Controller for starting system and control method for starting system

Abstract

To provide a controller and control method for a starting system that can properly perform starting control of a rotary machine using a sensorless controlled synchronous motor without the need for an additional sensor.SOLUTION: The controller of a starting system includes a synchronous motor that is mechanically connected to a rotary machine and starts the rotary machine, a drive circuit that is electrically connected to the synchronous motor and drives the synchronous motor, and a control circuit. The synchronous motor is controlled by a sensorless control, in which the rotary angle is not detected. The processing circuit generates a first drive signal that causes a first direct current to flow for a predetermined first period, thereby generating a magnetic field in a stator of the synchronous motor in a first reference angle direction at the start of rotation of the rotary machine, and outputs it to the drive circuit.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a controller for a starting system and a method for controlling a starting system. [Background technology]

[0002] There is known a starting system that starts an engine, which is a driving source in a vehicle, ship, aircraft, etc., by a synchronous motor. It is possible to control the synchronous motor for starting such an engine by sensorless control, in which the rotation angle is not detected by a rotation angle sensor. By using sensorless control, it is possible to reduce the size of the system and the risk of failure. The following Patent Document 1 describes the placement of a sensor that detects the rotation of the rotor on the non-rotating side of the bearing of a rotating electric machine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-186017 Summary of the Invention [Problem to be solved by the invention]

[0004] In a sensorlessly controlled synchronous motor, the angular speed and phase of the synchronous motor can be estimated using the current flowing through the synchronous motor. However, when the synchronous motor is used to start a rotating machine such as an engine, the rotation speed of the synchronous motor is 0, and therefore the induced voltage of the synchronous motor is 0, making it difficult to estimate the angular speed ω and phase θ of the synchronous motor 3.

[0005] If a sensor that detects the rotation of the rotor is installed as in Patent Document 1, the rotation position can be detected, but the advantage of sensorless control is diminished. In other words, it leads to an increase in the size of the system and an increase in the risk of failure. In addition, the increase in the number of parts also increases the cost.

[0006] The present disclosure is devised to solve the above-mentioned problems, and aims to provide a starting system controller and a starting system control method that can appropriately perform starting control of a rotating machine that uses a sensorlessly controlled synchronous motor without adding any additional sensors. [Means for solving the problem]

[0007] A controller of a starting system according to one embodiment of the present disclosure is a controller of a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, the controller including a processing circuit, the synchronous motor being controlled by sensorless control in which detection of a rotation angle is not performed, and the processing circuit generating a first drive signal at the start of startup of the rotating machine such that a first DC current that generates a magnetic field in a first reference angle direction is passed through a stator of the synchronous motor for a predetermined first period of time, and outputting the first drive signal to the drive circuit.

[0008] A controller of a starting system according to another aspect of the present disclosure is a controller of a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, the controller including a processing circuit, the synchronous motor being controlled by sensorless control in which detection of a rotation angle is not performed, and the processing circuit generating a start-up drive signal at the start of startup of the rotating machine such that a start-up AC current of a predetermined startup frequency and a predetermined current target value flows for a predetermined period of time, and outputs the signal to the drive circuit.

[0009] A controller of a starting system according to another aspect of the present disclosure is a controller of a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, the controller further including a processing circuit, the synchronous motor being controlled by sensorless control in which detection of a rotation angle is not performed, the processing circuit generating a first drive signal at the start of startup of the rotating machine such that a first DC current that generates a magnetic field in a first reference angle direction is passed through a stator of the synchronous motor for a predetermined first period, and outputting the first drive signal to the drive circuit, and after passing the first DC current for the predetermined period, generating a second drive signal such that a second DC current that generates a magnetic field in a second reference angle direction that is a predetermined angle interval ahead of the first reference angle is passed through the stator of the synchronous motor for a predetermined second period, and outputting the second drive signal to the drive circuit.

[0010] A controller of a starting system according to another aspect of the present disclosure is a controller of a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, the controller including a processing circuit, the synchronous motor being controlled by sensorless control in which detection of a rotation angle is not performed, and the processing circuit generating a start-up drive signal at the start of startup of the rotating machine such that a start-up AC current of a predetermined startup frequency and a predetermined current target value flows for a predetermined period of time, and outputs the signal to the drive circuit.

[0011] A control method for a starting system according to another aspect of the present disclosure is a control method for a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, wherein the synchronous motor is controlled by sensorless control in which no detection of the rotation angle is performed, and at the start of starting the rotating machine, a first drive signal is generated to flow a first DC current for a predetermined first period of time such that a magnetic field in a first reference angle direction is generated in the stator of the synchronous motor, and the first drive signal is output to the drive circuit.

[0012] A control method for a starting system according to another aspect of the present disclosure is a control method for a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, wherein the synchronous motor is controlled by sensorless control in which no detection of a rotation angle is performed, and at the start of starting the rotating machine, a first drive signal is generated such that a first DC current is passed through a stator of the synchronous motor for a predetermined first period of time, such that a magnetic field in a first reference angle direction is generated in the stator of the synchronous motor, and the first drive signal is output to the drive circuit, and after the first DC current is passed through the stator of the synchronous motor for the first period of time, a second drive signal is generated such that a second DC current is passed through a stator of the synchronous motor for a predetermined second period of time, such that a magnetic field in a second reference angle direction that is a predetermined angle interval ahead of the first reference angle is generated in the stator of the synchronous motor, and the second drive signal is output to the drive circuit.

[0013] A control method for a starting system according to another aspect of the present disclosure is a control method for a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, wherein the synchronous motor is controlled by sensorless control in which detection of a rotation angle is not performed, and at the start of startup of the rotating machine, a start-up drive signal is generated such that a start-up AC current of a predetermined startup frequency and a predetermined current target value flows for a predetermined period of time, and is output to the drive circuit. Effect of the Invention

[0014] According to the present disclosure, startup control of a rotating machine using a sensorless-controlled synchronous motor can be appropriately performed without adding any sensors. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a starting system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram illustrating an example of a circuit configuration of the first power converter illustrated in FIG. [Diagram 3] FIG. 3 is a diagram showing a schematic configuration of a processing circuit in the starting system shown in FIG. [Figure 4] FIG. 4 is an image diagram illustrating a control mode in the first embodiment. [Diagram 5] FIG. 5 is an image diagram illustrating a control mode in the second embodiment. [Figure 6] FIG. 6 is an image diagram illustrating a control mode in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following, elements having the same or similar functions are denoted by the same reference numerals throughout the drawings, and duplicated descriptions thereof will be omitted.

[0017] [Embodiment 1] Fig. 1 is a block diagram showing a schematic configuration of a starting system according to an embodiment of the present disclosure. As shown in Fig. 1, the starting system 1 according to the present embodiment includes an engine 2 and a synchronous motor 3. The engine 2 is configured as a driving source for a moving body such as a vehicle, a ship, or an aircraft. The engine 2 includes, for example, a gas turbine engine. Note that the engine 2 may be a reciprocating engine.

[0018] The synchronous motor 3 is mechanically connected to the engine 2. As a result, the synchronous motor 3 can rotate in synchronization with the rotation of the output shaft 4 of the engine 2. The synchronous motor 3 may be directly connected to the output shaft 4 of the engine 2, or may be connected to the output shaft 4 of the engine 2 via a power transmission mechanism such as a gear. The synchronous motor 3 is configured as a synchronous motor generator capable of generating electricity by using the driving force of the engine 2. In this embodiment, the synchronous motor 3 is controlled by sensorless control in which the rotation angle is not detected by a rotation angle sensor. The synchronous motor 3 has a cylindrical rotor to accommodate the high-speed rotation of the engine 2. That is, the synchronous motor 3 in this embodiment is a cylindrical synchronous motor in which magnets are arranged on the surface of the rotor. However, the synchronous motor 3 is not limited to this, and may have, for example, a salient pole rotor.

[0019] Furthermore, the starting system 1 includes a first power converter 5 electrically connected to the synchronous motor 3. The first power converter 5 is configured as a drive circuit that drives the synchronous motor 3. The first power converter 5 and the synchronous motor 3 are connected by an AC wiring 6. The first power converter 5 is connected to a predetermined power source 8 via a second power converter 7. The first power converter 5 and the second power converter 7 are connected by a DC wiring 9. A capacitor 10 that defines a DC voltage in the DC wiring 9 is electrically connected to the DC wiring 9. The first power converter 5 converts the AC power generated by the synchronous motor 3 into DC power and supplies it to the DC wiring 9, and converts the DC power in the DC wiring 9 into AC power and supplies it to the synchronous motor 3.

[0020] The power source 8 may be, for example, an AC power source system such as an AC system in a vehicle, or may be, for example, a DC power source system such as a battery. That is, the power source wiring 11 between the second power converter 7 and the power source 8 is AC wiring when the power source 8 is an AC power source system, and is DC wiring when the power source 8 is a DC power source system. The second power converter 7 converts the DC power of the DC wiring 9 into power to be supplied to the power source 8, and converts the power source power from the power source 8 into DC power to be supplied to the DC wiring 9. The second power converter 7 is an AC-DC converter when the power source 8 is an AC power source system, and is a DC-DC converter when the power source 8 is a DC power source system.

[0021] Furthermore, the starting system 1 includes a controller 12. The controller 12 controls the first power converter 5 and the second power converter 7. The controller 12 includes a processing circuit 13 that performs various signal processing. The processing circuit 13 includes a computer such as a microcontroller, a personal computer, or a PLC (Programmable Logic Controller). For example, the processing circuit 13 includes a processor, a memory, and peripheral circuits. Moreover, the processing circuit 13 of the controller 12 may be configured by a plurality of divided processing circuits.

[0022] The processor includes, for example, a CPU or an MPU. The memory includes volatile memory such as a ROM, a RAM, and a register, and non-volatile memory such as a flash memory. The memory stores a control program for the power converters 5, 7 in advance. The memory includes peripheral circuits, an input / output interface, and the like. The processor, memory, and peripheral circuits transmit data to each other via a bus. The processor executes the control program to perform arithmetic processing (described later) based on various information stored in the memory.

[0023] It should be noted that the functions of the elements disclosed herein can be performed using circuits or processing circuits including general purpose processors, special purpose processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, or combinations thereof configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this specification, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed in this specification or other known hardware that is programmed or configured to perform the recited functions. In the case where the hardware is a processor that is considered a type of circuit, the circuit, unit, means, or part is a combination of hardware and software, and the software is used to configure the hardware or processor.

[0024] FIG. 2 is a diagram showing an example of a circuit configuration of the first power converter shown in FIG. 1. In the example of FIG. 2, the first power converter 5 is configured as a PWM (Pulse Width Modulation) inverter circuit. In this case, the first power converter 5 is realized by, for example, a three-phase bridge circuit. The first power converter 5 converts DC power provided by a DC wiring 9 into three-phase AC power and supplies it to the synchronous motor 3. That is, the AC wiring 6 includes three connection wirings 6a, 6b, and 6c. The connection wirings 6a, 6b, and 6c are connected to three terminals 3a, 3b, and 3c of the synchronous motor 3, respectively. The windings of the stator connected to the three terminals 3a, 3b, and 3c, respectively, correspond to the a-phase winding, the b-phase winding, and the c-phase winding.

[0025] The first power converter 5 includes a plurality of switching elements T for passing AC current through each of the connection wirings 6a and 6c. The switching elements T are switched between on and off states based on a drive signal Sd1 from the controller 12. In the switching elements T, the on state means a conductive state between the main terminals of the switching elements T, and the off state means a cut-off state between the main terminals of the switching elements T. The switching elements T are realized by, for example, transistors. For example, in the example of FIG. 2, the switching elements T are IGBTs or bipolar transistors. In this case, a diode D is connected in inverse parallel to the switching elements T. The switching elements T may be field-effect transistors such as MOSFETs. In this case, the diode D does not need to be connected to the switching elements.

[0026] In this embodiment, the switching element T includes six switching elements T1U, T1D, T2U, T2D, T3U, and T3D. The switching elements T1U and T1D are connected in series to form a switching element pair, and the switching element pair is connected in parallel to the capacitor 10. Similarly, the switching elements T2U and T2D are connected in series to form a switching element pair, and the switching element pair is connected in parallel to the capacitor 10. Similarly, the switching elements T3U and T3D are connected in series to form a switching element pair, and the switching element pair is connected in parallel to the capacitor 10.

[0027] A connection wire 6a is connected to an intermediate wire 51 between the switching elements T1U and T1D. A connection wire 6b is connected to an intermediate wire 52 between the switching elements T2U and T2D. A connection wire 6c is connected to an intermediate wire 53 between the switching elements T3U and T3D.

[0028] The processing circuit 13 of the controller 12 generates a gate signal corresponding to each switching element T. The gate signal is a PWM modulated, i.e., pulse width modulated, signal. A combination of the gate signals for the multiple switching elements T becomes the drive signal Sd1.

[0029] The processing circuit 13 is capable of executing a power generation control mode in which the synchronous motor 3 functions as a generator, and a start control mode in which the synchronous motor 3 functions as a starter for the engine 2.

[0030] In the power generation control mode, the processing circuit 13 controls the first power converter 5 to convert the AC power in the AC wiring 6 between the synchronous motor 3 and the first power converter 5 into DC power and output it to the DC wiring 9. In the power generation control mode, the processing circuit 13 estimates the angular speed and phase of the magnetic poles of the rotor of the synchronous motor 3 from the actual current flowing through the synchronous motor 3 and a target voltage value in the AC wiring 6. The processing circuit 13 generates a drive signal Sd1 for controlling the first power converter 5, which functions as a rectifier, to follow the estimated angular speed and phase.

[0031] In the start control mode, the processing circuit 13 converts the DC power of the DC wiring 9 into AC power and controls the first power converter 5 to supply the AC power to the synchronous motor 3 in order to start the engine 2 from a stopped state. In the start control mode, the processing circuit 13 generates a drive signal Sd1 for controlling the first power converter 5 so that AC currents having a sine waveform with a phase difference of 120 degrees flow through the connection wirings 6a, 6b, and 6c. The rotor of the synchronous motor 3 is driven to rotate by such AC currents flowing through the connection wirings 6a, 6b, and 6c. The processing circuit 13 can change the speed of the rotor of the synchronous motor 3 by adjusting the drive signal Sd1.

[0032] In this embodiment, the processing circuit 13 executes a first control, which is a sensorless vector control, when the angular velocity of the synchronous motor 3 is equal to or greater than a predetermined reference angular velocity, and executes a second control different from the first control while the angular velocity of the synchronous motor 3 is less than a first angular velocity reference value ωa from the start of the synchronous motor 3. For example, the first angular velocity reference value ωa can be set to an angular velocity corresponding to a rotation speed at which the engine 2 can operate autonomously.

[0033] For example, the second control may be V / f control using a current target value. In this case, the processing circuit 13 generates the current target value using a preset value or an arithmetic expression. The processing circuit 13 generates a voltage target value using, for example, a PID calculation so that the actual current matches the current target value. The processing circuit 13 may perform control such that the ratio of the output voltage to the frequency of the first power converter 5 is constant. In this case, the processing circuit 13 generates a voltage target value such that the frequency of the power output by the first power converter 5 becomes the frequency target value.

[0034] The starting system 1 includes a current detector 15 that detects an AC current in the AC wiring 6 in order to control the first power converter 5 by the first control using the processing circuit 13 of the controller 12. The current detector 15 includes a first detector 15a that detects a current Ia in the connecting wiring 6a and a second detector 15c that detects a current Ic in the connecting wiring 6c. The current Ib in the connecting wiring 6b can be calculated from the vector sum of the current Ia in the connecting wiring 6a and the current Ic in the connecting wiring 6c.

[0035] Fig. 3 is a diagram showing a schematic configuration of a processing circuit in the starting system shown in Fig. 1. The processing circuit 13 includes an estimation unit 21 and a signal generation unit 22 as control blocks. The estimation unit 21 estimates the angular velocity and phase of the magnetic poles in the rotor of the synchronous motor 3. To this end, the estimation unit 21 has a dq conversion circuit 23, a model application circuit 24, and an estimation circuit 25.

[0036] The dq conversion circuit 23 outputs a d-axis actual current Id and a q-axis actual current Iq from the instantaneous value of the current flowing through the AC wiring 6 detected by the current detectors 15a and 15c, using an estimated magnetic pole phase θm, which will be described later. The model application circuit 24 estimates the current flowing through the synchronous motor 3, using a model calculation formula that models the synchronous motor 3. The model calculation formula is stored in advance in the memory of the processing circuit 13.

[0037] The d-axis actual current Id and the q-axis actual current Iq are input to the model application circuit 24. Furthermore, the d-axis voltage target value Vod and the q-axis voltage target value Voq generated by a voltage target value generation circuit 26 described later are input to the model application circuit 24. Furthermore, the estimated induced voltage Em estimated by an estimation circuit 25 is input to the model application circuit 24. The model application circuit 24 outputs the d-axis estimated current Imd and the q-axis estimated current Imq by substituting these values ​​Id, iq, Vod, Voq, and Em into the model computational equation and solving the model computational equation.

[0038] The estimation circuit 25 estimates the estimated induced voltage Em, the estimated angular velocity ωm, and the estimated phase θm from the d-axis estimated deviation ΔId between the d-axis actual current Id and the d-axis estimated current Imd and the q-axis estimated deviation ΔIq between the q-axis actual current Iq and the q-axis estimated current Imq using a predetermined estimation algorithm. The d-axis estimated deviation ΔId is obtained by subtracting the d-axis estimated current Imd from the d-axis actual current Id. The q-axis estimated deviation ΔIq is obtained by subtracting the q-axis estimated current Imq from the q-axis actual current Iq.

[0039] As described above, the estimated induced voltage Em estimated by the estimation circuit 25 is substituted into the model calculation formula in the model application circuit 24. The estimated phase θm is used in the dq conversion circuit 23 and a drive signal generation circuit 27 described later.

[0040] The signal generating unit 22 generates a drive signal Sd1 for the first power converter 5. To this end, the signal generating unit 22 has a voltage target value generating circuit 26 and a drive signal generating circuit 27. The voltage target value generating circuit 26 generates voltage target values ​​Vod, Voq using the d-axis actual current Id, the q-axis actual current Iq, and the estimated angular velocity ωm estimated by the estimation circuit 25.

[0041] For example, the voltage target value generation circuit 26 generates an angular velocity deviation Δω, which is the deviation between the estimated angular velocity ωm and the angular velocity target value ωo. The angular velocity deviation Δω is obtained by subtracting the estimated angular velocity ωm from the angular velocity target value ωo. The voltage target value generation circuit 26 performs PID calculation on the angular velocity deviation Δω to calculate the q-axis current target value Ioq. The d-axis current target value Iod is set according to the torque target value or the rotation speed target value, etc.

[0042] The voltage target value generating circuit 26 generates a d-axis target deviation ΔIod between the d-axis current target value Iod and the d-axis actual current Id, and a q-axis target deviation ΔIoq between the q-axis current target value Ioq and the q-axis actual current Iq. The d-axis target deviation ΔIod is obtained by subtracting the d-axis actual current Id from the d-axis current target value Iod. The q-axis target deviation ΔIoq is obtained by subtracting the q-axis actual current Iq from the q-axis current target value Ioq. The voltage target value generating circuit 26 performs PID calculations on the d-axis target deviation ΔIod to calculate the d-axis voltage target value Vod, and performs PID calculations on the q-axis target deviation ΔIoq to calculate the q-axis voltage target value Voq.

[0043] The drive signal generation circuit 27 generates a drive signal Sd1 from the voltage target values ​​Vod, Voq and the estimated phase θm. The drive signal generation circuit 27 performs an inverse dq transformation on the voltage target values ​​Vod, Voq using the estimated magnetic pole phase θm to calculate three-phase voltage target values ​​voa, vob, and voc. Furthermore, the drive signal generation circuit 27 generates a drive signal Sd1 by pulse-width modulating the three-phase voltage target values ​​voa, vob, and voc based on a predetermined carrier frequency fc.

[0044] At the beginning of starting the engine 2, the induced voltage in the synchronous motor 3 is zero or very small, making it difficult to estimate the angular velocity ω and phase θ of the synchronous motor 3. For this reason, the engine 2 is started by the second control instead of the first control. At the start of the engine 2, the processing circuit 13 gradually increases the frequency target value or the current target value. Accordingly, the rotation speed of the engine 2 increases together with the synchronous motor 3. As a result, the synchronous motor 3 is controlled without estimating the angular velocity and induced voltage of the synchronous motor 3.

[0045] However, in such a second control, the angular velocity ω and phase θ of the synchronous motor 3 are not estimated, and therefore, the feedback in the second control alone cannot correctly detect whether the synchronous motor 3 is rotating normally. In particular, when the synchronous motor 3 has a cylindrical rotor, the rotation angle of the rotor when rotation is stopped cannot be estimated, making estimation even more difficult.

[0046] In the conventional configuration, a rotating magnetic field is generated in the stator of the synchronous motor 3 by the three-phase AC currents Ia, Ib, and Ic output from the first power converter 5. The rotor of the synchronous motor 3 attempts to rotate so that its magnetic poles align with the generated rotating magnetic field, but there is a possibility that it cannot follow the rotation of the magnetic field, or that the inertial force of the rotor causes a large misalignment between the orientation of the rotor's magnetic poles and the orientation of the magnetic field generated in the stator. Once the orientation of the rotor's magnetic poles and the orientation of the magnetic field generated in the stator become significantly misaligned, there is a risk that the rotor will not be able to rotate.

[0047] Therefore, when starting the engine 2 and before executing the second control, the processing circuit 13 generates a first drive signal to flow a first DC current for a predetermined first period, which causes a magnetic field in a first reference angular direction to flow in the stator of the synchronous motor 3, and outputs the first drive signal to the first power converter 5. For example, when the first reference angular direction is a direction along the a-phase winding connected to the terminal 3a of the synchronous motor 3, the first drive signal is a switching signal for each switching element T such that the voltages applied to the terminals 3a, 3b, 3c of each phase are 1:-0.5:-0.5.

[0048] Fig. 4 is an image diagram illustrating a control mode in the embodiment 1. Fig. 4 shows the positional relationship between a rotor model 3r that typically shows the direction of the magnetic poles in the rotor of the synchronous motor 3, and a stator model 3s that typically shows the direction of the magnetic field generated in the stator of the synchronous motor 3.

[0049] State A1 in FIG. 4 shows a state immediately after the first DC current is passed when the synchronous motor 3 is stopped. In the example of FIG. 4, the first reference angular direction θ1 is the vertical direction in FIG. 4. In the stopped state, the orientation of the magnetic poles of the rotor does not necessarily match the first reference angular direction θ1. When the first DC current flows through the stator in this state, a magnetic field along the first reference angular direction θ1 is generated as shown in state A1 in FIG. 4. As a result, the rotor rotates so that the magnetic poles of the rotor are aligned with the magnetic field. As a result, the positional relationship between the rotor model 3r and the stator model 3s transitions from state A1 to state A2.

[0050] While the rotor rotates in this manner, the orientation of the magnetic field generated in the stator is maintained in the first reference angular direction θ1. Therefore, the orientation of the magnetic poles of the rotor coincides with the first reference angular direction θ1. In other words, the first period during which the first DC current flows is set to a period sufficient for the orientation of the magnetic poles of the rotor to coincide with the first reference angular direction θ1.

[0051] After the first period has elapsed, an AC current is supplied to the synchronous motor 3 by the second control. As a result, the direction of the magnetic field generated in the stator changes from the first reference angular direction θ1 to around the rotation axis of the synchronous motor 3, and the synchronous motor 3 starts to rotate. That is, the positional relationship between the rotor model 3r and the stator model 3s transitions from state A2 to state A3. In state A2, the direction of the magnetic field generated in the stator and the direction of the magnetic poles of the rotor match in the first reference angular direction θ1, so that the rotor can easily start to rotate around the rotation axis as the magnetic field generated in the stator rotates.

[0052] According to the above configuration, before an AC current is supplied to the stator of the synchronous motor 3, a first DC current that generates a magnetic field in the first reference angular direction θ1 is supplied for a predetermined first period. This makes it possible to align the direction of the magnetic field generated in the stator with the direction of the magnetic poles of the rotor before the magnetic field generated in the stator starts to rotate. As a result, it is possible to improve the tracking ability of the rotor when the magnetic field generated in the stator starts to rotate. Therefore, it is possible to appropriately perform start control of the engine 2 using the synchronous motor 3 that is sensorlessly controlled without adding a sensor.

[0053] Furthermore, by improving the rotor's tracking ability, it is possible to reduce the starting torque when supplying AC current to rotate the synchronous motor 3, and therefore the current supplied to the synchronous motor 3 can be reduced. In particular, when a gas turbine engine is used as the engine 2, the starting torque required to start the engine 2 may be significantly larger than when starting the synchronous motor 3 alone. In this case, the required current also becomes larger. According to the above configuration, such a large current can be reduced, which can greatly contribute to the miniaturization of the first power converter 5.

[0054] [Embodiment 2] Next, a second embodiment will be described. The structure of the starting system 1 is the same as that of the first embodiment. FIG. 5 is an image diagram for illustrating a control mode in the second embodiment. In this embodiment, as in the first embodiment, the processing circuit 13 generates a first drive signal for causing a first DC current to flow for a predetermined first period at the start of the engine 2, which generates a magnetic field in a first reference angular direction θ1 in the stator of the synchronous motor 3, and outputs the first drive signal to the first power converter 5. Furthermore, after causing the first DC current to flow for a predetermined period, the processing circuit 13 generates a second drive signal for causing a second DC current to flow for a predetermined period in the stator of the synchronous motor 3, which generates a magnetic field in a second reference angular direction θ2 that is advanced by a predetermined angle interval θin from the first reference angular direction θ1, and outputs the second drive signal to the first power converter 5.

[0055] State B1 in Fig. 5 is the same as state A1 in Fig. 4. When the first DC current flows through the stator, a magnetic field in a first reference angular direction θ1 is generated, and the rotor rotates so that the magnetic poles of the rotor are aligned with the magnetic field. However, depending on the magnitude of the first DC current and the original position of the magnetic poles of the rotor, as shown in state B2, the direction of the magnetic field generated in the stator during the first period when the first DC current flows may not be aligned with the direction of the magnetic poles of the rotor, or the motion of the rotor may become oscillatory.

[0056] Therefore, in this embodiment, the processing circuit 13 controls the first power converter 5 to flow a second DC current that generates a magnetic field in a second reference angular direction θ2 that is a predetermined angular interval θin ahead of the first reference angular direction θ1 in the stator of the synchronous motor 3 after the first DC current has flowed for a predetermined period. For example, in the example of FIG. 5, as shown in state B3, the angular interval θin is set to 30°. Therefore, the second reference angular direction θ2 is set to a direction inclined by 30° from the vertical direction in FIG. 5. The second period in which the second DC current is flowed may be the same period as the first period in which the first DC current is flowed, or may be different periods from each other.

[0057] When the second DC current flows through the stator, a magnetic field is generated along the second reference angular direction θ2, as shown in state B3. This causes the rotor to rotate so that the magnetic poles of the rotor are aligned with the magnetic field. As a result, the positional relationship between the rotor model 3r and the stator model 3s transitions from state B3 to state B4.

[0058] During such rotation of the rotor, the orientation of the magnetic field generated in the stator is maintained in the second reference angular direction θ2, so that the orientation of the magnetic poles of the rotor coincides with the second reference angular direction θ2.

[0059] After the second period has elapsed, an AC current is supplied to the synchronous motor 3 by the second control. As a result, the direction of the magnetic field generated in the stator changes from the second reference angular direction θ2 to around the rotation axis of the synchronous motor 3, and the synchronous motor 3 starts to rotate. That is, the positional relationship between the rotor model 3r and the stator model 3s transitions from state B4 to state B5. In state B4, the direction of the magnetic field generated in the stator and the direction of the magnetic poles of the rotor match in the second reference angular direction θ2, so that the rotor can easily start rotating around the rotation axis as the magnetic field generated in the stator rotates.

[0060] According to the above configuration, before supplying an AC current to the stator of the synchronous motor 3, a first DC current that generates a magnetic field in a first reference angular direction θ1 is supplied for a predetermined first period, and then a first DC current that generates a magnetic field in a second reference angular direction θ2 that is advanced by an angle interval θin from the first reference angular direction θ1 is supplied for a predetermined second period. By changing the angle of the stator to generate magnetic fields in multiple directions, it is possible to easily match the direction of the magnetic poles of the rotor with the direction of the magnetic field generated in the stator while a non-rotating magnetic field is generated. This makes it possible to improve the tracking ability of the rotor when the magnetic field generated in the stator starts to rotate. Therefore, it is possible to appropriately perform start control of the engine 2 using the sensorless-controlled synchronous motor 3 without adding a sensor.

[0061] Furthermore, in this embodiment, it is easier to match the direction of the magnetic poles of the rotor with the direction of the magnetic field generated in the stator even with a smaller DC current than in embodiment 1. Therefore, the magnitude of the DC current supplied to the stator can be made smaller than in embodiment 1. Also, the period during which a DC current is passed to generate a magnetic field in one reference angle direction can be made shorter than in embodiment 1.

[0062] In the present embodiment, the magnetic field generated in the stator changes in two directions, the first reference angular direction θ1 and the second reference angular direction θ2, in sequence, but the present invention is not limited to this. That is, the processing circuit 13 may generate a drive signal that sequentially changes the DC current flowing through the stator so that the magnetic field generated in the stator changes in three or more reference angular directions in sequence.

[0063] For example, the number of times the direction of the magnetic field is changed may be the number of times the direction of the magnetic field generated in the stator makes one revolution. For example, when the angular interval θin is 30°, the number of times the direction of the magnetic field is changed may be 12 times. Also, when the angular interval θin is 60°, the number of times the direction of the magnetic field is changed may be 6 times. By supplying a direct current that changes the direction of the magnetic field generated in the stator at every angular interval θin, the direction of the magnetic field generated in the stator is made to make one revolution around the rotation axis of the synchronous motor 3, and during that time, the possibility that the direction of the magnetic poles of the rotor coincides with the direction of the magnetic field generated in the stator can be increased.

[0064] However, the number of times the direction of the magnetic field is changed may be a number that causes the direction of the magnetic field generated in the stator to change more than one revolution, or may be a number that causes the direction of the magnetic field to change less than one revolution.

[0065] The DC current Is is determined by the torque to be generated, i.e., the starting torque Ts and the angular interval θin. If the torque constant is Kt, the DC current Is is expressed by the following formula. Is = Ts / (Kt cos θ in)

[0066] Therefore, the smaller the angle interval θin, the smaller the magnitude of the direct current. For example, it is preferable that the angle interval θin is greater than 0 and equal to or less than 60°.

[0067] [Embodiment 3] Next, a third embodiment will be described. The structure of the starting system 1 is similar to that of the first embodiment. FIG. 6 is an image diagram illustrating a control mode in the third embodiment. In this embodiment, the processing circuit 13 generates a start-time drive signal at the start of starting the engine 2 so as to flow a start-time AC current of a predetermined start frequency and a predetermined current target value for a predetermined period of time, and outputs the signal to the first power converter 5.

[0068] This embodiment can be considered as an embodiment in which the second embodiment is performed more continuously, that is, with a smaller angular resolution. In response to a start-up drive signal output from the processing circuit 13, the first power converter 5 supplies a start-up AC current to the AC wiring 6 for a predetermined period of time based on a constant start-up frequency and a constant current target value.

[0069] The starting frequency is set to be equal to or lower than the initial frequency value in the second control executed after a predetermined period of time has elapsed. In the second control, the processing circuit 13 sets the frequency target value so as to gradually increase from the initial frequency value. By setting the frequency to a low value in this way, the rotation of the magnetic field generated in the stator can be made slow and constant, and the orientation of the magnetic poles of the rotor can be made to more easily match the orientation of the magnetic field generated in the stator.

[0070] State C1 in Fig. 6 shows the state immediately after AC current is applied at the start of starting the synchronous motor 3 when the motor is stopped. At this time, a magnetic field is generated in a certain direction in the stator, similar to state A1 in Fig. 4. This causes the rotor to rotate so that the magnetic poles of the rotor are aligned with the magnetic field. As a result, the positional relationship between the rotor model 3r and the stator model 3s transitions from state C1 to state C2.

[0071] Unlike the first and second embodiments, an AC current flows through the stator, and the direction of the magnetic field generated in the stator changes. However, unlike typical startup control, the frequency of the AC current is fixed, and the speed at which the direction of the magnetic field generated in the stator changes around the rotation axis is constant. Therefore, by continuing the change in the direction of the magnetic field to a certain extent, the direction of the magnetic poles of the rotor tends to match the direction of the magnetic field generated in the stator.

[0072] This allows the direction of the magnetic field generated in the stator to be aligned with the direction of the magnetic poles of the rotor when the magnetic field generated in the stator starts to rotate. Therefore, the start-up control of the engine 2 using the synchronous motor 3 that is sensorlessly controlled can be appropriately performed without adding any sensors.

[0073] The predetermined period during which the AC current flows at the start of the motor is set to, for example, a period of about one electrical revolution. However, the predetermined period is not limited to this, and may be a period of less than one electrical revolution, or may be a period of more than one electrical revolution. The electrical angle φe is expressed as φe=φm / p, where φm is the mechanical angle indicating the rotation angle around the rotation axis of the rotor, and p is the number of pole pairs of the synchronous motor 3.

[0074] Furthermore, when current control is performed as the second control, the initial value of the current target value in the second control can be set to a current target value smaller than the AC current at the start of the motor. According to this embodiment, since the rotor has already started to rotate before the start of the second control, the magnetic flux rotates at a constant low frequency. This allows the rotor to be supplied with magnetic flux for a long period of time near the angle at which the maximum torque is generated, making starting torque unnecessary in the second control. Therefore, the AC current at the start of the motor can be set to a smaller current than when the second control is started without flowing the AC current at the start of the motor.

[0075] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various improvements, changes, and modifications are possible without departing from the spirit and scope of the present disclosure.

[0076] [Other embodiments] For example, in the above embodiment, the synchronous motor 3 is a synchronous motor generator capable of generating electricity using the rotational power of the engine 2, but the synchronous motor 3 does not have to function as a generator.

[0077] In the above embodiment, the engine 2 is exemplified as an object to be started by the power of the synchronous motor 3, but the present invention is not limited to this and can be applied to the case of starting other rotating machines. For example, other rotating machines may include various blowers such as an aeration blower, various fans, various pumps, etc.

[0078] [Summary of this disclosure] [Item 1] A controller of a starting system according to one embodiment of the present disclosure is a controller of a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, the controller including a processing circuit, the synchronous motor being controlled by sensorless control in which detection of a rotation angle is not performed, and the processing circuit generating a first drive signal at the start of startup of the rotating machine such that a first DC current that generates a magnetic field in a first reference angle direction is passed through a stator of the synchronous motor for a predetermined first period of time, and outputting the first drive signal to the drive circuit.

[0079] According to the above configuration, before an AC current is supplied to the stator of the synchronous motor, a first DC current that generates a magnetic field in a first reference angle direction is supplied for a predetermined first period. This makes it possible to align the direction of the magnetic field generated in the stator with the direction of the magnetic poles of the rotor before the magnetic field generated in the stator starts to rotate. As a result, it is possible to improve the tracking ability of the rotor when the magnetic field generated in the stator starts to rotate. Therefore, it is possible to appropriately perform start-up control of a rotating machine using a sensorless-controlled synchronous motor without adding a sensor.

[0080] [Item 2] A controller of a starting system according to another aspect of the present disclosure is a controller of a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, the controller further including a processing circuit, the synchronous motor being controlled by sensorless control in which detection of a rotation angle is not performed, the processing circuit generating a first drive signal at the start of startup of the rotating machine such that a first DC current that generates a magnetic field in a first reference angle direction is passed through a stator of the synchronous motor for a predetermined first period, and outputting the first drive signal to the drive circuit, and after passing the first DC current for the predetermined period, generating a second drive signal such that a second DC current that generates a magnetic field in a second reference angle direction that is a predetermined angle interval ahead of the first reference angle is passed through the stator of the synchronous motor for a predetermined second period, and outputting the second drive signal to the drive circuit.

[0081] According to the above configuration, before supplying an AC current to the stator of the synchronous motor, a first DC current that generates a magnetic field in a first reference angle direction is supplied for a predetermined first period, and then a first DC current that generates a magnetic field in a second reference angle direction that is an angle interval ahead of the second reference angle direction is supplied for a predetermined second period. By changing the angle of the stator to generate magnetic fields in multiple directions, it is possible to easily match the direction of the magnetic poles of the rotor with the direction of the magnetic field generated in the stator while a non-rotating magnetic field is generated. This makes it possible to improve the tracking ability of the rotor when the magnetic field generated in the stator starts to rotate. Therefore, it is possible to appropriately perform start-up control of a rotating machine using a sensorless-controlled synchronous motor 3 without adding a sensor.

[0082] [Item 3] A controller of a starting system according to another aspect of the present disclosure is a controller of a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, the controller including a processing circuit, the synchronous motor being controlled by sensorless control in which detection of a rotation angle is not performed, and the processing circuit generating a start-up drive signal at the start of startup of the rotating machine such that a start-up AC current of a predetermined startup frequency and a predetermined current target value flows for a predetermined period of time, and outputs the signal to the drive circuit.

[0083] According to the above configuration, at the start of starting the rotating machine, a start-up AC current having a predetermined start frequency and a predetermined current target value is supplied to the stator of the synchronous motor for a predetermined period of time. Since the frequency of the AC current is fixed, the speed at which the direction of the magnetic field generated in the stator changes around the rotation axis is constant. Therefore, the change in the direction of the magnetic field continues to a certain extent, so that the direction of the magnetic poles of the rotor tends to match the direction of the magnetic field generated in the stator. This makes it possible to align the direction of the magnetic field generated in the stator and the direction of the magnetic poles of the rotor when the magnetic field generated in the stator starts to rotate. Therefore, it is possible to appropriately perform start-up control of a rotating machine using a sensorless-controlled synchronous motor without adding a sensor.

[0084] [Item 4] In the controller of the starting system of item 3, the processing circuit may set a current target value smaller than the start-up AC current after flowing the start-up AC current for the predetermined period, generate a start-up control signal for controlling rotation of the synchronous motor based on the current target value, and output the start-up control signal to the drive circuit.

[0085] [Item 5] In the controller of the starting system of any one of items 1 to 4, the rotating machine may be an engine.

[0086] [Item 6] A control method for a starting system according to another aspect of the present disclosure is a control method for a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, wherein the synchronous motor is controlled by sensorless control in which no detection of the rotation angle is performed, and at the start of starting the rotating machine, a first drive signal is generated to flow a first DC current for a predetermined first period of time such that a magnetic field in a first reference angle direction is generated in the stator of the synchronous motor, and the first drive signal is output to the drive circuit.

[0087] [Item 7] A control method for a starting system according to another aspect of the present disclosure is a control method for a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, wherein the synchronous motor is controlled by sensorless control in which no detection of a rotation angle is performed, and at the start of starting the rotating machine, a first drive signal is generated such that a first DC current is passed through a stator of the synchronous motor for a predetermined first period of time, such that a magnetic field in a first reference angle direction is generated in the stator of the synchronous motor, and the first drive signal is output to the drive circuit, and after the first DC current is passed through the stator of the synchronous motor for the first period of time, a second drive signal is generated such that a second DC current is passed through a stator of the synchronous motor for a predetermined second period of time, such that a magnetic field in a second reference angle direction that is a predetermined angle interval ahead of the first reference angle is generated in the stator of the synchronous motor, and the second drive signal is output to the drive circuit.

[0088] [Item 8] A control method for a starting system according to another aspect of the present disclosure is a control method for a starting system including a synchronous motor mechanically connected to a rotating machine for starting the rotating machine, and a drive circuit electrically connected to the synchronous motor for driving the synchronous motor, wherein the synchronous motor is controlled by sensorless control in which detection of a rotation angle is not performed, and at the start of startup of the rotating machine, a start-up drive signal is generated such that a start-up AC current of a predetermined startup frequency and a predetermined current target value flows for a predetermined period of time, and is output to the drive circuit. [Explanation of symbols]

[0089] 1 Starting System 2. Engines (rotating machines) 3 Synchronous motor 5. First power converter (drive circuit) 12 Controller 13 Processing circuit

Claims

1. A controller for a starting system including a synchronous motor that is mechanically connected to a rotating machine and starts the rotating machine, and a drive circuit that is electrically connected to the synchronous motor and drives the synchronous motor, A processing circuit is provided, The synchronous motor is controlled by a sensorless control in which a rotation angle is not detected, The processing circuit generates a first drive signal that causes a first DC current to flow for a predetermined first period at the start of startup of the rotating machine, the first drive signal causing a magnetic field in a first reference angle direction to flow in the stator of the synchronous motor, and outputs the first drive signal to the drive circuit.

2. A controller for a starting system including a synchronous motor that is mechanically connected to a rotating machine and starts the rotating machine, and a drive circuit that is electrically connected to the synchronous motor and drives the synchronous motor, A processing circuit is provided, The synchronous motor is controlled by a sensorless control in which a rotation angle is not detected, The processing circuitry includes: a first drive signal is generated at the start of starting the rotating machine so as to cause a first DC current to flow for a predetermined first period in a stator of the synchronous motor, the first DC current generating a magnetic field in a first reference angle direction, and the first drive signal is output to the drive circuit; a second drive signal that causes a second DC current to flow for a predetermined second period after the first DC current has flowed for the first period, the second DC current generating a magnetic field in a second reference angle direction that is a predetermined angle interval ahead of the first reference angle, through the stator of the synchronous motor; and outputs the second drive signal to the drive circuit.

3. A controller for a starting system including a synchronous motor that is mechanically connected to a rotating machine and starts the rotating machine, and a drive circuit that is electrically connected to the synchronous motor and drives the synchronous motor, A processing circuit is provided, The synchronous motor is controlled by a sensorless control in which a rotation angle is not detected, The processing circuit generates a startup drive signal that causes a startup AC current of a predetermined startup frequency and a predetermined current target value to flow for a predetermined period at the start of startup of the rotating machine, and outputs the signal to the drive circuit.

4. 4. The controller of the starting system according to claim 3, wherein the processing circuit sets a current target value smaller than the start-up AC current after flowing the start-up AC current for the predetermined period, generates a start-up control signal for controlling rotation of the synchronous motor based on the current target value, and outputs the start-up control signal to the drive circuit.

5. 5. The controller of claim 1, wherein the rotating machine is an engine.

6. A control method for a starting system including a synchronous motor that is mechanically connected to a rotating machine and starts the rotating machine, and a drive circuit that is electrically connected to the synchronous motor and drives the synchronous motor, comprising: The synchronous motor is controlled by a sensorless control in which a rotation angle is not detected, A control method for a starting system, comprising: generating a first drive signal that causes a first DC current to flow for a predetermined first period at the start of starting the rotating machine, the first drive signal causing a magnetic field in a first reference angle direction to be generated in the stator of the synchronous motor; and outputting the first drive signal to the drive circuit.

7. A control method for a starting system including a synchronous motor that is mechanically connected to a rotating machine and starts the rotating machine, and a drive circuit that is electrically connected to the synchronous motor and drives the synchronous motor, comprising: The synchronous motor is controlled by a sensorless control in which a rotation angle is not detected, generating a first drive signal for causing a first DC current to flow for a predetermined first period at the start of startup of the rotating machine, the first drive signal causing a magnetic field in a first reference angle direction to be generated in a stator of the synchronous motor, and outputting the first drive signal to the drive circuit; a second drive signal for causing a second DC current to flow for a predetermined second period, the second DC current generating a magnetic field in a second reference angle direction that is a predetermined angle interval ahead of the first reference angle, through a stator of the synchronous motor, and outputting the second drive signal to the drive circuit.

8. A control method for a starting system including a synchronous motor that is mechanically connected to a rotating machine and starts the rotating machine, and a drive circuit that is electrically connected to the synchronous motor and drives the synchronous motor, comprising: The synchronous motor is controlled by a sensorless control in which a rotation angle is not detected, A control method for a starting system, comprising: generating a starting drive signal that causes a starting AC current of a predetermined starting frequency and a predetermined current target value to flow for a predetermined period at the start of starting the rotating machine; and outputting the signal to the drive circuit.

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