A three-stage generator power controller and its control method based on adaptive power allocation

Abstract

This invention discloses a three-stage generator power controller and its control method based on adaptive power allocation. The power controller uses a power ratio command value issued by a BPCU to adaptively allocate power to two or more generators. One generator is used as a reference motor, and the output power of the other generators is matched with that of the reference motor. The generator output state is determined based on the output current and voltage values, so that the output power ratio between the reference motor and the control motor gradually approaches the theoretical value. This invention solves the problems of difficult parallel grid-connected control of three-stage generators and inaccurate power allocation under high power conditions, and has strong practicality.

Description

Technical Field

[0001] This invention belongs to the field of aviation electrical systems, specifically relating to a three-stage generator power controller and its control method based on adaptive power allocation. Background Technology

[0002] With the rapid development of more-electric aircraft, electrical energy is gradually replacing other forms of secondary energy to achieve uniformity in aircraft secondary energy systems. Compared to the previously widely used 400Hz AC power supply system, the 270V high-voltage DC power supply system offers significant advantages such as larger capacity, higher efficiency, higher reliability, lighter weight, and better electromagnetic compatibility. It is currently used as the main power source in many advanced military aircraft such as the F-22, F-35, and RAH-66. A single three-stage generator is clearly insufficient to meet the ever-increasing power demands of aircraft, necessitating research into parallel grid-connected control strategies for three-stage generators.

[0003] The three-stage generators on aircraft have a large power output, and the line impedance has a significant impact on the aircraft's power supply system, causing a substantial voltage drop.

[0004] When employing traditional droop control strategies, the generator output impedance cannot be guaranteed to be completely consistent, leading to inaccurate power distribution and uneven current distribution. In other words, power cannot be strictly distributed according to the set reference value, resulting in a certain degree of error. Furthermore, the virtual impedance inherent in traditional droop control causes changes in the voltage reference value, thus causing voltage drop. Summary of the Invention

[0005] To address the shortcomings in the aforementioned background technology, this invention provides a three-stage generator power controller and its control method based on adaptive power allocation.

[0006] The three-level generator power controller based on adaptive power allocation includes: busbar power controller (BPCU) and generator controller (GCU).

[0007] The GCU consists of an auxiliary power supply circuit, an analog signal conditioning circuit, a DSP control circuit, and a drive circuit. It is powered by the permanent magnet generator of the three-stage generator. The analog signal conditioning circuit collects information such as DC voltage and current output from the three-stage generator through the three-phase controlled rectifier bridge. The internal DSP control circuit calculates the data and outputs a PWM signal, which is amplified by the drive circuit and directly controls the excitation current of the exciter in the three-stage generator, thereby controlling the generator's output power.

[0008] The busbar power controller consists of an analog signal conditioning circuit and a DSP control circuit. It receives instructions from the host computer, controls the GCU, and then controls the power distribution of the generator set.

[0009] The control method for a three-stage generator power controller based on adaptive power allocation includes droop control based on voltage compensation control and dynamic droop coefficient control based on current.

[0010] In traditional droop control, when the generator output impedance is approximately a purely resistive load, the following current relationship can be obtained when two generators are connected in parallel:

[0011] (1)

[0012] in, This is the rectified output current of the left generator. This is the rectified output current of the right generator. The impedance of the left generator output line is... The impedance of the right generator output line is given.

[0013] According to formula (1), we know that the voltage provided by the two generators to the load is the same, and the current ratio is determined by the line impedance from the generator output terminal to the load terminal. Therefore, controlling the line impedance ratio can control the current ratio, and thus control the output power of the two generators.

[0014] Under high power conditions, the actual impedance of the line can cause a voltage drop, resulting in a terminal voltage of less than 270V supplied to the load. This can cause difficulties in parallel connection and grid connection. A voltage compensation control method is used to solve this problem.

[0015] (2)

[0016] in, This is the output dynamic voltage reference value. Given a reference value for the output voltage, This refers to the DC current output by the rectified generator. The droop coefficient is... , , For PID parameters, is the load voltage, and s is the differential controller.

[0017] Furthermore, the power distribution is determined by the line impedance ratio, which includes two parts: virtual impedance (droop factor) and actual line impedance. Since the control is based on the virtual impedance ratio for power distribution, the existence of the actual impedance will make the current distribution inaccurate. Therefore, dynamic droop factor control based on current is adopted.

[0018] (3)

[0019] in, This is the weighted average current.

[0020] The control method used in the reference generator is as follows:

[0021] (4)

[0022] The control method used to control the generator:

[0023] (5)

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. Power distribution is achieved by embedding droop control into excitation current control. Controlled rectification can be used at the generator output, without the need for additional controllable DC-DC or controllable AC-DC circuits.

[0026] Second, it can achieve parallel grid connection control of three-stage generators at relatively high power, and adopts voltage compensation control to ensure stable and unbiased output voltage.

[0027] Third, the current distribution is precise. It adopts dynamic droop coefficient control based on current, which makes it difficult to determine the ratio of the output line impedance of a three-stage generator. The power distribution is strictly distributed according to the ratio.

[0028] IV. Each generator controller (GCU) can determine the operating condition. At the same time, the above controllers can control the generator using different methods under four different operating conditions. The four different operating conditions are: power sharing condition, power uneven distribution condition, load change condition, and power ratio change condition. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0030] Figure 2 For reference, see the generator control block diagram;

[0031] Figure 3 Control block diagram for generator control;

[0032] Figure 4 shows the simulation results of power sharing under operating condition 1;

[0033] Figure 5 shows the simulation results of uneven power distribution under two operating conditions;

[0034] Figure 6 shows the simulation results of three load mutations under the operating conditions;

[0035] Figure 7 shows the simulation results of power ratio mutation under four operating conditions; Detailed Implementation

[0036] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0037] The control method for a three-stage generator power controller based on adaptive power allocation includes droop control based on voltage compensation control and dynamic droop coefficient control based on current.

[0038] In traditional droop control, when the generator output impedance is approximately a purely resistive load, the following current relationship can be obtained when two generators are connected in parallel:

[0039]

[0040] in, This is the rectified output current of the left generator. This is the rectified output current of the right generator. The impedance of the left generator output line is... The impedance of the right generator output line is given.

[0041] According to formula (1), we know that the voltage provided by the two generators to the load is the same, and the current ratio is determined by the line impedance from the generator output terminal to the load terminal. Therefore, controlling the line impedance ratio can control the current ratio, and thus control the output power of the two generators.

[0042] Under high power conditions, the actual impedance of the line can cause a voltage drop, resulting in a terminal voltage of less than 270V supplied to the load. This can cause difficulties in parallel connection and grid connection. A voltage compensation control method is used to solve this problem.

[0043]

[0044] in, This is the output dynamic voltage reference value. Given a reference value for the output voltage, This refers to the DC current output by the rectified generator. The droop coefficient is... , , For PID parameters, is the load voltage, and s is the differential controller.

[0045] Furthermore, the power distribution is determined by the line impedance ratio, which includes two parts: virtual impedance (droop factor) and actual line impedance. Since the control is based on the virtual impedance ratio for power distribution, the existence of the actual impedance will make the current distribution inaccurate. Therefore, dynamic droop factor control based on current is adopted.

[0046]

[0047] in, This is the weighted average current.

[0048] The control method used in the reference generator is as follows:

[0049]

[0050] The control method used to control the generator:

[0051]

[0052] The specific architecture for implementing the above methods is as follows: Figure 1 As shown.

[0053] like Figure 1 As shown, the busbar power controller consists of an analog signal conditioning circuit and a DSP control circuit. It receives commands from the host computer and controls GCU1 and GCU2. Each GCU judges the commands from the host computer and the generator's operating condition, thereby controlling the power distribution between the left and right generators. The GCU consists of an auxiliary power supply circuit, an analog signal conditioning circuit, a DSP control circuit, and a drive circuit. It is powered by the permanent magnet generator of the three-stage generator. The analog signal conditioning circuit collects information such as DC voltage and current output from the three-phase controlled rectifier bridge of the three-stage generator. The internal DSP control circuit calculates this information and outputs a PWM signal, which is amplified by the drive circuit and directly controls the excitation current of the exciter in the three-stage generator, thus controlling the power. GCU1 controls the left generator, making it the reference generator. Only voltage compensation control is used, so only data acquisition is required. Information, control diagrams such as Figure 2 As shown. GCU2 controls the right generator, making it the control generator. Voltage compensation control and current-based dynamic droop coefficient control are employed, therefore data acquisition is required. Information, control diagrams such as Figure 3 As shown.

[0054] Operating Condition 1: Power Sharing. The control method is as follows: the BPCU issues commands to the two GCUs, which then perform power sharing at a 1:1 ratio. The total power is 50kW. Each generator should output 270V, with an output current of approximately 92.59A and a power of 25kW. The left generator's line impedance is 0.001Ω, and the right generator's line impedance is 0.002Ω. Simulation results are as follows... Figure 4 As shown, the output voltage and output power are basically within the range of the reference values, the power is strictly distributed in a 1:1 ratio, and there is no voltage drop.

[0055] Operating Condition 2: Uneven Power Distribution. The control method is as follows: The BPCU issues commands to the two GCUs, which then distribute power in a 3:2 ratio. Each generator's output voltage should be 270V, with a total power of 50kW. The left generator output power is 30kW, and the right generator output power is 20kW. The left generator's line impedance is 0.001Ω, and the right generator's line impedance is 0.002Ω. Simulation results are as follows... Figure 5 As shown, the output voltage and output power are basically within the range of the reference values, the power is strictly distributed in a 3:2 ratio, and there is no voltage drop.

[0056] Operating Condition 3: Load Sudden Change. The control method is as follows: The BPCU issues commands to the two GCUs, which then perform power distribution at a 1:1 ratio. Each generator's output voltage should be 270V. The total power before the load sudden change is 50kW, and the total power after the load sudden change is 100kW. The impedance at the left generator's line terminal is 0.001Ω, and the impedance at the right generator's line terminal is 0.002Ω. Simulation results are as follows: Figure 6 As shown, the output voltage and output power before and after the mutation are basically without error from the reference value, the power is strictly distributed in a 1:1 ratio, and there is no voltage drop.

[0057] Operating Condition 4: Sudden Power Ratio Change. The control method is as follows: The BPCU issues commands to the two GCUs, which then perform power allocation, changing the power allocation ratio from 1:1 to 3:2. Each generator's output voltage should be 270V, and the total power should be 50kW. Before the change, the left and right generators each output 25kW; after the change, the left generator outputs 30kW, and the right generator outputs 20kW. Simulation results are as follows... Figure 7 As shown, the output voltage and output power before and after the mutation are basically without error from the reference value, the power is strictly distributed according to 1:1 or 3:2, and there is no voltage drop.

[0058] The waveform results demonstrate that the proposed three-stage generator power controller and its control method based on adaptive power allocation can achieve parallel grid-connected control of three-stage generators under high power conditions. Furthermore, the three-stage generator can output power according to the allocated power ratio, unaffected by the actual terminal impedance of the generator. The output voltage remains stable at 270V, unaffected by the droop control voltage drop, meeting the requirements of aircraft high-voltage DC systems. In summary, although the basic structure, principle, and method of this invention have been specifically illustrated through the above examples, it should not be considered that the specific implementation of this invention is limited to these descriptions. For those skilled in the art, certain deductions or substitutions can be made without departing from the concept of this invention.

Claims

1. A three-stage generator power controller based on adaptive power allocation, characterized in that: Each generator power controller (GCU) collects and calculates the DC voltage and current output by the three-stage generator through the control rectifier bridge, and then directly controls the excitation current of the exciter in the three-stage generator. Each generator power controller (GCU) can determine the operating conditions, and the aforementioned power controllers can control the generator using different methods under four different operating conditions. The four different operating conditions are: power sharing condition, power uneven distribution condition, load change condition, and power ratio change condition. The power adaptive distribution control method is embedded into the excitation current control of a three-stage generator, eliminating the need for additional controllable DC-DC or controllable AC-DC converters. The power adaptive allocation control method of the power controller includes: droop control based on voltage compensation control and current-based dynamic droop coefficient control. Under high power conditions, the actual impedance of the line can cause a voltage drop, resulting in the terminal voltage supplied to the load being less than 270V. This needs to be addressed using voltage compensation control methods. in, This is the output dynamic voltage reference value. Given a reference value for the output voltage, This refers to the DC current output by the rectified generator. The droop coefficient is... , , For PID parameters, is the load voltage, and s is the differential controller; Power distribution is determined by the line impedance ratio, which includes two parts: virtual impedance (i.e., droop factor) and actual line impedance. Because the control is based solely on the virtual impedance ratio, the presence of the actual impedance will cause inaccurate current distribution. Therefore, dynamic droop factor control based on current is adopted. in, It is the weighted average current of the rectified output current of the left generator and the rectified output current of the right generator.

2. A three-stage generator power controller based on adaptive power allocation as described in claim 1, characterized in that: When the output impedance of the generator is a purely resistive load, the following current relationship can be obtained when two generators are connected in parallel: in, This is the rectified output current of the left generator. This is the rectified output current of the right generator. The impedance of the left generator output line is... The impedance of the right generator output line is given.

3. A control method implemented by a three-stage generator power controller based on adaptive power allocation as described in claim 1, characterized in that: The power adaptive distribution control method is used to achieve functions such as voltage stabilization, current stabilization, and precise power distribution after multiple generators are connected in parallel. Based on traditional droop control, the specific control method is to select one generator as the reference generator and the other generators as control generators. The control generators control the output power to gradually approach the reference generator based on the command value issued by the busbar power controller. The reference generator only introduces voltage compensation control, while the control generator, in addition to introducing voltage compensation control, adds dynamic droop coefficient control based on current to solve the problem of inaccurate current distribution caused by impedance mismatch after multiple generators are connected in parallel. The control method used in the reference generator is as follows: The control method used to control the generator: in, This is the output dynamic voltage reference value. Given a reference value for the output voltage, This refers to the DC current output by the rectified generator. The droop coefficient is... , , For PID parameters, This is the load voltage. is the weighted average current of the rectified output current of the left generator and the rectified output current of the right generator, and s is the differential controller.

4. The control method implemented by the three-stage generator power controller based on adaptive power allocation as described in claim 3, characterized in that: A mathematical model for adaptive power distribution control was established, and a parallel model of two three-stage generators was built for verification.

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