A work machine includes: a controller; a first electrical circuit provided with a first power supply that supplies power to the controller; an electric drive source necessary for operating the work machine; and a second electrical circuit provided with a second power supply that supplies power to the electric drive source. The work machine further includes: a capacitor provided to the second electrical circuit; a first precharge device that performs precharge of the capacitor by using power of the first power supply; and a second precharge device that performs precharge of the capacitor by using power of the second power supply. The controller performs precharge by using one of the precharge devices when it is determined that precharge by using the other one of the precharge devices is impossible.

An electric drive shaft is disclosed including at least one speed-variable generator for generating a voltage with a variable amplitude and a variable frequency, and at least one speed-variable drive motor supplied with the voltage. The drive shaft enables repercussions on the voltage during sudden load changes, and therefore the complexity of the regulation for stabilizing the voltage, to be reduced due to the generator including a supraconductor winding, especially a high-temperature supraconductor winding.

A control unit for a vehicle is configured to control a power-generating unit such that electric power generated by the power-generating unit becomes smaller than that generated when a voltage between terminals of a smoothing capacitor is equal to or larger than an output voltage of a battery, when all of conditions i)-iii) are satisfied, where i) an external power supply unit supplies electric power to the outside in a condition where a shift lever is placed in a parking position, ii) after an amount of electric power stored in the battery is reduced to be smaller than a predetermined power storage amount in a condition where a relay is switched OFF, the relay is operated switch ON, and electric power is generated by the power-generating unit, and iii) the voltage between the terminals of the smoothing capacitor is smaller than the output voltage of the battery.

An ECU performs a controlling process including: switching a main converter to a boost converter CNV2 when a boost converter CNV1 is set as a main converter and when a first stress value Va is greater than a second stress value Vb; switching a sub converter to the boost converter CNV1; switching the main converter to the boost converter CNV1 when the boost converter CNV1 is not set as a main converter, and when the second stress value Vb is greater than the first stress value Va; and switching the sub converter to the boost converter CNV2.

In a diagnostic device, a determiner determines whether a rotational speed of an AC motor is within a low rotational-speed range in which its rotational speed is approximately zero. An input-voltage estimate calculator calculates, as an input-voltage estimate, an estimate of an input voltage to an inverter when it is determined that the rotational speed of the AC motor is within the low rotational-speed range. A malfunction determiner performs a diagnostic task. The diagnostic task calculates an absolute value of a difference between an input-voltage measurement value measured by an input voltage sensor and the input-voltage estimate. The diagnostic task determines whether the absolute value of the difference is higher than a predetermined voltage threshold. The diagnostic task determines that there is a malfunction in the input voltage sensor upon determining that the absolute value of the difference is higher than the predetermined voltage threshold.

A pantograph device of a trolley-type truck includes: a base frame; a bottom frame rockably attached to the base frame; a top frame rockably attached to the vicinity of the top end portion of the bottom frame through a connecting shaft; a collector shoe rockably supported in proximity to the top end portion of the top frame; a hydraulic cylinder for raising and lowering the bottom frame, attached to the base frame; and a spring which acts so as to rotate the top frame upward through the connecting shaft. By erecting the bottom frame by the hydraulic cylinder, the tensile force produced in the spring is increased and the top frame is rotated upward through the connecting shaft. This makes it possible to obtain a wide movable range without use of a long and strong spring and enhance the followability to overhead wires without increasing pressing force.

The present disclosure relates to electrical systems in general and embodiments of the teachings may include stabilization circuits for a vehicle electrical system comprising: a first connection for a first electrical system branch; a second connection for a pole of a first energy store of the first electrical system branch; a third connection for a second electrical system branch; a fourth connection for a third electrical system branch; a grounding connection for connection of the stabilization circuit to ground; a second energy store; a third energy store; a serial disconnection switch element between the second connection and the grounding connection; and a decoupling switch element connecting the first connection to the fourth connection. The second energy store is connected between the grounding connection and the third connection. The third connection is connected via the third energy store and a first converter to the fourth connection.

Inverterless running control is control in which an inverter is set to a gate cut-off state, an engine is driven to mechanically rotate a motor-generator and to generate in the motor-generator, counter-electromotive torque in accordance with a difference between a counter-electromotive voltage of the motor-generator and a system voltage, and a vehicle runs with drive torque applied to an output shaft as reaction force of the counter-electromotive torque. An ECU controls drive torque to produce driving force determined by an accelerator position by raising or lowering the system voltage during inverterless running control.

The invention relates to supplying electric traction motors of a rail vehicle with electrical energy. Internal combustion engine/machine combination are operated such that alternating current is generated and used for operating at least one electric traction motor, in a first operating state of the machine in a generator mode. In a second operating state of the machine, an associated machine converter supplies alternating current and drives the associated internal combustion engine, wherein at least the machine converter associated with the second electrical machine is supplied, while the associated electrical machine is in the second operating state, via an electrical DC voltage line with direct current by a rectifier associated with the first machine, wherein the rectifier produces the direct current from alternating current generated by the first electrical machine.

An electrical system architecture for a mobile, electric hybrid machine includes a first bus configured to receive electric power at a first, selectively adjustable voltage from an electrical power source. A second bus is configured to receive electric power at a second voltage that is lower than the first voltage. A controller is configured to determine a desired magnitude of the second voltage for the second bus, produce a signal indicative of a magnitude of the first, selectively adjustable voltage that is a multiple of the desired magnitude of the second voltage, and adjust the magnitude of the first voltage in the first bus to the multiple of the desired magnitude of the second voltage. A fixed-ratio power converter is configured to convert the power at the first voltage in the first bus to the power at the second voltage in the second bus.