A turboshaft engine three-engine torque matching controller and control method

Abstract

The present invention discloses a three-engine torque matching controller and control method for a turboshaft engine. The method enables each engine to adjust its own gas generator command speed according to its own output torque and the output torque of the other two engines, thereby achieving equal torque output for each engine. The three-engine torque matching control method enables each engine to receive the flameout signal of the other two engines, and the matching circuit can be reconstructed when an engine fails and flames out. Compared with the existing three-engine torque matching technology, the present invention can balance the torque output of the three engines, avoiding the problem of low output torque of the last engine when starting in batches. When a single engine fails, the remaining engines can automatically compensate for the power loss caused by the failed engine, and still achieve equal torque output, which has important engineering application value.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engines, and in particular to a three-engine torque matching controller and a control method for a turboshaft engine. Background Art

[0002] Helicopters boast advantages over conventional fixed-wing aircraft, including vertical takeoff and landing, hovering, and lateral flight, making them widely used in a variety of military and civilian applications. Compared to traditional piston engines, turboshaft engines offer a high power-to-weight ratio, excellent reliability, superior economy, and enhanced environmental adaptability, making them widely used in the propulsion systems of medium- and heavy-duty helicopters. Due to the high payload, maneuverability, and safety requirements, some helicopters are equipped with multiple turboshaft engines operating in parallel.

[0003] For helicopters equipped with multiple turboshaft engines, when all engines are operating normally, it is desirable for all engines to share the rotor load equally. This allows all engines to respond to sudden disturbances in transient conditions with nearly identical responses. Furthermore, equal torque output helps prolong the life of the helicopter's transmission system. Given the differences in individual engine performance, if multi-engine torque matching is not implemented, the helicopter's multiple engines will experience uneven torque output, adversely affecting flight safety and transmission life. Therefore, it is necessary to develop a rational multi-engine torque matching control strategy based on the constant speed control law of the turboshaft engine's power turbine to minimize the lifespan of the helicopter's transmission system and improve flight safety. Summary of the Invention

[0004] Purpose of the invention: In response to the problems existing in the above-mentioned background technology, the present invention provides a turboshaft engine torque matching control method, which can balance the torque output of three turboshaft engines and avoid the problem of low output torque of the last engine when starting in batches; when a single engine fails, the remaining engines can automatically compensate for the power loss caused by the failed engine and still achieve equal torque output.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for torque matching control of three engines of a turboshaft engine is disclosed. Each engine adjusts its own gas generator command speed based on its own output torque and the output torques of the other two engines, thereby achieving equal torque output for each engine. The method enables each engine to receive flameout signals from the other two engines, and can reconstruct the matching circuit when an engine fails and flames out. The method adjusts the gas generator command speed of the engine only when the speed difference between the power turbine of the engine and the matching target engine is within a set range, thereby preventing the engine that starts first from reducing its torque output to match the torque of the engine that starts later during the starting phase.

[0007] Preferably, the torque matching control is designed based on a cascade controller consisting of a power turbine speed control loop and a gas generator speed control loop. The cascade controller adopts a PI control rate, and the power turbine speeds Np1, Np2, and Np3 of each engine are used as control objects. The power turbine speed control loop calculates the gas generator command speed Ngd based on the difference between the power turbine command speed Npd and the power turbine actual speed Np, and the gas generator speed control loop calculates the fuel quantity increment ΔWf based on the difference between the gas generator command speed Ngd and the gas generator actual speed Ng. The torque matching controller includes two circuits, both of which adopt a PI control rate, and calculate the two increments of the gas generator command speed based on the difference between the output torque of one of the two adjacent engines and the output torque of the current engine. Taking engine No. 1 as an example, the two increments are and The two increments are added and integrated to obtain the command speed compensation amount ΔNgd1 of the gas turbine of engine No. 1.

[0008] Preferably, each engine receives the power turbine speed and flameout signals from the other two engines. When an engine flames out, the flameout signal flag is set to 1; otherwise, it is set to 0. For any circuit of the torque matching controller, if the absolute value of the power turbine speed difference calculated by that circuit is greater than a specified error err or the sum of the flameout signals is greater than 0, the gas generator command speed increment for that circuit is set to 0.

[0009] Beneficial effects:

[0010] The present invention provides a method for controlling the torque matching of three engines of a turboshaft engine, which can balance the torque output of the three engines and avoid the problem of low output torque of the last engine during batch starting. When a single engine fails, the remaining engines can automatically compensate for the power loss caused by the failed engine and still achieve equal torque output. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the transmission structure of a three-engine helicopter;

[0012] Figure 2 This is the structure diagram of the cascade PI fuel controller;

[0013] Figure 3 This is a logic diagram of the three-engine torque matching controller of the turboshaft engine;

[0014] Figure 4 It is the simulation curve of the flow rate and efficiency change of each engine compressor;

[0015] Figure 5 It is the response curve of key parameters of the engine without torque matching after performance changes;

[0016] Figure 6 It is the simulation result of the key parameters of the torque matching engine after the performance change;

[0017] Figure 7 It is the simulation curve of key parameters of the engine without torque matching during batch starting process;

[0018] Figure 8 It is the simulation curve of key parameters of engine with torque matching during batch starting process;

[0019] Figure 9 It is a simulation curve of key parameters of the torque-matching engine after a single engine failure. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings. It should be understood that the embodiments described herein are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0021] The present invention provides a method for controlling torque matching of three engines of a turboshaft engine, which is specifically as follows:

[0022] Each engine adjusts its own gas generator command speed based on its own output torque and the output torque of the other two engines to achieve equal torque output for each engine; the three-engine torque matching control method allows each engine to receive the flameout signal of the other two engines, and the matching circuit can be reconstructed when an engine fails and shuts down; the three-engine torque matching control method will only adjust the gas generator command speed of its own engine when the power turbine speed difference between the own engine and the matching target engine is within a set range, avoiding the engine that starts first during the starting phase from reducing its torque output to match the torque of the engine that starts later.

[0023] To facilitate public understanding, the technical solution of the present invention is described in detail below through a specific example with reference to the accompanying drawings:

[0024] First, a three-engine turboshaft engine / transmission system / rotor model was established, using this as the control object to design a three-engine torque matching controller. The turboshaft engine was modeled using the component approach, the rotor was modeled using blade element theory, and the transmission mechanism was modeled based on rotor dynamics and elastic mechanics.

[0025] In order to simulate the matching effect of the matching controller after the engine performance changes, the compressor flow and efficiency degradation coefficient C are defined w 、C η :

[0026] W2=C w W 2c P2 / 101325 / (T2 / 288.15) 0.5 (1)

[0027] η=C η η c (2) The symbols in formulas (1) and (2) are defined as follows: W2 is the physical flow rate at the compressor inlet; W 2c is the converted flow rate at the compressor inlet; P2 is the total pressure at the compressor inlet; T2 is the total temperature at the compressor inlet; η c is the isentropic efficiency obtained by interpolation of the compressor characteristic diagram; η is the actual efficiency of the compressor.

[0028] As a bridge between the turboshaft engine and the rotor load, the transmission mechanism needs to transmit the power output by the three parallel turboshaft engines to the rotor on the one hand, and on the other hand, it needs to ensure that in the event of a single engine failure or the last engine fails to start, the normally working engine continues to provide power to the rotor and disconnects the faulty engine or the unstarted engine in time.

[0029] The structural diagram of the transmission mechanism is as follows Figure 1 As shown, it mainly includes a reducer, a transmission shaft, a transmission gear (including a main gear and a sub-gear) and an overrunning clutch. The power turbine output shafts of the three engines are respectively connected to a main transmission shaft through an overrunning clutch, and the main transmission shaft then transmits power to loads such as the rotor and tail rotor.

[0030] like Figure 2As shown in Figure 1, all three turboshaft engines utilize a constant power turbine speed control law and a cascaded PI fuel controller. The fuel controller uses each engine's power turbine speeds Np1, Np2, and Np3 as controlled parameters. The power turbine speed control loop calculates the gas generator command speed Ngd based on the difference between the power turbine command speed Npd and the actual power turbine speed Np. The gas generator speed control loop calculates the engine fuel quantity increment ΔWf based on the difference between the gas generator command speed Ngd and the actual gas generator speed Ng. The mathematical expression for the cascaded PI fuel controller is as follows:

[0031] Ngd=k p1 (Npd-Np)+K i1 ∫(Npd-Np) (3)

[0032] ΔWf=k p2 (Ngd-Ng)+K i2 ∫(Ngd-Ng) (4)

[0033] Where: k p1 and K i1 are the proportional control coefficient and integral control coefficient of the outer loop controller, k p2 and K i2 are the proportional control coefficient and integral control coefficient of the inner loop controller respectively.

[0034] The torque matching controller designed for engine 1 using the torque matching control method for three engines of a turboshaft engine proposed in this invention is as follows: Figure 3 As shown. The controller consists of two circuits, circuit 1 and circuit 2, which respectively correct the torque of engine No. 1 according to the torque difference between engine No. 1 and engine No. 2, and the torque difference between engine No. 1 and engine No. 3. When all three engines are not shut down and the power turbine speed is the same, the controller is equivalent to a traditional bilateral torque matching controller, which can quickly correct the torque difference caused by the state difference between the engines. When the engine is working normally, Figure 3 The flameout signal output is set to 1; after the engine is restarted, the flameout signal returns to 0. If engine #2 experiences a fault and flames out, circuit 1 will no longer reference engine #2 for torque matching, preventing engine #1 from reducing its torque output to match the torque of the faulty engine, which could create a dangerous situation. At this point, the torque matching controller for engine #3 will also stop matching its output torque to engine #2. The entire matching circuit will only connect between engines #1 and #3, excluding the faulty engine #2. To ensure that the engine that starts first during the startup phase does not reduce its torque output to match the torque of the engine that starts later, the torque matching control circuit is only connected when the power turbine speed control error is within the allowable range, err.

[0035] The torque matching controllers of engines No. 2 and No. 3 are similar to those of engine No. 1 and will not be described in detail.

[0036] For three turboshaft engines with the same performance and status working stably in static atmospheric conditions on the ground, such as Figure 4 As shown in the figure, at 5s, the compressor efficiency of engine 1 is reduced by 2% and the flow rate is increased by 5%, and the compressor efficiency of engine 2 is reduced by 3% and the flow rate is reduced by 1% to simulate the dynamic response of the engine when there is no torque matching controller when the engine performance changes. The simulation results are shown in Figure 5 shown.

[0037] Figure 5 Figures (a), (b), and (e) respectively describe the changes in fuel flow, gas generator speed, and power turbine inlet temperature after the engine performance changes under the action of the power turbine constant speed controller. Figure 5 As shown in (f), when the performance of engines 1 and 2 changes at 5s, the total torque output of the three engines increases, so Figure 5 As shown in (c), the power turbine speed surges. At this time, the overrunning clutches of the three engines are all engaged, and the power turbine speeds of the three engines are the same. When an error occurs between the power turbine command speed and the actual speed, the power turbine speed controller adjusts the fuel volume of the three engines to readjust the power turbine speed to 100%. Figure 5 As shown in Figures (c), 5(f), and 5(d), when the power turbine speed returns to 100%, the total output torque of the three engines remains consistent with that before the engine performance change, but there are differences in the output torque of each engine (65.4%, 62.2%, and 60.6%).

[0038] After the states of engines 1 and 2 change as described above, the torque matching controller is turned on at 25 seconds to verify the matching logic of the output torques of the three engines. The simulation results are as follows: Figure 6 shown. Figure 6 (a) and (b) respectively describe the changes in the engine fuel flow and gas generator speed after the torque matching controller is turned on. Figure 6 As shown in (d), after the matching controller is turned on, the output torques of the three engines gradually approach each other, with an error band of ±0.1%, and torque matching is achieved after 5.6s. The output of the matching controller in this process is shown in Figure 6 As shown in (f), the matching controller mainly compensates for the gas generator command speed of engines No. 2 and No. 3, which have lower output torque, while the adjustment of engine No. 1, which has the highest output torque, only occurs in the fine-tuning when the three engines are close to matching. The increase in the output of the torque matching controller of engines No. 2 and No. 3 after matching begins will cause the following Figure 6The total output power shown in (e) increases, resulting in Figure 6 The power turbine speed shown in (c) overshoots, but under the joint action of the power turbine constant speed controller, the power turbine speed enters the error band of ±0.1% after 5.5s. The power turbine speed overshoot in this process is 0.94%. The torque matching has little effect on the power turbine constant speed control loop.

[0039] For three parallel-configured turboshaft engines with the same state and no degradation, start No. 1 and No. 2 engines simultaneously to ground idle state at 0s, and then start No. 3 engine at 50s. The simulation results without torque matching controller are as follows: Figure 7 shown.

[0040] Figure 7 (a) and (b) respectively describe the fuel supply change curve and gas generator speed response curve of the three engines during the starting process. Figure 7 As shown in (c), engines #1 and #2 start simultaneously, accelerating the power turbine speed to 75%. At this point, these two engines are providing all the required rotor power. Then, at 50 seconds, engine #3 starts. At 82.4 seconds, its power turbine speed is accelerated to the same speed as engines #1 and #2. The overrunning clutch switches from disengaged to engaged, and the third engine begins delivering power to the transmission. The power turbine speed surges, but quickly returns to 75% thanks to the power turbine speed controller.

[0041] like Figure 7 As shown in (d), since the No. 3 engine does not need to drive the rotor load when starting, its torque output is significantly lower than that of the No. 1 and No. 2 engines.

[0042] Similarly, for three parallel-configured turboshaft engines with the same status and no performance degradation, start No. 1 and No. 2 engines to ground idle state at 0s, and then start No. 3 engine at 50s. Dynamic simulation is carried out under the condition of introducing torque matching controller. The results are as follows Figure 8 shown.

[0043] like Figure 8 As shown in (c), at 82.23s, the speed difference between the power turbine of engine No. 3 and the other two engines enters the set matching range, so Figure 8 As shown in (d), under the combined action of the torque matching controller and the power turbine constant speed controller, the output torque of engine No. 3 increases, while the output torques of engines No. 1 and No. 2 decrease until the output torques of the three engines reach consistency.

[0044] To verify whether the remaining two engines can compensate for the total output power reduction caused by the failed engine and still achieve output torque matching if there is sufficient power reserve after a single engine fails, for three parallel turboshaft engines with different states (engine No. 1 compressor efficiency reduced by 2% and flow increased by 5%, engine No. 2 compressor efficiency reduced by 3% and flow reduced by 1%, and engine No. 3 performance unchanged), engine No. 1 is shut down at 5 seconds. The simulation results are as follows: Figure 9 shown.

[0045] like Figure 9 As shown in the figure, after engine No. 1 failed and flamed out, its output torque dropped rapidly, causing the total output torque of the three engines to fall below the required rotor torque. This caused a significant drop in rotor speed. Under the action of the power turbine constant speed controller, the fuel flow and torque of engines No. 2 and 3 were increased to compensate for the power loss caused by the failure of engine No. 1. After 6.2 seconds, the rotor speed fell within the ±1% error band. After engine No. 1 failed, the matching controller still achieved torque matching between the remaining two engines. At t = 15.2 seconds, the output torque difference between engines No. 2 and 3 fell within the ±0.1% error band.

[0046] In summary, the three-engine torque matching control method of a turboshaft engine provided by the present invention can balance the torque output of the three engines, avoiding the problem of low output torque of the last engine during batch starting; when a single engine fails, the remaining engines can automatically compensate for the power loss caused by the failed engine, and still achieve equal torque output.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for controlling torque matching of three engines of a turboshaft engine, characterized in that: The following steps are involved: 1) Signal input: For the No. 1 torque matching controller, line 1: the first adder-subtractor receives the power turbine output torque signals Tq1 and Tq2 of the No. 1 engine and the No. 2 engine, and makes a difference between the two power turbine output torque signals, and takes the difference result ΔTq 21 Input the incremental PI controller to calculate and obtain the single-step increment of the speed compensation of the gas generator of engine No. 1 under the influence of engine No.

2. Increment the step Input a first judgement device; The second adder-subtractor receives the No. 1 and No. 2 engine power turbine speed signals Np1 and Np2, and makes a difference between the two power turbine speed signals, and inputs the difference result into the absolute value device to obtain the amplitude ΔNp of the difference between the two power turbine speed signals. 12 , the amplitude ΔNp 12 Input a first judgement device; The first adder receives the flameout signals #1 and #2 of engine No. 1 and engine No. 2, and sums the two flameout signals. It is defined that the flameout signal is 1 if the engine is flameout, and 0 otherwise; the summation result is input into the second judgement unit; For the torque matching controller No. 1, line 2: the first adder and subtractor receives the power turbine output torque signals Tq1 and Tq3 of the No. 1 engine and the No. 3 engine, and makes a difference between the two power turbine output torque signals. The difference result is input into the incremental PI controller for calculation to obtain the single-step increment of the speed compensation of the gas generator of the No. 1 engine under the influence of the No. 3 engine. Increment the step Input a first judgement device; The second adder-subtractor receives the power turbine speed signals Np1 and Np3 of the No. 1 and No. 3 engines, and makes a difference between the two power turbine speed signals. The difference result is input into the absolute value device to obtain the amplitude ΔNp of the difference between the two power turbine speed signals. 13 , the amplitude ΔNp 13 Input a first judgement device; The first adder receives and calculates the flameout signals #1 and #3 of the No. 1 engine and the No. 3 engine, sums the two flameout signals, and inputs the summation result into the second determiner; 2) Judge the calculation results: For torque matching controller No. 1, circuit 1: If the amplitude ΔNp of the input first judgement 12 If the error is less than or equal to the specified error range err, and the sum of the flameout signals input to the second judgement is less than or equal to 0, the single-step increment is not performed. Modify, that is, the output of the second judge otherwise For the torque matching controller circuit 2, if the amplitude ΔNp of the first judgement input is 13 If the error is less than or equal to the specified error range err, and the sum of the flameout signals input to the second judgement is less than or equal to 0, the single-step increment is not performed. Modify, that is, the output of the second judge otherwise 3) Output: Output of two second judges and Input the second adder, the second adder will sum Input the third adder, and then accumulate the sum to obtain the No. 1 engine gas generator speed compensation ΔNgd1, 4) add the No. 1 engine gas generator speed compensation ΔNgd1 to the first N P The output Ngd1 of the speed controller, the first N P The speed controller is located in the first cascade PI fuel controller; Similarly, for the torque matching controller No. 2, circuit 1: the first adder and subtractor receive the power turbine output torque signals Tq1 and Tq2 of the No. 1 and No. 2 engines, the second adder and subtractor receive the power turbine speed signals Np2 and Np1 of the No. 2 and No. 1 engines, and the first adder receives the flameout signals #2 and #1 of the No. 2 and No. 1 engines; For the No. 2 torque matching controller, circuit 2: the first adder and subtractor receive the power turbine output torque signals Tq3 and Tq2 of the No. 3 engine and the No. 2 engine, the second adder and subtractor receive the power turbine speed signals Np2 and Np3 of the No. 2 and No. 3 engines, and the first adder receives the flameout signals #2 and #3 of the No. 2 engine and the No. 3 engine; the No. 2 torque matching controller calculates the speed compensation amount ΔNgd2 of the No. 2 engine gas generator; the speed compensation amount ΔNgd2 of the No. 2 engine gas generator is added to the second N P The output Ngd2 of the speed controller, the second N P The speed controller is located in the second cascade PI fuel controller; Similarly, for the torque matching controller No. 3, circuit 1: the first adder and subtractor receive the power turbine output torque signals Tq1 and Tq3 of the No. 1 and No. 3 engines, the second adder and subtractor receive the power turbine speed signals Np3 and Np1 of the No. 3 and No. 1 engines, and the first adder receives the flameout signals #1 and #3 of the No. 1 and No. 3 engines. For the torque matching controller No. 3, circuit 2: the first adder and subtractor receives the power turbine output torque signals Tq2 and Tq3 of the No. 2 engine and the No. 3 engine, the second adder and subtractor receives the power turbine speed signals Np2 and Np3 of the No. 3 and No. 2 engines, the first adder receives and calculates the flameout signals #2 and #3 of the No. 2 engine and the No. 3 engine; the torque matching controller No. 3 calculates the speed compensation amount ΔNgd3 of the No. 3 engine gas generator; the speed compensation amount ΔNgd3 of the No. 3 engine gas generator is added to the No. 3 engine gas generator. P The output Ngd3 of the speed controller, the third N P The speed controller is located in the third cascade PI fuel controller.

2. A method for controlling torque matching of three engines of a turboshaft engine according to claim 1, characterized in that: In step 3): The single-step increment of the gas generator speed compensation amount of engine No. 1 under the influence of engine No. 2 is added to the single-step increment of the gas generator speed compensation amount of engine No. 1 under the influence of engine No. 3 to obtain the single-step increment of the gas generator speed compensation amount of engine No. 1 under the combined influence of engines No. 2 and 3; In step 3), the single-step increment of the gas generator speed compensation amount of engine No. 2 under the influence of engine No. 1 and the single-step increment of the gas generator speed compensation amount of engine No. 2 under the influence of engine No. 3 are added together to obtain the single-step increment of the gas generator speed compensation amount of engine No. 2 under the combined influence of engine No. 1 and engine No. 3; In step 3), the single-step increment of the gas generator speed compensation amount of engine No. 3 under the influence of engine No. 2 is added to the single-step increment of the gas generator speed compensation amount of engine No. 3 under the influence of engine No. 1 to obtain the single-step increment of the gas generator speed compensation amount of engine No. 3 under the combined influence of engine No. 2 and engine No.

1.

3. A turboshaft engine three-engine torque matching controller, utilizing a turboshaft engine three-engine torque matching control method according to claim 1 or 2, characterized in that: There are three torque matching controllers, No. 1, No. 2 and No.

3. Each torque matching controller includes line 1 and line 2: Both circuit one and circuit two include a first adder-subtractor, an incremental PI controller, a first judger, and a second judger, wherein the first adder-subtractor, the incremental PI controller, the first judger, and the second judger are connected in series in sequence; Circuit 1 and circuit 2 also include a second adder-subtractor, an absolute value device, and a first adder. The second adder-subtractor, the absolute value device, and the first judger are connected in series in sequence, and the first adder and the second judger are connected in series. The output ends of the two second judges are also connected to the second adder, and the output end of the second adder is further connected in series with the third adder and the delay link 1 / z. The output end of the third adder is respectively connected to the first, second and third cascade PI fuel controllers, and the output end of the delay link 1 / z is connected to the third adder.

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