JP2011167034A - Resonant type converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a reverse current from flowing to two or more switch elements for rectifying power generated in a secondary winding of a transformer in a resonant type converter having the switch elements and operating in a discontinuous mode. <P>SOLUTION: The resonant type converter 1 includes: a transformer T; switch elements Q1-Q4 formed on the primary side of the transformer T; switch elements Q5, Q6 formed on the secondary side of the transformer T; a primary side controller 111; and a secondary side controller 12. The primary side controller 111 generates a primary side drive signal, and supplies the generated signal to the switch elements Q1-Q4. The secondary side controller 12 detects currents flowing through the switch elements Q5, Q6 to generate a detection signal, obtains logical multiplication between the detection signal and a drive permission signal having a pulsewidth of predetermined time, generates a secondary side drive signal, and supplies the generated signal to the switch elements Q5, Q6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a resonant converter.

  Conventionally, a resonant converter has been used as a switching power supply device (see, for example, Patent Document 1).

[Configuration of Resonant Type Converter 100]
FIG. 13 is a circuit diagram of a resonant converter 100 according to a conventional example. The resonant converter 100 includes a transformer T, a DC power source VIN, switch elements Q1, Q2, Q3, Q4, Q5, and Q6 configured by N-channel MOSFETs, an inductor Lr, capacitors Cr and C1, and a primary side. A control unit 111 and a secondary side control unit 112. The resonant converter 100 operates in the discontinuous mode to supply DC power to the load Load.

  First, the configuration of the primary side of the transformer T will be described. On the primary side of the transformer T, a full bridge circuit is provided by switch elements Q1 to Q4. These switch elements Q1 to Q4 are connected in series with a primary winding T1, an inductor Lr, and a capacitor Cr of the transformer T. Connected to the series circuit. Specifically, the drain of the switch element Q1 and the drain of the switch element Q3 are connected to the positive electrode of the DC power supply VIN, and the source of the switch element Q2 and the switch element Q4 are connected to the negative electrode of the DC power supply VIN. The source is connected. The primary side control unit 111 is connected to each gate of the switch elements Q1 to Q4. The source of the switch element Q1 and the drain of the switch element Q2 are connected to each other, and a primary winding T1 of the transformer T is connected to these connection points via an inductor Lr and a capacitor Cr that form a resonance circuit. Are connected at one end. The source of the switch element Q3 and the drain of the switch element Q4 are connected to each other, and the other end of the primary winding T1 of the transformer T is connected to these connection points.

  Next, the configuration of the secondary side of the transformer T will be described. The drain of the switch element Q6 is connected to one end of the first secondary winding T2 of the transformer T. The other end of the first secondary winding T2 of the transformer T is connected to one electrode of the capacitor C1, one end of the load Load, and one end of the second secondary winding T3 of the transformer T. . The other end of the second secondary winding T3 of the transformer T is connected to the drain of the switch element Q5. The other electrode of the capacitor C1 and the other end of the load Load are connected to the source of the switch element Q5 and the source of the switch element Q6. Secondary control unit 112 is connected to the gates of switch elements Q5 and Q6.

[Operation of Resonant Type Converter 100]
The resonant converter 100 having the above configuration controls the switch elements Q1 to Q4 by the primary side control unit 111. Specifically, the drive signal _SIG Q1 corresponding to the respective switching elements Q1 to _Q4, SIG _Q2, the SIG Q3, _{SIG Q4} is outputted from the primary-side control unit 111, each of these drive signals _SIG Q1 to Sig _Q4 It supplies to each gate of switch element Q1-Q4. A period in which the switch elements Q1 and Q4 are on and the switch elements Q2 and Q3 are off and a period in which the switch elements Q1 and Q4 are off and the switch elements Q2 and Q3 are on are dead. Alternating time is provided. According to this, the resonance current by the resonance circuit composed of the inductor Lr and the capacitor Cr flows from one end of the primary winding T1 of the transformer T to the other end, or from the other end of the primary winding T1 of the transformer T. Or flow to one end. When a current flows through the primary winding T1 of the transformer T, an electromotive force is generated in the first secondary winding T2 and the second secondary winding T3 of the transformer T.

The resonant converter 100 controls the switch elements Q5 and Q6 by the secondary side control unit 112. Specifically, the secondary side control unit 112 first detects the drain currents of the switch elements Q5 and Q6. Next, based on the detection result, drive signals SIG _Q5 and SIG _Q6 to be supplied to the respective gates of the switch elements Q5 and _Q6 are generated, and these drive signals SIG _Q5 and SIG _Q6 are respectively connected to the switch elements Q5 and Q6. Supply to the gate. According to this, the electromotive force generated in the first secondary winding T2 and the second secondary winding T3 of the transformer T is synchronously rectified by the switch elements Q5 and Q6.

  The electromotive force synchronously rectified by the switch elements Q5 and Q6 is smoothed by the capacitor C1, and then supplied to one end of the load Load.

  The resonant converter 100 has a characteristic that the voltage supplied to one end of the load Load, that is, the output voltage Vout decreases as the switching frequency of the switching elements Q1 to Q4 increases. Therefore, the resonant converter 100 controls the output voltage Vout by controlling the switching frequency of the switch elements Q1 to Q4.

JP 2006-271099 A

FIG. 14 is an ideal timing chart of the resonant converter 100 operating in the discontinuous mode. VSIG _Q1 , VSIG _Q2 , VSIG _Q3 , VSIG _Q4 , VSIG _Q5 , and VSIG _Q6 indicate the voltages of the drive signals SIG _{Q1 to} SIG _Q6 of the switch elements _{Q1 to Q6} , respectively. Each of VGS _Q1 , VGS _Q2 , VGS _Q3 , VGS _Q4 , VGS _Q5 , and VGS _Q6 indicates a gate-source voltage of each of the switch elements Q1 to _Q6 . ID _Q1 , ID _Q2 , ID _Q3 , ID _Q4 , ID _Q5 , and ID _Q6 indicate the drain currents of the switch elements Q1 to _Q6 , respectively. Ir represents a resonance current flowing from one end of the primary winding T1 of the transformer T to the other end.

When the gate-source voltage VGS _Q1 of the switch element Q1 is VH, the switch element Q1 is turned on. When the gate-source voltage VGS _Q1 of the switch element Q1 is VL, the switch element Q1 is It shall be in the off state. Also, each of the switch elements Q2 to Q6 is assumed to be turned on or turned off in accordance with the gate-source voltage, similarly to the switch element Q1 described above.

The ideal secondary-side control unit 112 is configured such that the gate-source voltage of the switch element Q5 is only in a period in which the drain current ID _Q5 of the switch element Q5 is greater than “0”, such as the period from time t2 to time t3. VGS _{Q5 is set} to VH, and switch element Q5 is turned on. Further, for example, only during a period when the drain current ID _Q6 of the switch element Q6 is larger than “0” as in a period from time t5 to t6, the gate-source voltage VGS _Q6 of the switch element _{Q6 is set} to VH, and the switch element Q6 is turned on. That is, the ideal secondary-side control unit 112 turns on the switch element Q5 during a period when the current flows through the switch element Q5, and turns on the switch element Q6 during a period when the current flows through the switch element Q6. To do.

  On the other hand, FIG. 15 is an actual timing chart of the resonant converter 100 operating in the discontinuous mode.

In the actual secondary side control unit 112, there is a delay in detecting the drain currents ID _Q5 and ID _Q6 of the switch elements Q5 and Q6. Therefore, the switch elements Q5 and Q6 generated based on this detection result. The respective drive signals SIG _Q5 and SIG _Q6 are also delayed due to the above-described delay. For this reason, the timing of turning on the switch elements Q5 and Q6 and the timing of turning off are delayed.

According to this, when the drain current ID _Q5 of the switch element _Q5 becomes “0”, for example, during a period from time t24 to t25, the switch element Q5 remains in the on state. There is. In this case, in the period from when the drain current ID _Q5 of the switch element Q5 is turned to "0" until the switch element Q5 is turned off, it becomes smaller than the drain current ID _Q5 of the switch element Q5 is "0", the switch elements A reverse current will flow through Q5.

Further, for example, during the period from time t29 to t30, the switch element Q6 may remain in the on state even though the drain current ID _Q6 of the switch element Q6 has become “0”. In this case, in the period from when the drain current ID _Q6 of the switching element Q6 is turned to "0" until the switch element Q6 is turned off, it becomes smaller than the drain current ID _Q6 of the switching element Q6 is "0", the switch elements A reverse current will flow through Q6.

  As described above, when a backflow current flows through the switch element Q5 and the switch element Q6, secondary energy due to the backflow current is regenerated to the primary side of the transformer T, and loss increases.

  In view of the above-described problems, the present invention includes two or more switch elements that rectify power generated in the secondary winding of a transformer, and in a resonant converter that operates in a discontinuous mode, a reverse current flows through these switch elements. The purpose is to prevent it.

The present invention proposes the following items in order to solve the above-described problems.
(1) The present invention relates to a transformer, an inductor and a capacitor connected in series to the primary winding of the transformer, and a series circuit in which the primary winding of the transformer, the inductor, and the capacitor are connected in series. A resonant converter comprising two or more primary-side switch elements connected to each other and two or more secondary-side switch elements that rectify power generated in a secondary winding of the transformer, Primary side control means for supplying a primary side drive signal to each control terminal of the primary side switch element, and a secondary side drive signal to each control terminal of the two or more secondary side switch elements Secondary side control means for detecting current flowing in each of the two or more secondary side switch elements, generating a detection signal based on the detection result, and A drive permission signal having a pulse width of a predetermined time with reference to a start edge of the primary side drive signal is generated, a logical product of the detection signal and the drive permission signal is obtained, and the secondary side drive signal A resonant converter characterized by the above is proposed.

  According to the present invention, the transformer, the inductor and the capacitor connected in series to the primary winding of the transformer, and two or more connected to the series circuit in which the primary winding, the inductor and the capacitor of the transformer are connected in series The primary side control means and the secondary side control means are provided in a resonant converter comprising a primary side switch element and two or more secondary side switch elements that rectify power generated in the secondary winding of the transformer. Provided. Then, the primary side drive signal is supplied to the control terminals of the two or more primary side switch elements by the primary side control means. The secondary control means detects the current flowing in each of the two or more secondary switch elements, generates a detection signal based on the detection result, and uses the start edge of the primary drive signal as a reference in advance. A drive permission signal having a pulse width of a predetermined time is generated, and a logical product of the detection signal and the drive permission signal is obtained to obtain a secondary side drive signal to each control terminal of two or more secondary side switch elements. It was decided to supply.

  For this reason, in the resonant converter operating in the discontinuous mode, the end edge of the drive permission signal is provided before the timing at which no current flows to the secondary side switch element by adjusting the pulse width of the drive permission signal. Can do. The end edge of the drive permission signal is a falling edge when the secondary side switch element is positive logic, and is a rising edge when the secondary side switch element is negative logic.

  According to this, in the resonance type converter operating in the discontinuous mode, each of the two or more secondary side switch elements is provided at the end edge of the secondary side drive signal obtained by the logical product of the detection signal and the drive permission signal. Even if a delay occurs in detecting the current flowing through the secondary side control means, a delay due to this delay does not occur. The end edge of the secondary drive signal is a falling edge when the secondary side switch element is positive logic, and a rising edge when the secondary side switch element is negative logic. is there.

  For this reason, even if a delay occurs when the current flowing through each of the two or more secondary-side switch elements is detected by the secondary-side control means, it is possible to prevent the timing of turning off these secondary-side switch elements from being delayed. In two or more secondary-side switch elements, it is possible to prevent the switch from being kept in the on state even when the current flowing through the switch element becomes “0”. Therefore, it is possible to prevent a backflow current from flowing through these secondary side switch elements.

  (2) The present invention proposes a resonant converter characterized in that, for the resonant converter of (1), the predetermined time is equal to half the resonant period of the resonant circuit having the inductor and the capacitor. is doing.

  Here, in the resonant converter operating in the discontinuous mode, the time during which the current flows through the secondary side switching element, and the half of the resonant period of the resonant circuit having the inductor and the capacitor connected in series to the primary winding of the transformer, Are approximately equal.

  Therefore, according to the present invention, the pulse width of the drive permission signal is made equal to half the resonance period of the resonance circuit having the inductor and the capacitor. For this reason, in the resonant converter that operates in the discontinuous mode, the timing of the end edge of the drive permission signal is substantially equal to the timing at which no current flows through the secondary side switch element. According to this, an effect similar to the effect mentioned above can be produced.

  (3) The present invention relates to the resonant converter according to (1), wherein the predetermined time is determined by changing the two or more secondary side switching elements from a half of a resonance period of a resonant circuit having the inductor and the capacitor. A resonant converter characterized by being equal to a time obtained by subtracting a delay time generated when driving is proposed.

  According to the present invention, the pulse width of the drive permission signal is set to a time obtained by subtracting the delay time generated when driving two or more secondary-side switch elements from half the resonance period of the resonance circuit having the inductor and the capacitor. We decided to make them equal. According to this, an effect similar to the effect mentioned above can be produced.

  In addition, the phase of the end edge of the drive permission signal advances by the amount of delay time that occurs when two or more secondary-side switch elements are driven. For this reason, the phase of the end edge of the secondary side drive signal obtained by calculating the logical product of the detection signal and the drive permission signal with advanced phase advances by the above-described delay time.

  According to this, even when a delay occurs when driving two or more secondary side switch elements, it is possible to prevent the timing of turning off these secondary side switch elements from being delayed. In FIG. 5, it is possible to prevent the current flowing through itself from being kept on even though the current is “0”. Therefore, it is possible to prevent a backflow current from flowing through these secondary side switch elements.

  (4) The present invention relates to a transformer, an inductor and a capacitor connected in series to the primary winding of the transformer, and a series circuit in which the primary winding of the transformer, the inductor, and the capacitor are connected in series. A resonant converter comprising two or more primary-side switch elements connected to each other and two or more secondary-side switch elements that rectify power generated in a secondary winding of the transformer, A primary side control means for outputting a primary side drive signal to be supplied to each control terminal of the primary side switch element, and a primary side drive signal output from the primary side control means are determined in advance. Delay means for delaying by one time and supplying the control terminals to the control terminals of the two or more primary side switch elements and secondary side drive signals to the control terminals of the two or more secondary side switch elements Secondary side control means for supplying, and the secondary side control means detects a current flowing through each of the two or more secondary side switch elements, generates a detection signal based on the detection result, Generating a drive permission signal having a pulse width of a second time determined in advance with reference to a start edge of the primary side drive signal before being input to the delay means; and the detection signal, the drive permission signal, A resonant converter is proposed in which the logical product is obtained and used as the secondary drive signal.

  According to the present invention, the transformer, the inductor and the capacitor connected in series to the primary winding of the transformer, and two or more connected to the series circuit in which the primary winding, the inductor and the capacitor of the transformer are connected in series A resonance type converter including a primary side switching element, and two or more secondary side switching elements for rectifying the electric power generated in the secondary winding of the transformer. Side control means were provided. The primary side control means outputs primary side drive signals to be supplied to the control terminals of the two or more primary side switch elements, and the delay means outputs the primary side output from the primary side control means. The drive signal is delayed by a predetermined first time and supplied to each control terminal of two or more primary side switch elements. Further, the secondary side control means detects the current flowing through each of the two or more secondary side switch elements, generates a detection signal based on the detection result, and also drives the primary side before being input to the delay means. A drive permission signal having a pulse width of a second time determined in advance with reference to the start edge of the signal is generated, and a logical product of the detection signal and the drive permission signal is obtained to obtain a secondary side drive signal. Suppose that it supplies to each control terminal of a secondary side switch element.

  For this reason, in the resonant converter operating in the discontinuous mode, the end edge of the drive permission signal is provided before the timing at which no current flows to the secondary side switch element by adjusting the pulse width of the drive permission signal. Can do. For this reason, the effect similar to the effect mentioned above can be produced.

  Further, since the primary side drive signal delayed by a predetermined first time by the delay means is supplied to the two or more primary side switch elements, the operation of these primary side switch elements is the delay means. Compared to the case where no is provided, it is delayed by the first time. Since the current flowing through the two or more secondary side switch elements changes according to the operation of the primary side switch element, the current flowing through these secondary side switch elements is also delayed by the first time. On the other hand, since the primary side drive signal used by the secondary side control means is the primary side drive signal before being input to the delay means, it is not delayed by the first time described above.

  According to the above, the phase of the primary side drive signal used by the secondary side control means is relatively advanced by the first time compared with the phase of the current flowing through the secondary side switch element. . For this reason, the phase of the end edge of the secondary drive signal obtained by calculating the logical product of the detection signal and the drive permission signal generated based on the primary drive signal with the advanced phase is the first It will be relatively advanced by the amount of time.

  According to this, even when a delay occurs when driving two or more secondary-side switch elements, the timing at which these secondary-side switch elements are turned off by setting the first time to be equal to or longer than the delay time. Therefore, it is possible to prevent the two or more secondary-side switching elements from remaining in the ON state even when the current flowing through them becomes “0”. Therefore, it is possible to prevent a backflow current from flowing through these secondary side switch elements.

  (5) In the resonance type converter according to (4), the predetermined second time is equal to half the resonance period of the resonance circuit having the inductor and the capacitor. A converter is proposed.

  Here, in the resonant converter operating in the discontinuous mode, the time during which the current flows through the secondary side switching element, and the half of the resonant period of the resonant circuit having the inductor and the capacitor connected in series to the primary winding of the transformer, Are approximately equal.

  Therefore, according to the present invention, the pulse width of the drive permission signal is made equal to half the resonance period of the resonance circuit having the inductor and the capacitor. For this reason, in the resonant converter operating in the discontinuous mode, the timing of the end edge of the drive permission signal is advanced by the first time compared to the timing at which no current flows through the secondary side switching element. According to this, an effect similar to the effect mentioned above can be produced.

  (6) In the resonant converter according to (4), the predetermined second time is from the half of the resonance period of the resonant circuit having the inductor and the capacitor to the two or more secondary sides. A resonant converter is proposed which is characterized by being equal to the time obtained by subtracting the delay time generated when the switch element is driven.

  According to the present invention, the pulse width of the drive permission signal is set to a time obtained by subtracting the delay time generated when driving two or more secondary-side switch elements from half the resonance period of the resonance circuit having the inductor and the capacitor. We decided to make them equal. According to this, an effect similar to the effect mentioned above can be produced.

  In addition, the phase of the end edge of the drive permission signal advances by the amount of delay time that occurs when two or more secondary-side switch elements are driven. For this reason, the phase of the end edge of the secondary side drive signal obtained by calculating the logical product of the detection signal and the drive permission signal with advanced phase advances by the above-described delay time.

  According to this, even when a delay occurs when driving two or more secondary side switch elements, it is possible to prevent the timing of turning off these secondary side switch elements from being delayed. In FIG. 5, it is possible to prevent the current flowing through itself from being kept on even though the current is “0”. Therefore, it is possible to prevent a backflow current from flowing through these secondary side switch elements.

  (7) In the resonance converter according to any one of (4) to (6), the predetermined first time is generated when the two or more secondary-side switch elements are driven. A resonant converter characterized by being equal to the delay time is proposed.

  According to the present invention, the time for delaying the primary side drive signal output from the primary side control means by the delay means is made equal to the delay time generated when driving two or more secondary side switch elements. did. According to this, an effect similar to the effect mentioned above can be produced.

  (8) The present invention proposes a resonant converter characterized in that the two or more primary-side switching elements constitute a full bridge circuit for the resonant converter according to any one of (1) to (7). is doing.

  According to the present invention, a full bridge circuit is constituted by two or more primary side switching elements. For this reason, even if it is a resonance type converter in which the full bridge circuit was provided in the primary side of a transformer, the same effect as the effect mentioned above can be produced.

  According to the present invention, in a resonant converter that includes two or more switch elements that rectify power generated in the secondary winding of a transformer and operates in a discontinuous mode, a reverse current flows through these switch elements. Can be prevented.

1 is a circuit diagram of a resonant converter according to a first embodiment of the present invention. It is a figure for demonstrating operation | movement of the primary side control part with which the said resonance type converter is provided. It is a figure for demonstrating operation | movement of the said primary side control part. 3 is an actual timing chart of the resonant converter. It is a circuit diagram of the resonance type converter concerning a 2nd embodiment of the present invention. It is a figure for demonstrating operation | movement of the primary side control part with which the said resonance type converter is provided. It is a figure for demonstrating operation | movement of the said primary side control part. 3 is an actual timing chart of the resonant converter. It is a circuit diagram of the resonance type converter concerning a 3rd embodiment of the present invention. It is a figure for demonstrating operation | movement of the primary side control part with which the said resonance type converter is provided. It is a figure for demonstrating operation | movement of the said primary side control part. 3 is an actual timing chart of the resonant converter. It is a circuit diagram of the resonance type converter which concerns on a prior art example. It is an ideal timing chart of the resonant converter. 3 is an actual timing chart of the resonant converter.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the constituent elements in the following embodiments can be appropriately replaced with existing constituent elements, and various variations including combinations with other existing constituent elements are possible. Accordingly, the description of the following embodiments does not limit the contents of the invention described in the claims.

<First Embodiment>
[Configuration of Resonant Converter 1]
FIG. 1 is a circuit diagram of a resonant converter 1 according to the first embodiment of the present invention. The resonant converter 1 is different from the resonant converter 100 according to the conventional example shown in FIG. 13 in that a secondary side control unit 12 as a secondary side control unit is provided instead of the secondary side control unit 112. . In the resonant converter 1, the same components as those of the resonant converter 100 are denoted by the same reference numerals, and the description thereof is omitted.

[Operation of Resonant Converter 1]
Resonant converter 1 operates in a discontinuous mode, similarly to resonant converter 100 according to the conventional example shown in FIG. 13, and controls the switching frequency of switching elements Q1 to Q4 as primary side switching elements. The output voltage Vout is controlled. However, in order to cope with a later-described detection delay time Td1 that cannot be handled by the resonant converter 100, a switch element Q5 as a secondary side switch element based on the drain currents ID _Q5 and ID _Q6 of the switch elements Q5 and Q6, The timing of the falling edges of the drive signals SIG _Q5 and SIG _Q6 of _Q6 is different from that of the resonant converter 100. Control of the switch elements Q5 and Q6 by the secondary side control unit 12 will be described below with reference to FIGS.

  2 and 3 indicate the voltage of a drive permission signal SIG1 described later, and VSIG2 illustrated in FIG. 4 described later indicates the voltage of a drive permission signal SIG2 described later.

  As shown in FIG. 2, the secondary control unit 12 obtains a logical product of the secondary resonance current detection signal as the detection signal and the drive permission signal, and drives the secondary side as the secondary drive signal. Generate a signal.

Specifically, when the drive signal SIG _Q5 of the switch element Q5 is generated as the secondary side drive signal, first, the drain current ID _Q5 of the switch element _Q5 is detected, and the drain current ID _Q5 is larger than “0”. Only during the period, the secondary resonance current detection signal XID _Q5 which is ideally VH is generated. However, in reality, a delay occurs when detecting the drain current ID _Q5 of the switch element Q5 in the same manner as the secondary side control unit 112 shown in FIG. Here, the delay time that occurs when the secondary current control unit 12 detects the drain current ID _Q5 of the switch element Q5 is referred to as a detection delay time Td1. Then, as shown in FIG. 3, the secondary resonance current detection signal XID _Q5 becomes VH at the timing when the detection delay time Td1 has elapsed after the drain current ID _Q5 of the switch element Q5 becomes larger than “0”. Further, since the drain current _{ID Q5} of the switch element Q5 is turned to "0" at the timing of detection delay time Td1 has elapsed, the secondary resonance current detection signal _{XID Q5} becomes VL.

Further, the drive signals SIG _Q1 and SIG _Q4 of the switch elements Q1 and Q4 as the primary side drive signals provided in pairs with the switch element Q5 become VH at the timing when the drive signals SIG _Q1 and SIG _Q4 become VH (hereinafter referred to as “first timing”). A drive permission signal SIG1 that generates VL at the timing when half the resonance period Tr of the resonance circuit composed of the inductor Lr and the capacitor Cr has elapsed from the first timing is generated.

Next, a logical product of the secondary resonance current detection signal XID _Q5 and the drive permission signal SIG1 is obtained, and a drive signal SIG _Q5 for the switch element _Q5 is generated. According to this, when both the voltage of the secondary resonance current detection signal XID _Q5 and the voltage VSIG1 of the drive permission signal SIG1 are VH, the voltage VSIG _Q5 of the drive signal SIG _Q5 becomes VH. On the other hand, when at least one of the voltage of the secondary resonance current detection signal XID _Q5 and the voltage VSIG1 of the drive permission signal SIG1 is VL, the voltage VSIG _Q5 of the drive signal SIG _Q5 becomes VL. The drive signal SIG _Q5 is supplied from the secondary side control unit 12 to the gate of the switch element Q5.

When the drive signal SIG _Q6 of the switch element Q6 is generated as the secondary drive signal, first, the drain current ID _Q6 of the switch element _Q6 is detected, and only when the drain current ID _Q6 is greater than “0”. The secondary resonance current detection signal XID _Q6 which is ideally VH is generated. However, in actuality, as in the case of the secondary side control unit 112 shown in FIG. 13, a delay occurs when the drain current ID _Q6 of the switch element _Q6 is detected. Here, the delay time that occurs when the secondary current control unit 12 detects the drain current ID _Q6 of the switch element Q6 is referred to as a detection delay time Td1. Then, as shown in FIG. 3, the secondary resonance current detection signal XID _Q6 becomes VH at the timing when the detection delay time Td1 has elapsed since the drain current ID _Q6 of the switching element Q6 becomes larger than “0”. Further, since the drain current _{ID Q6} of the switching element Q6 is turned to "0" at the timing of detection delay time Td1 has elapsed, the secondary resonance current detection signal _{XID Q6} becomes VL.

Further, the drive signals SIG _Q2 and SIG _Q3 of the switch elements Q2 and Q3 as the primary side drive signals provided in pairs with the switch element Q6 become VH at the timing when the drive signals SIG _Q2 and SIG _Q3 become VH (hereinafter referred to as “second timing”). A drive permission signal SIG <b> 2 is generated that becomes VL at the timing when half the resonance period Tr described above has elapsed from the second timing.

Next, a logical product of the secondary resonance current detection signal XID _Q6 and the drive permission signal SIG2 is obtained to generate a drive signal SIG _Q6 for the switch element Q6. According to this, when both the voltage of the secondary resonance current detection signal XID _Q6 and the voltage VSIG2 of the drive permission signal SIG2 are VH, the voltage VSIG _Q6 of the drive signal SIG _Q6 becomes VH. On the other hand, when at least one of the voltage of the secondary resonance current detection signal XID _Q6 and the voltage VSIG2 of the drive permission signal SIG2 is VL, the voltage VSIG _Q6 of the drive signal SIG _Q6 becomes VL. The drive signal SIG _Q6 is supplied from the secondary side control unit 12 to the gate of the switch element Q6.

  FIG. 4 is an actual timing chart of the resonant converter 1 operating in the discontinuous mode.

As shown in FIG. 4, the resonant converter 1, the period drain current _{ID Q5} of the switch element Q5 is "0", the switching element Q5 gate - source voltage _{VGS Q5} is VL, and the drain of the switching element Q6 During the period when the current ID _Q6 is “0”, the gate-source voltage VGS _Q6 of the switch element Q6 becomes VL. Therefore, the switch element Q5 is turned on only during a period when current flows through the switch element Q5, and the switch element Q6 is turned on only during a period when current flows through the switch element Q6.

  According to the above resonant converter 1, the following effects can be obtained.

Even when there is a delay in detecting the drain currents ID _Q5 and ID _Q6 of the switch elements Q5 and Q6, the switch element Q5 is turned on only during the period in which the current flows through the switch element Q5. The switch element Q6 is turned on only during the period when the current flows through Q6. For this reason, it is possible to prevent a backflow current from flowing through the switch elements Q5 and Q6.

Second Embodiment
[Configuration of Resonant Type Converter 1A]
FIG. 5 is a circuit diagram of a resonant converter 1A according to the second embodiment of the present invention. The resonant converter 1A differs from the resonant converter 1 according to the first embodiment of the present invention shown in FIG. 1 in that a secondary side control unit 12A is provided instead of the secondary side control unit 12. In the resonant converter 1A, the same components as those of the resonant converter 1 are denoted by the same reference numerals, and the description thereof is omitted.

[Operation of Resonant Type Converter 1A]
The resonant converter 1A operates in a discontinuous mode and controls the switching frequency of the switch elements Q1 to Q4 in the same manner as the resonant converter 1 according to the first embodiment of the present invention shown in FIG. The voltage Vout is controlled. However, in order to cope with a later-described delay time Td2 that cannot be handled by the resonant converter 1, the drive signals SIG _{Q5 of the} switching elements Q5 and _Q6 with reference to the drain currents ID _Q5 and ID _Q6 of the switching elements Q5 and Q6, respectively. The timing of the falling edge of SIG _Q6 is different from that of resonant converter 1. Control of the switch elements Q5 and Q6 by the secondary side control unit 12A will be described below with reference to FIGS.

  As shown in FIG. 6, similarly to the secondary side control unit 12, the secondary side control unit 12A obtains a logical product of the secondary resonance current detection signal and the drive permission signal, and drives the secondary side drive signal. Is generated. However, the drive permission signal in the secondary side control unit 12 and the drive permission signal in the secondary side control unit 12A are different in the following points.

Specifically, the drive permission signals in the secondary side control unit 12 are the drive permission signals SIG1 and SIG2. Drive permission signal SIG1, the switch element Q1, Q4 driving signal _SIG Q1, _{SIG Q4} becomes VH above first timing VH next of, half the time of the above-described resonance period Tr has elapsed from the first timing described above It is a signal that becomes VL at the timing. The drive permission signal SIG2, the drive signal _SIG Q2 of the switching elements Q2, Q3, VH becomes the second timing described above _{that SIG Q3} becomes VH, the time half of the above-described resonance period Tr from the second timing described above This signal becomes VL at the elapsed timing.

On the other hand, the drive permission signal in the secondary side control unit 12A is the drive permission signals SIG3 and SIG4. Drive permission signal SIG3, the switch element Q1, Q4 driving signal _SIG Q1, _{SIG Q4} becomes VH timing (hereinafter, "third timing" hereinafter) in the VH, and the later from half above the resonance period Tr Time This is a signal that becomes VL at the timing when the time obtained by subtracting the delay time Td2 has elapsed from the third timing. Drive permission signal SIG4, the switch element Q2, Q3 drive signal _SIG Q2, _{timing SIG Q3} becomes VH (hereinafter, "fourth timing" hereinafter) in the VH, and the later from half above the resonance period Tr Time This signal becomes VL at the timing when the time obtained by subtracting the delay time Td2 has elapsed from the fourth timing.

  According to the above, the timing of the falling edge of the drive permission signal in the secondary side control unit 12A is earlier than the timing of the falling edge of the drive permission signal in the secondary side control unit 12 by a later-described delay time Td2. Become.

The above-described delay time Td2 is a delay time caused by the delay factor 121 shown in FIG. 5, and the gate-source voltage VGS _{Q5 of the} switch element _Q5 and the gate-source voltage VGS _{Q6 of the} switch element _Q6. What happens when you change The delay factor 121 is, for example, a gate delay or a wiring delay in the switch elements Q5 and Q6. Further, as shown in FIG. 7, for the switch element Q5, the drive signal before the delay time caused by the delay factor 121 is referred to as a drive signal SIG _Q5, and the drive signal after the delay time caused by the delay factor 121 is This is indicated as a delayed drive signal DSIG _Q5 . For switch element Q6, the drive signal before the delay time caused by delay factor 121 is referred to as drive signal SIG _Q6, and the drive signal after the delay time caused by delay factor 121 is referred to as post-delay drive signal DSIG. It shall be indicated as _Q6 .

  FIG. 8 is an actual timing chart of the resonant converter 1A operating in the discontinuous mode.

As shown in FIG. 8, the resonant converter 1A, a period drain current _{ID Q5} of the switch element Q5 is "0", the switching element Q5 gate - source voltage _{VGS Q5} is VL, and the drain of the switching element Q6 During the period when the current ID _Q6 is “0”, the gate-source voltage VGS _Q6 of the switch element Q6 becomes VL. Therefore, the switch element Q5 is turned on only during a period when current flows through the switch element Q5, and the switch element Q6 is turned on only during a period when current flows through the switch element Q6.

  According to the above resonant converter 1A, the following effects can be obtained.

Even when a delay occurs when detecting the drain current ID _Q5 of the switch element Q5 or driving the switch element Q5 by changing the gate-source voltage VGS _Q5 of the switch element Q5, the switch element Q5 The switch element Q5 is turned on only during a current flow period, and the switch element Q6 is turned on only during a current flow period through the switch element Q6. For this reason, it is possible to prevent a backflow current from flowing through the switch elements Q5 and Q6.

<Third Embodiment>
[Configuration of Resonant Type Converter 1B]
FIG. 9 is a circuit diagram of a resonant converter 1B according to the third embodiment of the present invention. The resonant converter 1B is different from the resonant converter 1 according to the first embodiment of the present invention shown in FIG. 1 in that it includes a delay unit 13 as a delay unit, and a secondary side instead of the secondary side control unit 12. The difference is that the side control unit 12B is provided. In the resonant converter 1B, the same constituent elements as those of the resonant converter 1 are denoted by the same reference numerals, and the description thereof is omitted.

The delay unit 13 is provided between the primary side control unit 111 and the gates of the switch elements Q1 to Q4. The delay unit 13 delays each of the drive signals SIG _{Q1 to} SIG _Q4 output from the primary side control unit 111 by the above-described delay time Td2, and then drives the delayed drive signals DSIG _Q1 , DSIG _Q2 , DSIG _Q3 , DSIG _Q4 is supplied to each gate of the switch elements Q1 to Q4.

[Operation of Resonant Type Converter 1B]
Similar to the resonant converter 1 according to the first embodiment of the present invention shown in FIG. 1, the resonant converter 1B operates in a discontinuous mode and controls the switching frequency of the switch elements Q1 to Q4 to output the resonant converter 1B. The voltage Vout is controlled. However, like the resonant converter 1A according to the second embodiment of the present invention shown in FIG. 5, the drain current ID _Q5 of the switch elements Q5 and Q6 is used to cope with the delay time Td2 that cannot be handled by the resonant converter 1. The timing of the falling edges of the drive signals SIG _Q5 and SIG _Q6 of the switch elements Q5 and _Q6 with respect to ID _Q6 is different from that of the resonant converter 1. Control of the switch elements Q5 and Q6 by the secondary side control unit 12B will be described below with reference to FIGS.

  As shown in FIG. 10, the secondary side control unit 12B obtains the logical product of the secondary resonance current detection signal and the primary side drive signal in the same manner as the secondary side control unit 12. Drive signal is generated. Here, the above-described delay unit 13 is provided in the resonant converter 1B, and the primary side drive signal input to the secondary side control unit 12B is a signal before being input to the delay unit 13. . For this reason, the drive permission signal in the secondary side control part 12 and the drive permission signal in the secondary side control part 12B differ in the following points.

  Specifically, the drive permission signal in the secondary side control unit 12 is the drive permission signals SIG1 and SIG2 as described above.

On the other hand, the drive permission signal in the secondary side control unit 12B is the drive permission signals SIG5 and SIG6. Drive permission signal SIG5, the drive signal _SIG Q1, _{SIG Q4} becomes VH timing (hereinafter, "fifth timing" hereinafter) of the switch element Q1, Q4 is before the signal input to the delay unit 13 in VH, and the This is a signal that becomes VL at a timing when half of the resonance period Tr described above has elapsed from the fifth timing. Drive permission signal SIG6, the drive signal _SIG Q2 of the switching elements Q2, Q3 is a signal before being input to the delay unit 13, the timing _{of SIG Q3} becomes VH (hereinafter "sixth timing" hereinafter) VH becomes in, It is a signal that becomes VL at the timing when half the resonance period Tr described above has elapsed from the sixth timing.

On the other hand, the secondary resonance current detection signal input to the secondary side control unit 12B is a signal that changes according to the signal output from the delay unit 13. Specifically, the switching element Q1 to Q4, for that delaying the drive signal _SIG Q1 to Sig _Q4 delay unit 13 is supplied, the operation of the switch elements Q1 to Q4, the delay unit 13 is provided Compared to the case where it is not, it is delayed by the delay time Td2. Since the drain currents ID _Q5 and ID _Q6 of the switch elements _Q5 and _Q6 change according to the operation of the switch elements Q1 to Q4, the drain currents ID _Q5 and ID _Q6 are also delayed by the delay time Td2.

From the above, when the phase of the drain current ID _Q5 of the switch element Q5 is used as a reference, the phases of the drive signals SIG _Q1 and SIG _Q4 input to the secondary control unit 12B are the drive input to the secondary control unit 12. Compared with the phases of the signals SIG _Q1 and SIG _Q4, the phase advances relatively by the delay time Td2. When the phase of the drain current ID _Q6 of the switch element Q6 is used as a reference, the phases of the drive signals SIG _Q2 and SIG _Q3 input to the secondary control unit 12B are the drive signals input to the secondary control unit 12. Compared to the phases of SIG _Q2 and SIG _Q3, the phase is relatively advanced by the delay time Td2.

  FIG. 12 is an actual timing chart of the resonant converter 1B operating in the discontinuous mode.

As shown in FIG. 12, in the resonant converter 1B, the drive signals SIG _Q1 and VSIG _Q4 of the switch elements Q1 and Q4 change at the timing when the voltages VSIG _Q1 and VSIG _{Q4 of} the SIG _Q4 change from VH to VL. voltage VSIG _Q5 of _Q5 is changed to VL from VH. Then, at the timing when the delay time Td2 has elapsed since the voltage VSIG _Q5 changed from VH to VL, the voltage VDSIG _Q5 of the delayed drive signal DSIG _Q5 of the switch element Q5 changes from VH to VL. The gate-source voltage VGS _{Q5 of the} switch element Q5 to which the DSIG _Q5 is supplied to the gate also changes from VH to VL. For this reason, the switch element Q5 is turned off at a timing before the current starts to flow through the switch element Q6.

Also, the resonant converter 1B, the drive signal _SIG Q2 of the switching elements Q2, Q3, a voltage _VSIG Q2 of _{SIG Q3,} at the timing when VSIG _Q3 changes to VL from VH, the voltage VSIG _Q6 of the drive signal _{SIG Q6} of the switching element Q6 Changes from VH to VL. Then, at the timing when the delay time Td2 has elapsed since the voltage VSIG _Q6 changed from VH to VL, the voltage VDSIG _Q6 of the delayed drive signal DSIG _Q6 of the switch element Q6 changes from VH to VL. The gate-source voltage VGS _{Q6 of the} switch element Q6 to which the DSIG _Q6 is supplied to the gate also changes from VH to VL. For this reason, the switch element Q6 is turned off at a timing before the current starts to flow through the switch element Q5.

  According to the above-described resonance type converter 1B, the same effect as that obtained by the resonance type converter 1A described above can be obtained.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made without departing from the gist of the present invention.

  For example, in each of the embodiments described above, the full bridge circuit is configured on the primary side of the transformer T by the switch elements Q1 to Q4. However, the present invention is not limited thereto, and a half bridge circuit may be configured, for example.

Further, in each of the above-described embodiments, the secondary-side control units 12 and 12A detect the drain currents ID _Q5 and ID _Q6 of the switch elements Q5 and Q6, but not limited thereto, for example, the primary of the transformer T You may detect the electric current which flows into the coil | winding T1.

  Further, in each of the above-described embodiments, the resonant converters 1 and 1A are configured with positive logic.

In each of the above-described embodiments, the drain current ID _Q5 of the switch element Q5 becomes larger than “0” at the timing when the gate-source voltages VGS _Q1 and VGS _Q4 of the switch elements Q1 and Q4 become VH. Although the drain current ID _Q6 of the switch element Q6 becomes larger than “0” at the timing when the gate-source voltages VGS _Q2 and VGS _{Q3 of the} switch elements Q2 and Q3 become VH, it is not limited to this. For example, in the period from when the gate-source voltages VGS _Q2 and VGS _Q3 become VL to when the gate-source voltages VGS _Q1 and VGS _Q4 become VH, the drain current ID _Q5 becomes larger than “0”, and the gate -Even if the drain current ID _Q6 becomes larger than "0" in the period from when the source-to-source voltages VGS _Q1 and VGS _Q4 become VL until the gate-to-source voltages VGS _Q2 and VGS _Q3 become VH. The present invention can be applied.

DESCRIPTION OF SYMBOLS 1, 1A, 1B, 100; Resonance type converter 111; Primary side control part 12, 12A, 12B, 112; Secondary side control part 13; Delay part C1, Cr; Capacitor Lr; Inductor Q1-Q6; Switch element T Transformer Td1; Detection delay time Td2; Delay time VIN; DC power supply

Claims (8)

A transformer, an inductor and a capacitor connected in series to the primary winding of the transformer, and two or more 1 connected to a series circuit in which the primary winding of the transformer, the inductor, and the capacitor are connected in series A resonant converter comprising: a secondary switch element; and two or more secondary switch elements that rectify power generated in the secondary winding of the transformer,
Primary side control means for supplying primary side drive signals to respective control terminals of the two or more primary side switch elements;
Secondary-side control means for supplying a secondary-side drive signal to each control terminal of the two or more secondary-side switch elements,
The secondary side control means includes:
Detecting a current flowing through each of the two or more secondary-side switch elements and generating a detection signal based on the detection result;
Generating a drive permission signal having a pulse width of a predetermined time with reference to a start edge of the primary side drive signal;
A resonance type converter characterized in that a logical product of the detection signal and the drive permission signal is obtained and used as the secondary drive signal.   2. The resonant converter according to claim 1, wherein the predetermined time is equal to a half of a resonance period of a resonance circuit including the inductor and the capacitor.   The predetermined time is equal to a time obtained by subtracting a delay time generated when driving the two or more secondary side switch elements from a half of a resonance period of the resonance circuit having the inductor and the capacitor. The resonant converter according to claim 1, wherein A transformer, an inductor and a capacitor connected in series to the primary winding of the transformer, and two or more 1 connected to a series circuit in which the primary winding of the transformer, the inductor, and the capacitor are connected in series A resonant converter comprising: a secondary switch element; and two or more secondary switch elements that rectify power generated in the secondary winding of the transformer,
Primary side control means for outputting primary side drive signals to be supplied to respective control terminals of the two or more primary side switch elements;
Delay means for delaying the primary side drive signal output from the primary side control means by a predetermined first time and supplying it to the respective control terminals of the two or more primary side switch elements;
Secondary-side control means for supplying a secondary-side drive signal to each control terminal of the two or more secondary-side switch elements,
The secondary side control means includes:
Detecting a current flowing through each of the two or more secondary-side switch elements and generating a detection signal based on the detection result;
Generating a drive permission signal having a pulse width of a second time determined in advance with reference to a start edge of the primary side drive signal before being input to the delay means;
A resonance type converter characterized in that a logical product of the detection signal and the drive permission signal is obtained and used as the secondary drive signal.   5. The resonant converter according to claim 4, wherein the predetermined second time is equal to a half of a resonance period of a resonance circuit including the inductor and the capacitor.   The predetermined second time is a time obtained by subtracting a delay time generated when driving the two or more secondary-side switch elements from a half of a resonance period of the resonance circuit having the inductor and the capacitor. 5. The resonant converter according to claim 4, wherein the resonant converters are equal.   7. The resonant converter according to claim 4, wherein the predetermined first time is equal to a delay time generated when driving the two or more secondary-side switch elements. .   The resonant converter according to any one of claims 1 to 7, wherein the two or more primary-side switch elements constitute a full bridge circuit.

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