JP2025022161A - Propulsion system and protection device for rotating electrical machine - Google Patents

Abstract

To provide a propulsion system capable of mechanically separating a rotary electric machine having a sign of failure at an arbitrary timing while continuing operation of a prime mover when abnormality of the rotary electric machine is detected and a protection device of a rotary electric machine.SOLUTION: A propulsion system includes a prime mover, a rotary electric machine, a mechanical fuse, a sensor, and a protection device. The rotary electric machine is a permanent magnet field type rotary electric machine having a rotor connected to the prime mover. The mechanical fuse is connected between the prime mover and the rotary electric machine. The sensor monitors a state of the rotary electric machine. The protection device is configured to be capable of applying a torsional vibration torque to the mechanical fuse based on an output of the sensor, the torsional vibration torque causing the mechanical fuse to rupture.SELECTED DRAWING: Figure 1

Description

The present invention relates to a propulsion system, and more specifically to a protection device for a rotating electrical machine that is directly connected to a prime mover such as an engine or turbine.

In recent years, in mobility applications such as ships and aircraft, systems have been developed in which a rotating electric machine is directly connected to a prime mover such as an engine or turbine, such as a hybrid propulsion system that provides power assist and power generation, or shaft power generation. In such a system, if a layer short circuit or bearing abnormality occurs and rotational force continues to be applied from the prime mover, a fire caused by localized high heat or abnormal vibrations may occur in the rotating electric machine, especially in permanent magnet type rotating electric machines, since the field voltage cannot be reduced. Since crew members on ships and aircraft cannot immediately evacuate from the location of a fire, it is desirable to build a system that can disconnect the rotating electric machine when signs of an accident are recognized and take evacuation action by continuing to operate the prime mover.

Generally, it is necessary to provide a mechanism that mechanically separates the engine shaft from the generator shaft in the event of a malfunction; examples of such mechanisms include a shear pin or a clutch mechanism. For example, Patent Document 1 describes a generator that uses a gas turbine as a prime mover, and a structure in which a shear pin is provided between the reducer and the generator to protect the prime mover from overload.

JP 2000-37057 A

However, in cases such as interlayer short circuits or bearing abnormalities, the transient torque at the time of abnormality is small, so the shear pin does not operate. On the other hand, the larger the capacity of the clutch mechanism, the larger and more expensive it becomes, which hinders the application of the system to the mobility applications mentioned above. There is a need for a new method that can disconnect a faulty rotating electric machine from the prime mover at any time before the accident spreads, and continue operating the prime mover, with a system structure that keeps weight and cost from increasing compared to conventional methods.

In view of the above circumstances, the object of the present invention is to provide a propulsion system and a protection device for a rotating electric machine that can mechanically isolate a rotating electric machine showing signs of failure at any time while continuing to operate the prime mover if an abnormality in the rotating electric machine is detected.

A propulsion system according to one aspect of the present invention includes a prime mover, a rotating electric machine, a mechanical fuse, a sensor, and a protection device.
The rotating electric machine is a permanent magnet field type rotating electric machine having a rotor connected to the prime mover.
The mechanical fuse is connected between the prime mover and the rotating electric machine.
The sensor monitors a state of the rotating electric machine.
The protection device is configured to be able to apply a torsional vibration torque to the mechanical fuse, causing the mechanical fuse to break, based on an output of the sensor.

According to the above propulsion system, when an abnormality in the rotating electric machine is detected, a torsional vibration torque that breaks the mechanical fuse is applied to the mechanical fuse, so that a rotating electric machine showing signs of failure can be mechanically disconnected at any time while continuing to operate the prime mover.

The protection device may include a power converter, a protected load, and a controller.
The power converter is connected to the rotating electric machine.
The protected load consumes power generated by the power converter.
The control unit determines whether or not there is an abnormality in the rotating electric machine based on the output of the sensor, and when it determines that there is an abnormality in the rotating electric machine, inputs a control command to the power converter to generate the torsional vibration torque.

The control command may include a torque command value in which the target torque value changes periodically.

The control unit may generate a torque command value that generates a torsional vibration torque having a frequency equivalent to the torsional resonance frequency of the mechanical fuse.

The protection device may further have a first circuit breaker capable of interrupting electrical continuity between the power converter and an electrical load that operates by receiving electrical power generated by the power converter, and the control unit may cause the first circuit breaker to interrupt electrical continuity between the power converter and the electrical load when it determines that the rotating electrical machine is abnormal.

The protection device may further have a second circuit breaker capable of interrupting conduction between the power converter and the protected load, and the control unit may cause the second circuit breaker to interrupt conduction between the power converter and the protected load when it determines that the rotating electric machine is not abnormal.

The rotating electric machine may be a generator or a motor.

The mechanical fuse may be tubular in shape.

The sensor may be a temperature sensor that measures the temperature of the rotating electric machine, or a current sensor that detects the current flowing through the rotating electric machine.

The prime mover may be a jet engine.

A protection device according to one embodiment of the present invention is a protection device for a rotating electric machine having a prime mover, a permanent magnet field type rotating electric machine having a rotor connected to the prime mover, and a mechanical fuse connected between the prime mover and the rotating electric machine, and is equipped with a power converter, a protected load, and a control unit.
The power converter is connected to the rotating electric machine.
The protected load consumes power generated by the power converter.
The control unit determines whether or not there is an abnormality in the rotating electric machine based on the output of a sensor that monitors the condition of the rotating electric machine, and when it determines that there is an abnormality in the rotating electric machine, it inputs a control command to the power converter to generate a torsional vibration torque that breaks the mechanical fuse.

According to the present invention, when an abnormality in a rotating electric machine is detected, the rotating electric machine showing signs of failure can be mechanically disconnected at any time while continuing to operate the prime mover.

1 is a schematic configuration diagram of a propulsion system according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the configuration of a generator. FIG. 4 is a control block diagram of the propulsion system during steady operation control. 1 is a schematic diagram showing a state in which a layer short occurs in electromagnetic coils of a generator wound in the same slot. FIG. FIG. 1 is an equivalent circuit diagram of a permanent magnet generator (PMSG). FIG. 4 is a control block diagram of the propulsion system during protection control. FIG. 4 is a waveform diagram showing an example of power oscillation. FIG. 2 is a diagram illustrating the phase relationship between a prime mover and a generator. FIG. 11 is a diagram showing the relationship between the frequency of vibration torque and the response magnification. FIG. 13 is a diagram showing the relationship between the response torque acting on a mechanical fuse and the generator torque. FIG. 4 is a schematic configuration diagram of a propulsion system according to another embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 is a schematic diagram of a propulsion system 100 according to one embodiment of the present invention. The propulsion system 100 according to this embodiment is applied to a propulsion system installed in an aircraft, for example, and includes a prime mover 10, a generator 20, and a protection device 40.

[Propulsion system overview]
Examples of aircraft equipped with the propulsion system 100 include aircraft equipped with the prime mover 10 as a propulsion device, as well as electric aircraft that drive auxiliary propulsion systems such as fans and propellers with electricity from the generator 20. In this propulsion system, the prime mover 10 rotates a propulsion propeller to obtain thrust for cruising, and the generator 20 is operated with surplus energy to generate an electric load.

The prime mover 10 is, for example, a jet engine having a compressor, a combustor, a turbine, etc. The prime mover 10 drives a thruster 12 such as a propeller or a fan via gears 11, etc., while also driving a generator 20. The prime mover 10 is controlled by a prime mover controller 15 such as a Full Authority Digital Engine Control (FADEC). The prime mover controller 15 controls the fuel supply to the prime mover 10, etc., to maintain the speed by keeping the thruster 12 at a constant rotation speed during cruising.

The generator 20 is a permanent magnet synchronous generator (PMSG) that converts the rotational force of the rotating shaft 10a of the prime mover 10 into electrical energy. FIG. 2 is a schematic diagram showing the configuration of the generator 20. The generator 20 includes a rotor 21 having permanent magnets 21S and 21N, and a stator 22 around which a multi-phase electromagnetic coil is wound.

The multi-phase electromagnetic coil is not particularly limited as long as it is an electromagnetic coil through which two or more alternating currents of different phases flow, and here, a three-phase electromagnetic coil having U, V, and W phases is used. The power generated by the generator 20 is supplied to the power load 50 via a CVCF (Constant Voltage Constant Frequency) or the like. As will be described later, the generator 20 may be a motor that performs power running to support the power of the prime mover 10 (see FIG. 11).

The rotating shaft 20a (rotor 21) of the generator 20 is connected to the rotating shaft 10a of the prime mover 10 via a mechanical fuse 30. The mechanical fuse 30 transmits the rotational driving force of the prime mover 10 to the generator 20. A shear pin (also called a shear pin) is used for the mechanical fuse 30. The mechanical fuse 30 is formed in a tubular shape such as a cylindrical shape, or in a shape that is partially narrowed by providing a constriction in part so that it can be broken by a predetermined torsional vibration torque that is electrically generated in the protection device 40 as described below.

A monitoring sensor 31 is attached to the generator 20 to monitor the state of the generator 20. The monitoring sensor 31 may be a temperature sensor that measures the temperature of the generator 20 or a current sensor that detects the current generated by the generator 20. In this embodiment, the monitoring sensor 31 includes three temperature sensors 31a, 31b, and 31c that are attached to the stator 22 at equal angular intervals, as shown in FIG. 2, for example.

A current sensor 32 that detects the magnitude of the current flowing through the electromagnetic coil is attached between the generator 20 and the protection device 40 (power converter 41). This current sensor 32 is a sensor that feeds back the generator current to the control unit 43 so that the current generated in the generator 20 reaches a target current value. Note that the current sensor 32 may be used as a monitoring sensor 31 instead of or in addition to the temperature sensors 31a to 31c.

The protection device 40 functions as a power generation control device that controls the power generated by the generator 20 during normal operation when there is no abnormality in the generator 20, and has the function of isolating the generator 20 from the prime mover 10 to protect the generator 20 when an abnormality is detected in the generator 20. More specifically, the protection device 40 monitors whether there is an abnormality in the generator 20, supplies the power generated by the generator 20 to the power load when the generator 20 is normal, and generates a power oscillation to break the mechanical fuse 30 and isolate the generator 20 from the prime mover 10 when an abnormality in the generator 20 is detected. The protection device 40 will be described in detail below.

[Protection Device]
The protection device 40 includes a power converter 41 , a protected load 42 , a control unit 43 , a first circuit breaker 51 , and a second circuit breaker 52 .

The power converter 41 is connected to the generator 20 and is a converter that converts the AC power generated by the generator 20 into a predetermined DC power consumed by the power load 50. The power load 50 is a power circuit or power device that operates by receiving the power generated by the power converter 41. Examples of power loads include electrical devices such as fans and pumps installed on the aircraft, as well as air conditioning equipment, batteries, and auxiliary propulsion systems.

The first circuit breaker 51 is a switch capable of interrupting conduction between the power converter 41 and the power load 50. The first circuit breaker 51 is controlled to open and close by the control unit 43, and interrupts conduction between the power converter 41 and the power load 50 when an abnormality is detected in the generator 20, as described below.

The protective load 42 is an element capable of consuming the power generated by the power converter 41 to generate a power oscillation for breaking the mechanical fuse 30 and disconnecting the generator 20 from the prime mover 10, and is composed of a resistive element in this embodiment. The resistive element constituting the protective load 42 may be a single resistive element or a group of resistive elements connected in series or parallel.

The second circuit breaker 52 is a switch capable of interrupting the electrical continuity between the power converter 41 and the protected load 42. The second circuit breaker 52 is controlled to open and close by the control unit 43, and as described below, when it is determined that the generator 20 is not abnormal, it interrupts the electrical continuity between the power converter 41 and the protected load 42.

As shown in FIG. 1, the control unit 43 has a signal generating circuit 431. The signal generating circuit 431 generates a control signal for controlling the power generated by the power converter 41.

(Steady-state operation control)
3 is a control block diagram showing an example of the configuration of the propulsion system 100, illustrating details of the signal generating circuit 431 during steady operation control when no abnormality occurs in the generator 20. As shown in FIG. 3, the signal generating circuit 431 has a current command value generator 44, a current controller 45, and a power controller 46.

The current command value generator 44 generates a q-axis current command value i _d * and a q-axis current command value i _q * based on the torque target value τ* of the generator 20 and a power control signal output from a power controller 46 .

The torque target value τ* changes from moment to moment depending on the state of the power load 50, such as the fan and pump mounted on the aircraft. Since the generator 20 side cannot control the speed, the power controller 46 resets a new torque target value calculated from the power measured on the load side and the generator speed to balance the power consumed by the power load 50 and the power generated by the generator 20 and suppress voltage fluctuations to the equipment. If necessary, the accuracy of the current command value may be improved by feeding back d-axis current, q-axis current, DC voltage, and speed information.

The current controller 45 generates a voltage control variable V _uvw * based on the q-axis current command value i _d * and the q-axis current command value i _q *, and supplies this as a control command to the power converter 41. The power converter 41 controls the generator 20 based on the input voltage control variable V _uvw *, and supplies the generated DC voltage Vdc to the power load 42.

The power controller 46 generates a power control signal to be fed back to the current command value generator 44, based on the output of the speed detector 33 that detects the rotation speed of the prime mover 10 and the power measurement value of the power load 50. The rotation speed of the prime mover 10 is controlled by the prime mover controller 15, based on the engine speed command ω _c * and the actual engine speed value ω _c detected by the speed detector 33.

(Protection and Control)
The control unit 43 further has a determination unit 432 that determines an abnormality in the generator 20 based on the output of the monitoring sensor 31. When the determination unit 432 determines that the generator 20 is abnormal, the control unit 43 executes protective control to apply to the mechanical fuse 30 a torsional vibration torque that breaks the mechanical fuse 30 by inputting a torque command value, the target torque value of which changes periodically, to the power converter 41 as a control command for generating a torsional vibration torque.

As an example, FIG. 4 shows the state when a layer short occurs in the electromagnetic coil C of the generator 20 wound in the same slot (same tooth part). The stator 22 has multiple slot parts divided by multiple teeth, and in this case, the state in which the short circuit shown by the thick solid line in the figure is formed by the electromagnetic coil of the same phase (for example, U phase) stored in one slot part shorting between different layers of turns. The magnetic flux by the field coil corresponds to the magnetic flux generated in the tooth part. If a rotor that constantly generates field magnetic flux such as a permanent magnet field type continues to rotate in this state, a short-circuit current will continue to flow in the short-circuited section that tries to cancel the magnetic flux generated by the rotor magnetic pole. At this time, localized heat is generated, and if this state is left unattended, there is a high risk of a fire, etc.

On the other hand, when applied to ships and aircraft, it is necessary to move to a safe location such as a port or airport using the minimum amount of power. To do this, it is necessary to disconnect the prime mover 10 and the generator 20 by cutting the mechanical fuse 30, stop the generator 20 to prevent a fire, and take evacuation action using the power of the prime mover 10.

To detect signs of a rare short, there is a method of detecting anomalies by trend management of the non-uniformity of temperatures of temperature measuring elements embedded in an evenly spaced arrangement in the stator 22 of the generator 20. For example, if a failure occurs near temperature measuring element 31a as shown in Figure 2, the detected temperatures T1 of temperature measuring element 31a, T2 of temperature measuring element 31b, and T3 of temperature measuring element 31c are normally uniform, but it is expected that a gradient will occur in the detected temperatures, for example, T1>T2>T3, and anomalies are detected using a threshold value obtained from experience.

Similarly, if a bearing abnormality occurs and it is necessary to stop the rotating electric machine, the abnormality can be detected by trend management of the temperatures of the direct drive side and the non-direct drive side. In this embodiment, the determination unit 432 detects an abnormality in the generator 20 at the timing when such an abnormality is detected, and issues an instruction to disconnect the prime mover 10 and the generator 20.

In the existing method, it was necessary to generate a transiently large torque to cut the mechanical fuse 30. In order to intentionally generate a transient excessive torque, the capacity of the inverter that constitutes the power converter 41 must be made large, but this has the drawback of making the device larger.

On the other hand, in this embodiment, at any timing when an abnormality is detected, the first circuit breaker 51 is first opened to disconnect the generator 20 from the power load 50. After this, the second circuit breaker 52 is closed to switch the load from the power load 50 to the protected load 42. The control unit 43 generates a vibration torque by controlling the power consumed by the protected load 42. Since the generator does not completely lose its function when a layer short occurs, it is possible to control the load.

ただし、Ｖ_a：各相電圧、Ｅ₀：誘起電圧、ｘ_s：同期リアクタンス、δ：負荷角、ω：電源周波数、ｐ：極対数である。 In general, in a permanent magnet generator (PMSG), the rated power P and torque τ are expressed by the following equations (1) and (2), respectively.

where V _a is each phase voltage, E ₀ is induced voltage, x _s is synchronous reactance, δ is load angle, ω is power supply frequency, and p is the number of pole pairs.

ただし、ｋ：定数、ω_s：振動周波数、δ_s：任意の負荷角である。 If the voltage amplitude applied by power converter 41 is Va=Va{1−k+k sin(ω _s t)}, then power P _s and torque τ _s are expressed by the following equations.

where k is a constant, ω _s is a vibration frequency, and δ _s is an arbitrary load angle.

Focusing on the sin _ωs term in equation (3), it can be seen that the rated torque can be excited at a frequency of _ωs with an amplitude of ( _ksinδs /sinδ) times. By arbitrarily adjusting each parameter in the power conversion device, it is possible to generate torque vibration with a desired amplitude.

(Principle of torque vibration generation)
During steady operation (see FIG. 3), ω, which depends on the rotation speed in equation (2), is constant because there is no change in the prime mover speed, which depends on the rotation speed of the propeller (thruster 12), and under this condition, the induced voltage E ₀ is also constant. Therefore, the power load expressed in equation (1) is adjusted by changing the product (V _a sin δ) of each phase voltage and the load angle. In terms of control, as described later, the generator torque τ expressed in equation (2) is generated by controlling the d-axis current i _d and the q-axis current i _q . This is equivalent to adjusting each phase voltage and the load angle.

5 is an equivalent circuit diagram of a permanent magnet generator (PMSG), where A indicates the d-axis current circuit and B indicates the q-axis current circuit. The generator torque is expressed as follows, using ψ _a as the magnetic flux of the permanent magnet, i _od and i _oq as the d-axis and q-axis currents that contribute to the torque (since the current due to iron loss is generally small, i _od ≈ d-axis current i _d , i _oq ≈ q-axis current i _q ), and L _d and L _q as the d-axis and q-axis inductances, respectively:

At this time, the current command values i _od *, i _oq * for the torque command value τ _pre * are set as follows, with K being a constant:

Figure 6 is a control block diagram of the propulsion system 100 showing details of the signal generating circuit 431 during protective control when an abnormality is detected in the generator 20. When the protective device 40 executes protective control as shown in Figure 5, the protective load 42 is connected to the power converter 41 instead of the power load 50 by switching the first circuit breaker 51 and the second circuit breaker 52.

Before the start of protective control, the torque command value was controlled according to the state of the power load 50, but when protective control is executed, the torque is oscillated to resonate with the torsional frequency _ωts of the weak point (mechanical fuse 30), so that an arbitrary torque is specified on the control side. In other words, the power generated by the generator 20 is consumed by the protected load 42, but since it does not need to be connected to equipment that requires a guarantee of power quality, an arbitrary load may be generated without speed feedback to the torque target value.

ただし、ｋは定数（０＜ｋ＜１）、ｔは時間、τ_aveは振動トルクの平均値であり、振動振幅に相当する。 The torque can be changed with time t to generate a vibration torque, and the equation is, for example, as follows:

where k is a constant (0<k<1), t is time, and τ _ave is the average value of the vibration torque, which corresponds to the vibration amplitude.

At this time, the current command values i _od *, i _oq * are set as follows, with K being a constant.

Incidentally, since the fuel of the prime mover 10 is controlled to maintain the current operation, the rotation speed does not change (ω _e = constant). Even if the speed were to change, it would not have a significant effect because the frequency of the torque fluctuation is what is important. As described above, unlike the case of the power load 50 (during steady operation), the protected load 42 only needs to consume a specified amount of power, so feedback of the power consumption of the protected load 42 is not necessary.

(Power oscillation)
The protection device 40 oscillates the torque as described above, thereby applying power oscillation (torsional oscillation torque) to the mechanical fuse 30. An example waveform of the power oscillation is shown in FIG.

In vibration torque resonance, the GD2 (flywheel effect) of the generator 20 is usually small relative to the load, so when torsional resonance occurs in a mode different from that of the propeller 12, prime mover 10, and shaft (mechanical fuse 30) in which only the phase of the generator 20 is different, as shown in Figure 8, the resonance torque becomes maximum.

Figure 9 shows the frequency and response magnification of the vibration torque. When the frequency of the vibration torque is gradually increased, the response magnification is approximately 1 when the frequency is low, but it can be seen that the torque can be increased by resonance by matching the vibration frequency as closely as possible to the resonance frequency _f0 . Note that the torque can be amplified by several tens of times depending on the adjustment of the frequency.

By utilizing this phenomenon, it is preferable to match the frequency of the vibration torque when protective control is executed to the resonance frequency _f0 . As a result, the response torque acting on the mechanical fuse 30 is greatly amplified relative to the torque of the generator 20, as shown in Fig. 10. Since the magnitude of the vibration torque can be amplified up to about 10 times the rated value, this can be utilized to repeatedly generate a large torque to cut the mechanical fuse 30 without increasing the power supply capacity. As for the resistor constituting the protective load 42, it is only necessary to have a short-term capacity to generate the vibration torque, so that the device can be prevented from becoming large, and it is expected to be particularly effective in mobility applications.

As described above, according to this embodiment, when an abnormality in the generator 20 is detected, a torsional vibration torque is applied to the mechanical fuse 30, so that the generator 20 showing signs of failure can be mechanically disconnected at any time while the prime mover 10 continues to operate.

In addition, according to this embodiment, a control command that generates a torsional vibration torque is input to the power converter 41, with the torque command value having a periodically changing target torque value, so that a vibration torque sufficient to cut the mechanical fuse 30 can be generated without generating a transiently large torque.

Furthermore, since the vibration torque can be generated by the power converter 41 used during steady-state operation control, it is not necessary to have a large capacity inverter that constitutes the power converter 41, and therefore it is possible to prevent the device from becoming too large.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment and can of course be modified in various ways.

For example, in the above embodiment, a layer short circuit was given as an example of the cause of the accident, but even if a ground fault occurs in a winding or between two independent windings, the above-mentioned effects can be obtained by using similar control depending on the severity of the accident.

In addition, in the above embodiment, the protective load 42 is used to generate the vibration torque required to break the mechanical fuse 30, but this is not limited to this, and the vibration torque may be generated using the power load 50. In this case, the installation of the protective load 42, the first circuit breaker 51, and the second circuit breaker 52 can be omitted.

In the above embodiment, the AC power generated by the generator 20 is converted to DC power by the power converter 41 and supplied to the power load 50, but this is not limited to the above. An AC (Alternating Current) converter may be provided between the power converter 41 and the power load 50 to connect an AC load as the power load.

Furthermore, in the above embodiment, the rotating electric machine is a permanent magnet synchronous type generator 20, but this is not limited thereto, and an AC motor may be used as the rotating electric machine. As an example, FIG. 11 shows a parallel hybrid type propulsion system 200. This propulsion system 200 includes a motor 60 having a rotor connected to the prime mover 10, and a battery 61 that is a power source for driving the motor 60, and is configured so that the motor 60 connected to the battery 61 can assist part of the shaft power of the prime mover 10.

In FIG. 11, the power converter 41 converts the DC power of the battery 61 into AC power and outputs it to the motor 60 based on instructions from the control unit 43. When the control unit 43 detects an abnormality in the motor 60, it closes the second circuit breaker 52 to connect the power converter 51 to the protective load 42, and generates a torsional vibration torque that breaks the mechanical fuse 30, thereby disconnecting the motor 60 from the prime mover 10. This makes it possible to obtain the same effects as the above-mentioned embodiment.

10... prime mover 20... generator (rotating electric machine)
30... Mechanical fuse 31... Monitoring sensor 40... Protection device 41... Power converter 42... Protected load 43... Control unit 50... Power load 51... First circuit breaker 52... Second circuit breaker 60... Motor (rotating electric machine)
100, 200...Propulsion system

Claims (12)

The prime mover,
a permanent magnet field type rotating electric machine having a rotor connected to the prime mover;
a mechanical fuse connected between the prime mover and the rotating electric machine;
A sensor for monitoring a state of the rotating electric machine;
a protection device configured to be able to apply a torsional vibration torque to the mechanical fuse to break the mechanical fuse based on an output of the sensor. 2. The propulsion system of claim 1,
The protection device comprises:
a power converter connected to the rotating electric machine;
a protection load that consumes power generated by the power converter;
a control unit that determines whether or not there is an abnormality in the rotating electric machine based on an output of the sensor, and inputs a control command to the power converter to generate the torsional vibration torque when it is determined that there is an abnormality in the rotating electric machine. 3. The propulsion system of claim 2,
The control command includes a torque command value whose target torque value changes periodically. 4. The propulsion system of claim 3,
The control unit generates a torque command value that generates a torsional vibration torque having a frequency equivalent to a torsional resonance frequency of the mechanical fuse. 3. The propulsion system of claim 2,
The protection device further includes a first circuit breaker capable of interrupting conduction between the power converter and an electric power load that operates by receiving electric power generated by the power converter,
When the control unit determines that the rotating electric machine has an abnormality, the control unit causes the first circuit breaker to cut off electrical continuity between the power converter and the power load. 6. The propulsion system of claim 5,
The protection device further includes a second circuit breaker capable of interrupting conduction between the power converter and the protected load,
When the control unit determines that the rotating electric machine is not abnormal, the control unit causes the second circuit breaker to cut off electrical continuity between the power converter and the protected load. A propulsion system according to any one of claims 1 to 6,
The rotating electric machine is a generator. A propulsion system according to any one of claims 1 to 6,
The rotating electric machine is a motor. A propulsion system according to any one of claims 1 to 6,
The mechanical fuse is tubular in shape. A propulsion system according to any one of claims 1 to 6,
The sensor is a temperature sensor that measures a temperature of the rotating electric machine, or a current sensor that detects a current flowing through the rotating electric machine. A propulsion system according to any one of claims 1 to 6,
The prime mover is a jet engine. A protection device for a rotating electric machine including a prime mover, a permanent magnet field type rotating electric machine having a rotor connected to the prime mover, and a mechanical fuse connected between the prime mover and the rotating electric machine,
a power converter connected to the rotating electric machine;
a protection load that consumes power generated by the power converter;
a control unit that determines whether or not there is an abnormality in the rotating electric machine based on an output of a sensor that monitors the state of the rotating electric machine, and when it is determined that there is an abnormality in the rotating electric machine, inputs a control command to the power converter to generate a torsional vibration torque that will break the mechanical fuse.

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