Control method, device and equipment of device series type converter, medium and product

Abstract

The invention discloses a control method, device, equipment, medium and product of a device series converter, and relates to the technical field of power electronics, when two bridge arms of the device series converter are switched, before a main power device on a target switching bridge arm is switched on, auxiliary tubes corresponding to all main power devices on the bridge arms are controlled to be switched on, and the main power device on the target switching bridge arm is switched on. Redundant energy on the clamping capacitor is recycled by using the voltage difference between the voltage of the clamping capacitor and the voltage of the bus and the conducted auxiliary tube, so that abnormal rise of the voltage of the clamping capacitor in the commutation process is avoided; meanwhile, the driving delay of the main power device is dynamically adjusted according to the voltage of the clamping capacitor, so that the main power device is ensured to synchronously switch on and off, and charging introduced by asynchronous actions of the main power device is avoided, thereby ensuring that the clamping function of the clamping capacitor is effectively realized; the voltage sharing between the main power devices connected in series in the device series converter is ensured, and the safe and reliable operation of the whole device series converter is ensured.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and particularly to a control method, device, equipment, medium and product for a device series-connected converter. Background Art

[0002] In application scenarios such as large-capacity data centers, super charging stations, flexible DC power transmission, and defense equipment, medium- and high-voltage power electronic equipment is required to achieve power conversion. Taking medium-voltage power electronic equipment as an example, its voltage level is usually 1 kV - 35 kV. Currently, the breakdown voltages of common commercial Insulated-Gate Bipolar Transistors (IGBTs) and Silicon-Carbide Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs, simply referred to as SiC MOSFETs) are 6.5 kV and 1.7 kV respectively. Therefore, a single semiconductor power device cannot directly withstand medium- and high-voltages of 10 kV and above. To match the breakdown voltage level of the device and the voltage level of the equipment, there are currently two main solutions: one is to improve the performance of the power device and increase its breakdown voltage level; the other is to apply a multi-level conversion technology or device series connection by changing the topology to apply low-breakdown-voltage devices to medium- and high-voltage scenarios.

[0003] Device series connection means that multiple power devices (including MOSFETs, IGBTs, etc.) are connected in series and used as a whole device series connection module in a converter. Compared with the multi-level scheme, it has the advantages of simple circuit and fewer device numbers. The key problem to be solved in device series connection is how to maintain the voltage balance of each device, because once a device is over-voltage, it will be quickly broken down and damaged.

[0004] In the prior art, an active clamping circuit (Active Clamping Module, ACM) is connected in parallel at both ends of each series-connected power device to help achieve the voltage balance of the series-connected devices. The active clamping circuit includes a series-connected auxiliary power device and a clamping capacitor. Maintaining the voltage balance of the clamping capacitor can achieve the voltage equalization of the series-connected power devices. Therefore, the active clamping circuit converts the problem of how to ensure that the power device does not over-voltage into the problem of how to ensure that each clamping capacitor does not over-voltage. After each power device is equipped with an active clamping circuit, if the voltage of the power device exceeds the voltage of the clamping capacitor, the voltage of the power device will be automatically clamped by the clamping capacitor. Maintaining the voltage balance of the clamping capacitor can achieve the voltage balance of each series-connected power device. However, in actual operation, the switching moments of the power devices are not synchronized, and the commutation during the turn-on process will cause the clamping capacitor to charge, making the active clamping circuit lose its clamping function, resulting in uneven voltages or even damage to the series-connected power devices. Summary of the Invention

[0005] The object of the present invention is to provide a control method, device, equipment, medium and product for a device series-connected converter, which can avoid the abnormal increase in the voltage of the clamping capacitor and the charging introduced by the asynchronous operation of the main power devices during the commutation process, ensure the effective realization of its clamping function, thereby ensuring the voltage sharing between the series-connected main power devices in the device series-connected converter, and ensuring the safe and reliable operation of the entire device series-connected converter.

[0006] To solve the above technical problems, the present invention provides a control method for a device series-connected converter. The device series-connected converter includes at least one half-bridge circuit. The half-bridge circuit includes a first bridge arm and / or a second bridge arm connected in series. Both the first bridge arm and the second bridge arm include a plurality of main power devices connected in series. An active clamping circuit is connected in parallel at both ends of each main power device. The active clamping circuit includes an auxiliary transistor and a clamping capacitor connected in series. The main power devices of the first bridge arm and the main power devices of the second bridge arm conduct alternately. The control method for the device series-connected converter includes:

[0007] Taking the voltages of all the clamping capacitors in the same bridge arm to be consistent as the goal, adjusting the drive delays of the corresponding main power devices on the corresponding bridge arm respectively based on the voltages of the respective clamping capacitors in the same bridge arm, so as to subsequently control the actions of each main power device based on the adjusted drive delays;

[0008] When the device series-connected converter switches from the state where the first bridge arm conducts to the state where the second bridge arm conducts, before the main power devices of the second bridge arm conduct, control the auxiliary transistors corresponding to all the main power devices of the second bridge arm to conduct;

[0009] When the on-time of the auxiliary transistor reaches the total preset time, control the auxiliary transistors corresponding to all the main power devices of the second bridge arm to turn off;

[0010] After the auxiliary transistors corresponding to all the main power devices of the second bridge arm are turned off, control the conduction and turn-off of each main power device in the second bridge arm respectively based on the adjusted drive delays to achieve the balance of the clamping capacitor voltages and the voltage sharing of the main power devices.

[0011] Optionally, controlling the auxiliary transistors corresponding to all the main power devices of the second bridge arm to conduct includes:

[0012] Determining the starting moment of the dead zone when the device series-connected converter switches from the state where the first bridge arm conducts to the state where the second bridge arm conducts;

[0013] Taking the starting moment of the dead zone as a reference, control the auxiliary tubes corresponding to all the main power devices of the second bridge arm to conduct in advance by a first preset duration; the first preset duration is less than the total preset duration.

[0014] Optionally, take the first bridge arm or the second bridge arm as the target bridge arm for drive delay adjustment, and take the voltages of all the clamping capacitors in the same bridge arm to be consistent as the target, and adjust the drive delays of the corresponding main power devices on the corresponding bridge arm respectively based on the voltages of the respective clamping capacitors in the same bridge arm, including:

[0015] Obtain the current voltages of the respective clamping capacitors in the target bridge arm every several switching cycles;

[0016] For any one of the clamping capacitors in the target bridge arm, subtract the current voltage of the clamping capacitor from the reference voltage to obtain a voltage difference; wherein, the reference voltage is the target voltage for the voltages of the clamping capacitors to be consistent;

[0017] Input the calculated voltage difference into a compensator to obtain the drive delay of the main power device corresponding to the voltage of the clamping capacitor, so as to control the actions of the respective main power devices based on the obtained drive delay; the compensator includes at least one integral link.

[0018] Optionally, the process of determining the reference voltage includes:

[0019] Arbitrarily select one of the current voltages of all the clamping capacitors in the target bridge arm and determine it as the reference voltage for delay control;

[0020] Or,

[0021] Determine the average value of the current voltages of all the clamping capacitors in the target bridge arm as the reference voltage for delay control;

[0022] Or,

[0023] Determine the weighted average of the voltages of any one or more clamping capacitors in the target bridge arm as the reference voltage.

[0024] Optionally, after inputting the calculated voltage difference into a compensator to obtain the drive delay of the main power device corresponding to the voltage of the clamping capacitor, further include:

[0025] Update the delay register every several switching cycles based on the obtained drive delay of the main power device.

[0026] Optionally, when the output result of the delay register is positive, the drive delay of the main power device is the delay time after the turn-off moment of the main power device and / or the leading time at the turn-on moment of the main power device;

[0027] When the output result of the delay register is negative, the driving delay of the main power device is the leading time at the turn-off moment of the main power device and / or the delaying time at the turn-on moment of the main power device.

[0028] To solve the above technical problems, the present invention further provides a control device for a device series-connected converter. The device series-connected converter includes at least one half-bridge circuit. The half-bridge circuit includes a first bridge arm and a second bridge arm connected in series. The first bridge arm and / or the second bridge arm each includes a plurality of main power devices connected in series. An active clamping circuit is connected in parallel at both ends of each of the main power devices. The active clamping circuit includes an auxiliary tube and a clamping capacitor connected in series. The main power devices of the first bridge arm and the main power devices of the second bridge arm conduct alternately; the control device for the device series-connected converter includes:

[0029] A driving adjustment unit, configured to target that the voltages of all the clamping capacitors in the same bridge arm are consistent, and respectively adjust the driving delays of the corresponding main power devices on the corresponding bridge arm based on the voltages of the respective clamping capacitors in the same bridge arm, so as to subsequently control the actions of the respective main power devices based on the adjusted driving delays;

[0030] A differential pressure discharge unit, configured to, when the device series-connected converter switches from a state where the first bridge arm conducts to a state where the second bridge arm conducts, before the main power devices of the second bridge arm conduct, control the auxiliary tubes corresponding to all the main power devices of the second bridge arm to conduct; when the on-time of the auxiliary tubes reaches the total preset time, control the auxiliary tubes corresponding to all the main power devices of the second bridge arm to turn off;

[0031] A main power device driving unit, configured to control the first bridge arm and the second bridge arm to conduct alternately; after the auxiliary tubes corresponding to all the main power devices of the second bridge arm turn off, respectively control the conduction and turn-off of the respective main power devices in the second bridge arm based on the adjusted driving delays, so as to achieve the balance of the clamping capacitor voltages and the voltage equalization of the main power devices.

[0032] To solve the above technical problems, the present invention further provides an electronic device, including:

[0033] A memory, configured to store a computer program;

[0034] A processor, configured to implement the steps of the control method for the device series-connected converter as described above.

[0035] To solve the above technical problems, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the control method of the device series-connected converter as described above are implemented.

[0036] To solve the above technical problems, the present invention also provides a computer program product, including a computer program / instructions. When the computer program / instructions are executed by a processor, the steps of the control method of the device series-connected converter as described above are implemented.

[0037] The present invention provides a control method for a device series-connected converter. When switching between two bridge arms of the device series-connected converter, before the main power device on the target switching bridge arm is turned on, control the auxiliary tubes corresponding to all the main power devices on the bridge arm to be turned on, and use the voltage difference between the clamped capacitor voltage and the bus voltage and the turned-on auxiliary tubes to recover the excess energy on the clamped capacitor, thereby avoiding the abnormal increase of the clamped capacitor voltage during the commutation process; at the same time, dynamically adjust the driving delay of the main power device according to the voltage of the clamped capacitor to ensure the consistency of the voltages of each clamped capacitor when the main power device operates, and avoid the charging caused by the asynchronous operation of the main power devices, so as to ensure the effective implementation of the clamping function of the clamped capacitor, ensure the voltage sharing between the series-connected main power devices in the device series-connected converter, and ensure the safe and reliable operation of the entire device series-connected converter.

[0038] The present invention also provides a control device, an electronic device, and a computer-readable storage medium for a device series-connected converter, which have the same beneficial effects as the control method of the above device series-connected converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the prior art and the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0040] Figure 1 It is a schematic flow chart of a control method for a device series-connected converter provided by the present invention;

[0041] Figure 2 It is a schematic flow chart of another control method for a device series-connected converter provided by the present invention;

[0042] Figure 3 It is a schematic structural diagram of a device series module provided by the present invention;

[0043] Figure 4Schematic structural diagram of a device series-connected converter when both bridge arms adopt device series-connected modules provided by the present invention;

[0044] Figure 5 Schematic equivalent circuit diagram of a device series-connected converter during differential pressure discharge provided by the present invention;

[0045] Figure 6 Schematic signal timing diagram of a device series-connected converter during differential pressure discharge provided by the present invention;

[0046] Figure 7 Schematic structural diagram of a device series-connected converter when only one bridge arm adopts a device series-connected module provided by the present invention;

[0047] Figure 8 Schematic signal timing diagram of a device series-connected converter during differential pressure discharge when only one bridge arm adopts a device series-connected module provided by the present invention;

[0048] Figure 9 Schematic diagram of switch delay control of a device series-connected converter provided by the present invention;

[0049] Figure 10 Control block diagram of adjusting switch delay of a device series-connected converter provided by the present invention;

[0050] Figure 11 Schematic waveform diagram of adjusting switch delay of a device series-connected converter provided by the present invention;

[0051] Figure 12 Schematic diagram of the driving signal delay adjustment method of a main power device provided by the present invention;

[0052] Figure 13 Schematic signal waveform diagram of the switch delay adjustment process of a device series-connected converter provided by the present invention;

[0053] Figure 14 Schematic structural diagram of an electronic device provided by the present invention. Detailed implementation manners

[0054] The core of the present invention is to provide a control method, device, equipment, medium and product for a device series-connected converter, which can avoid the abnormal increase in the voltage of the clamping capacitor during the commutation process and the charging caused by the asynchronous operation of the main power devices, ensure the effective realization of its clamping function, thereby ensuring the voltage sharing between the series-connected main power devices in the device series-connected converter, and ensuring the safe and reliable operation of the entire device series-connected converter.

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0056] Please refer to Figure 1 , Figure 1 which is a schematic flowchart of a control method for a device series-connected converter provided by the present invention; please refer to Figure 2 , Figure 2 which is a schematic flowchart of another control method for a device series-connected converter provided by the present invention; to solve the above technical problems, the present invention provides a control method for a device series-connected converter. The device series-connected converter includes at least one half-bridge circuit. The half-bridge circuit includes a first bridge arm and / or a second bridge arm connected in series. Both the first bridge arm and the second bridge arm include a plurality of main power devices connected in series. An active clamping circuit is connected in parallel at both ends of each main power device. The active clamping circuit includes an auxiliary tube and a clamping capacitor connected in series. The main power devices of the first bridge arm and the main power devices of the second bridge arm conduct alternately; the control method for the device series-connected converter includes:

[0057] S11: Aiming at making the voltages of all the clamping capacitors in the same bridge arm consistent, adjust the driving delays of the corresponding main power devices on the corresponding bridge arm respectively based on the voltages of the clamping capacitors in the same bridge arm, so as to control the actions of each main power device based on the adjusted driving delays subsequently.

[0058] Considering that in actual operation, the clamping capacitor will not only be charged due to the commutation process, but also be charged due to the asynchronous switching between the main power devices. When the driving signal of a certain main power device in the same bridge arm is asynchronous with the driving signals of other main power devices and the current flowing through this bridge arm is a positive current, the early turn-on of this main power device will cause the clamping capacitors corresponding to other main power devices to be charged; the early turn-off of this main power device will cause the clamping capacitor corresponding to itself to be charged, resulting in different charging amounts of different clamping capacitors on the same bridge arm and causing a difference in the clamping capacitor voltage. Therefore, the present invention also proposes that the driving signal delay of the main power device needs to be adjusted based on the clamping capacitor voltage.

[0059] It is not difficult to understand that the asynchronous switching of the main power devices will cause some clamping capacitors to be charged, resulting in voltage inconsistency among the clamping capacitors and affecting the voltage sharing effect. Therefore, adjusting the driving delay of each main power device is ultimately to achieve the same voltage of each clamping capacitor. Therefore, it is necessary to obtain the voltage of each clamping capacitor, and accordingly adjust the driving delay of each main power device. By adjusting the driving delay, the switching actions of the main power devices are adjusted to a consistent state, so as to achieve the same voltage of all clamping capacitors. The driving delay of the main power device refers to the delay of the driving signal applied to the control terminal of the main power device. Adjusting the driving delay specifically includes adjusting the conduction time and / or the turn-off time of the driving signal.

[0060] S12: When the device series converter switches from the state where the first bridge arm conducts to the state where the second bridge arm conducts, before the main power devices of the second bridge arm conduct, control the auxiliary tubes corresponding to all the main power devices of the second bridge arm to conduct.

[0061] Considering that in the device series converter, the transformation of the power supply is realized by setting several half-bridge topologies, etc. The half-bridge circuit topology includes two bridge arms, and main power devices are respectively arranged on the two bridge arms. When the device series converter works, the main power devices on the two bridge arms conduct alternately. When the main power device on the first bridge arm conducts, the main power device on the second bridge arm turns off. When the main power device on the second bridge arm conducts, the main power device on the first bridge arm turns off; the transformation and control of the power supply are realized by using the alternately conducting main power devices. At this time, the process of the device series converter switching from the state where one bridge arm conducts to the state where the other bridge arm conducts is called commutation. In order to avoid the direct connection between the upper bridge arm and the lower bridge arm, when switching the conduction states of the two bridge arms, a dead zone of alternate conduction is set between the turn-off of the first bridge arm and the conduction of the second bridge arm. Taking the device series converter switching from the state where the upper bridge arm conducts to the state where the lower bridge arm conducts as an example, the circuit current when the upper bridge arm conducts needs to experience a period of time to commutate from one bridge arm to the other bridge arm. During this period, this circuit current will pass through the parasitic diodes of the auxiliary tubes corresponding to each main power device in the upper bridge arm, resulting in the charging of the clamping capacitors and the increase of the voltages of all clamping capacitors. For this reason, the present invention recovers the energy of all clamping capacitors by setting differential pressure discharge and using the principle of energy transfer from the high-voltage capacitor to the low-voltage capacitor, and reduces the voltages of all clamping capacitors without discrimination.

[0062] It is not difficult to understand that both the first bridge arm and the second bridge arm are implemented by device series modules, each of which includes several series-connected main power devices to achieve voltage division. Therefore, in order to achieve voltage sharing of each series-connected main power device, for each main power device, an active clamping circuit is provided in parallel with it. Please refer to Figure 3 , Figure 3Schematic diagram of the structure of a device series module provided by the present invention; the active clamping circuit includes an auxiliary transistor and a clamping capacitor connected in series, and the voltages across the main power devices are the same as the voltages across the corresponding parallel clamping capacitors. At the same time, the first arm and the second arm are connected in series, and the series circuit serves as a half-bridge circuit and is connected in parallel across the power supply, thereby realizing the conversion of the output voltage of the power supply. Theoretically, when the device series converter is operating, the output voltage of the power supply is evenly divided by the clamping capacitors corresponding to the conducting main power devices. During normal operation, taking a DC power supply as an example, if there are N conducting main power devices in the converter in a certain state, then v c1 +v c2 + +v cN =V dc ; However, during the commutation process, since the current takes a certain time to commutate from one arm to the other arm, during this period, the clamping capacitors are charged, and the voltages of all the clamping capacitors increase, resulting in v c1 +v c2 + +v cN >V dc . Therefore, before the main power device of this arm is controlled to conduct next time, all the auxiliary transistors corresponding to this arm can be controlled to conduct, so that the clamping capacitors are directly connected to the power supply to form a loop. At the same time, since v c1 +v c2 + +v cN >V dc , this voltage difference will cause the clamping capacitors to discharge to the power supply, thereby realizing the recovery of the excess energy on the clamping capacitors.

[0063] It can be understood that, please refer to Figure 4 , Figure 4 Schematic diagram of the structure of a device series converter when both arms adopt device series modules provided by the present invention; the two arms in the device series converter are connected to a DC bus V dc , and the midpoints of the two arms lead out output terminals, and the output terminals can be connected to different types of circuits to realize an inverter or a DC / DC (Direct Current / Direct Current) converter based on the two arms adopting device series modules. Please refer to Figure 5 , Figure 5 Schematic diagram of the equivalent circuit when the device series converter discharges due to voltage difference provided by the present invention; Figure 5 As shown, it is the topological structure of a boost circuit (boost converter) realized based on the two arms adopting device series modules. V out is also DC. The upper arm is provided with S1' to S N’The clamped capacitor voltages corresponding to these N series-connected main power devices are respectively v c1 ’ to v cN ’. S1 to S are set on the upper bridge arm N The clamped capacitor voltages corresponding to these N series-connected main power devices are respectively v c1 ’ to v cN . For any device series module, before the corresponding main power device is turned on, all the auxiliary transistors in the device series module are turned on, and all the clamped capacitors in the device series module are inserted into the circuit. As long as the sum of all the clamped capacitor voltages v c1 + v c2 + + v cN > V dc , the redundant energy on the clamped capacitor can be recovered by using the voltage difference, and i is the current for the clamped capacitor to discharge.

[0064] S13: When the on-time of the auxiliary transistor reaches the total preset time, control the auxiliary transistors corresponding to all the main power devices of the second bridge arm to turn off.

[0065] It is not difficult to understand that the voltage difference discharge only needs to recover the abnormal charge amount on the clamped capacitor due to commutation. Therefore, when the voltage difference discharge reaches a certain extent and reaches the preset condition, the auxiliary transistor can be controlled to turn off to stop the voltage difference discharge. The specific type and implementation manner of the preset condition are not particularly limited in this application. The recovery progress of the redundant energy on the clamped capacitor can be judged according to the specific situation of the sum of the capacitor voltages of all the clamped capacitors, or a fixed discharge time can be directly set, and the voltage difference discharge stops after lasting for the preset time.

[0066] It can be understood that the differential-pressure discharge will only occur when there is a pressure difference between the sum of the capacitor voltages of all the clamping capacitors and the bus voltage. Therefore, the on-time of the auxiliary tube can be determined in advance according to the duration of the differential-pressure discharge. When the on-time of the auxiliary tube is relatively long, the difference between the sum of the clamping capacitor voltages and the bus voltage will also become very small, even approaching 0. It is also possible to control the turn-off of the auxiliary tube by detecting in real time whether the differential-pressure discharge ends. The on-time of the auxiliary tube and the specific turn-off moment can be set and adjusted according to the actual application situation. In order to realize the normal commutation of the converter, it is still necessary to turn off the auxiliary tube to actively control the end of the differential-pressure discharge. The bus voltage refers to the power supply voltage connected to the device series converter. The specific type of the power supply and the voltage magnitude are not particularly limited in this application. Considering that the difference between the sum of the clamping capacitor voltages and the bus voltage when the auxiliary tube is turned off may not be completely reduced to 0, the auxiliary tube can be controlled to turn off to end the discharge when the voltage difference between the sum of the capacitor voltages of all the clamping capacitors and the bus voltage of the device series converter is less than a preset value. At this time, although there is still a certain pressure difference between the sum of the clamping capacitor voltages and the bus voltage, this pressure difference is relatively small and will not overly affect the clamping effect of the clamping capacitor. The specific value of the total preset duration can be set according to the actual situation and is not particularly limited in this application.

[0067] S14: After all the auxiliary tubes corresponding to the main power devices in the second bridge arm are turned off, control the conduction and turn-off of each main power device in the second bridge arm based on the adjusted driving delay to achieve the balance of the clamping capacitor voltages and the equal voltage of the main power devices.

[0068] It can be understood that after discharging the clamping capacitor, the conduction of the main power devices in the second bridge arm can be continued to control normally, so as to realize the complete commutation of the converter. At this time, when controlling the conduction of the main power devices on the second bridge arm, it is necessary to generate the driving signals of the main power devices on the second bridge arm based on the previously adjusted driving delay of the main power devices, so as to avoid the unsynchronized conduction of the main power devices on the second bridge arm, and simultaneously avoid the abnormal charging of the clamping capacitor from the two aspects of commutation and switch unsynchronization, and ensure its equal voltage effect. Generally, the bridge arm connected to the positive pole of the power supply is defined as the upper bridge arm, and the bridge arm connected to the negative pole of the power supply is defined as the lower bridge arm. The first bridge arm can be the upper bridge arm or the lower bridge arm. When the first bridge arm is the upper bridge arm, the second bridge arm is the lower bridge arm; when the first bridge arm is the lower bridge arm, the second bridge arm is the upper bridge arm. The first bridge arm and the second bridge arm are not particularly limited in this application. The adjustment of the driving delay can not only be applied when controlling the conduction of the main power devices in the second bridge arm, but also can be applied when controlling the turn-off of the main power devices in the second bridge arm, controlling the conduction or turn-off of the main power devices in the first bridge arm. As long as it is the action of the main power device, it needs to be realized based on the adjusted driving delay.

[0069] It should be noted that since commutation occurs in each switching cycle of the converter, the optimal embodiment of the discharge of the clamping capacitor is to perform it once in each switching cycle. It can also be adjusted and set according to the specific charging situation of the clamping capacitor. This application does not make special limitations here. A switching cycle of the converter is the time required to complete an on-off-on cycle. Taking the initial working state of the converter with the upper arm conducting as an example, a switching cycle is the duration of the entire process from the moment when the upper arm starts to conduct, passing through the upper arm turning off, the lower arm conducting, the lower arm turning off in sequence, and then to the moment when the upper arm starts to conduct again.

[0070] Considering that when the converter commutes, the clamping capacitors corresponding to all the main power devices on the two arms will be charged. Therefore, when discharging the clamping capacitors, all the auxiliary tubes need to be turned on, and all the clamping capacitors need to be inserted into the circuit to release the charging power introduced by the commutation process for each clamping capacitor. On the other hand, since the main power device itself has parasitic capacitance, taking N main power devices connected in series as an example, if one clamping capacitor is not inserted, then it is N - 1 clamping capacitors and the parasitic capacitance of 1 main power device discharging together. The capacitance value of the parasitic capacitance is much smaller than that of the clamping capacitor, and the voltage drop caused by the discharge will mainly become the voltage drop of the parasitic capacitance, resulting in a significant reduction in the discharge amount of the clamping capacitor. Therefore, when discharging the clamping capacitors, all the clamping capacitors need to be inserted into the circuit to ensure the discharge of each clamping capacitor and sufficient discharge amount, and to ensure that all clamping capacitors will not have overvoltage. By using the control method provided by the present invention, there will also be no situation where the voltage is less than the sum of the voltages of all clamping capacitors and greater than the bus voltage of the power supply, thereby ensuring that the clamping capacitors can effectively achieve the clamping and voltage equalization of each main power device.

[0071] It should be further noted that after executing step S11, the voltage equalization of the clamping capacitors on the same arm can be achieved by adjusting the driving delay of the main power device. However, at this time, the energy accumulated in the clamping capacitors has not been released in time, and the situation where the voltages of all clamping capacitors are too high and the protection function (clamping effect) is lost may occur. Therefore, after adjusting the driving delay, it is also necessary to combine the differential pressure discharge in the subsequent steps to release the energy accumulated in the clamping capacitors due to the commutation process back to the bus in time, so that the voltages of all clamping capacitors are balanced at the average bus voltage.

[0072] It should be noted that the specific types and implementation methods of the main power devices, auxiliary transistors, and clamping capacitors in the device series-connected converter are not particularly limited in this application. There are also various choices for the number of main power devices provided on each bridge arm, which are not particularly limited in this application. The main power device is generally implemented by using MOS transistors or IGBTs with parasitic capacitors and parasitic diodes. The auxiliary transistor can be implemented by using switching devices such as MOS transistors or IGBTs with parasitic diodes. Among them, the conduction of the first bridge arm means that all the main power devices on the first bridge arm are conducting, and the turn-off of the first bridge arm means that all the main power devices on the first bridge arm are turned off. The two bridge arms in the half-bridge circuit can both be implemented by using series-connected main power devices, or only one bridge arm can be implemented by using series-connected main power devices, and the other bridge arm can be implemented by using a single power device or a diode. However, as long as there is one bridge arm in the half-bridge circuit that uses series-connected main power devices, the control method provided in this application can be used to ensure voltage sharing between the series-connected main power devices. Obviously, when one of the bridge arms is a diode, there is no so-called dead zone. At this time, for the selection of the time for differential voltage discharge, it only needs to be staggered from the conduction time of the corresponding main power device.

[0073] The present invention utilizes differential voltage discharge to recover the redundant energy in the clamping capacitors. The differential voltage discharge recovers the energy of all the clamping capacitors, reduces the voltages of each clamping capacitor without discrimination, thereby ensuring that each clamping capacitor does not overvoltage. Then, by using the clamping effect of the clamping capacitors on the main power devices, during the high-speed switching operation, it is ensured that the main power devices do not overvoltage, effectively realizing the accuracy and reliability of the operation of the device series module. It can be applied to the circuit topologies in which multiple device series modules are connected in series, and is not limited to the structure of the half-bridge circuit.

[0074] As a specific embodiment, there is commutation in the circuit of the device series-connected converter. During the commutation process, the current continuously charges the clamping capacitors, and the voltages of the clamping capacitors of each series device increase together. It is necessary to utilize differential voltage discharge to recover the redundant energy in the clamping capacitors. Taking the main power device on the upper bridge arm of the converter as an example, please refer to Figure 6 , Figure 6 which is a signal timing diagram of differential voltage discharge of a device series-connected converter provided by the present invention; where g is the driving signal of the main power device on the upper bridge arm, g' is the driving signal of the main power device on the lower bridge arm, and ga is the driving signal of the auxiliary transistor corresponding to g. In order to avoid the direct conduction of the main power device and the auxiliary transistor, it is selected to discharge the clamping capacitor before the main power device conducts. Therefore, ga is located in the dead zone before the corresponding main power device is turned on, and the falling edge of ga is earlier than the rising edge of g. As shown in the figure, the dead zone before the upper bridge arm is turned on is dead zone 1, t dis the dead time of dead zone 1. The dead zone before the lower arm is turned on is dead zone 2. Therefore, ga is located in dead zone 1. To ensure the discharge duration of the clamping capacitor, ga can exist ahead of dead zone 1, that is, ahead by Δt. Δt can be a time from 0 to several μs to help the auxiliary tube achieve zero-voltage turn-on; the conduction time of ga within dead zone 1 is t a , the total voltage difference discharge time, that is, the total preset duration t dis =Δt + t a , Δt and t a can both be determined by means such as experience and need to be selected according to the application scenario.

[0075] As a specific embodiment, please refer to Figure 7 , Figure 7 is a schematic structural diagram of a device series-connected converter when only one arm adopts a device series module provided by the present invention. Vin is the input voltage, Vdc is the DC voltage output by the conversion. The device series-connected converter includes a capacitor Cin connected in parallel between two input terminals, a capacitor Co connected in parallel between two output terminals, a freewheeling inductor L, an upper arm and a lower arm; please refer to Figure 8 , Figure 8 is a schematic signal timing diagram of voltage difference discharge of a device series-connected converter when only one arm adopts a device series module provided by the present invention; the upper arm of the device series-connected converter is implemented by a diode, and the lower arm is implemented by a device series module. At this time, g is the drive signal of the main power device of the lower arm, and ga is the drive signal of the auxiliary tube corresponding to g. The falling edge of ga is earlier than the rising edge of g, and the high-level interval of ga is staggered from the high-level interval of g, that is, the conduction interval of the main power device.

[0076] The present invention provides a control method for a device series-connected converter. When the device series-connected converter switches between two arms, before the main power device on the target switching arm is turned on, control the auxiliary tubes corresponding to all the main power devices on the arm to be turned on, and use the voltage difference between the clamping capacitor voltage and the bus voltage and the turned-on auxiliary tubes to recover the excess energy on the clamping capacitor, thereby avoiding the abnormal increase of the clamping capacitor voltage during the commutation process; at the same time, dynamically adjust the drive delay of the main power device according to the voltage of the clamping capacitor to ensure the consistency of the clamping capacitor voltages when the main power device acts, and avoid the charging introduced by the asynchronous operation of the main power devices, thereby ensuring the effective realization of the clamping function of the clamping capacitor, ensuring the voltage sharing between the series-connected main power devices in the device series-connected converter, and improving the safety and reliability of the entire device series-connected converter.

[0077] Based on the above embodiments:

[0078] As an optional embodiment, controlling the auxiliary tubes corresponding to all the main power devices of the second arm to be turned on includes:

[0079] Determine the dead-time start moment when the device series converter switches from the conduction state of the first bridge arm to the conduction state of the second bridge arm;

[0080] Taking the dead-time start moment as a reference, control the auxiliary tubes corresponding to all the main power devices of the second bridge arm to conduct in advance for a first preset duration; the first preset duration is less than the total preset duration.

[0081] To avoid a short circuit in the circuit when the main power devices connected in parallel and the corresponding auxiliary tubes conduct simultaneously, the auxiliary tubes must complete conduction before the corresponding main power devices. Generally, the dead-time duration set for the alternate conduction of the bridge arms during converter commutation is relatively small. If the auxiliary tubes only conduct within the dead-time between the turn-off of the first bridge arm and the turn-on of the second bridge arm, the discharge time limitation of the clamping capacitor is relatively large. Therefore, to provide sufficient discharge duration to support the discharge of the clamping capacitor, the start moment of the conduction of the auxiliary tubes can also be advanced by a certain period, that is, the conduction of the auxiliary tubes is not limited to only within the dead-time. At this time, it is necessary to first determine the dead-time start moment when the device series converter switches from the conduction state of the first bridge arm to the conduction state of the second bridge arm, that is, the moment when the first bridge arm turns off. Generally, the converter will set a fixed alternate conduction dead-time according to actual application requirements. Therefore, based on this dead-time start moment, control the auxiliary tubes to conduct Δt in advance, so as to extend the conduction duration of the auxiliary tubes. The specific method for the dead-time start moment and so on are not particularly limited in this application. There are various choices for the specific value of the first preset duration, which are not particularly limited in this application. The first preset duration cannot be greater than the conduction duration of the first bridge arm, and different application scenarios can be adapted by adjusting the first preset duration to achieve different discharge duration settings.

[0082] Specifically, when the first bridge arm conducts, the conduction of the auxiliary tubes can be controlled in advance, so as to provide sufficient discharge duration for the discharge of the clamping capacitor, achieve the full discharge of the clamping capacitor, and thus ensure the voltage sharing between the series main power devices in the device series converter, improving the safety and reliability of the entire device series converter.

[0083] As an optional embodiment, it further includes:

[0084] Determine the current sum value of the capacitance voltages of all the clamping capacitors, and determine the difference between the current sum value and the bus voltage of the device series converter;

[0085] Determine the conduction duration of the auxiliary tubes based on the difference; the conduction duration of the auxiliary tubes is positively correlated with the difference, and the difference between the difference and the first preset duration is less than the preset dead-time from the turn-off of the main power device in the first bridge arm to the turn-on of the main power device in the second bridge arm.

[0086] It can be understood that the conduction duration of the auxiliary tube can be set according to the specific situation of the pressure difference. The pressure difference refers to the difference between the sum of the capacitor voltages of all clamping capacitors and the bus voltage of the device series converter. When the pressure difference is relatively large, it indicates that the clamping capacitors are charged with more electricity. At this time, a longer discharge duration is required to ensure the full discharge of the clamping capacitors. When the pressure difference is relatively small, it indicates that the clamping capacitors are charged with less electricity. At this time, only a shorter discharge duration is required to ensure the full discharge of the clamping capacitors. Considering that the dead time of the alternating conduction of the converter is generally fixed, the conduction duration of the auxiliary tube in the dead zone is usually set to a fixed value, and the conduction duration of the auxiliary tube is adjusted by adjusting the first preset duration. The specific determination method of the conduction duration of the auxiliary tube is not particularly limited in this application. A corresponding relationship between the pressure difference and the conduction duration of the auxiliary tube can be established in advance, and the conduction duration of the auxiliary tube can be determined directly by referring to the corresponding relationship table and other methods.

[0087] In practical applications, the conduction duration of the auxiliary tube is generally directly determined in advance according to the circuit topology and circuit parameters of the device series converter. The initially determined conduction duration can usually directly ensure the effective discharge of the clamping capacitors and ensure the clamping effect of the clamping capacitors. During the control process, the conduction duration of the auxiliary tube can also be further adjusted according to the method provided in this embodiment, so that the discharge of the clamping capacitors can be closer to the real-time working state, and ensure that the clamping capacitors can be discharged to a state where the pressure difference between the sum of the capacitor voltages of all clamping capacitors and the bus voltage of the device series converter is less than the preset value.

[0088] Specifically, considering that there is a direct positive correlation between the pressure difference between the sum of the capacitor voltages of all clamping capacitors and the bus voltage of the device series converter and the required discharge duration, this positive correlation can be directly used to determine the conduction duration of the auxiliary tube, which is convenient, effective, easy to implement, and improves the accuracy and reliability of the control process of the clamping capacitor discharge.

[0089] Please refer to Figure 9 , Figure 9 FIG. is a schematic diagram of the switching delay control of a device series converter provided by the present invention; as an optional embodiment, the first arm or the second arm is used as the target arm for driving delay adjustment, and based on the voltage of each clamping capacitor in the same arm being consistent, the driving delay of the corresponding main power device on the corresponding arm is adjusted respectively for each clamping capacitor in the same arm, including:

[0090] Obtain the current voltages of the respective clamping capacitors in the target arm every several switching cycles;

[0091] For any clamping capacitor in the target bridge arm, subtract the current voltage of the clamping capacitor from the reference voltage to obtain a voltage difference; wherein, the reference voltage is the target voltage with the same voltage as the clamping capacitor.

[0092] Input the calculated voltage difference into a compensator to obtain the driving delay of the main power device corresponding to the voltage of the clamping capacitor, so as to control the operation of each main power device based on the obtained driving delay; the compensator includes at least one integral link.

[0093] It is not difficult to understand that, as Figure 9 shown, the current voltages of each clamping capacitor are sampled by a voltage sensor and uploaded to a controller, and the controller obtains the delay time of the driving signals of each series-connected main power device based on the received current voltages of the clamping capacitors. When the driving delays of the driving signals of the main power devices are different, the specific charging duration of the corresponding clamping capacitor is different. Therefore, by continuously and dynamically adjusting the driving delays of the driving signals of each main power device, the driving delays of each main power device corresponding to the situation where the capacitor voltages of each clamping capacitor are the same can be found, so as to adjust the driving delays of each series-connected main power device to achieve the balance of the clamping capacitor voltages. The specific determination method of the driving delay and the like are not particularly limited in this application, and methods such as traversal and exhaustion can be used to implement it. The driving delay of the main power device can be realized by the controller delaying the output of the driving signal corresponding to the main power device and other methods, which are not particularly limited in this application. The specific type and implementation method of the driving signal of the main power device are not particularly limited in this application, and pulse signals and other methods can be used to implement it. For each main power device, there is a corresponding driving delay adjustment unit. Therefore, the control module of the converter includes N driving delay adjustment units corresponding to the N main power devices one by one, and the output signals of each driving delay adjustment unit act on the driving signals of the corresponding main power devices respectively.

[0094] It can be understood that due to the existence of the ACM module, the clamping capacitor can clamp the voltage of the corresponding main power device, and the voltage of the clamping capacitor does not increase significantly in a short time. Therefore, the asynchronous switching in a short time will not cause overvoltage damage to the series-connected devices, and the bandwidth requirement for the driving signal delay control is relatively low. At the same time, the voltage difference of the clamping capacitor generated by the asynchronous charging in one switching period may be less than the sensor accuracy and other reasons and cannot be distinguished; therefore, the operations of determining the driving delay of the main power device and adjusting the main power device can be performed every k switching periods, and the specific value of k is selected according to the actual circuit parameters, which are not particularly limited in this application.

[0095] It should be noted that, in order to obtain an accurate driving delay, a compensator capable of obtaining the driving delay according to the voltage difference is pre-constructed. The compensator includes at least a proportional link and an integral link. After the sensor samples the voltage of the clamping capacitor, the controller further calculates the voltage difference corresponding to the clamping capacitor, and then inputs it into the compensator. The compensator will adjust the voltage v c in the direction towards being equal to v ref (reference voltage). The output signal is the specific time adjustment amount of the driving delay, that is, Figure 10 the active delay time shown. Specifically, the determination of the driving delay can be achieved by presetting the adjustment amount of the driving delay in the compensator and other methods. The compensator outputs the active delay time and distributes it to the driving signals corresponding to each main power device, eliminating the asynchronous time between the driving signals of each main power device connected in series in the device series module, and thus eliminating the charging amount introduced due to switching asynchrony. For the specific type and implementation method of the compensator, etc., this application does not make special limitations here. The sample and hold circuit can perform certain amplification operations on the voltage difference. A sampling switch is arranged at the front end of the compensator, and the sampling switch closes every k switching cycles, so as to perform the adjustment of the driving delay every k switching cycles.

[0096] Specifically, while discharging the clamping capacitor to avoid the influence of commutation on the voltage equalization function of the clamping capacitor, the switching synchronization of the main power devices can also be achieved by adjusting the driving signal delay of the main power devices, thereby avoiding the influence of switching asynchrony on the voltage equalization function of the clamping capacitor. Based on the voltage of the clamping capacitor, the dynamic driving signal delay is adjusted, further ensuring the voltage equalization between the main power devices connected in series in the device series type converter, and improving the safety and reliability of the entire device series type converter.

[0097] As an optional embodiment, the determination process of the reference voltage includes:

[0098] Arbitrarily select one of the current voltages of all the clamping capacitors in the target arm and determine it as the reference voltage;

[0099] Or,

[0100] Determine the average value of the current voltages of all the clamping capacitors in the target arm as the reference voltage;

[0101] Or,

[0102] Determine the weighted average of the voltages of any one or more clamping capacitors in the target arm as the reference voltage.

[0103] It is not difficult to understand that the capacitor voltages of each clamping capacitor need to be adjusted to a consistent state ultimately. Therefore, it is necessary to first determine a reference voltage as the adjustment target. To reduce the adjustment amount, the reference voltage can be directly selected according to the voltage conditions of the clamping capacitors, or the reference voltage can be set in advance according to the actual situation. This application does not make special limitations here. The reference voltage V is directly determined by the voltage of the clamping capacitor. ref There are also three ways to select. The first way is to select the voltage of one of the N clamping capacitors as the reference voltage, which can be achieved by selecting the median of the voltages of the N clamping capacitors and other methods. The second way is to select the average value of the voltages of the N clamping capacitors. The third way is to select the weighted average value of the voltages of one or more clamping capacitors. At the same time, considering that when the difference between the voltage of the clamping capacitor and the reference voltage is larger, the main power device corresponding to the clamping capacitor needs to be configured with a larger drive delay to be consistent with other main power devices. Therefore, the drive delays of each main power device can be directly determined by using the positive correlation between the drive delay of the main power device and the voltage difference. When the voltage of the clamping capacitor is greater than the reference voltage, the greater the voltage of the clamping capacitor, that is, the greater the voltage difference, the larger the drive delay needs to be configured for the main power device. When the voltage of the clamping capacitor is less than the reference voltage, the smaller the voltage of the clamping capacitor, that is, the greater the voltage difference, the larger the negative drive delay needs to be configured for the main power device to advance the drive signal of the main power device. Therefore, the absolute value of the drive delay is positively correlated with the voltage difference. A positive drive delay means delaying the drive signal of the main power device, and a negative drive delay means advancing the drive signal of the main power device.

[0104] Specifically, directly determining the reference voltage by the voltage of the clamping capacitor makes the entire delay regulation process closer to the actual working state of the device series module, without the need to introduce additional voltage values, which is simple, effective, and easy to implement.

[0105] Please refer to Figure 10 , Figure 10 which is a control block diagram for adjusting the switch delay of a device series type converter provided by the present invention; please refer to Figure 11 , Figure 11 which is a waveform schematic diagram for adjusting the switch delay of a device series type converter provided by the present invention; As an optional embodiment, after inputting the calculated voltage difference into a compensator to obtain the drive delay of the main power device corresponding to the clamping capacitor voltage, it further includes:

[0106] Updating the delay register based on the obtained drive delay of the main power device every several switching cycles.

[0107] It can be understood that, in order to facilitate the control module of the converter to determine the driving delay of each main power device when generating the driving signals of each total power device, a delay register can be added at the output end of the compensator in the driving delay adjustment unit to store the driving delay finally obtained by the driving delay adjustment unit. The driving delay is determined every several switching cycles, so the delay register is also updated every several switching cycles. The control module directly generates the driving signals of each total power device according to the updated value in the delay register, and applies it to the original driving signal to generate the driving signal finally input to the control end of the controlled object.

[0108] As a specific embodiment, as Figure 11 shown, for the N driving signals from g1 to g N to adjust the driving delay of the corresponding N main power devices from S1 to S N by adjusting the turn-off time of the main power device. The dotted line in the figure is the falling edge of the driving signal before adjusting the driving delay. By delaying the falling edge of the driving signal g1, that is, the turn-off time of the main power device S1, by Δt d1 , advancing the falling edge of the driving signal g2, that is, the turn-off time of the main power device S2, by Δt d2 , and advancing the falling edge of the driving signal g N , that is, the turn-off time of the main power device S N by Δt dN , so that the N main power devices from S1 to S N reach synchronous turn-off.

[0109] Please refer to Figure 12 , Figure 12 which is a schematic diagram of a driving signal delay adjustment method for a main power device provided by the present invention; as an optional embodiment, when the output result of the delay register is positive, the driving delay of the main power device is the delay time of the turn-off time of the main power device and / or the advance time of the turn-on time of the main power device;

[0110] when the output result of the delay register is negative, the driving delay of the main power device is the advance time of the turn-off time of the main power device and / or the delay time of the turn-on time of the main power device.

[0111] Considering that the difference between the currently calculated voltage and the reference voltage in the closed-loop control system is negatively correlated with the amount of delay in the output of the compensator, a -1 coefficient can also be added at the front end of the compensator. After multiplying the reference voltage by -1, it is input into the compensator so that the compensator outputs an adjustment signal for finally driving the delay. At this time, the absolute value of the adjustment signal of the driving delay stored in the delay register is the amount of delay time, and its positive or negative represents the specific method of adjusting the driving delay. The adjustment methods of the driving delay include actively controlling the turn-on time / turn-off time of the main power device to be advanced or delayed. Figure 12 The arrow indicates the positive direction. Three different delay adjustment methods can be selected. The first is to adjust the delay of the turn-off time. If the adjustment signal is positive, the adjustment signal output by the delay register is the time for the main power device to turn off later. If the adjustment signal is negative, its absolute value represents the time for the main power device to turn off earlier. The second is to adjust the delay of the turn-on time. If the adjustment signal is positive, the adjustment signal output by the delay register is the time for the main power device to turn on earlier. If the adjustment signal is negative, its absolute value represents the time for the main power device to turn on later. The third is to adjust both the turn-on time and the turn-off time simultaneously. If the adjustment signal is positive, the adjustment signal output by the delay register is the time for the main power device to turn on earlier and the time for the main power device to turn off later. If the adjustment signal is negative, its absolute value represents the time for the main power device to turn on later and the time for the main power device to turn off earlier. Among them, a preferred embodiment is to adjust the delay of the turn-off time.

[0112] It should be noted that the switching asynchrony between the main power devices is not only caused by the asynchrony of the driving signals, but also may be caused by differences in transmission lines, device parasitic parameters, etc. in the circuit. Therefore, during the delay regulation process, the original delay time corresponding to the main power device will be determined in advance according to factors such as transmission lines and device parasitic parameters in the circuit. On the basis of the active delay time output by the compensator, the original delay time will be further supplemented to eliminate the switching asynchrony of the main power device caused by various factors. The specific value and determination method of the original delay time are not particularly limited in this application.

[0113] As a specific embodiment, please refer to Figure 13 , Figure 13 which is a schematic diagram of the signal waveform of the switching delay adjustment process of a device series converter provided by the present invention; taking 6 main power devices as an example, Figure 13 the simulation results of the process of using the switching delay adjustment method to ensure the voltage sharing of the main power devices in the Boost circuit are given, where V dc =3kV, and each arm is composed of 6 series-connected devices. The switching frequency is 20kHz, and switching delays of 0, 10ns, 30ns, 50ns, 90ns, and 110ns are set for the 6 series-connected devices respectively, and Vref = v c6, k = 10 (PI regulation is performed every 10 switching cycles). The abscissas of the two waveforms are both time, with the unit of seconds (s). The ordinate of the upper waveform is voltage, with the unit of V. The six colors respectively represent the clamped capacitor voltages corresponding to the six main power devices. The ordinate of the lower waveform is time, with the unit of seconds, and the colors correspond to those of the upper waveform, respectively representing the delay time adjustment amounts corresponding to the six main power devices output by the compensator. According to the simulation results, after adopting the Figure 10 control method shown, the voltage unbalance degree of the capacitor voltage is less than 3% in the starting stage, and good balance is achieved in the steady state, thus ensuring the voltage balance of each series device. In this embodiment, only the application of 6 devices connected in series in the Boost circuit is used as a simulation case, and the simulation results of other series numbers or other circuit topologies are similar, which will not be elaborated herein by the present invention.

[0114] Specifically, based on the sampled clamped capacitor voltage, the driving signal delay time of the main power device is adjusted by using PI control to make the series devices switch synchronously, eliminating the charging amount introduced by asynchronous switching. Based on the dynamic driving signal delay adjustment of the clamped capacitor voltage, it has the characteristics of low requirement for the response speed of adjustment and an additional discharge loop; through the setting of the sample and hold circuit and the compensator, the determination of the switching delay adjustment amount corresponding to each main power device is effectively realized.

[0115] To solve the above technical problems, the present invention also provides a control device for a device series-connected converter. The device series-connected converter at least includes a half-bridge circuit. The half-bridge circuit includes a first bridge arm and a second bridge arm connected in series. The first bridge arm and / or the second bridge arm both include a plurality of main power devices connected in series. An active clamping circuit is connected in parallel at both ends of each main power device. The active clamping circuit includes an auxiliary tube and a clamping capacitor connected in series. The main power devices of the first bridge arm and the second bridge arm conduct alternately; the control device of the device series-connected converter includes:

[0116] A driving adjustment unit, which is used to target the voltages of all the clamped capacitors in the same bridge arm to be the same, and respectively adjust the driving delays of the corresponding main power devices on the corresponding bridge arm based on the voltages of the respective clamped capacitors in the same bridge arm, so as to subsequently control the actions of each main power device based on the adjusted driving delays;

[0117] A differential pressure discharge unit, which is used to control the conduction of the auxiliary tubes corresponding to all the main power devices of the second bridge arm before the main power devices of the second bridge arm conduct when the device series-connected converter switches from the state where the first bridge arm conducts to the state where the second bridge arm conducts; when the on-time duration of the auxiliary tube reaches the total preset duration, control the turning-off of the auxiliary tubes corresponding to all the main power devices of the second bridge arm;

[0118] The main power device driving unit is used to control the first arm and the second arm to conduct alternately; after all the auxiliary tubes corresponding to the main power devices in the second arm are turned off, the main power devices in the second arm are respectively controlled to conduct and turn off based on the adjusted driving delay, so as to realize the balance of the clamping capacitor voltage and the voltage equalization of the main power devices.

[0119] The differential pressure discharge unit includes a commutation start unit, a differential pressure discharge sub-unit, and a commutation end unit;

[0120] The commutation start unit is used to control all the auxiliary tubes corresponding to the main power devices in the second arm to conduct before the main power devices in the second arm conduct when the device series converter switches from the state where the first arm conducts to the state where the second arm conducts;

[0121] The differential pressure discharge unit is used to control all the auxiliary tubes corresponding to the main power devices in the second arm to turn off when the on-time of the auxiliary tubes reaches the total preset time;

[0122] The commutation end unit is used to respectively control the main power devices in the second arm to conduct and turn off based on the adjusted driving delay after all the auxiliary tubes corresponding to the main power devices in the second arm are turned off, so as to realize the balance of the clamping capacitor voltage and the voltage equalization of the main power devices.

[0123] For the introduction of a control device for a device series converter provided by the present invention, please refer to the embodiments of the control method of the device series converter described above, and the present invention will not be elaborated here.

[0124] Please refer to Figure 14 , Figure 14 which is a schematic structural diagram of an electronic device provided by the present invention; to solve the above technical problems, the present invention also provides an electronic device, including:

[0125] A memory 21 for storing computer programs;

[0126] A processor 22 for implementing the steps of the control method of the device series converter as described above.

[0127] Among them, the processor 22 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 22 may be implemented in at least one hardware form of a DSP (Digital Signal Processor), an FPGA (Field-Programmable Gate Array), or a PLA (Programmable Logic Array). The processor 22 may also include a main processor and a coprocessor. The main processor is a processor used to process data in the wake state, also known as the central processor; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor 22 may integrate a GPU (graphics processing unit), and the GPU is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 22 may further include an AI (Artificial Intelligence) processor, and the AI processor is used to process computational operations related to machine learning.

[0128] The memory 21 may include one or more computer-readable storage media, and the computer-readable storage media may be non-transitory. The memory 21 may further include high-speed random access memory and non-volatile memory, such as one or more disk storage devices and flash storage devices. In this embodiment, the memory 21 is at least used to store the following computer programs. After the computer programs are loaded and executed by the processor 22, the relevant steps of the control method of the device series-connected converter disclosed in any one of the foregoing embodiments can be implemented. In addition, the resources stored in the memory 21 may also include an operating system and data, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system may include Windows, Unix, Linux, etc. The data may include, but is not limited to, the data of the control method of the device series-connected converter, etc.

[0129] In some embodiments, the electronic device may further include a display screen, an input / output interface, a communication interface, a power supply, and a communication bus.

[0130] Those skilled in the art can understand that Figure 14 the structure shown in

[0131] does not constitute a limitation on the electronic device, and it may include more or fewer components than those shown in the figure.

[0132] To solve the above technical problems, the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the control method of the device series-connected converter as described above are implemented.

[0133] It can be understood that if the method in the above embodiments is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and executes all or part of the steps of the methods described in the various embodiments of the present application. Specifically, the computer-readable storage medium may include, but is not limited to, any type of disk, including floppy disks, optical disks, and removable hard disks, etc., or any type of medium or device suitable for storing instructions and data, etc. The present application does not make a special limitation here.

[0134] For the introduction of the computer-readable storage medium provided by the present invention, please refer to the embodiments of the control method of the device series-connected converter described above, and the present invention will not be repeated here.

[0135] To solve the above technical problems, the present invention further provides a computer program product, including a computer program / instructions. When the computer program / instructions are executed by a processor, the steps of the control method of the device series-connected converter described above are implemented.

[0136] For the introduction of the computer program product provided by the present invention, please refer to the embodiments of the control method of the device series-connected converter described above, and the present invention will not be repeated here.

[0137] The various embodiments in this specification are described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0138] It should also be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0139] Those skilled in the art can further realize that the units and algorithm steps of each example described in connection with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to their functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0140] The steps of the methods or algorithms described in connection with the embodiments disclosed herein can be directly implemented by hardware, software modules executed by a processor, or a combination of the two. The software modules can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium well-known in the technical field.

[0141] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a device series converter, characterized in that, The device series converter includes at least one half - bridge circuit. The half - bridge circuit includes a first bridge arm and a second bridge arm connected in series. Each of the first bridge arm and / or the second bridge arm includes a plurality of main power devices connected in series. An active clamping circuit is connected in parallel across both ends of each main power device. The active clamping circuit includes an auxiliary transistor and a clamping capacitor connected in series. The main power devices of the first bridge arm and the main power devices of the second bridge arm conduct alternately; The control method of the device series converter includes: Aiming at the voltage of all the clamping capacitors in the same bridge arm being consistent, adjusting the driving delay of the corresponding main power device on the corresponding bridge arm respectively based on the voltage of each clamping capacitor in the same bridge arm, so as to control the actions of each main power device based on the adjusted driving delay subsequently; When the device series converter switches from the state where the first bridge arm conducts to the state where the second bridge arm conducts, before the main power device of the second bridge arm conducts, controlling the auxiliary transistors corresponding to all the main power devices of the second bridge arm to conduct; When the on - time of the auxiliary transistor reaches the total preset time, controlling the auxiliary transistors corresponding to all the main power devices of the second bridge arm to turn off; After the auxiliary transistors corresponding to all the main power devices of the second bridge arm turn off, controlling the conduction and turn - off of each main power device in the second bridge arm respectively based on the adjusted driving delay to achieve the balance of the clamping capacitor voltage and the voltage equalization of the main power devices.

2. The control method of the device series converter according to claim 1, characterized in that, Controlling the auxiliary transistors corresponding to all the main power devices of the second bridge arm to conduct includes: Determining the dead - time start moment when the device series converter switches from the state where the first bridge arm conducts to the state where the second bridge arm conducts; Taking the dead - time start moment as a reference, controlling the auxiliary transistors corresponding to all the main power devices of the second bridge arm to conduct in advance by a first preset time; the first preset time is less than the total preset time.

3. The control method of the device series converter according to claim 1 or 2, characterized in that, Taking the first bridge arm or the second bridge arm as the target bridge arm for driving delay adjustment, aiming at the voltage of all the clamping capacitors in the same bridge arm being consistent, adjusting the driving delay of the corresponding main power device on the corresponding bridge arm respectively based on the voltage of each clamping capacitor in the same bridge arm, includes: Obtaining the current voltage of each clamping capacitor in the target bridge arm every several switching cycles; For any clamping capacitor in the target bridge arm, subtracting the current voltage of the clamping capacitor from the reference voltage to obtain a voltage difference; where the reference voltage is the target voltage for the voltage of the clamping capacitors to be consistent; Inputting the calculated voltage difference into a compensator to obtain the driving delay of the main power device corresponding to the clamping capacitor voltage, so as to control the actions of each main power device based on the obtained driving delay; the compensator includes at least one integral link.

4. The control method of the device series converter according to claim 3, characterized in that, The determination process of the reference voltage includes: Arbitrarily selecting one of the current voltages of all the clamping capacitors in the target bridge arm and determining it as the reference voltage; Or, Determining the average value of the current voltages of all the clamping capacitors in the target bridge arm as the reference voltage; Or, Determine the weighted average of the voltages of any one or more clamping capacitors in the target bridge arm as the reference voltage.

5. The control method of the device series converter according to claim 3, characterized in that, After inputting the calculated voltage difference into a compensator to obtain the driving delay of the main power device corresponding to the clamping capacitor voltage, it further includes: Updating the delay register based on the obtained driving delay of the main power device every several switching cycles.

6. The control method of the device series converter according to claim 5, characterized in that, When the output result of the delay register is positive, the driving delay of the main power device is the delay time after the turn-off moment of the main power device and / or the leading time at the turn-on moment of the main power device; When the output result of the delay register is negative, the driving delay of the main power device is the leading time at the turn-off moment of the main power device and / or the delay time at the turn-on moment of the main power device.

7. A control device for a series-connected device converter, characterized in that, The device series-connected converter includes at least one half-bridge circuit. The half-bridge circuit includes a first bridge arm and a second bridge arm connected in series. The first bridge arm and / or the second bridge arm each include a plurality of main power devices connected in series. An active clamping circuit is connected in parallel across both ends of each main power device. The active clamping circuit includes an auxiliary transistor and a clamping capacitor connected in series. The main power devices of the first bridge arm and the main power devices of the second bridge arm conduct alternately. The control device of the device series-connected converter includes: A driving adjustment unit, which aims to make the voltages of all the clamping capacitors in the same bridge arm consistent, and adjusts the driving delay of the corresponding main power device on the corresponding bridge arm based on the voltages of each clamping capacitor in the same bridge arm, so as to control the actions of each main power device based on the adjusted driving delay subsequently. A voltage difference discharging unit, which, when the device series-connected converter switches from the state where the first bridge arm conducts to the state where the second bridge arm conducts, controls the auxiliary transistors corresponding to all the main power devices of the second bridge arm to conduct before the main power devices of the second bridge arm conduct; when the on-time of the auxiliary transistors reaches the total preset time, controls the auxiliary transistors corresponding to all the main power devices of the second bridge arm to turn off. A main power device driving unit, which controls the first bridge arm and the second bridge arm to conduct alternately; after the auxiliary transistors corresponding to all the main power devices of the second bridge arm turn off, controls the conduction and turn-off of each main power device in the second bridge arm based on the adjusted driving delay respectively, so as to achieve the balance of the clamping capacitor voltages and the equal voltage of the main power devices.

8. An electronic device, characterized in that, It includes: A memory for storing a computer program; A processor for implementing the steps of the control method of the device series-connected converter according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium. When the computer program is executed by the processor, it implements the steps of the control method of the device series-connected converter according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, it implements the steps of the control method of the device series-connected converter according to any one of claims 1 to 6.

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