Three-phase PFC current sensorless single voltage loop control method

Abstract

This invention discloses a sensorless single-voltage loop control method for three-phase PFC (Power Factor Correction) converters. This method eliminates traditional current sensors and complex current observers, collecting only the output DC voltage and grid voltage. Using the output DC voltage as the sole feedback quantity, the single-voltage loop controller obtains the d-axis current command, and then directly obtains the target voltage vector through analytical calculation. The target voltage vector is then generated through coordinate transformation and modulation to produce a switching transistor drive signal, achieving power factor correction and stable output voltage control. This invention significantly simplifies the hardware and control architecture, reducing cost and size. It exhibits high robustness to inductor mismatch, with output voltage fluctuation ≤ ±2% and power factor ≥ 0.99 when inductor parameters are mismatched from -40% to +50%. Furthermore, it is adaptable to various three-phase rectifier topologies and suitable for low-cost, high-reliability engineering applications of three-phase PFC converters.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology, specifically relating to a sensorless single-voltage loop control method for three-phase PFC. Background Technology

[0002] Three-phase power factor correction (PFC) converters are core components of power electronic devices, primarily responsible for optimizing the power factor of the power grid, suppressing harmonic pollution, and ensuring stable operation of the output DC voltage. To reduce hardware costs and equipment size, sensorless control has become a research hotspot in the field of three-phase PFC, with the core objective of eliminating current sensors and simplifying the hardware architecture.

[0003] Currently, mainstream sensorless control solutions for three-phase PFC generally have significant technical shortcomings: most solutions rely on complex current observers to indirectly estimate grid current or inductor current. These observers are extremely sensitive to changes in circuit parameters, especially when inductor parameters are mismatched, the observation accuracy will be greatly reduced, directly leading to deterioration of control performance and decrease in system stability. At the same time, complex current observers will significantly increase the complexity of digital control architecture, increase the difficulty of software development and the computational burden on the chip. In addition, some sensorless control solutions are only compatible with a single rectifier topology, with extremely poor versatility, making it difficult to meet the needs of multi-scenario engineering applications. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a sensorless single-voltage loop control method for three-phase PFC. This method abandons traditional current sensors and complex current observers, collecting only the output DC voltage and grid voltage. Using the output DC voltage as the sole feedback quantity, the single-voltage loop controller obtains the d-axis current setpoint, and then directly obtains the target voltage vector through analytical calculation. The target voltage vector is then generated through coordinate transformation and modulation to achieve power factor correction and stable output voltage control. This invention significantly simplifies the hardware and control architecture, reduces cost and size, and exhibits high robustness to inductor mismatch. When the inductor parameter mismatch is -40% to +50%, the output voltage fluctuation is ≤±2%, and the power factor is ≥0.99. Furthermore, it is adaptable to various three-phase rectifier topologies and is suitable for low-cost, high-reliability engineering applications of three-phase PFC converters.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows: Step 1: Collect the three-phase grid voltage and output DC voltage of the three-phase PFC converter, perform Clark transformation on the three-phase grid voltage to obtain the voltage components in the αβ coordinate system, and then obtain the grid voltage amplitude, phase and angular frequency parameters through phase-locked loop calculation as the basic data for voltage vector calculation; at the same time, use the output DC voltage as the only feedback quantity of the single voltage loop, without introducing any current feedback signal; Step 2: Calculate the difference between the acquired output DC voltage and the preset reference voltage to obtain the voltage deviation signal. Input the deviation signal into the single voltage loop controller. After adjustment and calculation, the d-axis current setpoint is obtained. This parameter is used to regulate the stable value of the output DC voltage. Step 3: Combining the grid voltage amplitude, angular frequency, d-axis current, and inductance parameters, directly calculate the voltage vector in the dq coordinate system using a preset analytical formula; Step 4: The calculated dq voltage vector is converted into a three-phase stationary coordinate system voltage signal through inverse Park transform and inverse Clark transform. Then, the driving signal of the three-phase PFC converter switching transistor is generated through conventional modulation to control the orderly switching of the power circuit. Step 5: Input the drive signal into the three-phase PFC power circuit to realize AC to DC power conversion, simultaneously complete power factor correction, ensure grid current tracks voltage phase, and maintain stable output DC voltage.

[0006] Preferably, the formula for calculating the voltage vector in the dq coordinate system is:

[0007] In the formula: The voltage amplitude of the power grid. The angular frequency of the power grid. Inductance value The sampling period is The d-axis current is given.

[0008] Preferably, the conventional modulation method is SVPWM modulation or SPWM modulation.

[0009] Preferably, the single voltage loop controller is a PI controller or a model predictive controller.

[0010] Preferably, the three-phase PFC sensorless single-voltage loop control method is adaptable to various three-phase rectifier topologies, including any one of three-phase two-level rectifier topologies, three-phase three-level rectifier topologies, Vienna topologies, and ANPC topologies.

[0011] An electronic device includes a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to enable the electronic device to perform the above-described three-phase PFC sensorless single-voltage loop control method.

[0012] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described three-phase PFC sensorless single-voltage loop control method.

[0013] A chip includes a processor for calling and running a computer program from a memory, causing a device equipped with the chip to perform the above-described three-phase PFC sensorless single-voltage loop control method.

[0014] A computer program product includes a computer storage medium storing a computer program, the computer program including instructions executable by at least one processor, which, when executed by the at least one processor, implement the above-described three-phase PFC sensorless single-voltage loop control method.

[0015] The beneficial effects of this invention are as follows: First, it simplifies both the hardware and control architecture. By completely eliminating the current sensor and the complex current observer, it reduces hardware procurement costs and system size, simplifies digital control logic, reduces the computational burden on the control chip, and lowers the difficulty of software development and debugging.

[0016] Second, it exhibits extremely strong robustness against inductor mismatch. By eliminating the parameter-sensitive current observer, inductor parameter deviations can be automatically compensated through closed-loop control. When the measured inductor parameters are mismatched within the range of -40% to +50%, the output DC voltage fluctuation does not exceed ±2%, the power factor remains stable above 0.99, and the control performance is not significantly affected.

[0017] Third, it has high topology adaptability and versatility. The method is not limited to a single rectifier topology; it can be adapted to various three-phase rectifier topologies such as three-phase two-level, three-level, Vienna, and ANPC. Only the midpoint of the bridge arm needs to output the target modulation voltage, making it suitable for a wide range of scenarios.

[0018] Fourth, the control logic is simple and easy to deploy. It adopts a single-voltage closed-loop control, which is simpler to tune parameters and easier to implement in engineering compared to the traditional voltage-current dual-loop control. At the same time, it can take into account both high power factor and voltage regulation performance, combining economy and practicality. Attached Figure Description

[0019] Figure 1 This is an overall block diagram of the sensorless single-voltage loop control method for three-phase PFC of the present invention; Figure 2 This is a flowchart of the implementation steps of the control method of the present invention; Figure 3 This is a schematic diagram of the three-phase two-level PFC topology in Example 1; Figure 4 This is a schematic diagram of the voltage vector calculation principle and steady-state rotating current vector of the present invention; Figure 5 This is the system operating waveform diagram when the inductance parameter is mismatched by -40% in Example 1; Figure 6This is the system operating waveform diagram when the inductance parameter of Example 1 is mismatched by +50%. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] This invention aims to overcome the core pain points of existing three-phase PFC sensorless control technology: first, to get rid of the dependence on complex current observers and solve the problem that the observers are highly sensitive to changes in parameters such as inductor mismatch; second, to simplify the digital control architecture and reduce hardware costs and system size; and third, to break the topology adaptation limitation and improve the versatility of the control method, ultimately achieving low-cost, highly robust and easy-to-deploy three-phase PFC sensorless control.

[0022] The following is a unified explanation of the general symbols used throughout this invention: The voltage amplitude of the power grid. The angular frequency of the power grid. The inductance value of the three-phase PFC converter. The sampling period is Given the d-axis current, The voltage vector in the dq coordinate system. To output DC voltage, This is the reference value for the output DC voltage. , The voltage components of the power grid are in the αβ coordinate system.

[0023] The method of this invention does not use current sensors or current observers throughout the entire process; it only collects two types of voltage signals: output DC voltage and grid voltage, thus achieving single-voltage closed-loop control. The specific implementation steps are as follows: The first step is to collect the three-phase grid voltage and output DC voltage of the three-phase PFC converter, perform Clark transformation on the three-phase grid voltage to obtain the voltage components in the αβ coordinate system, and then obtain the grid voltage amplitude, phase and angular frequency parameters through phase-locked loop calculation as the basic data for voltage vector calculation; at the same time, the output DC voltage is used as the only feedback quantity of the single voltage loop, without introducing any current feedback signal.

[0024] The second step is to perform a difference calculation between the acquired output DC voltage and the preset reference voltage to obtain a voltage deviation signal. This deviation signal is then input into a single voltage loop controller, and after adjustment and calculation, the d-axis current setpoint is obtained. This parameter is used to regulate the stable value of the output DC voltage.

[0025] The third step involves combining the grid voltage amplitude, angular frequency, d-axis current, and inductor parameters to directly calculate the voltage vector in the dq coordinate system using a preset analytical formula. This process completely bypasses the current observation stage and does not require the construction of any current observation model. Since the inductor parameters participate in the calculation in the form of a product, the error caused by parameter mismatch can be automatically compensated by the closed-loop controller, further improving the robustness of the system.

[0026] The fourth step is to convert the calculated dq voltage vector into a three-phase stationary coordinate system voltage signal through inverse Park transform and inverse Clark transform, and then generate a switching transistor drive signal through conventional modulation to control the orderly switching of the power circuit.

[0027] The fifth step is to input the drive signal into the three-phase PFC power circuit to realize the AC to DC power conversion, simultaneously complete the power factor correction, ensure that the grid current tracks the voltage phase, and maintain the stability of the output DC voltage.

[0028] Example 1: Three-phase two-level PFC topology control; This embodiment uses a three-phase two-level rectifier topology, and its topology diagram is as follows: Figure 3 As shown, the single-voltage loop controller uses a PI controller, and the drive signal uses SVPWM modulation. The control block diagram is as follows. Figure 1 As shown, Figure 1 The flowchart clearly illustrates the complete chain of "voltage acquisition - single voltage loop control - voltage vector calculation - modulation drive - power circuit", highlighting the core characteristics of no current sensor and no current observer; the corresponding flowchart is as follows: Figure 2 As shown. The specific implementation process is as follows: S1. Acquire the three-phase grid voltage through a voltage sampling circuit. , , With output DC voltage The sampled signal is filtered and noise-reduced by RC before being input into the digital control chip. No current sensor is installed or current signal is collected throughout the process.

[0029] S2. Calculate the output DC voltage Compared with reference value deviation The deviation is input to the PI controller, and after proportional-integral adjustment, the d-axis current command is obtained. .

[0030] S3. Perform Clark transformation on the three-phase grid voltage to obtain , Through the voltage vector magnitude formula Calculate the grid voltage amplitude, then perform Park transform and phase-locked loop operations to obtain the grid angular frequency and phase; according to... Figure 4The steady-state rotating current injected into the inductor by the switching network shown can be solved using the inductor's dynamic equations to obtain the corresponding dq voltage vector:

[0031] By combining the aforementioned parameters and the given d-axis current, the dq voltage vector is calculated using the voltage vector formula, without any current observation step throughout the process.

[0032] S4. After the dq voltage vector is transformed by inverse Park and inverse Clark, it is input into the SVPWM modulation module to generate the PWM drive signal for the switching transistor, and to precisely control the on / off timing of the switching transistor.

[0033] S5. Input the drive signal into the three-phase two-level PFC power circuit to achieve power factor correction and output voltage regulation. The grid current can accurately track the voltage phase, achieving a high power factor operation effect.

[0034] Through actual measurement and verification, when the inductor parameters in this embodiment exhibit a mismatch between -40% and +50%, the corresponding output voltage, power factor, and input current waveforms are as follows: Figure 5 and Figure 6 As shown, the output DC voltage fluctuation is ≤±2%, and the power factor is ≥0.99, which fully demonstrates the high robustness of the method.

[0035] Example 2: Three-level ANPC PFC topology control; The difference between this embodiment and Embodiment 1 is that a three-level ANPC rectifier topology is selected, a model predictive controller is used for the single voltage loop controller, and the drive signal adopts SPWM modulation. The rest of the control process is completely the same as that of Embodiment 1.

[0036] Through actual testing, it has been verified that when the inductor parameters are mismatched by -40% and +50%, the output DC voltage fluctuation is ≤±2% and the power factor is ≥0.99. Stable power factor correction and output voltage control can still be achieved, which fully demonstrates the universal adaptability of this invention to various three-phase rectifier topologies.

Claims

1. A sensorless single-voltage loop control method for three-phase PFC, characterized in that, Includes the following steps: Step 1: Collect the three-phase grid voltage and output DC voltage of the three-phase PFC converter, perform Clark transformation on the three-phase grid voltage to obtain the voltage components in the αβ coordinate system, and then obtain the grid voltage amplitude, phase and angular frequency parameters through phase-locked loop calculation as the basic data for voltage vector calculation; at the same time, use the output DC voltage as the only feedback quantity of the single voltage loop, without introducing any current feedback signal; Step 2: Calculate the difference between the acquired output DC voltage and the preset reference voltage to obtain the voltage deviation signal. Input the deviation signal into the single voltage loop controller. After adjustment and calculation, the d-axis current setpoint is obtained. This parameter is used to regulate the stable value of the output DC voltage. Step 3: Combining the grid voltage amplitude, angular frequency, d-axis current, and inductance parameters, directly calculate the voltage vector in the dq coordinate system using a preset analytical formula; Step 4: The calculated dq voltage vector is converted into a three-phase stationary coordinate system voltage signal through inverse Park transform and inverse Clark transform. Then, the driving signal of the three-phase PFC converter switching transistor is generated through conventional modulation to control the orderly switching of the power circuit. Step 5: Input the drive signal into the three-phase PFC power circuit to realize AC to DC power conversion, simultaneously complete power factor correction, ensure grid current tracks voltage phase, and maintain stable output DC voltage.

2. The three-phase PFC sensorless single-voltage loop control method according to claim 1, characterized in that, A sensorless single-voltage loop control method for three-phase PFC, characterized in that the voltage vector calculation formula in the dq coordinate system is: In the formula: The voltage amplitude of the power grid. The angular frequency of the power grid. Inductance value The sampling period is The d-axis current is given.

3. The three-phase PFC sensorless single-voltage loop control method according to claim 1, characterized in that, The conventional modulation method is SVPWM modulation or SPWM modulation.

4. The three-phase PFC sensorless single-voltage loop control method according to claim 1, characterized in that, The single voltage loop controller employs either a PI controller or a model predictive controller.

5. A sensorless single-voltage loop control method for three-phase PFC according to claim 1, characterized in that, The three-phase PFC sensorless single-voltage loop control method is compatible with various three-phase rectifier topologies, including any one of the following: three-phase two-level rectifier topology, three-phase three-level rectifier topology, Vienna topology, and ANPC topology.

6. An electronic device, characterized in that, include: Processor and memory; The memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to cause the electronic device to perform the method as described in any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 5.

8. A chip, characterized in that, include: A processor for retrieving and running a computer program from memory, causing a device on which the chip is mounted to perform the method as described in any one of claims 1 to 5.

9. A computer program product, characterized in that, The computer program product includes a computer storage medium storing a computer program, the computer program including instructions executable by at least one processor, which, when executed by the at least one processor, implement the method as described in any one of claims 1 to 5.

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