Power supply system and control method thereof

Abstract

This case relates to a power supply system and its control method. Within a first preset time period, the system determines whether it is under heavy load based on multiple output voltages detected by the output capacitor. If all output voltages of the output capacitor are less than a first voltage threshold, the system is confirmed to be under heavy load. If at least one output voltage of the output capacitor is greater than or equal to the first voltage threshold, the system is determined to be under heavy load based on multiple output voltages detected by the output capacitor within a second preset time period. When the system is confirmed to be under heavy load, the power output of the DC / DC converter is terminated to achieve overload protection.

Description

Technical Field

[0001] This case relates to the field of power supply, and in particular to a power supply system and its control method. Background Technology

[0002] For LLC power supply systems utilizing open-loop control, to protect the LLC power supply system and related circuits, it is forbidden to start the system under load. Alternatively, during startup (i.e., before the voltage stabilizes), the load must be less than the preset values ​​of the switches and other connected circuits within the LLC power supply system. In other words, heavy-load startup is prohibited. To avoid heavy-load startup, LLC power supply systems often use guidance methods to instruct users on the correct operating procedures. However, this method lacks fault tolerance and can easily lead to damage to the LLC power supply system, such as system failure, in the event of misoperation.

[0003] Therefore, it is necessary to develop a power supply system and its control method to solve the problems faced by previous technologies. Summary of the Invention

[0004] The purpose of this invention is to provide a power supply system and its control method, which determines whether the power supply system is under heavy load based on multiple output voltages detected by the output capacitor, and controls the DC / DC converter to terminate energy output when under heavy load to achieve heavy load protection. Furthermore, the power supply system of this invention can be used for product testing without calibration, which can improve product delivery speed. In addition, the power supply system does not require pre-detection of the load through an additional power source, making the power supply system of this invention highly safe and cost-effective.

[0005] To achieve the above objectives, one embodiment of this invention provides a power supply system including a DC / DC converter, an output capacitor, a load, and a controller. The DC / DC converter includes an input terminal and an output terminal. The output capacitor is electrically connected to the output terminal of the DC / DC converter. The load is connected in parallel to the output capacitor. The controller is electrically connected to the DC / DC converter and the output capacitor, wherein the controller is configured to: within a first preset time period, determine whether the power supply system is in a heavy-load state based on multiple output voltages detected by the output capacitor. If all output voltages of the output capacitor are less than a first voltage threshold, then the power supply system is confirmed to be in a heavy-load state. If at least one output voltage of the output capacitor is greater than or equal to the first voltage threshold, then the power supply system is determined to be in a heavy-load state based on multiple output voltages detected by the output capacitor within a second preset time period. When the power supply system is confirmed to be in a heavy-load state, the power output of the DC / DC converter is terminated.

[0006] To achieve the above objectives, another embodiment of this invention provides a control method applied to a power supply system. The power supply system includes a DC / DC converter, an output capacitor, and a load. The output capacitor is electrically connected to the DC / DC converter, and the load is connected in parallel to the output capacitor. The control method includes the following steps: within a first preset time period, determining whether the power supply system is under heavy load based on multiple detected output voltages of the output capacitor; if all output voltages of the output capacitor are less than a first voltage threshold, then confirming that the power supply system is under heavy load; if at least one output voltage of the output capacitor is greater than or equal to the first voltage threshold, then determining whether the power supply system is under heavy load based on multiple detected output voltages of the output capacitor within a second preset time period. When it is confirmed that the power supply system is under heavy load, the energy output of the DC / DC converter is terminated. Attached Figure Description

[0007] Figure 1 This is the circuit architecture diagram of the power supply system in this case;

[0008] Figure 2 for Figure 1 The waveform of the output voltage across the output capacitor of the power supply system is shown.

[0009] Figure 3 for Figure 1 The diagram shows the relationship between the output voltage and capacitance of the output capacitor in a power supply system with a constant load; and...

[0010] Figure 4 for Figure 1 The flowchart of the control method for the power supply system is shown.

[0011] The reference numerals in the attached figures are explained as follows:

[0012] 1: Power System

[0013] Iin: Input current

[0014] Iout: Output current

[0015] 2: DC / DC converter

[0016] 21: Input end

[0017] 22: Output terminal

[0018] 23: Switch

[0019] 3: Output capacitor

[0020] Uo: Output voltage

[0021] 4: Load

[0022] 5: Controller

[0023] Vth1: First voltage threshold

[0024] Vth2: Second voltage threshold

[0025] S1-S8: Steps Detailed Implementation

[0026] Some typical embodiments that embody the features and advantages of this invention will be described in detail in the following description. It should be understood that this invention can have various variations in different forms, all of which do not depart from the scope of this invention, and the descriptions and drawings therein are for illustrative purposes only and not for limiting this invention.

[0027] The following detailed description of some embodiments of this case is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0028] Please see Figure 1 , Figure 2 and Figure 3 ,in Figure 1 This is the circuit architecture diagram of the power supply system in this case. Figure 2 for Figure 1 The waveform of the output voltage across the output capacitor of the power supply system is shown. Figure 3 for Figure 1 The diagram shows the relationship between the output voltage and capacitance of the output capacitor in a power supply system with a constant load. Figure 1 As shown, the power supply system 1 receives and converts the input current Iin into the output current Iout, and includes a DC / DC converter 2, an output capacitor 3, a load 4, and a controller 5.

[0029] In this embodiment, the DC / DC converter 2 can be an LLC power supply and includes an input terminal 21, an output terminal 22, and a switch 23. The DC / DC converter 2 receives and converts the input current Iin through the input terminal 21. The switch 23 can be, but is not limited to, a switching element in the secondary circuit of the DC / DC converter 2. The DC / DC converter 2 uses the operation of the switch 23 to control whether to output the output current Iout through the output terminal 22. When the switch 23 is turned on, the DC / DC converter 2 outputs the output current Iout through the output terminal 22. When the switch 23 is turned off, the DC / DC converter 2 stops outputting the output current Iout through the output terminal 22.

[0030] It should be noted that, Figure 1 The switch 23 in the diagram is only shown schematically for the convenience of understanding this case. Switch 23 can also be a switching element in a DC / DC converter, that is, there is no need to add an additional switch 23.

[0031] Output capacitor 3 is electrically connected to the output terminal 22 of DC / DC converter 2. When DC / DC converter 2 starts and switch 23 is turned on, i.e., when DC / DC converter 2 provides energy to the outside, DC / DC converter 2 charges output capacitor 3, causing the output voltage Uo on output capacitor 3 to gradually increase. When DC / DC converter 2 stops and switch 23 is turned off, i.e., when DC / DC converter 2 no longer provides energy to the outside, output capacitor 3 discharges to load 4, causing the output voltage Uo of output capacitor 3 to gradually decrease. Load 4 is connected in parallel to output capacitor 3. In this embodiment, when the output voltage Uo on output capacitor 3 reaches a preset first voltage threshold Vth1, the energy output of DC / DC converter 2 can be stopped, i.e., switch 23 is turned off to allow output capacitor 3 to discharge to load 4. The expression for the RC discharge channel formed by output capacitor 3 and load 4 is as follows.

[0032]

[0033] Where Uo is the output voltage across output capacitor 3, Vth1 is the first voltage threshold (the preset voltage threshold for output capacitor 3 to undergo discharge testing), t is the discharge time of output capacitor 3, τ is the time constant, R is the resistance of load 4, and C is the capacitance of output capacitor 3. Figure 3 As shown, when the load 4 is constant, the relationship between the capacitance value of different output capacitors 3 and their corresponding output voltage can be clearly seen. According to the above expression of the discharge channel, the discharge time of the output capacitor 3 is proportional to the resistance value of the load 4. In other words, the time it takes for the output voltage Uo on the output capacitor 3 to drop from the first voltage threshold Vth1 to the specified voltage is also related to the resistance value of the load 4.

[0034] Revisit Figure 1The controller 5 is electrically connected to the DC / DC converter 2 and the output capacitor 3. By continuously detecting the output voltage Uo of the output capacitor 3, it can determine whether the power supply system 1 is under heavy load. Specifically, within a first preset time period, that is, during the time when the DC / DC converter 2 charges the output capacitor 3, the controller 5 will detect the output voltage Uo of the output capacitor 3 multiple times. Based on the detected multiple output voltages Uo of the output capacitor 3, it can determine whether the power supply system 1 is under heavy load. It should be noted that the first preset time is a range value, which satisfies the following condition: 0 < T ≤ Tmax, where T is the first preset time, and Tmax is the maximum value that can be set according to actual needs, for example, Tmax = 1ms. Specifically, within the first preset time period, i.e., within the maximum value Tmax of the first preset time period, if all output voltages Uo detected by the controller 5 are less than the first voltage threshold Vth1, then the power supply system 1 is confirmed to be in a heavy load state. In this case, some faults often occur in the circuit, causing the output capacitor 3 to be unable to be charged to the set first voltage threshold Vth1 within the specified first preset time period. At this time, the current in the circuit is often large, and heavy load protection is required. Within the first preset time period, i.e., within the maximum value Tmax of the first preset time period, if at least one output voltage Uo detected by the controller 5 is greater than or equal to the first voltage threshold Vth1, then the first preset time is considered to end immediately, and the DC / DC converter 2 suspends energy output. In other words, at any moment within the maximum value Tmax of the first preset time period, as long as the controller 5 detects that the output voltage Uo of the output capacitor 3 is greater than or equal to the first voltage threshold Vth1, the first preset time is considered to end here, and the DC / DC converter 2 is controlled to suspend external energy output. In summary, there are two scenarios for the end of the first preset time: First, within time Tmax, all output voltages Uo of output capacitor 3 are less than the first voltage threshold Vth1, then the first preset time ends at Tmax; Second, at a certain moment within time Tmax, such as T0, the output voltage Uo of output capacitor 3 is detected to be greater than or equal to the first voltage threshold Vth1, then the first preset time ends at T0.

[0035] In the second scenario described above, due to the matching of power supply system 1 and load 4, or other reasons, after the DC / DC converter 2 suspends energy output, the output voltage Uo of output capacitor 3 may not immediately drop below the first voltage threshold Vth1. Therefore, controller 5 needs to continue monitoring the output voltage Uo of output capacitor 3 until it is less than or equal to the first voltage threshold Vth1. It should be noted that if the output voltage Uo of output capacitor 3 reaches the first voltage threshold Vth1 exactly at the maximum value Tmax of the first preset time, then after the DC / DC converter 2 suspends energy output, the output voltage Uo of output capacitor 3 will begin to decrease from the first voltage threshold Vth1. Figure 2 As shown (at this time, t1 is Tmax). Although the output voltage Uo of the output capacitor 3 charges to the first voltage threshold Vth1 within the specified first preset time, this does not necessarily mean that there are no other fault conditions in the power system 1 that could cause it to be under heavy load. The discharge characteristics of the output capacitor 3 still need to be detected for further judgment. In other words, after the DC / DC converter 2 suspends its external energy output, the controller 5 further determines whether the power system 1 is under heavy load based on the detection result of the output voltage Uo within a second preset time after the first preset time. That is, the second preset time is the discharge period of the output capacitor 3, and the starting point of the second preset time is the moment when the output voltage Uo of the output capacitor 3 first becomes less than or equal to the first voltage threshold Vth1. The second preset time is a fixed value that can be set according to actual needs. Specifically, the controller 5 determines whether the power system 1 is under heavy load based on multiple output voltages Uo of the output capacitor 3 detected within a second preset time period, a first voltage threshold Vth1, and a second voltage threshold Vth2. The second voltage threshold Vth2 is less than the first voltage threshold Vth1. The second voltage threshold Vth2 can be set according to actual needs (e.g., the charging and discharging characteristics of the capacitor). Within the second preset time period, when the controller 5 confirms that the power system 1 is under heavy load, it controls the DC / DC converter 2 to terminate energy output to achieve heavy load protection.

[0036] In one embodiment, such as Figure 2As shown, within a first preset time period, i.e., from time 0 to time t1, the controller 5 confirms that at least one of the output voltages Uo detected by the output capacitor 3 is equal to the first voltage threshold Vth1 (the output voltage Uo reaches the first voltage threshold Vth1 at time t1). Then, after the first preset time period ends, the controller controls the DC / DC converter 2 to pause energy output, causing the output voltage Uo to gradually decrease. The controller 5 then determines whether the power supply system 1 is in a heavy-load state based on the multiple output voltages Uo detected by the output capacitor 3 within a second preset time period. Further, within time t1 to time t2, the controller 5 acquires multiple output voltages Uo of the output capacitor 3 to determine whether the power supply system 1 is in a heavy-load state. If at least one of the output voltages Uo is greater than the first voltage threshold Vth1, then the power supply system 1 is confirmed to be in a heavy-load state, for example... Figure 2 Curve d in the figure; if it is confirmed that all output voltages Uo are less than the first voltage threshold Vth1 and greater than the second voltage threshold Vth2, for example, Figure 2 If curve c in the equation indicates that power system 1 is not under heavy load, then the following applies: If at least one of the output voltages Uo is less than the second voltage threshold, for example, ... Figure 2 If curves a and b are observed, it confirms that power system 1 is under heavy load.

[0037] After the second preset time has elapsed, if the controller 5 confirms that the power system 1 is not under heavy load, it controls the DC / DC converter 2 to continue outputting energy.

[0038] Please see Figure 4 , it is Figure 1The flowchart of the control method for the power supply system is shown. First, step S1 is executed, and within a first preset time period, it is determined whether the power supply system 1 is under heavy load based on the multiple output voltages Uo detected by the output capacitor 3. Next, step S2 is executed, and it is confirmed whether all output voltages Uo of the output capacitor 3 are less than the first voltage threshold Vth1. If the confirmation result of step S2 is yes, that is, it is confirmed that all output voltages Uo of the output capacitor 3 are less than the first voltage threshold Vth1, then step S5 is executed, confirming that the power supply system 1 is under heavy load. Next, step S6 is executed, and the energy output of the DC / DC converter 2 is terminated to achieve overload protection. If the confirmation result of step S2 is no, that is, it is confirmed that at least one output voltage Uo of the output capacitor 3 is greater than or equal to the first voltage threshold Vth1, then step S3 is executed, and it is determined whether the power supply system 1 is under heavy load based on the multiple output voltages Uo detected by the output capacitor 3 within a second preset time period. It should be noted that after the first preset time period ends, the DC / DC converter 2 has stopped energy output. Next, step S4 is executed, comparing multiple output voltages Uo of output capacitor 3 with a first voltage threshold Vth1 and a second voltage threshold Vth2, wherein the first voltage threshold Vth1 is greater than the second voltage threshold Vth2. If at least one output voltage Uo of the output capacitor is greater than the first voltage threshold Vth1 (step S41), then step S5 is executed to confirm that power system 1 is in a heavy-load state; if at least one output voltage Uo of output capacitor 3 is less than the second voltage threshold Vth2 (step S42), then step S5 is executed to confirm that power system 1 is in a heavy-load state; if all output voltages Uo of output capacitor 3 are less than the first voltage threshold Vth1 and greater than the second voltage threshold Vth2 (step S43), then step S7 is executed to confirm that power system 1 is not in a heavy-load state. Next, step S8 is executed, and after the second preset time has elapsed, the energy output of DC / DC converter 2 is restored. It should be noted that for steps S41 and S42, after confirming that power system 1 is in a heavy-load state, the DC / DC converter changes from pausing energy output to terminating energy output.

[0039] In summary, the power supply system and its control method in this case determine whether the power supply system is under heavy load based on multiple output voltages detected by the output capacitor, and control the DC / DC converter to terminate energy output when under heavy load to achieve heavy load protection. Furthermore, the power supply system in this case can be used for product testing without calibration, which can improve product delivery speed. In addition, the power supply system does not require additional power supply pre-testing, making the power supply system in this case both safe and cost-effective.

Claims

1. A power supply system, comprising: A DC / DC converter, comprising an input terminal and an output terminal; An output capacitor is electrically connected to the output terminal of the DC / DC converter; A load is connected in parallel to the output capacitor; and A controller, electrically connected to the DC / DC converter and the output capacitor, wherein the controller is configured to: Within a first preset time period, the system determines whether it is under heavy load based on the detected multiple output voltages of the output capacitor, wherein: If all the output voltages of the output capacitor are less than a first voltage threshold, then the power supply system is confirmed to be in the heavy load state. If at least one of the output voltages of the output capacitor is greater than or equal to the first voltage threshold, then the power supply system is determined to be in the heavy load state based on the multiple output voltages of the output capacitor detected within a second preset time period. as well as When the power system is confirmed to be in this heavy load state, the power output of the DC / DC converter is terminated.

2. The power supply system of claim 1, wherein the controller is further configured to: If, within the first preset time period, the output voltage of at least one of the output capacitors is greater than or equal to the first voltage threshold, then the DC / DC converter is controlled to pause energy output after the first preset time period ends.

3. The power supply system as described in claim 2, wherein, The controller is also configured as follows: During the second preset time period, based on the detected multiple output voltages of the output capacitor, the first voltage threshold, and a second voltage threshold, it is determined whether the power supply system is in the heavy load state, wherein the second voltage threshold is less than the first voltage threshold, wherein: If at least one of the output voltages is greater than the first voltage threshold, the power supply system is confirmed to be in the heavy load state. If all of the output voltages are less than the first voltage threshold and greater than a second voltage threshold, then it is confirmed that the power supply system is not in the heavy load state; and If at least one of the output voltages is less than the second voltage threshold, the power supply system is confirmed to be in the heavy load state.

4. The power supply system as described in claim 3, wherein, The controller is also configured as follows: If it is confirmed that the power system is not in the heavy load state, the DC / DC converter will continue to output energy after the second preset time ends.

5. A control method applied to a power supply system, wherein the power supply system includes a DC / DC converter, an output capacitor, and a load, the output capacitor being electrically connected to the DC / DC converter, and the load being connected in parallel to the output capacitor, wherein the control method includes: (a) Within a first preset time period, based on the detected multiple output voltages of the output capacitor, determine whether the power supply system is in a heavy load state, wherein: (a1) If all the output voltages of the output capacitor are less than a first voltage threshold, then the power supply system is confirmed to be in the heavy load state. as well as (a2) If at least one of the output voltages of the output capacitor is greater than or equal to the first voltage threshold, then the power supply system is determined to be in the heavy load state based on the multiple output voltages of the output capacitor detected within a second preset time period. as well as (b) When it is confirmed that the power system is in the heavy load state, terminate the power output of the DC / DC converter.

6. The control method as described in claim 5, wherein before step (a2), it further comprises: after the first preset time has elapsed, controlling the DC / DC converter to pause energy output.

7. The control method of claim 6, wherein step (a2) further comprises: During the second preset time period, based on the detected multiple output voltages of the output capacitor, the first voltage threshold, and a second voltage threshold, it is determined whether the power supply system is in the heavy load state, and the second voltage threshold is less than the first voltage threshold, wherein: If at least one of the output voltages is greater than the first voltage threshold, the power supply system is confirmed to be in the heavy load state. If all of the output voltages are less than the first voltage threshold and greater than a second voltage threshold, then it is confirmed that the power supply system is not in the heavy load state. as well as If at least one of the output voltages is less than the second voltage threshold, the power supply system is confirmed to be in the heavy load state.

8. The control method of claim 7, wherein step (a2) further comprises: If it is confirmed that the power system is not in the heavy load state, the DC / DC converter will continue to output energy after the second preset time ends.

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