KR20220008741A - Power factor correction converter - Google Patents

Abstract

Provided is a power factor improvement converter. The power factor improvement converter comprises: an input inductor connected to a power source; an input unit connected to one end of the input inductor and including a first switch and second switch switching current flow generated from the power source; a resonant capacitor connected to a first node and second node of the input unit; a resonant inductor; an output unit including a third diode and an output terminal; and a current adjustment unit adjusting current flow generated from the input unit and including a first diode connected to a third node of the input unit and a second diode connected the second node. Accordingly, the present invention has little possibility of a misoperation as it is easy to drive an operation mode.

Description

Power Factor Correction Converter {POWER FACTOR CORRECTION CONVERTER}

The following description relates to a power factor correction converter. More specifically, the present invention relates to a power factor improving converter that has excellent power conversion efficiency by omitting a bridge diode, and is easy to operate in an operation mode, thereby reducing the possibility of malfunction.

International organizations such as EC and IEEE regulate harmonic currents by establishing standards for harmonic currents. In order to satisfy such harmonic regulation, a boost converter for power factor correction (PFC) is being used. The power factor improvement method using the power factor improvement converter has been commercialized to this day because of its high reliability and efficiency.

The Y capacitor is connected to reduce EMC (ElectroMagnetic Compatibility) noise generated by the power factor correction converter. A typical power factor correction converter includes a bridge diode to change an AC voltage generated by a power supply to a DC voltage. However, the bridge diode has a lot of loss in the circuit, so it is a major factor in reducing the efficiency of the power factor correction converter.

Therefore, a bridgeless power factor correction converter in which a bridge diode is omitted is being studied. However, in the existing bridgeless power factor correction converter, a high switching voltage of a high-frequency pulse is applied to the Y-capacitor, which causes a lot of noise, or the polarity of the AC input voltage is changed because the driving method of the switching elements must be changed according to the polarity of the input voltage. There is a possibility of malfunction at the time of a changing zero cross, and it is difficult to apply to a general-purpose PFC IC due to the complexity of the control.

US Registered Patent No. 8,363,434 (2013.01.29)

There is provided a power factor improving converter that has excellent power conversion efficiency by omitting a bridge diode and has a low possibility of malfunction due to easy operation in an operation mode.

According to one aspect, there is provided an input inductor connected to a power source, and an input unit including a first switch and a second switch connected to one end of the input inductor to switch the flow of current generated from the power source; an output unit connected to the first node and the second node of the input unit and including a resonant capacitor, a resonant inductor, a third diode, and an output terminal; and a current controller that controls the flow of current generated from the input part, and includes a first diode connected to a third node of the input part and a second diode connected to the second node.

The first node is located between the power source and the second switch, the second node is located between the first switch and the second switch, and the third node is located between the input inductor and the first switch. can do.

One end of the first diode is connected to the third node, the other end of the first diode is connected to a fourth node located between the resonance capacitor and the resonance inductor, and one end of the second diode is connected to the fourth node may be connected to and the other end of the second diode may be connected to the first node.

One end of the first diode is connected to the third node, the other end of the first diode is connected to the output terminal, and one end of the second diode is connected to a fourth node located between the resonance capacitor and the resonance inductor. and the other end of the second diode may be connected to the first node.

The first diode allows a current to flow from the third node to one of the fourth node and the output terminal, and the second diode controls the flow of current from the first node to the fourth node. can allow

The power source may generate an AC voltage, and the first switch and the second switch may periodically repeat an on/off operation together.

When the first switch and the second switch are in an on state, the current generated from the input unit does not flow through the first diode and the second diode, and the charge charged in the resonance capacitor is in resonance with the resonance inductor. may be transmitted to the output terminal.

When the first switch and the second switch are in an off state, the current generated from the input unit passes through any one of the first diode and the second diode and passes through any one of the first diode and the second diode. The resonant capacitor may be charged by the passing current.

When the first switch and the second switch are in an off state and the polarity of the AC voltage of the power source is positive, the current generated from the power source is the input inductance, the first diode, the resonance capacitor, and the second The current generated in the input inductor passing through the body diode of the two switches may pass through the first diode, the resonant inductor, and the third diode to be transmitted to the output terminal.

When the first switch and the second switch are in an off state and the polarity of the AC voltage of the power source is negative, the current generated from the power source passes through the second diode and the body diode of the first switch, The current generated in the input inductor may charge the resonance capacitor.

and a fourth diode having one end connected to the fifth node and the other end connected to the first node, and allowing a current in a direction from the first node to the fifth node, wherein the fifth node is the resonance inductor and the third diode.

The output terminal may include an output capacitor.

A charging capacity of the output capacitor may be greater than a charging capacity of the resonance capacitor.

The output terminal may further include an output resistor connected in parallel with the output capacitor.

According to at least one embodiment, it is possible to reduce heat generation and improve efficiency by omitting the bridge diode of the power factor improving converter. According to at least one embodiment, a low frequency voltage or a voltage having a low time change rate (dV/dt) may be applied to the Y-capacitor connected to the power factor improving converter to improve noise characteristics. According to at least one embodiment, it is possible to reduce the manufacturing cost of the power factor improving converter by simplifying the operation of the switches regardless of the polarity of the AC input voltage, thereby reducing the possibility of malfunction and enabling the use of a low-cost general-purpose PFC IC instead of a microprocessor. have.

The accompanying drawings for use in the description of the embodiments of the present invention are only a part of the embodiments of the present invention, and for those of ordinary skill in the art (hereinafter referred to as "those skilled in the art"), the invention Other drawings may be obtained based on these drawings without additional effort to
1 is a circuit diagram illustrating a power factor improving converter according to a comparative example.
2 is a circuit diagram illustrating a power factor improving converter according to another comparative example.
3 is a circuit diagram illustrating a power factor improving converter according to another comparative example.
4 is a circuit diagram illustrating a power factor improving converter according to an exemplary embodiment.
5 is a circuit diagram illustrating a modified example of the power factor improving converter shown in FIG. 4 .
6 is a conceptual diagram illustrating an operation method of the power factor improving converter when the first switch and the second switch are in an on state when the AC input voltage has a positive polarity.
7 is a conceptual diagram illustrating an operation method of the power factor improving converter when the first switch and the second switch are off when the AC input voltage has a positive polarity.
8 is a graph showing main operation waveforms of each part according to the operation of the first switch and the second switch when the AC input voltage has a positive polarity.
9 is a conceptual diagram illustrating an operation method of the power factor improving converter when the first switch and the second switch are on when the AC input voltage has a negative polarity.
10 is a conceptual diagram illustrating an operation method of a power factor improving converter when the first switch and the second switch are off when the AC input voltage has a negative polarity.
11 is a graph showing main operation waveforms of each part according to the operation of the first switch and the second switch when the AC input voltage has a negative polarity.
12 is a circuit diagram exemplarily showing that a Y-capacitor for removing common mode noise is connected to the power factor improving converter shown in FIG. 4 .
13 is a circuit diagram illustrating another modified example of the power factor improving converter shown in FIG. 4 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description of the present invention refers to the accompanying drawings, which show by way of illustration a specific embodiment in which the present invention may be practiced, in order to clarify the objects, technical solutions and advantages of the present invention. These embodiments are described in detail to enable those skilled in the art to practice the present invention.

Throughout this description and claims, the word 'comprise' and variations thereof are not intended to exclude other technical features, additions, components or steps. In addition, 'one' or 'an' is used to mean more than one, and 'another' is limited to at least a second or more.

In addition, terms such as 'first' and 'second' of the present invention are for distinguishing one component from other components, and unless it is understood to indicate an order, the scope of rights is limited by these terms. is not For example, a first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

When a component is referred to as being “connected” to another component, it may be directly connected to the other component, but it should be understood that another component may intervene. On the other hand, when it is mentioned that a certain element is "directly connected" to another element, it should be understood that the other element does not exist in the middle. Meanwhile, other expressions describing the relationship between elements, that is, “between” and “immediately between” or “neighboring to” and “directly adjacent to”, etc., should be interpreted similarly.

In each step, identification symbols (eg, a, b, c, etc.) are used for convenience of explanation, and identification codes do not describe the order of each step unless it necessarily results in logic, and each The steps may occur out of the order specified. That is, each step may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

Other objects, advantages and characteristics of the present invention will become apparent to a person skilled in the art, in part from this description, and in part from practice of the present invention. The following illustrations and drawings are provided by way of illustration and are not intended to limit the invention. Therefore, the details disclosed herein with respect to a specific structure or function are not to be construed in a limiting sense, but merely representative It should be interpreted as basic data.

Moreover, the invention encompasses all possible combinations of the embodiments indicated herein. It should be understood that various embodiments of the present invention are different but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention in relation to one embodiment. In addition, it should be understood that the position or arrangement of individual components in each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Accordingly, the detailed description set forth below is not intended to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all scope equivalents as those claimed. Like reference numerals in the drawings refer to the same or similar functions throughout the various aspects.

In this specification, unless indicated otherwise or clearly contradicted by context, items referred to in the singular encompass the plural unless the context requires otherwise. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

Hereinafter, in order to enable those skilled in the art to easily practice the present invention, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a circuit diagram illustrating a power factor improving converter according to a comparative example.

Referring to FIG. 1 , the power factor improving converter 12 and the Y-capacitor 14 may be connected. The power factor correction converter 12 may include a bridge diode for converting an AC voltage into a DC voltage. In the circuit shown in FIG. 1 , since a low-frequency voltage (eg, an AC voltage of about 60 Hz) is applied to the voltage applied to the Y-capacitor as an input voltage, noise characteristics may be excellent. However, a large amount of heat loss may occur in the bridge diode. In addition, the efficiency of the power factor improving converter 12 may decrease due to the bridge diode. The decrease in the efficiency of the power factor correction converter 12 may be particularly serious when the magnitude of the input voltage is small.

2 is a circuit diagram illustrating a power factor improving converter according to another comparative example.

Referring to FIG. 2 , the power factor correction converter 22 may not include a bridge diode. The power factor correction converter 22 may include an input inductor L _in , switches M1 and M2 , and diodes D _o1 , D _o2 . The power factor correction converter 22 may convert an AC voltage into a DC voltage without a bridge diode. However, since a high switching voltage of a high frequency pulse having a large voltage change rate (dv/dt) with time is applied to the Y-capacitor 24 , the noise problem is serious, and thus commercialization is difficult.

3 is a circuit diagram illustrating a power factor improving converter according to another comparative example.

Referring to FIG. 3 , the power factor improving converter 32 may include an input inductor L _in , switches M1 and M2 , and diodes D _o1 , D _o2 . The power factor correction converter 32 may convert an AC voltage into a DC voltage without a bridge diode. When the power factor correction converter 32 shown in FIG. 3 is used, a low-frequency voltage (eg, an AC voltage of about 60 Hz), which is an input voltage, is applied to the Y-capacitor 34 , so that it can have low common-mode noise characteristics. However, for a normal operation, since the driving methods of the first switch M1 and the second switch M2 are different depending on the polarity of the input voltage, the timing at which the polarity of the input voltage is changed and the first switch M1 and the second switch M2 If the switching timings of the two switches M2 do not match, there is a possibility of malfunction and a decrease in power factor. Accordingly, a microprocessor and a voltage sensor for detecting the polarity of the AC input voltage may be required to precisely match the above-described switching timing and at the same time ensure proper operation according to the polarity of the AC input voltage. This requires the application of a complex algorithm and may increase the circuit cost.

4 is a circuit diagram illustrating a power factor improving converter according to an exemplary embodiment.

Referring to FIG. 4 , the power factor improving converter may include an input unit 110 , a current flow control unit 130 for controlling the flow of current generated from the input unit 110 , and an output unit 120 .

The input unit 110 may include a power source V _AC , an input inductor L _in , a first switch M1 , and a second switch M2 . _{The body diode D b1} of the first switch M1 may be directed from the second node n2 to the third node n3 , and the body diode D _b2 of the second switch M2 is may be directed from the second node n2 to the first node n1. In other words, the first body diode (D _b2) of the switch (M1) the body diode (D _b1) and a second switch (M2) of each other may be directed in the opposite direction. The input inductor (L _in ) stores electrical energy supplied from the _{power source (VAC} ) when the first switch (M1) and the second switch (M2) are in an on state, and the first switch (M1) and the second switch (M2) 2 When the switch M2 is turned off, the stored electrical energy is transferred to the output unit 120 through the current flow control unit 130 .

The output unit 120 may be connected to the second node n2 and the first node n1 . The output unit 120 may include a resonant capacitor C _p connected to the second node n2 , a resonant inductor L _r , a third diode D _A , and output terminals C _{o and} R _o . The output stage may comprise an output capacitor (C _o) and the output resistance (R _o), the output resistance (R _o) can be expressed equivalently by the load. The output resistor (R _o ) and the output capacitor (C _o ) may be connected in parallel. The resonant capacitor C _p and the resonant inductor L _r may resonate with each other to transfer energy to the output terminal.

The current flow controller 130 may include a first diode D _o1 and a second diode D _o2 . The other end of the first diode set is input inductor (L _in) and a first switch (M1) the third node coupled to (n3) and a first diode (D _o1) positioned between the (D _o1) is the resonant capacitor (C _p ) and the resonant inductor (L _r ) may be connected to the fourth node (n4). One end of the second diode D _o2 is connected to the first node n1 located between the second switch M2 and the power source _{VAC , and the other end of the second diode Do2} is connected to the fourth node n4. can be connected to

The first diode D _o1 may allow a current to flow in a direction from the third node n3 to the fourth node n4 . The second diode D _o2 may allow a current to flow in a direction from the first node n1 to the fourth node n4 . The flow of the current generated in the input unit 110 for each operation mode to be described later in a predetermined direction may be controlled by the first diode D _o1 and the second diode D _{o2 .}

_{The output capacitor C o} of the power factor correction converter shown in FIG. 4 may generate a constant output voltage in a steady state. That is, the voltage difference between the ends of the _{output capacitor C o} and the voltage difference between the ends of the _{output resistor R o may be constantly maintained.} In addition, according to the power factor improving converter shown in FIG. 4 , the upper potential of the output stage may be higher than the lower potential. . The power factor correction converter may operate as a step-up converter. The step-up ratio may depend on a ratio of the first switch M1 and the second switch M2 staying in the on state within one cycle, that is, a duty cycle.

Since the resonant capacitor C _{p serves the purpose of resonance with the resonant inductor L r in} addition to the purpose of storing the energy transferred from the input inductor L _in , the charging capacity of the output capacitor C _o is determined by the resonant capacitor C _p ) can be set to be larger than the charging capacity. The first switch M1 and the second switch M2 may operate at the same time ratio. For example, the first switch M1 and the second switch M2 may repeat an on/off operation in the same cycle. Exemplarily, the first switch M1 and the second switch M2 may be in an on state together and may be in an off state together.

5 is a circuit diagram illustrating a modified example of the power factor improving converter shown in FIG. 4 . In the description of the embodiment of FIG. 5 , the contents overlapping with those of FIG. 4 will be omitted.

5, the one end of the first diode (D _o1) can be connected to a third node connected to the other terminal of the (n3) and a first diode (D _o1) is the output (C _o, R _o). In the case of FIG. 4 , when the input voltage has a positive polarity, the _{energy stored in the input inductor L in is stored in the resonance capacitor C p} when the first switch M1 and the second switch M2 are off. , when the first switch M1 and the second switch M2 are turned on, the resonant capacitor C _p and the resonant inductor L _r may be transmitted to the output terminals C _o , R _{o by resonance.} In this case, since the current _{must pass through the resonant capacitor C p} , conduction losses may be relatively large. However, as shown in FIG. 5 , when the other end of _{the first diode D o1 is connected to the output terminals C o} , R _o , when the input voltage has a positive polarity, the first switch M1 and the second switch M2 When is in the off state, the conduction loss can be relatively reduced because the _{energy stored in the input inductor L in is directly transferred to the output terminals C o} and R _o without going through the resonance capacitor C _{p .}

Hereinafter, an operation mode of the power factor improving converter according to the embodiment will be described. In the following description, the power factor improving converter shown in FIG. 4 will be mainly described, but the embodiment is not limited thereto. For example, a similar operation mode may be applied to the power factor correcting converter shown in FIG. 5 or other power factor correcting converter that can be easily changed by a person skilled in the art.

6 is a conceptual diagram illustrating an operation method of the power factor improving converter when the first switch M1 and the second switch M2 are turned on when the AC input voltage has a positive polarity. 7 is a conceptual diagram illustrating an operation method of the power factor improving converter when the first switch M1 and the second switch M2 are in an off state when the AC input voltage has a positive polarity. 8 shows the main operation waveforms of each part according to the operation of the first switch M1 and the second switch M2 when the AC input voltage has a positive polarity. The first switch M1 and the second switch M2 may repeat an on state and an off state together. In FIG. 8 , the size of the time period in the on state and the time period in the off state are the same within one period, but this is only for convenience of description, and the embodiment is not limited thereto. The size of the time period in the on state and the time period in the off state within one period may be different from each other. The duty cycle may be set differently according to the magnitude of the AC input voltage and the target step-up ratio.

6 and 8 , both the first switch M1 and the second switch M2 may maintain an ON state in the period t0 to t1. The current generated in the input unit 110 may _{pass through the power source V AC} , the input inductor L _in , the first switch M1 , and the second switch M2 . _{The current i Lin} passing through the input inductor L _in may increase during the period t0 to t1. The first switching current (i _Do1) (M1) is turned on because it is flowing through a first diode (D _o1) may be zero. Since the first switch M1 is in an on state, the voltage V _ds1 is 0V.

The current flowing through the second diode (D _o2) (i _Do2) may be zero.

Since the second switch M2 is in an on state, the voltage V _ds2 is 0V. _{A current i ds1} passing through the first switch M1 may be the same as a current i _Lin passing through the input inductor L _{in .} The voltage V _Cp of the resonant capacitor C _p may decrease during a period in which the resonant capacitor Cp and the resonant inductor Lr resonate with each other, and then become constant after the resonance is completed. The average of the _{voltage V Cp} in the entire section may be the same as the _{output voltage V o .} The output voltage _Vo may have a constant value in a steady state. Thus, the current (i _Lr) of the resonance inductor (L _r) is then the flow for the resonant capacitor (C _p) and the section in which the resonance with each other resonant inductor (L _r) is completed is the resonance is the value to be zero. _{The current i ds2} passing through the second switch M2 may be a result of subtracting _{the current i ds1} passing through the first switch M1 from the current i _Lr of the resonant inductor L _{r .}

In the period t0 to t1, the first switch M1 and the second switch M2 are turned on, energy is stored _{in the input inductor L in , and the charge charged in the resonance capacitor C p} is transferred to the resonance inductor L _r ) and energy can be transferred to the output terminals (C _o , V _{o ) by resonance.}

Referring to FIGS. 7 and 8 , both the first switch M1 and the second switch M2 may maintain an off state in the period t1 to t2 . The current generated in the input unit 110 may pass through the _{power source V AC} , the input inductor L _in , the first diode D _o1 , and the body diode D _{b2 of the second switch M2 . The current i Lin} passing through the input inductor L _in may decrease during the period t1 to t2. Since the first switch M1 is in an off state, the current i _ds1- of the first switch M1 may be zero. Accordingly, the current i _Do1 of the first diode may be equal to the current i _Lin of the input inductor L _{in . The voltage V ds1} of the first switch M1 is

It may be the same as the voltage of the resonance capacitor (C _{p ).} Since the direction of the body diode of the second switch M2 and the direction of the current i _ds2 passing through the second switch M2 are the same, the voltage V _ds2 of the second switch M2 may be zero.

The voltage (V _Cp ) of the resonant capacitor (C _p ) is after t1

The resonant inductor (Lr) current and the input inductor (Lin) current rise until they become equal to each other, and then may be stably stabilized. The current i _Lr of the resonant inductor L _r resonating with the resonant capacitor C _p may increase during a time period during which the voltage V _{Cp changes.} After changing the time interval voltage (V _Cp) current of the resonant inductor (L _r) may be equal to the current (i _Do1) of the first diode (D _{o1). The current i ds2} passing through the second switch M2 may be a result of subtracting _{the current i ds1} passing through the first switch M1 from the current i _Lr of the resonant inductor L _{r .}

In the period of time t1 to t2, the first switch M1 and the second switch M2 are turned off, and the current i _{Lin of the input inductor L in} is the first diode D _o1 and the body diode of the second switch ( D-- _b2 ) through the resonant capacitor (C _p ) can be charged. In addition, the current i _{Lin of the input inductor L in} passes through the resonance of the resonant inductor L _r and the resonant capacitor C _p , the first diode D _o1 , the resonant inductor L _r , and the third diode. It can be transmitted to the output terminals (C _o , R _o ) through (D _{A ).}

9 is a conceptual diagram illustrating an operation method of the power factor improving converter when the first switch M1 and the second switch M2 are in an on state when the AC input voltage has a negative polarity. 10 is a conceptual diagram illustrating an operation method of the power factor improving converter when the first switch M1 and the second switch M2 are in an off state when the AC input voltage has a negative polarity. 11 shows main operation waveforms of each part according to the operation of the first switch M1 and the second switch M2 when the AC input voltage has a negative polarity.

9 and 11 , both the first switch M1 and the second switch M2 may maintain an ON state in the period t0 to t1. The current generated in the input unit 110 may _{pass through the power source V AC} , the input inductor L _in , the first switch M1 , and the second switch M2 . _{The current i Lin} passing through the input inductor L _in may have a negative value and increase during the period t0 to t1. The first switching current (i _Do1) (M1) is turned on because it is flowing through a first diode (D _o1) may be zero. Since the second switch M2 is in an on state, the voltage V _ds2 of the second switch M2 may be 0V.

The current flowing through the second diode (D _o2) (i _Do2) may be zero.

Since the first switch M1 is in an on state, the voltage V _ds1 of the first switch M1 may be 0V. _{A current i ds1} passing through the first switch M1 may be the same as a current i _Lin passing through the input inductor L _{in .} Resonant capacitor voltage (V _Cp) a (C _p) is after the resonance is completed while decreasing during period in which the resonance with each other resonant capacitor (C _p) and a resonant inductor (L _r) may become the value is constant. All sectors The average of the voltage V _Cp may be equal to the _{output voltage V o .} The output voltage _Vo may have a constant value in a steady state. The resonant inductor L _r may resonate with the resonant capacitor C _p . Thus, the current (i _Lr) of the resonance inductor (L _r) is then the flow for the resonant capacitor (C _p) and the section in which the resonance with each other resonant inductor (L _r) is completed is the resonance is the value to be zero. _{The current i ds2} passing through the second switch M2 may be a result of subtracting _{the current i ds1} passing through the first switch M1 from the current i _Lr of the resonant inductor L _{r .}

In the period t0 to t1, the first switch M1 and the second switch M2 are turned on, energy is stored _{in the input inductor L in , and the charge charged in the resonance capacitor C p} is transferred to the resonance inductor L _r ) and energy can be transferred to the output terminals (C _o , V _{o ) by resonance.}

Referring to FIGS. 7 and 8 , both the first switch M1 and the second switch M2 may maintain an off state in the period t1 to t2 . Current generated in the input unit 110 can pass the power (V _AC), the second diode (D _o2), the body diode (D _b1) of a resonant capacitor (Cp), the first switch (M1). _{The current i Lin} passing through the input inductor L _in may have a negative value and decrease during the period t1 to t2. Since the second switch M2 is in an off state, the current i _ds2- of the first switch M2 may be zero. Accordingly, the current i _{Do2 of the second diode may have the same magnitude as the current i Lin} of the input inductor L _in and the sign may be opposite to that of the current i Lin . Since the direction of the body diode of the first switch M1 and the direction of the current i _ds1 passing through the first switch M1 are the same, the voltage V _ds1 of the first switch M1 may be zero. Since the second switch M2 is turned off, the voltage V _ds2 of the second switch M2 may be maintained as the voltage Vcp of the resonance capacitor Cp.

The voltage (V _Cp ) of the resonant capacitor (C _p ) rises by the current (i _Lin ) of the input inductor (L _{in ) after t1.} Since the second diode Do2 is turned on, the third diode DA is turned off by the output voltage Vo, so that the resonance inductor L _r current i _Lr may be zero. _{The current i ds2} passing through the second switch M2 may be a result of subtracting _{the current i ds1} passing through the first switch M1 from the current i _Lr of the resonant inductor L _{r .}

In the period of time t1 to t2, the first switch M1 and the second switch M2 are turned off, and the current i _{Lin of the input inductor L in} is

The resonance capacitor C _p may be charged through the body diode Db1 and the second diode D _{o2 of the first switch M1 .}

According to the above description, the electrical energy generated in the input unit 110 may be transferred to the output terminals C _o and R _{o through the resonance of the resonance capacitor C p} , the resonance inductor L _{r .} In this process, the voltage (V _{o ) of the output terminals (C o} , R _o ) may be constantly maintained without a bridge. In addition, since the power factor improving converter operates as the first switch M1 and the second switch M2 repeat on/off operations at the same time regardless of the polarity of the input voltage, the possibility of a malfunction according to the polarity of the input voltage may be reduced.

12 is a circuit diagram exemplarily showing that the Y-capacitor 140 for removing common mode noise is connected to the power factor correction converter shown in FIG. 4 .

Referring to FIG. 12 , since the voltage applied to the Y-capacitor 140 corresponds to 0 V or a low-frequency AC voltage corresponding to the input voltage (eg, an AC voltage of approximately 60 Hz), the noise characteristic is improved and the leakage current is small. can get

13 is a circuit diagram illustrating another modified example of the power factor improving converter shown in FIG. 4 .

Referring to FIG. 13 , the power factor improving converter may further include _{a fourth diode D cl .} One end of the fifth diode D _cl may be connected to the fifth node n5 and the other end may be connected to the first node n1 . The fifth node n5 may be positioned between the _{resonance inductor L r} and the third diode D _{A .} The fourth diode D _cl may allow a current in a direction from the first node n1 to the fifth node n5 . A fourth diode (D _cl) can prevent the voltage ringing (ringing) of the third diode (D _A) by the resonance of the third diode and the parasitic capacitor resonant inductor (L _r) of (D _A).

A power factor improving converter according to exemplary embodiments has been described above with reference to FIGS. 1 to 13 . According to at least one embodiment, it is possible to reduce heat generation and improve efficiency by omitting the bridge diode of the power factor improving converter. According to at least one embodiment, a low frequency voltage or a voltage having a low time change rate (dV/dt) may be applied to the Y-capacitor connected to the power factor improving converter to improve noise characteristics. According to at least one embodiment, it is possible to reduce the manufacturing cost of the power factor improving converter by simplifying the operation of switches regardless of the polarity of the AC input voltage, thereby reducing the possibility of malfunction and enabling the use of a low-cost general-purpose PFC IC instead of a microprocessor. can

As mentioned above, although the technical idea of the present invention has been described in detail with reference to preferred embodiments, the technical idea of the present invention is not limited to the above embodiments, and the technical idea of the present invention is not limited to the above embodiments. Various transformations and modifications are possible by a person having ordinary knowledge in the technical field within the scope of the idea.

Claims (1)

an input unit including an input inductor connected to a power source, and first and second switches connected to one end of the input inductor to switch a flow of current generated from the power source;
an output unit connected to the first node and the second node of the input unit and including a resonant capacitor, a resonant inductor, a third diode, and an output terminal;
and a current controller for regulating the flow of current generated from the input part, the current controller including a first diode connected to a third node of the input part and a second diode connected to the second node.

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