Method for driving a three-phase inverter half-bridge

Abstract

The application relates to a driving method of a three-phase conversion half bridge. The method comprises the following steps: driving the three-phase conversion half bridge by a first commutation strategy; acquiring a first detection voltage, a second detection voltage and a third detection voltage of three bridge arms in the three-phase conversion half bridge; the first detection voltage is greater than the second detection voltage, and the second detection voltage is greater than the third detection voltage; when the first detection voltage, the second detection voltage and the third detection voltage meet a preset condition, driving the three-phase conversion half bridge by a first driving strategy in a corresponding switching cycle, so that the three bridge arms of the three-phase conversion half bridge are normally commutated. By driving the three-phase conversion half bridge by the first driving strategy when the first detection voltage, the second detection voltage and the third detection voltage meet the preset condition, the capacitor of the two bridge arms is prevented from being short-circuited, and the three-phase conversion half bridge is further enabled to stably output current.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a driving method for a three-phase conversion half-bridge. Background Technology

[0002] A single-stage three-phase resonant DC / AC converter is a power electronic device that integrates DC-AC conversion, electrical isolation, and resonant soft-switching technology into a single power stage. Compared to the traditional two-stage structure, it has the advantages of lower cost and higher efficiency. The AC side of the single-stage three-phase resonant DC / AC converter uses a half-bridge frequency conversion structure, which is implemented through two switching transistors. A total of three half-bridge frequency conversion structures are used across the three phases, hence the name "three-phase conversion half-bridge."

[0003] The three-phase converter half-bridge achieves three-phase current output by setting up three half-bridge cycle conversion structures with a total of six switching transistors. In current related technologies, when the voltages of the two bridge arms are similar, due to noise and measurement errors, the measured voltages of the two bridge arms may be misjudged. At this time, the traditional driving strategy will cause the capacitors of the two bridge arms to short-circuit, thereby affecting the output current of the three-phase converter half-bridge. Summary of the Invention

[0004] Therefore, it is necessary to provide a driving method for a three-phase conversion half-bridge to address the aforementioned technical problems.

[0005] In a first aspect, this application provides a driving method for a three-phase converter half-bridge. The three-phase converter half-bridge includes three bridge arms, and the upper bridge arm of each bridge arm includes two series-connected switching transistors. The method includes: driving the three-phase converter half-bridge with a first commutation strategy; acquiring a first detection voltage, a second detection voltage, and a third detection voltage of the three bridge arms of the three-phase converter half-bridge; wherein the first detection voltage is greater than the second detection voltage, and the second detection voltage is greater than the third detection voltage; when the first detection voltage, the second detection voltage, and the third detection voltage meet preset conditions, driving the three-phase converter half-bridge with the first driving strategy in the corresponding switching cycle, so that the three bridge arms of the three-phase converter half-bridge can be commutated normally; wherein, the first detection voltage, the second detection voltage, and the third detection voltage meeting preset conditions includes: the difference between the first detection voltage and the second detection voltage is less than a preset threshold, or the difference between the second detection voltage and the third detection voltage is less than a preset threshold; wherein, the first driving strategy is determined based on the first commutation strategy and the bridge arms corresponding to the two detection voltages that meet the preset conditions.

[0006] In one embodiment, the lower arm of each arm of the three-phase conversion half-bridge includes a capacitor; the method further includes: using the arm corresponding to the first detection voltage as the first phase arm, the arm corresponding to the second detection voltage as the second phase arm, and the arm corresponding to the third detection voltage as the third phase arm; the upper arm of the first phase arm includes a first switch and a second switch connected in series; the upper arm of the second phase arm includes a third switch and a fourth switch connected in series, and the upper arm of the third phase arm includes a fifth switch and a sixth switch connected in series.

[0007] In one embodiment, the step of driving the three-phase converter half-bridge with a first driving strategy in the corresponding switching cycle when the first detection voltage, the second detection voltage, and the third detection voltage meet preset conditions, so that the three arms of the three-phase converter half-bridge can be normally commutated, includes: when the difference between the second detection voltage and the third detection voltage is less than a preset threshold, driving the three-phase converter half-bridge with a first target driving strategy in the corresponding switching cycle, so that at least some of the switches corresponding to the three arms of the three-phase converter half-bridge are turned on with zero voltage; and / or when the difference between the first detection voltage and the second detection voltage is less than a preset threshold, driving the three-phase converter half-bridge with a second target driving strategy in the corresponding switching cycle, so that at least some of the switches corresponding to the three arms of the three-phase converter half-bridge are turned on with zero voltage.

[0008] In one embodiment, the first target driving strategy includes: the third switch and the sixth switch are turned on alternately, and the fourth switch and the fifth switch are turned on alternately.

[0009] In one embodiment, the step of driving the three-phase converter half-bridge with a first target driving strategy in the corresponding switching cycle when the difference between the second and third detected voltages is less than a preset threshold, so that at least some of the switches corresponding to the three arms of the three-phase converter half-bridge are turned on with zero voltage, includes: when the difference between the second and third detected voltages is less than a preset threshold, if the first commutation strategy is an LMS driving strategy at this time, then the first target driving strategy is a first LMS target driving strategy; driving the three-phase converter half-bridge with the first LMS target driving strategy in the corresponding switching cycle, so that the second, third, fourth, and fifth switches are turned on with zero voltage; and when the second actual voltage is less than a preset threshold, the step of driving the three-phase converter half-bridge with a first LMS target driving strategy in the corresponding switching cycle, so that the second, third, fourth, and fifth switches are turned on with zero voltage; and ... The sixth switch will not short-circuit when the third actual voltage is present, and the sixth switch will turn on with zero voltage when the second actual voltage is greater than the third actual voltage. When the difference between the second and third detection voltages is less than a preset threshold, if the first commutation strategy is an LSM drive strategy, then the first target drive strategy is the first LSM target drive strategy. The three-phase conversion half-bridge is driven with the first LSM target drive strategy in the corresponding switching cycle to turn on the second, fourth, fifth, and sixth switches with zero voltage. The third switch will not short-circuit when the second actual voltage is less than the third actual voltage, and the third switch will turn on with zero voltage when the second actual voltage is greater than the third actual voltage.

[0010] In one embodiment, the first LMS target driving strategy includes: the first switch is continuously turned on during the switching cycle; during the switching cycle, the second switch is turned off at a first moment, the sixth switch is turned off at a second moment, and the third switch is turned on at a third moment; after the conduction duration of the second phase bridge arm, the third switch is turned off at a fourth moment, the sixth switch is turned on at a fifth moment, the fourth switch is turned off at a sixth moment, and the fifth switch is turned on at a seventh moment; after the conduction duration of the third phase bridge arm, the fifth switch is turned off at an eighth moment, the second and fourth switches are turned on at a ninth moment, and the switching cycle ends after the conduction duration of the first phase bridge arm.

[0011] In one embodiment, the first LSM target driving strategy includes: the first switch being continuously turned on during the switching cycle; during the switching cycle, the second switch being turned off at a first moment, the fourth switch being turned off at a second moment, and the fifth switch being turned on at a third moment; after the duration of the third phase bridge arm being turned on, the sixth switch being turned off at a fourth moment, the third switch being turned on at a fifth moment, the fifth switch being turned off at a sixth moment, and the fourth switch being turned on at a seventh moment; after the duration of the second phase bridge arm being turned on, the third switch being turned off at an eighth moment, and the second and sixth switches being turned on at a ninth moment, and the switching cycle ending after the duration of the first phase bridge arm being turned on.

[0012] In one embodiment, the second target driving strategy includes: the first switch and the fourth switch are turned on alternately, and the second switch and the third switch are turned on alternately.

[0013] In one embodiment, the step of driving the three-phase converter half-bridge with a second target driving strategy in the corresponding switching cycle when the difference between the first and second detected voltages is less than a preset threshold, so that at least some of the switches corresponding to the three arms of the three-phase converter half-bridge are turned on with zero voltage, includes: when the difference between the first and second detected voltages is less than a preset threshold, if the first commutation strategy is an LMS driving strategy, then the second target driving strategy is a second LMS target driving strategy; driving the three-phase converter half-bridge with the second LMS target driving strategy in the corresponding switching cycle, so that the first, second, third, and fifth switches are turned on with zero voltage; and when the first actual voltage is less than a preset threshold, the step of driving the three-phase converter half-bridge with a second LMS target driving strategy in the corresponding switching cycle, so that the first switch, second switch, third switch, and fifth switch are turned on with zero voltage; and ... at least some of the switches corresponding to the three arms of the three-phase converter half-bridge are turned on with zero voltage; and driving the three-phase converter half-bridge with The fourth switch will not short-circuit when the second actual voltage is present, and the fourth switch will turn on with zero voltage when the first actual voltage is greater than the second actual voltage. When the difference between the first and second detection voltages is less than a preset threshold, if the first commutation strategy is an LSM drive strategy, then the second target drive strategy is a second LSM target drive strategy. The three-phase conversion half-bridge is driven with the second LSM target drive strategy in the corresponding switching cycle to turn on the second, third, fourth, and fifth switches with zero voltage. The first switch will not short-circuit when the first actual voltage is less than the second actual voltage, and the first switch will turn on with zero voltage when the first actual voltage is greater than the second actual voltage.

[0014] In one embodiment, the second LMS target driving strategy includes: the sixth switch being continuously turned on during the switching cycle; during the switching cycle, the fifth switch is turned off at a first moment, the third switch is turned off at a second moment, and the second switch is turned on at a third moment; after the duration of the first phase bridge arm being turned on, the first switch is turned off at a fourth moment, the fourth switch is turned on at a fifth moment, the second switch is turned off at a sixth moment, and the third switch is turned on at a seventh moment; after the duration of the second phase bridge arm being turned on, the fourth switch is turned off at an eighth moment, and the fifth switch and the first switch are turned on at a ninth moment, and the switching cycle ends after the duration of the third phase bridge arm being turned on.

[0015] In one embodiment, the second LSM target driving strategy includes: the sixth switch being continuously turned on during the switching cycle; during the switching cycle, the fifth switch is turned off at a first moment, the first switch is turned off at a second moment, and the fourth switch is turned on at a third moment; after the duration of the second phase bridge arm's conduction, the fourth switch is turned off at a fourth moment, the first switch is turned on at a fifth moment, the third switch is turned off at a sixth moment, and the second switch is turned on at a seventh moment; after the duration of the first phase bridge arm's conduction, the second switch is turned off at an eighth moment, and the third and fifth switches are turned on at a ninth moment, and the switching cycle ends after the duration of the third phase bridge arm's conduction.

[0016] The aforementioned driving method for the three-phase converter half-bridge first employs a first commutation strategy to drive the three-phase converter half-bridge. During the operation of the three-phase converter half-bridge, the first detection voltage, second detection voltage, and third detection voltage of the three arms of the three-phase converter half-bridge are acquired. The first detection voltage is greater than the second detection voltage, and the second detection voltage is greater than the third detection voltage. When the first, second, and third detection voltages meet preset conditions, the three-phase converter half-bridge is driven using the first driving strategy in the corresponding switching cycle to ensure normal commutation. By driving the three-phase converter half-bridge using the first driving strategy when the first, second, and third detection voltages meet preset conditions, short circuits in the capacitors of the two arms are avoided, further stabilizing the output current of the three-phase converter half-bridge. Attached Figure Description

[0017] Figure 1 This is a circuit diagram of a three-phase converter half-bridge in one embodiment;

[0018] Figure 2 This is a flowchart illustrating a driving method for a three-phase conversion half-bridge in one embodiment;

[0019] Figure 3 This is a schematic diagram of the driving signals for the first LMS target driving strategy in one embodiment;

[0020] Figure 4 This is the equivalent circuit corresponding to the commutation process of the L-phase bridge arm and the M-phase bridge arm in one embodiment.

[0021] Figure 5 This is the equivalent circuit corresponding to the commutation process of the M-phase bridge arm and the S-phase bridge arm in one embodiment.

[0022] Figure 6 This is the equivalent circuit corresponding to the commutation process of the S-phase bridge arm and the L-phase bridge arm in one embodiment.

[0023] Figure 7 This is a schematic diagram of the driving signals for the first LSM target driving strategy in one embodiment;

[0024] Figure 8 This is a schematic diagram of the driving signals for the second LMS target driving strategy in one embodiment;

[0025] Figure 9 This is a schematic diagram of the driving signals for the second LSM target driving strategy in one embodiment. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] A single-stage three-phase resonant DC / AC converter is a power electronic device that integrates DC-AC conversion, electrical isolation, and resonant soft-switching technology into a single power stage. Compared to the traditional two-stage structure, it has the advantages of lower cost and higher efficiency. The AC side of the single-stage three-phase resonant DC / AC converter uses a half-bridge frequency conversion structure, which is implemented through two switching transistors. A total of three half-bridge frequency conversion structures are used across the three phases, hence the name "three-phase conversion half-bridge."

[0028] like Figure 1 As shown, a three-phase converter half-bridge is provided, wherein an LC resonant circuit is connected to the input terminal of the three-phase converter half-bridge, and the three-phase voltage V is output through the three-phase converter half-bridge. L V M and V S In this three-bridge configuration, each bridge arm includes a bidirectional switch and a capacitor. Each bridge arm's output terminal is equipped with a filter circuit, which can be an LC filter, an inductor-based filter, etc. This embodiment does not limit the specific configuration of the filter circuit, as long as it achieves the filtering function. The bidirectional switch includes two transistors with diodes in different directions. Three-phase current output is achieved through the alternating conduction of six transistors across the three bridge arms. In current related technologies, soft switching of all transistors can theoretically be achieved using resonant elements. However, when the voltages of two bridge arms are similar, noise and measurement errors can lead to misjudgments of the measured voltages. In this case, traditional driving strategies can cause short circuits in the capacitors of the two bridge arms, affecting the output current of the three-phase converter half-bridge. Furthermore, how the transistors achieve soft switching in this region when misjudgments occur is unknown.

[0029] In one embodiment, such as Figure 2 As shown, a driving method for a three-phase converter half-bridge is provided, which is used to control... Figure 1The diagram shows a three-phase converter half-bridge. The three-phase converter half-bridge includes three arms, and the upper arm of each arm includes a bidirectional switch, that is, two switches connected in series. The following steps are described:

[0030] Step 201: Drive the three-phase converter half-bridge with the first commutation strategy.

[0031] A three-phase converter half-bridge is a power electronic topology consisting of three bridge arms. It is used to convert AC input to three-phase AC voltage via high-frequency resonance. Each bridge arm contains a bidirectional switch and a capacitor, and can be used to achieve direct AC to three-phase AC conversion. Figure 1 As shown, the three-phase converter half-bridge connects three bridge arms via the secondary side of a transformer to form a three-phase output structure. The current direction switching and energy transfer of each bridge arm are controlled by the on / off switching of switching transistors. During operation, the three-phase converter half-bridge is initially driven by a first commutation strategy. This first commutation strategy is a pre-set standard switching timing control logic for the six switching transistors in the three bridge arms. It indicates the conduction sequence and phase relationship of the six switching transistors under normal operating conditions, controlling the commutation of the three-phase converter half-bridge under normal operating conditions and outputting a sinusoidal waveform. When driving the three-phase converter half-bridge with the first commutation strategy, drive signals are sent to the six switching transistors according to the preset standard switching timing control logic, thus enabling the three-phase converter half-bridge to operate in standard mode.

[0032] Step 202: Obtain the first detection voltage, the second detection voltage, and the third detection voltage of the three arms of the three-phase conversion half-bridge.

[0033] During the operation of the three-phase converter half-bridge, the voltage of each arm in the three-phase converter half-bridge is acquired in real time. It is understood that the voltage of each arm can be acquired through voltage sensors or voltage sampling circuits, etc. This embodiment does not impose specific limitations, as long as the corresponding voltage can be acquired. After acquiring the voltage of each arm, the voltages of each arm are sorted according to their magnitude. The voltage of an arm can be the voltage across the corresponding arm capacitor or the voltage at the corresponding arm output terminal. Regarding the voltage at the arm output terminal, when a filter is provided at the output terminal of the arm, the voltage at the output terminal can be either the voltage before or after the filter. When no filter is provided at the output terminal of the arm, the voltage at the output terminal is simply the voltage at the arm output terminal. The voltage with the largest magnitude is the first detection voltage, the voltage with the smallest magnitude is the third detection voltage, and the voltage with an intermediate value is the second detection voltage. That is, the first detection voltage is greater than the second detection voltage, and the second detection voltage is greater than the third detection voltage. The voltage of each bridge arm is sorted by magnitude, including polarity, for example, -1V is greater than -2V; 3V is greater than -1V.

[0034] Step 203: When the first detection voltage, the second detection voltage, and the third detection voltage meet the preset conditions, the three-phase conversion half-bridge is driven by the first driving strategy in the corresponding switching cycle so that the three arms of the three-phase conversion half-bridge can be commutated normally.

[0035] After determining the first, second, and third detection voltages, it is judged whether the first, second, and third detection voltages meet preset conditions. The preset conditions are the logical judgment criteria for triggering the first driving strategy. By using the preset conditions, risk areas that may be misjudged due to noise can be identified, and the three-phase converter half-bridge can be driven in these areas through the first driving strategy to ensure commutation safety.

[0036] The preset conditions for the first, second, and third detection voltages to meet include: the difference between the first and second detection voltages being less than a preset threshold, or the difference between the second and third detection voltages being less than a preset threshold. Specifically, the absolute value of the first difference between the first and second detection voltages is calculated. When the absolute value of the first difference is less than the preset threshold, the preset condition is met. The absolute value of the second difference between the second and third detection voltages is calculated. When the absolute value of the second difference is less than the preset threshold, the preset condition is met. The preset threshold can be set according to actual usage requirements; this embodiment does not impose specific limitations. Meeting the preset conditions indicates that the first and second detection voltages are close, or the second and third detection voltages are close. In this case, voltage misjudgment of the two bridge arms may occur, leading to a short circuit in the capacitors of the two bridge arms with similar voltages. Therefore, when the preset conditions are met, the three-phase converter half-bridge needs to be driven by the first driving strategy to ensure commutation safety.

[0037] When the first, second, and third detection voltages meet preset conditions, the three-phase conversion half-bridge is driven using a first driving strategy during the corresponding switching cycle to ensure normal commutation of the three arms. The switching cycle represents the time required for each pair of the three arms to complete one commutation cycle and for all six corresponding switches to complete one on / off cycle. The first driving strategy is a switching timing scheme that avoids voltage misjudgment between two arms, preventing short circuits caused by capacitors in arms with similar voltages. Specifically, the first driving strategy is determined based on the first commutation strategy and the arms corresponding to the two detection voltages that meet the preset conditions. While retaining the commutation logic framework of the first commutation strategy, the switching timing of the switches is adjusted for the two arms with similar detection voltages to generate the first driving strategy. For example, if the first commutation strategy is replaced by the LMS driving strategy, and the first and second detection voltages meet the preset conditions, the switching timing of the corresponding arms is adjusted based on the LMS driving strategy to obtain the first driving strategy.

[0038] Specifically, after determining the first detection voltage, the second detection voltage, and the third detection voltage, the system switches to the first driving strategy in the current switching cycle and drives one or more switching cycles with the first driving strategy.

[0039] This embodiment first drives the three-phase converter half-bridge using a first commutation strategy. During the operation of the three-phase converter half-bridge, the first, second, and third detection voltages of the three arms of the three-phase converter half-bridge are acquired. The first detection voltage is greater than the second detection voltage, and the second detection voltage is greater than the third detection voltage. When the first, second, and third detection voltages meet preset conditions, the three-phase converter half-bridge is driven using the first driving strategy in the current switching cycle to ensure normal commutation. The current switching cycle is the next driving cycle of the three-phase converter half-bridge after acquiring the first, second, and third detection voltages. By driving the three-phase converter half-bridge using the first driving strategy when the first, second, and third detection voltages meet preset conditions, short circuits in the capacitors of the two arms are avoided, further stabilizing the output current of the three-phase converter half-bridge.

[0040] In one embodiment, after acquiring the first, second, and third detection voltages, the bridge arm corresponding to the first detection voltage is designated as the first phase bridge arm, the bridge arm corresponding to the second detection voltage is designated as the second phase bridge arm, and the bridge arm corresponding to the third detection voltage is designated as the third phase bridge arm. Specifically, the bridge arm corresponding to the first detection voltage with the largest magnitude is designated as the first phase bridge arm, i.e., the L-phase bridge arm; the bridge arm corresponding to the third detection voltage with the smallest magnitude is designated as the third phase bridge arm, i.e., the S-phase bridge arm; and the bridge arm corresponding to the second detection voltage with a magnitude in the middle is designated as the second phase bridge arm, i.e., the M-phase bridge arm. It is understandable that, during the operation of the three-phase converter half-bridge, it is necessary to acquire the voltage of each bridge arm in the three-phase converter half-bridge in real time. Therefore, the first, second, and third phase bridge arms need to be determined in real time based on the acquired voltage magnitudes.

[0041] The lower arm of each arm of the three-phase converter half-bridge includes a capacitor. Specifically, the upper arm of the first phase arm includes a first switch and a second switch connected in series, and the lower arm of the first phase arm includes a first capacitor. The upper arm of the second phase arm includes a third switch and a fourth switch connected in series, and the lower arm of the second phase arm includes a second capacitor. The upper arm of the third phase arm includes a fifth switch and a sixth switch connected in series, and the lower arm of the third phase arm includes a third capacitor.

[0042] Specifically, such as Figure 1 As shown, in the three arms of the three-phase converter half-bridge, each arm consists of a bidirectional switch and a capacitor. Based on the real-time voltage relationship of the capacitor, the first detected voltage with the largest magnitude is denoted as V. L The capacitance of the corresponding bridge arm is denoted as C. L In a bidirectional switch corresponding to a bridge arm, the first switch is denoted as S. L1 The second switch is denoted as S. L2 The corresponding bridge arm is denoted as the L-phase bridge arm; the second detection voltage, whose voltage magnitude is in the middle, is denoted as V. M The capacitance of the corresponding bridge arm is denoted as C. M In a bidirectional switch corresponding to a bridge arm, the third switch is denoted as S. M1 The fourth switch is denoted as S. M2 The corresponding bridge arm is denoted as the M-phase bridge arm; the third detection voltage with the smallest voltage magnitude is denoted as V. S The capacitance of the corresponding bridge arm is denoted as C. S In a bidirectional switch corresponding to a bridge arm, the fifth switch is denoted as S. S1 The sixth switch is denoted as S. S2 The corresponding bridge arm is denoted as the S-phase bridge arm.

[0043] When the three-phase converter half-bridge is driven with the first commutation strategy, since the first detection voltage is greater than the second detection voltage, and the second detection voltage is greater than the third detection voltage, the first switching transistor S of the L-phase bridge arm can be set. L1 In the normally on state, the sixth switch S of the S-phase bridge arm S2 It is in the normally on state. Simultaneously, when both switches in the L-phase bridge arm are on, the fourth switch S in the M-phase bridge arm... M2 The diode can remain on continuously. This is because the first detection voltage of the L-phase bridge arm is greater than the second detection voltage of the M-phase bridge arm, and the fourth switch S... M2 When turned on, the third switch S M1 It is in the off state, and the third switch S M1 The capacitor is in the off state, therefore, the fourth switch S is set. M2 The switch in phase L remains on when it is turned on. Similarly, when both switches in phase S are on, the third switch in phase M remains on. M1 The diode can conduct continuously; therefore, a third switch S is set. M1 The switch in the S-phase bridge arm remains on when it is turned on.

[0044] In one embodiment, since the preset conditions include two cases, when the first detection voltage, the second detection voltage, and the third detection voltage meet the preset conditions, the three-phase conversion half-bridge is driven by the first driving strategy in the corresponding switching cycle so that the three arms of the three-phase conversion half-bridge can be normally commutated. This also includes two cases.

[0045] In the first case, when the difference between the second detection voltage and the third detection voltage is less than a preset threshold, the three-phase conversion half-bridge is driven by the first target driving strategy in the corresponding switching cycle, so that at least some of the switching transistors corresponding to the three arms of the three-phase conversion half-bridge are turned on with zero voltage.

[0046] The first scenario concerns the second detection voltage V. M With the third detection voltage V SIn the case of near-close proximity, i.e., when the voltages of the M-phase bridge arm and the S-phase bridge arm are close, the three-phase conversion half-bridge is driven using the first target driving strategy during the corresponding switching cycle. The first target driving strategy is a timing scheme for driving the switching transistors when the second and third detection voltages are close. This strategy can suppress the risk of short circuits in the two bridge arms due to voltage misjudgment when the second and third detection voltages are close, ensuring normal commutation of the three bridge arms of the three-phase conversion half-bridge. Zero-voltage turn-on of the switching transistors refers to the process where the drain-source voltage of the switching transistor has dropped to zero or near zero before the gate signal is applied. Zero-voltage turn-on eliminates voltage and current overlap during the switching process, reduces turn-on losses, and minimizes electromagnetic interference. The first target driving strategy enables partial or complete zero-voltage turn-on of the six switching transistors in the three bridge arms.

[0047] In one embodiment, the first target driving strategy includes: the third switch and the sixth switch are alternately turned on, and the fourth switch and the fifth switch are alternately turned on. When using the first target driving strategy to drive the three-phase converter half-bridge, the third switch S of the M-phase bridge arm... M1 The sixth switch S of the S-phase bridge arm S2 The circuit alternates between phases; the fourth switch S of the M-phase bridge arm... M2 The fifth switch S of the S-phase bridge arm S1 The two switches conduct alternately. Alternating conduction means that the two switches are turned on in a time-sharing manner, and their conduction times do not overlap. By alternating conduction, short circuits between the two phase capacitors can be avoided.

[0048] In the second scenario, when the difference between the first and second detection voltages is less than a preset threshold, the three-phase conversion half-bridge is driven by the second target driving strategy during the corresponding switching cycle, so that at least some of the switching transistors corresponding to the three arms of the three-phase conversion half-bridge are turned on with zero voltage.

[0049] The second scenario concerns the first detection voltage V. L Second detection voltage V M When the voltages are close, specifically when the voltages of the L-phase bridge arm and the M-phase bridge arm are similar, the three-phase converter half-bridge is driven using a second target driving strategy during the corresponding switching cycle. This second target driving strategy is a timing scheme for driving the switching transistors when the first and second detected voltages are close. This strategy can suppress the risk of short circuits in the two bridge arms due to voltage misjudgment when the first and second detected voltages are close, ensuring normal commutation of the three bridge arms. The second target driving strategy enables some or all of the six switching transistors in the three bridge arms to be turned on with zero voltage.

[0050] In one embodiment, the second target driving strategy includes: the first switch and the fourth switch are alternately turned on, and the second switch and the third switch are alternately turned on. When using the second target driving strategy to drive the three-phase converter half-bridge, the first switch S of the L-phase bridge arm... L1 The fourth switch S of the M-phase bridge arm M2 The two phases alternately conduct; the second switch S of the L-phase bridge arm L2 The third switch S of the M-phase bridge arm M1 The two switches conduct alternately. Alternating conduction means that the two switches are turned on in a time-sharing manner, and their conduction times do not overlap. By alternating conduction, short circuits between the two phase capacitors can be avoided.

[0051] In the first case, when the difference between the second and third detected voltages is less than a preset threshold, that is, when the voltages of the M-phase bridge arm and the S-phase bridge arm are close, if the first commutation strategy is driven by the LMS drive strategy, then the first target drive strategy is the first LMS target drive strategy; the three-phase conversion half-bridge is driven by the first LMS target drive strategy in the corresponding switching cycle, so that the second, third, fourth, and fifth switches are turned on with zero voltage; and the sixth switch will not short-circuit when the second actual voltage is less than the third actual voltage, and the sixth switch is turned on with zero voltage when the second actual voltage is greater than the third actual voltage.

[0052] The first commutation strategy can include an LMS driving strategy and an LSM driving strategy. The LMS driving strategy means that when driving the three-phase converter half-bridge using the LMS driving strategy, commutation is performed in the order of L-phase bridge arm, M-phase bridge arm, and S-phase bridge arm. The LSM driving strategy means that when driving the three-phase converter half-bridge using the LSM driving strategy, commutation is performed in the order of L-phase bridge arm, S-phase bridge arm, and M-phase bridge arm. When the first commutation strategy is the LMS driving strategy, the first target driving strategy is the first LMS target driving strategy. That is, the commutation order of the three bridge arms corresponding to the first target driving strategy and the first commutation strategy remains unchanged, but the conduction timing of the switching transistors is changed. The actual voltage is the real voltage in each bridge arm during the operation of the three-phase converter half-bridge. The second actual voltage is the real voltage of the M-phase bridge arm during the operation of the three-phase converter half-bridge. The third actual voltage is the real voltage of the S-phase bridge arm during the operation of the three-phase converter half-bridge. When driving the three-phase converter half-bridge using the first LMS target driving strategy, the second switching transistor S... L2 Third switch S M1 Fourth switch S M2 and the fifth switch S S1 Zero-voltage turn-on, the sixth switch S when the second actual voltage is less than the third actual voltage S2 Hard turn-on, the sixth switch S when the second actual voltage is greater than the third actual voltageS2 Zero voltage start-up.

[0053] The first LMS target driving strategy includes: the first switch is continuously turned on during the switching cycle; during the switching cycle, the second switch is turned off at the first moment, the sixth switch is turned off at the second moment, and the third switch is turned on at the third moment; after the conduction duration of the second phase bridge arm, the third switch is turned off at the fourth moment, the sixth switch is turned on at the fifth moment, the fourth switch is turned off at the sixth moment, and the fifth switch is turned on at the seventh moment; after the conduction duration of the third phase bridge arm, the fifth switch is turned off at the eighth moment, the second and fourth switches are turned on at the ninth moment, and the switching cycle ends after the conduction duration of the first phase bridge arm.

[0054] Specifically, such as Figure 3 As shown, during the entire switching cycle of the first LMS target-driven strategy, the first switching transistor S... L1 It remains connected.

[0055] During the commutation process of the L-phase bridge arm and the M-phase bridge arm, the second switch S L2 At the first moment t1, the sixth switch S is turned off. S2 The third switch S is turned off at the second time t2. M1 At the third moment t3, the circuit is turned on. If there is no misjudgment of the capacitor voltage, that is, the second actual voltage is greater than the third actual voltage, then when the second switch S... L2 After being turned off, the third switch S M1 First, it is discharged to zero. At this time, the fifth switch S S1 The remaining voltage is the second actual voltage minus the third actual voltage. Since the M-phase bridge arm is already conducting, the sixth switch S is turned off at the second time t2. S2 Its voltage will remain zero. Therefore, at the third time t3, the third switch S... M1 The circuit is switched on at zero voltage. If a misjudgment occurs regarding the capacitor voltage, i.e., the second actual voltage is less than the third actual voltage, then at the first moment t1, the fifth switch S... S1 It will be discharged to zero first. At this time, the third switch S M1 The remaining voltage is the third actual voltage minus the second actual voltage. At the second time t2, the sixth switch S is turned off. S2 The sixth switch S S2 The parallel capacitor is charged, and the third switch S M1 The parallel capacitor continues to discharge until it reaches zero. Therefore, at the third time t3, the third switch S... M1 It turns on at zero voltage. Therefore, during the commutation process of the L-phase bridge arm and the M-phase bridge arm, regardless of whether there is a misjudgment of the relationship between the second and third actual voltages, the third switch S... M1 Both can achieve zero-voltage start-up.

[0056] like Figure 4 As shown, an equivalent circuit corresponding to the commutation process of the L-phase bridge arm and the M-phase bridge arm during the first LMS target driving strategy is provided. During the commutation of the L-phase bridge arm and the M-phase bridge arm, the first switch S is initially in the following state... L1 Second switch S L2 Fourth switch S M2 and the sixth switch S S2 Turn on. First, turn off the second switch S. L2 Since the resonant current is less than zero, the second switch S L2 The parallel capacitor is charged, and the third switch S M1 and the fifth switch S S1 The parallel capacitor is discharged. If the second actual voltage is greater than the third actual voltage, then the third switch S... M1 First, it is discharged to zero. At this time, the fifth switch S S1 The remaining voltage is the second actual voltage minus the third actual voltage; the sixth switch S remains off. S2 Since the M-phase bridge arm is already conducting, the sixth switch S... S2 The voltage will remain zero. Therefore, the third switch S M1 It turns on at zero voltage. If the second actual voltage is less than the third actual voltage, then the fifth switch S... S1 It will be discharged to zero first, then the third switch S M1 The remaining voltage is the third actual voltage minus the second actual voltage. Then, the sixth switch S is turned off. S2 The second switch S L2 and the sixth switch S S2 The parallel capacitor is charged, and the third switch S M1 The parallel capacitor is discharged until it reaches zero. Then the third switch S is turned on. M1 It turns on at zero voltage. Therefore, during the commutation process of the L-phase bridge arm and the M-phase bridge arm, regardless of whether there is a misjudgment of the relationship between the second and third actual voltages, the third switch S... M1 Both can achieve zero-voltage start-up.

[0057] During the commutation process of the M-phase bridge arm and the S-phase bridge arm, at the fourth time t4, the third switch S... M1 First, turn off the sixth switch S at time t5. S2 The fourth switch S is turned on at time t6. M2 Turn off at time t7, the fifth switch S S1 The circuit is turned on. At the fourth moment t4, the third switch S is turned off. M1 At this time, the resonant current is less than zero, and the current flows from the third switch S. M1The diode continues to conduct electricity, without affecting other parts of the circuit. If there is no misjudgment of the capacitor voltage, meaning the second actual voltage is greater than the third actual voltage, then due to the sixth switch S... S2 Since the voltage is always zero, it can be approximated that it turns on with zero voltage at the fifth time t5 and turns off the fourth switch S at the sixth time t6. M2 Under negative resonant current, the second switch S L2 and the fourth switch S M2 The capacitor will be charged, and the fifth switch S S1 The capacitor will be discharged to zero at time t7, when the fifth switch S... S1 Achieving zero-voltage turn-on. If a misjudgment occurs in the capacitor voltage, i.e., the second actual voltage is less than the third actual voltage, the sixth switch S... S2 At the fifth moment, t5 will hard-conduct, and the third switch S... M1 The diode is turned off. At time t6, the fourth switch S... M2 Turn off, fourth switch S M2 The voltage will remain zero. When the fifth switch S... S1 The conduction signal is activated at zero voltage when the seventh time t7 arrives. Therefore, during the commutation process of the M-phase bridge arm and the S-phase bridge arm, the fifth switch S... S1 Zero-voltage turn-on can be achieved. The sixth switch, S... S2 Zero-voltage turn-on occurs when the second actual voltage is greater than the third actual voltage, and hard-conducting occurs when the second actual voltage is less than the third actual voltage. During hard-conducting, the voltage is very small, and the conduction voltage is the third actual voltage minus the second actual voltage.

[0058] like Figure 5 As shown, an equivalent circuit corresponding to the commutation process of the M-phase bridge arm and the S-phase bridge arm during the first LMS target driving strategy is provided. During the commutation of the M-phase bridge arm and the S-phase bridge arm, the first switch S is initially in the following state... L1 Third switch S M1 and the fourth switch S M2 Turn on. First, turn off the third switch S in advance. M1 Since the resonant current is less than zero at this time, the current will flow from the third switch S. M1 The diode continues to conduct, without affecting other parts of the circuit. After a short period of time, the sixth switch S is turned on. S2 If the second actual voltage is greater than the third actual voltage, due to the sixth switch S... S2 Since the voltage of the sixth switch S is always zero, it can be approximated that the voltage of the sixth switch S is zero. S2 Turn on at zero voltage. Finally, turn off the fourth switch S. M2 Under negative resonant current, the second switch S L2 and the fourth switch S M2The capacitor will be charged, and the fifth switch S S1 The capacitor will be discharged to zero, at which point the fifth switch S will be turned on. S1 Zero-voltage turn-on is achieved. If the second actual voltage is less than the third actual voltage, the sixth switch S... S2 It will hard conduct, the third switch S M1 The diode is turned off. Finally, the fourth switch S is turned off. M2 The fourth switch S M2 The voltage will remain zero. When the fifth switch S... S1 Zero-voltage turn-on is achieved when the turn-on signal arrives. Therefore, during the commutation process of the M-phase bridge arm and the S-phase bridge arm, the fifth switch S... S1 Zero-voltage turn-on can be achieved. The sixth switch, S... S2 Zero-voltage turn-on occurs when the second actual voltage is greater than the third actual voltage, and hard-conducting occurs when the second actual voltage is less than the third actual voltage. During hard-conducting, the voltage is very small, and the conduction voltage is the third actual voltage minus the second actual voltage.

[0059] During the commutation process of the S-phase bridge arm and the L-phase bridge arm, at time t8, the fifth switch S... S1 First turn it off, then at time t9, the second switch S... L2 and the fourth switch S M2 Turn on. If there is no misjudgment of the capacitor voltage, that is, the second actual voltage is greater than the third actual voltage, the third switch S will be turned on before the eighth time t8. M1 The diode is turned on. The fifth switch S is turned off. S1 At this time, the resonant current is greater than zero, and the second switch S L2 and the fourth switch S M2 The parallel capacitor is discharged, and the third switch S M1 and the fifth switch S S1 The parallel capacitor is charged. This is due to the fourth switch S... M2 The voltage across the parallel capacitor is very small and will be quickly discharged to zero at time t9, when the fourth switch S... M2 Zero-voltage turn-on. The other three capacitors continue to maintain their original charging and discharging states until the second switch S... L2 The voltage of the parallel capacitor is discharged to zero at time t9, when the second switch S... L2 Zero-voltage turn-on. If a misjudgment occurs in the capacitor voltage, i.e., the second actual voltage is less than the third actual voltage, the third switch S will be switched before time t8. M1 In the off state, the fourth switch S M2 The voltage across the parallel capacitor is zero. At time t8, the fifth switch S is turned off. S1 Then the fourth switch S M2 The diode is turned on, and at the ninth moment t9, the fourth switch S...M2 Zero-voltage turn-on. Second switching transistor S... L2 The voltage of the parallel capacitor continues to discharge to zero, and at the ninth moment t9, the second switch S... L2 Zero-voltage turn-on. Therefore, during the commutation process of the S-phase bridge arm and the L-phase bridge arm, regardless of whether the relationship between the second and third actual voltages is misjudged, the second switch S... L2 and the fourth switch S M2 Both can achieve zero-voltage start-up.

[0060] like Figure 6 As shown, an equivalent circuit corresponding to the commutation process of the S-phase bridge arm and L-phase bridge arm during the first LMS target driving strategy is provided. During the commutation of the S-phase bridge arm and L-phase bridge arm, the first switch S in the initial state... L1 Fifth switch S S1 and the sixth switch S S2 Turn on. If the second actual voltage is greater than the third actual voltage, then the third switch S... M1 The diode is turned on. The fifth switch S is turned off. S1 At this time, the resonant current is greater than zero, and the second switch S L2 and the fourth switch S M2 The parallel capacitor is discharged, and the third switch S M1 and the fifth switch S S1 The parallel capacitor is charged. This is due to the fourth switch S... M2 The voltage across the parallel capacitor is very small; even if the two capacitors are connected in series in this phase, it will be quickly discharged to zero. At this time, the fourth switch S... M2 Zero-voltage turn-on. The other three capacitors continue to maintain their original charging and discharging states until the second switch S... L2 The voltage of the parallel capacitor is discharged to zero, at which point the second switch S... L2 Zero-voltage turn-on. If the second actual voltage is less than the third actual voltage, then the third switch S... M1 In the off state, the fourth switch S M2 The voltage across the parallel capacitor is zero. Turn off the fifth switch S. S1 The fourth switch S M2 The diode is turned on, which supplies power to the fourth switch S. M2 On signal, fourth switch S M2 Zero-voltage turn-on. Second switching transistor S... L2 The voltage of the parallel capacitor continues to discharge to zero, at which point the second switch S... L2 Zero-voltage turn-on. Therefore, during the commutation process of the S-phase bridge arm and the L-phase bridge arm, regardless of whether the relationship between the second and third actual voltages is misjudged, the second switch S... L2 and the fourth switch S M2All can achieve zero-voltage turn-on. In practice, the fourth switch S... M2 Compared to the second switching transistor S L2 The connection can be made a little earlier or later, meaning that complete alignment is not required.

[0061] In the first case, when the difference between the second and third detected voltages is less than a preset threshold, that is, when the voltages of the M-phase bridge arm and the S-phase bridge arm are close, if the first commutation strategy is an LSM drive strategy at this time, then the first target drive strategy is the first LSM target drive strategy; the three-phase conversion half-bridge is driven by the first LSM target drive strategy in the corresponding switching cycle, so that the second, fourth, fifth, and sixth switches are turned on with zero voltage; and the third switch will not short-circuit when the second actual voltage is less than the third actual voltage, and the third switch is turned on with zero voltage when the second actual voltage is greater than the third actual voltage.

[0062] The LSM drive strategy indicates that when driving a three-phase converter half-bridge using the LSM drive strategy, commutation is performed in the order of L-phase bridge arm, S-phase bridge arm, and M-phase bridge arm. When the first commutation strategy is the LSM drive strategy, the first target drive strategy is the first LSM target drive strategy. That is, the commutation order of the three bridge arms corresponding to the first target drive strategy and the first commutation strategy remains unchanged, but the conduction timing of the switching transistors is changed. When driving the three-phase converter half-bridge using the first LSM target drive strategy, the second switching transistor S... L2 Fourth switch S M2 Fifth switch S S1 and the sixth switch S S2 Zero-voltage turn-on, the third switch S when the second actual voltage is less than the third actual voltage M1 Hard turn-on, when the second actual voltage is greater than the third actual voltage, the third switch S M1 Zero voltage start-up.

[0063] The first LSM target driving strategy includes: the first switch is continuously turned on during the switching cycle; during the switching cycle, the second switch is turned off at the first moment, the fourth switch is turned off at the second moment, and the fifth switch is turned on at the third moment; after the conduction duration of the third phase bridge arm, the sixth switch is turned off at the fourth moment, the third switch is turned on at the fifth moment, the fifth switch is turned off at the sixth moment, and the fourth switch is turned on at the seventh moment; after the conduction duration of the second phase bridge arm, the third switch is turned off at the eighth moment, and the second and sixth switches are turned on at the ninth moment, and the switching cycle ends after the conduction duration of the first phase bridge arm.

[0064] Specifically, such as Figure 7 As shown, during the entire switching cycle of the first LSM target-driven strategy, the first switching transistor S... L1It remains on. During the commutation process between the L-phase bridge arm and the S-phase bridge arm, the second switch S... L2 At the first moment t1, the fourth switch S is turned off. M2 The fifth switch S is turned off at the second time t2. S1 Zero-voltage turn-on is achieved at the third time t3. During the commutation process of the S-phase bridge arm and the M-phase bridge arm, the sixth switch S... S2 The third switch S is turned off at the fourth time t4. M1 At the fifth moment t5, the fifth switch S is turned on. S1 At time t6, the fourth switch S is turned off. M2 Zero-voltage turn-on is achieved at time t7 (the seventh time). The third switch S... M1 Zero-voltage turn-on is achieved when the second actual voltage is greater than the third actual voltage, and the third switch S... M1 The circuit is hard-turned on when the second actual voltage is less than the third actual voltage. During hard turn-on, the voltage is very small, and the turn-on voltage is the third actual voltage minus the second actual voltage. During the commutation process between the M-phase and L-phase bridge arms, the third switch S... M1 At time t8, the second switch S is turned off. L2 and the sixth switch S S2 Zero-voltage turn-on can be achieved at the ninth time t9.

[0065] In the second case, when the difference between the first and second detected voltages is less than a preset threshold, that is, when the voltages of the L-phase bridge arm and the M-phase bridge arm are close, if the first commutation strategy is an LMS drive strategy, then the second target drive strategy is a second LMS target drive strategy. In the corresponding switching cycle, the three-phase conversion half-bridge is driven by the second LMS target drive strategy to make the first, second, third, and fifth switches turn on with zero voltage. And when the first actual voltage is less than the second actual voltage, the fourth switch will not short-circuit, and when the first actual voltage is greater than the second actual voltage, the fourth switch turns on with zero voltage.

[0066] The LMS driving strategy indicates that when driving a three-phase converter half-bridge using the LMS driving strategy, commutation is performed in the order of L-phase bridge arm, M-phase bridge arm, and S-phase bridge arm. When the first commutation strategy is the LMS driving strategy, the second target driving strategy is the second LMS target driving strategy. That is, the commutation order of the three bridge arms remains unchanged in the second target driving strategy compared to the first commutation strategy, but the conduction timing of the switching transistors is changed. The first actual voltage is the actual voltage of the L-phase bridge arm during the operation of the three-phase converter half-bridge. The second actual voltage is the actual voltage of the M-phase bridge arm during the operation of the three-phase converter half-bridge. When driving the three-phase converter half-bridge using the second LMS target driving strategy, the first switching transistor S... L1 Second switch S L2 Third switch SM1 and the fifth switch S S1 Zero-voltage turn-on, the fourth switch S when the first actual voltage is less than the second actual voltage. M2 Hard turn-on, when the first actual voltage is greater than the second actual voltage, the fourth switch S M2 Zero voltage start-up.

[0067] The second LMS target driving strategy includes: the sixth switch is continuously turned on during the switching cycle; during the switching cycle, the fifth switch is turned off at the first moment, the third switch is turned off at the second moment, and the second switch is turned on at the third moment; after the duration of the first phase bridge arm's conduction, the first switch is turned off at the fourth moment, the fourth switch is turned on at the fifth moment, the second switch is turned off at the sixth moment, and the third switch is turned on at the seventh moment; after the duration of the second phase bridge arm's conduction, the fourth switch is turned off at the eighth moment, the fifth switch and the first switch are turned on at the ninth moment, and the switching cycle ends after the duration of the third phase bridge arm's conduction.

[0068] Specifically, such as Figure 8 As shown, the sixth switch S during the entire switching cycle of the second LMS target-driven strategy S2 It remains on. During the commutation process between the S-phase bridge arm and the L-phase bridge arm, the fifth switch S... S1 At the first moment t1, the third switch S is turned off. M1 The second switch S is turned off at the second time t2. L2 At the third moment t3, the transistor is turned on. During this process, regardless of whether the relationship between the first and second actual voltages is misjudged, the second switch S... L2 Both can achieve zero-voltage turn-on. During the commutation process of the L-phase bridge arm and the M-phase bridge arm, the first switching transistor S... L1 At the fourth time t4, the fourth switch S is turned off. M2 At the fifth moment t5, the second switch S is turned on. L2 At time t6, the third switch S is turned off. M1 At time t7, the transistor is turned on. During this process, the third switch S... M1 All can achieve zero-voltage turn-on. The fourth switch, S... M2 Zero-voltage turn-on is achieved when the first actual voltage is greater than the second actual voltage, and the fourth switch S... M2 When the first actual voltage is less than the second actual voltage, it hard-conducts. During hard-conduction, the voltage is very small, and the conduction voltage is the second actual voltage minus the first actual voltage. During the commutation process between the M-phase and S-phase bridge arms, the fourth switch S... M2 At time t8, the switch is turned off, and then the fifth switch S... S1 and the first switching transistor S L1 At the ninth moment, t9 is turned on, at which time the fifth switch S...S1 and the first switching transistor S L1 Both can achieve zero-voltage start-up.

[0069] In the second case, when the difference between the first and second detected voltages is less than a preset threshold, that is, when the voltages of the L-phase bridge arm and the M-phase bridge arm are close, if the first commutation strategy is an LSM drive strategy, then the second target drive strategy is a second LSM target drive strategy. In the corresponding switching cycle, the three-phase conversion half-bridge is driven by the second LSM target drive strategy to make the second, third, fourth, and fifth switches turn on with zero voltage. And when the first actual voltage is less than the second actual voltage, the first switch will not short-circuit, and when the first actual voltage is greater than the second actual voltage, the first switch turns on with zero voltage.

[0070] The LSM driving strategy indicates that when driving a three-phase converter half-bridge using the LSM driving strategy, commutation is performed in the order of L-phase bridge arm, S-phase bridge arm, and M-phase bridge arm. When the first commutation strategy is the LSM driving strategy, the second target driving strategy is the second LSM target driving strategy. That is, the commutation order of the three bridge arms remains unchanged compared to the first commutation strategy, but the conduction timing of the switching transistors is changed. When driving the three-phase converter half-bridge using the second LSM target driving strategy, the second switching transistor S... L2 Third switch S M1 Fourth switch S M2 and the fifth switch S S1 Zero-voltage turn-on, when the first actual voltage is less than the second actual voltage, the first switching transistor S L1 Hard turn-on occurs when the first actual voltage is greater than the second actual voltage, at which point the first switching transistor S... L1 Zero voltage start-up.

[0071] The second LSM target driving strategy includes: the sixth switch is continuously turned on during the switching cycle; during the switching cycle, the fifth switch is turned off at the first moment, the first switch is turned off at the second moment, and the fourth switch is turned on at the third moment; after the conduction duration of the second phase bridge arm, the fourth switch is turned off at the fourth moment, the first switch is turned on at the fifth moment, the third switch is turned off at the sixth moment, and the second switch is turned on at the seventh moment; after the conduction duration of the first phase bridge arm, the second switch is turned off at the eighth moment, and the third and fifth switches are turned on at the ninth moment, and the switching cycle ends after the conduction duration of the third phase bridge arm.

[0072] Specifically, such as Figure 9 As shown, the sixth switch S during the entire switching cycle of the second LSM target-driven strategy S2 It remains on. During the commutation process between the S-phase bridge arm and the M-phase bridge arm, the fifth switch S... S1At the first moment t1, the first switch S is turned off. L1 The fourth switch S is turned off at the second time t2. M2 Zero-voltage turn-on is achieved at the third time t3. During the commutation process of the M-phase bridge arm and the L-phase bridge arm, the fourth switch S... M2 At time t4, the first switch S is turned off. L1 At the fifth moment, t5 is turned on, and the third switch S... M1 At time t6, the second switch S is turned off. L2 Zero-voltage turn-on is achieved at time t7 (the seventh time). The first switching transistor S... L1 Zero-voltage turn-on is achieved when the first actual voltage is greater than the second actual voltage, and the first switching transistor S... L1 The circuit is hard-turned on when the first actual voltage is less than the second actual voltage. During hard turn-on, the voltage is very small, and the turn-on voltage is the second actual voltage minus the first actual voltage. During the commutation process between the L-phase and S-phase bridge arms, the second switch S... L2 At time t8, the third switch S is turned off. M1 and the fifth switch S S1 Zero-voltage turn-on can be achieved at the ninth time t9.

[0073] The driving method for the three-phase converter half-bridge provided in this application can avoid short circuits between phase capacitors and optimize the soft-switching performance of the three bidirectional switching transistors. In regions where the voltages of two-phase capacitors are similar, various switching sequences are employed based on the magnitude relationship of the three-phase capacitor voltages. By rationally setting the turn-on and turn-off times of the three bidirectional switching transistors, the soft-switching characteristics of the three bidirectional switching transistors are optimized, avoiding two-phase short circuits. Simultaneously, the switching losses on the AC side are optimized, efficiency is improved, the risk of two-phase short circuits is eliminated, and the performance of the three-phase converter half-bridge is significantly enhanced.

[0074] In one embodiment, a control component is also provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement any of the three-phase converter half-bridge driving methods described in the above embodiments. Specifically, the control component is connected to the three-phase converter half-bridge and is used to acquire the voltages of the three bridge arms and run the three-phase converter half-bridge driving method, transmitting the first commutation strategy or the first driving strategy to the six bidirectional switching diodes of the three-phase converter half-bridge to drive the three-phase converter half-bridge. The control component can be any component with data processing capabilities; this embodiment does not impose any specific limitation.

[0075] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A driving method for a three-phase converter half-bridge, characterized in that, A three-phase converter half-bridge includes three bridge arms. The upper bridge arm of each bridge arm includes two series-connected switching transistors, with the diodes in the two transistors having different orientations. The lower bridge arm of each bridge arm includes a capacitor. The method includes: The three-phase converter half-bridge is driven by the first commutation strategy; Obtain the first detection voltage, the second detection voltage, and the third detection voltage of the three arms of the three-phase converter half-bridge; the first detection voltage is greater than the second detection voltage, and the second detection voltage is greater than the third detection voltage; When the first detection voltage, the second detection voltage, and the third detection voltage meet the preset conditions, the three-phase conversion half-bridge is driven by the first driving strategy in the corresponding switching cycle so that the three arms of the three-phase conversion half-bridge can be commutated normally. The first detection voltage, the second detection voltage, and the third detection voltage satisfy the preset conditions including: the difference between the first detection voltage and the second detection voltage is less than a preset threshold, or the difference between the second detection voltage and the third detection voltage is less than a preset threshold. The first driving strategy is determined based on the first commutation strategy and the bridge arms corresponding to the two detection voltages that meet the preset conditions. The step of driving the three-phase converter half-bridge with a first driving strategy in the corresponding switching cycle when the first detection voltage, the second detection voltage, and the third detection voltage meet preset conditions, so that the three arms of the three-phase converter half-bridge can be normally commutated, includes: when the difference between the second detection voltage and the third detection voltage is less than a preset threshold, driving the three-phase converter half-bridge with a first target driving strategy in the corresponding switching cycle, so that at least some of the switches corresponding to the three arms of the three-phase converter half-bridge are turned on with zero voltage; and / or when the difference between the first detection voltage and the second detection voltage is less than a preset threshold, driving the three-phase converter half-bridge with a second target driving strategy in the corresponding switching cycle, so that at least some of the switches corresponding to the three arms of the three-phase converter half-bridge are turned on with zero voltage.

2. The method according to claim 1, characterized in that, The method further includes: The bridge arm corresponding to the first detection voltage is designated as the first phase bridge arm, the bridge arm corresponding to the second detection voltage is designated as the second phase bridge arm, and the bridge arm corresponding to the third detection voltage is designated as the third phase bridge arm; the upper bridge arm of the first phase bridge arm includes a first switch and a second switch connected in series; the upper bridge arm of the second phase bridge arm includes a third switch and a fourth switch connected in series, and the upper bridge arm of the third phase bridge arm includes a fifth switch and a sixth switch connected in series.

3. The method according to claim 2, characterized in that, The first target driving strategy includes: the third switch and the sixth switch are turned on alternately, and the fourth switch and the fifth switch are turned on alternately.

4. The method according to claim 3, characterized in that, When the difference between the second and third detection voltages is less than a preset threshold, the three-phase conversion half-bridge is driven in the corresponding switching cycle using a first target driving strategy, so that at least some of the switching transistors corresponding to the three arms of the three-phase conversion half-bridge are turned on with zero voltage, including: When the difference between the second and third detection voltages is less than a preset threshold, if the first commutation strategy is driven by the LMS drive strategy, then the first target drive strategy is the first LMS target drive strategy; the three-phase conversion half-bridge is driven by the first LMS target drive strategy in the corresponding switching cycle, so that the second, third, fourth, and fifth switches are turned on with zero voltage; and the sixth switch will not be short-circuited when the second actual voltage is less than the third actual voltage, and the sixth switch is turned on with zero voltage when the second actual voltage is greater than the third actual voltage. When the difference between the second and third detection voltages is less than a preset threshold, if the first commutation strategy is an LSM drive strategy, then the first target drive strategy is the first LSM target drive strategy; in the corresponding switching cycle, the three-phase conversion half-bridge is driven by the first LSM target drive strategy so that the second, fourth, fifth, and sixth switches are turned on with zero voltage; and when the second actual voltage is less than the third actual voltage, the third switch will not be short-circuited, and when the second actual voltage is greater than the third actual voltage, the third switch is turned on with zero voltage.

5. The method according to claim 4, characterized in that, The first LMS target-driven strategy includes: The first switching transistor remains on throughout the switching cycle; During the switching cycle, at the first moment, the second switch is turned off; at the second moment, the sixth switch is turned off; at the third moment, the third switch is turned on. After the conduction time of the second phase bridge arm, at the fourth moment, the third switch is turned off; at the fifth moment, the sixth switch is turned on; at the sixth moment, the fourth switch is turned off; at the seventh moment, the fifth switch is turned on. After the conduction time of the third phase bridge arm, at the eighth moment, the fifth switch is turned off; at the ninth moment, the second and fourth switches are turned on. After the conduction time of the first phase bridge arm, the switching cycle ends.

6. The method according to claim 4, characterized in that, The first LSM target-driven strategy includes: The first switching transistor remains on throughout the switching cycle; During the switching cycle, the second switch is turned off at the first moment, the fourth switch is turned off at the second moment, and the fifth switch is turned on at the third moment; after the conduction time of the third phase bridge arm, the sixth switch is turned off at the fourth moment, the third switch is turned on at the fifth moment, the fifth switch is turned off at the sixth moment, and the fourth switch is turned on at the seventh moment; after the conduction time of the second phase bridge arm, the third switch is turned off at the eighth moment, and the second and sixth switches are turned on at the ninth moment, and the switching cycle ends after the conduction time of the first phase bridge arm.

7. The method according to claim 2, characterized in that, The second target driving strategy includes: the first switch and the fourth switch are turned on alternately, and the second switch and the third switch are turned on alternately.

8. The method according to claim 7, characterized in that, When the difference between the first and second detected voltages is less than a preset threshold, the three-phase conversion half-bridge is driven in the corresponding switching cycle using a second target driving strategy, so that at least some of the switching transistors corresponding to the three arms of the three-phase conversion half-bridge are turned on with zero voltage, including: When the difference between the first detection voltage and the second detection voltage is less than a preset threshold, if the first commutation strategy is driven by the LMS drive strategy, then the second target drive strategy is the second LMS target drive strategy; the three-phase conversion half-bridge is driven by the second LMS target drive strategy in the corresponding switching cycle, so that the first switch, the second switch, the third switch and the fifth switch are turned on with zero voltage; and the fourth switch will not be short-circuited when the first actual voltage is less than the second actual voltage, and the fourth switch is turned on with zero voltage when the first actual voltage is greater than the second actual voltage. When the difference between the first detection voltage and the second detection voltage is less than a preset threshold, if the first commutation strategy is an LSM drive strategy at this time, then the second target drive strategy is a second LSM target drive strategy; in the corresponding switching cycle, the three-phase conversion half-bridge is driven by the second LSM target drive strategy so that the second, third, fourth and fifth switches are turned on with zero voltage; and when the first actual voltage is less than the second actual voltage, the first switch will not be short-circuited, and when the first actual voltage is greater than the second actual voltage, the first switch is turned on with zero voltage.

9. The method according to claim 8, characterized in that, The second LMS target-driven strategy includes: The sixth switch is continuously turned on during the switching cycle; During the switching cycle, at the first moment, the fifth switch is turned off; at the second moment, the third switch is turned off; at the third moment, the second switch is turned on. After the conduction time of the first phase bridge arm, at the fourth moment, the first switch is turned off; at the fifth moment, the fourth switch is turned on; at the sixth moment, the second switch is turned off; at the seventh moment, the third switch is turned on. After the conduction time of the second phase bridge arm, at the eighth moment, the fourth switch is turned off; at the ninth moment, both the fifth and first switches are turned on. After the conduction time of the third phase bridge arm, the switching cycle ends.

10. The method according to claim 8, characterized in that, The second LSM target-driven strategy includes: The sixth switch is continuously turned on during the switching cycle; During the switching cycle, at the first moment, the fifth switch is turned off; at the second moment, the first switch is turned off; at the third moment, the fourth switch is turned on. After the conduction time of the second phase bridge arm, at the fourth moment, the fourth switch is turned off; at the fifth moment, the first switch is turned on; at the sixth moment, the third switch is turned off; at the seventh moment, the second switch is turned on. After the conduction time of the first phase bridge arm, at the eighth moment, the second switch is turned off; at the ninth moment, both the third and fifth switches are turned on. After the conduction time of the third phase bridge arm, the switching cycle ends.

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