Patent ID: 9167661
Filing Date: 2015-10-20
Classification: G05F,H02M,H05B,Y02B

Abstract:
1. A power supply device, comprising: a DC power supply section that outputs a DC voltage; a voltage conversion section that is provided with a switching element, an inductor and a capacitor, and supplies a DC power to a load by ON/OFF drive of the switching element, using the DC power supply section as an input power source; a current detection section that detects a current flowing through the load; a control section that performs the ON/OFF drive of the switching element based on a detection result obtained in the current detection section so that a DC electricity supplied from the voltage conversion section to the load is maintained constant; and an energy detection section that detects energy which is released by the inductor, wherein the control section comprises a calculation section that calculates a drive period of the switching element according to increase or decrease of the DC power supplied to the load, and a period comparator that compares a calculation result obtained in the calculation section with an upper limit value of the drive period of the switching element, wherein when the drive period of the switching element calculated by the calculation section is shorter than the upper limit value, the control section is configured to set the drive period of the switching element, using the calculation result obtained in the calculation section, and to turn on the switching element with a timing of when the energy released by the inductor is reduced to zero, and wherein when the drive period of the switching element calculated by the calculation section is longer than the upper limit value, the control section is configured to set the drive period of the switching element, using the upper limit value.