Secondary controller applied to secondary side of power converter and method of operation thereof

Abstract

A secondary controller applied to a secondary side of a power converter and an operating method thereof are disclosed. The secondary controller includes a control signal generating circuit and a gate control signal generating circuit. The gate control signal generating circuit generates a gate control signal and generates an injection signal according to the gate control signal. The control signal generating circuit generates a gate pulse control signal when a superimposed voltage is less than a reference voltage. The superimposed voltage is related to an output voltage of the power converter and the injection signal. The gate control signal generating circuit also generates a gate pulse signal according to the gate pulse control signal to turn on a primary side of the power converter. Therefore, because the primary side of the power converter is turned on by the superimposed voltage, when the output voltage is lower than the target voltage, the ripples of the feedback voltage do not occur in groups and the power converter does not generate audio noise.

Description

Technical Field

[0001] This invention relates to a secondary controller and its operating method applied to the secondary side of a power converter, and more particularly to a secondary controller and its operating method that can operate a superimposed voltage when a capacitor coupled to the secondary side of the power converter has a low series internal resistance value, so that ripples on the feedback voltage of the secondary side of the power converter do not appear in clusters and the power converter does not produce audio noise. Background Technology

[0002] In existing technologies, when the grounding capacitor (e.g., a solid-state capacitor) coupled to the secondary side of a power converter has a low electrical series internal resistance, the feedback voltage received by the secondary controller applied to the secondary side of the power converter will have small ripple. This feedback voltage is related to the output voltage of the power converter's secondary side. When the output voltage of the power converter's secondary side is lower than a target voltage, the secondary controller will, based on the feedback voltage, cause the primary controller on the primary side of the power converter to activate the power switch on the primary side, resulting in a transfer from the primary side to the secondary side to boost the output voltage. However, the operating frequency of the power switch may rapidly increase in a short time due to the small ripple of the feedback voltage, leading to clusters of ripple and audio noise in the power converter. Therefore, addressing the shortcomings of the existing technology has become an important issue for the designers of the secondary controller. Summary of the Invention

[0003] One embodiment of the present invention discloses a secondary controller applied to the secondary side of a power converter. The secondary controller includes a control signal generation circuit and a gate control signal generation circuit. The gate control signal generation circuit is used to generate a gate control signal and, based on the gate control signal, generate an injection signal. The control signal generation circuit is coupled to the output terminal of the secondary side of the power converter and the gate control signal generation circuit, and is used to generate a gate pulse control signal when a superimposed voltage is less than a reference voltage, wherein the superimposed voltage relates to the output voltage of the power converter and the injection signal. The gate control signal generation circuit is further used to generate a gate pulse signal based on the gate pulse control signal, and the gate pulse signal is used to turn on the primary side of the power converter.

[0004] Another embodiment of the present invention discloses an operation method of a secondary controller applied to the secondary side of a power converter, the secondary controller comprising a control signal generation circuit and a gate control signal generation circuit. The operation method includes the gate control signal generation circuit generating a gate control signal and generating an injection signal based on the gate control signal; the control signal generation circuit generating a superimposed voltage based on the output voltage of the power converter and the injection signal; when the superimposed voltage is greater than a reference voltage, the control signal generation circuit generating a short-circuit control signal after the gate control signal to a short-circuit winding switch to cause the short-circuit winding switch to open according to the short-circuit control signal; when the superimposed voltage is less than the reference voltage, the control signal generation circuit generating a gate pulse control signal; and the gate control signal generation circuit generating a gate pulse signal based on the gate pulse control signal, wherein the gate pulse signal is used to turn on the primary side of the power converter.

[0005] This invention discloses a secondary controller and its operating method applied to the secondary side of a power converter. The secondary controller and operating method utilize a superimposed voltage (with ripple on the feedback voltage of the secondary side of the power converter and greater than the ripple on the feedback voltage) to enable the primary controller on the primary side of the power converter to control the switching on of the primary side. Therefore, when the output voltage of the secondary side of the power converter is lower than a target voltage, the operating frequency of the power switch on the primary side of the power converter will not increase rapidly in a short time because the superimposed voltage is greater than the ripple on the feedback voltage. Therefore, compared to the prior art, because the secondary controller disclosed in this invention uses the superimposed voltage to enable the primary controller to control the switching on of the primary side of the power converter, rather than directly using the feedback voltage, the ripple on the feedback voltage will not appear in clusters when the output voltage of the secondary side of the power converter is lower than the target voltage, and the power converter will not exhibit audio noise. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of a secondary controller applied to the secondary side of a power converter, as disclosed in the first embodiment of the present invention.

[0007] Figure 2 This is a schematic diagram illustrating the feedback voltage, reference voltage, gate control signal, injection signal, and superimposed voltage.

[0008] Figure 3 This is a flowchart of an operation method for a secondary controller applied to the secondary side of a power converter, as disclosed in the second embodiment of the present invention.

[0009] The reference numerals in the attached figures are explained as follows:

[0010] 100 power converter

[0011] 101 capacitor

[0012] 102 Synchronous Switch

[0013] 103 voltage divider circuit

[0014] 104 Power Switch

[0015] 106 Short-circuit winding switch

[0016] 108 secondary windings

[0017] 110 Primary winding

[0018] 112 Primary auxiliary winding

[0019] 114 Primary Controller

[0020] 115 resistor

[0021] 200 secondary controllers

[0022] 202 Control Signal Generation Circuit

[0023] 206 Gate Control Signal Generation Circuit

[0024] 2022 Current Source

[0025] 2024 comparator

[0026] 2026 Logic Unit

[0027] 2028 Switch

[0028] A circle

[0029] GCS gate control signal

[0030] GPCS gate pulse control signal

[0031] GPS gate pulse signal

[0032] IPRI primary side current

[0033] IS Injection Signal

[0034] IC Injection Current

[0035] PGCS primary side gate control signal

[0036] PRI primary side

[0037] SEC secondary side

[0038] SCS short-circuit control signal

[0039] SV superimposed voltage

[0040] T1, T2, T3 time

[0041] VSW secondary voltage

[0042] VFB Feedback Voltage

[0043] VOUT output voltage

[0044] VC voltage

[0045] VD Detection Voltage

[0046] VIN Input Voltage

[0047] VREF reference voltage

[0048] Steps 300-312 Detailed Implementation

[0049] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a secondary controller 200 applied to the secondary side SEC of a power converter 100, as disclosed in the first embodiment of the present invention. The secondary controller 200 is located on the secondary side SEC of the power converter 100. A capacitor 101 coupled to the secondary side SEC of the power converter 100 has a low electrical series internal resistance. The power converter 100 is a flyback power converter. The secondary controller 200 includes a control signal generation circuit 202 and a gate control signal generation circuit 206. The control signal generation circuit 202 is coupled to the output terminal of the secondary side SEC of the power converter 100 and the gate control signal generation circuit 206. Furthermore, the ground level of the primary side PRI of the power converter 100 and the ground level of the secondary side SEC of the power converter 100 may be the same or different, and as... Figure 1 As shown, the input voltage VIN of the primary side PRI of the power converter 100 is generated by rectifying an AC voltage through a bridge rectifier.

[0050] like Figure 1As shown, the control signal generation circuit 202 includes a current source 2022, a comparator 2024, and a logic unit 2026. A first input terminal of the comparator 2024 is used to receive a feedback voltage VFB, which is generated by dividing the output voltage VOUT of the secondary side SEC of the power converter 100 through a voltage divider circuit 103. A second input terminal of the comparator 2024 is used to receive a reference voltage VREF. Furthermore, the output voltage VOUT has relatively small ripple due to the low series resistance of capacitor 101, resulting in relatively small ripple on the feedback voltage VFB (e.g., ...). Figure 2 (As shown in circle A). Additionally, as... Figure 1 As shown, the gate control signal generation circuit 206 can generate an injection signal IS to a switch 2028 within the control signal generation circuit 202 based on a gate control signal GCS it generates. Therefore, when the switch 2028 is turned on, an injection current IC provided by the current source 2022 charges the first input terminal of the comparator 2024, resulting in a superimposed voltage SV at the first input terminal of the comparator 2024. Since the superimposed voltage SV is determined by the feedback voltage VFB and the width of the injection signal IS, the superimposed voltage SV is equal to the sum of the ripple on the feedback voltage VFB and the voltage corresponding to the width of the injection signal IS; that is, the superimposed voltage SV is greater than the ripple on the feedback voltage VFB. Furthermore, since the feedback voltage VFB is generated by the output voltage VOUT and the voltage divider circuit 103, the superimposed voltage SV also has ripple on the output voltage VOUT. Additionally, in one embodiment of the present invention, the width of the injection signal IS can be proportional to the discharge time of the secondary side SEC of the power converter 100. Furthermore, the gate control signal generation circuit 206 can generate a gate control signal GCS based on the secondary side voltage VSW. During the activation period of the gate control signal GCS, the synchronous switch 102 can be turned on according to the gate control signal GCS, and the activation period of the gate control signal GCS is related to the discharge time of the secondary side SEC of the power converter 100. Additionally, the present invention is not limited to injecting current IC to the first input terminal of comparator 2024 to generate a superimposed voltage SV; that is, any method that applies a voltage to the feedback voltage VFB during the activation period of the gate control signal GCS to generate a superimposed voltage SV falls within the scope of the present invention.

[0051] like Figure 2 As shown, at a time T1, the feedback voltage VFB begins to decrease, causing the superimposed voltage SV to also begin to decrease. Figure 2 As shown, at a time T2, the superimposed voltage SV begins to be less than the reference voltage VREF. At this time, as... Figure 1As shown, comparator 2024 enables logic unit 2026 to turn off a short-circuit control signal SCS and generates a gate pulse control signal GPCS after the gate control signal GCS to the gate control signal generation circuit 206. Since the superimposed voltage SV is less than the reference voltage VREF, indicating a lower feedback voltage VFB (i.e., a lower output voltage VOUT), the frequency at which logic unit 2026 generates the gate pulse control signal GPCS will increase. Furthermore, the operating principle of the short-circuit control signal SCS and the short-circuit winding switch 106 receiving the short-circuit control signal SCS can be found in the US patent (US10756639B2) regarding the short-circuit control signal SCS and the short-circuit winding switch 106, and will not be repeated here. Additionally, as... Figure 1 As shown, the short-circuit winding switch 106 is coupled to the secondary winding 108 of the power converter 100. There is a predetermined time between the gate control signal GCS and the short-circuit control signal SCS, and this predetermined time can be changed according to the needs of the power converter 100 designer. Therefore, the gate control signal generation circuit 206 can generate a gate pulse signal GPS based on the gate pulse control signal GPCS. The gate pulse signal GPS is used to turn on the primary side PRI of the power converter 100, wherein the primary side PRI and the secondary side SEC of the power converter 100 will not be turned on simultaneously. Furthermore, the operating principle of the gate pulse signal GPS enabling the primary side PRI of the power converter 100 can also be referred to the content of the gate pulse control signal GPCS and the gate pulse signal GPS disclosed in the US Patent (US10756639B2) (for example, the synchronous switch 102 of the secondary side SEC of the power converter 100 can be enabled according to the gate pulse signal GPS, and during the enabling period of the gate pulse signal GPS, the change of the secondary side voltage VSW caused by the enabling of the synchronous switch 102 will be coupled to the primary side PRI of the power converter 100 through the secondary side winding 108 and the primary side auxiliary winding 112 of the power converter 100, wherein the primary controller 114 can generate the primary side gate control signal PGCS to the power switch 104 to enable the primary side PRI of the power converter 100 according to the change of the secondary side voltage VSW), so it will not be described again here.

[0052] In addition, such as Figure 2 As shown, at time T3, the superimposed voltage SV is greater than the reference voltage VREF. At this time, as... Figure 1As shown, comparator 2024 can cause logic unit 2026 to turn off the gate pulse control signal GPCS and enable the short-circuit control signal SCS to the short-circuit winding switch 106 so that the short-circuit winding switch 106 is turned on according to the short-circuit control signal SCS. Since the superimposed voltage SV is greater than the reference voltage VREF, it means that the feedback voltage VFB is higher (that is, the output voltage VOUT is higher), so the frequency at which logic unit 2026 generates the gate pulse control signal GPCS will decrease. Therefore, since the secondary controller 200 uses the superimposed voltage SV (which relates to and is greater than the ripple on the feedback voltage VFB) to enable the primary controller 114 to control the primary side PRI of the power converter 100, when the output voltage VOUT is lower than a target voltage (related to the reference voltage VREF), the operating frequency of the power switch 104 of the primary side PRI of the power converter 100 will not rise rapidly in a short time because the superimposed voltage SV is greater than the ripple on the feedback voltage VFB. This prevents the ripple on the feedback voltage VFB from appearing in clusters and prevents audio noise from occurring in the power converter 100. Furthermore, after the short-circuit winding switch 106 is turned on according to the short-circuit control signal SCS, the secondary side voltage VSW will not resonate, ensuring that the primary side PRI of the power converter 100 is turned off.

[0053] In addition, such as Figure 1 As shown, the description of the primary winding 110, secondary winding 108, voltage VC, detection voltage VD, primary current IPRI, and resistor 115 of the power converter 100 can also be found in the content disclosed in US Patent (US10756639B2) regarding the primary winding 110, secondary winding 108, voltage VC, detection voltage VD, primary current IPRI, and resistor 115, so it will not be repeated here.

[0054] Please refer to Figure 1-3 , Figure 3 This is a flowchart of an operation method for a secondary controller applied to the secondary side of a power converter, as disclosed in the second embodiment of the present invention. Figure 3 The operation method is to use Figure 1 The power converter 100, secondary controller 200, and primary controller 114 are described in detail below:

[0055] Step 300: Begin;

[0056] Step 302: During the period when the secondary side SEC of the power converter 100 is turned on after the primary side PRI of the power converter 100 is turned off, the gate control signal generation circuit 206 generates a gate control signal GCS based on the secondary side voltage VSW of the secondary side SEC of the power converter 100, and generates an injection signal IS based on the gate control signal GCS.

[0057] Step 304: The control signal generation circuit 202 generates a superimposed voltage SV based on the output voltage VOUT of the power converter 100 and the injected signal IS;

[0058] Step 306: Is the superimposed voltage SV greater than the reference voltage VREF? If yes, proceed to step 308; if yes, proceed to step 310.

[0059] Step 308: The control signal generation circuit 202 generates a short-circuit control signal SCS to the short-circuit winding switch 106 so that the short-circuit winding switch 106 opens according to the short-circuit control signal SCS, and then jumps back to step 302.

[0060] Step 310: The control signal generation circuit 202 generates the gate pulse control signal GPCS;

[0061] Step 312: The gate control signal generation circuit 206 generates a gate pulse signal GPS according to the gate pulse control signal GPCS to enable the primary side PRI of the power converter 100, and then jumps back to step 302.

[0062] In step 302, after the primary side PRI of the power converter 100 is turned on, the primary controller 114 can decide whether to turn off the primary side PRI of the power converter 100 based on the detected voltage VD, wherein the secondary side voltage VSW of the secondary side SEC of the power converter 100 changes as the primary side PRI of the power converter 100 is turned on. During the period when the secondary side SEC of the power converter 100 is turned on after the primary side PRI of the power converter 100 is turned off, the gate control signal generation circuit 206 can generate a gate control signal GCS based on the secondary side voltage VSW of the secondary side SEC of the power converter 100, and generate an injection signal IS to the switch 2028 in the control signal generation circuit 202 based on the gate control signal GCS.

[0063] In step 304, when switch 2028 is turned on, the injected current IC provided by current source 2022 charges the first input terminal of comparator 2024, resulting in a superimposed voltage SV at the first input terminal of comparator 2024. Since the superimposed voltage SV is determined by the feedback voltage VFB and the width of the injected signal IS, it is equal to the sum of the ripple on the feedback voltage VFB and the voltage corresponding to the width of the injected signal IS. In other words, the superimposed voltage SV is greater than the ripple on the feedback voltage VFB. Furthermore, in one embodiment of the present invention, the width of the injected signal IS can be proportional to a predetermined ratio to the discharge time of the secondary side SEC of the power converter 100.

[0064] In step 308, as Figure 2As shown, at time T3, because the superimposed voltage SV is greater than the reference voltage VREF, the control signal generation circuit 202 will turn off the gate pulse control signal GPCS at time T3 and generate a short-circuit control signal SCS to the short-circuit winding switch 106 so that the short-circuit winding switch 106 turns on according to the short-circuit control signal SCS. Furthermore, there is a predetermined time between the gate control signal GCS and the short-circuit control signal SCS, and this predetermined time can be changed according to the needs of the designer of the power converter 100. Therefore, as... Figure 2 As shown, after the short-circuit winding switch 106 is turned on, the secondary side voltage VSW will not resonate, ensuring that the primary side PRI of the power converter 100 is turned off. Furthermore, after the short-circuit winding switch 106 is turned on, if the load coupled to the secondary side SEC of the power converter 100 suddenly becomes heavier, causing the output voltage VOUT of the power converter 100 to decrease and the superimposed voltage SV to be less than the reference voltage VREF, the control signal generation circuit 202 will generate a gate pulse control signal GPCS to the gate control signal generation circuit 206. Then, the gate control signal generation circuit 206 will generate a gate pulse signal GPS according to the gate pulse control signal GPCS to turn on the primary side PRI of the power converter 100.

[0065] In step 310, as Figure 2 As shown, at time T1, the feedback voltage VFB begins to decrease, causing the superimposed voltage SV to also begin to decrease. Figure 2 As shown, at time T2, the superimposed voltage SV begins to be less than the reference voltage VREF. At this time, as... Figure 1 As shown, the control signal generation circuit 202 can turn off the short-circuit control signal SCS and generate a gate pulse control signal GPCS after the gate control signal GCS to the gate control signal generation circuit 206. Since the superimposed voltage SV is less than the reference voltage VREF, indicating that the feedback voltage VFB is low (that is, the output voltage VOUT is low), the frequency of the gate pulse control signal GPCS generated by the logic unit 2026 will increase. Therefore, in step 312, the gate control signal generation circuit 206 can generate a gate pulse signal GPS according to the gate pulse control signal GPCS, and the gate pulse signal GPS is used to turn on the primary side PRI of the power converter 100, wherein the primary side PRI of the power converter 100 and the secondary side SEC of the power converter 100 will not be turned on simultaneously.

[0066] In summary, the secondary controller and its operating method disclosed in this invention, applied to the secondary side of a power converter, utilize the superimposed voltage (which relates to and is greater than the ripple on the feedback voltage) to enable the primary controller to control the switching on of the primary side of the power converter. Therefore, when the output voltage is lower than the target voltage (related to the reference voltage), the operating frequency of the power switch on the primary side of the power converter will not rapidly increase in a short period of time because the superimposed voltage is greater than the ripple on the feedback voltage. Thus, compared to the prior art, because the secondary controller disclosed in this invention uses the superimposed voltage to enable the primary controller to control the switching on of the primary side of the power converter, rather than directly using the feedback voltage, the ripple on the feedback voltage will not appear in clusters when the output voltage on the secondary side of the power converter is lower than the target voltage, and the power converter will not exhibit audible noise.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A secondary controller applied to the secondary side of a power converter, characterized in that... Include: A gate control signal generation circuit is used to generate a gate control signal and to generate an injection signal based on the gate control signal. and A control signal generation circuit, coupled to the output terminal of the secondary side of the power converter and the gate control signal generation circuit, is used to generate a gate pulse control signal when an overlay voltage is less than a reference voltage, wherein the overlay voltage is related to the output voltage of the power converter and the injection signal. The gate control signal generation circuit is further used to generate a gate pulse signal according to the gate pulse control signal, and the gate pulse signal is used to turn on the primary side of the power converter.

2. The secondary controller as described in claim 1, characterized in that... The control signal generation circuit is further configured to generate a short-circuit control signal to a short-circuit winding switch after the gate control signal when the superimposed voltage is greater than a reference voltage, so that the short-circuit winding switch is turned on according to the short-circuit control signal.

3. The secondary controller as described in claim 2, characterized in that... There is a predetermined time between the gate control signal and the short-circuit control signal.

4. The secondary controller as described in claim 2, characterized in that... When the superimposed voltage is less than the reference voltage, the control signal generation circuit is further used to shut down the short-circuit control signal.

5. The secondary controller as described in claim 2, characterized in that... The short-circuit winding switch is coupled to the secondary winding of the power converter.

6. The secondary controller as described in claim 2, characterized in that... During the period when the short-circuit winding switch is open, the primary side of the power converter is closed.

7. The secondary controller of claim 1, wherein a synchronous switch on the secondary side of the power converter is turned on according to the gate pulse signal, and during the activation of the gate pulse signal, the change in the secondary side voltage of the power converter caused by the turning on of the synchronous switch is coupled to the primary side of the power converter through the secondary winding and the primary auxiliary winding of the power converter, thereby turning on the primary side of the power converter.

8. The secondary controller as described in claim 1, characterized in that... The gate control signal generation circuit further generates the gate control signal based on the secondary side voltage of the power converter, and a synchronous switch on the secondary side of the power converter is turned on according to the gate control signal.

9. The secondary controller as described in claim 8, characterized in that... When the synchronous switch is turned on according to the gate control signal, the width of the injected signal and the discharge time of the secondary side of the power converter are in a predetermined ratio.

10. The secondary controller as described in claim 1, characterized in that... The power converter is a flyback power converter.

11. A method for operating a secondary controller applied to the secondary side of a power converter, the secondary controller comprising a control signal generation circuit and a gate control signal generation circuit, characterized in that... Include: The gate control signal generation circuit generates a gate control signal and generates an injection signal based on the gate control signal. The control signal generation circuit generates a superimposed voltage based on the output voltage of the power converter and the injected signal; When the superimposed voltage is greater than a reference voltage, the control signal generating circuit generates a short-circuit control signal after the gate control signal to a short-circuit winding switch so that the short-circuit winding switch is turned on according to the short-circuit control signal. When the superimposed voltage is less than the reference voltage, the control signal generation circuit generates a gate pulse control signal; and The gate control signal generation circuit generates a gate pulse signal according to the gate pulse control signal, wherein the gate pulse signal is used to turn on the primary side of the power converter.

12. The operating method as described in claim 11, characterized in that... During the period when the short-circuit winding switch is open, the primary side of the power converter is closed.

13. The operating method as described in claim 11, characterized in that... The gate pulse signal is used to turn on the primary side of the power converter, including: A synchronous switch on the secondary side of the power converter is turned on according to the gate pulse signal; and During the activation of the gate pulse signal, the change in the secondary side voltage of the power converter caused by the activation of the synchronous switch is coupled to the primary side of the power converter through the secondary winding and the primary auxiliary winding, thereby turning on the primary side of the power converter.

14. The operating method as described in claim 11, characterized in that... There is a predetermined time between the gate control signal and the short-circuit control signal.

15. The operating method as described in claim 11, characterized in that... When the superimposed voltage is less than the reference voltage, the control signal generation circuit is further used to shut down the short-circuit control signal.

16. The operating method as described in claim 11, characterized in that... During the power converter's secondary side turn-on period, the gate control signal generation circuit generates the gate control signal based on the secondary side voltage of the power converter's secondary side, and a synchronous switch on the power converter's secondary side turns on based on the gate control signal.

17. The operating method as described in claim 16, characterized in that... When the synchronous switch is turned on according to the gate control signal, the width of the injected signal and the discharge time of the secondary side of the power converter are in a predetermined ratio.

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