Power converter including buck-boost converter

Abstract

A power converter including a buck-boost converter is disclosed. The buck-boost converter comprises a transistor (11) having a terminal, e.g., a source terminal, coupled to the output terminal (17B) and to the terminal of the capacitor (15).

Description

Technical Field

[0001] The present application relates to a power converter including a buck-boost converter. Background Art

[0002] A power converter is a device that generally converts input electrical power (voltage, current) into output electrical power (voltage, current). For example, the input voltage, which may be supplied by the mains voltage of a power grid, a battery in a vehicle, etc., is converted into an output power with a voltage and current suitable for a specific electrical appliance.

[0003] The power converter comprises a switched mode power supply (SMPS) in which the operation of a switch turned on and off according to some switching scheme, such as a pulse width modulation scheme, determines the output voltage and / or current. Such a switch may be controlled by a controller, for example based on some feedback indicating the actual output voltage and / or current.

[0004] Some power converters provide galvanic isolation, where, for example, a transformer is used to couple a primary side that receives input electrical power to a secondary side that outputs output electrical power. One type of such power converter that provides galvanic isolation is a flyback converter, where operation of a switch on the primary side controls power transfer to the secondary side.

[0005] A controller that controls the above-mentioned switches and / or other parts of the power converter must be powered. In power converters that provide galvanic isolation, auxiliary windings of transformers are sometimes used to provide power. For example, in a power converter with a variable output voltage, the auxiliary voltage provided by such an auxiliary winding will also vary, and it is desirable to adjust the voltage provided by the auxiliary winding to a predefined value that can be used by the controller. For example, for a power converter for USB-PD (Universal Serial Bus - Standardized Power Transmission for USB Bus), the output voltage can range from 5V to 48V. In the case where the minimum requirement for powering the controller is, for example, 12V, the power supply voltage will vary by the same multiple as the output voltage, for example, from 12V to 115V, by tapping the auxiliary winding. It is very difficult, or even impossible, to design a controller that can operate within the range of its power supply voltage.

[0006] To solve this problem, various conventional solutions have been proposed, such as using a depletion-mode MOSFET together with a Zener diode to clamp the maximum voltage, using a voltage-divided auxiliary winding, using a combination of a clamping circuit and a boost converter, or a Greinacher half-wave voltage doubler. While these solutions are generally feasible at least within some voltage ranges, they may have high area requirements for implementing the circuit, and therefore a high bill of materials (BOM) and / or poor power efficiency. Summary of the invention

[0007] In an embodiment, a power converter including a buck-boost converter is disclosed. The buck-boost converter includes: a first input terminal and a second input terminal configured to receive an input voltage; a first output terminal and a second output terminal configured to provide an output voltage; and a transistor, an inductor, a capacitor, a first diode, and a second diode.

[0008] A first terminal of the capacitor is coupled to the first output terminal and a cathode of the second diode, an anode of the second diode is coupled to the first terminal of the inductor, and a second terminal of the capacitor is coupled to the second output terminal and a second terminal of the inductor.

[0009] The transistor comprises a first terminal, a second terminal and a control terminal, wherein the transistor can be switched by applying a control signal between the second terminal and the control terminal.

[0010] The second end of the transistor is coupled to the second end of the inductor.

[0011] Or:

[0012] a first diode is provided with an anode coupled to the first terminal of the inductor and a cathode coupled to the first input terminal, and a first terminal of the transistor is coupled to the second input terminal,

[0013] Or:

[0014] - a first terminal of the inductor is coupled to the first input terminal,

[0015] The first diode is provided with an anode coupled to the second input terminal and a cathode coupled to the first terminal of the transistor.

[0016] The power converter includes a primary side configured to receive input power and coupled to a primary side winding of a transformer, and a secondary side configured to output output power and coupled to a secondary side winding of the transformer.

[0017] In the power converter, a first input terminal of the buck-boost converter is coupled to a first end of an auxiliary winding of a transformer, and a second input terminal of the buck-boost converter is coupled to a second end of the auxiliary winding.

[0018] The above summary is merely a brief overview of some embodiments and should not be construed as limiting in any way, as other embodiments may include different features. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1A is a circuit diagram of a buck-boost converter according to an embodiment, and Figure 1B Shows Figure 1A A variation of the embodiment of the present invention.

[0020] Figure 2 Shows Figure 1AThe relationship between the buck-boost converter and the conventional buck-boost converter.

[0021] Figure 3A is a circuit diagram of a power converter according to an embodiment.

[0022] Figure 3B It is shown Figure 3A Timing diagram of the operation of the power converter.

[0023] Figure 4 is a circuit diagram of a power converter according to an embodiment.

[0024] Figure 5 is a circuit diagram of a power converter according to an embodiment.

[0025] Figure 6 is a circuit diagram of a power converter according to an embodiment. DETAILED DESCRIPTION

[0026] Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings. These embodiments are given by way of example only and should not be construed as limiting.

[0027] Features from different embodiments may be combined to form further embodiments. Variations, details or modifications described with respect to one of the embodiments are also applicable to the other embodiments, and therefore will not be described repeatedly. In the accompanying drawings, identical elements are represented by identical reference numerals.

[0028] Embodiments relate to a power converter including a buck-boost converter. The buck-boost converter can generate an internal supply voltage for the power converter. First, an embodiment of a buck-boost converter that can be used for this purpose will be described, and then an embodiment of a power converter including such a buck-boost converter will be described.

[0029] The embodiments of the buck-boost converter described herein use transistors as switches. The transistor is described as having a first terminal, a second terminal, and a control terminal. Such a transistor is switchable by applying a control signal (voltage or current) between the control terminal and the second terminal. Such a transistor can be operated as a unidirectional switch. In the following embodiments, a MOSFET (metal oxide semiconductor field effect transistor) is used as an example of a switching transistor. In this case, the first terminal corresponds to the drain terminal, the second terminal corresponds to the source terminal, and the control terminal corresponds to the gate terminal. Switching control is achieved by applying a suitable gate-source voltage as a control signal. Note that due to the presence of a body diode, a MOSFET is usually used as a unidirectional switch. This means that in the off state, the MOSFET blocks the current from the first terminal (drain terminal) to the second terminal (source terminal), while the current can still flow in the reverse direction via the body diode via the body diode when the forward voltage of the body diode is exceeded. In the on state, the current can flow in both directions. Although MOSFET is used as an example below, in other embodiments, other types of transistors, such as a bipolar junction transistor (BJT) or an insulated gate bipolar transistor (IGBT), can be used. Such a transistor may also be a unidirectional switch due to the presence of a body diode or a freewheeling diode. In the case of a BJT or an IGBT, the first terminal and the second terminal are the collector terminal and the emitter terminal, respectively, and in the case of a BJT, the control terminal is the base terminal. In addition, in addition to silicon-based transistors, transistors based on other semiconductor materials, such as gallium nitride (GaN)-based transistors, may also be used. In such an implementation, a freewheeling diode may be explicitly provided because the forward voltage of the body diode of a GaN transistor may be too high to prevent current from flowing, which may be required in some applications. In other applications, it may not be necessary to provide an explicit freewheeling diode.

[0030] Unless otherwise indicated, connections or couplings shown in the drawings or described herein are meant to be electrical connections or couplings. Such connections or couplings may be modified, for example, by adding elements or removing elements, as long as the general purpose of the connection or coupling, such as providing a signal, voltage, current, etc., is substantially maintained. This essentially means that connections or couplings shown in the drawings and described herein should be considered functional connections, which may be modified as long as the functionality of the connection is maintained. If no intermediate elements are shown, the connection or coupling may be implemented as a direct connection (e.g., by metal wires, leads, corresponding portions of metal layers in a chip, etc.).

[0031] Embodiments described herein relate to buck-boost converters, and to power converters including such buck-boost converters to provide an internal supply voltage to the power converter. A buck-boost converter is typically a DC-DC converter (i.e., converting a direct current (DC) input voltage to another DC output voltage), wherein the converter can be operated so that the magnitude of the output voltage is greater than, equal to, or less than the magnitude of the input voltage.

[0032] Figure 1A A buck-boost converter 10 according to an embodiment is shown. Figure 1A The buck-boost converter converts the input voltage V IN Converted into output voltage V OUT . Figure 1A The topology is a so-called inverted topology, in which the polarity of the output voltage is opposite to the polarity of the input voltage.

[0033] like Figure 1A As shown, an input voltage V is received at the first input terminal 16A and the second input terminal 16B. IN The output voltage is output between the first output terminal 17A and the second output terminal 17B. Figure 1A , the first output terminal 17A and the second output terminal 17B correspond to the first terminal and the second terminal of the capacitor 15. The buck-boost converter further includes a transistor 11, an inductor 13, a first diode 12 and a second diode 14. For simplicity, the identification of the input terminal and the output terminal is omitted in the following figures, and only the input voltage V is shown. IN and output voltage V OUT or the corresponding voltage.

[0034] The drain terminal of the transistor 11 is coupled to the cathode of the first diode 12, and the source terminal of the transistor 11 is coupled to the second terminal of the inductor 13. The anode of the first diode 12 is coupled to the second input terminal 16B. The first terminal of the inductor 13 is coupled to the first input terminal 16A.

[0035] As already mentioned, a first terminal of the capacitor 15 is coupled to the first output terminal 17A and is also coupled to the cathode of the second diode 14, and the anode of the second diode 14 is coupled to the first terminal of the inductor 13. Furthermore, a second terminal of the capacitor 15 is coupled to the second output terminal 17B and the source terminal of the transistor 11.

[0036] Figure 1B Shows Figure 1A A variation of the buck-boost converter 10 and with Figure 1AThe only difference is the placement of the first diode. A first diode 12A is provided to replace the first diode 12 coupled between the drain terminal of the transistor 12 and the second input terminal. The anode of the first diode 12A is coupled to the first end of the inductor 13, and the cathode of the first diode 12A is coupled to the first input terminal 16A. In addition, the drain terminal of the transistor 11 is coupled to the second input terminal 16B. In addition, Figure 1B The buck-boost converter corresponds to Figure 1A The buck-boost converter of FIG. 1 and the operation are the same. Specifically, Figure 1B The first diode 12A and Figure 1A The first diode 12 has the same function. Therefore, in the embodiment described below, Figure 1A The buck-boost converter can be Figure 1B A buck-boost converter can be used as a replacement for a buck-boost converter, and vice versa.

[0037] exist Figure 1A and Figure 1B In both cases, the source terminal of transistor 11 is directly coupled to output terminal 17B as a negative output voltage terminal. The negative output voltage can be used as a negative output voltage V OUT Thus, since the source terminal of transistor 11 is then referenced to ground, it can be controlled by such a controller.

[0038] In the description Figure 1A Before operating the buck-boost converter, refer to Figure 2 , will describe Figure 1A The buck-boost converter in Figure 2 The relationship of a conventional buck-boost converter is shown in row (a). Figure 1A The buck-boost converter in Figure 2 Note that in rows (a) and (b), the input voltage V IN On the left, and the output voltage V OUT on the right, while in rows (c) and (d), Figure 1A Similarly, the input voltage V IN On the right side, and the output voltage V OUT On the left side.

[0039] exist Figure 2 In the conventional buck-boost converter of row (a), an output voltage is also provided across capacitor 15, and inductor 13 is provided. Transistor 11 is provided between the ends of inductor 13 and the input voltage. Note that in row (a), the source terminal is coupled to output terminal 17B only via diode 14', rather than Figure 1A and Figure 1BThe cathode of the diode 14' and the drain terminal of the transistor 11 are coupled to the same end of the inductor 13.

[0040] In order to get Figure 1A The buck-boost converter of row (a) is shown in FIG. 1 , where the first diode 14' is "moved" to the position of the diode 14, i.e., so that the anode of the diode 14 is now coupled to the other end of the inductor 13 compared to row (a). In this way, the source terminal of the transistor 11 is directly coupled to the output terminal 17B. From row (b) to row (c), the representation of the circuit is only rotated by 180° without changing the circuit. From row (c) to row (d), in order to handle the AC input voltage, the first diode 12 is added. Specifically, at the input voltage V IN When the first diode 12 (or the first diode 12) is negative, the body diode 20 of the transistor 11 does not prevent the current from flowing from the first input terminal 16A to the second input terminal 16B via the inductor 13 and the transistor 11 when the transistor 11 is in the off state. Figure 1B 12B), still prevents this current from flowing. It should be noted that the body diode 20 is only explicitly shown in some of the drawings where it helps to illustrate the operation, but is a general characteristic of transistors, for example in the case of a MOSFET for transistor 11.

[0041] exist Figure 1A In the buck-boost converter of row (d), since the source terminal is directly coupled to the output terminal 17A, the transistor 11 can be powered by the gate driver to output the voltage V OUT Or based on the output voltage V OUT To control, the output voltage V OUT For example, it is used as a supply voltage in some applications. Figure 1A The driver for transistor 11 in can be based on this supply voltage without the need for an isolation driver.

[0042] besides, Figure 1A The operation of the buck-boost converter is similar to Figure 2 The operation of a conventional buck-boost converter in row (a) is shown in FIG. 1 . When the corresponding transistor 11 is turned on, the input voltage is connected to Figure 1A The inductor 13 is connected to the capacitor 15, wherein the diode 12 allows current to flow in only one direction, thereby effectively decoupling the charging of the inductor 13 from the energy from the capacitor 15. At this stage, the capacitor 15 receives the output voltage V OUT When the transistor 11 is turned off, the current in the inductor keeps flowing, thus changing the voltage level across the inductor and enabling energy to be transferred from the inductor 13 to the capacitor 15 via the diode 14.

[0043] Depending on the duty cycle (the time the transistor 11 is on compared to the time the transistor 11 is off), the output voltage V OUT The amplitude can be greater than, equal to, or less than the input voltage V IN In some embodiments, the control entity ( Figure 1A The output voltage V may be measured by any conventional means, such as using a resistor divider (not shown). OUT , and controls transistor 11 accordingly. In other embodiments, the input voltage V IN may be known, for example, by design, and the duty cycle may be fixed accordingly. In other embodiments, the regulation may be based on the input voltage V IN and indicates the input voltage V of the buck-boost converter IN any other signal to adjust the output voltage, because for a given inductance value of capacitor 15 and inductor 13, the input voltage V IN With the output voltage V OUT The relationship between is a function of the duty cycle of switch 11. Figure 3A The power converter 30 is shown in FIG. Figure 1A The buck-boost converter generates the supply voltage V VCC .

[0044] The power converter is shown as a schematic flyback converter, which converts the input voltage V in2 (Don't Figure 1A , Figure 1B and Figure 2 The input voltage V IN confusion) into an output voltage V out2 (Also do not Figure 2 , Figure 1A and Figure 1B The output voltage V OUT This power converter is only an example, and Figure 1A (or Figure 1B ) can typically be used in a power converter having a transformer and an auxiliary winding for galvanic isolation. Figure 3A The power converter includes a transformer 32 providing galvanic isolation 32D between the primary side and the secondary side. Figure 3A In the simplified representation of FIG. 3 , the switch 31 is coupled to the primary winding 32A. The secondary winding 32B is coupled to the output capacitor 34 via the rectifier diode 33. The output voltage is provided across the capacitor 34. P :N S is the winding ratio between the primary side winding 32A and the secondary side winding 32B.

[0045] By closing the switch 31, energy is transferred from the primary side into the transformer (charging), and by opening the switch 31, energy is transferred from the transformer to the secondary side (discharging), and the output voltage V is generated in a conventional manner. out2 The operation of the switch 31 is controlled by the controller 35 .

[0046] Figure 3A The representation of a flyback converter is only a schematic example, and any kind of power converter with a transformer for galvanic isolation and operated in a conventional manner may be used, such as an asymmetric half-bridge flyback converter with a half-bridge switch arrangement on the primary side. For example, a synchronous rectifier may also be used instead of the rectifier diode 33. Furthermore, feedback from the secondary side to the primary side may be used in any conventional manner. Since the design and operation of such a converter is known to a person skilled in the art, no further description will be given here.

[0047] Figure 3A The flyback converter uses reference Figure 1A The buck-boost converter discussed is used to provide a supply voltage V for powering the controller 35, for example. VCC Therefore, V VCC Corresponds to Figure 1A The output voltage V OUT .

[0048] In order to provide an input voltage to the buck-boost converter, the transformer 32 includes an auxiliary winding 32C. The auxiliary winding 32C provides a voltage V aux The polarity of the auxiliary winding 32C (via Figure 3A The point indicated in the middle is selected to be the same polarity as the primary winding 32A and opposite polarity to the secondary winding 32B, so that the voltage V VCC The polarity corresponds to Figure 3A Medium V in2 and V out2 In this case, as will be explained below, an available negative voltage (depending on V aux The input voltage is in the direction of the arrow, and this voltage is proportional to V out2 If the polarity of the auxiliary winding 32 is modified, the input voltage of the buck-boost converter will be proportional to V in2 Proportional and can be used for the charging phase of the transformer. Both possibilities can be used in embodiments.

[0049] The transistor 11 of the buck-boost converter may also be controlled by a controller 35. In this respect, the controller 35 need not be a single entity, but may comprise several entities, such as a first entity for controlling the operation of the switch 31 and the operation of the flyback converter in general, and a second entity for controlling the transistor 11. Such entities may be based on different technologies, such as a silicon-based entity and a GaN-based entity.

[0050] Since the source terminal of transistor 11 is coupled to the output side of the buck-boost converter, the control entity for transistor 11 does not need to be isolated, but can be controlled by V VCC At startup, capacitor 15 can be charged directly from the main power supply through different paths (for example, including resistors and / or depleted batteries) until the startup voltage is reached. Capacitor 15 can then provide sufficient energy until V is established. VCC Any conventional activation technique may be used in this regard.

[0051] exist Figure 3A In an embodiment of the present invention, during the transformer discharge phase of the flyback converter, Figure 3A In the configuration, the controller 35 only operates when the input voltage V aux The buck-boost converter is operated only when the polarity of is negative, because at this time the voltage V provided by the auxiliary winding 32C is aux has the correct negative polarity to be used as the input voltage of the buck-boost converter.This can be achieved by controlling the switch 31 and the transistor 11 by the same controller (eg, controller 35). Figure 3B Such control is further illustrated in . Figure 3B The control signal ctrl1 for controlling the switch 31 and the primary side current I PRI , secondary side current I SEC , Auxiliary voltage V for powering the buck-boost converter aux 1 and an example signal curve of the control signal ctrl2 controlling transistor 11. As shown, transistor 11 is turned on and off only during the discharge phase between time t1 and t2, wherein switch 31 is turned off and V aux is negative. Figure 3A Configuration, V aux Positive value of ( Figure 3B Before t1 and after t2) has an amplitude of V in2 (N aux / N P ), where N aux / N P is the winding ratio between the auxiliary winding 32C and the primary winding 32A, and V aux The negative value (between t1 and t2) has a magnitude of V out2(N aux / N S ), where N aux / N S is the winding ratio between the auxiliary winding 32C and the secondary winding 32B. If the polarity of the auxiliary winding is reversed as described above, the transistor 11 will only operate during the charging phase, because V aux will be negative again.

[0052] Figure 4 A power converter 40 according to another embodiment is shown, in which the buck-boost converter may be operated continuously, rather than just during the transformer discharge phase of the flyback converter. The power converter 40 is a variation of the power converter 30 of FIG. 3 , and only the differences will be described below.

[0053] In the power converter 40, Figure 1A Compared to the buck-boost converter of FIG. 1 , as shown, a capacitor 42 is additionally provided. The capacitor 42 acts as a buffer to provide a continuous input voltage to the buck-boost converter, because the capacitor 42 acts as an energy storage device, and the first diode 12 in this case also prevents energy from flowing back from the capacitor 42 to the auxiliary winding 32C and ensures that the capacitor 42 is only charged when the voltage provided by the auxiliary winding 32C has the "correct" negative polarity for the operation of the buck-boost converter, that is, only when there is Figure 4 The winding polarity shown is charged during the discharge phase of the transformer.

[0054] exist Figure 4 In the embodiment of the present invention, by providing capacitor 42, the operation of the buck-boost converter does not have to be limited to the voltage V aux is negative, the buck-boost converter can operate all the time. Figure 4 In the embodiment, as shown, a further diode 41 may be provided between the capacitor 42 and the transistor 11, but may also be omitted.

[0055] Simulations have shown that Figure 4 The buck-boost converter in the embodiment can provide a wide range of stable voltage V for the auxiliary winding 32. VCC Or for example about 12 V, for example in the range from 5 V to 50 V. For example, in this case, for a voltage at the auxiliary winding of 50 V, the duty cycle of the transistor 11 may be about 7% at 40 kHz, and for a voltage at the auxiliary winding of 5 V, the duty cycle may be about 80%.

[0056] Figure 5 FIG. 5 shows a power converter 50 according to another embodiment. The power converter 50 is based on the power converter 30 of FIG. 3 . Compared with FIG. 3 , Figure 1B The power converter of is used with diode 12B. As mentioned before, this is independent of other modifications and can also be done in other embodiments. In addition, a third diode 51 couples the auxiliary winding, ie the input of the buck-boost converter, to the terminal of capacitor 15.

[0057] exist Figure 5 In the embodiment, in V aux When the input voltage V in2 high enough, for example if V in2 is of the order of 400 V, the capacitor 15 is connected to the positive auxiliary winding voltage V via the diode 51 and the body diode 20 of the transistor 11. aux Note that in order to achieve this charging, Figure 5 In the implementation mode, the following is used: Figure 1B The diode 12B in Figure 1A The diode 12 will prevent charging. During the discharge phase of the transformer, V aux is negative (corresponding to Figure 1B The buck-boost converter can be used to charge the capacitor 15 to generate the output voltage V VCC , especially if V in2 is not high enough to generate enough auxiliary winding voltage to charge capacitor 15 directly via diode 50. In other embodiments, additional diodes 41 and capacitors 42 may be provided in power converter 50. In addition, transistor 11 does not have a voltage that enables the positive V AUX In the case of a body diode for charging the capacitor 15, for example in the case of a GaN transistor with a high forward voltage of the body diode, an additional freewheeling diode can be provided.

[0058] In some cases with high V in2 In applications where the capacitor 15 is charged via the diode 51, it may be problematic, resulting in a high voltage V provided by the auxiliary winding 32C. AUX (For example, V AUX Significantly exceeds the required voltage V VCC ). Figure 6 The power converter 60 is shown in the form of Figure 5 A variation of the embodiment of Figure 6 In the power converter 60 of FIG. 1 , the auxiliary winding is split or has an intermediate contact between the winding portions 32C1 and 32C2. The buck-boost converter is coupled to the “full” auxiliary winding (32C1 plus 32C2) to receive the voltage V AUX2 As input voltage, with Figure 5The diode 61 corresponding to the diode 51 directly charging the capacitor 15 is coupled to the intermediate node between the winding parts 32C1 and 32C2 to receive the voltage V AUX1 Therefore, based on the winding ratio of the winding parts 32C1, 32C2 and the winding ratio N between the primary winding 32A and the secondary winding 32B P :N S To limit the voltage V AUX1 .

[0059] As a numerical example, the winding ratio N P :N S It may be 70: 10. The winding ratio of the portion 32C1 to the portion 32C2 of the auxiliary winding may be 7:3, so that the total number of turns of the auxiliary winding (32C1 plus 32C2) is equal to the number of turns of the secondary winding 32B.

[0060] At input voltage V in2 When the voltage V at the auxiliary winding portion 32C2 is 400V, AUX1 will be 400V x 3 / 70 = 17.14V. Subtracting the forward voltage drop diode 61 and the transistor body diode 20, a supply voltage of approximately 15V is available without buck-boost operation. If V in2 is lower, the buck-boost converter can take over V VCC In this example, the entire auxiliary winding (parts 32C1 to 32C2) has the same number of turns as the secondary winding 32B, which causes a voltage similar to V out2 The output voltage range is V AUX2 Over the full range of USB-PD voltages V from approximately 5V to approximately 48V out2 This means that the voltage range V can be increased by using a buck-boost converter to step down or step up the voltage. AUX2 Converted to a power supply voltage of approximately 15V VCC The above numbers are examples only, and other numbers for windings and winding ratios may be used. For example, in some embodiments, a secondary winding and / or an auxiliary winding having only one turn may be used.

[0061] It should be noted that although in the above embodiment, the auxiliary winding 32C is shown on the primary side of the transformer 32, in other embodiments, an auxiliary winding on the secondary side may also be used, for example to provide power to a secondary side controller.

[0062] The embodiments discussed above may have lower area requirements and / or lower bill of materials (BOM) compared to conventional solutions. Furthermore, a control entity such as controller 35 requires only a single terminal to control the buck-boost converter, namely control transistor 11 .

[0063] Some embodiments are defined by the following examples:

[0064] Example 1. A power converter comprising:

[0065] a primary side configured to receive input power and coupled to a primary side winding of a transformer,

[0066] a secondary side configured to output output power and coupled to a secondary side winding of the transformer, and

[0067] Buck-boost converter, including:

[0068] a first input terminal and a second input terminal configured to receive an input voltage,

[0069] a first output terminal and a second output terminal configured to provide an output voltage,

[0070] a transistor, an inductor, a capacitor, a first diode and a second diode,

[0071] wherein a first terminal of the capacitor is coupled to the first output terminal and the cathode of the second diode, an anode of the second diode is coupled to the first terminal of the inductor, and a second terminal of the capacitor is coupled to the second output terminal and the second terminal of the inductor, wherein the transistor includes a first terminal, a second terminal and a control terminal,

[0072] The transistor can be switched by applying a control signal between the second terminal and the control terminal.

[0073] The second end of the transistor is coupled to the second end of the inductor.

[0074] Among them, either:

[0075] a first diode is provided with an anode coupled to the first terminal of the inductor and a cathode coupled to the first input terminal, and a first terminal of the transistor is coupled to the second input terminal,

[0076] or

[0077] - A first terminal of the inductor is coupled to the first input terminal

[0078] The first diode is provided with an anode coupled to the second input terminal and a cathode coupled to the first terminal of the transistor,

[0079] The first input terminal of the buck-boost converter is coupled to the first terminal of the auxiliary winding of the transformer, and the second input terminal of the buck-boost converter is coupled to the second terminal of the auxiliary winding.

[0080] Example 2. The power converter according to Example 1 further includes a controller configured to control the transistor so that the buck-boost converter generates an output voltage based on the input voltage.

[0081] Example 3. The power converter according to Example 1 or 2, further comprising: a power converter controller coupled to the first output terminal and the second output terminal of the buck-boost converter to be powered by the output voltage of the buck-boost converter.

[0082] Example 4. The power converter of Example 2 or Example 3, wherein the controller is a power converter controller.

[0083] Example 5. The power converter according to any one of Examples 1 to 4, further comprising:

[0084] another capacitor, wherein a first end of the another capacitor is coupled to the first input terminal, the first end of the inductor and the anode of the second diode, a second end of the another capacitor is coupled to the first end of the transistor and the cathode of the first diode, and wherein the anode of the first diode is coupled to the second input terminal.

[0085] Example 6: The power converter according to Example 5, further comprising a third diode, wherein an anode of the third diode is coupled to the second end of the further capacitor and a cathode of the third diode is coupled to the first end of the transistor.

[0086] Example 7. The power converter of any of Examples 1 to 6, further comprising a fourth diode, wherein an anode of the fourth diode is coupled to the first input terminal and a cathode of the fourth diode is coupled to the first terminal of the capacitor.

[0087] Example 8. The power converter according to any one of Examples 1 to 7,

[0088] A fifth diode is also included, wherein an anode of the fifth diode is coupled to the third input terminal of the buck-boost converter, and a cathode of the fifth diode is coupled to the first terminal of the capacitor.

[0089] Example 9. The power converter of Example 8, wherein the third input terminal of the buck-boost converter is coupled to an intermediate terminal of the auxiliary winding between the first terminal and the second terminal of the auxiliary winding.

[0090] Example 10. A power converter according to Example 9, wherein the auxiliary winding is on the primary side of the transformer, wherein the ratio of the number of windings between the middle end and the second end of the auxiliary winding to the number of windings of the primary side winding is selected so that for a predefined nominal input voltage, the fifth diode provides a desired output voltage to the capacitor.

[0091] Example 11. The power converter of any of Examples 1 to 10, wherein the transistor is a MOSFET transistor, the first terminal of the transistor is a drain terminal, and the second terminal of the transistor is a source terminal.

[0092] Although specific embodiments have been shown and described herein, it will be appreciated by those of ordinary skill in the art that various alternative implementations and / or equivalent implementations may be used to replace the specific embodiments shown and described without departing from the scope of the present invention. The present application is intended to cover any adaptation or variation of the specific embodiments discussed herein. Therefore, the present invention is intended to be limited only by its claims and their equivalents.

Claims

1. A power converter, comprising: a primary side configured to receive input power and coupled to a primary side winding (32A) of a transformer (32), a secondary side configured to output output power and coupled to a secondary side winding (32B) of the transformer (32), and A buck-boost converter (10) comprising: is configured to receive an input voltage (V IN ), a first input terminal (16A) and a second input terminal (16B), is configured to provide an output voltage (V OUT ,V vcc ) a first output terminal (17A) and a second output terminal (17B), a transistor (11), an inductor (13), a capacitor (15), a first diode (12, 12B) and a second diode (14), wherein the first end of the capacitor (15) is coupled to the first output end (17A) and the cathode of the second diode (14), the anode of the second diode (14) is coupled to the first end of the inductor (13), and the second end of the capacitor (15) is coupled to the second output end (17B) and the second end of the inductor (13), wherein the transistor (11) comprises a first end, a second end and a control end, The transistor can be switched by applying a control signal between the second terminal and the control terminal. The second end of the transistor (11) is coupled to the second end of the inductor (13). Among them, either: - the first diode (12B) is configured to be coupled to an anode of a first end of the inductor (13) and to a cathode of the first input terminal (16A), and a first end of the transistor (11) is coupled to the second input terminal (16B), or - a first end of the inductor (13) is coupled to the first input end (16A), The first diode (12) is configured to be coupled to an anode of the second input terminal (16B) and to be coupled to a cathode of the first terminal of the transistor (11), The first input terminal (16A) of the buck-boost converter (10) is coupled to the first end of the auxiliary winding (32C) of the transformer (32), and the second input terminal (16B) of the buck-boost converter (10) is coupled to the second end of the auxiliary winding (32C).

2. The power converter according to claim 1, further comprising a controller (35) configured to control the transistor (11) so that the buck-boost converter (10) is based on the input voltage (V IN ) generates the output voltage (V OUT , V VCC ).

3. The power converter according to claim 1 or 2, further comprising a controller (35), wherein the controller (35) is coupled to the first output terminal (17A) and the second output terminal (17B) of the buck-boost converter (10) to generate an output voltage (V OUT 、V VCC )powered by.

4. A power converter according to claim 2 or 3, wherein: The controller (35) is a power converter controller.

5. The power converter according to any one of claims 1 to 4, further comprising: another capacitor (42), wherein a first end of the another capacitor (42) is coupled to the first input terminal (16A), the first end of the inductor (13) and the anode of the second diode (14), a second end of the another capacitor (42) is coupled to the first end of the transistor (11) and the cathode of the first diode (12), and wherein the anode of the first diode (12) is coupled to the second input terminal (16B).

6. The power converter according to claim 5, further comprising a third diode (41), wherein An anode of the third diode is coupled to the second end of the other capacitor (42), and a cathode of the third diode (41) is coupled to the first end of the transistor (11).

7. The power converter according to any one of claims 1 to 6, further comprising a fourth diode (51), wherein: An anode of the fourth diode (51) is coupled to the first input terminal (16A), and a cathode of the fourth diode (51) is coupled to the first terminal of the capacitor (15).

8. The power converter according to any one of claims 1 to 7, Also included is a fifth diode (61), wherein: An anode of the fifth diode (61) is coupled to the third input terminal of the buck-boost converter, and a cathode of the fifth diode (61) is coupled to the first terminal of the capacitor (15).

9. The power converter according to claim 8, wherein: The third input terminal of the buck-boost converter is coupled to an intermediate terminal of the auxiliary winding (32C) between the first terminal and the second terminal of the auxiliary winding (32C).

10. The power converter according to claim 9, wherein: The auxiliary winding (32C) is on the primary side of the transformer (32), wherein the ratio of the number of windings between the middle end and the second end of the auxiliary winding to the number of windings of the primary side winding is selected so that for a predefined nominal input voltage, the fifth diode (61) provides a desired output voltage to the capacitor (15).

11. The power converter according to any one of claims 1 to 10, wherein: The transistor (11) is a MOSFET transistor, the first terminal of the transistor (11) is a drain terminal, and the second terminal of the transistor (11) is a source terminal.

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