Output stabilization circuit and DCDC converter circuit

Abstract

To provide a circuit technique capable of stabilizing an output voltage with a simple circuit structure.SOLUTION: An output stabilizing circuit (1) comprises a primary side circuit (2) and a secondary side circuit (3), containing first and second self-excited oscillation circuits (10 and 20) connected to a DC power supply (BT). Each of the first and second self-excited oscillation circuits contains; power transmission coils (N11, N12, N21, and N22); resonance capacitors (C11 and C21); switching element pairs (Q11, Q12, Q21, and Q22); and feedback coils (Nf1 and Nf2), The second self-excited oscillation circuit (20) further contains a phase shift filter (F20). The phase shift filter (F20) contains a primary side control coil (Lf21) that is magnetically bonded with a secondary side control coil (Lc31) contained in the secondary side circuit (3), and has a characteristic, which is that an inductance is changed in accordance with a current flowing in the secondary side control coil.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a self-oscillating circuit and a DC-DC converter circuit. [Background technology]

[0002] Unlike separately excited circuits, there are inverter circuits and power supply circuits that simplify the circuitry by adopting self-oscillating circuits that do not use control ICs, etc. The following Patent Document 1 discloses a self-excited resonant power supply that controls the output voltage by shifting the self-oscillation frequency by supplying an error signal corresponding to the deviation between a voltage signal corresponding to the output voltage and a reference signal to each gate of a first and second transistor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-285262 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are concerns that the above-mentioned circuit has a narrow range of applicability, such as the possibility that the FET (field effect transistor) may enter unsaturated operation when the gate bias of the FET is increased or decreased, that waveform abnormalities may occur due to deviation from the conditions for self-oscillation, and that FET loss increases due to an increase in reactive current in the parallel resonant section. The present invention provides a circuit technique for stabilizing an output voltage with a simple circuit configuration, regardless of the conditions relating to self-oscillation. [Means for solving the problem]

[0005] According to the present invention, there is provided an output stabilization circuit including a primary side circuit including a first self-excited oscillating circuit and a second self-excited oscillating circuit connected to a DC power supply, and a secondary side circuit that obtains an output voltage by oscillation of the first self-excited oscillating circuit and the second self-excited oscillating circuit, wherein the first self-excited oscillating circuit includes a first power transmitting coil, a first resonant capacitor that forms a resonant circuit together with the first power transmitting coil, a first switching element pair connected to the first power transmitting coil, and a first feedback coil that is magnetically coupled to the first power transmitting coil and connected to each control electrode of the first switching element pair, and the second self-excited oscillating circuit includes a second power transmitting coil, a first resonant capacitor that forms a resonant circuit together with the second power transmitting coil, An output stabilization circuit is provided, comprising: a resonant capacitor; a second switching element pair connected to the second power transmission coil; a second feedback coil magnetically coupled to the first feedback coil and connected to each control electrode of the second switching element pair; and a phase shift filter connected between the second feedback coil and each control electrode of the second switching element pair, wherein the secondary side circuit includes a secondary side control coil whose magnitude of current flowing therethrough is controlled in accordance with the magnitude of the output voltage, and the phase shift filter includes a primary side control coil magnetically coupled to the secondary side control coil and having a characteristic that inductance changes in accordance with the current flowing through the secondary side control coil. Effect of the Invention

[0006] According to the above aspect, it is possible to provide a circuit technique for stabilizing an output voltage with a simple circuit configuration without being concerned with conditions relating to self-oscillation. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a circuit diagram of a power supply circuit according to the first embodiment. [Diagram 2] FIG. 11 is a circuit diagram of a secondary side circuit in a modified example of the first embodiment. [Diagram 3] FIG. 11 is a circuit diagram of a power supply circuit according to a second embodiment. [Figure 4] 2 is a circuit diagram of a secondary side circuit of the power supply circuit in the first embodiment. FIG. [Diagram 5]4 is a graph showing the results of simulating voltage changes at each point in the power supply circuit of the first embodiment. [Figure 6] 4 is a graph showing the results of simulating voltage changes at each point in the power supply circuit of the first embodiment. [Figure 7] 4 is a graph showing the results of simulating voltage changes at each point in the power supply circuit of the first embodiment. [Figure 8] FIG. 11 is a circuit diagram of a secondary side circuit of a power supply circuit in a second embodiment. [Figure 9] 13 is a graph showing the results of simulating voltage changes at each point in the power supply circuit of Example 2. [Figure 10] FIG. 11 is a circuit diagram of a secondary side circuit of a power supply circuit according to a third embodiment. [Figure 11] 13 is a graph showing the results of simulating voltage changes at each point in the power supply circuit of the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, preferred embodiments of the present invention (hereinafter, referred to as the present embodiments) will be described. Note that the following embodiments are merely examples, and the present invention is not limited to the configurations of the following embodiments.

[0009] [First embodiment] FIG. 1 is a circuit diagram of a power supply circuit 1 in the first embodiment. The power supply circuit 1 includes a primary side circuit 2 having a battery device BT and a secondary side circuit 3 that obtains an output voltage from the primary side circuit 2, and is a circuit that provides a stable output to a load connected to the secondary side circuit 3. In the first embodiment, the battery device BT is a battery device that supplies DC power, the secondary side circuit 3 includes a DC conversion circuit S30, and an example is shown in which the power supply circuit 1 functions as a DC-DC converter circuit as a whole.

[0010] [Primary side circuit] The primary side circuit 2 further includes a master circuit 10 and a slave circuit 20 connected in parallel to the battery device BT. The master circuit 10 includes power transmitting coils N11 and N12, a resonant capacitor C11, transistors Q11 and Q12 as a switching element pair, a bias circuit B10, a feedback coil Nf1, and the like, which together form a self-oscillating circuit.

[0011] The transmitting coil N11 and the transmitting coil N12 are connected in series via a center tap, and the center tap is connected to the positive terminal of the battery device BT via the input coil L11. Hereinafter, when one end of the transmitting coil N11 or one end of the transmitting coil N12 is written, it means one end of the transmitting coils N11 and N12 opposite to the center tap side. One end of the power transmitting coil N11 is connected to the negative terminal of the battery device BT via a transistor Q11, and one end of the power transmitting coil N12 is connected to the negative terminal of the battery device BT via a transistor Q12.

[0012] The resonant capacitor C11 is connected in parallel to the power transmitting coils N11 and N12, and forms a resonant circuit together with the power transmitting coils N11 and N12. The transistors Q11 and Q12 are FETs (Field Effect Transistors) and can be described as a switching element pair. The drain of the transistor Q11 is connected to one end of the power transmitting coil N11, and the drain of the transistor Q12 is connected to one end of the power transmitting coil N12. The sources of the transistors Q11 and Q12 are connected to the negative terminal of the battery device BT. The gates of the transistors Q11 and Q12 are connected to the bias circuit B10.

[0013] The bias circuit B10 is composed of resistor elements R11, R12, R13, and R14. The bias circuit B10 is connected in parallel to the battery device BT, and applies a bias voltage to the gates of the transistors Q11 and Q12. The feedback coil Nf1 is provided so as to be magnetically coupled to the power transmitting coils N11 and N12. One end of the feedback coil Nf1 is connected to the gate (control electrode) of the transistor Q11, and the other end of the feedback coil Nf1 is connected to the gate (control electrode) of the transistor Q12.

[0014] Except for the phase-shift filter F20, the slave circuit 20 includes the same configuration as the master circuit 10. Specifically, the slave circuit 20 includes power transmitting coils N21 and N22, a resonant capacitor C21, transistors Q21 and Q22 as a switching element pair, a bias circuit B20, a feedback coil Nf2, and the like, which together form a self-oscillating circuit. The transmitting coils N21 and N22 correspond to the above-mentioned transmitting coils N11 and N12, the resonant capacitor C21 corresponds to the above-mentioned resonant capacitor C11, the transistors Q21 and Q22 correspond to the above-mentioned transistors Q11 and Q12, the bias circuit B20 (resistance elements R21, R22, R23, and R24) corresponds to the above-mentioned bias circuit B10 (resistance elements R11, R12, R13, and R14), and the feedback coil Nf2 corresponds to the above-mentioned feedback coil Nf1. Regarding each of these components of the slave circuit 20, the description of the same contents (connection configuration, etc.) as the corresponding components of the master circuit 10 will be omitted as appropriate.

[0015] The feedback coil Nf2 of the slave circuit 20 is provided so as to be magnetically coupled to the power transmitting coils N11 and N12 and the feedback coil Nf1 in the master circuit 10. More specifically, the feedback coil Nf2 is magnetically coupled to the feedback coil Nf1 so as to have the same polarity. The feedback coil Nf2 is not magnetically coupled to the power transmitting coils N21 and N22 of the slave circuit 20. In this embodiment, the transmitting coil N11, the transmitting coil N12, and the feedback coil Nf1 in the master circuit 10, and the feedback coil Nf2 in the slave circuit 20, together with the receiving coil N31 in the secondary side circuit 3, form a transformer (first transformer), and the transmitting coils N21 and N22 in the slave circuit 20, together with the receiving coil N32 in the secondary side circuit 3, form a transformer (second transformer). As described above, in this embodiment, the primary side circuit 2 and the secondary side circuit 3 are electrically insulated from each other, and are configured to be able to transmit power from the primary side circuit 2 to the secondary side circuit 3 by electromagnetic induction of the first transformer and the second transformer.

[0016] The phase-shift filter F20 is connected between the gates (control electrodes) of the transistors Q21 and Q22 and the feedback coil Nf2. The phase-shift filter F20 is composed of a resistive element Rf21, a primary-side control coil Lf21, and a capacitor Cf21, and can also be expressed as an RLC filter. The resistive element Rf21 and the primary-side control coil Lf21 are connected in series to the feedback coil Nf2, and the capacitor Cf21 is connected in parallel to the feedback coil Nf2. This allows the phase-shift filter F20 to form a low-pass filter. With this configuration, the phase-shift filter F20 acts to delay the phase of the AC voltage generated in the feedback coil Nf2 in association with the magnetic field generated in the first transformer by the current in the power transmission coil N11 or N12.

[0017] Furthermore, the primary side control coil Lf21 of the phase shift filter F20 is magnetically coupled to a secondary side control coil Lc31 (described later) of the secondary side circuit 3, and has a characteristic that its inductance changes according to the current flowing through the secondary side control coil Lc31. Since the inductance of the primary side control coil Lf21 is variable in this manner, the magnitude of the phase shift by the phase shift filter F20 is variable.

[0018] In addition to the above-mentioned configuration, the primary side circuit 2 includes a fuse FU and a capacitor C. The fuse FU separates the battery BT from the primary circuit 2 when an excessive current occurs due to an abnormality in the self-excited oscillation circuit (the master circuit 10 and the slave circuit 20) of the primary circuit 2. This makes it possible to prevent the battery BT from being abnormally heated due to the excessive current. The capacitor C absorbs the change in voltage caused by the charging and discharging of the battery device BT.

[0019] [Secondary side circuit] The secondary circuit 3 includes receiving coils N31 and N32, a rectifier circuit SR30, a reference voltage circuit RV30, and the like. As described above, the receiving coil N31 constitutes a transformer as a secondary coil with the transmitting coil N11 and the transmitting coil N12 in the power supply circuit 1 as primary coils, and generates an induced electromotive force due to the current in the transmitting coil N11 or N12. As described above, the receiving coil N32 constitutes a transformer as a secondary coil with the transmitting coil N21 and the transmitting coil N22 in the power supply circuit 1 as primary coils, and generates an induced electromotive force due to the current in the transmitting coil N21 or N22. The receiving coils N31 and N32 are connected in series so that the coil voltages are in opposite phases, so that in theory, when the voltage induced in the receiving coils N31 and N32 is synchronized, the output is zero.

[0020] The rectifier circuit SR30 is connected to the receiving coils N31 and N32. The rectifier circuit SR30 has a bridge rectifier circuit formed by diodes D31, D32, D33, and D34, and a smoothing filter formed by a coil L31 and a capacitor C31, and functions as a full-wave rectifier circuit. In other words, the rectifier circuit SR30 full-wave rectifies and smoothes the AC voltage generated in the receiving coils N31 and N32 to convert it into a DC voltage.

[0021] The reference voltage circuit RV30 includes resistor elements R31 and R32 and a shunt regulator element Ic31, and is a circuit that stabilizes the output voltage from the secondary side circuit 3 to a reference voltage or higher. The shunt regulator element Ic31 receives at its reference terminal the voltage obtained by dividing the output voltage by resistor elements R31 and R32, and controls the voltage between the reference and anode to be the reference voltage. The reference voltage circuit RV30 further includes a secondary side control coil Lc31. A current flows through the secondary control coil Lc31 according to the voltage control of the shunt regulator element Ic31. That is, when the output voltage becomes higher than the reference voltage, the current flowing through the secondary control coil Lc31 increases, and when the output voltage becomes lower than the reference voltage, the current flowing through the secondary control coil Lc31 decreases.

[0022] As described above, the secondary control coil Lc31 is magnetically coupled to the primary control coil Lf21, and the inductance of the primary control coil Lf21 is made variable depending on the amount of current flowing through the secondary control coil Lc31. The primary control coil Lf21 and the secondary control coil Lc31 form a transformer with one magnetic path, with the primary winding and the secondary winding wound around a common core. This transformer is configured to have an inductance DC superposition characteristic such that the greater the DC current flowing through the secondary control coil Lc31, the greater the inductance reduction rate of the primary control coil Lf21. As a result, in the phase shift filter F20, due to the RLC filter characteristic, the greater the inductance value of the primary control coil Lf21, the greater the amount of phase shift (the greater the phase difference between the output signal of the feedback coil Nf2 and the signals input to the gates of the transistors Q21 and Q22). With this configuration, the amount of phase shift of the phase-shift filter F20 can be increased or decreased according to the output voltage from the secondary side circuit 3, and thus the output voltage from the secondary side circuit 3 can be stabilized.

[0023] Hereinafter, the operation of the power supply circuit 1 in the first embodiment having the above-mentioned configuration will be described. In the master circuit 10, when DC power is supplied from the battery device BT to the bias circuit B10, a voltage divided by the resistor elements R11 and R12 is applied as a bias voltage to the gate of the transistor Q11, and a voltage divided by the resistor elements R13 and R14 is applied as a bias voltage to the gate of the transistor Q12. As a result, depending on the transistor characteristics and the resistance values ​​of the resistor elements R11 and R13, either the transistor Q11 or Q12 is turned on first.

[0024] At this time, when the transistor Q11 is turned on, a current flows through the power transmitting coil N11, and a current flows between the drain and source of the transistor Q11. When a current flows through the power transmitting coil N11, which is the primary winding, a magnetic field is generated in the first transformer, and an induced electromotive force is generated in the power receiving coil N31, which is the secondary winding. The induced electromotive force generated in the power receiving coil N31 can be amplified according to the turns ratio between the power transmitting coil N11 and the power receiving coil N31. When a magnetic field is generated in the first transformer, a back electromotive force is also generated in the feedback coils Nf1 and Nf2, which are the primary windings, due to self-induction.

[0025] When a back electromotive force is generated in the feedback coil Nf1, a negative voltage is applied to the transistor Q11, the bias voltage applied to the transistor Q11 becomes equal to or lower than the threshold voltage, and the transistor Q11 is turned off. On the other hand, a positive voltage is applied to the transistor Q12, the bias voltage applied to the transistor Q12 becomes higher than the threshold voltage, and the transistor Q12 is turned on.

[0026] When the transistor Q11 is turned off and the transistor Q12 is turned on, a current flows through the power transmitting coil N12 and between the drain and source of the transistor Q12. When a current flows through the power transmission coil N12, which is the primary winding, a magnetic field is generated in the first transformer, and an induced electromotive force is generated in the power receiving coil N31, which is the secondary winding. In this manner, in the master circuit 10, the on and off states of the transistors Q11 and Q12 are alternately repeated, so that currents flow alternately in opposite directions through the power transmitting coils N11 and N12, which are the primary windings.

[0027] On the other hand, the slave circuit 20 operates in a similar manner. That is, when DC power is supplied from the battery device BT to the bias circuit B20, a voltage divided by the resistor elements R21 and R22 is applied as a bias voltage to the gate of the transistor Q21, and a voltage divided by the resistor elements R23 and R24 is applied as a bias voltage to the gate of the transistor Q22. As a result, depending on the transistor characteristics and the resistance values ​​of the resistor elements R21 and R23, either the transistor Q21 or Q22 is turned on first.

[0028] At this time, when the transistor Q21 is turned on, a current flows through the power transmitting coil N21, and a current flows between the drain and source of the transistor Q21. When a current flows through the power transmitting coil N21, which is the primary winding, a magnetic field is generated in the second transformer, and an induced electromotive force is generated in the power receiving coil N32, which is the secondary winding. The induced electromotive force generated in the power receiving coil N32 can be amplified according to the winding ratio between the power transmitting coil N21 and the power receiving coil N32.

[0029] At this time, as described above, the same operation occurs in the master circuit 10, and a back electromotive force is generated in the feedback coil Nf2, which is the primary winding, due to self-induction caused by the magnetic field generated in the first transformer of the master circuit 10. Here, the voltage generated in the feedback coil Nf2 is shifted in phase by the phase-shift filter F20 and applied to the transistors Q21 and Q22. At this time, a negative voltage is applied to the transistor Q21, and the bias voltage applied to the transistor Q21 becomes equal to or lower than the threshold voltage, and the transistor Q21 is turned off. On the other hand, a positive voltage is applied to the transistor Q22, and the bias voltage applied to the transistor Q22 exceeds the threshold voltage, and the transistor Q22 is turned on.

[0030] When the transistor Q21 is turned off and the transistor Q22 is turned on, a current flows through the power transmitting coil N22 and between the drain and source of the transistor Q22. When a current flows through the primary winding, the transmitting coil N22, a magnetic field is generated in the second transformer, and an induced electromotive force is generated in the secondary winding, the receiving coil N32. In this manner, in the slave circuit 20, the on and off states of the transistors Q21 and Q22 are alternately repeated, so that currents flow alternately in opposite directions through the power transmitting coils N21 and N22, which are the primary windings. However, in the slave circuit 20, the phase of the voltage generated in the feedback coil Nf2 is shifted by the action of the phase-shift filter F20, causing the on / off timing of the transistors Q21 and Q22 to differ from the on / off timing of the transistors Q11 and Q12 in the master circuit 10. As a result, the switching timing of the current in the transmitting coils N21 and N22 differs from the switching timing of the current in the transmitting coils N11 and N12.

[0031] Due to this operation of the primary circuit 2, a magnetic field is generated in the first transformer and the second transformer, and an AC voltage consisting of alternating positive and negative voltages is induced in the receiving coils N31 and N32, which are the secondary windings in the secondary circuit 3. However, as described above, the timing of the current switching in the transmitting coils N21 and N22 is shifted from the timing of the current switching in the transmitting coils N11 and N12, so that the phase of the AC voltage induced in the receiving coil N31 and the AC voltage induced in the receiving coil N32 also shifts.

[0032] In the secondary side circuit 3, the AC voltage generated in the power receiving coil N31 and the AC voltage generated in the power receiving coil N32 are combined and input to the rectifier circuit SR30, where they are converted into a DC voltage by full-wave rectification and smoothing. When the converted DC voltage is input to a reference voltage circuit RV30, the output voltage is controlled by a shunt regulator element Ic31 so as to be equal to or higher than the reference voltage, and then output. At this time, a current amount according to the output voltage flows through the secondary side control coil Lc31. The inductance value of the primary side control coil Lf21, which is magnetically coupled to the secondary side control coil Lc31, changes according to this current amount. The change in the inductance value of the primary side control coil Lf21 changes the amount of phase shift of the phase shift filter F20.

[0033] In this embodiment, the receiving coil N31 and the receiving coil N32 are connected so that the coil voltages are in opposite phase, so that the more synchronized (the more in phase) the AC voltage generated in the receiving coil N31 and the AC voltage generated in the receiving coil N32 are, the lower the output voltage will be, and the closer the phase shift is to 90 degrees, the higher the output voltage will be. Therefore, due to the action of the primary side control coil Lf21, resistive element Rf21, and capacitor Cf21 described above, the phase-shift filter F20 performs a phase shift in the direction in which the AC voltages generated in the receiving coils N31 and N32 are synchronized when the amount of current flowing through the secondary side control coil Lc31 is large, and performs a phase shift in the direction in which the phases of the AC voltages generated in the receiving coils N31 and N32 are shifted when the amount of current is small.

[0034] Therefore, according to this embodiment, while the output voltage fluctuates according to the fluctuation of the input DC voltage in the existing collector resonant self-oscillating circuit, this phase shift operation makes it possible to stabilize the output voltage with a simple circuit configuration. Therefore, the power supply circuit 1 in this embodiment can be described as an output stabilization circuit.

[0035] [Modification of the first embodiment] In the first embodiment described above, the power supply circuit 1 is exemplified as a DC-DC converter circuit that outputs a DC voltage. However, by modifying the secondary side circuit 3, a circuit configuration that outputs a sine wave voltage can also be used. 2 is a circuit diagram of a secondary side circuit 3 in a modified example of the first embodiment. In this modified example, the primary side circuit 2 may have the same configuration as that in the first embodiment shown in FIG. In this modification, the bridge rectifier circuit configured by diodes D31, D32, D33, and D34 is removed from the secondary side circuit 3. Also, the reference voltage circuit RV31 further includes a diode D35 and a capacitor C32 in addition to the configuration of the reference voltage circuit RV30 in the first embodiment.

[0036] In the secondary side circuit 3 of this modified example, the AC voltage (sine wave voltage) generated in the receiving coil N31 and the AC voltage (sine wave voltage) generated in the receiving coil N32 are combined, and after high-frequency noise components are removed by a low-pass filter (L31 and C31), the resultant voltage is input to the reference voltage circuit RV31. In the reference voltage circuit RV31, the AC is rectified and smoothed to DC by the diode D35 and the capacitor C32, and thereafter, the function is the same as that of the reference voltage circuit RV31 in the first embodiment, making it possible to stabilize the output.

[0037] Therefore, according to this modification, a "stabilized sine wave output" can be obtained by taking the output after the low-pass filter (L31 and C31).

[0038] [Second embodiment] FIG. 3 is a circuit diagram of the power supply circuit 1 in the second embodiment. The power supply circuit 1 in the second embodiment differs from the first embodiment in that the power receiving coil N31 and the power receiving coil N32 in the secondary side circuit 3 are connected so that the coil voltages are in phase, and in the configuration of the phase shift filter F20. The following description of the power supply circuit 1 in the second embodiment will focus on the differences from the first embodiment, and the same contents as in the first embodiment will be omitted as appropriate.

[0039] In the second embodiment, the receiving coil N31 and the receiving coil N32 are connected so that the coil voltages are in phase, so that the more synchronized (the more in phase) the AC voltage generated in the receiving coil N31 and the AC voltage generated in the receiving coil N32 are, the higher the output voltage will be, and the closer the phase shift is to 90 degrees, the lower the output voltage will be. Therefore, when the amount of current flowing through the secondary control coil Lc31 is large, the phase-shift filter F20 must perform a phase shift in a direction that shifts the phase of the AC voltage generated in the receiving coils N31 and N32, and when the amount of current flowing through the secondary control coil Lc31 is small, the phase-shift filter F20 must perform a phase shift in a direction that synchronizes the AC voltages generated in the receiving coils N31 and N32. Therefore, in the phase-shift filter F20 of the second embodiment, the second feedback coil Nf22 and the capacitor Cf21 are connected in series, and the primary-side control coil Lf21 is connected in parallel to the second feedback coil Nf2 and the capacitor Cf21. That is, the phase-shift filter F20 constitutes a high-pass filter, thereby enabling the above-mentioned phase shift.

[0040] Therefore, according to the second embodiment, even if the receiving coil N31 and the receiving coil N32 in the secondary side circuit 3 are connected so that the coil voltages are in phase, it is possible to achieve stabilization of the output voltage with a simple circuit configuration, as in the first embodiment.

[0041] [Modification of the second embodiment] When the power receiving coil N31 and the power receiving coil N32 are connected in the secondary side circuit 3 so that the coil voltages are in phase, the configuration of the phase shift filter F20 can be the same as that of the first embodiment. In this case, the feedback coil Nf1 and the feedback coil Nf2 can be configured to be magnetically coupled with opposite polarities. In this way, the voltage induced in the feedback coil Nf1 and the voltage induced in the feedback coil Nf2 can be made to be of opposite phase, so that the same effect as in the first embodiment can be obtained even when the receiving coil N31 and the receiving coil N32 in the secondary side circuit 3 are connected so that the coil voltages are in phase.

[0042] The above content will be described in more detail below with reference to examples, but the description of the following examples does not limit the above content in any way. EXAMPLES

[0043] In Example 1, the results of verifying the effects of the above-mentioned first embodiment by simulation are shown. FIG. 4 is a circuit diagram of the secondary side circuit 3 of the power supply circuit 1 in the first embodiment. In the simulation of Example 1, the inductance of the primary side control coil Lf21 was not controlled by magnetic coupling between the primary side control coil Lf21 and the secondary side control coil Lc31, and the inductance value of the primary side control coil Lf21 was set virtually and manually. Therefore, the reference voltage circuit RV30 is not provided in the secondary side circuit 3, and a load resistor R0 is connected thereto. The primary side circuit 2 has the same configuration as that of the first embodiment shown in FIG.

[0044] 5 to 7 are graphs showing the results of simulating voltage changes at each point in the power supply circuit 1 of Example 1. In Fig. 5 to 7, (a) shows the simulation results when the inductance value of the primary side control coil Lf21 is set to a first value, and (b) shows the simulation results when the inductance value of the primary side control coil Lf21 is set to a second value larger than the first value.

[0045] Figures 5(a) and 5(b) show the voltage waveform (output waveform) induced in the feedback coil Nf2, the voltage waveform induced in the feedback coil Nf2 after the phase-shift filter F20 is applied (after passing through), and the voltage waveform input to the gate of transistor Q22. According to FIG. 5(a), when the inductance value of the primary side control coil Lf21 is set to a first value (small), the phase of the voltage generated in the feedback coil Nf2 is significantly shifted by the phase-shift filter F20 and applied to the gate of the transistor Q22. On the other hand, according to FIG. 5(b), when the inductance value of the primary side control coil Lf21 is set to the second value (large), the amount of phase shift by the phase shift filter F20 is smaller than in the case of FIG. 4(a), and it can be seen that the phase of the voltage generated in the feedback coil Nf2 is slightly shifted by the phase shift filter F20 and applied to the gate of the transistor Q22.

[0046] 6(a) and 6(b) show the drain-source voltage waveform (output waveform) of transistor Q12 in the master circuit 10 and the drain-source voltage waveform (output waveform) of transistor Q22 in the slave circuit 20. 6(a) shows that when the inductance value of the primary side control coil Lf21 is set to a first value (small), there is a large phase shift between the voltage waveform of the transistor Q12 in the master circuit 10 and the voltage waveform of the transistor Q22 in the slave circuit 20. This shows that by increasing the phase shift amount of the voltage waveform generated in the feedback coil Nf2, it is possible to greatly shift the switching timing of the transistors Q11 and Q12 in the master circuit 10 from the switching timing of the transistors Q21 and Q22 in the slave circuit 20. 6(b), when the inductance value of the primary side control coil Lf21 is set to the second value (large), there is a small phase shift between the voltage waveform of the transistor Q12 in the master circuit 10 and the voltage waveform of the transistor Q22 in the slave circuit 20. This shows that by reducing the phase shift of the voltage waveform generated in the feedback coil Nf2, it is possible to reduce the shift between the switching timing of the transistors Q11 and Q12 in the master circuit 10 and the switching timing of the transistors Q21 and Q22 in the slave circuit 20.

[0047] 7(a) and 7(b) show the DC voltage level applied to the load resistor and the full-wave rectified waveform on the cathode side of diode D33. According to Figure 7(a), when the inductance value of the primary side control coil Lf21 is set to a first value (small), there is a large phase shift between the voltage waveform generated in the receiving coil N31 and the voltage waveform generated in the receiving coil N32, and the DC voltage level after full-wave rectification of the combined voltage waveform becomes relatively large. On the other hand, according to Figure 7(b), when the inductance value of the primary side control coil Lf21 is set to the second value (large), the phase difference between the voltage waveform generated in the receiving coil N31 and the voltage waveform generated in the receiving coil N32 is small, and therefore the DC voltage level after full-wave rectification of the combined voltage waveform is smaller than in the case of Figure 7(a).

[0048] Thus, according to Example 1, it has been demonstrated that in the power supply circuit 1 of the first embodiment, the output voltage can be controlled by changing the amount of phase shift by the phase shift filter F20 depending on the magnitude of the inductance value of the primary side control coil Lf21, and thus stabilization of the output voltage can be achieved. EXAMPLES

[0049] In Example 2, the effect of the modification of the above-mentioned first embodiment is verified by simulation. FIG. 8 is a circuit diagram of the secondary side circuit 3 of the power supply circuit 1 in the second embodiment. In the simulation of the second embodiment, similarly to the first embodiment, the inductance value of the primary side control coil Lf21 was virtually set manually. Therefore, the reference voltage circuit RV30 is not provided in the secondary side circuit 3, and a load resistor R0 is connected thereto. The primary side circuit 2 has the same configuration as that of the first embodiment shown in FIG.

[0050] Fig. 9 is a graph showing the results of simulating voltage changes at each point in the power supply circuit 1 of Example 2. Fig. 9(a) shows the simulation results when the inductance value of the primary side control coil Lf21 is set to a first value, and Fig. 9(b) shows the simulation results when the inductance value of the primary side control coil Lf21 is set to a second value larger than the first value. The voltage waveforms at each point in the primary side circuit 2 in Example 2 are similar to those in Example 1 (Figs. 5 and 6).

[0051] 9(a) and 9(b) show a voltage waveform (output waveform) induced in the receiving coil N31, a voltage waveform (output waveform) induced in the receiving coil N32, and a voltage waveform of a load resistor. According to Figure 9(a), when the inductance value of the primary side control coil Lf21 is set to a first value (small), the phase of the voltage waveform generated in the receiving coil N31 and the voltage waveform generated in the receiving coil N32 are significantly shifted, and the combined voltage waveform becomes relatively large. On the other hand, according to Figure 9(b), when the inductance value of the primary side control coil Lf21 is set to the second value (large), the phase difference between the voltage waveform generated in the receiving coil N31 and the voltage waveform generated in the receiving coil N32 is small, and therefore the composite voltage waveform is smaller than in the case of Figure 9(a).

[0052] Thus, according to Example 2, it has been demonstrated that, even in the case where a configuration is adopted in which the secondary side circuit 3 outputs a sinusoidal voltage, in the power supply circuit 1 of the first embodiment, stabilization of the output voltage can be achieved by the phase shift operation of the phase shift filter F20. EXAMPLES

[0053] In Example 3, the results of verifying the effects of the above-mentioned second embodiment by simulation will be shown. FIG. 10 is a circuit diagram of the secondary side circuit 3 of the power supply circuit 1 in the third embodiment. In Example 3, unlike Examples 1 and 2, the receiving coils N31 and N32 are connected so that the coil voltages are in phase. In the simulation of Example 3, as in Example 1, the inductance value of the primary control coil Lf21 was virtually set manually. Therefore, the secondary circuit 3 is not provided with a reference voltage circuit RV30, and a load resistor R0 is connected. The primary circuit 2 has the same configuration as that of the second embodiment shown in FIG. 3.

[0054] Fig. 11 is a graph showing the results of simulating voltage changes at each point in the power supply circuit 1 of Example 3. Fig. 11(a) shows the simulation results when the inductance value of the primary side control coil Lf21 is set to a first value (small), and Fig. 11(b) shows the simulation results when the inductance value of the primary side control coil Lf21 is set to a second value (large) that is larger than the first value.

[0055] Figures 11(a) and 11(b) show the drain-source voltage waveform (output waveform) of transistor Q12 in the master circuit 10, the drain-source voltage waveform (output waveform) of transistor Q22 in the slave circuit 20, and the DC voltage level applied to the load resistor. According to FIG. 11(a), when the inductance value of the primary side control coil Lf21 is set to a first value (small), the phase of the voltage waveform of the transistor Q12 of the master circuit 10 and the voltage waveform of the transistor Q22 of the slave circuit 20 are significantly shifted, and the DC voltage level after full-wave rectification of the combined voltage waveform is small (2.4 V). On the other hand, according to FIG. 11(b), when the inductance value of the primary side control coil Lf21 is set to the second value (large), the phase shift between the voltage waveform of the transistor Q12 in the master circuit 10 and the voltage waveform of the transistor Q22 in the slave circuit 20 is small, and the DC voltage level after full-wave rectification of the combined voltage waveform is larger (12.7 V) than in the case of FIG. 11(a).

[0056] Thus, according to Example 3, even in the power supply circuit 1 of the second embodiment in which the receiving coil N31 and the receiving coil N32 in the secondary side circuit 3 are connected so that the coil voltages are in phase, it has been demonstrated that the output voltage can be controlled by changing the amount of phase shift by the phase shift filter F20 depending on the magnitude of the inductance value of the primary side control coil Lf21, and thus stabilization of the output voltage can be achieved.

[0057] Some or all of the above-described embodiments and modifications may be specified as follows. However, the above-described embodiments and modifications are not limited to the following descriptions.

[0058] (1) An output stabilization circuit including a primary side circuit including a first self-oscillating circuit and a second self-oscillating circuit connected to a DC power source, and a secondary side circuit that obtains an output voltage by oscillation of the first self-oscillating circuit and the second self-oscillating circuit, The first self-oscillating circuit includes: A first transmitting coil; and a first resonant capacitor that configures a resonant circuit together with the first power transmitting coil; and a first switching element pair connected to the first power transmitting coil; a first feedback coil that is magnetically coupled to the first power transmission coil and connected to each control electrode of the first switching element pair; having The second self-oscillating circuit includes: A second power transmitting coil; and a second resonant capacitor that configures a resonant circuit together with the second power transmitting coil; and a second switching element pair connected to the second power transmitting coil; a second feedback coil magnetically coupled to the first feedback coil and connected to each control electrode of the second switching element pair; a phase-shift filter connected between the second feedback coil and each control electrode of the second switching element pair; having the secondary side circuit includes a secondary side control coil in which a magnitude of a current flowing therethrough is controlled in accordance with a magnitude of the output voltage; the phase shift filter includes a primary control coil that is magnetically coupled to the secondary control coil and has an inductance that changes in response to a current flowing through the secondary control coil; Output stabilization circuit. (2) The secondary side circuit includes: a first power receiving coil that constitutes a transformer together with the first power transmitting coil; a second power receiving coil that constitutes a transformer together with the second power transmitting coil; and The first receiving coil and the second receiving coil are connected so that the coil voltages are in opposite phases, The first feedback coil and the second feedback coil are magnetically coupled to each other so that their polarities are in the same direction, the phase-shift filter further includes a capacitor connected in parallel to the primary-side control coil and the second feedback coil. An output stabilization circuit as described in (1). (3) The secondary side circuit includes: a first power receiving coil that constitutes a transformer together with the first power transmitting coil; a second power receiving coil that constitutes a transformer together with the second power transmitting coil; and the first receiving coil and the second receiving coil are connected so that their coil voltages are in phase; The first feedback coil and the second feedback coil are magnetically coupled to each other so that their polarities are opposite to each other, the phase-shift filter further includes a capacitor connected in parallel to the primary-side control coil and the second feedback coil. An output stabilization circuit as described in (1). (4) The secondary side circuit includes: a first power receiving coil that constitutes a transformer together with the first power transmitting coil; a second power receiving coil that constitutes a transformer together with the second power transmitting coil; and the first receiving coil and the second receiving coil are connected so that their coil voltages are in phase; The first feedback coil and the second feedback coil are magnetically coupled to each other so that their polarities are in the same direction, the phase-shift filter further comprises a capacitor; the primary side control coil is connected in parallel to the capacitor and the second feedback coil of the phase shift filter; An output stabilization circuit as described in (1). (5) A DC-DC converter circuit including an output stabilization circuit according to any one of (1) to (4), The secondary side circuit includes: a first power receiving coil that constitutes a transformer together with the first power transmitting coil; a second power receiving coil that constitutes a transformer together with the second power transmitting coil; a DC conversion circuit that converts an AC voltage generated in the first power receiving coil and the second power receiving coil into a DC voltage; A DC-DC converter circuit having the above configuration. [Explanation of symbols]

[0059] 1 Power circuit 2 Primary circuit 3 Secondary circuit 10 Master Circuit 20 Slave Circuit BT Battery Device Q11, Q12, Q21, Q22 transistors N11, N12, N21, N22 transmit coils N31, N32 receiving coil Nf1, Nf2 feedback coil C11 Resonant capacitor B10, B20 bias circuit F20 Phase Shift Filter Lf21 Primary control coil Lc31 Secondary control coil SR30 rectifier circuit RV30, RV31 Reference Voltage Circuit Ic31 Shunt regulator element

Claims

1. An output stabilization circuit including a primary side circuit including a first self-oscillating circuit and a second self-oscillating circuit connected to a DC power source, and a secondary side circuit that obtains an output voltage by oscillation of the first self-oscillating circuit and the second self-oscillating circuit, The first self-oscillating circuit includes: A first power transmitting coil; a first resonant capacitor that configures a resonant circuit together with the first power transmitting coil; and a first switching element pair connected to the first power transmitting coil; a first feedback coil that is magnetically coupled to the first power transmission coil and connected to each control electrode of the first switching element pair; having The second self-oscillating circuit includes: A second power transmitting coil; and a second resonant capacitor that configures a resonant circuit together with the second power transmitting coil; and a second switching element pair connected to the second power transmitting coil; a second feedback coil magnetically coupled to the first feedback coil and connected to each control electrode of the second switching element pair; a phase-shift filter connected between the second feedback coil and each control electrode of the second switching element pair; having the secondary side circuit includes a secondary side control coil in which a magnitude of a current flowing therethrough is controlled in accordance with a magnitude of the output voltage; the phase shift filter includes a primary control coil that is magnetically coupled to the secondary control coil and has an inductance that changes in response to a current flowing through the secondary control coil; Output stabilization circuit.

2. The secondary side circuit includes: a first power receiving coil that constitutes a transformer together with the first power transmitting coil; a second power receiving coil that constitutes a transformer together with the second power transmitting coil; and The first receiving coil and the second receiving coil are connected so that the coil voltages are in opposite phases, The first feedback coil and the second feedback coil are magnetically coupled to each other so that their polarities are in the same direction, the phase-shift filter further includes a capacitor connected in parallel to the primary-side control coil and the second feedback coil.

2. The output stabilization circuit of claim 1.

3. The secondary side circuit includes: a first power receiving coil that constitutes a transformer together with the first power transmitting coil; a second power receiving coil that constitutes a transformer together with the second power transmitting coil; and the first receiving coil and the second receiving coil are connected so that their coil voltages are in phase; The first feedback coil and the second feedback coil are magnetically coupled to each other so that their polarities are opposite to each other, the phase-shift filter further includes a capacitor connected in parallel to the primary-side control coil and the second feedback coil.

2. The output stabilization circuit of claim 1.

4. The secondary side circuit includes: a first power receiving coil that constitutes a transformer together with the first power transmitting coil; a second power receiving coil that constitutes a transformer together with the second power transmitting coil; and the first receiving coil and the second receiving coil are connected so that their coil voltages are in phase; The first feedback coil and the second feedback coil are magnetically coupled to each other so that their polarities are in the same direction, the phase-shift filter further comprises a capacitor; the primary side control coil is connected in parallel to the capacitor and the second feedback coil of the phase shift filter; 2. The output stabilization circuit of claim 1.

5. A DC-DC converter circuit including the output stabilization circuit according to any one of claims 1 to 4, The secondary side circuit includes: a first power receiving coil that constitutes a transformer together with the first power transmitting coil; a second power receiving coil that constitutes a transformer together with the second power transmitting coil; a DC conversion circuit that converts an AC voltage generated in the first receiving coil and the second receiving coil into a DC voltage; A DC-DC converter circuit having the above configuration.

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