WO2021225577A1 - Circuit de mise en forme de tension avec diodes de différents temps de récupération - Google Patents

Circuit de mise en forme de tension avec diodes de différents temps de récupération Download PDF

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Publication number
WO2021225577A1
WO2021225577A1 PCT/US2020/031342 US2020031342W WO2021225577A1 WO 2021225577 A1 WO2021225577 A1 WO 2021225577A1 US 2020031342 W US2020031342 W US 2020031342W WO 2021225577 A1 WO2021225577 A1 WO 2021225577A1
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WO
WIPO (PCT)
Prior art keywords
diode
voltage
shaping circuit
coupled
power switch
Prior art date
Application number
PCT/US2020/031342
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English (en)
Inventor
Arthur B. Odell
Original Assignee
Power Integrations, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Power Integrations, Inc. filed Critical Power Integrations, Inc.
Priority to PCT/US2020/031342 priority Critical patent/WO2021225577A1/fr
Publication of WO2021225577A1 publication Critical patent/WO2021225577A1/fr

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H02M1/34—Snubber circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
    • H02M3/33523—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H02M1/34—Snubber circuits
    • H02M1/348—Passive dissipative snubbers

Definitions

  • the present invention relates generally to power converters, and more specifically to voltage shaping circuits for an energy transfer element of a power converter.
  • Switched mode power converters are commonly used due to their high efficiency, small size and low weight to power many of today’s electronics.
  • Conventional wall sockets provide a high voltage alternating current.
  • ac high voltage alternating current
  • dc direct current
  • the switched mode power converter controller usually provides output regulation by sensing one or more signals representative of one or more output quantities and controlling the output in a closed loop.
  • a switch is utilized to provide the desired output by varying the duty cycle (typically the ratio of the on time of the switch to the total switching period), varying the switching frequency, or varying the number of pulses per unit time of the switch in a switched mode power converter.
  • the duty cycle typically the ratio of the on time of the switch to the total switching period
  • the switching frequency typically the switching frequency
  • the number of pulses per unit time of the switch in a switched mode power converter typically the ratio of the on time of the switch to the total switching period
  • Power converters may include a voltage shaping circuit coupled across a primary winding of the energy transfer element to prevent damage to the switch.
  • the voltage shaping circuit may include passive and/or active components.
  • a passive component may store or maintain energy in the form of a voltage or current.
  • An active component may produce energy in the form of a voltage or a current.
  • FIG. 1 is a diagram illustrating an example power converter with a voltage shaping circuit, in accordance with an embodiment of the present disclosure.
  • FIG. 2 is a timing diagram illustrating example waveforms of various signals in FIG. 1, in accordance with an embodiment of the present disclosure.
  • Voltage shaping circuits may be used to prevent damage to components of a power converter, such as a power switch.
  • a voltage shaping circuit may be referred as a clamp circuit or a snubber circuit in which the voltage level or the rate of change of the voltage at a node is reduced or decreased.
  • Voltage shaping circuits may be coupled across a primary winding of an energy transfer element or the power switch of the power converter and may limit the amount of voltage across the primary winding when the power switch of the power converter is OFF.
  • a large voltage spike may occur at a node between the energy transfer element and the power switch.
  • the voltage spike may be a result of stored energy in a leakage inductance of the energy transfer element of the power converter.
  • the voltage spike should be limited or otherwise controlled to safe levels to limit the voltage stress on the power switch.
  • a voltage shaping circuit coupled to the node between the energy transfer element and the power switch can limit or otherwise control the voltage and potential voltage spikes.
  • Voltage shaping circuits such as a clamp circuit or a snubber circuit, include passive and/or active components, such as resistors, capacitors, and transistors.
  • One example voltage shaping circuit includes a resistor and a capacitor.
  • a resistor-capacitor (RC) voltage shaping circuit generally dissipates a significant amount of energy when limiting voltage spikes at the node of the power switch.
  • a diode with a standard reverse recovery time could be used with an RC voltage shaping circuit to limit the dissipation by allowing some of the energy to return to the energy transfer element as the diode transitions from forward to reverse bias.
  • the reverse recovery time refers to the time it takes for a diode to stop conducting when the diode is reverse biased.
  • a diode with a “standard” or “slow” reverse recovery time typically has a recovery time greater than or equal to 1 microseconds (ps).
  • the addition of the “slow” or “standard” diode to the RC voltage shaping circuit may cause additional ringing of the voltage at the node of the power switch.
  • the diode itself could get too hot by being forced into reverse recovery events multiple times due to the excessive ringing.
  • Embodiments in accordance with the teachings of the present disclosure include a voltage shaping circuit with a “slow” diode used in conjunction with a “fast” or an “ultra-fast” diode. “Fast” diodes have reverse recovery times substantially equal to 70-100 nanoseconds (ns) while “ultra-fast” diodes have reverse recover times substantially equal to 30-50 ns.
  • the voltage shaping circuit may be coupled across a winding of an energy transfer element of a power converter. In other words, the voltage shaping circuit may be coupled to a node of a power transistor and to one end of the winding of an energy transfer element.
  • the voltage shaping circuit may include a first resistor, a second resistor, a capacitor, a first diode, and a second diode.
  • the first diode is a “slow” or “general” recovery diode while the second diode is a “fast” or “ultra-fast” recovery diode.
  • the first diode allows at least some of the leakage energy stored in the capacitor to return to the energy transfer element due to its slow reverse recovery time.
  • the second diode is coupled across the second resistor and shorts the second resistor when the second diode is conducting and clamps voltage spikes at the node of the power switch. In other words, the second diode reduces dissipation across the second resistor.
  • the voltage shaping circuit may reduce dissipation and dampens ringing compared to typical RC voltage shaping circuits. The reduced dissipation and damping may lower electromagnetic interference (EMI) of the power converter.
  • EMI electromagnetic interference
  • FIG. 1 shows a diagram illustrating an example power converter 100 with a voltage shaping circuit 104, in accordance with the teachings of the present disclosure.
  • the power converter 100 is controlled by a first controller 120 and a second controller 122 to transfer energy from an input to an output of the power converter 100.
  • the illustrated example of the power converter 100 includes an energy transfer element 106, a primary winding 108 of the energy transfer element 106, a secondary winding 110 of the energy transfer element 106, a power switch SI 112, an input return 111, a voltage shaping circuit 104, an output rectifier DO 114, an output capacitor CO 116, an output return 117, a second controller 122, a first controller 120, and a communication link 130.
  • the voltage shaping circuit 104 is shown in FIG. 1 as including a capacitance Cl 144, a first diode D1 140, a second diode D2 142, first resistor R1 146, and second resistor R2 148.
  • the first diode D1 140 is a “slow” or “general” recovery diode while the second diode D2 142 is a “fast” or “ultra-fast” recovery diode relative to the “slow” or “general” recovery diode.
  • FIG. 1 further illustrates is an uncoupled inductor LLK 152 in dashed lines, which may represent the leakage inductance associated with the energy transfer element 106 or a discrete inductor.
  • a capacitance Cpi 154 is shown to represent all the capacitance that couples to the power switch SI 112 and may include natural capacitance internal to the energy transfer element 106, the natural internal capacitance of power switch SI 112 and/or discrete capacitors. Also shown in FIG.
  • ⁇ 1 are an input voltage VIN 102, an output voltage Vo 115, an output current Io 119, a feedback signal FB 124, a request signal REQ 128, a current sense signal ISNS 134, a switch current ID 136, a primary drive signal DR 132, a power switch voltage VD 138, a primary voltage VP, a leakage voltage VL, and a shaping circuit current ISB 150.
  • the power converter 100 is shown as having a flyback topology. Further, the input of power converter 100 is galvanically isolated from the output of power converter 100, such that input return 111 is galvanically isolated from output return 117. Since the input and output of power converter 100 are galvanically isolated, there is no direct current (dc) path across the isolation barrier of energy transfer element T1 106, or between primary winding 108 and secondary winding 110, or between input return 111 and output return 117. It is appreciated that other known topologies and configurations of power converters may also benefit from the teachings of the present disclosure. Further, the example shown illustrates a first controller 120 referenced to the input return 111 and a second controller 122 referenced to the output return 117. However, it should be appreciated that a single controller could also be used, such as an input referenced controller that receives a feedback signal.
  • the power converter 100 provides output power to a load 118 from an unregulated input VIN 102.
  • the input VIN 102 is a rectified and filtered ac line voltage.
  • the input voltage VIN 102 is a dc input voltage.
  • the input VIN 102 is coupled to the energy transfer element 106.
  • the energy transfer element 106 may be a coupled inductor, transformer, or an inductor.
  • the example energy transfer element 106 is shown as including two windings, a primary winding 108 and secondary winding 110. However, the energy transfer element 106 may have more than two windings.
  • the uncoupled inductance LLK 152 may be between the power switch SI 112 and the primary winding 108.
  • the uncoupled inductance LLK 152 may represent the leakage inductance associated with the energy transfer element 106 or a discrete inductor.
  • the voltage across the uncoupled inductance LLK 152 may be denoted as the leakage voltage VL.
  • the voltage across the primary winding 108 is illustrated as the primary voltage VP with the positive polarity at the dot end of the primary winding 108.
  • the primary winding 108 of the energy transfer element is further coupled to the power switch SI 112 and the power switch SI 112 is further coupled to input return 111.
  • the voltage at the drain of the power switched SI 112 is denoted as power switch voltage VD 138, which is also the voltage across the parasitic capacitance Cpi 154.
  • Secondary winding 110 is coupled to the output rectifier DO 114, which is exemplified in FIG. 1 as a transistor used as a synchronous rectifier.
  • the output rectifier DO 114 may be a diode.
  • Output capacitor CO 116 is shown as being coupled to the output rectifier DO 114 and the output return 117.
  • the power converter 100 further includes circuitry to regulate the output, which in one example may be the output voltage Vo 115, output current Io 119, or a combination of the two.
  • a feedback signal UFB 124 representative of the output of the power converter 100 is provided to the second controller 122.
  • the second controller 122 is coupled to receive the feedback signal FB 124, representative of the output of the power converter 100 and outputs the secondary drive signal SR 126 and the request signal REQ 128.
  • the secondary drive signal SR 126 is received by the output rectifier DO 114 and controls the turn on and turn off of the output rectifier DO 114.
  • the request signal REQ 128 is representative of a request to turn on the primary switch SI 112.
  • the request signal REQ 128 may include request events that are generated in response to the feedback signal FB 124.
  • the request signal REQ 128 may include request events that are generated in response to a comparison of the feedback signal FB 124 to a target value.
  • the request signal REQ 128 may be a rectangular pulse waveform that pulses to a logic high value and quickly returns to a logic low value.
  • the logic high pulses may be referred to as request events.
  • the request signal REQ 128 may be representative of the received feedback signal FB 124.
  • the first controller 120 is coupled to receive the request signal REQ 128 through a communication link 130, shown as a dashed line, and outputs the primary drive signal DR 132.
  • the first controller 120 provides the primary drive signal DR 132 to the power switch SI 112 to control various switching parameters of the power switch SI 112 to control the transfer of energy from the input of the power converter 100 to the output of the power converter 100 through the energy transfer element 106. Examples of such parameters include switching frequency (or switching period), duty cycle, on-time and off-times, or varying the number of pulses per unit time of the power switch SI 112.
  • the power switch SI 112 may be controlled such that it has a fixed switching frequency or a variable switching frequency. In one example of variable switching frequency control, the switching frequency may be reduced for light-load or no-load conditions.
  • the first controller 120 is also shown as receiving the current sense signal ISNS 134, which is representative of the switch current ID 136. In one example, the first controller 120 outputs the primary drive signal DR 132 to turn off the power switch SI 112 when the switch current ID 136 reaches a current limit.
  • the second controller 122 and the first controller 120 may communicate via the communication link 130.
  • the second controller 122 is coupled to the secondary side of the power converter 100 and is referenced to the output return 117 while the first controller 120 is coupled to the primary side of the power converter 100 and is referenced to the input return 111.
  • the first controller 120 and the second controller 122 are galvanically isolated from one another and the communication link 130 provides galvanic isolation using an inductive coupling, such as a transformer or a coupled inductor, an optocoupler, a capacitive coupling, or other device that maintains the galvanic isolation.
  • the second controller 122 is not galvanically isolated from the first controller 120.
  • the first controller 120 and second controller 122 may be formed as part of an integrated circuit that is manufactured as either a hybrid or monolithic integrated circuit.
  • the power switch SI 112 may also be integrated in a single integrated circuit package with the first controller 120 and the second controller 122.
  • first controller 120 and second controller 122 may be formed as separate integrated circuits.
  • the power switch SI 112 may also be integrated in the same integrated circuit as the first controller 120 or could be formed on its own integrated circuit.
  • both the first controller 120, the second controller 122 and the power switch SI 112 need not be included in a single package and may be implemented in separate controller packages or a combination of combined/separate packages.
  • the power converter 100 could utilize a single controller to turn on and turn off the power switch SI 112.
  • the power switch SI 112 may be a transistor such as a metal-oxide- semiconductor field-effect transistor (MOSFET), a bipolar junction transistor (BJT), a silicon carbide (SiC) based transistor, a gallium nitride (GaN) based transistor, or an insulated-gate bipolar transistor (IGBT). Further, the power switch SI 112 may be comprise several transistors arranged in a cascode configuration, such as a high-voltage GaN based transistor and a low-voltage Si based transistor.
  • MOSFET metal-oxide- semiconductor field-effect transistor
  • BJT bipolar junction transistor
  • SiC silicon carbide
  • GaN gallium nitride
  • IGBT insulated-gate bipolar transistor
  • the voltage shaping circuit 104 may also be referred to as a clamp circuit or a snubber circuit.
  • the voltage shaping circuit 104 may reduce the voltage level and/or reduce the rate of change of the power switch voltage VD 138, which is at a node of the power switch SI 112.
  • the voltage shaping circuit 104 is configured to limit a magnitude and a rate of change of the power switch voltage VD 138 at the drain of the power switch SI 112.
  • the voltage shaping circuit 104 is shown as including a first diode D1 140 coupled the energy transfer element T1 106 and the power switch SI 112.
  • the first diode D1 140 is characterized as a slow or general recovery diode.
  • the first diode D1 140 is further coupled to a second diode D2 142 and a second resistor R2 148.
  • the second diode D2 142 may be characterized as a fast or ultra-fast recovery diode. As shown, the second diode D2 142 is coupled across the resistor R2 148 and in operation shorts the resistor R2 148 when the diode D2 is conducting.
  • Capacitance Cl 144 and the first resistor R1 146 are coupled to the energy transfer element T1 106, the second diode D2 142, and the resistor R2 148.
  • the voltage shaping circuit 104 limits a clamp voltage across the power switch SI 112.
  • the voltage shaping circuit 104 may dampen ringing of the power switch voltage VD 138, which can also reduce EMI.
  • the capacitance Cl 144 stores energy from the primary winding 108 and the uncoupled inductance LLK 152 when the power switch SI 112 turns off.
  • First diode D1 140 has slow/general recovery characteristics, which allow at least some of the energy stored in capacitance Cl 144 to be returned to the energy transfer element T1 106 during the reverse recovery time of the first diode D1 140.
  • the first diode D1 140 could cause additional ringing of the power switch voltage VD 138 and the temperature of the first diode D1 140 could reach undesirable levels due to multiple reverse recovery events caused by the excessive ringing, which may lead to increased EMI.
  • the second resistor R2 148 may be used to dampen ringing of the power switch voltage VD 138 and may also prevent the temperature of the first diode D1 140 from reaching undesirable levels, which may also reduce EMI. However, the temperature of the second resistor R2 may cause excessive dissipation when capacitance Cl 144 is being charged and/or the temperature of the second resistor R2 may rise to undesirable levels. As such, in one example, the second diode D2 142 is coupled across the second resistor R2 148 to short the second resistor R2 148 and reduce the dissipation from the second resistor R2 148 when capacitance Cl 144 is being charged.
  • FIG. 2 shows a timing diagram 200 of example waveforms of the primary drive signal DR 132, the power switch voltage VD 138, the switch current ID 136, and the shaping circuit current ISB 150, which correspond with similarly named and numbered elements as shown in FIG. 1.
  • the primary drive signal DR 134 transitions to a logic high value and the power switch SI 112 transitions from an OFF state to an ON state.
  • the switch current ID 136 would begin to increase from a zero or non-zero value, depending if the power converter 100 is operating in discontinuous conduction mode (DCM) or continuous conduction mode (CCM).
  • the rate that the switch current ID 136 increases is partially determined by the input voltage VIN 102 and the inductance of the primary winding 108.
  • the switch current ID 136 increases until the current limit is reached at time ti 272, which will cause the first controller 120 to output the primary drive signal DR 134 to turn OFF the power switch SI 112.
  • the primary drive signal DR 132 transitions to a logic low value and the power switch SI 112 transitions from the ON state to the OFF state.
  • the power switch voltage VD 138 and shaping circuit current ISB 150 are substantially equal to zero.
  • the shaping circuit current ISB 150 is configured to flow into the voltage shaping circuit 104 through the first diode D1 140 and through the second diode D2 142 to charge the capacitor Cl 144.
  • the thick solid line 255 illustrates the example power switch voltage VD 138 of the voltage shaping circuit 104 of FIG. 1
  • the thick dotted line 256 represents the power switch voltage VD 138 if the voltage shaping circuit 104 did not include the second diode D2 142 and did not include the second resistor R2 148 (e.g., the voltage shaping circuit 104 includes capacitance Cl 144, first resistor R1 146, and first diode D1 140)
  • the thin solid line 257 represents the power switch voltage VD 138 for an example of the voltage shaping circuit 104 that does not include the second diode D2 142 (e.g.
  • the voltage shaping circuit 104 includes capacitance Cl 144, first resistor R1 146, second resistor R2 148, and first diode D1 140).
  • the thick solid line 259 illustrates the example shaping circuit current ISB 150 of the voltage shaping circuit 104 of FIG. 1 while the thick dotted line 258 represents the shaping circuit current ISB 150 if the voltage shaping circuit did not include the second diode D2 142 and did not include the second resistor R2 148 (e.g., the voltage shaping circuit 104 includes capacitance Cl 144, first resistor R1 146, and first diode D1 140).
  • the thick solid line 255 illustrates that the power switch voltage VD 138 of the voltage shaping circuit 104 increases to a value substantially equal to the sum of the input voltage VIN 102, the reflected output voltage VOR 266, and a first pedestal voltage VPED 264 responsive to the voltage shaping circuit 104 at time ti 272.
  • the magnitude of thick solid line 259 representative of the shaping circuit current ISB 150 of the voltage shaping circuit 104 increases at time ti 272 and then begins to decrease.
  • the thick solid line 255 remains at the sum of the input voltage VIN 102, the reflected output voltage VOR 266, and pedestal voltage VPED 264 until time t2274 when the thick solid line 259 representative of the shaping circuit current ISB 150 reaches substantially zero.
  • the time it takes for the thick solid line 259 representative of the shaping circuit current ISB 150 of the voltage shaping circuit 104 to reach zero is substantially a function of the inductance of the primary winding 108, the inductance of the uncoupled inductor 152, and the pedestal voltage VPED 264.
  • the thick solid line 259 illustrates the shaping circuit current ISB 150 of the voltage shaping circuit 104 is positive or greater than zero, indicating that the capacitor Cl 144 is being charged.
  • the shaping circuit current ISB 150 is flowing through first diode D1 140 and second diode D2 142 to the capacitor Cl 144 and first resistor R1 146.
  • the voltage shaping circuit that does not include the second diode D2 142 (e.g . the voltage shaping circuit includes capacitance Cl 144, first resistor R1 146, second resistor R2 148, and first diode D1 140), between times ti 272 and t2 274, the shaping circuit current ISB 150 is flowing through first diode D1 140 and second resistor R2 148 to the capacitor Cl 144 and first resistor R1 146.
  • the second resistor R2 148 can dampen the oscillations of the switch voltage VD 138.
  • the second resistor R2 148 also introduces dissipation for the voltage shaping circuit which can be mitigated with the second diode D2 142 shorting the second resistor R2 148.
  • the thick solid line 259 illustrates the shaping circuit current ISB 150 of the voltage shaping circuit 104 decreasing below zero and then returning to substantially zero. This is representative of the reverse recovery time of the first diode D1 140 and the shaping circuit current ISB 150 is flowing from the capacitor Cl 144 and first resistor R1 146 through second resistor R2 148 and diode D1 140 while the diode D1 140 is in reverse recovery.
  • the thick solid line 255 illustrates the power switch voltage VD 138 of the voltage shaping circuit 104 decreases substantially without ringing to substantially the sum of the input voltage VIN 102 and the reflected output voltage VOR 266.
  • the thick dashed line 256 illustrates that the switch voltage VD 138 would be clamped initially to substantially the sum of the input voltage VIN 102, the reflected output voltage VOR 266, and the pedestal voltage VPED 264 until the shaping circuit current ISB 150 reaches zero at time t2274, but then oscillate around the sum of the input voltage VIN 102 and the reflected output voltage VOR 266 if the voltage shaping circuit did not include the second diode D2 142 and the second resistor R2 148. The oscillation could cause the first diode D1 142 to experience multiple reverse recovery events and may increase the thermal dissipation of the first diode D1 142.
  • the thin solid line 257 illustrates that the power switch voltage VD 138 would increase to the sum of the input voltage VIN 102, the reflected output voltage VOR 266, and a second alternate pedestal voltage VPED’ 265 responsive to the voltage shaping circuit 104 at time ti 272 and then decrease towards around the sum of the input voltage VIN 102 and the reflected output voltage VOR 266 until time t2274, and then oscillate around the sum of the input voltage VIN 102 and the reflected output voltage VOR 266 after time t2274 as shown if the voltage shaping circuit 104 did not include the second diode D2 142.
  • the value for the second alternate pedestal voltage VPED’ 265 is greater than the first pedestal voltage VPED 264 due in part to the second resistor R2 148.
  • the greater of the alternate pedestal voltage VPED’ 265 can correspond to greater dissipation than the example of the voltage shaping circuit 104 shown in FIG. 1 (thick solid line).
  • the ringing of the power switch voltage VD 138 as illustrated with the thin solid line 257 around the sum of the input voltage VIN 102 and the reflected output voltage VOR 266 after time t2274 is a dampened oscillation due to the second resistor R2 148 as compared to the thick dotted line 256.
  • the thick dotted line 258 illustrates the shaping circuit current ISB 150 could oscillate around zero and could eventually settle if the voltage shaping circuit did not include the second diode D2 142 and did not include the second resistor R2 148.
  • the primary drive signal DR 132 transitions to a logic high value to turn on the power switch SI 112 and the power switch voltage VD 138 falls to substantially zero.
  • Example 1 A voltage shaping circuit, comprising: a first diode coupled to one end of an energy transfer element; a first resistor coupled to an other end of the energy transfer element; a capacitor coupled to the first resistor and to the other end of the energy transfer element; a second diode coupled between the first diode and the capacitor, and between the first diode and the first resistor; and a second resistor coupled between the first diode and the capacitor, and between the first diode and the first resistor.
  • Example 2 The voltage shaping circuit of example 1 , wherein the first diode comprises a general recovery diode, and wherein the second diode comprises a fast recovery diode relative to the general recovery diode.
  • Example 3 The voltage shaping circuit of example 1 or 2, wherein the one end of an energy transfer element is coupled to a first node of a power switch, wherein the voltage shaping circuit is configured to limit a magnitude and a rate of change of a switch voltage at the first node of the power switch.
  • Example 4 The voltage shaping circuit of any one of examples 1 to 3, wherein the energy transfer element comprises a first winding and a second winding, wherein the one end of the energy transfer element is a first node of the first winding coupled to the first diode and to the first node of the power switch, wherein the other end of the energy transfer element is a second node of the first winding coupled to first resistor and to the capacitor, and wherein the second winding is coupled to an output of the power converter.
  • Example 5 The voltage shaping circuit of any one of examples 1 to 4, wherein the energy transfer element includes a leakage inductance between the first winding and the first node of the power switch, and wherein the power switch includes a parasitic capacitance coupled to the power switch.
  • Example 6 The voltage shaping circuit of any one of examples 1 to 5, wherein in response to a transition from an ON state to an OFF state of the power switch, a shaping circuit current is configured to flow into the voltage shaping circuit through the first diode and through the second diode to charge the capacitor.
  • Example 7 The voltage shaping circuit of any one of examples 1 to 6, wherein after the transition from the ON state to the OFF state of the power switch, the switch voltage at the first node of the power switch is configured to remain at a clamp voltage until the shaping circuit current flowing into voltage shaping circuit and charging the capacitor through the first diode and through the second diode falls to zero.
  • Example 8 The voltage shaping circuit of any one of examples 1 to 7, wherein after the shaping circuit current falls to zero, the switch voltage is configured to decrease substantially without ringing to substantially a sum of the power converter input voltage and the reflected voltage across the first winding.
  • Example 9 The voltage shaping circuit of any one of examples 1 to 8, wherein the shaping circuit current is configured to flow from the capacitor through the second resistor and through the first diode while the first diode is in reverse recovery after the shaping circuit current falls to zero, wherein the shaping circuit current is configured to decrease below zero and then return to substantially zero while the first diode is in reverse recovery.
  • Example 11 A power converter, comprising: an energy transfer element including a first winding and a second winding, wherein the first winding has a second node coupled to an input of the power converter and the second winding is coupled to an output of the power converter; a power switch having a first node coupled to a first node of the first winding; a controller coupled to the power switch, wherein the controller is configured to generate a drive signal to control switching of the power switch in response to the power converter output to control a transfer of energy from the input of the power converter to the output of the power converter; and a voltage shaping circuit coupled to the first winding and the power switch, wherein the voltage shaping circuit includes: a first diode coupled to the first node of the first winding; a first resistor coupled to the second node of the first winding; a capacitor coupled to the first resistor and to the second node of the first winding; a second diode coupled between the first diode and the capacitor, and between the first diode and the first resistor
  • Example 12 The power converter of example 11, wherein the first diode comprises a general recovery diode, and wherein the second diode comprises a fast recovery diode relative to the general recovery diode.
  • Example 13 The power converter of example 11 or 12, wherein the voltage shaping circuit is configured to limit a magnitude and a rate of change of a switch voltage at the first node of the power switch.
  • Example 14 The power converter of any one of examples 11 to 13, wherein the energy transfer element includes a leakage inductance between first node of the first winding and the first node of the power switch, and wherein the power switch includes a parasitic capacitance coupled to the power switch.
  • Example 15 The power converter of any one of examples 11 to 14, wherein in response to a transition from an ON state to an OFF state of the power switch, a shaping circuit current is configured to flow into the voltage shaping circuit through the first diode and through the second diode to charge the capacitor.
  • Example 16 The power converter of any one of examples 11 to 15, wherein after the transition from the ON state to the OFF state of the power switch, the switch voltage at the first node of the power switch is configured to remain at a clamp voltage until the shaping circuit current flowing into voltage shaping circuit and charging the capacitor through the first diode and through the second diode falls to zero.
  • Example 18 The power converter of any one of examples 11 to 17, wherein the shaping circuit current is configured to flow from the capacitor through the second resistor and through the first diode while the first diode is in reverse recovery after the shaping circuit current falls to zero, wherein the shaping circuit current is configured to decrease below zero and then return to substantially zero while the first diode is in reverse recovery.
  • Example 19 The power converter of any one of examples 11 to 17, wherein the switch voltage is configured to decrease to substantially zero in response to a transition of the power switch from the OFF state to the ON state.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

Un circuit de mise en forme de tension comprend une première diode couplée à une extrémité d'un élément de transfert d'énergie. Une première résistance est couplée à une autre extrémité de l'élément de transfert d'énergie. Un condensateur est couplé à la première résistance et à l'autre extrémité de l'élément de transfert d'énergie. Une seconde diode est couplée entre la première diode et le condensateur, et entre la première diode et la première résistance. Une seconde résistance est couplée entre la première diode et le condensateur, et entre la première diode et la première résistance.
PCT/US2020/031342 2020-05-04 2020-05-04 Circuit de mise en forme de tension avec diodes de différents temps de récupération WO2021225577A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5827216A (ja) * 1981-08-10 1983-02-17 Matsushita Electric Ind Co Ltd スイツチングレギユレ−タ
US5986905A (en) * 1996-10-30 1999-11-16 Pi Electronics (H.K.) Limited Voltage clamp
JP2005094946A (ja) * 2003-09-18 2005-04-07 Matsushita Electric Ind Co Ltd スイッチング電源装置
CN109950299A (zh) * 2019-04-16 2019-06-28 成都方舟微电子有限公司 一种功率集成二极管芯片结构及其制作方法
CN209434869U (zh) * 2018-12-29 2019-09-24 深圳市金锐显数码科技有限公司 一种漏感尖峰电压吸收装置及开关电源

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5827216A (ja) * 1981-08-10 1983-02-17 Matsushita Electric Ind Co Ltd スイツチングレギユレ−タ
US5986905A (en) * 1996-10-30 1999-11-16 Pi Electronics (H.K.) Limited Voltage clamp
JP2005094946A (ja) * 2003-09-18 2005-04-07 Matsushita Electric Ind Co Ltd スイッチング電源装置
CN209434869U (zh) * 2018-12-29 2019-09-24 深圳市金锐显数码科技有限公司 一种漏感尖峰电压吸收装置及开关电源
CN109950299A (zh) * 2019-04-16 2019-06-28 成都方舟微电子有限公司 一种功率集成二极管芯片结构及其制作方法

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