A sampling circuit and its system

Abstract

Embodiments of the present invention disclose a sampling circuit and its system. The sampling circuit is applied to a totem-pole bridgeless circuit and includes: a voltage acquisition module configured to acquire and output the positive-polarity voltage and the negative-polarity voltage of an AC input power supply; a polarity control module configured to output a polarity control signal in response to the positive-polarity voltage and the negative-polarity voltage; a differential operation module configured to output a first differential signal and a second differential signal in response to a sampling signal; a signal gating module configured to select and output the first differential signal or the second differential signal under the control of the polarity control signal; and an analog-to-digital conversion module configured to convert the first differential signal or the second differential signal into a corresponding digital signal. By the above method, the embodiments of the present invention can sample the input voltage of the totem-pole bridgeless circuit by using one ADC, reducing the chip cost of the sampling circuit and the volume of the sampling circuit.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of electronic technology, and in particular, to a sampling circuit and a system thereof. Background Art

[0002] In an energy conversion system, the conversion efficiency of a power supply is very important. Wide bandgap power semiconductors, such as gallium nitride (GaN) and silicon carbide (SiC), have recently gained favor in power conversion applications due to their excellent switching characteristics and continuously improving quality. Benefiting from the advantages of gallium nitride and silicon carbide, the totem-pole bridgeless circuit, as a type of bridgeless circuit, has advantages such as a simple circuit structure and high conversion efficiency, and has been increasingly widely applied in recent years.

[0003] Currently, the sampling of the input voltage of a totem-pole bridgeless circuit usually requires two analog-to-digital converters (ADCs). One ADC samples the input positive voltage, and the other ADC samples the input negative voltage, which undoubtedly increases the chip cost. Summary of the Invention

[0004] To solve the above technical problems, an aspect of an embodiment of the present invention is to provide a sampling circuit applied to a totem-pole bridgeless circuit. The totem-pole bridgeless circuit includes an AC input power supply and an input inductor. One end of the input inductor is connected to the positive pole of the AC input power supply. The sampling circuit includes: a voltage acquisition module configured to acquire and output the positive voltage and negative voltage of the AC input power supply. The voltage acquisition module has: a first sampling terminal connected to the positive pole of the AC input power supply and a second sampling terminal connected to the negative pole of the AC input power supply; a polarity control module configured to output a polarity control signal in response to the positive voltage and the negative voltage. The first input terminal of the polarity control module is connected to the first output terminal of the voltage acquisition module, and the second input terminal of the polarity control module is connected to the second output terminal of the voltage acquisition module; a differential operation module configured to output a first differential signal and a second differential signal in response to a sampling signal; a signal selection module controlled by the polarity control signal to selectively output the first differential signal or the second differential signal. The signal selection module is configured to select the first differential signal when the polarity control signal is at a high level and select the second differential signal when the polarity control signal is at a low level; an analog-to-digital conversion module configured to convert the first differential signal or the second differential signal into a corresponding digital signal. The input terminal of the analog-to-digital conversion module is connected to the output terminal of the signal selection module.

[0005] In some embodiments, the voltage acquisition module includes a first resistor, a second resistor, a third resistor, and a fourth resistor. Among them, one end of the first resistor is connected to the positive pole of the AC input power supply, and the other end of the first resistor is connected to one end of the second resistor to form a first connection point, and the other end of the second resistor is grounded; one end of the third resistor is connected to the negative pole of the AC input power supply, and the other end of the third resistor is connected to one end of the fourth resistor to form a second connection point, and the other end of the fourth resistor is grounded.

[0006] In some embodiments, when the sampling signal is the positive-polarity voltage and the negative-polarity voltage, the first differential signal is a first voltage differential signal, and the second differential signal is a second voltage differential signal. The differential operation module includes: a first differential unit configured to output the first voltage differential signal in response to the positive-polarity voltage and the negative-polarity voltage, and the input end of the first differential unit is connected to the first output end of the voltage acquisition module; a second differential unit configured to output the second voltage differential signal in response to the positive-polarity voltage and the negative-polarity voltage, and the input end of the second differential unit is connected to the second output end of the voltage acquisition module.

[0007] In some embodiments, when the sampling signal is the inductor current of the input inductor, the first differential signal is a first current differential signal, and the second differential signal is a second current differential signal. The differential operation module includes: a current conversion unit configured to output a first voltage and a second voltage in response to the inductor current, and the input end of the current conversion unit is connected to the other end of the input inductor; a third differential unit configured to output the first current differential signal in response to the first voltage and the second voltage, and the input end of the third differential unit is connected to the first output end of the current conversion unit; a fourth differential unit configured to output the second current differential signal in response to the first voltage and the second voltage, and the input end of the fourth differential unit is connected to the second output end of the current conversion unit.

[0008] In some embodiments, the first differential unit is a first operational amplifier, the non-inverting input terminal of the first operational amplifier is connected to the first connection point, and the inverting input terminal of the first operational amplifier is connected to the second connection point. The second differential unit is a second operational amplifier, the non-inverting input terminal of the second operational amplifier is connected to the second connection point, and the inverting input terminal of the second operational amplifier is connected to the first connection point.

[0009] In some embodiments, the current conversion unit includes a DC input power supply, a Hall sensor, a fifth resistor, a sixth resistor, and a first capacitor. Wherein, the input end of the Hall sensor is connected to the other end of the input inductor, and the first output end of the Hall sensor outputs the first voltage; one end of the fifth resistor is connected to the second output end of the Hall sensor and one end of the first capacitor, and the other end of the fifth resistor is connected to one end of the sixth resistor to form a third connection point, and the third connection point outputs the second voltage; the other end of the sixth resistor is connected to the other end of the first capacitor, one end of the first capacitor is connected to the DC input power supply, and the other end of the first capacitor is grounded.

[0010] In some embodiments, the third differential unit is a first operational amplifier. The non-inverting input terminal of the first operational amplifier is connected to the first output terminal of the Hall sensor, and the inverting input terminal of the first operational amplifier is connected to the third connection point; the fourth differential unit is a second operational amplifier. The non-inverting input terminal of the second operational amplifier is connected to the third connection point, and the inverting input terminal of the second operational amplifier is connected to the first output terminal of the Hall sensor.

[0011] In some embodiments, the polarity control module includes a first comparator and a filter. Wherein, the non-inverting input terminal of the first comparator is connected to the first connection point, and the inverting input terminal of the first comparator is connected to the second connection point; the output terminal of the first comparator is connected to the input terminal of the filter.

[0012] In some embodiments, the signal gating module is a single-pole double-throw switch. The control terminal of the single-pole double-throw switch is connected to the output terminal of the filter, the first input terminal of the single-pole double-throw switch is connected to the output terminal of the first operational amplifier, and the second input terminal of the single-pole double-throw switch is connected to the output terminal of the second operational amplifier.

[0013] In some embodiments, the analog-to-digital conversion module includes an analog-to-digital converter and a second comparator. Wherein, the input terminal of the analog-to-digital converter is connected to the output terminal of the single-pole double-throw switch; the non-inverting input terminal of the second comparator is connected to the output terminal of the single-pole double-throw switch, and the inverting input terminal of the second comparator is connected to the output terminal of the reference voltage source.

[0014] To solve the above technical problems, another technical solution adopted in the embodiments of the present invention is: to provide a sampling system, characterized by including: a totem-pole bridgeless circuit, the totem-pole bridgeless circuit includes an AC input power supply and an input inductor; and a sampling circuit as described above.

[0015] The beneficial effects of the embodiments of the present invention are as follows: Different from the prior art, the embodiments of the present invention can realize sampling the input voltage of a totem-pole bridgeless circuit by using one ADC, which reduces the chip cost of the sampling circuit and the volume of the sampling circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 shows a circuit topology diagram of a totem-pole bridgeless circuit;

[0017] Figure 2 is a schematic structural diagram of a sampling circuit provided by an embodiment of the present invention;

[0018] Figure 3 is a circuit topology diagram of the first sampling circuit provided by an embodiment of the present invention;

[0019] Figure 4 is a waveform diagram obtained by applying the first sampling circuit in an embodiment of the present invention;

[0020] Figure 5 is a waveform diagram obtained by applying the first sampling circuit after considering polarity filtering in an embodiment of the present invention;

[0021] Figure 6 is a circuit topology diagram of the second sampling circuit provided by an embodiment of the present invention;

[0022] Figure 7 is a waveform diagram obtained by applying the second sampling circuit in an embodiment of the present invention;

[0023] Figure 8 is a schematic structural diagram of a sampling system provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those of ordinary skill in the art can make several modifications and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0025] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0026] Figure 1 shows a circuit topology diagram of a totem-pole bridgeless circuit, and the totem-pole bridgeless circuit includes an input unit 110, a first bridge arm unit 120, a second bridge arm unit 130, and a load unit 140.

[0027] Among them, the input unit 110 includes an input AC power supply AC and an input inductor L. The positive pole of the input AC power supply AC is connected to one end of the input inductor L.

[0028] The first bridge arm unit 120 includes a first switching transistor Q1 and a second switching transistor Q2. The drain of the first switching transistor Q1 is connected to the source of the second switching transistor Q2. The other end of the input inductor L is connected to the drain of the first switching transistor Q1 and the source of the second switching transistor Q2.

[0029] The second bridge arm unit 130 includes a third switching transistor SR1 and a fourth switching transistor SR2. The drain of the fourth switching transistor SR2 is connected to the drain of the second switching transistor Q2. The source of the fourth switching transistor SR2 is connected to the drain of the third switching transistor SR1. The source of the third switching transistor SR3 is connected to the source of the first switching transistor Q1; the negative pole of the AC input power supply AC is connected to the drain of the third switching transistor SR1 and the source of the fourth switching transistor SR2.

[0030] The load unit 140 includes a filter capacitor C1 and a load resistor RL. One end of the filter capacitor C1 is connected to the drain of the fourth switching transistor SR2. The other end of the filter capacitor C1 is connected to the source of the third switching transistor SR1. The load resistor RL is connected in parallel across both ends of the filter capacitor C1.

[0031] A common digital control system for a totem-pole bridgeless circuit based on Continuous Current Mode (CCM) samples the positive-polarity voltage V ACL and negative-polarity voltage V ACN , the input inductor current I CS and output voltage V FB signals of the AC input power supply AC through a sampling circuit, and then converts the analog signals into digital signals through an ADC for loop calculation and processing in the digital domain. The digital control system usually adopts a double-loop control. The current loop is the inner loop, which controls the input current waveform to follow the input voltage waveform; the voltage loop is the outer loop, which adjusts the output voltage to be stable.

[0032] However, usually two ADCs are required for sampling the input voltage. One ADC samples the positive-polarity voltage V ACL , and the other ADC samples the negative-polarity voltage V ACN .

[0033] In addition, there is another implementation method, that is, first superimpose a certain bias voltage on the V ACL -V ACN differential input to become a positive voltage, and then sample the positive voltage through a single ADC. However, this circuit is relatively complex and will introduce additional sampling errors due to the introduction of the bias voltage.

[0034] To solve the above problems, based on the above totem pole bridgeless circuit, the present invention provides a sampling circuit, the structural diagram of which is shown in FIG. Figure 2 As shown, the sampling circuit includes a voltage acquisition module 210, a polarity control module 240, a differential operation module 300, a signal gating module 250 and an analog-to-digital conversion module 260, wherein:

[0035] The voltage acquisition module 210 is configured to acquire and output the positive polarity voltage V of the AC input power supply AC of the input unit 110 of the totem pole bridgeless circuit. ACL and negative voltage V ACN The first sampling terminal of the voltage acquisition module 210 is connected to the positive electrode of the AC input power supply AC, and the second sampling terminal of the voltage acquisition module 210 is connected to the negative electrode of the AC input power supply AC.

[0036] The polarity control module 240 is configured to respond to the positive polarity voltage V ACL and negative voltage V ACN The polarity control signal is outputted. The first input terminal of the polarity control module 240 is connected to the first output terminal of the voltage acquisition module 210 , and the second input terminal of the polarity control module 240 is connected to the second output terminal of the voltage acquisition module 210 .

[0037] The differential operation module 300 is configured to output a first differential signal and a second differential signal in response to the sampling signal.

[0038] The signal gating module 250 is configured to select and output the first differential signal or the second differential signal in response to the polarity control signal POLARITY; in this embodiment, the signal gating module 250 is configured to output the first differential signal when the polarity control signal POLARITY is at a high level, and to output the second differential signal when the polarity control signal POLARITY is at a low level. The first input end of the signal gating module 250 is connected to the first output end of the differential operation module 300, and the second input end of the signal gating module 250 is connected to the second output end of the differential operation module 300. The analog-to-digital conversion module 260 is configured to convert the first differential signal or the second differential signal into a corresponding digital signal, and the input end of the analog-to-digital conversion module 260 is connected to the output end of the signal gating module 250.

[0039] In the embodiment of the present invention, two specific implementations are proposed based on different sampling signals. When the sampling signal is the positive polarity voltage V input by the AC input power supply AC of the input unit 110 of the totem pole bridgeless circuit, ACL and negative voltage V ACN When the sampling circuit is Figure 3 As shown,

[0040] Specifically, the voltage acquisition module 210 includes a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4, wherein one end of the first resistor R1 is connected to the positive electrode of the AC input power supply AC, the other end of the first resistor R1 is connected to one end of the second resistor R2 to form a first connection point A, and the other end of the second resistor R2 is grounded.

[0041] One end of the third resistor R3 is connected to the negative electrode of the AC input power source AC, the other end of the third resistor R3 is connected to one end of the fourth resistor R4 to form a second connection point B, and the other end of the fourth resistor R4 is grounded.

[0042] It should be noted that when the sampling signal is a positive polarity voltage V ACL and negative voltage V ACN , the first differential signal output by the differential operation module 300 is a first voltage differential signal V AC1 , the second differential signal is a second voltage differential signal V AC2 .

[0043] When the sampling signal is a positive voltage V ACL and negative voltage V ACN When the differential operation module 300 includes a circuit configured to respond to the positive polarity voltage V ACL and negative voltage V ACN Output the first voltage differential signal V AC1 The first differential unit 220, the input end of the first differential unit 220 is connected to the first output end of the voltage acquisition module 210; and is configured to respond to the positive polarity voltage V ACL and negative voltage V ACN Output the second voltage differential signal V AC2 The second differential unit 230 has an input end connected to the second output end of the voltage acquisition module 210 .

[0044] Specifically, the first differential unit 220 is a first operational amplifier U1 , a non-inverting input terminal of the first operational amplifier U1 is connected to a first connection point A, and an inverting input terminal of the first operational amplifier U1 is connected to a second connection point B.

[0045] The second differential unit is a second operational amplifier U2 . The non-inverting input terminal of the second operational amplifier U2 is connected to the second connection point B, and the inverting input terminal of the second operational amplifier U2 is connected to the first connection point A.

[0046] Specifically, the polarity control module 240 includes a first comparator U3 and a filter U4. Among them, the non-inverting input terminal of the first comparator U3 is connected to the first connection point A, and the inverting input terminal of the first comparator U3 is connected to the second connection point B; the output terminal of the first comparator U3 is connected to the input terminal of the filter U4.

[0047] Specifically, the signal gating module 250 is a single-pole double-throw switch K1. The control terminal of the single-pole double-throw switch K1 is connected to the output terminal of the filter U4. The first input terminal of the single-pole double-throw switch K1 is connected to the output terminal of the first operational amplifier U1, and the second input terminal of the single-pole double-throw switch K1 is connected to the output terminal of the second operational amplifier U2.

[0048] Specifically, the analog-to-digital conversion module 260 includes an analog-to-digital converter U5 and a second comparator U6. Among them, the input terminal of the analog-to-digital converter U5 is connected to the output terminal of the single-pole double-throw switch K1; the non-inverting input terminal of the second comparator U6 is connected to the output terminal of the single-pole double-throw switch K1, and the inverting input terminal of the second comparator U6 is connected to the output terminal of the reference voltage source V REF

[0049] The specific implementation principle is that the first comparator U3 compares the positive-polarity voltage V ACL and the negative-polarity voltage V ACN collected by the voltage acquisition module 210, and outputs a polarity control signal POLARITY. The first operational amplifier U1 samples the differential voltage V ACL -V ACN signal and outputs the V AC1 signal; the second operational amplifier U2 samples the differential voltage V ACN -V ACL signal and outputs the V AC2 signal.

[0050] The single-pole double-throw switch K1 selects to conduct the connection between the first operational amplifier U1 or the second operational amplifier U2 and the analog-to-digital converter U5 according to the level of the polarity control signal POLARITY. In this embodiment, when V ACL >V ACN , the polarity control signal POLARITY is at a high level, and the single-pole double-throw switch K1 conducts the connection between the first operational amplifier U1 and the analog-to-digital converter U5, and the input signal of the analog-to-digital converter U5 is the V AC1 signal; when V ACL <V ACN , the polarity control signal POLARITY is at a low level, and the single-pole double-throw switch K1 conducts the connection between the second operational amplifier and the analog-to-digital converter U5, and the input signal of the analog-to-digital converter U5 is the V AC2 signal.

[0051] ​The waveform diagram obtained by applying the first sampling circuit described above is as follows Figure 4 shown, where the V AC1 signal represents the V of the positive half-cycle of the alternating current ACL -V ACN signal, and the V AC2 signal represents the V of the negative half-cycle of the alternating current ACN -V ACL signal. Together, they form the absolute value signal of V AC |V AC |, that is, |V ACL -V ACN |.

[0052] However, during the zero-crossing period of the input alternating current, due to the existence of interference signals, the output of the first comparator U3 may have the phenomenon of multiple level reversals during the zero-crossing period of the input alternating current. In order to filter out the signals with repeated level reversals, a certain digital filter U4 is added to the output of the first comparator U3.

[0053] Due to the addition of the filter U4, the level inversion of the polarity control signal POLARITY may be delayed compared to the actual zero-crossing of the alternating voltage as Figure 5 shown. In this way, the actually obtained |V AC | has a certain distortion. Since the PWM output of the control circuit of the totem-pole bridgeless circuit needs to turn off the output during the zero-crossing period of the input alternating current, the certain distortion of |V AC | will not affect the power factor correction function of the totem-pole circuit.

[0054] When the sampling signal is the inductor current of the input inductor L, the circuit topology diagram of the sampling circuit is as Figure 6 shown, where

[0055] Specifically, the voltage acquisition module 210 includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. Among them, one end of the first resistor R1 is connected to the positive pole of the AC input power supply AC, and the other end of the first resistor R1 is connected to one end of the second resistor R2 to form a first connection point A, and the other end of the second resistor R2 is grounded.

[0056] One end of the third resistor R3 is connected to the negative pole of the AC input power supply AC, and the other end of the third resistor R3 is connected to one end of the fourth resistor R4 to form a second connection point B, and the other end of the fourth resistor R4 is grounded.

[0057] It should be noted that when the sampling signal is the inductor current of the input inductor L, the first differential signal output by the differential operation module 300 is the first current differential signal I AC1 , and the second differential signal is the second current differential signal I AC2 .

[0058] When the sampling signal is the inductor current of the input inductor L, the differential operation module 300 includes:

[0059] a current conversion unit 270 configured to output a first voltage V CS and a second voltage V CS_REF respectively in response to the inductor current, and the input end of the current conversion unit 270 is connected to the other end of the input inductor L.

[0060] a third differential unit 280 configured to output a first current differential signal I CS and a second voltage V CS_REF in response to the first voltage V AC1 , and the input end of the third differential unit 280 is connected to the first output end of the current conversion unit 270.

[0061] a fourth differential unit 290 configured to output a second current differential signal I CS and a second voltage V CS_REF in response to the first voltage V AC2 , and the input end of the fourth differential unit 290 is connected to the second output end of the current conversion unit 270.

[0062] Specifically, the current conversion unit 270 includes a DC input power supply VCC, a Hall sensor U7, a fifth resistor R5, a sixth resistor R6, and a first capacitor C1. Among them,

[0063] the input end of the Hall sensor U7 is connected to the other end of the input inductor L, and the first output end of the Hall sensor U7 outputs a first voltage V CS .

[0064] One end of the fifth resistor R5 is connected to the second output end of the Hall sensor U7 and one end of the first capacitor C1, and the other end of the fifth resistor R5 is connected to one end of the sixth resistor R6 to form a third connection point C, and the third connection point outputs a second voltage V CS_REF .

[0065] The other end of the sixth resistor R6 is connected to the other end of the first capacitor C1, one end of the first capacitor C1 is connected to the DC input power supply VCC, and the other end of the first capacitor C1 is grounded.

[0066] Specifically, the third differential unit 280 is a first operational amplifier U1. The non-inverting input end of the first operational amplifier U1 is connected to the first output end of the Hall sensor U7, and the inverting input end of the first operational amplifier U1 is connected to the third connection point C.

[0067] The fourth difference unit 290 is the second operational amplifier U2. The non-inverting input terminal of the second operational amplifier U2 is connected to the third connection point C, and the inverting input terminal of the second operational amplifier U2 is connected to the first output terminal of the Hall sensor U7.

[0068] Specifically, the polarity control module 240 includes a first comparator U3 and a filter U4. Among them, the non-inverting input terminal of the first comparator U3 is connected to the first connection point A, and the inverting input terminal of the first comparator U3 is connected to the second connection point B; the output terminal of the first comparator U3 is connected to the input terminal of the filter U4.

[0069] Specifically, the signal gating module 250 is a single-pole double-throw switch K1. The control terminal of the single-pole double-throw switch K1 is connected to the output terminal of the filter U4. The first input terminal of the single-pole double-throw switch K1 is connected to the output terminal of the first operational amplifier U1, and the second input terminal of the single-pole double-throw switch K1 is connected to the output terminal of the second operational amplifier U2.

[0070] Specifically, the analog-to-digital conversion module 260 includes an analog-to-digital converter U5 and a second comparator U6. Among them, the input terminal of the analog-to-digital converter U5 is connected to the output terminal of the single-pole double-throw switch K1; the non-inverting input terminal of the second comparator U6 is connected to the output terminal of the single-pole double-throw switch K1, and the inverting input terminal of the second comparator U6 is connected to the output terminal of the reference voltage source V REF

[0071] The specific implementation principle is that after the Hall sensor U7 collects the inductor current, it outputs a first voltage V CS with a DC bias. The DC bias content of it is the second voltage V CS_REF . According to different specifications of the Hall sensor U7, the second voltage V CS_REF can be achieved by adjusting the resistance values of the voltage-dividing resistors R5 and R6. The first comparator U3 compares the voltage levels of the first voltage V CS and the second voltage V CS_REF and outputs a polarity control signal POLARITY.

[0072] The first operational amplifier U1 samples the differential voltage V CS -V CS_REF signal and outputs an I AC1 signal; the second operational amplifier U2 samples the differential voltage V CS_REF -V CS signal and outputs an I AC2 signal. After the first operational amplifier U1 and the second operational amplifier U2 output, they are connected to the single-pole double-throw switch K1, and the single-pole double-throw switch K1 is controlled by the signal of the polarity control signal POLARITY. When V CS >V CS_REF ​When the polarity control signal POLARITY is at a high level, the polarity control signal switch K1 is connected to the first operational amplifier U1, and the analog-to-digital converter U5 uses the output signal of the first operational amplifier U1; when V CS <V CS_REF When it is, POLARITY is at a low level, the polarity control signal switch is connected to the second operational amplifier U2, and the analog-to-digital converter U5 uses the output signal of the second operational amplifier U2. The waveform diagram obtained by applying the second sampling circuit described above is as shown in Figure 7 shown.

[0073] Different from the prior art, the embodiment of the present invention can realize sampling the input voltage of the totem-pole bridgeless circuit by using one ADC, reducing the chip cost of the sampling circuit and the volume of the sampling circuit, and the circuit structure is simple.

[0074] Based on the above two sampling circuits, the embodiment of the present invention provides a sampling system, the structural schematic diagram of which is as shown in Figure 8 shown. The sampling system includes a totem-pole bridgeless circuit 10 and any one of the sampling circuits 20 in the above embodiments. The totem-pole bridgeless circuit 10 includes an AC input power supply and an input inductor. The sampling circuit 20 is electrically connected to the totem-pole bridgeless circuit 10. The specific connection method has been described in the above embodiments and will not be elaborated here.

[0075] Different from the prior art, the embodiment of the present invention only needs to use one analog-to-digital converter and simple peripheral circuits, and has the advantages of low cost and small volume. In the actual circuit implementation, the analog-to-digital converter and the operational amplifier circuit can be made into one circuit implementation, and cooperate with the zero-crossing detection signal required by the totem-pole bridgeless circuit itself, which is very concise.

[0076] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. A sampling circuit is applied to a totem-pole bridgeless circuit. The totem-pole bridgeless circuit includes an AC input power supply and an input inductor. One end of the input inductor is connected to the positive pole of the AC input power supply, and it is characterized in that The sampling circuit includes: a voltage acquisition module configured to acquire and output the positive-polarity voltage and the negative-polarity voltage of the AC input power supply, the voltage acquisition module having a first sampling terminal connected to the positive pole of the AC input power supply and a second sampling terminal connected to the negative pole of the AC input power supply; a polarity control module configured to output a polarity control signal in response to the positive-polarity voltage and the negative-polarity voltage, a first input end of the polarity control module being connected to a first output end of the voltage acquisition module, and a second input end of the polarity control module being connected to a second output end of the voltage acquisition module; a differential operation module configured to output a first differential signal and a second differential signal in response to a sampling signal; a signal gating module controlled by the polarity control signal to selectively output the first differential signal or the second differential signal; the signal gating module is configured to gate the first differential signal when the polarity control signal is at a high level and to gate the second differential signal when the polarity control signal is at a low level, and an analog-to-digital conversion module configured to convert the first differential signal or the second differential signal into a corresponding digital signal, an input end of the analog-to-digital conversion module being connected to an output end of the signal gating module.

2. The circuit according to claim 1, characterized in that The voltage acquisition module includes a first resistor, a second resistor, a third resistor, and a fourth resistor, where one end of the first resistor is connected to the positive pole of the AC input power supply, the other end of the first resistor is connected to one end of the second resistor to form a first connection point, and the other end of the second resistor is grounded; one end of the third resistor is connected to the negative pole of the AC input power supply, the other end of the third resistor is connected to one end of the fourth resistor to form a second connection point, and the other end of the fourth resistor is grounded.

3. The circuit according to claim 2, characterized in that, When the sampling signal is the positive-polarity voltage and the negative-polarity voltage, the first differential signal is a first voltage differential signal, the second differential signal is a second voltage differential signal, and the differential operation module includes: a first differential unit configured to output the first voltage differential signal in response to the positive-polarity voltage and the negative-polarity voltage, an input end of the first differential unit being connected to a first output end of the voltage acquisition module; a second differential unit configured to output the second voltage differential signal in response to the positive-polarity voltage and the negative-polarity voltage, an input end of the second differential unit being connected to a second output end of the voltage acquisition module.

4. The circuit according to claim 2, wherein When the sampling signal is the inductance current of the input inductor, the first differential signal is a first current differential signal, the second differential signal is a second current differential signal, and the differential operation module includes: a current conversion unit configured to output a first voltage and a second voltage in response to the inductance current, an input end of the current conversion unit being connected to the other end of the input inductor; a third differential unit configured to output the first current differential signal in response to the first voltage and the second voltage, an input end of the third differential unit being connected to a first output end of the current conversion unit; A fourth differential unit configured to output the second current differential signal in response to the first voltage and the second voltage, wherein an input end of the fourth differential unit is connected to a second output end of the current conversion unit.

5. The circuit according to claim 3, characterized in that, The first differential unit is a first operational amplifier, a non-inverting input end of the first operational amplifier is connected to the first connection point, and an inverting input end of the first operational amplifier is connected to the second connection point; The second differential unit is a second operational amplifier, a non-inverting input end of the second operational amplifier is connected to the second connection point, and an inverting input end of the second operational amplifier is connected to the first connection point.

6. The circuit according to claim 4, wherein The current conversion unit includes a DC input power supply, a Hall sensor, a fifth resistor, a sixth resistor, and a first capacitor, wherein, An input end of the Hall sensor is connected to the other end of the input inductor, and a first output end of the Hall sensor outputs the first voltage; One end of the fifth resistor is connected to a second output end of the Hall sensor and one end of the first capacitor, and the other end of the fifth resistor is connected to one end of the sixth resistor to form a third connection point, and the third connection point outputs the second voltage; The other end of the sixth resistor is connected to the other end of the first capacitor, one end of the first capacitor is connected to the DC input power supply, and the other end of the first capacitor is grounded.

7. The circuit according to claim 6, wherein The third differential unit is a first operational amplifier, a non-inverting input end of the first operational amplifier is connected to the first output end of the Hall sensor, and an inverting input end of the first operational amplifier is connected to the third connection point; The fourth differential unit is a second operational amplifier, a non-inverting input end of the second operational amplifier is connected to the third connection point, and an inverting input end of the second operational amplifier is connected to the first output end of the Hall sensor.

8. The circuit according to claim 5 or 7, characterized in that, The polarity control module includes a first comparator and a filter, wherein, A non-inverting input end of the first comparator is connected to the first connection point, and an inverting input end of the first comparator is connected to the second connection point; An output end of the first comparator is connected to an input end of the filter.

9. The circuit according to claim 8, characterized in that, The signal gating module is a single-pole double-throw switch, a control end of the single-pole double-throw switch is connected to an output end of the filter, a first input end of the single-pole double-throw switch is connected to an output end of the first operational amplifier, and a second input end of the single-pole double-throw switch is connected to an output end of the second operational amplifier.

10. The circuit according to claim 9, wherein The analog-to-digital conversion module includes an analog-to-digital converter and a second comparator, wherein, An input end of the analog-to-digital converter is connected to an output end of the single-pole double-throw switch; A non-inverting input end of the second comparator is connected to the output end of the single-pole double-throw switch, and an inverting input end of the second comparator is connected to an output end of a reference voltage source.

11. A sampling system, characterized in that, Including: A totem-pole bridgeless circuit, the totem-pole bridgeless circuit includes an AC input power supply and an input inductor; And a sampling circuit according to any one of claims 1-10.

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