WO2012155325A1 - Dc/dc power converter with wide input voltage range - Google Patents

Dc/dc power converter with wide input voltage range Download PDF

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Publication number
WO2012155325A1
WO2012155325A1 PCT/CN2011/074081 CN2011074081W WO2012155325A1 WO 2012155325 A1 WO2012155325 A1 WO 2012155325A1 CN 2011074081 W CN2011074081 W CN 2011074081W WO 2012155325 A1 WO2012155325 A1 WO 2012155325A1
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WO
WIPO (PCT)
Prior art keywords
node
input voltage
transformer
primary side
converter
Prior art date
Application number
PCT/CN2011/074081
Other languages
French (fr)
Inventor
Shijia YANG
Xiaodong Zhan
Jiong Huang
Original Assignee
Intersil Americas 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 Intersil Americas Inc. filed Critical Intersil Americas Inc.
Priority to PCT/CN2011/074081 priority Critical patent/WO2012155325A1/en
Publication of WO2012155325A1 publication Critical patent/WO2012155325A1/en

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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
    • H02M1/10—Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from ac or dc
    • 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
    • H02M3/01—Resonant DC/DC converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0016—Control circuits providing compensation of output voltage deviations using feedforward of disturbance parameters
    • H02M1/0022—Control circuits providing compensation of output voltage deviations using feedforward of disturbance parameters the disturbance parameters being input voltage fluctuations
    • 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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Definitions

  • the present invention relates to DC/DC voltage converter, and more particularly, to DC/DC voltage converter operating over a wide input voltage range.
  • a buck derived DC/DC converter usually runs in a large duty cycle with a low input voltage and has a small duty cycle for high input voltages.
  • the duty cycle at high input voltages is significantly reduced leading to a significant efficiency reduction.
  • a customer will have to use several narrow input voltage range power modules for different voltage ranges. Typically, 48 volt telecom bricks cover only 36 volts to 75 volts of input voltage range. One or two other modules are required to cover a 9 volt to 36 volt input range. In order to simplify inventory management, customers desire to use one module to cover 9 volts to 75 volts of input voltage range. Thus, there is a need for a high efficiency solution for a wide input voltage range DC/DC power conversion that limits the costs associated with the implementation.
  • the present invention in one aspect thereof comprises a DC/DC voltage converter includes a resonant reset forward converter for generating a regulated output voltage responsive to an input voltage.
  • the resonant reset forward converter includes a transformer having a primary side having a plurality of portions and a secondary side. A plurality of switches, each associated one of the portions of the primary side of the transformer, activate the associated portions of the primary side of the transformer responsive to a plurality of primary side transformer control signals.
  • Control logic generates the primary side transformer control signals responsive to a determination of the input voltage range.
  • FIG. 1 is a block diagram of the manner for providing a wide input voltage range to a DC/DC power converter according to the present disclosure
  • Fig. 2 is a schematic diagram of a DC/DC converter having a wide input voltage range
  • Fig. 3 illustrates the control logic for controlling the input switches of the DC/DC voltage converter
  • Fig. 4 illustrates the lock out circuit associated with the control logic of Fig. 1;
  • Fig. 5 is a flow diagram describing the operation of the circuitry of Fig. 2;
  • Fig. 6 is a schematic diagram of an alternative embodiment of a DC/DC converter having a wide input voltage range.
  • FIG. 1 there is illustrated a block diagram of the DC/DC converter 104 having a wide input voltage range.
  • the input voltage V IN is applied at node 102 to the DC/DC voltage converter 104.
  • the input voltage V IN is also applied to control logic 106 which is used for controlling switching circuitry 108 that is associated with the DC/DC voltage converter 104.
  • the control logic 106 determines the input voltage range of the input voltage V IN and uses that for generating control signals to the associated switching circuitry 108.
  • the switching circuitry 108 activates portions of the primary side of a transformer within the DC/DC voltage converter 104 responsive to the control signals provided by the control logic 106.
  • the particular portions of the transformer that are activated within the DC/DC voltage converter 104 are determined based upon the voltage range detected by the control logic 106 as will be more fully described herein below.
  • the DC/DC voltage converter 104 provides the output voltage V OUT responsive to the input voltage V IN and the activated portions of the associated primary side transformer.
  • the circuit of Fig. 1 is adapted to a wide range of input voltages V IN by using multiple transformer primary windings within the DC/DC voltage converter 104 and primary MOSFET switches within the switching circuitry 108 within a resonant reset forward converter.
  • the input voltage sense circuitry within the control logic 106 enables the corresponding MOSFET switches to run the transformer within the DC/DC voltage converter 104 at an optimized turns ratio. This maximizes the power efficiency of the circuit.
  • the resonant capacitor on the secondary side of the transformer takes advantage of the constant output voltage which guarantees the reset of the transformer in different primary configurations. This enables the replacement of multiple narrow input voltage power modules used within previous applications with a single module as described herein.
  • the input voltage V IN 202 is provided to an input voltage node 204.
  • the input voltage V IN may range from 9 volts to 75 volts.
  • An input capacitance 206 is connected between node 204 and ground.
  • the resonant reset forward converter 208 includes a transformer 210 including a primary side 212 that is broken into four separate portions. While the present discussion has described the primary side 212 of the transformer 210 being broken into four different voltage ranges, the use of other breakdowns of voltage ranges of different numbers may also be provided.
  • a first portion 212a of the primary side of transformer 210 is connected between node 204 and node 214.
  • a second portion 212b is connected between node 214 and node 216.
  • a third portion 212c is connected between node 216 and node 218, and a fourth portion of the primary side of transformer 210 is connected between node 218 and node 220.
  • Each of nodes 214, 216, 218 and 220, respectively, are connected to ground by associated switches 222 through 228, respectively.
  • Switch 222 is connected between node 214 and ground.
  • a resonant capacitor 219 is connected in parallel with switch 222 between node 214 and ground.
  • Switch 224 is connected between node 223 and ground.
  • a diode 225 had the cathode connected to node 223 and its anode connected to node 216. A diode 225 blocks negative current within the circuit. A capacitor 227 connects across switch 224 between node 223 and ground to activate the resonant capacitor. Switch 226 is connected between node 229 and ground. A diode 231 has its cathode connected to node 229 and its anode connected to node 218. A diode 231 blocks negative current within the circuit. A capacitor 233 is connected between node 229 and ground across the switch 226 to activate a resonant capacitor. Switch 228 is connected between node 235 and ground.
  • a diode 237 has its cathode connected to node 235 and its anode connected to node 220 to block negative current within the circuit.
  • a resonant capacitor 239 is connected in parallel with switch 228 between node 235 and ground.
  • switches 224-228 are connected to receive associated control signals from the control logic which will be more fully discussed herein below.
  • switches may comprise P-channel transistors.
  • Diodes 241 are connected in parallel across the terminals of each of switches 224-228.
  • the secondary side 230 of the transformer 210 is connected between node 232 and node 234.
  • An inductor 236 is connected between node 232 and the output voltage node 238.
  • a diode 240 has its cathode connected to node 232 and its anode connected to node 242.
  • Diode 244 has its cathode connected to node 234 and its anode connected to node 242.
  • a capacitor 246 is connected in parallel with diode 244 between node 234 and node 242.
  • a capacitor 248 is connected between node 238 and the ground node 242.
  • the resonant reset forward converter 208 uses the switches 222 through 228 and the transformer primary windings 212 for different ranges of input voltages.
  • the input voltage 202 can range from 9 volts to 75 volts in the example of Fig. 1. However, as discussed previously, other voltage ranges and divisions of the primary winding may also be utilized.
  • the input voltage is divided into four intervals for different switches and portions of the primary winding 212 according to the present disclosure.
  • switch 222 When the input voltage is between 9 volts and 18 volts, switch 222 is turned on and switches 224, 226 and 228 are turned off. This causes the primary winding portion 212a of the primary side of transformer 210 to be active.
  • the number of windings associated with the primary side transformer 212a is PI while the number of turns associated with the secondary side 230 of transformer 210 is SI .
  • the transformer turns ratio When primary side portion 212a is active, the transformer turns ratio will be Pl/Sl .
  • the ratio of the maximum to the minimum duty cycle for the circuit will be 2 to 1 (18 to 9).
  • switch 224 When the input voltage V IN is between 18 volts and 36 volts, switch 224 is turned on while switches 222, 226 and 228 are turned off. This causes portion 212a and 212b of transformer 210 to be active. Transformer portion 212b has a number of windings associated with it indicated by P2. The turns ratio for transformer 210 when gate 224 is turned on will be (PI + P2)/S1 in this voltage range. The ratio of maximum to minimum duty cycle will be 2 to 1 (36 to 18).
  • switch 226 When the input voltage V IN 202 is between 36 volts and 57 volts, switch 226 is turned on while switches 222, 224 and 228 are turned off. This causes portions 212a, 212b and 212c of the primary side of transformer 210 to be active. The number of turns associated with portion 212c of the primary side of transformer 210 is indicated by P3. Thus, the turns ratio for the transformer 210 will be (P1+P2+P3)/S1 in this voltage range. The ratio of maximum to minimum duty cycle of the transformer will be 1.583 to 1 (57 to 36). [0022] Finally, when the input voltage is between 57 volts and 75 volts, switch 228 is turned on while switches 222, 224 and 226 are turned off.
  • the transformer 210 turns ratio will be equal to (P1+P2+P3+P4)/S1 in this voltage range.
  • the ratio of maximum to minimum duty cycle of the transformer is 1.316 to 1 (75 to 57).
  • the control logic 106 of Fig. 3 comprises an input voltage sensing circuit.
  • the input voltage V IN is applied at a plurality of nodes 302, 304, 306 and 308 associated with each of the voltage ranges associated with the different parts of transformer 212.
  • the input voltage sensing circuitry is a dual channel driver with enable function which is active high.
  • Comparators 310, 312, 314 and 316 detect the input voltage intervals applied at each of nodes 302 through 308, respectively.
  • a number of resistor dividers associated with comparators 310 through 316 monitor the input voltage V IN applied at nodes 302 through 308, respectively.
  • the resistor divider associated with comparator 310 includes a resistor 318 connected between node 302 and node 320. Resistor 322 is connected between node 320 and ground. The non-inverting input of comparator 310 is connected to monitor the input voltage V IN at node 320. The reference voltage V REF is applied at node 324 through a resistor 326 between node 324 and 328. A capacitor 330 is connected between node 328 and ground. Node 328 is associated with the inverting input of comparator 310.
  • the resistor divider is a resistor 318 connected between node 302 and node 320. Resistor 322 is connected between node 320 and ground. The non-inverting input of comparator 310 is connected to monitor the input voltage V IN at node 320. The reference voltage V REF is applied at node 324 through a resistor 326 between node 324 and 328. A capacitor 330 is connected between node 328 and ground. Node 328 is associated with the invert
  • the resistor divider associated with comparator 314 includes resistor 346 connected between node 306 and node 348 and resistor 350 connected between node 348 and ground.
  • the comparator 314 has its non-inverting input connected to monitor the input voltage V IN at node 348.
  • the reference voltage V REF is applied at node 352 through resistor 354 connected between node 352 and node 356.
  • a capacitor 358 is connected between node 356 and ground.
  • the inverting input of comparator 314 is connected to node 356.
  • the resistor divider associated with comparator 3 12 includes resistor 332 between node 304 and node 334 and resistor 336 between node 334 and ground.
  • the non-inverting input of comparator 3 12 is connected to node 334 to monitor the input voltage V IN -
  • the reference voltage V REF is applied at node 338 through a resistor 340 connected between node 338 and node 332.
  • a capacitor 344 is connected between node 342 and ground.
  • the inverting input of comparator 3 12 is connected to node 342.
  • the resistor divider associated with comparator 3 12 includes resistor 332 between node 304 and node 334 and resistor 336 between node 334 and ground.
  • the non-inverting input of comparator 3 12 is connected to node 334 to monitor the input voltage V IN -
  • the reference voltage V REF is applied at node
  • the resistor divider associated with comparator 3 16 includes resistor 360 connected between node 308 and node 362 and resistor 364 connected between node 362 and ground.
  • the non-inverting input of comparator 3 16 is connected to node 362.
  • the reference voltage V REF is applied at node 366 through a resistor 368 connected between node 366 and node 370.
  • Capacitor 372 is connected between node 370 and ground.
  • An inverting input of comparator 3 16 is connected to node 370.
  • a resistor 374 is connected between the output of comparator 3 10 and the non- inverting input at node 320.
  • the output of comparator 3 10 is connected to node 376.
  • a number of diodes 378, 380 and 382 each have their cathodes connected to node 376.
  • the anode of diode 378 is connected to node 384, the anode of diode 380 is connected to node 386 and the anode of diode 382 is connected to node 388.
  • a resistor 390 is connected between node 376 and node 392.
  • An inverter 394 has its input connected to node 392 and its output connected to latch 396.
  • a resistor 398 is connected between node 348 and the output of comparator 3 14 at node 399.
  • a pair of diodes 397 and 395 have their cathodes connected to node 399.
  • the anode of diode 397 is connected to node 386 and the anode of diode 397 is connected to node 386.
  • the anode of diode 395 is connected to node 388.
  • a resistor 393 is connected between node 399 and the input of an inverter 391.
  • the output of inverter 391 is connected to the enable D input of latch 396.
  • a resistor 389 is connected between the output of comparator 3 12 at node 387 and node 334 on the non-inverting input of comparator 3 12.
  • a diode 385 has its cathode connected to node 387 and its anode connected to node 388.
  • Resistor 383 is connected between node 387 and node 381.
  • An inverter 379 has its input connected to node 381 and its output connected to the enable A input of latch 377.
  • a resistor 375 is connected between the output of comparator 3 16 at node 373 and its non-inverting input at node 362.
  • a resistor 371 is connected between node 373 and node 369.
  • An inverter 367 has its input connected to node 369 and its output connected to the enable B input of latch 377.
  • the output of latch 396 provides the gate control signals to switches 222 and 224, respectively.
  • the outputs of latch 377 provide the gate control signals to latches 226 and 228, respectively.
  • Enable signals are provided at the inputs of each of inverters 394, 391, 379 and 367, respectively, as will be more fully described herein below with respect to Fig. 4.
  • ENA and ENB signals at latch 396 and ENA and ENB signals at latch 377 are all inactive low causing switches 222, 224, 226 and 228 to be turned off.
  • the converter will then run in an input OVP (Over Voltage Protection) current.
  • OVP Over Voltage Protection
  • Fig. 4 there is illustrated a back up logic lockout circuit used to make sure that only a single switch of switches 222-228 is working at any particular point in time.
  • the back up logic lockout circuit 402 includes four separate portions that are each associated with one gate of the switches 222 through 228 associated with the DC/DC converter.
  • the circuit is connected to the gate of switch 222 at node 403.
  • Three diodes 410, 412 and 414 have their anodes connected to node 403.
  • the cathode of diode 410 is connected to node 351 to provide the ENBl enable signal.
  • the cathode of diode 412 is connected to node 381 to provide the ENA2 enable signal, and the cathode of diode 412 is connected to node 369 to provide the ENB2 enable signal.
  • a capacitor 416 is connected between node 351 and ground.
  • a capacitor 418 is connected between node 381 and ground and a capacitor 420 is connected between node 369 and ground.
  • the lock out circuit is connected to the gate of transistor 224 at node 404.
  • Three diodes 422, 424 and 426 have their anodes connected to node 404.
  • the anodes of each of diodes 422, 424 and 426 are connected to nodes 392, 381 and 369, respectively, to provide the ENA1, ENA2 and E B2 enable signals.
  • Diode 28 is connected between node 392 and ground.
  • the logic lock out circuit 402 is connected to the gate of switch 326 at node 406.
  • Three diodes 430, 432 and 434 have their anodes connected to node 406.
  • the cathode of diode 420 is connected to node 392 to provide the ENA1 enable signal
  • the cathode of diode 432 is connected to node 351 to provide the E B1 enable signal
  • the cathode of diode 434 is connected to the node 369 to provide the ENB2 enable signal.
  • the logic lock out circuit 402 is connected to the fourth switching transistor at node 408.
  • Diodes 436, 438 and 440 have their anodes connected to node 408 and their cathodes connected to nodes 392, 351 and 381, respectively.
  • the enable signal ENA1 is provided at node 392.
  • the enable signal E B1 is provided at node 351 and the enable signal ENA2 is provided at node 381.
  • Fig. 5 there is illustrated a flow diagram describing the operation of the circuitry of Fig. 2.
  • the input voltage is determined at step 502.
  • a determination is made at step 504 of the particular input voltage range in which the input voltage presently lies.
  • the switch associated with this input voltage range is activated at step 506 to activate a particular portion of the primary side of the transformer.
  • the remaining switches within the circuit are maintained in a deactivated state at step 508.
  • the input voltage is regulated using the active portion of the primary side of the transformer at steps 510. This allows the same circuitry to be used for a wide input voltage range.
  • the input voltage V IN 202 is provided to an input voltage node 204.
  • the input voltage V IN may range from 9 volts to 75 volts.
  • An input capacitance 206 is connected between node 204 and ground.
  • the resonant reset forward converter 208 includes a transformer 210 including a primary side that is broken into four separate portions 602-608 that are each separate transformers that are active based on the input voltage. While the present discussion has described the primary side of the transformer 210 being broken into four different voltage ranges, the use of other breakdowns of voltage ranges of different numbers may also be provided.
  • a first transformer 602 of the primary side of transformer 210 is connected between node 204 and switch 222.
  • a second transformer 604 is connected between node 204 and diode 225.
  • a third transformer 606 is connected between node 204 and diode 23 1 , and a fourth transformer 608 of the primary side of transformer 210 is connected between node 204 and diode 337.
  • Switch 222 is connected between node 214 and ground.
  • a resonant capacitor 219 is connected in parallel with switch 222 between node 214 and ground.
  • Switch 224 is connected between node 223 and ground.
  • a diode 225 had the cathode connected to node 223 and its anode connected to node 216.
  • a diode 225 blocks negative current within the circuit.
  • a capacitor 227 connects across switch 224 between node 223 and ground to activate the resonant capacitor.
  • Switch 226 is connected between node 229 and ground.
  • a diode 23 1 has its cathode connected to node 229 and its anode connected to node 218.
  • a diode 23 1 blocks negative current within the circuit.
  • a capacitor 233 is connected between node 229 and ground across the switch 226 to activate a resonant capacitor.
  • Switch 228 is connected between node 235 and ground.
  • a diode 237 has its cathode connected to node 235 and its anode connected to node 220 to block negative current within the circuit.
  • a resonant capacitor 239 is connected in parallel with switch 228 between node 235 and ground.
  • switches 224-228 are connected to receive associated control signals from the control logic described herein above with respect to Figs. 3 and 4.
  • switches may comprise P-channel transistors.
  • Diodes 241 are connected in parallel across the terminals of each of switches 224-228.
  • the secondary side 230 of the transformer 210 is connected between node 232 and node 234.
  • An inductor 236 is connected between node 232 and the output voltage node 238.
  • a diode 240 has its cathode connected to node 232 and its anode connected to node 242.
  • Diode 244 has its cathode connected to node 234 and its anode connected to node 242.
  • a capacitor 246 is connected in parallel with diode 244 between node 234 and node 242.
  • a capacitor 248 is connected between node 238 and the ground node 242.
  • the resonant reset forward converter 208 uses the switches 222 through 228 and the transformer primary windings 212 for different ranges of input voltages.
  • the input voltage 202 can range from 9 volts to 75 volts in the example of Fig. 1. However, as discussed previously, other voltage ranges and divisions of the primary winding may also be utilized. The input voltage is divided into four intervals for different switches and portions of the primary winding according to the present disclosure.
  • switch 222 When the input voltage is between 9 volts and 18 volts, switch 222 is turned on and switches 224, 226 and 228 are turned off. This causes the transformer 602 of the primary side of transformer 210 to be active.
  • the number of windings associated with the transformer 602 is PI while the number of turns associated with the secondary side 230 of transformer 210 is SI .
  • the transformer turns ratio When primary side transformer 602 is active, the transformer turns ratio will be Pl/Sl .
  • the ratio of the maximum to the minimum duty cycle for the circuit will be 2 to 1 (18 to 9).
  • switch 224 When the input voltage V IN is between 18 volts and 36 volts, switch 224 is turned on while switches 222, 226 and 228 are turned off. This causes transformer 604 of the primary side of transformer 210 to be active. Transformer 604 has a number of windings associated with it indicated by P2. The turns ratio for transformer 210 when gate 224 is turned on will be P2/S1 in this voltage range. The ratio of maximum to minimum duty cycle will be 2 to 1 (36 to 18).
  • switch 226 When the input voltage V IN 202 is between 36 volts and 57 volts, switch 226 is turned on while switches 222, 224 and 228 are turned off. This causes transformer 606 of the primary side of transformer 210 to be active.
  • the number of turns associated with transformer 606 of the primary side of transformer 210 is indicated by P3.
  • the turns ratio for the transformer 210 will be P3/S1 in this voltage range.
  • the ratio of maximum to minimum duty cycle of the transformer will be 1.583 to 1 (57 to 36).
  • switch 228 is turned on while switches 222, 224 and 226 are turned off.
  • This activates transformer 608 of the primary side of transformer 210 whose number of turns is represented by P4.
  • the transformer 210 turns ratio will be equal to P4/S1 in this voltage range.
  • the ratio of maximum to minimum duty cycle of the transformer is 1.316 to 1 (75 to 57).
  • the DC/DC converter PWM duty cycle range (max to min) is significantly narrowed, and the DC/DC converter can run in a relatively larger duty cycle near 50% over the entire input voltage range of the converter.
  • the transformer 210 efficiency is higher, and the RMS current in both the primary and secondary side circuitry is lower leading to lower conduction losses and overall high power conversion efficiency.
  • the concept may be applied to a fly-back topology.
  • the duty cycle of the circuit should be around 50 percent.
  • an input of 40 volts to 450 volts will convert to a 12 volt output.
  • the circuit could also be implemented using two primary windings as illustrated in Fig. 7.
  • Fig. 7 illustrates a schematic diagram of an alternative embodiment using the fly-back topology.
  • the input voltage V IN 702 is provided at an input voltage node 704.
  • the input voltage V IN may range from 40 volts to 450 volts.
  • An input capacitor 706 is connected between node 704 and ground.
  • Resonant reset forward converter 708 includes a transformer 710 including a primary side that is broken into two separate portions 712a and 712b. While the following discussion describes the primary side of the transformer 710 being broken into two different voltage ranges, the use of other numbers of portions for the voltage ranges may also be provided.
  • a first transformer portion 712a is connected between node 704 and node 714.
  • a second portion 712b is connected between node 714 and node 716.
  • Node 714 is connected to switch 722.
  • Switch 722 is connected between node 714 and ground.
  • a resonant capacitor 719 is connected in parallel with switch 722 between node 714 and ground.
  • the diode 725 has its anode connected to node 716 and its cathode connected to node 723.
  • Switch 724 is connected between node 723 and ground.
  • the diode 725 blocks negative current within the circuit.
  • a capacitor 727 connects across switch 724 between node 723 and ground to activate the resonant capacitor.
  • Each of the switches 722 and 724 are connected to receive associated control signals from the control logic to activate different portions of the primary side of transformer 710.
  • the switches may comprise P channel transistors.
  • a diode 741 is also connected in parallel with each of capacitors 219 and 227, respectively.
  • the secondary side 730 of transformer 710 is connected between node 732 and node 734.
  • a diode 736 has its anode connected to node 734 and its cathode connected to node 738.
  • a capacitor 740 is connected between node 732 and node 738.
  • a resistor 740 is connected to node 738 and node 732.
  • Node 732 comprises the ground node.
  • the duty cycle for the circuit can be derived as:
  • Vd equals the forward voltage drop of the secondary diode 736.
  • switch 722 is activated and switch 724 is turned off. This activates the primary winding portion 712a of transformer 710.
  • the transformer turns ratio will be equal to P1/S 1(40/13).
  • the ratio of maximum to minimum duty cycle will be 19 to 8 according to the above equation.
  • switch 724 When the input voltage VIN is between 150 volts and 450 volts switch 724 is activated while switch 722 is turned off. Winding portions PI and P2 are both active within transformer 710.
  • the transformer turns ratio is (P1+P2)/S 1(150/13). The ratio of maximum to minimum duty cycle will be 2 to 1 according the above equation.
  • FIG. 8 there is illustrated an alternative embodiment of the proposed fly-back converter wherein separate portions of the primary side are used rather than combined portions as described with respect to Fig. 7.
  • the input voltage VIN 702 is provided at an input voltage node 704.
  • the input voltage VIN may range from 40 volts to 450 volts.
  • An input capacitor 706 is connected between node 704 and ground.
  • Resonant reset forward converter 708 includes a transformer 710 including a primary side that is broken into two separate portions 802 and 804. While the following discussion describes the primary side of the transformer 802 being broken into two different voltage ranges, the use of other numbers of portions for the voltage ranges may also be provided.
  • a first transformer portion 802 is connected between node 704 and node 714.
  • Node 714 is connected to switch 722.
  • Switch 722 is connected between node 714 and ground.
  • a resonant capacitor 719 is connected in parallel with switch 722 between node 714 and ground.
  • a diode 725 has its anode connected to node 716 and its cathode connected to node 723.
  • Switch 724 is connected between node 723 and ground. The diode 725 blocks negative current within the circuit.
  • a capacitor 727 connects across switch 724 between node 723 and ground to activate the resonant capacitor.
  • Each of the switches 722 and 724 are connected to receive associated control signals from the control logic to activate different portions of the primary side of transformer 710.
  • switches may comprise P channel transistors.
  • a diode 741 is also connected in parallel with each of capacitors 219 and 227, respectively.
  • the secondary side 730 of transformer 710 is connected between node 732 and node 734.
  • a diode 736 has its anode connected to node 734 and its cathode connected to node 738.
  • a capacitor 740 is connected between node 732 and node 738.
  • a resistor 740 is connected to node 738 and node 732. Node 732 comprises the ground node.
  • the fly-back converter of Fig. 8 will operate in a similar manner as that described with respect to Fig. 7.
  • switch 822 is active while switch 724 is turned off.
  • the active portion of transformer 710 will be portion 802.
  • the transformer turns ratio will be Pl/S 1(40/13) and the ratio of maximum to minimum duty cycle will be 19 to 8 according to the above equation.
  • switch 724 When the input voltage is between 150 volts and 450 volts switch 724 is active and switch 722 is turned off. This will cause portion 804 of transformer 710 to be active.
  • the transformer turns ratio will be P2/S2(150/13) and the radio of maximum to minimum duty cycle will be 2 to 1 according to the above equation.
  • the primary transformer includes multiple winds to separate the input voltage into several intervals. This will provide a high efficiency solution for wide input voltage range applications.
  • the design allows the replacement of several narrow input voltage power solutions with a single wide input voltage solution which will simplify the circuitry and decrease component costs.

Abstract

A DC/DC power converter with a wide input voltage range includes a resonant reset forward converter (208) for generating a regulated output voltage in response to an input voltage (202). The resonant reset forward converter (208) includes a transformer (210). The transformer (210) has a primary side (212) with a plurality of portions (212a, 212b, 212c, 212d) and a secondary side (230). A plurality of switches (222, 224, 226, 228), each associated with one of the portions (212a, 212b, 212c, 212d) of the primary side (212) of the transformer (210), activate the associated portions (212a, 212b, 212c, 212d) of the primary side (212) of the transformer (210) in response to a plurality of primary side transformer control signals. The converter further includes a control logic (106) which generates the primary side transformer control signals in response to the determination of the input voltage range.

Description

DC/DC POWER CONVERTER WITH WIDE INPUT VOLTAGE RANGE
TECHNICAL FIELD
[0001] The present invention relates to DC/DC voltage converter, and more particularly, to DC/DC voltage converter operating over a wide input voltage range.
BACKGROUND
[0002] Low cost isolated power supplies having multiple outputs are common in many applications such as automotive, security monitoring, telecom, medical instruments, etc. For these applications, multiple output rails are needed for integrated circuits with different operating voltages on the same printed circuit board. Usually, the voltage regulation of these outputs is not tight and the current level is not high. Isolation between the converter input and output is necessary for safety considerations and ground separations.
[0003] When a wide range of input voltages is applied to the input of a DC/DC voltage converter, it is difficult to maintain a high efficiency over the entire input range. A buck derived DC/DC converter usually runs in a large duty cycle with a low input voltage and has a small duty cycle for high input voltages. When the input voltage range is too wide, the duty cycle at high input voltages is significantly reduced leading to a significant efficiency reduction. Within existing solutions, in order to maintain efficiencies high, a customer will have to use several narrow input voltage range power modules for different voltage ranges. Typically, 48 volt telecom bricks cover only 36 volts to 75 volts of input voltage range. One or two other modules are required to cover a 9 volt to 36 volt input range. In order to simplify inventory management, customers desire to use one module to cover 9 volts to 75 volts of input voltage range. Thus, there is a need for a high efficiency solution for a wide input voltage range DC/DC power conversion that limits the costs associated with the implementation.
SUMMARY OF THE INVENTION
[0004] The present invention, as disclosed and described herein, in one aspect thereof comprises a DC/DC voltage converter includes a resonant reset forward converter for generating a regulated output voltage responsive to an input voltage. The resonant reset forward converter includes a transformer having a primary side having a plurality of portions and a secondary side. A plurality of switches, each associated one of the portions of the primary side of the transformer, activate the associated portions of the primary side of the transformer responsive to a plurality of primary side transformer control signals. Control logic generates the primary side transformer control signals responsive to a determination of the input voltage range.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] For a more complete understanding, reference is now made to the following description taken in conjunction with the accompanying Drawings in which: [0006] Fig. 1 is a block diagram of the manner for providing a wide input voltage range to a DC/DC power converter according to the present disclosure;
[0007] Fig. 2 is a schematic diagram of a DC/DC converter having a wide input voltage range;
[0008] Fig. 3 illustrates the control logic for controlling the input switches of the DC/DC voltage converter;
[0009] Fig. 4 illustrates the lock out circuit associated with the control logic of Fig. 1;
[0010] Fig. 5 is a flow diagram describing the operation of the circuitry of Fig. 2; and
[0011] Fig. 6 is a schematic diagram of an alternative embodiment of a DC/DC converter having a wide input voltage range. DETAILED DESCRIPTION
[0012] Referring now to the drawings, wherein like reference numbers are used herein to designate like elements throughout, the various views and embodiments of a DC/DC power converter with wide input voltage range are illustrated and described, and other possible embodiments are described. The figures are not necessarily drawn to scale, and in some instances the drawings have been exaggerated and/or simplified in places for illustrative purposes only. One of ordinary skill in the art will appreciate the many possible applications and variations based on the following examples of possible embodiments.
[0013] Referring now to the drawings, and more particularly to Fig. 1 , there is illustrated a block diagram of the DC/DC converter 104 having a wide input voltage range. The input voltage VIN is applied at node 102 to the DC/DC voltage converter 104. The input voltage VIN is also applied to control logic 106 which is used for controlling switching circuitry 108 that is associated with the DC/DC voltage converter 104. The control logic 106 determines the input voltage range of the input voltage VIN and uses that for generating control signals to the associated switching circuitry 108. The switching circuitry 108 activates portions of the primary side of a transformer within the DC/DC voltage converter 104 responsive to the control signals provided by the control logic 106. The particular portions of the transformer that are activated within the DC/DC voltage converter 104 are determined based upon the voltage range detected by the control logic 106 as will be more fully described herein below. The DC/DC voltage converter 104 provides the output voltage VOUT responsive to the input voltage VIN and the activated portions of the associated primary side transformer.
[0014] The circuit of Fig. 1 is adapted to a wide range of input voltages VIN by using multiple transformer primary windings within the DC/DC voltage converter 104 and primary MOSFET switches within the switching circuitry 108 within a resonant reset forward converter. The input voltage sense circuitry within the control logic 106 enables the corresponding MOSFET switches to run the transformer within the DC/DC voltage converter 104 at an optimized turns ratio. This maximizes the power efficiency of the circuit. The resonant capacitor on the secondary side of the transformer takes advantage of the constant output voltage which guarantees the reset of the transformer in different primary configurations. This enables the replacement of multiple narrow input voltage power modules used within previous applications with a single module as described herein.
[0015] Referring now to Fig. 2, there is provided a schematic diagram of the resonant reset forward converter and associated switching circuitry. The input voltage VIN 202 is provided to an input voltage node 204. The input voltage VIN may range from 9 volts to 75 volts. An input capacitance 206 is connected between node 204 and ground. The resonant reset forward converter 208 includes a transformer 210 including a primary side 212 that is broken into four separate portions. While the present discussion has described the primary side 212 of the transformer 210 being broken into four different voltage ranges, the use of other breakdowns of voltage ranges of different numbers may also be provided.
[0016] A first portion 212a of the primary side of transformer 210 is connected between node 204 and node 214. A second portion 212b is connected between node 214 and node 216. A third portion 212c is connected between node 216 and node 218, and a fourth portion of the primary side of transformer 210 is connected between node 218 and node 220. Each of nodes 214, 216, 218 and 220, respectively, are connected to ground by associated switches 222 through 228, respectively. Switch 222 is connected between node 214 and ground. A resonant capacitor 219 is connected in parallel with switch 222 between node 214 and ground. Switch 224 is connected between node 223 and ground. A diode 225 had the cathode connected to node 223 and its anode connected to node 216. A diode 225 blocks negative current within the circuit. A capacitor 227 connects across switch 224 between node 223 and ground to activate the resonant capacitor. Switch 226 is connected between node 229 and ground. A diode 231 has its cathode connected to node 229 and its anode connected to node 218. A diode 231 blocks negative current within the circuit. A capacitor 233 is connected between node 229 and ground across the switch 226 to activate a resonant capacitor. Switch 228 is connected between node 235 and ground. A diode 237 has its cathode connected to node 235 and its anode connected to node 220 to block negative current within the circuit. A resonant capacitor 239 is connected in parallel with switch 228 between node 235 and ground. Each of switches 224-228 are connected to receive associated control signals from the control logic which will be more fully discussed herein below. In one embodiment, switches may comprise P-channel transistors. Diodes 241 are connected in parallel across the terminals of each of switches 224-228.
[0017] The secondary side 230 of the transformer 210 is connected between node 232 and node 234. An inductor 236 is connected between node 232 and the output voltage node 238. A diode 240 has its cathode connected to node 232 and its anode connected to node 242. Diode 244 has its cathode connected to node 234 and its anode connected to node 242. A capacitor 246 is connected in parallel with diode 244 between node 234 and node 242. A capacitor 248 is connected between node 238 and the ground node 242. [0018] In order to maintain the efficiency of the DC/DC voltage converter at a high level over a wide range of input voltages, the resonant reset forward converter 208 uses the switches 222 through 228 and the transformer primary windings 212 for different ranges of input voltages. The input voltage 202 can range from 9 volts to 75 volts in the example of Fig. 1. However, as discussed previously, other voltage ranges and divisions of the primary winding may also be utilized. The input voltage is divided into four intervals for different switches and portions of the primary winding 212 according to the present disclosure.
[0019] When the input voltage is between 9 volts and 18 volts, switch 222 is turned on and switches 224, 226 and 228 are turned off. This causes the primary winding portion 212a of the primary side of transformer 210 to be active. The number of windings associated with the primary side transformer 212a is PI while the number of turns associated with the secondary side 230 of transformer 210 is SI . When primary side portion 212a is active, the transformer turns ratio will be Pl/Sl . The ratio of the maximum to the minimum duty cycle for the circuit will be 2 to 1 (18 to 9).
[0020] When the input voltage VIN is between 18 volts and 36 volts, switch 224 is turned on while switches 222, 226 and 228 are turned off. This causes portion 212a and 212b of transformer 210 to be active. Transformer portion 212b has a number of windings associated with it indicated by P2. The turns ratio for transformer 210 when gate 224 is turned on will be (PI + P2)/S1 in this voltage range. The ratio of maximum to minimum duty cycle will be 2 to 1 (36 to 18).
[0021] When the input voltage VIN 202 is between 36 volts and 57 volts, switch 226 is turned on while switches 222, 224 and 228 are turned off. This causes portions 212a, 212b and 212c of the primary side of transformer 210 to be active. The number of turns associated with portion 212c of the primary side of transformer 210 is indicated by P3. Thus, the turns ratio for the transformer 210 will be (P1+P2+P3)/S1 in this voltage range. The ratio of maximum to minimum duty cycle of the transformer will be 1.583 to 1 (57 to 36). [0022] Finally, when the input voltage is between 57 volts and 75 volts, switch 228 is turned on while switches 222, 224 and 226 are turned off. This activates all portions of the primary side of transformer 210 including portion 212d whose number of turns is represented by P4. Thus, the transformer 210 turns ratio will be equal to (P1+P2+P3+P4)/S1 in this voltage range. The ratio of maximum to minimum duty cycle of the transformer is 1.316 to 1 (75 to 57). [0023] Using this adaptive circuit configuration, the DC/DC converter PWM duty cycle range (max to min) is significantly narrowed, and the DC/DC converter can run in a relatively larger duty cycle near 50% over the entire input voltage range of the converter. With the large duty cycle, the transformer 210 efficiency is higher, and the RMS current in both the primary 212 and secondary 232 side circuitry is lower leading to lower conduction losses and overall high power conversion efficiency.
[0024] Referring now to Fig. 3, there is illustrated the control logic 106 for controlling the DC/DC voltage converter of Fig. 2. The control logic 106 of Fig. 3 comprises an input voltage sensing circuit. The input voltage VIN is applied at a plurality of nodes 302, 304, 306 and 308 associated with each of the voltage ranges associated with the different parts of transformer 212. The input voltage sensing circuitry is a dual channel driver with enable function which is active high. Comparators 310, 312, 314 and 316 detect the input voltage intervals applied at each of nodes 302 through 308, respectively. A number of resistor dividers associated with comparators 310 through 316 monitor the input voltage VIN applied at nodes 302 through 308, respectively.
[0025] The resistor divider associated with comparator 310 includes a resistor 318 connected between node 302 and node 320. Resistor 322 is connected between node 320 and ground. The non-inverting input of comparator 310 is connected to monitor the input voltage VIN at node 320. The reference voltage VREF is applied at node 324 through a resistor 326 between node 324 and 328. A capacitor 330 is connected between node 328 and ground. Node 328 is associated with the inverting input of comparator 310. The resistor divider
R2
including resistors 318 and 322 is set according to the equation: x 18v = VREF .
R\ + R2
[0026] The resistor divider associated with comparator 314 includes resistor 346 connected between node 306 and node 348 and resistor 350 connected between node 348 and ground. The comparator 314 has its non-inverting input connected to monitor the input voltage VIN at node 348. The reference voltage VREF is applied at node 352 through resistor 354 connected between node 352 and node 356. A capacitor 358 is connected between node 356 and ground. The inverting input of comparator 314 is connected to node 356. The
R4
resistor divider associated with comparator 314 is set by the equation: ——— x36v = VREF . [0027] The resistor divider associated with comparator 3 12 includes resistor 332 between node 304 and node 334 and resistor 336 between node 334 and ground. The non-inverting input of comparator 3 12 is connected to node 334 to monitor the input voltage VIN- The reference voltage VREF is applied at node 338 through a resistor 340 connected between node 338 and node 332. A capacitor 344 is connected between node 342 and ground. The inverting input of comparator 3 12 is connected to node 342. The resistor divider associated
R6
with comparator 3 12 is set according to the equation: x 57v = REF ■
R5 + R6
[0028] Finally, the resistor divider associated with comparator 3 16 includes resistor 360 connected between node 308 and node 362 and resistor 364 connected between node 362 and ground. The non-inverting input of comparator 3 16 is connected to node 362. The reference voltage VREF is applied at node 366 through a resistor 368 connected between node 366 and node 370. Capacitor 372 is connected between node 370 and ground. An inverting input of comparator 3 16 is connected to node 370. The resistor divider of comparator 3 16 is set by the equation: ——— x 75v = Vnww .
R7 + RS REF [0029] A resistor 374 is connected between the output of comparator 3 10 and the non- inverting input at node 320. The output of comparator 3 10 is connected to node 376. A number of diodes 378, 380 and 382 each have their cathodes connected to node 376. The anode of diode 378 is connected to node 384, the anode of diode 380 is connected to node 386 and the anode of diode 382 is connected to node 388. A resistor 390 is connected between node 376 and node 392. An inverter 394 has its input connected to node 392 and its output connected to latch 396.
[0030] A resistor 398 is connected between node 348 and the output of comparator 3 14 at node 399. A pair of diodes 397 and 395 have their cathodes connected to node 399. The anode of diode 397 is connected to node 386 and the anode of diode 397 is connected to node 386. The anode of diode 395 is connected to node 388. A resistor 393 is connected between node 399 and the input of an inverter 391. The output of inverter 391 is connected to the enable D input of latch 396. [0031] A resistor 389 is connected between the output of comparator 3 12 at node 387 and node 334 on the non-inverting input of comparator 3 12. A diode 385 has its cathode connected to node 387 and its anode connected to node 388. Resistor 383 is connected between node 387 and node 381. An inverter 379 has its input connected to node 381 and its output connected to the enable A input of latch 377.
[0032] A resistor 375 is connected between the output of comparator 3 16 at node 373 and its non-inverting input at node 362. A resistor 371 is connected between node 373 and node 369. An inverter 367 has its input connected to node 369 and its output connected to the enable B input of latch 377. [0033] The output of latch 396 provides the gate control signals to switches 222 and 224, respectively. The outputs of latch 377 provide the gate control signals to latches 226 and 228, respectively. Enable signals are provided at the inputs of each of inverters 394, 391, 379 and 367, respectively, as will be more fully described herein below with respect to Fig. 4.
[0034] When the input voltage VIN is below 18 volts, the output at comparator 3 10 is at a logical "low" level and the enable A input at latch 396 will be at an active "high" level. The logical values at node 384, 386 and 388 will be pulled low by diodes 378, 380 and 382, respectively, which will cause signals ENB at latch 396, and ENA and ENB at latch 377 to a logical inactive "low" level. Thus, switch 222 will have its gate signal gi driven by the PWM signal while switches 224, 226 and 228 remain turned off. [0035] When the input voltage is between 18 volts and 36 volts, the output of comparator 3 14 is at a logical "low" level and the ENB signal at latch 396 will be at an active "high" level. The signal at nodes 386 and 388 will be pulled "low" by diodes 397 and 395, respectively. This will cause the ENA signal at latch 377 and ENB signal at latch 377 to a logical "low" level. Thus, switch 224 will have its gate driven by the PWM signal while switches 222, 226 and 228 remain turned off.
[0036] When the input voltage VIN is between 36 volts and 57 volts, the outputs of comparator 3 10 and comparator 3 14 will be at a logical "high" level, and the ENA signal and ENB signal at latch 396 will be at an inactive "low" level. The output of comparator 3 12 will be "low" and the enable A input at latch 377 will be at an active "high" level. The signal at node 388 will be pulled low by diode 385 which causes the ENB signal at latch 377 to an inactive "low" level. Thus, the gate of switch 226 will be driven by the PWM signal while switches 222, 224 and 228 will be turned off.
[0037] When the input voltage is between 57 volts and 75 volts, the output of comparators 210, 314 and 312 are at a logical "high" level, and the ENA signal and ENB signal at latch 396 and ENA signal at latch 377 will be at an inactive "low" level. The output of comparator 316 is at a logical "low" level, and the ENB signal at latch 377 will be at an active "high" level. The gate of switch 228 will then be driven by the PWM signal and switches 222, 224 and 226 will be turned off. [0038] Finally, when the input voltage is higher than 75 volts, the outputs of comparators 310, 312, 314 and 316 are all at a logical "high" level. ENA and ENB signals at latch 396 and ENA and ENB signals at latch 377 are all inactive low causing switches 222, 224, 226 and 228 to be turned off. The converter will then run in an input OVP (Over Voltage Protection) current. [0039] Referring now to Fig. 4, there is illustrated a back up logic lockout circuit used to make sure that only a single switch of switches 222-228 is working at any particular point in time. The back up logic lockout circuit 402 includes four separate portions that are each associated with one gate of the switches 222 through 228 associated with the DC/DC converter. The circuit is connected to the gate of switch 222 at node 403. Three diodes 410, 412 and 414 have their anodes connected to node 403. The cathode of diode 410 is connected to node 351 to provide the ENBl enable signal. The cathode of diode 412 is connected to node 381 to provide the ENA2 enable signal, and the cathode of diode 412 is connected to node 369 to provide the ENB2 enable signal. A capacitor 416 is connected between node 351 and ground. A capacitor 418 is connected between node 381 and ground and a capacitor 420 is connected between node 369 and ground. When switch 222 is switching, the pulses at the gate of switch 222 will charge the capacitors 416, 418 and 420 up to a logic high level through diodes 410, 412 and 414. This will cause the voltages at each of nodes 351, 381 and 369 to an inactive low level.
[0040] The lock out circuit is connected to the gate of transistor 224 at node 404. Three diodes 422, 424 and 426 have their anodes connected to node 404. The anodes of each of diodes 422, 424 and 426 are connected to nodes 392, 381 and 369, respectively, to provide the ENA1, ENA2 and E B2 enable signals. Diode 28 is connected between node 392 and ground. When switch 224 is switching, the pulses at the gate of switch 224 will charge capacitors 428, 418 and 420 to a logic "high" level through diodes 422, 412 and 414. This will cause nodes 392, 381 and 369 to an inactive "low" level.
[0041] The logic lock out circuit 402 is connected to the gate of switch 326 at node 406. Three diodes 430, 432 and 434 have their anodes connected to node 406. The cathode of diode 420 is connected to node 392 to provide the ENA1 enable signal, the cathode of diode 432 is connected to node 351 to provide the E B1 enable signal and the cathode of diode 434 is connected to the node 369 to provide the ENB2 enable signal. When switch 226 is switching, the pulses at the gate of transistor 226 at node 406 will charge capacitors 428, 416 and 418 to a logic "high" level through diodes 422, 416 and 412. This will cause nodes 392, 351 and 381 to an inactive "low" level.
[0042] Finally, the logic lock out circuit 402 is connected to the fourth switching transistor at node 408. Diodes 436, 438 and 440 have their anodes connected to node 408 and their cathodes connected to nodes 392, 351 and 381, respectively. The enable signal ENA1 is provided at node 392. The enable signal E B1 is provided at node 351 and the enable signal ENA2 is provided at node 381. When switch 228 is switching, the pulses at the gate of switch 228 at node 408 will charge capacitors 428, 416 and 418 to a logic "high" level through diode 436, 438 and 440 which will cause nodes 392, 351 and 381 to an inactive "low" level.
[0043] Referring now to Fig. 5, there is illustrated a flow diagram describing the operation of the circuitry of Fig. 2. Initially, the input voltage is determined at step 502. A determination is made at step 504 of the particular input voltage range in which the input voltage presently lies. Based upon this determination, the switch associated with this input voltage range is activated at step 506 to activate a particular portion of the primary side of the transformer. The remaining switches within the circuit are maintained in a deactivated state at step 508. The input voltage is regulated using the active portion of the primary side of the transformer at steps 510. This allows the same circuitry to be used for a wide input voltage range. [0044] Referring now to Fig. 6, there is provided a schematic diagram of an alternative embodiment of the resonant reset forward converter and associated switching circuitry. The input voltage VIN 202 is provided to an input voltage node 204. The input voltage VIN may range from 9 volts to 75 volts. An input capacitance 206 is connected between node 204 and ground. The resonant reset forward converter 208 includes a transformer 210 including a primary side that is broken into four separate portions 602-608 that are each separate transformers that are active based on the input voltage. While the present discussion has described the primary side of the transformer 210 being broken into four different voltage ranges, the use of other breakdowns of voltage ranges of different numbers may also be provided.
[0045] A first transformer 602 of the primary side of transformer 210 is connected between node 204 and switch 222. A second transformer 604 is connected between node 204 and diode 225. A third transformer 606 is connected between node 204 and diode 23 1 , and a fourth transformer 608 of the primary side of transformer 210 is connected between node 204 and diode 337. Switch 222 is connected between node 214 and ground. A resonant capacitor 219 is connected in parallel with switch 222 between node 214 and ground. Switch 224 is connected between node 223 and ground. A diode 225 had the cathode connected to node 223 and its anode connected to node 216. A diode 225 blocks negative current within the circuit. A capacitor 227 connects across switch 224 between node 223 and ground to activate the resonant capacitor. Switch 226 is connected between node 229 and ground. A diode 23 1 has its cathode connected to node 229 and its anode connected to node 218. A diode 23 1 blocks negative current within the circuit. A capacitor 233 is connected between node 229 and ground across the switch 226 to activate a resonant capacitor. Switch 228 is connected between node 235 and ground. A diode 237 has its cathode connected to node 235 and its anode connected to node 220 to block negative current within the circuit. A resonant capacitor 239 is connected in parallel with switch 228 between node 235 and ground. Each of switches 224-228 are connected to receive associated control signals from the control logic described herein above with respect to Figs. 3 and 4. In one embodiment, switches may comprise P-channel transistors. However, other types of switches and various sizes of switches may be used in either of the embodiments of Figs. 2 and 6. Diodes 241 are connected in parallel across the terminals of each of switches 224-228. [0046] The secondary side 230 of the transformer 210 is connected between node 232 and node 234. An inductor 236 is connected between node 232 and the output voltage node 238. A diode 240 has its cathode connected to node 232 and its anode connected to node 242. Diode 244 has its cathode connected to node 234 and its anode connected to node 242. A capacitor 246 is connected in parallel with diode 244 between node 234 and node 242. A capacitor 248 is connected between node 238 and the ground node 242.
[0047] In order to maintain the efficiency of the DC/DC voltage converter at a high level over a wide range of input voltages, the resonant reset forward converter 208 uses the switches 222 through 228 and the transformer primary windings 212 for different ranges of input voltages. The input voltage 202 can range from 9 volts to 75 volts in the example of Fig. 1. However, as discussed previously, other voltage ranges and divisions of the primary winding may also be utilized. The input voltage is divided into four intervals for different switches and portions of the primary winding according to the present disclosure.
[0048] When the input voltage is between 9 volts and 18 volts, switch 222 is turned on and switches 224, 226 and 228 are turned off. This causes the transformer 602 of the primary side of transformer 210 to be active. The number of windings associated with the transformer 602 is PI while the number of turns associated with the secondary side 230 of transformer 210 is SI . When primary side transformer 602 is active, the transformer turns ratio will be Pl/Sl . The ratio of the maximum to the minimum duty cycle for the circuit will be 2 to 1 (18 to 9).
[0049] When the input voltage VIN is between 18 volts and 36 volts, switch 224 is turned on while switches 222, 226 and 228 are turned off. This causes transformer 604 of the primary side of transformer 210 to be active. Transformer 604 has a number of windings associated with it indicated by P2. The turns ratio for transformer 210 when gate 224 is turned on will be P2/S1 in this voltage range. The ratio of maximum to minimum duty cycle will be 2 to 1 (36 to 18).
[0050] When the input voltage VIN 202 is between 36 volts and 57 volts, switch 226 is turned on while switches 222, 224 and 228 are turned off. This causes transformer 606 of the primary side of transformer 210 to be active. The number of turns associated with transformer 606 of the primary side of transformer 210 is indicated by P3. Thus, the turns ratio for the transformer 210 will be P3/S1 in this voltage range. The ratio of maximum to minimum duty cycle of the transformer will be 1.583 to 1 (57 to 36).
[0051] Finally, when the input voltage is between 57 volts and 75 volts, switch 228 is turned on while switches 222, 224 and 226 are turned off. This activates transformer 608 of the primary side of transformer 210 whose number of turns is represented by P4. Thus, the transformer 210 turns ratio will be equal to P4/S1 in this voltage range. The ratio of maximum to minimum duty cycle of the transformer is 1.316 to 1 (75 to 57).
[0052] Using this adaptive circuit configuration, the DC/DC converter PWM duty cycle range (max to min) is significantly narrowed, and the DC/DC converter can run in a relatively larger duty cycle near 50% over the entire input voltage range of the converter. With the large duty cycle, the transformer 210 efficiency is higher, and the RMS current in both the primary and secondary side circuitry is lower leading to lower conduction losses and overall high power conversion efficiency.
[0053] In yet further embodiments illustrated in Figs. 7 and 8, the concept may be applied to a fly-back topology. In order to increase the overall efficiency, the duty cycle of the circuit should be around 50 percent. For example, an input of 40 volts to 450 volts will convert to a 12 volt output. The circuit could also be implemented using two primary windings as illustrated in Fig. 7. Fig. 7 illustrates a schematic diagram of an alternative embodiment using the fly-back topology. The input voltage VIN 702 is provided at an input voltage node 704. The input voltage VIN may range from 40 volts to 450 volts. An input capacitor 706 is connected between node 704 and ground. Resonant reset forward converter 708 includes a transformer 710 including a primary side that is broken into two separate portions 712a and 712b. While the following discussion describes the primary side of the transformer 710 being broken into two different voltage ranges, the use of other numbers of portions for the voltage ranges may also be provided. A first transformer portion 712a is connected between node 704 and node 714. A second portion 712b is connected between node 714 and node 716. Node 714 is connected to switch 722. Switch 722 is connected between node 714 and ground. A resonant capacitor 719 is connected in parallel with switch 722 between node 714 and ground. The diode 725 has its anode connected to node 716 and its cathode connected to node 723. Switch 724 is connected between node 723 and ground. The diode 725 blocks negative current within the circuit. A capacitor 727 connects across switch 724 between node 723 and ground to activate the resonant capacitor. Each of the switches 722 and 724 are connected to receive associated control signals from the control logic to activate different portions of the primary side of transformer 710. In one embodiment, the switches may comprise P channel transistors. A diode 741 is also connected in parallel with each of capacitors 219 and 227, respectively.
[0054] The secondary side 730 of transformer 710 is connected between node 732 and node 734. A diode 736 has its anode connected to node 734 and its cathode connected to node 738. A capacitor 740 is connected between node 732 and node 738. A resistor 740 is connected to node 738 and node 732. Node 732 comprises the ground node. [0055] The turn ratio of the transformer 710 may be established such that P1 :P2: S 1 = 40: 1 10: 13. The duty cycle for the circuit can be derived as:
Figure imgf000015_0001
where Vd equals the forward voltage drop of the secondary diode 736. When the input voltage is between 30 volts and 150 volts, switch 722 is activated and switch 724 is turned off. This activates the primary winding portion 712a of transformer 710. The transformer turns ratio will be equal to P1/S 1(40/13). The ratio of maximum to minimum duty cycle will be 19 to 8 according to the above equation.
[0056] When the input voltage VIN is between 150 volts and 450 volts switch 724 is activated while switch 722 is turned off. Winding portions PI and P2 are both active within transformer 710. The transformer turns ratio is (P1+P2)/S 1(150/13). The ratio of maximum to minimum duty cycle will be 2 to 1 according the above equation.
[0057] Referring now to Fig. 8, there is illustrated an alternative embodiment of the proposed fly-back converter wherein separate portions of the primary side are used rather than combined portions as described with respect to Fig. 7. The input voltage VIN 702 is provided at an input voltage node 704. The input voltage VIN may range from 40 volts to 450 volts. An input capacitor 706 is connected between node 704 and ground. Resonant reset forward converter 708 includes a transformer 710 including a primary side that is broken into two separate portions 802 and 804. While the following discussion describes the primary side of the transformer 802 being broken into two different voltage ranges, the use of other numbers of portions for the voltage ranges may also be provided. A first transformer portion 802 is connected between node 704 and node 714. A second portion 804 connected between node 714 and node 716. Node 714 is connected to switch 722. Switch 722 is connected between node 714 and ground. A resonant capacitor 719 is connected in parallel with switch 722 between node 714 and ground. A diode 725 has its anode connected to node 716 and its cathode connected to node 723. Switch 724 is connected between node 723 and ground. The diode 725 blocks negative current within the circuit. A capacitor 727 connects across switch 724 between node 723 and ground to activate the resonant capacitor. Each of the switches 722 and 724 are connected to receive associated control signals from the control logic to activate different portions of the primary side of transformer 710. In one embodiment, switches may comprise P channel transistors. A diode 741 is also connected in parallel with each of capacitors 219 and 227, respectively. [0058] The secondary side 730 of transformer 710 is connected between node 732 and node 734. A diode 736 has its anode connected to node 734 and its cathode connected to node 738. A capacitor 740 is connected between node 732 and node 738. A resistor 740 is connected to node 738 and node 732. Node 732 comprises the ground node.
[0059] The fly-back converter of Fig. 8 will operate in a similar manner as that described with respect to Fig. 7. The turns ratio may be established according to P1 :P2:S1=40: 150: 13. When the voltage is between 40 volts and 150 volts, switch 822 is active while switch 724 is turned off. The active portion of transformer 710 will be portion 802. The transformer turns ratio will be Pl/S 1(40/13) and the ratio of maximum to minimum duty cycle will be 19 to 8 according to the above equation. [0060] When the input voltage is between 150 volts and 450 volts switch 724 is active and switch 722 is turned off. This will cause portion 804 of transformer 710 to be active. The transformer turns ratio will be P2/S2(150/13) and the radio of maximum to minimum duty cycle will be 2 to 1 according to the above equation.
[0061] Using the above described circuitries the primary transformer includes multiple winds to separate the input voltage into several intervals. This will provide a high efficiency solution for wide input voltage range applications. The design allows the replacement of several narrow input voltage power solutions with a single wide input voltage solution which will simplify the circuitry and decrease component costs.
[0062] It will be appreciated by those skilled in the art having the benefit of this disclosure that this DC/DC power converter with wide input voltage range provides a single module for providing a regulated voltage over a wide range of inputs. It should be understood that the drawings and detailed description herein are to be regarded in an illustrative rather than a restrictive manner, and are not intended to be limiting to the particular forms and examples disclosed. On the contrary, included are any further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments apparent to those of ordinary skill in the art, without departing from the spirit and scope hereof, as defined by the following claims. Thus, it is intended that the following claims be interpreted to embrace all such further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments.

Claims

WHAT IS CLAIMED IS:
1. A DC/DC voltage converter, comprising:
a resonant reset forward converter for generating a regulated output voltage responsive to an input voltage, the resonant reset forward converter including a transformer having a primary side having a plurality of portions and a secondary side;
a plurality of switches each associated one of the portions of the primary side of the transformer for activating the portions of the primary side of the transformer responsive to a plurality of primary side transformer control signals; and
control logic for generating the primary side transformer control signals responsive to a determination of the input voltage range.
2. The DC/DC voltage converter of Claim 1, wherein responsive to detection of the input voltage in a first range a first portion of the primary side of the transformer is activated and responsive to detection of the input voltage in a second range a second portion of the primary side of the transformer is activated.
3. The DC/DC voltage converter of Claim 1, wherein the control logic further
comprises a plurality of detector circuits each detecting a separate voltage range of the input voltage and generating one of the primary side transformer control signals responsive thereto for activating a selected portion of the plurality of portions of the primary side of the transformer.
4. The DC/DC voltage converter of Claim 1, wherein the control logic further
includes lockout control circuitry for deactivating selected switches of the plurality of switches responsive to detection of the input voltage in a selected input voltage range.
5. The DC/DC voltage converter of Claim 1, wherein the plurality of switches
further comprise switching transistors.
6. A method of generating a regulated output voltage responsive to an input voltage over a wide input voltage range comprising the steps of:
monitoring the input voltage;
determining an input voltage range associated with the input voltage;
activating at least one switch associated with a selected portion of a primary side of a resonant reset forward converter responsive to the input voltage range; deactivating at least one switch associated with the remaining portions of the primary side of the resonant reset forward converter responsive to the input voltage range; and
generating the regulated output voltage using the active portions of the primary side of the transformers responsive to the input voltage.
7. The method of Claim 6, wherein the step of activating further includes the step of generating primary side transformer control signals responsive to a determination of the input voltage range.
PCT/CN2011/074081 2011-05-16 2011-05-16 Dc/dc power converter with wide input voltage range WO2012155325A1 (en)

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GB2535932A (en) * 2013-12-30 2016-08-31 Shenzhen China Star Optoelect Flyback boosted circuit, LED backlight drive circuit and liquid crystal display
WO2015100805A1 (en) * 2013-12-30 2015-07-09 深圳市华星光电技术有限公司 Flyback boosted circuit, led backlight drive circuit and liquid crystal display
GB2535932B (en) * 2013-12-30 2020-06-17 Shenzhen China Star Optoelect Flyback boost circuit, LED backlight driving circuit and liquid crystal device
WO2015195012A1 (en) * 2014-06-18 2015-12-23 Telefonaktiebolaget L M Ericsson (Publ) Switched mode power supply and method of operating a switched mode power supply
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CN105763031A (en) * 2014-12-15 2016-07-13 伊顿制造（格拉斯哥）有限合伙莫尔日分支机构 Automatic voltage regulator with wide input voltage range
CN105763031B (en) * 2014-12-15 2020-06-09 伊顿制造（格拉斯哥）有限合伙莫尔日分支机构 Automatic voltage regulator with wide input voltage range
CN107231090A (en) * 2016-03-23 2017-10-03 施耐德电气工业公司 Switch mode power
CN107437900B (en) * 2016-05-27 2021-12-03 恩智浦有限公司 Resonant power converter with switchable reflected output voltage
US9831787B1 (en) 2016-05-27 2017-11-28 Nxp B.V. Resonant power converter with switchable reflected output voltage
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WO2020104597A1 (en) * 2018-11-22 2020-05-28 Danmarks Tekniske Universitet Isolated dc-dc power converter with adjustable turns ratio
US20210152096A1 (en) * 2019-11-18 2021-05-20 Minmax Technology Co., Ltd. Wide Input Voltage Range Power Converter Circuit in a One-Stage-Two-Switch Configuration
EP3823150A1 (en) * 2019-11-18 2021-05-19 Minmax Technology Co., Ltd. Wide input voltage range power converter circuit in a one-stage-two-switch configuration
US11569749B2 (en) 2019-11-18 2023-01-31 Minmax Technology Co., Ltd. Wide input voltage range power converter circuit in a one-stage- two-switch configuration
CN113315393A (en) * 2021-05-21 2021-08-27 安徽省东科半导体有限公司 Self-adaptive wide-voltage output circuit of switching power supply

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