CN109742961A - A kind of heat balance control method of modularization multi-level converter - Google Patents
A kind of heat balance control method of modularization multi-level converter Download PDFInfo
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Abstract
A kind of heat balance control method of modularization multi-level converter, the proposition of this method novelty: modular multilevel balances the thermal unbalance problem between submodule using active thermal balance control there are thermal unbalance phenomenon between submodule；(1) active thermal balance proposed using this method is controlled to balance the junction temperature between submodule, and the unbalanced phenomenon of temperature can be improved between submodule；(2) disequilibrium of the Temperature Distribution and junction temperature of corresponding power semiconductor can reduce between submodule, and temperature change number and the number to reach a high temperature can also have opposite improvement.(3) and the junction temperature that can reduce between submodule on the basis of capacitor voltage balance of thermal balance algorithm is poor, the performance without reducing system.(4) this balance method also can reduce the maximum temperature of power semiconductor, so that the service life of power semiconductor be made to increase.
Description
Technical field
The content of present invention is related to a kind of heat balance control method of modularization multi-level converter, solves Electrical transformation
The thermal unbalance problem of multilevel converter in device is a kind of heat balance method being embedded in capacitor voltage balance algorithm.
Background technique
Modularization multi-level converter is as a kind of novel multi-level voltage source current converter (voltage-sourced
Converter, VSC), since it is highly suitable for direct current transportation occasion, obtain the height of international academic community and industry
Concern.Modularization multi-level converter (MMC), by its own, loss is low, harmonic distortion is small, scalability is high, is easy to construct
The significant advantages such as multiterminal element network have gradually replaced two level/three-level converter in high-voltage large-capacity flexible direct current field
In application.MMC will be balanced the capacitance voltage submodule on bridge arm for stable operation, and not consider in submodule
Balance between the loss and junction temperature of power device.In practical applications, in submodule capacitor of different sizes, and capacitance voltage
Balanced action in the submodule of low capacitance on-state loss and switching loss it is higher, lead to the semiconductor devices in submodule
Temperature also increase, cause the imbalance of temperature between different submodules.The submodule for bearing more to be lost can generate more
Temperature, the reduction of the excessively high damage and service life that will cause device of temperature.And temperature repeatedly changes can generate thermal and mechanical stress, meeting
Lead to the damage of power device connecting material in submodule, may result in component failure after long-term temperature variation.Both at home and abroad
Scholar has been devoted in the heat balance control method research of modular multilevel.
Summary of the invention
Goal of the invention:
The present invention provides a kind of heat balance control method based on modularization multi-level converter, and the purpose is to solve height
Peak load operation and the influence in service life of the intermodule temperature imbalance to inverter.What it can be controlled in capacitor voltage balance
On the basis of thermal balance between control submodule (Sub-module, SM)；Temperature change variation between each submodule is introduced, is protected
The temperature difference on the basis of not changing submodule output voltage waveforms and waveform quality between balanced each submodule is demonstrate,proved, submodule is prevented
Semiconductor devices in block causes aging or damage due to high temperature or frequent temperature change.It can be achieved between different submodules
Thermal stress distribution extends the service life of each submodule.
Technical solution:
A kind of heat balance control method of modularization multi-level converter, it is characterised in that: the proposition of this method novelty:
For modular multilevel there are thermal unbalance phenomenon between submodule, the heat balanced between submodule using active thermal balance control is uneven
Weighing apparatus problem；The maximum temperature difference allowed between each submodule is being set in heat balance control method, in each group submodule
The m of blockiChoose maximum and minimum value m in valuemax、mmin, difference between the two is exactly maximum difference Δ m between group, sets one
Maximum difference permissible value mrefTo maintain to balance the equalized temperature between each submodule；This method design submodule allocation flow is worked as
mrefWhen less than Δ m, submodule is ranked up according to arm current direction, arm electric current is timing, and submodule is pressed to the size of m value
Ascending order arrangement.Work as mrefWhen greater than Δ m, submodule is arranged by the size descending of m value.The allocation flow will be between submodule
Temperature in embedded capacitor balance of voltage method by being balanced.Condenser voltage Vcu and device junction temperature T may be implementedj
Balance；According to the operation data of modularization multi-level converter in this method, the number for the submodule that need to be connected is calculated, then
Determine that the submodule for needing to put into or cut off, the submodule even put into are according to the charge status for having put into submodule
Charged state, and when need to put into submodule, then it is the smallest that capacitance voltage, submodule deblocking temperature are chosen in the submodule having not been put to
Submodule investment；If the submodule put into is in charged state, and when need to cut out submodule, then in the submodule put into
Choose capacitance voltage maximum, the biggish submodule of submodule deblocking temperature is cut out；If the submodule put into is in discharge condition, and needs
When putting into submodule, then capacitance voltage maximum is chosen in the submodule having not been put to, the biggish submodule of submodule deblocking temperature is thrown
Enter；If the submodule put into is in discharge condition, and when need to cut out submodule, then chooses capacitor in the submodule put into
The smallest submodule of voltage is cut out.
Specifically: the power loss equivalence of IGBT and diode is respectively that two current sources export outward by this method
Power, and the heat transfer process between PN junction and device outer case then uses thermal resistance Rthc-sTAnd Rthc-sDIt indicates, wherein subscript T is indicated
The thermal resistance of IGBT, subscript D indicate the thermal resistance of anti-paralleled diode；Equally, the heat transmitting between device outer case and radiator
Process can use thermal resistance Rthc-sTAnd Rthc-sDIt indicating, specific thermal resistance parameter is found from the tables of data that manufacturer provides, it
After obtain:
Tj_T=PT(Rthc-sT+RthCH-T)+θ (6)
Tj_D=PD(Rthc-sD+RthCH-D)+θ (7)
Wherein Tj_TIt is expressed as the junction temperature of the part IGBT, Tj_DIndicate the junction temperature of diode section；PTFor the total losses of IGBT,
PDFor the total losses of anti-paralleled diode, θ indicates radiator temperature.Specifically, it is assumed that each bridge arm has n submodule, and n is logical
Often it is even number, then submodule is divided into n/2 group, every group includes 2 submodules；Meanwhile the number of each group also it is thus determined that
Get off, i.e., 1 arrives n/2 group；Submodule capacitor voltage, the temperature of IGBT temperature and anti-paralleled diode are first measured, temperature is by hot-die
Type estimation.Then the voltage of two submodules in grouping and temperature are subjected to normalizing calculating.
ai=Vc,i=∑ Vc/ 2 (i=1,2) (8)
mi=ai+bi+ci (11)
Wherein unrestricted choice of the i between submodule；aiFor the average voltage of every group of submodule；biFor the loss of IGBT
Heat production temperature superimposition value；ciFor the loss heat production superposition value of anti-paralleled diode；In the m of each group submoduleiChoose in value it is maximum and
Minimum value mmax、mmin, difference between the two is exactly maximum difference Δ m between group, need to set a maximum difference permissible value mrefTo tie up
Maintain an equal level weighing apparatus, and the submodule number that need to be connected is divided by the radix that the quotient that group number obtains is that each group need to be opened, when being allocated to remainder,
It need to be according to Δ m and mrefIt distributes, works as mrefIt does not need to be adjusted the ranking results of submodule when greater than Δ m, it can make
It is sequentially allocated with the ranking results of most initial to 1 to n/2 group.Work as mrefWhen less than Δ m, need according to arm current direction to submodule
Block is ranked up, and arm electric current is timing, submodule is arranged by the size ascending order of m value, on the contrary then descending arranges.By using institute
The solution of proposition, the temperature between submodule in embedded capacitor balance of voltage method by being balanced.Thermal balance
Control principle drawing is as shown in Figure 4.It is thereby achieved that condenser voltage VcuWith device junction temperature TjBalance.
Advantageous effect:
The present invention provides a kind of heat balance control method based on modularization multi-level converter, and MMC is due to having output
The advantages that level number is high, switching frequency is low, waveform quality is good, therefore have good future in engineering applications and current voltage source
The hot spot of type inverter research.This method is between proposing thermal equilibrium control strategy the problem of thermal unbalance MMC submodule, (1)
The active thermal balance proposed using this method is controlled to balance the junction temperature between submodule, and temperature is unbalanced between submodule
Phenomenon can be improved；(2) disequilibrium of the Temperature Distribution and junction temperature of corresponding power semiconductor can be between submodule
It reduces, temperature change number and the number to reach a high temperature can also have opposite improvement.(3) and thermal balance algorithm can be in capacitor
The junction temperature reduced between submodule on the basis of the balance of voltage is poor, the performance without reducing system.(4) this balance method also can
The maximum temperature for enough reducing power semiconductor, so that the service life of power semiconductor be made to increase.
Detailed description of the invention
Fig. 1: MMC Basic Topological
Fig. 2: the thermal model of power device in half-bridge Neutron module
Fig. 3: thermal equilibrium control flow chart
Fig. 4: the schematic diagram of thermal equilibrium control
Specific embodiment:
1) model analysis of MMC
Three-phase MMC system is made of three phase bridge arms, and each phase bridge arm is made of upper half bridge arm and lower half bridge arm two parts,
Each half bridge arm is respectively by N number of submodule and bridge arm inductance LaIt is sequentially connected in series, the output end of each phase bridge arm is from two bridge arms
The tie point of inductance is drawn.The concatenated number of its submodule is by the logical of the rated power of converter, voltage class and switching device
Stream ability and compressive resistance determine.The three-phase topological structure of typical N+1 level is as shown in Figure 1.Inverter is by 3 phase element groups
At every mutually upper and lower bridge arm has N number of submodule cooperation switching, and any time keeps while the submodule sum of investment is N, can
Maintain DC voltage UdcIt is constant.
2) loss assessment
The power loss of IGBT is mainly damaged by on-state loss, cut-off loss, switching loss and driving in the calculating of loss
Four parts composition is consumed, because the ratio that cut-off loss and drive loss account for total losses is minimum, the temperature of generation influences to ignore.Institute
Only to calculate the on-state loss and switching loss of IGBT.In the loss calculation of anti-paralleled diode, only to on-state loss and instead
Calculating is overlapped to loss is restored.
In order to estimate device junction temperature used in thermal equilibrium control strategy, need to calculate power loss.For half-bridge SM, function
Rate loss can be simply divided into two parts: on-state loss and switching loss (or reverse recovery loss of diode).IGBT and
The forward conduction voltage of diode is mainly related with conducting electric current and junction temperature, calculates the on-state loss in a complete power frequency period
It needs to integrate its voltage and current product.The on-state loss of IGBT and diode are as follows:
Wherein, Pcon,VTAnd Pcon,VDFor the on-state loss of IGBT and diode, t is time, θjJunction temperature is represented, unit is
℃；TcFor a complete power frequency period, UVTCollection penetrates the voltage between grade, i when being connected for IGBTVTFor IGBT collector current；UVD
For diode forward pressure drop, iVDFor diode forward average current.
The switching loss of IGBT and the reverse recovery loss of diode are calculated, it is available according to adding up for on-off times
The corresponding switching loss of IGBT asks its mean value to can be obtained the average switch loss power of each submodule the time, similarly
Diode reverse recovery losses can be obtained, calculating process is as follows:
Wherein, Pon,T、Poff,TAnd Prec,DRespectively represent the turn-on consumption and turn-off power loss and anti-paralleled diode of IGBT
Reverse recovery loss, unit W；t0For the initial time of computed losses；tα、tβ、tγRespectively indicate opening, turning off for IGBT
Moment and the Reverse recovery moment of diode；UCE,onIndicate the blocking voltage before IGBT is opened；UCE,offAfter indicating IGBT shutdown
Blocking voltage, unit V；UF,refBlocking voltage after indicating diode reverse recovery, unit V；UCE,refFor manufacturer institute
The reference voltage base value calculated in switching loss between collector and emitter, unit V are provided.
3) junction temperature is fed back
In order to observe the Temperature Distribution and hot property of power device in submodule, need to survey the temperature of IGBT device
Amount, and the junction temperature inside power device can not directly measure to obtain, it is therefore desirable to it is utilized by establishing thermal model to power device
Spreader surface temperature estimates its junction temperature.Therefore equivalent heater circuit model as shown in Figure 2 is established.Respectively by IGBT and two poles
The power loss equivalence of pipe is that two current sources carry out outside output power, and the heat transfer process between PN junction and device outer case is then
With thermal resistance Rthc-sTAnd Rthc-sDIt indicates, wherein subscript T indicates that the thermal resistance of IGBT, subscript D indicate the heat of anti-paralleled diode
Resistance.Equally, the heat transfer process between device outer case and radiator can use thermal resistance Rthc-sTAnd Rthc-sDIt indicates, specifically
Thermal resistance parameter can be found from the tables of data that manufacturer provides.By Fig. 2 it follows that
Tj_T=PT(Rthc-sT+RthCH-T)+θ (6)
Tj_D=PD(Rthc-sD+RthCH-D)+θ (7)
Wherein Tj_TIt is expressed as the junction temperature of the part IGBT, Tj_DIndicate the junction temperature of diode section；PTFor the total losses of IGBT,
PDFor the total losses of anti-paralleled diode, θ indicates radiator temperature.
Specifically, it is assumed that each bridge arm has n submodule (n is usually even number), then submodule is divided into n/2
Group, every group includes 2 submodules.Meanwhile the number of each group also it is thus determined that getting off, i.e., 1 arrives n/2 group.First measurement submodule electricity
Hold the temperature of voltage, IGBT temperature and anti-paralleled diode, temperature is estimated by thermal model.Then by two submodules in grouping
Voltage and temperature carry out normalizing calculating.
ai=Vc,i=∑ Vc/ 2 (i=1,2) (8)
mi=ai+bi+ci (11)
Wherein unrestricted choice of the i between submodule；aiFor the average voltage of every group of submodule；biFor the loss of IGBT
Heat production temperature superimposition value；ciFor the loss heat production superposition value of anti-paralleled diode；As described in the flow chart of figure 3, in each group submodule
MiChoose maximum and minimum value m in valuemax、mmin, difference between the two is exactly maximum difference Δ m between group, need to set one most
Big difference permissible value mrefIt maintains to balance, the submodule number that need to be connected is divided by the base that the quotient that group number obtains is that each group need to be opened
Number, need to be according to Δ m and m when being allocated to remainderrefIt distributes, works as mrefThe sequence knot to submodule is not needed when greater than Δ m
Fruit is adjusted, it can is sequentially allocated using the ranking results of most initial to 1 to n/2 group.Work as mrefWhen less than Δ m, root is needed
Submodule is ranked up according to arm current direction, arm electric current be timing, by submodule by m value size ascending order arrange, it is on the contrary then
Descending arrangement.By using the solution proposed, the temperature between submodule passes through in embedded capacitor balance of voltage method
To be balanced.Thermal equilibrium control schematic diagram is as shown in Figure 4.It is thereby achieved that condenser voltage VcuWith device junction temperature Tj
Balance.
In summary:
The inverter voltage and current value that the present invention is provided by supplier, obtains semiconductor devices under real work junction temperature
Loss, calculating analysis is carried out to the loss of submodule each in modularization multi-level converter；Pass through half-bridge Neutron module heat
Model improves existing heat balance control method；It is proposed that thermal equilibrium control is calculated on the basis of capacitor voltage balance algorithm
Method introduces weight factor, by a certain number of submodules in the temperature for considering capacitance voltage, IGBT temperature and anti-paralleled diode
Influence factor under carry out ordered arrangement.The running temperature that each submodule can be effectively reduced increases the maximum operation of MMC
Power.
Claims (2)
1. a kind of heat balance control method of modularization multi-level converter, it is characterised in that: this method utilizes active thermal balance
Control is to balance the thermal unbalance problem between submodule；Allow between each submodule being set in heat balance control method
Maximum temperature difference, in the m of each group submoduleiChoose maximum and minimum value m in valuemax、mmin, difference between the two is exactly group
Between maximum difference Δ m, set a maximum difference permissible value mrefTo maintain to balance the equalized temperature between each submodule；It should
Method design submodule allocation flow works as mrefWhen less than Δ m, submodule is ranked up according to arm current direction, arm electric current is
Timing is arranged submodule by the size ascending order of m value；Work as mrefWhen greater than Δ m, submodule is arranged by the size descending of m value；
The allocation flow is by the temperature between submodule by being balanced in embedded capacitor balance of voltage method；Realize capacitor
Voltage VcuWith device junction temperature TjBalance；According to the operation data of modular multilevel in this method, the submodule that need to be connected is calculated
Then the number of block determines the submodule for needing to put into or cut off according to the charge status for having put into submodule, has even thrown
The submodule entered is in charged state, and when need to put into submodule, then capacitance voltage, son are chosen in the submodule having not been put to
The smallest submodule investment of module temperature；If the submodule put into is in charged state, and when need to cut out submodule, then
Capacitance voltage maximum is chosen in the submodule of investment, the biggish submodule of submodule deblocking temperature is cut out；If at the submodule put into
In discharge condition, and when need to put into submodule, then choose that capacitance voltage is maximum, submodule deblocking temperature in the submodule having not been put to
Biggish submodule investment；If the submodule put into is in discharge condition, and when need to cut out submodule, then in the son put into
The smallest submodule of capacitance voltage is chosen in module to cut out.
2. a kind of heat balance control method of modularization multi-level converter according to claim 1, it is characterised in that: should
The power loss equivalence of IGBT and diode is respectively the next outside output power of two current sources by method, and outside PN junction and device
Heat transfer process between shell then uses thermal resistance Rthc-sTAnd Rthc-sDIt indicates, wherein subscript T indicates the thermal resistance of IGBT, subscript D
Indicate the thermal resistance of anti-paralleled diode；Equally, the thermal resistance R of the heat transfer process between device outer case and radiatorthc-sTWith
Rthc-sDIt indicates, specific thermal resistance parameter is found from the tables of data that manufacturer provides, obtained later:
Tj_T=PT(Rthc-sT+RthCH-T)+θ (1)
Tj_D=PD(Rthc-sD+RthCH-D)+θ (2)
Wherein Tj_TIt is expressed as the junction temperature of the part IGBT, Tj_DIndicate the junction temperature of diode section；PTFor the total losses of IGBT, PDFor
The total losses of anti-paralleled diode, θ indicate radiator temperature.Specifically, it is assumed that each bridge arm has n submodule, and n is usually
Submodule is then divided into n/2 group by even number, and every group includes 2 submodules；Meanwhile the number of each group is also it is thus determined that get off,
I.e. 1 arrives n/2 group；Submodule capacitor voltage, the temperature of IGBT temperature and anti-paralleled diode are first measured, temperature is estimated by thermal model
Meter；Then the voltage of two submodules in grouping and temperature are subjected to normalizing calculating；
mi=ai+bi+ci (6)
Wherein unrestricted choice of the i between submodule；aiFor the average voltage of every group of submodule；biFor the loss heat production of IGBT
Temperature superimposition value；ciFor the loss heat production superposition value of anti-paralleled diode；In the m of each group submoduleiChoose in value minimum and maximum
Value mmax、mmin, difference between the two is exactly maximum difference Δ m between group, need to set a maximum difference permissible value mrefTo remain flat
Weighing apparatus, the submodule number that need to be connected when being allocated to remainder, need root divided by the radix that the quotient that group number obtains is that each group need to be opened
According to Δ m and mrefIt distributes, works as mrefIt does not need to be adjusted the ranking results of submodule when greater than Δ m, that is, uses most initial
Ranking results be sequentially allocated to 1 to n/2 group；Work as mrefWhen less than Δ m, need to arrange submodule according to arm current direction
Sequence, arm electric current are timing, submodule are arranged by the size ascending order of m value, on the contrary then descending arranges.
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| CN110635683A (en) * | 2019-09-06 | 2019-12-31 | 上海交通大学 | Two-port sub-module, self-coupling type direct current transformer and modulation method thereof |
| CN111917316A (en) * | 2020-06-04 | 2020-11-10 | 东南大学 | Submodule temperature adjusting and balancing method based on centralized control of modular multilevel converter |
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| CN112803792A (en) * | 2021-02-01 | 2021-05-14 | 中南大学 | Traction converter thermal field control method and system |
| CN114492039A (en) * | 2022-01-27 | 2022-05-13 | 天津电气科学研究院有限公司 | IGBT junction temperature estimation method based on thermal impedance model |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112152495A (en) * | 2019-06-28 | 2020-12-29 | 新疆金风科技股份有限公司 | Control method and controller of modular multilevel converter |
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| CN111917316A (en) * | 2020-06-04 | 2020-11-10 | 东南大学 | Submodule temperature adjusting and balancing method based on centralized control of modular multilevel converter |
| CN112803792A (en) * | 2021-02-01 | 2021-05-14 | 中南大学 | Traction converter thermal field control method and system |
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| CN114492039A (en) * | 2022-01-27 | 2022-05-13 | 天津电气科学研究院有限公司 | IGBT junction temperature estimation method based on thermal impedance model |
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Application publication date: 20190510 |