CN106817017B - Method for controlling secondary side dead time of power converter - Google Patents

Abstract

The present invention discloses a method for controlling the idle time of the secondary side of a power converter. The method comprises: giving the previous first turn-on time and the current first turn-on time of the primary side corresponding to the power converter; generating a first voltage and a second voltage according to the previous first turn-on time and the current first turn-on time respectively; generating a current first target voltage according to the first voltage, the second voltage and the ideal voltage corresponding to the previous ideal second turn-on time of the secondary side; determining the current second turn-on time of the secondary side according to the first ramp voltage corresponding to the current ideal second turn-on time of the secondary side and the current first target voltage. The difference between the current second turn-on time and the current ideal second turn-on time is the current idle time of the secondary side. Therefore, the present invention can ensure that the primary side and the secondary side of the power converter will not be turned on at the same time.

Description

Method of controlling secondary side dead time of power converter

technical field

The invention relates to a method for controlling the dead time of the secondary side of a power converter, in particular to a method for ensuring power conversion when the frequency of the control signal of the power switch of the primary side of the AC/DC power converter changes suddenly A method in which the primary side and the secondary side of the device are not turned on at the same time.

Background technique

Generally speaking, the conversion efficiency of a switching AC/DC power converter is higher than that of a non-switching AC/DC power converter, but the primary side of the switching AC/DC power converter is in contact with the AC/DC power converter. The secondary sides of the DC power converter cannot be turned on at the same time to prevent the switchable AC/DC power converter from blowing up. When the frequency of the control signal of the power switch on the primary side of the switchable AC/DC power converter does not change suddenly, the primary side of the switchable AC/DC power converter and the AC/DC power converter The secondary sides are not turned on simultaneously. However, if the frequency of the control signal of the power switch on the primary side of the switching AC/DC power converter changes suddenly, the primary side of the AC/DC power converter and the The secondary side may be turned on at the same time, causing the switching AC/DC power converter to fry. Therefore, how to ensure that the primary side of the AC/DC power converter and the secondary side of the AC/DC power converter will not be turned on at the same time when the AC/DC power converter is operating has become a problem for designers of synchronous rectifiers. an important topic.

Contents of the invention

An embodiment of the invention discloses a method for controlling the dead time of a secondary side of a power converter. The method includes specifying a previous first turn-on time and a current first turn-on time corresponding to the primary side of the power converter; and generating a first turn-on time according to the previous first turn-on time and the current first turn-on time respectively. The first voltage and a second voltage; according to the first voltage, the second voltage and the ideal voltage corresponding to the previous ideal second turn-on time of the secondary side, a current first target voltage is generated; according to the corresponding The first slope voltage of the current ideal second turn-on time of the secondary side and the current first target voltage determine the current second turn-on time of the secondary side, wherein the current second turn-on time and the The difference between the current ideal second turn-on time is the current dead time of the secondary side; wherein when the first voltage and the second voltage are different, the current dead time is not equal to the current dead time of the secondary side The previous empty time.

Another embodiment of the present invention discloses a method for controlling the dead time of the secondary side of the power converter. The method includes given a previous ideal turn-on time and a current ideal turn-on time of a secondary side of the power converter; respectively generating a first voltage and a current ideal turn-on time according to the previous ideal turn-on time and the current ideal turn-on time. A second voltage; according to the first voltage and the second voltage, generate a next target voltage; according to the slope voltage corresponding to the next ideal turn-on time of the secondary side and the next target voltage, determine the next target voltage The next turn-on time of the secondary side, wherein the difference between the next turn-on time and the next ideal turn-on time is the next dead time of the secondary side; wherein when the first voltage and the When the second voltages are different, the next dead time is not equal to the current dead time of the secondary side.

Another embodiment of the present invention discloses a method for controlling the dead time of the secondary side of the power converter. The method includes generating a next target voltage based on a detection voltage related to a current output voltage of the secondary side, a reference voltage, and an ideal voltage corresponding to a current ideal turn-on time of the secondary side; according to the corresponding The slope voltage of the next ideal turn-on time of the secondary side and the next target voltage determine the next turn-on time of the secondary side, wherein the difference between the next turn-on time and the next ideal turn-on time is The next dead time of the secondary side; wherein when the first voltage and the second voltage are different, the next dead time is not equal to the current dead time of the secondary side.

The invention discloses a method for controlling the dead time of the secondary side of a power converter. The method is that when the difference between the previous first turn-on time of a synchronization signal and the current first turn-on time is greater than a first predetermined value, the previous ideal second turn-on time of an ideal turn-on signal and the current ideal second turn-on time shortening the power conversion when a difference between times is greater than a second predetermined value or a difference between a detected voltage related to the output voltage of the secondary side of the power converter and a reference voltage is greater than a third predetermined value The turn-on time of the gate control signal of the synchronous switch on the secondary side of the power converter, so as to ensure that the primary side and the secondary side of the power converter will not be turned on at the same time. In addition, when the load coupled to the secondary side of the power converter is large, the present invention can also compensate the output current of the secondary side of the power converter by turning on a compensation switch, so as to respond to the load of the power converter Larger loads on the secondary side.

Description of drawings

FIG. 1 is a schematic diagram of a synchronous rectifier for controlling the dead time of a secondary side of a power converter disclosed in the first embodiment of the present invention.

2 is a schematic diagram illustrating a synchronous signal, an ideal turn-on signal, a first ramp voltage, a first target voltage and a gate control signal.

FIG. 3 is a schematic diagram illustrating the synchronization signal, the ideal turn-on signal and the turn-on time of the power switch when the power converter is in discrete current mode and quasi-resonant mode.

Fig. 4 shows the ideal turn-on signal corresponding to the power converter when the synchronous rectifier uses the ideal turn-on signal corresponding to the secondary side of the power converter to control the dead time of the secondary side of the power converter disclosed in the second embodiment of the present invention. A schematic diagram of determining the next turn-on time of the secondary side of the power converter by the slope voltage of the next ideal turn-on time of the secondary side and the next second target voltage.

FIG. 5 is a schematic diagram of a synchronous rectifier for controlling the dead time of the secondary side of the power converter disclosed in the third embodiment of the present invention.

6 is a schematic diagram of a synchronous rectifier applied on the secondary side of the power converter disclosed in the fourth embodiment of the present invention to compensate the output current of the secondary side of the power converter by using the compensation switch included in the power converter.

FIG. 7 is a flow chart of a method for controlling the secondary side dead time of the power converter disclosed in the fifth embodiment of the present invention.

FIG. 8 is a flow chart of a method for controlling the secondary side dead time of the power converter disclosed in the sixth embodiment of the present invention.

FIG. 9 is a flow chart of a method for controlling the secondary side dead time of the power converter disclosed in the seventh embodiment of the present invention.

Wherein, the reference signs are explained as follows:

100, 600 power converter

102 primary side coil

104 power switch

106 Secondary side coil

108 sync switch

200, 500 synchronous rectifiers

201 Inverter

202 time voltage conversion unit

204 sampling unit

206 Adjustment value generation unit

208 target voltage generation unit

210 gate driver unit

212, 214, 216, 218, 220 pins

222 optocoupler

610 compensation switch

AV1 Current first adjustment value

AV2 Next second adjustment value

AV current adjustment value

CNODE, FBNODE nodes

DT0 Last dead time

DT1 current dead time

DT2 Next dead time

DV detection voltage

GND ground terminal

GCS gate control signal

IPRI current

IV0, IV1 ideal voltage

ISWON0 Last ideal second turn-on time

ISWON1 current ideal second open time

ISWON2 Next ideal second turn-on time

IOUT output current

OUT output terminal

PWM control signal

PWMON0 last first turn-on time

PWMON1 current first turn-on time

PRI primary side

RV1 first ramp voltage

RV2 second ramp voltage

SRGATE0 Last second open time

SRGATE1 current second open time

SEC secondary side

SYN synchronization signal

SRWIDTH ideal turn-on signal

TV1 current first target voltage

TV2 Next second target voltage

TV Next target voltage

TON0, TON1 turn-on time

V1 first voltage

V2 second voltage

V3 third voltage

V4 fourth voltage

VCC output voltage

VREF Reference voltage

700-716, 800-816, 900-916 steps

SRGATE2 Next second open time

PWMON2 next first turn-on time

Detailed ways

Please refer to FIG. 1 . FIG. 1 is a schematic diagram of a synchronous rectifier 200 for controlling the dead time (dead time) of the secondary side SEC of the power converter 100 disclosed in the first embodiment of the present invention, wherein the primary side of the power converter 100 Only the PRI primary coil 102 and a power switch 104 are shown in FIG. 1 , and the power converter 100 is an AC/DC power converter. As shown in FIG. 1 , the synchronous rectifier 200 includes an inverter 201, a time voltage conversion unit 202, a sampling unit 204, an adjustment value generating unit 206, a target voltage generating unit 208, and a gate driving unit 210, The output voltage VCC of the secondary side SEC of the power converter 100 drives the synchronous rectifier 200 through the pin 212 of the synchronous rectifier 200 . As shown in FIG. 1 , when the power switch 104 is turned on, the secondary side coil 106 of the secondary side SEC of the power converter 100 generates a synchronization signal SYN according to the current IPRI flowing through the primary side PRI of the power converter 100 . As shown in FIG. 1 , the time-to-voltage conversion unit 202 can receive the synchronous signal SYN through the pin 214 of the synchronous rectifier 200, wherein the synchronous signal SYN includes the previous first turn-on time PWMON0 and the current first turn-on time of the primary side PRI of the power converter 100. A turn-on time PWMON1 (as shown in Figure 2). In addition, as shown in FIG. 1 , the inverter 201 is used to invert the synchronous signal SYN to generate the ideal turn-on signal SRWIDTH of the synchronous switch 108 corresponding to the secondary side SEC of the power converter 100, wherein as shown in FIG. 2 , the ideal The turn-on signal SRWIDTH includes a previous ideal second turn-on time ISWON0 and a current ideal second turn-on time ISWON1, and the ideal turn-on signal SRWIDTH is related to the discharge time of the secondary side SEC of the power converter 100, wherein the previous ideal second turn-on time is The time ISWON0 and the current ideal second turn-on time ISWON1 are related to the ideal turn-on time of the synchronous switch 108 of the secondary side SEC of the power converter 100 . The time-to-voltage conversion unit 202 can generate a first voltage V1 (corresponding to the previous first on-time PWMON0) and a second voltage V2 (corresponding to the current first on-time PWMON0) according to the previous first on-time PWMON0 and the current first on-time PWMON1 respectively. turn-on time PWMON1), according to the previous ideal second turn-on time ISWON0, an ideal voltage IV0 corresponding to the previous ideal second turn-on time ISWON0 is generated, and according to the current ideal second turn-on time ISWON1, a voltage corresponding to the current ideal second turn-on time ISWON1 is generated The first ramp voltage RV1. As shown in FIG. 1, when the difference between the first voltage V1 and the second voltage V2 sampled by the sampling unit 204 is greater than a first predetermined value, the adjustment value generation unit 206 may to generate a current first adjustment value AV1, wherein the current first adjustment value AV1 is a fixed value or an adjustable value. That is to say, when the difference between the first voltage V1 and the second voltage V2 is not greater than the first predetermined value, the adjustment value generating unit 206 does not generate the current first adjustment value AV1, but outputs a previous adjustment value generation. The first adjustment value output by unit 206 . The target voltage generation unit 208 is coupled to the adjustment value generation unit 206 and the sampling unit 204, and is used to generate a current first target voltage TV1 according to the ideal voltage IV0 corresponding to the previous ideal second turn-on time ISWON0 and the current first adjustment value AV1 That is to say, the target voltage generating unit 208 subtracts the current first adjustment value AV1 from the ideal voltage IV0 corresponding to the previous ideal second turn-on time ISWON0 to generate the current first target voltage TV1. In addition, when the difference between the first voltage V1 and the second voltage V2 is not greater than the first predetermined value, the adjustment value generation unit 206 outputs the first adjustment value output last time. At this time, the target voltage generation unit 208 generates the current first target voltage TV1 according to the ideal voltage IV0 corresponding to the previous ideal second turn-on time ISWON0 and the first adjustment value output by the adjustment value generation unit 206 last time. As shown in FIG. 1 , the gate drive unit 210 is coupled to the time-to-voltage conversion unit 202 and the target voltage generation unit 208, and is used for using the first ramp voltage RV1 corresponding to the current ideal second turn-on time ISWON1 and the current first target voltage TV1 , to determine the current second turn-on time SRGATE1 of the gate control signal GCS of the secondary side SEC of the power converter 100 , wherein the gate control signal GCS is transmitted to the secondary side of the power converter 100 through the pin 216 of the synchronous rectifier 200 The gate of the synchronous switch 108 of the SEC, and the synchronous switch 108 can be turned on and off according to the gate control signal GCS. In addition, as shown in FIG. 1 , the pin 218 of the synchronous rectifier 200 is electrically connected to a ground terminal GND.

As shown in FIG. 2 , the difference between the current second on-time SRGATE1 and the current ideal second on-time ISWON1 is the current dead time DT1 of the secondary side SEC of the power converter 100 . In addition, as shown in FIG. 2, when the first voltage V1 is greater than the second voltage V2 (that is to say, the previous first turn-on time PWMON0 is greater than the current first turn-on time PWMON1 and the difference between the first voltage V1 and the second voltage V2 greater than the first predetermined value), the synchronous rectifier 200 will make the current second turn-on time SRGATE1 less than the previous second turn-on time SRGATE0 of the secondary side SEC of the power converter 100, that is to say, the current dead time DT1 will be greater than the power conversion The previous dead time DT0 of the secondary side SEC of the converter 100, wherein the relationship between the current second turn-on time SRGATE1 and the previous second turn-on time SRGATE0 can be determined by formula (1):

SRGATE1 = SRGATE0 – P*ΔPWMON (1)

As shown in formula (1), the difference between the first on-time PWMON0 of ΔPWMON last time and the current first on-time PWMON1, P is a predetermined ratio, wherein P is greater than 1, and P and the primary side coil 102 and the secondary side coil 106 The turns ratio is related.

In addition, although FIG. 2 is an example where the previous first on-time PWMON0 is greater than the current first on-time PWMON1 , the present invention is not limited to the fact that the previous first on-time PWMON0 is greater than the current first on-time PWMON1 . That is to say, when the current first turn-on time PWMON0 is less than the current first turn-on time PWMON1, resulting in a difference between the second voltage V2 and the first voltage V1 greater than the first predetermined value, the synchronous rectifier 200 will also operate according to the above synchronous rectifier 200 The operating principle makes the current second turn-on time SRGATE1 shorter than the previous second turn-on time SRGATE0 of the secondary side SEC of the power converter 100 to ensure that the primary side PRI and the secondary side SEC of the power converter 100 are not turned on at the same time.

In addition, as shown in FIG. 2 , when the power converter 100 is in a continuous current mode (continuous current mode, CCM), the previous first turn-on time PWMON0 and the current first turn-on time PWMON1 are equal to the primary side of the power converter 100 The turn-on time of the power switch 104 of the PRI. When the power converter 100 is in a discrete current mode (discrete current mode, DCM) and a quasi resonant mode (quasi resonant mode), the previous first turn-on time PWMON0 and the current first turn-on time PWMON1 are greater than those of the power converter 100 Turn-on time of the power switch 104 of the primary side PRI. For example, as shown in FIG. 3 , the previous first turn-on time PWMON0 is longer than the turn-on time TON0 of the power switch 104 , and the current first turn-on time PWMON1 is longer than the turn-on time TON1 of the power switch 104 .

Please refer to FIG. 4 . FIG. 4 shows the dead time of the secondary side SEC of the power converter 100 when the synchronous rectifier 200 uses the ideal turn-on signal SRWIDTH corresponding to the secondary side SEC of the power converter 100 disclosed in the second embodiment of the present invention. , the ideal turn-on signal SRWIDTH, the second ramp voltage RV2 corresponding to the next ideal second turn-on time ISWON2 of the secondary side SEC of the power converter 100 and the next second target voltage TV2 determine the secondary side SEC of the power converter 100 Schematic diagram of the next turn-on time of SRGATE2. As shown in Figure 4, the ideal turn-on signal SRWIDTH includes a previous ideal second turn-on time ISWON0, a current ideal second turn-on time ISWON1 and a next ideal second turn-on time ISWON2, wherein the previous ideal second turn-on time ISWON0, the current The ideal second turn-on time ISWON1 and the next ideal second turn-on time ISWON2 are related to the ideal turn-on time of the synchronous switch 108 of the secondary side SEC of the power converter 100 . After the time-to-voltage conversion unit 202 receives the ideal turn-on signal SRWIDTH, the time-to-voltage conversion unit 202 can generate a third voltage V3 (corresponding to the previous ideal second turn-on time ISWON1) according to the previous ideal second turn-on time ISWON0 and the current ideal second turn-on time ISWON1 respectively. Two turn-on time ISWON0) and a fourth voltage V4 (corresponding to the current ideal second turn-on time ISWON1), and according to the next ideal second turn-on time ISWON2 corresponding to the secondary side SEC of the power converter 100, generate a corresponding next ideal second turn-on time ISWON2 The second ramp voltage RV2 of the second turn-on time ISWON2. As shown in FIG. 4, when the difference between the third voltage V3 and the fourth voltage V4 sampled by the sampling unit 204 is greater than a second predetermined value, the adjustment value generation unit 206 may The difference is to generate the next second adjustment value AV2, wherein the next second adjustment value AV2 is a fixed value or an adjustable value. In addition, when the difference between the third voltage V3 and the fourth voltage V4 is not greater than the second predetermined value, the adjustment value generation unit 206 does not generate the next second adjustment value AV2, but outputs a generation of the previous adjustment value. The second adjustment value output by unit 206 . The target voltage generation unit 208 can generate the next second target voltage TV2 according to the fourth voltage V4 corresponding to the current ideal second turn-on time ISWON1 and the next second adjustment value AV2. The next second adjustment value AV2 is subtracted from the fourth voltage V4 of the second turn-on time ISWON1 to generate the next second target voltage TV2. In addition, when the difference between the third voltage V3 and the fourth voltage V4 is not greater than the second predetermined value, the adjustment value generation unit 206 outputs the second adjustment value output last time. At this time, the target voltage generation unit 208 generates the next second target voltage TV2 according to the fourth voltage V4 corresponding to the current ideal second on-time ISWON1 and the second adjustment value output by the adjustment value generation unit 206 last time. As shown in FIG. 4 , the gate driving unit 210 can determine the gate of the secondary side SEC of the power converter 100 according to the second ramp voltage RV2 corresponding to the next ideal second turn-on time ISWON2 and the next second target voltage TV2. The next second turn-on time SRGATE2 of the control signal GCS, wherein the synchronous switch 108 can be turned on and off according to the gate control signal GCS. In addition, as shown in FIG. 4 , the difference between the next second on-time SRGATE2 and the next ideal second on-time ISWON2 is the next dead time DT2 of the secondary side SEC of the power converter 100 .

As shown in FIG. 4, when the third voltage V3 is greater than the fourth voltage V4 (that is to say, the previous ideal second turn-on time ISWON0 is greater than the current ideal second turn-on time ISWON1 and the difference between the third voltage V3 and the fourth voltage V4 greater than the second predetermined value), the synchronous rectifier 200 will make the next second turn-on time SRGATE2 less than the current second turn-on time SRGATE1 of the secondary side SEC of the power converter 100, that is to say, the next dead time DT2 will be greater than the power supply The current dead time DT1 of the secondary side SEC of the converter 100 .

In addition, although FIG. 4 is an example where the previous ideal second on-time ISWON0 is greater than the current ideal second on-time ISWON1 , the present invention is not limited to the fact that the previous ideal second on-time ISWON0 is greater than the current ideal second on-time ISWON1 . That is to say, when the current ideal second turn-on time ISWON0 is less than the current ideal second turn-on time ISWON1, resulting in a difference between the third voltage V3 and the fourth voltage V4 greater than the second predetermined value, the synchronous rectifier 200 will also operate according to the above synchronous rectifier The operation principle of 200 makes the next second turn-on time SRGATE2 smaller than the current second turn-on time SRGATE1 to ensure that the primary side PRI and the secondary side SEC of the power converter 100 are not turned on at the same time.

Please refer to FIG. 5 . FIG. 5 is a schematic diagram of a synchronous rectifier 500 for controlling the dead time of the secondary side SEC of the power converter 100 disclosed in the third embodiment of the present invention. As shown in FIG. 5 , the time-to-voltage conversion unit 202 can generate an ideal voltage IV1 corresponding to the current ideal second on-time ISWON1 according to the current ideal second on-time ISWON1, and generate an ideal voltage IV1 corresponding to the next ideal second on-time ISWON2 according to the next ideal second on-time ISWON2. The second ramp voltage RV2 of the ideal second turn-on time ISWON2. As shown in FIG. 5 , the adjustment value generation unit 206 can receive a detection voltage DV related to the output voltage VCC of the secondary side SEC of the power converter 100 through the pin 220 of the synchronous rectifier 500, and according to the detection voltage DV and a reference The voltage VREF generates a current adjustment value AV, wherein the current adjustment value AV is a fixed value or an adjustable value. That is to say, when the detection voltage DV changes (for example, the detection voltage DV increases or decreases), causing the difference between the detection voltage DV and the reference voltage VREF to be greater than a third predetermined value, the adjustment value generation unit 206 can adjust the value according to the detection voltage DV and The difference between the reference voltages VREF yields the current adjustment value AV. In addition, when the difference between the detection voltage DV and the reference voltage VREF is not greater than the third predetermined value, the adjustment value generation unit 206 does not generate the current adjustment value AV, but outputs the value output by the previous adjustment value generation unit 206 Adjust the value. In addition, the detection voltage DV is equal to the voltage of a node FBNODE coupled to the output terminal OUT of the secondary side SEC of the power converter 100 or equal to a voltage of the optocoupler 222 coupled to the secondary side SEC of the power converter 100 . The voltage at node CNODE. As shown in FIG. 5 , after the adjustment value generation unit 206 generates the current adjustment value AV, the target voltage generation unit 208 can be based on the ideal voltage IV1 corresponding to the current ideal turn-on time ISWON1 of the secondary side SEC of the power converter 100 and the current adjustment value AV, to generate a target voltage TV. In addition, when the difference between the detection voltage DV and the reference voltage VREF is not greater than the third predetermined value, the adjustment value generation unit 206 outputs the adjustment value output last time. At this time, the target voltage generation unit 208 generates the next target voltage TV according to the ideal voltage IV1 corresponding to the current ideal turn-on time ISWON1 of the secondary side SEC of the power converter 100 and the adjustment value output by the adjustment value generation unit 206 last time. . As shown in FIG. 5 , after the target voltage generating unit 208 generates the next target voltage TV, the gate driving unit 210 can determine according to the second ramp voltage RV2 corresponding to the next ideal second turn-on time ISWON2 and the next target voltage TV. The next second turn-on time SRGATE2 of the gate control signal GCS of the secondary side SEC of the power converter 100, wherein the synchronization signal SYN, the ideal turn-on signal SRWIDTH, the gate control signal GCS, the next target voltage TV and the second ramp voltage The waveform of RV2 can be referred to FIG. 4 , and will not be repeated here.

Since the adjustment value generation unit 206 can generate the current adjustment value AV when the detection voltage DV changes (for example, the detection voltage DV increases or decreases), resulting in the difference between the detection voltage DV and the reference voltage VREF being greater than the third predetermined value, so synchronous The rectifier 500 can make the next second turn-on time SRGATE2 smaller than the current second turn-on time SRGATE1 (that is to say, the next dead time DT2 will be greater than the current dead time DT1), so as to ensure that the primary side PRI of the power converter 100 is consistent with the secondary Side SEC will not be turned on at the same time.

Please refer to FIG. 6. FIG. 6 is a synchronous rectifier applied to the secondary side SEC of the power converter 600 disclosed in the fourth embodiment of the present invention. The compensation switch 610 contained in the power converter 600 is used to compensate the secondary side of the power converter 600. Schematic diagram of the output current IOUT on the side SEC. As shown in FIG. 6 , the difference between the power converter 600 and the power converter 500 is that the power converter 600 also includes a compensation switch 610, wherein the synchronous rectifier applied to the secondary side SEC of the power converter 600 can be as shown in FIG. 1 The synchronous rectifier 200 or the synchronous rectifier 500 shown in FIG. 5 . As shown in FIG. 6 , when the load coupled to the secondary side SEC of the power converter 600 is large, the synchronous rectifier applied to the secondary side SEC of the power converter 600 can utilize the secondary side SEC of the power converter 600 The gate control signal GCS of the synchronous switch 108 or the ideal turn-on signal SRWIDTH of the synchronous switch 108 corresponding to the secondary side SEC of the power converter 600 turns on the compensation switch 610 to compensate the output current IOUT of the secondary side SEC of the power converter 600 . As shown in FIG. 6 , when the compensation switch 610 responds to the gate control signal GCS of the synchronous switch 108 of the secondary side SEC of the power converter 600 or the ideal turn-on signal SRWIDTH of the synchronous switch 108 corresponding to the secondary side SEC of the power converter 600 When turned on, the voltage of the node FBNODE drops, causing the output voltage VCC of the secondary side SEC of the power converter 600 to drop. Because the output voltage VCC of the secondary side SEC of the power converter 600 drops, the primary side PRI of the power converter 600 will transfer more energy to the load of the secondary side SEC of the power converter 600 . In addition, in another embodiment of the present invention, when the load coupled to the secondary side SEC of the power converter 600 is relatively large, the synchronous rectifier applied to the secondary side SEC of the power converter 600 can use the power converter The control signal PWM of the power switch 104 of the primary side PRI of 600 turns on the compensation switch 610 to compensate the output current IOUT of the secondary side SEC of the power converter 600 .

Please refer to FIGS. 1 , 2 and 7 . FIG. 7 is a flow chart of a method for controlling the secondary side dead time of a power converter disclosed in the fifth embodiment of the present invention. The method in FIG. 7 is illustrated by using the power converter 100 and the synchronous rectifier 200 in FIG. 1, and the detailed steps are as follows:

Step 700: start;

Step 702: the time-to-voltage conversion unit 202 can generate the first voltage V1 and the second voltage V2 according to the given previous first turn-on time PWMON0 and the current first turn-on time PWMON1 respectively;

Step 704: Whether the difference between the first voltage V1 and the second voltage V2 is greater than the first predetermined value; if yes, go to step 706; if not, go to step 710;

Step 706: The adjustment value generation unit 206 generates the current first adjustment value AV1 according to the difference between the first voltage V1 and the second voltage V2;

Step 708: The target voltage generation unit 208 generates the current first target voltage TV1 according to the ideal voltage IV0 corresponding to the previous ideal second turn-on time ISWON0 and the current first adjustment value AV1, and proceeds to step 716;

Step 710: the adjustment value generation unit 206 outputs the first adjustment value output by the previous adjustment value generation unit 206;

Step 712: The target voltage generation unit 208 generates the current first target voltage TV1 according to the ideal voltage IV0 corresponding to the previous ideal second turn-on time ISWON0 and the first adjustment value output by the adjustment value generation unit 206, and proceeds to step 716;

Step 714: The time-to-voltage conversion unit 202 generates a first ramp voltage RV1 corresponding to the current ideal second on-time ISWON1 according to the current ideal second on-time ISWON1, and proceeds to step 716;

Step 716: The gate driving unit 210 determines the current first ramp voltage RV1 corresponding to the current ideal second turn-on time ISWON1 and the current first target voltage TV1 of the gate control signal GCS of the secondary side SEC of the power converter 100 2. Start time SRGATE1, jump back to step 702 and step 714.

As shown in FIG. 1 , the time-to-voltage conversion unit 202 can receive the synchronous signal SYN through the pin 214 of the synchronous rectifier 200, wherein the synchronous signal SYN includes the previous first turn-on time PWMON0 and the current first turn-on time of the primary side PRI of the power converter 100. A turn-on time PWMON1 (as shown in Figure 2). In addition, as shown in FIG. 1 , the inverter 201 is used to invert the synchronous signal SYN to generate the ideal turn-on signal SRWIDTH of the synchronous switch 108 corresponding to the secondary side SEC of the power converter 100, wherein as shown in FIG. 2 , the ideal The turn-on signal SRWIDTH includes a previous ideal second turn-on time ISWON0 and a current ideal second turn-on time ISWON1, and the ideal turn-on signal SRWIDTH is related to the discharge time of the secondary side SEC of the power converter 100, wherein the previous ideal second turn-on time is The time ISWON0 and the current ideal second turn-on time ISWON1 are related to the ideal turn-on time of the synchronous switch 108 of the secondary side SEC of the power converter 100 . In step 702 and step 714, the time-to-voltage conversion unit 202 can generate the first voltage V1 (corresponding to the previous first on-time PWMON0) and the second voltage according to the previous first on-time PWMON0 and the current first on-time PWMON1 respectively. V2 (corresponding to the current first turn-on time PWMON1), according to the previous ideal second turn-on time ISWON0, generates an ideal voltage IV0 corresponding to the previous ideal second turn-on time ISWON0, and generates an ideal voltage IV0 corresponding to the current ideal second turn-on time ISWON1 according to the current ideal second turn-on time ISWON1 The first ramp voltage RV1 for the second turn-on time ISWON1. In step 706, when the first voltage V1 sampled by the sampling unit 204 is greater than the second voltage V2 (that is to say, the previous first on-time PWMON0 is greater than the current first on-time PWMON1 and the difference between the first voltage V1 and the second voltage V2 When the difference between the first voltage V1 and the second voltage V2 is greater than the first predetermined value), the adjustment value generation unit 206 can generate the current first adjustment value AV1 according to the difference between the first voltage V1 and the second voltage V2, wherein the current first adjustment value AV1 is a certain value or a Adjustable value. That is to say, when the difference between the first voltage V1 and the second voltage V2 is not greater than the first predetermined value, the adjustment value generation unit 206 will not generate the current first adjustment value AV1 . In step 708 , the target voltage generation unit 208 can subtract the current first adjustment value AV1 from the ideal voltage IV0 corresponding to the previous ideal second turn-on time ISWON0 to generate the current first target voltage TV1 . In addition, in step 710, when the difference between the first voltage V1 and the second voltage V2 is not greater than the first predetermined value, the adjustment value generation unit 206 does not generate the current first adjustment value AV1, but outputs the previous The first adjustment value output by the adjustment value generation unit 206 . In step 712, when the difference between the first voltage V1 and the second voltage V2 is not greater than the first predetermined value, the target voltage generation unit 208 is based on the ideal voltage IV0 corresponding to the previous ideal second turn-on time ISWON0 and the adjustment value The first adjustment value output by the generation unit 206 last time generates the current first target voltage TV1. In step 716, as shown in Figures 1 and 2, the gate drive unit 210 can determine the secondary voltage of the power converter 100 according to the first ramp voltage RV1 corresponding to the current ideal second turn-on time ISWON1 and the current first target voltage TV1. The current second turn-on time SRGATE1 of the gate control signal GCS of the side SEC, wherein the synchronous switch 108 can be turned on and off according to the gate control signal GCS.

As shown in FIG. 2 , the difference between the current second on-time SRGATE1 and the current ideal second on-time ISWON1 is the current dead time DT1 of the secondary side SEC of the power converter 100 . In addition, as shown in FIG. 2, when the first voltage V1 is greater than the second voltage V2 (that is to say, the previous first turn-on time PWMON0 is greater than the current first turn-on time PWMON1 and the difference between the first voltage V1 and the second voltage V2 greater than the first predetermined value), the synchronous rectifier 200 will make the current second turn-on time SRGATE1 less than the previous second turn-on time SRGATE0 of the secondary side SEC of the power converter 100 (that is to say, the current dead time DT1 will be greater than the power conversion The previous dead time DT0 of the secondary side SEC of the power converter 100), to ensure that the primary side PRI and the secondary side SEC of the power converter 100 will not be turned on at the same time

Please refer to FIGS. 1 , 4 and 8 . FIG. 8 is a flow chart of a method for controlling the secondary side dead time of a power converter disclosed in the sixth embodiment of the present invention. The method in FIG. 8 is illustrated by using the power converter 100 and the synchronous rectifier 200 in FIG. 1, and the detailed steps are as follows:

Step 800: start;

Step 802: the time-to-voltage conversion unit 202 can generate a third voltage V3 and a fourth voltage V4 according to the given previous ideal second on-time ISWON0 and the current ideal second on-time ISWON1 respectively;

Step 804: Whether the difference between the third voltage V3 and the fourth voltage V4 is greater than the second predetermined value; if yes, go to step 806; if not, go to step 810;

Step 806: The adjustment value generation unit 206 generates the next second adjustment value AV2 according to the difference between the third voltage V3 and the fourth voltage V4;

Step 808: The target voltage generating unit 208 generates the next second target voltage TV2 according to the fourth voltage V4 corresponding to the current ideal second turn-on time ISWON1 and the next second adjustment value AV2, and proceeds to step 816;

Step 810: the adjustment value generation unit 206 outputs the second adjustment value output by the previous adjustment value generation unit 206;

Step 812: The target voltage generation unit 208 generates the next second target voltage TV2 according to the fourth voltage V4 corresponding to the current ideal second turn-on time ISWON1 and the second adjustment value output by the adjustment value generation unit 206 last time, and proceeds to step 816 ;

Step 814: The time-to-voltage conversion unit 202 generates a second ramp voltage RV2 corresponding to the next ideal second on-time ISWON2 according to the next ideal second on-time ISWON2, and proceeds to step 816;

Step 816: The gate driving unit 210 determines the gate control signal GCS of the secondary side SEC of the power converter 100 according to the second ramp voltage RV2 corresponding to the next ideal second turn-on time ISWON2 and the next second target voltage TV2 At the next second turn-on time SRGATE2 , jump back to step 802 and step 814 .

In step 802 and step 814, as shown in FIG. 4, when the time-to-voltage conversion unit 202 receives the ideal turn-on signal SRWIDTH, the time-to-voltage conversion unit 202 can respectively calculate ISWON1 generates a third voltage V3 (corresponding to the previous ideal second turn-on time ISWON0) and a fourth voltage V4 (corresponding to the current ideal second turn-on time ISWON1), and according to the next ideal value corresponding to the secondary side SEC of the power converter 100 The second on-time ISWON2 generates a second ramp voltage RV2 corresponding to the next ideal second on-time ISWON2 . In step 806, when the difference between the third voltage V3 and the fourth voltage V4 sampled by the sampling unit 204 is greater than the second predetermined value, the adjustment value generation unit 206 may , to generate a next second adjustment value AV2, wherein the next second adjustment value AV2 is a certain value or an adjustable value. In step 808 , the target voltage generation unit 208 can subtract the next second adjustment value AV2 from the fourth voltage V4 corresponding to the current ideal second turn-on time ISWON1 to generate the next second target voltage TV2 . In addition, in step 810, when the difference between the third voltage V3 and the fourth voltage V4 is not greater than the second predetermined value, the adjustment value generation unit 206 does not generate the next second adjustment value AV2, but outputs the previous The second adjustment value output by the secondary adjustment value generation unit 206 . In step 812, when the difference between the third voltage V3 and the fourth voltage V4 is not greater than the second predetermined value, the target voltage generation unit 208 is based on the fourth voltage V4 corresponding to the current ideal second turn-on time ISWON1 and the adjustment value The second adjustment value output by the generating unit 206 last time is used to generate the next second target voltage TV2. In step 816, as shown in FIG. 1 and FIG. 4 , the gate driving unit 210 can determine the voltage of the power converter 100 according to the second ramp voltage RV2 corresponding to the next ideal second turn-on time ISWON2 and the next second target voltage TV2. The next second turn-on time SRGATE2 of the gate control signal GCS of the secondary side SEC, wherein the synchronous switch 108 can be turned on and off according to the gate control signal GCS.

As shown in FIG. 4 , the difference between the next second on-time SRGATE2 and the next ideal second on-time ISWON2 is the next dead time DT2 of the secondary side SEC of the power converter 100 . In addition, as shown in FIG. 4, when the third voltage V3 is greater than the fourth voltage V4 (that is to say, the previous ideal second turn-on time ISWON0 is greater than the current ideal second turn-on time ISWON1 and between the third voltage V3 and the fourth voltage V4 When the difference is greater than the second predetermined value), the synchronous rectifier 200 will make the next second turn-on time SRGATE2 less than the current second turn-on time SRGATE1 of the secondary side SEC of the power converter 100, that is to say, the next dead time DT2 will be It is greater than the current dead time DT1 of the secondary side SEC of the power converter 100 to ensure that the primary side PRI and the secondary side SEC of the power converter 100 will not be turned on at the same time.

Please refer to FIGS. 5 and 9 . FIG. 9 is a flow chart of a method for controlling the secondary side dead time of a power converter disclosed in the seventh embodiment of the present invention. The method in FIG. 9 is illustrated by using the power converter 100 and the synchronous rectifier 500 in FIG. 5, and the detailed steps are as follows:

Step 900: start;

Step 902: the time-to-voltage conversion unit 202 generates an ideal voltage IV1 corresponding to the current ideal second on-time ISWON1 according to the current ideal second on-time ISWON1;

Step 904: Whether the difference between the detected voltage DV of the output voltage VCC of the secondary side SEC of the power converter 100 and the reference voltage VREF is greater than a third predetermined value; if yes, go to step 906; if not, go to step 910 ;

Step 906: The adjustment value generation unit 206 generates the current adjustment value AV according to the difference between the detection voltage DV and the reference voltage VREF;

Step 908: The target voltage generation unit 208 generates the next target voltage TV according to the ideal voltage IV1 corresponding to the current ideal second turn-on time ISWON1 and the current adjustment value AV, and proceeds to step 916;

Step 910: the adjustment value generation unit 206 outputs the adjustment value output by the previous adjustment value generation unit 206;

Step 912: The target voltage generation unit 208 generates the next target voltage TV according to the ideal voltage IV1 corresponding to the current ideal second turn-on time ISWON1 and the adjustment value output by the adjustment value generation unit 206 last time, and proceeds to step 916;

Step 914: the time-to-voltage conversion unit 202 generates a second ramp voltage RV2 corresponding to the next ideal second on-time ISWON2 according to the corresponding next ideal second on-time ISWON2, and proceeds to step 916;

Step 916: The gate driving unit 210 determines the next second gate control signal GCS of the secondary side SEC of the power converter 100 according to the second ramp voltage RV2 of the next ideal second turn-on time ISWON2 and the next target voltage TV. 2. Start time SRGATE2, jump back to step 902 and step 914.

In step 902 and step 914, as shown in FIG. 5 , the time-to-voltage conversion unit 202 can generate an ideal voltage IV1 corresponding to the current ideal second on-time ISWON1 according to the current ideal second on-time ISWON1, and generate an ideal voltage IV1 corresponding to the next ideal second on-time The turn-on time ISWON2 generates a second ramp voltage RV2 corresponding to the next ideal second turn-on time ISWON2 . In step 906, as shown in FIG. 5 , the adjustment value generation unit 206 may receive the detection voltage DV related to the output voltage VCC of the secondary side SEC of the power converter 100 through the pin 220 of the synchronous rectifier 500, and according to the detection voltage DV and the reference voltage VREF generate a current adjustment value AV, wherein the current adjustment value AV is a fixed value or an adjustable value. That is to say, when the detection voltage DV changes (for example, the detection voltage DV increases or decreases), causing the difference between the detection voltage DV and the reference voltage VREF to be greater than the third predetermined value, the adjustment value generating unit 206 can adjust the value according to the detection voltage DV and the reference The difference between voltages VREF yields the present adjustment value AV. In addition, the detection voltage DV is equal to the voltage of the node FBNODE coupled to the output terminal OUT of the secondary side SEC of the power converter 100 or equal to the node CNODE of the optocoupler 222 coupled to the secondary side SEC of the power converter 100 voltage. In step 908, as shown in FIG. 5 , after the adjustment value generation unit 206 generates the current adjustment value AV, the target voltage generation unit 208 can generate the ideal voltage corresponding to the current ideal turn-on time ISWON1 of the secondary side SEC of the power converter 100 IV1 and the current adjustment value AV generate the next target voltage TV. In addition, in step 910, when the difference between the detection voltage DV and the reference voltage VREF is not greater than the third predetermined value, the adjustment value generation unit 206 does not generate the current adjustment value AV, but outputs the previous adjustment value generation unit 206 output adjustment value. In step 912, when the difference between the detection voltage DV and the reference voltage VREF is not greater than the third predetermined value, the target voltage generation unit 208 is based on the current ideal turn-on time ISWON1 corresponding to the secondary side SEC of the power converter 100. The voltage IV1 and the previous adjustment value output by the adjustment value generation unit 206 generate the next target voltage TV. In step 916, as shown in FIG. 5 , after the target voltage generating unit 208 generates the next target voltage TV, the gate driving unit 210 can generate the next target voltage TV according to the second ramp voltage RV2 corresponding to the next ideal second turn-on time ISWON2 and the next The target voltage TV determines the next second turn-on time SRGATE2 of the gate control signal GCS of the secondary side SEC of the power converter 100 .

Since the adjustment value generation unit 206 can generate the current adjustment value AV when the detection voltage DV changes (for example, the detection voltage DV increases or decreases), resulting in the difference between the detection voltage DV and the reference voltage VREF being greater than the third predetermined value, so synchronous The rectifier 500 can make the next second turn-on time SRGATE2 smaller than the current second turn-on time SRGATE1 (that is to say, the next dead time DT2 will be greater than the current dead time DT1), so as to ensure that the primary side PRI of the power converter 100 is consistent with the secondary Side SEC will not be turned on at the same time.

To sum up, the method for controlling the dead time of the secondary side of the power converter disclosed in the present invention is that when the difference between the previous first turn-on time of the synchronization signal and the current first turn-on time is greater than the first predetermined value, The difference between the previous ideal second on time of the ideal on signal and the current ideal second on time is greater than a second predetermined value or a difference between a detection voltage and a reference voltage related to the output voltage of the secondary side of the power converter When greater than the third predetermined value, the turn-on time of the gate control signal of the synchronous switch on the secondary side of the power converter is shortened to ensure that the primary side and the secondary side of the power converter are not turned on at the same time. In addition, when the load coupled to the secondary side of the power converter is large, the present invention can also compensate the output current of the secondary side of the power converter by turning on the compensation switch, so as to cope with the relatively large load of the secondary side of the power converter. large load.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (24)

1. it is a kind of control power adapter secondary side idle time method, characterized by comprising:

Previous first opening time and current first opening time of the primary side of the given corresponding power adapter；

Respectively according to previous first opening time and current first opening time, a first voltage and one second is generated Voltage；

According to the ideal of the second opening time of preceding subideal of the first voltage, the second voltage and the corresponding secondary side Voltage generates a current first target voltage；And

According to the first slope voltage of current ideal second opening time of the correspondence secondary side and the current first object Voltage determines current second opening time of the secondary side, wherein current second opening time and the current ideal The difference of second opening time is the current idle time of the secondary side；

Wherein when the first voltage and the second voltage difference, the current idle time is not equal to the secondary side Previous idle time.

2. the method as described in claim 1, which is characterized in that when the difference between the second voltage and the first voltage is big When a first predetermined value, the current idle time is greater than the previous idle time, and current second opening time It is equal to previous first opening time and current first unlatching with the difference of previous second opening time of the secondary side The product of the difference and a predetermined ratio of time, wherein the predetermined ratio is greater than 1, and the line of the predetermined ratio and the primary side It encloses related with the turn ratio of the coil of the secondary side.

3. the method as described in claim 1, which is characterized in that when the power adapter is in a continuous current mode, The power for the primary side that previous first opening time is equal to the power adapter with current first opening time is opened The opening time of pass, and when the power adapter is in a stray currents mode and quasi-resonant mode, described previous When one opening time and current first opening time are greater than the unlatching of the power switch of the primary side of the power adapter Between.

4. the method as described in claim 1, which is characterized in that the ideal of the secondary side of the corresponding power adapter opens letter It number is converted comprising preceding second opening time of subideal and current ideal second opening time, and with the corresponding power supply The synchronization signal reverse phase of the primary side of device, wherein the synchronization signal corresponds to the power switch of the primary side of the power adapter Opening time.

5. the method as described in claim 1, which is characterized in that according to the first voltage, the second voltage and corresponding institute The desired voltage of second opening time of subideal before stating, generating the current first target voltage includes:

When the difference between the second voltage and the first voltage is greater than a first predetermined value, a current the first adjustment is generated Value；And

According to the desired voltage and the current the first adjustment value of correspondence preceding second opening time of subideal, the mesh is generated Preceding first target voltage.

6. the method as described in claim 1, which is characterized in that according to the first voltage, the second voltage and corresponding institute The desired voltage of second opening time of subideal before stating, generating the current first target voltage includes:

When the difference between the second voltage and the first voltage is not more than a first predetermined value, output one is previous to be exported The first adjustment value；And

According to the desired voltage and previous the exported the first adjustment value of correspondence preceding second opening time of subideal, produce The raw current first target voltage.

7. the method as described in claim 1, which is characterized in that when being opened according to current ideal the second of the correspondence secondary side Between first slope voltage and the current first target voltage, determine that current second opening time of the secondary side includes:

According to current ideal second opening time, the first slope voltage is generated；And

According to the current first target voltage and the first slope voltage, current second opening time is determined.

8. the method as described in claim 1, which is characterized in that also include:

Respectively according to the second opening time of preceding subideal of the secondary side and current ideal second opening time, one is generated Tertiary voltage and one the 4th voltage；

When the difference between the 4th voltage and the tertiary voltage is greater than a second predetermined value, a next second adjustment is generated Value；

According to the 4th voltage and next second adjustment value, next second target voltage is generated；

According to next ideal second opening time of the correspondence secondary side, one second ramp voltage is generated；And

According to next second target voltage and second ramp voltage, when determining that next the second of the secondary side is opened Between.

9. method according to claim 8, which is characterized in that preceding second opening time of subideal, the current ideal Second opening time and next ideal second opening time relate to the secondary side of the power adapter synchronize open When the current second unlatching of the ideal opening time of pass and next second opening time of the secondary side and the secondary side Between relate to the power adapter secondary side synchronous switch opening time.

10. the method as described in claim 1, which is characterized in that also include:

It is opened according to the ideal of synchronous switch of the grid control signal of the synchronous switch of the secondary side, the corresponding secondary side The control signal of the power switch of signal or the primary side, it is described to compensate to open a compensating switch of the power adapter The output electric current of secondary side.

11. it is a kind of control power adapter secondary side idle time method, characterized by comprising:

Give the preceding subideal opening time and current ideal opening time of the secondary side of the power adapter；

Respectively according to the preceding subideal opening time and the current ideal opening time, a first voltage and one second is generated Voltage；

According to the first voltage and the second voltage, a next target voltage is generated；And

According to the ramp voltage and next target voltage of next ideal opening time of the correspondence secondary side, described in decision Next opening time of secondary side, wherein the difference of next opening time and next ideal opening time are described secondary Next idle time of side；

Wherein when the first voltage and the second voltage difference, next idle time is not equal to the secondary side Idle time at present.

12. method as claimed in claim 11, which is characterized in that the preceding subideal opening time, the current ideal are opened It opens the time and the ideal of synchronous switch of secondary side that next ideal opening time relates to the power adapter is opened The current opening time of the next opening time and the secondary side of opening time and the secondary side relate to the power supply The opening time of the synchronous switch of the secondary side of converter.

13. method as claimed in claim 11, which is characterized in that the ideal of the secondary side of the corresponding power adapter is opened Signal includes the preceding subideal opening time, current ideal second opening time and next ideal opening time, And with the synchronization signal reverse phase of the primary side of the corresponding power adapter, wherein the synchronization signal corresponds to power supply conversion The opening time of the power switch of the primary side of device.

14. method as claimed in claim 11, which is characterized in that according to the first voltage and the second voltage, generate Next target voltage includes:

When the difference between the second voltage and the first voltage is greater than a predetermined value, an adjusted value is generated；And

According to the second voltage and the adjusted value, next target voltage is generated.

15. method as claimed in claim 11, which is characterized in that according to the first voltage and the second voltage, generate Next target voltage includes:

When the difference between the second voltage and the first voltage is not more than a predetermined value, previous an exported tune is exported Whole value；And

According to the second voltage and previous the exported adjusted value, next target voltage is generated.

16. method as claimed in claim 11, which is characterized in that according to next ideal opening time of the correspondence secondary side Ramp voltage and next target voltage, determine that next opening time of the secondary side includes:

According to next ideal opening time, the ramp voltage is generated；And

According to next target voltage and the ramp voltage, next opening time is determined.

17. method as claimed in claim 11, which is characterized in that when the first voltage and the second voltage difference, Next idle time is less than the current idle time, and the current unlatching of next opening time and the secondary side The difference of time is equal to the product of the previous opening time of the secondary side and the difference and a predetermined ratio of the current opening time, Described in predetermined ratio be greater than 1, and the coil of the primary side of the predetermined ratio and the power adapter and the secondary side Coil turn ratio it is related.

18. method as claimed in claim 11, which is characterized in that also include:

It is opened according to the ideal of synchronous switch of the grid control signal of the synchronous switch of the secondary side, the corresponding secondary side The control signal of the power switch of the primary side of signal or the power adapter, the compensation for opening the power adapter are opened It closes to compensate the output electric current of the secondary side.

19. it is a kind of control power adapter secondary side idle time method, characterized by comprising:

According to one of the current output voltage about secondary side detection voltage, a reference voltage and the corresponding secondary side The current ideal opening time desired voltage, generate a next target voltage；And

According to the ramp voltage and next target voltage of next ideal opening time of the correspondence secondary side, described in decision Next opening time of secondary side, wherein the difference of next opening time and next ideal opening time are described secondary Next idle time of side, and when not waiting the current ideal opening time and next ideal opening time, corresponding institute The current idle time of ideal opening time and next idle time at present is stated to differ.

20. method as claimed in claim 19, which is characterized in that according to the detection voltage, the reference voltage and correspondence The desired voltage of the current ideal opening time of the secondary side, generating next target voltage includes:

When the difference between the detection voltage and the reference voltage is greater than a third predetermined value, an adjusted value is generated；And

According to the desired voltage of the correspondence current ideal opening time and the adjusted value, next target voltage is generated.

21. method as claimed in claim 19, which is characterized in that according to the detection voltage, the reference voltage and correspondence The desired voltage of the current ideal opening time of the secondary side, generating next target voltage includes:

When the difference between the detection voltage and the reference voltage is not more than a third predetermined value, output one is previous to be exported Adjusted value；And

According to the desired voltage of the correspondence current ideal opening time and previous the exported adjusted value, under generation is described One target voltage.

22. method as claimed in claim 19, which is characterized in that the detection voltage is coupled to the output of the secondary side The voltage of one node at end.

23. method as claimed in claim 19, which is characterized in that the detection voltage is coupled to the optocoupler of the secondary side The voltage of one node of clutch.

24. method as claimed in claim 19, which is characterized in that also include:

It is opened according to the ideal of synchronous switch of the grid control signal of the synchronous switch of the secondary side, the corresponding secondary side The control signal of the power switch of the primary side of signal or the power adapter, the compensation for opening the power adapter are opened It closes to compensate the output electric current of the secondary side.