CN107017697B - Three-arm rectifying inverter series load type UPS circuit and control method thereof - Google Patents
Three-arm rectifying inverter series load type UPS circuit and control method thereof Download PDFInfo
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- CN107017697B CN107017697B CN201710208414.7A CN201710208414A CN107017697B CN 107017697 B CN107017697 B CN 107017697B CN 201710208414 A CN201710208414 A CN 201710208414A CN 107017697 B CN107017697 B CN 107017697B
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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
- H02J9/061—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 for DC powered loads
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
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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
- H02M5/4585—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 having a rectifier with controlled elements
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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
- H02J9/068—Electronic means for switching from one power supply to another power supply, e.g. to avoid parallel connection
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- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
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Abstract
The invention discloses a series load type UPS circuit of a three-arm rectification inverter and a control method thereof, wherein the circuit comprises a charger, a battery, a DC-DC converter, a synchronous Switch (SW), a rectification inverter, a mains voltage detector and a controller, wherein the charger is connected with a mains in series; when the commercial power is normal, the rectifier inverter acts, and the commercial power current passes through the synchronous switch, the load, the inverter arm and the common arm to form a loop; when the mains supply is interrupted, the inverting arm of the rectifying arm acts, and the battery current passes through the DC-DC converter, the inverting arm and the rectifying arm and then returns to the DC-DC converter to form a loop; the circuit and the method have the advantages that the inverter arm only processes a small part of load voltage, and the rectifier arm only flows reactive power and harmonic current of the load, so that the efficiency is higher under most working conditions, and the distortion and reactive power components of the load current can be compensated to improve the input power factor.
Description
Technical Field
The present invention relates to a UPS circuit, and more particularly, to a UPS circuit having a three-arm rectifier inverter connected in series with a load and a control method thereof.
Background
A conventional on-line UPS (on-line UPS) circuit architecture is shown in fig. 1, and includes a Rectifier (Rectifier) -Inverter (Inverter), a Charger (Charger), and a DC-to-DC (DC/DC) converter. In normal mains, load power is supplied via the mains-rectifier-dc-link-inverter path, and in the event of mains outage, load power is supplied by the battery-dc-to-dc converter-dc-link-inverter path. The two-stage power conversion circuit has the advantages of being capable of simultaneously performing input Power Factor Control (PFC) and adjusting load voltage, and has the defect that the overall efficiency is equal to the product of the efficiency of a rectifier and the efficiency of an inverter, so that the overall efficiency is low.
Disclosure of Invention
The present invention is to solve the above problems in the prior art, and provides a load-type UPS circuit with a series connection of three-arm rectifier inverters, which has high efficiency and can improve the input power factor, and a control method thereof.
In order to solve the technical problem, the invention provides a technical scheme that a three-arm rectification inverter series load type UPS circuit is designed, and the three-arm rectification inverter series load type UPS circuit comprises a charger, a battery and a DC-DC converter, wherein the charger, the battery and the DC-DC converter are connected with a mains supply in series; the system comprises a main power supply, a controller, a synchronous switch, a rectification inverter, a mains voltage detector and a controller, wherein the synchronous switch, the rectification inverter, the mains voltage detector and the controller are sequentially connected and then connected to mains supply, the mains voltage detector is used for detecting whether the mains supply is interrupted, the controller is used for receiving signals detected by the mains voltage detector, the rectification inverter comprises a rectification arm, a common arm and an inversion arm which are connected in parallel, the rectification arm comprises two power switches which are connected in series, and a connecting point C of the two power switches is in coupling connection with the synchronous switch and a load; the common arm comprises two power switches connected in series, and the connection point A of the two power switches is connected with the ground of the commercial power; the inversion arm comprises two power switches connected in series, and the connection point B of the two power switches is coupled and connected with the other end of the load; two output ends of the DC-DC converter are respectively connected with two ends of the rectifying arm, the common arm and the inverting arm which are connected in parallel; the controller controls the rectifying inverter to act when the mains supply is normal, and mains supply current passes through the synchronous switch, the load, the inverting arm and the common arm to form a loop; the controller controls the inversion arm of the rectification arm to act when the mains supply is interrupted, and the battery current returns to the DC-DC converter through the DC-DC converter, the inversion arm and the rectification arm to form a loop. And a filter capacitor is connected between the two ends of the parallel rectification arm, the common arm and the inversion arm. And two ends of the load are respectively connected with the reactors in series. The controller adopts an SPWM controller, and SPWM signals are used for controlling power switches in the rectifying arm, the common arm and the inverting arm. The DC-DC converter adopts a current source push-pull converter with a buck-boost characteristic.
The invention also provides a control method of the three-arm rectification inverter series load type UPS circuit, which comprises the following steps: detecting whether the commercial power is normal by using a commercial power voltage detector, receiving a signal detected by the commercial power voltage detector by using a controller, and controlling a rectifying inverter to act according to the signal, wherein the rectifying inverter comprises a rectifying arm, a common arm and an inverting arm which are connected in parallel; the rectification arm is formed by two power switches connected in series, and the connecting point C of the two power switches is connected with the synchronous switch and the load in a coupling mode; two power switches connected in series form the common arm, and a connection point A of the two power switches is connected with the ground of the commercial power; the inverter arm is formed by two power switches connected in series, and a connection point B of the two power switches is coupled and connected with the other end of the load; when the commercial power is normal, the synchronous switch is turned on, the rectifier inverter acts, and the commercial power current passes through the synchronous switch, the load, the inverter arm and the common arm to form a loop; when the commercial power is interrupted, the DC-DC converter performs power conversion, the inverting arm of the rectifying arm acts, and the battery current returns to the DC-DC converter through the DC-DC converter, the inverting arm and the rectifying arm to form a loop. And a filter capacitor is connected between the two ends of the parallel rectification arm, the common arm and the inversion arm. And two ends of the load are respectively connected with the reactors in series. The controller adopts an SPWM controller, and SPWM signals are used for controlling power switches in the rectifying arm, the common arm and the inverting arm. The DC-DC converter adopts a current source push-pull converter with a buck-boost characteristic.
Compared with the prior art, the circuit and the method have the advantages that the inverter arm only processes a small part of load voltage, and the rectifier arm only flows reactive power and harmonic current of the load, so that the efficiency is higher under most working conditions, and the distortion and reactive power components of the load current can be compensated to improve the input power factor.
Drawings
FIG. 1 illustrates a conventional dual stage online UPS circuit architecture;
FIG. 2 is a schematic block diagram of an online series voltage regulation;
FIG. 3 is a half-bridge rectifier-inverter architecture;
FIG. 4 is a rectifier-inverter architecture with a bridgeless architecture for the rectifier;
FIG. 5 illustrates a three-arm cascaded rectifier-inverter circuit architecture;
FIG. 6 is a UPS circuit architecture employing a three-arm series rectifier inverter;
FIG. 7 illustrates a control signal architecture for a UPS;
FIG. 8 is a rectified partial phasor diagram;
FIG. 9 is a phasor diagram for the inverting portion (buck mode);
FIG. 10 is a phasor diagram for the inverting portion (boost mode);
FIG. 11 is a control block diagram of the rectifying portion of the series architecture with PWM switching of the middle arm;
FIG. 12 is a block diagram of the control of the inverter portion of the cascaded configuration with PWM switching of the middle arm;
FIG. 13 is a simulation circuit diagram;
FIG. 14 is a response waveform at a resistive load varying from 500W to 1 kW;
FIG. 15 is a waveform of a response under an R-C-D load (80. Omega. + 330. Mu.F).
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention discloses a series load type UPS circuit of a three-arm rectification inverter, which comprises a charger, a battery and a DC-DC converter, wherein the charger, the battery and the DC-DC converter are connected with a mains supply in series; the system also comprises a synchronous switch, a rectification inverter, a mains voltage detector (not shown in figure 2) and a controller (not shown in figure 2), wherein the synchronous switch, the rectification inverter, the mains voltage detector and the controller are sequentially connected and then connected to the mains, the mains voltage detector is used for detecting whether the mains is interrupted, and the controller is used for receiving signals detected by the mains voltage detector. To illustrate the working principle, refer to the schematic block diagram shown in fig. 2. The scheme adopts a mode of adjusting the power factor and the load voltage on line, the inverter adopts a framework which is connected in series with the mains supply voltage, the load power is directly provided by the mains supply series inverter under the normal mains supply, and the inverter adjusts the load voltage by compensating the mains supply voltage change and the distortion mode at the moment. In a voltage reduction mode (the mains voltage is higher than the output voltage), the inverter absorbs active power, and the active power is recycled to the mains input side by a rectifier connected with the mains in parallel; whereas in boost mode (mains voltage lower than the output voltage) the inverter needs to provide active power, which is absorbed by the rectifier from the mains input. The rectifier also acts as an active power filter to compensate for distortion and reactive components of the load current to improve the power factor of the input. In this way, although the rectifier-inverter is still in two stages, the rectifier and inverter only process a small part of the load power, so the loss is small and the overall efficiency is high. When the commercial power is interrupted, the synchronous switch SW is turned off, and the two output terminals B and C of the rectifier and the inverter form the inverter for providing the load voltage and the storage battery provides uninterrupted power through the DC-DC converter.
In the preferred embodiment, the rectifier and inverter of fig. 2 are integrated as a rectifier inverter, and the most commonly adopted circuit architecture for the rectifier inverter circuit of the UPS circuit is a half-bridge type current transformer-inverter architecture as shown in fig. 3, for a 230Vac system, the dc link voltage is raised to 800V, and for a load with asymmetric positive and negative half cycle currents, an imbalance of the voltage divider capacitor may be caused. Another structure is shown in fig. 4, the rectifier adopts a rectifier-inverter structure without a bridge structure, the voltage-doubling rectification mode has a voltage boosting ratio only half that of fig. 3, and in addition, the diode of the a-arm can be a faster diode, so as to achieve the purposes of higher-speed switching and low conduction voltage drop. The structures of fig. 3 and 4 are also in a half-bridge type structure in the inverter portion, so that the problems of high on-current and capacitor voltage balance still exist. To solve this problem and improve the efficiency of the above-mentioned mains-to-load power supply and reduce the cost of the converter, the preferred embodiment of the present invention is shown in fig. 5: the rectifying inverter comprises a rectifying arm, a common arm and an inverting arm which are connected in parallel, wherein the rectifying arm comprises two power switches which are connected in series, and a connecting point C of the two power switches is connected with the synchronous switch and a load in a coupling mode; the common arm comprises two power switches connected in series, and the connection point A of the two power switches is connected with the ground of the commercial power; the inversion arm comprises two power switches connected in series, and the connection point B of the two power switches is coupled and connected with the other end of the load; two output ends of the DC-DC converter are respectively connected with two ends of the parallel rectification arm, the common arm and the inversion arm. The rectifier inverter is of a three-arm series connection type structure, maintains a direct current voltage (Vd) by using a rectifier arm (REC-arm), and simultaneously maintains the direct current voltage (Vd)The active filter compensates the reactive and harmonic currents of the load so that the input current of the utility power is low distortion and unity power factor. Using the output voltage (Vo) of the inverter arm (INV-arm) and the load voltage (V) L ) Connected in series, with the series voltage of both being equal to the mains voltage (Vs), so that the inverter only processes the difference between the mains voltage and the load voltage.
V s ＝V o +V L (1)
And secondly, because the sum of the three-arm current is zero, the intermediate arm (COM-arm) flows through the difference value of the currents of the rectifier arm (REC-arm) and the inverter arm (INV-arm), and the intermediate arm current is equal to the active current of the load under the unit power factor.
Fig. 6 shows a UPS circuit architecture using a three-arm series-connected rectifier-inverter, where a mains voltage detector (grid voltage detection) detects whether a mains voltage is normal, and if the mains voltage is normal, the UPS circuit operates in an on-line mode, load power is provided by the mains, the controller controls the three-arm rectifier-inverter to operate, a loop is formed from a mains current passing through a synchronous switch, a load, an inverter arm, and a common arm, the rectifier arm is responsible for adjusting a power factor input by the mains and adjusting a 400V dc link voltage, and the inverter arm is responsible for adjusting the load voltage. If the commercial power is in a fault, the system is operated in a discharge mode (discharge mode), load power is provided by a battery, the converter is used for controlling the battery to discharge and raising the battery voltage to 400V, the controller is only used for controlling a rectifying arm and an inverting arm in the three-arm rectifying inverter to act and is used for adjusting the load voltage, the middle arm stops switching, and the battery current passes through the DC-DC converter, the inverting arm and the rectifying arm and then returns to the DC-DC converter to form a loop. Therefore, whether the commercial power is normal or not, uninterrupted power supply to the load is guaranteed.
Referring to fig. 6, in the preferred embodiment, a filter capacitor is connected between two ends of the parallel rectification arm, the common arm and the inversion arm. And two ends of the load are respectively connected with the reactors in series. The DC-DC converter adopts a current source push-pull converter with a buck-boost characteristic. The DC-DC converter adopts a current-fed push-pull converter (current-fed push-pull converter) with a voltage boosting and reducing characteristic, so that the system has a wider input battery voltage range to increase the discharge time and reduce the AH capacity of the battery, and the DC-DC converter can also adopt other circuits to be matched with the series-connection three-arm rectifier-inverter.
Fig. 7 shows a control signal architecture diagram of a UPS that employs an SPWM controller and controls power switches in the rectifying, common, and inverting arms with SPWM signals. A bypass switch (bypass SW) is provided between the mains voltage and the load for directly supplying the load with the mains voltage during maintenance.
As can be derived from the three-arm rectifier-inverter circuit of fig. 6:
the three arms all adopt sinusoidal PWM switching, and the output voltages of the three arms can be respectively expressed as:
substituting (4) into (2) and (3) again can obtain:
(5) And (6) the outputs of the rectifying arm and the inverting arm are both affected by the common arm, and if the switching of the rectifying arm and the inverting arm is not required to generate interaction, the (5) and (6) must be decoupled. Considering that the series configuration Vo can be in-phase (buck mode) or in-phase (boost mode) with Vs, the present inventor proposes the setting of the middle arm control voltage:
substituting (7) into (5) and (6) can obtain:
from (8) and (9), the phasor diagram of FIG. 7 can be obtained, allowing for both buck and boost mode operation, as can be seen from the phasor diagrams of FIGS. 8 and 9, since k is pwm v conC And k pwm v conB Respectively, may be greater than V L /2-V s And 3V L /2-V s So that the PWM switching of the rectifying arm and the inverting arm can also be in the linear region and the DC voltage (V) d ) As determined by the boosting mode of fig. 10, the following conditions must be satisfied:
V d >3V L(peak,max) -2V s(peak,min) (10)
since the size of the general VL is set close to Vs, (10) indicates the direct current voltage (V) of the present creation d ) It only needs to be larger than one time of the mains voltage (i.e. 230Vac system, 400V).
Fig. 7 is a series circuit phasor diagram with PWM switching in the middle arm: FIG. 8 a rectifying portion; FIG. 9 inverting portion (buck mode); fig. 10 inverter portion (boost mode).
The controller can be designed according to the circuit models (8) and (9) derived as described above, and fig. 11 and 12 are block diagrams of control loops of the rectifying arm and the inverting arm, respectively, in which the power circuit portion is drawn according to the circuit models (8) and (9), k s And k v The sensing ratios of the current and voltage are provided. The control of the rectifier arm comprises a voltage control loop and a current control loop, the current control loop adopts forward (fed forward) and feedback control for use, and a forward control signal v fi Using normal value (v) of input voltage m sin ω t) and command of load voltage
Direct elimination of V s And V L Such as current feedback controller k 1 Only one ratio (P) control may be used. However, in order to compensate for the reactive power and harmonic current of the load to perform the function of the active power filter, the feedback current is the input current rather than the current of the rectifying arm. This has the advantage that only one current sensor is used. If the disturbance of the load current is ignored, the response of the input current to track its command can be inferred from fig. 8 as:
inputting a current command
Is generated by a DC voltage loop, a DC voltage controller G v Generating an amplitude of an input current command based on a DC voltage error>
Which is inverted and multiplied by the synchronization signal (sin ω t) to obtain the current command ≥ of the rectifier>
The DC voltage inevitably will contain secondary ripple (2 f) o )，G v The controller is designed to make the bandwidth of the voltage loop much lower than the secondary frequency to attenuate the secondary ripple component so that the mains current has low distortion.
For the control of the inverter arm, the output capacitor voltage from fig. 6 can be derived:
FIG. 12 is a block diagram of an inverter arm control loop with dual loop controlThe loop is a voltage loop, and the inner loop is a capacitance current loop. However, since the capacitance current is a differential of the voltage, the capacitance current can be estimated by using the voltage, thereby saving a current sensor. The dashed portion of FIG. 12 is the virtual capacitor current feedback (i) cap ) Which is only used for analysis, is carried out using estimation
And (4) substitution. Considering that the differentiation is also disturbed by noise, the inventive differentiator is in the form of a block diagram additionally incorporating a low pass filter 1/(1 + τ s) for approximating a differentiator at low frequencies and attenuating the gain at high frequencies. The current control loop preferably still adds a forward control signal v fI For eliminating V L And V s The disturbance of (2). The response of the current loop can be roughly estimated using a virtual current sensing loop as:
u I which can be considered as the bandwidth of the current loop. The command of the capacitor current may be commanded by a voltage
Through a 90 ° phase shift circuit, however, to overcome the error of the current loop, the error of the voltage and its command must be added.
In order to verify the feasibility of the circuit and the control method, the present inventor actually designs a 1KVA/230V/50Hz system and verifies it by simulation, the circuit parameters are as follows:
v tm ＝5V/20KHz,V s ＝230Vrms±10％,k s ＝0.1,k v ＝0.01,
C d ＝1000μF,L＝1mH,C o ＝10μF
simulation Circuit As shown in FIG. 13, the response waveform when the resistive load is changed from 500W to 1kW is shown in FIG. 14, and is measured by the input current (I) s ) Closely track its commands (I) sc ) Can also verify the validity of the current controller. The DC voltage can be maintained at 400V accurately, and has good dynamic response, the effectiveness of the DC voltage control loop is verified, and the output voltage (V) is obtained L ) Can closely follow the command (V) LC ) And the effect of low output impedance is achieved. The response under the rectifying R-C-D load (80 Ω +330 μ F) is as shown in fig. 15, although the load current is severely distorted, the input current is compensated by the rectifying arm current to be quite nearly sinusoidal and in phase with the input voltage, and it is verified that the rectifying arm has the function of an active filter. The above simulation results not only verify the effectiveness of the proposed control method, but also indirectly verify the accuracy of the proposed switching method and derivation model of the middle arm, and prove that the proposed three-arm series rectifier-inverter is really feasible for application in UPS.
The invention also discloses a control method of the three-arm rectifier inverter series load type UPS circuit, which comprises the steps that a commercial power voltage detector is used for detecting whether commercial power is normal, a controller receives a signal detected by the commercial power voltage detector and controls the action of the rectifier inverter according to the signal, and the rectifier inverter comprises a rectifier arm, a common arm and an inverter arm which are connected in parallel with each other with reference to fig. 6 or fig. 7; the rectification arm is formed by two power switches connected in series, and the connecting point C of the two power switches is connected with the synchronous switch and the load in a coupling mode; two power switches connected in series form the common arm, and a connection point A of the two power switches is connected with the ground of the commercial power; the inverter arm is formed by two power switches connected in series, and a connection point B of the two power switches is coupled and connected with the other end of the load; when the commercial power is normal, the synchronous switch SW is turned on, the rectifier inverter acts, and the commercial power current passes through the synchronous switch, the load, the inverter arm and the common arm to form a loop; when the commercial power is interrupted, the DC-DC converter performs power conversion, the inverting arm of the rectifying arm acts, and the battery current returns to the DC-DC converter through the DC-DC converter, the inverting arm and the rectifying arm to form a loop.
The control method provided by the invention is suitable for a three-arm type rectifying inverter circuit structure of an online UPS, three switch arms (a rectifying arm, a common arm and an inverting arm) are switched by sine PWM, wherein the load voltage is adjusted by the inverting arm connected in series with the load voltage, the rectifying arm is used as an active filter to adjust the power factor of commercial power input and adjust 400V direct-current link voltage, and the switching of the middle arm is not required to be controlled and only adopts a default voltage command. Compared with the traditional two-stage rectifier-inverter circuit architecture, the circuit has the advantages that the inverter arm only processes a small part of load voltage, and the rectifier arm only flows reactive power and harmonic current of the load, so that the efficiency is higher under most working conditions.
Referring to the preferred embodiment shown in fig. 5 and 6, a filter capacitor Cd is connected between two ends of the parallel rectification arm, the common arm and the inversion arm.
Referring to the preferred embodiment shown in fig. 5 and 6, the two ends of the load are respectively connected with the reactors L in series.
In a preferred embodiment, the controller adopts an SPWM controller, and SPWM signals are used for controlling power switches in the rectifying arm, the common arm and the inverting arm.
Referring to the preferred embodiment shown in fig. 6, the DC-DC converter employs a current source push-pull converter with a buck-boost characteristic.
The foregoing examples are illustrative only and are not intended to be limiting. Any equivalent modifications or variations without departing from the spirit and scope of the present application should be included in the claims of the present application.
Claims (10)
1. A three-arm rectifier inverter series load type UPS circuit comprises a charger, a battery and a DC-DC converter, wherein the charger, the battery and the DC-DC converter are connected with a mains supply in series, and the three-arm rectifier inverter series load type UPS circuit is characterized in that: the system also comprises a synchronous Switch (SW) connected with the mains supply in sequence, a rectifier inverter, a mains supply voltage detector for detecting whether the mains supply is interrupted, and a controller for receiving signals detected by the mains supply voltage detector, wherein the rectifier inverter comprises a rectifier arm, a common arm and an inverter arm which are connected in parallel, and the rectifier inverter comprises a rectifier arm, a common arm and an inverter arm which are connected in parallel
The rectifying arm comprises two power switches connected in series, and a connecting point (C) of the two power switches is coupled with the synchronous switch and the load;
the common arm comprises two power switches connected in series, and the connection point (A) of the two power switches is connected with the ground of the commercial power;
the inversion arm comprises two power switches connected in series, and the connection point (B) of the two power switches is coupled and connected with the other end of the load;
two output ends of the DC-DC converter are respectively connected with two ends of the rectifying arm, the common arm and the inverting arm which are connected in parallel;
the controller controls the rectifying inverter to act when the mains supply is normal, and mains supply current passes through the synchronous switch, the load, the inverting arm and the common arm to form a loop;
the controller controls the action of the inverting arm of the rectifying arm when the mains supply is interrupted, and the battery current returns to the DC-DC converter through the DC-DC converter, the inverting arm and the rectifying arm to form a loop.
2. The three-leg commutated inverter series-connected load type UPS circuit of claim 1, wherein: and a filter capacitor (Cd) is connected between two ends of the parallel rectification arm, the common arm and the inversion arm.
3. The three-leg commutated inverter series-connected load type UPS circuit of claim 2, wherein: and two ends of the load are respectively connected with the electric reactor (L) in series.
4. The three-leg commutated inverter series-connected load type UPS circuit of claim 3, wherein: the controller adopts an SPWM controller, and SPWM signals are used for controlling power switches in the rectifying arm, the common arm and the inverting arm.
5. The three-leg commutated inverter series-connected load type UPS circuit of claim 4, wherein: the DC-DC converter adopts a current source push-pull converter with a buck-boost characteristic.
6. A control method for a three-arm rectification inverter series load type UPS circuit is characterized in that: detecting whether the commercial power is normal by using a commercial power voltage detector, receiving a signal detected by the commercial power voltage detector by using a controller, and controlling a rectifying inverter to act according to the signal, wherein the rectifying inverter comprises a rectifying arm, a common arm and an inverting arm which are connected in parallel; the rectification arm is formed by two power switches connected in series, and a connecting point (C) of the two power switches is coupled with the synchronous switch and the load; two power switches connected in series form the common arm, and a connection point (A) of the two power switches is connected with the ground of the commercial power; the inverter arm is formed by two power switches connected in series, and a connection point (B) of the two power switches is coupled and connected with the other end of the load;
when the commercial power is normal, a synchronous Switch (SW) is turned on, the rectifier inverter acts, and the commercial power current passes through the synchronous switch, the load, the inverter arm and the common arm to form a loop;
when the mains supply is interrupted, the DC-DC converter performs power conversion, the rectifying arm acts, and the battery current returns to the DC-DC converter through the DC-DC converter, the inverting arm and the rectifying arm to form a loop.
7. The method of claim 6, wherein the step of controlling the three-leg commutated inverter-series-connected load-type UPS circuit comprises the steps of: and a filter capacitor (Cd) is connected between the two ends of the parallel rectifying arm, the common arm and the inverting arm.
8. The method of claim 7, wherein the step of controlling the three-leg commutated inverter-series load type UPS circuit further comprises the steps of: and two ends of the load are respectively connected with the electric reactor (L) in series.
9. The method of claim 8, wherein the step of controlling the three-leg commutated inverter-series load UPS circuit comprises: the controller adopts an SPWM controller, and SPWM signals are used for controlling power switches in the rectifying arm, the common arm and the inverting arm.
10. The method of claim 9, wherein the step of controlling the three-leg commutated inverter-series load UPS circuit comprises: the DC-DC converter adopts a current source push-pull converter with a buck-boost characteristic.
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| CN102201739A (en) * | 2011-05-27 | 2011-09-28 | 华北电力大学（保定） | Symmetrical half-bridge LLC resonant bidirectional DC-DC converter |
| CN202663185U (en) * | 2012-07-09 | 2013-01-09 | 佛山市柏克新能科技股份有限公司 | Series-parallel UPS (Uninterrupted Power Supply) with single inverter |
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| CN102901919B (en) * | 2011-07-29 | 2015-02-04 | 台达电子企业管理（上海）有限公司 | Double-feedback type induction generating system and self-testing method of active crowbar circuit thereof |
| JP5476400B2 (en) * | 2012-01-30 | 2014-04-23 | 株式会社日立製作所 | Power conversion device, power conversion device control method, and hard disk device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102201739A (en) * | 2011-05-27 | 2011-09-28 | 华北电力大学（保定） | Symmetrical half-bridge LLC resonant bidirectional DC-DC converter |
| CN202663185U (en) * | 2012-07-09 | 2013-01-09 | 佛山市柏克新能科技股份有限公司 | Series-parallel UPS (Uninterrupted Power Supply) with single inverter |
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