A motor drive device for driving a motor, which has a plurality of winding pairs, includes a plurality of inverter units for the plurality of winding pairs. The inverter units are coupled in parallel to a power source. A plurality of capacitors provided for the plurality of inverter units, and a plurality of power relays are disposed between the power supply and the inverter units. In particular, a power relay is provided for each of the inverter units. A control unit detects a short failure of the power relay, and simultaneously turns ON the power relays that do not have a short failure. In such manner, damage to the power relays as well as damage to other electronic components of the motor driver device due to a large electric current is prevented.

An inverter protection device is disclosed. An inverter protection device, which determines whether or not a pulse-width modulation (PWM) control signal provided to an inverter unit of an inverter is blocked in accordance with a voltage signal received from first and second switches of a safety relay which are parallelly connected, comprises: a first power switch which is switched to an on-state by means of a first voltage signal applied from the first switch; a second power switch which is switched to an on-state by means of a second voltage signal applied from the second switch; and a buffer unit which is on-off controlled in accordance with an output current of the first and second power switches and provides the PWM control signal to the inverter unit.

An electrical system forming part of a solar power plant is described. The electrical system includes a plurality of photovoltaic (PV) panels, a power converter, and a controller. In response to a detected electric arc on the DC side of the power converter, the controller is configured to enable a short circuit state of the power converter by controlling semiconductor switches of the power converter (e.g., turning on some or all of the semiconductor switches) to create a short circuit between DC input terminals of the power converter. The short circuit path though the power converter will extinguish the detected electric arc in the connected DC circuit.

A power converter and method for providing surge protection to the power converter is provided herein. An over voltage protection portion of a protection circuit is coupled between the rail voltage and ground reference of the power converter, and senses a first magnitude of the rail voltage. An under voltage protection portion of the protection circuit is coupled to a controller of the power converter and further between the rail voltage and the ground reference, and senses a second magnitude of the rail voltage to be transmitted to the controller. A regulator block is coupled between the over voltage protection portion and the under voltage protection portion, and is configured to compare the first magnitude of the rail voltage to a reference voltage of the regulator block, and to short circuit the under voltage protection portion when the first magnitude of the rail voltage is greater than the reference voltage.

A device (9) for protecting a direct current electrical system (1) having one or more modules (2) from electric arcs comprises: a first sensor (10) provided with a first ring of ferromagnetic material configured to generate a first signal, representing a oscillating component of a current flowing through a cable inserted into the ring; a conditioning stage (12), having a bandpass filter, for conditioning the first signal; a first threshold comparator (13); a counter (15); a processor (14); a second sensor (19), configured to generate a second signal representing a direct current component of the current flowing through the cable; a second threshold comparator (20).

An electrical apparatus configured to electrically connect to a multi-phase alternating current (AC) electrical power distribution network includes: an input electrical network including: a plurality of input nodes, each configured to electrically connect to one phase of the multi-phase AC electrical power distribution network; at least one non-linear electronic component electrically connected to the input electrical network; an impedance network electrically connected between the input electrical network and ground; and a control system configured to: access a voltage signal that represents a voltage over time at the input electrical network; determine a frequency content of the voltage signal; determine a property of the frequency content; and determine whether an input current performance condition exists in the electrical apparatus based the property of the frequency content.

An electrical apparatus configured to electrically connect to a multi-phase alternating current (AC) electrical power distribution network includes: an input electrical network including: a plurality of input nodes, each configured to electrically connect to one phase of the multi-phase AC electrical power distribution network; at least one non-linear electronic component electrically connected to the input electrical network; an impedance network electrically connected between the input electrical network and ground; and a control system configured to: access a voltage signal that represents a voltage over time at the input electrical network; determine a frequency content of the voltage signal; determine a property of the frequency content; and determine whether an input current performance condition exists in the electrical apparatus based the property of the frequency content.

A solid-state magnet control unit includes a housing and magnet controller circuitry mounted within the housing. The magnet controller circuitry controls current passing through a magnet. The magnet controller circuitry includes a power storage unit, drivers in a bridge network, e.g., an insulated gate bipolar transistor (IGBT) in a bridge network, and dump circuitry. The dump circuitry limits circuit damage to the magnet controller circuitry and other components contained within the magnet control unit. When the dump driver is not operational, operation of the magnet control unit is automatically switched to first or second safety mode of operation.

An electrical apparatus configured to electrically connect to a multi-phase alternating current (AC) electrical power distribution network includes: an input electrical network including: a plurality of input nodes, each configured to electrically connect to one phase of the multi-phase AC electrical power distribution network; at least one non-linear electronic component electrically connected to the input electrical network; an impedance network electrically connected between the input electrical network and ground; and a control system configured to: access a voltage signal that represents a voltage over time at the input electrical network; determine a frequency content of the voltage signal; determine a property of the frequency content; and determine whether an input current performance condition exists in the electrical apparatus based the property of the frequency content.

A photovoltaic power generation system includes an inverter, a controller, and at least two direct current branch circuits. The leakage current detection apparatus is configured to: detect a leakage current of the direct current branch circuit on which the leakage current detection apparatus is located and send the leakage current to the controller. The controller is further configured to: when the photovoltaic power generation system runs and a value of a leakage current of the direct current branch circuit exceeds a preset range, determine that an insulation fault occurs on the direct current branch circuit. The system can determine the direct current branch circuit on which the insulation fault occurs in the photovoltaic power generation system, so that measures are taken in time for the direct current branch circuit on which the insulation fault occurs, to eliminate a potential safety hazard.