Power ultrasonic synchronization tail wave absorption detection circuit

Abstract

The invention discloses a power ultrasonic synchronous tail wave absorption detection circuit which comprises a center tapped transformer TR1, MOS tube drivers U1, U2 and U3 and N-type MOS tubes Q1, Q2 and Q3. Input pins of the U1, the U2 and the U3 are respectively connected with a PWM1 excitation signal, a PWM2 excitation signal and a PWM3 excitation signal; output pins of the U1, the U2 and the U3 are respectively connected with damping matching resistors R1, R3 and R6 in series to grids of the N-type MOS tubes Q1, Q2 and Q3, and meanwhile, the grids of the Q1, the Q2 and the Q3 are respectively connected with peak absorption resistors R2, R4 and R7 in parallel; source electrodes of the Q1, the Q2 and the Q3 are grounded, and drain electrodes of the Q1 and the Q2 are respectively connected with two pins of a primary side of a center tapped transformer TR1; one pin of the secondary side of the TR1 is grounded after being connected in series with a matching inductor L1 and a piezoelectric transducer Y1, and the other pin of the secondary side of the TR1 is grounded; the diode D1, the tail wave absorption resistor R5 and the drain electrode of the Q3 are connected in series and then connected with the Y1 in parallel. The two ends of the Y1 are further connected with a detection circuit in parallel. According to the invention, the absorption problem of power ultrasonic tail waves can be solved, and the absorption effect can be monitored in real time.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ultrasonic emission, and particularly relates to a power ultrasonic synchronous tail wave absorption detection circuit. BACKGROUND

[0002] Transcranial focused ultrasound neuromodulation as a new type of non-invasive neuromodulation method, which utilizes the mechanical effect and biological effect of ultrasound, has the effects of changing the permeability of cell membranes, promoting the release of growth factors, promoting metabolism, accelerating blood circulation, relieving pain, etc. Irradiating brain tissue with a certain dose of ultrasound can treat depression, insomnia, Parkinson's disease, and Alzheimer's disease. The ultrasonic driving circuit is crucial for the generation and parameter control of the ultrasonic waveform.

[0003] At present, the ultrasonic wave still faces the interference of the tail wave after being emitted. Due to the existence of the tail wave, the ultrasonic energy cannot be accurately controlled, the treatment effect cannot reach the expectation, or the energy exceeds the FDA regulation, so the absorption of the tail wave of the ultrasonic driving circuit is crucial. Some researches have done some work to solve the problem of ultrasonic tail wave interference, For example, the Chinese patent document with the publication number CN118882543A discloses a multi-gear switchable impedance matching circuit and high-voltage pulse emission driving circuit for tail vibration elimination. The absorption circuit is applied to ultrasonic nondestructive testing. The absorption circuit used is an integrated chip, and is asynchronous absorption, which cannot cope with the tail wave absorption of high-power ultrasound, and asynchronous absorption may cause absorption delay, which cannot be absorbed at the moment of turning off the ultrasonic emission. At the same time, since there is no absorption effect monitoring in the absorption process, it is impossible to form a closed-loop feedback, and the scene where the absorption circuit fails cannot be located.

[0004] The Chinese patent document with the publication number CN116786390A discloses an ultrasonic transducer high-voltage driving circuit and method for suppressing ultrasonic wave tailing. Two high-voltage narrow pulse driving ultrasonic transducers with phase difference and unequal amplitude are used to achieve the purpose of weakening ultrasonic wave tailing according to the superposition principle.

[0005] In general, the existing tail wave absorption methods mainly have the following deficiencies: (1) The existing technology has low working voltage and small absorption energy. The current absorption circuit is controlled by an integrated chip, and the withstand voltage and overcurrent value are small, which cannot meet the application scenarios of high-voltage and large-current power ultrasound.

[0006] (2) The asynchronous absorption of the existing technology has absorption delay, which leads to absorption energy leakage. In the early stage of absorption, there is still waveform leakage, which causes the ultrasonic power supply to still have a driving waveform after being turned off.

[0007] (3) The prior art lacks absorption effect detection, cannot form a closed-loop feedback, and cannot intervene in the case of failure or performance degradation of the absorption circuit. SUMMARY

[0008] The application provides a power ultrasonic synchronous tail wave absorption detection circuit, which can solve the absorption problem of power ultrasonic tail waves, and simultaneously introduces effect detection to form a feedback mechanism and monitor the absorption effect in real time.

[0009] A power ultrasonic synchronous tail wave absorption detection circuit, comprising a center-tapped transformer TR1, MOS tube drivers U1, U2, and U3, and N-type MOS tubes Q1, Q2, and Q3. The input pins of the MOS tube drivers U1, U2, and U3 are connected to PWM1 excitation signals, PWM2 excitation signals, and PWM3 excitation signals, respectively; the output pins of the MOS tube drivers U1, U2, and U3 are connected in series to damping matching resistors R1, R3, and R6 to the gates of the N-type MOS tubes Q1, Q2, and Q3, and, at the same time, the gates of the N-type MOS tubes Q1, Q2, and Q3 are connected in parallel to peak absorption resistors R2, R4, and R7, respectively. The sources of the N-type MOS tubes Q1, Q2, and Q3 are grounded, and the drains of the N-type MOS tubes Q1 and Q2 are connected to two pins of the primary side of the center-tapped transformer TR1, respectively; one pin of the secondary side of the center-tapped transformer TR1 is connected in series to a matching inductor L1 and a piezoelectric transducer Y1 and then grounded, and the other pin of the secondary side is grounded. The drain of the N-type MOS tube Q3 is connected in series to a diode D1 and a tail wave absorption resistor R5 and then connected in parallel to the piezoelectric transducer Y1, and the piezoelectric transducer Y1 is also connected in parallel to a detection circuit.

[0010] Further, in the detection circuit, the voltage dividing resistors R8, R10, and R9 are connected in series and then connected in parallel to the piezoelectric transducer Y1. One end of an alternating current coupling capacitor C1 is connected between the voltage dividing resistors R9 and R10, and the other end is connected to the positive input end of an operational amplifier U4; one end of a bias resistor R14 is connected to the positive input end of the operational amplifier U4, and the other end is connected to a bias voltage; one end of a bias resistor R11 is connected to the positive input end of the operational amplifier U4, and the other end is grounded. One end of a bypass capacitor C2 is grounded, the other end is connected in series to a matching resistor R13 and then connected to the negative input end of the operational amplifier U4; one end of a feedback resistor R12 is connected to the negative input end of the operational amplifier U4, and the other end is connected to the output end of the operational amplifier U4; and the output end of the operational amplifier U4 is connected to an ADC to complete voltage sampling.

[0011] Preferably, the ratio of R9 to R8+R9+R10 is 1:100-500.

[0012] Preferably, the ratio of R13 to R12 is greater than 20, and the ratio of R13 to is greater than 20, wherein, is the center frequency of the piezoelectric transducer Y1.

[0013] Preferably, the PWM1 excitation signal, the PWM2 excitation signal, and the PWM3 excitation signal are all square waves with adjustable pulse width and duty cycle.

[0014] Preferably, the PWM1 excitation signal and the PWM2 excitation signal are complementary PWM waves with a phase difference of 180°; after the emission of the PWM1 excitation signal and the PWM2 excitation signal ends, the PWM3 excitation signal is turned on synchronously to perform tail wave absorption.

[0015] Further, when the PWM3 excitation signal is turned on to perform tail wave absorption, ADC sampling is performed synchronously for five pulse periods; if the effective value is greater than 10% of the waveform voltage across the piezoelectric transducer Y1, a fault is absorbed; if the effective value is less than or equal to 10%, normal absorption is performed.

[0016] Further, the parasitic diode of the diode D1 and the N-type MOS tube Q3 forms a bidirectional blocking circuit to avoid the conduction of the parasitic diode in the negative half cycle when the N-type MOS tube Q3 is not conducting.

[0017] Optionally, the MOS tube drivers U1, U2, and U3 all use the MOS tube driving chip UCC27624DR, which is powered by 12V.

[0018] Optionally, the PWM1 excitation signal, the PWM2 excitation signal, and the PWM3 excitation signal are generated by FPGA, CPLD, a single-chip microcomputer, DSP, ARM, or SOC.

[0019] Compared with the prior art, the present application has the following beneficial effects: 1. The prior art has low absorption working voltage and small absorption current, and cannot cope with the scene of high-voltage and large-current power ultrasound. The present application has high working voltage and large absorption energy, and can absorb the tail wave of high-voltage and large-current power ultrasound driving circuit.

[0020] 2. The prior art uses asynchronous absorption, which leads to absorption energy leakage due to absorption delay. The present application uses a synchronous absorption method, which opens the absorption circuit at the same time as the ultrasonic driving circuit is turned off, avoiding absorption delay and absorption energy leakage.

[0021] 3. The prior art lacks absorption effect detection, and cannot form a closed-loop feedback, so it cannot intervene in the case of absorption circuit failure or performance degradation. The present application introduces a closed-loop feedback mechanism to feedback the absorption effect in real time and intervene in a timely manner in the case of absorption circuit failure or performance degradation. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A power ultrasonic synchronization tail wave absorption detection circuit structure schematic diagram for an embodiment of the present application.

[0023] Figure 2 An ultrasonic drive and tail wave absorption circuit control logic timing diagram in an embodiment of the present application.

[0024] Figure 3 A waveform generation and tail wave absorption effect detection control logic diagram in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0026] It should be noted that the features in the following embodiments and implementation manners can be combined with each other without conflict.

[0027] The present application will be further described in detail below with reference to the drawings and embodiments. It should be noted that the following described embodiments are intended to facilitate the understanding of the present application, and do not limit the present application in any way.

[0028] As Figure 1As shown, a kind of power ultrasonic synchronous tail wave absorption detection circuit, U1 is MOS tube driving chip UCC27624DR, the chip 12V power supply, input pin is connected PWM1 excitation signal, output pin is connected in series with damping matching resistance R1, to the gate of N-type MOS tube Q1, while in the gate parallel peak absorption resistance R2;The source electrode of Q1 is grounded, drain electrode is connected to the primary side of center-tapped transformer TR1, TR1 center tap is connected to VDD_100V DC power supply, the other pin of the primary side of center-tapped transformer TR1 is connected to the drain electrode of N-type MOS tube Q2, the source electrode of Q2 is grounded, and the gate of Q2 is connected in parallel with peak absorption resistance R4, and is connected in series with damping absorption resistance R3, R3 is connected in series into the output end of MOS driver U2, U2 is also UCC27624DR, the supply voltage is 12V, and the input pin of U2 is connected with excitation signal PWM2.The one end of the secondary side of TR1 is connected with matching inductor L1, and the other end is grounded.Matching inductor L1 is connected in series into the loop where piezoelectric transducer Y1 is located, diode D1, absorption resistance R5 and N-type MOS tube Q3 are connected in series to form absorption circuit and are connected in parallel with piezoelectric transducer Y1, the anode of diode D1 is connected in parallel with the anode of piezoelectric transducer Y1, and the cathode is connected in series with absorption resistance R5, and the other end of R5 is connected in series into the drain electrode of N-type MOS tube Q3, the source electrode of Q3 is grounded, and the gate is connected in parallel with peak absorption resistance R7 and damping matching resistance R6, and the other end of R6 is connected in series into the output end of MOS tube driving device U3, and the input end of MOS tube driving device U3 is connected with signal PWM3.Divided voltage R8, R10, R9 are connected in series and are connected in parallel with piezoelectric transducer Y1, one end of AC coupling capacitor C1 is connected to the middle of R10 and R9, and the other end is connected to the positive input end of operational amplifier U4, R14 and R11 are bias resistors, one end of bias resistor R14 is connected to the positive input end of operational amplifier U4, and the other end is connected to VCC_5V bias voltage, one end of bias resistor R11 is grounded, and the other end is connected to the positive input end of operational amplifier U4.Matching resistance R13 and bypass capacitor C2 are connected in series and are connected to the reverse input end of operational amplifier U4, R12 is feedback resistance, one end is connected to the reverse input end of operational amplifier U4, and one end is connected to the output end of operational amplifier U4, and the output end of operational amplifier U4 is connected to ADC to complete voltage sampling.

[0029] In the embodiment of the application, PWM1, PWM2 and PWM3 are square waves with adjustable pulse width and duty ratio, PWM1 and PWM2 are used as complementary square waves for the upper and lower tubes of the push-pull circuit, the pulse width of PWM1 and PWM2 is 1900ns, each set of complementary waveforms has 5, the dead time is 100ns, and the complementary output of 250KHz is realized. Figure 2 As shown in the timing diagram of PWM1, PWM2 and PWM3.

[0030] The PWM wave adopted in the application is generated by an FPGA, and alternatively, the PWM wave can be generated by a CPLD, a single-chip microcomputer, a DSP, an ARM, or an SOC.

[0031] U1, U2, and U3 are MOS tube drivers, and the model number thereof is UCC27624.

[0032] R1, R3, and R6 are damping absorption resistors, which prevent self-oscillation of the MOS tube, and the resistance value thereof is 10R.

[0033] Q1, Q2, and Q3 are N-type MOS tubes, wherein Q1 and Q2 and TR1 (a center-tapped transformer) constitute a main topology of a push-pull driving circuit, and the turns ratio of the primary side and the secondary side of the transformer is 1:4; Q3, D1, and R5 constitute core components of a tail wave absorption circuit, and the working principle thereof is as follows: Q3 is an N-type MOS, and a parasitic diode exists, that is, there is a half-wave conduction problem of the MOS tube under the condition that Q3 is not turned on, and therefore a diode D1 opposite to the parasitic diode is connected in series in the loop to prevent the parasitic diode of the MOS tube from passing through the half-wave of alternating current under the condition that the MOS tube is not turned on. R5 is an absorption resistor, and the resistance value thereof is selected as 5 ohms; the absorption resistor needs to have the characteristics of small resistance value and large power.

[0034] Y1 is a piezoelectric transducer, the piezoelectric material of which is PZT4, the center frequency of the piezoelectric transducer is 250 KHz, the working frequency band is 177-344 KHz, the acoustic matching material is epoxy resin, and L1 is a matching inductor.

[0035] L1 is a matching inductor of the piezoelectric transducer Y1, and an L-type matching is adopted, because the piezoelectric transducer works in a series resonance state and is capacitive, according to the Van-Dyke equivalent circuit model, the piezoelectric transducer in the series resonance state is equivalent to a parallel connection of a resistor and a capacitor. The significance of the L-type impedance is to match the imaginary part to 0 and the real part to the target impedance, which is generally 50 ohms, and the target impedance is also matched to 50 ohms here. Further, if the equivalent parallel resistance of the piezoelectric transducer is too small, which is usually lower than the target impedance, a parallel capacitor needs to be connected to achieve the target impedance matching.

[0036] D1, R5, Q3 are core circuits for realizing tail wave absorption, D1 is a diode, which is used to form a bidirectional cut-off circuit with the parasitic diode of Q3 MOS tube, so as to avoid the conduction of the parasitic diode in the negative half cycle when the MOS tube is not conducting. R5 is a tail wave absorption resistor, which is generally selected to be a high-power and low-resistance resistor. Q3 is a synchronous MOS tube, which is used to ensure that the tail wave is opened synchronously when Q1 and Q2 are emitted, so as to avoid the tail wave leakage caused by asynchronous opening. The absorption circuit of the application is a one-way absorption circuit, and further, it can be designed into a two-way absorption circuit.

[0037] R8, R10, and R9 constitute a voltage division circuit. Since the peak-to-peak value of the piezoelectric transducer is about 1300V under a driving voltage of 100V, the voltage division coefficient is 1 / 300, that is, the ratio of R9 to R8+R9+R10 is 1:300, and the peak-to-peak value of R9 is about 4V. In order to avoid the top of the operational amplifier being eliminated when it exceeds the swing, a certain margin is reserved.

[0038] In the detection of the tail wave, the voltage can be detected, or the current can be detected. Here, the voltage is selected. Optionally, the current can be measured by being connected to a high-precision small resistor or by a current transformer.

[0039] C1, R14, R11, U4, R13, C2, and R12 constitute a voltage follower circuit with DC bias and AC coupling. C1 is an AC coupling capacitor, R14 and R11 constitute a DC bias resistor, and the DC bias voltage under a 5V voltage is 2.5V. U4 is an operational amplifier, which can be powered by a single power supply because the DC bias is added. C2, R12, and R13 constitute an AC feedback. The overall circuit is a voltage follower with DC bias and capacitor coupling. Because the sampling circuit adds DC bias, it can be powered by a single power supply. Optionally, it can be powered by a double power supply without DC bias.

[0040] After being sampled by the sampling resistor R9, the voltage is input to the ADC through the voltage follower. The ADC here is LTC1405, and the sampling rate is 5MHz. After the absorption switch tube Q3 is opened, the ADC sampling is performed for five pulse periods, that is, 20us. If the effective value is greater than 10% of the normal emission waveform voltage, the absorption fault is reported. If it is less than or equal to 10%, the absorption is normal. The calculation formula of the tail wave effective value is as follows: In the formula, is the voltage effective value, is the number of sampling points, represents the first The formula can calculate the amplitude of the voltage of a sampling point. The formula can calculate the effective value of DC, AC and AC voltage containing harmonic components. When using hardware programming language, using division and square root will occupy a large number of logic resources, and multiplication and addition are directly used for calculation.

[0041] As shown in Figure 3 The control logic of waveform generation and tail wave absorption effect detection is as follows: The initialization parameters include setting the number of transmitted pulses, duty cycle, pulse repetition rate, pulse width, dead time and absorption time.

[0042] Complementary PWM waves, PWM1 and PWM2, are transmitted as excitation signals of the push-pull circuit, PWM1 and PWM2 have a phase difference of 180°, the dead time is set to 100ns, the pulse width is 1900ns, and the number of pulses in a group is 5. Optionally, the pulse width, dead time and number of pulses can be adjusted according to actual needs.

[0043] After the transmission of PWM2 ends, that is, the pulse transmission is completed, the tail wave absorption stage is entered, and PWM3 is opened synchronously at this time to perform absorption, and the opening time is 500us, which can be adjusted according to actual needs.

[0044] The effective value after absorption is measured synchronously during tail wave absorption, which is to simplify the measurement. Since the tail wave is an AC signal, measuring the effective value can evaluate the energy size, and only less than or equal to 10% of the ultrasonic driving waveform is considered to be completely absorbed, which meets the expectation. If the waveform after absorption is greater than 10% of the driving waveform, the absorption circuit is considered to be invalid.

[0045] The circuit of the present application has the characteristics of simple topology and reliable performance, and the use of discrete components can withstand high voltage and large current impact, which is particularly suitable for tail wave absorption of power ultrasound.

[0046] Further, the present application proposes a synchronous control logic of an ultrasonic transmitting circuit and a tail wave absorption circuit, which avoids the risk of tail wave leakage caused by absorption delay.

[0047] Further, the present application proposes a tail wave detection effect feedback mechanism, that is, using ADC to sample the tail wave to evaluate the absorption effect.

[0048] Further, the present application proposes a method for calculating the effective value of voltage using hardware description language, which avoids using division and saves valuable logic resources.

[0049] The above-described embodiments have described the technical solutions and beneficial effects of the present application in detail, and it should be understood that the above-described is only a specific embodiment of the present application and is not used to limit the present application, and any modification, supplement and equivalent replacement made within the principle range of the present application should be included in the protection range of the present application.

Claims

1. A power ultrasonic synchronous wake wave absorption detection circuit, characterized in that, This includes a center-tapped transformer TR1, MOSFET drivers U1, U2, and U3, and N-type MOSFETs Q1, Q2, and Q3; The input pins of MOSFET drivers U1, U2, and U3 are connected to the PWM1, PWM2, and PWM3 excitation signals, respectively. The output pins of MOSFET drivers U1, U2, and U3 are connected in series with damping matching resistors R1, R3, and R6 to the gates of N-type MOSFETs Q1, Q2, and Q3, respectively. Meanwhile, peak absorption resistors R2, R4, and R7 are connected in parallel to the gates of N-type MOSFETs Q1, Q2, and Q3, respectively. The sources of N-type MOSFETs Q1, Q2, and Q3 are grounded, and the drains of N-type MOSFETs Q1 and Q2 are connected to two pins of the primary side of the center-tapped transformer TR1, respectively. One pin of the secondary side of the center-tapped transformer TR1 is connected in series with the matching inductor L1 and the piezoelectric transducer Y1 and then grounded, and the other pin of the secondary side is grounded. Diode D1, tail wave absorption resistor R5, and the drain of N-type MOSFET Q3 are connected in series and then in parallel with piezoelectric transducer Y1. A detection circuit is also connected in parallel across the two ends of piezoelectric transducer Y1.

2. The power ultrasonic synchronous wake wave absorption detection circuit according to claim 1, characterized in that, In the detection circuit, the voltage divider resistors R8, R10, and R9 are connected in series and then in parallel with the piezoelectric transducer Y1; One end of the AC coupling capacitor C1 is connected between the voltage divider resistors R9 and R10, and the other end is connected to the positive input terminal of the operational amplifier U4; one end of the bias resistor R14 is connected to the positive input terminal of the operational amplifier U4, and the other end is connected to the bias voltage; one end of the bias resistor R11 is connected to the positive input terminal of the operational amplifier U4, and the other end is grounded. One end of the bypass capacitor C2 is grounded, and the other end is connected in series with the matching resistor R13 and then connected to the inverting input of the operational amplifier U4; one end of the feedback resistor R12 is connected to the inverting input of the operational amplifier U4, and the other end is connected to the output of the operational amplifier U4; the output of the operational amplifier U4 is connected to the ADC to complete voltage sampling.

3. The power ultrasonic synchronous wake wave absorption detection circuit according to claim 2, characterized in that, The ratio of R9 to R8 + R9 + R10 is 1:100~500.

4. The power ultrasonic synchronous wake wave absorption detection circuit according to claim 2, characterized in that, The ratio of R13 to R12 is greater than 20, and R13 and The ratio is greater than 20, where, The center frequency of the piezoelectric transducer Y1 is given.

5. The power ultrasonic synchronous wake wave absorption detection circuit according to claim 1, characterized in that, The PWM1, PWM2, and PWM3 excitation signals are all square waves with adjustable pulse width and duty cycle.

6. The power ultrasonic synchronous wake wave absorption detection circuit according to claim 1, characterized in that, The PWM1 and PWM2 excitation signals are complementary PWM waves with a phase difference of 180°. After the PWM1 and PWM2 excitation signals are emitted, the PWM3 excitation signal is activated synchronously to absorb the wake wave.

7. The power ultrasonic synchronous wake wave absorption detection circuit according to claim 6, characterized in that, When the PWM3 excitation signal is turned on for tailwave absorption, ADC sampling is performed simultaneously for five pulse cycles. If the effective value is greater than 10% of the waveform voltage across the piezoelectric transducer Y1, the absorption is faulty; if it is less than or equal to 10%, the absorption is normal.

8. The power ultrasonic synchronous wake wave absorption detection circuit according to claim 1, characterized in that, Diode D1 and the parasitic diode of N-type MOSFET Q3 form a bidirectional cutoff circuit to prevent the parasitic diode from conducting during the negative half-cycle when N-type MOSFET Q3 is not conducting.

9. The power ultrasonic synchronous wake wave absorption detection circuit according to claim 1, characterized in that, The MOSFET drivers U1, U2, and U3 all use the MOSFET driver chip UCC27624DR, which is powered by 12V.

10. The power ultrasonic synchronous wake wave absorption detection circuit according to claim 1, characterized in that, The PWM1 excitation signal, PWM2 excitation signal, and PWM3 excitation signal are generated by FPGA, CPLD, microcontroller, DSP, ARM, or SOC.

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