Difference between the chopper fed and converter fed drives
Difference between chopper fed and converter fed drives
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The DC machine is powered by the AI converter (Fig.2.6). The converter can be line-switched AC / DC converter or DC / DC chopper. In both cases, the average value uk of the pulsating voltage or terminal of the converter (and therefore the speed w = wk of the drive) can be continuously monitored.
CHOPPER-FED D.C. MOTOR CONDUCTORS
If the source of supply is d.c. (For example in a battery vehicle or a rapid transit system) a cut-type converter is usually used. The battery voltage on and off for varying intervals. The main difference between the thyristor controlled rectifier and the switch is that in the first the motor current always flows through the supply, while in the latter, the motor current flows only from the supply terminals for a part of each cycle.
A single-switch switch using a transistor, MOSFET or IGBT can only supply positive voltage and current to a direct current. Motor, and therefore is restricted to the operation of the motor of the quadrant 1. When speed reversal and / or fast speed is required, more complex circuits, involving two or more power switches, are required, and consequently leads to an increase Of cost.
Many different circuits are used and it is not possible to go into detail here, although it should be mentioned that the chopper circuit described in Chapter 2 only provides an output voltage in the interval 0 <E, where E is the battery voltage, per What this type of switch is only suitable if the motor voltage is less than the voltage of the battery. When the motor voltage is greater than the battery voltage, a 'scheduler' chopper is used using an additional inductance as an intermediate energy accumulator.