JP2017123710A - Non-insulation type step-up switching power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-insulation type step-up switching power supply device capable of effectively reducing a loss generated at switching by adding an extremely simple circuit.SOLUTION: A non-insulation type step-up switching power supply device comprises: a choke coil L1 and a rectification diode D1 series-connected between input/output terminals; a main switching element Qm connected between their connection point and the ground; and a capacitor Co connected at a cathode side of the rectification diode, and that smooths a step-up voltage generated by connection and disconnection of the main switching element. A partial resonance circuit that supplies a reverse current to the main switching element at turn-on of the main switching element is parallel-connected. The partial resonance circuit is configured by: a first series circuit parallel-connected with the main switching element and that includes a first resonance diode D2 and a second capacitor Cs; and a second series circuit parallel-connected with the second capacitor and that includes a second resonance diode D3, a reactor L2, and a sub switching element Qs.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-insulated step-up switching power supply device.

Patent Documents 1 and 2 disclose a non-insulated step-up switching power supply device.
As shown in FIG. 10, the conventional non-insulated step-up switching power supply device includes a choke coil L1 and a rectifier diode D1 connected in series between input and output terminals, a connection point between the choke coil L1 and the rectifier diode D1, and a ground. And a capacitor C0 that is connected to the cathode side of the rectifier diode D1 and smoothes the boosted voltage generated when the main switching element Qm is intermittently connected. .

  When the input voltage Vin is applied to the input terminal, when the main switching element Qm is turned on, current flows in the choke coil L1 to accumulate energy, and when the main switching element Qm is turned off thereafter, the energy is accumulated in the choke coil L1. The generated energy is superimposed on the input voltage Vin, flows through the rectifier diode D1, is smoothed by the capacitor C0, and is supplied to the load RL.

Japanese Patent Laid-Open No. 1996-205528 JP 2014-128027 A

  FIG. 11 shows a waveform diagram of each part when the above-described conventional non-insulated step-up switching power supply is analyzed by a circuit simulator PSIM developed by PowerSim.

  An N-channel MOSFET is used as the main switching element Qm. When a positive control voltage is applied to the gate voltage VGm, the drain-source becomes conductive, the drain current IDm flows, and the drain-source voltage decreases from the output voltage Vo to 0V. To do.

  The energy stored in the choke coil L1 during this period is released when the main switching element Qm is turned off, and is superposed on the input voltage Vin to be output to the capacitor C0.

  For example, the desired output voltage Vo can be obtained by adjusting the ON / OFF duty ratio of the main switching element Qm by PWM control.

  FIG. 12 shows an enlarged waveform when the main switching element Qm is turned on. When the gate voltage VGm is applied to the main switching element Qm and turned on, current flows in a region surrounded by a broken line in the figure, so that it can be seen that switching loss occurs.

  In FIG. 13, the waveform at the time of turn-off of the main switching element Qm is enlarged and displayed. When the gate voltage VGm applied to the main switching element Qm is lowered and turned off, a current flows in a region surrounded by a broken line in the figure, so that it can be seen that switching loss similarly occurs. And the loss which generate | occur | produces at the time of such switching becomes so large that a switching frequency is high.

  When such switching loss occurs, there is a problem that not only the boosting efficiency is lowered, but also the temperature of the circuit is increased, and therefore, the cost is increased due to an increase in heat radiation components.

  In view of the above-described problems, an object of the present invention is to provide a non-insulated step-up switching power supply device that can effectively reduce a loss generated during switching by adding a very simple circuit.

  In order to achieve the above-mentioned object, the first characteristic configuration of the non-isolated step-up switching power supply device according to the present invention is connected in series between the input and output terminals as described in claim 1 of the claims. A choke coil, a rectifier diode, a main switching element connected between a connection point of the choke coil and the rectifier diode, and a ground; and the main switching element connected to the anode side of the rectifier diode is interrupted. A non-isolated step-up switching power supply device configured to smooth a generated boost voltage, and a partial resonance circuit that supplies a reverse current to the main switching element when the main switching element is turned on. The main switching element is connected in parallel.

  According to the above configuration, a reverse current is supplied to the main switching element from the partial resonance circuit connected in parallel with the main switching element against the current flowing into the main switching element from the input terminal when the main switching element is turned on. As a result, both currents are substantially cancelled, and the switching loss becomes substantially zero.

  In the second characteristic configuration, as described in claim 2, in addition to the first characteristic configuration described above, the partial resonance circuit is connected in parallel with the main switching element, and the first resonant diode and the second resonant circuit are connected. A first series circuit including a capacitor and a second series circuit connected in parallel with the second capacitor and including a second resonant diode, a reactor, and a sub-switching element.

  A part of the current flowing toward the rectifier diode when the main switching element is turned off flows into the second capacitor via the first resonance diode, and is charged to substantially the same level as the output voltage. When the sub switching element is turned on in this state, the charge of the second capacitor is discharged through the second resonant diode, the reactor, and the sub switching element. When the charge of the second capacitor is discharged and the discharge current starts to decrease from the peak, a negative current flows through the main switching element for a predetermined time due to the counter electromotive force generated in the reactor. When the main switching element is turned on at this time, the current in the negative direction flows into the main switching element, so that no switching loss occurs at the time of turn-on. Further, the switching loss of the sub switching element is also reduced by the resonance operation. Furthermore, when the main switching element is turned off, the voltage across the second capacitor gradually increases because there is no charge in the second capacitor. As a result, the voltage rise of the main switching element becomes gradual and the switching loss is reduced, so that no switching loss occurs in the sub switching element.

  In addition to the second feature configuration described above, the third feature configuration includes a control circuit that turns on the sub switching element immediately before the main switching device is turned on. In the point.

  It is possible to reliably avoid the occurrence of switching loss when the main switching element is turned on.

  In the fourth feature configuration, as described in claim 4, in addition to the second or third feature configuration described above, the choke coil is configured by a primary side winding of a high-frequency transformer, and the reactor is configured by the reactor. It is in the point comprised by the secondary side winding of a high frequency transformer.

  By configuring the choke coil and the reactor with a high-frequency transformer, the space occupied by the components can be reduced and the size can be reduced.

  As described above, according to the present invention, it is possible to provide a non-insulated step-up switching power supply device that can effectively reduce loss generated during switching by adding a very simple circuit. It was.

Circuit diagram of switching power supply device according to the present invention The circuit diagram which connected the input power supply and the load element to the switching power supply device by this invention Explanatory drawing of the voltage applied to each part of the switching power supply device by this invention, and the flowing electric current Waveform diagram of each part showing simulation results for switching power supply device according to the present invention Waveform diagram of main part showing simulation results for switching power supply device according to present invention The enlarged waveform figure of the principal part which shows the simulation result at the time of turn-on of the main switching element in the switching power supply device by this invention The enlarged waveform figure of the principal part which shows the simulation result at the time of turn-off of the main switching element in the switching power supply device by this invention The enlarged waveform figure of the principal part which shows the simulation result at the time of the signal input of a subswitching element in the switching power supply device by this invention Comparison of characteristics of the circuit of the present invention and the conventional circuit Circuit diagram of conventional switching power supply Waveform diagram of the main part showing simulation results for a conventional switching power supply device Enlarged waveform diagram of the main part showing simulation results when the main switching element is turned on in a conventional switching power supply device Enlarged waveform diagram of the main part showing simulation results when the main switching element is turned off in a conventional switching power supply device

  Hereinafter, a non-insulated step-up switching power supply apparatus according to the present invention will be described with reference to the drawings. FIG. 1 shows a non-insulated step-up switching power supply device 100 according to the present invention.

  The non-insulated step-up switching power supply device 100 includes a choke coil L1 and a rectifier diode D1 connected in series between input and output terminals, and a main switching connected between a connection point between the choke coil L1 and the rectifier diode D1 and the ground. A non-insulated step-up switching power supply device comprising: an element Qm; and a capacitor Co that is connected to the anode side of the rectifier diode D1 and smoothes the boosted voltage generated when the main switching element Qm is intermittently connected. A partial resonance circuit that supplies a reverse current to the main switching element Qm when the main switching element Qm is turned on is connected in parallel with the main switching element Qm.

  A PWM signal for controlling the output voltage of the non-insulated step-up switching power supply device 100 is input from the feedback control circuit 10 to the gate of the switching element Qm. A control circuit 20 for generating a pulse signal immediately before the main switching element Qm is turned on is connected to the gate of the sub switching element Qs.

  The partial resonance circuit includes a first series circuit including a first resonance diode D2 and a second capacitor Cs connected in parallel to the main switching element Qm, and a second resonance diode D3 and a reactor L2 connected in parallel to the second capacitor Cs. And a second series circuit including the sub-switching element Qs.

  The choke coil L1 is composed of a primary side winding of the high frequency transformer T, and the reactor L2 is composed of a secondary side winding of the high frequency transformer T.

  FIG. 2 is a circuit in which the input power source Vin is connected to the input terminal of the non-insulated step-up switching power supply device 100 of the present invention shown in FIG. 1 and the load resistor RL is connected to the output terminal. The input power supply Vin is connected to the input terminal of the non-isolated step-up switching power supply apparatus 100 in FIG. 1, and the voltage boosted by operating the non-isolated step-up switching power supply apparatus 100 is supplied to the load RL connected to the output terminal. I can do it.

  FIG. 3 shows the voltage generated in each part and the flowing current when the isolated step-up switching power supply apparatus 100 of the present invention is operated.

  The symbol Vin indicates the voltage of the power supply connected to the input terminal. V1 is a voltage generated according to the current change amount of the choke coil L1. VGm represents the voltage of the PWL signal applied from the feedback control circuit 10 of FIG. 1 to the gate electrode of the main switching element Qm, and VGs represents a pulse applied from the timing control circuit 20 of FIG. 1 to the gate electrode of the sub switching element Qs. Indicates the voltage of the signal. VDSm represents a voltage generated between the source and drain of the main switching element Qm, and VDSs represents a voltage generated between the source and drain of the sub switching element Qs.

  IDm represents a current flowing between the drain and source of the main switching element Qm, and IDs represents a current flowing between the drain and source of the sub switching element Qs. IS indicates a current charged in the second capacitor, and VCS indicates a voltage generated between the terminals of the second capacitor Cs due to the current charged in the second capacitor. V2 indicates a voltage generated by the current flowing through the reactor L2. VD1 indicates a voltage generated between the anode terminal and the cathode terminal of the rectifier diode D1, and Vo indicates a voltage supplied from the output terminal to the load resistor RL.

  FIG. 4 shows a waveform diagram of each part when the isolated step-up switching power supply apparatus 100 of the present invention is analyzed by a circuit simulator PSIM developed by PowerSim.

  Hereinafter, the characteristics of the isolated step-up switching power supply device 100 according to the present invention will be described. FIG. 5 shows a waveform diagram of signals considered to be a main part in the non-insulated step-up switching power supply device of the present invention in the above-described simulation results.

  An N-channel MOSFET is used for the main switching element Qm, and a signal VGm generated by the feedback control circuit 10 is applied to its gate. An N-channel MOSFET is used as the sub switching element Qs, and a signal VGs generated by the timing control circuit 20 is applied to its gate.

  When a positive input voltage is applied to the gate of the main switching element Qm, the drain and the source become conductive, the drain current IDm flows, and the drain-source voltage VDSm decreases from the output voltage Vo to 0V. When a positive input voltage is applied to the gate of the sub-switching element Qs, the drain-source becomes conductive, the drain current IDs flows, and the drain-source voltage VDSs drops from the input voltage Vin to 0V. From FIG. 4, when a pulse signal is input to the gate of the sub switching element Qs to the positive voltage VGs and the drain and source of the sub switching element Qs are conducted, the voltage V2 applied to the reactor L2 is instantaneously 0V. As a result, the initial charge of the second capacitor Cs is discharged to 0 V at the moment when the drain and source of the sub switching element Qs are conducted. Further, since the voltage V2 applied to the reactor L2 includes the diode D3, even if the positive voltage VGs becomes 0 V at the gate of the sub switching element Qs and the drain and source of the sub switching element Qs become non-conductive, both ends thereof No voltage is applied. Therefore, the state of VDSs continues to be maintained as shown in FIG.

  The energy stored in the choke coil L1 during this period is released when the main switching element Qm is turned off, and is superimposed on the input voltage Vin to become the output voltage Vo, which is supplied to the smoothing capacitor Co. Same as power supply.

  First, with reference to FIG. 8, the simulation result when the gate voltage VGm of the main switching element Qm is turned on after the pulse signal VGs is applied to the gate of the sub switching element Qs is enlarged to explain the details of the circuit operation. To do.

  In the non-insulated partial resonance circuit of the present invention, energy is stored in the choke coil L1, and in parallel with the main switching element Qm against the current flowing from the input terminal to the main switching element Qm when the main switching element Qm is turned on. Since the sub-switching element Qs of the partial resonance circuit connected to is turned on before the main switching element Qm is turned on, a reverse current is supplied to the main switching element Qm through the reactor L2, so that both currents are substantially canceled out. Thus, the switching loss becomes almost zero.

  Next, with reference to FIG. 6, the waveform at the time of turn-on of the main switching element Qm is enlarged and the details of the circuit operation will be described. A part of the current that flows toward the rectifier diode D1 when the main switching element Qm is turned off flows into the second capacitor Cs via the first resonant diode D2, and is charged to substantially the same level as the output voltage. When the sub switching element Qs is turned on in this state, the charge of the second capacitor Cs is discharged through the second resonance diode D3, the reactor L2, and the sub switching element Qs.

  When the charge of the second capacitor Cs is discharged and the discharge current starts to decrease from the peak, a negative current flows through the main switching element Qm for a predetermined time due to the counter electromotive force generated in the reactor L2. At this time, when the main switching element Qm is turned on, the current in the negative direction flows into the main switching element Qm, so that no switching loss occurs at the time of turn-on. Further, the switching loss of the sub switching element Qs is also reduced by the resonance operation.

  In this way, it is possible to reliably avoid the occurrence of switching loss when the main switching element Qm is turned on.

  With reference to FIG. 7, the waveform of the main switching element Qm at the time of turn-off will be enlarged and the details of the main circuit operation will be described. When the main switching element Qm is turned off, the voltage across the second capacitor Cs gradually rises after that because the second capacitor Cs has no charge. As a result, the rise of the voltage of the main switching element Qm becomes gentle and the switching loss is reduced, so that no switching loss occurs in the sub switching element Qs.

  As described with reference to FIGS. 6 to 8, according to the non-insulated step-up switching power supply device of the present invention, it can be seen that the switching loss accompanying the switching operation is reduced or does not occur.

  Furthermore, by configuring the choke coil L1 and the reactor L2 with high frequency transformers, the space occupied by the components can be reduced and the size can be reduced.

  As described above, the characteristics of the conventional step-up chopper circuit and the non-insulated partial resonance circuit according to the present invention are compared with FIG. The power loss occurs during the switching operation of the switching element as described in the prior art in the conventional boost chopper circuit, whereas in the non-insulated partial resonance circuit of the present invention, the power loss is greatly reduced during the switching operation of the switching element. The In addition, since there are fewer high-frequency signals in circuit operation than in conventional circuits, high-frequency electromagnetic noise is less likely to occur.

  However, since it is necessary to generate the signal input to the gate of the sub switching element Qs, which was not found in the conventional circuit, in the timing control circuit 20 in synchronization with the signal input to the main switching element Qm, compared with the conventional circuit. The number of control parts is increasing.

  However, as described above, since electromagnetic noise is less likely to occur, the number of parts for countermeasures against electromagnetic noise required in the conventional circuit can be reduced in the circuit of the present invention.

Another embodiment of the present invention will be described below.
In the above-described embodiment, the circuit configuration of the boost power supply circuit has been described. However, by changing the configuration of the switching element, it can be applied to a step-down power supply circuit or other separately-excited switching power supply device that generates a voltage having a different polarity. It is.

  In the above-described embodiment, the high-frequency transformer T is used as the inductor. However, the choke coil L1 and the reactor L2 can be configured by individual inductors without using the high-frequency transformer T.

  The inductance of the resonance coil and the resonance capacitor capacity constituting the resonance circuit shown in the above-described embodiment are not particularly limited, and it is needless to say that appropriate values can be selected as long as the effects of the present invention are achieved. .

10: feedback control circuit 20: timing control circuit Qm: main switching element Qs: sub-switching element L1: choke coil L2: reactor Co: smoothing capacitor Cs: second capacitor D1: rectifier diode D2: first resonant diode D3: first 2 resonant diode

Claims (4)

A choke coil and a rectifier diode connected in series between the input and output terminals, a main switching element connected between a connection point between the choke coil and the rectifier diode and the ground, and connected to the anode side of the rectifier diode A capacitor for smoothing a boosted voltage generated when the main switching element is interrupted, and a non-insulated boosting switching power supply device,
A non-insulated step-up switching power supply apparatus in which a partial resonance circuit that supplies a reverse current to the main switching element when the main switching element is turned on is connected in parallel with the main switching element.   The partial resonance circuit includes a first series circuit including a first resonance diode and a second capacitor connected in parallel to the main switching element, and a second resonance diode, a reactor, and sub-switching connected in parallel to the second capacitor. The non-insulated step-up switching power supply device according to claim 1, comprising a second series circuit including an element.   3. The non-insulated step-up switching power supply device according to claim 2, further comprising a control circuit that turns on the sub switching element immediately before the main switching element is turned on. 4. The non-insulated step-up switching power supply apparatus according to claim 2, wherein the choke coil is constituted by a primary side winding of a high frequency transformer, and the reactor is constituted by a secondary side winding of the high frequency transformer.

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