Abstract:
The invention describes a method for the computer-assisted operation of an electric motor (M) which is exposed to a thermal load as a result of the rotational motion of its rotor (T) during operation. In this method, measured data is received during the operation of the electric motor (M). One or more temperature values are derived from the measured data. A number of temperature characteristics curves (TPi) are then forecast with differing restart times (t(TPi)) for defining a cooling period for reducing the thermal load on the electric motor (M), wherein the approximated temperature value, which results from the approximated temperature value is used as the specific starting value for a restart in the temperature characteristics curve (TPi) to be forecast. The temperature characteristics curve (TPi) lying in the past is visualised together with the number of forecast temperature characteristics curves (TPi) in a time-temperature graph, wherein the number of forecast temperature characteristics curves (TPi) represents a possible restart of the electric motor (M) at the particular restart time (t(TPi)) with the starting value determined in each case. A quality metric (GM) is determined for each of the number of forecast temperature characteristics curves (TPi). Finally, the quality metrics (GM) are mapped on a colour scale (20), which is visually output on a user interface, wherein, in response to a user interaction input via the user interface (13), time information for the restart of the electric motor (M) is output.
Abstract:
A method and apparatus is described in which a series of short-circuiting pulses is applied to a motor. A current in the motor is determined after one or more of the series of short circuit pulses has completed. The duration of the short-circuit pulses is adjusted depending on the determined current. The method and apparatus may be used within an arrangement for catching a spinning motor.
Abstract:
A system and method for estimating operating characteristics of an induction motor is disclosed. The system includes a motor control device that is electrically connectable between a motor and a power source. The motor control device includes a plurality of switching devices comprising at least one thyristor corresponding to a respective phase of the motor. The motor control device also includes a controller programmed to disconnect the power source from the motor for a predetermined time period following a first plurality of cycles of a mains phase voltage of the power source. The controller is further programmed to measure a back-emf voltage during the predetermined time period, estimate an operating characteristic of the motor from the measured back-emf voltage, and trigger the plurality of switching devices to reconnect the power source to the motor following estimation of the operating characteristic.
Abstract:
Methods, systems, and computer readable media for adaptive out of step protection for power generators with load resynchronization capability are disclosed. According to one method, when a fault condition occurs in a load being supplied by a power generator, a number of pole slips expected to occur in the generator due to the fault before resynchronization is estimated. It is determined whether the estimated number of pole slips exceeds a threshold. An offline or online status of the generator is controlled based on the determination as to whether the estimated number of pole slips exceeds the threshold.
Abstract:
In one embodiment of the present invention, a system for ride-through of an adjustable speed drive for voltage sags is provided. The system comprises an adjustable speed drive including a three phase electric utility, a diode rectifier, a dc-link, an inverter, and a motor. Coupled to the adjustable speed drive is a ride-through circuit which includes a controller having a first input and a second input, the first input operable to receive the voltage from each phase of the three phase electric utility and determine the magnitude and phase of the voltage sag, and the second input operable to receive the dc-link voltage to ensure that the rated dc-link voltage is not exceeded. Also included is an IGBT coupled to an output of the controller and operable to switch on and off rapidly based on the amount of voltage sag. An inductor associated with the IGBT and operable to store energy when the IGBT is switched on and to transfer energy to the dc-link when the IGBT is off is also included. This maintains the dc-link voltage to provide ride-through operation of the adjustable speed drive.
Abstract:
A method of starting a BLDC motor may include maintaining all power stage transistors in an off state during a motor startup check responsive to activation of a start switch, determining, prior to motor startup, motor state information including information indicative of whether the BLDC motor is rotating and, if rotating, speed of rotation, and employing a selected one of at least two startup procedures including a first start procedure and a second startup procedure based on the motor state information.
Abstract:
The present invention relates to a motor controller employing bootstrap- capacitor supplies and in particular to the situation where the bootstrap supplies have to be charged, while the motor controller is connected to a spinning and energized motor. The present invention introduces a method of recharging based on choosing a recharging sequence from a set of recharging sequences, where the choice depends on the state of the connected motor and in particular on the back-EMF voltages of the motor.