Electro-magnetic doubly salient generator voltage regulation strategy based on cooperative control of exciting current and armature current

Abstract

The invention discloses an electro-magnetic doubly salient generator voltage regulation strategy based on cooperative control of excitation current and armature current. According to the invention, the doubly salient electro-magnetic motor can always work at the minimum copper loss point during power generation operation, and the copper loss of a power generation system is reduced. And meanwhile, the armature current inner ring is used for replacing the exciting current inner ring, so that the dynamic performance of the power generation system is optimized. The method comprises the following steps of: off-line acquiring a combination of exciting current and armature current under different rotating speeds and loads under the same output voltage, calculating the copper loss based on the acquired combination of exciting current and armature current, and establishing a copper loss optimal exciting current analytic expression through data fitting. And taking the voltage outer loop output as a q-axis current reference value, and obtaining a reference value of the excitation current under the current working condition through a copper loss optimal excitation current analytic formula in combination with the rotating speed and the output power of the motor at the moment. And a three-phase current reference value is obtained by combining real-time rotor position information and a q-axis current reference value, and closed-loop control of armature current is realized through a controllable rectifier. And closed-loop control of the excitation current is realized through an asymmetric half-bridge circuit by combining the excitation current reference value and the actual excitation current.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and in particular to a voltage regulation strategy for an electrically excited double-salient-pole generator based on coordinated control of an excitation current and an armature current. Background Art

[0002] The electrically excited double-salient-pole motor is a new type of reluctance motor developed on the basis of the switched reluctance motor. Both the stator and the rotor are salient structures. The armature winding and the excitation winding are wound on the stator poles, and there are no permanent magnets and windings on the rotor. It has the advantages of simple and reliable structure and suitable for operation under complex working conditions. When generating electricity, an uncontrolled rectifier topology is generally used as the external circuit to form a brushless DC power generation system. The voltage-stabilized output can be achieved by adjusting the excitation current, without the need for a position sensor, and has the advantages of simple and reliable control.

[0003] Compared with the uncontrolled rectifier power generation topology, the controlled rectifier power generation topology introduces active regulation of the armature current, which can significantly improve the output power of the electrically excited double-pole generator. After searching, the Chinese patent application number CN202311302405.6 discloses a back-EMF directional vector control strategy for an electrically excited double-pole generator, which improves the output power of the electrically excited double-pole generator compared to the uncontrolled rectifier power generation method. In the controlled rectifier power generation system, due to the introduction of active regulation of the armature current, there are multiple combinations of armature current and excitation current during voltage stabilization output, and the copper loss of the power generation system is inconsistent under different combinations. There is a combination that minimizes the copper loss of the power generation system. In addition, in the uncontrolled rectifier power generation system, due to the uncontrollability of the armature current, the excitation current can only be adjusted to adapt to changes in working conditions. There is a problem of poor dynamic performance due to the large self-inductance of the excitation winding, while in the controlled rectifier power generation system, the dynamic response of the system can be accelerated by adjusting the armature current. Summary of the invention

[0004] The present invention can adjust the excitation current and the armature current in real time according to the actual operating conditions of the motor when the electrically excited double-salient-pole generator is running, effectively reducing the copper loss of the power generation system and optimizing the dynamic response of the power generation system.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] S1. According to the operating conditions of the electrically excited double-pole generator, combined with the analytical formula of the optimal excitation current for copper loss, determine the excitation current reference value i of the electrically excited double-pole generator when the copper loss is the minimum under the current operating conditions. f_ref At the same time, the double closed-loop control strategy of voltage outer loop + armature current inner loop is used to determine the q-axis current reference value i q_ref .

[0007] S2. According to the q-axis current reference value i q_refThe actual armature current controls the switch tube in the controlled rectifier through the hysteresis comparator, and the excitation current reference value i f_ref The actual excitation current is controlled by a PI regulator to control the switch tube in the asymmetric half-bridge circuit.

[0008] Furthermore, the optimal excitation current analytical formula for copper loss is established using the following method:

[0009] S1.1, according to the motor running speed, output power range, under the premise of the same output voltage, at speeds n1, n2...n j And the output power is P o1 , P o2 …P ok Get different excitation currents i under j×k working conditions f The armature current i p The combination of f11_1 ,i p11_1 )、(i f11_2 ,i p11_2 )…(i f11_m ,i p11_m )…(i fjk_1 ,i pjk_1 )、(i fjk_2 ,i pjk_2 )…(i fjk_m ,i pjk_m ).

[0010] S1.2, according to the combination of excitation current and armature current under different working conditions obtained in step S1.1, calculate the total copper loss under each combination, and use the excitation current corresponding to the minimum copper loss point under different working conditions as a sample to perform data fitting to obtain the total copper loss under different working conditions. o The optimal excitation current analytical formula for copper loss with independent variable i f_ref =f(n,P o ).

[0011] The step S2 performs closed-loop control on the armature current and the excitation current, and the specific steps are as follows:

[0012] S2.1, close-loop control of the armature current, using the q-axis current reference value i q_ref The reference value of the three-phase current is obtained by inverse Park transformation with the current vector position, and is input into the hysteresis comparator after subtracting it from the actual three-phase current, and the output is used as the driving signal of each switch tube of the controlled rectifier.

[0013] S2.2, close the loop control of the excitation current and set the excitation current reference value i f_ref The difference between the actual excitation current and the output is input to the PI regulator, and the output is used as the drive signal for the upper tube of the left bridge arm of the asymmetric half-bridge converter. The lower tube of the right bridge arm is normally open.

[0014] The current vector position in step S2.1 is specifically as follows:

[0015] S2.1.1. Obtain the three-way back EMF of the electrically excited doubly salient-pole generator offline, and obtain the position of the back EMF vector corresponding to the rotor position through inverse tangent calculation. The current vector position leads the back EMF vector position by 180°.

[0016] The beneficial effects of the present invention are as follows:

[0017] The present invention fully determines the reference values ​​of the excitation current and the armature current based on the operating conditions of the electrically excited double-salient-pole generator, and controls the switch tubes of the controllable rectifier and the asymmetric half-bridge circuit based on the reference values, thereby effectively reducing the total copper loss of the power generation system and optimizing the efficiency of the power generation system.

[0018] The present invention also adopts an armature current inner loop to replace the excitation current inner loop, making full use of the characteristic of small time constant of the armature winding and effectively improving the dynamic performance of the electrically excited double-salient-pole generator.

[0019] The present invention has universality and can be widely applied to other electric excitation motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the excitation current-armature current curve of the electrically excited double-salient-pole generator at different output powers;

[0021] Figure 2 This is the voltage outer loop-excitation current inner loop voltage regulation strategy block diagram

[0022] Figure 3 It is the copper loss cloud diagram of the electrically excited double-salient-pole generator under different speeds and load conditions;

[0023] Figure 4 It is the excitation current at the point where the copper loss is minimum under different speeds and load conditions of the electrically excited doubly salient-pole generator;

[0024] Figure 5 It is a block diagram of the voltage regulation strategy of the electrically excited double-salient-pole generator proposed in the present invention;

[0025] Figure 6 The copper loss experiment is compared between the voltage outer loop-excitation current inner loop strategy and the voltage regulation method proposed in the present invention.

[0026] Figure 7 The voltage outer loop-excitation current inner loop strategy is used to compare the voltage regulation method proposed in the present invention with the loading experiment.

[0027] Figure 8 The unloading experiment is compared between the voltage outer loop-excitation current inner loop strategy and the voltage regulation method proposed in the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings:

[0029] The present invention may be implemented in many different forms and should not be considered limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0030] Embodiment 1:

[0031] An embodiment of the present invention provides a voltage regulation method for an electrically excited double-salient-pole generator. Figure 1 The figure shows the combination of different excitation current and armature current when an electrically excited double-salient-pole generator outputs 110V DC voltage at a constant speed and different output powers. It can be seen that when the load changes, the traditional voltage outer loop-excitation current inner loop strategy cannot work at the minimum copper loss point under every working condition. In addition, due to the large self-inductance of the excitation winding, the time constant of the excitation current inner loop is large, and the dynamic performance of the system is poor.

[0032] According to the motor running speed and output power range, under the premise of outputting 110V DC voltage, the speeds n1, n2…n j And the output power is P o1 , P o2 …P ok Get different excitation currents i under j×k working conditions f The armature current i p The combination of f11_1 ,i p11_1 )、(i f11_ 2, i p11_2 )…(i f11_m ,i p11_m )…(i fjk_1 ,i pjk_1 )、(i fjk_2 ,i pjk_2 )…(i fjk_m ,i pjk_m ). Figure 2 The following is a cloud diagram of the copper loss of the system under different speeds, different output powers, and different excitation currents when outputting 110V DC voltage. The excitation current at the point where the copper loss is minimum is affected by both the speed and the output power. Figure 2 The excitation current at the point where the copper loss is the minimum in each cloud diagram is drawn as a cloud diagram as follows Figure 3 As shown, the data is fitted to obtain the optimal excitation current analytical formula i for copper loss with speed n and output power Po as independent variables. f_ref =f(n,P o ).

[0033] Figure 5 The figure shows the block diagram of the voltage regulation strategy of the electrically excited double-salient-pole generator proposed in the present invention. In order to solve the problem of poor dynamic performance caused by large self-inductance of the excitation winding, the method proposed in the present invention replaces the excitation current inner loop with the armature current inner loop. The actual voltage is input into the PI regulator after the difference between the actual voltage and the reference voltage, and the output of the PI regulator is used as the q-axis current control quantity i q_ref According to the obtained i q_ref The switch tube of the controlled rectifier is controlled by the real-time rotor position information. At the same time, the excitation current is given according to the speed and the calculated instantaneous output power based on the copper loss optimal excitation current analytical formula. f_ref , and then input into the PI regulator after subtracting it from the actual excitation current, and the output is used as the driving signal of the upper tube of the left bridge arm of the asymmetric half-bridge circuit to realize closed-loop control of the excitation current.

[0034] Figure 6 The copper loss experiment of the motor using the voltage outer loop-excitation current inner loop strategy and the controllable rectification method proposed in the present invention is compared. It can be seen that under all working conditions, it is proved that the method proposed in the present invention can effectively reduce the copper loss of the electrically excited double-salient-pole generator.

[0035] Figure 7 and Figure 8 The loading and unloading experiments using the voltage outer loop-excitation current inner loop strategy and the voltage regulation method proposed in the present invention are compared. It can be seen that during the load mutation process, compared with the voltage outer loop-excitation current inner loop strategy, the proposed strategy can effectively reduce the voltage mutation during the load mutation process and accelerate the recovery time of the dynamic process.

[0036] The beneficial effects of the present invention are as follows: the present invention strictly limits the operating conditions of the electrically excited double-pole generator to the point of minimum copper loss, replaces the inner loop of the excitation current with the inner loop of the armature current on the basis of the voltage outer loop and the excitation current inner loop control strategy, and controls the excitation current according to the analytical formula of the optimal excitation current for copper loss. Compared with the voltage outer loop and the excitation current inner loop control strategy, the copper loss is effectively reduced and the dynamic performance of the power generation system is optimized.

[0037] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0038] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method 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 in the scope of protection of the present invention.

Claims

1. A voltage regulation strategy for an electrically excited doubly salient-pole generator based on coordinated control of excitation current and armature current, characterized in that: The following steps are involved: S1. According to the operating conditions of the electrically excited double-pole generator, combined with the analytical formula of the optimal excitation current for copper loss, determine the excitation current reference value i of the electrically excited double-pole generator when the copper loss is the minimum under the current operating conditions. f_ref At the same time, a double closed-loop control strategy of voltage outer loop and armature current inner loop is used to determine the q-axis current reference value i q_ref . S2. According to the q-axis current reference value i q_ref The actual armature current controls the switch tube in the controlled rectifier through the hysteresis comparator, and the excitation current reference value i f_ref The actual excitation current is controlled by a PI regulator to control the switch tube in the asymmetric half-bridge circuit. Furthermore, the optimal excitation current analytical formula for copper loss is established using the following method: S1.1, according to the motor running speed, output power range, under the premise of the same output voltage, at speeds n1, n2...n j And the output power is P o1 , P o2 …P ok Get different excitation currents i under j×k working conditions f The armature current i p The combination of f11_1 ,i p11_1 )、(i f11_2 ,i p11_2 )…(i f11_m ,i p11_m )…(i fjk_1 ,i pjk_1 )、(i fjk_2 ,i pjk_2 )…(i fjk_m ,i pjk_m ). S1.2, according to the combination of excitation current and armature current under different working conditions obtained in step S1.1, calculate the total copper loss under each combination, and use the excitation current corresponding to the minimum copper loss point under different working conditions as a sample to perform data fitting to obtain the total copper loss under different working conditions. o The optimal excitation current analytical formula for copper loss with independent variable i f_ref =f(n,P o ). The step S2 performs closed-loop control on the armature current and the excitation current, and the specific steps are as follows: S2.1, close-loop control of the armature current, using the q-axis current reference value i q_ref The reference value of the three-phase current is obtained by inverse Park transformation with the current vector position, and the reference value is input into the hysteresis comparator after being subtracted from the actual three-phase current, and the output is used as the driving signal of each switch tube of the controlled rectifier. S2.2, close the loop control of the excitation current and set the excitation current reference value i f_ref The difference between the actual excitation current and the input is to the PI regulator, and the output is used as the drive signal for the upper tube of the left bridge arm of the asymmetric half-bridge converter, and the lower tube of the right bridge arm is normally open. The current vector position in step S2.1 is specifically as follows: S2.1.

1. Obtain the three-way back EMF of the electrically excited doubly salient-pole generator offline, and obtain the position of the back EMF vector corresponding to the rotor position through inverse tangent calculation. The current vector position leads the back EMF vector position by 180°.

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