DCDC loop parallel control method

Abstract

The application provides a DCDC loop parallel control method applied to a DCDC loop parallel control system, the DCDC loop parallel control system comprising a preset number of loops; the preset number of loops are in parallel, and the preset number of loops is equal to the number of controlled electrical signals, and each loop corresponds to control of a controlled electrical signal; the DCDC loop parallel control method comprises the following steps: inputting real-time errors of each controlled electrical signal into corresponding loops respectively; performing normalization processing on output values of each loop respectively to obtain a corresponding switch duty cycle of each loop; and controlling the conduction time of a DCDC switch device based on the corresponding switch duty cycle of each loop; the DCDC control mode of the application adopts multi-loop parallel connection, can ensure that multiple electrical signals such as DCDC input and output voltages and currents meet the requirements at the same time, avoids triggering of faults to cause damage of equipment or system shutdown, avoids multi-stage series connection of loops, reduces the design difficulty, shortens the research and development cycle, and improves the operation stability of the DCDC.

Description

Technical Field

[0001] This invention relates to the field of electrical engineering, and more particularly to DC-DC conversion technology, especially a parallel control method for DC-DC loops. Background Technology

[0002] DC-DC converters are widely used in the energy sector. Both their input and output are DC, but their voltage levels and current capabilities differ. The core function of DC-DC converters is usually to regulate voltage, current, or power output. They generally employ closed-loop feedback control to achieve stable output of the controlled electrical quantity. DC-DC converters have diverse application scenarios, and the controlled electrical signal is not unique, including input voltage, input current, input power, output voltage, output current, and output power.

[0003] Existing DC-DC converters often use the current or voltage at one end as the controlled parameter, while other electrical signals are only used as protection inputs. The DC-DC power is only cut off or reduced when the protection threshold is reached. However, the controller has poor stability and is prone to triggering protection, causing shutdowns and equipment failures.

[0004] Another approach uses a multi-stage closed-loop method, such as using the output of the voltage loop as the input of the current loop, which can simultaneously control the voltage and current to not exceed the limits. However, since the loops are connected in series, the output of the outer loop is used as the input of the inner loop. When the parameters of one loop are adjusted, the response characteristics of the other loop will also be affected. Therefore, it is necessary to perform parameter tuning on the series loops at the same time, which increases the difficulty of parameter tuning. Especially when the number of controlled electrical signals increases, it will increase the control complexity and reduce the system stability. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a parallel control method for DC-DC loops to solve the problems of increased system control complexity and reduced system stability caused by the need for multiple electrical signals to be controlled simultaneously in existing DC-DC systems.

[0006] To achieve the above and other related objectives, this invention provides a DC-DC loop parallel control method, applied to a DC-DC loop parallel control system. The DC-DC loop parallel control system includes a preset number of loops; the preset number of loops are connected in parallel, and the number of preset loops is equal to the number of controlled electrical signals. Each loop controls one controlled electrical signal. The DC-DC loop parallel control method includes the following steps: inputting the real-time error of each controlled electrical signal to the corresponding loop; normalizing the output value of each loop to obtain the switching duty cycle corresponding to each loop; and controlling the conduction time of the DC-DC switching device based on the switching duty cycle corresponding to each loop.

[0007] In one embodiment of the present invention, controlling the conduction time of the DC-DC switching device based on the duty cycle of the switch corresponding to each loop includes the following steps: selecting the minimum value from the duty cycles of the switches corresponding to each loop; and controlling the conduction time of the DC-DC switching device according to the minimum value.

[0008] In one embodiment of the present invention, at any given time, only the loop with the smallest corresponding switch duty cycle is in an active state, while the other loops are in an inactive state. The method further includes the following steps: setting a base value and an upper limit value for the closed-loop output of each loop; when the loop changes from an active state to an inactive state, resetting the integral portion of the loop, and setting the base value and upper limit value of the loop to be the switch duty cycle of the loop in the new active state plus a preset duty cycle index value; when the loop changes from an inactive state to an active state, the switch duty cycle of the loop changes continuously based on the switch duty cycle of the loop in the previous active state.

[0009] In one embodiment of the present invention, the adjustment calculation formula for the loop is:

[0010]

[0011] Where y(k) represents the output value of the loop at time k; u(k) represents the input value of the loop at time k; K p K represents the proportionality coefficient. i T represents the integral coefficient; s The discrete period is represented by u(i); u(i) represents the input value of the loop at time i; i ranges from 1 to k; when y(k) is greater than the upper limit value corresponding to the loop, the output value of the loop is the upper limit value, and the integration accumulation stops.

[0012] In one embodiment of the present invention, before inputting the real-time error of each controlled electrical signal to the corresponding loop, the method further includes the following steps: obtaining the actual value of each controlled electrical signal; subtracting the actual value of each controlled electrical signal from the corresponding preset value to obtain the real-time error of each controlled electrical signal.

[0013] In one embodiment of the present invention, the loop adopts PI or PID digital control.

[0014] As described above, the DC-DC loop parallel control method of the present invention has the following beneficial effects:

[0015] (1) Compared with the prior art, the present invention adopts a multi-loop parallel DCDC control method, which can ensure that multiple electrical signals such as DCDC input and output voltage and current meet the requirements at the same time, avoid triggering faults that cause equipment damage or system shutdown, avoid multi-level series connection of loops, reduce design difficulty, shorten the R&D cycle, and improve the DCDC operation stability.

[0016] (2) The rapid switching of multiple loops of DCDC in this invention can improve the switching speed of bidirectional control of DCDC, expand the application scenarios of DCDC, reduce the application of voltage sources, and reduce the complexity of the entire system. Attached Figure Description

[0017] Figure 1 The diagram shown illustrates the working principle of the DC-DC loop parallel control system of the present invention in one embodiment.

[0018] Figure 2 The flowchart shown is an embodiment of the DC-DC loop parallel control method of the present invention.

[0019] Figure 3 The flowchart shown is a flowchart of another embodiment of the DC-DC loop parallel control method of the present invention.

[0020] Figure 4 The flowchart shown is a flowchart of one embodiment of the present invention, which controls the on-time of a DC-DC switching device based on the duty cycle of the switch corresponding to each loop. Detailed Implementation

[0021] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0022] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0023] Compared with the prior art, the parallel control method of DC-DC loops in this invention adopts a multi-loop parallel DC-DC control mode, which can ensure that multiple electrical signals such as DC-DC input and output voltage and current meet the requirements simultaneously, avoiding equipment damage or system shutdown caused by triggering faults. It also avoids multi-level series connection of loops, reduces design difficulty, shortens the development cycle, and improves the operational stability of DC-DC. The rapid switching of multiple DC-DC loops in this invention can improve the switching speed of DC-DC bidirectional control, expand the application scenarios of DC-DC, reduce the use of voltage sources, and reduce the overall system complexity.

[0024] like Figure 1 As shown, in one embodiment, the DC-DC loop parallel control method of the present invention is applied to a DC-DC loop parallel control system.

[0025] Specifically, the DC-DC loop parallel control system includes a preset number of loops; the preset number of loops are connected in parallel, and the number of preset loops is equal to the number of controlled electrical signals, with each loop corresponding to control one controlled electrical signal.

[0026] It should be noted that this loop is either a current loop control circuit or a voltage loop control circuit; specifically, the number of parallel loops is designed according to the number of electrical signals to be controlled in actual need.

[0027] Furthermore, the controlled electrical signal typically includes any of the following signals: voltage, current, power, etc.; in addition, the controlled electrical signal can be a signal on the input side of the DC-DC converter or a signal on the output side; through loop switching, the energy direction of the DC-DC converter can be flexibly and quickly switched.

[0028] like Figure 2 As shown, in one embodiment, the DC-DC loop parallel control method includes the following steps:

[0029] Step S1: Input the real-time error of each controlled electrical signal into the corresponding loop.

[0030] like Figure 3 As shown, in one embodiment, before inputting the real-time error of each controlled electrical signal to the corresponding loop, the method further includes the following steps:

[0031] Step S4: Obtain the actual value of each controlled electrical signal.

[0032] Specifically, the actual value of the corresponding controlled electrical signal is obtained through a voltage acquisition circuit or a current acquisition circuit.

[0033] Step S5: Subtract the actual value of each controlled electrical signal from the corresponding preset value to obtain the real-time error of each controlled electrical signal.

[0034] It should be noted that the preset value corresponding to each controlled electrical signal may be the same or different. The specific value set is not a limitation of the present invention. In practical applications, it can be set according to the specific application scenario.

[0035] Furthermore, this preset value can be a fixed value, or it can change over time through communication functions during the operation of the DC-DC converter.

[0036] Step S2: Normalize the output value of each loop to obtain the switch duty cycle corresponding to each loop.

[0037] Specifically, the output value of each loop is normalized to between 0 and 1 to serve as the duty cycle of the switch for each loop.

[0038] Step S3: Control the conduction time of the DC-DC switching device based on the duty cycle of the switch corresponding to each loop.

[0039] like Figure 4 As shown, in one embodiment, controlling the on-time of the DC-DC switching device based on the duty cycle of the switch corresponding to each loop includes the following steps:

[0040] Step S31: Select the minimum value from the switch duty cycles corresponding to each loop.

[0041] Step S32: Control the conduction time of the DC-DC switching device according to the minimum value.

[0042] It should be noted that by utilizing this minimum value, the value of the controlled electrical signal can be changed, thereby reducing the error of the controlled object and realizing closed-loop control.

[0043] In one embodiment, at any given time, only the loop with the smallest corresponding switch duty cycle is in an active state, while the other loops are in an inactive state.

[0044] In one embodiment, the method further includes the step of setting a base value and an upper limit value for the closed-loop output of each loop.

[0045] It should be noted that the base value is the initial value of the loop output; the upper limit value is the maximum value of the loop output.

[0046] It should be noted that when the loop state changes from an active state to an inactive state, the integral part of the loop is reset, and the base value and upper limit value of the loop are the switch duty cycle corresponding to the new active state plus the preset duty cycle scale value; when the loop state changes from an inactive state to an active state, the switch duty cycle corresponding to the loop changes continuously based on the switch duty cycle corresponding to the previous active state, and the adjustment of the active state loop can quickly stabilize to the target value (the target value is the preset value corresponding to the controlled electrical signal controlled by the active state loop).

[0047] It should be noted that the preset duty cycle value is pre-set, and its specific setting is not a limitation of the present invention. In practical applications, it can be set according to the specific application scenario.

[0048] In one embodiment, the adjustment calculation formula for the loop is:

[0049]

[0050] Where y(k) represents the output value of the loop at time k; u(k) represents the input value of the loop at time k; K p K represents the proportionality coefficient. i T represents the integral coefficient; s The discrete period is represented by u(i); u(i) represents the input value of the loop at time i; i ranges from 1 to k.

[0051] It should be noted that when y(k) is greater than the upper limit value corresponding to the loop, the output value of the loop is the upper limit value, and the integration accumulation stops.

[0052] In one embodiment, the loop employs PI or PID digital control.

[0053] It should be noted that this loop is not limited to using PI or PID digital control methods; other digital control methods can also be used, and the control parameters are independent of each other.

[0054] Furthermore, the DC-DC loop parallel control method of the present invention does not limit the DC-DC topology.

[0055] It should be noted that this invention employs a parallel loop configuration, solving the problem of simultaneously controlling multiple electrical signals of the DC-DC converter. This avoids increasing system complexity, improves system stability, and ensures that multiple electrical signals, such as DC-DC input and output voltage and current, simultaneously meet requirements, preventing equipment damage or system shutdown caused by triggering faults. Each loop controls one electrical signal, and the simultaneous parallel operation of multiple loops ensures that all signals do not exceed the specified values. An association mechanism is designed between multiple parallel loops, allowing for rapid switching of effective loops when one or more controlled target values ​​change, preventing signal over-limit during dynamic adjustment. This enables rapid switching of multiple electrical loops, facilitating applications of rapid switching of DC-DC energy transmission direction, improving the switching speed of bidirectional DC-DC control, expanding DC-DC application scenarios, reducing the use of voltage sources, and lowering the overall system complexity.

[0056] It should be noted that the protection scope of the DC-DC loop parallel control method described in this invention is not limited to the execution order of the steps listed in this embodiment. Any solution implemented by adding, subtracting, or replacing steps in the prior art based on the principles of this invention is included within the protection scope of this invention.

[0057] The following specific embodiments will further explain the parallel control method of DC-DC loops of the present invention.

[0058] In one embodiment, taking a bidirectional DC-DC converter as an example, the forward direction is Boost and the reverse direction is Buck. According to the forward definition, the power inflow side is the input side and the power outflow side is the output side. When the DC-DC converter's input current Ii, input power Pi, and output voltage Uo, a total of three electrical signals, must be controlled to not exceed the corresponding set values ​​Iiset, Piset, and Uoset, three parallel control loops are designed, with each loop controlling one electrical signal.

[0059] Taking the input current loop as an example, the actual input current Ii is collected by the current sensor, the input current error Iierr = Iiset - Ii is calculated, Iierr is used as the input of the current loop, and the output of the current loop is obtained after PI regulation. The PI output value is normalized to between 0 and 1, which can be used as the switching duty cycle DutyIi.

[0060] PI adjustment calculation formula: Where y(k) represents the output value of the loop at time k; u(k) represents the input value of the loop at time k; K p K represents the proportionality coefficient. i T represents the integral coefficient; sThe discrete period is represented by u(i); u(i) represents the input value of the loop at time i; i ranges from 1 to k; an upper limit value is set for the loop output. When y(k) is greater than the upper limit value, the output is based on the upper limit value, and the integration accumulation is stopped.

[0061] Similarly, by collecting the DC-DC input voltage Ui and output voltage Uo, and multiplying the input voltage by the input current to obtain the actual input power Pi, the PI regulation outputs of the other two loops can be obtained as DutyPi and DutyUo, respectively.

[0062] The set value of each electrical signal (corresponding to the preset value mentioned above) can be a fixed value, or it can change over time through the communication function during the operation of the DC-DC converter.

[0063] Before the three loops operate, the difference between the three actual electrical signals and the corresponding set values ​​is calculated to obtain the real-time errors of the three controlled electrical signals. Then, the three errors are input to the three loops respectively, and each loop obtains three outputs through a digital control algorithm, which are normalized to between 0 and 1, and used as three duty cycle signals.

[0064] Within each calculation cycle, the minimum of the three duty cycle signals is taken as DutyT, which is used to control the DC-DC power switch. Assuming the effective state loop with the smallest duty cycle at time T is the input current loop, then the input power loop and output voltage loop are in an invalid state. At time T+1, the integrators of the input power loop and output voltage loop are reset, i.e., the integrators... Set it to 0, restart the integration, and set the initial and upper limits of the two loops to DutyT+Dutymin, where Dutymin is the minimum duty cycle division value of the system (corresponding to the preset duty cycle division value mentioned above).

[0065] If, at time T+n, the output voltage target value or sampled value changes, and the output signal of the output voltage loop becomes the minimum among the three loops, then the effective loop switches from the input current loop to the output voltage loop. DutyT+n is the closed-loop result of the output voltage loop. The DC-DC converter quickly adjusts the output voltage to the target value through the output voltage loop.

[0066] It should be noted that by controlling the switching from the input current loop to the output voltage loop, the forward to reverse switching of DC-DC power can be achieved.

[0067] The process of switching other loops is the same, so it will not be described in detail here.

[0068] In summary, compared with the prior art, the parallel control method of DC-DC loops of the present invention adopts a multi-loop parallel DC-DC control mode, which can ensure that multiple electrical signals such as DC-DC input and output voltage and current meet the requirements simultaneously, avoiding equipment damage or system shutdown caused by triggering faults. It also avoids multi-level series connection of loops, reduces design difficulty, shortens the R&D cycle, and improves the operational stability of DC-DC. The rapid switching of multiple DC-DC loops in the present invention can improve the switching speed of DC-DC bidirectional control, expand the application scenarios of DC-DC, reduce the use of voltage sources, and reduce the complexity of the entire system. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0069] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A DC-DC loop parallel control method, applied to a DC-DC loop parallel control system, characterized in that, The DC-DC loop parallel control system includes a preset number of loops; the preset number of loops are connected in parallel, and the number of preset loops is equal to the number of controlled electrical signals, with each loop corresponding to control one controlled electrical signal; the DC-DC loop parallel control method includes the following steps: The real-time error of each controlled electrical signal is input to the corresponding loop. The output value of each loop is normalized to obtain the switch duty cycle corresponding to each loop. The on-time of the DC-DC switching device is controlled based on the duty cycle of the switch corresponding to each loop. At any given moment, among all the loops, only the loop with the smallest corresponding switch duty cycle is in an active state, while the other loops are in an inactive state. The method further includes the following steps: Set the base value and upper limit value of the closed-loop output of each loop; When the loop state changes from an active state to an inactive state, the integral part of the loop is reset, and the base value and upper limit value of the loop are both the switch duty cycle of the loop in the new active state plus the preset duty cycle value. When the state of the loop changes from an invalid state to an active state, the duty cycle of the switch corresponding to the loop changes continuously based on the duty cycle of the switch corresponding to the loop in the previous active state. The adjustment calculation formula for the loop is: ； in, This represents the output value of the loop at time k; This represents the input value of the loop at time k; Indicates the proportionality coefficient; Indicates the integral coefficient; Indicates discrete period; This represents the input value of the loop at time i; i ranges from 1 to k. when When the value exceeds the upper limit value corresponding to the loop, the output value of the loop is the upper limit value, and the integration accumulation stops.

2. The DC-DC loop parallel control method according to claim 1, characterized in that, The control of the conduction time of the DC-DC switching device based on the duty cycle of the switch corresponding to each loop includes the following steps: Select the minimum value from the switch duty cycle corresponding to each of the aforementioned loops; The conduction time of the DC-DC switching device is controlled according to the minimum value.

3. The DC-DC loop parallel control method according to claim 1, characterized in that, Before inputting the real-time error of each controlled electrical signal to the corresponding loop, the method further includes the following steps: Obtain the actual value of each of the controlled electrical signals; The actual value of each controlled electrical signal is subtracted from the corresponding preset value to obtain the real-time error of each controlled electrical signal.

4. The DC-DC loop parallel control method according to claim 1, characterized in that, The loop uses PI or PID digital control.

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