Control method for improving dynamic response of switch power
地域：
Nanjing
摘要
A control method for improving dynamic response of switch power is based on a closed-loop control system comprising a sampling module, a dynamic control module, an error calculation module, a PID module, a mode control module, and a PWM module. The sampling module samples an output voltage Vo, and the dynamic control module compares the output voltage Vo with a set maximum voltage Vomax, a set minimum voltage Vomin, and a reference voltage Vref, so as to determine whether to adopt a dynamic mode. In the dynamic mode, when the output voltage Vo changes greatly, the output voltage Vo is rapidly restored to a stable voltage by inputting large power or small power.
說明書
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This application is the U.S. national phase of International Application No. PCT/CN2016/072693 filed on 29 Jan. 2016 which designated the U.S. and claims priority to Chinese Application No. CN201510502980.X filed on 14 Aug. 2015, the entire contents of each of which are hereby incorporated by reference.
The present invention relates to switch power, and more particularly, to a control method for improving dynamic response of switching power supply
Switch power is usually used as a power supply for all types of electric equipment, to play a role of converting an unadjusted AC or DC input voltage into an adjusted AC or DC output voltage. Since the switch power needs to adapt to different working conditions, the performance requirements on the dynamic response of the power are higher and higher. Good dynamic effects require small voltage changes and the voltage recovery time. For example, in the application of home appliances, the power load of a washing machine changes quickly and greatly, so that overvoltage and undervoltage are introduced into the output voltage of the power, and when the overvoltage and undervoltage are too large, the load damage to the washing machine is relatively larger; in addition, in mobile phone charging, when a charger is standby and the mobile phone is loaded suddenly, the output voltage is reduced, and when the voltage is reduced under the normal voltage of a battery, there is a certain damage to the battery. Therefore, the dynamic performance needs to be increased.
權(quán)利要求
What is claimed is:1. A control method for improving dynamic response of switch power, wherein the control method is based on a control system comprising a sampling module, a dynamic control module, an error calculation module, a PID module, a mode control module, and a PWM module, and the control system is connected to the controlled switch power to form a closed loop;the sampling module comprises a sampling circuit and a sampling calculation module, the sampling circuit outputs a partial voltage through the switch power to obtain the information of the output voltage, and the sampling calculation module calculates the output voltage as Vo according to the result of the sampling circuit; the dynamic control module comprises a voltage monitoring module and a slope calculation module; the voltage monitoring module receives the sampling result of the output voltage Vo outputted by the sampling module and determines whether to adopt a dynamic mode according to the relationship between Vo and a set maximum voltage Vomax, a set minimum voltage Vomin, and a reference voltage Vref respectively, wherein Vomin<Vref<Vomax; the dynamic mode means that when the output voltage Vo changes greatly, the output voltage Vo is rapidly restored to a stable voltage by inputting large power or small power, and the dynamic mode comprises a constant-frequency light-to-heavy load LTH mode and a constant-frequency heavy-to-light load HTL mode; the voltage monitoring module outputs a mode selection result mode_F to the mode control module and the slope calculation module, if the voltage monitoring module determines that the system enters the dynamic mode, the slope calculation module calculates a voltage change slope; if the system enters a normal working mode, output latch of the slope calculation module is controlled to be unchanged; the slope calculation module calculates the rising slope of Vo when the voltage monitoring module outputs the LTH mode, and calculates the descending slope of Vo when the voltage monitoring module outputs the HTL mode; when the normal working mode is adopted, the slope calculation module does not calculate the slope, and the slope Kslope keeps unchanged; and the result Kslope of the slope calculation module is outputted to the mode control module; the voltage monitoring module comprises three comparators COMP1, COMP2 and COMP3, and a logical unit, the positive terminal of the comparator COMP1 is connected to the set maximum Vo Vomax, and the negative terminal of the comparator COMP1 is connected to Vo; the positive terminal of the comparator COMP2 is connected to Vo, and the negative terminal of the comparator COMP2 is connected to the set reference voltage Vref; the positive terminal of the comparator COMP3 is connected to Vo, the negative terminal of the comparator COMP3 is connected to the set minimum voltage Vomin, and the logical unit outputs one of the LTH mode, the HTL mode and the normal mode according to the results of the three comparators; when Vo is less than the minimum voltage Vomin, the logical unit outputs the constant-frequency light-to-heavy load LTH mode in the dynamic mode to enable the output to be rapidly raised to the reference voltage Vref by inputting large power and then jump out of the mode and enter the normal mode, and the initial state of the normal mode is set by the mode control module; when Vo is greater than the maximum voltage Vomax, the logical unit outputs the constant-frequency heavy-to-light load HTL in the dynamic mode to enable the output to be rapidly dropped to the reference voltage Vref by inputting small power and then jump out of the mode and enter the normal mode, and the initial state of the normal mode is set by the mode control module; if Vo does not change greatly, the dynamic mode is not needed, and loop control is realized through normal PI control method and mode control, which is called normal working mode; when Vo is between Vomin and Vref, if the output of the logical unit is the LTH mode in last period, then the output of the logical unit is the LTH mode in the period; if the output of the logical unit is the HTL mode in last period, then the output of the logical unit is the normal mode in the period; if the output of the logical unit is the normal mode in last period, then the output of the logical unit is the normal mode in the period; when Vo is between Vref and Vomax, if the output of the logical unit is the LTH mode in last period, then the output of the logical unit is the normal mode in the period; if the output of the logical unit is the HTL mode in last period, then the output of the logical unit is the HTL mode in the period; and if the output of the logical unit is the normal mode in last period, then the output of the logical unit is the normal mode in the period; the inputs of the slope calculation module are the sampling result Vo and the output mode_F of the voltage monitoring module, when the mode_F is the LTH mode, the rising slope Kup of Vo is calculated, and the voltage changes of N1 LTH mode switch periods are used for equivalency replacement, i.e., Kup=Vo(n)?Vo(n?N1), wherein Vo(n) is the sampling result of the current period, Vo(n?N1) is the sampling result before N1 periods, and Kup is the size of the result Kslope outputted from the slope calculation module; when the mode_F is the HTL mode, the descending slope Kdown of Vo is calculated, the voltage changes of N2 HTL mode switch periods are used for equivalency replacement, i.e., Kdown=Vo(n?N2)?Vo(n), wherein Kdown is the size of Kslope outputted; and when the mode_F is the normal mode, the slope calculation module does not work, and the output result Kslope keeps unchanged through latching; the input of the error calculation module is the output Vo of the sampling module, and the difference of subtracting the output voltage Vo from the reference voltage Vref is the current sampling error, which is donated as e1, and outputted to the PID module; the inputs of the mode control module are the output mode_F of the voltage monitoring module, the output Kslope of the slope calculation module and the calculation result VPI of the PID module respectively; when the output mode_F of the voltage monitoring module is the dynamic mode, the mode control module switches off the PID module through outputting a control signal PI_ctrl, and controls the PWM module to receive the switching period Ts_LTH or Ts_HTL of the dynamic mode and duty ratio DLTH/current or DHTL/current information outputted by the mode control module, and the PWM module generates a duty ratio waveform at the moment according to the Ts_LTH or Ts_HTL of the dynamic mode, and the duty ratio DLTH/current or DHTL/current information; when the mode control module jumps out of the dynamic mode to enter a first switch period of the normal working mode, the mode control module obtains the size of a corresponding output load according to the size of the slope Kslope of the slope calculation module at the moment, the PID module is started through the control signal PI_ctrl and VPI0 is assigned to the current sampling result before PID calculation, VPI0 is the output value of the PID module corresponding to the load in a stable state after change, the PID module conducts PID calculation according to the error outputted by the error calculation module after the assignment, and a PID calculation result VPI is fed back to the mode control module to conduct mode selection and control in the normal working mode; when the mode control module jumps out of the dynamic mode to enter a second switch period of the normal working mode and later, the PID module is started by PI_ctrl to conduct calculation, the PID module conducts PID calculation according to the error outputted by the error module, the calculation result VPI is fed back to the mode control module to conduct mode selection and control in the normal working mode, the PWM module receives a supplementary result VPI outputted by the PID and the control mode of the normal working mode given by the mode control module in the normal working mode, the control mode is donated as mode_ctrl, the switch period and the duty ratio/current information is obtained through calculation, and the PWM module generates the duty ratio waveform according to the switch period and a duty ratio signal at the moment; the inputs of the PID module are an error signal e1 outputted by the error calculation module, the control signal PI_ctrl outputted by the mode control module and the VPI0 assigned; in the dynamic mode, when the PID module is switched off, the dynamic mode is switched to the first switch period of the normal working mode, an initial value VPI0 is assigned to the calculation of the PID module firstly, then PID calculation is conducted, the supplementary calculation result VPI is outputted to the mode control module and the PWM module, then PID calculation is conducted to each period of the normal working mode, and the supplementary result VPI is outputted to the mode control module and the PWM module; and the inputs of the PWM module are the PI_ctrl control signal outputted by the mode control module, the switch period Ts_LTH or Ts_HTL and the duty ratio DLTH or DHTL of the LTH and HTL modes, the control mode result mode_ctrl of the mode control module in the normal working mode, and the supplementary result VPI of the PID module; the switch period and the duty ratio information in normal control are obtained by calculating through the supplementary result VPI of the PID module and a control mode mode_ctrl signal of the normal working mode given by the mode control module, after the period and the duty ratio/peak current information are obtained, the duty ratio waveform is outputted through a driving circuit to realize the loop control on the grid of a power valve of the switch power; and then the output voltage of the switch power is sampled again, and the process above is repeated to conduct cycle control to switch on and off the power valve of the switch power, so as to make the system be more stable, thus obtaining higher dynamic response.
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