Output stabilizing circuit and dc-dc converter circuit

Abstract

The present application provides an output stabilization circuit and a DC-DC converter circuit. The output stabilization circuit (1) has a primary side circuit (2) and a secondary side circuit (3), the primary side circuit includes first and second self-oscillation circuits (10, 20) connected with a DC power supply (BT), the first and second self-oscillation circuits respectively include power transmission coils (N11, N12, N21, N22), resonance capacitors (C11, C21), switch element pairs (Q11, Q12, Q21, Q22) and feedback coils (Nf1, Nf2), and the second self-oscillation circuit (20) further includes a phase shift filter (F20) including a primary side control coil (Lf21) which is magnetically coupled with a secondary side control coil (Lc31) included in the secondary side circuit (3) and has a characteristic that the inductance varies according to the current flowing through the secondary side control coil.

Description

Technical Field

[0001] This invention relates to a self-oscillating circuit and a DC-DC (DCDC) converter circuit. Background Technology

[0002] There are simplified inverter circuits, power supply circuits, etc., which use self-excited oscillation circuits that differ from externally excited circuits and do not use control ICs, etc.

[0003] Patent Document 1 discloses a self-excited resonant power supply that controls the output voltage by supplying an error signal corresponding to the deviation of the voltage signal corresponding to the output voltage from the reference signal to the gates of the first transistor and the second transistor to change the self-excited oscillation frequency.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 11-285262 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] However, in the circuit described above, there are concerns that the application range may be narrowed due to the potential for the FET (Field Effect Transistor) to fall into unsaturation operation due to the rise and fall of the gate bias voltage, the deviation from the conditions for self-excited oscillation resulting in abnormal waveforms, and the increase in FET losses due to the increase in invalid current in the parallel resonant section.

[0009] This invention provides a circuit technique for stabilizing the output voltage conditionally through a simple circuit structure without interfering with conditions related to self-excited oscillation.

[0010] According to the present invention, an output stabilization circuit is provided, comprising: a primary-side circuit including a first self-excited oscillation circuit and a second self-excited oscillation circuit connected to a DC power supply; and a secondary-side circuit that obtains an output voltage through the oscillation of the first self-excited oscillation circuit and the second self-excited oscillation circuit, wherein the first self-excited oscillation circuit includes: a first power supply coil; a first resonant capacitor forming a resonant circuit together with the first power supply coil; a first pair of switching elements connected to the first power supply coil; and a first feedback coil magnetically coupled to the first power supply coil and connected to each control electrode of the first pair of switching elements; the second self-excited oscillation circuit includes: a second power supply coil; and a second resonant capacitor. The circuit comprises a second feedback coil, which together with the second power supply coil forms a resonant circuit; a second pair of switching elements, which is connected to the second power supply coil; a second feedback coil, which is magnetically coupled to the first feedback coil and connected to each control electrode of the second pair of switching elements; and a phase-shifting filter, which is connected between the second feedback coil and each control electrode of the second pair of switching elements. The secondary-side circuit includes a secondary-side control coil, which is controlled to control the magnitude of the current flowing through it according to the magnitude of the output voltage. The phase-shifting filter includes a primary-side control coil, which is magnetically coupled to the secondary-side control coil and has an inductance that varies according to the current flowing through the secondary-side control coil.

[0011] Based on the above method, a circuit technique can be provided to stabilize the output voltage conditionally through a simple circuit structure without interfering with conditions related to self-excited oscillation. Attached Figure Description

[0012] Figure 1 This is a circuit diagram of the power supply circuit in the first embodiment.

[0013] Figure 2 This is a circuit diagram of the secondary side circuit in a variation of the first embodiment.

[0014] Figure 3 This is a circuit diagram of the power supply circuit in the second embodiment.

[0015] Figure 4 This is a circuit diagram of the secondary side circuit of the power supply circuit in Example 1.

[0016] Figure 5 This is a graph showing the results of simulating voltage changes at various points in the power supply circuit of Example 1.

[0017] Figure 6 This is a graph showing the results of simulating voltage changes at various points in the power supply circuit of Example 1.

[0018] Figure 7 This is a graph showing the results of simulating voltage changes at various points in the power supply circuit of Example 1.

[0019] Figure 8 This is a circuit diagram of the secondary side circuit of the power supply circuit in Example 2.

[0020] Figure 9 This is a graph showing the results of simulating voltage changes at various points in the power supply circuit of Example 2.

[0021] Figure 10 This is a circuit diagram of the secondary side circuit of the power supply circuit in Example 3.

[0022] Figure 11 This is a graph showing the results of simulating voltage changes at various points in the power supply circuit of Example 3. Detailed Implementation

[0023] Hereinafter, examples of preferred embodiments of the present invention (hereinafter referred to as these embodiments) will be described. Furthermore, the embodiments listed below are merely illustrative examples, and the present invention is not limited to the structure of the embodiments described below.

[0024] [First Implementation Method]

[0025] Figure 1 This is a circuit diagram of the power supply circuit 1 in the first embodiment.

[0026] The power supply circuit 1 is a circuit that includes a primary-side circuit 2 with a battery device BT and a secondary-side circuit 3 that obtains an output voltage from the primary-side circuit 2, and stably provides an output to a load connected to the secondary-side circuit 3. In the first embodiment, an example is shown in which the battery device BT is configured as a battery device that supplies DC power, the secondary-side circuit 3 includes a DC conversion circuit, and the power supply circuit 1 as a whole functions as a DC-DC converter circuit.

[0027] [Primary side circuit]

[0028] The primary side circuit 2 also includes a main circuit 10 and a slave circuit 20 connected in parallel with the battery device BT.

[0029] The main circuit 10 includes power supply coils N11 and N12, a resonant capacitor C11, transistors Q11 and Q12 as a pair of switching elements, a bias circuit B10, a feedback coil Nf1, etc., which are used to form a self-excited oscillation circuit.

[0030] The power supply coils N11 and N12 are connected in series via an intermediate connector, which is connected to the positive terminal of the battery device BT via the input coil L11. Hereafter, when referring to one end of the power supply coil N11 or one end of the power supply coil N12, it refers to the end of the power supply coils N11 and N12 opposite to the intermediate connector side.

[0031] One end of the power supply coil N11 is connected to the negative terminal of the battery device BT via transistor Q11, and one end of the power supply coil N12 is connected to the negative terminal of the battery device BT via transistor Q12.

[0032] The resonant capacitor C11 is connected in parallel with the power transmission coils N11 and N12, and together they form a resonant circuit.

[0033] Transistors Q11 and Q12 are FETs (Field Effect Transistors), which can be represented as a pair of switching elements. The drain of transistor Q11 is connected to one end of the power supply coil N11, and the drain of transistor Q12 is connected to one end of the power supply coil N12. The sources of transistors Q11 and Q12 are connected to the negative terminal of the battery device BT. Additionally, the gates of transistors Q11 and Q12 are connected to the bias circuit B10.

[0034] The bias circuit B10 consists of resistors R11, R12, R13, and R14. The bias circuit B10 is connected in parallel with the battery device BT, applying bias voltages to the gates of transistors Q11 and Q12.

[0035] The feedback coil Nf1 is configured to be magnetically coupled to the power supply coils N11 and N12. One end of the feedback coil Nf1 is connected to the gate (control electrode) of transistor Q11, and the other end of the feedback coil Nf1 is connected to the gate (control electrode) of transistor Q12.

[0036] Except for the phase-shifting filter F20, the slave circuit 20 has the same structure as the main circuit 10. Specifically, the slave circuit 20 has power supply coils N21 and N22, a resonant capacitor C21, transistors Q21 and Q22 as a pair of switching elements, a bias circuit B20, a feedback coil Nf2, etc., which are used to form a self-excited oscillation circuit.

[0037] The power supply coils N21 and N22 correspond to the power supply coils N11 and N12 mentioned above; the resonant capacitor C21 corresponds to the resonant capacitor C11 mentioned above; the transistors Q21 and Q22 correspond to the transistors Q11 and Q12 mentioned above; the bias circuit B20 (resistors R21, R22, R23 and R24) corresponds to the bias circuit B10 (resistors R11, R12, R13 and R14) mentioned above; and the feedback coil Nf2 corresponds to the feedback coil Nf1 mentioned above.

[0038] Regarding these components of the slave circuit 20, descriptions of the same components (connection methods, etc.) as those in the main circuit 10 are appropriately omitted.

[0039] The feedback coil Nf2 of the slave circuit 20 is configured to be magnetically coupled to the power supply coils N11 and N12 in the main circuit 10 and to the feedback coil Nf1. Furthermore, the feedback coil Nf2 is magnetically coupled to the feedback coil Nf1 in such a manner that their polarities are in the same direction. Additionally, the feedback coil Nf2 is not magnetically coupled to the power supply coils N21 and N22 of the slave circuit 20.

[0040] In this embodiment, the power supply coil N11, power supply coil N12 and feedback coil Nf1 in the main circuit 10, and the feedback coil Nf2 of the slave circuit 20 together with the power receiving coil N31 of the secondary circuit 3 constitute a transformer (first transformer), and the power supply coils N21 and N22 of the slave circuit 20 together with the power receiving coil N32 of the secondary circuit 3 constitute a transformer (second transformer).

[0041] 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 supply power from the primary side circuit 2 to the secondary side circuit 3 by means of the electromagnetic induction of the first transformer and the second transformer.

[0042] A phase-shifting filter F20 is connected between the gates (control electrodes) of transistors Q21 and Q22 and the feedback coil Nf2. The phase-shifting filter F20 consists of a resistor Rf21, a primary-side control coil Lf21, and a capacitor Cf21, and can also be described as an RLC filter. The resistor Rf21 and the primary-side control coil Lf21 are connected in series with the feedback coil Nf2, and the capacitor Cf21 is connected in parallel with the feedback coil Nf2. Therefore, the phase-shifting filter F20 constitutes a low-pass filter.

[0043] The phase-shifting filter F20 functions by delaying the phase of the AC voltage generated in the feedback coil Nf2 due to the magnetic field generated in the first transformer caused by the current in the transmitting coil N11 or N12.

[0044] Furthermore, the primary-side control coil Lf21 of the phase-shifting filter F20 is magnetically coupled to the secondary-side control coil Lc31 of the secondary-side circuit 3 (described later), and has the characteristic that its inductance varies according to the current flowing through the secondary-side control coil Lc31. In this way, by making the inductance of the primary-side control coil Lf21 variable, the magnitude of the phase shift of the phase-shifting filter F20 becomes variable.

[0045] In addition to the structure described above, the primary side circuit 2 also includes a fuse FU and a capacitor C.

[0046] In the event of an excessive current generated due to an abnormality in the self-excited oscillation circuit (main circuit 10 and slave circuit 20) of the primary side circuit 2, the fuse FU disconnects the battery device BT from the primary side circuit 2. This prevents abnormal heating of the battery device BT caused by the excessive current.

[0047] The capacitor C absorbs the voltage changes caused by the charging and discharging of the battery device BT.

[0048] [Secondary side circuit]

[0049] The secondary side circuit 3 includes receiving coils N31 and N32, rectifier circuit SR30, and reference voltage circuit RV30.

[0050] As described above, the receiving coil N31 is configured as a secondary coil of the power supply coils N11 and N12 in the power supply circuit 1 as primary coils to form a transformer, and the current of the power supply coils N11 or N12 is used to generate an induced electromotive force.

[0051] As described above, the receiving coil N32 is configured as a secondary coil of the power supply coils N21 and N22 in the power supply circuit 1 as primary coils to form a transformer, and the current of the power supply coils N21 or N22 is used to generate an induced electromotive force.

[0052] The receiving coils N31 and N32 are connected in series to make their coil voltages out of phase. Therefore, theoretically, if the voltage induced in the receiving coil N31 is synchronized with the voltage induced in the receiving coil N32, the output is 0.

[0053] The rectifier circuit SR30 is connected to the receiving coils N31 and N32. SR30 includes a bridge rectifier circuit composed of diodes D31, D32, D33, and D34, and a smoothing filter composed of coil L31 and capacitor C31. SR30 functions as a full-wave rectifier circuit. That is, SR30 converts the AC voltage generated in the receiving coils N31 and N32 into DC voltage after full-wave rectification and smoothing.

[0054] The reference voltage circuit RV30 includes resistors R31 and R32, and a shunt regulator Ic31, and stabilizes the output voltage from the secondary side circuit 3 to a level above the reference voltage.

[0055] The shunt regulator element Ic31 receives the input voltage obtained by dividing the output voltage through resistors R31 and R32 at the reference terminal, and controls it to make the voltage between the reference and anode the reference voltage.

[0056] In addition, the reference voltage circuit RV30 also has a secondary-side control coil Lc31.

[0057] A current flows through the secondary-side control coil Lc31, corresponding to the voltage control of the shunt regulator element Ic31. That is, when the output voltage is higher than the reference voltage, the current flowing through the secondary-side control coil Lc31 increases, and when the output voltage is lower than the reference voltage, the current flowing through the secondary-side control coil Lc31 decreases.

[0058] The secondary control coil Lc31 is magnetically coupled to the primary control coil Lf21 as described above, and the inductance of the primary control coil Lf21 can be varied according to the amount of current flowing through the secondary control coil Lc31.

[0059] A transformer is formed by applying a common core as primary and secondary windings to the primary and secondary control coils Lf21, thus creating a single magnetic circuit. Furthermore, this transformer is configured, for example, to exhibit a DC superposition characteristic where the greater the DC current flowing through the secondary control coil Lc31, the greater the rate of inductance reduction in the primary control coil Lf21. Therefore, in the phase-shifting filter F20, according to the RLC filter characteristics, the greater the inductance value of the primary control coil Lf21, the greater the phase shift (the greater the phase difference between the output signal of the feedback coil Nf2 and the signal input to the gates of transistors Q21 and Q22).

[0060] Based on this structure, the phase shift of the phase-shifting filter F20 can be increased or decreased according to the output voltage from the secondary side circuit 3, thereby stabilizing the output voltage from the secondary side circuit 3.

[0061] The operation of the power supply circuit 1 in the first embodiment having the structure described above will now be explained.

[0062] In the main circuit 10, when DC power is supplied from the battery device BT to the bias circuit B10, the voltage divided by resistors R11 and R12 is applied as a bias voltage to the gate of transistor Q11, and the voltage divided by resistors R13 and R14 is applied as a bias voltage to the gate of transistor Q12. Therefore, based on the transistor characteristics and the resistance values ​​of resistors R11 and R13, one of transistors Q11 and Q12 will first become the on state.

[0063] At this time, with transistor Q11 in the on state, current flows through the power supply coil N11 and between the drain and source of transistor Q11.

[0064] As current flows through the primary winding N11, a magnetic field is generated in the first transformer, inducing an electromotive force (EMF) in the secondary winding N31. The induced EMF in the secondary winding N31 can be amplified according to the turns ratio of the primary winding N11 to the secondary winding N31.

[0065] 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, through self-induction.

[0066] When a back electromotive force is generated in the feedback coil Nf1, a negative voltage is applied to transistor Q11, causing the bias voltage applied to transistor Q11 to fall below the threshold voltage, and transistor Q11 becomes off. On the other hand, a positive voltage is applied to transistor Q12, causing the bias voltage applied to transistor Q12 to exceed the threshold voltage, and transistor Q12 becomes on.

[0067] When transistor Q11 is in the off state and transistor Q12 is in the on state, current flows through the power supply coil N12 and current flows between the drain and source of transistor Q12.

[0068] As current flows through the primary winding N12, a magnetic field is generated in the first transformer, and an induced electromotive force is generated in the secondary winding N31.

[0069] In this way, in the main circuit 10, by alternately repeating the on and off states of transistors Q11 and Q12, currents in different directions flow alternately through the power supply coils N11 and N12, which serve as the primary windings.

[0070] On the other hand, the same operation occurs in circuit 20. That is, when DC power is supplied from the battery device BT to the bias circuit B20, the voltage divided by resistors R21 and R22 is applied as a bias voltage to the gate of transistor Q21, and the voltage divided by resistors R23 and R24 is applied as a bias voltage to the gate of transistor Q22. Thus, depending on the transistor characteristics and the resistance values ​​of resistors R21 and R23, one of transistors Q21 and Q22 will first become the conducting state.

[0071] At this time, with transistor Q21 in the on state, current flows through the power supply coil N21 and between the drain and source of transistor Q21.

[0072] As current flows through the primary winding N21, a magnetic field is generated in the second transformer, inducing an electromotive force (EMF) in the secondary winding N32. The induced EMF in the secondary winding N32 can be amplified according to the turns ratio of the primary winding N21 to the secondary winding N32.

[0073] At this time, as described above, the same operation occurs in the main circuit 10. Due to the magnetic field generated in the first transformer of the main circuit 10, a back electromotive force is also generated in the feedback coil Nf2, which is the primary winding, through self-induction. Here, the voltage generated in the feedback coil Nf2 is phase-shifted by the phase-shifting filter F20 and applied to transistors Q21 and Q22. At this time, a negative voltage is applied to transistor Q21, so that the bias voltage applied to transistor Q21 becomes below the threshold voltage, and transistor Q21 becomes off. On the other hand, a positive voltage is applied to transistor Q22, so that the bias voltage applied to transistor Q22 exceeds the threshold voltage, and transistor Q22 becomes on.

[0074] When transistor Q21 is in the off state and transistor Q22 is in the on state, current flows through the power supply coil N22 and current flows between the drain and source of transistor Q22.

[0075] As current flows through the primary winding N22, a magnetic field is generated in the second transformer, which in turn induces an electromotive force in the secondary winding N32.

[0076] In this way, in circuit 20, by alternately repeating the on and off states of transistors Q21 and Q22, currents in different directions flow alternately through the power supply coils N21 and N22, which serve as the primary windings.

[0077] However, in circuit 20, the phase of the voltage generated in the feedback coil Nf2 is shifted by the phase-shifting filter F20. This causes the timing of the turn-on and turn-off of transistors Q21 and Q22 to shift relative to the timing of the turn-on and turn-off of transistors Q11 and Q12 in the main circuit 10. Consequently, the switching timing of the current in the power supply coils N21 and N22 shifts relative to the switching timing of the current in the power supply coils N11 and N12.

[0078] Through the operation of the primary circuit 2, a magnetic field is generated in the first and second transformers, and an alternating voltage consisting of alternating positive and negative voltages is induced in the secondary winding coils N31 and N32 in the secondary circuit 3.

[0079] However, as mentioned above, the switching timing of the current in the transmitting coils N21 and N22 is offset from the switching timing of the current in the transmitting coils N11 and N12. Therefore, the phase of the AC voltage induced in the receiving coil N31 is also offset from the phase of the AC voltage induced in the receiving coil N32.

[0080] In the secondary circuit 3, the AC voltage generated in the receiving coil N31 and the AC voltage generated in the receiving coil N32 are combined and input to the rectifier circuit SR30, where they are converted into DC voltage through full-wave rectification and smoothing.

[0081] When the converted DC voltage is input to the reference voltage circuit RV30, it is controlled by the shunt regulator element Ic31 to output a voltage above the reference voltage before being output.

[0082] At this time, a current corresponding to the output voltage flows through the secondary-side control coil Lc31. The inductance of the primary-side control coil Lf21, which is magnetically coupled to the secondary-side control coil Lc31, changes according to this current. As the inductance of the primary-side control coil Lf21 changes, the phase shift of the phase-shifting filter F20 also changes.

[0083] In this embodiment, the receiving coil N31 and the receiving coil N32 are connected in such a way that the coil voltages are out of phase. Therefore, the more synchronized (the more consistent the 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. The closer the phase offset is to 90 degrees, the higher the output voltage will be.

[0084] Therefore, when the current flowing through the secondary control coil Lc31 is large due to the action of the primary control coil Lf21, the resistor Rf21, and the capacitor Cf21, the phase-shifting filter F20 shifts the phase in the direction that synchronizes the AC voltages generated in the receiving coils N31 and N32. When the current is small, the phase-shifting filter F20 shifts the phase in the direction that shifts the phase of the AC voltages generated in the receiving coils N31 and N32.

[0085] Therefore, according to this embodiment, when the output voltage changes in accordance with the variation of the input DC voltage in a conventional collector resonant self-excited oscillation circuit, the output voltage can be stabilized with a simple circuit structure through such a phase shifting operation. Therefore, the power supply circuit 1 in this embodiment can be described as an output stabilization circuit.

[0086] [Modifications of the First Embodiment]

[0087] In the first embodiment described above, a power supply circuit 1 is shown as a DC-DC converter circuit that outputs a DC voltage. However, it is also possible to form a circuit structure that outputs a sinusoidal voltage by modifying the secondary side circuit 3.

[0088] Figure 2 This is a circuit diagram of the secondary side circuit 3 in a variation of the first embodiment. Furthermore, in this variation, the primary side circuit 2 can be... Figure 1 The first embodiment shown has the same structure.

[0089] In this modified example, the bridge rectifier circuit consisting of diodes D31, D32, D33, and D34 is removed from the secondary side circuit 3. Furthermore, the reference voltage circuit RV31, in addition to the structure of the reference voltage circuit RV30 in the first embodiment, also includes diode D35 and capacitor C32.

[0090] In the secondary circuit 3 of this variant, 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 synthesized and passed through low-pass filters (L31 and C31) to remove high-frequency noise components, and then input to the reference voltage circuit RV31.

[0091] In the reference voltage circuit RV31, the AC is rectified and smoothed by diode D35 and capacitor C32 to form DC. Therefore, it has the same function as the reference voltage circuit RV31 in the first embodiment, and can achieve output stabilization.

[0092] Therefore, according to this variant, a "stable sine wave output" can be obtained by taking the output from the low-pass filter (L31 and C31).

[0093] [Second Implementation]

[0094] Figure 3 This is a circuit diagram of the power supply circuit 1 in the second embodiment.

[0095] The power supply circuit 1 in the second embodiment differs from that in the first embodiment in that the receiving coils N31 and N32 are connected in the secondary side circuit 3 in such a way that the coil voltages are in phase, and the phase-shifting filter F20 is structured differently. The following description will focus on the differences between the power supply circuit 1 in the second embodiment and that in the first embodiment, while omitting content identical to that in the first embodiment as appropriate.

[0096] In the second embodiment, the receiving coil N31 and the receiving coil N32 are connected in such a way that the coil voltages are in phase. Therefore, the more synchronized (the more consistent the 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. The closer the phase offset is to 90 degrees, the lower the output voltage will be.

[0097] Therefore, when the current flowing through the secondary control coil Lc31 is large, the phase-shifting filter F20 needs to shift the phase in the direction that shifts the phase of the AC voltage generated in the receiving coils N31 and N32. When the current is small, the phase-shifting filter F20 needs to shift the phase in the direction that synchronizes the AC voltage generated in the receiving coils N31 and N32.

[0098] Therefore, in the phase-shifting filter F20 of the second embodiment, the second feedback coil Nf2 is connected in series with the capacitor Cf21, and the primary-side control coil Lf21 is connected in parallel with the second feedback coil Nf2 and the capacitor Cf21. That is, the phase-shifting filter F20 can perform the phase shifting as described above by constituting a high-pass filter.

[0099] Therefore, according to the second embodiment, even if the receiving coil N31 and the receiving coil N32 are connected in the secondary side circuit 3 in such a way that the coil voltages are in phase, the output voltage can be stabilized with a simple circuit structure in the same way as in the first embodiment.

[0100] [Modifications of the Second Embodiment]

[0101] When the receiving coils N31 and N32 are connected in the secondary circuit 3 such that their voltages are in phase, the structure of the phase-shifting filter F20 can also be the same as that in the first embodiment. In this case, it is sufficient to configure the feedback coils Nf1 and Nf2 to be magnetically coupled in opposite polarities.

[0102] In this way, the voltage induced in the feedback coil Nf1 can be out of phase with the voltage induced in the feedback coil Nf2. Therefore, even if the receiving coil N31 and the receiving coil N32 are connected in the secondary circuit 3 in such a way that the coil voltages are in phase, the same effect as in the first embodiment can be obtained.

[0103] The following examples illustrate the above content in more detail. However, the description of the following examples does not impose any limitations on the above content.

[0104] [Example 1]

[0105] In Example 1, the results obtained by simulating and verifying the effects of the first embodiment described above are shown.

[0106] Figure 4 This is a circuit diagram of the secondary side circuit 3 of the power supply circuit 1 in Embodiment 1.

[0107] In the simulation of Example 1, instead of controlling the inductance of the primary control coil Lf21 through magnetic coupling between the primary control coil Lf21 and the secondary control coil Lc31, the inductance value of the primary control coil Lf21 is virtually set manually.

[0108] Therefore, a reference voltage circuit RV30 is not provided in the secondary side circuit 3; instead, a load resistor R0 is connected. Furthermore, the primary side circuit 2 is connected to... Figure 1 The first embodiment shown has the same structure.

[0109] Figures 5 to 7 This is a graph showing the results of simulating voltage changes at various points in the power supply circuit 1 of Example 1. Figures 5 to 7 In the figure, (a) shows the simulation results when the inductance value of the primary control coil Lf21 is set to a first value, and (b) shows the simulation results when the inductance value of the primary control coil Lf21 is set to a second value that is larger than the first value.

[0110] exist Figure 5 (a) and Figure 5 In (b), the voltage waveform induced in the feedback coil Nf2 (output waveform), the voltage waveform induced in the feedback coil Nf2 and after being applied to the phase-shift filter F20 (after passing through the phase-shift filter F20), and the voltage waveform input to the gate of transistor Q22 are shown.

[0111] according to Figure 5As can be seen from (a), when the inductance value of the primary side control coil Lf21 is set to the 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.

[0112] On the other hand, according to Figure 5 As shown in (b), when the inductance value of the primary-side control coil Lf21 is set to the second (large) value, the phase shift of the phase-shifting filter F20 is compared to... Figure 5 As the case of (a) decreases, the phase of the voltage generated in the feedback coil Nf2 is slightly shifted by the phase-shifting filter F20 and applied to the gate of transistor Q22.

[0113] exist Figure 6 (a) and Figure 6 In (b), the voltage waveform between the drain and source of transistor Q12 in the main circuit 10 (output waveform) and the voltage waveform between the drain and source of transistor Q22 in the slave circuit 20 (output waveform) are shown.

[0114] according to Figure 6 As shown in (a), when the inductance value of the primary-side control coil Lf21 is set to the first value (small), the voltage waveform of transistor Q12 in the main circuit 10 is significantly out of phase with the voltage waveform of transistor Q22 in the slave circuit 20. This means that by increasing the phase shift of the voltage waveform generated in the feedback coil Nf2, the switching timing of transistors Q11 and Q12 in the main circuit 10 can be significantly out of phase with the switching timing of transistors Q21 and Q22 in the slave circuit 20.

[0115] On the other hand, according to Figure 6 As shown in (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 transistor Q12 in the main circuit 10 and the voltage waveform of transistor Q22 in the slave circuit 20 is small. This means that by reducing the phase shift of the voltage waveform generated in the feedback coil Nf2, the phase shift between the switching timing of transistors Q11 and Q12 in the main circuit 10 and the switching timing of transistors Q21 and Q22 in the slave circuit 20 can be reduced.

[0116] exist Figure 7 (a) and Figure 7 In (b), the DC voltage level applied to the load resistor and the full-wave rectified waveform on the cathode side of diode D33 are shown.

[0117] according to Figure 7As can be seen from (a), when the inductance value of the primary side control coil Lf21 is set to the first value (small), the phase of the voltage waveform generated in the receiving coil N31 is significantly offset from that of the voltage waveform generated in the receiving coil N32, and the DC voltage level of the synthesized voltage waveform after full-wave rectification becomes larger.

[0118] On the other hand, according to Figure 7 As shown in (b), when the inductance of the primary-side control coil Lf21 is set to the second (large) value, the phase difference between the voltage waveform generated in the current-receiving coil N31 and the voltage waveform generated in the current-receiving coil N32 is small. Therefore, the synthesized voltage waveform has a lower DC voltage level after full-wave rectification compared to... Figure 7 The case of (a) becomes smaller.

[0119] As shown in Embodiment 1, the following situation has been confirmed: In the power supply circuit 1 of the first embodiment, the phase shift of the phase shift filter F20 is changed by using the inductance value of the primary side control coil Lf21, thereby controlling the output voltage and stabilizing the output voltage.

[0120] [Example 2]

[0121] In Example 2, the results obtained by simulation to verify the effect of the modified example of the first embodiment described above are shown.

[0122] Figure 8 This is a circuit diagram of the secondary side circuit 3 of the power supply circuit 1 in Embodiment 2.

[0123] In the simulation of Example 2, the inductance value of the primary-side control coil Lf21 is virtually manually set, just like in Example 1.

[0124] Therefore, a reference voltage circuit RV30 is not provided in the secondary side circuit 3; instead, a load resistor R0 is connected. Furthermore, the primary side circuit 2 is connected to... Figure 1 The first embodiment shown has the same structure.

[0125] Figure 9 This is a graph showing the results of simulating voltage changes at various points in the power supply circuit 1 of Embodiment 2. Figure 9 (a) shows the simulation results when the inductance value of the primary-side control coil Lf21 is set to the first value. Figure 9 (b) shows the simulation results when the inductance value of the primary-side control coil Lf21 is set to a second value that is larger than the first value. Furthermore, the voltage waveforms at various points in the primary-side circuit 2 in Example 2 are similar to those in Example 1. Figure 5 and Figure 6 ) are the same.

[0126] exist Figure 9 (a) and Figure 9 In (b), the voltage waveform induced in the receiving coil N31 (output waveform), the voltage waveform induced in the receiving coil N32 (output waveform), and the voltage waveform of the load resistor are shown.

[0127] according to Figure 9 As can be seen from (a), when the inductance value of the primary control coil Lf21 is set to the first value (small), the phase of the voltage waveform generated in the receiving coil N31 is significantly offset from that of the voltage waveform generated in the receiving coil N32, and the synthesized voltage waveform becomes larger.

[0128] On the other hand, according to Figure 9 As shown in (b), when the inductance of the primary-side control coil Lf21 is set to the second (large) value, 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. Therefore, the synthesized voltage waveform is smaller than that of the primary-side control coil Lf21. Figure 9 The case of (a) becomes smaller.

[0129] As shown in Embodiment 2, it was confirmed that even when a structure with a secondary-side circuit 3 outputting a sinusoidal voltage is adopted, the output voltage can be stabilized in the power supply circuit 1 of the first embodiment by the phase-shifting operation of the phase-shifting filter F20.

[0130] [Example 3]

[0131] In Example 3, the results obtained by simulating and verifying the effects of the second embodiment described above are shown.

[0132] Figure 10 This is a circuit diagram of the secondary side circuit 3 of the power supply circuit 1 in Embodiment 3.

[0133] In Embodiment 3, unlike Embodiments 1 and 2, the receiving coils N31 and N32 are connected in such a way that the coil voltages are in phase. In the simulation of Embodiment 3, similar to Embodiment 1, the inductance value of the primary-side control coil Lf21 is virtually set manually. Therefore, instead of a reference voltage circuit RV30, a load resistor R0 is connected in the secondary-side circuit 3. Furthermore, the primary-side circuit 2 is... Figure 3 The second embodiment shown has the same structure.

[0134] Figure 11 This is a graph showing the results of simulating voltage changes at various points in the power supply circuit 1 of Embodiment 3. Figure 11 (a) shows the simulation results when the inductance value of the primary-side control coil Lf21 is set to the first value (small). Figure 11 (b) shows the simulation results when the inductance value of the primary side control coil Lf21 is set to a second value (larger) that is larger than the first value.

[0135] exist Figure 11 (a) and Figure 11 In (b), the voltage waveform between the drain and source of transistor Q12 in the main circuit 10 (output waveform), the voltage waveform between the drain and source of transistor Q22 in the slave circuit 20 (output waveform), and the DC voltage level applied to the load resistor are shown.

[0136] according to Figure 11 As can be seen from (a), when the inductance value of the primary side control coil Lf21 is set to the first value (small), the phase of the voltage waveform of transistor Q12 in the main circuit 10 and the voltage waveform of transistor Q22 in the slave circuit 20 are significantly offset, and the DC voltage level of the synthesized voltage waveform after full-wave rectification becomes smaller (2.4V).

[0137] On the other hand, according to Figure 11 As shown in (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 transistor Q12 in the main circuit 10 and the voltage waveform of transistor Q22 in the slave circuit 20 is small, and the synthesized voltage waveform has a lower DC voltage level after full-wave rectification compared to... Figure 11 The value of (a) increases (12.7V).

[0138] As shown in Embodiment 3, it was confirmed that in the power supply circuit 1 of the second embodiment, in which the receiving coil N31 and the receiving coil N32 are connected in such a way that the coil voltages are in phase, the output voltage can also be controlled by changing the phase shift of the phase shift filter F20 by using the magnitude of the inductance value of the primary side control coil Lf21, thereby achieving output voltage stabilization.

[0139] The above-described embodiments and modifications, in part or in whole, can also be determined as follows. However, the above-described embodiments and modifications are not limited to the following description.

[0140] (1) An output stabilization circuit comprising: a primary-side circuit including a first self-excited oscillation circuit and a second self-excited oscillation circuit connected to a DC power supply; and a secondary-side circuit that obtains an output voltage through the oscillation of the first self-excited oscillation circuit and the second self-excited oscillation circuit, wherein,

[0141] The first self-excited oscillation circuit has:

[0142] First power supply coil;

[0143] The first resonant capacitor, together with the first power supply coil, forms a resonant circuit;

[0144] A first pair of switching elements, which are connected to the first power supply coil; and

[0145] The first feedback coil is magnetically coupled to the first power supply coil and is connected to each control electrode of the first switching element pair.

[0146] The second self-excited oscillation circuit has:

[0147] Second power supply coil;

[0148] The second resonant capacitor, together with the second power supply coil, forms a resonant circuit;

[0149] The second pair of switching elements is connected to the second power supply coil;

[0150] The second feedback coil is magnetically coupled to the first feedback coil and is connected to each control electrode of the second switching element pair; and

[0151] A phase-shifting filter is connected between the second feedback coil and each control electrode of the second switching element pair.

[0152] The secondary-side circuit includes a secondary-side control coil, the magnitude of which is controlled by the magnitude of the output voltage to regulate the magnitude of the current flowing through the control coil.

[0153] The phase-shifting filter includes a primary-side control coil that is magnetically coupled to the secondary-side control coil and has an inductance that varies according to the current flowing through the secondary-side control coil.

[0154] (2) According to the output stabilization circuit described in (1), where,

[0155] The secondary side circuit also has:

[0156] A first receiving coil, which together with the first transmitting coil constitutes a transformer; and

[0157] The second receiving coil, together with the second transmitting coil, constitutes a transformer.

[0158] The first receiving coil and the second receiving coil are connected in such a way that the coil voltages are reversed.

[0159] The first feedback coil and the second feedback coil are magnetically coupled in such a way that their polarities are in the same direction.

[0160] The phase-shifting filter also includes a capacitor connected in parallel with the primary-side control coil and the second feedback coil.

[0161] (3) According to the output stabilization circuit described in (1), where,

[0162] The secondary side circuit also has:

[0163] A first receiving coil, which together with the first transmitting coil constitutes a transformer; and

[0164] The second receiving coil, together with the second transmitting coil, constitutes a transformer.

[0165] The first receiving coil and the second receiving coil are connected in such a way that the coil voltages are in phase.

[0166] The first feedback coil and the second feedback coil are magnetically coupled in such a way that their polarities are opposite.

[0167] The phase-shifting filter also includes a capacitor connected in parallel with the primary-side control coil and the second feedback coil.

[0168] (4) According to the output stabilization circuit described in (1), where,

[0169] The secondary side circuit also has:

[0170] A first receiving coil, which together with the first transmitting coil constitutes a transformer; and

[0171] The second receiving coil, together with the second transmitting coil, constitutes a transformer.

[0172] The first receiving coil and the second receiving coil are connected in such a way that the coil voltages are in phase.

[0173] The first feedback coil and the second feedback coil are magnetically coupled in such a way that their polarities are in the same direction.

[0174] The phase-shifting filter also includes a capacitor.

[0175] The primary-side control coil is connected in parallel with the capacitor and the second feedback coil of the phase-shifting filter.

[0176] (5) A DC-DC converter circuit, comprising an output stabilization circuit according to any one of (1) to (4), wherein,

[0177] The secondary side circuit has:

[0178] The first receiving coil, together with the first transmitting coil, constitutes a transformer;

[0179] The second receiving coil, together with the second transmitting coil, constitutes a transformer; and

[0180] A DC-DC converter circuit that converts the AC voltage generated in the first and second receiving coils into a DC voltage.

[0181] This application claims priority based on Japanese application filed on March 24, 2021 (Japan Patent Application No. 2021-49647), and incorporates all of its disclosures into this application.

Claims

1. An output stabilization circuit comprising: a primary-side circuit including a first self-excited oscillation circuit and a second self-excited oscillation circuit connected to a DC power supply; and a secondary-side circuit that obtains an output voltage through the oscillation of the first self-excited oscillation circuit and the second self-excited oscillation circuit, wherein, The first self-excited oscillation circuit has: First power supply coil; The first resonant capacitor, together with the first power supply coil, forms a resonant circuit; A first pair of switching elements is connected to the first power supply coil; as well as The first feedback coil is magnetically coupled to the first power supply coil and is connected to each control electrode of the first switching element pair. The second self-excited oscillation circuit has: Second power supply coil; The second resonant capacitor, together with the second power supply coil, forms a resonant circuit; The second pair of switching elements is connected to the second power supply coil; The second feedback coil is magnetically coupled to the first feedback coil and is connected to each control electrode of the second switching element pair; and A phase-shifting filter is connected between the second feedback coil and each control electrode of the second switching element pair. The secondary-side circuit includes a secondary-side control coil, the magnitude of which is controlled by the magnitude of the output voltage to regulate the magnitude of the current flowing through the control coil. The phase-shifting filter includes a primary-side control coil that is magnetically coupled to the secondary-side control coil and has an inductance that varies according to the current flowing through the secondary-side control coil.

2. The output stabilization circuit according to claim 1, wherein, The secondary side circuit also has: A first receiving coil, which together with the first transmitting coil constitutes a transformer; and The second receiving coil, together with the second transmitting coil, constitutes a transformer. The first receiving coil and the second receiving coil are connected in such a way that the coil voltages are reversed. The first feedback coil and the second feedback coil are magnetically coupled in such a way that their polarities are in the same direction. The phase-shifting filter also includes a capacitor connected in parallel with the primary-side control coil and the second feedback coil.

3. The output stabilization circuit according to claim 1, wherein, The secondary side circuit also has: A first receiving coil, which together with the first transmitting coil constitutes a transformer; and The second receiving coil, together with the second transmitting coil, constitutes a transformer. The first receiving coil and the second receiving coil are connected in such a way that the coil voltages are in phase. The first feedback coil and the second feedback coil are magnetically coupled in such a way that their polarities are opposite. The phase-shifting filter also includes a capacitor connected in parallel with the primary-side control coil and the second feedback coil.

4. The output stabilization circuit according to claim 1, wherein, The secondary side circuit also has: A first receiving coil, which together with the first transmitting coil constitutes a transformer; and The second receiving coil, together with the second transmitting coil, constitutes a transformer. The first receiving coil and the second receiving coil are connected in such a way that the coil voltages are in phase. The first feedback coil and the second feedback coil are magnetically coupled in such a way that their polarities are in the same direction. The phase-shifting filter also includes a capacitor. The primary-side control coil is connected in parallel with the capacitor and the second feedback coil of the phase-shifting filter.

5. A DC-DC converter circuit, comprising the output stabilization circuit according to any one of claims 1 to 4, wherein, The secondary side circuit has: The first receiving coil, together with the first transmitting coil, constitutes a transformer; The second receiving coil, together with the second transmitting coil, constitutes a transformer; and A DC-DC converter circuit that converts the AC voltage generated in the first and second receiving coils into a DC voltage.

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