A motor inverter includes an inverter circuit having a plurality of switching elements, a capacitor, a precharge closing an opening and closing part, a controller closing the opening and closing part in response to the ON operation of the operational switch, wherein when charge is accumulated in the capacitor until voltage of the capacitor reaches a predetermined voltage value capable of determining whether or not short circuiting occurs, the controller controls a switching operation of the switching elements, and a determiner determining whether or not short circuiting occurs based on at least one of current flowing in the inverter circuit and voltage of the capacitor when the controller controls the switching operation of the switching elements in a state that the electric charge is accumulated in the capacitor and the opening and closing part is opened.

A motor inverter includes an inverter circuit having a plurality of switching elements, a capacitor, a precharge closing an opening and closing part, a controller closing the opening and closing part in response to the ON operation of the operational switch, wherein when charge is accumulated in the capacitor until voltage of the capacitor reaches a predetermined voltage value capable of determining whether or not short circuiting occurs, the controller controls a switching operation of the switching elements, and a determiner determining whether or not short circuiting occurs based on at least one of current flowing in the inverter circuit and voltage of the capacitor when the controller controls the switching operation of the switching elements in a state that the electric charge is accumulated in the capacitor and the opening and closing part is opened.

A power device includes a semiconductor relay and a pre-charger that has a reference voltage generator and a controller. The semiconductor relay is disposed at a position between a battery supplying electric power to a power converter that serves as a load and a smoothing capacitor connected on a battery side of the power converter in parallel with the power converter. The reference voltage generator generates a reference voltage having a gradually-increasing voltage value in a pre-charge period, prior to a turning ON of the semiconductor relay accompanying a turning ON of an ignition switch. The controller controls the semiconductor relay such that a charge voltage which is an inter-terminal voltage of the smoothing capacitor is set to a preset value according to the reference voltage.

A power device includes a semiconductor relay and a pre-charger that has a reference voltage generator and a controller. The semiconductor relay is disposed at a position between a battery supplying electric power to a power converter that serves as a load and a smoothing capacitor connected on a battery side of the power converter in parallel with the power converter. The reference voltage generator generates a reference voltage having a gradually-increasing voltage value in a pre-charge period, prior to a turning ON of the semiconductor relay accompanying a turning ON of an ignition switch. The controller controls the semiconductor relay such that a charge voltage which is an inter-terminal voltage of the smoothing capacitor is set to a preset value according to the reference voltage.

A motor inverter includes an inverter circuit having a plurality of switching elements, a capacitor, a precharge closing an opening and closing part, a controller closing the opening and closing part in response to the ON operation of the operational switch, wherein when charge is accumulated in the capacitor until voltage of the capacitor reaches a predetermined voltage value capable of determining whether or not short circuiting occurs, the controller controls a switching operation of the switching elements, and a determiner determining whether or not short circuiting occurs based on at least one of current flowing in the inverter circuit and voltage of the capacitor when the controller controls the switching operation of the switching elements in a state that the electric charge is accumulated in the capacitor and the opening and closing part is opened.

A motor inverter includes an inverter circuit having a plurality of switching elements, a capacitor, a precharge closing an opening and closing part, a controller closing the opening and closing part in response to the ON operation of the operational switch, wherein when charge is accumulated in the capacitor until voltage of the capacitor reaches a predetermined voltage value capable of determining whether or not short circuiting occurs, the controller controls a switching operation of the switching elements, and a determiner determining whether or not short circuiting occurs based on at least one of current flowing in the inverter circuit and voltage of the capacitor when the controller controls the switching operation of the switching elements in a state that the electric charge is accumulated in the capacitor and the opening and closing part is opened.

A frequency converter, includes: a DC link, wherein the DC link has a first connection pole at which a positive link potential is present during operation of the frequency converter, and a second connection pole at which a negative link potential is present during operation of the frequency converter; an inverter, wherein the inverter has a first connection pole at which a positive inverter potential is present during operation of the frequency converter, and a second connection pole at which a negative inverter potential is present during operation of the frequency converter; a resistive shunt which is looped in between the first connection pole of the DC link and the first connection pole of the inverter; a differential amplifier which is designed to generate a test voltage from a potential difference across the resistive shunt; and an evaluation unit which is designed to detect a ground fault based on the test voltage.

A frequency converter, includes: a DC link, wherein the DC link has a first connection pole at which a positive link potential is present during operation of the frequency converter, and a second connection pole at which a negative link potential is present during operation of the frequency converter; an inverter, wherein the inverter has a first connection pole at which a positive inverter potential is present during operation of the frequency converter, and a second connection pole at which a negative inverter potential is present during operation of the frequency converter; a resistive shunt which is looped in between the first connection pole of the DC link and the first connection pole of the inverter; a differential amplifier which is designed to generate a test voltage from a potential difference across the resistive shunt; and an evaluation unit which is designed to detect a ground fault based on the test voltage.

A method for flying start control of a motor, a computer readable medium, and a power conversion system having an inverter and a controller configured by computer executable instructions in a memory to perform flying start of a rotating motor by field weakening control to control the motor responsive to the motor speed exceeding the rated speed or other non-zero threshold at startup of the power conversion system. The method includes measuring a motor speed of a motor, responsive to startup of a power conversion system, and performing a flying start operation using field weakening control to control the motor responsive to the motor speed exceeding a non-zero threshold at startup of the power conversion system.

An example converter for a switched reluctance (SR) generator includes one or more gate driver circuits that are not only used to synchronously control switches, such as insulated gate bipolar transistors (IGBTs) of the converter, but also used to provide priming function during start-up of the generator. Since, an SR generator does not have to ability to self provide magnetic flux, priming current is provided to coils of the SR generator to initiate a magnetic flux. By using the gate drive circuit to provide the priming current, an additional priming circuit is not required. As a result, the converter design is more streamlined, with reduced complexity, cost, and size. When a bus voltage of the converter is below a threshold level, the one or more gate drive circuits can provide the priming current on the bus to initiate the SR generator.