CN117439388A - Selective damping of ringing in a power converter - Google Patents
Selective damping of ringing in a power converter Download PDFInfo
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- CN117439388A CN117439388A CN202310895788.6A CN202310895788A CN117439388A CN 117439388 A CN117439388 A CN 117439388A CN 202310895788 A CN202310895788 A CN 202310895788A CN 117439388 A CN117439388 A CN 117439388A
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- 238000013016 damping Methods 0.000 title claims abstract description 117
- 238000004804 winding Methods 0.000 claims description 63
- 230000004044 response Effects 0.000 claims description 18
- 239000003990 capacitor Substances 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 10
- 230000001360 synchronised effect Effects 0.000 description 8
- 239000008186 active pharmaceutical agent Substances 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 230000003071 parasitic effect Effects 0.000 description 4
- 238000004891 communication Methods 0.000 description 3
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
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- 239000000463 material Substances 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0038—Circuits or arrangements for suppressing, e.g. by masking incorrect turn-on or turn-off signals, e.g. due to current spikes in current mode control
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
A power converter includes a damping circuit coupled to a dissipating element for dissipating energy corresponding to resonant ringing generated by a magnetic inductance of an energy transfer element and by a switched capacitance when the power converter is in a discontinuous conduction mode.
Description
Cross Reference to Related Applications
This application claims the benefit of U.S. provisional application No. 63/391,099, filed on 7/21, 2022, which is incorporated herein by reference in its entirety.
Background
Technical Field
The present invention relates generally to controlling a power converter, and more particularly to resonant ringing during discontinuous mode. Even more particularly, the invention relates to damping of resonant ringing.
Background
Flyback (flyback) converters are popular circuit topologies for power supplies in low and medium power applications. Flyback converters are used to power a wide range of electronic devices, including cellular telephones, tablet computers, laptop computers, DVD players, and set-top boxes. Flyback converters are switched-mode power supplies with two different modes of operation: discontinuous Conduction Mode (DCM) and Continuous Conduction Mode (CCM). In DCM, an energy transfer element, typically a coupled inductor, reduces its stored energy to zero during each switching cycle. The coupled inductor is an inductor having at least two windings. Typically, in flyback converters, one winding is an input (primary) winding and the other is an output (secondary) winding. In CCM, energy from the current in the winding is stored in the energy transfer element during the whole of each switching cycle.
In DCM, there is dead time (dead time) in which neither the primary winding nor the secondary winding conduct current that contributes to power conversion. During dead time there is typically a ringing of the voltage on the windings of the coupled inductor, sometimes referred to as resonant ringing. Resonant ringing results from the interaction between the magnetizing inductance of the coupled inductor and the parasitic capacitance at the primary switching node. This DCM ringing is typically 400kHz to 1.2MHz and in the middle of the frequency band where such signals are considered undesirable noise and limited by regulatory authorities. The electrical noise generated by the converter may be conducted to another device on the input power line via physical circuitry or parasitic capacitance. Therefore, the size (magnitude) of DCM ringing must be managed.
Drawings
Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.
Fig. 1 illustrates the current through each winding of an energy transfer element in a flyback converter during Discontinuous Conduction Mode (DCM) as in the prior art.
Fig. 2A illustrates an example functional block diagram of a power converter in a flyback configuration using selectively activated circuitry to dampen ringing in accordance with the teachings of the present invention. In an exemplary embodiment, the diode acts as a passive secondary switch. Fig. 2B illustrates a circuit schematic of the power converter shown in fig. 2A in a flyback configuration with an integrated circuit including a power switch with a control circuit.
Fig. 3A illustrates an example functional block diagram of a power converter in a flyback configuration using selectively activated circuitry to dampen ringing in accordance with the teachings of the present invention. In an exemplary embodiment, the synchronous rectifier acts as an active secondary switch. Fig. 3B illustrates a circuit schematic of the power converter shown in fig. 3A in a flyback configuration with an integrated circuit including a power switch with a control circuit.
Fig. 4 shows an example timing diagram illustrating example waveforms of a primary drive signal, a secondary drive signal, a damping enable signal, a switching current, and a switching voltage found in an example power converter. Time interval t 0 To t 4 Discontinuous Conduction Mode (DCM) operation without damping is illustrated. Time interval t 5 To t 10 Discontinuous conduction mode (CCM) operation with damping is illustrated.
FIG. 5 illustrates a flow chart of one example decision process of a damping circuit in accordance with the teachings of the present invention.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments of the present invention. Moreover, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that the specific details need not be employed to practice the present invention. In other instances, well-known materials or methods have not been described in detail in order to avoid obscuring the present invention.
Reference throughout this specification to "one embodiment," "one example," "an example," or "one example" means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "an example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or subcombination in one or more embodiments or examples. The specific features, structures, or characteristics may be included in an integrated circuit, electronic circuit, combinational logic circuit, or other suitable components that provide the described functionality. In addition, it is to be understood that the drawings provided herewith are for explanation purposes to persons ordinarily skilled in the art and that the drawings are not necessarily drawn to scale.
For illustrative purposes, it should be noted that the following description discusses that for the purpose of providing energy, a power converter may be used to provide output voltage and current to a battery powered product. However, it should be appreciated that the present invention may be generally applied to any power converter.
In the embodiments described herein, the teachings are directed to reducing conducted EMI by: after resonant ringing has been detected, for example after the current in the secondary winding has been reduced to zero and the secondary switch has been turned off, the energy in the resonant circuit of the switched-mode power supply is reduced. The resonant circuit being formed by coupling inductorsThe inductance and the effective capacitance at the ends of its windings form. The dominant capacitance is typically associated with a node connected to the primary switch. The primary switch capacitor C PS 120 may include a natural capacitance internal to the coupled inductor 106, as well as a natural internal capacitance of the power switch 116. Capacitor C PS 120 may also represent the following discrete capacitors: the discrete capacitors are deliberately placed in various parts of the circuit to filter noise and slow down switching voltage transitions.
Fig. 1 illustrates the current through each winding of an energy transfer element in a flyback converter during Discontinuous Conduction Mode (DCM) of the prior art.
At t from 0 To t 1 On the primary side of the converter, the primary switch is conductive and will have a constant slope of the drain current I D From the input voltage source through the primary winding to ground. Drain current I D Ramp up until the desired current level is reached, at which point the primary controller turns off the primary switch. When the drain current I D When added, energy is stored in the coupled inductor. During this interval, on the secondary side of the converter, the voltage appearing on the secondary winding places the secondary switch in a non-conducting state.
At time interval t 1 To t 2 During this time, the primary switch is turned off and the energy stored in the coupled inductor is delivered by the current in the secondary winding, placing the secondary switch in a conductive state. The secondary current decays linearly. In the case of DCM, this operation time interval is long enough to attenuate the secondary current to zero.
In DCM, there is an "idle period" or dead time, where both the primary current and the secondary current are zero, as no more energy is required for the output. After this idle period, the switch is turned on again to trigger a new cycle of power conversion. During this idle period, resonant ringing occurs due to the interaction between the magnetizing inductance of the coupled inductor and the energy stored on the parasitic capacitance at the primary switching node.
The power converter in DCM may have a long enough dead timeThe resonant ringing is completely attenuated, e.g., VDS will be comparable to Vin. Resonant ringing during dead time may be in the conducted EMI band, e.g., 400kHz to 1.2MHz, with the allowable size being limited. High frequency ringing adding drain to source voltage source V DS Such as the voltage on the primary switch).
At time interval t 0 To t 1 During which the primary switch conducts and the voltage V across the primary switch DS Is substantially zero. At time interval t 1 To t 2 During this time, when the diode or (or synchronous rectifier) at the secondary side conducts, the voltage on the primary winding is approximately the input voltage (V IN ) Adding the output voltage Vo reflected to the primary winding:
V P ＝nV S
v (V) S ≈V O n is the primary number of turns divided by the secondary number of turns. However, as shown above, there is ringing on the drain voltage of the primary switch before it stabilizes below:
V IN +nV O
after the secondary switch turns off, parasitic capacitance coupling the inductance of the inductor with the drain causes high frequency oscillations at the primary and secondary windings. In the present teachings, damping the resonant ringing just after turning off the secondary switch dissipates the energy in the ringing.
Fig. 2A illustrates an example functional block diagram of a power converter in a flyback configuration using a damping switch and a damping drive circuit to reduce the magnitude and duration of a ringing voltage in accordance with the teachings of the present invention. Fig. 2B illustrates a circuit schematic of the power converter shown in fig. 2A in a flyback configuration with an integrated circuit including a power switch with a control circuit. In the exemplary embodiment, power converter 100 in a flyback configuration uses a diode as a secondary switch.
The power converter 100 may be used to provide energy to an electronic device (e.g., a battery-powered product). Effective primary switched capacitor C illustrated in dashed lines PS 120 denotes a coupling to the power switchAll capacitances on switch 116. Primary switch capacitor C PS 120 may include natural capacitance internal to the energy transfer element, such as coupled inductor 106, as well as natural internal capacitance of power switch 116. Primary switch capacitor C PS 120 may also represent the following discrete capacitors: the discrete capacitors are deliberately placed in various parts of the circuit to filter noise and slow down switching voltage transitions.
The power converter 100 also includes a primary controller 134 and a secondary controller 132. The primary controller 134 controls the switching of the primary switch 116, while the secondary controller 132 controls the switching of the damping switch 138 and the dissipation element 150, e.g., a resistor. The primary controller 134 and the secondary controller 132 may communicate via a galvanically isolated (galvanically isolated) communication link 133.
Although represented schematically as a switch, the damping switch 138 is a conductive modulating device such as a Metal Oxide Semiconductor Field Effect Transistor (MOSFET). Damping switch 138 is coupled to selectively conduct a damping current between forward voltage node 114 and a lower potential node (e.g., referenced to ground).
The energy transfer element 106 includes a primary winding 106A and a secondary winding 106B. Voltage +v on primary winding P From node 112 to node 111. The voltage +vs on the secondary winding goes from the output voltage node 113 to the forward voltage node 114.
The primary controller 134 and the secondary controller 132 may be formed as part of an integrated circuit that is fabricated as a hybrid integrated circuit or a monolithic integrated circuit, as shown as controller 130. In one embodiment, the primary switch 116 may also be integrated with the controller 130 in a single integrated circuit package. In another embodiment, the damper switch 138 may be integrated with the controller 130 in a single integrated circuit package. It should be appreciated that both the primary controller and the secondary controller need not be included in a single controller package, and may be implemented in separate controller packages. Further, the primary controller 134 and the secondary controller 132 may be formed as separate integrated circuits.
The secondary controller 132 includes a selectively activated damping circuit 139 and an output adjustment control 146. The output conditioning control 146 is used to manage the function of the flyback converter.
The selected active damping circuit 139 includes a damping drive circuit 140, a forward voltage detector circuit 144, and a timing circuit 148. The forward voltage detector circuit 144 receives the winding sense WS and identifies the initial resonant ringing on the secondary side and in response enables the damping drive circuit 140. In one embodiment, the enable signal EN is a digital signal, wherein a rising edge in the enable signal EN corresponds to enabling the damping switch 138 to turn on.
When enabled, the damping drive circuit 140 and damping switch 138 generate a damping current I DAMP The damping current I DAMP Is used to dissipate energy in the dissipating element 150 just after the secondary switch 122 has been turned off and resonant ringing begins.
The timing circuit 146 determines the duration for which the damping drive circuit 140 is turned on to damp the resonant ringing. These times are a function of: output current I O Value of (V), input voltage V IN The value of, or primary driving signal P DR And a subsequent secondary drive signal S DR The length of time between the second conducting segments of (a). These parameters can be inferred from the winding sense WS. As an embodiment, the voltage on the secondary winding (e.g., FWD pin in fig. 2A) may be used to sense the input voltage V IN . When the input voltage V IN When increased, the duration that the damping drive circuit 140 is enabled may also be increased, and vice versa.
Fig. 3A illustrates an embodiment of a power converter in a flyback configuration using a damping switch and a damping drive circuit to damp ringing of a resonant circuit in accordance with the teachings of the present invention. Fig. 3B illustrates a circuit schematic of the power converter shown in fig. 3A in a flyback configuration with an integrated circuit including a power switch with a control circuit.
In the illustrative embodiment, the power converter 100 in a flyback configuration uses a Synchronous Rectifier (SR) 122 as a secondary switch for output rectification.
The power converter 100 also includes a primary controller 134 and a secondary controller 132. The primary controller 134 controls the switching of the primary switch 116, while the secondary controller 132 controls the switching of the secondary switch 122 and the damping switch 138 and the dissipation element 150, e.g., a resistor. The primary controller 134 and the secondary controller 132 may communicate via a galvanically isolated communication link 133. The secondary switch 122 may be illustrated as a synchronous rectifier 122. The primary controller 134 and the secondary controller 132 may communicate via a galvanically isolated communication link 133. The primary controller 134 and the secondary controller 132 may be manufactured as described above.
The secondary controller 132 includes a selectively activated damping circuit 139 and an output adjustment control 146. The output conditioning control 146 is used to manage the function of the flyback converter.
In the exemplary embodiment, the secondary controller includes an SR drive circuit 152 that controls the secondary switch 122. The SR drive circuit 152 may generate the drive signal S in response to the enable signal EN DR . Drive signal S DR The on and off transitions of synchronous rectifier 122 may be controlled. The drive signal SR is a digital waveform having a logic high section and a logic low section of varying lengths. When driving signal S DR When logic high, the secondary switch 122 is turned on or conducting. Illustratively, the secondary switch 122 is controlled to turn on after the primary switch 116 is turned off, such that energy stored in the energy transfer element, e.g., the coupled inductor 106, is transferred to the output of the power converter 100 (e.g., to the output capacitor C) when the primary switch 116 is conductive O 124 and load 126). In this embodiment, the current in the secondary winding 110 is in a direction into the forward voltage node 114 to exit the output voltage node 113.
Fig. 4 shows an example timing diagram 400, the example timing diagram 400 illustrating a primary drive signal P found in an example power converter without damping and with damping DR Secondary drive signal S DR Enable signal, primary switching current I D Forward voltage and primary switching powerPressure V DS Signal behavior of an example waveform of (a). Time interval t 0 To t 4 Discontinuous Conduction Mode (DCM) operation without damping is illustrated. Time interval t 5 To t 10 Discontinuous Conduction Mode (DCM) operation with damping is illustrated.
At time interval t 1 To t 2 During which the primary driving signal P DR The primary switch is placed in a conducting mode. Voltage V across primary switch DS Is negligible. The secondary switch 122 is non-conductive and the forward voltage is V OUT +vp/n, where Vp/n is the voltage on the primary winding divided by the winding turns ratio n on the coupled inductor. The turns ratio is defined as the ratio of the number of primary windings to the number of secondary windings.
At time interval t 2 To t 3 During this time, when the synchronous rectifier at the secondary side is conducting (by the secondary drive signal S DR Indication) of the voltage V on the primary winding P Is the input voltage (V) i ) Adding an output voltage V reflected to the primary side O . The forward voltage is comparable to the voltage drop across the synchronous rectifier.
At time interval t 3 To t 4 During which the primary driving signal P DR And a secondary drive signal S DR None are asserted. The power converter is in discontinuous conduction mode. At drain voltage V DS There is a resonant ringing on. The resonant ringing is transferred to the forward voltage node.
Time interval t 5 To t 10 DCM operation with damping is illustrated.
At time interval t 5 To t 6 During which the primary driving signal P DR The primary switch is placed in a conducting mode. The secondary switch being non-conductive and the voltage V across the primary switch DS Is negligible.
At time interval t 6 To t 7 During this time, when the synchronous rectifier at the secondary side is conducting (by the secondary drive signal S DR Indication) of the voltage V across the primary switch DS Is the input voltage (V) IN ) Adding an output voltage V reflected to the primary OR And is combined withAnd there is ringing on the primary switch. The voltage on the primary winding is the output voltage V reflected to the primary side O 。
At time interval t 7 To t 8 During this time, the resonant circuit starts to ring just after the secondary switch has been turned off.
At time interval t 8 To t 9 During this time, when a condition indicating the start of ringing on the primary switch is detected, the forward voltage detector sends EN to the damping drive circuit. In one embodiment, the condition is when V FWD Greater than V O When (1). The damping driving circuit sends a damping enabling D_EN signal to generate a damping current I DAMP Is provided. The duration of the EN signal asserted is determined by the timing circuit and the forward voltage detector circuit.
At time interval t 9 To t 10 During this time, when the EN signal is deactivated, the capacitance in the resonant circuit on the primary switch is discharged, thereby reducing subsequent ringing, as shown on the forward voltage node.
Fig. 5 is a flowchart 500 showing the function of the damping circuit 139. In step 510, it is determined whether the power converter is in DCM? If so, in step 515, V is determined FWD Whether or not it is greater than V OUT . If so, then in step 520, the damping enable D_EN signal is asserted and the damping switch is conducting. The coupled inductor begins to store energy. In step 525, the damping enable D_EN signal is disabled and the damping switch is placed in a non-conductive state. The capacitance in the resonant circuit on the primary switch is discharged, thereby reducing subsequent resonant ringing.
The above description of illustrated embodiments of the invention, including what is described in the abstract, is not intended to be exhaustive or to be limited to the precise forms disclosed. Although specific embodiments and examples of the invention have been described herein for illustrative purposes, various equivalent modifications are possible without departing from the broader spirit and scope of the invention. Indeed, it is to be understood that the specific example voltages, currents, frequencies, power range values, times, etc. are provided for purposes of explanation and that other values may be employed in other implementations and examples in accordance with the teachings of the present invention.
Although the invention is defined in the claims, it should be understood that the invention may alternatively be defined in accordance with the following examples:
embodiment 1. A power converter includes: an energy transfer element having primary and secondary windings, a forward voltage node, and an output voltage node; a primary switch having a non-conductive state and a switched capacitance, coupled to the primary winding and to a reference ground; a dissipative element coupled to the forward voltage node; and a secondary controller coupled to the secondary winding, comprising: a secondary switch having a non-conductive state, and a damping circuit coupled to the dissipating element to selectively generate a damping current in response to the primary switch and the secondary switch being in the non-conductive state, wherein the dissipating element receives the damping current and, in response, dissipates energy corresponding to resonant ringing generated by a magnetic inductance of the energy transfer element and by the switched capacitor.
Embodiment 2. The power converter of embodiment 1, the damping circuit further coupled to selectively generate the damping current in response to the primary switch and the secondary switch being in a non-conductive state and the voltage at the forward voltage node being greater than the voltage at the output voltage node.
Embodiment 3. The power converter of embodiment 2, the damping circuit includes: a forward voltage detector circuit coupled to the energy transfer element to generate an enable signal when a voltage at the forward voltage node is greater than a voltage at the output voltage node; a timing circuit; a damping drive circuit coupled to the forward voltage detector circuit and the timing circuit to generate a damping enable signal; and a damping switch coupled to receive the damping enable signal.
Embodiment 4. The power converter of embodiment 1 wherein the damping circuit is coupled to the dissipating element.
Embodiment 5. The power converter of embodiment 1 wherein the damping circuit is coupled between the negative terminal of the secondary winding and a reference ground.
Embodiment 6. The power converter of embodiment 1 wherein the damping circuit is coupled between the negative terminal of the secondary winding and a bypass terminal of the switch mode power supply.
Embodiment 7. A method for damping ringing in an energy transfer element, comprising: detecting a discontinuous conduction mode of a power converter having an energy transfer element; comparing a voltage on a secondary winding of the energy transfer element with an output voltage of the energy transfer element; generating a damping current; and dissipating energy in the ringing.
Embodiment 8. The method of embodiment 7, the step of generating the damping current further comprises: a damping current is generated in response to a voltage on a secondary winding of the coupled inductor being greater than an output voltage of the energy transfer element.
Other embodiments:
although the invention is defined in the appended claims, it should be understood that the invention may also (alternatively) be defined in accordance with the following embodiments:
1. a power converter, comprising:
an energy transfer element having primary and secondary windings, a forward voltage node, and an output voltage node;
a primary switch having a non-conductive state and a switched capacitance, coupled to the primary winding and to a reference ground;
a dissipative element coupled to the forward voltage node; and
a secondary controller coupled to the secondary winding, comprising:
a secondary switch having a non-conductive state, an
A damping circuit coupled to the dissipative element to selectively generate a damping current in response to the primary switch and the secondary switch being in the non-conductive state,
wherein the dissipating element receives the damping current and, in response, dissipates energy corresponding to resonant ringing produced by the magnetic inductance of the energy transfer element and by the switched capacitor.
2. The power converter of embodiment 1, the damping circuit further coupled to selectively generate the damping current in response to the primary switch and the secondary switch being in the non-conductive state and the voltage at the forward voltage node being greater than the voltage at the output voltage node.
3. The power converter of embodiment 2, the damping circuit comprising:
a forward voltage detector circuit coupled to the energy transfer element to generate an enable signal when a voltage at the forward voltage node is greater than a voltage at the output voltage node;
a timing circuit;
a damping drive circuit coupled to the forward voltage detector circuit and the timing circuit to generate a damping enable signal; and
a damping switch coupled to receive the damping enable signal.
4. The power converter of embodiment 1 wherein the damping circuit is coupled to the dissipating element.
5. The power converter of embodiment 1 wherein the damping circuit is coupled between a negative terminal of the secondary winding and a reference ground.
6. The power converter of embodiment 1 wherein the damping circuit is coupled between a negative terminal of the secondary winding and a bypass terminal of a switch mode power supply.
7. A method for damping ringing in an energy transfer element, comprising:
detecting a discontinuous conduction mode of a power converter having an energy transfer element;
comparing a voltage on a secondary winding of the energy transfer element with an output voltage of the energy transfer element;
generating a damping current; and
dissipating energy in the ringing.
8. The method of embodiment 7, the step of generating a damping current further comprising: a damping current is generated in response to a voltage on a secondary winding of the coupled inductor being greater than an output voltage of the energy transfer element.
9. A power converter, comprising:
an energy transfer element having primary and secondary windings, a forward voltage node, and an output voltage node;
a primary switch having a non-conductive state and a switched capacitance, coupled to the primary winding and to a reference ground;
a dissipative element coupled to the forward voltage node; and
a secondary controller coupled to the secondary winding, comprising,
a secondary switch having a non-conductive state, an
A damping circuit coupled to the dissipative element configured to: selectively generating a damping current in response to the primary switch and the secondary switch being in the non-conductive state and the voltage at the forward voltage node being greater than the voltage at the output voltage node,
wherein the dissipating element receives the damping current and, in response, dissipates energy corresponding to resonant ringing produced by the magnetic inductance of the energy transfer element and by the switched capacitor.
10. The power converter of embodiment 9, the damping circuit comprising:
a forward voltage detector circuit coupled to the energy transfer element and configured to generate an enable signal when a voltage at the forward voltage node is greater than a voltage at the output voltage node;
a timing circuit;
a damping drive circuit coupled to the forward voltage detector circuit and the timing circuit to generate a damping enable signal; and
a damping switch coupled to receive the damping enable signal.
11. The power converter of embodiment 9 wherein the damping circuit is coupled to the dissipating element.
12. A method for damping ringing in an energy transfer element, comprising:
detecting a discontinuous conduction mode of a power converter having an energy transfer element;
comparing a voltage on a secondary winding of the energy transfer element with an output voltage of the energy transfer element;
generating a damping current when a voltage on a secondary winding of the coupled inductor is greater than an output voltage of the energy transfer element; and
dissipating energy in the ringing.
Claims (12)
1. A power converter, comprising:
an energy transfer element having primary and secondary windings, a forward voltage node, and an output voltage node;
a primary switch having a non-conductive state and a switched capacitance, coupled to the primary winding and to a reference ground;
a dissipative element coupled to the forward voltage node; and
a secondary controller coupled to the secondary winding, comprising:
a secondary switch having a non-conductive state, an
A damping circuit coupled to the dissipative element to selectively generate a damping current in response to the primary switch and the secondary switch being in the non-conductive state,
wherein the dissipating element receives the damping current and, in response, dissipates energy corresponding to resonant ringing produced by the magnetic inductance of the energy transfer element and by the switched capacitor.
2. The power converter of claim 1, the damping circuit further coupled to selectively generate the damping current in response to the primary switch and the secondary switch being in the non-conductive state and a voltage at the forward voltage node being greater than a voltage at the output voltage node.
3. The power converter of claim 2, the damping circuit comprising:
a forward voltage detector circuit coupled to the energy transfer element to generate an enable signal when a voltage at the forward voltage node is greater than a voltage at the output voltage node;
a timing circuit;
a damping drive circuit coupled to the forward voltage detector circuit and the timing circuit to generate a damping enable signal; and
a damping switch coupled to receive the damping enable signal.
4. The power converter of claim 1 wherein the damping circuit is coupled to the dissipating element.
5. The power converter of claim 1 wherein the damping circuit is coupled between a negative terminal of the secondary winding and a reference ground.
6. The power converter of claim 1 wherein the damping circuit is coupled between a negative terminal of the secondary winding and a bypass terminal of a switch mode power supply.
7. A method for damping ringing in an energy transfer element, comprising:
detecting a discontinuous conduction mode of a power converter having an energy transfer element;
comparing a voltage on a secondary winding of the energy transfer element with an output voltage of the energy transfer element;
generating a damping current; and
dissipating energy in the ringing.
8. The method of claim 7, the step of generating a damping current further comprising: a damping current is generated in response to a voltage on a secondary winding of the coupled inductor being greater than an output voltage of the energy transfer element.
9. A power converter, comprising:
an energy transfer element having primary and secondary windings, a forward voltage node, and an output voltage node;
a primary switch having a non-conductive state and a switched capacitance, coupled to the primary winding and to a reference ground;
a dissipative element coupled to the forward voltage node; and
a secondary controller coupled to the secondary winding, comprising,
a secondary switch having a non-conductive state, an
A damping circuit coupled to the dissipative element configured to: selectively generating a damping current in response to the primary switch and the secondary switch being in the non-conductive state and the voltage at the forward voltage node being greater than the voltage at the output voltage node, wherein the dissipating element receives the damping current and, in response, dissipates energy corresponding to resonant ringing generated by the magnetic inductance of the energy transfer element and by the switched capacitance.
10. The power converter of claim 9, the damping circuit comprising:
a forward voltage detector circuit coupled to the energy transfer element and configured to generate an enable signal when a voltage at the forward voltage node is greater than a voltage at the output voltage node;
a timing circuit;
a damping drive circuit coupled to the forward voltage detector circuit and the timing circuit to generate a damping enable signal; and
a damping switch coupled to receive the damping enable signal.
11. The power converter of claim 9, wherein the damping circuit is coupled to the dissipating element.
12. A method for damping ringing in an energy transfer element, comprising:
detecting a discontinuous conduction mode of a power converter having an energy transfer element;
comparing a voltage on a secondary winding of the energy transfer element with an output voltage of the energy transfer element;
generating a damping current when a voltage on a secondary winding of the coupled inductor is greater than an output voltage of the energy transfer element; and
dissipating energy in the ringing.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US63/391,099 | 2022-07-21 | ||
| US18/142,485 | 2023-05-02 | ||
| US18/142,485 US20240030809A1 (en) | 2022-07-21 | 2023-05-02 | Selective damping of ringing in a power converter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117439388A true CN117439388A (en) | 2024-01-23 |
Family
ID=89545199
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310895788.6A Pending CN117439388A (en) | 2022-07-21 | 2023-07-20 | Selective damping of ringing in a power converter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117439388A (en) |
-
2023
- 2023-07-20 CN CN202310895788.6A patent/CN117439388A/en active Pending
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