| 摘要 |
A switching mode regulator of improved efficiency and reliability is described in which both the turn-on and turn-off transients are controlled. In switching mode regulators, a flyback diode turns off when the transistor switch turns on, but if stored charge keeps the diode on after the transistor switch has come on, very large currents which stress the transistor and represent loss, may result. When the transistor switch turns off, the energy storing inductance required in such supplies to maintain current to the load, causes the voltage across the switch to increase more rapidly than the current is extinguished, thus tending to exceed the ratings of the transistor switch for reverse secondary breakdown. Improved transient performance is achieved by the provision of a novel current transformer which aids in storing energy from the turn-on transient, and which next couples a portion of the stored energy to a capacitor from which the energy is returned to the load in a manner which reduces the rate of change of voltage (dv/dt) applied to the switch at turn-off and precludes reverse secondary breakdown. The whole process is energy conservative. In addition, since switching transistors of lower ratings may be employed, improved performance, reliability, and economy are achieved.
|
