CN110474549A - A kind of single-phase cascaded H-bridges current transformer distributing phase-shift PWM modulator approach - Google Patents
A kind of single-phase cascaded H-bridges current transformer distributing phase-shift PWM modulator approach Download PDFInfo
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- CN110474549A CN110474549A CN201910762828.3A CN201910762828A CN110474549A CN 110474549 A CN110474549 A CN 110474549A CN 201910762828 A CN201910762828 A CN 201910762828A CN 110474549 A CN110474549 A CN 110474549A
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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
-
- 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
- H02M7/4835—Converters with outputs that each can have more than two voltages levels comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
- H02M1/007—Plural converter units in cascade
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Ac-Ac Conversion (AREA)
Abstract
The present invention discloses a kind of single-phase cascaded H-bridges current transformer distributing phase-shift PWM modulator approach.This method realizes the phase-shift PWM of single-phase cascaded H-bridges current transformer by the local controller using only each power cell.Utilize all power modules this characteristic of output electric current having the same, the fundametal compoment of output electric current is extracted by the local controller of each power cell, fundamental current zero-acrross ing moment is used as to the basic point for defining carrier wave angle and dynamic regulation is carried out to carrier phase angle, to realize each module carrier interleaving and phase-shift PWM modulation.
Description
Technical field
The present invention relates to PWM modulation fields, more particularly to a kind of single-phase cascaded H-bridges current transformer distributing phase-shift PWM tune
Method processed.
Background technique
Distributed DC power, including PV, energy-storage battery etc. are often applied to AC load power supply or high pressure in a collaborative manner
In grid-connected.In various types of power converters, cascaded H-bridges (CHB) current transformer is received more and more attention, because they
With multiple DC ports, the interconnection demand of low pressure distributed DC power Yu higher voltage level Grid can satisfy.In general,
CHB converter system needs a central controller to carry out closed-loop control and PWM drive signal generation.Wherein, phase-shift PWM is modulated
It is widely adopted to reduce influence of the switching frequency harmonic wave to converter output voltage.However, there are low spirits for centralized control framework
The problem of activity and reliability, especially for the high pressure applications for needing more batteries.
In addition, being had difficulties for some emerging application scenarios using centralized control, for example, being installed on different location
Distributed generation resource can form cascade connection type micro-capacitance sensor by Long-range links, and in this scenario, central controller sends pwm control signal
Be sent to each power cell by long signal wire, the system due to interference and noise it is extremely sensitive, be easy to happen control
Failure is accidentally protected.In order to solve this problem, system is controlled frequently with factor inverse dip to realize multiple concatenated power lists
Member shares workload demand.Although shared power is that dispersion carries out, PWM gate carrier wave is the local number by power supply unit
Word processing device independently generates.Therefore, it is necessary to bulky LC filters to filter out the excessively multipair CHB transformation of output harmonic wave component
The influence of device output voltage.
Summary of the invention
Purpose of the invention is to overcome the shortcomings in the prior art, provides a kind of single-phase cascaded H-bridges current transformer dispersion
Formula phase-shift PWM modulator approach.This method realizes single-phase Cascade H bridging by the local controller using only each power cell
Flow the phase-shift PWM of device.Using all power modules this characteristic of output electric current having the same, pass through the sheet of each power cell
Ground controller extracts the fundametal compoment of output electric current, and fundamental current zero-acrross ing moment is used as and defines the basic point of carrier wave angle and to load
Wave phase angle carries out dynamic regulation, to realize each module carrier interleaving and phase-shift PWM modulation.
The purpose of the present invention is what is be achieved through the following technical solutions:
A kind of single-phase cascaded H-bridges current transformer distributing phase-shift PWM modulator approach, comprising the following steps:
(1) measurement cascaded H-bridges export current instantaneous value Iind, while obtaining the fundamental current signal that cascaded H-bridges are carved at the same time
Phase angle thetaIL；
(2) capture gained θILThe moment corresponds to fundamental current phase angle theta before and after zero passageIL(k-1) and θIL(k), record corresponds to respectively
Carrier wave Counter Value CNT, and convert carrier wave Counter Value CNT to the carrier phase angle at moment before and after zero passageWithCalculation formula are as follows:
Wherein PRD is the count threshold of carrier wave counter direction overturning, and DIR is carrier wave counter counting direction, works as carrier wave
DIR value is 1 when counter counting forward, and DIR value is 0 when counting in reverse；
(3) with the fundamental current phase angle and carrier phase angle at moment before and after current over-zero, estimated by the method for linear interpolation
Zero crossing carrier phase angleBy zero crossing carrier phase angleIt is sent into pi controller；Linear interpolation estimation meter
Calculate formula are as follows:
For the carrier phase angle of estimation；
(4) in phase angle adjustment controller, each power cell has to be set in advance according to cascaded H-bridges phase shift modulation principle
Correspondence phase angleIt willWithMake difference and be sent into pi controller, obtains carrier frequency adjustment amountCalculation formula are as follows:
Wherein GadjIt (z) is the corresponding transmission function of pi controller adjusted for phase angle, kpIt is proportional integration control
The ratio term coefficient of device processed, kiIntegral item coefficient；Ts is the sampling time, and one power frequency period of the pi controller executes one
It is secondary, therefore Ts is the time of a power frequency period；
(5) carrier frequency adjustment amount obtained by step (4)Carrier wave meter is converted to by the corresponding relationship of frequency and period
The counting turn threshold PRD that number device should be setrefAnd update the value of carrier cycle register in DSP；Calculation formula are as follows:
Further, in step (2) (3), this characteristic of same current is flowed through using concatenated power module, is extracted in electric current
Periodical information as synchronization signal；Periodical information in the electric current includes fundamental current phase angle, harmonic current phase angle
And current zero-crossing point.
Compared with prior art, the beneficial effects brought by the technical solution of the present invention are as follows:
1. the present invention is directed to cascaded H-bridges converter, a kind of distributing phase-shift PWM method is proposed.By each power cell
Over-sampling output electric current as an intrinsic synchronization signal.Using the synchronization signal, output electric current can be accurately identified
Digital carrier phase angle when zero passage.Then, the method slowly adjusted using closed-loop digital carrier wave angle, needed for realizing in the steady state
Phase-shift PWM.This method is greatlyd improve without using any communication line and central controller without additional detection circuits
The flexibility and reliability of cascaded H-bridges current transformers.
2. this method can realize that cascaded H-bridges modularization distributing controls.It can simplify Cascade H bridge inverter installation and debugging
Journey.Central controller is no longer needed using Cascade H bridging parallel operation after this method, does not also need to lead between the local controller of each module
Believe route.Improve the application flexibility of cascaded H-bridges.
Detailed description of the invention
Fig. 1 is cascade of embodiment of the present invention H bridge current transformer control structure schematic diagram.
Fig. 2 is the capture of current phase angle zero passage and linear interpolation structure schematic diagram in the present invention.
Fig. 3 is that application carrier phase angle closed loop of the present invention adjusts control block diagram.
Fig. 4 a is Cascade H bridging parallel operation output PWM voltage, output current wave before the application present invention.
Fig. 4 b is Cascade H bridging parallel operation output PWM voltage, output current wave after the application present invention.
Fig. 5 is that application present invention front and back Cascade H bridging parallel operation exports electric current THD comparison diagram.
Specific embodiment
The present invention is described in further detail below in conjunction with the drawings and specific embodiments.It should be appreciated that described herein
Specific embodiment be only used to explain the present invention, be not intended to limit the present invention.
By taking the cascaded H-bridges current transformer of isolated operation as an example, Fig. 1 is the circuit of present invention specific embodiment under the operating condition
Figure.As shown in Figure 1, power circuit includes single-phase cascaded H-bridges converter and output filter, filter capacitor voltage VPCCBy Cascade H
Bridge current transformer control, to meet local load power demands.Local load current is ILoad, for prominent core methed of the present invention
Specific embodiment, each modular unit DC side are set with the ideal DC source of same DC voltage.It include grade in Fig. 1
Join H bridge inverse dip control structure, which is the required part of cascaded H-bridges decentralised control, but belongs to prior art, therefore this
Text repeats no more.
The present invention realizes the phase-shift PWM of CHB converter by the Partial controll to each power cell.Firstly, not
In the case where measuring output voltage, the power factor of each power cell is estimated.Then, it is controlled using power factor inverse dip real
Existing power is shared.On this basis, the local control of each power cell of the present invention extracts the fundametal component of output electric current, and
The carrier wave angle of each power cell is identified as basic point using zero-crossing timing.Then, it using the adjustment at carrier phase angle, realizes
Online PWM phase shift modulation.
Specifically, the step of present invention is for cascaded H-bridges current transformer PWM phase shifting control is as follows:
Step 1: each power module measures cascaded H-bridges output current instantaneous value I respectivelyind, while obtaining this when of cascaded H-bridges
Carve fundamental current signal phase angle thetaIL.Since each power module flows through same electric current, the local sensor measurement of each module
Gained current waveform is almost consistent.
Step 2: as shown in Figure 1, recording corresponding carrier wave Counter Value CNT, and it is translated into the zero passage front and back moment
Carrier phase angleWithCalculation formula are as follows:
Wherein PRD is the count threshold of carrier wave counter direction overturning, and DIR is carrier wave counter counting direction.Work as carrier wave
The value is 1 when counter counting forward, and the value is 0 when counting in reverse.
Step 3: as shown in Fig. 2, closing on the current phase angle θ of current first harmonics phase angle zero crossingIL(k-1) and θIL(k) it is caught
It obtains, during this period, carrier phase angle is in kth -1thAnd kthThe value in secondary sampling interval is captured, i.e.,With
Since digital carrier phase angle and output current phase angle have good linear relationship in shorter time interval, such as Fig. 2 lower half
Shown in part, the carrier wave angle of the exact time of estimation output current phase angle zero passage are as follows:
For the carrier phase angle of estimation.
Step 4: as shown in figure 3, in phase angle adjustment controller, each power cell has according to cascaded H-bridges phase shift modulation
The correspondence phase angle that principle is set in advanceIt willWithMake difference and be sent into PI controller, obtains carrier frequency
Adjustment amountCalculation formula are as follows:
Wherein GadjIt (z) is the corresponding transmission function of pi controller adjusted for phase angle, kpIt is proportional integration control
The ratio term coefficient of device processed, kiIntegral item coefficient.Ts is the sampling time, once, therefore one power frequency period of the controller executes
The value is the time of a power frequency period.；
Step 5: carrier frequency adjustment amount obtained by step 4Carrier wave is converted to by the corresponding relationship in frequency and period
The counting turn threshold PRD that counter should be setrefAnd update the Value Data in DSP register.Calculation formula are as follows:
The method proposed has carried out experiment test on small test model machine, and experiment is divided into two stages, two ranks
Section control mode is different.In the 1st stage, all power cells are all to give random reference voltage starting phase angle.In order to
Make to compare more intuitively, in the application of stage 1, the present invention is perfectly aligned by the carrier wave of each power cell；In the 2nd stage, by inverse dip
Control and phase-shift PWM controlled are applied to system simultaneously.
Fig. 4 a illustrates output voltage, PCC voltage, output electric current and the load current wave of the 1st multi-stage cascade power module
Shape, it can be seen that PCC voltage waveform high distortion, and it is irregular that it, which exports PWM voltage,.In second stage, such as Fig. 4 b institute
Show, using distributing phase shifting control algorithm of the invention, output voltage becomes seven level PWM waveforms of high uniformity.Meanwhile by
In the reduction of output voltage HF switch harmonic component, shown in PCC voltage become height sinusoidal waveform.
PCC voltage is as shown in Figure 5 in the harmonic spectrum of three phases, it can be seen that from stage 1 to the stage 2, PCC's is total
Harmonic distortion (THDs) is respectively 15.02% and 3.49%.
To sum up, the present invention is directed to CHB converter, proposes a kind of distributing phase-shift PWM method.The essence of this method be by
The output electric current of each power cell synchronizer intrinsic as one.Using the synchronizer, base stage can be accurately identified
Export digital carrier phase angle when current over-zero.Then, it using closed-loop digital carrier wave angle regulation method, realizes in the steady state
Phase-shift PWM appropriate.
The present invention is not limited to embodiments described above.Above the description of specific embodiment is intended to describe and say
Bright technical solution of the present invention, the above mentioned embodiment is only schematical, is not restrictive.This is not being departed from
In the case of invention objective and scope of the claimed protection, those skilled in the art may be used also under the inspiration of the present invention
The specific transformation of many forms is made, within these are all belonged to the scope of protection of the present invention.
Claims (2)
1. a kind of single-phase cascaded H-bridges current transformer distributing phase-shift PWM modulator approach, which comprises the following steps:
(1) measurement cascaded H-bridges export current instantaneous value Iind, while obtaining the fundamental current signal phase angle that cascaded H-bridges are carved at the same time
θIL；
(2) capture gained θILThe moment corresponds to fundamental current phase angle theta before and after zero passageIL(k-1) and θIL(k), corresponding load is recorded respectively
Wave Counter Value CNT, and convert carrier wave Counter Value CNT to the carrier phase angle at moment before and after zero passageWithCalculation formula are as follows:
Wherein PRD is the count threshold of carrier wave counter direction overturning, and DIR is carrier wave counter counting direction, when carrier wave counts
DIR value is 1 when device counting forward, and DIR value is 0 when counting in reverse；
(3) with the fundamental current phase angle and carrier phase angle at moment before and after current over-zero, zero passage is estimated by the method for linear interpolation
Point carrier phase angleBy zero crossing carrier phase angleIt is sent into pi controller；Linear interpolation estimates calculation formula
Are as follows:
For the carrier phase angle of estimation；
(4) in phase angle adjustment controller, each power cell has pair being set in advance according to cascaded H-bridges phase shift modulation principle
Answer phase angleIt willWithMake difference and be sent into pi controller, obtains carrier frequency adjustment amountMeter
Calculate formula are as follows:
Wherein GadjIt (z) is the corresponding transmission function of pi controller adjusted for phase angle, kpIt is pi controller
Ratio term coefficient, kiIntegral item coefficient；Ts is the sampling time, and one power frequency period of the pi controller executes once,
Therefore Ts is the time of a power frequency period；
(5) carrier frequency adjustment amount obtained by step (4)Carrier wave counter institute is converted to by the corresponding relationship of frequency and period
The counting turn threshold PRD that should be setrefAnd update the value of carrier cycle register in DSP；Calculation formula are as follows:
。
2. single-phase cascaded H-bridges current transformer distributing phase-shift PWM modulator approach according to claim 1, which is characterized in that step
Suddenly in (2) (3), this characteristic of same current is flowed through using concatenated power module, extracts the periodical information in electric current as same
Walk signal；Periodical information in the electric current includes fundamental current phase angle, harmonic current phase angle and current zero-crossing point.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112311005A (en) * | 2020-09-29 | 2021-02-02 | 广西大学 | Device and control method of single-phase multi-level cascade H-bridge converter |
| CN112311004A (en) * | 2020-09-29 | 2021-02-02 | 广西大学 | Control method of cascaded H-bridge converter under harmonic background of power grid |
| US11799393B2 (en) | 2021-08-26 | 2023-10-24 | Delta Electronics (Shanghai) Co., Ltd. | Dispersed carrier phase-shifting method and system |
-
2019
- 2019-08-19 CN CN201910762828.3A patent/CN110474549A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112311005A (en) * | 2020-09-29 | 2021-02-02 | 广西大学 | Device and control method of single-phase multi-level cascade H-bridge converter |
| CN112311004A (en) * | 2020-09-29 | 2021-02-02 | 广西大学 | Control method of cascaded H-bridge converter under harmonic background of power grid |
| US11799393B2 (en) | 2021-08-26 | 2023-10-24 | Delta Electronics (Shanghai) Co., Ltd. | Dispersed carrier phase-shifting method and system |
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Application publication date: 20191119 |