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DE-102024210886-A1 - Power electronic switch

DE102024210886A1DE 102024210886 A1DE102024210886 A1DE 102024210886A1DE-102024210886-A1

Abstract

The invention relates to a switching-current circuit breaker (SSCB) for switching or interrupting a power supply, which is formed with at least one switching transistor (3) and an energy absorber (2) arranged in parallel to the at least one switching transistor (3). According to the invention, the SSCB includes a leakage current measuring circuit (5) which is arranged in series with the energy absorber (2). The SSCB allows the monitoring of the energy absorber for age-related functional defects and thus ensures safe operation.

Inventors

  • Karsten Handt
  • HAUKE NANNEN

Assignees

  • SIEMENS AKTIENGESELLSCHAFT

Dates

Publication Date
20260513
Application Date
20241113

Claims (10)

  1. SSCB for switching or interrupting a power supply, comprising at least one switching transistor (3) and an energy absorber (2) arranged in parallel to the at least one switching transistor (3), characterized in that the SSCB comprises a leakage current measuring circuit (5) which is arranged in series with the energy absorber (2).
  2. SSCB after Claim 1 , characterized in that the leakage current measuring circuit (5) is formed with a bypass path (8) which includes a voltage-dependent resistance element (10) and a measuring path (9) which are arranged parallel to each other.
  3. SSCB after Claim 2 , characterized in that the voltage-dependent resistive element (10) is a metal oxide varistor, a TVS diode, an RC circuit or a combination thereof.
  4. SSCB after one of the Claims 1 until 3 , characterized in that the SSCB is formed with an optocoupler (6) and is designed for the transmission of leakage current information obtained by means of the leakage current measuring circuit (5) to an evaluation device (7) using the optocoupler (6), wherein the primary side of the optocoupler (6) is integrated into the leakage current measuring circuit (5).
  5. SSCB after one of the Claims 2 until 4 , characterized in that the primary side of the optocoupler (6) is arranged parallel to the measurement path (9).
  6. SSCB after Claim 5 , characterized in that the optocoupler is protected against excessively high voltages by means of a protective circuit.
  7. SSCB after one of the Claims 2 until 6 characterized in that the SSCB includes an evaluation unit which checks leakage current information regarding compliance with a criterion and, if necessary, generates a warning message.
  8. SSCB after Claim 7 , characterized in that - the SSCB comprises a measuring sensor for measuring the voltage drop (Ucb) across the at least one switching transistor and is designed to transmit the measured voltage drop (Ucb) to the evaluation unit, and - the evaluation unit is configured to use a criterion dependent on this voltage drop (Ucb).
  9. SSCB after one of the Claims 2 until 8 , characterized in that - the energy absorber (2) is formed with at least one resistance element, and - this at least one resistance element is dimensioned larger than the voltage-dependent resistance element (10) of the leakage current measuring circuit (5), so that on the one hand the voltage supply of the leakage current measuring circuit (5) is ensured, and on the other hand no excessively high loads occur for elements of the leakage current measuring circuit (5) during normal operation.
  10. SSCB after one of the previous Claims 2 until 9 , characterized in that the energy absorber (2) is formed with a MOV and the voltage-dependent resistance element (10) is designed for a slower aging in comparison to the MOV.

Description

The invention relates to a solid state circuit breaker. Advances in the development of semiconductor devices have led to new switching concepts that can replace conventional, typically electromechanical switches, particularly in low-voltage applications. These new concepts apply, for example, to circuit breakers or motor starters, but can also be used, in principle, for switching higher currents, such as with power switches. The fast response times of the semiconductor devices are of central importance, as they prevent damage from overload. This means the switch interrupts the current before damage occurs to the installation or the equipment used, or before the semiconductor components of the protective device itself could be destroyed as a self-protection measure. In semiconductor-based protective devices, also known as solid-state circuit breakers (SSCBs), the switching energy is not converted into an arc as in a mechanical switch, but rather into heat via an additional circuit called an energy absorber. During disconnection, the disconnection energy comprises the energy stored in the circuit, i.e., in the network, line, or load impedances (consumer impedances). To relieve the energy absorber, the current flowing at the moment of disconnection must be as low as possible. This also applies in the case of a short circuit, where the current rises very rapidly. Rapid short-circuit detection allows for early detection of a short circuit and prevents excessively high short-circuit currents. During a disconnection process, the semiconductor-based protective device interrupts the circuit almost instantaneously, within microseconds. High currents do not occur, and the load on the energy absorber of a semiconductor-based protective device is reduced. Known methods for short-circuit detection or shutdown criteria are usually based on determining and evaluating the actual current value. Solid-state switches (SSCBs) typically consist of a power electronic switch (LE switch, e.g., IGBT, MOSFET, JFET, etc.) and a power absorber (e.g., TVS diode, MOV, RC circuits, and combinations thereof). Particularly with MOVs (metal oxide varistors), an aging process can occur during operation, altering their electrical properties. The operating voltage, or reverse voltage, at which the varistor can be safely operated continuously, often decreases. This decrease in operating voltage leads to an increase in leakage current, which, combined with the applied voltage, causes the component to heat up. In the long term, this leads to component failure, and the solid-state switch would no longer be able to reliably interrupt the circuit. In the worst case, heating leads to the complete thermal destruction of the component, which can endanger nearby equipment and systems, and in the worst case, endanger people. The invention aims to increase the safety of SSCBs. The problem is solved by an SSCB according to claim 1. Advantageous further developments are specified in the dependent claims. The SSCB according to the invention is designed for switching or interrupting a power supply. It comprises at least one switching transistor or power semiconductor (e.g., two antiparallel power semiconductors for a bidirectional SSCB) and an energy absorber arranged in parallel to the at least one switching transistor. Additionally, the SSCB includes a leakage current measuring circuit, which is arranged in series with the energy absorber (and thus also in parallel with the at least one switching transistor). The term SSCB, or power electronic switch, refers to any switch designed to interrupt an electrical circuit using a switching transistor or power semiconductor. Examples include circuit breakers, power switches, contactors, and starters. The switch may also include an electromechanical disconnect device, which may be required by standards or be part of the switching concept (e.g., in hybrid switching architectures). The switch allows the energy absorber to be monitored for age-related malfunctions, thus ensuring the safe operation of the SSCB. According to a further development of the SSCB according to the invention, the leakage current measuring circuit is formed with a bypass path, which includes a voltage-dependent resistor element, and a measuring path, which are arranged in parallel to each other. "Voltage-dependent resistor element" refers to a component or combination of components which are designed to change the resistance appropriately. Typically, this involves a reduction in resistance under critical conditions that are detrimental to the components used (high voltages). In the case of the voltage-dependent The resistive element is, for example, a metal oxide varistor, a TVS diode, an RC circuit, or a combination thereof. According to one embodiment, the SSCB according to the invention is formed with an optocoupler and configured for transmitting leakage current information obtained by means of the leakage current measuring circuit to an eval