Power Converters

Abstract

A power converter is provided. A capacitor is coupled to a primary winding (13) of a transformer forming part of an LC resonator. A capacitor (15) is coupled to a supply voltage input (Vcc) of a controller (10) to supply power to at least a portion of the controller (10).

Description

Technical Field

[0001] The present application relates generally to power converters. Background Art

[0002] A power converter is a device that converts electrical input power into electrical output power and includes a current converter and a voltage converter. A flyback converter is a voltage converter that provides galvanic isolation between an input terminal and any output terminal. A specific type of flyback converter is an asymmetric pulse width modulation (APWM) half-bridge (HB) flyback converter, referred to herein as an APWM HB flyback converter. An APWM HB flyback converter is essentially a converter in which the inductor of the converter is split to form a transformer so that the voltage ratio is multiplied based on the winding ratio of the transformer with the additional isolation advantage. In order to operate such an APWM HB flyback converter, a half-bridge including a high-side switch and a low-side switch is operated by a pulse width modulation signal to selectively provide energy to the transformer. The drive of the high-side switch and the low-side switch is controlled by a controller, which may include a processor programmed accordingly, specific hardware such as an application-specific integrated circuit (ASIC) or a field programmable gate array (FPGA) or other logic circuits, and a drive circuit for providing a drive signal to the switch.

[0003] Such a controller needs to be supplied with power to perform its functions. For example, the above-mentioned processor, ASIC, FPGA or other logic circuit and driver need to be supplied with supply voltage to be able to operate. In some previous implementations, the above-mentioned transformer is provided with an auxiliary winding, and the supply voltage of the supply controller is obtained from the voltage at such auxiliary winding.

[0004] However, such auxiliary windings require space and incur manufacturing costs. In other implementations operating at different output voltages, it may be necessary to use multiple auxiliary windings to provide the correct supply voltage to the controller for different output voltages or input voltages. Summary of the invention

[0005] According to one embodiment, a power converter is provided, comprising: at least one primary-side switch; a transformer, wherein the primary winding of the transformer is coupled to the at least one primary-side switch, and wherein the secondary winding of the transformer is coupled to the output terminal of the power converter; a capacitor coupled to the primary winding, wherein an LC resonator of the power converter comprises the capacitor and a leakage inductance of the transformer; and a controller configured to control switching of the at least one primary-side switch, wherein the controller comprises a supply voltage terminal configured to receive a supply voltage for supplying power to at least a portion of the controller, wherein the supply voltage terminal is coupled to the capacitor.

[0006] The above summary is intended only to give a brief overview of some aspects of some embodiments and should not be construed as limiting. In particular, other embodiments may include other features in addition to those explicitly given above. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a circuit diagram of a flyback converter according to one embodiment.

[0008] Figure 2 is a diagram of a controller according to one embodiment.

[0009] Figure 3 It is used to show Figure 1 Diagram of the operation of the flyback converter.

[0010] Figure 4 Measurement results of a flyback converter according to one embodiment are shown.

[0011] Figures 5 to 9 A flyback converter according to other embodiments is shown. DETAILED DESCRIPTION

[0012] Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings. These embodiments are given as examples only and should not be interpreted as limiting in any way. For example, although an embodiment may be described as including a plurality of features or elements, this should not be interpreted as limiting, and in other embodiments, some of the features or elements may be omitted and / or may be replaced by alternative features or elements. In addition to the features or elements explicitly shown and described, additional features or elements may also be used, such as features or elements conventionally provided in power converters such as asymmetric pulse width modulation half-bridge (APWM HB) flyback converter circuits, such as protection mechanisms (e.g., overcurrent protection) or feedback control.

[0013] Unless otherwise indicated, different embodiments can be combined with each other to form further embodiments. Variations and modifications described with reference to one of the embodiments can also be applied to the other embodiments.

[0014] In the illustrated and described embodiments, any direct electrical connection or coupling between elements, i.e., a connection or coupling without an intermediate element, may be replaced by an indirect connection or coupling, i.e., a connection or coupling including one or more additional intermediate elements, and vice versa, as long as the general purpose of the connection or coupling, such as providing a certain signal, certain information, or certain control, is essentially maintained. In other words, the connection or coupling may be modified, as long as the general purpose and function of the connection or coupling remain essentially unchanged. In the context of the present application, unless otherwise specifically noted, terms such as "connect", "couple", "connect to", or "coupled to" refer to electrical connections or couplings.

[0015] Embodiments relate to a power converter including a transformer and a capacitor coupled to a primary winding of the transformer. The leakage inductance of the primary winding and the capacitor may form an LC resonator of the power converter together with other components such as an additional inductor, which is also called an LC tank or a resonant tank. An example of such a power converter is a flyback converter. In the case of a flyback converter, the LC resonator defines the resonant frequency of the converter. Although a flyback converter is used as an example for such a power converter in the following, the techniques discussed herein may also be applied to other converters using such an LC resonator, wherein the LC resonator is driven by one or more primary side switches, for example according to an asymmetric pulse width modulation scheme.

[0016] In an embodiment, the voltage at the capacitor is used to supply power to at least a portion of the controller of the power converter. In particular, as will be described below, the voltage at the capacitor can have a sufficiently small change to make it suitable for the supply voltage. Additional details and implementations will be described below. To this end, the capacitor can be coupled to the supply voltage terminal of the controller so that the controller is supplied by the voltage at the capacitor. This coupling can be direct, i.e., with a simple low-ohmic connection, or indirect, i.e., with additional elements such as diodes or linear regulators between them, as long as the controller is supplied by the voltage obtained from the voltage at the capacitor.

[0017] Turning now to the accompanying drawings, Figure 1 is a circuit diagram showing an APWM HB flyback converter according to one embodiment. Figure 1 The APWM HB flyback converter includes a controller 10 that controls a high-side switch 11 and a low-side switch 12 via output terminals HSGD and LSGD, respectively. The high-side switch 11 and the low-side switch 12 are also referred to as primary-side switches. In other implementations, only a single primary-side switch may be provided. In the illustrated embodiment, the high-side switch 11 and the low-side switch 12 are NMOS transistors. However, in other embodiments, other types of switches such as other types of transistors may be used.

[0018] For the following description, a switch is referred to as being "on" or "closed" when it provides a low-ohmic connection between its terminals, and is referred to as being "off" or "open" when it provides essentially electrical isolation between the terminals (except for possible leakage current). Figure 1 In addition to the NMOS transistors shown, other types of field effect transistors such as PMOS transistors, bipolar junction transistors, or insulated gate bipolar transistors are examples of switches that may be used in embodiments.

[0019] As shown, the high-side switch 11 and the low-side switch 12 are coupled in series between a node and a reference voltage, such as ground, to which a direct current (DC) input voltage Vin is applied in operation. In some embodiments, a rectifier can be used to generate an input voltage Vin as in a conventional flyback converter based on an AC input voltage. This is just one example of an additional feature conventionally used in power converters such as voltage converters, which can also be implemented in the embodiments discussed herein.

[0020] The controller 10 is configured to control the high-side switch 11 and the low-side switch 12 via the output terminal HSGD and the output terminal LSGD according to any conventional technique used in power converters such as voltage converters. For example, the output current may be controlled in any conventional manner based on the output current or based on any other feedback information. Figure 1 The output voltage Vout of the flyback converter is used to modify the on-time of the high-side switch 11 or the low-side switch 12. In particular, when controlling the high-side switch 11 and the low-side switch 12, a technique such as zero voltage switching (ZVS) may be used.

[0021] A node between the switch 11 and the switch 12 is coupled to a first end of a primary winding 13 of a transformer 19. A second end of the primary winding 13 is coupled to ground via a capacitor 15 having a capacitance Cr.

[0022] The transformer 19 also includes a secondary winding 14. The points at the primary winding 13 and the secondary winding 14 indicate the winding direction. Figure 1 In the embodiment of the present invention, the primary winding 13 and the secondary winding 14 have opposite winding directions. The first end of the secondary winding 14 is coupled to the first output terminal to output the voltage Vout. The second end of the secondary winding 14 is coupled to the second output terminal (ground output terminal) via a diode 16. In addition, an output capacitor 17 with a capacitance Cout is coupled between the first output terminal and the second output terminal as shown, and the output capacitor 17 essentially acts as a filter.

[0023] The leakage inductance of the transformer 19, in particular the leakage inductance of the primary winding 13, and the capacitor 15 form an LC resonator that affects the performance of the flyback converter. In some embodiments, an additional optional inductor 18 may be provided as part of the LC resonator. The LC resonator is also called a resonant tank.

[0024] The capacitance Cr may be, for example, nanofarad (nF) or above, such as at least 1 nF, or at least 10 nF, or about 100 nF, but is not limited thereto. Additionally, in some implementations, the capacitance Cr may be less than 1 mF. Typically, when the converter is used in a resonant manner (using the following reference Figure 3 The resonance discussed above) determines the resonant frequency fres according to fres=1 / (2·π·SQRT(L·Cr)), where SQRT is the square path function and L is the leakage inductance of the transformer 19 (plus the inductance of the inductor 18, if this optional inductor is provided), so that for a predetermined resonant frequency fres, the value of Cr can be appropriately selected. Cr can also have a larger value when the converter is not used in a resonant mode.

[0025] As mentioned above, Figure 1 The flyback converter of corresponds to a conventional flyback controller and corresponds to known variants and modifications of conventional flyback converters, modifications and variations can be made. Unlike conventional flyback converters, in Figure 1 In an embodiment, the controller 10 is supplied with the voltage at the capacitor 15. In particular, the supply voltage input terminal Vcc of the controller 10 is coupled to the node between the capacitor 15 and the primary winding 13, and the ground terminal GND of the controller 10 is coupled to the ground. Since the capacitor 15 is also coupled to the ground, this means that the voltage between the terminal Vcc and the terminal GND of the controller 10 corresponds to the voltage Vcr across the capacitor 15. This voltage is used as a supply voltage for the controller 10, supplying power to one or more components of the controller 10. As used herein, the supply voltage should be understood in the general sense of the word as a voltage that supplies power required for operation to a circuit, and the supply voltage should be distinguished from an input signal (which may also be a voltage signal) that carries information processed within the controller 10. This does not exclude that the supply voltage to the controller 10 may also carry some information used, but this is an optional function in addition to the function of being a supply voltage.

[0026] By using the voltage at or across the capacitor 15 as the supply voltage, for example, no auxiliary winding may be required to generate the supply voltage, and no external supply voltage may be required. In other embodiments, as will be discussed later, the number of auxiliary windings may be reduced.

[0027] Figure 2A schematic diagram of a controller 20 according to one embodiment is shown. Figure 1 An example of a controller 10 is shown. Figure 2 The controller 20 includes control logic 21. The control logic 21 may include one or more logic circuits, one or more application specific integrated circuits (ASICs) or portions thereof, a field programmable gate array, one or more processors, and / or other control circuits. Figure 2 The control logic 21 in the embodiment of receives one or more feedback signals via the terminal FB. The feedback signal may be, for example, a signal indicating the output voltage of the flyback converter or the output load of the flyback converter. Any feedback signal also used in a conventional flyback converter may be used, based on which the flyback converter is controlled.

[0028] In response to the feedback signal, the control logic 21 controls the high-side driver 22 to output a control signal for a high-side switch such as the high-side switch 11 via the output terminal HSGD, and controls the low-side driver 23 to output a control signal to a low-side switch such as the high-side switch 11 via the terminal LSGD. Figure 1 In particular, to operate the APWM HB flyback converter, the high-side switch and the low-side switch are turned on and off in an alternating manner using a dead time (time when both switches are off) between turning on and off.

[0029] exist Figure 2 In an embodiment, the control logic is supplied by a supply voltage from a terminal Vcc and a terminal GND. Figure 1 In the case of implementation methods such as Figure 1 As shown, terminal Vcc is coupled to capacitor 15, and terminal GND is coupled to ground. In this way, the control logic 21 is supplied with power to perform the control briefly described above, and in particular controls the high-side driver 22 and the low-side driver 23. In other embodiments, additionally or alternatively, the high-side driver 22 and / or the low-side driver 23 may be supplied by a supply voltage received at terminal Vcc. In other embodiments, the high-side driver 22 may be supplied by an additional circuit such as a bootstrap circuit to generate an appropriate voltage. In other embodiments, additional supply voltage terminals may be provided to supply the high-side driver 22 and / or the low-side driver 23. However, in the embodiments described herein, at least a portion of the controller 20 is supplied by a capacitor such as a LC resonator coupled to the flyback converter. Figure 1 The node of capacitor 15 is supplied with the supply voltage obtained.

[0030] In referring to Figures 5 to 9 Before describing another embodiment of the flyback converter, reference will be made to Figure 3 and Figure 4 Brief Description Figure 1 Example operations of implementations of the invention.

[0031] Figure 3 Shows Figure 1 30 shows an example switching of the high-side switch 11, and curve 31 shows an example switching of the low-side switch 12, where high levels of curves 30 and 31 indicate that the corresponding switches are closed, and low levels of curves 30 and 31 indicate that the corresponding switches are open. It can be seen that the high-side switch 11 and the low-side switch 12 are periodically opened and closed in an alternating manner. The switching cycle length is Figure 3 The on-time of the high-side switch 11 is represented as T, and the on-time of the high-side switch 11 is represented as Ths.

[0032] Curve 32 shows the secondary current Isec flowing from the secondary winding 14 to the terminal output voltage Vout on the secondary side, and curve 33 shows the current Ihb flowing from the node between the high-side switch 11 and the low-side switch 12 to the first end of the primary winding 13. Curve 34 shows the magnetizing current in the transformer 19, and curve 35 shows the voltage Vcr across the capacitor 15 (corresponding to Figure 1 ), and curve 36 shows the voltage Vhb at the node between the high-side switch 11 and the low-side switch 12. Some of the above voltages and currents are also shown in Figure 1 is shown in .

[0033] When operating the flyback converter at or near the resonant frequency of the above LC resonator, the Figure 3 In the box 37 of , in particular, are the resonances visible in the curve 32 (Isec) and the curve 33 (Ihb).

[0034] Before discussing the supply voltage Vcr to the controller 10 in more detail, for the sake of completeness, Figure 1 General operation of a flyback converter.

[0035] In operation phase I, the high-side switch 11 is turned on and the low-side switch 12 is turned off. Therefore, the input voltage Vin is applied to the first end of the primary winding 13 of the transformer 19 and the capacitor 15. As can be seen in the curve 33, the current Ihb increases and the capacitor 15 is charged, causing Vcr to increase during this period. The current Isec during this period can be ignored because the diode 16 is reverse biased during this stage.

[0036] In the operation phase II, both switches 11, 12 are turned off, which is also called dead time. The inductance of the transformer 19 forces the current established during the operation phase I to keep flowing, and at the beginning of the phase II, the magnetizing current Im decreases slowly while the current Ihb decreases more sharply. Since both switches 11, 12 are turned off, the voltage Vhb decreases (the charging / discharging parasitic capacitance of the switches 11, 12, also called the output capacitance) until the voltage Vhb is clamped by the parasitic diode of the low-side switch 12.

[0037] In operation phase III, the high side switch 11 is turned off and the low side switch 12 is turned on. Vcr continues to decrease. Isec and Ihb show a sinusoidal shape caused by the resonance. In particular, compared to operation phase I, the voltage in the transformer secondary winding 14 is inverted by the forward biased diode 16. The secondary current Isec starts to increase, and this secondary current is reflected to the primary side and added to the magnetizing current.

[0038] It can be seen that when the low-side switch 12 is turned on, so-called zero voltage switching is achieved because the voltage Vhb is zero when the low-side switch is turned on.

[0039] In operation phase IV, both switches 11, 12 are turned off, which is also called dead time. Somewhat similar to operation phase II, the current established in transformer T1 forces Vhb to increase until the body diode of the high-side switch clamps the voltage. This enables zero voltage switching of the high-side switch 11 when entering operation phase I again, where the high-side switch 11 is turned on, in an embodiment.

[0040] As mentioned above, curve 35 represents the voltage across capacitor 15, which essentially serves as the supply voltage at terminal Vcc of controller 10. It can be seen that although this voltage varies, Figure 3 In the example of FIG. 1 , this voltage is always higher than approximately 45 V and lower than approximately 65 V, so that by designing the circuit of the controller 10 accordingly, this voltage can be used as the supply voltage.

[0041] In this regard, it should be noted that according to <vcr>=N*Vout, the average voltage Vcr depends on the output voltage Vout, where N is the transformer winding ratio Np / Ns of the transformer 19, where Np is the number of windings of the primary winding 13, and Ns is the number of windings of the secondary winding 14, and <vcr>is the average value of the voltage Vcr. This means that when, for example, Figure 1 and Figure 2 The feedback mechanism briefly mentioned keeps the output voltage constant while also keeping the average value of the voltage Vcr constant, which improves the availability as a supply voltage.

[0042] To further illustrate, Figure 4 Shows Figure 1 The measured results of a practical implementation of the converter. Figure 4 The upper part of FIG. 4 shows curves 40 to 44, and Figure 4 An enlarged form of the curves 40 to 44 within the box 45 in the upper part is shown in the lower part of . Curve 40 shows the voltage Vcr across the capacitor 15, and curve 43 shows the current Icr charging / discharging the capacitor 15. Curve 41 shows the control signal (output LSGD) for the low-side switch 12, and curve 44 shows the voltage Vhb. In this particular implementation, the voltage Vcr has an average (median) value of 15.7278V, which has relatively small variations. It should be noted that, as mentioned above, the value of Vcr depends on both the output voltage Vout for which the converter is designed and the winding ratio N (according to the above equation), so that different voltages may appear as in Figure 3 A voltage between 40V and 70V or Figure 4 The voltage is about 16V.

[0043] Now refer to Figures 5 to 9 Additional implementations are described. Figures 5 to 9 The implementation method is Figure 1 In order to avoid repetition, corresponding elements have the same reference numerals and will not be described in detail again. It should be noted that this does not imply that the elements must be identical. For example, as will be explained below, the capacitor 15 can be connected to the primary winding 13 of the transformer 19 and the switches 11, 12 in different ways, but since the capacitor is always used as a capacitor for the LC resonator, the capacitor is always given the reference numeral 15. However, such modifications and the same Figure 1 All other additions and variations compared to the embodiments will be described in detail below.

[0044] exist Figure 5 In an embodiment of the invention, the transformer 19 comprises an auxiliary winding 50 having the same winding direction as the secondary winding 14 and a different direction than the primary winding 13. The auxiliary winding 50 can also be used to generate a supply voltage for the controller 10. Figure 5 Embodiments of can be used, for example, in converters in which different output voltages Vout can be generated by a voltage converter. As explained above, the voltage across the capacitor 15 is directly related to the output voltage Vout via the turns ratio of the transformer 19. For varying output voltages, this may mean that not for all output voltages the voltage across the capacitor 15 is suitable as a supply voltage for the controller 10. Therefore, the voltage at the capacitor 15 is provided to the supply selector circuit 52, and additionally, the voltage at the secondary winding 50 is provided to the supply selector circuit 52 via the diode 51. The supply selector circuit 52 is essentially a multiplexer and selects the voltage at the capacitor 15 as the supply voltage (so that the controller 10 is configured as for Figure 1 The auxiliary winding 50 may be selected as the supply voltage to be supplied to the terminal Vcc, for example, the voltage at the capacitor 15 may be selected for a first range of output voltages Vout, and the voltage at the auxiliary winding 50 may be selected for a second range of output voltages Vout different from the first range. The size of the auxiliary winding 50 (the number of windings) may be determined so that a suitable supply voltage is provided to the controller 10 in both cases. In some conventional cases, two auxiliary windings may be required in such a case, so in some embodiments, the number of auxiliary windings required may be reduced by using the voltage at the capacitor 15 as the selectable supply voltage.

[0045] Figure 6 An embodiment is shown with an additional current sensing shunt resistor 60 having a resistance Rs coupled between the low side switch 12 and ground. The node between the shunt resistor 60 and the low side switch 12 is coupled to the current sensing terminal Cs of the controller 10. Thus, the voltage at the terminal Cs indicates the current flowing through the low side switch 12. This can be used as a feedback signal, for example, for controlling the switching of the switches 11, 12, or can also be used for other purposes such as overcurrent protection. In addition, Figure 6 The implementation method corresponds to Figure 5 It should be noted that such a shunt resistor can also be arranged in Figure 1 In the embodiment, this is for an embodiment ( Figure 5 The variations of the embodiments) are also applicable to other embodiments ( Figure 1 Examples of embodiments of the present invention), as initially mentioned, are also within the scope of the present application.

[0046] It should be noted that the shunt resistor 60 may also be connected in other ways. Figure 7 An example is shown in FIG. 1 , in which a shunt resistor 60 is coupled between the capacitor 15 and ground. In addition, Figure 7 The implementation method corresponds to Figure 6 implementation method.

[0047] exist Figure 1 , Figure 5 , Figure 6 and Figure 7 In the embodiment of the present invention, the primary winding 13 and the capacitor 15 are coupled in series between the node between the switch 11 and the switch 12 and the ground. In other embodiments, the primary winding 13 and the capacitor 15 can be coupled between the input voltage Vin and the node between the high-side switch 11 and the low-side switch 12. Figure 8 An example for such an implementation is shown in .

[0048] In such a configuration, the roles of the high-side switch 11 and the low-side switch 12 with respect to the operation of the converter may be reversed. Figure 8 In an embodiment, the controller 10 is again supplied by the voltage across the capacitor 15. A first terminal of the capacitor 15, which also receives the input voltage Vin, is coupled to a terminal Vcc of the controller 10, and a second terminal of the capacitor 15, which is also coupled to the primary winding 13, is coupled to a terminal IC GND of the controller 10, which serves as an internal ground or reference potential for the voltage supply of the controller 10. This ground is different from the ground of the entire circuit (e.g. the ground to which the low-side switch 12 is connected, which is therefore referred to as IC GND).

[0049] In order to provide isolation between this internal ground and the external ground of the controller 10, an isolation barrier 80 is provided between the terminal HSGD, the terminal LSGD and the switch 11, the switch 12. Such an isolation barrier 80 can provide DC isolation using, for example, an optocoupler or a pulse transformer. In particular, as can also be seen, the IC GND is isolated from the source terminals of the switch 11, the switch 12. One reason for doing this is that in some implementations, the switch 11, the switch 12 requires a gate-source voltage of 0 to open and a gate-source voltage of between 5V and 15V to fully close, and in order to ensure correct switch control, an isolation barrier 80 is provided.

[0050] It should be noted that also in Figure 8 In an embodiment, an auxiliary winding such as the auxiliary winding 50 and a supply selector such as the supply selector circuit 52 may be provided together.

[0051] In reference Figure 1 and Figures 5 to 8 In the embodiment under discussion, a supply voltage is generated at the terminal Vcc of the controller 10, such as Figure 2 As shown, this supply voltage can be used in particular to supply power to the control logic of the controller 10. As already mentioned with reference to Figure 2 As mentioned, in other embodiments, the voltage at the capacitor 15 may also be used to provide a driver such as Figure 2 The high-side driver 22 supplies power. Fig. 9 The corresponding implementation is shown in FIG.

[0052] exist Fig. 9 In the embodiment, the capacitor 15 is coupled between the node between the switches 11 and 12 on the one hand and the primary winding 13 on the other hand. In addition, the node between the switches 11 and 12 is coupled to the terminal HSGD GND of the controller 10, and the node between the capacitor 15 and the primary winding 13 is coupled to the terminal HSGD Vcc of the controller 10. The voltage between the terminal HSGD Vcc and the terminal HSGD GND is used in the controller 10 to supply a high-side driver such as Figure 2 The high-side driver 22 of FIG. 1 is shown in FIG. 1 . In such a case, no additional circuitry such as a bootstrap circuit is required to supply the high-side driver. Other components of the controller 10 such as the control logic may then be supplied in any conventional manner, or the supply voltage for such components may be derived from the voltage at terminal HSGD Vcc internal to the controller 10.

[0053] Therefore, as can be seen from the above-described embodiments, there are various possibilities for using the voltage at the capacitor of the LC resonator coupled to the primary winding of the transformer of the voltage converter to provide a supply voltage to the controller of the voltage converter.

[0054] It should be noted that the APWM HB flyback converter is merely a non-limiting example for illustration purposes and that the techniques described herein may generally be applied to converters in which a capacitor is coupled to the primary winding of a transformer of the converter.

[0055] Some implementations are defined by the following examples.

[0056] Example 1. A power converter, comprising: at least one primary-side switch (11, 12); a transformer, wherein a primary winding (13) of the transformer (19) is coupled to the at least one primary-side switch (11, 12), and wherein a secondary winding (14) of the transformer (19) is coupled to an output terminal of the power converter; a capacitor (15) coupled to the primary winding (13), wherein an LC resonator of the power converter comprises the capacitor (15) and a leakage inductance of the transformer (19); and a controller (10), wherein the controller (10) is configured to control switching of the at least one primary-side switch (11, 12), wherein the controller (10) comprises a supply voltage terminal (Vcc), wherein the supply voltage terminal (Vcc) is configured to receive a supply voltage for supplying power to at least a portion of the controller (10), wherein the supply voltage terminal (Vcc) is coupled to the capacitor (15).

[0057] Example 2. A power converter according to Example 1, wherein a supply voltage terminal (Vcc) of the controller (10) is coupled to a first terminal of the capacitor (15), wherein a reference voltage terminal (GND) of the controller (10) is coupled to a reference potential, and wherein a second terminal of the capacitor (15) is coupled to the reference potential.

[0058] Example 3. The power converter according to Example 1, wherein a first terminal of the capacitor (15) is coupled to the supply voltage terminal, and a second terminal of the capacitor (15) is coupled to a reference voltage terminal (IC GND) of the controller (10).

[0059] Example 4. A power converter according to Example 1, wherein the at least one primary side switch (11, 12) includes a high side switch (11) coupled between an input voltage (Vin) node and an intermediate node and a low side switch (12) coupled between the intermediate node and a reference potential, wherein a first end of the primary winding (13) is coupled to the intermediate node.

[0060] Example 5. A power converter according to Example 4, wherein the capacitor (15) is coupled between the second end of the primary winding (13) and the reference potential, and wherein a further node between the primary winding (13) and the capacitor (15) is coupled to the supply voltage terminal (Vcc).

[0061] Example 6. The power converter of Example 4 or 5, further comprising a shunt resistor (60) coupled between the low-side switch (12) and the reference potential.

[0062] Example 7. The power converter of Example 6, wherein the capacitor (15) is coupled to a node between the low-side switch (12) and the shunt resistor (60).

[0063] Example 8. A power converter according to Example 4, wherein the second end of the primary winding (13) is coupled to the first terminal of the capacitor (15), wherein the second terminal of the capacitor (15) is coupled to the input voltage (Vin) node and the supply voltage terminal (Vcc), and wherein the first terminal of the capacitor (15) is coupled to a reference voltage terminal (IC GND) of the controller (10).

[0064] Example 9. The power converter of Example 8, further comprising an isolation barrier (80) between the controller and the at least one primary-side switch (11, 12).

[0065] Example 10. A power converter according to Example 4, wherein the capacitor (15) is coupled between the intermediate node and the first end of the primary winding (13), wherein the second end of the primary winding (13) is coupled to the input voltage (Vin) node, wherein a further node between the capacitor (15) and the primary winding (13) is coupled to the supply voltage terminal (Vcc), wherein the intermediate node is coupled to a reference voltage terminal (HSGDGND) of the controller (10), and wherein at least a portion of the controller (10) includes a high-side driver (22) of the controller.

[0066] Example 11. A power converter according to any of Examples 4 to 10, wherein the reference potential is ground.

[0067] Example 12. A power converter according to any one of Examples 1 to 11, wherein the transformer (19) further includes an auxiliary winding (50), and wherein the power converter further includes a supply selector circuit (52), the supply selector circuit (52) being configured to selectively couple the capacitor (15) or the auxiliary winding (50) to the supply voltage terminal (Vcc).

[0068] Example 13. A power converter according to Example 12, wherein the supply selector circuit (52) is configured to selectively couple the capacitor (15) or the auxiliary winding (50) to the supply voltage terminal (Vcc) based on an output voltage (Vout) of the power converter.

[0069] Example 14. A power converter according to any one of Examples 1 to 13, wherein the power converter is a flyback converter.

[0070] Although specific embodiments have been shown and described herein, it will be appreciated by those of ordinary skill in the art that various alternative and / or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. The present application is intended to cover any modifications or variations of the specific embodiments discussed herein. Therefore, the present invention is intended to be limited only by the claims and their equivalents.< / vcr> < / vcr>

Claims

1. A power converter, comprising: a first primary side switch; a transformer, the transformer comprising a primary winding, a secondary winding inductively coupled to the primary winding, and an auxiliary winding inductively coupled to the primary winding, the primary winding of the transformer being coupled to the first primary-side switch, and the secondary winding of the transformer being coupled to an output terminal of the power converter; a capacitor arranged in series with the primary winding, the LC resonator of the power converter comprising the capacitor and the inductance of the primary winding of the transformer; a controller operative to control switching of the first primary side switch between on and off to control current flow through the primary winding, the controller comprising a supply voltage input terminal operative to receive a supply voltage from the capacitor connected to the primary winding, the supply voltage from the capacitor operative to supply power to the controller; as well as a supply selector circuit operated to selectively switch between coupling a supply voltage supplied from the capacitor and coupling an auxiliary voltage generated by the auxiliary winding to supply power to the supply voltage input terminal, wherein a first terminal of the capacitor is coupled to the supply voltage input terminal, and The second terminal of the capacitor is coupled to a reference voltage terminal of the controller.

2. The power converter according to claim 1, wherein: A reference voltage terminal of the controller is coupled to a reference voltage potential; wherein a first terminal of the capacitor is operated to supply the supply voltage to the supply voltage input terminal; and wherein a second terminal of the capacitor is coupled to the reference voltage potential.

3. The power converter according to claim 1, wherein: The first primary side switch is a high side switch coupled between an input voltage source and an intermediate node; wherein the low-side switch is coupled between the intermediate node and a reference voltage potential; and Wherein, the first end of the primary winding is coupled to the intermediate node.

4. The power converter according to claim 3, wherein: The capacitor is coupled between the second end of the primary winding and the reference voltage potential. 5 . The power converter of claim 3 , further comprising a shunt resistor coupled between the low-side switch and the reference voltage potential.

6. The power converter according to claim 5, wherein: The capacitor is coupled between the low-side switch and the shunt resistor. 7 . The power converter of claim 1 , further comprising an isolation barrier disposed between the controller and the first primary-side switch.

8. The power converter according to claim 1, wherein: The supply selector circuit is operated to switch between connecting the capacitor to the supply voltage input terminal and connecting the auxiliary winding to the supply voltage input terminal based on an output voltage output from an output terminal of the power converter.

9. The power converter according to claim 1, wherein: The power converter is a flyback converter.

10. The power converter of claim 1, further comprising: An inductor component is arranged in series with the primary winding and the first primary side switch, the combination of the inductance of the inductor component and the inductance of the primary winding being part of an LC resonator of the power converter, the combination defining a resonant frequency of the power converter.

11. The power converter of claim 1 , further comprising: A controller is operable to adjust a timing of activating the first primary side switch according to a magnitude of an output voltage generated from the secondary winding.

12. The power converter of claim 1 , further comprising: A second primary-side switch is connected in series with the first primary-side switch.

13. The power converter according to claim 12, wherein: A series combination of the primary winding and the capacitor is arranged in parallel with the second primary side switch.

14. The power converter of claim 13, further comprising: A controller is operable to adjust a timing of activating the first primary side switch and the second primary side switch according to a magnitude of an output voltage generated from the secondary winding.

15. The power converter according to claim 3, wherein: The combination of the capacitor and the primary winding is arranged in parallel with the first primary side switch.

16. The power converter according to claim 1, wherein: The flow of current through the primary winding controlled by the first primary side switch is operated to generate an output voltage from the secondary winding and to generate the supply voltage, which is stored in the capacitor.

17. The power converter according to claim 1, wherein: The amplitude of the supply voltage varies within a constant range.

18. An apparatus for controlling a power converter, the power converter comprising a transformer, the transformer comprising a primary winding, a secondary winding inductively coupled to the primary winding, and an auxiliary winding inductively coupled to the primary winding, the apparatus comprising: A controller, the controller being operable to: Controlling the switching of a first switch of the power converter between on and off to control the current flow through the primary winding, wherein the primary winding of the transformer is coupled to the first switch and the secondary winding of the transformer is coupled to the output terminal of the power converter; controlling, via the controlled switching, a resonant operation of an LC resonator of the power converter, the LC resonator comprising a capacitor of the power converter and the primary winding arranged in series, the resonance of the LC resonator generating a supply voltage stored in the capacitor; receiving, via a supply voltage input terminal of the controller, a supply voltage stored in the capacitor; wherein the first terminal of the capacitor is coupled to the supply voltage input terminal, wherein the second terminal of the capacitor is coupled to a reference voltage terminal of the controller, and Wherein, the supply selector circuit of the power converter is operated to selectively switch between coupling the supply voltage supplied from the capacitor and coupling the auxiliary voltage generated by the auxiliary winding to supply power to the supply voltage input terminal.

19. The device according to claim 18, wherein: The supply selector circuit is operated to switch between connecting the capacitor to the supply voltage input terminal and connecting the auxiliary winding to the supply voltage input terminal based on an output voltage output from an output terminal of the power converter.

20. A method for controlling a power converter, the power converter comprising a transformer, the transformer comprising a primary winding, a secondary winding inductively coupled to the primary winding, and an auxiliary winding inductively coupled to the primary winding, the method comprising: Switching, via a controller, a first switch of the power converter between on and off to control current flow through the primary winding, wherein the primary winding of the transformer is coupled to the first switch and the secondary winding of the transformer is coupled to an output terminal of the power converter; controlling, via the switching, a resonant operation of an LC resonator of the power converter, the LC resonator comprising a capacitor and the primary winding arranged in series, the resonance of the LC resonator generating a supply voltage at a first node of the capacitor; and receiving, via a supply voltage input terminal of the controller, a supply voltage generated by a first node of the capacitor, wherein a first node of the capacitor is coupled to the supply voltage input terminal, wherein the second node of the capacitor is coupled to a reference voltage terminal of the controller, and The method further includes operating a supply selector circuit of the power converter to selectively switch between coupling a supply voltage supplied from the capacitor and coupling an auxiliary voltage generated by the auxiliary winding to supply power to the supply voltage input terminal.

21. The method of claim 20, further comprising operating the supply selector circuit to switch between connecting the capacitor to the supply voltage input terminal and connecting the auxiliary winding to the supply voltage input terminal based on an output voltage output from an output terminal of the power converter.

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