A three-phase bidirectional power converter and method thereof

Abstract

Embodiments of the present application relate to a three-phase bidirectional power converter (100) employing a soft switching unit (120). The three-phase bidirectional power converter (100) comprises a switching network (110), the soft switching unit (120), an input (130) and a DC bus (140). The three-phase bidirectional power converter (100) is configured to arrange switches in the switching network (110) into a switching pattern and release a current from the soft switching unit (120) to the switching network (110) according to the switching pattern to achieve zero voltage switching of the arranged switches in the switching network (110). Furthermore, the present application also relates to a corresponding method.

Description

Technical Field

[0001] This invention relates to a three-phase bidirectional power converter and a method for using a three-phase bidirectional power converter. Background Technology

[0002] The continued growth in demand for electric vehicle (EV) rectifiers and photovoltaic (PV) inverters has driven the demand for general-purpose bidirectional power converter systems.

[0003] Half-bridge (H-bridge) three-phase power converters are used to convert three-phase alternating current (AC) to direct current (DC), and are therefore widely used in applications such as power factor correction (PFC) rectifiers, EV fast charging stations, and PV inverter systems.

[0004] Power converters need to efficiently convert input voltage / current to output voltage / current. Summary of the Invention

[0005] One objective of this invention is to provide a solution that eliminates or solves the drawbacks and problems of conventional solutions.

[0006] Another objective of this invention is to provide a power converter that is small in size, has high power density, and high power conversion efficiency.

[0007] The foregoing and other objectives are achieved through the subject matter of the independent claims. Other embodiments of the invention can be found in the dependent claims.

[0008] According to a first aspect of the invention, the aforementioned objectives and other objectives are achieved by a three-phase bidirectional power converter (TPBPC). The TPBPC comprises: A switch network includes a first H-bridge arm, a second H-bridge arm, and a third H-bridge arm, wherein each H-bridge arm includes an upper switch, a lower switch, and a midpoint node disposed between the upper switch and the lower switch; A soft-switching unit includes a transformer and a current charging and discharging circuit, wherein the transformer includes a primary winding connected to the current charging and discharging circuit, and a first-stage winding, a second-stage winding, and a third-stage winding respectively connected to the first H-bridge arm, the second H-bridge arm, and the third H-bridge arm. The input terminals include a first port, a second port, and a third port respectively connected to the first stage winding, the second stage winding, and the third stage winding, and are used to receive the first phase voltage respectively. Second phase voltage and the third phase voltage ; The DC bus is connected to the first H-bridge arm, the second H-bridge arm, and the third H-bridge arm; the TPBPC is used for: The switches in the switch network are arranged into a switch pattern. According to the switch pattern, current is released from the soft-switching unit to the switch network to achieve zero-voltage switching of the array of switches in the switch network.

[0009] The advantage of the TPBPC according to the first aspect is that zero-voltage switching is achieved in current mode, rather than voltage mode, which results in a higher rate of voltage change (dv / dt). Therefore, the TPBPC of this invention requires fewer electrical components compared to conventional solutions because the power converter topology disclosed herein employs a soft-switching unit requiring fewer components. Furthermore, by designing the number of turns in the primary winding of the soft-switching unit transformer to be greater than the number of turns in its secondary winding, the root mean square (RMS) current flowing through the soft-switching unit can be kept at a low level. Moreover, the TPBPC disclosed herein has higher DC bus voltage utilization compared to conventional solutions, which indicates an improved modulation index of the power converter, thereby achieving higher power output to the load.

[0010] According to the first aspect, in one implementation of TPBPC, the current charging and discharging circuit includes a soft-switching unit switch connected in series with the soft-switching unit capacitor.

[0011] The advantage of this implementation is that, since the number of components required in the soft-switching unit is small, the soft-switching unit can achieve a compact structure and small size.

[0012] According to the first aspect, in one implementation of TPBPC, the positive terminal of the primary winding is connected to the drain of the soft-switching unit switch, and the negative terminal of the primary winding is connected to the soft-switching unit capacitor.

[0013] According to the first aspect, in one implementation of TPBPC, when the switching current is released into the switching network, the inductance of the transformer resonates with the capacitance of the soft-switching unit switch of the current charging and discharging circuit and the capacitance of the array switches in the switching network according to the switching pattern.

[0014] The advantage of this implementation is that all the arranged switches can simultaneously achieve soft switching according to the switch pattern.

[0015] According to the first aspect, in one implementation of TPBPC, the transformer is a flyback transformer.

[0016] According to the first aspect, in one implementation of TPBPC, releasing the switching current to the switching network includes: Set the soft switching unit to non-conducting mode.

[0017] The advantage of this implementation is that the soft-switching unit only needs to switch once in each switching cycle.

[0018] According to the first aspect, in one implementation of TPBPC, the time during which the soft-switching unit switch is in the non-conducting mode is less than or equal to 15% of the duty cycle of the TPBPC.

[0019] The advantage of this implementation is that, due to the short duty cycle of the soft-switching unit, the switching loss of the unit is low and negligible.

[0020] According to the first aspect, in one implementation of TPBPC, the arrangement of the switches in the switch network depends on their respective positions relative to the first phase voltage. The second phase voltage and the third phase voltage The associated first phase current Second phase current and the third phase current The polarity of.

[0021] According to the first aspect, in one implementation of TPBPC, the switches in the switch network are arranged according to the following table:

[0022] in, , and The upper switch for the corresponding H-bridge arm, , and The lower switch for the corresponding H-bridge arm.

[0023] According to the first aspect, in one implementation of TPBPC, the TPBPC is used for: The switches in the switch network are arranged, and the switch current is released simultaneously.

[0024] The advantage of this implementation is that the arrangement of switches achieves one soft switch within the switching cycle.

[0025] According to the first aspect, in one implementation of TPBPC, the TPBPC is used for: It operates in continuous conduction mode with a fixed switching frequency.

[0026] The advantages of this implementation are that the power converter design is simple and the TPBPC is easy to control. Furthermore, it allows for a smaller electromagnetic interference filter size.

[0027] According to the first aspect, in the implementation of TPBPC, the positive terminals of the first stage winding, the second stage winding, and the third stage winding are respectively connected to the source of the upper switch; the negative terminals of the first stage winding, the second stage winding, and the third stage winding are respectively connected to the first midpoint node, the second midpoint node, and the third midpoint node.

[0028] According to the first aspect, in the implementation of TPBPC, the positive terminals of the first stage winding, the second stage winding, and the third stage winding are respectively connected to the first midpoint node, the second midpoint node, and the third midpoint node; the negative terminals of the first stage winding, the second stage winding, and the third stage winding are respectively connected to the drain of the lower switch.

[0029] According to the first aspect, in one implementation of TPBPC, the TPBPC includes a filter circuit, wherein the filter circuit is connected between the input terminal and the first stage winding, the second stage winding, and the third stage winding.

[0030] The advantage of this implementation is that, because the zero-voltage switching is implemented in current mode, the common-mode noise is lower compared to zero-voltage switching implemented in voltage mode. This characteristic helps to reduce the size of the electromagnetic interference filter.

[0031] According to the first aspect, in one implementation of TPBPC, the filtering circuit includes a first filtering inductor connected between the first port and the negative terminal of the first primary winding, a second filtering inductor connected between the second port and the negative terminal of the second secondary winding, and a third filtering inductor connected between the third port and the negative terminal of the third secondary winding.

[0032] According to the first aspect, in one implementation of TPBPC, the DC bus includes a DC bus capacitor.

[0033] According to the first aspect, in one implementation of TPBPC, the DC bus is configured to function as an output source in the rectification mode or as an input source in the inverter mode of the TPBPC.

[0034] The advantage of this implementation is that TPBPC can achieve bidirectional power flow.

[0035] According to the first aspect, in one implementation of TPBPC, the positive terminal of the DC bus is connected to the drain of the upper switch, and the negative terminal of the DC bus is connected to the source of the lower switch.

[0036] According to a second aspect of the invention, the TPBPC includes a controller for controlling the TPBPC.

[0037] According to a third aspect of the present invention, the aforementioned objectives and other objectives are achieved through a method for TPBPC. The method comprises: A switch network includes a first H-bridge arm, a second H-bridge arm, and a third H-bridge arm, wherein each H-bridge arm includes an upper switch, a lower switch, and a midpoint node disposed between the upper switch and the lower switch; A soft-switching unit includes a transformer and a current charging and discharging circuit, wherein the transformer includes a primary winding connected to the current charging and discharging circuit, and a first-stage winding, a second-stage winding, and a third-stage winding respectively connected to the first H-bridge arm, the second H-bridge arm, and the third H-bridge arm. The input terminals include a first port, a second port, and a third port respectively connected to the first stage winding, the second stage winding, and the third stage winding, and are used to receive the first phase voltage respectively. Second phase voltage and the third phase voltage ; A DC bus is connected to the first H-bridge arm, the second H-bridge arm, and the third H-bridge arm; the method includes: The switches in the switch network are arranged into a switch pattern. According to the switch pattern, current is released from the soft-switching unit to the switch network to achieve zero-voltage switching of the array of switches in the switch network.

[0038] Other applications and advantages of the embodiments of the present invention will become apparent from the following detailed description. Attached Figure Description

[0039] The accompanying drawings are intended to illustrate and explain different embodiments of the invention, in which: – Figure 1 A TPBPC according to an embodiment of the present invention is shown; – Figure 2 A flowchart of a method according to an embodiment of the present invention is shown; – Figure 3 Different switch patterns are shown; – Figure 4 A TPBPC in a first connection pattern is shown according to an embodiment of the present invention; – Figure 5 A TPBPC in a second connection pattern is shown according to an embodiment of the present invention; – Figures 6a to 6k Different operating modes of TPBPC according to embodiments of the present invention are shown. Detailed Implementation

[0040] Over the past few years, various traditional solutions have been proposed for H-bridge power converters. Soft-switching technologies such as zero-voltage switching (ZVS) show great promise in these power converters. For power converters operating at high switching frequencies, soft switching can reduce the size of passive components such as inductors and capacitors, thereby reducing the size or weight of the power converter. Meanwhile, hard switching (i.e., without ZVS) limits the improvement of the power converter's switching frequency. Therefore, achieving soft switching reliably and at low cost is crucial for improving the switching frequency and power density of power converters. Therefore, this invention describes a power converter supporting ZVS.

[0041] Figure 1 A TPBPC 100 according to an embodiment of the present invention is shown. The TPBPC 100 includes a switch network 110, which includes a first H-bridge arm H1, a second H-bridge arm H2, and a third H-bridge arm H3. Each H-bridge arm includes an upper switch. , , Down switch , , and the switch set on top , , With the lower switch , , The midpoints A, B, and C between them. The TPBPC 100 also includes a soft-switching unit 120, which includes a transformer 122 and a current charging / discharging circuit 124. The transformer 122 includes a primary winding W1 connected to the current charging / discharging circuit 124, and a first-stage winding W21, a second-stage winding W22, and a third-stage winding W23 respectively connected to the first H-bridge arm H1, the second H-bridge arm H2, and the third H-bridge arm H3. The TPBPC 100 also includes an input terminal 130, which includes a first port 132, a second port 134, and a third port 136 respectively connected to the first-stage winding W21, the second-stage winding W22, and the third-stage winding W23, and is used to receive the first phase voltage. Second phase voltage and the third phase voltage The TPBPC 100 also includes a DC bus 140 connected to the first H-bridge arm H1, the second H-bridge arm H2, and the third H-bridge arm H3.

[0042] According to an embodiment of the present invention, TPBPC 100 is used to: arrange the switches in the switch network 110 into a switch pattern, and is also used to release current from the soft switching unit 120 to the switch network 110 according to the switch pattern, so as to realize zero-voltage switching of the arranged switches in the switch network 110.

[0043] Figure 2 It shows the use of Figure 1 The flowchart shows the corresponding method 200 for TPBPC 100. Method 200 for TPBPC 100 includes: • Arrange the switches in the switch network 110 into a switch pattern 202. • Current is released from soft switching unit 120 to switch network 110 according to the switching pattern to achieve zero-voltage switching of the array switches in switch network 110.

[0044] Therefore, this paper discloses a power converter scheme for implementing ZVS, which avoids the problems existing in traditional schemes, such as changing the bidirectional power flow characteristics of the power converter, changing the operating state of the converter under different load types, or causing a short circuit in the DC bus voltage during ZVS. Therefore, embodiments of the present invention are based on hardware and a method to inject the current required to achieve ZVS conduction, causing the array switches in the H-bridge power converter topology to enter the conducting state.

[0045] In this embodiment, the soft-switching unit 120 may employ a flyback transformer for energy storage. When ZVS is required, the stored energy is injected into the soft-switching unit 120 as a switching current, or the flyback transformer transfers the energy to the clamping capacitor. Therefore, the current charging and discharging circuit 124 may include the soft-switching unit capacitor. Series soft switching unit switch More specifically, the positive terminal of the primary winding W1 can be connected to the soft-switching unit switch. The drain of the primary winding W1, and the negative terminal of the primary winding W1, are connected to the soft-switching unit capacitor. One terminal, and the soft-switching unit capacitor. The other terminal is connected to the soft switching unit switch. The source. Flyback mode soft-switching unit switch. Turning off within a shorter duty cycle (e.g., ≤15%), i.e., in a non-conducting state, helps reduce the switching cost of the soft-switching unit. The losses are so small that they can be negligible.

[0046] Furthermore, the magnetizing inductance stored in the flyback transformer 122 The energy is injected into the aforementioned current, i.e., by releasing the current from the soft-switching unit 120 into the switching network 110, to simultaneously achieve ZVS turn-on of the array switches. This means, for example, during the ZVS process, when the currents in each phase current have phase... , , or , At that time, magnetized inductor With the capacitance of the array switch (i.e. , , and ) or with , , and Resonance occurs. In other words, when the switching current is released into the switching network 110, the inductance of the transformer 122... According to the switch diagram and the soft-switching unit switch of the current charging and discharging circuit 124, capacitor The capacitors of the array switches in the switching network 110 resonate.

[0047] Typically, the TPBPC 100 can be used to arrange the switches in the switch network 110 while simultaneously releasing the switching current. This can be understood as the switching current dropping below zero, allowing the body diodes of the arranged switches to conduct first, after which the switches can conduct under ZVS conditions.

[0048] Furthermore, the TPBPC 100 can be used to operate in continuous conduction mode at a fixed switching frequency. This reduces switching complexity due to the fixed switching frequency, making the TPBPC 100 easier to design and control. The switching frequency can be any suitable frequency, for example, in the kHz range or higher, such as 20 kHz, 50 kHz, 100 kHz, 150 kHz, 250 kHz, etc.

[0049] Figure 3 The H-bridge converter employing the proposed flyback soft-switching unit is shown during the switching cycle. The waveform within one modulation cycle. Voltage , , , , , These are switches , , , , , The gate-source voltage is used to drive the switch to the ON state. Current flows through the switch when it is ON, and no current flows when it is OFF. , , , , , , These are the current-carrying switches , , , , , The current indicates that the switch is in the ON state. Voltage It is the voltage across the transformer 122 in the soft-switching unit 120, which corresponds to the magnetizing inductance of the transformer 122. Current These are the current flowing through the magnetized inductor The current and the current flowing through the DC bus capacitor. Current , , These are flow filter inductors. , , The current.

[0050] It should be noted that the modulation principle used can be based on two types of carrier waves, namely... Figure 3 The ramp-up carrier shown and slope downcarrier When the filter current in any phase is positive, a ramp-up carrier is selected. When the filter current of any phase is negative, a ramp-down carrier is selected. This means that, in Figure 3 In the middle, the phase current is , , Then, the carrier is selected accordingly. , , These operating points are used to describe embodiments of the present invention in the following disclosure.

[0051] Table 1 shows the arrangement of the switches in the switching network 110 according to the phase current polarity at the hard-conduction moment. The left column of the table represents the phase current polarity, and the right column represents the arrangement of the switches. Therefore, the arrangement of the switches in the switching network 110 depends on their respective phase current polarities. Second phase voltage and the third phase voltage The associated first phase current Second phase current and the third phase current The polarity of the switches. Before the soft-switching unit 120 injects switching current, if the switches in the switching network 110 are turned on without the soft-switching unit 120 injecting switching current (referred to as hard conduction), these switches are arranged. Hard conduction means that the current and voltage are not zero before the switch is turned on. Therefore, hard conduction results in high switching losses. In contrast, soft switching, by turning on the switch when the switching voltage and current are zero, can make the switching losses very low or even negligible. In summary, the chosen modulation type makes it possible to arrange the switches at the hard conduction moment.

[0052] Table 1: Switches arranged according to phase current polarity

[0053] In addition, this article discloses as follows Figure 4 and Figure 5 The two different connection patterns shown are used to describe embodiments of the present invention in more detail, thereby providing a deeper understanding of the TPBPC 100 of the present invention. These connection patterns are referred to as the first connection pattern and the second connection pattern, respectively. However, these two connection patterns share some common features.

[0054] TPBPC 100 may include a filter circuit 150 connected between input terminal 130 and the first stage winding W21, the second stage winding W22, and the third stage winding W23. In an embodiment, the filter circuit 150 may include a first filter inductor connected between the first port 132 and the negative terminal of the first stage winding W21. The second filter inductor is connected between the second port 134 and the negative terminal of the second stage winding W22. and the third filter inductor connected between the third port 136 and the negative terminal of the third winding W23. .

[0055] Similarly, Figure 4 and Figure 5 As shown, DC bus 140 may include DC bus capacitor 142. Therefore, the positive terminal of DC bus 140 can be connected to the upper switch. , , The drain of the DC bus 140, the negative terminal of which can be connected to the lower switch. , , The source of the load. Furthermore, when operating in rectification mode, load 160 can be connected to DC bus 140. Load 160 can be any electrical device, unit, or apparatus that requires electrical energy to operate. Therefore, load 160 can be considered a power-consuming device.

[0056] The switches in the switch network 110 are illustrated as metal-oxide-semiconductor field-effect transistors (MOS-FETs). Therefore, each switch includes a diode and a capacitor, and includes a drain, a source, and a gate. However, other types of switches can also be used, such as insulated-gate bipolar transistors (IGBTs).

[0057] Figure 4 A TPBPC 100 employing a first connection pattern according to an embodiment of the present invention is shown. The TPBPC 100 includes a filter inductor. , , These filter inductors each have two terminals, with the first terminal of each phase connected to the three phase voltages respectively. , , The positive terminal of each phase and each second terminal are respectively connected to the lower switching device. , , The source pole. This connection forms, as... Figure 4 The midpoint nodes A, B, and C are shown. Current. It is the current flowing through the DC bus 140. It is the current flowing through the primary winding W1, and the voltage... It is the voltage across the primary winding W1.

[0058] The soft-switching unit 120 in flyback transformer mode includes a flyback transformer 122 and a clamping capacitor used as a voltage source. Magnetizing inductance as part of a transformer and soft switching unit switch .

[0059] The flyback transformer 122 includes a single primary winding W1 and three secondary windings W21, W22, and W23. The positive terminal of the primary winding W1 is connected to the soft-switching unit switch. The drain of the soft-switching unit is then connected to the source of the switch, which is then connected to the clamping capacitor. The clamping capacitor is then connected to the negative terminal of the primary winding W1. The voltage is... The first winding W21 has a voltage of The second winding W22 and the voltage are The third winding W23, their positive terminals are respectively connected to the upper switch. , , The drains, their negative terminals are connected to the lower switch. , , The source poles are the same as the midpoint nodes A, B, and C. It should be noted that the first-stage winding W21, the second-stage winding W22, and the third-stage winding W23 are respectively connected to the upper switch. , , Series connection.

[0060] Figure 5 A TPBPC 100 employing a second connection pattern according to an embodiment of the present invention is shown. The TPBPC 100 includes a filter inductor. , , These filter inductors each have two terminals, with the first terminal of each phase connected to the three-phase power grid. , , The positive terminal of each phase and each second terminal are respectively connected to the upper switch. , , The drain electrode. This connection forms a connection like... Figure 5The midpoint nodes A, B, and C are shown.

[0061] In this case, the soft-switching unit 120 in flyback transformer mode also includes a flyback transformer 122 and a clamping capacitor used as a voltage source. Magnetizing inductance as part of a transformer and soft switching unit switch .

[0062] The flyback transformer 122 includes a single primary winding W1 and three secondary windings W21, W22, and W23, as described above. The positive terminal of the primary winding W1 is connected to the soft-switching unit switch. The drain of the soft-switching unit is then connected to the source of the switch, which is then connected to the clamping capacitor. The clamping capacitor is then connected to the negative terminal of the primary winding W1. The voltage is... The first winding W21 has a voltage of The second winding W22 and the voltage are The third winding W23, their positive terminals are respectively connected to the upper switch. , , The drains of the electrodes, their negative terminals are respectively connected to the lower switch. , , The source poles are the same as those at the midpoint nodes A, B, and C. It should be noted that... , and Respectively with the lower switch , , Series connection.

[0063] Figure 4 and Figure 5 The following instructions apply to both the first and second connection patterns described.

[0064] In this embodiment, the TPBPC 100 includes a controller 170, which is described in detail below.

[0065] In this embodiment, the number of turns in the primary and secondary windings of transformer 122 can be selected according to the application. One option is to use a 1:1 turns ratio, where the number of turns in the primary winding is the same as the number of turns in the secondary winding. If it is necessary to reduce the RMS current in the soft-switching unit, more turns can be selected for the primary winding, for example, using a turns ratio of 1.1:1 or 1.2:1. According to Ohm's law, the higher the voltage, the lower the current; therefore, the more turns in the primary winding, the lower the RMS current in the soft-switching unit.

[0066] In this embodiment, the DC bus capacitor 142 is used as an input source in the inverter mode of the TPBPC 100 or as an output source in the rectification mode.

[0067] In this embodiment, the soft-switching unit 120 arranges the hard turn-on times of the main switch according to Table 1 using pulse width modulation (PWM). After this, the ZVS turn-on times of the switches listed in Table 1 can be synchronously realized.

[0068] In this embodiment, the soft-switching unit switches... Turning off at a small duty cycle (e.g., ≤15%), i.e., in a non-conducting state, makes switching losses negligible and creates a path for current injection during the ZVS process.

[0069] The magnetizing inductance stored in transformer 122 The energy in the circuit is used to achieve ZVS conduction of the array switches in the switching network 110. This represents the magnetized inductance. The capacitors resonate with the switches arranged in Table 1. For example, based on the operating point used in the previous analysis, the magnetizing inductor... and , , , or , , , Resonance occurs.

[0070] also, Figures 6a to 6k Different operating modes of the TPBPC 100 according to an embodiment of the present invention are shown. These operating modes are associated with different time periods defined by time. Key operating waveforms of the soft-switching unit 120 in flyback mode are shown below. Figure 3 As shown, the characteristics of this pattern will be analyzed and explained below. It should be noted that... Figures 6a to 6k The different components of TPBPC 100 are the same as those previously given in this invention in terms of reference numerals and names.

[0071] model - （ Figure 6a ） The hard switches are determined according to Table 1 using a modulation strategy, and the switches are arranged according to an embodiment of the present invention.

[0072] At any moment Switch , , It is about to be arranged and is in a non-conductive state.

[0073] In time Due to the filter current , , The function of the upper switch , , anti-parallel diode , , Conduction.

[0074] Soft switching unit switch During this stage, the transformer 122 is in a conducting state, and its magnetizing inductance... Clamped at the auxiliary capacitor voltage Above. The equation corresponding to this pattern is shown below: (1) (2) If the primary winding W1 and the secondary windings W21, W22, and W23 in transformer 122 have the same number of turns, then the following relationship exists: (3) (4) in, , , , They are magnetizing inductors The voltage across the terminals, the primary voltage of the transformer, the DC bus voltage, and the voltage flowing through the magnetizing inductor The current. , , These are the secondary voltages of the transformer at both ends of the secondary windings W21, W22, and W23, respectively.

[0075] model - （ Figure 6b ） At any moment Soft switching unit switch Turn off, clamping capacitor Used as a constant DC source.

[0076] Therefore, magnetized inductor With capacitor , , and Resonance occurs, where, , , It is in a discharging state, and It is currently charging.

[0077] Therefore, the following relation is obtained: (5) (6) set up , , Then we have: (7) model - （ Figure 6c ） capacitance , , The voltage across the capacitor has dropped to zero. Charged to .

[0078] diode , , , , , When in the conducting state, the switch... , , At any moment Achieve ZVS conduction.

[0079] Magnetized inductor The reverse recovery current of an anti-parallel diode can be suppressed using the following formula: (8) (9) Therefore, when the switch When in the conducting state, the magnetized inductor Suppression switch The reverse recovery of the body diode is the same as the reverse recovery, and this principle also applies to other H-bridge arms.

[0080] model - （ Figure 6d ） Current flowing through the diode , , The current drops to zero, therefore their corresponding switches , , It is in the conductive state.

[0081] When magnetizing inductor Current in When the diode drops to zero and Stop conducting, magnetize the inductor Clamped at voltage It continues to increase.

[0082] model - （ Figure 6e ） When the current Reduced to phase current When the value is , the diode When conduction stops, the following current relationship exists: = (10) As shown in equation (10), throughout the entire time period Inside, energy has been transferred to DC bus 140, and the following relationship exists: (11) (12) model - （ Figure 6f ） Magnetized inductor With capacitor , , and Resonance occurs, and the soft-switching unit switches. anti-parallel diode It will be connected soon.

[0083] At this stage, the capacitor , , Being charged, while the capacitor It was discharged.

[0084] At any moment The following equation exists: (13) set up , , Then we have: (14) model - （ Figure 6g ） switch , , It is in the ON state. Soft switching unit switch. It conducts under ZVS conditions.

[0085] capacitance From current The charging current is described by the following formula: .

[0086] switch At any moment Use a hard shutdown method to shut down.

[0087] model - （ Figure 6h ） In mode - A third resonance will occur at the beginning.

[0088] Phase current For capacitor Charge and make the capacitor Discharge. Phase current. Make the capacitor Discharge, and for the capacitor Charging. The following equation holds true in this mode: = (15) = (16) like Figure 3 As shown, at time In diode , After the circuit is turned on, the switch , Achieve ZVS conduction.

[0089] model - （ Figure 6i ） switch , , and Keeping the circuit open, power flows from the three-phase AC side to the DC bus 140.

[0090] Current When a capacitor is charged, its value is equal to: .

[0091] switch At any moment Use a hard shutdown method to shut down.

[0092] model - （ Figure 6j ） model - The phase current below Make the capacitor Discharge, and for the capacitor Charging should follow the formula below: (17) (18) model - （ Figure 6k ） In mode - Below, magnetized inductor The energy in the middle is transferred to the clamping capacitor. Until the working mode returns to the previous mode. .

[0093] Furthermore, in this embodiment of the invention, the TPBPC 100 includes a controller 170 or controller device 170 for controlling the TPBPC 100. This can be understood as the controller 170 controlling different components / parts in the TPBPC 100, such as the switch network 110, soft-switching unit 120, input terminal 130, DC bus 140, and filter circuit 150. Therefore, the controller 170 can be used to control the components / parts in the TPBPC 100 such that the TPBPC 100: arranges the switches in the switch network 110 into a switch pattern, and releases current from the soft-switching unit 120 to the switch network 110 according to the switch pattern, thereby achieving zero-voltage switching of the arranged switches in the switch network 110.

[0094] Controller 170 may be a digital controller connected to components / parts in TPBPC 100 to control them. Therefore, TPBPC 100 may include control lines and / or control buses between controller 170 and components / parts in TPBPC 100. These control lines and / or control buses can transmit control signals and control commands according to standardized procedures and protocols.

[0095] The controller 170 may include a processor and memory. The processor may be one or more general-purpose central processing units (CPUs), one or more digital signal processors (DSPs), one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), one or more programmable logic devices, one or more discrete gates, one or more transistor logic devices, one or more discrete hardware components, or one or more chipsets. The memory may be read-only memory, random access memory (RAM), or non-volatile RAM (NVRAM). A computer program may be executed by the processor to control the TPBPC 100.

[0096] Finally, it should be understood that the present invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

1. A three-phase bidirectional power converter (TPBPC) (100), characterized in that, include: The switching network (110) includes a first H-bridge arm (H1), a second H-bridge arm (H2), and a third H-bridge arm (H3), wherein each H-bridge arm includes an upper switch ( , , ), down switch ( , , ), and the switch located on the upper switch ( , , ) and the lower switch ( , , The midpoint nodes (A, B, C) between these points; The soft-switching unit (120) includes a transformer (122) and a current charging / discharging circuit (124), wherein the transformer (122) includes a primary winding (W1) connected to the current charging / discharging circuit (124), and windings connected to the first H-bridge arm (H1) and the second H-bridge arm (H2) respectively. The first stage winding (W21), the second stage winding (W22), and the third stage winding (W23) of the third H-bridge arm (H3). The input terminal (130) includes a first port (132), a second port (134), and a third port (136) respectively connected to the first stage winding (W21), the second stage winding (W22), and the third stage winding (W23), and is used to receive the first phase voltage respectively. Second phase voltage and the third phase voltage ; The DC bus (140) is connected to the first H-bridge arm (H1), the second H-bridge arm (H2), and the third H-bridge arm (H3); the TPBPC (100) is used for: The switches in the switch network (110) are arranged into a switch pattern. According to the switch pattern, current is released from the soft switching unit (120) to the switch network (110) to achieve zero-voltage switching of the arrangement of switches in the switch network (110).

2. The TPBPC (100) according to claim 1, characterized in that, The current charging and discharging circuit (124) includes a soft-switching unit capacitor ( ) series soft switching unit switch ( ).

3. The TPBPC (100) according to claim 2, characterized in that, The primary winding ( The positive terminal of ) is connected to the soft switching unit switch ( The drain of the primary winding ( The negative terminal of the soft-switching unit capacitor is connected to the capacitor of the soft-switching unit. ).

4. The TPBPC (100) according to claim 2 or 3, characterized in that, When the switching current is released into the switching network (110), the inductance of the transformer (122) ( According to the switch pattern and the soft switching unit switch of the current charging and discharging circuit (124), ) capacitance ( The capacitors of the array switches in the switch network (110) resonate.

5. The TPBPC (100) according to any one of the preceding claims, characterized in that, The transformer (122) is a flyback transformer.

6. The TPBPC (100) according to any one of the preceding claims, characterized in that, Releasing the switching current into the switching network (110) includes: Switch the soft switching unit ( Set to non-conducting mode.

7. The TPBPC (100) according to claim 6, characterized in that, The soft switching unit switch ( The time spent in the non-conducting mode is less than or equal to 15% of the duty cycle of the TPBPC (100).

8. The TPBPC (100) according to any one of the preceding claims, characterized in that, The arrangement of the switches in the switch network (110) depends on their respective voltages relative to the first phase voltage. The second phase voltage and the third phase voltage The associated first phase current Second phase current and the third phase current The polarity of.

9. The TPBPC (100) according to claim 8, characterized in that, The switches in the switch network (110) are arranged according to the following table: in, , and The upper switch for the corresponding H-bridge arm, , and The lower switch for the corresponding H-bridge arm.

10. The TPBPC (100) according to any one of the preceding claims, characterized in that, The TPBPC (100) is used for: The switches in the switch network (110) are arranged, and the switch current is released simultaneously.

11. The TPBPC (100) according to any one of the preceding claims, characterized in that, The TPBPC (100) is used for: It operates in continuous conduction mode with a fixed switching frequency.

12. The TPBPC (100) according to any one of claims 1 to 11, characterized in that, The positive terminals of the first-stage winding (W21), the second-stage winding (W22), and the third-stage winding (W23) are respectively connected to the upper switch ( , , The source pole of the first stage winding (W21), the second stage winding (W22) and the third stage winding (W23) are respectively connected to the first midpoint node (A), the second midpoint node (B) and the third midpoint node (C).

13. The TPBPC (100) according to any one of claims 1 to 11, characterized in that, The positive terminals of the first-stage winding (W21), the second-stage winding (W22), and the third-stage winding (W23) are respectively connected to the first midpoint node (A), the second midpoint node (B), and the third midpoint node (C); the negative terminals of the first-stage winding (W21), the second-stage winding (W22), and the third-stage winding (W23) are respectively connected to the lower switch ( , , The drain electrode of ).

14. The TPBPC (100) according to any one of the preceding claims, characterized in that, Includes a filter circuit (150), wherein the filter circuit (150) is connected between the input terminal (130) and the first stage winding (W21), the second stage winding (W22) and the third stage winding (W23).

15. The TPBPC (100) according to claim 14, characterized in that, The filter circuit (150) includes a first filter inductor connected between the first port (132) and the negative terminal of the first primary winding (W21). The second filter inductor is connected between the second port (134) and the negative terminal of the second secondary winding (W22). ), and a third filter inductor connected between the third port (136) and the negative terminal of the third stage winding (W23). ).

16. The TPBPC (100) according to any one of the preceding claims, characterized in that, The DC bus (140) includes a DC bus capacitor (142).

17. The TPBPC (100) according to any one of the preceding claims, characterized in that, The DC bus (140) is configured to be used as an output source in the rectification mode of the TPBPC (100) or as an input source in the inverter mode.

18. The TPBPC (100) according to any one of the preceding claims, characterized in that, The positive terminal of the DC bus (140) is connected to the upper switch ( , , The drain of the DC bus (140) is connected to the negative terminal of the lower switch. , , The source pole of ).

19. A method (200) for TPBPC (100), characterized in that, include: The switching network (110) includes a first H-bridge arm (H1), a second H-bridge arm (H2), and a third H-bridge arm (H3), wherein each H-bridge arm includes an upper switch ( , , ), down switch ( , , ), and the switch located on the upper switch ( , , ) and the lower switch ( , , The midpoint nodes (A, B, C) between these points; The soft-switching unit (120) includes a transformer (122) and a current charging / discharging circuit (124), wherein the transformer (122) includes a primary winding connected to the current charging / discharging circuit (124). ), and the first stage winding (W21), the second stage winding (W22) and the third stage winding (W23) respectively connected to the first H-bridge arm (H1), the second H-bridge arm (H2) and the third H-bridge arm (H3). The input terminal (130) includes a first port (132), a second port (134), and a third port (136) respectively connected to the first stage winding (W21), the second stage winding (W22), and the third stage winding (W23), and is used to receive the first phase voltage respectively. Second phase voltage and the third phase voltage ; A DC bus (140) is connected to the first H-bridge arm (H1), the second H-bridge arm (H2), and the third H-bridge arm (H3); the method (200) includes: The switches in the switch network (110) are arranged (202) into a switch pattern. According to the switching pattern, current is released (204) from the soft switching unit (120) to the switching network (110) to achieve zero-voltage switching of the arrangement of switches in the switching network (110).

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