LLC output ripple voltage detection control method and control circuit

Abstract

The invention discloses an LLC output ripple voltage detection control method and control circuit, and the method comprises the steps: obtaining a current input voltage of an LLC circuit through a filter circuit, and obtaining a corresponding current filter circuit output voltage after the current input voltage is input; the subtraction circuit compares the current input voltage with the current filtering output voltage to obtain the current ripple voltage; the repetitive controller processes the current ripple voltage to obtain a current control output voltage; and the PID controller obtains a current output comparison result, sequentially performs amplitude limiting and pulse frequency modulation on the current output comparison result and a current comparison result of the current control output voltage, and inputs the current output comparison result and the current comparison result to a control object connected with the LLC output ripple voltage detection control circuit. According to the embodiment of the invention, the alternating current ripple voltage in the LLC circuit is extracted through the filter circuit and the subtraction circuit, the sampling precision is improved, the ripple voltage is suppressed by adopting repetitive control after the ripple voltage is extracted, and the influence of the ripple voltage on load power supply is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply control, and in particular to an LLC output ripple voltage detection control method and a control circuit. Background Art

[0002] The front-stage bus voltage of the LLC charging module (a resonant network consisting of two inductors and one capacitor) is generally provided by PFC (the full name is Power Factor Correction). The PFC bus voltage will introduce power frequency fluctuations, resulting in power frequency ripples in the LLC output voltage. The ripple voltage corresponding to the power frequency ripple affects the load power supply. For example, the battery charging at the back end may affect the battery life. The current common method for controlling ripple voltage is to increase the loop low-frequency gain or increase the bus or LLC filter capacitor. However, due to the wide output voltage range of the LLC, the ripple voltage sampling is distorted, the loop control suppression effect is limited, and the increase in bus or LLC filter capacitors will lead to increased costs. Summary of the invention

[0003] The embodiment of the present invention provides an LLC output ripple voltage detection control method and a control circuit, aiming to solve the problem that when the front-stage bus voltage of the LLC charging module is provided by PFC in the prior art, in order to suppress the ripple voltage corresponding to the power frequency ripple, the loop low-frequency gain is increased, or the bus or LLC filter capacitor is increased. However, due to the wide LLC output voltage range, the ripple voltage sampling is distorted and the loop control suppression effect is limited.

[0004] In a first aspect, an embodiment of the present invention provides an LLC output ripple voltage detection control method, which is applied to an LLC output ripple voltage detection control circuit, wherein the LLC output ripple voltage detection control circuit comprises a filter circuit, a subtraction circuit, a repetitive controller and a PID controller, wherein the input end of the filter circuit is connected to the output end of the LLC circuit, the output end of the filter circuit is connected to the second input end of the subtraction circuit, the output end of the LLC circuit is also connected to the first input end of the subtraction circuit, and the output end of the subtraction circuit is connected to the PID controller through the repetitive controller; the LLC output ripple voltage detection control method comprises: The filter circuit obtains a current input voltage of the LLC circuit, and obtains a current filter circuit output voltage corresponding to the current input voltage; The subtraction circuit compares the current input voltage with the current filtered output voltage to obtain a current ripple voltage; The repetitive controller controls the current ripple voltage to obtain a current controlled output voltage; The PID controller obtains a current output comparison result, and sequentially subjects the current output comparison result and the current comparison result of the current control output voltage to amplitude limiting and pulse frequency modulation, and inputs the result to a control object connected to the LLC output ripple voltage detection control circuit.

[0005] In a second aspect, an embodiment of the present invention further provides an LLC output ripple voltage detection control circuit, which includes a filter circuit, a subtraction circuit, a repetitive controller and a PID controller, wherein the input end of the filter circuit is connected to the output end of the LLC circuit, the output end of the filter circuit is connected to the second input end of the subtraction circuit, the output end of the LLC circuit is also connected to the first input end of the subtraction circuit, and the output end of the subtraction circuit is connected to the PID controller through the repetitive controller; The filter circuit is used to obtain the current input voltage of the LLC circuit, and obtain the current filter circuit output voltage corresponding to the current input voltage; The subtraction circuit is used to compare the current input voltage with the current filtered output voltage to obtain a current ripple voltage; The repetitive controller is used to control the current ripple voltage to obtain a current controlled output voltage; The PID controller is used to obtain a current output comparison result, and subject the current output comparison result and the current comparison result of the current control output voltage to limiting and pulse frequency modulation in sequence and input them into a control object connected to the LLC output ripple voltage detection control circuit.

[0006] The embodiment of the present invention provides an LLC output ripple voltage detection control method and control circuit, the method includes: the filter circuit obtains the current input voltage of the LLC circuit, and obtains the current filter circuit output voltage corresponding to the current input voltage; the subtraction circuit compares the current input voltage with the current filter output voltage to obtain the current ripple voltage; the repetitive controller controls and processes the current ripple voltage to obtain the current control output voltage; the PID controller obtains the current output comparison result, and the current comparison result of the current output comparison result and the current control output voltage are subjected to amplitude limiting and pulse frequency modulation in sequence and input to the control object connected to the LLC output ripple voltage detection control circuit. The embodiment of the present invention extracts the AC ripple voltage in the LLC circuit through the filter circuit and the subtraction circuit, improves the sampling accuracy, and uses repetitive control to suppress the ripple voltage after extracting the ripple voltage, thereby reducing the influence of the ripple voltage on the load power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0008] Figure 1 A schematic flow chart of an LLC output ripple voltage detection and control method provided by an embodiment of the present invention; Figure 2 A schematic block diagram of an LLC output ripple voltage detection control circuit provided by an embodiment of the present invention; Figure 3 A schematic diagram of a sub-process of an LLC output ripple voltage detection and control method provided by an embodiment of the present invention; Figure 4 Another schematic block diagram of an LLC output ripple voltage detection control circuit provided by an embodiment of the present invention; Figure 5 A schematic diagram of the circuit structure of a filter circuit and a subtraction circuit in an LLC output ripple voltage detection control circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0009] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0010] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0011] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0012] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0013] See also Figure 1 , which is a flow chart of the LLC output ripple voltage detection control method provided by an embodiment of the present invention. The LLC output ripple voltage detection control method is applied to the LLC output ripple voltage detection control circuit, such as Figure 2 As shown, the LLC output ripple voltage detection control circuit includes a filter circuit 10, a subtraction circuit 20, a repetitive controller 30 and a PID controller 40. The input end of the filter circuit 10 is connected to the output end of the LLC circuit 50, the output end of the filter circuit 10 is connected to the second input end of the subtraction circuit 20, the output end of the LLC circuit 50 is also connected to the first input end of the subtraction circuit 20, and the output end of the subtraction circuit 20 is connected to the PID controller 40 through the repetitive controller 30. Figure 1 As shown, the LLC output ripple voltage detection and control method includes steps S110 to S140.

[0014] S110, the filter circuit obtains a current input voltage of the LLC circuit, and obtains a current filter circuit output voltage corresponding to the current input voltage.

[0015] In this embodiment, the front-stage bus voltage of the LLC circuit is generally provided by a PFC device (i.e., a power factor correction device). If the output voltage of the LLC circuit is directly used to power the load, the output voltage of the LLC circuit will have a ripple voltage and affect the power supply to the load. In this application, in order to eliminate the influence of the ripple voltage in the output voltage of the LLC circuit, the current input voltage of the LLC circuit (such as V out ) to filter and obtain the current filter circuit output voltage (such as V' out ). Through the above filtering circuit, the ripple voltage in the output voltage of the LLC circuit can be filtered.

[0016] S120. The subtraction circuit compares the current input voltage with the current filtered output voltage to obtain a current ripple voltage.

[0017] In this embodiment, since one input end of the subtraction circuit is connected to the output end of the filter circuit and the other input end of the subtraction circuit is connected to the output end of the LLC circuit, the current ripple voltage (such as V'') can be obtained by comparing the current input voltage output from the output end of the LLC circuit with the current filtered output voltage output from the output end of the filter circuit. out ). Through the above method, the ripple voltage that has been filtered out by the filter circuit can be extracted, and the sampling accuracy is improved.

[0018] S130, the repetitive controller controls the current ripple voltage to obtain a current controlled output voltage.

[0019] In this embodiment, in order to achieve accurate suppression of the ripple voltage, a repetitive controller can be used to control the current ripple voltage to obtain the current control output voltage. Among them, the repetitive controller is a controller used in the control field to process periodic signal interference or track periodic reference signals. It refers to the internal model principle and embeds an internal model with the same period as the external periodic signal inside the controller, so that the periodic signal can be tracked or suppressed with high precision.

[0020] In one embodiment, step S130 includes: The repetitive control model in the repetitive controller receives the input ripple signal corresponding to the current ripple voltage and performs control processing to obtain the current controlled output voltage corresponding to the current ripple voltage.

[0021] In this embodiment, the repetitive control model in the repetitive controller includes at least a delay link (for example, for a periodic interference with a frequency of 50 Hz, the delay time of the delay link is correspondingly set to 20 ms), a compensator (which can be a simple PID controller) and a filter (for example, a combination of a low-pass filter and a notch filter). The repetitive control model in the repetitive controller can be used to extract the current ripple voltage V'' output by the subtraction circuit. out The input ripple signal in the control process is finally obtained to obtain the current control output voltage corresponding to the current ripple voltage (such as V q ). Moreover, the use of a repetitive controller can continuously accumulate and adjust the control signal over multiple cycles, thereby achieving high-precision processing of periodic signals.

[0022] S140, the PID controller obtains a current output comparison result, and sequentially subjects the current output comparison result and the current comparison result of the current control output voltage to amplitude limiting and pulse frequency modulation, and inputs the result to a control object connected to the LLC output ripple voltage detection control circuit.

[0023] In this embodiment, when the current control output voltage is determined by the repetitive controller, it can be regarded as the voltage corresponding to the precise tracking signal of the ripple voltage. At this time, the PID controller can first obtain the current output comparison result (such as comparing the preset reference voltage with the current detection output voltage corresponding to the control object, if the preset reference voltage is recorded as V ref , and the current detection output voltage corresponding to the control object is recorded as V t , then the current output comparison result = V ref -V t), and then compare the current output comparison result with the current control output voltage V q The current comparison result (i.e. V ref -V t -V q ) is processed by amplitude limiting and pulse frequency modulation in sequence, and finally input to the control object connected to the LLC output ripple voltage detection control circuit. At this time, the output voltage detected by the control object will also be fed back to the input end of the PID controller and continuously compared with the preset reference voltage, thereby dynamically realizing the suppression of the ripple voltage.

[0024] In one embodiment, if Figure 3 As shown, the step S140 of obtaining the current output comparison result includes: S141, obtaining a preset reference voltage and a current detected output voltage corresponding to the control object; S142: Obtain a difference between the preset reference voltage and the current detection output voltage, and use the difference as the current output comparison result.

[0025] In this embodiment, a first comparator can be connected before the input end of the PID controller to compare the preset reference voltage and the current detection output voltage corresponding to the control object. When the first comparator obtains the difference between the preset reference voltage and the current detection output voltage, it can be used as the input of the PID controller to accurately suppress the ripple voltage.

[0026] In one embodiment, if Figure 3 As shown, in step S140, the current output comparison result and the current comparison result of the current control output voltage are sequentially subjected to amplitude limiting and pulse frequency modulation and input to the control object connected to the LLC output ripple voltage detection control circuit, including: S143, obtaining a current comparison result between the current output comparison result and the current control output voltage; S144, performing voltage limiting processing on the current comparison result through a voltage limiting circuit to obtain a current voltage limiting result; S145, performing pulse frequency modulation processing on the current voltage limiting result through a pulse frequency modulation circuit to obtain a current regulated output voltage, and inputting the current regulated output voltage to the control object.

[0027] In this embodiment, a second comparator can be connected after the output end of the PID controller and before the voltage limiting circuit to compare the current output comparison result with the current control output voltage to obtain the current comparison result. The voltage corresponding to the current comparison result obtained has suppressed the ripple voltage. At this time, the current comparison result is subjected to voltage limiting processing by the voltage limiting circuit in turn to obtain the current voltage limiting result. Finally, the current voltage limiting result is subjected to pulse frequency modulation processing by the pulse frequency modulation circuit to obtain the current regulated output voltage. Among them, the voltage limiting circuit is used to limit the input voltage (i.e., the above-mentioned current comparison result) within a specific range to ensure that the current voltage limiting result does not exceed the preset upper and lower voltage limits. Specifically, a diode limiting circuit, a voltage regulator limiting circuit, etc. can be used. The pulse frequency modulation circuit is used to change the frequency of the output pulse signal according to the amplitude of the input signal, that is, the pulse frequency modulation processing is performed according to the current voltage limiting result to obtain the current regulated output voltage, and the pulse frequency modulation circuit at least includes a comparator, an oscillator, and an integrator. After the above voltage limiting and pulse frequency modulation processing, the currently adjusted output voltage can be input to the control object (such as batteries and other circuits as loads). After obtaining the voltage input, the control object can also detect its own current detection output voltage, which is then fed back to the first comparator for comparison with the preset reference voltage to perform the next round of PID control adjustment. In specific implementation, the LLC output ripple voltage detection control method and its corresponding LLC output ripple voltage detection control circuit can also be used in a DC-DC circuit module (i.e., a direct current-to-direct current circuit module).

[0028] It can be seen that the embodiment of the method extracts the AC ripple voltage in the LLC circuit through a filtering circuit and a subtraction circuit to improve the sampling accuracy. After the ripple voltage is extracted, the ripple voltage is suppressed by repeated control to reduce the impact of the ripple voltage on the load power supply.

[0029] The present application also provides an LLC output ripple voltage detection control circuit, Figure 4 FIG. 1 is a schematic block diagram of an LLC output ripple voltage detection control circuit provided by an embodiment of the present invention. Figure 2 and Figure 4As shown, corresponding to the above LLC output ripple voltage detection control method, the present invention also provides an LLC output ripple voltage detection control circuit 100. The LLC output ripple voltage detection control device 100 includes: a filter circuit 10, a subtraction circuit 20, a repetitive controller 30 and a PID controller 40, the input end of the filter circuit 10 is connected to the output end of the LLC circuit 50, the output end of the filter circuit 10 is connected to the second input end of the subtraction circuit 20, the output end of the LLC circuit 50 is also connected to the first input end of the subtraction circuit 20, and the output end of the subtraction circuit 20 is connected to the PID controller 40 through the repetitive controller 30.

[0030] The filter circuit 10 is used to obtain the current input voltage of the LLC circuit, and obtain the current filter circuit output voltage corresponding to the current input voltage.

[0031] In this embodiment, the front bus voltage of the LLC circuit is generally provided by a PFC device (i.e., a power factor correction device). If the load is powered directly by the output voltage of the LLC circuit, the output voltage of the LLC circuit will have a ripple voltage and affect the power supply to the load. In this application, in order to eliminate the influence of the ripple voltage in the output voltage of the LLC circuit, the current input voltage of the LLC circuit (such as V out ) to filter and obtain the current filter circuit output voltage (such as V' out ). Through the above filtering circuit, the ripple voltage in the output voltage of the LLC circuit can be filtered.

[0032] In one embodiment, if Figure 4 and Figure 5 As shown, the filtering circuit 10 includes a first resistor R1, a second resistor R2, a third resistor R3, a first capacitor C1 and a second capacitor C2; the first end of the first resistor R1 is connected to the output end of the LLC circuit 50; the first end of the first capacitor C1 is connected to the second end of the first resistor R1, and the second end of the first capacitor C1 is grounded; the first end of the second resistor R2 is connected to the second end of the first resistor R1; the first end of the second capacitor C2 is connected to the second end of the second resistor R2, and the second end of the second capacitor C2 is grounded; the first end of the third resistor R3 is connected to the second end of the second resistor R2, and the second end of the third resistor R3 is connected to the subtraction circuit 20.

[0033] In this embodiment, by using the filter circuit 10 of the above circuit structure, that is, by using the filter circuit composed of the first resistor R1, the second resistor R2, the third resistor R3, the first capacitor C1 and the second capacitor C2, the current input voltage (such as Vout ) to filter and obtain the current filter circuit output voltage (such as V' out ), thereby effectively filtering the ripple voltage.

[0034] The subtraction circuit 20 is used to compare the current input voltage with the current filtered output voltage to obtain a current ripple voltage.

[0035] In this embodiment, since one input end of the subtraction circuit is connected to the output end of the filter circuit and the other input end of the subtraction circuit is connected to the output end of the LLC circuit, the current ripple voltage (such as V'') can be obtained by comparing the current input voltage output from the output end of the LLC circuit with the current filtered output voltage output from the output end of the filter circuit. out ). Through the above method, the ripple voltage that has been filtered out by the filter circuit can be extracted, and the sampling accuracy is improved.

[0036] In one embodiment, if Figure 4 and Figure 5 As shown, the subtraction circuit 20 includes a comparator COMP, a fourth resistor R4, a fifth resistor R5, a third capacitor C3 and a fourth capacitor C4; the negative input terminal of the comparator COMP is connected to the second end of the third resistor R3, and is also connected to the first end of the fourth resistor R4; the second end of the fourth resistor R4 is connected to the output terminal of the comparator COMP; the first end of the third capacitor C3 is connected to the negative input terminal of the comparator COMP, and the second end of the third capacitor C3 is connected to the output terminal of the comparator COMP; the first end of the fifth resistor R5 is grounded, and the second end of the fifth resistor R5 is connected to the positive input terminal of the comparator COMP; the fourth capacitor C4 is connected in parallel with the fifth resistor R5.

[0037] In this embodiment, by adopting the subtraction circuit 20 of the above circuit structure, that is, by adopting the subtraction circuit 20 composed of the comparator COMP, the fourth resistor R4, the fifth resistor R5, the third capacitor C3 and the fourth capacitor C4, the comparator COMP can compare the current input voltage output by the output end of the LLC circuit with the current filtered output voltage output by the output end of the filter circuit, so as to obtain the current ripple voltage V'' out. In order to improve the accuracy of obtaining the current input voltage, a sixth resistor R6 and a seventh resistor R7 may be connected in series between the positive input terminal of the comparator COMP and the output terminal of the LLC circuit 50. At the same time, in order to improve the stability of the circuit, a clamping circuit may be connected to the output terminal of the comparator COMP, which can "clamp" the signal level at a specific DC level so that a certain part of the signal (positive half cycle or negative half cycle) will not exceed or fall below this specific level, so as to achieve the purpose of protecting circuit components or changing the DC level of the signal.

[0038] The repetitive controller 30 is used to control the current ripple voltage to obtain a current controlled output voltage.

[0039] In this embodiment, in order to achieve accurate suppression of the ripple voltage, a repetitive controller can be used to control the current ripple voltage to obtain the current control output voltage. Among them, the repetitive controller is a controller used in the control field to process periodic signal interference or track periodic reference signals. It refers to the internal model principle and embeds an internal model with the same period as the external periodic signal inside the controller, so that the periodic signal can be tracked or suppressed with high precision.

[0040] In one embodiment, the repetitive controller 30 is specifically used for: The repetitive control model in the repetitive controller receives the input ripple signal corresponding to the current ripple voltage and performs control processing to obtain the current controlled output voltage corresponding to the current ripple voltage.

[0041] In this embodiment, the repetitive control model in the repetitive controller includes at least a delay link (for example, for a periodic interference with a frequency of 50 Hz, the delay time of the delay link is correspondingly set to 20 ms), a compensator (which can be a simple PID controller) and a filter (for example, a combination of a low-pass filter and a notch filter). The repetitive control model in the repetitive controller can be used to extract the current ripple voltage V'' output by the subtraction circuit. out The input ripple signal in the control process is finally obtained to obtain the current control output voltage corresponding to the current ripple voltage (such as V q ). Moreover, the use of a repetitive controller can continuously accumulate and adjust the control signal over multiple cycles, thereby achieving high-precision processing of periodic signals.

[0042] The PID controller 40 is used to obtain a current output comparison result, and subject the current output comparison result and the current comparison result of the current control output voltage to amplitude limiting and pulse frequency modulation in sequence, and input them into a control object connected to the LLC output ripple voltage detection control circuit.

[0043] In this embodiment, when the current control output voltage is determined by the repetitive controller, it can be regarded as the voltage corresponding to the precise tracking signal of the ripple voltage. At this time, the PID controller can first obtain the current output comparison result (such as comparing the preset reference voltage with the current detection output voltage corresponding to the control object, if the preset reference voltage is recorded as V ref , and the current detection output voltage corresponding to the control object is recorded as V t , then the current output comparison result = V ref -V t ), and then compare the current output comparison result with the current control output voltage V q The current comparison result (i.e. V ref -V t -V q ) is processed by amplitude limiting and pulse frequency modulation in sequence, and finally input to the control object connected to the LLC output ripple voltage detection control circuit. At this time, the output voltage detected by the control object will also be fed back to the input end of the PID controller and continuously compared with the preset reference voltage, thereby dynamically realizing the suppression of the ripple voltage.

[0044] In one embodiment, obtaining the current output comparison result includes: Acquire a preset reference voltage and a current detected output voltage corresponding to the control object; A difference between the preset reference voltage and the current detection output voltage is obtained and used as the current output comparison result.

[0045] In this embodiment, a first comparator can be connected before the input end of the PID controller to compare the preset reference voltage and the current detection output voltage corresponding to the control object. When the first comparator obtains the difference between the preset reference voltage and the current detection output voltage, it can be used as the input of the PID controller to accurately suppress the ripple voltage.

[0046] In one embodiment, the current comparison result of the current output and the current comparison result of the current control output voltage are sequentially subjected to amplitude limiting and pulse frequency modulation and input to a control object connected to the LLC output ripple voltage detection control circuit, including: Obtaining a current comparison result between the current output comparison result and the current control output voltage; The current comparison result is subjected to voltage limiting processing by a voltage limiting circuit to obtain a current voltage limiting result; The current voltage limiting result is subjected to pulse frequency modulation processing by a pulse frequency modulation circuit to obtain a current regulated output voltage, and the current regulated output voltage is input to the control object.

[0047] In this embodiment, a second comparator can be connected after the output end of the PID controller and before the voltage limiting circuit to compare the current output comparison result with the current control output voltage to obtain the current comparison result. The voltage corresponding to the current comparison result obtained has suppressed the ripple voltage. At this time, the current comparison result is subjected to voltage limiting processing by the voltage limiting circuit in turn to obtain the current voltage limiting result. Finally, the current voltage limiting result is subjected to pulse frequency modulation processing by the pulse frequency modulation circuit to obtain the current regulated output voltage. Among them, the voltage limiting circuit is used to limit the input voltage (i.e., the above-mentioned current comparison result) within a specific range to ensure that the current voltage limiting result does not exceed the preset upper and lower voltage limits. Specifically, a diode limiting circuit, a voltage regulator limiting circuit, etc. can be used. The pulse frequency modulation circuit is used to change the frequency of the output pulse signal according to the amplitude of the input signal, that is, the pulse frequency modulation processing is performed according to the current voltage limiting result to obtain the current regulated output voltage, and the pulse frequency modulation circuit at least includes a comparator, an oscillator, and an integrator. After the voltage limiting and pulse frequency modulation processing, the current regulated output voltage can be input to the control object (such as the battery and other circuits as loads). After receiving the voltage input, the control object can also detect its own current detection output voltage, which is then fed back to the first comparator for comparison with the preset reference voltage to perform the next round of PID control adjustment.

[0048] It can be seen that the embodiment of implementing the circuit extracts the AC ripple voltage in the LLC circuit through the filtering circuit and the subtraction circuit, improves the sampling accuracy, and uses repeated control to suppress the ripple voltage after extracting the ripple voltage, thereby reducing the impact of the ripple voltage on the load power supply.

[0049] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0050] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of each unit is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0051] The steps in the method of the embodiment of the present invention can be adjusted in order, combined and deleted according to actual needs. The units in the device of the embodiment of the present invention can be combined, divided and deleted according to actual needs. In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0052] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, terminal, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention.

[0053] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A LLC output ripple voltage detection control method, applied to an LLC output ripple voltage detection control circuit, characterized in that: The LLC output ripple voltage detection control circuit comprises a filter circuit, a subtraction circuit, a repetitive controller and a PID controller, wherein the input end of the filter circuit is connected to the output end of the LLC circuit, the output end of the filter circuit is connected to the second input end of the subtraction circuit, the output end of the LLC circuit is also connected to the first input end of the subtraction circuit, and the output end of the subtraction circuit is connected to the PID controller via the repetitive controller; The LLC output ripple voltage detection and control method comprises: The filter circuit obtains a current input voltage of the LLC circuit, and obtains a current filter circuit output voltage corresponding to the current input voltage; The subtraction circuit compares the current input voltage with the current filtered output voltage to obtain a current ripple voltage; The repetitive controller controls the current ripple voltage to obtain a current controlled output voltage; The PID controller obtains a current output comparison result, and sequentially subjects the current output comparison result and the current comparison result of the current control output voltage to amplitude limiting and pulse frequency modulation, and inputs the result to a control object connected to the LLC output ripple voltage detection control circuit.

2. The method according to claim 1, characterized in that The repetitive controller controls the current ripple voltage to obtain a current controlled output voltage, including: The repetitive control model in the repetitive controller receives the input ripple signal corresponding to the current ripple voltage and performs control processing to obtain the current controlled output voltage corresponding to the current ripple voltage.

3. The method according to claim 1, characterized in that The obtaining of the current output comparison result includes: Acquire a preset reference voltage and a current detected output voltage corresponding to the control object; A difference between the preset reference voltage and the current detection output voltage is obtained and used as the current output comparison result.

4. The method according to claim 3, characterized in that: The step of sequentially subjecting the current output comparison result and the current comparison result of the current control output voltage to amplitude limiting and pulse frequency modulation and inputting the result to a control object connected to the LLC output ripple voltage detection control circuit comprises: Obtaining a current comparison result between the current output comparison result and the current control output voltage; The current comparison result is subjected to voltage limiting processing by a voltage limiting circuit to obtain a current voltage limiting result; The current voltage limiting result is subjected to pulse frequency modulation processing by a pulse frequency modulation circuit to obtain a current regulated output voltage, and the current regulated output voltage is input to the control object.

5. An LLC output ripple voltage detection control circuit, characterized in that: It includes a filtering circuit, a subtraction circuit, a repetitive controller and a PID controller, wherein the input end of the filtering circuit is connected to the output end of the LLC circuit, the output end of the filtering circuit is connected to the second input end of the subtraction circuit, the output end of the LLC circuit is also connected to the first input end of the subtraction circuit, and the output end of the subtraction circuit is connected to the PID controller through the repetitive controller; The filter circuit is used to obtain the current input voltage of the LLC circuit, and obtain the current filter circuit output voltage corresponding to the current input voltage; The subtraction circuit is used to compare the current input voltage with the current filtered output voltage to obtain a current ripple voltage; The repetitive controller is used to control the current ripple voltage to obtain a current controlled output voltage; The PID controller is used to obtain a current output comparison result, and subject the current output comparison result and the current comparison result of the current control output voltage to limiting and pulse frequency modulation in sequence and input them into a control object connected to the LLC output ripple voltage detection control circuit.

6. The LLC output ripple voltage detection control circuit according to claim 5, characterized in that: The filtering circuit includes a first resistor, a second resistor, a third resistor, a first capacitor and a second capacitor; the first end of the first resistor is connected to the output end of the LLC circuit; the first end of the first capacitor is connected to the second end of the first resistor, and the second end of the first capacitor is grounded; the first end of the second resistor is connected to the second end of the first resistor; the first end of the second capacitor is connected to the second end of the second resistor, and the second end of the second capacitor is grounded; the first end of the third resistor is connected to the second end of the second resistor, and the second end of the third resistor is connected to the subtraction circuit.

7. The LLC output ripple voltage detection control circuit according to claim 6, characterized in that: The subtraction circuit includes a comparator, a fourth resistor, a fifth resistor, a third capacitor and a fourth capacitor; the negative input terminal of the comparator is connected to the second end of the third resistor and is also connected to the first end of the fourth resistor; the second end of the fourth resistor is connected to the output terminal of the comparator; the first end of the third capacitor is connected to the negative input terminal of the comparator, and the second end of the third capacitor is connected to the output terminal of the comparator; the first end of the fifth resistor is grounded, and the second end of the fifth resistor is connected to the positive input terminal of the comparator; the fourth capacitor is connected in parallel with the fifth resistor.

8. The LLC output ripple voltage detection control circuit according to claim 6, characterized in that: The controlling and processing the current ripple voltage to obtain the current controlled output voltage includes: An input ripple signal corresponding to the current ripple voltage is received and control processing is performed based on a repetitive control model in the repetitive controller to obtain the current controlled output voltage corresponding to the current ripple voltage.

9. The LLC output ripple voltage detection control circuit according to claim 6, characterized in that: The obtaining of the current output comparison result includes: Acquiring a preset reference voltage and a current detected output voltage corresponding to the control object; A difference between the preset reference voltage and the current detection output voltage is obtained and used as the current output comparison result.

10. The LLC output ripple voltage detection control circuit according to claim 9, characterized in that: The step of sequentially subjecting the current output comparison result and the current comparison result of the current control output voltage to amplitude limiting and pulse frequency modulation and inputting the result to a control object connected to the LLC output ripple voltage detection control circuit comprises: Obtaining a current comparison result between the current output comparison result and the current control output voltage; The current comparison result is subjected to voltage limiting processing by a voltage limiting circuit to obtain a current voltage limiting result; The current voltage limiting result is subjected to pulse frequency modulation processing by a pulse frequency modulation circuit to obtain a current regulated output voltage, and the current regulated output voltage is input to the control object.

Images