KR101558770B1 - Charging device of vehicle - Google Patents

Abstract

The present invention relates to a charging device for a vehicle. Specifically, the present invention relate to a technique for effectively controlling a converter which charges a battery used for a hybrid electric vehicle or fuel electric vehicle. The charging device for a vehicle includes a boost converter which converts AC power applied to a power node into DC power, and a DC/DC converter which converts DC power applied to the boost converter into a battery charging voltage and supplies the converted voltage to the battery. The DC/DC converter resonates a capacitor which is formed in a snubber circuit and a leakage inductance generated in a primary coil part.

Description

{CHARGING DEVICE OF VEHICLE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device for a vehicle, and more particularly, to a charging device for a hybrid electric vehicle or a fuel cell vehicle.

With the recent development of eco-friendly vehicles such as plug-in hybrid electric vehicles (HEV), electric vehicles (EV), and fuel cell electric vehicles (FCEV) On-Board Charger) is an essential part. Here, the OBC is a charging device for charging a high-voltage battery.

The OBC includes a PFC (Power Factor Correction) boost converter (PFC) that converts AC power to DC power for improving power factor, an isolated DC / DC converter that converts the voltage converted from the PFC to DC power to battery charging voltage Converter.

The DC / DC converter has a function of charging the auxiliary battery and monitoring the electric load of the vehicle by converting the high voltage DC voltage coming from the vehicle's high voltage battery into the low voltage DC voltage.
The contents of such a DC / DC converter are disclosed in Korean Patent Laid-Open Publication No. 2013-0003978 (published January 9, 2013) entitled " Apparatus and Method for Controlling Low-Voltage DC Converter at Startup of Hybrid Vehicle ".

However, the output voltage of the OBC is quite high, which can cause a large voltage spike in the transformer secondary rectifier of the DC / DC converter. This has the disadvantage of requiring the use of expensive devices that can corrupt rectifier elements or cover spike voltages. In addition, a rectifier element having a high internal breakdown voltage is disadvantageous in terms of loss, and the efficiency is also reduced.

In the present invention, a snubber circuit is added to prevent voltage spikes generated in a rectifier of a converter and an on-board charger (OBC) efficiency is improved by resonating a leakage inductance and a capacitor generated on the primary coil side of the transformer And the like.

A charging device for a vehicle according to an embodiment of the present invention includes a boost converter for converting AC power applied to a power supply node to DC power; And a DC / DC converter for converting the DC power supplied from the boost converter to a battery charging voltage and supplying the DC power to the battery, wherein the DC / DC converter is configured to convert the voltage supplied to the primary coil A switching unit for controlling the switching unit; Leakage inductance occurring between the output end of the switching unit and the primary coil side; A transformer to which an AC voltage is applied through a switching operation of the switching unit; A rectifying part including a plurality of diodes for rectifying the AC voltage output from the transformer to a direct current; And a snubber circuit including a capacitor for reducing the peak voltage of the rectifying part. The DC / DC converter resonates the leakage inductance generated on the primary coil side and the capacitance of the capacitor to generate a current flowing on the primary coil side when the switching part is turned off Is reduced.

The present invention provides the following effects.

First, the on-board charger efficiency can be improved by reducing the turn-off loss of the leading switch by resonating the leakage inductance generated at the primary coil side of the transformer and the capacitor of the snubber circuit.

Second, the RMS (Root Mean Square) current of the reading switch is reduced to reduce the conduction loss of the switch and reduce the battery charging time.

It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. .

1 is a configuration diagram of a charging device for a vehicle according to an embodiment of the present invention;
Fig. 2 and Fig. 3 are waveform diagrams for explaining the operation of the charging device for a vehicle. Fig.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of a charging device for a vehicle according to an embodiment of the present invention.

The embodiment of the present invention includes a power supply unit 100, a boost converter 200, a direct current (DC / DC) converter 300, and a high voltage battery 400.

Here, the power supply unit 100 includes a power supply 110 and a plurality of rectification diodes D1 to D4. The power source 110 supplies AC power. The plurality of rectifying diodes D1 to D4 rectify the AC power supplied from the power supply unit 110. [ The plurality of commutation diodes D1 to D4 are connected between the power source node A and the power source node B and are connected in a forward direction from the power source node B to the power source node A. [

The boost converter 200 converts the AC power supplied from the power supply unit 100 to DC power to improve the power factor. The boost converter 200 may correspond to a PFC (Power Factor Correction) boost converter.

In the embodiment of the present invention, the boost converter 200 includes a PFC (Power Factor Correction) boost converter. However, the present invention is not limited thereto, and the converter of the present invention may be composed of various types of converters.

The boost converter 200 includes capacitors C1 and C2, inductors L1 and L2, switching elements S1 and S2, and a plurality of diodes D5 to D8. The capacitors C1 and C2 are connected between the power supply nodes A and B, respectively. The inductors L1 and L2 are connected in parallel to the power supply node A. Diodes D5 and D6 are connected in series with inductors L1 and L2, respectively.

The switching element S1 is connected between the output terminal of the inductor L1 and the power supply node B. The drain terminal of the switching element S1 is connected to the output terminal of the inductor L1 and the source terminal is connected to the node B. The diode D7 is connected in parallel with the switching element S1 to serve as a parasitic diode.

The switching element S2 is connected between the output terminal of the inductor L2 and the power supply node B. The drain terminal of the switching element S2 is connected to the output terminal of the inductor L2, and the source terminal is connected to the node B. The diode D8 is connected in parallel with the switching element S2 to serve as a parasitic diode. Here, the switching elements S1 and S2 may be formed of a metal oxide semiconductor field effect transistor (MOSFET).

The gate terminals of the respective switching elements S1 and S2 are connected to a separate control circuit (not shown). The on-off operation of the switching elements S1 and S2 is controlled in accordance with the control of the control circuit.

The DC / DC converter 300 includes a switching unit 310, a transformer 320, a rectifying unit 330, a snubber circuit 340, and a filter unit 350.

Here, the switching unit 310 includes a plurality of switching elements S3 to S6 and a plurality of diodes D9 to D12. In the embodiment of the present invention, the switching unit 310 includes a plurality of switching elements S3 to S6 and a plurality of diodes D9 to D12. However, the present invention is not limited to this, and the circuit configuration and the connection structure of the switching unit 310 can be sufficiently changed.

The switching elements S3 and S4 are connected in series between the node C and the node D. The switching elements S5 and S6 are connected in series between the node C and the node D. The drain terminal of the switching element S3 is connected to the node C and the source terminal is connected to the node E. [ Then, the drain terminal of the switching element S4 is connected to the node E and the source terminal is connected to the node D.

The drain terminal of the switching element S5 is connected to the node C and the source terminal is connected to the node F. [ Then, the drain terminal of the switching element S6 is connected to the node F and the source terminal is connected to the node D. The plurality of diodes D9 to D12 are connected in parallel with the plurality of switching elements S3 to S6, respectively.

The switching unit 310 adjusts the voltage supplied to the nodes E and F by controlling the duty by shifting the phase of the turn-on signal of the switching elements S3 to S6. That is, the switching unit 310 controls the pulse width of the voltage supplied to the primary coil 321 according to the period during which the switching elements S3 to S6 are simultaneously turned on. The gate terminals of the respective switching elements S3 to S6 are connected to a separate control circuit (not shown). The on-off operation of the switching elements S3 to S6 and the phase of the signal are controlled in accordance with the control of the control circuit.

Leakage inductance L3 is generated between node E and the primary coil side of transformer 320. The leakage inductance L3 is a value of a leakage inductance flowing to the primary coil 321 side of the transformer 320 in accordance with a change in current supplied from the node E.

The transformer 320 includes a primary coil 321, a core 323, and a secondary coil 322. The transformer 320 converts the voltage applied through the nodes E and F and outputs the converted voltage to the rectifier 330.

Here, the primary coil 321 and the secondary coil 322 are formed on both sides with respect to the transformer 323. Then, the primary coil 321 is connected to the node F. Further, the secondary coil 322 is connected to the nodes G, H.

The rectifying unit 330 includes a plurality of rectifying diodes D13 to D16. The plurality of rectifying diodes D13 to D16 rectify the AC power applied from the output nodes G and H of the secondary coil 322 to DC. The plurality of rectifying diodes D13 to D16 are connected in the forward direction from the node J to the node I direction.

The snubber circuit 340 is connected to the output terminal of the rectifier 330 to absorb a surge voltage or a ringing voltage such as a voltage spike generated in the rectifier 330. That is, the snubber circuit 340 reduces the reverse voltage generated in the rectifying diodes D13 to D16 of the rectifying unit 330. [ This snubber circuit 340 includes a capacitor C3 and diodes D17 and D18.

Here, the capacitor C3 is connected between the node I and the node K. [ Then, the diode D17 is connected in a forward direction between the node J and the node K. The diode D18 is connected in parallel with the diode D18. That is, the node K and the node L are connected in the forward direction.

The peak current flowing through the primary coil 321 of the transformer 320 can be increased due to the current flowing through the capacitor C3 of the snubber circuit 340. [ In this case, the turn-off loss increases when the leading switches (switching elements S3 and S4) are turned off. Accordingly, the embodiment of the present invention resonates the leakage inductance L3 and the capacitor C3 of the snubber circuit 340 to reduce the turn-off loss of the switching unit 310. [ That is, in the snubber circuit 340, the capacitance of the capacitor C3 is reduced to resonate with the leakage inductance L3.

When the capacitance of the capacitor C3 is reduced to resonate with the leakage inductance L3, the current of the primary coil 321 increases and then decreases again. Then, when the leading switches (switching elements S3 and S4) are turned off, the current decreases, thereby reducing the turn-off loss.

The filter unit 350 includes an inductor L4 and a capacitor C4 to smooth the output voltage of the rectifying unit 330. [ Inductor L4 is a smoothing inductor that converts the alternating current of node I into a direct current. The inductor L4 is connected between the node I and the node L. [ Then, the capacitor C4 is connected between the node L and the node J. This capacitor C4 is a smoothing capacitor that keeps the voltage applied to the node L constant. The voltage output from the inductor L4 and the capacitor C4 is supplied to the high-voltage battery 400. [

2 is an operational waveform diagram of a charging device for a vehicle.

It can be seen that the reverse voltage of the rectifier diodes D13 to D16 is reduced as in (1) when the snubber circuit 340 absorbs the peak voltage of the rectification part 330. [

However, the peak current flowing through the primary coil 321 of the transformer 320 can be as high as (2) due to the current flowing in the capacitor C3 of the snubber circuit 340. [ In this case, the turn-off loss increases when the leading switches (switching elements S3 and S4) are turned off. In addition, the RMS (Root Mean Square) current of the reading switch is increased to increase the conduction loss, and the on-board charger (OBC) efficiency may be reduced.

(3) represents the voltage waveform that flows in the capacitor C3 of the snubber circuit 340. [ (3), it can be seen that the voltage of the capacitor C3 of the snubber circuit 340 always flows above OV.

2 is an operational waveform diagram relating to a lagging switch (switching elements S5 and S6) of the switching unit 310. Reference numeral 5 denotes an operating waveform of a leading switch of the switching unit 310 S3, and S4 shown in FIG.

3 is an operational waveform diagram of a charging device for a vehicle according to an embodiment of the present invention.

When the snubber circuit 340 absorbs the peak voltage of the rectification part 330, the reverse voltage of the rectifier diodes D13 to D16 appears as a waveform like (6).

The embodiment of the present invention resonates the leakage inductance L3 and the capacitor C3 of the snubber circuit 340 in order to reduce the turn-off loss of the switching unit 310. [ That is, in the snubber circuit 340, the capacitance of the capacitor C3 is reduced to resonate with the leakage inductance L3.

When the capacitance of the capacitor C3 is reduced to resonate with the leakage inductance L3, the current of the primary coil 321 increases and then decreases to appear as a sine wave of (7). Then, when the leading switches (switching elements S3 and S4) are turned off, the current decreases, thereby reducing the turn-off loss.

(8) represents the voltage waveform flowing in the capacitor C3 of the snubber circuit 340. [ (8), it can be seen that there is a period in which the voltage of the capacitor C3 of the snubber circuit 340 becomes OV.

3 is an operation waveform diagram of a lagging switch (switching elements S5 and S6) of the switching unit 310. Reference numeral 10 is a reading switch of the switching unit 310, S3, and S4 shown in FIG.

Claims (7)

A boost converter for converting AC power applied to the power supply node to DC power; And
And a DC / DC converter for converting the DC power supplied from the boost converter to a battery charging voltage and supplying the DC power to the battery,
The DC / DC converter
A switching unit for controlling a voltage supplied to the primary coil in accordance with the turn-on or turn-off of the plurality of switching elements;
A leakage inductance occurring between an output end of the switching unit and the primary coil side;
A transformer to which an AC voltage is applied through a switching operation of the switching unit;
A rectifier including a plurality of diodes for rectifying the AC voltage output from the transformer to a direct current; And
And a snubber circuit including a capacitor for reducing a peak voltage of the rectifying part,
The DC / DC converter
Wherein the leakage inductance generated on the primary coil side and the capacitance of the capacitor are resonated to reduce the current flowing on the primary coil side when the switching unit is turned off. The power converter according to claim 1, wherein the boost converter
A first capacitor coupled between the first power supply node and the second power supply node;
A first inductor formed on the first power supply node;
A first diode connected to an output terminal of the first inductor;
A second capacitor coupled between the output of the first diode and the second power node;
A first switching device connected between the first power supply node and the second power supply node and performing a switching operation; And
And a third diode connected in parallel with the first switching device. 3. The power converter according to claim 2, wherein the boost converter
A second inductor connected in parallel with the first inductor;
A second diode connected to an output terminal of the second inductor;
A second switching element connected between the second inductor and the second power supply node for switching operation; And
And a fourth diode connected in parallel with the second switching device. delete 2. The method of claim 1, wherein the snubber circuit
A third capacitor coupled to a first output node of the rectifier;
A fifth diode connected between the second output node of the rectification section and the third capacitor; And
And a sixth diode connected in parallel with the fifth diode. delete The charging device for a vehicle according to claim 1, wherein the boost converter and the DC / DC converter are applied to an on-board charger (OBC).

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