WO2019131469A1 - Power supply device and power supply device control method - Google Patents

Power supply device and power supply device control method Download PDF

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Publication number
WO2019131469A1
WO2019131469A1 PCT/JP2018/047132 JP2018047132W WO2019131469A1 WO 2019131469 A1 WO2019131469 A1 WO 2019131469A1 JP 2018047132 W JP2018047132 W JP 2018047132W WO 2019131469 A1 WO2019131469 A1 WO 2019131469A1
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Prior art keywords
switching element
current
transformer
time
power supply
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PCT/JP2018/047132
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French (fr)
Japanese (ja)
Inventor
隆章 佐野
魁元 張
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住友電気工業株式会社
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Publication of WO2019131469A1 publication Critical patent/WO2019131469A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac

Definitions

  • the present disclosure relates to a power supply device and a control method of the power supply device.
  • This application claims priority based on Japanese Patent Application No. 2017-249909 filed on Dec. 26, 2017, and incorporates all the contents described in the aforementioned Japanese application.
  • a DC / DC converter that converts a DC voltage is used in industrial equipment and in-vehicle devices.
  • the DC / DC converter includes an active clamp type DC / DC converter.
  • an active clamp type DC / DC converter a series circuit of a primary winding of a transformer and a main switching element is connected to a DC power supply, and an active clamp circuit consisting of a capacitor and an auxiliary switching element is connected across the primary winding. ing. Then, by alternately turning on / off the main switching element and the auxiliary switching element at a required duty ratio, magnetization energy and leakage energy of the transformer are circulated through the capacitor of the active clamp circuit to improve the power supply conversion efficiency. be able to.
  • Patent Document 1 the instantaneous value of the primary side current of the transformer is detected, and the difference between the detected instantaneous value and the average value of the instantaneous values in the past is determined. If the difference is equal to or more than a predetermined value, the excitation operation of the transformer Discloses a DC / DC converter that performs a magnetic reset by stopping the
  • a power supply device includes a transformer, a first switching element connected in series to a primary winding of the transformer, and a first capacitor connected in parallel to the first switching element. And a series circuit of a second switching element and a second capacitor connected in parallel to the primary winding, and turning on / off the first switching element and the second switching element in a predetermined switching cycle.
  • a power supply device includes a transformer, a first switching element connected in series to a primary winding of the transformer, and a second switching element connected in parallel to the primary winding.
  • a control unit configured to turn on / off the first switching element and the second switching element in a predetermined switching cycle, the current acquisition unit acquiring the current of the transformer, and Whether or not the transformer reaches magnetic saturation based on the current acquired by the current acquisition unit when a predetermined time has elapsed from the time when the switching element is turned on or when the second switching element is turned off
  • An estimation unit is provided, and the control unit controls the on / off operation of the second switching element based on the estimation result of the estimation unit.
  • a transformer In a control method of a power supply device according to an embodiment of the present disclosure, a transformer, a first switching element connected in series to a primary winding of the transformer, and a second switching element connected in parallel to the first switching element , A series circuit of a second switching element and a second capacitor connected in parallel to the primary winding, and the first switching element and the second switching element on / off in a predetermined switching cycle.
  • a control method of a power supply device comprising: a control unit configured to perform an off operation, wherein a current of the transformer is acquired, the first switching element is in an off state, and the second switching element is turned on or Based on the acquired current, it is estimated whether or not the transformer reaches magnetic saturation when a predetermined time has elapsed since the second switching element is turned off. , The control unit controls the on / off operation of the first switching element or the second switching element based on the estimation result.
  • a transformer In a control method of a power supply device according to an embodiment of the present disclosure, a transformer, a first switching element connected in series to a primary winding of the transformer, and a second switch connected in parallel to the primary winding.
  • a control method of a power supply device comprising: a switching element; and a control unit for turning on / off the first switching element and the second switching element in a predetermined switching cycle, obtaining a current of the transformer, Whether or not the transformer reaches magnetic saturation is estimated based on the acquired current when a predetermined time elapses from the on time of the second switching element or the off time of the second switching element, The control unit controls the on / off operation of the second switching element based on the estimation result.
  • magnetic saturation of the transformer can be prevented in advance.
  • the power supply device includes a transformer, a first switching element connected in series to a primary winding of the transformer, and a first capacitor connected in parallel to the first switching element.
  • a control circuit that turns on / off the first switching element and the second switching element in a predetermined switching cycle, and a series circuit of a second switching element and a second capacitor connected in parallel to the primary winding.
  • a current acquisition unit for acquiring the current of the transformer, and the first switching element is in the OFF state, and the second switching element is turned on or when the second switching element is turned on.
  • Whether or not the transformer reaches magnetic saturation is estimated based on the current acquired by the current acquisition unit when a predetermined time has elapsed since the switching element was turned off.
  • a estimation unit wherein the control unit controls the on / off operation of the first switching element or the second switching element based on an estimation result of the estimation unit.
  • a control method of a power supply device includes a transformer, a first switching element connected in series to a primary winding of the transformer, and a first switching element connected in parallel to the first switching element. ON / OFF operation of a capacitor, a series circuit of a second switching element and a second capacitor connected in parallel to the primary winding, and the first switching element and the second switching element in a predetermined switching cycle And a control unit for controlling the power supply device, wherein the current of the transformer is acquired, the first switching element is in the off state, and the second switching element is turned on or when the first switching element is turned on.
  • the control unit controls the on / off operation of the first switching element or the second switching element based on the estimation result.
  • the current acquisition unit acquires the current of the transformer.
  • the estimation unit estimates whether or not the transformer reaches magnetic saturation based on the current acquired when the first switching element is in the off state and the second switching element is on. Further, the estimation unit determines whether or not the transformer is magnetically saturated based on the current acquired when the first switching element is in the off state and a predetermined time has elapsed from the time when the second switching element is off. To estimate.
  • the assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached.
  • period D1 When the first switching element is in the on state and the second switching element is in the off state (referred to as period D1), a voltage on the input side is applied to the primary winding of the transformer, and the primary winding of the transformer is The sum of the load current and the excitation current flows.
  • period D2 When the first switching element is turned off and both the first switching element and the second switching element are turned off (referred to as period D2), the excitation current is maintained at a constant value but the load current is decreased.
  • the load current flowing through the primary winding of the transformer is 0 and only the excitation current become. Therefore, the first switching element is in the off state, and the current acquired at the on time of the second switching element is only the excitation current, and the influence of the load current is excluded to accurately determine the possibility of magnetic saturation of the transformer. Can be estimated.
  • period D4 When the second switching element is turned off and both the first switching element and the second switching element are turned off (referred to as period D4), resonance occurs due to the leakage inductance of the transformer and the capacitance of the first capacitor. Resonant current flows in the primary winding of the transformer. When the magnetic flux balance is broken as a sign of reaching magnetic saturation, the amplitude of the resonant current increases, so that the first switching element is in the OFF state, and a predetermined time has elapsed from the time when the second switching element is off (for example, The possibility of magnetic saturation of the transformer can be accurately estimated on the basis of the current obtained at the required point in resonance (ie the resonant current).
  • the resonance current resonates on both the positive side and the negative side with current 0 in between, if the amplitude on the positive side of the resonance current is detected, the amplitude on the negative side of the resonance current can be estimated. Therefore, even if a current sensor capable of detecting only the positive polarity is used, magnetic saturation due to the negative excitation current when resetting the transformer excitation can be estimated.
  • the control unit controls the on / off operation of the first switching element or the second switching element based on the estimation result of the estimation unit.
  • the on / off operation of the first switching element or the second switching element can be controlled before magnetic saturation occurs. Thereby, magnetic saturation of the transformer can be prevented in advance.
  • the estimation unit causes the transformer to be magnetically saturated based on the current acquired by the current acquisition unit at the time when the second switching element is turned on and the first threshold. It is presumed that the control unit stops the on / off operation of the first switching element and the second switching element.
  • the estimation unit estimates that the transformer reaches magnetic saturation based on the acquired current and the first threshold when the second switching element is turned on.
  • the control unit stops the on / off operation of the first switching element and the second switching element. If there is a high possibility of magnetic saturation and the switching operation is continued even if the duty ratio (on period) of the first switching element is adjusted, the switching operation is stopped if it is estimated that the magnetic saturation will occur. Do. Thereby, it is possible to prevent in advance the magnetic saturation due to the positive side excitation current when exciting the transformer.
  • the estimation unit is based on the first current acquired by the current acquisition unit at the on time of the second switching element in one switching cycle, and the first threshold.
  • the estimation unit is based on the acquired first current and the first threshold at the on time point of the second switching element in one switching cycle, and the first current of the one switching cycle and the one switching Based on the ratio to the second current acquired at the on time of the second switching element in the switching cycle earlier than the cycle, and the second threshold, it is estimated that the transformer will reach magnetic saturation.
  • the control unit controls the on / off operation such that the on period of the first switching element becomes short.
  • the current of the primary winding of the transformer that is, the excitation current of the transformer
  • the duty ratio (on period) of the first switching element is adjusted If it is possible to avoid the magnetic saturation state, the on / off operation is controlled so that the on period of the first switching element becomes short without stopping the switching operation. Thereby, magnetic saturation can be prevented in advance.
  • the estimation unit is based on the current acquired by the current acquisition unit at the time when the predetermined time has elapsed from the time when the second switching element is turned off and the third threshold. It is estimated that the transformer has reached magnetic saturation, and the control unit stops the on / off operation of the first switching element and the second switching element.
  • the estimation unit estimates that the transformer reaches magnetic saturation based on the current acquired when a predetermined time has elapsed from the off time of the second switching element and the third threshold.
  • the control unit stops the on / off operation of the first switching element and the second switching element. If there is a high possibility of magnetic saturation and switching operation is continued even if the duty ratio (on period) of the second switching element is adjusted, the switching operation is stopped if it is estimated that the magnetic saturation will occur. Do. As a result, even in the case of a current sensor capable of detecting only the positive polarity, it is possible to prevent in advance the magnetic saturation due to the negative excitation current in the case of resetting the excitation of the transformer.
  • the estimation unit is configured to receive the first current acquired by the current acquisition unit when the predetermined time has elapsed from the time when the second switching element is turned off in one switching cycle. And the third current threshold, and the current acquisition unit at the time when the predetermined time has elapsed from the time when the second switching element is turned off in a switching cycle earlier than the first current and the one switching cycle.
  • the transformer is estimated to reach magnetic saturation, and the control unit turns on so that the on period of the second switching element becomes short. Control / off operation.
  • the estimation unit is based on the first current and the third threshold acquired when a predetermined time has elapsed from the off time point of the second switching element in one switching cycle, and the first in the one switching cycle Based on a fourth threshold and a ratio of a current to a second current obtained when a predetermined time has elapsed from the time when the second switching element is turned off in a switching cycle earlier than the one switching cycle, and It is estimated that the transformer leads to magnetic saturation.
  • the control unit controls the on / off operation such that the on period of the second switching element becomes short.
  • the current that is, the resonant current
  • the duty ratio on period of the second switching element
  • the predetermined time includes a time of 1 ⁇ 4 of a resonance period relying on the leakage inductance of the transformer and the capacitance of the first capacitor and a time near the time.
  • the predetermined time includes a time of 1 ⁇ 4 of the resonance period Td relying on the leakage inductance of the transformer and the capacitance of the first capacitor and a time close to the time. Since the resonant current is sinusoidal, the time from the peak of the negative amplitude of the resonant current to the peak of the positive amplitude corresponds to a quarter of the resonance period Td. Also, the peak of the negative amplitude of the resonant current is considered to be equal to the peak of the positive amplitude. Therefore, the peak value of the negative amplitude can be estimated by detecting the current at Td / 4 from the peak of the negative amplitude of the resonant current.
  • the point at which the amplitude on the negative side of the resonance current peaks is at the point when the first switching element is in the off state and the second switching element is off.
  • the near time may be, for example, a time in which the variation of the resonance period is considered in consideration of the variation of the leakage inductance of the transformer and the capacitance of the first capacitor.
  • a current sensor capable of detecting only the positive polarity it is possible to prevent in advance the magnetic saturation due to the negative excitation current in the case of resetting the excitation of the transformer.
  • a current sensor capable of detecting a negative current needs to include a circuit for converting the current to a positive polarity, an amplification circuit, and the like, which is generally expensive. Since a current sensor capable of detecting only positive polarity can be used, it contributes to cost reduction.
  • a power supply device includes: a transformer; a first switching element connected in series to a primary winding of the transformer; a second switching element connected in parallel to the primary winding;
  • a power supply device comprising: a control unit that turns on / off a first switching element and a second switching element in a predetermined switching cycle, and a current acquisition unit that acquires a current of the transformer; and the second switching An estimation unit that estimates whether or not the transformer reaches magnetic saturation based on the current acquired by the current acquisition unit when a predetermined time has elapsed from the time when the element is turned on or when the second switching element is turned off And the control unit controls the on / off operation of the second switching element based on the estimation result of the estimation unit.
  • a control method of a power supply device includes a transformer, a first switching element connected in series to a primary winding of the transformer, and a second switching element connected in parallel to the primary winding. And a control unit configured to turn on / off the first switching element and the second switching element in a predetermined switching cycle, and obtaining a current of the transformer, At the time when a predetermined time has elapsed from the time when the switching element is turned on or the time when the second switching element is turned off, it is estimated whether or not the transformer reaches magnetic saturation based on the acquired current, and the control The unit controls the on / off operation of the second switching element based on the estimation result.
  • the current acquisition unit acquires the current of the transformer.
  • the estimation unit estimates whether or not the transformer reaches magnetic saturation based on the current acquired at the on time of the second switching element. Further, the estimation unit estimates whether or not the transformer reaches magnetic saturation based on the current acquired when a predetermined time has elapsed from the time when the second switching element is turned off.
  • the assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached.
  • a voltage on the input side is applied to the primary winding of the transformer, and a total of load current and excitation current flows through the primary winding of the transformer.
  • period D2 When the first switching element is turned off and both the first switching element and the second switching element are turned off (referred to as period D2), the excitation current is maintained at a constant value but the load current is decreased.
  • the load current flowing through the primary winding of the transformer becomes 0 and becomes only the excitation current. Therefore, the current acquired at the on time of the second switching element is only the excitation current, and the influence of the load current can be excluded to accurately estimate the possibility of magnetic saturation of the transformer.
  • period D4 When the second switching element is turned off and both the first switching element and the second switching element are turned off (referred to as period D4), the leakage inductance of the transformer and the capacitors (floating on both ends of the first switching element) The resonance (which also includes the capacitance) occurs, and a resonant current flows in the primary winding of the transformer. Since the amplitude of the resonant current increases when the magnetic flux balance breaks down as a sign of reaching magnetic saturation, the current acquired when a predetermined time has elapsed from the time when the second switching element is off (for example, the required time during resonance) Based on (i.e., the resonant current), the possibility of magnetic saturation of the transformer can be accurately estimated.
  • the resonance current resonates on both the positive side and the negative side with current 0 in between, if the amplitude on the positive side of the resonance current is detected, the amplitude on the negative side of the resonance current can be estimated. Therefore, magnetic saturation due to the excitation current on the negative side of the transformer can be estimated even if a current sensor capable of detecting only the positive polarity is used.
  • the control unit controls the on / off operation of the second switching element based on the estimation result of the estimation unit.
  • the on / off operation of the second switching element can be controlled before the magnetic saturation occurs. Thereby, magnetic saturation of the transformer can be prevented in advance.
  • FIG. 1 is an explanatory view showing an example of a circuit configuration of a power supply device 100 according to the present embodiment.
  • Power supply apparatus 100 of the present embodiment includes terminals A and B on the input side and terminals C and D on the output side, and a DC power supply (not shown) is connected to terminals A and B on the input side.
  • a load is connected to terminals C and D of
  • the power supply device 100 is, for example, a step-down conversion device.
  • the power supply device 100 includes a transformer 30, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor, hereinafter referred to as "FET") 11 as a first switching element, a capacitor 21 as a first capacitor, and a second switching element.
  • the FETs 11 and 12 each have a body diode.
  • a primary winding 31 of the transformer 30 is connected to the terminal A.
  • the drain of the FET 11 is connected to the other end of the primary winding 31.
  • the source of the FET 11 is connected to the terminal B.
  • a capacitor 21 (resonance capacitor) is connected between the drain and source of the FET 11.
  • a current transformer 71 is connected in series to the primary winding 31 of the transformer 30.
  • the current transformer 71 detects the current flowing through the primary winding 31 of the transformer 30, and outputs the detected current to the control unit 50.
  • a series circuit of the FET 12 and the capacitor 22 is connected to both ends of the primary winding 31.
  • a series circuit of the FET 12 and the capacitor 22 constitutes an active clamp circuit.
  • one end of the capacitor 22 is connected to one end of the primary winding 31, and the drain of the FET 12 is connected to the other end of the capacitor 22.
  • the source of the FET 12 is connected to the other end of the primary winding 31.
  • the cathode of the diode 41 is connected to one end of the secondary winding 32 of the transformer 30, and the anode of the diode 41 is connected to the terminal D (ground level).
  • the other end of the secondary winding 32 is connected to the cathode of the diode 42 and one end of the inductor 61.
  • the anode of the diode 42 is connected to the anode of the diode 41.
  • the cathodes of the diode 41 and the diode 42 are connected to each other It may be configured.
  • the other end of the inductor 61 is connected to the terminal C.
  • a capacitor 23 is connected between the terminals C and D.
  • the control unit 50 outputs a gate voltage to the gates of the FETs 11 and 12.
  • the control unit 50 includes a current acquisition unit 51, an estimation unit 52, a storage unit 53, and the like.
  • the current acquisition unit 51 acquires the current of the transformer 30. Specifically, the current acquisition unit 51 acquires the current of the transformer 30 detected by the current transformer 71.
  • the current acquisition unit 51 may be configured to be able to acquire both positive and negative currents, but in the present embodiment, only the positive polarity can be detected.
  • the estimation unit 52 estimates, based on the current acquired by the current acquisition unit 51, whether or not the transformer 30 reaches magnetic saturation.
  • the assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached. Details of the method of estimating the magnetic saturation will be described later.
  • the storage unit 53 stores information such as the current acquired by the current acquisition unit 51 and the duty ratio (the length of the on period) during the switching operation of the FET 11 and the FET 12.
  • FIG. 2 is a time chart which shows an example of the waveform of each part of the power supply device 100 of this Embodiment.
  • the waveforms of the gate voltage of the FET 11, the gate voltage of the FET 12, the current of the transformer 30 (hereinafter also referred to as transformer current), and the excitation current of the transformer 30 (hereinafter also referred to as excitation current) are schematically shown from the top Show. Because the waveforms of the respective parts are schematically illustrated for the sake of convenience, the actual waveforms of the respective parts may be different.
  • the period T is divided into four periods D1, D2, D3 and D4.
  • a period D1 is an on period of the FET 11, and the FET 11 repeats on / off at a predetermined duty ratio (D1 / T).
  • a period D3 is an on period of the FET 12, and the FET 12 repeats on / off at a predetermined duty ratio (D3 / T).
  • Periods D2 and D4 are periods in which both the FET 11 and the FET 12 are turned off.
  • FIG. 3 is an explanatory view showing an example of an operation state of the power supply device 100 of the present embodiment in the period D1.
  • the FET 11 is in the on state
  • the FET 12 is in the off state.
  • the power supply voltage on the input side is applied to the primary winding 31 of the transformer 30, and the voltage of the primary winding 31 becomes positive.
  • the voltage of the secondary winding 32 also becomes positive, and the diode 41 conducts and a load current flows in the load.
  • a total of load current and excitation current flows through the primary winding 31 of the transformer 30.
  • the transformer current (load current + excitation current) and the excitation current increase linearly.
  • the temporal variation of the excitation current corresponds to the temporal variation of the transformer current.
  • the symbol Lm represents the excitation inductance of the transformer 30, and Ls represents the leakage inductance.
  • a positive voltage For convenience, in FIG. 3, a case where the potential at the upper end is higher than the lower end of each of the primary winding 31 and the secondary winding 32 is referred to as a positive voltage.
  • FIG. 4 is an explanatory view showing an example of an operation state of the power supply device 100 of the present embodiment in the period D2.
  • both the FET 11 and the FET 12 are in the off state.
  • the capacitor 21 is charged and the excitation current is maintained.
  • the capacitance of the capacitor 21 is Cs.
  • the voltage of the transformer 30 primary winding 31 and secondary winding 32
  • the load current decreases.
  • the diode 41 becomes reverse biased and becomes nonconductive.
  • the load current flowing in the diode 41 flows through the diode 42.
  • the reduced load current is apparently invisible from the primary side of transformer 30, and the load current viewed from the primary side of transformer 30 is zero.
  • the transformer current acquired by the current acquisition unit 51 is only the excitation current, and the influence of the load current can be removed.
  • FIG. 5 is an explanatory view showing an example of an operation state of the power supply device 100 of the present embodiment in the period D3.
  • the FET 12 is in the on state, and the FET 11 is in the off state.
  • the FET 12 turns from off to on, so the voltage of the capacitor 22 is applied to the transformer 30 in the reverse direction (direction of negative voltage), and the exciting current of the transformer 30 decreases.
  • the excitation current of the transformer 30 is reversed (becomes negative, the current direction is reversed), the energy stored in the capacitor 22 is released, and the energy is stored in the leakage inductance Ls of the transformer 30.
  • FIG. 6 is an explanatory view showing an example of the operation state of the power supply device 100 of the present embodiment in the period D4.
  • the FET 12 and the FET 11 are in the off state.
  • resonance occurs due to the transformer 30 (more specifically, the leakage inductance Ls) and the capacitance Cs.
  • the diode 42 includes a load current Il (indicated by a solid line in the figure) flowing to the load, an excitation current Im of the transformer 30 (indicated by a dashed line in the figure), a resonance of the transformer 30 (leakage inductance Ls of the transformer 30) and a capacitance Cs.
  • a resonant current Ir (indicated by a dot-and-dash line in the figure) flows. That is, the current flowing through the transformer 30 resonates.
  • the load current Il flows through the diode 42, the inductor 61, and the closed loop of the load.
  • the load current I1 has a constant value, for example, by relatively increasing the inductance of the inductor 61.
  • the excitation current Im flows in the closed loop of the transformer 30 and the diodes 42 and 41. Since the voltage applied to the excitation inductance Lm is substantially zero in the period D4, the excitation current Im is maintained.
  • the resonance based on the leakage inductance Ls and the capacitance Cs of the transformer 30 starts from the start of the period D4, and the resonance current Ir is sinusoidal and flows through the capacitor C21 and the transformer 30.
  • the saturation magnetic flux density of the transformer 30 is Bmax
  • the cross-sectional area of the core is A
  • the excitation inductance is Lm
  • the excitation current is Im
  • the number of primary windings 31 of the transformer 30 is n.
  • the condition for magnetically saturating can be expressed by the formula
  • FIG. 7 is an explanatory view showing a first example of a method of estimating the magnetic saturation of the transformer 30 by the power supply device 100 of the present embodiment. From the top, the gate voltage of the FET 11, the gate voltage of the FET 12, and the transformer current are shown.
  • the FET 11 turns from on to off, and in a period D2, both the FET 11 and the FET 12 turn off.
  • the excitation current is maintained at a constant value, but the load current rapidly decreases.
  • the FET 12 turns from off to on, and at the start of the period D3, the load current flowing through the primary winding 31 of the transformer 30 becomes 0 and becomes only the excitation current. That is, the FET 11 is in the OFF state, and the current acquired at the ON time of the FET 12 is only the excitation current, and the influence of the load current can be excluded, and the possibility of magnetic saturation of the transformer 30 can be accurately estimated. Can.
  • the estimation unit 52 estimates whether or not the transformer 30 reaches magnetic saturation based on the current obtained when the FET 11 is off and the FET 12 is on.
  • the assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached.
  • the control unit 50 controls the on / off operation of the FET 11 or the FET 12 based on the estimation result of the estimation unit 52.
  • the on / off operation of the FET 11 or FET 12 can be controlled before magnetic saturation occurs. Thereby, magnetic saturation of the transformer 30 can be prevented in advance.
  • the estimation unit 52 determines that the transformer 30 has reached magnetic saturation. presume.
  • the control unit 50 stops the on / off operation of the FET 11 and the FET 12 when the current Im is larger than the first threshold Ith1.
  • the switching operation is stopped if it is estimated that the magnetic saturation state occurs. Thereby, it is possible to prevent in advance the magnetic saturation due to the positive side excitation current when the transformer 30 is excited.
  • FIG. 8 is an explanatory view showing a second example of the method of estimating the magnetic saturation of the transformer 30 by the power supply device 100 of the present embodiment. From the top, the gate voltage of the FET 11, the gate voltage of the FET 12, and the transformer current are shown. In FIG. 8, time t15 to time t19 is one switching cycle, and time t11 to time t15 is a switching cycle one cycle earlier than the one switching cycle.
  • the current acquisition unit 51 sets the current (excitation current) acquired at the ON time point (time point t17) of the FET 12 to Im (n) when the FET 11 is off in one switching cycle. Further, the current (excitation current) acquired at the ON time point (time point t13) of the FET 12 when the current acquisition unit 51 is in the OFF state of the FET 11 in the switching cycle earlier than the one switching cycle is Im (n ⁇ 1) As described above, the transformer current acquired at time t13 and time t17 does not include the load current but is only the excitation current.
  • the current Im (n) is equal to or less than the first threshold Ith1, and ⁇ Im (n) / Im (n-1) ⁇ is ⁇ D1 (n-1) / D1 (n-2). If it is larger than ⁇ ⁇ Th1, it is estimated that the transformer 30 reaches magnetic saturation.
  • the control unit 50 determines that the current Im (n) is equal to or less than the first threshold Ith1 and ⁇ Im (n) / Im (n-1) ⁇ is ⁇ D1 (n-1) / D1 (n-2) ⁇ ⁇ If larger than Th1, the on / off operation is controlled so that the on period of the FET 11 becomes short.
  • the current of the primary winding 31 of the transformer 30 may increase with the passage of the switching period and lead to magnetic saturation, it is possible to adjust the duty ratio (on period) of the FET 11. For example, when it is possible to avoid the magnetic saturation state, the on / off operation is controlled so that the on period of the FET 11 becomes short without stopping the switching operation. As a result, magnetic saturation can be prevented in advance without stopping the operation of the power supply device 100.
  • ⁇ Im (n) / Im (n-1) ⁇ is larger than ⁇ D1 (n-1) / D1 (n-2) ⁇ ⁇ Th1 at the time of magnetic saturation estimation.
  • ⁇ Im (n) / Im (n-1) ⁇ is larger than Th1.
  • the on period (D1) of the FET 11 is increased, the excitation current on the positive side increases, and if the on period (D1) of the FET 11 is shortened, the excitation current on the positive side decreases.
  • FIG. 9 is an explanatory view showing a third example of the method of estimating the magnetic saturation of the transformer 30 by the power supply device 100 of the present embodiment. From the top, the gate voltage of the FET 11, the gate voltage of the FET 12, and the transformer current are shown.
  • the amplitude of the resonant current increases when the magnetic flux balance breaks down as a sign of reaching magnetic saturation, and thus acquired at a time (for example, a required time during resonance) when a predetermined time has elapsed from the start time of the period D4 (time t4). Based on the current (ie, the resonant current), the likelihood of magnetic saturation of the transformer 30 can be accurately estimated.
  • the resonance current resonates on both the positive side and the negative side with current 0 in between, if the amplitude on the positive side of the resonance current is detected, the amplitude on the negative side of the resonance current can be estimated. Therefore, even if a current sensor capable of detecting only the positive polarity is used, magnetic saturation due to the negative excitation current when resetting the excitation of the transformer 30 can be estimated.
  • the estimation unit 52 estimates whether or not the transformer 30 reaches magnetic saturation based on the current acquired when the FET 11 is off and a predetermined time has elapsed from the off time of the FET 12.
  • the assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached.
  • the control unit 50 controls the on / off operation of the FET 11 or the FET 12 based on the estimation result of the estimation unit 52.
  • the on / off operation of the FET 11 or FET 12 can be controlled before magnetic saturation occurs. Thereby, magnetic saturation of the transformer 30 can be prevented in advance.
  • the estimation unit 52 determines that the current Im1 acquired at a time (for example, a time corresponding to a quarter of the resonance period Td) when a predetermined time has elapsed from the OFF time (time t4) of the FET 12 is When it is larger than the third threshold Ith2, it is estimated that the transformer 30 reaches magnetic saturation.
  • the control unit stops the on / off operation of the FET 11 and the FET 12 when the current Im1 is larger than the third threshold Ith2.
  • the switching operation is stopped if it is estimated that the magnetic saturation state occurs. Thereby, even when using a current sensor which can not detect the negative polarity, it is possible to prevent in advance the magnetic saturation due to the negative excitation current when the excitation of the transformer 30 is reset.
  • the above-mentioned predetermined time can be a time of 1 ⁇ 4 of the resonance period Td depending on the leakage inductance Ls of the transformer 30 and the capacitance Cs of the capacitor 21 and a time near the time.
  • the resonance current has a sine wave shape
  • the time from the peak Im2 of the negative amplitude of the resonance current to the peak Im1 of the positive amplitude corresponds to a quarter of the resonance period Td.
  • the peak Im2 of the negative side amplitude of the resonance current is equal to the peak Im1 of the positive side amplitude. Therefore, if the current Im1 at the point of Td / 4 from the point of the peak of the amplitude on the negative side of the resonance current is detected, it is possible to estimate the peak Im2 of the amplitude on the negative side.
  • the point at which the amplitude on the negative side of the resonance current peaks is at the point when the FET 12 is off (that is, at the start of the period D4).
  • the vicinity time can be, for example, a time in consideration of the dispersion of the resonance period Td in consideration of the dispersion of the leakage inductance Ls of the transformer 30 and the capacitance Cs of the capacitor 21.
  • a current sensor capable of detecting only the positive polarity it is possible to prevent in advance the magnetic saturation due to the negative excitation current when the excitation of the transformer 30 is reset.
  • a current sensor capable of detecting a negative current needs to include a circuit for converting the current to a positive polarity, an amplification circuit, and the like, which is generally expensive. Since a current sensor capable of detecting only positive polarity can be used, it contributes to cost reduction.
  • FIG. 10 is an explanatory view showing a fourth example of the method of estimating the magnetic saturation of the transformer 30 by the power supply device 100 of the present embodiment.
  • the estimation unit 52 determines that the transformer 30 has reached magnetic saturation. presume.
  • control unit 50 controls the on / off operation so that the on period of the FET 12 becomes short.
  • the current (that is, the resonance current) of the primary winding 31 of the transformer 30 may increase with the passage of the switching period and lead to magnetic saturation, if the duty ratio (on period) of the FET 12 is adjusted, If it is possible to avoid saturation, the on / off operation is controlled such that the on period of the FET 12 becomes short without stopping the switching operation. Thereby, the magnetic saturation of the transformer 30 can be prevented in advance without stopping the power supply device 100.
  • FIG. 11 is a flow chart showing a first example of the processing procedure of the control method of the power supply device 100 of the present embodiment.
  • the control unit 50 performs switching of the FET 11 and the FET 12 based on a predetermined duty ratio (S11).
  • the control unit 50 determines whether or not the FET 12 is turned on from off (S12), and when the FET 12 is not turned on (NO in S12), the process of step S12 is continued. Since the control unit 50 controls the output of the gate voltage for turning on the FETs 11 and 12, the ON point and the OFF point of the FET 11 and the FET 12 can be known.
  • the control unit 50 acquires a transformer current (corresponding to the excitation current) (S13), and whether or not the acquired transformer current is larger than the current threshold (first threshold) Is determined (S14). If the transformer current is larger than the current threshold (YES in S14), the control unit 50 stops the switching operation of the FET 11 and the FET 12 (S15), and ends the processing.
  • the control unit 50 sets the ratio of the ratio of the transformer current acquired this time to the transformer current acquired when the FET 12 is turned on from one period ago earlier It is determined whether it is larger than the second threshold) (S16). If the ratio of the transformer current is larger than the threshold (YES in S16), the control unit 50 shortens the on period of the FET 11 (S17), and performs the process of step S19 described later.
  • control unit 50 records the transformer current acquired this time in the storage unit 53 (S18), and determines whether to end the process (S19) .
  • the control unit 10 continues the process after step S11.
  • the control unit 10 ends the process.
  • FIG. 12 is a flowchart illustrating a second example of the processing procedure of the control method of the power supply device 100 according to the present embodiment.
  • the control unit 50 performs switching of the FET 11 and the FET 12 based on a predetermined duty ratio (S31).
  • the control unit 50 determines whether or not a predetermined time has elapsed from the time when the FET 12 is off (S32), and continues the process of step S32 when the predetermined time has not elapsed (NO in S32).
  • the control unit 50 acquires a transformer current (corresponding to a resonant current) (S33), and determines whether the acquired transformer current is larger than the current threshold (third threshold). It determines (S34). If the transformer current is larger than the current threshold (YES in S34), the control unit 50 stops the switching operation of the FET 11 and the FET 12 (S35), and ends the processing.
  • the control unit 50 sets the ratio of the ratio of the transformer current acquired this time to the transformer current acquired when a predetermined time has elapsed from the OFF point of one period ago. It is determined whether the threshold is greater than 4) (S36). If the ratio of the transformer current is larger than the threshold (YES in S36), the control unit 50 shortens the on period of the FET 12 (S37), and performs the process of step S39 described later.
  • control unit 50 records the transformer current acquired this time in the storage unit 53 (S38), and determines whether to end the process (S39) .
  • the control unit 10 continues the process after step S31.
  • the control unit 10 ends the process.
  • control unit 50 includes, for example, a CPU (processor), a RAM (memory), and the like, and determines the procedure of each process as shown in FIGS.
  • CPU processor
  • RAM memory
  • FIGS By loading the computer program into the RAM (memory) and executing the computer program by the CPU (processor), the control method of the power supply apparatus 100 can be realized on the computer.
  • the switching element is not limited to the MOSFET, and may be a device such as an IGBT (Insulated Gate Bipolar Transistor).
  • IGBT Insulated Gate Bipolar Transistor
  • the switching element when the switching element is a MOSFET, there is a body diode built in equivalently between the drain and the source.
  • a bipolar transistor When a bipolar transistor is used as a switching element, a diode may be connected in anti-parallel between the collector and the emitter of the transistor.
  • the configuration of the DC / DC converter as shown in FIG. 1 is described as an example of the power supply device, but the configuration of the DC / DC converter is limited to the configuration illustrated in FIG. Instead, the switching element may be connected in series to the primary winding of the transformer, and the magnetic reset of the transformer may be performed.
  • FIG. 13 is an explanatory view showing another example of the circuit configuration of the power supply device 120 according to the present embodiment.
  • the power supply device 100 shown in FIG. 1 described above is configured to include the active clamp circuit, but the present embodiment can also be applied to a power supply device that does not include the active clamp circuit.
  • the difference from the power supply device 100 shown in FIG. 1 is that the voltage sensors 72 and 73 and the voltage acquisition unit 54 are provided.
  • a capacitor C11 may be a floating capacitance
  • a capacitor C13 is provided, and further, a capacitor C12 (may be a floating capacitance).
  • the FET 12 and the capacitor C13 do not constitute an active clamp circuit.
  • the voltage acquisition unit 54 acquires an input voltage (DC) detected by the voltage sensor 72 and an output voltage (DC) detected by the voltage sensor 73.
  • the control unit 50 controls switching of the FET 11 and the FET 12 based on the voltage acquired by the voltage acquisition unit 54 so that the output voltage becomes a target value.
  • the operation of the power supply device 120 shown in FIG. 13 is the same as the operation of the power supply device 100 shown in FIG.
  • the current acquisition unit 51 acquires the current flowing through the primary winding 31 of the transformer 30.
  • the estimation unit 52 estimates whether or not the transformer 30 reaches magnetic saturation based on the current acquired at the on time of the FET 12. Further, the estimation unit 52 estimates whether or not the transformer 30 reaches magnetic saturation based on the acquired current when a predetermined time has elapsed from the time when the FET 12 is turned off.
  • the assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached.
  • a voltage on the input side is applied to the primary winding 31 of the transformer 30, and a total of load current and excitation current flows through the primary winding 31 of the transformer 30.
  • the load current flowing through the primary winding 31 of the transformer 30 is zero and only the excitation current. Therefore, the current acquired at the ON time of the FET 12 is only the excitation current, and the influence of the load current can be excluded to accurately estimate the possibility of the magnetic saturation of the transformer 30.
  • the resonance current resonates on both the positive side and the negative side with current 0 in between, if the amplitude on the positive side of the resonance current is detected, the amplitude on the negative side of the resonance current can be estimated. Therefore, magnetic saturation due to the excitation current on the negative side of the transformer 30 can be estimated even if a current sensor capable of detecting only the positive polarity is used.
  • the control unit 50 controls the on / off operation of the FET 12 based on the estimation result of the estimation unit 52.
  • the on / off operation of the FET 12 can be controlled before the magnetic saturation occurs. Thereby, magnetic saturation of the transformer 30 can be prevented in advance.

Abstract

This power supply device is provided with: a current acquisition unit which acquires a current of a transformer; and an estimation unit which, on the basis of the current acquired by the current acquisition unit at a point in time when a first switching element is in off-state and a second switching element is on, or a point in time at which a predetermined time has elapsed from a point in time when the second switching element was off, estimates whether the transformer will reach magnetic saturation. A control unit controls the on/off operation of the first switching element or the second switching element on the basis of the result of estimation performed by the estimation unit.

Description

電源装置及び電源装置の制御方法POWER SUPPLY DEVICE AND CONTROL METHOD OF POWER SUPPLY DEVICE
　本開示は、電源装置及び電源装置の制御方法に関する。
　本出願は、２０１７年１２月２６日出願の日本出願第２０１７－２４９９０９号に基づく優先権を主張し、前記日本出願に記載された全ての記載内容を援用するものである。 The present disclosure relates to a power supply device and a control method of the power supply device.
This application claims priority based on Japanese Patent Application No. 2017-249909 filed on Dec. 26, 2017, and incorporates all the contents described in the aforementioned Japanese application.
　直流電圧を変換するＤＣ／ＤＣコンバータが産業用機器及び車載装置に用いられている。ＤＣ／ＤＣコンバータには、アクティブクランプ型のＤＣ／ＤＣコンバータがある。アクティブクランプ型のＤＣ／ＤＣコンバータは、トランスの一次巻線と主スイッチング素子との直列回路が直流電源に接続され、一次巻線の両端にキャパシタと補助スイッチング素子とからなるアクティブクランプ回路が接続されている。そして、主スイッチング素子と補助スイッチング素子とを所要のデューティ比で交互にオン／オフすることによって、トランスの磁化エネルギー及び漏れエネルギーをアクティブクランプ回路のキャパシタを介して循環させ、電源変換効率を向上させることができる。 BACKGROUND A DC / DC converter that converts a DC voltage is used in industrial equipment and in-vehicle devices. The DC / DC converter includes an active clamp type DC / DC converter. In an active clamp type DC / DC converter, a series circuit of a primary winding of a transformer and a main switching element is connected to a DC power supply, and an active clamp circuit consisting of a capacitor and an auxiliary switching element is connected across the primary winding. ing. Then, by alternately turning on / off the main switching element and the auxiliary switching element at a required duty ratio, magnetization energy and leakage energy of the transformer are circulated through the capacitor of the active clamp circuit to improve the power supply conversion efficiency. be able to.
　特許文献１には、トランスの一次側電流の瞬時値を検出し、検出した瞬時値と過去の瞬時値の平均値との差分を求め、その差分が所定値以上である場合、トランスの励磁動作を停止させて磁気リセットを行うＤＣ／ＤＣコンバータが開示されている。 In Patent Document 1, the instantaneous value of the primary side current of the transformer is detected, and the difference between the detected instantaneous value and the average value of the instantaneous values in the past is determined. If the difference is equal to or more than a predetermined value, the excitation operation of the transformer Discloses a DC / DC converter that performs a magnetic reset by stopping the
特開２００８－１９９８７８号公報JP, 2008-199878, A
　本開示の実施の形態に係る電源装置は、トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、該第１のスイッチング素子に並列に接続された第１のキャパシタと、前記一次巻線に並列に接続された第２のスイッチング素子及び第２のキャパシタの直列回路と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置であって、前記トランスの電流を取得する電流取得部と、前記第１のスイッチング素子がオフ状態であって、前記第２のスイッチング素子のオン時点にて又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて前記電流取得部で取得した電流に基づいて、前記トランスが磁気飽和に至るか否かを推定する推定部とを備え、前記制御部は、前記推定部の推定結果に基づいて前記第１のスイッチング素子又は第２のスイッチング素子のオン／オフ動作を制御する。 A power supply device according to an embodiment of the present disclosure includes a transformer, a first switching element connected in series to a primary winding of the transformer, and a first capacitor connected in parallel to the first switching element. And a series circuit of a second switching element and a second capacitor connected in parallel to the primary winding, and turning on / off the first switching element and the second switching element in a predetermined switching cycle. A current acquisition unit for acquiring the current of the transformer, the first switching element being in the OFF state, and the second switching element being turned on, or Whether or not the transformer reaches magnetic saturation based on the current acquired by the current acquisition unit when a predetermined time has elapsed from the turning-off time of the switching element 2 And a estimation unit that estimates for the control unit controls the on / off operation of the first switching element or the second switching element based on an estimation result of the estimation unit.
　本開示の実施の形態に係る電源装置は、トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、前記一次巻線に並列に接続された第２のスイッチング素子と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置であって、前記トランスの電流を取得する電流取得部と、前記第２のスイッチング素子のオン時点又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて前記電流取得部で取得した電流に基づいて、前記トランスが磁気飽和に至るか否かを推定する推定部とを備え、前記制御部は、前記推定部の推定結果に基づいて前記第２のスイッチング素子のオン／オフ動作を制御する。 A power supply device according to an embodiment of the present disclosure includes a transformer, a first switching element connected in series to a primary winding of the transformer, and a second switching element connected in parallel to the primary winding. A control unit configured to turn on / off the first switching element and the second switching element in a predetermined switching cycle, the current acquisition unit acquiring the current of the transformer, and Whether or not the transformer reaches magnetic saturation based on the current acquired by the current acquisition unit when a predetermined time has elapsed from the time when the switching element is turned on or when the second switching element is turned off An estimation unit is provided, and the control unit controls the on / off operation of the second switching element based on the estimation result of the estimation unit.
　本開示の実施の形態に係る電源装置の制御方法は、トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、該第１のスイッチング素子に並列に接続された第１のキャパシタと、前記一次巻線に並列に接続された第２のスイッチング素子及び第２のキャパシタの直列回路と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置の制御方法であって、前記トランスの電流を取得し、前記第１のスイッチング素子がオフ状態であって、前記第２のスイッチング素子のオン時点にて又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて、取得された電流に基づいて、前記トランスが磁気飽和に至るか否かを推定し、前記制御部は、推定結果に基づいて前記第１のスイッチング素子又は第２のスイッチング素子のオン／オフ動作を制御する。 In a control method of a power supply device according to an embodiment of the present disclosure, a transformer, a first switching element connected in series to a primary winding of the transformer, and a second switching element connected in parallel to the first switching element , A series circuit of a second switching element and a second capacitor connected in parallel to the primary winding, and the first switching element and the second switching element on / off in a predetermined switching cycle. A control method of a power supply device, comprising: a control unit configured to perform an off operation, wherein a current of the transformer is acquired, the first switching element is in an off state, and the second switching element is turned on or Based on the acquired current, it is estimated whether or not the transformer reaches magnetic saturation when a predetermined time has elapsed since the second switching element is turned off. , The control unit controls the on / off operation of the first switching element or the second switching element based on the estimation result.
　本開示の実施の形態に係る電源装置の制御方法は、トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、前記一次巻線に並列に接続された第２のスイッチング素子と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置の制御方法であって、前記トランスの電流を取得し、前記第２のスイッチング素子のオン時点又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて、取得された電流に基づいて、前記トランスが磁気飽和に至るか否かを推定し、前記制御部は、推定結果に基づいて前記第２のスイッチング素子のオン／オフ動作を制御する。 In a control method of a power supply device according to an embodiment of the present disclosure, a transformer, a first switching element connected in series to a primary winding of the transformer, and a second switch connected in parallel to the primary winding. A control method of a power supply device, comprising: a switching element; and a control unit for turning on / off the first switching element and the second switching element in a predetermined switching cycle, obtaining a current of the transformer, Whether or not the transformer reaches magnetic saturation is estimated based on the acquired current when a predetermined time elapses from the on time of the second switching element or the off time of the second switching element, The control unit controls the on / off operation of the second switching element based on the estimation result.
本実施の形態の電源装置の回路構成の一例を示す説明図である。It is an explanatory view showing an example of circuit composition of a power supply device of this embodiment. 本実施の形態の電源装置の各部の波形の一例を示すタイムチャートである。It is a time chart which shows an example of a waveform of each part of a power supply device of this embodiment. 本実施の形態の電源装置の期間Ｄ１での動作状態の一例を示す説明図である。It is explanatory drawing which shows an example of the operation state in period D1 of the power supply device of this Embodiment. 本実施の形態の電源装置期間Ｄ２での動作状態の一例を示す説明図である。It is explanatory drawing which shows an example of the operation state in power supply apparatus period D2 of this Embodiment. 本実施の形態の電源装置期間Ｄ３での動作状態の一例を示す説明図である。It is explanatory drawing which shows an example of the operation state in the power supply apparatus period D3 of this Embodiment. 本実施の形態の電源装置期間Ｄ４での動作状態の一例を示す説明図である。It is explanatory drawing which shows an example of the operation state in power supply apparatus period D4 of this Embodiment. 本実施の形態の電源装置によるトランスの磁気飽和の推定方法の第１例を示す説明図である。It is explanatory drawing which shows the 1st example of the estimation method of the magnetic saturation of the transformer by the power supply device of this Embodiment. 本実施の形態の電源装置によるトランスの磁気飽和の推定方法の第２例を示す説明図である。It is explanatory drawing which shows the 2nd example of the estimation method of the magnetic saturation of the transformer by the power supply device of this Embodiment. 本実施の形態の電源装置によるトランスの磁気飽和の推定方法の第３例を示す説明図である。It is explanatory drawing which shows the 3rd example of the estimation method of the magnetic saturation of the transformer by the power supply device of this Embodiment. 本実施の形態の電源装置によるトランスの磁気飽和の推定方法の第４例を示す説明図である。It is explanatory drawing which shows the 4th example of the estimation method of the magnetic saturation of the transformer by the power supply device of this Embodiment. 本実施の形態の電源装置の制御方法の処理手順の第１例を示すフローチャートである。It is a flowchart which shows the 1st example of a process procedure of the control method of the power supply device of this Embodiment. 本実施の形態の電源装置の制御方法の処理手順の第２例を示すフローチャートである。It is a flowchart which shows the 2nd example of a process procedure of the control method of the power supply device of this Embodiment. 本実施の形態の電源装置の回路構成の他の例を示す説明図である。It is explanatory drawing which shows the other example of the circuit structure of the power supply device of this Embodiment.
［本開示が解決しようとする課題］
　しかし、特許文献１のＤＣ／ＤＣコンバータでは、トランスの一次側電流の瞬時値を検出するので、トランスの励磁電流だけでなく負荷電流も検出する。一般的に負荷電流は励磁電流よりも大きいので、磁気飽和を判定する際に負荷電流の影響が大きくなる。このため、磁気飽和に至るまでには余裕があるにもかかわらず、負荷電流の影響で磁気飽和に至ったと判定するおそれがある。 [Problems to be solved by the present disclosure]
However, in the DC / DC converter of Patent Document 1, since the instantaneous value of the primary side current of the transformer is detected, not only the excitation current of the transformer but also the load current is detected. In general, since the load current is larger than the excitation current, the influence of the load current is large when determining the magnetic saturation. Therefore, although there is a margin until reaching magnetic saturation, it may be determined that magnetic saturation has been reached due to the influence of load current.
　そこで、トランスの磁気飽和を未然に防止することができる電源装置及び電源装置の制御方法を提供することを目的とする。
［本開示の効果］ Therefore, it is an object of the present invention to provide a power supply device and a control method of the power supply device capable of preventing magnetic saturation of a transformer in advance.
[Effect of the present disclosure]
　本開示によれば、トランスの磁気飽和を未然に防止することができる。 According to the present disclosure, magnetic saturation of the transformer can be prevented in advance.
［本願開示の実施形態の説明］
　本実施の形態に係る電源装置は、トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、該第１のスイッチング素子に並列に接続された第１のキャパシタと、前記一次巻線に並列に接続された第２のスイッチング素子及び第２のキャパシタの直列回路と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置であって、前記トランスの電流を取得する電流取得部と、前記第１のスイッチング素子がオフ状態であって、前記第２のスイッチング素子のオン時点にて又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて前記電流取得部で取得した電流に基づいて、前記トランスが磁気飽和に至るか否かを推定する推定部とを備え、前記制御部は、前記推定部の推定結果に基づいて前記第１のスイッチング素子又は第２のスイッチング素子のオン／オフ動作を制御する。 [Description of the embodiment of the present disclosure]
The power supply device according to the present embodiment includes a transformer, a first switching element connected in series to a primary winding of the transformer, and a first capacitor connected in parallel to the first switching element. A control circuit that turns on / off the first switching element and the second switching element in a predetermined switching cycle, and a series circuit of a second switching element and a second capacitor connected in parallel to the primary winding. A current acquisition unit for acquiring the current of the transformer, and the first switching element is in the OFF state, and the second switching element is turned on or when the second switching element is turned on. Whether or not the transformer reaches magnetic saturation is estimated based on the current acquired by the current acquisition unit when a predetermined time has elapsed since the switching element was turned off. And a estimation unit, wherein the control unit controls the on / off operation of the first switching element or the second switching element based on an estimation result of the estimation unit.
　本実施の形態に係る電源装置の制御方法は、トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、該第１のスイッチング素子に並列に接続された第１のキャパシタと、前記一次巻線に並列に接続された第２のスイッチング素子及び第２のキャパシタの直列回路と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置の制御方法であって、前記トランスの電流を取得し、前記第１のスイッチング素子がオフ状態であって、前記第２のスイッチング素子のオン時点にて又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて、取得された電流に基づいて、前記トランスが磁気飽和に至るか否かを推定し、前記制御部は、推定結果に基づいて前記第１のスイッチング素子又は第２のスイッチング素子のオン／オフ動作を制御する。 A control method of a power supply device according to the present embodiment includes a transformer, a first switching element connected in series to a primary winding of the transformer, and a first switching element connected in parallel to the first switching element. ON / OFF operation of a capacitor, a series circuit of a second switching element and a second capacitor connected in parallel to the primary winding, and the first switching element and the second switching element in a predetermined switching cycle And a control unit for controlling the power supply device, wherein the current of the transformer is acquired, the first switching element is in the off state, and the second switching element is turned on or when the first switching element is turned on. At the time when a predetermined time has elapsed from the time when the switching element 2 is turned off, it is estimated whether the transformer reaches magnetic saturation or not based on the acquired current. The control unit controls the on / off operation of the first switching element or the second switching element based on the estimation result.
　電流取得部は、トランスの電流を取得する。 The current acquisition unit acquires the current of the transformer.
　推定部は、第１のスイッチング素子がオフ状態であって、第２のスイッチング素子のオン時点にて取得した電流に基づいて、トランスが磁気飽和に至るか否かを推定する。また、推定部は、第１のスイッチング素子がオフ状態であって、第２のスイッチング素子のオフ時点から所定時間が経過した時点にて取得した電流に基づいて、トランスが磁気飽和に至るか否かを推定する。なお、磁気飽和に至ると推定するとは、まだ磁気飽和に至っていない状態での推定である。 The estimation unit estimates whether or not the transformer reaches magnetic saturation based on the current acquired when the first switching element is in the off state and the second switching element is on. Further, the estimation unit determines whether or not the transformer is magnetically saturated based on the current acquired when the first switching element is in the off state and a predetermined time has elapsed from the time when the second switching element is off. To estimate. The assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached.
　第１のスイッチング素子がオン状態であって、第２スイッチング素子がオフ状態（期間Ｄ１と称する）では、トランスの一次巻線には入力側の電圧が印加され、トランスの一次巻線には、負荷電流及び励磁電流の合計が流れる。 When the first switching element is in the on state and the second switching element is in the off state (referred to as period D1), a voltage on the input side is applied to the primary winding of the transformer, and the primary winding of the transformer is The sum of the load current and the excitation current flows.
　第１のスイッチング素子がオフとなり、第１のスイッチング素子及び第２スイッチング素子の両者がオフ状態（期間Ｄ２と称する）では、励磁電流は一定値に維持されるが負荷電流は減少する。 When the first switching element is turned off and both the first switching element and the second switching element are turned off (referred to as period D2), the excitation current is maintained at a constant value but the load current is decreased.
　第１のスイッチング素子がオフ状態であって、第２のスイッチング素子のオン時点（期間Ｄ２の終了時点、期間Ｄ３の開始時点）では、トランスの一次巻線に流れる負荷電流は０となり励磁電流だけになる。そこで、第１のスイッチング素子がオフ状態であって、第２のスイッチング素子のオン時点にて取得した電流は励磁電流だけとなり、負荷電流の影響を除外してトランスの磁気飽和の可能性を正確に推定することができる。 At the time when the first switching element is off and the second switching element is on (at the end of period D2, at the start of period D3), the load current flowing through the primary winding of the transformer is 0 and only the excitation current become. Therefore, the first switching element is in the off state, and the current acquired at the on time of the second switching element is only the excitation current, and the influence of the load current is excluded to accurately determine the possibility of magnetic saturation of the transformer. Can be estimated.
　第１のスイッチング素子がオフ状態であって、第２のスイッチング素子がオン状態（期間Ｄ３と称する）では、トランスの励磁電流は減少し、トランスの励磁をリセットする状態に移行する。 When the first switching element is in the off state and the second switching element is in the on state (referred to as a period D3), the excitation current of the transformer decreases and the excitation of the transformer is reset.
　第２のスイッチング素子がオフとなり、第１のスイッチング素子及び第２スイッチング素子の両者がオフ状態（期間Ｄ４と称する）では、トランスの漏れインダクタンス及び第１のキャパシタのキャパシタンスに依拠する共振が発生し、トランスの一次巻線には共振電流が流れる。磁気飽和に至る予兆として磁束バランスが崩れると共振電流の振幅が増加するので、第１のスイッチング素子がオフ状態であって、第２のスイッチング素子のオフ時点から所定時間が経過した時点（例えば、共振中の所要の時点）にて取得した電流（すなわち共振電流）に基づいて、トランスの磁気飽和の可能性を正確に推定することができる。 When the second switching element is turned off and both the first switching element and the second switching element are turned off (referred to as period D4), resonance occurs due to the leakage inductance of the transformer and the capacitance of the first capacitor. Resonant current flows in the primary winding of the transformer. When the magnetic flux balance is broken as a sign of reaching magnetic saturation, the amplitude of the resonant current increases, so that the first switching element is in the OFF state, and a predetermined time has elapsed from the time when the second switching element is off (for example, The possibility of magnetic saturation of the transformer can be accurately estimated on the basis of the current obtained at the required point in resonance (ie the resonant current).
　また、共振電流は、電流０を間にして正側と負側の両方に共振するので、共振電流の正側の振幅を検出すれば、共振電流の負側の振幅を推定することができる。従って、正極性のみ検知可能な電流センサを用いても、トランスの励磁をリセットするときの負側の励磁電流による磁気飽和を推定することができる。 In addition, since the resonance current resonates on both the positive side and the negative side with current 0 in between, if the amplitude on the positive side of the resonance current is detected, the amplitude on the negative side of the resonance current can be estimated. Therefore, even if a current sensor capable of detecting only the positive polarity is used, magnetic saturation due to the negative excitation current when resetting the transformer excitation can be estimated.
　制御部は、推定部の推定結果に基づいて第１のスイッチング素子又は第２のスイッチング素子のオン／オフ動作を制御する。磁気飽和となる前に第１のスイッチング素子又は第２のスイッチング素子のオン／オフ動作を制御することができる。これにより、トランスの磁気飽和を未然に防止することができる。 The control unit controls the on / off operation of the first switching element or the second switching element based on the estimation result of the estimation unit. The on / off operation of the first switching element or the second switching element can be controlled before magnetic saturation occurs. Thereby, magnetic saturation of the transformer can be prevented in advance.
　本実施の形態に係る電源装置において、前記推定部は、前記第２のスイッチング素子のオン時点にて前記電流取得部で取得した電流と、第１閾値とに基づいて、前記トランスが磁気飽和に至ると推定し、前記制御部は、前記第１のスイッチング素子及び第２のスイッチング素子のオン／オフ動作を停止する。 In the power supply device according to the present embodiment, the estimation unit causes the transformer to be magnetically saturated based on the current acquired by the current acquisition unit at the time when the second switching element is turned on and the first threshold. It is presumed that the control unit stops the on / off operation of the first switching element and the second switching element.
　推定部は、第２のスイッチング素子のオン時点にて、取得した電流と、第１閾値とに基づいて、トランスが磁気飽和に至ると推定する。 The estimation unit estimates that the transformer reaches magnetic saturation based on the acquired current and the first threshold when the second switching element is turned on.
　制御部は、第１のスイッチング素子及び第２のスイッチング素子のオン／オフ動作を停止する。磁気飽和に至る可能性が高く、第１のスイッチング素子のデューティ比（オン期間）を調整してもスイッチング動作を継続すれば、磁気飽和状態に陥ると推定される場合には、スイッチング動作を停止する。これにより、トランスを励磁する場合の正側の励磁電流による磁気飽和を未然に防止することができる。 The control unit stops the on / off operation of the first switching element and the second switching element. If there is a high possibility of magnetic saturation and the switching operation is continued even if the duty ratio (on period) of the first switching element is adjusted, the switching operation is stopped if it is estimated that the magnetic saturation will occur. Do. Thereby, it is possible to prevent in advance the magnetic saturation due to the positive side excitation current when exciting the transformer.
　本実施の形態に係る電源装置において、前記推定部は、一のスイッチング周期で前記第２のスイッチング素子のオン時点にて前記電流取得部で取得した第１電流と、第１閾値とに基づくとともに、前記第１電流と、前記一のスイッチング周期よりも前のスイッチング周期で前記第２のスイッチング素子のオン時点にて前記電流取得部で取得した第２電流との比と、第２閾値とに基づいて、前記トランスが磁気飽和に至ると推定し、前記制御部は、前記第１のスイッチング素子のオン期間が短くなるようにオン／オフ動作を制御する。 In the power supply device according to the present embodiment, the estimation unit is based on the first current acquired by the current acquisition unit at the on time of the second switching element in one switching cycle, and the first threshold. A ratio of the first current to the second current acquired by the current acquisition unit at the on time of the second switching element in a switching cycle earlier than the one switching cycle, and a second threshold value; Based on the above, it is estimated that the transformer reaches magnetic saturation, and the control unit controls the on / off operation so that the on period of the first switching element becomes short.
　推定部は、一のスイッチング周期で第２のスイッチング素子のオン時点にて、取得した第１電流と、第１閾値とに基づくとともに、当該一のスイッチング周期の第１電流と、当該一のスイッチング周期よりも前のスイッチング周期で第２のスイッチング素子のオン時点にて取得した第２電流との比と、第２閾値とに基づいて、トランスが磁気飽和に至ると推定する。 The estimation unit is based on the acquired first current and the first threshold at the on time point of the second switching element in one switching cycle, and the first current of the one switching cycle and the one switching Based on the ratio to the second current acquired at the on time of the second switching element in the switching cycle earlier than the cycle, and the second threshold, it is estimated that the transformer will reach magnetic saturation.
　制御部は、第１のスイッチング素子のオン期間が短くなるようにオン／オフ動作を制御する。トランスの一次巻線の電流（すなわち、トランスの励磁電流）が、スイッチング周期の経過に伴って増加し磁気飽和に至る可能性があるものの、第１のスイッチング素子のデューティ比（オン期間）を調整すれば、磁気飽和状態に陥ることを回避できる場合には、スイッチング動作を停止せずに、第１のスイッチング素子のオン期間が短くなるようにオン／オフ動作を制御する。これにより、磁気飽和を未然に防止することができる。 The control unit controls the on / off operation such that the on period of the first switching element becomes short. Although the current of the primary winding of the transformer (that is, the excitation current of the transformer) increases with the passage of the switching cycle and may lead to magnetic saturation, the duty ratio (on period) of the first switching element is adjusted If it is possible to avoid the magnetic saturation state, the on / off operation is controlled so that the on period of the first switching element becomes short without stopping the switching operation. Thereby, magnetic saturation can be prevented in advance.
　本実施の形態に係る電源装置において、前記推定部は、前記第２のスイッチング素子のオフ時点から前記所定時間が経過した時点にて前記電流取得部で取得した電流と、第３閾値とに基づいて、前記トランスが磁気飽和に至ると推定し、前記制御部は、前記第１のスイッチング素子及び第２のスイッチング素子のオン／オフ動作を停止する。 In the power supply device according to the present embodiment, the estimation unit is based on the current acquired by the current acquisition unit at the time when the predetermined time has elapsed from the time when the second switching element is turned off and the third threshold. It is estimated that the transformer has reached magnetic saturation, and the control unit stops the on / off operation of the first switching element and the second switching element.
　推定部は、第２のスイッチング素子のオフ時点から所定時間が経過した時点にて取得した電流と、第３閾値とに基づいて、トランスが磁気飽和に至ると推定する。 The estimation unit estimates that the transformer reaches magnetic saturation based on the current acquired when a predetermined time has elapsed from the off time of the second switching element and the third threshold.
　制御部は、第１のスイッチング素子及び第２のスイッチング素子のオン／オフ動作を停止する。磁気飽和に至る可能性が高く、第２のスイッチング素子のデューティ比（オン期間）を調整してもスイッチング動作を継続すれば、磁気飽和状態に陥ると推定される場合には、スイッチング動作を停止する。これにより、正極性のみ検知可能な電流センサであっても、トランスの励磁をリセットする場合の負側の励磁電流による磁気飽和を未然に防止することができる。 The control unit stops the on / off operation of the first switching element and the second switching element. If there is a high possibility of magnetic saturation and switching operation is continued even if the duty ratio (on period) of the second switching element is adjusted, the switching operation is stopped if it is estimated that the magnetic saturation will occur. Do. As a result, even in the case of a current sensor capable of detecting only the positive polarity, it is possible to prevent in advance the magnetic saturation due to the negative excitation current in the case of resetting the excitation of the transformer.
　本実施の形態に係る電源装置において、前記推定部は、一のスイッチング周期で前記第２のスイッチング素子のオフ時点から前記所定時間が経過した時点にて前記電流取得部で取得した第１電流と、第３閾値とに基づくとともに、前記第１電流と、前記一のスイッチング周期よりも前のスイッチング周期で前記第２のスイッチング素子のオフ時点から前記所定時間が経過した時点にて前記電流取得部で取得した第２電流との比と、第４閾値とに基づいて、前記トランスが磁気飽和に至ると推定し、前記制御部は、前記第２のスイッチング素子のオン期間が短くなるようにオン／オフ動作を制御する。 In the power supply device according to the present embodiment, the estimation unit is configured to receive the first current acquired by the current acquisition unit when the predetermined time has elapsed from the time when the second switching element is turned off in one switching cycle. And the third current threshold, and the current acquisition unit at the time when the predetermined time has elapsed from the time when the second switching element is turned off in a switching cycle earlier than the first current and the one switching cycle. On the basis of the ratio to the second current acquired in step 4 and the fourth threshold value, the transformer is estimated to reach magnetic saturation, and the control unit turns on so that the on period of the second switching element becomes short. Control / off operation.
　推定部は、一のスイッチング周期で第２のスイッチング素子のオフ時点から所定時間が経過した時点にて取得した第１電流と、第３閾値とに基づくとともに、当該一のスイッチング周期での第１電流と、当該一のスイッチング周期よりも前のスイッチング周期で第２のスイッチング素子のオフ時点から所定時間が経過した時点にて取得した第２電流との比と、第４閾値とに基づいて、トランスが磁気飽和に至ると推定する。 The estimation unit is based on the first current and the third threshold acquired when a predetermined time has elapsed from the off time point of the second switching element in one switching cycle, and the first in the one switching cycle Based on a fourth threshold and a ratio of a current to a second current obtained when a predetermined time has elapsed from the time when the second switching element is turned off in a switching cycle earlier than the one switching cycle, and It is estimated that the transformer leads to magnetic saturation.
　制御部は、第２のスイッチング素子のオン期間が短くなるようにオン／オフ動作を制御する。トランスの一次巻線の電流（すなわち、共振電流）が、スイッチング周期の経過に伴って増加し磁気飽和に至る可能性があるものの、第２のスイッチング素子のデューティ比（オン期間）を調整すれば、磁気飽和状態に陥ることを回避できる場合には、スイッチング動作を停止せずに、第２のスイッチング素子のオン期間が短くなるようにオン／オフ動作を制御する。これにより、磁気飽和を未然に防止することができる。 The control unit controls the on / off operation such that the on period of the second switching element becomes short. Although the current (that is, the resonant current) of the primary winding of the transformer may increase with the passage of the switching period and lead to magnetic saturation, if the duty ratio (on period) of the second switching element is adjusted If the magnetic saturation state can be avoided, the on / off operation is controlled so that the on period of the second switching element becomes short without stopping the switching operation. Thereby, magnetic saturation can be prevented in advance.
　本実施の形態に係る電源装置は、前記所定時間は、前記トランスの漏れインダクタンス及び前記第１のキャパシタのキャパシタンスに依拠する共振周期の１／４の時間及び該時間の近傍時間を含む。 In the power supply device according to the present embodiment, the predetermined time includes a time of 1⁄4 of a resonance period relying on the leakage inductance of the transformer and the capacitance of the first capacitor and a time near the time.
　所定時間は、トランスの漏れインダクタンス及び第１のキャパシタのキャパシタンスに依拠する共振周期Ｔｄの１／４の時間及び当該時間の近傍時間を含む。共振電流は、正弦波状をなすので、共振電流の負側の振幅のピークから正側の振幅のピークに至る時間は、共振周期Ｔｄの４分の１に相当する。また、共振電流の負側の振幅のピークは、正側の振幅のピークに等しいと考えられる。そこで、共振電流の負側の振幅のピークの時点からＴｄ／４の時点での電流を検出すれば、負側の振幅のピーク値を推定することができる。なお、共振電流の負側の振幅がピークとなる時点は、第１のスイッチング素子がオフ状態であって、第２のスイッチング素子のオフ時点とすることができる。近傍時間は、例えば、トランスの漏れインダクタンス及び第１のキャパシタのキャパシタンスのばらつきを考慮して、共振周期のばらつきを考慮した時間とすることができる。 The predetermined time includes a time of 1⁄4 of the resonance period Td relying on the leakage inductance of the transformer and the capacitance of the first capacitor and a time close to the time. Since the resonant current is sinusoidal, the time from the peak of the negative amplitude of the resonant current to the peak of the positive amplitude corresponds to a quarter of the resonance period Td. Also, the peak of the negative amplitude of the resonant current is considered to be equal to the peak of the positive amplitude. Therefore, the peak value of the negative amplitude can be estimated by detecting the current at Td / 4 from the peak of the negative amplitude of the resonant current. The point at which the amplitude on the negative side of the resonance current peaks is at the point when the first switching element is in the off state and the second switching element is off. The near time may be, for example, a time in which the variation of the resonance period is considered in consideration of the variation of the leakage inductance of the transformer and the capacitance of the first capacitor.
　これにより、正極性のみ検知可能な電流センサであっても、トランスの励磁をリセットする場合の負側の励磁電流による磁気飽和を未然に防止することができる。また、負極性の電流を検知可能な電流センサは、正極性に変換するための回路、増幅回路などを具備する必要があり一般的に高価となる。正極性のみ検知可能な電流センサを使用することができるので、コストダウンにも寄与する。 As a result, even in the case of a current sensor capable of detecting only the positive polarity, it is possible to prevent in advance the magnetic saturation due to the negative excitation current in the case of resetting the excitation of the transformer. In addition, a current sensor capable of detecting a negative current needs to include a circuit for converting the current to a positive polarity, an amplification circuit, and the like, which is generally expensive. Since a current sensor capable of detecting only positive polarity can be used, it contributes to cost reduction.
　本実施の形態に係る電源装置は、トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、前記一次巻線に並列に接続された第２のスイッチング素子と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置であって、前記トランスの電流を取得する電流取得部と、前記第２のスイッチング素子のオン時点又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて前記電流取得部で取得した電流に基づいて、前記トランスが磁気飽和に至るか否かを推定する推定部とを備え、前記制御部は、前記推定部の推定結果に基づいて前記第２のスイッチング素子のオン／オフ動作を制御する。 A power supply device according to the present embodiment includes: a transformer; a first switching element connected in series to a primary winding of the transformer; a second switching element connected in parallel to the primary winding; A power supply device comprising: a control unit that turns on / off a first switching element and a second switching element in a predetermined switching cycle, and a current acquisition unit that acquires a current of the transformer; and the second switching An estimation unit that estimates whether or not the transformer reaches magnetic saturation based on the current acquired by the current acquisition unit when a predetermined time has elapsed from the time when the element is turned on or when the second switching element is turned off And the control unit controls the on / off operation of the second switching element based on the estimation result of the estimation unit.
　本実施の形態に係る電源装置の制御方法は、トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、前記一次巻線に並列に接続された第２のスイッチング素子と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置の制御方法であって、前記トランスの電流を取得し、前記第２のスイッチング素子のオン時点又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて、取得された電流に基づいて、前記トランスが磁気飽和に至るか否かを推定し、前記制御部は、推定結果に基づいて前記第２のスイッチング素子のオン／オフ動作を制御する。 A control method of a power supply device according to the present embodiment includes a transformer, a first switching element connected in series to a primary winding of the transformer, and a second switching element connected in parallel to the primary winding. And a control unit configured to turn on / off the first switching element and the second switching element in a predetermined switching cycle, and obtaining a current of the transformer, At the time when a predetermined time has elapsed from the time when the switching element is turned on or the time when the second switching element is turned off, it is estimated whether or not the transformer reaches magnetic saturation based on the acquired current, and the control The unit controls the on / off operation of the second switching element based on the estimation result.
　電流取得部は、トランスの電流を取得する。 The current acquisition unit acquires the current of the transformer.
　推定部は、第２のスイッチング素子のオン時点にて取得した電流に基づいて、トランスが磁気飽和に至るか否かを推定する。また、推定部は、第２のスイッチング素子のオフ時点から所定時間が経過した時点にて取得した電流に基づいて、トランスが磁気飽和に至るか否かを推定する。なお、磁気飽和に至ると推定するとは、まだ磁気飽和に至っていない状態での推定である。 The estimation unit estimates whether or not the transformer reaches magnetic saturation based on the current acquired at the on time of the second switching element. Further, the estimation unit estimates whether or not the transformer reaches magnetic saturation based on the current acquired when a predetermined time has elapsed from the time when the second switching element is turned off. The assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached.
　第２スイッチング素子がオフ状態（期間Ｄ１と称する）では、トランスの一次巻線には入力側の電圧が印加され、トランスの一次巻線には、負荷電流及び励磁電流の合計が流れる。 When the second switching element is in the OFF state (referred to as a period D1), a voltage on the input side is applied to the primary winding of the transformer, and a total of load current and excitation current flows through the primary winding of the transformer.
　第１のスイッチング素子がオフとなり、第１のスイッチング素子及び第２スイッチング素子の両者がオフ状態（期間Ｄ２と称する）では、励磁電流は一定値に維持されるが負荷電流は減少する。 When the first switching element is turned off and both the first switching element and the second switching element are turned off (referred to as period D2), the excitation current is maintained at a constant value but the load current is decreased.
　第２のスイッチング素子のオン時点（期間Ｄ２の終了時点、期間Ｄ３の開始時点）では、トランスの一次巻線に流れる負荷電流は０となり励磁電流だけになる。そこで、第２のスイッチング素子のオン時点にて取得した電流は励磁電流だけとなり、負荷電流の影響を除外してトランスの磁気飽和の可能性を正確に推定することができる。 At the on time of the second switching element (end time of period D2, start time of period D3), the load current flowing through the primary winding of the transformer becomes 0 and becomes only the excitation current. Therefore, the current acquired at the on time of the second switching element is only the excitation current, and the influence of the load current can be excluded to accurately estimate the possibility of magnetic saturation of the transformer.
　第２のスイッチング素子がオン状態（期間Ｄ３と称する）では、トランスの励磁電流は減少する。 When the second switching element is in the on state (referred to as a period D3), the excitation current of the transformer decreases.
　第２のスイッチング素子がオフとなり、第１のスイッチング素子及び第２スイッチング素子の両者がオフ状態（期間Ｄ４と称する）では、トランスの漏れインダクタンス及び第１のスイッチング素子の両端に存在するキャパシタ（浮遊容量も含む）に依拠する共振が発生し、トランスの一次巻線には共振電流が流れる。磁気飽和に至る予兆として磁束バランスが崩れると共振電流の振幅が増加するので、第２のスイッチング素子のオフ時点から所定時間が経過した時点（例えば、共振中の所要の時点）にて取得した電流（すなわち共振電流）に基づいて、トランスの磁気飽和の可能性を正確に推定することができる。 When the second switching element is turned off and both the first switching element and the second switching element are turned off (referred to as period D4), the leakage inductance of the transformer and the capacitors (floating on both ends of the first switching element) The resonance (which also includes the capacitance) occurs, and a resonant current flows in the primary winding of the transformer. Since the amplitude of the resonant current increases when the magnetic flux balance breaks down as a sign of reaching magnetic saturation, the current acquired when a predetermined time has elapsed from the time when the second switching element is off (for example, the required time during resonance) Based on (i.e., the resonant current), the possibility of magnetic saturation of the transformer can be accurately estimated.
　また、共振電流は、電流０を間にして正側と負側の両方に共振するので、共振電流の正側の振幅を検出すれば、共振電流の負側の振幅を推定することができる。従って、正極性のみ検知可能な電流センサを用いても、トランスの負側の励磁電流による磁気飽和を推定することができる。 In addition, since the resonance current resonates on both the positive side and the negative side with current 0 in between, if the amplitude on the positive side of the resonance current is detected, the amplitude on the negative side of the resonance current can be estimated. Therefore, magnetic saturation due to the excitation current on the negative side of the transformer can be estimated even if a current sensor capable of detecting only the positive polarity is used.
　制御部は、推定部の推定結果に基づいて第２のスイッチング素子のオン／オフ動作を制御する。磁気飽和となる前に第２のスイッチング素子のオン／オフ動作を制御することができる。これにより、トランスの磁気飽和を未然に防止することができる。 The control unit controls the on / off operation of the second switching element based on the estimation result of the estimation unit. The on / off operation of the second switching element can be controlled before the magnetic saturation occurs. Thereby, magnetic saturation of the transformer can be prevented in advance.
［本願開示の実施形態の詳細］
　以下、本開示の実施の形態を図面に基づいて説明する。図１は本実施の形態の電源装置１００の回路構成の一例を示す説明図である。本実施の形態の電源装置１００は、入力側の端子Ａ及びＢ、出力側の端子Ｃ及びＤを備え、入力側の端子Ａ及びＢには、直流電源（不図示）が接続され、出力側の端子Ｃ及びＤには負荷が接続される。電源装置１００は、例えば、降圧変換装置である。 [Details of the embodiment of the present disclosure]
Hereinafter, embodiments of the present disclosure will be described based on the drawings. FIG. 1 is an explanatory view showing an example of a circuit configuration of a power supply device 100 according to the present embodiment. Power supply apparatus 100 of the present embodiment includes terminals A and B on the input side and terminals C and D on the output side, and a DC power supply (not shown) is connected to terminals A and B on the input side. A load is connected to terminals C and D of The power supply device 100 is, for example, a step-down conversion device.
　電源装置１００は、トランス３０、第１のスイッチング素子としてのＭＯＳＦＥＴ（Metal Oxide Semiconductor Field Effect Transistor、以下、「ＦＥＴ」と称する）１１、第１のキャパシタとしてのキャパシタ２１、第２のスイッチング素子としてのＦＥＴ１２、第２のキャパシタとしてのキャパシタ２２、整流回路としてのダイオード４１、４２、キャパシタ２３、インダクタ６１（出力側のチョークコイル）、及びＦＥＴ１１、ＦＥＴ１２を所定のスイッチング周期でオン／オフ動作させる制御部５０などを備える。ＦＥＴ１１、ＦＥＴ１２は、それぞれボディダイオードを有する。 The power supply device 100 includes a transformer 30, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor, hereinafter referred to as "FET") 11 as a first switching element, a capacitor 21 as a first capacitor, and a second switching element. Control unit for turning on / off the FET 12, the capacitor 22 as the second capacitor, the diodes 41 and 42 as the rectifier circuit, the capacitor 23, the inductor 61 (choke coil on the output side), and the FET 11 and FET 12 in a predetermined switching cycle And 50 etc. The FETs 11 and 12 each have a body diode.
　端子Ａには、トランス３０の一次巻線３１の一端が接続されている。一次巻線３１の他端には、ＦＥＴ１１のドレインが接続されている。ＦＥＴ１１のソースは、端子Ｂに接続されている。ＦＥＴ１１のドレイン・ソース間には、キャパシタ２１（共振用のキャパシタ）が接続されている。トランス３０の一次巻線３１に直列にカレントトランス７１を接続している。 One end of a primary winding 31 of the transformer 30 is connected to the terminal A. The drain of the FET 11 is connected to the other end of the primary winding 31. The source of the FET 11 is connected to the terminal B. A capacitor 21 (resonance capacitor) is connected between the drain and source of the FET 11. A current transformer 71 is connected in series to the primary winding 31 of the transformer 30.
　カレントトランス７１は、トランス３０の一次巻線３１に流れる電流を検出し、検出した電流を制御部５０へ出力する。 The current transformer 71 detects the current flowing through the primary winding 31 of the transformer 30, and outputs the detected current to the control unit 50.
　一次巻線３１の両端には、ＦＥＴ１２とキャパシタ２２との直列回路が接続されている。ＦＥＴ１２とキャパシタ２２との直列回路は、アクティブクランプ回路を構成する。 A series circuit of the FET 12 and the capacitor 22 is connected to both ends of the primary winding 31. A series circuit of the FET 12 and the capacitor 22 constitutes an active clamp circuit.
　図１の例では、一次巻線３１の一端にキャパシタ２２の一端が接続され、キャパシタ２２の他端にはＦＥＴ１２のドレインが接続されている。ＦＥＴ１２のソースは、一次巻線３１の他端に接続されている。 In the example of FIG. 1, one end of the capacitor 22 is connected to one end of the primary winding 31, and the drain of the FET 12 is connected to the other end of the capacitor 22. The source of the FET 12 is connected to the other end of the primary winding 31.
　トランス３０の二次巻線３２の一端にはダイオード４１のカソードが接続され、ダイオード４１のアノードは端子Ｄ（接地レベル）に接続されている。二次巻線３２の他端には、ダイオード４２のカソード及びインダクタ６１の一端が接続されている。ダイオード４２のアノードは、ダイオード４１のアノードに接続されている。なお、図１の例では、ダイオード４１、ダイオード４２それぞれのアノード同士が接続された構成となっているが、これに限定されるものではなく、ダイオード４１、ダイオード４２それぞれのカソード同士が接続された構成にしてもよい。 The cathode of the diode 41 is connected to one end of the secondary winding 32 of the transformer 30, and the anode of the diode 41 is connected to the terminal D (ground level). The other end of the secondary winding 32 is connected to the cathode of the diode 42 and one end of the inductor 61. The anode of the diode 42 is connected to the anode of the diode 41. In the example of FIG. 1, although the anodes of the diode 41 and the diode 42 are connected to each other, the present invention is not limited to this. The cathodes of the diode 41 and the diode 42 are connected to each other It may be configured.
　インダクタ６１の他端は端子Ｃに接続されている。端子Ｃ及びＤ間にはキャパシタ２３が接続されている。制御部５０は、ＦＥＴ１１、ＦＥＴ１２のゲートへゲート電圧を出力する。 The other end of the inductor 61 is connected to the terminal C. A capacitor 23 is connected between the terminals C and D. The control unit 50 outputs a gate voltage to the gates of the FETs 11 and 12.
　制御部５０は、電流取得部５１、推定部５２、記憶部５３などを備える。 The control unit 50 includes a current acquisition unit 51, an estimation unit 52, a storage unit 53, and the like.
　電流取得部５１は、トランス３０の電流を取得する。具体的には、電流取得部５１は、カレントトランス７１で検出されたトランス３０の電流を取得する。電流取得部５１は、正極性及び負極性の両方の電流を取得することができる構成でもよいが、本実施の形態では正極性のみ検知可能な構成として説明する。 The current acquisition unit 51 acquires the current of the transformer 30. Specifically, the current acquisition unit 51 acquires the current of the transformer 30 detected by the current transformer 71. The current acquisition unit 51 may be configured to be able to acquire both positive and negative currents, but in the present embodiment, only the positive polarity can be detected.
　推定部５２は、電流取得部５１で取得した電流に基づいて、トランス３０が磁気飽和に至るか否かを推定する。なお、磁気飽和に至ると推定するとは、まだ磁気飽和に至っていない状態での推定である。磁気飽和の推定方法の詳細は後述する。 The estimation unit 52 estimates, based on the current acquired by the current acquisition unit 51, whether or not the transformer 30 reaches magnetic saturation. The assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached. Details of the method of estimating the magnetic saturation will be described later.
　記憶部５３は、電流取得部５１で取得した電流、ＦＥＴ１１、ＦＥＴ１２のスイッチング動作時のデューティ比（オン期間の長さ）などの情報を記憶する。 The storage unit 53 stores information such as the current acquired by the current acquisition unit 51 and the duty ratio (the length of the on period) during the switching operation of the FET 11 and the FET 12.
　次に、本実施の形態の電源装置１００の動作について説明する。 Next, the operation of the power supply device 100 according to the present embodiment will be described.
　図２は本実施の形態の電源装置１００の各部の波形の一例を示すタイムチャートである。図２では、上から、ＦＥＴ１１のゲート電圧、ＦＥＴ１２のゲート電圧、トランス３０の電流（以下、トランス電流とも称する）、トランス３０の励磁電流（以下、励磁電流とも称する）の各波形を模式的に示す。便宜上各部の波形を模式的に図示するので、実際の各部の波形は異なる場合がある。 FIG. 2 is a time chart which shows an example of the waveform of each part of the power supply device 100 of this Embodiment. In FIG. 2, the waveforms of the gate voltage of the FET 11, the gate voltage of the FET 12, the current of the transformer 30 (hereinafter also referred to as transformer current), and the excitation current of the transformer 30 (hereinafter also referred to as excitation current) are schematically shown from the top Show. Because the waveforms of the respective parts are schematically illustrated for the sake of convenience, the actual waveforms of the respective parts may be different.
　図２に示すように、周期Ｔを期間Ｄ１、Ｄ２、Ｄ３及びＤ４の４つの期間に区分する。期間Ｄ１は、ＦＥＴ１１のオン期間であり、ＦＥＴ１１は、所定のデューティ比（Ｄ１／Ｔ）でオン／オフを繰り返す。また、期間Ｄ３は、ＦＥＴ１２のオン期間であり、ＦＥＴ１２は、所定のデューティ比（Ｄ３／Ｔ）でオン／オフを繰り返す。期間Ｄ２、Ｄ４は、ＦＥＴ１１及びＦＥＴ１２の両方がオフとなる期間である。次に、各期間Ｄ１～Ｄ４における電源装置１００の動作状態について順に説明する。 As shown in FIG. 2, the period T is divided into four periods D1, D2, D3 and D4. A period D1 is an on period of the FET 11, and the FET 11 repeats on / off at a predetermined duty ratio (D1 / T). Further, a period D3 is an on period of the FET 12, and the FET 12 repeats on / off at a predetermined duty ratio (D3 / T). Periods D2 and D4 are periods in which both the FET 11 and the FET 12 are turned off. Next, the operating state of the power supply device 100 in each of the periods D1 to D4 will be described in order.
　図３は本実施の形態の電源装置１００の期間Ｄ１での動作状態の一例を示す説明図である。図２に示すように、期間Ｄ１においては、制御部５０の制御により、ＦＥＴ１１はオン状態であり、ＦＥＴ１２はオフ状態である。期間Ｄ１では、トランス３０の一次巻線３１には、入力側の電源電圧が印加され、一次巻線３１の電圧は正となる。二次巻線３２の電圧も正となり、ダイオード４１が導通して負荷に負荷電流が流れる。トランス３０の一次巻線３１には、負荷電流及び励磁電流の合計が流れる。図２に示すように、トランス電流（負荷電流＋励磁電流）及び励磁電流は直線的に増加する。この場合、励磁電流の時間的変化量はトランス電流の時間的変化量に相当する。図３中、符号Ｌｍはトランス３０の励磁インダクタンスを表し、Ｌｓは漏れインダクタンスを表す。なお、便宜上、図３において、一次巻線３１及び二次巻線３２それぞれの下端に対して上端の電位が高い場合を正の電圧とする。 FIG. 3 is an explanatory view showing an example of an operation state of the power supply device 100 of the present embodiment in the period D1. As shown in FIG. 2, in the period D1, under the control of the control unit 50, the FET 11 is in the on state, and the FET 12 is in the off state. In period D1, the power supply voltage on the input side is applied to the primary winding 31 of the transformer 30, and the voltage of the primary winding 31 becomes positive. The voltage of the secondary winding 32 also becomes positive, and the diode 41 conducts and a load current flows in the load. A total of load current and excitation current flows through the primary winding 31 of the transformer 30. As shown in FIG. 2, the transformer current (load current + excitation current) and the excitation current increase linearly. In this case, the temporal variation of the excitation current corresponds to the temporal variation of the transformer current. In FIG. 3, the symbol Lm represents the excitation inductance of the transformer 30, and Ls represents the leakage inductance. For convenience, in FIG. 3, a case where the potential at the upper end is higher than the lower end of each of the primary winding 31 and the secondary winding 32 is referred to as a positive voltage.
　なお、トランス３０の一次側と二次側それぞれに流れる負荷電流による磁束はお互いに打消し合うのに対し、励磁電流は磁束を作るので、トランス３０が磁気飽和するか否かの要因の一つは励磁電流となる。 Note that while the magnetic fluxes due to the load currents flowing to the primary side and the secondary side of the transformer 30 cancel each other, the excitation current produces a magnetic flux, so one of the factors as to whether the transformer 30 is magnetically saturated or not Is the excitation current.
　図４は本実施の形態の電源装置１００の期間Ｄ２での動作状態の一例を示す説明図である。期間Ｄ２では、ＦＥＴ１１及びＦＥＴ１２の両者はオフ状態である。期間Ｄ２の開始時点で、ＦＥＴ１１をオンからオフにすることにより、キャパシタ２１が充電され、励磁電流が維持される。なお、キャパシタ２１が共振用のキャパシタであることを表すため、キャパシタ２１のキャパシタンスをＣｓとする。キャパシタ２１の充電に伴ってトランス３０（一次巻線３１及び二次巻線３２）の電圧は減少し、負荷電流は減少する。トランス３０の電圧が減少し、負になると、ダイオード４１は逆バイアスとなり、非導通となる。ダイオード４１に流れていた負荷電流はダイオード４２を介して流れるようになる。 FIG. 4 is an explanatory view showing an example of an operation state of the power supply device 100 of the present embodiment in the period D2. In the period D2, both the FET 11 and the FET 12 are in the off state. At the start of the period D2, by turning off the FET 11, the capacitor 21 is charged and the excitation current is maintained. In addition, in order to indicate that the capacitor 21 is a capacitor for resonance, the capacitance of the capacitor 21 is Cs. As the capacitor 21 is charged, the voltage of the transformer 30 (primary winding 31 and secondary winding 32) decreases, and the load current decreases. When the voltage of the transformer 30 decreases and becomes negative, the diode 41 becomes reverse biased and becomes nonconductive. The load current flowing in the diode 41 flows through the diode 42.
　期間Ｄ２の終了時点、すなわち期間Ｄ３の開始時点では、減少した負荷電流が、トランス３０の一次側から見かけ上見えなくなり、トランス３０の一次側から見た負荷電流が０となる。これにより、ＦＥＴ１２がオフからオンする時点で、電流取得部５１が取得するトランス電流は励磁電流のみとなり、負荷電流の影響を除去することができる。 At the end of period D2, that is, at the start of period D3, the reduced load current is apparently invisible from the primary side of transformer 30, and the load current viewed from the primary side of transformer 30 is zero. As a result, when the FET 12 is turned on from off, the transformer current acquired by the current acquisition unit 51 is only the excitation current, and the influence of the load current can be removed.
　図５は本実施の形態の電源装置１００の期間Ｄ３での動作状態の一例を示す説明図である。期間Ｄ３では、ＦＥＴ１２はオン状態であり、ＦＥＴ１１はオフ状態のままである。期間Ｄ３の開始時点で、ＦＥＴ１２がオフからオンになるので、トランス３０には、キャパシタ２２の電圧が逆方向（負の電圧の方向）に印加され、トランス３０の励磁電流は減少し、トランス３０の励磁をリセットする状態に移行する。そして、トランス３０の励磁電流が逆転し（負になる、電流方向が逆になる）、キャパシタ２２に蓄えられたエネルギーが放出され、トランス３０の漏れインダクタンスＬｓにエネルギーが蓄積される。 FIG. 5 is an explanatory view showing an example of an operation state of the power supply device 100 of the present embodiment in the period D3. In the period D3, the FET 12 is in the on state, and the FET 11 is in the off state. At the start of period D3, the FET 12 turns from off to on, so the voltage of the capacitor 22 is applied to the transformer 30 in the reverse direction (direction of negative voltage), and the exciting current of the transformer 30 decreases. Move to the state to reset the excitation of. Then, the excitation current of the transformer 30 is reversed (becomes negative, the current direction is reversed), the energy stored in the capacitor 22 is released, and the energy is stored in the leakage inductance Ls of the transformer 30.
　図６は本実施の形態の電源装置１００の期間Ｄ４での動作状態の一例を示す説明図である。期間Ｄ４では、ＦＥＴ１２及びＦＥＴ１１の両方はオフ状態である。期間Ｄ４では、トランス３０（より具体的には、漏れインダクタンスＬｓ）及びキャパシタンスＣｓによる共振が発生する。ダイオード４２には、負荷に流れる負荷電流Ｉｌ（図中、実線で示す）、トランス３０の励磁電流Ｉｍ（図中、破線で示す）、トランス３０（トランス３０の漏れインダクタンスＬｓ）及びキャパシタンスＣｓの共振による共振電流Ｉｒ（図中、一点鎖線で示す）が流れる。すなわち、トランス３０に流れる電流は共振する。 FIG. 6 is an explanatory view showing an example of the operation state of the power supply device 100 of the present embodiment in the period D4. In the period D4, both the FET 12 and the FET 11 are in the off state. In the period D4, resonance occurs due to the transformer 30 (more specifically, the leakage inductance Ls) and the capacitance Cs. The diode 42 includes a load current Il (indicated by a solid line in the figure) flowing to the load, an excitation current Im of the transformer 30 (indicated by a dashed line in the figure), a resonance of the transformer 30 (leakage inductance Ls of the transformer 30) and a capacitance Cs. A resonant current Ir (indicated by a dot-and-dash line in the figure) flows. That is, the current flowing through the transformer 30 resonates.
　負荷電流Ｉｌは、ダイオード４２、インダクタ６１、負荷の閉ループを流れる。負荷電流Ｉｌは、例えば、インダクタ６１のインダクタンスを比較的大きくすることにより、一定の値となる。 The load current Il flows through the diode 42, the inductor 61, and the closed loop of the load. The load current I1 has a constant value, for example, by relatively increasing the inductance of the inductor 61.
　励磁電流Ｉｍは、トランス３０、ダイオード４２、４１の閉ループを流れる。期間Ｄ４において、励磁インダクタンスＬｍに印加される電圧がほぼゼロであるため、励磁電流Ｉｍは維持される。 The excitation current Im flows in the closed loop of the transformer 30 and the diodes 42 and 41. Since the voltage applied to the excitation inductance Lm is substantially zero in the period D4, the excitation current Im is maintained.
　トランス３０の漏れインダクタンスＬｓ及びキャパシタンスＣｓに依拠する共振は、期間Ｄ４の開始時点から始まり、共振電流Ｉｒは、正弦波状をなし、キャパシタＣ２１、トランス３０を流れる。 The resonance based on the leakage inductance Ls and the capacitance Cs of the transformer 30 starts from the start of the period D4, and the resonance current Ir is sinusoidal and flows through the capacitor C21 and the transformer 30.
　次に、トランス３０が磁気飽和に至るか否かの推定方法について説明する。まず、トランス３０の励磁の際の正側の励磁電流による磁気飽和について説明する。なお、トランス３０の飽和磁束密度をＢｍａｘとし、コアの断面積をＡとし、励磁インダクタンスをＬｍとし、励磁電流をＩｍとし、トランス３０の一次巻線３１の巻線数をｎとし、トランス３０の磁束をΦとすると、磁束Φは、Φ＝Ｉｍ×Ｌｍ／ｎで表すことができ、磁気飽和する条件は、｜Φ｜／Ａ≧Ｂｍａｘという式で表すことができる。なお、磁束Φを求めるための励磁インダクタンスＬｍは、トランス３０の巻線比を含む値であるため、キャンセルするため巻線数ｎで除算している。 Next, a method of estimating whether or not the transformer 30 reaches magnetic saturation will be described. First, magnetic saturation due to the positive side excitation current when the transformer 30 is excited will be described. The saturation magnetic flux density of the transformer 30 is Bmax, the cross-sectional area of the core is A, the excitation inductance is Lm, the excitation current is Im, and the number of primary windings 31 of the transformer 30 is n. Assuming that the magnetic flux is Φ, the magnetic flux Φ can be expressed by == Im × Lm / n, and the condition for magnetically saturating can be expressed by the formula | Φ | / A ≧ Bmax. Since the excitation inductance Lm for obtaining the magnetic flux 含 む is a value including the winding ratio of the transformer 30, it is divided by the number n of windings for canceling.
　図７は本実施の形態の電源装置１００によるトランス３０の磁気飽和の推定方法の第１例を示す説明図である。上から、ＦＥＴ１１のゲート電圧、ＦＥＴ１２のゲート電圧、トランス電流を示す。 FIG. 7 is an explanatory view showing a first example of a method of estimating the magnetic saturation of the transformer 30 by the power supply device 100 of the present embodiment. From the top, the gate voltage of the FET 11, the gate voltage of the FET 12, and the transformer current are shown.
　時点ｔ１の期間Ｄ１の開始時点でＦＥＴ１１がオフからオンとなり、期間Ｄ１では、ＦＥＴ１１がオン状態であって、ＦＥＴ１２がオフ状態である。トランス３０の一次巻線３１には入力側の電圧が印加され、トランス３９の一次巻線３１には、負荷電流及び励磁電流の合計が流れる。 At the start of period D1 at time t1, FET 11 turns from off to on, and in period D1, FET 11 is on and FET 12 is off. The voltage on the input side is applied to the primary winding 31 of the transformer 30, and the sum of the load current and the excitation current flows through the primary winding 31 of the transformer 39.
　時点ｔ２でＦＥＴ１１がオンからオフとなり、期間Ｄ２では、ＦＥＴ１１及びＦＥＴ１２の両者がオフ状態となる。期間Ｄ２では、励磁電流は一定値に維持されるが負荷電流は急激に減少する。 At time t2, the FET 11 turns from on to off, and in a period D2, both the FET 11 and the FET 12 turn off. In the period D2, the excitation current is maintained at a constant value, but the load current rapidly decreases.
　時点ｔ３でＦＥＴ１２がオフからオンとなり、期間Ｄ３の開始時点では、トランス３０の一次巻線３１に流れる負荷電流は０となり励磁電流だけになる。すなわち、ＦＥＴ１１がオフ状態であって、ＦＥＴ１２のオン時点にて取得した電流は励磁電流だけとなり、負荷電流の影響を除外することができ、トランス３０の磁気飽和の可能性を正確に推定することができる。 At time t3, the FET 12 turns from off to on, and at the start of the period D3, the load current flowing through the primary winding 31 of the transformer 30 becomes 0 and becomes only the excitation current. That is, the FET 11 is in the OFF state, and the current acquired at the ON time of the FET 12 is only the excitation current, and the influence of the load current can be excluded, and the possibility of magnetic saturation of the transformer 30 can be accurately estimated. Can.
　推定部５２は、ＦＥＴ１１がオフ状態であって、ＦＥＴ１２のオン時点にて取得した電流に基づいて、トランス３０が磁気飽和に至るか否かを推定する。なお、磁気飽和に至ると推定するとは、まだ磁気飽和に至っていない状態での推定である。制御部５０は、推定部５２の推定結果に基づいてＦＥＴ１１又はＦＥＴ１２のオン／オフ動作を制御する。磁気飽和となる前にＦＥＴ１１又はＦＥＴ１２のオン／オフ動作を制御することができる。これにより、トランス３０の磁気飽和を未然に防止することができる。 The estimation unit 52 estimates whether or not the transformer 30 reaches magnetic saturation based on the current obtained when the FET 11 is off and the FET 12 is on. The assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached. The control unit 50 controls the on / off operation of the FET 11 or the FET 12 based on the estimation result of the estimation unit 52. The on / off operation of the FET 11 or FET 12 can be controlled before magnetic saturation occurs. Thereby, magnetic saturation of the transformer 30 can be prevented in advance.
　より具体的には、推定部５２は、ＦＥＴ１１がオフ状態であって、ＦＥＴ１２のオン時点（時点ｔ３）にて取得した電流Ｉｍが第１閾値Ｉｔｈ１より大きい場合、トランス３０が磁気飽和に至ると推定する。 More specifically, when the FET 11 is off and the current Im acquired at the on time (time t3) of the FET 12 is larger than the first threshold Ith1, the estimation unit 52 determines that the transformer 30 has reached magnetic saturation. presume.
　制御部５０は、電流Ｉｍが第１閾値Ｉｔｈ１より大きい場合、ＦＥＴ１１及びＦＥＴ１２のオン／オフ動作を停止する。 The control unit 50 stops the on / off operation of the FET 11 and the FET 12 when the current Im is larger than the first threshold Ith1.
　磁気飽和に至る可能性が高く、ＦＥＴ１１のデューティ比（オン期間）を調整してもスイッチング動作を継続すれば、磁気飽和状態に陥ると推定される場合には、スイッチング動作を停止する。これにより、トランス３０を励磁する場合の正側の励磁電流による磁気飽和を未然に防止することができる。 If the possibility of reaching magnetic saturation is high and the switching operation is continued even if the duty ratio (on period) of the FET 11 is adjusted, the switching operation is stopped if it is estimated that the magnetic saturation state occurs. Thereby, it is possible to prevent in advance the magnetic saturation due to the positive side excitation current when the transformer 30 is excited.
　図８は本実施の形態の電源装置１００によるトランス３０の磁気飽和の推定方法の第２例を示す説明図である。上から、ＦＥＴ１１のゲート電圧、ＦＥＴ１２のゲート電圧、トランス電流を示す。図８において、時点ｔ１５から時点ｔ１９までが一のスイッチング周期であり、時点ｔ１１から時点ｔ１５までが当該一のスイッチング周期よりも１周期だけ前のスイッチング周期である。 FIG. 8 is an explanatory view showing a second example of the method of estimating the magnetic saturation of the transformer 30 by the power supply device 100 of the present embodiment. From the top, the gate voltage of the FET 11, the gate voltage of the FET 12, and the transformer current are shown. In FIG. 8, time t15 to time t19 is one switching cycle, and time t11 to time t15 is a switching cycle one cycle earlier than the one switching cycle.
　電流取得部５１が、一のスイッチング周期でＦＥＴ１１がオフ状態であって、ＦＥＴ１２のオン時点（時点ｔ１７）にて取得した電流（励磁電流）をＩｍ（ｎ）とする。また、電流取得部５１が、当該一のスイッチング周期よりも前のスイッチング周期でＦＥＴ１１がオフ状態であって、ＦＥＴ１２のオン時点（時点ｔ１３）にて取得した電流（励磁電流）をＩｍ（ｎ－１）とする。前述のとおり、時点ｔ１３、時点ｔ１７で取得したトランス電流は、負荷電流を含まず励磁電流だけとなる。 The current acquisition unit 51 sets the current (excitation current) acquired at the ON time point (time point t17) of the FET 12 to Im (n) when the FET 11 is off in one switching cycle. Further, the current (excitation current) acquired at the ON time point (time point t13) of the FET 12 when the current acquisition unit 51 is in the OFF state of the FET 11 in the switching cycle earlier than the one switching cycle is Im (n− 1) As described above, the transformer current acquired at time t13 and time t17 does not include the load current but is only the excitation current.
　図８に示す状態において、トランス３０の励磁インダクタンスをＬｍとし、ＦＥＴ１１がオン状態である期間Ｄ１（ｎ－１）における入力電圧をＶｉｎ（ｎ－１）とすると、Ｉｍ（ｎ）＝{Ｖｉｎ（ｎ－１）×Ｄ１（ｎ－１）}／Ｌｍという関係が成り立つ。ＦＥＴ１１のオン期間Ｄ１の変動率と電流Ｉｍの変動率が所定値以上乖離した場合は、トランス３０が磁気飽和に至る可能性があると推定することができる。すなわち、推定部５２は、電流Ｉｍ（ｎ）が第１閾値Ｉｔｈ１以下であって、{Ｉｍ（ｎ）／Ｉｍ（ｎ－１）}が{Ｄ１（ｎ－１）／Ｄ１（ｎ－２）}×Ｔｈ１より大きい場合、トランス３０が磁気飽和に至ると推定する。 Assuming that the excitation inductance of the transformer 30 is Lm and the input voltage during the period D1 (n-1) in which the FET 11 is on is Vin (n-1) in the state shown in FIG. 8, Im (n) = {Vin ( The following relationship holds: n-1) × D1 (n-1)} / Lm. If the fluctuation rate of the on period D1 of the FET 11 and the fluctuation rate of the current Im deviate by a predetermined value or more, it can be estimated that the transformer 30 may reach magnetic saturation. That is, in the estimation unit 52, the current Im (n) is equal to or less than the first threshold Ith1, and {Im (n) / Im (n-1)} is {D1 (n-1) / D1 (n-2). If it is larger than} × Th1, it is estimated that the transformer 30 reaches magnetic saturation.
　制御部５０は、電流Ｉｍ（ｎ）が第１閾値Ｉｔｈ１以下であって、{Ｉｍ（ｎ）／Ｉｍ（ｎ－１）}が{Ｄ１（ｎ－１）／Ｄ１（ｎ－２）}×Ｔｈ１より大きい場合、ＦＥＴ１１のオン期間が短くなるようにオン／オフ動作を制御する。 The control unit 50 determines that the current Im (n) is equal to or less than the first threshold Ith1 and {Im (n) / Im (n-1)} is {D1 (n-1) / D1 (n-2)} × If larger than Th1, the on / off operation is controlled so that the on period of the FET 11 becomes short.
　トランス３０の一次巻線３１の電流（すなわち、トランス３０の励磁電流）が、スイッチング周期の経過に伴って増加し磁気飽和に至る可能性があるものの、ＦＥＴ１１のデューティ比（オン期間）を調整すれば、磁気飽和状態に陥ることを回避できる場合には、スイッチング動作を停止せずに、ＦＥＴ１１のオン期間が短くなるようにオン／オフ動作を制御する。これにより、電源装置１００の動作を停止させることなく、磁気飽和を未然に防止することができる。 Although the current of the primary winding 31 of the transformer 30 (that is, the excitation current of the transformer 30) may increase with the passage of the switching period and lead to magnetic saturation, it is possible to adjust the duty ratio (on period) of the FET 11. For example, when it is possible to avoid the magnetic saturation state, the on / off operation is controlled so that the on period of the FET 11 becomes short without stopping the switching operation. As a result, magnetic saturation can be prevented in advance without stopping the operation of the power supply device 100.
　なお、磁気飽和の推定の際に、{Ｉｍ（ｎ）／Ｉｍ（ｎ－１）}が{Ｄ１（ｎ－１）／Ｄ１（ｎ－２）}×Ｔｈ１より大きいか否かを判定する構成に代えて、{Ｉｍ（ｎ）／Ｉｍ（ｎ－１）}がＴｈ１より大きいか否かを判定するようにしてもよい。しかし、ＦＥＴ１１のオン期間（Ｄ１）を長くすれば、正側の励磁電流は増加し、ＦＥＴ１１のオン期間（Ｄ１）を短くすれば、正側の励磁電流は減少するので、{Ｄ１（ｎ－１）／Ｄ１（ｎ－２）}を考慮することにより、ＦＥＴ１１のオン期間（Ｄ１）の変動による励磁電流の増減を相殺して、本来の要因（例えば、入力電圧の変動など）による磁気飽和の可能性の有無を推定することができる。 In addition, it is determined whether or not {Im (n) / Im (n-1)} is larger than {D1 (n-1) / D1 (n-2)} × Th1 at the time of magnetic saturation estimation. Alternatively, it may be determined whether {Im (n) / Im (n-1)} is larger than Th1. However, if the on period (D1) of the FET 11 is increased, the excitation current on the positive side increases, and if the on period (D1) of the FET 11 is shortened, the excitation current on the positive side decreases. 1) By taking account of / D1 (n-2)}, the increase and decrease of the excitation current due to the fluctuation of the on period (D1) of the FET 11 are offset, and the magnetic saturation due to the original factor (for example, the fluctuation of the input voltage etc.) It is possible to estimate the possibility of
　次に、トランス３０の励磁をリセットする際の負側の励磁電流による磁気飽和について説明する。 Next, magnetic saturation due to the negative excitation current when resetting the excitation of the transformer 30 will be described.
　図９は本実施の形態の電源装置１００によるトランス３０の磁気飽和の推定方法の第３例を示す説明図である。上から、ＦＥＴ１１のゲート電圧、ＦＥＴ１２のゲート電圧、トランス電流を示す。 FIG. 9 is an explanatory view showing a third example of the method of estimating the magnetic saturation of the transformer 30 by the power supply device 100 of the present embodiment. From the top, the gate voltage of the FET 11, the gate voltage of the FET 12, and the transformer current are shown.
　ＦＥＴ１１がオフ状態であって、ＦＥＴ１２がオン状態では（期間Ｄ３）では、トランス３０の励磁電流は減少し、トランス３０の励磁をリセットする状態に移行する。 When the FET 11 is in the OFF state and the FET 12 is in the ON state (period D3), the excitation current of the transformer 30 decreases, and the excitation of the transformer 30 is reset.
　時点ｔ４でＦＥＴ１２がオンからオフとなり、ＦＥＴ１１及びＦＥＴ１２の両者がオフ状態となる期間Ｄ４では、トランス３０の漏れインダクタンスＬｓ及びキャパシタ２１のキャパシタンスンスＣｓに依拠する共振が発生し、トランス３０の一次巻線３１には共振電流が流れる。 In a period D4 in which the FET 12 is turned on and off at time t4 and both the FET 11 and the FET 12 are turned off, resonance based on the leakage inductance Ls of the transformer 30 and the capacitance Cs of the capacitor 21 is generated. A resonant current flows in the line 31.
　磁気飽和に至る予兆として磁束バランスが崩れると共振電流の振幅が増加するので、期間Ｄ４の開始時点（時点ｔ４）から所定時間が経過した時点（例えば、共振中の所要の時点）にて取得した電流（すなわち共振電流）に基づいて、トランス３０の磁気飽和の可能性を正確に推定することができる。 The amplitude of the resonant current increases when the magnetic flux balance breaks down as a sign of reaching magnetic saturation, and thus acquired at a time (for example, a required time during resonance) when a predetermined time has elapsed from the start time of the period D4 (time t4). Based on the current (ie, the resonant current), the likelihood of magnetic saturation of the transformer 30 can be accurately estimated.
　また、共振電流は、電流０を間にして正側と負側の両方に共振するので、共振電流の正側の振幅を検出すれば、共振電流の負側の振幅を推定することができる。従って、正極性のみ検知可能な電流センサを用いても、トランス３０の励磁をリセットするときの負側の励磁電流による磁気飽和を推定することができる。 In addition, since the resonance current resonates on both the positive side and the negative side with current 0 in between, if the amplitude on the positive side of the resonance current is detected, the amplitude on the negative side of the resonance current can be estimated. Therefore, even if a current sensor capable of detecting only the positive polarity is used, magnetic saturation due to the negative excitation current when resetting the excitation of the transformer 30 can be estimated.
　推定部５２は、ＦＥＴ１１がオフ状態であって、ＦＥＴ１２のオフ時点から所定時間が経過した時点にて取得した電流に基づいて、トランス３０が磁気飽和に至るか否かを推定する。なお、磁気飽和に至ると推定するとは、まだ磁気飽和に至っていない状態での推定である。制御部５０は、推定部５２の推定結果に基づいてＦＥＴ１１又はＦＥＴ１２のオン／オフ動作を制御する。磁気飽和となる前にＦＥＴ１１又はＦＥＴ１２のオン／オフ動作を制御することができる。これにより、トランス３０の磁気飽和を未然に防止することができる。 The estimation unit 52 estimates whether or not the transformer 30 reaches magnetic saturation based on the current acquired when the FET 11 is off and a predetermined time has elapsed from the off time of the FET 12. The assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached. The control unit 50 controls the on / off operation of the FET 11 or the FET 12 based on the estimation result of the estimation unit 52. The on / off operation of the FET 11 or FET 12 can be controlled before magnetic saturation occurs. Thereby, magnetic saturation of the transformer 30 can be prevented in advance.
　より具体的には、推定部５２は、ＦＥＴ１２のオフ時点（時点ｔ４）から所定時間が経過した時点（例えば、共振周期Ｔｄの４分の１に相当する時間など）にて取得した電流Ｉｍ１が第３閾値Ｉｔｈ２より大きい場合、トランス３０が磁気飽和に至ると推定する。 More specifically, the estimation unit 52 determines that the current Im1 acquired at a time (for example, a time corresponding to a quarter of the resonance period Td) when a predetermined time has elapsed from the OFF time (time t4) of the FET 12 is When it is larger than the third threshold Ith2, it is estimated that the transformer 30 reaches magnetic saturation.
　制御部は、電流Ｉｍ１が第３閾値Ｉｔｈ２より大きい場合、ＦＥＴ１１及びＦＥＴ１２のオン／オフ動作を停止する。 The control unit stops the on / off operation of the FET 11 and the FET 12 when the current Im1 is larger than the third threshold Ith2.
　磁気飽和に至る可能性が高く、ＦＥＴ１２のデューティ比（オン期間）を調整してもスイッチング動作を継続すれば、磁気飽和状態に陥ると推定される場合には、スイッチング動作を停止する。これにより、負極性を検知することができない電流センサを用いても、トランス３０の励磁をリセットする場合の負側の励磁電流による磁気飽和を未然に防止することができる。 If the possibility of reaching magnetic saturation is high and the switching operation is continued even if the duty ratio (on period) of the FET 12 is adjusted, the switching operation is stopped if it is estimated that the magnetic saturation state occurs. Thereby, even when using a current sensor which can not detect the negative polarity, it is possible to prevent in advance the magnetic saturation due to the negative excitation current when the excitation of the transformer 30 is reset.
　前述の所定時間は、トランス３０の漏れインダクタンスＬｓ及びキャパシタ２１のキャパシタンスＣｓに依拠する共振周期Ｔｄの１／４の時間及び当該時間の近傍時間とすることができる。 The above-mentioned predetermined time can be a time of 1⁄4 of the resonance period Td depending on the leakage inductance Ls of the transformer 30 and the capacitance Cs of the capacitor 21 and a time near the time.
　図９に示すように、共振電流は、正弦波状をなすので、共振電流の負側の振幅のピークＩｍ２から正側の振幅のピークＩｍ１に至る時間は、共振周期Ｔｄの４分の１に相当する。また、共振電流の負側の振幅のピークＩｍ２は、正側の振幅のピークＩｍ１に等しいと考えられる。そこで、共振電流の負側の振幅のピークの時点からＴｄ／４の時点での電流Ｉｍ１を検出すれば、負側の振幅のピークＩｍ２を推定することができる。 As shown in FIG. 9, since the resonance current has a sine wave shape, the time from the peak Im2 of the negative amplitude of the resonance current to the peak Im1 of the positive amplitude corresponds to a quarter of the resonance period Td. Do. Also, it is considered that the peak Im2 of the negative side amplitude of the resonance current is equal to the peak Im1 of the positive side amplitude. Therefore, if the current Im1 at the point of Td / 4 from the point of the peak of the amplitude on the negative side of the resonance current is detected, it is possible to estimate the peak Im2 of the amplitude on the negative side.
　なお、共振電流の負側の振幅がピークとなる時点は、ＦＥＴ１１がオフ状態であって、ＦＥＴ１２のオフ時点（すなわち、期間Ｄ４の開始時点）とすることができる。また、近傍時間は、例えば、トランス３０の漏れインダクタンスＬｓ及びキャパシタ２１のキャパシタンスＣｓのばらつきを考慮して、共振周期Ｔｄのばらつきを考慮した時間とすることができる。 The point at which the amplitude on the negative side of the resonance current peaks is at the point when the FET 12 is off (that is, at the start of the period D4). Further, the vicinity time can be, for example, a time in consideration of the dispersion of the resonance period Td in consideration of the dispersion of the leakage inductance Ls of the transformer 30 and the capacitance Cs of the capacitor 21.
　上述の構成により、正極性のみ検知可能な電流センサであっても、トランス３０の励磁をリセットする場合の負側の励磁電流による磁気飽和を未然に防止することができる。また、負極性の電流を検知可能な電流センサは、正極性に変換するための回路、増幅回路などを具備する必要があり一般的に高価となる。正極性のみ検知可能な電流センサを使用することができるので、コストダウンにも寄与する。 With the above-described configuration, even in the case of a current sensor capable of detecting only the positive polarity, it is possible to prevent in advance the magnetic saturation due to the negative excitation current when the excitation of the transformer 30 is reset. In addition, a current sensor capable of detecting a negative current needs to include a circuit for converting the current to a positive polarity, an amplification circuit, and the like, which is generally expensive. Since a current sensor capable of detecting only positive polarity can be used, it contributes to cost reduction.
　図１０は本実施の形態の電源装置１００によるトランス３０の磁気飽和の推定方法の第４例を示す説明図である。電流取得部５１が、一のスイッチング周期でＦＥＴ１１がオフ状態であって、ＦＥＴ１２のオフ時点から所定時間が経過した時点（期間Ｄ４（ｎ）の開始時点から共振周期Ｔｄの４分の１に相当する時間が経過した時点）にて取得した電流（励磁電流）をＩｍ１（ｎ）とする。また、電流取得部５１が、当該一のスイッチング周期よりも前のスイッチング周期でＦＥＴ１１がオフ状態であって、ＦＥＴ１２のオフ時点から所定時間が経過した時点（期間Ｄ４（ｎ）の開始時点から共振周期Ｔｄの４分の１に相当する時間が経過した時点）にて取得した電流（励磁電流）をＩｍ１（ｎ－１）とする。 FIG. 10 is an explanatory view showing a fourth example of the method of estimating the magnetic saturation of the transformer 30 by the power supply device 100 of the present embodiment. When the current acquisition unit 51 is in the OFF state of the FET 11 in one switching cycle and a predetermined time has elapsed from the OFF time of the FET 12 (equivalent to one fourth of the resonance cycle Td from the start of the period D4 (n) The current (excitation current) acquired at the time when the time for the lapse of time has elapsed is defined as Im1 (n). Further, when the current acquisition unit 51 is in the OFF state of the FET 11 in the switching cycle earlier than the one switching cycle, and a predetermined time has elapsed from the OFF time of the FET 12 (resonance from the start of the period D4 (n) The current (excitation current) acquired at the time when a time corresponding to one fourth of the cycle Td has elapsed is assumed to be Im1 (n-1).
　推定部５２は、電流Ｉｍ１（ｎ）が第３閾値Ｉｔｈ２以下であって、{Ｉｍ１（ｎ）／Ｉｍ１（ｎ－１）}が第４閾値Ｔｈ２より大きい場合、トランス３０が磁気飽和に至ると推定する。 If the current Im1 (n) is equal to or less than the third threshold Ith2 and {Im1 (n) / Im1 (n-1)} is larger than the fourth threshold Th2, the estimation unit 52 determines that the transformer 30 has reached magnetic saturation. presume.
　制御部５０は、{Ｉｍ１（ｎ）／Ｉｍ１（ｎ－１）}が第４閾値Ｔｈ２より大きい場合、ＦＥＴ１２のオン期間が短くなるようにオン／オフ動作を制御する。 When {Im1 (n) / Im1 (n-1)} is larger than the fourth threshold Th2, the control unit 50 controls the on / off operation so that the on period of the FET 12 becomes short.
　トランス３０の一次巻線３１の電流（すなわち、共振電流）が、スイッチング周期の経過に伴って増加し磁気飽和に至る可能性があるものの、ＦＥＴ１２のデューティ比（オン期間）を調整すれば、磁気飽和状態に陥ることを回避できる場合には、スイッチング動作を停止せずに、ＦＥＴ１２のオン期間が短くなるようにオン／オフ動作を制御する。これにより、電源装置１００を停止させることなく、トランス３０の磁気飽和を未然に防止することができる。 Although the current (that is, the resonance current) of the primary winding 31 of the transformer 30 may increase with the passage of the switching period and lead to magnetic saturation, if the duty ratio (on period) of the FET 12 is adjusted, If it is possible to avoid saturation, the on / off operation is controlled such that the on period of the FET 12 becomes short without stopping the switching operation. Thereby, the magnetic saturation of the transformer 30 can be prevented in advance without stopping the power supply device 100.
　図１１は本実施の形態の電源装置１００の制御方法の処理手順の第１例を示すフローチャートである。制御部５０は、所定のデューティ比に基づいてＦＥＴ１１、ＦＥＴ１２のスイッチングを行う（Ｓ１１）。制御部５０は、ＦＥＴ１２がオフからオンになったか否かを判定し（Ｓ１２）、ＦＥＴ１２がオンになっていない場合（Ｓ１２でＮＯ）、ステップＳ１２の処理を続ける。なお、制御部５０は、ＦＥＴ１１、１２をオンさせるためのゲート電圧の出力を制御するので、ＦＥＴ１１及びＦＥＴ１２のオン時点、オフ時点が分かる。 FIG. 11 is a flow chart showing a first example of the processing procedure of the control method of the power supply device 100 of the present embodiment. The control unit 50 performs switching of the FET 11 and the FET 12 based on a predetermined duty ratio (S11). The control unit 50 determines whether or not the FET 12 is turned on from off (S12), and when the FET 12 is not turned on (NO in S12), the process of step S12 is continued. Since the control unit 50 controls the output of the gate voltage for turning on the FETs 11 and 12, the ON point and the OFF point of the FET 11 and the FET 12 can be known.
　ＦＥＴ１２がオンになった場合（Ｓ１２でＹＥＳ）、制御部５０は、トランス電流（励磁電流に相当）を取得し（Ｓ１３）、取得したトランス電流が電流閾値（第１閾値）より大きいか否かを判定する（Ｓ１４）。トランス電流が電流閾値より大きい場合（Ｓ１４でＹＥＳ）、制御部５０は、ＦＥＴ１１、ＦＥＴ１２のスイッチング動作を停止し（Ｓ１５）、処理を終了する。 When the FET 12 is turned on (YES in S12), the control unit 50 acquires a transformer current (corresponding to the excitation current) (S13), and whether or not the acquired transformer current is larger than the current threshold (first threshold) Is determined (S14). If the transformer current is larger than the current threshold (YES in S14), the control unit 50 stops the switching operation of the FET 11 and the FET 12 (S15), and ends the processing.
　トランス電流が電流閾値より大きくない場合（Ｓ１４でＮＯ）、制御部５０は、今回取得したトランス電流と１周期前にＦＥＴ１２がオフからオンになったときに取得したトランス電流との比が閾値（第２閾値）より大きいか否かを判定する（Ｓ１６）。トランス電流の比が閾値より大きい場合（Ｓ１６でＹＥＳ）、制御部５０は、ＦＥＴ１１のオン期間を短くし（Ｓ１７）、後述のステップＳ１９の処理を行う。 When the transformer current is not larger than the current threshold (NO in S14), the control unit 50 sets the ratio of the ratio of the transformer current acquired this time to the transformer current acquired when the FET 12 is turned on from one period ago earlier It is determined whether it is larger than the second threshold) (S16). If the ratio of the transformer current is larger than the threshold (YES in S16), the control unit 50 shortens the on period of the FET 11 (S17), and performs the process of step S19 described later.
　トランス電流の比が閾値より大きくない場合（Ｓ１６でＮＯ）、制御部５０は、今回取得したトランス電流を記憶部５３に記録し（Ｓ１８）、処理を終了するか否かを判定する（Ｓ１９）。処理を終了しない場合（Ｓ１９でＮＯ）、制御部１０は、ステップＳ１１以降の処理を続ける。処理を終了する場合（Ｓ１９でＹＥＳ）、制御部１０は、処理を終了する。 If the ratio of the transformer current is not larger than the threshold (NO in S16), the control unit 50 records the transformer current acquired this time in the storage unit 53 (S18), and determines whether to end the process (S19) . When the process is not ended (NO in S19), the control unit 10 continues the process after step S11. When the process ends (YES in S19), the control unit 10 ends the process.
　図１２は本実施の形態の電源装置１００の制御方法の処理手順の第２例を示すフローチャートである。制御部５０は、所定のデューティ比に基づいてＦＥＴ１１、ＦＥＴ１２のスイッチングを行う（Ｓ３１）。制御部５０は、ＦＥＴ１２のオフ時点から所定時間が経過したか否かを判定し（Ｓ３２）、所定時間が経過していない場合（Ｓ３２でＮＯ）、ステップＳ３２の処理を続ける。 FIG. 12 is a flowchart illustrating a second example of the processing procedure of the control method of the power supply device 100 according to the present embodiment. The control unit 50 performs switching of the FET 11 and the FET 12 based on a predetermined duty ratio (S31). The control unit 50 determines whether or not a predetermined time has elapsed from the time when the FET 12 is off (S32), and continues the process of step S32 when the predetermined time has not elapsed (NO in S32).
　所定時間が経過した場合（Ｓ３２でＹＥＳ）、制御部５０は、トランス電流（共振電流に相当）を取得し（Ｓ３３）、取得したトランス電流が電流閾値（第３閾値）より大きいか否かを判定する（Ｓ３４）。トランス電流が電流閾値より大きい場合（Ｓ３４でＹＥＳ）、制御部５０は、ＦＥＴ１１、ＦＥＴ１２のスイッチング動作を停止し（Ｓ３５）、処理を終了する。 If the predetermined time has elapsed (YES in S32), the control unit 50 acquires a transformer current (corresponding to a resonant current) (S33), and determines whether the acquired transformer current is larger than the current threshold (third threshold). It determines (S34). If the transformer current is larger than the current threshold (YES in S34), the control unit 50 stops the switching operation of the FET 11 and the FET 12 (S35), and ends the processing.
　トランス電流が電流閾値より大きくない場合（Ｓ３４でＮＯ）、制御部５０は、今回取得したトランス電流と１周期前にＦＥＴ１２のオフ時点から所定時間経過時に取得したトランス電流との比が閾値（第４閾値）より大きいか否かを判定する（Ｓ３６）。トランス電流の比が閾値より大きい場合（Ｓ３６でＹＥＳ）、制御部５０は、ＦＥＴ１２のオン期間を短くし（Ｓ３７）、後述のステップＳ３９の処理を行う。 When the transformer current is not larger than the current threshold (NO in S34), the control unit 50 sets the ratio of the ratio of the transformer current acquired this time to the transformer current acquired when a predetermined time has elapsed from the OFF point of one period ago. It is determined whether the threshold is greater than 4) (S36). If the ratio of the transformer current is larger than the threshold (YES in S36), the control unit 50 shortens the on period of the FET 12 (S37), and performs the process of step S39 described later.
　トランス電流の比が閾値より大きくない場合（Ｓ３６でＮＯ）、制御部５０は、今回取得したトランス電流を記憶部５３に記録し（Ｓ３８）、処理を終了するか否かを判定する（Ｓ３９）。処理を終了しない場合（Ｓ３９でＮＯ）、制御部１０は、ステップＳ３１以降の処理を続ける。処理を終了する場合（Ｓ３９でＹＥＳ）、制御部１０は、処理を終了する。 If the ratio of the transformer current is not larger than the threshold (NO in S36), the control unit 50 records the transformer current acquired this time in the storage unit 53 (S38), and determines whether to end the process (S39) . When the process is not ended (NO in S39), the control unit 10 continues the process after step S31. When the process ends (YES in S39), the control unit 10 ends the process.
　本実施の形態の電源装置１００の制御方法は、制御部５０を、例えば、ＣＰＵ（プロセッサ）、ＲＡＭ（メモリ）などで構成し、図１１及び図１２に示すような、各処理の手順を定めたコンピュータプログラムをＲＡＭ（メモリ）にロードし、コンピュータプログラムをＣＰＵ（プロセッサ）で実行することにより、コンピュータ上で電源装置１００の制御方法を実現することができる。 In the control method of power supply apparatus 100 according to the present embodiment, control unit 50 includes, for example, a CPU (processor), a RAM (memory), and the like, and determines the procedure of each process as shown in FIGS. By loading the computer program into the RAM (memory) and executing the computer program by the CPU (processor), the control method of the power supply apparatus 100 can be realized on the computer.
　スイッチング素子はＭＯＳＦＥＴに限定されるものではなく、ＩＧＢＴ（Insulated Gate Bipolar Transistor）などのデバイスであってもよい。本実施の形態のように、スイッチング素子が、ＭＯＳＦＥＴの場合には、ドレイン・ソース間には等価的に内蔵されたボディダイオードが存在する。また、スイッチング素子として、バイポーラトランジスタを用いる場合には、トランジスタのコレクタ・エミッタ間にダイオードを逆並列に接続すればよい。 The switching element is not limited to the MOSFET, and may be a device such as an IGBT (Insulated Gate Bipolar Transistor). As in the present embodiment, when the switching element is a MOSFET, there is a body diode built in equivalently between the drain and the source. When a bipolar transistor is used as a switching element, a diode may be connected in anti-parallel between the collector and the emitter of the transistor.
　本実施の形態では、電源装置として、図１に示したようなＤＣ／ＤＣコンバータの構成を例に挙げて説明したが、ＤＣ／ＤＣコンバータの構成は図１に例示した構成に限定されるものではなく、トランスの一次巻線に直列にスイッチング素子が接続され、トランスの磁気リセットが行われるような構成であればよい。 In the present embodiment, the configuration of the DC / DC converter as shown in FIG. 1 is described as an example of the power supply device, but the configuration of the DC / DC converter is limited to the configuration illustrated in FIG. Instead, the switching element may be connected in series to the primary winding of the transformer, and the magnetic reset of the transformer may be performed.
　図１３は本実施の形態の電源装置１２０の回路構成の他の例を示す説明図である。前述の図１に示す電源装置１００は、アクティブクランプ回路を備える構成であったが、本実施の形態は、アクティブクランプ回路を具備しない電源装置にも適用することができる。図１に示した電源装置１００との相違点は、電圧センサ７２、７３、及び電圧取得部５４を備える点である。また、キャパシタ２１に代えてキャパシタＣ１１（浮遊容量でもよい）が存在し、キャパシタ２２に代えてキャパシタＣ１３を備え、さらに、キャパシタＣ１２（浮遊容量でもよい）が存在する点である。ＦＥＴ１２とキャパシタＣ１３とは、アクティブクランプ回路を構成しない。 FIG. 13 is an explanatory view showing another example of the circuit configuration of the power supply device 120 according to the present embodiment. The power supply device 100 shown in FIG. 1 described above is configured to include the active clamp circuit, but the present embodiment can also be applied to a power supply device that does not include the active clamp circuit. The difference from the power supply device 100 shown in FIG. 1 is that the voltage sensors 72 and 73 and the voltage acquisition unit 54 are provided. Also, instead of the capacitor 21, a capacitor C11 (may be a floating capacitance) exists, and instead of the capacitor 22, a capacitor C13 is provided, and further, a capacitor C12 (may be a floating capacitance). The FET 12 and the capacitor C13 do not constitute an active clamp circuit.
　電圧取得部５４は、電圧センサ７２で検出した入力電圧（直流）、及び電圧センサ７３で検出した出力電圧（直流）を取得する。制御部５０は、電圧取得部５４で取得した電圧に基づいて、出力電圧が目標値になるようにＦＥＴ１１、ＦＥＴ１２のスイッチングを制御する。 The voltage acquisition unit 54 acquires an input voltage (DC) detected by the voltage sensor 72 and an output voltage (DC) detected by the voltage sensor 73. The control unit 50 controls switching of the FET 11 and the FET 12 based on the voltage acquired by the voltage acquisition unit 54 so that the output voltage becomes a target value.
　図１３に示す電源装置１２０の動作は、図１に示した電源装置１００の動作と同様であるので、以下、簡単に説明する。 The operation of the power supply device 120 shown in FIG. 13 is the same as the operation of the power supply device 100 shown in FIG.
　電流取得部５１は、トランス３０の一次巻線３１に流れる電流を取得する。 The current acquisition unit 51 acquires the current flowing through the primary winding 31 of the transformer 30.
　推定部５２は、ＦＥＴ１２のオン時点にて取得した電流に基づいて、トランス３０が磁気飽和に至るか否かを推定する。また、推定部５２は、ＦＥＴ１２のオフ時点から所定時間が経過した時点にて、取得した電流に基づいて、トランス３０が磁気飽和に至るか否かを推定する。なお、磁気飽和に至ると推定するとは、まだ磁気飽和に至っていない状態での推定である。 The estimation unit 52 estimates whether or not the transformer 30 reaches magnetic saturation based on the current acquired at the on time of the FET 12. Further, the estimation unit 52 estimates whether or not the transformer 30 reaches magnetic saturation based on the acquired current when a predetermined time has elapsed from the time when the FET 12 is turned off. The assumption that magnetic saturation is reached is an estimation in a state where magnetic saturation has not yet been reached.
　ＦＥＴ１２がオフ状態（期間Ｄ１と称する）では、トランス３０の一次巻線３１には入力側の電圧が印加され、トランス３０の一次巻線３１には、負荷電流及び励磁電流の合計が流れる。 When the FET 12 is in the off state (referred to as a period D1), a voltage on the input side is applied to the primary winding 31 of the transformer 30, and a total of load current and excitation current flows through the primary winding 31 of the transformer 30.
　ＦＥＴ１１がオフとなり、ＦＥＴ１１及びＦＥＴ１２の両者がオフ状態（期間Ｄ２と称する）では、励磁電流は一定値に維持されるが負荷電流は減少する。 When the FET 11 is turned off and both the FET 11 and the FET 12 are turned off (referred to as a period D2), the excitation current is maintained at a constant value but the load current is decreased.
　ＦＥＴ１２のオン時点（期間Ｄ２の終了時点、期間Ｄ３の開始時点）では、トランス３０の一次巻線３１に流れる負荷電流は０となり励磁電流だけになる。そこで、ＦＥＴ１２のオン時点にて取得した電流は励磁電流だけとなり、負荷電流の影響を除外してトランス３０の磁気飽和の可能性を正確に推定することができる。 At the point in time when the FET 12 is on (when the period D2 ends, the period D3 starts), the load current flowing through the primary winding 31 of the transformer 30 is zero and only the excitation current. Therefore, the current acquired at the ON time of the FET 12 is only the excitation current, and the influence of the load current can be excluded to accurately estimate the possibility of the magnetic saturation of the transformer 30.
　ＦＥＴ１２がオン状態（期間Ｄ３と称する）では、トランス３０の励磁電流は減少する。 When the FET 12 is in the on state (referred to as a period D3), the excitation current of the transformer 30 decreases.
　ＦＥＴ１２がオフとなり、ＦＥＴ１１及びＦＥＴ１２の両者がオフ状態（期間Ｄ４と称する）では、トランス３０の漏れインダクタンス及びＦＥＴ１１の両端に存在するキャパシタＣ１１（浮遊容量も含む）に依拠する共振が発生し、トランス３０の一次巻線３１には共振電流が流れる。磁気飽和に至る予兆として磁束バランスが崩れると共振電流の振幅が増加するので、ＦＥＴ１２のオフ時点から所定時間が経過した時点（例えば、共振中の所要の時点）にて取得した電流（すなわち共振電流）に基づいて、トランス３０の磁気飽和の可能性を正確に推定することができる。 When the FET 12 is turned off and both the FET 11 and the FET 12 are turned off (referred to as a period D4), resonance based on the leakage inductance of the transformer 30 and the capacitor C11 (including stray capacitance) present at both ends of the FET 11 occurs. A resonant current flows through the primary winding 31 of 30. Since the amplitude of the resonant current increases as the magnetic flux balance breaks down as a sign of reaching magnetic saturation, the current obtained at a time when a predetermined time has elapsed since the time when the FET 12 was turned off (for example, the required time during resonance) Can accurately estimate the possibility of magnetic saturation of the transformer 30.
　また、共振電流は、電流０を間にして正側と負側の両方に共振するので、共振電流の正側の振幅を検出すれば、共振電流の負側の振幅を推定することができる。従って、正極性のみ検知可能な電流センサを用いても、トランス３０の負側の励磁電流による磁気飽和を推定することができる。 In addition, since the resonance current resonates on both the positive side and the negative side with current 0 in between, if the amplitude on the positive side of the resonance current is detected, the amplitude on the negative side of the resonance current can be estimated. Therefore, magnetic saturation due to the excitation current on the negative side of the transformer 30 can be estimated even if a current sensor capable of detecting only the positive polarity is used.
　制御部５０は、推定部５２の推定結果に基づいてＦＥＴ１２のオン／オフ動作を制御する。磁気飽和となる前にＦＥＴ１２のオン／オフ動作を制御することができる。これにより、トランス３０の磁気飽和を未然に防止することができる。 The control unit 50 controls the on / off operation of the FET 12 based on the estimation result of the estimation unit 52. The on / off operation of the FET 12 can be controlled before the magnetic saturation occurs. Thereby, magnetic saturation of the transformer 30 can be prevented in advance.
　以上に開示された実施の形態及び実施例は、全ての点で例示であって制限的なものではないと考慮されるべきである。本発明の範囲は、以上の実施の形態及び実施例ではなく、請求の範囲によって示され、請求の範囲と均等の意味及び範囲内での全ての修正や変形を含むものと意図される。 The embodiments and examples disclosed above should be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments and examples but by the scope of the claims, and is intended to include all the modifications and variations within the meaning and scope equivalent to the scope of the claims.
　１１、１２　ＦＥＴ
　２１、２２、２３　キャパシタ
　３０　トランス
　３１　一次巻線
　３２　二次巻線
　４１、４２　ダイオード
　５０　制御部
　５１　電流取得部
　５２　推定部
　５３　記憶部
　５４　電圧取得部
　６１　インダクタ
　７１　カレンントトランス
　７２、７３　電圧センサ
　１００、１２０　電源装置
　Ｃ１１、Ｃ１２、Ｃ１３　キャパシタ
  11, 12 FET
21, 22, 23 capacitor 30 transformer 31 primary winding 32 secondary winding 41, 42 diode 50 control unit 51 current acquisition unit 52 estimation unit 53 storage unit 54 voltage acquisition unit 61 inductor 71 current transformer 72, 73 voltage sensor 100 , 120 power supply C11, C12, C13 capacitors

Claims (9)

  1. 　トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、該第１のスイッチング素子に並列に接続された第１のキャパシタと、前記一次巻線に並列に接続された第２のスイッチング素子及び第２のキャパシタの直列回路と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置であって、
    　前記トランスの電流を取得する電流取得部と、
    　前記第１のスイッチング素子がオフ状態であって、前記第２のスイッチング素子のオン時点にて又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて前記電流取得部で取得した電流に基づいて、前記トランスが磁気飽和に至るか否かを推定する推定部と
    　を備え、
    　前記制御部は、
    　前記推定部の推定結果に基づいて前記第１のスイッチング素子又は第２のスイッチング素子のオン／オフ動作を制御する電源装置。     A transformer, a first switching element connected in series to the primary winding of the transformer, a first capacitor connected in parallel to the first switching element, and a parallel connected to the primary winding A power supply device, comprising: a series circuit of a second switching element and a second capacitor; and a control unit configured to turn on / off the first switching element and the second switching element in a predetermined switching cycle,
    A current acquisition unit that acquires the current of the transformer;
    The current is acquired by the current acquisition unit when the first switching element is in the off state and a predetermined time has elapsed from the turning on of the second switching element or from the turning off of the second switching element. An estimation unit for estimating whether or not the transformer reaches magnetic saturation based on a current;
    The control unit
    The power supply device which controls on / off operation of said 1st switching element or 2nd switching element based on the presumed result of said estimation part.
  2. 　前記推定部は、
    　前記第２のスイッチング素子のオン時点にて前記電流取得部で取得した電流と、第１閾値とに基づいて、前記トランスが磁気飽和に至ると推定し、
    　前記制御部は、
    　前記第１のスイッチング素子及び第２のスイッチング素子のオン／オフ動作を停止する請求項１に記載の電源装置。     The estimation unit
    Based on the current acquired by the current acquisition unit at the on time of the second switching element and the first threshold value, it is estimated that the transformer reaches magnetic saturation,
    The control unit
    The power supply device according to claim 1, wherein the on / off operation of the first switching element and the second switching element is stopped.
  3. 　前記推定部は、
    　一のスイッチング周期で前記第２のスイッチング素子のオン時点にて前記電流取得部で取得した第１電流と、第１閾値とに基づくとともに、
    　前記第１電流と、
    　前記一のスイッチング周期よりも前のスイッチング周期で前記第２のスイッチング素子のオン時点にて前記電流取得部で取得した第２電流との比と、第２閾値とに基づいて、前記トランスが磁気飽和に至ると推定し、
    　前記制御部は、
    　前記第１のスイッチング素子のオン期間が短くなるようにオン／オフ動作を制御する請求項１又は請求項２に記載の電源装置。     The estimation unit
    Based on the first current acquired by the current acquisition unit at the on time of the second switching element in one switching cycle, and the first threshold,
    The first current;
    The transformer is magnetic based on a ratio to the second current acquired by the current acquisition unit at the on time point of the second switching element in a switching cycle earlier than the one switching cycle, and on a second threshold. Estimated to reach saturation,
    The control unit
    The power supply device according to claim 1 or 2, wherein the on / off operation is controlled such that the on period of the first switching element becomes short.
  4. 　前記推定部は、
    　前記第２のスイッチング素子のオフ時点から前記所定時間が経過した時点にて前記電流取得部で取得した電流と、第３閾値とに基づいて、前記トランスが磁気飽和に至ると推定し、
    　前記制御部は、
    　前記第１のスイッチング素子及び第２のスイッチング素子のオン／オフ動作を停止する請求項１に記載の電源装置。     The estimation unit
    It is estimated that the transformer reaches magnetic saturation based on the current acquired by the current acquiring unit at the time when the predetermined time has elapsed from the time when the second switching element is turned off and the third threshold,
    The control unit
    The power supply device according to claim 1, wherein the on / off operation of the first switching element and the second switching element is stopped.
  5. 　前記推定部は、
    　一のスイッチング周期で前記第２のスイッチング素子のオフ時点から前記所定時間が経過した時点にて前記電流取得部で取得した第１電流と、第３閾値とに基づくとともに、
    　前記第１電流と、
    　前記一のスイッチング周期よりも前のスイッチング周期で前記第２のスイッチング素子のオフ時点から前記所定時間が経過した時点にて前記電流取得部で取得した第２電流との比と、第４閾値とに基づいて、前記トランスが磁気飽和に至ると推定し、
    　前記制御部は、
    　前記第２のスイッチング素子のオン期間が短くなるようにオン／オフ動作を制御する請求項１又は請求項４に記載の電源装置。     The estimation unit
    Based on the first current acquired by the current acquisition unit and the third threshold when the predetermined time has elapsed from the time when the second switching element is turned off in one switching cycle, and
    The first current;
    A ratio of the second current acquired by the current acquisition unit when the predetermined time has elapsed from the time when the second switching element is turned off in a switching cycle earlier than the one switching cycle, and a fourth threshold value; Estimate that the transformer leads to magnetic saturation,
    The control unit
    The power supply device according to claim 1, wherein the on / off operation is controlled so that the on period of the second switching element becomes short.
  6. 　前記所定時間は、前記トランスの漏れインダクタンス及び前記第１のキャパシタのキャパシタンスに依拠する共振周期の１／４の時間及び該時間の近傍時間を含む請求項１、請求項４又は請求項５のいずれか一項に記載の電源装置。 The predetermined time includes a time of 1⁄4 of a resonance period depending on a leakage inductance of the transformer and a capacitance of the first capacitor, and a time near the time. The power supply device according to any one of the preceding claims.
  7. 　トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、前記一次巻線に並列に接続された第２のスイッチング素子と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置であって、
    　前記トランスの電流を取得する電流取得部と、
    　前記第２のスイッチング素子のオン時点又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて前記電流取得部で取得した電流に基づいて、前記トランスが磁気飽和に至るか否かを推定する推定部と
    　を備え、
    　前記制御部は、
    　前記推定部の推定結果に基づいて前記第２のスイッチング素子のオン／オフ動作を制御する電源装置。     A transformer, a first switching element connected in series to the primary winding of the transformer, a second switching element connected in parallel to the primary winding, the first switching element and the second switching And a control unit configured to turn on / off the element in a predetermined switching cycle, the power supply apparatus comprising:
    A current acquisition unit that acquires the current of the transformer;
    Whether or not the transformer reaches magnetic saturation based on the current acquired by the current acquisition unit when a predetermined time has elapsed from the time when the second switching element is turned on or when the second switching element is turned off And an estimation unit for estimating
    The control unit
    A power supply device controlling on / off operation of the second switching element based on the estimation result of the estimation unit.
  8. 　トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、該第１のスイッチング素子に並列に接続された第１のキャパシタと、前記一次巻線に並列に接続された第２のスイッチング素子及び第２のキャパシタの直列回路と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置の制御方法であって、
    　前記トランスの電流を取得し、
    　前記第１のスイッチング素子がオフ状態であって、前記第２のスイッチング素子のオン時点にて又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて、取得された電流に基づいて、前記トランスが磁気飽和に至るか否かを推定し、
    　前記制御部は、
    　推定結果に基づいて前記第１のスイッチング素子又は第２のスイッチング素子のオン／オフ動作を制御する電源装置の制御方法。     A transformer, a first switching element connected in series to the primary winding of the transformer, a first capacitor connected in parallel to the first switching element, and a parallel connected to the primary winding A control method of a power supply device, comprising: a series circuit of a second switching element and a second capacitor; and a control unit for turning on / off the first switching element and the second switching element in a predetermined switching cycle. ,
    Get the current of the transformer,
    Based on the current obtained when the first switching element is in the off state and a predetermined time has elapsed from the time when the second switching element is turned on or when the second switching element is turned off Estimate whether the transformer reaches magnetic saturation,
    The control unit
    A control method of a power supply device, which controls on / off operation of the first switching element or the second switching element based on an estimation result.
  9. 　トランスと、該トランスの一次巻線に直列に接続された第１のスイッチング素子と、前記一次巻線に並列に接続された第２のスイッチング素子と、前記第１のスイッチング素子及び第２のスイッチング素子を所定のスイッチング周期でオン／オフ動作させる制御部とを備える電源装置の制御方法であって、
    　前記トランスの電流を取得し、
    　前記第２のスイッチング素子のオン時点又は前記第２のスイッチング素子のオフ時点から所定時間が経過した時点にて、取得された電流に基づいて、前記トランスが磁気飽和に至るか否かを推定し、
    　前記制御部は、
    　推定結果に基づいて前記第２のスイッチング素子のオン／オフ動作を制御する電源装置の制御方法。
          A transformer, a first switching element connected in series to the primary winding of the transformer, a second switching element connected in parallel to the primary winding, the first switching element and the second switching And a control unit for turning on / off the element in a predetermined switching cycle.
    Get the current of the transformer,
    Whether or not the transformer reaches magnetic saturation is estimated based on the acquired current when a predetermined time has elapsed from the on time of the second switching element or the off time of the second switching element ,
    The control unit
    The control method of the power supply device which controls the on / off operation of the said 2nd switching element based on an estimation result.
PCT/JP2018/047132 2017-12-26 2018-12-21 Power supply device and power supply device control method WO2019131469A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5331533A (en) * 1991-03-13 1994-07-19 Astec International, Ltd. Zero voltage switching power converters
JP2008199878A (en) * 2007-01-19 2008-08-28 Toyota Industries Corp Method of control of dc-dc converter, and dc-dc converter
JP2009290932A (en) * 2008-05-27 2009-12-10 Toyota Industries Corp Switching power supply unit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5331533A (en) * 1991-03-13 1994-07-19 Astec International, Ltd. Zero voltage switching power converters
JP2008199878A (en) * 2007-01-19 2008-08-28 Toyota Industries Corp Method of control of dc-dc converter, and dc-dc converter
JP2009290932A (en) * 2008-05-27 2009-12-10 Toyota Industries Corp Switching power supply unit

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