Rise time

About: Rise time is a research topic. Over the lifetime, 4748 publications have been published within this topic receiving 47512 citations.

Swing control device and construction machinery

Abstract: In a swing control device installed in an electric rotary excavator (a construction machine), when a leading edge or a trailing edge of a lever signal is sharp due to a quick operation of a swing lever, a gradient as a rise time Ta1 or a fall time Tb1 is provided to the leading edge or the trailing edge of the torque output and the acceleration that are output based on the lever signal so as to somewhat ease the edge. With the arrangement, an impact in acceleration or deceleration of a rotary body can be suppressed. Specifically, a gradient in the acceleration operation is provided such that the rise time Ta1 becomes 0.15 seconds or more, while a gradient in the stop deceleration operation is provided such that the fall time Tb1 becomes 0.1 seconds or more.

Sensorless speed measurement for brushed DC motors

Abstract: This study describes two new methods of sensing the speed of a pulse-width modulation-driven brushed DC motor based on measuring the inductive spikes generated when the motor is turned off. The research has studied the relationship between the rise time or duration of the inductive spike, and the motor current and speed. Computationally inexpensive algorithms have been developed that use either rise time or duration to estimate speed. The algorithms have been implemented on an inexpensive microprocessor and show a speed error of approximately 10% over most of the motor's range of operation. The spike rise time implementation requires an analog-to-digital converter (ADC) as found in many microprocessors, while the spike duration implementation requires only a single digital input thus reducing the cost of the controlling microprocessor. This work has shown that sensorless speed measurement can be based on the inductive spike and has also raised future research questions, such as to the best way to optimise the speed measurement in dynamic situations, and measurement errors to be expected in a mass production environment.

Electrical treeing in silicone gel under repetitive voltage impulses

Abstract: Silicone gel is widely used to encapsulate power electronic modules. The weakness of the electrical insulation is surface discharges initiated at the gel-substrate-electrode triple junction and the subsequent formation of cavities; so called electrical trees. The propagation characteristics of cavities under high frequency and fast rise time voltages, which are typical waveforms formed in power electronic modules, have not been fully understood. Thus, in this research, the influence of frequency, rise time, and polarity on electrical treeing under repetitive voltage impulses are investigated. The results show that discharge tracks under positive impulses have filamentary shapes, and discharge tracks under negative impulses have spindle-shapes. The cavity length increases with the frequency and is especially long when the rise time is short under high frequency. This indicates the importance of understanding the cavity propagation characteristics under actual voltage waveforms in power electronics modules.