An energy feedback algorithm of deadbeat current prediction

Abstract

This invention discloses an energy feedback algorithm for predicting deadbeat current. The energy feedback algorithm includes a deadbeat current prediction control algorithm, a voltage PI regulator, and a power grid self-learning algorithm. Specifically, it includes the following steps: S1, sampling the A and B phase currents of reactor L1. A i B and the DC voltage V on the bus side DC S2. Based on the coordinate transformation method from a three-phase coordinate system to a two-phase stationary coordinate system, calculate the actual two-phase current i in the two-phase stationary coordinate system. α i β This invention employs a deadbeat current prediction-based energy feedback algorithm, eliminating the need for a grid voltage detection device. It can learn the grid voltage and phase in real time and use the sampled voltage loop PI regulator output to control the magnitude of the feedback current.

Description

Technical Field

[0001] This invention relates to the field of energy feedback system technology, and in particular to an energy feedback algorithm for predicting deadbeat current. Background Technology

[0002] Conventional frequency converters dissipate energy through braking resistors, while conventional energy feedback control uses additional sensors to detect grid-side voltage and phase, which is subject to interference and delay. This invention utilizes a deadbeat-free current predictive control algorithm that eliminates the need for additional voltage and phase detection devices. It learns the grid voltage and phase in real time, resulting in a faster current control response and enabling energy feedback with a power factor of 1. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing an energy feedback algorithm for deadbeat current prediction.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An energy feedback control method, wherein the energy feedback algorithm includes a deadbeat current prediction control algorithm, a voltage PI regulator, and a power grid self-learning algorithm, specifically including the following steps:

[0006] S1. Sample the A and B phase currents of reactor L1. A i B and the DC voltage V on the bus side DC ;

[0007] S2. Based on the coordinate transformation method from a three-phase coordinate system to a two-phase stationary coordinate system, calculate the actual two-phase current i in the two-phase stationary coordinate system. α i β ;

[0008] S3. Determine the bus side voltage V DC Is the current value greater than the initial feedback voltage value V? DC_start ;

[0009] S4, when the bus side voltage V DC The current value is greater than the initial feedback voltage value V. DC_start The switch tube is controlled to switch on and off so that the grid voltage is applied to the reactor.

[0010] S5. Calculate the feedback control current command i using the voltage PI regulator. s * ;

[0011] S6. Based on the estimated phase θ and feedback control current i s *Calculate the two-phase current command i in the two-phase stationary coordinate system. α * i β * ;

[0012] S7, according to the command current i α * i β * and the estimated grid voltage e α e β A deadbeat current predictive control algorithm is used to calculate the two-phase voltage V in the two-phase stationary coordinate system. α * V β * ;

[0013] S8, according to V α * V β * Calculate the SVPWM output and update the pulse width modulation module output to the switching transistor. Output energy to the power grid;

[0014] S9. Estimate the two-phase grid voltage e in the two-phase stationary coordinate system by detecting the change in reactor current. α e β ;

[0015] S10. By performing arctangent calculation on the two-phase voltage, calculate the current grid voltage value and angle information, as well as predict the next grid voltage value and the next angle position θ.

[0016] S11. Determine the bus side voltage V DC Is the current value less than the stop feedback voltage value V? DC_stop It also detects the magnitude of the feedback current and determines whether the current feedback current is less than the minimum feedback current i. min_stop ;

[0017] Preferably, in S9, a dual-loop control is adopted based on the deadbeat current prediction control. The prediction current control only performs Clarke changes and does not require a decoupling algorithm to calculate the output voltage.

[0018] Preferably, in step S8, the two-phase voltage in the grid voltage stationary coordinate system can be calculated in real time, and the phase of the current grid voltage can be calculated by arctangent calculation.

[0019] Preferably, the following formula is used:

[0020]

[0021] After discretization, it becomes:

[0022]

[0023] Calculated voltage output value at the next moment:

[0024]

[0025] The calculated value of the feedback voltage at this moment:

[0026]

[0027] The calculated value of the back electromotive force at this moment:

[0028]

[0029] Iterate equation (5) to equation (3) to calculate the two voltages in the stationary coordinate system. The SVPWM vector generation module utilizes the aforementioned voltage, and the pulse width modulation module controls the six switching transistors on the rectifier side.

[0030] In step (8), the two-phase voltage in the static coordinate system of the grid voltage can be calculated in real time using formula (5). The phase of the current grid voltage is then calculated using the arctangent of formula (6).

[0031]

[0032] The voltage on the bus side is adjusted in real time by a voltage PI regulator, and its output is used as the feedback control current is*. Using formula (7), it is decomposed into two-phase control current in the stationary coordinate system.

[0033]

[0034] Substitute the current control variable from formula (7) into (3) to complete a full feedback control algorithm implementation.

[0035] Preferably, the value marked with an asterisk (*) represents a predicted value, while the value without an asterisk (*) represents a feedback value.

[0036] The beneficial effects of this invention are:

[0037] 1. By directly connecting the feedback reactor L1 between the power grid and the frequency converter, the method includes: real-time detection of the bus side voltage value and determination of whether the value is greater than the initial feedback voltage value. When the value is greater than the initial feedback voltage value, the output state of the IGBT switch is controlled to act on the feedback reactor.

[0038] 2. By detecting the change in reactor current and calculating the current grid voltage and phase, a feedback current is output to the grid based on the learned phase. The bus voltage drops. When the bus voltage drops to the stop voltage and the feedback current is less than a certain set minimum feedback current value, the feedback stops.

[0039] In summary, this invention employs a deadbeat current prediction-based energy feedback algorithm that eliminates the need for a grid voltage detection device. It can learn the grid voltage and phase in real time and use the sampling voltage loop PI regulator output to control the magnitude of the feedback current. Attached Figure Description

[0040] Figure 1 This is a structural diagram of a four-quadrant frequency converter (rectifier feedback side) for an energy feedback algorithm with deadbeat current prediction proposed in this invention. Detailed Implementation

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0042] Reference Figure 1 An energy feedback algorithm for deadbeat current prediction is proposed. The energy feedback algorithm includes a deadbeat current prediction control algorithm, a voltage PI regulator, and a power grid self-learning algorithm. Specifically, it includes the following steps:

[0043] S1. Sample the A and B phase currents of reactor L1. A i B and the DC voltage V on the bus side DC ;

[0044] S2. Based on the coordinate transformation method from a three-phase coordinate system to a two-phase stationary coordinate system, calculate the actual two-phase current i in the two-phase stationary coordinate system. α i β ;

[0045] S3. Determine the bus side voltage V DC Is the current value greater than the initial feedback voltage value V? DC_start ;

[0046] S4, when the bus side voltage V DC The current value is greater than the initial feedback voltage value V. DC_start The switch tube is controlled to switch on and off so that the grid voltage is applied to the reactor.

[0047] S5. Calculate the feedback control current command i using the voltage PI regulator. s * ;

[0048] S6. Based on the estimated phase θ and feedback control current i s * Calculate the two-phase current command i in the two-phase stationary coordinate system. α * i β* ;

[0049] S7, according to the command current i α * i β * and the estimated grid voltage e α e β A deadbeat current predictive control algorithm is used to calculate the two-phase voltage V in the two-phase stationary coordinate system. α * V β * ;

[0050] S8, according to V α * V β * Calculate the SVPWM output and update the pulse width modulation module output to the switching transistor. Output energy to the power grid;

[0051] S9. Estimate the two-phase grid voltage e in the two-phase stationary coordinate system by detecting the change in reactor current. α e β ;

[0052] S10. By performing arctangent calculation on the two-phase voltage, calculate the current grid voltage value and angle information, as well as predict the next grid voltage value and the next angle position θ.

[0053] S11. Determine the bus side voltage V DC Is the current value less than the stop feedback voltage value V? DC_stop It also detects the magnitude of the feedback current and determines whether the current feedback current is less than the minimum feedback current i. min_stop ;

[0054] In this invention, S9 uses dual-loop control based on deadbeat current prediction control. The prediction current control only performs Clarke changes and does not require a decoupling algorithm. The output voltage is calculated according to the following formula.

[0055] (1) Voltage equation in stationary coordinates:

[0056]

[0057] After discretization, it becomes:

[0058]

[0059] Calculated voltage output value at the next moment:

[0060]

[0061] The calculated value of the feedback voltage at this moment:

[0062]

[0063] The calculated value of the back electromotive force at this moment:

[0064]

[0065] Iterate equation (5) to equation (3) to calculate the two voltages in the stationary coordinate system. Using the voltage mentioned above to generate the SVPWM vector, and using the pulse width modulation module to control the six switching transistors on the rectifier side, without a beat current prediction algorithm, it is necessary to generate the stationary two-phase command current. In S8, the two-phase voltage under the stationary coordinate system of the grid voltage can be calculated in real time, and the phase of the current grid voltage can be calculated according to the arctangent of formula (6).

[0066]

[0067] The voltage on the bus side is adjusted in real time by a voltage PI regulator, and its output is used as the feedback control current is*. Using formula (7), it is decomposed into two-phase control current in the stationary coordinate system.

[0068]

[0069] Substitute the current control variable from formula (7) into (3) to complete a full feedback control algorithm implementation.

[0070] In this invention, the feedback reactor L1 is directly connected between the power grid and the frequency converter. It detects the bus voltage value in real time and determines whether the value is greater than the initial feedback voltage value. When the value is greater than the initial feedback voltage value, it controls the output state of the IGBT switch to act on the feedback reactor. By detecting the change in reactor current and calculating the current grid voltage and phase, it outputs feedback current to the grid according to the learned phase, and the bus voltage drops. When the bus voltage drops to the stop voltage and the feedback current is less than a certain set minimum feedback current value, the feedback stops.

[0071] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An energy feedback algorithm for predicting deadbeat current, characterized in that, The energy feedback algorithm includes a deadbeat current prediction control algorithm, a voltage PI regulator, and a power grid self-learning algorithm, specifically including the following steps: S1. Sample the A and B phase currents of reactor L1. , and DC voltage on the bus side ; S2. Based on the coordinate transformation method from a three-phase coordinate system to a two-phase stationary coordinate system, calculate the actual two-phase current in the two-phase stationary coordinate system. , ; S3. Determine the bus side voltage. Is the current value greater than the initial feedback voltage value? ; S4, when the bus side voltage The current value is greater than the initial feedback voltage value. The control switch is switched on and off so that the grid voltage is applied to the reactor; S5. Calculate the feedback control current command through the voltage PI regulator. ; S6. Based on the estimated phase and feedback control current Calculate the two-phase current command i in the two-phase stationary coordinate system. , ; S7, according to the command current , and the estimated grid voltage , A deadbeat current predictive control algorithm is used to calculate the two-phase voltage in a two-phase stationary coordinate system. , ; S8, according to , Calculate the SVPWM output and update the pulse width modulation module output to the switching transistor to supply energy to the power grid; S9. Estimate the two-phase grid voltage in the two-phase stationary coordinate system by detecting the change in reactor current. , ; S10. By performing arctangent calculation on the two-phase voltage, calculate the current grid voltage value and angle information, and predict the next grid voltage value and the next angle position. ; S11. Determine the bus side voltage. Is the current value less than the stop feedback voltage value? It also detects the magnitude of the feedback current and determines whether the current feedback current is less than the minimum feedback current. .

2. The energy feedback algorithm for deadbeat current prediction according to claim 1, characterized in that... In S9, based on the deadbeat current prediction control, a dual-loop control is adopted. The prediction current control only performs Clarke changes and does not require a decoupling algorithm to calculate the output voltage.

3. The energy feedback algorithm for deadbeat current prediction according to claim 1, characterized in that... The S8 function can calculate the two-phase voltage in the grid voltage stationary coordinate system in real time, and calculate the phase of the current grid voltage using arctangent calculation.

4. The energy feedback algorithm for deadbeat current prediction according to claim 1, characterized in that, Use the following formula: Calculated voltage output value at the next moment: Iterate equation (5) to equation (3) to calculate the two voltages in the stationary coordinate system. The SVPWM vector generation module utilizes the aforementioned voltage, and the pulse width modulation module controls the six switching transistors on the rectifier side. In S8, using formula (5), the two-phase voltage in the grid voltage stationary coordinate system can be calculated in real time, and the phase of the current grid voltage can be calculated by arctangent formula (6); The bus-side voltage is adjusted in real time by a voltage PI regulator, and its output is used as feedback control current. Using formula (7), it can be decomposed into two-phase control currents in a stationary coordinate system; Substitute the current control variable from formula (7) into (3) to complete a full feedback control algorithm. In the formula, * represents the predicted value and no * represents the feedback value.

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