PFC circuit using isolation amplifier

Abstract

The utility model belongs to the technical field of switching power supplies, and discloses a PFC circuit using an isolation amplifier, which comprises an isolation amplifier AMC1306 and an MCU, the positive electrode of a power supply is connected with the positive electrode of a diode D1 and one end of a sampling resistor RS2, the other end of the sampling resistor RS2 is respectively connected with the source electrode of an MOS tube Q1 and the drain electrode of an MOS tube Q2 through an inductor L2, and the isolation amplifier AMC1306 and the MCU are respectively connected with the positive electrode of the diode D1 and one end of the sampling resistor RS2. The negative electrode of the power supply is connected with the positive electrode of the diode D2, the source electrode of the MOS tube Q3 and the drain electrode of the MOS tube Q4, and the isolation amplifier AMC1306 is connected with the sampling resistor RS2 and the MCU and is used for transmitting the sampling value of the sampling resistor RS2. The beneficial effects of the utility model are that the circuit is simple, the cost is low, and the functions of current loop control and input precision calculation can be simultaneously satisfied.

Description

Technical Field

[0001] The utility model relates to the technical field of switch power supplies, in particular to a PFC circuit using an isolation amplifier. Background Art

[0002] With the rapid development of society, electronic technology has been widely used in various fields, and the types of electronic equipment are increasing. Electronic equipment is becoming increasingly closely related to our lives. More importantly, it is inseparable from the support of power supply, and the quality requirements of power supply are getting higher and higher. We hope to obtain high-power power supply equipment with high power density, high efficiency, no grid pollution, and no electromagnetic interference. Therefore, how to simplify complex circuits has become a research direction for improving power density.

[0003] At present, the traditional PFC control scheme that uses meter IC for input accuracy and hall IC for current loop control is not only complex in circuit but also high in cost, which is not conducive to the development of high power density products. Therefore, it is necessary to provide a PFC circuit using an isolation amplifier. The scheme using a new isolation amplifier (AMC1306) in PFC control has a simple circuit and low cost, and can simultaneously meet the current loop control and input accuracy calculation functions. Utility Model Content

[0004] The utility model discloses a PFC circuit using an isolation amplifier, which can effectively solve the technical problems involved in the background technology.

[0005] To achieve the above purpose, the technical solution of the utility model is:

[0006] A PFC circuit using an isolation amplifier comprises an isolation amplifier AMC1306 and an MCU, wherein the positive electrode of a power supply is connected to the positive electrode of a diode D1 and one end of a sampling resistor RS2, the other end of the sampling resistor RS2 is respectively connected to the source of a MOS transistor Q1 and the drain of a MOS transistor Q2 through an inductor L2, the negative electrode of the power supply is connected to the positive electrode of a diode D2, the source of a MOS transistor Q3 and the drain of a MOS transistor Q4, the negative electrode of the diode D1, the negative electrode of the diode D2, the drain of the MOS transistor Q1, the drain of the MOS transistor Q3 and one end of a capacitor C1 are connected to one end of a load, the source of the MOS transistor Q2, the source of the MOS transistor Q4 and the other end of the capacitor C1 are connected to the other end of the load, the isolation amplifier AMC1306 is connected to the sampling resistor RS2 and the MCU and is used to transmit the sampled value of the sampling resistor RS2, and the gates of the MOS transistor Q1, the gates of the MOS transistor Q2, the gates of the MOS transistor Q3 and the gates of the MOS transistor Q4 are connected to the MCU.

[0007] As a preferred improvement of the present utility model: the isolation amplifier AMC1306 includes pin AINP, pin AINN, pin DOUT and pin CLKIN, pin AINN of the isolation amplifier AMC1306 is connected to one end of the sampling resistor RS2, pin AINP is connected to the other end of the sampling resistor RS2, pin DOUT is connected to pin SD-DX of the MCU, and pin CLKIN is connected to pin SD-CX of the MCU.

[0008] As a preferred improvement of the present invention: the MCU is also connected to the power supply and the capacitor C1 for voltage sampling.

[0009] As a preferred improvement of the present invention: the MCU model is TMS320F280039.

[0010] As a preferred improvement of the present invention: the power supply is AC or DC mains.

[0011] As a preferred improvement of the utility model: the PFC circuit further includes an EMI filter circuit, and the power supply is connected to the diode D1, the diode D2, the sampling resistor RS2, the MOS tube Q3 and the MOS tube Q4 through the EMI filter circuit.

[0012] The beneficial effects of the utility model are as follows:

[0013] The new isolation amplifier AMC1306 is used for current sampling in the PFC topology. Compared with the traditional PFC topology, the PFC circuit structure is simpler and more space-saving, which can greatly reduce the circuit cost and meet the current loop control and input accuracy calculation functions at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0015] Figure 1 It is a schematic diagram of a PFC circuit using an isolation amplifier of the utility model;

[0016] Figure 2 Schematic diagram of the totem pole PFC working framework of traditional HALL IC and meterIC;

[0017] Figure 3 This is a schematic diagram of the working framework of the isolation amplifier AMC1306;

[0018] Figure 4 This is the output drive schematic diagram of the isolation amplifier AMC1306;

[0019] Figure 5 It is the schematic diagram of SFDM filtering;

[0020] Figure 6 This is the pin diagram of the isolation amplifier AMC1306;

[0021] Figure 7 This is a schematic diagram of the EMI filter circuit. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0024] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0025] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0027] See also Figure 1 As shown, the utility model provides a PFC circuit using an isolation amplifier, including an isolation amplifier AMC1306 and an MCU, the positive electrode of the power supply is connected to the positive electrode of the diode D1 and one end of the sampling resistor RS2, the other end of the sampling resistor RS2 is respectively connected to the source of the MOS tube Q1 and the drain of the MOS tube Q2 through the inductor L2, the negative electrode of the power supply is connected to the positive electrode of the diode D2, the source of the MOS tube Q3 and the drain of the MOS tube Q4, the negative electrode of the diode D1, the negative electrode of the diode D2, the drain of the MOS tube Q1, The drain of the MOS tube Q3 and one end of the capacitor C1 are connected to one end of the load, the source of the MOS tube Q2, the source of the MOS tube Q4 and the other end of the capacitor C1 are connected to the other end of the load, the isolation amplifier AMC1306 is connected to the sampling resistor RS2 and the MCU, and is used to transmit the sampled value of the sampling resistor RS2, the gate of the MOS tube Q1, the gate of the MOS tube Q2, the gate of the MOS tube Q3 and the gate of the MOS tube Q4 are connected to the MCU, and R1 in the figure is equivalent to the load.

[0028] Specifically, AMC1306 samples the analog signal of current through the Sense resistor, and then processes it internally in AMC1306 and outputs the corresponding digital signal through the DOUT PIN. The duty cycle is used to represent the value of the digital signal. Figure 4 After the SFDM module of the MCU receives the driving signal of DOUT, it obtains the corresponding current digital signal after passing through the filter, as shown in Figure 5 As shown. The obtained current digital signal can be used directly for current loop control, and can also be used to calculate the effective value of the input current. The traditional line needs to use a meter IC for accuracy reporting because the DSP's ADC is 12 bits. Due to the limited ADC resolution, it is impossible to achieve the current CRPS accuracy specifications. The SFDM interface has no ADC resolution limit and can filter 16-bit or even higher resolution current signals into corresponding digital signals. The resolution of the current signal is improved, and the current accuracy calculated by the algorithm is naturally higher, P = Vin*Iin, and the accuracy of the input power can naturally be better. The advantages and disadvantages comparison table of traditional lines and new isolation amplifier lines is as follows:

[0029]

[0030] AMC1306 is the latest current sampling chip launched by TI. This solution is to use an AMC1306 to replace the HALL IC and meter IC 6610. The HALL IC is used for current signal sampling, and the meter IC 6610 is used for accuracy reporting. Because the power supply industry has high requirements for accuracy, the MCU alone cannot achieve high-precision specifications through the sampling signal calculation of the HALL IC, while the use of AMC1306 can achieve the same functions of the HALL IC and MERT IC. The PFC circuit structure using AMC1306 is simpler and more space-saving than the traditional PFC circuit structure using HALL IC+meter IC. Compared with the existing PFC circuit, the structure has been innovated to reduce the circuit cost.

[0031] As an implementation manner, the isolation amplifier AMC1306 includes pin AINP, pin AINN, pin DOUT and pin CLKIN, pin AINN of the isolation amplifier AMC1306 is connected to one end of the sampling resistor RS2, pin AINP is connected to the other end of the sampling resistor RS2, pin DOUT is connected to pin SD-DX of the MCU, and pin CLKIN is connected to pin SD-CX of the MCU.

[0032] As an implementation mode, the MCU is also connected to the power supply and the capacitor C1 for voltage sampling (input and output voltage), the MCU model is TMS320F280039 (any MCU with SDFM function can be used), and the power supply is AC or DC.

[0033] The PFC circuit further includes an EMI filter circuit, and the power supply is connected to the diode D1, the diode D2, the sampling resistor RS2, the MOS transistor Q3 and the MOS transistor Q4 through the EMI filter circuit. Figure 7 As shown, it is a common filter circuit, which can be connected to the two ends of the power supply. It should be further explained that the use of other components to achieve the above effects should belong to the inventive concept of the utility model and should belong to the protection scope of the utility model.

[0034] Although the implementation scheme of the utility model has been disclosed as above, it is not limited to the applications listed in the specification and the implementation scheme. It can be fully applied to various fields suitable for the utility model. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A PFC circuit using an isolation amplifier, characterized in that: The invention comprises an isolation amplifier AMC1306 and an MCU, wherein the positive electrode of the power supply is connected to the positive electrode of the diode D1 and one end of the sampling resistor RS2, the other end of the sampling resistor RS2 is respectively connected to the source of the MOS tube Q1 and the drain of the MOS tube Q2 through the inductor L2, the negative electrode of the power supply is connected to the positive electrode of the diode D2, the source of the MOS tube Q3 and the drain of the MOS tube Q4, the negative electrode of the diode D1, the negative electrode of the diode D2, the drain of the MOS tube Q1, the drain of the MOS tube Q3 and one end of the capacitor C1 are connected to one end of the load, the source of the MOS tube Q2, the source of the MOS tube Q4 and the other end of the capacitor C1 are connected to the other end of the load, the isolation amplifier AMC1306 is connected to the sampling resistor RS2 and the MCU, and is used for transmitting the sampled value of the sampling resistor RS2, and the gate of the MOS tube Q1, the gate of the MOS tube Q2, the gate of the MOS tube Q3 and the gate of the MOS tube Q4 are connected to the MCU.

2. A PFC circuit using an isolation amplifier according to claim 1, characterized in that: The isolation amplifier AMC1306 includes pins AINP, AINN, DOUT and CLKIN. Pin AINN of the isolation amplifier AMC1306 is connected to one end of the sampling resistor RS2, pin AINP is connected to the other end of the sampling resistor RS2, pin DOUT is connected to pin SD-DX of the MCU, and pin CLKIN is connected to pin SD-CX of the MCU.

3. A PFC circuit using an isolation amplifier according to claim 1, characterized in that: The MCU is also connected to the power supply and the capacitor C1 for voltage sampling.

4. A PFC circuit using an isolation amplifier according to claim 1, characterized in that: The MCU model is TMS320F280039.

5. The PFC circuit using an isolation amplifier according to claim 1, characterized in that: The power supply is AC or DC.

6. A PFC circuit using an isolation amplifier according to claim 1, characterized in that: The PFC circuit further includes an EMI filter circuit, and the power supply is connected to the diode D1, the diode D2, the sampling resistor RS2, the MOS transistor Q3 and the MOS transistor Q4 through the EMI filter circuit.

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