An Adaptive Sampling Open-Circuit Voltage MPPT Method and System for Piezoelectric Energy Acquisition

Abstract

This invention discloses an adaptive open-circuit voltage sampling (MPPT) method and system for piezoelectric energy harvesting. The method is applied to an MPPT control circuit, which includes a duty cycle monitoring circuit, a sampling signal generation circuit, and a sample-and-hold circuit. The method includes: using the duty cycle monitoring circuit to monitor the duty cycle of the comparison signal generated by the rectifier in real time and generating a monitoring signal; using the sampling signal generation circuit to generate a sampling signal based on the monitoring signal; and using the sample-and-hold circuit to sample the open-circuit voltage of the piezoelectric power supply to determine the maximum power point voltage, controlling the MPPT power stage in the piezoelectric energy harvesting circuit to perform maximum power point tracking (MPPT) based on the MPPT voltage. This invention optimizes the MPPT control circuit. When the system has high tracking accuracy, open-circuit voltage sampling and MPPT are unnecessary, thereby reducing energy waste caused by open-circuit sampling and power consumption of the MPPT circuit, and improving energy harvesting efficiency.

Description

Technical Field

[0001] This invention belongs to the field of maximum power point tracking technology, specifically relating to an adaptive sampling open-circuit voltage (MPPT) method and system for piezoelectric energy acquisition. Background Technology

[0002] Piezoelectric energy harvesting technology features high power density, small size, and relatively simple structure, making it ideal for powering portable electronic devices. To ensure the piezoelectric energy harvesting device consistently outputs maximum power, it needs to employ MPPT (Maximum Power Point Tracking) technology. The efficiency of the MPPT circuit is related to the duty cycle of the comparison signal generated by the rectifier in the piezoelectric energy harvesting circuit. When the duty cycle is 50%, the theoretical tracking efficiency of the MPPT circuit is 100%. The greater the deviation of the duty cycle from 50%, the lower the tracking efficiency of the MPPT circuit. In such cases, it is necessary to re-sample the open-circuit voltage and perform MPPT tracking.

[0003] The traditional FOCV MPPT method performs MPPT periodically (e.g., 128 piezoelectric vibration cycles), activating the process even in steady-state conditions where MPPT is not required. Unnecessary open-circuit sampling leads to interruptions in energy harvesting and causes excessive energy loss in the MPPT circuit, resulting in reduced energy harvesting efficiency. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides an adaptive open-circuit voltage sampling (MPPT) method and system suitable for piezoelectric energy acquisition. The technical problem to be solved by this invention is achieved through the following technical solution:

[0005] In a first aspect, the present invention provides an adaptive sampling open-circuit voltage MPPT method suitable for piezoelectric energy acquisition, the method comprising:

[0006] The duty cycle monitoring circuit in the MPPT control circuit is used to monitor the comparison signal V generated by the rectifier in the piezoelectric energy harvesting circuit in each monitoring cycle in real time. COMP Generates a characterization comparison signal V COMP The duty cycle monitoring signal; the monitoring signal includes: a first monitoring signal V DET Second monitoring signal V DET The first monitoring signal V DET Comparison signal V COMP The conduction pulse width corresponds to the second monitoring signal V. DET Comparison signal V COMP The width of the turn-off pulse corresponds to;

[0007] Using the sampling signal generation circuit in the MPPT control circuit, the first monitoring signal V is compared. DET Second monitoring signal V DET Select the first monitoring signal V DET Second monitoring signal V DET The larger value in is used as the first output signal V DET_Max Select the first monitoring signal V DET Second monitoring signal V DET The smaller value in is used as the second output signal V DET_Min According to the first output signal V DET_Max Second output signal V DET_Min Output comparison signal V MPP_COMP For the comparison signal V MPP_COMP When a comparison signal V is detected, a judgment is made. MPP_COMP A low-level pulse is generated at the falling edge of the signal as the sampling signal V. SAMPLE ;

[0008] If a sampling signal V is generated SAMPLE Using the sample-and-hold circuit in the MPPT control circuit, the open-circuit voltage V of the piezoelectric power supply in the piezoelectric energy acquisition circuit is measured. P Sampling is performed to determine the maximum power point voltage V. MPPT The MPPT power stage in the piezoelectric energy harvesting circuit is controlled according to the maximum power point voltage V. MPPT Work is performed to achieve maximum power point tracking.

[0009] In one embodiment of the present invention, the duty cycle monitoring circuit includes:

[0010] The monitoring and control signal generation circuit and the capacitor charging and discharging circuit are connected in sequence.

[0011] In one embodiment of the present invention, the duty cycle monitoring circuit in the MPPT control circuit is used to monitor in real time the comparison signal V generated by the rectifier in the piezoelectric energy acquisition circuit during each monitoring cycle. COMP Generates a characterization comparison signal V COMP The duty cycle monitoring signal includes:

[0012] The monitoring and control signal generation circuit generates the signal in the enable signal E. N_MPPT Under the control of [the system], based on the comparison signal V generated by the rectifier in the piezoelectric energy acquisition circuit within a monitoring cycle, [the system]... COMP This generates monitoring and control signals;

[0013] The capacitor charging and discharging circuit generates a comparison signal V based on the monitoring and control signal. COMPThe first monitoring signal V for duty cycle status DET Second monitoring signal V DET .

[0014] In one embodiment of the present invention, the first monitoring signal V DET The comparison signal V generated by the rectifier COMP It is proportional to the width of the conduction pulse.

[0015] In one embodiment of the present invention, the second monitoring signal V DET The comparison signal V generated by the rectifier COMP It is proportional to the width of the turn-off pulse.

[0016] In one embodiment of the present invention, the sampling signal generation circuit includes:

[0017] The voltage selection circuit, voltage divider circuit, comparator circuit, and low pulse generation circuit are connected in sequence.

[0018] In one embodiment of the present invention, the sampling signal generation circuit in the MPPT control circuit is used to compare the first monitoring signal V. DET Second monitoring signal V DET Select the first monitoring signal V DET Second monitoring signal V DET The larger value in is used as the first output signal V DET_Max Select the first monitoring signal V DET Second monitoring signal V DET The smaller value in is used as the second output signal V DET_Min According to the first output signal V DET_Max Second output signal V DET_Min Output comparison signal V MPP_COMP For the comparison signal V MPP_COMP When a comparison signal V is detected, a judgment is made. MPP_COMP A low-level pulse is generated at the falling edge of the signal as the sampling signal V. SAMPLE ,include:

[0019] The voltage selection circuit selects the first monitoring signal V. DET Second monitoring signal V DET To perform the detection, select the first monitoring signal V. DET Second monitoring signal V DET The larger value in is used as the first output signal V DET_Max And output to the voltage divider circuit to select the first monitoring signal V DET Second monitoring signal V DET The smaller value in is used as the second output signal V DET_Min And output to the comparison circuit;

[0020] The voltage divider circuit outputs the first signal V. DET_Max The voltage is divided to produce a voltage V. Div_Max ;

[0021] The comparator circuit outputs the second signal V. DET_Min and voltage divider V Div_Max Compare and output comparison signal V MPP_COMP ;

[0022] The low-pulse generation circuit compares the signal V. MPP_COMP When a comparison signal V is detected, a judgment is made. MPP_COMP A low-level pulse is generated at the falling edge of the signal as the sampling signal V. SAMPLE .

[0023] Secondly, the present invention provides an adaptive sampling open-circuit voltage MPPT system suitable for piezoelectric energy acquisition, the system comprising:

[0024] Duty cycle monitoring circuit, sampling signal generation circuit, and sample-and-hold circuit; among which,

[0025] The duty cycle monitoring circuit is used to monitor in real time the comparison signal V generated by the rectifier in the piezoelectric energy acquisition circuit during each monitoring cycle. COMP Generates a characterization comparison signal V COMP The duty cycle monitoring signal; the monitoring signal includes: a first monitoring signal V DET Second monitoring signal V DET The first monitoring signal V DET Comparison signal V COMP The conduction pulse width corresponds to the second monitoring signal V. DET For comparison signal V COMP The width of the turn-off pulse corresponds to;

[0026] The sampling signal generation circuit is used to compare the first monitoring signal V. DET Second monitoring signal V DET Select the first monitoring signal V DET Second monitoring signal V DET The larger value in is used as the first output signal V DET_Max Select the first monitoring signal V DET Second monitoring signal V DET The smaller value in is used as the second output signal V DET_Min According to the first output signal V DET_Max Second output signal V DET_Min Output comparison signal V MPP_COMP For the comparison signal V MPP_COMPWhen a comparison signal V is detected, a judgment is made. MPP_COMP A low-level pulse is generated at the falling edge of the signal as the sampling signal V. SAMPLE ;

[0027] The sample-and-hold circuit is used to, if a sampled signal V is generated SAMPLE The open-circuit voltage V of the piezoelectric power supply in the piezoelectric energy harvesting circuit. P Sampling is performed to determine the maximum power point voltage V. MPPT The MPPT power stage in the piezoelectric energy harvesting circuit is controlled according to the maximum power point voltage V. MPPT Work is performed to achieve maximum power point tracking.

[0028] In one embodiment of the present invention, the duty cycle monitoring circuit includes:

[0029] The monitoring and control signal generation circuit and the capacitor charging and discharging circuit are connected in sequence; among them,

[0030] The monitoring and control signal generation circuit includes: a frequency divider and a frequency division control circuit; wherein...

[0031] The input terminal of the frequency divider is connected to the first input terminal of the frequency division control circuit, and is connected to the comparison signal V generated by the rectifier. COMP The output terminal is connected to the second input terminal of the frequency division control circuit;

[0032] The third input terminal of the frequency division control circuit is connected to the enable signal E. N_MPPT ;

[0033] The capacitor charging and discharging circuit includes: a first current source I, a second current source I, a first PMOS transistor Q, a second PMOS transistor Q, a first NMOS transistor Q, a second NMOS transistor Q, a first charging capacitor C, and a second charging capacitor C; wherein,

[0034] The input terminal of the first current source I is connected to the power supply voltage, and the output terminal is connected to the source of the first PMOS transistor Q.

[0035] The input terminal of the second current source I is connected to the power supply voltage, and the output terminal is connected to the source of the second PMOS transistor Q.

[0036] The gate of the first PMOS transistor Q is connected to the first output terminal of the frequency division control circuit, and the drain is connected to the first terminal of the first charging capacitor C.

[0037] The gate of the second PMOS transistor Q is connected to the second output terminal of the frequency division control circuit, and the drain is connected to the first terminal of the second charging capacitor C.

[0038] The source of the first NMOS transistor Q is grounded, its gate is connected to the third output terminal of the frequency division control circuit, and its drain is connected to the drain of the first PMOS transistor Q.

[0039] The source of the second NMOS transistor Q is grounded, its gate is connected to the third output terminal of the frequency division control circuit, and its drain is connected to the drain of the second PMOS transistor Q.

[0040] The second terminal of the first charging capacitor C is connected to the source of the first NMOS transistor Q; the voltage across the first charging capacitor C serves as the first monitoring signal V. DET ;

[0041] The second terminal of the second charging capacitor C is connected to the source of the second NMOS transistor Q; the voltage across the second charging capacitor C serves as the second monitoring signal V. DET .

[0042] In one embodiment of the present invention, the sampling signal generation circuit includes:

[0043] The circuit includes a voltage selection circuit, a voltage divider circuit, a comparator circuit, and a low-pulse generation circuit; among which,

[0044] The first input terminal of the voltage selection circuit is connected to the first monitoring signal V. DET The second input terminal is connected to the second monitoring signal V. DET The first output terminal is connected to the input terminal of the voltage divider circuit, and the second output terminal is connected to the inverting input terminal of the comparator circuit.

[0045] The output terminal of the voltage divider circuit is connected to the non-inverting input terminal of the comparator circuit;

[0046] The output terminal of the comparator circuit is connected to the input terminal of the low pulse generation circuit.

[0047] The output terminal of the low pulse generation circuit serves as the output terminal of the sampling signal generation circuit.

[0048] The beneficial effects of this invention are:

[0049] The solution provided by this invention utilizes a duty cycle monitoring circuit to monitor the duty cycle of the comparison signal generated by the rectifier in real time. Combined with a sampling signal generation circuit, the monitored signal is analyzed to determine whether to generate a sampling signal, thereby adjusting the MPPT control circuit and improving the efficiency of the piezoelectric energy harvesting circuit. When the duty cycle is 50%, the theoretical tracking efficiency of the MPPT circuit is 100%. The greater the deviation of the duty cycle from 50%, the lower the tracking efficiency of the MPPT circuit. In this case, the holding circuit re-samples the open-circuit voltage of the piezoelectric power supply to determine the maximum power point voltage and performs maximum power point tracking. Through this method, the open-circuit sampling and MPPT control circuits can be adjusted as needed based on the duty cycle signal generated by the rectifier, achieving adaptive control of open-circuit sampling and MPPT. When the duty cycle approaches 50%, the relevant circuit for open-circuit voltage sampling is shut down, saving losses in the piezoelectric energy harvesting device, reducing energy waste, and improving energy collection efficiency. Attached Figure Description

[0050] Figure 1 This is a flowchart illustrating an adaptive sampling open-circuit voltage (MPPT) method for piezoelectric energy acquisition provided in an embodiment of the present invention.

[0051] Figure 2 This is a schematic diagram of the MPPT control circuit provided in an embodiment of the present invention;

[0052] Figure 3 This is a circuit diagram of a duty cycle monitoring circuit provided in an embodiment of the present invention;

[0053] Figure 4 This is a circuit diagram of a monitoring and control signal generation circuit provided in an embodiment of the present invention;

[0054] Figure 5 This is a circuit diagram of a capacitor charging and discharging circuit provided in an embodiment of the present invention;

[0055] Figure 6 This is a schematic diagram of a sampling signal generation circuit provided in an embodiment of the present invention;

[0056] Figure 7 This is a schematic diagram showing the connection between the MPPT control circuit and the piezoelectric energy acquisition circuit provided in an embodiment of the present invention;

[0057] Figure 8 This is a schematic diagram of relevant waveforms for the adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition provided in this embodiment of the invention;

[0058] Figure 9 This is a simulation waveform diagram of the adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition provided in an embodiment of the present invention.

[0059] Figure Labels

[0060] 10-Duty cycle monitoring circuit, 101-Monitoring control signal generation circuit, 102-Capacitor charging and discharging circuit, 20-Sampling signal generation circuit, 201-Voltage selection circuit, 202-Voltage divider circuit, 203-Comparison circuit, 204-Low pulse generation circuit, 30-Sample and hold circuit. Detailed Implementation

[0061] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0062] This invention provides an adaptive sampling open-circuit voltage MPPT method and system suitable for piezoelectric energy acquisition.

[0063] Below, we will first introduce an adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition provided by an embodiment of the present invention.

[0064] Firstly, such as Figure 1 As shown in the figure, the adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition provided by this embodiment of the invention is applied to an MPPT control circuit. A schematic diagram of the MPPT control circuit can be found in the figure. Figure 2 The MPPT control circuit may include: a duty cycle monitoring circuit 10, a sampling signal generation circuit 20, and a sample-and-hold circuit 30 connected in sequence; the adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition may include the following steps:

[0065] S1, using the duty cycle monitoring circuit 10 in the MPPT control circuit, the comparison signal V generated by the rectifier in the piezoelectric energy acquisition circuit in each monitoring cycle is monitored in real time. COMP Generates a characterization comparison signal V COMP The duty cycle monitoring signal; the monitoring signal includes: the first monitoring signal V DET1 Second monitoring signal V DET2 The first monitoring signal V DET1 Comparison signal V COMP The conduction pulse width corresponds to the second monitoring signal V. DET2 Comparison signal V COMP The corresponding turn-off pulse width.

[0066] Specifically, S1 can include:

[0067] S11, the monitoring and control signal generation circuit 101 is in the enable signal E N_MPPT Under the control of the circuit, the comparison signal V generated by the rectifier in the piezoelectric energy acquisition circuit within a monitoring cycle is used.COMP This generates monitoring and control signals;

[0068] S12, the capacitor charging and discharging circuit 102 generates a comparison signal V based on the monitoring and control signal. COMP The first monitoring signal V for duty cycle status DET1 Second monitoring signal V DET2 .

[0069] Specifically, the duty cycle monitoring circuit 10, such as Figure 3 As shown, it may include:

[0070] The monitoring and control signal generation circuit 101 and the capacitor charging and discharging circuit 102 are connected in sequence.

[0071] Monitoring and control signal generation circuit 101, such as Figure 4 As shown, it may include: a frequency divider and a frequency division control circuit; wherein,

[0072] The input terminal of the frequency divider is connected to the first input terminal of the frequency division control circuit, and is connected to the comparison signal V generated by the rectifier. COMP The output terminal is connected to the second input terminal of the frequency divider control circuit;

[0073] The third input terminal of the frequency division control circuit is connected to the enable signal E. N_MPPT .

[0074] Optionally, the frequency divider compares the comparison signal V generated by the rectifier in each monitoring cycle. COMP Monitoring is performed, and a DIV signal is generated every 128 piezoelectric vibration cycles to trigger the frequency division control circuit. The frequency division control circuit uses the comparison signal V generated by the rectifier... COMP The DIV signal generates control signals V1, V2, and V. N And enabled by signal E N_MPPT Enable control. Specifically, V1 is controlled by V COMP Inverting V gives V2, which is V. COMP V N It remains at a low level, generating a high-level pulse signal every 128 piezoelectric vibration cycles, thus changing the voltage V. DET1 and V DET2 Lower it to prepare for the next monitoring cycle.

[0075] Capacitor charging and discharging circuit 102, such as Figure 5 As shown, it may include: a first current source I1, a second current source I2, a first PMOS transistor Q1, a second PMOS transistor Q2, a first NMOS transistor Q3, a second NMOS transistor Q4, a first charging capacitor C1, and a second charging capacitor C2; wherein,

[0076] The input terminal of the first current source I1 is connected to the power supply voltage, and the output terminal is connected to the source of the first PMOS transistor Q1.

[0077] The input terminal of the second current source I2 is connected to the power supply voltage, and the output terminal is connected to the source of the second PMOS transistor Q2.

[0078] The gate of the first PMOS transistor Q1 is connected to the first output terminal of the frequency divider control circuit, and the drain is connected to the first terminal of the first charging capacitor C1.

[0079] The gate of the second PMOS transistor Q2 is connected to the second output terminal of the frequency divider control circuit, and the drain is connected to the first terminal of the second charging capacitor C2.

[0080] The source of the first NMOS transistor Q3 is grounded, its gate is connected to the third output terminal of the frequency divider control circuit, and its drain is connected to the drain of the first PMOS transistor Q1.

[0081] The source of the second NMOS transistor Q4 is grounded, its gate is connected to the third output terminal of the frequency divider control circuit, and its drain is connected to the drain of the second PMOS transistor Q2.

[0082] The second terminal of the first charging capacitor C1 is connected to the source of the first NMOS transistor Q3; the voltage across the first charging capacitor C1 serves as the first monitoring signal V. DET1 ;

[0083] The second terminal of the second charging capacitor C2 is connected to the source of the second NMOS transistor Q4; the voltage across the second charging capacitor C2 serves as the second monitoring signal V. DET2 .

[0084] Specifically, the first charging capacitor C1 and the first NMOS transistor Q3 are connected in parallel, and the second charging capacitor C2 and the second NMOS transistor Q4 are connected in parallel. The first PMOS transistor Q1 is connected to the comparison signal V generated by the rectifier. COMP When turned on, it opens and charges the first charging capacitor C1, in the comparison signal V generated by the rectifier. COMP Turn off when switched off; the second PMOS transistor Q2 is compared to the signal V generated by the rectifier. COMP When turned off, it turns on and charges the second charging capacitor C2, in the comparison signal V generated by the rectifier. COMP Turn on and off simultaneously. At the end of a cycle, the voltage across the first charging capacitor C1 serves as the first monitoring signal V. DET1 The voltage across the second charging capacitor C2 is sent to the sampling signal generation circuit 20 and serves as the second monitoring signal V. DET2 After being sent to the sampling signal generation circuit 20, V... N A high-level pulse occurs, turning on the first NMOS transistor Q3 and the second NMOS transistor Q4, releasing the charge on C1 and C2, and the voltage V...DET1 and V DET2 All jump to low level.

[0085] Understandably, the duty cycle monitoring circuit 10 compares the signal V generated by the rectifier. COMP The on and off pulse widths are monitored, and a monitoring signal is generated. The monitoring signal includes a first monitoring signal V. DET1 Second monitoring signal V DET2 The first monitoring signal V DET1 Second monitoring signal V DET2 respectively with V COMP The conduction pulse width and the turn-off pulse width correspond and are proportional. Optionally, the first monitoring signal V DET1 The monitoring signal corresponding to the comparison signal generated by the rectifier being turned on, the first monitoring signal V DET1 The comparison signal V generated by the rectifier COMP The signal is proportional to the conduction pulse width and is used to monitor the conduction pulse width. The second monitoring signal V... DET2 The monitoring signal V is the second monitoring signal that corresponds to the turn-off of the comparison signal generated by the rectifier. DET2 The comparison signal V generated by the rectifier COMP The voltage is proportional to the width of the turn-off pulse, and is used to monitor the turn-off pulse width. In this embodiment of the invention, the capacitor charging and discharging circuit 102 uses the voltages V1, V2, and V3 generated by the monitoring control signal generation circuit 101 to monitor the voltage. N The signal is activated to complete the comparison signal V generated by the rectifier. COMP Monitoring of duty cycle. Optionally, E N_MPPT The signal is an enable signal, when E N_MPPT When the signal is high, the duty cycle monitoring circuit starts working.

[0086] S2, using the sampling signal generation circuit 20 in the MPPT control circuit, compare the first monitoring signal V. DET1 Second monitoring signal V DET2 Select the first monitoring signal V DET1 Second monitoring signal V DET2 The larger value in is used as the first output signal V DET_Max Select the first monitoring signal V DET1 Second monitoring signal V DET2 The smaller value in is used as the second output signal V DET_Min According to the first output signal V DET_Max Second output signal V DET_Min Output comparison signal V MPP_COMP For the comparison signal V MPP_COMP When a comparison signal V is detected, a judgment is made. MPP_COMPA low-level pulse is generated at the falling edge of the signal as the sampling signal V. SAMPLE .

[0087] Specifically, the sampling signal generation circuit 20, such as Figure 6 As shown, it may include:

[0088] The voltage selection circuit 201, voltage divider circuit 202, comparator circuit 203, and low pulse generation circuit 204 are connected in sequence; among them...

[0089] The first input terminal of the voltage selection circuit 201 is connected to the first monitoring signal V. DET1 The second input terminal is connected to the second monitoring signal V. DET2 The first output terminal is connected to the input terminal of the voltage divider circuit 202, and the second output terminal is connected to the inverting input terminal of the comparator circuit 203.

[0090] The output of voltage divider circuit 202 is connected to the non-inverting input of comparator circuit 203;

[0091] The output of the comparator circuit 203 is connected to the input of the low pulse generation circuit 204;

[0092] The output of the low pulse generation circuit 204 is used as the output of the sampling signal generation circuit 20.

[0093] For S2, it can include:

[0094] S21, the voltage selection circuit 201 selects the first monitoring signal V. DET1 Second monitoring signal V DET2 To perform the detection, select the first monitoring signal V. DET1 Second monitoring signal V DET2 The larger value in is used as the first output signal V DET_Max The output is sent to the voltage divider circuit 202 to select the first monitoring signal V. DET1 Second monitoring signal V DET2 The smaller value in is used as the second output signal V DET_Min Output to comparator circuit 203;

[0095] S22, the voltage divider circuit 202 divides the first output signal V DET_Max The voltage is divided to produce a voltage V. Div_Max ;

[0096] S23, Comparison circuit 203 compares the second output signal V DET_Min and voltage divider V Div_Max Compare and output comparison signal V MPP_COMP ;

[0097] S24, Low pulse generation circuit 204 compares signal V MPP_COMPWhen a comparison signal V is detected, a judgment is made. MPP_COMP A low-level pulse is generated as the sampling signal V on the falling edge. SAMPLE .

[0098] Understandably, in this embodiment of the invention, the two input terminals of the voltage selection circuit 201 are connected to the two output terminals of the duty cycle monitoring circuit 10. The first output terminal of the voltage selection circuit 201 is connected to the input terminal of the voltage divider circuit 202, the output terminal of the voltage divider circuit 202 is connected to the inverting input terminal of the comparator circuit 203, the second output terminal of the voltage selection circuit 201 is connected to the non-inverting input terminal of the comparator circuit 203, and the output terminal of the comparator circuit 203 is connected to the input terminal of the low pulse generation circuit 204. Specifically, the first output terminal of the voltage selection circuit 201 will output the first monitoring signal V... DET1 Second monitoring signal V DET2 The larger value V in DET_Max The output is sent to the input terminal of the voltage divider circuit 202, and the second output terminal of the voltage selection circuit 201 outputs the first monitoring signal V. DET1 Second monitoring signal V DET2 The smaller value V in DET_Min The output is sent to the inverting input of the comparator circuit 203, and the voltage divider circuit 202 divides the larger voltage V. Div_Max The output is sent to the non-inverting input of the comparator circuit 203. The voltage divider circuit 202 may include a buffer, a first resistor, and a second resistor; wherein the positive input of the buffer serves as the input of the voltage divider circuit 202, the output of the buffer is connected to the negative input of the buffer, and the negative input of the buffer is connected to the first end of the first resistor; the second end of the first resistor is connected to the second end of the second resistor and serves as the output of the voltage divider circuit 202, and the second end of the second resistor is grounded. The comparator circuit 203 outputs V... DET_Min and V Div_Max Perform a numerical comparison, if V DET_Min Greater than V Div_Max Then compare the signal V MPP_COMP If V is high level, DET_Min Less than V Div_Max Then compare the signal V MPP_COMP The signal is low. The low-level pulse generation circuit 204 detects the comparison signal V. MPP_COMP A low-level pulse V is generated on the falling edge of the signal. SAMPLE The comparator circuit 203 can be constructed from a comparator.

[0099] This invention utilizes a duty cycle monitoring circuit 10 to monitor the duty cycle of the comparison signal generated by the rectifier. Combined with a sampling signal generation circuit 20, the monitored signal is analyzed to determine whether a sampling signal should be generated. This adjusts the MPPT control circuit, thereby improving the efficiency of the piezoelectric energy acquisition circuit. When the duty cycle is 50%, the theoretical tracking efficiency of the MPPT circuit is 100%. The greater the deviation of the duty cycle from 50%, the lower the tracking efficiency of the MPPT circuit. In this case, a sampling signal is generated, causing the sample-and-hold circuit 30 to resample the open-circuit voltage of the piezoelectric power supply to determine the maximum power point voltage and perform maximum power point tracking.

[0100] S3, if a sampling signal V is generated SAMPLE Using the sample-and-hold circuit 30 in the MPPT control circuit, the open-circuit voltage V of the piezoelectric power supply in the piezoelectric energy acquisition circuit is measured. P Sampling is performed to determine the maximum power point voltage V. MPPT The MPPT power stage in the piezoelectric energy harvesting circuit is controlled according to the maximum power point voltage V. MPPT Work is performed to achieve maximum power point tracking.

[0101] Specifically, when the sampled signal V SAMPLE When the signal is low, the sample-and-hold circuit 30 corresponds to the open-circuit voltage V of the power supply. P Sampling is performed to determine the maximum power point voltage signal V. MPPT The system controls the MPPT circuit to begin MPPT operation. For a schematic diagram of the connection between the MPPT control circuit and the piezoelectric energy harvesting circuit provided in this embodiment of the invention, please refer to [link to relevant documentation]. Figure 7 .from Figure 7 As can be seen, the piezoelectric power supply in the piezoelectric energy harvesting circuit is an AC power source. The piezoelectric energy harvesting circuit also includes a rectifier, which comprises a first-stage negative voltage converter and a second-stage active diode. The second-stage active diode includes a comparator COMP and a transistor M1. The first input terminal of the first-stage negative voltage converter is connected to the piezoelectric power supply, and the second input terminal is connected to ground. The first output terminal of the first-stage negative voltage converter is connected to the source terminal of the transistor M1 included in the second-stage active diode, and the second output terminal is connected to ground. The negative input terminal of the comparator in the second-stage active diode is connected to the source terminal of M1, the positive input terminal is connected to the drain terminal of M1, and the output terminal of the comparator is connected to the gate terminal of M1. Optionally, M1 is a PMOS transistor. In this embodiment of the invention, the duty cycle monitoring circuit monitors the comparison signal generated by the rectifier as the comparison signal V generated by the comparator in the second-stage active diode included in the rectifier. COMP .

[0102] See also Figure 7 The piezoelectric energy harvesting circuit also includes a capacitor C. REC C RECOne end is connected to the drain of transistor M1, and the other end is grounded.

[0103] Specifically, the rectifier generates the voltage signal V from the voltage power supply. P Cosmetic procedures include:

[0104] The first-stage negative voltage converter converts the negative half-cycle signal of the voltage signal into a positive half-cycle signal, and sends the positive half-cycle signal to the second-stage active diode.

[0105] The second-stage active diode converts the positive half-cycle signal into a DC voltage signal V. REC and the comparator's output signal V COMP The signal is sent to the monitoring input terminal of the duty cycle monitoring circuit.

[0106] Capacitor C REC Its function is to process DC voltage signal V REC Perform filtering.

[0107] Understandably, the MPPT power stage in the piezoelectric energy harvesting circuit is the downstream load of the rectifier. The MPPT power stage in the piezoelectric energy harvesting circuit is controlled according to the maximum power point voltage V. MPPT The operation is performed so that the input impedance of the downstream load of the piezoelectric rectifier is adjusted to the optimal load impedance in order to achieve maximum power point tracking.

[0108] Figure 8 This is a schematic diagram of the relevant waveforms of the adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition provided in an embodiment of the present invention. In this embodiment, the enable signal E... N_MPPT V is the start signal for the MPPT module. COMP The comparison signal generated by the rectifier, signal V1 is V COMP The tracking signal during the signal activation period, signal V2 is V COMP The tracking signal during the off period. See also Figure 4 At time t0, V N This will generate a high pulse, turning on the first NMOS transistor Q3 and the second NMOS transistor Q4, which respectively affect V. DET1 and V DET2 Voltage is released, V DET1 and V DET2 The value is restored to 0. Please continue reading. Figure 8 The first charging capacitor C1 starts charging from time t0, after a short pulse V N After the signal is reset to zero, charging begins during the active low period of the V1 signal. The voltage value V on the first charging capacitor C1 is... DET1 The first monitoring signal is held at time t1; the second charging capacitor C2 also passes through a short pulse V at time t0. NThe signal is set to zero, and then charging begins from time t1 during the active low period of the V2 signal. The voltage value V on the second charging capacitor C2 is... DET2 The second monitoring signal is held at time t2, and its magnitude is related to V. COMP The duty cycles for on and off are positively correlated. Then, the sampling signal generation circuit samples V... DET1 and V DET2 The signal is selected, divided, and compared. The voltage division ratio of the voltage divider circuit constrains the deviation of the duty cycle from 50%. Optionally, taking a voltage division ratio of 0.8 as an example, this constrains a deviation of ±5.5%, meaning that when the duty cycle is greater than 55.5% and less than 44.5%, the comparison result should be V. DET1 Greater than 0.8*V DET2 At this time, the V generated by the low pulse generation circuit SAMPLE The signal is active low. See also Figure 1 and Figure 2 The sample-and-hold circuit begins to operate on the open-circuit voltage V of the power supply. P Sampling is performed to determine the maximum power point voltage signal V. MPPT And control the MPPT power stage in the piezoelectric energy harvesting circuit according to the maximum power point voltage V. MPPT Perform maximum power point tracking. From E N_MPPT From the start of the signal being active high to the time it takes for the system to receive the sampled signal, a total of 1.5 cycles are required.

[0109] Similarly, if V is obtained in the above process DET1 The value is less than 0.8*V DET2 Then the V generated by the low pulse generation circuit SAMPLE When the signal is high, the duty cycle of the comparison signal generated by the rectifier is large, and the MPPT circuit operates efficiently. Open-circuit sampling and MPPT operation are not performed in this case. (See [link]). Figure 1 and Figure 2 The sample-and-hold circuit does not operate.

[0110] It is understood that the adaptive sampling open-circuit voltage (MPPT) method for piezoelectric energy harvesting provided in this embodiment of the invention can also be applied to adaptive sampling open-circuit voltage for thermoelectric energy harvesting. Specifically, in the fixed-pulse-frequency PWM (Pulse Width Modulation) control mode used in the thermoelectric energy harvesting circuit, the duty cycle monitoring circuit 10 in the MPPT control circuit is used to monitor the drive signal of the main power switch in the MPPT power stage in real time, generating a monitoring signal characterizing the duty cycle of the main power switch drive signal; the monitoring signal includes a first monitoring signal V. DET1 Second monitoring signal V DET2 The first monitoring signal V DET1Corresponding to the conduction pulse width of the main power switch drive signal, the second monitoring signal V DET2 Corresponding to the turn-off pulse width of the main power switch drive signal; using the sampling signal generation circuit 20 in the MPPT control circuit, compare the first monitoring signal V. DET1 Second monitoring signal V DET2 Select the first monitoring signal V DET1 Second monitoring signal V DET2 The larger value in is used as the first output signal V DET_Max Select the first monitoring signal V DET1 Second monitoring signal V DET2 The smaller value in is used as the second output signal V DET_Min According to the first output signal V DET_Max Second output signal V DET_Min Output comparison signal V MPP_COMP For the comparison signal V MPP_COMP When a comparison signal V is detected, a judgment is made. MPP_COMP A low-level pulse is generated as the sampling signal V on the falling edge. SAMPLE If a sampled signal V is generated SAMPLE Using the sample-and-hold circuit 30 in the MPPT control circuit, the open-circuit voltage V of the voltage power supply in the thermoelectric energy harvesting circuit is measured. P Sampling is performed to determine the maximum power point voltage V. MPPT The MPPT power stage in the thermoelectric energy harvesting circuit is controlled according to the maximum power point voltage V. MPPT Work is performed to achieve maximum power point tracking.

[0111] Figure 9 This is a schematic diagram of the simulation waveforms related to the adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition provided in this embodiment of the invention. Figure 9 As shown, every 128 piezoelectric vibration cycles, V COMP The duty cycle is monitored once, and the MPPT operation is determined based on the monitoring results. The waveform within the dashed box in the figure is magnified to show the relevant simulation waveform of the first monitoring action. E N_MPPT The signal is an enable signal, when E N_MPPT When the signal is high, for V COMP The duty cycle is then monitored. First, V N Generate a high-level pulse for V DET1 and V DET2 The residual voltage is released. Then, V1 and V2 begin tracking V. COMP The signal is turned on and off, V DET1 and V DET2The signals begin charging separately. Subsequently, the sampling signal generation circuit selects, divides, and compares them. In the simulation example, V... COMP The duty cycle is set to 44%, the voltage divider ratio is set to 0.8, and the comparator circuit is set to V. DET1 and 0.8*V DET2 The values ​​are compared, and the comparison result is V. DET1 Greater than 0.8*V DET2 Therefore, V is obtained in the second piezoelectric vibration cycle. SAMPLE The signal is active low. Finally, as... Figure 1 and Figure 2 As shown, the sample-and-hold circuit starts with the open-circuit voltage V of the power supply. P Sampling is performed to determine the maximum power point voltage signal V. MPPT And control the MPPT power stage in the piezoelectric energy harvesting circuit according to the maximum power point voltage V. MPPT Perform maximum power point tracking.

[0112] Secondly, corresponding to the above method embodiments, this invention also provides an adaptive sampling open-circuit voltage MPPT system suitable for piezoelectric energy acquisition, such as... Figure 2 As shown, it may include:

[0113] Duty cycle monitoring circuit 10, sampling signal generation circuit 20, and sample-and-hold circuit 30; wherein,

[0114] Duty cycle monitoring circuit 10 is used to monitor in real time the comparison signal V generated by the rectifier in the piezoelectric energy harvesting circuit during each monitoring cycle. COMP Generates a characterization comparison signal V COMP The duty cycle monitoring signal; the monitoring signal includes: the first monitoring signal V DET1 Second monitoring signal V DET2 The first monitoring signal V DET1 Comparison signal V COMP The conduction pulse width corresponds to the second monitoring signal V. DET2 For comparison signal V COMP The width of the turn-off pulse corresponds to;

[0115] The sampling signal generation circuit 20 is used to compare the first monitoring signal V. DET1 Second monitoring signal V DET2 Select the first monitoring signal V DET1 Second monitoring signal V DET2 The larger value in is used as the first output signal V DET_Max Select the first monitoring signal V DET1 Second monitoring signal V DET2 The smaller value in is used as the second output signal V DET_MinAccording to the first output signal V DET_Max Second output signal V DET_Min Output comparison signal V MPP_COMP For the comparison signal V MPP_COMP When a comparison signal V is detected, a judgment is made. MPP_COMP A low-level pulse is generated as the sampling signal V on the falling edge. SAMPLE ;

[0116] The sample-and-hold circuit 30 is used to, if a sampled signal V is generated SAMPLE The open-circuit voltage V of the piezoelectric power supply in the piezoelectric energy harvesting circuit. P Sampling is performed to determine the maximum power point voltage V. MPPT The MPPT power stage in the piezoelectric energy harvesting circuit is controlled according to the maximum power point voltage V. MPPT Work is performed to achieve maximum power point tracking.

[0117] Understandably, the detailed working principle of the duty cycle monitoring circuit 10 can be found in the working process corresponding to S1 in the method embodiment provided in the first aspect, the detailed working principle of the sampling signal generation circuit 20 can be found in the working process corresponding to S2 in the method embodiment provided in the first aspect, and the detailed working principle of the sample and hold circuit 30 can be found in the working process corresponding to S3 in the method embodiment provided in the first aspect. They will not be elaborated on here.

[0118] This invention utilizes a duty cycle monitoring circuit to monitor the duty cycle of the comparison signal generated by the rectifier. Combined with a sampling signal generation circuit, the monitored signal is analyzed to determine whether to generate a sampling signal, thereby adjusting the MPPT control circuit and improving the efficiency of the piezoelectric energy harvesting circuit. When the duty cycle is 50%, the theoretical tracking efficiency of the MPPT circuit is 100%. The greater the deviation of the duty cycle from 50%, the lower the tracking efficiency of the MPPT circuit. In this case, the holding circuit re-samples the open-circuit voltage of the piezoelectric power supply to determine the maximum power point voltage and perform maximum power point tracking. Through this method, the open-circuit sampling and MPPT control circuits can be adjusted as needed based on the duty cycle signal generated by the rectifier, achieving adaptive control of open-circuit sampling and MPPT. When the duty cycle approaches 50%, the relevant circuit for open-circuit voltage sampling is shut down, saving losses in the piezoelectric energy harvesting device, reducing energy waste, and improving energy collection efficiency.

[0119] It should be noted that, in the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0120] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. An adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition, applied to an MPPT control circuit, characterized in that, include: Using the duty cycle monitoring circuit (10) in the MPPT control circuit, the comparison signal V generated by the rectifier in the piezoelectric energy acquisition circuit in each monitoring cycle is monitored in real time. COMP Generates a characterization comparison signal V COMP The duty cycle monitoring signal; the monitoring signal includes: a first monitoring signal V DET1 Second monitoring signal V DET2 The first monitoring signal V DET1 Comparison signal V COMP The conduction pulse width corresponds to the second monitoring signal V. DET2 Comparison signal V COMP The width of the turn-off pulse corresponds to; Using the sampling signal generation circuit (20) in the MPPT control circuit, the first monitoring signal V is compared. DET1 Second monitoring signal V DET2 Select the first monitoring signal V DET1 Second monitoring signal V DET2 The larger value in is used as the first output signal V DET_Max Select the first monitoring signal V DET1 Second monitoring signal V DET2 The smaller value in is used as the second output signal V DET_Min According to the first output signal V DET_Max Second output signal V DET_Min Output comparison signal V MPP_COMP For the comparison signal V MPP_COMP When a comparison signal V is detected, a judgment is made. MPP_COMP A low-level pulse is generated at the falling edge of the signal as the sampling signal V. SAMPLE ; If a sampling signal V is generated SAMPLE Using the sample-and-hold circuit (30) in the MPPT control circuit, the open-circuit voltage V of the piezoelectric power supply in the piezoelectric energy acquisition circuit is measured. P Sampling is performed to determine the maximum power point voltage V. MPPT The MPPT power stage in the piezoelectric energy harvesting circuit is controlled according to the maximum power point voltage V. MPPT Work is performed to achieve maximum power point tracking.

2. The adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition according to claim 1, characterized in that, The duty cycle monitoring circuit (10) includes: The monitoring and control signal generation circuit (101) and the capacitor charging and discharging circuit (102) are connected in sequence.

3. The adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition according to claim 2, characterized in that, Using the duty cycle monitoring circuit (10) in the MPPT control circuit, the comparison signal V generated by the rectifier in the piezoelectric energy acquisition circuit in each monitoring cycle is monitored in real time. COMP Generates a characterization comparison signal V COMP The duty cycle monitoring signal includes: The monitoring and control signal generation circuit (101) enables the signal E. N_MPPT Under the control of [the system], based on the comparison signal V generated by the rectifier in the piezoelectric energy acquisition circuit within a monitoring cycle, [the system]... COMP This generates monitoring and control signals; The capacitor charging and discharging circuit (102) generates a comparison signal V based on the monitoring and control signal. COMP The first monitoring signal V for duty cycle status DET1 Second monitoring signal V DET2 .

4. The adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition according to claim 1, characterized in that, The first monitoring signal V DET1 The comparison signal V generated by the rectifier COMP It is proportional to the conduction pulse width.

5. The adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition according to claim 1, characterized in that, The second monitoring signal V DET2 The comparison signal V generated by the rectifier COMP It is proportional to the width of the turn-off pulse.

6. The adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition according to claim 1, characterized in that, The sampling signal generation circuit (20) includes: The voltage selection circuit (201), voltage divider circuit (202), comparator circuit (203), and low pulse generation circuit (204) are connected in sequence.

7. The adaptive sampling open-circuit voltage MPPT method for piezoelectric energy acquisition according to claim 6, characterized in that, Using the sampling signal generation circuit (20) in the MPPT control circuit, the first monitoring signal V is compared. DET1 Second monitoring signal V DET2 Select the first monitoring signal V DET1 Second monitoring signal V DET2 The larger value in is used as the first output signal V DET_Max Select the first monitoring signal V DET1 Second monitoring signal V DET2 The smaller value in is used as the second output signal V DET_Min According to the first output signal V DET_Max Second output signal V DET_Min Output comparison signal V MPP_COMP For the comparison signal V MPP_COMP When a comparison signal V is detected, a judgment is made. MPP_COMP A low-level pulse is generated at the falling edge of the signal as the sampling signal V. SAMPLE ,include: The voltage selection circuit (201) selects the first monitoring signal V. DET1 Second monitoring signal V DET2 To perform the detection, select the first monitoring signal V. DET1 Second monitoring signal V DET2 The larger value in is used as the first output signal V DET_Max And output to the voltage divider circuit (202) to select the first monitoring signal V. DET1 Second monitoring signal V DET2 The smaller value in is used as the second output signal V DET_Min And output to the comparator circuit (203); The voltage divider circuit (202) divides the first output signal V DET_Max The voltage is divided to produce a voltage V. Div_Max ; The comparator circuit (203) compares the second output signal V. DET_Min and voltage divider V Div_Max Compare and output comparison signal V MPP_COMP ; The low-pulse generation circuit (204) compares the signal V. MPP_COMP When a comparison signal V is detected, a judgment is made. MPP_COMP A low-level pulse is generated at the falling edge of the signal as the sampling signal V. SAMPLE .

8. An adaptive sampling open-circuit voltage MPPT system suitable for piezoelectric energy harvesting, characterized in that, include: The circuit includes a duty cycle monitoring circuit (10), a sampling signal generation circuit (20), and a sample-and-hold circuit (30); among which, The duty cycle monitoring circuit (10) is used to monitor in real time the comparison signal V generated by the rectifier in the piezoelectric energy acquisition circuit during each monitoring cycle. COMP Generates a characterization comparison signal V COMP The duty cycle monitoring signal; the monitoring signal includes: a first monitoring signal V DET1 Second monitoring signal V DET2 The first monitoring signal V DET1 Comparison signal V COMP The conduction pulse width corresponds to the second monitoring signal V. DET2 For comparison signal V COMP The width of the turn-off pulse corresponds to; The sampling signal generation circuit (20) is used to compare the first monitoring signal V. DET1 Second monitoring signal V DET2 Select the first monitoring signal V DET1 Second monitoring signal V DET2 The larger value in is used as the first output signal V DET_Max Select the first monitoring signal V DET1 Second monitoring signal V DET2 The smaller value in is used as the second output signal V DET_Min According to the first output signal V DET_Max Second output signal V DET_Min Output comparison signal V MPP_COMP For the comparison signal V MPP_COMP When a comparison signal V is detected, a judgment is made. MPP_COMP A low-level pulse is generated at the falling edge of the signal as the sampling signal V. SAMPLE ; The sample-and-hold circuit (30) is used to, if a sample signal V is generated SAMPLE The open-circuit voltage V of the piezoelectric power supply in the piezoelectric energy harvesting circuit. P Sampling is performed to determine the maximum power point voltage V. MPPT The MPPT power stage in the piezoelectric energy harvesting circuit is controlled according to the maximum power point voltage V. MPPT Work is performed to achieve maximum power point tracking.

9. An adaptive sampling open-circuit voltage MPPT system for piezoelectric energy acquisition according to claim 8, characterized in that, The duty cycle monitoring circuit (10) includes: The monitoring and control signal generation circuit (101) and the capacitor charging and discharging circuit (102) are connected in sequence; among them, The monitoring and control signal generation circuit (101) includes: a frequency divider and a frequency division control circuit; wherein, The input terminal of the frequency divider is connected to the first input terminal of the frequency division control circuit, and is connected to the comparison signal V generated by the rectifier. COMP The output terminal is connected to the second input terminal of the frequency division control circuit; The third input terminal of the frequency division control circuit is connected to the enable signal E. N_MPPT ; The capacitor charging and discharging circuit (102) includes: a first current source I1, a second current source I2, a first PMOS transistor Q1, a second PMOS transistor Q2, a first NMOS transistor Q3, a second NMOS transistor Q4, a first charging capacitor C1, and a second charging capacitor C2; wherein, The input terminal of the first current source I1 is connected to the power supply voltage, and the output terminal is connected to the source of the first PMOS transistor Q1. The input terminal of the second current source I2 is connected to the power supply voltage, and the output terminal is connected to the source of the second PMOS transistor Q2; The gate of the first PMOS transistor Q1 is connected to the first output terminal of the frequency division control circuit, and the drain is connected to the first terminal of the first charging capacitor C1. The gate of the second PMOS transistor Q2 is connected to the second output terminal of the frequency division control circuit, and the drain is connected to the first terminal of the second charging capacitor C2. The source of the first NMOS transistor Q3 is grounded, its gate is connected to the third output terminal of the frequency division control circuit, and its drain is connected to the drain of the first PMOS transistor Q1. The source of the second NMOS transistor Q4 is grounded, its gate is connected to the third output terminal of the frequency division control circuit, and its drain is connected to the drain of the second PMOS transistor Q2. The second terminal of the first charging capacitor C1 is connected to the source of the first NMOS transistor Q3; the voltage across the first charging capacitor C1 serves as the first monitoring signal V. DET1 ; The second terminal of the second charging capacitor C2 is connected to the source of the second NMOS transistor Q4; the voltage across the second charging capacitor C2 serves as the second monitoring signal V. DET2 .

10. An adaptive sampling open-circuit voltage MPPT system for piezoelectric energy acquisition according to claim 8, characterized in that, The sampling signal generation circuit (20) includes: The circuit includes a voltage selection circuit (201), a voltage divider circuit (202), a comparator circuit (203), and a low-pulse generation circuit (204); among which, The first input terminal of the voltage selection circuit (01) is connected to the first monitoring signal V. DET1 The second input terminal is connected to the second monitoring signal V. DET2 The first output terminal is connected to the input terminal of the voltage divider circuit (202), and the second output terminal is connected to the inverting input terminal of the comparator circuit (203). The output terminal of the voltage divider circuit (202) is connected to the non-inverting input terminal of the comparator circuit (203); The output terminal of the comparator circuit (203) is connected to the input terminal of the low pulse generation circuit (204); The output terminal of the low pulse generation circuit (204) serves as the output terminal of the sampling signal generation circuit (20).

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