JP2017129065A - Vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a drive property while suppressing the use and generation of high voltage, without complicating a structure, in a vehicle.SOLUTION: A vehicle includes: an acceleration instructing portion; an engine which has a crank shaft; a driving member which drives the vehicle; a start generator; a battery; an inverter; and a control device which controls the inverter so as to make an engine output adjusting portion increase rotation power, and to make the start generator to drive the crank shaft with the power of the battery while carrying out slightly weak field control to the start generator, when the acceleration of the vehicle is instructed, and controls the inverter so as to make the engine output adjusting portion decrease the rotation power, and to make the start generator decrease the driving force of the crank shaft without applying voltage due to rotations of the crank shaft which is higher than the voltage of the battery from the start generator to a plurality of switching portions, when the acceleration instruction of the vehicle is stopped.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle.

For example, Patent Document 1 discloses an engine starter generator mounted on a vehicle or the like. The starting power generator of Patent Literature 1 includes a starting generator. The starter generator has an engine start function for starting the engine and a power generation function for generating electric power by rotating the engine. Moreover, in the starting power generator of patent document 1, a starting generator has an assist function which assists rotation of an engine by functioning as a motor during rotation of an engine.
An engine starter / generator as disclosed in Patent Document 1 is required to output a torque sufficient for starting the engine or assisting the engine, for example.
The starting power generation device of Patent Document 1 is provided with a battery and power storage means (battery or capacitor). The starting power generation device of Patent Document 1 switches the battery and the power storage means to a serial connection state when starting or assisting the engine. As a result, a high voltage is supplied to the starter generator. The starting power generator of Patent Document 1 increases the torque of the motor when the starting generator functions as a motor. In the starting power generator of Patent Document 1, when the starting generator is operated with the power generation function, a battery and power storage means are connected in parallel to the starting generator.

Japanese Patent Laying-Open No. 2015-68297

  In the configuration of Patent Document 1, the device for switching the connection state between the battery and the power storage means is complicated. Moreover, when switching the connection state of a battery and an electrical storage means, a high voltage may be inadvertently applied to other components in the vehicle (for example, a battery or a switching element in an inverter). In the starting power generator of Patent Document 1, it is necessary to change the connection state of each phase of the starting generator by a motor driver in order to suppress application of a high voltage when switching the connection state between the battery and the power storage means.

  A vehicle including a starter / generator that rotates a crankshaft of an engine with electric power from a battery includes a battery in addition to the engine. In such a vehicle, it is desirable that the weight and size of the battery do not affect the running performance of the vehicle as much as possible. Therefore, it is desirable to mount a battery that is as small and light as possible in the vehicle. Due to the restrictions on the size and weight of the battery, a battery having a relatively low voltage is usually used as the battery for driving the starter / generator. The voltage of such a battery is low compared with the voltage of a commercial power source, for example. In a vehicle equipped with a starter / generator that rotates the crankshaft of an engine with battery power, it is desired to drive the crankshaft of the engine with a large torque without supplying as high a voltage as possible to the starter / generator.

  In addition, in a vehicle including a starter / generator that rotates the crankshaft with the electric power of the battery, a target driven by the battery is a starter / generator that rotates the crankshaft. The crankshaft is heavy for a battery for driving the starter generator (ie, a battery having a relatively low voltage). A large amount of power is required to rotate the crankshaft. The power that must be output to the starter generator that rotates the crankshaft is compared to the power that a battery with a low voltage, such as a battery for driving the starter generator, outputs to a general drive target. large. In addition, there is a situation peculiar to a vehicle equipped with a starter / generator that rotates the crankshaft with electric power of the battery, in which the crankshaft is rotated by the combustion operation or inertia of the engine. For a vehicle equipped with a starter / generator that rotates the crankshaft with the electric power of the battery, the problem is how to control the rotation of the crankshaft, which is such a heavy object, with a battery having a relatively low voltage.

  An object of the present invention is to improve drivability while suppressing the use and generation of a high voltage without complicating the structure in a vehicle including a starter / generator that rotates a crankshaft of an engine with battery power. That is.

  The present invention employs the following configuration in order to solve the above-described problems.

(1) A vehicle,
The vehicle is
An acceleration instruction unit for instructing acceleration of the vehicle;
An engine configured to output rotational power generated by a combustion operation, the crankshaft outputting the rotational power to the outside of the engine, and an engine output adjusting unit configured to adjust the rotational power An engine having
A drive member that drives the vehicle by receiving rotational power output from the engine via the crankshaft;
A rotor connected to the crankshaft for rotation at a fixed speed ratio with respect to the crankshaft; the crankshaft is driven when the engine is started; and the engine is operated when the engine is combusted A starter generator, which is a three-phase brushless motor, driven by
A battery for transferring current to the starter generator;
An inverter that is disposed between the starter generator and the battery and includes a plurality of switching units that adjust a current flowing between the starter generator and the battery;
When acceleration of the vehicle is instructed by the acceleration instructing unit, the engine output adjusting unit increases rotational power and performs field weakening control on the starting generator with the power of the battery to the starting generator. When the inverter is controlled to drive a crankshaft and the acceleration instruction unit stops the vehicle acceleration instruction, the engine output adjustment unit reduces the rotational power, and the starter generator And a control device for controlling the inverter so as to reduce the driving force of the crankshaft to the starter generator without applying a voltage higher than the voltage of the battery due to the rotation of the crankshaft to the switching unit. .

  In the vehicle of (1), when the acceleration of the vehicle is instructed, the control device increases the rotational power to the engine output adjustment unit and performs the field weakening control on the starter generator with the electric power of the battery. The inverter is controlled to drive the crankshaft. For this reason, the starter / generator outputs a large torque at a higher rotational speed than when the field weakening control is not performed, for example. Therefore, the crankshaft is driven more strongly by the starter generator. As a result, the drivability of the vehicle including the starter / generator that rotates the crankshaft with the electric power of the battery is improved.

When the vehicle acceleration instruction is stopped, the driving force of the crankshaft by the starter generator and the rotational power of the engine are reduced. At this time, the rotation of the crankshaft does not stop immediately. For example, the engine may continue to rotate the crankshaft with reduced rotational power. In addition, the crankshaft may continue to rotate due to inertia. Therefore, the rotation of the crankshaft continues at least for a certain period after the vehicle acceleration instruction is stopped. When the crankshaft, which is heavy for the battery for driving the starter / generator when the control device controls the inverter, continuously rotates, an induced electromotive voltage generated in the starter / generator is applied to the switching unit. If the voltage applied to the switching unit is higher than the voltage of the battery, the inverter provided with the switching unit may not be able to properly control the current output from the starter generator. In a vehicle including a starter / generator that rotates the crankshaft with the electric power of the battery, the allowable current of the battery is low. For this reason, if the inverter cannot properly control the current, the current output to the battery may become excessively large for the battery.
In the configuration of (1), the control device reduces the driving force of the crankshaft to the starter generator without applying a voltage higher than the battery voltage due to the rotation of the crankshaft from the starter generator to the plurality of switching units. Therefore, the occurrence of a situation in which the induced electromotive voltage caused by the continuous rotation of the crankshaft affects the battery and the plurality of switching units can be suppressed. Moreover, since the control of the starter generator described above is realized by the inverter, the structure is not complicated.

  As described above, according to the configuration of (1), in the vehicle including the starter generator that rotates the crankshaft with the electric power of the battery, it is possible to drive while suppressing the use and generation of a high voltage without complicating the structure. Can be improved.

(2) The vehicle of (1),
When the acceleration instruction unit stops the acceleration instruction of the vehicle, the control device decreases the rotational power to the engine output adjustment unit and continues the field weakening control on the starter generator while continuing the field weakening control. The inverter is controlled so that a voltage caused by rotation of the crankshaft higher than the battery voltage is not applied from the starter generator to the plurality of switching units by reducing the driving force of the crankshaft.

  According to the configuration of (2), the starter generator decreases the driving force of the crankshaft while the field weakening control for the starter generator is continued. Therefore, the induced electromotive voltage is suppressed in the starter generator. Thereby, the occurrence of a situation where a voltage higher than the battery voltage is applied to the plurality of switching units is suppressed.

(3) The vehicle of (2)
At least in the case where acceleration of the vehicle is instructed by the acceleration instruction unit and in the case where the instruction of acceleration of the vehicle is stopped, the control device performs the field generation control while performing field weakening control on the starter generator. When the crankshaft is driven by the power of the battery in the machine, the starter / generator is set so that the maximum drive speed at which the crankshaft can be rotated is larger than the actual rotation speed of the crankshaft. On the other hand, field weakening control is performed.

  According to the configuration of (3), the field-weakening control is performed so that the generation of excessive voltage and current is suppressed with respect to the actual rotational speed of the crankshaft. For this reason, the situation where a voltage higher than the battery voltage is applied to the switching unit is further easily suppressed.

(4) The vehicle according to (2) or (3),
The control device weakens the field-weakening control in accordance with the decrease in the rotation speed of the crankshaft when the acceleration instruction unit stops the acceleration instruction of the vehicle.

  According to the configuration of (4), the field-weakening control is weakened as the rotational speed of the crankshaft decreases. Therefore, current consumption for field weakening control is suppressed, and a situation where a voltage higher than the battery voltage is applied to the plurality of switching units is easily suppressed.

(5) The vehicle of (1),
When the acceleration instruction unit stops the acceleration instruction of the vehicle, the control device reduces the rotational power to the engine output adjustment unit and short-circuits each phase of the starter generator. Further, the inverter is controlled such that a voltage resulting from rotation of the crankshaft higher than the battery voltage is not applied from the starter generator to the plurality of switching units by reducing the driving force of the crankshaft.

  According to the configuration of (5), the driving power of the crankshaft is reduced in the starter generator while short-circuiting each phase of the starter generator. Therefore, application of the induced electromotive voltage generated in the starter generator to the plurality of switching units is suppressed. Thereby, occurrence of a situation where a voltage higher than the battery voltage is applied from the starter generator to the plurality of switching units is suppressed. A short circuit of each phase of the starter generator contributes to a decrease in the rotational speed of the crankshaft, so that quick deceleration is possible.

(6) The vehicle according to any one of (1) to (5),
At least the maximum drive torque that allows the starter generator to drive the crankshaft with the power of the battery when the actual rotational speed of the crankshaft does not perform field weakening control on the starter generator, and When the rotational power of the engine is greater than the rotational speed of the crankshaft at which the torque for rotating the crankshaft is equal, the control device, when the acceleration instruction unit stops the acceleration instruction of the vehicle, The rotating power is reduced in the output adjustment unit, and the crankshaft of the crankshaft is applied to the starter generator so that a voltage caused by rotation of the crankshaft higher than the battery voltage is not applied to the plurality of switching units from the starter generator. Reduce driving force.

  According to the configuration of (6), when the acceleration instruction unit stops the vehicle acceleration instruction in a situation where a relatively high induced electromotive voltage is likely to be generated in the starter / generator, the control device sends the rotational power to the engine output adjustment unit. And the driving force of the crankshaft is reduced in the starting generator so that a voltage higher than the battery voltage is not applied to the plurality of switching units from the starting generator. In a situation where a relatively high induced electromotive voltage is likely to occur, occurrence of a situation where a voltage higher than the battery voltage is applied to the switching unit is suppressed.

(7) The vehicle according to any one of (1) to (6),
The starting generator is
A stator core having a plurality of teeth provided with slots in the circumferential direction and a winding wound around the teeth, all of the plurality of teeth having a portion around which the winding is wound. The stator,
And a rotor having a permanent magnet portion and a plurality of magnetic pole portions formed by the permanent magnet portion and provided on a surface facing the stator, the number of which is greater than the number of the plurality of teeth.

According to the structure of (7), a magnetic pole part is small compared with the structure which has the number of magnetic pole parts below the number of teeth, for example. For this reason, it is possible to increase the degree of field weakening at the magnetic pole portion by field weakening control using the magnetic field from the tooth around which the winding is wound.
Further, since the number of magnetic pole portions is larger than the number of teeth, the rotation speed based on the electrical angle of the starting generator is large. For this reason, an excessive current and voltage are largely suppressed by the field weakening control. Conversely, when maintaining the degree of current and voltage suppression, the winding resistance can be set low. For this reason, the torque by which the starter / generator drives the crankshaft can be increased.

  According to the present invention, in a vehicle equipped with a starter / generator that rotates a crankshaft of an engine with battery power, the drivability is improved while suppressing the use and generation of a high voltage without complicating the structure. be able to.

1 is an external view showing a vehicle according to an embodiment of the present invention. It is a fragmentary sectional view which shows typically the schematic structure of the engine unit shown in FIG. It is sectional drawing which shows a cross section perpendicular | vertical to the rotating shaft of the starting generator shown in FIG. It is a block diagram which shows the electrical schematic structure of the vehicle shown in FIG. It is a flowchart explaining operation | movement of a vehicle. (A) is explanatory drawing which shows typically the drive characteristic of a starter generator, (B) is explanatory drawing which shows typically a power generation characteristic. It is a block diagram explaining the outline | summary of vector control. (A) is explanatory drawing which shows typically the drive characteristic of the starter generator at the time of field weakening control, (B) is explanatory drawing which shows typically the power generation characteristic at the time of field weakening control. (A) is explanatory drawing which shows typically the drive characteristic of the starter generator when the instruction | indication of acceleration is stopped, (B) is typical about the electric power generation characteristic when the instruction | indication of acceleration is stopped. It is explanatory drawing shown. It is a flowchart explaining operation | movement of the vehicle which concerns on 2nd embodiment of this invention.

The inventor has studied a starter generator. The starter generator starts the engine and assists the engine. The starter generator is driven by the engine to generate power.
A starter generator, which is a three-phase brushless motor, generally outputs larger electric power as the rotational speed of the engine, that is, the rotational speed of the crankshaft becomes higher. For this reason, when the rotational speed of the engine is high while the vehicle is traveling, a large current is output from the starter generator. Current that exceeds the charging capacity of the battery does not contribute to charging. A current exceeding the charging capacity of the battery is one of the causes of the loss.
Therefore, the starter generator is desired to suppress the output current especially when the rotational speed is high.

  However, in the starter / generator, there is a trade-off relationship between the improvement in output torque when starting the engine and the suppression of the generated current after starting the engine. Therefore, if one of the torque improvement and the generation current suppression is prioritized, the other characteristic is degraded. For this reason, the starter generator has a problem that the output torque is reduced when the generated current is suppressed.

The starting power generator of Patent Document 1 supplies a high voltage to the starting generator by switching the battery and the power storage means to a serial connection state.
However, a circuit that switches the connection state of a power source that supplies power to the starter generator is more complicated and larger than a circuit that switches signal lines, for example.
Further, as described in Patent Document 1, when the connection of the battery and the power storage means to the starter / generator is simply switched from parallel connection to series connection, or switched from series connection to parallel connection, the following problems occur: Occurs. That is, there is a possibility that a high voltage is inadvertently applied to other components in the vehicle that are driven by power supplied from the battery or the power storage means.
The starting power generation device disclosed in Patent Literature 1 makes connection switching smooth by further complicating the control at the time of switching the connection state.

The inventor of the present invention relates to increasing the torque of a three-phase brushless motor without switching the connection state of a power source in a vehicle including a three-phase brushless motor as a starter generator that rotates an engine crankshaft with battery power. investigated. The present inventor has realized that, in a vehicle including a three-phase brushless motor that rotates the crankshaft of the engine with battery power, it is effective to increase the torque to weaken the three-phase brushless motor and perform field control. .
According to the field weakening control, the induced electromotive voltage can be suppressed by weakening the field. The induced electromotive voltage increases as the rotational speed of the three-phase brushless motor increases. By suppressing the induced electromotive voltage, the current supplied from the battery to the three-phase brushless motor increases, particularly in the region of a high rotational speed.
Therefore, it is possible to increase the torque of the starter generator, which is a three-phase brushless motor, without switching the connection state of the power source, particularly in the high rotational speed region.

However, the starter generator has a rotor connected to the crankshaft for rotation at a fixed speed ratio relative to the crankshaft. That is, the starter generator is connected to the engine without using a clutch or a variable transmission.
For this reason, even if the drive of the starter / generator is stopped by the control, the starter / generator is driven by the engine or rotates with inertia.
After the rotational power of the engine has decreased, the crankshaft rotation continues for at least a certain period. Therefore, even when the rotational power of the engine decreases, the starter generator is driven by the engine.
When the driving by the starter / generator is stopped by the control, the field increases when the field weakening control performed at the time of driving stops. When the starting generator is rotating, an induced electromotive voltage higher than the voltage of the battery may be applied to the switching unit due to the increased field. In this case, the inverter cannot properly control the current, and an excessive current flows through the battery.

In the vehicle having a starter / generator that rotates the crankshaft of the engine with the electric power of the battery, the inventor does not apply a voltage higher than the battery voltage to the switching unit when driving by the starter / generator is stopped by the control. By doing so, it was found that the situation where an excessive current flows through the battery can be suppressed.
The present invention has been completed based on the above-described findings.

  Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings.

[First embodiment]
FIG. 1 is an external view showing a vehicle according to an embodiment of the present invention.
A vehicle 1 shown in FIG. 1 is a vehicle with wheels. The vehicle 1 includes a vehicle body 2 and wheels 3a and 3b. Specifically, the vehicle 1 is a saddle type vehicle. The vehicle 1 is a motorcycle.
The vehicle 1 includes an engine unit EU. The engine unit EU includes an engine 10 and a starter generator 20 (see FIG. 2). That is, the vehicle 1 includes an engine 10 and a starter generator 20.
The rear wheel 3b receives the rotational power output from the engine 10 to drive the vehicle 1. The wheel 3b corresponds to an example of a drive member according to the present invention.

The vehicle 1 includes a main switch 5. The main switch 5 is a switch for supplying power to each part of the vehicle 1. The vehicle 1 includes a starter switch 6. The starter switch 6 is a switch for starting the engine 10. The vehicle 1 includes an accelerator operation element 8. The accelerator operation element 8 is an operation element for instructing acceleration of the vehicle 1. The accelerator operation element 8 is an example of an acceleration instruction unit.
The vehicle 1 includes a headlamp 7. The vehicle 1 includes a battery 4 that stores electric power. The vehicle 1 includes a control device 60 that controls each part of the vehicle 1.

  FIG. 2 is a partial cross-sectional view schematically showing a schematic configuration of the engine unit EU shown in FIG.

The engine 10 includes a crankcase 11, a cylinder 12, a piston 13, a connecting rod 14, and a crankshaft 15. The piston 13 is provided in the cylinder 12 so as to be reciprocally movable.
The crankshaft 15 is rotatably provided in the crankcase 11. The connecting rod 14 connects the piston 13 and the crankshaft 15. A cylinder head 16 is attached to the upper portion of the cylinder 12. A combustion chamber is formed by the cylinder 12, the cylinder head 16, and the piston 13. The crankshaft 15 is supported on the crankcase 11 via a pair of bearings 17 in a rotatable manner. A starter / generator 20 is attached to one end 15 a of the crankshaft 15. A continuously variable transmission CVT is attached to the other end 15 b of the crankshaft 15.

  The engine 10 is provided with a throttle valve SV and a fuel injection device 18. The throttle valve SV adjusts the amount of air supplied to the combustion chamber. The opening degree of the throttle valve SV is adjusted according to the operation of the accelerator operator 8 (see FIG. 1). The fuel injection device 18 supplies fuel to the combustion chamber by injecting fuel. The engine 10 is provided with a spark plug 19.

The engine 10 is an internal combustion engine. The engine 10 is supplied with fuel. The engine 10 outputs rotational power by a combustion operation for burning fuel. The rotational power is output to the outside of the engine 10 via the crankshaft 15.
The throttle valve SV adjusts the rotational power of the engine 10 by adjusting the amount of air supplied to the combustion chamber. The amount of air supplied to the combustion chamber is adjusted according to the opening of the throttle valve SV. The opening degree of the throttle valve SV is adjusted according to the operation of the accelerator operator 8 (see FIG. 1).
The fuel injection device 18 adjusts the rotational power output from the engine 10 by adjusting the amount of supplied fuel. The fuel injection device 18 is controlled by the control device 60. The control device 60 controls the fuel injection device 18 based on the detection result of a throttle sensor (not shown) that detects the opening of the throttle valve SV. The fuel injection device 18 is controlled to supply an amount of fuel based on the opening of the throttle valve SV.
That is, the fuel injection device 18 adjusts the rotational power output from the engine 10 in accordance with the instruction input to the accelerator operator 8. The fuel injection device 18 functions as a rotational power adjustment device that adjusts the rotational power output from the engine 10.
The engine 10 outputs rotational power via the crankshaft 15. The rotational power of the crankshaft 15 is transmitted to the wheel 3b via the continuously variable transmission CVT and a clutch (not shown). The vehicle 1 is driven by wheels 3 b that receive rotational power output from the engine 10 via the crankshaft 15.

  The engine 10 of this embodiment is a single-cylinder four-stroke engine. The engine 10 of this embodiment is an air-cooled engine. The engine 10 may be a water-cooled engine.

  The engine 10 has a high load region where the load for rotating the crankshaft 15 is large and a low load region where the load for rotating the crankshaft 15 is smaller than the load in the high load region during four strokes. Looking at the rotation angle of the crankshaft 15 as a reference, the low load region is wider than the high load region. More specifically, the engine 10 rotates forward while repeating four strokes of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. The compression stroke is included in the high load region and is not included in the low load region.

  FIG. 3 is a cross-sectional view showing a cross section perpendicular to the rotation axis of the starting generator 20 shown in FIG. The starter / generator 20 will be described with reference to FIGS. 2 and 3.

  The starter generator 20 is a permanent magnet type three-phase brushless motor. The starter generator 20 also functions as a permanent magnet type three-phase brushless generator.

The starter generator 20 includes a rotor 30 and a stator 40. The starter generator 20 of the present embodiment is a radial gap type. The starter generator 20 is an outer rotor type. That is, the rotor 30 is an outer rotor. The stator 40 is an inner stator.
The rotor 30 has a rotor main body 31. The rotor main body 31 is made of, for example, a ferromagnetic material. The rotor main body 31 has a bottomed cylindrical shape. The rotor main body 31 includes a cylindrical boss portion 32, a disk-shaped bottom wall portion 33, and a cylindrical back yoke portion 34. The bottom wall portion 33 and the back yoke portion 34 are integrally formed. The bottom wall portion 33 and the back yoke portion 34 may be configured separately. The bottom wall portion 33 and the back yoke portion 34 are fixed to the crankshaft 15 via the cylindrical boss portion 32. The rotor 30 is not provided with a winding to which current is supplied.

The rotor 30 has a permanent magnet part 37. The rotor 30 has a plurality of magnetic pole portions 37a. The plurality of magnetic pole portions 37 a are formed by permanent magnet portions 37. The plurality of magnetic pole portions 37 a are provided on the inner peripheral surface of the back yoke portion 34. In the present embodiment, the permanent magnet portion 37 has a plurality of permanent magnets. The plurality of magnetic pole portions 37a are provided in each of the plurality of permanent magnets.
The permanent magnet part 37 can also be formed by one annular permanent magnet. In this case, one permanent magnet is magnetized such that a plurality of magnetic pole portions 37a are arranged on the inner peripheral surface.

The plurality of magnetic pole portions 37 a are provided so that N poles and S poles are alternately arranged in the circumferential direction of the starting generator 20. In the present embodiment, the number of magnetic poles of the rotor 30 facing the stator 40 is 24. The number of magnetic poles of the rotor 30 refers to the number of magnetic poles facing the stator 40. No magnetic material is provided between the magnetic pole part 37a and the stator 40.
The magnetic pole portion 37 a is provided outside the stator 40 in the radial direction of the starting generator 20. The back yoke portion 34 is provided outside the magnetic pole portion 37a in the radial direction. The starter generator 20 has more magnetic pole portions 37 a than the number of tooth portions 43.
The rotor 30 may be an embedded magnet type (IPM type) in which the magnetic pole portion 37a is embedded in a magnetic material. However, as in this embodiment, the rotor 30 is a surface magnet type in which the magnetic pole portion 37a is exposed from the magnetic material. (SPM type) is preferable.

  A cooling fan F is provided on the bottom wall 33 constituting the rotor 30.

  The stator 40 has a stator core ST and a plurality of stator windings W. Stator core ST has a plurality of teeth 43 provided at intervals in the circumferential direction. The plurality of tooth portions 43 integrally extend from the stator core ST toward the radially outer side. In the present embodiment, a total of 18 tooth portions 43 are provided at intervals in the circumferential direction. In other words, the stator core ST has a total of 18 slots SL formed at intervals in the circumferential direction. The tooth portions 43 are arranged at equal intervals in the circumferential direction.

  The rotor 30 has a larger number of magnetic pole portions 37 a than the number of tooth portions 43. The number of magnetic pole portions 37a is 4/3 of the number of slots.

  A stator winding W is wound around each tooth portion 43. That is, the multiple-phase stator winding W is provided so as to pass through the slot SL. FIG. 3 shows a state in which the stator winding W is in the slot SL. Each of the multi-phase stator windings W belongs to one of the U phase, the V phase, and the W phase. For example, the stator windings W are arranged in the order of the U phase, the V phase, and the W phase. The winding method of the stator winding W may be concentrated winding or distributed winding, and is not particularly limited, but concentrated winding is preferable.

  A plurality of detected parts 38 for detecting the rotational position of the rotor 30 are provided on the outer surface of the rotor 30. The plurality of detected parts 38 are detected by a magnetic action. The plurality of detected portions 38 are provided on the outer surface of the rotor 30 at intervals in the circumferential direction. The detected portion 38 is made of a ferromagnetic material.

  The rotor position detection device 50 is a device that detects the position of the rotor 30. The rotor position detection device 50 is provided at a position facing the plurality of detected parts 38.

The starter generator 20 is connected to the crankshaft 15 of the engine 10. Specifically, the rotor 30 is connected to the crankshaft 15 so as to rotate at a fixed speed ratio with respect to the crankshaft 15.
In this embodiment, the rotor 30 is attached to the crankshaft 15 without a power transmission mechanism (for example, a belt, a chain, a gear, a speed reducer, a speed increaser, etc.). The rotor 30 rotates with respect to the crankshaft 15 at a speed ratio of 1: 1. The starter / generator 20 is configured to rotate the crankshaft 15 in the forward direction by the forward rotation of the engine 10.

Note that the starter generator 20 may be attached to the crankshaft 15 via a power transmission mechanism. However, the starter generator 20 is connected to the crankshaft 15 without any speed variable transmission or clutch. That is, the starter / generator 20 is connected to the crankshaft 15 without a device having a variable input / output speed ratio.
In the present invention, it is preferable that the rotation axis of the starter generator 20 and the rotation axis of the crankshaft 15 substantially coincide. Moreover, it is preferable that the starter generator 20 is attached to the crankshaft 15 without using a power transmission mechanism as in the present embodiment.

The starter generator 20 starts the engine 10 by rotating the crankshaft 15 forward when the engine is started. The starter generator 20 is driven by the engine 10 to generate power when the engine 10 performs a combustion operation. That is, the starter / generator 20 has both a function of starting the engine 10 by rotating the crankshaft 15 forward and a function of generating power by being driven by the engine 10 when the engine 10 performs a combustion operation. The starter / generator 20 is rotated forward by the crankshaft 15 and functions as a generator during at least a part of the period after the engine 10 is started. That is, when the starter / generator 20 functions as a generator, the starter / generator 20 need not always function as a generator after the combustion of the engine 10 is started. Further, after the start of combustion of the engine 10, a period in which the starter / generator 20 functions as a generator and a period in which the starter / generator 20 functions as a vehicle drive motor may be included.
In the vehicle 1 of the present embodiment, the member that transmits the rotational power from the engine 10 to the wheel 3b includes only the starter generator 20 as a device that performs conversion between the rotational power and the electric power related to the driving of the wheel 3b. It has been. However, the vehicle of the present invention is not limited to this, and a device other than the starter generator that performs conversion between rotational power and electric power may be connected to a member that transmits rotational power from the engine to the driving member. .

The starter / generator 20 starts the engine 10 by rotating the crankshaft 15 forward when the engine is started. The starter / generator 20 rotates the crankshaft 15 in a forward direction in a state where the combustion operation of the engine 10 is stopped after the engine 10 is started. In these cases, it is advantageous that the starter / generator 20 has a larger outputable torque. As the output torque that can be output is larger, the crankshaft 15 having a larger load can be rotated forward. When the torque that can be output is large, the ability to exceed the load in the high load region when the engine is started is high.
However, in general, when the starter generator functions as a generator, if the output torque of the starter generator is improved, the generated current of the starter generator may increase. For example, when the magnetic force of the magnet included in the starter / generator is increased, the torque that can be output increases. Moreover, the output torque which can be output increases also by making comparatively wide the space | interval of the front-end | tip parts which oppose a stator among adjacent tooth parts. However, in these cases, the generated current of the starter generator becomes large when the starter generator is driven by the engine. As a result, after the engine is started, the charging current to the battery connected to the starter generator may become excessive. In this case, for example, the current flowing to the battery can be suppressed by controlling the inverter. At this time, a part of the current is converted into heat.
Thus, in the starter generator, there is a trade-off relationship between the improvement of the output torque and the suppression of the generated current. If one of the torque improvement and the generation current suppression is prioritized, the other characteristic is degraded.

The starter generator 20 of the present embodiment has more magnetic pole portions 37 a than the number of tooth portions 43.
For this reason, the starter generator 20 has a higher angular velocity than a starter generator having fewer magnetic poles than the number of teeth. Angular velocity contributes to the winding impedance.
That is, the winding impedance is roughly expressed by the following equation.
(R ² + ω ² L ² ) ^1/2
Where R: DC resistance, ω: angular velocity with respect to electrical angle, L: inductance

The angular velocity ω for the electrical angle is expressed by the following equation.
ω = (P / 2) × (N / 60) × 2π
Where P: number of magnetic poles, N: rotational speed [rpm]

Since the starter generator 20 has more magnetic pole portions 37a than the number of teeth 43, the angular velocity ω is higher than that of a starter generator having fewer magnetic poles than the number of teeth. Therefore, the impedance when rotating is large. In addition, as the rotational speed N increases, the angular speed ω increases and the impedance increases.
Therefore, the starting generator 20 can suppress the generated current by ensuring a large impedance in the rotation region used as the generator.

FIG. 4 is a block diagram showing a schematic electrical configuration of the vehicle 1 shown in FIG.
The vehicle 1 is provided with an inverter 61. The control device 60 controls each part of the vehicle 1 including the inverter 61.

  The starter generator 20 and the battery 4 are connected to the inverter 61. The battery 4 sends and receives current to the starter generator 20. A headlamp 7 is also connected to the inverter 61 and the battery 4. The headlamp 7 is an auxiliary device mounted on the vehicle 1 that operates while consuming electric power. Hereinafter, the headlamp 7 is also referred to as an auxiliary machine 7.

The battery 4 is connected to the inverter 61 and the headlamp 7 via the main switch 5.
A current sensor 64 is provided on a line connecting the battery 4 and the inverter 61. The current sensor 64 detects the current flowing through the battery 4. The current sensor 64 is provided between the battery 4 and the branch point to the headlamp 7 in the line connecting the battery 4 and the inverter 61.

The inverter 61 includes a plurality of switching units 611 to 616. The inverter 61 of the present embodiment includes six switching units 611 to 616.
The switching units 611 to 616 constitute a three-phase bridge inverter.
The plurality of switching units 611 to 616 are connected to each phase of the stator winding W having a plurality of phases.
More specifically, of the plurality of switching units 611 to 616, two switching units connected in series constitute a half bridge. Switching units 611 to 616 constituting the half-bridge of each phase are connected to each phase of a plurality of phases of stator winding W, respectively.
Switching units 611 to 616 switch current passing / cutting between the plurality of stator windings W and the battery 4.

Specifically, when the starter generator 20 functions as a motor, energization and deenergization of each of the plurality of phases of the stator winding W are switched by the on / off operations of the switching units 611 to 616.
Further, when the starter generator 20 functions as a generator, on / off operation of the switching units 611 to 616 switches between current passing / breaking between each of the stator windings W and the battery 4. By sequentially switching on and off the switching units 611 to 616, rectification of three-phase alternating current output from the starter generator 20 and voltage control are performed.

  Each of the switching units 611 to 616 includes a switching element. The switching element is, for example, a transistor, and more specifically, an FET (Field Effect Transistor). However, in addition to the FET, for example, a thyristor and an IGBT (Insulated Gate Bipolar Transistor) can also be used for the switching units 611 to 616.

  Current sensors 65 u and 65 w are provided on a line connecting the inverter 61 and the stator winding W. The current sensors 65u and 65w detect a two-phase current in the starter generator 20. The current sensors 65u and 65w are connected to the control device 60.

A fuel injection device 18, a spark plug 19, and a battery 4 are connected to the control device 60.
The control device 60 includes a starting power generation control unit 62 and a combustion control unit 63.

The starting power generation control unit 62 controls the operation of the starting generator 20 by controlling the on / off operations of the switching units 611 to 616. The start power generation control unit 62 includes a start control unit 621 and an assist control unit 622.
The combustion control unit 63 controls the combustion operation of the engine 10 by controlling the spark plug 19 and the fuel injection device 18. The combustion control unit 63 controls the rotational power of the engine 10 by controlling the spark plug 19 and the fuel injection device 18.
The control device 60 is composed of a computer having a central processing unit (not shown) and a storage device (not shown). The central processing unit performs arithmetic processing based on the control program. The storage device stores data relating to programs and operations.
The start power generation control unit 62 including the start control unit 621 and the assist control unit 622, and the combustion control unit 63 are realized by a computer (not shown) and a control program executed by the computer. Therefore, the operations of the starting power generation control unit 62 including the start control unit 621 and the assist control unit 622 and the combustion control unit 63, which will be described later, can be said to be operations of the control device 60. The starting power generation control unit 62 and the combustion control unit 63 may be configured as separate devices, for example, at positions separated from each other, or may be configured integrally.

A starter switch 6 is connected to the control device 60. The starter switch 6 is operated by the driver when the engine 10 is started. The starting power generation control unit 62 of the control device 60 detects the charge level of the battery 4. The starting power generation control unit 62 detects the charge level of the battery 4 by detecting the voltage and current of the battery 4.
The main switch 5 supplies power to the control device 60 according to the operation.

  The starting power generation control unit 62 and the combustion control unit 63 of the control device 60 control the engine 10 and the starting generator 20. The starting power generation control unit 62 controls the inverter 61.

FIG. 5 is a flowchart for explaining the operation of the vehicle 1.
The operation of the vehicle 1 will be described with reference to FIGS.

  The operation of the vehicle 1 is controlled by the control device 60.

After starting the engine 10 (S11), the control device 60 determines whether or not an acceleration instruction is input (S12). Specifically, at the start of the engine in step S <b> 11, the start control unit 621 of the start power generation control unit 62 starts the engine 10.
Specifically, the start control unit 621 causes the starter generator 20 to drive the crankshaft 15. The start control unit 621 turns on / off the plurality of switching units 611 to 616 included in the inverter 61 so that a current that causes the rotor 30 to rotate forward is supplied to the plurality of stator windings W. As a result, the starter / generator 20 drives the crankshaft 15. Further, the combustion control unit 63 of the control device 60 causes the fuel injection device 18 to supply fuel. The combustion control unit 63 causes the spark plug 19 to ignite.
The start control unit 621 determines whether the engine 10 is started based on, for example, the rotational speed of the crankshaft 15. For example, the start control unit 621 acquires the rotational speed of the crankshaft 15 from the detection result of the rotor position detection device 50.

In the determination of the acceleration instruction in step S12, the control device 60 determines whether or not the acceleration of the vehicle 1 is instructed by the accelerator operation element 8.
When the acceleration of the vehicle 1 is instructed (Yes in S12), the control device 60 increases the rotational power of the engine 10 to the fuel injection device 18 as the engine output adjusting unit (S13). At the same time, the control device 60 controls the inverter 61 so that the starter / generator 20 drives the crankshaft 15 with the electric power of the battery 4 (S15). As a result, the engine 10 is assisted by the starter generator 20.

  More specifically, when acceleration of the vehicle 1 is instructed by the accelerator operator 8, the control device 60 causes the starter generator 20 to drive the crankshaft 15 during a predetermined assist period. The assist period is a period after the starter / generator 20 starts driving the crankshaft 15 when the vehicle 1 is instructed to accelerate. The assist period is set according to the capacity of the battery 4 so that the charge level of the battery 4 does not decrease too much.

  When the acceleration of the vehicle 1 is instructed (Yes in S12) and during the assist period (S14), the control device 60 causes the starter generator 20 to drive the crankshaft 15 with the electric power of the battery 4. 61 is controlled (S15). Specifically, the assist control unit 622 of the starter power generation control unit 62 controls the inverter 61 so that the starter generator 20 drives the crankshaft 15.

  The starter generator 20 assists the engine 10 by driving the crankshaft 15 with the electric power of the battery 4. For this reason, acceleration of the crankshaft 15 accompanying the increase in the rotational power of the engine 10 is further promoted.

In step S15, the assist control unit 622 controls the inverter 61 so as to perform field weakening control on the starter generator 20.
Control of the inverter 61 by the control device 60 will be described.
When the rotor 30 having the magnetic pole portion 37 a rotates together with the crankshaft 15, an induced electromotive voltage is generated in the stator winding W of the starting generator 20 due to a change in magnetic flux of the magnetic pole portion 37 a interlinked with the stator winding W. The induced electromotive voltage hinders supply of current from the battery 4 to the starter generator 20. The induced electromotive voltage increases as the rotational speed of the crankshaft 15 increases. On the other hand, the voltage of the battery 4 mounted on the vehicle 1 is lower than the voltage of the commercial power source, for example. For this reason, as the rotational speed of the crankshaft 15 increases, the current flowing from the battery 4 to the starter generator 20 decreases. Therefore, as the rotational speed of the crankshaft 15 increases, the output torque of the starter generator 20 decreases.

  In the vehicle 1 of the present embodiment, the assist control unit 622 controls the inverter 61 so that the starter generator 20 drives the crankshaft 15 while performing field weakening control on the starter generator 20. In the field-weakening control, the assist control unit 622 causes a current to flow through the stator winding W so that a magnetic flux in a direction opposite to the direction of the magnetic flux of the magnetic pole portion 37a that generates the induced electromotive force is generated.

  FIG. 6A is an explanatory diagram schematically showing the drive characteristics of the starter generator. FIG. 6B is an explanatory diagram schematically showing power generation characteristics.

  The horizontal axis in FIGS. 6A and 6B indicates the rotational speed of the crankshaft 15. The vertical axis in FIG. A solid line Ta indicates an output torque characteristic of the starting generator 20 when the field weakening control is performed. A broken line Tb indicates an output torque characteristic when the field weakening control is not performed. The vertical axis | shaft of FIG. 6 (B) is an electric current.

Specifically, the output torque characteristic Tb indicates the maximum drive torque that can be output by the starter / generator 20 at the voltage of the battery 4 at a certain rotational speed when the field weakening control is not performed. The starter / generator 20 can output drive torque in a range indicated by hatching in accordance with control.
As the rotational speed of the crankshaft 15 increases, the induced electromotive voltage increases. For this reason, the maximum current that can be supplied from the battery 4 to the starter generator 20 decreases. Therefore, as the output torque characteristic Tb indicates, the maximum drive torque that can be output decreases as the rotational speed of the crankshaft 15 increases. The output torque characteristic Tb is also restricted by the rated current of the battery 4 or the inverter 61. However, in FIG. 6A, in order to show the influence of the induced electromotive voltage in an easy-to-understand manner, the restrictions due to the rated current and the like are ignored.
In FIG. 6A, when the torque is larger than 0, that is, when the torque is positive, the starting generator 20 drives the crankshaft 15 in the forward rotation direction. In this case, the starter / generator 20 assists the engine 10 by driving the crankshaft 15 with the electric power of the battery 4.
In a situation where the engine 10 is assisted, for example, the rotational power of the engine 10 is increased due to an increase in fuel supply (see S13 in FIG. 5). Therefore, the torque with which the rotational power of the engine 10 rotates the crankshaft 15 increases with the rotational speed.
On the other hand, the output torques Ta and Tb of the starting generator 20 decrease as the rotational speed of the crankshaft 15 increases.

For example, when the field-weakening control is not performed and the rotation speed of the crankshaft 15 increases, the torque at which the starter generator 20 drives the crankshaft 15 with the power of the battery 4 and the rotation power of the engine 10 rotate the crankshaft 15. The torque to be applied is equal at the rotational speed Nb. The torque at which the starter / generator 20 drives the crankshaft 15 at the rotational speed Nb is zero.
When the field weakening control is not performed, the rotational speed Nb at which the torque at which the starter / generator 20 drives the crankshaft 15 with the power of the battery 4 is equal to the torque at which the rotational power of the engine 10 rotates the crankshaft 15 is normally Also referred to as the power running upper limit speed Nb. The normal power running upper limit speed Nb is a value obtained in advance by measurement, simulation, or the like. The normal power running upper limit speed Nb is stored in a storage device (not shown), for example.

For example, when the field weakening control is not performed, the output torque of the starter generator 20 becomes negative in a situation where the rotational speed of the crankshaft 15 is larger than the normal power running upper limit speed Nb. That is, in this case, the starter generator 20 is driven by the engine 10. In this case, the battery 4 is charged by the power generated by the starter generator 20. A broken line in FIG. 6B indicates a current that can be supplied from the starter / generator 20 to the battery 4 via the inverter 61 when the field weakening control is not performed. However, the current actually supplied from the starting generator 20 to the battery 4 is controlled by the inverter 61.
When the inverter 61 normally shifts to power generation control, the current that is actually supplied from the starter generator 20 to the battery 4 is limited to the rated current of the battery 4 or less. When the inverter 61 is controlled to perform a boost operation, the battery 4 can be charged by the generated power of the starter generator 20 even at a rotational speed lower than the normal power running upper limit speed Nb.

  In the vehicle 1 of the present embodiment, the inverter 61 is controlled to perform field-weakening control on the starter generator 20. Therefore, as indicated by the solid line Ta, the starter generator 20 can output torque at a higher speed than when the field weakening control is not performed. That is, the maximum driving speed Na that can drive the crankshaft 15 with the electric power of the battery 4 is higher than the normal power running upper limit speed Nb when the field-weakening control is not performed.

For example, when the field weakening control is not performed, the output torque at the rotation speed Nb is zero as shown by the broken line Tb in FIG. When field-weakening control is not performed, an induced electromotive voltage having a magnitude that prevents current from flowing through the stator winding W is generated by the voltage of the battery 4 at the rotational speed Nb.
When the field weakening control is performed, the magnetic flux of the magnetic pole portion 37a of the starting generator 20 is weakened. This can be said to be equivalent to a decrease in the magnetic force of the magnetic pole portion 37a. As a result, a current that contributes to torque can flow through the stator winding W at a rotational speed that is equal to or lower than the maximum drive speed Na.
The torque characteristics Ta and the maximum drive speed Na when the field weakening is performed correspond to the degree of field weakening. For example, the torque characteristic Ta and the maximum drive speed Na correspond to the magnitude of the d-axis current described later. The relationship between the maximum driving speed Na and the degree of field weakening can be obtained in advance by measurement or simulation. For example, the maximum driving speed Na and the degree of field weakening are associated with each other and stored in a storage device (not shown).

  The starter generator 20 can rotate the crankshaft 15 at the maximum drive speed Na when the starter generator 20 drives the crankshaft 15 with the electric power of the battery 4 while performing field-weakening control. By the field weakening control, the starter generator 20 can drive the crankshaft 15 with the electric power of the battery 4 at a higher rotational speed. For this reason, acceleration of the crankshaft 15 when the rotational power of the engine 10 increases is further promoted. Therefore, the drivability of the vehicle 1 is improved.

  The control device 60 in the present embodiment controls the inverter 61 so as to drive the crankshaft 15 by vector control.

Vector control is a method of controlling the current of the starting generator 20 by separating it into a d-axis component (d-axis current) and a q-axis component (q-axis current). The d-axis component is a component corresponding to the magnetic flux direction in the magnetic pole pair formed by the magnetic pole portion 37a (FIG. 3). The q-axis component is a component perpendicular to the magnetic flux direction in the electrical angle. The q-axis component affects the torque load of the starting generator 20. The q-axis component affects the field, that is, the magnetic field generated by the magnetic pole portion 37a. The field weakening is performed by the q-axis component.
The vector control is a control for energizing each phase of the plurality of phases of the stator winding W without energization pause. The vector control is a control in which energization is performed so that a sine wave current flows in each phase of the stator winding W of a plurality of phases. When the plurality of switching units 611 to 616 are turned on / off at the timing of vector control, a sine wave current flows through each of the plurality of stator windings W. Power generation by vector control is realized, for example, by drawing a current in the direction of the induced electromotive voltage so as to synchronize with the sine wave of the induced electromotive voltage of the stator winding W. The sine wave current and the sine wave voltage mean a sine wave current and voltage. The sine wave current includes, for example, ripple and distortion associated with the on / off operation of the switching units 611 to 616.
In the vector control, each of the plurality of switching units 611 to 616 is controlled by a signal subjected to pulse width modulation (PWM). The period of the pulse in the pulse width modulation is shorter than the period of the induced electromotive voltage of each phase of the stator winding W. That is, the control device 60 controls on / off of the plurality of switching units 611 to 616 according to a pulse signal having a cycle shorter than the cycle of the induced electromotive voltage of the stator winding W of the starter generator 20.

In the vector control, the assist control unit 622 calculates the d axis based on the currents Ufb and Wfb of the stator windings W of the plurality of phases detected by the current sensors 65u and 65w and the position θ of the rotor 30 detected by the rotor position detection device 50. Get the component and q-axis component. The control device 60 controls the on / off timings of the plurality of switching units 611 to 616 based on the component corrected according to the target value.
In the control, a method of detecting the current of the three-phase stator winding can also be employed. In the control, a method of omitting position detection by the rotor position detection device 50 can be employed. Moreover, in control, the method of controlling the some switching parts 611-616 is also employable, without detecting the electric current of the stator winding of any phase directly.
For the on / off timing control, for example, a method of calculating an expression using input information or a method of reading and referring to a map (setting table) stored in a storage unit can be employed. Expressions or maps may be included in the program.

FIG. 7 is a block diagram illustrating an outline of vector control.
In the vector control, the starting power generation control unit 62 performs feedback control using the current converted into the d-axis component and the q-axis component.
More specifically, the starting power generation control unit 62 obtains the current of the stator winding W of each phase based on the currents Ufb and Wfb flowing in the stator winding W of each phase detected by the current sensors 65u and 65w. The starting power generation control unit 62 performs three-phase to two-phase conversion of the current of the stator winding W of each phase with respect to the position θ of the rotor 30 detected by the rotor position detection device 50. In the three-phase to two-phase conversion, the rotation coordinates are also converted into orthogonal coordinates. Thereby, the d-axis conversion current id_fb and the q-axis conversion current iq_fb representing the current current on the dq axis model are obtained. The d-axis conversion current id_fb and the q-axis conversion current iq_fb are feedback values for control.
The starting power generation control unit 62 calculates a deviation of the d-axis conversion current id_fb from the d-axis target current id and a deviation of the q-axis conversion current iq_fb from the q-axis target current iq. Thereby, the starting power generation control unit 62 calculates the d-axis target voltage and the q-axis target voltage for making each deviation zero. The starting power generation control unit 62 obtains U-phase, V-phase, and W-phase voltage commands U *, V *, and W * by performing two-phase to three-phase conversion on the d-axis target voltage and the q-axis target voltage. In the two-phase to three-phase conversion, conversion from orthogonal coordinates to rotational coordinates is also performed. The starting power generation control unit 62 generates a PWM signal according to the voltage commands U *, V *, and W *. The starting power generation control unit 62 outputs a PWM signal to the inverter 61. Specifically, the starting power generation control unit 62 controls the switching units 611 to 616 (FIG. 4) of the inverter 61 with the generated PWM signal.

By the vector control, the current of the starter generator 20 that is a three-phase brushless motor can be set in the form of a d-axis target current id and a q-axis target current iq that are direct currents.
In step S15 of FIG. 5, the assist control unit 622 sets the q-axis target current according to the acceleration amount of the vehicle 1 instructed by the accelerator operator 8. As a result, the q-axis current is controlled.
Further, the assist control unit 622 sets the d-axis target current based on the speed of the crankshaft 15. As a result, the d-axis current is controlled. Field weakening control is performed by setting the d-axis target current. The strength of field weakening control is controlled by the magnitude of the d-axis current.

In FIG. 6A, a solid line Ta indicates an output torque characteristic of the starter generator 20 in field weakening control. Na indicates the maximum drive speed at which the crankshaft 15 can be driven by the electric power of the battery 4.
The inclination of the output torque Ta and the magnitude of the maximum drive speed Na differ depending on the magnitude of the d-axis current.

In step S <b> 15 of FIG. 5, the assist control unit 622 sets the d-axis target current so that the maximum drive speed Na is larger than the actual rotational speed of the crankshaft 15. That is, the assist control unit 622 performs field-weakening control so that the maximum drive speed Na is higher than the actual rotation speed of the crankshaft 15.
In this manner, in step S15, the assist control unit 622 controls the inverter 61 so that the starter generator 20 drives the crankshaft 15 with the electric power of the battery 4 while performing field weakening on the starter generator 20. .
For this reason, the acceleration of the crankshaft 15 accompanying the increase in the rotational power of the engine 10 is assisted by a large torque at a higher rotational speed.

In step S12 of FIG. 5, the control device 60 determines whether or not there is an acceleration instruction. When there is no instruction for acceleration (No in S12), the control device 60 determines stop of the acceleration instruction (S16).
When the acceleration instruction is stopped (Yes in S16), the control device 60 causes the fuel injection device 18 to reduce the rotational power (S17). Specifically, the control device 60 reduces the amount of fuel supplied to the fuel injection device 18. Further, in the present embodiment, when the accelerator operator 8 (see FIG. 1) is operated so as to stop the acceleration instruction, the amount of air by the throttle valve SV also decreases.

When the acceleration instruction is stopped (Yes in S16), the control device 60 determines whether or not the rotational speed of the crankshaft 15 exceeds the normal power running upper limit speed Nb (FIG. 6) (S18).
The shaded area in FIG. 6A indicates the driving force that allows the starter generator 20 to drive the crankshaft 15 with the power of the battery 4 when field-weakening control is not performed. A broken line Tb indicates the maximum driving force with which the starter / generator 20 can drive the crankshaft 15 with the electric power of the battery 4 when the field weakening control is not performed. That is, the broken line Tb indicates the maximum driving force with which the starter generator 20 can drive the crankshaft 15 at the corresponding rotational speed when the field weakening control is not performed.
While the rotational speed of the crankshaft 15 is increasing, at the normal power running upper limit speed Nb, the maximum driving force by the starter generator 20 and the rotational power that causes the rotational power of the engine 10 to rotate the crankshaft 15 become substantially equal.
In step S18, the control device 60 determines whether or not the actual rotational speed of the crankshaft 15 is greater than the normal power running upper limit speed Nb.

When the actual rotational speed of the crankshaft 15 exceeds the normal power running upper limit speed Nb (Yes in S18), the control device 60 reduces the driving force by the starter generator 20 while controlling overvoltage prevention. (S21). Here, when the actual rotational speed exceeds the normal power running upper limit speed Nb, it means that the actual rotational speed is in the region to the right of the line NB in FIG.
In step S <b> 21, the assist control unit 622 controls the inverter 61 so that an overvoltage due to the rotation of the crankshaft 15 is not applied. Specifically, the control device 60 reduces the driving force of the crankshaft 15 to the starter generator 20 while continuing field-weakening control so that an overvoltage resulting from the rotation of the crankshaft 15 is not applied to the switching units 611 to 616. . The overvoltage is a voltage higher than the voltage of the battery 4. In the present embodiment, the control device 60 causes the starter generator 20 to reduce the driving force of the crankshaft 15 while maintaining the d-axis current. The controller 60 decreases the driving force by decreasing the q-axis current.
For example, the control device 60 causes the starter generator 20 to stop driving the crankshaft 15. The control device 60 decreases the q-axis current while maintaining the d-axis current.
In step S <b> 21, the assist control unit 622 sets the d-axis target current so that the maximum drive speed Na is larger than the actual rotation speed of the crankshaft 15. That is, the assist control unit 622 performs field-weakening control so that the maximum drive speed Na is higher than the actual rotation speed of the crankshaft 15.
Specifically, the assist control unit 622 weakens the field weakening control as the rotational speed of the crankshaft 15 decreases. More specifically, the assist control unit 622 decreases the d-axis current according to the decrease in the rotation speed of the crankshaft 15. This weakens field weakening control. The d-axis current is a current that originally does not contribute to torque. By reducing the d-axis current, power efficiency is improved.

In step S18, when the actual rotational speed of the crankshaft 15 does not exceed the rotational speed Nb (No in S18), the assist control unit 622 reduces the driving force by the starter generator 20 without preventing overvoltage. (S22).
Specifically, the assist control unit 622 stops the field weakening control and causes the starter generator 20 to reduce the driving force of the crankshaft 15. More specifically, the assist control unit 622 reduces the driving force by setting the d-axis current to zero and decreasing the q-axis current.

  When the acceleration instruction is not stopped in step S16 (No in S16), the control device 60 performs basic control (S23). In the basic control, the control device 60 controls the inverter 61 to perform power generation according to the rotation state of the starter generator 20.

  As described above, in the vehicle 1 of the present embodiment, when the acceleration of the vehicle 1 is instructed, the control device 60 causes the fuel injection device 18 to increase the rotational power of the engine 10 (S13). At the same time, the control device 60 controls the inverter 61 so that the starter generator 20 drives the crankshaft 15 with the electric power of the battery 4 while performing field weakening control on the starter generator 20 (S15). For this reason, the starter / generator 20 outputs a large torque at a higher rotational speed than when the field weakening control is not performed, for example. Therefore, the crankshaft 15 is driven more strongly by the starter generator 20 at a high rotational speed. That is, the engine 10 is assisted by the starter / generator 20 at a high rotational speed. As a result, the drivability of the vehicle 1 is improved.

The engine 10 is assisted by the starter / generator 20 in response to an input of an acceleration instruction. The acceleration instruction is input by operating the accelerator operation element 8 by the driver.
During the assist by the starter / generator 20, the acceleration instruction may be stopped by the operation of the accelerator operator 8.

  In the vehicle 1 of the present embodiment, when the acceleration instruction is stopped (Yes in S16 of FIG. 5), the control device 60 causes the fuel injection device 18 to reduce the rotational power of the engine 10 (S17), and the starting power generation The inverter 61 is controlled so that the driving force of the crankshaft 15 is reduced in the machine 20 (S21).

In order to reduce the driving force of the starter generator 20, for example, it is conceivable to stop supplying current from the inverter 61 to the starter generator 20. Specifically, it can be considered that the d-axis current and the q-axis current supplied to the starter generator 20 are made zero.
The starter generator 20 is connected to the crankshaft 15 of the engine 10. The crankshaft 15 of the engine 10 has a large inertia. For this reason, even if the rotational power is reduced by the fuel injection device 18 and the current supplied to the starter generator 20 becomes zero, the rotation of the crankshaft 15 does not stop immediately. The rotation of the crankshaft 15 continues due to inertia. That is, the rotation of the crankshaft 15 continues at least for a certain period after the vehicle acceleration instruction is stopped.
As the crankshaft 15 rotates, an induced electromotive voltage is generated in the starter generator 20. During the assist by the starter / generator 20, the influence of the induced electromotive voltage is suppressed to such an extent that the inverter 61 can be controlled by the voltage of the battery 4 of the vehicle 1 by field weakening control. However, when the supply of current to the starter generator 20 is stopped, for example, by stopping the acceleration instruction, the influence of the induced electromotive voltage increases rapidly.

FIG. 8A is an explanatory diagram schematically illustrating the drive characteristics of the starter generator 20 during field-weakening control. FIG. 8B is an explanatory diagram schematically showing power generation characteristics during field-weakening control.
In the vehicle 1 of the present embodiment, the inverter 61 is controlled to perform field-weakening control on the starter generator 20 while the engine 10 is assisting. Therefore, as indicated by the solid line Ta, the starter generator 20 can output torque.
FIG. 8A shows the position of torque when the rotational speed of the crankshaft 15 is Nc, for example. In FIG. 8A, the voltage relationship at the rotational speed Nc of the crankshaft 15 is shown as a voltage vector diagram.
V indicates the magnitude of the voltage of the battery 4. E represents an induced electromotive voltage. Id indicates a d-axis current. Iq indicates a q-axis current. ω represents an angular velocity in electrical angle. R represents the resistance of the stator winding W. L indicates the inductance of the stator winding W.
The rotational speed Nc is larger than the normal power running upper limit speed Nb. An induced electromotive voltage E higher than the voltage of the battery 4 is generated in the stator winding W of the starting generator 20. However, the magnitude of the voltage Vt applied to the switching units 611 to 616 of the inverter 61 by field weakening control is equal to the magnitude of the voltage V of the battery 4. The voltage Vt applied to the switching units 611 to 616 of the inverter 61 is equal to the terminal voltage Vt of the stator winding W. Specifically, the magnitude of the voltage Vt obtained by combining the induced voltage E with the voltage drops Iq · R, Iq · ωL of the q-axis current Iq and the voltage drops Id · R, Id · ωL of the d-axis current Id, It is equal to the voltage V of the battery 4. In this case, the current flowing through the starter generator 20 by the inverter 61 can be controlled. The inverter 61 is controlled so that the starter / generator 20 outputs torque for rotating the crankshaft 15 with the electric power of the battery 4 at the rotational speed Nc.

FIG. 9A is an explanatory diagram schematically showing the drive characteristics of the starter generator 20 when the acceleration instruction is stopped. FIG. 9B is an explanatory diagram schematically showing power generation characteristics when the acceleration instruction is stopped. FIG. 9A shows the voltage relationship when the d-axis current and the q-axis current become zero.
For example, in the situation where the crankshaft 15 is accelerated to the rotational speed Nc, when the supply of current to the starter generator 20 is stopped, the voltage applied to the switching units 611 to 616 becomes the induced electromotive voltage E. The voltage applied to the switching units 611 to 616 is greater than the voltage V of the battery 4. That is, the terminal voltage of the stator winding W becomes an induced electromotive voltage E higher than the voltage V of the battery 4. This can be said to be equivalent to the elimination of the decrease in the magnetic force of the magnetic pole portion 37a due to the field weakening. In this case, the inverter 61 cannot control the starter generator 20. In this case, the inverter 61 cannot appropriately limit the current flowing from the starting generator 20 to the battery 4. There is a possibility that the current Ic shown in FIG. The magnitude of the current Ic flowing through the battery 4 may exceed the allowable current of the battery 4 mounted on the vehicle 1. Further, when the supply of current to the starting generator 20 is stopped, the magnetic flux changes abruptly. Therefore, an induced electromotive voltage larger than the voltage indicated by E in FIG. 9A may be generated in the stator winding W. That is, a large induced electromotive voltage may be applied to the inverter 61 and the battery 4. A large current may flow through the battery 4 due to a large induced electromotive voltage due to a sudden change in magnetic flux.
As a result, a current exceeding the allowable current of the battery 4 may flow through the battery 4. In addition, a voltage exceeding the rated voltage may be applied to the switching units 611 to 616 of the inverter 61. In addition, the power of the switching units 611 to 616 due to the current flowing through the switching units 611 to 616 may exceed the rated power.

In the vehicle 1 of the present embodiment, when the acceleration instruction is stopped, the control device 60 reduces the driving force by the starter / generator 20 while controlling overvoltage prevention (S21 in FIG. 5). Specifically, in the vehicle 1, the control device 60 decreases the q-axis current Iq while maintaining the d-axis current Id in the voltage vector diagram of FIG. That is, the control device 60 causes the starter generator 20 to transmit the crankshaft 15 while continuing the field weakening control so that the voltage V higher than the voltage V of the battery 4 due to the rotation of the crankshaft is not applied to the switching units 611 to 616. Reduce the driving force. For this reason, generation | occurrence | production of the situation where the induced electromotive voltage resulting from continuous rotation of the crankshaft 15 affects the battery 4 and the some switching parts 611-616 can be suppressed.
Specifically, since the d-axis current Id is maintained in the voltage vector diagram of FIG. 8, the voltage applied to the switching units 611 to 616 is smaller than the voltage V of the battery 4 even when the q-axis current Iq is decreased. Maintained. Therefore, the switching units 611 to 616 can maintain the control state of the current flowing from the starter generator 20 to the battery 4. By appropriate control of the switching units 611 to 616, the current flowing from the starting generator 20 to the battery 4 can be adjusted to be equal to or lower than the rated current of the battery 4.

  Further, when reducing the driving force by the starter / generator 20, the control device 60 weakens the field weakening control according to the decrease in the rotational speed of the crankshaft 15. For this reason, the power consumption can be suppressed by the amount that the field weakening control is weakened.

  In addition, when the rotational speed of the crankshaft 15 exceeds the normal power running upper limit speed Nb (Yes in S18 in FIG. 5), the control device 60 controls the overvoltage prevention and controls the driving force generated by the starter generator 20. Reduction is performed (S21 in FIG. 5). The control device 60 performs overvoltage prevention control in a situation where a relatively high induced electromotive voltage is likely to be generated in the starting generator 20. Therefore, current consumption for field weakening control can be suppressed.

FIG. 8A shows the maximum possible rotation of the crankshaft 15 when the crankshaft 15 is driven by the power of the battery 4 while the field weakening control is performed on the starter generator 20. The driving speed Na is shown. The maximum drive speed Na changes according to the degree of field weakening.
In step S21 of FIG. 5, the control device 60 performs field weakening control on the starter generator 20 so that the maximum drive speed Na becomes larger than the actual rotational speed of the crankshaft 15. Specifically, the assist control unit refers to the relationship between the maximum drive speed Na stored in a storage device (not shown) and the degree of field weakening. The assist control unit performs field weakening to the extent corresponding to the maximum drive speed Na that is higher than the actual rotation speed. Thus, field weakening control is performed so that excessive voltage generation is suppressed.

As shown in FIG. 3, the starter generator 20 included in the vehicle 1 of the present embodiment has more magnetic pole portions 37 a than the number of teeth 43. For this reason, the magnetic pole part 37a is small compared with the structure which has the magnetic pole part below the number of teeth, for example. Therefore, the influence of the field weakening at the magnetic pole portion 37a by the field weakening control is large. That is, the magnetic flux of the magnetic pole portion 37a is easily weakened by the magnetic field of the stator winding W through which the d-axis current flows.
Since the starter generator 20 has more magnetic pole portions 37a than the number of tooth portions 43, the angular velocity based on the electrical angle of the starter generator is compared with a configuration having magnetic pole portions equal to or less than the number of tooth portions. ω is large. Therefore, excessive current and voltage are greatly suppressed by field weakening control.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the following description of the second embodiment, the reference numerals referred to in the first embodiment are used, and differences from the first embodiment described above will be mainly described.

  FIG. 10 is a flowchart for explaining the operation of the vehicle according to the second embodiment of the present invention.

The content of step S21 of the control device 60 in the present embodiment is different from that in the first embodiment described above.
In step S21, the control device 60 of the present embodiment causes the starter generator 20 to reduce the driving force of the crankshaft 15 while short-circuiting each phase of the starter generator 20. Thereby, the control device 60 controls the inverter 61 so that the overvoltage resulting from the rotation of the crankshaft 15 is not applied from the starter / generator 20 to the battery 4 and the plurality of switching units 611 to 616. Specifically, the control device 60 turns on the switching units 612, 614, and 616 connected to the ground line among the switching units 611 to 616 illustrated in FIG. As a result, the three-phase stator winding W of the starter generator 20 is short-circuited. Therefore, the induction machine voltage of the stator winding W is not applied to the battery 4. Specifically, the voltage applied to the switching units 611 to 616 is equal to the voltage drop caused by the current flowing through the switching units 612, 614, and 616 in the on state. That is, the voltage applied to the switching units 611 to 616 from the starting generator 20 is substantially zero.
Further, when the three-phase stator winding W is short-circuited, the driving force by the starter generator 20 is reduced.

  As described above, according to the present embodiment, when the three-phase stator winding W is short-circuited, a voltage caused by the rotation of the crankshaft 15 greater than the voltage of the battery 4 is applied to the plurality of switching units 611 to 616. Not applied. In addition, when the three-phase stator winding W is short-circuited, the starting generator 20 reduces the driving force of the crankshaft 15.

  In the first embodiment described above, an example of field weakening control for the starter generator has been described as control for reducing the drive force of the crankshaft to the starter generator without applying an overvoltage resulting from rotation of the crankshaft. Moreover, 2nd embodiment demonstrated the example which short-circuits a stator winding. The controller in the present invention may perform both field weakening control and stator winding short-circuiting. For example, the control device may select one of field weakening control and stator winding short-circuiting according to the rotational speed of the crankshaft.

Further, in the first embodiment described above, the example of the control for supplying the d-axis current using the vector control as the field weakening control for the starter generator has been described. The method for controlling the inverter is not limited to vector control, and may be a so-called 120-degree energization method, for example.
The 120-degree energization method is a method in which energization for a period of 120 degrees in electrical angle and energization stop for a period of 60 degrees are repeated. The control device performs, for example, pulse width modulation (PWM) control of the switching unit of the inverter in the 120-degree energization control. The control device repeats the energization period and the non-energization period in each of the three phases. The control device turns on the switching unit corresponding to the energization period with a pulse width modulated signal. The period of the pulse is shorter than the repetition period of the energization period and the non-energization period. The control device controls the current flowing through the stator winding by adjusting the duty ratio in PWM. As a result, the torque output from the starter generator is mainly controlled.
The control device performs the field weakening control by performing the advance angle control in the control by the 120-degree energization method. The control device advances the timing of the energization period and the non-energization period in the advance angle control. Thus, field weakening control is performed. By the field weakening control, an induced electromotive voltage generated in the stator winding is suppressed. For this reason, the control device can rotate the crankshaft in a higher rotation speed region than in the case where the advance angle control is not performed. The extent to which the induced electromotive voltage is suppressed is mainly controlled by the extent to which the timing of the energization period and the non-energization period is advanced.
When the acceleration instruction is stopped by the operation of the accelerator operation element, for example, the control device decreases the duty ratio while performing advance angle control. That is, the control device decreases the duty ratio while maintaining the early timing of the energization period and the non-energization period.
By maintaining the advance angle control, it is possible to suppress the occurrence of a situation in which the induced electromotive voltage caused by the continuous rotation of the crankshaft affects the battery and the plurality of switching units when the acceleration instruction is stopped.

  In the first embodiment described above, the example in which the control device 60 weakens the field weakening control according to the decrease in the rotation speed of the crankshaft 15 has been described. However, the present invention is not limited to this, and the control device may maintain the magnitude of the d-axis current constant until, for example, the rotational speed of the crankshaft decreases to a predetermined speed.

  In the first embodiment described above, the example in which the starter generator 20 drives the crankshaft 15 during a predetermined assist period when the acceleration of the vehicle 1 is instructed has been described. However, the present invention is not limited to this, and the starter generator 20 may drive the crankshaft 15 whenever the acceleration of the vehicle 1 is instructed.

  In the above-described embodiment, an example in which a rotor having a plurality of magnetic pole portions larger than the number of tooth portions has been described. However, this invention is not limited to this, A rotor may have a magnetic pole part below the number of teeth.

  In the above-described embodiment, the case where the engine 10 is a single cylinder engine has been described. However, the engine of the present invention is not particularly limited as long as the engine has a high load region and a low load region. That is, a multi-cylinder engine may be used. Examples of the multi-cylinder engine include in-line two-cylinder, parallel two-cylinder, V-type two-cylinder, and horizontally opposed two-cylinder engines. The number of cylinders of the multi-cylinder engine is not particularly limited, and the multi-cylinder engine may be, for example, a four-cylinder engine.

  In the above-described embodiment, an example of a motorcycle as a vehicle has been described. The vehicle is not particularly limited, and examples thereof include scooter type, moped type, off-road type, and on-road type motorcycles. Further, the vehicle is not limited to a motorcycle, and may be, for example, an ATV (All-Train Vehicle). Further, the vehicle is not limited to a saddle-ride type vehicle, and may be a four-wheel vehicle having a passenger compartment. The vehicle according to the present invention is not limited to a vehicle with wheels, and may be a ship having a screw, for example.

  The terms and expressions used in the above embodiments are used for explanation and are not used for limited interpretation. It should be recognized that any equivalents of the features shown and described herein are not excluded and that various modifications within the claimed scope of the invention are permitted. The present invention can be embodied in many different forms. This disclosure should be regarded as providing embodiments of the principles of the invention. The embodiments are described herein with the understanding that the embodiments are not intended to limit the invention to the preferred embodiments described and / or illustrated herein. It is not limited to the embodiment described here. The present invention also encompasses any embodiment that includes equivalent elements, modifications, deletions, combinations, improvements and / or changes that may be recognized by those skilled in the art based on this disclosure. Claim limitations should be construed broadly based on the terms used in the claims and should not be limited to the embodiments described herein or in the process of this application. The present invention should be construed broadly based on the terms used in the claims.

DESCRIPTION OF SYMBOLS 1 Vehicle 3a, 3b Wheel 4 Battery 5 Main switch 10 Engine 15 Crankshaft 20 Starter generator 30 Rotor 37a Magnetic pole part 40 Stator 43 Tooth part 60 Control apparatus 61 Inverters 611-616 Switching part

Claims (7)

A vehicle,
The vehicle is
An acceleration instruction unit for instructing acceleration of the vehicle;
An engine configured to output rotational power generated by a combustion operation, the crankshaft outputting the rotational power to the outside of the engine, and an engine output adjusting unit configured to adjust the rotational power An engine having
A drive member that drives the vehicle by receiving rotational power output from the engine via the crankshaft;
A rotor connected to the crankshaft for rotation at a fixed speed ratio with respect to the crankshaft; the crankshaft is driven when the engine is started; and the engine is operated when the engine is combusted A starter generator, which is a three-phase brushless motor, driven by
A battery for transferring current to the starter generator;
An inverter that is disposed between the starter generator and the battery and includes a plurality of switching units that adjust a current flowing between the starter generator and the battery;
When acceleration of the vehicle is instructed by the acceleration instructing unit, the engine output adjusting unit increases rotational power and performs field weakening control on the starting generator with the power of the battery to the starting generator. When the inverter is controlled to drive a crankshaft and the acceleration instruction unit stops the vehicle acceleration instruction, the engine output adjustment unit reduces the rotational power, and the starter generator And a control device for controlling the inverter so as to reduce the driving force of the crankshaft to the starter generator without applying a voltage higher than the voltage of the battery due to the rotation of the crankshaft to the switching unit. . The vehicle of claim 1,
When the acceleration instruction unit stops the acceleration instruction of the vehicle, the control device decreases the rotational power to the engine output adjustment unit and continues the field weakening control on the starter generator while continuing the field weakening control. The inverter is controlled so that an overvoltage higher than the voltage of the battery due to rotation of the crankshaft is not applied from the starter generator to the plurality of switching units by reducing the driving force of the crankshaft. The vehicle according to claim 2,
At least in the case where acceleration of the vehicle is instructed by the acceleration instruction unit and in the case where the instruction of acceleration of the vehicle is stopped, the control device performs the field generation control while performing field weakening control on the starter generator. When the crankshaft is driven by the power of the battery in the machine, the starter / generator is set so that the maximum drive speed at which the crankshaft can be rotated is larger than the actual rotation speed of the crankshaft. On the other hand, field weakening control is performed. The vehicle according to claim 2 or 3,
The control device weakens the field-weakening control in accordance with the decrease in the rotation speed of the crankshaft when the acceleration instruction unit stops the acceleration instruction of the vehicle. The vehicle of claim 1,
When the acceleration instruction unit stops the acceleration instruction of the vehicle, the control device reduces the rotational power to the engine output adjustment unit and short-circuits each phase of the starter generator. Further, the inverter is controlled such that a voltage resulting from rotation of the crankshaft higher than the battery voltage is not applied from the starter generator to the plurality of switching units by reducing the driving force of the crankshaft. A vehicle according to any one of claims 1 to 5,
At least the maximum drive torque that allows the starter generator to drive the crankshaft with the power of the battery when the actual rotational speed of the crankshaft does not perform field weakening control on the starter generator, and When the rotational power of the engine is greater than the rotational speed of the crankshaft at which the torque for rotating the crankshaft is equal, the control device, when the acceleration instruction unit stops the acceleration instruction of the vehicle, The rotating power is reduced in the output adjustment unit, and the crankshaft of the crankshaft is applied to the starter generator so that a voltage caused by rotation of the crankshaft higher than the battery voltage is not applied to the plurality of switching units from the starter generator. Reduce driving force. The vehicle according to any one of claims 1 to 6,
The starting generator is
A stator core having a plurality of teeth provided with slots in the circumferential direction and a winding wound around the teeth, all of the plurality of teeth having a portion around which the winding is wound. The stator,
And a rotor having a permanent magnet portion and a plurality of magnetic pole portions formed by the permanent magnet portion and provided on a surface facing the stator, the number of which is greater than the number of the plurality of teeth.

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