Permanent magnet synchronous generator parallel control device and method

Abstract

The invention provides a permanent magnet synchronous generator parallel control device and method. The device adopts the scheme that the permanent magnet synchronous generator is connected with the controllable rectification direct current side in parallel, eddy current loss of the generator is reduced, and output voltage is improved. According to the output current of each module circuit, the current disturbance coefficient is dynamically adjusted, the given value of the direct current output voltage is dynamically adjusted, the control precision of the parallel current is improved, the problems of circulating current generated by parallel operation of the generator and unbalanced output current are solved, and high power, modularization and modularization of the permanent magnet synchronous generator are realized. Meanwhile, iq after coordinate transformation is adopted as feedback quantity, direct current measurement is not needed, the number of current sensors is reduced, the product cost is reduced, an additional synchronizing device is not needed, and the size, the weight and the complexity of the system are reduced.

Description

Technical Field

[0001] The invention belongs to the field of generator control, and in particular relates to a permanent magnet synchronous generator parallel control device and method. Background Art

[0002] Traditional generators are mostly diesel generators, wind power double-fed generators or three-stage excitation generators for aviation. In recent years, with the development and application of new power electronics technology, permanent magnet synchronous generators have gradually increased their applications in some occasions with high weight and volume requirements such as aviation and aerospace due to their advantages of high power density and high efficiency, with power levels ranging from kW to tens of kW. Limited by factors such as installation space, volume, and weight, a single generator cannot meet the power demand of high-power loads. The existing generator parallel control methods mainly include direct parallel connection on the AC side, adjusting the excitation current to achieve generator parallel connection, and adjusting the generator speed to achieve generator parallel connection. There are problems such as poor operating effect, large generator loss, and increased system volume, weight, and complexity. For example, the invention patent "A parallel circuit of AC generators" (CN104319804A) uses a parallel control module to adjust the reference voltage and the proportional coefficient of the proportional link to adjust the generator excitation current, and then adjust the output voltage of the main generator and the slave generator to achieve generator parallel control. The excitation generator requires equipment such as an excitation controller, which increases the system volume, weight, and complexity of the control system. The invention patent "A Diesel Generator Parallel Control Device" (CN105071432B) is a direct parallel connection of the generator AC side, which requires the generator voltage frequency, amplitude, phase, and phase sequence to be completely consistent, otherwise it will generate a large circulating current, affecting the motor's forward operation, or even burning the motor. At the same time, the parallel current is affected by external factors such as line impedance, and the effect is not good. The paper "Research on Distributed Permanent Magnet Generator Voltage Stabilized Power Supply Based on Prime Mover Speed ​​Regulation" (doctoral dissertation, Shenyang University of Technology, He Gongfei) uses permanent magnet synchronous generators in parallel, and realizes generator parallel control by adjusting the generator speed. The rectifier circuit is an uncontrolled rectifier bridge composed of diodes. The uncontrolled rectifier circuit will significantly increase the eddy current loss of the generator, reduce the output voltage, increase the voltage regulation rate, and reduce the performance of the power generation system.

[0003] In order to realize the modularization, building block and high power of permanent magnet synchronous generators, an efficient permanent magnet synchronous generator parallel control device and method are urgently needed. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art, and to provide a permanent magnet synchronous generator parallel control device and method, which adopts a solution of connecting a permanent magnet synchronous generator in parallel with a controllable rectifier DC side, reduces the eddy current loss of the generator, and improves the output voltage. The current disturbance coefficient is dynamically adjusted according to the output current of each module circuit, and the given value of the DC output voltage is dynamically adjusted to improve the control accuracy of the parallel current, solve the problem of circulating current and output current imbalance caused by parallel operation of the generator, and realize the high-power, modularization and modularization of the permanent magnet synchronous generator. At the same time, by using iq as the feedback quantity, there is no need to collect DC current measurement, which reduces the number of current sensors, reduces the product cost, does not require additional synchronization devices, and reduces the volume, weight and complexity of the system.

[0005] The invention provides a permanent magnet synchronous generator parallel control device. The generator parallel control device comprises module circuit 1, module circuit 2 ... module circuit n, each module circuit corresponds to a permanent magnet synchronous generator, converts the alternating current generated by the generator into direct current, the direct current side of each rectifier module is connected together, and each module is connected through a CAN bus to transmit data.

[0006] The module circuit includes an IGBT module, a high-power diode, and an IGBT absorption capacitor. The output of the IGBT module is filtered by the IGBT absorption capacitor and then connected in series with a high-power diode. The output end of each module is connected to a common capacitor to supply power to various loads at the back end.

[0007] The present invention also provides a method for controlling a permanent magnet synchronous generator in parallel, wherein the difference between the module circuit iq and the average value of the iq of each module circuit is used as an error amount, and after passing through a PI regulator, a disturbance amount of the current coefficient is obtained, and the total disturbance amount of the current coefficient is obtained by superimposing the initial disturbance coefficient, and the disturbance amount is multiplied by iq as the disturbance amount of the DC voltage outer loop reference value. When there is a deviation in the output current of the generator, the PI regulator will continuously adjust the above disturbance amount until the iq deviation is eliminated, thereby achieving the effect of consistent output current of the generator.

[0008] Since iq can directly reflect the output current parameters of the generator, iq is used as the calculation factor of the disturbance quantity. There is no need to collect the DC output current of the generator, which avoids adding current sensors on the DC side, reduces system complexity and saves costs.

[0009] The beneficial effects of the present invention are as follows:

[0010] 1. The present invention dynamically adjusts the current disturbance coefficient until the generator output current is consistent and is not affected by external factors such as line impedance;

[0011] 2. The present invention does not require additional synchronization devices, reducing the volume, weight and complexity of the system;

[0012] 3. The present invention adopts the output of the PI regulator as the proportional coefficient for adjusting the disturbance current, which can improve the control accuracy of the parallel current and reduce the fluctuation of the DC output voltage;

[0013] 4. The invention connects a high-power diode in series on the DC side of each generator, which fundamentally solves the problem of generator circulation;

[0014] 5. The present invention uses iq in the control system as the disturbance current, and does not need to collect DC current measurement, thus saving DC side current sensors and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the control device of the present invention;

[0016] Figure 2 It is a schematic diagram of the control method principle of the present invention. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0018] The present invention provides a permanent magnet synchronous generator parallel control device, the circuit is as follows Figure 1 As shown, the device includes: module circuit 1, module circuit 2, ... module circuit n, and common capacitor 3; module circuit 1 corresponds to permanent magnet synchronous generator 1, module circuit 2 corresponds to permanent magnet synchronous generator 2, and module circuit n corresponds to permanent magnet synchronous generator n. The connection relationship between the power end of module circuit 1, module circuit 2, ... module circuit n is: the DC output is connected to the common filter capacitor 3, capacitor 3 is a film capacitor with strong peak current capability, the capacitance is greater than 2000uF, and the withstand voltage is greater than 400V, and the filter capacitor is connected to the load. The connection relationship between the control end of module circuit 1, module circuit 2, and module circuit n is: the module circuits are connected through the CAN bus.

[0019] Take module circuit 1 as an example. Figure 1The module circuit includes an IGBT module 1, a diode 1, a capacitor 1, a sampling module 1, a driving module 1, a resolver decoding module 1, and a main control chip 1. The input end of the IGBT module 1 is connected to the three-phase output end of the permanent magnet synchronous generator 1, the positive output end of the IGBT module 1 is connected to the positive electrode of the diode 1 and the positive electrode of the capacitor 1, the negative electrode of the diode 1 is connected to the positive electrode of the capacitor 3, and the negative output end of the IGBT module 1 is connected to the negative electrode of the capacitor 1 and the negative electrode of the capacitor 3. The input end of the sampling module 1 is connected to the three-phase output end of the permanent magnet synchronous generator 1 and the capacitor 1, the output end of the sampling module 1 is connected to the main control chip 1, the input end of the driving module 1 is connected to the main control chip 1, the output end of the driving module 1 is connected to the IGBT module 1, the input end of the resolver decoding module 1 is connected to the resolver 1 of the permanent magnet synchronous generator 1, the output end of the resolver decoding module 1 is connected to the main control chip 1, the input end of the CAN communication module 1 is connected to the main control chip 1, and the output end of the CAN communication module 1 is connected to the CAN bus and the CAN communication module 2...CAN communication module n.

[0020] The present invention also provides another embodiment, providing a permanent magnet synchronous generator parallel control method, the control method is as follows Figure 2 As shown, the following steps are included:

[0021] (1) Sampling the input current iu and iv on the AC side;

[0022] (2) Sampling the signal of the rotary transformer and calculating the electrical angle θr of the generator;

[0023] (3) iu, iv, θr are transformed into iα, iβ through abc / αβ coordinate transformation, and iα, iβ are transformed into id, iq1 through αβ / dq coordinate transformation;

[0024] (4) Receive the data iq2…iqn transmitted by the CAN bus;

[0025] (5) Calculate the difference between the average iq current of each module circuit and iq1, δ1 = iq1-(iq1+iq2+...iqn) / n. δ1 is passed through the PI regulator to obtain the coefficient disturbance rd1. The transfer function of the PI regulator is kp+ki / s, where kp is the proportional coefficient, ki is the integral coefficient, and s is the Laplace operator.

[0026] (6) The coefficient disturbance rd1 is added to the initial disturbance Rd1, and the result is multiplied by iq1 to obtain the given value Udc* of the DC voltage;

[0027] (7) The voltage Udc1 of the sampling capacitor 1 is subtracted from Udc* and passed through the voltage PI regulator to obtain the iq command value Iq*;

[0028] (8) Iq* is subtracted from iq and passed through the q-axis current PI regulator to obtain uq. Id* is a fixed value. Id* is subtracted from id and passed through the d-axis current PI regulator to obtain ud.

[0029] (9) ud and uq are transformed into uα and uβ through dq / αβ transformation, and uα and uβ are transformed into ua and ub through αβ / abc transformation. ua and ub are modulated by space vector SVPWM to obtain driving signals to drive IGBT module 1.

Claims

1. A permanent magnet synchronous generator parallel control device, characterized in that: The device comprises: n permanent magnet synchronous generators, n module circuits, a common capacitor, and a load, wherein n is a positive integer greater than 1. Each module circuit corresponds to a permanent magnet synchronous generator, which is used to convert the AC power generated by each permanent magnet synchronous generator into DC power. The DC side of each module circuit is connected to the CAN bus to transmit data. The DC output end of each module circuit is connected to a common capacitor, and the common capacitor is connected to a load.

2. A permanent magnet synchronous generator parallel control device according to claim 1, characterized in that: The module circuit includes: an IGBT module, a diode, a sampling capacitor, a sampling module, a driving module, a resolver decoding module, a main control chip, and a CAN communication module.

3. A permanent magnet synchronous generator parallel control device according to claim 2, characterized in that: The output of the IGBT module is connected in series with a diode after capacitor filtering, and the output of each IGBT module is connected to a common capacitor to supply power to various loads at the back end.

4. A permanent magnet synchronous generator parallel control device according to claim 2, characterized in that: The input end of the IGBT module is connected to the three-phase output end of the permanent magnet synchronous generator, the positive output end of the IGBT module is connected to the positive electrode of the diode and the positive electrode of the sampling capacitor, the negative electrode of the diode is connected to the positive electrode of the common capacitor, and the negative output end of the IGBT module is connected to the negative electrode of the sampling capacitor and the negative electrode of the common capacitor; the input end of the sampling module is connected to the three-phase output end of the permanent magnet synchronous generator and the sampling capacitor, the output end of the sampling module is connected to the main control chip, the input end of the drive module is connected to the main control chip, the output end of the drive module is connected to the IGBT module, the input end of the resolver decoding module is connected to the resolver of the permanent magnet synchronous generator, the output end of the resolver decoding module is connected to the main control chip, and the input end of the CAN communication module is connected to the main control chip.

5. A permanent magnet synchronous generator parallel control device according to claim 4, characterized in that: The sampling module includes a PI regulator for adjusting the proportional coefficient of the disturbance current, which can improve the control accuracy of the parallel current.

6. A permanent magnet synchronous generator parallel control device according to claim 1, characterized in that: The common capacitor is a thin film capacitor with a strong peak current capability, a capacitance greater than 2000uF, and a withstand voltage greater than 400V.

7. A permanent magnet synchronous generator parallel control device according to claim 2, characterized in that: The diode is a high-power diode, and a high-power diode is connected in series on the DC side of the generator to avoid circulating current in the generator.

8. A control method based on the permanent magnet synchronous generator parallel control device according to claim 5, characterized in that: The method comprises the following steps: (1) Sampling the input current iu and iv on the AC side; (2) Sampling the signal of the rotary transformer and calculating the electrical angle θr of the generator; (3) iu, iv, θr are transformed into iα, iβ through abc / αβ coordinate transformation, and iα, iβ are transformed into id, iq1 through αβ / dq coordinate transformation; (4) Receive the data iq2…iqn transmitted by the CAN bus; (5) Calculate the difference between the average iq current of each module circuit and iq1, δ1 = iq1-(iq1+iq2+...iqn) / n. δ1 is passed through the PI regulator to obtain the coefficient disturbance rd1. The transfer function of the PI regulator is kp+ki / s, where kp is the proportional coefficient, ki is the integral coefficient, and s is the Laplace operator. (6) The coefficient disturbance rd1 is added to the initial disturbance Rd1, and the result is multiplied by iq1 to obtain the given value Udc* of the DC voltage; (7) The voltage Udc1 of the sampling capacitor, Udc* is subtracted from Udc1 and passed through the voltage PI regulator to obtain the iq command value Iq*; (8) Iq* is subtracted from iq and passed through the q-axis current PI regulator to obtain uq. Id* is a fixed value. Id* is subtracted from id and passed through the d-axis current PI regulator to obtain ud. (9) ud and uq are transformed into uα and uβ through dq / αβ transformation, and uα and uβ are transformed into ua and ub through αβ / abc transformation. ua and ub are modulated by space vector SVPWM to obtain driving signals to drive the IGBT module.

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