KR101295317B1 - United charging system for power converting unit of electric vehicle - Google Patents

Abstract

PURPOSE: A complex type charging system for a power converting apparatus of an electric vehicle (xEV) is provided to reduce component cost, by integrating expensive components into a circuit. CONSTITUTION: An external input rectifier part rectifies an external alternate current (AC) input and then outputs the rectified external AC input through an output terminal. A high speed switching part switches a direct current (DC) voltage in a high speed. A transformer part (300) outputs a high frequency AC voltage through a low voltage output terminal. A high voltage smoothing part (400) smooths an AC outputted from the high voltage output terminal into a DC. A low voltage smoothing part (500) smooths an AC outputted from the low voltage output terminal into a DC.

Description

United charging system for power converting unit of electric vehicle

Disclosed are charging circuits, in particular charging systems for use in high voltage battery charging and low voltage batteries of electric vehicles.

BACKGROUND OF THE INVENTION [0002] A continuous charging system for an electric vehicle such as a hybrid electric vehicle (PHEV) or a general electric vehicle (BEV) is a system for charging a high voltage battery for driving an electric vehicle by receiving commercial AC power. : On Board Charger). The fast charging system converts commercial power to direct current through full-wave rectification, then converts the power factor into an active filter, converts it to high-frequency AC with an inverter, converts it into a direct current through a transformer, and supplies high- . The inverter of the on-board type charger includes a high-speed switching circuit that switches an input DC voltage at a high speed and converts the DC voltage into a high-frequency AC current. On the other hand, in an electric vehicle, charging of a low-voltage battery that supplies power to the electric power system for electric power is performed by reducing the output of the high-voltage battery for driving through a DC-DC converter circuit. The high-efficiency DC-DC converter circuit also includes a high-speed switching circuit that switches the input DC voltage at high speed and converts it to a high frequency AC current.

Therefore, electric vehicles are equipped with two charging modules: on-board charger and DC-DC converter. This not only occupies a space in the vehicle but also an expensive part such as a high-speed switching circuit is used repeatedly.

Republic of Korea Patent Publication No. 10-2012-0007663 (2012.01.25.)

A charging system that can be used in an electric vehicle is presented. The charging system presented combines the charging circuit of the driving high voltage battery of the electric vehicle and the charging circuit of the low voltage battery for the electric field into one charging system. The proposed charging system reduces the cost by integrating the redundant and expensive components included in the two charging circuits. The proposed charging system also ensures safe and stable operation of the circuit and reduces the weight and volume of parts to improve mileage and vehicle mounting.

The presented charging system also allows for the adoption of low cost and miniaturized components by lowering the capacity of the components through placement and adjustment of the respective circuits.

The charging system for an electric vehicle according to the above-described aspect and to achieve an additional object includes an external input rectifying unit rectifying an external AC input and outputting the same to an output terminal, and converting the DC voltage input to the input terminal at high speed to high frequency AC. The high speed switching unit outputting the high frequency AC voltage outputted from the high speed switching unit to the first conversion ratio and outputting the high frequency AC voltage outputted from the high speed switching unit or reducing the high frequency AC voltage output from the high speed switching unit to the first conversion ratio. A transformer unit for converting to a second conversion ratio and outputting to a low voltage output stage, a high voltage smoothing unit for converting and outputting an alternating current output from the high voltage output stage of the transformer unit to a DC voltage for charging a high voltage battery, and a low voltage output stage of the transformer unit AC output from DC A switching comprising a low voltage smoothing unit which converts into a DC current for smoothing and charging a low voltage battery and outputs it to an output terminal, and a first switching unit selectively connecting one of an output terminal of an external input rectifying unit and a terminal of a high voltage battery to an input terminal of the high speed switching unit. And a first switching control unit for controlling the switching of the switching unit to connect the output terminal of the external input rectifying unit to the input terminal of the high speed switching unit in the high voltage battery charging mode, and the terminal of the high voltage battery to the input terminal of the high speed switching unit in the low voltage battery charging mode. It may include a switching controller including.

According to another aspect, the transformer section has a common single core, a common primary side coil wound on the core and constituting the input stage, a secondary side coil for high voltage wound on the core and constituting the high voltage output stage, and a low voltage output stage wound on the core. It may include a secondary side coil for low voltage.

According to a further aspect, in the secondary coil for low voltage, two windings having the same number of turns may be connected to a current doubler.

According to another aspect, the external input rectifier is a full-wave rectifier for rectifying the external AC input, and the power factor for adjusting the phase of the full-wave rectified pulsating current and the voltage, smoothing the voltage and stepping up to a voltage level suitable for charging a high voltage battery. The control booster may include a power factor correction booster.

According to the auxiliary aspect, the peak DC voltage of the input DC voltage and the output high frequency AC of the high speed switching unit may be substantially the same.

According to another aspect, the switching unit is a second switching unit for switching the connection of the output of the high voltage output terminal of the transformer unit and the input terminal of the high voltage smoothing unit, and the third switching unit for switching the connection of the output of the low voltage output terminal of the transformer unit and the input terminal of the low voltage smoothing unit The switching control unit may further include a second switching control unit connecting the second switching unit and disconnecting the third switching unit in the high voltage battery charging mode, and disconnecting the second switching unit and connecting the third switching unit in the low voltage battery charging mode. Can be.

According to a further aspect, the switching control unit may be configured with a single integrated control logic for controlling the interruption of each switching unit.

The proposed charging system reduces the cost by integrating the redundant and expensive components included in the two charging circuits. Yet the charging system presented ensures safe and stable operation of the circuit.

The proposed charging system also allows the adoption of low cost and miniaturized components by lowering the capacity of the components through placement and adjustment of the circuits of the power converter. Integration of the control unit reduces the use of expensive components such as microprocessors. It is also possible to reduce the volume and weight of the transformer as well as to make the structure for heat dissipation small and simple. In addition, sharing expensive, high-speed switching circuits not only reduces component costs, but also reduces the cost of heat dissipation structures that handle the heat generated by those circuits.

1 is a block diagram schematically illustrating a configuration of a charging system for an electric vehicle according to an embodiment.
2 illustrates an embodiment of the first switching unit.
FIG. 3 illustrates a state in which a circuit is connected in a high voltage battery charging mode in the embodiment shown in FIG. 1.
FIG. 4 illustrates a state in which a circuit is connected in a low voltage battery charging mode in the embodiment shown in FIG. 1.
FIG. 5A shows the current flow in the circuit of this current doubling device, and FIG. 5B shows the waveform of each part's signal in FIG. 5A.
6A shows the appearance of a lower core of a common core according to one embodiment.
FIG. 6B is a diagram illustrating an example in which coils are wound adjacent to each other in a vertical direction to a core in a transformer unit according to an embodiment.
6C illustrates an equivalent circuit of a transformer according to one embodiment.

The foregoing and other additional objects will become apparent through the following description of the embodiments. Aspects described in each claim can be combined so as to constitute various inventions independently and mutually coupled as long as they are not technically contradictory. It is to be understood that the following embodiments are illustrative of the various inventions.

1 is a block diagram schematically illustrating a configuration of a charging system 10 for an electric vehicle according to an embodiment. As shown, the charging system 10 for an electric vehicle according to an embodiment of the present invention is an external input rectifier 100 for rectifying and outputting an external AC input to an output terminal, and a high frequency AC by switching a DC voltage input to the input terminal at high speed. Converts the output AC voltage of the high speed switching unit 200 and the output AC voltage of the high speed switching unit 200 into a first conversion ratio and outputs the output AC voltage to the high voltage output terminal, or outputs the output AC voltage of the high speed switching unit 200. The high voltage battery 31 is charged by smoothing an alternating current outputted from the high voltage output terminal of the transformer unit 300 and the transformer unit 300 which is converted to a second conversion ratio that is a decompression ratio rather than one conversion ratio and outputs to the low voltage output terminal. High voltage smoothing unit 400 to convert the DC current to the output and the alternating current output from the low voltage output terminal of the transformer unit 300 by smoothing the low voltage batter The low voltage smoothing unit 500 converts the DC current to charge the output 33 and outputs it to the output terminal, one of the output terminal of the external input rectifying unit 100 and the terminal of the high voltage battery 31 at the input terminal of the transformer unit 300. And a switching unit 600 including a first switching unit 610 selectively connecting the switching unit, and controlling the switching of the switching unit 600 to connect the output terminal of the external input rectifying unit to the input terminal of the fast switching unit in the high voltage battery charging mode. In the low voltage battery charging mode, the switching controller 700 may include a first switching controller 710 connecting a terminal of the high voltage battery 31 to an input terminal of the fast switching unit.

In an embodiment, the external input rectifier 100 may include a full bridge rectifier. Preferably, the front end of the external input rectifier 100 may further include an EMI filter. Unlike the rapid charging mode in which a high-capacity direct current is injected, the external input is the commercial AC power in the continuous charging mode.

According to another aspect, the external input rectifier 100 adjusts the phase of the full-wave rectifier and the full-wave rectified pulsating current and the voltage to match the phase of the full-wave rectified pulsating current, and smooth the voltage to a voltage level suitable for charging the high voltage battery The booster may include a power factor correction booster (PFC). The power factor regulating booster is a circuit that smoothes the input current by switching the choke coil and the capacitor to control the charging and discharging, and adjusts the duty cycle ratio of the switching to match the voltage and phase. In one embodiment, the commercial voltage of single-phase 220V has a peak voltage of 311V, which is slightly boosted such that the maximum value of the output terminal voltage in the power factor adjusting booster is similar to the DC 400V maximum voltage of the high voltage battery.

The high speed switching unit 200 drives four switches to PWM to convert the DC voltage inputted to the input terminal into high frequency AC, 200K square wave AC in this embodiment. In the illustrated embodiment, the peak DC voltage of the high speed switching unit 200 and the output high frequency AC are substantially the same. As will be described later, the operation of the fast switching unit 200 remains the same even in the charging mode of the low voltage battery, thereby facilitating the integrated use of components.

This high speed switching of the DC-DC converter reduces the capacity of the transformer of the rear stage and ensures that the DC output of the final stage has adaptive stability to the load. In the slow charging mode of the high voltage battery 31, the input terminal of the fast switching unit 200 is connected to the output terminal of the external input rectifying unit 100. In the charge mode of the low voltage battery 33, the input terminal of the fast switching unit 200 is connected to the terminal of the high voltage battery 31.

The transformer unit 300 converts the output AC voltage of the high speed switching unit 200 into a first conversion ratio and outputs the output AC voltage to the high voltage output stage, or reduces the output AC voltage of the high speed switching unit 200 to the first conversion ratio. It converts into a 2nd conversion ratio and outputs it to the low voltage output stage. In the illustrated embodiment, three coils may be wound around the common core of the transformer unit 300. The transformer unit 300 is a combination of two transformers. In the illustrated embodiment, the transformer unit 300 includes a common single core, a common primary side coil wound around the core and forming an input stage, a secondary side coil for high voltage winding around the core and forming a high voltage output stage, and a core. It may include a secondary coil for low voltage wound and constituting a low voltage output stage. This integrated transformer has the advantage of reducing the cost and size of the system.

However, the present invention is not limited thereto, and the transformer unit 300 may be implemented as two separate transformers in which primary and secondary coils having different turns ratios are wound around each core. In the illustrated embodiment, the turns ratio of the primary coil and the secondary coil for high voltage is 12:12. The turns ratio of the primary side coil and the low side secondary coil may correspond to the ratio of the terminal voltage of the high voltage battery and the charging voltage of the low voltage battery, which in the illustrated embodiment is 12: 1.

According to a further aspect, in the secondary coil for low voltage, two windings having the same number of turns may be connected to a current doubler. In the illustrated embodiment, the low voltage smoothing unit 500 has two dual half bridge rectifiers connected to the low voltage secondary coils and the current doubler of the transformer unit 300. This embodiment will be described in more detail later with reference to FIG. 4.

The high voltage smoothing unit 400 converts the alternating current output from the high voltage output terminal of the transformer unit 300 into direct current to convert the direct current into a direct current to charge the high voltage battery 31. In one embodiment, the high voltage smoothing unit 400 includes a full bridge rectifier 410 and an LC filter 430. The low voltage smoothing unit 500 converts the alternating current output from the low voltage output terminal of the transformer unit 300 into direct current to charge the low voltage battery 33 and outputs it to the output terminal.

The switching unit 600 includes a first switching unit 610 selectively connecting one of an output terminal of the external input rectifying unit 100 and a terminal of the high voltage battery 31 to an input terminal of the high speed switching unit 200. The switching controller 700 controls the switching of the switching unit 600 to connect the output terminal of the external input rectifying unit to the input terminal of the high speed switching unit in the high voltage battery charging mode, and the high voltage battery 31 to the input terminal of the high speed switching unit in the low voltage battery charging mode. The first switching control unit 710 for connecting the terminal of the.

In particular, in the first switching unit 610, the input terminals C11 and C12 of the high speed switching unit 200 are the output terminals C01 and C02 of the external input rectifying unit 100 and the terminals C71 and C72 of the high voltage battery 31. It is important to configure the first switching unit 610 to be connected to only one of them. 2 illustrates an embodiment of such a first switching unit 610. If the input terminals C11 and C12 of the high speed switching unit 200 are connected to the output terminals C01 and C02 of the external input rectifier 100 and the terminals C71 and C72 of the high voltage battery 31 at the same time, the commercial power source may be In a state converted to direct current, it may be directly supplied to the high voltage battery 31 to cause a short circuit.

According to another aspect, the switching unit 600 is a second switching unit 630 for switching the connection of the output of the high voltage output terminal of the transformer unit 300 and the input terminal of the high voltage smoothing unit 400, and the transformer unit 300 The switching device 700 further includes a third switching unit 650 for switching the output of the low voltage output terminal and the input terminal of the low voltage smoothing unit 500, and the switching control unit 700 in the high voltage battery charging mode. And a second switching controller 730 for disconnecting the third switching unit 650 and for disconnecting the second switching unit 630 and connecting the third switching unit 650 in the low voltage battery charging mode. .

According to another aspect, the switching unit 600 further includes a fourth switching unit 670 for switching the connection of the output terminal of the high voltage smoothing unit 400 and the terminals of the high voltage battery 31, and the switching control unit 700. ) May further include a third switching controller 750 connecting the fourth switching unit 670 in the high voltage battery charging mode and cutting off the fourth switching unit 670 in the low voltage battery charging mode. In one embodiment, the switching unit 600 may be arranged in a detachable structure so as to be integrated into a relay fastening portion of a junction box in an integrated electric vehicle charging system assembly to replace a failed relay. However, the present invention is not limited thereto, and the switching unit 600 may be implemented with various switching elements such as a MOSFET, an IGBT, a transistor, a FET, a triac, an SSR, a GTO, a magnet contactor, and the like.

According to a further aspect, the switching control unit 700 may be configured with a single integrated control logic to control the interruption of each switching unit. The switching controller 700 outputs a switching control signal to the plurality of output terminals for controlling the gate voltage of the relay in accordance with a timing selection input according to one of the high voltage battery charging mode and the low voltage battery charging mode. In one embodiment, the switching controller 700 consists of a single microprocessor and an output terminal board for outputting contact signals.

3 illustrates a state in which a circuit is connected by the switching controller 700 in the high voltage battery charging mode in the embodiment shown in FIG. 1. In the illustrated embodiment, in the high voltage battery charging mode, the output AC voltage of the fast switching unit 200 is input to the primary coil of the transformer unit 300 and output from the secondary coil for high voltage. The primary and secondary circuits are separated by the transformer unit 300. In this embodiment, since the input has been sufficiently amplified in the front end, i.e., in the PFC circuit of the external input rectifier 100 or possibly in the fast switching section 200, the transformer section 300 has a 1: 1 ratio in the high voltage battery charging mode. It may have a turns ratio. In addition, since the input is high frequency AC, the size of the transformer unit 300 can be reduced. The output of the high voltage secondary coil of the transformer unit 300 is converted into a stable direct current in the high voltage smoothing unit 400 and supplied to the high voltage battery.

In this circuit, the output terminal voltage of the external input rectifying unit 100 is referred to as V-PFC, the output voltage supplied to the high voltage battery is referred to as VH_BAT, and the number of turns of the primary side coil and the high side voltage secondary coil of the transformer unit 300 is Let N be the N1 and N2, respectively, and the duty ratio of the fast switching unit 200 is D,

Is established. By this formula, the output voltage can be adjusted to be suitable for charging a high voltage battery.

In the illustrated embodiment, the boost is performed by the external input rectifier 100 so that the high speed switching unit 200 does not need to be substantially boosted, which controls the fast switching unit 200 in the high voltage battery charging mode and the low voltage battery charging mode. Simplify However, the present invention is not limited thereto, and the external input rectifier 100 may adjust power factor and rectify only, and implement the same operation by controlling the switching of the high speed switch 200 in both modes to adjust the boost ratio of the output. . Alternatively, the winding ratio of the transformer 300 may be changed and implemented. Furthermore, it is possible by the combination of these.

FIG. 4 illustrates a state in which a circuit is connected by the switching controller 700 in the low voltage battery charging mode in the embodiment shown in FIG. 1. In the illustrated embodiment, the input of the fast switching unit 200 is connected to the terminal of the high voltage battery in the low voltage battery charging mode. In addition, the output AC voltage of the high speed switching unit 200 is input to the primary coil of the transformer unit 300 and output from the secondary coil for low voltage. The output of the low voltage secondary coil of the transformer unit 300 is converted into a stable direct current in the low voltage smoothing unit 500 and supplied to the high voltage battery.

According to a further aspect, in the secondary coil for low voltage, two windings having the same number of turns may be connected to a current doubler. In the embodiment shown in FIG. 4, the low voltage smoothing unit 500 includes two half half rectifier circuits as secondary voltage coils and current doublers for the low voltage of the transformer unit 300. Will be wired.

FIG. 5A shows the current flow in the circuit of this current doubling device, and FIG. 5B shows the waveform of each part's signal in FIG. 5A. As shown, in the positive side of the transformer, the D1 diode is forward biased and the voltage across TR1 is transmitted to the output filter. In the negative section, the D2 diode is forward biased and the TR2 The negative value of the voltage is passed to the output filter. This connection reduces the size of the transformer and stabilizes the output by dividing the current supplied to the low voltage battery or the electrical system by half.

6A shows the appearance of a lower core of a common core according to one embodiment. The common core is assembled by winding each coil around this lower core and then closing the core cap. FIG. 6B is a diagram illustrating an example in which coils are wound adjacent to each other in a vertical direction to a core in a transformer unit according to an embodiment. 6C illustrates an equivalent circuit of a transformer according to one embodiment.

In the circuit shown in FIG. 4, the terminal voltage of the high voltage battery is called VH_BAT, the output voltage supplied to the low voltage battery is called VL_BAT, and the number of turns of the primary coil and the low voltage secondary coil of the transformer unit 300 is N3, respectively. , N4, and the duty ratio of the fast switching unit 200 is D,

Is established. By this formula, the output voltage can be adjusted to suit the charge of the low voltage battery.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and similar arrangements that may occur to those skilled in the art.

100 External input rectifier 200 High speed switching unit
300 Transformer Section 400 High Voltage Smoothing Section
500 low voltage smoothing part 600 switching part
700 switching controller

Claims (7)

In a charging system for an electric vehicle, the charging system is:
An external input rectifier for rectifying the external AC input and outputting the rectified output signal to an output terminal;
A high speed switching unit for converting a DC voltage input to the input terminal at high speed to convert the DC voltage into a high frequency AC and output the same;
The high frequency AC voltage output from the high speed switching unit is converted into a first conversion ratio and output to the high voltage output stage, or the high frequency AC voltage output from the high speed switching unit is converted into a second conversion ratio which is a decompression ratio than the first conversion ratio and low voltage. A transformer unit for outputting to an output terminal;
A high voltage smoothing unit converting the alternating current output from the high voltage output terminal of the transformer unit into a direct current to convert the direct current into a direct current to charge the high voltage battery;
A low voltage smoothing unit converting the alternating current output from the low voltage output terminal of the transformer unit into a direct current to convert the direct current into a direct current to charge the low voltage battery;
A switching unit including a first switching unit selectively connecting one of an output terminal of the external input rectifying unit and a terminal of the high voltage battery to an input terminal of the high speed switching unit;
The switching of the switching unit is controlled to connect the output terminal of the external input rectifier to the input terminal of the high speed switching unit in the high voltage battery charging mode, and the high voltage battery terminal is connected to the input terminal of the high speed switching unit in the low voltage battery charging mode. And a switching control unit including a first switching control unit for enabling use in the low voltage battery charging mode, respectively.
Charging system for an electric vehicle comprising a.
The method of claim 1, wherein the transformer unit:
With a common single core,
A common primary coil wound around the core and constituting the input stage;
A secondary coil for high voltage wound around the core and constituting a high voltage output stage;
A charging system for an electric vehicle, comprising a low voltage secondary side coil wound around a core and constituting a low voltage output stage.
The charging system for an electric vehicle according to claim 2, wherein the secondary coil for the low voltage has two windings having the same number of turns as a current doubler.
The method of claim 1, wherein the external input rectifier is:
Full wave rectifier for rectifying external AC input,
A charging system for an electric vehicle including a power factor correction booster for adjusting the phase of the full-wave rectified pulsating current to match the voltage, smoothing the voltage, and boosting the voltage of the high voltage battery.
The charging system for an electric vehicle according to claim 4, wherein the input DC voltage of the high speed switching unit and the peak voltage of the output high frequency AC are substantially the same.
The method of claim 1, wherein the switching unit:
A second switching unit for switching a connection between an output of the high voltage output terminal of the transformer unit and an input terminal of the high voltage smoothing unit;
A third switching unit for switching the connection of the output of the low voltage output stage of the transformer unit and the input terminal of the low voltage smoothing unit,
The switching control is:
And a second switching control unit connecting the second switching unit and the third switching unit in the high voltage battery charging mode, and disconnecting the second switching unit and connecting the third switching unit in the low voltage battery charging mode.
6. The charging system of an electric vehicle according to claim 5, wherein the switching control unit is composed of a single integrated control logic for controlling the interruption of the respective switching units.

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