Patent ID: 11901826
Assignee: DELTA ELECTRONICS, INC.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  G  Y | IPC G  H

Claim 9:
10. A power converter having first and second input terminals to receive an input signal from a voltage source to provide an output voltage or an output current to at least one load, comprising:
(a) a transformer having primary and secondary windings;
(b) a primary-side circuit, comprising:
(i) first, second, third, and fourth series-connected switching devices connected across the first and second input terminals, the first and second switching devices being controlled by first and second switch control signals, respectively, and the third and the fourth switching devices being controlled by a third and a fourth complementary switch control signals, respectively; and
(ii) a resonant tank circuit, the resonant tank circuit being coupled (1) between a first electrical node, being a common electrical node between the first and second switching devices, and a second electrical node, being a common electrical node between the third and fourth switching devices; and (2) to the primary winding of the transformer;

(c) a secondary-side circuit coupled to the secondary winding of the transformer, the secondary-side circuit comprising a filter capacitor providing the output voltage or output current to the at least one load; and the first, second, third, and fourth switch control signals are periodic with a common switching period, (iii) within the common switching period, (1) each switch control signal of the first to fourth switch control signals has two rising edges and two falling edges; and either (2) the first rising edge of the first switch control signal lags the first rising edge of the fourth switch control signal by a first predetermined time, while the second rising edge of the first switch control signal leads the second rising edge for the fourth switch control signal by a second predetermined time, or (3) the first rising edge of the first switch control signal leads the first rising edge of the fourth switch control signal by a first predetermined time, while the second rising edge of the first switch control signal lags the second rising edge for the fourth switch control signal by a second predetermined time, and (iv) a control circuit, the control circuit varies the common switching period, the first predetermined time, and the second predetermined time,
wherein the control circuit operates the first to fourth switching devices based on the output voltage or the output current, the control circuit being configured to operate in a first modulation mode and a second modulation mode, wherein under the first modulation mode, the first to fourth switching devices are operated to generate the output voltage comprising three different voltage levels, and wherein under the second modulation mode, the first to fourth switching devices are operated to generate the output voltage comprising two different voltage levels, wherein the control circuit is further configured to operate in a third modulation mode, under the third modulation mode, the first to fourth switching devices are operated to generate a zero voltage level,
wherein the control circuit operates in the third modulation mode between operating in the first modulation mode and operating in the second modulation mode, and
wherein the control circuit is further configured to operate in a fourth modulation mode, under the fourth modulation mode, the duty ratio of one of every two pulses of one of the first and second switching devices is increased and the duty ratio of one of every two pulses of one of the third and fourth switching devices is increased, or the duty ratio of one of every two pulses of one of the first and second switching devices is decreased and the duty ratio of one of every two pulses of one of the third and fourth switching devices is decreased.