CN106487215A - CRM boost PFC changer changes the optimal control of ON time - Google Patents

Abstract

The invention discloses CRM boost PFC changer changes the optimal control of ON time, may be implemented in the unification changing ON time under wide input voltage and variable load occasion, it is to avoid to v in traditional method_inMore than or less than V_o/ 2 two kinds of different situations carry out the complexity problem controlling of classifying.The present invention is inputted by sampling and output voltage instantaneous value, calculates or signal condition through real-time accordingly, the ON time of real-time adjustment switching tube is to reduce input current abnormality.The constant component of ON time is adjusted by voltage PI ring, and variable part is calculated according to unified algorithm by digitial controller or by the peripheral circuit real-time regulation such as analog divider.The present invention need not detect output and input voltage virtual value, and without input voltage phase lock circuitry, by normalized control method realize changer in working range arbitrarily under the conditions of change ON time control, thus significantly simplifying circuit cost and controlling difficulty.

Description

CRM boost PFC changer changes the optimal control of ON time

Technical field

The present invention relates to power inverter technology is and in particular to one kind is applied to the change conducting of CRM boost PFC changer The optimal control of time.

Background technology

The extensive application of power electronic equipment, brings substantial amounts of harmonic pollution to electrical network, has had a strong impact on the confession of electrical network Electricity quality and the normal work of other electrical equipments.In order to reduce the harmonic pollution that power electronic equipment brings, meet international electricity The harmonic standard IEC61000-3-2 that work committee formulates, needs using PFC (Power Factor Correction, PFC) changer suppresses harmonic component to make all kinds of electrical equipments reach required harmonic standard.Wherein, CRM Boost PFC changer due to its power factor height, small volume, lightweight and low cost and other advantages and be widely used.

The change ON time of CRM boost PFC changer controls and typically passes through to increase positive inductive current ON time The loss that the compensation reverse resonance of inductive current is brought is so that the meansigma methodss of inductive current are equal with sinusoidal benchmark current value.But It is to need to v when model analyses_inMore than or less than V_o/ 2 two kinds of different situations are discussed respectively, the control of digital method Algorithm is complicated, and when being realized using analog hardware, needs to realize different turn-on control circuits in the case of two kinds, under different condition The function such as judgement of relation between the switching of ON time control circuit and input voltage and output voltage.This kind of control method The cost of control circuit and power consumption are significantly increased it is difficult to meet sending out of the high-efficiency and low-cost of CRM boost PFC changer Exhibition demand.It is thus desirable to traditional change ON time is controlled being optimized.

Content of the invention

The invention aims to solving during traditional CRM boost PFC changer change ON time controls for v_inGreatly In or be less than V_o/ 2 both of these cases need to calculate brought complex calculation problem respectively, and proposing one kind can be by analog control circuit Or the optimal control method that digitial controller is realized, the method do not need to carry out the survey of power detection and input voltage virtual value Amount, under the conditions of any in CRM boost PFC changer working range, switching tube ON time T_onT the calculating process of () is all It is consistent, thus reducing computational complexity and system cost.

Above-mentioned purpose is achieved by the following technical solution：

A kind of CRM boost PFC changer changes ON time optimal control, and it is realized circuit and includes CRM boost PFC Inverter main circuit and control circuit.Control circuit is by input voltage sample circuit, output voltage sampling circuit, inductive current mistake Null detector, digitial controller or analog control circuit are constituted, its digitial controller include ADC analog/digital conversion unit, in Disconnected system, operation processing unit, eCAP enhancement mode pulse capture module and ePWM enhancement mode pulse width modulation module；Its simulation controls Circuit includes pi regulator, divider circuit and differential amplifier circuit.

Wherein, described CRM boost PFC inverter main circuit by electromagnetic interface filter, rectifier bridge, input capacitance, inductance, open Guan Guan, diode, output capacitance and load are constituted；The input of described input voltage sample circuit connects input on rear side of rectifier bridge Electric capacity C_inTwo ends, its outfan connect divider circuit in the input of multiplier or digitial controller ADC thief hatch；Institute The input stating output voltage sampling circuit connects output loading R_loadTwo ends, its outfan by resistance be respectively connecting to transport Put OP₁With amplifier OP₂Reverse input end or digitial controller ADC thief hatch；Amplifier OP of described pi regulator₁Reversely defeated Enter end and connect divider resistance R₃With R₄Between sampled output, positive input connect reference voltage V_ref, output signal V_error Connect to amplifier OP₃Positive input；The input of the multiplier of described divider circuit connects divider resistance R respectively₁With R₂ Between sampled output, and amplifier OP₂Outfan, its outfan pass through resistance R₈Connect amplifier OP₂Reverse input end, Amplifier OP₂Reverse input end by resistance connect divider resistance R₃With R₄Between sampled output, positive input connect work( Rate ground, output signal V_addBy resistance R₉Connect amplifier OP₃Inverting input；Amplifier OP of described differential amplifier circuit₃'s Output signal V_compareConnect to amplifier OP₄Reverse input end.

A kind of CRM boost PFC changer changes the optimal control of ON time, any in changer working range Under the conditions of, the ON time T of switching tube_onT the calculating process of () is all consistent, including step as described below：

1) to ON time T_onThe constant component T of (t)_{on_error}Calculated, this part is adjusted by voltage PI ring, For controlling output and the output voltage of changer；

2) to ON time T_onThe variable part T of (t)_{on_vary}T () is calculated, this part is used for inputting electricity in changer Pressing through zero nearby additionally increases the ON time of switching tube to improve input current abnormality, and its quantitative relationship is as follows：

Wherein, Z_rIt is characteristic impedance,L is the liter in CRM boost PFC inverter main circuit Piezoelectricity inductance value, C_ossIt is the output junction capacitance of switching tube, C_dpIt is the parasitic capacitance value of diode, V_oIt is output voltage instantaneous value, v_inIt is input voltage instantaneous value, input voltage v_inMore than or less than output voltage V_o/2；

3) by error ON time T_{on_error}With real-time variable ON time T_{on_vary}T () is added, obtain work at present bar Corresponding ON time T under part_onT (), is shown below：

T_on(t)=T_{on_error}+T_{on_vary}(t) (2)

4) by corresponding ON time T_onT () is converted to drive signal, realize the change to CRM boost PFC changer ON time controls.

A kind of method realizing above-mentioned optimal control using digitial controller, including step as described below：

1) input capacitance C on rear side of the analog/digital conversion unit sampling changer rectifier bridge of digitial controller_inTwo ends Input voltage v_inWith output loading R_loadThe output voltage V at two ends_o, obtain corresponding sample magnitude v_in/K_inWith V_o/K_o, K_inIt is The partial pressure coefficient of input voltage sample circuit, K_oIt is the partial pressure coefficient of output voltage sampling circuit；

2) output voltage sampled value V_o/K_oWith reference voltage V_refInterruption system is compared, its error amount △ V passes through Error ON time T is generated after voltage PI ring computing_{on_error}.Wherein, reference voltage V_refControl targe value for output voltage is removed With output voltage partial pressure coefficient, typically take 1～3V；

3) operation processing unit of digitial controller according to equation below to T_{on_vary}T () is calculated in real time：

Wherein, Z_rIt is characteristic impedance：L is the liter in CRM boost PFC inverter main circuit Piezoelectricity inductance value, C_ossIt is the output junction capacitance of switching tube, C_dpIt is the parasitic capacitance value of diode；

4) by error ON time T_{on_error}With real-time variable ON time T_{on_vary}T () is added, obtain work at present bar Corresponding ON time T under part_onT (), is shown below：

T_on(t)=T_{on_error}+T_{on_vary}(t) (4)

5) digitial controller eCAP module captures the rising edge signal of the square-wave signal of inductive current zero-crossing detector output, Determine the switching tube in CRM boost PFC inverter main circuit opens the moment；

6) digitial controller ePWM module is by corresponding ON time T_onT () is converted to PWM ripple signal output to driving electricity Road, produces change ON time and controls required drive signal.

A kind of method realizing above-mentioned optimal control using analog control circuit, including step as described below：

1) input and output voltage sample circuit is by sampled value V_o/K_oAnd v_in/K_inDeliver to pi regulator and divider electricity respectively Lu Zhong, K_inIt is the partial pressure coefficient of input voltage sample circuit, K_oIt is the partial pressure coefficient of output voltage sampling circuit；

2) pi regulator circuit is by output voltage sampled value V_o/K_oWith reference voltage value V_refCompare and obtain voltage error Value, and by simulating the corresponding error ON time T of PI computing output_{on_error}Voltage signal V_error, the following institute of corresponding relation Show：

Wherein, by adjusting resistance R₅、R₆With electric capacity C₁Proportionality coefficient and the integral coefficient of pi regulator can be changed；

3) divider circuit calculates variable ON time in real time, and exports corresponding real-time variable ON time T_{on_vary}(t) Voltage signal V_add, the expression formula of this voltage signal is as follows：

Resistance in circuit determines according to following equation：

Then voltage signal V_addCorresponding real-time variable ON time T_{on_vary}T the corresponding relation of () is as follows：

Wherein, K_MIt is the gain coefficient of multiplier, du_saw/ dt is the slope of sawtooth voltage signal, Z_rIt is characteristic impedance：L is the boost inductance value in CRM boost PFC inverter main circuit, C_ossIt is the output of switching tube Junction capacitance, C_dpIt is the parasitic capacitance value of diode；

4) pass through differential amplifier circuit, by voltage signal V_errorAnd V_addBe converted to the comparison voltage needed for modulation wave signal Value V_compare, that is, have：

This comparing voltage value V_compareWith ON time T_onT the corresponding relation of () is as follows：

5) rest-set flip-flop detects that the rising edge signal of the square-wave signal of inductive current zero cross detection circuit output confirms switch Pipe turn-on instant.Comparing voltage value V of modulation wave signal comparator positive and negative terminal_compareA section determination is handed over to open with sawtooth voltage signal Close pipe and turn off the moment.After switching tube is opened, sawtooth signal start from scratch linearly increasing until and V_compareDefeated when equal Go out switching tube cut-off signals, the change ON time completing CRM boost PFC changer controls.

Advantages of the present invention：

1st, the CRM boost PFC changer of the present invention becomes the optimal control of ON time, it is to avoid in traditional control method Need to carry out the complexity problem of Discrete control below or above 1/2 output voltage according to input voltage, proposed unified realization Mode can be below or above the unification under 1/2 output voltage different condition based on a set of hardware simulation circuit realiration input voltage Control, thus simplifying circuit.

2nd, in the ON time computing of the present invention, constant component carries out closed loop regulation by voltage PI ring, therefore can reduce output Power detection link；Variable part is adjusted based on input and output voltage instantaneous sampling value, therefore can save the tradition side of tabling look-up Input voltage phase lock circuitry in formula and the measurement of input voltage virtual value.Answering of peripheral analog circuit therefore can be reduced further Miscellaneous degree and the operand of digital control algorithm, contribute to reducing power consumption and the cost of control system；

3rd, the present invention, by being optimized control to the change ON time of CRM boost PFC changer, can effectively suppress defeated Enter the harmonic content size of electric current, notable to the reducing effect of input current THD.

Brief description

Fig. 1 is the main circuit of CRM boost PFC changer；

Fig. 2 is for realizing the change approximate processing schematic diagram to boost inductor current waveform for the ON time optimal control；

Fig. 3 is the digital control circuit realizing the change ON time optimal control of CRM boost PFC changer of the present invention Figure；

Fig. 4 is the control flow chart based on digitial controller of the present invention；

Fig. 5 is that the employing analog circuit of the present invention is realized changing ON time optimal control to CRM boost PFC changer Schematic diagram；

Fig. 6 is the change ON time that CRM boost PFC changer is respectively adopted constant on-time control and the present invention Control the comparison diagram that the input current THD in the case of 110V and 220V AC-input voltage changes with output；

The primary symbols title of above-mentioned in figure：I_inMains input current；I_LInductive current；I_peakInductive current peak Value；I_valleyInductive current valley；I_avgInductive current meansigma methodss；v_inThe instantaneous voltage at input capacitance two ends；V_o— Output voltage；V_dsThe drain-source step voltage of switching tube；Δ V voltage PI ring error amount；V_compareComparing voltage value；V_ref— Reference voltage；L boost inductance；D diode；C_inInput capacitance；C_ossThe output junction capacity of switching tube；C_qpTwo poles The parasitic capacitance of pipe；C_busOutput capacitance；C₁The coefficient electric capacity of pi regulator；R_loadLoad resistance；R₁Bleeder circuit Resistance；R₂Voltage divider circuit Resistance；R₃Voltage divider circuit Resistance；R₄Voltage divider circuit Resistance；R₅The coefficient electricity of pi regulator Resistance；R₆The coefficient resistance of pi regulator；R₇The coefficient resistance of divider circuit；R₈The coefficient resistance of divider circuit； R₉The coefficient resistance of differential amplifier circuit；R₁₀The coefficient resistance of differential amplifier circuit；K_inInput voltage sample circuit divides Pressure coefficient；K_oOutput voltage sampling circuit partial pressure coefficient；K_MThe multiplication coefficient of multiplier；T_{on_error}During error conducting Between；T_{on_vary}Variable ON time；T_onSwitching tube ON time；du_saw/ dt sawtooth waveforms the rate of rise.

Specific embodiment

Specifically introduce optimal control method and the principle of the present invention with reference to the accompanying drawings and examples.

Embodiment one：

CRM boost PFC changer of the present invention changes the optimal control of ON time, in CRM boost PFC changer work Under the conditions of any in the range of work, the ON time T of switching tube_onT the calculating process of () is all consistent.Controlled by this optimization System, can reduce the complexity of whole control system on the basis of reducing CRM boost PFC changer input current THD, from And reduce system cost.The optimal control being adopted is the average current and sine based on inductance in CRM boost PFC changer The equal principle of reference current, and due to inductive current in switch periods except extremely short resonance time is all linear change Change, inductive current waveform approximate processing can be therefore triangle (see Fig. 2) to simplify the calculating of inductance average current.

The CRM boost PFC changer of the present invention changes the optimal control of ON time, in changer working range Under the conditions of arbitrarily, the ON time T of switching tube_onT the calculating process of () is all consistent, including step as described below：

1) to ON time T_onThe constant component T of (t)_{on_error}Calculated, this part is adjusted by voltage PI ring, For controlling output and the output voltage of changer；

2) to ON time T_onThe variable part T of (t)_{on_vary}T () is calculated, this part is used for inputting electricity in changer Pressing through zero nearby additionally increases the ON time of switching tube to improve input current abnormality, and its quantitative relationship is as follows：

Wherein, Z_rIt is characteristic impedance,L is the liter in CRM boost PFC inverter main circuit Piezoelectricity inductance value, C_ossIt is the output junction capacitance of switching tube, C_dpIt is the parasitic capacitance value of diode, v_inIt is that input voltage is instantaneous Value, V_oIt is output voltage instantaneous value, input voltage v_inMore than or less than output voltage V_o/2；

3) by error ON time T_{on_error}With real-time variable ON time T_{on_vary}T () is added, obtain work at present bar Corresponding ON time T under part_onT (), is shown below：

T_on(t)=T_{on_error}+T_{on_vary}(t) (2)

4) by corresponding ON time T_onT () is converted to drive signal, realize the change to CRM boost PFC changer ON time controls.

The design further of the present invention is unified switching tube ON time T_onCalculation expression, this expression formula passes through Following steps obtain：

1) calculate the sinusoidal reference current I under current operating conditions_ref(t)：

Wherein, f_lIt is line frequency；

2) ignore the non-linear section that extremely short resonant process in switch periods brings, inductive current waveform approximately can be located Reason triangularity, the therefore peak I of inductive current_peakWith valley I_valleyCan be counted by expression formula (4) and expression formula (5) respectively Calculate and obtain：

Meansigma methodss I of inductive current therefore can be calculated by following expression_avg：

3) the average current I according to inductance in CRM boost PFC changer_avgWith sinusoidal reference current I_refEqual is former Reason, can obtain unified ON time T after optimization processing_on(t)；

Wherein, error ON time T_{on_error}The unified ON time T of corresponding optimization_onConstant component in (t), in real time Variable ON time T_{on_vary}T () is corresponding to optimize unified ON time T_onT the variable part in (), that is, have：

Therefore for the ON time T under the conditions of any in CRM boost PFC changer working range, after optimization_on T the expression formula of () is all unified.

This CRM boost PFC changer changes the optimal control of ON time, such as can be passed through following using digitial controller Step is implemented：

1) input capacitance C on rear side of the analog/digital conversion unit sampling changer rectifier bridge of digitial controller_inTwo ends Input voltage v_inWith output loading R_loadThe output voltage V at two ends_o, obtain corresponding sample magnitude v_in/K_inWith V_o/K_o, K_inIt is The partial pressure coefficient of input voltage sample circuit, K_oIt is the partial pressure coefficient of output voltage sampling circuit；

2) output voltage sampled value V_o/K_oWith reference voltage V_refInterruption system is compared, its error amount △ V passes through Error ON time T is generated after voltage PI ring computing_{on_error}.Wherein, reference voltage V_refControl targe value for output voltage is removed With output voltage partial pressure coefficient, typically take 1～3V；

3) operation processing unit of digitial controller according to equation below to T_{on_vary}T () is calculated in real time：

Wherein, Z_rIt is characteristic impedance：L is the liter in CRM boost PFC inverter main circuit Piezoelectricity inductance value, C_ossIt is the output junction capacitance of switching tube, C_dpIt is the parasitic capacitance value of diode；

4) by error ON time T_{on_error}With real-time variable ON time T_{on_vary}T () is added, obtain work at present bar Corresponding ON time T under part_onT (), is shown below：

T_on(t)=T_{on_error}+T_{on_vary}(t) (10)

5) digitial controller eCAP module captures the rising edge signal of the square-wave signal of inductive current zero-crossing detector output, Determine the switching tube in CRM boost PFC inverter main circuit opens the moment；

6) digitial controller ePWM module is by corresponding ON time T_onT () is converted to PWM ripple signal output to driving electricity Road, produces change ON time and controls required drive signal.

This CRM boost PFC changer changes the optimal control of ON time, such as adopt analog control circuit can by with Under type is carried out：

1) input and output voltage sample circuit is by sampled value V_o/K_oAnd v_in/K_inDeliver to pi regulator and divider electricity respectively Lu Zhong, K_inIt is the partial pressure coefficient of input voltage sample circuit, K_oIt is the partial pressure coefficient of output voltage sampling circuit；

2) pi regulator circuit is by output voltage sampled value V_o/K_oWith reference voltage value V_refCompare and obtain voltage error Value, and by simulating the corresponding error ON time T of PI computing output_{on_error}Voltage signal V_error, the following institute of corresponding relation Show：

Wherein, by adjusting resistance R₅、R₆With electric capacity C₁Proportionality coefficient and the integral coefficient of pi regulator can be changed；

3) divider circuit calculates variable ON time in real time, and exports corresponding real-time variable ON time T_{on_vary}(t) Voltage signal V_add, the expression formula of this voltage signal is as follows：

Resistance in circuit determines according to following equation：

Then voltage signal V_addCorresponding real-time variable ON time T_{on_vary}T the corresponding relation of () is as follows：

Wherein, K_MIt is the gain coefficient of multiplier, du_saw/ dt is the slope of sawtooth voltage signal, Z_rIt is characteristic impedance：L is the boost inductance value in CRM boost PFC inverter main circuit, C_ossIt is the output of switching tube Junction capacitance, C_dpIt is the parasitic capacitance value of diode；

4) pass through differential amplifier circuit, by voltage signal V_errorAnd V_addBe converted to the comparison voltage needed for modulation wave signal Value V_compare, that is, have：

This comparing voltage value V_compareWith ON time T_onT the corresponding relation of () is as follows：

5) rest-set flip-flop detects that the rising edge signal of the square-wave signal of inductive current zero cross detection circuit output confirms switch Pipe turn-on instant.Comparing voltage value V of modulation wave signal comparator positive and negative terminal_compareA section determination is handed over to open with sawtooth voltage signal Close pipe and turn off the moment.After switching tube is opened, sawtooth signal start from scratch linearly increasing until and V_compareDefeated when equal Go out switching tube cut-off signals, the change ON time completing CRM boost PFC changer controls.

Change ON time for CRM boost PFC changer controls, the ON time T that the present invention adopts_on(t) Calculating process is unified, it is to avoid need in traditional control method to be below or above 1/2 output voltage according to input voltage Carry out Discrete control and be achieved using different hardware simulation circuit, system cost degree can be significantly reduced and control hardly possible Degree, meet while ensureing relatively low input current THD CRM boost PFC changer simple to control circuit, reliable and low become This growth requirement.

Embodiment two：CRM Boost pfc converter is realized based on TMS320F28335 digitial controller and becomes ON time The ON time computing controlling optimizes unified digital control method

Fig. 1 is the main circuit of CRM boost PFC changer, including electromagnetic interface filter, rectifier bridge, input capacitance, rises piezoelectricity Sense, switching tube, diode, output capacitance and load.The circuit parameter of CRM boost PFC changer used in example is： Boost inductance value L=230uH, parasitic capacitance capacitance C of power device_oss+C_dp=80pF.Test condition is：Line frequency 50Hz, AC-input voltage 110V and 220V, export busbar voltage 400V, fully loaded output 200W.This example exists respectively 20%th, in the case of 40%, 50%, 60%, 80% and 100% load, contrast constant on-time controls to input current THD Tested.

Fig. 3 is to realize optimizing the digital control circuit figure being uniformly controlled, except main circuit increased voltage sampling circuit, inductance Current over-zero testing circuit, drive circuit and modulation wave signal produce circuit.

The control process based on TMS320F28335 digitial controller for the present invention is as shown in the control flow chart of Fig. 4：

1) ADC of digitial controller, ePWM module, eCAP module and voltage PI ring are initialized, and take input electricity Pressure downsampling factor K_inFor 125, output voltage downsampling factor K_oFor 160, reference voltage V_refControl targe value for output voltage is removed With output voltage downsampling factor, i.e. V_refFor 2.5V, constant boost inductance value L is 230 μ H, characteristic impedance

2) digitial controller response ADC interrupt routine, to output voltage V_oWith input voltage v_inSampled, obtained partial pressure Actual sample value V afterwards_o/K_oAnd v_in/K_in；

3) call Voltage loop proportional, integral compensation program calculation error ON time T_{on_error}：

T_{on_error}=T'_{on_error}+K_p×(ΔV-ΔV')+K_i×ΔV (17)

Wherein, K_pIt is the proportionality coefficient of voltage PI ring, K_iIt is the integral coefficient of voltage PI ring, Δ V is this cycle output voltage Sampled value V_o/K_oWith reference voltage V_refError amount, Δ V' is upper a cycle output voltage sampled value V_o/K_oWith reference voltage V_refError amount, T_{on_error}It is the result of calculation of this periodic voltage PI ring, T '_{on_error}It is the calculating of last periodic voltage PI ring Result；

4) calculate variable ON time T in real time_{on_vary}(t)：

5) by error ON time T_{on_error}With real-time variable ON time T_{on_vary}T () is added, obtain work at present bar Corresponding ON time T under part_on(t)：

T_on(t)=T_{on_error}+T_{on_vary}(t) (19)

6) digitial controller eCAP module captures the rising edge letter of the square-wave signal of inductive current zero cross detection circuit output Number, determine the switching tube in CRM boost PFC inverter main circuit opens the moment；

7) digitial controller ePWM module is by corresponding ON time T_onT () is converted to PWM ripple signal output to driving electricity Road, produces change ON time and controls required drive signal；

8) repeat step 2)～7).

Fig. 6 is the change ON time that CRM boost PFC changer is respectively adopted constant on-time control and the present invention Control the comparison diagram that the input current THD in the case of 110V and 220V AC-input voltage changes with output.

Can be seen that the optimal control of change ON time proposed by the invention from comparison diagram, in 20% load When, the THD of CRM boost PFC changer input current can be down to 2.64% from 18.38%, significantly improves input electricity The situation of stream distortion.

This simulation result shows：The optimal control that CRM boost PFC changer proposed by the invention becomes ON time exists Avoiding in traditional control method while significantly reducing input current THD needs to v_inMore than or less than V_oDo not sympathize with for/2 two kinds Condition carries out the complexity problem controlling of classifying, thus it is simple to control circuit, reliable and low to meet CRM boost PFC changer The growth requirement of cost.

Embodiment three：When the conducting that ON time controls is become by analog circuit control realization CRM boost PFC changer Between computing optimization unification

Fig. 1 is the main circuit of CRM boost PFC changer, including electromagnetic interface filter, rectifier bridge, input capacitance, rises piezoelectricity Sense, switching tube, diode, output capacitance and load.The circuit parameter of CRM boost PFC changer used in example is： Boost inductance value L=230 μ H, parasitic capacitance capacitance C of power device_oss+C_dp=80pF, the gain coefficient K of multiplier_MFor 0.1/V.Test condition is：Line frequency 50Hz, AC-input voltage 110V and 220V, export busbar voltage 400V, be fully loaded with defeated Go out power 200W.

Fig. 5 realizes CRM boost PFC changer using analog control method and becomes the ON time computing that ON time controls The unified schematic diagram of optimization, include voltage sampling circuit, inductive current zero cross detection circuit, drive circuit, pi regulator electric Road, divider circuit and differential amplifier circuit.

Present invention simulation control process is as follows：

1) input and output voltage sample circuit is by sampled value V_o/K_oAnd v_in/K_inDeliver to pi regulator and divider electricity respectively Lu Zhong, wherein, the partial pressure COEFFICIENT K of input voltage sample circuit_inFor 30, the partial pressure COEFFICIENT K of output voltage sampling circuit_oFor 200, Reference voltage value V_ref=400/200=2V；

2) pi regulator circuit is by output voltage sampled value V_o/K_oWith reference voltage value V_refCompare and obtain voltage error Value, and by simulating the corresponding error ON time T of PI computing output_{on_error}Voltage signal V_error.Wherein, by adjustment electricity Resistance R₅、R₆With electric capacity C₁Proportionality coefficient and the integral coefficient of pi regulator can be changed；

3) divider circuit calculates variable ON time in real time, and exports corresponding real-time variable ON time T_{on_vary}(t) Voltage signal V_add, this voltage signal meets following expression：

Wherein, the gain coefficient K of multiplier_MFor 0.1/V；

4) pass through differential amplifier circuit, by voltage signal V_errorAnd V_addBe converted to the comparison voltage needed for modulation wave signal Value V_compare, that is, have：

This comparing voltage value V_compareCorresponding ON time T_onExpression formula as follows：

Wherein, the slope du of sawtooth voltage signal_saw/ dt is 1V/ μ s, desirable R₉=10k Ω, R₁₀=1k Ω it is possible to Determine the resistance R in divider circuit by following equation₇And R₈：

Then can use resistance R₇=11k Ω, R₈=10k Ω；

5) rest-set flip-flop detects that the rising edge signal of the square-wave signal of inductive current zero cross detection circuit output confirms switch Pipe turn-on instant.Comparing voltage value V of modulation wave signal comparator positive and negative terminal_compareA section determination is handed over to open with sawtooth voltage signal Close pipe and turn off the moment.After switching tube is opened, sawtooth signal start from scratch linearly increasing until and V_compareDefeated when equal Go out switching tube cut-off signals, complete the optimization system that CRM boost PFC changer becomes the ON time computing that ON time controls One.

The inventive method does not need to carry out the measurement of power detection and input voltage virtual value, in the conversion of CRM boost PFC Under the conditions of any in device working range, switching tube ON time T_onT the calculating process of () is all consistent, thus reducing fortune Calculate complexity and system cost.

Claims (5)

1. what a kind of CRM boost PFC changer changed ON time optimal control realizes circuit, includes the change of CRM boost PFC Parallel operation main circuit and control circuit it is characterised in that：Described control circuit is sampled electric by input voltage sample circuit, output voltage Road, inductive current zero-crossing detector, digitial controller or analog control circuit are constituted；Described analog control circuit includes PI and adjusts Device, divider circuit and differential amplifier circuit.

2. what CRM boost PFC changer as claimed in claim 1 changed ON time optimal control realizes circuit, and it is special Levy and be：Described CRM boost PFC inverter main circuit by electromagnetic interface filter, rectifier bridge, input capacitance, inductance, switching tube, two Pole pipe, output capacitance and load are constituted；The input of described input voltage sample circuit connects input capacitance C on rear side of rectifier bridge_in Two ends, its outfan connect divider circuit in the input of multiplier or digitial controller ADC thief hatch；Described output The input of voltage sampling circuit connects output loading R_loadTwo ends, its outfan is respectively connecting to amplifier OP by resistance₁With Amplifier OP₂Reverse input end or digitial controller ADC thief hatch；Amplifier OP of described pi regulator₁Reverse input end connect Divider resistance R₃With R₄Between sampled output, positive input connect reference voltage V_ref, output signal V_errorConnect to fortune Put OP₃Positive input；The input of the multiplier of described divider circuit connects divider resistance R respectively₁With R₂Between adopt Sample outfan, and amplifier OP₂Outfan, its outfan pass through resistance R₈Connect amplifier OP₂Reverse input end, amplifier OP₂'s Reverse input end connects divider resistance R by resistance₃With R₄Between sampled output, positive input connect Power Groud, output Signal V_addBy resistance R₉Connect amplifier OP₃Inverting input；Amplifier OP of described differential amplifier circuit₃Output signal V_compareConnect to amplifier OP₄Reverse input end.

3. described in claim 1 or 2 CRM boost PFC changer change ON time optimal control method it is characterised in that： Under the conditions of any in CRM boost PFC changer working range, ON time T_onT () calculating process step is as follows：

1) to ON time T_onThe constant component T of (t)_{on_error}Calculated, this part is adjusted by voltage PI ring, for controlling The output of changer processed and output voltage；

2) to ON time T_onThe variable part T of (t)_{on_vary}T () is calculated, this part is used in changer input voltage mistake Zero nearby additionally increases the ON time of switching tube to improve input current abnormality, and its quantitative relationship is as follows：

$T_{on\_\mathrm{var}y}\left(t\right)=\frac{L}{Z_r}\×\frac{V_o}{v_{in}}---\left(1\right)$

Wherein, Z_rIt is characteristic impedance,L is the liter piezoelectricity in CRM boost PFC inverter main circuit Inductance value, C_ossIt is the output junction capacitance of switching tube, C_dpIt is the parasitic capacitance value of diode, v_inIt is input voltage instantaneous value, V_oIt is Output voltage instantaneous value, input voltage v_inMore than or less than output voltage V_o/2；

3) by error ON time T_{on_error}With real-time variable ON time T_{on_vary}T () is added, obtain under current operating conditions Corresponding ON time T_onT (), is shown below：

T_on(t)=T_{on_error}+T_{on_vary}(t) (2)

4) by corresponding ON time T_onT () is converted to drive signal, realize the change conducting to CRM boost PFC changer Time control.

4. optimal control method as claimed in claim 3, realizes it is characterised in that comprising the steps through digitial controller：

1) input capacitance C on rear side of the analog/digital conversion unit sampling changer rectifier bridge of digitial controller_inThe input at two ends Voltage v_inWith output loading R_loadThe output voltage V at two ends_o, obtain corresponding sample magnitude v_in/K_inWith V_o/K_o, K_inIt is input The partial pressure coefficient of voltage sampling circuit, K_oIt is the partial pressure coefficient of output voltage sampling circuit；

2) output voltage sampled value V_o/K_oWith reference voltage V_refInterruption system is compared, its error amount △ V is through overvoltage Error ON time T is generated after PI ring computing_{on_error}.Wherein, reference voltage V_refFor output voltage control targe value divided by defeated Go out voltage division factor, typically take 1～3V；

3) operation processing unit of digitial controller according to equation below to T_{on_vary}T () is calculated in real time：

$T_{on\_\mathrm{var}y}\left(t\right)=\frac{L}{Z_r}\×\frac{V_o}{v_{in}}---\left(3\right)$

Wherein, Z_rIt is characteristic impedance：L is the liter piezoelectricity in CRM boost PFC inverter main circuit Inductance value, C_ossIt is the output junction capacitance of switching tube, C_dpIt is the parasitic capacitance value of diode；

4) by error ON time T_{on_error}With real-time variable ON time T_{on_vary}T () is added, obtain under current operating conditions Corresponding ON time T_onT (), is shown below：

T_on(t)=T_{on_error}+T_{on_vary}(t) (4)

5) digitial controller eCAP module captures the rising edge signal of the square-wave signal of inductive current zero-crossing detector output, determines Switching tube in CRM boost PFC inverter main circuit open the moment；

6) digitial controller ePWM module is by corresponding ON time T_onT () is converted to PWM ripple signal output to drive circuit, produce Changing ON time controls required drive signal.

5. optimal control method as claimed in claim 3, realizes through analog control circuit it is characterised in that including following walking Suddenly：

1) input and output voltage sample circuit is by sampled value V_o/K_oAnd v_in/K_inDeliver to respectively in pi regulator and divider circuit, K_inIt is the partial pressure coefficient of input voltage sample circuit, K_oIt is the partial pressure coefficient of output voltage sampling circuit；

2) pi regulator circuit is by output voltage sampled value V_o/K_oWith reference voltage value V_refCompare and obtain voltage error value, and By simulating the corresponding error ON time T of PI computing output_{on_error}Voltage signal V_error, corresponding relation is as follows：

$T_{on\_error}=\frac{(1+R_{10}/R_9)\×V_{compare}}{{\mathrm{du}}_{saw}/dt}---\left(5\right)$

Wherein, by adjusting resistance R₅、R₆With electric capacity C₁Proportionality coefficient and the integral coefficient of pi regulator can be changed；

3) divider circuit calculates variable ON time in real time, and exports corresponding real-time variable ON time T_{on_vary}The voltage of (t) Signal V_add, the expression formula of this voltage signal is as follows：

$V_{add}=-\frac{R_8}{K_M{R}_7}\×\frac{V_o/K_o}{v_{in}/K_{in}}---\left(6\right)$

Resistance in circuit determines according to following equation：

$\frac{R_{10}}{R_9}\×\frac{K_{in}{R}_8}{K_M{K}_o{R}_7}\×\frac{1}{{\mathrm{du}}_{saw}/dt}=\frac{L}{Z_r}---\left(7\right)$

Then voltage signal V_addCorresponding real-time variable ON time T_{on_vary}T the corresponding relation of () is as follows：

$T_{on\_\mathrm{var}y}\left(t\right)=\frac{-R_{10}/R_9\×V_{add}}{{\mathrm{du}}_{saw}/dt}=\frac{L}{Z_r}\×\frac{V_o}{v_{in}}---\left(8\right)$

Wherein, K_MIt is the gain coefficient of multiplier, du_saw/ dt is the slope of sawtooth voltage signal, Z_rIt is characteristic impedance：L is the boost inductance value in CRM boost PFC inverter main circuit, C_ossIt is the output of switching tube Junction capacitance, C_dpIt is the parasitic capacitance value of diode；

4) pass through differential amplifier circuit, by voltage signal V_errorAnd V_addBe converted to the comparing voltage value needed for modulation wave signal V_compare, that is, have：

$V_{compare}=(1+\frac{R_{10}}{R_9})\×V_{error}-\frac{R_{10}}{R_9}\×V_{add}---\left(9\right)$

This comparing voltage value V_compareWith ON time T_onT the corresponding relation of () is as follows：

$T_{on}\left(t\right)=\frac{V_{compare}}{{\mathrm{du}}_{saw}/dt}---\left(10\right)$

5) rest-set flip-flop detects that the rising edge signal of the square-wave signal of inductive current zero cross detection circuit output confirms that switching tube is led The logical moment.Comparing voltage value V of modulation wave signal comparator positive and negative terminal_compareHand over to cut with sawtooth voltage signal and determine switching tube Turn off the moment.After switching tube is opened, sawtooth signal start from scratch linearly increasing until and V_compareWhen equal, output is opened Close pipe cut-off signals, the change ON time completing CRM boost PFC changer controls.