LLC converter current detection circuit and power supply

Abstract

The invention relates to an LLC converter current detection circuit and a power supply. The detection circuit comprises a first current mutual inductance unit, a second current mutual inductance unit, a signal conditioning unit and a signal conversion unit, the first current mutual inductance unit is coupled with a resonant inductor in the LLC converter, and generates a first voltage signal according to the resonant current of the resonant inductor; the second current mutual inductance unit is coupled with a transformer magnetic core corresponding to an excitation inductor in the LLC converter, and generates a second voltage signal according to the excitation current of the excitation inductor; the signal conditioning unit is connected with the first current mutual inductance unit and the second current mutual inductance unit, and generates a third voltage signal according to the first voltage signal and the second voltage signal; the signal conversion unit is connected with the signal conditioning unit, receives the third voltage signal and converts the third voltage signal into a secondary side output current of the LLC converter according to the third voltage signal. According to the invention, circuit current detection can be realized without complex fitting calculation while the performance of the original circuit is not influenced.

Description

Technical Field

[0001] This invention relates to the field of power supply detection technology, and more specifically, to an LLC converter current detection circuit and power supply. Background Technology

[0002] In power conversion scenarios, sampling is required at different locations in the circuit due to varying purposes. LLC resonant converters typically require sampling of the secondary current to meet dynamic response and overcurrent protection requirements. Traditional sampling schemes for converters mainly fall into two categories. One method uses current transformers, Rogowski coils, Hall effect sensors, etc., to detect loop current. This method requires adding a new device in series with the existing circuit, resulting in a bulky current sampling circuit. This leads to increased leakage inductance and resistance on the transformer secondary side, causing voltage spikes and power losses, which is detrimental to achieving high power density. The other method determines the current at the target location based on the primary current and its correspondence with the current at one or more target locations. While this reduces the number of sampling circuits, it requires curve fitting calculations based on current conversion formulas and a primary-side current transformer (CT) sampling circuit. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an LLC converter current detection circuit and power supply, which addresses the above-mentioned technical defects of the prior art.

[0004] The technical solution adopted by the present invention to solve its technical problem is: to construct an LLC converter current detection circuit, including: a first current transformer unit, a second current transformer unit, a signal conditioning unit and a signal conversion unit;

[0005] The first current transformer unit is coupled to the resonant inductor in the LLC converter and is used to generate a first voltage signal based on the resonant current of the resonant inductor.

[0006] The second current transformer unit is coupled to the transformer core corresponding to the magnetizing inductor in the LLC converter, and is used to generate a second voltage signal based on the magnetizing current of the magnetizing inductor.

[0007] The signal conditioning unit is connected to the first current transformer unit and the second current transformer unit, and is used to generate a third voltage signal based on the first voltage signal and the second voltage signal.

[0008] The signal conversion unit is connected to the signal conditioning unit and is used to receive the third voltage signal and convert it into the secondary output current of the LLC converter.

[0009] Preferably, in one embodiment of the LLC converter current detection circuit of the present invention, the first current transformer unit includes a first current transformer coil and a first integrating circuit;

[0010] The first current inductor is coupled to the resonant inductor, and the same-name terminals of the first current inductor and the resonant inductor are arranged in the same direction.

[0011] The same-name terminal of the first current inductor is connected to the first terminal of the first integrating circuit, the opposite-name terminal of the first current inductor is connected to the second terminal of the first integrating circuit, and the third terminal of the first integrating circuit is used to output the first voltage signal.

[0012] Preferably, in one embodiment of the LLC converter current detection circuit of the present invention, the first integrating circuit includes a first resistor and a first capacitor;

[0013] The first end of the first resistor is connected to the same-name end of the first current inductor, and the first end of the first capacitor is connected to the opposite-name end of the first current inductor.

[0014] The second end of the first resistor is connected to the second end of the first capacitor and serves as the third end of the first integrating circuit.

[0015] Preferably, in one embodiment of the LLC converter current detection circuit of the present invention, the second current transformer unit includes a second current transformer coil and a second integrating circuit.

[0016] The second current inductor is coupled to the transformer core, and the same-name terminal of the second current inductor is opposite to the same-name terminal of the resonant inductor, or the same-name terminal of the second current inductor is opposite to the opposite-name terminal of the resonant inductor, or the opposite-name terminal of the second current inductor is opposite to the same-name terminal of the resonant inductor.

[0017] The same-name terminal of the second current inductor is connected to the first terminal of the second integrator circuit, the opposite-name terminal of the second current inductor is connected to the second terminal of the second integrator circuit, and the third terminal of the second integrator circuit is used to output the second voltage signal.

[0018] Preferably, in one embodiment of the LLC converter current detection circuit of the present invention, the second integrating circuit includes a second resistor and a second capacitor;

[0019] The first end of the second resistor is connected to the same-name end of the second current inductor, and the first end of the second capacitor is connected to the opposite-name end of the second current inductor.

[0020] The second end of the second resistor is connected to the second end of the second capacitor and serves as the third end of the second integrating circuit.

[0021] Preferably, in one embodiment of the LLC converter current detection circuit of the present invention, the signal conditioning unit includes a first signal conditioning submodule and a second signal conditioning submodule;

[0022] The first signal conditioning submodule is connected to the first current transformer unit and the second current transformer unit, and is used to generate an intermediate voltage signal based on the first voltage signal and the second voltage signal.

[0023] The second signal conditioning submodule is connected to the first signal conditioning submodule and is used to generate a third voltage signal based on the intermediate voltage signal.

[0024] Preferably, in one embodiment of the LLC converter current detection circuit of the present invention, the first signal conditioning submodule includes a third resistor and a fourth resistor;

[0025] The first end of the third resistor is connected to the first current transformer unit and is used to receive the first voltage signal; the first end of the fourth resistor is connected to the second current transformer unit and is used to receive the second voltage signal.

[0026] After the second end of the third resistor is connected to the second end of the fourth resistor, it is connected to the second signal conditioning submodule for sending the intermediate signal to the second signal conditioning submodule.

[0027] Preferably, in one embodiment of the LLC converter current detection circuit of the present invention, the resistance values ​​of the third resistor and the fourth resistor are the same.

[0028] Preferably, in one embodiment of the LLC converter current detection circuit of the present invention, the second signal conditioning submodule includes a voltage follower;

[0029] The voltage follower is connected to the first signal conditioning submodule and the signal conversion unit, and is used to receive the intermediate voltage signal and output the third voltage signal to the signal conversion unit, so that the signal conversion unit obtains the secondary output current of the LLC converter according to the third voltage signal.

[0030] Additionally, the present invention also provides a power supply, including the LLC converter current detection circuit as described above.

[0031] The LLC converter current detection circuit and power supply of the present invention have the following advantages: the circuit current detection can be achieved without affecting the performance of the original circuit and without complex fitting calculations. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0033] Figure 1 This is a logic block diagram of an embodiment of the LLC converter current detection circuit of the present invention;

[0034] Figure 2 This is a flowchart illustrating the operation of an embodiment of the LLC converter current detection circuit of the present invention;

[0035] Figure 3 This is a partial circuit schematic diagram of an embodiment of the LLC converter current detection circuit of the present invention;

[0036] Figure 4 This is a partial circuit diagram of another embodiment of the LLC converter current detection circuit of the present invention. Detailed Implementation

[0037] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0038] like Figure 1 As shown, an embodiment of the LLC converter current detection circuit of the present invention is illustrated. Figure 1 In the embodiment of the LLC converter current detection circuit of the present invention shown, the detection circuit includes: a first current transformer unit 110, a second current transformer unit 120, a signal conditioning unit 130, and a signal conversion unit 140; simultaneously as Figure 2 As shown, the first current inductor unit 110 is coupled to the resonant inductor in the LLC converter and is used to generate a first voltage signal based on the resonant current of the resonant inductor; the second current inductor unit 120 is coupled to the transformer core corresponding to the magnetizing inductor in the LLC converter and is used to generate a second voltage signal based on the magnetizing current of the magnetizing inductor; the signal conditioning unit 130 is connected to the first current inductor unit 110 and the second current inductor unit 120 and is used to generate a third voltage signal based on the first voltage signal and the second voltage signal; the signal conversion unit 140 is connected to the signal conditioning unit 130 and is used to receive the third voltage signal and convert it into the secondary output current of the LLC converter.

[0039] Specifically, based on the basic structure of the LLC converter, a first current transformer unit 110 is configured to work in conjunction with the resonant inductor in the LLC converter, enabling the first current transformer unit 110 to couple and sense the current flowing through the resonant inductor. This sensing process generates a corresponding first voltage signal, which is then input to the signal conditioning unit 130. A second current transformer unit 120 is configured to work in conjunction with the magnetizing inductor in the LLC converter, enabling the second current transformer unit 120 to couple and sense the current flowing through the magnetizing inductor. This sensing process generates a corresponding second voltage signal, which is then input to the signal conditioning unit 130. The signal conditioning unit 130 performs signal processing and conversion based on the received first and second voltage signals, ultimately outputting a third voltage signal. The signal conversion unit 140 receives this third voltage signal and performs signal processing and conversion to ultimately obtain the secondary-side output current during the operation of the LLC converter.

[0040] like Figure 3 As shown, in one embodiment, the first current transformer unit 110 includes a first current transformer coil CT1 and a first integrating circuit; the first current transformer coil is coupled to the resonant inductor, and the same-name terminal of the first current transformer coil and the same-name terminal of the resonant inductor are arranged in the same direction; the same-name terminal of the first current transformer coil is connected to the first terminal of the first integrating circuit, the opposite-name terminal of the first current transformer coil is connected to the second terminal of the first integrating circuit, and the third terminal of the first integrating circuit is used to output the first voltage signal.

[0041] Specifically, in the first current transformer unit 110, the current of the resonant inductor in the LLC converter is coupled through the first current transformer coil to obtain a coupling signal, and the coupling signal is processed by the first integrator circuit to finally obtain the first voltage signal.

[0042] In one embodiment, the first integrating circuit includes a first resistor and a first capacitor; the first end of the first resistor is connected to the same-name terminal of the first current inductor, and the first end of the first capacitor is connected to the opposite-name terminal of the first current inductor; the second end of the first resistor and the second end of the first capacitor are connected to each other and serve as the third end of the first integrating circuit. Specifically, the first resistor and the first capacitor form an RC integrating circuit to integrate the coupled signal of the first current inductor to obtain an output voltage, i.e., a first voltage signal. In a specific embodiment, the first resistor includes resistor R1, and the first capacitor includes capacitor C1. The first end of resistor R1 is connected to the same-name terminal of the first current inductor, the first end of capacitor C1 is connected to the opposite-name terminal of the first current inductor, and the second end of resistor R1 is connected to the second end of capacitor C1 to form a series connection. The series connection node of resistor R1 and capacitor C1 is used to output the first voltage signal. The opposite-name terminal of the first current inductor is grounded.

[0043] In one specific embodiment, a first voltage signal can be obtained based on the first current inductance unit 110. as follows:

[0044]

[0045] in, This is the inductance value of the resonant inductor. This is the resistance value of the first resistor. This is the capacitance value of the first capacitor. The turns ratio of the resonant inductor to the first current-transformed coil is given. This is the resonant current of the resonant inductor.

[0046] like Figure 4 As shown, in one embodiment, the second current transformer unit 120 includes a second current transformer coil CT2 and a second integrating circuit; the second current transformer coil is coupled to the transformer core, and the opposite-named terminal of the second current transformer coil is disposed opposite to the same-named terminal of the resonant inductor; the same-named terminal of the second current transformer coil is connected to the first terminal of the second integrating circuit, the opposite-named terminal of the second current transformer coil is connected to the second terminal of the second integrating circuit, and the third terminal of the second integrating circuit is used to output the second voltage signal.

[0047] Specifically, in the second current transformer unit 120, the current of the excitation inductor in the LLC converter is coupled through the second current transformer coil CT2 to obtain a coupling signal, and the coupling signal is processed by the second integrator circuit to finally obtain the second voltage signal.

[0048] Additionally, such as Figure 2 The diagram only shows the way the opposite-named terminals of the second current inductor CT2 are connected to the same-named terminals of the resonant inductor, based on... Figure 2 The direction of the second current inductor CT2 can be adjusted so that the same-name terminal of the second current inductor CT2 is opposite to the opposite-name terminal of the resonant inductor, or the same-name terminal of the second current inductor CT2 is opposite to the same-name terminal of the resonant inductor.

[0049] In one embodiment, the second integrating circuit includes a second resistor and a second capacitor. The first end of the second resistor is connected to the same-name terminal of the second current inductor, and the first end of the second capacitor is connected to the opposite-name terminal of the second current inductor. The second end of the second resistor and the second end of the second capacitor are connected to each other and serve as the third end of the second integrating circuit. Specifically, the second resistor and the second capacitor form an RC integrating circuit to integrate the coupled signal of the second current inductor to obtain an output voltage, i.e., a second voltage signal. In a specific embodiment, the second resistor includes resistor R2, and the second capacitor includes capacitor C2. The first end of resistor R2 is connected to the same-name terminal of the second current inductor, the first end of capacitor C2 is connected to the opposite-name terminal of the second current inductor, and the second end of resistor R2 is connected to the second end of capacitor C2 to form a series connection. The series connection node of resistor R2 and capacitor C2 is used to output the second voltage signal. The opposite-name terminal of the second current inductor is grounded.

[0050] In one specific embodiment, based on Figure 2 As shown, the second current transformer unit 120 can obtain the second voltage signal. as follows:

[0051]

[0052] in, The inductance value is the magnetizing inductance. This is the resistance value of the second resistor. This is the capacitance value of the second capacitor. This represents the turns ratio of the magnetizing inductor to the second current inductor. This is the resonant current of the magnetizing inductor, which can also be understood as the primary winding of a transformer.

[0053] like Figure 3 As shown, in one embodiment, the signal conditioning unit 130 includes a first signal conditioning submodule 131 and a second signal conditioning submodule 132; the first signal conditioning submodule 131 is connected to the first current transformer unit 110 and the second current transformer unit 120, and is used to generate an intermediate voltage signal based on the first voltage signal and the second voltage signal; the second signal conditioning submodule 132 is connected to the first signal conditioning submodule 131, and is used to generate a third voltage signal based on the intermediate voltage signal.

[0054] Specifically, in the signal conditioning unit 130, the first signal conditioning submodule 131 performs preliminary conditioning based on the first voltage signal and the second voltage signal to obtain an intermediate voltage signal. The second signal conditioning submodule 132 processes the obtained intermediate voltage signal to finally obtain the corresponding third voltage signal.

[0055] In one embodiment, the first signal conditioning submodule 131 includes a third resistor and a fourth resistor; the first end of the third resistor is connected to the first current transformer unit 110 for receiving the first voltage signal; the first end of the fourth resistor is connected to the second current transformer unit 120 for receiving the second voltage signal; the second end of the third resistor and the second end of the fourth resistor are connected to each other and then connected to the second signal conditioning submodule 132 for sending an intermediate signal to the second signal conditioning submodule 132.

[0056] Specifically, a voltage divider circuit is formed by the third and fourth resistors to divide the first and second voltage signals, ultimately obtaining the divided voltage signal, i.e., the intermediate voltage signal. In one specific embodiment, the third resistor includes resistor R3, and the fourth resistor includes resistor R4. Based on resistors R3 and R4, the intermediate voltage signal can be obtained at the connection point of resistors R3 and R4. As shown in the following formula:

[0057]

[0058] in, This is the first voltage signal. This is the second voltage signal. It is obtained by subtracting the resonant current and the excitation current to get the voltage value representing the output current. In one embodiment, Figure 4 The diagram shows the relationship between the resonant current and the excitation current of the converter under a certain operating condition.

[0059] In one embodiment, the orientation of the second current transformer unit 120 can also be adjusted so that, after obtaining the second voltage signal, the intermediate voltage signal can be adjusted. The calculation formula is used to obtain the corresponding intermediate voltage signal. For example, the direction of the second current inductor coil CT2 in the second current inductor unit 120 can be adjusted so that the same-name terminal of the second current inductor coil CT2 is opposite to the opposite-name terminal of the resonant inductor, or the same-name terminal of the second current inductor coil CT2 is opposite to the same-name terminal of the resonant inductor.

[0060] In one specific embodiment, the third resistor has the same resistance value as the fourth resistor.

[0061]

[0062] Simultaneously set:

[0063]

[0064] The final intermediate voltage signal satisfies:

[0065]

[0066] in, This represents the real-time value of the secondary-side output current of the LLC converter. This embodiment directly obtains the voltage value representing the secondary-side output current using simple circuit parameter matching. The entire process requires no complex calculations and eliminates the need for a primary-side series current sampling circuit, reducing circuit losses and improving the power density of the LLC converter.

[0067] In one embodiment, the second signal conditioning submodule 132 includes a voltage follower; the voltage follower is connected to the first signal conditioning submodule 131 and the signal conversion unit 140, and is used to receive the intermediate voltage signal and output the third voltage signal to the signal conversion unit 140, so that the signal conversion unit 140 obtains the secondary output current of the LLC converter based on the third voltage signal. Specifically, the intermediate voltage signal is conditioned by the voltage follower. It can be understood that the process of conditioning the intermediate voltage signal by the voltage follower does not affect the magnitude of the intermediate voltage signal, that is, the magnitude of the final obtained third voltage signal remains the same. Finally, the signal conversion unit 140 obtains the current at the secondary output terminal based on the conditioned intermediate voltage signal. It can be:

[0068]

[0069] in, for The value is taken as a function of time to ultimately obtain the current at the secondary output terminal. In one specific embodiment, the signal conversion unit 140 may include an MCU chip and its peripheral circuitry, or it may be a peripheral device containing a controller.

[0070] Furthermore, a power supply according to the present invention includes the LLC converter current detection circuit as described above. That is, in the power supply, the power input is converted by an LLC converter to provide a power output at the power output terminal, and the output current at the power output terminal is detected by the LLC converter current detection circuit to obtain the power supply's output current. This process allows for the detection of the power supply's operation, facilitating control of the power supply's operation as needed.

[0071] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A current detection circuit for an LLC converter, characterized in that, include: The system comprises a first current transformer unit, a second current transformer unit, a signal conditioning unit, and a signal conversion unit. The first current transformer unit is coupled to the resonant inductor in the LLC converter and is used to generate a first voltage signal based on the resonant current of the resonant inductor. The second current transformer unit is coupled to the transformer core corresponding to the magnetizing inductor in the LLC converter, and is used to generate a second voltage signal based on the magnetizing current of the magnetizing inductor. The signal conditioning unit is connected to the first current transformer unit and the second current transformer unit, and is used to generate a third voltage signal based on the first voltage signal and the second voltage signal. The signal conversion unit is connected to the signal conditioning unit and is used to receive the third voltage signal and convert it into the secondary output current of the LLC converter.

2. The LLC converter current detection circuit according to claim 1, characterized in that, The first current transformer unit includes a first current transformer coil and a first integrating circuit; The first current inductor is coupled to the resonant inductor, and the same-name terminals of the first current inductor and the resonant inductor are arranged in the same direction. The same-name terminal of the first current inductor is connected to the first terminal of the first integrating circuit, the opposite-name terminal of the first current inductor is connected to the second terminal of the first integrating circuit, and the third terminal of the first integrating circuit is used to output the first voltage signal.

3. The LLC converter current detection circuit according to claim 2, characterized in that, The first integrating circuit includes a first resistor and a first capacitor; The first end of the first resistor is connected to the same-name end of the first current inductor, and the first end of the first capacitor is connected to the opposite-name end of the first current inductor. The second end of the first resistor is connected to the second end of the first capacitor and serves as the third end of the first integrating circuit.

4. The LLC converter current detection circuit according to claim 2, characterized in that, The second current transformer unit includes a second current transformer coil and a second integrating circuit; The second current inductor is coupled to the transformer core, and the same-name terminal of the second current inductor is opposite to the same-name terminal of the resonant inductor, or the same-name terminal of the second current inductor is opposite to the opposite-name terminal of the resonant inductor, or the opposite-name terminal of the second current inductor is opposite to the same-name terminal of the resonant inductor. The same-name terminal of the second current inductor is connected to the first terminal of the second integrator circuit, the opposite-name terminal of the second current inductor is connected to the second terminal of the second integrator circuit, and the third terminal of the second integrator circuit is used to output the second voltage signal.

5. The LLC converter current detection circuit according to claim 4, characterized in that, The second integrating circuit includes a second resistor and a second capacitor; The first end of the second resistor is connected to the same-name end of the second current inductor, and the first end of the second capacitor is connected to the opposite-name end of the second current inductor. The second end of the second resistor is connected to the second end of the second capacitor and serves as the third end of the second integrating circuit.

6. The LLC converter current detection circuit according to claim 5, characterized in that, The signal conditioning unit includes a first signal conditioning submodule and a second signal conditioning submodule; The first signal conditioning submodule is connected to the first current transformer unit and the second current transformer unit, and is used to generate an intermediate voltage signal based on the first voltage signal and the second voltage signal. The second signal conditioning submodule is connected to the first signal conditioning submodule and is used to generate a third voltage signal based on the intermediate voltage signal.

7. The LLC converter current detection circuit according to claim 6, characterized in that, The first signal conditioning submodule includes a third resistor and a fourth resistor; The first end of the third resistor is connected to the first current transformer unit and is used to receive the first voltage signal; the first end of the fourth resistor is connected to the second current transformer unit and is used to receive the second voltage signal. After the second end of the third resistor is connected to the second end of the fourth resistor, it is connected to the second signal conditioning submodule for sending the intermediate signal to the second signal conditioning submodule.

8. The LLC converter current detection circuit according to claim 7, characterized in that, The third resistor has the same resistance value as the fourth resistor.

9. The LLC converter current detection circuit according to claim 6, characterized in that, The second signal conditioning submodule includes a voltage follower; The voltage follower is connected to the first signal conditioning submodule and the signal conversion unit, and is used to receive the intermediate voltage signal and output the third voltage signal to the signal conversion unit, so that the signal conversion unit obtains the secondary output current of the LLC converter according to the third voltage signal.

10. A power supply, characterized in that, Includes the LLC converter current detection circuit as described in any one of claims 1-9.

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