Bridgeless PFC inductive current zero-cross detection circuit, bridgeless PFC circuit and bridgeless PFC system

Abstract

The invention relates to a bridgeless PFC inductive current zero-cross detection circuit, a bridgeless PFC circuit and a bridgeless PFC system. An energy storage capacitor in the detection circuit is connected with a direct current pulsating voltage; the current-limiting voltage-stabilizing module is used for converting the direct-current pulsating voltage into a direct-current square wave signal; the voltage dividing module provides direct-current voltage bias for the direct-current square wave signal; the voltage source is connected with the voltage dividing module and the current-limiting and voltage-stabilizing module; the falling edge trigger comparator receives the direct-current square wave signal and the positive half-cycle zero-crossing comparison reference voltage, and outputs a low-level pull-down signal when the direct-current square wave signal is lower than the positive half-cycle zero-crossing comparison reference voltage; the rising edge trigger comparator receives the negative half-cycle zero-crossing comparison reference voltage and the direct-current square wave signal, and outputs a low-level pull-down signal when the direct-current square wave signal is higher than the negative half-cycle zero-crossing comparison reference voltage. According to the invention, the falling edge and the rising edge are arranged at the same time to trigger the comparator, different half-cycle zero-crossing signals are processed, and one detection circuit realizes positive and negative zero-crossing signal detection of inductive current.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a bridgeless PFC inductor current zero-crossing detection circuit and a bridgeless PFC circuit and system. Background Art

[0002] With the rapid development of society and technology, energy conservation and improved energy utilization have become urgent needs of the times. As the core device for power conversion, the power conversion efficiency of power electronic equipment has attracted much attention. With the continuous deepening of research on power factor correction (PFC) technology, new topologies such as bridgeless PFC and interleaved parallel boost PFC have emerged. Among them, boost PFC converters can be divided into continuous conduction mode (CCM), discontinuous conduction mode (DCM), and critical conduction mode (CRM), depending on whether the inductor current is continuous. Compared with CCM and DCM modes, CRM mode has the advantages of no diode reverse recovery, low switching losses, and low device stress, and performs well in improving power conversion efficiency.

[0003] When the converter operates in CRM mode, accurately detecting the inductor current zero-crossing signal is crucial for efficient control. Currently, current transformers are commonly used to detect the inductor current, or the voltage on the inductor's auxiliary winding is used to obtain the inductor current zero-crossing signal to control the conduction of the switching transistor. However, these detection methods not only increase circuit size and cost but also enhance design complexity. Furthermore, the alternating direction of the inductor current in the bridgeless PFC topology further complicates the design of the detection circuit and control scheme.

[0004] Therefore, how to simplify the current zero-crossing detection circuit design of the bridgeless PFC topology under the inductor current critical control mode and reduce the cost is an urgent problem to be solved. Summary of the Invention

[0005] In view of this, the main object of the present invention is to provide a bridgeless PFC inductor current zero-crossing detection circuit, a bridgeless PFC circuit, and a bridgeless PFC system. By simultaneously providing a set of falling-edge triggered comparators and rising-edge triggered comparators in the detection circuit, the circuit can capture the zero-crossing of the inductor current in both the positive and negative half-cycles, effectively resolving the complex circuit design issues associated with separate positive and negative inductor current detection in existing detection circuits.

[0006] In a first aspect, an embodiment of the present application provides a bridgeless PFC inductor current zero-crossing detection circuit, comprising:

[0007] An energy storage capacitor is used to connect to a DC pulsating voltage; and the fluctuation of the DC pulsating voltage can represent the current change when the inductor stores and releases energy in the critical control mode;

[0008] a current limiting and voltage stabilizing module, electrically connected to the energy storage capacitor, and configured to convert the DC pulsating voltage into a DC square wave signal;

[0009] A voltage divider module, configured to form a DC bias reference voltage to provide a DC voltage bias for the DC square wave signal;

[0010] a voltage source, electrically connected to the voltage dividing module and the current limiting and voltage stabilizing module;

[0011] A falling-edge triggered comparator, wherein the positive input terminal is used to receive the DC square wave signal, the negative input terminal is used to receive the positive half-cycle zero-crossing comparison reference voltage, and the output terminal is used to output a corresponding low-level pull-down signal when the DC square wave signal is lower than the positive half-cycle zero-crossing comparison reference voltage, so as to allow an external controller to determine whether the inductor current crosses zero in the positive half-cycle;

[0012] A rising edge triggered comparator has a positive input terminal for receiving a negative half-cycle zero-crossing comparison reference voltage, a negative input terminal for receiving the DC square wave signal, and an output terminal for outputting a corresponding low-level pull-down signal when the DC square wave signal is higher than the negative half-cycle zero-crossing comparison reference voltage, so as to allow an external controller to determine whether the inductor current crosses zero in the negative half-cycle.

[0013] In some embodiments, the current limiting and voltage stabilizing module includes a first current limiting resistor, a second current limiting resistor and a voltage stabilizing diode;

[0014] One end of the first current limiting resistor is electrically connected to the energy storage capacitor, the other end of the first current limiting resistor is respectively connected to one end of the second current limiting resistor and one end of the voltage stabilizing diode, the other end of the second current limiting resistor is electrically connected to the positive input end of the falling edge triggered comparator and the negative input end of the rising edge triggered comparator, and the other end of the voltage stabilizing diode is electrically connected to the negative pole of the voltage source.

[0015] In some embodiments, the voltage divider module includes a first voltage divider resistor and a second voltage divider resistor connected in series, the midpoint between the first voltage divider resistor and the second voltage divider resistor is electrically connected to one end of the current limiting and voltage stabilizing module, and the midpoint voltage between the first voltage divider resistor and the second voltage divider resistor forms a DC bias reference voltage to provide a DC voltage bias for the DC square wave signal.

[0016] In a second aspect, an embodiment of the present application provides a bridgeless PFC circuit, comprising: an inductor, a high-frequency rectifier circuit, an industrial frequency rectifier circuit, a filter circuit, and the bridgeless PFC inductor current zero-crossing detection circuit described in any one of the above items;

[0017] One end of the inductor is used to be electrically connected to the first output terminal of the AC power supply, and the other end of the inductor is electrically connected to the midpoint of the high-frequency rectifier circuit;

[0018] The first end of the high-frequency rectifier circuit is electrically connected to the first end of the filter circuit, and the second end of the high-frequency rectifier circuit is electrically connected to the second end of the filter circuit;

[0019] The midpoint of the power frequency rectifier circuit is used to electrically connect to the second output terminal of the AC power supply, the first end of the power frequency rectifier circuit is electrically connected to the first end of the filter circuit, and the second end of the power frequency rectifier circuit is electrically connected to the second end of the filter circuit;

[0020] A first end of the bridgeless PFC inductor current zero-crossing detection circuit is electrically connected to the midpoint of the high-frequency rectifier circuit, and a second end thereof is electrically connected to the second end of the filter circuit; and

[0021] The high-frequency rectification circuit, the power frequency rectification circuit and the bridgeless PFC inductor current zero-crossing detection circuit can all be electrically connected to an external controller.

[0022] In some embodiments, the high-frequency rectifier circuit includes a first switching tube and a second switching tube; and

[0023] The first electrode of the first switching tube is electrically connected to the first end of the filter circuit, the second electrode of the first switching tube is electrically connected to the first electrode of the second switching tube, and the control electrode of the first switching tube can be electrically connected to the first control end of the external controller;

[0024] The second pole of the second switching tube is electrically connected to the second end of the filter circuit, and the control pole of the second switching tube can be electrically connected to the second control end of the external controller; and the connection point between the first pole of the second switching tube and the second pole of the first switching tube is the midpoint of the high-frequency rectifier circuit.

[0025] In some embodiments, the power frequency rectifier circuit includes a third switch tube and a fourth switch tube; and

[0026] The first electrode of the third switch tube is electrically connected to the first end of the filter circuit, the second electrode of the third switch tube is electrically connected to the first electrode of the fourth switch tube, and the control electrode of the third switch tube is electrically connected to the third control terminal of the external controller;

[0027] The second pole of the fourth switching tube is electrically connected to the second end of the filter circuit, and the control pole of the fourth switching tube can be electrically connected to the fourth control end of the external controller; and the connection point between the first pole of the fourth switching tube and the second pole of the third switching tube is the midpoint of the industrial frequency rectifier circuit.

[0028] In some embodiments, the filtering circuit includes: a filtering capacitor and a load resistor;

[0029] The filter capacitor and the load resistor are connected in parallel, and two ends of the parallel connection correspond to the first end and the second end of the filter circuit.

[0030] In a third aspect, an embodiment of the present application provides a bridgeless PFC system, including:

[0031] The bridgeless PFC circuit according to any one of the above items;

[0032] The controller is electrically connected to the high-frequency rectification circuit, the power frequency rectification circuit and the bridgeless PFC inductor current zero-crossing detection circuit in the bridgeless PFC circuit.

[0033] Technical effects of the present invention:

[0034] The present application simultaneously sets a falling edge triggered comparator and a rising edge triggered comparator in the detection circuit to correspondingly capture the zero crossing of the inductor current in the positive half cycle and the negative half cycle. Specifically, it includes an energy storage capacitor for connecting to a DC pulsating voltage; and the fluctuation of the DC pulsating voltage can represent the current change when the inductor stores and releases energy in the critical control mode; a current limiting and voltage stabilizing module, electrically connected to the energy storage capacitor, for converting the DC pulsating voltage into a DC square wave signal; a voltage divider module, for forming a DC bias reference voltage, providing a DC voltage bias for the DC square wave signal; a voltage source, electrically connected to the voltage divider module and the current limiting and voltage stabilizing module; a falling edge triggered comparator, the positive input end receives the DC square wave signal, the negative input end receives the positive half-cycle zero-crossing comparison reference voltage, and the output end outputs a corresponding low-level pull-down signal when the DC square wave signal is lower than the positive half-cycle zero-crossing comparison reference voltage, so that the external controller can determine that the inductor current crosses zero in the positive half-cycle; a rising edge triggered comparator, the positive input end receives the negative half-cycle zero-crossing comparison reference voltage, the negative input end receives the DC square wave signal, and the output end outputs a corresponding low-level pull-down signal when the DC square wave signal is higher than the negative half-cycle zero-crossing comparison reference voltage, so that the external controller can determine that the inductor current crosses zero in the negative half-cycle. Therefore, it can be seen that the present application simultaneously sets a falling-edge triggered comparator and a rising-edge triggered comparator to process the zero-crossing signals of different half-cycles respectively. Regardless of how the direction of the current changes, the zero-crossing event can be detected by the corresponding comparator. Compared with the existing detection circuit design, which is complex and requires two independent detection circuits to detect the positive and negative directions of the inductor current separately, the present application uses a single detection circuit to detect zero-crossing signals in both the positive and negative directions of the inductor current, while also ensuring timely switching in the critical mode to maintain the critical continuity of the inductor current.

[0035] Further features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0037] Figure 1 FIG2 is a circuit diagram of a bridgeless PFC inductor current zero-crossing detection circuit according to an embodiment of the present application;

[0038] Figure 2 FIG. 1 is a circuit diagram of a bridgeless PFC circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0039] Various exemplary embodiments, features, and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0040] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0041] In addition, numerous specific details are provided in the following detailed description to better illustrate the present disclosure. Those skilled in the art will appreciate that the present disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art are not described in detail in order to highlight the main points of the present disclosure.

[0042] like Figure 1 As shown, in a first aspect, an embodiment of the present application provides a bridgeless PFC inductor current zero-crossing detection circuit, comprising:

[0043] The energy storage capacitor C2 is used to connect to the DC pulsating voltage; the fluctuation of the DC pulsating voltage can represent the current change when the inductor stores and releases energy in the critical control mode;

[0044] The current limiting and voltage stabilizing module 10 is electrically connected to the energy storage capacitor C2 and is used to convert the DC pulsating voltage into a DC square wave signal;

[0045] A voltage divider module is used to form a DC bias reference voltage to provide a DC voltage bias for the DC square wave signal;

[0046] A voltage source electrically connected to the voltage divider module and the current limiting and voltage stabilizing module 10;

[0047] The falling edge triggered comparator 20 has a positive input terminal for receiving a DC square wave signal, a negative input terminal for receiving a positive half cycle zero-crossing comparison reference voltage, and an output terminal for outputting a corresponding low-level pull-down signal when the DC square wave signal is lower than the positive half cycle zero-crossing comparison reference voltage, so as to allow an external controller to determine whether the inductor current crosses zero in the positive half cycle;

[0048] The rising edge triggered comparator 30 has a positive input terminal for receiving a negative half-cycle zero-crossing comparison reference voltage, a negative input terminal for receiving a DC square wave signal, and an output terminal for outputting a corresponding low-level pull-down signal when the DC square wave signal is higher than the negative half-cycle zero-crossing comparison reference voltage, so as to allow an external controller to determine whether the inductor current crosses zero in the negative half-cycle.

[0049] To address the complex circuit design issues associated with current zero-crossing detection circuits in existing bridgeless PFC topologies operating in the inductor current critical control mode, this embodiment provides both a falling-edge triggered comparator 20 and a rising-edge triggered comparator 30 in the detection circuit to capture the zero-crossings of the inductor current in both the positive and negative half-cycles.

[0050] Specifically, the detection circuit of this embodiment includes an energy storage capacitor C2, a current limiting and voltage stabilizing module 10, a voltage divider module, a voltage source, a falling edge trigger comparator 20 and a rising edge trigger comparator 30, wherein the first end of the energy storage capacitor C2 is connected to a node capable of outputting a DC pulsating voltage, and the voltage conversion stores energy in the energy storage capacitor C2, that is, it is used to store the electric field energy corresponding to the DC pulsating voltage, and the fluctuation of the DC pulsating voltage can represent in real time the current changes corresponding to the inductor energy storage (charging) and energy release (discharging) process under the critical control mode, and use this as the basis for capturing the zero crossing of the inductor current in the positive and negative half cycles. At the same time, as the DC pulsating voltage changes, the energy storage capacitor C2 will charge or discharge accordingly, and transmit the edge changes of the pulsating voltage to the back-end circuit through the charging and discharging behavior. Here, it should be noted that the DC pulsating voltage of this embodiment is the result of high-frequency rectification of the input AC power supply.

[0051] Furthermore, in this embodiment, the first end of the current limiting and voltage stabilizing module 10 is electrically connected to the second end of the energy storage capacitor C2, converting the higher DC pulsating voltage into a low-voltage DC square wave signal. The second end of the current limiting and voltage stabilizing module 10 is electrically connected to the positive input end of the falling edge trigger comparator 20 and the negative input end of the rising edge trigger comparator 30, and the rising edge and falling edge of the DC square wave signal will correspondingly cause the level changes of the positive input end of the falling edge trigger comparator 20 and the negative input end of the rising edge trigger comparator 30. In addition, the voltage divider module of this embodiment can form a DC bias reference voltage to provide a DC bias for the DC square wave signal, and the voltage source provides a stable reference voltage for the voltage divider module, wherein the voltage source is a DC voltage source, and the positive half-cycle zero-crossing comparison reference voltage and the negative half-cycle zero-crossing comparison reference voltage can be specifically configured according to actual needs. It should be noted that the positive half-cycle zero-crossing comparison reference voltage is connected to the negative input of the falling-edge-triggered comparator 20, and the negative half-cycle zero-crossing comparison reference voltage is connected to the positive input of the rising-edge-triggered comparator 30. When the comparator is not in operation, the output is always high. It should be noted that when the DC square wave signal has a falling edge, the voltage at the positive input of the falling-edge-triggered comparator 20 is lower than the positive half-cycle zero-crossing comparison reference voltage at the negative input, triggering the output of the falling-edge-triggered comparator 20 to generate a corresponding low-level pull-down signal, which the external controller uses to determine whether the inductor current has crossed zero in the positive half-cycle and control the switching of the corresponding switch. Similarly, when the DC square wave signal has a rising edge, the voltage at the negative input of the rising-edge-triggered comparator 30 is higher than the negative half-cycle zero-crossing comparison reference voltage at the positive input, triggering the output of the rising-edge-triggered comparator 30 to generate a corresponding low-level pull-down signal, which the external controller uses to determine whether the inductor current has crossed zero in the negative half-cycle and control the switching of the corresponding switch.

[0052] As can be seen, the detection circuit of this embodiment converts the pulsating DC voltage into a DC square wave signal, uses a voltage divider module to set an appropriate bias reference voltage, and uses a falling-edge-triggered comparator 20 and a rising-edge-triggered comparator 30 to detect voltage edge changes corresponding to the positive and negative half-cycles, respectively, thereby triggering controller action. Specifically, by simultaneously providing a falling-edge-triggered comparator 20 and a rising-edge-triggered comparator 30 to process zero-crossing signals from different half-cycles, the corresponding comparator can detect zero-crossing events regardless of the direction of the current. Compared to existing detection circuits, which are complex in design and require two independent detection circuits to detect the positive and negative inductor currents separately, this embodiment eliminates the need for two independent detection circuits. Instead, a single detection circuit can detect zero-crossing signals in both the positive and negative directions of the inductor current, while also ensuring timely switching in critical mode and maintaining critical continuity of the inductor current.

[0053] In some embodiments, the current limiting and voltage stabilizing module 10 includes a first current limiting resistor R2, a second current limiting resistor R5 and a voltage stabilizing diode Z1;

[0054] One end of the first current limiting resistor R2 is electrically connected to the energy storage capacitor C2, the other end of the first current limiting resistor R2 is respectively connected to one end of the second current limiting resistor R5 and one end of the voltage zener diode Z1, the other end of the second current limiting resistor R5 is electrically connected to the positive input end of the falling edge triggered comparator 20 and the negative input end of the rising edge triggered comparator 30, and the other end of the voltage zener diode Z1 is electrically connected to the negative pole of the voltage source.

[0055] In this embodiment, a high DC pulsating voltage is converted into a low-voltage DC square wave signal via a current-limiting resistor and a Zener diode Z1. Specifically, the circuit includes a first current-limiting resistor R2, a second current-limiting resistor R5, and a Zener diode Z1. The first end of the first current-limiting resistor R2 is electrically connected to the second end of the energy storage capacitor C2, the second end of the first current-limiting resistor R2 is electrically connected to the first end of the second current-limiting resistor R5 and the cathode of the Zener diode Z1, the second end of the second current-limiting resistor R5 is electrically connected to the positive input of the falling-edge-triggered comparator 20 and the negative input of the rising-edge-triggered comparator 30, and the anode of the Zener diode Z1 is electrically connected to the negative electrode of the DC power supply. In other words, by providing the current-limiting resistor and the Zener diode Z1, the detection circuit is protected from excessive voltage while converting the DC pulsating voltage into a low-voltage signal suitable for comparator operation, thereby enabling the comparator to detect the zero-crossing of the inductor current.

[0056] In some embodiments, the voltage divider module includes a first voltage divider resistor R6 and a second voltage divider resistor R4 connected in series, the midpoint between the first voltage divider resistor R6 and the second voltage divider resistor R4 is electrically connected to one end of the current limiting and voltage stabilizing module 10, and the midpoint voltage between the first voltage divider resistor R6 and the second voltage divider resistor R4 forms a DC bias reference voltage to provide a DC voltage bias for the DC square wave signal.

[0057] In this embodiment, the midpoint voltage of the voltage divider module is used as a DC voltage bias. Specifically, one end of the first voltage divider resistor R6 and one end of the second voltage divider resistor R4 in the voltage divider module are electrically connected, that is, the midpoint voltage of the first voltage divider resistor R6 and the second voltage divider resistor R4 forms a DC bias reference voltage VREF1, which can provide a DC voltage bias for the DC square wave signal, ensuring that the signal fluctuates at an appropriate DC level and avoids exceeding the common mode range of the comparator, thereby enabling the comparator to accurately identify the rising edge and the falling edge, ensuring the implementation of zero-crossing detection. Among them, the two ends of the voltage divider module are correspondingly connected to the positive and negative poles of the DC voltage source, providing a stable reference voltage for the voltage divider module, thereby providing a basis for the judgment of the comparator.

[0058] It should be noted that in this embodiment, the intermediate node between the first voltage-dividing resistor R6 and the second voltage-dividing resistor R4 serves as the detection midpoint. Specifically, the second end of the second current-limiting resistor R5 is electrically connected to the intermediate node between the first voltage-dividing resistor R6 and the second voltage-dividing resistor R4, and this intermediate node is also electrically connected to the positive input of the falling-edge-triggered comparator 20 and the negative input of the rising-edge-triggered comparator 30. When a falling edge occurs at the detection midpoint, the voltage at the positive input of the falling-edge-triggered comparator 20 is lower than the positive half-cycle zero-crossing comparison reference voltage VREF2 of the negative input, and the output of the falling-edge-triggered comparator 20 generates a low-level pull-down signal. When a rising edge occurs at the detection midpoint, the voltage at the negative input of the rising-edge-triggered comparator 30 is higher than the negative half-cycle zero-crossing comparison reference voltage VREF3 of the positive input, and the output of the rising-edge-triggered comparator 30 generates a low-level pull-down signal.

[0059] As can be seen from this, the bridgeless PFC inductor current zero-crossing detection circuit of the present application stores the energy corresponding to the DC pulsating voltage that can represent the inductor current state in the critical control mode in the energy storage capacitor C2, and converts the DC pulsating voltage into a DC square wave signal through the current limiting resistor and the voltage stabilizing diode Z1. When the rising and falling edges of the DC square wave signal cause the corresponding comparator input voltage to change, the output voltage is triggered by comparing with the reference level of the other input terminal of the comparator, so that the external controller can control the corresponding switch tube to turn on and off. The detection circuit of the present application can jointly detect the zero-crossing signals of the inductor current in both the positive and negative directions, optimizing the existing two detection circuits for separate detection of the inductor current in the positive and negative directions, simplifying the circuit design while reducing production and maintenance costs.

[0060] like Figure 2 As shown, in a second aspect, an embodiment of the present application provides a bridgeless PFC circuit, comprising: an inductor L1, a high-frequency rectifier circuit 101, an industrial frequency rectifier circuit 102, a filter circuit 103, and any one of the above bridgeless PFC inductor current zero-crossing detection circuits 104;

[0061] One end of the inductor is used to be electrically connected to the first output terminal of the AC power supply, and the other end of the inductor is electrically connected to the midpoint of the high-frequency rectifier circuit 101;

[0062] A first end of the high-frequency rectifier circuit 101 is electrically connected to a first end of the filter circuit 103 , and a second end of the high-frequency rectifier circuit 101 is electrically connected to a second end of the filter circuit 103 ;

[0063] The midpoint of the power frequency rectifier circuit 102 is electrically connected to the second output terminal of the AC power supply, the first terminal of the power frequency rectifier circuit 102 is electrically connected to the first terminal of the filter circuit 103, and the second terminal of the power frequency rectifier circuit 102 is electrically connected to the second terminal of the filter circuit 103;

[0064] A first terminal of the bridgeless PFC inductor current zero-crossing detection circuit 104 is electrically connected to the midpoint of the high-frequency rectification circuit 101 , and a second terminal thereof is electrically connected to the second terminal of the filter circuit 103 ; and

[0065] The high-frequency rectification circuit 101 , the power-frequency rectification circuit 102 and the bridgeless PFC inductor current zero-crossing detection circuit 104 can all be electrically connected to an external controller.

[0066] In this embodiment, a bridgeless PFC circuit with a detection circuit 104 is provided. Specifically, the circuit includes an inductor, a high-frequency rectifier circuit 101, a power-frequency rectifier circuit 102, a filter circuit 103, and any of the aforementioned detection circuits 104. Inductor L1 is a boost inductor, with a first end connected to the AC input and a second end connected to the midpoint of the high-frequency rectifier circuit 101. The control end of the high-frequency rectification circuit can be connected to an external controller 105, and the upper and lower nodes of the high-frequency rectifier circuit 101 are respectively connected to the upper and lower nodes of the filter circuit 103. Furthermore, in this embodiment, the detection circuit 104 has a first end connected to the midpoint of the high-frequency rectifier circuit 101, a second end connected to the lower node of the filter circuit 103 (i.e., the end to which the anode of the Zener diode Z1 in the detection circuit 104 is connected), and two nodes of the third end are respectively connected to the external controller 105. Furthermore, the midpoint of the power-frequency rectifier circuit 102 is connected to the other end of the AC input, and the upper and lower nodes of the power-frequency rectifier circuit 102 are respectively connected to the upper and lower nodes of the filter circuit 103.

[0067] Specifically, the inductor of this embodiment boosts the AC input voltage to obtain an AC voltage, and the boosted AC voltage is processed into a pulsating DC voltage through the high-frequency rectifier circuit 101 and the power-frequency rectifier circuit 102. It should be noted that the high-frequency rectifier circuit 101 and the power-frequency rectifier circuit 102 of this embodiment implement critical continuous mode control of the inductor current through any of the above-mentioned detection circuits 104 and the external controller 105, and the pulsating DC voltage is processed by the filter circuit 103 to obtain a stable DC voltage. That is, the midpoint output of the high-frequency rectifier circuit 101 is a DC pulsating voltage, and the midpoint of the high-frequency rectifier circuit 101 is electrically connected to the first end of the energy storage capacitor C2 in the detection circuit 104. The voltage conversion stores energy in the energy storage capacitor C2 for subsequent circuits to perform zero-crossing detection of the inductor current. Furthermore, the totem pole bridgeless PFC circuit of this embodiment simplifies the current detection circuit 104 of the bridgeless PFC topology in the inductor current critical control mode. Both the positive and negative inductor currents can be detected through a single detection circuit 104, thereby simplifying the entire circuit design and saving production costs.

[0068] In some embodiments, the high-frequency rectifier circuit 101 includes a first switch tube Q1 and a second switch tube Q2; and

[0069] A first electrode of the first switch tube Q1 is electrically connected to a first terminal of the filter circuit 103 , a second electrode of the first switch tube Q1 is electrically connected to a first electrode of the second switch tube Q2 , and a control electrode of the first switch tube Q1 can be electrically connected to a first control terminal of the external controller 105 ;

[0070] The second pole of the second switch tube Q2 is electrically connected to the second end of the filter circuit 103, and the control pole of the second switch tube Q2 can be electrically connected to the second control end of the external controller 105; and the connection point between the first pole of the second switch tube Q2 and the second pole of the first switch tube Q1 is the midpoint of the high-frequency rectifier circuit 101.

[0071] In this embodiment, both the first switching transistor Q1 and the second switching transistor Q2 are high-frequency transistors, and the node connecting the first switching transistor Q1 and the second switching transistor Q2 is the midpoint of the high-frequency rectifier circuit 101. The second end of the inductor is connected to the midpoint of the high-frequency rectifier circuit 101, thereby converting the self-inductance AC output of the inductor into DC power through the high-frequency rectifier circuit 101. It should be noted that the control terminals of the first switching transistor Q1 and the second switching transistor Q2 in this embodiment are respectively connected to corresponding control terminals of the external controller 105, so that the first switching transistor Q1 and the second switching transistor Q2 can be controlled to turn on and off according to the control signal of the controller, thereby completing the energy storage and release of the inductor.

[0072] In some embodiments, the power frequency rectifier circuit 102 includes a third switch tube Q3 and a fourth switch tube Q4; and

[0073] A first terminal of the third switch tube Q3 is electrically connected to a first terminal of the filter circuit 103, a second terminal of the third switch tube Q3 is electrically connected to a first terminal of the fourth switch tube Q4, and a control terminal of the third switch tube Q3 is electrically connected to a third control terminal of the external controller 105;

[0074] The second electrode of the fourth switch tube Q4 is electrically connected to the second end of the filter circuit 103, and the control electrode of the fourth switch tube Q4 can be electrically connected to the fourth control end of the external controller 105; and the connection point between the first electrode of the fourth switch tube Q4 and the second electrode of the third switch tube Q3 is the midpoint of the power frequency rectifier circuit 102.

[0075] In this embodiment, the third and fourth switching transistors Q3 and Q4 are both power-frequency transistors, and the node connected to the third and fourth switching transistors Q3 and Q4 is the midpoint of the power-frequency rectifier circuit 102. One end of the AC power source is connected to the boost inductor, and the other end is connected to the midpoint of the power-frequency rectifier circuit 102. The power-frequency rectifier circuit 102 maintains the current direction of the DC power output by the totem-pole bridgeless PFC circuit. Therefore, in this embodiment, the AC power source AC and the inductor L1 are connected between the midpoints of the high-frequency rectifier circuit 101 and the power-frequency rectifier circuit 102. That is, the high-frequency rectifier circuit 101 and the power-frequency rectifier circuit 102 form a rectifier module that converts the boosted AC voltage into a pulsating DC voltage. It should be noted that the control terminals of the third and fourth switching transistors Q3 and Q4 can also be connected to corresponding control terminals of an external controller and turned on and off by control signals.

[0076] In some embodiments, the filter circuit 103 includes: a filter capacitor C1 and a load resistor R1;

[0077] The filter capacitor C1 and the load resistor R1 are connected in parallel, and two ends of the parallel connection correspond to a first end and a second end of the filter circuit 103 .

[0078] The filter circuit 103 of this embodiment uses a filter capacitor C1 and a load resistor R1 in parallel, so as to process the pulsating DC voltage and obtain a stable DC voltage.

[0079] The on and off control of the above-mentioned switch tube will be described in detail below.

[0080] During the positive half cycle of the AC input voltage, the first switch tube Q1 and the second switch tube Q2 are turned on and off under the control of the control signal, completing the energy storage and release of the inductor. The fourth switch tube Q4 is continuously turned on under the control of the control signal, forming an energy closed loop back to the AC input.

[0081] Specifically, during the positive half cycle of the AC input voltage, when the inductor is in the energy storage stage, the first switch tube Q1 is turned off, the second switch tube Q2 is turned on, and the fourth switch tube Q4 is turned on. At this time, the inductor current direction is inductor-second switch tube Q2-fourth switch tube Q4-inductor; when the inductor is in the release stage, the first switch tube Q1 is turned on, the second switch tube Q2 is turned off, and the fourth switch tube Q4 is turned on. At this time, the inductor current direction is inductor-first switch tube Q1-filter capacitor C1-fourth switch tube Q4-inductor; during zero-crossing detection, the first switch tube Q1 is turned on, the second switch tube Q2 is turned off, and the fourth switch tube Q4 is turned on.

[0082] When the AC input voltage is in the negative half cycle, the first switch tube Q1 and the second switch tube Q2 are turned on and off under the control of the control signal, completing the energy storage and release of the inductor. The third switch tube Q3 is continuously turned on under the control of the control signal, forming an energy closed loop to return to the AC input.

[0083] Specifically, during the negative half-cycle of the AC input voltage: when the inductor is in the energy storage stage, the first switch tube Q1 is turned on, the second switch tube Q2 is turned off, and the third switch tube Q3 is turned on. At this time, the inductor current direction is inductor-first switch tube Q1-third switch tube Q3-inductor; when the inductor is in the release stage, the first switch tube Q1 is turned off, the second switch tube Q2 is turned on, and the third switch tube Q3 is turned on. At this time, the inductor current direction is inductor-second switch tube Q2-third switch tube Q3-inductor; during zero-crossing detection, the first switch tube Q1 is turned off, the second switch tube Q2 is turned on, and the third switch tube Q3 is turned on.

[0084] As can be seen, in the bridgeless PFC circuit of this embodiment, the detection circuit 104 detects the zero-crossing signal of the inductor current, i.e., the corresponding comparator output terminal generates a low-level pull-down signal that is transmitted to the corresponding port of the external controller. The external controller then utilizes the connection relationship between the external controller and the corresponding switch tube to send a control signal to the external controller to control the on and off of the switch tube. When the zero-crossing signal is detected, the corresponding switch tube can be immediately turned off to prevent the inductor current from flowing in reverse, thereby achieving lower EMI in the interleaved parallel totem pole bridgeless PFC circuit.

[0085] In a third aspect, an embodiment of the present application provides a bridgeless PFC system, including:

[0086] A bridgeless PFC circuit according to any of the above;

[0087] The controller 105 is electrically connected to the high-frequency rectification circuit 101 , the power frequency rectification circuit 102 and the bridgeless PFC inductor current zero-crossing detection circuit 104 in the bridgeless PFC circuit.

[0088] The controller 105 of this embodiment is configured to be electrically connected to any of the aforementioned bridgeless PFC circuits, thereby controlling the on / off switching of each switch in the circuit by sending control signals to the bridgeless PFC circuit. Specifically, a first control terminal S1 of the controller is connected to the control electrode of the first switch Q1, a second control terminal S2 of the controller is connected to the control electrode of the second switch Q2, a third control terminal S3 of the controller is connected to the control electrode of the third switch Q3, and a fourth control terminal S4 of the controller is connected to the control electrode of the fourth switch Q4. Furthermore, a fifth control terminal D1 of the controller is connected to the output of a rising-edge-triggered comparator 30, and a sixth control terminal D2 of the controller is connected to the output of a falling-edge-triggered comparator 20. When the output of the falling-edge-triggered comparator 20 or the rising-edge-triggered comparator 30 generates a low-level pull-down signal, i.e., when the inductor current returns to zero, the low-level pull-down signal is transmitted to the corresponding controller control terminal, enabling the controller to control the corresponding switch on and off when the inductor current crosses zero, thereby meeting the timing requirements of the CRM mode.

[0089] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0090] Unless otherwise defined, the technical terms or scientific terms involved in this application should have the usual meanings understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "the" and similar words involved in this application do not indicate quantity restrictions and can indicate the singular or plural. The terms "include", "comprise", "have" and any variations thereof involved in this application are intended to cover non-exclusive inclusions. The words "connect", "connected", "coupled" and similar words involved in this application are not limited to physical or mechanical connections, but include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more, and "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. The terms "first", "second", "third" and the like involved in this application are merely to distinguish similar objects and do not represent a specific ordering of objects.

[0091] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make several modifications or improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A bridgeless PFC inductor current zero-crossing detection circuit, characterized in that: include: An energy storage capacitor is used to connect to a DC pulsating voltage; and the fluctuation of the DC pulsating voltage can represent the current change when the inductor stores and releases energy in the critical control mode; a current limiting and voltage stabilizing module, electrically connected to the energy storage capacitor, and configured to convert the DC pulsating voltage into a DC square wave signal; A voltage divider module, configured to form a DC bias reference voltage to provide a DC voltage bias for the DC square wave signal; a voltage source, electrically connected to the voltage dividing module and the current limiting and voltage stabilizing module; A falling-edge triggered comparator, wherein the positive input terminal is used to receive the DC square wave signal, the negative input terminal is used to receive the positive half-cycle zero-crossing comparison reference voltage, and the output terminal is used to output a corresponding low-level pull-down signal when the DC square wave signal is lower than the positive half-cycle zero-crossing comparison reference voltage, so as to allow an external controller to determine whether the inductor current crosses zero in the positive half-cycle; A rising edge triggered comparator has a positive input terminal for receiving a negative half-cycle zero-crossing comparison reference voltage, a negative input terminal for receiving the DC square wave signal, and an output terminal for outputting a corresponding low-level pull-down signal when the DC square wave signal is higher than the negative half-cycle zero-crossing comparison reference voltage, so as to allow an external controller to determine whether the inductor current crosses zero in the negative half-cycle.

2. The bridgeless PFC inductor current zero-crossing detection circuit according to claim 1, characterized in that: The current limiting and voltage stabilizing module includes a first current limiting resistor, a second current limiting resistor and a voltage stabilizing diode; One end of the first current limiting resistor is electrically connected to the energy storage capacitor, the other end of the first current limiting resistor is respectively connected to one end of the second current limiting resistor and one end of the voltage stabilizing diode, the other end of the second current limiting resistor is electrically connected to the positive input end of the falling edge triggered comparator and the negative input end of the rising edge triggered comparator, and the other end of the voltage stabilizing diode is electrically connected to the negative pole of the voltage source.

3. The bridgeless PFC inductor current zero-crossing detection circuit according to claim 1, characterized in that: The voltage divider module includes a first voltage divider resistor and a second voltage divider resistor connected in series, the midpoint between the first voltage divider resistor and the second voltage divider resistor is electrically connected to one end of the current limiting and voltage stabilizing module, and the midpoint voltage between the first voltage divider resistor and the second voltage divider resistor forms a DC bias reference voltage, providing a DC voltage bias for the DC square wave signal.

4. A bridgeless PFC circuit, characterized in that: include: An inductor, a high-frequency rectifier circuit, an industrial frequency rectifier circuit, a filter circuit, and a bridgeless PFC inductor current zero-crossing detection circuit according to any one of claims 1 to 3; One end of the inductor is used to be electrically connected to the first output terminal of the AC power supply, and the other end of the inductor is electrically connected to the midpoint of the high-frequency rectifier circuit; The first end of the high-frequency rectifier circuit is electrically connected to the first end of the filter circuit, and the second end of the high-frequency rectifier circuit is electrically connected to the second end of the filter circuit; The midpoint of the power frequency rectifier circuit is used to electrically connect to the second output terminal of the AC power supply, the first end of the power frequency rectifier circuit is electrically connected to the first end of the filter circuit, and the second end of the power frequency rectifier circuit is electrically connected to the second end of the filter circuit; A first end of the bridgeless PFC inductor current zero-crossing detection circuit is electrically connected to the midpoint of the high-frequency rectifier circuit, and a second end thereof is electrically connected to the second end of the filter circuit; and The high-frequency rectification circuit, the power frequency rectification circuit and the bridgeless PFC inductor current zero-crossing detection circuit can all be electrically connected to an external controller.

5. The bridgeless PFC circuit according to claim 4, wherein: The high-frequency rectifier circuit includes a first switching tube and a second switching tube; and The first electrode of the first switching tube is electrically connected to the first end of the filter circuit, the second electrode of the first switching tube is electrically connected to the first electrode of the second switching tube, and the control electrode of the first switching tube can be electrically connected to the first control end of the external controller; The second pole of the second switching tube is electrically connected to the second end of the filter circuit, and the control pole of the second switching tube can be electrically connected to the second control end of the external controller; and the connection point between the first pole of the second switching tube and the second pole of the first switching tube is the midpoint of the high-frequency rectifier circuit.

6. The bridgeless PFC circuit according to claim 4, wherein: The power frequency rectifier circuit includes a third switch tube and a fourth switch tube; and The first electrode of the third switch tube is electrically connected to the first end of the filter circuit, the second electrode of the third switch tube is electrically connected to the first electrode of the fourth switch tube, and the control electrode of the third switch tube is electrically connected to the third control terminal of the external controller; The second pole of the fourth switching tube is electrically connected to the second end of the filter circuit, and the control pole of the fourth switching tube can be electrically connected to the fourth control end of the external controller; and the connection point between the first pole of the fourth switching tube and the second pole of the third switching tube is the midpoint of the industrial frequency rectifier circuit.

7. The bridgeless PFC circuit according to claim 4, wherein: The filtering circuit includes: a filtering capacitor and a load resistor; The filter capacitor and the load resistor are connected in parallel, and two ends of the parallel connection correspond to the first end and the second end of the filter circuit.

8. A bridgeless PFC system, characterized in that: include: The bridgeless PFC circuit according to any one of claims 4 to 7; The controller is electrically connected to the high-frequency rectification circuit, the power frequency rectification circuit and the bridgeless PFC inductor current zero-crossing detection circuit in the bridgeless PFC circuit.

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