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Conversely, a current source provides a constant current, as long as the impedance of the load is sufficiently lower than the current source's parallel impedance (which is preferably very high and ideally infinite). In the case of transistor current sources, impedances of a few megohms (at low frequencies) are typical. Because power is current ...
In a line-commutated converter, the DC current (usually) cannot change direction; it flows through a large inductance and can be considered almost constant. On the AC side, the converter behaves approximately as a current source, injecting both grid-frequency and harmonic currents into the AC network.
In a line-commutated converter, the DC current does not change direction; it flows through a large inductance and can be considered almost constant. On the AC side, the converter behaves approximately as a current source, injecting both grid-frequency and harmonic currents into the AC network.
At a short time scale, an inductor can be considered as a current source as it maintains a constant current. This conversion is necessary because if the capacitor were connected directly to the voltage source, the current would be limited only by the parasitic resistance, resulting in high energy loss.
A constant current source circuit constructed with LM317. The device can be configured to regulate the current to a load, rather than the voltage, by replacing the low-side resistor of the divider with the load itself. The output current is that resulting from dropping the reference voltage across the resistor. Ideally, this is:
Fig 4: Waveforms of current and voltage in a buck–boost converter operating in discontinuous mode. In some cases, the amount of energy required by the load is small enough to be transferred in a time smaller than the whole commutation period. In this case, the current through the inductor falls to zero during part of the period.
In electronics, a constant current system is one that varies the voltage across a load to maintain a constant electric current.When a component is indicated to be driven by a constant current, the driver circuit is, in essence, a current regulator and must appear to the component as a current source of suitable reliability.
Charge pumps are used in H bridges in high-side drivers for gate-driving high-side n-channel power MOSFETs and IGBTs. When the centre of a half bridge goes low, the capacitor is charged through a diode, and this charge is used to later drive the gate of the high-side FET a few volts above the source voltage so as to switch it on.