Valley-gating method, device, controller, switching power supply system and medium

Abstract

A valley bottom selection method, device, controller, switching power supply system and medium. The method comprises: detecting the load size and input voltage size of the switching power supply system in the current switching period of the power switch tube; based on the detection result of the load size in the current switching period, generating a valley bottom identification signal matched with the load size in the current switching period; based on the detection result of the input voltage size in the current switching period, generating a valley bottom shielding signal; based on the valley bottom identification signal and the valley bottom shielding signal, generating a valley bottom selection signal to control the next switching period of the power switch tube to be turned on at the valley bottom selected by the valley bottom selection signal; wherein the valley bottom selected by the valley bottom selection signal is a valley bottom outside the valley bottom shielding range indicated by the valley bottom shielding signal. By using the above scheme, the switching frequency difference caused by the change of the input voltage can be reduced, and the consistency of the efficiency and load capacity of the switching power supply system can be improved.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, specifically to a valley selection method, device, controller, switching power supply system, and medium. Background Technology

[0002] Quasi-resonant mode is a control method for switching power supply systems. When a switching power supply operates in quasi-resonant mode, a valley-to-turn converter is usually installed inside the system. This converter controls the power switching transistor to turn on at the valley when its source-drain voltage reaches its minimum value, thereby significantly reducing the power supply system's losses.

[0003] Traditional valley-turn-on converters suffer from valley-level frequency hopping, causing significant changes in the switching frequency of the power transistors within a short period, resulting in audio noise. Therefore, traditional valley-turn-on converters are gradually being replaced by those with valley-locking functionality.

[0004] However, current switching power supply systems with valley-locked converters experience increased switching losses in the power transistors when the input voltage rises, leading to increased transistor temperatures and impacting system efficiency. Furthermore, the load-carrying capacity of the switching power supply system differs significantly between the input voltage increase and its initial capacity. Summary of the Invention

[0005] The problem this invention aims to solve is: how to improve the efficiency of switching power supply systems and improve the consistency of the load-carrying capacity of switching power supplies before and after changes in input voltage.

[0006] To address the above problems, this invention provides a valley selection method applied to a switching power supply system; the switching power supply system includes: a transformer and a power switching transistor connected to the transformer; the power switching transistor is used to determine whether the transformer supplies power to the load of the switching power supply system; the method includes:

[0007] The load and input voltage of the switching power supply system during the current switching cycle of the power switch are detected.

[0008] Based on the detection result of the load size in the current switching cycle, a valley identification signal matching the load size in the current switching cycle is generated; the valley identification signal is used to indicate the valley identification corresponding to the power switch tube when it is turned on in the next switching cycle under the load size in the current switching cycle.

[0009] Based on the detection result of the input voltage magnitude in the current switching cycle, a valley shielding signal is generated. The valley shielding signal is used to indicate the valley shielding range when the power switch is turned on in the next switching cycle.

[0010] Based on the valley bottom identification signal and the valley bottom shielding signal, a valley bottom selection signal is generated to control the power switch to conduct in the valley selected by the valley bottom selection signal in the next switching cycle;

[0011] The valley selected by the valley selection signal is the valley outside the valley shielding range indicated by the valley shielding signal.

[0012] Optionally, generating a valley shielding signal based on the detection result of the input voltage magnitude within the current switching cycle includes:

[0013] Determine the input voltage range within the current switching cycle;

[0014] Based on the determined input voltage range, the corresponding valley shielding range is determined;

[0015] The valley shielding signal is generated based on the determined valley shielding range.

[0016] Optionally, generating a valley shielding signal based on the detection result of the input voltage magnitude within the current switching cycle includes:

[0017] Determine whether the input voltage during the current switching cycle is greater than a preset voltage threshold;

[0018] When the input voltage is greater than a preset voltage threshold during the current switching cycle, valley shielding range indication information is received.

[0019] The valley shielding signal is generated based on the received valley shielding range indication information.

[0020] Optionally, generating a valley selection signal based on the valley bottom identification signal and the valley bottom shielding signal includes:

[0021] When the valley bottom indicator signal is located within the shielding range indicated by the valley bottom shielding signal, the Kth valley bottom after the shielding range indicated by the valley bottom shielding signal is taken as the valley bottom when the power switch is turned on in the next switching cycle; where K is a positive integer.

[0022] When the valley bottom indicator signal indicates that the valley bottom is outside the shielding range indicated by the valley bottom shielding signal, the valley bottom indicator signal indicates that the valley bottom is taken as the valley bottom when the power switch tube is turned on in the next switching cycle.

[0023] Optionally, K = 1.

[0024] This invention also provides a valley selection device applied to a switching power supply system; the switching power supply system includes: a transformer and a power switching transistor connected to the transformer; the power switching transistor is used to determine whether the transformer supplies power to the load of the switching power supply system; the device includes:

[0025] The load-corresponding valley generation unit is adapted to detect the load size of the switching power supply system during the current switching cycle of the power switch transistor, and generate a valley identification signal that matches the load size during the current switching cycle based on the detection result of the load size during the current switching cycle; the valley identification signal is used to indicate the valley identification corresponding to the power switch transistor when it is turned on in the next switching cycle under the load size during the current switching cycle.

[0026] Valley shielding unit is adapted to detect the input voltage of the power switch system during the current switching cycle of the power switch transistor, and generate a valley shielding signal based on the detection result of the input voltage during the current switching cycle. The valley shielding signal is used to indicate the valley shielding range when the power switch transistor is turned on in the next switching cycle.

[0027] Valley selection unit is adapted to generate a valley selection signal based on the valley identification signal and the valley shielding signal, so as to control the power switch to conduct in the valley selected by the valley selection signal in the next switching cycle;

[0028] The valley selected by the valley selection signal is the valley outside the valley shielding range indicated by the valley shielding signal.

[0029] Optionally, the load-corresponding valley generation unit includes:

[0030] A bidirectional encoding circuit, with its input terminal connected to the voltage feedback port of the switching power supply system, is adapted to detect the load magnitude of the switching power supply system during the current switching cycle of the power switch transistor and generate a corresponding pulse encoding sequence.

[0031] The load-corresponding valley logic generation circuit is connected to the bidirectional encoding circuit. It is adapted to determine the load size in the current switching cycle based on the detection result of the load size in the current switching cycle, select the valley corresponding to the power switch when it is turned on in the next switching cycle based on the load size, and generate a valley identification signal that represents the selected valley position.

[0032] Optionally, the valley floor shielding unit includes:

[0033] The first input voltage comparison circuit is adapted to be connected to the input voltage sampling port of the switching power supply system and to determine the input voltage range in the current switching cycle.

[0034] The first valley shielding range determination circuit is suitable for determining the corresponding valley shielding range based on the determined input voltage range and generating the corresponding valley shielding signal.

[0035] Optionally, the first input voltage comparison circuit includes: a first comparison sub-circuit, N-2 second comparison sub-circuits, and N-2 NOR gates, where N is the number of input voltage ranges;

[0036] The first comparison sub-circuit includes a first comparator, and each of the N-2 second comparison sub-circuits includes a second comparator and an NOT gate connected to the second comparator.

[0037] The first input terminal of the first comparator and each of the second comparators are connected to the input voltage sampling port of the switching power supply system, and the second input terminal is connected to each reference voltage output terminal.

[0038] The first comparator circuit and the first second comparator circuit, as well as adjacent second comparator circuits, are connected by NOR gates.

[0039] Optionally, the first comparator sub-circuit further includes a first buffer connected to the first comparator, and the second comparator sub-circuit at the end further includes a second buffer connected to a NAND gate.

[0040] Optionally, the valley floor shielding unit further includes:

[0041] The first input voltage detection circuit has its input terminal connected to the input voltage sampling port of the switching power supply system and its output terminal connected to the first input voltage comparison circuit. It is adapted to detect the input voltage of the switching power supply system based on the input information of the input voltage sampling port of the switching power supply system.

[0042] Optionally, the valley floor shielding unit includes:

[0043] The second input voltage comparison circuit is adapted to determine whether the input voltage in the current switching cycle is greater than a preset voltage threshold.

[0044] The receiving circuit is adapted to receive valley shielding range indication information when the input voltage is greater than a preset voltage threshold during the current switching cycle;

[0045] The second valley shielding range determination circuit is adapted to generate the valley shielding signal based on the received valley shielding range indication information.

[0046] Optionally, the receiving circuit includes:

[0047] The power-on configuration sub-circuit is connected to the valley shielding range indicator port of the switching power supply system. It is adapted to select the valley shielding range of the power switching transistor in high-voltage mode and generate the corresponding valley shielding signal through the input information of the valley shielding range indicator port.

[0048] Optionally, the valley shielding unit further includes: a second input voltage detection circuit, with its input terminal connected to the input voltage sampling port of the switching power supply system and its output terminal connected to the second input voltage comparison circuit, adapted to detect the input voltage of the switching power supply system based on the input information of the input voltage sampling port of the switching power supply system.

[0049] Optionally, the valley selection unit is adapted to, when the valley identifier indicated by the valley identifier signal is within the shielding range indicated by the valley shielding signal, to take the Kth valley after the shielding range indicated by the valley shielding signal as the valley when the power switch is turned on in the next switching cycle; and when the valley identifier indicated by the valley identifier signal is outside the shielding range indicated by the valley shielding signal, to take the valley identifier indicated by the valley identifier signal as the valley when the power switch is turned on in the next switching cycle; wherein, K is a positive integer.

[0050] Optionally, the valley bottom gate device further includes:

[0051] Valley bottom update unit, connected to valley bottom selection unit, is adapted to update the valley bottom selected when the power switch is turned on in the next switching cycle based on the valley bottom selection signal.

[0052] This invention also provides a switching power supply controller, including any of the valley selection devices described above.

[0053] This invention also provides a switching power supply system, which includes the switching power supply controller described above.

[0054] The present invention also provides a computer-readable storage medium having a computer program stored thereon, the computer program being executed by a processor to implement the steps of any of the methods described above.

[0055] Compared with the prior art, the technical solution of the embodiments of the present invention has the following advantages:

[0056] The present invention utilizes the method of detecting the load size and input voltage of the power switch in the current switching cycle of the power switch system. Based on the detected load size, a valley identification signal matching the load size of the current switching cycle is generated. Based on the detected input voltage, a valley number shielding signal is generated. Finally, based on the valley identification signal and the valley shielding signal, a valley selection signal is generated. This controls the power switch to conduct in the valley selected by the valley selection signal in the next switching cycle. Since the valley selected by the valley selection signal is outside the valley shielding range indicated by the valley number shielding signal, the impact of increased input voltage on the switching losses of the power switch can be reduced, thereby improving the efficiency of the power supply system. Simultaneously, since the valley selected by the valley selection signal is outside the valley shielding range indicated by the valley number shielding signal, the difference in switching frequency caused by input voltage changes can be reduced, improving the consistency of the power supply system's load-carrying capacity. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the circuit structure of a switching power supply;

[0058] Figure 2 This is a flowchart of a valley bottom selection method in an embodiment of the present invention;

[0059] Figure 3 This is a schematic diagram of the structure of a valley bottom selection device in an embodiment of the present invention;

[0060] Figure 4 This is a schematic diagram of the number of valley shields under different input voltages in an embodiment of the present invention;

[0061] Figure 5 yes Figure 3 A timing diagram of the signals during the operation of the Zhonggudi gating device;

[0062] Figure 6 This is a schematic diagram of another valley bottom selection device in an embodiment of the present invention. Detailed Implementation

[0063] Figure 1 This is a schematic diagram of the circuit structure of a switching power supply system. (Refer to...) Figure 1 When power switch M1 is turned on, the AC voltage source AC charges the primary winding Np of the transformer, and the freewheeling diode D1, which is connected in series with the secondary winding Ns, is disconnected and does not supply power to the load. When power switch M1 is turned off, the primary winding Np begins to demagnetize, the freewheeling diode D1 turns on, and the secondary winding Ns supplies power to the load. After the primary winding Np has finished demagnetizing, it enters a free resonance state.

[0064] The output voltage Vout of the switching power supply system is connected to the voltage feedback port FB of the switching power supply controller 20 via the error amplification and isolation module 11. Thus, the switching power supply controller 20 can obtain the output voltage Vout of the switching power supply system through the voltage feedback port FB.

[0065] In addition to the voltage feedback port FB, the switching power supply controller 20 also has a primary-side current detection port CS, a gate drive port GATE, a demagnetizing port DMG, a supply voltage input port VDD, an input voltage sampling port VIN, and a ground port GND. The primary-side current detection port CS is used to detect the magnitude of the current when the power switch M1 is turned on. The gate drive port GATE is used to drive the power switch M1. The demagnetizing port DMG indirectly samples the output voltage through an external resistor, enabling functions such as trough detection, output overvoltage and undervoltage protection. The supply voltage input port VDD supplies power to the switching power supply controller 20. The input voltage sampling port VIN samples the input voltage provided by the AC voltage source AC. The ground port GND is the ground terminal of the switching power supply controller 20.

[0066] In practical applications, the switching power supply controller 20 can be equipped with a valley-to-conduction converter. This valley-to-conduction converter is connected to the demagnetizing port DMG and can receive the auxiliary winding voltage sampled by the demagnetizing port DMG. It then generates a resonant valley pulse signal of the resonant voltage waveform at the drain terminal of the power switch M1. Based on the resonant valley pulse signal, the feedback voltage input at the voltage feedback port FB, and the gate drive signal at the gate drive port GATE, the controller selects the valley to be turned on and locks the selected valley.

[0067] Since the valley-conduction converter controls the power switch M1 to be turned on only at the valley position, the operating frequency of the power switch M1 can be expressed as: 1 / (T ON +T OFF +(n-0.5)·T valley Where n represents the valley floor position, T ON and T OFF These represent the on-time and off-time of power switch M1 within one switching cycle, respectively, T. valley It is the resonant period of the inductance and parasitic capacitance. When the system parameters are fixed, T valley The time remains unchanged, T ON and T OFF The time T varies significantly depending on the input voltage. As the input voltage increases, T... ON With T OFFReducing the input voltage increases the operating frequency of the power switch M1, leading to increased switching losses and ultimately higher temperatures in M1, thus impacting the efficiency of the switching power supply system. Furthermore, the load-carrying capacity of the switching power supply system differs significantly before and after the input voltage increase.

[0068] To address this problem, this invention provides a valley selection method. This method detects the load and input voltage of the power switch in the current switching cycle of the power transistor. Based on the detected load, a valley identification signal matching the load size of the current switching cycle is generated. Based on the detected input voltage, a valley number shielding signal is generated. Finally, a valley selection signal is generated based on the valley identification and shielding signals. This controls the power switch to conduct in the valley selected by the valley selection signal in the next switching cycle. Since the valley selected by the valley selection signal is outside the valley shielding range indicated by the valley number shielding signal, the impact of increased input voltage on the switching losses of the power switch can be reduced, thereby improving the efficiency of the power supply system. Simultaneously, it improves the consistency of the power supply's load-carrying capacity before and after input voltage changes.

[0069] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0070] Reference Figure 2 This invention provides a valley bottom selection method.

[0071] The method is applied to a switching power supply system. The switching power supply system can be referred to... Figure 1 The structure is shown in the diagram. The switching power supply system includes: a transformer and a power switch connected to the transformer; the power switch is used to determine whether the transformer supplies power to the load of the switching power supply system. Using the valley selection method, the valley of power switch conduction in the next switching cycle can be determined based on the load and input voltage conditions of the switching power supply system in the current switching cycle.

[0072] Specifically, the method may include the following steps:

[0073] Step 11: Detect the load size and input voltage size of the switching power supply system during the current switching cycle of the power switch transistor.

[0074] In practice, by detecting the load size of the switching power supply system during the current switching cycle, the load change of the switching power supply system during the current switching cycle can be known, which is beneficial for generating a matching valley identification signal based on the load size in the future.

[0075] In practical implementation, by detecting the input voltage of the switching power supply system during the current switching cycle, the changes in the input voltage of the switching power supply system during the current switching cycle can be known. This allows the power switching transistor to be kept in the off state and not turned on when it is greatly affected by the input voltage changes, thereby reducing the increase in switching losses of the power switching transistor caused by the input voltage changes.

[0076] Step 12: Based on the detection result of the load size in the current switching cycle, generate a valley identification signal that matches the load size in the current switching cycle.

[0077] The valley identification signal is used to indicate the valley identification corresponding to the power switch tube when it is turned on in the next switching cycle, under the load size in the current switching cycle.

[0078] In practice, the valley identification signal is determined solely based on the load conditions of the switching power supply system to identify the conduction valley. At this point, the impact of input voltage changes on the power switching transistors is not considered.

[0079] Step 13: Based on the detection results of the input voltage magnitude within the current switching cycle, generate a valley shielding signal.

[0080] The valley number shielding signal is used to indicate the valley shielding range of the power switch when it is turned on in the next switching cycle.

[0081] In practice, based on the detection results of the input voltage magnitude within the current switching cycle, various methods can be used to generate valley-bottom shielding signals, and no restrictions are imposed here.

[0082] In one embodiment of the present invention, the number of valleys that are matched to the changes in the input voltage during the current switching cycle can be determined based on the changes in the input voltage. This makes the final valley shielding range as accurate as possible and minimizes the switching losses of the power switch.

[0083] Specifically, generating a valley shielding signal based on the detection result of the input voltage magnitude within the current switching cycle may include: determining the input voltage range within the current switching cycle; determining the corresponding valley shielding range based on the determined input voltage range; and generating the valley shielding signal based on the determined valley shielding range.

[0084] In specific implementation, different input voltage ranges can be preset, and valley shielding ranges can be set for each input voltage range. By judging the input voltage range in the current switching cycle, it can be determined which input voltage range the input voltage is in the current switching cycle. Then, based on the determined input voltage range, the corresponding valley shielding range can be determined, and the valley shielding signal can be generated based on the determined valley shielding range.

[0085] In another embodiment of the invention, regardless of the specific changes in the input voltage during the current switching cycle, as long as the input voltage is high, a fixed number of valleys is shielded; that is, the valley shielding range does not change with the input voltage. Subsequently, during electromagnetic compatibility (EMC) testing, at the test load point, whether switching from light load to heavy load or from heavy load to light load, by setting the number of shielded valleys, the power switch can always be turned on at the same valley position at that load point, optimizing the consistency of EMC test results.

[0086] Specifically, generating a valley shielding signal based on the detection result of the input voltage magnitude within the current switching cycle includes: determining whether the input voltage within the current switching cycle is greater than a preset voltage threshold; when the input voltage within the current switching cycle is greater than the preset voltage threshold, receiving valley shielding range indication information; and generating the valley shielding signal based on the received valley shielding range indication information.

[0087] In practice, the preset voltage threshold can be set according to the actual situation. When the input voltage is greater than the preset voltage threshold, it indicates that the switching loss of the power switch will increase significantly due to the increase in input voltage.

[0088] When the input voltage is greater than the preset voltage threshold during the current switching cycle, the valley shielding range indication information can be received directly. This valley shielding range indication information can indicate the valley shielding range without determining the input voltage range, and the valley shielding signal can be generated directly based on the indicated valley shielding range.

[0089] In practical implementation, the valley shielding signal can indicate the valley shielding range in various ways. For example, a switching cycle may include N valleys, where N is an integer. The valley shielding signal can carry an H value, where H represents the first H valleys that can be indicated from the N valleys, and H is an integer. Alternatively, the valley shielding signal can carry an upper limit H1 and a lower limit H2 of the valley shielding range. In this case, the valley shielding range is from the H1th valley to the H2th valley among the N valleys.

[0090] Step 14: Based on the valley bottom identification signal and the valley bottom shielding signal, generate a valley bottom selection signal to control the power switch to conduct in the valley selected by the valley bottom selection signal in the next switching cycle.

[0091] The valley selected by the valley selection signal is the valley outside the valley shielding range indicated by the valley shielding signal.

[0092] In another embodiment of the present invention, when the valley bottom indicator indicated by the valley bottom indicator signal is located within the shielding range indicated by the valley bottom shielding signal, the Kth valley bottom after the shielding range indicated by the valley bottom shielding signal is taken as the valley bottom when the power switch tube is turned on in the next switching cycle, where K is a positive integer.

[0093] In another embodiment of the present invention, when the valley bottom indicator signal indicates that the valley bottom indicator is outside the shielding range indicated by the valley bottom shielding signal, the valley bottom indicator signal indicates that the valley bottom indicator is taken as the valley bottom when the power switch tube is turned on in the next switching cycle.

[0094] For example, when the valley shielding signal indicates the valley shielding range of the first H valleys of N valleys, and the valley marking signal indicates the valley marking of the second valley.

[0095] If H is greater than 2, then the Kth valley after the first H valleys out of the N valleys can be taken as the valley when the power switch turns on in the next switching cycle. For example, when K = 1, the Kth valley after the first H valleys is the (H+1)th valley.

[0096] In other embodiments, K can also be other values. K can be preset or indicated by a valley selection signal.

[0097] If H is less than 2, then the second valley among the N valleys can be taken as the valley when the power switch turns on in the next switching cycle.

[0098] As described above, the valley selection method in this embodiment of the invention, while achieving valley locking, can reduce the switching frequency of the power switch when the input voltage changes by detecting the input voltage and load. This keeps the switching frequency of the power switch within a certain range, reducing the frequency difference caused by input voltage changes, preventing the power switch temperature from rising, improving the efficiency of the switching power supply system, and enhancing the consistency of load-carrying capacity under different input voltages. Valley selection through valley shielding can optimize the EMC margin of the switching power supply system at higher input voltages, thereby simplifying the EMC design of the system and reducing its size.

[0099] In addition, by receiving valley shielding range indication information, the system can be activated at a fixed valley location regardless of load switching at the load point of the EMC test, thereby improving the consistency of EMC test results.

[0100] To enable those skilled in the art to better understand and implement the present invention, the user terminal and computer-readable storage medium corresponding to the above method are described in detail below.

[0101] This invention provides a valley selection device applied to a switching power supply system. The switching power supply system includes a transformer and a power switching transistor connected to the transformer. The power switching transistor is used to determine whether the transformer supplies power to the load of the switching power supply system.

[0102] Specifically, the valley bottom selection device includes: a load-corresponding valley bottom generation unit, a valley bottom shielding unit, and a valley bottom selection unit. Wherein:

[0103] The load-corresponding valley generation unit is adapted to detect the load size of the switching power supply system in the current switching cycle of the power switch tube, and generate a valley identification signal that matches the load size in the current switching cycle based on the detection result of the load size in the current switching cycle; the valley identification signal is used to indicate the valley identification corresponding to the power switch tube when it is turned on in the next switching cycle under the load size in the current switching cycle.

[0104] The valley shielding unit is adapted to detect the input voltage of the power switch system during the current switching cycle of the power switch transistor, and generate a valley shielding signal based on the detection result of the input voltage during the current switching cycle. The valley shielding signal is used to indicate the valley shielding range when the power switch transistor is turned on in the next switching cycle.

[0105] The valley selection unit is adapted to generate a valley selection signal based on the valley identification signal and the valley shielding signal, so as to control the power switch to conduct in the valley selected by the valley selection signal in the next switching cycle.

[0106] The valley selected by the valley selection signal is the valley outside the valley shielding range indicated by the valley shielding signal.

[0107] Figure 3 This is a schematic diagram of the valley bottom selection device according to one embodiment of the present invention. (Refer to...) Figure 3 The valley bottom selection device may include: a load-corresponding valley bottom generation unit 21, a valley bottom shielding unit 22, and a valley bottom selection unit 23.

[0108] In one embodiment of the present invention, the load-corresponding valley generation unit 21 may include: a bidirectional encoding circuit 211 and a load-corresponding valley logic generation circuit 212. Wherein:

[0109] The bidirectional encoding circuit 211 has its input terminal connected to the voltage feedback port FB of the switching power supply system, and is adapted to detect the load size of the switching power supply system during the current switching cycle of the power switch tube, and generate the corresponding pulse code sequence.

[0110] The load-corresponding valley logic generation circuit 212 is connected to the bidirectional encoding circuit 221. It is adapted to determine the load size in the current switching cycle based on the detection result of the load size in the current switching cycle, select the valley corresponding to the power switch when it is turned on in the next switching cycle based on the load size, and generate a valley identification signal representing the selected valley position.

[0111] In a specific implementation, the bidirectional encoding circuit 211 can detect the voltage at the voltage feedback port FB and generate a pulse code sequence Q[m:0] based on the detected feedback voltage. Specifically, the bidirectional encoding circuit 211 can perform addition or subtraction operations based on changes in the feedback voltage to generate the corresponding pulse code sequence Q[m:0]. The feedback voltage reflects the load size of the switching power supply system during the current switching cycle of the power switch transistor; therefore, the pulse code sequence Q[m:0] generated based on the feedback voltage can also reflect the load size during the current switching cycle of the power switch transistor. The pulse code sequence Q[m:0] consists of m bits, namely Q0, Q1, ..., Qm. Different feedback voltages result in different pulse code sequences Q[m:0].

[0112] In a specific implementation, the pulse-coded sequence Q[m:0] generated by the bidirectional encoding circuit 211 is output to the load-corresponding valley logic generation circuit 212 for logical operation, and outputs a valley identification signal that matches the load size. For example, the valley identification signal can indicate that, given the load size in the current switching cycle, the power switch should be turned on at the 5th valley in the next switching cycle. That is, considering only the load size, the power switch should be turned on at the 5th valley in the next switching cycle.

[0113] In one embodiment of the present invention, reference is made to... Figure 3 The valley bottom shielding unit 22 may include: a first input voltage comparison circuit 221 and a first valley bottom shielding range determination circuit 222. Wherein:

[0114] The first input voltage comparison circuit 221 is adapted to be connected to the input voltage sampling port VIN of the switching power supply system, and to determine the input voltage range in which the input voltage is located during the current switching cycle;

[0115] The first valley shielding range determination circuit 222 is adapted to determine the corresponding valley shielding range based on the determined input voltage range and generate the corresponding valley shielding signal.

[0116] At this time, the valley shielding unit 22 can shield the number of valleys that are adapted to the changes in the input voltage during the current switching cycle, thereby making the final valley shielding range as accurate as possible and minimizing the switching losses of the power switch.

[0117] In a specific implementation, the first input voltage comparison circuit 221 may include: a first comparison sub-circuit, N-2 second comparison sub-circuits and N-2 NOR gates, where N is the number of input voltage ranges;

[0118] The first comparator sub-circuit includes a first comparator CMP1, and the N-2 second comparator sub-circuits each include a second comparator and an NOT gate connected to the second comparator.

[0119] For example, the first second comparator circuit connected to the first comparator circuit may include a second comparator CMP2 and an NOT gate F1, the second second comparator circuit connected to the first comparator circuit may include a second comparator CMP3 and an NOT gate F2, ..., and the last second comparator circuit connected to the first comparator circuit may include a second comparator CMPn and an NOT gate F(n-1).

[0120] The first input terminals of the first comparator CMP1 and each of the second comparators CMP2 to CMPn are connected to the input voltage sampling port of the switching power supply system, and the second input terminals are connected to the output terminals of each reference voltage. For example, the second input terminal of the first comparator CMP1 and the first reference voltage output terminal are adapted to be connected to the first reference voltage V. TH1 The second input terminal and the second reference voltage output terminal of the second comparator CMP2 are adapted to be connected to the first reference voltage V. TH2 The second input terminal of the second comparator CMPn and the output terminal of the nth reference voltage are adapted to be connected to the first reference voltage V. THn Each reference voltage is different and is used to divide the input voltage range.

[0121] The first comparator circuit and the first second comparator circuit, as well as adjacent second comparator circuits, are connected by NOR gates. For example, the first comparator circuit and the first second comparator circuit are connected by NOR gate X1, and the first second comparator circuit and the second second comparator circuit are connected by NOR gate X2.

[0122] In one embodiment of the present invention, the first comparator sub-circuit further includes a first buffer K1 connected to the first comparator CMP1, and the second comparator sub-circuit at the end further includes a second buffer K2 connected to a NAND gate F(n-1). The first buffer K1 and the second buffer K2 can buffer the output of the corresponding comparator.

[0123] The input voltage of the switching power supply system is compared with the corresponding reference voltage by each comparator circuit to obtain the discrimination code sequence VL[n:1]. VL[n:1] contains n bits, namely VL1 to VLn. Among the bits VL1 to VLn, at most one is high level, and the others are low level. The input voltage of the switching power supply system is located within the voltage range corresponding to the high level bit. If all bits VL1 to VLn are low level, the input voltage is in the lowest voltage range.

[0124] It should be noted that in other embodiments, the first buffer K1 and the second buffer K2 may not be provided.

[0125] In practice, different input voltage ranges can be preset, and valley shielding ranges can be set for each input voltage range. Figure 4 This diagram illustrates a curve showing the number of valley shielding values ​​under different input voltages. As the input voltage increases, the number of valley shielding values ​​gradually increases. This effectively addresses the problem of a significant increase in switching frequency caused by rising input voltage, effectively reducing switching losses under high voltage and improving the consistency of load-carrying capacity under both high and low voltage conditions. For example, when the input voltage of the switching power supply system is in the range of V1 to V2, the first valley can be shielded. When the input voltage of the switching power supply system is in the range of V2 to V3, the first two valleys can be shielded. Here, V1 < V2 < V3.

[0126] After obtaining the discrimination coding sequence VL[n:1], the first valley shielding range determination circuit 222 can determine the corresponding input voltage range based on the discrimination coding sequence VL[n:1], and then determine the corresponding valley shielding range based on the determined input voltage range, thereby generating the valley shielding signal based on the determined valley shielding range.

[0127] In a specific implementation, the valley shielding signal is used to indicate the valley shielding range when the power switch is turned on in the next switching cycle. For example, the valley shielding signal can carry an H value, where H represents the first H valleys that can be shielded by indicating N valleys.

[0128] In one embodiment of the present invention, the valley shielding unit 22 may further include a first input voltage detection circuit 223. The first input voltage detection circuit 223 has its input terminal connected to the input voltage sampling port VIN of the switching power supply system, and its output terminal connected to the first input voltage comparison circuit 221. It is adapted to detect the input voltage of the switching power supply system based on the input information of the input voltage sampling port VIN of the switching power supply system.

[0129] In practical applications, the input voltage of a switching power supply system may be very high, making it impossible to directly input the input voltage of the switching power supply system to the first input voltage comparison circuit 221 for comparison. Therefore, a first input voltage detection circuit 223 can be set up to proportionally reduce the input voltage of the switching power supply system through voltage conversion and sample it to the first input voltage comparison circuit 221 for comparison.

[0130] In a specific implementation, the valley selection unit 23 can receive the valley identification signal and the valley shielding signal, thereby generating a valley selection signal. The valley selection signal is used to indicate which valley the power switch will conduct in the next switching cycle.

[0131] In specific implementation, the valley selection unit 23 can, when the valley identifier indicated by the valley identifier signal is within the shielding range indicated by the valley shielding signal, select the Kth valley after the shielding range indicated by the valley shielding signal as the valley when the power switch is turned on in the next switching cycle. Conversely, when the valley identifier indicated by the valley identifier signal is outside the shielding range indicated by the valley shielding signal, select the valley identifier indicated by the valley identifier signal as the valley when the power switch is turned on in the next switching cycle, where K is a positive integer.

[0132] For example, when a switching power supply system operates at high voltage, the valley shielding signal can indicate the first H valleys out of N valleys. Assuming the valley identifier signal indicates the 2nd valley, if H is greater than 2, the Kth valley after the first H valleys out of the N valleys can be taken as the valley when the power switch is turned on in the next switching cycle. If H is less than 2, the 2nd valley out of the N valleys can be taken as the valley when the power switch is turned on in the next switching cycle.

[0133] Under low voltage conditions, the valley shielding signal will not indicate the valley shielding range. At this time, the opening valley position of the power switch is determined by the valley marking signal corresponding to the full output load.

[0134] In practice, the value of K can be 1 or other values; there are no restrictions here.

[0135] Figure 5 for Figure 3 A timing diagram illustrating the signals during the operation of the Zhonggudi gating device. (Refer to...) Figure 5 Taking a switching cycle that includes 3 valleys as an example, during the period from 0 to t1, the voltage of the voltage feedback port FB of the switching power supply remains unchanged and the input voltage is low. At this time, the valley shielding signal indicates that the valley shielding range is 000, that is, the first 0 valleys are shielded. Then the valley selection unit outputs the first valley selection signal, that is, the first valley is selected to turn on the power switching transistor.

[0136] During the period from t1 to t2, the input voltage gradually rises to become high voltage. At this time, the voltage of the voltage feedback port FB of the switching power supply remains unchanged. The valley shielding signal indicates that the valley shielding range is 001, that is, the first valley is shielded. Then the valley selection unit outputs the second valley selection signal, that is, the second valley is selected to turn on the power switching transistor.

[0137] During the period from t2 to t3, the input voltage continues to rise. At this time, the voltage of the voltage feedback port FB of the switching power supply remains unchanged. The valley shielding signal indicates that the valley shielding range is 010, that is, the first two valleys are shielded. Then the valley selection unit outputs the third valley selection signal, that is, the third valley is selected to turn on the power switching transistor.

[0138] This shows that during the period from 0 to t3, the valley shielding signal is effective, and the valley selection signal gradually switches to the second and third valleys.

[0139] During the period from t3 to t4, the input voltage remains constant and at a low value. The valley shielding signal indicates that the valley shielding range is 000, and the valley selection signal is completely determined by the load.

[0140] At time t4, the input voltage increases instantaneously, the valley shielding signal is effective, and the indicated valley shielding range is 010. The first two valleys are shielded, and the valley selection signal is switched from the first valley selection signal to the third valley selection signal. The power switch is turned on at the third valley.

[0141] Figure 6 This is a schematic diagram of another valley bottom selection device in an embodiment of the present invention. Figure 3 Unlike the valley bottom gate device, in Figure 6 In the illustrated embodiment, the valley shielding unit 22 may include: a second input voltage comparison circuit 321, a receiving circuit 322, and a second valley shielding range determination circuit 323. Wherein:

[0142] The second input voltage comparison circuit 321 is adapted to determine whether the input voltage during the current switching cycle is greater than a preset voltage threshold V. TH ;

[0143] The receiving circuit 322 is adapted to operate when the input voltage is greater than a preset voltage threshold V during the current switching cycle. TH At that time, receive valley floor shielding range indication information;

[0144] The second valley shielding range determination circuit 323 is adapted to generate the valley shielding signal based on the received valley shielding range indication information.

[0145] In a specific implementation, the second input voltage comparison circuit 321 can be directly connected to the input voltage sampling port of the switching power supply system, thereby detecting the input voltage of the switching power supply system and comparing it with a preset voltage threshold V. TH A comparison is made when the input voltage of the switching power supply system is greater than the preset voltage threshold V. TH This indicates that the switching power supply system is operating under high voltage. When the input voltage of the switching power supply system is less than or equal to the preset voltage threshold V... TH This indicates that the switching power supply system is operating under low voltage conditions.

[0146] In practical implementation, users can input valley shielding range indication information to indicate the number of valleys that should be shielded when the switching power supply system is operating in high-voltage and low-voltage states. Specifically, when the switching power supply system is operating in low-voltage state, the number of valleys that should be shielded is 0, and the second valley shielding range determination circuit 323 can determine the valleys where the power switch transistors are turned on solely based on the valley identification signal. When the switching power supply system is operating in high-voltage state, the number of valleys that should be shielded can be set based on practical experience.

[0147] For example, the valley shielding signal is used to indicate the valley shielding range when the power switch is turned on in the next switching cycle. For instance, the valley shielding signal indicates the first H valleys of the N valleys to be shielded. If the valley indicated by the valley indicator signal is not located within the first H valleys, then the valley indicated by the valley indicator signal can be taken as the final open valley. If the valley indicated by the valley indicator signal is located within the first H valleys, then the Kth valley after the valley indicated by the valley indicator signal can be taken as the final open valley. For example, when K=1, the 1st valley after the valley indicated by the valley indicator signal is taken as the final open valley.

[0148] In one embodiment of the present invention, the receiving circuit 322 may include a power-on configuration sub-circuit 3221. The power-on configuration sub-circuit 3221 is connected to the valley shielding range indication port PinX of the switching power supply system, and is adapted to select the valley shielding range of the power switching transistor in high-voltage mode and generate a corresponding valley shielding signal through the input information of the valley shielding range indication port PinX.

[0149] In practical implementation, the valley shielding range indicator port PinX is a newly added port on the switching power supply controller, specifically designed for connecting to the valley shielding range. Therefore, under high voltage conditions, a fixed number of points can always be shielded, ensuring that regardless of load switching, the circuit remains in the same valley position at a given load point, facilitating consistent test results during subsequent electromagnetic compatibility (EMC) testing.

[0150] In one embodiment of the present invention, the valley shielding unit 22 may further include a second input voltage detection circuit 324. The input terminal of the second input voltage detection circuit 324 is connected to the input voltage sampling port VIN of the switching power supply system, and the output terminal is connected to the second input voltage comparison circuit 321, adapted to detect the input voltage of the switching power supply system based on the input information of the input voltage sampling port of the switching power supply system.

[0151] Similar to the function of the first input voltage detection circuit, when the input voltage of the switching power supply system may be very large, the second input voltage detection circuit 324 can reduce the input voltage of the switching power supply system proportionally through voltage conversion and sample it to the second input voltage comparison circuit 321 for comparison.

[0152] In a specific implementation, the valley selection unit 23 can receive the valley identification signal and the valley shielding signal to generate a valley selection signal. For example, when there are N valleys in a switching cycle, the valley selection signal can select any valley from the 1st to the Nth valley as the conduction valley of the power switch.

[0153] In one embodiment of the present invention, reference is made to... Figure 3 and Figure 6 The valley selection device may further include a valley update unit 24. The valley update unit 24 may be connected to the valley selection unit 23 and is adapted to update the valley selected when the power switch is turned on in the next switching cycle based on the valley selection signal.

[0154] In a specific implementation, the valley update unit 24 includes N flip-flops, designated DFF_1 to DFF_N. When a flip-flop detects a falling edge of the voltage at the gate drive port GATE, it updates the valley signal selected for the current cycle. Only one flip-flop outputs a high level at any given time. Therefore, the valley state can be updated when the falling edge of the gate drive port GATE arrives, and the power switch can be controlled to turn on according to the updated valley state in the next switching cycle.

[0155] As described above, the valley selection device in this embodiment of the invention, by sampling the input voltage and setting the valley activation position under different input voltages, can control the operating frequency of the switching power supply system within a certain range under a wide operating input voltage range. This reduces the difference in switching losses caused by input voltage variations, lowers the temperature rise of the power switching transistor, and improves the consistency of system efficiency and load-carrying capacity under high and low voltages. Furthermore, by directly indicating the valley shielding range under high voltage, consistency of operating status can be achieved when switching between light and heavy loads, simplifying system EMC design and reducing system size.

[0156] This invention also provides a switching power supply controller, see reference. Figure 1 The switching power supply controller 20 may include any of the valley selection devices described above.

[0157] The valley selection device is located inside the switching power supply controller 20 and is connected to the voltage feedback port FB, the gate drive port GATE, and the input voltage sampling port VIN. It can control the valley position of the power switch M1 in the next switching cycle based on the load size and input voltage changes during the current switching cycle of the power switch M1.

[0158] An embodiment of the present invention provides a switching power supply system, the system including the switching power supply controller described above.

[0159] This invention also provides another computer-readable storage medium storing a calculation program, which is executed by a processor to implement the steps of any of the valley-gate methods described in the above embodiments, and will not be repeated here.

[0160] In specific implementations, the computer-readable storage medium may include ROM, RAM, disk, or optical disk, etc.

[0161] Regarding the modules / units included in the various devices and products described in the above embodiments, they can be software modules / units, hardware modules / units, or a combination of both. For example, for various devices and products applied to or integrated into a chip, all of their modules / units can be implemented using hardware methods such as circuits, or at least some modules / units can be implemented using software programs that run on a processor integrated within the chip, while the remaining (if any) modules / units can be implemented using hardware methods such as circuits; for various devices and products applied to or integrated into a chip module, all of their modules / units can be implemented using hardware methods such as circuits, and different modules / units can be located in the same component (e.g., chip, circuit module, etc.) or different components of the chip module, or at least some modules / units can be implemented using hardware methods such as circuits. The components can be implemented using software programs that run on the processor integrated within the chip module. The remaining (if any) modules / units can be implemented using hardware methods such as circuits. For various devices and products applied to or integrated into the terminal, each of its components / units can be implemented using hardware methods such as circuits. Different modules / units can be located in the same component (e.g., chip, circuit module, etc.) or in different components within the terminal. Alternatively, at least some modules / units can be implemented using software programs that run on the processor integrated within the terminal, while the remaining (if any) modules / units can be implemented using hardware methods such as circuits.

[0162] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A valley selection method applied to a switching power supply system; the switching power supply system comprising: Transformer and power switching transistor connected to the transformer; The power switch is used to determine whether the transformer supplies power to the load of the switching power supply system; the method comprises: The load and input voltage of the switching power supply system during the current switching cycle of the power switch are detected. Based on the detection result of the load size in the current switching cycle, a valley identification signal matching the load size in the current switching cycle is generated; the valley identification signal is used to indicate the valley identification corresponding to the power switch tube when it is turned on in the next switching cycle under the load size in the current switching cycle. Based on the detection result of the input voltage magnitude in the current switching cycle, a valley shielding signal is generated. The valley shielding signal is used to indicate the valley shielding range when the power switch is turned on in the next switching cycle. Based on the valley bottom identification signal and the valley bottom shielding signal, a valley bottom selection signal is generated to control the power switch to conduct in the valley selected by the valley bottom selection signal in the next switching cycle; The valley selected by the valley selection signal is the valley outside the valley shielding range indicated by the valley shielding signal.

2. The valley bottom selection method as described in claim 1, characterized in that, The generation of a valley shielding signal based on the detection result of the input voltage magnitude within the current switching cycle includes: Determine the input voltage range within the current switching cycle; Based on the determined input voltage range, the corresponding valley shielding range is determined; The valley shielding signal is generated based on the determined valley shielding range.

3. The valley bottom selection method as described in claim 2, characterized in that, The generation of a valley shielding signal based on the detection result of the input voltage magnitude within the current switching cycle includes: Determine whether the input voltage is greater than a preset voltage threshold during the current switching cycle; When the input voltage is greater than a preset voltage threshold during the current switching cycle, valley shielding range indication information is received. The valley shielding signal is generated based on the received valley shielding range indication information.

4. The valley bottom selection method as described in claim 1, characterized in that, The process of generating a valley selection signal based on the valley bottom identification signal and the valley bottom shielding signal includes: When the valley bottom indicator signal is located within the shielding range indicated by the valley bottom shielding signal, the Kth valley bottom after the shielding range indicated by the valley bottom shielding signal is taken as the valley bottom when the power switch is turned on in the next switching cycle; where K is a positive integer. When the valley bottom indicator signal indicates that the valley bottom is outside the shielding range indicated by the valley bottom shielding signal, the valley bottom indicator signal indicates that the valley bottom is taken as the valley bottom when the power switch tube is turned on in the next switching cycle.

5. The valley bottom selection method as described in claim 4, characterized in that, K＝1。 6. A valley-bottom gating device, applied to a switching power supply system; the switching power supply system comprising: Transformer and power switching transistor connected to the transformer; The power switch is used to determine whether the transformer supplies power to the load of the switching power supply system; characterized in that the device comprises: The load-corresponding valley generation unit is adapted to detect the load size of the switching power supply system during the current switching cycle of the power switch transistor, and generate a valley identification signal that matches the load size during the current switching cycle based on the detection result of the load size during the current switching cycle; the valley identification signal is used to indicate the valley identification corresponding to the power switch transistor when it is turned on in the next switching cycle under the load size during the current switching cycle. Valley shielding unit is adapted to detect the input voltage of the power switch system during the current switching cycle of the power switch transistor, and generate a valley shielding signal based on the detection result of the input voltage during the current switching cycle. The valley shielding signal is used to indicate the valley shielding range when the power switch transistor is turned on in the next switching cycle. Valley selection unit is adapted to generate a valley selection signal based on the valley identification signal and the valley shielding signal, so as to control the power switch to conduct in the valley selected by the valley selection signal in the next switching cycle; The valley selected by the valley selection signal is the valley outside the valley shielding range indicated by the valley shielding signal.

7. The valley bottom selection device as described in claim 6, characterized in that, The load-corresponding valley generation unit includes: A bidirectional encoding circuit, with its input terminal connected to the voltage feedback port of the switching power supply system, is adapted to detect the load magnitude of the switching power supply system during the current switching cycle of the power switch transistor and generate a corresponding pulse encoding sequence. The load-corresponding valley logic generation circuit is connected to the bidirectional encoding circuit. It is adapted to determine the load size in the current switching cycle based on the detection result of the load size in the current switching cycle, select the valley corresponding to the power switch when it is turned on in the next switching cycle based on the load size, and generate a valley identification signal representing the selected valley position.

8. The valley bottom selection device as described in claim 6, characterized in that, The valley floor shielding unit includes: The first input voltage comparison circuit is adapted to be connected to the input voltage sampling port of the switching power supply system and to determine the input voltage range in the current switching cycle. The first valley shielding range determination circuit is suitable for determining the corresponding valley shielding range based on the determined input voltage range and generating the corresponding valley shielding signal.

9. The valley bottom selection device as described in claim 8, characterized in that, The first input voltage comparison circuit includes: a first comparison sub-circuit, N-2 second comparison sub-circuits, and N-2 NOR gates, where N is the number of input voltage ranges; The first comparison sub-circuit includes a first comparator, and each of the N-2 second comparison sub-circuits includes a second comparator and an NOT gate connected to the second comparator. The first input terminal of the first comparator and each of the second comparators are connected to the input voltage sampling port of the switching power supply system, and the second input terminal is connected to each reference voltage output terminal. The first comparator circuit and the first second comparator circuit, as well as adjacent second comparator circuits, are connected by NOR gates.

10. The valley bottom selection device as described in claim 9, characterized in that, The first comparator circuit also includes a first buffer connected to the first comparator, and the second comparator circuit at the end also includes a second buffer connected to a NAND gate.

11. The valley bottom selection device as described in claim 9 or 10, characterized in that, The valley floor shielding unit also includes: The first input voltage detection circuit has its input terminal connected to the input voltage sampling port of the switching power supply system and its output terminal connected to the first input voltage comparison circuit. It is adapted to detect the input voltage of the switching power supply system based on the input information of the input voltage sampling port of the switching power supply system.

12. The valley bottom selection device as described in claim 6, characterized in that, The valley floor shielding unit includes: The second input voltage comparison circuit is adapted to determine whether the input voltage in the current switching cycle is greater than a preset voltage threshold. The receiving circuit is adapted to receive valley shielding range indication information when the input voltage is greater than a preset voltage threshold during the current switching cycle; The second valley shielding range determination circuit is adapted to generate the valley shielding signal based on the received valley shielding range indication information.

13. The valley bottom selection device as described in claim 12, characterized in that, The receiving circuit includes a power-on configuration sub-circuit, which is connected to the valley shielding range indication port of the switching power supply system. It is adapted to select the valley shielding range of the power switching transistor in high-voltage mode through the input information of the valley shielding range indication port, and generate a corresponding valley shielding signal.

14. The valley bottom selection device as described in claim 12, characterized in that, The valley shielding unit further includes: a second input voltage detection circuit, with its input terminal connected to the input voltage sampling port of the switching power supply system and its output terminal connected to the second input voltage comparison circuit, adapted to detect the input voltage of the switching power supply system based on the input information of the input voltage sampling port of the switching power supply system.

15. The valley bottom selection device as described in claim 6, characterized in that, The valley selection unit is adapted to, when the valley identifier indicated by the valley identifier signal is within the shielding range indicated by the valley shielding signal, to take the Kth valley after the shielding range indicated by the valley shielding signal as the valley when the power switch is turned on in the next switching cycle; and when the valley identifier indicated by the valley identifier signal is outside the shielding range indicated by the valley shielding signal, to take the valley identifier indicated by the valley identifier signal as the valley when the power switch is turned on in the next switching cycle. Where K is a positive integer.

16. The valley bottom selection device as described in claim 6, characterized in that, Also includes: Valley bottom update unit, connected to valley bottom selection unit, is adapted to update the valley bottom selected when the power switch is turned on in the next switching cycle based on the valley bottom selection signal.

17. A switching power supply controller, characterized in that, Includes the valley bottom selection device as described in any one of claims 6 to 16.

18. A switching power supply system, characterized in that, Includes the switching power supply controller as described in claim 17.

19. A computer-readable storage medium having a computer program stored thereon, characterized in that, The computer program is executed by a processor to implement the steps of the method according to any one of claims 1 to 5.

Images