The chopper converts the fixed DC voltage to variable DC voltage. Self-commutated devices (directly on or off devices via gate) like MOSFET, IGBT, power transistors, GTO and IGCT are used for making choppers because they can be commutated by low power control signal and do not need commutation circuit. The chopper was operated at high …
When the motor rotates, the load of the system may rotate or may go through a translational motion. In the translational motion, the position of the body changes from point to point in space.The speed of the load may be different from that of the motor. If the load has different parts, their speed may …
The braking is the process of reducing the speed of an induction motor. In braking, the motor works as a generator developing a negative torque which opposes the motion of a motor. The braking of an induction motor is mainly classified into three types. They are Regenerative Braking Plugging or reverse voltage braking Dynamic Braking AC …
For variable speed applications, the DC motor drives are used in the past. But this motor has several disadvantages like the presence of commutator and brushes due to which frequent maintenance is required. This problem is overcome by the variable speed induction motor drive. The induction motor drive is cheaper, lighter, smaller, more efficient and …
Definition: The self-controlled variable frequency drive employing a sinusoidal PMAC (Permanent Magnet Alternating Current) motor is called brushless DC motor drive. The brushless DC motor drive has some advantages like practically they require no maintenance and have a long life. They also have low frequency, low inertia and friction, and low radio frequency interference and …
Definition: The static Kramer-drive is the method of controlling the speed of an induction motor by injecting the opposite-phase voltage in the rotor circuit. The injected voltage increases the resistance of the rotor, thus controlled the speed of the motor. By changing the injected voltage, the resistance and speed of an induction motor are controlled. …
The Static Scherbius Drive provides the speed control of a wound rotor motor below synchronous speed. The portion of rotor AC power is converted into DC by a diode bridge. The controlled rectifier works as an inverter and converts the DC power back into AC and feeds it back to the AC source. This drive …
Definition: The voltage source inverter is defined as the inverter which takes a variable frequency from a DC supply. The input voltage of the voltage source inverter remains constant, and their output voltage is independent of the load.The magnitude of the load current depends on the nature of the load impedance. The figure below shows …
Definition: Tractive effort is defined as the force at the rims or the outer edges of the driving wheels of moving trains. In other words, it is the sum of the tractive force and rolling effort on the road surface. In the main line train, tractive effort is caused by the locomotive, and in a suburban …
Definition: The current source inverter converts the input direct current into an alternating current. In current source inverter, the input current remains constant but this input current is adjustable. The current source inverter is also called current fed inverter. The output voltage of the inverter is independent of the load. The magnitude and nature of …
