Multi-point inverter with mechanically switched discharge resistor and grounding switch

Abstract

The invention relates to a multi-stage converter (1) comprising a capacitor (2); a resistor (3); a first switch (4) actuated by a first motor drive (40); a second switch (5) actuated by a second motor drive (50); the first switch (4) connects the capacitor (2) and the resistor (3) in a closed state and short-circuits the capacitor; the second switch (5) connects the capacitor (2) to a ground potential (20) in a closed state.

Description

Technical Field

[0001] The invention relates to a multi-level converter. Background Art

[0002] In principle, a multi-level converter includes a plurality of semiconductor switches, capacitors and coils. The installed capacitors usually store a large amount of energy. In order to achieve reliable maintenance or interference suppression of the multi-level converter, all components must be placed in a voltage-free state before maintenance. Summary of the invention

[0003] The object of the present invention is to provide a multi-level converter which is easy to maintain and has a simple construction and which can moreover be placed reliably and repeatedly into a voltage-free state.

[0004] This object is achieved by a device according to claim 1. Advantageous developments are described in the dependent claims.

[0005] According to a first embodiment of the present invention, a multi-level converter is provided, comprising:

[0006] - capacitors;

[0007] -resistance;

[0008] - a first switch, which is operated by a first motor drive;

[0009] - a second switch, which is operated by a second motor drive; wherein,

[0010] - the first switch connects the capacitor and the resistor and short-circuits the capacitor in a closed state;

[0011] The second switch connects the capacitor to the ground potential when in a closed state;

[0012] - Closing the first switch before closing the second switch.

[0013] The multi-level converter is designed particularly simply and cost-effectively for disconnection, i.e., for discharge and for grounding. The multi-level converter then assumes a voltage-free state. The first and second switches have their own motor drive that can be controlled separately. After the capacitor is short-circuited by the first switch, the capacitor is discharged as far as possible by means of a resistor or via the resistor. The second switch finally grounds the capacitor and ensures that the multi-level converter is placed in a voltage-free state. Thus, during actuation, the switches are closed in a fixed sequence.

[0014] The multi-level converter can be designed in any desired manner, wherein:

[0015] - the first switch comprises first and second contact teeth;

[0016] - the first and second contact teeth are electrically conductively connected to the resistor;

[0017] The first contact tooth, the resistor and the second contact tooth form a series circuit.

[0018] The contact teeth each have a contact surface.

[0019] The multi-level converter can be designed in any desired manner, wherein:

[0020] - the second switch comprises a movable contact;

[0021] The movable contact is electrically conductively connected to the ground potential.

[0022] The movable contact can be designed as a contact rail which is electrically conductively connected to the ground potential, for example via a cable.

[0023] The multi-level converter can be designed in any desired manner, wherein:

[0024] - a contact module having a first access contact and a second access contact is provided;

[0025] - the first access contact has a first contact point and a second contact point;

[0026] The second access contact has a first contact point and a second contact point.

[0027] The multi-level converter can be designed in any desired manner, wherein:

[0028] - in the closed state of the first switch, the first contact tooth contacts the first contact point of the first access contact, and the second contact tooth contacts the first contact point of the second access contact, and

[0029] In the closed state of the second switch, the movable contact connects the second contact point of the first access contact and the second contact point of the second access contact.

[0030] Thus, the first switch is formed by the contact tooth and the first contact point of the first and second access contacts. Thus, the second switch is formed by the movable contact and the second contact point of the first and second access contacts.

[0031] Alternatively, the contact rail contacts the first and the second access contact.

[0032] The multi-level converter can be designed in any desired manner, wherein:

[0033] - The capacitor is part of a battery.

[0034] The multi-level converter can be designed in any desired manner, wherein:

[0035] - a plurality of capacitors are provided, said capacitors being part of a single battery;

[0036] - provided with a plurality of batteries;

[0037] - Each battery is provided with a first access contact and a second access contact;

[0038] - Each battery can be discharged via two contact teeth and a resistor respectively;

[0039] - Each battery can be grounded via a common movable contact.

[0040] Depending on the requirements, the multi-level converter can have a plurality of capacitors, which are arranged individually or together in the battery. In an embodiment with a plurality of batteries, each of the batteries must be designed to be connectable to a first switch and a second switch. A separate resistor or multiple resistors can be assigned to each battery. Each battery is connected to a common second switch, so that the battery can be connected to ground potential via the second switch. Each battery can be assigned its own first switch, via which the capacitor of the battery is discharged.

[0041] The multi-level converter can be designed in any desired manner, wherein:

[0042] - Twelve batteries are provided, and each battery outputs a voltage of 2 kV.

[0043] The multi-level converter can be designed in any desired manner, wherein:

[0044] - The multilevel converter operates in the medium voltage range of 20 kV.

[0045] The multi-level converter can be designed in any desired manner, wherein:

[0046] Each battery has at least one semiconductor switching element and at least one inductor.

[0047] According to a further specific embodiment, a method for switching off the multi-level converter is provided, wherein:

[0048] In a first step, the first switch is actuated by a first motor drive and the capacitor is short-circuited by means of a resistor;

[0049] - In a second step, the second switch is actuated by the second motor drive, and the capacitor is connected to ground potential;

[0050] - The second step is performed when the capacitor has been discharged.

[0051] When the multi-level converter is switched off, i.e. switched without voltage, the capacitor is discharged and, after its discharge, an additional grounding of the capacitor is performed. It is important here that the grounding, i.e. the actuation of the second switch, is performed only when the capacitor is completely or at least almost completely discharged. This allows reliable operation of the multi-level converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The present invention and its advantages are described in detail below with reference to the accompanying drawings.

[0053] Figure 1 A circuit for a multi-level converter is shown;

[0054] Figure 2 showing a first detailed view of a multi-level converter having a first switch and a second switch;

[0055] Figure 3 showing a second detailed view of a multi-level converter having a first switch and a second switch;

[0056] Figure 4 A detailed view of the first switch and the second switch is shown. DETAILED DESCRIPTION

[0057] The same reference numerals are used for the same or identically functioning elements of the invention. Moreover, for the sake of clarity, only the reference numerals necessary for describing the respective figure are shown in the individual figures. The embodiments shown merely form an example of how the multi-level converter according to the invention can be constructed and thus do not constitute a final limitation of the invention.

[0058] Figure 1A first embodiment of a multilevel converter 1 is shown. This multilevel converter has at least one capacitor 2, which is part of a battery 9. In addition, at least one resistor 3 is provided, which can be switched in parallel with the capacitor 2 or connected to the capacitor by means of a first switch 4 and a first motor drive 40, whereby the capacitor 2 is short-circuited with or via the resistor 3. In addition, a second switch 5 is provided, which can connect the capacitor 2 to the ground potential 20 by means of a second motor drive 50. When the capacitor 2 is short-circuited with or via the resistor 3, the capacitor 2 is discharged. When the capacitor 2 is connected to the ground potential 20, the capacitor 2 is grounded. The short-circuiting is always performed before the grounding. After the short-circuiting and grounding of the capacitor, which is associated with the discharge, work, such as maintenance, etc., can be performed on the multilevel converter without any risk to people. In the embodiment shown here, the multilevel converter 1 has a battery 9, which has a capacitor 2. Preferably, the multilevel converter 1 can have twelve batteries 9, each of which has at least one capacitor 2.

[0059] Figures 2 to 4 A detailed view of a multi-level converter 1 and first and second switches 4, 5 is shown. All components of the multi-level converter 1 are arranged in a housing 10 having a frame. The first switch 4 has at least one first contact tooth 4.1 and at least one second contact tooth 4.2. Each contact tooth is constructed by a support having a first contact plate and a second contact plate, and the contact plates are arranged on two opposite sides of the support. Each of the contact teeth 4.1, 4.2 or the contact plates of each contact tooth is preferably connected to at least one resistor 3 via a first and a second conductor 6.1, 6.2. The contact teeth 4.1, 4.2 and the at least one resistor 3 form a series circuit via the conductors 6.1, 6.2. In addition, the contact teeth 4.1, 4.2 are arranged on a terminal strip 41. The terminal strip 41 is designed from a non-conductive material, so that the two contact teeth 4.1, 4.2 are insulated from each other, that is, non-conductive. The terminal strip 41 is preferably connected to a first motor drive 40 via a mechanism 42, for example, constructed as a toggle lever device. The first motor drive 40 is preferably constructed as a linear motor with a rotating spindle.

[0060] The second switch 5 has a movable contact 5.1, which is designed as a contact rail. The movable contact 5.1 or the rail is preferably connected to the ground potential 20 via a wire (not shown here). The second switch 5 and in particular its movable contact 5.1 are preferably actuated by another mechanism 52, which is designed, for example, as a bending lever device, and a second motor drive 50. The second motor drive 50 is preferably designed as a linear motor with a rotating spindle.

[0061] Furthermore, a contact module 7 is provided, which can be connected both by the first switch and by the second switch 4, 5. In this case, the contact module 7 has at least one first access contact 7.1 and at least one second access contact 7.2, which are arranged on an insulating material support. The two access contacts 7.1, 7.2 each have a first contact point 7.11, 7.21 and a second contact point 7.12, 7.22. The first access contact 7.1 is electrically conductively connected to the first side 2.1 of the capacitor 2, and the second access contact 7.2 is electrically conductively connected to the second side 2.2.

[0062] The first motor drive 40 actuates the first switch 4 in such a way that the first motor drive 40 acts on the mechanism 42 on the terminal strip 41. In this case, the terminal strip 41 performs a vertical movement from bottom to top toward the contact module 7. Thus, when the first switch 4 is actuated, the first contact tooth 4.1 is connected via the first contact point 7.11 of the first access contact 7.1 and the second contact tooth 4.2 is connected via the first contact point 7.21 of the second access contact 7.2. In this case, the capacitor 2 is short-circuited via the resistor 3 and discharged.

[0063] The second motor drive 50 operates the second switch 5 in such a way that the second motor drive 50 acts on the movable contact 5.1 by means of the mechanism 52. Here, the movable contact 5.1 performs a vertical movement from bottom to top toward the contact module 7. Here, it is preferred to pass through a distance of at least 280 mm. This distance is particularly set within the scope of use of a 20 kV multi-level converter. In other words, the second contact points 7.12, 7.22 of the access contacts 7.1, 7.2 are at least 280 mm away from the movable contact 5.1 in the open state, that is, in the non-conductive state. Therefore, when the second switch 5 is operated, the movable contact 5.1 is conductively connected to the access contacts 7.1, 7.2 via the corresponding second contact points 7.12, 7.22. Therefore, a connection between the ground potential 20 and the capacitor 4 is established; the capacitor 2 is grounded.

[0064] The contact module 7 with its access contacts 7.1, 7.2 therefore provides a common contact point for connection to the resistor 3 and the ground potential 20. Both the terminal strip 41 and the movable contact 5.1 designed as a slide rail are moved by the corresponding motor drive 40, 50 in a vertical movement and finally complete the circuit.

[0065] Here, the first switch 4, that is, the terminal strip 41 with the contact teeth 4.1, 4.2 is always actuated before the second switch 5, that is, the first movable contact 5.1. A defined time period is maintained between the actuation of the first switch 4 and the second switch 5, during which the capacitor can be completely discharged. The access contacts 7.1, 7.2 of the terminal strip 7 are preferably designed as elastic contact blades.

[0066] The multi-level converter 1 may have a plurality of capacitors 2. Preferably, each capacitor is respectively equipped with a first switch, a second switch and a resistor. In the case of a plurality of first switches, the first switches are jointly driven or actuated via a first motor drive 40. A plurality of second switches are jointly driven or actuated via a second motor drive 50.

[0067] The motor drives 40, 50 are actuated or controlled via a control device. The control device has a mechanism or is correspondingly designed so that the first motor drive 40 is always actuated and then the second motor drive 50 is actuated. For this purpose, the multi-level converter 1 can have a limit switch, which transmits the actuation of the first and second switches 4, 5 to the control device. The switching sequence of the first and second switches 4, 5 is thus determined.

[0068] In a multi-level converter with multiple batteries 9 and multiple capacitors 2, switches 4 and 5 are present in multiples. The contact module 7 has a pair of separate access contacts 7.1 and 7.2 for each battery 9 or capacitor 2. There is also a pair of contact teeth 4.1 and 4.2 with corresponding contact surfaces. The movable contact 5.1 is designed to be correspondingly sized so that it contacts all access contacts of the multi-level converter and can thus ground multiple batteries 9 together with all capacitors 2.

[0069] Reference numerals list

[0070] 1Multi-level converter

[0071] 2 Capacitors

[0072] 3. Resistors

[0073] 4First switch

[0074] 4.1 First contact tooth

[0075] 4.2 Second contact tooth

[0076] 5 Second switch

[0077] 6.1 First Wire

[0078] 6.2 Second Wire

[0079] 7 contact modules

[0080] 7.1 First access contact

[0081] 7.2 Second access contact

[0082] 7.11 First contact point of first access contact

[0083] 7.21 First contact point of second access contact

[0084] 7.12 Second contact point of first contact point

[0085] 7.22 Second contact point of the second access contact

[0086] 9. Battery

[0087] 10 Shell

[0088] 20 Ground potential

[0089] 40 first motor drive device

[0090] 42 Institutions

[0091] 50 second motor drive device

[0092] 52 institutions.

Claims

1. A multi-level converter (1), the multi-level converter comprising: - Capacitors (2); - Resistors (3); - a first switch (4), which is operated by a first motor drive (40); - a second switch (5), which is operated by a second motor drive (50); wherein: - the first switch (4) connects the capacitor (2) and the resistor (3) in a closed state and short-circuits the capacitor; - The second switch (5) connects the capacitor (2) to ground potential (20) in a closed state.

2. The multi-level converter (1) according to claim 1, wherein: - the first switch (4) comprises first and second contact teeth (4.1, 4.2); - the first and second contact teeth (4.1, 4.2) are electrically conductively connected to the resistor (3); The first contact tooth (4.1), the resistor (3) and the second contact tooth (4.2) form a series circuit.

3. The multi-level converter (1) according to any one of claims 1 to 2, wherein: - the second switch (5) comprises a movable contact (5.1); The movable contact (5.1) is electrically conductively connected to the ground potential (20).

4. The multi-level converter (1) according to any one of claims 1 to 3, wherein: - a contact module (7) having a first access contact (7.1) and a second access contact (7.2); - the first access contact (7.1) has a first contact point (7.11) and a second contact point (7.12); The second access contact (7.2) has a first contact point (7.21) and a second contact point (7.22).

5. The multi-level converter (1) according to any one of claims 1 to 4, wherein: - in the closed state of the first switch (4), the first contact tooth (4.1) contacts the first contact point (7.11) of the first access contact (7.1), and the second contact tooth (4.2) contacts the first contact point (7.21) of the second access contact (7.1), and - In the closed state of the second switch (5), the movable contact (5) contacts the second contact point (7.12) of the first access contact (7.1) and the second contact point (7.22) of the second access contact (7.1).

6. The multi-level converter (1) according to any one of claims 1 to 5, wherein: A battery (9) is provided, and the capacitor (2) is a part of the battery (9).

7. The multi-level converter (1) according to any one of claims 1 to 6, wherein: The battery ( 9 ) can have a plurality of capacitors ( 2 ).

8. The multi-level converter (1) according to any one of claims 1 to 7, wherein: - provided with a plurality of batteries (9); - each battery (9) is respectively assigned a first access contact and respectively assigned a second access contact (7.1, 7.2); - each battery (9) can be discharged via two contact teeth (4.1, 4.2) and a resistor (3); - Each battery (9) can be grounded via a common movable contact (5.1).

9. The multi-level converter (1) according to any one of claims 1 to 8, wherein: - Twelve batteries (9) are provided, and each battery (9) outputs a voltage of 2 kV.

10. The multi-level converter (1) according to any one of claims 1 to 9, wherein: - The multilevel converter operates in the medium voltage range of 20 kV.

11. The multi-level converter (1) according to any one of claims 1 to 10, wherein: Each battery (9) has at least one semiconductor switching element and at least one inductor.

12. Method for disconnecting a multi-level converter (1) according to any one of claims 1 to 11, wherein: - in a first step, the first switch (4) is actuated by a first motor drive (40) and the capacitor (2) is short-circuited by means of a resistor (3); In a second step, the second switch (5) is actuated by the second motor drive (50), thereby connecting the capacitor (2) to ground potential (20); The second step is carried out only when the capacitor (2) has been discharged.

Images