Inverse time limit retraction current limiting method and high-frequency switching power supply

Abstract

The invention relates to an inverse time limit retraction current limiting method and a high-frequency switching power supply, and the method comprises the steps: fusing a voltage given function and a current fast loop controller after a short-circuit fault of target equipment, and obtaining the output of a voltage loop controller; the phenomenon that current loop protection is interfered due to the fact that the instantaneous given value of the voltage loop is too large at the moment of opening the driving moment of the target equipment is effectively avoided; the voltage loop controller outputs voltage, the current slow loop controller outputs are accessed to obtain current slow loop controller outputs, the voltage loop controller outputs and the current slow loop controller outputs are reduced, and safe and stable current values are output, so that potential safety hazards caused by control lag are reduced, and output of the current loop and the voltage loop in a short-circuit circuit is efficiently controlled. And safe and rapid protection is realized after the target equipment is short-circuited.

Description

Technical Field

[0001] The invention relates to an inverse time-limited retraction current limiting method and a high-frequency switching power supply, belonging to the field of circuits. Background Art

[0002] Circuit short circuit is the most common and most extreme circuit fault. When the circuit produces an extreme overcurrent state, current limiting protection is often performed through the following three methods:

[0003] 1. When high-power equipment is in an overcurrent state, in order to protect the safety of the equipment, a forced shutdown method will be adopted for overcurrent protection. Specifically, when it is detected that the sampling current is greater than the short-circuit current threshold, the short-circuit fault flag is triggered, the control system handles the short-circuit fault, and shuts down the power device, thereby being able to simply and effectively protect the high-power equipment. However, this method cannot automatically restore the normal working state of the high-power equipment when the short-circuit fault is eliminated. It needs to be powered off and restarted before it can continue to work normally, causing power loss to the electrical equipment.

[0004] 2. For the first protection method, the second protection method adds a recovery function after the fault is eliminated on the basis of forced shutdown. Specifically, when it is detected that the sampling current is greater than the short-circuit current threshold, the short-circuit fault flag is triggered, and the control system processes the short-circuit fault and shuts down the power device; then, the output voltage is judged. If the output voltage returns to normal, the device is turned on for normal operation; if the output voltage returns to abnormal, the drive continues to be blocked, thereby solving the problem that the device cannot automatically resume normal working state after the short-circuit fault is eliminated. However, in this way, the output time of the device is longer, and it is impossible to restore the device immediately after output.

[0005] 3. For the second protection method, the third protection method adds a fast fault recovery function on the basis of forced shutdown and recovery after the fault is eliminated. Specifically, when it is detected that the sampling current is greater than the short-circuit current threshold, the short-circuit fault flag is triggered and the power device is turned off; at the same time, it is judged whether the output voltage is normal. If the output voltage is normal, the normal working state is restored; if the output voltage is abnormal, it works in the current limiting state, so as to quickly protect and recover quickly. However, the voltage gain is zero during a short circuit. When the power device is turned on, there will be a large current shock, causing damage to the power device, and the real-time control requirements are high. It is easy to have a loop response lag, resulting in excessive stress on the power device. Summary of the invention

[0006] The purpose of the present invention is to provide an inverse time-limited retractive current limiting method and a high-frequency switching power supply, so as to solve the problem that the instantaneous current after the power device is turned on under a short-circuit fault causes damage to the power device and control lags, so as to achieve rapid response and protection to the short-circuit fault, and to restore the normal working state safely, reliably, quickly and automatically after the short-circuit fault is eliminated.

[0007] To achieve the above object, on the one hand, the solution of the present invention proposes an inverse time-limited retraction current limiting method, the method comprising:

[0008] In response to a short circuit fault of the target device, determining a current slow loop controller setting and a current fast loop controller setting;

[0009] Using the voltage setting function, the set voltage setting value with slow climbing is obtained;

[0010] The current fast loop controller setting is used as the input of the current fast loop controller, and the current fast loop controller output is obtained by combining the current feedback value;

[0011] The smaller value of the voltage set value and the current fast loop controller output is taken as the input of the voltage loop controller, and the voltage loop controller output is obtained by combining the voltage feedback value;

[0012] The current slow loop controller setting is used as the input of the current slow loop controller, and the current slow loop controller output is obtained by combining the current feedback value;

[0013] The smaller value of the voltage loop controller output and the current slow loop controller output is used to generate a drive signal for controlling the power device.

[0014] Furthermore, the voltage given function is:

[0015] V (ref) = VT;

[0016] Among them, V (ref) is the voltage given value; V is the voltage given per unit time; T is the voltage given time.

[0017] Furthermore, the current fast loop controller setting and the current slow loop controller setting satisfy the following relationship:

[0018]

[0019] in, is given by the current fast loop controller; is the current slow loop controller given; I Offset is the current bias.

[0020] Furthermore, the inverse time-limited retraction current limiting method further comprises:

[0021] Continuously collect current feedback values ​​for at least two sampling cycles;

[0022] When the current feedback values ​​of all sampling cycles are greater than the preset short-circuit current threshold, it is determined that the target device has a short-circuit fault.

[0023] Furthermore, the inverse time-retracting current limiting method further includes: in response to a short circuit fault of the target device, limiting the current by a voltage loop controller.

[0024] On the other hand, the present application also provides a high-frequency switching power supply, including a controller, wherein the controller executes instructions to implement the following method steps:

[0025] In response to a short circuit fault of the target device, determining a current slow loop controller setting and a current fast loop controller setting;

[0026] Using the voltage setting function, the set voltage setting value with slow climbing is obtained;

[0027] The current fast loop controller setting is used as the input of the current fast loop controller, and the current fast loop controller output is obtained by combining the current feedback value;

[0028] The smaller value of the voltage set value and the current fast loop controller output is taken as the input of the voltage loop controller, and the voltage loop controller output is obtained by combining the voltage feedback value;

[0029] The current slow loop controller setting is used as the input of the current slow loop controller, and the current slow loop controller output is obtained by combining the current feedback value;

[0030] The smaller value of the voltage loop controller output and the current slow loop controller output is used to generate a drive signal for controlling the power device.

[0031] Furthermore, the voltage given function is:

[0032] V (ref) = VT;

[0033] Among them, V (ref) is the voltage given value; V is the voltage given per unit time; T is the voltage given time.

[0034] Furthermore, the current fast loop controller setting and the current slow loop controller setting satisfy the following relationship:

[0035]

[0036] in, is given by the current fast loop controller; is the current slow loop controller given; I Offset is the current bias.

[0037] Furthermore, the high-frequency switching power supply further comprises:

[0038] Continuously collect current feedback values ​​for at least two sampling cycles;

[0039] When the current feedback values ​​of all sampling cycles are greater than the preset short-circuit current threshold, it is determined that the target device has a short-circuit fault.

[0040] Furthermore, the high-frequency switching power supply further comprises: in response to a short-circuit fault of the target device, in response to the short-circuit fault of the target device, limiting the amplitude through a voltage loop controller.

[0041] The beneficial effects of the present invention are as follows: in response to a short-circuit fault of a target device, a voltage given function is used to steadily ramp up the voltage in a voltage loop, effectively avoiding interference with the current loop protection caused by an excessively large instantaneous given value of the voltage loop at the moment of opening the driving of the target device, and then integrating a current fast loop controller so that it is input together with the voltage given value into the voltage loop controller to obtain the output of the voltage loop controller, and continuing to intervene in a current slow loop controller to obtain the output of the current slow loop controller, minimizing the output of the voltage loop controller and the output of the current slow loop controller to ensure that the final output is stable, safe, and suitable for the current value of the current short-circuit circuit, reducing the potential safety hazards caused by control lag, and realizing the control of the output of the current loop and the voltage loop in the short-circuit circuit, so as to achieve safe and rapid equipment protection after the target device is short-circuited. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flow chart of an inverse time-limited retraction current limiting method according to one aspect of the present application;

[0043] Figure 2 It is a flow chart of an inverse time-limited retraction current limiting method in an actual application scenario according to one aspect of the present application. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail in a clear and complete manner in conjunction with the accompanying drawings and embodiments.

[0045] The idea of ​​the present invention is to use a voltage setting function to set a slowly rising voltage setting value, so as to effectively avoid interference caused by an excessively large instantaneous voltage setting value when the drive is turned on; a current fast loop controller and a current slow loop controller are introduced to control the current value in the short-circuit circuit, so that after a large current impact occurs during a short circuit, the circuit can perform current limiting protection in the fastest time, thereby forming a short-circuit recovery system for a high-frequency switching power supply that can protect the safe recovery of the target equipment and respond quickly and sensitively to flexibly control the current and voltage.

[0046] Embodiment 1:

[0047] like Figure 1 , is a flow chart of an inverse time-limited retraction current limiting method according to one aspect of the present application, wherein the method comprises steps S11 to S16, specifically:

[0048] Step S11, in response to a short circuit fault of the target device, determine the current slow loop controller given and the current fast loop controller given; it should be noted that in response to a short circuit fault of the target device, the target device is also blocked and driven for one cycle, and at the same time, the output amplitude is limited by the voltage loop controller, and the current slow loop controller given and the current fast loop controller given are assigned.

[0049] In addition, the current fast loop controller setting and the current slow loop controller setting satisfy the following relationship:

[0050]

[0051] in, is given by the current fast loop controller; is given by the current slow loop controller; I offset is the current bias; here, the current bias is used to adjust the current protection value of the circuit, which is set according to the circuit requirements, equipment characteristics, power supply voltage and other parameters.

[0052] In order to avoid the voltage loop interfering with the current loop control and causing current overshoot at the moment of opening the blocking drive, in step S12, a voltage setting function is used to obtain a set voltage setting value that rises slowly; here, the voltage setting function is:

[0053] V (ref) = VT;

[0054] Among them, V (ref) is the voltage given value; V is the voltage given per unit time; T is the voltage given time, so that the voltage loop is given to climb, so that the instantaneous given value of the voltage loop will not affect the current loop.

[0055] In order to avoid the control lag of the target device, in step S13, the current fast loop controller is given as the input of the current fast loop controller, and the current fast loop controller output is obtained by combining the current feedback value; it should be noted that the controller includes but is not limited to a PI (Proportional Integral controller) controller, wherein the output formula corresponding to the PI controller is:

[0056] u(t)=K p e(t)+K i ∫e(t)dt;

[0057] Among them, u(t) is the output control signal; e(t) is the deviation at the current moment; K p is the proportional gain; K iis the integral gain; ∫e(t)dt is the integral term of the error. Specifically, when the current fast-loop PI controller is inserted, e(t) is the deviation between the current feedback value and the setting of the current fast-loop controller.

[0058] At the same time, the feedback value will be continuously used in the PI controller to calibrate the output value. That is to say, an output value calibration loop is formed in the PI controller. Specifically: in any cycle, the error between the output value of the previous cycle and the given value is calculated, and the current output value is determined while reducing the error. Then, the current output value is used as the feedback value of the output value calculation process of the next cycle to calibrate the output value of the next cycle, and the output value is continuously corrected until the error reaches the ideal error value.

[0059] In step S14, the smaller value of the voltage set value and the current fast loop controller output is taken as the input of the voltage loop controller, and the voltage loop controller output is obtained by combining the voltage feedback value; here, when the voltage loop PI controller is intervened, e(t) is the deviation between the smaller value (the smaller value of the voltage set value and the current fast loop controller output) and the voltage feedback value.

[0060] Step S15, the current slow loop controller setting is used as the input of the current slow loop controller, and the current slow loop controller output is obtained by combining the current feedback value; here, when the current slow loop PI controller is intervened, e(t) is the deviation between the current feedback value and the current slow loop controller setting.

[0061] Step S16, taking the smaller value of the voltage loop controller output and the current slow loop controller output to generate a drive signal for controlling the power device; here, in an actual application scenario, after the drive signal for controlling the power device is output, the output current during short circuit is controlled by turning on and off the power device.

[0062] Through steps S11 to S16, the voltage setting function is used to output a safe given voltage value; by adding current bias and current fast loop controller, when the output current is too large, the current fast loop can intervene in the control first and output a higher protection current value to protect the equipment from damage. When the fast loop output is stable, the current slow loop controller intervenes in the control and outputs a safe and stable current value to avoid safety hazards caused by control lag.

[0063] In a preferred embodiment of the present application, in response to a short circuit fault in the target device A, the target device A blocks the drive for one cycle, and at the same time, limits the voltage loop output amplitude, and generates I_Slow_Ref (current slow loop controller given) and I_Fast_Ref (current fast loop controller given) by using the satisfied relationship between the current fast loop controller given and the current slow loop controller given; calls the voltage given function to output a slowly rising voltage given value U X; Input I_Fast_Ref and I_Fed (current feedback value) to the current fast loop PI controller, not only correct the output value of the current fast loop PI controller, until the current fast loop PI controller outputs I1 when the error is optimal; take the voltage set value U X The smaller value of the current fast loop PI controller output I1 is used as the input of the voltage loop PI controller. Within the limit of the voltage loop output amplitude, V_Fed (voltage feedback value) is continuously input to correct the output value until the voltage loop PI controller outputs U X1 (voltage loop controller output); insert the current slow loop PI controller, and input I_Slow_Ref and I_Fed (current feedback value), through continuous error calculation, get the current slow loop PI controller output I2 when the error is optimal; compare I2 with U X1 The output signal is minimized and the driving signal for controlling the power device is output, and the output current of the short-circuit circuit is controlled by turning on and off the power device.

[0064] Embodiment 2:

[0065] In another aspect of the present application, an inverse time-limited retraction current limiting method is proposed, which further includes:

[0066] The current feedback value of at least two sampling cycles is continuously collected; here, the current feedback value refers to the output current value in the current circuit.

[0067] When the current feedback value of all sampling cycles is greater than the preset short-circuit current threshold, the target device is deemed to have a short-circuit fault. Here, the preset short-circuit current threshold can be set according to different target devices and different circuit requirements, effectively avoiding the occurrence of short-circuit misjudgment.

[0068] For example, the short-circuit current threshold of the preset target device B is I_Max; the system detects a short-circuit fault in the target device B, and sequentially obtains the current feedback values ​​(i.e., I_fed1, I_fed2, and I_fed3) in the T1 sampling period, the T2 sampling period, and the T3 sampling period; I_fed1 and I_Max are judged in T1, I_fed2 and I_Max are judged in T2, and I_fed3 and I_Max are judged in T3. When I_fed1>I_Max and I_fed2>I_Max and I_fed3>I_Max, it is determined that a short-circuit fault occurs in the target device B.

[0069] Embodiment 3:

[0070] like Figure 2As shown, it is a flow chart of an inverse time-limited retractive current limiting method in an actual application scenario of one aspect of the present application, wherein, first, at the moment of a short-circuit fault in the equipment, an impact current will appear in the power circuit, and the short-circuit judgment module detects the output current I_fed in the circuit. To avoid misjudgment of a short circuit, the short-circuit judgment module continuously detects the output current I_fed of three sampling cycles. When the output current of the three sampling cycles is greater than the preset short-circuit current threshold, the system triggers the short-circuit instruction of Short_Cir_Flag=1, and determines that the equipment is short-circuited.

[0071] Next, in response to the short-circuit instruction of the device short circuit, the voltage loop output amplitude is limited, and based on the relationship between the current fast loop controller given and the current slow loop controller given, I_Slow_Ref and I_Fast_Ref are obtained; at the same time, the set voltage given function is used to obtain a slowly climbing voltage given value so that the voltage loop no longer interferes with the control of the current loop.

[0072] Then, I_Fast_Ref and I_fed are simultaneously input into the current fast loop controller, and the calculation formula of the PI controller is used to correct the output value of the current fast loop controller until the output of the current fast loop controller is obtained when the error is optimal; the smaller value between the output of the current fast loop controller and the voltage given value is taken and determined as the input of the voltage loop controller; the voltage loop controller receives the smaller value between the output of the current fast loop controller and the voltage given value and V_fed on the basis of limiting the output amplitude of the voltage loop, and continuously performs the correction cycle of the output value in the voltage loop controller to obtain the output V_out of the voltage loop controller. I_Slow_Ref is used as the input of the current slow loop controller, and I_fed is also input into the current slow loop controller. The calculation formula of the PI controller is used to continuously perform the correction cycle of the output value in the current slow loop controller to obtain the output of the current slow loop controller.

[0073] Finally, the smaller of the voltage loop controller output V_out and the current slow loop controller output is taken to output SPWM (Sinusoidal Pulse Width Modulation) that controls the power device, thereby controlling the output current during short circuit by turning the power device on and off.

[0074] At the same time, on the other hand, the present application also provides a high-frequency switching power supply, including a controller, wherein the controller executes the above-mentioned inverse time-limited retraction current limiting method to realize the current limiting protection of the high-frequency switching power supply device, improve the stress resistance of the high-frequency switching power supply to the circuit short circuit, and increase the service life of the high-frequency switching power supply. Here, the embodiment of the high-frequency switching power supply please refer to the embodiment of the above-mentioned inverse time-limited retraction current limiting method, which will not be repeated here.

Claims

1. An inverse time-limited retraction current limiting method, characterized in that: The method comprises: In response to a short circuit fault of the target device, determining a current slow loop controller setting and a current fast loop controller setting; Using the voltage setting function, the set voltage setting value with slow climbing is obtained; The current fast loop controller setting is used as the input of the current fast loop controller, and the current fast loop controller output is obtained by combining the current feedback value; The smaller value of the voltage set value and the current fast loop controller output is taken as the input of the voltage loop controller, and the voltage loop controller output is obtained by combining the voltage feedback value; The current slow loop controller setting is used as the input of the current slow loop controller, and the current slow loop controller output is obtained by combining the current feedback value; The smaller value of the voltage loop controller output and the current slow loop controller output is used to generate a drive signal for controlling the power device.

2. According to the inverse time-limited retractive current limiting method of claim 1, the voltage given function is: in, is the voltage given value; V is the voltage given per unit time; T is the voltage given time.

3. The inverse time-limited retraction current limiting method according to claim 1, characterized in that: The relationship between the current fast loop controller setting and the current slow loop controller setting is as follows: in, is given by the current fast loop controller; is given by the current slow loop controller; Current bias.

4. The inverse time-limited retraction current limiting method according to claim 1, characterized in that: Also includes: Continuously collect current feedback values ​​for at least two sampling cycles; When the current feedback values ​​of all sampling cycles are greater than the preset short-circuit current threshold, it is determined that the target device has a short-circuit fault.

5. The inverse time-limited retraction current limiting method according to claim 1, characterized in that: Also includes: In response to a target device short circuit fault, the voltage is limited by a voltage loop controller.

6. A high frequency switching power supply, characterized in that: The method comprises a controller that executes instructions to implement the following method steps: In response to a short circuit fault of the target device, determining a current slow loop controller setting and a current fast loop controller setting; Using the voltage setting function, the set voltage setting value with slow climbing is obtained; The current fast loop controller setting is used as the input of the current fast loop controller, and the current fast loop controller output is obtained by combining the current feedback value; The smaller value of the voltage set value and the current fast loop controller output is taken as the input of the voltage loop controller, and the voltage loop controller output is obtained by combining the voltage feedback value; The current slow loop controller setting is used as the input of the current slow loop controller, and the current slow loop controller output is obtained by combining the current feedback value; The smaller value of the voltage loop controller output and the current slow loop controller output is used to generate a drive signal for controlling the power device.

7. The high-frequency switching power supply according to claim 6, wherein the voltage given function is: in, is the voltage given value; V is the voltage given per unit time; T is the voltage given time.

8. The high-frequency switching power supply according to claim 6, characterized in that: The relationship between the current fast loop controller setting and the current slow loop controller setting is as follows: in, is given by the current fast loop controller; is given by the current slow loop controller; is the current bias.

9. The high-frequency switching power supply according to claim 6, characterized in that: Also includes: Continuously collect current feedback values ​​for at least two sampling cycles; When the current feedback values ​​of all sampling cycles are greater than the preset short-circuit current threshold, it is determined that the target device has a short-circuit fault.

10. The high-frequency switching power supply according to claim 6, characterized in that: Also includes: In response to a target device short circuit fault, the voltage is limited by a voltage loop controller.

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