| 摘要 |
A technique performed by a transformer-coupled DC-DC converter is described for recovering energy, due to leakage inductance in the transformer. A main power supply, providing a power supply voltage to a Vin terminal, is intermittently coupled to the primary winding of the transformer by a switching transistor. When the switching transistor is turned off, creating a voltage spike in the primary winding due to leakage inductance, the spike is conducted by a forward biased diode and filtered by a capacitor. The voltage at the capacitor (Vc) is then applied as an input voltage to a small pulse width modulated (PWM) regulator. The output of the PWM regulator is coupled to the Vin terminal along with the main power supply. The PWM regulator regulates the input voltage Vc to be a predetermined amount above the power supply voltage. Since the voltage spike energy is used to create the input voltage for the PWM regulator, and the output of the PWM regulator is fed back into the Vin terminal, the energy is recovered. Also, since Vc can be set to be any voltage above Vin, the voltage across the switching transistor is greatly limited.
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