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WO2015173053A1 - Convertisseur à résonance permettant de générer une tension élevée et procédé permettant de commander un convertisseur à résonance - Google Patents

Convertisseur à résonance permettant de générer une tension élevée et procédé permettant de commander un convertisseur à résonance Download PDF

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Publication number
WO2015173053A1
WO2015173053A1 PCT/EP2015/059758 EP2015059758W WO2015173053A1 WO 2015173053 A1 WO2015173053 A1 WO 2015173053A1 EP 2015059758 W EP2015059758 W EP 2015059758W WO 2015173053 A1 WO2015173053 A1 WO 2015173053A1
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WO
WIPO (PCT)
Prior art keywords
resonant converter
variable
resonant
evaluated value
control
Prior art date
Application number
PCT/EP2015/059758
Other languages
English (en)
Inventor
Hendrik Huisman
Alexander Christiaan De Rijck
Ronald Hans Van Der Voort
Original Assignee
Koninklijke Philips N.V.
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.)
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Publication date
Application filed by Koninklijke Philips N.V. filed Critical Koninklijke Philips N.V.
Publication of WO2015173053A1 publication Critical patent/WO2015173053A1/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
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/42—Conversion of DC power input into AC power output without possibility of reversal
    • H02M7/44—Conversion of DC power input into AC power output without possibility of reversal by static converters
    • H02M7/48—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/505—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
    • H02M7/515—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
    • H02M7/523—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only with LC-resonance circuit in the main circuit
    • 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
    • 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
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/42—Conversion of DC power input into AC power output without possibility of reversal
    • H02M7/44—Conversion of DC power input into AC power output without possibility of reversal by static converters
    • H02M7/48—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/4815—Resonant 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

  • Resonant converter for high voltage generation and method for controlling a resonant converter
  • the present invention relates to the field of voltage conversion and generation. Particularly, the present invention relates to a resonant converter for high voltage generation and a method for controlling a resonant converter.
  • Resonant power converters are regularly used, in combination with a transformer, to produce isolated DC, direct current, voltages.
  • a transformer In a particular application, such a converter is used in combination with a Cockroft- Walton multiplier to produce the high DC voltages which are necessary to drive an X-Ray tube. Due to the presence of the transformer, AC, alternating current, voltage waveforms are required. Furthermore, in order to mitigate switching losses and electromagnetic interference (EMI), smooth voltage and current waveforms are preferred.
  • EMI electromagnetic interference
  • the voltage swing across the resonant capacitor can range from a maximum corresponding to the natural resonant frequency of the resonant tank, down to very small values - theoretically down to zero, corresponding to very (infinitely) high switching frequencies.
  • a shunting capacitor is connected across the AC terminals of the diode rectifier and/or the primary terminals of the transformer. This capacitor effectively shunts some of the current flowing in the resonant tank away from the output, thereby facilitating zero output current while a nonzero current flows in the resonant tank.
  • the resulting topology is denoted as LCC.
  • CLC capacitance-to-voltage
  • frequency control which is a well-known method, allows a very simple implementation.
  • frequency control suffers from ill-defined dynamic response, without guarantees to have sustained resonance in the circuit, or to avoid hard-switching events and voltage or current overshoots if challenging dynamic behavior is desired.
  • Other, more developed control methods suffer from these anomalies to a lesser extent, but still the control of resonant converters, especially under dynamically challenging conditions, is considered to be a difficult problem.
  • OTC optimal trajectory control
  • US 6,178,099 Bl describes a phase-shifted control for a series resonant converter involving instantaneous monitoring of state variables, e.g. resonant capacitor voltage, resonant inductor current and output voltage, and the implementation of a control law for providing a quasi-square-wave-with-maximum-coasting mode of operation.
  • the control law uses the instantaneous resonant inductor current, the instantaneous resonant capacitor voltage and the output voltage to determine the optimal time to perform switching events in order to operate on a desired control trajectory.
  • the quasi- square- wave- with- maximum-coasting converter operates at a minimized frequency in a super-resonant mode with zero-voltage switching, minimized electrical stresses, and reduced electromagnetic interference due to nearly sinusoidal resonant tank currents.
  • An aspect of the invention relates to a resonant converter for high voltage generation, the resonant converter comprising: at least one switch; a measuring unit, which is adapted to measure at least two variables, a first variable and a second variable, of the resonant converter on at least one state transition per cycle of the resonant converter; a processing unit, which is adapted to evaluate a control model of a circuit operation of the resonant converter using at least the measured first variable and at least one circuit parameter of the resonant converter generating an evaluated value; and to compare the evaluated value to at least the second variable, determining an instant at which the evaluated value and the measured at least the second variable cross; and a switching unit, which is adapted to control the at least one switch based on the determined instant and on the comparison of the evaluated value with the at least the second variable.
  • Each of the measured at least two variables may be any voltage or current of the circuit of the resonant converter, e.g. a measured quantity measured at different instants, defining a function over time, representing a time-dependency.
  • the evaluated value might be any kind of characteristic voltage or current of the circuit of the resonant converter, e.g. an evaluated quantity evaluated at different instants, defining a function over time, representing a time-dependency.
  • the determining of the instant at which the evaluated value and the measured second variable cross implies a determining of the instant at which a first or evaluated function over time of the evaluated value and a second or measured function over time of the measured second variable cross.
  • a further, second aspect of the invention relates to a high voltage generator for X-ray generation comprising at least one resonant converter according to any implementation form of the first aspect.
  • a further, third aspect of the present invention relates to an X-ray generator comprising a high voltage generator according to the second aspect.
  • a further aspect of the invention relates to a method for controlling a resonant converter, the method comprising the steps of: measuring at least two variables, a first variable and a second variable, of the resonant converter on at least one state transition per cycle of the resonant converter; evaluating a control model of a circuit operation of the resonant converter using the measured at least the first variable and at least one circuit parameter of the resonant converter generating an evaluated value and comparing the evaluated value to at least the second variable, determining an instant at which the evaluated value and the measured second variable cross; and controlling the at least one switch based on the determined instant and the comparison of the evaluated value with the second variable.
  • the present invention provides a non-linear control law which can be used to control LC, LCC, CLC, and CLCC series-resonant converters.
  • the control law is derived using first principles from circuit theory. Without loss of generality, only the case for the CLCC converter at positive current flow in the resonant circuit will be addressed.
  • the present invention advantageously provides a method which can be used to precisely control so-called LCC, CLC, and CLCC variants of resonant power converters.
  • the present invention advantageously makes use of parameters of the resonant tank circuit, the shunt capacitor (if present), and the device capacitances (if present), and measured voltages to predict the instant of switching such that a predefined peak voltage across the resonant capacitor is reached at the end of a resonant (half)cycle.
  • the present invention advantageously allows precisely reaching a predefined system state at the next relevant state transition.
  • Relevant state transitions could be, for example, the instants where the current in the resonant tank crosses zero, i.e. the instants at which the voltage in the resonant tank reaches a local maximum or minimum over time. In the time interval between these zero crossings, the operation can be described as a sequence of linear circuits, the configuration of which depends on the semiconductor switches which are conducting.
  • the present invention advantageously provides an optimal trajectory control law which can be used to precisely control the LCC, CLC and CLCC types of series-resonant converters. By using this control law, the peak voltage across the resonant capacitor can be accurately controlled to a desired value.
  • the present invention advantageously proposes considering a resonant inverter, which in steady state operation cyclically traverses through a limited number of system states. Circuit variables are measured at one state transition or more state transitions per cycle, for example at the zero crossings of the inductor current. Using these measured variables, the desired system state at the next relevant state transition, and a mathematical model of the circuit operation, a control value is evaluated directly after this measurement and stored.
  • a comparing of a measured circuit variable, defined as the measured variable, in time to the evaluated value is performed; a switching instant is derived implicitly and, correspondingly, an activating or deactivating of the at least one switch at this very instant leads to reaching exactly the desired system state at the next relevant state transition.
  • the method can be used for controlling resonant converters.
  • the term "switch" used within the description of the present invention may relate to a three-terminal power semiconductor device power transistor as a switch, in a single device.
  • the switch may be any power semiconductor switch, such as a GTO - gate turn-off thyristor -, a JFET - junction gate field-effect transistor-, a Bipolar transistor, an IGCT - Integrated Gate-Commutated Thyristor -, an IGBT - insulated-gate bipolar transistor -, or a MOSFET - metal oxide semiconductor field-effect transistor.
  • the switches may be used for resonant power conversion using CLC, LCC or CLCC type converters, for which accurate control of the power flow is needed, in particular for high voltage generators in the fields of interventional X-Ray and diagnostic X-Ray.
  • instant used within the description of the present invention may relate to a very short period of time, e.g. between 1 ns and 500 ns, or between 1 ns and 1000 ns, or between 1 ns and several hundreds of or several hundreds of ms.
  • instant may relate to a single, usually precise, point in time, relating to a switching event.
  • the processing unit is adapted to evaluate the control model by means of an analogue circuit.
  • the processing unit is adapted to evaluate the control model by means of a digital signal processor.
  • This advantageously provides an improved evaluating of the optimal switching time, providing optimized digital signal processing.
  • the processing unit is adapted to evaluate the control model by means of a field-programmable gate array (FPGA).
  • FPGA field-programmable gate array
  • the processing unit may be adapted to store a control value based on the comparison of the evaluated value with the measured variable.
  • the switching unit may be adapted to activate or to deactivate the at least one switch.
  • the processing unit is adapted to compare the evaluated value and the second variable at the instant where the evaluated value and the second variable cross.
  • control device is adapted to control an LC resonant converter, an LCC resonant converter, a CLC resonant converter, or a CLCC series-resonant converter, or any other resonant converter.
  • a computer program performing the method of the present invention may be stored on a computer-readable medium.
  • a computer-readable medium may be a floppy disk, a hard disk, a CD, a DVD, an USB (Universal Serial Bus) storage device, a RAM (Random Access Memory), a ROM (Read Only Memory) and an EPROM (Erasable Programmable Read Only Memory).
  • a computer-readable medium may also be a data communication network, for example the Internet, which allows downloading a program code.
  • DSP Digital Signal Processor
  • ASIC application specific integrated circuit
  • CPLD CPLD
  • Figure 1 shows a schematic diagram of a circuit of an LC resonant converter for explaining the invention
  • Figure 2 shows a schematic diagram of a simplified circuit of an LC resonant converter for explaining the invention
  • Figure 3 shows a schematic diagram of a control circuit for explaining the invention
  • Figure 4 shows a schematic diagram of a circuit of an LCC resonant converter for explaining the invention
  • Figure 5 shows a schematic diagram of frequency vs. rectifier current for an LC converter and a schematic diagram of frequency vs. rectifier current for an LCC converter for explaining the invention
  • Figure 6 shows schematic diagrams of circuits of CLC and CLCC resonant converters according to an exemplary embodiment of the invention
  • Figure 7 shows a schematic diagram of a simplified circuit of a CLCC resonant converter according to an exemplary embodiment of the invention
  • Figure 8 shows a schematic diagram of a circuit of a resonant converter according to an exemplary embodiment of the invention
  • Figure 9 shows a state plane plot and a signal versus time diagram for explaining the invention.
  • Figure 10 shows a schematic diagram of impressed load voltage, a set point for the peak capacitor voltage and the actual capacitor voltage and the capacitor current for explaining the invention
  • Figure 11 shows a schematic flowchart diagram of a method for a resonant converter according to an exemplary embodiment of the invention
  • Figure 12 shows a schematic diagram of a resonant converter according to an exemplary embodiment of the invention.
  • Figure 13 shows a schematic diagram of an X-ray generator according to an exemplary embodiment of the invention.
  • Figure 1 shows a schematic diagram of a circuit of a resonant converter for explaining the invention.
  • Figure 1 shows a circuit of a resonant converter. Also other circuits for resonant converters may be used. In particular, other switching devices, such as MOSFETs, can be used instead of the IGBT devices in form of the switches 40 shown here, a half-bridge inverter circuit can be used, and other configurations of the voltage multiplier are possible.
  • switching devices such as MOSFETs
  • MOSFETs can be used instead of the IGBT devices in form of the switches 40 shown here
  • a half-bridge inverter circuit can be used, and other configurations of the voltage multiplier are possible.
  • Figure 2 shows a schematic diagram of a circuit of a resonant converter for explaining the invention.
  • This high DC voltage is defined by the difference in charges delivered to, and taken out of, the output capacitance, i.e. Cload in the circuit shown in Figure 2, of the high voltage generating circuit.
  • the current delivered to the load circuit i.e. the rectifier current Irect as indicated in Figure 2, can be used to control this voltage to a desired value. Control of this current is therefore a prerequisite to control of the high DC voltage at the output.
  • Figure 3 shows a schematic diagram of a control circuit for explaining the invention.
  • the resulting control error is further processed by a controller to generate a set point value for the rectifier current "Irect".
  • This current serves to charge the load circuit consisting of "Cload” and “Rload” to the desired load voltage.
  • This control loop will, where necessary, be denoted as the outer or voltage control loop.
  • the controlled current source "Irect” here represents the averaged operation of the resonant converter, including the output rectifier, as depicted in Figure 2.
  • the swing of the voltage across the capacitor in the resonant tank is precisely controlled for every individual half-cycle of the resonant current. Thereby, also the charge which is displaced in the resonant tank is precisely defined for such a half cycle. Due to the series connection of resonant tank and rectifier, the charge per (half) cycle which the rectifier delivers to the load is also defined. In fact, assuming a linear capacitance Cres, the relation between the voltage swing across this capacitor and the charge delivered to the load is linear.
  • Figure 4 shows a schematic diagram of a circuit of a resonant converter for explaining the invention.
  • X-Ray tube loads are driven under a wide variety of conditions.
  • Limiting cases are restricted time spans (in the order of tens of milliseconds) at maximum current and high voltage (power pulse mode), and extended time spans (many seconds) over a range of output voltages and at very small current (less than 1% of the maximum).
  • Figure 5 shows a schematic diagram of frequency vs. rectifier current for an
  • the rectifier current in the LCC now indeed reaches zero for a finite value of the operating frequency.
  • FIG. 6 shows a schematic diagram of a circuit of a resonant converter 200 according to an exemplary embodiment of the invention.
  • the circuit as shown in the left panel of Figure 6 will in the following be referred to as CLC converter, and for its counterpart in Figure 6 in the right panel, the label CLCC will be used.
  • (C)LCC converters are especially interesting in the context of generation of high DC voltages, such as used in X-Ray equipment.
  • the transformer used in such apparatus typically has a very large winding ratio, and thereby unavoidably features a relatively large parasitic input capacitance.
  • this capacitance can be incorporated as a functional element of the power converter.
  • the invention allows controlling such an (C)LCC converter with a similar level of accuracy as in the already established case of the LC converter.
  • Figure 7 shows a schematic diagram of a circuit of a resonant converter 200 according to an exemplary embodiment of the invention.
  • Figure 7 shows a full bridge circuit with resonant tank and load rectifier.
  • the circuit as shown in Figure 7 represents a resonant converter 200 for high voltage generation, the resonant converter 200 comprising: at least one switch 40, a measuring unit 10, a processing unit 20, and a switching unit 30.
  • the load circuit has been redrawn here as a voltage source, as it is assumed that the change in output voltage in one half cycle of resonant current is small enough to be neglected. If this would not be the case, the circuit would feature relatively high ripple at the output, which is in general not desired.
  • switches QAl and QB2 are opened and closed synchronously, as are switches QA2 and QBl . Furthermore, the top switches (QAl and QBl) are opened and closed in perfect counter phase to their bottom companions (QA2 and QB2 respectively).
  • Vdc or -Vdc is applied to the left-side terminals of the resonant tank consisting of Lres and Cres. In other words, only two different voltages are produced by the full bridge.
  • a third voltage which can be generated by the full bridge is also used.
  • This voltage ideally equal to zero (hence called a zero vector), can be produced by enabling either the top switches (QAl, QBl) or the bottom switches (QA2, QB2) at the same time.
  • Using unipolar switching has slight advantages with respect to the current stress applied to the power semiconductors, but shows distinct disadvantages in view of the EMI behavior of the circuit.
  • Using unipolar switching introduces a common-mode voltage across the load circuit, leading to significant currents flowing through various parasitic capacitances.
  • the only variable which can be directly influenced by the controller for the inner (current) loop is the instant when the voltage commutation is initiated, i.e. when the power semiconductors in the full bridge as shown in Figure 7 are turned off.
  • the switching unit 30 is adapted to control the at least one switch 40 based on the determined instant and on the comparison of the evaluated value with the second variable.
  • the switching unit 30, due to the input received from the measuring unit 10 and from the processing unit 20, provides optimum switching control for operating the resonant converter at the resonant frequency.
  • the switching unit 30 can control power delivered to a load by varying its switching frequency to an optimum resonant frequency of the resonant converter, providing the optimum control of at least one switch 40 switch transitions will be more efficient. This fact allows operation at very high frequency without an appreciable loss of converter efficiency, and, consequently, yields a converter with very high power density.
  • the task of the switching unit 30 is to attain a desired value for the voltage swing across the resonant capacitor (i.e. the net charge displaced during a half cycle of the operation).
  • the voltage across the resonant capacitor (Cres) will be denoted as Vc.
  • the control law can be defined as a mathematical algorithm using the initial value of the resonant capacitor voltage (Vcinit), its desired final value (Vcend), and various circuit variables and parameters to define this very instant.
  • Vcinit initial value of the resonant capacitor voltage
  • Vcend desired final value
  • One method comprises calculating Vccomm, i.e. the value of the voltage across the resonant capacitor at the desired start of voltage commutation.
  • the parameters used may include the extra shunt and device capacitances.
  • Vcend A summation of Vcend, doubled VDC, and doubled Vload is multiplied with Vcend, a summation of negative Vcinit, doubled VDC, and doubled negative Vload is multiplied with Vcinit, both sums are added together and then divided by the fourfold of VDC, subtracted from this value is Cr multiplied with VDC and divided by doubled Cres, further subtracted from this value is Cmain multiplied with the square of Vload and divided by Cres multiplied with VDC:
  • V Cend (V Cend + 2V DC + 2V load ) + V cinit ⁇ — V init + 2VD 2V IOAD ) C r CmaivYloa d
  • Vccomm — —— V dc —
  • This value can be calculated either at the beginning of the resonant half cycle only, or continuously during the current flow. By comparing the actual voltage across the resonant capacitor, which is by definition a continuous and monotonously rising function of time, to this value the commutation instant can be found in real time.
  • Figure 8 shows a schematic diagram of a circuit of a resonant converter according to an exemplary embodiment of the invention.
  • Figure 8 shows, an active part of circuit during voltage commutation.
  • Figure 8 shows also once again, the same active part of circuit during voltage commutation, however, with node capacitances combined.
  • Figure 9 shows a schematic diagram of a state plane plot and a signal versus time diagram for explaining the invention.
  • An example of the operation of the control law is shown in Figure 9. This example has been produced by simulation.
  • Vcinit equals -100 V.
  • the target for Vcend is set to 100 V.
  • the output diodes start conducting.
  • Vc reaches Vccomm, all power semiconductors are turned off, and the voltage commutation starts. After the voltage commutation, the current decreases, and the capacitor voltage exactly reaches its intended value at the instant where Ic equals zero.
  • Unipolar switching implies that the voltage commutations of both phase legs do not coincide in time.
  • An extra degree of freedom exists in this the duration of the interval where a zero vector is produced can be chosen freely, bounded to the extreme cases where the first voltage commutation starts immediately at the beginning of the positive half cycle, or where the second voltage commutation finishes at the end of the half cycle.
  • VccommA and VccommB indicate the voltages across Cres at the start of commutation of phase legs A and B, respectively.
  • the entries of the control model partly consist of circuit variables which need to be measured (the various voltages), and partly on circuit parameters (i.e. the capacitor values).
  • control model can be evaluated in real time using an analogue circuit consisting of multipliers and operational amplifiers.
  • Another method could be to sample the necessary signals at a high rate and convert them to the digital domain, and subsequently evaluate the control model digitally by means of a Digital Signal Processor (DSP), Field Programmable Gate Array (FPGA), or similar device.
  • DSP Digital Signal Processor
  • FPGA Field Programmable Gate Array
  • Yet another method would be to calculate the control model at the beginning of the current flow only, and store the thus calculated value for Vccomm for continuous comparison to the actual measured capacitor voltage.
  • An interesting variation on this method would be to convert the calculated value for Vccomm back to the analogue domain by means of a D/A converter, and perform the comparison needed to find the commutation instant in the analogue domain.
  • Such a setup would avoid the need for very fast sampling and converting of analogue signals, and could be used at relatively low cost up to high frequencies.
  • states 1 up to 3 correspond to positive values of Ic, and states 4 up to 6 to negative values. Only the conditions which are valid in normal operation are listed in the following.
  • a second state all switches are off, the condition for changing to a third state then is that the voltage commutation is finished.
  • DA2 and are DB1 on the condition for changing to a fourth state then is that lc ⁇ 0.
  • a fifth state all switches are off, the condition for changing to a sixth state then is that the voltage commutation is finished.
  • DAI and DB2 are on, the condition for changing to a first state then is that lc>0.
  • Figure 10 shows a schematic diagram of impressed load voltages, a set point for the peak capacitor voltage and actual capacitor voltage and the capacitor current for explaining the invention.
  • the set point value for the peak capacitor voltage and the output voltage can be changed step-wise in order to illustrate the operation of the control algorithm. Note that changing the output voltage step-wise is not possible in most practical circuits, this particular feature is only used here to show the robustness of the control law to such harsh environments. The results are shown in Figure 10.
  • Figure 10 shows in the top trace: impressed load voltage, in the middle traces: set point for the peak capacitor voltage (both positive and negative) and actual capacitor voltage, in the lower trace: capacitor current.
  • the peak capacitor voltage indeed closely follows its set point. Exceptions are visible in the cases where either the impressed load voltage or the set point changes in a time interval where corrective action is not immediately possible, i.e. shortly after a voltage commutation.
  • Figure 11 shows a schematic flowchart diagram of a method for a resonant converter according to an exemplary embodiment of the invention.
  • the method for controlling a resonant converter may comprise the following steps of: As a first step of the method, measuring SI at least two variables, a first variable and a second variable, of the resonant converter 200 on at least one state transition per cycle of the resonant converter 200 is conducted.
  • a parameter of an extra shunt or any kind of device capacitances may be used.
  • controlling S3 the at least one switch 40 based on the determined instant and the comparison of the evaluated value with the second variable is conducted.
  • these steps may be carried out simultaneously, divided into multiple operations or tasks or iteratively repeated.
  • the iteration of the steps may be implemented recursively, by count-controlled loops or by condition-controlled loops.
  • control model of the circuit operation of the resonant converter may be defined for every other sub-interval of the circuit operation, by using the following connecting equations:
  • Vcmain is equal to -Vload
  • Vload is equal to Vload
  • Vload is equal to Vload
  • Vdc the final value to zero
  • V(CrAl) and V(CrB2) are equal to zero, and the final value to Vdc.
  • Capacitors when connected in series process the same charge and the change in their voltage is therefore inversely proportional to their capacitance value.
  • Figure 12 shows a schematic diagram of a resonant converter 200 according to an exemplary embodiment of the invention.
  • the resonant converter 200 may comprise: at least one switch 40, a measuring unit 10, a processing unit 20, and a switching unit 30.
  • a computer program or a computer program element is provided that is characterized by being adapted to execute the method steps of the method according to one of the preceding embodiments, on an appropriate system.
  • Figure 13 shows a schematic diagram of an X-ray generator according to an exemplary embodiment of the invention.
  • a high voltage generator 300 for X-ray generation may comprise at least one resonant converter 200.
  • An X-ray generator 400 may comprise a high voltage generator 300.
  • the computer program element might therefore be stored on a computer unit, which might also be part of an embodiment of the present invention.
  • This computing unit may be adapted to perform or induce a performing of the steps of the method described above.
  • the computing unit can be adapted to operate automatically and/or to execute the orders of a user.
  • a computer program may be loaded into a working memory of a data processor.
  • the data processor may thus be equipped to carry out the method of the invention.
  • This exemplary embodiment of the invention covers both, a computer program that right from the beginning uses the invention and a computer program that by means of an up-date turns an existing program into a program that uses the invention.
  • the computer program element might be able to provide all necessary steps to fulfill the procedure of an exemplary embodiment of the method as described above.
  • a computer readable medium such as a CD-ROM
  • the computer readable medium has a computer program element stored on it, which computer program element is described by the preceding section.
  • a computer program may be stored and/or distributed on a suitable medium, such as an optical storage medium or a solid state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the internet or other wired or wireless telecommunication systems.
  • a suitable medium such as an optical storage medium or a solid state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the internet or other wired or wireless telecommunication systems.
  • the computer program may also be presented over a network like the World Wide Web and can be downloaded into the working memory of a data processor from such a network.
  • a medium for making a computer program element available for downloading is provided, which computer program element is arranged to perform a method according to one of the previously described embodiments of the invention.

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

Abstract

La présente invention se rapporte à un convertisseur à résonance (200) permettant de générer une tension élevée, le convertisseur à résonance (200) comprenant : au moins un commutateur (40); une unité de mesure (10), qui est adaptée pour mesurer au moins deux variables, une première variable et une seconde variable, du convertisseur à résonance (200) sur au moins une transition d'état par cycle du convertisseur à résonance (200); une unité de traitement (20), qui est adaptée pour évaluer un modèle de commande du fonctionnement d'un circuit du convertisseur à résonance (200) en utilisant au moins la première variable mesurée et au moins un paramètre de circuit du convertisseur à résonance et générer ainsi une valeur évaluée, et pour comparer la valeur évaluée à au moins la seconde variable, ce qui permet de déterminer un instant où se coupent la valeur évaluée et la seconde variable mesurée; et une unité de commutation (30), qui est adaptée pour commander le ou les commutateurs (40) en se basant sur l'instant déterminé et sur la comparaison entre la valeur évaluée et la seconde variable.
PCT/EP2015/059758 2014-05-16 2015-05-05 Convertisseur à résonance permettant de générer une tension élevée et procédé permettant de commander un convertisseur à résonance WO2015173053A1 (fr)

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EP14168633.7 2014-05-16
EP14168633 2014-05-16

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WO2015173053A1 true WO2015173053A1 (fr) 2015-11-19

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110199575A (zh) * 2017-01-19 2019-09-03 皇家飞利浦有限公司 用于生成x射线辐射的x射线源装置
EP4228135A1 (fr) * 2022-02-14 2023-08-16 Delta Electronics (Shanghai) Co., Ltd. Procédé d'estimation de paramètres de convertisseur résonant, procédé de commande de convertisseur résonant et convertisseur résonant
CN119416593A (zh) * 2025-01-07 2025-02-11 国网上海市电力公司 一种用于故障分析的clcc换流器多物理场仿真方法及系统

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4897775A (en) * 1986-06-16 1990-01-30 Robert F. Frijouf Control circuit for resonant converters
US5010471A (en) * 1989-06-26 1991-04-23 Robert F. Frijouf Three-phase AC-to-AC series resonant power converter with reduced number of switches
US5270914A (en) * 1992-01-10 1993-12-14 Lauw Hian K Series resonant converter control system and method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4897775A (en) * 1986-06-16 1990-01-30 Robert F. Frijouf Control circuit for resonant converters
US5010471A (en) * 1989-06-26 1991-04-23 Robert F. Frijouf Three-phase AC-to-AC series resonant power converter with reduced number of switches
US5270914A (en) * 1992-01-10 1993-12-14 Lauw Hian K Series resonant converter control system and method

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110199575A (zh) * 2017-01-19 2019-09-03 皇家飞利浦有限公司 用于生成x射线辐射的x射线源装置
EP4228135A1 (fr) * 2022-02-14 2023-08-16 Delta Electronics (Shanghai) Co., Ltd. Procédé d'estimation de paramètres de convertisseur résonant, procédé de commande de convertisseur résonant et convertisseur résonant
CN119416593A (zh) * 2025-01-07 2025-02-11 国网上海市电力公司 一种用于故障分析的clcc换流器多物理场仿真方法及系统

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