KR20190115364A - Single and three phase combined charger - Google Patents

Abstract

The present invention relates to a charger in which a single phase and a three phase are combined. The charger in which the single phase and the three phase are combined comprises: a phase voltage selector which performs switching according to a case where the input power is single phase or three phase; three single phase power factor improving converters connected to the phase voltage selector by each phase; and a DC/DC converter performing charge control by connecting an output terminal of three single phase power factor improving converters, wherein the phase voltage selector forms and changes a connection between the input power supply and the three single phase power factor improving converters through switching and then supplies input power of the single phase or the three phase to at least one of the three single phase power factor improving converters.

Description

Single and three phase combined chargers {Single and three phase combined charger}

The present invention relates to a single-phase and three-phase combined charger.

The slow charger of an electric vehicle battery uses a commercial power supply as an input, and a single-phase input is used for 7 kW or less, and a three-phase input for more than that. The structure basically consists of a power factor correction converter for power factor correction (PFC) and an isolated DC / DC converter for isolation and charge control.

1 is a view showing the structure of a conventional single-phase charger, Figures 2 to 4 is a view showing the structure of a conventional three-phase charger.

The three-phase charger shown in FIG. 2 is implemented by applying the structure of the single-phase charger shown in FIG. 1 for each phase. And, the three-phase charger shown in Figure 3 has a structure using a three-phase unidirectional PFC converter and an isolated DC / DC converter. In addition, the three-phase charger shown in FIG. 4 has a structure using a three-phase inverter as a power factor improving converter instead of the three-phase unidirectional PFC converter of FIG. 3.

In the three-phase charger of FIG. 2, since the primary sides of the three single-phase converters must each have a separate ground (GND), the DC link capacitors cannot be shared, and all of them must be individually controlled, so that the control structure is complicated. Do. However, when the three-phase charger of FIG. 2 uses a phase voltage instead of a line voltage as a three-phase input, the breakdown voltage of the switching element is lowered, so that a MOSFET capable of high frequency switching can be used to maintain efficiency and reduce the size of the magnetic element. .

The charger of FIGS. 3 and 4 is simpler than the charger structure of FIG. 2, but cannot use a phase voltage and use only a line voltage, thereby increasing the breakdown voltage of the switching element. Thus, the chargers of FIGS. 3 and 4 must use IGBTs with low switching speeds, and thus are not suitable for electric vehicles requiring a small charger due to a large volume of magnetic elements.

In addition, the three-phase charger of FIGS. 2 to 4 has a problem in that it is difficult to achieve high efficiency since the power factor improving converter is commonly configured in a hard switching scheme.

The present invention is to provide a single-phase and three-phase combined charger using an isolated power factor improving converter.

According to an aspect of the present invention, a single-phase and three-phase charger using a power factor improving converter is disclosed.

In the single-phase and three-phase combined charger according to the embodiment of the present invention, a phase voltage selector for performing switching according to the case where the input power is single phase or three phase, three single-phase power factor improving converter connected to each of the phase voltage selector, and the three And a DC / DC converter connected to an output terminal of the single phase power factor improving converter to perform charge control, wherein the phase voltage selector forms and changes a connection between the input power and the three single phase power factor improving converter through the switching. Thus, the input power is supplied to at least one of the three single-phase power factor improving converters.

When the input power is three-phase, the phase voltage selector configures the connection such that each of the three-phase input power is input to each single-phase power factor improving converter through the switching.

When the input power is single phase, the phase voltage selector configures the connection such that the single phase input power is input to each single phase power factor improving converter through the switching.

When the input power is single phase, the phase voltage selector configures the connection such that the single phase input power is input to two single phase power factor improving converters among the three single phase power factor improving converters through the switching.

When the input power is single phase, the phase voltage selector configures the connection such that the single phase input power is input to one single phase power factor improving converter of the three single phase power factor improving converters through the switching.

And three single-phase bridge diodes rectifying the input power delivered from the phase voltage selector and inputting the three single-phase power factor improving converters.

The three single-phase power factor improving converter may include a transformer, a first switch and a second switch connected to one end of the primary of the transformer and operating complementarily, and a third switch connected to and connected to the other ends of the transformer. And a fourth switch, connected to the secondary side of the transformer to control the output voltage, and a fifth switch having a back-to-back structure, connected to the secondary side of the transformer, and commonly used DC link capacitor (DC). link capacitors, wherein the output stages of the three single-phase power factor improving converters are on the secondary side of the transformer.

As the first to fourth switches operate at a fixed frequency to convert the input power into high frequency, a high frequency transformer is used.

The fifth switch is PWM controlled, the primary voltage of the transformer changes in accordance with the on / off operation of the fifth switch, the current flowing in the primary side of the transformer is discontinuous mode (DCM: Discontinuous mode), the control of the output voltage is performed.

The single-phase and three-phase combined charger using the insulated power factor improving converter according to the embodiment of the present invention can minimize the switching loss of the primary side switch to increase the frequency even in the switching of the high voltage to reduce the size of the magnetic device.

In addition, the control is carried out only on the secondary side, and the control is simple by not performing current control for improving the power factor.

In addition, the size of the DC link capacitor can be shared.

1 is a view showing the structure of a conventional single-phase charger.
2 to 4 is a view showing the structure of a conventional three-phase charger.
5 is a view schematically showing the configuration of a single-phase and three-phase combined charger according to an embodiment of the present invention.
6 is a diagram illustrating a circuit of a single-phase and three-phase charger according to an embodiment of the present invention.
Fig. 7 is a diagram showing an operation waveform of the single-phase isolated power factor improving converter of A phase.
8 is a diagram showing an operation mode of an insulated power factor improving converter of A phase;
FIG. 9 is a diagram for explaining the operation of a waveshaper; FIG.
10 shows an example of the operation of a phase voltage selector.
11 to 14 is a view showing the simulation results of the single-phase and three-phase combined charger according to an embodiment of the present invention.
15 and 16 are circuit diagrams of a single-phase and three-phase charger according to another embodiment of the present invention.

As used herein, the singular forms "a", "an" and "the" include plural forms unless the context clearly indicates otherwise. In this specification, terms such as “consisting of” or “comprising” should not be construed as necessarily including all of the various components or steps described in the specification, and some of the components or some steps It should be construed that it may not be included or may further include additional components or steps. In addition, the terms "... unit", "module", etc. described in the specification mean a unit for processing at least one function or operation, which may be implemented in hardware or software or a combination of hardware and software. .

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

5 is a view schematically showing the configuration of a single-phase and three-phase charger charger according to an embodiment of the present invention, Figure 6 is a view showing a circuit of a single-phase and three-phase charger charger according to an embodiment of the present invention.

5, the single-phase and three-phase charger according to an embodiment of the present invention is a phase selector (10), a single-phase bridge diode (20), single-phase isolated power factor converter (30) and non-isolated DC / DC converter 40 is included.

In the single-phase and three-phase combined charger according to the embodiment of the present invention, since the power factor improving converter is insulated, the single phase isolated power factor improving converter 30 is classified by phases, and the output terminal of the single phase isolated power factor improving converter 30 is Since it exists on the secondary side of the transformer, a DC link capacitor can be commonly used.

The non-isolated DC / DC converter 40 performs charge control using the DC voltage of the DC link capacitor. For example, the non-isolated DC / DC converter 40 may be a buck converter, a boost converter, a buck boost converter, or the like.

The phase voltage selector 10 performs switching according to the case where the input power source is single phase or three phase to supply the single phase or three phase input power to at least one of the three single phase isolated power factor improving converters 30.

The single phase bridge diode 20 rectifies the input power supplied from the phase voltage selector 10 and transmits the rectified power to the single phase isolated power factor improving converter 30.

The circuit diagram of Fig. 6 shows an example of a three-phase three-wire charger for both single-phase and three-phase.

Referring to FIG. 6, each single phase insulated power factor improving converter 30 includes a front end circuit 31, a transformer 32, a rear end circuit 33, a transformer control unit 34, and an output terminal 35.

The front end circuit 31 refers to circuits located at the front end (position close to the voltage source) of the transformer 32 and includes a capacitor C and switches M ₁ and M ₂ . Voltage is used as the input source of the front end circuit 31.

The capacitor C is connected with the voltage source and connected in parallel with respect to the switches M ₁ and M ₂ .

The switch M ₁ is connected to the node n _1, that is, _one end of the capacitor C.

The switch M ₂ may be connected in series with the switch M ₁ based on the node n1, and may be connected in parallel with the switch M ₁ based on the transformer 32.

The switches M ₁ and M ₂ operate complementarily. For example, when the switch M ₁ is ON, the switch M ₂ is OFF, and when the switch M ₁ is OFF, the switch M ₂ is ON.

One end of the primary side of the transformer 32 is connected to the node n2 between the switches M ₁ and M ₂ , and the other end of the primary side is connected to the inductor L _r . That is, the inductor L _r is located at the rear end of the transformer 32 (a position far from the voltage source).

According to one embodiment, the transformer 32 may be controlled by the transformer control unit 34.

The transformer control unit 34 is connected to the secondary side of the transformer 32 and consists of a switch M ₅ having a back-to-back (B2B) structure as shown in FIG. 1. Here, the switch M ₅ is connected to the front end of the full bridge diode.

That is, the output voltage is controlled through PWM control using the switches M _5a , M _5b , and M _5c having a back-to-back structure. According to the on / off operation of the switches M _5a , M _5b , and M _5c , the voltage on the primary side of the transformer changes so that the current flowing in the primary side of the transformer flows in a discontinuous mode (DCM). At the same time, the desired output voltage can be controlled.

Since the circuits of the single-phase and three-phase chargers according to the embodiment of the present invention operate in the discontinuous mode, harmonic control of the input power is achieved without separate control, and only a voltage controller exists for voltage control. The output of the current controller is supplied to the switches M _5a , M _5b and M _5c by a PWM circuit.

Single- and three-phase charger circuits are unlikely to have high power factor greater than 0.96 when operating in discontinuous mode, so the Waveshaper uses the input and output voltage information to make each phase's input power an ideal sine wave.

The rear end circuit 33 is located at the rear end of the primary side of the transformer 32 and may include an inductor L _r and a plurality of switches M ₃ and M ₄ .

One end of the inductor L _r is connected to the other end of the primary side of the transformer 32, and the other end is connected to the node n3 between the switches M ₃ and M ₄ .

Switches M ₃ and M ₄ operate complementarily. For example, when the switch M ₃ is ON, the switch M ₄ is OFF, and when the switch M ₃ is OFF, the switch M ₄ is ON.

For example, the switches M _1a , M _1b , M _1c to M _4a , M _4b , and M _4c of each single-phase isolated power factor improving converter 30 operate at a fixed frequency with a ratio of 50% to generate high frequency input power. Because of the conversion, a high frequency transformer can be used.

The output terminal 35 may consist of a full bridge diode and an output capacitor. Here, the full bridge diode is composed of diodes D ₁ to D ₄ and may perform a rectifying function. Of course, a half bridge diode may be used instead of the full bridge diode.

The output capacitor is connected in parallel to the full bridge diode.

Although not shown, a DC-coupling capacitor may be added in series with the transformer 32 to remove the DC bias component of the voltage applied to the transformer 32. In this case, saturation of the transformer 32 can be prevented.

FIG. 7 is a diagram showing an operation waveform of the single-phase isolated power factor improving converter of A phase, and FIG. 8 is a diagram showing an operation mode of the isolated power factor improving converter of A phase.

Since the three single-phase insulated power factor improving converter 30 applied to each single-phase and three-phase charger according to an embodiment of the present invention is similar in operation, only the operation of the A-phase single-phase insulated power factor improving converter 30 will be described. Let's do it.

The switches M _1a and M _3a and the switches M _2a and M _4a are simultaneously turned on and off, and the switch M _5a is the time point at which the switches M _1a and M _3a and the switches M _2a and M _4a are turned on as shown in FIG. 7. It works at the same time.

Referring to Mode 1 (t ₀ <t <t ₁ ) illustrated in FIGS. 7 and 8, when the switches M _1a , M _3a, and M _5a are turned on at time t ₀ , the primary inductor current i _pa is shown in FIG. 8. Start to flow in the same path as mode 1.

In this case, the transformer primary side voltage V _pa becomes zero so that the transformer primary side inductor current i _pa increases linearly with the slope of V _in (input voltage) / L _r (inductance of the inductor in series connected to the transformer primary side). The diodes D _1a to D _4a are off and no current flows to the output terminal. The input current I _{in in} mode 1 can be represented by the following equation.

Referring to the mode 2 (t ₁ <t <t ₂ ) illustrated in FIGS. 7 and 8, when the switch M _5a is turned off at the time t ₁ , the diodes D _1a and D _3a as in the mode 2 of FIG. 8. Is conducted and V _o / n is applied to the transformer primary side voltage V _pa . Here, V _o / n is formed to a voltage larger than the input voltage, n is the turns ratio. Due to this, the primary inductor current i _pa decreases linearly with a slope of (V _in -V _o / n) / L _r , which can be represented by the following equation.

Referring to mode 3 (t ₂ <t <t ₃ ) illustrated in FIGS. 7 and 8, when the input current I _in drops from mode 2 to 0, mode 3 starts and the converter operation is stopped.

Modes 4 through 6 of the remaining half cycle operate similarly to modes 1 through 3.

9 is a view for explaining the operation of the waveform (Waveshaper).

The waveform shown in FIG. 9 represents the peak value of the line current i _ac and the input current I _{in_a} during the half period, (a) when the waveform controller is present, and (b) where the waveform controller is not present. If it is.

As shown in FIG. 9A, in the absence of the waveform regulator, the peak value of the input current I _{in_a} follows the input voltage, but the line current i _ac is distorted.

On the other hand, as shown in (b) of FIG. 9, when there is a waveform controller, the peak value of the input current I _{in_a} can be distorted to form the final line current as a sinusoidal wave without distortion. The rate of application for forming the input current into the ideal sinusoidal wave can be expressed by the following equation.

Referring to Equation 3, the final application rate generated through PWM control is expressed as the product of the term D _oA according to the load condition and the waveshaping term using the input voltage and the battery voltage.

The single-phase isolated power factor improving converter 30 according to the embodiment of the present invention can operate without a waveform regulator, but the waveform regulator can be applied when additional power factor improvement is required.

10 is a diagram illustrating an operation example of a phase voltage selector.

Referring to FIG. 10, the phase voltage selector 10 includes four switches, and forms a connection between a single-phase or three-phase input power supply and three single-phase insulated power factor improving converter 30 using four switches. And can be changed. For example, the four switches may be relays or semiconductor switches.

As shown in FIG. 10, the phase voltage selector 10 may perform the switching operation in all four cases according to the phase voltage condition.

That is, when the switches 1 and 3 (Rly1 and Rly3) are turned on, a connection using three-phase input power is configured so that each of the three-phase input power can be input to each single-phase insulated power factor improving converter 30.

Then, when the switches 2 and 4 (Rly2, Rly4) is turned on, is a connection to all use the configuration of a single-phase input power source V _ab of the three-phase isolated type power factor improving converter 30 and the single-phase input power source V _ab, each It may be input to the single-phase insulated power factor improving converter 30.

And, if the switch 4 or switch-2-one, is the connection used by the two of the single-phase input power source V _ab 3 single-phase insulated power factor improving converter (30) configuration, the single-phase input power source V _ab two-phase It may be input to the isolated power factor improving converter 30.

Then, when the four switches are all off, and the connection to the single-phase input power source V _ab using 3 eseoman one of the single-phase insulated power factor improving converter (30) configuration, the single-phase input power source V _ab is a single-phase isolated The power factor improving converter 30 may be input.

11 to 14 are diagrams showing the simulation results of the single-phase and three-phase combined charger according to an embodiment of the present invention.

For the simulation, the inductance L _r = 40 uH of the inductor in series connected to the transformer primary side and the transformer turns ratio were set to 1.2: 1, and a buck converter was used for the non-isolated DC / DC converter 40.

As shown in Figs. 11 to 14, the input current shows an ideal sine wave shape, and it is confirmed that it works well even with input voltages of single phase and three phases.

15 and 16 are circuit diagrams of a single-phase and three-phase charger according to another embodiment of the present invention.

15 and 16, the single-phase and three-phase combined charger according to another embodiment of the present invention is a three-phase four-wire type using a mid-islet point.

The embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art having ordinary knowledge of the present invention may make various modifications, changes, and additions within the spirit and scope of the present invention. Should be considered to be within the scope of the following claims.

10: Phase selector
20: single phase bridge diode
30: single-phase isolated power factor converter
40: non-isolated DC / DC converter

Claims (9)

A phase voltage selector for performing switching in the case where the input power source is single phase or three phase;
Three single-phase power factor improving converters connected to the phase voltage selector and each phase; And
A DC / DC converter connected to the output stages of the three single-phase power factor improving converter to perform charge control;
The phase voltage selector is configured to supply single-phase or three-phase input power to at least one of the three single-phase power factor improving converters by forming and changing a connection between the input power and the three single-phase power factor improving converters through the switching. Single and three-phase chargers featuring.
The method of claim 1,
And the phase voltage selector configures the connection such that each of the three phase input powers is input to each single phase power factor improving converter through the switching.
The method of claim 1,
And the phase voltage selector is configured to connect the single phase input power to each single phase power factor improving converter through the switching, when the input power is single phase.
The method of claim 1,
And the phase voltage selector configures the connection such that the single phase input power is input to two single phase power factor improving converters among the three single phase power factor improving converters through the switching when the input power source is single phase. 3-phase charger.
The method of claim 1,
And the phase voltage selector configures the connection such that the single phase input power is input to one single phase power factor improving converter of the three single phase power factor improving converters through the switching. 3-phase charger.
The method of claim 1,
And a three single-phase bridge diode for rectifying the input power delivered from the phase voltage selector and inputting the three single-phase power factor improving converters.
The method of claim 1,
The three single-phase power factor improving converter,
Transformers;
A first switch and a second switch connected to one end of a primary side of the transformer and operating complementarily;
A third switch and a fourth switch connected to the other end of the transformer and reciprocally operated;
A fifth switch connected to the secondary side of the transformer to control the output voltage and having a back-to-back structure;
It includes a DC link capacitor (DC link capacitor) commonly used to be connected to the secondary side of the transformer,
Single-phase and three-phase charger, characterized in that the output stage of the three single-phase power factor improving converter is present on the secondary side of the transformer.
The method of claim 7, wherein
The first to fourth switches operate at a fixed frequency to convert the input power into high frequency, so that the transformer is a single-phase and three-phase charger, characterized in that a high frequency transformer is used.
The method of claim 7, wherein
The fifth switch is PWM controlled,
The output voltage is controlled by changing the primary voltage of the transformer according to the on / off operation of the fifth switch so that a current flowing in the primary side of the transformer flows in a discontinuous mode (DCM). Single-phase and three-phase combined charger characterized in that the control of the.

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