Patent ID: 11888406
Assignee: APPLE INC.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  Y | IPC H

Claim 0:
1. An AC-AC converter comprising:
a stack of four switching devices, wherein an input of the AC-AC converter is coupled across the stack of four switching devices and an output of the AC-AC converter is taken from first terminal coupled to a connection point of first and second switching devices of the stack and a second terminal coupled to a connection point of third and fourth switching devices of the stack; and
a controller that operates the switching devices such that:
during a positive half cycle of an AC input voltage, first and second switching devices of the stack are operated with an alternating 50% duty cycle and third and fourth switching devices of the stack are constantly on; and
during the negative half cycle of the AC input voltage, the third and fourth switching devices of the stack are operated with an alternating 50% duty cycle and the first and second switching devices of the stack are constantly on;

wherein:
during the positive half cycle, the duration of the on-times of the first and second switching devices determine the magnitude of the AC voltage between the first and second terminals; and
during the negative half cycle, the duration of the on times of the third and fourth switching devices determine the magnitude of the AC voltage between the first and second terminals.