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US-12627217-B2 - Modular reconfigurable electrical AC/DC converter

US12627217B2US 12627217 B2US12627217 B2US 12627217B2US-12627217-B2

Abstract

An electrical converter may include AC terminals, a first and second DC terminal, and converter modules. Each of the converter modules has an AC node. The second DC terminal forms a common node of the converter modules. A connection between the AC nodes of the converter modules and the AC terminals is reconfigurable allowing the electrical converter to operate according to a first mode of operation converting between a first AC signal having a first plurality of phase voltages and the DC signal, in which the converter modules are grouped in first groups, and according to a second mode of operation converting between a second AC signal having a single-phase voltage and the DC signal, in which the converter modules are rearranged in second groups. The electrical converter is configured to operate multiple converter modules assigned to a same group of the first groups and the second groups in parallel.

Inventors

  • Johann Walter Kolar
  • David Menzi
  • Jordi Everts

Assignees

  • PRODRIVE TECHNOLOGIES INNOVATION SERVICES B.V.

Dates

Publication Date
20260512
Application Date
20210820
Priority Date
20200821

Claims (20)

  1. 1 . An electrical converter ( 10 , 20 ) for converting between an AC signal and a DC signal, the electrical converter comprising: a plurality of AC terminals (a, b, c, g, N), a first and a second DC terminal (DC + , DC − ), a plurality of converter modules ( 11 , 21 , 22 ), wherein each of the plurality of converter modules comprises: an AC node (a 1 , 111 ), a first capacitor (C), wherein the AC node (a 1 , 111 ) is connected to a first terminal of the first capacitor and the second DC terminal (DC − ) is connected to a second terminal of the first capacitor opposite the first terminal, such that the second DC terminal forms a common node of the first capacitors (C) of the plurality of converter modules, a first converter stage ( 12 ) comprising a first switch node (A), a first active semiconductor switch (T 1 ) connecting the first terminal of the first capacitor to the first switch node (A) and a second active semiconductor switch (T 2 ) connecting the second terminal of the first capacitor to the first switch node (A), a second converter stage ( 13 ) comprising a second switch node (B), a third active semiconductor switch (T 3 ) connecting the first DC terminal to the second switch node (B) and a fourth active semiconductor switch (T 4 ) connecting the second DC terminal to the second switch node (B), a first inductor (L), wherein the first and second switch nodes are connected to opposite terminals of the first inductor, wherein a connection between the AC nodes (a 1 , 111 ) of the plurality of converter modules and the plurality of AC terminals is reconfigurable allowing the electrical converter to operate according to a first mode of operation configured to convert between a first AC signal having a first plurality p 1 ≥2 of phase voltages and the DC signal and according to a second mode of operation configured to convert between a second AC signal having a single-phase voltage and the DC signal, such that the plurality of converter modules ( 11 , 21 , 22 ) contributing to converting between the first AC signal and the DC signal in the first mode of operation contribute to conversion between the second AC signal and the DC signal or to an active capacitive energy storage (C PPB ) in the second mode of operation, wherein the plurality of converter modules comprise at least p 1 k converter modules, k being a positive integer equal to or larger than two, wherein in the first mode of operation, the p 1 k converter modules are grouped in p 1 first groups ( 101 , 102 , 103 ), and wherein in the second mode of operation, the p 1 k converter modules are rearranged in two second groups ( 104 , 105 ) with a larger number of the plurality of converter modules assigned to a first one ( 105 ) of the two second groups and with at least two of the plurality of converter modules assigned to a second one ( 104 ) of the two second groups, wherein the electrical converter is configured to operate multiple converter modules assigned to a same group of the first groups and the second groups in parallel, wherein the second mode of operation comprises a boost mode of operation in which the electrical converter is configured to operate the plurality of converter modules assigned to the first one ( 105 ) of the two second groups via pulse width modulation, and to operate the plurality of converter modules assigned to the second one ( 104 ) of the two second groups according to an unfolder operation, such that the first active semiconductor switch (T 1 ) is switched to clamp the first switch node (A) to the respective AC node and the third active semiconductor switch (T 3 ) and one or both of the second and the fourth active semiconductor switches (T 2 , T 4 ) are switched to clamp the second switch node (B) alternatingly to respectively the first and the second DC terminal at half a fundamental period of the second AC signal.
  2. 2 . The electrical converter of claim 1 , wherein the second mode of operation comprises a buck mode of operation in which the electrical converter is configured to operate the plurality of converter modules assigned to the second one ( 104 ) of the two second groups according to the unfolder operation when a voltage across the respective first capacitors (C) is smaller than or equal to a voltage across the first and second DC terminals (U dc ), and to operate the plurality of converter modules assigned to the second one ( 104 ) of the two second groups via pulse width modulation when the voltage across the respective first capacitors (C) exceeds the voltage across the first and second DC terminals (U dc ).
  3. 3 . The electrical converter of claim 2 , wherein in the buck mode of operation, the electrical converter is configured to operate the plurality of converter modules assigned to the first one ( 105 ) of the two second groups in a clamped mode such that the first active semiconductor switch (T 1 ) is switched to clamp the first switch node (A) to the respective AC node and the fourth active semiconductor switch (T 4 ) is switched to clamp the second switch node (B) to the second DC terminal.
  4. 4 . The electrical converter of claim 1 , wherein p 1 ≥3.
  5. 5 . The electrical converter of claim 1 , wherein the first groups ( 101 , 102 , 103 ) have equal number of converter modules ( 11 , 21 ).
  6. 6 . The electrical converter of claim 1 , wherein the second AC signal has a single-phase voltage, and wherein the second groups are two ( 104 , 105 ).
  7. 7 . The electrical converter of claim 1 , further comprising a second capacitor (C dc ) connected across the first and second DC terminals, wherein the second converter stages of the plurality of converter modules are parallel connected to the second capacitor.
  8. 8 . The electrical converter of claim 1 , further comprising an AC filter ( 14 ) connected between the plurality of AC terminals (a, b, c, g, N) and the AC nodes ( 111 ), wherein the AC filter comprises a common mode filter comprising a common mode choke (L CM ).
  9. 9 . The electrical converter of claim 8 , wherein the common mode choke (L CM ) comprises a branch for each of the plurality of converter modules, wherein the branch is connected or connectable to the AC node ( 111 ) of the respective one of the plurality of converter modules.
  10. 10 . The electrical converter of claim 1 , further comprising first switching devices ( 112 ) for interconnecting terminals of the first capacitors (C) at a side of the AC node ( 111 ) in a reconfigurable manner.
  11. 11 . The electrical converter of claim 10 , wherein the first switching devices ( 112 ) are configured to interconnect the terminals of the first capacitors (C) of the converter modules assigned to a same group of the first groups and/or the second groups.
  12. 12 . The electrical converter of claim 10 , further comprising an AC filter ( 14 ) connected between the plurality of AC terminals (a, b, c, g, N) and the AC nodes ( 111 ), wherein the AC filter comprises a common mode filter comprising a common mode choke (L CM ), wherein the common mode choke (L CM ) comprises a branch for each of the plurality of converter modules, wherein the branch is connected or connectable to the AC node of the respective one of the plurality of converter modules, wherein the first switching devices ( 112 ) are configured to connect a first number of the branches to a second number of the plurality of converter modules, the first number and the second number being unequal.
  13. 13 . The electrical converter of claim 1 , further comprising a control unit ( 15 ), wherein the control unit is configured to operate the first and second active semiconductor switches mutually exclusively via pulse width modulation and the third and fourth active semiconductor switches mutually exclusively via pulse width modulation.
  14. 14 . The electrical converter of claim 1 , further comprising a control unit ( 15 ), wherein the control unit is configured to determine a duty cycle (d A , d B ) for each of the plurality of converter modules independently based on a first reference voltage (u* an , u* gn ) across the respective first capacitor (C).
  15. 15 . The electrical converter of claim 1 , wherein at least one of the plurality of converter modules ( 22 ) is configured to be operated as a power pulsation buffer in the second mode of operation, wherein the at least one converter module ( 21 ) configured to be operated as a power pulsation buffer is configured to charge and discharge the first capacitor (C) in the second mode of operation.
  16. 16 . The electrical converter of claim 1 , wherein at least one of the plurality of converter modules ( 22 ) is configured to be operated as a power pulsation buffer in the second mode of operation, wherein the at least one converter module ( 21 ) configured to be operated as a power pulsation buffer further comprises a buffer capacitor (C PPB ) and a second switching device configured to operably connect the buffer capacitor (C PPB ) to the at least one converter module ( 21 ) in the second mode of operation for charging and discharging the buffer capacitor.
  17. 17 . The electrical converter of claim 16 , wherein the second switching device is configured to connect the buffer capacitor (C PPB ) parallel to the first capacitor (C).
  18. 18 . The electrical converter of claim 16 , wherein the second switching device ( 212 ) is configured to switch connection of a terminal ( 213 ) of the first inductor (L) between the first switch node (A) and a terminal of the buffer capacitor (C PPB ), such that the second converter stage ( 13 ) is operable for charging and discharging the buffer capacitor in the second mode of operation.
  19. 19 . The electrical converter of claim 18 , wherein the second switching device ( 212 ) is further configured to connect a bridge-leg ( 24 ) of the first converter stage ( 12 ) between the first and second DC terminals and the first switch node (A) to a respective AC terminal in the second mode of operation.
  20. 20 . A battery charging system, wherein the battery charging system comprises a power supply, the power supply comprising the electrical converter ( 10 ) of claim 1 .

Description

TECHNICAL FIELD The present disclosure is related to an electrical AC/DC converter, allowing both single phase and three phase AC to DC operation. In particular, the present disclosure is related to such electrical converters allowing buck and boost capability. BACKGROUND In order to support further proliferation of Electric Vehicles (EVs), battery charger systems should allow for nominal power operation both in the case when attached to the European three-phase grid (e.g. 400 Vrms line-to-line voltage), as well as the US American split single-phase grid (e.g. 240 Vrms Vrms line-to-line voltage for a split single phase connection of 2×120 Vrms line-to-neutral voltage). Furthermore, charging systems are required to cover a wide DC output voltage range of typically 400 V-750 V in order to allow compatibility with various EV battery nominal voltages, such that buck-boost capability is required. A typical three-phase rectifier system can operate on the single-phase grid by attaching one phase terminal to the (first) line conductor and a second phase terminal to the neutral/second line conductor, where one phase terminal is not connected. As a result, only approximately ⅓ of the nominal output power can be provided in single-phase operation without overdimensioning of the employed components. WO 2020/079019 discloses an AC/DC converter topology allowing both three-phase and single-phase operation. In single-phase operation, the three phases of the rectifier are operated in parallel and connected to the line conductor, while the neutral conductor is connected to a low-frequency unfolder bridge-leg. A four phase common mode choke is required to avoid core saturation in single phase operation. This topology hence allows full power conversion both in three-phase and in single-phase operation. However, this topology comprises a single-stage Power Factor Correction (PFC) rectifier, which is limited to buck or boost operation and hence requires an additional DC/DC converter stage to comply with a wide DC output voltage range. Antivachis M. et al., Three-Phase Buck-Boost Y-Inverter with Wide DC Input Voltage Range, Proc. of the IEEE Applied Power Electronics Conference and Exposition (APEC), pp. 1492-1499, March 2018 discloses a phase-modular three-module Y-Inverter allowing three-phase boost and buck operation without the need for an additional DC/DC converter stage, leading to an ultra-compact and highly efficient converter realization. However, the Y-inverter only allows for three-phase operation. SUMMARY It is therefore an aim of the present disclosure to provide an electrical AC/DC converter allowing both three-phase and single-phase AC/DC conversion with improved system performance compared to prior art AC/DC converters, and possibly a reduced hardware count and/or without the need of component overdimensioning. It is an aim of the present disclosure to provide an electrical converter of the above type which allows to maintain modularity in three-phase as well as single-phase operation. According to a first aspect of the present disclosure, there is therefore provided an electrical converter as set out in the appended claims. Electrical converters as described herein are operable for converting between an AC signal and a DC signal, and are advantageously used for rectifier operation, inverter operation, or both, i.e. for bidirectional power flow. An electrical converter according to the present disclosure comprises a plurality of AC terminals, a first and a second DC terminal and a plurality of converter modules. Each of the plurality of converter modules comprises an AC node, a first converter stage comprising a first switch node, a second converter stage comprising a second switch node, a first inductor, and a first capacitor. The first and second switch nodes are connected to opposite terminals of the first inductor. The AC node and the second DC terminal are connected to opposite terminals of the first capacitor, such that the second DC terminal forms a common node of the first capacitors of the plurality of converter modules. A connection between the AC nodes of the plurality of converter modules and the plurality of AC terminals is reconfigurable allowing the electrical converter to operate according to a first mode of operation and according to a second mode of operation. The first mode of operation is configured to convert between a first AC signal having a first plurality p1≥2 of phase voltages and the DC signal. The second mode of operation is configured to convert between a second AC signal having a single-phase voltage or a second plurality p2 of phase voltages and the DC signal, such that the plurality of converter modules contributing to converting between the first AC signal and the DC signal in the first mode of operation contribute to conversion between the second AC signal and the DC signal or to an active capacitive energy storage in the second mode of operation. Electrical converters according