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beyondlight
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Homework Statement
We have a small car that is powered by a battery that feeds a DC-motor. The system consists of two DC-to-DC converters that controls the rotor and stator current. The DC-motor i separately magnetized.
The purpoce of the DC-to-DC converters is to modulate the time the transistors are on and off so that the voltage over the motor can be regulated.
When transistors T1 and T4 are on T2 and T3 are off.
http://oi46.tinypic.com/10xhkpd.jpg
Homework Equations
[tex]U_1=\frac{t_{p}}{T}U_2[/tex]
The Attempt at a Solution
I can't decide between two alternatives.
The first is that the current through the DC motor has the same direction (rotor-curent I_a) Which means that during the time t-->T the current I_a must go in the negative direction, over the capacitor instead of the battery.
In this case if it is right, how does the voltage vary over the motor when transistors T2 and T3 are on?
http://oi48.tinypic.com/rib3hi.jpg
The second is that the current I_a has different directions according tho which transistors are open. If the second alternative is correct, does it mean that the motor works in both directions and thus the wheels can't roll or does the commutator make the current go in the right direction so that the weels can spinn in the right direction?
http://oi50.tinypic.com/2eyl8gn.jpgWhen i know how the currents and voltages actually do vary in the circuit, then i need to calculate how the average value of
u_x1 and u_x2
vary depending on the pulseratio t/T. And how U_a (DC-voltage) vary as a function of the pulseratio.
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