JP2010041855A - Dc-dc converter, switching power supply, and uninterruptible power supply apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a ripple current of an output capacitor even if there exists variations or fluctuation in characteristics of a circuit component. <P>SOLUTION: Converters Conv11 and Conv21 are connected in parallel to an output capacitor Co. A phase difference setting part 31 sets a phase difference θ for switching control by phase shift control parts 11 and 21. The phase shift control parts 11 and 21 control the switching operations of switching elements Q11-Q14, Q21-Q24 so that DC is applied to resonance circuits 12a and 22a while its polarity is inverted alternately. They also control the switching operations of the switching elements Q11-Q14, Q21-Q24 so that DC applied to the resonance circuits 12a and 22a is bypassed during a period when the polarity of DC applied to the resonance circuits 12a and 22a is inverted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a DCDC converter, a switching power supply, and an uninterruptible power supply, and is particularly suitable for application to a method for reducing a ripple current flowing in an output capacitor of a DCDC converter using a current resonance circuit.

  In the DCDC converter, on / off control of the switching element is performed in order to step up or step down the direct current, and the current output to the output capacitor becomes a pulsating flow, so that a ripple is generated. For this reason, in a conventional DCDC converter, an output capacitor having a large capacity has been selected in order to ensure a current allowable value of the output capacitor for such a rippled current.

  Here, for example, in Patent Document 1, in order to suppress the ripple current of the smoothing capacitor, two pairs of transformers are connected in parallel to the switching output of the primary side current resonance type converter. A method is disclosed in which a double-wave rectifier circuit is formed on each secondary side, and switching circuits of switching elements are connected in parallel so that the respective primary windings of the transformer have opposite polarities.

JP 2004-254440 A

  However, in the method disclosed in Patent Document 1, on the assumption that an unbalance of the rectified current level corresponding to each half cycle of both-wave rectification occurs due to the winding structure of the transformer winding, When a rectified current biased to a high level is output, the other transformer is configured to always output a rectified current biased to a low level, which is caused by the winding position of the winding of the transformer. There was a problem that only the ripple current component due to the unbalanced rectified current could be suppressed.

  Accordingly, an object of the present invention is to provide a DCDC converter, a switching power supply, and an uninterruptible power supply apparatus that can reduce the ripple current of an output capacitor even when there are variations and fluctuations in characteristics of circuit components. .

  In order to solve the above-described problem, according to the DCDC converter according to claim 1, the first orthogonal transform unit that converts direct current into a rectangular wave based on the switching operation of the first switching element group, and the first The first resonance circuit that resonates the rectangular wave output from the orthogonal transformation unit, the first rectification unit that rectifies the resonance current resonated in the first resonance circuit, and the direct current alternate in polarity A period during which the polarity of the direct current applied to the first resonance circuit is reversed while controlling the switching operation of the first switching element group so as to be applied to the first resonance circuit while being inverted. A first switching control unit for controlling a switching operation of the first switching element group so as to bypass application of the direct current to the first resonance circuit, and a second switching unit. A second orthogonal transform unit that converts direct current into a rectangular wave based on a switching operation of the element group; a second resonance circuit that resonates the rectangular wave output from the second orthogonal transform unit; and the second A second rectifier that rectifies the resonance current resonated in the resonance circuit; and switching of the second switching element group so that the direct current is applied to the second resonance circuit while the polarity is alternately inverted. Controlling the operation and bypassing application of the direct current to the second resonant circuit during a period during which the polarity of the direct current applied to the second resonant circuit is reversed. A second switching control unit for controlling a switching operation of the switching element group, switching control by the first switching control unit, and switching control by the second switching control unit; Characterized in that it comprises a phase difference setting unit for setting a phase difference, and an output capacitor and an output from the output from the first rectifying portion and the second rectifying unit is input in parallel between.

  According to the DCDC converter of the second aspect, the first orthogonal transform unit that converts direct current into a rectangular wave based on the switching operation of the first switching element group, and the first orthogonal transform unit are output. A first resonance circuit that resonates the rectangular wave, a first transformer that transforms a resonance current resonated by the first resonance circuit, and a rectification of the resonance current transformed by the first transformer The first rectifier unit controls the switching operation of the first switching element group so that the direct current is applied to the first resonant circuit while alternately inverting the polarity, and the first resonant circuit The switching operation of the first switching element group is controlled so as to bypass the application of the direct current to the first resonance circuit during a period during which the polarity of the direct current applied to the inverter is reversed. 1 switching control unit, a second orthogonal transform unit that converts direct current into a rectangular wave based on a switching operation of the second switching element group, and a rectangular wave output from the second orthogonal transform unit A second resonance circuit; a second transformer that transforms the resonance current resonated by the second resonance circuit; and a second rectifier that rectifies the resonance current transformed by the second transformer; , Controlling the switching operation of the second switching element group so that the direct current is applied to the second resonant circuit while the polarity is alternately inverted, and the direct current applied to the second resonant circuit is A second switching control for controlling a switching operation of the second switching element group so as to bypass the application of the direct current to the second resonance circuit during a period during which the polarity is inverted. A phase difference setting unit that sets a phase difference between the switching control by the first switching control unit and the switching control by the second switching control unit, the output from the first rectifying unit, and the And an output capacitor to which an output from the second rectifier is input in parallel.

  According to the DCDC converter of claim 3, the first switching element group includes a first switching element connected between the DC positive electrode side and the high potential side of the first resonance circuit. A second switching element connected between the negative electrode side of the direct current and the high potential side of the first resonance circuit, and a positive electrode side of the direct current and the low potential side of the first resonance circuit A third switching element connected in between, and a fourth switching element connected between the negative electrode side of the direct current and the low potential side of the first resonance circuit, and the second switching element A group comprising: a fifth switching element connected between the direct current positive electrode side and the high potential side of the second resonance circuit; the direct current negative electrode side; and the high potential side of the second resonance circuit; A sixth switching element connected between the DC and the DC A seventh switching element connected between the positive electrode side and the low potential side of the second resonance circuit; and a seventh switching element connected between the negative electrode side of the DC and the low potential side of the second resonance circuit. An eighth switching element, and the first switching control unit turns on and off the first switching element and the second switching element so that the phase difference is 180 degrees and the duty ratio is 50%. And the phase difference is 180 degrees and the duty ratio is 50%, and the first switching element and the second switching element are out of phase within a range larger than 0 degree and smaller than 180 degrees. The third switching element and the fourth switching element are controlled to be turned on / off, and the second switching control unit has a phase difference of 180 degrees and a duty ratio of 50%. The fifth switching element and the sixth switching element are turned on / off so that the phase difference is 180 degrees and the duty ratio is 50%, and the fifth switching element and the sixth switching element are The seventh switching element and the eighth switching element are on / off controlled so that the phase is shifted within a range larger than 0 degree and smaller than 180 degrees with respect to the switching element, and the phase difference setting unit The phase difference between the switching control by the first switching control unit and the switching control by the second switching control unit is set to 90 degrees.

  The DCDC converter according to claim 4, wherein the first switching element group is a first switching element connected between the positive electrode side of the direct current and the high potential side of the first resonance circuit. A second switching element connected between the negative electrode side of the direct current and the high potential side of the first resonance circuit, and a positive electrode side of the direct current and the low potential side of the first resonance circuit A third switching element connected in between, and a fourth switching element connected between the negative electrode side of the direct current and the low potential side of the first resonance circuit, and the second switching element A group comprising: a fifth switching element connected between the direct current positive electrode side and the high potential side of the second resonance circuit; the direct current negative electrode side; and the high potential side of the second resonance circuit; A sixth switching element connected between the DC and the DC A seventh switching element connected between the positive electrode side and the low potential side of the second resonance circuit; and a seventh switching element connected between the negative electrode side of the DC and the low potential side of the second resonance circuit. An eighth switching element, and the first switching control unit turns on the second switching element and the fourth switching element so as to be alternately turned on at predetermined time intervals within one cycle. On / off control, and on / off control of the first switching element and the third switching element so as to invert the second switching element and the fourth switching element, respectively. The on / off control of the sixth switching element and the eighth switching element so that the switching control unit of the first and second switching elements alternately turn on at predetermined time intervals within one period. Further, the fifth switching element and the seventh switching element are controlled to be turned on / off so as to perform the inversion operations of the sixth switching element and the eighth switching element, respectively, and the phase difference setting unit includes: The phase difference between the switching control by the first switching control unit and the switching control by the second switching control unit is set to 90 degrees.

  The DCDC converter according to claim 5, wherein the first switching element group is a first switching element connected between the positive electrode side of the direct current and the high potential side of the first resonance circuit. A second switching element connected between the negative electrode side of the direct current and the high potential side of the first resonance circuit, and a positive electrode side of the direct current and the low potential side of the first resonance circuit A third switching element connected in between, and a fourth switching element connected between the negative electrode side of the direct current and the low potential side of the first resonance circuit, and the second switching element A group comprising: a fifth switching element connected between the direct current positive electrode side and the high potential side of the second resonance circuit; the direct current negative electrode side; and the high potential side of the second resonance circuit; A sixth switching element connected between the DC and the DC A seventh switching element connected between the positive electrode side and the low potential side of the second resonance circuit; and a seventh switching element connected between the negative electrode side of the DC and the low potential side of the second resonance circuit. An eighth switching element, and the first switching control unit turns on the first switching element and the third switching element so as to be alternately turned on at predetermined time intervals within one cycle. The second switching element and the fourth switching element are turned on / off so as to perform the inversion operations of the first switching element and the third switching element, respectively. The on / off control of the fifth switching element and the seventh switching element is performed so that the switching control unit of the second switching element alternately turns on at predetermined time intervals within one cycle. Further, the sixth switching element and the eighth switching element are controlled to be turned on / off so as to perform the inversion operations of the fifth switching element and the seventh switching element, respectively, and the phase difference setting unit includes: The phase difference between the switching control by the first switching control unit and the switching control by the second switching control unit is set to 90 degrees.

  Further, according to the switching power supply of claim 6, the AC / DC conversion circuit for converting AC to DC and the DC output from the AC / DC conversion circuit are stepped up or down and output. It is provided with the DCDC converter of description.

  Further, according to the uninterruptible power supply device according to claim 7, the DCDC converter according to any one of claims 1 to 5, a battery for storing direct current output from the DCDC converter, and direct current to alternating current are converted. And an inverter.

  As described above, according to the present invention, it is possible to supply current from a plurality of converters to an output capacitor while allowing phases of currents supplied from the converters to the output capacitor to be different from each other. At the same time, the peak value of the current supplied from each converter to the output capacitor can be adjusted while keeping the frequency constant. For this reason, even when there are variations or fluctuations in the characteristics of circuit components, the peak value of the current supplied from each converter to the output capacitor can be made uniform, and the ripple current of the output capacitor can be reduced. Therefore, the output capacitor can be reduced in capacity, and the DCDC converter can be reduced in size and price.

Hereinafter, a DCDC converter according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of the DCDC converter according to the first embodiment of the present invention.
In FIG. 1, the DCDC converter is provided with converters Conv11 and Conv21 that perform power conversion based on a switching operation, and the converters Conv11 and Conv21 are connected in parallel to each other. That is, the input capacitor Cin is provided in the previous stage of the converters Conv11 and Conv21, the inputs of the converters Conv11 and Conv21 are connected in parallel to the input capacitor Cin, and the output capacitor Co is provided in the subsequent stage of the converters Conv11 and Conv21. The outputs of the converters Conv11 and Conv21 are connected in parallel to the output capacitor Co. A series circuit of a DC power source Ei and a resistor R1 is connected in parallel to the input capacitor Cin, and a load resistor RL is connected in parallel to the output capacitor Co.

  Here, the converter Conv11 is provided with an orthogonal transform circuit 11a, a resonance circuit 12a, a transformer T1, and a rectifier circuit 13a. And the orthogonal transformation circuit 11a can convert direct current into a rectangular wave based on the switching operation of the switching elements Q11 to Q14. The resonance circuit 12a can resonate the rectangular wave output from the orthogonal transformation circuit 11a. The transformer T1 can transform the resonance current resonated by the resonance circuit 12a. The rectifier circuit 13a can rectify the resonance current transformed by the transformer T1.

  Further, the converter Conv21 is provided with an orthogonal transform circuit 21a, a resonance circuit 22a, a transformer T2, and a rectifier circuit 23a. And the orthogonal transformation circuit 21a can convert direct current into a rectangular wave based on the switching operation of the switching elements Q21 to Q24. The resonance circuit 22a can resonate the rectangular wave output from the orthogonal transformation circuit 21a. The transformer T2 can transform the resonance current resonated by the resonance circuit 22a. The rectifier circuit 23a can rectify the resonance current transformed by the transformer T2.

  The DCDC converter includes phase shift control units 11 and 21 and a phase difference setting unit 31. Here, the phase shift control unit 11 controls the switching operation of the switching elements Q11 to Q14 so that the direct current is applied to the resonance circuit 12a while alternately inverting the polarity, and the direct current applied to the resonance circuit 12a is also controlled. The switching operation of the switching elements Q11 to Q14 can be controlled so as to bypass the application of direct current to the resonance circuit 12a during the period during which the polarity is inverted. In addition, the phase shift control unit 21 controls the switching operation of the switching elements Q21 to Q24 so that the direct current is applied to the resonance circuit 22a while alternately inverting the polarity, and the polarity of the direct current applied to the resonance circuit 22a. The switching operation of the switching elements Q21 to Q24 can be controlled so as to bypass the application of a direct current to the resonance circuit 22a during the period during which is inverted. Further, the phase difference setting unit 31 can set the phase difference θ between the switching control by the phase shift control unit 11 and the switching control by the phase shift control unit 21. The phase difference θ can be set to an arbitrary value within a range larger than 0 degree and smaller than 180 degrees, and particularly preferably set to 90 degrees.

  An input capacitor Cin is connected in parallel before the orthogonal transform circuits 11a and 21a. Resonant circuits 12a and 22a are connected to the subsequent stages of the orthogonal transform circuits 11a and 21a, respectively, and rectifier circuits 13a and 23a are connected to the subsequent stages of the resonant circuits 12a and 22a via the transformers T1 and T2, respectively. ing. An output capacitor Co is connected in parallel to the output side of the rectifier circuits 13a and 23a.

  Specifically, switching elements Q11 to Q14 are provided in the orthogonal transform circuit 11a. Switching elements Q11 and Q12 are connected in series with each other, and switching elements Q13 and Q14 are connected in series with each other. The series circuit of the switching elements Q11 and Q12 is connected in parallel to the input capacitor Cin, and the series circuit of the switching elements Q13 and Q14 is connected in parallel to the input capacitor Cin. Further, diodes Dq11 to Dq14 are respectively connected in parallel to switching elements Q11 to Q14, and capacitors Cq11 to Cq14 are respectively connected in parallel.

  In addition, switching elements Q21 to Q24 are provided in the orthogonal transform circuit 21a. The switching elements Q21 and Q22 are connected in series with each other, and the switching elements Q23 and Q24 are connected in series with each other. The series circuit of the switching elements Q21 and Q22 is connected in parallel to the input capacitor Cin, and the series circuit of the switching elements Q23 and Q24 is connected in parallel to the input capacitor Cin. Further, diodes Dq21 to Dq24 are respectively connected in parallel to switching elements Q21 to Q24, and capacitors Cq21 to Cq24 are respectively connected in parallel.

  As the switching elements Q11 to Q14 and Q21 to Q24, for example, a field effect transistor or an IGBT (insulated gate bipolar transistor) can be used. Capacitors Cq11-Cq14, Cq21-Cq24 may be substituted with drain-source capacitances of field effect transistors, and diodes Dq11-Dq14, Dq21-Dq24 are source-channel junctions of field effect transistors, etc. May be substituted.

  The resonance circuit 12a is provided with a resonance inductor Lr1 and a resonance capacitor Cr1, and is provided with a high potential side terminal Va1 and a low potential side terminal Vb1. The high potential side terminal Va1 is connected to the connection point of the switching elements Q11 and Q12, and the low potential side terminal Vb1 is connected to the connection point of the switching elements Q13 and Q14. A resonant inductor Lr1 and a resonant capacitor Cr1 are connected in series via the primary winding n1 of the transformer T1 between the high potential side terminal Va1 and the low potential side terminal Vb1. Here, a primary inductance Lm1 is connected in parallel to the primary winding n1 of the transformer T1.

  The resonance circuit 22a is provided with a resonance inductor Lr2 and a resonance capacitor Cr2, and is provided with a high potential side terminal Va2 and a low potential side terminal Vb2. The high potential side terminal Va2 is connected to the connection point of the switching elements Q21 and Q22, and the low potential side terminal Vb2 is connected to the connection point of the switching elements Q23 and Q24. A resonant inductor Lr2 and a resonant capacitor Cr2 are connected in series via the primary winding n1 of the transformer T2 between the high potential side terminal Va2 and the low potential side terminal Vb2. Here, a primary inductance Lm2 is connected in parallel to the primary winding n1 of the transformer T2.

  The rectifier circuit 13a is provided with rectifier diodes D11 and D12. The cathode of the rectifier diode D11 is connected to one end of the secondary winding n3 of the transformer T1, and the anode of the rectifier diode D11 is connected to the other end of the secondary winding n3 of the transformer T1 via the output capacitor Co. It is connected. The cathode of the rectifier diode D12 is connected to one end of the secondary winding n2 of the transformer T1, and the anode of the rectifier diode D12 is connected to the anode of the rectifier diode D11.

  The rectifier circuit 23a is provided with rectifier diodes D21 and D22. The cathode of the rectifier diode D21 is connected to one end of the secondary winding n3 of the transformer T2, and the anode of the rectifier diode D21 is connected to the other end of the secondary winding n3 of the transformer T2 via the output capacitor Co. It is connected. The cathode of the rectifier diode D22 is connected to one end of the secondary winding n2 of the transformer T2, and the anode of the rectifier diode D22 is connected to the anode of the rectifier diode D21.

  Further, current sensors S1 and S2 are connected in series to the resonant inductors Lr1 and Lr2, respectively. The outputs of the current sensors S1, S2 are connected to the phase shift control units 11, 21. For example, a current transformer can be used as the current sensors S1 and S2.

  The direct current generated by the direct current power source Ei is applied to the orthogonal transformation circuits 11a and 21a, respectively. Further, primary resonance currents iLr1 and iLr2 flowing through the resonant inductors Lr1 and Lr2, respectively, are detected by the current sensors S1 and S2, and input to the phase shift control units 11 and 21, respectively.

Then, the phase shift control unit 11 controls the switching elements Q11 to Qcom1 while controlling the commutation period tcom1 that bypasses the DC power supply Ei so that the primary resonance currents iLr1 and iLr2 flowing through the resonance inductors Lr1 and Lr2 respectively coincide with each other. By turning on / off Q14 at a constant period T, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 12a.
Here, when the switching elements Q11 to Q14 are turned on / off at a constant period T, the phase shift control unit 11 prevents the voltage generated by the DC power supply Ei from being applied to the resonance circuit 12a, and the DC power supply. The period in which the voltage generated by Ei is applied to the resonance circuit 12a can be alternately repeated.

  When the voltage generated by the DC power supply Ei is not applied to the resonance circuit 12a, the phase shift control unit 11 may turn on the switching elements Q11 and Q13 after turning off the switching elements Q12 and Q14. it can. Alternatively, the switching elements Q12 and Q14 can be turned on after the switching elements Q11 and Q13 are turned off.

  When the voltage generated by the DC power supply Ei is applied to the resonance circuit 12a, the phase shift control unit 11 turns off the switching elements Q12 and Q13 and then turns on the switching elements Q11 and Q14. be able to. Alternatively, the switching elements Q12 and Q13 can be turned on after the switching elements Q11 and Q14 are turned off. For example, the phase shift control unit 11 performs on / off control of the switching elements Q11 and Q12 so that the phase difference is 180 degrees and the duty ratio is 50%, and the phase difference is 180 degrees and the duty ratio is 50%. The switching elements Q13 and Q14 can be controlled on / off so that the phase is shifted within a range larger than 0 degree and smaller than 180 degrees with respect to the switching elements Q11 and Q12.

  When the rectangular wave generated by the orthogonal transformation circuit 11a is input to the resonance circuit 12a, the rectangular wave is output to the transformer T1 while being resonated by the resonance circuit 12a. When the resonance current resonated by the resonance circuit 12a is input to the transformer T1, the voltage is stepped up or stepped down according to the winding ratio between the primary winding n1 of the transformer T1 and the secondary windings n2 and n3. Are input to the rectifier circuit 13a. In the rectifier circuit 13a, the alternating current output from the transformer T1 is rectified by the rectifier diodes D11 and D12 and applied to the output capacitor Co.

Further, the phase shift control unit 21 controls the switching elements Q21 to Qcom2 while controlling the commutation period tcom2 that bypasses the DC power supply Ei so that the primary resonance currents iLr1 and iLr2 flowing through the resonance inductors Lr1 and Lr2 respectively coincide with each other. By turning Q24 on / off at a constant period T, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 22a.
Here, when the switching elements Q21 to Q24 are turned on / off at a constant period T, the phase shift control unit 21 prevents the voltage generated by the DC power supply Ei from being applied to the resonance circuit 22a, and the DC power supply. The period in which the voltage generated by Ei is applied to the resonance circuit 22a can be alternately repeated.

  When the voltage generated by the DC power supply Ei is not applied to the resonance circuit 22a, the phase shift control unit 21 may turn on the switching elements Q21 and Q23 after turning off the switching elements Q22 and Q24. it can. Alternatively, the switching elements Q22 and Q24 can be turned on after the switching elements Q21 and Q23 are turned off.

  When the voltage generated by the DC power source Ei is applied to the resonance circuit 22a, the phase shift control unit 21 turns off the switching elements Q22 and Q23 and then turns on the switching elements Q21 and Q24. be able to. Alternatively, the switching elements Q22 and Q23 can be turned on after the switching elements Q21 and Q24 are turned off. For example, the phase shift control unit 21 performs on / off control of the switching elements Q21 and Q22 so that the phase difference is 180 degrees and the duty ratio is 50%, and the phase difference is 180 degrees and the duty ratio is 50%. The switching elements Q23 and Q24 can be controlled on / off so that the phase is shifted within a range larger than 0 degree and smaller than 180 degrees with respect to the switching elements Q21 and Q22.

  When the rectangular wave generated by the orthogonal transformation circuit 21a is input to the resonance circuit 22a, the rectangular wave is output to the transformer T2 while being resonated by the resonance circuit 22a. When the resonance current resonated by the resonance circuit 22a is input to the transformer T2, the voltage is stepped up or stepped down according to the winding ratio between the primary winding n1 of the transformer T2 and the secondary windings n2 and n3. Are input to the rectifier circuit 23a. In the rectifier circuit 23a, the alternating current output from the transformer T2 is rectified by the rectifier diodes D21 and D22 and applied to the output capacitor Co.

  Here, in the phase difference setting unit 31, the phase difference θ is set during the switching control by the phase shift control units 11 and 21, and the phase difference θ is generated in the current rectified by the rectifier circuits 13a and 23a, respectively. To do. When the current rectified by the rectifier circuits 13a and 23a is applied to the output capacitor Co, the current is smoothed and supplied to the load resistor RL.

  This makes it possible to supply current from the plurality of converters Conv11, Conv21 to the output capacitor Co while allowing the phases of the currents supplied from the converters Conv11, Conv21 to the output capacitor Co to be different from each other. The peak value of the current supplied from the converters Conv11 and Conv21 to the output capacitor Co can be adjusted while maintaining the frequency constant. For this reason, even when there are variations and fluctuations in the characteristics of the circuit components, the peak value of the current supplied from the converters Conv11 and Conv21 to the output capacitor Co can be made uniform, and the ripple current of the output capacitor Co is reduced. Therefore, the capacity of the output capacitor Co can be reduced, and the DCDC converter can be reduced in size and price.

  In the above-described embodiment, the method of detecting the primary resonant currents iLr1 and iLr2 flowing in the resonant inductors Lr1 and Lr2 in order to control the conduction periods ton1 and ton2, respectively, has been described. However, the rectifier diodes D11 and D12 respectively The conduction period ton1 may be controlled based on the combined value of the flowing currents, and the conduction period ton2 may be controlled based on the combined values of the currents flowing through the rectifier diodes D21 and D22.

  Alternatively, the conduction period ton1 is controlled based on the product of the terminal voltage Vo of the load resistance RL and the primary resonance current iLr1, and based on the product of the terminal voltage Vo of the load resistance RL and the primary resonance current iLr2. The conduction period ton2 may be controlled, or the conduction period ton1 is controlled based on the product of the voltage Vo between the terminals of the load resistor RL and the combined value of the currents flowing through the rectifier diodes D11 and D12, and the load resistance The conduction period ton2 may be controlled based on the product of the inter-terminal voltage Vo of the RL and the combined value of the currents flowing through the rectifier diodes D21 and D22.

  FIG. 2 is a diagram showing the relationship between the on / off timing of switching elements Q11 to Q14 and Q21 to Q24 in FIG. 1, and the voltage between Va1-Vb1 and the voltage between Va2-Vb2.

  At time t1 in FIG. 2, the switching element Q13 is turned off, the switching element Q14 is turned on, the switching element Q11 is turned on, and the switching element Q12 is turned off, so that the DC power supply Ei → switching element Q11 → resonance inductor Lr1 → transformer T1. Current flows through a path of primary winding n1 → resonance capacitor Cr1 → switching element Q14 → DC power supply Ei, and between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a is a DC power supply Ei. The generated direct current is applied.

  Next, at time t2, switching element Q13 is turned on and switching element Q14 is turned off while switching element Q11 is turned on and switching element Q12 is turned off, so that switching element Q13 → switching element Q11 → resonance inductor Lr1 → transformer T1. Since the current flows through the path of the primary winding n1 → resonance capacitor Cr1 → switching element Q13 and the DC power supply Ei is bypassed, there is a gap between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a. , 0V is applied.

  When 0 V is applied between the high-potential side terminal Va1 and the low-potential side terminal Vb1 of the resonance circuit 12a, the amount of power supplied to the rectifier circuit 13a is reduced while continuing the resonance operation in the resonance circuit 12a. Therefore, the output voltage of the converter Conv11 can be reduced.

  Next, at time t3, the switching element Q13 is turned on, the switching element Q14 is turned off, the switching element Q11 is turned off, and the switching element Q12 is turned on, so that the DC power source Ei → switching element Q13 → resonance capacitor Cr1 → transformer T1. Current flows through a path of primary winding n1 → resonance inductor Lr1 → switching element Q12 → DC power supply Ei, and between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a, the DC power supply Ei The generated direct current is inverted and applied.

  Next, at time t4, switching element Q11 is turned off, switching element Q12 is kept on, switching element Q13 is turned off, and switching element Q14 is turned on, so that switching element Q12 → switching element Q14 → resonance capacitor Cr1 → transformer T1. Current flows through the path of the primary winding n1 → resonance inductor Lr1 → switching element Q12 and the DC power supply Ei is bypassed, and therefore, between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a. , 0V is applied. Then, by repeating the above operation as one cycle T, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 12a.

  Here, a period in which the voltage generated by the DC power supply Ei is not applied to the resonance circuit 12a is a commutation period tcom1, and a period in which the voltage generated by the DC power supply Ei is applied to the resonance circuit 12a is a conduction period ton1. It is possible to set ton1 + tcom1 = T / 2. Then, the phase shift control unit 11 controls the conduction period ton1 so that the primary resonance currents iLr1 and iLr2 flowing through the resonance inductors Lr1 and Lr2 respectively coincide with each other, thereby causing variations or fluctuations in characteristics of circuit components. The current supplied from the converters Conv11 and Conv21 to the output capacitor Co can be made uniform, and the ripple current of the output capacitor Co can be reduced.

  Further, it is assumed that the times t1 ′ to t8 ′ are delayed from the times t1 to t8 by the time of the phase difference θ. At time t1 ′, the switching element Q23 is turned off, the switching element Q24 is kept on, the switching element Q21 is turned on, and the switching element Q22 is turned off, so that the DC power supply Ei → switching element Q21 → resonance inductor Lr2 → transformer T2 Current flows through a path of primary winding n1 → resonance capacitor Cr2 → switching element Q24 → DC power supply Ei, and between the high potential side terminal Va2 and the low potential side terminal Vb2 of the resonance circuit 22a is a DC power supply Ei. The generated direct current is applied.

  Next, at time t2 ′, switching element Q23 is turned on and switching element Q24 is turned off while switching element Q21 is turned on and switching element Q22 is turned off, so that switching element Q23 → switching element Q21 → resonance inductor Lr2 → transformer. Since current flows through the path T1 primary winding n1 → resonance capacitor Cr2 → switching element Q23 and the DC power supply Ei is bypassed, the resonance circuit 22a has a high potential side terminal Va2 and a low potential side terminal Vb2. Is applied with 0V.

  When 0 V is applied between the high-potential side terminal Va2 and the low-potential side terminal Vb2 of the resonance circuit 22a, the amount of power supplied to the rectifier circuit 23a is reduced while continuing the resonance operation in the resonance circuit 22a. Therefore, the output voltage of the converter Conv21 can be reduced.

  Next, at time t3 ′, the switching element Q21 is turned off and the switching element Q22 is turned on while the switching element Q23 is turned on and the switching element Q24 is turned off, so that the DC power supply Ei → switching element Q23 → resonance capacitor Cr2 → transformer. A current flows through the path T1 primary winding n1 → resonant inductor Lr2 → switching element Q22 → DC power supply Ei, and the DC power supply Ei is connected between the high potential side terminal Va2 and the low potential side terminal Vb2 of the resonance circuit 22a. The generated direct current is inverted and applied.

  Next, at time t4 ′, the switching element Q21 is turned off, the switching element Q22 is turned on, the switching element Q23 is turned off, and the switching element Q24 is turned on, so that the switching element Q22 → switching element Q24 → resonance capacitor Cr2 → transformer. Since current flows through the path T1 primary winding n1 → resonant inductor Lr2 → switching element Q22 and the DC power supply Ei is bypassed, the resonance circuit 22a has a high potential side terminal Va2 and a low potential side terminal Vb2. Is applied with 0V. Then, by repeating the above operation as one cycle T, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 22a.

  Here, a period in which the voltage generated by the DC power supply Ei is not applied to the resonance circuit 22a is a commutation period tcom2, and a period in which the voltage generated by the DC power supply Ei is applied to the resonance circuit 22a is a conduction period ton2. It can be ton2 + tcom2 = T / 2. Then, the phase shift control unit 21 controls the conduction period ton2 so that the primary resonance currents iLr1 and iLr2 flowing through the resonance inductors Lr1 and Lr2 respectively coincide with each other, thereby causing variations or fluctuations in characteristics of circuit components. The current supplied from the converters Conv11 and Conv21 to the output capacitor Co can be made uniform, and the ripple current of the output capacitor Co can be reduced.

  For example, when the value of the primary resonance current iLr1 is smaller than the value of the primary resonance current iLr2, the conduction period ton1 is made larger than the conduction period ton2, and the value of the primary resonance current iLr1 is equal to the primary resonance current iLr2. When larger than the value, the conduction period ton1 can be made shorter than the conduction period ton2. In particular, when the load is heavy, it is possible to effectively reduce the ripple current of the output capacitor Co by controlling the conduction periods ton1 and ton2. On the other hand, since the current flowing through the output capacitor Co is small when the input voltage is high and the load is light, the ripple current of the output capacitor Co can be reduced even when only one of the converters Conv11 and Conv21 is used.

FIG. 3 is a diagram showing the relationship between the switching frequency and voltage gain of converter Conv11 in FIG. 1 when conduction angle D is changed.
In FIG. 3, when the conduction angle D is ton1 / T, it can be seen that the voltage gain is reduced by reducing the conduction angle D even when the switching frequency of the switching elements Q11 to Q14 is constant.

  For example, when the voltage gain is decreased from 1 to 0.8, it is necessary to increase from 95 kHz to 280 kHz if the control is based on the switching frequency, whereas 0.5 to 0.1 if the control is based on the conduction angle D. You can see that

  Similarly, for the converter Conv21, when the conduction angle D is ton2 / T, the voltage gain can be reduced by reducing the conduction angle D even when the switching frequency of the switching elements Q21 to Q24 is constant. .

  FIG. 4A shows the waveforms of the primary resonance current and the transformer excitation current when the conduction periods ton1 and ton2 are matched when the constants of the resonance circuits 12a and 22a are equal between the converters Conv11 and Conv21 of FIG. FIG. 4B is a diagram illustrating waveforms of the transformer secondary current and the output capacitor ripple current at this time.

The primary resonance currents indicate currents iLr1 and iLr2 flowing in the resonance inductors Lr1 and Lr2 in FIG. Further, the transformer excitation current indicates currents iLm1 and iLm2 flowing in the primary inductances Lm1 and Lm2 in FIG. 1, respectively. The transformer secondary current indicates currents id11, id12, id21, and id22 flowing through the rectifier diodes D11, D12, D21, and D22 in FIG. 1, respectively. Further, the output capacitor ripple current indicates the current ir flowing through the output capacitor Co in FIG.
The constants of the converters Conv11 and Conv21 are the same (Lr1 = Lr2 = 16 μH, Lm1 = Lm2 = 80 μH, Cr1 = Cr2 = 150 nF), the phase difference θ is 90 degrees, the input voltage Vin is 375 V, and the switching frequency fsw is 90 kHz. , Ton1 = ton2, and the output voltage Vo was controlled to be 48V.

  In FIGS. 4A and 4B, when the constants of the converters Conv11 and Conv21 are the same, by setting ton1 = ton2, the currents id11, id12, id21 flowing through the rectifier diodes D11, D12, D21, and D22, respectively. The peak value Δid of id22 is equal to 64A, and the ripple Δir of the current flowing through the output capacitor Co can be suppressed to 23A.

FIG. 5A shows the waveforms of the primary resonance current and the transformer excitation current when the conduction periods ton1 and ton2 are matched when the constants of the resonance circuits 12a and 22a are different between the converters Conv11 and Conv21 of FIG. FIG. 5B is a diagram illustrating waveforms of the transformer secondary current and the output capacitor ripple current at this time.
The constants of the converters Conv11 and Conv21 are different (Lr1 = 16 μH, Lr2 = 15.2 μH, Lm1 = Lm2 = 80 μH, Cr1 = Cr2 = 150 nF), the phase difference θ is 90 degrees, the input voltage Vin is 375 V, The switching frequency fsw was set to 90 kHz, ton1 = ton2, and the output voltage Vo was controlled to be 48V.

  In FIGS. 5A and 5B, when the constants of the converters Conv11 and Conv21 are different, assuming that ton1 = ton2, the peak values Δid of the currents id11 and id21 flowing through the rectifier diodes D11 and D21 are 35A and the rectifier diode D12, respectively. The peak value Δid of the currents id12 and id22 flowing through D22 is 102A, and the ripple Δir of the current flowing through the output capacitor Co is increased to 85.

FIG. 6A shows the waveforms of the primary resonance current and the transformer excitation current when the conduction periods ton1 and ton2 are controlled when the constants of the resonance circuits 12a and 22a are different between the converters Conv11 and Conv21 of FIG. FIGS. 6A and 6B are diagrams illustrating waveforms of the transformer secondary current and the output capacitor ripple current at this time.
The constants of the converters Conv11 and Conv21 are different (Lr1 = 16 μH, Lr2 = 15.2 μH, Lm1 = Lm2 = 80 μH, Cr1 = Cr2 = 150 nF), the phase difference θ is 90 degrees, the input voltage Vin is 375 V, The switching frequency fsw was controlled to 90 kHz and the output voltage Vo was 48V. Also, ton1 was controlled to ton1 + Δton1 and ton2 was controlled ton2 + Δton2 so that the currents id11, id12, id21, id22 flowing through the rectifier diodes D11, D12, D21, D22 were equal to each other.

  In FIGS. 6A and 6B, when the constants of the converters Conv11 and Conv21 are different, the ton1 is set so that the currents id11, id12, id21 and id22 flowing through the rectifier diodes D11, D12, D21 and D22 are equal to each other. , Ton2 was able to reduce the ripple Δir of the current flowing through the output capacitor Co to 44.4A.

FIG. 7 is a block diagram showing a schematic configuration of the DCDC converter according to the second embodiment of the present invention.
In FIG. 7, this DCDC converter is provided with converters Conv12 and Conv22 instead of the converters Conv11 and Conv21 of FIG. Here, the converter Conv12 is provided with a resonance circuit 12b instead of the resonance circuit 12a of FIG. Further, the converter Conv22 is provided with a resonance circuit 22b instead of the resonance circuit 22a of FIG.

Here, the resonance circuit 12b is provided with a resonance inductor Lr11 and a resonance capacitor Cr11. A series circuit of a resonant inductor Lr11 and a resonant capacitor Cr11 is connected between the high potential side terminal Va1 and the low potential side terminal Vb1, and a primary inductance Lm1 is connected in parallel to the resonant capacitor Cr11. ing.
The resonance circuit 22b is provided with a resonance inductor Lr21 and a resonance capacitor Cr21. A series circuit of a resonant inductor Lr21 and a resonant capacitor Cr21 is connected between the high potential side terminal Va2 and the low potential side terminal Vb2, and a primary inductance Lm2 is connected in parallel to the resonant capacitor Cr21. ing.

The direct current generated by the direct current power source Ei is applied to the orthogonal transformation circuits 11a and 21a, respectively. Further, the currents output from the resonance circuits 12b and 22b are detected by the current sensors S1 and S2, respectively, and input to the phase shift control units 11 and 21.
The phase shift control unit 11 controls the switching elements Q11 to Q14 at a constant period while controlling the commutation period tcom1 for bypassing the DC power supply Ei so that the currents output from the resonance circuits 12b and 22b coincide with each other. By turning on / off at T, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 12b.

When the rectangular wave generated by the orthogonal transformation circuit 11a is input to the resonance circuit 12b, the rectangular wave is output to the transformer T1 while being resonated by the resonance circuit 12b. When the resonance current resonated by the resonance circuit 12b is input to the transformer T1, the voltage is stepped up or stepped down according to the winding ratio between the primary winding n1 of the transformer T1 and the secondary windings n2 and n3. Are input to the rectifier circuit 13a. In the rectifier circuit 13a, the alternating current output from the transformer T1 is rectified by the rectifier diodes D11 and D12 and applied to the output capacitor Co.
Further, the phase shift control unit 21 controls the switching elements Q21 to Q24 at a constant cycle while controlling the commutation period tcom2 for bypassing the DC power supply Ei so that the currents output from the resonance circuits 12b and 22b coincide with each other. By turning on / off at T, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 22b.

  When the rectangular wave generated by the orthogonal transformation circuit 21a is input to the resonance circuit 22b, the rectangular wave is output to the transformer T2 while being resonated by the resonance circuit 22b. When the resonance current resonated by the resonance circuit 22b is input to the transformer T2, the voltage is stepped up or stepped down according to the winding ratio between the primary winding n1 of the transformer T2 and the secondary windings n2 and n3. Are input to the rectifier circuit 23a. In the rectifier circuit 23a, the alternating current output from the transformer T2 is rectified by the rectifier diodes D21 and D22 and applied to the output capacitor Co. The on / off timings of the switching elements Q11 to Q14 and Q21 to Q24 can be set in the same manner as in FIG.

  Here, in the phase difference setting unit 31, the phase difference θ is set during the switching control by the phase shift control units 11 and 21, and the phase difference θ is generated in the current rectified by the rectifier circuits 13a and 23a, respectively. To do. When the current rectified by the rectifier circuits 13a and 23a is applied to the output capacitor Co, the current is smoothed and supplied to the load resistor RL.

  As a result, even when parallel resonance is performed in the resonance circuits 12b and 22b, the peak value of the current supplied from the converters Conv12 and Conv22 to the output capacitor Co can be made uniform, and the ripple current of the output capacitor Co is reduced. Therefore, the capacity of the output capacitor Co can be reduced, and the DCDC converter can be reduced in size and price.

FIG. 8 is a block diagram showing a schematic configuration of the DCDC converter according to the third embodiment of the present invention.
In FIG. 8, this DCDC converter is provided with converters Conv13 and Conv23 instead of the converters Conv11 and Conv21 of FIG. Here, the converter Conv13 is provided with a rectifier circuit 13c instead of the transformer T1 and the rectifier circuit 13a of FIG. Further, the converter Conv23 is provided with a rectifier circuit 23c instead of the transformer T2 and the rectifier circuit 23a of FIG.

  Here, rectifier diodes D13 to D16 are provided in the rectifier circuit 13c. The rectifier diodes D13 and D15 are connected in series with each other, and the rectifier diodes D14 and D16 are connected in series with each other. The series circuit of rectifier diodes D13 and D15 is connected in parallel to the output capacitor Co, and the series circuit of rectifier diodes D14 and D16 is connected in parallel to the output capacitor Co.

  A resonant inductor Lr1 is connected between the high potential side terminal Va1 and the connection point of the rectifier diodes D13 and D15, and between the low potential side terminal Vb1 and the connection point of the rectifier diodes D14 and D16. The resonance capacitor Cr1 is connected.

  The rectifier circuit 23c is provided with rectifier diodes D23 to D26. The rectifier diodes D23 and D25 are connected in series with each other, and the rectifier diodes D24 and D26 are connected in series with each other. The series circuit of rectifier diodes D23 and D25 is connected in parallel to the output capacitor Co, and the series circuit of rectifier diodes D24 and D26 is connected in parallel to the output capacitor Co.

  A resonant inductor Lr2 is connected between the high potential side terminal Va2 and the connection point of the rectifier diodes D23 and D25, and between the low potential side terminal Vb2 and the connection point of the rectifier diodes D24 and D26. The resonance capacitor Cr2 is connected.

The direct current generated by the direct current power source Ei is applied to the orthogonal transformation circuits 11a and 21a, respectively. Further, currents output from the resonance circuits 12a and 22a are detected by the current sensors S1 and S2, respectively, and input to the phase shift control units 11 and 21.
Then, the phase shift control unit 11 controls the switching elements Q11 to Q14 at a constant cycle while controlling the commutation period tcom1 for bypassing the DC power supply Ei so that the currents output from the resonance circuits 12a and 22a coincide with each other. By turning on / off at T, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 12a.

  When the rectangular wave generated by the orthogonal transformation circuit 11a is input to the resonance circuit 12a, the rectangular wave is input to the rectifier circuit 13c while being resonated by the resonance circuit 12a. In the rectifier circuit 13c, the resonance current output from the resonance circuit 12a is rectified by the rectifier diodes D13 to D16 and applied to the output capacitor Co.

  Further, the phase shift control unit 21 controls the switching elements Q21 to Q24 at a constant cycle while controlling the commutation period tcom2 for bypassing the DC power supply Ei so that the currents output from the resonance circuits 12a and 22a coincide with each other. By turning on / off at T, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 22a.

  When the rectangular wave generated by the orthogonal transformation circuit 21a is input to the resonance circuit 22a, the rectangular wave is output to the rectifier circuit 23c while being resonated by the resonance circuit 22a. In the rectifier circuit 23c, the resonance current output from the resonance circuit 22a is rectified by the rectifier diodes D23 to D26 and applied to the output capacitor Co. The on / off timings of the switching elements Q11 to Q14 and Q21 to Q24 can be set in the same manner as in FIG.

  Here, in the phase difference setting unit 31, the phase difference θ is set during the switching control by the phase shift control units 11 and 21, and the phase difference θ is generated in the current rectified by the rectifier circuits 13c and 23c, respectively. To do. When the current rectified by the rectifier circuits 13c and 23c is applied to the output capacitor Co, the current is smoothed and supplied to the load resistor RL.

  Thereby, even when the transformers T1 and T2 in FIG. 1 are not provided, the peak value of the current supplied from the converters Conv13 and Conv23 to the output capacitor Co can be made uniform, and the ripple current of the output capacitor Co can be reduced. Therefore, the output capacitor Co can be reduced in capacity, and the DCDC converter can be reduced in size and price.

FIG. 9 is a block diagram showing a schematic configuration of the DCDC converter according to the fourth embodiment of the present invention.
In FIG. 9, this DCDC converter includes PWM control units 12 and 22 and a phase difference setting unit 32 instead of the phase shift control units 11 and 21 and the phase difference setting unit 31 of the DCDC converter of FIG. 1. Here, the PWM control unit 12 performs on / off control of the switching elements Q12 and Q14 so as to be alternately turned on with a commutation period tcom1 within one cycle T, and performs the inversion operation of the switching elements Q12 and Q14, respectively. Thus, the switching elements Q11 and Q13 can be controlled on / off.

  Also, the PWM control unit 22 performs on / off control of the switching elements Q22 and Q24 so as to be alternately turned on within the commutation period tcom1 within one cycle T, and performs the inversion operation of the switching elements Q22 and Q24, respectively. The switching elements Q21 and Q23 can be turned on / off. Further, the phase difference setting unit 32 can set the phase difference θ between the switching control by the PWM control unit 12 and the switching control by the PWM control unit 22.

The direct current generated by the direct current power source Ei is applied to the orthogonal transformation circuits 11a and 21a, respectively. The currents output from the resonance circuits 12a and 22a are detected by the current sensors S1 and S2, respectively, and input to the PWM control units 12 and 22.
Then, the PWM control unit 12 controls the switching elements Q11 to Q14 with a certain period T while controlling the commutation period tcom1 for bypassing the DC power supply Ei so that the currents output from the resonance circuits 12a and 22a coincide with each other. By turning on / off at, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 12a.

  When the rectangular wave generated by the orthogonal transformation circuit 11a is input to the resonance circuit 12a, the rectangular wave is output to the transformer T1 while being resonated by the resonance circuit 12a. When the resonance current resonated by the resonance circuit 12a is input to the transformer T1, the voltage is stepped up or stepped down according to the winding ratio between the primary winding n1 of the transformer T1 and the secondary windings n2 and n3. Are input to the rectifier circuit 13a. In the rectifier circuit 13a, the alternating current output from the transformer T1 is rectified by the rectifier diodes D11 and D12 and applied to the output capacitor Co.

  Further, the PWM control unit 22 controls the switching elements Q21 to Q24 with a certain period T while controlling the commutation period tcom2 for bypassing the DC power supply Ei so that the currents output from the resonance circuits 12a and 22a coincide with each other. By turning on / off at, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 22a.

  When the rectangular wave generated by the orthogonal transformation circuit 21a is input to the resonance circuit 22a, the rectangular wave is output to the transformer T2 while being resonated by the resonance circuit 22a. When the resonance current resonated by the resonance circuit 22a is input to the transformer T2, the voltage is stepped up or stepped down according to the winding ratio between the primary winding n1 of the transformer T2 and the secondary windings n2 and n3. Are input to the rectifier circuit 23a. In the rectifier circuit 23a, the alternating current output from the transformer T2 is rectified by the rectifier diodes D21 and D22 and applied to the output capacitor Co.

  Here, in the phase difference setting unit 32, the phase difference θ is set during the switching control by the PWM control units 12 and 22, and the phase difference θ is generated in the current rectified by the rectifier circuits 13a and 23a. . When the current rectified by the rectifier circuits 13a and 23a is applied to the output capacitor Co, the current is smoothed and supplied to the load resistor RL.

FIG. 10 is a diagram showing the relationship between the on / off timing of switching elements Q11 to Q14 and Q21 to Q24 in FIG. 9, and the voltage between Va1 and Vb1 and the voltage between Va2 and Vb2.
At time t1 in FIG. 10, the switching element Q11 is turned on, the switching element Q12 is turned off, the switching element Q13 is turned off, and the switching element Q14 is turned on, so that the DC power supply Ei → switching element Q11 → resonance inductor Lr1 → transformer T1. Current flows through a path of primary winding n1 → resonance capacitor Cr → switching element Q4 → DC power supply Ei, and between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a by a DC power supply Ei. The generated direct current is applied.

  Next, at time t2, switching element Q13 is turned on and switching element Q14 is turned off while switching element Q11 is turned on and switching element Q12 is turned off, so that switching element Q13 → switching element Q11 → resonance inductor Lr1 → transformer T1. Since the current flows through the path of the primary winding n1 → resonance capacitor Cr1 → switching element Q13 and the DC power supply Ei is bypassed, there is a gap between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a. , 0V is applied.

  Next, at time t3, the switching element Q13 is turned on, the switching element Q14 is turned off, the switching element Q11 is turned off, and the switching element Q12 is turned on, so that the DC power source Ei → switching element Q13 → resonance capacitor Cr1 → transformer T1. Current flows through a path of primary winding n1 → resonance inductor Lr1 → switching element Q12 → DC power supply Ei, and between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a, the DC power supply Ei The generated direct current is inverted and applied.

  Next, at time t4, the switching element Q13 is turned on and the switching element Q11 is turned on while the switching element Q14 is turned off, and the switching element Q12 is turned off, so that the switching element Q13 → the switching element Q11 → the resonant inductor Lr1 → the transformer T1. Since the current flows through the path of the primary winding n1 → resonance capacitor Cr1 → switching element Q13 and the DC power supply Ei is bypassed, there is a gap between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a. , 0V is applied. Then, by repeating the above operation as one cycle T, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 12a.

  Further, it is assumed that the times t1 ′ to t8 ′ are delayed from the times t1 to t8 by the time of the phase difference θ. At time t1 ′ in FIG. 10, the switching element Q21 is turned on, the switching element Q22 is turned off, the switching element Q23 is turned off, and the switching element Q24 is turned on, so that the DC power supply Ei → switching element Q21 → resonance inductor Lr2. → Current flows through a path of the primary winding n1 of the transformer T2 → resonance capacitor Cr2 → switching element Q24 → DC power supply Ei, and a DC power supply is connected between the high potential side terminal Va2 and the low potential side terminal Vb2 of the resonance circuit 22a. A direct current generated at Ei is applied.

  Next, at time t2 ′, switching element Q23 is turned on and switching element Q24 is turned off while switching element Q21 is turned on and switching element Q22 is turned off, so that switching element Q23 → switching element Q21 → resonance inductor Lr2 → transformer. Since current flows through the path T1 primary winding n1 → resonance capacitor Cr2 → switching element Q23 and the DC power supply Ei is bypassed, the resonance circuit 22a has a high potential side terminal Va2 and a low potential side terminal Vb2. Is applied with 0V.

  Next, at time t3 ′, the switching element Q21 is turned off and the switching element Q22 is turned on while the switching element Q23 is turned on and the switching element Q24 is turned off, so that the DC power supply Ei → switching element Q23 → resonance capacitor Cr2 → transformer. A current flows through the path T1 primary winding n1 → resonant inductor Lr2 → switching element Q22 → DC power supply Ei, and the DC power supply Ei is connected between the high potential side terminal Va2 and the low potential side terminal Vb2 of the resonance circuit 22a. The generated direct current is inverted and applied.

  Next, at time t4 ′, the switching element Q23 is turned on and the switching element Q22 is turned off while the switching element Q23 is turned on and the switching element Q24 is turned off, so that the switching element Q23 → the switching element Q21 → the resonant inductor Lr2 → the transformer. Since current flows through the path T1 primary winding n1 → resonance capacitor Cr2 → switching element Q23 and the DC power supply Ei is bypassed, the resonance circuit 22a has a high potential side terminal Va2 and a low potential side terminal Vb2. Is applied with 0V. Then, by repeating the above operation as one cycle T, the direct current applied from the direct current power source Ei is converted into a rectangular wave and output to the resonance circuit 22a.

  Thereby, even when the duty ratio of the switching elements Q12, Q14, Q22, Q24 is made smaller than 50%, the peak value of the current supplied from the converters Conv13, Conv23 to the output capacitor Co can be made uniform, and the output Since the ripple current of the capacitor Co can be reduced, the capacity of the output capacitor Co can be reduced, and the size and price of the DCDC converter can be reduced.

FIG. 11 is a diagram showing the relationship between the on / off timings of the switching elements Q11 to Q14 and Q21 to Q24 in FIG. 9 according to the fifth embodiment of the present invention, and the voltages between Va1-Vb1 and Va2-Vb2. is there.
At time t1 in FIG. 11, the switching element Q11 is turned off, the switching element Q12 is turned on, the switching element Q13 is turned on, and the switching element Q14 is turned off, so that the DC power supply Ei → switching element Q13 → resonance capacitor Cr1 → transformer T1. Current flows through a path of primary winding n1 → resonance inductor Lr1 → switching element Q12 → DC power supply Ei, and between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a, the DC power supply Ei The generated direct current is applied.

  Next, at time t2, switching element Q11 is turned off, switching element Q12 is kept on, switching element Q13 is turned off, and switching element Q14 is turned on, so that switching element Q12 → switching element Q14 → resonance capacitor Cr1 → transformer T1. Current flows through the path of the primary winding n1 → resonance inductor Lr1 → switching element Q12 and the DC power supply Ei is bypassed, and therefore, between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a. , 0V is applied.

  Next, at time t3, switching element Q13 is turned off, switching element Q14 is kept on, switching element Q11 is turned on, and switching element Q12 is turned off, so that DC power supply Ei → switching element Q11 → resonance inductor Lr1 → transformer T1. Current flows through a path of primary winding n1 → resonance capacitor Cr1 → switching element Q14 → DC power supply Ei, and between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a is a DC power supply Ei. The generated direct current is inverted and applied.

  Next, at time t4, switching element Q13 is turned off, switching element Q14 is kept on, switching element Q11 is turned off, and switching element Q12 is turned on, so that switching element Q12 → switching element Q14 → resonance capacitor Cr1 → transformer T1. Current flows through the path of the primary winding n1 → resonance inductor Lr1 → switching element Q12 and the DC power supply Ei is bypassed, and therefore, between the high potential side terminal Va1 and the low potential side terminal Vb1 of the resonance circuit 12a. , 0V is applied. Then, by repeating the above operation as one cycle T, the direct current applied from the direct current power source Ei is converted into alternating current and output to the resonance circuit 12a.

  Further, it is assumed that the times t1 ′ to t8 ′ are delayed from the times t1 to t8 by the time of the phase difference θ. Then, at time t1 ′ in FIG. 11, the switching element Q21 is turned off, the switching element Q22 is kept on, and the switching element Q23 is turned on and the switching element Q24 is turned off, so that the DC power supply Ei → switching element Q23 → resonance capacitor Cr2 → Current flows through a path of the primary winding n1 of the transformer T2 → resonance inductor Lr2 → switching element Q22 → DC power supply Ei, and a DC power supply is connected between the high potential side terminal Va2 and the low potential side terminal Vb1 of the resonance circuit 22a. A direct current generated at Ei is applied.

  Next, at time t2 ′, switching element Q21 is turned off, switching element Q22 is kept on, switching element Q23 is turned off, and switching element Q24 is turned on, so that switching element Q22 → switching element Q24 → resonance capacitor Cr2 → transformer. Since current flows through the path T1 primary winding n1 → resonant inductor Lr2 → switching element Q22 and the DC power supply Ei is bypassed, the resonance circuit 22a has a high potential side terminal Va2 and a low potential side terminal Vb2. Is applied with 0V.

  Next, at time t3 ′, the switching element Q23 is turned off, the switching element Q24 is turned on, the switching element Q21 is turned on, and the switching element Q22 is turned off, so that the DC power supply Ei → switching element Q21 → resonance inductor Lr2 → transformer. A current flows through a path of T2 primary winding n1 → resonance capacitor Cr2 → switching element Q24 → DC power supply Ei, and the DC power supply Ei is connected between the high potential side terminal Va2 and the low potential side terminal Vb2 of the resonance circuit 22a. The generated direct current is inverted and applied.

  Next, at time t4 ′, the switching element Q23 is turned off and the switching element Q22 is turned on while the switching element Q23 is turned off and the switching element Q24 is turned on, so that the switching element Q22 → switching element Q24 → resonance capacitor Cr2 → transformer Since current flows through the path T1 primary winding n1 → resonant inductor Lr2 → switching element Q22 and the DC power supply Ei is bypassed, the resonance circuit 22a has a high potential side terminal Va2 and a low potential side terminal Vb2. Is applied with 0V. Then, by repeating the above operation as one cycle T, the direct current applied from the direct current power source Ei is converted into alternating current and output to the resonance circuit 22a.

  Thereby, even when the duty ratio of the switching elements Q11, Q13, Q21, Q23 is made smaller than 50%, the peak value of the current supplied from the converters Conv13, Conv23 to the output capacitor Co can be made uniform, and the output Since the ripple current of the capacitor Co can be reduced, the capacity of the output capacitor Co can be reduced, and the size and price of the DCDC converter can be reduced.

  In the fourth and fifth embodiments described above, the method of using a series resonant circuit as the resonant circuits 12a and 22a has been described. However, as shown in FIG. 7, the resonant circuits 12a and 22a have parallel resonance. A circuit may be used.

  In the fourth and fifth embodiments described above, the method of connecting the transformers T1 and T2 between the resonant circuits 12a and 22a and the rectifier circuits 13a and 23a has been described, but as shown in FIG. In addition, the resonant circuits 12a and 22a and the rectifier circuits 13a and 23a may be directly connected without using the transformers T1 and T2.

  In the first embodiment, the second embodiment, the fourth embodiment, and the fifth embodiment, the method using the center tap method as the rectifier circuits 13a and 23 has been described. However, the full wave rectification method may be used. Good.

  In the above-described embodiment, the on / off states of the switching elements Q11 and Q12 are simply reversed with each other, the on / off states of the switching elements Q13 and Q14 are simply reversed with each other, and the on / off states of the switching elements Q21 and Q22 are mutually switched. The method of simply inverting and switching the switching elements Q23 and Q24 on and off with respect to each other has been described. However, in order to prevent a through current from flowing, a dead time is provided on the switching elements Q11 and Q12. Alternatively, a dead time may be provided to turn on / off the switching elements Q13 and Q14, or a dead time may be provided to turn on / off the switching elements Q21 and Q22. Dead data on / off of Q23 and Q24 It may be provided free.

  In the above-described embodiment, the method of connecting the two converters Conv11 and Conv21 in parallel to the output capacitor Co has been described. However, N (N is an integer of 2 or more) converters for the output capacitor Co. May be connected in parallel. In this case, the phase difference θ of the switching control between the N converters is preferably set to 180 / n degrees (1 / 2n * T period). Here, by increasing the number N of converters connected in parallel to the output capacitor Co, the ripple of the current flowing through the output capacitor Co can be further reduced.

  Further, the DCDC converter described above is used for a switching power source that performs power conversion by turning on / off a switching element, an uninterruptible power supply device that shifts to backup power from a battery when an abnormality occurs in an AC input, and the like. be able to.

It is a block diagram showing a schematic structure of a DCDC converter concerning a 1st embodiment of the present invention. It is a figure which shows the relationship between the ON / OFF timing of switching element Q11-Q14 of FIG. 1, and the voltage between Va1-Vb1, and the voltage between Va2-Vb2. It is a figure which shows the relationship between the switching frequency and converter gain of converter Conv11 of FIG. 1 when the conduction angle D is changed. FIG. 2 is a diagram showing waveforms of a primary resonance current and a transformer excitation current when conduction periods ton1 and ton2 are matched when the constants of resonance circuits 12a and 22a are equal between converters Conv11 and Conv21 of FIG. FIG. 2 is a diagram illustrating waveforms of a transformer secondary current and an output capacitor ripple current when conduction periods ton1 and ton2 are matched when the constants of resonance circuits 12a and 22a are equal between converters Conv11 and Conv21 of FIG. FIG. 2 is a diagram illustrating waveforms of a primary resonance current and a transformer excitation current when conduction periods ton1 and ton2 are matched when the constants of resonance circuits 12a and 22a are different between converters Conv11 and Conv21 of FIG. FIG. 7 is a diagram illustrating waveforms of a transformer secondary current and an output capacitor ripple current when conduction periods ton1 and ton2 are matched when the constants of resonance circuits 12a and 22a are different between converters Conv11 and Conv21 of FIG. FIG. 2 is a diagram illustrating waveforms of a primary resonance current and a transformer excitation current when the conduction periods ton1 and ton2 are controlled when the constants of the resonance circuits 12a and 22a are different between the converters Conv11 and Conv21 of FIG. FIG. 2 is a diagram illustrating waveforms of a transformer secondary current and an output capacitor ripple current when the conduction periods ton1 and ton2 are controlled when the constants of the resonance circuits 12a and 22a are different between the converters Conv11 and Conv21 of FIG. It is a block diagram which shows schematic structure of the DCDC converter which concerns on 2nd Embodiment of this invention. It is a block diagram which shows schematic structure of the DCDC converter which concerns on 3rd Embodiment of this invention. It is a block diagram which shows schematic structure of the DCDC converter which concerns on 4th Embodiment of this invention. It is a figure which shows the relationship of the ON / OFF timing of switching element Q11-Q14 of FIG. 9, Q21-Q24, the voltage between Va1-Vb1, and the voltage between Va2-Vb2. It is a figure which shows the on / off timing of the switching elements Q11-Q14 of FIG. 9, and the voltage between Va1-Vb1 and the voltage between Va2-Vb2 of FIG. 9 which concerns on 5th Embodiment of this invention.

Explanation of symbols

Conv11, Conv21, Conv12, Conv22, Conv13, Conv23 Converter Ei DC power supply Cin Input capacitor Q11-Q14, Q21-Q24 Switching elements D11, D12, D21, D22 Rectifier diodes Dq11-Dq14, Dq21-Dq24 Diodes Cq11-Cq14, Cq11-Cq14 Cq24 capacitor Lr1, Lr2, Lr11, Lr21 Resonant inductor Cr1, Cr2, Cr11, Cr21 Resonant capacitor T1, T2 Transformer Lm1, Lm2 Primary inductance n1 Primary winding n2, n3 Secondary winding Co Output capacitor RL Load resistance S1, S2 Current Sensor 11a, 21a Orthogonal transformation circuit 12a, 22a, 12b, 22b Resonant circuit 13a, 23a, 13c, 23c Rectifier circuit 1 , 21 phase-shift control unit 12, 22 PWM control section 31 phase difference setting unit

Claims (7)

A first orthogonal transform unit that transforms a direct current into a rectangular wave based on a switching operation of the first switching element group;
A first resonance circuit that resonates the rectangular wave output from the first orthogonal transform unit;
A first rectification unit for rectifying a resonance current resonated in the first resonance circuit;
The switching operation of the first switching element group is controlled so that the direct current is applied to the first resonance circuit while the polarity is alternately inverted, and the polarity of the direct current applied to the first resonance circuit A first switching control unit for controlling a switching operation of the first switching element group so as to bypass application of the direct current to the first resonance circuit during a period during which
A second orthogonal transform unit that transforms direct current into a rectangular wave based on the switching operation of the second switching element group;
A second resonance circuit for resonating the rectangular wave output from the second orthogonal transform unit;
A second rectification unit for rectifying a resonance current resonated by the second resonance circuit;
The switching operation of the second switching element group is controlled so that the DC is applied to the second resonance circuit while the polarity is alternately inverted, and the polarity of the DC applied to the second resonance circuit A second switching control unit that controls a switching operation of the second switching element group so as to bypass application of the direct current to the second resonance circuit during a period during which
A phase difference setting unit that sets a phase difference between the switching control by the first switching control unit and the switching control by the second switching control unit;
A DCDC converter comprising: an output capacitor to which an output from the first rectifier and an output from the second rectifier are input in parallel. A first orthogonal transform unit that transforms a direct current into a rectangular wave based on a switching operation of the first switching element group;
A first resonance circuit that resonates the rectangular wave output from the first orthogonal transform unit;
A first transformer for transforming a resonance current resonated by the first resonance circuit;
A first rectifier that rectifies the resonant current transformed by the first transformer;
The switching operation of the first switching element group is controlled so that the direct current is applied to the first resonance circuit while the polarity is alternately inverted, and the polarity of the direct current applied to the first resonance circuit A first switching control unit for controlling a switching operation of the first switching element group so as to bypass application of the direct current to the first resonance circuit during a period during which
A second orthogonal transform unit that transforms direct current into a rectangular wave based on the switching operation of the second switching element group;
A second resonance circuit for resonating the rectangular wave output from the second orthogonal transform unit;
A second transformer for transforming a resonance current resonated by the second resonance circuit;
A second rectifier that rectifies the resonant current transformed by the second transformer;
The switching operation of the second switching element group is controlled so that the DC is applied to the second resonance circuit while the polarity is alternately inverted, and the polarity of the DC applied to the second resonance circuit A second switching control unit that controls a switching operation of the second switching element group so as to bypass application of the direct current to the second resonance circuit during a period during which
A phase difference setting unit that sets a phase difference between the switching control by the first switching control unit and the switching control by the second switching control unit;
A DCDC converter comprising: an output capacitor to which an output from the first rectifier and an output from the second rectifier are input in parallel. The first switching element group includes:
A first switching element connected between the positive electrode side of the direct current and the high potential side of the first resonance circuit;
A second switching element connected between the negative electrode side of the direct current and the high potential side of the first resonance circuit;
A third switching element connected between the positive electrode side of the direct current and the low potential side of the first resonance circuit;
A fourth switching element connected between the negative electrode side of the direct current and the low potential side of the first resonance circuit;
The second switching element group includes:
A fifth switching element connected between the positive electrode side of the direct current and the high potential side of the second resonance circuit;
A sixth switching element connected between the negative electrode side of the direct current and the high potential side of the second resonance circuit;
A seventh switching element connected between the positive electrode side of the direct current and the low potential side of the second resonance circuit;
An eighth switching element connected between the negative electrode side of the direct current and the low potential side of the second resonance circuit;
The first switching control unit performs on / off control of the first switching element and the second switching element so that the phase difference is 180 degrees and the duty ratio is 50%, and the phase difference is 180 degrees. And the duty ratio is 50% and the third switching element and the second switching element are shifted in phase within a range larger than 0 degree and smaller than 180 degrees with respect to the first switching element and the second switching element. ON / OFF control of the fourth switching element,
The second switching control unit performs on / off control of the fifth switching element and the sixth switching element so that the phase difference is 180 degrees and the duty ratio is 50%, and the phase difference is 180 degrees. The seventh switching element and the fifth switching element and the sixth switching element have a duty ratio of 50% and are out of phase with respect to the fifth switching element and the sixth switching element within a range larger than 0 degree and smaller than 180 degrees. ON / OFF control of the eighth switching element,
The phase difference setting unit sets the phase difference between the switching control by the first switching control unit and the switching control by the second switching control unit to 90 degrees. The DCDC converter described in 1. The first switching element group includes:
A first switching element connected between the positive electrode side of the direct current and the high potential side of the first resonance circuit;
A second switching element connected between the negative electrode side of the direct current and the high potential side of the first resonance circuit;
A third switching element connected between the positive electrode side of the direct current and the low potential side of the first resonance circuit;
A fourth switching element connected between the negative electrode side of the direct current and the low potential side of the first resonance circuit;
The second switching element group includes:
A fifth switching element connected between the positive electrode side of the direct current and the high potential side of the second resonance circuit;
A sixth switching element connected between the negative electrode side of the direct current and the high potential side of the second resonance circuit;
A seventh switching element connected between the positive electrode side of the direct current and the low potential side of the second resonance circuit;
An eighth switching element connected between the negative electrode side of the direct current and the low potential side of the second resonance circuit;
The first switching control unit performs on / off control of the second switching element and the fourth switching element so as to be alternately turned on at predetermined time intervals within one cycle, and further, On / off control of the first switching element and the third switching element so as to perform inversion operations of the switching element and the fourth switching element, respectively,
The second switching control unit performs on / off control of the sixth switching element and the eighth switching element so that the sixth switching element and the eighth switching element are alternately turned on at predetermined time intervals within one cycle, and the sixth switching element On / off control of the fifth switching element and the seventh switching element so as to perform inversion operations of the switching element and the eighth switching element, respectively,
The phase difference setting unit sets the phase difference between the switching control by the first switching control unit and the switching control by the second switching control unit to 90 degrees. The DCDC converter described in 1. The first switching element group includes:
A first switching element connected between the positive electrode side of the direct current and the high potential side of the first resonance circuit;
A second switching element connected between the negative electrode side of the direct current and the high potential side of the first resonance circuit;
A third switching element connected between the positive electrode side of the direct current and the low potential side of the first resonance circuit;
A fourth switching element connected between the negative electrode side of the direct current and the low potential side of the first resonance circuit;
The second switching element group includes:
A fifth switching element connected between the positive electrode side of the direct current and the high potential side of the second resonance circuit;
A sixth switching element connected between the negative electrode side of the direct current and the high potential side of the second resonance circuit;
A seventh switching element connected between the positive electrode side of the direct current and the low potential side of the second resonance circuit;
An eighth switching element connected between the negative electrode side of the direct current and the low potential side of the second resonance circuit;
The first switching control unit performs on / off control of the first switching element and the third switching element so as to be alternately turned on at predetermined time intervals within one period, and further, On / off control of the second switching element and the fourth switching element so as to perform the inversion operations of the switching element and the third switching element, respectively,
The second switching control unit performs on / off control of the fifth switching element and the seventh switching element so as to be alternately turned on at predetermined time intervals within one cycle, and further On / off control of the sixth switching element and the eighth switching element so as to perform inversion operations of the switching element and the seventh switching element, respectively,
The phase difference setting unit sets the phase difference between the switching control by the first switching control unit and the switching control by the second switching control unit to 90 degrees. The DCDC converter described in 1. An AC / DC conversion circuit for converting AC to DC,
A switching power supply comprising: the DCDC converter according to any one of claims 1 to 5, wherein the DCDC output from the AC / DC converter circuit is stepped up or stepped down and output. DCDC converter according to any one of claims 1 to 5,
A battery for storing the direct current output from the DCDC converter;
An uninterruptible power supply comprising an inverter that converts direct current to alternating current.

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