A power device includes one or more electrical components, the electrical components including one or more physical attribute. The power device includes one or more sensors configured to monitor the attribute(s). The power device includes a non-transitory computer-readable storage medium including one or more alerting rule. The power device includes one or more processors configured for retrieving the one or more alerting rule from the storage medium. The processors are configured for monitoring one or more sensor value from the sensor(s), wherein the sensor values are associated with the attribute(s). The processors are configured for evaluating the at least one alerting rule during the monitoring, and when the one or more alerting rule results in a pending failure condition, sending a notification to a user.

The invention relates to a method, electrical circuit arrangements and insulation monitoring devices for an interference-resistant insulation monitoring of an ungrounded power supply system having a converter. Switching-frequent interfering signals, which are caused by operating the converter, are identified and assessed in a measured displacement voltage independently of the detection of a measuring signal in order to derive a switching (off) signal if required. Complementary thereto, an interfering resistance with respect to low-frequency interfering portions generated by the converter is attained by these low-frequency interfering portions being generated from a replica of a pulse width modulation signal of the converter and being suppressed sufficiently via subtraction that a monitoring without gaps (frequency) of the insulation resistance becomes possible.

The invention relates to an elevator comprising at least one elevator car moved by at least one elevator motor, which elevator motor is driven by a frequency converter controlled by a control device of the elevator, the frequency converter comprising a rectifier bridge, an inverter bridge and a DC link connected in-between, the inverter bridge being connected to the elevator motor and the rectifier bridge being connected to AC mains via three phase supply lines comprising an LCL-filter and a mains switch. The elevator further comprises a backup power supply and a safety device of the control device, which in case of a mains power failure is configured to switch off the mains switch and to connect the backup power supply to the DC link and/or to at least one phase supply line, whereby the rectifier bridge is a bidirectional rectifier bridge being configured to convert DC supplied to the DC link from the backup power supply to an AC voltage supplied to at least two of the phase supply lines connected with at least one load circuit. An earth fault protection circuit for the load circuit is connected between earth and a common terminal of the capacitors of the LCL filter for monitoring an earth fault indicating signal, and which earth fault protection circuit is configured to issue an earth fault signal and/or initiating earth fault safety measures, dependent on the earth fault indicating signal.

A ground fault detection method for a power converter is provided, including: measuring, by a voltage sensor, a first voltage and a second voltage respectively, and converting the first voltage and the second voltage into a first digital voltage signal and a second digital voltage signal; receiving, by a controller, the first digital voltage signal and the second digital voltage signal, extracting a corresponding feature quantity of the first voltage and a corresponding feature quantity of the second voltage according to the first digital voltage signal and the second digital voltage signal; and further determining a type of the ground fault of the power converter and locating a ground fault; and when the power converter has a ground fault, shutting down the power converter.

A matrix converter includes one or more current sensors structured to sense current flowing through the matrix converter, a matrix of switches including a number of solid state transistors, and a control circuit structured to detect faults in power flowing through the matrix converter based on the sensed current, to control the matrix of switches to drive an external device, and to control the matrix of switches to switch to prevent power from flowing internal to the matrix converter, or external to the external device in response to detecting a fault in power flowing through the matrix converter.

The present invention discloses a system for limiting a peak current of short-circuit current, which comprises a first a first high-frequency branch configured to provide a first high-frequency current to a first switch (1SKa) of a first phase branch of a three-phase AC when the first phase branch occurs a short-circuit, wherein the first high-frequency current is configured to cause a zero-crossing point of a short-circuit current to appear before a zero-crossing point of the three-phase AC; a second high-frequency branch configured to provide a second high-frequency current to a second switch (1SKc) of a second phase branch of the three-phase AC when the second phase branch occurs a short-circuit, wherein the second high-frequency current is configured to cause a zero-crossing point of a short-circuit current to appear before a zero-crossing point of the three-phase AC, a third phase branch of the three-phase AC connected in parallel with the first phase branch and the second phase branch and configured to always supply power. The present invention superimposes the high-frequency current on the original short-circuit current of the switch, thereby the total time from the arc generation to extinction at the zero-crossing point and then to the judgement by the control system is shorter than the time that the short-circuit current peak appears. Therefore, it can effectively lower the damage of the short-circuit current peak to the dynamic stability of the switch and lower the impact on system equipment.

A power device includes one or more electrical components, the electrical components including one or more physical attribute. The power device includes one or more sensors configured to monitor the attribute(s). The power device includes a non-transitory computer-readable storage medium including one or more alerting rule. The power device includes one or more processors configured for retrieving the one or more alerting rule from the storage medium. The processors are configured for monitoring one or more sensor value from the sensor(s), wherein the sensor values are associated with the attribute(s). The processors are configured for evaluating the at least one alerting rule during the monitoring, and when the one or more alerting rule results in a pending failure condition, sending a notification to a user.

A system for limiting a peak current of short-circuit current comprises a first high-frequency branch configured to provide a first high-frequency current to a first switch (1SKa) of a first phase branch of a three-phase AC when the first phase branch occurs a short-circuit; a second high-frequency branch configured to provide a second high-frequency current to a second switch (1SKc) of a second phase branch of the three-phase AC when the second phase branch occurs a short-circuit; and a third phase branch of the three-phase AC connected in parallel with the first phase branch and the second phase branch and configured to always supply power.

A power conversion circuit having a solid-state circuit breaker integrated therein is disclosed. With a disconnect switch between a utility source and the power conversion apparatus described for meeting UL489, the power conversion circuit includes an input connectable to an AC source, a rectifier circuit connected to the input to convert an AC power input to a DC power, and a DC link coupled to the rectifier circuit to receive the DC power therefrom. The rectifier circuit comprises a plurality of phase legs each including thereon an upper switching unit and a lower switching unit, wherein at least one of the upper and lower switching units on each phase leg comprises a bi-directional switching unit that selectively controls current and withstands voltage in both directions, so as to provide a circuit breaking capability that selectively interrupts current flow through the rectifier circuit, while maintaining original power conversion functionalities.

Apparatus and methods for supplying DC power to control circuitry of a matrix converter is provided. In certain embodiments, a matrix converter includes an array of switches having AC inputs for receiving a multi-phase AC input voltage and AC outputs for providing a multi-phase AC output voltage to a load, such as an electric motor. The matrix converter further includes control circuitry for opening or closing individual switches of the array, and a clamp circuit connected between the AC inputs and AC outputs of the array and operable to dissipate energy of the load in response to an overvoltage condition, such as an overvoltage condition arising during shutdown. The clamp circuit includes a switched mode power supply operable to generate a DC supply voltage for the control circuitry.