Aero-engine rotating speed signal generator and control method

Abstract

The invention relates to the field of aero-engine testing, in particular to an aero-engine rotating speed signal generator and a control method, and the system comprises the steps that a main control module receives a test demand input by a user, selects and determines the model, matching frequency, voltage and phase parameters of a tachometer sensor needing to be simulated based on the test demand, and transmits the parameters to a DSP processor; the DSP processor receives parameters issued by the main control module and generates an SPWM signal through a timer; the timer is configured to be in a circulation mode, and the period of the PWM signal is changed by changing the initial value of the timer; the inversion module converts the isolated SPWM waveform into a three-phase alternating current signal and outputs the three-phase alternating current signal; and the detection module measures data of the three-phase alternating current signal output by the inversion module in real time and feeds back the data to the main control module to form closed-loop control. Test errors caused by performance errors of the sensor are avoided, and the actual performance of the tachometer indicator can be evaluated more accurately.

Description

Technical Field

[0001] The present application relates to the technical field of aircraft engine testing, and in particular to an aircraft engine speed signal generator and a control method. Background Art

[0002] An aircraft engine tachometer indicator is a key onboard instrument that displays the aircraft's engine speed in real time. It primarily consists of a hairspring, a pointer deflection indicator mechanism, a scale panel, and a synchronous motor. Given its unique characteristics, tachometer indicators must be regularly disassembled and inspected to ensure accuracy and reliability.

[0003] However, the existing tachometer indicator testing process presents numerous challenges. For one thing, when performing a separate tachometer indicator inspection, a new tachometer sensor of appropriate specifications must be used as the speed input standard. However, new tachometer sensors have inherent performance errors, which can introduce the sensor's own performance errors into the indicator test. This results in inaccurate test results and can easily lead to incorrect interpretations of tachometer indicator performance, compromising the assessment of the tachometer indicator's actual performance.

[0004] On the other hand, when checking multiple tachometer indicators, the process becomes cumbersome because each tachometer indicator requires a corresponding tachometer sensor. Frequent replacement of sensors of varying specifications not only increases operational complexity and time, but also increases inventory pressure on various spare parts, raising inspection costs and management difficulties. Summary of the Invention

[0005] In response to the above-mentioned problems existing when using a tachometer sensor to test a tachometer indicator, the present application provides an aircraft engine speed signal generator and a control method.

[0006] In a first aspect, the technical solution of the present invention provides an aircraft engine speed signal generator, comprising a main control module, the main control module being connected to a DSP processor, the DSP processor being connected to an inverter module via a signal isolation module, and the inverter module being connected to a detection module; The main control module receives the test requirements input by the user, selects and determines the tachometer sensor model to be simulated based on the test requirements, and has a built-in tachometer sensor model database. The main control module automatically matches the frequency, voltage, and phase parameters in the tachometer sensor model database according to the tachometer sensor model and sends them to the DSP processor; The DSP processor receives the parameters sent by the main control module and generates an SPWM signal through a timer. The timer is configured in a cyclic mode. By changing the initial value of the timer, the period of the PWM signal is changed, that is, the output frequency of the PWM waveform is changed. The signal isolation module electrically isolates the SPWM waveform output by the DSP processor; The inverter module converts the isolated SPWM waveform into a three-phase AC signal and outputs it; The detection module measures the data of the three-phase AC signal output by the inverter module in real time and feeds the data back to the main control module to form a closed-loop control.

[0007] Working in conjunction with a DSP processor via a main control module, this signal generator automatically matches and simulates signals from different tachometer sensor models based on user-entered test requirements, significantly improving test efficiency and accuracy. A built-in database of tachometer sensor models enables the system to quickly acquire corresponding frequency, voltage, and phase parameters, laying the foundation for subsequent accurate analog signal generation. The signal isolation module effectively prevents electrical interference, ensuring system stability and reliability. The closed-loop control implemented by the detection module monitors output signal data in real time and provides feedback to the main control module for timely parameter adjustment to ensure the accuracy and stability of the analog signal.

[0008] As a preferred embodiment of the technical solution of the present invention, the main control module receives the tachometer sensor model and target speed through the user interface, matches the number of motor pole pairs according to the tachometer sensor model database, converts the target speed into the target frequency, obtains the target voltage and V / F ratio according to the preset V / F curve table, sets the target phase offset of the three-phase SPWM waveform, and transmits the target frequency, V / F ratio, and target phase offset to the DSP processor.

[0009] The main control module accurately converts the target speed into the target frequency and determines the target voltage and V / F ratio based on a preset V / F curve table, enabling precise control of the output signal. Setting the target phase angle of the three-phase SPWM waveform ensures the phase accuracy of the output signal, meeting the phase requirements of different tachometer sensors.

[0010] As a preferred embodiment of the technical solution of the present invention, the DSP processor reads discrete values ​​from a pre-stored sine function discrete value table, calculates the instantaneous amplitude of the modulation wave in combination with the V / F ratio, generates a triangular carrier through a timer, compares the modulation wave and the carrier in real time, and outputs a high level when the instantaneous amplitude of the modulation wave is greater than the carrier amplitude, otherwise it outputs a low level to generate an SPWM pulse sequence; and calculates the dead time according to the target frequency, and loads the calculated dead time value in real time through the DB module.

[0011] The DSP processor calculates the instantaneous amplitude of the modulating wave using a pre-stored table of discrete sinusoidal values ​​combined with the V / F ratio, reducing real-time computational effort and improving system response. A timer generates a high-frequency triangular carrier wave and compares it with the modulating wave in real time, generating a high-quality SPWM pulse train and ensuring the waveform quality of the output signal. Dynamically calculating the dead time based on the output frequency effectively avoids short-circuiting of the upper and lower bridge arms, improving system safety and reliability.

[0012] As a preferred embodiment of the technical solution of the present invention, the target frequency calculation formula is:

[0013] Where f is the target frequency and P is the number of motor pole pairs; Dead time calculation formula:

[0014] Where, is the dead time, is the safety factor.

[0015] As a preferred embodiment of the technical solution of the present invention, the DSP processor includes a V / F simulation module, an SPWM generation module and a phase angle simulation module; the V / F simulation module and the phase angle simulation module are respectively connected to the SPWM generation module; The V / F simulation module is used to calculate the modulation wave amplitude in real time based on the V / F ratio and target frequency issued by the main control module and input it into the SPWM generation module. It is also used to receive the actual voltage and actual frequency feedback from the detection module, calculate the V / F deviation, and dynamically update the modulation scale coefficient based on the V / F deviation through the PID algorithm. The modulation wave amplitude is adjusted according to the updated modulation scale coefficient and input into the SPWM generation module. The phase angle simulation module is used to configure the phase register according to the target phase offset set by the main control module; it is also used to receive the time difference feedback from the detection module and calculate the actual phase offset based on the time difference, and calculate the phase deviation between the target phase offset and the actual phase offset, and dynamically correct the value of the phase register based on the phase deviation; The SPWM generation module is used to generate an SPWM signal according to the modulation wave amplitude output by the V / F simulation module and the phase register set by the phase angle simulation module.

[0016] The V / F simulation module dynamically updates the modulation scale factor using a PID algorithm, effectively compensating for system errors and improving V / F control accuracy, ensuring the output voltage-frequency ratio meets the required relationship. The phase angle simulation module dynamically corrects the phase register value based on the phase difference, achieving precise phase control and improving the accuracy of phase simulation. The coordinated operation of these three modules enables the system to simultaneously and precisely control frequency, voltage, and phase, comprehensively improving the quality of the analog signal.

[0017] As a preferred embodiment of the technical solution of the present invention, the V / F simulation module limits the amplitude of the modulation wave to not exceed a first percentage of the carrier amplitude. When the limit is exceeded, the V / F ratio is automatically reduced and an alarm is issued. The phase angle simulation module converts the target phase offset set by the main control module into the hardware register value of the three-phase ePWM channel and writes it into the ePWM phase register of the DSP processor; The phase angle simulation module is also used to automatically and synchronously update the dead time according to the target frequency.

[0018] The V / F simulation module's modulation amplitude limit and over-limit handling mechanism prevents distortion caused by excessive modulation amplitude and ensures output signal quality. The phase angle simulation module converts the target phase offset into a hardware register value, improving the accuracy and real-time performance of phase control. Automatically and synchronously updating the dead time based on the current frequency ensures system stability and reliability at different frequencies.

[0019] As a preferred embodiment of the technical solution of the present invention, the modulation wave amplitude calculation formula is:

[0020] Where k is the modulation ratio coefficient;

[0021] Where, is the V / F deviation, is the target V / F ratio, is the actual V / F ratio;

[0022] Where, is the modulation ratio coefficient before adjustment, is the adjusted modulation ratio coefficient, is the proportional term, is the integral term, is the differential term.

[0023] As a preferred embodiment of the technical solution of the present invention, the process of phase angle detection is as follows: The detection module uses a square wave shaping circuit to shape the waveform of the three-phase AC voltage signal output by the inverter module, outputting two sets of square wave signals PL1L2 and PL2L3. It also measures the time interval DT1 between the first falling edge of the square wave signal PL2L3 and the first falling edge of the square wave signal PL1L2, as well as the time interval DT2 between the first falling edge of the square wave signal PL2L3 and the second falling edge of the square wave signal PL2L3. DT1 and DT2 are fed back to the phase simulation module. The phase simulation module calculates the actual phase offset according to the formula Φ = (DT1 / DT2) × 180°.

[0024] The detection module uses a square-wave shaping circuit to process the three-phase AC voltage signal, accurately acquiring phase information and improving phase detection accuracy. By measuring specific time intervals and calculating the actual phase angle, the method is simple and effective, reducing system complexity and cost.

[0025] As a preferred embodiment of the technical solution of the present invention, the signal generator further includes a power supply module for supplying power to the main control module, the DSP processor and the inverter module respectively; the three-phase AC voltage signal input lines are L1, L2 and L3 respectively; The square wave shaping circuit includes a diode D1, a diode D2, a photocoupler U1 and a photocoupler U2; the signal input line L1 is connected to the diode anode of the photocoupler U1 through the diode D1 and the resistor R1 in sequence, the diode cathode of the photocoupler U1 is connected to the diode anode of the photocoupler U2, the signal input line L2 is connected to the diode cathode of the photocoupler U1, the signal input line L3 is connected to the diode cathode of the photocoupler U2 through the diode D2 and the resistor R2 in sequence, and the connection point of the diode D1 and the resistor R1 is connected through the resistor R5 and the capacitor C1. Connected to the cathode of the diode of the photoelectric coupler U1, the connection point of the diode D2 and the resistor R2 is connected to the anode of the diode of the photoelectric coupler U2 through the resistor R6 and the capacitor C2, the transistor collector of the photoelectric coupler U1 outputs the wave signal PL1L2, and the transistor collector of the photoelectric coupler U2 outputs the wave signal PL2L3; the transistor collector of the photoelectric coupler U1 is connected to the power module through the resistor R3, and the transistor collector of the photoelectric coupler U2 is connected to the power module through the resistor R4, and the transistor emitter of the photoelectric coupler U1 and the transistor emitter of the photoelectric coupler U2 are both grounded.

[0026] The use of optocouplers achieves electrical isolation of the signal, further improving the system's anti-interference capability. Reasonable configuration of resistor and capacitor parameters ensures the signal shaping effect and circuit stability.

[0027] As a preferred embodiment of the technical solution of the present invention, a discrete value table of a sine function of one cycle is stored in the DSP processor; The SPWM generation module reads discrete values ​​from a pre-stored sine function discrete value table by index, calculates the instantaneous amplitude based on the modulation wave amplitude, and aligns the phase offset of the three-phase modulation wave by force using the phase register to generate the modulation wave. A symmetrical triangular carrier is generated using a DSP timer in up / down counting mode, and the instantaneous amplitude of the modulation wave is compared with the carrier amplitude in real time to generate an SPWM pulse sequence. A delay is added to the upper and lower bridge arm signals of the SPWM signal through the DB module of the DSP processor.

[0028] Pre-storing a table of discrete values ​​for the sine function and accessing them by index reduces the computational burden on the DSP processor and improves system efficiency. Using an up / down counting mode to generate a symmetrical triangular carrier wave and comparing the modulated wave with the carrier wave in real time, the resulting SPWM pulse sequence is more accurate and improves output signal quality. The delay added to the DB module effectively prevents short-circuits in power devices, ensuring safe system operation.

[0029] As a preferred embodiment of the technical solution of the present invention, the inverter module boosts the isolated signal to the IGBT drive standard voltage through the level conversion circuit; the inverter module includes an inverter processing unit provided with six IGBT units, each IGBT is connected to a freewheeling diode, the built-in drive logic of the inverter processing unit automatically inserts the dead time, and the dead time value is configured through the DB module of the DSP processor; three pairs of complementary SPWM signals are distributed to the six IGBT units of the inverter processing unit, when the SPWM signal is high, the IGBT gate is applied with the IGBT drive standard voltage, the IGBT is turned on, and the current flows from the DC bus to the load, when the SPWM signal is low, the IGBT gate voltage drops to 0V, the IGBT is turned off within the set time, and the freewheeling diode provides a current path for the inductive load; through SPWM modulation, the alternating conduction of the three pairs of IGBT units generates an equivalent sinusoidal wave voltage.

[0030] The inverter module utilizes an inverter processing unit with built-in drive logic that automatically inserts dead time, simplifying circuit design and improving system integration and reliability. The alternating conduction of six IGBT units generates an equivalent sinusoidal voltage, accurately simulating tachometer sensor signals and meeting testing requirements. The freewheeling diode provides a current path for inductive loads, protecting power devices and extending system life.

[0031] In a second aspect, the technical solution of the present invention further provides a method for controlling an aircraft engine speed signal generator, comprising the following steps: The main control module receives the tachometer sensor model and target speed input by the user, matches the corresponding target voltage, motor pole pair number and phase difference parameters according to the preset model database; and calculates the target frequency; The DSP processor calculates the initial modulation wave amplitude based on the target voltage-frequency ratio, configures the DSP's phase register based on the target phase offset, sets the initial phase offset of the three-phase SPWM waveform, and generates three SPWM signals through natural sampling based on the modulation wave amplitude and phase register values. The inverter module converts the SPWM signal into a level and drives the inverter processing unit to generate a three-phase AC voltage signal. The detection module collects the actual output voltage, frequency and time difference used to calculate the actual phase offset in real time and feeds them back to the DSP processor; The DSP processor calculates the V / F deviation based on the actual voltage and frequency and dynamically updates the modulation wave amplitude through the PID algorithm; calculates the actual phase offset based on the detected time difference, and adjusts the phase register value based on the phase deviation between the actual phase offset and the target phase offset.

[0032] This control method automates the entire process, from user input to signal output, offering simple and convenient operation and improved testing efficiency. By dynamically updating the modulation amplitude and adjusting the phase register value through the PID algorithm, precise control and real-time adjustment of the output signal are achieved, ensuring the accuracy and stability of the analog signal.

[0033] It can be seen from the above technical solutions that the present application has the following advantages: according to the test requirements input by the user, the signals of tachometer sensors of different models can be accurately simulated. When detecting the tachometer indicator, there is no need to use a new tachometer sensor as the input standard, which avoids the test error introduced by the performance error of the sensor itself, thereby being able to more accurately evaluate the actual performance of the tachometer indicator and reduce the misjudgment of the performance of the tachometer indicator. The signal generator has a built-in tachometer sensor model database, which can automatically match the corresponding frequency, voltage, phase and other parameters according to the tachometer sensor model input by the user. When it is necessary to detect a variety of different models of tachometer indicators, it is only necessary to select the corresponding sensor model in the main control module to generate the corresponding analog signal. There is no need to frequently replace tachometer sensors of different specifications, which greatly simplifies the operation process and improves the detection efficiency.

[0034] Eliminating the need to stock multiple tachometer sensor spare parts reduces spare parts inventory, lowering procurement and management costs. The streamlined process also reduces labor and time costs, ultimately lowering the overall cost of tachometer indicator testing. The detection module measures the three-phase AC signal output by the inverter module in real time and feeds this data back to the main control module, forming a closed-loop control loop. This enables the signal generator to adjust parameters based on actual output conditions, ensuring a more stable and accurate analog signal, further improving detection reliability and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for the description. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0036] Figure 1 This is a block diagram of a signal generator provided by an embodiment of the present invention.

[0037] Figure 2 This is the overall framework diagram of phase detection.

[0038] Figure 3 This is the square wave shaping circuit diagram.

[0039] Figure 4 Schematic diagram of three-phase AC voltage and square wave shaping.

[0040] Figure 5 Schematic diagram of phase calculation.

[0041] Figure 6 This is the main circuit power rectifier circuit diagram.

[0042] Figure 7 This is the optocoupler isolation circuit diagram for the signal.

[0043] Figure 8 A flowchart of a method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the application objectives, features, and advantages of this application more obvious and easy to understand, the technical solutions protected by this application will be clearly and completely described below using specific embodiments and drawings. Obviously, the embodiments described below are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0045] like Figure 1 As shown, an embodiment of the present invention provides an aircraft engine speed signal generator, comprising a main control module, the main control module being connected to a DSP processor, the DSP processor being connected to an inverter module via a signal isolation module, and the inverter module being connected to a detection module; The main control module receives the test requirements input by the user, selects and determines the tachometer sensor model to be simulated based on the test requirements, and has a built-in tachometer sensor model database. The main control module automatically matches the frequency, voltage, and phase parameters in the tachometer sensor model database according to the tachometer sensor model and sends them to the DSP processor; The DSP processor receives the parameters sent by the main control module and generates an SPWM signal through a timer. The timer is configured in a cyclic mode. By changing the initial value of the timer, the period of the PWM signal is changed, that is, the output frequency of the PWM waveform is changed. The signal isolation module electrically isolates the SPWM waveform output by the DSP processor; The inverter module converts the isolated SPWM waveform into a three-phase AC signal and outputs it; The detection module measures the data of the three-phase AC signal output by the inverter module in real time and feeds the data back to the main control module to form a closed-loop control.

[0046] In some embodiments, the main control module receives the tachometer sensor model and the target speed through the user interface, matches the number of motor pole pairs according to the tachometer sensor model database, converts the target speed into a target frequency, obtains the target voltage and V / F ratio according to a preset V / F curve table, sets the target phase offset of the three-phase SPWM waveform, and transmits the target frequency, V / F ratio, and target phase offset to the DSP processor.

[0047] The main control module selects and determines the tachometer sensor model to be simulated, decomposes the instruction requirements into F (frequency), V / F ratio (power to frequency ratio), Φ (phase offset) parameters and transmits them to the corresponding module in the DSP processor; the SPWM waveform generated by the DSP processor is transmitted to the inverter module through the signal isolator module, and the inverted and rectified three-phase AC signal is converted into a tachometer simulation signal with a certain frequency, a certain voltage to frequency ratio, and a certain phase angle; the detection module measures the frequency, voltage, current and phase data and feeds them back to the main control module for closed-loop control to ensure that the final output tachometer simulation signal meets the set requirements In some embodiments, the DSP processor reads discrete values ​​from a pre-stored sine function discrete value table, calculates the instantaneous amplitude of the modulation wave in combination with the V / F ratio, generates a triangular carrier through a timer, compares the modulation wave and the carrier in real time, and outputs a high level when the instantaneous amplitude of the modulation wave is greater than the carrier amplitude, otherwise outputs a low level to generate an SPWM pulse sequence; and calculates the dead time according to the target frequency, and loads the calculated dead time value in real time through the DB module.

[0048] Target frequency calculation formula:

[0049] Where f is the target frequency, P is the number of motor pole pairs (the number of pole pairs of the motor's rotating magnetic field); Dead time calculation formula:

[0050] Where, is the dead time, is the safety factor.

[0051] This system uses a DSP timer to generate precise SPWM signals. The timer is configured in cyclic mode. By changing the initial value of the timer, the period of the PWM signal can be changed, which changes the output frequency of the PWM waveform, up to 4kHz.

[0052] In some embodiments, the DSP processor includes a V / F simulation module, an SPWM generation module, and a phase angle simulation module; the V / F simulation module and the phase angle simulation module are respectively connected to the SPWM generation module; The V / F simulation module is used to calculate the modulation wave amplitude in real time based on the V / F ratio and target frequency issued by the main control module and input it into the SPWM generation module. It is also used to receive the actual voltage and actual frequency feedback from the detection module, calculate the V / F deviation, and dynamically update the modulation scale coefficient based on the V / F deviation through the PID algorithm. The modulation wave amplitude is adjusted according to the updated modulation scale coefficient and input into the SPWM generation module. The phase angle simulation module is used to configure the phase register according to the target phase offset set by the main control module; it is also used to receive the time difference feedback from the detection module and calculate the actual phase offset based on the time difference, and calculate the phase deviation between the target phase offset and the actual phase offset, and dynamically correct the value of the phase register based on the phase deviation; The SPWM generation module is used to generate an SPWM signal according to the modulation wave amplitude output by the V / F simulation module and the phase register set by the phase angle simulation module.

[0053] The V / F analog module limits the modulation wave amplitude to no more than the first percentage of the carrier amplitude. When the limit is exceeded, the V / F ratio is automatically reduced and an alarm is issued; The phase angle simulation module converts the target phase offset set by the main control module into the hardware register value of the three-phase ePWM channel and writes it into the ePWM phase register of the DSP processor; The phase angle simulation module is also used to automatically and synchronously update the dead time according to the target frequency.

[0054] The calculation formula of modulation wave amplitude is:

[0055] Where k is the modulation ratio coefficient;

[0056] Where, is the V / F deviation, is the target V / F ratio, is the actual V / F ratio;

[0057] Where, is the modulation ratio coefficient before adjustment, is the adjusted modulation ratio coefficient, is the proportional term, is the integral term, is the differential term.

[0058] The phase-angle simulation module is a custom-written phase-angle setting program. By setting the comparison mode for the three channels within the DSP, loading the comparison values ​​for the three phase differences, and setting the output value of each comparison channel to two different flips, it can control the conduction of the upper and lower MOS transistors. By setting the dead time, the two MOS transistors on a bridge arm can be turned on at different times to protect them from damage. The program adjusts the phase difference between the three SPWM waveforms in the DSP module, with an adjustable range of 0 to 360 degrees. Phase detection is achieved through the following method: like Figure 2 As shown, the detection module uses a square wave shaping circuit to perform waveform shaping on the three-phase AC voltage signal output by the inverter module, and outputs two sets of square wave signals PL1L2 and PL2L3; and measures the time interval DT1 between the first falling edge of the square wave signal PL2L3 and the first falling edge of the square wave signal PL1L2, and the time interval DT2 between the first falling edge of the square wave signal PL2L3 and the second falling edge of the square wave signal PL2L3; and feeds DT1 and DT2 back to the phase simulation module; The phase simulation module calculates the actual phase offset according to the formula Φ = (DT1 / DT2) × 180°. Figure 4 It is a schematic diagram of three-phase AC voltage and square wave shaping. Figure 5 Schematic diagram of phase calculation.

[0059] An A / D module with a sampling rate of 1 Msps is used to measure the time intervals between DT1 and DT2. The time measurement error meets the measurement requirements of an AC signal with a maximum frequency of 1 kHz. The measurement accuracy of the phase angle is calculated to be no greater than 0.05°.

[0060] In some embodiments, the signal generator further includes a power supply module for supplying power to the main control module, the DSP processor, and the inverter module respectively; the three-phase AC voltage signal input lines are L1, L2, and L3 respectively; like Figure 3As shown, the square wave shaping circuit includes a diode D1, a diode D2, a photocoupler U1 and a photocoupler U2; the signal input line L1 is connected to the diode anode of the photocoupler U1 through the diode D1 and the resistor R1 in sequence, the diode cathode of the photocoupler U1 is connected to the diode anode of the photocoupler U2, the signal input line L2 is connected to the diode cathode of the photocoupler U1, the signal input line L3 is connected to the diode cathode of the photocoupler U2 through the diode D2 and the resistor R2 in sequence, and the connection point between the diode D1 and the resistor R1 is connected through the resistor R5 and the capacitor C 1 is connected to the cathode of the diode of the photocoupler U1, the connection point of the diode D2 and the resistor R2 is connected to the anode of the diode of the photocoupler U2 through the resistor R6 and the capacitor C2, the transistor collector of the photocoupler U1 outputs the wave signal PL1L2, and the transistor collector of the photocoupler U2 outputs the wave signal PL2L3; the transistor collector of the photocoupler U1 is connected to the power module through the resistor R3, and the transistor collector of the photocoupler U2 is connected to the power module through the resistor R4. The transistor emitter of the photocoupler U1 and the transistor emitter of the photocoupler U2 are both grounded.

[0061] L1, L2, and L3 serve as signal input circuits, while D1 and D2 work with L1 and L2, respectively, to perform rectification. When the input signal is AC or contains a negative half-cycle, D1 and D2, following the unidirectional conductivity of the diodes, perform rectification, blocking the negative half-cycle signal and allowing only the positive half-cycle or signals that match a specific direction to pass, resulting in a unidirectional pulse signal.

[0062] R1 and R6 limit the current flowing into D1 and D2, respectively, preventing excessive current from damaging subsequent circuits. C1 and C2 form an RC filter circuit, which removes high-frequency noise and clutter from the signal, making the rectified pulse signal smoother and providing a relatively pure input signal for the optocoupler.

[0063] Optocouplers typically consist of a light-emitting diode (LED) and a photosensitive element (such as a phototransistor). When a rectified and filtered signal is input to the input side of U1 or U2 (where the LEDs are located), if the input signal reaches a certain level, the LEDs will illuminate. The light signal emitted by the LEDs is received by the corresponding photosensitive elements, whose electrical characteristics change with light intensity, generating corresponding changes in the electrical signal at the output side. U1's input side receives the rectified and filtered signal from channel L1. Using the principle of optocoupler, it converts the input electrical signal into an optical signal and then back into an electrical signal, isolating and shaping the input signal and outputting it as a square wave signal PL1L2. U2 operates similarly to U1, processing the rectified and filtered signals from channels L2 and L3 and outputting square wave signals PL2L3. Due to its electrical isolation properties, optocouplers not only shape the input signal but also effectively isolate the electrical connection between the input and output circuits, enhancing the circuit's anti-interference capability. R3 is connected to the output end of U1, and R4 is connected to the output end of U2. Their main function is to limit the current output from the optocoupler to the subsequent load or other circuits, preventing damage to the load or other circuit components connected to PL1L2 and PL2L3 due to excessive current, and playing the role of current limiting protection.

[0064] In some embodiments, a discrete value table of a sine function for one period is stored in the DSP processor; The SPWM generation module reads discrete values ​​from a pre-stored sine function discrete value table by index, calculates the instantaneous amplitude based on the modulation wave amplitude, and aligns the phase offset of the three-phase modulation wave by force using the phase register to generate the modulation wave. A symmetrical triangular carrier is generated using a DSP timer in up / down counting mode, and the instantaneous amplitude of the modulation wave is compared with the carrier amplitude in real time to generate an SPWM pulse sequence. A delay is added to the upper and lower bridge arm signals of the SPWM signal through the DB module of the DSP processor.

[0065] In some embodiments, the inverter module boosts the isolated signal to the IGBT drive standard voltage through a level conversion circuit; the inverter module includes an inverter processing unit provided with six IGBT units, each IGBT is connected to a freewheeling diode, the built-in drive logic of the inverter processing unit automatically inserts dead time, and the dead time value is configured through the DB module of the DSP processor; three pairs of complementary SPWM signals are distributed to the six IGBT units of the inverter processing unit, when the SPWM signal is high, the IGBT drive standard voltage is applied to the IGBT gate, the IGBT is turned on, and current flows from the DC bus to the load, when the SPWM signal is low, the IGBT gate voltage drops to 0V, the IGBT is turned off within the set time, and the freewheeling diode provides a current path for the inductive load; through SPWM modulation, the alternating conduction of the three pairs of IGBT units generates an equivalent sinusoidal wave voltage.

[0066] The inverter processing unit (IPU) is the core unit of the inverter circuit in the inverter module. This module features low saturation voltage drop, rich protection functions, a rated voltage of 600V, and a rated current of 15 to 75A, making it suitable for low-frequency inverter systems.

[0067] The inverter processing unit houses gate drive control circuitry, fault detection, and protection circuitry, and utilizes an IGBT chip with a current sensor. The built-in IGBT chip contains numerous small units that function as current sensors. The signals from these units are fed back to a comparator to detect the IGBT's main current.

[0068] The power module of this device is a DC power supply generated by the main circuit power supply after bridge full-wave rectification and capacitor filtering, which serves as the DC power supply for the inverter circuit. To ensure system safety, a 5A fuse is connected in series at the AC power input. The main circuit power rectifier circuit is as follows: Figure 6 shown.

[0069] It should be noted that the signal isolation module includes a signal optical coupling isolation circuit such as Figure 7 shown.

[0070] The actual operation process is as follows: a) Connect the signal generator to the tachometer indicator to be measured, and turn on the power switch of the signal indicator; b) Enter the LCD screen selection menu, select the "Simulation Speed" button to start the simulation system; c) In the "Simulation Speed ​​Interface", first set the target output value characteristics (determine the ratio between voltage and frequency values), and then output the target value in single points or steps as required; d) The motor confirms the execution button on the LCD screen and outputs the analog speed value in sequence. When the stable prompt indicator light is always on, it means that the analog speed signal output is completed. At this time, you can observe the analog speed value, three-wire phase-to-phase voltage and output frequency on the LCD screen.

[0071] e) You can also switch to manual mode through the program control mode on the LCD screen, and achieve continuous output of analog speed signals through the external manual knob. The output range is 0 to 5000 rpm, with a tolerance of ±1 rpm and a resolution of up to 0.01 rpm.

[0072] like Figure 8 As shown, an embodiment of the present invention further provides a method for controlling an aircraft engine speed signal generator, comprising the following steps: S1. The main control module receives the tachometer sensor model and target speed input by the user, matches the corresponding target voltage, motor pole pair number and phase difference parameters according to the preset model database; and calculates the target frequency; S2, the DSP processor calculates the initial modulation wave amplitude according to the target voltage and frequency ratio, configures the DSP phase register according to the target phase offset, sets the initial phase offset of the three-phase SPWM waveform, and generates three SPWM signals through natural sampling method based on the modulation wave amplitude and phase register value; S3, the inverter module converts the SPWM signal into a level and drives the inverter processing unit to generate a three-phase AC voltage signal; S4, the detection module collects the actual voltage and frequency output in real time and the time difference used to calculate the actual phase offset and feeds it back to the DSP processor; S5, DSP processor calculates V / F deviation based on actual voltage and frequency and dynamically updates the modulation wave amplitude through PID algorithm; calculates actual phase offset based on detected time difference, and adjusts the phase register value based on the phase deviation between actual phase offset and target phase offset.

[0073] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An aircraft engine speed signal generator, characterized in that: It includes a main control module, the main control module is connected to a DSP processor, the DSP processor is connected to an inverter module through a signal isolation module, and the inverter module is connected to a detection module; The main control module receives the test requirements input by the user, selects and determines the tachometer sensor model to be simulated based on the test requirements, and has a built-in tachometer sensor model database. The main control module automatically matches the frequency, voltage, and phase parameters in the tachometer sensor model database according to the tachometer sensor model and sends them to the DSP processor; The DSP processor receives the parameters sent by the main control module and generates SPWM signals through the timer; the timer is configured in a cyclic mode, and the period of the PWM signal is changed by changing the initial value of the timer; The signal isolation module electrically isolates the SPWM waveform output by the DSP processor; The inverter module converts the isolated SPWM waveform into a three-phase AC signal and outputs it; The detection module measures the data of the three-phase AC signal output by the inverter module in real time and feeds the data back to the main control module to form a closed-loop control.

2. The aircraft engine speed signal generator according to claim 1, characterized in that: The main control module receives the tachometer sensor model and target speed through the user interface, matches the motor pole pair number according to the tachometer sensor model database, converts the target speed into the target frequency, obtains the target voltage and V / F ratio according to the preset V / F curve table, sets the target phase offset of the three-phase SPWM waveform, and transmits the target frequency, V / F ratio, and target phase offset to the DSP processor.

3. The aircraft engine speed signal generator according to claim 2, characterized in that: The DSP processor reads discrete values ​​from the pre-stored sine function discrete value table, calculates the instantaneous amplitude of the modulation wave in combination with the V / F ratio, generates a triangular carrier through the timer, and compares the modulation wave and the carrier in real time. When the instantaneous amplitude of the modulation wave is greater than the carrier amplitude, it outputs a high level, otherwise it outputs a low level to generate an SPWM pulse sequence; and calculates the dead time according to the target frequency, and loads the calculated dead time value in real time through the DB module.

4. The aircraft engine speed signal generator according to claim 3, characterized in that: The DSP processor includes a V / F simulation module, an SPWM generation module and a phase angle simulation module; the V / F simulation module and the phase angle simulation module are respectively connected to the SPWM generation module; The V / F simulation module is used to calculate the modulation wave amplitude in real time based on the V / F ratio and target frequency issued by the main control module and input it into the SPWM generation module. It is also used to receive the actual voltage and actual frequency feedback from the detection module, calculate the V / F deviation, and dynamically update the modulation scale coefficient based on the V / F deviation through the PID algorithm. The modulation wave amplitude is adjusted according to the updated modulation scale coefficient and input into the SPWM generation module. The phase angle simulation module is used to configure the phase register according to the target phase offset set by the main control module; it is also used to receive the time difference feedback from the detection module and calculate the actual phase offset based on the time difference, and calculate the phase deviation between the target phase offset and the actual phase offset, and dynamically correct the value of the phase register based on the phase deviation; The SPWM generation module is used to generate an SPWM signal according to the modulation wave amplitude output by the V / F simulation module and the phase register set by the phase angle simulation module.

5. The aircraft engine speed signal generator according to claim 4, characterized in that: The V / F analog module limits the modulation wave amplitude to no more than the first percentage of the carrier amplitude. When the limit is exceeded, the V / F ratio is automatically reduced and an alarm is issued; The phase angle simulation module converts the target phase offset set by the main control module into the hardware register value of the three-phase ePWM channel and writes it into the ePWM phase register of the DSP processor; The phase angle simulation module is also used to automatically and synchronously update the dead time according to the target frequency.

6. The aircraft engine speed signal generator according to claim 5, characterized in that: The process of phase angle detection is as follows: The detection module uses a square wave shaping circuit to shape the waveform of the three-phase AC voltage signal output by the inverter module, outputting two sets of square wave signals PL1L2 and PL2L3. It also measures the time interval DT1 between the first falling edge of the square wave signal PL2L3 and the first falling edge of the square wave signal PL1L2, as well as the time interval DT2 between the first falling edge of the square wave signal PL2L3 and the second falling edge of the square wave signal PL2L3. DT1 and DT2 are fed back to the phase simulation module. The phase simulation module calculates the actual phase offset according to the formula Φ = (DT1 / DT2) × 180°.

7. The aircraft engine speed signal generator according to claim 6, characterized in that: The signal generator also includes a power supply module that supplies power to the main control module, DSP processor and inverter module respectively; the three-phase AC voltage signal input lines are L1, L2 and L3 respectively; The square wave shaping circuit includes a diode D1, a diode D2, a photocoupler U1 and a photocoupler U2; the signal input line L1 is connected to the diode anode of the photocoupler U1 through the diode D1 and the resistor R1 in sequence, the diode cathode of the photocoupler U1 is connected to the diode anode of the photocoupler U2, the signal input line L2 is connected to the diode cathode of the photocoupler U1, the signal input line L3 is connected to the diode cathode of the photocoupler U2 through the diode D2 and the resistor R2 in sequence, and the connection point of the diode D1 and the resistor R1 is connected through the resistor R5 and the capacitor C1. Connected to the cathode of the diode of the photoelectric coupler U1, the connection point of the diode D2 and the resistor R2 is connected to the anode of the diode of the photoelectric coupler U2 through the resistor R6 and the capacitor C2, the transistor collector of the photoelectric coupler U1 outputs the wave signal PL1L2, and the transistor collector of the photoelectric coupler U2 outputs the wave signal PL2L3; the transistor collector of the photoelectric coupler U1 is connected to the power module through the resistor R3, and the transistor collector of the photoelectric coupler U2 is connected to the power module through the resistor R4, and the transistor emitter of the photoelectric coupler U1 and the transistor emitter of the photoelectric coupler U2 are both grounded.

8. The aircraft engine speed signal generator according to claim 7, characterized in that: A discrete value table of a sine function of one cycle is stored in the DSP processor; The SPWM generation module reads discrete values ​​from a pre-stored sine function discrete value table by index, calculates the instantaneous amplitude based on the modulation wave amplitude, and aligns the phase offset of the three-phase modulation wave by force using the phase register to generate the modulation wave. A symmetrical triangular carrier is generated using a DSP timer in up / down counting mode, and the instantaneous amplitude of the modulation wave is compared with the carrier amplitude in real time to generate an SPWM pulse sequence. Signal delay is added to the upper and lower bridge arms of the SPWM signal through the DB module of the DSP processor.

9. The aircraft engine speed signal generator according to claim 8, characterized in that: The inverter module boosts the isolated signal to the IGBT drive standard voltage through a level conversion circuit; the inverter module includes an inverter processing unit equipped with six IGBT units, each of which is connected to a freewheeling diode. The built-in drive logic of the inverter processing unit automatically inserts dead time, and the dead time value is configured through the DB module of the DSP processor; three pairs of complementary SPWM signals are distributed to the six IGBT units of the inverter processing unit. When the SPWM signal is at a high level, the IGBT drive standard voltage is applied to the IGBT gate, the IGBT is turned on, and current flows from the DC bus to the load. When the SPWM signal is at a low level, the IGBT gate voltage drops to 0V, the IGBT is turned off within the set time, and the freewheeling diode provides a current path for the inductive load; through SPWM modulation, the alternating conduction of the three pairs of IGBT units generates an equivalent sinusoidal wave voltage.

10. A control method for an aircraft engine speed signal generator, characterized in that: The following steps are involved: The main control module receives the tachometer sensor model and target speed input by the user, matches the corresponding target voltage, motor pole pair number and phase difference parameters according to the preset model database; and calculates the target frequency; The DSP processor calculates the initial modulation wave amplitude based on the target voltage-frequency ratio, configures the DSP's phase register based on the target phase offset, sets the initial phase offset of the three-phase SPWM waveform, and generates three SPWM signals through natural sampling based on the modulation wave amplitude and phase register values. The inverter module converts the SPWM signal into a level and drives the inverter processing unit to generate a three-phase AC voltage signal. The detection module collects the actual output voltage, frequency and time difference used to calculate the actual phase offset in real time and feeds them back to the DSP processor; The DSP processor calculates the V / F deviation based on the actual voltage and frequency and dynamically updates the modulation wave amplitude through the PID algorithm; calculates the actual phase offset based on the detected time difference, and adjusts the phase register value based on the phase deviation between the actual phase offset and the target phase offset.

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