Operation method of power conversion device, semiconductor chip, and the power conversion device

Abstract

To provide a power conversion device capable of reducing a switching loss.SOLUTION: A power conversion device comprises: a converter; a clamp capacitor; a main switch; a clamp switch; and a control circuit. The clamp capacitor is bonded to a primary winding of the converter, and the main switch is bonded to between the primary winding and a ground terminal in serial. The clamp switch is bonded to between the clamp capacitor and the main switch in serial, and the clamp switch, the main switch, and the primary winding are bonded to a common node. The control circuit periodically turns on the main switch, and turns on the clamp switch before the main switch is turned on. The control circuit determines a time when the clamp switch has to be turned on at the next time in accordance with a voltage of the common node detected before the main switch is turned on and a threshold value after the clamp switch is turned off and before the main switch is turned on.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. patent application Ser. No. 18 / 193,593, filed on Nov. 23, 2022, and entitled "Operation Method of Power Conversion Apparatus, Semiconductor Chip and Power Conversion Apparatus," and Chinese patent application Ser. No. 202211476002.9, filed on Nov. 23, 2022, and entitled "Self-Adjusting Soft Switching in Flyback Converter," the disclosures of which are incorporated herein by reference in their entireties.

[0002] The present invention relates to a power conversion device, a semiconductor chip, and an operating method of a power conversion device, and more particularly to a power conversion device capable of reducing switching loss. [Background technology]

[0003]

[0003] Flyback power converters are often used in various electronic products due to their simple structure and ability to provide electrical isolation through the transformer therein. However, conventional flyback power converters do not discharge the parasitic capacitors at the terminals of the switch when switching the primary coil, and instead turn on the switch in the form of hard switching, which results in serious switching losses. Therefore, how to design a more efficient power converter has become an urgent problem to be solved. Summary of the Invention

[0004]

[0004] An embodiment of the present disclosure relates to a power conversion device. The power conversion device includes a transformer, a clamp capacitor, a main switch, a clamp switch, and a control circuit. The transformer includes a first primary coil and a secondary coil, a first terminal of the first primary coil is used to receive an input voltage, and the secondary coil is used to generate an output voltage. The clamp capacitor has a first terminal coupled to the first terminal of the first primary coil. The main switch is connected in series between a second terminal of the first primary coil and a ground terminal. The clamp switch has a first terminal coupled to the second terminal of the clamp capacitor and a second terminal coupled to the first terminal of the main switch, the clamp switch is connected in series between the clamp capacitor and the main switch, and the second terminal of the clamp switch is further coupled to the second terminal of the first primary coil, such that the second terminal of the clamp switch, the first terminal of the main switch, and the second terminal of the first primary coil cross at a common node. The control circuit includes a voltage detection unit and a control signal generation unit. The voltage detection unit is used to compare the node voltage of the common node with a first threshold voltage. The control signal generation unit is used to periodically turn on the main switch, turn on the clamp switch to generate a reverse current at the second terminal of the primary coil before the main switch is turned on, turn off the clamp switch before the main switch is turned on, and discharge the equivalent capacitor on the common node by the reverse current after the clamp switch is turned on for a certain period of time, and determine a time for turning on the clamp switch before the main switch is turned on next time according to a magnitude relationship between the first threshold voltage detected by the voltage detection unit and the node voltage at a predetermined time before the main switch is turned on after the clamp switch is turned off, thereby controlling the voltage of the common node before the main switch is turned on next time to suppress switching loss of the main switch.

[0005] Another embodiment of the present disclosure relates to a chip that includes a control circuit for a power converter.

[0006] Another embodiment of the present disclosure relates to a method of operating a power converter, the power converter including a transformer, a main switch, a clamp capacitor, and a clamp switch, the transformer including a primary coil and a secondary coil, the main switch connected in series between a second terminal of the primary coil and a ground terminal, a first terminal of the clamp switch coupled to a second terminal of the clamp capacitor, the second terminal of the clamp switch coupled to a first terminal of the main switch and a second terminal of the primary coil, and the second terminal of the clamp switch, the first terminal of the main switch, and the second terminal of the primary coil cross at a common node. The method includes periodically turning on a main switch to charge the primary coil with an input voltage; turning on a clamp switch to generate a reverse current in a second terminal of the primary coil before the main switch is turned on; turning off the clamp switch before the main switch is turned on to discharge an equivalent capacitor on the common node by the reverse current after the clamp switch is turned on for a certain period of time; detecting a magnitude relationship between a node voltage of the common node and a first threshold voltage at a predetermined time point before the main switch is turned on after the clamp switch is turned off; and determining a time for which the clamp switch is turned on before the main switch is turned on next time according to the magnitude relationship between the node voltage and the first threshold voltage detected by a voltage detection unit at a predetermined time point before the main switch is turned on after the clamp switch is turned off, thereby controlling the voltage of the common node before the main switch is turned on next time to suppress switching loss of the main switch.

[0007]

[0007] According to the power conversion device disclosed herein, the time when the clamp switch will be turned on next can be determined each time depending on the amplitude of the node voltage of the common node before the main switch is turned on, so that the voltage of the common node can be reduced to a predetermined range in different circuits and environments, and the switching loss of the main switch can be effectively suppressed.

[0008]

[0008] Aspects of certain embodiments of the present disclosure can be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that the various features may not be drawn to scale. In fact, dimensions of the various features may be arbitrarily expanded or reduced for clarity of illustration. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a power converter according to one embodiment of the present disclosure. [Diagram 2] 2 is a flowchart of a method of operating the power converter of FIG. 1 according to one embodiment of the present disclosure. [Diagram 3] 3 is an operation timing diagram of the power conversion device of FIG. 1 according to the method of FIG. 2. [Figure 4] 4 is an operation timing diagram of the power conversion device of FIG. 1 according to another embodiment. [Diagram 5] 4 is an operation timing diagram of the power conversion device of FIG. 1 according to another embodiment. [Figure 6] FIG. 2 is a schematic diagram of a power converter according to another embodiment of the present disclosure. [Figure 7] FIG. 2 is a schematic diagram of a power converter according to another embodiment of the present disclosure. [Figure 8] FIG. 2 is a schematic diagram of a power converter according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010]

[0017] The same reference numbers are used throughout the drawings and detailed description to refer to the same or similar parts. Certain embodiments of the present disclosure will be readily understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0011]

[0018] The following disclosure provides many different embodiments or examples for implementing different features of the provided subject matter. Specific examples of components and configurations are described below. Of course, these are merely examples and are not intended to be limiting. In this disclosure, a reference to forming a first feature above or on a second feature may include an embodiment in which the first feature and the second feature are formed to be in direct contact, and may also include an embodiment in which an additional feature may be formed between the first feature and the second feature such that the first feature and the second feature are not in direct contact. Furthermore, the disclosure may repeat reference numbers and / or letters in various examples. This repetition is for simplicity and clarity, and does not dictate a relationship between the various embodiments and / or configurations described.

[0012]

[0019] The following detailed description of the embodiments of the present disclosure provides many applicable concepts that can be embodied in a wide variety of specific contexts. The described embodiments are merely exemplary and are not intended to limit the scope of the present disclosure.

[0013]

[0020] The present disclosure provides a power conversion device, a semiconductor chip, and an operating method of the power conversion device. The power conversion device of the present disclosure includes a transformer, a clamp capacitor, a main switch, a clamp switch, and a control circuit. A first terminal of the clamp capacitor is coupled to a first terminal of a primary coil of the transformer, and the main switch is connected in series between a second terminal of the primary coil and a ground terminal. The clamp switch is connected in series between a second terminal of the clamp capacitor and a first terminal of the main switch, and the second terminal of the clamp switch crosses the first terminal of the main switch and the second terminal of the primary coil at a common node. The control circuit periodically turns on the main switch, and after the main switch is turned on for a certain period of time, turns on the clamp switch to generate a reverse current. After the clamp switch is turned on, and before the main switch is turned on, the control circuit turns off the clamp switch to discharge an equivalent capacitor on the common node, and before the main switch is turned on, determines the time when the clamp switch is turned on next time according to the relationship between the voltage of the common node and a threshold voltage. According to the power conversion device disclosed herein, the time when the clamp switch will be turned on next can be determined each time depending on the amplitude of the node voltage of the common node before the main switch is turned on, so that the voltage of the common node can be reduced to a predetermined range in different circuits and environments, and switching losses of the main switch can be effectively suppressed.

[0014]

[0021] 1 is a schematic diagram of a power converter according to an embodiment of the present disclosure. As shown in FIG. 1, the power converter 100 may include a transformer 110, a clamp capacitor 120, a main switch 130, a clamp switch 140, and a control circuit 150. In this embodiment, the power converter may be, for example, an active clamp flyback power converter.

[0015]

[0022] The transformer 110 includes a primary coil 112 and a secondary coil 114. A first terminal of the primary coil 112 receives an input voltage V in, and the secondary coil 114 receives an output voltage V according to the change in current on the primary coil 112. out may be induced and output. The clamp capacitor 120 may have a first terminal and a second terminal, and the first terminal of the clamp capacitor 120 may be coupled to the first terminal of the primary coil 112. The main switch 130 may be connected in series between the second terminal of the primary coil 112 and a ground terminal GND. The clamp switch 140 may have a first terminal and a second terminal, and the first terminal of the clamp switch 140 may be coupled to the second terminal of the clamp capacitor 120, and the second terminal of the clamp switch 140 may be coupled to the first terminal of the main switch 130. That is, the clamp switch 140 may be connected in series between the clamp capacitor 120 and the main switch 130, and the second terminal of the clamp switch 140 may also be coupled to the second terminal of the primary coil 112 such that the second terminal of the clamp switch 140, the first terminal of the main switch 130, and the second terminal of the primary coil 112 intersect at a common node N1.

[0016]

[0023] The power converter 100 may operate in two main stages. In the first stage, the control circuit 150 may turn on the main switch 130, at which point the primary coil 112 is coupled to the input voltage V in Then, in a second stage, the control circuit 150 may turn off the main switch 130, at which point the energy stored in the primary coil 112 is transferred to the secondary coil 114 by electromagnetic induction, and the energy is transferred through the secondary coil 114 to the output terminal to generate an output voltage V out Furthermore, in the second stage, the power conversion device 100 may store leakage inductance energy of the primary coil 112 via the clamp capacitor 120, so that the power conversion efficiency of the power conversion device 100 can be increased. The power conversion device 100 repeatedly executes the operations of the first stage and the second stage to maintain the input voltage V in The output voltage V out It can be stably converted and output.

[0017]

[0024] However, when the main switch 130 is turned on, if the node voltage VSW of the common node N1 is relatively high, the main switch 130 is turned on when the drain-source voltage is relatively high, at which point the main switch 130 generates a relatively large switching loss, which corresponds to allowing the main switch 130 to be turned on in a hard switching state. To solve this problem, in this embodiment, the control circuit 150 may turn on the clamp switch 140 for a certain period of time, and then turn it off each time before the main switch 130 is turned on, to reduce the node voltage VSW of the common node N1, thereby reducing the drain-source voltage of the main switch 130 and reducing the switching loss of the main switch 130, which corresponds to allowing the main switch 130 to be turned on in a soft switching state. Furthermore, in this embodiment, in order to reduce the drain voltage of the main switch 130 to a predetermined range so that the main switch 130 can be turned on in a soft switching state as much as possible, the control circuit 150 detects whether the node voltage VSW of the common node N1 is sufficiently low each time before turning on the main switch 130, and according to an embodiment, may determine the time to turn on the clamp switch 140 next time.

[0018]

[0025] 1, the control circuit 150 may include a voltage detection unit 152 and a control signal generation unit 154. The voltage detection unit 152 may compare the node voltage VSW of the common node N1 with a threshold voltage VTH1. In this embodiment, VTH1 is set to 10 volts, but those skilled in the art may change the value as desired without being limited by this embodiment. The control signal generation unit 154 generates a main control signal SIG M1 and a clamp control signal SIG for controlling the clamp switch 140. C1The control signal generating unit 154 may periodically turn on the main switch 130 so that the power conversion device 100 can repeatedly alternate between the first stage and the second stage of operation.

[0019]

[0026] 2 is a flowchart of an operation method of M1 of the power converter 100 according to an embodiment of the present disclosure, and FIG. 3 is a timing diagram of the operation of the power converter 100 according to the method M1. As shown in FIG. 2, the method M1 may include repeating steps S110 to S150. In this embodiment, the main switch 130 may be, for example, an N-type transistor, and in FIG. 3, a main control signal SIG M1 is at a logic high potential, the main switch 130 is turned on, the power converter 100 operates in the first phase, and the main control signal SIG M1 is at a low logic level, the main switch 130 is turned off and the power converter 100 operates in the second phase. C1 is at a logic high potential, clamp switch 140 is turned on, and clamp control signal SIG C1 When is a logic low potential, clamp switch 140 is turned off.

[0020]

[0027] 3, clamp switch 140 is turned on during periods TB1, TB2, and TB3, clamp switch 140 is turned off after periods TB1, TB2, and TB3, and main switch 130 is turned on during periods TA1, TA2, and TA3. Furthermore, voltage detection unit 152 detects the magnitude relationship between node voltage VSW of common node N1 and threshold voltage VTH1 at predetermined points in time TC1, TC2, and TC3 before periods TA1, TA2, and TA3, and determines the time when clamp switch 140 will be turned on next.

[0021]

[0028] For ease of understanding, the following description may refer to Figures 1, 2, and 3 at the same time. In this embodiment, the control circuit 150 may turn on the clamp switch 140 (step S110) before the main switch 130 is turned on, and generate a reverse current in the second terminal of the primary coil 112 each time. After the clamp switch 140 is turned on for a certain period of time, the control circuit 150 turns off the clamp switch 140 (step S120) before the main switch 130 is turned on, and at this point, the reverse current flows through the equivalent capacitor C on the common node N1. pか It draws charge from the equivalent capacitor C p By discharging, the node voltage VSW of the common node N1 is pulled down. This allows the main switch 130 to be turned on with a small drain-source voltage (step S130), and the switching loss of the main switch 130 can be reduced.

[0022]

[0029] Equivalent capacitor C on the common node N1 p may comprise an overall equivalent capacitance of multiple capacitors, such as the parasitic capacitance of the main switch 130, the parasitic capacitance of the clamp switch 140, and the Miller capacitor at the corresponding position on the secondary side, so that the equivalent capacitance C p The magnitude of the equivalent capacitor C on its common node N1 may be related to the manufacturing process, the circuit in which it is located, and the operating environment (e.g., temperature). In this case, even if the power converter 100 is produced based on the same design, in actual operation, the equivalent capacitor C on its common node N1 may be related to the manufacturing process, the circuit in which it is located, and the operating environment (e.g., temperature). p That is, in order to reduce the node voltage VSW to an appropriate range, each power conversion device 100 may have a different equivalent capacitor C p The discharge of the two must be different.

[0023]

[0030] In order to enable the main switches in different power conversion devices 100 to be turned on in a soft switching state, in this embodiment, the control signal generating unit 154 may determine the magnitude relationship between the node voltage VSW detected by the voltage detecting unit 152 at a predetermined time point after the clamp switch 140 is turned off and before the main switch 130 is turned on (step S140) and determine the time at which the clamp switch 140 is turned on before the main switch 130 is turned on next time (step S150). In this way, by flowing an appropriate discharge current before the main switch 130 is turned on next time, the voltage of the common node N1 can be lowered and the switching loss of the main switch 130 can be more effectively suppressed.

[0024]

[0031] For example, as shown in FIG. 3, since the node voltage VSW detected by the voltage detection unit 152 at time TC1 is greater than the threshold voltage VTH1 before the period TA1 in which the main switch 130 is turned on, indicating that the drain-source voltage of the main switch 130 is still high when the main switch 130 is turned on in period TA1, the control signal generation unit 154 may extend the length of time that the clamp switch 140 is turned on before the main switch is turned on next time (i.e., before period TA2) to increase the backflow to the second terminal of the primary coil 112. That is, since the length of the period TB2 during which the clamp switch 140 is turned on for the second time is longer than the length of the period TB1 during which the clamp switch 140 is turned on for the first time, the clamp switch 140 is turned on for a longer period in the period TB2 and generates a larger reverse current. As a result, during the period after the clamp switch 140 is turned off and before the main switch 130 is turned on (i.e., the period between the periods TB2 and TA2), the power conversion device 100 is driven by the larger reverse current through the equivalent capacitor C pcan be discharged, thereby further pulling the node voltage VSW to a lower level before the main switch 130 is turned on. As shown in Fig. 3, the node voltage VSW detected by the voltage detection unit 152 at time point TC2 is smaller than the node voltage VSW detected by the voltage detection unit 152 at time point TC1, so that the switching loss is low when the main switch 130 is turned on again in period TA2.

[0025]

[0032] Furthermore, in this embodiment, when the voltage detection unit 152 detects that the node voltage VSW is less than the threshold voltage VTH1 at a predetermined time point TC2, the control signal generation unit 154 maintains and fixes the time for which the clamp switch 140 is turned on before the main switch 130 is turned on thereafter. For example, in Fig. 3, since the node voltage VSW detected by the voltage detection unit 152 at time point TC2 is less than the threshold voltage VTH1, the control signal generation unit 154 may turn on the clamp switch 140 for the same length of time next time, i.e., the length of the period TB3 may be equal to the length of the period TB2.

[0026]

[0033] However, the present application is not limited thereto. In some embodiments, the operating environment of the power converter 100, such as temperature, may change over time, and the input voltage V in may change over time in a test environment, in which case there is a possibility that the switching loss of the main switch 130 may not be effectively suppressed if the fixed clamp switch 140 is turned on for a long period of time. As a result, the control signal generator 154 may adjust the on-time of the clamp switch 140 by another mechanism, and does not necessarily have to fix the on-time of the subsequent clamp switch 140.

[0027]

[0034] 4 is an operation timing diagram of the power conversion device 100 according to another embodiment. In FIG. 4, when the voltage detection unit 152 detects that the node voltage VSW is greater than the threshold voltage VTH1 at time TC1, the control signal generation unit 154 may extend the clamp switch 140 so that the length of the period TB2 before the clamp switch 140 is turned on the next time is longer than the length of the period TB1. However, when the voltage detection unit 152 detects that the node voltage VSW is less than the threshold voltage VTH1 at time TC2, the control signal generation unit 154 may shorten the next on-time of the clamp switch 140 and make the length of the period TB3 shorter than the period TB2. In this way, the control signal generation unit 154 may also dynamically adjust the time that the clamp switch 140 is turned on as the operating conditions change.

[0028]

[0035] Fig. 5 is an operation timing diagram of the power conversion device 100 according to another embodiment. In the embodiment of Fig. 5, the voltage detection unit 152 can compare the node voltage VSW with two threshold voltages VTH1 and VTH2 at predetermined time points TC1, TC2, TC3 and TC4, and adjust the time at which the next clamp switch 140 is turned on according to the magnitude relationship between the node voltage VSW and the threshold voltages VTH1 and VTH2, and the threshold voltage VTH2 is less than the threshold voltage VTH1.

[0029]

[0036] For example, if the voltage detection unit 152 detects at time TC1 that the node voltage VSW is greater than the threshold voltage VTH1, the control signal generation unit 154 may extend the length of time for which the clamp switch 140 is next turned on, and make the length of period TB2 longer than the length of period TB1. If the voltage detection unit 152 detects at time TC2 that the node voltage VSW is less than the threshold voltage VTH1 and greater than the threshold voltage VTH2, the control signal generation unit 154 may maintain the length of time for which the clamp switch 140 is next turned on, such that the length of period TB3 is equal to the length of period TB2. However, if the voltage detection unit 152 detects at time TC3 that the node voltage VSW is less than the threshold voltage VTH2, the control signal generation unit 154 may shorten the length of time for which the clamp switch 140 is next turned on, and make the length of period TB4 shorter than the length of period TB3. In this embodiment, VTH1 is set to 10 volts and VTH2 is set to 5 volts, but those skilled in the art are not limited by this embodiment and may change these values ​​as desired.

[0030]

[0037] That is, only when the node voltage VSW is greater than the threshold voltage VTH1 or less than the threshold voltage VTH2, the control signal generating unit 154 adjusts the length of time that the clamp switch 140 is next turned on, and when the node voltage VSW is between the threshold voltages VTH1 and VTH2, the control signal generating unit 154 maintains the length of time that the clamp switch 140 is next turned on. In this way, it is possible to avoid adjusting the on-time of the clamp switch 140 too frequently, and a hysteresis-like control effect can be obtained. In other embodiments, the power conversion device 100 may be provided with three or more threshold voltages as desired.

[0031]

[0038] Further, in the embodiment of FIG. 1, the voltage detection unit 152 may include a comparator 1521. A first terminal of the comparator 1521 may be coupled to a first terminal of the main switch 130, and a second terminal of the comparator 1521 may receive the threshold voltage VTH1. That is, the voltage detection unit 152 may directly compare the node voltage VSW of the common node N1 with the threshold voltage VTH1 via the comparator 1521. However, the present disclosure is not limited thereto. In some embodiments, if the node voltage VSW is directly used as an input voltage to the comparator 1521, the comparator 1521 may be damaged because the node voltage VSW may have a higher voltage value. In this case, the voltage detection unit 152 may compare the magnitude relationship between the node voltage VSW and the threshold voltage VTH1 in another manner.

[0032]

[0039] 6 is a schematic diagram of a power converter according to another embodiment of the present disclosure. The power converter 200 may have a similar structure to the power converter 100 and operate according to a similar principle, but the voltage detection unit 252 in the power converter 200 may include resistors RA1 and RA2 and a comparator 2521. A first terminal of the resistor RA1 may be coupled to a first terminal of the main switch 130, a first terminal of the resistor RA2 may be coupled to a second terminal of the resistor RA1, and a second terminal of the resistor RA2 may be coupled to a ground terminal GND. Furthermore, a first terminal of the comparator 2521 may be coupled to a second terminal of the resistor RA1, and a second terminal of the comparator 2521 may receive a reference voltage VRA1 corresponding to a threshold voltage VTH1.

[0033]

[0040] That is, the voltage detection unit 252 may divide the node voltage VSW via the resistors RA1 and RA2 to reduce the voltage received at the first terminal of the comparator 2521. In this case, the reference voltage VRA1 may be less than the threshold voltage VTH1, and the ratio of the reference voltage VRA1 to the threshold voltage VTH1 may be equal to the ratio of the resistor RA2 to the sum of the resistors RA1 and RA2, that is, RA2 / (RA1+RA2). In this manner, the voltage detection unit 252 may be implemented using a conventional low-voltage comparator 2521.

[0034]

[0041] 7 is a schematic diagram of a power converter according to another embodiment of the present disclosure. The power converter 300 may have a similar structure to the power converter 100 and operate according to a similar principle, but the voltage detection unit 352 in the power converter 300 may include a diode D1, a resistor RB1, and a comparator 3521. The cathode of the diode D1 may be coupled to the first terminal of the main switch 130, the first terminal of the resistor RB1 may be coupled to the anode of the diode D1, and the second terminal of the resistor RB1 may receive a predetermined bias voltage VD1. The first terminal of the comparator 3521 may be coupled to the first terminal of the resistor RB1, and the second terminal of the comparator 3521 may receive a reference voltage VRB1 corresponding to the threshold voltage VTH1.

[0035]

[0042] In this embodiment, the predetermined bias voltage VD1 may be greater than the reference voltage VRB1. In this case, when the node voltage VSW is greater than the predetermined bias voltage VD1, the diode D1 is in a reverse bias state, so that the first terminal of the comparator 3521 receives the predetermined bias voltage VD1, and at that point, the comparator 3521 outputs a first voltage. Conversely, when the node voltage VSW is less than the predetermined bias voltage VD1 minus the threshold voltage of the diode D1, the diode D1 is in a forward bias state, so that the first terminal of the comparator 3521 receives the node voltage VSW + the threshold voltage of the diode D1, and at that point, the comparator 3521 outputs a second voltage different from the first voltage. That is, by appropriately setting the predetermined bias voltage VD1 and the reference voltage VRB1, the comparator 3521 can compare the node voltage VSW with the reference voltage VRB1 only when the node voltage VSW is small, and the comparator 3521 can be prevented from receiving an excessive voltage.

[0036]

[0043] 8 is a schematic diagram of a power converter according to another embodiment of the present disclosure. The power converter 400 may have a similar structure and operate according to a similar principle to the power converter 100, but the power converter 400 may include two primary coils 112, 412, and the voltage detection unit 452 may include resistors RC1, RC2 and a comparator 4521. In this embodiment, the power converter 400 may generate a detection voltage VS1 corresponding to the node voltage VSW through the primary coil 412, and may divide the detection voltage VS1 through the resistors RC1 and RC2.

[0037]

[0044] 8, a first terminal of the resistor RC1 may be coupled to a first terminal of the primary coil 412, a first terminal of the resistor RC2 may be coupled to a second terminal of the resistor RC1, and a second terminal of the resistor RC2 may be coupled to a second terminal of the primary coil 412 and a ground terminal GND. Further, a first terminal of the comparator 4521 may be coupled to the second terminal of the resistor RC1, and a second terminal of the comparator 4521 may receive a reference voltage VRC1 corresponding to the threshold voltage VTH1.

[0038]

[0045] In this embodiment, the power conversion device 400 generates a detection voltage VS1 corresponding to the node voltage VSW via the primary coil 412 and divides the voltage via resistors RC1 and RC2, so that the influence on the node voltage VSW in the detection process can be reduced and the input voltage of the comparator 4521 can be reduced.

[0039]

[0046] Furthermore, in the power conversion devices 100, 200, 300, and 400, the control signal generating unit 154 generates a periodic rectangular wave signal SIG M1 In addition to the clamp control signal SIG C1 , which controls the clamp switch 140 to control the main switch 130, and generates a clamp control signal SIG C1The time for which clamp switch 140 is turned on may be adjusted in each case by adjusting the pulse width of the reference voltage VR0. For example, in the embodiment of FIG. 1, control circuit 150 may include an analog circuit, and control signal generating unit 154 may include a comparator (not shown) that can compare reference voltage VR0 with sawtooth wave SIG (or triangular wave). In this case, control signal generating unit 154 adjusts the movement mode of sawtooth wave SIG (or triangular wave) or adjusts the level of reference voltage VR0 to adjust clamp control signal SIG C1 The pulse width may be controlled.

[0040]

[0047] However, the present disclosure is not limited thereto, and in some other embodiments, the control circuit 150 may include a digital circuit, and the control signal generating unit 154 may include a register and a counter. In this case, the control signal generating unit 154 stores a value related to the pulse width in a register, and the counter counts clock signals in the digital circuit, thereby generating the clamp control signal SIG according to the value stored in the register. C1 The pulse width may be controlled.

[0041]

[0048] Further, in some embodiments, the control circuit 150 may be provided on a separate chip CP1, for example, so that a circuit designer may more conveniently use the chip CP1 to detect the voltage of the primary coil therein and control its clamp switch and the main switch to be turned on in various power converter designs. Similarly, the control circuits 250, 350, 450 may be designed as chips for the circuit designer to use.

[0042]

[0049] In summary, the embodiments of the present disclosure provide a power converter, a semiconductor chip, and a method for operating the power converter. According to the power converter of the present disclosure, the time when the clamp switch is turned on next time can be determined according to the amplitude of the node voltage of the common node before the main switch is turned on each time, so that the voltage of the common node can be reduced to a predetermined range in different circuits and environments, and the switching loss of the main switch can be effectively suppressed.

[0043]

[0050] Spatially relative terms such as "lower", "below", "bottom", "upper", "top", "left", "right" and the like may be used herein for ease of description to describe the relationship between one component or feature and another component or feature as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein may be interpreted in a corresponding manner. When an element is referred to as being "connected" or "coupled" to another element, it will be understood that it may be directly connected or coupled to the other element or there may be intervening elements.

[0044]

[0051] As used herein, the terms "about," "substantially," "generally," and "approximately" are used to describe and account for slight variations. When used in relation to an event or circumstance, the term can refer to the exact occurrence of the event or circumstance, as well as instances where the event or circumstance approximately occurs. When used herein with respect to a given value or range, the term "about" generally means within ±10%, ±5%, ±1%, or ±0.5% of the given value or range. Ranges can be expressed herein from one endpoint to another endpoint, or between two endpoints. All ranges disclosed herein include endpoints unless otherwise stated. The term "substantially coplanar" can mean that two surfaces are positioned within a few micrometers (μm) of difference in position along the same plane, for example, within 10 μm, within 5 μm, within 1 μm, or within 0.5 μm of difference in position along the same plane. When numerical values ​​or characteristics are referred to as being "substantially" the same, the term can refer to values ​​within ±10%, ±5%, ±1%, or ±0.5% of the mean of the stated value.

[0045]

[0052] The above outlines features and detailed aspects of several embodiments of the present disclosure. The embodiments described in the present disclosure may be readily utilized as a basis for designing or modifying other processes and structures to carry out the same or similar purposes and / or achieve the same or similar advantages of the embodiments described herein. Such equivalent constructions do not depart from the spirit and scope of the present disclosure, and various changes, substitutions, and alterations may be made thereto without departing from the spirit and scope of the present disclosure. [Explanation of symbols]

[0046] 100, 200, 300, 400 Power Converter 110 Transformer 112, 412 Primary coil 114 Secondary coil 120 Clamp Capacitor 130 Main switch 140 Clamp Switch 150, 250, 350, 450 Control circuit 152, 252, 352, 452 Voltage detection section 154 Control signal generator 1521, 2521, 3521, 4521 comparators CP1 Chip C p Equivalent Capacitor D1 Diode GND Grounding terminal N1 common node RA1, RA2, RB1, RC1, RC2 resistors SIG Sawtooth SIG C1 Clamp Control Signal SIG M1 Main Control Signal TA1, TA2, TA3, TB1, TB2, TB3, TB4 period At TC1, TC2, and TC3 VD1 bias voltage VR0, VRA1, VRB1, VRC1 Reference voltage VS1 Detection voltage VSW Node Voltage VTH1, VTH2 threshold voltage V in Input voltage V out Output Voltage

Claims

1. A power conversion device, A transformer having a first primary coil and a secondary coil, wherein the first primary coil is configured to receive an input voltage and the secondary coil is configured to generate an output voltage, A clamp capacitor having a first terminal coupled to the first terminal of the first primary coil, A main switch connected to the second terminal of the first primary coil, A clamp switch is connected in series between the second terminal of the clamp capacitor and the main switch, wherein the main switch, the clamp switch, and the first primary coil intersect at a node. Control circuit and Equipped with, The aforementioned control circuit The main switch is periodically turned on in order to charge the first primary coil. Before the main switch is turned on, the clamp switch is turned on to generate a reverse current through the first primary coil. Before the main switch is turned on, the clamp switch is turned off to discharge the equivalent capacitor on the node connected to the main switch. The operation of the clamp switch is adjusted based on the monitored voltage at the node, thereby reducing the switching loss of the main switch. A power converter configured in such a way.

2. The power converter according to claim 1, wherein the control circuit is configured to compare the monitored voltage at the node with a first threshold voltage in order to adjust the length of time the clamp switch is turned on.

3. The power conversion device according to claim 2, wherein if the monitored voltage is greater than the first threshold voltage, the control circuit extends the duration for which the clamp switch is turned on before the main switch is turned on next time.

4. The power conversion device according to claim 2, wherein if the monitored voltage is less than the first threshold voltage, the control circuit then maintains the length of time the clamp switch is turned on before the main switch is turned on.

5. The power conversion device according to claim 2, wherein if the monitored voltage is less than the first threshold voltage, the control circuit reduces the length of time the clamp switch is turned on before the main switch is turned on next time.

6. The power conversion device according to claim 2, wherein if the monitored voltage is less than the first threshold voltage and greater than the second threshold voltage, the control circuit maintains the duration for which the clamp switch is turned on before the main switch is turned on, and the second threshold voltage is less than the first threshold voltage.

7. The power conversion device according to claim 6, wherein if the monitored voltage is less than the second threshold voltage at a predetermined time, the control circuit shortens the length of time the clamp switch is turned on before the main switch is turned on next time.

8. The power conversion device according to claim 1, further comprising a voltage detection unit connected to the node and configured to detect the monitored voltage at the node.

9. The power conversion device according to claim 8, wherein the voltage detection unit comprises a first resistor and a second resistor connected in series.

10. The power conversion device according to claim 8, wherein the voltage detection unit comprises a diode, a resistor, and a comparator.

11. The power conversion device according to claim 1, further comprising a second primary coil configured to generate a detection voltage corresponding to the voltage at the node.

12. The power conversion device according to claim 11, wherein the voltage detected by the second primary coil is divided by a resistor and input to the control circuit.

13. The power conversion device according to claim 1, wherein the equivalent capacitor on the node includes a parasitic capacitor associated with the main switch.

14. The power conversion device according to claim 1, wherein the transformer is a flyback transformer.

15. The power conversion device according to claim 1, wherein the main switch and the clamp switch are MOSFETs.

16. The power conversion device according to claim 15, wherein the control circuit is configured to generate gate control signals for turning the main switch and the clamp switch on and off.

17. The power converter according to claim 1, wherein the equivalent capacitor is related to the temperature of the power converter.

18. The power conversion device according to claim 1, further comprising a bias voltage circuit configured to supply a reference voltage to the control circuit for comparison with the monitored voltage at the node.

19. The power conversion device according to claim 1, wherein the control circuit comprises a digital circuit including a counter for adjusting the length of time the clamp switch operates based on a clock signal.

20. The power conversion device according to claim 1, wherein the control circuit is configured to turn off the clamp switch after a predetermined time delay before turning on the main switch.

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