Control method of multi-stage power converter and multi-stage power converter system

Abstract

The invention discloses a control method of a multi-stage power converter and a multi-stage power converter system, and belongs to the field of multi-stage power converter systems. The control method of the multi-stage power converter comprises the following steps: after the multi-stage power converter is shut down and before the multi-stage power converter is restarted, obtaining the capacitor voltage of each bus capacitor in the multi-stage power converter; and under the condition that a first target capacitor voltage in the obtained capacitor voltages is greater than a first voltage threshold corresponding to the first target capacitor voltage, controlling the discharge module to work, or controlling the discharge module and a target power converter in the plurality of cascaded power converters to work. According to the control method of the multi-stage power converter, energy of multiple capacitor voltages can be concentrated to flow to the same discharge module for discharge processing, energy residues of all buses are reduced, and the stability of the bus voltages after restarting is improved.

Description

Technical Field

[0001] This application belongs to the field of power converter systems, and particularly relates to a control method for a multi-stage power converter and a multi-stage power converter system. Background Art

[0002] With the rapid development of power electronics technology, DC converters are increasingly widely used in the fields of energy and power systems. A DC converter can convert one DC power supply into another DC power supply with a different voltage. To meet a wider range of voltage requirements, a common technical means in engineering is to cascade multiple DC converters to achieve a wider voltage regulation range. When multiple DC converters are cascaded, there are input buses, intermediate buses, and output buses. Bus capacitors are often connected to each bus to store energy during power conversion and reduce power fluctuations. However, after the multi-stage cascaded DC converter is shut down, there will be residual energy in the bus capacitors. If this residual energy is not effectively managed after the multi-stage cascaded DC converter is shut down, when the multi-stage cascaded DC converter is restarted, this residual energy may be suddenly released, causing voltage instability and affecting the stable operation of the multi-stage cascaded DC converter. Summary of the Invention

[0003] This application aims to solve at least one of the technical problems existing in the related art. For this purpose, this application proposes a control method for a multi-stage power converter and a multi-stage power converter system, which can achieve the energy of the capacitor voltages of one or more capacitors to flow centrally to the same discharge module for centralized discharge processing through the target power converter, reduce the energy residue of each bus capacitor, improve the stability of the bus voltage after restart, and thus improve the operation stability of the multi-stage power converter.

[0004] In a first aspect, this application provides a control method for a multi-stage power converter. The multi-stage power converter includes a plurality of cascaded power converters. The multi-stage power converter is connected to positive and negative buses, and a plurality of bus capacitors are connected between the positive and negative buses. Among them, a first bus capacitor is arranged before the first end of the multi-stage power converter, a second bus capacitor is arranged after the second end of the multi-stage power converter, and a third bus capacitor is arranged between any adjacent power converters; a discharge module is connected in parallel to any one of the bus capacitors; the method includes:

[0005] After the multi-stage power converter is shut down and before it is restarted, obtain the capacitor voltages of the bus capacitors in the multi-stage power converter;

[0006] When there is a first target capacitor voltage greater than the first voltage threshold corresponding to the first target capacitor voltage among the obtained capacitor voltages, control the discharge module to operate, or control the discharge module and the target power converter among the multiple cascaded power converters to operate. The target power converter is used to control the energy flow of the bus capacitor corresponding to the first target capacitor voltage to the discharge module to release the first target capacitor voltage.

[0007] According to the control method of the multi-stage power converter of the present application, after the multi-stage power converter is shut down and before it is restarted, the capacitor voltages of each bus capacitor in the multi-stage power converter are obtained. When there is one or more capacitor voltages greater than the first voltage threshold corresponding to the one or more capacitor voltages among the obtained capacitor voltages, by controlling the discharge module to operate, or controlling the target power converter to operate, to control the energy flow of the bus capacitor corresponding to the one or more capacitor voltages to the discharge module. When controlling the discharge module to operate to release the first target capacitor voltage, it is possible to concentrate the energy of the one or more capacitor voltages to flow to the same discharge module for centralized discharge processing through the target power converter, so that the one or more capacitor voltages are less than their respective corresponding voltage thresholds, thereby reducing the energy residue of each bus capacitor after the multi-stage power converter is shut down and before it is restarted, improving the stability of the bus voltage after restart, and thus improving the operation stability of the multi-stage power converter.

[0008] According to an embodiment of the present application, when there is a first target capacitor voltage greater than the first voltage threshold corresponding to the first target capacitor voltage among the obtained capacitor voltages, controlling the discharge module to operate, or controlling the discharge module and the target power converter among the multiple cascaded power converters to operate, includes:

[0009] Based on the connection relationship between the bus capacitor corresponding to the first target capacitor voltage and the discharge module, determine the control object; the control object includes the discharge module, or the target power converter and the discharge module;

[0010] Control the control object to operate.

[0011] According to an embodiment of the present application, the determining the control object based on the connection relationship between the bus capacitor corresponding to the first target capacitor voltage and the discharge module includes:

[0012] When the bus capacitor corresponding to the first target capacitor voltage is connected in parallel with the discharge module, determine the control object as the discharge module;

[0013] When the bus capacitor corresponding to the first target capacitor voltage is not in parallel with the discharge module, determine that the control object is the target power converter and the discharge module.

[0014] According to an embodiment of the present application, the discharge module includes a switch module and at least one discharge element connected in series; controlling the operation of the discharge module includes:

[0015] Control the switch module to close.

[0016] According to an embodiment of the present application, controlling the operation of the target power converter in the plurality of cascaded power converters includes:

[0017] According to the first target capacitor voltage, control the duty cycle of the target power converter; the target power converter is determined based on the target flow direction, and the energy of the bus capacitor corresponding to the first target capacitor voltage flows to the target power converter along the target flow direction; the target flow direction is determined according to the topology of the multi-stage power converter and the installation position of the discharge module.

[0018] According to an embodiment of the present application, the controlling the duty cycle of the target power converter according to the first target capacitor voltage includes:

[0019] Based on the difference between the first target capacitor voltage and the second voltage threshold corresponding to the first target capacitor voltage, determine the target duty cycle;

[0020] Based on the target duty cycle, control the operation of the target power converter; the second voltage threshold corresponding to the first target capacitor voltage is less than the first voltage threshold corresponding to the first target capacitor voltage.

[0021] According to an embodiment of the present application, after controlling the operation of the target power converter based on the target duty cycle, the method further includes:

[0022] When the first target capacitor voltage is less than the first voltage threshold corresponding to the first target capacitor voltage, control the target power converter to stop operating.

[0023] According to an embodiment of the present application, the controlling the operation of the discharge module and the target power converter in the plurality of cascaded power converters includes:

[0024] Control the target power converter corresponding to the bus capacitor corresponding to the first target capacitor voltage to operate according to the first target capacitor voltage;

[0025] When the next bus capacitor cascaded with the target power converter is not connected in parallel with the discharge module, and when the capacitor voltage of the next bus capacitor is greater than a first voltage threshold corresponding to the capacitor voltage of the next bus capacitor, the target power converter corresponding to the next bus capacitor is controlled to operate based on the capacitor voltage of the next bus capacitor;

[0026] When the next bus capacitor cascaded with the target power converter is connected in parallel with the discharge module, and when the capacitor voltage of the next bus capacitor is greater than a first voltage threshold corresponding to the capacitor voltage of the next bus capacitor, the discharge module is controlled to operate.

[0027] According to an embodiment of the present application, after controlling the discharge module to operate when there is a first target capacitor voltage greater than a first voltage threshold corresponding to the first target capacitor voltage among the obtained capacitor voltages, the method further includes:

[0028] When all the capacitor voltages are less than the first voltage thresholds corresponding to the capacitor voltages, the discharge module is controlled to stop operating.

[0029] According to an embodiment of the present application, the first voltage thresholds corresponding to the bus capacitors are determined based on the connection positions of the bus capacitors in the multi-stage power converter.

[0030] In a second aspect, the present application provides a multi-stage power converter system, including:

[0031] A plurality of cascaded power converters, the plurality of cascaded power converters being connected to positive and negative buses;

[0032] A plurality of bus capacitors, the plurality of bus capacitors being connected between the positive and negative buses, wherein a first bus capacitor is disposed before the first end of the multi-stage power converter, a second bus capacitor is disposed after the second end of the multi-stage power converter, and a third bus capacitor is disposed between any adjacent power converters;

[0033] A discharge module, the discharge module being connected in parallel with any one of the bus capacitors;

[0034] The multi-stage power converter system operates based on the control method of the multi-stage power converter as described in the first aspect.

[0035] For the multi-stage power converter system according to the present application, after the multi-stage power converter is shut down and before it is restarted, the capacitor voltages of each bus capacitor in the multi-stage power converter are acquired. When one or more of the acquired capacitor voltages are greater than the first voltage threshold corresponding to the one or more capacitor voltages, by controlling the discharge module to operate or controlling the target power converter to operate, the energy of the bus capacitor corresponding to the one or more capacitor voltages is controlled to flow to the discharge module. When controlling the discharge module to operate to release the first target capacitor voltage, it is possible to concentrate the energy of the one or more capacitor voltages to flow to the same discharge module for centralized discharge processing through the target power converter, so that the one or more capacitor voltages are less than their respective corresponding voltage thresholds, thereby reducing the energy residue of each bus capacitor after the multi-stage power converter is shut down and before it is restarted, improving the stability of the bus voltage after restart, and thus improving the operation stability of the multi-stage power converter.

[0036] According to an embodiment of the present application, the discharge module includes:

[0037] A switch module;

[0038] At least one discharge element, and the at least one discharge element is connected in series with the switch module.

[0039] According to an embodiment of the present application, the power converter includes:

[0040] A subtractor, and two input terminals of the subtractor are respectively used to receive the first target capacitor voltage and the second voltage threshold corresponding to the first target capacitor voltage;

[0041] A regulator, the input terminal of the regulator is connected to the output terminal of the subtractor, and the output terminal of the regulator is used to output a target duty cycle.

[0042] In a third aspect, the present application provides a non-transitory computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the control method of the multi-stage power converter as described in the first aspect above.

[0043] In a fourth aspect, the present application provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the control method of the multi-stage power converter as described in the first aspect above.

[0044] One or more of the above technical solutions in the embodiments of the present application have at least one of the following technical effects:

[0045] After the multi-level power converter is shut down and before it is restarted, the capacitor voltages of each bus capacitor in the multi-level power converter are obtained. When one or more of the obtained capacitor voltages are greater than the first voltage threshold corresponding to the one or more capacitor voltages, by controlling the discharge module to operate or controlling the target power converter to operate, the energy flow of the bus capacitor corresponding to the one or more capacitor voltages is controlled to flow to the discharge module. When controlling the discharge module to operate to release the first target capacitor voltage, it is possible to concentrate the energy of the one or more capacitor voltages through the target power converter to flow to the same discharge module for centralized discharge processing, so that the one or more capacitor voltages are less than their respective corresponding voltage thresholds, thereby reducing the energy residue of each bus capacitor after the multi-level power converter is shut down and before it is restarted, improving the stability of the bus voltage after restart, and thus improving the operating stability of the multi-level power converter.

[0046] Furthermore, based on the connection relationship between the bus capacitor corresponding to the first target capacitor voltage and the discharge module, the control object is determined, and then the control object is controlled to operate, so that the effective release of the energy of the bus capacitor can be achieved, and the reliability of the control of the release of the residual energy of the bus in the multi-level power converter can be improved.

[0047] Still further, when the bus capacitor corresponding to the first target capacitor voltage is in parallel with the discharge module, the control object is determined to be the discharge module. When the condition that the bus capacitor corresponding to the first target capacitor voltage is in parallel with the discharge module is not satisfied, the control objects are determined to be the target power converter and the discharge module. It is possible to effectively release the energy of the bus capacitors that are in parallel and not in parallel with the discharge module while only requiring one discharge module in parallel with any bus capacitor, and reduce the design cost of the system.

[0048] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0049] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, where:

[0050] Figure 1 is a schematic flowchart of a control method for a multi-level power converter provided by an embodiment of the present application;

[0051] Figure 2 is a schematic structural diagram of a multi-level power converter system provided by an embodiment of the present application;

[0052] Figure 3 is a schematic structural diagram of a multi-level power converter system provided by an embodiment of the present application;

[0053] Figure 4 It is the third schematic structural diagram of the multi-level power converter system provided by the embodiment of the present application;

[0054] Figure 5 It is the fourth schematic structural diagram of the multi-level power converter system provided by the embodiment of the present application;

[0055] Figure 6 It is the fifth schematic structural diagram of the multi-level power converter system provided by the embodiment of the present application;

[0056] Figure 7 It is the sixth schematic structural diagram of the multi-level power converter system provided by the embodiment of the present application;

[0057] Figure 8 It is the schematic structural diagram of the control device of the multi-level power converter provided by the embodiment of the present application;

[0058] Figure 9 It is the schematic structural diagram of the electronic device provided by the embodiment of the present application. Specific Embodiments

[0059] Next, the technical solutions in the embodiments of the present application will be clearly described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0060] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that such used data may be interchanged under appropriate circumstances so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. generally belong to the same category, and the number of objects is not limited. For example, the first object may be one or multiple. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means an "or" relationship between the associated objects before and after.

[0061] Next, in conjunction with the accompanying drawings, the control method of the multi-level power converter, the multi-level power converter system, the electronic device, and the readable storage medium provided by the embodiments of the present application will be described in detail through specific embodiments and their application scenarios.

[0062] Among them, the control method of the multi-level power converter can be applied to a terminal, and specifically can be executed by hardware or software in the terminal.

[0063] The terminal includes, but is not limited to, portable communication devices such as mobile phones or tablet computers. It should also be understood that in some embodiments, the terminal may not be a portable communication device but a desktop computer.

[0064] The control method of the multi-level power converter provided by the embodiments of the present application. The execution subject of the control method of the multi-level power converter can be the multi-level power converter or a functional module or functional entity in the multi-level power converter that can implement the control method of the multi-level power converter. Hereinafter, taking the multi-level power converter as the execution subject as an example, the control method of the multi-level power converter provided by the embodiments of the present application will be described.

[0065] As Figure 1 shown, the control method of the multi-level power converter includes: step 110 and step 120.

[0066] Step 110: After the multi-level power converter shuts down and before it restarts, obtain the capacitor voltages of each bus capacitor in the multi-level power converter;

[0067] In this step, as Figure 2 shown, the multi-level power converter includes a plurality of cascaded power converters. The multi-level power converter is connected to the positive and negative buses, and a plurality of bus capacitors are connected between the positive and negative buses. Among them, the first bus capacitor is arranged before the first end of the multi-level power converter, the second bus capacitor is arranged after the second end of the multi-level power converter, and the third bus capacitor is arranged between any adjacent power converters. Any one of the bus capacitors is connected in parallel with a discharge module.

[0068] Among them, in the case where the multi-level power converter includes two cascaded power converters, one third bus capacitor is arranged between the two cascaded power converters; in the case where the multi-level power converter includes three or more cascaded power converters, one third bus capacitor is arranged between any adjacent power converters.

[0069] It can be understood that the obtained capacitor voltages of each bus capacitor in the multi-level power converter include the capacitor voltage of the first bus capacitor, the capacitor voltage of the second bus capacitor, and the capacitor voltages of each third bus capacitor.

[0070] The discharge module is used to release the energy of the bus capacitor.

[0071] Step 120: When there is a first target capacitor voltage greater than the first voltage threshold corresponding to the first target capacitor voltage among the obtained capacitor voltages, control the discharge module to work, or control the discharge module and the target power converter in the plurality of cascaded power converters to work. The target power converter is used to control the energy flow of the bus capacitor corresponding to the first target capacitor voltage to the discharge module to release the first target capacitor voltage.

[0072] In this step, the first target capacitor voltage may include the capacitor voltages of any one or more bus capacitors.

[0073] The first voltage threshold is the capacitor voltage threshold of the bus capacitor used to determine whether the residual energy in the bus capacitor will affect the operation stability of the multi-level power converter when the multi-level power converter restarts after shutdown.

[0074] Among them, after the multi-level power converter shuts down, if the capacitor voltage of the bus capacitor is greater than the first voltage threshold, it is considered that the residual energy in the bus capacitor affects the operation stability of the multi-level power converter when the multi-level power converter restarts; otherwise, if the capacitor voltage of the bus capacitor is less than the first voltage threshold.

[0075] In the actual execution process, each bus capacitor corresponds to its own first voltage threshold, and the first voltage thresholds corresponding to each bus capacitor may be the same or different, which can be specifically set by technicians based on engineering experience, and this application does not limit it here.

[0076] The target power converter is a power converter in multiple cascaded power converters, which is used to control the energy flow of the bus capacitor corresponding to the first target capacitor voltage to the discharge module when the first target capacitor voltage is greater than the first voltage threshold corresponding to the first target capacitor voltage.

[0077] In the actual execution process, controlling the discharge module and the target power converter in the multiple cascaded power converters to work means controlling the target power converter to work to control the energy flow of the bus capacitor corresponding to the first target capacitor voltage to the discharge module, and then controlling the discharge module to release the first target capacitor voltage so that the first target capacitor voltage is less than its corresponding first voltage threshold.

[0078] Among them, when the first target capacitor voltage includes multiple capacitor voltages, that is, when there are multiple capacitor voltages greater than their corresponding first voltage thresholds, the target power converter can control the energy flow of the bus capacitors corresponding to the multiple capacitor voltages to the discharge module, and the discharge module releases them uniformly.

[0079] It should be noted that the target power converter may include one or more of the multiple cascaded power converters. In the actual execution process, the target power converter is related to the installation position of the bus capacitor corresponding to the first target capacitor voltage in the multi-level power converter and the target flow direction of the bus energy when the first target capacitor voltage is greater than the first voltage threshold corresponding to the first target capacitor voltage.

[0080] Among them, the target flow direction is the flow direction of the pre-determined bus energy, that is, the direction flowing into the discharge module. In some embodiments, the target flow direction can be determined based on the topology of the multi-stage power converter and the installation position of the discharge module.

[0081] For example, as Figure 5 shown, when the discharge module is connected in parallel with the output bus capacitor C3 in the multi-stage power converter, the target flow direction can be determined as the direction from the input bus to the output bus. Then, when the input bus capacitor C1 is greater than its corresponding first voltage threshold, the target power converter needs to be determined as CLLC to control the bus energy of the input bus capacitor C1 to flow into the discharge module; similarly, when the intermediate bus capacitor C2 is greater than its corresponding first voltage threshold, the target power converter is BUCK. Of course, when both the input bus capacitor C1 and the intermediate bus capacitor C2 are greater than their corresponding first voltage thresholds, the target power converter can also be CLLC and BUCK.

[0082] It should be noted that in the actual execution process, the power converters included in the multi-stage power converter can be bidirectional (power flow direction) power converters or unidirectional power converters. As Figure 1 shown, if both the first power converter and the second power converter are unidirectional power converters and the power flow directions are both towards the output bus capacitor C3, then the discharge module needs to be installed at the output bus capacitor C3, and the target flow direction is the direction from the input bus capacitor C1 to the output bus capacitor C3. The same applies to the topologies of the remaining multi-stage power converters, which will not be elaborated in this application.

[0083] It can be understood that in the actual execution process, when there is any one or more bus capacitor voltages greater than their corresponding first voltage thresholds among the obtained capacitor voltages, the method of directly controlling the operation of the discharge module or the method of controlling the operation of the discharge module and the target power converter can be selected to release the first target capacitor voltage. However, the method selected in the actual execution process varies depending on the topology of the multi-stage power converter and the installation position of the discharge module.

[0084] In the research and development process, the inventor found that after the multi-stage cascaded DC converter is shut down, residual energy will remain in the bus capacitor. As a result, when the multi-stage cascaded DC converter is restarted, the magnitude of the bus voltage in the multi-stage cascaded DC converter is uncertain, and different starting duty ratios are required to adapt to different bus voltages. Otherwise, it is very easy to cause overcurrent in the equipment, increasing the complexity of control. In the related art, generally, a discharge module is added at the input or output capacitor of the multi-stage cascaded DC converter for rapid discharge, while there is often no discharge module for the intermediate bus, but it discharges slowly through self-loss. Since the energy in the intermediate bus capacitor cannot be effectively managed after shutdown, when the system is restarted, this residual energy may be suddenly released, causing voltage instability and affecting the stable operation of the system. In some embodiments, it is possible to consider adding a discharge module to the intermediate bus capacitor, but this will increase a certain cost.

[0085] In this application, after the multi-stage power converter is shut down and before it is restarted, the capacitor voltages of each bus capacitor in the multi-stage power converter are obtained. When one or more of the obtained capacitor voltages are greater than the first voltage threshold corresponding to the one or more capacitor voltages, by controlling the discharge module to operate, or by controlling the target power converter to operate, to control the energy flow of the bus capacitor corresponding to the one or more capacitor voltages to the discharge module. When controlling the discharge module to operate to release the first target capacitor voltage, it can be realized that the energy of the one or more capacitor voltages flows through the target power converter to the discharge module connected in parallel to any bus capacitor for centralized discharge processing, so that the one or more capacitor voltages are less than their respective first voltage thresholds, thereby reducing the energy residue of each bus capacitor after the multi-stage power converter is shut down and before it is restarted, improving the stability of the bus voltage after restart, and thus improving the operation stability of the multi-stage power converter.

[0086] According to the control method of the multi-level power converter provided by the embodiments of the present application, after the multi-level power converter is shut down and before it is restarted, the capacitor voltages of each bus capacitor in the multi-level power converter are obtained. When one or more of the obtained capacitor voltages are greater than the first voltage threshold corresponding to the one or more capacitor voltages, by controlling the discharge module to work, or controlling the target power converter to work, to control the energy flow of the bus capacitor corresponding to the one or more capacitor voltages to the discharge module. When controlling the discharge module to work to release the first target capacitor voltage, it can be realized that the energy of the one or more capacitor voltages flows through the target power converter to the same discharge module for centralized discharge processing, so that the one or more capacitor voltages are less than their respective corresponding voltage thresholds, thereby reducing the energy residue of each bus capacitor after the multi-level power converter is shut down and before it is restarted, improving the stability of the bus voltage after restart, and thus improving the operation stability of the multi-level power converter.

[0087] In some embodiments, step 120 may include:

[0088] Based on the connection relationship between the bus capacitor corresponding to the first target capacitor voltage and the discharge module, determine the control object;

[0089] Control the control object to work.

[0090] In this embodiment, the control object includes the discharge module, or the target power converter and the discharge module.

[0091] It can be understood that if the connection relationship between the bus capacitor corresponding to the first target capacitor voltage and the discharge module is different, the determined control object is different.

[0092] According to the control method of the multi-level power converter provided by the embodiments of the present application, based on the connection relationship between the bus capacitor corresponding to the first target capacitor voltage and the discharge module, determine the control object, and then control the control object to work, so as to effectively release the energy of the bus capacitor and improve the reliability of the control of the release of the residual energy of the bus in the multi-level power converter.

[0093] In some embodiments, based on the connection relationship between the bus capacitor corresponding to the first target capacitor voltage and the discharge module, determining the control object may include:

[0094] When the bus capacitor corresponding to the first target capacitor voltage is in parallel with the discharge module, determine the control object as the discharge module;

[0095] When the condition that the bus capacitor corresponding to the first target capacitor voltage is in parallel with the discharge module is not satisfied, determine the control object as the target power converter and the discharge module.

[0096] In this embodiment, it can be understood that when the bus capacitor corresponding to the first target capacitor voltage is connected in parallel with the discharge module, then when the first target capacitor voltage is greater than its corresponding first voltage threshold, the discharge module can be directly controlled to operate, thereby releasing the energy of the bus capacitor.

[0097] As can be seen from the description in the above embodiment, when the bus capacitor corresponding to the first target capacitor voltage is not connected in parallel with the discharge module, and when the first target capacitor voltage is greater than its corresponding first voltage threshold, since the energy of the bus capacitor corresponding to the first target capacitor voltage needs to flow to the discharge module through the control of the target power converter and then be discharged uniformly through the discharge module, thereby releasing the energy of the bus capacitor, so when the condition that the bus capacitor corresponding to the first target capacitor voltage is connected in parallel with the discharge module is not met, the control objects are determined to be the target power converter and the discharge module.

[0098] It should be noted that when the bus capacitor corresponding to the first target capacitor voltage is not connected in parallel with the discharge module, after the energy of the bus capacitor corresponding to the first target capacitor voltage flows to the discharge module through the control of the target power converter, the energy of the bus capacitor corresponding to the first target capacitor voltage is stored by the bus capacitor connected in parallel with the discharge module, and when the capacitor voltage corresponding to this bus capacitor is greater than its corresponding first voltage threshold, the discharge module starts to operate to release the energy stored in the bus capacitor connected in parallel with the discharge module, thereby achieving the effect of uniformly releasing the energy of each bus capacitor in the multi-level power converter.

[0099] According to the control method of the multi-level power converter provided by the embodiments of the present application, by determining the control object as the discharge module when the bus capacitor corresponding to the first target capacitor voltage is connected in parallel with the discharge module, and determining the control objects as the target power converter and the discharge module when the condition that the bus capacitor corresponding to the first target capacitor voltage is connected in parallel with the discharge module is not met, it is possible to effectively release the energy of the bus capacitors connected in parallel and not connected in parallel with the discharge module while only requiring one discharge module connected in parallel with any bus capacitor, and reduce the design cost of the system.

[0100] In some embodiments, the discharge module includes a switch module and at least one discharge element connected in series; controlling the discharge module to operate may include:

[0101] Controlling the switch module to close.

[0102] In this embodiment, the discharge element may include a discharge resistor, a discharge capacitor or an inductor, where the discharge resistor can release energy, and the discharge capacitor and the inductor can transfer energy.

[0103] The switching module may include a single switch, or multiple switches connected in series, or multiple switches connected in parallel.

[0104] According to the control method of the multi-level power converter provided by the embodiments of the present application, by controlling the closing of the switching module, the discharging element can be connected to both ends of the bus capacitor in parallel with the discharging module, so as to dissipate the energy (stored electric energy) of the bus capacitor, and realize the unified release of the residual energy of each bus capacitor in the multi-level power converter.

[0105] In some embodiments, controlling the operation of the target power converter in multiple cascaded power converters may include:

[0106] Controlling the duty cycle of the target power converter according to the first target capacitor voltage.

[0107] In this embodiment, based on step 120 above, it can be known that the target power converter is determined based on the target flow direction. The energy of the bus capacitor corresponding to the first target capacitor voltage flows along the target flow direction to the target power converter, and the target flow direction is determined according to the topological structure of the multi-level power converter and the installation position of the discharging module.

[0108] The duty cycle is the duty cycle of pulse width modulation (PWM) in the target power converter, and is used to control the conduction time of the switching element.

[0109] In the actual execution process, by adjusting the duty cycle of the target power converter to adjust the conduction time of the switching element, the energy flow direction of the bus capacitor corresponding to the first target capacitor voltage can be adjusted.

[0110] In some embodiments, controlling the duty cycle of the target power converter according to the first target capacitor voltage may be that the user customizes the value of the duty cycle based on engineering experience according to the first target capacitor voltage. This value is greater than 0, and the specific value is not limited in this application.

[0111] In some embodiments, the value of the duty cycle can also be controlled and adjusted based on a feedback control closed-loop system according to the first target capacitor voltage. The specific implementation will be described in the following embodiments, and will not be elaborated in this application for the time being.

[0112] In the actual execution process, the duty cycle of the target power converter can be controlled according to the first target capacitor voltage, and the energy flow direction of the bus capacitor corresponding to the first target capacitor voltage can be controlled to flow to the discharging module, that is, to the bus capacitor in parallel with the discharging module, so that the bus capacitor in parallel with the discharging module stores the energy of the bus capacitors whose capacitor voltages are greater than their first voltage thresholds, and then the discharging module performs unified release.

[0113] According to the control method of the multi-stage power converter provided by the embodiments of the present application, by controlling the duty cycle of the target power converter according to the first target capacitor voltage, it is possible to achieve discharging the energy of the bus capacitor corresponding to the first target capacitor voltage to the discharging module based on the target direction, so as to facilitate the subsequent discharging of the first bus capacitor voltage by the discharging module.

[0114] In some embodiments, controlling the duty cycle of the target power converter according to the first target capacitor voltage may include:

[0115] Determining the target duty cycle based on the difference between the first target capacitor voltage and the second voltage threshold corresponding to the first target capacitor voltage;

[0116] Controlling the operation of the target power converter based on the target duty cycle.

[0117] In this embodiment, the second voltage threshold corresponding to the first target capacitor voltage is less than the first voltage threshold corresponding to the first target capacitor voltage.

[0118] The second voltage threshold can be custom-set by the user based on engineering experience, and the present application does not limit this here.

[0119] The target duty cycle is used to control the operation of the target power converter so that the energy of the bus capacitor corresponding to the first target capacitor voltage flows to the discharging module.

[0120] Determining the target duty cycle based on the difference between the first target capacitor voltage and the second voltage threshold corresponding to the first target capacitor voltage is to control and adjust the target duty cycle based on the feedback regulation closed-loop system.

[0121] In the actual execution process, the target duty cycle can be adjusted with the goal of controlling the difference between the first target capacitor voltage and the second voltage threshold corresponding to the first target capacitor voltage to be 0, so as to adjust and control the operation of the target power converter.

[0122] It can be understood that in the process of determining the target duty cycle based on the difference between the first target capacitor voltage and the second voltage threshold corresponding to the first target capacitor voltage, the first target capacitor voltage gradually decreases, that is, the energy of the bus capacitor corresponding to the first target capacitor voltage gradually flows through the target power converter to the discharging module.

[0123] It should be noted that in the case where the target power converter includes multiple power converters, the energy of each bus capacitor whose capacitor voltage is greater than its corresponding first voltage threshold flows to the bus capacitor connected in parallel with the discharging module step by step based on the target direction.

[0124] According to the control method of the multi-level power converter provided by the embodiments of the present application, based on the difference between the first target capacitor voltage and the second voltage threshold corresponding to the first target capacitor voltage, the target duty cycle is determined, and based on the target duty cycle, the target power converter is controlled to operate. The control of the target power converter can be adjusted by adjusting the target duty cycle, so that the energy of the bus capacitor corresponding to the first target capacitor voltage gradually flows through the target power converter to the discharge module, that is, the energy of the bus capacitor corresponding to the first target capacitor voltage is transferred to the bus capacitor connected in parallel with the discharge module, improving the reliability of the control method.

[0125] In some embodiments, controlling the operation of the target power converter in the discharge module and multiple cascaded power converters may include:

[0126] Controlling the target power converter corresponding to the bus capacitor corresponding to the first target capacitor voltage to operate according to the first target capacitor voltage;

[0127] When the next bus capacitor cascaded with the target power converter is not connected in parallel with the discharge module and the capacitor voltage of the next bus capacitor is greater than the first voltage threshold corresponding to the capacitor voltage of the next bus capacitor, controlling the target power converter corresponding to the next bus capacitor to operate based on the capacitor voltage of the next bus capacitor;

[0128] When the next bus capacitor cascaded with the target power converter is connected in parallel with the discharge module and the capacitor voltage of the next bus capacitor is greater than the first voltage threshold corresponding to the capacitor voltage of the next bus capacitor, controlling the discharge module to operate.

[0129] In this embodiment, the target power converter corresponding to the next bus capacitor is also determined based on the target flow direction, which will not be elaborated here.

[0130] It can be understood that when the target power converter includes multiple power converters, that is, the capacitor voltages of multiple bus capacitors are greater than their corresponding first voltage thresholds, or during the energy transfer process, when the capacitor voltages of multiple bus capacitors are respectively greater than their corresponding first voltage thresholds, the energy of each bus capacitor with a capacitor voltage greater than its corresponding first voltage threshold flows step by step to the bus capacitor connected in parallel with the discharge module based on the target flow direction.

[0131] Next, an example will be given to illustrate the situation where, when controlling the operation of the target power converter in the discharge module and multiple cascaded power converters, the energy of each bus capacitor with a capacitor voltage greater than its corresponding first voltage threshold flows step by step to the bus capacitor connected in parallel with the discharge module based on the target flow direction.

[0132] For example, as Figure 5As shown in the figure, the multi-level power converter includes a CLLC converter and a BUCK converter. The CLLC converter and the BUCK converter are connected to the positive and negative buses. An input bus capacitor C1 is connected between the positive and negative buses at the first end of the CLLC converter. An intermediate bus capacitor C2 is connected between the positive and negative buses between the CLLC converter and the BUCK converter. An output bus capacitor C3 is connected between the positive and negative buses at the second end of the BUCK converter. The discharge module is connected in parallel with the output bus capacitor C3. That is, the target flow direction is from C1 to C3. Then, when the voltage of C1 is greater than its corresponding first voltage threshold, the CLLC converter (target power converter) operates, and the energy in C1 flows through the CLLC converter to C2; when the voltage of C2 is greater than its corresponding first voltage threshold, the BUCK converter (target power converter) operates, and the energy in C2 flows through the BUCK converter to C3; when the voltage of C3 is greater than its corresponding first voltage threshold, the switch in the discharge module closes, connecting the discharge resistor across C3, and the energy is dissipated through the discharge resistor.

[0133] Another example is, as Figure 6 As shown in the figure, the multi-level power converter includes a BUCK-BOOST converter and an LLC converter. The BUCK-BOOST converter and the LLC converter are connected to the positive and negative buses. An input bus capacitor C1 is connected between the positive and negative buses at the first end of the BUCK-BOOST converter. An intermediate bus capacitor C2 is connected between the positive and negative buses between the BUCK-BOOST converter and the LLC converter. An output bus capacitor C3 is connected between the positive and negative buses at the second end of the LLC converter. The discharge module is connected in parallel with the intermediate bus capacitor C2. That is, the target flow directions are from C1 to C2 and from C3 to C2. Then, when the voltage of C1 is greater than its corresponding first voltage threshold, the BUCK-BOOST converter operates, and the energy in C1 flows through the BUCK-BOOST converter to C2; when the voltage of C3 is greater than its corresponding first voltage threshold, the LLC converter operates, and the energy in C3 flows through the LLC converter to C2; when the voltage of C2 is greater than its corresponding first voltage threshold, the switch in the discharge module closes, connecting the discharge resistor across C2, and the energy is dissipated through the discharge resistor.

[0134] Another example is, as Figure 7As shown in the figure, the multi-stage power converter includes a CLLC converter and a BUCK converter. The CLLC converter and the BUCK converter are connected to the positive and negative busbars. An input bus capacitor C1 is connected between the positive and negative busbars at the first end of the CLLC converter. An intermediate bus capacitor C2 is connected between the positive and negative busbars between the CLLC converter and the BUCK converter. An output bus capacitor C3 is connected between the positive and negative busbars at the second end of the BUCK converter. The discharge module is connected in parallel to the input bus capacitor C1. That is, the target flow direction is from C3 to C1. Then, when the voltage of C3 is greater than its corresponding first voltage threshold, the BUCK converter operates, and the energy in C3 flows through the BUCK converter to C2; when the voltage of C2 is greater than its corresponding first voltage threshold, the CLLC converter operates, and the energy in C2 flows through the CLLC converter to C1; when the voltage of C1 is greater than its corresponding first voltage threshold, the switch in the discharge module closes, connecting the discharge resistor across C1, and the energy is dissipated through the discharge resistor.

[0135] It can be understood that whether the discharge module operates is determined based on whether the capacitor voltage of the bus capacitor connected in parallel with the discharge module is greater than its corresponding first voltage threshold. The situation where the capacitor voltage of the bus capacitor connected in parallel with the discharge module is greater than its corresponding first voltage threshold can be caused by the residual energy of this bus capacitor after the multi-stage power converter shuts down, or by the transfer of the residual energy of the bus capacitor not connected in parallel with the discharge module; the operation of the target power converter is similar to that of the discharge module, which will not be elaborated here.

[0136] According to the control method of the multi-stage power converter provided by the embodiments of the present application, by controlling the target power converter corresponding to the bus capacitor corresponding to the first target capacitor voltage to operate according to the first target capacitor voltage, and when the next bus capacitor cascaded with the target power converter is not connected in parallel with the discharge module and the capacitor voltage of the next bus capacitor is greater than the first voltage threshold, controlling the target power converter corresponding to the next bus capacitor to operate based on the capacitor voltage of the next bus capacitor, and when the next bus capacitor cascaded with the target power converter is connected in parallel with the discharge module, controlling the discharge module to operate, the step-by-step transfer of the energy of the bus capacitor corresponding to the first target capacitor voltage can be realized, so that the residual energy in the multi-stage power converter can all flow to the discharge module for centralized discharge through step-by-step transfer, thereby realizing the release of the residual energy of each bus capacitor based on the same discharge module, and improving the stability of the multi-stage power converter after the next startup.

[0137] In some embodiments, after controlling the target power converter to operate based on the target duty cycle, the method may further include:

[0138] When the first target capacitor voltage is less than the first voltage threshold corresponding to the first target capacitor voltage, control the target power converter to stop working.

[0139] In this embodiment, it can be understood that when the bus capacitor corresponding to the first target capacitor voltage is not connected in parallel with the discharge module, and when the first target capacitor voltage is greater than the first voltage threshold corresponding to the first target capacitor voltage, then control the target power converter to start working, so that the energy of the bus capacitor corresponding to the first target capacitor voltage flows to the discharge module for release, and when the first target capacitor voltage is less than the first voltage threshold corresponding to the first target capacitor voltage, control the target power converter to stop working.

[0140] Among them, as can be seen from the description in the above embodiment, in this embodiment, when the target power converter includes multiple power converters, the first target capacitor voltage includes multiple capacitor voltages, and each capacitor voltage controls the working state (working or stopping working) of the corresponding power converter

[0141] For example, continuing with Figure 5 as an example, the multilevel power converter includes a CLLC converter and a BUCK converter. The CLLC converter and the BUCK converter are connected to the positive and negative buses. An input bus capacitor C1 is connected between the positive and negative buses at the first end of the CLLC converter. An intermediate bus capacitor C2 is connected between the positive and negative buses between the CLLC converter and the BUCK converter. An output bus capacitor C3 is connected between the positive and negative buses at the second end of the BUCK converter. The discharge module is connected in parallel with the output bus capacitor C3, that is, the target flow direction is from C1 to C3. Then, when the voltage of C1 is greater than its corresponding first voltage threshold, the CLLC converter (target power converter) works, and the energy in C1 flows through the CLLC converter to C2. When the voltage of C1 is less than its corresponding first voltage threshold, the CLLC converter (target power converter) stops working; when the voltage of C2 is greater than its corresponding first voltage threshold, the BUCK converter (target power converter) works, and the energy in C2 flows through the BUCK converter to C3. When the voltage of C2 is less than its corresponding first voltage threshold, the BUCK converter (target power converter) stops working.

[0142] It should be noted that since the second voltage threshold corresponding to the first target capacitor voltage is less than the first voltage threshold corresponding to the first target capacitor voltage, when the difference between the first target capacitor voltage and its corresponding second voltage threshold is controlled to 0 to adjust the target duty cycle, that is, when the first target capacitor voltage is equal to its corresponding second voltage threshold, the first target capacitor voltage is made less than its corresponding first voltage threshold, so that while meeting the condition for the target power converter to stop working, when the multi-stage power converter restarts, the first target capacitor voltage is below the capacitor voltage threshold of the bus capacitor that will not affect the operation stability of the multi-stage power converter; if the difference between the first target capacitor voltage and its corresponding first voltage threshold is controlled to 0 to adjust the target duty cycle, there may be a risk that due to adjustment errors and other reasons, the difference between the first target capacitor voltage and its corresponding first voltage threshold is small, but the first target capacitor voltage is still greater than its corresponding first voltage threshold, and the subsequent condition for the target power converter to stop working cannot be met, let alone making the first target capacitor voltage below the capacitor voltage threshold of the bus capacitor that will not affect the operation stability of the multi-stage power converter when the multi-stage power converter restarts.

[0143] According to the control method of the multi-stage power converter provided by the embodiments of the present application, by controlling the target power converter to stop working when the first target capacitor voltage is less than the first voltage threshold corresponding to the first target capacitor voltage, after the residual energy of the bus capacitor corresponding to the first target capacitor voltage flows to the discharge module, the energy transfer of the bus capacitor corresponding to the first target capacitor voltage based on the target power converter can be stopped, reducing the control conflict between the restart of the subsequent multi-stage power converter and the function of the target power converter to transfer the residual energy of the bus, and improving the logic and reliability of the control method.

[0144] In some embodiments, when there is a situation where the first target capacitor voltage among the obtained capacitor voltages is greater than the first voltage threshold corresponding to the first target capacitor voltage, after controlling the discharge module to work, the method may further include:

[0145] When all the capacitor voltages are less than the first voltage thresholds corresponding to the respective capacitor voltages, control the discharge module to stop working.

[0146] In this embodiment, as can be seen from the above embodiment, whether the discharge module works is controlled by the bus capacitor connected in parallel with the discharge module. When the capacitor voltage of this bus capacitor is greater than its corresponding first voltage threshold, the discharge module works; when the capacitor voltage of this bus capacitor is less than its corresponding first voltage threshold, the discharge module stops working.

[0147] Among them, when the bus capacitor corresponding to the first target capacitor voltage is not connected in parallel with the discharge module, and the capacitor voltage of the bus capacitor connected in parallel with the discharge module is less than its corresponding first voltage threshold, it is the situation where the capacitor voltages of each capacitor in the multi-stage power converter are all less than the first voltage thresholds corresponding to the respective capacitor voltages (the energy of the bus capacitor corresponding to each capacitor voltage flows to the bus capacitor connected in parallel with the discharge module).

[0148] According to the control method of the multi-stage power converter provided by the embodiments of the present application, by controlling the discharge module to stop working when the capacitor voltages of each capacitor are all less than the first voltage thresholds corresponding to the respective capacitor voltages, after the residual energy of each bus capacitor in the multi-stage power converter flows to the discharge module and is released through the discharge module, the active discharge process of the multi-stage power converter can be stopped, reducing the control conflict between the subsequent restart of the multi-stage power converter and the active discharge function based on the discharge module and the target power converter, and improving the logic and reliability of the control method.

[0149] In some embodiments, the first voltage threshold corresponding to each bus capacitor is determined based on the connection position of each bus capacitor in the multi-stage power converter.

[0150] In this embodiment, when the bus capacitor is connected to the first end and the second end of the multi-stage power converter (connected to the positive and negative buses accessed by the multi-stage power converter), that is, when the bus capacitor is the first bus capacitor or the second bus capacitor, the bus capacitor is related to the external characteristics, and the first voltage threshold corresponding to the bus capacitor can be determined according to the bus capacitor specifications and regulations; when the bus capacitor is connected between any two adjacent power converters in the multi-stage power converter, that is, when the bus capacitor is the third bus capacitor, the bus capacitor is not related to the external characteristics, and the first voltage threshold corresponding to the bus capacitor can be set to any voltage value that meets the safety requirements.

[0151] According to the control method of the multi-stage power converter provided by the embodiments of the present application, by determining the first voltage threshold corresponding to each bus capacitor based on the connection position of each bus capacitor in the multi-stage power converter, the accuracy of the determined first voltage thresholds can be improved, thereby improving the accuracy of the comparison result based on the capacitor voltage of each bus capacitor and the first voltage threshold corresponding to each bus capacitor.

[0152] The embodiments of the present application also provide a multi-stage power converter system.

[0153] As Figure 2 shown, the device includes: a plurality of cascaded power converters, a plurality of bus capacitors, and a discharge module.

[0154] Among them, multiple cascaded power converters are connected to the positive and negative busbars, and multiple bus capacitors are connected between the positive and negative busbars. Among them, the first bus capacitor is arranged before the first end of the multi-stage power converter, the second bus capacitor is arranged after the second end of the multi-stage power converter, and the third bus capacitor is arranged between any adjacent power converters.

[0155] The discharge module can be connected in parallel with any one of the bus capacitors.

[0156] The multi-stage power converter system operates based on the control method of the multi-stage power converter described in any one of the above embodiments.

[0157] According to the multi-stage power converter system provided by the embodiments of the present application, after the multi-stage power converter is shut down and before it is restarted, the capacitor voltages of each bus capacitor in the multi-stage power converter are obtained. When one or more of the obtained capacitor voltages are greater than the first voltage threshold corresponding to the one or more capacitor voltages, by controlling the discharge module to operate, or controlling the target power converter to operate, to control the energy flow of the bus capacitor corresponding to the one or more capacitor voltages to the discharge module. When controlling the discharge module to operate to release the first target capacitor voltage, it is possible to achieve that the energy of the one or more capacitor voltages flows through the target power converter to the same discharge module for centralized discharge processing, so that the one or more capacitor voltages are less than their respective corresponding voltage thresholds, thereby reducing the energy residue of each bus capacitor after the multi-stage power converter is shut down and before it is restarted, improving the stability of the bus voltage after restart, and thus improving the operation stability of the multi-stage power converter.

[0158] As Figure 5 shown, in some embodiments, the discharge module may include:

[0159] A switch module;

[0160] At least one discharge element, and at least one discharge element is connected in series with the switch module.

[0161] In this embodiment, the switch module may include one switch, or multiple switches connected in series, or multiple switches connected in parallel.

[0162] The discharge element may include a discharge resistor, a discharge capacitor or an inductor. Among them, the discharge resistor can release energy, and the discharge capacitor and inductor can transfer energy.

[0163] In the actual execution process, by controlling the on and off states of the switch module, the operation of the discharge module can be controlled. Among them, when the switch module is closed, the discharge module operates, and the discharge element releases the energy of the bus capacitor. When the switch module is turned off, the discharge module stops operating.

[0164] According to the multi-level power converter system provided by the embodiments of the present application, through a discharge module including a switch module and at least one discharge element connected in series with the switch module, during actual execution, by controlling the switch module to close, the discharge element can be connected to both ends of a bus capacitor connected in parallel with the discharge module, thereby dissipating the energy of the bus capacitor and realizing the unified release of the residual energy of each bus capacitor in the multi-level power converter.

[0165] In some embodiments, the power converter may include:

[0166] A subtractor, two input terminals of the subtractor are respectively used to receive a first target capacitor voltage and a second voltage threshold corresponding to the first target capacitor voltage;

[0167] A regulator, the input terminal of the regulator is connected to the output terminal of the subtractor, and the output terminal of the regulator is used to output a target duty cycle.

[0168] In this embodiment, during actual execution, as Figure 3 or Figure 4 shown, two input terminals of the subtractor are respectively used to receive a first target capacitor voltage UbusRef and a second voltage threshold UbusFdb corresponding to the first target capacitor voltage. After calculating the difference between the first target capacitor voltage UbusRef and the second voltage threshold UbusFdb corresponding to the first target capacitor voltage by the subtractor, the difference is received by the input terminal of the regulator, and based on this difference in the regulator, the control target duty cycle is adjusted, and the target duty cycle is output at the output terminal.

[0169] According to the multi-level power converter system provided by the embodiments of the present application, through a power converter including a subtractor and a regulator connected to the subtractor, it is possible to determine the target duty cycle based on the difference between the first target capacitor voltage and the second voltage threshold corresponding to the first target capacitor voltage, thereby facilitating subsequent control of the target power converter to work based on the target duty cycle, so that the energy of the bus capacitor corresponding to the first target capacitor voltage gradually flows through the target power converter to the discharge module, facilitating subsequent unified release of the bus energy based on the discharge module.

[0170] For the control method of the multi-level power converter provided by the embodiments of the present application, the execution subject may be a control device of the multi-level power converter. In the embodiments of the present application, taking the control device of the multi-level power converter executing the control method of the multi-level power converter as an example, the control device of the multi-level power converter provided by the embodiments of the present application is described.

[0171] In some embodiments, the embodiments of the present application further provide a control device for a multi-level power converter.

[0172] As Figure 8As shown in the figure, the control device of the multi-stage power converter includes: a first processing module 810 and a second processing module 820.

[0173] The first processing module 810 is configured to obtain the capacitor voltages of each bus capacitor in the multi-stage power converter after the multi-stage power converter shuts down and before it restarts.

[0174] The second processing module 820 is configured to, when there is a first target capacitor voltage greater than a first voltage threshold corresponding to the first target capacitor voltage among the obtained capacitor voltages, control the discharge module to operate, or control the discharge module and a target power converter in a plurality of cascaded power converters to operate. The target power converter is configured to control the energy flow of the bus capacitor corresponding to the first target capacitor voltage to the discharge module to release the first target capacitor voltage.

[0175] According to the control device of the multi-stage power converter provided by the embodiments of the present application, after the multi-stage power converter shuts down and before it restarts, the capacitor voltages of each bus capacitor in the multi-stage power converter are obtained. When there is one or more capacitor voltages greater than a first voltage threshold corresponding to the one or more capacitor voltages among the obtained capacitor voltages, by controlling the discharge module to operate, or controlling the target power converter to operate, to control the energy flow of the bus capacitor corresponding to the one or more capacitor voltages to the discharge module. When controlling the discharge module to operate to release the first target capacitor voltage, it can be realized that the energy of the one or more capacitor voltages flows to the same discharge module through the target power converter for centralized discharge processing, so that the one or more capacitor voltages are less than their respective corresponding voltage thresholds, thereby reducing the energy residue of each bus capacitor after the multi-stage power converter shuts down and before it restarts, improving the stability of the bus voltage after restart, and thus improving the operation stability of the multi-stage power converter.

[0176] In some embodiments, the first processing module 810 may further be configured to:

[0177] Control the target power converter corresponding to the bus capacitor corresponding to the first target capacitor voltage to operate according to the first target capacitor voltage.

[0178] When the next bus capacitor cascaded with the target power converter is not connected in parallel with the discharge module and the capacitor voltage of the next bus capacitor is greater than a first voltage threshold corresponding to the capacitor voltage of the next bus capacitor, control the target power converter corresponding to the next bus capacitor to operate based on the capacitor voltage of the next bus capacitor.

[0179] When the next bus capacitor cascaded with the target power converter is in parallel with the discharge module, and when the capacitor voltage of the next bus capacitor is greater than the first voltage threshold corresponding to the capacitor voltage of the next bus capacitor, control the discharge module to operate.

[0180] In some embodiments, the second processing module 820 may further be configured to:

[0181] Based on the connection relationship between the bus capacitor corresponding to the first target capacitor voltage and the discharge module, determine the control object; the control object includes the discharge module, or the target power converter and the discharge module;

[0182] Control the control object to operate.

[0183] In some embodiments, the second processing module 820 may further be configured to:

[0184] When the bus capacitor corresponding to the first target capacitor voltage is in parallel with the discharge module, determine the control object as the discharge module;

[0185] When the condition that the bus capacitor corresponding to the first target capacitor voltage is in parallel with the discharge module is not satisfied, determine the control object as the target power converter and the discharge module.

[0186] In some embodiments, the second processing module 820 may further be configured to:

[0187] The discharge module includes a switch module and at least one discharge element connected in series; control the switch module to close.

[0188] In some embodiments, the second processing module 820 may further be configured to:

[0189] According to the first target capacitor voltage, control the duty cycle of the target power converter; the target power converter is determined based on the target flow direction, and the energy of the bus capacitor corresponding to the first target capacitor voltage flows along the target flow direction to the target power converter; the target flow direction is determined according to the topology of the multi-stage power converter and the installation position of the discharge module.

[0190] In some embodiments, the second processing module 820 may further be configured to:

[0191] Based on the difference between the first target capacitor voltage and the second voltage threshold corresponding to the first target capacitor voltage, determine the target duty cycle;

[0192] Based on the target duty cycle, control the target power converter to operate; the second voltage threshold corresponding to the first target capacitor voltage is less than the first voltage threshold corresponding to the first target capacitor voltage.

[0193] In some embodiments, the device may further include a third processing module for:

[0194] After controlling the target power converter to operate based on the target duty cycle, when the first target capacitor voltage is less than the first voltage threshold corresponding to the first target capacitor voltage, control the target power converter to stop operating.

[0195] In some embodiments, the device may further include a fourth processing module for:

[0196] When there is a first target capacitor voltage greater than the first voltage threshold corresponding to the first target capacitor voltage among the acquired capacitor voltages, after controlling the discharge module to operate, when all the capacitor voltages are less than the first voltage thresholds corresponding to the respective capacitor voltages, control the discharge module to stop operating.

[0197] In some embodiments, the device may further include a fifth processing module for:

[0198] Determine the first voltage threshold corresponding to each bus capacitor based on the connection position of each bus capacitor in the multi-stage power converter.

[0199] The control device of the multi-stage power converter in the embodiments of the present application may be an electronic device or a component in an electronic device, such as an integrated circuit or a chip. The electronic device may be a terminal or other devices other than a terminal. The embodiments of the present application do not make specific limitations.

[0200] The control device of the multi-stage power converter in the embodiments of the present application may be a device with an operating system. The operating system may be the Android operating system, the IOS operating system, or other possible operating systems. The embodiments of the present application do not make specific limitations.

[0201] The control device of the multi-stage power converter provided in the embodiments of the present application can implement Figures 1 to 7 each process implemented by the method embodiments, and for the sake of avoiding repetition, it will not be elaborated here.

[0202] In some embodiments, as Figure 9 shown, the embodiments of the present application further provide an electronic device 900, including a processor 901, a memory 902, and a computer program stored on the memory 902 and executable on the processor 901. When the program is executed by the processor 901, it implements each process of the control method embodiment of the above multi-stage power converter and can achieve the same technical effects. For the sake of avoiding repetition, it will not be elaborated here.

[0203] It should be noted that the electronic devices in the embodiments of the present application include the above-mentioned mobile electronic devices and non-mobile electronic devices.

[0204] An embodiment of the present application further provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements each process of the control method embodiment of the above multi-stage power converter and can achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0205] Wherein, the processor is the processor in the electronic device described in the above embodiment. The readable storage medium includes computer-readable storage media such as computer read-only memory ROM, random access memory RAM, magnetic disk or optical disc, etc.

[0206] An embodiment of the present application further provides a computer program product, including a computer program. When the computer program is executed by a processor, it implements the control method of the above multi-stage power converter.

[0207] Wherein, the processor is the processor in the electronic device described in the above embodiment. The readable storage medium includes computer-readable storage media such as computer read-only memory ROM, random access memory RAM, magnetic disk or optical disc, etc.

[0208] Another embodiment of the present application provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run programs or instructions to implement each process of the control method embodiment of the above multi-stage power converter and can achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0209] It should be understood that the chip mentioned in the embodiment of the present application may also be referred to as a system-on-chip, system chip, chip system or system-on-chip, etc.

[0210] It should be noted that in this article, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the methods and devices in the embodiments of the present application are not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in a reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0211] Through the description of the above embodiments, those skilled in the art can clearly understand that the above embodiment methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases, the former is a better implementation method. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the related technology, can be embodied in the form of a computer software product. The computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to enable a terminal (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in various embodiments of the present application.

[0212] The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all of them belong to the protection scope of the present application.

[0213] In the description of this specification, the description of reference terms such as "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0214] Although the embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle and purpose of the present application. The scope of the present application is defined by the claims and their equivalents.

Claims

1. A control method for a multi-level power converter, characterized in that, The multi-stage power converter includes a plurality of cascaded power converters. The multi-stage power converter is connected to positive and negative buses, and a plurality of bus capacitors are connected between the positive and negative buses. Among them, a first bus capacitor is arranged before the first end of the multi-stage power converter, a second bus capacitor is arranged after the second end of the multi-stage power converter, and a third bus capacitor is arranged between any two adjacent power converters; a discharge module is connected in parallel with any one of the bus capacitors; the method includes: After the multi-stage power converter is shut down and before it is restarted, obtain the capacitor voltages of the bus capacitors in the multi-stage power converter; When there is a first target capacitor voltage greater than a first voltage threshold corresponding to the first target capacitor voltage among the obtained capacitor voltages, control the discharge module to operate, or control the discharge module and a target power converter in the plurality of cascaded power converters to operate. The target power converter is used to control the energy of the bus capacitor corresponding to the first target capacitor voltage to flow to the discharge module to release the first target capacitor voltage.

2. The control method of the multi-stage power converter according to claim 1, wherein When there is a first target capacitor voltage greater than a first voltage threshold corresponding to the first target capacitor voltage among the obtained capacitor voltages, controlling the discharge module to operate, or controlling the discharge module and a target power converter in the plurality of cascaded power converters to operate, includes: Based on the connection relationship between the bus capacitor corresponding to the first target capacitor voltage and the discharge module, determine the control object; the control object includes the discharge module, or the target power converter and the discharge module; Control the control object to operate.

3. The control method of the multi-stage power converter according to claim 2, characterized in that The determining the control object based on the connection relationship between the bus capacitor corresponding to the first target capacitor voltage and the discharge module includes: When the bus capacitor corresponding to the first target capacitor voltage is connected in parallel with the discharge module, determine the control object as the discharge module; When the condition that the bus capacitor corresponding to the first target capacitor voltage is connected in parallel with the discharge module is not satisfied, determine the control object as the target power converter and the discharge module.

4. The control method of the multi-stage power converter according to claim 1, wherein The discharge module includes a switch module and at least one discharge element connected in series; controlling the discharge module to operate includes: Control the switch module to close.

5. The control method of the multi-stage power converter according to any one of claims 1-4, characterized in that, Controlling the target power converter in the plurality of cascaded power converters to operate includes: According to the first target capacitor voltage, control the duty cycle of the target power converter; the target power converter is determined based on the target flow direction, and the energy of the bus capacitor corresponding to the first target capacitor voltage flows to the target power converter along the target flow direction; the target flow direction is determined according to the topology of the multi-stage power converter and the installation position of the discharge module.

6. The control method of the multi-stage power converter according to claim 5, characterized in that, The controlling the duty cycle of the target power converter according to the first target capacitor voltage includes: Based on the difference between the first target capacitor voltage and a second voltage threshold corresponding to the first target capacitor voltage, determine the target duty cycle; Based on the target duty cycle, control the operation of the target power converter; the second voltage threshold corresponding to the first target capacitor voltage is less than the first voltage threshold corresponding to the first target capacitor voltage.

7. The control method of the multi-stage power converter according to claim 6, characterized in that, After controlling the operation of the target power converter based on the target duty cycle, the method further includes: When the first target capacitor voltage is less than the first voltage threshold corresponding to the first target capacitor voltage, control the target power converter to stop operating.

8. The control method of the multi-stage power converter according to any one of claims 1-4, characterized in that, The control of the operation of the target power converter in the discharge module and the plurality of cascaded power converters includes: Control the target power converter corresponding to the bus capacitor corresponding to the first target capacitor voltage to operate according to the first target capacitor voltage. When the next bus capacitor cascaded with the target power converter is not connected in parallel with the discharge module and the capacitor voltage of the next bus capacitor is greater than the first voltage threshold corresponding to the capacitor voltage of the next bus capacitor, control the target power converter corresponding to the next bus capacitor to operate based on the capacitor voltage of the next bus capacitor. When the next bus capacitor cascaded with the target power converter is connected in parallel with the discharge module and the capacitor voltage of the next bus capacitor is greater than the first voltage threshold corresponding to the capacitor voltage of the next bus capacitor, control the discharge module to operate.

9. The control method of the multi-stage power converter according to any one of claims 1-4, characterized in that, After controlling the discharge module to operate when there is a first target capacitor voltage greater than the first voltage threshold corresponding to the first target capacitor voltage among the obtained capacitor voltages, the method further includes: When all the capacitor voltages are less than the first voltage thresholds corresponding to the respective capacitor voltages, control the discharge module to stop operating.

10. The control method of the multi-stage power converter according to any one of claims 1-4, characterized in that, The first voltage threshold corresponding to each bus capacitor is determined based on the connection position of each bus capacitor in the multi-stage power converter.

11. A multistage power converter system, characterized in that, Includes: A plurality of cascaded power converters, and the plurality of cascaded power converters are connected to the positive and negative buses. A plurality of bus capacitors, and the plurality of bus capacitors are connected between the positive and negative buses. Among them, the first bus capacitor is arranged before the first end of the multi-stage power converter, the second bus capacitor is arranged after the second end of the multi-stage power converter, and the third bus capacitor is arranged between any adjacent power converters. A discharge module, and the discharge module is connected in parallel with any one of the bus capacitors. The multi-stage power converter system operates based on the control method of the multi-stage power converter according to any one of claims 1-10.

12. The multi-stage power converter system according to claim 11, characterized in that, The discharge module includes: A switch module; At least one discharge element, and the at least one discharge element is connected in series with the switch module.

13. The multi-level power converter system according to claim 11, wherein, The power converter includes: A subtractor, and two input terminals of the subtractor are respectively used to receive the first target capacitor voltage and the second voltage threshold corresponding to the first target capacitor voltage. A regulator, the input terminal of the regulator is connected to the output terminal of the subtractor, and the output terminal of the regulator is used to output the target duty cycle.

14. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the control method of the multi-level power converter according to any one of claims 1-10.

15. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the control method of the multi-level power converter according to any one of claims 1-10.

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