CN105186883A - Control method of input-series output-parallel (ISOP) converter system - Google Patents

Abstract

The invention discloses a control method of an input-series output-parallel (ISOP) converter system. A three-loop control strategy is adopted; three loops comprise an output voltage loop, an input current loop and an IVS loop; and the three-loop control strategy is output voltage loop control, input current loop control and IVS loop control. The effects of a communication system on the three-loop control strategy are fully considered; a compensation link design is added; the synchronous property of each module can be ensured; good voltage and current characteristics can be obtained; and the stability and the reliability of the quality of electric energy transmitted in a repairing process by using the three-loop control strategy.

Description

A kind of control method of ISOP changer system

Technical field

The present invention relates to ISOP changer system, be specifically related to a kind of control method of ISOP changer system.

Background technology

Now, power module technology progressively becomes the trend of Development of Power Electronic Technology.For different demand, adopt modular solution, the construction cycle of power-supply system can be shortened, reduce development cost, realize high efficiency, high power density, high reliability.Therefore, in order to meet insulation request, ISOP (Input-SeriesOutput-Parallel can be adopted as required at DC-AC-DC isolation link, input side series connection, outlet side parallel connection) and IPOS (Input-ParallelOutput-Series, input side is in parallel, outlet side is connected) two kinds of compound modes.Wherein ISOP mode is applicable to the occasion of high input voltage, High-current output; IPOS mode is suitable for the occasion of low pressure input, High voltage output.As long as realize all pressing at series side in running, realize current-sharing in side in parallel, each module just can be made to bear identical power output, can ensure that system is run stably in a long term.The isolation mode mode of this multimode, can reduce the current stress of switching device and the voltage stress of rectifier diode effectively, and in high voltage, powerful application scenario, comparatively conventional single-mode block operational mode has obvious advantage.

ISOP changer system is connected at input side by multiple module, outlet side parallel combination forms, the structure of ISOP changer system refers to Fig. 1, multiple module M#1 ~ M#n, at the ISOP changer system of input side (Vin side) series connection, outlet side (Vout side) parallel combination, because input voltage all presses (IVS) and output current current-sharing (OCS) automatically to be realized by connected mode, so only need control inputs electric current current-sharing (ICS) and output voltage all to press (OVS).In fact, when ignoring circuit loss, input power is identical with power output, so ICS and OVS necessary and sufficient condition each other, when ICS realizes, OVS also can realize, and conversely when OVS realizes, ICS also can realize.

Summary of the invention

The object of the present invention is to provide a kind of control method of ISOP changer system, the net synchronization capability of each module can be ensured, extraordinary voltage and current characteristic can be obtained, use three close-loop control strategy, can guarantee to rush to repair the reliable and stable of the transmission of electricity quality of power supply.

The technical scheme realizing above-mentioned purpose is:

A control method for ISOP changer system, described ISOP changer system is connected at input side by multiple module, outlet side parallel combination forms, and it is characterized in that, described control method comprises the following steps:

Step S1, determine control strategy: adopt three close-loop control strategy, three rings comprise output-voltage loop, input current ring and IVS ring (input voltage grading ring), the control of output-voltage loop and the control composition double-loop control of input current ring, i.e. outer voltage and average current inner loop Double-loop Control Strategy, the control of outer voltage exports the reference input as current inner loop, is DC/DC conversion, input voltage fluctuation is very little, and transformer primary electric current equals module input current; The control of IVS ring is completely distributed, except the first module, other each modules are the input voltage that reference value regulates oneself according to the mean value of input voltage, and the first module itself does not have IVS control ring, the IVS ring of other all modules directly controls to be added rear negate by it, joins in the Duty ratio control of oneself, does like this and just make the total contribution of whole IVS ring to system output duty cycle be 0, thus the control of output voltage can not be affected, make IVS ring and double-loop control decoupling zero;

Step S2, determine the impact of communication system on control strategy: in ISOP changer system, the reference voltage of other modules is sended over by the first module, in this process, there is communication delay, the delay of disparate modules is different, for the impact of double-loop control by communication delay, get the delay that this delay is N module, namely

$T_d=\frac{N-1}{N}{T}_C$ (formula 1);

In formula 1: T ^dfor communication delay, T _cfor the sampling period, the delay of N module is maximum delay situation, all reaches stable in maximum delay situation, and the situation being so less than this delay is also all stable;

Cumulative each exports from the control of module input grading ring, and as primary module input Pressure and Control amount after negate, primary module itself does not have IVS control ring;

IVS ring in other modules except the first module does not affect by communication delay, be all local measurement, local control, but there is no IVS ring due to primary module, it the control of other module I VS rings is exported cumulative negate, so the IVS of primary module controls the impact by communication delay;

Step S3, design compensation link, comprises the following steps:

S31, the first compensation of design current inner ring, the loop gain Γ of current inner loop _currentfor:

${\mathrm{\Γ}}_{current}=K_{CC}\·G_i\·G_{id}\·LPF\·\frac{1}{F_m}\·\exp (-\frac{s}{2f_{sp}})$ (formula 2);

In formula 2: K _cCfor current measurement conversion coefficient; G _ifor current loop control compensates transfer function; G _idfor transformer primary electric current is to the transfer function of duty ratio, LPF is average current low pass filter; F _mfor PWM carrier amplitude; f _spfor current sample frequency;

Then by whole current inner loop, when integrally, its closed loop transfer function, G is calculated:

$G=\frac{G_i}{F_m(1+{\mathrm{\Γ}}_{current})}$ (formula 3);

By MATLAB, draw the Bode diagram of electric current loop before compensation and after compensating, after compensating, the increase of low frequency range obviously increases;

S32, finally obtains the loop gain Γ of whole outer voltage _voltage:

${\mathrm{\Γ}}_{voltage}=K_{VC}\·G_V\·G\·G_{vd}\exp (-\frac{s}{2f_r}-T_{d}s)$ (formula 4);

In formula 4, K _vCfor voltage measurement conversion coefficient; G _vfor Voltage loop control and compensation transfer function; G _vdfor output voltage is to the transfer function of duty ratio; T _dfor communication delay, f _rit is maximum equivalent sample frequency; G is the closed loop transfer function, of whole current inner loop;

In outer voltage, communication delay T _dbe dominating delay, refer step S2, rounds a circular communication maximum delay, namely

$T_d=\frac{N-1}{N}{T}_C=\frac{N-1}{{\mathrm{Nv}}_c}$ (formula 5);

In formula 5, v _cfor communication speed;

S33, for the IVS ring of primary module, its loop gain Γ _iVSfor:

${\mathrm{\Γ}}_{IVS}=K_{vc}\exp \left(\frac{-s}{2f_{sp}}\right)G_{vcd}\exp (-T_{C}s)\frac{1}{F_m}A\left(s\right)$ (formula 6);

In formula 6, K _vCfor voltage measurement conversion coefficient, F _mfor PWM carrier amplitude; G _vcdfor IVS ring compensation tache; f _spfor current sample frequency, T _cfor the sampling period, the IVS ring low-frequency gain after compensation significantly improves.

The invention has the beneficial effects as follows: the present invention adopts three close-loop control strategy, three rings comprise output-voltage loop, input current ring and IVS ring, three close-loop control strategy is that output-voltage loop and input current ring double-loop control and IVS ring control, take into full account the impact of communication system on three close-loop control strategy, and add compensation tache design, the net synchronization capability of each module can be ensured, extraordinary voltage and current characteristic can be obtained, use three close-loop control strategy, can guarantee to rush to repair the reliable and stable of the transmission of electricity quality of power supply.

Accompanying drawing explanation

Fig. 1 is the structure chart of ISOP changer system;

Fig. 2 is the flow chart of the control method of ISOP changer system of the present invention;

Fig. 3 is the schematic diagram of Double-loop Control Strategy,

Fig. 4 is ISOP changer system IVS ring schematic diagram;

Fig. 5 is the specific implementation figure of ISOP three close-loop control system under ring communication construction;

Fig. 6 is the effect diagram that communication delay controls primary module IVS;

Fig. 7 is that equivalent primary module IVS controls schematic diagram;

Fig. 8 is electric current loop Bode diagram before and after compensating;

Fig. 9 is ISOP converter voltage ring communication speed-bandwidth relationship figure;

Figure 10 is Voltage loop Bode diagram before and after compensating;

Figure 11 is ISOP converter IVS ring communication speed-bandwidth relationship figure;

Figure 12 is ISOP converter IVS ring Bode diagram before and after compensating.

Embodiment

Below in conjunction with accompanying drawing, the invention will be further described.

Refer to Fig. 1, ISOP changer system, by multiple module M#1 ~ M#n, forms at input side (Vin side) series connection, outlet side (Vout side) parallel combination.

Selected by ISOP changer system is control IVS, namely inputs Pressure and Control.Reason is that the voltage measuring input side is more easy relative to measurement outlet side electric current, and owing to being input series connection, therefore the accessory power supply of each module is not altogether, therefore measures input voltage and there is not isolating problem, very convenient.ISOP convertor controls strategy designed by this project is that three close-loop control strategy is respectively output-voltage loop, input current ring, and IVS ring.

Refer to Fig. 2, the control method of ISOP changer system of the present invention, comprises the following steps:

Step S1, determine control strategy: adopt three close-loop control strategy, three rings comprise output-voltage loop, input current ring and IVS ring (input voltage grading ring), the control of output-voltage loop and the control composition double-loop control of input current ring, i.e. outer voltage and average current inner loop Double-loop Control Strategy, the control of outer voltage exports the reference input as current inner loop, is DC/DC conversion, input voltage fluctuation is very little, and transformer primary electric current equals module input current; Refer to Fig. 3, the schematic diagram of Double-loop Control Strategy, in Fig. 3, K _vCwith K _cCbe respectively voltage and current and measure conversion coefficient, G _vand G _ibe respectively Voltage loop and current loop control compensation transfer function, LPT is average current low pass filter, F _mfor PWM carrier amplitude, G _vdand G _idbe respectively output voltage and transformer primary electric current to the transfer function of duty ratio, T _dfor communication delay, f _rmaximum equivalent sample frequency, f _spfor current sample frequency.For convenience of analyzing, sampling element being all considered as pure delay link here, getting sampling period half average delay time.

The control of IVS ring is completely distributed, except the first module M#1, other each modules are the input voltage that reference value regulates oneself according to the mean value of input voltage, and the first module M#1 itself does not have IVS control ring, the IVS ring of other all modules directly controls to be added rear negate by it, join in the Duty ratio control of oneself, do like this and just make the total contribution of whole IVS ring to system output duty cycle be 0, thus the control of output voltage can not be affected, make IVS ring and double-loop control decoupling zero; Other module I VS ring control block diagrams except module 1 as shown in Figure 4, f in Fig. 4 _spfor input voltage sample frequency.G _vcdfor IVS ring compensation tache, A (s) ring is the transfer function between input voltage and control signal.

Step S2, determines the impact of communication system on control strategy:

As shown in Figure 5, identical with IPOS, the first module M#1 is responsible for the control task of output-voltage loop to the specific implementation of whole ISOP three close-loop control system under ring communication construction, and its output is as unified input current ring reference input I _ref, be sent to other modules, i _pfor transformer primary electric current.V _sumbe used for the input voltage V that each module is recorded _cdiadd up, to obtain the input voltage of whole system. being used for cumulative each exports from the control of module input grading ring, and as primary module input Pressure and Control amount after negate, primary module itself does not have IVS control ring.

For the impact of double-loop control by communication delay, in ISOP changer system, the reference voltage of other modules is sended over by the first module, in this process, there is communication delay, the delay of disparate modules is different, for the impact of double-loop control by communication delay, get the delay that this delay is N module, namely

$T_d=\frac{N-1}{N}{T}_C$ (formula 1);

In formula 1: T _dfor communication delay, T _cfor the sampling period, the delay of N module is maximum delay situation, all reaches stable in maximum delay situation, and the situation being so less than this delay is also all stable;

Refer to Fig. 6, the effect diagram that communication delay controls primary module IVS, IVS ring in other modules except the first module does not affect by communication delay, it is all local measurement, local to control, but do not have IVS ring due to primary module, it is that the control of other module I VS rings is exported cumulative negate, so the IVS of primary module controls the impact by communication delay, its delay is just a complete communication cycle.

By the ISOP changer system IVS ring schematic diagram of Fig. 4, learn

$-\underset{i=2}{\overset{N}{\Σ}}{x}_i=-\underset{i=2}{\overset{N}{\Σ}}{K}_{vc}(\frac{{\hat{v}}_{in}}{N}-{\hat{v}}_{cdi})G_{vcd}{e}^{\frac{-s}{2f_{sp}}}=(\frac{{\hat{v}}_{in}}{N}-{\hat{v}}_{cd1})K_{vc}{e}^{\frac{-s}{2f_{sp}}}{G}_{VCd}$

The communication delay of Fig. 6 is equivalent to Fig. 7 to the effect diagram that primary module IVS controls, and namely equivalent primary module IVS controls schematic diagram.

Step S3, design compensation link, comprises the following steps:

S31, the first compensation of design current inner ring, the loop gain Γ of current inner loop _currentfor:

${\mathrm{\Γ}}_{current}=K_{CC}\·G_i\·G_{id}\·LPF\·\frac{1}{F_m}\·\exp (-\frac{s}{2f_{sp}})$ (formula 2);

In formula 2: K _cCfor current measurement conversion coefficient; G _ifor current loop control compensates transfer function; G _idfor transformer primary electric current is to the transfer function of duty ratio; LPF is average current low pass filter; F _mfor PWM carrier amplitude; f _spfor current sample frequency;

Then by whole current inner loop, when integrally, its closed loop transfer function, G is calculated:

$G=\frac{G_i}{F_m(1+{\mathrm{\Γ}}_{current})}$ (formula 3);

By MATLAB, draw the Bode diagram of electric current loop before compensation and after compensating, after compensating, the increase of low frequency range obviously increases;

Get before and after compensating, electric current loop Bode diagram as shown in Figure 8, by compensating, adds the gain in low frequency district, cuts joint frequency simultaneously and increase to 14.2kHz, phase margin 22.6 degree.

S32, finally obtains the loop gain Γ of whole outer voltage _voltage:

${\mathrm{\Γ}}_{voltage}=K_{VC}\·G_V\·G\·G_{vd}\exp (-\frac{s}{2f_r}-T_{d}s)$ (formula 4);

In formula 4, K _vCfor voltage measurement conversion coefficient; G _vfor Voltage loop control and compensation transfer function; G _vdfor output voltage is to the transfer function of duty ratio; T _dfor communication delay, f _rit is maximum equivalent sample frequency; G is the closed loop transfer function, of whole current inner loop;

In outer voltage, communication delay T _dbe dominating delay, refer step S2, rounds a circular communication maximum delay, namely

$T_d=\frac{N-1}{N}{T}_C=\frac{N-1}{{\mathrm{Nv}}_c}$ (formula 5);

In formula 5, v _cfor communication speed.

First be still and do not add compensation tache, draw the bode curve of one group of performance communication speed and maximum bandwidth relation, as shown in Figure 9, as can be seen from the figure at v _c=4kHz, when frequency is 1kHz, gain is-39.3dB.Therefore G is designed _v=92.Before and after compensating, Voltage loop Bode diagram as shown in Figure 10, and after compensating as seen from Figure 10, Voltage loop shearing frequency is 1kHz, and phase margin is 25.1 degree.100Hz place loop gain is 20.3dB, substantially meets control overflow.

S33, for the IVS ring of primary module, its loop gain Γ _iVSfor:

${\mathrm{\Γ}}_{IVS}=K_{vc}\exp \left(\frac{-s}{2f_{sp}}\right)G_{vcd}\exp (-T_{C}s)\frac{1}{F_m}A\left(s\right)$ (formula 6);

In formula 6, K _vCfor voltage measurement conversion coefficient, F _mfor PWM carrier amplitude; G _vcdfor IVS ring compensation tache; f _spfor current sample frequency, T _cfor the sampling period, the IVS ring low-frequency gain after compensation significantly improves.

Still adopt identical with method for designing when analyzing dicyclo, do not add compensation tache G _vcd, adopt different communication speed v _c, draw one group of bode curve, as shown in figure 11, IVS ring is the slower ring of a control rate, and specific output Voltage loop is also slow, at v _cduring=4kHz, its maximum bandwidth is no more than 700Hz.But because its input is direct current, maximum interference comes from power frequency, and therefore shearing frequency is positioned at 500Hz.When can obtain 500Hz by figure, IVS loop gain is-12.3dB.Design for this reason as shown in figure 12, the IVS ring low-frequency gain after compensating in Figure 12 significantly improves IVS ring Bode diagram before and after compensating, and shearing frequency is 510Hz, and phase margin is 18 degree.The IVS ring of other modules, owing to there is not communication delay, so its shearing frequency is by larger than primary module many.

The control method of ISOP changer system of the present invention, adopt three close-loop control strategy, three rings comprise output-voltage loop, input current ring and IVS ring, three close-loop control strategy is that output-voltage loop and input current ring double-loop control and IVS ring control, take into full account the impact of communication system on three close-loop control strategy, and add compensation tache design, the net synchronization capability of each module can be ensured, extraordinary voltage and current characteristic can be obtained, use three close-loop control strategy, can guarantee to rush to repair the reliable and stable of the transmission of electricity quality of power supply.

Above embodiment is used for illustrative purposes only, but not limitation of the present invention, person skilled in the relevant technique, without departing from the spirit and scope of the present invention, various conversion or modification can also be made, therefore all equivalent technical schemes also should belong to category of the present invention, should be limited by each claim.

Claims (1)

1. a control method for ISOP changer system, described ISOP changer system is connected at input side by multiple module, outlet side parallel combination forms, and it is characterized in that, described control method comprises the following steps:

Step S1, determine control strategy: adopt three close-loop control strategy, three rings comprise output-voltage loop, input current ring and IVS ring, the control of output-voltage loop and the control composition double-loop control of input current ring, i.e. outer voltage and average current inner loop Double-loop Control Strategy, the control of outer voltage exports the reference input as current inner loop, is DC/DC conversion, input voltage fluctuation is very little, and transformer primary electric current equals module input current; The control of IVS ring is completely distributed, except the first module, other each modules are the input voltage that reference value regulates oneself according to the mean value of input voltage, and the first module itself does not have IVS control ring, the IVS ring of other all modules directly controls to be added rear negate by it, joins in the Duty ratio control of oneself, does like this and just make the total contribution of whole IVS ring to system output duty cycle be 0, thus the control of output voltage can not be affected, make IVS ring and double-loop control decoupling zero;

Step S2, determine the impact of communication system on control strategy: in ISOP changer system, the reference voltage of other modules is sended over by the first module, in this process, there is communication delay, the delay of disparate modules is different, for the impact of double-loop control by communication delay, get the delay that this delay is N module, namely

$T_d=\frac{N-1}{N}{T}_C$ (formula 1);

In formula 1: T _dfor communication delay, T _cfor the sampling period, the delay of N module is maximum delay situation, all reaches stable in maximum delay situation, and the situation being so less than this delay is also all stable;

Cumulative each exports from the control of module input grading ring, and as primary module input Pressure and Control amount after negate, primary module itself does not have IVS control ring;

IVS ring in other modules except the first module does not affect by communication delay, be all local measurement, local control, but there is no IVS ring due to primary module, it the control of other module I VS rings is exported cumulative negate, so the IVS of primary module controls the impact by communication delay;

Step S3, design compensation link, comprises the following steps:

S31, the first compensation of design current inner ring, the loop gain Γ of current inner loop _currentfor:

${\mathrm{\Γ}}_{current}=K_{CC}\·G_i\·G_{id}\·LPF\·\frac{1}{F_m}\·\exp (-\frac{s}{2f_{sp}})$ (formula 2);

In formula 2: K _cCfor current measurement conversion coefficient; G _ifor current loop control compensates transfer function; G _idfor transformer primary electric current is to the transfer function of duty ratio, LPF is average current low pass filter; F _mfor PWM carrier amplitude; f _spfor current sample frequency;

Then by whole current inner loop, when integrally, its closed loop transfer function, G is calculated:

$G=\frac{G_i}{F_m(1+{\mathrm{\Γ}}_{current})}$ (formula 3);

By MATLAB, draw the Bode diagram of electric current loop before compensation and after compensating, after compensating, the increase of low frequency range obviously increases;

S32, finally obtains the loop gain Γ of whole outer voltage _voltage:

${\mathrm{\Γ}}_{voltage}=K_{VC}\·G_V\·G\·G_{vd}\exp (-\frac{s}{2f_r}-T_{d}s)$ (formula 4);

In formula 4, K _vCfor voltage measurement conversion coefficient; G _vfor Voltage loop control and compensation transfer function; G _vdfor output voltage is to the transfer function of duty ratio; T _dfor communication delay, f _rit is maximum equivalent sample frequency; G is the closed loop transfer function, of whole current inner loop;

In outer voltage, communication delay T _dbe dominating delay, refer step S2, rounds a circular communication maximum delay, namely

$T_d=\frac{N-1}{N}{T}_C=\frac{N-1}{{\mathrm{Nv}}_c}$ (formula 5);

In formula 5, v _cfor communication speed;

S33, for the IVS ring of primary module, its loop gain Γ _iVSfor:

${\mathrm{\Γ}}_{IVS}=K_{vc}\exp \left(\frac{-s}{2f_{sp}}\right)G_{vcd}\exp (-T_{C}s)\frac{1}{F_m}A\left(s\right)$ (formula 6);

In formula 6, K _vCfor voltage measurement conversion coefficient, F _mfor PWM carrier amplitude; G _vcdfor IVS ring compensation tache; f _spfor current sample frequency, T _cfor the sampling period, the IVS ring low-frequency gain after compensation significantly improves.