Engine constant voltage controller and voltage control method

Abstract

This invention provides a constant voltage controller and voltage control method for an engine. The constant voltage controller includes a three-phase alternator and a voltage control system. The voltage control system includes a voltage sensor, a PLC, an excitation power supply, a power switch, a voltage acquisition switch, a start signal switch, an excitation output switch, and a 24V DC switching power supply. The input terminal of the voltage sensor is connected to the three-phase alternator, and the output terminal is connected to the PLC. The sensor is configured to acquire a voltage signal from one phase of the alternator and transmit it to the PLC. The output terminal of the PLC is connected to the excitation power supply and is configured to compare the voltage signal with a given voltage, and transmit the voltage comparison result to the excitation power supply via an RS485 port. The output terminal of the excitation power supply is connected to the excitation winding of the three-phase alternator and is configured to control the excitation current of the excitation winding based on the voltage comparison result. This constant voltage controller for an engine is stable in performance and low in cost.

Description

Technical Field

[0001] This invention relates to the field of aero-engine and generator technology, and more specifically, to an engine constant voltage controller for stabilizing the output voltage of a three-phase AC generator during ground testing on a certain type of engine test bench. This invention also relates to a voltage control method. Background Technology

[0002] Aero engines are equipped with three-phase AC generators. The output voltage of these generators is mainly related to engine speed, the number of coils in the excitation winding, and the excitation current. Engine speed is controlled by a constant-speed transmission mechanism, the number of coils in the excitation winding is fixed, and the excitation current is controlled by an existing hardware regulator. During ground testing of the engine, as a mandatory test item according to process requirements, a resistive load is applied to simulate aircraft loads during both slow and fast runs to verify the impact of the load on engine speed.

[0003] The existing hardware regulator TKB-2 includes discrete components such as resistors, capacitors, and operational amplifiers. All signal acquisition, control, and calculation are performed by hardware circuitry. Due to the special nature of aviation applications, high integration, small size, light weight, compact structure, and reliable and stable performance are the goals pursued. Therefore, the market price of TKB-2 is very high, with current alternatives costing as much as 565,000 yuan. Furthermore, in the aviation maintenance industry, the maintenance cycle of test bench equipment is a crucial factor that must be considered. The existing TKB-2 is a military component developed and put into use in the 1970s, employing 1970s technology and using discrete semiconductor devices. Due to technological advancements, it has been out of production for over a decade, and the electronic components used are difficult to find on the market. Even newly developed products require a maintenance cycle of 1-3 months; if a malfunction occurs, it will seriously affect the smooth progress of test runs.

[0004] Therefore, how to provide a low-cost, stable, easy-to-maintain constant voltage controller that can be directly replaced without modifying the original control circuit of the engine test bench is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides an engine constant voltage controller, which is based on sensor and PLC computer control technology and intelligently realizes the voltage control of a three-phase AC generator through software programming. Furthermore, the engine constant voltage controller can directly replace the existing hardware regulator TKB-2 during ground testing.

[0006] This invention provides a constant voltage controller for an engine, comprising: a three-phase alternator and a voltage control system; wherein, the voltage control system includes a voltage sensor, a PLC, an excitation power supply, a power switch, a voltage acquisition switch, a start signal switch, an excitation output switch, and a 24V DC switching power supply; the input terminal of the voltage sensor is connected to the three-phase alternator, and the output terminal of the voltage sensor is connected to the PLC. The voltage sensor is configured to acquire a voltage signal from one phase of the three-phase alternator and transmit the voltage signal to the PLC; the output terminal of the PLC is connected to the excitation power supply, and the PLC is configured to compare the voltage signal with a given voltage, and perform voltage comparison... The results are transmitted to the excitation power supply via the RS485 port; the output of the excitation power supply is connected to the excitation winding of the three-phase AC generator, and the excitation power supply is configured to control the excitation current of the excitation winding according to the voltage comparison results; the power switch is configured to turn the voltage control system on and off; the voltage acquisition switch is configured to turn the voltage sensor on and off; the start signal switch is configured to receive the start signal from the test workshop and turn the PLC on and off; the excitation output switch is configured to turn the excitation power supply on and off; the 24V DC switching power supply is configured to power the voltage sensor and the PLC; the 24V DC switching power supply and the excitation power supply are powered by the 220V standard voltage.

[0007] Optionally, the voltage control system also includes a frequency sensor, and the PLC is further configured with an expansion module for increasing the number of I / O points and / or changing the I / O ratio. The input terminal of the frequency sensor is connected to the three-phase AC generator, and the output terminal of the frequency sensor is connected to the PLC. The frequency sensor is configured to acquire a frequency signal from one phase of the three-phase AC generator and transmit the frequency signal to the PLC. The PLC is also configured to compare the frequency signal with a given frequency and transmit the frequency comparison result to the excitation power supply via an RS485 port. The excitation power supply is also configured to control the excitation current of the excitation winding according to the frequency comparison result. A 24V DC switching power supply is also configured to power the frequency sensor.

[0008] Optionally, the PLC and excitation power supply control the excitation current so that: when the resistive load of the three-phase AC generator is 0-100%, the single-phase voltage of the three-phase AC generator is stable at 115V±2.3V; when the resistive load of the three-phase AC generator is 100-150%, the single-phase voltage of the three-phase AC generator is stable at 115V±3.45V; and when the resistive load of the three-phase AC generator is 150-200%, the single-phase voltage of the three-phase AC generator is stable at 115V±5.17V.

[0009] Optionally, the PLC is further configured to control the excitation power supply to stop outputting excitation current when any of the following conditions are met: the voltage sensor detects a voltage signal higher than 125V; the voltage sensor detects a voltage signal lower than 100V; or the frequency sensor detects a frequency signal lower than 750Hz.

[0010] Optionally, the voltage sensor and frequency sensor acquire voltage and frequency signals respectively on the same phase of the three-phase AC generator; the voltage acquisition switch is configured to turn the voltage sensor and frequency sensor on and off.

[0011] Alternatively, the voltage control system and the existing hardware regulator can be installed in the same electrical cabinet.

[0012] Optionally, the start signal switch of the voltage control system shares the start signal from the test plant with the existing hardware regulator.

[0013] Optionally, the voltage sensor is WBV414M05 from Mianyang Weibao Electronics Co., Ltd., the frequency sensor is WBF124U01 from Mianyang Weibao Electronics Co., Ltd., the PLC is Siemens 6ES7288-1ST20-0AA0, and the DC power supply is Siemens 6ES7288-0DK10-0AA0.

[0014] This invention also provides a voltage control method using the aforementioned engine constant voltage controller, comprising the following steps: S1, turning on the power switch, voltage acquisition switch, start signal switch, and excitation output switch, and starting the 24V DC switching power supply; S2, the voltage sensor acquires a voltage signal from one phase of the three-phase AC generator and transmits the voltage signal to the PLC; the PLC compares the voltage signal with a given voltage and transmits the voltage comparison result to the excitation power supply via an RS485 port; the excitation power supply is connected to the excitation output of the three-phase AC generator. The excitation current of the excitation winding is controlled according to the voltage comparison result, so that: when the resistive load of the three-phase AC generator is 0-100%, the single-phase voltage of the three-phase AC generator is stable at 115V±2.3V; when the resistive load of the three-phase AC generator is 100-150%, the single-phase voltage of the three-phase AC generator is stable at 115V±3.45V; and when the resistive load of the three-phase AC generator is 150-200%, the single-phase voltage of the three-phase AC generator is stable at 115V±5.17V.

[0015] Optionally, the PLC is further configured to control the excitation power supply to stop outputting excitation current when any of the following conditions are met: the voltage sensor detects a voltage signal higher than 125V; the voltage sensor detects a voltage signal lower than 100V; or the frequency sensor detects a frequency signal lower than 750Hz.

[0016] Compared with the existing TKB-2 hardware regulator, the engine constant voltage controller and voltage control method provided by this invention have the following advantages:

[0017] (1) The engine constant voltage controller provided by the present invention adopts sensor and PLC computer control technology, and realizes automatic voltage regulation and over / under voltage, frequency protection and other functions of AC generator through software programming. It is stable, reliable and adjustable.

[0018] (2) The engine constant voltage controller provided by this invention can be installed in the same electrical cabinet as the existing TKB-2 hardware regulator and shares the start signal from the test bench with the existing TKB-2 hardware regulator. During the ground test of a certain type of engine, there are strict process requirements for the overall performance of the test bench. The engine constant voltage controller provided by this invention can directly replace the original control circuit of the engine test bench without modifying it, and can be used immediately after replacement. In addition, the test personnel can compare with the existing TKB-2 hardware regulator at any time and adjust the various parameter settings of the engine constant voltage controller provided by this invention to make its performance completely consistent with or better than that of the existing TKB-2 hardware regulator.

[0019] (3) The components of the engine constant voltage controller provided by the present invention can be easily obtained from the market, and the manufacturing and maintenance costs are low and convenient. This completely makes up for the shortcomings of the existing TKB-2 hardware regulator, which has high cost and difficult maintenance, and thus provides a strong guarantee for the completion of the test mission and the quality of engine maintenance. Attached Figure Description

[0020] To more clearly illustrate the technical solution of the present invention, the embodiments of the present invention will be further explained and described with reference to the following drawings. These drawings are only used to more conveniently and specifically describe the embodiments of the present invention and are not intended to limit the present invention.

[0021] Figure 1 This is an electrical schematic diagram of a conventional TKB-2 hardware regulator provided according to an exemplary embodiment of the present invention;

[0022] Figure 2 This is an electrical schematic diagram of an engine constant voltage controller provided according to an exemplary embodiment of the present invention;

[0023] Figure 3 This is a photograph of an engine constant voltage controller provided according to an exemplary embodiment of the present invention, housed within an electrical cabinet; and

[0024] Figure 4This is a schematic diagram of the software control principle of an engine constant voltage controller provided according to an exemplary embodiment of the present invention. Detailed Implementation

[0025] This invention provides a constant voltage controller for an engine, which intelligently controls the voltage of an alternator through software programming based on sensor and PLC computer control technology. This constant voltage controller is inexpensive to manufacture and maintain, and offers stable performance, allowing it to directly replace existing hardware regulators during ground testing.

[0026] The alternators installed in aircraft engines need to provide a stable intermediate-frequency voltage output to the aircraft's onboard equipment; therefore, a stable voltage control device is indispensable for the alternator. Due to the special nature of aviation applications, existing technologies use highly integrated, compact, and lightweight hardware regulators as voltage control devices. (Reference) Figure 1 , Figure 1 This is an electrical schematic diagram 100 of a conventional TKB-2 hardware regulator 102 provided according to an exemplary embodiment of the present invention. Figure 1 As shown, the dashed box on the left represents an AC generator 101, which consists of three-phase windings T1T2T3, a power supply winding Y, and an excitation winding L. The output terminals of all three-phase windings are connected to a resistive load and a hardware regulator 102. The power supply winding provides operating power to the hardware regulator 102. The hardware regulator 102 controls the excitation current in the excitation winding L, thereby controlling the three-phase output voltage of the AC generator. The power supply winding Y is connected to the hardware regulator 102 via wiring 2025, and the excitation winding L is connected to the hardware regulator 102 via wiring 2027. The hardware regulator 102 also includes wirings 2033 and 2035 for receiving start-up signals from the test chamber. When the hardware regulator 102 receives a start signal, wiring 2033 and 2035 are connected to start the hardware regulator 102. Simultaneously, the hardware regulator 102 monitors the voltage signal from the three-phase output terminals of the alternator and, through its internal discrete components such as capacitors, resistors, and operational amplifiers, controls the excitation current output to the excitation winding L based on the monitored voltage signal, thereby controlling the three-phase output voltage of the alternator. For simplicity, Figure 1 The discrete components in the hardware regulator 102 are not shown, but those skilled in the art should understand that the hardware regulator 102 can have corresponding functions through its hardware settings. The existing TKB-2 hardware regulator 102 is small in size and light in weight, making it suitable for use in aero-engine flight missions. However, during engine ground testing, the existing TKB-2 hardware regulator 102 has many drawbacks due to its manufacturing and maintenance costs.

[0027] In a preferred embodiment of the present invention, an engine constant voltage controller is provided, comprising: a three-phase alternator 101 and a voltage control system; wherein, the voltage control system includes a voltage sensor 201, a PLC 203, an excitation power supply 204, a power switch 301, a voltage acquisition switch 302, a start signal switch 303, an excitation output switch 304, and a 24V DC switching power supply 205; the input terminal of the voltage sensor 201 is connected to the three-phase alternator 101, and the output terminal of the voltage sensor 201 is connected to the PLC 203; the voltage sensor 201 is configured to acquire a voltage signal from one phase of the three-phase alternator 101 and transmit the voltage signal to the PLC 203; the PLC... The output terminal of PLC 203 is connected to the excitation power supply 204. PLC 203 is configured to compare the voltage signal with a given voltage and transmit the voltage comparison result to the excitation power supply 204 via RS485 port. The output terminal of the excitation power supply 204 is connected to the excitation winding of the three-phase AC generator 101. The excitation power supply 204 is configured to control the excitation current of the excitation winding according to the voltage comparison result. Power switch 301 is configured to turn the voltage control system on and off. Voltage acquisition switch 302 is configured to turn the voltage sensor 201 on and off. Start signal switch 303 is configured to receive the start signal from the test workshop and turn PLC 203 on and off. Excitation output switch 304 is configured to turn the excitation power supply 204 on and off. 24V DC switching power supply 205 is configured to power the voltage sensor 201 and PLC 203. 24V DC switching power supply 205 and excitation power supply 204 are powered by 220V standard voltage. Preferably, the voltage control system further includes a frequency sensor 202, and the PLC 203 is also equipped with an expansion module 305 for increasing the number of I / O points and / or changing the I / O ratio. The input terminal of the frequency sensor 202 is connected to the three-phase alternator 101, and the output terminal of the frequency sensor 202 is connected to the PLC 203. The frequency sensor 202 is configured to acquire a frequency signal from one phase of the three-phase alternator 101 and transmit the frequency signal to the PLC 203. The PLC 203 is also configured to compare the frequency signal with a given frequency and transmit the frequency comparison result to the excitation power supply 204 via an RS485 port. The excitation power supply 204 is also configured to control the excitation current of the excitation winding according to the frequency comparison result. The 24V DC switching power supply 205 is also configured to supply power to the frequency sensor 202. (Reference) Figure 2 , Figure 2 This is a schematic diagram 200 of the electrical principle of an engine constant voltage controller according to an exemplary embodiment of the present invention. Figure 2As shown, in the engine constant voltage controller provided by this invention, the original three-phase AC generator 101 is still used. Voltage sensor 201 and frequency sensor 202 measure the single-phase output voltage and frequency at any phase output terminal of the three-phase AC generator 101 and transmit the monitoring signals to PLC 203. PLC 203 compares the monitored voltage and frequency signals with preset values ​​and adjusts the excitation voltage and excitation current output by excitation power supply 204 to excitation winding L according to the comparison results. This invention does not use the power supply winding Y of the three-phase AC generator 101 to power the voltage control system. Instead, it uses an external 24V DC switching power supply 205 to power PLC 203, voltage sensor 201, and frequency sensor 202, making the power supply more stable and reliable. The excitation winding L of the three-phase AC generator 101 is connected to the excitation power supply 204 through the original wiring 2027, and the excitation current is provided by the excitation power supply 204. The existing test workshop start signal wiring 2033 and 2035 are connected to PLC 203 as the start signal switch 303 for PLC 203. Start signal switch 303 shares the start signal from the test workshop with the existing hardware regulator 102. When power switch 301, voltage acquisition switch 302, start signal switch 303, and excitation output switch 304 are turned on, voltage sensor 201 and frequency sensor 202 convert the monitored voltage and frequency signals into a standard 4-20mA current signal. This signal is output to PLC 203 for comparison with the given voltage and frequency. The compared signal is transmitted to the excitation power supply 204 via RS485 port, and then the excitation current is controlled. PLC 203 adjusts the excitation current to control the three-phase output voltage of the AC generator, stabilizing its single-phase voltage at approximately 115V. 115V AC voltage is a commonly used output voltage for aircraft generators, consistent with the voltage set by the existing TKB-2 hardware regulator 102. In a preferred embodiment of the present invention, the voltage sensor 201 and the frequency sensor 202 can be installed on the same phase of the three-phase alternator 101 to facilitate the simultaneous acquisition of voltage and frequency signals and feedback to the PLC 203. Without limitation, the voltage sensor 201 and the frequency sensor 202 can be installed on different phases of the three-phase alternator 101.

[0028] In a preferred embodiment of the invention, the voltage control system and the existing hardware regulator 102 are installed in the same electrical cabinet. (See reference) Figure 3 , Figure 3 This is a photograph 300 of an engine constant voltage controller (three-phase alternator 101 not shown) provided in an electrical cabinet according to an exemplary embodiment of the present invention. Figure 3As shown, the voltage control system provided by this invention can be installed in the same electrical cabinet as the existing TKB-2 hardware regulator 102. When using the existing TKB-2 hardware regulator 102, connect the existing TKB-2 hardware regulator 102 to the plug 306, and simultaneously disconnect the power switch 301, voltage acquisition switch 302, start signal switch 303, and excitation output switch 304. When using the engine constant voltage controller provided by this invention, disconnect the existing TKB-2 hardware regulator 102 from the plug 306, and simultaneously connect the power switch 301, voltage acquisition switch 302, start signal switch 303, and excitation output switch 304. During engine ground testing, those skilled in the art can switch the voltage regulator used at any time as needed. Installing the engine constant voltage controller provided by this invention in the same electrical cabinet as existing products saves the cost of replacing regulators, and at the same time facilitates the test personnel to test and improve the parameter settings in the PLC 203 voltage control system by comparing with the existing hardware regulator 102. It should be noted that if the voltage control system provided by this invention is used, the power switch 301 should be disconnected promptly after the work is completed to prevent the PLC 203 from being powered on for an extended period. Based on the actual conditions of ground testing on the test bench, this invention achieves seamless integration with the original constant-transmission generator control system of the original test control system without any modifications to the original test bench system and while maintaining the same technical requirements. It allows for direct replacement and immediate use, and is applicable to all test benches of a certain type of engine. This invention solves the problems of high hardware controller costs and difficult maintenance that have plagued the industry for years, not only saving costs but also permanently resolving the annoyance of long maintenance cycles affecting test missions.

[0029] In a preferred embodiment of the present invention, the PLC 203 and the excitation power supply 204 control the excitation current such that: when the resistive load of the three-phase AC generator 101 is 0-100%, the single-phase voltage of the three-phase AC generator 101 is stable at 115V±2.3V; when the resistive load of the three-phase AC generator 101 is 100-150%, the single-phase voltage of the three-phase AC generator 101 is stable at 115V±3.45V; and when the resistive load of the three-phase AC generator 101 is 150-200%, the single-phase voltage of the three-phase AC generator 101 is stable at 115V±5.17V. These parameters are based on tests of the existing TKB-2 hardware controller. The present invention, based on the PLC 203, sets the voltage regulation accuracy of the entire voltage control system to be consistent with the existing TKB-2 hardware controller, thus perfectly replacing the existing TKB-2 hardware controller. It should be understood that when different models of hardware controllers are used, those skilled in the art can test the hardware controller and thereby adjust the voltage regulation program stored in PLC 203 to meet actual needs.

[0030] In a preferred embodiment of the present invention, the PLC 203 is further configured to control the excitation power supply 204 to stop outputting excitation current when any of the following conditions are met: the voltage sensor 201 detects a voltage signal higher than 125V; the voltage sensor 201 detects a voltage signal lower than 100V; or the frequency sensor 202 detects a frequency signal lower than 750Hz. These three conditions correspond to the overvoltage protection, undervoltage protection, and underfrequency protection functions of the engine constant voltage controller provided by the present invention. Specifically, the overvoltage protection includes: when the output voltage is detected to be higher than 125V, disconnecting the excitation power supply 204 to stop the three-phase alternator 101 from generating electricity; the undervoltage protection includes: when the output voltage is detected to be lower than 100V, disconnecting the excitation power supply 204 to stop the three-phase alternator 101 from generating electricity; the underfrequency protection includes: when the output frequency is detected to be lower than 750Hz, disconnecting the excitation power supply 204 to stop the three-phase alternator 101 from generating electricity. Although the constant voltage controller for the engine provided by this invention has a voltage stabilization function, the three-phase AC generator 101 may still output unstable voltage or frequency under some unforeseen circumstances. Therefore, the PLC 203 also has a built-in protection function to promptly cut off the excitation power supply 204 when the generator output is unstable, thereby preventing accidents. (Reference) Figure 4 , Figure 4 This is a schematic diagram 400 illustrating the software control principle of an engine constant voltage controller according to an exemplary embodiment of the present invention. Figure 4As shown, the PLC 203 software control system simultaneously possesses feedback and protection functions. It stabilizes the current supplied by the excitation power supply 204 by monitoring voltage and frequency signals, and promptly cuts off the excitation power supply 204 in case of unexpected instability, protecting the resistive load and ensuring test run safety. In a preferred embodiment of the invention, the software program within the PLC 203 can be further configured to more closely simulate existing hardware controllers. Due to the fixed structure and limited precision of hardware controllers, their adjustments have a certain delay and hysteresis. For example, when performing undervoltage protection, the existing TKB-2 hardware controller can only disconnect the excitation current after detecting a voltage below 100V and delaying for 3.3 to 4.7 seconds. The engine constant voltage controller provided by this invention adopts a software control method based on PLC 203, which has extremely short inherent delay and hysteresis, thus exhibiting higher performance than the existing TKB-2 hardware controller. However, those skilled in the art should understand that when it is desired that the engine constant voltage controller provided by this invention has performance completely consistent with the TKB-2 hardware controller, the delay time can be specifically set according to the performance of the existing TKB-2 hardware controller. In some cases, the underfrequency protection and undervoltage protection functions can be configured with a certain delay condition to ensure that the output voltage or frequency of the three-phase AC generator 101 changes relatively stably. For example, in a preferred embodiment of the present invention, when implementing the underfrequency protection function, if the output frequency of the three-phase AC generator 101 is detected to be continuously decreasing and gradually falling below 750Hz, the excitation power supply 204 should be disconnected when the output frequency is above 725Hz; if the output frequency of the three-phase AC generator 101 is detected to be continuously increasing, the excitation power supply 204 should be connected when the output frequency is below 775Hz, and the difference in output frequency between connecting and disconnecting the excitation power supply 204 should not be less than 20Hz. Such a setting helps to protect the stable operation of the three-phase AC generator 101.

[0031] In one exemplary embodiment of the present invention, the voltage sensor 201 is a WBV414M05 from Mianyang Weibao Electronics Co., Ltd., the frequency sensor 202 is a WBF124U01 from Mianyang Weibao Electronics Co., Ltd., the PLC 203 is a Siemens 6ES7288-1ST20-0AA0, and the DC power supply is a Siemens 6ES7288-0DK10-0AA0. All of the above components are commercially available, and their manufacturing and maintenance costs are far lower than those of the existing TKB-2 hardware regulator 102.

[0032] This invention also provides a voltage control method using the aforementioned engine constant voltage controller, comprising the following steps: S1, turning on the power switch 301, voltage acquisition switch 302, start signal switch 303, and excitation output switch 304, and starting the 24V DC switching power supply 205; S2, the voltage sensor 201 acquires a voltage signal from one phase of the three-phase AC generator 101 and transmits the voltage signal to the PLC 203; the PLC... 203 compares the voltage signal with a given voltage and transmits the voltage comparison result to the excitation power supply 204 via RS485 port. The excitation power supply 204 is connected to the excitation winding of the three-phase AC generator 101 and controls the excitation current of the excitation winding according to the voltage comparison result, so that: when the resistive load of the three-phase AC generator 101 is 0-100%, the single-phase voltage of the three-phase AC generator 101 is stable at 115V±2.3V; when the resistive load of the three-phase AC generator 101 is 100-150%, the single-phase voltage of the three-phase AC generator 101 is stable at 115V±3.45V; and when the resistive load of the three-phase AC generator 101 is 150-200%, the single-phase voltage of the three-phase AC generator 101 is stable at 115V±5.17V. Optionally, PLC 203 is further configured to control the excitation power supply 204 to stop outputting excitation current when any of the following conditions are met: voltage sensor 201 detects a voltage signal higher than 125V; voltage sensor 201 detects a voltage signal lower than 100V; or frequency sensor 202 detects a frequency signal lower than 750Hz. The beneficial effects of this voltage control method are as described above regarding the engine constant voltage controller.

[0033] Numerous specific examples are provided in the embodiments described herein, and it should be understood that these examples are merely for illustrating the embodiments of the invention in detail and are not intended to limit the invention. Embodiments of the invention can be practiced without these specific examples. In some embodiments, structures and / or techniques well-known to those skilled in the art are not shown in detail so as not to obscure the understanding of the invention.

[0034] Although preferred embodiments of the invention have been shown and described herein, it will be readily understood by those skilled in the art that these embodiments are provided by way of example only. Various changes, modifications, and substitutions will occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein are optionally used to practice the invention. The scope of the invention is intended to be defined by the claims, and thereby covers structures within the scope of these claims and their equivalents.

Claims

1. An engine constant voltage controller characterized by, The utility model relates to a kind of voltage control system of three-phase alternator, including: Three-phase alternator (101) and voltage control system; Wherein, the voltage control system includes voltage sensor (201), PLC (203), excitation power supply (204), power switch (301), voltage acquisition switch (302), starting signal switch (303), excitation output switch (304) and 24 V DC switching power supply (205); The input end of the voltage sensor (201) is connected to the three-phase alternator (101), and the output end of the voltage sensor (201) is connected to the PLC (203). The voltage sensor (201) is configured to collect a voltage signal from one phase of the three-phase alternator (101) and transmit the voltage signal to the PLC (203). The output end of the PLC (203) is connected to the excitation power supply (204). The PLC (203) is configured to compare the voltage signal with a given voltage and transmit the voltage comparison result to the excitation power supply (204) through an RS485 port. The output end of the excitation power supply (204) is connected to the excitation winding of the three-phase alternator (101). The excitation power supply (204) is configured to control the excitation current of the excitation winding according to the voltage comparison result. The power switch (301) is configured to turn on and off the voltage control system. The voltage acquisition switch (302) is configured to turn on and off the voltage sensor (201). The starting signal switch (303) is configured to receive a starting signal from a test room and turn on and off the PLC (203). The excitation output switch (304) is configured to turn on and off the excitation power supply (204). The 24 V DC switching power supply (205) is configured to power the voltage sensor (201) and the PLC (203). The 24 V DC switching power supply (205) and the excitation power supply (204) are powered by a 220 V standard voltage. The voltage control system further includes a frequency sensor (202), and the PLC (203) is further configured with an I / O point number increasing and / or I / O ratio expansion module (305); The input end of the frequency sensor (202) is connected to the three-phase alternator (101), and the output end of the frequency sensor (202) is connected to the PLC (203). The frequency sensor (202) is configured to collect a frequency signal from one phase of the three-phase alternator (101) and transmit the frequency signal to the PLC (203). The PLC (203) is further configured to compare the frequency signal with a given frequency and transmit the frequency comparison result to the excitation power supply (204) through the RS485 port. The excitation power supply (204) is further configured to control the excitation current of the excitation winding according to the frequency comparison result. The 24 V DC switching power supply (205) is further configured to power the frequency sensor (202). The voltage control system and the existing hardware regulator (102) are installed in the same electrical cabinet; The start signal switch (303) of the voltage control system shares the start signal from the test room with the existing hardware regulator (102).

2. The engine constant transmission voltage controller according to claim 1, wherein the PLC (203) and the excitation power supply (204) control the excitation current so that: when the resistance load of the three-phase alternator (101) is 0-100%, the single-phase voltage of the three-phase alternator (101) is stabilized at 115 V±2.3 V; when the resistance load of the three-phase alternator (101) is 100-150%, the single-phase voltage of the three-phase alternator (101) is stabilized at 115 V±3.45 V; and when the resistance load of the three-phase alternator (101) is 150-200%, the single-phase voltage of the three-phase alternator (101) is stabilized at 115 V±5.17 V.

3. The engine constant transmission voltage controller according to claim 1, wherein the PLC (203) is further configured to control the excitation power supply (204) to stop outputting the excitation current when any of the following conditions is met: the voltage sensor (201) monitors that the voltage signal is higher than 125 V; the voltage sensor (201) monitors that the voltage signal is lower than 100 V; or the frequency sensor (202) monitors that the frequency signal is lower than 750 Hz.

4. The engine constant transmission voltage controller according to claim 1, wherein the voltage sensor (201) and the frequency sensor (202) collect the voltage signal and the frequency signal respectively in the same phase of the three-phase alternator (101); and the voltage collection switch (302) is configured to turn on and off the voltage sensor (201) and the frequency sensor (202).

5. The engine constant transmission voltage controller according to claim 1, wherein the voltage sensor (201) is WBV414M05 of Weibo Electronics Co., Ltd. in Mianyang, the frequency sensor (202) is WBF124U01 of Weibo Electronics Co., Ltd. in Mianyang, the PLC (203) is 6ES7288-1ST20-0AA0 of Siemens, and the 24 V DC switching power supply is 6ES7288-0DK10-0AA0 of Siemens. The method comprises the following steps: S1, turn on the power switch (301), the voltage collection switch (302), the start signal switch (303) and the excitation output switch (304), and start the 24 V DC switching power supply (205); S2, the voltage sensor (201) and the frequency sensor (202) collect the voltage signal and the frequency signal respectively in the same phase of the three-phase alternator (101); ​ 6. A voltage control method using the engine constant-voltage controller according to any one of claims 1 to 5, characterized by ​ ​ S2, the voltage sensor (201) collects a voltage signal at one phase of the three-phase alternator (101) and transmits the voltage signal to the PLC (203); the PLC (203) compares the voltage signal with a given voltage, and transmits the voltage comparison result to the excitation power supply (204) through the RS485 port; the excitation power supply (204) is connected to the excitation winding of the three-phase alternator (101), and controls the excitation current of the excitation winding according to the voltage comparison result, so that: when the resistance load of the three-phase alternator (101) is 0-100%, the single-phase voltage of the three-phase alternator (101) is stabilized at 115 V±2.3 V; when the resistance load of the three-phase alternator (101) is 100-150%, the single-phase voltage of the three-phase alternator (101) is stabilized at 115 V±3.45 V; and when the resistance load of the three-phase alternator (101) is 150-200%, the single-phase voltage of the three-phase alternator (101) is stabilized at 115 V±5.17 V.

7. The voltage control method according to claim 6, characterized in that, the PLC (203) is further configured to control the excitation power supply (204) to stop outputting the excitation current when any one of the following conditions is met: the voltage sensor (201) monitors that the voltage signal is higher than 125 V; the voltage sensor (201) monitors that the voltage signal is lower than 100 V; or the frequency sensor (202) monitors that the frequency signal is lower than 750 Hz.

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