Utility model content
The purpose of this utility model is to provide a kind of total current section BOOST circuit control mode being applicable to photovoltaic MPPT, comprises circuit and control method thereof.The utility model, when the switching tube duty ratio of control BOOST, is achieved by the judgement of DSP and controls respectively the total current section of BOOST circuit, has circuit simple, system stability, the lower-cost advantage of the components and parts used.
Technical solutions of the utility model: the total current section BOOST circuit of a kind of photovoltaic MPPT, by inductance L, HF switch pipe Q, diode D and capacitor C forms basic BOOST circuit, described inductance L, diode D and capacitor C is serially connected in photovoltaic cell the two poles of the earth successively, the drain electrode of described HF switch pipe Q connects the anode of diode D, grid receives the total current section control signal from DSP, capacitor C described in source electrode connects, wherein said DSP is by the input voltage of the basic BOOST circuit of sampling, output voltage and input current carry out computing to determine its operating state, to export total current section control signal.
In one embodiment, described DSP is configured to: if judge, basic BOOST circuit is in DCM state, and computed duty cycle is to carry out opened loop control; If judge, basic BOOST circuit is in CCM state, then carry out closed-loop control.
In one embodiment, described DSP judges the operating state of basic BOOST circuit, controls its HF switch pipe Q and carries out corresponding PWM drive singal to carry out the control of total current section.
In another embodiment, the BOOST circuit total current section control method of a kind of photovoltaic MPPT, in described total current section BOOST circuit, comprising: by the input voltage V of DSP by described basic BOOST circuit
in, output voltage V
owith input current I
insample laggard row operation, judge the operating state of described basic BOOST circuit, be in DCM operating state if be judged as, then computed duty cycle is to carry out opened loop control; Be in CCM operating state if be judged as, then carry out closed-loop control; The HF switch pipe Q controlling described basic BOOST circuit carries out corresponding PWM drive singal to carry out the control of total current section.Wherein:
To the input voltage V of described basic BOOST circuit
inwith output voltage V
osample, according to inductance L inductance value, switching frequency, input voltage V
inwith output voltage V
ocalculate the critical point electric current I of described basic BOOST circuit under DCM and CCM two operating states
c;
To described basic BOOST circuit input current I
incarry out sampling and judging, if I
in>I
c, then judge that this basic BOOST circuit working is in CCM state; Otherwise, if I
in<I
c, then judge that this basic BOOST circuit BOOST is operated in DCM state.
Wherein, judge that basic BOOST circuit working is under CCM state, then provide reference voltage V by MPPT control ring at described DSP
ref; By described reference voltage V
refwith output voltage V
ocarry out outer voltage to control to obtain electric current loop reference current I
ref; By reference current I
refwith output current I
ocarry out current inner loop control; And obtain the PWM drive singal of HF switch pipe Q of described basic BOOST circuit through PI ring, transfer function and PWM control ring, to carry out double-closed-loop control.
Further, judge that basic BOOST circuit working is under DCM state at described DSP, then by DSP to input voltage V
in, output voltage V
o, electric current loop reference current I
ref, switching frequency and inductance L inductance value carry out calculating open loop duty ratio benchmark D
oP; By this open loop duty ratio benchmark D
oPobtain the PWM drive singal of the HF switch pipe Q of described basic BOOST circuit through transfer function and PWM control ring, realize opened loop control.
Compared with prior art, the utility model, when control BOOST switching tube duty ratio, is achieved by the judgement of DSP and controls respectively the total current section of BOOST circuit, has circuit simple, system stability, the lower-cost advantage of the components and parts used.
Embodiment
Below in conjunction with drawings and Examples, the utility model is further described, but not as the foundation limited the utility model.
As shown in Figure 1, basic BOOST circuit is by an inductance L, a HF switch pipe Q, a diode D, and a capacitor C forms.When basic BOOST circuit working, to input voltage V
inwith output voltage V
odSP (not showing in figure) is sent into, by DSP according to inductance L inductance value, switching frequency, input voltage V after sampling
inwith output voltage V
ocalculate the critical point electric current I of basic BOOST circuit under DCM and CCM two operating states
c.Meanwhile, DSP is to input current I
insample, its sampled value is judged.If I
in>I
c, then judge that BOOST is operated in CCM state.Otherwise, I
in<I
c, then judge that basic BOOST circuit working is in DCM state.
As shown in Figure 2, when DSP judges that basic BOOST circuit working is under CCM state, then reference voltage V is provided by MPPT control ring
ref, then by reference voltage V
refwith output voltage V
ocarry out outer voltage to control to obtain electric current loop reference current I
ref, then by reference current I
refwith output current I
ocarry out current inner loop control, obtain the PWM drive singal of the HF switch pipe Q of basic BOOST circuit finally by PI ring, transfer function and PWM control ring, realize double-closed-loop control.
Judge that BOOST circuit working is under DCM state at DSP, then by DSP to input voltage V
in, output voltage V
o, electric current loop reference current I
ref, switching frequency and inductance L inductance value carry out calculating open loop duty ratio benchmark D
oP, by this benchmark D
oPobtain the PWM drive singal of BOOST switching tube through transfer function and PWM control ring, realize opened loop control.