

According to an embodiment of the present application, the first detection module 101 is configured to obtain a current phase signal corresponding to the AC current signal of the resonance circuit where the ultrasonic oscillator is located, and the phase of the current phase signal is consistent with the phase of the AC current signal; the control module 102 is configured to calculate The phase difference between the phase of the AC control signal and the phase of the current phase signal input to the resonance circuit, the frequency of the AC control signal is adjusted according to the difference, and the adjusted AC control signal is output.

According to an embodiment of the present application, the first detection module 101 is configured to obtain an AC current signal of a resonance circuit where an ultrasonic oscillator is located, convert the AC current signal into an AC voltage signal, and rectify and filter the AC voltage signal to obtain a DC voltage. Signal; the control module 102 is configured to adjust the frequency of the AC control signal input to the resonance circuit according to the DC voltage signal, and output the AC control signal. According to an embodiment of the present application, the first detection module 101 includes: a current sampling module for acquiring an AC current signal and converting the AC current signal into an AC voltage signal; an amplitude limiting module for converting the amplitude of the AC voltage signal The value is limited within a set amplitude range to generate a limited AC voltage signal; a reference voltage module is used to generate a reference voltage signal; a phase comparison module is used to generate a current phase signal according to the limited AC voltage signal and the reference voltage signal.

According to an embodiment of the present application, the current sampling module includes: a current transformer for converting an input AC current signal of a first amplitude into an AC current signal of a second amplitude, and the second amplitude is smaller than the first amplitude And output the AC current signal of the second amplitude; the load resistance, the load resistance and the current transformer are connected in parallel, and are used to convert the AC current signal of the second amplitude into an AC voltage signal.

According to an embodiment of the present application, the amplitude limiting module includes: a current limiting resistor, a first end of the current limiting resistor is connected to the first output terminal of the current sampling module, and a second end of the current limiting resistor is positively connected to the input of the phase comparison module. The first diode, the anode of the first diode is connected to the input positive terminal of the phase comparison module, the cathode of the first diode is connected to the input negative terminal of the phase comparison module and the first output of the current sampling module, respectively The second diode, the anode of the second diode is connected to the negative input terminal of the phase comparison module, and the cathode of the second diode is connected to the positive input terminal of the phase comparison module.

According to an embodiment of the present application, the reference voltage module includes: a first voltage dividing resistor, a first end of the first voltage dividing resistor being connected to a first DC power source; a second voltage dividing resistor, a first voltage dividing resistor Terminals are respectively connected to the second terminal of the first voltage dividing resistor and the input negative terminal of the phase comparison module, and the second terminal of the second voltage dividing resistor is grounded; the filter capacitor, the first terminal of the filter capacitor and the input negative terminal of the phase comparison module Connected, the second end of the filter capacitor is grounded.

According to an embodiment of the present application, the phase comparison module includes: a phase comparator, an in-phase input terminal of the phase comparator is connected to a first output terminal of the amplitude limit module, and an inverting input terminal of the phase comparator is respectively connected to the amplitude limit module. The second output of the

According to an embodiment of the present application, the first detection module further includes a rectification and filtering module, configured to rectify and filter the AC voltage signal to obtain a DC voltage signal.

According to an embodiment of the present application, the rectifying and filtering module includes: a rectifying diode for rectifying the AC voltage signal to obtain a pulsating DC voltage signal; and a filtering capacitor for filtering the pulsating DC voltage signal to obtain smoothness. DC voltage signal.

It should be noted that the foregoing explanation of the embodiment of the method for driving and controlling the ultrasonic oscillator is also applicable to the device for controlling and driving the ultrasonic oscillator in this embodiment, and details are not described herein again.

According to the driving control device for an ultrasonic oscillator provided in the embodiment of the present application, the state parameter of the resonance circuit where the ultrasonic oscillator is located can be obtained through the first detection module, and the frequency of the AC control signal of the resonance circuit can be adjusted by the control module according to the state parameter. Therefore, by monitoring the current in the LC resonant circuit of the ultrasonic transducer or the phase of the current in the LC resonant circuit of the ultrasonic transducer, the controller has the ability to obtain the working state of the ultrasonic transducer, thereby adjusting the frequency of the PWM signal, thereby The new PWM frequency is consistent with the natural frequency of the LC after the drift, and the ultrasonic transducer works in the best state, realizing automatic frequency tracking, effectively improving product reliability and increasing product life.

FIG. 24 is a schematic block diagram of another driving control device for an ultrasonic transducer according to an embodiment of the present application. As shown in FIG. 24, the driving control device for the ultrasonic transducer includes: a second detection module 201 for detecting a state parameter of the ultrasonic transducer in real time; and a driving module 202 for outputting a driving signal to the ultrasonic transducer according to the state parameter of the ultrasonic transducer. Excitation circuit, so that the excitation circuit provides excitation power for the resonance circuit of the ultrasonic transducer.

According to the driving control device of the ultrasonic transducer provided in the embodiment of the present application, the state parameter of the ultrasonic transducer can be detected in real time by the second detection module, and the driving module outputs a driving signal to the excitation circuit according to the state parameter of the ultrasonic transducer through the driving module. The excitation circuit is provided to provide the excitation power for the resonance circuit of the ultrasonic transducer. Therefore, by detecting a change in the voltage across the ultrasonic transducer or a change in the temperature of the ultrasonic transducer, the output frequency of the control signal is adjusted so that it is consistent with the resonance frequency of the current resonant circuit, so that the ultrasonic transducer works. In the best state, the automatic tracking of the frequency is realized, and the product life is effectively extended.

An embodiment of the present application provides a cooking appliance, which includes an ultrasonic vibrator and the driving control device of the ultrasonic vibrator of the embodiment shown in FIG. 23 or the driving control device of the ultrasonic vibrator of the embodiment shown in FIG. 24.

According to the cooking appliance provided in the embodiment of the present application, through the above-mentioned driving control device of the ultrasonic oscillator, the state parameter of the resonance circuit where the ultrasonic oscillator is located can be obtained through the first detection module, and the AC module of the resonance circuit is adjusted by the control module according to the state parameter. The frequency of the signal. Therefore, by monitoring the current in the LC resonant circuit of the ultrasonic transducer or the phase of the current in the LC resonant circuit of the ultrasonic transducer, the controller has the ability to obtain the working state of the ultrasonic transducer, thereby adjusting the frequency of the PWM signal, thereby Make the new PWM frequency consistent with the natural frequency of the LC after the drift, and the ultrasonic transducer works at the best state to achieve automatic frequency tracking, effectively improve the reliability of the product and increase the product life; it can also be detected in real time by the second detection module The state parameter of the ultrasonic transducer, and the driving module outputs a driving signal to the excitation circuit according to the state parameter of the ultrasonic transducer, so that the excitation circuit provides excitation power for the resonance circuit of the ultrasonic transducer. Therefore, by detecting a change in the voltage across the ultrasonic transducer or a change in the temperature of the ultrasonic transducer, the output frequency of the control signal is adjusted so that it is consistent with the resonance frequency of the current resonant circuit, so that the ultrasonic transducer works. In the best state, the automatic tracking of the frequency is realized, and the product life is effectively extended. .

An embodiment of the present application provides an electronic device including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the ultrasonic vibrator of the embodiment shown in FIG. 1 is implemented. Or a driving control method for an ultrasonic transducer according to the embodiment shown in FIG. 14.

The embodiment of the present application proposes a non-transitory computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the method for driving and controlling the ultrasonic vibrator of the embodiment shown in FIG. 1 is implemented, or The driving control method for the ultrasonic transducer of the embodiment shown in FIG. 14 described above.

In the description of this application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Rear "," left "," right "," vertical "," horizontal "," top "," bottom "," inside "," outside "," clockwise "," counterclockwise "," axial ", The directions or positional relationships indicated by "radial" and "circumferential" are based on the positional or positional relationships shown in the drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying the device or element referred to. It must have a specific orientation and be constructed and operated in a specific orientation, so it cannot be understood as a limitation on this application.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality" is at least two, for example, two, three, etc., unless it is specifically and specifically defined otherwise.

In this application, the terms "installation," "connected," "connected," and "fixed" should be broadly understood unless otherwise specified and limited. For example, they can be fixed connections or removable connections. , Or integrated; it can be mechanical or electrical; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of the two elements or the interaction between the two elements, unless otherwise specified The limit. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

In this application, unless explicitly stated and defined otherwise, the first feature "on" or "down" of the second feature may be the first and second features in direct contact, or the first and second features indirectly through an intermediate medium. contact. Moreover, the first feature is "above", "above", and "above" the second feature. The first feature is directly above or obliquely above the second feature, or only indicates that the first feature is higher in level than the second feature. The first feature is "below", "below", and "below" of the second feature. The first feature may be directly below or obliquely below the second feature, or it may simply mean that the level of the first feature is smaller than the second feature.

In the description of this specification, the description with reference to the terms “one embodiment”, “some embodiments”, “examples”, “specific examples”, or “some examples” and the like means specific features described in conjunction with the embodiments or examples , Structure, material, or characteristic is included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. In addition, without any contradiction, those skilled in the art may combine and combine different embodiments or examples and features of the different embodiments or examples described in this specification.

Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limitations on the present application. Those skilled in the art may, within the scope of the present application, understand the above. Embodiments are subject to change, modification, substitution, and modification.

Claims

A driving control method for an ultrasonic vibrator is characterized in that it includes the following steps:

Obtaining state parameters of the resonance circuit where the ultrasonic oscillator is located;

Adjusting the frequency of the AC control signal of the resonance circuit according to the state parameter.
The driving control method according to claim 1, wherein the acquiring a state parameter of a resonance circuit where the ultrasonic oscillator is located comprises:

Acquiring a phase of an AC current signal of a resonance circuit where the ultrasonic oscillator is located;

Adjusting the frequency of the AC control signal of the resonance circuit according to the state parameter includes:

Calculating a difference between a phase of an AC control signal input to the resonance circuit and a phase of the AC current signal;

The frequency of the AC control signal is adjusted according to the difference.
The driving control method according to claim 1, wherein the adjusting the frequency of the AC control signal according to the difference comprises:

Identify that the difference is greater than or less than 0, then adjust the frequency;

It is recognized that the current difference is equal to 0, and then the frequency is kept unchanged.
The driving control method according to claim 2, wherein, when the identifying the difference is greater than or less than 0, adjusting the frequency comprises:

Identifying that the difference is less than 0, increasing the frequency;

If the difference is greater than 0, the frequency is reduced.
The driving control method according to claim 1, wherein the acquiring a state parameter of a resonance circuit where the ultrasonic oscillator is located comprises:

Obtaining a current of a resonance circuit where the ultrasonic oscillator is located;

Adjusting the frequency of the AC control signal of the resonance circuit according to the state parameter includes:

The frequency of the AC control signal input to the resonance circuit is adjusted according to the current.
The driving control method according to claim 5, wherein the adjusting the frequency of the AC control signal input to the resonance circuit according to the current comprises:

Identify that the current is greater than or less than a preset current threshold, then adjust the frequency, and the current threshold is less than the maximum resonance current of the resonance circuit;

It is recognized that the current is equal to the current threshold, and then the frequency is kept unchanged.
The driving control method according to claim 6, wherein the step of adjusting the frequency when the identifying that the current is greater than or less than a preset current threshold comprises:

Identify that the current is less than the current threshold, then increase the frequency;

If the current is greater than the current threshold, the frequency is reduced.
The drive control method according to claim 4 or 7, wherein:

The increasing the frequency includes: reducing the period of the AC control signal by one;

The reducing the frequency includes: increasing the period of the AC control signal by one.
A driving control method for an ultrasonic vibrator is characterized in that it includes the following steps:

Real-time detection of the state parameters of the ultrasonic transducer;

And outputting a driving signal to an excitation circuit according to a state parameter of the ultrasonic transducer, so that the excitation circuit provides an excitation power source for a resonance circuit of the ultrasonic transducer.
The driving control method according to claim 9, wherein the detecting the state parameters of the ultrasonic transducer in real time comprises:

The voltage across the ultrasonic transducer is detected in real time as the state parameter.
The driving control method according to claim 9, wherein the detecting the state parameters of the ultrasonic transducer in real time comprises:

The temperature of the ultrasonic transducer is detected in real time as the state parameter.
A driving control device for an ultrasonic vibrator, comprising:

A detection module, configured to obtain a state parameter of a resonance circuit where the ultrasonic oscillator is located;

A control module, configured to adjust the frequency of the AC control signal of the resonance circuit according to the state parameter.
The drive control device according to claim 12, wherein the detection module is configured to obtain a current phase signal corresponding to an AC current signal of a resonance circuit where the ultrasonic oscillator is located, and a phase of the current phase signal is equal to the phase of the current phase signal. The phases of the AC current signals are consistent;

A control module, configured to calculate a difference between the phase of the AC control signal input to the resonance circuit and the phase of the current phase signal, and adjust the frequency of the AC control signal according to the difference, and output the adjusted The AC control signal.
The drive control device according to claim 12, wherein the detection module is configured to obtain an AC current signal of a resonance circuit where the ultrasonic oscillator is located, and convert the AC current signal into an AC voltage signal, AC voltage signals are rectified and filtered to obtain DC voltage signals;

A control module is configured to adjust a frequency of an AC control signal input to the resonance circuit according to the DC voltage signal, and output the AC control signal.
The drive control device according to claim 12, wherein the detection module comprises:

A current sampling module, configured to obtain the AC current signal and convert the AC current signal into an AC voltage signal;

An amplitude limiting module, configured to limit the amplitude of the AC voltage signal within a set amplitude range to generate a limited AC voltage signal;

A reference voltage module for generating a reference voltage signal;

A phase comparison module is configured to generate the current phase signal according to the limited AC voltage signal and the reference voltage signal.
The drive control device according to claim 15, wherein the current sampling module comprises:

A current transformer, configured to convert the input AC current signal of a first amplitude to the AC current signal of a second amplitude, the second amplitude is smaller than the first amplitude, and output the The AC current signal of a second amplitude;

A load resistor, which is connected in parallel with the current transformer and is configured to convert the AC current signal of the second amplitude into the AC voltage signal.
The drive control device according to claim 15, wherein the amplitude limit module comprises:

A current limiting resistor, a first terminal of the current limiting resistor is connected to a first output terminal of the current sampling module, and a second terminal of the current limiting resistor is connected to an input positive terminal of the phase comparison module;

A first diode, an anode of the first diode is connected to an input positive terminal of the phase comparison module, and a cathode of the first diode is connected to an input negative terminal of the phase comparison module and the The first output terminal of the current sampling module is connected;

A second diode, an anode of the second diode is connected to an input negative terminal of the phase comparison module, and a cathode of the second diode is connected to an input positive terminal of the phase comparison module.
The drive control device according to claim 15, wherein the reference voltage module comprises:

A first voltage dividing resistor, and a first end of the first voltage dividing resistor is connected to a first DC power source;

A second voltage-dividing resistor, a first end of which is respectively connected to a second terminal of the first voltage-dividing resistor and an input negative terminal of the phase comparison module, The second end is grounded;

A filter capacitor, a first terminal of the filter capacitor is connected to an input negative terminal of the phase comparison module, and a second terminal of the filter capacitor is grounded.
The drive control device according to claim 15, wherein the phase comparison module comprises:

A phase comparator, a non-inverting input terminal of the phase comparator is connected to a first output terminal of the amplitude limit module, and an inverting input terminal of the phase comparator is respectively connected to a second output terminal of the amplitude limit module And connected to an output terminal of the reference voltage module.
The drive control device according to claim 12, wherein the first detection module further comprises:

A rectification and filtering module is configured to rectify and filter the AC voltage signal to obtain a DC voltage signal.
The drive control device according to claim 20, wherein the rectification and filtering module comprises:

A rectifier diode, configured to rectify the AC voltage signal to obtain the DC voltage signal that fluctuates;

A filter capacitor is configured to filter the fluctuated DC voltage signal to obtain a smooth DC voltage signal.
A driving control device for an ultrasonic vibrator, comprising:

A second detection module for detecting a state parameter of the ultrasonic transducer in real time;

A driving module is configured to output a driving signal to an excitation circuit according to a state parameter of the ultrasonic transducer, so that the excitation circuit provides an excitation power for a resonance circuit of the ultrasonic transducer.
A cooking appliance, comprising: an ultrasonic vibrator and the driving control device for an ultrasonic vibrator according to any one of claims 12 to 21, or the driving control device for an ultrasonic vibrator according to claim 22.
An electronic device, comprising: a memory, a processor, and a computer program stored on the memory and operable on the processor. When the processor executes the program, the method according to claim 1 is implemented. The driving control method for an ultrasonic transducer according to any one of -8, or the driving control method for an ultrasonic transducer according to any one of claims 9 to 11.
A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that when the program is executed by a processor, the driving control method for an ultrasonic transducer according to any one of claims 1 to 8, Or the driving control method for an ultrasonic transducer according to any one of claims 9-11.