TW200807849A - Forward power converters and controllers - Google Patents

Abstract

This invention generally relates to forward power converters, and more particularly to improved systems and methods for operating such converters, and to controllers for implementing these systems and methods. We describe a discontinuous resonant forward power converter including a controller having an output coupled to a controllable switch and which is configured to control the switch such that a voltage waveform on a secondary winding of a transformer of the converter has a first portion during which the switch is on and current flows into an output node of the converter which is coupled to the output rectifier and to a smoothing capacitor, and which has a second substantially resonant portion during which the switch and an output rectifier are both off. Substantially no current flows into the output node during the second portion of said voltage waveform.

Description

200807849 IX. INSTRUCTIONS: t FIELD OF THE INVENTION Field of the Invention The present invention relates generally to forward power converters, and more particularly to resonant 5 discontinuous forward power converters (RDFCs), and to operating such converters Improved systems and methods, and controllers for implementing these systems and methods. [Prior Art 3 Background of the Invention 10 Figure 1 (taken from U.S. Patent No. 4,688,160) shows an exemplary forward power converter comprising one of the primary windings 1 〇 9 of the transformer 110, DC input 101, 102. The main winding 109 is connected in series with a switching device 1〇5, wherein the switching device is a bipolar transistor which is turned on and off, and the magnetic flux in the main winding 109 is increased during an conducting period to drive the primary winding of the transformer. One of the electricity. Rather than a so-called flyback converter, the primary and secondary windings are polarity matched in a forward converter, as indicated by the point on the winding in Figure 1. The output of transformer 110 is rectified by a rectifier 114 and leveled by a leveling capacitor 119 to provide a DC output 121,122. When the switch 105 is turned off, the core of the transformer is "reset" to return the magnetic flux to its initial 20 state. In the example of Fig. 1 (U.S. Patent No. 4,688,160), this is carried out by a resonant action between the magnetic inductance of the transformer 110 and a shunt diode 114 of a capacitor 113, which returns energy to the input voltage source. The circuit of Fig. 1 includes a large output plug 117 between the rectifier 114 and the leveling capacitor 119, and a free-wheeling or "return-type" of the series connection of the plug 117 and the leveling capacitor Π9. Diode 115. This is because when the switch 105 is turned off, since the primary and secondary windings have the same induction, the rectifier 114 immediately becomes non-conductive. The function of the freewheeling diode 115 allows the plug 117 to maintain a continuous output current into the output node "X" by providing a path for the current when the switch 1〇5 is turned off. Figure 1 shows a conventional continuous forward converter. There are a number of prior documents describing such converters, including, for example, U.S. Patent No. 4,415,959, U.S. Patent No. 6,760,236, U.S. Patent No. 6,304,463, U.S. Patent No. 6,252,871, EP 0 074 399, EP 0055064 A, and Deutsche UCC 38 C42 10 Reference Design SLUA 276 . The secondary side diodes of the back end of these prior cases are replaced by synchronous rectifiers in the MOS transistor state. A further background of the prior art can be found in U.S. Patent No. 4,788,634, which describes a resonant forward converter in which a natural self-inductance of a transformer in parallel with a transformer provides a resonant "ring" that allows the switching circuit to self-resonate; Patent No. 15 2005/0270809 (W02004/057745), which describes the use of an auxiliary transformer in a current limiting circuit. The inventors have confirmed that the improved operation of the present invention, such as improved regulation and activation, can be achieved by utilizing switching control in a discontinuous current mode. 20 SUMMARY OF THE INVENTION In accordance with a first aspect of the invention, a discontinuous resonant forward converter for converting an input DC voltage to an output DC voltage is provided, the converter comprising: first and second DC inputs a transformer having a polarity of 6 200807849 with primary and secondary windings; a controllable switch for switching power from the DC input through the primary winding of the transformer, the controllable switch and the primary of the transformer a winding coupled in series between the first and second straight voltage inputs; first and second DC voltage outputs; a rectifier coupled to the secondary winding of the transformer 5, the rectifier and the transformer The secondary winding is coupled in series between the first and second DC voltage turns, and a leveling capacitor 'which has been coupled to receive DC current from the rectified state at a first connection node a first connection node, the first connection node is connected to the brother's DC voltage output, and the leveling capacitor has a second connection to the second DC voltage output And a controller coupled to the controllable switch and configured to control an output of one of the switches such that a voltage waveform on the secondary winding is turned on and current flows into the first connection node Having a first portion and having a second substantial resonant portion during the turn-off of the switch; and wherein substantially no current flows into the first connection node during the second portion of the voltage waveform. A connection between the rectifier and the first connection node has an inductive coil, and wherein no current flows into the inductive coil during substantially the second portion of the waveform. However, it is not necessary to use the aforementioned large plug in the continuous forward converter. If it has an inductor, this can have a value less than 1% of the inductance of the transformer, or less than 0.1%. The embodiment of the forward converter is not coupled to one of the secondary winding freewheeling rectifiers. A small number of output inductors can be used to assist in implementing the current limit function (described later) for the converter to remain discontinuous. As described above, a forward converter according to an embodiment of the present invention, 7 200807849 "uses the control of the switch instead of relying on self-vibration to directly control the power switch. The inventor will recognize the forward conversion The embodiment of the device can accommodate the variation of the number of components, the inductance of the specific transformer and the capacitance of the resonant capacitor, the two-frequency shoes. The inventor will recognize that - discontinuous resonance is smooth (four) ^ 'anti-intuitive, can be applied - Real (iv) constant frequency oscillator and = phase_component value „ robustness, which in turn facilitates the use of components with a second degree and thus reduces costs. (d) Yes, roughly speaking, : Man: The forward converter of the electric star waveform on the winding will be a period of time, the middle voltage waveform is formed into a period of -) and the voltage:: 'It occupies these three Two of the three periods of the period. a shellfish resonance portion that occupies a (previous) conduction period by which the control switch is driven, the opening is at least nearly twice the string resonance and the waveform is approximately zero volts I to more than half the positive period of 15 cycles and In the embodiment, the use, = (the waveform is clamped on the main end, after the use is said, in fact, the diode is lower than the pole of the transistor switch surface, ρθ w from zero volts It is clamped because the right #-pole is in the switch). # U is in the inner, is the main voltage waveform is turned on again, the voltage is essentially zero volts, then the dandan V-pass main end switch ~ gang special disturbance (Li) and achieve good benefits. The ancient machine 'can reduce the electric interference at this time. The electric waveform is kept at the real (four) volts, a relatively long period, the period is selected to allow some variation in the half cycle 且' and (4) the vibrator frequency can be voltage The duration of the second pass is turned on at substantially zero volts. When the ink changer changes. Therefore, preferably, such a solid can be significantly improved by 2.0 - duty cycle (the conduction period has less than 15: in the end period X is alternatively, the percentage is small 8 200807849 10 70% of the total period - the conduction period waveform Start the sine duty cycle). Finally, the secondary winding power period is short enough for U & second person 23 rings 'and 21 this is more than the (four) guard cycle interception i" avoid this waveform area, so compared to #地,如如, "¥通通=得_ _ even ratio ^5:2.G (alternatively, the total period of the working period of the period is more than 5% of the total time · additionally or alternatively, pulse width modulation (PWM) and pulse frequency modulation (p loss) It—or both—can be used to maintain the regenerative resonance. This facilitates the regulation of the forward converter's input ilj', especially under varying negative contacts. However, it is preferred that the switching controllers are configured to use a pair of controls. The signal is used to control the switch 'one--the control signal is used to make „ conduction, and the second control signal is used to stop the escrow. This helps to implement different control strategies, optionally in PWM, and/or In the context of the ship, in particular, this contributes to the zero-volt switching (ZVS) and the overcurrent protection (OCP) in the context of a discontinuous resonant forward converter. 15 Thus in some preferred embodiments, A first control signal controls the switch to be turned on and a second control signal controls the switch to be turned off. In an embodiment, the _th control signal can be Responding to a substantially zero volt condition detected on the primary winding voltage. This can be used to turn the power switch on immediately or after a delay. Alternatively, one of the auxiliary windings from one of the transformers can be used. Generally, the sensed voltage can be compared to a reference level and is not necessarily zero volts. In yet another type of power switch, it can be turned on in response to a current flowing through one of the main windings and the switch, such as by measuring one. A voltage drop across the current sense resistor is sensed. This can be used, for example, to delay the conduction of the power switch. The second control signal to turn off the power switch can also respond to one or more of the different causes of 200807849 For example, in a simple embodiment, the second control signal can control the switch to be turned off after the time delay of the power switch is turned on from the first control signal. Optionally, the time delay can be varied, and the pulse width modulation can be implemented in this manner. The pulse width may be responsive to, for example, a voltage on the primary or auxiliary winding of the transformer, and/or in response to a sense on the secondary side of the forward converter. Voltage. It should be understood that, in general, the voltage on the primary (or secondary) winding of the transformer can be sensed directly or indirectly. Typically, the second control signal can be responsive to any primary or secondary voltage or current. In some specific preferred embodiments, the second control signal implements an overcurrent protection (OCP) function to substantially instantaneously switch the power switch off when an overcurrent condition is detected, such as via a sensor. The voltage sensed (eg, a current sense resistor). This can be used to implement an ocp during a week and to help respond quickly when a switch current is detected that is greater than a critical value. In some preferred embodiments, the controller implements a current The limit mode, which includes adding fresh operation, is therefore used to increase the i-rate of the drive signal when the current is limited. This helps to avoid - uncontrollable processing (called post-production), which causes a constant drop in output voltage for a certain load. In the implementation of the financial, the current limit - the critical current dynamic signal change frequency or pulsation f p A1., the fly-off version of the wave is adjusted, and in a specific critical electricity

The lower can be increased as the drive pulse width decreases or the drive frequency increases. As described in the previous L, the output of the forward converter can be packaged. Small «, and capacity _ in - discontinuous resonance mode, and including this; over load output current, _ is __ section) 疋 疋 由 by facilitating the adjustment of the output current, as described above. In an embodiment, this Rayaway inductance can be leaked or parasitic in the circuit. 20 200807849 In an embodiment, the transformer provides a sense of inductance to the converter, particularly the transformer (10) inductance. The device can be configured to increase a leakage inductance for a desired output inductance value. '2 to the power conversion transfer often occurs - the type of _ is then to ensure the guilty start. This is because the forward converter output forms the same short circuit at startup, which can potentially damage the power supply switch where a current limit configuration is located or trigger a current limit because (4) the output voltage reaches its proper value. The forward converter embodiment we describe employs a configuration to facilitate the management of a forward converter startup in a controlled manner to turn the power switch on and off, and in particular, to use one of the drive signals. Increase the power of the switch to start. This causes the converter to leave its operating resonant mode when it starts and causes more power to be transferred to the output while still protecting the power switch. The startup condition can be detected directly at the primary end of the forward converter or indirectly by using one of the forward converters. In some particularly preferred embodiments, the aforementioned controller is implemented as a single integrated circuit. This 1C can implement one or more control strategies as previously described. However, in some preferred embodiments of 1C, the power switch is not on the wafer for compatibility reasons. Therefore, in another aspect of the invention, a controller for controlling a forward converter is provided for converting an input DC voltage into an output DC voltage, the converter comprising: first and a DC input; a transformer having a polarity-matched primary and secondary winding; a controllable switch for switching power from the DC input through the primary winding of the transformer, the controllable switch and the primary winding of the transformer Between the first and second DC voltage inputs; the first and second DC voltage outputs; a rectifier coupled to the secondary winding of the transformer, the rectifier and the transformer The winding is coupled in series between the first and second DC voltage outputs; and has a leveling capacitor coupled to a first connection node for receiving a first connection of one of the DCs from the rectifier, The first connection node is coupled to the first DC voltage output, the leveling capacitor having a second connection coupled to the second DC voltage output; The controller has a control coupled to the controllable switch and is configured to control an output of the switch such that a voltage waveform on the secondary winding has a voltage during the switch 10 being turned on and current flowing into the first connection node a first portion, and having a second substantial resonance portion during the off period of the switch; and wherein substantially no current flows into the first connection node during the second portion of the voltage waveform; thereby the forward conversion The device can be controlled by the controller to operate in a discontinuous forward voltage conversion mode. Preferably, the controller is implemented as described above on a single integrated circuit. A still further aspect of the present invention provides a method of controlling a forward converter operating in a discontinuous resonant mode by controlling a controllable (power) switch such that a voltage waveform on the secondary winding has a first In part, the switch is turned on and current flows into the first connection node and a second 20 substantial resonance portion, during which the switch is turned off and substantially no current flows into the first connection node during the second portion of the voltage waveform. According to another aspect of the present invention, a controller for a resonant discontinuous forward converter (RDFC) is provided, the forward converter including a transformer having polarity-matched first and second windings and for switching DC to 12 200807849 A switch of the first winding of the transformer, the converter further having a DC output coupled to the second winding of the 忒, the voltage exchanger, wherein the control piano has two modes ··- a mode that is used to switch the DC power to a frequency that is substantially synchronized with the resonant frequency of one of the RDFCs during operation of the switch, such that the DC output is powered, and a first The reduced power mode of operation during which the drive of the switch is controlled to increase the proportion of time during which the switch is turned off. In some preferred embodiments, the switch drive includes a pulse and the pulse width (continuous) is reduced, in the second reduced power mode of operation. One or more of the resonant frequency cycles of the switch are skipped in the reduced power mode of operation. In the latter case, when the switch is subsequently turned on, to further increase the efficiency of the RDFC turn-on, the timing is substantially synchronized with a turn-on point, more specifically a valley of one of the resonant waveforms of the RDFC. In some preferred embodiments, the controller is configured to automatically sense a low load condition and to select a second reduced power mode of operation in response thereto. For example, the controller can sense a reduced load condition by sensing one of the power supplies to the control state, where the controller is applied as a one-piece circuit to one of the 1C voltage sources. Alternatively or additionally, the controller may select to reduce the power mode by sensing the operating clock of the RDFC, particularly during the power-on 20 off period (cycles above one cycle). Further operations for identifying reduced load conditions include sensing at one of the outputs of the RDFC (e.g., utilizing a current sense resistor at the output of the forward converter) and sensing by one of the auxiliary windings on the transformer. In some particularly preferred embodiments, the controller is configured to control the drive of switch 13 200807849 such that the switch is turned on only when the voltage on the switch is near 〇¥. (In a practical example, the voltage on the switch may in fact never be 〇v, because, for example, because there is a diode drop); this is especially useful. In some preferred embodiments, the second reduced power mode of operation includes a 5 RDFC standby mode. According to another aspect of the present invention, a controller for a plug-in resonant discontinuous forward converter (RDFC) is provided, the forward converter including a transformer having polarity-matched first and second windings, and Switching to a switch of the direct current of the first winding, wherein the converter further has a DC output coupled to the second winding of the transformer, and wherein the DC system to the first winding Deriving from a total power supply and including one component of total chopping, the controller includes: a chopper sensing input for sensing the total chopping, and lightly connecting to the chopping sensing input and having a clock control module for controlling an output of one of the drive signals of the switch, the drive 15 includes a pulse wave having a pass period for driving the switch to be turned on, and a pulse wave for driving the switch to cut off a pulse of a deadline; and wherein the clock control module is configured to responsive to the second total chopping to change one or both of a width and a frequency of the pulse to suppress the DC The chopping in the output One of the ingredients. 20 The chopper sensing input senses household or grid total chopping at most points, including, but not limited to, the DC output of the RDFC, the switch, and an auxiliary winding from the transformed state of rdfC. Preferably, the controller also includes a further sense input for adjusting the DC output of the converter. Preferably, the clock control module output includes first and second output lines for respectively controlling the switch guide 14 200807849 on and off; the controller preferably further includes a switch control module responsive to the output lines for controlling The switch turns on or off an off. A method for suppressing chopping in a plug-in resonant discontinuous forward converter (RDFC) including first and second windings having polarity matching is provided in a related aspect of the invention a transformer, and a switch for switching to a direct current of the first winding of the transformer, the converter further having a DC output coupled to the second winding of the transformer, the method comprising: sensing the RDFC a component of the total chopping wave in a signal; and a pulse width of one of the driving signals of the switch and a frequency of a pulse wave of 10 of which are either " or both to suppress the continuous wave. In another yet another aspect of the invention, a controller for a resonant discontinuous forward converter (RDFC) is provided, the RDFc comprising a transformer and a power switch for switching to the DC power of the transformer, wherein the control The system is configured to limit one of the currents in the switch during startup of the RDFC. In an embodiment, the switch comprises a transistor, particularly a bipolar transistor, and the current limit can comprise operating the transistor in a non-linear region. Additionally or alternatively, the controller can be configured to increase the frequency of one of the control signals to initiate switching to limit current during this time. The frequency can be increased by a factor, for example, 2, 5, 10 or more above a normal operating frequency. Therefore, in the actual implementation, the controller can be configured to control the rainbow DC to make it non-resonant at startup. The start-up solution can include a fixed frequency or a frequency that is determined by the _ 4 Lu number and 疋. In yet another aspect of the invention, 56.  a controller for a resonant discontinuous forward converter (pin c), the rdfc comprising a transformer 15 200807849 and a power switch for switching to the DC power of the transformer, wherein the open relationship Switching to power to one of the windings of the transformer, wherein the controller includes a system for sensing a voltage in the winding of the transformer and controlling the portion of the switch to conduct in response to the sensing. 5 In this embodiment, the transformer includes an input winding and an output winding that are coupled to switch the power to the input winding of the transformer. At one of the nodes on the input winding to which the switch is connected, an imminent voltage rise occurs when the switch is turned off (generally in response to the input and output winding ends of the transformer being inconsistent), and this voltage overshoot can be partially turned on. The switch is controlled and limited by 10, in the effect of sensing and overshooting. Therefore, at another level of the invention, there is provided a method of controlling a resonant discontinuous forward converter (RDFC), the RDFC comprising a transformer and a power switch for switching to the DC power of the transformer, the method comprising sensing the transformer A voltage on the winding and a step of controlling the switch to be turned on 15 in response to the sensing to limit voltage overshoot. In another aspect of the invention, there is provided a current limiting method in a resonant discontinuous forward converter, the forward converter comprising a transformer having one of a polarity matched first and second windings, and for switching to a switch of the direct current of the first winding of the transformer, the converter further having a DC output coupled to one of the second windings of the transformer, the method comprising detecting a current limiting condition; and responsive to the detecting increasing to One of the switches controls a frequency of the signal. In a related aspect of the invention, a controller for a resonant discontinuous forward converter (RDFC), a transformer having a polarity-matched first and second 16 200807849 windings, and a switch for switching to the transformer are provided a switch of the direct current of the first winding, the converter further having a DC output coupled to the second winding of the transformer, the controller comprising: means for detecting a current limiting condition; and responsive to the A means of detecting a frequency that is added to one of the switches to control the 5-signal. The present invention still further provides a controller for a resonant discontinuous forward converter (RDFC) having one or more signals for sensing one or more signals from the resonant discontinuous forward converter a multi-input, the controller further comprising: a system for analyzing the one or more sensed signals, 10 for determining a turn-on and a turn-off time for one of the RDFC power switches; and an output for turning on the determination A drive signal is provided to the switch with the cutoff time. In yet another related aspect of the invention, a method of controlling a resonant discontinuous forward converter is provided, the forward converter comprising a transformer having 15 polarity-matched first and second windings, and for switching to the a switch of a direct current of the first winding of the transformer, the converter further having a direct current output coupled to the second winding of the transformer, the method comprising sensing a signal from one of the controllers having one or more inputs The resonant discontinuous forward converter converts one or more signals, and analyzes the one or more sensed signals to determine a turn-on and turn-off time of the switch, and provides a driving signal according to the determined turn-on and turn-off times Give the switch. In yet another aspect of the invention, a method of operating a resonant discontinuous forward converter is provided such that the resonant discontinuous forward converter has lower sensitivity and tolerates one or more of the resonant discontinuous forward converters Resonance 17 200807849 The method comprises a power switch of a Xiang-spontaneous recorder drive _ resonance discontinuous forward converter, one of which is substantially fixed frequency 盥 one or both of which are selected when the switch is substantially i In order for the volts to make the switch turned on. 10 15 20 "This method is only used in this case, the RDFC is configured to operate in a real-to-voltage switching mode, for - different (resonant) component values. This causes a reduction - reality has a low component count and Therefore, it is potentially for the Curry County to reduce the "industry practice, (4) in this (4) a, the (main) variation of the magnetic inductance and the resonance capacitor to ensure high efficiency, thus further providing 70. - Kind to stay. - a controller of the resonant discontinuous forward converter, such that the resonance has a lower sensitivity to the conversion H and accommodates a resonant discontinuity - or more resonant components, the controller is included to drive the Photographing the continuous forward converter - the power switch - the spontaneous oscillator; the vibrator - the substantial solid frequency and - the working period of the middle, the middle = the selected 'W off is essentially at the other - tree level The towel provides a controller for the forward converter, the transformer includes a transformer having a polarity of the first and second windings, and a switch for switching to the variable - The DC of the winding - the switch 'the converter is more = 11 the second winding of the transformer _ - DC output, the controller ^ controls the forward converter to operate in a controlled oscillation mode, in the basin, with The inverter has an operation cycle including current flowing into the transformer: a conversion 18200807849 and a first (conduction) portion of the second winding, and a substantial resonance voltage waveform appearing in the first winding of the transformer and the switch One of the second connections a portion, wherein the controller has at least one sensed signal input for sensing a signal from one of the resonant discontinuous forward converters, and 5 is responsive to the sensed signal to control the switch to operate the forward direction The converter is output in one of the controlled oscillation modes. The sensed signal in the preferred embodiment is responsive to one of the energy levels in the transformer. Preferably, the controller is implemented using a switch control module having one of the first and second switch control inputs to receive individual turn-on and turn-off control signals. Preferably, these are driven by a comparator which compares the sensed signal with a reference; preferably the other is also driven by the comparator output, but delayed, in particular by a variable pulse width Timer. In this manner, the switch can be controlled to conduct, when one of the voltages sensed on the switch reaches the reference voltage, and is controlled to be turned off after a predetermined or variable time. In some of the more preferred embodiments, the cut-off control signal is also gated with an overcurrent protection signal such that when an overcurrent condition is detected, the switch can be controlled to turn off immediately. In other configurations, the on and off of the switches can be separately controlled; alternatively, the on and off of the switches can each be controlled by sensing a voltage and/or current on the RDFC input. In the embodiment, the switch is turned on for a time (which may be a fixed period of time, or may be zero) when the voltage substantially reaches zero, and/or in response to sensing the first (input) winding through the transformer A current sensing signal (voltage) of the current. In an embodiment, the switch is turned off after a fixed or variable on-time, and/or in response to a voltage sensed at the input of the RDFC and/or electricity 19 200807849 / melon in the case, the controller may respond Signaling more than one from the RDFC. In an embodiment, the RDFC lacks one of the grids in parallel with the output rectifier and instead the RDFC is assembled to achieve resonance without any capacitance other than the internal parasitic capacitance associated with the rectifier. 5 RDFC can be used in conjunction with a total power switch. In such an embodiment, a high κ C can be derived directly from the grid-like total power source, such as by a bridge rectifier, which provides an input-to-RDFC that is combined to produce a lower DC output voltage, such as less than 50V, 4〇v, 3〇v, 2〇v or ·. In some preferred embodiments, the controller of the present invention is implemented in a 10 single-chip integrated circuit, optionally including a power switch. One of the aforementioned controllers can be implemented as an analog or digital circuit. Therefore, when the controller is mainly or entirely implemented in a number circuit, the invention further provides a carrier for carrying a control code, such as a buffer (scratch transfer layer) or a system C defining hardware to implement control. Device. According to still another aspect of the present invention, there is provided a forward-to-direct power converter comprising: - an input; a transformer having a primary and a primary winding; and a combination to replace power transmission from the wheel Passing through a power switch of the primary winding; consuming one of the output of the secondary winding; and a control system having a sense wheeling and being configured to control the switch-switching clock to respond Resisting power from the forward converter from a sensed signal from the sense input; and wherein the sense input is coupled to receive the sensed signal from a primary end of the forward converter. The sensing signal providing an input to the control system may include a voltage and/or current sensing signal. The control system can adjust one of the forward power converters. 20 200807849 Output voltage and / or an output current. The present invention also provides a controller for a primary end sensing, particularly as previously described. Looking for ~ = The skilled person can understand that the aforementioned _discontinuous resonance is ::: with:: road topology, including but not limited to those described later. For example, 'Transformer can contain a brief description of the diagram... Example: Γ 这些 这些 这些 Γ Γ Γ 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些 这些To the converter example. The first ice_shows the implementation of a discontinuous resonance forward converter, respectively, and the example clock and control configuration of one of the converters of Fig. 2a; the 3a and 3b diagrams show the forward converter of Fig. 2a from _ I7〇v DC wheel 15 waveform; input supply provides 1 A and 2 A output current operation __ Example Μ · Figure 4 shows a forward converter power supply according to one embodiment of the present invention An equivalent circuit model; 5a-5d shows an alternative topology of a forward converter in accordance with an embodiment of the present invention; FIGS. 6a-6c illustrate the use of an auxiliary winding to reset a forward converter in accordance with an embodiment of the present invention. An example of a transformer. Figures 7a and 7b respectively show a forward converter that does not have and has a high frequency control waveform during startup; Figures 8a-8c show an input of a discontinuous resonance forward 21 according to one of the inventions 2008 20084949 converter embodiment Sensing connection configuration and one of the forward converters under overload and no load conditions; Figures 9a-9c show examples of late, early, and target waveform clocks of a forward converter; 5 1st The a and 10 b diagrams show the adjustment of one of the forward converters and the multiphase forward converter circuit, respectively, using the secondary side feedback; Figure 11 shows the waveform of the resonant discontinuous forward converter, which uses the pulse jump An example waveform of a switching drive pulse, a switch (collector) current, and a switch (collector) voltage is illustrated for the transition to the resonant valley; and FIG. 12 shows an exemplary resonant discontinuous forward converter The voltage sensing circuit technology, especially the chopping reduction. L Embodiment: J Detailed Description of Preferred Embodiments In this specification, we describe controlling a resonant discontinuous forward converter. 15 In an example RDFC, the power to one of the primary or input windings of a transformer is switched, and one of the secondary or output windings of the transformer matching the polarity of the primary winding is coupled to a rectifier that provides DC to a leveling capacitor The DC power is supplied to the RDFC output from this connection node. A voltage waveform on the secondary winding of the transformer has a first portion during which the switch conducts and current flows into the junction node and the second substantial resonance portion during which both the switch and the rectifier are turned off. Substantially no current flows into the connection node during the voltage waveform of the second part (except from the leveling capacitor). In design, we describe a connection between the rectifier and the connection node, which can include a small inductor (such as less than 5% of the main end magneto 22 200807849 sense) 'but the actual resonance of the second resonance part of the waveform No current flows into this inductor during this period and does not require the use of a large plug in the continuous forward converter. There is no need to connect - the capacitor crosses the rectifier to reach resonance; in an embodiment, our resonance essentially spans only the switch, not including the secondary diode. In the second embodiment, we use the magnetic inductance of the transformer with the additional grid on the main end to achieve the pachining in the off period. In some preferred practices, the RDFC is configured for AC-to-DC conversion and thus includes an AC-to-DC converter, such as one of the bridge rectifiers on the primary side. In some specific preferred practices, the RDFC^^, plug-in type 10, and the main terminal is powered by a DC voltage (such as greater than 7 (Wdc, l〇〇Vdc, 150V DC, or 200Vdc), while The secondary side DC voltage is very low (for example, less than 20V DC or lOVdc). In the embodiment, we use zero voltage switching on the main terminal (ie, a main terminal switch is used when the voltage on the switch is close to zero volts). Turn on), but we ignore the loss of the secondary diode loss at the time of switching. We will also describe the technique used to implement a resonant discontinuous forward converter (RDFC) that uses a control system in a controlled manner. Turning one of the RDFC's power switches on and off. As mentioned above, the control system can operate in an uncontrolled fixed frequency mode, or the control system can sense from a 20 or more inputs and respond to this sensing to determine when The power switch is turned on and off, for example, to implement pulse width and/or frequency modulation. This facilitates the adjustment of the RDFC, and the details can be implemented using an algorithm. A system that uses a control system to operate the RDFC compensation circuit. change And operating in a zero voltage switching (ZVS) mode. The converter can also control the switching frequency during startup and/or current limiting 23 200807849 to protect the power switch and increase the energy transferred to the load. The control system preferably utilizes a control 1 (: (integrated circuit) implementation. As mentioned before, the operation of the foot c does not require a free rotation or flyback diode n with or without an output inductor. However, if the output inductor 5 Small enough to ensure that the forward converter operates in a discontinuous mode and is substantially at or near resonance. Referring now to Figure 2a, this shows a discontinuous resonant forward converter 2()() according to the invention. Example. Figure 2b shows an example clock and control system 21〇 for the forward converter of Figure 1. 10 I test 2a® 'This display—completely resonant discontinuous mode forward converter 200' There is a DC input 202 coupled to the main winding 204 of the transformer 2〇6 of one of the series and one of the power switches 212. A resonant capacitor 214 is connected across the main winding of the press and the DC input 2〇2 is provided. Leveling capacitor write 216. Forward conversion At the output of the converter, one of the secondary windings 2〇8 of the transformer is supplied with power from a rectifier 220 to a pair of DC output terminals 218. A leveling capacitor 222 is connected across the DC output terminal 218 to the junction of the rectifier 220. The output node, the leveling capacitor 222 and one of the connections to the direct current output 218 are labeled "X." The current entering the node X flows into the leveling capacitor 222 or the positive flattening 222 and the output 218. Discontinuous, relative to the circuit shown in Figure 20. Switch 212 can include a bipolar or MOS transistor, such as a MOSFET, or IGBT, or some other device. The rectifier 22 can be implemented as a diode or by a MOS transistor. Resonant capacitor 214 may comprise a discrete component, or may be provided entirely by parasitic capacitance, or may comprise either of the two 2008 200849 combinations. The switch 212 is controlled by a controller 210. The open controller 21 includes a clock control module 210a and a switch control module 210b. The clock control module provides a switch conduction and switch off signal 210c to the switch control module 21. b. The 5-pulse control module can have one or more sensing inputs, such as a voltage sensing input and one of the current sensing inputs, or such sensing action can be omitted, and the clock control module 210a It is essentially operable independently of the sensing conditions of any forward converter circuit. Where voltage sensing is applied, the voltage across the main winding of the transformer can be sensed, either directly or indirectly. For example, the voltage can be sensed by a connection to one of the junctions between the main winding and the switch as shown; alternatively, for example, a sense voltage can be derived from one of the auxiliary windings of the transformer (not shown in Figure 2a). ). Where current sensing is utilized, this can be conveniently implemented to sense the voltage across a current sensing resistor. 15 In the circuit operation of the 2& diagram, the input DC voltage (typically relatively high) is converted to an output DC voltage (typically in the range suitable for consumer electronics), such as between approximately 5V and 20V. between. In some preferred embodiments, the DC output is isolated from the DC input, as shown in Figure 2a; other embodiments ♦ may utilize secondary side feedback, in which case a set of 2 dimmers may be included to provide A barrier to the primary and secondary ends of the converter. General forward converters have several advantages, including relatively small size and low cost. Traditionally, however, they are difficult to adjust, and components, particularly switches, are prone to failure under certain load conditions and startup. In theory, they have good performance because they operate in resonant mode, and the freewheeling or flyback diode of the conventional 25 200807849 prevents resonance. Furthermore, the traditional strike-off must be carefully selected to allow self-resonant component values, but this limits the use tolerance of the components, which is more expensive and increases manufacturing difficulties. Our configuration utilizes a controller 210 to control the clock and cutoff of switch 212, which also allows for the use of a variety of advantageous techniques. Therefore, we will explain below how the forward converter of the first graph can operate under the sinus of a component value range. 'The current limit and start control are operated if both are helpful to achieve reliable operation and protection switch 212. ), and switching the clock 1〇 if the control is reached in a discontinuous resonance mode. Figure 2b illustrates an exemplary embodiment of the controller 21A of Figure 2a. A comparator 250 compares a sense voltage to a reference voltage, such as zero volts, to provide a control signal 252 to a switch control unit 256 to control the switch 212 to conduct. The output of the comparator 250 is also provided to a timer 258 whose clock begins at 15 a pulse width. A signal is provided on a second control line 254 to the switch control unit 256 to control the switch 212 to turn off when the timer is paused. Switch control unit 256 can include, for example, a set_reset latch and an interface circuit to drive the base of a bipolar transistor, and/or the gate of a MOS transistor. Preferably, the circuit also includes a R gate 260 and an input 262 from an overcurrent protection line 20. This can be produced by comparing a current sense input with a reference level defining a current limit threshold. When the overcurrent protection input 262 becomes active, the switch control unit 256 is immediately turned off by the control switch 212, so the implementation of the inter-period current limit control 3a and 3b shows the operation of the forward converter of the second diagram. 200807849 Example waveform. In these figures (and similar figures), waveform 300 indicates that the drive voltage turns on the base of a bipolar transistor switch, and waveform 3〇2 shows a collector current 'which is substantially equal to the transformer via forward converter 200 A current of one of the main windings 204 of 206. The main terminal current thus controls the amount of flux in the transformer 2〇6 and thus also the secondary side current. Waveform 304 shows a voltage at the collector extreme of the bipolar transistor switch. When the switch is turned on, the voltage equal to the voltage across the main winding 204 of transformer 2〇6 is reflected on the secondary winding 2〇8 of the transformer. When the switch is turned off, the current in the main terminal of the transformer drives one of the secondary ends, so the leveling capacitor 222 is charged via the rectifier 220; when the 10th opening is turned on, the main end of the forward converter stops driving the secondary side. Power is supplied from the leveling capacitor 222 to the output 218 (and the diode 220 is turned off). In the waveforms of the maps 3a and 3b, the scale of the waveform 300 is 500 mv for each portion, the waveform 302 is for each portion of the mA, and the waveform 304 is for each portion of 100 V. The driving waveform frequency in Fig. 3a is nearly 59 kHz; the driving waveform in Fig. 3b has a frequency of 5 4.8 ΚΗζ. The near observation of waveform 300 shows that the cutoff of the drive signal is not completely removed due to the characteristics of the bipolar switch; waveform 302 corresponds to 3〇4. In the preferred embodiment of the forward power converter, we describe After the transfer, the periodic transformer is reset (so it is not magnetized). During the reset period, the phase current flows into the main winding of the transformer in the opposite direction when the switch 212 (generally a power transistor) is turned on. The inductive resonance action of the transformer And the valley state 214 is used to perform the reset switch 212. Once turned off, there is a half-down wave in the chassis of the capacitor 214 (waveform 3〇4). The voltage on the chassis drives the power supply voltage by the action of the inductor. The top of the oscillometric voltage 27 200807849 of the transformer is mainly opposite to the direction of the forward energy transfer. (At this point a relatively high voltage is on the switch 212. The example waveform 304 of the 3a diagram is nearly 550V, which is much larger than the input voltage. And the switch is therefore able to withstand such a voltage without collapse.) When the capacitor discharges and the voltage on switch 212 returns to 0 5, the current in the transformer is mainly One of the source supply periods is reversed in the forward direction of the energy transfer portion, so the transformer is reset. If the switch is not turned on at this time, the resonance continues to decrease the formant string (see Figure 11 below). The ground switch 212 is turned on when the voltage on the switch is substantially small, that is, close to 0V (Fig. 3; Fig. 11). 10 Fig. 4 shows one of the discontinuous resonant forward converters for Fig. 2a. Equivalent circuit. This shows the bipolar transistor switch, the output rectifier, the parasitic capacitance (Cp) of the transformer, and the resonant capacitor (Cr), a magnetizing inductance (Lmag), which represents the energy stored in a transformer, and a leak. Inductance (Lleak), which represents the leakage inductance 15 between the primary and secondary windings of the transformer (from the leakage of some flux lines to the primary and secondary windings such that they act as an inductor). Usually, but not necessarily Cr is much larger than Cp. In operation, L mag keeps the main current flowing into C r to cause resonance, while the secondary current nearly matches the main current. The leakage inductance provides a current limit, which is especially helpful in leveling. When the container is in a short-circuit state, the overload at startup is reduced. 20 Figures 5a to 5d show an alternative topology of the resonant discontinuous forward converter. The resonant capacitor in Figure 5a is coupled to the switch (in this example) , shown as a bipolar transistor switch. The resonant capacitor in Figure 5b is at the output of the converter, more particularly the secondary winding connected to the transformer. Figure 5c clearly includes a series connection with the output rectifier. A small inductor. Figure 5d 28 200807849 shows a forward converter structure in which an automatic transformer is used. In an embodiment, the transformer is reset by the resonant portion of the transformer waveform: to discharge magnetization to resonance The transformer of the current in the capacitor is demagnetized and discharged resonantly. Alternatively or alternatively, the transformer can be reset by means of one of the couplings in series with a rectifier. Figure 6a shows an example of such a reset circuit in which one of the primary end auxiliary windings has a relative or opposite polarity to the primary and secondary windings of the transformer. During the off-period of the switch, a diode in series with the auxiliary winding becomes forward biased and conducts power back to the DC input (making the technique non-dispersive). The still and 6〇10 diagrams show alternative combinations in which the auxiliary winding is placed on the secondary side of the transformer and (again) has one polarity opposite the primary and secondary windings (the secondary side is connected to the diode) To the opposite side of the winding). In these examples, the auxiliary winding is connected in series with a rectifier and across the secondary winding and rectifier, and selectively connects the inductor to the output of the forward converter. 15 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ If there is sufficient delay, further resonance can finally be seen in waveform 3〇4, but it should be understood that the switch may be quadruple again by mi ^' so the control of the switch can be detected by the waveform 30 - substantially zero The voltage level and after its resonant half period, then wait - delay (which can be zero) before turning the switch on. The tolerance of this circuit operation is based on zero-voltage or resonant wave valleys, allowing __ (more specifically, switching off) to be long enough to cope with the resonance solution range and the resonant component value. 29 200807849 We next consider the start of the forward converter. The power supply output appears to be shorted at startup. Unlike a continuous forward converter, which uses a flyback diode' based on the load appearing on the RDFC, the insufficient amount of energy can be transferred to the converter's wheel to charge the output capacitor. This is especially a problem with the current 5 limit because ultra-high currents can occur at the main end of the transformer, while current limiting allows the switch to turn off the drive signal, allowing the output capacitor to be charged with a specific load. Figure 7a shows the difficulty of not being able to rise to the correct value during startup of the power supply output (voltage) by current limiting. The view of the collector voltage waveform 1 〇 also clearly shows that when the start-stop (because the secondary output is retroreflected) has a non-destructive component, and this non-zero collector voltage can be sensed to identify this start condition, as well as current limit , overload, and short circuit, if desired, in a preferred embodiment of the discontinuous resonant forward converter, the forward converter is controlled to operate in the frequency mode when activated, such as to operate 5 or 1G times the rate of positive b. This II can be implemented by selecting at the start-up - a simple vibrator that senses the collector voltage and is used to control the switch conductance to the higher-frequency board type. By - increasing the frequency of operation · c will increase the transfer output ^ * while still tilting the power supply. Figure IF (4) This increase operation (time division is shorter than the first _ Bay rate θ f), and can be found at this high frequency. (4) The time for bribery is (4) Change to the output voltage of normal operation. The system then describes the current limit for the discontinuous resonance forward transition 11, which operates in a resonant mode RDFC once it is activated and reaches steady state operation 30 200807849, with the accompanying input (voltage) - Output (electric castle). However, if a = planting is applied, especially (d) at a fixed frequency, the output current and switching current will increase significantly and the circuit may be damaged. Therefore, it is desirable to sense the switching current in the RDFC and the controller that we have described, which can shorten the drive current to control the drive current under an overload condition. The _display-RDFC-embodiment includes a controller having a current sense terminal (8) and a collector voltage (Sc) and a DC input voltage (sdc) sense input. Figure 8b shows the waveform of the forward converter during the load period, in which it can be found that the collector voltage waveform is no longer 由于 due to the output circuit load) correctly resonating (the first part of the half period is truncated). For comparison, the & graph shows one of the forward converters under no load conditions. We have previously explained how to implement overcurrent protection. In some cases, however, the next fixed current limit converter reduces the power transferred to the output, which in turn reduces the output voltage and increases the output current, which causes the converter output 15 voltage to drop significantly, even when the load is removed. In this case, the forward converter may not be able to recover. Strategies to address this or more issues can be applied. For example, the increased frequency restart technique can be used to effectively return the output voltage to its normal operating level as previously described. Alternatively or alternatively, an output inductor can be used, and/or the transformer's vapor inductance can be controlled to provide a current limiting effect. Again, the current limit can be varied to increase the current limit as the pulse width decreases. The latter approach will be explained in more detail later. More than 5 sheep, in some applications, such as a certain current load, the output voltage can enter a state of continuous decline, and the power supply in this state is not 31 200807849 In this way, in the same way as before, this is added during startup. The power to the load can be increased, thus increasing the turn-off voltage. : ', the shank can also limit the current at the same time to reduce the round-out or - series inductance can also be used to discard a part of the output of the electric power. This power is only 10 pulse 2-way converter when operating in a current limiting mode It is possible to adjust the wheel current by increasing the allowable switching current with the decrease. This I is safely implemented in the -RDFC type we have described, as the risk of injury conversion decreases with pulse width. Combined with this technology and the leakage inductance of the transformer and / or - series output inductance can make the output current with the output voltage = is pulled. Therefore, in general, the efficacy of this technique is to increase the pulse visibility to cause a reduced current limit. We now move forward to a technique that can be used to compensate for the use of components that have a relatively wide tolerance. It is very difficult to manufacture a 15 - transformer with a small tolerance for the main magnetizing inductance. One of these technologies removes and clings to the core, but this technique is expensive. A small tolerance resonant capacitor is also expensive. We have described how a fixed frequency vibrator in the controller can be used with the appropriate duty cycle selection to compensate for the increased tolerance in these components. Another technique involves compensating for increased tolerance by controlling the switch to be turned "on" during the zero (20) voltage phase of the primary (voltage) waveform. As mentioned above, there is a final time limit when the switching voltage is near zero volts (in reality, the voltage can be slightly lower than the ground potential). In the Zero Voltage Switching (ZFS) embodiment of the controller, the power switch is turned "on" during this time. The first to the present diagram shows the example clocks of different switch drive related collector voltage waveforms. 32 200807849 Referring to Figure 9a, this shows an example, but the open _ ideal state is turned on late. "This is better to switch, turn on, as shown in Figure 9b, which can cause too early loss of non-7 switch and electromagnetic interference. The first figure shows the second: 'The preferred clock that causes the switching voltage waveform. Sample_There is a set of poles perfect 10 15 20 The first reading (10) pulse is achieved by the next money line (four): In the collector pole μ material (four) and let the switch respond to this and lead to the pole power to zero , or after the voltage reaches zero _ small segment _, ^ = collector voltage starts to climb again. The clock of the 9th figure shows _ "the clock of the resonance switch, its switch as long as the collector power _ reaches zero, then we Next, we discuss the regulation of the output voltage of an RDFC. The effect is very poor, and it is relatively high in the inductance and the resistance of the component (winding). This result is the output of the electric power. - RDFC may have difficulty in compensating for input voltage variations, and usually the output voltage is chasing the input voltage. This is a problem in the forward converter that flows out of the grid-like total power supply because of the total voltage. Will vary greatly from time to time. However, the aforementioned controller implementation is suitable for pulse width and pulse wave frequency. Rate Control = Compliance to adjust the -RDFC output voltage. More specifically, the adjustment can be improved in the case of low wheeling or A-load conditions - or by increasing the pulse width and increasing the frequency of the field. Figure l〇a shows another - Can be used for output voltage regulation technology. In this configuration, '-input voltage transfer ·, whether it is - AC transfer or - DC transfer ^ conversion $, to provide _ DC input power supply to the forward direction, and It is fed back from the secondary side of the forward converter. To regulate the output 33 200807849 voltage, the wheel-in converter can include a - boost or buck or PFC (power factor correction) stage. Figure 10b shows the - multiphase Two power transformers are used in the assembly to improve the wheel-out adjustment. In the configuration of the i-th diagram, the switches are controlled so that the 5 switches are driven only when the other switches are off, creating complementary but non-overlapping drive waveforms. This technique is useful for small forward converters that operate at relatively high frequencies and are poorly regulated. Referring to Figure 11, we now describe some techniques for implementing low load and/or standby mode operation of an rdfc. In a preferred embodiment, I use pulse-hopping technology. A RDFC power supply operating at maximum frequency is traditionally inefficient at low loads and has high standby power loss. Therefore, when the load on an rdfc is reduced, the efficiency is reduced, especially in The performance is low at no load. This is mainly caused by high switching loss and high magnetizing current, etc. However, by controlling 15 turn-on and turn-off time, power loss can be reduced, especially by using the aforementioned PWM and PFM techniques, or In addition, the pulse of one cycle is jumped to a cycle equal to many times. It is also better to control the clock of these pulse waves to synchronize with the valleys in the resonance waveform, so that the RDFC switch after the trough resonance 0 is therefore in our system. In practice, we reduce the width of the pulse by limiting the switch before defining a shorter pulse, which reduces the load power loss. Additionally or alternatively, we cite a delay for the next pulse to make the switch turn on more slowly, skipping one or more switches to drive the pulse. This is also illustrated in Figure 11 where the drive pulse is delayed to skip one or more resonances. 34 200807849 Cycles As indicated by the switch (collector) voltage in the legend. When turned on, the zero-volt switch (collector) current has a sharp point in the zero-volt switch (collector) of the resonant switch waveform, and the eleventh figure also switches between the non-resonant valleys, wherein the switch is V-passed at the valley point of the resonant waveform to reduce the loss. . These techniques may be implemented to control 5 as in one of the foregoing: by a sensing configuration as shown in Figure 8a, or alternatively using voltage sensing as shown in Figure 12, for example, using Figure 2b. One of the control configurations. A reduced power mode, such as a pulse width modulation (decrease) or pulse skip mode, can be triggered by an event, such as - or more controller (wafer) power supply drops below a predetermined value; After the second resonance (see _) 10, or after a predetermined time (between the drive pulses). One of the pulse skipping techniques in the RDFC, such as the aforementioned, increases efficiency and reduces power loss at low loads or during standby. Pulse skipping technology also responds quickly at low loads. In yet another technique, the system practice we use, particularly in package 15 with a (bipolar) transistor switch, is used to limit the switching current rather than operating the transistor in the -linear region. This prevents the switch from overheating. In practice, when the switch is cut off, the main terminal voltage on the switch has a sudden rise, which can be sensed and controlled. 4 The overshoot is limited by the conduction of the crystal. Thus, for example, the switch can be partially turned on during startup to compensate for and limit voltage overshoot. 20 We next describe some of the chopping removal techniques that apply to an off-line (plug-in) RDFC converter. Referring to Fig. 12, this shows how a total chopping voltage can be sensed in a resonant discontinuous forward converter. As can be seen, the input voltage chopping can be sensed from a number of points, including the input DC bus, collector voltage, a transformer winding voltage, and/or output voltage. a small amount in the embodiment 35 200807849

The total chopping voltage is fed into the clock control circuit to change the ^^", and / or pFM apostrophes, and then the chopping is performed by adjusting the input chopping voltage. The operating frequency of rdfc is much higher than 50ΗΖ*60Ηζ Chopping, and thus the clock control circuit can track the compensating line wave 5 effect in a manner similar to controlling the DC output voltage. Roughly speaking, we have illustrated the use of a controller to analyze one or more inputs and determine one A resonant discontinuous forward converter that provides a drive signal for the turn-on and turn-off times of the power switch (only a simple fixed frequency/duty cycle drive can be used in a simple system). Pulse width and/or frequency 10 rate It can be adjusted according to the resonance circuit, or the sensing signal input to the controller or by a spontaneous oscillator can be used to alleviate the problem of the resonance member. Preferably, the maximum energy is passed through the RDFC without compromising the resonance effect and increasing Loss, the controller is configured to implement zero (switching) voltage switching. Preferably, the control system is configured to terminate a 15 pulse of a conducting pulse when an overcurrent condition is detected. The protection circuit (switch), and/or the load. Preferably, the RDFC embodiment uses an increased frequency to assist in the rise of the output voltage during startup and/or current limiting. PWM and PFM techniques can be employed to improve load and line regulation. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows an example of a conventional forward converter. 20 The first and second figures show an embodiment of a discontinuous resonant forward converter, respectively, and an example of a converter of Figure 2a. Pulse and control configuration; Figures 3a and 3b show the example waveform of the forward converter of Figure 2a from a 17 〇v DC input supply during the output current operation of 1A and 2A respectively; 36 200807849 Figure 4 shows the basis One of the embodiments of the present invention is an equivalent circuit model of a forward converter power supply; Figures 5a-5d show an alternative topology of a forward converter in accordance with an embodiment of the present invention; 5 6a-6c The figure shows an example of resetting a transformer of a forward converter using an auxiliary winding according to an embodiment of the invention. Figures 7a and 7b respectively show that a forward converter does not have and has a south frequency control during startup. Waveforms, Figures 8a-8c show the input sense connection configuration of one embodiment of the discontinuous resonance forward 10 converter according to the invention and one of the forward converters under overload and no load conditions; 9a- Figure 9c shows an example of the late, early, and target waveform clocks of a forward converter; Figures 10a and 10b show one of the forward conversion 15 and the multiphase forward converter, respectively, using the secondary side feedback. Circuit adjustment; Figure 11 shows the waveform of the resonant discontinuous forward converter, which uses pulse skip and resonant valley switching to illustrate a switch drive pulse, a switch (collector) current, and a switch (collector Example waveform of voltage; and Fig. 12 shows an exemplary voltage sensing circuit technique of a resonant discontinuous forward converter, especially chopping reduction. [Main component symbol description] 101 DC input 109 main winding 102 DC input 110 transformer 105 switching device 111 secondary winding 37 200807849 113 capacitor 212 power switch 114 rectifier 214 resonant capacitor 115 diode 216 leveling capacitor 117 output plug 218 DC output Terminal 119 Leveling capacitor 220 Rectifier 121 DC output 222 Leveling capacitor 122 DC output 250 Comparator 200 Discontinuous resonance forward converter 252 Control signal 202 DC input 254 Second control line 204 Main winding 256 Switch control unit 206 Transformer 258 Timing 208 secondary winding 260 OR gate 210 control system 262 input 210a clock control module 300 waveform 210b switch control module 302 waveform 210c switch conduction and switch cutoff signal 304 waveform number 38

Claims (1)

200807849 X. Patent Application Range: 1. A discontinuous resonant forward converter for converting an input DC voltage into an output DC voltage, the converter comprising: first and second DC inputs; 5 - a transformer having a primary and secondary winding of polarity matching; a controllable switch for switching power from the primary input of the DC input through the transformer, the controllable switch being coupled in series with the primary winding of the transformer Between the first and second DC voltage inputs; 10 first and second DC voltage outputs; a rectifier coupled to the secondary winding of the transformer, the rectifier being coupled in series with the secondary winding of the transformer Connected between the first and second DC voltage outputs; a leveling capacitor having a first connection node coupled to receive a DC power from the rectifier at a first connection node 15, the first connection a node coupled to the first DC voltage output, the leveling capacitor having a second connection coupled to the second DC voltage output; and having a coupling a controller to the controllable switch and configured to control the output of one of the switches such that a voltage waveform 20 on the secondary winding has a first period during which the switch is conducting and current flows into the first connection node And having a second substantial resonant portion during the off period of the switch; and wherein substantially no current flows into the first connection node during the second portion of the voltage waveform. 39. The method of claim 1, wherein the connection between the rectifier and the first connection node has an induction coil, and wherein substantially during the second portion of the waveform No current flows into the induction coil. 5. A forward converter as claimed in claim 1 which is not coupled to a freewheeling rectifier of the secondary winding of the transformer. 4. The forward converter of claim 1, wherein the controller includes a substantially fixed frequency oscillator for providing a switch drive signal to the controller output, the switch drive signal having control for the switch a turn-on period for turning on power to the main winding, and a cutoff period for controlling the power of the switch to be turned off to the main winding, and wherein the drive signal cut-off period is long enough for the secondary winding voltage waveform The resonant portion substantially comprises a half substantially sinusoidal resonant period and is short enough that substantially no additional sinusoidal resonant period occurs during the deadline. 15 5. The forward converter of claim 4, wherein the substantially fixed frequency oscillator has an on period: a cutoff period of less than 1.5: 2.0 one duty cycle. 6. The forward converter of claim 5, wherein the substantially fixed frequency oscillator has an on period: a cutoff period greater than 0.5: 2.0 of one of 20 cycles. 7. The forward converter of claim 1, wherein the controller is configured to provide a switch drive signal to the controller output, the switch drive signal having control for opening the switch to the primary winding a turn-on period of power, and a deadline for controlling the switch to turn off the 40 200807849 power to the primary winding, and wherein the controller is configured to use a first control signal to initiate the drive signal conduction period, and A second control signal is used to initiate the drive signal deadline. 8. The forward converter of claim 7, wherein one or both of the first and fifth control signals are responsive to an energy level within the transformer. 9. The forward converter of claim 7, wherein the first control signal is responsive to a voltage on the primary winding or an auxiliary winding of the transformer. 10. The forward converter of claim 9, wherein the first control signal initiates the drive signal conduction period in response to a value of substantially zero volts on the primary or the auxiliary winding of the transformer. The drive signal conduction period is initiated in response to a prediction of a value of substantially zero volts on the primary winding of the transformer. 15. The forward converter of claim 8 wherein the drive signal deadline is long enough for the resonant portion of the secondary winding voltage waveform to comprise a substantial half cycle of a substantially sinusoidal resonant period, wherein The first control signal identifies one of the terminating ends of the half cycle, and wherein the controller initiates the drive signal 20 conduction period after the delay from one of the terminating ends of the half cycle. 12. The forward converter of claim 7, wherein the first control signal is responsive to a voltage on one of the auxiliary windings of the transformer. 13. The forward converter of claim 7, further comprising a timer triggered by the first control signal to control the second control signal. 41. The method of claim 7, wherein the second control signal is responsive to a voltage on the primary winding of the transformer or a voltage on one of the auxiliary windings of the transformer. 15. The forward converter of claim 7, wherein the first control 5 signal is responsive to a current sense signal responsive to a current flowing through the switch when the switch is turned on. 16. The forward converter of claim 7, wherein the second control signal is responsive to a current sense signal responsive to a current flowing through the switch when the switch is turned "on". 10 17. The forward converter of claim 4, further comprising a current sensor for sensing a current flowing through the switch, and wherein the controller is configured to respond to the sense of current from The detector indicates that the signal is turned on by a signal that is greater than one of the threshold currents flowing through the switch. 18. The forward converter of claim 15 wherein the controller package 15 includes a system for controlling the output to the switch such that the operation is increased in response to the implementation of the current sense signal or current limit. One of the frequencies of the drive signal. 19. The forward converter of claim 1, wherein the controller includes a system for controlling the output to the switch such that one of the drive signals is added to the switch during startup of the converter 20 frequency. 20. The forward converter of claim 1, wherein the controller includes a system for controlling the output to the switch such that during startup of the converter, the converter operates in a non-resonant mode under. 21. The forward converter of claim 1, wherein the controller system 42 200807849 is configured to sense a voltage on the primary winding of the transformer or an auxiliary winding of the transformer and is responsive to The primary or auxiliary winding voltage sense is adjusted to one or both of the drive pulse width and the pulse frequency of one of the switches. 5 22. The forward converter of claim 1, wherein the controller comprises a single integrated circuit. 23. An integrated circuit comprising a forward converter as defined in claim 22 of the scope of the patent application. 24. A controller for controlling a forward converter, the forward converter converting 10 an input DC voltage into an output DC voltage, the converter comprising: first and second DC inputs; having polarity matching a transformer of primary and secondary windings; a controllable switch for switching power from the DC input through the primary 15 winding of the transformer, the controllable switch being coupled in series with the primary winding of the transformer Between the first and second DC voltage inputs; a first and a second DC voltage output; a rectifier coupled to the secondary winding of the transformer, the rectifier 20 being coupled in series with the secondary winding of the transformer Between the first and second DC voltage outputs; and a leveling capacitor coupled to receive a first connection of a direct current from the rectifier at a first connection node, the first connection node being coupled To the first DC voltage output, the leveling capacitor has a second connection of 43 200807849 coupled to the second DC voltage output; and wherein the control Having a controllable switch coupled to control an output of the switch such that a voltage waveform on the secondary winding has a first portion during the switch being turned on and current flowing into the first connection node And having a second substantial resonance portion during the off period of the switch; and wherein substantially no current flows into the first connection node during the second portion of the voltage waveform; whereby the forward converter can be The controller controls to operate in a 10 discontinuous forward voltage conversion mode. 25. An integrated circuit comprising the controller as defined in claim 24 of the scope of the patent application. 26. A method for controlling a forward converter, the converter comprising: first and second DC inputs; 15 a transformer having a polarity matching primary and secondary winding; for switching from the DC input a controllable switch of the power of the main winding of the transformer, the controllable switch and the main winding of the transformer being coupled in series between the first and second DC voltage inputs; 20 first and second DC voltages An output coupled to one of the secondary windings of the transformer, the rectifier and the secondary winding of the transformer being coupled in series to the first and second DC voltage outputs; and having a coupling coupled to a first connection Receiving, at the node, a leveling capacitor from a first connection of the DC power of the rectification 44 200807849, the first connection node being coupled to the first DC voltage output, the leveling capacitor having a coupling to the second DC One of the voltage outputs, the second connection, the method includes controlling the controllable switch such that a voltage waveform of one of the secondary windings is turned on and current is flowing at the switch Having a first portion during the first connection node and a second substantial resonance portion during the off period of the switch; and wherein substantially no current flows into the first connection during the second portion of the voltage waveform node. 10. The forward converter of claim 1, wherein the voltage waveform on the secondary winding has a second substantial resonant portion during the switching of the switch and the rectifier. 28. The controller of claim 24, wherein the voltage waveform on the secondary winding has a 15 second substantially resonant portion during the period in which both the switch and the rectifier are turned off. 29. The method of claim 26, wherein the voltage waveform on the secondary winding has a second substantial resonant portion during the switching of the switch and the rectifier. 30. A control 20 for a resonant discontinuous forward converter (RDFC), the forward converter comprising a transformer having polarity-matched first and second windings and for switching direct current to the transformer a switch of the first winding, the converter further having a DC output coupled to the second winding of the transformer, wherein the controller has two modes: a first operating mode, where the first operating mode The switch is controlled to 45 200807849 to switch the DC power substantially at a frequency synchronized with the resonant frequency of one of the RDFCs, such that the RDFC is powered from the DC, and the second (reduced power) mode of operation, During this second mode of operation, the drive of the switch is controlled to increase the time ratio during which the switch is turned off. The controller of claim 3, wherein the switch drive comprises a pulse duration, during which a switch on time is determined, and /, in the second mode of operation The device is configured to reduce the duration of one of the pulses. 32. The controller of claim 3, wherein the controller is configured to control the switch to be switched to the -clock, and the clock is synchronized with one of the resonant frequency periods of the money; and In the Sigma mode of operation, the switch is controlled such that one or more of the resonant frequency periods are skipped. 15 33. The controller of claim 32, wherein the controller is configured to control the switch such that after the switch is skipped after - or more of the cycle, when the switch is subsequently controlled to be turned on, The turn-on is timed to be substantially synchronized with one of the turning points of one of the resonant waveforms of the 谠RDFC. 34. The controller of claim 3, wherein the controller is configured to reduce the condition of the load to select the second mode of operation in response to the sensing. ^ 35. The controller of claim 34, wherein the controller has a voltage sensing input for sensing a signal from the output of the output and the system is assembled from the sensed The signal identifies the reduced load bar 46 200807849 pieces. 36. The controller of claim 34, wherein the controller has an input for receiving a signal from one of the auxiliary windings of the transformer and is configured to identify the reduced load in response to the auxiliary winding signal 5 conditions. 37. The controller of claim 34, wherein the controller has a controller power supply and the system is configured to sense the reduced load condition from the power supply. 38. The controller of claim 34, wherein the controller is configured to select the second mode of operation in response to detecting more than one resonance during a period in which the switch is turned off. 39. The controller of claim 34, wherein the controller is configured to select the second mode of operation in response to one of the switches being off-duration for a duration greater than a threshold duration. 1540. The controller of claim 30, wherein the controller is configured to control the drive of the switch such that the switch conducts only when one of the voltages of the switch approaches zero volts. 41. The controller of claim 30, wherein the controller is configured to control actuation of the switch such that the switch is substantially conductive at a turning point of a resonant waveform of the RDFC. 42. The controller of claim 30, wherein the second mode of operation comprises a standby mode of the RDFC. 43. A controller for a plug-in resonant discontinuous forward converter (RDFC), the forward converter comprising a transformer having a polarity-matched first and second winding 47 200807849, and for switching to a switch of the direct current of the first winding of the transformer, the converter further having a direct current output coupled to the second winding of the transformer, and wherein the direct current to the first winding is derived from a total power supply And comprising one component of the total chopping, 5 the controller comprising: a chopper sensing input for sensing the total chopping wave; and coupling to the chopping sensing input and having control for the a clock control module outputting one of the driving signals of the switch, the driving signal comprising a pulse having a pulse waveguide for driving the switch to conduct and a pulse cutoff period for driving the switch to cut off by 10; And wherein the clock control module is configured to responsive to the sensed total chopping to change one or both of a width and a frequency of the pulse wave for suppressing the chopping in the DC output 10% Share. 44. The controller of claim 43, wherein the chopper sensing input 15 is configured to sense an output voltage of the RDFC. 45. The controller of claim 43, wherein the chopping sensing input is configured to sense a voltage of the switch. 46. The controller of claim 43, further comprising at least one second sensing input coupled to the clock control module for sensing a voltage of one of the switches 20 and passing the switch One or both of a current; and wherein the clock control module adjusts the DC output in response to a signal on the second sense input. 47. The controller of claim 43, further comprising a switch control module coupled to the output of the 48 200807849 pulse control module to provide a drive control signal from one of the clock control modules A drive signal to the switch. 48. Plug-in RDFC, which is used in conjunction with a controller as defined in Section 43 of the patent application. 49. A method for suppressing chopping in a plug-in resonant discontinuous forward converter (RDFC), the forward converter comprising a transformer having polarity-matched first and second windings, and for switching a switch to the direct current of the first winding of the transformer, the converter further having a DC output coupled to the second winding of the 10 transformer, the method comprising: sensing a total of one of the signals of the RDFC One component of the wave; and one or both of a pulse width and a pulse frequency controlled to drive the signal of one of the switches to suppress the chopping. 50. A control device for a resonant discontinuous forward converter (RDFC), the RDFC comprising a transformer and a power switch for switching to the DC power of the transformer, wherein the controller is assembled Limit one of the currents in the switch during the RDFC startup. 51. The controller of claim 50, wherein the switch comprises a transistor, and wherein the limiting comprises operating the transistor in a non-linear region 20. 52. The controller of claim 50, wherein the controller is configured to limit the current to one of the control signals of the switch during the startup. 53. A method for controlling a resonant discontinuous forward converter (RDFC) 49 200807849 method, the RDFC comprising a transformer and a power switch for switching to the DC power of the transformer, the method comprising starting at the RDFC Limit one of the currents in the switch to control the overvoltage. 54. The method of claim 53, wherein the switch comprises a transistor 5, and wherein the winding comprises operating the transistor in a non-linear region. 55. The method of claim 53 is Wherein the limit includes increasing the frequency of the switch drive during the startup. 56. A control device for a resonant discontinuous forward converter (RDFC), the RDFC comprising a transformer and a power switch for switching to the DC power of the transformer, wherein the open relationship is configured to switch Power to one of the windings of the transformer, wherein the controller includes a system for sensing a voltage in the winding of the transformer and controlling the portion of the switch to conduct in response to the sensing. 15 57. A method for controlling a resonant discontinuous forward converter (RDFC), the RDFC comprising a transformer and a power switch for switching to the DC power of the transformer, the method comprising sensing the transformer A voltage on the winding and controlling the switch are partially turned on in response to the sensing to limit the overvoltage. 20 58. A current limiting method in a resonant discontinuous forward converter, the forward converter comprising a transformer having one of a first and a second winding having a polarity matching, and the first to switch to the transformer a switch of direct current of a winding, the converter further having a DC output coupled to the second winding of the transformer, the method comprising detecting a current limiting condition; 50 200807849 and increasing to one of the switches in response to the detecting A frequency of the control signal. 59. A controller for a resonant discontinuous forward converter (RDFC), a transformer having a polarity matched first and second windings, and 5 for switching to the first winding of the transformer a switch of direct current, the converter further having a DC output coupled to the second winding of the transformer, the controller comprising: means for detecting a current limiting condition; and responsive to the detecting being added to the switch A device that controls a frequency of a signal. 10 60. A controller for a resonant discontinuous forward converter (RDFC) having one or more signals for sensing one or more signals from the resonant discontinuous forward converter Input, the controller further comprising: a system for analyzing the one or more sensed signals for determining a turn-on and a turn-off time for one of the RDFC power switches; and an output 15 for turning on the determination A drive signal is provided to the switch with the cutoff time. 61. The controller of claim 60, wherein the controller is configured to implement zero voltage switching for the switch. 62. The controller of claim 60, wherein the controller is configured to terminate one of the drive signals when an overcurrent condition is detected. 63. The controller of claim 60, wherein the controller is configured to increase the frequency by using one of the drive signals during one or both of starting and a current limiting condition. 51 200807849 64. The controller of claim 60, wherein the controller is configured to utilize one or both of pulse width modulation and pulse frequency modulation. 65. The controller of claim 64, wherein the controller is configured to adjust one or both of a pulse width and a pulse frequency of the one of the drive signals in response to the one or more sensed signals. By. 66. The controller of claim 65, wherein the controller is configured to reduce the duration of driving one of the pulses by one of the converters in response to detecting that one of the converters reduces load conditions . 67. The controller of claim 65, wherein the RDFC is plugged into a 10, wherein the sensed signal comprises a total chopping wave, and wherein the controller is configured to adjust the pulse width and the pulse wave frequency. One or both of them suppress the chopping. 68. A method of controlling a resonant discontinuous forward converter, the forward converter comprising a transformer having polarity-matched first and second windings, 15 and a first winding for switching to the transformer a switch of direct current, the converter further having a direct current output coupled to the second winding of the transformer, the method comprising sensing a discontinuous forward from the resonance using a controller having one or more inputs One or more signals of the converter, and analyzing the one or more sensed signals to determine the turn-on 20 and the off time of the switch, and providing a drive signal to the switch according to the determined turn-on and turn-off times. 69. A method of operating a resonant discontinuous forward converter such that the resonant discontinuous forward converter has lower sensitivity and tolerates one or more resonant members of the resonant discontinuous forward converter, the method Including the use of 52 200807849 a spontaneous oscillator to drive one of the resonant discontinuous forward converters of the power switch 'the oscillator - the substantial fixed frequency and - the working period of the - or both are selected, when the _ on the real f The switch is turned on when it is zero volts. 5 70 - a controller for controlling - a resonant discontinuous forward converter such that the resonant discontinuous forward converter has lower sensitivity and tolerates the resonant discontinuous axis transition H - or more resonant components The controller includes a self-oscillating oscillator for driving a power switch of the resonant discontinuous forward converter; and wherein the oscillation! ! The substantial fixed frequency 1 〇 and - the duty cycle or both of them are selected, and the switch is turned on when the switch has zero volts on the solid. 71. A resonant discontinuous forward converter comprising the controller as defined in claim 7 of the patent application. . 72. A controller for a resonant discontinuous forward converter, the forward converter comprising a transformer having a polarity-matched first and second windings, and the switch for switching to the transformer a switch of direct current of a winding, the converter further having a direct/;, L output coupled to the second winding of the transformer, the controller being configured to control the forward converter operation, In the controlled oscillation mode, wherein the converter has an operation cycle, including a current flowing into the first and second windings of the transformer, and a substantial resonance voltage waveform appears in the transformer a second (off) portion of the first winding connected to one of the switches, and wherein the controller has at least a sensing signal for sensing a signal from the resonant discontinuous forward transition Inputs, and 53 200807849, are operative to control the switch to operate one of the outputs of the forward converter in the controlled oscillation mode in response to the sensed signal. 73. The controller of claim 72, wherein the sensed signal is responsive to an energy level in the transformer. 5 74. The controller of claim 72, comprising a switch control module having first and second switch control inputs, configured to receive and control one of the switches to switch the clock and respectively turn off the first and the first A second clock signal, and a switch control output for controlling one of the switches, and wherein at least one of the switch control inputs is coupled to receive one of the signals derived from the sense signal input. 75. The controller of claim 74, further comprising a comparator coupled to the at least one of the sense signal input and the switch control inputs for ratioing the sensed signal to a reference value And providing an output that controls the turn-on and turn-off of at least one of the switches. The controller of claim 75, further comprising a timer coupled to the output of the comparator for providing an output that controls one of the on and off of the switch. 77. The controller of claim 74, further comprising an overcurrent protection (OCP) system having an OCP input and an output coupled to the control input of the second switch 20 to detect a The switch is turned off during overcurrent conditions. 78. The controller of claim 72, wherein the sensed signal comprises a signal derived from the resonant voltage waveform. 79. The controller of claim 78, wherein one of the switches is switched. 54 200807849 The clock is determined by detecting a substantially zero sense voltage level on the switch. 8. The controller of claim 72, wherein the at least one sense signal input comprises one of a signal for sensing a change in current with one of the first windings of the transformer. 81. The controller of claim 72, wherein the controller is configured to control the switch in response to the sensed signal based on a periodic reference. 82. The control (4) of claim 72, wherein the controller is configured to control the switch to switch the direct current to a frequency substantially synchronized with a resonant frequency of one of the continuous forward converters And a clock that is synchronized on the scalar and synchronized with one of the resonant frequency periods of the operation. 83. The controller of claim 72, wherein the sensed signal comprises a component of a total chopping, wherein the controller is configured to control the switch in response to the chopping to suppress the total of the DC output Libo. 84. A single-chip integrated circuit comprising a controller defined in the πth scope of the patent application. 85. A resonant discontinuous forward converter comprising a controller as defined in claim 72 of the scope of the patent application. 2. The resonant discontinuous forward converter of claim 85, further comprising a capacitor associated with the first winding of the transformer, and wherein the resonant device substantially comes from the capacitor A combination of magnetization induction coils of one of the first windings of the transformer. 87. A total power supply comprising: 55 200807849 a total power supply input; a resonant discontinuous forward converter as defined in claim 85; for generating a high DC from the total power supply input a voltage 5 circuit 'to provide a DC input to the resonant discontinuous forward converter; and a DC output coupled to the DC output of the resonant discontinuous forward converter for supplying from the total power supply Provide a lower DC voltage output. 10 88. A forward power converter comprising: an input; a transformer having a primary and a primary winding; configured to exchange power from the input through a power switch of the primary winding; 15 coupled to one of the secondary winding outputs; and a control system having a sensing input and configured to control one of the switches to switch the clock in response to the sensing input A sense # is tuned to the power output from the forward converter; and wherein the sense input is coupled to receive the sensed signal from one of the primary ends of the forward converter. 89. The forward power converter of claim 88, wherein the sensing signal comprises a voltage sensing signal. 90. The forward power converter of claim 88, wherein the sensing 56 200807849 signal comprises a current sensing signal. 91. The forward power converter of claim 88, wherein the control system is configured to regulate an output current of the power converter. • Forward power converters as claimed in Section 88 of the patent, wherein the control system is configured to regulate an output current power converter. 3. A control system for a forward-to-power converter, the power converter comprising: '° an input; a transformer having a primary and primary winding; assembling to switch from the input through the primary winding a power switch coupled to one of the secondary winding outputs; the control system having a sense input to receive the sensed signal from one of the primary ends of the forward converter; and wherein the control system is configured to control One of the switches switches the clock' to adjust the power output from the forward converter in response to the sense signal. 57