CN107681912A - The equalizer circuit and its method for equalizing voltage of a kind of five-level converter - Google Patents

The equalizer circuit and its method for equalizing voltage of a kind of five-level converter Download PDF

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Publication number
CN107681912A
CN107681912A CN201711040995.4A CN201711040995A CN107681912A CN 107681912 A CN107681912 A CN 107681912A CN 201711040995 A CN201711040995 A CN 201711040995A CN 107681912 A CN107681912 A CN 107681912A
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China
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electric capacity
voltage
switching device
diode
inductance
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CN201711040995.4A
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CN107681912B (en
Inventor
舒泽亮
李祖勇
毛文君
姚家煊
孟令辉
何晓琼
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Southwest Jiaotong University
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Southwest Jiaotong University
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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
    • H02M7/42—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
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/487—Neutral point clamped inverters
    • 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
    • H02M7/5387—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 in a bridge configuration
    • H02M7/53871—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 in a bridge configuration with automatic control of output voltage or current

Abstract

The invention provides a kind of equalizer circuit of five-level converter and its method for equalizing voltage, it is related to electric and electronic technical field.Four electric capacity in DC capacitor group II are composed in series electric capacity pair respectively, aid in five switching devices in equalizer circuit I to be composed in series switch pair respectively；Equalizing capacitance CAS positive termination includes the switch of switching device A2 compositions between, and equalizing capacitance CAS negative terminal access includes the switch of switching device A4 compositions between；Electric capacity CA1 anode is connected with switching device A1 one end, and negative terminal is connected with the switching device A1 other end；Electric capacity CA4 negative terminal is connected with switching device A6 one end, and anode is connected with the switching device A6 other end；One end of switch pair including switching device A2 is connected with equal voltage inductance LA1, and the other end is connected with electric capacity CA2 negative terminal；One end of the switch pair of switching device A4 and switching device A5 compositions is connected with equal voltage inductance LA2, and the other end is connected with electric capacity CA3 anode；The midpoint of two switches pair picks out to be connected with equalizing capacitance CAS both ends.

Description

The equalizer circuit and its method for equalizing voltage of a kind of five-level converter
Technical field
The present invention relates to electric and electronic technical field, belongs to electric control appliance.
Background technology
Diode-clamped five-level converter is connected on DC side both ends using the DC capacitor of 4 series connection, meanwhile, conversion Multiple series switching devices of each bridge arm of device are connected on each DC capacitor by diode, i.e., will be switched by diode DC bus-bar voltage is divided into 5 level by the voltage clamp of device on a DC capacitor voltage of connection.Therefore, each The multiple switch device of bridge arm can export the voltage signal of varying level under different switch combinations to AC.By various PWM (Pulse Width Modulation, pulsewidth modulation) modulator approach, diode-clamped five-level converter is by 5 electricity Flat output signal synthesizes modulated signal, and level number is more, and the alternating voltage of converter output more approaches modulated signal.
But in diode clamped five-level converter, unequal power will be exported on each capacitor to be caused Voltage on capacitor is unequal, that is, so-called capacitance voltage imbalance problem occurs.By the PWM method of optimization, directly Stream electric capacity can realize the balance of voltage under certain condition and stably, the condition of its balance and stability and the phase angle of load current have Close.When five-level converter transmits pure watt current, i.e., when load current angle is near 0 degree, to ensure that DC voltage is steady It is fixed, it is desirable to PWM depth highest and to require to be less than about 55%, greatly limit diode-clamped circuit and transmit neck active The application in domain.After DC voltage unstability, multi-level converter will be degenerated to two level converters, while lose more level and had Plurality of advantages, or even influence converter inherently safe.
The content of the invention
First purpose of the present invention is just to provide a kind of equalizer circuit of five-level converter, and it can be efficiently solved Under any power factor condition, particularly when transmitting watt current, realize that the voltage of DC capacitor presses the technology with voltage stabilizing Problem.
It is a further object to provide a kind of method for equalizing voltage of five-level converter, and it can efficiently solve conversion The technical problem that the PWM depth of device is no longer limited by DC voltage stability condition, so as to realize that how electric diode-clamped is Flat converter DC capacitor voltage equilibrium with stably.
The present invention realizes its first goal of the invention, and used technical scheme is：
A kind of five-level converter DC capacitor equalizer circuit, including five-level converter III, the and of direct current capacitors group II Auxiliary equalizer circuit I is formed, and the input of five-level converter III is connected with the output of direct current capacitors group II, in DC capacitor group II Electric capacity CA1, electric capacity CA2, electric capacity CA3, electric capacity CA4One group of electric capacity pair is composed in series respectively, aids in the switch in equalizer circuit I Device A2, switching device A3With switching device A4, switching device A5One group of switch pair is composed in series respectively；Aid in equalizer circuit I by Equalizing capacitance CAS, equal voltage inductance LA1, equal voltage inductance LA2With switch to forming；Equalizing capacitance CAS positive termination switching device A2、 Switching device A3For the switch of composition between, equalizing capacitance CAS negative terminal meets switching device A4, switching device A5The switch of composition To between；Electric capacity CA1Anode and switching device A1One end be connected, negative terminal passes through equal voltage inductance LA1With switching device A1It is another One end is connected；Electric capacity CA4Negative terminal and switching device A6One end be connected, anode passes through equal voltage inductance LA2With switching device A6's The other end is connected；Switching device A2With switching device A3One end of switch pair and equal voltage inductance LA1It is connected, the other end and electric capacity CA2 Negative terminal be connected；Switching device A4With switching device A5One end of switch pair and equal voltage inductance LA2It is connected, the other end and electric capacity CA3 Anode be connected；The midpoint of two switches pair picks out to be connected with equalizing capacitance CAS both ends.
Second object of the present invention is to provide a kind of method for equalizing voltage of five-level converter, and way is：Control device leads to Cross controlling switch device A1, switching device A2, switching device A3, switching device A4, switching device A5With switching device A6It is open-minded Or shut-off so that the equal voltage inductance LA in each pulse width modulation cycle1, equal voltage inductance LA2With equalizing capacitance CAS according to upper and lower bridge The magnitude of voltage situation of electric capacity in arm between the magnitude of voltage of electric capacity or upper and lower bridge arm respectively with electric capacity CA1, electric capacity CA2, electric capacity CA3 With electric capacity CA4Connection, realize the pressure of each electric capacity；Electric capacity CA in i.e. upper bridge arm1Voltage is high, and electric capacity CA2When voltage is low, pass through Switching tube SA1, equal voltage inductance LA1Series connection forms electric capacity CA1Discharge loop (1), reduce electric capacity CA1Voltage, pass through equal piezoelectricity Feel LA1, diode DA2, diode DA3Series connection forms electric capacity CA2Charge circuit (2), increase electric capacity CA2Voltage；Instantly bridge Electric capacity CA in arm3Voltage height, and electric capacity CA4When voltage is low, pass through switching tube SA4, switching tube SA5, equal voltage inductance LA2Series connection shape Into electric capacity CA3Discharge loop (3), reduce electric capacity CA3Voltage, pass through equal voltage inductance LA2, diode DA6Series connection forms electricity Hold CA4Charge circuit (4), increase electric capacity CA4Voltage；As electric capacity CA in upper bridge arm1Voltage is low, and electric capacity CA2Voltage is high When, pass through diode DA1, equal voltage inductance LA1Series connection forms electric capacity CA1Charge circuit (5), increase electric capacity CA1Voltage, lead to Cross equal voltage inductance LA1, switching tube SA2, switching tube SA3Series connection forms electric capacity CA2Discharge loop (6), reduce electric capacity CA2Electricity Pressure；Instantly electric capacity CA in bridge arm3Voltage is low, and electric capacity CA4When voltage is high, pass through diode DA4, diode DA5, equal voltage inductance LA2Series connection forms electric capacity CA3Charge circuit (7), increase electric capacity CA3Voltage, pass through equal voltage inductance LA2, switching tube SA6Series connection Form electric capacity CA4Discharge loop (8), reduce electric capacity CA4Voltage；When upper bridge arm voltage is high, pass through switching tube SA1, switch Pipe SA2, equalizing capacitance CAS, diode DA4Series connection forms electric capacity CA1With electric capacity CA2Discharge loop (9), reduce electric capacity CA1With Electric capacity CA2Voltage, pass through switching tube SA3, equalizing capacitance CAS, diode DA5, diode DA6Series connection forms electric capacity CA3And electricity Hold CA4Charge circuit (10), increase electric capacity CA3With electric capacity CA4Voltage；Instantly when bridge arm voltage is high, diode DA is passed through1、 Diode DA2, equalizing capacitance CAS, switching tube SA4Series connection forms electric capacity CA1With electric capacity CA2Charge circuit (11), increase electric capacity CA1With electric capacity CA2Voltage, pass through diode DA3, equalizing capacitance CAS, switching tube SA5, switching tube SA6Series connection forms electric capacity CA3 With electric capacity CA4Discharge loop (12), reduce electric capacity CA3With electric capacity CA4Voltage.
It is above-mentioned to realize its second goal of the invention specific practice for the present invention：Described control device passes through controlling switch device Part A1, switching device A2, switching device A3, switching device A4, switching device A5With switching device A6Be switched on or off so that Voltage inductance LA in each pulse width modulation cycle1, equal voltage inductance LA2Electricity with equalizing capacitance CAS according to electric capacity in upper and lower bridge arm The magnitude of voltage situation of electric capacity between pressure value or upper and lower bridge arm respectively with electric capacity CA1, electric capacity CA2, electric capacity CA3With electric capacity CA4Even It is logical, realize the pressure of each electric capacity.
The present invention concrete operating principle be：Control device is by controlling opening for each auxiliary switch device in equalizer switch group Logical or shut-off so that each pulsewidth modulation (PWM) in the cycle equal voltage inductance or equalizing capacitance divide situation and each DC capacitor Connection side by side.When each DC capacitor connects side by side with equal voltage inductance or equalizing capacitance, the voltage of the two is carried out convergent Once equal press operation；One equal voltage inductance of complete PWM cycle or equalizing capacitance complete once pressure behaviour with whole DC capacitors Make.After multiple PWM cycles, the voltage of whole DC capacitors will reach unanimity, so as to realize the purpose pressed.
Compared with prior art, the beneficial effects of the invention are as follows：
First, pressure and the voltage stabilizing of main circuit DC capacitor are realized by the equalizer circuit set up, therefore is adjusted with the PWM of main circuit Method and control method processed are unrelated, do not influence existing main circuit and control principle, can be used for diode-clamped five-level change The transformation of parallel operation and newly make, it is easy to implement easy.Contrast is pressed with other various hardware, the equalizing capacitance and equal voltage inductance used Quantity it is few, therefore it also has cost low, the characteristics of small volume.
2nd, the control strategy of the switching device of equalizer circuit is simple, requires low to the software and hardware of control module；And need not The current information of main circuit or voltage-equalizing control circuit, it is only necessary to the information of voltage of DC capacitor, own suitable for any level The pressure of DC capacitor.
3rd, the circuit particularly when transmitting watt current, can realize DC capacitor under any power factor condition Voltage press and voltage stabilizing so that the PWM depth of converter is no longer limited by DC voltage stability condition, is ensured in office Active or idle transmission is realized under the conditions of meaning modulation depth.So that the PWM depth of converter is no longer steady by DC voltage The limitation of fixed condition, ensure to realize active or idle transmission under the conditions of any modulation depth.And its is simple in construction, cost Low, reliability is high.
Brief description of the drawings
Fig. 1 is the circuit theory diagrams that the present invention is used for diode clamp bit-type five-level converter；
Fig. 2 is bridge arm electric capacity CA on five level1Voltage high capacitance CA2Electric capacity CA when low1Discharge loop (1)；
Fig. 3 is bridge arm electric capacity CA on five level1Voltage high capacitance CA2Electric capacity CA when low2Charge circuit (2)；
Fig. 4 is bridge arm electric capacity CA under five level3Voltage high capacitance CA4Electric capacity CA when low3Discharge loop (3)；
Fig. 5 is bridge arm electric capacity CA under five level3Voltage high capacitance CA4Electric capacity CA when low4Charge circuit (4)；
Fig. 6 is bridge arm electric capacity CA on five level1The low electric capacity CA of voltage2Electric capacity CA when high1Charge circuit (5)；
Fig. 7 is bridge arm electric capacity CA on five level1The low electric capacity CA of voltage2Electric capacity CA when high2Discharge loop (6)；
Fig. 8 is bridge arm electric capacity CA under five level3The low electric capacity CA of voltage4Electric capacity CA when high3Charge circuit (7)；
Fig. 9 is bridge arm electric capacity CA under five level3The low electric capacity CA of voltage4Electric capacity CA when high4Discharge loop (8)；
Figure 10 is electric capacity CA when bridge arm voltage is high on five level1With electric capacity CA2Discharge loop (9)；
Figure 11 is electric capacity CA when bridge arm voltage is high on five level3With electric capacity CA4Charge circuit (10)；
Figure 12 is electric capacity CA when bridge arm voltage is high under five level1With electric capacity CA2Charge circuit (11)；
Figure 13 is electric capacity CA when bridge arm voltage is high under five level3With electric capacity CA4Discharge loop (12).
Embodiment
The present invention is described in further detail with reference to the accompanying drawings and detailed description.
Fig. 1 is that the present invention is used for the equal piezoelectricity that diode clamp bit-type five-level converter realizes all DC capacitor voltages Road, I is auxiliary equalizer circuit, and CAS is equalizing capacitance, LA1And LA2It is equal voltage inductance, SA1-SA6Represent controlled tr tube, DA1- DA6Represent the unique diode of circulating direction, switching tube SA1With diode DA1It is common to represent auxiliary switch device A1, switching tube SA2With diode DA2It is common to represent auxiliary switch device A2, switching tube SA3With diode DA3It is common to represent auxiliary switch device A3, switching tube SA4With diode DA4It is common to represent auxiliary switch device A4, switching tube SA5With diode DA5It is common to represent auxiliary Switching device A5, switching tube SA6With diode DA6It is common to represent auxiliary switch device A6, can be specifically IGBT, IGCT, The power electronic devices such as MOSFET；II is direct current capacitors group, electric capacity CA1, electric capacity CA2, electric capacity CA3, electric capacity CA4Connect respectively Form DC capacitor group；III is three-phase diode clamper five-level converter a frames, and b frames therein, c frames are in other two-phases Diode clamp five-level converter, it is assumed that the voltage of dc source is 4Vdc, then electric capacity CA4With respect to the electricity of DC power cathode Press as 1Vdc, electric capacity CA3Voltage with respect to DC power cathode is 2Vdc, electric capacity CA2Voltage with respect to DC power cathode is 3Vdc, electric capacity CA1Voltage with respect to DC power cathode is 4Vdc；ia、ib、icFor inversion alternating current；The on off state of table 1 represents Switching tube SA1, switching tube SA2, switching tube SA3, switching tube SA4, switching tube SA5With switching tube SA6Driving and working condition, 1 Conducting is represented, 0 represents shut-off.The circuit passes through controlling switch device A1, switching device A2, switching device A3, switching device A4、 Switching device A5With switching device A6Be switched on or off so that the equal voltage inductance LA in each pulse width modulation cycle1, equal piezoelectricity Feel LA2And equalizing capacitance CAS is according to the magnitude of voltage feelings of the electric capacity in upper and lower bridge arm between the magnitude of voltage of electric capacity or upper and lower bridge arm Condition respectively with electric capacity CA1, electric capacity CA2, electric capacity CA3With electric capacity CA4Connection, realize the pressure of each electric capacity；Electric capacity CA in i.e. upper bridge arm1 Voltage is high, and electric capacity CA2When voltage is low, pass through switching tube SA1, equal voltage inductance LA1Series connection forms electric capacity CA1Discharge loop (1) electric capacity CA, is reduced1Voltage, pass through equal voltage inductance LA1, diode DA2, diode DA3Series connection forms electric capacity CA2Charging Loop (2), increase electric capacity CA2Voltage；Instantly electric capacity CA in bridge arm3Voltage is high, and electric capacity CA4When voltage is low, pass through switching tube SA4, switching tube SA5, equal voltage inductance LA2Series connection forms electric capacity CA3Discharge loop (3), reduce electric capacity CA3Voltage, by equal Voltage inductance LA2, diode DA6Series connection forms electric capacity CA4Charge circuit (4), increase electric capacity CA4Voltage；When electric in upper bridge arm Hold CA1Voltage is low, and electric capacity CA2When voltage is high, pass through diode DA1, equal voltage inductance LA1Series connection forms electric capacity CA1Charging return Road (5), increase electric capacity CA1Voltage, pass through equal voltage inductance LA1, switching tube SA2, switching tube SA3Series connection forms electric capacity CA2Put Electrical circuit (6), reduce electric capacity CA2Voltage；Instantly electric capacity CA in bridge arm3Voltage is low, and electric capacity CA4When voltage is high, pass through two poles Pipe DA4, diode DA5, equal voltage inductance LA2Series connection forms electric capacity CA3Charge circuit (7), increase electric capacity CA3Voltage, pass through Equal voltage inductance LA2, switching tube SA6Series connection forms electric capacity CA4Discharge loop (8), reduce electric capacity CA4Voltage；When upper bridge arm electricity When pressing high, pass through switching tube SA1, switching tube SA2, equalizing capacitance CAS, diode DA4Series connection forms electric capacity CA1With electric capacity CA2's Discharge loop (9), reduce electric capacity CA1With electric capacity CA2Voltage, pass through switching tube SA3, equalizing capacitance CAS, diode DA5, two Pole pipe DA6Series connection forms electric capacity CA3With electric capacity CA4Charge circuit (10), increase electric capacity CA3With electric capacity CA4Voltage；Instantly bridge When arm voltage is high, pass through diode DA1, diode DA2, equalizing capacitance CAS, switching tube SA4Series connection forms electric capacity CA1And electric capacity CA2Charge circuit (11), increase electric capacity CA1With electric capacity CA2Voltage, pass through diode DA3, equalizing capacitance CAS, switching tube SA5, switching tube SA6Series connection forms electric capacity CA3With electric capacity CA4Discharge loop (12), reduce electric capacity CA3With electric capacity CA4Voltage.
The basic functional principle of the circuit is：Pass through equal voltage inductance LA1, equal voltage inductance LA2With equalizing capacitance CAS voltage The energy of high electric capacity is to shifting on the low electric capacity of voltage.In order to realize such scheme, 4 electric capacity in five level circuits are needed 12 charge and discharge electric pathways are provided, table 1 is the on off state table for the mixing equalizer circuit for being applicable five level：Respectively in corresponding table 1 12 kinds of PWM on off states and Fig. 2-Figure 13 12 loop explanations.
SA1 SA2 SA3 SA4 SA5 SA6
PWM1 1 0 0 0 0 0
PWM2 0 0 0 0 0 0
PWM3 0 0 0 1 1 0
PWM4 0 0 0 0 0 0
PWM5 0 0 0 0 0 0
PWM6 0 1 1 0 0 0
PWM7 0 0 0 0 0 0
PWM8 0 0 0 0 0 1
PWM9 1 1 0 0 0 0
PWM10 0 0 1 0 0 0
PWM11 0 0 0 1 0 0
PWM12 0 0 0 0 1 1
Table 1
It is explained individually below：
As electric capacity CA in upper bridge arm1Voltage specific capacitance CA2Gao Shi：
Now need electric capacity CA1To equal voltage inductance LA1Electric discharge, using the on off state shown in the PWM1 in table 1, that is, is switched Pipe SA1Conducting, other gate-controlled switch shut-offs.Now the loop of electric current is as shown in Fig. 2 i.e. electric capacity CA1Discharge current pass through switch Pipe SA1To equal voltage inductance LA1Charging, and return to electric capacity CA1Negative pole.Therefore, stage electric capacity CA1Voltage declines, equal voltage inductance LA1Electric current rises.
Due to equal voltage inductance LA1Middle electric current is not mutated, it is necessary to voltage inductance LA1To electric capacity CA2Electric discharge, using in table 1 On off state shown in PWM2, i.e., whole gate-controlled switch shut-offs.Now the path of electric current is as shown in figure 3, i.e. equal voltage inductance LA1's Discharge current is directly to electric capacity CA2Electric discharge, and pass through diode DA3, diode DA2Flow back to.
Instantly electric capacity CA in bridge arm3Voltage specific capacitance CA4Gao Shi：
Now need electric capacity CA3To equal voltage inductance LA2Electric discharge, using the on off state shown in the PWM3 in table 1, that is, is switched Pipe SA4With switching tube SA5Conducting, other gate-controlled switch shut-offs.Now the loop of electric current is as shown in figure 4, i.e. electric current passes through switching tube SA4With switching tube SA5To equal voltage inductance LA2Charging, and return to electric capacity CA3Negative pole.Therefore, stage electric capacity CA3Voltage decline, Equal voltage inductance LA2Electric current rises.
Due to equal voltage inductance LA2Middle electric current is not mutated, it is necessary to voltage inductance LA2To electric capacity CA4Electric discharge, using in table 1 On off state shown in PWM4, i.e., whole gate-controlled switch shut-offs.Now the loop of electric current is as shown in figure 5, i.e. equal voltage inductance LA2's Discharge current is directly to electric capacity CA4Electric discharge, and pass through diode DA6Flow back to.
As electric capacity CA in upper bridge arm2Voltage specific capacitance CA1Gao Shi：
Now need electric capacity CA2To equal voltage inductance LA1Electric discharge, using the on off state shown in the PWM6 in table 1, that is, is switched Pipe SA2With switching tube SA7Conducting, other gate-controlled switch shut-offs.Now the loop of electric current is as shown in fig. 7, i.e. electric capacity CA2Electric discharge Electric current is directly to equal voltage inductance LA1Charging, and pass sequentially through switching tube SA2With switching tube SA3Return to electric capacity CA2Negative pole.Cause This, stage electric capacity CA2Voltage declines, equal voltage inductance LA1Electric current rises.
Due to equal voltage inductance LA1Middle electric current is not mutated, it is necessary to voltage inductance LA1To electric capacity CA1Electric discharge, using in table 1 On off state shown in PWM5, i.e., whole gate-controlled switch shut-offs.Now the loop of electric current is as shown in fig. 6, i.e. equal voltage inductance LA2's Discharge current passes through diode DA1To electric capacity CA1Electric discharge.
Instantly electric capacity CA in bridge arm4Voltage specific capacitance CA3Gao Shi：
Now need electric capacity CA4To equal voltage inductance LA2Electric discharge, using the on off state shown in the PWM8 in table 1, that is, is switched Pipe SA6Conducting, other gate-controlled switch shut-offs.Now the loop of electric current is as shown in figure 9, i.e. electric capacity CA4Discharge current directly to equal Voltage inductance LA2Charging, and pass through switching tube SA6Return to electric capacity CA4Negative pole.Therefore, stage electric capacity CA4Voltage declines, pressed Inductance LA2Electric current rises.
Due to equal voltage inductance LA2Middle electric current is not mutated, it is necessary to voltage inductance LA2To electric capacity CA3Electric discharge, using in table 1 On off state shown in PWM7, i.e., whole gate-controlled switch shut-offs.Now the loop of electric current is as shown in figure 8, i.e. equal voltage inductance LA2's Discharge current passes through diode DA5With diode DA4To electric capacity CA3Electric discharge.
When the voltage of bridge arm under the voltage ratio of upper bridge arm is high：
Now need electric capacity CA1With electric capacity CA2Equalizing capacitance CAS is discharged, using the switch shape shown in the PWM9 in table 1 State, i.e. switching tube SA1With switching tube SA2Conducting, other gate-controlled switch shut-offs.Now the loop of electric current is as shown in Figure 10, i.e. electric current By switching tube SA1With switching tube SA2Charged to equalizing capacitance CAS, and diode is passed sequentially through from equalizing capacitance CAS negative pole DA4Return to electric capacity CA2.Therefore, stage electric capacity CA1With electric capacity CA2Voltage declines, equalizing capacitance CAS voltages rise.
The voltage of upper and lower bridge arm is pressed, now need equalizing capacitance CAS to electric capacity CA3With electric capacity CA4Electric discharge, use The on off state shown in PWM10 in table 1, i.e. switching tube SA3Conducting, other gate-controlled switch shut-offs.Now the loop of electric current is such as Shown in Figure 11, i.e., electric current passes through switching tube SA3To electric capacity CA3With electric capacity CA4Charging, and pass through diode DA6With diode DA5Return To equalizing capacitance CAS.Therefore, the decline of stage equalizing capacitance CAS voltages, electric capacity CA3With electric capacity CA4Voltage rises.
Instantly when the voltage of bridge arm is high in the voltage ratio of bridge arm：
Now need electric capacity CA3With electric capacity CA4Equalizing capacitance CAS is discharged, using the switch shape shown in the PWM12 in table 1 State, i.e. switching tube SA5With switching tube SA6Conducting, other gate-controlled switch shut-offs.Now the loop of electric current is as shown in figure 13, i.e. electric capacity CA3With electric capacity CA4Discharge current pass through diode DA3Discharged to equalizing capacitance CAS, and pass sequentially through switching tube SA5And switch Pipe SA6Return to electric capacity CA4Negative pole.Therefore, stage electric capacity CA3With electric capacity CA4Voltage declines, on equalizing capacitance CAS voltages Rise.
The voltage of upper and lower bridge arm is pressed, now need equalizing capacitance CAS to electric capacity CA1With electric capacity CA2Electric discharge, use The on off state shown in PWM11 in table 1, i.e. switching tube SA4Conducting, other gate-controlled switch shut-offs.Now the loop of electric current is such as Shown in Figure 12, i.e., electric current passes through diode DA2With diode DA1To electric capacity CA1With electric capacity CA2Charging, and pass through switching tube SA4Return To equalizing capacitance CAS.Therefore, the decline of stage equalizing capacitance CAS voltages, electric capacity CA1With electric capacity CA2Voltage rises.
Above-mentioned 12 kinds of mode of operations are electric capacity CA1, electric capacity CA2, electric capacity CA3With electric capacity CA4Provide respective charging and put Electrical circuit.Therefore, pressure can complete the pressure of a pair of electric capacity by two steps every time, generally select voltage highest and voltage is minimum A pair of electric capacity between operated.After repeatedly above-mentioned pressure step, DC bus capacitor CA1, electric capacity CA2, electric capacity CA3With Electric capacity CA4Voltage will tend to equal.

Claims (3)

1. a kind of equalizer circuit of five-level converter, including five-level converter III, direct current capacitors group II and auxiliary are pressed Circuit I is formed, and the input of five-level converter III is connected with the output of direct current capacitors group II, the electric capacity in DC capacitor group II CA1, electric capacity CA2, electric capacity CA3, electric capacity CA4One group of electric capacity pair is composed in series respectively, aids in the switching device A in equalizer circuit I2、 Switching device A3With switching device A4, switching device A5One group of switch pair is composed in series respectively；Characterized in that, aid in equal piezoelectricity Road I is by equalizing capacitance CAS, equal voltage inductance LA1, equal voltage inductance LA2With switch to forming；Equalizing capacitance CAS positive termination derailing switch Part A2, switching device A3For the switch of composition between, equalizing capacitance CAS negative terminal meets switching device A4, switching device A5Composition Switch is between；Electric capacity CA1Anode and switching device A1One end be connected, negative terminal passes through equal voltage inductance LA1With switching device A1 The other end be connected；Electric capacity CA4Negative terminal and switching device A6One end be connected, anode passes through equal voltage inductance LA2With switching device A6The other end be connected；Switching device A2With switching device A3One end of switch pair and equal voltage inductance LA1It is connected, the other end and electricity Hold CA2Negative terminal be connected；Switching device A4With switching device A5One end of switch pair and equal voltage inductance LA2It is connected, the other end and electricity Hold CA3Anode be connected；The midpoint of two switches pair picks out to be connected with equalizing capacitance CAS both ends.
A kind of 2. equalizer circuit of five-level converter according to claim 1, it is characterised in that：The equalizer circuit and five The DC side of level converter III is connected, and the size of equalizing capacitance and equal voltage inductance determines according to the capacity of DC bus capacitor.
A kind of 3. method for equalizing voltage of five-level converter, it is characterised in that：Control device passes through controlling switch device A1, derailing switch Part A2, switching device A3, switching device A4, switching device A5With switching device A6Be switched on or off so that each pulsewidth adjust Equal voltage inductance LA in cycle processed1, equal voltage inductance LA2With equalizing capacitance CAS according to the magnitude of voltage of electric capacity in upper and lower bridge arm or it is upper, Between lower bridge arm the magnitude of voltage situation of electric capacity respectively with electric capacity CA1, electric capacity CA2, electric capacity CA3With electric capacity CA4Connection, realizes each electric capacity Pressure；Electric capacity CA in i.e. upper bridge arm1Voltage is high, and electric capacity CA2When voltage is low, pass through switching tube SA1, equal voltage inductance LA1Series connection Form electric capacity CA1Discharge loop (1), reduce electric capacity CA1Voltage, pass through equal voltage inductance LA1, diode DA2, diode DA3 Series connection forms electric capacity CA2Charge circuit (2), increase electric capacity CA2Voltage；Instantly electric capacity CA in bridge arm3Voltage is high, and electric capacity CA4When voltage is low, pass through switching tube SA4, switching tube SA5, equal voltage inductance LA2Series connection forms electric capacity CA3Discharge loop (3), drop Low electric capacity CA3Voltage, pass through equal voltage inductance LA2, diode DA6Series connection forms electric capacity CA4Charge circuit (4), increase electric capacity CA4Voltage；As electric capacity CA in upper bridge arm1Voltage is low, and electric capacity CA2When voltage is high, pass through diode DA1, equal voltage inductance LA1String Connection forms electric capacity CA1Charge circuit (5), increase electric capacity CA1Voltage, pass through equal voltage inductance LA1, switching tube SA2, switching tube SA3Series connection forms electric capacity CA2Discharge loop (6), reduce electric capacity CA2Voltage；Instantly electric capacity CA in bridge arm3Voltage is low, and electric Hold CA4When voltage is high, pass through diode DA4, diode DA5, equal voltage inductance LA2Series connection forms electric capacity CA3Charge circuit (7), Increase electric capacity CA3Voltage, pass through equal voltage inductance LA2, switching tube SA6Series connection forms electric capacity CA4Discharge loop (8), reduce electricity Hold CA4Voltage；When upper bridge arm voltage is high, pass through switching tube SA1, switching tube SA2, equalizing capacitance CAS, diode DA4Series connection Form electric capacity CA1With electric capacity CA2Discharge loop (9), reduce electric capacity CA1With electric capacity CA2Voltage, pass through switching tube SA3, press Electric capacity CAS, diode DA5, diode DA6Series connection forms electric capacity CA3With electric capacity CA4Charge circuit (10), increase electric capacity CA3With Electric capacity CA4Voltage；Instantly when bridge arm voltage is high, diode DA is passed through1, diode DA2, equalizing capacitance CAS, switching tube SA4String Connection forms electric capacity CA1With electric capacity CA2Charge circuit (11), increase electric capacity CA1With electric capacity CA2Voltage, pass through diode DA3、 Equalizing capacitance CAS, switching tube SA5, switching tube SA6Series connection forms electric capacity CA3With electric capacity CA4Discharge loop (12), reduce electric capacity CA3With electric capacity CA4Voltage.
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