Speed Torque characteristics of Brushless DC motor in either direction on load using ARM controller

This paper presents the speed torque characteristics of BLDC motor on load in forward and reverse direction. The Hall sensors of the BLDC motor is bestowed as the input to the ARM controller. The PWMs are produced depending upon the input of the controller. In order to convert DC to three phase AC, three phase bridge inverter with MOSFET as switches is used. The generated PWMs are inputted to the gate of the MOSFETs in the inverter. The output of the inverter is the energization sequence of BLDC motor and only two phases energizes at once. Dynamometer is used for encumbering the motor. The results are acquired for variable load torque and Speed torque characteristics are observed. Keywords: BLDC motor, PWM, MOSFET and dynamometer

Low Voltage Firing Characteristics of a Simple Triggered Vacuum Gap

The firing characteristics of the simple triggered vacuum gap (TVG) using lead zirconate titanate as dielectric material in the triggered gap are described. This TVG has a long life of about 2000 firings without appreciable deterioration of the electrical properties for main discharge currents upto 3 kA and is much superior to these made with Supramica (Mycalex Corporation of America) and silicon carbide as used in our earlier investigations. The effects of the variation of trigger voltage, trigger curcit, trigger pulse duration, trigger pulse energy, main gap voltage, main gap separation and main circuit energy on the firing characteristics have been studied. Trigger resistance progressively decreases with the number of firings of the trigger gap and as well as of the main gap. This decrease in the trigger resistance is more pronounced for main discharge currents exceeding 10 kA. The minimum trigger current required for reliable firing decreases with increase of trigger voltage upto a threshold value of 1.2 kV and there-onwards saturates at 3.0 A. This value is less than that obtained with Supramica as dielectric material. One hundred percent firing probability of the TVG at main gap voltages as low as 50 V is possible and this low voltage breakdown of the main gap appears to be similar to the breakdown at low pressures between moving plasma by other workers. and the cold electrodes immersed in it, as reported

Low-voltage and high-current delay characteristics of a simple triggered vacuum gap

Low-voltage and high-current switching delay characteristics of a simple triggered vacuum gap (TVG) are described using lead zirconate titanate as the dielectric material in the auxiliary gap. This TVG has superior performance at high currents (up to 14 kA was studied) with regard to delay, reliable firing and extended life as compared to the one using either supramica or silicon carbide. The total delay consists of three intervals: to break down the auxiliary gap, to propagate the trigger plasma and to break down the main gap. The data on the influence of the various parameters like the trigger voltage, current, energy and the main circuit energy are given. It has been found that the delay due to the first two intervals is small compared to the third

Delay characteristics of a simple triggered vacuum gap

Firing delays of a simple triggered vacuum gap are reported in this paper. The effects of insulating materials in the auxiliary gap, auxiliary gap current, main gap current and electrode separation on the delay have been investigated. The presence of insulating material in the auxiliary gap having low auxiliary gap resistance appears to exhibit large delay. Delay decreases considerably with increase of current in the auxiliary and the main gaps, but it increases with increase of electrode separation. The scatter in the delay is less than 25 ps and 500 ps with supramica (Mycalex Corporation of America) and silicon carbide respectively at lower values of auxiliary gap current and it becomes negligible for supramica at auxiliary gap currents greater than 6A. This investigation appears to indicate that the simple device can be used as a fast switch

Anode Phenomena in Triggered Vacuum Gaps

Arc voltage - current characteristics and threshold current densities occuring during the formation of anode spots in triggered vacuum gaps are reported. Single pulses of 1.65 ms arcing time, which correspond to switching surge currents, are used in the study with copper and aluminum anodes. The threshold values are 1.75 times the values reported earlier using the longer, 8 mis, arcing time. They are found to depend upon the duration of arcing time as well as upon electrode material, surface conditions, electrode size and contact separation. Lateral inhomogenity in the electrode geometry appears to reduce the threshold value by promoting early formation of anode spots

Simulation of DTC-CBSVPWM fed SPMSM Drive with Five-level Diode Clamped Inverter

In this paper a simulation analysis of DTC-CBSVPWM of SPMSM drive using five-level diode clamped inverter is analyzed. It has simple structure and provides dynamic behavior comparable with classical DTC. Direct Torque Control (DTC) is an accurate controller for permanent magnet synchronous motor (PMSM) due to its robust and fast torque response in steady-state and transient operating condition. However, the main disadvantage of DTC is high ripples in stator current, flux linkage and torque due to the application of same active voltage vector during the whole sample period and possibly several consecutive sample intervals. This can be overcome by using proper modulation technique. Space Vector Modulation (SVM) which synthesizes any voltage vector lying inside the sextant gives good performance, but however the complexity involved is more in calculating angle and sector. To reduce the complexity involved in SVPWM, a novel modulation technique named Unified voltage modulation or carrier based space vector pulse width modulation (CBSVPWM) is described using the concept of effective time. By using this method the inverter output voltage is directly synthesized by the effective times and the voltage modulation task can be greatly simplified. The actual gating signals for each inverter arm can be easily deduced as a simple form using the effective time relocation algorithm