Apparatus and method for a controllable network in a multi-stage power conversion system for varying power transfer between stages

Abstract

This document discloses an apparatus and method for using a controllable network in a multi-stage power conversion system to modify inter-stage power delivery. By using a controllable network (111-113) within a first power converter stage (102), the intermediate power delivered to a subsequent or second power converter stage (104) can be modified, allowing the multi-stage power conversion system (100) to respond to full-load steps while providing improved light-load power conversion efficiency. A power estimation circuit (122) within the second power converter stage (104) can provide control signals (C1-CN) to each of the controllable networks (111-113); the controllable networks (111-113) can then provide network signals (S1, S2) to control the intermediate power delivered to the second power converter stage (104).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 779,352, filed on December 13, 2018, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a controllable network in a multi-stage power conversion system for varying inter-stage power transfer, and more particularly to a controllable network in a multi-stage alternating current (ac) to direct current (dc) power conversion system for regulating the power delivered to a series inductor-inductor capacitor (LLC) converter. Background Art

[0004] Many electronic devices, such as cell phones, laptop computers, etc., are powered by direct current (DC) power obtained from a power supply. Conventional wall sockets typically deliver high voltage alternating current (AC) power that needs to be converted to regulated DC power in order to be used as a power source for consumer electronic devices. In some applications, a power conversion system may cascade one or more power converter stages, including a first stage with power factor correction (PFC) and a second stage with a switch-mode power converter. Switch-mode power converters are commonly used to convert high voltage AC power to regulated DC power due to their high efficiency, small size, and light weight.

[0005] One type of switch-mode power converter is a resonant converter, which includes a resonant circuit (e.g., an inductor and a capacitor) as part of a power module. The resonant circuit can advantageously improve power conversion efficiency by utilizing zero-current switching and / or zero-voltage switching.

[0006] A subset of resonant converters - series inductor-inductor-capacitor (LLC) converters - use a resonant circuit with two inductors and one capacitor connected in series to form an LLC resonant circuit. Typically, LLC converters are controlled so that the power switches perform zero voltage switching. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Non-limiting and non-exhaustive embodiments of a controllable network to vary inter-stage power transfer in a multi-level power conversion system are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

[0008] Figure 1A multi-level power conversion system for delivering output power to a load in accordance with the teachings herein is illustrated.

[0009] Figure 2A A first power converter stage having a controllable network according to an embodiment is illustrated.

[0010] Figure 2B A first power converter stage having a controllable network according to another embodiment is illustrated.

[0011] Figure 3A A second power converter stage according to an embodiment is illustrated.

[0012] Figure 3B A second power converter stage according to another embodiment is illustrated.

[0013] Figure 3C A second power converter stage according to another embodiment is illustrated.

[0014] Figure 3D A second power converter stage according to another embodiment is illustrated.

[0015] Figure 4A A circuit implementation of a burst mode detection circuit for detecting a burst mode according to a first embodiment is illustrated.

[0016] Figure 4B A circuit implementation of a burst mode detection circuit for detecting a burst mode according to a second embodiment is illustrated.

[0017] Figure 5A Switching waveforms during continuous conduction mode according to an embodiment are illustrated.

[0018] Figure 5B Switching waveforms during a burst mode according to an embodiment are illustrated.

[0019] Figure 5C Switching waveforms during continuous conduction mode according to another embodiment are illustrated.

[0020] Figure 5D Switching waveforms during a burst mode according to another embodiment are illustrated.

[0021] Fig. 6A Signal waveforms during a load step according to an embodiment are illustrated.

[0022] Figure 6B Signal waveforms during a load step according to another embodiment are illustrated.

[0023] Figure 7Plots comparing efficiency versus relative output power according to an embodiment of a multi-stage power conversion system are shown.

[0024] Figure 8 A conceptual flow diagram for controlling intermediate power delivered to a power converter stage using a controllable network according to an embodiment is illustrated.

[0025] In all several views of the accompanying drawings, corresponding reference characters indicate corresponding parts. It will be appreciated by the technician that the elements in the accompanying drawings are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the sizes of some elements in the accompanying drawings may be exaggerated relative to other elements to help improve the understanding of the various embodiments of the teachings of this article. In addition, common but easily understood elements that are useful or necessary in commercially feasible embodiments are generally not depicted so as to less hinder the viewing of these various embodiments of the controllable network for changing inter-stage power transfer in a multi-stage power conversion system. DETAILED DESCRIPTION

[0026] In the following description, many specific details are set forth to provide a thorough understanding of the controllable network for changing inter-stage power transfer in a multi-stage power conversion system. However, it will be apparent to one of ordinary skill in the art that the specific details need not be employed to practice the teachings herein. In other cases, well-known materials or methods are not described in detail to avoid obscuring the present disclosure.

[0027] References throughout this specification to "one embodiment", "anembodiment", "one example" or "an example" mean that specific features, structures or characteristics described in conjunction with the embodiment or example are included in at least one embodiment of a controllable network for varying inter-stage power transfer in a multi-stage power conversion system. Therefore, the phrases "in one embodiment", "in one embodiment", "one example" or "an example" appearing in various places throughout this specification do not necessarily all refer to the same embodiment or example. In addition, specific features, structures or characteristics may be combined in any suitable combination and / or sub-combination in one or more embodiments or examples. Specific features, structures or characteristics may be included in an integrated circuit, an electronic circuit, a combinational logic circuit, or other suitable components that provide the described functionality. In addition, it should be understood that the drawings provided herewith are for the purpose of explanation to those of ordinary skill in the art, and that the drawings are not necessarily drawn to scale.

[0028] In the context of the present application, when the transistor is in an "off state" or "disconnected", the transistor blocks current and / or substantially does not conduct current. In contrast, when the transistor is in an "on state" or "conducting", the transistor is able to conduct current significantly. For example, in one embodiment, the high voltage transistor comprises an N-channel metal oxide semiconductor (NMOS) field effect transistor (FET), wherein the high voltage is supported between a first terminal, i.e., a drain, and a second terminal, i.e., a source. In some embodiments, an integrated controller circuit can be used to drive a power switch when regulating the energy provided to a load. In addition, for the purposes of the present disclosure, "ground" or "ground potential" refers to a reference voltage or potential relative to which all other voltages or potentials of an electronic circuit or an integrated circuit (IC) are defined or measured.

[0029] As discussed above, a multi-stage power conversion system may use more than one power converter stage to implement a power conversion system (e.g., a power supply). In a multi-stage power conversion system, a first power converter stage may receive an AC input power and provide intermediate power to a subsequent stage connected in cascade. For example, a first power converter stage may include a power factor correction (PFC) circuit to pre-regulate the power delivered to a second power converter stage. The PFC circuit may condition and shape an AC (ac) rectified signal to advantageously improve (i.e., increase) the overall power factor.

[0030] The second power converter stage can convert the intermediate power into output power. For example, as described above, the second stage can include a switch mode power converter. One type of switch mode power converter is a resonant converter. The resonant converter can be used to advantageously reduce switching losses by utilizing zero current switching (ZCS) and / or zero voltage switching (ZVS).

[0031] As also mentioned above, LLC converters are a subset of resonant converters. LLC converters can be controlled to operate at a switching frequency in order to utilize zero voltage switching. Zero voltage switching (ZVS) is a soft switching characterized in that the on and off transitions of a switch (e.g., a power field effect transistor (FET) or semiconductor device) occur when the voltage across the switch (e.g., the power FET drain-source voltage) is zero or substantially close to zero. In this way, voltage-related switching losses can be minimized or substantially zero during the switching transitions, thereby reducing switching losses.

[0032] The operation of the power converter stage can depend on the load conditions. For example, the switching frequency of an LLC converter operating in continuous conduction mode can depend on the output load conditions. Typically, LLC converters operate above resonance so that as the output load increases, the switching frequency decreases to meet the higher power demand.

[0033] At light loads, higher frequency continuous mode operation in an LLC converter may be limited; therefore, once a minimum load threshold level has been detected, a light load mode may be utilized to more efficiently provide power. For example, an LLC converter may have a detection circuit capable of determining when the output power demand reaches a minimum power level. Detection of a light load threshold condition may be used to determine when to transition from operating in continuous mode to operating in burst mode.

[0034] During the burst mode, the LLC converter can switch at a fixed frequency within a short duration when necessary to maintain the output voltage level. Between these short durations, switching can be prohibited. Controlling the switch in this way in a switch mode power stage is generally referred to as "burst" and / or "burst mode". In a multi-stage power conversion system, often during a light load (e.g., burst mode and / or a burst mode on a second power converter) condition, the first power converter stage in front can be temporarily disabled to improve the overall system efficiency. When the first power converter stage is temporarily disabled, the intermediate power for the second power converter stage (e.g., LLC converter) can be provided by a capacitor (e.g., a bulk capacitor). The size of the capacitor, which is generally referred to as a hold-up capacitor, can be selected so that enough power is delivered to the second power converter stage (e.g., LLC converter). The time period during which the first power converter stage is temporarily disabled can be referred to as "hold" and / or "ride-through", and the amount of time during which power is provided only by the bulk capacitor can be referred to as the "hold" time and / or "ride-through" time.

[0035] Turning off the first power stage in front to improve overall system efficiency may become a problem. The power output power capacity of the second converter is usually reduced at a lower operating input voltage (output from the first converter). For example, a load step may occur when the load changes from a light load (e.g., burst mode) to a medium or heavy load condition. When a load step suddenly appears at the output of a multi-stage power conversion system, there is a delay time during which the first power converter stage (i.e., PFC circuit) must be restarted (i.e., enabled). During this time, the output voltage remains much lower, and it takes time for it to rise sufficiently to allow the second converter to meet the output power demand. Due to the time delay in enabling the first power converter stage, the multi-stage power conversion system is generally unable to respond quickly enough to complete a full load step from burst mode to maximum load (i.e., one hundred percent of the maximum output power level).

[0036] Therefore, there is a need for a multi-level power conversion system that allows for improved efficiency during light and / or burst mode conditions while also being able to respond to full (one hundred percent) load steps.

[0037] Disclosed herein are devices and methods for changing a controllable network for inter-stage power transfer in a multi-stage power conversion system. By using a controllable network within a first power converter stage, the intermediate power delivered to a subsequent or second power converter stage can be changed so that the multi-stage power conversion system can respond to full load steps while providing improved light load power conversion efficiency. A power estimation circuit within a second power converter stage can provide a control signal to each of the controllable networks; the controllable network can in turn provide a network signal (e.g., voltage and / or current) to control the intermediate power delivered from the first stage to the second power converter stage.

[0038] Figure 1 A multi-level power conversion system 100 is illustrated for delivering output power to a load 106 according to the teachings herein. The multi-level power conversion system 100 includes a first power converter stage 102, a second power converter stage 104, and a holding capacitor 103. The first power converter stage 102 is electrically connected in cascade with the second power converter stage 104, and can convert the AC input power (i.e., the AC input voltage V AC and AC input current I AC ) is converted into intermediate power. As shown, the first power converter stage 102 can be electrically cascaded with the second power converter stage 104 and can provide the intermediate power to the second power converter stage 104 at an intermediate voltage V2 relative to the DC ground GND. The holding capacitor 103 can be used to store energy and maintain the intermediate voltage V2 during the ride-through period. The second power converter stage 104 can convert the intermediate power (i.e., the intermediate voltage V2 and the intermediate current I2) received at its input into output power (i.e., the output voltage V OUT and output current I OUT ).

[0039] The output power may be delivered to the load 106, and the amount of the output power may depend on the load condition. The load condition may be determined by a power demand criterion. For example, a light load condition may include an output current I OUT And / or the output power drops below a standard threshold level (e.g., less than 10 percent of the maximum rating). In addition, the nominal load condition may include the output current I OUT and / or conditions where the output power is above the standard threshold.

[0040] The first power converter stage 102 includes an AC rectifier 108, a capacitor 107, a first stage power circuit 110, and a controllable network 111-113. The AC rectifier 108 includes four diodes D1-D4 connected in a diode bridge to provide a voltage supply voltage VAC and AC input current I AC ) for rectification. The cathodes of diodes D1 and D2 are electrically connected to capacitor 107 and to the input of the first stage power circuit 110; the anodes of diodes D3 and D4 are electrically connected to the DC ground GND. In this way, the AC rectified power (i.e., the rectified AC input voltage V1) can be referenced to the DC ground GND, and capacitor 107 can be used to filter ripple and / or electromagnetic interference (EMI).

[0041] In addition, if Figure 1 As shown in , the first stage power circuit 110 is electrically connected to the DC ground GND, and it receives the rectified AC input power (i.e., the rectified AC input voltage V1 and the rectified AC input current I1) from the AC rectifier 108. In addition, the output of the first stage power circuit 110 is electrically connected to the input of the second power converter stage 104. The second power converter stage 104 receives the intermediate power (i.e., the intermediate voltage V2 and the intermediate current I2) converted by the first stage power circuit 110. The holding capacitor 103 is connected at the output of the first stage power circuit 110 to store energy, and can be used to maintain the intermediate voltage V2 during the ride-through period. In addition, the intermediate power can be a direct current (dc) power.

[0042] like Figure 1 As shown in , the second power converter stage 104 also includes an output connected to the load 106 and can be connected to the DC ground GND and the isolation ground RTN. In this way, the output power delivered to the load 106 can be isolated (e.g., galvanically isolated) from the intermediate power (i.e., the intermediate voltage V2 and the intermediate current I2). Although Figure 1 A configuration with an isolated ground RTN is shown, but other configurations are possible.For example, in some configurations, the second power converter stage 104 may be configured to use a single (non-isolated) ground.

[0043] In addition, the second power converter stage 104 includes a second stage power circuit 120. The second stage power circuit 120 includes a power estimation circuit 122, which can generate control signals C1-C3, -CN based on the load conditions. In some embodiments, the control signals C1-C3, CN can be digital signals and can have load-dependent logic values ​​(i.e., logic high and / or logic low) depending on one or more load conditions. For example, if the power estimation circuit 122 detects that the output power at the load 106 (i.e., the output voltage V OUT and output current I OUT) satisfies a light load condition, one or more of the control signals C1-C3, CN may have a logic high (or low) value. Alternatively, if the power estimation circuit 122 detects that the load is operating under a nominal (non-light load) condition, one or more of the control signals C1-C3, CN may have a logic low (or high) value. In other embodiments, the control signals C1-C3, CN may be analog signals to provide analog control based on the output power level.

[0044] The second power converter stage 104 provides one or more of the control signals C1 - C3 , CN to the first power converter stage 102 where they may be applied to the controllable networks 111 - 113 to regulate the intermediate power (ie, the intermediate voltage V2 and the intermediate current I2 ).

[0045] The controllable networks 111-113 can receive signals (e.g., rectified AC input voltage V1, intermediate voltage V2, rectified AC input current I1, intermediate current I2) from the first power converter stage 102 and / or sample the signals when controlling the intermediate power (i.e., intermediate voltage V2 and intermediate current I2). In addition, the controllable networks 111-113 can adjust the intermediate power in response to one or more of the control signals C1-C3, CN. For example, the controllable network 111 receives the control signal C1 and is electrically connected at the output of the first stage power circuit 110. The controllable network 111 can sample the intermediate voltage V2 and provide a network signal S1, which can be used by the first stage power circuit 110 to regulate the intermediate power (e.g., intermediate voltage V2). By using the control signal C1 to adjust the network signal S1, the multi-stage power conversion system 100 can adjust (i.e., change) the intermediate power based on the load condition. Similarly, as Figure 1 As illustrated in FIG. 1 , the controllable network 112 may be used to adjust the intermediate power by sampling the rectified AC input voltage V1 and providing a network signal S2 to the first stage power circuit 110 based on a control signal C2 .

[0046] The controllable network 113 can also be configured to control the intermediate power in response to the control signal C3. The controllable network 113 is electrically connected between the input terminal 103 and the AC rectifier, at the anode of the diode D2 and the cathode of the diode D4. Based on the control signal C3, the controllable network 113 can be used to control and / or adjust the rectified AC input power (i.e., the rectified AC input voltage V1 and the rectified AC input current I1). By using the control signal C3 to adjust the rectified AC input power, the multi-stage power conversion system 100 can adjust the intermediate power and / or the way (e.g., conversion efficiency) of providing the intermediate power to the second-stage power converter 104.

[0047] In addition, if Figure 1 As shown in , a control signal C4 may be provided to enable and / or disable the first stage power circuit 110. The control signal C4 may be a logic signal that controls an internal controllable network (not shown) within the first stage power circuit 110. The internal controllable network may provide an internal network signal (also not shown) that causes the first stage power circuit 110 to provide substantially zero output power. For example, the first stage power circuit 110 may operate with a high output impedance and / or in a holding condition in response to the control signal C4. During the holding period, the second stage power converter 102 may receive intermediate power from the holding capacitor 103.

[0048] although Figure 1 The multi-level power conversion system 100 shows an embodiment with a first-level power converter 102 and a second-level power converter 104 using four control signals C1-C4 from a plurality of control signals C1, C2, C3, ..., CN, but other configurations are possible. For example, the multi-level power conversion system 100 can have more than two power converter stages, and more or fewer control signals can be used to adjust the intermediate power.

[0049] Figure 2A A first power converter stage 102 having controllable networks 111, 112, 113, and 212 according to an embodiment is illustrated. The first power converter stage 102 includes a first-stage power circuit 110, which includes a boost PFC controller 208, a boost switch 206, an inductor 202, a bypass diode 203, and a boost diode 204. The inductor 202, the boost switch 206, and the boost diode 204 are electrically connected between the input and output of the first-stage power circuit 110. The PFC controller 208 can provide a gate signal from the GATE output to control the boost switch 206 so that the intermediate voltage V2 is greater than the rectified AC input voltage V1 through power factor correction (PFC). The bypass diode 203 is electrically connected between the input and output of the first-stage power circuit 110 and can be used as a boost surge bypass diode during startup.

[0050] Also like Figure 2AAs shown in , the controllable network 111 can be used to control and / or change the intermediate power (i.e., the intermediate voltage V2 and / or the intermediate current I2) delivered by the first power converter stage 102. The controllable network 111 is electrically connected to receive and / or sample the intermediate voltage V2 at the output of the first stage power circuit 110, at which the controllable network can provide a network signal S1 to the PFC controller 208 at the feedback FDB input. In this way, the controllable network 111 can be used as part of a voltage feedback loop to regulate the intermediate voltage V2. The network signal S1 can be a feedback ratio K FB (ie, feedback scaling / proportional factor) a feedback signal (eg, feedback voltage) related to the intermediate voltage V2; and the control signal C1 can be used to control and / or change the feedback ratio K FB , and thus, changes the intermediate voltage V2. Additionally, in some embodiments, the network signal S1 may be a voltage applied to the input of an error amplifier within a voltage feedback loop.

[0051] Similarly, controllable network 112 and controllable network 212 can be used to control and / or vary the intermediate power. Controllable network 112 is electrically connected to receive and / or sample the rectified AC input voltage V1 and to provide a network signal S2 to PFC controller 208 at a voltage sense VSEN input. Network signal S2 (e.g., AC voltage) can be used by PFC controller 208 to control ratio K V (ie, AC feedback scaling / proportional factor for power factor) proportionally adjusts the power factor of the intermediate power; the control signal C2 can be used to control and / or change the control ratio K V , thereby adjusting the intermediate power (i.e., adjusting the power factor correction). The controllable network 212 is electrically coupled to sample the input current at the sensing node 213 and to provide a network signal S5 to the PFC controller 208 at the current sensing ISEN input. The network signal S5 can also be used by the PFC controller 208 to control the ratio K I Proportionally adjust the power factor of the intermediate power; the control signal C5 can be used to control and / or change the control ratio K I , thereby also adjusting the intermediate power (ie, adjusting the power factor correction).

[0052] The controllable network 113 can also be used to control the AC input current I ACThe intermediate power within the first-stage power converter 102 is controlled by the delivery of the controllable network 113. The controllable network 113 includes a switch 224, a relay 227, and a surge limiting resistor 222. The relay coil 225 is coupled to the bypass potential BP via the switch 224. In response to the control signal C3, the relay coil can be energized (de-energized) to provide a network signal S3 to close (or open) the relay switch 223. The network signal S3 can be a magnetic coupling signal that opens and / or closes the relay switch 223 in response to the control signal C3. When the relay switch 223 is closed, the surge limiting resistor 222 can be bypassed to reduce the impedance between the AC rectifier 108 and the input terminal 103. Reducing the impedance can affect the control of the intermediate power by reducing the loss (i.e., the power loss in the surge limiting resistor 222).

[0053] In one embodiment, when control signal C3 controls switch 224 to close, power may be consumed when network signal S3 is activated; and this in turn may have a measurable impact on system efficiency at light loads. Conversely, during light loads (e.g., light load conditions), the AC input current I AC The input current can be small (for example, can be substantially equal to zero). AC may also flow through the surge limiting resistor 222. Therefore, the losses associated with the surge limiting resistor 222 may also be reduced during light load conditions.

[0054] Additionally, the power loss associated with activation of network signal S3 may be greater than the power loss associated with energy dissipated in surge limiting resistor 222. Thus, deactivating network signal S3 may advantageously enhance performance during light load conditions.

[0055] Additionally, as discussed above, a control signal C4 may be provided to enable and / or disable the first stage power circuit 110. Figure 2A As shown in , the control signal C4 can be provided to the enable EN input of the PFC controller 208. The PFC controller 208 may include an internal network (not shown) that can provide an internal network signal (also not shown) that causes the first stage power circuit 110 to provide substantially zero output power. For example, the control signal C4 can be applied to disable power flow by blocking the gate signal from the GATE output of the PFC controller 208.

[0056] although Figure 2AAn embodiment is shown in which the first power converter stage 102 includes a first stage power circuit 110 using a boost PFC controller 208, but other configurations and / or topologies are possible. For example, instead of using a boost PFC controller 208, the first stage power circuit 110 may use a buck PFC controller; or in some configurations, the first stage power circuit 110 may use a boost converter without PFC.

[0057] Figure 2B A first power converter stage 102 having controllable networks 111 - 113 according to another embodiment is illustrated. Figure 2B The PFC controller 259 does not include an enable EN input and a current sense ISEN input, Figure 2B An implementation similar to Figure 2A Therefore, Figure 2B The first stage power converter 102 also does not include the controllable network 212 and does not receive the control signals C4 - C5 .

[0058] Figure 2B Also shown are circuit components of controllable network 111 and controllable network 112. Controllable network 111 includes resistors 261-263, N-channel FET 260, and filter capacitor 209. N-channel FET 260 receives control signal C1 at its gate and can operate as a switch to control the value of network signal S1 in response to control signal C1. In addition, resistors 263 and 261 are electrically connected between the output of the first stage power circuit 110 and the DC ground GND to create a resistor divider and to provide a network signal S1 proportional to the intermediate voltage V2. Capacitor 209 can be used to filter noise within the network signal S1.

[0059] In addition, if Figure 2B As shown in FIG. 1 , N-channel FET 260 and resistor 262 are electrically connected across resistor 261 such that when N-channel FET 260 is closed (i.e., when N-channel FET 260 has a high gate signal), then resistors 261 and 262 are connected in parallel. Alternatively, when N-channel FET 260 is open (i.e., when N-channel FET 260 has a low gate signal), then resistor 262 is not connected in parallel with resistor 261. In this way, control signal C1 can be used to change the resistor divider ratio (e.g., a feedback ratio K related to the values ​​of resistors 261-263) by applying a gate drive signal to N-channel FET 260. FB ).

[0060] The controllable network 112 includes resistors 256-258, an N-channel FET 255, and a filter capacitor 207. The N-channel FET 255 receives a control signal C2 at its gate and can operate as a switch to control the value of the network signal S2 in response to the control signal C2. In addition, resistors 258 and 257 are electrically connected between the output of the first stage power circuit 110 and the DC ground GND to create a resistor divider and to provide a network signal S2 proportional to the rectified AC input voltage V1. Capacitor 207 can be used to filter noise within the network signal S2.

[0061] In addition, if Figure 2B As shown in FIG. 2 , N-channel FET 255 and resistor 256 are electrically connected across resistor 257 such that when N-channel FET 255 is closed (i.e., when N-channel FET 255 has a high gate signal), then resistors 256 and 257 are connected in parallel. Alternatively, when N-channel FET 255 is open (i.e., when N-channel FET 255 has a low gate signal), then resistor 256 is not connected in parallel with resistor 257. In this way, control signal C2 can be used to change the resistor divider ratio (e.g., a control ratio K related to the values ​​of resistors 256-258) by controlling the gate of N-channel FET 255. V ).

[0062] Figure 3A The second power converter stage 104 according to an embodiment is illustrated. The second power converter stage 104 is a resonant converter topology that isolates the DC ground GND from the isolation ground RTN. The second power converter stage 104 includes a primary circuit 306, a resonant transformer 308, a secondary circuit 309 and a controller 318.

[0063] The primary circuit 306 includes an N-channel power FET 326, an N-channel power FET 328, and a primary driver block 304. The primary driver block 304 receives a switch drive control signal S from the controller 318. DR The gate drive signals GH and GL are provided to the N-channel power FETs 326 and 328, respectively. DR , the primary drive block 304 switches the N-channel power FETs 326 and 328; and in this way, the switched primary circuit 306 switches the signal V X Provided to the input of resonant transformer 308.

[0064] The resonant transformer 308 includes a resonant inductor 322, a magnetizing inductor 324, a resonant capacitor 326, a primary winding 327, a secondary winding 328, and a secondary winding 329. The resonant inductor 322, the magnetizing inductor 324, and the resonant capacitor 326 are connected in series to form a series inductor-inductor capacitor (LLC) network. Therefore, the resonant converter topology can be referred to as an LLC converter. Power is transferred from the primary winding 327 to the secondary windings 328 and 329, where the secondary circuit 309 can be used to provide output power (i.e., output voltage V OUT and output current I OUT ).

[0065] The secondary circuit 309 includes an output capacitor 314, an N-channel FET 310, an N-channel FET 312, and a resistor divider 316. The resistor divider 316 can provide a voltage proportional to the output power (eg, the output voltage V OUT ) is proportional to the feedback signal FB. N-channel FETs 310 and 312 receive gate signals G1 and G2, respectively, and can operate as synchronous rectifiers to improve power transfer. Output capacitor 314 can provide filtering to reduce ripple and / or improve stability.

[0066] like Figure 3A As shown in FIG. 1 , the controller 318 may be an LLC controller configured to provide gate signals G1 , G2 and provide a switch drive control signal S based at least in part on a feedback signal FB. DR In addition, as illustrated, the controller 318 may include a power estimation circuit 320. The power estimation circuit 320 may be used to estimate the output power (ie, the output voltage V OUT and output current I OUT ) and provide control signals C1-C3 in response to load conditions. For example, the power estimation circuit 320 can estimate the output current I OUT Alternatively, the power estimation circuit 320 may estimate that the output power is less than the power threshold. In response to determining that the output power and / or the output current I OUT less than a threshold, the power estimation circuit 320 may change the logic level of one or more of the control signals C1-C3. In some embodiments, the power estimation circuit 320 may provide one or more of the control signals C1-C3 as analog control signals that may vary in relation to the output power.

[0067] In addition, despite Figure 3AAn embodiment of the second power converter stage 104 using an LLC power converter topology is shown, but other configurations and / or topologies are possible. For example, the second power converter stage 104 may use topologies including boost, buck, buck-boost, flyback, etc. In addition, although Figure 3A The power estimation circuit 320 is shown as providing three control signals C1-C3, but other configurations that provide more or less than three control signals C1-C3 are also possible. As can be understood by a person of ordinary skill in the art, the power estimation circuit 320 can use one or more signals (e.g., winding sensing signals from the resonant transformer 308); and although the input signal (e.g., winding sensing signals from the resonant transformer 308) is not illustrated, it can be understood that the power estimation circuit 320 can use one or more signals to estimate power, as described in the applicant's U.S. patent application Ser. No. 16 / 219,529, the entire contents of which are incorporated herein by reference for all purposes.

[0068] Figure 3B A second power converter stage 104 according to another embodiment is illustrated. The second power converter stage 104 uses a controller 330 that is similar to the controller 318 except that the power estimation circuit 320 includes a burst mode detection circuit 331. The burst mode detection circuit 331 can be used to provide a burst mode signal BM. The burst mode signal BM can be a logic signal that changes state (i.e., a high or low logic level) in response to detecting a burst mode (e.g., light load) condition. For example, when the output power and / or output current I OUT is reduced below the threshold level, then the burst mode detection circuit 331 may provide a logic high (or low) burst mode signal BM. Alternatively, when the output power and / or output current I OUT Above the threshold level, the burst mode detection circuit 331 may provide a logic low (or high) burst mode signal BM.

[0069] In addition, if Figure 3B As shown in FIG. 3 , the power estimation circuit 320 includes resistors 332-334. The resistors 332-334 are connected to the output of the burst mode detection circuit 331 to receive the burst mode signal BM respectively. The control signals C1-C3 can be obtained in parallel from the resistors 332-334, and the resistors 332-334 can have resistances to provide signal isolation (i.e., impedance) between the signal paths associated with the signals C1-C3.

[0070] Figure 3C A second power converter stage 104 according to another embodiment is illustrated. The second power converter stage 104 is similar to the first power converter stage 104 except that the second power converter stage 104 uses a controller 353 and a primary circuit 350. Figure 3B The controller 353 and the primary circuit 350 are similar to the controller 330 and the primary circuit 306 except for how the burst mode signal BM is generated. Instead of being generated within the controller 353, the burst mode signal BM is provided from the primary circuit 350.

[0071] Primary circuit 350 includes a primary driver block 352 similar to primary driver block 304 having a power estimation circuit 354 similar to power estimation circuit 320. Power estimation circuit 354 also includes a burst mode detection circuit 356 similar to burst mode detection circuit 331 for providing a burst mode signal BM to resistors 332-334.

[0072] although Figure 3C The embodiment of the primary driver block 352 is illustrated as including a power estimation circuit 354; however, other configurations are possible. For example, Figure 3D The second power converter stage 104 is illustrated according to another embodiment, wherein the primary driver block 352 includes a burst mode detection circuit 356 for providing a burst mode signal BM to the resistors 332-334. Figure 3D As illustrated in , the controller 353 may include a primary estimation circuit 354. As discussed above and herein, aspects of the primary estimation circuit 354 may also be found in the material presented in applicant's US patent application Ser. No. 16 / 219,529.

[0073] Figure 4A A circuit implementation of a burst mode detection circuit 331 for detecting a burst mode according to a first embodiment is illustrated. The burst mode detection circuit 331 includes an error amplifier 402, a compensation network 403, and a comparator 404, and may be a circuit implementation of the burst mode detection circuit 331 as described above with respect to the power estimation circuit 320. The error amplifier 402 receives a feedback signal FB at a non-inverting input and compares it with a reference REF1 at an inverting input. The reference REF1 and the feedback signal FB may be voltages, and for a first order, the error amplifier 402 may function to reduce an error voltage (i.e., a difference voltage) between the reference REF1 and the feedback signal FB.

[0074] In addition, the compensation network 403 can be used to stabilize and / or compensate the error amplifier output voltage V COMP The error amplifier output voltage V COMP The error amplifier output voltage V COMP Compare with the second reference REF2.

[0075] Comparator 404 receives the error amplifier output voltage V at its non-inverting input. COMP , and compares it with the second reference REF2 at the inverting input; in response, the comparator 404 provides a burst mode signal BM. The second reference REF2 can be selected so that the burst mode signal BM will change state (e.g., from a logic low to a logic high) to indicate a burst mode condition. The burst mode condition can be based on the load condition and / or the output power. For example, the burst mode condition can be set to a fixed output power level indicating a light load (e.g., ten percent of the maximum rated output power).

[0076] When the output power decreases, the output voltage V OUT and the feedback signal FB increases, the error amplifier output voltage V COMP can be increased accordingly. Finally, the output power can be reduced so that the error amplifier output voltage V COMP Increases above the second reference REF2 to drive the burst mode signal BM high.

[0077] Figure 4B The circuit implementation of the burst mode detection circuit 431 for detecting the burst mode according to the second embodiment is illustrated. In addition to the signal being configured so that when the error amplifier output voltage V COMP The burst mode detection circuit 431 is similar to the burst mode detection circuit 331 except that the burst mode signal BM indicates a burst mode (i.e., light load) condition when it decreases below the second reference REF2. In this regard, the error amplifier 402 receives the feedback signal FB at its inverting input for comparison with the reference REF1 at its non-inverting input; and the comparator 404 receives the error amplifier output voltage V at its inverting input. COMP , and compares it with a second reference REF2 at its non-inverting input.

[0078] Although the burst mode detection circuits 331 and 431 illustrate a circuit implementation embodiment using only the error amplifier 402, the compensation network 403, and the comparator 404, other analog and / or digital implementations are possible. For example, as will be appreciated by one of ordinary skill in the art, the circuit implementation may include additional analog and / or digital components with analog, mixed, and / or digital signals (e.g., voltage signals and / or current signals).

[0079] Figure 5A illustrates a switching waveform 500a during continuous conduction mode according to one embodiment; and Figure 5B1 illustrates a switching waveform 500b during a burst mode according to an embodiment. The switching waveforms 500a and 500b show waveforms 502, 504, and 506 corresponding to the relationship between the burst mode signal BM, the gate drive signal GH, and the gate drive signal GL and time, respectively. Figure 3A-3C As described, gate drive signals GH and GL may be applied to N-channel power FETs 326 and 328, respectively, to drive N-channel power FETs 326 and 328 in a half-bridge configuration.

[0080] As illustrated, during the continuous conduction mode, the burst mode signal BM can be a logic low value VL3 (e.g., substantially equal to 0); and the gate drive signals GH and GL are continuously switched to drive the N-channel power FETs 326 and 328 in a half-bridge configuration. For example, the gate drive signal GH switches (i.e., transitions) from its low value VL2 to its high value VH2, while the gate drive signal GL switches from its high value VH1 to its low value VL1. When the gate drive signal GH (GL) reaches its low value VL2 (VL1), then the corresponding N-channel power FET 326 (328) is turned off; similarly, when the gate drive signal GH (GL) reaches its high value VH2 (VH1), then the corresponding N-channel power FET 326 (328) is turned on.

[0081] like Figure 5B As shown in , during the burst mode, the burst mode signal BM can be a logic high value VH3 (eg, substantially equal to a digital logic high voltage). Figure 5B As shown in , during the burst mode, switching can be periodically disabled. For example, between time 512 and 514 and between time 516 and 518, the gate drive signals GH and GL are switching. However, between time 514 and 516, switching is disabled (i.e., disconnected). The periodic inhibition of switching can be a characteristic behavior of waveforms 504 and 506 during the burst mode.

[0082] although Figure 5A and Figure 5B An embodiment is shown in which the burst mode signal BM can be a logic low value VL3 during the continuous conduction mode and a logic high value VH3 during the burst mode; however, other embodiments are possible. As can be understood by those of ordinary skill in the art, inverting logic can be used to perform the same and / or similar logic functions. For example, Figure 5C and Figure 5D An implementation is shown where the burst mode signal BM may be a logic high value VH3 during the continuous conduction mode and a logic low value VL3 during the burst mode.

[0083] Figure 5Cillustrates a switching waveform 500c during continuous conduction mode according to another embodiment; and Figure 5D A switching waveform 500d during burst mode according to another embodiment is illustrated. Switching waveforms 500c and 500d are similar to switching waveforms 500a and 500b, respectively, except that the burst mode signal BM follows a waveform 582 that may be inverted relative to waveform 502. For example, when waveform 582 is a logic high value VHS, then waveform 502 may be a logic low value VL3 - inverted relative to waveform 582.

[0084] Fig. 6A The signal waveform 600a during a load step according to an embodiment is illustrated. The signal waveform 600a shows the signal waveforms corresponding to the burst mode signal BM, the error amplifier output voltage V COMP , output voltage V OUT and output current I OUT The waveforms 502, 602, 606 and 610 of the relationship with time. In addition, the burst mode signal BM, the error amplifier output voltage V COMP , output voltage V OUT and output current I OUT It can correspond to the above Figure 3B and Figure 4A The burst mode signal BM and the error amplifier output voltage V COMP , output voltage V OUT and output current I OUT .

[0085] If the output current I OUT As illustrated by waveform 610, there is a load step at or substantially at time 612 and 614. The load step occurring at time 612 and 614 causes waveform 610 to show a transition between burst mode (i.e., current level I3L) to 100 percent full load (i.e., current level I3H). During a time period less than time 612 and greater than time 614, the output current I OUT is low (ie, substantially equal to the light current I3L); and between time 612 and time 614, the output current I OUT It can be at a maximum heavy load (ie, substantially equal to the maximum 100 percent load current I3H).

[0086] In addition, if Fig. 6A As illustrated in , waveform 600a is the same as Figure 3B and Figure 4AThe burst mode detection circuit 331 changes state and changes in unison at times 612 and 614. For example, during the step from burst mode to maximum heavy load at time 612, the burst mode signal BM changes from high to low (i.e., from VH3 to VL3); and during the step from maximum heavy load to burst mode at time 614, the burst mode signal BM changes from low to high (i.e., from VL3 to VH3).

[0087] At time 612, the error amplifier output voltage V COMP From high to low (ie, from VCMPH to VCMPL); and at time 614, the error amplifier output voltage V COMP From low to high (i.e., from VCMPL to VCMPH). In addition, due to system response and / or compensation, the error amplifier output voltage V COMP The waveform 602 shows some undershoot 603 and overshoot 604 after time 612 and 614, respectively. In addition, the output voltage V OUT is approximately and / or substantially equal to its regulated value V30; and at times 612 and 614, the output voltage V OUT Waveform 606 shows undershoot 607 and overshoot 608 .

[0088] As discussed above, the burst mode signal BM may correspond to the previous Figure 3B and Figure 4A The burst mode signal BM described in the embodiment of the present invention can indicate the output power. Figure 1 The control signals C1-C3, CN can be obtained via burst mode signals in some embodiments and can be used to enhance the efficiency of the multi-level power conversion system 100 while allowing the multi-level converter 100 to dynamically undergo a full load step as illustrated at time 612 (i.e., a full load step from burst mode to maximum load).

[0089] As one of ordinary skill in the art will appreciate, a signal may have a response time, which in turn may be reflected in the behavior of waveforms 502, 602, 606, and 610. For example, Figure 6B Illustrated based on similar Fig. 6A The signal waveform 600b of another embodiment of the embodiment of the embodiment. The signal waveform 600b shows the signal waveforms corresponding to the burst mode signal BM, the error amplifier output voltage V COMP , output voltage V OUT and output current I OUT vs. time waveforms 682, 602, 606, and 610; however, vs. Fig. 6A Depending on the implementation scheme, waveform 682 exhibits delay 623.

[0090] As illustrated, the burst mode signal BM transitions from low to high (i.e., from VL3 to VH3) at a time 624 that is delayed relative to time 614. This may be due in part to an asymmetry in the system response time according to load and / or mode changes (e.g., according to operation in continuous conduction mode and / or operation changes in burst mode). For example, at time 612 when experiencing a full load step, the system (e.g., multi-level power conversion system 100) may be configured to respond at a higher response rate (i.e., with a lower response time) than at time 614.

[0091] Figure 7 Curves 704, 708 compare efficiency versus relative output power according to an embodiment of a multi-level power conversion system. Curve 708 may correspond to using Figure 2B The relationship between the efficiency and relative output power of the multi-stage power conversion system of the first stage power converter 102. The first stage power converter 102 can be configured to step up from the rectified AC input voltage V1 (e.g., 230 volts) to the intermediate voltage V2 (e.g., 380 volts) under nominal load conditions. The control signals C1-C3 can be used so that when the second power converter stage 104 transitions to the burst mode, then the controllable network 111-113 causes the intermediate power to decrease (e.g., causing the intermediate voltage V2 to decrease from 380 volts to 330 volts) while still allowing the output power (i.e., the output voltage V OUT and output current I OUT ) is still regulated by the second power converter stage 104. Curve 704 may correspond to a multi-level power conversion system without control signals C1-C3 and may be used for comparison. The multi-level power conversion system corresponding to curve 704 maintains the intermediate voltage during the burst mode (i.e., maintains V2 equal to 380 volts).

[0092] According to the teachings herein, the multi-level power converter system 100 corresponding to curve 708 may experience the same as the multi-level power converter system corresponding to curve 704. Fig. 6A The full load step shown; and Figure 7 As shown in , the multi-level power converter system 100 corresponding to curve 708 advantageously achieves higher efficiency during the burst mode (ie, during light load conditions) and while the relative output power is less than 1.5%.

[0093] Figure 8A conceptual flow chart 800 for controlling intermediate power delivered to a power converter stage using a controllable network according to an embodiment is illustrated. The order of some or all of the steps in the flow chart 800 should not be considered limiting. Rather, one of ordinary skill in the art having the benefit of this disclosure will appreciate that some of the process blocks may be performed in a variety of orders not shown or even in parallel.

[0094] Step 802 may correspond to converting the AC input power into a DC intermediate power using the first power converter stage 102. The DC intermediate power may correspond to the intermediate power as described above (ie, the intermediate voltage V2 and the intermediate current I2).

[0095] Step 804 may correspond to providing a network signal (e.g., a network signal including at least one of network signals S1-S3). Step 806 may correspond to adjusting the intermediate power in relation to the network signal. Figure 2B As described in the embodiment of the present invention, the intermediate power and / or voltage V2 can be adjusted and / or changed by the network signals S1-S3. Step 808 can correspond to using the second power converter stage 104 to convert the DC intermediate power (i.e., the intermediate voltage V2 and the intermediate current I2) into a DC output power (i.e., the output voltage V OUT and output current I OUT ).

[0096] Step 810 may correspond to estimating the output power using the power estimation circuit 320 and / or the power estimation circuit 354. For example, the burst mode detection circuit 331 and / or the burst mode detection circuit 356 may detect the burst mode and may provide a burst mode signal BM. The burst mode signal BM may be used to generate one or more of the network signals S1-S3, as described above with respect to Figure 3B and Figure 3C Then, step 812 may correspond to adjusting the network signal (eg, one or more of the network signals S1 - S3 ) in response to the control signal (eg, the control signals C1 - C3 ).

[0097] The device using the multi-level power converter system described above may be implemented in various electronic devices. Embodiments of the electronic device may include, but are not limited to, consumer electronic products, parts of consumer electronic products, electronic test equipment, and the like.

[0098] According to the concept of multi-level power conversion system, multi-level power conversion system 100 can have multiple configurations, whereby system parameters, signals, voltages, and operating conditions can at least partially determine its efficiency and performance. In addition, according to the teachings of this document, control signals C1-C3 and CN can be used to enhance the efficiency of multi-input power conversion system 100 by controlling the multiple configurations. For example, as described herein, control signals C1-C3 can be adjusted to obtain higher efficiency while utilizing full load steps (e.g., Figure 7 curve 708).

[0099] Examples of operating conditions that may be adjusted and / or controlled using control signals C1-C3 and CN may include, but are not limited to, input and output voltages. Figure 1 , the efficiency of the multi-stage power conversion system 100 may depend at least in part on the relationship between the AC input voltage V1 and the intermediate voltage V2. In some embodiments (e.g., when the first power converter stage 102 is a boost converter stage), the efficiency of the first power converter stage 102 may improve as the intermediate voltage V2 decreases. This may be attributed to a number of reasons including the following: the efficiency of the first power converter stage 102 (e.g., the boost converter stage) increases as its intermediate voltage V2 approaches (i.e., becomes closer in value to) its AC input voltage V1; in addition, the static losses of the first power converter stage 102 may decrease as the intermediate voltage V2 decreases.

[0100] In other embodiments, the efficiency of the multi-level power conversion system 100 may also depend on the second power converter stage 104. For example, the second power converter stage 104 may be configured to deliver an output power (ie, an output voltage V OUT and output current I OUT ) function runs efficiently.

[0101] As presented herein, one aspect of the teaching is a multi-stage power conversion system including a first power converter stage and a second power converter stage. The multi-stage power conversion system is configured to convert an alternating current (ac) input power and provide a direct current (dc) output power to a load. The first power converter stage includes a controllable network. The first power converter stage is configured to regulate a direct current intermediate power in relation to a network signal. The controllable network is configured to provide the network signal based on a control signal. The second power converter stage is electrically coupled in cascade with the first power converter stage. The second power converter stage includes a power estimation circuit. The second power converter is configured to convert the direct current intermediate power into a direct current output power. The power estimation circuit is configured to provide the control signal in response to a direct current output power condition.

[0102] On the other hand, a method of multi-stage power conversion includes: using a first power converter stage to convert alternating current (AC) input power into direct current (DC) intermediate power; providing a network signal via a controllable network; regulating the DC intermediate power in relation to the network signal; using a second power converter stage to convert the DC intermediate power into DC output power for delivery to a load; generating a control signal based on a load condition; and using the control signal to adjust the network signal.

[0103] Regulating the DC intermediate power in relation to the network signal may further include: when the load condition is a burst mode load condition, using the first stage to regulate the DC intermediate voltage; and when the load condition is a continuous conduction mode load condition, using the first stage to regulate the DC intermediate voltage to a second voltage greater than the first voltage.

[0104] The method of multi-stage power conversion may further include: converting the AC input power into a rectified AC input power, wherein the rectified AC input power includes a rectified AC voltage and a rectified AC current. The controllable network may be a resistor network. The resistor network may include a proportional factor (e.g., a feedback ratio K FB ).

[0105] The above description of the illustrated embodiments of the present disclosure, including the content described in the Abstract, is not intended to be exhaustive or to limit the exact form disclosed. Although specific embodiments and embodiments of the available network for changing the inter-stage power transfer in a multi-stage power conversion system are described herein for illustrative purposes, various equivalent modifications are possible without departing from the broader spirit and scope of the present disclosure. In fact, it should be understood that specific example voltages, currents, frequencies, power range values, times, etc. are provided for the purpose of explanation, and other values ​​may also be adopted in other embodiments and embodiments according to the teachings of this article.

[0106] Although the invention is defined in the claims, it will be appreciated that the invention may alternatively be defined according to the following embodiments:

[0107] Embodiment 1: A multi-stage power conversion system, which is configured to convert alternating current (AC) input power and provide direct current (DC) output power to a load, the multi-stage power conversion system comprising: a first power converter stage, which includes a controllable network, wherein the first power converter stage is configured to convert the AC input power into a DC intermediate power and regulate the DC intermediate power in relation to a network signal, and wherein the controllable network is configured to provide the network signal based on a control signal; and a second power converter stage, which is electrically coupled in cascade with the first power converter stage and includes a power estimation circuit, wherein the second power converter stage is configured to convert the DC intermediate power into the DC output power, and wherein the power estimation circuit is configured to provide the control signal in response to a DC output power condition.

[0108] Embodiment 2: The multi-level power conversion system of Embodiment 1, wherein the second power converter stage comprises a resonant converter.

[0109] Embodiment 3: A multi-stage power conversion system according to any one of the preceding embodiments, wherein the first power converter stage comprises: an alternating current (AC) rectifier configured to receive the AC input power and convert the AC input power into a rectified AC input power, wherein the rectified AC input power comprises a rectified AC voltage and a rectified AC current; and a first-stage power circuit configured to convert the rectified AC input power into the DC intermediate power and regulate the DC intermediate power in relation to the network signal, wherein the DC intermediate power comprises a DC intermediate voltage.

[0110] Embodiment 4: The multi-level power conversion system according to any one of the aforementioned embodiments further includes a holding capacitor configured to hold the DC intermediate voltage.

[0111] Embodiment 5: The multi-stage power conversion system according to any one of the preceding embodiments, wherein the first-stage power circuit comprises a boost power factor correction controller.

[0112] Embodiment 6: A multi-stage power conversion system according to any one of the preceding embodiments, wherein the DC output power condition comprises: a light load condition, whereby the second power converter stage operates in a burst mode; and a nominal load condition, whereby the second power converter stage operates in a continuous conduction mode.

[0113] Embodiment 7: The multi-stage power conversion according to any one of the preceding embodiments, wherein the first power converter stage is configured to regulate the DC intermediate power with a high output impedance under the light load condition, and the second power converter stage is configured to receive the DC intermediate power from the holding capacitor.

[0114] Embodiment 8: A multi-stage power conversion system according to any one of the preceding embodiments, wherein the first power converter stage is configured to adjust the DC intermediate voltage to a first voltage under the light load condition; and wherein the first power converter stage is configured to adjust the DC intermediate voltage to a second voltage under the nominal load condition.

[0115] Embodiment 9: The multi-level power conversion system according to any one of the preceding embodiments, wherein the first voltage is less than the second voltage.

[0116] Embodiment 10: The multi-level power conversion system according to any one of the preceding embodiments, wherein the controllable network comprises a switch configured to receive the control signal.

[0117] Embodiment 11: The multi-level power conversion system according to any one of the preceding embodiments further comprises a surge protection circuit configured to reduce surges of the rectified AC current, wherein the switch is configured to bypass the surge protection circuit under the light load condition.

[0118] Embodiment 12: The multi-level power conversion system according to any of the preceding embodiments, wherein the controllable network comprises a resistor network electrically coupled to the first stage power circuit and configured to provide the network signal.

[0119] Embodiment 13: The multi-level power conversion system according to any of the preceding embodiments, wherein the resistor network is configured to sample a first stage power converter signal and provide the network signal comprising the first stage power converter signal multiplied by a scaling factor.

[0120] Embodiment 14: The multi-level power conversion system according to any one of the preceding embodiments, wherein the switch is configured to adjust the scaling factor in response to the control signal.

[0121] Embodiment 15: The multi-level power conversion system according to any one of the preceding embodiments, wherein the first stage power converter signal comprises the rectified AC voltage.

[0122] Embodiment 16: The multi-level power conversion system according to any one of the preceding embodiments, wherein the first stage power converter signal comprises the rectified AC current.

[0123] Embodiment 17: The multi-level power conversion system according to any one of the preceding embodiments, wherein the first-level power converter signal comprises the DC intermediate voltage.

[0124] Embodiment 18: A method of multi-stage power conversion, comprising: using a first power converter stage to convert alternating current (AC) input power into direct current (DC) intermediate power; providing a network signal via a controllable network; regulating the DC intermediate power in relation to the network signal; using a second power converter stage to convert the DC intermediate power into DC output power for delivery to a load; generating a control signal based on a load condition; and using the control signal to adjust the network signal.

[0125] Embodiment 19: A method according to embodiment 18, wherein regulating the DC intermediate power in relation to the network signal further comprises: when the load condition is a burst mode load condition, using the first power converter stage to regulate the DC intermediate voltage to a first voltage; and when the load condition is a continuous conduction mode load condition, using the first power converter stage to regulate the DC intermediate voltage to a second voltage greater than the first voltage.

[0126] Embodiment 20: The method according to any one of the preceding embodiments further includes: converting the AC input power into rectified AC input power, wherein the rectified AC input power includes a rectified AC voltage and a rectified AC current.

[0127] Embodiment 21: The method according to any one of the preceding embodiments, wherein the controllable network is a resistor network, the resistor network comprising a scaling factor.

[0128] Embodiment 22: The method according to any one of the preceding embodiments, further comprising: sampling a first power converter stage signal; and multiplying the first power converter stage signal by the scaling factor.

[0129] Embodiment 23: The method according to any one of the preceding embodiments, wherein using the control signal to adjust the network signal comprises: using a switch to adjust the scaling factor.

[0130] Embodiment 24: The method according to any one of the preceding embodiments, wherein using the switch to adjust the scaling factor comprises: using the control signal to control the switch.

[0131] Embodiment 25: The method according to any one of the preceding embodiments, wherein the first power converter stage signal comprises the rectified AC current.

[0132] Embodiment 26: The method of any one of the preceding embodiments, wherein the first power converter stage signal comprises the rectified AC voltage.

[0133] Embodiment 27: The method according to any one of the preceding embodiments, wherein the first power converter stage signal comprises the DC intermediate voltage.

[0134] Embodiment 28: A multi-stage power conversion system comprises a plurality of power converter stages, the plurality of power converter stages comprising: a first power converter stage comprising a controllable network, wherein the first power converter stage is configured to provide a DC intermediate power and to regulate the DC intermediate power in relation to a network signal, and wherein the controllable network is configured to provide the network signal; and a second power converter stage electrically coupled to the first power converter stage and comprising a power estimation circuit, wherein the second power converter stage is configured to provide a DC output power, and wherein the power estimation circuit is electrically coupled to the controllable network so as to adjust the network signal based on an output power condition.

[0135] Embodiment 29: The multi-level power conversion system of Embodiment 28, wherein the plurality of power converter stages further comprises a third power converter stage electrically coupled in cascade with the first power converter stage and the second power converter stage.

[0136] Embodiment 30 The multi-level power conversion system according to any of the preceding embodiments, wherein the second power converter stage comprises a resonant converter.

[0137] Embodiment 31: A multi-stage power conversion system according to any one of the preceding embodiments, wherein the first power converter stage comprises: a first-stage power circuit configured to provide the DC intermediate power and regulate the DC intermediate power in relation to the network signal, the DC intermediate power comprising a DC intermediate voltage.

[0138] Embodiment 32: A multi-stage power conversion system according to any one of the preceding embodiments, wherein the output power condition comprises: a light load condition, whereby the second power converter stage operates in a burst mode; and a nominal load condition, whereby the second power converter stage operates in a continuous conduction mode.

[0139] Embodiment 33: The multi-level power conversion system according to any one of the preceding embodiments, wherein the DC output power comprises an output current.

[0140] Embodiment 34: A multi-stage power conversion system according to any one of the preceding embodiments, wherein the first power converter stage regulates the DC intermediate voltage to a first voltage under the light load condition; and the first power converter stage regulates the DC intermediate voltage to a second voltage under the nominal load condition.

[0141] Embodiment 35: The multi-level power conversion system according to any one of the preceding embodiments, wherein the first voltage is less than the second voltage.

[0142] Embodiment 36: The multi-level power conversion system according to any of the preceding embodiments, wherein the second power converter stage is configured to convert the output current from a first current to a second current, the second current having a magnitude greater than the first current.

[0143] Embodiment 37: The multi-level power conversion system according to any one of the preceding embodiments, wherein the controllable network comprises switches configured to receive control signals.

[0144] Embodiment 38: The multi-level power conversion system of any of the preceding embodiments, wherein the controllable network comprises a resistor network electrically coupled to the first stage power circuit and configured to provide the network signal.

[0145] Embodiment 39: The multi-level power conversion system according to any of the preceding embodiments, wherein the resistor network is configured to sample a first stage power converter signal and provide the network signal comprising the first stage power converter signal multiplied by a scaling factor.

[0146] Embodiment 40 The multi-level power conversion system according to any one of the preceding embodiments, wherein the switch is configured to adjust the scaling factor in response to the control signal.

[0147] Embodiment 41: The multi-level power conversion system according to any one of the preceding embodiments, wherein the first-level power converter signal comprises the DC intermediate voltage.

Claims

1. A multi-level power conversion system configured to convert AC input power and provide DC output power to a load, the multi-level power conversion system comprising: a first power converter stage comprising a controllable network, wherein the first power converter stage is configured to convert the AC input power into a DC intermediate power and to condition the DC intermediate power in dependence on a network signal, and wherein the controllable network of the first power converter stage is configured to provide the network signal based on a control signal; as well as a second power converter stage electrically coupled in cascade with the first power converter stage and comprising a power estimation circuit, wherein the second power converter stage is configured to convert the DC intermediate power into the DC output power, and wherein the power estimation circuit of the second power converter stage is configured to provide the control signal to the controllable network of the first power converter stage in response to a DC output power condition, The network signal is: Feedback signal; or a voltage signal which is applied to the input of an error amplifier within a voltage feedback loop; or AC voltage sensing signal; or Input AC sensing signal; or an AC input to said first power converter stage; or A signal to enable or disable the first power converter stage. 2 . The multi-level power conversion system of claim 1 , wherein the second power converter stage comprises a resonant converter.

3. The multi-level power conversion system of claim 1 , wherein the first power converter stage comprises: an AC rectifier configured to receive the AC input power and convert the AC input power into a rectified AC input power, the rectified AC input power comprising a rectified AC voltage and a rectified AC current; as well as The first stage power circuit is configured to convert the rectified AC input power into the DC intermediate power and regulate the DC intermediate power in relation to the network signal, wherein the DC intermediate power includes a DC intermediate voltage. 4 . The multi-level power conversion system of claim 3 , further comprising a holding capacitor configured to hold the DC intermediate voltage. 5 . The multi-level power conversion system of claim 4 , wherein the first-stage power circuit comprises a boost power factor correction controller.

6. The multi-level power conversion system according to claim 4, wherein the DC output power condition comprises: a light load condition whereby the second power converter stage operates in a burst mode; as well as Nominal load condition, whereby the second power converter stage operates in continuous conduction mode.

7. The multi-stage power conversion system of claim 6, wherein the first power converter stage is configured to regulate the DC intermediate power with a high output impedance under the light load condition, and the second power converter stage is configured to receive the DC intermediate power from the holding capacitor.

8. The multi-level power conversion system according to claim 6, wherein the first power converter stage is configured to regulate the DC intermediate voltage to a first voltage under the light load condition; and The first power converter stage is configured to regulate the DC intermediate voltage to a second voltage under the nominal load condition. 9 . The multi-level power conversion system of claim 8 , wherein the first voltage is less than the second voltage.

10. The multi-level power conversion system of claim 6, wherein the controllable network comprises a switch configured to receive the control signal.

11. The multi-level power conversion system of claim 10, further comprising a surge protection circuit configured to reduce surges of the rectified AC current, wherein the switch is configured to bypass the surge protection circuit under the light load condition. 12 . The multi-level power conversion system of claim 10 , wherein the controllable network comprises a resistor network electrically coupled to the first stage power circuit and configured to provide the network signal.

13. The multi-level power conversion system of claim 12, wherein the resistor network is configured to sample a first stage power converter signal and provide the network signal comprising the first stage power converter signal multiplied by a scaling factor. 14 . The multi-level power conversion system of claim 13 , wherein the switch is configured to adjust the scaling factor in response to the control signal.

15. The multi-level power conversion system of claim 13, wherein the first stage power converter signal comprises the rectified AC voltage.

16. The multi-level power conversion system of claim 13, wherein the first stage power converter signal comprises the rectified AC current. 17 . The multi-level power conversion system of claim 13 , wherein the first stage power converter signal comprises the DC intermediate voltage.

18. A method of multi-level power conversion, comprising: converting the AC input power into a DC intermediate power using a first power converter stage; providing a network signal via a controllable network of said first power converter stage; regulating the DC intermediate power in relation to the network signal; converting the DC intermediate power into a DC output power for delivery to a load using a second power converter stage; generating, by the second power converter stage, a control signal based on a load condition of the DC output power delivered to the load; and using the control signal to adjust the network signal and thus regulate the DC intermediate power, The network signal is: Feedback signal; or a voltage signal which is applied to the input of an error amplifier within a voltage feedback loop; or AC voltage sensing signal; or Input AC sensing signal; or an AC input to said first power converter stage; or A signal to enable or disable the first power converter stage.

19. The method of claim 18, wherein regulating the DC intermediate power in relation to the network signal further comprises: regulating the DC intermediate voltage to a first voltage using the first power converter stage when the load condition is a burst mode load condition; as well as When the load condition is a continuous conduction mode load condition, the DC intermediate voltage is regulated to a second voltage greater than the first voltage using the first power converter stage.

20. The method according to claim 19, further comprising: The AC input power is converted into a rectified AC input power, wherein the rectified AC input power includes a rectified AC voltage and a rectified AC current.

21. The method of claim 20, wherein the controllable network is a resistor network, the resistor network including a scaling factor.

22. The method according to claim 21, further comprising: sampling a first power converter stage signal; as well as The first power converter stage signal is multiplied by the scaling factor.

23. The method of claim 22, wherein using the control signal to adjust the network signal comprises: Use the switch to adjust the scale factor.

24. The method of claim 23, wherein using the switch to adjust the scaling factor comprises: The switch is controlled using the control signal.

25. The method of claim 22, wherein the first power converter stage signal comprises the rectified alternating current.

26. The method of claim 22, wherein the first power converter stage signal comprises the rectified AC voltage.

27. The method of claim 22, wherein the first power converter stage signal comprises the DC intermediate voltage.

28. A multi-stage power conversion system comprising a plurality of power converter stages, the plurality of power converter stages comprising: a first power converter stage comprising a controllable network, wherein the first power converter stage is configured to provide a DC intermediate power and to regulate the DC intermediate power in dependence on a network signal, and wherein the controllable network of the first power converter stage is configured to provide the network signal; as well as a second power converter stage electrically coupled to the first power converter stage and comprising a power estimation circuit, wherein the second power converter stage is configured to provide a DC output power, and wherein the power estimation circuit is electrically coupled to the controllable network to adjust the network signal provided by the controllable network of the first power converter stage based on an output power condition, The network signal is: Feedback signal; or a voltage signal which is applied to the input of an error amplifier within a voltage feedback loop; or AC voltage sensing signal; or Input AC sensing signal; or an AC input to said first power converter stage; or A signal to enable or disable the first power converter stage.

29. The multi-level power conversion system of claim 28, wherein the plurality of power converter stages further comprises a third power converter stage electrically coupled in cascade with the first and second power converter stages.

30. The multi-level power conversion system of claim 28, wherein the second power converter stage comprises a resonant converter.

31. The multi-level power conversion system of claim 28, wherein the first power converter stage comprises: The first-stage power circuit is configured to provide the DC intermediate power and regulate the DC intermediate power in relation to the network signal, wherein the DC intermediate power includes a DC intermediate voltage.

32. The multi-level power conversion system of claim 31 , wherein the output power condition comprises: a light load condition whereby the second power converter stage operates in a burst mode; as well as Nominal load condition, whereby the second power converter stage operates in continuous conduction mode.

33. The multi-level power conversion system of claim 32, wherein the DC output power comprises an output current.

34. The multi-level power conversion system according to claim 33, wherein the first power converter stage regulates the DC intermediate voltage to a first voltage under the light load condition; and The first power converter stage regulates the DC intermediate voltage to a second voltage under the nominal load condition.

35. The multi-level power conversion system of claim 34, wherein the first voltage is less than the second voltage.

36. The multi-level power conversion system of claim 35, wherein the second power converter stage is configured to transition the output current from a first current to a second current, the second current having a magnitude greater than the first current.

37. The multi-level power conversion system of claim 36, wherein the controllable network comprises switches configured to receive control signals.

38. The multi-level power conversion system of claim 37, wherein the controllable network comprises a resistor network electrically coupled to the first stage power circuit and configured to provide the network signal.

39. The multi-level power conversion system of claim 38, wherein the resistor network is configured to sample a first stage power converter signal and provide the network signal comprising the first stage power converter signal multiplied by a scaling factor.

40. The multi-level power conversion system of claim 39, wherein the switch is configured to adjust the scaling factor in response to the control signal.

41. The multi-level power conversion system of claim 40, wherein the first stage power converter signal comprises the DC intermediate voltage.

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