Voltage resonant inverter, control method, and surface treatment device

摘要

Excitation current is applied to an excitation winding of a step-up transformer by switching an input voltage with a first switching element. Excitation energy stored causes a voltage resonant state in the secondary side of the step-up transformer during a period when the excitation current is shut off. When the excitation current is shut off, a second resonant circuit provided in the primary side of the step-up transformer enters a resonant state. When a second switching element of the second resonant circuit is turned on, energy returning to an input side in a region where the output voltage is negative is commutated through a second diode to be absorbed in the input voltage. The second switching element is kept off while the second resonant circuit is in the resonant state, turned on when the resonant state ends, and turned off after the first switching element is turned on.

主权项

1. A voltage resonant inverter comprising:
a step-up transformer having an excitation winding and an output winding; and a first switching element that switches an input voltage and intermittently applying an excitation current to the excitation winding, wherein excitation energy stored in the step-up transformer during a period when the excitation current is applied causes a voltage resonant state in a secondary side of the step-up transformer during a period when the excitation current is shut off and generates an alternating output voltage on the output winding, and the voltage resonant inverter further comprises:
a resonant circuit that is provided in a primary side of the step-up transformer and enters a resonant state by a voltage generated at a connection point between the excitation winding and the first switching element when the excitation current is shut off, and includes a second switching element;a first diode that is provided between a frame ground and the resonant circuit, and commutates a current resulting from energy returning to an input side in a region where the alternating output voltage is negative after the second switching element is turned on so that the current is absorbed in the input voltage; anda switching element control circuit that keeps the second switching element off while the resonant circuit is in a resonant state, turns on the second switching element when the resonant state ends, and turns off the second switching element during a period after the first switching element is turned on until the first switching element is turned off.