Power factor correction circuit and equipment thereof

Abstract

The embodiment of the invention discloses a power factor correction circuit and equipment thereof, and the circuit comprises a bias voltage module which is configured to be used for generating a preset bias voltage, and generating a positive half-cycle reference voltage and a negative half-cycle reference voltage based on the preset bias voltage; the operation module is configured to be used for receiving the alternating-current voltage signal and outputting a difference signal according to the alternating-current voltage signal and a preset bias voltage; and the comparison module is configured to compare the difference signal with the positive half-cycle reference voltage and the negative half-cycle reference voltage respectively and generate an indication signal indicating the polarity and the amplitude of the AC voltage signal. According to the embodiment of the invention, the detection of the polarity and amplitude of the AC voltage signal is realized by comparing the difference signal with the selected positive and negative half-cycle reference voltages, the use of a negative voltage comparator is avoided, the circuit structure is simplified, the cost is reduced, and the detection precision and reliability are improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of power factor correction, and in particular to a power factor correction circuit and a device thereof. Background Art

[0002] As the world pays more and more attention to the sustainable use of energy, countries have also continuously improved their requirements for energy efficiency and environmental protection. Many countries and regions have formulated strict power factor regulations and standards, and the power factor correction (PFC) circuit has become one of the necessary measures to comply with these regulations and standards. In an ideal power environment, the power factor requirement is as close to 1 as possible, because it means that the input electrical energy is almost completely effectively utilized and converted into the energy required for work, without generating invalid power loss.

[0003] However, in actual applications, the phase difference between current and voltage leads to the generation of invalid power, which is what we usually call "reactive power". Reactive power not only causes energy waste and increases electricity costs, but also creates an additional burden on the power grid. In order to improve this situation, the PFC circuit came into being. The main function of the PFC circuit is to adjust the phase difference between current and voltage to make them as synchronized as possible, thereby improving the power factor of the switching power supply system, reducing the generation of invalid power, reducing energy waste, and reducing the burden on the power grid, thereby achieving the concept of sustainable development.

[0004] In the PFC circuit, it is essential to detect the polarity and amplitude of the input voltage Vac, so as to determine the state of the circuit or take corresponding protection measures. Since the input voltage Vac is a symmetrical sine wave signal with positive and negative half cycles, a traditional solution is to directly use an operation circuit to obtain acl-acn, so negative voltage will appear and a negative voltage comparator is needed; another solution is to first use a comparator to distinguish the positive and negative half cycles, and then use two operation circuits to obtain the voltage difference acl-acn or acn-acl. The traditional solution requires the use of a negative voltage comparator or two operation circuits, which inevitably need to distinguish the positive and negative half cycles of the input voltage Vac, and the structure is relatively complex and the cost is high. Summary of the invention

[0005] The main technical problem solved by the embodiments of the present invention is to provide a power factor correction circuit and a device thereof, which can solve some problems existing in the existing power factor correction circuit.

[0006] In order to solve the above technical problems, a technical solution adopted in an embodiment of the present invention is: to provide a power factor correction circuit, including: a bias voltage module, configured to generate a preset bias voltage, and generate a positive half-cycle reference voltage and a negative half-cycle reference voltage based on the preset bias voltage; an operation module, configured to receive an AC voltage signal, and output a difference signal according to the AC voltage signal and the preset bias voltage; a comparison module, configured to compare the difference signal with the positive half-cycle reference voltage and the negative half-cycle reference voltage, respectively, to generate an indication signal indicating the polarity and amplitude of the AC voltage signal.

[0007] In some embodiments, the bias voltage module includes a voltage generating unit and a voltage output unit, the voltage generating unit is configured to generate the preset bias voltage according to a reference voltage provided by a reference voltage source; the voltage output unit is configured to generate the positive half-cycle reference voltage and the negative half-cycle reference voltage according to the preset bias voltage.

[0008] In some embodiments, the voltage generating unit includes an operational amplifier AMP2, a transistor M1, a resistor R6 and a resistor R7, the inverting input terminal of the operational amplifier AMP2 is connected to the reference voltage source, the non-inverting input terminal of the operational amplifier AMP2 is connected to the second end of the resistor R6 and the first end of the resistor R7, the output terminal of the operational amplifier AMP2 is connected to the gate of the transistor M1, the drain of the transistor M1 is connected to the first end of the resistor R6 and the input terminal of the voltage output unit, and the source of the transistor M1 is connected to a power supply.

[0009] In some embodiments, the voltage output unit includes n voltage-dividing resistors connected in series, n≥3, and the connection points of adjacent voltage-dividing resistors constitute voltage-dividing points; wherein, the voltage Vk of the kth voltage-dividing point satisfies: Vk=VOS×(nk) / n, wherein the value range of k is 1 to n-1, and VOS is the preset bias voltage.

[0010] In some embodiments, the operation module includes: an operational amplifier AMP1, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a resistor R5, the first end of the resistor R1 is connected to the first end of the AC voltage signal source, the second end of the resistor R1 is connected to the first end of the resistor R5 and the inverting input end of the operational amplifier AMP1, the first end of the resistor R2 is connected to the second end of the AC voltage signal source, and the second end of the resistor R2 is connected to the non-inverting input end of the operational amplifier AMP1; the first end of the resistor R3 is connected to the bias voltage output end of the bias voltage module, the second end of the resistor R3 is connected to the first end of the resistor R4 and the non-inverting input end of the operational amplifier AMP1, and the output end of the operational amplifier AMP1 is connected to the second end of the resistor R5 and the positive input end of the comparison module.

[0011] In some embodiments, the resistance values ​​of the resistor R1 , the resistor R2 and the resistor R3 are equal, and the resistor R1 , the resistor R4 and the resistor R5 satisfy: R5 / R4=(R1+R5) / (R1+2R4).

[0012] In some embodiments, the positive half-cycle reference voltage is any voltage at a voltage division point greater than a first preset value, and the negative half-cycle reference voltage is any voltage at a voltage division point less than the first preset value; the first preset value is calculated according to the following formula: V middle =R5 / R1×VOS.

[0013] In some embodiments, the comparison module includes a comparator COMP1 and a comparator COMP2, the non-inverting input terminal of the comparator COMP1 is connected to the inverting input terminal of the comparator COMP2 and the output terminal of the operation module, the inverting input terminal of the comparator COMP1 is connected to the positive half-cycle output terminal of the bias voltage module, and the non-inverting input terminal of the comparator COMP2 is connected to the negative half-cycle output terminal of the bias voltage module.

[0014] In some embodiments, when the AC voltage signal is in a positive half-cycle, the comparator COMP1 compares the difference signal with the positive half-cycle reference voltage, and outputs a first amplitude indication signal when the difference signal exceeds the positive half-cycle reference voltage; when the AC voltage signal is in a negative half-cycle, the comparator COMP2 compares the difference signal with the negative half-cycle reference voltage, and outputs a second amplitude indication signal when the difference signal is lower than the negative half-cycle reference voltage.

[0015] In order to solve the above technical problem, another technical solution adopted by the embodiment of the present invention is: to provide a power factor correction device, including: the power factor correction circuit as described above.

[0016] The beneficial effects of the embodiments of the present invention are as follows: different from the prior art, the embodiments of the present invention realize the detection of the polarity and amplitude of the AC voltage signal by adopting a method of comparing the difference signal with the positive and negative half-cycle reference voltages selected respectively, avoiding the addition of an additional comparator to distinguish the positive and negative half-cycles of the input voltage, simplifying the circuit structure, reducing costs, and improving detection accuracy and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the circuit principle diagram of the positive half cycle comparator in the existing power factor correction circuit;

[0018] Figure 2 It is a circuit schematic diagram of a negative half-cycle comparator in an existing power factor correction circuit;

[0019] Figure 3 It is a structural schematic diagram of a power factor correction circuit provided by an embodiment of the present invention;

[0020] Figure 4 is a circuit schematic diagram of a bias voltage module provided in an embodiment of the present invention;

[0021] Figure 5 is a circuit schematic diagram of a computing module provided by an embodiment of the present invention;

[0022] Figure 6 is a circuit schematic diagram of a comparison module provided in an embodiment of the present invention;

[0023] Figure 7 It is a circuit principle diagram of a power factor correction circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "bottom" and the like used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are used only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0025] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0026] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0027] The technical solution in this application will be described below in conjunction with the accompanying drawings.

[0028] like Figure 1 and Figure 2 As shown, the existing detection circuit uses two independent comparison circuits to detect the positive and negative half cycles of the AC voltage signal Vac respectively. In the positive half cycle detection circuit, the negative input terminal of the operational amplifier is connected to the ACN terminal of the AC voltage signal Vac through the resistor R1, and the positive input terminal is connected to the ACL terminal through the resistor R1, ACL is the voltage at one end of the AC voltage signal Vac, and ACN is the voltage at the other end of the AC voltage signal Vac; at the same time, the feedback resistor R2 is connected between the output terminal and the negative input terminal of the operational amplifier. In the negative half cycle detection circuit, the connection relationship of the input terminal of the operational amplifier is opposite, but the resistor configuration method is the same.

[0029] from Figure 1 We can get a set of equations: (ACL-VIP) / R1=VIP / R2, (ACN-VIN) / R1=(VIN-VO) / R2. Due to the operational amplifier virtual short principle, VIP is approximately equal to VIN, so VO=R2 / R1(ACL-ACN) can be obtained. As long as the resistance values ​​of R1 and R2 are set to the same, VO=ACL-ACN can be obtained.

[0030] When the comparator determines that the AC voltage signal Vac is in the negative half cycle, we use ACN-ACL as the input of the detection comparator, such as Figure 2 As shown:

[0031] from Figure 2 We can get a set of equations: (ACN-VIP) / R1=VIP / R2, (ACL-VIN) / R1=(VIN-VO) / R2. Then we can get VO=R2 / R1(ACN-ACL). As long as the resistance values ​​of R1 and R2 are set to the same, we can get VO=ACN-ACL.

[0032] The above detection scheme requires two independent operational amplifier circuits to process the positive and negative half-cycle signals respectively, and also requires an additional comparator to judge the positive and negative half-cycles, which increases the number of components and costs, as well as the wiring difficulty and failure risk.

[0033] To solve the above problems, the present invention provides a power factor correction circuit, such as Figure 3 As shown, the power factor correction circuit includes three main functional modules: a bias voltage module 100, an operation module 200 and a comparison module 300. The modules form a complete circuit system through specific connection relationships. The output end of the bias voltage module 100 is connected to both the operation module 200 and the comparison module 300; the output end of the operation module 200 is connected to the comparison module 300.

[0034] The bias voltage module 100 has two key functions: first, generating a preset bias voltage; second, generating a positive half-cycle reference voltage and a negative half-cycle reference voltage based on the generated preset bias voltage. Through the design of this module, a stable and reliable reference benchmark can be provided for subsequent signal processing. The setting of the bias voltage needs to consider the circuit working conditions and actual application requirements to ensure that the system can work normally within the appropriate voltage range.

[0035] The operation module 200 mainly completes two tasks: first, receiving the input AC voltage signal; second, performing operation processing on the received AC voltage signal and the preset bias voltage, and outputting a difference signal. This module uses a precise signal processing circuit to ensure that the output difference signal can accurately reflect the changing characteristics of the input AC voltage. The design of the operation module needs to fully consider the accuracy and stability requirements of signal processing.

[0036] The comparison module 300 performs the final signal judgment work, which specifically includes two steps: first, the difference signal output by the operation module is compared with the positive half-cycle reference voltage and the negative half-cycle reference voltage respectively; second, an indication signal is generated based on the comparison result to characterize the polarity state and amplitude of the AC voltage signal. The design of the comparison module needs to ensure comparison accuracy and response speed to meet actual application requirements.

[0037] When the input AC voltage signal enters the circuit system, it is first processed by the bias voltage module 100 to generate the required reference voltage. Subsequently, the operation module 200 receives the AC voltage signal and performs operations with the preset bias voltage to obtain a difference signal that is always greater than 0. Finally, the comparison module 300 compares and judges the difference signal and outputs the final indication signal. The whole process forms a complete signal processing chain to achieve effective detection of the AC voltage signal.

[0038] The comparison module 300 outputs a corresponding indication signal by comparing the relative magnitude relationship between the difference signal and the reference voltage. The reference voltage is divided into two reference values, namely, the positive half-cycle reference voltage and the negative half-cycle reference voltage, which are used for judging the positive and negative half-cycles respectively. When the difference signal is compared with the reference voltage, a corresponding level change will be generated according to the comparison result, thereby forming an indication signal.

[0039] When judging the polarity state of the AC voltage signal, the comparison module 300 adopts a double comparison strategy. When the difference signal is greater than the positive half-cycle reference voltage, it indicates that it is currently in the positive half-cycle state; when the difference signal is less than the negative half-cycle reference voltage, it indicates that it is in the negative half-cycle state. By setting a suitable reference voltage threshold, the polarity change of the AC voltage signal can be accurately identified.

[0040] For the detection of the amplitude, the comparison module 300 is implemented by comparing the difference signal with reference voltages of different gears. By setting multiple reference voltage levels, the amplitude of the AC voltage signal can be divided into different intervals. When the difference signal exceeds a certain reference voltage level, the corresponding comparator outputs a corresponding indication signal, thereby realizing the graded judgment of the amplitude.

[0041] Through the above circuit structure design, the present invention achieves the following technical effects: first, by comparing the difference signal with the positive and negative half-cycle reference voltages selected respectively, the polarity and amplitude of the AC voltage signal are successfully detected; second, the use of additional comparators is avoided, simplifying the circuit structure; third, the overall cost is reduced; fourth, the detection accuracy and reliability are improved. The circuit structure is suitable for various occasions where AC voltage signal detection is required, and has good practical value.

[0042] The bias voltage module of the present invention adopts a structure combining a voltage generating unit and a voltage output unit. Figure 4 As shown, the bias voltage module includes two main parts: a voltage generating unit 110 and a voltage output unit 120. The voltage generating unit 110 is composed of an operational amplifier AMP2, a transistor M1, and resistors R6 and R7. The operational amplifier AMP2 has three main interfaces: an inverting input terminal, a non-inverting input terminal, and an output terminal. The transistor M1 is a PMOS tube, having three terminals: a gate, a source, and a drain. The resistors R6 and R7 form a feedback network through a specific connection method.

[0043] The inverting input terminal of the operational amplifier AMP2 is directly connected to the reference voltage source VREF, and the non-inverting input terminal of the operational amplifier AMP2 is simultaneously connected to the second end of the resistor R6 and the first end of the resistor R7. The output terminal of the operational amplifier AMP2 is connected to the gate of the transistor M1, and the drain of the transistor M1 is connected to the first end of the resistor R6 and is led to the input terminal of the voltage output unit 120. The source of the transistor M1 is connected to the power supply voltage VCC to provide the working voltage for the entire circuit.

[0044] The voltage output unit 120 is mainly composed of n series-connected voltage-dividing resistors R11, R12 to R1n, where n is not less than 3. Voltage-dividing points are formed between adjacent voltage-dividing resistors to provide outputs of different voltage levels. The voltage value of each voltage-dividing point is divided according to a specific relationship to ensure that the required voltage detection range can be covered.

[0045] When the reference voltage source VREF provides a stable reference voltage, the operational amplifier AMP2 generates the required preset bias voltage VOS through negative feedback in cooperation with the resistors R6 and R7. The transistor M1 operates in the saturation region under the control of the operational amplifier AMP2 to ensure the stability of the output voltage. By adjusting the resistance ratio of the resistors R6 and R7, the size of the preset bias voltage can be flexibly set.

[0046] After receiving the preset bias voltage, the voltage output unit 120 performs uniform voltage division through n series-connected voltage divider resistors. The voltage Vk at each voltage dividing point k satisfies a specific calculation formula: Vk = VOS × (nk) / n, where the value range of k is 1 to n-1. Through the voltage divider network, a series of decreasing voltage values ​​can be generated, which are respectively used as the positive half-cycle reference voltage VAC_POS_REF and the negative half-cycle reference voltage VAC_NEG_REF.

[0047] By adjusting the resistance of the voltage divider resistor, the reference voltage distribution can be precisely controlled. The positive half-cycle reference voltage selects the voltage divider point in the higher voltage range, while the negative half-cycle reference voltage selects the voltage divider point in the lower voltage range. By reasonably setting the number of voltage divider points and the voltage divider ratio, the reference voltage requirements of different application scenarios can be met. This design has high flexibility and adjustability.

[0048] The specific working principle is as follows: the operational amplifier AMP2 receives the reference voltage provided by the reference voltage source and converts it into a stable driving signal through the voltage follower circuit. Under the control of the driving signal, the transistor M1 converts the voltage of the power supply into a preset bias voltage VOS.

[0049] The present invention provides a computing module, the circuit schematic diagram of which is as follows Figure 5As shown, the operation module 200 uses an operational amplifier AMP1 and resistors R1, R2, R3, R4 and R5 to form a differential operation circuit. The operational amplifier AMP1 has three main interfaces: a non-inverting input terminal, an inverting input terminal and an output terminal. The resistors R1, R2, R3, R4 and R5 form an input network and a feedback network through a specific connection method to jointly complete the signal operation function.

[0050] The first end of the resistor R1 is connected to the first end (ACL end) of the AC voltage signal source. The second end of the resistor R1 is connected to the first end of the resistor R5 and the inverting input end of the operational amplifier AMP1 at the same time. The first end of the resistor R2 is connected to the second end (ACN end) of the AC voltage signal source. The second end of the resistor R2 is connected to the non-inverting input end of the operational amplifier AMP1. This connection method ensures the correct sampling of the AC voltage signal.

[0051] The first end of the resistor R3 is connected to the bias voltage output end of the bias voltage module 100, and is used to introduce a preset bias voltage VOS. The second end of the resistor R3 forms a three-point connection with the first end of the resistor R4 and the in-phase input end of the operational amplifier AMP1. The second end of the resistor R4 is grounded. Through this structure, the preset bias voltage VOS can be introduced into the operational circuit to provide a reference for subsequent signal processing.

[0052] The output end of the operational amplifier AMP1 is connected to the second end of the resistor R5, and is also used as the output end of the operation module 200 to be led to the positive input end of the comparison module 300. In this structure, the input AC voltage signal and the bias voltage are reasonably operated through a well-designed resistor network in conjunction with the operation characteristics of the operational amplifier, and the desired difference signal is finally output.

[0053] To ensure the normal operation of the circuit, the resistance values ​​of resistors R1, R2 and R3 need to be equal. At the same time, resistors R1, R4 and R5 need to satisfy a specific mathematical relationship: R5 / R4 = (R1+R5) / (R1+2R4). By strictly controlling the matching relationship of the resistor parameters, the accuracy and stability of the calculation results can be guaranteed.

[0054] Based on the virtual short characteristics of the operational amplifier and the voltage-dividing characteristics of the resistor network, there is a fixed mathematical relationship between the output voltage VO and the input signal. When the resistor parameters meet the design requirements, the output voltage can accurately reflect the difference between the input AC voltage signal and the bias voltage, providing a reliable signal basis for subsequent comparison and judgment.

[0055] By adjusting the resistance parameters, the circuit gain and bias characteristics can be precisely controlled. This design is highly flexible and can adapt to the needs of different application scenarios. At the same time, through reasonable circuit layout and device selection, common-mode interference can be effectively suppressed and the circuit's anti-noise ability can be improved.

[0056] The present invention provides a comparison module, the circuit schematic diagram of which is as follows Figure 6 As shown, the comparison module 300 uses two voltage comparators COMP1 and COMP2 to form a dual-channel comparison circuit. Both comparators have a non-inverting input terminal, an inverting input terminal and an output terminal. Through a reasonable connection method, two independent signal detection channels for the positive half cycle and the negative half cycle are formed to achieve comprehensive monitoring of the AC voltage signal.

[0057] The inverting input terminals of the comparator COMP1 and the comparator COMP2 are connected to the output terminal of the operation module 200 for receiving the difference signal VO. The inverting input terminal of the comparator COMP1 is connected to the positive half-cycle output terminal of the bias voltage module 100 for receiving the positive half-cycle reference voltage VAC_POS_REF. The non-inverting input terminal of the comparator COMP2 is connected to the negative half-cycle output terminal of the bias voltage module 100 for receiving the negative half-cycle reference voltage VAC_NEG_REF.

[0058] When the AC voltage signal is in the positive half cycle, the comparator COMP1 is responsible for comparing the difference signal with the positive half cycle reference voltage. If the difference signal exceeds the positive half cycle reference voltage, the comparator COMP1 outputs a high level and generates a first amplitude indication signal VAC_POS_COMP, indicating that the amplitude of the AC voltage signal reaches the preset threshold.

[0059] When the AC voltage signal enters the negative half cycle, the comparator COMP2 takes over the detection task and compares the difference signal with the negative half cycle reference voltage. When the difference signal is lower than the negative half cycle reference voltage, the comparator COMP2 outputs a high level and generates a second amplitude indication signal VAC_NEG_COMP, indicating the voltage amplitude state of the negative half cycle.

[0060] By setting the reference voltage appropriately, smooth switching can be achieved near the signal zero crossing point to avoid judgment dead zones or overlapping zones. This design effectively eliminates the need for negative voltage comparators in traditional solutions.

[0061] The output signals VAC_POS_COMP and VAC_NEG_COMP of the two comparators indicate the amplitude states of the positive and negative half cycles respectively. The output signals are in digital level form, which is convenient for subsequent circuit processing. By analyzing the timing relationship of the two output signals, the polarity state and amplitude of the AC voltage signal can be accurately determined.

[0062] To improve the reliability of the circuit, the selection of the comparator needs to consider the response speed and accuracy requirements. By adding an appropriate filtering circuit, the noise interference of the input signal can be suppressed. At the same time, the hysteresis characteristic design of the comparator also needs to be reasonable to prevent jitter near the reference voltage. This solution has the advantages of simple structure, low cost and high detection accuracy.

[0063] A circuit schematic diagram of a power factor correction circuit provided by an embodiment of the present invention is shown in FIG. Figure 7 As shown, the power factor correction circuit system adopts a modular design scheme, and mainly includes three functional units: a bias voltage module 100, a calculation module 200, and a comparison module 300. The bias voltage module 100 is provided with two sub-units: a voltage generation unit 110 and a voltage output unit 120. Figure 7 The detailed connection relationship between each module and the internal circuit structure are shown.

[0064] according to Figure 5 We can get a system of equations:

[0065] (ACL-VIP) / R1+(VOS-VIP) / R1=(VIP-0) / R4,

[0066] (ACN-VIN) / R1=(VIN-VO) / R5.

[0067] Then we can get:

[0068] VO=(R4×(R1+R5)) / (R1×(R1+2R4))×(ACL+VOS)-R5 / R1×ACN,

[0069] Therefore, VOS can be set to ensure that ACL-ACN+VOS is greater than 0 in all cases, successfully avoiding the need to distinguish between positive and negative half cycles and use a negative voltage comparator.

[0070] The voltage generating unit 110 of the bias voltage module 100 is composed of an operational amplifier AMP1, a PMOS tube M1 and resistors R6 and R7. The reference voltage VREF is input to the inverting input terminal of the operational amplifier AMP1, and a preset bias voltage VOS is generated through negative feedback. The voltage output unit 120 is composed of n series-connected voltage-dividing resistors R11, R12 to R1n to form a voltage-dividing network, generating a positive half-cycle reference voltage VAC_POS_REF and a negative half-cycle reference voltage VAC_NEG_REF.

[0071] Due to the virtual short and virtual disconnect principle of the operational amplifier, it can be concluded that:

[0072] VOS=(R1+R4) / R4*VREF.

[0073] Connecting n resistors in series under the VOS voltage can obtain n + 1 voltages ranging from 0 to VOS, and the difference between adjacent two is VOS / n. The positive half-cycle reference voltage VAC_POS_REF is selected as the voltage at the voltage dividing point greater than the preset median value, and the negative half-cycle reference voltage VAC_NEG_REF is selected as the voltage at the voltage dividing point less than the preset median value. The preset median value Vmiddle is calculated by the formula Vmiddle = R5 / R1 × VOS. The voltage greater than R5 / R1*VOS is the positive half-cycle reference voltage VAC_POS_REF, and the voltage less than R5 / R1*VOS is the negative half-cycle reference voltage VAC_NEG_REF.

[0074] The operation module 200 includes an operational amplifier AMP1 and five precision resistors R1 - R5. The operational amplifier AMP1 adopts a differential input structure and realizes the signal operation function through a resistor network. The AC voltage signal is input from the ACL and ACN terminals, and after being divided by the resistors R1 and R2, it is sent to the operational amplifier. At the same time, the preset bias voltage VOS is introduced into the circuit through the resistor R3 and is processed in operation with the input signal.

[0075] By setting the number of resistor strings in the bias voltage module 100 and selecting two different types of voltages (the positive half-cycle reference voltage VAC_POS_REF and the negative half-cycle reference voltage VAC_NEG_REF), it is possible to detect different voltage amplitudes in the positive and negative half-cycles of Vac, and it is possible to achieve surge protection for the input voltage Vac.

[0076] The comparison module 300 is composed of two voltage comparators COMP1 and COMP2 to form a dual-channel comparison circuit. The non-inverting input terminal of the comparator COMP1 and the inverting input terminal of the comparator COMP2 are connected to the output terminal VO of the operation module. The inverting input terminal of COMP1 receives the positive half-cycle reference voltage, while the non-inverting input terminal of COMP2 receives the negative half-cycle reference voltage. Two indication signals VAC_POS_COMP and VAC_NEG_COMP are output through comparison operation.

[0077] The positive half-cycle reference voltage VAC_POS_REF > R5 / R1*VOS, that is, for the comparator COMP1, R3 / R1(ACL + VOS - ACN) = VAC_POS_REF, so it means ACL - ACN > 0, so the comparator COMP1 corresponds to the detection of the positive half-cycle voltage amplitude; the negative half-cycle reference voltage VAC_NEG_REF < R3 / R1*VOS, that is, for the comparator COMP2, R3 / R1(ACL + VOS - ACN) = VAC_NEG_REF, so it means ACL - ACN < 0, so the comparator COMP2 corresponds to the detection of the negative half-cycle voltage amplitude.

[0078] It should be noted that the circuit schematic provided in this embodiment is used to detect the positive half cycle and the negative half cycle of the AC voltage signal. If only the positive half cycle or the negative half cycle needs to be detected separately, only comparator COMP1 or comparator COMP2 can be retained.

[0079] To ensure the normal operation of the circuit, the parameter settings of each module need to be strictly controlled. In the bias voltage module, the value of the voltage divider resistor must satisfy the relationship Vk = VOS × (nk) / n. The resistance values ​​of resistors R1, R2, and R3 in the operation module are equal, and R5 / R4 = (R1 + R5) / (R1 + 2R4).

[0080] The AC voltage signal is first conditioned by the operation module 200 and is operated together with the preset bias voltage VOS to generate a difference signal. The difference signal is then sent to the comparison module 300 and compared with the positive and negative half-cycle reference voltages respectively.

[0081] Different from the prior art, the implementation mode of the present invention realizes the detection of the polarity and amplitude of the AC voltage signal by comparing the difference signal with the positive and negative half-cycle reference voltages selected respectively, avoids the use of a negative voltage comparator, simplifies the circuit structure, reduces the cost, and improves the detection accuracy and reliability.

[0082] Based on the power factor correction circuit provided in the above embodiments, an embodiment of the present invention further provides a power factor correction device, which includes the power factor correction circuit provided in any of the above embodiments.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A power factor correction circuit, characterized in that: include: A bias voltage module is configured to generate a preset bias voltage, and generate a positive half-cycle reference voltage and a negative half-cycle reference voltage based on the preset bias voltage; A calculation module, configured to receive an AC voltage signal and output a difference signal according to the AC voltage signal and the preset bias voltage; The comparison module is configured to compare the difference signal with the positive half-cycle reference voltage and the negative half-cycle reference voltage respectively, and generate an indication signal indicating the polarity and amplitude of the AC voltage signal.

2. The circuit according to claim 1, characterized in that The bias voltage module includes a voltage generating unit and a voltage output unit. The voltage generating unit is configured to generate the preset bias voltage according to a reference voltage provided by a reference voltage source; The voltage output unit is configured to generate the positive half-cycle reference voltage and the negative half-cycle reference voltage according to the preset bias voltage.

3. The circuit according to claim 2, characterized in that The voltage generating unit includes an operational amplifier AMP2, a transistor M1, a resistor R6 and a resistor R7, The inverting input terminal of the operational amplifier AMP2 is connected to the reference voltage source, the non-inverting input terminal of the operational amplifier AMP2 is connected to the second end of the resistor R6 and the first end of the resistor R7, the output terminal of the operational amplifier AMP2 is connected to the gate of the transistor M1, the drain of the transistor M1 is connected to the first end of the resistor R6 and the input terminal of the voltage output unit, and the source of the transistor M1 is connected to a power supply.

4. The circuit according to claim 2, characterized in that The voltage output unit comprises n voltage-dividing resistors connected in series, n≥3, and the connection points of adjacent voltage-dividing resistors constitute voltage-dividing points; The voltage Vk of the kth voltage dividing point satisfies: Vk=VOS×(nk) / n, wherein the value range of k is 1 to n-1, and VOS is the preset bias voltage.

5. The circuit according to claim 1, characterized in that The operation module includes: an operational amplifier AMP1, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a resistor R5, The first end of the resistor R1 is connected to the first end of the AC voltage signal source, the second end of the resistor R1 is connected to the first end of the resistor R5 and the inverting input end of the operational amplifier AMP1, the first end of the resistor R2 is connected to the second end of the AC voltage signal source, and the second end of the resistor R2 is connected to the non-inverting input end of the operational amplifier AMP1; The first end of the resistor R3 is connected to the bias voltage output end of the bias voltage module, the second end of the resistor R3 is connected to the first end of the resistor R4 and the in-phase input end of the operational amplifier AMP1, and the output end of the operational amplifier AMP1 is connected to the second end of the resistor R5 and the positive input end of the comparison module.

6. The circuit according to claim 5, characterized in that The resistance values ​​of the resistor R1, the resistor R2 and the resistor R3 are equal, and the resistor R1, the resistor R4 and the resistor R5 satisfy: R5 / R4=(R1+R5) / (R1+2R4).

7. The circuit according to claim 5, characterized in that The positive half-cycle reference voltage is any voltage at a voltage division point greater than a first preset value, and the negative half-cycle reference voltage is any voltage at a voltage division point less than the first preset value; The first preset value is calculated according to the following formula: In middle =R5 / R1×VOS.

8. The circuit according to claim 1, characterized in that The comparison module includes a comparator COMP1 and a comparator COMP2. The non-inverting input terminal of the comparator COMP1 is connected to the inverting input terminal of the comparator COMP2 and the output terminal of the operation module, the inverting input terminal of the comparator COMP1 is connected to the positive half-cycle output terminal of the bias voltage module, and the non-inverting input terminal of the comparator COMP2 is connected to the negative half-cycle output terminal of the bias voltage module.

9. The circuit according to claim 8, characterized in that When the AC voltage signal is in a positive half cycle, the comparator COMP1 compares the difference signal with the positive half cycle reference voltage, and outputs a first amplitude indication signal when the difference signal exceeds the positive half cycle reference voltage; When the AC voltage signal is in a negative half cycle, the comparator COMP2 compares the difference signal with the negative half cycle reference voltage, and outputs a second amplitude indication signal when the difference signal is lower than the negative half cycle reference voltage.

10. A power factor correction device, characterized in that: include: A power factor correction circuit as claimed in any one of claims 1 to 9.

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