JP3654000B2 - Self-excited resonant inverter circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a resonant circuit of an inductor and a resonant capacitor and a switching element, and performs on / off control of the switching element using an electromotive force obtained from a feedback inductor that is magnetically coupled to the inductor. The present invention relates to a self-excited resonant inverter circuit that converts the direct current power into high frequency alternating current power.
[0002]
[Prior art]
In recent years, resonant inverter technology that reduces the switching loss by making the voltage (current) to the switching element sinusoidal has been rapidly put into practical use because it has higher efficiency and lower noise than the conventional hard switching method. It is coming.
[0003]
In a method using this type of resonant inverter technology, it is necessary to realize so-called zero voltage switching in which the switching element is turned on when the sinusoidal voltage to the switching element approaches zero, and the ON period of the switching element Must be controllable to stabilize the output. In general, in order to realize these, the voltage to the switching element is monitored, the switching element is turned on according to the monitoring result, and then the switching element is turned off after a lapse of a predetermined time such as a timer, A method of detecting a signal of a portion to be stabilized in the circuit and controlling the ON period of the switching element according to the detection result is adopted.
[0004]
However, in the above method, a voltage to the switching element is monitored, and a circuit for turning on the switching element according to the monitoring result, a circuit for managing the on period of the switching element, and another control circuit for controlling the on period are provided. Therefore, the number of parts increases, the circuit becomes complicated, and the cost increases.
[0005]
As a system for solving such a problem, there is a self-excited oscillation circuit system that realizes zero voltage switching with a simple circuit using a bias circuit and a feedback inductor.
[0006]
FIG. 9 is a schematic configuration diagram of a conventional self-excited resonant inverter circuit showing an example of such a self-excited oscillation circuit system. This self-excited resonant inverter circuit is used for starting a field effect transistor (FET) Q12. A starter circuit 11, a DC / AC converter circuit 12 including a FET Q12, a primary winding L12 of a transformer T1, a resonance capacitor C12, and the like, which converts DC power from a DC power source E into high-frequency AC power, and a transformer T1 are provided. The ON control circuit 13 that turns on the FET Q12 using the electromotive force obtained from the feedback winding L13, and the primary winding L12 in the ON period of the FET Q12. Resistor R14pa which detects the increase in the above current by increasing the voltage, and turns on when the voltage of this resistor R14pa reaches the turn-on threshold. And an off control circuit 14pa including a transistor Q14 for turning off Q12.
[0007]
This type of circuit configuration is disclosed in, for example, Japanese Patent Laid-Open No. 9-322416.
[0008]
As shown in FIG. 10, another method using an auxiliary switching element such as the transistor Q14 is described in Japanese Patent Laid-Open No. 5-304773. In this circuit using the transistor Q2pa as the auxiliary switching element, when a positive voltage is applied to the capacitor C1pa through the resistor R1pa by the electromotive force induced in the feedback winding L1pa, the voltage of the capacitor C1pa increases. When the transistor reaches the turn-on threshold value of the transistor Q2pa, the transistor Q2pa is turned on and the main transistor Q1pa is turned off.
[0009]
[Problems to be solved by the invention]
However, the self-excited resonant inverter circuit of FIG. 9 is a very simple and reliable circuit system when used at a low output, but is used for detecting an increase in current when used at a high output. Since the loss at the resistor R14pa increases, it is necessary to take measures against heat dissipation.
[0010]
On the other hand, in the circuit shown in FIG. 10, the above heat dissipation measure is not necessary, but another problem arises. That is, when a negative voltage is applied to the capacitor C1pa via the resistor R1pa by the electromotive force induced in the feedback winding L1pa, the charge of the capacitor C1pa is instantaneously discharged via the diode D1pa, and the voltage of the capacitor C1pa is fed back. It becomes almost equal to the negative voltage of the winding L1pa. For this reason, the base voltage of the transistor Q2pa is greatly reduced negatively, and the transistor Q2pa may be destroyed. In this circuit system, the charging period is inversely proportional to the voltage of the feedback winding L1pa, and the voltage output of the main winding is automatically stabilized by the negative feedback action. When stabilizing the output, when stabilizing other parts such as output current, or when changing the output over time, such as charging to a secondary battery, where the current is initially large and then small. It is not available.
[0011]
The present invention has been made in view of the above circumstances, and does not require a heat dissipation measure for resistance loss even at high output, and can easily realize output stabilization control and variable output control as needed. An object is to provide a type inverter circuit.
[0012]
[Means for Solving the Problems]
  A self-excited resonant inverter circuit according to the present invention for solving the above-described problems is interposed in a main switching element that turns on / off between both output terminals of a DC power supply, and on a path that the main switching element turns on / off. An inductor, a resonance capacitor that forms a resonance circuit together with the inductor, a DC / AC conversion circuit that converts DC power from the DC power source into high-frequency AC power, and a feedback inductor that is magnetically coupled to the inductor An on-control circuit that turns on the main switching element using electromotive force, two diodes connected in reverse parallel, two resistors that form a series circuit with each of the two diodes, the inductor, and the magnetic field An off-control capacitor having one end connected to one end of the coupled feedback inductor through the two series circuits. A diode having an anode connected to one end side of the off-control capacitor, and an auxiliary switching element connected to the cathode side of the diode, and the main switching element is turned on according to the charging time of the off-control capacitor An off control circuit that controls the on period from the off time to the off time, and the auxiliary switching element turns off the main switching element when the on period elapses;A power supply for supplying power to the off-control capacitor;Is provided.
[0013]
  In this configuration, since there is no single resistor, for example, on the path where the main switching element is turned on / off, no heat dissipation measures against the loss at the resistor are required even at high output. Further, when a voltage is separately applied to the off-control capacitor, the on-period of the main switching element is shortened, so that it becomes easy to realize output stabilization control and variable output control as necessary.Further, in this configuration, the on-period of the main switching element is adjusted by appropriately applying a bias voltage from the power source to the off-control capacitor.
[0014]
The on-control circuit includes a first feedback inductor as the feedback inductor for obtaining an electromotive force used to turn on the main switching element, and the off-control circuit includes the two series circuits. A configuration may be adopted in which a second feedback inductor is provided as the feedback inductor connected to the off-control capacitor. This configuration also eliminates the need for heat dissipation countermeasures for resistance loss even at high output, and facilitates output stabilization control and variable output control as required.
[0015]
Further, both the on control circuit and the off control circuit may share a feedback inductor magnetically coupled to the inductor by the same feedback inductor. According to this configuration, it is not necessary to take heat dissipation measures against resistance loss even at high output, and it becomes easy to realize output stabilization control and variable output control as necessary. Further, since the same feedback inductor is shared, the size can be reduced.
[0016]
Further, a discharge voltage clamping diode having a cathode and an anode connected to one end and the other end of the off-control capacitor may be used. According to this configuration, the voltage of the auxiliary switching element is prevented from being greatly stepped down in the negative direction.
[0017]
In addition, a configuration in which a positive voltage of the electromotive force generated by the magnetic coupling is made constant and applied to the off-control capacitor via the two sets of series circuits may be provided. According to this configuration, the off control of the main switching element is stabilized.
[0019]
The power source includes a detection circuit that detects a signal for on-period adjustment control of the main switching element, and a control circuit that supplies power to the off-control capacitor according to a detection result of the detection circuit. But you can. In this configuration, the ON period of the main switching element is automatically adjusted.
[0020]
The main switching element may be one stone, and the resonance capacitor may be connected in parallel to the inductor. According to this configuration, it is not necessary to take heat dissipation measures against resistance loss even at high output, and it becomes easy to realize output stabilization control and variable output control as necessary.
[0021]
Further, the DC / AC converter circuit, the ON control circuit, and the OFF control circuit are provided in two sets, the inductor of the DC / AC converter circuit in one of the two sets, the feedback inductor used in the ON control circuit, and the OFF control. The feedback inductors used in the circuit have polarities with respect to the feedback inductor used in the on-control circuit and the feedback inductor used in the off-control circuit, respectively, in the DC / AC converter circuit in the other of the two sets. Conversely, the two sets of resonance capacitors may be connected in parallel to inductors in the same set. According to this configuration, it is not necessary to take heat dissipation measures against resistance loss even at high output, and it becomes easy to realize output stabilization control and variable output control as necessary. In addition, a push-pull circuit type configuration is possible.
[0022]
Further, the circuit has two each of the on control circuit and the off control circuit, and the DC / AC conversion circuit is turned on / off between the output terminals of another DC power supply connected in series with the main switching element and the DC power supply. Another main switching element that performs switching, a resonance capacitor that is connected in parallel to each of the two stone main switching elements, and one of the two stone main switching elements that is interposed on a path for turning on / off, and the 2 The other of the stone main switching elements has an inductor interposed on a path for turning on / off, and the two on-control circuits respectively generate the electromotive force obtained from the feedback inductor by the two stone main switching elements. Each of the two off control circuits controls the on period of the two stone main switching elements and the two stone main switches. The switching element is turned off when the on-period has elapsed, and the polarity of the feedback inductor used in one of the two on-control circuits is opposite to that of the feedback inductor used in the other of the two on-control circuits. The feedback inductor used in one of the two off control circuits may have a polarity opposite to that of the feedback inductor used in the other of the two off control circuits. According to this configuration, measures for heat dissipation are not required, and output stabilization control and variable output control according to need can be easily realized. In addition, a half-bridge circuit configuration is possible.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic configuration diagram showing a self-excited resonant inverter circuit according to a first embodiment of the present invention. Hereinafter, the self-excited resonant inverter circuit will be described with reference to FIG. The circuit 11, the DC / AC conversion circuit 12, and the ON control circuit 13 are provided in the same manner as in FIG. 9, and the OFF control circuit 14 having a circuit configuration different from that of the OFF control circuit 14pa in FIG. The DC power supply E may be a power supply circuit that obtains DC power by rectifying and smoothing the power from the AC power supply, or may be a battery, a polyacene secondary battery, or the like.
[0024]
The starting circuit 11 includes a resistor R11 having one end connected to the high potential side output end of the DC power source E and a capacitor C11 connected between the other end of the resistor R11 and the low potential side output end of the DC power source E. The FET Q12 is turned on by the voltage generated in the capacitor C11 at the time of startup. However, the voltage of the capacitor C11 is applied to the gate of the FET Q12 via a feedback winding L13 and a resistor R13, which will be described later.
[0025]
The DC / AC converter circuit 12 includes an FET (main switching element) Q12 that turns on and off between both output terminals of the DC power supply E, and a transformer T1 that is interposed on the high potential side on the path that the FET Q12 turns on and off. A secondary winding (inductor) L12, a resonance capacitor C12 that is connected in parallel to the primary winding L12 and forms a resonance (voltage resonance) circuit with the primary winding L12, and an anode and a cathode are 1 on each of the paths. It is composed of a secondary winding L12 and a diode D12 connected to the drain of the FET Q12, a resistor R12 connected in parallel to the diode D12, and a secondary winding L15 of the transformer T1. This is converted into electric power and output to both ends of the secondary winding L15.
[0026]
The ON control circuit 13 includes a feedback winding (first feedback inductor) L13 provided at the transformer T1 (primary side in FIG. 1) and having one end connected between the resistor R11 and the capacitor C11, and the feedback winding L13. Is configured by a resistor R13 connected between the other end of the FET Q12 and the gate of the FET Q12, and turns on the FET Q12 using an electromotive force obtained from the feedback winding L13.
[0027]
The off control circuit 14 includes two diodes D141 and D142 connected in parallel in reverse (in such a manner that the forward directions are opposite to each other), and two resistors R141 that form a series circuit with the two diodes D141 and D142, respectively. , R142, a feedback winding (second feedback inductor) L14 having one end and the other end connected to one end and the ground of the two series circuits provided in the transformer T1, and the two ends connected to one end of the feedback winding L14. The other end grounded off control capacitor C141 having one end connected through a series circuit of the set, the diode D143 having an anode connected to one end side of the off control capacitor C141, and one end and the other end of the off control capacitor C141 Are connected to the cathode and anode of the discharge voltage clamp diode D144 and FET Q1, respectively. A diode D145 whose anode is connected to the gate of the diode, a grounded-emitter transistor (auxiliary switching element) Q14 whose base and collector are connected to the cathodes of the diodes D143 and D145, respectively, and a base-emitter of the transistor Q14 The capacitor C142 is configured to control the ON period from the ON time point to the OFF time point of the FET Q12 according to the charging time of the OFF control capacitor C141, and when the ON period elapses, the transistor Q14 is turned ON and the FET Q12 is turned OFF. To do. However, the diode D144 clamps the negative potential of the off-control capacitor C141 to about minus 0.7 V corresponding to the forward voltage of the diode D144, and suppresses the base voltage of the transistor Q14 from being greatly stepped down in the negative direction. Is for.
[0028]
As shown in FIG. 1, when the polarity of one end connected to the high potential side output end of the DC power source E is positive among both ends of the primary winding L12, the feedback winding L13 is connected to the other end (see FIG. 1). 1 is wound around the transformer T1 so that the polarity at the lower end) is positive, and is magnetically coupled to the primary winding L12, while the feedback winding L14 has a positive polarity at one end (the upper end in FIG. 1). Thus, it is wound around the transformer T1 and magnetically coupled to the primary winding L12.
[0029]
FIG. 2 shows the voltage Vd on the FET Q12 side of the primary winding L12, the drain current Id flowing through the FET Q12, the gate voltage Vg of the FET Q12, the base voltage Vb of the transistor Q14, and the off-control capacitor during the operation of the self-excited resonant inverter circuit. The operation of the self-excited resonance type inverter circuit will be described below with reference to FIG.
[0030]
First, the operation from the time of turning on the power to time t0 will be described. When the power is turned on, the output voltage of the DC power supply E is applied to the starter circuit 11, the voltage of the capacitor C11 increases, and the gate voltage of the FET Q12 increases. Thereafter, when the gate voltage of the FET Q12 reaches its turn-on threshold, the FET Q12 is turned on.
[0031]
When the FET Q12 is turned on, the current flows while increasing in this order on the path of the DC power supply E, the primary winding L12, the diode D12, the FET Q12, and the DC power supply E. By this current, the primary winding L12 is positively excited and a positive electromotive force is induced in the feedback winding L14. As a result, a positive voltage is applied to the off-control capacitor C141 from the feedback winding L14 via one (upper in FIG. 1) series circuit, the voltage of the off-control capacitor C141 rises, and the base voltage of the transistor Q14 becomes Rise. Thereafter, when the base voltage of the transistor Q14 reaches its turn-on threshold, the transistor Q14 is turned on and the FET Q12 is turned off (time point t0).
[0032]
Next, the operation from time t0 to time t1 will be described. When the FET Q12 is turned off (time t0), the excitation energy of the primary winding L12 starts to move to the resonance capacitor C12, resonance starts, and a resonance voltage is generated in the resonance circuit. That is, as the excitation energy of the primary winding L12 moves to the resonance capacitor C12, the voltage Vd rises in a sine wave shape, and becomes maximum when the movement of the excitation energy is completed. When such voltage fluctuation occurs, the primary winding L12 is excited in the reverse direction, and a reverse electromotive force is induced in the feedback windings L13 and L14. As a result, a reverse voltage is applied from the feedback winding L13, and the gate voltage Vg of the FET Q12 falls in a sine wave shape. On the other hand, a reverse voltage is also generated in the feedback winding L14, and the off-control capacitor C141 starts to discharge through the lower series circuit, so that the base voltage Vb of the transistor Q14 decreases.
[0033]
Thereafter, when the base voltage Vb of the transistor Q14 becomes lower than the turn-on threshold value, the transistor Q14 is turned off. On the other hand, the gate voltage Vg of the FET Q12 also becomes lower than the turn-on threshold value. .
[0034]
Thereafter, when the movement of the excitation energy of the primary winding L12 to the resonance capacitor C12 is completed, the moved energy starts to return to the primary winding L12, and the voltage Vd decreases in a sine wave shape as it returns. When such a voltage fluctuation occurs, the primary winding L12 is positively excited and a positive electromotive force is induced in the feedback windings L13 and L14. As a result, a positive voltage is applied from the feedback winding L13, and the gate voltage Vg of the FET Q12 rises in a sine wave shape. On the other hand, a positive voltage is applied from the feedback winding L14 to the off-control capacitor C141 side, but the induced electromotive force does not increase the voltage of the off-control capacitor C141.
[0035]
Thereafter, when the gate voltage Vg of the FET Q12 reaches the turn-on threshold (time point t1), the FET Q12 is turned on. At this time, since the FET Q12 is turned on at the time t1 when the sine wave voltage Vd to the FET Q12 approaches zero, zero voltage switching is realized.
[0036]
Next, although it is already clear, the operation from time t1 to time t2 will be outlined. When the FET Q12 is turned on (time point t1), the drain current Id flows, the primary winding L12 is excited positively, and a positive electromotive force is induced in the feedback winding L14. A positive voltage is applied to capacitor C141, voltage Vc of off-control capacitor C141 rises, and base voltage Vb of transistor Q14 rises. Thereafter, when the base voltage Vb of the transistor Q14 reaches its turn-on threshold (time t2), the transistor Q14 is turned on and the FET Q12 is turned off.
[0037]
Finally, the operation from time t2 to time t4 will be outlined. When the FET Q12 is turned off (time point t2), the excitation energy of the primary winding L12 starts to move to the resonance capacitor C12, and the primary winding L12 is reversely excited to reverse the electromotive force in the feedback windings L13 and 14. Is induced. As a result, a reverse voltage is applied from the feedback winding L13, and the gate voltage Vg of the FET Q12 falls in a sine wave shape. On the other hand, a reverse voltage is generated in the feedback winding L14, the off-control capacitor C141 starts discharging, and the base voltage Vb of the transistor Q14 decreases.
[0038]
Thereafter, when the base voltage Vb of the transistor Q14 becomes lower than the turn-on threshold, the transistor Q14 is turned off, while the FET Q12 is kept off. Thereafter, the discharge of the off-control capacitor C141 is completed (time point t3).
[0039]
Thereafter, when the movement of the excitation energy of the primary winding L12 to the resonance capacitor C12 is completed, the moved energy starts to return to the primary winding L12, and as it returns, the voltage Vd decreases in a sine wave shape, and the primary winding. The line L12 is positively excited and a positive electromotive force is induced in the feedback winding L13. As a result, a positive voltage is applied from the feedback winding L13, the gate voltage Vg of the FET Q12 rises in a sine wave shape, and when the turn-on threshold value is reached, the FET Q12 is turned on (time point t4). In this way, the inverter operation continues.
[0040]
As described above, according to the first embodiment, since there is no resistance through which the drain current flows directly when the FET Q12 is turned on, it is possible to eliminate the need for heat dissipation countermeasures for resistance loss even at high output. Further, when a voltage is separately applied to the off-control capacitor, the on-period of the main switching element is shortened, so that output stabilization control and variable output control as necessary can be easily realized, as will be described later. Furthermore, zero voltage switching is possible with a small number of components.
[0041]
In the first embodiment, the transformer T1 is used. However, the present invention is not limited to this, and the primary winding L12 and the non-contact charging device described in JP-A-9-322416 are not limited thereto. The secondary winding L15 may be replaced with two coils that are magnetically coupled in a non-contact manner, and the feedback windings L13 and L14 may be replaced with two coils that are magnetically coupled with a coil that replaces the primary winding L12. Good.
[0042]
FIG. 3 is a schematic configuration diagram showing a self-excited resonant inverter circuit according to a second embodiment of the present invention. The second embodiment will be described below with reference to FIG. 3. The self-excited resonant inverter circuit is activated. The circuit 11, the DC / AC converter circuit 12, and the on control circuit 13 are provided in the same manner as in the first embodiment, and an off control circuit 24 having a circuit configuration different from that of the off control circuit 14 in the first embodiment is provided.
[0043]
Similar to the off control circuit 14, the off control circuit 24 includes diodes D141 and D142, resistors R141 and R142, off control capacitors C141, diodes D143 to D145, a transistor Q14, and a capacitor C142. 14 is a low-voltage diode ZD241 having a cathode and an anode connected to one end and ground of two sets of series circuits, respectively, and between the cathode of the low-voltage diode ZD241 and the feedback winding L13 on the resistor R13 side. A resistor R241 connected to the.
[0044]
The low voltage diode ZD241 and the resistor R241 make the positive voltage of the electromotive force from the feedback winding L13 constant, and the off-control capacitor C141 via the two sets of series circuits (specifically, the upper series circuit). A constant voltage circuit to be applied to is configured.
[0045]
The operation of this constant voltage circuit will be described. When a positive electromotive force corresponding to the drain current is induced in the feedback winding L13 instead of the feedback winding L14, the constant voltage circuit causes the feedback winding L13 to turn off. A constant positive voltage is applied to the capacitor C141 side, and the off control of the FET Q12 by the off control circuit 24 is stabilized.
[0046]
Since the operation of the feedback winding L13 with respect to the off control circuit 24 is the same as that of the feedback winding L14 of the first embodiment, the operation of the self-excited resonant inverter circuit of the first embodiment is the same as that of the first embodiment. It becomes the same operation of.
[0047]
As described above, according to the second embodiment, the same effect as that of the first embodiment can be obtained, and the feedback winding L14 is not required, so that the size can be reduced and the constant voltage circuit can stabilize the circuit. The FET Q12 can be turned off.
[0048]
FIG. 4 is a schematic configuration diagram showing a self-excited resonant inverter circuit according to a third embodiment of the present invention. Hereinafter, the self-excited resonant inverter circuit will be described with reference to FIG. The circuit 11, the DC / AC conversion circuit 12, the on control circuit 13 and the off control circuit 14 are provided in the same manner as in the first embodiment, and for the off control via the diode D 35, the resistor R 35, and the diode D 35 and the resistor R 35. A voltage source (power source) 35 for appropriately applying (supplying) a bias voltage (power) to the capacitor C141 is provided.
[0049]
Next, the operation of the voltage source 35 will be described. When the voltage source 35 applies a bias voltage to the off-control capacitor C141 side, the time until the base voltage of the transistor Q14 reaches the turn-on threshold is shortened, thereby shortening the on-period of the FET Q12.
[0050]
As described above, according to the third embodiment, since the same operation as in the first embodiment can be performed, the same effect can be obtained, and the bias voltage from the voltage source 35 is appropriately applied to the off-control capacitor C141. As a result, adjustment control of the ON period of the FET Q12 becomes possible.
[0051]
FIG. 5 is a schematic configuration diagram showing a self-excited resonant inverter circuit according to a fourth embodiment of the present invention. Hereinafter, the self-excited resonant inverter circuit will be described with reference to FIG. The circuit 11, the DC / AC converter circuit 12, the on control circuit 13, and the off control circuit 14 are provided in the same manner as in the first embodiment, and a bias voltage is applied to the off control capacitor C141 via the diode D45 and the diode D45. An applied voltage source (power source) 45 is provided.
[0052]
The voltage source 45 includes an output information detection circuit (detection circuit) 451 that detects output information from, for example, an output part of the DC / AC conversion circuit 12 as an on-period adjustment control signal of the FET Q12, and the output information detection circuit 451. The control circuit 452 is configured to generate a voltage for adjusting the ON period of the FET Q12 according to the detection result and apply the voltage to the OFF control capacitor C141 via the diode D45.
[0053]
Next, the operation of the voltage source 45 will be described. A voltage obtained according to the output information of the DC / AC conversion circuit 12 is applied to the off-control capacitor C141 via the diode D45. As a result, the time until the voltage of the off-control capacitor C141 reaches the turn-on threshold value of the transistor Q14 is shortened and the on-period of the FET Q12 is shortened, so that the on-state of the FET Q12 corresponding to the output information of the DC / AC converter circuit 12 is shortened. Automatic adjustment control of the period becomes possible.
[0054]
As described above, according to the fourth embodiment, since the same operation as in the first embodiment can be performed, the same effect can be obtained, and the automatic adjustment control of the ON period of the FET Q12 can be performed.
[0055]
In the fourth embodiment, the output information is detected from the output unit of the DC / AC converter circuit 12 as a signal for on-period adjustment control of the FET Q12. However, the detected portion is arbitrary. . For example, the drain current of the FET Q12 may be detected as a signal for controlling the ON period of the FET Q12, and the ON period of the FET Q12 may be adjusted and controlled according to the detection result.
[0056]
FIG. 6 is a schematic configuration diagram showing a self-excited resonance inverter circuit according to a fifth embodiment of the present invention. The fifth embodiment will be described below with reference to FIG. Each of the starter circuits 11, a DC / AC converter circuit 52 substantially corresponding to two DC / AC converter circuits 12, two on-control circuits 13, and two off-control circuits 14 are provided.
[0057]
The DC / AC converter circuit 52 is a primary winding in which two stone FETs (main switching elements) Q52, two resonance capacitors C52, and two portions separated by a center tap correspond to two primary windings L12. The line L52 and the two parts separated by the center tap are constituted by secondary windings L55 corresponding to two secondary windings L15.
[0058]
Then, one part (inductor) of the primary winding L52, the feedback winding L13, and the feedback winding L14 in one of the two sets (upper set in FIG. 6) constituted by the above circuits are each provided in two sets. The other part (inductor) of the primary winding L52 (inductor) in the other side (inductor), the feedback winding L13 and the feedback winding L14 have opposite polarities, and the two sets of resonance capacitors C52 are It is connected in parallel to a part of the primary winding L52 in the same set. Note that a load Z is connected to the output of the self-excited resonance type inverter circuit via two diodes D51 and 52 and a capacitor C51.
[0059]
With this configuration, the self-excited resonant inverter circuit substantially equivalent to the self-excited resonant inverter circuit of the first embodiment corresponding to two performs the push-pull operation, and the push-pull circuit system Can be configured.
[0060]
As described above, according to the fifth embodiment, since the self-excited resonant inverter circuit is substantially constituted by the two self-excited resonant inverter circuits of the first embodiment, the same effects as the first embodiment are achieved. As well as a push-pull circuit configuration.
[0061]
FIG. 7 is a schematic configuration diagram showing a self-excited resonance inverter circuit according to a sixth embodiment of the present invention. The sixth embodiment will be described below with reference to FIG. In addition to the capacitors C 1 and C 2, the two diodes D 61, and the DC / AC conversion circuit 62, each of the start circuit 11, the on control circuit 13, and the off control circuit 14 is provided. Note that a load Z is connected to the output of the self-excited resonance type inverter circuit through two diodes D51 and 52 and a capacitor C51, as in the sixth embodiment.
[0062]
Capacitors C1 and C2 are connected in series between the output terminals of the DC power supply E, and are set so that half the voltage of the DC power supply E is generated in each.
[0063]
Each diode D61 has an anode connected between the resistor R11 and the capacitor C11, and a cathode connected to the drain of the FET Q62 described later, so that the on-time of the FET Q62 does not become too long. That is, when the voltage of the capacitor C11 maintains the turn-on voltage of the FET Q62, the turn-off time for turning off the capacitor C11, the feedback winding L13, the resistor R13, the diode D145, the transistor Q14, and the capacitor C11 becomes long. Once resonance starts, the FET Q62 can be sufficiently turned on by the electromotive force of the feedback winding L13. Therefore, when the FET Q62 is turned on using the diode D61, the charge of the capacitor C11 through the path of the capacitor C11, the diode D61, the FET Q62, and the capacitor C11. Is discharged so that the voltage across the capacitor C11 becomes approximately 0V.
[0064]
The DC / AC conversion circuit 62 includes an FET (main switching element) Q62 that turns on / off between both ends of the capacitor (DC power supply) C1, and another FET Q62 that turns on / off between both ends of the capacitor (another DC power supply) C2. A resonant capacitor C62 connected in parallel to each of these two FETs Q62, a primary winding interposed on a path where one FET Q62 is turned on / off and on the path where the other FET Q62 is turned on / off It has a line (inductor) L62, and a secondary winding L65 with a center tap that is magnetically coupled to the primary winding L62.
[0065]
The two on control circuits 13 turn on the two FETs Q62 using the electromotive force obtained from the feedback winding L13, and the two off control circuits 14 respectively turn off the off control capacitors C141. The two-stone FET Q62 is controlled to be turned on according to the charging time, and the two-stone FET Q62 is turned off when the on-period elapses.
[0066]
Furthermore, the polarity of one feedback winding L13 is opposite to that of the other feedback winding L13, and the polarity of one feedback winding L14 is opposite to that of the other feedback winding L14.
[0067]
With this configuration, a half-bridge circuit in which two FETs Q62 are alternately turned on / off is obtained. In this half-bridge circuit, the resonance is a so-called partial resonance by the internal diode of each FET Q62. That is, as in the other embodiments described above, resonance starts when the FET Q62 is turned off after being turned on, but when the voltage applied between the drain and source of one FET Q62 turned off becomes equal to or higher than the power supply voltage due to the resonance, Therefore, when the drain-source voltage is equal to or higher than the power supply voltage, resonance is not performed.
[0068]
FIG. 8 is a waveform diagram of each part during the operation of the self-excited resonant inverter circuit. The operation of the self-excited resonant inverter circuit will be described below with reference to FIG.
[0069]
First, when the power is turned on, the primary winding L62 is interposed in the start circuit 11 on the A side, so that the voltage of the capacitor C11 of the start circuit 11 on the B side first reaches the turn-on threshold value of the FET Q62. Thus, the FET Q62 on the B side is turned on first.
[0070]
On the B side, when the FET Q62 is turned on, current flows while increasing in this order on the path of the capacitor C2, the primary winding L62, the FET Q62, and the capacitor C2. The primary winding L62 is reversely excited by this current, and a reverse electromotive force is induced in the feedback winding L14. As a result, a positive voltage is applied to the off-control capacitor C141 from the feedback winding L14 through one (upper in the figure) series circuit, the voltage of the off-control capacitor C141 increases, and the base voltage of the transistor Q14 increases. To do. Thereafter, when the base voltage of the transistor Q14 reaches its turn-on threshold (time t10), the transistor Q14 is turned on and the FET Q62 is turned off.
[0071]
On the other hand, on the A side, even if the voltage of the capacitor C11 of the starting circuit 11 rises behind the starting circuit 11 on the B side and the base voltage of the transistor Q14 reaches its turn-on threshold, the primary winding L62 Due to the reverse excitation, a reverse electromotive force is induced in the feedback winding L13, and the gate voltage of the FET Q62 is lowered. Therefore, the FET Q62 is not turned on but remains off.
[0072]
On the B side, when the FET Q62 is turned off, the excitation energy of the primary winding L62 moves to the resonance capacitor C62 and the drain voltage increases. Thereafter, when the drain voltage becomes equal to or higher than the voltage of the capacitor C2, it is clamped by the internal diode of the A-side FET Q62 (time t11). When such voltage fluctuation occurs, the primary winding L62 is positively excited and a positive electromotive force is induced in the feedback windings L13 and L14. As a result, a positive voltage is generated in the feedback winding L14, and the off-control capacitor C141 begins to discharge through the lower series circuit, so that the base voltage of the transistor Q14 decreases (see “B-side C141 voltage”). . Thereafter, when the base voltage of the transistor Q14 becomes lower than the turn-on threshold value, the transistor Q14 is turned off. On the other hand, the gate voltage of the FET Q62 becomes lower than the turn-on threshold value, so the FET Q62 is kept off.
[0073]
On the other hand, when the FET Q62 on the B side is turned off on the A side, a reverse electromotive force is not induced in the feedback winding L13 and a positive electromotive force is induced, so that the gate voltage of the FET Q62 rises and turns on. The threshold value is reached, and the FET Q62 is turned on (time t12). Thereafter, current flows in this order on the path of the capacitor C1, the FET Q62, the primary winding L62 and the capacitor C1, and the primary winding L62 is positively excited and positive in the feedback windings L13 and L14. An electromotive force is induced. As a result, a positive voltage is applied to the off-control capacitor C141 from the feedback winding L14 through the upper series circuit, the voltage of the off-control capacitor C141 rises, and the base voltage of the transistor Q14 rises (“A side” Of C141 in FIG. Thereafter, when the base voltage of the transistor Q14 reaches its turn-on threshold, the transistor Q14 is turned on and the FET Q62 is turned off (time point t13). Thereafter, resonance starts, the drain voltage rises and is clamped (time t14), the primary winding L62 is excited in reverse, and a reverse electromotive force is induced in the feedback windings L13 and L14. As a result, the off-control capacitor C141 begins to discharge, and the base voltage of the transistor Q14 decreases (see “A-side C141 voltage”). Thereafter, when the base voltage of the transistor Q14 becomes lower than the turn-on threshold value, the transistor Q14 is turned off. On the other hand, the gate voltage of the FET Q62 becomes lower than the turn-on threshold value, so the FET Q62 is kept off.
[0074]
On the other hand, on the B side, when the A side FET Q62 is turned off (time point t13), a positive electromotive force is not induced in the feedback winding L13 and a reverse electromotive force is induced, so that the gate voltage of the FET Q62 increases. The turn-on threshold is reached and the FET Q62 is turned on. Thereafter, the current flows while increasing in this order on the path of the capacitor C2, the primary winding L62, the FET Q62, and the capacitor C2, and the primary winding L62 is positively excited so that the feedback windings L13 and L14 are positive. An electromotive force is induced. As a result, the voltage of the off-control capacitor C141 increases and the base voltage of the transistor Q14 increases. Thereafter, when the base voltage of the transistor Q14 reaches its turn-on threshold, the transistor Q14 is turned on and the FET Q62 is turned off (time point t15).
[0075]
Thereafter, similarly, the pair of FETs Q62 are alternately turned on / off alternately with a dead time so as not to be turned on simultaneously. Thereby, the inverter operation is continued.
[0076]
As described above, according to the sixth embodiment, it is possible to achieve the same effect as that of the first embodiment, and it is possible to configure a half-bridge circuit system.
[0077]
【The invention's effect】
  As is clear from the above, claims 1, 2 and7According to the described invention, it becomes possible to eliminate the need for heat dissipation countermeasures for resistance loss even at high output, and it is possible to easily realize output stabilization control and variable output control as required. Become.
  According to the first aspect of the present invention, adjustment control of the ON period of the main switching element can be performed.
[0078]
According to the invention described in claim 3, it is possible to reduce the size.
[0079]
According to the fourth aspect of the present invention, it is possible to suppress the voltage of the auxiliary switching element from being greatly stepped down in the negative direction.
[0080]
According to the fifth aspect of the present invention, stable off control of the main switching element is possible.
[0082]
  Claim6According to the described invention, automatic adjustment control of the ON period of the main switching element is possible.
[0083]
  Claim8According to the described invention, a push-pull circuit type configuration is possible.
[0084]
  Claim9According to the described invention, a configuration of a half-bridge circuit system is possible.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a self-excited resonant inverter circuit according to a first embodiment of the present invention.
FIG. 2 is a waveform showing the voltage on the FET side of the primary winding, the drain current flowing through the FET, the gate voltage of the FET, the base voltage of the transistor, and the voltage of the off-control capacitor during the operation of the self-excited resonance type inverter circuit; FIG.
FIG. 3 is a schematic configuration diagram showing a self-excited resonant inverter circuit according to a second embodiment of the present invention.
FIG. 4 is a schematic configuration diagram showing a self-excited resonant inverter circuit according to a third embodiment of the present invention.
FIG. 5 is a schematic configuration diagram showing a self-excited resonance type inverter circuit according to a fourth embodiment of the present invention.
FIG. 6 is a schematic configuration diagram showing a self-excited resonance type inverter circuit according to a fifth embodiment of the present invention.
FIG. 7 is a schematic configuration diagram showing a self-excited resonant inverter circuit according to a sixth embodiment of the present invention.
FIG. 8 is a waveform diagram of each part during operation of the self-excited resonance type inverter circuit.
FIG. 9 is a schematic configuration diagram of a conventional self-excited resonance type inverter circuit showing an example of a circuit system of self-excited oscillation.
FIG. 10 is a diagram showing another method using an auxiliary switching element.
[Explanation of symbols]
11 Start-up circuit
12 DC-AC converter circuit
13 ON control circuit
14 OFF control circuit
Q12 FET
Q14 transistor
L12 Primary winding
L13, L14 Feedback winding
C12 Resonant capacitor
C141 Off-control capacitor

Claims (9)

A main switching element that turns on / off between both output terminals of the DC power supply, an inductor that is interposed on a path that the main switching element is turned on / off, and a resonance capacitor that forms a resonance circuit together with the inductor; A DC / AC conversion circuit that converts DC power from the DC power source into high-frequency AC power;
An on-control circuit for turning on the main switching element using an electromotive force obtained from a feedback inductor magnetically coupled to the inductor;
Two diodes connected in reverse parallel, two resistors each constituting a series circuit with the two diodes, one end of the feedback inductor magnetically coupled to the inductor via the two sets of series circuits An off-control capacitor to be connected; a diode having an anode connected to one end of the off-control capacitor; and an auxiliary switching element connected to the cathode of the diode; In response to controlling the ON period from the ON time point to the OFF time point of the main switching element, and the auxiliary switching element turns off the main switching element when the ON period has elapsed ,
A self-excited resonant inverter circuit comprising a power supply for supplying power to the off-control capacitor . The on-control circuit has a first feedback inductor as the feedback inductor for obtaining an electromotive force used to turn on the main switching element,
The self-excited resonant inverter circuit according to claim 1, wherein the off-control circuit includes a second feedback inductor as the feedback inductor connected to the off-control capacitor via the two sets of series circuits.   2. The self-excited resonant inverter circuit according to claim 1, wherein both the on control circuit and the off control circuit share a feedback inductor magnetically coupled with the inductor by the same feedback inductor.   The self-excited resonant inverter circuit according to any one of claims 1 to 3, further comprising a discharge voltage clamping diode having a cathode and an anode connected to one end and the other end of the off-control capacitor, respectively.   The self-voltage according to any one of claims 1 to 4, further comprising a constant voltage circuit that applies a positive voltage of an electromotive force generated by the magnetic coupling to the off-control capacitor through the two sets of series circuits. Excited resonance inverter circuit. Claims before SL power, comprising a detection circuit for performing signal detection for on-period adjustment control of the main switching element, and a control circuit for supplying electric power to the off-control capacitor in accordance with the detection result of the detecting circuit Item 2. A self-excited resonant inverter circuit according to Item 1 . Before SL main switching element is stone, the resonance capacitor is self-excited resonant inverter circuit according to any one of claims 1 to 6 that will be connected in parallel to the inductor. Two sets of the DC / AC converter circuit, the on control circuit and the off control circuit,
The inductor of the DC / AC converter circuit in one of the two sets, the feedback inductor used in the ON control circuit, and the feedback inductor used in the OFF control circuit are respectively the DC / AC converter circuits in the other of the two sets. The polarity of the inductor is opposite to that of the feedback inductor used in the on-control circuit and the feedback inductor used in the off-control circuit ,
Self-excited resonant inverter circuit according to any one of claims 1 to 6, wherein said two sets of each resonance capacitor is connected in parallel to the inductor in the same set. Before having the two Kio emission control circuit and off control circuit,
Before Symbol DC-AC conversion circuit, the main switching element, another main switching element for on / off between both output ends of another of the DC power source to be the DC power supply and connected in series, the main switching element of the two stone resonance capacitor connected in parallel to each, and the upper path and the other of the main switching element of the two stone will turn on / off with one of the main switching element 2 stone is interposed on the path for performing an on / off Having an inductor interposed in the
The two on control circuits turn on the two main switching elements using the electromotive force obtained from the feedback inductor,
The two off-control circuits, respectively, which controls the on period of the main switching element of the two stone, clear the main switching element of the two stone upon elapse of the on period,
Feedback inductor utilized in one of the two on the control circuit, the polarity is reversed with respect to the feedback inductor utilized in the other of the two on-control circuit,
Feedback inductor utilized in one of the two off control circuit, to one of the claims 1-6 polarity Ru reverse der for the feedback inductor utilized in the other of the two off control circuit The self-excited resonant inverter circuit described .

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