WO2022175365A1 - Convertisseurs de puissance c.a.-cc et c.c.-c.a. isolés - Google Patents

Convertisseurs de puissance c.a.-cc et c.c.-c.a. isolés Download PDF

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Publication number
WO2022175365A1
WO2022175365A1 PCT/EP2022/053894 EP2022053894W WO2022175365A1 WO 2022175365 A1 WO2022175365 A1 WO 2022175365A1 EP 2022053894 W EP2022053894 W EP 2022053894W WO 2022175365 A1 WO2022175365 A1 WO 2022175365A1
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WIPO (PCT)
Prior art keywords
isolated
input
power converter
bridge
node
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Application number
PCT/EP2022/053894
Other languages
English (en)
Inventor
Bruno Putzeys
Lars Risbo
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Purifi Aps
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Publication date
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Publication of WO2022175365A1 publication Critical patent/WO2022175365A1/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
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/4258—Arrangements for improving power factor of AC input using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage
    • 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
    • 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
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/4233—Arrangements for improving power factor of AC input using a bridge converter comprising active switches
    • 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
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/4241—Arrangements for improving power factor of AC input using a resonant converter
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33584—Bidirectional converters
    • 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 in one aspect to an isolated AC-DC power converter comprising primary side circuitry comprising first and second AC input nodes, con nectable to an AC voltage source, for receipt of an AC input voltage and secondary side circuitry comprising first and second outputs connectable to a converter load.
  • Another aspect of the invention relates to a corresponding bidirectional isolated AC- DC/DC-AC power converter.
  • the present isolated AC-DC power converters may for example function as power supply for electronic equipment that does not need a tightly regulated DC voltage. Audio power amplifiers are an example of such a function or application. In such cases, the traditional approach of cascading a power-factor correction (PFC) front- end with a regulated LLC DC-DC converter is not economic.
  • PFC power-factor correction
  • one objective of the present invention is to provide power factor correction and galvanic isolation using a single converter stage for example merely comprising four actively controlled semiconductor switches.
  • Traditional PFC circuits operate on rectified mains voltage and power losses incurred in an accompanying rectifier bridge can be up to 5% of the power delivered to the converter load.
  • FIG. 1 - FIG. 5 show various types of prior art power converters to further explain and exemplify the background of the invention, wherein:
  • FIG. 1 shows a schematic circuit diagram of a common type of prior art non-isolated PFC constructed around a boost converter
  • FIG. 2 shows a schematic circuit diagram of a prior art LLC converter like a galvani cally isolated DC-DC converter
  • FIG. 3 shows a schematic circuit diagram of prior art LLC converters constructed with full-bridge power stages
  • FIG. 4 shows a schematic circuit diagram of a prior art flyback converter configured as a galvanically isolated PFC
  • FIG. 5 shows a schematic circuit diagram of a prior art bridgeless PFC constructed by two ordinary boost converters with the AC input connected between.
  • the common type of non-isolated PFC according to FIG.1 comprises an AC input 1 from the mains which is rectified using a diode bridge 2.
  • Choke 3, diode 4 and low- side switch 5 form a boost converter whose output voltage is set to be greater than the expected peak of the AC input voltage.
  • switch 5 When switch 5 is on, energy is stored in the choke.
  • switch 5 When switch 5 is off, the choke current flows through the diode 4 to charge the DC link capacitor 7.
  • the control circuit 10 may vary the switching fre quency and duty cycle of the low-side switch 5 to regulate the input current.
  • the lat ter may be sensed between the diode bridge 20 and a primary ground 8.
  • the input current is regulated such that it is substantially proportional with the instantaneous value of the rectified AC voltage 11.
  • the proportionality factor is slowly varied to reg ulate the DC link voltage 6 found on the DC link capacitor 7.
  • the primary ground 8 may not be real ground but simply the most negative voltage in the PFC circuit and is used as
  • FIG. 2 shows a prior art LLC converter, which is a galvanically isolated DC-DC con verter.
  • the prior art LLC converter uses a half or full bridge power stage 14 con nected to a primary winding of a transformer 19 through a capacitor 15.
  • the series inductance 16 is typically not a separate part but is in fact a representation of the leakage inductance of the transformer.
  • the non-ideal transformer 19 is drawn as an equivalent circuit consisting of a fully coupled pair of inductors 17 and 18 with the leakage inductance placed explicitly in series with the primary inductor 17.
  • Prac tical prior art LLC converters therefore have only one magnetic assembly containing inductors 16, 17 and 18 that we simply call the transformer.
  • the power stage is op erated by alternatively turning on high and low side switches 12, 13, respectively. Both switches are turned on for the same length of time and a short blanking delay is introduced between the moment one is turned off and the other is turned on. Switches 12 and 13 inherently contain diodes which can conduct the current during the blanking delay. At times when none of the diodes of the secondary rectifier bridge 20 is turned on, the series capacitor resonates at a resonant frequency f1 de fined by the primary inductance and the leakage inductance together. At times when two of the diodes in the rectifier bridge conduct, the secondary winding 18 is effec tively shorted in AC terms, and consequently so is the primary winding 17. Under these conditions the series capacitor forms a series resonant circuit with the leakage inductance alone, resonating at a second resonant frequency f2.
  • the duty cycle is fixed at 50%. Regulation is achieved by varying the frequency. More power is transmitted if the LLC converter is run near f 1 , and less if the switching frequency of the LLC converter is increased above f1.
  • the output volt age regulation range is not large, so the input voltage range of an LLC converter should not vary too much.
  • the amount of regulation provided by a boost PFC is suf ficient, which is why the LLC converter and the boost PFC are commonly used to gether.
  • FIG. 3 shows LLC converters of the prior art constructed with a full-bridge power stages.
  • the high side switch 12a of the first half bridge 14a and the low side switch 13b of the second half bridge 14b are turned on and off together, as are the low side switch 13a and the high side switch 12b.
  • the first half-bridge switching node 22a is connected to the DC link 6 when the second half-bridge switching node 22b is connected to the primary ground 8.
  • the peak-to-peak voltage applied to the primary winding of the transformer 19 is twice as large as it was in the case of the half-bridge LLC converter of Figure 2.
  • An LLC can also be operated without regulation. In that case the switching frequency is commonly set to be equal to the second resonance frequency f2. This is not a requirement but it provides the best load regulation.
  • the DC output voltage found across output capacitor 21 scales proportionally with the DC link voltage. Because of this property, unregulated LLC converters are sometimes referred to as “DC transformers”.
  • DC transformer to denote an LLC converter that is not actively regulated.
  • FIG. 4 shows a flyback converter adapted as a galvanically isolated PFC.
  • the usual primary DC link capacitor is removed and all energy storage is carried out on the secondary side by output capacitor 21. Control is done more or less like a standard boost PFC. Adding an active clamp switch 22 and capacitor 23 improves the efficiency of the converter.
  • FIG. 5 shows a bridgeless PFC constructed by taking two normal boost converters with the AC input connected between them.
  • a PFC that does not need a rectifier bridge is commonly referred to as “bridgeless PFC” in short.
  • the rectifier bridge at the AC input constitutes a significant power loss mechanism.
  • the most common de sign of bridgeless PFCs adds a second active switch and a second diode.
  • a first aspect of the invention relates to an isolated AC-DC power converter comprising:
  • primary side circuitry comprising first and second AC input nodes connectable to an AC voltage source for receipt of an AC input voltage and secondary side circuitry comprising first and second outputs connectable to a converter load; and wherein the primary side circuitry further comprises:
  • a first half-bridge configured to alternatingly connect a first half-bridge switching node to a DC link voltage, e.g. a DC input voltage ,DC link, and a primary ground node in accordance with a first set of switch control signals
  • a second half-bridge configured to alternatingly connect a second half-bridge switching node to the DC link voltage and a primary ground node in accordance with a second set of switch control signals
  • a transformer comprising a primary side winding connected between the first half bridge switching node and the second half-bridge switching node and a secondary side winding coupled to an input of a secondary side rectification circuit
  • At least one input inductance of the primary side circuitry is electrically connectable, and connected through the AC voltage source under operation, between the first half-bridge switching node and the second half-bridge switching node through the first and second AC input nodes.
  • An optional output capacitor may be connected to an output node of the secondary side rectification circuit to provide a DC output voltage of the isolated AC-DC power converter. The skilled person will understand that this output capacitor is optional but may be helpful to reduce ripple and/or noise on the DC output voltage.
  • the primary side winding of the transformer comprises the at least one input inductance of the primary side circuitry, e.g. because the primary side winding and the at least one in put inductance are a single physically integrated magnetics component.
  • the secondary side circuitry further comprises an inductor connected to one side of the DC blocking capacitor and further connected across the input of the secondary side rectification circuit to provide a resonance frequency of the secondary side circuitry.
  • the at least one inductance of the primary side circuitry and primary side winding of the trans former are physically separate components.
  • the at least one input inductance pref erably comprises: a first input choke connected between the first AC input node and the first half bridge switching node and a second input choke connected between the second AC input node and the second half-bridge switching node.
  • the primary side circuitry further comprises a second capacitor connected between the primary side winding of the transformer and one of the first and second half-bridge switching nodes.
  • the secondary side rectification circuit comprises a full-bridge rectifier comprising at least four indi vidually controllable semiconductor switches.
  • the first half bridge comprises first and second series connected semiconductor switches cou pled between the DC link voltage and primary ground node and with respective con trol terminals coupled to the first set of switch control signals; and the second half-bridge comprises third and fourth series connected semiconductor switches coupled between the DC link voltage (DC link) and primary ground node and with respective control terminals coupled to the second set of switch control sig nals.
  • each of the first and second series connected semiconductor switches comprises a wide bandgap semiconductor such as silicon carbide based switch device; and each of the third and fourth series connected semiconductor switches comprises a wide bandgap semiconductor such as silicon carbide based switch device.
  • the isolated AC-DC power converter comprises a control circuit.
  • the control circuit comprises a power factor correction loop (PFC) configured to regulate average line current, flowing through the first and second AC input nodes, to be substantially sinusoidal and substantially in phase with instantaneous amplitude of the AC input voltage by regulating the first and second sets of switch control signals.
  • PFC power factor correction loop
  • control cir cuit additionally comprises an output voltage regulation loop configured to adjust or control the DC output voltage using the DC link voltage as intermediate variable preferably by adjusting a level of the average line current.
  • a second aspect of the invention relates to a bidirectional isolated AC-DC/ DC-AC power converter comprising an isolated AC-DC power converter according to any of the above-described embodiments of the isolated AC-DC power converter.
  • the iso lated AC-DC/ DC-AC power converter is advantageous because of its ability to pro vide power flow in both directions though the converter from the AC voltage source to the DC output voltage and vice versa.
  • a third aspect of the invention relates to a DC-AC power inverter, such as an iso lated DC-AC power inverter for example an isolated bidirectional AC-DC converter operated to transfer power back from the DC output to the AC input.
  • the DC-AC power inverter preferably comprises: primary side circuitry comprising first and second AC input nodes, connectable to an AC converter load and wherein the primary side circuitry further comprises a first half-bridge configured to alternatingly connect a first half-bridge switching node to a DC link voltage and a primary ground node in accordance with a first set of switch control signals.
  • a second half-bridge is configured to alternatingly connect a second half-bridge switching node to the DC link voltage and a primary ground node in accordance with a second set of switch control signals.
  • the second half-bridge preferably further comprises a first capacitor connected between the DC link voltage and the primary ground node.
  • the DC-AC power inverter comprises a transformer comprising a primary side wind ing connected between the first half-bridge switching node and the second half bridge switching node and a secondary side winding coupled to an input of a sec ondary side synchronous rectification circuit.
  • At least one input inductance of the pri mary side circuitry is electrically connectable, and connected through the AC con verter load under converter operation, between the first half-bridge switching node and the second half-bridge switching node to the DC link voltage and primary ground.
  • a secondary side circuitry may comprise first and second DC output nodes connectable to a DC voltage source such as a rechargeable battery.
  • the primary side circuitry further comprises said secondary side synchronous rectification circuit connected between the secondary side winding and the DC source through the first and DC output nodes.
  • FIG. 6A is a schematic circuit diagram of an isolated AC-DC power converter com prising an integrated magnetics component in accordance with a first embodiment of the invention
  • FIG. 6B is a schematic circuit diagram of the first embodiment of the isolated AC-DC power converter with additional details of the control circuit
  • FIG. 6C illustrates schematically a first test circuit for the first embodiment of the iso lated AC-DC power converter
  • FIG. 6D illustrates schematically a second test circuit for the first embodiment of the isolated AC-DC power converter
  • FIG. 6E illustrates schematically a third test circuit for the first embodiment of the isolated AC-DC power converter
  • FIG. 7 is a schematic circuit diagram of an isolated AC-DC power converter com prising a secondary inductor in accordance with a second embodiment of the inven tion,
  • FIG. 8 is a schematic circuit diagram of an isolated AC-DC power converter wherein an input inductance of the primary side circuitry and a primary side transformer winding are arranged as physically separate components in accordance with a third embodiment of the invention
  • FIG. 9A is a schematic circuit diagram of an isolated AC-DC power converter config ured with bidirectional power transfer capability in accordance with a fourth embodi ment of the invention.
  • FIG. 9B is a schematic circuit diagram of the fourth embodiment of the isolated AC- DC power converter comprising an exemplary embodiment of a controller configured to implement bidirectional power transfer,
  • FIG. 9C is a schematic circuit diagram of an alternative application of the fourth em bodiment of the isolated AC-DC power converter
  • FIG. 10 shows simulated time-domain waveform plots of various operational cur rents flowing in semiconductor switches and transformer windings of the first em bodiment of the isolated AC-DC power converter under a first operating condition as given in FIG. 6C,
  • FIG. 11 shows simulated time-domain waveform plots of various operational volt ages on circuit nodes of the first embodiment of the isolated AC-DC power converter under a first operating condition as given in FIG. 6C
  • FIG. 12 shows simulated time-domain waveform plots of various operational cur rents flowing in semiconductor switches and transformer windings of the first em bodiment of the isolated AC-DC power converter under the first operating condition as given in FIG. 6D
  • FIG. 13 shows simulated time-domain waveform plots of various operational volt ages on circuit nodes of the first embodiment of the isolated AC-DC power converter under the first operating condition given in FIG. 6D;
  • FIG. 14 shows respective simulated time-domain waveform plots of various opera tional currents flowing in semiconductor switches and transformer windings of the first embodiment of the isolated AC-DC power converter under an aggregation, or combination, of the first and second operating conditions as given in FIG. 6E.
  • operation of the present iso lated AC-DC power converter from one perspective may be viewed as superimpos ing operation of a bridgeless boost PFC converter with operation of an LLC con verter or DC transformer utilizing in an advantageous manner the same semicon ductor switches to implement both operations.
  • FIG. 6A is a schematic circuit diagram of an isolated AC-DC power converter 600 comprising an integrated magnetics component in accordance with a first embodi ment of the invention.
  • the isolated AC-DC power converter 600 comprises a trans former 19 comprising a primary side winding comprising first and second half-wind ings 17a, 17b connected between a first half-bridge switching node 22a and a sec ond half-bridge switching node 22b of first and second half-bridges, respectively.
  • the transformer 19 additionally comprises a secondary side winding 18 coupled to an input of a secondary side rectification circuit 20.
  • the other ends of the primary windings 17a and 17b are connected to the AC voltage source 1.
  • an AC voltage source 1 provides an AC input voltage, e.g. mains voltage, to the first and second AC input nodes 2,3 during operation of the power converter 600.
  • the above-mentioned superposition of the respective operations of the bridgeless boost PFC converter and the DC transformer is most easily understood by consider ing two distinct conditions of states of the isolated AC-DC power converter 600 such that only one takes place at a time.
  • the first operating condition comprises a sec ondary load current which substantially is zero so that the secondary rectification bridge 20 never conducts.
  • the isolated AC-DC power converter 600 in response op erates as if no secondary side were present at all. This first operating condition ac cordingly leaves us with a power converter 600 circuit that resembles the bridgeless PFC circuit on Figure 5 discussed above.
  • first and second input inductances which are integrally formed by the first and second half-windings 17a, 17b, operate as a differential input inductance or input choke.
  • the function of this differential choke is analogous to the choke 3 of the boost PFC of FIG. 1 above or analogous to the chokes 3a, 3b of the bridgeless PFC of FIG. 5 above.
  • the use of two input inductances instead of one may be advantageous to suppress or eliminate certain EMI problems, but is not a fundamental feature of the present isolated AC- DC power converter 600, and the applicant’s invention at large.
  • the present isolated AC-DC power converters are fully operational with a single input inductance associ ated with the primary side winding wherein the other one of the first and second half bridge switching nodes is connected directly to the AC input nodes 2, 3 without any input inductance.
  • FIGS. 10 and 11 Various device currents and voltages of an exemplary embodiment of the present isolated AC-DC power converter during the first state or operating condition are schematically illustrated on FIGS. 10 and 11.
  • Inductance of the primary side winding of the transformer 19 comprising the first and second half-windings 17a, 17b coupled in series: 90 pH.
  • Inductance of the secondary side winding 18 of transformer 19 90 pH.
  • Nominal power rating of the isolated AC-DC power converter 600 may be 600W.
  • the second state or operating condition is reached at times where energy stored in the DC link capacitor 7 is transmitted to the secondary side while no power is drawn from the AC source 1.
  • the AC source 1 may be imagined or considered as being replaced by a short circuit such that the isolated AC-DC power converter 600 solely operates as a DC transformer, converting the DC link voltage (DC link voltage) 6 across the input capacitor 7 to the DC output voltage, Vout, across the output capacitor 21.
  • the series capacitor 15 appears on the secondary side circuitry which is a difference with previous examples of prior art DC transformers. The skilled person will understand that this is done to permit operation of the circuit 600 when the duty cycle of the switching waveform deviates from 50%.
  • the operation of the AC-DC power converter 600 is essentially that of a DC trans former.
  • the operation of the isolated AC-DC power converter 600 may be understood by first considering two conditions where only one of the above-mentioned first and second operating conditions take place. For that illustration the inventors have picked a time during the cycle of the AC input voltage where the instantaneous input voltage across input nodes 2, 3 is 75V. Over the time scale covered by the below- appended plots or oscillograms the input voltage may be considered essentially con stant. The output power is 600W.
  • the first and second operating conditions or regimes, in separation thus comprises:
  • FIG. 6C shows a test arrangement simulating the first operating condi tion.
  • the duty cycle needs to be 25%.
  • FIG. 6C comprises arrows to clarify the polarity of the currents given in the graphs of FIG. 10.
  • the RMS current in each of the semi conductor switches 12a and 13b is 5.0A, while the RMS currents in each of the sem iconductor switches 12b and 13a is 7.9A as illustrated by time-domain waveform plots 1001, 1002 and 1003 of FIG. 10.
  • the corresponding RMS currents in the each of the first and second half-windings 17a, 17b of the primary transformer winding is 8.4A.
  • FIG. 11 shows the voltage waveforms associated with the first operating condition, where time-domain waveform plots 1101 , 1102 and 1103 show the respective volt ages across the first and second half-windings 17a, 17b of the primary transformer winding and the total voltage across the latter winding.
  • the isolated AC-DC power converter 600 op erates as a DC transformer wherein a DC link voltage is applied to the DC input/link capacitor 7 and a test load is connected across the output capacitor 21 as schemati cally illustrated by the second test circuit of FIG. 6D.
  • This DC voltage is the same 150V as is produced in the first operating condition.
  • the isolated AC-DC power converter 600 only partly benefits from the resonance frequency provided between series capacitor C res (15) and inductance U (16) by making a shortest part of the switching cycle (the 25%) equal to one-half of the reso nant period of the series capacitor C res (15) and inductance U (16).
  • the resonance frequency provided by the series capacitor C res (15) and inductance U (16) may lie about 100 kHz - for example between 50 kHz and 200 kHz.
  • 25% of the switching cycle may be selected to be equal to 0.5/100kHz.
  • the switching frequency of the isolated AC-DC power con verter 600 is accordingly selected to 50 kHz.
  • the RMS current in each of the semiconductor switches 12a and 13b is 4.4A as illustrated by time-domain waveform plot 1201 of FIG. 12.
  • the RMS current is 3.4A in each of the semiconductor switches 12b and 13a as illustrated by time-domain waveform plot 1202 of FIG. 12.
  • the RMS current is 5.4A in each of the first and second half-windings 17a, 17b as illustrated by time- domain waveform plot 1203 of FIG. 12.
  • Time-domain waveform plots 1301, 1302 and 1303 of FIG. 13 show the respective voltages across the first and second half windings 17a, 17b of the primary transformer winding and the total voltage across the latter winding.
  • the converter load is connected across the output capacitor 21 and the AC input voltage is applied between the free ends of the first and second half-windings 17a, 17b as schematically illustrated by the third test circuit of FIG. 6E.
  • the RMS current is 7.2A in the semiconductor switches 12a and 13b as illustrated by time-domain waveform plot 1401 of FIG. 14.
  • the RMS current in each of the semiconductor switches 12b and 13a is 4.6A as illustrated by time-domain waveform plot 1402 of FIG. 14.
  • the RMS current in each of the first and second half-windings 17a, 17b of the primary transformer winding is 8.6A as illustrated by time-domain waveform plot 1403 of FIG. 14.
  • the present invention provides for a marked im provement in overall system efficiency or marked reduction of power losses of power converters, e.g. as the illustrated isolated AC-DC power converter 600 in ac cordance with one embodiment of the invention.
  • the operating principle of the AC-DC power converter 600 can be summed up by observing that the converter 600 converts the AC input voltage to the DC link volt age by using the primary side winding 17a, 17b as input inductance or input choke.
  • the converter 600 converts the DC link voltage to a galvanically isolated DC output voltage by using the transformer 19 normally in combination with a secondary recti bomb bridge 20 and storage capacitor 21.
  • the series capacitor 15 is preferably ar ranged in the secondary side circuitry of the isolated AC-DC power converter 600, because the primary side winding 17a, 17b of the transformer 19 is operated as a choke and conducts the low-frequency input current when the transformer 19 and input choke or chokes are integrally formed.
  • This low-frequency input current should preferably not be blocked by a series capacitor of the primary side circuitry.
  • the series capacitor 15 is advantageous because whenever the isolated AC- DC power converter 600 is not operating at a duty cycle of 50%, a square wave switching voltage in the secondary side circuitry will suffer an undesired DC shift, or baseline shift, due to a missing DC component.
  • the series capacitor 15 acts to re store the missing DC component.
  • the series capacitor 15 therefore ensures that re gardless of the duty cycle of the switching control or drive signal at the primary side circuitry the peak-to-peak voltage is rectified by the secondary rectifier bridge 20.
  • the capacitance of the series capacitor 15 may for example be selected such that a resonance frequency at, or near to, the switching frequency of the isolated AC-DC power converter 600 is obtained in combination with a leakage inductance 16 of the secondary side winding 18.
  • the secondary side leakage inductance 16 is now depicted as appearing in series with the secondary side transformer winding 18.
  • this is a matter of representation only and has no implica tions on the actual construction of the transformer 19.
  • the iso lated AC-DC power converter 600 operates optimally with a duty cycle around 50% because a square wave at a duty cycle of 50% possesses the largest possible fun damental component which is least impeded by the leakage inductance. This hap pens near the zero crossings of the AC input voltage where maximum energy trans fer from the DC link voltage to the secondary side circuitry takes place.
  • the power converter 600 effectively segues continually be tween functioning primarily as a PFC and primarily as a DC transformer.
  • the fact that power converters in accordance with the present invention combine both func tions does not materially increase a maximum current stress on power devices like the respective semiconductor switches of the first half bridge 14a and the second half bridge 14b.
  • the power converter 600 can for example be controlled like the prior art bridgeless PFCs discussed above.
  • a control circuit 10 or controller of the power converter 600 is preferably configured to provide or implement two nested feedback loops via the first and second sets of switch control signals applied to the respective control terminals of the semiconduc tor switches 12a, 13a of the first half bridge 14a and the semiconductor switches 12b, 13b of the second half bridge 14b, respectively.
  • the first feedback loop may comprise power factor correction (PFC) configured to regulate average line current, flowing through the first and second AC input nodes 2, 3 to be substantially sinusoi dal and substantially in phase with the AC input voltage by regulating the first and second sets of switch control signals.
  • the second feedback loop may comprise an output voltage regulation loop configured to control the DC output voltage Vout, us ing the DC link voltage as intermediate variable, by adjusting a level of the average line current.
  • the second feedback preferably regulates the DC link voltage over a longer time span by adjusting an amplitude of the sinusoidal input current requested from the first feedback loop.
  • the DC transformer operation of the power converter 600 thereafter proceeds automatically, without further intervention from the control circuit
  • At least the semiconductor switches 12a, 13a of the first half bridge 14a and the semiconductor switches 12b, 13b of the second half bridge 14b comprises, or are formed by, wide bandgap FETs, for exam ple based on Silicon Carbide, to allow the PFC functionally of the power converter 600 to operate in continuous conduction mode.
  • This particular feature, or embodi ment, of the present power converters means that the duty cycle and the switching frequency of the power converter 600 may be varied separately or independently.
  • the first feedback loop may be configured to exclusively control or ad just the duty cycle of the switching control signals in order to function.
  • the switching frequency may be controlled separately to exploit the leakage induct ance as much as possible to control the power transfer between primary side and secondary side circuitry of the power converter 600.
  • the switching frequency of the power converter 600 may for example lie between 50 kHz and 5 MHz such as be tween 100 kHz and 2 MHz.
  • the series capacitor 15 was moved to the secondary side in order to allow low-fre quency currents to flow through the primary side winding of the transformer 19, a prerequisite to using it as a boost converter as discussed above in connection with FIG. 6A.
  • a possible disadvantage of this circuit topology of the power converter 600 is the loss of a resonance frequency which would have otherwise permitted better regulation. This disadvantage is eliminated in the isolated AC-DC power converter 700 in accordance with a second embodiment of the invention as illustrated by the schematic circuit diagram on FIG. 7.
  • the isolated AC-DC power converter 700 may be largely similar to the power converter 600 and controlled in a similar manner, but additionally comprises an inductor 23 in the secondary side circuitry which serves to reinstate the resonance frequency on the secondary side.
  • the inductor 23 is prefer ably arranged after, and in series with, the resonant capacitor 15 and in parallel with the input to the secondary rectifier bridge 20.
  • the operation of the isolated AC-DC power converter 700 may be similar to conventional LLC converters and the output voltage regulation can be controlled in a corresponding manner.
  • the skilled person will appreciate that the isolated AC-DC power converter 700 retains one of the sig nificant advantages of the invention, i.e. the dual use of one power stage which comprises the first and second half bridges 14a, 14b.
  • the isolated AC-DC power converter 800 in accordance with a third embodiment of the invention as illustrated by the schematic circuit diagram on FIG. 8 includes at least one separate input inductance or choke on the primary side to allow boost op eration.
  • the isolated AC-DC power converter 800 preferably comprises first and second separate, i.e. physically separate components relative to the transformer 19, input inductances or chokes 3a, 3b in the primary side circuitry as schematically il lustrated.
  • the first input inductance 3a is electrically connected between the first AC input node 2 and the second half-bridge switching node 22b and the second input inductance 3b is electrically connected between the second AC input node 2 and the first half-bridge switching node 22a.
  • the series resonant capacitor 15 is preferably returned to the primary side circuitry as illustrated on FIG. 8.
  • the isolated AC-DC power converter 800 may be controlled in a similar manner to the previously discussed isolated AC-DC power converter 600 of FIG. 6.
  • One pronounced advantage of the isolated AC-DC power converter 800 is that the optimum construction of the first and second input inductances 3a, 3b and that of the transformer 19 may not be the same.
  • the first and second input inductances 3a, 3b may be wound on respective iron powder toroidal cores while the transformer 19 may be a planar design comprising printed circuit board windings for primary side winding or windings and the secondary side winding.
  • the latter embodiment of the isolated AC-DC power converter 800 comprises two or three physically separate inductors, their combined cost, size and power loss may still be less than if one integrated magnetic component or assembly were used to perform all roles.
  • the secondary rectifier bridge 20 or secondary side rectifica tion circuit 20 is illustrated as a diode bridge in the above-outlined embodiments of the present isolated AC-DC power converters, 600, 700, 800.
  • the skilled person will understand that the actual implementations of the secondary side rectification cir cuits 20 may be based on synchronous rectification bridges, i.e. comprising actively controlled semiconductor switches as replacement for the diodes, in order not to waste the improved power efficiency caused by eliminating the primary side rectifier bridge coupled to the AC input voltage.
  • the utilization of synchronous rectification bridges in the secondary side circuitry of the present isolated AC-DC power convert ers, 600, 700, 800 is further advantageous because such synchronous rectification bridges allows reverse operation of the power converters.
  • FIG. 9A One such embodiment of the present invention is illustrated on the schematic circuit diagram of FIG. 9A.
  • the latter embodiment of the present isolated AC-DC power converter 900 can equally function as DC-AC inverter configured to transferring power from the illustrated DC supply source 26, e.g. a battery pack coupled to the Vout node 27, back to the AC input nodes 2, 3.
  • the illustrated DC supply source 26 e.g. a battery pack coupled to the Vout node 27, back to the AC input nodes 2, 3.
  • the present isolated AC-DC power converter 900 is config ured as a bidirectional isolated AC-DC power converter which may therefore be con figurable as an isolated DC-AC power converter by appropriate adaptation of a con trol circuit.
  • Such a bidirectional isolated AC-DC power converter 900 may be useful in power routing applications with battery storage.
  • One such application may com prise charging of the battery pack during off-peak hours and energy delivery back into the AC power grid during peak hours. Whether it is in charge or discharge mode, the same method of control of the bidirectional isolated AC-DC power con verter 900 may be utilized. Both the AC (primary) and battery pack (secondary) sides of the converter 900 are operated as current sources or sinks.
  • An exemplary embodiment of the controller 10 of the bidirectional isolated AC-DC power converter 900 is schematically illustrated on FIG. 9B. Used as a battery charger the bidirec tional isolated AC-DC power converter 900 may be viewed as a PFC input com bined with a current controlled LLC DC-DC converter.
  • the amount of current re quired and/or permitted from the DC-DC conversion function may be set by a battery charge controller circuit.
  • the PFC function of the bi-directional isolated AC-DC power converter 900 responds indirectly by regulating the input voltage across the DC input/link capacitor 7. All that is required to reverse operation and feed energy from the battery pack 26 to the AC source 1 is reversing the polarity of a control sig nal from the battery charge controller.
  • the DC-DC converter functionality in re sponse draws a controlled current from the battery pack 26 and the PFC converter functionality delivers a substantially sinusoidal current into the AC source 1. Another way of looking at this feature is to say that the input impedance seen by the AC source 1 is still resistive as usual but now negative.
  • the converter 900 is without electrical connection to the AC grid.
  • the converter 900 may advantageously be used to operate as an AC voltage source, e.g., an uninterruptable power supply (UPS) instead.
  • UPS uninterruptable power supply
  • An exemplary embodiment of the bidirectional isolated AC-DC power converter 900 configured for that type of application is schematically illustrated on FIG. 9C where the output volt age of the bidirectional isolated AC-DC power converter 900 preferably is regulated instead of the output current.
  • bidirectional isolated AC-DC power con verter 900 may be modified so as to exclusively operate as an isolated DC-AC power converter, for example embodied as a DC-AC inverter, using the above-out- lined reversal of the polarity of the control signal from the battery charge controller.
  • the bidirectional isolated AC-DC power converter 900 are obtained by coupling a series capacitor 15 into the primary side circuitry and also a series capacitor 15b into the secondary side circuitry as illus trated on FIGS. 9A, 9B, 9C.
  • the isolated AC-DC power converter 900 may be con figured as a bidirectional LLC which also regulates voltage in both directions. By its nature the primary side bridge comprising the first half bridge 14a and the second half bridge 14b already functions equally well in both directions of power transfer.
  • Such a bidirectional LLC circuit embodiment of the isolated AC-DC power converter 900 may be useful in power routing applications involving battery storage.

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

Abstract

La présente invention concerne, selon un aspect, un convertisseur de puissance c.a.-c.c. isolé comprenant des circuits latéraux primaires comprenant des premier et second nœuds d'entrée c.a. pouvant être connectés à une source de tension alternative pour la réception d'une tension d'entrée c.a. et des circuits latéraux secondaires comprenant des première et seconde sorties pouvant être connectées à une charge de convertisseur. La présente invention concerne, selon un autre aspect, un onduleur de puissance c.c.-c.a., tel qu'un onduleur de puissance c.c.-c.a. isolé.
PCT/EP2022/053894 2021-02-18 2022-02-17 Convertisseurs de puissance c.a.-cc et c.c.-c.a. isolés WO2022175365A1 (fr)

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EP21157754 2021-02-18

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10696182B2 (en) * 2014-06-13 2020-06-30 University Of Maryland, College Park Integrated dual-output grid-to-vehicle (G2V) and vehicle-to-grid (V2G) onboard charger for plug-in electric vehicles
US10819222B2 (en) * 2015-10-06 2020-10-27 Infineon Technologies Austria Ag Circuitry for power factor correction and methods of operation
FR3097384A1 (fr) * 2019-06-17 2020-12-18 Commissariat A L'energie Atomique Et Aux Energies Alternatives Dispositif d'alimentation à partir d'une tension alternative

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10696182B2 (en) * 2014-06-13 2020-06-30 University Of Maryland, College Park Integrated dual-output grid-to-vehicle (G2V) and vehicle-to-grid (V2G) onboard charger for plug-in electric vehicles
US10819222B2 (en) * 2015-10-06 2020-10-27 Infineon Technologies Austria Ag Circuitry for power factor correction and methods of operation
FR3097384A1 (fr) * 2019-06-17 2020-12-18 Commissariat A L'energie Atomique Et Aux Energies Alternatives Dispositif d'alimentation à partir d'une tension alternative

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