Switching unit for power converter, method of operating switching unit, and power converter
By adopting a magnetic coupling structure and an embedded leakage coupling transformer switch unit design in the power converter, the problem of high conduction and shutdown losses under partial loads is solved, and a smaller and cost-effective power conversion system is achieved.
Patent Information
- Application Number
- CN202280100783.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2022-10-26
- Publication Date
- 2025-05-13
AI Technical Summary
Existing power converters are difficult to effectively reduce on- and off losses under partial loads, while increasing losses under heavy loads, resulting in increased system size and cost.
The switching unit design is adopted that includes a magnetic coupling structure and an embedded leakage coupling transformer. By assisting with DC voltage and soft switching circuit optimization, the on- and off losses are reduced and additional losses are avoided under heavy loads.
Reduce on and off losses under partial loads, reduce semiconductor footprint and auxiliary circuit losses, reduce the number and size of magnetic components, while maintaining system energy efficiency under heavy loads.
Smart Images
Figure CN119999060A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates generally to power conversion, and more particularly to a switch unit for a power converter, a method of operating the switch unit, and a power converter including the switch unit. Background Art
[0002] Power converters consisting of modular switching cells or "legs" are widely used in various industries such as photovoltaics and automotive. The two-level half-bridge (2L-HB) switching cells or "legs" used in many converters usually experience conduction and switching losses, which affect the efficiency of the system. In order to improve energy efficiency while not (or only slightly) affecting power density, we need to reduce conduction and turn-off losses with minimal effort. Soft-switching (SS) strategies / topologies are one way to achieve this goal.
[0003] Most SS strategies rely on the use of active auxiliary components during commutation. These components increase the size of the converter and limit its power density.
[0004] One fundamental way to limit the size of the auxiliary / SS system is to restrict its operation, for example, to only operate at light loads. This is because, for many applications, the switch unit operates most of the time at partial loads and rarely at heavy loads.
[0005] Various exemplary schemes focus only on reducing the conduction loss. For example, a capacitor can be added in parallel to the main switch of the switching unit to reduce the turn-off loss. However, this leads to higher conduction losses when operating outside the SS region. This can only be avoided if the operating range of the SS covers the full load range, but this in turn leads to large / expensive SS circuits.
[0006] Other exemplary schemes achieve reduced turn-on and turn-off losses in a given operating range without affecting the rest of the range, but at the expense of higher current stress on the inductor and auxiliary switches. This results in larger chip area, larger magnetic components, and higher conduction losses.
[0007] Topologies and methods that can improve efficiency at partial loads without increasing losses at heavy loads are desirable because they can result in smaller and / or more cost-effective SS power conversion systems. Summary of the invention
[0008] The object is to overcome these and other disadvantages. The above and other objects are achieved by the features of the independent claims. Other implementations are apparent from the dependent claims, the description and the drawings.
[0009] According to a first aspect, a switch unit for a power converter is provided. The switch unit includes: an input rail, a direct-current (DC) voltage source for the power converter; an output rail, a load for the power converter; a ground rail; a first main power switch, inserted between the input rail and the output rail; a second main power switch, inserted between the output rail and the ground rail; a series connection of a first auxiliary power switch and a first coil of a coupling transformer, the first auxiliary power switch and the first coil of the coupling transformer being inserted between the input rail and the output rail; a series connection of a second coil of the coupling transformer and a second auxiliary power switch, the second coil of the coupling transformer and the second auxiliary power switch being inserted between the output rail and the ground rail; a first discharge circuit, for providing a lower potential lower than the potential of the ground rail; a second discharge circuit, for providing a higher potential higher than the potential of the input rail; a first demagnetization circuit, connected to the first discharge circuit and a common end of the first auxiliary power switch and the first coil of the coupling transformer; a second demagnetization circuit, connected to a common end of the second auxiliary power switch and the second coil of the coupling transformer and the second discharge circuit.
[0010] As used herein, a power converter may refer to a class of electrical devices used to process and control the flow of electrical energy by providing voltage and current in a form suitable for its electrical load. Power converters are often classified based on the type of power conversion they implement (e.g., DC / DC, DC / AC, AC / DC, AC / AC).
[0011] As used herein, a switch cell or "branch" may refer to a type of circuit topology that constitutes a modular building block of a power converter. For example, one switch cell or more than one switch cell connected in series or in parallel may constitute a part of a power converter.
[0012] Rail or power rail as used herein may refer to a metallic conductor, such as a bar or rod-shaped conductor, used for power feeder / transmission lines.
[0013] As used herein, a power switch or power switch may refer to an active electrical device used to switch high rated voltage / current. For example, a common solid-state power switch may include a power metal-oxide-semiconductor field-effect transistor (MOSFET), a power bipolar transistor, or a power insulated-gate bipolar transistor (IGBT). A power MOSFET may have parasitic capacitance in parallel with its drain-source current path. Similarly, a power IGBT and a power bipolar transistor may have parasitic capacitance in parallel with its collector-emitter current path.
[0014] The coupling transformer used herein may refer to a passive electrical device for inductively coupling one circuit including a primary winding (first coil) of the transformer and another circuit including a secondary winding (second coil) of the transformer through magnetic flux in the transformer core. Since leakage magnetic flux outside the primary winding and the secondary winding passes through the path, the coupling transformer may have a leakage inductance in series with the mutually coupled transformer windings.
[0015] As used herein, a demagnetization circuit may refer to a circuit for demagnetizing an inductive circuit component (eg, windings of a transformer or an inductor).
[0016] A discharge circuit as used herein may refer to a circuit for further discharging and thereby resetting the above-mentioned inductive circuit components for subsequent commutation.
[0017] Common as used herein may refer to the common potential of the electrical interconnection ends of circuit components.
[0018] The proposed switch cell reduces turn-on and turn-off losses within a given operating range (partial load) without adversely affecting its energy efficiency at heavy loads (e.g., when the soft-switching circuit is disabled).
[0019] More specifically, the magnetic coupling structure reduces current stress in the semiconductor by 40%, reduces semiconductor footprint by 52%, and reduces semiconductor turn-on and turn-off losses in the auxiliary circuit by 49%.
[0020] The coupling transformer with embedded leakage reduces the number and size of magnetic components by 50% and 18%, respectively.
[0021] The auxiliary DC voltage enables resetting the coupling transformer after each commutation.
[0022] Charging the auxiliary capacitor only when soft switching is enabled avoids additional losses at heavy loads or when soft switching is disabled. The soft switching circuit can be optimized for a given operating range.
[0023] The proposed switch cell can be deployed as a 2L-HB branch in any DC / DC or DC / AC converter that relies on a 2L-HB branch as the main switching unit, for example, in a multi-phase system or other architectures. The need for SS is particularly important in hard-switching topologies, such as PWM-driven DC / AC converters (inverters) used in photovoltaic and automotive systems.
[0024] In a possible implementation, the main power switch may have a corresponding parasitic parallel capacitance.
[0025] Parasitic shunt capacitance can be used for soft switching without increasing the size of the converter or limiting its power density.
[0026] In a possible implementation manner, the coil of the coupling transformer may have a corresponding leakage series inductance.
[0027] The leakage series inductor can be used for soft switching without increasing the size of the converter or limiting its power density.
[0028] In a possible implementation, the first demagnetization circuit may include a series connection of first diodes inserted between the lower potential of the first discharge circuit and a common potential of the first auxiliary power switch and the first coil of the coupling transformer.
[0029] In a possible implementation, the first demagnetization circuit may also be connected to the output rail, and may further include: a first soft switching capacitor inserted between the potential of the output rail and the common potential of the first diode.
[0030] In one possible implementation, the second demagnetization circuit may include a series connection of second diodes inserted between a common potential of the second auxiliary power switch and the second coil of the coupling transformer and the higher potential of the second discharge circuit.
[0031] In a possible implementation, the second demagnetization circuit may also be connected to the output rail, and may further include: a second soft switching capacitor inserted between the potential of the output rail and the common potential of the second diode.
[0032] In a possible implementation, the first discharge circuit may include: a first DC voltage source connected to the potential of the ground rail; the second discharge circuit may include: a second DC voltage source connected to the potential of the input rail.
[0033] In a possible implementation, the first discharge circuit and the second discharge circuit may further include: corresponding resistors connected in parallel to the corresponding first DC voltage source and second DC voltage source.
[0034] In a possible implementation, the first discharge circuit may also include: a first power regeneration converter inserted between the lower potential of the first discharge circuit and the potential of the ground rail; the second discharge circuit may also include: a second power regeneration converter inserted between the higher potential of the second discharge circuit and the potential of the input rail.
[0035] In one possible implementation, the first power regeneration converter and the second power regeneration converter may include buck-boost converter circuits, respectively.
[0036] In a possible implementation, the first power regeneration converter and the second power regeneration converter may include flyback converter circuits, respectively.
[0037] In a possible implementation, the first DC voltage source and the second DC voltage source may form part of a power supply circuit for supplying power to a circuit connectable to the switching unit.
[0038] According to a second aspect, there is provided a multiphase DC-AC power converter comprising a parallel connection of one or more switching units according to the first aspect or any implementation thereof.
[0039] According to a third aspect, a method for operating a switch unit according to the first aspect or any implementation thereof is provided. The method comprises: during a commutation period from the second main power switch to the first main power switch, if the magnitude of the current output to the load is lower than a current threshold, switching the first auxiliary power switch on; when the magnitude of the voltage across the first main power switch is lower than a voltage threshold, switching the first main power switch on; when switching the first main power switch on, switching the first auxiliary power switch off at the earliest.
[0040] In a possible implementation, switching the first auxiliary power switch on may further include: switching the first auxiliary power switch on at the latest when the second main power switch is switched off.
[0041] In a possible implementation, the method may further include: during commutation from the first main power switch to the second main power switch, if the magnitude of the current input from the load is lower than the current threshold, switching the second auxiliary power switch on; when the magnitude of the voltage across the second main power switch is lower than the voltage threshold, switching the second main power switch on; when switching the second main power switch on, switching the second auxiliary power switch off at the earliest.
[0042] In a possible implementation, switching the second auxiliary power switch on may further include: switching the second auxiliary power switch on at the latest when the first main power switch is switched off.
[0043] According to a fourth aspect, a computer program is provided, comprising a program code, which, when executed on a computer, is used to execute the method according to the third aspect or any implementation thereof. BRIEF DESCRIPTION OF THE DRAWINGS
[0044] The above aspects and implementations are now explained with reference to the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements.
[0045] The drawings should be considered schematic representations, and the elements shown in the drawings are not necessarily shown to scale. Rather, various elements are shown so that their function and general purpose are apparent to those skilled in the art.
[0046] Figures 1 to 3 The circuit topology of the switching unit according to the present invention is shown in different levels of detail respectively;
[0047] Figures 4 to 7 The circuit topology of the discharge circuit according to the present invention is respectively shown;
[0048] Figure 8 The circuit topology of the multi-phase DC / AC power converter according to the present invention is shown;
[0049] Fig. 9 Shows the operation Figure 3 A flow chart of a method for a switching unit in;
[0050] Fig.10 and Fig.11 Shows Figure 3 The working mode of the switching unit in the period when the first main power switch is turned on. DETAILED DESCRIPTION
[0051] In the following description, reference is made to the accompanying drawings that form a part of the present invention, which illustrate by way of illustration specific aspects of embodiments of the present invention or specific aspects in which embodiments of the present invention may be used. It should be understood that embodiments of the present invention may be used in other aspects and may include structural or logical changes not described in the accompanying drawings. Therefore, the following detailed description should not be understood in a restrictive sense, and the scope of the present invention is defined by the appended claims.
[0052] For example, it should be understood that the disclosure related to describing a method may also be applicable to a corresponding device or system for performing the method, and vice versa. For example, if one or more specific method steps are described, the corresponding device may include one or more units (e.g., functional units) to perform the described one or more method steps (e.g., one unit performs one or more steps, or multiple units perform one or more steps of multiple steps respectively), even if such one or more units are not explicitly described or illustrated in the drawings. On the other hand, for example, if a specific device is described based on one or more units (e.g., functional units), the corresponding method may include a step to perform the function of one or more units (e.g., one step performs the function of one or more units, or multiple steps perform the function of one or more units of multiple units respectively), even if such one or more steps are not explicitly described or illustrated in the drawings. In addition, it should be understood that, unless otherwise specifically noted, the features of the various exemplary embodiments and / or aspects described herein may be combined with each other.
[0053] Figures 1 to 3 The circuit topology of the switching unit 1 according to the invention is shown in each case in different degrees of detail.
[0054] The switch unit 1 is suitable for use in a power converter 2 as described below in conjunction with Figure 8 The multi-phase DC / AC power converter 2 is explained in more detail.
[0055] according to Figure 1, the switch unit 1 comprises: an input rail 101, a direct-current (DC) voltage source UDC (DC link voltage) for the power converter 2; an output rail 102, a load (indicated by the load current Iload) for the power converter 2; a ground rail 103; a first main power switch 104, S1, inserted between the input rail 101 and the output rail 102; a second main power switch 105, S2, inserted between the output rail 102 and the ground rail 103; a series connection of a first auxiliary power switch 106, S3 and a first coil 107 of a coupling transformer 107, 108, the first auxiliary power switch 106, S3 and the first coil 107 of the coupling transformer 107, 108 being inserted between the input rail 101 and the output rail 102; the coupling transformer 107, 108 The second coil 108 and the second auxiliary power switch 109, S4 are connected in series, the second coil 108 and the second auxiliary power switch 109, S4 of the coupling transformers 107 and 108 are inserted between the output rail 102 and the ground rail 103; the first discharge circuit 110 is used to provide a lower potential lower than the potential of the ground rail 103; the second discharge circuit 111 is used to provide a higher potential higher than the potential of the input rail 101; the first demagnetization circuit 112 is connected to the first discharge circuit 110 and the common end of the first auxiliary power switch 106, S3 and the first coil 107 of the coupling transformers 107 and 108; the second demagnetization circuit 113 is connected to the second auxiliary power switch 109, S4 and the common end of the second coil 108 of the coupling transformers 107 and 108 and the second discharge circuit 111.
[0056] The main power switch 104, S1; 105, S2 may specifically comprise a MOSFET involving a corresponding parasitic body diode with a parasitic parallel capacitance 114, Coss, S1; 115, Coss, S2.
[0057] The auxiliary power switches 106, S3; 109, S4 may have bidirectional conduction capability (eg, MOSFET with / without anti-parallel diode or IGBT with anti-parallel diode).
[0058] The coupling transformers 107, 108 are used to magnetically couple the first auxiliary power switch 106, S3 and the second auxiliary power switch 109, S4 so that current is shared between them during commutation. For example, the turns ratio of the coupling transformers 107, 108 may include 1:1.
[0059] The coils of the coupling transformers 107, 108 may have respective leakage series inductances 116, L11; 117, L12. The leakage inductances may be used during commutation of the switching unit.
[0060] according to Figure 2The first demagnetization circuit 112 may include a series connection of first diodes 1121, D1a; 1122, D1b, and the first diodes 1121, D1a; 1122, D1b are inserted between the lower potential of the first discharge circuit 110 and the common potential of the first auxiliary power switch 106, S3 and the first coil 107 of the coupling transformer 107, 108.
[0061] Similarly, the second demagnetization circuit 113 may include a series connection of second diodes 1131, D2a; 1132, D2b, and the second diodes 1131, D2a; 1132, D2b are inserted between the common potential of the second auxiliary power switch 109, S4 and the second coil of the coupling transformer 107, 108 and the higher potential of the second discharge circuit 111.
[0062] according to Figure 3 The first demagnetization circuit 112 may also be connected to the output rail 102 and may further include: a first soft switching capacitor 1123, Cx1, inserted between the potential of the output rail 102 and the common potential of the first diodes 1121, D1a; 1122, D1b.
[0063] Similarly, the second demagnetization circuit 113 may also be connected to the output rail 102 and may further include: a second soft switching capacitor 1133, Cx2, inserted between the potential of the output rail 102 and the common potential of the second diodes 1131, D2a; 1132, D2b.
[0064] The first soft switch capacitor 1123, Cx1 and the second soft switch capacitor 1133, Cx2 are charged only when SS is enabled.
[0065] Figures 4 to 7 The circuit topologies of the discharge circuits 110 and 111 according to the present invention are respectively shown.
[0066] according to Figure 4 The first discharge circuit 110 may include: a first DC voltage source 1101 , Uaux, connected to the potential of the ground rail 103 ; the second discharge circuit 111 may include: a second DC voltage source 1111 , Uaux, connected to the potential of the input rail 101 .
[0067] according to Figure 5 The first discharge circuit 110 and the second discharge circuit 111 may further include: corresponding resistors 1102, 1112, Rdis, connected in parallel to the corresponding first DC voltage source 1101, Uaux and the second DC voltage source 1111, Uaux.
[0068] according to Figure 6The first discharge circuit 110 may further include: a first power regeneration converter 1103, inserted between the lower potential of the first discharge circuit 110 and the potential of the ground rail 103; the second discharge circuit 111 may further include: a second power regeneration converter 1113, inserted between the higher potential of the second discharge circuit 111 and the potential of the input rail 101.
[0069] according to Figure 7 As a first example, the first power regeneration converter 1103 and the second power regeneration converter 1113 may respectively include buck-boost converter circuits 1104, 1114. As a second example, the first power regeneration converter 1103 and the second power regeneration converter 1113 may respectively include flyback converter circuits.
[0070] The auxiliary power supplies Uaux act as sinks. That is, after each use, these auxiliary power supplies help discharge / reset the coupling transformers 107, 108, thereby recovering energy during commutation. This energy can be dissipated through dedicated resistors (see Figure 5 ), or it can be fed back into the DC link or other auxiliary power supply. For this purpose, one or two power converters are required (see Figure 6 ). These converters can be isolated or non-isolated. For example, Figure 7 The case where a non-isolated buck-boost converter is used is shown. Optionally, a flyback converter (not shown) can be used to provide energy to a secondary power supply, such as a power supply for powering gate drivers, sensors, etc.
[0071] Figure 8 A circuit topology of a multi-phase DC / AC power converter 2 according to the present invention is shown.
[0072] According to the first aspect of the present invention or any implementation thereof, the converter 2 comprises a parallel connection of more than one switching unit 1 .
[0073] Figure 8 The specific implementation in includes N=3 switch units 1 and can be deployed in a three-phase inverter for driving a three-phase load (indicated by load currents Iload A, Iload B, and Iload C). A similar setup can be extended to N phases without limitation. Although each phase A, B, C, ... requires a dedicated auxiliary / SS circuit, only two discharge circuits 110, 111 are required regardless of the number of phases.
[0074] Fig. 9 Shows the operation Figure 3 Flow chart of method 3 of switching unit 1 in FIG.
[0075] Method 3 is used to operate the switch unit 1 according to the first aspect of the present invention or any implementation thereof.
[0076] The following steps 31 to 33 are applicable during the on-time of the first main power switch 104, S1.
[0077] Method 3 comprises the step of switching 31 the first auxiliary power switch 106, S3 on if the magnitude of the current Iload output to the load is below a current threshold during commutation from the second main power switch 105, S2 to the first main power switch 104, S1. This corresponds to the operating mode "Mode 1" explained in more detail below. The step may also comprise: switching 311 the first auxiliary power switch 106, S3 on at the latest when the second main power switch 105, S2 is switched off.
[0078] Method 3 further comprises the step of switching 32 the first main power switch 104, S1 on when the magnitude of the voltage across the first main power switch 104, S1 is below a voltage threshold. This corresponds to an operating mode "Mode 3" discussed in more detail below.
[0079] The method 3 further comprises the step of switching 33 the first auxiliary power switch 106, S3 non-conductive at the earliest when the first main power switch 104, S1 is switched conductive. This corresponds to the operating mode "Mode 4" described in more detail below.
[0080] Similar considerations / steps 34 to 36 apply during the on-time of the second main power switch 105, S2.
[0081] Method 3 may further include: during the commutation from the first main power switch 104, S1 to the second main power switch 105, S2, if the magnitude of the current Iload input from the load is lower than the current threshold, switching 34 the second auxiliary power switch 109, S4 to be turned on. This step may also include: when switching 33 the first main power switch 104, S1 is not turned on, switching 341 the second auxiliary power switch 109, S4 to be turned on at the latest.
[0082] The method 3 may further include: when the voltage across the second main power switch 105, S2 is lower than a voltage threshold, switching 35 the second main power switch 105, S2 on.
[0083] The method 3 may further comprise: when switching 35 the second main power switch 105 , S2 is turned on, switching 36 the second auxiliary power switch 109 , S4 is not turned on at the earliest.
[0084] Fig.10 and Fig.11 The operating mode of the proposed switch unit 1 during the conduction period of the first main power switch 104, S1 is shown.
[0085] exist Fig.10 and Fig.11 In the first operation mode (“Mode 1”) shown, the first auxiliary power switch 106, S3 is turned on by zero-current switching (ZCS).
[0086] Zero current switching as used herein may refer to (soft) switching when the current in the current path of the switch is substantially zero (eg, below a given ZCS current threshold).
[0087] The anti-parallel diode of the second auxiliary power switch 109, S4 is forward biased, and the currents Ipri and Isec in the transformer windings 107 and 108 are 0.5U DC / L l1,2 The current I flowing to the main power switch 104, S1; 105, S2 increases at a given rate. mid It is the sum of these two currents Ipri and Isec.
[0088] exist Fig.10 and Fig.11 In the second operating mode ("Mode 2") shown in FIG. mid When the load current is reached, the leakage series inductance is 116, L l1 ;117,L l2 Resonance with the parasitic parallel capacitance 114, Coss, S1; 115, Coss, S2 of the main power switch 104, S1; 105, S2. More specifically, the parasitic parallel capacitance 115, Coss, S2 is charged, while the parasitic parallel capacitance 114, Coss, S1 is discharged.
[0089] exist Fig.10 and Fig.11 In the third operation mode (“Mode 3”) shown, the main power switch 104, S1 is turned on by zero-voltage switching (ZVS) when the voltage across the parasitic shunt capacitor 114, Coss, S1 is substantially zero (eg, below a given voltage threshold).
[0090] Zero voltage switching as used herein may refer to (soft) switching when the voltage on a current path of the switch is substantially zero (eg, below a given ZVS voltage threshold).
[0091] Once the main power switch 104, S1 is turned on, the currents Ipri, Isec in the transformer windings 107, 108 start to flow at a rate of 0.5U DC / L l1,2 The rate of decay.
[0092] exist Fig.10 and Fig.11 In the fourth operating mode ("Mode 4") shown, the first auxiliary power switch 106, S3 is turned off by ZVS. The leakage series inductor 116, L l1 Through the first diode 1121, D 1a is the first soft switch capacitor 1123, C x1 Charge.
[0093] If the leakage series inductance is 116, L l1 The energy in the first soft switch capacitor 1123, C x1 The voltage will be charged to a level equal to the DC link voltage U dc and auxiliary power supply voltage U aux The voltage U cap =U dc +U aux , and Mode 5 will start. Otherwise, the first soft switching capacitor 1123, C x1 will be charged to a lower value and due to the leakage series inductance 116, L l1 The current in will reach zero, so Mode 5 is bypassed.
[0094] exist Fig.10 and Fig.11 In the fifth operating mode (“Mode 5”) shown, the leakage series inductance 116, L l1 The diode D 1b Polarization. The current in the transformer winding 107 is (U dc +0.5U aux ) / L l1 At the end of mode 5, through the leakage series inductance 117, L l2 The current in the magnetizing inductance of transformers 107 and 108 is zero. However, the current in the magnetizing inductance of transformers 107 and 108 still exists. This results in two other operating modes.
[0095] exist Fig.10 and Fig.11 In the sixth operating mode (“Mode 6”) shown, the leakage series inductor 117, L l2 The current is -0.5(U cap +U aux ) / L l2 The given rate becomes negative. When the complete magnetizing current flows through the leakage series inductance 117, L L2 When the loop ends, the mode ends.
[0096] exist Fig.10 and Fig.11 In the seventh operating mode (“Mode 7”) shown in FIG. 1 , the leakage series inductor 117, L l2 The current is U aux / Lmag The rate increases and is fed into the second discharge circuit 111, U aux At the end of this mode, the transformer resets once the magnetizing energy has been restored.
[0097] Fig.10 and Fig.11 The eighth operating mode ("Mode 8") shown is activated during the off period of the main power switch 104, S1; 105, S2. In order to turn off the main power switch 104, S1, the voltage across the parasitic shunt capacitor 114, Coss, S1 needs to rise before the diode of the main power switch 105, S2 is turned on. To this end, the parasitic shunt capacitor 114, Coss, S1 is charged, while the parasitic shunt capacitor 115, Coss, S2 and the first soft switch capacitor 1123, C x1 This process reduces the current flowing through the main power switch 104, S1 during commutation, resulting in lower switching losses in the main power switch 104, S1.
[0098] Similar considerations apply to the second main power switch 105, S2.
[0099] The present invention has been described in conjunction with various embodiments as examples and implementations. However, according to the study of the drawings, the present invention and the independent claims, those skilled in the art can understand and implement other variations when implementing the claimed subject matter. In the claims and the specification, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" does not exclude multiple. A single element or other unit can meet the functions of several entities or items set forth in the claims. The fact that certain measures are set forth in mutually different dependent claims does not indicate that the combination of these measures cannot be used in an advantageous implementation. The computer program can be stored or distributed on a suitable medium (e.g., an optical storage medium or solid-state medium provided together with other hardware or as a part of other hardware), and can also be distributed in other forms (e.g., via the Internet or other wired or wireless telecommunications systems).
Claims
1. A switch unit (1) for a power converter, characterized in that: The switch unit (1) comprises: - an input rail (101) for a direct-current (DC) voltage source (U DC ); - an output rail (102) for a load of said power converter; - a ground rail (103); - a first main power switch (104, S1) interposed between the input rail (101) and the output rail (102); - a second main power switch (105, S2) inserted between said output rail (102) and said ground rail (103); - a series connection of a first auxiliary power switch (106, S3) and a first coil (107) of a coupling transformer (107, 108), the first auxiliary power switch (106, S3) and the first coil (107) of the coupling transformer (107, 108) being inserted between the input rail (101) and the output rail (102); - a series connection of a second coil (108) of the coupling transformer (107, 108) and a second auxiliary power switch (109, S4), the second coil (108) of the coupling transformer (107, 108) and the second auxiliary power switch (109, S4) being inserted between the output rail (102) and the ground rail (103); - a first discharge circuit (110) for providing a lower potential than the potential of the ground rail (103); - a second discharge circuit (111) for providing a higher potential than the potential of the input rail (101); - a first demagnetization circuit (112) connected to the first discharge circuit (110) and a common end of the first auxiliary power switch (106, S3) and the first coil (107) of the coupling transformer (107, 108); - a second demagnetization circuit (113) connected to the second auxiliary power switch (109, S4) and the common end of the second coil (108) of the coupling transformer (107, 108) and the second discharge circuit (111).
2. The switch unit (1) according to claim 1, characterized in that - The main power switches (S1, S2) have corresponding parasitic parallel capacitances (114, C oss,S1 ;115,C oss,S2 ).
3. The switch unit (1) according to claim 1 or 2, characterized in that: - the coils of the coupling transformers (107, 108) have corresponding leakage series inductances (116, L l1 ;117,L l2 ).
4. The switch unit (1) according to any one of claims 1 to 3, characterized in that: The first demagnetization circuit (112) comprises: - A first diode (1121, D 1a ;1122,D 1b ) are connected in series, the first diode (1121, D 1a ;1122,D 1b ) is inserted between the lower potential of the first discharge circuit (110) and the common potential of the first auxiliary power switch (106, S3) and the first coil (107) of the coupling transformer (107, 108).
5. The switch unit (1) according to claim 4, characterized in that The first demagnetization circuit (112) is also connected to the output rail (102) and further comprises: - The first soft switch capacitor (1123, C x1 ), inserted between the potential of the output rail (102) and the first diode (1121, D 1a ;1122,D 1b ) between the common potentials of the two electrodes.
6. The switch unit (1) according to any one of claims 1 to 5, characterized in that: The second demagnetization circuit (113) comprises: - The second diode (1131, D 2a ;1132,D 2b ) are connected in series, the second diode (1131, D 2a ;1132,D 2b ) is inserted between the common potential of the second auxiliary power switch (109, S4) and the second coil of the coupling transformer (107, 108) and the higher potential of the second discharge circuit (111).
7. The switch unit (1) according to claim 6, characterized in that The second demagnetization circuit (113) is also connected to the output rail (102) and further comprises: - The second soft switch capacitor (C x2 ), inserted between the potential of the output rail (102) and the second diode (1131, D 2a ;1132,D 2b ) between the common potentials of the two electrodes.
8. The switch unit (1) according to any one of claims 1 to 7, characterized in that: The first discharge circuit (110) comprises: a first DC voltage source (1101, U aux ), connected to said potential of said ground rail (103); The second discharge circuit (111) comprises: a second DC voltage source (1111, U aux ), connected to the potential of the input rail (101).
9. The switch unit (1) according to claim 8, characterized in that The first discharge circuit (110) and the second discharge circuit (111) further include: corresponding resistors (1102, 1112, R dis ), connected in parallel to the corresponding first DC voltage source (1101, U aux ) and a second DC voltage source (1111, U aux ).
10. The switch unit (1) according to claim 8, characterized in that The first discharge circuit (110) further comprises: a first power regeneration converter (1103) inserted between the lower potential of the first discharge circuit (110) and the potential of the ground rail (103); The second discharge circuit (111) further includes: a second power regeneration converter (1113) inserted between the higher potential of the second discharge circuit (111) and the potential of the input rail (101).
11. The switch unit (1) according to claim 10, characterized in that The first power regeneration converter (1103) and the second power regeneration converter (1113) include buck-boost converter circuits (1104, 1114), respectively.
12. The switch unit (1) according to claim 10, characterized in that The first power regeneration converter (1103) and the second power regeneration converter (1113) each include a flyback converter circuit.
13. The switch unit (1) according to claim 6, characterized in that The first DC voltage source (1101, U aux ) and the second DC voltage source (1111, U aux ) forms part of a power supply circuit for supplying power to a circuit that can be connected to the switching unit (1).
14. A multiphase DC-AC power converter (2), characterized in that: include: A parallel connection of one or more switching units (1) according to any one of claims 1 to 13.
15. A multi-level DC-AC power converter (3), characterized in that: include: A series connection of one or more switching units (1) according to any one of claims 1 to 13.
16. A method (3) for operating a switch unit (1) according to any one of claims 1 to 13, characterized in that: The method (3) comprises: - During the commutation from the second main power switch (105, S2) to the first main power switch (104, S1), if the current (I load ) is lower than the current threshold, switching (31) the first auxiliary power switch (106, S3) to conduct; - when the voltage across the first main power switch (104, S1) is lower than a voltage threshold, switching (32) the first main power switch (104, S1) on; - When switching (32) the first main power switch (104, S1) to be turned on, the first auxiliary power switch (106, S3) is switched off at the earliest (33).
17. The method (3) according to claim 16, characterized in that The switching (31) of the first auxiliary power switch (106, S3) to be turned on further comprises: - When the second main power switch (105, S2) is switched off, the first auxiliary power switch (106, S3) is switched on at the latest (311).
18. The method (3) according to claim 16 or 17, characterized in that Also includes: - During the commutation from the first main power switch (104, S1) to the second main power switch (105, S2), if the current (I load ) is lower than the current threshold, switching (34) the second auxiliary power switch (109, S4) to conduct; - when the voltage across the second main power switch (105, S2) is lower than the voltage threshold, switching (35) the second main power switch (105, S2) on; - When switching (35) the second main power switch (105, S2) to be conductive, the second auxiliary power switch (109, S4) is switched non-conductive at the earliest (36).
19. The method (3) according to claim 18, characterized in that The switching (34) of the second auxiliary power switch (109, S4) to be turned on further comprises: - When the first main power switch (104, S1) is switched off (33), the second auxiliary power switch (109, S4) is switched on at the latest (341).
20. A computer program, characterized in that It comprises a program code for executing the method (3) according to claims 16 to 19 when the program code is executed on a computer.