Double-closed-loop power control method and system based on positive current feedback

Abstract

The invention relates to the technical field of power electronic power control, and discloses a double-closed-loop power control method and system based on positive current feedback, and the system comprises a positive current detection module, a negative current detection module, a voltage detection module, an inner loop controller, an outer loop controller, a PID controller, and a power conversion module. Through deep fusion of an inner-loop current control loop and an outer-loop voltage control loop, high-performance adjustment of a power system is realized, control robustness is improved, and control is performed by directly associating positive current of a power output end and taking the positive current as a feedback signal, so that a foundation is laid for subsequent power control, and the power control efficiency is improved. A PID control strategy and a PI control strategy are respectively adopted, so that the response speed and precision can be effectively improved, and the requirements of high-requirement scenes are met.

Description

Technical Field

[0001] This invention relates to the field of power electronic power control technology, and more specifically to a dual closed-loop power control method and system based on positive current feedback. Background Technology

[0002] With the rapid development of new energy technologies, the accuracy, dynamic response, and anti-interference capability of power control systems have become key indicators. Traditional power control often adopts single closed-loop control, such as voltage loop or current loop, but it has some shortcomings. Single-loop control has insufficient dynamic performance. It can not respond quickly to load changes or input disturbances by only relying on output voltage or total current feedback, which can easily lead to output power fluctuations. The control effect is often difficult to achieve the ideal state, and it has certain limitations.

[0003] Therefore, existing technologies have proposed dual closed-loop control schemes, such as current loop plus voltage loop. However, in existing technologies, the feedback quantity of the current loop is usually selected as the negative current or bus current, which is not directly related to the positive current of the power output terminal. Furthermore, the control parameters are not optimized for the characteristics of the positive current, resulting in dynamic response and accuracy still failing to meet the requirements of high-demand scenarios.

[0004] In view of this, the present invention proposes a dual closed-loop power control method and system based on positive current feedback. By directly acquiring the positive current as the current loop feedback quantity, and through the deep integration of the inner current loop and the outer voltage loop, high-performance regulation of the power system is achieved, and control robustness is improved, so as to solve the above problems. Summary of the Invention

[0005] To overcome the aforementioned deficiencies in the prior art, this invention provides a dual closed-loop power control method and system based on positive current feedback. Through the synergistic effect of inner-loop PID current control and outer-loop PI voltage control, the power system achieves rapid dynamic response, high-precision steady-state regulation, and strong anti-interference capability, thereby solving the problems existing in the background art. As a key parameter that directly reflects the working state of power devices, the positive current feedback signal can more accurately capture the dynamic characteristics of the system.

[0006] This invention provides the following technical solution: a dual closed-loop power control method based on positive current feedback, comprising the following steps:

[0007] Step 1: Establish a dual closed-loop control structure with positive current feedback. The dual closed-loop control structure includes an inner current control loop and an outer voltage control loop. The inner current control loop uses the positive current as the feedback signal, and the outer voltage control loop uses the output voltage as the feedback signal.

[0008] Step 2: In the inner current control loop, based on the positive current feedback signal, a proportional-integral-derivative control strategy is used for current control.

[0009] Step 3: In the outer voltage control loop, voltage control is performed using a proportional-integral control strategy based on the difference between the actual output voltage value and the set value.

[0010] Step 4: Add the output of the inner current control loop to the output of the outer voltage control loop to obtain the total control output;

[0011] Step 5: Drive the power switching devices based on the total control output to achieve power control.

[0012] Preferably, the inner current control loop acquires the actual value of the positive current and outputs a voltage command to control the current in the power system; the outer voltage control loop acquires the actual value of the output voltage and compares it with a preset voltage reference value to generate a voltage loop error signal, and outputs a voltage control signal to control the output voltage of the power system.

[0013] Preferably, in step two, the current control using a proportional-integral-derivative control strategy is expressed as follows:

[0014] Among them, u pI (t) represents the output of the inner loop current control loop at time t, K pI K represents the proportional gain of the inner current control loop. iI K represents the reciprocal of the integral time constant of the inner loop current control loop. dI e represents the differential time constant of the inner loop current control loop. I (t) represents the current error at time t.

[0015] Preferably, the e I (t) is represented as:

[0016] e I (t)=I * (t)-I r (t), where I * (t) represents the positive current setting value of the inner loop current control loop at time t, I r (t) represents the actual value of the positive current of the inner loop current control loop at time t.

[0017] Preferably, in step three, the voltage control based on the difference between the output voltage and the given voltage using a proportional-integral control strategy is expressed as follows:

[0018] Among them, u pV (t) represents the output of the outer loop voltage control loop at time t, K pV K represents the proportional gain of the outer loop voltage control loop. iV e represents the reciprocal of the integral time constant of the outer loop voltage control loop.V (t) represents the voltage error at time t.

[0019] Preferably, the e V (t) is represented as:

[0020] e V (t)=U * (t)-U r (t), where U * (t) represents the output voltage setpoint of the outer loop voltage control loop at time t, U r (t) represents the actual output voltage of the outer loop voltage control loop at time t.

[0021] Preferably, in step four, the output of the inner current control loop is added to the output of the outer voltage control loop to obtain the total control output, which is expressed as follows:

[0022] u all (t)=u pI (t)+u pV (t); where u all (t) represents the total control output at time t, which is used as the drive command for the power device after being limited.

[0023] Preferably, in step five, the driving command is converted into a switching signal using a pulse width modulation algorithm to drive the power device, thereby achieving power control. The energy conversion control of the power system is achieved by adjusting the duty cycle of the device.

[0024] A dual closed-loop power control system based on positive current feedback includes a positive current detection module, a negative current detection module, a voltage detection module, an inner loop controller, an outer loop controller, a PID controller, and a power conversion module.

[0025] The positive current detection module is used to detect the positive current.

[0026] The negative electrode current detection module is used to detect the negative electrode current;

[0027] The voltage detection module is used to detect the input voltage and the output voltage;

[0028] The inner loop controller uses the positive current as a feedback signal and outputs a voltage command to control the current in the power system.

[0029] The outer loop controller is used to collect the actual value of the output voltage and compare it with the preset voltage reference value to generate a voltage loop error signal. The output voltage control signal is used to control the output voltage of the power system.

[0030] The PID controller uses a proportional-integral-derivative control strategy for current control based on the positive current feedback signal; and uses a proportional-integral control strategy for voltage control based on the difference between the actual output voltage value and the set value.

[0031] The power conversion module adds the output of the inner loop controller to the output of the outer loop controller to obtain the total control output; based on the total control output, the power switching device is driven to achieve power control.

[0032] The technical effects and advantages of this invention are as follows:

[0033] This invention includes a fifth step, which facilitates the deep integration of the inner current control loop and the outer voltage control loop, enabling high-performance regulation of the power system and improving control robustness. Furthermore, the third step directly correlates with the positive current of the power output terminal, using the positive current as a feedback signal for control, thus laying the foundation for subsequent power control. In addition, the third and fourth steps respectively employ PID control strategy and PI control strategy, which can effectively improve response speed and accuracy, meeting the needs of high-requirement scenarios. Attached Figure Description

[0034] Figure 1 This is a flowchart of the dual closed-loop power control method based on positive current feedback according to the present invention.

[0035] Figure 2 This is a structural diagram of the dual closed-loop power control system based on positive current feedback according to the present invention. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In addition, the forms of the various structures described in the following embodiments are merely illustrative. The dual closed-loop power control method and system based on positive current feedback involved in the present invention are not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] like Figure 1 As shown, this invention provides a dual closed-loop power control method based on positive current feedback, comprising the following steps:

[0038] Step 1: Establish a dual closed-loop control structure with positive current feedback. The dual closed-loop control structure includes an inner current control loop and an outer voltage control loop. The inner current control loop uses the positive current as the feedback signal, and the outer voltage control loop uses the output voltage as the feedback signal.

[0039] Step 2: In the inner current control loop, based on the positive current feedback signal, a proportional-integral-derivative control strategy is used for current control.

[0040] Step 3: In the outer voltage control loop, voltage control is performed using a proportional-integral control strategy based on the difference between the actual output voltage value and the set value.

[0041] Step 4: Add the output of the inner current control loop to the output of the outer voltage control loop to obtain the total control output;

[0042] Step 5: Drive the power switching devices based on the total control output to achieve power control.

[0043] In this embodiment, it should be specifically explained that the inner loop current control loop collects the actual value of the positive current. In a three-phase system, the current values ​​of phase A, phase B, and phase C can be collected separately. After coordinate transformation, the direct-axis current value and the quadrature-axis current value are obtained, and the output voltage command is used to control the current in the power system. The outer loop voltage control loop collects the actual value of the output voltage and compares it with the preset voltage reference value to generate a voltage loop error signal. The output voltage control signal is used to control the output voltage of the power system.

[0044] The purpose is that positive current feedback is directly related to the conduction state of power devices and the energy transmission path. Compared with negative current or total current feedback, the dual closed-loop control structure with positive current feedback can reflect current fluctuations when the load changes suddenly, such as the instantaneous current surge when driving an electric vehicle, and avoid control delay caused by feedback signal lag, so as to improve the dynamic response speed of power control.

[0045] In this embodiment, it should be specifically noted that in step two, the current control using a proportional-integral-derivative control strategy is expressed as follows:

[0046] Among them, u pI (t) represents the output of the inner loop current control loop at time t, K pI The proportional gain of the inner current control loop determines its ability to respond quickly to errors; a larger value results in a faster response, but an excessively large proportional gain can cause oscillations. K iI K represents the reciprocal of the integral time constant of the inner loop current control loop, used to eliminate steady-state current error. iI The larger the value of K, the stronger the integral action in the proportional-integral-derivative control strategy, and the more it can suppress long-term static deviation; dI This represents the differential time constant of the inner current control loop. By differentiating the current error, its changing trend is predicted, overshoot is suppressed, damping characteristics are improved, and current oscillations during sudden load changes are reduced; e I(t) represents the current error at time t, e I (t)=I * (t)-I r (t), where I * (t) represents the positive current setting value of the inner loop current control loop at time t, I r (t) represents the actual value of the positive current of the inner loop current control loop at time t; the current setting value can be set according to different control targets. If the control target is a motor, the current setting value can be the rated operating current of the motor. If the control target is a battery, the current setting value can be the stable charging current of the battery.

[0047] By leveraging the synergistic effect of the proportional coefficient, integral time constant, and derivative time constant of the inner current control loop, high-precision tracking of the positive current is achieved. In the inner current control loop, the proportional coefficient is used for fast response, the integral time constant is used to eliminate steady-state error, and the derivative time constant is used to suppress overshoot. As a fast-response loop, the inner current control loop can adjust the control output in milliseconds during load surges, ensuring that the current converges quickly to the given value and avoiding the risk of overcurrent in power devices due to current fluctuations. These load surges include sudden load increases and motor startup.

[0048] In this embodiment, it should be specifically noted that in step three, the voltage control based on the difference between the output voltage and the given voltage using a proportional-integral control strategy is expressed as follows:

[0049] Among them, u pV (t) represents the output of the outer loop voltage control loop at time t, K pV The proportional gain of the outer voltage control loop determines its response speed to errors and can be matched with the inertial time constant to avoid voltage oscillations; K iV This represents the reciprocal of the integral time constant of the outer loop voltage control loop, used to eliminate steady-state voltage errors, such as voltage deviations caused by long-term load changes. The integral action accumulates historical errors and continuously adjusts, ensuring long-term stability of the output voltage; e V (t) represents the voltage error at time t, e V (t)=U * (t)-U r (t), where U * (t) represents the output voltage setpoint of the outer loop voltage control loop at time t, U r (t) represents the actual output voltage value of the outer loop voltage control loop at time t; the output voltage setting value can be set according to different control targets. If the control target is a motor, the output voltage setting value can be the rated operating voltage of the motor. If the control target is a battery, the output voltage setting value can be the battery charging target voltage.

[0050] By combining the proportional coefficient and integral time constant of the outer voltage control loop, steady-state high-precision control of the output voltage is achieved. In the outer voltage control loop, the proportional coefficient is used to quickly respond to voltage deviations, and the integral time constant is used to accumulate and adjust to eliminate steady-state error. As a slow-response loop, the outer voltage control loop can slowly adjust the control output when there are long-term load changes or input voltage fluctuations, avoiding oscillations caused by frequent actions of the inner current control loop, while providing a stable reference for the inner current control loop. The long-term load changes are such as the continuous high-current discharge when an electric vehicle is climbing a hill, and the input voltage fluctuations are such as the drop in grid voltage.

[0051] In this embodiment, it should be specifically noted that step four, which involves adding the output of the inner current control loop to the output of the outer voltage control loop to obtain the total control output, is expressed as follows:

[0052] u all (t)=u pI (t)+u pV (t); where u all (t) represents the total control output at time t, which is used as the drive command for the power device after being limited;

[0053] By adding the output of the inner current control loop to the output of the outer voltage control loop, the synergistic optimization of "fast response" and "stable regulation" is achieved in the form of output superposition. The inner current control loop can quickly suppress current fluctuations, such as instantaneous current surges caused by load changes, to ensure that power devices operate within a safe current range. The outer voltage control loop can slowly correct voltage deviations, such as voltage shifts caused by long-term load changes, to avoid oscillations caused by over-regulation of the inner current control loop. The combination of the two can simultaneously achieve millisecond-level dynamic response speed and microsecond-level steady-state regulation accuracy, solving the contradiction of traditional single closed-loop control being "fast but unstable" or "stable but not fast".

[0054] The amplitude limiting process consists of two main aspects: first, amplitude limiting, which sets strict upper and lower voltage limits based on the rated voltage or rated current of the power device to ensure that the absolute value of the final total control output does not exceed the safe range. The amplitude limiting can be implemented using piecewise functions or clamping circuits. Second, anti-saturation limiting, which is a protection mechanism specifically for the integral stage of PID and PI controllers. It aims to prevent the continuous and significant accumulation of the integral term inside the controller due to actuator saturation (such as when the output voltage has reached the upper limit), thereby causing slow system response or oscillation. The anti-saturation limiting can be implemented using methods such as integral reset, conditional integration, and clamping (output clamping to pause integration). After amplitude limiting, a drive signal is obtained, and this drive signal serves as the drive command for the power device.

[0055] In this embodiment, it should be specifically noted that the output of the inner current control loop is a voltage command, which is essentially a voltage control signal. Its purpose is to control the current in the power system. This voltage control signal is used to drive the PWM modulator or directly as the control input of some power devices to achieve the desired current value.

[0056] The output of the outer loop voltage control loop is also a voltage control signal, which serves as the input of the PWM modulator or the control input of certain power devices. Its purpose is to control the output voltage of the power system.

[0057] In step four, adding the output of the inner current control loop to the output of the outer voltage control loop is essentially synthesizing two control signals, which can be called signal synthesis or command synthesis. Its purpose is to integrate multiple control objectives and optimize the control performance of the power system. For example, in a motor drive system, the inner current control loop is responsible for fast response and precise torque or flux control, while the outer voltage control loop is responsible for ensuring the quality and stability of the overall output voltage. By combining the outputs of the two, the dual objectives of "fast response" and "stable power supply" can be achieved.

[0058] In this embodiment, it should be specifically noted that in step five, the driving command is converted into a switching signal using a pulse width modulation algorithm to drive the power device and achieve power control. The energy conversion control of the power system is achieved by adjusting the duty cycle of the device. The driving command is the total control output of the driving command for the power device after being limited in step four.

[0059] A protection mechanism can be set during the power control process, specifically:

[0060] The system has preset current and voltage thresholds. When the actual value of the positive current exceeds the current threshold or the actual value of the output voltage exceeds the voltage threshold, the protection mechanism is triggered.

[0061] The protection mechanism is manifested as follows:

[0062] Limit the range of the total control output value to force power devices to operate at reduced derating to avoid damage from overcurrent or overvoltage; synchronously send fault signals and trigger shutdown protection;

[0063] By using PWM drive to convert control signals into actual power regulation actions, precise energy control of the load can be achieved. If combined with protection mechanisms, it can quickly respond and safely shut down in extreme conditions such as short circuits and overloads, thereby improving the reliability of power control.

[0064] like Figure 2As shown, the present invention provides a dual closed-loop power control system based on positive current feedback, including a positive current detection module, a negative current detection module, a voltage detection module, an inner loop controller, an outer loop controller, a PID controller, and a power conversion module;

[0065] The positive current detection module is used to detect the positive current.

[0066] The negative electrode current detection module is used to detect the negative electrode current;

[0067] The voltage detection module is used to detect the input voltage and the output voltage;

[0068] The inner loop controller uses the positive current as a feedback signal and outputs a voltage command to control the current in the power system.

[0069] The outer loop controller is used to collect the actual value of the output voltage and compare it with the preset voltage reference value to generate a voltage loop error signal. The output voltage control signal is used to control the output voltage of the power system.

[0070] The PID controller uses a proportional-integral-derivative control strategy for current control based on the positive current feedback signal; and uses a proportional-integral control strategy for voltage control based on the difference between the actual output voltage value and the set value.

[0071] The power conversion module adds the output of the inner loop controller to the output of the outer loop controller to obtain the total control output; based on the total control output, the power switching device is driven to achieve power control.

[0072] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0073] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A dual closed-loop power control method based on positive current feedback, characterized in that: Includes the following steps: Step 1: Establish a dual closed-loop control structure with positive current feedback. The dual closed-loop control structure includes an inner current control loop and an outer voltage control loop. The inner current control loop uses the positive current as the feedback signal, and the outer voltage control loop uses the output voltage as the feedback signal. Step 2: In the inner current control loop, based on the positive current feedback signal, a proportional-integral-derivative control strategy is used for current control. Step 3: In the outer voltage control loop, voltage control is performed using a proportional-integral control strategy based on the difference between the actual output voltage value and the set value. Step 4: Add the output of the inner current control loop to the output of the outer voltage control loop to obtain the total control output; Step 5: Drive the power switching devices based on the total control output to achieve power control.

2. The dual closed-loop power control method based on positive current feedback according to claim 1, characterized in that: The inner current control loop acquires the actual value of the positive current and outputs a voltage command to control the current in the power system; the outer voltage control loop acquires the actual value of the output voltage and compares it with a preset voltage reference value to generate a voltage loop error signal, and outputs a voltage control signal to control the output voltage of the power system.

3. The dual closed-loop power control method based on positive current feedback according to claim 2, characterized in that: In step two, the current control using a proportional-integral-derivative control strategy is expressed as follows: Among them, u pI (t) represents the output of the inner loop current control loop at time t, K pI K represents the proportional gain of the inner current control loop. iI K represents the reciprocal of the integral time constant of the inner loop current control loop. dI e represents the differential time constant of the inner loop current control loop. I (t) represents the current error at time t.

4. The dual closed-loop power control method based on positive current feedback according to claim 3, characterized in that: The e I (t) is represented as: e I (t)=I * (t)-I r (t), where I * (t) represents the positive current setting value of the inner loop current control loop at time t, I r (t) represents the actual value of the positive current of the inner loop current control loop at time t.

5. The dual closed-loop power control method based on positive current feedback according to claim 4, characterized in that: In step three, voltage control based on the difference between the output voltage and the given voltage is expressed as follows: Among them, u pV (t) represents the output of the outer loop voltage control loop at time t, K pV K represents the proportional gain of the outer loop voltage control loop. iV e represents the reciprocal of the integral time constant of the outer loop voltage control loop. V (t) represents the voltage error at time t.

6. The dual closed-loop power control method based on positive current feedback according to claim 5, characterized in that: The e V (t) is represented as: e V (t)=U * (t)-U r (t), where U * (t) represents the output voltage setpoint of the outer loop voltage control loop at time t, U r (t) represents the actual output voltage of the outer loop voltage control loop at time t.

7. The dual closed-loop power control method based on positive current feedback according to claim 6, characterized in that: Step four involves adding the output of the inner current control loop to the output of the outer voltage control loop to obtain the total control output, expressed as follows: u all (t)=u pI (t)+u pV (t); where u all (t) represents the total control output at time t, which is used as the drive command for the power device after being limited.

8. The dual closed-loop power control method based on positive current feedback according to claim 7, characterized in that: In step five, the driving command is converted into a switching signal using a pulse width modulation algorithm to drive the power device and achieve power control. The energy conversion control of the power system is achieved by adjusting the duty cycle of the device.

9. A dual-closed-loop power control system based on positive current feedback, used in the dual-closed-loop power control method based on positive current feedback as described in any one of claims 1-8, characterized in that: It includes a positive current detection module, a negative current detection module, a voltage detection module, an inner loop controller, an outer loop controller, a PID controller, and a power conversion module; The positive current detection module is used to detect the positive current. The negative electrode current detection module is used to detect the negative electrode current; The voltage detection module is used to detect the input voltage and the output voltage; The inner loop controller uses the positive current as a feedback signal and outputs a voltage command to control the current in the power system. The outer loop controller is used to collect the actual value of the output voltage and compare it with the preset voltage reference value to generate a voltage loop error signal. The output voltage control signal is used to control the output voltage of the power system. The PID controller uses a proportional-integral-derivative control strategy for current control based on the positive current feedback signal; and uses a proportional-integral control strategy for voltage control based on the difference between the actual output voltage value and the set value. The power conversion module adds the output of the inner loop controller to the output of the outer loop controller to obtain the total control output; based on the total control output, the power switching device is driven to achieve power control.

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