Control method of power conversion circuit, power conversion device and energy storage equipment

Abstract

The invention provides a control method of a power conversion circuit, a power conversion device and energy storage equipment. The control method comprises the following steps: acquiring a working condition parameter of the power conversion circuit, a preset current range of a secondary peak current, a phase shift ratio of the secondary peak current and the power conversion circuit and a constraint relationship between the phase shift ratio and an internal phase shift angle, and then obtaining a target phase shift ratio and a target internal phase shift angle according to the preset current range, the working condition parameter and the constraint relationship; calculating a target switching frequency according to the working condition parameters, the target phase shift ratio, the target internal phase shift angle and the constraint relation, and finally generating a control signal according to the target switching frequency, the target phase shift ratio and the target internal phase shift angle to control the output of the power conversion circuit so as to enable the secondary side peak current to be within a preset current range. According to the method, the output of the power conversion circuit can be controlled, the current stress of the power conversion circuit can be reduced, and normal operation of the power conversion circuit is facilitated.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a control method for a power conversion circuit, a power conversion device, and an energy storage device. Background Art

[0002] Single-stage power conversion circuits such as dual active bridges (DAB) converters are currently mainly used in micro inverters, with advantages such as low cost and high transmission efficiency. During use, if the current passes through the conductor and generates excessive current stress, it will cause damage to circuit components and is not conducive to the normal operation of the power conversion circuit. Summary of the invention

[0003] In view of this, the present application provides a control method for a power conversion circuit, a power conversion device and an energy storage device, which can reduce the current stress of the power conversion circuit and facilitate the normal operation of the power conversion circuit.

[0004] The first aspect of the present application provides a control method for a power conversion circuit, wherein the power conversion circuit includes a DC side bridge circuit, an AC side bridge circuit and a transformer, the DC side bridge circuit is connected to the primary side of the transformer, and the AC side bridge circuit is connected to the secondary side of the transformer. The control method includes: obtaining the operating parameters of the power conversion circuit; obtaining the preset current range of the secondary side peak current, the constraint relationship between the secondary side peak current and the phase shift ratio and internal phase shift angle of the power conversion circuit; obtaining the target phase shift ratio and the target internal phase shift angle according to the preset current range, the operating parameters and the constraint relationship; calculating the target switching frequency according to the operating parameters, the target phase shift ratio, the target internal phase shift angle and the constraint relationship; generating a control signal according to the target switching frequency, the target phase shift ratio and the target internal phase shift angle, and the control signal is used to control the output of the power conversion circuit so that the secondary side peak current is within the preset current range.

[0005] In the control method of the power conversion circuit of the present application, by obtaining the operating parameters of the power conversion circuit, the secondary side peak current and the phase shift ratio and the internal phase shift angle of the power conversion circuit, the target phase shift ratio and the target internal phase shift angle are obtained according to the operating parameters and the constraint relationship, and then the target switching frequency is calculated according to the operating parameters, the target phase shift ratio, the target internal phase shift angle and the constraint relationship, and finally the control signal can be generated according to the target switching frequency, the target phase shift ratio and the target internal phase shift angle to control the output of the power conversion circuit. Since the target phase shift ratio and the target internal phase shift angle obtained according to the operating parameters and the constraint relationship can constrain the secondary side peak current within the preset current range, the current stress of the circuit can be reduced while satisfying the normal operation of the power conversion circuit. Therefore, through the method of the present application, the output of the power conversion circuit can be controlled to reduce the current stress of the power conversion circuit, reduce the risk of damage to circuit components and circuit function failure, and is conducive to the normal operation of the power conversion circuit.

[0006] In one embodiment, the operating parameters include at least: the actual input voltage of the DC side bridge circuit, the actual output voltage and actual output current of the AC side bridge circuit, the turns ratio of the transformer and the preset phase shift ratio range. According to the preset current range, the operating parameters and the constraint relationship, the process of obtaining the target phase shift ratio and the target internal phase shift angle includes: determining the first phase shift ratio within the preset phase shift ratio range according to the preset current range, the actual input voltage, the actual output voltage, the turns ratio, the preset phase shift ratio range and the constraint relationship; determining the target internal phase shift angle according to the actual input voltage, the actual output voltage, the turns ratio, the first phase shift ratio and the constraint relationship; obtaining the zero voltage switch constraint condition of the power conversion circuit; determining the second phase shift ratio according to the target internal phase shift angle, the operating parameters and the zero voltage switch constraint condition; determining the target phase shift ratio according to the first phase shift ratio and the second phase shift ratio.

[0007] In one embodiment, the zero voltage switching constraint is related to an actual input voltage, an actual output voltage, a turns ratio, and a target internal phase shift angle.

[0008] In one embodiment, determining the target shift ratio according to the first shift ratio and the second shift ratio includes: determining the target shift ratio according to a larger value of the first shift ratio and the second shift ratio.

[0009] In one embodiment, the target switching frequency is calculated based on operating parameters, target phase shift ratio, target internal phase shift angle and constraint relationship, including: determining the reference switching frequency based on the operating parameters, target internal phase shift angle, target phase shift ratio and constraint relationship; determining the switching frequency compensation value based on the operating parameters, target internal phase shift angle, target phase shift ratio and reference output voltage of the power conversion circuit; determining the target switching frequency based on the switching frequency compensation value and the reference switching frequency.

[0010] In one embodiment, a switching frequency compensation value is determined based on operating parameters, a target internal phase shift angle, a target phase shift ratio, and a reference output voltage of a power conversion circuit, including: performing deviation processing on a voltage difference between a reference output voltage and an actual output voltage of an AC side bridge circuit to obtain an initial current value; obtaining a current regulation value based on the initial current value and an actual output current of an AC side bridge circuit; determining a compensation factor based on operating parameters, a target internal phase shift angle, a target phase shift ratio, and a constraint relationship; the compensation factor is positively correlated with the product of a reference peak current and a switching frequency; and performing deviation processing on a ratio between the current regulation value and the compensation factor to obtain a switching frequency compensation value.

[0011] In one embodiment, determining the target switching frequency according to the switching frequency compensation value and the reference switching frequency includes: calculating the total value between the switching frequency compensation value and the inverse of the reference switching frequency; and obtaining the target switching frequency after taking the inverse of the total value.

[0012] In one embodiment, both the DC side bridge circuit and the AC side bridge circuit include switching tubes; a control signal is generated according to a target switching frequency, a target phase shift ratio, and a target internal phase shift angle, including: a pulse frequency modulation control signal is generated according to the target switching frequency, the target phase shift ratio, and the target internal phase shift angle, and the pulse frequency modulation control signal is used to control the on and off state of the switching tube in the power conversion circuit.

[0013] A second aspect of the present application provides a power conversion device, which includes a power conversion circuit and a controller, and the controller is used to execute the control method of the power conversion circuit described in the first aspect or any one of the embodiments of the first aspect.

[0014] The third aspect of the present application provides an energy storage device, which includes an energy storage battery and the power conversion device described in the second aspect above, the energy storage battery is connected to the power conversion device and provides direct current to the power conversion device.

[0015] The fourth aspect of the present application provides a power device, which includes a motor and the power conversion device described in the second aspect above, the motor is connected to the power conversion device and is powered by the power conversion device.

[0016] The fifth aspect of the present application provides an electronic device, including a processor and a memory, the memory is used to store programs, instructions or codes, and the processor is used to execute the programs, instructions or codes in the memory to complete the control method of the power conversion circuit described in the first aspect or any one of the embodiments of the first aspect.

[0017] In a sixth aspect of the present application, there is provided a control device for a power conversion circuit, comprising a first acquisition module, a second acquisition module, a first calculation module, a second calculation module and a generation module; the first acquisition module is used to acquire the operating parameters of the power conversion circuit; the second acquisition module is used to acquire the preset current range of the secondary side peak current, the constraint relationship between the secondary side peak current and the phase shift ratio and the internal phase shift angle of the power conversion circuit; the first calculation module is used to obtain the target phase shift ratio and the target internal phase shift angle according to the preset current range, the operating parameters and the constraint relationship; the second calculation module is used to calculate the target switching frequency according to the operating parameters, the target phase shift ratio, the target internal phase shift angle and the constraint relationship; the generation module is used to generate a control signal according to the target switching frequency, the target phase shift ratio and the target internal phase shift angle, and the control signal is used to control the output of the power conversion circuit so that the secondary side peak current is within the preset current range.

[0018] A seventh aspect of the present application provides a computer-readable storage medium storing a computer program, which is loaded by a processor to execute the control method of the power conversion circuit described in the first aspect or any one of the embodiments of the first aspect.

[0019] In addition, the technical effects brought about by any possible implementation method in the second to seventh aspects can refer to the technical effects brought about by different implementation methods in the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A This is an application scenario diagram of the control method of the power conversion circuit provided in an embodiment of the present application.

[0021] Figure 1B This is another application scenario diagram of the power conversion circuit control method provided in an embodiment of the present application.

[0022] Figure 2 It is a circuit schematic diagram of the power conversion circuit in Figure 1.

[0023] Figure 3A is Figure 2 The timing diagram of the control signal when the power conversion circuit is in the inverter state.

[0024] Figure 3B is Figure 2 The timing diagram of the control signal when the power conversion circuit is in the rectification state.

[0025] Figure 4 yes Figure 2 The schematic diagram of the primary voltage, secondary voltage and secondary peak current when the power conversion circuit is inverted is shown.

[0026] Figure 5It is a flow chart of a control method of a power conversion circuit provided in an embodiment of the present application.

[0027] Figure 6 yes Figure 5 A detailed flowchart of step S20 in FIG.

[0028] Figure 7 yes Figure 5 A detailed flowchart of step S30 in FIG.

[0029] Figure 8 yes Figure 7 A detailed flowchart of step S32 in FIG.

[0030] Fig. 9 yes Figure 7 A detailed flowchart of step S33 in FIG.

[0031] Fig.10 The power conversion circuit is not used Figure 5 A simulation waveform diagram under the method shown.

[0032] Fig.11 The power conversion circuit uses Figure 5 A simulation waveform diagram under the method shown.

[0033] Fig.12 It is a control block diagram of a control method for a power conversion circuit provided in an embodiment of the present application.

[0034] Fig.13 It is a schematic diagram of a power conversion device provided in an embodiment of the present application.

[0035] Fig.14 It is a schematic diagram of an energy storage device provided in an embodiment of the present application.

[0036] Fig.15 It is a schematic diagram of the power equipment provided in an embodiment of the present application.

[0037] Fig.16 It is a schematic diagram of an electronic device provided in an embodiment of the present application.

[0038] Fig.17 It is a schematic diagram of a control device for a power conversion circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] It should be noted that the terms "first" and "second" in the specification, claims and drawings of the present application are used to distinguish similar objects rather than to describe a specific order or sequence.

[0040] It should also be noted that the method disclosed in the embodiments of the present application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchangeable with each other, and some of the steps can also be deleted.

[0041] Some embodiments will be described below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0042] Single-stage power conversion circuits such as dual active bridges (DAB) converters are currently mainly used in micro inverters, with advantages such as low cost and high transmission efficiency. During use, if the current passes through the conductor and generates excessive current stress, it will cause damage to circuit components and is not conducive to the normal operation of the power conversion circuit.

[0043] Therefore, an embodiment of the present application provides a control method for a power conversion circuit, which can effectively control the power conversion circuit to reduce the current stress of the power conversion circuit, thereby facilitating the normal operation of the power conversion circuit.

[0044] The technical solution of the present application is further described in detail below in conjunction with the accompanying drawings.

[0045] See also Figure 1A , which is an application scenario diagram of the control method of the power conversion circuit in an embodiment of the present application. Figure 1A The scenario includes a power conversion circuit 10 , a DC power supply 20 and an AC load 30 .

[0046] Specifically, the power conversion circuit 10 includes a DC side bridge circuit 11, a transformer 12, and an AC side bridge circuit 13. A first end of the DC side bridge circuit 11 is connected to the primary side of the transformer 12, a second end of the DC side bridge circuit 11 is used to connect to a DC power source 20, a secondary side of the transformer 12 is connected to a first end of the AC side bridge circuit 13, and a second end of the AC side bridge circuit 13 is used to connect to an AC load 30.

[0047] Wherein, the DC side bridge circuit 11 can adopt a full-bridge topology or a half-bridge topology, and the AC side bridge circuit 13 can also adopt a full-bridge topology or a half-bridge topology, which is not limited here. The turns ratio of the transformer 12 can be n. n can be determined according to the transformation ratio between the output end and the input end of the transformer. In this embodiment, the transformer 12 is a step-up transformer, so n is a positive number greater than 1.

[0048] The DC power source 20 may be a photovoltaic power generation device, a rechargeable energy storage battery or other power source that can provide DC power. The AC load 30 may be any electronic load that needs to consume AC power, such as a motor or various AC loads in a household, or a linear load or a nonlinear load. The linear load may be a resistive load, an inductive load, a capacitive load, etc. The nonlinear load may be various converters, or an RCD load including a capacitor, a resistor and a diode.

[0049] Based on such a design, the DC side bridge circuit 11 can be used to invert the energy of the DC power supply 20 and transmit it to the transformer 12, and the transformer 12 then transmits the energy to the AC side bridge circuit 13 through the magnetic field, and the AC side bridge circuit 13 can be used to convert the energy and transmit it to the AC load 30. It can be seen that the power conversion circuit 10 is in an inversion state at this time, and can invert the DC power of the DC power supply 20 into AC power and output it to the AC load 30, and the energy flow direction is from the DC side bridge circuit 11 to the AC side bridge circuit 13.

[0050] In another scenario, the power conversion circuit 10 can also be compatible with realizing energy flow from the AC side bridge circuit 13 to the DC side bridge circuit 11. For example, please refer to Figure 1B ,and Figure 1A Compared with the scene, Figure 1B The scenario also includes a DC load 40 and an AC power source 50 .

[0051] Specifically, the second end of the DC side bridge circuit 11 can be used not only to connect the DC power supply 20, but also to connect the DC load 40. The second end of the AC side bridge circuit 13 can be used not only to connect the AC load 30, but also to connect the AC power supply 50. The AC power supply 50 can be a power grid or an AC power supply such as an oil machine or a charging pile. Among them, the power grid can be a municipal power grid, other local power grids or a microgrid. In this embodiment, the AC power supply 50 is taken as an example of a power grid. The DC load 40 can be any electronic load that needs to consume DC power.

[0052] Based on such a design, as mentioned above, the power conversion circuit 10 can be used to invert the DC power of the DC power source 20 into AC power to supply power to the AC load 30. In addition, after obtaining the grid feeding permission, the excess energy after inversion can be fed into the grid.

[0053] Conversely, the power conversion circuit 10 can also be used to rectify the AC power of the power grid into DC power and then supply power to the DC load 40 or charge the DC power source 20. At this time, the power conversion circuit 10 is in a rectifying state, and the energy flows from the AC side bridge circuit 13 to the DC side bridge circuit 11. It can be seen that the power conversion circuit 10 can realize bidirectional energy flow.

[0054] Among them, the direction in which energy flows from the DC side bridge circuit 11 to the AC side bridge circuit 13 can be defined as the forward direction, and the direction in which energy flows from the AC side bridge circuit 13 to the DC side bridge circuit 11 can be defined as the reverse direction. Of course, in other embodiments, the forward and reverse directions can also be reversed, depending on the actual situation, and are all within the scope of the embodiments of the present application.

[0055] In addition, if the AC side bridge circuit 13 is connected to the grid, the power conversion circuit 10 is in a grid-connected operation state. If the AC side bridge circuit 13 is not connected to the grid or the grid loses power, causing the AC side bridge circuit 13 to be disconnected from the grid, the power conversion circuit 10 is in an off-grid operation state.

[0056] In the embodiments of the present application, Figure 1A and Figure 1B The illustrated scenario also includes a controller 60, which may be a microcontroller unit (MCU) or other control circuit. The controller 60 is connected to the DC side bridge circuit 11 and the AC side bridge circuit 13, so that it can be used to control the DC side bridge circuit 11 to realize the DC-AC (i.e. Direct Current-Alternating Current, DC-AC) conversion function, and control the AC side bridge circuit 13 to realize the AC-AC (i.e. Alternating Current-Alternating Current, AC-AC) conversion function. In another embodiment, the DC side bridge circuit 11 and the AC side bridge circuit 13 can also be controlled separately by dual controllers.

[0057] In the embodiment of the present application, the controller 60 can use an extended phase shift (EPS) control method to control the conversion process of the power conversion circuit 10. The EPS control method uses two phase shift degrees of freedom, which can include an inner phase shift angle φ and an outer phase shift angle Or the inner phase angle φ and the ratio K, where K is the outer phase angle The power conversion circuit 10 can be flexibly controlled by controlling the two phase shift degrees of freedom.

[0058] Furthermore, the controller 60 may be used to execute the power conversion circuit control method provided in the embodiment of the present application to control the output of the power conversion circuit 10 , thereby preventing the current stress of the power conversion circuit 10 from being too large and affecting the normal operation of the circuit 10 .

[0059] For a better understanding, the following Figure 2 The power conversion circuit 10 is further described by taking the circuit shown as an example. Figure 2In the power conversion circuit 10 shown, the DC side bridge circuit 11 adopts a full-bridge topology, and the AC side bridge circuit 13 adopts a half-bridge topology.

[0060] Specifically, Figure 2 As shown, the DC side bridge circuit 11 includes switch tubes S1 to S4, the switch tubes S1 and S2 are connected in series to form one bridge arm, the switch tubes S3 and S4 are connected in series to form another bridge arm, and the two bridge arms are connected in parallel. Figure 2 Points a, b) in the figure constitute the first end of the DC side bridge circuit 11. The two ends of the two bridge arms constitute the second end of the DC side bridge circuit 11. A first capacitor unit may also be connected in parallel between the DC side bridge circuit 11 and the DC power supply 20. The first capacitor unit may include a capacitor C1 and a resistor R1 connected in series. Of course, in other embodiments, the first capacitor unit may also directly use the capacitor C1, or other circuits including the capacitor C1.

[0061] The AC side bridge circuit 13 includes switch tubes S5~S8, a second capacitor unit and a third capacitor unit. The switch tubes S5~S8 constitute the first bridge arm, and the second capacitor unit and the third capacitor unit constitute the second bridge arm. Specifically, the switch tubes S5 and S6 are connected in series and oppositely arranged (that is, reverse series connection) to form the upper bridge arm of the first bridge arm. The switch tubes S7 and S8 are connected in series and oppositely arranged to form the lower bridge arm of the first bridge arm, and the upper bridge arm and the lower bridge arm are connected in series to form the first bridge arm. The second capacitor unit constitutes the upper bridge arm of the second bridge arm, and the third capacitor unit constitutes the lower bridge arm of the second bridge arm. The second capacitor unit and the third capacitor unit are connected in series to form the second bridge arm. The midpoint of the two bridge arms (corresponding to Figure 2 Points c and d in the figure constitute the first end of the AC side bridge circuit 13. The two ends of the two bridge arms constitute the second end of the AC side bridge circuit 13. The structures of the second capacitor unit and the third capacitor unit can be the same or similar to those of the first capacitor unit. Figure 2 The second capacitor unit includes a capacitor C2 and a resistor R2 connected in series, and the third capacitor unit includes a capacitor C3 and a resistor R3 connected in series.

[0062] Based on this design, Figure 2 The circuit 10 shown may also be referred to as a dual active bridge converter.

[0063] The switch tubes S1-S4, S5-S8 can adopt corresponding types of semiconductor switches according to actual conditions, such as triodes, MOSFETs or IGBTs, etc., and this application does not make specific restrictions on this. The switch tubes S1-S4, S5-S8 can be used to receive control signals from the controller 60, and then turn on or off under the control of the control signal. The duty cycle of the control signal and the switching frequency f s The on-off status of the switches S1 - S8 is determined, thereby affecting the energy transmission of the power converter 10 .

[0064] The power conversion circuit 10 may further include a secondary leakage inductance L k , secondary leakage inductance L k It can be set independently or integrated into the transformer 12 (see Figure 2 For ease of understanding, Figure 2 The circuit shows the secondary leakage inductance L k , secondary leakage inductance L k Connected between the secondary side of the transformer 12 and the bridge arm midpoint c. g It can be a filter inductor, one end of which is connected to the capacitor C2 , and the other end of which is connected to the first end of the AC side bridge circuit 13 .

[0065] Please also read Figure 3A and Figure 3B , Figure 3A 1 shows a timing diagram of control signals when the power conversion circuit 10 is in an inverter state, Figure 3B The timing diagram of the control signal when the power conversion circuit 10 is in the rectification state is shown. In a complete switching cycle Ts, the operation of the DC side bridge circuit 11 in the positive and negative half cycles is symmetrical, and the AC side bridge circuit 13 is also the same. Therefore, Figure 3A and Figure 3B The timing diagram of the positive half cycle is shown in FIG. The timing diagram of the negative half cycle can refer to the timing diagram of the positive half cycle, which will not be described here.

[0066] Specifically, Figure 3A As shown, the switch tubes (i.e., S1 and S2, S3 and S4) of the same bridge arm in the DC side bridge circuit 11 are alternately turned on, and the two switch tubes (i.e., S1 and S4, S2 and S3) of different bridge arms and in the diagonal direction in the DC side bridge circuit 11 are turned on or off successively with a certain phase angle difference. Correspondingly, the control signals also present a corresponding phase angle difference. This phase angle difference is also referred to as the inner phase shift angle φ of the DC side bridge circuit 11. In this embodiment, the phase angle difference between the control signal of the switch tube S1 and the control signal of the switch tube S4 is referred to as the inner phase shift angle φ.

[0067] Please continue reading Figure 3A , the upper and lower bridge arms of the first bridge arm of the AC side bridge circuit 13 are alternately in the on or off state, wherein the states of the two switch tubes of the upper bridge arm are alternately switched, and the states of the two switch tubes of the lower bridge arm are alternately switched. Figure 2 For example, in a first time period, switch tubes S7 and S6 are turned on, and in a second time period after the first time period, switch tubes S5 and S8 are turned on.

[0068] Since the upper bridge arm and the lower bridge arm of the second bridge arm are both composed of resistors and capacitors, there is no phase shift angle between two adjacent bridge arms. However, there is a phase angle difference between the control signal of the switch tube in the DC side bridge circuit 11 and the control signal of the switch tube in the AC side bridge circuit 13, which is also called the external phase shift angle between the DC side bridge circuit 11 and the AC side bridge circuit 13. refer to Figure 3A The phase difference between the control signal of switch tube S1 and the control signal of switch tube S5 / S8 is called the external phase angle. It should be noted that in order to make the diagram concise, Figure 3A and 3B The markings in the inner phase shift angle and the outer phase shift angle are for considering the dead time (ie, the interval between S1 and S2 is the dead time). Those skilled in the art can know the inner phase shift angle and the outer phase shift angle according to the schematic diagram in the accompanying drawings.

[0069] Therefore, if Figure 4 As shown, the DC power supply 20 provides an actual input voltage v in In this case, the DC side bridge circuit 11 can convert the actual input voltage v in The conversion is performed so that a primary voltage v is generated between points a and b of the DC side bridge circuit 11. p and the primary current i p , where v p The phase shift angle (or v p The phase angle of the AC side bridge circuit 13 is equal to the internal phase shift angle φ. After the energy coupling of the transformer 12, a secondary voltage v is generated between points c and d of the AC side bridge circuit 13. s and the secondary current i s , the AC side bridge circuit 13 can convert v s Convert and output the actual output voltage v out Among them, v s With v p There will be a phase angle difference between them, which is equal to the outward phase angle

[0070] It can be understood that the rectification process of the power conversion circuit 10 is Figure 3A The inverse process of the inversion process shown in FIG. 1 is not described in detail here. Figure 4 As shown, when the power conversion circuit 10 is inverting, v p V s Leading outward phase angle When the power conversion circuit 10 is rectified, v p V s Delayed outward phase angle

[0071] It should be understood that for the above-mentioned DC side bridge circuit 11 and AC side bridge circuit 13, when switching the switch tube, it is also possible to delay a period of dead time before switching, wherein the dead time is to prevent the upper and lower switch tubes from having a risk of direct conduction. The internal phase shift angle is the proportion of S3 lagging / leading S1 relative to the period in one cycle.

[0072] Outward phase angle The ratio between the phase shift angle φ and the inner phase shift angle φ can be called the phase shift K. The value of K can be set accordingly according to the actual situation. In the embodiment of the present application, the phase shift K∈(0, 0.5].

[0073] In addition, the secondary current i of the power conversion circuit 10 s The size can be based on the actual output voltage v out 、Actual input voltage v in , turns ratio n and secondary leakage inductance L k OK. For example, Figure 4 The secondary current i in the time periods L1, L2, and L3 shown s It can be determined according to the following expression:

[0074]

[0075] The period L1 represents t0 to t1, the period L2 represents t1 to t2, and the period L3 represents t2 to t3. The maximum current value of the period L1 is i1, the maximum current value of the period L2 is i2, and the maximum current value of the period L3 is i3.

[0076] from Figure 4 It can be seen from formula (1) that the formula of period L2 is an increasing function, and the formula of period L3 is a decreasing function. Therefore, the secondary current i s The peak value (which can be referred to as the secondary side peak current) is the maximum current i2 in the time period L2.

[0077] The expression of the secondary side peak current i2 is as follows:

[0078]

[0079] Among them, f s with i s The relationship is as follows:

[0080]

[0081] Therefore, formula (2) can be further simplified as:

[0082]

[0083] After taking the derivative of φ based on formula (4), we can obtain two solutions of φ:

[0084]

[0085] It should be understood that, in the case of K∈(0, 0.5], the internal phase shift angle φ represented by equation (5) is a negative value, and therefore is unusable and discarded. The internal phase shift angle φ represented by equation (6) is a positive value within the range of K∈(0, 0.5], and therefore is valid and usable.

[0086] Therefore, we can substitute equation (6) into equation (4) and find the extreme value of the secondary peak current i2, and then convert it to obtain three solutions of K when the current stress is minimized:

[0087]

[0088] After testing, it is found that under most working conditions, the shift ratio K expressed by equation (7) is effective and usable.

[0089] In addition, the size of K will affect the zero voltage switching of the circuit 10. Therefore, to achieve zero voltage switching, K needs to satisfy the following zero voltage switching constraints:

[0090]

[0091] That is to say, K satisfies the zero voltage switching constraint only when the three inequalities in equation (10) are satisfied at the same time.

[0092] It should be understood that the above equations (1) to (10) are merely illustrative examples provided in the embodiments of the present application. In other embodiments, corresponding expressions can be established according to different power conversion circuits 10, which can be determined according to actual conditions and are all within the protection scope of the present application.

[0093] Next, the control method of the power conversion circuit of the embodiment of the present application is introduced. It is understandable that in other embodiments, it can also be implemented by a control device / electronic device / processor etc. dedicated to the power conversion circuit 10.

[0094] See also Figure 5 , the control method of the power conversion circuit provided in the embodiment of the present application includes:

[0095] Step S10: Acquire operating parameters of the power conversion circuit.

[0096] Specifically, the operating parameters of the power conversion circuit 10 may include the actual input voltage v of the DC side bridge circuit 11. in , the actual output voltage v of the AC side bridge circuit 13 out And the actual output current i out , the turns ratio n of the transformer Tr and the secondary leakage inductance L k, at least a portion of a preset shift phase range, a preset switching frequency range, etc.

[0097] Among them, the actual input voltage v in The actual output voltage v can be obtained by performing real-time voltage sampling on the second end of the DC side bridge circuit 11 or the output end of the DC power supply 20 by a voltage sampling circuit. out The voltage sampling circuit can obtain the voltage by sampling the second end of the AC side bridge circuit 13 in real time. It should be understood that when the power conversion circuit 10 is connected to the grid, the actual grid voltage can also be sampled as the actual output voltage v out The voltage sampling circuit may be independently provided or integrated into the controller 60 .

[0098] The actual output current i out The current sampling circuit can obtain the current by sampling the second end of the AC side bridge circuit 13 in real time. It should be understood that when the power conversion circuit 10 is connected to the grid, the actual output current i out and the actual output voltage v out The phase and frequency can be consistent. The current sampling circuit can be independently set or integrated into the controller 60.

[0099] The turns ratio n of the transformer Tr and the secondary leakage inductance L k These are the parameters of the components themselves and are known parameters.

[0100] The preset shift phase ratio range refers to the numerical range of the shift phase K that needs to be reached, and the preset switching frequency range refers to the switching frequency f of each switch tube in the ideal working state. s In this embodiment, the operating parameters of the power conversion circuit 10 may also include a preset voltage range. The preset voltage range includes the actual input voltage v allowed to be input to the power conversion circuit. in The numerical range of the power conversion circuit is the actual output voltage v out The numerical range of the load or the numerical range of the actual output voltage of the power conversion circuit expected by the load. For example, in this embodiment, the preset shift ratio range can be set to 0-0.5, the preset switching frequency range can be set to 30-100kHz, and the actual input voltage v in The preset voltage range is 10V~15V, and the actual output voltage v out The preset voltage range is 0~310V.

[0101] Step S20: obtaining a preset current range of the secondary peak current, a constraint relationship between the secondary peak current and the phase shift angle and the internal phase shift angle of the power conversion circuit.

[0102] The preset current range refers to the value range allowed by the secondary side peak current i2. This value range can be set according to the current stress range that is actually desired to be controlled, so that when the actual output current is within the preset current range, the current stress generated by the current will not be too large to cause device damage.

[0103] It is understandable that the power conversion circuit 10 performs power conversion under the EPS control mode, so the working condition of the power conversion circuit 10 is related to the internal phase shift angle φ and the phase shift ratio K. In other words, there will be a corresponding constraint relationship between the operating parameters of the power conversion circuit 10 and the phase shift ratio K and the internal phase shift angle φ. For example, when other operating parameters remain unchanged, there is a certain constraint relationship between the secondary side peak current i2 generated by the power conversion circuit 10 and the phase shift ratio K and the internal phase shift angle φ. The constraint relationship can be pre-stored in the internal memory or external memory of the controller 60 in the form of formulas, charts, data models, etc. Furthermore, in step S20, this constraint relationship can be obtained from the memory.

[0104] It should be understood that the execution order of step S10 and step S20 is not limited. For example, they can be executed simultaneously, or step S10 can be executed first and then step S20.

[0105] Step S30: Obtaining a target phase shift ratio and a target inner phase shift angle according to a preset current range, operating parameters and constraint relationships.

[0106] Specifically, the relevant phase shift ratio K and inner phase shift angle φ can be found according to the constraint relationship. Note that the phase shift ratio K and inner phase shift angle φ found according to the constraint relationship may be one or more. Therefore, further, the target phase shift ratio K is determined based on the acquired working condition parameters. out and the target internal phase shift angle φ out , so that the power conversion circuit 10 is at the target shift ratio K out and the target internal phase shift angle φ out During operation, the generated secondary side peak current i2 can be limited within a preset current range, thereby reducing the current value on the secondary side switch tube and preventing the peak current from being too large and causing impact damage to the switch tube.

[0107] Step S40: Calculate the target switching frequency according to the operating parameters, the target phase shift ratio, the target internal phase shift angle and the constraint relationship.

[0108] Specifically, according to the constraint relationship, it can be determined that the K out 、Target internal phase shift angle φ out The corresponding target switching frequency f out .

[0109] Step S50: generating a control signal according to the target switching frequency, the target phase shift angle and the target internal phase shift angle, wherein the control signal is used to control the output of the power conversion circuit so that the secondary side peak current is within a preset current range.

[0110] It can be understood that the switching frequency f, the phase shift ratio K and the internal phase shift angle φ are all associated with the operation of the power conversion circuit 10 and can affect the output of the power conversion circuit 10. Therefore, the control signal generated according to the target switching frequency, the target phase shift ratio and the target internal phase shift angle can effectively control the output of the power conversion circuit 10.

[0111] In general, the method of the embodiment of the present application utilizes the constraint relationship between the operating parameters of the power conversion circuit 10, the secondary side peak current, the phase shift ratio and the internal phase shift angle of the power conversion circuit 10 to obtain the target phase shift ratio and the target internal phase shift angle, and then find the target switching frequency, and finally generate a control signal according to the target switching frequency, the target phase shift ratio and the target internal phase shift angle to control the output of the power conversion circuit 10. Since the target phase shift ratio and the target internal phase shift angle obtained according to the operating parameters and the constraint relationship can limit the secondary side peak current within the preset current range, when the secondary side peak current is limited, it is avoided that the secondary side peak current is too large and causes excessive damage to the switch tube. Therefore, the method of the embodiment of the present application can control the output of the power conversion circuit 10 to reduce the peak current of the power conversion circuit 10, avoid the problem of excessive peak current damaging components and causing circuit function failure, and ensure that the normal operation of the power conversion circuit 10 is more secure.

[0112] In this embodiment, the power conversion circuit 10 adopts Figure 2 The dual active conversion circuit shown in FIG. 1 is based on which the constraint relationship between the secondary peak current i2 and the phase shift ratio K and the internal phase shift angle φ can be shown in the aforementioned formula (2). Since the aforementioned formula (2) can be converted and derived to obtain the aforementioned formulas (3) to (10), the constraint relationship includes not only formula (2) but also formulas (3) to (10) derived from formula (2).

[0113] Accordingly, see Figure 6 The process of obtaining the target phase shift angle and the target internal phase shift angle according to the preset current range, operating parameters and constraint relationship in step S30 may include:

[0114] Step S31: determining a first shift phase ratio within the preset shift phase ratio range according to the preset current range, the actual input voltage, the actual output voltage, the turns ratio, the preset shift phase ratio range and the constraint relationship.

[0115] Specifically, the actual input voltage v in 、Actual output voltage v outSubstitute the turns ratio n into equations (7) to (9) to calculate the three phase shift ratios K corresponding to the minimum secondary peak current i2 within the preset current range. Since the phase shift ratio K obtained by equations (8) and (9) exceeds the preset phase shift ratio range (0, 0.5], it is discarded. The phase shift ratio K obtained by equation (7) is within the preset phase shift ratio range (0, 0.5], so the phase shift ratio K obtained by equation (7) is used as the first phase shift ratio K1.

[0116] Step S32: determining a target internal phase shift angle according to the actual input voltage, the actual output voltage, the turns ratio, the first phase shift ratio and the constraint relationship.

[0117] Specifically, the actual input voltage v in 、Actual output voltage v out Substitute the turns ratio n and the first phase shift ratio K1 into equation (6) to calculate the target internal phase shift angle φ out .

[0118] That is,

[0119] It should be understood that due to the internal phase shift angle φ out The phase shift angle K corresponding to the minimum secondary peak current i2 is calculated. Therefore, the target internal phase shift angle φ out That is, the inner phase shift angle corresponding to the minimum secondary peak current i2. In other embodiments, the value that can satisfy the above constraint relationship can be selected as the first phase shift K according to the obtained extreme value and the allowable range, and then the corresponding target inner phase shift angle φ is obtained. out That is, the extreme point can be the optimal solution, but it is not the only solution.

[0120] Step S33: Obtaining the zero voltage switching constraint condition of the power conversion circuit.

[0121] The zero voltage switching constraint condition may be pre-stored in a memory. Then, in step S33, the zero voltage switching constraint condition may be obtained from the memory.

[0122] In this embodiment, the zero voltage switching constraint condition is related to the actual input voltage, the actual output voltage, the turns ratio and the target internal phase shift angle. For example, the zero voltage switching constraint condition can be as shown in the above formula (10), and the details can be referred to the above description, which will not be repeated here.

[0123] Step S34: determining a second phase shift angle according to the target internal phase shift angle, operating parameters and zero voltage switching constraint conditions.

[0124] Specifically, the target internal phase shift angle φ can be out and the actual input voltage v in 、Actual output voltage v outSubstitute these operating parameters, such as the turns ratio n, into equation (10), calculate the three shift phase critical values ​​of the shift phase when equation (10) is an equation, and then determine the second shift phase K2 based on the three shift phase critical values.

[0125] Among them, the calculation method of the second shift ratio K2 is not limited. For example, the three shift ratios can be taken as the maximum value of the critical value as the second shift ratio K2. For another example, the three shift ratios can be taken as the maximum value of the critical value and then added with a preset margin as the second shift ratio K2, wherein, since the calculated shift ratio is a critical value, the preset margin is set to meet the ZVS condition, and its size can be set accordingly according to the actual situation, for example, set to 0.01~0.05. For another example, the three shift ratios can be taken as the maximum value of the critical value and then multiplied by a preset ratio as the second shift ratio K2.

[0126] It should be understood that since the second shift phase ratio K2 is calculated using the shift phase critical value under the zero voltage switching constraint condition, the second shift phase ratio K2 can satisfy the zero voltage switching constraint condition.

[0127] Step S35: Determine a target shift ratio according to the first shift ratio and the second shift ratio.

[0128] Among them, the target displacement is K out The calculation method of is not limited. For example, in this embodiment, the target shift ratio can be determined according to the larger value of the first shift ratio and the second shift ratio. For further example, the larger value of the first shift ratio and the second shift ratio can be directly used as the target shift ratio K out Or, the larger value of the first shift ratio and the second shift ratio is processed by mathematical operations to obtain the target shift ratio K out Alternatively, the first shift ratio and the second shift ratio are weighted to obtain a target shift ratio.

[0129] It should be understood that due to the target shift ratio K out It is determined based on the first shift phase K1 corresponding to the minimum secondary peak current i2 and the second shift phase K2 that can meet the zero voltage switching constraint condition. Therefore, the target shift phase K out In fact, it is the optimal shift ratio after comprehensive consideration of the secondary side peak current meeting the preset current range and zero voltage switching. Moreover, the target shift ratio K out The larger value of the first shift ratio K1 and the second shift ratio K2 is determined, so that the power conversion circuit 10 can be ensured to be at the target shift ratio K out During operation, the switching device is always in a soft switching state during the on-off switching process, which can reduce power loss and improve circuit efficiency.

[0130] In general, by executing steps S31 to S35, the target phase shift ratio and target internal phase shift angle that are suitable for actual operating conditions and meet the zero voltage switching constraint conditions can be calculated, so that the power conversion circuit 10 can generate an output waveform with good sinusoidal degree when operating with the target phase shift ratio and target internal phase shift angle, and can make the secondary side peak current as small as possible within the preset current range and the switch tube achieve zero voltage switching, thereby reducing the risk of peak current impacting the switch tube and power consumption.

[0131] Moreover, the target phase shift angle and the target internal phase shift angle are related to the operating parameters. in 、Actual output voltage v out When these operating parameters change dynamically, the target phase shift ratio and the target inner phase shift angle can change accordingly. Furthermore, when the power conversion circuit 10 operates at the target phase shift ratio and the target inner phase shift angle, it can track the minimum secondary peak current in real time, so that the peak current remains small while satisfying the operating conditions, thereby reducing the impact loss on the switch tube.

[0132] Accordingly, see Figure 7 The process of calculating the target switching frequency according to the operating condition parameters, the target phase shift angle, the target internal phase shift angle and the constraint relationship in step S40 may include:

[0133] Step S41: Determine a reference switching frequency according to operating condition parameters, target internal phase shift angle, target phase shift angle and constraint relationship.

[0134] Specifically, the actual output current i can be calculated out The effective value in a single cycle of , which can be expressed as |i out |, and then the actual input voltage v in , actual output current i out The effective value of |i out |, turns ratio n and secondary leakage inductance L k These operating parameters and the target internal phase shift angle φ out , target shift ratio K out Substitute into equation (3) to calculate the reference switching frequency f ref .

[0135] That is,

[0136] Step S42: determining a switching frequency compensation value according to operating condition parameters, a target internal phase shift angle, a target phase shift angle, and a reference output voltage of the power conversion circuit.

[0137] In this embodiment, the operating parameters and the target internal phase shift angle φ can be out , target shift ratio K out , reference output voltage v refClosed-loop control is performed to adjust the switching frequency compensation value to an appropriate size.

[0138] Step S43: determining the target switching frequency according to the switching frequency compensation value and the reference switching frequency.

[0139] Specifically, the switching frequency compensation value and the reference switching frequency f ref Perform corresponding mathematical operations to obtain the target switching frequency f out The specific mathematical operation processing method can be set accordingly according to the actual situation and is not specifically limited here.

[0140] In general, by executing steps S41 to S43, the target switching frequency can be calculated so that when the power conversion circuit 10 operates at the target switching frequency, its output can meet expectations and the generated secondary side peak current can be maintained within a preset current range, thereby avoiding electrical overstress of components and circuit failure.

[0141] In one embodiment, the relevant operating parameters involved in the calculation of the switching frequency compensation value in step S42 may include: the actual input voltage v in 、Actual output voltage v out , actual output current i out The effective value of |i out |, turns ratio n and secondary leakage inductance L k .

[0142] Therefore, please refer to Figure 8 The process of determining the switching frequency compensation value according to the operating condition parameters, the target internal phase shift angle, and the reference output voltage of the power conversion circuit may include:

[0143] Step S421: performing deviation processing on the voltage difference between the reference output voltage and the actual output voltage of the AC side bridge circuit to obtain an initial current value.

[0144] Specifically, the voltage difference △v=v can be calculated first ref -v out , and then the voltage difference △v is subjected to PI (Proportion Integration) regulation or PID (Proportion Integration Differentiation) regulation or other regulation processing to obtain the initial current value i1.

[0145] Step S422: Obtain a current adjustment value according to the initial current value and the actual output current of the AC side bridge circuit.

[0146] Specifically, the initial current value i1 and the actual output current i outThe effective value of |i out | is subtracted to obtain the current adjustment value △i. In order to ensure that the current adjustment value is not less than 0, the current initial value i1 can be taken as the absolute value before participating in the calculation, so △i=|i1|-|i out |.

[0147] Step S423: determining a compensation factor according to the operating condition parameters, the target internal phase shift angle, the target phase shift angle and the constraint relationship, wherein the compensation factor is positively correlated with the product of the reference peak current and the switching frequency.

[0148] Specifically, the following formula (11) can be obtained from formula (3):

[0149]

[0150] Therefore, the actual input voltage v in , turns ratio n and secondary leakage inductance L k These operating parameters and the target internal phase shift angle φ out , target shift ratio K out Substitute into equation (3) to calculate the compensation factor. The compensation factor and i ref *f s In one embodiment, the compensation factor is equal to i ref *f s .

[0151] That is,

[0152] Step S424: performing deviation processing on the ratio between the current adjustment value and the compensation factor to obtain a switching frequency compensation value.

[0153] Specifically, we can first calculate the ratio Then the ratio PI regulation, PID regulation or other regulation processing is performed to obtain a switching frequency compensation value.

[0154] In general, in the above steps S421 to S424, the reference output voltage v ref 、Actual output voltage v out , actual output current i out 、Actual input voltage v in , turns ratio n, secondary leakage inductance L k 、Target internal phase shift angle φ out , target shift ratio K out The voltage outer loop and current inner loop are constructed by combining the constraint relationship. The switching frequency compensation value can be calculated through the voltage outer loop and the current inner loop. In this process, the deviation adjustment algorithm is used to help improve the control accuracy and control speed, which is conducive to quickly adjusting the appropriate switching frequency compensation value. It should be understood that the adjustment logic used in step S42 can be set accordingly according to actual conditions and is not limited to the implementation method mentioned in this embodiment.

[0155] In one embodiment, see Fig. 9 The process of determining the target switching frequency according to the switching frequency compensation value and the reference switching frequency in step S43 may include:

[0156] Step S431: calculating the total value between the switching frequency compensation value and the inverse of the reference switching frequency.

[0157] It can be understood that the inverse of the switching frequency is the switching period Ts, therefore, the switching frequency compensation value is a time domain characteristic parameter. The reference switching frequency f ref is a frequency domain characteristic parameter, therefore, the reference switching frequency f ref and switching frequency compensation value These two parameters need to have unified characteristics before they can participate in the calculation.

[0158] Specifically, in step S431, the reference switching frequency f ref Take the inverse so that the reference switching frequency f ref Convert to time domain characteristic parameters Then and Add them together to get the total value.

[0159] Step S432: After taking the inverse of the total value, the target switching frequency is obtained.

[0160] Due to the total value is the time domain characteristic parameter, the target switching frequency f out is a frequency domain characteristic parameter, therefore, step S432 is to convert the total value Take the inverse to get the target switching frequency f out .

[0161] That is, in other words,

[0162] In one embodiment, after the total value is taken inversely, the total value after the inverse is taken may also be After limiting, it is used as the target switching frequency f out , to prevent the target switching frequency from exceeding the preset switching frequency range.

[0163] In general, in the above steps S431 and S432, the target switching frequency f can be obtained by converting and calculating the switching frequency compensation value and the reference switching frequency. out .

[0164] Moreover, steps S431 and S432 realize the target switching frequency f out The linearization process is Such a design can achieve linear control of frequency. Compared with nonlinear control, linear control algorithm is simpler, more controllable, and more reliable in control accuracy and effect.

[0165] It can be understood that since the switching frequency compensation value and the reference switching frequency both use the same target internal phase shift angle φ out , target shift ratio K out Calculated, therefore, the target switching frequency f calculated by the switching frequency compensation value and the reference switching frequency out A small deviation is beneficial to ensuring the control effect of the power conversion circuit 10.

[0166] In the embodiment of the present application, the type of the control signal can be selected according to the actual situation. For example, in one embodiment, the control signal adopts a pulse frequency modulation (PFM) control signal.

[0167] Accordingly, the process of generating a control signal according to the target switching frequency, the target phase shift angle and the target inner phase shift angle in step S50 may include:

[0168] A pulse frequency modulation control signal is generated according to the target switching frequency, the target phase shift angle and the target internal phase shift angle. The pulse frequency modulation control signal is used to control the on-off state of the switch tube in the power conversion circuit.

[0169] It can be understood that since pulse frequency modulation has advantages in efficiency and response speed, such a design can achieve efficient and rapid control of the power conversion circuit 10 and reduce the risk of overstress damage to components.

[0170] It is worth mentioning that the method of the embodiment of the present application can control the secondary side peak current of the power conversion circuit 10 to be limited within a preset current range, thereby reducing the current stress by limiting the magnitude of the secondary side peak current. s Any one of them can control the secondary peak current (refer to formula (2)). However, the phase shift K is related to the zero voltage switching constraint of the circuit. To ensure zero voltage switching, the phase shift K cannot be set to a constant value. The internal phase shift angle φ is a multi-term in formula (2), and the analysis is very complicated. The switching frequency f sIn formula (2), is a linear term and can be set to a constant value. Therefore, the embodiment of the present application adopts a frequency modulation method to control the secondary side peak current, which can reduce the control complexity and improve the feasibility.

[0171] In addition, in order to verify the control method of the embodiment of the present application on the secondary side peak current suppression effect of the power conversion circuit 10, a simulation experiment is also conducted on the power converter circuit. Fig.10 , is a simulation waveform diagram of the power conversion circuit 10 when the control method of the embodiment of the present application is not adopted. Fig.11 , is a simulation waveform diagram of the power conversion circuit 10 when the control method of the embodiment of the present application is adopted. In these two experiments, the experimental working conditions of the power conversion circuit 10 remain the same.

[0172] Since the secondary current i s Smaller, in order to more intuitively reflect the current stress reduction effect, Fig.10 and Fig.11 The primary current i p The primary current i p and the secondary current i s The ratio between them is n:1.

[0173] from Fig.10 It can be seen that, without adopting the control method of the embodiment of the present application, the primary peak current (that is, the maximum value of the primary current) of the power conversion circuit 10 is as high as 100A. Fig.11 It can be seen that when the control method of the embodiment of the present application is adopted, the primary peak current of the power conversion circuit 10 is about 75A, which is significantly lower than 100A. Correspondingly, the secondary peak current when the control method of the embodiment of the present application is adopted will be smaller than the secondary peak current when the control method of the embodiment of the present application is not adopted. It can be seen that the control method of the embodiment of the present application can reduce the secondary peak current of the power conversion circuit 10, thereby reducing the current stress.

[0174] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should know that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously.

[0175] In addition, the controller 60 can also Fig.12 The control loop shown is implemented Figures 5 to 9 The control method of the power conversion circuit shown.

[0176] like Fig.12As shown, the controller 60 includes a first phase shift angle calculator 601, a target internal phase shift angle calculator 602, a second phase shift angle calculator 603, a maximum value (MAX) calculator 604, a compensation factor calculator 605, a first subtractor 606, a first PI regulator 607, an absolute value (ABS) calculator 608, a second subtractor 609, a first divider 610, a second PI regulator 611, a reference switching frequency calculator 612, a second divider 613, an adder 614, a third divider 615, a limiter 616 and a modulator 617.

[0177] Specifically, the actual input voltage v in 、Actual output voltage v out The first phase shift calculator 601 calculates the current range of the secondary peak current and the actual input voltage v in 、Actual output voltage v out , turns ratio n, preset phase shift ratio range and the constraint relationship between the secondary side peak current and the phase shift ratio and the inner phase shift angle to calculate the first phase shift ratio K1, and then output the first phase shift ratio K1 to the target inner phase shift angle calculator 602 and the MAX calculator 604.

[0178] The target internal phase shift angle calculator 602 calculates the phase shift angle according to the first phase shift angle K1 and the actual input voltage v in 、Actual output voltage v out , turns ratio n and constraint relationship to calculate the target internal phase shift angle φ out , and then shift the target internally by an angle φ out The output is sent to the second shift ratio calculator 603 , the compensation factor calculator 605 and the modulator 617 .

[0179] The second phase shift calculator 603 further calculates the target internal phase shift angle φ according to the target internal phase shift angle φ. out 、Actual input voltage v in 、Actual output voltage v out , turns ratio n and zero voltage switching constraint condition to calculate the second shift phase ratio K2, and then output the second shift phase ratio K2 to the MAX calculator 604.

[0180] The MAX calculator 604 selects the larger value of the first shift ratio K1 and the second shift ratio K2 by using the MAX function, and uses the larger value as the target shift ratio K1. out And output to the compensation factor calculator 605 , the reference switching frequency calculator 612 and the modulator 617 .

[0181] Actual input voltage v in , turns ratio n and secondary leakage inductance L kThe compensation factor calculator 605 then calculates the actual input voltage v in , turns ratio n, secondary leakage inductance L k 、Target internal phase shift angle φ out , target shift ratio K out Output compensation factor i ref *f s To the first divider 610.

[0182] The actual output current i out The effective value of a single cycle |i out |、Actual input voltage v in , turns ratio n and secondary leakage inductance L k The reference switching frequency calculator 612 inputs the reference switching frequency, and the reference switching frequency calculator 612 then calculates the actual output current i out The effective value of |i out |、Actual input voltage v in , turns ratio n, secondary leakage inductance L k 、Target internal phase shift angle φ out , target shift ratio K out And the constraint relationship output reference switching frequency f ref To the second divider 613. The third divider 615 divides 1 by the reference switching frequency f ref , get the inverse of the reference switching frequency And output it to adder 614.

[0183] Actual output voltage v out and the reference output voltage v ref The first subtractor 606 inputs the reference output voltage v ref The actual output voltage v out After subtraction, a voltage difference △v is obtained, and the voltage difference △v is output to the first PI regulator 607.

[0184] The first PI regulator 607 performs PI regulation on the voltage difference Δv and outputs the initial current value i1 to the ABS calculator 608. The ABS calculator 608 takes the absolute value of the initial current value i1 through the ABS function and outputs |i1| to the second subtractor 609.

[0185] The actual output current i out The effective value of |i out | is also input to the second subtractor 609, which then adds |i1| and |i out |The output current adjustment value △i after subtraction is sent to the first divider 610.

[0186] The first divider 610 further divides the current adjustment value Δi and the compensation factor i ref *f s Output ratio after division To the second PI regulator 611. The second PI regulator 611 compares the value After PI adjustment, the output switching frequency compensation value is To adder 614.

[0187] Adder 614 converts the switching frequency compensation value and the inverse of the reference switching frequency Add up to get the total value And the total value Output to the third divider 615.

[0188] The third divider 615 divides 1 by the total value Get the reciprocal of the total value And output it to limiter 616.

[0189] The limiter 616 converts the inverse of the total value After limiting, the target switching frequency f is output out To modulator 617.

[0190] The modulator 617 is configured to generate a phase shift angle φ according to the target internal phase shift angle φ. out , target shift ratio K out , target switching frequency f out A corresponding control signal is modulated, and the control signal can be output to the power conversion circuit 10 to control the output of the power conversion circuit 10 so that the secondary side peak current is within a preset current range.

[0191] It should be understood that the various links in the above control loop can also refer to the relevant description in the above method embodiment.

[0192] The control loop described above is only an illustrative example provided in this application. The specific composition of the control loop can be adjusted accordingly according to actual conditions and is not limited to the implementation method mentioned in this application.

[0193] See also Fig.13 , is a schematic diagram of a power conversion device 100 provided in an embodiment of the present application.

[0194] like Fig.13 As shown, the power conversion device 100 may include a power conversion circuit and a controller. The power conversion circuit is connected to the controller, and the controller can be used to execute the control method of the power conversion circuit, so as to control the output of the power conversion circuit and prevent excessive current stress, thereby ensuring that the power conversion circuit can operate normally.

[0195] Among them, the power conversion circuit and controller can be found in Figure 1A and Figure 2 For the relevant description in, the control method of the power conversion circuit can be found in Figures 5 to 9 The relevant description in will not be repeated here.

[0196] See also Fig.14 , is a schematic diagram of an energy storage device 1000 provided in an embodiment of the present application. The energy storage device 1000 can be applied to any energy storage system, such as a photovoltaic energy storage system, etc., which is not limited here.

[0197] like Fig.14 As shown, the energy storage device 1000 may include an energy storage battery 200 and a power conversion device 100. The power conversion device 100 and the energy storage battery 200 may be integrated or separated, which is not limited in the present embodiment.

[0198] The energy storage battery 200 can be used as a DC power source. The energy storage battery 200 is connected to the power conversion device 100 and provides DC power to the power conversion device 100. The power conversion device 100 can be Fig.13 The power conversion device 100 shown, therefore, under the control of the controller, the power conversion circuit can convert the direct current provided by the energy storage battery 200 into alternating current and output it.

[0199] See also Fig.15 , which is a schematic diagram of a power device 2000 provided in an embodiment of the present application. The power device 2000 can be applied to any electromechanical equipment product that requires power, such as a self-moving robot (such as a sweeping robot), a refrigerator, an air conditioner, an electric car, etc., which is not limited here.

[0200] like Fig.15 As shown, the power device 2000 may include a motor 300 and a power conversion device 100 . The motor 300 may serve as an AC load. The motor 300 may be connected to the power conversion device 100 and powered by the power conversion device 100 .

[0201] It is understandable that the power conversion device 100 may be Fig.13 The power conversion device 100 shown, therefore, under the control of the controller, the power conversion circuit 10 can provide the required AC power for the motor 300 and prevent the motor 300 from being impacted by excessive current stress, so that the motor 300 can start and work normally.

[0202] See also Fig.16 , shows a structural schematic diagram of an electronic device 400 provided in an embodiment of the present application.

[0203] like Fig.16As shown, electronic device 400 may include a processor 401 and a memory 402 .

[0204] The processor 401 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0205] The memory 402 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 402 may exist independently and be connected to the processor 401 via a bus. The memory 402 may also be integrated with the processor 401.

[0206] The memory 402 is used to store programs, instructions or codes for executing the above power conversion circuit control method. The processor 401 is used to execute the programs, instructions or codes stored in the memory 402. The programs, instructions or codes stored in the memory 402 can be executed. Figures 5 to 9 Part or all of the steps of the control method of the power conversion circuit in the embodiment shown in .

[0207] See also Fig.17 , shows a schematic diagram of a control device 500 for a power conversion circuit provided in an embodiment of the present application. The control device 500 for a power conversion circuit can be used to implement the control method for the power conversion circuit described above.

[0208] Specifically, Fig.17 As shown, the control device 500 of the power conversion circuit includes a first acquisition module 501 , a second acquisition module 502 , a first calculation module 503 , a second calculation module 504 and a generation module 505 .

[0209] The first acquisition module 501 is used to acquire operating parameters of the power conversion circuit.

[0210] The second acquisition module 502 is used to acquire a preset current range of the secondary peak current, a constraint relationship between the secondary peak current and the phase shift angle of the power conversion circuit and the internal phase shift angle.

[0211] The first calculation module 503 is used to obtain a target phase shift ratio and a target inner phase shift angle according to a preset current range, operating parameters and constraint relationships.

[0212] The second calculation module 504 is used to calculate the target switching frequency according to the operating condition parameters, the target phase shift ratio, the target internal phase shift angle and the constraint relationship.

[0213] The generating module 505 is used to generate a control signal according to the target switching frequency, the target phase shift angle and the target internal phase shift angle, and the control signal is used to control the output of the power conversion circuit so that the secondary side peak current is within a preset current range.

[0214] It is understandable that the division of the various modules in the above-mentioned control device 500 is only for illustration. In other embodiments, the control device 500 can be divided into different modules as needed to complete all or part of the functions of the above-mentioned control device 500.

[0215] The specific implementation of each module in the embodiment of the present application can also refer to Figures 5 to 9 The corresponding description of the method embodiment is shown, so it will not be described in detail here.

[0216] The functional modules in the embodiments of the present application may be integrated into one processing module / unit, or each module may be a separate module, or two or more modules may be integrated into one module; the above-mentioned integrated modules may be implemented in the form of hardware or in the form of hardware plus software functional modules.

[0217] If the above-mentioned integrated module of the present application is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the embodiment of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROM, RAM, magnetic disks or optical disks.

[0218] The embodiment of the present application also provides a computer-readable storage medium for storing a computer program or code. When the computer program or code is loaded and executed by the processor 401, the above Figures 5 to 9 All or part of the steps in the control method embodiment shown. Among them, computer-readable storage media include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). Specific implementations of computer-readable storage media can be found in Fig.16 The description of the memory 402 in will not be repeated here.

[0219] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. A control method for a power conversion circuit, characterized in that: The power conversion circuit includes a DC side bridge circuit, an AC side bridge circuit and a transformer, the DC side bridge circuit is connected to the primary side of the transformer, and the AC side bridge circuit is connected to the secondary side of the transformer; the control method includes: Obtaining operating parameters of the power conversion circuit; Obtaining a preset current range of a secondary side peak current, a constraint relationship between the secondary side peak current and the phase shift angle of the power conversion circuit and an internal phase shift angle; According to the preset current range, the operating condition parameters and the constraint relationship, a target phase shift ratio and a target inner phase shift angle are obtained; Calculate the target switching frequency according to the operating condition parameter, the target phase shift ratio, the target internal phase shift angle and the constraint relationship; A control signal is generated according to the target switching frequency, the target phase shift angle and the target internal phase shift angle, wherein the control signal is used to control the output of the power conversion circuit so that the secondary side peak current is within a preset current range.

2. The control method according to claim 1, characterized in that: The operating parameters at least include: the actual input voltage of the DC side bridge circuit, the actual output voltage and actual output current of the AC side bridge circuit, the turns ratio of the transformer and the preset shift ratio range; The obtaining of a target phase shift ratio and a target inner phase shift angle according to the preset current range, the operating condition parameters and the constraint relationship comprises: Determine a first shift phase ratio within the preset shift phase ratio range according to the preset current range, the actual input voltage, the actual output voltage, the turns ratio, the preset shift phase ratio range and the constraint relationship; Determine the target internal phase shift angle according to the actual input voltage, the actual output voltage, the turns ratio, the first phase shift angle, and the constraint relationship; Obtaining a zero voltage switching constraint condition of the power conversion circuit; Determine a second phase shift angle according to the target internal phase shift angle, the operating condition parameters and the zero voltage switching constraint condition; The target shift phase ratio is determined according to the first shift phase ratio and the second shift phase ratio.

3. The control method according to claim 2, characterized in that: The zero voltage switching constraint condition is related to the actual input voltage, the actual output voltage, the turns ratio, and the target internal phase shift angle.

4. The control method according to claim 2, characterized in that: The determining the target displacement ratio according to the first displacement ratio and the second displacement ratio comprises: The target shift phase ratio is determined according to a larger value of the first shift phase ratio and the second shift phase ratio.

5. The control method according to claim 1, characterized in that: The calculating the target switching frequency according to the operating condition parameter, the target phase shift ratio, the target internal phase shift angle and the constraint relationship comprises: Determine a reference switching frequency according to the operating condition parameter, the target internal phase shift angle, the target phase shift angle and the constraint relationship; Determine a switching frequency compensation value according to the operating condition parameter, the target internal phase shift angle, the target phase shift ratio, and a reference output voltage of the power conversion circuit; The target switching frequency is determined according to the switching frequency compensation value and the reference switching frequency.

6. The control method according to claim 5, characterized in that: The determining of the switching frequency compensation value according to the operating condition parameter, the target internal phase shift angle, the target phase shift ratio and the reference output voltage of the power conversion circuit comprises: Performing deviation processing on the voltage difference between the reference output voltage and the actual output voltage of the AC side bridge circuit to obtain an initial current value; Obtaining a current adjustment value according to the initial current value and the actual output current of the AC side bridge circuit; Determine a compensation factor according to the operating condition parameter, the target internal phase shift angle, the target phase shift angle and the constraint relationship; the compensation factor is positively correlated with the product of the reference peak current and the switching frequency; Deviation processing is performed on the ratio of the current adjustment value and the compensation factor to obtain the switching frequency compensation value.

7. The control method according to claim 5, characterized in that: The determining the target switching frequency according to the switching frequency compensation value and the reference switching frequency includes: calculating a total value between the switching frequency compensation value and the inverse of the reference switching frequency; After taking the reciprocal of the total value, the target switching frequency is obtained.

8. The control method according to claim 1, characterized in that: The DC side bridge circuit and the AC side bridge circuit both include a switch tube; Generating a control signal according to the target switching frequency, the target phase shift angle and the target inner phase shift angle comprises: A pulse frequency modulation control signal is generated according to the target switching frequency, the target phase shift angle and the target inner phase shift angle, and the pulse frequency modulation control signal is used to control the on-off state of the switch tube in the power conversion circuit.

9. A power conversion device, comprising a power conversion circuit and a controller, characterized in that: The controller is used to execute the control method of the power conversion circuit according to any one of claims 1 to 8.

10. An energy storage device, characterized in that: The energy storage device comprises an energy storage battery and the power conversion device as claimed in claim 9, and the energy storage battery is connected to the power conversion device to provide direct current to the power conversion device.

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