CN106655781A - LCC resonant converter PWM phase shift mixed control and efficiency optimization method - Google Patents

Abstract

The invention discloses an LCC resonant converter PWM phase shift mixed control and efficiency optimization method. The method comprises the following steps: carrying out sampling on output voltage of a converter, obtaining voltage difference between an output voltage sample value and a reference value and serving the voltage difference as the input of a voltage regulator, and obtaining an output value c; carrying out sampling on resonance current of the converter, and carrying out optimization algorithm to obtain two coefficients k1 and k2; carrying out calculation and correction on the output instruction value c of the voltage regulator through the coefficients k1 and k2 to obtain two instruction values, that is, phase shifting angle theta and duty ratio d, of the PWM phase shift mixed control method; and inputting the phase shifting angle and the duty ratio instruction values to a PWM phase shift mixed modulator to obtain driving signals of four switching tubes at a primary side of the resonant converter. The method improves control freedom degree of the converter; and under the condition of maintaining specific output power invariant and ensuring ZVS realization, the resonance current is allowed to be minimum by adjusting the coefficients and changing combination of control variables, and efficiency of the converter is improved.

Description

A kind of LCC controlled resonant converters PWM phase shifts mixing control and efficiency optimization method

Technical field

The present invention relates to electric and electronic technical field, and in particular to a kind of LCC controlled resonant converters PWM phase shifts mixing control and Efficiency optimization method.

Background technology

High frequency is one of development trend of modern power electronics technology, realizes that high frequency can improve system power close Degree, reduces the weight and volume of device.Traditional PWM switch converters are all operated in and force the hard switching state for turning on and off, Due to the non-ideal characteristic of electronic power switch device, generally complete to open when voltage is not zero or be not in electric current Shut-off is completed when zero, loss is larger, it is larger to generate heat to cause switching device to cut-off.Due to switching loss and switching frequency into just Than relation, therefore when switching frequency is improved, cut-offfing loss and generating heat for switching device also can increase, or even burn out switch Device.On the other hand as the raising of switching frequency, the du/dt and di/dt of system also can be improved, serious electromagnetism is caused to do Disturb.To solve the above problems, most become reduce loss earlier than the soft switch technique at the beginning of the eighties in last century and put forward efficient necessity Means.

Controlled resonant converter is compared with traditional PWM types DC/DC changer and be easily achieved Sofe Switch, can be helped with reduce loss In high frequency development.In addition, controlled resonant converter has preferable load characteristic under load open circuit or the extreme case of short circuit, It is used widely in various fields.LCC Series- Parallel Resonant Converters have both series resonant converter and parallel resonance changer Advantage, with preferable output voltage regulating power and load short circuits protective capability.Due to LCC Series- Parallel Resonant Converter energy Enough using the parasitic parameter of high frequency transformer, as a part for resonant tank, therefore suitable for high voltagehigh frequency occasion.

Mode of resonance switch converters with operating frequency height, are lost little, efficiency high, body as one kind of Sofe Switch (ZVS) The advantages of product is little.LCC mode of resonance switch converters are had concurrently with it can realize that the ZVS of primary side switch pipe is opened in full-load range It is logical, the characteristics of the ZVS of commutation diode is turned off and it is easy to the advantages such as the integrated, wide input voltage range of magnetic, in HF switch field Obtain extensive concern and apply.

Controlled resonant converter is typically using FREQUENCY CONTROL or phase shifting control.FREQUENCY CONTROL is simple and reliable, be easily achieved, for low Rank or higher order resonances changer have broad applicability.Its shortcoming is mainly shown as：Need to adjust output switch frequency Change, can so cause significant electromagnetic compatibility problem, while increased the design difficulty of wave filter in larger scope.Phase shift Control solves the problems referred to above, and its switching frequency is constant, by adjusting Duty ratio control output voltage.Generally switching frequency is higher than Resonant frequency, now resonant network is in perception.But the problem of phase shifting control is essentially consisted in：When output is less, need to increase Plus switching frequency realizes Sofe Switch ensureing switching tube.Generally, omit to meet Sofe Switch condition configuration switch frequency More than resonant frequency.Switching frequency continues to increase reduces the power factor of resonant tank, and then causes the change of current to increase, and reduce The efficiency of controlled resonant converter.In other words, tradition phase-shifting control cannot realize Sofe Switch on a large scale.

The increase of changer resonance current can bring more conduction losses and bigger stresses of parts, cause transducer effciency Reduce.Under tradition phase-shifting control, it is conflict body to reduce resonance current and ensure that ZVS is realized, that is, optimize conduction loss and open Closing loss cannot simultaneously realize that one aspect is optimized will necessarily destroy the characteristic of other side.

The content of the invention

Goal of the invention：In order to overcome the deficiencies in the prior art, the present invention to provide a kind of LCC controlled resonant converters PWM Phase shift mixing control and efficiency optimization method, the present invention can improve the degree of freedom of control, maintain to specify output it is constant, On the premise of ensureing that ZVS is realized, realize that resonance current is minimized, improve transducer effciency.

Technical scheme：For achieving the above object, the technical solution used in the present invention is：

A kind of LCC controlled resonant converters PWM phase shifts mixing control and efficiency optimization method, including the following step that order is performed Suddenly：

Step one, the output voltage to LCC controlled resonant converters carry out sampling and obtain output voltage sampled value, by output voltage Sampled value makes the difference with reference value and obtains voltage difference, using the voltage difference for obtaining as the input of voltage regulator, obtains voltage-regulation Output order value c of device；

Step 2, the resonance current to LCC controlled resonant converters are sampled, and through optimized algorithm two correction factors are obtained k₁、k₂；

Step 3, use correction formulaCalculate and obtain phase shifting angle θ and dutycycle d this 2 command values；

Step 4, by phase shifting angle θ and dutycycle d, this 2 command values are input into PWM phase shift hybrid modulation devices, obtain the change of LCC resonance The drive signal of four switching tubes of parallel operation former limit；

In said process, the calculation process of optimized algorithm is in the step 2：

Step (1) sets k₁Initial value be 0, according to any steady state point P of LCC controlled resonant converters₀(θ₀, d₀) and repair Positive formula obtains k₂Initial value；

Step (2) is while increase k₁、k₂Value, judge k₁、k₂Phase shifting angle θ and dutycycle d after increase is to meet to update bar Part；

Step (3) updates k if update condition is met₁、k₂Value, and obtain new phase shifting angle θ and dutycycle d, and repeat Step (2), proceeds to step (4) if update condition is unsatisfactory for；

Step (4) reduces k₂Value, judge k₂Whether the phase shifting angle θ and dutycycle d after reduction meets update condition；

Step (5) terminates algorithm if condition is unsatisfactory for and exports the k before last time renewal₁、k₂Value, if condition is met Update k₂Value, and export k₁、k₂Value.

Further, in the present invention, step (2), described in (4) meet update condition be specially meet simultaneously it is following 3 conditions：

After condition (1), control variable θ, d update, the standardization output P of LCC controlled resonant converters_nFluctuation be less than The threshold value of setting；

Condition (2), the virtual value of the resonance current of LCC controlled resonant converters reduce；

Condition (3), meet Sofe Switch ZVS and realize condition：φ_vi=φ-φ_AB1≥10°；

Wherein：

φ_viFor LCC controlled resonant converter former limit output voltage V_ABWith resonance current i_rBetween phase angle；

φ is LCC controlled resonant converter equivalent circuit input impedances angle；

φ_AB1For LCC controlled resonant converter former limit output voltage V_ABFundametal compoment V_AB1Phase angle.

Further, in the present invention, tune of the PWM phase shift hybrid modulation devices to LCC controlled resonant converters in the step 4 System is carried out according to following 4 conditions：

Switching tube S2 under switching tube S1 and former limit leading-bridge on condition (1), the former limit leading-bridge of LCC controlled resonant converters Complementation conducting, the complementary conductings of switching tube S4 under switching tube S3 and former limit lagging leg on former limit lagging leg；

The dutycycle of switching tube S1 is constant on condition (2), former limit leading-bridge, is 50%；

Condition (3), triangular carrier amplitude are 1, and frequency is 2 times of switching frequencies；Triangular carrier is in k-th switch periods from 2 θ [k]/π is started counting up, and wherein θ [k] is the phase shifting angle of k-th switch periods, and k is arbitrary integer；

Switching tube S4 drive signals are low level k-th starting stage in cycle under condition (4), former limit lagging leg, In first triangular carrier rising edge when carrier wave be equal to d [k] when be turned into high level, in subsequent triangular carrier trailing edge when Upset when triangular carrier is equal to d [k] is low level, and d [k] is duty instruction value.

Further, in the present invention, in the condition (1) that update condition is related to, the standardization output of LCC controlled resonant converters Power P_nComputing formula be：

Further, in the present invention, in the condition (3), LCC controlled resonant converter equivalent input impedances angle φ and V_AB1 Angle phi_AB1Computing formula be：

Wherein：

A=C_p/C_sFor resonant capacitance ratio；C_s、C_pRespectively series and parallel resonant capacitance；

ω_sTo switch angular frequency；

ω_nFor standardization switching frequency；

α is that secondary rectification turns off angle；

I_{r_rms}For resonance current virtual value；

V_oFor output voltage.

Beneficial effect：

(1) controlled using PWM phase shifts mixing, with two controlled quentity controlled variables, improve the degree of freedom of control, make the control of changer Degree of freedom processed strengthens.

(2) adjustment factor is calculated using optimized algorithm, is maintaining to specify output constant and ensureing what ZVS was realized Under the premise of, make resonance current reach minimum by the combination of adjustment factor change controlled quentity controlled variable, improve transducer effciency.

Description of the drawings

Fig. 1 is PWM phase shift mixing control principle drawing of the present invention for LCC controlled resonant converters；

Fig. 2 is mixing control efficiency optimization method schematic diagram proposed by the present invention；

Fig. 3 is the control system block diagram of the inventive method；

Fig. 4 is the present invention for calculating adjustment factor k₁、k₂Optimized algorithm flow chart；

Fig. 5 is digital PWM phase shift hybrid modulation device schematic diagram of the present invention for LCC controlled resonant converters.

Specific embodiment

The present invention is further described below in conjunction with the accompanying drawings.

The present invention proposes a kind of LCC controlled resonant converters PWM phase shifts mixing control and efficiency optimization method, its control system frame Figure is as shown in Figure 3.Key step includes：

(1) output voltage of LCC controlled resonant converters is sampled, is made the difference with reference value and as the defeated of voltage regulator Enter, obtain exporting c；

(2) sampling is entered to the resonance current of LCC controlled resonant converters, through optimized algorithm two correction factor k is obtained₁、k₂；

(3) k is used₁、k₂Voltage regulator output order value c is calculated and corrected, PWM phase shifts mixing controlling party is obtained 2 command values of method：Phase shifting angle θ and dutycycle d；

(4) by phase shifting angle θ and dutycycle d command value input PWM phase shift hybrid modulation devices, controlled resonant converter former limit four is obtained The drive signal of individual switching tube, as shown in Figure 5.

A kind of LCC controlled resonant converters PWM phase shifts mixing control of the present invention and efficiency optimization method, its PWM phase shifts mixing Manipulator embodiment is as shown in figure 1, each switch periods is T_s, according to satisfaction, below 4 principles are carried out the modulator approach：

Switching tube S2 under switching tube S1 and former limit leading-bridge on condition (1), the former limit leading-bridge of LCC controlled resonant converters Complementation conducting, the complementary conductings of switching tube S4 under switching tube S3 and former limit lagging leg on former limit lagging leg；

The dutycycle of switching tube S1 is constant on condition (2), former limit leading-bridge, is 50%；

Condition (3), triangular carrier amplitude are 1, and frequency is 2 times of switching frequencies；Triangular carrier is in k-th switch periods from 2 θ [k]/π is started counting up, and wherein θ [k] is the phase shifting angle of k-th switch periods, and k is arbitrary integer；

Switching tube S4 drive signals are low level k-th starting stage in cycle under condition (4), former limit lagging leg, In first triangular carrier rising edge when carrier wave be equal to d [k] when be turned into high level, in subsequent triangular carrier trailing edge when Upset when triangular carrier is equal to d [k] is low level, and d [k] is duty instruction value.

As shown in Figure 1, when being controlled using PWM phase shifts proposed by the present invention mixing, LCC controlled resonant converters former limit output electricity Pressure V_ABFundametal compoment V_AB1For：

Wherein：

V_{AB1_m}And φ_AB1Respectively V_AB1Amplitude and phase angle；

V_inFor the input direct voltage of LCC controlled resonant converters.

From formula (1)：When (θ, d)=(0,0.5), i.e., S4 dutycycles are 50% and during with S1 same phases, V_{AB1_m}Reach Maximum is as follows：

Input power P of LCC controlled resonant converters_inCan be tried to achieve by below equation：

Wherein:

I_{r_m}For resonance current amplitude；

Z_inFor the equivalent circuit input impedance of LCC controlled resonant converters；

φ is LCC controlled resonant converter equivalent circuit input impedances angle.

LCC resonant converter output powers P_oFor

P_o=P_in·η (4)

Wherein：

η is the efficiency of LCC controlled resonant converters.

Formula (3) is substituted into into formula (4) can obtain LCC resonant converter output powers P_oExpression formula

Under stable situation, work as V_AB1When reaching maximum, LCC controlled resonant converters can to Load transportation peak power, therefore Output maximum is

The difference of efficiency when ignoring LCC controlled resonant converters output different capacity, then by formula (1), (5) and (6) obtaining The standardization output of LCC controlled resonant converters

For LCC controlled resonant converters, the general switching frequency that arranges is more than resonant frequency.In the situation that switching frequency is larger Under, it is ensured that all switching tubes of former limit realize that ZVS is the main path of Lifting Transform device efficiency.And all switching tubes realize ZVS's Essential condition is mainly：Before switching tube conducting, series resonance inductor is enough in order to the electric discharge of paralleled power switches electric capacity is stored Energy；In turn-on instant switching tube itself anti-paralleled diode afterflow conducting, resonance current is reverse.ZVS can be obtained with reference to Fig. 1 Realize the expression formula of condition：

Wherein：

φ_viFor LCC controlled resonant converter former limit output voltage V_ABWith resonance current i_rBetween phase angle；

φ is LCC controlled resonant converter equivalent circuit input impedances angle；

φ_AB1For LCC controlled resonant converter former limit output voltage V_ABFundametal compoment V_AB1Phase angle；

C_s、C_pRespectively series and parallel resonant capacitance；

A=C_p/C_sFor resonant capacitance ratio；

ω_sTo switch angular frequency；

ω_nFor standardization switching frequency；

α is that secondary rectification turns off angle；

I_{r_rms}For the virtual value of resonance current；

V_oFor output voltage.

The realization of switching tube ZVS can ensure that φ characterizes the journey of resonant tank current lagging voltage by increasing φ Degree.After circuit parameter determines, φ can only be increased by improving switching frequency, and switching frequency is lifted and can largely changed The steady-state characteristic of changer, increased parts selection and other each link parameter designing difficulty, also result in more losses.

In practice can be by reducing φ in order to ensure ZVS_AB1Mode realizing.PWM phase shifts mixing proposed by the present invention Control has higher control freedom degree, and phase shifting angle θ and dutycycle d have together decided on φ_AB1Characteristic.

PWM phase shifts mixing controls down the expression formula of standardization resonance current virtual value：

When controlled quentity controlled variable (θ, d) change when, I_nAnd φ_AB1Changing Pattern it is contrary.Change control in order to reduce resonance current Amount can cause φ_AB1Increase, understand that this change reduces can ZVS domains degree by (8) first formulas of formula, destroy LCC resonant transformations The ZVS characteristics of device.Therefore it is conflict body to reduce resonance current and ensure that ZVS is realized, that is, optimize conduction loss and switch is damaged Consumption cannot be realized, one aspect is optimized will necessarily destroy the characteristic of other side.Therefore, it is real In border in design control method the two compromise of reply.

To solve the above problems, the present invention proposes a kind of improved PWM phase shifts mixing control method, is maintaining to specify output Power is constant, ensure ZVS realize on the premise of, by change controlled quentity controlled variable (θ, combination d) reducing resonance current, so as to reach Improve the optimization purpose of transducer effciency.

The principle that improvement PWM phase shifts mix control is further elaborated with reference to Fig. 2.Curve is perunit in figure Change output P_nEqual pitch contour.Assume that LCC controlled resonant converters are in a certain steady statue, corresponding controlled quentity controlled variable (θ_A, d_A) in figure Represented with A points, and with P_nAs a example by=0.6.Optimization process is：Make controlled quentity controlled variable move along current equal pitch contour (by ensure output Power is constant), mobile direction is the direction that reduce can resonance current, as shown by arrows in FIG..On the other hand according to control The change of amount processed carries out real-time judge using formula (8) to ZVS conditions, works as φ_AB1Controlled quentity controlled variable stops moving after reducing to a certain extent It is dynamic, reach B points.Corresponding controlled quentity controlled variable (the θ of the point_B, d_B) it is optimum control point.When load changing, output changes, Controlled quentity controlled variable is moved to an other equal pitch contour under Voltage loop effect from current equal pitch contour.By algorithm controls (θ, it is d) only online (in figure by taking output reduction as an example) is displaced between different Pn equal pitch contours on section OA and its extended line, and O is maximum work output Rate point (θ, d)=(0,0.5).After LCC controlled resonant converters come back to steady statue, the above-mentioned steady-state optimization process of repetition, i.e., Can reach optimum control point C：(θ_C, d_C)。

Fig. 3 show the control system block diagram of the inventive method.First to the output voltage V of changer_oSampled, with The poor e of reference value obtains exporting c as the input of voltage regulator；Sampling is entered to the resonance current of changer, is calculated through optimization Method obtains two coefficient ks₁、k₂；Use k₁、k₂Voltage regulator output order value c is calculated and corrected, PWM phase shifts is obtained and is mixed 2 command values of combination control method：Phase shifting angle θ and dutycycle d；By phase shifting angle and duty instruction value input PWM phase shift mixing Manipulator, obtains the drive signal d of four switching tubes of controlled resonant converter former limit₁、d₂、d₃、d₄.V in figure_inFor input voltage, i_rFor Resonance current, i_RFor rectified output current, i_oFor output current.S1-S4 be primary side switch pipe, L_rFor resonant capacitance, C_sFor series connection Resonant capacitance, C_pFor parallel resonance electric capacity, Tr is transformator, and n is the transformer primary secondary turn ratio, C_fFor output filter capacitor, R_LFor Load.

To realize above-mentioned improved PWM phase shifts mixing control, the present invention proposes a kind of optimized algorithm, by optimized algorithm meter Calculation obtains two coefficient ks₁、k₂, the output order c of Voltage loop is corrected, obtain PWM phase shifts mixing control two controlled quentity controlled variables (θ, d)。

The main task of command value amendment link is to be calculated phase shifting angle instruction according to the output of voltage regulator first Value, plays a part of to carry out quick regulation to output voltage；Next to that calculating duty instruction value, control point is made in stable state or negative Carry mutation process in be at maximum power point (θ, d)=(0,0.5) be located straight line on.It is hereby achieved that command value is repaiied Positive formula：

Wherein k1, k2 are correction factor.

Optimized algorithm flow chart proposed by the present invention is as shown in Figure 4.

First, it is assumed that LCC controlled resonant converters are in a certain steady state point P₀(θ₀, d₀), k₁Initial value is 0, k₂Initial value can lead to Cross and formula (10) is entered into formula (7) be calculated.

Increase k successively₁、k₂, k₁Increase causes phase shifting angle command value to become big, k₂Increase equivalent to increased control point and most The slope of high-power point place straight line, makes calculated duty instruction value become big, the two increase simultaneously make control point towards The direction movement that resonance current reduces.The degree of increase determines the control accuracy of system, can be entered according to real needs in practice Row is arranged.

Then following condition judged successively：

(1) P after controlled quentity controlled variable change is judged according to formula (7)_nFluctuation whether exceed threshold value (1%)；

(2) its virtual value is calculated by resonance current sampled value, and judges whether to reduce；

(3) φ and φ is calculated according to formula (1) and formula (8)_AB1And judge whether to meet ZVS realize condition, be to retain certain ZVS is realized that condition is set as by allowance, the present invention：φ_vi≥10°

3 conditions meet more than simultaneously when, k is updated₁、k₂Value and continue increase, until have in 3 conditions appointing above Meaning one is unsatisfactory for.

Reduce k₂Value and judging whether meet simultaneously more than 3 conditions, if being unsatisfactory for, terminate algorithm and export last time K before updating₁、k₂Value, if meet if update k₁、k₂And export, terminate algorithm, final optimum control is obtained by formula (10) Point.

Knowable in above-mentioned analysis, it is stable that PWM phase shifts mixing control proposed by the present invention is rapidly achieved can system, bag Include the output change procedure that load changing is caused；And command value optimization conditioning ring energy-conservation is maintaining to specify output not On the premise of change, guarantee ZVS are realized, by changing controlled quentity controlled variable, (θ, combination d) minimizes resonance current, so as to reach raising The optimal control target of transducer effciency.

The above is only the preferred embodiment of the present invention, it should be pointed out that：For the ordinary skill people of the art For member, under the premise without departing from the principles of the invention, some improvements and modifications can also be made, these improvements and modifications also should It is considered as protection scope of the present invention.

Claims (5)

1. a kind of LCC controlled resonant converters PWM phase shifts mixing is controlled and efficiency optimization method, it is characterised in that：Perform including order Following steps：

Step one, the output voltage to LCC controlled resonant converters carry out sampling and obtain output voltage sampled value, and output voltage is sampled Value makes the difference with reference value and obtains voltage difference, using the voltage difference for obtaining as the input of voltage regulator, obtains voltage regulator Output order value c；

Step 2, the resonance current to LCC controlled resonant converters are sampled, and through optimized algorithm two correction factor k are obtained₁、 k₂；

Step 3, use correction formulaCalculate and obtain phase shifting angle θ and dutycycle d this 2 command values；

Step 4, by phase shifting angle θ and dutycycle d, this 2 command values are input into PWM phase shift hybrid modulation devices, obtain LCC controlled resonant converters The drive signal of four switching tubes of former limit；

In said process, the calculation process of optimized algorithm is in the step 2：

Step (1), setting k₁Initial value be 0, according to any steady state point P of LCC controlled resonant converters₀(θ₀, d₀) and amendment public affairs Formula obtains k₂Initial value；

Step (2), while increase k₁、k₂Value, judge k₁、k₂Phase shifting angle θ and dutycycle d after increase is to meet update condition；

Step (3), update if update condition is met k₁、k₂Value, and obtain new phase shifting angle θ and dutycycle d, and repeat to walk Suddenly (2), step (4) is proceeded to if update condition is unsatisfactory for；

Step (4), reduction k₂Value, judge k₂Whether the phase shifting angle θ and dutycycle d after reduction meets update condition；

Step (5), terminate if condition is unsatisfactory for algorithm and export last time update before k₁、k₂Value, update if condition is met k₂Value, and export k₁、k₂Value.

2. as claimed in claim 1 a kind of LCC controlled resonant converters PWM phase shifts mixing is controlled and efficiency optimization method, and its feature exists In：The update condition that meets in the step (2), (4) is specially following 3 conditions of satisfaction simultaneously：

After condition (1), control variable θ, d update, the standardization output P of LCC controlled resonant converters_nFluctuation less than setting Threshold value；

Condition (2), the virtual value of the resonance current of LCC controlled resonant converters reduce；

Condition (3), meet Sofe Switch ZVS and realize condition：φ_vi=φ-φ_AB1≥10°；

Wherein：

φ_viFor LCC controlled resonant converter former limit output voltage V_ABWith resonance current i_rBetween phase angle；

φ is LCC controlled resonant converter equivalent circuit input impedances angle；

φ_AB1For LCC controlled resonant converter former limit output voltage V_ABFundametal compoment V_AB1Phase angle.

3. as claimed in claim 1 or 2 a kind of LCC controlled resonant converters PWM phase shifts mixing is controlled and efficiency optimization method, its feature It is：Modulation of the PWM phase shifts hybrid modulation device to LCC controlled resonant converters in the step 4 is carried out according to following 4 conditions：

Switching tube S2 is complementary under switching tube S1 and former limit leading-bridge on condition (1), the former limit leading-bridge of LCC controlled resonant converters Conducting, the complementary conductings of switching tube S4 under switching tube S3 and former limit lagging leg on former limit lagging leg；

The dutycycle of switching tube S1 is constant on condition (2), former limit leading-bridge, is 50%；

Condition (3), triangular carrier amplitude are 1, and frequency is 2 times of switching frequencies；Triangular carrier k-th switch periods from 2 θ [k]/ π is started counting up, and wherein θ [k] is the phase shifting angle of k-th switch periods, and k is arbitrary integer；

Switching tube S4 drive signals are low level k-th starting stage in cycle under condition (4), former limit lagging leg, first High level is turned into when carrier wave is equal to d [k] in individual triangular carrier rising edge, in subsequent triangular carrier trailing edge triangle is worked as Upset when carrier wave is equal to d [k] is low level, and d [k] is duty instruction value.

4. as claimed in claim 2 a kind of LCC controlled resonant converters PWM phase shifts mixing is controlled and efficiency optimization method, and its feature exists In：In the condition (1), the standardization output P of LCC controlled resonant converters_nComputing formula be：

$P_n=\frac{cos\left(2\mathrm{\π}\right(0.5-d\left)\right)+4cos\mathrm{\θ}\·cos\left(\mathrm{\π}\right(0.5-d\left)\right)+3}{8}$

5. a kind of LCC controlled resonant converters PWM phase shifts mixing as claimed in claim 2 is controlled and efficiency optimization method, its feature It is：In the condition (3), LCC controlled resonant converter equivalent input impedances angle φ and V_AB1Angle phi_AB1Computing formula For：

$\left\{\begin{array}{c}\mathrm{\φ}=arctan\left(\frac{\mathrm{\π}A({\mathrm{\ω}}_n^2-1)+sin\mathrm{\α}cos\mathrm{\α}-\mathrm{\α}}{\left({\sin }^2\mathrm{\α}\right)}\right)\\ {\mathrm{\φ}}_{AB1}=arctan\left(\frac{\sin \mathrm{\θ}\cos \left(\mathrm{\π}\right(0.5-d\left)\right)}{\cos \mathrm{\θ}\cos \left(\mathrm{\π}\right(0.5-d\left)\right)+1}\right)\\ \mathrm{\α}=\arccos (1-\frac{\sqrt{2}{\mathrm{\ω}}_s{V}_o{C}_p}{I_{r\_rms}})\end{array}\right.$

Wherein：

A=C_p/C_sFor resonant capacitance ratio；C_s、C_pRespectively series and parallel resonant capacitance；

ω_sTo switch angular frequency；

ω_nFor standardization switching frequency；

α is that secondary rectification turns off angle；

I_{r_rms}For resonance current virtual value；

V_oFor output voltage.