Hybrid transformer apparatus

Abstract

A hybrid transformer includes a distribution transformer, a compensation transformer, a parallel converter, and a series converter. The compensation transformer is connected in series between the secondary side of the distribution transformer and the load. The parallel converter includes a first full-bridge switching circuit and a first AC-side switch. The input terminal of the first full-bridge switching circuit is coupled to the secondary side of the distribution transformer, and the first AC-side switch is connected across the input terminal of the first full-bridge switching circuit. The series converter includes a second full-bridge switching circuit and a second AC-side switch. The input terminal of the second full-bridge switching circuit is coupled to the output terminal of the first full-bridge switching circuit, the output terminal of the second full-bridge switching circuit is coupled to the compensation transformer, and the second AC-side switch is connected across the output terminal of the second full-bridge switching circuit.

Claims

1. A hybrid transformer configured to couple to a load, the hybrid transformer comprising: a distribution transformer including a primary side and a secondary side, the secondary side configured to generate an initial signal and coupled to the load; a compensation transformer connected in series between the secondary side and the load; a parallel converter including a first full-bridge switching circuit and a pair of first AC-side switches, one pair of input terminals of the first full-bridge switching circuit coupled to the secondary side of the distribution transformer, the pair of first AC-side switches connected in series and bridging the pair of input terminals of the first full-bridge switching circuit; and a series converter including a second full-bridge switching circuit and a pair of second AC-side switches, one pair of input terminals of the second full-bridge switching circuit coupled to one pair of output terminals of the first full-bridge switching circuit, one pair of output terminals of the second full-bridge switching circuit coupled to the compensation transformer, the pair of second AC-side switches connected in series and bridging the pair of output terminals of the second full-bridge switching circuit.

2. The hybrid transformer as described in claim 1 further includes a controller, wherein the second full-bridge switching circuit includes a first switching switch, a second switching switch, a third switching switch and a fourth switching switch, the first switching switch and the second switching switch being connected in series to form a left arm, and the third switching switch and the fourth switching switch being connected in series to form a right arm, the controller being configured to control the first switching switch and the fourth switching switch according to a pulse width modulation signal during one half-cycle of the original signal, and to control one of the pairs of second AC side switches according to an inverted signal of the pulse width modulation signal.

3. The hybrid transformer as described in claim 2, wherein, The controller is further configured to control the other of the pair of second AC side switches according to a high-level DC signal during that half-cycle.

4. The hybrid transformer as described in claim 2, wherein, The controller is further configured to control the second and third switching switches according to the pulse width modulation signal during the other half cycle of the original signal, and to control the other of the second AC side switches according to the inverted signal of the pulse width modulation signal.

5. The hybrid transformer as described in claim 2, wherein, The controller includes a pair of inverters, a first terminal and a second terminal, the first terminal being coupled to the first switch and the fourth switch, and coupled to one of the second AC side switches through one of the inverters, the second terminal being coupled to the second switch and the third switch, and coupled to the other of the second AC side switches through the other of the inverters.

6. The hybrid transformer as described in claim 2, wherein, The controller further includes a first pulse width modulator, which is coupled to the pair of outputs of the second full-bridge switching circuit to receive a compensation signal. The controller is configured to generate a modulation signal in phase according to the voltage of the compensation signal, and the first pulse width modulator modulates the modulation signal to generate the pulse width modulation signal.

7. The hybrid transformer as described in claim 6, wherein, The controller is further configured to receive a reference signal from a management system. The compensation transformer compensates the original signal according to the compensation signal to generate an output signal. The controller is coupled to the secondary side to receive the output signal and generates a feedback signal according to the difference between the reference signal and the output signal. The first pulse width modulator further adjusts the pulse width modulation signal according to the feedback signal.

8. The hybrid transformer as described in claim 1 further includes a controller, wherein the first full-bridge switching circuit includes a fifth switching switch, a sixth switching switch, a seventh switching switch and an eighth switching switch, the fifth switching switch and the sixth switching switch being connected in series to form a left arm, and the seventh switching switch and the eighth switching switch being connected in series to form a right arm, the controller being configured to control the fifth switching switch and the eighth switching switch according to a pulse width modulation signal during half a cycle of the original signal, and to control one of the first AC side switches according to an inverted signal of the pulse width modulation signal.

9. The hybrid transformer as described in claim 8, wherein, The controller further includes a second pulse width modulator, which is coupled to the pair of outputs of the first full-bridge switching circuit to receive a DC signal. The second pulse width modulator adjusts the pulse width modulation signal according to the DC signal.

10. The hybrid transformer as described in claim 9, wherein, The controller reduces the duty cycle of the pulse width modulation signal in response to the DC signal being greater than a preset voltage range; and increases the duty cycle of the pulse width modulation signal in response to the DC signal being less than the preset voltage range.

Images