CN114785157A - AC-DC-AC converter for online UPS and control method thereof - Google Patents
AC-DC-AC converter for online UPS and control method thereof Download PDFInfo
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- 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
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
- H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
- H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
- H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
- H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
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- 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
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
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- 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
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc 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 triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc 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 triode or transistor type requiring continuous application of a control signal using semiconductor devices only
-
- 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
- H02M7/53—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 triode or transistor type requiring continuous application of a control signal
- H02M7/537—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 triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
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Abstract
An AC-DC-AC converter for on-line UPS comprises an AC input voltage source Vin, a first power switch tube S1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8An input inductor LinOutput inductor LoutBus capacitor Cbus(ii) a According to the different polarities of the input voltage, the rectification stage works in a boost modeA formula or buck-boost mode; the rectifying stage passes the third power switch S during the positive half-cycle of the input voltage3Keep on and let the fourth power switch tube S4Kept off while switching the first power switch S with a high switching frequency1And the second power switch tube S2At the moment, the rectification stage works in a boost mode; soft switching is achieved and allows high frequency operation, reducing the volume of the input inductance.
Description
Technical Field
The invention relates to an AC-DC-AC converter for an online UPS (uninterrupted power supply) and a control strategy thereof, belonging to the technical field of power electronic converters, in particular to the technical field of high-power-density Uninterrupted Power Supplies (UPS).
Background
Uninterruptible Power Supplies (UPS) can provide a backup power source for important loads during grid outages and disturbances. UPSs can be classified into three types, i.e., backup UPS, online interactive UPS, and online UPS. The backup UPS uses a static switch to connect the input directly to the output during normal operation of the grid while charging the battery, and the static switch is disconnected when the grid fails, the battery supplying power to the load through the inverter. Since the inverter operates only in the standby mode, the switching time is long and the protection against input disturbances during normal operation is small. In industrial environments, online interactive UPS's are more popular, and during normal operation, most line disturbances can be filtered by connecting the load with a passive regulation stage, and when a grid fails, the grid is disconnected by a series switch before the inverter is operated, with a switching time of a few milliseconds. The online UPS type firstly converts the voltage of a power grid into the direct-current voltage on the middle direct-current bus, then converts the voltage of the direct-current bus into the alternating-current voltage with the amplitude and the frequency required by the load at the output end, and the load is always supplied with power by the inverter stage, thereby ensuring the uninterrupted alternating-current voltage on the load. Online UPSs are commonly used in the field of safe and continuous operation of electronic devices, and have high requirements on the power density of the UPS.
In the prior art, transformer isolation topologies and single DC bus have been proposed, in which isolation requirements are usually met by using an isolation PFC rectifier stage, and three-stage isolated online UPS have been proposed, in which an additional DC-DC conversion stage is used before the PFC rectifier stage to meet the isolation requirements. In the above technique, the peak rated transformer limits its efficiency and adversely affects power density. For non-isolated online UPS, topologies have been proposed in which there is a common neutral point between the input and output anxiety ports, and these topologies use four-quadrant switches to limit their operating frequency, with split dc busses. The requirements for capacitance can be doubled, limiting their overall power density, or increasing the complexity of their control.
Disclosure of Invention
To overcome the above-mentioned disadvantages of the prior art, it is an object of the present invention to provide an AC-DC-AC converter for an online UPS and a control method thereof, which have the characteristics of realizing soft switching, allowing high frequency operation, and reducing the size of an input inductor.
In order to realize the purpose, the invention adopts the technical scheme that:
an AC-DC-AC converter for online UPS comprises an AC input voltage source Vin, a first power switch tube S1A second power switch tube S2The third power switch tube S3Fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8An input inductor LinAn output inductor LoutBus capacitor Cbus；
The first end of the AC input voltage source Vin and the third power switch tube S3Is connected with the second end of the AC input voltage source Vin and the first power switch tube S1Source electrode and bus capacitor CbusSecond terminal and sixth power switch tube S6The source electrodes of the first and second switches are all connected with the second end of the output end; third power switch tube S3And a fourth power switch tube S4Source and input inductor L ofinAre all connected; input inductance LinAnd a second terminal of the second power switch tube S2Source electrode of and first power switch tube S1The drain electrodes of the two transistors are connected; fourth power switch tube S4And a second power switch tube S2Drain electrode and bus capacitor CbusAre all connected; fifth power switch tube S5Drain electrode of and seventh power switch tube S7Is connected with the drain electrode of the transistor; fifth power switch tube S5Source electrode of (1) and sixth power switch tube S6Drain and output inductor LoutIs connected; seventh power switch tube S7Source electrode of (1) and eighth power switch tube S8Drain of and output inductor LoutThe second ends of the two are connected; eighth power switch tube S8Is connected to the first end of the output terminal.
The first power switch tube S1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8Are all SiCMOS switch tubes.
The first power switch tube S1A second power switch tube S2The third power switch tube S3Fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8Are provided with diodes connected in parallel.
The first power switch tube S1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8Driven by complementary pulses.
The first power switch tube S1A second power switch tube S2The third power switch tube S3Fourth power switch tube S4Constituting the rectifier stage of the converter.
The first power switch tube S1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4The soft switch can realize zero voltage switching.
The fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7Forming the inverter stage of the transformer.
A method of controlling an AC-DC-AC converter for an online UPS, comprising the steps of:
for the control of the rectification stage, the rectification stage of the converter works in two working modes of boost and buck-boost, and the converter runs at high frequency in order to reduce the size of the input inductor; in order to keep high efficiency under high switching frequency, the rectification stage works in a boundary conduction mode to operate, so that the power switching tube is switched on at zero voltage;
in the positive half period of the input voltage, the rectification stage operates in a boost mode, and the instantaneous value of the input voltage is less than half of the direct current bus voltage; when the instantaneous value of the input voltage is greater than half the dc bus voltage, only the inductor current at the end of each switching cycle is less than a negative value iboostminWhen the switch is turned on, zero voltage switching-on can be realized; cOSSIs a first power switch tube S1And a second power switch tube S2The parasitic capacitance of (2); second power switch tube S2The first power switch tube S can be ensured to be connected after the inductive current is zero-crossed for a period of time to establish the required negative inductive current1The zero voltage of (1) is turned on;
during the negative half-cycle of the input voltage, the rectifier stage operates in buck-boost mode, the third power switch S3And a fourth power switch tube S4Naturally realizing zero voltage switching-on, when the instantaneous value of the input voltage is less than the bus voltage, the third power switch tube S3And a fourth power switch tube S4The buck-boost converter is always operated in boost mode, and in the boost mode, the third power switch tube S3Without the need for a fourth power switch S4Turned on for a period of time to achieve zero voltage turn-on.
In the control of the whole rectification stage, the rectification stage works in a boundary conduction mode, and controls the first power switch tube S by sensing the polarity of the input voltage1A second power switch tube S2The third power switch tube S3Fourth power switch tube S4A drive signal of the gate; when the input voltage is greater than zero, the first power switch tube S1First turn on tonboostThen the second power switch tube S2Is turned on until the current of the inductor drops to iboostminThe following; when the input voltage is less than zero, the third power switch tube S3First on tonbuck-boostThen the fourth power switch tube S4Switching on until the inductor current reaches zero; a zero current detection circuit is needed in the whole control, the zero current detection circuit induces an inductive current, and two hysteresis comparators are utilized, and each half input period corresponds to one hysteresis comparator; in the positive half period of the input voltage, the inductor current drops to iboostminWhen the inductive current reaches zero in the negative half cycle of the input voltage, the hysteresis trigger generates a trigger signal, and the controller resets the PWM counter and starts the next switching cycle by detecting the trigger signal in each half cycle; the output voltage of the rectifier stage is regulated by the low-bandwidth voltage loop of the PI controller to control the first power switch tube S1And a third power switch tube S3On-time of (d);
for the control of the inversion stage, the inversion stage is mainly used for generating sinusoidal alternating-current voltage at the output end, and the inversion stage also works in two working modes, namely boost and buck-boost; the inverter stage works in a continuous conduction mode with fixed switching frequency;
in the whole inversion stage control, a sinusoidal reference voltage is compared with a detected output voltage to generate a voltage error signal, and the voltage error signal is sent to a controller of an inversion stage, wherein the controller of the inversion stage comprises two controllers GcbuckAnd Gcbuck-boost(ii) a When the output voltage is greater than zero, the controller G of buckcbuckControlling a fifth power switch transistor S5Duty cycle of (1), buck-boost controller Gcbuck-boostThe output of the eighth power switch tube is ignored, and the eighth power switch tube is kept on; when the output voltage is less than zero, buck-boost controller Gcbuck-boostController G for controlling duty ratio and buck of seventh power switch tubecbuckThe output of (c) is ignored and the sixth power switch remains on.
And a single direct current bus is used between the rectification stage and the inversion stage.
Compared with the prior art, the invention has the following beneficial effects:
the use of a single DC bus between the rectification and inversion stages of an AC-DC-AC converter for an online UPS reduces the capacitance requirement of the DC bus by 50% compared to a conventional discrete DC bus online UPS. The input rectifying stage of the converter operates in BCM mode, enables soft switching and allows high frequency operation, reducing the size of the input inductance. The output inverter stage operates in a CCM mode, and the controller adjusts the output voltage of the converter through a resistor and a reactive load. The converter is suitable for a charge-discharge interface of an integrated battery, the battery interface utilizes a main power level in a discharge stage, a peak power rated discharge stage is not needed, and a buck converter with lower rated power is used in the charging process. Thereby achieving high efficiency and high power density.
A single direct current bus is used between the rectification stage and the inversion stage, and compared with a traditional online UPS (uninterrupted power supply) with a discrete direct current bus, the capacitance requirement of the direct current bus is reduced by 50%; the rectifying stage of the input of the converter operates in BCM mode, enables soft switching and allows high frequency operation, reducing the size of the input inductance. The output inverter stage runs in a CCM mode, and the controller adjusts the output voltage of the converter through a resistor and a reactive load; the converter is suitable for a charge-discharge interface of an integrated battery, the battery interface utilizes a main power level in a discharge stage, a peak power rated discharge stage is not needed, and a buck converter with lower rated power is used during charging, so that high efficiency and high power density are realized.
Drawings
FIG. 1 is a block diagram of the topology of an AC-DC-AC converter for an online UPS of the present invention;
FIG. 2 is a schematic diagram of the operating mode of the present invention during the positive half cycle of the input voltage during the rectification phase;
FIG. 3 is a schematic diagram of the operation of the present invention during the negative half cycle of the input voltage during the rectification phase;
FIG. 4 is a schematic diagram of the operating mode of the present invention during the positive half cycle of the output voltage during the inversion phase;
FIG. 5 is a diagram of the operating mode of the negative half cycle of the output voltage during the inversion stage of the present invention;
fig. 6 is a time-enlarged view of the inductor current and a waveform diagram of the inductor current average value and a waveform diagram of the input voltage. Wherein, the sine solid line is a waveform diagram of input voltage, the sawtooth solid line is a time enlarged diagram of inductive current, and the sine broken line is a waveform diagram of the average value of inductive current;
FIG. 7 is a controller block diagram of a rectification stage;
FIG. 8 is a control block diagram of a zero current detection circuit for the rectification phase;
FIG. 9 is a block diagram of the controller during the inversion phase;
FIG. 10 is a battery charging path in a normal operating mode of the battery interface architecture diagram;
FIG. 11 is a battery discharge path in a standby mode of operation of the battery interface architecture diagram;
wherein: vin is an input voltage source; s1 is a first power switch tube; s2 is a second power switch tube; s3 is a third power switch tube; s4 is a fourth power switch tube; s5 is a fifth power switch tube; s6 is a sixth power switch tube; s7 is the seventh power switch tube; s8 is the eighth power switch tube; cbusIs a bus capacitor; cinIs an input capacitance; coutIs an output capacitor; l isinIs an input inductance; l is a radical of an alcoholoutIs an output inductor; l is a radical of an alcoholbatA battery side inductor; s. theb1A first power switch tube at the battery side; s. theb2A second power switch tube at the battery side; sR1Is a first quick relay; s. theR2A second quick relay; vout is the output voltage.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention is described in further detail below with reference to the accompanying drawings:
referring to fig. 1, a topology structure diagram of an AC-DC-AC converter for an online UPS according to the present invention includes an AC input voltage source Vin, a first power switch S1A second power switch tube S2The third power switch tube S3Fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8An input inductor LinAn output inductor LoutBus capacitor Cbus；
First end of AC input voltage source Vin and third power switch tube S3Is connected with the second end of the AC input voltage source Vin and the first power switch tube S1Source and bus capacitor CbusAnd a sixth power switch tube S6The source electrodes of the first and second transistors are connected with the second end of the output end; third power switch tube S3And the fourth power switch tube S4Source and input inductance LinAre all connected; input inductance LinSecond terminal and second power switch tube S2Source electrode and first power switch tube S1The drain electrodes of the two transistors are connected; fourth power switch tube S4And a second power switch tube S2And a drain electrode ofBus capacitor CbusFirst terminal and fifth power switch tube S5Drain electrode of and seventh power switch tube S7The drain electrodes of the two transistors are connected; fifth power switch tube S5Source and sixth power switch tube S6Drain electrode of (2) and output inductor LoutAre all connected; seventh power switch tube S7Source and eighth power switch tube S8Drain electrode of (2) and output inductor LoutThe second ends of the two are connected; eighth power switch tube S8Is connected to the first end of the output terminal.
Referring to fig. 2, which is a diagram of an operation mode of the present invention in a positive half cycle of an input voltage during a rectification stage, the rectification stage operates in a boost mode or a buck-boost mode according to a polarity of the input voltage. The rectifying stage passes the third power switch S during the positive half-cycle of the input voltage3Keep on and let the fourth power switch tube S4Kept off while switching the first power switch S with a high switching frequency1And the second power switch tube S2The commutation phase now operates in boost mode.
Referring to fig. 3, which is a diagram of the operation mode of the negative half cycle of the input voltage in the rectification stage of the present invention, the rectification stage passes through the first power switch S during the negative half cycle of the input voltage1Keep on and let the second power switch tube S2Kept off while switching the third power switch S with a high switching frequency3And the fourth power switch tube S4And at the moment, the rectification stage works in buck-boost mode. For low power applications, the second power switch tube and the fourth power switch tube can be replaced by power diodes, and the complexity of grid drive can be reduced. The boost and buck-boost modes of the rectifier stage are controlled during respective half cycles to regulate the dc bus voltage while drawing a sinusoidal current from the input at unity power factor.
Referring to fig. 4, which is a working mode diagram of the positive half cycle of the output voltage in the inversion stage of the present invention, in order to generate a positive output voltage at the output terminal, the inversion stage passes through the eighth stagePower switch tube S8Keep on and let the seventh power switch tube S7Keep the switch-off, and simultaneously switch the fifth power switch tube S with high switching frequency5And the sixth power switch tube S6And at the moment, the inversion stage works in buck mode.
Referring to fig. 5, which is a diagram of the operation mode of the negative half cycle of the output voltage in the inversion stage of the present invention, in order to generate a negative output voltage at the output terminal, the inversion stage passes through the sixth power switch tube S6Keep on and let the fifth power switch tube S5Keeping off, and simultaneously switching the seventh power switch tube S with a high switching frequency7And the eighth power switch tube S8And the inversion stage works in buck-boost mode. The boost mode and buck-boost mode of the inverter stage are controlled during their respective half cycles to produce the desired sinusoidal ac voltage at the output port.
Referring to fig. 6, a time-enlarged view of the inductor current and a waveform diagram of the average value of the inductor current and a waveform diagram of the input voltage are shown. The solid sine line is a waveform diagram of the input voltage, the solid sawtooth line is a time enlarged diagram of the inductive current, and the dashed sine line is a waveform diagram of the average value of the inductive current. During the positive half-cycle of the input voltage, the rectification phase operates in boost mode when the instantaneous value of the input voltage is less than half the voltage of the dc bus. When the instantaneous value of the input voltage is greater than half the bus voltage, the inductor current is less than i only at the end of each switching cycleboostminThen, zero voltage turn-on can be realized. Therefore, the second power switch tube S2Keeping on for a period of time after the inductor current crosses zero to establish the required negative inductor current, thereby ensuring that the first power switch tube S1And the second power switch tube S2The zero voltage of (c) is on. During the negative half period of the input voltage, the rectification stage works in buck-boost mode, and the third power switch tube S3And the fourth power switch tube S4And naturally realizing zero voltage switching-on. When the input voltage is less than the bus voltage, the power supply device works in a boost mode in buck-boost mode, and in the boost mode, the third power switch tube S3Does not require the fourth power switch tube S4An additional turn-on period of time is used to achieve zero voltage turn-on.
Referring to fig. 7, a block diagram of a controller of a rectification stage is shown, in which the rectification stage operates in a BCM mode, and the controller is a first power switch S by sensing the polarity of an input voltage1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4Generating a gate driving signal. When in the positive half period of the input voltage, the first power switch tube S1Is turned on tonboostThen, the second power switch tube S2Is turned on until the inductor current drops to iboostminThe following. When in the negative half period of the input voltage, the third power switch tube S3Is turned on tonbuck-boostThen, a fourth power switch tube S4Switched on until the inductor current reaches zero.
Referring to fig. 8, which is a control block diagram of the zero current detection circuit for the rectification stage, the zero current detection circuit senses the inductor current and utilizes two hysteretic comparators, one for each half of the input cycle. For the positive half period of the input voltage, when the inductive current drops to iboostminIn the following, the hysteretic comparator will generate a trigger signal, and similarly in the negative half-cycle of the input voltage, when the inductor current reaches zero, the hysteretic trigger will generate a trigger signal, and the controller will reset the PWM counter and start the next switching cycle by detecting the trigger signal in each half-cycle. The output voltage of the rectifier stage is regulated by a low-bandwidth voltage loop of the PI controller to output a first power switch tube S1And a third power switch tube S3The on-time of (c).
Referring to fig. 9, which is a block diagram of a controller in an inversion stage, for the control in the inversion stage, the inversion stage is mainly used for generating a sinusoidal ac voltage at an output terminal, and the inversion stage also operates in two operating modes, i.e., boost and buck-boost. The inverter stage operates in Continuous Conduction Mode (CCM) with a fixed switching frequency. For the whole inversion stage control, the sine reference voltage is compared with the detected output voltageThe generated voltage error signal is fed into a controller of an inverter stage, which comprises two controllers and GcbuckAnd Gcbuck-boost. For positive output voltage half-cycle, buck controller GcbuckGenerating and controlling the fifth power switch tube S5Duty cycle of (1), buck-boost controller Gcbuck-boostIs ignored, the eighth power switch tube S8Remain on. For negative output voltage half-cycle, buck-boost controller Gcbuck-boostGenerating and controlling the seventh power switch tube S7Duty cycle of (1), buck controller GcbuckIs ignored, the sixth power switch tube S6Remain on.
Referring to fig. 10, a battery charging path in a normal operation mode of a battery interface architecture diagram is provided, the battery interface includes a DC-DC converter, a first power switch tube S is connected to the battery sideb1The second power switch tube S at the battery sideb2Battery side inductor LbatThe first quick relay SR1And the second quick relay SR2And (4) forming. In normal operation mode, the battery is charged, the first rapid relay SR1Switched on, the second rapid relay SR2And when the direct current bus is disconnected, the rectification stage and the inversion stage normally operate, and in the mode, the battery is charged from the direct current bus through the DC-DC converter.
Referring to fig. 11, for the battery discharge path in the standby operation mode of the battery interface architecture diagram, when the grid fails, the DC-DC converter is not used to supply power to the load, in which case the first fast relay SR1Open, second fast relay SR2And when the input end of the boost converter is connected, the battery is connected to the input end of the boost converter, and the boost converter consists of a first power switch tube, a second power switch tube and an input inductor. The boost converter of the rectifier stage sets a rated value for the output power of the system, and transmits the power to the direct current bus, thereby ensuring that the power is continuously output to the load through the inverter stage.
Example 1
An AC-DC-AC converter for an online UPS includesAC input voltage source and first power switch tube S1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8The input inductor, the output inductor and the bus capacitor;
first end of AC input voltage source and third power switch tube S3Is connected with the second end of the AC input voltage source and the first power switch tube S1Second end of source and bus capacitor and sixth power switch tube S6The source electrodes of the first and second transistors are connected with the second end of the output end; third power switch tube S3Drain of and fourth power switch tube S4The source of the input inductor is connected with the first end of the input inductor; the second end of the input inductor and the second power switch tube S2Source electrode of (1) and first power switch tube S1The drain electrodes of the two transistors are connected; fourth power switch tube S4And a second power switch tube S2First end of drain electrode and bus capacitor and fifth power switch tube S5Drain electrode of and seventh power switch tube S7The drain electrodes of the two transistors are connected; fifth power switch tube S5Source and sixth power switch tube S6The drain electrode of the first switch is connected with the first end of the output inductor; seventh power switch tube S7Source electrode of and eighth power switch tube S8The drain electrode of the first diode is connected with the second end of the output inductor; eighth power switch tube S8Is connected to the first end of the output terminal.
The first power switch tube S1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8Are all SiCMOS switch tubes.
The first power switch tube S1A second power switch tube S2The third power switch tube S3Fourth power switch tube S4Fifth, thePower switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8Are provided with diodes connected in parallel.
The first power switch tube S1A second power switch tube S2Driven by complementary pulses.
The third power switch tube S3Fourth power switch tube S4Driven by complementary pulses.
The fifth power switch tube S5Sixth power switch tube S6Driven by complementary pulses.
The seventh power switch tube S7The eighth power switch tube S8Driven by complementary pulses.
The first power switch tube S1A second power switch tube S2The third power switch tube S3Fourth power switch tube S4Constituting the rectifier stage of the converter.
The first power switch tube S1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4Can realize the soft switch of zero voltage switching-on.
The fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7Forming an inverter stage of the transformer.
A control method for an AC-DC-AC converter of an on-line UPS is to operate the rectification stage of the converter in two operation modes of boost and buck-boost for rectification stage control, and to reduce the size of an input inductor, the converter is operated at a high frequency. In order to maintain high efficiency at high switching frequencies, the rectification stage operates in a Boundary Conduction Mode (BCM) to achieve Zero Voltage Switching (ZVS) of the power switching tube. During the positive half period of the input voltage, the rectification stage operates in boost mode, the instantaneous value of the input voltage is less than half the dc bus voltage, and when the instantaneous value of the input voltage is greater than half the dc bus voltage, only that is the caseThe inductor current at the end of each switching cycle being less than a negative value iboostminOnly then ZVS can be implemented; cOSSIs a first power switch tube S1And a second power switch tube S2The parasitic capacitance of (2); second power switch tube S2The first power switch tube S can be ensured to be switched on for a period of time after the zero crossing of the inductor current to establish the required negative inductor current1Zero voltage turn-on (ZVS); during the negative half-cycle of the input voltage, the rectifier stage operates in buck-boost mode, the third power switch S3And a fourth power switch tube S4Naturally realizing zero voltage switching-on (ZVS), and when the instantaneous value of the input voltage is less than the bus voltage, the third power switch tube S3And a fourth power switch tube S4The buck-boost converter is always operated in boost mode, in which the third power switch tube S3Does not need a fourth power switch tube S4Turned on for a period of time to achieve zero voltage turn-on (ZVS). In the control of the whole rectification stage, the rectification stage works in the BCM mode, and the first power switch tube S is controlled by sensing the polarity of the input voltage1A second power switch tube S2The third power switch tube S3Fourth power switch tube S4Generating a driving signal of a grid; for positive input voltage, the first power switch tube S1First turn on tonboostFor this long time, then the second power switch tube S2Is turned on until the inductor current drops to iboostminThe following; for negative input voltages, the third power switch S3First on tonbuck-boostFor this long time, then the fourth power switch S4Switching on until the inductor current reaches zero; a Zero Current Detection (ZCD) circuit is required in the overall control, which induces an inductor current and uses two hysteretic comparators, one for each half input cycle. For the positive half period of the input voltage, when the inductive current drops to iboostminThe hysteresis comparator generates a trigger signal, and similarly during the negative half cycle of the input voltage, when the inductor current reaches zero, the hysteresis trigger generates a trigger signal, and the controller detects each half cycleAn interim trigger signal to reset the PWM counter and start the next switching cycle; the output voltage of the rectifier stage is regulated by a low-bandwidth voltage loop of the PI controller to output a first power switch tube S1And a third power switch tube S3On-time of (d); for the control of the inversion stage, the inversion stage is mainly used for generating sinusoidal alternating-current voltage at the output end, and the inversion stage also works in two working modes of boost and buck-boost. The inverter stage operates in Continuous Conduction Mode (CCM) with a fixed switching frequency. In the whole inversion stage control, a voltage error signal is generated by comparing a sinusoidal reference voltage with a detected output voltage and is sent to a controller of an inversion stage, wherein the controller of the inversion stage comprises two controllers and GcbuckAnd Gcbuck-boost(ii) a For positive output voltage half-cycle, buck controller GcbuckA controller G for generating a buck-boost duty cyclecbuck-boostThe output of the eighth power switch tube is ignored, and the eighth power switch tube is kept on; for negative output voltage half-cycles, buck-boost controller Gcbuck-boostGenerating and controlling a seventh power switch tube S7Duty cycle of (3), buck controller GcbuckIs ignored, the sixth power switch tube S6Remain on.
Further, iboostminIs less than or equal to
Wherein CossIs the parasitic capacitance of the power switch tube.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (9)
1. The AC-DC-AC converter for online UPS includes AC input voltage source Vin, the first power switch tube S1A second power switch tube S2Third powerSwitch tube S3Fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8An input inductor LinAn output inductor LoutBus capacitor Cbus；
The first end of the AC input voltage source Vin and the third power switch tube S3Is connected with the second end of the AC input voltage source Vin and the first power switch tube S1Source electrode and bus capacitor CbusSecond terminal and sixth power switch tube S6The source electrodes of the first and second transistors are connected with the second end of the output end; third power switch tube S3And a fourth power switch tube S4Source and input inductance L ofinAre all connected; input inductance LinAnd a second terminal of the second power switch tube S2Source electrode and first power switch tube S1The drain electrodes of the two are all connected; fourth power switch tube S4And a second power switch tube S2Drain electrode and bus capacitor CbusAre all connected; fifth power switch tube S5Drain electrode of and seventh power switch tube S7Is connected with the drain electrode of the transistor; fifth power switch tube S5Source electrode of and sixth power switch tube S6Drain of and output inductor LoutIs connected with the first end of the first connecting pipe; seventh power switch tube S7Source electrode of and eighth power switch tube S8Drain of and output inductor LoutThe second ends of the two are connected; eighth power switch tube S8Is connected to the first end of the output terminal.
2. An AC-DC-AC converter for an online UPS as defined in claim 1 in which the first power switch S is a single transistor1A second power switch tube S2The third power switch tube S3Fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8Are all SiCMOS switch tubes.
3. An AC-DC-AC converter for an online UPS as defined in claim 1 in which the first power switch S is a single transistor1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8Are provided with diodes connected in parallel.
4. An AC-DC-AC converter for an online UPS as defined in claim 1 wherein the first power switch S1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7The eighth power switch tube S8Driven by complementary pulses.
5. An AC-DC-AC converter for an online UPS as defined in claim 1 wherein the first power switch S1A second power switch tube S2The third power switch tube S3Fourth power switch tube S4Constituting the rectifier stage of the converter.
6. An AC-DC-AC converter for an online UPS as defined in claim 1 in which the first power switch S is a single transistor1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4The soft switch can realize zero voltage switching.
7. An AC-DC-AC converter for an online UPS as defined in claim 1 in which the fourth power switch S4The fifth power switch tube S5Sixth power switch tube S6Seventh power switch tube S7Forming the inverter stage of the transformer.
8. A method of controlling an AC-DC-AC converter for an online UPS according to claim 1, comprising the steps of:
for the control of the rectification stage, the rectification stage of the converter works in two working modes of boost and buck-boost, and in order to reduce the size of input inductance, the converter operates at high frequency; in order to keep high efficiency under high switching frequency, the rectification stage works in a boundary conduction mode to operate, so that the power switching tube is switched on at zero voltage;
in the positive half period of the input voltage, the rectification stage operates in a boost mode, and the instantaneous value of the input voltage is less than half of the voltage of the direct current bus; when the instantaneous value of the input voltage is greater than half the dc bus voltage, only the inductor current at the end of each switching cycle is less than a negative value iboostminWhen the voltage is zero, zero voltage switching-on can be realized; cOSSIs a first power switch tube S1And a second power switch tube S2The parasitic capacitance of (2); second power switch tube S2The first power switch tube S can be ensured to be switched on for a period of time to establish the required negative inductive current after the inductive current is zero-crossed1Zero voltage of (2) is turned on;
during the negative half-cycle of the input voltage, the rectifier stage operates in buck-boost mode, the third power switch S3And a fourth power switch tube S4Naturally realizing zero voltage switching-on, and when the instantaneous value of the input voltage is less than the bus voltage, the third power switch tube S3And a fourth power switch tube S4The buck-boost converter is always operated in boost mode, and in the boost mode, the third power switch tube S3Does not need a fourth power switch tube S4Switching on for a period of time to achieve zero voltage turn-on;
in the control of the whole rectification stage, the rectification stage works in a boundary conduction mode, and the first power switch tube S is controlled by sensing the polarity of the input voltage1A second power switch tube S2The third power switch tube S3The fourth power switch tube S4A drive signal of the gate; when the input voltage is greater than zero, the first power switch tube S1First turn on tonboostThen the second power switch tube S2Is turned on until the inductor current drops to iboostminThe following; when the input voltage is less than zero, the third power switch tube S3First on tonbuck-boostThen the fourth power switch tube S4Switching on until the inductor current reaches zero; a zero current detection circuit is needed in the whole control, the zero current detection circuit induces an inductive current, and two hysteresis comparators are utilized, and each half input period corresponds to one hysteresis comparator; in the positive half period of the input voltage, the inductor current drops to iboostminWhen the inductive current reaches zero in the negative half cycle of the input voltage, the hysteresis trigger generates a trigger signal, and the controller resets the PWM counter and starts the next switching cycle by detecting the trigger signal in each half cycle; the output voltage of the rectifier stage is regulated by the low-bandwidth voltage loop of the PI controller to control the first power switch tube S1And a third power switch tube S3On-time of (d);
for the control of the inversion stage, the inversion stage is mainly used for generating sine alternating-current voltage of an output end, and the inversion stage also works in two working modes of boost and buck-boost; the inverter stage works in a continuous conduction mode with fixed switching frequency;
in the whole inversion stage control, a voltage error signal is generated by comparing a sinusoidal reference voltage with a detected output voltage and is sent to a controller of an inversion stage, wherein the controller of the inversion stage comprises two controllers GcbuckAnd Gcbuck-boost(ii) a When the output voltage is greater than zero, the controller G of buckcbuckControlling a fifth power switch transistor S5Duty cycle of (3), buck-boost controller Gcbuck-boostThe output of the eighth power switch tube is ignored, and the eighth power switch tube is kept on; when the output voltage is less than zero, buck-boost controller Gcbuck-boostController G for controlling duty ratio and buck of seventh power switch tubecbuckThe output of the sixth power switch tube is ignored, and the sixth power switch tube is kept on.
9. An AC-DC-AC converter and control strategy for an online UPS according to claim 8 where a single DC bus is used between the rectification and inverter stages.
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| CN118137857A (en) * | 2024-05-08 | 2024-06-04 | 甬江实验室 | Modulation method, modulation system, modulation equipment and modulation medium of converter |
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