Permanent magnet generator system capable of stably operating under constant power load and control method

Abstract

The present invention discloses a permanent magnet generator system and a control method that can operate stably under a constant power load, and relates to the technical field of power generation systems, including an engine, a permanent magnet generator, a rotary transformer for collecting motor rotor position signals, a three-phase full-bridge main power circuit, a current sensor for collecting motor three-phase armature winding currents, a constant power load, a voltage sensor for collecting DC side voltage, and a power generation control unit for reducing the DC side voltage fluctuation under a constant power load while reducing the impact on the DC side voltage dynamic performance. The composite load current compensation strategy in the control method provided by the present invention can reduce the DC side voltage fluctuation while reducing the impact on the DC side voltage dynamic performance; in addition, in the control method, fuzzy control is used to adjust the compensation coefficient of the q-axis voltage and q-axis current compensator online, which can reduce the dependence on system parameters and reduce the DC side voltage fluctuation within the full operating range.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation systems, and in particular to a permanent magnet generator system capable of stably operating under a constant power load and a control method thereof. Background Art

[0002] More-electric / all-electric aircraft use electrical energy to partially or completely replace air pressure energy, hydraulic energy, and mechanical energy, which reduces carbon dioxide emissions and improves energy efficiency. It is an important way to develop aviation electrification. More-electric aircraft high-voltage DC electrical loads are divided into linear and non-linear loads. Linear loads are resistive loads, and their voltage and current are linearly related and easy to control. The characteristics of non-linear loads mainly include energy feedback, constant power characteristics, and pulse power characteristics. The speed control motors, electric actuators, and DC / DC converters used in more-electric aircraft appear as constant power loads, that is, the average power is basically unchanged, and the voltage and current are nonlinearly inversely proportional.

[0003] Compared with large industrial power grids, the capacity of the power supply system of multi-electric aircraft is limited. The constant power load has a great impact on the stability of the DC power grid, and it is easy to cause the DC bus voltage and current to jitter or even diverge.

[0004] The stability problem under constant power load has become one of the urgent issues to be solved in airborne power systems. Summary of the invention

[0005] The main purpose of the present invention is to provide a permanent magnet generator system and a control method thereof that can operate stably under a constant power load, so as to overcome the influence of the prior art on the dynamic performance of the DC side voltage of the power generation system and the problem that the DC side voltage fluctuation cannot be reduced under a constant power load within the full operating range of the power generation system.

[0006] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0007] A permanent magnet generator system capable of stably operating under a constant power load, comprising an engine, a permanent magnet generator, a rotary transformer for collecting motor rotor position signals, a three-phase full-bridge main power circuit, a current sensor for collecting motor three-phase armature winding currents, a constant power load, a voltage sensor for collecting DC side voltage, and a power generation control unit for reducing the DC side voltage fluctuation under a constant power load while reducing the impact on the dynamic performance of the DC side voltage;

[0008] The power generation control unit includes a composite load current compensator, which includes a q-axis voltage compensator and a q-axis current compensator, wherein the q-axis voltage compensator is used to output a q-axis voltage compensation value, and the q-axis current compensator is used to output a q-axis current compensation value;

[0009] The q-axis voltage compensator and q-axis current compensator are composed of a low-pass filter and a compensation coefficient.

[0010] A control method for a permanent magnet generator system capable of stably operating under a constant power load comprises the following steps:

[0011] Step 1: Convert the three-phase AC power in the system into DC power through a three-phase full-bridge main power circuit to provide energy for a constant power load;

[0012] Step 2: The power generation control unit implements voltage stabilization control according to the variables detected for the constant power load, and simultaneously completes the fuzzy adaptive composite load current compensation strategy;

[0013] Step 2 is as follows:

[0014] The compensation coefficient of the composite load current compensator is adjusted by fuzzy control, and the output of the composite load current compensator is compensated to the q-axis voltage instruction and the q-axis current instruction respectively;

[0015] The inputs of fuzzy control are the error between DC side voltage command and DC side voltage feedback, the variation of DC side voltage error, load current and load current variation.

[0016] The outputs of the fuzzy control are the compensation coefficient changes of the q-axis voltage compensator and the compensation coefficient changes of the q-axis current compensator.

[0017] Preferably, the current DC side voltage error e udc (k) Subtract the DC voltage error e of the previous Td cycles udc (k-Td) gets the DC side voltage error change,

[0018] Through the current load current i L (k) minus the load current i of the previous Td cycles L (k-Td) gets the load current change.

[0019] Preferably, the power generation control unit adopts double closed-loop control, the outer loop is a voltage loop, and the inner loop is a current loop, and the actually detected DC side voltage is compared with the DC voltage command value, and a quadrature axis current command value is generated through a voltage regulator;

[0020] The current in the three-phase stationary coordinate system is transformed into the current in the two-phase rotating coordinate system through coordinate transformation, and compared with the quadrature and direct axis current command values ​​respectively. The corresponding differences are passed through the current regulator to obtain the quadrature and direct axis voltage command values ​​respectively.

[0021] Finally, the driving signal of the switch tube is generated through the space voltage vector modulation strategy to maintain the stability of the DC side output voltage.

[0022] Preferably, the composite load current compensator outputs the compensation coefficient variation Δk of the q-axis current compensator through fuzzy control. LPF1 and the compensation coefficient change of the q-axis voltage compensator Δk LPF2 ;

[0023] The q-axis current compensator outputs the quadrature-axis current compensation value, and the q-axis voltage compensator outputs the voltage compensation value, i.e., Δi qcmp and Δu qcmp ;

[0024] Composite load current compensation can increase the damping of the power generation system, reduce the DC side voltage fluctuation and reduce the impact on the DC side voltage dynamic performance;

[0025] The input of fuzzy control is the error between DC voltage command and DC voltage feedback. udc , error change Δe udc , load current i L , and the load current change Δi L ,Fuzzy control outputs the change of compensation coefficient through the changes of these quantities and the design of fuzzy rules.

[0026] Preferably, the fuzzy rules of fuzzy control are as follows:

[0027] When Δi L When the absolute value of becomes larger, increase Δk LPF1 , increasing Δk LPF2 ;

[0028] When Δi L As the absolute value of becomes smaller, reduce Δk LPF1 , reduce Δk LPF2 ;

[0029] When e udc The absolute value of Δe becomes larger and udc When the absolute value of becomes larger, reduce Δk LPF1 , reduce Δk LPF2 ;

[0030] When Δe udc As the absolute value of becomes smaller, Δk LPF1 unchanged, Δk LPF2 constant.

[0031] Preferably, before step 1, the method further includes: causing the engine to drive the permanent magnet generator to rotate to generate three-phase AC power.

[0032] Beneficial technical effects of the present invention:

[0033] The composite load current compensation strategy in the control method provided by the present invention can reduce the DC side voltage fluctuation while reducing the impact on the dynamic performance of the DC side voltage; in addition, in the control method, fuzzy control is used to adjust the compensation coefficients of the q-axis voltage and q-axis current compensators online, which can reduce the dependence on system parameters and reduce the DC side voltage fluctuation within the full operating range. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of a permanent magnet generator system for reducing DC side voltage fluctuation according to an embodiment of the present invention;

[0035] Figure 2 is a schematic diagram of a power generation control unit according to an embodiment of the present invention;

[0036] Figure 3 It is a schematic diagram of the principle of a fuzzy adaptive composite load current compensator according to an embodiment of the present invention.

[0037] Explanation of the symbols in the figure: T1, T2, T3, T4, T5, T6 are switch tubes with anti-parallel diodes, C1 is the DC side filter capacitor, H a , H b , H c , H L It is a Hall current sensor;

[0038] i a 、i b 、i c is the three-phase armature current, θ is the rotor position angle, i L is the load current, U dcfdb is the measured DC side voltage, U dcref is the DC side voltage command value;

[0039] i qfdb 、i dfdb is the AC and DC axis current in the three-phase winding, i qref 、i dref is the quadrature and direct axis current command value after compensation, i qrefpre is the quadrature-axis current command before compensation;

[0040] U q , U d is the AC and DC axis voltage command of the three-phase winding after compensation, U qpre is the quadrature axis voltage before compensation;

[0041] Δi qcmp and Δu qcmp are the quadrature-axis current and quadrature-axis voltage compensation values ​​respectively;

[0042] Δi q and Δi dare the quadrature-axis current and direct-axis current errors respectively;

[0043] e udc is the error between the DC side voltage command and the DC side voltage feedback, Δe udc is the error variation;

[0044] Δi L is the load current change, z -Td It is a delay link, delaying Td sampling cycles;

[0045] Δk LPF1 is the change in the compensation coefficient of the q-axis current compensator, Δk LPF2 is the change in the compensation coefficient of the voltage compensator. DETAILED DESCRIPTION

[0046] In order to make the technical solution of the present invention more clear and specific to those skilled in the art, the present invention is further described in detail below in conjunction with embodiments and drawings, but the implementation manner of the present invention is not limited thereto.

[0047] like Figure 1-Figure 3 As shown, the permanent magnet generator system provided by this embodiment can stably operate under constant power load, including an engine, a permanent magnet generator, a rotary transformer for collecting motor rotor position signals, a three-phase full-bridge main power circuit, a current sensor for collecting motor three-phase armature winding currents, a constant power load, a voltage sensor for collecting DC side voltage, and a power generation control unit for reducing the DC side voltage fluctuation under constant power load while reducing the impact on the dynamic performance of the DC side voltage.

[0048] The power generation control unit includes a composite load current compensator,

[0049] The composite load current compensator includes a q-axis voltage compensator and a q-axis current compensator.

[0050] The q-axis voltage compensator outputs the q-axis voltage compensation value, and the q-axis current compensator outputs the q-axis current compensation value.

[0051] The q-axis voltage compensator and the q-axis current compensator are both composed of a low-pass filter and a compensation coefficient.

[0052] A control method for a permanent magnet generator system capable of stably operating under a constant power load comprises the following steps:

[0053] In this system, the engine drives the permanent magnet generator to generate three-phase AC power;

[0054] Step 1: Convert three-phase AC power into DC power through a three-phase full-bridge main power circuit to provide energy for a constant power load;

[0055] Step 2: The power generation control unit implements voltage stabilization control according to the variables detected for the constant power load, and simultaneously completes the fuzzy adaptive composite load current compensation strategy;

[0056] Step 2 is as follows:

[0057] The compensation coefficient of the composite load current compensator is adjusted by fuzzy control. The output of the composite load current compensator is compensated to the q-axis voltage command and the q-axis current command respectively. By increasing the damping of the power generation system, the DC side voltage fluctuation within the full operating range under constant power load is reduced.

[0058] The power generation control unit adopts double closed-loop control, with the outer loop being the voltage loop and the inner loop being the current loop. The actual detected DC side voltage is compared with the DC voltage command value (DC voltage command value minus the actual detected DC side voltage), and the difference is passed through the voltage regulator to generate the quadrature axis current command value.

[0059] The current in the three-phase stationary coordinate system is transformed into the current in the two-phase rotating coordinate system by coordinate transformation, and the current in the phase rotating coordinate system is compared with the quadrature and direct axis current command values, and the corresponding differences are passed through the current regulator to obtain the quadrature and direct axis voltage command values;

[0060] Finally, the driving signal of the switch tube is generated through the space voltage vector modulation strategy to maintain the stability of the DC side output voltage;

[0061] The inputs of fuzzy control are the error between DC side voltage command and DC side voltage feedback, the variation of DC side voltage error, load current and load current variation.

[0062] The outputs of the fuzzy control are the compensation coefficient changes of the q-axis voltage compensator and the compensation coefficient changes of the q-axis current compensator.

[0063] In this embodiment, the current DC side voltage error e udc (k) Subtract the DC voltage error e of the previous Td cycles udc (k-Td) gets the DC side voltage error change.

[0064] In this embodiment, the current load current i L (k) minus the load current i of the previous Td cycles L (k-Td) gets the load current change.

[0065] In this embodiment, the fuzzy adaptive composite load current compensator outputs the compensation coefficient change Δk of the q-axis current compensator through fuzzy control. LPF1 and the compensation coefficient change of the q-axis voltage compensator Δk LPF2 ;

[0066] The q-axis current compensator outputs the quadrature-axis current compensation value, and the q-axis voltage compensator outputs the voltage compensation value, i.e., Δi qcmp and Δu qcmp ;

[0067] Composite load current compensation can increase the damping of the power generation system, reduce the DC side voltage fluctuation and reduce the impact on the DC side voltage dynamic performance;

[0068] The input of fuzzy control is the error between DC voltage command and DC voltage feedback. udc , error change Δe udc , load current i L , and the load current change Δi L ,Fuzzy control outputs the change of compensation coefficient through the changes of these quantities and the design of fuzzy rules.

[0069] The fuzzy rules are designed as follows:

[0070] When Δi L When the absolute value of becomes larger, increase Δk LPF1 , increasing Δk LPF2 ;

[0071] When Δi L As the absolute value of becomes smaller, reduce Δk LPF1 , reduce Δk LPF2 ;

[0072] When e udc The absolute value of Δe becomes larger and udc When the absolute value of becomes larger, reduce Δk LPF1 , reduce Δk LPF2 ;

[0073] When Δe udc As the absolute value of becomes smaller, Δk LPF1 unchanged, Δk LPF2 constant.

[0074] In this embodiment, the q-axis voltage compensator has a limited damping degree, while the q-axis current compensator can provide strong damping but reduces the dynamic performance of the DC side voltage. The combination of the q-axis voltage compensator and the q-axis current compensator can reduce the DC side voltage fluctuation under constant power load while reducing the impact on the dynamic performance of the DC side voltage.

[0075] To sum up, in this embodiment, the composite load current compensation strategy in the control method provided in this embodiment can reduce the DC side voltage fluctuation while reducing the impact on the dynamic performance of the DC side voltage; in addition, in this control method, fuzzy control is used to online adjust the compensation coefficients of the q-axis voltage and q-axis current compensators, which can reduce the dependence on system parameters and reduce the DC side voltage fluctuation within the full operating range.

[0076] The above description is only a further embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the scope disclosed by the present invention, which belong to the protection scope of the present invention.

Claims

1. A control method for a permanent magnet generator system capable of stably operating under a constant power load, the permanent magnet generator system capable of stably operating under a constant power load comprising an engine, a permanent magnet generator, a rotary transformer for collecting a motor rotor position signal, a three-phase full-bridge main power circuit, a current sensor for collecting a three-phase armature winding current of the motor, a constant power load, a voltage sensor for collecting a DC side voltage, and a power generation control unit for reducing the influence on the dynamic performance of the DC side voltage while reducing the DC side voltage fluctuation under a constant power load; The power generation control unit includes a composite load current compensator, and the composite load current compensator includes q Shaft voltage compensator and q Shaft current compensator, where q Shaft voltage compensator for output q Shaft voltage compensation value, q Shaft current compensator for output q Shaft current compensation value; Said q Shaft voltage compensator and q The shaft current compensator is composed of a low-pass filter and a compensation coefficient; It is characterized in that The following steps are included Step 1: Convert the three-phase AC power in the system into DC power through a three-phase full-bridge main power circuit to provide energy for a constant power load; Step 2: The power generation control unit implements voltage stabilization control according to the variables detected for the constant power load, and simultaneously completes the fuzzy adaptive composite load current compensation strategy; The step 2 is specifically as follows: The compensation coefficient of the composite load current compensator is adjusted by fuzzy control, and the output of the composite load current compensator is compensated to q The shaft voltage command and q Axis current command place; The inputs of the fuzzy control are respectively the error between the DC side voltage command and the DC side voltage feedback, the DC side voltage error variation, the load current and the load current variation; The outputs of the fuzzy control are q The compensation coefficient change of the shaft voltage compensator and q Change in the compensation coefficient of the shaft current compensator.

2. The control method of the permanent magnet generator system capable of stably operating under constant power load according to claim 1 is characterized in that: By the current DC side voltage error e udc ( k ) minus the previous Td DC voltage error per cycle e udc ( k-Td ) to obtain the DC side voltage error change.

3. The control method of the permanent magnet generator system capable of stably operating under constant power load according to claim 1, characterized in that: Through the current load current i L ( k ) minus the previous Td Load current per cycle i L ( k-Td ) to obtain the load current change.

4. The control method of the permanent magnet generator system capable of stably operating under constant power load according to claim 1, characterized in that: The power generation control unit adopts double closed-loop control, with the outer loop being the voltage loop and the inner loop being the current loop. The actual detected DC side voltage is compared with the DC voltage command value, and after passing through the voltage regulator, a quadrature axis current command value is generated. The current in the three-phase stationary coordinate system is transformed into the current in the two-phase rotating coordinate system through coordinate transformation, and compared with the quadrature and direct axis current command values ​​respectively. The corresponding differences are passed through the current regulator to obtain the quadrature and direct axis voltage command values ​​respectively. Finally, the driving signal of the switch tube is generated through the space voltage vector modulation strategy to maintain the stability of the DC side output voltage.

5. The control method of the permanent magnet generator system capable of stably operating under constant power load according to claim 1, characterized in that: The composite load current compensator outputs q Change of compensation coefficient of shaft current compensator ∆ k LPF1 and q Change of shaft voltage compensator compensation coefficient ∆ k LPF2 ; Said q The axis current compensator outputs the quadrature axis current compensation value, q The shaft voltage compensator outputs the voltage compensation value, that is, ∆ i qcmp and ∆ u qcmp ; The input of fuzzy control is the error between DC voltage command and DC voltage feedback. e udc 、 Error change ∆ e udc 、 Load current i L 、 And the load current change ∆ i L ,Fuzzy control outputs the change of compensation coefficient through the changes of these quantities and the design of fuzzy rules.

6. The control method of the permanent magnet generator system capable of stably operating under constant power load according to claim 5, characterized in that: The fuzzy rules of the fuzzy control are as follows: When ∆ i L When the absolute value of becomes larger, increase ∆ k LPF1 , increase ∆ k LPF2 ; When ∆ i L As the absolute value of k LPF1 , reduce ∆ k LPF2 ; when e udc The absolute value of ∆ e udc When the absolute value of becomes larger, reduce ∆ k LPF1 , reduce ∆ LPF 2; When ∆ e udc As the absolute value of ∆ k LPF1 unchanged, ∆ k LPF2 constant.

7. The control method of a permanent magnet generator system capable of stably operating under a constant power load according to claim 1, characterized in that: Before step 1, the method further includes: causing the engine to drive the permanent magnet generator to rotate to generate three-phase AC power in the system.

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