Soft switching implementation method of converter, controller and storage medium

Abstract

The invention relates to the technical field of soft switching, particularly provides a soft switching implementation method of a converter, a controller and a storage medium, and aims to solve the problem of how to reduce hardware cost and switching loss required for implementing soft switching. In order to achieve the purpose, the method comprises the steps that the phase current value of each phase of bridge arm complementary unit in the current switching period and the direct-current bus voltage of the interleaving parallel converter are obtained so as to determine the phase shifting angle of the current switching period, and the phase angle between a first carrier wave and a second carrier wave is obtained according to the phase shifting angle to form a special-shaped carrier wave; and obtaining a pulse signal corresponding to each bridge arm according to the special-shaped carrier to realize soft switching. The special-shaped carrier wave of the current switching period is constructed according to the phase shift angle, and the pulse signals of the first bridge arm and the second bridge arm are generated in the special-shaped carrier wave, so that current polarity overturning can be realized according to the pulse signal difference, and soft switching of the converter is realized without connecting an additional zero-cross detection hardware circuit; and the switching loss of the switching device and the required hardware cost are reduced.

Description

Technical Field

[0001] The present application relates to the field of soft switching technology, and in particular to a method for implementing soft switching of a converter, a controller and a storage medium. Background Art

[0002] In recent years, converters are developing towards higher conversion efficiency, higher switching frequency, and greater power density. However, the large switching loss caused by high switching frequency is the main factor limiting the further improvement of converter efficiency. Since the turn-on loss of wide bandgap semiconductor materials used in electronic devices in converters accounts for the main part of switching loss, the development of converters towards soft switching is an inevitable trend in the development of power electronics technology. Compared with hard switching, which has disadvantages such as large switching loss and electromagnetic interference due to the simultaneous change of voltage and current during the switching process, soft switching can make the switching loss close to zero by controlling the change of voltage and current in sequence, thereby improving the efficiency and reliability of the system.

[0003] In the prior art, when the critical conduction mode (TCM) is used to implement soft switching, the diode does not undergo a reverse recovery process in the TCM mode, so an additional zero-crossing detection circuit is required, which increases the required hardware cost, and the switching frequency in the TCM mode is inconsistent in three phases and has a large fluctuation range, resulting in complex parameter design of the filter used to reduce the electromagnetic interference generated by the converter, and the problem of poor stability of converter control. When the quadrilateral current mode (QCM) is used to implement soft switching, there is a problem that the zero-crossing harmonics of the bridge arm current of each phase of the converter are too large when working at the zero point. The excessive harmonic current will have a greater impact on the on-state loss and turn-off loss of the converter, thereby resulting in a larger overall loss.

[0004] Accordingly, a new solution is needed in the art to solve the above problems. Application Contents

[0001] The present application aims to solve the above technical problem, that is, to solve the problem of how to reduce the switching loss and hardware cost of the converter to achieve soft switching.

[0005] In a first aspect, the present application provides a method for implementing soft switching of a converter.

[0006] The method is applicable to an interleaved parallel converter, wherein the interleaved parallel converter comprises a three-phase bridge arm complementary unit, wherein each phase bridge arm complementary unit comprises a first bridge arm and a second bridge arm, wherein the first bridge arm and the second bridge arm are connected in parallel, and each of the bridge arms comprises a pair of complementary switch devices connected in series; the method comprises:

[0007] Acquire the phase current value of the bridge arm complementary unit of each phase and the DC bus voltage of the staggered parallel converter in the current switching cycle;

[0008] For each phase bridge arm complementary unit, determine the phase shift angle corresponding to each phase bridge arm complementary unit in the current switching cycle according to the phase current value and the DC bus voltage;

[0009] According to the phase shift angle, a phase angle between a first carrier and a second carrier of a current switching cycle is obtained to form a special-shaped carrier, wherein the first carrier is a carrier for obtaining a pulse signal for controlling all switching devices on the first bridge arm, and the second carrier is a carrier for obtaining a pulse signal for controlling all switching devices on the second bridge arm;

[0010] According to the special-shaped carrier, a pulse width modulation signal corresponding to each bridge arm is obtained to control the switching state of all switching devices on each bridge arm, thereby realizing soft switching of the staggered parallel converter.

[0011] In one technical solution of the soft switching implementation method of the above converter,

[0012] The step of acquiring the phase angle between the first carrier and the second carrier of the current switching cycle according to the phase shift angle to form a special-shaped carrier comprises:

[0013] Acquire a first forward sawtooth wave and a second forward sawtooth wave, and set the phase angles of the first forward sawtooth wave and the second forward sawtooth wave to the phase shift angle, wherein the first forward sawtooth wave and the second forward sawtooth wave have the same shape and the same amplitude;

[0014] At the start time of the current switching cycle, setting the initial positions of the first forward sawtooth wave and the second forward sawtooth wave according to half of the phase shift angle;

[0015] Determining the first carrier and the second carrier according to the first forward sawtooth wave and the second forward sawtooth wave after the initial positions are set;

[0016] The alien carrier is determined according to the first carrier and the second carrier.

[0017] In one technical solution of the soft switching implementation method of the above converter,

[0018] The determining the first carrier and the second carrier according to the first forward sawtooth wave and the second forward sawtooth wave after the initial position is set includes:

[0019] Every two consecutive odd-numbered switching cycles and even-numbered switching cycles are regarded as a group of switching cycles;

[0020] Flipping the first forward sawtooth wave in the even-numbered switching cycles in each group of switching cycles horizontally along the abscissa axis to obtain the first carrier;

[0021] The second forward sawtooth wave in the even-numbered switching cycles in each group of switching cycles is horizontally flipped along the abscissa axis to obtain the second carrier.

[0022] In one technical solution of the soft switching implementation method of the above converter,

[0023] The first bridge arm includes a first switch device and a second switch device connected in series with the first switch device, and the second bridge arm includes a third switch device and a fourth switch device connected in series with the third switch device;

[0024] The step of obtaining a pulse width modulation signal corresponding to each bridge arm according to the heteromorphic carrier comprises:

[0025] According to the comparison result of the first carrier and the modulated wave, a first pulse signal is obtained, and the switching states of the first switching device and the second switching device are determined according to the first pulse signal, wherein the first pulse signal is a pulse width modulation signal corresponding to the first bridge arm, and the modulated wave is a non-sinusoidal wave used to obtain a pulse width modulation signal in combination with the special-shaped carrier;

[0026] According to the comparison result of the second carrier and the modulation wave, a second pulse signal is obtained, and the switching states of the third switching device and the fourth switching device are determined according to the second pulse signal, and the second pulse signal is a pulse width modulation signal corresponding to the second bridge arm.

[0027] In one technical solution of the soft switching implementation method of the above converter,

[0028] The step of obtaining a first pulse signal according to a comparison result between the first carrier wave and the modulated wave comprises:

[0029] When the amplitude of the modulated wave is greater than or equal to the amplitude of the first carrier, the first pulse signal is determined to be at a high level; when the amplitude of the modulated wave is less than the amplitude of the first carrier, the first pulse signal is determined to be at a low level;

[0030] The step of obtaining a second pulse signal according to a comparison result between the second carrier wave and the modulated wave comprises:

[0031] When the amplitude of the modulated wave is greater than or equal to the amplitude of the second carrier, the second pulse signal is determined to be a high level; when the amplitude of the modulated wave is less than the amplitude of the second carrier, the second pulse signal is determined to be a low level.

[0032] In one technical solution of the soft switching implementation method of the above converter,

[0033] The first switching device is complementary to the second switching device, and the third switching device is complementary to the fourth switching device;

[0034] The step of determining the switching states of the first switching device and the second switching device according to the first pulse signal comprises:

[0035] If the first pulse signal is at a high level, it is determined that the switch state of the first switch device is an on state, and the switch state of the second switch device is an off state;

[0036] If the first pulse signal is at a low level, it is determined that the switch state of the first switch device is an off state, and the switch state of the second switch device is an on state;

[0037] The step of determining the switching states of the third switching device and the fourth switching device according to the second pulse signal comprises:

[0038] If the second pulse signal is at a high level, it is determined that the switch state of the third switch device is an on state, and the switch state of the fourth switch device is an off state;

[0039] If the second pulse signal is at a low level, it is determined that the switching state of the third switch device is an off state, and the switching state of the fourth switch device is an on state.

[0040] In one technical solution of the soft switching implementation method of the above converter,

[0041] The bridge arm complementary unit of each phase further comprises two auxiliary inductors connected in parallel, one end of each of the auxiliary inductors is respectively connected to a series connection point between two switch devices on one of the bridge arms, the other end of each of the auxiliary inductors is connected to the output side of the bridge arm complementary unit, and the inductance values ​​of the two auxiliary inductors are the same;

[0042] The determining, according to the phase current value and the DC bus voltage, the phase shift angle corresponding to the bridge arm complementary unit of each phase of the current switching cycle comprises:

[0043] The first quantitative relationship between the interphase circulating current ripple, the phase shift angle and the DC bus voltage is determined according to the following formula:

[0044]

[0045] in, is the phase shift angle, V dc is the DC bus voltage, Ts is the length of the current switching cycle, ΔI rp is the interphase circulating current ripple flowing through the auxiliary inductor, L m is the inductance value of the auxiliary inductor;

[0046] Based on the critical soft switching condition, a second quantitative relationship between the interphase circulating current ripple and the phase current value is determined according to the following formula:

[0047]

[0048] Among them, i x is the phase current value, I bs The current value of the bias current of each of the switching devices, ΔI rp is the interphase circulating current ripple flowing through the auxiliary inductor;

[0049] The phase shift angle is obtained according to the first quantitative relationship and the second quantitative relationship.

[0050] In one technical solution of the soft switching implementation method of the above converter,

[0051] The obtaining the phase shift angle according to the first quantitative relationship and the second quantitative relationship comprises:

[0052] According to the modulation wave, the value range of the phase shift angle is determined according to the following formula:

[0053]

[0054] Among them, V ref The amplitude of the modulated wave of the pulse width modulation signal is obtained by comparing it with the amplitude of the shaped carrier wave. is the phase shift angle;

[0055] According to the first quantitative relationship and the second quantitative relationship, the following formula is determined to obtain the phase shift angle:

[0056]

[0057] in, is the phase shift angle, V dc is the DC bus voltage, T s is the length of the current switching cycle, i x is the phase current value, I bs The current value of the bias current for each of the switching devices, L m is an inductance value of the auxiliary inductor.

[0058] In a second aspect, a controller is provided, comprising at least one processor; and a memory communicatively connected to the at least one processor; wherein a computer program is stored in the memory, and when the computer program is executed by the at least one processor, the method described in any one of the technical solutions of the technical solution for implementing the soft switching of the above-mentioned converter is implemented.

[0059] In a third aspect, a computer-readable storage medium is provided, wherein a plurality of program codes are stored therein, wherein the program codes are suitable for being loaded and run by a processor to execute the method described in any one of the technical solutions of the soft switching implementation method of the above-mentioned converter.

[0060] The above one or more technical solutions of the present application have at least one or more of the following beneficial effects:

[0002] In the case of adopting the above-mentioned technical scheme, the present application includes: obtaining the phase current value of each phase bridge arm complementary unit in the current switching cycle and the DC bus voltage of the staggered parallel converter, and for each phase bridge arm complementary unit, determining the corresponding phase shift angle of each phase bridge arm complementary unit in the current switching cycle according to the phase current value and the DC bus voltage; obtaining the phase angle between the first carrier and the second carrier of the current switching cycle according to the phase shift angle to form a special-shaped carrier, wherein the first carrier is a carrier for obtaining a pulse signal for controlling all switching devices on the first bridge arm, and the second carrier is a carrier for obtaining a pulse signal for controlling all switching devices on the second bridge arm; according to the special-shaped carrier, obtaining a pulse width modulation signal corresponding to each bridge arm to control the switching state of all switching devices on each bridge arm, thereby realizing soft switching of the staggered parallel converter.

[0003] Through the above configuration, the present application determines the phase shift angle of the current cycle in real time according to the phase current value of each phase bridge arm complementary unit of the current switching cycle of the interleaved parallel converter and the DC bus voltage of the interleaved parallel converter, so as to use the dynamically updated phase shift angle to generate the interphase circulating current ripple that meets the critical soft switching conditions, solves the problem of excessive zero-crossing harmonics in the traditional soft switching method, reduces the switching loss of the switching device, and greatly improves the state conversion efficiency of the switching device. In addition, the special-shaped carrier of the current switching cycle can be constructed by the phase shift angle, and the first carrier and the second carrier in the special-shaped carrier are used to generate the pulse signal of the first bridge arm and the second bridge arm, and then the current polarity of the first bridge arm and the second bridge arm is reversed according to the pulse signal difference between the two bridge arms, and the soft switching of the converter can be realized without connecting an additional zero-crossing detection hardware circuit, thereby improving the power density and reducing the hardware cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The disclosure of the present application will become easier to understand with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present application. Among them:

[0062] Figure 1 is a flowchart of main steps of a method for implementing soft switching of a converter according to an embodiment of the present application;

[0063] Figure 2 is a circuit topology diagram of an interleaved parallel converter according to an embodiment of the present application;

[0064] Figure 3 is a control block diagram of an interleaved parallel converter based on heterogeneous carriers according to an implementation of an embodiment of the present application;

[0065] Figure 4 is a waveform diagram for representing a changing relationship between a phase shift angle and a phase current according to an embodiment of the present application;

[0066] Figure 5 It is a waveform diagram of a pulse signal obtained according to an irregular carrier according to an embodiment of the present application. DETAILED DESCRIPTION

[0067] Some embodiments of the present application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application and are not intended to limit the protection scope of the present application.

[0068] In the description of the present application, "module" and "processor" may include hardware, software or a combination of the two. A module may include hardware circuits, various suitable sensors, communication ports, memory, and may also include software parts, such as program code, or a combination of software and hardware. The processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor or any other suitable processor. The processor has data and / or signal processing functions. The processor may be implemented in software, hardware or a combination of the two. Computer-readable storage media include any suitable medium that can store program code, such as a disk, a hard disk, an optical disk, a flash memory, a read-only memory, a random access memory, etc. The term "A and / or B" means all possible combinations of A and B, such as only A, only B or A and B. The term "at least one A or B" or "at least one of A and B" has a similar meaning to "A and / or B" and may include only A, only B or A and B. The singular terms "one" and "the" may also include plural forms.

[0069] Here we first explain some terms involved in this application.

[0070] Soft switching can achieve zero voltage switching (Zero Voltage Switching, ZVS) by introducing resonance during the switching process of the converter, so that the voltage drops to zero before the switch is turned on, thereby eliminating or reducing the overlapping area of ​​voltage and current, significantly reducing switching losses and electromagnetic interference.

[0071] See attached Figure 1 , Figure 1 FIG. 1 is a flow chart of the main steps of a method for implementing soft switching of a converter according to an embodiment of the present application. Figure 1 As shown, the soft switching implementation method of the converter in the embodiment of the present application mainly includes the following steps S101 to S104.

[0072] Step S101: obtaining the phase current value of each phase bridge arm complementary unit and the DC bus voltage of the staggered parallel converter in the current switching cycle.

[0073] In this embodiment, this method is applicable to an interleaved parallel converter, which includes a three-phase bridge arm complementary unit, each phase bridge arm complementary unit includes a first bridge arm and a second bridge arm, the first bridge arm and the second bridge arm are connected in parallel, and each bridge arm includes a pair of complementary switching devices connected in series.

[0074] Among them, the interleaved parallel converter is a highly efficient topology that can achieve interleaved current distribution through interleaved control, thereby reducing the ripple of the output current and improving the stability and efficiency of the system. It is suitable for occasions with high power density and high efficiency requirements.

[0075] In one embodiment, the interleaved parallel converter can use silicon carbide (SiC) semiconductor material as a switching device. Silicon carbide is a third-generation wide bandgap semiconductor material, and generally, the turn-on loss of wide bandgap semiconductor materials accounts for the main part of the switching loss. Therefore, when the soft switching implementation method provided by the present method is implemented using silicon carbide switching devices, the overall loss of the soft switching can be reduced.

[0076] In one embodiment, please refer to the attached Figure 2 , attached Figure 2 is a schematic diagram of a circuit topology of an interleaved parallel converter according to an embodiment of the present application. Figure 2 As shown, the DC bus voltage of the interleaved parallel converter can be Figure 2 V dc , the interleaved parallel converter may include three-phase bridge arm complementary units.

[0077] In this embodiment, Figure 2 The output side of the interleaved parallel converter is connected through the output filter inductor L o Finally, connect to the grid or load.

[0078] In this embodiment, the three-phase bridge arm complementary unit may include a phase bridge arm complementary unit, b phase bridge arm complementary unit and c phase bridge arm complementary unit. The phase current value of each phase bridge arm complementary unit may include Figure 2 i a 、i b and i c .

[0079] In this embodiment, each phase bridge arm complementary unit may include two bridge arms, such as Figure 2 The a-phase bridge arm complementary unit may include a switch device S a1 and S' a2 The bridge arm and the other one includes a switching device S a2 and S' a2 The bridge arm of phase b can include a bridge arm having a switching device S b1 and S' b1 The bridge arm and the other one includes a switching device S b2 and S' b2 The bridge arm of the c-phase bridge arm complementary unit may include a switching device S c1 and S' c1 The bridge arm and the other one includes a switching device S c2 and S' c2 The bridge arm. Among them, the switching device S a1 and S' a2 Complementary, switching device S a2 and S' a2 Complementary; Switching Device S b1 and S' b1 Complementary, switching device S b2 and S' b2 Complementary; Switching Device S c1 and S' c1 Complementary; Switching Device S c2 and S' c2 Complementary.

[0080] In one embodiment, each phase bridge arm complementary unit may further include two auxiliary inductors connected in parallel, one end of each auxiliary inductor is connected to the series connection point between two switch devices on one bridge arm, and the other end of each auxiliary inductor is connected to the output side of the bridge arm complementary unit. Figure 2 As shown, the phase a bridge arm complementary unit may include an auxiliary inductor L am1 and L am2 The b-phase bridge arm complementary unit may include an auxiliary inductor L bm1 and L bm2 , the c-phase bridge arm complementary unit may include an auxiliary inductor Lcm1 and L cm2 .

[0081] In this embodiment, the switching cycle refers to the time interval for the switching device to switch between the switching states. Specifically, the switching cycle (Ts) is the time required for the switching device to switch from the on state to the off state, and then from the off state to the on state. During this cycle, the on time (T on ) and the turn-off time (T off ) equals one complete switching cycle.

[0082] Step S102: for each phase bridge arm complementary unit, determine the phase shift angle corresponding to each phase bridge arm complementary unit in the current switching cycle according to the phase current value and the DC bus voltage.

[0083] In this embodiment, the phase shift angle refers to the difference in phase between two related signals, and is used to determine the phase difference between the first carrier and the second carrier in the heterogeneous carrier.

[0084] In this embodiment, if the phase current values ​​corresponding to the bridge arm complementary units of each phase are different, the phase shift angles corresponding to the bridge arm complementary units of each phase are also different, and the final obtained special-shaped carriers are also different.

[0085] In one embodiment, each phase bridge arm complementary unit also includes two auxiliary inductors connected in parallel, one end of each auxiliary inductor is respectively connected to the series connection point between two switching devices on a bridge arm, and the other end of each auxiliary inductor is connected to the output side of the bridge arm complementary unit, and the inductance values ​​of the two auxiliary inductors are the same.

[0086] In this implementation, step S102 may further include steps S1021 to S1023:

[0087] Step S1021: Determine a first quantitative relationship between the interphase circulating current ripple, the phase shift angle, and the DC bus voltage according to the following formula (1):

[0088]

[0089] in, is the phase shift angle, V dc is the DC bus voltage, T s is the length of the current switching cycle, ΔI rp is the interphase circulating current ripple flowing through the auxiliary inductor, L m is the inductance value of an auxiliary inductor.

[0090] In this embodiment, the interphase circulating current is the current between two auxiliary inductors generated in each phase bridge arm complementary unit due to different voltages on the two bridge arms. The interphase circulating current ripple is the amplitude fluctuation range of the interphase circulating current, which fluctuates around zero.

[0091] Step S1022: Based on the critical soft switching condition, determine the second quantitative relationship between the interphase circulating current ripple and the phase current value according to the following formula (2):

[0092]

[0093] Among them, i x is the phase current value, I bs The current value of the bias current for each switching device, ΔI rp is the interphase circulating current ripple flowing through the auxiliary inductor.

[0094] In this embodiment, the critical soft switching condition can be obtained by setting the phase shift angle to the minimum value within the value range, limiting the current value of the bridge arm current of each bridge arm to be greater than or equal to the bias current, etc., so that each switching device operates in the critical soft switching mode.

[0095] Step S1023: Obtain a phase shift angle according to the first quantitative relationship and the second quantitative relationship.

[0096] In one implementation, step S1023 may further include steps S10231 to S10232:

[0097] Step S10231: Determine the value range of the phase shift angle according to the modulation wave.

[0098] In this embodiment, the value range can refer to the following formula (10):

[0099]

[0100] Among them, V ref The amplitude of the modulated wave of the pulse width modulation signal is obtained by comparing it with the amplitude of the shaped carrier wave. is the phase shift angle.

[0101] Step S10232: According to the first quantitative relationship and the second quantitative relationship, determine the following formula to obtain the phase shift angle, which can be seen from formula (11):

[0102]

[0103] in, is the phase shift angle, V dc is the DC bus voltage, T s is the length of the current switching cycle, i xis the phase current value, I bs The current value of the bias current for each switching device, L m is the inductance value of an auxiliary inductor.

[0104] In this embodiment, since or 2πV ref When the bridge arm current cannot always reach the bias current I bs , the full range of soft switching of the interleaved parallel converter cannot be achieved, so it is necessary to limit The value range of .

[0105] Step S103: According to the phase shift angle, the phase angle between the first carrier and the second carrier of the current switching cycle is obtained to form a special-shaped carrier.

[0106] In this embodiment, the first carrier is a carrier for obtaining a pulse signal for controlling all switching devices on the first bridge arm, and the second carrier is a carrier for obtaining a pulse signal for controlling all switching devices on the second bridge arm.

[0107] In one implementation, a pair of forward sawtooth waves with a phase difference may be used to obtain the first carrier and the second carrier.

[0108] In one implementation, step S103 may further include:

[0109] Step S1031: acquiring a first forward sawtooth wave and a second forward sawtooth wave, and setting the phase angles of the first forward sawtooth wave and the second forward sawtooth wave as phase shift angles.

[0110] In this embodiment, the first forward sawtooth wave and the second forward sawtooth wave have the same shape and the same amplitude.

[0111] In one implementation, the second forward sawtooth wave may be obtained by translating the first forward sawtooth wave.

[0112] Step S1032: at the start time of the current switching cycle, the initial positions of the first forward sawtooth wave and the second forward sawtooth wave are set according to half of the phase shift angle.

[0113] In one embodiment, in order to ensure that the bridge arm current of all bridge arms can reach the bias current I bs The first forward sawtooth wave and the second forward sawtooth wave with a phase angle of the phase shift angle φ can be simultaneously phase-shifted by 0.5φ at the start of each switching cycle to ensure that all switch tubes in the staggered parallel converter can achieve soft switching.

[0114] Step S1033: determining the first carrier and the second carrier according to the first forward sawtooth wave and the second forward sawtooth wave after the initial position is set.

[0115] In one embodiment, since the time that the pulse signals corresponding to the first forward sawtooth wave and the second forward sawtooth wave can keep the interphase circulating current generated by the staggered parallel converter at the maximum and minimum values ​​is not equal after the initial position is determined, in the actual operation process, due to dead time, parasitic parameters and other unavoidable error factors, the phases of the two bridge arm currents in each phase bridge arm complementary unit are likely to gradually shift. Therefore, the first forward sawtooth wave and the second forward sawtooth wave in the latter switching cycle of two adjacent switching cycles can be horizontally flipped along the time horizontal axis to obtain the final first carrier and second carrier.

[0116] In one implementation, step S1033 may further include:

[0117] Step S10331: every two consecutive odd-numbered switching cycles and even-numbered switching cycles are regarded as a group of switching cycles.

[0118] Step S10332: horizontally flip the first forward sawtooth wave in the even-numbered switching cycles in each group of switching cycles along the abscissa axis to obtain a first carrier.

[0119] Step S10333: horizontally flip the second forward sawtooth wave in the even-numbered switching cycles in each group of switching cycles along the horizontal axis to obtain a second carrier.

[0120] Step S1034: Determine a heterogeneous carrier according to the first carrier and the second carrier.

[0121] In this implementation, the special-shaped carrier is a pre-set waveform that can be adjusted in real time according to the phase shift angle, and may include a first carrier and a second carrier.

[0122] In one implementation, the first forward sawtooth wave and the second forward sawtooth wave in the odd switching cycle may also be horizontally flipped along the horizontal axis, without affecting the normal implementation of the embodiment of the present application.

[0123] Step S104: According to the heterogeneous carrier, a pulse width modulation signal corresponding to each bridge arm is obtained to control the switching state of all switching devices on each bridge arm to achieve soft switching of the staggered parallel converter.

[0124] In this embodiment, pulse width modulation (PWM) is a technology commonly used in digital circuit control, which can convert a continuous analog signal into a series of discrete pulses and control the circuit output by adjusting the width of the pulse signal. For example, when the pulse width modulation signal is a high voltage, a switch device on a bridge arm that is preset can be controlled to be adjusted to an on state and another switch device to an off state; when the pulse width modulation signal is a low level, the switch states of the two switch devices are switched.

[0125] In this implementation, the pulse width modulation signal corresponding to each bridge arm may include a pulse width modulation signal corresponding to the first bridge arm and a pulse width modulation signal corresponding to the second bridge arm in each phase bridge arm complementary unit.

[0126] In one embodiment, the first bridge arm in each phase bridge arm complementary unit includes a first switching device and a second switching device connected in series with the first switching device, and the second bridge arm includes a third switching device and a fourth switching device connected in series with the third switching device.

[0127] In one embodiment, the first switching device is complementary to the second switching device, and the third switching device is complementary to the fourth switching device.

[0128] In this implementation, step S104 may further include:

[0129] Step S1041: obtaining a first pulse signal according to the comparison result between the first carrier wave and the modulated wave, and determining the switching states of the first switching device and the second switching device according to the first pulse signal.

[0130] In this embodiment, the first pulse signal is a pulse width modulation signal corresponding to the first bridge arm.

[0131] Step S1042: Obtain a second pulse signal according to the comparison result between the second carrier wave and the modulated wave, and determine the switching states of the third switching device and the fourth switching device according to the second pulse signal.

[0132] In this embodiment, the second pulse signal is a pulse width modulation signal corresponding to the second bridge arm.

[0133] In this implementation, the modulated wave is generally a non-sinusoidal wave used to perform signal modulation in combination with a special-shaped carrier to obtain a pulse width modulated signal.

[0134] In one embodiment, the modulated wave may be a saddle wave. The saddle wave is a waveform used in space vector pulse width modulation, which is essentially a waveform obtained by superimposing a sine wave with a triangular wave of three times the fundamental frequency. The main function is to improve the utilization rate of the voltage by superimposing a negative voltage when the phase voltage is large to make the whole move downward, and superimposing a positive voltage when the phase voltage is small to make the whole move upward.

[0135] In one implementation, obtaining the first pulse signal may specifically include the following steps S10411 to S10412:

[0136] Step S10411: When the amplitude of the modulated wave is greater than or equal to the amplitude of the first carrier wave, determine that the first pulse signal is at a high level.

[0137] Step S10412: When the amplitude of the modulated wave is smaller than the amplitude of the first carrier wave, determine that the first pulse signal is at a low level.

[0138] In one implementation, obtaining the second pulse signal may specifically include the following steps S10421 to S10422:

[0139] Step S10421: When the amplitude of the modulated wave is greater than or equal to the amplitude of the second carrier wave, determine that the second pulse signal is a high level.

[0140] Step S10422: When the amplitude of the modulated wave is smaller than the amplitude of the second carrier wave, determine that the second pulse signal is at a low level.

[0141] In this implementation, when the amplitude of the carrier wave is equal to the amplitude of the modulation wave, the level information of the pulse signal may not change, and maintain the original high level or low level state.

[0142] In one embodiment, determining the switching states of the first switching device and the second switching device according to the first pulse signal in step S1041 may further include steps S10511 to S10512:

[0143] Step S10511: If the first pulse signal is at a high level, it is determined that the switch state of the first switch device is an on state, and the switch state of the second switch device is an off state.

[0144] Step S10512: If the first pulse signal is at a low level, it is determined that the switch state of the first switch device is an off state, and the switch state of the second switch device is an on state.

[0145] In this embodiment, the first pulse signal is at a high level, which is equivalent to the modulated wave in the above embodiment being greater than or equal to the amplitude of the first carrier; the first pulse signal is at a low level, which is equivalent to the modulated wave in the above embodiment being less than the amplitude of the first carrier.

[0146] In one embodiment, determining the switching states of the third switching device and the fourth switching device according to the second pulse signal in step S1042 may further include steps S10521 to S10522:

[0147] Step S10521: if the second pulse signal is at a high level, determining that the switch state of the third switch device is an on state, and the switch state of the fourth switch device is an off state;

[0148] Step S10522: if the second pulse signal is at a low level, determine that the switch state of the third switch device is an off state, and the switch state of the fourth switch device is an on state.

[0149] In this embodiment, the second pulse signal is at a high level, which is equivalent to the modulated wave in the above embodiment being greater than or equal to the amplitude of the second carrier; the second pulse signal is at a low level, which is equivalent to the modulated wave in the above embodiment being less than the amplitude of the second carrier.

[0150] In an application scenario according to an embodiment of the present application, please refer to the attached Figure 3 , attached Figure 3 1 is a control block diagram of an interleaved parallel converter based on heterogeneous carriers according to an implementation of an embodiment of the present application. Figure 3 As shown, the method may specifically include:

[0151] Step S301: Obtain the phase current i of each phase bridge arm complementary unit x , the input side current V of the interleaved parallel converter dc , and the cycle frequency f of each switching cycle s .

[0152] Step S302: According to i x 、V dc and f s Calculate the phase shift angle φ x .

[0153] Step S303: According to the modulation wave V x_ref , limit φ x The value range of .

[0154] Step S304: According to φ x A special-shaped carrier is constructed, and a pulse signal is generated according to the special-shaped carrier to control each switch device of the bridge arm complementary unit.

[0155] In this embodiment, if Figure 3 As shown, the interleaved parallel converter includes a phase a bridge arm complementary unit, a phase b bridge arm complementary unit and a phase c bridge arm complementary unit. The DC bus voltage of the interleaved parallel converter is V dc , the phase current of the complementary unit of phase a bridge arm is ia , the phase current of the complementary unit of the b-phase bridge arm is i b , the phase current of the complementary unit of the c-phase bridge arm is i c . In this embodiment, if Figure 3 As shown, φ x The value range of Alien carriers can include Figure 3 C r1 and C r2 .

[0156] In one embodiment, please refer to the attached Figure 4 , attached Figure 4 is a waveform diagram for representing the changing relationship between the phase shift angle and the phase current according to an embodiment of the present application. Figure 4 As shown, the phase shift angle φ x With the phase current i of each phase bridge arm complementary unit x (Right now Figure 4 The phase current i x ), φ x The minimum and maximum values ​​of the phase current i x And, at the zero and peak of Figure 4 In the case of phase x, the bridge arm current i x1 and i x2 The minimum reverse current -I is achieved in the positive and negative half cycles respectively bs and I bs , so that the interleaved parallel converter can achieve full-range critical soft switching within the entire power frequency cycle.

[0157] In one implementation, constructing a heterogeneous carrier may specifically include steps S3041 to S3043:

[0158] Step S3041: Acquire a first forward sawtooth wave and a second forward sawtooth wave.

[0159] In this embodiment, C r1 Represents the first forward sawtooth wave, with C r2 represents the second forward sawtooth wave. The phase difference is φ x C r1 and C r2 When triggered at the beginning of the switching cycle, the interphase circulating current generated is always positive and cannot be reversed in polarity. Only half of the switch tubes can achieve soft switching. Therefore, it is necessary to set C r1 and C r2 Phase shifting is performed simultaneously.

[0160] Step S3042: Phase shift the first forward sawtooth wave and the second forward sawtooth wave by 0.5φ simultaneouslyx .

[0161] In this embodiment, according to the first forward sawtooth wave C r1 and the second forward sawtooth wave C r2 The generated irregular carrier generates the bridge arm current i x1 and i x2 The corresponding waveforms remain positive for different periods of time, i.e. x1 The holding time that remains positive during two switching cycles is not equal to i x1 The negative value is maintained during the holding time of two switching cycles. Therefore, a horizontal flip is required for the next switching cycle.

[0162] Step S3043: taking every two switching cycles as a group of switching cycles, horizontally flipping the first forward sawtooth wave and the second forward sawtooth wave of each group of switching cycles along the horizontal axis to obtain a final special-shaped carrier.

[0163] In one embodiment, please refer to the attached Figure 5 , attached Figure 5 FIG. 1 is a waveform diagram of a pulse signal obtained according to an embodiment of the present application based on a special-shaped carrier. Figure 5 As shown, according to the special-shaped carrier C r1 and C r2 Generate a pulse signal to control each switch device S of the bridge arm complementary unit x1 , S x2 , S' x1 and S' x2 .

[0164] In this embodiment, Figure 5 V x1 -V x2 Used to represent the complementary unit of the x-phase bridge arm, i x_dm Used to represent the interphase circulating current in the complementary unit of the x-phase bridge arm. V x_ref For the modulated wave.

[0165] In this embodiment, if Figure 5 As shown, the method of controlling the switch device may specifically include: r1 The amplitude is smaller than the modulation wave V x_ref When S x1 ; At carrier C r1 The amplitude is greater than or equal to the modulation wave V x_ref When S' is turned on x1 . In the carrier C r2 The amplitude is smaller than the modulation wave V x_ref When S x2 ; At carrier C r2 The amplitude is greater than or equal to the modulation wave V x_refWhen S' is turned on x2 .

[0004] Based on the method described in the above steps S101 to S103, the present application can determine the phase shift angle of the current cycle in real time according to the phase current value of the complementary unit of each phase bridge arm of the current switching cycle of the interleaved parallel converter and the DC bus voltage of the interleaved parallel converter, so as to use the dynamically updated phase shift angle to generate the interphase circulating current ripple that meets the critical soft switching condition, solve the problem of excessive zero-crossing harmonics in the traditional soft switching method, reduce the switching loss of the switching device, and greatly improve the state conversion efficiency of the switching device. In addition, the special-shaped carrier of the current switching cycle can be constructed by the phase shift angle, and the first carrier and the second carrier in the special-shaped carrier are used to generate the pulse signal of the first bridge arm and the second bridge arm to realize the current polarity reversal of the first bridge arm and the second bridge arm, and the soft switching of the converter can be realized without connecting an additional zero-crossing detection hardware circuit, thereby improving the power density and reducing the hardware cost.

[0166] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art can understand that in order to achieve the effect of the present application, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders. These adjusted schemes are equivalent to the technical schemes described in this application, and therefore will also fall within the scope of protection of this application.

[0167] It is understood by those skilled in the art that all or part of the processes in the method for implementing the above-mentioned embodiment of the present application can also be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium may include: any entity or device, medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal, telecommunication signal and software distribution medium, etc. that can carry the computer program code.

[0168] Another aspect of the present application also provides a computer-readable storage medium.

[0169] In an embodiment of a computer-readable storage medium according to the present application, the computer-readable storage medium may be configured to store a program for executing the soft switching implementation method of the converter of the above method embodiment, and the program may be loaded and run by the processor to implement the soft switching implementation method of the above converter. For ease of explanation, only the parts related to the embodiment of the present application are shown. For specific technical details not disclosed, please refer to the method part of the embodiment of the present application. The computer-readable storage medium may be a storage device formed by various electronic devices. Optionally, the computer-readable storage medium in the embodiment of the present application is a non-temporary computer-readable storage medium.

[0170] Another aspect of the present application also provides a controller.

[0171] In an embodiment of a controller according to the present application, the controller may include at least one processor; and a memory communicatively connected to the at least one processor; wherein a computer program is stored in the memory, and when the computer program is executed by the at least one processor, the method described in any of the above embodiments is implemented.

[0172] So far, the technical solution of the present application has been described in conjunction with an embodiment shown in the accompanying drawings, but it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present application.

Claims

1. A method for implementing soft switching of a converter, characterized in that: The method is applicable to an interleaved parallel converter, wherein the interleaved parallel converter comprises a three-phase bridge arm complementary unit, wherein each phase bridge arm complementary unit comprises a first bridge arm and a second bridge arm, wherein the first bridge arm and the second bridge arm are connected in parallel, and each of the bridge arms comprises a pair of complementary switch devices connected in series; the method comprises: Acquire the phase current value of the bridge arm complementary unit of each phase and the DC bus voltage of the staggered parallel converter in the current switching cycle; For each phase bridge arm complementary unit, determine the phase shift angle corresponding to each phase bridge arm complementary unit in the current switching cycle according to the phase current value and the DC bus voltage; According to the phase shift angle, a phase angle between a first carrier and a second carrier of the current switching cycle is obtained to form a special-shaped carrier, wherein the first carrier is a carrier for obtaining a pulse signal for controlling all switching devices on the first bridge arm, and the second carrier is a carrier for obtaining a pulse signal for controlling all switching devices on the second bridge arm; According to the special-shaped carrier, a pulse width modulation signal corresponding to each bridge arm is obtained to control the switching state of all switching devices on each bridge arm, thereby realizing soft switching of the staggered parallel converter.

2. The method for realizing soft switching of a converter according to claim 1, characterized in that: The step of acquiring the phase angle between the first carrier and the second carrier of the current switching cycle according to the phase shift angle to form a special-shaped carrier comprises: Acquire a first forward sawtooth wave and a second forward sawtooth wave, and set the phase angles of the first forward sawtooth wave and the second forward sawtooth wave to the phase shift angle, wherein the first forward sawtooth wave and the second forward sawtooth wave have the same shape and the same amplitude; At the start time of the current switching cycle, setting the initial positions of the first forward sawtooth wave and the second forward sawtooth wave according to half of the phase shift angle; Determining the first carrier and the second carrier according to the first forward sawtooth wave and the second forward sawtooth wave after the initial positions are set; The alien carrier is determined according to the first carrier and the second carrier.

3. The method for realizing soft switching of a converter according to claim 2, characterized in that: The determining the first carrier and the second carrier according to the first forward sawtooth wave and the second forward sawtooth wave after the initial position is set includes: Every two consecutive odd-numbered switching cycles and even-numbered switching cycles are regarded as a group of switching cycles; horizontally flipping the first forward sawtooth wave in the even-numbered switching cycles in each group of switching cycles to obtain the first carrier wave; The second forward sawtooth wave in the even-numbered switching cycles in each group of switching cycles is horizontally flipped to obtain the second carrier.

4. The method for realizing soft switching of a converter according to claim 1, characterized in that: The first bridge arm includes a first switch device and a second switch device connected in series with the first switch device, and the second bridge arm includes a third switch device and a fourth switch device connected in series with the third switch device; The step of obtaining a pulse width modulation signal corresponding to each bridge arm according to the heteromorphic carrier comprises: According to the comparison result of the first carrier and the modulated wave, a first pulse signal is obtained, and the switching states of the first switching device and the second switching device are determined according to the first pulse signal, wherein the first pulse signal is a pulse width modulation signal corresponding to the first bridge arm, and the modulated wave is a non-sinusoidal wave used to obtain a pulse width modulation signal in combination with the special-shaped carrier; According to the comparison result of the second carrier and the modulation wave, a second pulse signal is obtained, and the switching states of the third switching device and the fourth switching device are determined according to the second pulse signal, and the second pulse signal is a pulse width modulation signal corresponding to the second bridge arm.

5. The method for realizing soft switching of a converter according to claim 4, characterized in that: The step of obtaining a first pulse signal according to a comparison result between the first carrier wave and the modulated wave comprises: When the amplitude of the modulated wave is greater than or equal to the amplitude of the first carrier, the first pulse signal is determined to be at a high level; when the amplitude of the modulated wave is less than the amplitude of the first carrier, the first pulse signal is determined to be at a low level; The step of obtaining a second pulse signal according to a comparison result between the second carrier wave and the modulated wave comprises: When the amplitude of the modulated wave is greater than or equal to the amplitude of the second carrier, the second pulse signal is determined to be a high level; when the amplitude of the modulated wave is less than the amplitude of the second carrier, the second pulse signal is determined to be a low level.

6. The method for realizing soft switching of a converter according to claim 5, characterized in that: The first switching device is complementary to the second switching device, and the third switching device is complementary to the fourth switching device; The step of determining the switching states of the first switching device and the second switching device according to the first pulse signal comprises: If the first pulse signal is at a high level, it is determined that the switch state of the first switch device is an on state, and the switch state of the second switch device is an off state; If the first pulse signal is at a low level, it is determined that the switch state of the first switch device is an off state, and the switch state of the second switch device is an on state; The step of determining the switching states of the third switching device and the fourth switching device according to the second pulse signal comprises: If the second pulse signal is at a high level, it is determined that the switch state of the third switch device is an on state, and the switch state of the fourth switch device is an off state; If the second pulse signal is at a low level, it is determined that the switching state of the third switch device is an off state, and the switching state of the fourth switch device is an on state.

7. The method for realizing soft switching of a converter according to claim 1, characterized in that: The bridge arm complementary unit of each phase further comprises two auxiliary inductors connected in parallel, one end of each of the auxiliary inductors is respectively connected to a series connection point between two switch devices on one of the bridge arms, the other end of each of the auxiliary inductors is connected to the output side of the bridge arm complementary unit, and the inductance values ​​of the two auxiliary inductors are the same; The determining, according to the phase current value and the DC bus voltage, the phase shift angle corresponding to the bridge arm complementary unit of each phase of the current switching cycle comprises: The first quantitative relationship between the interphase circulating current ripple, the phase shift angle and the DC bus voltage is determined according to the following formula: in, is the phase shift angle, V dc is the DC bus voltage, T s is the length of the current switching cycle, ΔI rp is the interphase circulating current ripple flowing through the auxiliary inductor, L m is the inductance value of the auxiliary inductor; Based on the critical soft switching condition, a second quantitative relationship between the interphase circulating current ripple and the phase current value is determined according to the following formula: Among them, i x is the phase current value, I bs The current value of the bias current of each of the switching devices, ΔI rp is the interphase circulating current ripple flowing through the auxiliary inductor; The phase shift angle is obtained according to the first quantitative relationship and the second quantitative relationship.

8. The method for realizing soft switching of a converter according to claim 7, characterized in that: The obtaining the phase shift angle according to the first quantitative relationship and the second quantitative relationship comprises: According to the modulation wave, the value range of the phase shift angle is determined according to the following formula: Among them, V ref The amplitude of the modulated wave of the pulse width modulation signal is obtained by comparing it with the amplitude of the shaped carrier wave. is the phase shift angle; According to the first quantitative relationship and the second quantitative relationship, the following formula is determined to obtain the phase shift angle: in, is the phase shift angle, V dc is the DC bus voltage, T s is the length of the current switching cycle, i x is the phase current value, I bs The current value of the bias current for each of the switching devices, L m is an inductance value of the auxiliary inductor.

9. A controller, characterized in that: include: at least one processor; and, a memory communicatively coupled to the at least one processor; The memory stores a computer program, and when the computer program is executed by the at least one processor, the soft switching implementation method of the converter according to any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium storing a plurality of program codes, characterized in that: The program code is suitable for being loaded and run by a processor to execute the soft switching implementation method of the converter according to any one of claims 1 to 8.

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