Converter control method, controller and storage medium

Abstract

The invention discloses a converter control method, a controller and a storage medium, and relates to the technical field of power electronics, and the converter control method comprises the steps: determining the current working mode of an AC-DC converter according to the obtained AC voltage and DC voltage of the AC-DC converter; a target modulation parameter meeting a soft switching condition (a condition capable of enabling a switching tube to be switched on or switched off when the voltage or the current of the switching tube is zero) when the AC-DC converter works in a current working mode is calculated, and a switching tube driving signal is generated based on the target modulation parameter, so that the AC-DC converter is controlled. Therefore, the switching tube of the AC-DC converter can be switched on or switched off when the voltage or current of the switching tube is zero, the loss of the switching tube is reduced, the advantage that the zero-voltage switching range can be expanded to a certain extent in the expansion phase shift control method is utilized, and the working efficiency of the AC-DC converter is improved on the whole.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and particularly to a converter control method, a controller, and a storage medium. Background Art

[0002] Currently, the control methods for AC-DC (alternating current - direct current) converters usually include single phase shift (SPS), extended phase shift (EPS), triple phase shift (TPS), etc.; since the extended phase shift control method can, to a certain extent, expand the ZVS (Zero Voltage Switching) range, thereby improving the working efficiency of the converter, this extended phase shift control method is widely used in the control of DAB (Dual Active Bridge Converter) converters.

[0003] Since the working state of the AC-DC converter is affected by various factors such as input voltage and output load, and the extended phase shift control method depends on specific working conditions to achieve optimal performance, if this extended phase shift control method is applied to the control of the AC-DC converter, when the load or input voltage fluctuates, the extended phase shift angle in the extended phase shift control method is no longer applicable, but instead reduces the working efficiency of the AC-DC converter. Summary of the Invention

[0004] The main purpose of this application is to provide a converter control method, a controller, and a storage medium, aiming to solve the technical problem of low working efficiency of the AC-DC converter.

[0005] To achieve the above purpose, this application proposes a converter control method, and the method includes:

[0006] Determine the current working mode of the AC-DC converter according to the obtained AC voltage and DC voltage of the AC-DC converter;

[0007] Calculate the target modulation parameters that meet the soft-switching conditions for the AC-DC converter to work in the current working mode, where the target modulation parameters include a target phase shift angle, a first duty cycle of each switching tube in the AC-side H-bridge, and a second duty cycle of the output voltage at the midpoint of the DC-side H-bridge arm, and the phase shift angle is the phase difference between the output voltages at the midpoint of the corresponding arms of the AC-side H-bridge and the DC-side H-bridge;

[0008] Generate a switching tube drive signal based on the target modulation parameters to achieve the control of the converter.

[0009] In one embodiment, the step of determining the current operating mode of the AC-DC converter according to the obtained AC voltage and DC voltage of the AC-DC converter includes:

[0010] Determine the current operating mode of the AC-DC converter according to the AC voltage, DC voltage, AC current reference value, and the soft-switching condition when the AC-DC converter operates in a preset operating mode.

[0011] In one embodiment, the operating modes of the AC-DC converter are divided into a first mode and a second mode; when the preset operating mode is the first mode, the step of determining the current operating mode of the AC-DC converter according to the AC voltage, DC voltage, AC current reference value, and the soft-switching condition when the AC-DC converter operates in the preset operating mode includes:

[0012] Calculate a first phase-shift angle that satisfies the soft-switching condition when the AC-DC converter operates in the first mode and a third duty ratio of the output voltage at the midpoint of the DC-side H-bridge arm according to the AC voltage, DC voltage, and AC current reference value.

[0013] Judge whether the current operating mode of the AC-DC converter is the first mode according to the first phase-shift angle, the third duty ratio, and a preset mode division condition, where the preset mode division condition is determined according to the magnitude relationship between the phase-shift angle and the duty ratio of the output voltage at the midpoint of the DC-side H-bridge arm.

[0014] When the current operating mode is not the first mode, determine that the current operating mode of the AC-DC converter is the second mode.

[0015] In one embodiment, when the current operating mode is the first mode, the step of calculating the target modulation parameter that satisfies the soft-switching condition when the AC-DC converter operates in the current operating mode includes:

[0016] Calculate the fourth duty ratio of each switch tube in the AC-side H-bridge according to the first phase-shift angle, the second duty ratio, and a preset correlation relationship between the phase-shift angle and the duty ratio.

[0017] Take the first phase-shift angle, the third duty ratio, and the fourth duty ratio as the first modulation parameter.

[0018] In one embodiment, when the current operating mode is the second mode, the target modulation parameter includes a second modulation parameter, and the step of calculating the target modulation parameter that satisfies the soft-switching condition when the AC-DC converter operates in the current operating mode includes:

[0019] Calculate the phase-shift angle range of the AC-DC converter operating in the second mode according to the reference values of the AC voltage, DC voltage, AC current, and the maximum and minimum duty cycles of the output voltage at the midpoint of the H-bridge arm on the DC side;

[0020] Calculate the second modulation parameter that satisfies the soft-switching condition for the AC-DC converter operating in the second mode according to the reference values of the AC voltage, DC voltage, AC current, and the phase-shift angle range;

[0021] In one embodiment, the second modulation parameter includes a second phase-shift angle, a fifth duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side, and a sixth duty cycle of each switch in the H-bridge on the AC side; the step of calculating the second modulation parameter that satisfies the soft-switching condition for the AC-DC converter operating in the second mode according to the reference values of the AC voltage, DC voltage, AC current, and the phase-shift angle range includes:

[0022] Calculate the second phase-shift angle according to the AC voltage, DC voltage, the soft-switching condition for the AC-DC converter operating in the second mode, and the maximum duty cycle of each switch in the H-bridge on the AC side;

[0023] Limit the second phase-shift angle according to the phase-shift angle range to obtain the limited phase-shift angle;

[0024] Calculate the fifth duty cycle according to the limited phase-shift angle and the reference value of the AC current;

[0025] Calculate the sixth duty cycle according to the second phase-shift angle, the fifth duty cycle, and the preset correlation between the phase-shift angle and the duty cycle;

[0026] In one embodiment, the step of generating the switch driving signal based on the target modulation parameter includes:

[0027] Generate the switch driving signal based on the target modulation parameter and the switch driving timing corresponding to the current operating mode;

[0028] In one embodiment, the AC-DC converter is a single-stage bidirectional isolated AC-DC converter.

[0029] In addition, to achieve the above object, the present application also proposes a controller, which includes: a memory, a processor, and a computer program stored on the memory and executable on the processor, and the computer program is configured to implement the steps of the converter control method as described above.

[0030] In addition, to achieve the above object, the present application further provides a storage medium, which is a computer-readable storage medium. A computer program is stored on the storage medium, and when the computer program is executed by a processor, the steps of the converter control method described above are implemented.

[0031] One or more technical solutions proposed by the present application have at least the following technical effects:

[0032] The present application determines the current working mode of the AC-DC converter according to the obtained AC voltage and DC voltage of the AC-DC converter; since the AC voltage and DC voltage of the AC-DC converter are fluctuating, according to the obtained current AC voltage and DC voltage of the AC-DC converter, the current working mode of the AC-DC converter is defined (that is, different AC voltages and DC voltages correspond to different working modes of the AC-DC converter).

[0033] Further, the target modulation parameters that satisfy the soft-switching conditions (conditions that enable the switching tubes to turn on or off when their voltage or current is zero) for the AC-DC converter to operate in the current working mode are calculated, and the switching tube drive signals generated based on the target modulation parameters are used to control the AC-DC converter, so that the switching tubes of the AC-DC converter can turn on or off when their voltage or current is zero, reducing the switching tube losses.

[0034] Moreover, since the target modulation parameters include the target phase-shift angle (the phase difference between the output voltages of the midpoints of the bridge arms corresponding to the AC-side H-bridge and the DC-side H-bridge respectively), the first duty ratios of the switching tubes in the AC-side H-bridge, and the second duty ratio of the output voltage of the midpoint of the DC-side H-bridge arm, the switching tube drive signals generated based on the target modulation parameters utilize the advantage of the extended phase-shift control method that can expand the zero-voltage switching range to a certain extent.

[0035] Based on the above, the present application avoids the problem that the extended phase-shift angle in the extended phase-shift control method is no longer applicable when the load or input voltage fluctuates, and overall improves the working efficiency of the AC-DC converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0037] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0038] Figure 1 It is a schematic flowchart provided for the first embodiment of the converter control method of this application;

[0039] Figure 2 It is a schematic diagram of the scenario provided for the first embodiment of the converter control method of this application;

[0040] Figure 3 It is a schematic flowchart of the brief process of the converter control method provided for the first embodiment of this application;

[0041] Figure 4 It is a schematic diagram of the scenario provided for the second embodiment of the converter control method of this application;

[0042] Figure 5 It is a schematic diagram of the scenario provided for the third embodiment of the converter control method of this application;

[0043] Figure 6 It is a schematic diagram of the structure of the controller in the hardware operating environment involved in the converter control method of this application.

[0044] The realization of the purpose, functional features and advantages of this application will be further described with reference to the embodiments and the accompanying drawings. Specific Embodiments

[0045] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of this application and are not used to limit this application.

[0046] For a better understanding of the technical solutions of this application, the following will be described in detail in combination with the drawings of the specification and specific embodiments.

[0047] Based on this, the embodiments of this application provide a converter control method, referring to Figure 1 , Figure 1 It is a schematic flowchart of the first embodiment of the converter control method of this application.

[0048] In this embodiment, the converter control method includes steps S10 to S30:

[0049] Step S10, determine the current working mode of the AC-DC converter according to the obtained AC voltage and DC voltage of the AC-DC converter;

[0050] It should be noted that the execution subject of the above converter control method can be a controller or a converter control device, etc. The following will be described by taking the controller as an example.

[0051] To solve the above technical problem that when the load or input voltage fluctuates, the extended phase-shift angle in the extended phase-shift control method is no longer applicable and instead reduces the working efficiency of the AC-DC converter, this embodiment aims to dynamically analyze the working mode of the AC-DC converter, calculate the target modulation parameters that meet the soft-switching conditions under different working modes, and specifically implement the converter control under different working modes.

[0052] Specifically, the controller obtains the AC voltage and DC voltage of the AC-DC converter, and determines the current working mode of the AC-DC converter according to the AC voltage and DC voltage of the AC-DC converter. Since the AC voltage and DC voltage of the AC-DC converter are fluctuating, the current working mode of the AC-DC converter is dynamically analyzed according to the obtained current AC voltage and DC voltage of the AC-DC converter.

[0053] It should be noted that when the AC-DC converter is used as a rectifier, the AC voltage and DC voltage obtained by the controller are the input port voltage and output port voltage respectively; when the AC-DC converter is used as an inverter, the AC voltage and DC voltage obtained by the controller are the output port voltage and input port voltage respectively; for the sake of easy understanding, the following takes the AC-DC converter as a rectifier as an example for illustration.

[0054] Specifically, the working mode of the AC-DC converter may include at least two working modes. The working mode of the AC-DC converter is divided according to the specific topology structure and working conditions of the AC-DC converter, that is, the mode division conditions of the working modes of the AC-DC converter with different topology structures and working conditions are different, and the number of working modes obtained by division is also different.

[0055] The above implementation manner of determining the current working mode of the AC-DC converter according to the obtained AC voltage and DC voltage of the AC-DC converter may be: determining according to the pre-set corresponding relationship between different AC voltages and DC voltages and the working modes.

[0056] Among them, the AC-DC converter includes a single-stage bidirectional isolated AC-DC converter and other AC-DC converters with a topology structure similar to that of the single-stage bidirectional isolated AC-DC converter. For the sake of easy understanding, this embodiment takes the single-stage bidirectional isolated AC-DC converter as an example for illustration.

[0057] Specifically, referring to Figure 2, the single-stage bidirectional isolated AC-DC converter includes an AC power supply AC, an inductor L, a high-frequency transformer Tr, an AC-side H-bridge, a DC-side H-bridge, and a DC power supply DC; among them, the turns ratio of the high-frequency transformer Tr is K:1, the AC-side H-bridge includes switching transistors Q1, Q2, Q3, Q4 and switching transistors Q1’, Q2’, Q3’, Q4’, and the DC-side H-bridge includes switching transistors Q5, Q6, Q7, Q8; Figure 2 As shown in it, iL is the inductor current and iac is the AC current.

[0058] Step S20, calculate the target modulation parameters that satisfy the soft-switching conditions for the AC-DC converter to operate in the current operating mode. Among them, the target modulation parameters include the target phase-shift angle, the first duty cycle of each switching transistor in the AC-side H-bridge, and the second duty cycle of the output voltage at the midpoint of the DC-side H-bridge arm. The phase-shift angle is the phase difference between the output voltages at the midpoints of the corresponding arms of the AC-side H-bridge and the DC-side H-bridge;

[0059] It should be noted that the target phase-shift angle φ in the target modulation parameters is the phase difference between Vpri and Vsec. Vpri is the output voltage at the midpoint of the AC-side H-bridge arm, and Vsec is the output voltage at the midpoint of the DC-side H-bridge arm.

[0060] The traditional extended phase-shift control method realizes zero-voltage switching (ZVS) of some switching elements by changing the phase-shift angle, thereby reducing switching losses and improving efficiency; however, in practical applications, the improvement of the soft-switching range by the extended phase-shift control method is limited, and its main limiting factors include the design parameters of the converter (such as transformer leakage inductance, capacitance value, etc.), operating frequency, load conditions, etc.

[0061] In this embodiment, by calculating the target modulation parameters that satisfy the soft-switching conditions for the AC-DC converter to operate in the current operating mode, not only the phase-shift angle, the first duty cycle, and the second duty cycle are changed, but also the phase-shift angle, the first duty cycle, and the second duty cycle that satisfy the soft-switching conditions for the AC-DC converter to operate in different operating modes can be determined.

[0062] Specifically, the specific implementation of calculating the target modulation parameters that satisfy the soft-switching conditions for the AC-DC converter to operate in the current operating mode can be: based on the AC voltage and the DC voltage, and the soft-switching conditions for the AC-DC converter to operate in the current operating mode, calculate the target modulation parameters.

[0063] Step S30, generate switching transistor drive signals based on the target modulation parameters to achieve the control of the converter.

[0064] Further, based on the target modulation parameters that satisfy the soft-switching conditions for the AC-DC converter to operate in the current operating mode, a switching device drive signal is generated, and the AC-DC converter is controlled based on the switching device drive signal. This not only enables the switching devices of the AC-DC converter to be turned on or off when their voltage or current is zero, reducing the losses of the switching devices, but also utilizes the advantage of the extended phase-shift control method that can expand the zero-voltage switching range to a certain extent.

[0065] Specifically, the implementation manner of generating the switching device drive signal based on the target modulation parameters can be: generating the switching device drive signal based on the target modulation parameters and the switching device drive timing corresponding to the current operating mode.

[0066] Among them, the switching device drive timing is the time sequence and logical relationship involved in the process of using PWM (Pulse Width Modulation) technology to control the conduction and cutoff of the switching device. Different switching devices may have different response times and electrical characteristics. Therefore, different switching device drive timings are also correspondingly designed for different modes of the single-stage bidirectional isolated AC-DC converter.

[0067] Generating the switching device drive signal based on the target modulation parameters and the switching device drive timing corresponding to the current operating mode can achieve precise control of the switching devices of the AC-DC converter in different operating modes, reduce the losses of the switching devices of the AC-DC converter, and improve its operating efficiency.

[0068] Compared with the traditional extended phase-shift control method (which usually uses fixed or preset control logic to control the converter), in this embodiment, by dynamically analyzing the operating mode of the AC-DC converter, calculating the target modulation parameters that satisfy the soft-switching conditions in different operating modes, and specifically implementing the converter control in different operating modes, the problem that the extended phase-shift angle in the extended phase-shift control method is no longer applicable when the load or input voltage fluctuates is avoided, and further, the losses of the switching devices of the AC-DC converter are reduced, and the operating efficiency of the AC-DC converter is improved as a whole.

[0069] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar content as that in the above-mentioned first embodiment can be referred to the above introduction and will not be elaborated hereinafter. On this basis, the implementation manner of determining the current operating mode of the AC-DC converter according to the obtained AC voltage and DC voltage of the AC-DC converter can be:

[0070] Determine the current operating mode of the AC-DC converter according to the AC voltage, DC voltage, AC current reference value, and the soft-switching conditions for the AC-DC converter to operate in the preset operating mode.

[0071] In order to accurately analyze the current working mode of the AC-DC converter, in this embodiment, on the basis of considering the AC voltage and the DC voltage, the preset AC current reference value (the standard value set to ensure the normal operation of the device and achieve the expected performance) and the soft-switching conditions when the AC-DC converter operates in the preset working mode are used as the judgment basis to comprehensively analyze the current working mode of the AC-DC converter.

[0072] Among them, the preset working mode can be one of all the working modes of the AC-DC converter.

[0073] Assume that the working mode of the AC-DC converter is divided into a first mode and a second mode, and the first mode and the second mode are obtained according to the preset mode division conditions. Since the preset mode division conditions are determined according to the magnitude relationship between the phase-shift angle and the duty cycle of the output voltage at the midpoint of the DC-side H-bridge arm, the phase-shift angle and the duty cycle of the output voltage at the midpoint of the DC-side H-bridge arm of the AC-DC converter can be calculated based on the AC voltage, the DC voltage, the AC current reference value, and the soft-switching conditions when the AC-DC converter operates in the preset working mode, so as to determine whether the current working mode of the AC-DC converter meets the preset working mode.

[0074] Specifically, referring to Figure 3 , in the case where the preset working mode is the first mode, the implementation manner of determining the current working mode of the AC-DC converter according to the AC voltage, the DC voltage, the AC current reference value, and the soft-switching conditions when the AC-DC converter operates in the preset working mode can be:

[0075] Calculate the first phase-shift angle that satisfies the soft-switching conditions when the AC-DC converter operates in the first mode and the third duty cycle of the output voltage at the midpoint of the DC-side H-bridge arm according to the AC voltage, the DC voltage, and the AC current reference value; judge whether the current working mode of the AC-DC converter is the first mode according to the first phase-shift angle, the third duty cycle, and the preset mode division conditions; when the current working mode is not the first mode, determine that the current working mode of the AC-DC converter is the second mode.

[0076] It should be noted that the preset mode division conditions can be defining the working mode when 0.5*d2 + φ < 0.25 as the first mode and defining the working mode when 0.5*d2 + φ ≥ 0.25 as the second mode. Referring to Figure 3 , among them, the magnitude relationship between the phase-shift angle and the duty cycle of the output voltage at the midpoint of the DC-side H-bridge arm in the preset mode division conditions is set according to the topological structure and the working conditions.

[0077] Specifically, according to the AC voltage, the DC voltage, and the AC current reference value, the implementation method of calculating the first phase shift angle that satisfies the soft switching condition of the AC-DC converter operating in the first mode and the third duty cycle of the DC side H-bridge arm midpoint output voltage may be:

[0078] According to the working principle of AC-DC converter, the average value of AC current in a single PWM cycle theoretically when AC-DC converter works in the first mode is i avr1 With the AC current reference value i ac_ref Matching, we get equation 1: According to the soft switching condition of the AC-DC converter working in the first mode, and the current i at the time when the switch tube is turned off when the AC-DC converter works in the first mode t3 , we get equation 2: Equation 1 and Equation 2 are combined to obtain equation group 1. According to equation group 1, the first phase shift angle that satisfies the soft switching condition of the AC-DC converter operating in the first mode and can match the input current of the AC-DC converter with the AC current reference value and the third duty cycle of the output voltage at the midpoint of the DC side H-bridge arm are calculated.

[0079] Among them, when the AC-DC converter works in the first mode, the theoretical average value of the AC current in a single PWM cycle is i avr1 The expression is:

[0080]

[0081] The current i at the time when the switch is turned off when the AC-DC converter works in the first mode t3 The expression is:

[0082]

[0083] Wherein, T is the PWM switching period, K is the ratio of the number of turns of the primary winding of the high-frequency transformer to the number of turns of the secondary winding, L is the inductance, d1 is the duty cycle of each switch tube in the H-bridge on the AC side, and d2 is the duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side.

[0084] Since the preset mode division condition is determined according to the magnitude relationship between the phase shift angle and the duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side, the first phase shift angle and the third duty cycle are calculated according to the AC voltage, the DC voltage, the AC current reference value and the soft switching condition of the AC-DC converter working in the first mode, and compared with the preset mode division condition, so as to determine whether the current working mode of the AC-DC converter is the first mode.

[0085] For example, when the magnitude relationship between the first phase shift angle and the third duty cycle satisfies 0.5*d2 + φ < 0.25, it can be determined that the current operating mode is the first mode; since the operating modes of the AC-DC converter are only the first mode and the second mode, when the magnitude relationship between the first phase shift angle and the third duty cycle does not satisfy 0.5*d2 + φ < 0.25, it can be determined that the current operating mode is the second mode; that is, when the current operating mode is not the first mode, the current operating mode of the AC-DC converter is determined to be the second mode.

[0086] After determining the current operating mode of the AC-DC converter, the target modulation parameters that satisfy the soft-switching conditions for the AC-DC converter to operate in the current operating mode can be calculated. Specifically, referring to Figure 3 , in the case where the current operating mode is the first mode, the implementation manner of calculating the target modulation parameters that satisfy the soft-switching conditions for the AC-DC converter to operate in the current operating mode can be:

[0087] According to the first phase shift angle, the second duty cycle, and the preset correlation relationship between the phase shift angle and the duty cycle, calculate the fourth duty cycle of each switch tube in the AC side H-bridge; use the first phase shift angle, the third duty cycle, and the fourth duty cycle as the first modulation parameters.

[0088] It should be noted that for an AC-DC converter with the same topology structure and in the same operating mode, there is a fixed correlation relationship between the phase shift angle and the duty cycle, that is, there is a fixed correlation relationship between the phase shift angle and the duty cycle of each switch tube in the AC side H-bridge and the duty cycle of the output voltage at the midpoint of the DC side H-bridge arm.

[0089] For a single-stage bidirectional isolated AC-DC converter, its key waveforms are as Figure 4 shown, and the fixed correlation relationship between the phase shift angle and the duty cycle of each switch tube in the AC side H-bridge and the duty cycle of the output voltage at the midpoint of the DC side H-bridge arm can be expressed as:

[0090] Since in the process of determining whether the current operating mode of the AC-DC converter is the first mode, the first phase shift angle that satisfies the soft-switching conditions for the AC-DC converter to operate in the first mode and can make the input current of the AC-DC converter match the AC current reference value, and the third duty cycle of the output voltage at the midpoint of the DC side H-bridge arm have been calculated; therefore, the fourth duty cycle of each switch tube in the AC side H-bridge can be directly calculated according to the first phase shift angle, the second duty cycle, and the preset correlation relationship between the phase shift angle and the duty cycle; that is, the first modulation parameters that satisfy the soft-switching conditions for the AC-DC converter to operate in the first mode and can make the input current of the AC-DC converter match the AC current reference value are obtained.

[0091] Further, when the current working mode is the first mode, the implementation manner of generating the switching tube driving signal based on the target modulation parameter and the switching tube driving timing corresponding to the current working mode may be as follows:

[0092] Generate the switching tube driving signals according to the first modulation parameter and the switching tube driving timings corresponding to the first mode respectively; for example, for the part where Vac>0, according to the first modulation parameter, generate driving signals for switching tubes Q1, Q3, Q1', and Q3' according to the first driving timing (refer to Figure 4 ), and switching tubes Q2, Q4, Q2', and Q4' maintain a high level; for the part where Vac<0, switching tubes Q1, Q3, Q1', and Q3' maintain a high level, and switching tubes Q2, Q4, Q2', and Q4' generate driving signals according to the second driving timing (refer to Figure 4 ).

[0093] It can be understood that the first duty cycles of the switching tubes in the AC side H-bridge calculated above include the duty cycles of Q1', Q3' (Q2', Q4'), and the duty cycles of Q2, Q4 (Q1, Q3) that maintain a high level correspondingly.

[0094] In this embodiment, according to the AC voltage, DC voltage, AC current reference value, and the soft-switching conditions of the AC-DC converter operating in the preset working mode, analyze the current working mode of the AC-DC converter, and analyze that when the current working mode is the first mode, by obtaining the first modulation parameter that satisfies the soft-switching conditions of the AC-DC converter operating in the first mode and can make the input current of the AC-DC converter match the AC current reference value, the target current control is realized while reducing the switching tube loss, and the efficiency of the converter is improved as a whole.

[0095] Based on the first embodiment and the second embodiment of the present application, in the third embodiment of the present application, the same or similar content as that in the above-mentioned first embodiment can be referred to the above introduction and will not be repeated hereinafter. Refer to Figure 3 , on this basis, when the current working mode is the second mode, the target modulation parameter includes the second modulation parameter, and the implementation manner of calculating the target modulation parameter that satisfies the soft-switching conditions of the AC-DC converter operating in the current working mode may be as follows:

[0096] Calculate the phase-shifting angle range of the AC-DC converter operating in the second mode according to the AC voltage, DC voltage, AC current reference value, and the maximum and minimum duty cycles of the output voltage at the midpoint of the DC side H-bridge arm; calculate the second modulation parameter that satisfies the soft-switching conditions of the AC-DC converter operating in the second mode according to the AC voltage, DC voltage, AC current reference value, and the phase-shifting angle range.

[0097] It should be noted that, when the current working mode is the second mode, in order to avoid the current modulation parameters being able to reach the soft switching condition, the AC-DC converter cannot output a sufficiently large current, resulting in a reduction in gain (current conversion capability), thereby reducing the working efficiency of the AC-DC converter; and also to avoid short circuits caused by excessive duty cycles; this embodiment calculates the phase shift angle range of the AC-DC converter working in the second mode based on the AC voltage, DC voltage, AC current reference value, and the maximum duty cycle and minimum duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side. Further, based on the AC voltage, DC voltage, AC current reference value and phase shift angle range, the second modulation parameter that satisfies the soft switching condition of the AC-DC converter working in the second mode is calculated, so as to improve the working efficiency of the AC-DC converter while ensuring the normal operation of the AC-DC converter.

[0098] Specifically, the minimum phase shift angle φmin of the AC-DC converter operating in the second mode can be calculated based on the AC voltage, DC voltage, AC current reference value, and the maximum duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side, wherein, for a single-stage bidirectional isolated AC-DC converter, the maximum duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side is 0.5.

[0099] For example, according to the working principle of the AC-DC converter, the average value of the AC current in a single PWM cycle theoretically when the AC-DC converter works in the second mode is i avr2 With the AC current reference value i ac_ref Matching, we get equation 3, and the combined equations of equation 4 (d2=0.5) calculate the minimum phase shift angle φmin.

[0100] Where, Equation 3 is:

[0101] i ac_ref *L=K*V dc *T*(-16*φ 2 +8*φ-4*d2 2 +4*d2-1);

[0102] The AC-DC converter works in the second mode.

[0103] Furthermore, based on the AC voltage, DC voltage, AC current reference value, and the minimum duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side, the maximum phase shift angle φmax of the AC-DC converter operating in the second mode is calculated, wherein, for a single-stage bidirectional isolated AC-DC converter, the minimum duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side can be expressed as: d2=0.5-2*φ.

[0104] For example, the maximum phase shift angle φmax is calculated based on the system of equations formed by equation 3 and the expression (d2=0.5-2*φ).

[0105] It can be understood that the phase shift angle range is [φmin, φmax].

[0106] Further, the second modulation parameters include a second phase shift angle, a fifth duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side, and a sixth duty cycle of each switch tube in the H-bridge on the AC side; according to the AC voltage, the DC voltage, the AC current reference value and the phase shift angle range, the implementation method of calculating the second modulation parameters that meet the soft switching condition of the AC-DC converter operating in the second mode may be:

[0107] The second phase shift angle is calculated according to the AC voltage, the DC voltage, the soft switching condition of the AC-DC converter working in the second mode and the maximum duty cycle of each switch tube in the AC side H bridge; the second phase shift angle is limited according to the phase shift angle range to obtain the phase shift angle after limiting; the fifth duty cycle is calculated according to the phase shift angle after limiting and the AC current reference value; the sixth duty cycle is calculated according to the second phase shift angle, the fifth duty cycle, and the preset relationship between the phase shift angle and the duty cycle.

[0108] Specifically, it can be based on the soft switching condition of the AC-DC converter working in the first mode, and the current i at the time of the switch tube being turned off when the AC-DC converter works in the second mode. t4 , we get equation 4: The second phase shift angle is calculated according to equation 4 and the maximum duty cycle (d=0.5) of each switch tube in the AC side H bridge.

[0109] Among them, the current i when the switch tube is turned off when the AC-DC converter works in the second mode is t4 The expression is:

[0110]

[0111] Among them, for the single-stage bidirectional isolated AC-DC converter, the maximum duty cycle of each switch tube in the AC side H bridge is 0.5.

[0112] Further, according to the phase shift angle range, the second phase shift angle is limited to obtain the phase shift angle after limiting, and the fifth duty cycle is calculated according to the phase shift angle after limiting and the AC current reference value; that is, the phase shift angle after limiting is substituted into i t4 The fifth duty cycle can be calculated from the expression.

[0113] For a single-stage bidirectional isolated AC-DC converter, its key waveforms are as follows: Figure 4As shown, there is a fixed correlation between the phase shift angle, the duty cycles of the switching transistors in the AC-side H-bridge, and the duty cycle of the output voltage at the midpoint of the DC-side H-bridge arm, which can be expressed as: After calculating the second phase shift angle and the fifth duty cycle, the sixth duty cycle can be calculated according to the second phase shift angle, the fifth duty cycle, and the preset correlation between the phase shift angle and the duty cycle; that is, the second modulation parameters that satisfy the soft-switching condition when the AC-DC converter operates in the second mode and can make the input current of the AC-DC converter match the AC current reference value are obtained.

[0114] Furthermore, when the current operating mode is the second mode, the implementation manner of generating the switching transistor drive signal based on the target modulation parameters and the switching transistor drive timing corresponding to the current operating mode can be:

[0115] Generate the switching transistor drive signals according to the second modulation parameters and the switching transistor drive timing corresponding to the second mode; for example, for the part where Vac > 0, according to the second modulation parameters, generate drive signals for the switching transistors Q1, Q3, Q1', Q3' according to the second drive timing (refer to Figure 5 ), and the switching transistors Q2, Q4, Q2', Q4' remain at high level; for the part where Vac < 0, the switching transistors Q1, Q3, Q1', Q3' remain at high level, and the switching transistors Q2, Q4, Q2', Q4' generate drive signals according to the second drive timing (refer to Figure 5 ).

[0116] In this embodiment, calculating the range of the phase shift angle when the AC-DC converter operates in the second mode according to the AC voltage, the DC voltage, the AC current reference value, and the maximum and minimum duty cycles of the output voltage at the midpoint of the DC-side H-bridge arm can ensure the normal operation of the AC-DC converter; calculating the second modulation parameters that satisfy the soft-switching condition when the AC-DC converter operates in the second mode and can make the input current of the AC-DC converter match the AC current reference value realizes improving the operating efficiency of the AC-DC converter while ensuring the normal operation of the AC-DC converter.

[0117] It should be noted that when the AC-DC converter is used as an inverter, the above converter control method is the same. The difference is that the phase shift angle calculated when the AC-DC converter is used as an inverter and the phase shift angle calculated when the AC-DC converter is used as a rectifier have opposite signs.

[0118] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the converter control method of this application. Based on this technical concept, more forms of simple transformations are within the protection scope of this application.

[0119] The present application provides a controller, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the converter control method in the first embodiment above.

[0120] Reference is made below to Figure 6 , which shows a schematic structural diagram of a controller suitable for implementing the embodiments of the present application. Figure 6 The controller shown is merely an example and should not impose any limitation on the functions and scope of use of the embodiments of the present application. As Figure 6 shown, the controller may include a processing device 1001 (such as a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM: Read Only Memory) 1002 or a program loaded from a storage device 1003 into a random access memory (RAM: Random Access Memory) 1004. In the RAM 1004, various programs and data required for the operation of the controller are also stored. The processing device 1001, the ROM 1002, and the RAM 1004 are connected to each other through a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Generally, the following systems may be connected to the I / O interface 1006: an input device 1007 including, for example, a touch screen, a touch pad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; an output device 1008 including, for example, a liquid crystal display (LCD: Liquid Crystal Display), a speaker, a vibrator, etc.; a storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 may allow the controller to communicate with other devices wirelessly or wiredly to exchange data. Although the figure shows a controller having various systems, it should be understood that it is not required to implement or include all the systems shown. More or fewer systems may be implemented or included alternatively.

[0121] Specifically, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes program codes for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication device, or installed from the storage device 1003, or installed from the ROM 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the method of the embodiments disclosed in the present application are executed.

[0122] The controller provided by the present application adopts the converter control method in the above embodiment, and can solve the technical problem of low working efficiency of the single-stage bidirectional isolated AC-DC converter. Compared with the prior art, the beneficial effects of the controller provided by the present application are the same as those of the converter control method provided by the above embodiment, and other technical features in this controller are the same as those disclosed in the method of the previous embodiment, which will not be elaborated here.

[0123] It should be understood that the various parts disclosed in the present application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0124] As described above, only the specific embodiments of the present application are provided, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present application, and all should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0125] The present application provides a computer-readable storage medium having computer-readable program instructions (i.e., computer programs) stored thereon, and the computer-readable program instructions are used to execute the converter control method in the above embodiment.

[0126] The computer-readable storage medium provided by the present application can be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or components, or any combination of the above. More specific examples of computer-readable storage media can include: electrical connections with one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM) or flash memory, optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the above. In this embodiment, the computer-readable storage medium can be any tangible medium that contains or stores a program, and the program can be used by or in combination with an instruction execution system, device or component. The program code contained on the computer-readable storage medium can be transmitted by any appropriate medium, including: wires, optical cables, RF (radio frequency), etc., or any suitable combination of the above.

[0127] The above computer-readable storage medium may be included in the controller; or may exist separately without being assembled into the controller.

[0128] The above computer-readable storage medium carries one or more programs, which, when executed by the controller, cause the controller to: execute the above transducer control method.

[0129] Computer program code for performing the operations of the present application may be written in one or more programming languages or combinations thereof. The programming languages include object-oriented programming languages such as Java, Smalltalk, C++, and also include conventional procedural programming languages such as the "C" language or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, executed as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., through the Internet using an Internet service provider).

[0130] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of the systems, methods, and computer program products according to the embodiments of the present application. In this regard, each block in the flowchart or block diagram may represent a module, a program segment, or a part of code that contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than marked in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and combinations of blocks in the block diagram and / or flowchart, may be implemented by a dedicated hardware-based system for performing the specified functions or operations, or may be implemented by a combination of dedicated hardware and computer instructions.

[0131] The modules described in the embodiments of the present application may be implemented in software or in hardware. In some cases, the name of the module does not constitute a limitation on the unit itself.

[0132] The readable storage medium provided by this application is a computer-readable storage medium, and the computer-readable storage medium stores computer-readable program instructions (i.e., computer programs) for executing the above-mentioned converter control method, which can solve the technical problem of low working efficiency of the single-stage bidirectional isolated AC-DC converter. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided by this application are the same as those of the converter control method provided by the above embodiments, and will not be elaborated here.

[0133] This application also provides a computer program product, including a computer program, and when the computer program is executed by a processor, it realizes the steps of the converter control method as described above.

[0134] The computer program product provided by this application can solve the technical problem of low working efficiency of the single-stage bidirectional isolated AC-DC converter. Compared with the prior art, the beneficial effects of the computer program product provided by this application are the same as those of the converter control method provided by the above embodiments, and will not be elaborated here.

[0135] The above are only partial embodiments of this application, and thus do not limit the patent scope of this application. Any equivalent structural transformation made under the technical concept of this application by using the content of the specification and drawings of this application, or any direct / indirect application in other related technical fields, is included in the patent protection scope of this application.

Claims

1. A converter control method, characterized in that: The method includes: Determining a current operating mode of the AC-DC converter according to the acquired AC voltage and DC voltage of the AC-DC converter; Calculating target modulation parameters that satisfy the soft switching condition of the AC-DC converter operating in the current working mode, wherein the target modulation parameters include a target phase shift angle, a first duty cycle of each switch tube in the AC side H bridge, and a second duty cycle of the output voltage at the midpoint of the bridge arm of the DC side H bridge, and the phase shift angle is the phase difference between the output voltages at the midpoints of the bridge arms corresponding to the AC side H bridge and the DC side H bridge respectively; Based on the target modulation parameter, a switch tube driving signal is generated to achieve control of the converter.

2. The method according to claim 1, characterized in that The step of determining the current working mode of the AC-DC converter according to the acquired AC voltage and DC voltage of the AC-DC converter comprises: The current working mode of the AC-DC converter is determined according to the AC voltage, the DC voltage, the AC current reference value and the soft switching condition of the AC-DC converter working in a preset working mode.

3. The method according to claim 2, characterized in that The working mode of the AC-DC converter is divided into a first mode and a second mode; when the preset working mode is the first mode, the step of determining the current working mode of the AC-DC converter according to the AC voltage, the DC voltage, the AC current reference value and the soft switching condition of the AC-DC converter working in the preset working mode includes: Calculate, according to the AC voltage, DC voltage, and AC current reference values, a first phase shift angle that satisfies the soft switching condition of the AC-DC converter operating in the first mode and a third duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side; According to the first phase shift angle, the third duty cycle and the preset mode division condition, judging whether the current working mode of the AC-DC converter is the first mode, wherein the preset mode division condition is determined according to the magnitude relationship between the phase shift angle and the duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side; When the current operating mode is not the first mode, the current operating mode of the AC-DC converter is determined to be the second mode.

4. The method according to claim 3, characterized in that In the case where the current working mode is the first mode, the step of calculating the target modulation parameter that satisfies the soft switching condition of the AC-DC converter working in the current working mode includes: Calculating a fourth duty cycle of each switch tube in the AC side H bridge according to the first phase shift angle, the second duty cycle, and a preset correlation between the phase shift angle and the duty cycle; The first phase shift angle, the third duty cycle and the fourth duty cycle are used as the first modulation parameters.

5. The method according to claim 2, characterized in that In the case where the current working mode is the second mode, the target modulation parameter includes the second modulation parameter, and the step of calculating the target modulation parameter that satisfies the soft switching condition of the AC-DC converter working in the current working mode includes: Calculate the phase shift angle range of the AC-DC converter operating in the second mode according to the AC voltage, DC voltage, AC current reference value, and the maximum duty cycle and minimum duty cycle of the DC side H-bridge arm midpoint output voltage; A second modulation parameter satisfying a soft switching condition for the AC-DC converter operating in a second mode is calculated according to the AC voltage, the DC voltage, the AC current reference value and the phase shift angle range.

6. The method according to claim 5, characterized in that The second modulation parameters include a second phase shift angle, a fifth duty cycle of the output voltage at the midpoint of the H-bridge arm on the DC side, and a sixth duty cycle of each switch tube in the H-bridge on the AC side; the step of calculating the second modulation parameters that meet the soft switching condition of the AC-DC converter operating in the second mode according to the AC voltage, the DC voltage, the AC current reference value and the phase shift angle range includes: Calculating a second phase shift angle according to the AC voltage, the DC voltage, the soft switching condition of the AC-DC converter operating in the second mode, and the maximum duty cycle of each switch tube in the AC side H bridge; According to the phase shift angle range, limiting the second phase shift angle to obtain a phase shift angle after limiting; Calculating the fifth duty cycle according to the phase shift angle after limiting and the AC current reference value; The sixth duty cycle is calculated according to the second phase shift angle, the fifth duty cycle, and a preset correlation relationship between the phase shift angle and the duty cycle.

7. The method according to any one of claims 1 to 6, characterized in that: The step of generating a switch tube drive signal based on the target modulation parameter includes: A switch tube driving signal is generated based on the target modulation parameter and the switch tube driving timing corresponding to the current working mode.

8. The method according to any one of claims 1 to 6, characterized in that The AC-DC converter is a single-stage bidirectional isolated AC-DC converter.

9. A controller, characterized in that: The controller comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the converter control method according to any one of claims 1 to 8.

10. A storage medium, characterized in that: The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the converter control method according to any one of claims 1 to 8 are implemented.

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