A control device of a switching power supply, a switching power supply, and a control method thereof

Abstract

The application discloses a kind of control device of switching power supply, switching power supply and its control method, the device includes: dynamic working mode selection circuit, the primary side current of high-frequency transformer is detected, the load condition of switching power supply is determined, in the compensation circuit of different mode of pre-set, corresponding compensation circuit is matched, voltage compensation is carried out, and compensation voltage is obtained, and it is recorded as current compensation voltage;Error detection circuit, based on the output voltage of high-frequency transformer, compared with the reference voltage of pre-set, and obtain first error voltage;And, for the sum of first error voltage and current compensation voltage, as the feedback voltage of feedback loop output;Power supply control chip, according to the feedback voltage of feedback loop output, control the input voltage of high-frequency transformer.The scheme, according to the primary side current of high-frequency transformer in switching power supply, determine the load condition of switching power supply, match appropriate compensation circuit, ensure dynamic response under different load conditions.

Description

Technical Field

[0001] This invention belongs to the field of switching power supply technology, specifically relating to a control device, a switching power supply and its control method, and more particularly to a control device, a switching power supply and its control method for a dynamic operating mode. Background Technology

[0002] Switching power supplies are widely used due to their simple structure and ability to provide multiple DC outputs. In the design of a switching power supply, the performance of the feedback loop determines its accuracy and overall performance; therefore, the design of the feedback loop is crucial for a switching power supply system.

[0003] Based on whether the output inductor current is continuous, switching power supplies are classified into two operating modes: continuous mode (CCM) and discontinuous mode (DCM). Discontinuous mode is used under light loads, while continuous mode is used under heavy loads. To adapt the switching power supply to these two different operating conditions, the compensation network in relevant designs is designed according to the continuous mode principle, operating at the critical point between discontinuous and continuous modes. When the output load of the switching power supply changes, it can transition from continuous mode to discontinuous mode. While this design method accommodates both operating modes, its compensation network is designed for continuous mode. Therefore, the bandwidth of the switching power supply is relatively small in discontinuous mode, resulting in poor dynamic response.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a control device, a switching power supply, and a control method for the switching power supply, to solve the problem in related solutions where the compensation network of the switching power supply is designed according to continuous mode when it is in a critical state between discontinuous and continuous modes. When the load at the output terminal of the switching power supply changes, the switching power supply can transition from continuous mode to discontinuous mode, but the bandwidth of the switching power supply is relatively small in discontinuous mode, resulting in poor dynamic response. The invention aims to determine the load condition of the switching power supply based on the primary current of the high-frequency transformer in the switching power supply, and match a suitable compensation circuit according to the load condition, thereby ensuring the dynamic response of the switching power supply under different load conditions.

[0006] This invention provides a control device for a switching power supply, wherein the switching power supply has a high-frequency transformer; the control device for the switching power supply includes: a power control chip and a feedback loop; the feedback loop includes: a dynamic operating mode selection circuit and an error detection circuit; wherein, the dynamic operating mode selection circuit is used to detect the primary current of the high-frequency transformer, determine the load condition of the switching power supply based on the primary current of the high-frequency transformer, and match a corresponding compensation circuit in a preset compensation circuit of different modes according to the load condition of the switching power supply, denoted as the matching compensation circuit; the matching compensation circuit is used to perform voltage compensation based on the output voltage of the high-frequency transformer to obtain a compensation voltage, denoted as the current compensation voltage; the error detection circuit is used to compare the output voltage of the high-frequency transformer with a preset reference voltage to obtain a first error voltage; and to use the sum of the first error voltage and the current compensation voltage as the feedback voltage output by the feedback loop; the power control chip is used to control the conduction time of the switching transistor on the primary side of the high-frequency transformer in the current cycle according to the feedback voltage output by the feedback loop, so as to adjust the energy stored in the primary inductance of the high-frequency transformer in the current cycle, thereby realizing the control of the output voltage of the high-frequency transformer.

[0007] In some embodiments, the dynamic operating mode selection circuit includes: an operating mode detection circuit, a mode selection circuit, and compensation circuits for different modes; wherein, the operating mode detection circuit is used to detect the primary current of the high-frequency transformer; the mode selection circuit is used to determine the load condition of the switching power supply based on the primary current of the high-frequency transformer in the switching power supply, and to match the corresponding compensation circuit in the preset compensation circuits for different modes according to the load condition of the switching power supply; wherein, the compensation circuits for different modes include: a CCM compensation circuit and a DCM compensation circuit; the CCM compensation circuit and the DCM compensation circuit are arranged in parallel at the output terminal of the mode selection circuit, and are also arranged in parallel between the input terminal of the high-frequency transformer output voltage of the error detection circuit and the output terminal of the error detection circuit.

[0008] In some embodiments, the operating mode detection circuit includes: a current sampling module and an amplification module; wherein, the current sampling module is disposed between the primary side of the high-frequency transformer and ground, and is used to sample the current of the primary side of the high-frequency transformer to obtain a primary side current sampling signal of the high-frequency transformer; the amplification module is disposed at the output end of the current sampling module, and is used to amplify the primary side current sampling signal of the high-frequency transformer to obtain an amplified primary side current sampling signal of the high-frequency transformer, which is used as the primary side current of the high-frequency transformer.

[0009] In some embodiments, the mode selection circuit includes: a hysteresis comparison module and a switch module; the switch module has a control terminal, a first connection terminal, and a second connection terminal; wherein, the output terminal of the operating mode detection circuit is input to the first input terminal of the hysteresis comparison module; the second input terminal of the hysteresis comparison module is used to input a preset comparison threshold; the output terminal of the hysteresis comparison module is connected to the control terminal of the switch module; the first connection terminal of the switch module is connected to the CCM compensation circuit in the compensation circuit of the different modes; the second connection terminal of the switch module is connected to the DCM compensation circuit in the compensation circuit of the different modes.

[0010] In some embodiments, the switching module uses a relay; wherein the coil of the relay serves as the control terminal of the switching module; the first contact of the relay serves as the first connection terminal of the switching module; and the second contact of the relay serves as the second connection terminal of the switching module.

[0011] In some implementations, the preset comparison thresholds include: a first comparison threshold and a second comparison threshold, wherein the first comparison threshold is greater than the second comparison threshold; when the primary current of the high-frequency transformer output by the operating mode detection circuit is greater than the first comparison threshold, the load condition of the switching power supply is determined to be light load; when the load condition of the switching power supply is light load, the control terminal of the switching module is connected to the second connection terminal of the switching module, and the matching compensation circuit is a DCM compensation circuit; when the primary current of the high-frequency transformer output by the operating mode detection circuit is less than the second comparison threshold, the load condition of the switching power supply is determined to be heavy load; when the load condition of the switching power supply is heavy load, the control terminal of the switching module is connected to the first connection terminal of the switching module, and the matching compensation circuit is a CCM compensation circuit.

[0012] In conjunction with the above-described device, the present invention further provides a switching power supply, comprising: the control device for the switching power supply described above.

[0013] In conjunction with the aforementioned switching power supply, this invention further provides a control method for a switching power supply, comprising: detecting the primary current of the high-frequency transformer; determining the load condition of the switching power supply based on the primary current of the high-frequency transformer in the switching power supply; matching a corresponding compensation circuit in a preset compensation circuit of different modes according to the load condition of the switching power supply, denoted as the matching compensation circuit; performing voltage compensation based on the output voltage of the high-frequency transformer to obtain a compensation voltage, denoted as the current compensation voltage; comparing the output voltage of the high-frequency transformer with a preset reference voltage to obtain a first error voltage; and using the sum of the first error voltage and the current compensation voltage as the feedback voltage output by the feedback loop; controlling the on-time of the switching transistor on the primary side of the high-frequency transformer in the current cycle according to the feedback voltage output by the feedback loop, so as to adjust the energy stored in the primary inductance of the high-frequency transformer in the current cycle, thereby realizing the control of the output voltage of the high-frequency transformer.

[0014] In some embodiments, the compensation circuits of different modes include: a CCM compensation circuit and a DCM compensation circuit; detecting the primary current of the high-frequency transformer, determining the load condition of the switching power supply based on the primary current of the high-frequency transformer in the switching power supply, and matching the corresponding compensation circuit in the preset compensation circuits of different modes according to the load condition of the switching power supply, denoted as the matching compensation circuit, includes: sampling the primary current of the high-frequency transformer to obtain the primary current sampling signal of the high-frequency transformer; amplifying the primary current sampling signal of the high-frequency transformer to obtain the amplified primary current sampling signal of the high-frequency transformer, which is used as the primary current of the high-frequency transformer; in the working mode When the primary current of the high-frequency transformer output by the detection circuit is greater than the first comparison threshold, the load condition of the switching power supply is determined to be light load. When the load condition of the switching power supply is light load, the control terminal of the switching module is connected to the second connection terminal of the switching module, and the matching compensation circuit is a DCM compensation circuit. When the primary current of the high-frequency transformer output by the working mode detection circuit is less than the second comparison threshold, the load condition of the switching power supply is determined to be heavy load. When the load condition of the switching power supply is heavy load, the control terminal of the switching module is connected to the first connection terminal of the switching module, and the matching compensation circuit is a CCM compensation circuit.

[0015] Therefore, the solution of the present invention, through a closed-loop control system for a switching power supply, is based on a feedback loop composed of a compensation network and an error detection current, and a dynamic operating mode selection circuit is set in the compensation network. This dynamic operating mode selection circuit detects the primary current of the high-frequency transformer in the switching power supply, determines the load condition of the switching power supply based on the primary current of the high-frequency transformer, and matches the corresponding compensation circuit according to the load condition of the switching power supply. Specifically, when the load condition of the switching power supply is heavy, a CCM compensation network is matched; when the load condition of the switching power supply is light, a DCM compensation network is matched. Thus, by determining the load condition of the switching power supply based on the primary current of the high-frequency transformer and matching a suitable compensation circuit according to the load condition, the dynamic response of the switching power supply under different load conditions is at least guaranteed.

[0016] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a structure of an embodiment of the control device for the switching power supply of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of an embodiment of the switching power supply system in the relevant scheme;

[0020] Figure 3 A schematic diagram of the structure of an embodiment of a switching power supply system with dynamic operating mode;

[0021] Figure 4 A schematic diagram of one embodiment of a dynamic operating mode selection circuit;

[0022] Figure 5 This is a flowchart illustrating an embodiment of the control method for a switching power supply of the present invention;

[0023] Figure 6 This is a flowchart illustrating an embodiment of the control method for a switching power supply of the present invention, which matches a corresponding compensation circuit in a preset compensation circuit of different modes according to the load condition of the switching power supply. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] A switching power supply system, or its control system, is a closed-loop control system consisting of an outer-loop voltage feedback and an inner-loop current feedback. The feedback loop of the switching power supply is a transfer function. The compensation network is part of this feedback loop. The purpose of the compensation network is to improve the dynamic response of the switching power supply and make the closed-loop control system more stable. The calculated compensation network differs between continuous mode (CCM) and discontinuous mode (DCM) of the switching power supply. The compensation network is designed for continuous mode, suitable for heavy load conditions; however, under light load conditions, if the compensation network fails to meet the requirements, the output voltage of the switching power supply will be abnormal, and the output voltage may not be adjustable to the rated output voltage value.

[0026] Specifically, Figure 2 This is a schematic diagram of the structure of one embodiment of the switching power supply system in the relevant scheme. For example... Figure 2 As shown, the switching power supply system in the relevant scheme mainly consists of a power control chip, a high-frequency transformer, and a feedback loop. The output of the power control chip is fed back to the feedback terminal of the power control chip via the high-frequency transformer. The feedback loop includes an error detection circuit and a compensation circuit. The voltage sampling terminal of the error detection circuit is used to input the output voltage of the high-frequency transformer; the voltage reference terminal of the error detection circuit is used to input a reference voltage; the voltage sampling terminal of the error detection circuit is connected to the output terminal of the error detection circuit after passing through the compensation circuit; the output terminal of the error detection circuit outputs the error detection voltage Verr; the error detection voltage Verr is input to the feedback terminal of the power control chip. The high-frequency transformer is a power transformer with an operating frequency exceeding the intermediate frequency (10kHz). It is mainly used in high-frequency switching power supplies as a high-frequency switching power supply transformer, and is also used in high-frequency inverter power supplies and high-frequency inverter welding machines as a high-frequency inverter power supply transformer.

[0027] To ensure the stability of the closed-loop feedback loop of the switching power supply system, a compensation circuit is used to obtain sufficient phase and gain margins. The feedback loop samples the voltage from the output of the high-frequency transformer and compares it with a set voltage value (i.e., a reference voltage). The error between the two (i.e., the error detection voltage Verr) is sent to the feedback terminal of the power control chip. Upon receiving the error result, the power control chip adjusts and controls the duty cycle of the drive signals of the switching transistors in the switching power supply to achieve closed-loop stable control of the high-frequency transformer's output voltage. The compensation circuit is generally designed in continuous mode under critical conditions. Although it can operate under light loads, it cannot guarantee a sufficiently large bandwidth, resulting in poor dynamic response.

[0028] Therefore, to address the issue in related solutions where the compensation network of the switching power supply is designed in continuous mode at the critical state between discontinuous and continuous modes, the power supply can transition from continuous to discontinuous mode when the output load changes. However, in discontinuous mode, the bandwidth is relatively small, resulting in poor dynamic response. This invention proposes a control method for a switching power supply, specifically a dynamic operating mode control method. This method detects the primary current of the transformer and determines the load condition at the output of the power supply. Based on the detected primary current, a suitable loop compensation network is matched, allowing the power supply to switch appropriate feedback loops according to the load conditions. This ensures good steady-state performance and dynamic response of the power supply under different load conditions at its output.

[0029] According to an embodiment of the present invention, a control device for a switching power supply is provided. See also... Figure 1 The diagram shows a structural schematic of an embodiment of the device of the present invention. The switching power supply has a high-frequency transformer; the control device of the switching power supply includes: a power control chip and a feedback loop; the feedback loop includes: a dynamic operating mode selection circuit and an error detection circuit.

[0030] The dynamic operating mode selection circuit is used to detect the primary current of the high-frequency transformer, determine the load condition of the switching power supply based on the primary current of the high-frequency transformer in the switching power supply, and match the corresponding compensation circuit in the preset compensation circuit of different modes according to the load condition of the switching power supply, which is denoted as the matching compensation circuit.

[0031] The matching compensation circuit is used to perform voltage compensation based on the output voltage of the high-frequency transformer to obtain a compensation voltage, which is denoted as the current compensation voltage.

[0032] The error detection circuit is used to compare the output voltage of the high-frequency transformer with a preset reference voltage to obtain a first error voltage; and to use the sum of the first error voltage and the current compensation voltage as the feedback voltage output by the feedback loop.

[0033] The power control chip is used to control the conduction time of the switching transistor on the primary side of the high-frequency transformer in the current cycle according to the feedback voltage output by the feedback loop, so as to adjust the energy stored in the primary inductance of the high-frequency transformer in the current cycle and realize the control of the output voltage of the high-frequency transformer.

[0034] Specifically, the operation of a flyback switching power supply is as follows: When the primary-side switching transistor of the high-frequency transformer is turned on, current flows through the primary-side inductor of the high-frequency transformer and stores energy. Because the terminals of the primary and secondary windings of the high-frequency transformer are opposite, the secondary diode is reverse-biased and cut off, and the current on the load is provided by the output capacitor. When the primary-side switching transistor of the high-frequency transformer is turned off, the secondary rectifier diode is forward-biased, and the energy stored in the high-frequency transformer is provided to the output capacitor and the load. The power supply control chip adjusts the energy stored in the primary inductor of the transformer in the current cycle by controlling the on-time of the primary-side switching transistor of the high-frequency transformer (generally using PWM control; the control chip for this transistor is built-in, but can be external if the control chip is not available), thereby forming a closed-loop control system to stabilize the output voltage.

[0035] The present invention proposes a control scheme for the dynamic operating mode of a switching power supply. By detecting the primary current of the transformer in the switching power supply, the load condition at the output of the switching power supply is determined based on the detected primary current. Based on the load condition at the output of the switching power supply, a suitable loop compensation network is matched, enabling the switching power supply to switch the appropriate feedback loop according to the load condition. This ensures that the switching power supply has good steady-state performance and dynamic response under different load conditions at the output of the switching power supply.

[0036] In some implementations, the dynamic operating mode selection circuit includes: an operating mode detection circuit, a mode selection circuit, and compensation circuits for different modes.

[0037] The operating mode detection circuit is used to detect the primary current of the high-frequency transformer.

[0038] The mode selection circuit is used to determine the load condition of the switching power supply based on the primary current of the high-frequency transformer in the switching power supply, and to match the corresponding compensation circuit in different preset modes according to the load condition of the switching power supply. The compensation circuits for different modes include a CCM compensation circuit and a DCM compensation circuit; the CCM compensation circuit and the DCM compensation circuit are arranged in parallel at the output terminal of the mode selection circuit, and are also arranged in parallel between the input terminal of the high-frequency transformer output voltage and the output terminal of the error detection circuit.

[0039] Specifically, Figure 3 This is a schematic diagram of a system embodiment of a switching power supply with dynamic operating modes. (See diagram below.) Figure 3 As shown, the dynamic operating mode switching power supply system of the present invention includes: a power control chip, a high-frequency transformer, and a feedback loop. The output terminal of the power control chip outputs a voltage after passing through the high-frequency transformer; the output voltage is fed back to the feedback terminal of the power control chip after passing through the feedback loop; the primary current sampling terminal of the high-frequency transformer is also connected to the feedback loop. The feedback loop includes: an error detection circuit and a dynamic operating mode selection circuit. The voltage sampling terminal of the error detection circuit is used to input the output voltage of the high-frequency transformer; the voltage reference terminal of the error detection circuit is used to input a reference voltage; the voltage sampling terminal of the error detection circuit, after passing through the dynamic operating mode selection circuit, is connected to the output terminal of the error detection circuit; the output terminal of the error detection circuit outputs an error detection voltage Verr; the error detection voltage Verr is input to the feedback terminal of the power control chip.

[0040] The dynamic operating mode selection circuit includes: an operating mode detection circuit, a mode selection circuit, and compensation circuits for different modes. The operating mode detection circuit, the mode selection circuit, and the compensation circuits for different modes are connected in sequence; the output terminal of the mode selection circuit is also connected to the output terminal of the error detection circuit; the voltage sampling terminal of the error detection circuit is also connected to the output terminal of the compensation circuit for different modes.

[0041] See also Figure 3 As shown in the example, the control scheme for the dynamic operating mode of the switching power supply in the present invention first determines the current operating mode of the switching power supply through an operating mode detection circuit; then, through a mode selection circuit, a suitable compensation circuit is selected from the compensation circuits of different modes, so that the switching power supply operates in the optimal state.

[0042] In some embodiments, the operating mode detection circuit includes a current sampling module and an amplification module, wherein the current sampling module is such as a current sampling resistor R1, and the amplification module is such as an amplification circuit U1.

[0043] The current sampling module is disposed between the primary side of the high-frequency transformer and ground, and is used to sample the current of the primary side of the high-frequency transformer to obtain the primary side current sampling signal of the high-frequency transformer. Specifically, the first connection terminal of the current sampling module is connected to the primary side of the high-frequency transformer, and the second connection terminal of the current sampling module is grounded.

[0044] The amplification module is located at the output end of the current sampling module and is used to amplify the primary current sampling signal of the high-frequency transformer to obtain the amplified primary current sampling signal of the high-frequency transformer, which is used as the primary current of the high-frequency transformer. Specifically, the first input end of the amplification module is connected to the common terminal of the primary side of the high-frequency transformer and the current sampling module; the second input end of the amplification module is grounded.

[0045] Specifically, Figure 4 A schematic diagram of one embodiment of a circuit for selecting a dynamic operating mode. (See diagram below.) Figure 4 As shown, in the dynamic operating mode selection circuit, the operating mode detection circuit includes: a current sampling resistor R1 and an amplifier circuit U1; the compensation circuits for different modes include: a CCM compensation circuit and a DCM compensation circuit.

[0046] The output of the switching power supply control chip is connected to the input of the high-frequency transformer. The output of the high-frequency transformer is connected to the voltage sampling terminal of the error detection circuit. The reference voltage is input to the voltage reference terminal of the error detection circuit. The primary winding of the high-frequency transformer is connected to the first connection terminal of the current sampling resistor R1, and the second connection terminal of the current sampling resistor R1 is grounded. The first input terminal of the amplifier circuit U1 is connected to the first connection terminal of the current sampling resistor R1; the second input terminal of the amplifier circuit U1 is connected to the second connection terminal of the current sampling resistor R1; the output terminal of the amplifier circuit U1 outputs voltage Uc.

[0047] See Figure 3 and Figure 4 In the example shown, the control scheme for the dynamic operating mode of the switching power supply in this invention includes an operating mode detection circuit consisting of a current sampling circuit R1 and an amplifier circuit U1. Once the high-frequency transformer is designed, its inductance value will not change. At this point, the current required by the load of the switching power supply is crucial in determining its operating mode. Since the load-side current of the switching power supply is proportional to the primary current of the high-frequency transformer, this invention determines the current load condition of the switching power supply by sampling the primary current of the high-frequency transformer. The sampled signal of the primary current of the high-frequency transformer is amplified appropriately by the amplifier circuit U1.

[0048] In some implementations, the mode selection circuit includes a hysteresis comparison module and a switching module, such as a hysteresis comparison circuit U2, and a relay K1; the switching module has a control terminal, a first connection terminal, and a second connection terminal.

[0049] The output of the working mode detection circuit is input to the first input of the hysteresis comparison module; the second input of the hysteresis comparison module is used to input a preset comparison threshold; the output of the hysteresis comparison module is connected to the control terminal of the switch module; the first connection terminal of the switch module is connected to the CCM compensation circuit in the compensation circuit of the different modes; and the second connection terminal of the switch module is connected to the DCM compensation circuit in the compensation circuit of the different modes.

[0050] Preferably, the switch module uses a relay, such as relay K1; wherein, the coil of the relay serves as the control terminal of the switch module; the first contact of the relay serves as the first connection terminal of the switch module; and the second contact of the relay serves as the second connection terminal of the switch module.

[0051] Specifically, such as Figure 4 As shown, the mode selection circuit includes a hysteresis comparator circuit U2 and a normally closed relay K1. The output voltage Uc of the amplifier circuit U1 is input to the first input terminal of the hysteresis comparator circuit, and the voltage reference value is input to the second input terminal of the hysteresis comparator circuit. The output terminal of the hysteresis comparator circuit is connected to the control terminal of the relay K1. The first connection terminal of the relay K1 is connected to the CCM compensation circuit, and the second connection terminal of the relay K1 is connected to the DCM compensation circuit.

[0052] See Figure 3 and Figure 4 In the example shown, the control scheme for the dynamic operating mode of the switching power supply in this invention includes an operating mode detection circuit composed of a hysteresis comparator circuit U2 and a relay K1. The sampling signal of the primary current of the high-frequency transformer is amplified by an appropriate ratio through the amplifier circuit U1 and then sent to the first input terminal of the hysteresis comparator circuit U2.

[0053] In some implementations, the preset comparison thresholds include: a first comparison threshold and a second comparison threshold, wherein the first comparison threshold is greater than the second comparison threshold.

[0054] Specifically, when the primary current of the high-frequency transformer output by the working mode detection circuit is greater than the first comparison threshold, the load condition of the switching power supply is determined to be light load; when the load condition of the switching power supply is light load, the control terminal of the switching module is connected to the second connection terminal of the switching module, and the matching compensation circuit is a DCM compensation circuit.

[0055] If the primary current of the high-frequency transformer output by the working mode detection circuit is less than the second comparison threshold, the load condition of the switching power supply is determined to be heavy load; when the load condition of the switching power supply is heavy load, the control terminal of the switching module is connected to the first connection terminal of the switching module, and the matching compensation circuit is a CCM compensation circuit.

[0056] Specifically, see Figure 4 In the example shown, the hysteresis comparator circuit U2 uses a non-inverting input configuration. The voltage reference value, i.e., the comparison threshold, input to the second input terminal (i.e., the voltage reference terminal) of the hysteresis comparator circuit U2 is designed as the first comparison threshold U. oh =V ref1 Second comparison threshold U ol =V ref2 .

[0057] The comparison threshold is determined and set based on the current value of the primary side of the high-frequency transformer under different modes of the actual switching power supply, as well as the amplification factor of the amplifier circuit U1. The hysteresis voltage is also set according to actual requirements. ref1 Greater than V ref2 When the load is heavy, the voltage U output by the operating mode detection circuit... c Less than the second comparison threshold U ol When the hysteresis comparator circuit U2 outputs a low level, the coil of relay K1 is de-energized, thus the contacts of relay K1 connect to the CCM compensation network; similarly, when the load is light, the voltage U output by the operating mode detection circuit... c Greater than the first comparison threshold U oh When the hysteresis comparator circuit U2 outputs a high level, the coil of relay K1 is de-energized, and the contacts of relay K1 connect to the DCM compensation network. This allows the switching power supply to match appropriate compensation network parameters under different load conditions, and can better achieve the switching between two operating modes. This ensures that the output voltage of the switching power supply remains stable when the output load changes suddenly, while also having good dynamic response characteristics.

[0058] See Figure 3 and Figure 4As shown in the example, in the control scheme of the dynamic working mode of the switching power supply in the present invention, the compensation circuits for different modes consist of a CCM compensation circuit and a DCM compensation circuit. By using the different working modes of the switching power supply, the distribution of zeros and poles is calculated through the function of the feedback loop, thereby designing different compensation networks.

[0059] The present invention employs a hardware circuit to implement a control scheme for the dynamic operating mode of a switching power supply. The switching power supply uses a current-voltage closed-loop control method. The current sampling circuit can utilize the existing output current sampling circuit, ensuring the stability of the switching power supply's output voltage during load changes and improving the system's dynamic response speed. This allows the switching power supply's operating mode to match the load conditions, enabling switching between the two modes. Thus, it solves the problem of mismatch between the switching power supply's operating mode and load conditions, as well as the problem of poor dynamic response during load changes. It ensures that after switching operating modes and adjusting the compensation network during load changes, the output voltage remains stable, while maintaining good dynamic response characteristics. Load changes refer to a change in the load on the power supply. Generally, a heavy load indicates a decrease in load resistance, requiring a larger current; a light load indicates an increase in load resistance, requiring a smaller current.

[0060] The technical solution of this invention, through a closed-loop control system for a switching power supply, is based on a feedback loop composed of a compensation network and an error detection current. A dynamic operating mode selection circuit is set in the compensation network. This dynamic operating mode selection circuit detects the primary current of the high-frequency transformer in the switching power supply, determines the load condition of the switching power supply based on the primary current, and matches a corresponding compensation circuit according to the load condition. Specifically, when the load condition of the switching power supply is heavy, a CCM compensation network is matched; when the load condition is light, a DCM compensation network is matched. Thus, by determining the load condition of the switching power supply based on the primary current of the high-frequency transformer and matching a suitable compensation circuit according to the load condition, at least the dynamic response of the switching power supply under different load conditions is guaranteed.

[0061] According to an embodiment of the present invention, a switching power supply corresponding to a control device for a switching power supply is also provided. This switching power supply may include the control device for the switching power supply described above.

[0062] Since the processing and functions implemented by the switching power supply in this embodiment are basically the same as those in the embodiments, principles and examples of the device, any details not covered in this embodiment can be found in the relevant descriptions in the foregoing embodiments, and will not be repeated here.

[0063] The technical solution of this invention, through a closed-loop control system for a switching power supply, is based on a feedback loop consisting of a compensation network and an error detection current. A dynamic operating mode selection circuit is set in the compensation network. This dynamic operating mode selection circuit detects the primary current of the high-frequency transformer in the switching power supply, determines the load condition of the switching power supply based on the primary current, and matches the corresponding compensation circuit according to the load condition. Specifically, when the load condition of the switching power supply is heavy, a CCM compensation network is matched; when the load condition is light, a DCM compensation network is matched. This ensures that when the load changes abruptly, the power supply switches operating modes and compensation networks to maintain stable output voltage, while also exhibiting good dynamic response characteristics.

[0064] According to embodiments of the present invention, a control method for a switching power supply corresponding to a switching power supply is also provided, such as... Figure 5 The diagram shows a flowchart of an embodiment of the method of the present invention. The control method of the switching power supply may include steps S110 to S140.

[0065] In step S110, the primary current of the high-frequency transformer is detected, the load condition of the switching power supply is determined based on the primary current of the high-frequency transformer in the switching power supply, and a corresponding compensation circuit is matched in the preset compensation circuit of different modes according to the load condition of the switching power supply, which is denoted as the matching compensation circuit.

[0066] In some implementations, the different modes of compensation circuits include: CCM compensation circuit and DCM compensation circuit.

[0067] In step S110, the primary current of the high-frequency transformer is detected, and the load condition of the switching power supply is determined based on the primary current of the high-frequency transformer in the switching power supply. The corresponding compensation circuit is matched in the preset compensation circuit of different modes according to the load condition of the switching power supply. This process is referred to as the matching compensation circuit. For details, please refer to the following exemplary description.

[0068] The following is combined Figure 6 The flowchart shown is a schematic diagram of an embodiment of the method of the present invention in which a corresponding compensation circuit is matched in a preset compensation circuit of different modes according to the load of the switching power supply. The specific process of matching the corresponding compensation circuit in the preset compensation circuit of different modes according to the load of the switching power supply in step S110 is further explained, including steps S210 to S240.

[0069] Step S210: Sample the current of the primary side of the high-frequency transformer to obtain the primary side current sampling signal of the high-frequency transformer.

[0070] Step S220: Amplify the primary current sampling signal of the high-frequency transformer to obtain the amplified primary current sampling signal of the high-frequency transformer, which is used as the primary current of the high-frequency transformer.

[0071] Step S230: If the primary current of the high-frequency transformer output by the working mode detection circuit is greater than the first comparison threshold, the load condition of the switching power supply is determined to be light load; when the load condition of the switching power supply is light load, the control terminal of the switching module is connected to the second connection terminal of the switching module, and the matching compensation circuit is a DCM compensation circuit.

[0072] Step S240: If the primary current of the high-frequency transformer output by the working mode detection circuit is less than the second comparison threshold, the load condition of the switching power supply is determined to be heavy load; when the load condition of the switching power supply is heavy load, the control terminal of the switching module is connected to the first connection terminal of the switching module, and the matching compensation circuit is a CCM compensation circuit.

[0073] like Figure 4 As shown, in the dynamic operating mode selection circuit, the operating mode detection circuit includes: a current sampling resistor R1 and an amplifier circuit U1; the compensation circuits for different modes include: a CCM compensation circuit and a DCM compensation circuit. See also... Figure 3 and Figure 4 In the example shown, the control scheme for the dynamic operating mode of the switching power supply in this invention includes an operating mode detection circuit consisting of a current sampling circuit R1 and an amplifier circuit U1. Once the high-frequency transformer is designed, its inductance value will not change. At this point, the current required by the load of the switching power supply is crucial in determining its operating mode. Since the load-side current of the switching power supply is proportional to the primary current of the high-frequency transformer, this invention determines the current load condition of the switching power supply by sampling the primary current of the high-frequency transformer. The sampled signal of the primary current of the high-frequency transformer is amplified appropriately by the amplifier circuit U1.

[0074] The output of the switching power supply control chip is connected to the input of the high-frequency transformer. The output of the high-frequency transformer is connected to the voltage sampling terminal of the error detection circuit. The reference voltage is input to the voltage reference terminal of the error detection circuit. The primary winding of the high-frequency transformer is connected to the first connection terminal of the current sampling resistor R1, and the second connection terminal of the current sampling resistor R1 is grounded. The first input terminal of the amplifier circuit U1 is connected to the first connection terminal of the current sampling resistor R1; the second input terminal of the amplifier circuit U1 is connected to the second connection terminal of the current sampling resistor R1; the output terminal of the amplifier circuit U1 outputs voltage Uc. The mode selection circuit includes a hysteresis comparator circuit U2 and a relay K1, which is a normally closed relay. The output voltage Uc of the amplifier circuit U1 is input to the first input terminal of the hysteresis comparator circuit, the voltage reference value is input to the second input terminal of the hysteresis comparator circuit, and the output terminal of the hysteresis comparator circuit is connected to the control terminal of the relay K1. The first connection terminal of the relay K1 is connected to the CCM compensation circuit, and the second connection terminal of the relay K1 is connected to the DCM compensation circuit. See also Figure 3 and Figure 4 In the example shown, the control scheme for the dynamic operating mode of the switching power supply in this invention includes an operating mode detection circuit composed of a hysteresis comparator circuit U2 and a relay K1. The sampling signal of the primary current of the high-frequency transformer is amplified by an appropriate ratio through the amplifier circuit U1 and then sent to the first input terminal of the hysteresis comparator circuit U2.

[0075] See Figure 4 In the example shown, the hysteresis comparator circuit U2 uses a non-inverting input configuration. The voltage reference value, i.e., the comparison threshold, input to the second input terminal (i.e., the voltage reference terminal) of the hysteresis comparator circuit U2 is designed as the first comparison threshold U. oh =V ref1 Second comparison threshold U ol =V ref2 .

[0076] The comparison threshold is determined and set based on the current value of the primary side of the high-frequency transformer under different modes of the actual switching power supply, as well as the amplification factor of the amplifier circuit U1. The hysteresis voltage is also set according to actual requirements. ref1 Greater than V ref2 When the load is heavy, the voltage U output by the operating mode detection circuit... c Less than the second comparison threshold U ol When the hysteresis comparator circuit U2 outputs a low level, the coil of relay K1 is de-energized, thus the contacts of relay K1 connect to the CCM compensation network; similarly, when the load is light, the voltage U output by the operating mode detection circuit... c Greater than the first comparison threshold U ohWhen the hysteresis comparator circuit U2 outputs a high level, the coil of relay K1 is de-energized, and the contacts of relay K1 connect to the DCM compensation network. This allows the switching power supply to match appropriate compensation network parameters under different load conditions, and can better achieve the switching between two operating modes. This ensures that the output voltage of the switching power supply remains stable when the output load changes suddenly, while also having good dynamic response characteristics.

[0077] In step S120, voltage compensation is performed based on the output voltage of the high-frequency transformer to obtain a compensation voltage, which is recorded as the current compensation voltage.

[0078] At step S130, the output voltage of the high-frequency transformer is compared with a preset reference voltage to obtain a first error voltage; and the sum of the first error voltage and the current compensation voltage is used as the feedback voltage output by the feedback loop.

[0079] In step S140, based on the feedback voltage output by the feedback loop, the conduction time of the switching transistor on the primary side of the high-frequency transformer in the current cycle is controlled to adjust the energy stored in the primary inductance of the high-frequency transformer in the current cycle, thereby controlling the output voltage of the high-frequency transformer.

[0080] The present invention proposes a control scheme for the dynamic operating mode of a switching power supply. By detecting the primary current of the transformer in the switching power supply, the load condition at the output of the switching power supply is determined based on the detected primary current. Based on the load condition at the output of the switching power supply, a suitable loop compensation network is matched, enabling the switching power supply to switch the appropriate feedback loop according to the load condition. This ensures that the switching power supply has good steady-state performance and dynamic response under different load conditions at the output of the switching power supply.

[0081] The present invention employs a hardware circuit to implement a control scheme for the dynamic operating mode of a switching power supply. The switching power supply uses a current-voltage closed-loop control method. The current sampling circuit can utilize the existing output current sampling circuit, ensuring the stability of the switching power supply's output voltage during load changes and improving the system's dynamic response speed. This allows the switching power supply's operating mode to match the load conditions, enabling switching between the two modes. Thus, it solves the problem of mismatch between the switching power supply's operating mode and load conditions, as well as the problem of poor dynamic response during load changes. It ensures that after switching operating modes and adjusting the compensation network during load changes, the output voltage remains stable, while maintaining good dynamic response characteristics. Load changes refer to a change in the load on the power supply. Generally, a heavy load indicates a decrease in load resistance, requiring a larger current; a light load indicates an increase in load resistance, requiring a smaller current.

[0082] Since the processing and functions implemented by the method in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned switching power supply, any details not covered in the description of this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0083] The technical solution of this embodiment, through a closed-loop control system for the switching power supply, is based on a feedback loop composed of a compensation network and an error detection current. A dynamic operating mode selection circuit is set in the compensation network. This dynamic operating mode selection circuit detects the primary current of the high-frequency transformer in the switching power supply, determines the load condition of the switching power supply based on the primary current of the high-frequency transformer, and matches the corresponding compensation circuit according to the load condition. Specifically, when the load condition of the switching power supply is heavy, a CCM compensation network is matched; when the load condition of the switching power supply is light, a DCM compensation network is matched. This allows the switching power supply to switch the appropriate feedback loop according to the load condition, ensuring that the switching power supply has good steady-state performance and dynamic response under different load conditions at the output of the switching power supply.

[0084] In summary, it is readily understood by those skilled in the art that, without conflict, the aforementioned advantageous methods can be freely combined and superimposed.

[0085] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A control device for a switching power supply, characterized in that, The switching power supply includes a high-frequency transformer; the control device of the switching power supply includes a power control chip and a feedback loop; the feedback loop includes a dynamic operating mode selection circuit and an error detection circuit; wherein, The dynamic working mode selection circuit is used to detect the primary current of the high-frequency transformer, determine the load condition of the switching power supply based on the primary current of the high-frequency transformer in the switching power supply, and match the corresponding compensation circuit in the preset compensation circuit of different modes according to the load condition of the switching power supply, which is denoted as the matching compensation circuit. The matching compensation circuit is used to perform voltage compensation based on the output voltage of the high-frequency transformer to obtain a compensation voltage, which is recorded as the current compensation voltage. The error detection circuit is used to compare the output voltage of the high-frequency transformer with a preset reference voltage to obtain a first error voltage; and to use the sum of the first error voltage and the current compensation voltage as the feedback voltage output by the feedback loop. The power control chip is used to control the conduction time of the switching transistor on the primary side of the high-frequency transformer in the current cycle according to the feedback voltage output by the feedback loop, so as to adjust the energy stored in the primary inductance of the high-frequency transformer in the current cycle and realize the control of the output voltage of the high-frequency transformer.

2. The control device for the switching power supply according to claim 1, characterized in that, The dynamic operating mode selection circuit includes: an operating mode detection circuit, a mode selection circuit, and compensation circuits for different modes; wherein, The operating mode detection circuit is used to detect the primary current of the high-frequency transformer; The mode selection circuit is used to determine the load condition of the switching power supply based on the primary current of the high-frequency transformer in the switching power supply, and to match the corresponding compensation circuit in the preset compensation circuit of different modes according to the load condition of the switching power supply. The compensation circuits for different modes include a CCM compensation circuit and a DCM compensation circuit. The CCM compensation circuit and the DCM compensation circuit are arranged in parallel at the output terminal of the mode selection circuit, and are also arranged in parallel between the input terminal of the output voltage of the high-frequency transformer of the error detection circuit and the output terminal of the error detection circuit.

3. The control device for the switching power supply according to claim 2, characterized in that, The operating mode detection circuit includes: a current sampling module and an amplification module; wherein, The current sampling module is disposed between the primary side of the high-frequency transformer and ground, and is used to sample the current of the primary side of the high-frequency transformer to obtain the primary side current sampling signal of the high-frequency transformer. The amplification module is located at the output end of the current sampling module and is used to amplify the primary current sampling signal of the high-frequency transformer to obtain the amplified primary current sampling signal of the high-frequency transformer, which is used as the primary current of the high-frequency transformer.

4. The control device for the switching power supply according to claim 2, characterized in that, The mode selection circuit includes: a hysteresis comparison module and a switching module; the switching module has a control terminal, a first connection terminal, and a second connection terminal; wherein, The output of the working mode detection circuit is input to the first input of the hysteresis comparison module; the second input of the hysteresis comparison module is used to input a preset comparison threshold; the output of the hysteresis comparison module is connected to the control terminal of the switch module; the first connection terminal of the switch module is connected to the CCM compensation circuit in the compensation circuit of the different modes; the second connection terminal of the switch module is connected to the DCM compensation circuit in the compensation circuit of the different modes.

5. The control device for the switching power supply according to claim 4, characterized in that, The switching module uses a relay; wherein, The relay coil serves as the control terminal of the switch module; the first contact of the relay serves as the first connection terminal of the switch module; and the second contact of the relay serves as the second connection terminal of the switch module.

6. The control device for a switching power supply according to claim 4 or 5, characterized in that, in, The preset comparison thresholds include: a first comparison threshold and a second comparison threshold, wherein the first comparison threshold is greater than the second comparison threshold; If the primary current of the high-frequency transformer output by the working mode detection circuit is greater than the first comparison threshold, the load condition of the switching power supply is determined to be light load; when the load condition of the switching power supply is light load, the control terminal of the switching module is connected to the second connection terminal of the switching module, and the matching compensation circuit is a DCM compensation circuit. If the primary current of the high-frequency transformer output by the working mode detection circuit is less than the second comparison threshold, the load condition of the switching power supply is determined to be heavy load; when the load condition of the switching power supply is heavy load, the control terminal of the switching module is connected to the first connection terminal of the switching module, and the matching compensation circuit is a CCM compensation circuit.

7. A switching power supply, characterized in that, include: The control device for a switching power supply as described in any one of claims 1 to 6.

8. A control method for a switching power supply as described in claim 7, characterized in that, include: The primary current of the high-frequency transformer is detected, and the load condition of the switching power supply is determined based on the primary current of the high-frequency transformer in the switching power supply. Based on the load condition of the switching power supply, a corresponding compensation circuit is matched in the preset compensation circuit of different modes, which is denoted as the matching compensation circuit. Based on the output voltage of the high-frequency transformer, voltage compensation is performed to obtain the compensated voltage, which is recorded as the current compensated voltage. Based on the output voltage of the high-frequency transformer, a first error voltage is obtained by comparing it with a preset reference voltage. And, used to use the sum of the first error voltage and the current compensation voltage as the feedback voltage output by the feedback loop; Based on the feedback voltage output by the feedback loop, the conduction time of the switching transistor on the primary side of the high-frequency transformer in the current cycle is controlled to adjust the energy stored in the primary inductance of the high-frequency transformer in the current cycle, thereby controlling the output voltage of the high-frequency transformer.

9. The control method for a switching power supply according to claim 8, characterized in that, in, The different modes of compensation circuits include: CCM compensation circuit and DCM compensation circuit; The primary current of the high-frequency transformer is detected. Based on the primary current of the high-frequency transformer in the switching power supply, the load condition of the switching power supply is determined. According to the load condition of the switching power supply, a corresponding compensation circuit is matched among preset compensation circuits of different modes, denoted as the matching compensation circuit, which includes: The primary current of the high-frequency transformer is sampled to obtain the primary current sampling signal of the high-frequency transformer; The primary current sampling signal of the high-frequency transformer is amplified to obtain the amplified primary current sampling signal of the high-frequency transformer, which is used as the primary current of the high-frequency transformer. If the primary current of the high-frequency transformer output by the working mode detection circuit is greater than the first comparison threshold, the load condition of the switching power supply is determined to be light load; when the load condition of the switching power supply is light load, the control terminal of the switching module is connected to the second connection terminal of the switching module, and the matching compensation circuit is a DCM compensation circuit. If the primary current of the high-frequency transformer output by the working mode detection circuit is less than the second comparison threshold, the load condition of the switching power supply is determined to be heavy load; when the load condition of the switching power supply is heavy load, the control terminal of the switching module is connected to the first connection terminal of the switching module, and the matching compensation circuit is a CCM compensation circuit.

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