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CN-115347789-B - Dynamic control optimization system and method for primary side feedback control switch converter

CN115347789BCN 115347789 BCN115347789 BCN 115347789BCN-115347789-B

Abstract

The invention discloses a dynamic control optimization system and method for a primary side feedback control switch converter, wherein the dynamic control optimization system comprises a main topology circuit and a control circuit, the main topology mainly adopts a primary side feedback switch converter structure, voltage V sense of a primary side winding of the switch converter and primary winding current information I p are sampled and transmitted to the control circuit for controlling output current of the switch converter, and the control circuit comprises an output current prediction module, an output voltage sampling module, a dynamic optimization control module, a PID compensation control module and a PWM driving module, wherein the PWM driving module outputs switching signals to control the on and off of a switching tube in the main topology circuit and forms a closed loop. The invention reduces the dynamic response time, improves the dynamic response speed, and is suitable for various switching power supplies.

Inventors

  • SUN DAYING
  • WEI XINYU
  • YAO YU
  • WANG CHONG
  • GU WENHUA

Assignees

  • 南京理工大学

Dates

Publication Date
20260505
Application Date
20220819

Claims (10)

  1. 1. The dynamic control optimization system for the primary side feedback control switch converter comprises a main topology circuit adopting the primary side feedback switch converter structure, and is characterized by further comprising a control circuit, wherein the control circuit comprises an output current prediction module, an output voltage sampling module, a dynamic optimization control module, a PID compensation control module and a PWM driving module, and the dynamic control optimization system comprises the following components: The input of the output current prediction module is an auxiliary winding voltage V sense of the main topological circuit, a primary side sampling voltage V p and a switching period T s output by the PWM driving module, and the output diode average current I d is predicted and transmitted to the PID compensation control module; the output voltage sampling module samples the output voltage V o according to the auxiliary winding voltage V sense and transmits the output voltage V o to the dynamic optimization control module; The dynamic optimization control module generates an output diode average current reference value I dREF , a PID initial control parameter V pi0 after load switching and a dynamic mode variable mode_D according to the output voltage V o , and transmits the output diode average current reference value I dREF , the PID initial control parameter V pi0 and the dynamic mode variable mode_D to the PID compensation control module; The PID compensation control module generates a control parameter V pi of the next period according to the dynamic mode variable mode_D, the output diode average current reference value I dREF , the output diode average current I d and the PID initial control parameter V pi0 after load switching, and transmits the control parameter V pi to the PWM driving module; The PWM driving module determines a switching period T s of the next period and a control signal duty of a switching tube in the main topology circuit according to the control parameter V pi and primary side information of circuit topology sampling, forms a closed loop with the main topology circuit, and inputs the switching period T s to the output current prediction module.
  2. 2. The dynamic control optimization system for a primary-side feedback control switching converter of claim 1, wherein the output current prediction module outputs a diode average current I d that is: Wherein R p represents primary sampling resistance, N p and N s represent turns of primary winding and secondary winding of the transformer, V p_peak represents primary peak voltage, T s represents switching period, T r represents demagnetizing time, and the demagnetizing time is determined by comparing auxiliary winding voltage V sense with 0 voltage.
  3. 3. A dynamic control optimization system for a primary feedback controlled switching converter in accordance with claim 1 wherein the output voltage V o is related to the auxiliary winding voltage V sense by: Wherein, R 1 and R 2 represent voltage dividing resistance values at two ends of the auxiliary winding, N a and N s represent turns of the auxiliary winding and the secondary winding of the transformer, the moment I s is reduced to 0 is taken as a sampling point, and V sense_sampling is the voltage dividing of the auxiliary winding at the sampling moment.
  4. 4. The dynamic control optimization system for a primary feedback control switching converter according to claim 1, wherein the dynamic optimization control module comprises a dynamic detection module, a parameter calculation module and an optimization control module, wherein the dynamic detection module is input into an output voltage V o and a pre-estimated steady-state output voltage V o_stable2 after load switching, the modules are used for determining a dynamic mode variable mode_D, the parameter calculation module is input into an output voltage V o and a dynamic mode variable mode_D, the modules are used for determining a PID initial control parameter V pi0 after load switching and a pre-estimated steady-state output voltage V o_stable2 after load switching, and the optimization control module is input into a dynamic mode variable mode_D, and the modules are used for determining a diode average current reference value I dREF .
  5. 5. The dynamic control optimization system for a primary-side feedback controlled switching converter of claim 4 wherein said dynamic detection module determining a dynamic mode variable mode_d comprises: Determining a steady state output voltage upper limit V omax and a steady state output voltage lower limit V omin ; V omax ＝V o_stable1 +ΔV 1 V omin ＝V o_stable1 -ΔV 2 Wherein Δv 1 and Δv 2 are voltages related to system parameters, and V o_stable1 is an average value of output voltages of N periods; When the converter is in a normal working mode, a dynamic mode variable mode_D is set to 0, if the output voltage is higher than V omin and lower than V omax , the converter is still in the normal working mode, the mode_D is kept to 0, if the output voltage V o is higher than or equal to V omax , the output voltage V o is increased, the mode_D is set to 1, and if the output voltage V o is lower than or equal to V omin , the output voltage V o is decreased, and the mode_D is set to 2; When the converter is in the dynamic working mode, if the mode_D is 1, the converter exits the dynamic working mode and returns to the normal working mode when the detected output voltage is greater than or equal to the estimated steady-state output voltage V o_stable2 after the load is switched, and the mode_D is set to 0, and if the mode_D is 2, the converter exits the dynamic working mode and returns to the normal working mode when the detected output voltage is less than or equal to the estimated steady-state output voltage V o_stable2 after the load is switched, and the mode_D is set to 0.
  6. 6. The system of claim 4, wherein the parameter calculation module determines a PID initial control parameter V pi0 after load switching and an estimated steady state output voltage V o_stable2 after load switching specifically comprises: When the mode_D is switched from 0 to 1 or 2, the current time is recorded as t 1 , the output voltage V o at the moment is recorded as V o (t 1 ), a known time interval Deltat 1 is passed from the time of t 1 , the output voltage V o at the moment is recorded as V o (t 2 at the time of t 2 ＝t 1 +Δt 1 , a known time interval Deltat 2 is passed from the time of t 2 , namely the output voltage V o at the moment is recorded as V o (t 3 at the time of t 3 ＝t 2 +Δt 2 , and the steady-state output voltage V o_stable2 is estimated after the load is switched to be: Wherein I REF is the output current, R 2 is the load impedance, i.e Wherein C represents an output capacitance; The primary side peak voltage V peak0 after load switching is: Wherein, L p represents primary excitation inductance, eta represents transmission efficiency, T s0 ＝T s , and PID initial control parameter V pi0 ＝V peak0 after load switching is set.
  7. 7. The system of claim 4 wherein the optimizing control module determines the diode average current reference value I dREF to include the output diode average current reference value I dREF as the target reference current I REF when mode_D is 0, the output diode average current reference value I dREF as the current I d_high when mode_D is 1, wherein I d_high ＝I REF +ΔI 1 , the parameter ΔI 1 is based on the system parameter value, and the output diode average current reference value I dREF as the current I d_low ,I d_low ＝I REF -ΔI 2 ,ΔI 2 is based on the system parameter value when mode_D is 2.
  8. 8. The system of claim 1, wherein the PID compensation control module generates the control parameter V pi for the next cycle by recording the mode variable of the next switching cycle as mode_D_pre, if mode_D_pre is 1 or 2 and mode_D is 0, the control parameter V pi is equal to the PID initial control parameter V pi0 after load switching, otherwise, subtracting the output diode average current reference value I dREF from the output diode average current I d to obtain an error e (n), and calculating a new compensation value V pi by PID compensation control based on the value of e (n).
  9. 9. The dynamic control optimization system for a primary-side feedback controlled switching converter of claim 1 wherein the PWM drive module uses a peak current control method to determine the switching period T s and the control signal duty of the switching tubes in the main topology.
  10. 10. A method for a dynamic control optimization system for a primary side feedback controlled switching converter based on any of claims 1-9, comprising the steps of: The output current prediction module predicts the average current I d of the output diode based on the auxiliary winding voltage V sense of the main topology circuit, the primary side sampling voltage V p and the switching period T s output by the PWM driving module and transmits the average current I d to the PID compensation control module; The output voltage sampling module samples the output voltage V o according to the auxiliary winding voltage V sense and transmits the output voltage V o to the dynamic optimization control module; The dynamic optimization control module generates an output diode average current reference value I dREF , a PID initial control parameter V pi0 after load switching and a dynamic mode variable mode_D according to the output voltage V o , and transmits the output diode average current reference value I dREF , the PID initial control parameter V pi0 and the dynamic mode variable mode_D to the PID compensation control module; The PID compensation control module generates a control parameter V pi of the next period according to the dynamic mode variable mode_D, the output diode average current reference value I dREF , the output diode average current I d and the PID initial control parameter V pi0 after load switching, and transmits the control parameter V pi to the PWM driving module; The PWM driving module determines and outputs a switching period T s of the next period and a control signal duty of a switching tube in the main topology circuit according to the control parameter V pi and primary side information of circuit topology sampling, forms a closed loop with the main topology circuit, and inputs the switching period T s to the output current prediction module; and repeating the steps to control the switching converter in the main topology circuit.

Description

Dynamic control optimization system and method for primary side feedback control switch converter Technical Field The invention relates to dynamic control of a control switch converter, in particular to a dynamic control optimization system and method for a primary side feedback control switch converter. Background In recent years, with the development of low-power electronic devices, offline power-based chargers and adapters have been widely used, and the design of low-cost and low-power-consumption switching power supplies has become a research hotspot in recent years. The common offline switching power supply mainly comprises a flyback converter, a forward converter, a half-bridge converter, a full-bridge converter and the like, wherein the flyback converter is widely applied to low-power electronic equipment due to the advantages of simple circuit structure, low cost, good isolation and the like. According to different control modes, the flyback converter can be controlled by two methods, namely primary side feedback and secondary side feedback. The secondary side feedback method mainly adopts an optical coupler device between the input end and the output load end of the transformer to convert the output electric signal into an optical signal for transmission, and finally converts the optical signal into an electric signal for input into a control module. The control mode has good real-time performance, but components such as the optical coupler are added, the circuit complexity is increased, and the optical coupler is easy to age and is easily affected by temperature, so that the reliability and the service life of the power supply are reduced. The primary feedback method generally introduces an auxiliary winding, indirectly realizes output voltage or current control based on auxiliary winding voltage information, has no optocoupler in a primary feedback circuit, and improves the integration level of the circuit. Because the output current cannot be directly sampled, the output constant current control of the traditional primary feedback flyback converter is mainly realized by keeping the average current I dREF of an output diode constant, the output winding and the output diode are equivalent to a constant current source with the current I dREF for supplying power to an output load and an output capacitor, and in the dynamic process, the output voltage meets the following conditions through the analysis of an output equivalent circuit: The output current satisfies: Wherein, R 1 represents the load resistance before switching, R 2 represents the load resistance after switching, and C represents the output capacitance. The output current and output voltage change exponentially to return to a stable value, and the dynamic response time is only related to the time constant τ, i.e. the product of the output capacitance C and the switched load resistance R 2. Compared with a secondary side feedback method, the primary side feedback method cannot directly sample the current information of the output end, and the response time in the dynamic process is long, so that the research on a dynamic optimization control strategy of the primary side feedback constant current control switching power supply is necessary. The existing method for improving the primary side feedback dynamic response mainly aims at a system with unchanged output voltage, the output voltage is quickly stabilized by changing the input power, and the working mode is judged according to the change slope of the output voltage so as to eliminate the voltage overshoot, but the method is not suitable for a constant current converter with changed output voltage. Disclosure of Invention Based on the analysis, the invention provides a dynamic control optimization system and a method for a primary side feedback control switch converter, which are applicable to various switch converters, reduce dynamic response time and improve dynamic response speed. The technical solution for realizing the purpose of the invention is as follows: A dynamic control optimization system for a primary side feedback control switch converter comprises a main topology circuit and a control circuit, wherein the main topology mainly adopts a primary side feedback switch converter structure, voltage V sense of a primary side winding of the switch converter and primary winding current information I p are sampled and transmitted to the control circuit to control output current of the switch converter, and the control circuit comprises an output current prediction module, an output voltage sampling module, a dynamic optimization control module, a PID compensation control module and a PWM driving module, wherein the PWM driving module outputs a switching signal to control on and off of a switching tube in the main topology circuit and forms a closed loop. Further, the proposed output current prediction module, whose input signal is the primary winding voltage V sense of the converte