Power converter

Patent metadata

Field	Value
Publication number	US-10211719-B2
Application number	US-201515551635-A
Country	US
Kind code	B2
Filing date	Mar 3, 2015
Priority date	Mar 3, 2015
Publication date	Feb 19, 2019
Grant date	Feb 19, 2019

Abstract

An electric power converter is provided, at low costs and in high efficiency, which also enables voltage conversion to be capable of dealing with sharp load variation, even when input voltage and output current ranges are wide. The converter includes a non-isolated buck-boost converter circuit for outputting a DC voltage by increasing or decreasing a voltage being inputted into the circuit, an isolated converter circuit for outputting a DC voltage to a load by inputting a DC voltage outputted from the non-isolated buck-boost converter circuit, and a control unit for controlling the non-isolated buck-boost converter circuit and the isolated converter circuit, whereby the control unit adjusts using only the non-isolated buck-boost converter circuit, by performing the control of a buck-boost voltage ratio between the voltage inputted thereinto and an output voltage of the isolated converter circuit, so as to make the output voltage coincident with its target value.

First claim

What is claimed is:

1. An electric power converter, comprising:
a non-isolated buck-boost converter circuit for outputting, by increasing or decreasing a voltage being inputted thereinto, a DC voltage;
an isolated converter circuit for outputting a DC voltage to a load by inputting a DC voltage outputted from the non-isolated buck-boost converter circuit, wherein the isolated converter circuit includes a transformer having a primary winding and a secondary winding, and wherein a resonance type converter is configured to connect a third semiconductor switching device, a fourth semiconductor switching device and a resonance capacitor to the primary winding of the transformer; and
a control device for controlling the non-isolated buck-boost converter circuit and the isolated converter circuit, wherein the control unit is configured to control a switching frequency of a waveform applied to the third semiconductor switching device based on a value of the resonance capacitor.

2. The electric power converter as set forth in claim 1 , wherein the control device performs a control of a buck-boost voltage ratio, by only the non-isolated buck-boost converter circuit, between a voltage being inputted thereinto and an output voltage of the isolated converter circuit.

3. The electric power converter as set forth in claim 1 , wherein the non-isolated buck-boost converter circuit includes an H-bridge type buck-boost chopper having a first smoothing reactor, a first smoothing capacitor, two diodes, a first semiconductor switching device for controlling an application time of an input voltage into the first smoothing reactor, and a second semiconductor switching device for controlling a DC voltage stored in the first smoothing capacitor.

4. The electric power converter as set forth in claim 3 , wherein the control device turns off the second semiconductor switching device at all times and controls a buck voltage ratio by means of the first semiconductor switching device when the non-isolated buckboost converter circuit is controlled to perform a buck operation on an input voltage thereinto, and turns on the first semiconductor switching device at all times and controls a boost voltage ratio by means of the second semiconductor switching device when the non-isolated buck-boost converter circuit is controlled to perform a boost operation on an input voltage thereinto.

5. The electric power converter as set forth in claim 3 , wherein the control device turns on the first semiconductor switching device at all times and turns off the second semiconductor switching device at all times, when a buck-boost voltage ratio of the non-isolated buck-boost converter circuit is one.

6. The electric power converter as set forth in claim 1 , wherein
the isolated converter circuit includes
a rectifier circuit and a second smoothing capacitor connected to the secondary winding of the transformer.

7. The electric power converter as set forth in claim 6 , wherein a rectifier circuit of the isolated converter circuit is constituted of diodes.

8. The electric power converter as set forth in claim 6 , wherein a rectifier circuit of the isolated converter circuit is a synchronous rectifier circuit constituted of semiconductor switching devices.

9. The electric power converter as set forth in claim 8 , wherein the control unit increases an output voltage of the non-isolated buck-boost converter circuit, when an output voltage of the isolated converter circuit increases.

10. The electric power converter as set forth in claim 8 , wherein the control unit halts the synchronous rectifier circuit of the isolated converter circuit, when an output voltage of the isolated converter circuit increases.

11. The electric power converter as set forth in claim 8 , wherein the isolated converter circuit includes an output-current detection circuit for detecting an electric current flowing through the synchronous rectifier circuit, and the control unit turns off the synchronous rectifier circuit when an electric current detected by the output-current detection circuit reaches less than or equal to a threshold value.

12. The electric power converter as set forth in claim 6 , wherein the resonance reactor of the isolated converter circuit is made of a leakage inductance of the transformer having a primary winding and a secondary winding.

13. The electric power converter as set forth in claim 6 , wherein the isolated converter circuit comprises an LLC converter.

14. The electric power converter as set forth in claim 13 , wherein the switching frequency is a fixed switching frequency.

15. The electric power converter as set forth in claim 14 , wherein the control unit controls to make a time of half a period of the fixed switching frequency equal to a time in which a dead time is added to half a period of a series resonance frequency determined between the resonance capacitor and the resonance reactor.

16. The electric power converter as set forth in claim 14 , further comprising
a temperature sensor, wherein
the control unit controls a switching frequency of the LLC converter in accordance with a temperature value detected by the temperature sensor.

17. The electric power converter as set forth in claim 14 , wherein the isolated converter circuit includes an output-current detection circuit for detecting an electric current flowing through an output circuit, and the control unit controls a switching frequency of the LLC converter in accordance with an electric current value detected by the output-current detection circuit.

18. The electric power converter as set forth in claim 1 , further comprising
an electric current sensor, wherein
the control unit lowers a target value of an output voltage of the electric power converter in accordance with an electric current value detected by the electric current sensor.

19. The electric power converter as set forth in claim 18 , wherein a semiconductor switching device of the electric power converter is a device made of a wide band-gap semiconductor.

20. The electric power converter as set forth in claim 19 , wherein the wide band-gap semiconductor is a semiconductor using silicon carbide, a gallium nitride-based material, or diamond.

21. An electric power converter, comprising:
a non-isolated buck-boost converter circuit for outputting, by increasing or decreasing a voltage being inputted thereinto, a DC voltage, wherein the non-isolated buck-boost converter circuit includes a polarity reversal type buck-boost chopper having a first smoothing reactor, a first smoothing capacitor, a diode, and a first semiconductor switching device configured such that a second polarity on the first smoothing capacitor appears reversed with respect to a first voltage polarity on the input of the non-isolated buck-boost converter circuit;
an isolated converter circuit for outputting a DC voltage to a load by inputting a DC voltage outputted from the non-isolated buck-boost converter circuit; and
a control device for controlling the non-isolated buck-boost converter circuit and the isolated converter circuit.

22. The electric power converter as set forth in claim 21 , wherein the control device turns off the first semiconductor switching device when the electric power converter does not transmit electric power to a load.

23. The electric power converter as set forth in claim 21 , wherein
the isolated converter circuit includes a transformer having a primary winding and a secondary winding; and

Assignees

• Mitsubishi Electric Corp

Inventors

• Tanaka Yuya

Classifications

• H02M3/3374 Primary

  with preregulator, e.g. current injected push-pull · CPC title

• H02M3/28

  using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC · CPC title

• H02M3/155

  using semiconductor devices only · CPC title

• H02M1/083 Primary

  for the ignition at the zero crossing of the voltage or the current · CPC title

• H02M3/33523

  with galvanic isolation between input and output of both the power stage and the feedback loop · CPC title