Ac-ac converter

Patent metadata

Field	Value
Publication number	US-2026039215-A1
Application number	US-202519288329-A
Country	US
Kind code	A1
Filing date	Aug 1, 2025
Priority date	Aug 1, 2024
Publication date	Feb 5, 2026
Grant date	—

Abstract

An AC-AC converter is provided. The AC-AC converter includes a primary circuit, a secondary circuit, a transformer, a resonant tank, and a controller. The primary circuit includes four bidirectional switches, each including upper and lower switches connected back-to-back and capable of operating in four quadrants in a voltage-current plane. The first and fourth bidirectional switches operate synchronously, and the second and third bidirectional switches operate synchronously. When the input voltage is greater than a predefined threshold voltage, the first and second lower switches are maintained in an on state, and the first and second upper switches operate with PWM signals and are complementary to each other. When the input voltage is smaller than an additive inverse of the predefined threshold voltage, the first and second upper switches are maintained in the on state, and the first and second lower switches operate with PWM signals and are complementary to each other.

First claim

What is claimed is:

1 . An AC-AC converter, comprising:
a primary circuit, configured to receive an input voltage, which is AC, and comprising:
a first bidirectional switch and a second bidirectional switch, electrically connected in series to form a first bridge arm, wherein the first bidirectional switch comprises a first upper switch and a first lower switch connected back-to-back, and the second bidirectional switch comprises a second upper switch and a second lower switch connected back-to-back; and
a third bidirectional switch and a fourth bidirectional switch, electrically connected in series to form a second bridge arm, which is electrically connected in parallel to the first bridge arm, wherein the third bidirectional switch comprises a third upper switch and a third lower switch connected back-to-back, and the fourth bidirectional switch comprises a fourth upper switch and a fourth lower switch connected back-to-back; wherein the first to fourth bidirectional switches are capable of operating in four quadrants in a voltage-current plane;
a secondary circuit, configured to provide an output voltage, which is AC, and comprising bidirectional switches capable of operating in the four quadrants in the voltage-current plane; a transformer, comprising a primary winding and a secondary winding electrically connected to the primary circuit and the secondary circuit respectively; a resonant tank, coupled between the primary circuit and the secondary circuit, and comprising a first resonant inductor and a first resonant capacitor, wherein the first resonant inductor, the primary winding, and the first resonant capacitor are electrically connected in series between a connection node of the first and second bidirectional switches and a connection node of the third and fourth bidirectional switches; and a controller, configured to provide control signals for the first bidirectional switch, the second bidirectional switch, the third bidirectional switch, and the fourth bidirectional switch of the primary circuit and the bidirectional switches of the secondary circuit, wherein a control signal of the first upper switch and a control signal of the fourth upper switch are the same, a control signal of the first lower switch and a control signal of the fourth lower switch are the same, a control signal of the second upper switch and a control signal of the third upper switch are the same, and a control signal of the second lower switch and a control signal of the third lower switch are the same, wherein when the input voltage is greater than a predefined threshold voltage, the controller is configured to control the first lower switch and the second lower switch to maintain in an on state, and to control the control signal of the first upper switch and the control signal of the second upper switch to be PWM signals and complementary to each other, wherein when the input voltage is smaller than an additive inverse of the predefined threshold voltage, the controller is configured to control the first upper switch and the second upper switch to maintain in the on state, and to control the control signal of the first lower switch and the control signal of the second lower switch to be PWM signals and complementary to each other.

2 . The AC-AC converter according to claim 1 , wherein when a primary current provided by the primary circuit is greater than a predefined threshold current, the controller is configured to sequentially turn off the first lower switch, turn on the second lower switch, turn off the first upper switch, and turn on the second upper switch; and when the primary current is smaller than an additive inverse of the predefined threshold current, the controller is configured to sequentially turn off the first upper switch, turn on the second upper switch, turn off the second lower switch, and turn on the first lower switch.

3 . The AC-AC converter according to claim 2 , wherein when the input voltage is between the predefined threshold voltage and the additive inverse of the predefined threshold voltage and the primary current is between the predefined threshold current and the additive inverse of the predefined threshold current, the controller is configured to turn on all the switches of the primary circuit, to turn off all the switches of the primary circuit, or to keep previous states of all the switches of the primary circuit.

4 . The AC-AC converter according to claim 1 , further comprising an input capacitor electrically connected in parallel to the primary circuit, wherein the controller is configured to adjust a switching frequency or a duty cycle of the primary circuit according to a difference between a voltage of the input capacitor and a reference voltage.

5 . The AC-AC converter according to claim 1 , wherein the primary circuit, the resonant tank, the transformer, and the secondary circuit form a conversion module, the AC-AC converter comprises a plurality of conversion modules, inputs of the plurality of conversion module are electrically connected in series or parallel, and outputs of the plurality of conversion modules are electrically connected in series or parallel.

6 . The AC-AC converter according to claim 1 , wherein the resonant tank further comprises a second resonant inductor and a second resonant capacitor electrically connected between the secondary winding of the transformer and the secondary circuit.

7 . The AC-AC converter according to claim 1 , wherein the bidirectional switches of the secondary circuit comprise a fifth bidirectional switch, a sixth bidirectional switch, a seventh bidirectional switch and an eighth bidirectional switch, each comprising an upper switch and a lower switch connected back-to-back, the fifth bidirectional switch and the sixth bidirectional switch, electrically connected in series to form a third bridge arm, the seventh bidirectional switch and the eighth bidirectional switch, electrically connected in series to form a fourth bridge arm, the third bridge arm is electrically connected in parallel to the fourth bridge arm.

8 . An AC-AC converter, comprising:
a primary circuit, configured to receive an input voltage, which is AC, and comprising a first bidirectional switch, a second bidirectional switch, a third bidirectional switch, and a fourth bidirectional switch, each capable of operating in four quadrants in a voltage-current plane, wherein the first bidirectional switch and the second bidirectional switch are electrically connected in series to form a first bridge arm, and the third bidirectional switch and the fourth bidirectional switch are electrically connected in series to form a second bridge arm, and the second bridge arm is electrically connected in series to the first bridge arm; a secondary circuit, configured to provide an output voltage, which is AC, and comprising bidirectional switches capable of operating in the four quadrants in the voltage-current plane; a transformer, comprising a primary winding and a secondary winding electrically connected to the primary circuit and the secondary circuit respectively; a resonant tank, coupled between the primary circuit and the secondary circuit, and comprising a first resonant inductor and a first resonant capacitor, wherein the first resonant inductor, the primary winding and the first resonant capacitor are electrically connected in series between a connection node of the first and second bidirectional switches and a connection node of the third and fourth bidirectional switches; and a controller, configured to provide control signals for the first bidirectional switch, the second bidirectional switch, the third bidirectional switch, and the fourth bidirectional switch of the primary circuit and the bidirectional switches of

Assignees

• Delta Electronics Inc

Inventors

• Zhang Chi
• Wang Ruxi
• Barbosa Peter Mantovanelli

Classifications

• H02M1/0077

  Plural converter units whose outputs are connected in series · CPC title

• H02M1/0074

  Plural converter units whose inputs are connected in series · CPC title

• H02M1/0058

  by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero (using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826) · CPC title

• H02M1/0009

  Devices or circuits for detecting current in a converter · CPC title

• H02M5/2932 Primary

  with automatic control of output voltage, current or power · CPC title