Hybrid excitation synchronous generator excitation control system and joint simulation method

Abstract

The invention discloses a hybrid excitation synchronous generator excitation control system and a joint simulation method, and the system comprises an excitation power conversion unit and an excitation control unit, and the excitation power conversion unit integrates the functions of an APFC circuit and a half-bridge LLC resonant converter. Comprising a power supply input conversion unit, a boost input inductor L1, a first switch tube Q1, a second switch tube Q2, a capacitor C1, a resonant inductor L2, a resonant capacitor C2, an inductor L3, a transformer primary side excitation inductor Lm, a first diode VD1, a second diode VD2, a third diode VD3, a fourth diode VD4, a filter capacitor C3 and a load resistor R0. The excitation control unit comprises a modal distribution unit and a PWM signal generator. According to the invention, the terminal voltage of the harmonic brushless hybrid excitation synchronous generator and the third harmonic output current are used as feedback signals of the outer ring and the inner ring, the stability of the terminal voltage of the generator under different loads is improved by adjusting the induction current in the stator third harmonic winding, and the voltage quality of a power grid is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of generators, and in particular to an excitation control system and a joint simulation method for a hybrid excitation synchronous generator. Background Art

[0002] Generator excitation control refers to an important technology used to maintain the stable operation of synchronous generators and control the power factor in power systems. In power systems, the stability of the generator is crucial to maintaining the frequency and voltage of the system. By adjusting the excitation current of the generator, it is ensured that the generator can operate stably under different load conditions, and the output voltage and frequency meet the requirements of the power grid. The excitation control system controls the excitation current of the generator to ensure that the generator can operate stably under various load changes and external interference conditions. It has a direct impact on the operating reliability and economy of the generator.

[0003] The excitation control system generally consists of two main parts: the excitation power conversion unit and the excitation control unit. The excitation power conversion unit adjusts the current flowing through the third harmonic winding of the synchronous generator stator to provide excitation power for the synchronous generator, while the excitation control unit stabilizes the hybrid excitation synchronous generator in a relatively balanced state based on the input signal required by the control and the given reference.

[0004] There are many forms of existing excitation power conversion units, but the existing technology has problems such as narrow third harmonic excitation voltage regulation range, large size, low excitation power utilization, etc., which makes it difficult to meet the excitation requirements of hybrid excitation synchronous generators based on third harmonic excitation. The modeling of the hybrid excitation generator as the control object in the existing control strategy is relatively complicated, which has brought difficulties to the construction of simulation and the determination of controller parameters. Summary of the invention

[0005] The purpose of the present invention is to provide an excitation control system and a joint simulation method for a hybrid excitation synchronous generator, and propose a new circuit integrating active power factor correction (APFC) and half-bridge LLC resonant converter functions to adjust the excitation current. The inherent third harmonic energy in the hybrid excitation synchronous generator is used to solve the problem of insufficient excitation power of the traditional third harmonic excitation synchronous generator, and also improve the output power factor of the third harmonic winding. It is also proposed to use the mode allocation unit to reuse the switch to reduce the number of devices and improve the overall efficiency. In view of the problem that the mathematical model of the hybrid excitation synchronous generator is difficult to establish, a joint simulation based on Simulink, Simplore and Maxwell is proposed. It also effectively avoids the establishment of complex models, and the results are more convincing, which can reduce the number of iterations of the real prototype and is closer to reality.

[0006] In order to achieve the above object, the present invention provides the following technical solutions.

[0007] The present invention discloses a hybrid excitation synchronous generator excitation control system, which includes an excitation power conversion unit and an excitation control unit. The excitation power conversion unit adopts a topological structure and integrates the functions of APFC and half-bridge LLC resonant converter; the excitation power conversion unit includes a power input conversion unit, a boost input inductor L1, a first switch tube Q1, a second switch tube Q2, a capacitor C1, a resonant inductor L2, a resonant capacitor C2, an inductor L3, a transformer primary excitation inductor Lm, a first diode VD1, a second diode VD2, a third diode VD3, a filter capacitor C3, a load resistor R0, a first PWM signal generator, a second PWM signal generator and a mode distribution unit.

[0008] One end of the power input conversion unit is connected to the input end of the boost input inductor L1, the other end of the power input conversion unit is connected to one end of the capacitor C1, the output end of the boost input inductor L1 is respectively connected to the first end of the first switch tube Q1 and the input end of the half-bridge LLC resonant converter, the second end of the first switch tube Q1 is respectively connected to the first end of the second switch tube Q2 and one end of the capacitor C1, the first end of the second switch tube Q2 is connected to one end of the resonant cavity, and the second end of the second switch tube Q2 is connected to the capacitor C1 and the other end of the resonant cavity; the resonant cavity is composed of the resonant inductor L2, the inductor L3 and the resonant capacitor C2, the two ends of the resonant cavity are connected to the primary excitation inductance Lm of the transformer, the resonant inductance L2 and the resonant capacitor C2 are connected in series with the transformer, the inductor L3 is connected in parallel with the transformer, the upper end of the secondary inductance of the transformer is connected to the input end of the second diode VD2, and the lower end is connected to the input end of the third diode VD3, the output ends of the second diode VD2 and the third diode VD3 are connected to the input end of the filter capacitor C3, the lead line of the bisection point of the secondary inductance of the transformer is connected to the output end of the filter capacitor C3, and the capacitor C3 is connected in parallel with the load resistor R0; the two ends of the second switch tube Q2 are anti-parallel connected with the diode VD1.

[0009] The excitation control unit is mainly composed of a mode distribution unit and a PWM signal generator. According to the requirements of active power factor correction and half-bridge LLC resonant converter, the mode distribution unit combines the first PWM signal generator and the second PWM signal generator with a digital logic gate to send input signals of the first switch tube Q1 and the second switch tube Q2. The first PWM signal generator and the second PWM signal generator generate a first composite PWM signal S1 according to the mode distribution indication, and the first composite PWM signal S1 is input to the third end of the first switch tube Q1. The second PWM signal generator and the first PWM signal generator generate a second composite PWM signal S2 according to the mode distribution indication, and the second composite PWM signal S2 is input to the third end of the second switch tube Q2; the first composite PWM signal S1 and the second composite PWM signal S2 respectively control the conduction state of the first switch tube Q1 and the second switch tube Q2, so that the inductor current of the boost input inductor L1 follows the input voltage change of the power input conversion unit, realizes active power factor correction, and the half-bridge LLC resonant converter realizes a wide output adjustment range of the third harmonic winding current.

[0010] The generation process of the first composite PWM signal S1 and the second composite PWM signal S2 is as follows: given a capacitor C1 voltage reference value V ref The error is compared with the actual voltage feedback signal of capacitor C1, and the output of the outer loop voltage PI controller is used as the reference value of the current of the inner loop boost input inductor L1, connected to the first input terminal of the multiplier, and the second input terminal of the multiplier input signal u g / U gm , U gm Represents the output voltage U of the power conversion unit g The maximum value of the multiplier output and the current feedback value i of the boost input inductor L1 L1 The comparison error passes through one end of the inner loop current PI controller, the output end of the inner loop current PI controller is connected to the positive end of the first operational amplifier circuit, the negative end of the first operational amplifier circuit is input as a sawtooth carrier, and the output end of the first operational amplifier circuit outputs a first PWM signal P1; a given voltage reference value V of the filter capacitor C3 is given ref1The error is compared with the actual voltage feedback signal of the filter capacitor C3, and the error passes through the input end of the PI controller. The output end of the PI controller is connected to the positive end of the second operational amplifier circuit, the negative end of the second operational amplifier circuit is input with the sawtooth carrier, and the output end of the second operational amplifier circuit outputs the second PWM signal P2; the digital logic gate includes an OR gate circuit, a NAND gate circuit, and a NOT gate circuit; the first PWM signal P1 generated by the first operational amplifier circuit and the second PWM signal P2 generated by the second operational amplifier circuit are both input to the OR gate circuit, and the output signal of the OR gate circuit is the first composite PWM signal S1; at the same time, the second PWM signal P2 is input to the NOT gate circuit, and the output of the NOT gate circuit and the first PWM signal P1 are used together as the input of the NAND gate circuit, and the output of the NAND gate circuit is the second composite PWM signal S2. In the present technical solution, the third harmonic winding can be ideally equivalent to an AC power supply to provide the required voltage for the entire circuit. The active power factor correction APFC circuit and the half-bridge LLC resonant converter reuse the switch tube Q1, which reduces the number of switch tubes in structure and integrates the functions of the two topologies in function, so that the inductor current of the input inductor L1 follows the change of the third harmonic winding current to achieve active power factor correction, and use the half-bridge LLC resonant converter to achieve a wide output adjustment range of the third harmonic winding current.

[0011] The first switch tube Q1 and the second switch tube Q2 of the present invention are in three working modes.

[0012] When the first switch tube Q1 and the second switch tube Q2 are both turned on, the AC sine wave of the AC input power source AC is converted into a curved wave to charge the boost input inductor L1. The inductor current i L1 Rising, the first diode VD1 is turned off, the second diode VD2 is turned off, the third diode VD3 is turned off, and the resonant capacitor C2 and the filter capacitor C3 have no initial energy storage.

[0013] When the first switch tube Q1 is turned on and the second switch tube Q2 is turned off, the AC input power source AC is connected in series with the boost input inductor L1 to charge the capacitor C1. The energy stored in the boost input inductor L1 is released and stored in the capacitor C1. The inductor current i L1 First rises and then falls; capacitor C1 voltage V c1 Increase and release energy to the resonant cavity, the resonant inductor L2 is charged, the resonant capacitor C2 is charged, the energy of the resonant cavity is transferred to the secondary side through the primary excitation inductor Lm of the transformer, the second diode VD2 is turned on to provide energy to the resistor R0, the third diode VD3 is turned off, the filter capacitor C3 is filtered, and the first diode VD1 is turned off to protect the power supply part from reverse current.

[0014] When the first switch tube Q1 is turned off and the second switch tube Q2 is turned on, the resonant capacitor C2 and the resonant inductor L2 release energy and transfer energy to the secondary side through the primary excitation inductor Lm of the transformer, the second diode VD2 is turned off, and the third diode VD3 is turned on to provide energy to the resistor R0, the filter capacitor C3 filters, and the first diode VD1 is turned off to protect the power supply part from reverse current.

[0015] A more detailed description of the states of the first switch tube Q1 and the second switch tube Q2 in three working modes of the present invention is as follows: Given the average current value of the boost circuit, the first composite PWM signal S1 is adjusted to a high level, the second composite PWM signal S2 is also adjusted to a high level, the first switch tube Q1 and the second switch tube Q2 are both in the on mode, and the inductor current i of the boost input inductor L1 is L1 When the inductor current i L1 When the current is greater than the average current value, the second composite PWM signal S2 is adjusted to a high level, the first composite PWM signal S1 is kept at a low level, the first switch tube Q1 is in the on mode, the second switch tube Q2 is in the off mode, and the current i of the boost input inductor L1 is L1 When the inductor current i L1 When the current is less than the average current value, the second composite PWM signal S2 is adjusted to a high level, the first composite PWM signal S1 is kept at a high level, the first switch tube Q1 and the second switch tube Q2 are both in the on mode, and the inductor current i of the boost input inductor L1 is L1 rises, causing the inductor current i L1 Following the average current value change, active power factor correction is achieved.

[0016] The logical expression for adjusting the level of the first composite PWM signal S1 and the second composite PWM signal S2 is: S 1= P 1+ P 2; ; Wherein S1 represents the first composite PWM signal, S2 represents the second composite PWM signal, It indicates that the second PWM signal is negated.

[0017] When the first composite PWM signal S1 is adjusted to a low level and the second composite PWM signal S2 is adjusted to a high level, the first switch tube Q1 is in an off mode and the second switch tube Q2 is in an on mode, and the switching device frequency is set to the resonant frequency. At this time, the half-bridge LLC resonant converter operates at the resonant frequency, and a wide output adjustment range of the third harmonic winding current can be achieved.

[0018] The logical expression for adjusting the level of the first composite PWM signal S1 and the second composite PWM signal S2 is:S 1= P 1+ P 2; ; Wherein S1 represents the first composite PWM signal, S2 represents the second composite PWM signal, It indicates that the second PWM signal is negated.

[0019] It should be noted that the pulse signal generated by the first composite PWM signal generator and the second composite PWM signal generator and the logic composite of the mode allocation unit is used to control the excitation topology structure. The role of the mode allocation is to achieve the third harmonic output power factor correction, and on this premise, the third harmonic current wide range regulation is achieved. In order to achieve active power factor correction, the first switch tube Q1 and the second switch tube Q2 need to be triggered at the same time. As the inductor current exceeds the given average value, Q1 is turned on and Q2 is turned off. In this working mode, the inductor current will decrease, and then Q1 and Q2 will be turned on at the same time again. In this way, the inductor current follows the average current value repeatedly, that is, the active power factor correction is completed periodically. After ensuring the effect of active power factor correction, in order to achieve wide-range regulation of third harmonic current, within one cycle, the second part of the active power factor correction mode is divided into two parts of time to maintain the working state of the half-bridge LLC resonant converter, that is, the mode coverage time represented by the first switch tube Q1 being turned on and the second switch tube Q2 being turned off is divided into a part of time to maintain the two modes of the LLC resonant converter, one part of which keeps the switch tube Q1 turned on and the switch tube Q2 turned off, and the remaining part is allocated to the mode represented by the first switch tube Q1 being turned off and the second switch tube Q2 being turned on. The two divided parts of time together complete the wide-range regulation function of the third harmonic current.

[0020] That is, within one cycle, it first enters the mode represented by both switch tubes Q1 and Q2 being turned on, then enters the mode represented by switch tube Q1 being turned on and Q2 being turned off, and finally enters the mode represented by switch tube Q1 being turned off and Q2 being turned on. Subsequently, the cycle is repeated continuously to complete the third harmonic output power factor correction and the third harmonic transmission current wide range regulation function.

[0021] The invention discloses a joint simulation method for an excitation control system of a hybrid excitation synchronous generator. In the joint simulation method, a dual closed-loop control part is built in Simulink, a third harmonic brushless hybrid excitation synchronous generator model is built in Maxwell, and an excitation power conversion unit is built in Simplore. The three software models are integrated in Simplore by retrieving a retrieval path, wherein the outer ring armature voltage is connected to the line voltage between the BC phases, and the line voltage at the terminal of the hybrid excitation synchronous generator is kept unchanged by changing the external resistance load.

[0022] In the above technical scheme, the present invention provides technical effects and advantages.

[0023] (1) The present invention achieves the effect of multiplexing switches by integrating APFC and half-bridge LLC resonant converters with two common switch tubes, thereby reducing the number of switches and diodes. Two PWM signals are combined with digital logic gates to generate two switch signals, so that the inductance in the boost circuit follows the change of the input voltage to achieve active power factor correction. The third harmonic winding voltage is an alternating current with a frequency three times that of the armature voltage, which can be ideally equivalent to an AC voltage source. The introduction of the APFC integrated half-bridge LLC resonant converter not only improves the third harmonic output power factor, but also realizes a wide range of regulation of the third harmonic winding output current. This structure can maximize the utilization of the third harmonic energy, thereby solving the problem of low efficiency of the third harmonic in the process of compound excitation control of the hybrid excitation synchronous generator and insufficient excitation power of the hybrid excitation motor.

[0024] (2) The present invention is based on a third harmonic brushless hybrid excitation synchronous generator, and studies its excitation topology, i.e., control strategy, and joint simulation, and uses the results of the joint simulation of the hybrid excitation synchronous generator excitation closed-loop control to simulate the hybrid excitation synchronous generator's excitation control in reality. Joint simulation can further refine the electromagnetic properties of the motor and consider the actual working conditions of the motor, and also avoid complex modeling processes. It provides a solution for modeling hybrid excitation synchronous generators under different load conditions.

[0025] (3) The present invention uses the terminal voltage of the harmonic brushless hybrid excitation synchronous generator and the third harmonic output current as the feedback signals of the outer loop and the inner loop. By adjusting the induced current in the stator third harmonic winding, the stability of the generator terminal voltage under different loads is improved, thereby improving the grid voltage quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the excitation control principle of the third harmonic brushless hybrid excitation synchronous generator provided in Example 1 of the present invention.

[0027] Figure 2 This is the excitation control circuit diagram of the third harmonic brushless hybrid excitation synchronous generator provided in Example 1 of the present invention.

[0028] Figure 3 It is a working circuit diagram of the integrated APFC and half-bridge LLC resonant converter provided in Example 1 of the present invention in the first working mode.

[0029] Figure 4 It is a working circuit diagram of the integrated APFC and half-bridge LLC resonant converter provided in Example 1 of the present invention in the second working mode.

[0030] Figure 5 It is a working circuit diagram of the integrated APFC and half-bridge LLC resonant converter provided in Example 1 of the present invention in the third working mode.

[0031] Figure 6 This is a schematic diagram of the generation of the first composite PWM signal S1 and the second composite PWM signal S2 proposed in Embodiment 1 of the present invention.

[0032] Figure 7 It is a schematic diagram of the joint simulation method proposed in Example 2 of the present invention. DETAILED DESCRIPTION

[0033] The following specifically describes the embodiments of the present invention in conjunction with the accompanying drawings, which are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by technicians in the technical field of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0034] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0035] See also Figure 1 The excitation control principle of the third harmonic brushless hybrid excitation synchronous generator is shown as follows: the third harmonic winding on the stator side of the hybrid excitation synchronous generator induces the third harmonic in the hybrid excitation synchronous generator to generate an induced electromotive force, and the energy of the third harmonic winding on the stator side is transferred to the harmonic winding on the rotor side by generating an electromagnetic coupling phenomenon with the harmonic winding on the rotor side. The current generated on the harmonic winding is uncontrollably rectified, and the rectified direct current is transferred to the excitation winding on the rotor for excitation. The excitation current on the excitation winding is affected by adjusting the induced electromotive force of the third harmonic on the stator side, so as to achieve excitation control of the hybrid excitation synchronous generator. Example 1

[0036] The present embodiment describes a hybrid excitation synchronous generator excitation control system, the excitation control system includes an excitation power conversion unit and an excitation control unit. The excitation power conversion unit adopts a topological structure, integrating an active power factor correction circuit and a half-bridge LLC resonant converter; Figure 2 As shown, the excitation power conversion unit includes a power input conversion unit, a boost input inductor L1, a first switch tube Q1, a second switch tube Q2, a capacitor C1, a resonant inductor L2, a resonant capacitor C2, an inductor L3, a transformer primary excitation inductor Lm, a first diode VD1, a second diode VD2, a third diode VD3, a filter capacitor C3, and a load resistor R0.

[0037] One end of the power input conversion unit is connected to the input end of the boost input inductor L1, the other end of the power input conversion unit is connected to one end of the capacitor C1, the output end of the boost input inductor L1 is respectively connected to the first end of the first switch tube Q1 and the input end of the half-bridge LLC resonant converter, the second end of the first switch tube Q1 is respectively connected to the first end of the second switch tube Q2 and one end of the capacitor C1, the first end of the second switch tube Q2 is connected to one end of the resonant cavity, and the second end of the second switch tube Q2 is connected to the capacitor C1 and the other end of the resonant cavity; the resonant cavity is composed of the resonant inductor L2, the inductor L3 and the resonant capacitor C2, the two ends of the resonant cavity are connected to the primary excitation inductance Lm of the transformer, the resonant inductance L2 and the resonant capacitor C2 are connected in series with the transformer, the inductor L3 is connected in parallel with the transformer, the upper end of the secondary inductance of the transformer is connected to the input end of the second diode VD2, and the lower end is connected to the input end of the third diode VD3, the output ends of the second diode VD2 and the third diode VD3 are connected to the input end of the filter capacitor C3, the lead line of the bisection point of the secondary inductance of the transformer is connected to the output end of the filter capacitor C3, and the capacitor C3 is connected in parallel with the load resistor R0; the two ends of the second switch tube Q2 are anti-parallel connected with the diode VD1.

[0038] The excitation control unit is mainly composed of a mode distribution unit and a PWM signal generator. According to the requirements of active power factor correction and half-bridge LLC resonant converter, the mode allocation unit combines the first PWM signal generator and the second PWM signal generator with the digital logic gate to send input signals of the first switch tube Q1 and the second switch tube Q2. The first PWM signal generator and the second PWM signal generator generate a first composite PWM signal S1 according to the mode allocation indication, and the first composite PWM signal S1 is input to the third end of the first switch tube Q1. The second PWM signal generator and the first PWM signal generator generate a second composite PWM signal S2 according to the mode allocation indication, and the second composite PWM signal S2 is input to the third end of the second switch tube Q2. The first composite PWM signal S1 and the second composite PWM signal S2 control the conduction state of the first switch tube Q1 and the second switch tube Q2 respectively, so that the inductor current of the boost input inductor L1 follows the input voltage change of the power input conversion unit, and the active power factor correction is realized. Based on the half-bridge LLC resonant converter, the third harmonic output current is adjusted in a wide range, and the conditions when the motor is connected to different loads are adapted to enhance the flexibility of the excitation control system, and the overall efficiency is improved by combining the advantages of the two.

[0039] In this embodiment, the power input conversion unit includes: an AC input power supply AC and a rectifier bridge, the output end of the rectifier bridge is connected to the input end of the boost input inductor L1 and one end of the capacitor C1, and the rectifier bridge converts the sine wave of the AC input power supply AC into a sinusoidal wave.

[0040] In this embodiment, according to the conduction state of the first switch tube Q1 and the second switch tube Q2, the composite topology structure can be divided into three working modes, where: The first mode: see Figure 3 When the first switch tube Q1 and the second switch tube Q2 are both turned on, the AC sine wave of the AC input power source AC is converted into a sine wave to charge the boost input inductor L1. The inductor current i L1 Rising, the first diode VD1 is turned off, the second diode VD2 is turned off, the third diode VD3 is turned off, and the resonant capacitor C2 and the filter capacitor C3 have no initial energy storage.

[0041] Second mode: see Figure 4 When the first switch tube Q1 is turned on and the second switch tube Q2 is turned off, the AC input power source AC is connected in series with the boost input inductor L1 and then charges the capacitor C1. The energy stored in the boost input inductor L1 is released and stored in the capacitor C1. The inductor current i of the boost input inductor L1 is L1 First rises and then falls; capacitor C1 voltage V c1 Increase and release energy to the resonant cavity, the resonant inductor L2 is charged, the resonant capacitor C2 is charged, the energy of the resonant cavity is transferred to the secondary side through the primary excitation inductor Lm of the transformer, the second diode VD2 is turned on to provide energy to the resistor R0, the third diode VD3 is turned off, the filter capacitor C3 is filtered, and the first diode VD1 is turned off to protect the power supply part from reverse current.

[0042] The third mode: see Figure 5 When the first switch tube Q1 is turned off and the second switch tube Q2 is turned on, the resonant capacitor C2 and the resonant inductor L2 release energy and transfer energy to the secondary side through the primary excitation inductor Lm of the transformer. The second diode VD2 is turned off, and the third diode VD3 is turned on to provide energy to the resistor R0. The filter capacitor C3 filters, and the first diode VD1 is turned off to protect the power supply part from reverse current.

[0043] See also Figure 6 In this embodiment, the capacitor C1 voltage reference value V ref The error is compared with the actual voltage feedback signal of capacitor C1, and the output of the outer loop voltage PI controller is used as the reference value of the current of the inner loop boost input inductor L1, connected to the first input terminal of the multiplier, and the second input terminal of the multiplier input signal u g / U gm , U gm Represents the output voltage U of the power conversion unit g The maximum value of the multiplier output and the current feedback value i of the boost input inductor L1 L1The comparison error passes through one end of the inner loop current PI controller, the output end of the inner loop current PI controller is connected to the positive end of the first operational amplifier circuit, the negative end of the first operational amplifier circuit is input as a sawtooth carrier, and the output end of the first operational amplifier circuit outputs a first PWM signal P1; a given voltage reference value V of the filter capacitor C3 is given ref1 The error is compared with the actual voltage feedback signal of the filter capacitor C3, and the error passes through the input end of the PI controller. The output end of the PI controller is connected to the positive end of the second operational amplifier circuit, the negative end of the second operational amplifier circuit is input with the sawtooth carrier, and the output end of the second operational amplifier circuit outputs the second PWM signal P2; the digital logic gate includes an OR gate circuit, a NAND gate circuit, and a NOT gate circuit; the first PWM signal P1 generated by the first operational amplifier circuit and the second PWM signal P2 generated by the second operational amplifier circuit are both input to the OR gate circuit, and the output signal of the OR gate circuit is the first composite PWM signal S1; at the same time, the second PWM signal P2 is input to the NOT gate circuit, and the output of the NOT gate circuit and the first PWM signal P1 are used together as the input of the NAND gate circuit, and the output of the NAND gate circuit is the second composite PWM signal S2.

[0044] In this embodiment, given the average current value of the boost circuit, the first composite PWM signal S1 is adjusted to a high level, the second composite PWM signal S2 is also adjusted to a high level, the first switch tube Q1 and the second switch tube Q2 are both in the on mode, and the inductor current i of the boost input inductor L1 is L1 When the inductor current i L1 When the current is greater than the average current value, the second composite PWM signal S2 is adjusted to a high level, the first composite PWM signal S1 is kept at a low level, the first switch tube Q1 is in the on mode, the second switch tube Q2 is in the off mode, and the current i of the boost input inductor L1 is L1 When the inductor current i L1 When the current is less than the average current value, the second composite PWM signal S2 is adjusted to a high level, the first composite PWM signal S1 is kept at a high level, the first switch tube Q1 and the second switch tube Q2 are both in the on mode, and the inductor current i of the boost input inductor L1 is L1 rises, causing the inductor current i L1 Following the average current value change, active power factor correction is achieved.

[0045] The logical expression for adjusting the level of the first composite PWM signal S1 and the second composite PWM signal S2 is: S 1= P 1+ P 2; ; Wherein S1 represents the first composite PWM signal, S2 represents the second composite PWM signal, It indicates that the second PWM signal is negated.

[0046] When the first composite PWM signal S1 is adjusted to a low level and the second composite PWM signal S2 is adjusted to a high level, the first switch tube Q1 is in an off mode and the second switch tube Q2 is in an on mode, and the switching device frequency is set to the resonant frequency. At this time, the half-bridge LLC resonant converter operates at the resonant frequency, and a wide output adjustment range of the third harmonic winding current can be achieved.

[0047] The logical expression for adjusting the level of the first composite PWM signal S1 and the second composite PWM signal S2 is: S 1= P 1+ P 2; ; Wherein S1 represents the first composite PWM signal, S2 represents the second composite PWM signal, It indicates that the second PWM signal is negated.

[0048] It should be noted that the pulse signal generated by the first composite PWM signal generator and the second composite PWM signal generator and the logic composite of the mode allocation unit is used to control the excitation topology structure. The role of the mode allocation is to achieve the third harmonic output power factor correction, and on this premise, the third harmonic current wide range regulation is achieved. In order to achieve active power factor correction, the first switch tube Q1 and the second switch tube Q2 need to be triggered at the same time. As the inductor current exceeds the given average value, Q1 is turned on and Q2 is turned off. In this working mode, the inductor current will decrease, and then Q1 and Q2 will be turned on at the same time again. In this way, the inductor current follows the average current value repeatedly, that is, the active power factor correction is completed periodically. After ensuring the effect of active power factor correction, in order to achieve wide-range regulation of third harmonic current, within one cycle, the second part of the active power factor correction mode is divided into two parts of time to maintain the working state of the half-bridge LLC resonant converter, that is, the mode coverage time represented by the first switch tube Q1 being turned on and the second switch tube Q2 being turned off is divided into a part of time to maintain the two modes of the LLC resonant converter, one part of which keeps the switch tube Q1 turned on and the switch tube Q2 turned off, and the remaining part is allocated to the mode represented by the first switch tube Q1 being turned off and the second switch tube Q2 being turned on. The two divided parts of time together complete the wide-range regulation function of the third harmonic current.

[0049] That is, within one cycle, it first enters the mode represented by both switch tubes Q1 and Q2 being turned on, then enters the mode represented by switch tube Q1 being turned on and Q2 being turned off, and finally enters the mode represented by switch tube Q1 being turned off and Q2 being turned on. Subsequently, the cycle is repeated continuously to complete the third harmonic output power factor correction and the third harmonic transmission current wide range regulation function. Example 2

[0050] The combined simulation method of a hybrid excitation synchronous generator excitation control system described in this embodiment is as follows: Figure 7 As shown in the figure, based on the joint simulation of Simulink, Maxwell and Simplore, Simplore is a circuit topology design software, Maxwell is a simulation software for finite element analysis of motors, and Simulink is often used to build control simulation models. The modeling of hybrid excitation generators is relatively complex, and it is too cumbersome to solve the rotor electromagnetic equations, stator Maxwell equations, magnetic circuit equations, and winding differential equations. Joint simulation can skip the construction and solution of the model, and perform joint simulation through representative simulation software in different fields, making the simulation results more representative and reducing the number of iterations when testing real products.

[0051] In this embodiment, a dual closed-loop control part is built in Simulink, a third harmonic brushless hybrid excitation synchronous generator model is built in Maxwell, and an excitation power conversion unit is built in Simplore; by calling the retrieval path, the three software models are integrated in Simplore, in which the outer ring armature voltage is connected to the line voltage between the BC phases, and the line voltage at the terminal of the hybrid excitation synchronous generator is kept unchanged by changing the external resistance load.

[0052] In this embodiment, the requirements for setting up a joint simulation include: calling the S-Function module in Simulink and setting its name to "AnsoftSFunction" in order to establish a connection between the input and output in Simulink and the input and output in Simplore. Secondly, pins must be set in both to facilitate the access to the controlled object data, and Simplore must allow mutual access with Maxwell. When conducting a joint simulation, it is important to pay attention to whether the versions of the various software are compatible and whether they can be accessed from each other.

[0053] The integrated communication of the three joint simulation software is carried out in Simplore. The specific steps of the communication are as follows.

[0054] Build the control link in Simulink and determine its given value and feedback value. The control link includes three parts: controlling the outer loop voltage, inner loop current and PWM wave generation part. Set the input and output pins in Simulink, find the S-Function module in Simulink and change the name to "AnsoftSFunction". The uppercase and lowercase writing must be accurate. Then set the access path of Simplore in MATLAB. The purpose is to call the model in Simplore for integration. When selecting the path, you must pay attention to the version compatibility, otherwise an error will occur during simulation.

[0055] Import the motor finite element simulation model built in Maxwell into Simplore. Since Maxwell and Simplore are both modules in ANSYS software, you only need to allow Simplore to call Maxwell. Finally, ensure the consistency of simulation time in different software.

[0056] To design a third harmonic brushless hybrid excitation synchronous generator in Maxwell, it is necessary to determine the shape of the stator and rotor, the winding arrangement, and then perform magnetic field analysis and design, and finally perform performance analysis and optimization on the generator.

[0057] This embodiment proposes an excitation closed-loop control simulation method based on the combination of Simulink, Maxwell and Simplore. The control link is designed in Simulink, the excitation conversion unit is built in Simplore, and the hybrid excitation motor finite element model is built in Maxwell. The three models are integrated together in Simplore for joint simulation. Joint simulation can make the generator armature terminal voltage results more realistic under the dual closed-loop excitation control strategy, and can reduce the number of prototype iterations in real product testing.

[0058] The above are only preferred embodiments of the present invention and are 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 protection scope of the present invention.

[0059] Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Mentioning "further" in this article means that the specific features, structures or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present embodiment application. It can be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians of this field without making creative work are within the scope of protection of this application.

[0060] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A hybrid excitation synchronous generator excitation control system, characterized in that It includes an excitation power conversion unit and an excitation control unit; The excitation power conversion unit adopts a topological structure, integrating APFC and half-bridge LLC resonant converter functions; including a power input conversion unit, a boost input inductor L1, a first switch tube Q1, a second switch tube Q2, a capacitor C1, a resonant inductor L2, a resonant capacitor C2, an inductor L3, a transformer primary excitation inductor Lm, a first diode VD1, a second diode VD2, a third diode VD3, a filter capacitor C3, and a load resistor R0; One end of the power input conversion unit is connected to the input end of the boost input inductor L1, the other end of the power input conversion unit is connected to one end of the capacitor C1, the output end of the boost input inductor L1 is respectively connected to the first end of the first switch tube Q1 and the input end of the half-bridge LLC resonant converter, the second end of the first switch tube Q1 is respectively connected to the first end of the second switch tube Q2 and one end of the capacitor C1, the first end of the second switch tube Q2 is connected to one end of the resonant cavity, and the second end of the second switch tube Q2 is connected to the capacitor C1 and the other end of the resonant cavity; the resonant cavity is composed of the resonant inductor L2, the inductor L3 and the resonant capacitor C2, the two ends of the resonant cavity are connected to the primary excitation inductance Lm of the transformer, the resonant inductance L2 and the resonant capacitor C2 are connected in series with the transformer, the inductance L3 is connected in parallel with the transformer, the upper end of the secondary inductance of the transformer is connected to the input end of the second diode VD2, and the lower end is connected to the input end of the third diode VD3, the output ends of the second diode VD2 and the third diode VD3 are connected to the input end of the filter capacitor C3, the lead wire of the bisection point of the secondary inductance of the transformer is connected to the output end of the filter capacitor C3, and the capacitor C3 is connected in parallel with the load resistor R0; the two ends of the second switch tube Q2 are anti-parallel connected to the diode VD1; The excitation control unit includes a mode allocation unit and a PWM signal generator; the mode allocation unit combines the first PWM signal generator and the second PWM signal generator with a digital logic gate to send input signals of the first switch tube Q1 and the second switch tube Q2 according to the requirements of active power factor correction and half-bridge LLC resonant converter, the first PWM signal generator and the second PWM signal generator generate a first composite PWM signal S1 according to the mode allocation indication, the first composite PWM signal S1 is input to the third end of the first switch tube Q1, the second PWM signal generator and the first PWM signal generator generate a second composite PWM signal S2 according to the mode allocation indication, and the second composite PWM signal S2 is input to the third end of the second switch tube Q2; the first composite PWM signal S1 and the second composite PWM signal S2 respectively control the conduction state of the first switch tube Q1 and the second switch tube Q2, so that the inductor current of the boost input inductor L1 follows the input voltage change of the power input conversion unit, realizes active power factor correction, and realizes a wide output adjustment range of the third harmonic winding current based on the half-bridge LLC resonant converter; The generation process of the first composite PWM signal S1 and the second composite PWM signal S2 is as follows: given a capacitor C1 voltage reference value V ref The error is compared with the actual voltage feedback signal of capacitor C1, and the output of the outer loop voltage PI controller is used as the reference value of the current of the inner loop boost input inductor L1, connected to the first input terminal of the multiplier, and the second input terminal of the multiplier input signal u g / U gm , U gm Represents the output voltage U of the power conversion unit g The maximum value of the multiplier output and the current feedback value i of the boost input inductor L1 L1 The comparison error passes through one end of the inner loop current PI controller, the output end of the inner loop current PI controller is connected to the positive end of the first operational amplifier circuit, the negative end of the first operational amplifier circuit is input as a sawtooth carrier, and the output end of the first operational amplifier circuit outputs a first PWM signal P1; a given voltage reference value V of the filter capacitor C3 is given ref1 The error is compared with the actual voltage feedback signal of the filter capacitor C3, and the error passes through the input end of the PI controller. The output end of the PI controller is connected to the positive end of the second operational amplifier circuit, the negative end of the second operational amplifier circuit is input with the sawtooth carrier, and the output end of the second operational amplifier circuit outputs the second PWM signal P2; the digital logic gate includes an OR gate circuit, a NAND gate circuit, and a NOT gate circuit; the first PWM signal P1 generated by the first operational amplifier circuit and the second PWM signal P2 generated by the second operational amplifier circuit are both input to the OR gate circuit, and the output signal of the OR gate circuit is the first composite PWM signal S1; at the same time, the second PWM signal P2 is input to the NOT gate circuit, and the output of the NOT gate circuit and the first PWM signal P1 are used together as the input of the NAND gate circuit, and the output of the NAND gate circuit is the second composite PWM signal S2; The states of the first switch tube Q1 and the second switch tube Q2 in three working modes: When the first switch tube Q1 and the second switch tube Q2 are both turned on, the AC sine wave of the AC input power source AC is converted into a curved wave to charge the boost input inductor L1. The inductor current i L1 Rising, the first diode VD1 is turned off, the second diode VD2 is turned off, the third diode VD3 is turned off, and the resonant capacitor C2 and the filter capacitor C3 have no initial energy storage; When the first switch tube Q1 is turned on and the second switch tube Q2 is turned off, the AC input power source AC is connected in series with the boost input inductor L1 to charge the capacitor C1. The energy stored in the boost input inductor L1 is released and stored in the capacitor C1. The inductor current i L1 First rises and then falls; capacitor C1 voltage V c1 Increase and release energy to the resonant cavity, resonant inductor L2 is charged, resonant capacitor C2 is charged, the energy of the resonant cavity is transferred to the secondary side through the primary side excitation inductor Lm of the transformer, the second diode VD2 is turned on to provide energy to the resistor R0, the third diode VD3 is turned off, the filter capacitor C3 is filtered, and the first diode VD1 is turned off to protect the power supply part from reverse current; When the first switch tube Q1 is turned off and the second switch tube Q2 is turned on, the resonant capacitor C2 and the resonant inductor L2 release energy and transfer energy to the secondary side through the primary excitation inductor Lm of the transformer, the second diode VD2 is turned off, and the third diode VD3 is turned on to provide energy to the resistor R0, the filter capacitor C3 filters, and the first diode VD1 is turned off to protect the power supply part from reverse current.

2. A joint simulation method for a hybrid excitation synchronous generator excitation control system as claimed in claim 1, characterized in that Build a dual closed-loop control part in Simulink, build a third harmonic brushless hybrid excitation synchronous generator model in Maxwell, and build an excitation power conversion unit in Simplore; by retrieving the retrieval path, the three software models are integrated in Simplore, in which the outer ring armature voltage is connected to the line voltage between the BC phases, and the line voltage at the terminal of the hybrid excitation synchronous generator is kept unchanged by changing the external resistance load.

Images