Isolation current sampling circuit of LLC resonant converter

Abstract

The utility model discloses an isolation current sampling circuit of an LLC resonant converter, which comprises a half-bridge LLC resonant circuit and a processing circuit, a resonant unit is connected in the half-bridge LLC resonant circuit, the resonant unit is electrically connected with the processing circuit, and the processing circuit is used for rectifying and filtering primary current IP passing through the half-bridge LLC resonant circuit. The resonance unit comprises a resonance inductor and a sampling winding, the sampling winding is wound in a magnetic core in the resonance inductor to serve as a secondary winding, the sampling winding is electrically connected with the processing circuit, current sampling is achieved, an original current transformer is replaced by the integrated design of the resonance inductor and the sampling winding, the design space on a plate is effectively reduced, and the cost is reduced. And meanwhile, the cost is also reduced.

Description

Technical Field

[0001] The utility model relates to the field of electronic technology, in particular to an isolated current sampling circuit of an LLC resonant converter. Background Art

[0002] In a traditional LLC resonant circuit, if it is necessary to monitor the current during LLC circuit operation and to perform overcurrent protection on the primary side, a current transformer needs to be added to the main circuit for isolated sampling to monitor the operating current in the circuit. However, as the power increases, the size of the current transformer will also increase, and the cost will also increase. Utility Model Content

[0003] The purpose of the utility model is to address the technical problems existing in the background technology and to propose an isolated current sampling circuit for an LLC resonant converter.

[0004] In order to achieve the above technical objectives, the technical solutions adopted in the first aspect of the present invention are as follows:

[0005] An isolated current sampling circuit for an LLC resonant converter includes a half-bridge LLC resonant circuit and a processing circuit. A resonant unit is connected to the half-bridge LLC resonant circuit, and the resonant unit is electrically connected to the processing circuit. The processing circuit is used to rectify and filter the primary current IP passing through the half-bridge LLC resonant circuit. The resonant unit includes a resonant inductor and a sampling winding. The sampling winding is wound within a magnetic core in the resonant inductor to serve as a secondary winding. The sampling winding is electrically connected to the processing circuit.

[0006] Preferably, the processing circuit includes a first input unit, a second input unit, a resistor R5, a resistor R6, a resistor R7, a diode D1 and a filter capacitor C3. The first input unit and the second input unit are electrically connected to the two ends of the sampling winding respectively, the resistor R5, the diode D1 and the resistor R8 are connected in series in sequence, one end of the resistor R5 is electrically connected to the first input unit, the filter capacitor C3 is connected in parallel with the resistor R7, the first end of the resistor R7 is electrically connected to the negative electrode of the diode D1, the second end of the resistor R7 is electrically connected to the resistor R6 and grounded, and the resistor R6 is electrically connected to the second input unit.

[0007] Preferably, the processing circuit further includes a DSP chip, which is electrically connected to the resistor R8 for receiving the rectified and filtered primary current IP and using it as a protection signal source.

[0008] Compared with the prior art, the utility model has the following beneficial technical effects: by including a half-bridge LLC resonant circuit and a processing circuit, a resonant unit is connected in the half-bridge LLC resonant circuit, the resonant unit is electrically connected to the processing circuit, the processing circuit is used to rectify and filter the primary current IP passing through the half-bridge LLC resonant circuit, the resonant unit includes a resonant inductor and a sampling winding, the sampling winding is wound in the magnetic core of the resonant inductor as a secondary winding, the sampling winding is electrically connected to the processing circuit to realize current sampling, and the integrated design of the resonant inductor and the sampling winding replaces the original current transformer, effectively reducing the design space on the board and also reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 2 is a circuit diagram of a half-bridge LLC resonant circuit in an embodiment of the present utility model;

[0010] Figure 2 2 is a circuit diagram of a processing circuit in an embodiment of the present utility model.

[0011] Reference numerals: 100 half-bridge LLC resonant circuit, 101 resonant unit, 200 processing circuit, 201 first input unit, 202 second input unit, 203 DSP chip. DETAILED DESCRIPTION

[0012] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0013] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0014] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connection, connection, or specific connection; they can refer to mechanical connection or electrical connection; they can refer to direct connection or indirect connection through an intermediate medium; and they can refer to internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0015] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0016] like Figure 1 - Figure 2 As shown, the present invention proposes an isolated current sampling circuit for an LLC resonant converter, which includes a half-bridge LLC resonant circuit 100 and a processing circuit 200. A resonant unit 101 is connected to the half-bridge LLC resonant circuit 100, and the resonant unit 101 is electrically connected to the processing circuit 200. The processing circuit 200 is used to rectify and filter the primary current IP passing through the half-bridge LLC resonant circuit 100. The resonant unit 101 includes a resonant inductor and a sampling winding. The sampling winding is wound in a magnetic core in the resonant inductor to serve as a secondary winding, and the sampling winding is electrically connected to the processing circuit 200.

[0017] See attached Figure 1 The half-bridge LLC resonant circuit 100 also includes a primary-side switch Q1, a primary-side switch Q2, an output-end synchronous rectifier MOS_Q4, an output-end synchronous rectifier MOS_Q5, a filter capacitor Co, and a load Rload. During actual operation, when the load Rload increases, the current IP in the half-bridge LLC resonant circuit 100 will increase accordingly, and the current flowing in series through the resonant unit 101 will also increase. For example, the resonant inductor and the sampling winding in the resonant unit 101 have a turns ratio of 10:1, so the voltage signal of the resonant unit 101 will also increase year-on-year. At this time, the processing circuit 200 restores the voltage waveform that follows the primary current IP, thereby realizing current sampling. In addition, the integrated design of the resonant inductor and the sampling winding replaces the original current transformer, effectively reducing the design space on the board and also reducing costs.

[0018] Furthermore, the processing circuit 200 includes a first input unit 201, a second input unit 202, a resistor R5, a resistor R6, a resistor R7, a diode D1 and a filter capacitor C3. The first input unit 201 and the second input unit 202 are respectively electrically connected to the two ends of the sampling winding, the resistor R5, the diode D1 and the resistor R8 are connected in series in sequence, one end of the resistor R5 is electrically connected to the first input unit 201, the filter capacitor C3 is connected in parallel with the resistor R7, the first end of the resistor R7 is electrically connected to the negative electrode of the diode D1, the second end of the resistor R7 is electrically connected to the resistor R6 and grounded, and the resistor R6 is electrically connected to the second input unit 202.

[0019] The processing circuit 200 further includes a DSP chip 203 . The DSP chip 203 is electrically connected to the resistor R8 for receiving the rectified and filtered primary current IP and using it as a protection signal source.

[0020] Specifically, in actual operation, when the load Rload changes, the current IP in the half-bridge LLC resonant circuit 100 and the current flowing in series through the resonant unit 101 will also change accordingly. According to the resonant inductance in the resonant unit 101 and the turns ratio of the sampling winding, the voltage signal of the resonant unit 101 will also increase or decrease year-on-year according to the turns ratio. At this time, the processing circuit 200 restores it to obtain a voltage waveform that follows the primary current IP, and then samples the current. The voltage is sent to the DSP control, which can be used as a signal source for protection functions such as overcurrent, thereby realizing current protection for the half-bridge LLC resonant circuit 100.

[0021] The above descriptions provide one or more embodiments in conjunction with the specific content, and do not limit the specific implementation of the present invention to these descriptions. Any similarity or similarity with the methods, structures, etc. of the present invention, or any technical deduction or substitution based on the concept of the present invention, shall be deemed to be within the scope of protection of the present invention.

Claims

1. An isolated current sampling circuit for an LLC resonant converter, characterized in that: It includes a half-bridge LLC resonant circuit (100) and a processing circuit (200); A resonance unit (101) is connected to the half-bridge LLC resonant circuit (100), the resonance unit (101) is electrically connected to the processing circuit (200), and the processing circuit (200) is used to rectify and filter the primary current IP passing through the half-bridge LLC resonant circuit (100); The resonant unit (101) comprises a resonant inductor and a sampling winding, the sampling winding is wound inside a magnetic core of the resonant inductor to serve as a secondary winding, and the sampling winding is electrically connected to the processing circuit (200).

2. The isolated current sampling circuit of an LLC resonant converter according to claim 1, characterized in that: The processing circuit (200) comprises a first input unit (201), a second input unit (202), a resistor R5, a resistor R6, a resistor R7, a diode D1 and a filter capacitor C3. The first input unit (201) and the second input unit (202) are electrically connected to two ends of the sampling winding, respectively. The resistor R5, the diode D1 and the resistor R8 are connected in series in sequence. One end of the resistor R5 is electrically connected to the first input unit (201). The filter capacitor C3 is connected in parallel to the resistor R7. The first end of the resistor R7 is electrically connected to the negative electrode of the diode D1. The second end of the resistor R7 is electrically connected to the resistor R6 and is grounded. The resistor R6 is electrically connected to the second input unit (202).

3. The isolated current sampling circuit of an LLC resonant converter according to claim 2, characterized in that: The processing circuit (200) further comprises a DSP chip (203), wherein the DSP chip (203) is electrically connected to the resistor R8 and is used to receive the rectified and filtered primary current IP and use it as a protection signal source.

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