A control method, apparatus and controller for an LLC converter

Abstract

A control method, apparatus, and controller for an LLC converter are disclosed. When the output voltage of the LLC converter is less than a set lower threshold or greater than a set upper threshold, the controller can calculate a comparison voltage based on the output current or the slope of the output voltage at the LLC converter's output terminal. Since the output voltage has a certain delay, the controller can select the voltage with the smaller value between the output voltage and the comparison voltage at the same moment to adjust the output voltage. The controller calculates the transmission frequency based on the adjusted voltage, enabling rapid adjustment of the output voltage at the LLC converter's output terminal to maintain a stable output voltage.

Description

Technical Field

[0001] This invention relates to the field of circuit control technology, and in particular to a control method, apparatus and controller for an LLC converter. Background Technology

[0002] A resonant inductor (L), resonant capacitor (C) converter is a power converter that transforms direct current (DC) into alternating current (AC) or vice versa, providing power to loads with varying voltages. If a load is added to the output of an LLC converter, its output voltage decreases. Conversely, if the load is reduced, its output voltage increases. Therefore, the output voltage of an LLC converter varies with the load, affecting its stability and limiting its application scenarios. Summary of the Invention

[0003] To address the aforementioned problems, embodiments of this application provide a control method, apparatus, and controller for an LLC converter. When the load at the output terminal of the LLC converter increases or decreases, the output voltage of the LLC converter will increase or decrease. Since the output voltage has a certain delay, the controller calculates a comparison voltage using the transformation slope of the output current or output voltage. The controller can select the voltage with the smaller value between the output voltage and the comparison voltage at the same moment to adjust the output voltage. Based on the adjusted voltage, the controller calculates the transmission frequency, enabling rapid adjustment of the output voltage at the LLC converter's output terminal, keeping the output voltage stable.

[0004] Therefore, the following technical solutions are adopted in the embodiments of this application:

[0005] In a first aspect, this application provides a control method for an LLC converter, the method being executed by a controller, comprising: receiving the output voltage of the output terminal of the LLC converter; determining a comparison voltage when the output voltage is less than a lower voltage threshold or greater than an upper voltage threshold, the comparison voltage being determined based on the output current of the output terminal of the LLC converter or the transformation slope of the output voltage; determining a fitting voltage based on the output voltage and the comparison voltage, the fitting voltage being the voltage that conforms to a set rule between the output voltage and the comparison voltage at the same time; and determining the frequency of an output pulse signal based on the fitting voltage.

[0006] In this embodiment, increasing or decreasing the load at the output of the LLC converter will cause the output voltage of the LLC converter to increase or decrease. When the output voltage of the LLC converter is less than a set lower threshold or greater than a set upper threshold, the controller can calculate a comparison voltage based on the output current or the slope of the output voltage at the LLC converter's output. Since the output voltage has a certain delay, the controller can select the voltage with the smaller value between the output voltage and the comparison voltage at the same time to adjust the output voltage. The controller calculates the transmission frequency based on the adjusted voltage, which can quickly adjust the output voltage at the LLC converter's output to keep the output voltage stable.

[0007] In one embodiment, prior to determining the comparison voltage, the method further includes receiving the output current at the output terminal of the LLC converter.

[0008] In this implementation, the controller samples the current from the LLC converter in real time faster than it samples the voltage. The sampled voltage and current received by the controller at the same moment are actually the output current and output voltage of the LLC converter at different times. The controller can use the output current to calculate a comparison voltage and adjust the sampled voltage to reduce the sampling voltage delay.

[0009] In one embodiment, determining the comparison voltage specifically includes: comparing the output current with a stored current-voltage correspondence table to determine the comparison voltage corresponding to the output current, wherein the current-voltage correspondence table is a pre-set mapping table of different currents corresponding to different voltages.

[0010] In one embodiment, before determining the comparison voltage, the method further includes: when the output voltage is less than the lower voltage threshold or greater than the upper voltage threshold, determining the transformation slope of the output voltage based on the output voltage.

[0011] In this embodiment, the transformation slope of the output voltage calculated by the controller can generally predict the trend of output voltage change. The controller can calculate the comparison voltage based on the transformation slope of the sampled voltage. The controller adjusts the output voltage by receiving the output voltage and the comparison voltage at the same time, thereby reducing the delay of the sampling voltage.

[0012] In one embodiment, determining the comparison voltage specifically includes: comparing the transformation slope of the output voltage with a slope-voltage correspondence table stored therein to determine the comparison voltage corresponding to the transformation slope of the output voltage, wherein the slope-voltage correspondence table is a pre-set mapping relationship table of different voltages corresponding to different transformation slopes of different output voltages.

[0013] In one embodiment, determining the fitted voltage specifically includes: selecting the voltage with the smaller voltage value among the output voltage and the comparison voltage at the same time as the fitted voltage.

[0014] In one embodiment, the output voltage is greater than the upper voltage threshold, and determining the frequency of the output pulse signal based on the fitted voltage specifically includes: increasing the frequency of the output pulse signal when the fitted voltage is the comparison voltage.

[0015] In this embodiment, after a load is applied to the output of the LLC converter for a period of time, the output voltage received by the controller is greater than the comparison voltage. The voltage input to the frequency generator by the controller is the comparison voltage, and the output frequency of the frequency generator increases. At this time, the controller delays and stops sending PWM signals to the gates of each MOS transistor of the LLC converter, thereby increasing the output voltage at the output of the LLC converter.

[0016] In one embodiment, the output voltage is less than the lower limit voltage threshold, and determining the frequency of the output pulse signal based on the fitted voltage specifically includes: when the fitted voltage is the comparison voltage, reducing the frequency of the output pulse signal.

[0017] In one embodiment, at the start of load reduction at the output of the LLC converter, due to a time delay in the controller acquiring the output voltage, the output voltage received by the controller is larger than the comparison voltage. The controller inputs the comparison voltage to the frequency generator, reducing the output frequency of the frequency generator. At this time, the controller sends PWM signals to the gates of each MOS transistor of the LLC converter in advance, thereby reducing the output voltage at the output of the LLC converter.

[0018] Secondly, this application provides a controller, comprising: a preprocessing unit, configured to receive the output voltage of an LLC converter output terminal and determine whether the output voltage is less than a lower voltage threshold or greater than an upper voltage threshold; and when the output voltage is less than the lower voltage threshold or greater than the upper voltage threshold, to send the output voltage to a dynamic control unit and a loop control unit; the dynamic control unit, configured to determine a comparison voltage and send the comparison voltage to a frequency modulation control unit, the comparison voltage being determined based on the output current of the LLC converter output terminal or the transformation slope of the output voltage; the loop control unit, configured to send the output voltage to the frequency modulation control unit; the frequency modulation control unit, configured to determine a fitting voltage based on the output voltage and the comparison voltage, the fitting voltage being the voltage that conforms to a set rule between the output voltage and the comparison voltage at the same time; and to determine the frequency of an output pulse signal based on the fitting voltage.

[0019] In one embodiment, the dynamic control unit is further configured to receive the output current at the output terminal of the LLC converter.

[0020] In one embodiment, the dynamic control unit is specifically used to compare the output current with its own stored current-voltage correspondence table to determine the comparison voltage corresponding to the output current. The current-voltage correspondence table is a pre-set mapping relationship table of different currents corresponding to different voltages.

[0021] In one embodiment, the dynamic control unit is further configured to determine the transformation slope of the output voltage based on the output voltage.

[0022] In one embodiment, the dynamic control unit is specifically used to compare the transformation slope of the output voltage with its own stored slope-voltage correspondence table to determine the comparison voltage corresponding to the transformation slope of the output voltage. The slope-voltage correspondence table is a pre-set mapping relationship table of different voltages corresponding to different transformation slopes of different output voltages.

[0023] In one embodiment, the frequency modulation control unit is specifically used to select the voltage with the smaller voltage value among the output voltage and the comparison voltage at the same time as the fitting voltage.

[0024] In one embodiment, when the output voltage is greater than the upper voltage threshold, the frequency modulation control unit is specifically used to increase the frequency of the output pulse signal when the fitted voltage is the comparison voltage.

[0025] In one embodiment, when the output voltage is less than the lower limit voltage threshold, the frequency modulation control unit is specifically used to reduce the frequency of the output pulse signal when the fitted voltage is the comparison voltage.

[0026] Thirdly, this application provides a control device for an LLC converter, characterized in that the control device performs the various possible implementations of the first aspect.

[0027] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the various possible implementations of the first aspect.

[0028] Fifthly, this application provides a computer program product, characterized in that the computer program product stores instructions that, when executed by a computer, cause the computer to implement the various possible embodiments of the first aspect. Attached Figure Description

[0029] The accompanying drawings used in the description of the embodiments or prior art are briefly introduced below.

[0030] Figure 1 This is a circuit topology diagram of an LLC converter in the prior art;

[0031] Figure 2 This is a control circuit topology diagram of an LLC converter in the prior art;

[0032] Figure 3 This is a control circuit topology diagram of an LLC converter provided in the embodiments of this application;

[0033] Figure 4 This is a schematic diagram of the control circuit of an LLC converter provided in an embodiment of this application;

[0034] Figure 5 This is a flowchart illustrating a control method for an LLC converter provided in an embodiment of this application.

[0035] Figure 6 This is an experimental data graph showing the relationships between various data points in a simulation experiment provided in this application embodiment;

[0036] Figure 7 This is a schematic diagram of the architecture of a control device for an LLC converter provided in an embodiment of this application. Detailed Implementation

[0037] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0038] In this article, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The symbol " / " in this article indicates that the related objects are in an "or" relationship; for example, A / B means A or B.

[0039] The terms "first" and "second," etc., used in the specification and claims herein are used to distinguish different objects, not to describe a specific order of objects. For example, "first response message" and "second response message," etc., are used to distinguish different response messages, not to describe a specific order of response messages.

[0040] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0041] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0042] A spectrum emission mask (SEM) is used to measure spurious energy in the spectral range of 2.5MHz to 12.75MHz off-carrier center frequency. The SEM is an "in-band indicator," providing a "spectral template." When measuring in-band spectral leakage of a transmitter, the SEM can be used to identify points that do not exceed the template limits. The SEM reflects the points exceeding the limits within a small measurement bandwidth in adjacent frequency bands, representing the energy value of glitches in the transmit power in the frequency domain.

[0043] When wireless communication equipment is operating, the built-in LLC converter generates voltage fluctuations as the load of the wireless communication equipment changes. The high-frequency components in the dynamic waveform of the LLC converter are modulated onto the power amplifier output and transmitted with the radio frequency signal. The SEM (Search Engine Optimization) specification requires that, within a certain bandwidth of the main signal, the high-frequency glitches on the system's radio frequency output power module meet certain requirements. In time-division duplex (TDD) systems, the impact of LLC converter dynamics on SEM is even more pronounced.

[0044] Figure 1 This is a circuit topology diagram of an LLC converter in the prior art. (Example:) Figure 1 As shown, the LLC converter 100 includes an input terminal, a first switching circuit S1, a second switching circuit S2, a resonant circuit, a transformer, a first diode D3, a second diode D4, and an output terminal. The input terminal of the LLC converter 100 receives a DC voltage V. IN Then, the DC voltage V can be... IN It is converted into DC voltage V0 at a set voltage, so as to provide electrical energy to loads with different voltages.

[0045] The first switching circuit S1 and the second switching circuit S2 are connected in series, and the branches containing the first switching circuit S1 and the second switching circuit S2 are coupled at both ends of the input terminal. The switching circuit includes a metal-oxide-semiconductor field-effect transistor (MOSFET), a diode, and a capacitor. The MOSFET, diode, and capacitor are connected in parallel. MOSFETs Q1 and Q2 constitute the inverter section of the switching network. Diode D1 is the body diode of MOSFET Q1, and diode D2 is the body diode of MOSFET Q2. Diodes D1 and D2 allow the LLC converter 100 to operate with freewheeling during the dead time. Capacitor C1 is the parasitic capacitance of MOSFET Q1, and capacitor C2 is the parasitic capacitance of MOSFET Q2. The DC current V input to the input terminal... IN After being alternately driven by the first switching circuit S1 and the second switching circuit S2, the current is inverted into alternating current. At this time, the voltage waveform of the alternating current is a square wave.

[0046] The resonant circuit includes resonant inductors Lr and Lm, and resonant capacitor Cr. The resonant inductors Lr and Cr are connected in series. One end of the branch containing Lr and Cr is coupled to one port of the primary winding of the transformer, and the other end is coupled to the node between the first switching circuit S1 and the second switching circuit S2. The resonant inductor Lm is connected in parallel with the primary winding of the transformer, coupled to both ports of the primary winding. The resonant circuit can resonate the AC voltage waveform from a square wave to an approximately sinusoidal waveform.

[0047] The transformer has two resonant frequencies. When the resonant inductance Lr and resonant capacitance Cr in the resonant circuit participate in resonance, the transformer's resonant frequency fr is:

[0048]

[0049] When the resonant inductance Lr, resonant inductance Lm, and resonant capacitance Cr in the resonant circuit participate in resonance, the resonant frequency fm of the transformer is:

[0050]

[0051] The secondary winding of the transformer includes a first port, a second port, and a third port. The first and third ports are located on opposite sides of the secondary winding, and the second port is located between the first and third ports. The first port of the secondary winding is connected in series with diode D3, and the third port is connected in series with diode D4. Diodes D3 and D4 are connected in reverse series. One end of the output terminal is coupled to the node between diodes D3 and D4, and the other end is coupled to the second port of the secondary winding. The electrical connection between the first and third ports of the secondary winding and the diodes rectifies the alternating current (AC) output from the transformer, converting it into direct current (DC). The DC voltage output is related to the number of turns in the coil between the first and second ports of the secondary winding. The more turns in the coil between the first and second ports of the secondary winding, the higher the DC voltage output.

[0052] In the existing LLC converter 100, when the input DC voltage is fixed, the output DC voltage is also fixed. To broaden the application scenarios of the LLC converter 100 and enable it to provide power to loads with different rated voltages, a controller is added. The controller controls the LLC converter 100, allowing it to output DC voltages at different voltages.

[0053] Figure 2 This is a control circuit topology diagram of an LLC converter in the prior art. (Example:) Figure 2 As shown, the control circuit 200 of the LLC converter includes an LLC converter 210, a voltage sampling circuit 220, and a proportional-integral (PI) controller 230. The LLC converter 210 can be as follows: Figure 1 The LLC converter 100 is shown. The input terminal of the voltage sampling circuit 220 is coupled to the output terminal of the LLC converter 210, and the output terminal of the voltage sampling circuit 220 is coupled to the PI controller 230. The voltage sampling circuit 220 samples the voltage at the output terminal of the LLC converter 210 and inputs the sampled voltage value to the PI controller 230. The output terminal of the PI controller 230 is electrically connected to the gate of the MOS transistor in the first switching circuit S1 and the gate of the MOS transistor in the second switching circuit S2 in the LLC converter 210, respectively. After receiving the sampled voltage, the PI controller 230 controls whether to send a pulse width modulation (PWM) signal to the gate of each MOS transistor and the duration of the PWM signal transmission.

[0054] When a load is added to the output of LLC converter 210, the output voltage of LLC converter 210 will suddenly decrease. At this time, the sampled voltage at the output of LLC converter 210 suddenly decreases, and PI controller 230 delays sending a PWM signal to LLC converter 210, or delays stopping sending a PWM signal to LLC converter 210. During the delay, LLC converter 210 charges the resonant capacitor Cr through the magnetizing current, causing the voltage at the output of LLC converter 210 to quickly increase to a stable value. The delay time is related to the load current and the transformer magnetizing inductance.

[0055] When the load decreases at the output of LLC converter 210, the output voltage of LLC converter 210 will suddenly increase. At this time, the sampled voltage at the output of LLC converter 210 suddenly increases, and PI controller 230 either sends a PWM signal to LLC converter 210 earlier or stops sending a PWM signal to LLC converter 210 earlier. During this earlier time, the resonant capacitor Cr is not sufficiently charged, causing the output voltage of LLC converter 210 to quickly drop to a stable value. The earlier time is related to the load current and the resonant period.

[0056] In the existing control circuit 200 of the LLC converter, when the output voltage of the LLC converter 210 suddenly decreases or increases, the PI controller 230 can increase or decrease the output voltage of the LLC converter 210 to avoid excessive voltage fluctuations. However, the existing PI controller 230 has a certain lag in regulating the output voltage of the LLC converter 210; it only increases or decreases the output voltage of the LLC converter 210 after the output voltage has increased or decreased to a certain value. Therefore, the existing PI controller 230 has limited ability to regulate the output voltage of the LLC converter 210.

[0057] Furthermore, in existing LLC converters, the control circuit 200 uses a traditional PI value for adjustment to accelerate loop response and reduce output voltage overshoot under dynamic loads, thereby minimizing the impact on SEM indicators. However, the control circuit 200's use of sampled output voltage for traditional PI control and parallel output capacitors to reduce output voltage overshoot under dynamic loads has several drawbacks. For example, parallel connection of multiple output capacitors increases layout area and costs; traditional PI control has limited ability to regulate dynamic overshoot.

[0058] Figure 3This is a control circuit topology diagram of an LLC converter provided in an embodiment of this application. Figure 3 As shown, the control circuit 300 of the LLC converter includes an LLC converter 310, a voltage sampling circuit 320, a current sampling circuit 330, and a controller 340. In this application, the LLC converter 310 can be as follows: Figure 1 The LLC converter 100 shown can also be other types of LLC converters, which are not limited here.

[0059] The input terminal of the voltage sampling circuit 320 is coupled to the output terminal of the LLC converter 310, and the output terminal of the voltage sampling circuit 320 is coupled to the controller 330. The voltage sampling circuit 320 obtains a sampled voltage by sampling the voltage at the output terminal of the LLC converter 310. The voltage sampling circuit 320 inputs the sampled voltage value to the controller 330. Optionally, the voltage sampling circuit 320 can be a voltage divider resistor. The voltage divider resistor is coupled between the output terminal of the LLC converter 310 and the controller 340. After the output voltage at the output terminal of the LLC converter 310 passes through the voltage divider resistor, the output voltage value is reduced. After the voltage divider resistor reduces the output voltage to a set threshold, it is input to the controller 330.

[0060] In this application, if the LLC converter 310 is used in the power supply system of a communication device, the voltage at the output terminal of the LLC converter 310 is typically between 0 and 12V. The sampling voltage input to the controller 340 by the voltage sampling circuit 320 is typically between 0 and 3V. Therefore, a differential circuit can be connected in parallel at the output terminal of the LLC converter 310, and the input terminal of the voltage sampling circuit 320 is coupled to the differential circuit, enabling the voltage sampling circuit 320 to output a voltage with a set voltage threshold to the controller 340. In one embodiment, such as Figure 3 As shown, the differential circuit includes resistors R2 and R3. Resistors R2 and R3 are connected in series and in parallel at the output of LLC converter 310. The input of voltage sampling circuit 320 is coupled to the node between resistors R2 and R3.

[0061] The input terminal of the current sampling circuit 330 is coupled to the output terminal of the LLC converter 310, and the output terminal of the current sampling circuit 330 is coupled to the controller 330. The current sampling circuit 330 samples the current at the output terminal of the LLC converter 310 and inputs the sampled current value to the controller 330. Optionally, the current sampling circuit 330 can be a differential amplifier. One input terminal of the differential amplifier is coupled to the output terminal of the LLC converter 310, the other input terminal of the differential amplifier is electrically connected to the output terminal, and the output terminal of the differential amplifier is coupled to the controller 340. The differential amplifier acquires the current output from the output terminal of the LLC converter 310 and samples and holds the input current. The differential amplifier inputs the sampled current to the controller 340.

[0062] Controller 330 refers to a device with processing capabilities, such as a microcontroller unit (MCU), system-on-a-chip (SoC), or other controller. The input terminals of controller 330 are coupled to voltage sampling circuit 320 and current sampling circuit 330, respectively. The output terminals of controller 330 are coupled to the gates of the MOS transistors in the first switching circuit S1 and the second switching circuit S2, respectively. In this application, when the output terminal of LLC converter 310 is subjected to a load increase or decrease, controller 330 receives the voltage and current values ​​at the output terminal of LLC converter 310 and controls whether to send PWM signals to the gates of each MOS transistor, as well as the timing of sending the PWM signals, to quickly adjust the voltage at the output terminal of LLC converter 310 and improve the stability of LLC converter 310.

[0063] In the embodiments of this application, such as Figure 4 As shown, the controller 330 can be divided into a preprocessing unit 341, a dynamic control unit 342, a loop control unit 343, and a frequency modulation control unit 344 according to the functions it performs.

[0064] In one embodiment, the preprocessing unit 341 receives the sampled voltage from the voltage sampling circuit 320 and determines the relationship between the sampled voltage and a voltage threshold. The voltage threshold refers to the maximum allowable fluctuation range of the sampled voltage, including an upper voltage threshold and a lower voltage threshold. When the load is increased at the output of the LLC converter 310, the sampled voltage of the voltage sampling circuit 320 decreases, typically falling below the lower voltage threshold. When the load is decreased at the output of the LLC converter 310, the sampled voltage of the voltage sampling circuit 320 increases, typically exceeding the upper voltage threshold.

[0065] In one embodiment, when the sampled voltage is between the upper voltage threshold and the lower voltage threshold, the preprocessing unit 341 inputs the sampled voltage to the loop control unit 343.

[0066] In one embodiment, when the sampled voltage is outside the upper voltage threshold and the lower voltage threshold, the preprocessing unit 341 inputs the sampled voltage to the dynamic control unit 342 and the loop control unit 343.

[0067] In one embodiment, after receiving the sampled voltage, the loop control unit 343 regulates and holds the sampled voltage, and inputs the stable sampled voltage to the frequency modulation control unit 344. Optionally, the loop control unit 343 is provided with a voltage loop. When the loop control unit 343 receives the sampled voltage from the preprocessing unit 341, the voltage loop regulates and holds the sampled voltage to keep it stable. The loop control unit 343 then inputs the stable sampled voltage to the frequency modulation control unit 344.

[0068] In one embodiment, after receiving the sampled current from the current sampling circuit 330, the dynamic control unit 342 compares the sampled current with a current-voltage (U / I) correspondence table stored in a database. The current-voltage correspondence table is a pre-defined table stored in memory. It records different voltage values ​​corresponding to different current values. In the table, the current value and voltage value are directly proportional; that is, the larger the current value, the larger the corresponding voltage value. After comparing the sampled current with the current-voltage correspondence table, the dynamic control unit 342 determines the voltage value of the comparison voltage input to the frequency modulation control unit 344 and outputs the comparison voltage to the frequency modulation control unit 344. In other embodiments, the corresponding values ​​between the current and voltage values ​​in the current-voltage correspondence table are not limited and are determined specifically according to the application scenario of the LLC converter control circuit 300.

[0069] In one embodiment, after receiving a sampled voltage, the dynamic control unit 342 calculates the transformation slope of the sampled voltage. The dynamic control unit 342 compares the transformation slope of the sampled voltage with a slope-voltage (k / I) correspondence table stored in a database. This slope-voltage correspondence table is a pre-defined table stored in memory. It records different voltage values ​​corresponding to different transformation slopes of the sampled voltage. In the slope-voltage correspondence table, the transformation slope of the sampled voltage is directly proportional to the voltage value. That is, the larger the transformation slope of the sampled voltage, the larger the corresponding voltage value. After comparing the transformation slope of the sampled voltage with the slope-voltage correspondence table, the dynamic control unit 342 determines the voltage value of the comparison voltage input to the frequency modulation control unit 344. In other embodiments, the numerical values ​​corresponding to the transformation slope of the sampled voltage and the voltage value in the slope-voltage correspondence table are not limited and are determined specifically according to the application scenario of the control circuit 300 of the LLC converter.

[0070] In one embodiment, after calculating the comparison voltage, the dynamic control unit 342 inputs the comparison data to the loop control unit 343. The current sampling circuit 330 collects the sampled current in real time faster than the voltage sampling circuit 320 collects the sampled voltage in real time. The sampled voltage and comparison voltage received by the loop control unit 343 at the same time are actually the output current and output voltage of the LLC converter 310 at different times. After obtaining the comparison voltage, the loop control unit 343 adjusts the sampled voltage to reduce the sampling voltage delay.

[0071] The slope of the sampled voltage transformation calculated by the dynamic control unit 342 can generally predict the trend of the sampled voltage change. The dynamic control unit 342 can calculate the comparison voltage based on the slope of the sampled voltage transformation. The loop control unit 343 receives the sampled voltage and the comparison voltage at the same time and adjusts the sampled voltage to reduce the sampling voltage delay.

[0072] In one embodiment, after receiving the sampled voltage from the loop control unit 343 and the comparison voltage from the dynamic control unit 342, the frequency modulation control unit 344 fits the sampled voltage and the comparison voltage. The frequency modulation control unit 344 selects the voltage with the smaller value from the sampled voltage and the comparison voltage at the same time, following the principle of selecting the smaller value.

[0073] After obtaining the fitted voltage, the frequency modulation control unit 344 determines whether to send a PWM signal to the gate of each MOS transistor based on the voltage value at different times. The timing of sending the PWM signal to the gate of each MOS transistor by the frequency modulation control unit 344 is related to the fitted voltage value. Optionally, the frequency modulation control unit 344 includes a frequency generator. The frequency modulation control unit 344 inputs the fitted voltage value to the frequency generator, and the frequency generator determines the frequency of the waveform emitted by the frequency modulation control unit 344 based on the input voltage value.

[0074] When a load is added to the output of LLC converter 310, the sampling voltage of voltage sampling circuit 320 decreases. The sampling voltage is lower than the lower voltage threshold, and dynamic control unit 342 outputs a comparison voltage. The sampling current of current sampling circuit 330 increases, and the comparison voltage output by dynamic control unit 342 increases. At the initial moment when a load is added to the output of LLC converter 310, due to the time delay between the sampling voltage input from loop control unit 343 and frequency modulation control unit 344, the sampling voltage received by loop control unit 343 is smaller than the comparison voltage. Loop control unit 343 inputs the sampling voltage to the frequency generator, and the output frequency of the frequency generator remains unchanged.

[0075] After a period of time, the load applied to the output of the LLC converter 310 increases, and the sampled voltage received by the loop control unit 343 is greater than the comparison voltage. The voltage input to the frequency generator from the loop control unit 343 is the comparison voltage, causing the frequency generator to output a higher frequency. At this time, the frequency modulation control unit 344 delays and stops sending PWM signals to the gates of each MOS transistor, thereby increasing the output voltage at the output of the LLC converter 310.

[0076] When the load at the output of LLC converter 310 is reduced, the sampling voltage of voltage sampling circuit 320 increases. Since the sampling voltage exceeds the upper voltage threshold, dynamic control unit 342 outputs a comparison voltage. The sampling current of current sampling circuit 330 decreases, and the comparison voltage output by dynamic control unit 342 decreases. At the beginning of the load reduction at the output of LLC converter 310, due to the time delay between the sampling voltage input from loop control unit 343 and frequency modulation control unit 344, the sampling voltage received by loop control unit 343 is larger than the comparison voltage. Loop control unit 343 inputs the comparison voltage to the frequency generator, reducing the output frequency of the frequency generator. At this time, frequency modulation control unit 344 sends PWM signals to the gates of each MOS transistor in advance, thereby reducing the output voltage at the output of LLC converter 310.

[0077] Figure 6 This is a flowchart illustrating a control method for an LLC converter provided in an embodiment of this application. Figure 6As shown, the process by which the controller controls the output voltage at the output terminal of the LLC converter is as follows:

[0078] Step S601: Receive the output voltage at the output terminal of the LLC converter.

[0079] Specifically, a voltage sampling circuit can be coupled between the controller 330 and the output of the LLC converter. The voltage sampling circuit can sample the output of the LLC converter in real time and input the output voltage into the controller.

[0080] Optionally, a current sampling circuit can be coupled between the controller 330 and the output of the LLC converter. The current sampling circuit can sample the output of the LLC converter in real time and input the output current into the controller.

[0081] Step S602: Determine whether the output voltage is less than the lower voltage threshold or greater than the upper voltage threshold. If the output voltage is less than the lower voltage threshold or greater than the upper voltage threshold, proceed to step S603; if the output voltage is neither less than the lower voltage threshold nor greater than the upper voltage threshold, proceed to step S605.

[0082] Specifically, after receiving the output voltage of the LLC converter, the controller 330 preprocesses the output voltage. The controller 330 can preset a normal voltage fluctuation range. The normal voltage range includes a lower voltage threshold and an upper voltage threshold. In one embodiment, if the load at the output of the LLC converter increases, the output voltage will decrease. If the output voltage received by the controller 330 is less than the lower voltage threshold, the controller 330 can determine that the load at the output of the LLC converter has increased. In another embodiment, if the load at the output of the LLC converter decreases, the output voltage will increase. If the output voltage received by the controller 330 is greater than the upper voltage threshold, the controller 330 can determine that the load at the output of the LLC converter has decreased.

[0083] Step S603: Determine the comparison voltage. The comparison voltage is a voltage determined based on the slope of the output current or output voltage at the output terminal of the LLC converter.

[0084] In one embodiment, after receiving the output current, the controller 330 compares the output current with a current-voltage (U / I) correspondence table stored in a database. The current-voltage correspondence table is a pre-defined table stored in memory. It records that different current values ​​correspond to different voltage values. In the current-voltage correspondence table, the current value and the voltage value are directly proportional; that is, the larger the current value, the larger the corresponding voltage value. After comparing the output current with the current-voltage correspondence table, the controller 330 determines the voltage value for comparison. The controller 330 can generate the comparison voltage based on the output voltage. In other embodiments, the corresponding values ​​between the current value and the voltage value in the current-voltage correspondence table are not limited and are determined specifically according to the application scenario of the LLC converter.

[0085] In one embodiment, after receiving the output voltage, the controller 330 compares the output voltage's transformation slope with a slope-voltage (k / I) correspondence table stored in a database. The slope-voltage correspondence table is a pre-defined table stored in memory. It records different voltage values ​​corresponding to different output voltage transformation slopes. In the table, the output voltage transformation slope and voltage value are directly proportional; that is, the larger the output voltage transformation slope, the larger the corresponding voltage value. The controller 330 determines the voltage value of the comparison voltage after comparing the output voltage transformation slope with the slope-voltage correspondence table. In other embodiments, the numerical values ​​corresponding to the output voltage transformation slope and voltage value in the slope-voltage correspondence table are not limited and are determined specifically according to the application scenario of the LLC converter.

[0086] Step S604: Determine the fitted voltage based on the output voltage and the comparison voltage.

[0087] Specifically, after obtaining the output voltage and the comparison voltage, the controller 330 fits the output voltage and the comparison voltage. Following the principle of selecting the smaller value, the controller 330 selects the voltage with the smaller value between the output voltage and the comparison voltage at the same time. After obtaining the fitted voltage, the controller 330 determines whether to send a PWM signal to the gate of each MOS transistor of the LLC converter based on the voltage value at different times. The timing of the controller 330 sending the PWM signal to the gate of each MOS transistor of the LLC converter is related to the fitted voltage value.

[0088] In this application, the current sampling circuit acquires the output current at a faster rate than the voltage sampling circuit acquires the output voltage in real time. Therefore, the output voltage and comparison voltage received by the controller 330 at the same moment are actually the output current and output voltage of the LLC converter at different moments.

[0089] Step S605: Determine the frequency of the output pulse signal.

[0090] Specifically, the controller 330 includes a frequency generator. If the output voltage is not less than a lower voltage threshold and not greater than an upper voltage threshold, the controller 330 inputs the output voltage to the frequency generator, which determines the frequency of the emitted wave based on the output voltage value. If the output voltage is less than the lower voltage threshold or greater than the upper voltage threshold, the controller 330 inputs a fitted voltage value to the frequency generator, which determines the frequency of the emitted wave based on the input voltage value.

[0091] In one embodiment, if the output voltage received by controller 330 is less than the lower voltage threshold, it indicates that an increased load has been added to the output of the LLC converter, causing a decrease in the output voltage of the voltage sampling circuit. At this time, the output current received by controller 330 increases, and the calculated comparison voltage increases. At the initial moment of adding load to the output of the LLC converter, due to the time delay in the controller 330 acquiring the output voltage, the output voltage received by controller 330 is smaller than the comparison voltage. Controller 330 inputs the output voltage to the frequency generator, and the frequency generator outputs a constant waveform frequency.

[0092] After a period of time, the output voltage received by the controller 330 is greater than the comparison voltage. The voltage input to the frequency generator from the controller 330 is the comparison voltage, causing the frequency generator to output a higher frequency. At this point, the controller 330 delays sending PWM signals to the gates of the MOS transistors in the LLC converter, thereby increasing the output voltage at the LLC converter's output terminal.

[0093] In one embodiment, if the output voltage received by controller 330 is greater than the upper voltage threshold, it indicates that the load at the output of the LLC converter has decreased, causing the output voltage of the voltage sampling circuit to rise. At this time, the output current received by controller 330 decreases, and the calculated comparison voltage decreases.

[0094] At the initial moment of load reduction at the output of the LLC converter, due to the time delay in the controller 330 acquiring the output voltage, the output voltage received by the controller 330 is larger than the comparison voltage. The controller 330 inputs the comparison voltage to the frequency generator, reducing the output frequency of the frequency generator. At this time, the controller 330 sends PWM signals to the gates of each MOS transistor of the LLC converter in advance, thereby reducing the output voltage at the output of the LLC converter.

[0095] In this embodiment, increasing or decreasing the load at the output terminal of the LLC converter will cause the output voltage of the LLC converter to increase or decrease. When the output voltage of the LLC converter is less than a set lower threshold or greater than a set upper threshold, the controller can calculate a comparison voltage based on the output current or the slope of the output voltage at the output terminal of the LLC converter. Since the output voltage has a certain delay, the controller can select the voltage with the smaller value between the output voltage and the comparison voltage at the same time to adjust the output voltage. The controller calculates the transmission frequency based on the adjusted voltage, which can quickly adjust the output voltage at the output terminal of the LLC converter to keep the output voltage stable.

[0096] Figure 7 This is a graph showing the experimental data between various data points in a simulation experiment provided in this application embodiment. For example... Figure 7 As shown, when the load at the output of the LLC converter increases, the output current increases, and the output voltage continuously decreases. In the initial stage of the output voltage decrease, the controller keeps the frequency of the PWM signal transmission constant. When the output voltage drops below the lower voltage threshold, the controller increases the frequency of the PWM signal transmission, delaying the transmission of PWM signals to the gates of the various MOS transistors in the LLC converter, thereby increasing the output voltage at the LLC converter's output. The output voltage then rebounds from its low point, continuously increasing until it returns to its original value.

[0097] When the load at the output of the LLC converter decreases, the output current decreases, and the output voltage continuously increases. At the beginning of this voltage decrease, the controller maintains a decreasing frequency of PWM signals, sending PWM signals to the gates of the MOS transistors in the LLC converter in advance to reduce the output voltage at the output of the LLC converter. The output voltage continues to decrease until it returns to its original value.

[0098] Compared Figure 2 Compared with the prior art solutions shown, the control method protected in this application embodiment can adjust the output voltage of the LLC converter faster and make the output voltage more stable.

[0099] Figure 7 This is a schematic diagram of the architecture of a control device for an LLC converter provided in an embodiment of this application. Figure 7 The control device 700 shown includes a preprocessing unit 341, a dynamic control unit 342, a loop control unit 343, and a frequency modulation control unit 344. The specific execution processes of each unit are as follows:

[0100] In one embodiment, the preprocessing unit 341 is used to receive the output voltage of the LLC converter's output terminal and determine whether the output voltage is less than a lower voltage threshold or greater than an upper voltage threshold; and when the output voltage is less than the lower voltage threshold or greater than the upper voltage threshold, it sends the output voltage to the dynamic control unit 342 and the loop control unit 343; the dynamic control unit 342 is used to determine a comparison voltage and send the comparison voltage to the frequency modulation control unit 344, the comparison voltage being determined based on the transformation slope of the output current or output voltage of the LLC converter's output terminal; the loop control unit 343 is used to send the output voltage to the frequency modulation control unit 344; the frequency modulation control unit 344 is used to determine a fitting voltage based on the output voltage and the comparison voltage, the fitting voltage being the voltage that conforms to a set rule between the output voltage and the comparison voltage at the same time; and to determine the frequency of the output pulse signal based on the fitting voltage.

[0101] In one embodiment, the dynamic control unit 342 is also used to receive the output current at the output terminal of the LLC converter.

[0102] In one embodiment, the dynamic control unit 342 is specifically used to compare the output current with its own stored current-voltage correspondence table to determine the comparison voltage corresponding to the output current. The current-voltage correspondence table is a pre-set mapping relationship table of different currents corresponding to different voltages.

[0103] In one embodiment, the dynamic control unit 342 is further configured to determine the transformation slope of the output voltage based on the output voltage.

[0104] In one embodiment, the dynamic control unit 342 is specifically used to compare the transformation slope of the output voltage with its own stored slope-voltage correspondence table to determine the comparison voltage corresponding to the transformation slope of the output voltage. The slope-voltage correspondence table is a pre-set mapping relationship table of different voltages corresponding to different transformation slopes of different output voltages.

[0105] In one embodiment, the frequency modulation control unit 344 is specifically used to select the output voltage at the same time and the voltage with the smaller voltage value among the comparison voltages as the fitting voltage.

[0106] In one embodiment, when the output voltage is greater than the upper voltage threshold, the frequency modulation control unit 344 is specifically used to increase the frequency of the output pulse signal when the fitted voltage is the comparison voltage.

[0107] In one embodiment, when the output voltage is less than the lower limit voltage threshold, the frequency modulation control unit 344 is specifically used to reduce the frequency of the output pulse signal when the fitted voltage is the comparison voltage.

[0108] This application embodiment also provides a computer-readable storage medium storing a computer program thereon, which, when executed in a computer, causes the computer to perform the above-described actions. Figure 5 And any of the methods described in the corresponding description.

[0109] This application also provides a computer program product, which stores instructions that, when executed by a computer, cause the computer to perform the above-described actions. Figure 5 And any of the methods described in the corresponding description.

[0110] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the embodiments of this application.

[0111] Furthermore, various aspects or features of the embodiments of this application can be implemented as methods, apparatus, or articles of manufacture using standard programming and / or engineering techniques. The term "article of manufacture" as used in this application encompasses a computer program accessible from any computer-readable device, carrier, or medium. For example, computer-readable media may include, but are not limited to: magnetic storage devices (e.g., hard disks, floppy disks, or magnetic tapes), optical discs (e.g., compact discs (CDs), digital versatile discs (DVDs), etc.), smart cards, and flash memory devices (e.g., erasable programmable read-only memory (EPROMs), cards, sticks, or key drives, etc.). Additionally, the various storage media described herein may represent one or more devices and / or other machine-readable media for storing information. The term "machine-readable medium" may include, but is not limited to, wireless channels and various other media capable of storing, containing, and / or carrying instructions and / or data.

[0112] In the above embodiments, Figure 7The control device 700 can be implemented wholly or partially through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented wholly or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs (DVDs)), or semiconductor media (e.g., solid-state disks (SSDs)).

[0113] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of this application.

[0114] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0115] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0116] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0117] If the aforementioned function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application embodiment, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a server, or an access network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0118] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application.

Claims

1. A control method for an LLC converter, characterized in that, The method is executed by the controller and includes: Receive the output voltage from the output terminal of the LLC converter; When the output voltage is less than the lower voltage threshold or greater than the upper voltage threshold, a comparison voltage is determined. The comparison voltage is obtained by comparing the output current of the LLC converter with its stored current-voltage correspondence table, or by comparing the transformation slope of the output voltage of the LLC converter with its stored slope-voltage correspondence table. Based on the output voltage and the comparison voltage, a fitting voltage is determined, wherein the fitting voltage is the voltage that conforms to a set rule between the output voltage and the comparison voltage at the same time. The frequency of the output pulse signal is determined based on the fitted voltage.

2. The method according to claim 1, characterized in that, Before determining the comparison voltage, the method further includes: Receive the output current from the output terminal of the LLC converter.

3. The method according to claim 2, characterized in that, The determination of the comparison voltage specifically includes: The output current is compared with the current-voltage correspondence table stored in the system to determine the corresponding voltage. The current-voltage correspondence table is a pre-set mapping table of different voltages corresponding to different currents.

4. The method according to claim 1, characterized in that, Before determining the comparison voltage, the method further includes: When the output voltage is less than the lower voltage threshold or greater than the upper voltage threshold, the transformation slope of the output voltage is determined based on the output voltage.

5. The method according to claim 4, characterized in that, The determination of the comparison voltage specifically includes: The slope of the output voltage transformation is compared with the slope-voltage correspondence table stored in the system to determine the comparison voltage corresponding to the slope of the output voltage transformation. The slope-voltage correspondence table is a pre-set mapping table of different voltages corresponding to different output voltage transformation slopes.

6. The method according to any one of claims 1-5, characterized in that, The determination of the fitted voltage specifically includes: The voltage with the smaller value among the output voltage and the comparison voltage at the same time is selected as the fitting voltage.

7. The method according to claim 6, characterized in that, The output voltage is greater than the upper voltage threshold. Determining the frequency of the output pulse signal based on the fitted voltage specifically includes: When the fitted voltage is the same as the comparison voltage, the frequency of the output pulse signal is increased.

8. The method according to claim 6, characterized in that, The output voltage is less than the lower voltage threshold. Determining the frequency of the output pulse signal based on the fitted voltage specifically includes: When the fitted voltage is the comparison voltage, the frequency of the output pulse signal is reduced.

9. A controller, characterized in that, include: The preprocessing unit is used to receive the output voltage at the output terminal of the LLC converter and determine whether the output voltage is less than the lower voltage threshold or greater than the upper voltage threshold. And when the output voltage is less than the lower voltage threshold or greater than the upper voltage threshold, the output voltage is sent to the dynamic control unit and the loop control unit; The dynamic control unit is used to determine the comparison voltage and send the comparison voltage to the frequency modulation control unit. The comparison voltage is obtained by comparing the output current of the LLC converter with its own stored current-voltage correspondence table, or by comparing the transformation slope of the output voltage of the LLC converter with its own stored slope-voltage correspondence table. The loop control unit is used to send the output voltage to the frequency modulation control unit; The frequency modulation control unit is configured to determine a fitting voltage based on the output voltage and the comparison voltage, wherein the fitting voltage is the voltage that conforms to a set rule between the output voltage and the comparison voltage at the same time; and to determine the frequency of the output pulse signal based on the fitting voltage.

10. The controller according to claim 9, characterized in that, The dynamic control unit is also used to receive the output current at the output terminal of the LLC converter.

11. The controller according to claim 10, characterized in that, The dynamic control unit is specifically used to compare the output current with its own stored current-voltage correspondence table to determine the comparison voltage corresponding to the output current. The current-voltage correspondence table is a pre-set mapping relationship table of different currents corresponding to different voltages.

12. The controller according to claim 9, characterized in that, The dynamic control unit is also configured to determine the transformation slope of the output voltage based on the output voltage.

13. The controller according to claim 12, characterized in that, The dynamic control unit is specifically used to compare the transformation slope of the output voltage with its own stored slope-voltage correspondence table to determine the comparison voltage corresponding to the transformation slope of the output voltage. The slope-voltage correspondence table is a pre-set mapping relationship table of different voltages corresponding to different transformation slopes of different output voltages.

14. The controller according to any one of claims 9-13, characterized in that, The frequency modulation control unit is specifically used to select the voltage with the smaller voltage value among the output voltage and the comparison voltage at the same time as the fitting voltage.

15. The controller according to claim 14, characterized in that, The output voltage is greater than the upper voltage threshold. The frequency modulation control unit is specifically used to increase the frequency of the output pulse signal when the fitted voltage is the comparison voltage.

16. The controller according to claim 14, characterized in that, The output voltage is less than the lower voltage threshold. The frequency modulation control unit is specifically used to reduce the frequency of the output pulse signal when the fitted voltage is the comparison voltage.

17. A control device for an LLC converter, characterized in that, The control device performs the method as described in any one of claims 1-8.

18. A computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the method of any one of claims 1-8.

19. A computer program product, characterized in that, The computer program product stores instructions that, when executed by a computer, cause the computer to perform the method described in any one of claims 1-8.

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