CN103529898A - Maximum power point tracing control method applied to photovoltaic charging system - Google Patents

Abstract

The invention provides a maximum power point tracing control method applied to a photovoltaic charging system, and belongs to the technical field of electrical control. Circuit hardware only collects output current signals; by means of operation and processing capacity of a single chip microcomputer, the pulse width of a direct-current converter is controlled and adjusted, electric energy emitted by a solar energy assembly is used for charging a storage battery through the direct-current converter, and the pulse width of the direct-current converter is adjusted in real time according to changes of sunlight intensity so that output power can be close to the maximum power point of the solar energy assembly. The maximum power point tracing control method has the advantages that after equipment operates, it is determined that the hardware only collects the output current signals, the solar energy maximum power point tracing deviation of software is less than 1%, and the efficiency of the hardware is greater than 93%.

Description

A kind of control method that is applied to the MPPT maximum power point tracking of photovoltaic charging system

Technical field

The present invention is a kind of control method that is applied to the MPPT maximum power point tracking of photovoltaic charging system.Belong to Electrical Control Technology field.

Background technology

MPPT maximum power point tracking is an important gordian technique in solar electrical energy generation, and it refers to, for making full use of sun power, the output voltage of control break solar battery array or the method for electric current, always work on maximum power point array.

Conventional solar maximum power point track algorithm has constant voltage-tracing method at present, hill climbing method, stagnant ring relative method, quadratic interpolattion etc., but carry out MPPT maximum power point tracking computing after the voltage and current value that these algorithms are substantially all collection battery components to be exported, these algorithms all exist the speed of tracking slower, collection signal many (electric current and voltage), while applying in photovoltaic charging system, the phenomenon showing is exactly that high (collection signal is many for system failure rate, complicacy and the failure rate of hardware have been increased), when illumination generation acute variation, system responses is slow, easily there is deadlock etc. in software.

Summary of the invention

The object of the invention, for above-mentioned deficiency, only gathers the current signal of output on hardware, simplified hardware circuit, has reduced failure rate.Design a new control method, utilize the calculation process ability of single-chip microcomputer, the pulsewidth of DC converter is implemented to control and regulate, the electric energy sending with solar components charges a battery through DC converter, and according to the variation of intensity of sunshine, regulate in real time the pulsewidth of DC converter, make output power approach the peak power of solar module.

A control method for the MPPT maximum power point tracking of photovoltaic charging system, contains following steps:

Step 1: each variable of initialization; PWM dutycycle variable P=0; Dutycycle correction variables D=1; The constant offset M=5 that dutycycle is fixing;

Step 2: with current PWM dutyfactor value P output, and save as P_A; Gather primary current, and save as I_A;

Step 3:PWM dutyfactor value P deducts a constant M on P_A basis; Output PWM dutyfactor value P_B now, gathers primary current, saves as I_B;

Step 4:PWM dutyfactor value P adds a constant M on P_A basis; Output PWM dutyfactor value P_C now, gathers primary current, saves as I_C;

The P_A that step 5:PWM dutyfactor value P preserves before changeing back;

Step 6: judge that whether I_B and I_C be all little than I_A; If so, forward step 9 to, if not, perform step 7;

Step 7: if judgement I_B is greater than I_C, then judge the positive and negative of current modified value D, negative if, modified value D reduces 1, and if just, modified value D is made as-1; If I_B is less than I_C, then judge the positive and negative of current modified value, if just, modified value D is increasing by 1, and negative modified value D is made as 1 if;

Step 8:PWM dutyfactor value P and the stack of modified value D value, produce a new P value; Be P=P+D;

Step 9: export new PWM dutyfactor value P; Jump to step 2; Circulation according to this, progressively accelerates to approach maximum power point; Anxious stopping after arriving; Dynamically maintain the voltage that closes on maximum power point.

Technique effect of the present invention:

After equipment operation, determine, on hardware, only gather the current signal of output, the error that software solar maximum power point is followed the tracks of is less than 1%, and hardware efficiency is greater than 93%.

Accompanying drawing explanation

When considered in conjunction with the accompanying drawings, by the detailed description with reference to below, can more completely understand better the present invention and easily learn wherein many advantages of following, but accompanying drawing described herein is used to provide a further understanding of the present invention, form a part of the present invention, schematic description and description of the present invention is used for explaining the present invention, does not form inappropriate limitation of the present invention, wherein:

Fig. 1 is hardware block diagram of the present invention.

Fig. 2 is program flow diagram of the present invention.

Embodiment

Obviously, the many modifications and variations that those skilled in the art do based on aim of the present invention belong to protection scope of the present invention.

Embodiment 1: as shown in the hardware block diagram of Fig. 1, single-chip microcomputer connects current collecting device and solar module, and single-chip microcomputer connects DC-DC DC converter by pulsewidth output instruction signal, and DC-DC DC converter connects solar module and accumulator.

Solar module is to DC-DC DC converter and single-chip microcomputer power supply, current collecting device gathers output current signal and sends into single-chip microcomputer, single-chip microcomputer is according to the variation of output current, after calculation process, output pulse width output order control signal is after DC-DC DC converter, DC-DC DC converter is controlled output current value, completes the control that solar maximum power point is followed the tracks of.

Embodiment 2: as shown in the program flow diagram of Fig. 2, a kind of control method that is applied to the MPPT maximum power point tracking of photovoltaic charging system, contains following steps;

Step 1: each variable of initialization; PWM dutycycle variable P=0; Dutycycle correction variables D=1; The constant offset M=5 that dutycycle is fixing;

Step 2: with current PWM dutyfactor value P output, and save as P_A; Gather primary current, and save as IA;

Step 3:PWM dutyfactor value P deducts a constant M on P_A basis; Output PWM dutyfactor value P_B now, gathers primary current, saves as I_B;

Step 4:PWM dutyfactor value P adds a constant M on P_A basis; Output PWM dutyfactor value P_C now, gathers primary current, saves as I_C;

The P_A that step 5:PWM dutyfactor value P preserves before changeing back;

Step 6: judge that whether I_B and I_C be all little than I_A; If so, forward step 9 to, if not, perform step 7;

Step 7: if judgement I_B is greater than I_C, then judge the positive and negative of current modified value D, negative if, modified value D reduces 1, and if just, modified value D is made as-1; If I_B is less than I_C, then judge the positive and negative of current modified value, if just, modified value D is increasing by 1, and negative modified value D is made as 1 if;

Step 8:PWM dutyfactor value P and the stack of modified value D value, produce a new P value; Be P=P+D;

Step 9: export new PWM dutyfactor value P; Jump to step 2; Circulation according to this, progressively accelerates to approach maximum power point; Anxious stopping after arriving; Dynamically maintain the voltage that closes on maximum power point.

Embodiment 3: as shown in the program flow diagram of Fig. 2, a kind of control method that is applied to the MPPT maximum power point tracking of photovoltaic charging system, contains following steps;

Step 1; Initialization; Arrange:

P=0 PWM Duty ratio control variable;

D=1 PWM dutycycle correction variable;

M=5 PWM dutycycle constant offset constant;

Step 2; Preserve current P value for P_A, gather primary current, save as I_A;

Step 3; Assignment P=P_A-M, gathers primary current, saves as I_B;

Step 4; Assignment P=P_A+M, gathers primary current, saves as I_C;

Step 5; Recover P value, i.e. P=P_A;

Step 6; If I_A >=I_B and I_A >=I_C; If so, turn to step 15; Otherwise turn to step 7;

Step 7; If I_B > is I_C, if so, turn to step 8; Otherwise turn to step 11;

Step 8; If D < 0, if so, turns to step 9; Otherwise turn to step 10;

Step 9; Assignment D=D-1;

Step 10; Assignment D=-1;

Step 11; If D > 0, if so, turns to step 12; Otherwise turn to step 13;

Step 12; Assignment D=D+1;

Step 13; Assignment D=1;

Step 14; PWM initial value and modified value stack, i.e. P=P+D;

Step 15; Export new P value; Jump to step 2; Circulation according to this.

As mentioned above, embodiments of the invention are explained, but as long as not departing from fact inventive point of the present invention and effect can have a lot of distortion, this will be readily apparent to persons skilled in the art.Therefore, within such variation is also all included in protection scope of the present invention.

Claims (2)

1. a control method for the MPPT maximum power point tracking of photovoltaic charging system, is characterized in that: the current signal that only gathers output on circuit hardware; Utilize the calculation process ability of single-chip microcomputer, the pulsewidth of DC converter is implemented to control and regulate, the electric energy sending with solar components charges a battery through DC converter, and according to the variation of intensity of sunshine, regulate in real time the pulsewidth of DC converter, make output power approach the maximum power point operation of solar module.

2. a kind of control method that is applied to the MPPT maximum power point tracking of photovoltaic charging system according to claim 1, is characterized in that containing following steps:

Step 1: each variable of initialization; PWM dutycycle variable P=0; Dutycycle correction variables D=1; The constant offset M=5 that dutycycle is fixing;

Step 2: with current PWM dutyfactor value P output, and save as P_A; Gather primary current, and save as I_A;

Step 3:PWM dutyfactor value P deducts a constant M on P_A basis; Output PWM dutyfactor value P_B now, gathers primary current, saves as I_B;

Step 4:PWM dutyfactor value P adds a constant M on P_A basis; Output PWM dutyfactor value P_C now, gathers primary current, saves as I_C;

The P_A that step 5:PWM dutyfactor value P preserves before changeing back;

Step 6: judge that whether I_B and I_C be all little than I_A; If so, forward step 9 to, if not, perform step 7;

Step 7: if judgement I_B is greater than I_C, then judge the positive and negative of current modified value D, negative if, modified value D reduces 1, and if just, modified value D is made as-1; If I_B is less than I_C, then judge the positive and negative of current modified value, if just, modified value D is increasing by 1, and negative modified value D is made as 1 if;

Step 8:PWM dutyfactor value P and the stack of modified value D value, produce a new P value; Be P=P+D;

Step 9: export new PWM dutyfactor value P; Jump to step 2; Circulation according to this, progressively accelerates to approach maximum power point; Anxious stopping after arriving; Dynamically maintain the voltage that closes on maximum power point.

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