Apparatus for detecting current of power factor correction circuit

Abstract

Disclosed is an apparatus for detecting a current of a power factor correction circuit, the apparatus detecting a current through a current sensor provided to allow a current corresponding to a current flowing in an inductor of a boost type power factor correction circuit to flow. The apparatus for detecting a current of a power factor correction circuit comprises a slope calculation unit for calculating a first slope corresponding to a slope of a current of the inductor in a period during which a switching element of the boost type power factor correction circuit is turned on, and a second slope corresponding to a slope of a current of the inductor in a period during which the switching element is turned off, determines a detection time point of the current of the inductor in the period during which the switching element is turned off if the magnitude of the first slope is greater than the magnitude of the second slope, and determines a detection time point of the current of the inductor in the period during which the switching element is turned on if the magnitude of the first slope is less than or equal to the magnitude of the second slope.

Description

Current detection device of a power factor compensation circuit

[0001] The present invention relates to a current detection device for a power factor correction circuit, and more specifically, to a current detection device for a power factor correction (PFC) circuit capable of accurately detecting the inductor current required for current control of a power factor correction circuit.

[0002] Generally, a rectifier circuit using diodes is used to convert AC power into DC power. The output voltage of a diode rectifier circuit exhibits a pulsation with a frequency twice that of the input AC power frequency, and an electrolytic capacitor is attached to the output of the diode rectifier circuit to reduce this pulsation. In this case, current input from the AC power source to the rectifier diode can only flow when the magnitude of the AC voltage is greater than the capacitor voltage, which causes a problem of reduced power factor.

[0003] A separate circuit is used to address this power factor degradation issue, and such a circuit is called a power factor correction circuit. When constructing a power factor correction circuit using active power devices such as FETs (Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors), the control functions required for power factor compensation are implemented using analog or digital circuits. Recently, thanks to advancements in digital technology, digital PFC control circuits are widely used. To implement a high-performance digital PFC controller, accurate detection of the current supplied from the AC power source to the DC power source through the PFC circuit is required.

[0004] The matters described above as background technology are intended only to enhance understanding of the background of the present invention and should not be construed as an acknowledgment that they constitute prior art already known to those skilled in the art.

[0005] Accordingly, the present invention aims to solve the technical problem of providing a current detection device for a power factor compensation circuit capable of accurately detecting the inductor current returning for current control of the power factor compensation circuit.

[0006] The problems to be solved by the present invention are not limited to those described above, and other problems and advantages of the present invention not mentioned can be understood from the following description and will become more clearly known through the embodiments of the present invention. Furthermore, a person skilled in the art to which the present invention pertains will readily understand that the problems and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0007] As a means to solve the above technical problem, the present invention is,

[0008] A current detection device for a power factor compensation circuit comprising an inductor connected to an AC side input terminal, a diode connected to a DC side output terminal, and a switching element connected to a connection node of the inductor and the diode, wherein the current is detected through a current sensor configured to allow a current corresponding to the current flowing through the inductor of the boost-type power factor compensation circuit to flow.

[0009] A slope calculation unit that calculates a first slope corresponding to the slope of the inductor current during the ON period of the switching element and a second slope corresponding to the slope of the inductor current during the OFF period of the switching element; and

[0010] A detection time determination unit that determines the detection time of the inductor current within the interval where the switching element is off when the magnitude of the first slope is greater than the magnitude of the second slope, and determines the detection time of the inductor current within the interval where the switching element is on when the magnitude of the first slope is less than or equal to the magnitude of the second slope;

[0011] A current detection device for a power factor compensation circuit including is provided.

[0012] In an embodiment of the present invention, the slope calculation unit,

[0013] ceremony

[0014]

[0015] (L: capacitance of the above inductor, v in : The above input terminal voltage, v out : The first slope and the second slope can be calculated by the above output terminal voltage.

[0016] In an embodiment of the present invention, the detection time determination unit may determine an intermediate time point of the interval in which the switching element is off as the detection time point of the inductor current when the magnitude of the first slope is greater than the magnitude of the second slope.

[0017] In an embodiment of the present invention, the detection time determination unit may determine a control reference time corresponding to an intermediate time of the ON period of the switching element as the detection time of the current of the inductor when the magnitude of the first slope is smaller than or equal to the magnitude of the second slope.

[0018] An embodiment of the present invention may further include an inductor current conversion unit that converts the inductor detection current detected at the detection time determined by the detection time determination unit into the current at the control reference time.

[0019] In an embodiment of the present invention, the control reference point may be a point corresponding to the lowest point of a triangular wave-shaped PWM carrier signal used for the PWM of the switching element.

[0020] In an embodiment of the present invention, when the detection time determination unit determines the interval during which the switching element is off as the detection time of the inductor current, the inductor current conversion unit detects the current (i) detected at the determined detection time. L_samp Based on ), the current (i) at the above control reference point. L )cast,

[0021] ceremony

[0022]

[0023] ceremony

[0024]

[0025] (F s : Switching frequency of the switching element, duty: Duty ratio value of the switching element, T ON : It can be calculated using the predetermined turn-on delay time of the switching element.

[0026]

[0027] As another means to solve the above technical problem, the present invention is,

[0028] A current detection device of a power factor compensation circuit comprising: a first boost-type power factor compensation circuit including a first inductor connected to an AC side input terminal, a diode connected to a DC side output terminal, and a first switching element connected to a connection node of the first inductor and the diode; a second boost-type power factor compensation circuit including a second inductor connected to an AC side input terminal, a diode connected to a DC side output terminal, and a second switching element connected to a connection node of the second inductor and the diode; and a current detection device of a power factor compensation circuit configured to detect a current through a current sensor configured to allow a current corresponding to the sum of the currents flowing through the first inductor and the second inductor to flow.

[0029] A slope calculation unit that calculates a first slope corresponding to the slope of the sum of currents flowing through the first inductor and the second inductor when the first switching element is in the ON state and the second switching element is in the OFF state, and a second slope corresponding to the slope of the sum of currents flowing through the first inductor and the second inductor when the first switching element is in the OFF state and the second switching element is in the ON state; and

[0030] A detection time determination unit that determines the detection time of current within a section where the first switching element is in an off state and the second switching element is in an on state when the magnitude of the first slope is greater than the magnitude of the second slope, and determines the detection time of current within a section where the first switching element is in an on state and the second switching element is in an off state when the magnitude of the first slope is less than or equal to the magnitude of the second slope;

[0031] A current detection device for a power factor compensation circuit including is provided.

[0032] In an embodiment of the present invention, the slope calculation unit,

[0033] ceremony

[0034] : First slope

[0035] ceremony

[0036] : Second slope

[0037] (L: capacitance of the first or second inductor, v in : The above input terminal voltage, v out : The first slope and the second slope can be calculated by the above output terminal voltage.

[0038] In an embodiment of the present invention, the detection time determination unit may determine the time at which the PWM carrier signal used for the PWM of the first switching element and the PWM carrier signal used for the PWM of the second switching element have the same value as the detection time of the current when the magnitude of the first slope is greater than the magnitude of the second slope.

[0039] In an embodiment of the present invention, the detection time determination unit may determine the center point of the ON period of the first switching element as the detection time of the current when the magnitude of the first slope is smaller than or equal to the magnitude of the second slope.

[0040] An embodiment of the present invention may further include an inductor current conversion unit that converts the inductor detection current detected at the detection time determined by the detection time determination unit into the current at the control reference time.

[0041] In an embodiment of the present invention, the control reference point may be a point corresponding to the lowest point of a triangular wave-shaped PWM carrier signal used for the PWM of the first switching element.

[0042] In an embodiment of the present invention, when the detection time determination unit determines the interval in which the first switching element is in an off state and the second switching element is in an on state as the detection time of the inductor current, the inductor current conversion unit detects the current (i) detected through the current sensor at the determined detection time. Rs_samp Based on ), the current (i) at the above control reference point. L )cast,

[0043] ceremony

[0044]

[0045] ceremony

[0046]

[0047] (F s: Switching frequency of the first switching element or the second switching element, duty: duty ratio value of the first switching element or the second switching element, T ON : It can be calculated using the predetermined turn-on delay time of the first switching element or the second switching element.

[0048] According to the current detection device of the power factor compensation circuit above, the timing of detecting (sampling) the inductor current varies within a section where the slope of the current is gentle according to the current slope, and the current fed back to the current controller can be corrected using the inductor current sampled at the varied sampling time and the slope information of the inductor current.

[0049] Accordingly, according to the current detection device of the power factor compensation circuit, high-frequency pulsations included in the duty cycle used for on-off control of the switching element can be eliminated, and as a result, the control performance of the power factor compensation circuit can be significantly improved.

[0050] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below.

[0051] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to facilitate a better understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in the following drawings.

[0052] Figure 1 is a circuit diagram of a diode rectifier-based boost power factor compensation circuit.

[0053] Figure 2 is a block diagram illustrating the control circuit of the boost type power factor compensation circuit shown in Figure 1.

[0054] FIG. 3 is a waveform diagram showing the actual current flowing through the inductor when the power factor compensation circuit illustrated in FIG. 1 operates in Continuous Conduction Mode (CCM), the current sampled in a conventional manner through a shunt resistor provided to detect the inductor current, the PWM carrier signal, the PWM duty signal, and the gate signal of the switching element.

[0055] FIG. 4 is a waveform showing the half-cycle waveform of the actual current flowing through the inductor when the power factor compensation circuit illustrated in FIG. 1 operates in Continuous Conduction Mode (CCM), and the slopes of the input voltage, output voltage, and inductor current at that time.

[0056] FIGS. 5 and 6 are waveform diagrams illustrating the timing of sampling the inductor current according to the slope of the inductor current of a boost-type power factor compensation circuit in an embodiment of the present invention.

[0057] FIG. 7 is a block diagram illustrating a current detection device of a power factor compensation circuit according to an embodiment of the present invention.

[0058] FIG. 8 is a circuit diagram of a two-phase interleaved boost power factor compensation circuit to which a current detection device according to an embodiment of the present invention is applied.

[0059] Figure 9 shows the current sampling point (continuous conduction mode condition) when the slope of the current in the shunt resistor is steep in the switched-on state of the two-phase interleaved boost power factor compensation circuit shown in Figure 8.

[0060] FIGS. 10 and FIGS. 11 show the current sampling times in the continuous conduction mode and discontinuous conduction mode, respectively, when the slope of the current in the shunt resistor is gentle in the switched-on state of the two-phase interleaved boost power factor compensation circuit shown in FIG. 8.

[0061] FIG. 12 is a flowchart illustrating the operation of a current detection device of a power factor compensation circuit according to an embodiment of the present invention.

[0062] Figure 13 shows the slope waveforms of the inductor current, shunt resistor current, and shunt resistor current in the two-phase interleaved power factor compensation circuit of Figure 8.

[0063] Hereinafter, a current detection device of a power factor compensation circuit according to various embodiments of the present invention will be described in detail with reference to the attached drawings.

[0064] Specific structural or functional descriptions of the embodiments described below are disclosed merely for illustrative purposes and may be modified and implemented in various forms. Accordingly, the embodiments are not limited to specific disclosed forms, and the scope of this specification includes modifications, equivalents, or substitutions that fall within the technical concept.

[0065] Terms such as "first" or "second" may be used to describe various components, but these terms should be interpreted solely for the purpose of distinguishing one component from another. For example, the first component may be named the second component, and similarly, the second component may be named the first component.

[0066] When it is stated that a component is "connected" to another component, it should be understood that it may be directly connected to or coupled with that other component, or that there may be other components in between.

[0067] The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to specify the existence of the described features, numbers, steps, actions, components, parts, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0068] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this specification.

[0069] Figure 1 is a circuit diagram of a diode rectifier-based boost power factor compensation circuit, and Figure 2 is a block diagram of the control circuit of the circuit shown in Figure 1.

[0070] The operation of a diode rectifier-based boost power factor compensation circuit as shown in Fig. 1 can be described as follows.

[0071] AC input power (v) ac ) can be expressed as a formula as Equation 1 below.

[0072] [Equation 1]

[0073]

[0074] Here, V is the RMS value of the AC voltage, θ g is the phase angle of the AC power source, R load is the load resistance, R s represents a shunt resistor for the purpose of detecting inductor current.

[0075] In FIG. 2, the voltage controller (110) block is the output voltage (v) of the boost type power factor compensation circuit. out ) is the voltage command (v) which is the desired target value * out Current (i) flowing through the inductor (L) to reach ) L The PLL (Phase Locked Loop) (120) adjusts the peak value of the diode rectifier (11). in From the pulsation information included in ), the phase angle (θ) of the AC power source g ) calculates. The sine calculator (130) calculates the phase angle (θ) of the AC power source. g Using ) Calculate the value of, and the calculated The value of is multiplied by the output of the voltage controller (110) by the multiplier (140) to the current command (i) of the inductor (L). * L ) is derived. The current controller (150) determines the current (i) flowing through the actual inductor (L). L ) is the current command (i * L A control signal is generated to follow the (12) and transmitted to the PWM (Pulse-Width Modulation) unit (160). The PWM unit (160) controls the on-off of the switching element (Q1) of the boost power factor compensation circuit (12).

[0076] In the control of the power factor compensation circuit as described above, for the power factor compensation circuit to operate stably, the inductor current (i L Accurate detection of ) is required. Typically, inductor current (i L A shunt resistor (R) as a current sensor for detecting ) s ) or a current transformer (CT) may be used. In this specification, a shunt resistor (R s We will explain an example of applying ) as a current sensor.

[0077] FIG. 3 is a waveform diagram showing the actual current flowing through the inductor when the power factor compensation circuit illustrated in FIG. 1 operates in Continuous Conduction Mode (CCM), the current sampled in a conventional manner through a shunt resistor provided to detect the inductor current, the PWM carrier signal, the PWM duty signal, and the gate signal of the switching element. In addition, FIG. 4 is a waveform diagram showing the half-cycle waveform of the actual current flowing through the inductor when the power factor compensation circuit illustrated in FIG. 1 operates in Continuous Conduction Mode (CCM), and the slopes of the input voltage, output voltage, and inductor current at that time.

[0078] In a step-up power factor compensation circuit, the slope of the current flowing through the inductor can be given by the following Equation 2.

[0079] [Equation 2]

[0080]

[0081] In Equation 2 above, L represents the capacitance (inductance) of the inductor (L). As shown in Equation 2 and Figure 4, the slope of the inductor current is relative to the input voltage (v in ) and output voltage (v out It is affected by ). As shown in Fig. 3, the point in time at which the conventional inductor current is detected (sampled) (sampling current (i L_samp The point in time when ) is generated is the input voltage (v in ) and output voltage (v out It can be confirmed that sampling is performed in a section where the difference is not significant, and the absolute value of the current slope in the ON state of the switching element (Q1) is greater than the absolute value of the current slope in the OFF state of the switching element (Q1).

[0082] As such, conventionally, a method is generally used in power factor compensation circuits to set the sampling point of the inductor current to the interval when the switch is in the ON state. Therefore, as shown in FIG. 3, if the inductor current is sampled under conditions where the slope of the inductor current changes rapidly in the ON state, the sampling current (i L_samp The sampled current has a value that deviates irregularly from the central value of the actual inductor current, and thus contains a pulsating component. This pulsating component included in the sampled current is input to the current controller (150) and is reflected in its output, and as a result, the duty ratio of the gate signal output by the PWM unit (160) also contains a pulsating component, which causes the control performance of the power factor compensation circuit to degrade. In addition, in the conventional power factor compensation circuit, when the sampling point of the inductor current is set to the switch-on state, when the switch-on duty is small, it is very difficult to detect the current in the shunt resistor due to the ringing phenomenon.

[0083] In summary, conventional technology fixes the current sampling point to the switch-on (or off) state, resulting in cases where the inductor current is sampled under conditions where the slope of the inductor current changes abruptly. The current sampled under such conditions of abrupt slope change contains pulsations in the switching frequency band, and these pulsations in the sampled current cause a degradation in the control performance of the power factor compensation circuit.

[0084] Hereinafter, a current detection device for a power factor compensation circuit according to an embodiment of the present invention is described in detail to improve the above-mentioned problem caused by fixing the sampling point of the inductor current in the power factor compensation circuit to the switch-on state (or off state).

[0085] An embodiment of the present invention provides a current detection device for a power factor compensation circuit that varies the inductor current sampling time of the power factor compensation circuit according to the current slope, and corrects the current fed back to the current controller using the inductor current sampled at the time of variation and the slope information of the inductor current.

[0086] First, to explain the operating principle of the inductor current detection device of the power factor compensation circuit according to an embodiment of the present invention, a technique for determining the detection time (sampling time) based on the waveform of the inductor current of the boost-type power factor compensation circuit is described.

[0087] FIGS. 5 and 6 are waveform diagrams illustrating the timing of sampling the inductor current according to the slope of the inductor current of a boost-type power factor compensation circuit in an embodiment of the present invention.

[0088] As shown in the aforementioned Equation 2 and FIG. 3, the slope of the inductor current according to the on-off state of the switching element (Q1) is the input voltage (v) of the power factor compensation circuit (12). in ) and output voltage (v out It is affected by ). In an embodiment of the present invention, the central point of the ON state of the switching element (Q1) (a point corresponding to the lowest point of the triangular wave-shaped PWM carrier signal used in the PWM unit (160)) is set as the reference point (C) for current control, and an inductor current detection technique according to an embodiment of the present invention is described.

[0089] In an embodiment of the present invention, a current controller (15) can operate using the current detected at the center point of the ON state of the switching element (Q1). As shown in FIG. 5, the inductor current (i) at the reference point of the current control LIf the slope of ) is steeper than the inductor current slope at the center point of the off state of the switching element (Q1) ((a point corresponding to the peak of the triangular wave-shaped PWM carrier signal used in the PWM section (160))), the center point of the off state of the switching element (Q1) is set as the current sampling point (S), and the current (i) sampled at the set current sampling point (S) L_samp Current (i) at the current control reference point based on ) L ) is obtained as shown in the following Equations 3 and 4 to obtain the current controller (i L It can be used as input for ).

[0090] [Equation 3]

[0091]

[0092] [Equation 4]

[0093]

[0094] Here, F s is the switching frequency of the switching element (Q1) of the power factor compensation circuit, and duty represents the duty ratio value determined one cycle prior to the current control reference point in the PWM section (160). T ON represents the turn-on delay time of the switching element (Q1) of the power factor compensation circuit.

[0095] As shown in Fig. 6, when the slope of the inductor current at the reference point (C) of the current control is gentler than the slope of the inductor current at the center point of the off state of the switching element (Q1), the current sampled at the reference point (C) of the current control is used as the input to the current controller (150).

[0096] As such, the current detection technique of the power factor compensation circuit applied in the embodiment of the present invention can resolve the problem caused by detecting the current in a section where the inductor current changes rapidly by detecting (sampling) the current in a section where the magnitude (absolute value) of the slope (rate of change) of the inductor current is not large.

[0097] FIG. 7 is a block diagram illustrating a current detection device of a power factor compensation circuit according to an embodiment of the present invention.

[0098] Referring to FIG. 7, a current detection device (20) of a power factor compensation circuit according to an embodiment of the present invention for implementing the inductor current detection technique as described above is, in the period when the switching element (Q1) of the boost-type power factor compensation circuit (12) is ON, the inductor current (i L The slope of ) The inductor current (i) in the interval where the switching element (Q1) is off and the first slope corresponding to ) L The slope of ) It may include a slope calculation unit (21) that calculates a second slope corresponding to ), and a detection time determination unit (22) that determines the detection time of the inductor current within the interval where the switching element (Q1) is off when the magnitude of the first slope calculated by the slope calculation unit (21) is greater than the magnitude of the second slope, and determines the detection time of the inductor current within the interval where the switching element (Q1) is on when the magnitude of the first slope calculated by the slope calculation unit (21) is less than or equal to the magnitude of the second slope.

[0099] In addition, the current detection device of the power factor compensation circuit according to an embodiment of the present invention may further include an inductor current conversion unit (23) that converts the inductor detection current detected at a determined detection time into a current at a control reference time.

[0100] The current detection device (20) of the power factor compensation circuit is implemented by a controller including a processor and a memory including an operation algorithm performed in the processor, and each component of the current detection device (20) of the power factor compensation circuit may correspond to a respective functional module that performs a specific operation or command.

[0101] The slope calculation unit (21) can calculate the slope of the inductor current through the aforementioned Equation 2. The input voltage (v) of the power factor compensation circuit (12) in ) and output voltage (v out ) can be measured by a conventional voltage sensor (not shown) provided at the input and output terminals of the power factor compensation circuit (12). The slope calculation unit (21) applies Equation 2 to the inductor current (i) during the period when the switching element (Q1) is ON. L The slope of ) The inductor current (i) in the interval where the switching element (Q1) is off and the first slope corresponding to ) L The slope of ) The second slope corresponding to ) can be calculated.

[0102] The ON period and OFF period of the switching element can be obtained from the PWM unit (160) in the control circuit of the power factor compensation circuit shown in FIG. 2. As shown in FIGS. 3 to 5, the PWM unit (160) is a component that generates a gate signal of the switching element (Q1) by comparing a PWM carrier signal in the form of a triangular wave having a predetermined frequency with a PWM duty signal of a constant magnitude whose magnitude is determined by the control signal of the current controller (150). For example, the PWM unit (160) can turn on the switching element (Q1) by outputting a high-level gate signal in a period where the PWM carrier signal is smaller than the PWM duty signal, and turn off the switching element (Q1) by outputting a low-level gate signal in a period where the PWM carrier signal is larger than the PWM duty signal. Therefore, the ON / OFF state of the switching element (Q1) can be checked through the gate signal output from the PWM unit (160).

[0103] The detection time determination unit (22) can determine the detection time of the inductor current within the interval where the switching element (Q1) is off when the magnitude of the first slope calculated by the slope calculation unit (21) as shown in FIG. 5 is greater than the magnitude of the second slope, and can determine the detection time of the inductor current within the interval where the switching element (Q1) is on when the magnitude of the first slope calculated by the slope calculation unit (21) as shown in FIG. 6 is smaller than the magnitude of the second slope. Of course, when the magnitude of the first slope and the magnitude of the second slope are the same, it is preferable to determine the detection time of the inductor current within the interval where the switching element (Q1) is on, which is capable of detection at the same time as the control reference time (C).

[0104] After the detection (sampling) of the current is completed, if the sampling time and the control reference time are different, the sampled inductor current and the inductor current used for control are different, so it is necessary to convert the sampled inductor current as shown in Equations 3 and 4. To this end, the current detection device (20) of the power factor compensation circuit according to an embodiment of the present invention may further include an inductor current conversion unit (23) that converts the inductor detection current detected at a determined detection time into the current at the control reference time.

[0105] The switching frequency (F) of the switching element (Q1) of the power factor compensation circuit used in the calculation of the inductor current conversion unit (23) s ) can be pre-set, and the duty ratio value can be derived through a gate signal determined in the PWM unit (160), and the turn-on delay time (T) of the switching element (Q1) of the power factor compensation circuit ON ) may be a value determined in advance as an intrinsic characteristic of the switching element (Q1).

[0106] After the detection (sampling) of the current is completed, if the sampling time and the control reference time are the same (if the magnitude of the first slope calculated by the slope calculation unit (21) is smaller than the magnitude of the second slope), the sampled inductor current can be determined as the inductor current input to the current controller (150).

[0107] Current sampling is performed at a determined sampling point using a shunt resistor (R s Detects the voltage across the terminals of ), and the detected voltage value and the predetermined shunt resistor (R s This can be performed by a detection current calculation unit (24) that detects the magnitude of the current by applying Ohm's law to the resistance value of the current. Since the current detection calculation of the detection current calculation unit (24) corresponds to a self-evident known technology in the field of technology, further detailed explanation will be omitted.

[0108] FIG. 8 is a circuit diagram of a two-phase interleaved boost power factor compensation circuit to which a current detection device according to an embodiment of the present invention is applied.

[0109] As shown in FIG. 8, the interleaved boost power factor compensation circuit has a structure in which two boost power factor compensation circuits (14a, 14b) are connected in parallel between the input and output terminals, and the first switching element (Q1) and the second switching element (Q2) included in each boost power factor compensation circuit (14a, 14b) can be controlled by gate signals having the same frequency and a phase difference of 180 degrees from each other.

[0110] In FIG. 8, the first inductor current ( iL1 ) is controlled, and the second inductor current ( iL2 ) is controlled. In the two-phase interleaved boost power factor compensation circuit of Fig. 8, the shunt resistor (R sThe first inductor current ( iL1 ) and second inductor current( iL2 Detects the current that is the sum of ), and from this, the first inductor current ( iL1 ) and second inductor current( iL2 The average current of ) can be calculated. In FIG. 8, the auxiliary shunt resistor (R) connected to each switching element of each power factor compensation circuit. Q1 ) and auxiliary shunt resistor (R Q2 ) is the first inductor current ( iL1 ) and second inductor current( iL2 Imbalance between ) (first inductor current ( iL1 ) and second inductor current( iL2 It can be used to detect the magnitude of each current and compensate for the imbalance when a situation occurs where the average current magnitude of ) differs.

[0111] FIG. 9 shows the shunt resistor (R) in the switched-on state of the two-phase interleaved boost power factor compensation circuit illustrated in FIG. 8. s ) current(i Rs A steep slope indicates the current sampling point (continuous conduction mode condition).

[0112] In FIG. 9, the period during which the first switching element (Q1) is turned on is very short, and during that period, the shunt resistor (R s The slope of the current flowing through ) is steep. Therefore, due to the ringing phenomenon and the influence of the steep slope, the shunt resistance (R s It is very difficult to detect the current through ). In such a case, as shown in FIG. 9, at the point in time when both the first switching element (Q1) and the second switching element (Q2) remain in the off state (corresponding to the point in time in FIG. 9 when the PWM carrier signals of the first switching element (Q1) and the second switching element (Q2) have the same value), the shunt resistor (R s Sampling the current through ) to obtain the sampled current value (i Rs_samp Generates ) and detected sampling current value (i Rs_sampThe current (i) input to the current controller at the control reference point (indicated as C) from ) and the PWM duty cycle L ) can be predicted as shown in the following Equations 5 and 6. Here, the control reference point (C) can be the point in time corresponding to the lowest point of the triangular wave-shaped PWM carrier signal used for the PWM of the first switching element (Q1).

[0113] [Equation 5]

[0114]

[0115] [Equation 6]

[0116]

[0117] FIGS. 10 and 11 show the shunt resistor (R) in the switched-on state of the two-phase interleaved boost power factor compensation circuit illustrated in FIG. 8. s ) current(i Rs When the slope of ) is gentle, it represents the current sampling time in continuous conduction mode and discontinuous conduction mode, respectively.

[0118] As shown in FIGS. 10 and 11, in the switched-on state, the shunt resistor (R s ) current(i Rs When the slope of ) is gentle, the current sampled from the current control reference point is used as the input to the current controller.

[0119] FIG. 12 is a flowchart illustrating the operation of a current detection device of a power factor compensation circuit according to an embodiment of the present invention.

[0120] First, the slope calculation unit (21) calculates the inductor current (i) during the period when the switching element (Q1) of the boost power factor compensation circuit (12) is on. L The slope of ) The inductor current (i) in the interval where the switching element (Q1) is off and the first slope corresponding to ) L The slope of ) A second slope corresponding to ) can be calculated (S11).

[0121] When applying a single power factor compensation circuit as shown in FIG. 1, the slope calculation unit (21) uses Equation 2 to calculate the slope (in the period when the switching element (Q1) is ON) ) and the slope in the interval when the switching element (Q1) is off ( ) can be operated on.

[0122] In the case of a two-phase interleaved PFC circuit as shown in Fig. 8, the slope ( ) and slope( ) is a shunt resistor (R) that detects the sum of inductor currents according to the switching state of the first switching element (Q1) and the second switching element (Q2). s It refers to the slope of the current flowing through ).

[0123] The slope of the current flowing through the shunt resistor (Rs) when the first switching element (Q1) is in the ON state and the second switching element (Q2) is in the OFF state ( ) can be obtained as shown in Equation 7 below, and the slope of the current flowing through the shunt resistor (Rs) when the first switching element (Q1) is in the off state and the second switching element (Q2) is in the on state ( ) can be calculated as shown in the following Equation 8.

[0124] [Equation 7]

[0125]

[0126] [Equation 8]

[0127]

[0128] Next, the detection time determination unit (22) can compare the magnitudes of the first slope and the second slope calculated by the slope calculation unit (S12) and determine the sampling time according to the result (S131, S132).

[0129] When using the single power factor compensation circuit of FIG. 1, the first sampling point corresponds to the center point of the off period of the switching element (Q1), and the second sampling point corresponds to the center point of the on period of the switching element (Q1). Here, class Based on the size comparison result, the first sampling point is This applies to the case of, and the second sampling point is This applies to the case of.

[0130] When the sampling is completed using the first sampling time (S141), the inductor current conversion unit (23) can provide the inductor current calculated by Equations 3 and 4 to the current controller (150) to enable the control of the switching element (S151). When the sampling is completed using the second sampling time (S142), the sampled current can be provided as is to the current controller (150) to enable the control of the switching element (S152).

[0131] The detection current calculation unit (24) determines the shunt resistor (R) at the determined sampling time. s Detects the voltage across the terminals of ), and the detected voltage value and the predetermined shunt resistor (R s The magnitude of the current can be detected by applying Ohm's law to the resistance value of ).

[0132] When using the two-phase interleaved power factor compensation circuit illustrated in FIG. 8, the first sampling point may correspond to the point in time (indicated as S in FIG. 7) when the triangular wave signal (carrier signal) used for the PWM of the first switching element (Q1) and the triangular wave signal (carrier signal) used for the PWM of the second switching element (Q2) have the same value. Additionally, the second sampling point corresponds to the center point of the ON period of the first switching element (Q1) (indicated as S in FIG. 8 and 9). When using the two-phase interleaved power factor compensation circuit, using the slope based on Equations 7 and 8, On the other hand, current control can be performed by providing the current calculated by Equations 5 and 6 based on the current detected at the first sampling point to the current controller (150). Additionally, when using a two-phase interleaved power factor compensation circuit, using the slope based on Equations 7 and 8, Then, the current detected at the second sampling point can be provided as is to the current controller (150) to enable current control.

[0133] FIG. 13 shows the slope waveforms of the inductor current, shunt resistor current, and shunt resistor current in the two-phase interleaved power factor compensation circuit of FIG. 8. As previously mentioned, class The current sampling time is changed according to the result of the size comparison, and the value of the current used provided to the current controller (150) is determined.

[0134] As described above, the current detection device of the power factor compensation circuit according to the embodiment of the present invention can change the timing of detecting (sampling) the inductor current within a section where the slope of the current is gentle according to the current slope, and can correct the current fed back to the current controller using the inductor current sampled at the changed sampling time and the slope information of the inductor current. Accordingly, the current detection device of the power factor compensation circuit according to the embodiment of the present invention can eliminate high-frequency pulsations included in the duty cycle used for on-off control of the switching element, and as a result, can significantly improve the control performance of the power factor compensation circuit.

[0135] [Explanation of Drawing Symbols]

[0136] 11: Diode rectifier 12, 12a, 12b: Boost power factor correction circuit

[0137] 110: Voltage Controller 120: PLL

[0138] 130: Sine operator 140: Multiplier

[0139] 150: Current controller 160: PWM section

[0140] 20: Current detection device 21: Slope calculation unit

[0141] 22: Detection time determination unit 23: Inductor current conversion unit

[0142] 24: Detected Current Calculation Unit

Claims

A current detection device for a power factor compensation circuit comprising an inductor connected to an AC side input terminal, a diode connected to a DC side output terminal, and a switching element connected to a connection node of the inductor and the diode, wherein the current is detected through a current sensor configured to allow a current corresponding to the current flowing through the inductor of the boost-type power factor compensation circuit to flow. A slope calculation unit that calculates a first slope corresponding to the slope of the inductor current during the ON period of the switching element and a second slope corresponding to the slope of the inductor current during the OFF period of the switching element; and A detection time determination unit that determines the detection time of the inductor current within the interval where the switching element is off when the magnitude of the first slope is greater than the magnitude of the second slope, and determines the detection time of the inductor current within the interval where the switching element is on when the magnitude of the first slope is less than or equal to the magnitude of the second slope; A current detection device for a power factor compensation circuit including In claim 1, the slope calculation unit, ceremony (L: capacitance of the above inductor, v in : The above input terminal voltage, v out A current detection device for a power factor compensation circuit characterized by calculating the first slope and the second slope based on the output terminal voltage. In claim 1, the detection time determination unit is, A current detection device for a power factor compensation circuit, characterized in that when the magnitude of the first slope is greater than the magnitude of the second slope, the intermediate point of the interval in which the switching element is off is determined as the detection point of the current of the inductor. In claim 1, the detection time determination unit is, A current detection device for a power factor compensation circuit, characterized in that when the magnitude of the first slope is smaller than or equal to the magnitude of the second slope, a control reference point corresponding to the middle point of the switching element's ON period is determined as the detection point of the inductor's current. In claim 1, A current detection device of a power factor compensation circuit further comprising an inductor current conversion unit that converts the inductor detection current detected at the detection time determined by the detection time determination unit into the current of the control reference time. In claim 5, the control reference point is, A current detection device for a power factor compensation circuit characterized by being at a point in time corresponding to the lowest point of a triangular wave-shaped PWM carrier signal used for the PWM of the switching element. In claim 5, If the detection time determination unit determines the interval during which the switching element is off as the detection time of the inductor current, The above inductor current converter is the current (i) detected at a determined detection point. L_samp Based on ), the current (i) at the above control reference point. L )cast, ceremony ceremony (F s : Switching frequency of the switching element, duty: Duty ratio value of the switching element, T ON : The predetermined turn-on delay time of the switching element) A current detection device for a power factor compensation circuit characterized by performing calculations using A current detection device of a power factor compensation circuit comprising: a first boost-type power factor compensation circuit including a first inductor connected to an AC side input terminal, a diode connected to a DC side output terminal, and a first switching element connected to a connection node of the first inductor and the diode; a second boost-type power factor compensation circuit including a second inductor connected to an AC side input terminal, a diode connected to a DC side output terminal, and a second switching element connected to a connection node of the second inductor and the diode; and a current detection device of a power factor compensation circuit configured to detect a current through a current sensor configured to allow a current corresponding to the sum of the currents flowing through the first inductor and the second inductor to flow. A slope calculation unit that calculates a first slope corresponding to the slope of the sum of currents flowing through the first inductor and the second inductor when the first switching element is in the ON state and the second switching element is in the OFF state, and a second slope corresponding to the slope of the sum of currents flowing through the first inductor and the second inductor when the first switching element is in the OFF state and the second switching element is in the ON state; and A detection time determination unit that determines the detection time of current within a section where the first switching element is in an off state and the second switching element is in an on state when the magnitude of the first slope is greater than the magnitude of the second slope, and determines the detection time of current within a section where the first switching element is in an on state and the second switching element is in an off state when the magnitude of the first slope is less than or equal to the magnitude of the second slope; A current detection device for a power factor compensation circuit including In claim 8, the slope calculation unit, ceremony : First slope ceremony : Second slope (L: capacitance of the first or second inductor, v in : The above input terminal voltage, v out A current detection device for a power factor compensation circuit characterized by calculating the first slope and the second slope based on the output terminal voltage. In claim 8, the detection time determination unit is, A current detection device for a power factor compensation circuit, characterized in that when the magnitude of the first slope is greater than the magnitude of the second slope, the point in time when the PWM carrier signal used for the PWM of the first switching element and the PWM carrier signal used for the PWM of the second switching element have the same value is determined as the current detection point. In claim 8, the detection time determination unit is, A current detection device for a power factor compensation circuit, characterized in that when the magnitude of the first slope is smaller than or equal to the magnitude of the second slope, the center point of the ON period of the first switching element is determined as the current detection point. In claim 8, A current detection device of a power factor compensation circuit further comprising an inductor current conversion unit that converts the inductor detection current detected at the detection time determined by the detection time determination unit into the current of the control reference time. In claim 12, the control reference point is, A current detection device for a power factor compensation circuit characterized by being at a point in time corresponding to the lowest point of a triangular wave-shaped PWM carrier signal used for the PWM of the first switching element. In claim 13, When the detection time determination unit determines the interval in which the first switching element is in the off state and the second switching element is in the on state as the detection time of the inductor current, The above inductor current converter is the current (i) detected through the current sensor at a determined detection time. Rs_samp Based on ), the current (i) at the above control reference point. L )cast, ceremony ceremony (F s : Switching frequency of the first switching element or the second switching element, duty: duty ratio value of the first switching element or the second switching element, T ON A current detection device for a power factor compensation circuit characterized by performing calculations using a predetermined turn-on delay time of the first switching element or the second switching element.

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