Power converter and feedback control method thereof

Abstract

The invention provides a power converter and a feedback control method thereof. The power converter comprises a primary side circuit, a primary side controller, a primary side winding circuit, a secondary side circuit, a secondary side controller and a first optical coupler. The primary side controller generates a first control signal according to the first feedback signal, and the primary side winding circuit provides a second feedback signal. The secondary side controller generates a first feedback signal according to the DC output signal, and the first optical coupler provides the first feedback signal to the primary side controller. The primary side controller provides a first control signal according to the first feedback signal to control the primary side circuit, and when the primary side controller knows that the output current of the power converter is lower than the current threshold value, the primary side controller generates the first control signal according to the second feedback signal.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Taiwan Patent Application No. 112137947 filed on October 3, 2023, which is incorporated herein by reference for all purposes as if fully set forth herein. Technical Field

[0003] The present invention relates to a power converter and a feedback control method thereof, and in particular to a power converter with loss reduction control and a feedback control method thereof. Background Art

[0004] With the rapid development of the information industry, power converters have played an indispensable role. Power converters generally use isolated converters to electrically isolate the input and output ends of the power converter to prevent abnormal input power from affecting the load coupled to the back end. In the basic circuit of the power converter, in response to the development of high-efficiency and high-power (wattage), many performance improvement circuits have been derived, especially in today's electronic circuit development, which pays more and more attention to power consumption and efficiency. If the power converter is to further improve its performance, it is necessary to further reduce the power consumption of the power converter.

[0005] However, in order to reduce the loss of the power converter, the conventional power converter usually uses a method of reducing the operating frequency of the primary side controller under light load or no load conditions, or even enters the burst mode to reduce the operating period of the primary side controller as much as possible. However, the above operation method still needs to confirm whether the output power meets the requirements by detecting the feedback of the secondary side, so the circuits, controllers and other components on the secondary side are still forced to operate continuously to avoid the failure to control the output power well due to the failure to continuously detect the output power.

[0006] However, in the technical field of power conversion, it is increasingly valued that power converters must have the characteristics of energy saving and low consumption. Therefore, how to design a power converter and its feedback control method to reduce the power consumption of the power converter when operating at light load or no load by changing the feedback method of the power converter is a major topic that the present invention intends to study. Summary of the invention

[0007] In order to solve the above problems, one aspect of the present invention provides a power converter with loss reduction control to overcome the problems of the prior art.

[0008] Therefore, the power converter of the present invention includes a primary side circuit, a primary side controller, a primary side winding circuit, a secondary side circuit, a secondary side controller and a first optical coupler. The primary side controller is coupled to the primary side circuit and generates a first control signal according to a first feedback signal. The primary side winding circuit is coupled to the primary side controller and provides a second feedback signal. The secondary side controller is coupled to the secondary side circuit and generates a first feedback signal according to a DC output signal. The first optical coupler couples the secondary side controller and the primary side controller to provide the first feedback signal to the primary side controller. The primary side controller provides a first control signal to control the primary side circuit according to the first feedback signal, and when the primary side controller knows that the output current of the power converter is lower than the current threshold, the primary side controller generates a first control signal according to the second feedback signal.

[0009] In order to solve the above problems, the present invention further provides a feedback control method of a power converter to overcome the problems of the prior art.

[0010] Therefore, the power converter of the present invention includes a primary side circuit, a primary side controller, a primary side winding circuit, a secondary side controller and a first optical coupler, and the feedback control method includes the following steps: (a) The secondary side controller generates a first feedback signal according to the DC output signal of the power converter, and provides the first feedback signal to the primary side controller through the first optical coupler. The primary side winding circuit provides a second feedback signal corresponding to the DC output signal to the primary side controller. The primary side controller generates a first control signal according to the first feedback signal to control the primary side circuit through the first control signal. When the primary side controller knows that the output current of the power converter is lower than the current threshold, the first control signal is generated according to the second feedback signal.

[0011] The main purpose and effect of the present invention are:

[0012] When the primary side controller knows that the output current of the power converter is lower than the current threshold, the primary side controller receives the second feedback signal corresponding to the auxiliary voltage from the primary side winding circuit, so that the primary side controller generates a first control signal for controlling the primary side circuit based on the second feedback signal, thereby maintaining the stability of the output power. In this way, the power converter can reduce the power consumption of the power converter by changing the feedback method.

[0013] In order to further understand the technologies, means and effects adopted by the present application to achieve the intended purpose, please refer to the following detailed description and drawings of the present application. It is believed that the purpose, characteristics and features of the present application can be deeply and specifically understood thereby. However, the drawings are only provided for reference and illustration and are not intended to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1AA circuit block diagram of a power converter with loss reduction control according to the present invention;

[0015] Figure 1B A detailed circuit block diagram of a power converter with loss reduction control according to the present invention;

[0016] Figure 2A A circuit block diagram of a first embodiment of feedback control of a power converter according to the present invention;

[0017] Figure 2B A signal waveform diagram of a first embodiment of feedback control of a power converter of the present invention;

[0018] Figure 3A A circuit block diagram of a second embodiment of the feedback control of the power converter of the present invention;

[0019] Figure 3B A signal waveform diagram of a second embodiment of the feedback control of the power converter of the present invention;

[0020] Figure 4A A circuit block diagram of a third embodiment of the feedback control of a power converter according to the present invention;

[0021] Figure 4B A signal waveform diagram of a third embodiment of the feedback control of the power converter of the present invention;

[0022] Figure 5A A circuit block diagram of a fourth embodiment of the feedback control of a power converter according to the present invention;

[0023] Figure 5B A signal waveform diagram of a fourth embodiment of the feedback control of the power converter of the present invention;

[0024] Fig. 6A A circuit block diagram of a fifth embodiment of the feedback control of the power converter of the present invention;

[0025] Figure 6B A signal waveform diagram of a fifth embodiment of the feedback control of the power converter of the present invention;

[0026] Figure 7 A circuit block diagram of a sixth embodiment of the feedback control of a power converter according to the present invention;

[0027] Figure 8 is a circuit block diagram of a power converter of a sixth embodiment of the voltage stabilizing circuit of the present invention; and

[0028] Fig. 9 The figure is a flow chart of the feedback control method of the power converter of the present invention.

[0029] Wherein, the reference numerals are:

[0030] 100-Power Converter

[0031] 1-Primary side controller

[0032] FBp-primary side feedback terminal

[0033] VDD-power supply terminal

[0034] 2-Primary side circuit

[0035] 22-AC to DC circuit

[0036] SW-Power Switch

[0037] 24-Primary coil

[0038] 3-Primary winding circuit

[0039] 32-Auxiliary winding

[0040] R1, R2-voltage divider circuit

[0041] D-Diode

[0042] 4- Secondary side circuit

[0043] 42-Secondary coil

[0044] 44-Rectifier filter circuit

[0045] 5-Secondary side controller

[0046] CC / ID-pin

[0047] FBs-Signal Receiver

[0048] 6-First optical coupler

[0049] 6A-Photocoupler Diode

[0050] 72-Current detection circuit

[0051] 74-Cycle Detection Circuit

[0052] 76-Frequency detection circuit

[0053] 78-Pulse detection circuit

[0054] 8- Second optical coupler

[0055] 9- Voltage stabilization circuit

[0056] 200-load

[0057] Pin-Input Power

[0058] Po-output power

[0059] Vaux - auxiliary voltage

[0060] Vs - Secondary side voltage

[0061] Ic - Current

[0062] Io - output current

[0063] Sfb1-First feedback signal

[0064] Sfb2-second feedback signal

[0065] Sc1-First control signal

[0066] Sc2-Second control signal

[0067] So-DC output signal

[0068] Si-Current Signal

[0069] Se-External signal

[0070] Sd-periodic signal

[0071] Sf-Frequency Signal

[0072] Sp-Pulse Signal

[0073] Ss-Detection Signal

[0074] (S100)~(S400)…steps. DETAILED DESCRIPTION

[0075] The technical content and detailed description of this application are described below with reference to the accompanying drawings:

[0076] See also Figure 1AThe circuit block diagram of the power converter with loss reduction control of the present invention is shown. The power converter 100 receives an input power Pin and is coupled to a load 200 to convert the input power Pin into an output power Po to power the load 200. The power converter 100 can be an isolated conversion circuit (for example, but not limited to a flyback type, a forward type, etc.), and the power converter 100 includes a primary side controller 1, a primary side circuit 2, a primary side winding circuit 3, a secondary side circuit 4, a secondary side controller 5 and a first optical coupler 6. The primary side controller 1 can receive the input power Pin by, for example, but not limited to, coupling to a pre-stage circuit (not shown) or coupling to an input source. The primary side controller 1 is coupled to the primary side circuit 2, and generates a first control signal Sc1 according to a first feedback signal Sfb1 to control the primary side circuit 2. One end of the secondary side circuit 4 is coupled to the primary side circuit 2, and the other end is coupled to the load 200 to provide an output power Po to power the load 200. The secondary side controller 5 is coupled to the secondary side circuit 4, and generates a first feedback signal Sfb1 according to the DC output signal So corresponding to the output power supply Po. The first optical coupler 6 couples the secondary side controller 5 and the primary side controller 1 to provide the first feedback signal Sfb1 to the primary side controller 1. The primary side winding circuit 3 is coupled to the primary side controller 1, and provides an auxiliary voltage Vaux to power the primary side controller 1. It is worth mentioning that in one embodiment, the "power supply" described herein may refer to at least one of voltage, current and power. For example but not limited to, the "output power supply Po" may refer to at least one of output voltage, output current and output power. Therefore, the "DC output signal So corresponding to the output power supply Po" can be expressed as the DC output signal So may correspond to at least one of the output voltage, output current and output power, and so on, which will not be repeated here.

[0077] When the power converter 100 receives the input power Pin, the primary side controller 1 performs high voltage startup based on the input power Pin, and after the high voltage startup, starts to provide the first control signal Sc1 to the primary side circuit 2, so that the primary side circuit 2 converts the energy of the input power Pin. Then, the primary side circuit 2 couples the converted energy to the primary side winding circuit 3, so that the primary side winding circuit 3 provides the auxiliary voltage Vaux to the primary side controller 1 to complete the startup of the primary side controller 1 (that is, the power of the primary side controller 1 is supplied by the auxiliary voltage Vaux, and no longer by the input power Pin). The primary side circuit 2 also couples the converted energy to the secondary side circuit 4, and the secondary side controller 5 operates by receiving the energy coupled to the secondary side circuit 4, and converts the energy coupled to the secondary side circuit 4 into the output power Po by controlling the secondary side circuit 4. The secondary side controller 5 also generates a first feedback signal Sfb1 according to the DC output signal So corresponding to the output power supply Po, and transmits the first feedback signal Sfb1 to the primary side controller 1 through the first optical coupler 6, so that the primary side controller 1 adjusts and controls the first control signal Sc1 of the primary side circuit 2 based on the first feedback signal Sfb1, so as to control the power converter 100 to provide a stable output power supply Po by adjusting the first control signal Sc1.

[0078] For example, assuming that the output power supply Po changes from 5V, 3A to 5V, 1A, the energy transmitted from the primary side circuit 2 to the secondary side circuit 4 is excessive, and the current Ic flowing through the optocoupler diode 6A of the first optocoupler 6 becomes larger, which can make the optocoupler diode 6A emit more light, so that the voltage received by the primary side controller 1 is pulled down, so as to notify the primary side controller 1 to reduce the energy transmitted to the secondary side circuit 4. On the contrary, when the output power supply Po changes from 5V, 1A to 5V, 3A, the energy transmitted from the primary side circuit 2 to the secondary side is insufficient, and the current Ic flowing through the optocoupler diode 6A becomes smaller, which can make the optocoupler diode 6A emit less light, so that the voltage received by the primary side controller 1 is pulled down, so as to notify the primary side controller 1 to increase the energy transmitted to the secondary side circuit 4. Therefore, when the power converter 100 receives the input power supply Pin, the power converter 100 starts the primary side controller 1 and the secondary side controller 5 to perform conventional feedback control and provide conventional output power supply Po.

[0079] In order to reduce the power consumption of the power converter 100 when it is operated at light load or no load, the present invention changes the feedback mode of the power converter 100 when it is operated at light load. Specifically, after the power converter 100 receives the input power Pin and the primary side controller 1 and the secondary side controller 5 are normally started, the secondary side controller 5 will provide the first feedback signal Sfb1 to the primary side controller 1 at least once or for a period of one hour (for example but not limited to, 3 to 5 μs) (i.e., conventional feedback control). After that, when the primary side controller 1 knows that the output current Io of the power converter 100 is lower than the current threshold, it means that the power converter 100 is operated at light load or no load, and the power converter 100 can reduce the power consumption of the power converter 100 by changing the feedback mode. Since the auxiliary voltage Vaux has a linear relationship with the output power Po, when the power converter 100 operates at a light load or no load, the primary side controller 1 can receive the second feedback signal Sfb2 corresponding to the auxiliary voltage Vaux from the primary side winding circuit 3, so that the primary side controller 1 generates the first control signal Sc1 based on the second feedback signal Sfb2. It is worth mentioning that in one embodiment, the present invention may include a plurality of feedback control methods for the primary side controller 1 to know that the power converter 100 operates at a light load or no load, which will be further described later and will not be repeated here.

[0080] On the other hand, when the output current Io is lower than the current threshold, the secondary side controller 5 can selectively enter a dormant state or a shutdown state. In this way, the first optical coupler 6 can be disabled to avoid the power consumption of the first optical coupler 6 when the power converter 100 operates at a light load or no load, and at the same time, the power consumption of the secondary side controller 5 when the power converter 100 operates at a light load or no load can be saved. Among them, the dormant state refers to the secondary side controller 5 disabling unnecessary pins (for example, but not limited to, the pin coupled to the first optical coupler 6, the pin coupled to the secondary side circuit 4 and receiving the DC output signal So, and / or the pin for detecting voltage and current signals, etc.). The shutdown state refers to the secondary side controller 5 only having the pins for receiving power and the switch (not shown) that can provide power to the secondary side controller 5 by turning on / off. In addition, all components inside the secondary side controller 5 do not operate, causing the secondary side controller 5 to be temporarily shut down.

[0081] It is worth mentioning that, in one embodiment, when the primary side controller 1 receives the second feedback signal Sfb2 instead, the primary side controller 1 can disable the pin coupled to the first optical coupler 6 to save the power consumption of the primary side controller 1. In addition, in one embodiment, when the power converter 100 is not operating at a light load or no load, the primary side controller 1 can selectively enable or disable the pin receiving the second feedback signal Sfb2. When the pin receiving the second feedback signal Sfb2 is enabled, the primary side controller 1 can monitor the output power Po through the second feedback signal Sfb2. Conversely, when the pin receiving the second feedback signal Sfb2 is disabled, the power consumption of the primary side controller 1 can be saved.

[0082] See also Figure 1B The detailed circuit block diagram of the power converter with loss reduction control of the present invention is further combined with reference to Figure 1A . The primary side circuit 2 includes an AC-to-DC circuit 22 and a primary side coil 24, and the secondary side circuit 4 includes a secondary side coil 42 and a rectifier filter circuit 44. The primary side coil 24 is coupled to the secondary side coil 42 to form an isolation transformer. The AC-to-DC circuit 22 receives an input power source Pin and is coupled to the primary side coil 24. The AC-to-DC circuit 22 includes at least one power switch SW, and the primary side controller 1 controls the power switch SW through a first control signal Sc1 to convert the input power source Pin, and provides the converted energy through the primary side coil 24 by coupling. The secondary side coil 42 is coupled to the primary side coil 24, and the rectifier filter circuit 44 couples the secondary side coil 42 and the secondary side controller 5. The secondary side controller 5 rectifies and filters the energy coupled from the primary side coil 24 to the secondary side coil 42 by controlling the rectifier filter circuit 44 to generate an output power source Po.

[0083] The primary side winding circuit 3 includes an auxiliary winding 32, a voltage divider circuit R1, R2 and a diode D, and the auxiliary winding 32 is coupled to the primary side coil 24. The voltage divider circuits R1 and R2 are connected in parallel to the auxiliary winding 32, and include a first resistor R1 and a second resistor R2 connected in series. The primary side feedback terminal FBp of the primary side controller 1 is coupled between the first resistor R1 and the second resistor R2, and when the auxiliary winding 32 receives the auxiliary voltage Vaux coupled from the primary side coil 24, the voltage divider circuits R1 and R2 divide the auxiliary voltage Vaux and generate a second feedback signal Sfb2 at a node between the first resistor R1 and the second resistor R2, so as to provide the second feedback signal Sfb2 to the primary side feedback terminal FBp of the primary side controller 1. The diode D is coupled to the first resistor R1 and the power supply terminal VDD of the primary side controller 1, and the auxiliary voltage Vaux is reverse biased by the diode D to prevent the negative voltage from being transmitted to the power supply terminal VDD of the primary side controller 1.

[0084] See also Figure 2AA circuit block diagram of a first embodiment of feedback control of a power converter according to the present invention, Figure 2B The signal waveform diagram of the first embodiment of the feedback control of the power converter of the present invention is further combined with Figure 1A to Figure 1B .exist Figure 2A In the embodiment, the power converter 100 further includes a current detection circuit 72, and the current detection circuit 72 is coupled to the rectifier filter circuit 44 and the secondary side controller 5. When the rectifier filter circuit 44 provides the output power Po, the current detection circuit 72 detects the output current Io on the path between the rectifier filter circuit 44 and the load 200 and provides a current signal Si accordingly. The secondary side controller 5 receives the current signal Si and determines whether the output current Io is lower than the current threshold according to the current signal Si.

[0085] When the secondary-side controller 5 determines that the output current Io is lower than the current threshold according to the current signal Si, the secondary-side controller 5 adjusts, for example but not limited to, the current Ic flowing through the optocoupler diode 6A to transmit, for example but not limited to, Figure 2B The primary side controller 1 is notified by the first feedback signal Sfb1 of the continuous pulse (or specific signal) shown. The secondary side controller 5 enters the sleep state or the shutdown state after transmitting the first feedback signal Sfb1 of the continuous pulse (or specific signal), and disables the first optical coupler 6 at the same time. When the primary side controller 1 receives the first feedback signal Sfb1 of the continuous pulse (or specific signal), the secondary side controller 5 enters the sleep state or the shutdown state, and disables the first optical coupler 6 at the same time. Figure 2B When the first feedback signal Sfb1 of the continuous pulse (or specific signal) is received, the primary-side controller 1 receives the second feedback signal Sfb2 from the primary-side feedback terminal FBp to adjust the first control signal Sc1 according to the second feedback signal Sfb2.

[0086] On the contrary, when the secondary side controller 5 determines that the output current Io is not lower than the current threshold value, or increases from lower than the current threshold value to higher than the current threshold value according to the current signal Si, the secondary side controller 5 and the first optical coupler 6 enter the enabled state, and provide the first feedback signal Sfb1 accordingly according to the output power supply Po, so that the primary side controller 1 can adjust the first control signal Sc1 based on the first feedback signal Sfb1. When the secondary side controller 5 returns to the enabled state from the sleep state or the shutdown state, the secondary side controller 5 can also transmit a signal similar to Figure 2B The first feedback signal Sfb1 of continuous pulses (or specific signals) notifies the primary-side controller 1, so that the primary-side controller 1 performs corresponding control (for example but not limited to, disabling the primary-side feedback terminal FBp).

[0087] See also Figure 3A A circuit block diagram of a second embodiment of the feedback control of the power converter of the present invention, Figure 3B The signal waveform diagram of the second embodiment of the feedback control of the power converter of the present invention is shown in FIG. Figure 1A to Figure 2B .exist Figure 3A In the embodiment, an external device (such as but not limited to, the load 200, the system end, or other external or upper device) provides an external signal Se to the secondary side controller 5 (such as but not limited to, provided to the CC / ID pin of the secondary side controller 5) to notify the secondary side controller 5 to enter the low loss mode. Then, the secondary side controller 5 performs the following steps: Figure 3B The first feedback signal Sfb1 of the continuous pulse (or specific signal) shown in the figure notifies the primary side controller 1, so that the primary side controller 1 receives the second feedback signal Sfb2 from the primary side feedback terminal FBp instead. It is worth mentioning that the subsequent operation mode and signal waveform of the primary side controller 1 and the secondary side controller 5 can be similar to Figure 2A to Figure 2B , I will not elaborate on it here.

[0088] See also Figure 4A A circuit block diagram of a third embodiment of the feedback control of the power converter of the present invention, Figure 4B The signal waveform diagram of the third embodiment of the feedback control of the power converter of the present invention is shown in FIG. Figure 1A to Figure 3B .exist Figure 4A In the power converter 100, the power converter 100 further includes a cycle detection circuit 74, and the cycle detection circuit 74 is coupled between the secondary side coil 42, the rectifier filter circuit 44 and the secondary side controller 5. When the secondary side coil 42 receives energy coupled from the primary side coil 24, the cycle detection circuit 74 detects the voltage conduction period of the secondary side voltage Vs of the secondary side coil 42 and provides a cycle signal Sd accordingly. The secondary side controller 5 receives the cycle signal Sd, and determines whether the output current Io is lower than the current threshold based on the cycle signal Sd. Furthermore, in some power converter secondary 100, the voltage conduction period of the secondary side voltage Vs of the secondary side coil 42 and the magnitude of the output current Io may present a linear relationship. When the output current Io is larger, the voltage conduction period of the secondary side voltage Vs of the secondary side coil 42 is larger, and vice versa. Therefore, the secondary side controller 5 can determine whether the output current Io is lower than the current threshold based on the cycle signal Sd. It is worth mentioning that Figure 4A to Figure 4B The subsequent operation mode and signal waveform of the primary side controller 1 and the secondary side controller 5 may be similar to Figure 2A to Figure 2B , I will not elaborate on it here.

[0089] See also Figure 5A A circuit block diagram of a fourth embodiment of the feedback control of the power converter of the present invention, Figure 5B The signal waveform diagram of the fourth embodiment of the feedback control of the power converter of the present invention is further combined with Figure 1A to Figure 4B . Figure 5A to Figure 5B and Figure 4A and Figure 4B The difference is that Figure 4AThe period detection circuit 74 can be replaced by a frequency detection circuit 76. The frequency detection circuit 76 detects the voltage switching frequency of the secondary side voltage Vs of the secondary side coil 42 and provides a frequency signal Sf accordingly. The secondary side controller 5 receives the frequency signal Sf, and determines whether the output current Io is lower than the current threshold value based on the frequency signal Sf. Furthermore, in some power converter secondary 100, the voltage switching frequency of the secondary side voltage Vs of the secondary side coil 42 and the magnitude of the output current Io may present a linear relationship. When the output current Io is larger, the voltage switching frequency of the secondary side voltage Vs of the secondary side coil 42 is larger, and vice versa. Therefore, the secondary side controller 5 can determine whether the output current Io is lower than the current threshold value based on the frequency signal Sf. It is worth mentioning that Figure 5A to Figure 5B The operation mode and signal waveform of the primary side controller 1 and the secondary side controller 5 may be similar to Figure 2A to Figure 2B , I will not elaborate on it here.

[0090] See also Fig. 6A A circuit block diagram of a fifth embodiment of the feedback control of the power converter of the present invention, Figure 6B The signal waveform diagram of the fifth embodiment of the feedback control of the power converter of the present invention is shown in FIG. Figure 1A to Figure 5B .exist Fig. 6A In the embodiment, the power converter 100 further includes a pulse detection circuit 78, and the pulse detection circuit 78 is coupled between the secondary side coil 42, the rectifier filter circuit 44 and the secondary side controller 5. The power switch SW can be coupled between the primary side coil 24 and the primary side controller 1, for example but not limited to. When the primary side controller 1 knows that the output current Io is lower than the current threshold through the voltage level of the first feedback signal Sfb1 or the second feedback signal Sfb2, it means that the power converter 100 is operating at a light load or no load, and the power converter 100 can reduce the power consumption of the power converter 100 by changing the feedback method.

[0091] Therefore, the primary-side controller 1 controls the power switch SW to generate the following signal through the first control signal Sc1: Figure 6BThe specific pulse shown in the figure is used, and the primary side controller 1 receives the second feedback signal Sfb2 from the primary side feedback terminal FBp to generate the first control signal Sc1. Furthermore, the primary side controller 1 can add the pulse signal Sp to the first control signal Sc1 to control the power switch SW to generate a specific pulse with a specific frequency or a specific period. The specific frequency and the specific period are different from the operating frequency and the operating period of the first control signal Sc1, so that the operating frequency and the operating period of the first control signal Sc1 change within a certain period of time (for example, but not limited to 1μs). The pulse detection circuit 78 receives the secondary side voltage Vs corresponding to the first control signal Sc1 through the secondary side coil 42 to provide a detection signal Ss accordingly according to the specific pulse. After receiving the detection signal Ss, the secondary side controller 5 enters a sleep state or a shutdown state, and at the same time disables the first optocoupler 6.

[0092] On the contrary, when the primary-side controller 1 determines through the voltage level of the first feedback signal Sfb1 or the second feedback signal Sfb2 that the output current Io is not lower than the current threshold, or increases from lower than the current threshold to higher than the current threshold, the primary-side controller 1 can control the power switch SW through the first control signal Sc1 to generate a current similar to Figure 6B The specific pulse shown causes the secondary-side controller 5 to enter an enabled state after receiving the corresponding detection signal Ss and enable the first optical coupler 6 , and the primary-side controller 1 receives the first feedback signal Sfb1 provided by the first optical coupler 6 .

[0093] See also Figure 7 The circuit block diagram of the sixth embodiment of the feedback control of the power converter of the present invention is further combined with Figure 1A to Figure 6B .exist Figure 7 In the embodiment, the power converter 100 further includes a second optical coupler 8, and the second optical coupler 8 is coupled to the primary side controller 1 and the secondary side controller 5. When the primary side controller 1 knows that the output current Io is lower than the current threshold through the voltage level of the first feedback signal Sfb1 or the second feedback signal Sfb2, it means that the power converter 100 operates at a light load or no load, and the power converter 100 can reduce the power consumption of the power converter 100 by changing the feedback method.

[0094] Therefore, the primary side controller 1 provides the second control signal Sc2 to the second optical coupler 8 (for example but not limited to controlling the current flowing through the optical coupling diode of the second optical coupler 8 to be 0), and the primary side controller 1 receives the second feedback signal Sfb2 from the primary side feedback terminal FBp to generate the first control signal Sc1. The second optical coupler 8 couples the second control signal Sc2 to the signal receiving terminal FBs of the secondary side controller 5, and when the signal receiving terminal FBs receives the second control signal Sc2, it enters a dormant state or a shutdown state, and at the same time disables the first optical coupler 6. Taking the current flowing through the optical coupling diode of the second optical coupler 8 as 0 as an example, the voltage received by the signal receiving terminal FBs is at a high level, causing the secondary side controller 5 to enter a dormant state or a shutdown state accordingly.

[0095] On the contrary, when the primary-side controller 1 determines that the output current Io is not lower than the current threshold value, or increases from lower than the current threshold value to higher than the current threshold value through the voltage level of the first feedback signal Sfb1 or the second feedback signal Sfb2, the primary-side controller 1 can provide the second control signal Sc2 to the signal receiving terminal FBs of the secondary-side controller 5 through the second optical coupler 8, so that the secondary-side controller 5 enters the enabled state and enables the first optical coupler 6, and the primary-side controller 1 receives the first feedback signal Sfb1 provided by the first optical coupler 6 instead. It is worth mentioning that in one embodiment, although the signals at the input and output ends of the first optical coupler 6 are not the same (for example, Figure 2B The current Ic and the first feedback signal Sfb1 are shown in the figure, but these two are relatively fixed signals, so if not specifically specified in the present invention, they can be regarded as the same signal. For example, but not limited to, in the present invention, the description of "the secondary side controller 5 provides the first feedback signal Sfb" and "the first optical coupler 6 couples the first feedback signal Sfb1 to the primary side controller 1", the first feedback signal Sfb can be regarded as the same signal, and so on. On the other hand, the second control signal Sc2 received / provided by the second optical coupler 8 is also the same, and will not be repeated here.

[0096] See also Figure 8 FIG. 1 is a circuit block diagram of a voltage stabilizing circuit of the present invention applied to a power converter of a sixth embodiment. Figure 2A to Figure 7 . Figure 8 The embodiment can preferably be applied to Figure 7 A sixth embodiment of the power converter 100 is provided. Figure 8In the embodiment, the secondary side controller 5 can be formed by a voltage regulator circuit 9, such as but not limited to, a TL431 voltage regulator and specific passive circuit elements (i.e., resistors, capacitors, etc.), which can mainly be a compensation circuit of Type I to Type III. The negative electrode of the voltage regulator circuit 9 is the signal receiving terminal FBs, and is coupled to the second optical coupler 8. Therefore, when the second optical coupler 8 couples the second control signal Sc2 to the signal receiving terminal FBs, so that the voltage received by the signal receiving terminal FBs is at a high level, the voltage regulator circuit 9 fails and causes the secondary side controller 5 to be in a closed state, and at the same time disables the first optical coupler 6. On the contrary, when the second optical coupler 8 couples the second control signal Sc2 to the signal receiving terminal FBs, so that the voltage received by the signal receiving terminal FBs is not at a high level, the voltage regulator circuit 9 is in an enabled state, so that the current Ic flows through the optical coupler diode 6A of the first optical coupler 6 to enable the first optical coupler 6. At this time, the primary-side controller 1 receives the first feedback signal Sfb1 provided by the first optical coupler 6 instead.

[0097] It is worth mentioning that, in one embodiment, Figure 2A to Figure 8 The features of can be applied to each other. For example, Figure 2A The secondary side controller 5 of the power converter 100 may be applied Figure 7-8 The second optical coupler 8 and the voltage regulator circuit 9 of the embodiment enable the current signal Si to cause the TL431 voltage regulator to fail when the secondary side controller 5 determines that the output current Io is lower than the current threshold through the current signal Si, so as to notify the primary side controller 1 through the first optical coupler 6, and when the primary side controller 1 determines that the output current Io is not lower than the current threshold through the voltage level of the second feedback signal Sfb2, the primary side controller 1 activates the voltage regulator circuit 9 through the second optical coupler 8. By analogy with the above exemplary example, it will not be repeated here.

[0098] See also Fig. 9 is a flow chart of the feedback control method of the power converter of the present invention, and further reference is made to Figure 1A to Figure 8. The feedback control method of the present invention is mainly to reduce the power consumption of the power converter 100 when operating at light load or no load. Therefore, when the power converter 100 of the present invention operates at light load, the feedback mode of the power converter 100 will be changed. Before entering the feedback control method, the primary side controller 1 and the secondary side controller 5 need to be started first. When the power converter 100 receives the input power Pin, the primary side controller 1 performs high voltage startup based on the input power Pin, and after the high voltage startup, it starts to provide the first control signal Sc1 to the primary side circuit 2, so that the primary side circuit 2 converts the energy of the input power Pin. Then, the primary side circuit 2 couples the converted energy to the primary side winding circuit 3, so that the primary side winding circuit 3 provides the auxiliary voltage Vaux to the primary side controller 1 to complete the startup of the primary side controller 1. The primary side circuit 2 also couples the converted energy to the secondary side circuit 4, and the secondary side controller 5 operates by receiving the energy coupled to the secondary side circuit 4, and converts the energy coupled to the secondary side circuit 4 into the output power Po by controlling the secondary side circuit 4. Thereby, the power converter 100 can start to operate the feedback control method based on the magnitude of the output current Io.

[0099] Then, the secondary side controller generates a first feedback signal according to the DC output signal of the power converter, and provides the first feedback signal to the primary side controller through the first optical coupler (S100). After the power converter 100 receives the input power Pin and the primary side controller 1 and the secondary side controller 5 are normally started, the secondary side controller 5 will provide the first feedback signal Sfb1 to the primary side controller 1 at least once or for a period of one hour (for example but not limited to, 3 to 5 μs) (i.e., conventional feedback control).

[0100] Then, the primary side winding circuit provides a second feedback signal corresponding to the DC output signal to the primary side controller (S200). Since the auxiliary voltage Vaux has a linear relationship with the output power supply Po, and the DC output signal So also has a corresponding relationship with the output power supply Po, the primary side controller 1 can receive the second feedback signal Sfb2 corresponding to the DC output signal So from the primary side winding circuit 3, so that the primary side controller 1 can use the second feedback signal Sfb2 to control the power converter 100 at any time. Moreover, when the second feedback signal Sfb2 is not needed to control the power converter 100, the output power supply Po can also be monitored by the second feedback signal Sfb2, or when the second feedback signal Sfb2 is not needed to control the power converter 100, the pin receiving the second feedback signal Sfb2 can also be disabled.

[0101] Then, the primary side controller generates a first control signal according to the first feedback signal to control the primary side circuit through the first control signal (S300). The primary side controller 1 adjusts the first control signal Sc1 of the primary side circuit 2 based on the first feedback signal Sfb1 to control the power converter 100 to provide a stable output power Po by adjusting the first control signal Sc1.

[0102] After this, the power converter 100 can selectively enter the low-loss mode according to the size of the output current Io. Therefore, when the primary side controller knows that the output current of the power converter is lower than the current threshold, it generates a first control signal (S400) according to the second feedback signal. When the primary side controller 1 knows that the output current Io of the power converter 100 is lower than the current threshold, it means that the power converter 100 is operating at a light load or no load. Therefore, the primary side controller 1 can receive the second feedback signal Sfb2 corresponding to the auxiliary voltage Vaux from the primary side winding circuit 3, so that the primary side controller 1 generates a first control signal Sc1 based on the second feedback signal Sfb2. In this way, devices and circuits that are not in operation can be disabled or put into sleep mode (for example, but not limited to, the secondary side controller 5 and the first optocoupler 6) to save power consumption when the power converter 100 is operating at a light load. It is worth mentioning that in one embodiment, the detailed operating steps and methods of the power converter 100 can be referred to in conjunction with. Figure 1A to Figure 8 , I will not elaborate on it here.

[0103] However, the above is only a preferred embodiment of the present application, and should not limit the scope of implementation of the present application, that is, all equivalent changes and modifications made according to the present application should still fall within the scope of the patent coverage of the present application. The present application may also have other embodiments, and those skilled in the art may make various corresponding changes and deformations according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and deformations should fall within the scope of protection of the claims attached to the present application.

Claims

1. A power converter, characterized in that: include: a primary side circuit; a primary-side controller coupled to the primary-side circuit and generating a first control signal according to a first feedback signal; a primary-side winding circuit coupled to the primary-side controller and providing a second feedback signal; A secondary side circuit; a secondary-side controller coupled to the secondary-side circuit and generating the first feedback signal according to a DC output signal; as well as a first optical coupler coupling the secondary-side controller and the primary-side controller to provide the first feedback signal to the primary-side controller; The primary-side controller provides the first control signal to control the primary-side circuit according to the first feedback signal, and when the primary-side controller knows that an output current of the power converter is lower than a current threshold, the primary-side controller generates the first control signal according to the second feedback signal.

2. The power converter according to claim 1, wherein: When the output current is lower than the current threshold, the secondary-side controller enters a sleep state or a shutdown state to disable the first optocoupler.

3. The power converter according to claim 1, wherein: The primary side circuit includes an AC-to-DC circuit and a primary side coil, and the secondary side circuit includes a secondary side coil and a rectifier filter circuit.

4. The power converter according to claim 3, wherein: The primary side winding circuit comprises: an auxiliary winding coupled to the primary side coil; and a voltage divider circuit connected in parallel with the auxiliary winding and comprising a first resistor and a second resistor connected in series; A primary-side feedback terminal of the primary-side controller is coupled between the first resistor and the second resistor to receive the second feedback signal.

5. The power converter according to claim 3, wherein: Also includes: a current detection circuit, coupling the rectification and filtering circuit and the secondary side controller; The current detection circuit detects the output current and provides a current signal accordingly, and the secondary-side controller determines whether the output current is lower than the current threshold according to the current signal.

6. The power converter according to claim 3, wherein: Also includes a period detection circuit, coupling the secondary side coil and the secondary side controller; The period detection circuit detects a voltage conduction period of the secondary side coil and provides a period signal accordingly, and the secondary side controller determines whether the output current is lower than the current threshold according to the period signal.

7. The power converter according to claim 3, wherein: Also includes a frequency detection circuit, coupling the secondary side coil and the secondary side controller; The frequency detection circuit detects a voltage switching frequency of the secondary side coil and provides a frequency signal accordingly, and the secondary side controller determines whether the output current is lower than the current threshold according to the frequency signal.

8. The power converter according to claim 3, wherein: Also includes: a pulse detection circuit, coupling the secondary side coil and the secondary side controller; The AC to DC circuit further comprises: a power switch, coupling the primary side coil and the primary side controller; When the primary side controller learns through a voltage level of the first feedback signal or the second feedback signal that the output current is lower than the current threshold, the primary side controller controls the power switch to generate a specific pulse through the first control signal; the pulse detection circuit receives a secondary side voltage corresponding to the first control signal through the secondary side coil to provide a detection signal accordingly based on the specific pulse, and the secondary side controller enters a sleep state or a shutdown state based on the pulse signal.

9. The power converter according to claim 8, wherein: The primary-side controller adds a pulse signal to the first control signal to control the power switch to generate the specific pulse with a specific frequency or a specific period.

10. The power converter according to claim 3, wherein: Also includes: a second optical coupler coupling the primary-side controller and the secondary-side controller; When the primary-side controller learns through a voltage level of the first feedback signal or the second feedback signal that the output current is lower than the current threshold, the primary-side controller provides a second control signal to the second optocoupler; the second optocoupler couples the second control signal to the secondary-side controller, and the secondary-side controller enters a sleep state or a shutdown state according to the second control signal.

11. A feedback control method for a power converter, characterized in that: The power converter includes a primary side circuit, a primary side controller, a primary side winding circuit, a secondary side controller and a first optical coupler, and the feedback control method includes the following steps: The secondary-side controller generates a first feedback signal according to a DC output signal of the power converter, and provides the first feedback signal to the primary-side controller through the first optical coupler; The primary side winding circuit provides a second feedback signal corresponding to the DC output signal to the primary side controller; The primary-side controller generates a first control signal according to a first feedback signal, so as to control the primary-side circuit through the first control signal; and When the primary-side controller learns that an output current of the power converter is lower than a current threshold, the primary-side controller generates the first control signal according to the second feedback signal.

12. The feedback control method according to claim 11, characterized in that: It also includes the following steps: Detecting the output current and providing a current signal; The secondary-side controller determines, based on the current signal, that the output current is lower than the current threshold, and the power converter is in a light-load state; The secondary side controller informs the primary side controller of the light load state through the first feedback signal; The secondary-side controller enters a sleep state or a shutdown state to disable the first optocoupler; and The primary-side controller generates the first control signal according to the second feedback signal.

13. The feedback control method according to claim 11, characterized in that: The power converter further includes a secondary side coil, and the feedback control method further includes the following steps: Detecting a voltage conduction period of the secondary side coil and providing a period signal; The secondary-side controller determines, based on the periodic signal, that the output current is lower than the current threshold, and the power converter is in a light-load state; The secondary side controller informs the primary side controller of the light load state through the first feedback signal; The secondary-side controller enters a sleep state or a shutdown state to disable the first optocoupler; and The primary-side controller generates the first control signal according to the second feedback signal.

14. The feedback control method according to claim 11, characterized in that: The power converter further includes a secondary side coil, and the feedback control method further includes the following steps: Detecting a voltage switching frequency of the secondary side coil and providing a frequency signal; The secondary-side controller determines, based on the frequency signal, that the output current is lower than the current threshold, and the power converter is in a light-load state; The secondary side controller informs the primary side controller of the light load state through the first feedback signal; The secondary-side controller enters a sleep state or a shutdown state to disable the first optocoupler; and The primary-side controller generates the first control signal according to the second feedback signal.

15. The feedback control method according to claim 11, characterized in that: The power converter further includes a second optical coupler, and the feedback control method further includes the following steps: The primary-side controller determines that the output current is lower than the current threshold through a voltage level of the first feedback signal or the second feedback signal; The primary-side controller controls the power switch to generate a specific pulse through the first control signal; The primary-side controller generates the first control signal according to the second feedback signal; and The secondary-side controller enters a sleep state or a shut-down state according to a detection signal corresponding to the specific pulse to disable the first optical coupler.

16. The feedback control method according to claim 11, characterized in that: The primary side circuit further includes a power switch, and the feedback control method further includes the following steps: The primary-side controller determines that the output current is lower than the current threshold through a voltage level of the first feedback signal or the second feedback signal, and the power converter is in a light-load state; The primary side controller notifies the secondary side controller of the light load state through the second optical coupler; The primary-side controller generates the first control signal according to the second feedback signal; and The secondary-side controller enters a sleep state or a shutdown state to disable the first optocoupler.

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