Power conversion module, overcurrent control method thereof, controller and charging system

Abstract

The invention discloses a power conversion module, an overcurrent control method thereof, a controller and a charging system, and relates to the technical field of new energy. The method comprises the steps of obtaining a load current of an output end of a power conversion module, and adjusting the output current according to a preset strategy under the condition that the output current of the power conversion module is determined to meet a preset overcurrent condition based on the load current, so that the output current meets a preset target condition; wherein the preset strategy comprises a control signal of which the frequency value is periodically increased based on a preset adjustment coefficient, and the control signal is used for adjusting the switching frequency of a switching device in the power conversion module. Therefore, when the load current is used for overcurrent control, the control precision is improved.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to a power conversion module and an overcurrent control method, a controller, and a charging system thereof. Background Art

[0002] Generally, the overcurrent control of the LLC resonant circuit output current can be achieved through current loop regulation. The current loop samples the output current of the power conversion module and adjusts it through the PI regulator to make the LLC resonant circuit work at a constant current. Among them, there are generally two positions to choose from for sampling the output current of the power conversion module, one is to sample the output current of the power converter, and the other is to sample the load current after the capacitor at the output end of the power converter.

[0003] In some special topology circuits, sampling load current for overcurrent control has certain cost and operability advantages compared to sampling output current. However, compared with output current, load current has the sluggish effect of output capacitance. Therefore, the accuracy of overcurrent control using load current is poor. Summary of the invention

[0004] The main purpose of the present application is to provide a power conversion module and its overcurrent control method, controller, and charging system, so as to improve the control accuracy when using load current for overcurrent control.

[0005] To achieve the above object, the present application provides an overcurrent control method for a power conversion module, the method being executed by a controller, and the method comprising:

[0006] Obtaining a load current at an output end of a power conversion module, and, if it is determined based on the load current that an output current of the power conversion module meets a preset overcurrent condition, adjusting the output current according to a preset strategy so that the output current meets a preset target condition;

[0007] The preset strategy includes a control signal whose output frequency value is periodically increased based on a preset adjustment coefficient, and the control signal is used to adjust the switching frequency of the switching device in the power conversion module.

[0008] Optionally, the control signal whose frequency value is periodically increased based on the preset adjustment coefficient output includes: obtaining an initial period, and reducing the initial period based on the preset adjustment coefficient to obtain a target frequency value; and generating the control signal based on the target frequency value.

[0009] Optionally, the controller includes a regulation loop, which includes a current loop and a voltage loop; obtaining the initial cycle includes: determining a first cycle through the current loop and based on the load current and the target current; determining a second cycle through the voltage loop and based on the output voltage and the target voltage of the power conversion module; and determining the smaller one of the first cycle and the second cycle as the initial cycle.

[0010] Optionally, before passing through the current loop and determining the first cycle based on the load current and the target current, the method also includes: obtaining a given current, the given current being issued by the charging system or calculated based on a power limit instruction; determining the maximum current of the power conversion module at the current output voltage, the maximum current being determined based on the current output voltage of the power conversion module and the maximum rated power at the corresponding output voltage; and determining the smaller one of the given current and the maximum current as the target current.

[0011] Optionally, the preset overcurrent condition includes at least that the current difference between the load current and the target current is not within a preset range and the frequency value determined based on the initial cycle is less than a preset maximum frequency; after obtaining the load current at the output end of the power conversion module, the method further includes: determining the current difference based on the load current and the target current; if the current difference is not within the preset range and the frequency value determined based on the initial cycle is less than the preset maximum frequency, it is determined that the output current of the power conversion module meets the preset overcurrent condition.

[0012] Optionally, the preset maximum frequency is determined when the power conversion module has a maximum input voltage and a minimum output voltage.

[0013] Optionally, determining the first period through the current loop and based on the load current and the target current includes: using a preset feedforward function and based on the output voltage of the power conversion module and the capacitance value of the output capacitor of the power conversion module, determining the current current of the output capacitor; determining the first period through the current loop and based on the load current, the target current and the current current of the output capacitor.

[0014] Optionally, the preset overcurrent condition at least includes that the current difference is not within a preset range, and the current difference is determined based on the load current, the target current and the current current of the output capacitor; after obtaining the load current at the output of the power conversion module, the method also includes: determining the current difference based on the load current, the target current and the current current of the output capacitor; if the current difference is not within the preset range, it is determined that the output current of the power conversion module meets the preset overcurrent condition.

[0015] The present application also provides a controller, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, an overcurrent control method for a power conversion module as described in any one of the above is implemented.

[0016] The present application also provides a power conversion module, comprising a controller, an inverter unit and a resonant unit as described above, wherein the controller is connected to the inverter unit and the resonant unit respectively; the controller is used to obtain the load current at the output end of the power conversion module, and when it is determined based on the load current that the output current of the power conversion module meets a preset overcurrent condition, the controller adjusts the output current according to a preset strategy so that the output current meets a preset target condition; wherein the preset overcurrent condition is used to determine whether the resonant unit is overcurrent; the preset strategy includes a control signal whose output frequency value periodically increases based on a preset adjustment coefficient, and the control signal is used to adjust the switching frequency of the switching device in the inverter unit.

[0017] The present application also provides a charging system, comprising the power conversion module as described above and at least one charging terminal; the power conversion module is connected to each of the charging terminals, and the power conversion module is used to provide the charging terminal with an output current that meets preset target conditions.

[0018] The overcurrent control method of the power conversion module of the present application obtains the load current at the output end of the power conversion module, and determines whether the output current of the power conversion module meets the preset overcurrent condition based on the load current. If it meets the condition, a control signal with a periodically increased frequency value is output based on a preset adjustment coefficient, so that the switching frequency of the switching device is increased cycle by cycle through the control signal, thereby reducing the output current of the power conversion module cycle by cycle until the output current meets the preset target condition. Therefore, by gradually adjusting the switching frequency, the problem of inaccurate clipping caused by the delay effect of the filter capacitor can be effectively avoided, thereby improving the control accuracy when using the load current for overcurrent control. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a scenario example of an overcurrent control method for a power conversion module according to an embodiment of the present application;

[0020] Figure 2 It is one of the flow charts of the overcurrent control method of the power conversion module of the embodiment of the present application;

[0021] Figure 3 This is the second flow chart of the overcurrent control method of the power conversion module of the embodiment of the present application;

[0022] Figure 4 is a schematic diagram of clipping in an embodiment of the present application;

[0023] Figure 5 This is the third flow chart of the overcurrent control method of the power conversion module of the embodiment of the present application;

[0024] Figure 6 is a schematic diagram of a voltage-current dual-loop competition regulation loop according to an embodiment of the present application;

[0025] Figure 7 This is a fourth flow chart of the overcurrent control method of the power conversion module of the embodiment of the present application;

[0026] Figure 8 is a schematic diagram of a voltage-current dual-loop competition regulation loop according to another embodiment of the present application;

[0027] Fig. 9 This is the fifth flow chart of the overcurrent control method of the power conversion module of the embodiment of the present application;

[0028] Fig.10 is a schematic diagram of an overcurrent control device of a power conversion module according to an embodiment of the present application;

[0029] Fig.11 An example of a physical structure diagram of a controller is shown;

[0030] In the figure, 110, power conversion circuit; 120, LLC resonant cavity; 130, transformer; 140, rectifier and filter unit; 150, controller; 1000, overcurrent control device of power conversion module; 1010, acquisition module; 1020, regulation control module; 1110, processor; 1120, communication interface; 1130, memory; 1140, communication bus.

[0031] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0034] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A or scheme B or schemes that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0036] In modern power electronic systems, power conversion modules are one of the indispensable core components and are widely used in industrial automation, new energy generation, electric vehicle charging and other fields. LLC resonant converters, as a high-performance AC / DC or DC / DC converter, have been widely used in power conversion modules due to their high efficiency, wide modulation range and good dynamic response characteristics. However, any complex power electronic converter may face overcurrent risks during actual operation. Therefore, overcurrent limiting technology has become the key to ensuring system reliability and extending equipment life.

[0037] In order to ensure that the LLC resonant converter can operate stably and maintain constant current output under different load conditions, current loop control technology is usually used. Current loop control technology achieves constant current output by sampling the output current of the LLC resonant converter and feeding it back to the controller, and then adjusting the control strategy according to the deviation between the actual current and the set value.

[0038] There are usually two locations to choose from for output current sampling. One is to sample the current before the output capacitor, that is, to sample the current directly at the output end of the LLC converter. This method can accurately collect the actual output current of the converter; the other is to sample after the output capacitor, that is, to sample the current at the load end. This method collects the actual current of the load. Current sampling before the output capacitor may require additional sensors and circuits, which increases the cost and sampling complexity. In contrast, the method of sampling the current after the output capacitor has certain cost advantages and is relatively simple to implement.

[0039] However, the current sampling method after the output capacitor also has obvious disadvantages. Figure 1 As shown, when the load current Io is collected, because the discharge current provided by the capacitor is superimposed on the load current, if a small load is suddenly added to the output end, the load current will be too large, that is, overcurrent will occur. If the overcurrent is not controlled and adjusted in time, it will further lead to overpower and eventually overload, causing heat damage.

[0040] In addition, because the load current is superimposed with the discharge current of the capacitor, if the load current is detected to be overcurrent, two situations may occur. One is that the load current is overcurrent, but the actual output current of the LLC converter is not overcurrent. At this time, if the modulation is performed, it may affect the normal operation of the LLC converter. The other is that the load current is overcurrent, and the actual output current of the LLC converter is also overcurrent, but because of the influence of the capacitor discharge current, when the conventional modulation strategy is adopted, if the clipping is small, it may cause the output current to still be overcurrent; if the clipping is large, it may cause the output current to be over-clipped, thereby causing the output voltage of the LLC converter to be greatly reduced, and may even be reduced to 0V. When the output is restored, the output voltage of the LLC converter will recover slowly, resulting in poor dynamic performance of the power conversion module.

[0041] In summary, compared with the output current of the LLC converter, the load current has a delay effect of the capacitor, resulting in poor dynamic response; in addition, due to the presence of the capacitor, the current waveform may be affected by the capacitor, resulting in increased difficulty in compensation; when used for overcurrent protection, the delay effect may lead to poor accuracy of the overcurrent protection.

[0042] Therefore, overcurrent control based on load current and suppressing overcurrent protection risks have always been a difficult point. Generally, overcurrent detection can be performed through the LLC resonant current transformer on the primary side to protect the safety of the hardware circuit. However, in some large dynamic test occasions, for example, in the scenario of sudden low voltage full load under wide range output high voltage, since the voltage of the capacitor cannot change suddenly, the capacitor energy will make the load current very large, even far beyond the range of the output current; as the output voltage drops, due to the slow control bandwidth speed, the PI regulator changes little in a short time, resulting in a sharp increase in the LLC resonant cavity current, which may cause the LLC converter to start overcurrent protection, thereby stopping the LLC converter from working.

[0043] To this end, the embodiments of the present application provide a power conversion module and its overcurrent control method, controller, and charging system. In the basic voltage-current dual-loop competition basic loop, the given current is adjusted in real time to avoid severe overload conditions. The overcurrent protection risk is effectively suppressed through an improved overcurrent clipping strategy, and problems such as over-clipping due to the delay effect of the filter capacitor and long dynamic recovery time are avoided, thereby improving the control accuracy when using load current for overcurrent control.

[0044] For ease of understanding, the present specification provides an example scenario of an overcurrent control method for a power conversion module. The example scenario is applied in the following example: Figure 1 In the application environment shown, the scenario example includes a power conversion circuit 110, an LLC resonant cavity 120, a transformer 130, a rectifier filter unit 140, and a controller 150. The power conversion circuit 110, the LLC resonant cavity 120, the transformer 130, and the rectifier filter unit 140 are connected in sequence, and the controller 150 is connected to the power conversion circuit 110 and the LLC resonant cavity 120, respectively.

[0045] This scenario example is mainly an application scenario of a power conversion module in a charging system. In this scenario example, the power conversion circuit 110 can be a full-bridge power conversion circuit or a half-bridge power conversion circuit. Figure 1 Taking the full-bridge power conversion circuit shown in as an example, the full-bridge power conversion circuit 110 includes four switch devices, of which two switch devices are connected in series to form an upper switch, and the other two switch devices are connected in series to form a lower switch, and the upper switch and the lower switch are connected in parallel. Among them, the switch device can be a transistor such as a MOSFET (metal-oxide semiconductor field effect transistor), an IGBT (insulated gate bipolar transistor), etc.

[0046] The LLC resonant cavity 120 includes an inductor and a capacitor connected in series; the rectifier and filter unit 140 is located on the secondary side of the transformer 130, and the rectifier and filter unit 140 may include four rectifier diodes connected in series and then in parallel, with a filter capacitor connected in parallel at its output end, and a load connected in parallel at both ends of the filter capacitor. It should be noted that the specific structure of the power conversion module in this scenario example can refer to the structure of the existing LLC converter, which will not be repeated here.

[0047] In this scenario example, the controller 150 may include an output voltage / current sampling circuit, a resonant current sampling circuit, a PWM (Pulse width modulation wave) drive circuit, and a control circuit (or a control chip). Among them, the output voltage / current sampling circuit and the resonant current sampling circuit are connected to the control circuit, and the control circuit is connected to the PWM drive circuit. The output voltage / current sampling circuit is used to collect the output current Io1 and output voltage of the power conversion module, and send the output current Io1 and output voltage to the control circuit; the resonant current sampling circuit is used to collect the current of the LLC resonant cavity 120 and send it to the control circuit; the control circuit generates a PWM signal based on the output current Io1, output voltage and current of the LLC resonant cavity 120 of the power conversion module, and then controls the switching device in the power conversion circuit 110 through the PWM drive circuit to adjust the output current Io1 of the power conversion module to limit the output current Io1.

[0048] At the same time, from Figure 1 It can also be seen that the output current Io1 of the power conversion module is superimposed with the filter capacitor Ic to obtain the load current Io. Assuming that the output current Io1 of the power conversion module is 0A at a high voltage of 500V and no-load, and a load R1 of 300V / 100A=3Ω is suddenly added, then the load current Io will quickly rise to 500V / 3Ω=167A; and the output current Io1 remains unchanged for a short time, then the equivalent circuit at this time is that the filter capacitor C1 discharges, and the current and voltage of the filter capacitor C1 decrease exponentially. Due to the energy storage delay effect of the filter capacitor C1, the load current Io will be much greater than the normal rated current (100A) for a period of time, that is, overcurrent.

[0049] With reference to the scenario example of the overcurrent control method of the power conversion module in the aforementioned embodiment, the overcurrent control method of the power conversion module in the embodiment of the present application is introduced in detail below.

[0050] Figure 2 is one of the flow charts of the overcurrent control method of the power conversion module of the embodiment of the present application. The overcurrent control method of the power conversion module can be executed by the controller in the above embodiment, such as Figure 2 As shown, the method may specifically include the following steps:

[0051] Step 210: Obtain the load current at the output end of the power conversion module.

[0052] Step 220: Determine whether the output current of the power conversion module meets the preset overcurrent condition based on the load current; if the output current of the power conversion module meets the preset overcurrent condition, execute step 230; if the output current of the power conversion module does not meet the preset overcurrent condition, end.

[0053] Step 230: Adjust the output current according to a preset strategy so that the output current meets a preset target condition.

[0054] The preset strategy includes a control signal whose output frequency value is periodically increased based on a preset adjustment coefficient, and the control signal is used to adjust the switching frequency of the switching device in the power conversion module.

[0055] like Figure 1 As shown, in this embodiment, an output voltage / current sampling circuit can be set in the controller, and the output voltage / current sampling circuit is connected to the load R1 to collect the load current Io and the output voltage Vo at the output end of the power conversion module; further, after the output voltage / current sampling circuit collects the load current Io and the output voltage Vo, it transmits these data to the control circuit (or control chip), so that the control circuit analyzes the load current Io and the output voltage Vo and executes the clipping strategy, etc.

[0056] It should be noted that the output voltage / current sampling circuit can adopt the currently existing current sampling circuit and voltage sampling circuit. For example, the output voltage sampling circuit can include a resistor divider, an isolation amplifier, and an optical coupler, etc.; the current sampling circuit can include a sampling resistor and other devices. The output voltage / current sampling circuit is not specifically limited here.

[0057] After the controller obtains the load current Io at the output end of the power conversion module, it can determine whether the output current Io1 of the power conversion module meets the preset overcurrent condition through the load current Io. It can be understood that in order to control the working current of the LLC converter, a regulation loop can be configured in the controller, and the regulation loop adjusts the current and voltage of the LLC converter by comparing the sampled value with the given value and outputting a control signal based on the comparison result until the current and voltage of the LLC converter stabilize at the given value. However, when in a scenario with a large dynamic load mutation, there is a risk of overcurrent because the regulation speed of the regulation loop is slower than the speed at which the resonant cavity current increases.

[0058] Based on this, when the controller determines that the output current Io1 of the power conversion module meets the preset overcurrent condition according to the load current Io, the controller adjusts the output current Io1 according to the preset strategy, and continuously repeats steps 210-230 until the output current Io1 meets the preset target condition. Specifically, the regulation loop inputs the sampled value and the given value into the PI regulator, and the PI regulator calculates and outputs the period of the control signal through the proportional term and the integral term. Further, the period output by the PI regulator can be processed based on the preset regulation coefficient, so that the period is reduced according to the preset regulation coefficient, and accordingly, the frequency of the control signal output by the PI regulator is increased according to the preset regulation coefficient, and finally the regulated control signal can be obtained. A PWM drive circuit is configured in the controller, and the controller controls the switching frequency of the switching device in the power conversion circuit through the PWM drive circuit and based on the regulated control signal.

[0059] It can be understood that the frequency of the control signal has a significant impact on the gain and output current Io1 of the power conversion module, especially for the LLC converter, the frequency of the control signal directly affects the gain characteristics and output current Io1 of the LLC converter. In the LLC converter, the frequency of the control signal determines the working mode of the converter. The LLC converter has an inherent resonant frequency. At this frequency, the gain of the LLC converter is the largest. However, when the frequency of the control signal is lower than the inherent resonant frequency, the inductive reactance of the inductor in the LLC converter decreases and the capacitive reactance of the capacitor increases, making the LLC converter easier to approach a pure resistance state, and the gain increases accordingly. In this case, the output current Io1 will also increase. When the frequency of the control signal is higher than the inherent resonant frequency, the inductive reactance of the inductor in the LLC converter increases and the capacitive reactance of the capacitor decreases, making the impedance of the LLC converter increase and the gain decreases accordingly. In this case, the output current Io1 will also decrease. Therefore, when the output current Io1 is over-current controlled, the frequency of the control signal is mainly increased to reach the inherent resonant frequency of the LLC converter.

[0060] After each adjustment of the output current Io1, the load current Io is obtained again, and the output current Io1 of the power conversion module is judged whether it meets the preset target condition according to the load current Io. If the output current Io1 does not meet the preset target condition, the output current Io1 is adjusted according to the preset strategy, and the process is repeated until the output current Io1 meets the preset target condition. If the output current Io1 meets the preset target condition after one adjustment, the adjustment process can be ended directly.

[0061] Therefore, the embodiment of the present application sets a preset adjustment coefficient and periodically increases the frequency of the control signal based on the preset adjustment coefficient, which not only can realize overcurrent control of the power conversion module, but also can avoid over-clipping, thereby improving the control accuracy when using the load current Io for overcurrent control.

[0062] Figure 3 FIG. 2 is a second flow chart of the overcurrent control method of the power conversion module of the embodiment of the present application. Figure 3 As shown, in some embodiments, the controller includes a regulation loop and a signal generator, the regulation loop is connected to the signal generator, and outputs a control signal with a periodically increased frequency value based on a preset regulation coefficient, which may include the following steps:

[0063] Step 310: Obtain an initial period, and reduce the initial period based on a preset adjustment coefficient to obtain a target frequency value.

[0064] Step 320: Generate a control signal based on the target frequency value.

[0065] It should be noted that the initial cycle can be obtained through the regulation loop, and the control signal can be generated through the signal generator. The regulation loop and the signal generator are the key parts to achieve closed-loop control. They work together to ensure that the output of the power conversion module meets the expected set value. The regulation loop is responsible for monitoring the actual output and comparing it with the given value, and calculating the relevant parameters of the control signal through the PI regulator; the signal generator generates the corresponding PWM signal or other forms of drive signals according to the relevant parameters of the control signal output by the regulation loop to control the working state of the power conversion module.

[0066] In this embodiment, the regulation loop may be a single-loop structure with only a current loop, or a dual-loop structure with voltage and current dual-loops competing with each other. The regulation loop is not specifically limited here.

[0067] If the regulation loop is a single-loop structure with only a current loop, the regulation loop receives the load current Io sent by the output voltage / current sampling circuit, and the regulation loop then compares the load current Io with the given current value to obtain an error signal between the two; the initial period of the control signal can be calculated based on the error signal by a PI regulator. Furthermore, the initial period can be reduced based on a preset adjustment coefficient, so that the frequency of the control signal is increased, and finally the reduced target frequency value can be obtained. Finally, the target frequency value is output to the signal generator, and the signal generator generates a corresponding control signal based on the target frequency value.

[0068] If the regulation loop is a dual-loop structure in which the voltage and current dual loops compete, the regulation loop receives the load current Io and the output voltage Vo sent by the output voltage / current sampling circuit, and the regulation loop then compares the load current Io with the given current value to obtain an error signal between the two; a PI regulator can be used to calculate the period of a control signal based on the error signal. At the same time, the regulation loop compares the output voltage Vo with the given voltage value to obtain an error signal between the two; and a PI regulator is used to calculate the period of another control signal based on the error signal. Furthermore, one cycle can be selected from the two cycles, and the cycle can be reduced based on a preset adjustment coefficient, so that the frequency of the control signal is increased, and finally the reduced target frequency value can be obtained. Finally, the target frequency value is output to the signal generator, and the signal generator generates a corresponding control signal based on the target frequency value.

[0069] The controller can reduce the initial cycle based on the preset adjustment coefficient in the following manner: when the output current Io1 is adjusted for the first time by the preset strategy, the initial cycle and the preset adjustment coefficient are multiplied to obtain a reduced cycle value; after the output current Io1 is adjusted once, the load current Io is collected again, and if it is determined based on the load current Io that the output current Io1 of the power conversion module still meets the preset overcurrent condition, the output current Io1 is adjusted again using the preset strategy, and at this time, the reduced cycle value and the preset adjustment coefficient are multiplied to obtain a new, reduced cycle value. The preset strategy is repeatedly executed until the output current Io1 of the power conversion module meets the preset target condition.

[0070] Figure 4 Schematic diagram of clipping in the embodiment of the present application. Figure 4 As shown, when the period of the PI regulator output is reduced by using the preset adjustment coefficient, the period is reduced in a step-by-step manner. It should be noted that the preset adjustment coefficient can be set by the staff according to actual needs, and the range of the preset adjustment coefficient is (0,1), and the preset adjustment coefficient is not specifically limited here.

[0071] As an example, if the preset adjustment coefficient is set to 0.8, when the output current Io1 is adjusted for the first time by the preset strategy, the initial cycle of the PI regulator output is 10us, then the preset adjustment coefficient is used to reduce the initial cycle, and the reduced cycle can be 10×0.8=8us. When the output current Io1 is adjusted for the second time by the preset strategy, the preset adjustment coefficient is used to reduce the cycle, and the reduced cycle can be 8×0.8=6.4us.

[0072] Therefore, by repeating the above steps, the period of the control signal is gradually reduced, that is, the frequency of the control signal is gradually increased, thereby achieving a smooth transition of the frequency of the control signal and avoiding over-clipping; and, with this regulation strategy, the amplitude of each adjustment is smaller, and the power conversion module can respond to changes faster and have better dynamics.

[0073] Figure 5 FIG. 3 is a flowchart of an overcurrent control method of a power conversion module according to an embodiment of the present application. Figure 5 As shown, in some embodiments, the regulation loop includes a current loop and a voltage loop, and determining the initial period through the regulation loop in step 310 may include the following steps:

[0074] Step 510 : Determine a first period through the current loop based on the load current and the target current.

[0075] Step 520: Determine a second period through the voltage loop based on the output voltage of the power conversion module and the target voltage.

[0076] Step 530: Determine the smaller one of the first cycle and the second cycle as the initial cycle.

[0077] Figure 6 Schematic diagram of the voltage and current dual-loop competition regulation loop of the embodiment of the present application. Figure 6 As shown, in this embodiment, a voltage-current dual-loop competitive regulation loop can be used to implement closed-loop control and frequency-width modulation.

[0078] Specifically, the regulation loop may include a current loop and a voltage loop, wherein the current loop is used to receive the load current Io sent by the output voltage / current sampling circuit and the target current Io* sent by the charging system (or obtained by calculation), and the current loop performs a difference between the target current Io* and the load current Io to obtain the current difference between the two. The current difference is further input to the PI regulator, which calculates the first cycle through the proportional term and the integral term. The proportional term is used to quickly respond to error changes, and the integral term is used to eliminate steady-state errors.

[0079] It should be noted that the above current difference is obtained by subtracting the load current Io from the target current Io*. If the load current Io is greater than the target current Io*, the obtained current difference is a negative number.

[0080] The voltage loop is used to receive the output voltage Vo sent by the output voltage / current sampling circuit and the target voltage Vo* sent by the charging system (or obtained by calculation). The voltage loop subtracts the target voltage Vo* from the output voltage Vo to obtain the voltage difference between the two. The voltage difference is further input to the PI regulator, which calculates the second cycle through the proportional term and the integral term.

[0081] Further, the controller performs a smaller operation on the first cycle and the second cycle, that is, selects the smaller one of the first cycle and the second cycle as the initial cycle. Selecting the smaller cycle as the initial cycle, that is, selecting the smaller cycle as the adjustment basis for adjustment, can reduce the number of adjustments and improve the adjustment efficiency.

[0082] Figure 7 FIG. 4 is a flowchart of an overcurrent control method of a power conversion module according to an embodiment of the present application. Figure 7 As shown, in some implementations, before step 510, the overcurrent control method of the power conversion module may further include the following steps:

[0083] Step 710: Obtain a given current, where the given current is issued by the charging system or calculated according to a power limit instruction.

[0084] Step 720: Determine the maximum current of the power conversion module at the current output voltage, where the maximum current is determined based on the current output voltage of the power conversion module and the maximum rated power at the corresponding output voltage.

[0085] Step 730: Determine the smaller one of the given current and the maximum current as the target current Io*.

[0086] It is understandable that in scenarios where constant power output needs to be provided within a wide voltage range, the regulation strategy needs to take into account changes in the rated current at different voltage levels. Since the rated current is smaller under high voltage and larger under low voltage, if a larger target current Io* is set under high voltage, the overload suppression capability of the current loop will be weakened. When the current voltage is high, the rated output current Io1 is small. If the current load is suddenly increased, the regulation loop can be quickly suppressed. To this end, an embodiment of the present application designs a given strategy for an adaptive target current Io*.

[0087] Specifically, the controller can receive a current instruction or a power limit instruction issued by the charging system. The current instruction directly specifies the expected value of the output current Io1, and the power limit instruction specifies the maximum value of the output power. If the controller receives a current instruction, it directly uses the instruction as the given current. If the controller receives a power limit instruction, it can calculate the corresponding given current based on the current output voltage Vo.

[0088] In addition, the controller can determine the maximum current under the current output voltage Vo of a power conversion module, and the maximum current can be calculated based on the current output voltage Vo of the power conversion module and the maximum rated power under the output voltage Vo. Specifically, the maximum current can be obtained by dividing the maximum rated power by the current output voltage Vo of the power conversion module.

[0089] Finally, the smaller one of the given current and the maximum current can be selected as the target current Io* to participate in the subsequent comparison process. It can be understood that if the current voltage is relatively high, the maximum current calculated using the current rated power will be smaller. Therefore, the maximum current may be smaller than the given current, and the smaller current value is selected from the given current and the maximum current as the target current. After overload and overcurrent, the PI regulator can react and adjust in time based on the target current, thereby improving the regulation efficiency.

[0090] The above is a detailed introduction to the process of adjusting the output current according to the preset strategy in the embodiment of the present application. The following is a detailed introduction to the process of how to determine whether the output current Io1 of the power conversion module meets the preset overcurrent condition based on the load current Io in the embodiment of the present application.

[0091] In the embodiment of the present application, two preset over-current conditions are provided. Similarly, the process of determining whether the output current Io1 is over-current is also divided into two types.

[0092] In some embodiments, the first preset overcurrent condition at least includes that the current difference between the load current Io and the target current Io* is not within a preset range and the frequency value determined based on the initial cycle is less than the preset maximum frequency. After obtaining the load current Io at the output end of the power conversion module in step 210, the overcurrent control method of the power conversion module may also include: determining the current difference based on the load current Io and the target current Io*; if the current difference is not within the preset range and the frequency value determined based on the initial cycle is less than the preset maximum frequency, determining that the output current Io1 of the power conversion module meets the preset overcurrent condition.

[0093] It should be noted that in an overcurrent scenario, the load current Io is usually greater than the target current Io*. Therefore, if the current difference between the load current Io and the target current Io* is calculated by subtracting the load current Io from the target current Io*, the current difference is usually negative. At this time, a lower limit of a preset range can be set (also a negative number). If the current difference is less than the lower limit of the preset range, it is determined that the current difference is not within the preset range. On the contrary, if the current difference between the load current Io and the target current Io* is calculated by subtracting the target current Io* from the load current Io, the current difference is usually positive. At this time, an upper limit of a preset range can be set (also a positive number). If the current difference is greater than the upper limit of the preset range, it is determined that the current difference is not within the preset range.

[0094] Taking the target current Io* minus the load current Io as an example, specifically, after the controller obtains the load current Io and the target current Io*, it can first subtract the load current Io from the target current Io* to obtain the current difference between the two, and compare the current difference with the lower limit of the preset range. If the current difference is greater than or equal to the lower limit of the preset range, it is directly determined that the output current Io1 of the power conversion module does not meet the preset overcurrent condition.

[0095] In addition, after the initial period is determined through the adjustment loop, the controller calculates the corresponding frequency value according to the initial period, and then compares the frequency value corresponding to the initial period with the preset maximum frequency. If the frequency value corresponding to the initial period is greater than or equal to the preset maximum frequency, it indicates that the output current Io1 of the power conversion module is not overcurrent. At this time, it can be directly determined that the output current Io1 of the power conversion module does not meet the preset overcurrent condition; if the frequency value corresponding to the initial period is less than the preset maximum frequency, it indicates that the output current Io1 of the power conversion module may be overcurrent.

[0096] It is worth mentioning that the preset target condition can be set with reference to the preset overcurrent condition. Specifically, when the overcurrent judgment is performed with the above-mentioned preset overcurrent condition, the corresponding preset target condition can be set to the current difference between the load current Io and the target current Io* being within the preset range or the frequency value determined based on the initial cycle being greater than or equal to the preset maximum frequency. If it is detected that the adjusted output current meets the preset target condition, the cyclic adjustment process can be exited. In some embodiments, the preset range in the preset target condition and the preset range in the preset overcurrent condition may be the same or different. Preferably, the preset range in the preset overcurrent condition may be greater than the preset range in the preset target condition.

[0097] As an example, if when calculating the current difference between the load current Io and the target current Io*, the current difference is obtained by subtracting the load current Io from the target current Io*, then the obtained current difference is usually a negative number. At this time, the preset range in the preset overcurrent condition can be set to [-2,0]A, and accordingly, the preset range in the preset target condition can be set to [-1,0]A.

[0098] In some embodiments, the preset maximum frequency is determined when the power conversion module has a maximum input voltage and a minimum output voltage Vo. Specifically, the preset maximum frequency can be calculated when the input voltage is the highest and the output voltage Vo is the lowest. It is generally believed that the power conversion module is in the most unfavorable working condition when the input voltage is the highest and the output voltage Vo is the lowest; therefore, when the frequency value corresponding to the initial cycle is lower than the preset maximum frequency, an overcurrent situation is likely to occur. In some embodiments, the preset maximum frequency can also be set to be less than the frequency calculated when the input voltage is the highest and the output voltage Vo is the lowest.

[0099] As an example, when the power conversion module is connected in parallel with the highest voltage (i.e. the input voltage remains unchanged at the highest), if a 200V / 100A load is suddenly added to the output end of the power conversion module, this will be one of the worst working conditions faced by the power conversion module. We need to calculate the gain of the power conversion module and the highest operating frequency under the overcurrent margin in this case. The preset highest frequency can be less than or equal to the highest operating frequency of this limit.

[0100] In this embodiment, if the current difference between the load current Io and the target current Io* is not within the preset range, and the frequency value determined based on the initial cycle is less than the preset maximum frequency, and these two conditions are met at the same time, it is determined that the output current Io1 of the power conversion module meets the preset overcurrent condition, and clipping processing is performed at this time; otherwise, clipping processing is not performed, and the original PI loop regulation process is maintained.

[0101] Continue to refer Figure 4 , when the load current Io detected in real time exceeds the target current Io*, the current difference between the target current Io* and the load current Io is less than the lower limit of the preset range, and the frequency value determined by the initial cycle is less than the preset maximum frequency, the cycle value output by the PI regulator decreases in a step-by-step manner, that is, clipping is performed. When the above conditions are not met, clipping is no longer performed.

[0102] Therefore, by comparing the frequency value determined in the initial cycle with the preset maximum frequency, frequency-related judgment conditions are added, which makes up for the accuracy defect when using the load current Io to judge whether the output current Io1 of the power conversion module is overcurrent, thereby effectively reducing the overcurrent risk and improving the accuracy of overcurrent control using the load current Io.

[0103] In some embodiments, the second preset overcurrent condition at least includes that the current difference is not within a preset range, and the current difference is determined based on the load current Io, the target current Io*, and the current current Ic of the output capacitor C1. After obtaining the load current Io at the output of the power conversion module in step 210, the overcurrent control method of the power conversion module may also include: determining the current difference based on the load current Io, the target current Io*, and the current current Ic of the output capacitor C1; if the current difference is not within the preset range, determining that the output current Io1 of the power conversion module meets the preset overcurrent condition.

[0104] The principle of accurately judging whether the output current Io1 is overcurrent in this embodiment is as follows: using a preset feedforward function and calculating the current at the output capacitor C1 according to the current output voltage Vo of the power conversion module and the capacitance of the output capacitor C1, and then using the load current Io and the current at the output capacitor C1 to calculate the output current Io1 of the power conversion module, and finally, using the calculated output current Io1 to perform overcurrent judgment and overcurrent control. Using the calculated output current Io1 for overcurrent control has a higher control accuracy than using the load current Io for overcurrent control, thereby avoiding over-clipping.

[0105] Specifically, the controller may first use a preset feedforward function and determine the current current Ic of the output capacitor C1 according to the received output voltage Vo and the capacitance value of the output capacitor C1 of the power conversion module (i.e., the aforementioned filter capacitor). In some embodiments, the preset feedforward function may be:

[0106]

[0107] Among them, H(s) is a preset feedforward function, and its structure is a single zero and a double pole; s is the sign of the transfer function of the Laplace transform; τ2 and τ3 are two pole frequencies, which can be set by a low-pass filter. In order to suppress the high-frequency glitches and unnecessary dynamic frequencies of voltage sampling, τ2 and τ3 can be set to 5kHz and above 10kHz respectively, and τ2 and τ3 can be the same or different; τ1=1, which can achieve the same effect as differentiation; K=C, C is the capacitance value of the filter capacitor (i.e., the output capacitor C1).

[0108] As an example, if the capacitance of the output capacitor C1 is 720uF, then K = 720×10 -6 If the power conversion module adopts series-parallel switching mode, and the series and parallel capacitors are different, this value needs to be determined according to the actual state of the power conversion module. For example, when in parallel, K is 720×10 -6 , the series capacitance is reduced by 0.25 times, then K becomes 180×10 -6 .

[0109] Figure 8 FIG. 1 is a schematic diagram of a voltage-current dual-loop competition regulation loop according to another embodiment of the present application. Figure 8 As shown, in this embodiment, after the output voltage Vo of the power conversion module is input into the preset feedforward function, the preset feedforward function outputs the current current Ic of the output capacitor C1, and then the output current Io1 of the power conversion module can be obtained by subtracting the current current Ic of the output capacitor C1 from the load current Io.

[0110] Furthermore, the current difference between the target current Io* and the output current Io1 of the power conversion module may be calculated. If the current difference is not within a preset range, it is determined that the output current Io1 of the power conversion module meets a preset overcurrent condition.

[0111] It should be noted that, in the overcurrent scenario, the output current Io1 is usually greater than the target current Io*. Therefore, if the current difference between the output current Io1 and the target current Io* is calculated by subtracting the output current Io1 from the target current Io*, the current difference is usually negative. At this time, a lower limit value of a preset range (also a negative number) can be set. If the current difference is less than the lower limit value of the preset range, it is determined that the current difference is not within the preset range. On the contrary, if the current difference between the output current Io1 and the target current Io* is calculated by subtracting the target current Io* from the output current Io1, the current difference is usually positive. At this time, an upper limit value of a preset range (also a positive number) can be set. If the current difference is greater than the upper limit value of the preset range, it is determined that the current difference is not within the preset range.

[0112] Taking the target current Io* minus the output current Io1 as an example, specifically, the controller subtracts the output current Io1 from the target current Io* to obtain the current difference between the two, and compares the current difference with the lower limit of the preset range. If the current difference (ΔIo) is greater than or equal to the lower limit of the preset range, it is directly determined that the output current Io1 of the power conversion module does not meet the preset overcurrent condition; if the current difference is less than the lower limit of the preset range, it is directly determined that the output current Io1 of the power conversion module meets the preset overcurrent condition.

[0113] In this embodiment, if the current difference between the output current Io1 and the target current Io* is not within the preset range, it is determined that the output current Io1 of the power conversion module meets the preset overcurrent condition, and clipping processing is performed at this time; otherwise, clipping processing is not performed and the original PI loop regulation process is maintained.

[0114] Because the output current Io1 of the power conversion module obtained by calculation is accurate, the overcurrent judgment and overcurrent control using the output current Io1 are more accurate, and it also makes up for the accuracy defect when using the load current Io to judge whether the output current Io1 of the power conversion module is overcurrent, thereby effectively reducing the overcurrent risk and improving the accuracy of overcurrent control using the load current Io.

[0115] It is worth mentioning that when the overcurrent judgment is performed with the second preset overcurrent condition (i.e., the current difference is not within the preset range), the corresponding preset target condition can be set as: the current difference determined based on the load current Io, the target current Io* and the current current Ic of the output capacitor C1 is within the preset range. If it is detected that the adjusted output current meets the preset target condition, the cyclic adjustment process can be exited. Similarly, the preset range in the preset target condition and the preset range in the preset overcurrent condition can be the same or different. Preferably, the preset range in the preset overcurrent condition can be larger than the preset range in the preset target condition.

[0116] In this embodiment, since the input of the current loop in the regulation loop is changed, the method of determining the first period by using the current loop will also change. Fig. 9 FIG. 5 is a flowchart of the overcurrent control method of the power conversion module of the embodiment of the present application. Fig. 9 As shown, in some embodiments, step 510 determines the first period through the current loop based on the load current Io and the target current Io*, and may include the following steps:

[0117] Step 910: Determine the current of the output capacitor by using a preset feedforward function based on the output voltage of the power conversion module and the capacitance value of the output capacitor of the power conversion module.

[0118] Step 920: Determine a first period through the current loop and based on the load current, the target current, and the current of the output capacitor.

[0119] Specifically, the current loop is used to receive the load current Io sent by the output voltage / current sampling circuit, the target current Io* sent by the charging system (or obtained by calculation), and the current current Ic of the output capacitor C1 output by the preset feedforward function. Furthermore, the current loop can use the load current Io to subtract the current current Ic of the output capacitor C1 to obtain the output current Io1 of the power conversion module; the current loop then subtracts the target current Io* and the output current Io1 of the power conversion module to obtain the current difference between the two. The current difference is further input into the PI regulator, and the PI regulator calculates the first cycle through the proportional term and the integral term. The proportional term is used to quickly respond to error changes, and the integral term is used to eliminate steady-state errors.

[0120] It should be noted that the process of determining the current current Ic of the output capacitor C1 using the preset feedforward function based on the output voltage Vo of the power conversion module and the capacitance value of the output capacitor C1 of the power conversion module can refer to the process in the aforementioned embodiment and will not be repeated here.

[0121] Finally, the controller performs a smaller operation on the first cycle obtained from the current loop and the second cycle obtained from the voltage loop, that is, selects the smaller one of the first cycle and the second cycle as the initial cycle.

[0122] Therefore, a control structure of a feedforward network is added to the basic current loop structure, and the current current Ic of the output capacitor C1 is calculated by the output voltage Vo and the preset feedforward function, and then the output current Io1 of the power conversion module is obtained. The preset feedforward function can effectively overcome the problems of the output capacitor C1 being difficult to control and the difficulty in increasing the bandwidth, and can approximately achieve the effect of directly controlling the output current Io1 of the power conversion module. Through the new current loop control structure and the improved clipping strategy, clipping is faster and more reliable, and the dynamic performance is better.

[0123] On the basis of the above embodiments, the present application also provides an overcurrent control device for a power conversion module. Fig.10 It is a schematic diagram of an overcurrent control device of a power conversion module according to an embodiment of the present application.

[0124] like Fig.10 As shown, the overcurrent control device 1000 of the power conversion module may include an acquisition module 1010 and a regulation control module 1020, and the acquisition module 1010 and the regulation control module 1020 are connected.

[0125] The acquisition module 1010 is used to acquire the load current at the output end of the power conversion module; the regulation control module 1020 is used to regulate the output current according to a preset strategy when it is determined based on the load current that the output current of the power conversion module meets the preset overcurrent condition. The preset strategy includes a control signal that periodically increases the output frequency value based on a preset regulation coefficient, and the control signal is used to regulate the switching frequency of the switching device in the power conversion module.

[0126] Thus, the load current at the output end of the power conversion module is obtained by the acquisition module 1010; the adjustment control module 1020 determines whether the output current of the power conversion module meets the preset overcurrent condition based on the load current, and if it does, a control signal with a periodic increase in the frequency value is output based on the preset adjustment coefficient, so that the switching frequency of the switching device is increased cycle by cycle through the control signal, thereby reducing the output current of the power conversion module cycle by cycle until the output current meets the preset target condition. By gradually adjusting the switching frequency, the problem of inaccurate clipping caused by the delay effect of the filter capacitor can be effectively avoided, and the control accuracy when using the load current for overcurrent control is improved.

[0127] In some embodiments, the regulation control module 1020 is specifically used to: determine an initial period through a regulation loop, and reduce the initial period based on a preset regulation coefficient to obtain a target frequency value; and generate a control signal based on the target frequency value through a signal generator.

[0128] In some embodiments, the regulation control module 1020 is also specifically used to: determine the first cycle through the current loop and based on the load current and the target current; determine the second cycle through the voltage loop and based on the output voltage of the power conversion module and the target voltage; and determine the smaller one of the first cycle and the second cycle as the initial cycle.

[0129] In some embodiments, the regulation control module 1020 is also specifically used to: obtain a given current, which is issued by the charging system or calculated according to a power limit instruction; determine the maximum current of the power conversion module at the current output voltage, which is determined based on the current output voltage of the power conversion module and the maximum rated power at the corresponding output voltage; and determine the smaller of the given current and the maximum current as the target current.

[0130] In some embodiments, the regulation control module 1020 is also specifically used to: determine a current difference based on the load current and the target current; if the current difference is not within a preset range and the frequency value determined based on the initial cycle is less than a preset maximum frequency, then determine that the output current of the power conversion module meets a preset overcurrent condition.

[0131] In some implementations, the preset maximum frequency is determined when the power conversion module has a maximum input voltage and a minimum output voltage.

[0132] In some embodiments, the regulation control module 1020 is also specifically used to: determine the current current of the output capacitor by using a preset feedforward function and based on the output voltage of the power conversion module and the capacitance value of the output capacitor of the power conversion module; determine the first period through the current loop and based on the load current, the target current and the current current of the output capacitor.

[0133] In some embodiments, the regulation control module 1020 is also specifically used to: determine the current difference based on the load current, the target current and the current current of the output capacitor; if the current difference is not within a preset range, determine that the output current of the power conversion module meets a preset overcurrent condition.

[0134] It should be noted that for details not disclosed in the overcurrent control device of the power conversion module of this embodiment, please refer to the details disclosed in the embodiment of the overcurrent control method of the power conversion module in the embodiment of this specification, and no further details will be given here.

[0135] Based on the above embodiments, the embodiments of the present application also provide a controller. Fig.11 An example of a physical structure diagram of a controller is shown below: Fig.11As shown, the controller may include: a processor 1110, a communication interface 1120, a memory 1130 and a communication bus 1140, wherein the processor 1110, the communication interface 1120 and the memory 1130 communicate with each other through the communication bus 1140. The processor 1110 may call the logic instructions in the memory 1130 to execute the overcurrent control method of the power conversion module, the method comprising: obtaining the load current at the output end of the power conversion module, and in the case of determining based on the load current that the output current of the power conversion module meets the preset overcurrent condition, adjusting the output current according to the preset strategy so that the output current meets the preset target condition; wherein the preset strategy includes a control signal that periodically increases the output frequency value based on a preset adjustment coefficient, and the control signal is used to adjust the switching frequency of the switching device in the power conversion module.

[0136] In addition, the logic instructions in the above-mentioned memory 1130 can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0137] On the basis of the above embodiments, on the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the overcurrent control method of the power conversion module provided by the above methods, the method comprising: obtaining the load current at the output end of the power conversion module, and when determining based on the load current that the output current of the power conversion module meets a preset overcurrent condition, adjusting the output current according to a preset strategy so that the output current meets a preset target condition; wherein the preset strategy comprises a control signal whose output frequency value periodically increases based on a preset adjustment coefficient, and the control signal is used to adjust the switching frequency of the switching device in the power conversion module.

[0138] On the basis of the above embodiments, the present invention also provides a power conversion module, comprising a controller, an inverter unit and a resonant unit as described in the above embodiments, the controller being connected to the inverter unit and the resonant unit respectively; the controller being used to obtain the load current at the output end of the power conversion module, and when determining based on the load current that the output current of the power conversion module meets a preset overcurrent condition, adjusting the output current according to a preset strategy so that the output current meets a preset target condition.

[0139] Among them, the preset overcurrent condition is used to determine whether the resonant unit is overcurrent; the preset target condition is used to determine whether it is possible to stop adjusting the output current; the preset strategy includes a control signal that periodically increases the output frequency value based on a preset adjustment coefficient, and the control signal is used to adjust the switching frequency of the switching device in the inverter unit.

[0140] In this embodiment, the inverter unit may be the full-bridge power conversion circuit or the half-bridge power conversion circuit in the aforementioned embodiment; the resonant unit may be the LLC resonant cavity in the aforementioned embodiment.

[0141] It should be noted that for details not disclosed in the power conversion module of this embodiment, please refer to the details disclosed in the embodiment of the overcurrent control method of the power conversion module in the embodiment of this specification, and no further details will be given here.

[0142] Based on the above embodiments, an embodiment of the present application also provides a charging system, comprising a power conversion module as described in the above embodiments and at least one charging terminal; the power conversion module is connected to each of the charging terminals, and the power conversion module is used to provide the charging terminal with an output current that meets preset target conditions.

[0143] In the embodiment of the present application, the charging terminal may be a charging gun or a terminal device with a charging gun, which can realize DC fast charging in conjunction with a split-type DC charger host.

[0144] It should be noted that for details not disclosed in the charging system of this embodiment, please refer to the details disclosed in the embodiment of the overcurrent control method of the power conversion module in the embodiment of this specification, which will not be repeated here.

[0145] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0146] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling an overcurrent of a power conversion module, characterized in that: The method is executed by a controller, and comprises: Obtaining a load current at an output end of a power conversion module, and, if it is determined based on the load current that an output current of the power conversion module meets a preset overcurrent condition, adjusting the output current according to a preset strategy so that the output current meets a preset target condition; The preset strategy includes a control signal whose output frequency value is periodically increased based on a preset adjustment coefficient, and the control signal is used to adjust the switching frequency of the switching device in the power conversion module.

2. The overcurrent control method of the power conversion module according to claim 1, characterized in that: The control signal whose output frequency value increases periodically based on the preset adjustment coefficient includes: Acquire an initial period, and reduce the initial period based on the preset adjustment coefficient to obtain a target frequency value; The control signal is generated based on the target frequency value.

3. The overcurrent control method of the power conversion module according to claim 2, characterized in that: The controller includes a regulating loop, and the regulating loop includes a current loop and a voltage loop; the obtaining of the initial cycle includes: determining a first period through the current loop and based on the load current and the target current; Determining a second period through the voltage loop and based on the output voltage of the power conversion module and the target voltage; A smaller one of the first period and the second period is determined as the initial period.

4. The overcurrent control method of the power conversion module according to claim 3, characterized in that: Before determining a first period based on the load current and the target current through the current loop, the method further includes: Obtaining a given current, where the given current is issued by the charging system or calculated according to a power limit instruction; Determine the maximum current of the power conversion module at the current output voltage, wherein the maximum current is determined according to the current output voltage of the power conversion module and the maximum rated power at the corresponding output voltage; A smaller one of the given current and the maximum current is determined as the target current.

5. The overcurrent control method of the power conversion module according to claim 2, characterized in that: The preset overcurrent condition at least includes that the current difference between the load current and the target current is not within a preset range and the frequency value determined based on the initial cycle is less than a preset maximum frequency; After obtaining the load current at the output end of the power conversion module, the method further includes: determining the current difference based on the load current and the target current; If the current difference is not within the preset range and the frequency value determined based on the initial cycle is less than the preset maximum frequency, it is determined that the output current of the power conversion module meets the preset overcurrent condition.

6. The overcurrent control method of the power conversion module according to claim 5, characterized in that: The preset maximum frequency is determined when the power conversion module has a maximum input voltage and a minimum output voltage.

7. The overcurrent control method of the power conversion module according to claim 3, characterized in that: The determining a first period through the current loop and based on the load current and the target current includes: Determine the current of the output capacitor by using a preset feedforward function based on the output voltage of the power conversion module and the capacitance value of the output capacitor of the power conversion module; The first period is determined by the current loop based on the load current, the target current and the current of the output capacitor.

8. The overcurrent control method of the power conversion module according to claim 7, characterized in that: The preset overcurrent condition at least includes that the current difference is not within a preset range, and the current difference is determined based on the load current, the target current and the current current of the output capacitor; After obtaining the load current at the output end of the power conversion module, the method further includes: Determining the current difference based on the load current, the target current, and the current of the output capacitor; If the current difference is not within the preset range, it is determined that the output current of the power conversion module meets a preset overcurrent condition.

9. A controller comprising a memory and a processor, wherein a computer program is stored in the memory, characterized in that: When the processor executes the program, the overcurrent control method of the power conversion module according to any one of claims 1 to 8 is implemented.

10. A power conversion module, characterized in that: The device comprises the controller, the inverter unit and the resonance unit as claimed in claim 9, wherein the controller is connected to the inverter unit and the resonance unit respectively; The controller is used to obtain the load current at the output end of the power conversion module, and when it is determined based on the load current that the output current of the power conversion module meets the preset overcurrent condition, adjust the output current according to a preset strategy so that the output current meets the preset target condition; Among them, the preset overcurrent condition is used to determine whether the resonant unit is overcurrent; the preset strategy includes a control signal whose output frequency value periodically increases based on a preset adjustment coefficient, and the control signal is used to adjust the switching frequency of the switching device in the inverter unit.

11. A charging system, characterized in that: comprising the power conversion module as claimed in claim 10 and at least one charging terminal; The power conversion module is connected to each of the charging terminals, and is used to provide the charging terminal with an output current that meets a preset target condition.

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