Control Method and Device of Converter, Readable Storage Medium

Abstract

An embodiment of the present application provides a control method and device for a converter, and a readable storage medium. The control method includes: obtaining the real-time input voltage and real-time output voltage of the converter; determining the real-time closed-loop control output value corresponding to the converter according to the real-time input voltage, the real-time output voltage, and a preset closed-loop control algorithm; determining the real-time control strategy of the switching tube of the converter from at least three preset control strategies according to the real-time closed-loop control output value; and controlling the switching tube according to the real-time control strategy. This control method is used to achieve efficient and high-precision voltage regulation control.

Description

Technical Field

[0001] This application relates to the technical field of circuit control, and particularly to a control method and device for a converter, and a readable storage medium. Background Art

[0002] A converter includes multiple switching tubes. By controlling the conduction or cutoff of the switching tubes, the converter can convert the voltage. To achieve the voltage stabilization control of the converter, the converter is usually provided with a voltage stabilization control unit for realizing the stable output of the voltage.

[0003] In the prior art, the voltage stabilization control is realized by intermittently controlling the conduction and cutoff of the switching tubes. However, the control accuracy of this control method is poor, and the efficiency of the voltage stabilization control is not ideal. Summary of the Invention

[0004] The purpose of this application is to provide a control method and device for a converter, and a readable storage medium, so as to achieve high-efficiency and high-precision voltage stabilization control.

[0005] In a first aspect, this application provides a control method for a converter. The converter includes switching tubes. The control method includes: obtaining the real-time input voltage and real-time output voltage of the converter; determining the real-time closed-loop control output value corresponding to the converter according to the real-time input voltage, the real-time output voltage, and a preset closed-loop control algorithm; determining the real-time control strategy of the switching tubes from at least three preset control strategies according to the real-time closed-loop control output value; and controlling the switching tubes according to the real-time control strategy.

[0006] In this application, compared with the prior art, the existing intermittent control belongs to open-loop control, which leads to poor control accuracy; the real-time closed-loop control output value is determined by using the real-time input voltage and real-time output voltage, and through this real-time closed-loop control output value, the closed-loop control of the switching tubes is realized, and the control accuracy is improved compared with open-loop control. Moreover, through the real-time closed-loop control output value, seamless switching is performed among at least three preset control strategies, and a stable voltage can be output when the load changes. In addition, the control strategy corresponding to the closed-loop control is relatively simple (for example, there is no high requirement for the threshold selection of the switching wave of the switching tubes), and the efficiency of the voltage stabilization control is relatively high, thereby realizing high-efficiency voltage stabilization control.

[0007] As a possible implementation manner, the at least three preset control strategies include at least three of a pulse frequency modulation control strategy, a pulse width modulation control strategy, a pulse density modulation control strategy, and a pulse phase modulation control strategy.

[0008] In this application, the pulse frequency modulation control strategy adjusts the output voltage by adjusting the switching frequency; the pulse width modulation control strategy reduces the output voltage by adjusting the duty cycle of the pulse output; the pulse density modulation control strategy reduces the output voltage by changing the density of the pulse output; the pulse phase modulation control strategy changes the output gain by changing the phase shift angle; by flexibly and smoothly switching the output value through real-time closed-loop control among these control strategies, efficient and high-precision voltage stabilization control can be achieved.

[0009] As a possible implementation, the converter is an isolated resonant DC converter. Determining the real-time control strategy of the switching tube from at least three preset control strategies according to the real-time closed-loop control output value includes: if the real-time closed-loop control output value is greater than or equal to a first preset value, determining the real-time control strategy as the pulse frequency modulation control strategy; if the real-time closed-loop control output value is less than the first preset value and greater than a second preset value, determining the real-time control strategy as the pulse width modulation control strategy; the first preset value is greater than the second preset value; if the real-time closed-loop control output value is less than or equal to the second preset value, determining the real-time control strategy as the pulse density modulation control strategy.

[0010] In this application, for an isolated resonant DC converter, when the real-time closed-loop control output value is different, it smoothly switches among the three control strategies of pulse frequency modulation control strategy, pulse width modulation control strategy, and pulse density modulation control strategy. When the load changes, it can maintain a stable output voltage. For example: first, adjust the output voltage through the pulse frequency modulation control strategy. When the output voltage needs to be further reduced, then use the pulse width modulation control strategy to reduce the output voltage; finally, when it is necessary to turn off the wave, use the pulse density modulation control strategy to achieve turning off the wave; the output voltage changes smoothly during the entire control process.

[0011] As a possible implementation, when the real-time control strategy is the pulse frequency modulation control strategy, controlling the switching tube according to the real-time control strategy includes: modulating the switching frequency of the switching tube to the reciprocal of the real-time closed-loop control output value; modulating the duty cycle of the switching tube to a first preset duty cycle.

[0012] In this application, in the pulse frequency modulation control strategy, the adjustment of the output voltage is achieved through the modulation of the switching frequency and the modulation of the duty cycle.

[0013] As a possible implementation, the real-time control strategy is the pulse width modulation control strategy, and controlling the switching tube according to the real-time control strategy includes: modulating the switching frequency of the switching tube to the reciprocal of a first preset value; modulating the duty cycle of the switching tube according to the real-time closed-loop control output value and the first preset value.

[0014] In the present application, in the pulse width modulation control strategy, the output voltage is reduced by modulating the switching frequency and the duty cycle.

[0015] As a possible implementation, the real-time control strategy is the pulse density modulation control strategy; controlling the switching tube according to the real-time control strategy includes: if the real-time closed-loop control output value is equal to a second preset value, modulating the switching frequency of the switching tube to the reciprocal of a first preset value; modulating the duty cycle of the switching tube to a second preset duty cycle; if the real-time closed-loop control output value is less than the second preset value, modulating the duty cycle of the switching tube to 0.

[0016] In the present application, in the pulse density modulation control strategy, if no wave-off is required (i.e., the real-time closed-loop control output value is equal to the second preset value), the output voltage is further reduced by modulating the switching frequency; if wave-off is required (i.e., the real-time closed-loop control output value is less than the second preset value), wave-off is achieved by modulating the duty cycle to 0.

[0017] As a possible implementation, the converter is a phase-shifted full-bridge converter, and determining the real-time control strategy of the switching tube of the converter from at least three preset control strategies according to the real-time closed-loop control output value includes: if the real-time closed-loop control output value is less than a third preset value, determining the real-time control strategy as the pulse phase modulation control strategy; if the real-time closed-loop control output value is greater than the third preset value, determining the real-time control strategy as the pulse width modulation control strategy; if the real-time closed-loop control output value satisfies a preset relationship with the third preset value, determining the real-time control strategy as the pulse density modulation control strategy.

[0018] In the present application, for a phase-shifted full-bridge converter, when the real-time closed-loop control output value is different, smooth switching is performed among the three control strategies of the pulse phase modulation control strategy, the pulse width modulation control strategy, and the pulse density modulation control strategy. When the load changes, a stable output voltage can be maintained. For example: first, the output voltage is adjusted by the pulse phase adjustment control strategy. When the output voltage needs to be further reduced, the pulse width modulation control strategy is used to reduce the output voltage; finally, when wave-off is required, the pulse density modulation control strategy is used to achieve wave-off; the output voltage changes smoothly during the entire control process.

[0019] As a possible implementation manner, the real-time control strategy is the pulse phase modulation control strategy, and controlling the switching tube according to the real-time control strategy includes: adjusting the phase shift angle of the pulse waveforms between two arms of the phase-shifted full-bridge converter; modulating the duty cycle of the switching tube to a third preset duty cycle and modulating the switching frequency of the switching tube to a preset frequency.

[0020] In the present application, in the pulse phase modulation control strategy, the adjustment of the output voltage is achieved through the modulation of the phase shift angle and the duty cycle.

[0021] As a possible implementation manner, the real-time control strategy is the pulse width modulation control strategy, and controlling the switching tube according to the real-time control strategy includes: adjusting the phase shift angle of the pulse waveforms between two arms of the phase-shifted full-bridge converter to the third preset value; modulating the duty cycle of the switching tube according to the third preset value and the real-time closed-loop control output value.

[0022] In the present application, in the pulse width modulation control strategy, the reduction of the output voltage can be achieved through the modulation of the phase shift angle and the duty cycle.

[0023] As a possible implementation manner, the real-time control strategy is the pulse density modulation control strategy, and controlling the switching tube according to the real-time control strategy includes: adjusting the phase shift angle of the pulse waveforms between two arms of the phase-shifted full-bridge converter to the third preset value, and modulating the duty cycle of the switching tube to a fourth preset duty cycle; or modulating the duty cycle of the switching tube to 0.

[0024] In the present application, in the pulse density modulation control strategy, the phase shift angle and the fixed duty cycle can be adjusted, that is, non-switching wave processing; or the duty cycle can be modulated to 0, that is, switching wave processing.

[0025] As a possible implementation manner, controlling the switching tube according to the real-time control strategy includes: modulating the parameters of the switching tube according to the real-time control strategy; the parameters of the switching tube include at least one of the switching frequency, the duty cycle, and the phase shift angle.

[0026] In the present application, based on different real-time control strategies, at least one of the switching frequency, the duty cycle, and the phase shift angle of the switching tube can be modulated to achieve the control of the output voltage.

[0027] In a second aspect, the present application provides a control device for a converter. The converter includes a switching tube, and the control device includes various functional modules for implementing the control method of the converter described in the first aspect and any possible implementation manner of the first aspect.

[0028] In this application, compared with the prior art, the existing intermittent control belongs to open-loop control, which leads to poor control accuracy. By using the real-time input voltage and the real-time output voltage to determine the real-time closed-loop control output value, and through this real-time closed-loop control output value, the closed-loop control of the switching tube is realized. Compared with open-loop control, the control accuracy is improved. Moreover, through the real-time closed-loop control output value, seamless switching is performed among at least three preset control strategies, and a stable voltage can be output when the load changes. In addition, the control strategy corresponding to the closed-loop control is relatively simple (for example, there is no high requirement for the threshold selection of the switching wave of the switching tube), and the efficiency of the voltage stabilization control is relatively high, thus realizing efficient voltage stabilization control.

[0029] In a third aspect, this application provides a readable storage medium, on which a computer program is stored. When the computer program is run by a computer, it executes the control method of the converter as described in the first aspect and any possible implementation manner of the first aspect.

[0030] In this application, compared with the prior art, the existing intermittent control belongs to open-loop control, which leads to poor control accuracy. By using the real-time input voltage and the real-time output voltage to determine the real-time closed-loop control output value, and through this real-time closed-loop control output value, the closed-loop control of the switching tube is realized. Compared with open-loop control, the control accuracy is improved. Moreover, through the real-time closed-loop control output value, seamless switching is performed among at least three preset control strategies, and a stable voltage can be output when the load changes. In addition, the control strategy corresponding to the closed-loop control is relatively simple (for example, there is no high requirement for the threshold selection of the switching wave of the switching tube), and the efficiency of the voltage stabilization control is relatively high, thus realizing efficient voltage stabilization control. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of this application, the following will briefly introduce the drawings required to be used in the embodiments of this application. Obviously, the following described drawings are only some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained according to the drawings without creative efforts.

[0032] Figure 1 It is a schematic diagram of the connection relationship between a converter and a controller disclosed in an embodiment of this application;

[0033] Figure 2 It is a flowchart of the control method of the converter disclosed in an embodiment of this application;

[0034] Figure 3 It is a structural block diagram of the functional modules of the control device of the converter disclosed in an embodiment of this application;

[0035] In the accompanying drawings, the drawings are not drawn to actual scale. Detailed implementation manners

[0036] The following further describes the implementation manners of the present application in conjunction with the accompanying drawings and embodiments. The following detailed description of the embodiments and the accompanying drawings are used to exemplarily illustrate the principle of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0037] In the description of the present application, it should be noted that unless otherwise stated, the meaning of "a plurality" is two or more; the orientation or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range.

[0038] The orientation terms appearing in the following description are all the directions shown in the drawings, and do not limit the specific structure of the present application. In the description of the present application, it should also be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0039] The control method of the converter provided by the embodiment of the present application can be applied to the controller of the converter. For the convenience of understanding, please refer to Figure 1 , which is a schematic diagram of the converter and the controller. In the controller, it includes a voltage sampling module, a closed-loop controller, and a switching tube control module. The converter includes switching tubes. In different converters, the number and connection manner of the switching tubes are different. The converter can be: an isolated resonant conversion controller (i.e., a CLLLC converter); a phase-shifted full-bridge controller, i.e., a PSHB (Phase Bridge) converter.

[0040] The converter can be applied to various charging devices to convert the signals sent by the signal source (such as a battery) of the charging device. The charging device can be, for example, a DC charging pile, an intelligent charging pile, etc.

[0041] Among them, the voltage sampling module is connected to the converter and is used to collect the real-time input voltage and real-time output voltage of the converter. The closed-loop controller is connected to the voltage sampling module and is used to determine the closed-loop control strategy. The switching tube control module is respectively connected to the closed-loop controller and the switching tube of the converter and is used to control the switching tube according to the closed-loop control strategy determined by the closed-loop controller; the switching tube control module can be understood as the drive of the converter.

[0042] In the embodiment of the present application, the closed-loop controller can be a PID controller (Proportion Integration Differentiation), and the PID controller is composed of a proportional unit P, an integral unit I, and a differential unit D; the closed-loop control algorithm corresponding to the PID controller is the PID control algorithm. The closed-loop controller can also be other controllers, which are not limited herein.

[0043] Based on the above introduction of the application scenario, please refer to Figure 2 , which is the flowchart of the control method of the converter provided by the embodiment of the present application. The control method includes:

[0044] Step 210: Obtain the real-time input voltage and real-time output voltage of the converter.

[0045] Step 220: Determine the real-time closed-loop control output value corresponding to the converter according to the real-time input voltage, real-time output voltage, and the preset closed-loop control algorithm.

[0046] Step 230: Determine the real-time control strategy of the switching tube from at least three preset control strategies according to the real-time closed-loop control output value.

[0047] Step 240: Control the switching tube according to the real-time control strategy.

[0048] In the embodiment of the present application, compared with the prior art, the existing intermittent control belongs to open-loop control, which leads to poor control accuracy; the real-time closed-loop control output value is determined by using the real-time input voltage and real-time output voltage, and through this real-time closed-loop control output value, the closed-loop control of the switching tube is realized. Compared with open-loop control, the control accuracy is improved. And, through the real-time closed-loop control output value, seamless switching is performed among at least three preset control strategies, and a stable voltage can be output when the load changes. In addition, the control strategy corresponding to the closed-loop control is relatively simple (for example, there is no high requirement for the threshold selection of the switching wave of the switching tube), and the efficiency of voltage stabilization control is relatively high, thereby realizing efficient voltage stabilization control.

[0049] Next, the detailed implementation manners of steps 210 - 240 will be introduced.

[0050] In step 210, the controller can obtain the real-time input voltage and real-time output voltage of the converter through the voltage sampling module. Among them, the real-time output voltage can be the sampled voltage on the output side of the converter; the real-time input voltage can be the reference voltage on the input side of the converter.

[0051] In step 220, the controller can perform operations on the real-time input voltage and real-time output voltage through the built-in closed-loop control algorithm (i.e., the preset closed-loop control algorithm) in the closed-loop controller to determine the real-time closed-loop control output value.

[0052] It can be understood that different closed-loop controllers correspond to different closed-loop control algorithms. For example, the PID closed-loop controller corresponds to the PID control algorithm. In the embodiments of the present application, if the PID control algorithm is adopted, the dimension of the finally determined real-time closed-loop control output value is time, which is defined as PID.out here.

[0053] In step 230, at least three preset control strategies are at least three of the pulse frequency modulation control strategy, pulse width modulation control strategy, pulse density modulation control strategy, and pulse phase modulation control strategy.

[0054] The pulse frequency modulation control strategy, that is, the PFM (Pulse Frequency Modulation) control strategy, can change the output gain of the converter by adjusting the switching frequency of the switching tube. Output gain = real-time output voltage / real-time input voltage; the higher the switching frequency, the smaller the output gain; therefore, when modulating the switching frequency, the output gain changes accordingly, and the real-time output voltage also changes correspondingly.

[0055] The pulse width modulation control strategy, that is, the PWM (Pulse Width Modulation) control strategy, can reduce the output voltage by adjusting the duty cycle of the pulse output; in this control strategy, the switching frequency can be fixed, and the duty cycle can be within a fixed range.

[0056] The pulse density modulation control strategy, that is, the PDM (Pulse Density Modulation) control strategy, can further adjust (decrease) the output voltage by adjusting the density of the pulse output. The density of the pulse output can also be understood as the number of pulse outputs; in this control strategy, the switching frequency can be fixed, and the duty cycle can be a fixed value.

[0057] The pulse phase modulation control strategy, i.e., the PPM (Pulse Phase Modulation) control strategy, can change the output gain by adjusting the phase shift angle between the two arms of the converter; the larger the phase shift angle, the smaller the output gain; in this control strategy, the duty cycle can be fixed.

[0058] In the embodiments of the present application, by flexibly and smoothly switching the output value in at least three of the above four control strategies through real-time closed-loop control, efficient and high-precision voltage regulation control can be achieved.

[0059] As can be seen from the introduction of each control strategy, each control strategy corresponds to a different parameter control method. Therefore, as an optional implementation manner, step 240 includes: modulating the parameters of the switching tube according to the real-time control strategy; the parameters of the switching tube include at least one of the switching frequency, duty cycle, and phase shift angle.

[0060] It can be understood that different converters have different circuit structures. Therefore, for different converters, the implementation manner of determining the control strategy and the implementation of the control strategy are also different. In the embodiments of the present application, the determination method of the control strategy (i.e., the implementation manner of step 230) and the implementation method of the control strategy (i.e., the implementation manner of step 240) for the isolated resonant DC converter and the phase-shifted full-bridge converter are introduced separately.

[0061] As an optional implementation manner, the converter is an isolated resonant DC converter; at this time, step 230 includes: if the real-time closed-loop control output value is greater than or equal to the first preset value, determining the real-time control strategy as the pulse frequency modulation control strategy; if the real-time closed-loop control output value is less than the first preset value and greater than the second preset value, determining the real-time control strategy as the pulse width modulation control strategy; the first preset value is greater than the second preset value; if the real-time closed-loop control output value is less than or equal to the second preset value, determining the real-time control strategy as the pulse density modulation control strategy.

[0062] Among them, the first preset value can be the minimum period for the switching tube control module to perform drive control (i.e., the reciprocal of the maximum switching frequency). It can be understood that due to hardware condition limitations, the switching frequency of the switching tube cannot be infinitely large and there is a maximum value. In practical applications, the first preset value can be determined according to the hardware situation (such as the hardware drive circuit or the switching tube), and the specific value is not limited in the embodiments of the present application. Here, the first preset value can be defined as Tmin.

[0063] The first preset value is greater than the second preset value. As an alternative implementation, the second preset value can be: A*Tmin, where the value range of A is 0-1. For example, the value of A can be 0.2. In practical applications, the specific value of A can be determined according to the hardware conditions, which is not limited in the embodiments of the present application.

[0064] In the embodiments of the present application, for an isolated resonant DC converter, when the real-time closed-loop control output value is different, it smoothly switches among the three control strategies of pulse frequency modulation control strategy, pulse width modulation control strategy, and pulse density modulation control strategy. When the load changes, it can maintain a stable output voltage. For example, first, the output voltage is adjusted by the pulse frequency modulation control strategy. When the output voltage needs to be further reduced, the pulse width modulation control strategy is used to reduce the output voltage. Finally, when wave-off is required, the pulse density modulation control strategy is used to achieve wave-off; the output voltage changes smoothly during the entire control process.

[0065] For example, when PID.out is greater than or equal to Tmin, at this time, the switch tube control module controls the switch tube through the pulse frequency modulation control strategy; when PID.out is less than Tmin and greater than A*Tmin, at this time, the switch tube control module controls the switch tube through the pulse width modulation control strategy; when PID.out is less than or equal to A*Tmin, at this time, the switch tube control module controls the switch tube through the pulse density modulation control strategy.

[0066] As an alternative implementation, when the real-time control strategy is the pulse frequency modulation control strategy, step 240 includes: modulating the switching frequency of the switch tube to the reciprocal of the real-time closed-loop control output value; modulating the duty cycle of the switch tube to the first preset duty cycle.

[0067] Among them, the first preset duty cycle can be set according to the actual application scenario, which is not limited in the embodiments of the present application. By way of example, the first preset duty cycle can be 50%.

[0068] Correspondingly, the switching frequency of the switch tube is: 1 / Tmin, and this switching frequency can be understood as the maximum switching frequency.

[0069] It can be seen that in the pulse frequency modulation control strategy, by modulating the switching frequency and fixing the duty cycle, the adjustment of the output voltage is achieved. The higher the switching frequency, the smaller the gain.

[0070] As an alternative implementation, when the real-time control strategy is the pulse width modulation control strategy, step 240 includes: modulating the switching frequency of the switch tube to the reciprocal of the first preset value; modulating the duty cycle of the switch tube according to the real-time closed-loop control output value and the first preset value.

[0071] Among them, the relationship between the duty cycle and the real-time closed-loop control output value and the first preset value can be: duty cycle = (PID.out * B) / Tmin. The value range of B is 0 - 1. For example, the value of B can be 0.5. In practical applications, the value of B can be determined according to the value range of the duty cycle of the switching tube. The value range of the duty cycle can be determined according to the actual test waveform. In the embodiment of the present application, the value range of the duty cycle can be 10% - 50%. When the duty cycle is less than 10%, the hardware circuit of the isolated resonant DC converter cannot be turned on.

[0072] Correspondingly, the switching frequency of the switching tube is 1 / Tmin.

[0073] In this control strategy, when the switching frequency of the switching tube is fixed, the smaller the duty cycle, the smaller the output voltage, and thus the reduction of the output voltage can be achieved.

[0074] As an optional implementation manner, when the real-time control strategy is a pulse density modulation control strategy, step 240 includes: if the real-time closed-loop control output value is equal to the second preset value, modulating the switching frequency of the switching tube to the reciprocal of the first preset value; modulating the duty cycle of the switching tube to the second preset duty cycle; if the real-time closed-loop control output value is less than the second preset value, modulating the duty cycle of the switching tube to 0.

[0075] Among them, the second preset duty cycle can be the minimum duty cycle for turning on the converter. For example, the second preset duty cycle can be 10%. Correspondingly, the switching frequency of the switching tube is 1 / Tmin.

[0076] In the pulse density modulation control strategy, there are two cases. One case is that PID.out is equal to A * Tmin. At this time, the switching frequency of the switching tube is modulated to the maximum switching frequency, and the second duty cycle ensures that the converter can be turned on, which can play a role in reducing the output voltage. The other case is that PID.out is less than A * Tmin. At this time, the duty cycle can be controlled to 0, that is, directly turn off the wave. Directly turning off the wave will cause the output voltage to continue to drop. At this time, the controller will continue to make a judgment. For example, it may adopt the pulse frequency modulation control strategy again.

[0077] The pulse density modulation control strategy can be understood as changing the density of pulse output, that is, changing the number of pulse outputs. When the switching frequency is fixed and the duty cycle is fixed, the fewer the number of pulse outputs, the smaller the output voltage, and thus the adjustment of the output voltage is realized.

[0078] For the above three control strategies, when it is necessary to reduce the output voltage, the controller generally first adopts the pulse frequency modulation control strategy. When the switching frequency reaches the maximum switching frequency, the switching frequency is fixed at the maximum switching frequency, and at this time, the pulse width modulation control strategy is adopted. When the duty cycle reaches the minimum value (i.e., the second duty cycle), the switching frequency is fixed at the maximum switching frequency, the duty cycle is fixed at the minimum value, and the pulse density modulation control strategy is adopted.

[0079] In practical applications, for example: assume that the converter is applied to a DC charging pile. When the DC charging pile charges an electric vehicle, insulation detection needs to be carried out first. In this working condition, the DC charging pile starts up without load, and usually the lowest output voltage is 250V. At this time, the pulse frequency modulation control strategy can be adopted first to raise the switching frequency to the maximum frequency (such as 390kHz) and keep it to obtain the minimum output gain of the DC charging pile. However, at this time, the reference voltage (i.e., the input-side voltage) is lower than the actual sampled voltage (i.e., the output-side voltage). At this time, the DC charging pile can further reduce the voltage by adopting the pulse width modulation control strategy and the pulse density modulation control strategy through the judgment of the closed-loop control output value to achieve hybrid modulation to meet the requirement that the output voltage of the device is at least 250V.

[0080] Therefore, when the output voltage of the isolated resonant DC converter is relatively low or under light load conditions, such as when the DC charging pile charges a vehicle and the battery voltage is relatively low or at the end of charging, the hybrid control strategy of pulse frequency modulation + pulse width modulation + pulse density modulation can be adopted to achieve stable voltage output.

[0081] As another alternative implementation, the converter is a phase-shifted full-bridge converter. At this time, step 230 includes: if the real-time closed-loop control output value is less than the third preset value, determining that the real-time control strategy is the pulse phase modulation control strategy; if the real-time closed-loop control output value is greater than the third preset value, determining that the real-time control strategy is the pulse width modulation control strategy; if the real-time closed-loop control output value satisfies a preset relationship with the third preset value, determining that the real-time control strategy is the pulse density modulation control strategy.

[0082] Among them, the third preset value is the maximum phase shift angle of the switching tubes of the phase-shifted full-bridge converter. Assume it is defined as: PSHmax, and it can be expressed as: the phase shift angle corresponding to the pulse Tprd / 2; Tprd is the pulse waveform period, which is a fixed value. Therefore, the specific value of the third preset value depends on the hardware drive circuit and the switching tubes, and the specific value is not limited in the embodiments of the present application.

[0083] As an alternative embodiment, when the pulse density modulation control strategy is adopted, Tprd / 2 - (PID.out - PSHmax) is equal to or less than (C * Tprd). Therefore, the preset relationship can be expressed as: PID.out is equal to or greater than Tprd / 2 - C * Tprd + PSHmax. Wherein, the value of C can be preset according to the actual hardware circuit conditions, and the value range is 0 - 1. For example, its value can be 0.1.

[0084] For example, when the PID.out value is less than PSHmax (i.e., the maximum phase shift angle), the pulse phase modulation control strategy is adopted; when the PID.out value is greater than PSHmax, the pulse width modulation control strategy is adopted; when PID.out = Tprd / 2 - C * Tprd + PSHmax, the pulse density modulation control strategy is adopted.

[0085] It can be seen that for the phase - shifted full - bridge converter, when the real - time closed - loop control output value is different, it smoothly switches among the three control strategies of the pulse phase modulation control strategy, the pulse width modulation control strategy, and the pulse density modulation control strategy. When the load changes, it can maintain a stable output voltage. For example: first, adjust the output voltage through the pulse phase adjustment control strategy. When the output voltage needs to be further reduced, then use the pulse width modulation control strategy to reduce the output voltage; finally, when it is necessary to turn off the wave, use the pulse density modulation control strategy to achieve turning off the wave; the output voltage changes smoothly during the whole control process.

[0086] As an alternative embodiment, if the real - time control strategy is the pulse phase modulation control strategy, then step 240 includes: adjusting the phase - shift angle of the pulse waveforms between two arms of the phase - shifted full - bridge converter; modulating the duty cycle of the switching tube to a third preset duty cycle and modulating the switching frequency of the switching tube to a preset frequency.

[0087] Wherein, the third preset duty cycle can be the maximum duty cycle of the switching tube, for example: 50%. The preset frequency can be the maximum switching frequency of the switching tube or other frequencies. In practical applications, the third preset duty cycle and the preset frequency can be determined according to the specific application scenario (such as in combination with the actual waveform situation), and are not limited in the embodiments of the present application.

[0088] In the pulse phase modulation control strategy, the output gain is changed by adjusting the phase - shift angle of the pulse waveforms between two arms of the phase - shifted full - bridge converter. The larger the phase - shift angle, the smaller the output gain.

[0089] When modulating the phase - shift angle, the phase - shift angle can be gradually increased. When the phase - shift angle increases, PID.out will also change correspondingly, and the controller will change the control strategy of the switching tube accordingly. Therefore, the modulation of the phase - shift angle can be carried out without setting the target value of the phase - shift angle modulation.

[0090] As an alternative implementation, if the real-time control strategy is a pulse phase width modulation control strategy, step 240 at this time includes: adjusting the phase shift angle of the pulse waveforms between two arms in the phase-shifted full-bridge converter to a third preset value; modulating the duty cycle of the switching tubes according to the third preset value and the real-time closed-loop control output value.

[0091] Wherein, the third preset value is the PSHmax (i.e., the maximum phase shift angle) introduced in the foregoing embodiment. The modulation method of the duty cycle can be: modulating the duty cycle to Tprd / 2 - (PID.out - PSHmax).

[0092] When modulating the duty cycle, similar to the isolated resonant DC converter, when the duty cycle is less than the minimum duty cycle, the hardware circuit of the phase-shifted full-bridge converter may not be able to conduct. Therefore, Tprd / 2 - (PID.out - PSHmax) needs to be greater than the minimum duty cycle.

[0093] In the pulse width modulation control strategy, the output voltage is adjusted by modulating the duty cycle of the pulse output. When the phase shift angle is fixed at the maximum phase shift angle, the smaller the duty cycle, the smaller the output voltage. The adjustment range of the duty cycle can be: 10% to 50%.

[0094] As an alternative implementation, if the real-time control strategy is a pulse density modulation control strategy, step 240 at this time includes: adjusting the phase shift angle of the pulse waveforms between two arms in the phase-shifted full-bridge converter to a third preset value, and modulating the duty cycle of the switching tubes to a fourth preset duty cycle; or modulating the duty cycle of the switching tubes to 0.

[0095] Wherein, the fourth preset duty cycle can be the minimum duty cycle in the foregoing embodiment.

[0096] If Tprd / 2 - (PID.out - PSHmax) is equal to (C * Tprd), the phase shift angle can be fixed at PSHmax and the duty cycle can be fixed at the fourth preset duty cycle. If Tprd / 2 - (PID.out - PSHmax) is less than (C * Tprd), the duty cycle is modulated to 0, that is, directly turn off the wave. Directly turning off the wave will cause the output voltage to continue to decrease, and the controller continues to judge the real-time closed-loop control output value to switch the control strategy.

[0097] In the pulse density modulation control strategy, the phase shift angle can be adjusted and the duty cycle can be fixed, that is, non-turn-off wave processing; or the duty cycle can be modulated to 0, that is, turn-off wave processing. Its modulation method is to change the density of the pulse output, which can also be understood as changing the number of pulse outputs. When the switching frequency is fixed and the duty cycle is fixed, the fewer the number of pulse outputs, the smaller the output voltage, thereby realizing the control of the output voltage.

[0098] Therefore, in the embodiments of the present application, in addition to the aforementioned hybrid control strategy, a hybrid control strategy of pulse phase modulation + pulse width modulation + pulse density modulation can also be adopted to achieve regulated voltage output.

[0099] An acquisition module 310 is configured to acquire the real-time input voltage and the real-time output voltage of the converter; a control module 320 is configured to: determine a real-time closed-loop control output value corresponding to the converter according to the real-time input voltage, the real-time output voltage, and a preset closed-loop control algorithm; determine a real-time control strategy of the switching tube from at least three preset control strategies according to the real-time closed-loop control output value; and control the switching tube according to the real-time control strategy.

[0100] In the embodiments of the present application, the control module 320 is specifically configured to: if the real-time closed-loop control output value is greater than or equal to a first preset value, determine that the real-time control strategy is the pulse frequency modulation control strategy; if the real-time closed-loop control output value is less than the first preset value and greater than a second preset value, determine that the real-time control strategy is the pulse width modulation control strategy; the first preset value is greater than the second preset value; if the real-time closed-loop control output value is less than or equal to the second preset value, determine that the real-time control strategy is the pulse density modulation control strategy.

[0101] In the embodiments of the present application, the control module 320 is further specifically configured to: modulate the switching frequency of the switching tube to the reciprocal of the real-time closed-loop control output value; and modulate the duty cycle of the switching tube to a first preset duty cycle.

[0102] In the embodiments of the present application, the control module 320 is further specifically configured to: modulate the switching frequency of the switching tube to the reciprocal of a first preset value; and modulate the duty cycle of the switching tube according to the real-time closed-loop control output value and the first preset value.

[0103] In the embodiments of the present application, the control module 320 is further specifically configured to: if the real-time closed-loop control output value is equal to the second preset value, modulate the switching frequency of the switching tube to the reciprocal of the first preset value; modulate the duty cycle of the switching tube to a second preset duty cycle; if the real-time closed-loop control output value is less than the second preset value, modulate the duty cycle of the switching tube to 0.

[0104] In an embodiment of the present application, the control module 320 is further specifically configured to: if the real-time closed-loop control output value is less than a third preset value, determine that the real-time control strategy is the pulse phase modulation control strategy; if the real-time closed-loop control output value is greater than the third preset value, determine that the real-time control strategy is the pulse width modulation control strategy; if the real-time closed-loop control output value satisfies a preset relationship with the third preset value, determine that the real-time control strategy is the pulse density modulation control strategy.

[0105] In an embodiment of the present application, the control module 320 is further specifically configured to: adjust the phase shift angle of the pulse waveforms between two arms of the phase-shifted full-bridge converter; modulate the duty cycle of the switching tube to a third preset duty cycle and modulate the switching frequency of the switching tube to a preset frequency.

[0106] In an embodiment of the present application, the control module 320 is further specifically configured to: adjust the phase shift angle of the pulse waveforms between two arms of the phase-shifted full-bridge converter to the third preset value; modulate the duty cycle of the switching tube according to the third preset value and the real-time closed-loop control output value.

[0107] In an embodiment of the present application, the control module 320 is further specifically configured to: adjust the phase shift angle of the pulse waveforms between two arms of the phase-shifted full-bridge converter to the third preset value, and modulate the duty cycle of the switching tube to a fourth preset duty cycle; or modulate the duty cycle of the switching tube to 0.

[0108] In an embodiment of the present application, the control module 320 is further specifically configured to: modulate the parameters of the switching tube according to the real-time control strategy; the parameters of the switching tube include at least one of a switching frequency, a duty cycle, and a phase shift angle.

[0109] The control device 300 of the converter corresponds to the control method of the converter in the foregoing embodiment, and each module thereof corresponds to each step of the control method of the converter one by one. Therefore, the implementation manners of each module refer to the implementation manners of each step in the foregoing embodiment and will not be repeated here.

[0110] Based on the same inventive concept, an embodiment of the present application further provides a readable storage medium, on which a computer program is stored. When the computer program is run by a computer, it executes the control method of the converter in the foregoing embodiment.

[0111] Although the present application has been described with reference to preferred embodiments, various modifications thereof may be made without departing from the scope of the present application, and components thereof may be replaced with equivalents. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any manner. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A control method for a converter, characterized in that, The converter includes a switching tube, and the control method includes: Obtaining the real-time input voltage and the real-time output voltage of the converter; Determining the real-time closed-loop control output value corresponding to the converter according to the real-time input voltage, the real-time output voltage, and a preset closed-loop control algorithm; Determining the real-time control strategy of the switching tube from at least three preset control strategies according to the real-time closed-loop control output value, where the at least three preset control strategies include at least three of a pulse frequency modulation control strategy, a pulse width modulation control strategy, a pulse density modulation control strategy, and a pulse phase modulation control strategy; Controlling the switching tube according to the real-time control strategy; Wherein, the converter is a phase-shifted full-bridge converter, and determining the real-time control strategy of the switching tube of the converter from at least three preset control strategies according to the real-time closed-loop control output value includes: If the real-time closed-loop control output value is less than a third preset value, determining the real-time control strategy as the pulse phase modulation control strategy; If the real-time closed-loop control output value is greater than the third preset value, determining the real-time control strategy as the pulse width modulation control strategy; If the real-time closed-loop control output value satisfies a preset relationship with the third preset value, determining the real-time control strategy as the pulse density modulation control strategy.

2. The control method according to claim 1, wherein When the real-time control strategy is the pulse phase modulation control strategy, controlling the switching tube according to the real-time control strategy includes: Adjusting the phase shift angle of the pulse waveforms between two arms in the phase-shifted full-bridge converter; Modulating the duty cycle of the switching tube to a third preset duty cycle and modulating the switching frequency of the switching tube to a preset frequency.

3. The control method according to claim 1, wherein When the real-time control strategy is the pulse width modulation control strategy, controlling the switching tube according to the real-time control strategy includes: Adjusting the phase shift angle of the pulse waveforms between two arms in the phase-shifted full-bridge converter to the third preset value; Modulating the duty cycle of the switching tube according to the third preset value and the real-time closed-loop control output value.

4. The control method according to claim 1, wherein When the real-time control strategy is the pulse density modulation control strategy, controlling the switching tube according to the real-time control strategy includes: Adjusting the phase shift angle of the pulse waveforms between two arms in the phase-shifted full-bridge converter to the third preset value and modulating the duty cycle of the switching tube to a fourth preset duty cycle; or, Modulating the duty cycle of the switching tube to 0.

5. The control method according to claim 1, wherein Controlling the switching tube according to the real-time control strategy includes: Modulating the parameters of the switching tube according to the real-time control strategy; the parameters of the switching tube include at least one of a switching frequency, a duty cycle, and a phase shift angle.

6. A control device for a converter, characterized in that, The converter includes a switching tube, and the control device includes: An acquisition module for acquiring the real-time input voltage and the real-time output voltage of the converter; A control module for: Determine the real-time closed-loop control output value corresponding to the converter according to the real-time input voltage, the real-time output voltage, and a preset closed-loop control algorithm; determine the real-time control strategy of the switching tube from at least three preset control strategies; control the switching tube according to the real-time control strategy, and the at least three preset control strategies include at least three of pulse frequency modulation control strategy, pulse width modulation control strategy, pulse density modulation control strategy, and pulse phase modulation control strategy; Wherein, the converter is a phase-shifted full-bridge converter, and the control module is specifically configured to: If the real-time closed-loop control output value is less than a third preset value, determine that the real-time control strategy is the pulse phase modulation control strategy; If the real-time closed-loop control output value is greater than the third preset value, determine that the real-time control strategy is the pulse width modulation control strategy; If the real-time closed-loop control output value satisfies a preset relationship with the third preset value, determine that the real-time control strategy is the pulse density modulation control strategy.

7. The control device according to claim 6, characterized in that, When the real-time control strategy is the pulse phase modulation control strategy, the control module is specifically configured to: Adjust the phase shift angle of the pulse waveforms between two arms of the phase-shifted full-bridge converter; Modulate the duty cycle of the switching tube to a third preset duty cycle and modulate the switching frequency of the switching tube to a preset frequency.

8. The control device according to claim 6, characterized in that, When the real-time control strategy is the pulse width modulation control strategy, the control module is specifically configured to: Adjust the phase shift angle of the pulse waveforms between two arms of the phase-shifted full-bridge converter to the third preset value; Modulate the duty cycle of the switching tube according to the third preset value and the real-time closed-loop control output value.

9. The control device according to claim 6, wherein When the real-time control strategy is the pulse density modulation control strategy, the control module is specifically configured to: Adjust the phase shift angle of the pulse waveforms between two arms of the phase-shifted full-bridge converter to the third preset value and modulate the duty cycle of the switching tube to a fourth preset duty cycle; or, Modulate the duty cycle of the switching tube to 0.

10. The control device according to claim 6, characterized in that, The control module is specifically configured to: Modulate the parameters of the switching tube according to the real-time control strategy; the parameters of the switching tube include at least one of switching frequency, duty cycle, and phase shift angle.

11. A readable storage medium, characterized in that, A computer program is stored on the readable storage medium, and when the computer program is run by the computer, it executes the control method of the converter according to any one of claims 1-4.

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