CN103036286A - Safe charge-discharge control method of all-vanadium redox flow battery comprising direct current / direct current (DC / DC) converter - Google Patents

Abstract

The invention provides a safe charge-discharge control method of an all-vanadium redox flow battery (VRB) comprising a direct current / direct current (DC / DC) converter. According to the control method, the VRB group cascade bi-directional DC / DC converter is adopted as a charge-discharge port, wherein an inner ring of the DC / DC converter is controlled by a VRB side inductor average current, an outer ring of the DC / DC converter is a double closed-loop strategy which is constant in power, constant in voltage, and controlled by trickle switch, and a corresponding three-stage safe charge-discharge control mode is proposed with the state of charge (SOC) of the VRB and the terminal voltage limiting value as constraint condition. According to the control method, the safe charge-discharge control mode of the battery comprising the converter is considered, flexible safe charge-discharge control mode switch can be achieved by controlling the DC/ DC converter, phenomena of over-charging and over-discharging of the battery are effectively prevented by means of the stage type charge-discharge control method, and damage of the battery caused by over-high charging voltage or over-low discharging voltage is prevented.

Description

A kind of safe charge/discharge control method of all-vanadium flow battery that contains the DC/DC converter

Technical field

The invention belongs to battery energy storage and discharge and recharge the control technology field, be particularly related to the control method that a kind of all-vanadium flow battery of the DC/DC of containing converter discharges and recharges safely, comprise that specifically the safety when considering charge state of all-vanadium redox flow battery and terminal voltage limit value constraints discharges and recharges the control method of switch mode.

Background technology

Along with the extensive batch (-type) energy is incorporated into the power networks, its distinctive fluctuation and randomness have been brought impact to the safe and stable operation of electrical network, and energy storage technology is one of effective means that addresses these problems.Wherein the electrochemical energy storage mode is used comparatively extensive, but in actual motion, carry out energy exchange by converter between battery and the load, its control mode directly affects battery performance and useful life, this will the changes persuing parallel operation not only has tradition and discharges and recharges the control function, but also need to satisfy the requirement of cell safety stable operation, fast charging and discharging response and instantaneous high-power output.

The all-vanadium flow battery energy storage is simple in structure with it, repeating charge and discharge process can not cause under the battery capacity degradation advantage just progressively to be used, but the existing situation that its research that discharges and recharges mostly is confined to VRB body angle, and in actual applications, carry out energy exchange by converter between battery and the load, but do not consider in the most charge/discharge control method that the cell safety that contains converter discharges and recharges control model.To how considering that the control strategy research under the safe and reliable operation constraint of VRB own relates to less.Will have a strong impact on the useful life of battery or cause permanent damage in case battery charge state or outer end voltage exceed the limit value that can bear, thereby jeopardize the safe and stable operation of whole energy-storage system.Therefore, all-vanadium flow battery how to consider to contain the DC/DC converter discharges and recharges safely control and has important practical significance.

Summary of the invention

In view of this, technical problem to be solved by this invention provides the control method that a kind of all-vanadium flow battery of the DC/DC of containing converter discharges and recharges safely, can avoid overcharging, crossing and put the phenomenon generation of battery, and prevent that charging voltage is too high or too low and cause the damage of battery, improve the security reliability of battery.

The object of the present invention is achieved like this:

The control method that the all-vanadium flow battery of a kind of DC/DC of containing converter provided by the invention discharges and recharges safely may further comprise the steps:

S1: detect VRB outer end actual voltage signal U _b, the actual current signal I of VRB side inductance _L

S2: with the VRB outer end actual voltage signal U that detects _bWith VRB side inductance actual current signal I _LMultiply each other, obtain VRB actual electric power signal P _Battery

S3: with set value of the power P _Ref, current setting value I _Ref, voltage setting value U _RefRespectively with VRB actual electric power signal P _Battery, actual current signal I _L, actual voltage signal U _bDiffer from, difference is input to discharges and recharges in the handover module, and select different charge and discharge modes according to switching command, when needs charge, enter step S4 and charge; When needs discharge, enter step S5 and discharge;

S4: when charging, detect VRB terminal voltage U _bValue is in discharge voltage lower limit U _LowWith charging voltage upper limit U _HighBetween the time, with set value of the power P _RefEqual charge power set point P _ChargeCarry out permanent power quick charge to VRB;

This moment, detect the real-time state-of-charge SOC signal of VRB and the actual voltage signal U that charges and discharge of outer end of VRB _b, when detecting the actual voltage signal U that charges and discharge of VRB outer end _bWhen exceeding limit value and SOC value when not exceeding limit value, transfer voltage setting value U to _RefEqual upper voltage limit U _HighCharge, the SOC signal will continue rising this moment, until it is worth when out-of-limit, transfer current setting value I to _RefTrickle I equals to charge _MinCharge, finish safe charging control;

S5: when discharge, detect VRB terminal voltage U _bValue is in discharge voltage lower limit U _LowWith charging voltage upper limit U _HighBetween the time, with set value of the power P _RefEqual discharge power set point P _DischargeCarry out permanent power repid discharge to VRB;

At this moment, detect the real-time state-of-charge SOC signal of VRB and the actual voltage signal U that charges and discharge of outer end of VRB _bIf the SOC signal is not out-of-limit, and the actual voltage signal U that charges and discharge of VRB outer end _bBe lower than under the discharge voltage and prescribe a time limit, transfer voltage setting value U to _RefEqual lower voltage limit value U _LowDischarge, the SOC signal will continue reduction this moment, until it is worth when out-of-limit, transfer current setting value I to _RefTrickle I equals to discharge _MinDischarge, finish safe-discharge control;

S6: according to the power charge and discharge mode of selecting with set value of the power P _RefWith VRB actual electric power signal P _BatteryDiffer from, or according to the trickle charge and discharge mode of selecting with current setting value I _RefWith VRB side inductance actual current signal I _LDiffer from, or according to the voltage charge mode of selecting with voltage setting value U _RefWith VRB outer end actual voltage signal U _bDiffer from, obtain the given value of current signal by processing this difference, again with the actual current signal I of VRB side inductance _LDiffer from, and obtain the control voltage signal by the difference that again draws, described control voltage signal is controlled conducting and the shutoff of IGBT circuit in the DC/DC converter after treatment;

S7: repetitive cycling step S1-S6.

Further, the switching condition that discharges and recharges switch mode among the step S3 is: as VRB terminal voltage signal U _bMore than or equal to its charging upper limit voltage U _HighDuring value, battery VRB switches to constant voltage charge, less than its discharge lower voltage limit U _LowDuring value, battery VRB transfers constant voltage discharge to; When the state-of-charge SOC of VRB value more than or equal to 0.8 the time, transfer trickle charge to, less than or equal to 0.2 o'clock, transfer trickle discharge to.

Further, the control of the safe charging described in step S4 set-point expression formula is:

$\left\{\begin{array}{cc}{P}_{\mathrm{ch}\arg e}=P_{\mathrm{ref}}& U_{\mathrm{low}}<U_b<U_{\mathrm{high}}\\ U_{\mathrm{ch}\arg e}=U_{\mathrm{ref}}=U_{\mathrm{high}}& U_b\&GreaterEqual;U_{\mathrm{high}}\\ I_{\mathrm{ref}}=I_{\min }& \mathrm{SOC}\&GreaterEqual;0.8\end{array}\right.$

In the formula, P _ChargeBe the battery charge power; U _ChargeBe battery charging voltage; I _MinBe charging trickle electric current; U _HighBe the charging voltage higher limit.

Further, the control of the safe-discharge described in step S5 set-point expression formula is:

$\left\{\begin{array}{cc}{P}_{\mathrm{disch}\arg e}=P_{\mathrm{ref}}& U_{\mathrm{low}}<U_b<U_{\mathrm{high}}\\ U_{\mathrm{disch}\arg e}=U_{\mathrm{ref}}=U_{\mathrm{low}}& U_b\&le;U_{\mathrm{low}}\\ I_{\mathrm{ref}}=-I_{\min }& \mathrm{SOC}\&le;0.2\end{array}\right.$

In the formula, P _DischargeBe battery discharge power; U _AischargeBe battery discharge voltage; I _MinBe discharge trickle electric current; U _LowBe the charging voltage higher limit.

Further, to obtain the given value of current signal be that passing ratio integrator PI carries out to the difference of passing through among the described step S6; Described by the difference that again draws obtain control voltage signal be that passing ratio integral PI device carries out; Described control voltage signal after treatment controlled voltage signal is modulated formation through PWM.

The invention has the advantages that: the safe charge/discharge control method of the all-vanadium flow battery of a kind of DC/DC of containing converter disclosed by the invention, be VRB side inductance Average Current Control by interior ring, outer shroud is the two closed loop strategies of the DC/DC converter of permanent power, constant current and constant voltage switching controls, and take VRB state-of-charge and terminal voltage limit value as constraints, three stages that proposed in battery charge and discharge process discharge and recharge safely control model.When detecting the VRB terminal voltage and exceed its charging upper limit voltage, transfer constant voltage charge to, prevented effectively that then the too high battery that causes of charging voltage from damaging, SOC continues to rise, when exceeding limit value, battery charge state SOC transfers trickle charge to when detecting, reduce the redox reaction speed of VRB, effectively prevented the generation of over-charging of battery phenomenon.Be lower than under the discharge voltage in limited time when detecting the VRB terminal voltage, transfer constant voltage discharge to, SOC then continues to reduce, and detects to transfer trickle discharge to when out-of-limit, then effectively prevent discharge voltage cross low or cross put phenomenon to battery cause badly damaged.This control method can be guaranteed the all-vanadium flow battery safe and stable operation, prolongs its useful life.

Description of drawings

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is described in further detail below in conjunction with accompanying drawing, wherein:

Fig. 1 is the control block diagram that discharges and recharges that the all-vanadium flow battery group connects two-way DC/DC converter;

Fig. 2 is the design sketch that all-vanadium flow battery discharges and recharges safely control, when VRB in initial state-of-charge SOC=0.35 situation, with constant power charge, adopt the VRB operation characteristic figure under the safe charging pattern;

Fig. 3 is the design sketch that all-vanadium flow battery discharges and recharges safely control, as the initial state-of-charge SOC=0.65 of VRB, with the firm power discharge, adopts the VRB operation characteristic figure under the safe-discharge pattern.

Embodiment

Below with reference to accompanying drawing, the preferred embodiments of the present invention are described in detail; Should be appreciated that preferred embodiment only for the present invention is described, rather than in order to limit protection scope of the present invention.

Embodiment 1

Fig. 1 is the control block diagram that discharges and recharges that the all-vanadium flow battery group connects two-way DC/DC converter, and as shown in the figure: the control method that the all-vanadium flow battery of a kind of DC/DC of containing converter provided by the invention discharges and recharges safely may further comprise the steps:

S1: detect VRB outer end actual voltage signal U _b, the actual current signal I of VRB side inductance _L

S2: with the VRB outer end actual voltage signal U that detects _bWith VRB side inductance actual current signal I _LMultiply each other, obtain VRB actual electric power signal P _Battery

S3: with set value of the power P _Ref, current setting value I _Ref, voltage setting value U _RefRespectively with VRB actual electric power signal P _Battery, actual current signal I _L, actual voltage signal U _bDiffer from, difference is input to discharges and recharges in the handover module, and select different charge and discharge modes according to switching command, when needs charge, enter step S4 and charge; When needs discharge, enter step S5 and discharge;

The switching condition that discharges and recharges switch mode among the step S3 is: as VRB terminal voltage signal U _bMore than or equal to its charging upper limit voltage U _HighDuring value, battery VRB switches to constant voltage charge, less than its discharge lower voltage limit U _LowDuring value, battery VRB transfers constant voltage discharge to.When the state-of-charge SOC of VRB value more than or equal to 0.8 the time, transfer trickle charge to, less than or equal to 0.2 o'clock, transfer trickle discharge to.

S4: when charging, detect VRB terminal voltage U _bValue is in discharge voltage lower limit U _LowWith charging voltage upper limit U _HighBetween the time, with set value of the power P _RefEqual charge power set point P _ChargeCarry out permanent power quick charge to VRB;

This moment, detect the real-time state-of-charge SOC signal of VRB and the actual voltage signal U that charges and discharge of outer end of VRB _b, when detecting the actual voltage signal U that charges and discharge of VRB outer end _bWhen exceeding limit value and SOC value when not exceeding limit value, transfer voltage setting value U to _RefEqual upper voltage limit U _HighCharge, the SOC signal will continue rising this moment, until it is worth when out-of-limit, transfer current setting value I to _RefTrickle I equals to charge _MinCharge, finish safe charging control;

Safe charging control set-point expression formula described in the step S4 is:

$\left\{\begin{array}{cc}{P}_{\mathrm{ch}\arg e}=P_{\mathrm{ref}}& U_{\mathrm{low}}<U_b<U_{\mathrm{high}}\\ U_{\mathrm{ch}\arg e}=U_{\mathrm{ref}}=U_{\mathrm{high}}& U_b\&GreaterEqual;U_{\mathrm{high}}\\ I_{\mathrm{ref}}=I_{\min }& \mathrm{SOC}\&GreaterEqual;0.8\end{array}\right.$

In the formula, P _ChargeBe the battery charge power; U _ChargeBe battery charging voltage; I _MinBe charging trickle electric current; U _HighBe the charging voltage higher limit.

S5: when discharge, detect VRB terminal voltage U _bValue is in discharge voltage lower limit U _LowWith charging voltage upper limit U _HighBetween the time, with set value of the power P _RefEqual discharge power set point P _DischargeCarry out permanent power repid discharge to VRB;

At this moment, detect the real-time state-of-charge SOC signal of VRB and the actual voltage signal U that charges and discharge of outer end of VRB _bIf the SOC signal is not out-of-limit, and the actual voltage signal U that charges and discharge of VRB outer end _bBe lower than under the discharge voltage and prescribe a time limit, transfer voltage setting value U to _RefEqual lower voltage limit value U _LowDischarge, the SOC signal will continue reduction this moment, until it is worth when out-of-limit, transfer current setting value I to _RefTrickle I equals to discharge _MinDischarge, finish safe-discharge control;

S6: according to the power charge and discharge mode of selecting with set value of the power P _RefWith VRB actual electric power signal P _BatteryDiffer from, or according to the trickle charge and discharge mode of selecting with current setting value I _RefWith VRB side inductance actual current signal I _LDiffer from, or according to the voltage charge mode of selecting with voltage setting value U _RefWith VRB outer end actual voltage signal U _bDiffer from, obtain the given value of current signal by processing this difference, again with the actual current signal I of VRB side inductance _LDiffer from, and obtain the control voltage signal by the difference that again draws, described control voltage signal is controlled conducting and the shutoff of IGBT circuit in the DC/DC converter after treatment; Safe-discharge control set-point expression formula described in the step (5) is:

$\left\{\begin{array}{cc}{P}_{\mathrm{disch}\arg e}=P_{\mathrm{ref}}& U_{\mathrm{low}}<U_b<U_{\mathrm{high}}\\ U_{\mathrm{disch}\arg e}=U_{\mathrm{ref}}=U_{\mathrm{low}}& U_b\&le;U_{\mathrm{low}}\\ I_{\mathrm{ref}}=-I_{\min }& \mathrm{SOC}\&le;0.2\end{array}\right.$

In the formula, P _DischargeBe battery discharge power; U _DischargeBe battery discharge voltage; I _MinBe discharge trickle electric current; U _LowBe the charging voltage higher limit.

To obtain the given value of current signal be that passing ratio integrator PI carries out to the difference of passing through among the described step S6; Described by the difference that again draws obtain control voltage signal be that passing ratio integral PI device carries out; Described control voltage signal after treatment controlled voltage signal is modulated formation through PWM.

S7: repetitive cycling step S1-S6.

Embodiment 2

The difference of present embodiment and embodiment 1 only is:

As shown in Figure 1, device among the embodiment provided by the invention, comprise the two-way DC/DC converter that discharges and recharges handover module, PWM generator, proportional integral device PI, is provided with the IGBT circuit, and the VRB of many series connection group, the two-way DC/DC converter of cascade complementary type PWM, wherein ring is VRB side inductance Average Current Control in the DC/DC converter using, and outer shroud is the double-loop control strategy of permanent power, constant current and constant voltage switching controls.Detect respectively VRB outer end voltage signal U by the voltage and current transducer _bWith VRB side inductance average current signal I _L, and then obtain the actual power signal P that discharges and recharges of battery _BatteryFor:

P _battety＝U _b×I _L （1）

Simultaneously with voltage signal U _bSignal as the actual charging/discharging voltage of VRB; With current signal I _LSignal as actual VRB trickle charging and discharging currents.With power, electric current, voltage setting value P _Ref, I _Ref, U _RefRespectively with actual power, electric current, the voltage signal P of discharging and recharging of battery _Battery, U _b, I _LDiffer from, its difference enters by three group selection switches and discharges and recharges handover module, waits for that switching command sends the different charge and discharge mode of selection.When charging, detect VRB terminal voltage U _bValue is in discharge voltage lower limit U _LowWith charging voltage upper limit U _HighBetween the time, with set value of the power P _RefEqual charge power set point P _ChargeCarry out permanent power quick charge to VRB.This moment, detect real-time state-of-charge (SOC) signal of VRB and the outer end voltage signal U of VRB _b, when detecting the VRB terminal voltage and exceed its charging upper limit voltage and SOC and do not exceed limit value, then transfer voltage setting value U to _RefEqual the charging upper limit voltage U _HighCharge, selector switch switches to the constant voltage charge pattern, and this moment, SOC continued to rise, and when the state-of-charge SOC value that detects VRB exceeds limit value 0.8, transferred current setting value I to _RefTrickle I equals to charge _MinCharge, selector switch switches to the trickle charge pattern; Control and finish safe charging.Then safe charging control set-point expression formula is:

$\left\{\begin{array}{cc}{P}_{\mathrm{ch}\arg e}=P_{\mathrm{ref}}& U_{\mathrm{low}}<U_b<U_{\mathrm{high}}\\ U_{\mathrm{ch}\arg e}=U_{\mathrm{ref}}=U_{\mathrm{high}}& U_b\&GreaterEqual;U_{\mathrm{high}}\\ I_{\mathrm{ref}}=I_{\min }& \mathrm{SOC}\&GreaterEqual;0.8\end{array}\right.---\left(2\right)$

When discharge, detect VRB terminal voltage U _bValue is in discharge voltage lower limit U _LowWith charging voltage upper limit U _HighBetween the time, with set value of the power P _RefEqual discharge power set point P _DischargeMake VRB carry out permanent power discharge.At this moment, detect real-time state-of-charge (SOC) signal of VRB and the outer end voltage signal U of VRB _bIf SOC is not out-of-limit, and the VRB terminal voltage is lower than under the discharge voltage in limited time, transfers voltage setting value U to _RefEqual lower voltage limit value U _LowDischarge, SOC will continue reduction this moment, until it is worth when out-of-limit, transfer current setting value I to _RefTrickle I equals to discharge _MinDischarge, finish the safe-discharge control of three stages.Then safe-discharge control set-point expression formula is:

$\left\{\begin{array}{cc}{P}_{\mathrm{disch}\arg e}=P_{\mathrm{ref}}& U_{\mathrm{low}}<U_b<U_{\mathrm{high}}\\ U_{\mathrm{disch}\arg e}=U_{\mathrm{ref}}=U_{\mathrm{low}}& U_b\&le;U_{\mathrm{low}}\\ I_{\mathrm{ref}}=-I_{\min }& \mathrm{SOC}\&le;0.2\end{array}\right.---\left(3\right)$

And then poor according to charge and discharge mode value of being set of selecting and actual value, its difference passing ratio integration (PI) device obtains the given value of current signal, with battery side inductance average current signal I _LDiffer from, the controlled voltage signal of its difference passing ratio integration (PI) device is through conducting and the shutoff of IGBT in the two-way DC/DC converter of control after the PWM modulation.

Because all-vanadium flow battery is in charge and discharge process, battery charge state or outer end voltage may exceed the limits that can bear, can have a strong impact on like this useful life of battery or cause permanent damage, thereby jeopardize the safe and stable operation of whole energy-storage system.By control DC/DC converter, with charge state of all-vanadium redox flow battery SOC and outer end voltage U _bBe constraints, corresponding safety be set discharge and recharge switch mode, avoid super-charge super-discharge and voltage out-of-limit phenomenon to occur, improve the cell safety reliability service.

Adopt the method for the invention, the safety of VRB being carried out firm power discharges and recharges experiment, and its result is shown in Fig. 2,3.

The VRB terminal voltage reaches charging upper limit voltage 64V constantly at 9235s as can be seen from Figure 2, switches at once the 64V constant voltage charge, thereby prevents that the VRB charging voltage is too high, causes battery to damage; This moment, SOC continued to rise, and at 10650s constantly, SOC rises to 0.8, at this moment, switch charge mode and transfer trickle charge to, simultaneously, VRB terminal voltage magnitude of voltage after switching to the trickle charge control model descends to some extent, and this is because after adopting trickle charge, the internal resistance dividing potential drop of VRB reduces.As can be seen from Figure 3, when the 8409s battery terminal voltage is lower than discharge voltage lower limit 40V, transfer constant voltage discharge to, keeping the VRB terminal voltage is 40V, and SOC will continue to descend this moment, and SOC drops to 0.2 when 1065s, and this moment, the switching controls pattern transferred trickle discharge to.Having prevented from putting phenomenon occurs.

Can find out from experimental result picture, discharge and recharge switching control strategy constraints with VRB state-of-charge and terminal voltage as safety, adopt three stage charge and discharge modes, can make VRB work in the safe and stable operation zone, help to prolong battery.

The above is the preferred embodiments of the present invention only, is not limited to the present invention, and obviously, those skilled in the art can carry out various changes and modification and not break away from the spirit and scope of the present invention the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.

Claims (5)

1. control method that the all-vanadium flow battery that contains the DC/DC converter discharges and recharges safely is characterized in that: may further comprise the steps:

S1: detect VRB outer end actual voltage signal U _b, the actual current signal I of VRB side inductance _L

S2: with the VRB outer end actual voltage signal U that detects _bWith VRB side inductance actual current signal I _LMultiply each other, obtain VRB actual electric power signal P _Battery

S3: with set value of the power P _Ref, current setting value I _Ref, voltage setting value U _RefRespectively with VRB actual electric power signal P _Battery, actual current signal I _L, actual voltage signal U _bDiffer from, difference is input to discharges and recharges in the handover module, and select different charge and discharge modes according to switching command, when needs charge, enter step S4 and charge; When needs discharge, enter step S5 and discharge;

S4: when charging, detect VRB terminal voltage U _bValue is in discharge voltage lower limit U _LowWith charging voltage upper limit U _HighBetween the time, with set value of the power P _RefEqual charge power set point P _ChargeCarry out permanent power quick charge to VRB;

This moment, detect the real-time state-of-charge SOC signal of VRB and the actual voltage signal U that charges and discharge of outer end of VRB _b, when detecting the actual voltage signal U that charges and discharge of VRB outer end _bWhen exceeding limit value and SOC value when not exceeding limit value, then transfer voltage setting value U to _RefEqual upper voltage limit U _HighCharge, the SOC signal will continue rising this moment, until it is worth when out-of-limit, transfer current setting value I to _RefTrickle I equals to charge _MinCharge, finish safe charging control;

S5: when discharge, detect VRB terminal voltage U _bValue is in discharge voltage lower limit U _LowWith charging voltage upper limit U _HighBetween the time, with set value of the power P _RefEqual discharge power set point P _DischargeCarry out permanent power repid discharge to VRB;

At this moment, detect the real-time state-of-charge SOC signal of VRB and the actual voltage signal U that charges and discharge of outer end of VRB _bIf the SOC signal is not out-of-limit, and the actual voltage signal U that charges and discharge of VRB outer end _bBe lower than under the discharge voltage and prescribe a time limit, transfer voltage setting value U to _RefEqual lower voltage limit value U _LowDischarge, the SOC signal will continue reduction this moment, until it is worth when out-of-limit, transfer current setting value I to _RefTrickle I equals to discharge _MinDischarge, finish safe-discharge control;

S6: according to the power charge and discharge mode of selecting with set value of the power P _FefWith VRB actual electric power signal P _BatteryDiffer from, or according to the trickle charge and discharge mode of selecting with current setting value I _RefWith VRB side inductance actual current signal I _LDiffer from, or according to the voltage charge and discharge mode of selecting with voltage setting value U _RefWith VRB outer end actual voltage signal U _bDiffer from, obtain the given value of current signal by processing this difference, again with the actual current signal I of VRB side inductance _LDiffer from, and obtain the control voltage signal by the difference that again draws, described control voltage signal is controlled conducting and the shutoff of IGBT circuit in the DC/DC converter after treatment;

S7: repetitive cycling step S1-S6.

2. contain as claimed in claim 1 the control method that the all-vanadium flow battery of DC/DC converter discharges and recharges safely, it is characterized in that: the switching condition that discharges and recharges switch mode among the step S3 is: as VRB terminal voltage signal U _bMore than or equal to its charging upper limit voltage U _HighDuring value, battery VRB switches to constant voltage charge, less than its discharge lower voltage limit U _LowDuring value, battery VRB transfers constant voltage discharge to; When the state-of-charge SOC of VRB value more than or equal to 0.8 the time, transfer trickle charge to, less than or equal to 0.2 o'clock, transfer trickle discharge to.

3. contain as claimed in claim 1 the control method that the all-vanadium flow battery of DC/DC converter discharges and recharges safely, it is characterized in that: the safe charging control set-point expression formula described in the step S4 is:

$\left\{\begin{array}{cc}{P}_{\mathrm{ch}\arg e}=P_{\mathrm{ref}}& U_{\mathrm{low}}<U_b<U_{\mathrm{high}}\\ U_{\mathrm{ch}\arg e}=U_{\mathrm{ref}}=U_{\mathrm{high}}& U_b\&GreaterEqual;U_{\mathrm{high}}\\ I_{\mathrm{ref}}=I_{\min }& \mathrm{SOC}\&GreaterEqual;0.8\end{array}\right.$

In the formula, P _ChargeBe the battery charge power; U _ChargeBe battery charging voltage; I _MinBe charging trickle electric current; U _HighBe the charging voltage higher limit.

4. contain as claimed in claim 1 the control method that the all-vanadium flow battery of DC/DC converter discharges and recharges safely, it is characterized in that: the safe-discharge control set-point expression formula described in the step S5 is:

$\left\{\begin{array}{cc}{P}_{\mathrm{disch}\arg e}=P_{\mathrm{ref}}& U_{\mathrm{low}}<U_b<U_{\mathrm{high}}\\ U_{\mathrm{disch}\arg e}=U_{\mathrm{ref}}=U_{\mathrm{low}}& U_b\&le;U_{\mathrm{low}}\\ I_{\mathrm{ref}}=-I_{\min }& \mathrm{SOC}\&le;0.2\end{array}\right.$

In the formula, P _DischargeBe battery discharge power; U _DischargeBe battery discharge voltage; I _MinBe discharge trickle electric current; U _LowBe the charging voltage higher limit.

5. contain as claimed in claim 1 the control method that the all-vanadium flow battery of DC/DC converter discharges and recharges safely, it is characterized in that: to obtain the given value of current signal be that passing ratio integrator PI carries out to the difference of passing through among the described step S6; Described by the difference that again draws obtain control voltage signal be that passing ratio integral PI device carries out; Described control voltage signal after treatment controlled voltage signal is modulated formation through PWM.

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