A method and system for controlling an isolated multi-output switching power supply

Abstract

The present application discloses an isolated multi-output switching power supply control method, which is based on an isolated multi-output switching power supply. The method includes the following steps: setting a reference voltage for each secondary output circuit; collecting parameters; calculating the primary power device control quantity and the secondary power device control quantity through the parameters and the reference voltage; modulating the primary power device control quantity and the secondary power device control quantity to generate drive signals respectively; adjusting the switching frequency of the primary power device and the phase shift angle of the secondary power device according to the drive signal, so that each secondary output circuit outputs a reference voltage. The present application can avoid the problem of large power supply volume of the single topology solution and the two-stage isolated DC / DC conversion solution, and can solve the problem that the conversion efficiency is affected when there are many conversion paths in the two-stage isolated DC / DC conversion solution, and that all other paths are turned off when the main output is turned off. The present application also relates to an isolated multi-output switching power supply control system.

Description

Technical Field

[0001] The present application relates to the technical field of isolated switching power supplies, and in particular to a control method and system for an isolated multi-output switching power supply. Background Art

[0002] Switching power supplies are widely used in fields involving industrial production, communications, railway locomotives, medical equipment, and military industry. They can achieve multi-channel isolated outputs, which not only saves the number of modules but also ensures the safe and stable operation of the system.

[0003] Switching power supplies primarily achieve isolated multi-output effects through two approaches: independent topology and two-stage isolated DC / DC conversion. In the independent topology approach, each output has an independent topology conversion circuit, equivalent to a combination of multiple power supplies. This takes up a large amount of space on the circuit board, making the layout inflexible, and has disadvantages such as large power supply size, heavy weight, complex circuits, and high cost. In the two-stage isolated DC / DC conversion approach, only one main output exists, and the other outputs are isolated and converted from the main output. This leads to the problem that when the main output is turned off, the other outputs must also be turned off. Furthermore, due to the large number of circuit outputs, the power supply becomes larger and the efficiency of the isolated DC / DC converter is also affected. Summary of the Invention

[0004] The present application provides an isolated multi-output power supply control method and system, which can avoid the problem of large power supply volume in single topology solutions and two-stage isolated DC / DC conversion solutions, and solve the problem that the conversion efficiency is affected when the number of circuit output paths is large, and when the main output is turned off, all other paths are turned off.

[0005] The technical solutions adopted in this application are as follows:

[0006] A method for controlling an isolated multi-output switching power supply, wherein the switching power supply includes a transformer, a primary input circuit, and multiple secondary output circuits. The method includes the following steps:

[0007] Set the reference voltage of each secondary output circuit;

[0008] Acquiring parameters, wherein the parameters include the output voltage and output current of each secondary output circuit;

[0009] The primary side power device control amount and the secondary side power device control amount are calculated by the parameters and the reference voltage;

[0010] Modulating the primary side power device control quantity and the secondary side power device control quantity to generate drive signals respectively;

[0011] The switching frequency of the primary power device and the phase shift angle of the secondary power device are adjusted respectively according to the driving signal, so that each secondary output circuit outputs the reference voltage.

[0012] Furthermore, the control amount of the primary power device and the control amount of the secondary power device are modulated to generate drive signals respectively, including:

[0013] Performing PFM modulation on the primary side power device control variable to generate a primary side input circuit drive signal;

[0014] PS modulation is performed on the control quantity of the secondary side power device to generate driving signals for each secondary side output circuit.

[0015] Furthermore, adjusting the switching frequency of the primary power device and the phase shift angle of the secondary power device according to the driving signal so that each secondary output circuit outputs the reference voltage includes:

[0016] The primary side input circuit driving signal adjusts the switching frequency of the primary side power device through the driving circuit;

[0017] The secondary side output circuit driving signal adjusts the phase shift angle of each secondary side power device through the driving circuit;

[0018] The output voltage of the secondary-side output circuit is adjusted to the reference voltage by adjusting the phase shift angle of the secondary-side power device.

[0019] Furthermore, the secondary side driving signal adjusts the phase difference between the two bridge arms in each secondary side output circuit through the driving circuit;

[0020] The output voltage of the secondary output circuit is adjusted to the reference voltage by adjusting the magnitude of the phase difference.

[0021] Furthermore, calculating the control amount of the primary power device by using the parameters includes the following steps:

[0022] Inputting the output voltages into respective voltage outer loops to obtain output values of respective voltage loops;

[0023] Calculating the sum of the output values of each voltage loop to obtain the inner loop control quantity;

[0024] Calculating output power according to the output voltage and the output current;

[0025] Find the sum of the output powers;

[0026] The sum of the inner loop control variable and the output power is input into the power inner loop to obtain the primary side power device control variable.

[0027] Furthermore, calculating the control amount of the secondary side power device by using the parameter and the reference voltage includes the following steps:

[0028] The output voltage and the reference voltage are input into a voltage single loop to obtain the control value of the secondary side power device.

[0029] The present application also includes an isolated multi-output switching power supply control system, wherein the switching power supply includes a transformer, a primary input circuit, and multiple secondary output circuits, including:

[0030] A setting unit, used to set the reference voltage of each secondary output circuit;

[0031] a parameter acquisition unit, configured to acquire parameters, wherein the parameters include the output voltage and output current of each of the secondary output circuits;

[0032] a calculation unit, configured to calculate a primary-side power device control variable and a secondary-side power device control variable using the parameters and the reference voltage;

[0033] a modulation unit, configured to modulate the control amount of the primary power device and the control amount of the secondary power device to generate drive signals respectively;

[0034] The regulating unit is used to regulate the switching frequency of the primary power device and the phase shift angle of the secondary power device according to the driving signal, so that each secondary output circuit outputs the reference voltage.

[0035] The beneficial effects of adopting the technical solution of this application are as follows:

[0036] The present application adopts the method of setting multiple secondary output circuits on the secondary side of the transformer and setting corresponding control methods to solve the problems of excessive power supply volume, high cost and complex circuits; in the present application, a dual closed-loop control method is adopted for the primary side of the transformer, in which the outer loop is a voltage loop and the inner loop is a power loop; for the secondary side of the transformer, since there are multiple secondary output circuits on the secondary side of the transformer, each secondary output circuit corresponds to a voltage loop, so the secondary side of the transformer adopts a voltage single closed-loop control method, and the inner loop control quantity (i.e., the sum of all voltage loop output values) and the inner loop controlled quantity (i.e., the sum of all output powers) are calculated by the above control method. Based on the above control method and calculation results, the primary side of the transformer adopts PFM modulation method, and the secondary side of the transformer adopts PS modulation method to modulate the primary side power device control quantity and the secondary side power device control quantity, and finally realizes the ability to independently control each secondary side output circuit, solves the problem of mutual influence between outputs, and also reduces the size of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0038] Figure 1 This is a principle block diagram of a method for controlling an isolated multi-output switching power supply provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to enable people in this technical field to better understand the technical solutions in the embodiments of the present application, and to make the above-mentioned purposes, features and advantages of the embodiments of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application are further described in detail below with reference to the accompanying drawings.

[0040] See also Figure 1 , which is a principle block diagram of an isolated multi-output switching power supply control method provided in an embodiment of the present application.

[0041] The present application provides an isolated multi-output switching power supply control method applied to an isolated multi-output switching power supply. Figure 1 As shown, the isolated multi-output switching power supply includes an input circuit, an output circuit and a transformer. The primary input circuit is composed of a combination of multiple primary power devices, the secondary output circuit is composed of a combination of multiple secondary power devices, and the transformer is composed of a primary winding connected to the input circuit and a secondary winding connected to the output circuit.

[0042] In this embodiment, the isolated multi-output switching power supply is isolated by a transformer, and the primary winding of the transformer is connected to the primary input circuit. The power output of the primary side can be controlled by controlling the on and off of the primary power device. The secondary side of the transformer is connected to multiple secondary windings, and multiple secondary output circuits are correspondingly connected through the secondary windings, and each output circuit can be isolated from each other. The primary input circuit is composed of a combination of multiple primary power devices, and the secondary output circuit is composed of a combination of multiple secondary power devices. The output voltage of each output circuit is controlled by controlling the power device. Based on this switching power supply, the isolated multi-output switching power supply control method of the present application has the following steps:

[0043] Step S01 sets the reference voltage U of each secondary output circuit. ref1 、U ref2 ,…,U refn , n is the number of secondary side output circuits.

[0044] Step S02 samples the parameters of the input circuit and the output circuit, wherein the parameters include the input voltage U of the primary input circuit. in And input current I in(used for monitoring circuit), the output voltage U of each secondary output circuit o1 、U o2 ,…,U on And the output current I o1 , I o2 ,…,I on .

[0045] Step S03 calculates the primary side power device control amount and the secondary side power device control amount through the parameters and the reference voltage.

[0046] In this embodiment, the primary input circuit adopts a dual closed-loop control method. Based on the dual closed-loop control method, the control amount of the primary power device is calculated. Specifically, the outer loop in the dual closed-loop control is a voltage loop. Since there are multiple secondary output circuits, each secondary output circuit corresponds to a voltage loop. The output voltage is input into each voltage outer loop in turn. After calculation, the voltage loop output value PI of each voltage loop is obtained. out1 ,PI out2 ,…,PI outn ; Then output the value PI of each voltage loop out1 ,PI out2 ,…,PI outn The sum is taken to obtain the inner loop control quantity; in the dual closed-loop control, the inner loop is the power loop. The output power is calculated based on the output voltage and output current of each secondary output circuit, and then the sum of the output powers is calculated. Finally, the sum of the inner loop control quantity and the output power is input into the power inner loop. After calculation, the control quantity of the primary power device is obtained.

[0047] The secondary side of the transformer adopts a voltage single-loop control method. Based on the voltage single-loop control method, the control amount of the secondary side power device is calculated. Specifically: since there are multiple secondary side output circuits, in order to achieve independent control of each secondary side output circuit, the output voltage of the secondary side output circuit and the set reference voltage are input into the voltage single loop. After calculation, the control amount of the secondary side power device is obtained.

[0048] Because the transformer's primary side uses a dual closed-loop control scheme, with the outer loop being a voltage loop and each secondary output circuit corresponding to a voltage loop, the inner loop's control variable is the sum of all outer loop output values. When the total power output from the primary side to the secondary side is insufficient or excessive, the primary side's control variable changes to adjust its output. Therefore, the inner loop is a power loop, and the primary side outputs corresponding power to the secondary side. The demand for each secondary side circuit is distributed based on the secondary side's control variable. The method for the primary side to output corresponding power to the secondary side and for each secondary side circuit to adjust its output based on the control variable of the secondary power device is described in steps S04 and S05.

[0049] Step S04 modulates the control amount of the primary side power device and the control amount of the secondary side power device to generate driving signals respectively.

[0050] The primary side adopts PFM (Pulse Frequency Modulation) modulation mode, which can adjust the primary side output power by adjusting the switching frequency of the primary side power device. Therefore, the primary side power device control amount obtained in step S03 is modulated by PFM modulation to generate a primary side drive signal.

[0051] Furthermore, the secondary power device control variable obtained in step S03 is modulated using PS (Phase Shift) modulation to generate secondary drive signals for each secondary output circuit. Because the primary step-up and step-down voltage is handled by the transformer, the step-up and step-down ratio of the secondary output circuit is not large. Therefore, this embodiment uses PS modulation to modulate the outputs of each secondary output circuit.

[0052] Step S05 adjusts the switching frequency of the primary power device and the phase shift angle of the secondary power device according to the driving signal, so that each secondary output circuit outputs a reference voltage.

[0053] In this embodiment, when the secondary output circuit is unloaded, the input circuit outputting a relatively low power level can satisfy the requirement that the output voltage of the secondary output circuit be equal to the reference voltage. However, when the secondary output circuit is loaded, if the input circuit does not adjust the power level, the output voltage of the secondary output circuit will be lower than the reference voltage at the same power level, making it difficult to ensure normal operation of the load. Therefore, when the load on the secondary output circuit increases or decreases, the power output of the input circuit must be increased or decreased to meet the requirements of the secondary load, and the output voltage of the secondary output circuit must be adjusted to be equal to the set reference voltage.

[0054] This embodiment provides a method for adjusting the output power of the input circuit and adjusting the output voltage of the secondary side, specifically:

[0055] The primary-side drive signal adjusts the switching frequency of the primary-side power devices through the driver circuit, thereby ensuring the primary-side output power is proportional. Simultaneously, the secondary-side drive signal adjusts the phase shift angle of each secondary-side power device through the driver circuit, thereby adjusting the output voltage of the secondary-side output circuit to the reference voltage. When the secondary-side output circuit is connected to a load, the primary-side output power is sufficient to supply the secondary-side load for normal operation while also ensuring that the output voltage is equal to the reference voltage.

[0056] The present application adopts the method of setting multiple secondary output circuits on the secondary side of the transformer and designing corresponding control methods to solve the problems of excessive power supply volume, high cost and complex circuits. The specific method is: for the primary side of the transformer, a dual closed-loop control method with an outer loop as a voltage loop and an inner loop as a power loop is adopted; for the secondary side of the transformer, since there are multiple secondary output circuits on the secondary side of the transformer, each secondary output circuit corresponds to a voltage loop, so the secondary side of the transformer adopts a voltage single closed-loop control method, and the inner loop control quantity calculated by the above control method is the sum of all outer loops (that is, the sum of all voltage loop output values), and the inner loop controlled quantity is the sum of all output powers. Based on the above control method and calculation results, the primary side of the transformer adopts PFM modulation method, and the secondary side of the transformer adopts PS modulation method to modulate the control quantity of the primary power device and the control quantity of the secondary power device, and finally realizes independent control of each secondary output circuit, solves the problem of mutual influence between outputs, and also reduces the volume of the power supply.

[0057] The present application also provides an isolated multi-output switching power supply control system, wherein the switching power supply includes a transformer, a primary input circuit, and multiple secondary output circuits, including:

[0058] A setting unit, used to set the reference voltage of each secondary output circuit;

[0059] A parameter acquisition unit, configured to acquire parameters, wherein the parameters include the output voltage and output current of each secondary output circuit;

[0060] A calculation unit, configured to calculate a primary-side power device control quantity and a secondary-side power device control quantity through parameters and a reference voltage;

[0061] A modulation unit, used to modulate the control amount of the primary side power device and the control amount of the secondary side power device to generate drive signals respectively;

[0062] The regulating unit is used to adjust the switching frequency of the primary power device and the phase shift angle of the secondary power device according to the driving signal, so that each secondary output circuit outputs a reference voltage.

[0063] Similar parts between the embodiments provided in this application can be referenced to each other. The specific implementation methods provided above are only a few examples under the overall concept of this application and do not constitute a limitation on the scope of protection of this application. For those skilled in the art, any other implementation methods expanded based on the scheme of this application without expending creative work shall fall within the scope of protection of this application.

Claims

1. A method for controlling an isolated multi-output switching power supply, wherein the switching power supply comprises a transformer, a primary input circuit, and multiple secondary output circuits, characterized in that: The method comprises the following steps: Set the reference voltage of each secondary output circuit; Acquiring parameters, wherein the parameters include the output voltage and output current of each secondary output circuit; The primary side power device control amount and the secondary side power device control amount are calculated by the parameters and the reference voltage; Calculating the control amount of the primary power device by using the parameters includes the following steps: Inputting the output voltages into respective voltage outer loops to obtain output values of respective voltage loops; Calculating the sum of the output values of each voltage loop to obtain the inner loop control quantity; Calculating output power according to the output voltage and the output current; Find the sum of the output powers; Inputting the sum of the inner loop control variable and the output power into the power inner loop to obtain the primary side power device control variable; Modulating the primary side power device control quantity and the secondary side power device control quantity to generate drive signals respectively; The switching frequency of the primary power device and the phase shift angle of the secondary power device are adjusted respectively according to the driving signal, so that each secondary output circuit outputs the reference voltage.

2. The isolated multi-output switching power supply control method according to claim 1, characterized in that: Modulating the primary power device control quantity and the secondary power device control quantity to generate drive signals respectively includes: Performing PFM modulation on the primary side power device control variable to generate a primary side input circuit drive signal; PS modulation is performed on the control quantity of the secondary side power device to generate driving signals for each secondary side output circuit.

3. The isolated multi-output switching power supply control method according to claim 2, characterized in that: Adjusting the switching frequency of the primary power device and the phase shift angle of the secondary power device according to the driving signal so that each secondary output circuit outputs the reference voltage includes: The primary side input circuit driving signal adjusts the switching frequency of the primary side power device through the driving circuit; The secondary side output circuit driving signal adjusts the phase shift angle of each secondary side power device through the driving circuit; The output voltage of the secondary-side output circuit is adjusted to the reference voltage by adjusting the phase shift angle of the secondary-side power device.

4. The isolated multi-output switching power supply control method according to claim 3, characterized in that: The secondary output circuit driving signal adjusts the phase difference between the two bridge arms in each secondary output circuit through the driving circuit; The output voltage of the secondary output circuit is adjusted to the reference voltage by adjusting the magnitude of the phase difference.

5. The isolated multi-output switching power supply control method according to claim 1, characterized in that: Calculating the control amount of the secondary side power device by using the parameter and the reference voltage includes the following steps: The output voltage and the reference voltage are input into a voltage single loop to obtain the control value of the secondary side power device.

6. An isolated multi-output switching power supply control system, wherein the switching power supply comprises a transformer, a primary input circuit and multiple secondary output circuits, characterized in that: include: A setting unit, used to set the reference voltage of each secondary output circuit; a parameter acquisition unit, configured to acquire parameters, wherein the parameters include the output voltage and output current of each of the secondary output circuits; a calculation unit, configured to calculate a primary-side power device control variable and a secondary-side power device control variable using the parameters and the reference voltage; Calculating the control amount of the primary power device by using the parameters includes the following steps: Inputting the output voltages into respective voltage outer loops to obtain output values of respective voltage loops; Calculating the sum of the output values of each voltage loop to obtain the inner loop control quantity; Calculating output power according to the output voltage and the output current; Find the sum of the output powers; Inputting the sum of the inner loop control variable and the output power into the power inner loop to obtain the primary side power device control variable; a modulation unit, configured to modulate the control amount of the primary power device and the control amount of the secondary power device to generate drive signals respectively; The regulating unit is used to regulate the switching frequency of the primary power device and the phase shift angle of the secondary power device according to the driving signal, so that each secondary output circuit outputs the reference voltage.

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