Straddled vehicle

Abstract

The purpose of the present invention is to provide a straddled vehicle provided with a high-voltage hybrid system which is small in size and is lightweight, and can cope with a rotational speed range of a straddled vehicle engine. This straddled vehicle is provided with an engine, a drive wheel, a high-voltage power-supply system, a permanent magnet type motor generator, and a high-voltage power storage device. An MG control device performs, on the permanent magnet type motor generator having a rotor which rotates at the same speed as the engine of the straddled vehicle and in which the number of magnetic poles in the permanent magnet type motor generator is more than 2 / 3 of the number of teeth, a field-weakening control of setting, as a power supply, a high voltage that is higher than a low voltage of a low voltage battery, so as to supply, to a winding, a current component of the field-weakening control through overcoming of the reluctance that increases in a high rotation range of the engine in the straddled vehicle, by the field-weakening control of setting the high voltage as the power supply while increasing the amount of voltage suppression caused by the field-weakening control due to an increase in the reluctance resulting from an increase in the magnetic poles.

Description

Straddled Vehicle

[0001] The present invention relates to a straddled vehicle.

[0002] For example, Patent Document 1 discloses a vehicle equipped with a motor generator connected to an engine. The vehicle shown in Patent Document 1 is an automobile (see FIG. 2 of Patent Document 1). The motor generator is connected to a high-voltage battery via an inverter.

[0003] Patent Document 2 also shows a vehicle equipped with a motor generator. The motor generator shown in Patent Document 2 is connected to an engine via a reduction mechanism such as a belt or chain. The motor generator is supplied with high-voltage electric power from a power storage device. The electric power generated by the motor generator is also supplied to the power storage device at high voltage.

[0004] For example, Patent Document 3 discloses a saddle-ride type vehicle. The saddle-ride type vehicle disclosed in Patent Document 3 includes an engine, a starter-generator, a battery, and a control device. The battery is a low-voltage battery that drives the starter-generator. The control device disclosed in Patent Document 3 performs field-weakening control of the starter-generator so as not to apply a voltage higher than the battery voltage to the low-voltage battery.

[0005] Japanese Patent Laid-Open No. 9-084210 Japanese Patent Laid-Open No. 2005-180254 Japanese Patent Laid-Open No. 2017-129065

[0006] In some cases, it is desirable for a saddle-type vehicle to have a high-voltage hybrid system that is small, lightweight, and compatible with the rotational speed range of the engine of the saddle-type vehicle.

[0007] An object of the present invention is to provide a saddle-type vehicle equipped with a high-voltage hybrid system that is small, lightweight, and compatible with the rotational speed range of the engine of the saddle-type vehicle.

[0008] A straddle-type vehicle is configured so that the vehicle's posture is controlled by the driver's weight shift while driving. Therefore, from the standpoint of operability and driving performance, there is a trend toward straddle-type vehicles being required to be small and lightweight. Accordingly, there is a trend toward hybrid systems and their components being mounted on straddle-type vehicles being small and lightweight.

[0009] A motor generator capable of handling high voltages has a structure that allows it to generate the required power even at low rotation speeds, such as the engine's idle speed. For example, a motor generator capable of handling high voltages has a stronger magnet that generates a higher induced electromotive force than a motor generator that does not handle high voltages.

[0010] For example, it is conceivable to apply the motor generator of an automobile capable of handling high voltages, as disclosed in Patent Documents 1 and 2, to a straddle-type vehicle.

[0011] However, saddle-type vehicle engines tend to operate over a wider range of rotational speeds, including higher rotational speeds, than automobile engines. This is because, while automobile engines are designed to output large torque at low rotational speeds in order to start and accelerate heavy automobiles, saddle-type vehicle engines are designed to start and accelerate relatively light saddle-type vehicles, and are therefore required to be small and lightweight in order to be installed in small and lightweight saddle-type vehicles.

[0012] When a motor generator capable of handling high voltages is driven by a saddle-ride vehicle engine that operates over a wide rotational speed range, the induced electromotive force of the motor generator may become excessive at high rotational speeds of the saddle-ride vehicle engine, causing the terminal voltage of the motor generator to exceed the range that can be controlled by the control device. For example, when the terminal voltage of the motor generator exceeds the controllable range, it is necessary to stop the control of power generation. Furthermore, when power is supplied from a battery to the motor generator to assist the rotation of the engine, the induced electromotive force that counteracts the battery voltage may become excessive, potentially hindering the control of power running by the motor generator.

[0013] In order to suppress the voltage of the motor generator, it is conceivable to connect the engine of the saddle-ride type vehicle to the motor generator via a reduction mechanism such as a belt or chain as shown in Patent Document 2. However, providing a reduction mechanism for the motor generator increases the size and weight of the hybrid system of the saddle-ride type vehicle.

[0014] The inventors conducted extensive research into a compact, lightweight motor generator that can accommodate the rotational speed range of the engine of a saddle-ride type vehicle. As a result, they discovered a configuration that uses a high voltage as a power source to perform field-weakening control on a permanent magnet motor generator that rotates at the same speed as the engine of the saddle-ride type vehicle and has magnetic poles with more than two-thirds the number of teeth. The high voltage is higher than the low voltage of the low-voltage battery.

[0015] When the number of magnetic poles in a permanent magnet motor generator is large, the angular velocity in electrical angle is large. This large reluctance increases the amount of voltage suppression by field-weakening control. On the other hand, when the number of magnetic poles is large, the angular velocity increases even more at high rotational speeds of the engine of a saddle-ride vehicle. The reluctance, which increases with increasing angular speed, is an impedance component, and the impedance, which increases at high rotational speeds, opposes the current component of field-weakening control. However, by using a high-voltage power source, the current can be controlled to the field-weakening target, regardless of the large impedance at high rotational speeds caused by the large number of magnetic poles. In other words, by using a high-voltage power source for field-weakening control, the current component of field-weakening control overcomes the increased impedance at high rotational speeds and is supplied to the winding.

[0016] More specifically, the induced electromotive force E in the winding of a permanent magnet motor generator depends mainly on the product φ·ω of the magnetic flux φ interlinked with the winding and the angular velocity ω in electrical angle. In contrast, the main effective component for generating a terminal voltage suppressed from the induced electromotive force by field-weakening control (also simply referred to as "suppressing the induced electromotive force") is expressed as L·ω·Id. L·ω is the reluctance of the winding. L is the inductance, and is usually a fixed value that depends on the structure of the winding, etc. Id is the field-weakening current generated by field-weakening control, and the magnitude of the field-weakening current Id is controlled by a control device. Angular velocity ω is the speed based on the period in which a pair of magnetic poles passes near a certain tooth. Angular velocity ω can be expressed, for example, by the following equation: ω = (P / 2) × (N rpm / 60) × 2π (P: number of magnetic poles, N: crankshaft rotation speed) At high rotation speeds of a saddle-type vehicle engine, a high induced electromotive force E is generated in the winding due to an increase in φ and ω. Note that when the number of magnetic poles is more than two-thirds the number of teeth, the induced electromotive force E appears to increase in proportion to the increase in angular velocity ω. However, if the number of magnetic poles is increased to more than two-thirds the number of teeth while maintaining the size and weight of the permanent magnet motor generator, the physical size of each magnetic pole becomes smaller, and the magnetic flux φ in the winding decreases accordingly. In other words, the decrease in magnetic flux φ changes in a direction that offsets the increase in angular velocity ω. For this reason, the change in induced electromotive force E caused by increasing the number of magnetic poles is suppressed.

[0017] Field-weakening control by a control device can suppress induced electromotive force that increases in the high rotation range. When the number of magnetic poles is more than two-thirds of the number of teeth, the angular velocity ω of the component L·ω·Id suppressed by field-weakening control is larger than when the number of magnetic poles is two-thirds or less of the number of teeth. Therefore, in a permanent magnet motor generator in which the number of magnetic poles is more than two-thirds of the number of teeth, the amount of suppression of induced electromotive force by field-weakening control is large.

[0018] The reluctance L·ω of the winding, together with pure resistance, constitutes the internal impedance Z of the winding. The impedance Z is an element that resists the winding current. The field-weakening current Id is a component of the current controlled by the control device. The field-weakening current Id also flows against the impedance Z of the winding. As described above, the reluctance that constitutes the impedance of the winding is L·ω, and an increase in angular velocity ω increases the reluctance component, which appears as an increase in impedance. The control device performs control, for example, by the duty ratio of the on-time, so that the field-weakening current Id reaches a target value regardless of changes in impedance Z. However, if the impedance Z increases and exceeds a controllable range, such as the upper limit of the duty ratio, the field-weakening current Id cannot maintain the required target value. The control device of the present disclosure performs field-weakening control using a high voltage power source, and can control the field-weakening current Id to reach the target value by overcoming the large impedance Z caused by the large reluctance L·ω. That is, regardless of the reluctance L·ω that increases when the number of magnetic poles is more than two-thirds the number of teeth, the field weakening current Id can be maintained at the target value even in the high rotation speed range of the engine of the saddle-ride type vehicle.

[0019] In this way, by performing field-weakening control on a permanent magnet motor generator having more than two-thirds the number of teeth using a high voltage as a power source, a synergistic effect is achieved in which greater voltage suppression by field-weakening control can be achieved at higher engine speeds. Due to the synergistic effect of greater voltage suppression by field-weakening control at higher engine speeds, the high-voltage permanent magnet motor generator can suppress fluctuations in terminal output voltage over a wide rotational speed range, from low to high, of the saddle-ride vehicle engine. This suppresses changes in the voltage supplied from the permanent magnet motor generator to the high-voltage power supply system via the control device in response to changes in rotational speed. Furthermore, over a wide rotational speed range, from low to high, of the saddle-ride vehicle engine, power can be supplied from the battery to the motor generator, overcoming induced voltage, allowing power running control by the motor generator. Therefore, a high voltage with reduced fluctuations can be supplied over a wide rotational speed range of the saddle-ride vehicle engine without providing the engine with a reduction mechanism such as a belt or chain, and the engine can be assisted by the motor generator over a wide rotational speed range of the saddle-ride vehicle engine using the power of the high-voltage storage device.

[0020] Patent Document 3 discloses an example of field-weakening control of a motor-generator having a rotor fixed to a crankshaft and magnetic poles with 4 / 3 the number of slots. However, Patent Document 3 uses a control device to control the starter-generator so as not to apply a voltage higher than the battery voltage of the low-voltage battery. In contrast, the technology disclosed herein reverses the concept of Patent Document 3, which controls the starter-generator so as not to apply a voltage higher than the battery voltage of the low-voltage battery. By using a high voltage higher than the low-voltage battery as a power source, field-weakening control is performed on a permanent magnet motor-generator having magnetic poles with more than two-thirds the number of teeth. This allows the field-weakening current Id to be maintained even at high rotation speeds, regardless of the reluctance L·ω that increases when the number of magnetic poles is greater than two-thirds the number of teeth. In other words, the effect of large field-weakening control due to a large angular velocity ω can be exerted over a wide rotation speed range of the saddle-ride vehicle engine, regardless of the large angular velocity ω.

[0021] According to the technology disclosed herein, the field-weakening control provides a synergistic effect of greater voltage suppression at higher engine speeds, thereby suppressing voltage fluctuations over a wide range of engine speeds, including the high engine speed range of a saddle-ride type vehicle, and enabling engine assist control by the motor generator. Therefore, according to the technology disclosed herein, a high-voltage hybrid system can be realized that is small, lightweight, and compatible with the engine speed range of a saddle-ride type vehicle.

[0022] In order to achieve the above object, according to one aspect of the present invention, a vehicle has the following configuration.

[0023] (1) A saddle-ride type vehicle comprising: an engine having a crankshaft and outputting torque via the crankshaft; drive wheels to which at least a portion of the torque output from the engine is mechanically transmitted and which drive the saddle-ride type vehicle; a high-voltage power supply system operating at a high voltage higher than the low voltage of a low-voltage power supply system connected to a low-voltage battery; a permanent magnet motor generator including a stator having a plurality of teeth arranged in the circumferential direction and windings wound on each of the plurality of teeth, and a rotor having magnetic poles provided on a rotating shaft that is coaxial with and rotates at the same speed as the crankshaft, and which applies torque to the drive wheels by powering while receiving and sending power to and from the high-voltage power supply system, and which generates electricity by receiving torque from the engine or the drive wheels; an MG control device electrically connected to the high-voltage power supply system and electrically connected to the permanent magnet motor generator, and which controls the powering and power generation of the permanent magnet motor generator; and a high-voltage electricity storage device electrically connected to the high-voltage power supply system and which charges and discharges at the high voltage higher than the low voltage, wherein the MG control device The field weakening control is performed on the permanent magnet motor generator, which rotates at the same speed as the engine of the saddle-ride type vehicle and has a rotor with magnetic poles that number more than two-thirds of the number of teeth, using the high voltage that is higher than the low voltage of the low-voltage battery as a power source, so that the amount of voltage suppression by the field weakening control is increased due to the increase in reluctance caused by the increase in magnetic poles of the permanent magnet motor generator, and the current component of the field weakening control is supplied to the windings by overcoming the reluctance that increases in the high rotation speed range of the engine of the saddle-ride type vehicle through the field weakening control using the high voltage as a power source.

[0024] The saddle-ride type vehicle (1) includes an engine, drive wheels, a high-voltage power supply system, a permanent magnet motor generator, a high-voltage power storage device, and an MG control device. The engine has a crankshaft. The engine outputs torque via the crankshaft. The drive wheels drive the saddle-ride type vehicle. At least a portion of the torque output from the engine is mechanically transmitted to the drive wheels. The high-voltage power supply system operates at a high voltage. The high voltage is higher than the low voltage of a low-voltage power supply system to which a low-voltage battery is connected. The battery is a secondary battery. The permanent magnet motor generator includes a stator and a rotor. The stator has a plurality of teeth and a winding. The plurality of teeth are arranged circumferentially. A winding is wound around each of the plurality of teeth. The rotor is provided on a rotating shaft that is coaxial with the crankshaft and rotates at the same speed. The rotor has magnetic poles. The permanent magnet motor generator exchanges power with the high-voltage power supply system. The permanent magnet motor generator applies torque to the drive wheels by powering. The permanent magnet motor generator receives torque from the engine or the drive wheels and generates electricity. The MG control device is electrically connected to a high-voltage power supply system. The MG control device is also electrically connected to the permanent magnet motor generator. The MG control device controls the powering and power generation of the permanent magnet motor generator. The saddle-ride type vehicle is a hybrid vehicle. The engine, drive wheels, high-voltage power supply system, permanent magnet motor generator, and MG control device are included in the high-voltage hybrid system of the saddle-ride type vehicle. The saddle-ride type vehicle is also equipped with a high-voltage storage device. The high-voltage storage device is electrically connected to the high-voltage power supply system. The high-voltage storage device charges and discharges at a high voltage that is higher than a low voltage.

[0025] Saddle-ride type vehicles are configured so that the vehicle's posture is controlled in accordance with the driver's weight shift while driving. Therefore, from the standpoints of operability and driving performance, saddle-ride type vehicles tend to be small and lightweight. Accordingly, hybrid systems and their components mounted on saddle-ride type vehicles also tend to be small and lightweight. Furthermore, when a motor generator configured to handle high voltages is driven by a saddle-ride type vehicle engine that operates over a wide rotational speed range, the induced electromotive force of the motor generator may become excessively large at high rotational speeds of the saddle-ride type vehicle engine, potentially causing the terminal voltage of the motor generator to exceed the range controllable by the control device. The MG control device for a saddle-ride type vehicle (1) performs field-weakening control on a permanent magnet motor generator that rotates at the same speed as the saddle-ride type vehicle engine and has a rotor with magnetic poles that number more than two-thirds the number of teeth, using a high voltage that is higher than the low voltage of a low-voltage battery as a power source. As a result, the MG control device increases the amount of voltage suppression by field weakening control due to the increase in reluctance caused by the increase in magnetic poles of the permanent magnet motor generator, and performs field weakening control using a high voltage power source to overcome the increase in reluctance in the high rotation speed range of the engine of the saddle-ride type vehicle and supply the current component of field weakening control to the winding. Here, the increase in reluctance due to the increase in magnetic poles means that there are more magnetic poles than two-thirds the number of teeth.

[0026] Field-weakening control by a control device can suppress induced electromotive force that increases in the high rotation range. When the number of magnetic poles is more than two-thirds of the number of teeth, the angular velocity ω of the suppression component L·ω·Id by field-weakening control is larger than when the number of magnetic poles is two-thirds or less of the number of teeth. Therefore, in a permanent magnet motor generator in which the number of magnetic poles is more than two-thirds of the number of teeth, the amount of suppression of induced electromotive force by field-weakening control is large. Here, L is inductance. Id is the field-weakening current by field-weakening control. ω is the angular velocity in electrical angle. L·ω is the reluctance of the winding.

[0027] The reluctance L·ω of the winding, together with pure resistance, constitutes the internal impedance Z of the winding. The impedance Z is an element that resists the winding current. The field weakening current Id is a component of the current controlled by the control device. The field weakening current Id also flows against the impedance Z of the winding. As described above, the reluctance that constitutes the impedance of the winding is L·ω, and it increases as the angular velocity ω increases. The control device performs control, for example, by the duty ratio of the on-time, so that the field weakening current Id reaches a target value regardless of changes in the impedance Z. However, if the impedance Z increases and exceeds a controllable range, such as the upper limit of the duty ratio, the field weakening current Id cannot maintain the required target value. The control device of the present disclosure performs field weakening control using a high voltage power source, and can control the field weakening current Id to reach the target value by overcoming the large impedance Z caused by the large reluctance L·ω. That is, even if the reluctance L·ω is large because the number of magnetic poles is more than two-thirds the number of teeth, the field weakening current Id can be maintained at the target value in the high rotation speed range of the engine of the saddle-ride type vehicle.

[0028] In this way, by performing field-weakening control on a permanent magnet motor generator having more than two-thirds the number of teeth using a high voltage as a power source, a synergistic effect is achieved in which greater voltage suppression by field-weakening control can be achieved at higher engine speeds. Due to the synergistic effect of greater voltage suppression by field-weakening control at higher engine speeds, the high-voltage permanent magnet motor generator can suppress fluctuations in terminal output voltage over a wide rotational speed range, from low to high, of the saddle-ride vehicle engine. This suppresses changes in the voltage supplied from the permanent magnet motor generator to the high-voltage power supply system via the control device in response to changes in rotational speed. Furthermore, engine assist control by the permanent magnet motor generator can be performed using power from the high-voltage power storage device over a wide rotational speed range of the saddle-ride vehicle engine. Therefore, without providing a reduction mechanism such as a belt or chain to the engine, the high-voltage storage device can be charged with a high voltage with reduced fluctuations over a wide rotational speed range of the saddle-ride type vehicle engine, and the power from the high-voltage storage device can be used to perform engine assist control by the permanent magnet motor generator over a wide rotational speed range of the saddle-ride type vehicle engine.

[0029] In the saddle-ride type vehicle (1), the field-weakening control exerts a greater voltage suppression effect at higher engine speeds, resulting in a synergistic effect that suppresses voltage fluctuations over a wide range of engine speeds, including the high-speed range of the saddle-ride type vehicle's engine, and the permanent magnet motor generator can provide engine assist control over a wide range of engine speeds using power from the high-voltage power storage device. This makes it possible to realize a high-voltage hybrid system that is compact, lightweight, and compatible with the engine's wide speed range of the saddle-ride type vehicle.

[0030] According to one aspect of the present invention, a vehicle can employ the following configuration: (2) The saddle-ride type vehicle of (1), further comprising: a starter motor that operates at the low voltage of the low-voltage power supply system to start the engine without powering the permanent magnet motor generator, and the MG control device performs the field-weakening control on the permanent magnet motor generator that rotates at the same speed as the engine of the saddle-ride type vehicle and has a rotor with magnetic poles that have more than two-thirds the number of teeth, using as a power source the high voltage that is higher than the low voltage of the low-voltage battery that operates the starter motor.

[0031] The saddle-type vehicle (2) includes a starter motor that operates at a low voltage and starts the engine. Therefore, the engine can be started even if the permanent magnet motor generator does not have an engine-starting function. Generally, engine-starting motors output a large torque sufficient to start the engine, so it is often necessary to strengthen the magnetic flux of the magnet. However, omitting the starting function from the permanent magnet motor generator increases structural flexibility, allowing, for example, the use of a weaker magnet compared to a system with a starting function. The MG control device uses a high voltage, which is higher than the low-voltage battery that operates the starter motor, as its power source and performs field-weakening control on the permanent magnet motor generator, which has a rotor with more than two-thirds the number of magnetic poles. Because there is a high degree of design freedom regarding the induced electromotive force at high rotational speeds, which is the target of field-weakening control using a high-voltage power source, a wider rotational speed range of the saddle-type vehicle engine can be accommodated. As a result, a small, lightweight, and high-voltage hybrid system capable of accommodating a wider rotational speed range can be realized.

[0032] According to one aspect of the present invention, the vehicle can employ the following configuration: (3) In the saddle-ride type vehicle of (1) or (2), the high-voltage power storage device is a capacitor or a secondary battery, the permanent magnet motor generator receives electric power from the capacitor to power itself and apply torque to the crankshaft, and the MG control device performs the field-weakening control on the permanent magnet motor generator, which rotates at the same speed as the engine of the saddle-ride type vehicle and has a rotor with magnetic poles that number more than two-thirds of the number of teeth, using the high voltage, which is higher than the low voltage of the low-voltage battery and to which the capacitor or the secondary battery is connected, as a power source.

[0033] The capacitor or secondary battery charges and discharges. The MG control device performs field-weakening control on a permanent magnet motor generator having a rotor with magnetic poles that are more than two-thirds the number of teeth, using the high voltage of the capacitor or secondary battery, which is higher than the low voltage of the low-voltage battery, as a power source. The permanent magnet motor generator supplies power to the capacitor or secondary battery, which charges the capacitor, and the power from the capacitor or secondary battery can be used to perform engine assist control using the permanent magnet motor generator, making it possible to realize a small, lightweight, high-voltage hybrid system that can accommodate a wider range of rotational speeds.

[0034] According to one aspect of the present invention, the vehicle can employ the following configuration: (4) The saddle-ride type vehicle of (3), wherein the secondary battery is a large-current chargeable drive lithium-ion battery that satisfies large-current discharge specifications and large-current charge specifications, the permanent magnet motor generator receives power from the large-current chargeable drive lithium-ion battery and powers it to apply torque to the crankshaft, the large-current discharge specifications meaning a battery specification that allows for discharge at a maximum current during use corresponding to a rate of 10 C or more for a charge capacity of 2.5 Ah, and the large-current charge specifications meaning a battery specification that allows for charging at a maximum current during use corresponding to a rate of 10 C or more for a charge capacity of 2.5 Ah, and the MG control device performs the field-weakening control on the permanent magnet motor generator, which rotates at the same speed as the engine of the saddle-ride type vehicle and has a rotor with magnetic poles that number more than two-thirds of the number of teeth, using the high voltage, which is higher than the low voltage of the low-voltage battery and to which the large-current chargeable drive lithium-ion battery is connected, as a power source.

[0035] According to (4), the secondary battery is a high-current rechargeable lithium-ion battery that meets high-current discharge and high-current charge specifications. The high-current discharge specification is a battery specification that allows the battery to be discharged at a maximum current during use corresponding to a rate of 10 C or more for a charge capacity of 2.5 Ah, and the high-current charge specification is a battery specification that allows the battery to be charged at a maximum current during use corresponding to a rate of 10 C or more for a charge capacity of 2.5 Ah. The high-current rechargeable lithium-ion battery discharges and charges at a high current like a capacitor, so it can be rapidly charged when a permanent magnet motor generator having a rotor with more than two-thirds the number of teeth is generating electricity, and can supply a large current to the permanent magnet motor generator when the permanent magnet motor generator is assisting the engine. The MG control device performs field-weakening control on the permanent magnet motor generator having a rotor with more than two-thirds the number of teeth using a high voltage power source that is higher than the low voltage of the low-voltage battery and is connected to a capacitor or a high-current rechargeable lithium-ion battery. The permanent magnet motor generator supplies power to the capacitor or the high-current chargeable lithium-ion battery, which is then rapidly charged. The large current from the high-current chargeable lithium-ion battery can also be used to control engine assist using the permanent magnet motor generator, making it possible to realize a small, lightweight, high-voltage hybrid system that can provide powerful assistance over a wider range of rotational speeds.

[0036] The terminology used herein is for the purpose of defining particular embodiments only and is not intended to limit the invention. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed components. As used herein, the use of the terms "including," "comprising," or "having," and variations thereof, identifies the presence of stated features, steps, operations, elements, components, and / or equivalents thereof, but may include one or more of the steps, operations, elements, components, and / or groups thereof. As used herein, the terms "attached," "connected," "coupled," and / or equivalents thereof are used broadly and encompass both direct and indirect attachments, connections, and couplings. Furthermore, "connected" and "coupled" are not limited to physical or mechanical connections or couplings, but can include direct or indirect electrical connections or couplings. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms, such as those defined in commonly used dictionaries, should be interpreted to have a meaning consistent with the relevant technology and the context of this disclosure, and should not be interpreted in an idealized or overly formal sense unless explicitly defined herein. It is understood that numerous techniques and processes are disclosed in the description of the present invention. Each of these has distinct advantages, and each can be used with one or more, or in some cases all, of the other disclosed technologies. Therefore, for the sake of clarity, this description will refrain from unnecessarily repeating all possible combinations of individual steps. Nevertheless, the specification and claims should be read with the understanding that all such combinations are within the scope of the present invention and claims. A novel straddle-type vehicle is described herein. In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of the present invention.However, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. The present disclosure is to be considered as an example of the present invention and is not intended to limit the invention to the specific embodiments illustrated by the following drawings or description.

[0037] A straddle-type vehicle or straddled vehicle is a vehicle in which a driver sits astride a saddle. A straddle-type vehicle is configured so that the vehicle's posture is controlled by the driver's weight shift while traveling. Examples of straddle-type vehicles include scooter-type, moped-type, off-road-type, and on-road-type motorcycles. Furthermore, a straddle-type vehicle is not limited to motorcycles, but may also be, for example, a three-wheeled or four-wheeled buggy known as an ATV (All Terrain Vehicle), a snowmobile, or the like. A straddle-type vehicle is, for example, a leaning vehicle that turns in a leaning position. A leaning vehicle leans toward the center of a turn when turning. A leaning vehicle is, for example, a motorcycle or a tricycle. A straddle-type vehicle in the present disclosure is a vehicle driven by the output of an engine. A straddle-type vehicle does not include, for example, a bicycle. A leaning vehicle leans toward the center of a curve through operations including the driver's weight shift. Since the attitude of a saddle-type vehicle is controlled by the driver, it is preferable that the saddle-type vehicle be as small and light as possible.

[0038] The engine is an internal combustion engine. The engine may be, for example, a single-cylinder engine or an engine with multiple cylinders. The engine may be, for example, a four-stroke engine or a two-stroke engine. The saddle-ride type vehicle engine is an engine mounted on the saddle-ride type vehicle.

[0039] A drive wheel is a wheel that drives a saddle-riding vehicle. A saddle-riding vehicle may also have wheels other than drive wheels. A saddle-riding vehicle may have, for example, front wheels and rear wheels. In this case, the drive wheels may be rear wheels, front wheels, or both front and rear wheels.

[0040] The high-voltage power supply system is a system that transmits a high voltage. The high voltage is a voltage higher than the low voltage of the low-voltage power supply system. When a saddle-ride type vehicle has a system that transmits a high voltage and a system that transmits a low voltage, the system that transmits the high voltage is the high-voltage power supply system. The high voltage in the high-voltage power supply system means the voltage when at least the engine is in combustion operation. When the engine is stopped, the voltage in the high-voltage power supply system may be a low voltage including zero. The high voltage in a saddle-ride type vehicle is, for example, a voltage exceeding 24 V. In this case, the low voltage is a voltage equal to or less than 24 V. The high voltage may be, for example, a voltage exceeding 12 V. In this case, the low voltage is a voltage equal to or less than 12 V. If the high voltage in a saddle-type vehicle does not exceed, for example, 60 V, the saddle-type vehicle operates within the "extra low voltage (ELV)" or "safety extra low voltage (SELV)" range defined in the IEC 60950 standard of the International Electrotechnical Commission (IEC). In this case, the level of insulation in the power supply system is sufficient within the "operational insulation" range, allowing the wiring area to be reduced in size. However, the high voltage in a saddle-type vehicle is not particularly limited and may be, for example, 60 V or higher.

[0041] Secondary batteries and capacitors are devices that charge and discharge. Secondary batteries are storage batteries. Secondary batteries charge and discharge through chemical reactions at the electrodes. Secondary batteries charge and discharge through oxidation and reduction reactions at the electrodes. Secondary batteries store charged power as chemical energy. Secondary batteries convert stored chemical energy into electrical energy. Capacitors charge and discharge without chemical reactions at the electrodes. Capacitors store supplied power as electric charge. A high-current rechargeable lithium-ion battery is, for example, a secondary battery having a negative electrode containing at least one selected from the group consisting of spinel-type lithium titanate, niobium-titanium-containing composite oxide, and graphite. The rate of a battery represents the speed at which electric charge is accumulated or released. The unit is C. The high-current charge specification corresponds to the maximum charge rate allowed when charging. The high-current discharge specification corresponds to the maximum charge rate allowed when discharging. The current corresponding to the maximum charge rate is the maximum operating current. The magnitude of the current that fully charges the battery capacity in 1 hour is defined as 1 C. For example, if the battery capacity is 2.5 Ah, 1 C is 2.5 A.

[0042] The high-voltage power supply system may be electrically connected to a device other than the high-voltage power storage device. For example, the high-voltage power supply system may be connected to a second motor generator, an electric turbocharger, or an electric supercharger provided in a torque transmission path between the engine and the drive wheels. The high-voltage power supply system may be connected to a high-voltage load that operates at a high voltage.

[0043] A permanent magnet motor generator is a rotating electric machine that combines the functions of a motor and a generator. A permanent magnet motor generator generates a magnetic field using permanent magnets. This does not include induction machines or alternators, which generate a magnetic field using electromagnets. A permanent magnet motor generator is, for example, an outer rotor type. However, the permanent magnet motor generator is not particularly limited and may be, for example, an inner rotor type. A permanent magnet motor generator is, for example, a surface permanent magnet motor (SPM). However, the permanent magnet motor generator is not particularly limited and may be, for example, an interior permanent magnet motor (IPM). A permanent magnet motor generator having magnetic poles that are more than two-thirds the number of teeth is, for example, a permanent magnet motor generator having magnetic poles that are equal to or greater than four-thirds the number of teeth. Such a permanent magnet motor generator is, for example, a permanent magnet motor generator having magnetic poles that are equal to or greater than four-thirds the number of teeth. However, the relationship between the number of teeth and the number of magnetic poles of a permanent magnet motor generator is not particularly limited as long as the number of magnetic poles is greater than two-thirds the number of teeth. Examples of such relationships include configurations in which the number of magnetic poles is 5 / 6, 8 / 9, 11 / 12, 13 / 12, and 14 / 12 relative to the number of teeth. When the number of magnetic poles is greater than two-thirds of the number of teeth, the angular velocity ω increases, resulting in a large reluctance at high rotation speeds. This effectively suppresses voltage fluctuations through field-weakening control. For example, when the number of magnetic poles is a multiple of two, such as when the number of magnetic poles is four-thirds of the number of teeth, circumferentially aligned magnetic pole pairs are easily formed. Furthermore, when the number of teeth is a multiple of three, the permanent magnet motor generator can operate with high efficiency using a three-phase drive current. When the number of magnetic poles is four-thirds or less of the number of teeth, sufficient magnetic flux density can be maintained in each magnetic pole while maintaining the size and weight of the permanent magnet motor generator.

[0044] The rotating shaft on which the rotor is provided, i.e., the rotating shaft that rotates coaxially with and at the same speed as the crankshaft, is, for example, the crankshaft itself. In this case, the rotor is provided on a part of the crankshaft. However, the rotating shaft is not particularly limited and may be, for example, a rotating shaft that is separate from the crankshaft, arranged coaxially with the crankshaft, and connected to the crankshaft by a connecting member such as a connecting sleeve. However, for example, a shaft connected to the crankshaft via a planetary gear does not rotate at the same speed as the crankshaft, and therefore does not fall under the category of a rotating shaft that is coaxial with and rotates at the same speed as the crankshaft.

[0045] The MG control device includes, for example, a processor that executes a program and a memory that stores the program and data. The control device is realized, for example, by the processor executing a program stored in the memory. However, the structure of the control device is not particularly limited, and may be, for example, a logic circuit that processes data without relying on a processor or a program. The MG control device may also have, for example, a function to control the engine. However, the MG control device is not particularly limited, and may be, for example, a separate entity from the control device that controls the engine.

[0046] Field-weakening control is a method of controlling the current in a winding so that a component of current that weakens the field generated by the permanent magnet of the motor generator flows through the winding. The component of current that weakens the field corresponds to the d-axis component of the q-axis and d-axis components in a vector control method. However, the control method is not particularly limited, and any method may be used as long as the component of current that weakens the field flows through the winding as a result of the control. The control method may be, for example, phase control, in which the d-axis component is not explicitly processed and the phase of the current is directly controlled relative to the phase of the electrical angle.

[0047] According to the present invention, it is possible to provide a saddle-type vehicle equipped with a high-voltage hybrid system that is small and lightweight and can accommodate the rotational speed range of the engine of the saddle-type vehicle.

[0048] 1 is a diagram illustrating a saddle-ride type vehicle according to a first embodiment. FIG. 2 is a chart illustrating an outline of the operation of field-weakening control in the permanent magnet motor generator shown in FIG. 1. FIG. 3 is a block diagram illustrating a second embodiment of the high-voltage hybrid system according to the present invention.

[0049] Hereinafter, a saddle-type vehicle according to an embodiment will be described with reference to the drawings. Note that the embodiment described below is merely an example. The present invention should not be construed as being limited in any way by the embodiment described below.

[0050] [First Embodiment] Fig. 1 is a diagram illustrating a saddle-ride type vehicle according to a first embodiment. Part (a) of Fig. 1 is a schematic side view of the saddle-ride type vehicle. Part (b) of Fig. 1 is a block diagram illustrating a schematic configuration of a high-voltage hybrid system for a saddle-ride type vehicle. Part (c) of Fig. 1 is a side view showing a detailed configuration example of the permanent magnet motor generator shown in part (b) of Fig. 1. Part (d) of Fig. 1 is a block diagram showing an equivalent circuit of windings in a permanent magnet motor generator. Part (e) of Fig. 1 is a vector diagram illustrating the operation of field-weakening control. Part (f) of Fig. 1 is a graph showing reluctance characteristics versus rotational speed. Part (g) of Fig. 1 is a graph showing field-weakening current characteristics versus rotational speed.

[0051] The straddle-type vehicle 10 shown in FIG. 1 includes an engine (EG) 11 , drive wheels 12 a , a high-voltage power supply system 13 , a permanent magnet motor generator 14 , and an MG control unit (MGCU) 15 .

[0052] The engine 11 has a crankshaft 11a. The engine 11 generates power by combusting an air-fuel mixture containing air and fuel. The engine 11 outputs power as rotational torque. The engine 11 outputs torque via the crankshaft 11a. The drive wheels 12a drive the saddle-riding vehicle 10. The saddle-riding vehicle 10 has multiple wheels 12a, 12b. The wheel 12a functions as the drive wheel 12a. At least a portion of the torque output from the engine 11 is mechanically transmitted to the drive wheel 12a. The high-voltage power supply system 13 supplies electricity at a high voltage Vhigh that is higher than the low voltage Vlow of the low-voltage power supply system 17. No battery is connected to the high-voltage power supply system 13. The saddle-riding vehicle 10 does not have a battery that operates at the high voltage Vhigh. In the example shown in the figure, the low-voltage power supply system 17 is connected to the high-voltage power supply system 13 via a DC-DC converter 18. The high voltage Vhigh of the high-voltage power supply system 13 is converted to a low voltage Vlow by a DC-DC converter 18 and supplied to a low-voltage power supply system 17. A low-voltage device 19 that operates on the low voltage Vlow is connected to the low-voltage power supply system 17. A low-voltage battery 22 that operates on the low voltage Vlow is also connected to the low-voltage power supply system 17.

[0053] The permanent magnet motor generator 14 is electrically connected to the high-voltage power supply system 13. More specifically, the permanent magnet motor generator 14 is electrically connected to the high-voltage power supply system 13 via an MG control unit (MGCU) 15. The permanent magnet motor generator 14 applies torque to the drive wheels 12a by powering. More specifically, the permanent magnet motor generator 14 applies torque to the crankshaft 11a by powering. For example, the permanent magnet motor generator 14 assists the engine 11 in traveling by powering. The permanent magnet motor generator 14 also receives torque from the engine 11 or the drive wheels 12a to generate electricity. The MG control unit 15 controls the powering and power generation of the permanent magnet motor generator 14. The saddle-ride type vehicle 10 is a hybrid vehicle. The saddle-ride type vehicle 10 is equipped with a high-voltage hybrid system HV. The engine 11 , drive wheels 12 a , high-voltage power supply system 13 , permanent magnet motor generator 14 , and MG control device 15 are included in a high-voltage hybrid system HV of the saddle-ride type vehicle 10 .

[0054] The straddle-type vehicle 10 further includes a high-voltage storage device 16. The high-voltage storage device 16 is electrically connected to the high-voltage power supply system 13. The high-voltage storage device 16 charges and discharges at a high voltage that is higher than the low voltage. In this embodiment, the high-voltage storage device 16 is, for example, a capacitor or a secondary battery. For example, a high-current rechargeable drive lithium-ion battery that meets high-current discharge and high-current charge specifications can be used as the secondary battery. The high-current discharge specification refers to a battery specification that allows for discharge at a maximum current during use corresponding to a rate of 10 C or higher for a charge capacity of 2.5 Ah. The high-current charge specification refers to a battery specification that allows for charging at a maximum current during use corresponding to a rate of 10 C or higher for a charge capacity of 2.5 Ah. The high-current rechargeable drive lithium-ion battery discharges and charges at a high current like a capacitor, allowing for rapid charging and output of a large current. The high-current rechargeable drive lithium-ion battery can have a negative electrode that contains, for example, spinel-type lithium titanate, a niobium-titanium-containing composite oxide, or graphite.

[0055] As shown in part (c) of Fig. 1, the permanent magnet motor generator 14 in the saddle-ride type vehicle 10 includes a stator 141 and a rotor 142. The stator 141 has a plurality of teeth 141T arranged in the circumferential direction, i.e., the rotational direction of the rotor 142, and windings 141W wound around each of the plurality of teeth 141T. More specifically, the plurality of teeth 141T are arranged so as to be separated by slots 141S.

[0056] The rotor 142 is provided on a rotating shaft that is coaxial with and rotates at the same speed as the crankshaft 11a. In this embodiment, the rotating shaft that is coaxial with and rotates at the same speed as the crankshaft 11a is the crankshaft 11a. The rotor 142 is mechanically connected to an end of the crankshaft 11a. In other words, the permanent magnet motor generator 14 is connected to an end of the crankshaft 11a. The rotor 142 has magnetic poles 142a that are greater than two-thirds the number of teeth 141T. In this embodiment, the rotor 142 has magnetic poles 142a that are four-thirds the number of teeth 141T. The magnetic poles 142a are arranged side by side in the rotational direction. The magnetic poles 142a are made of permanent magnets. In the example shown in the figure, a structure is shown in which the same number of permanent magnets as the magnetic poles 142a are arranged circumferentially. However, the structure of the magnetic poles 142a is not particularly limited, and may be, for example, a structure magnetized so that multiple magnetic poles 142a are generated in one cylindrical permanent magnet, or a structure magnetized so that multiple magnetic poles 142a are generated in each of a permanent magnet shaped like a cylinder divided into two or three blocks.

[0057] The permanent magnet motor generator 14 is electrically connected to a permanent magnet turbo motor generator 161, which is an electric power exchange device, via an MG control device 15. The MG control device 15 performs power running and power generation control, including field weakening control. The permanent magnet motor generator 14 exchanges electric power with the permanent magnet turbo motor generator 161 via the MG control device 15 without going through a battery.

[0058] In a permanent magnet motor-generator 14 having magnetic poles 142a that are more than two-thirds the number of teeth 141T, the angular velocity ω in electrical angle is greater than the mechanical rotational speed of the rotor 142, compared to, for example, a case in which the number of magnetic poles 142a is two-thirds or less of the number of teeth 141T. The mechanical rotational speed is the number of rotations per unit time of the rotor 142. In contrast, the angular velocity in electrical angle is the rotation angle based on the repetition period of a pair of magnetic poles 142a passing near one tooth 141T.

[0059] The MG control device 15 performs field weakening control on the permanent magnet motor generator 14, which rotates at the same speed as the engine 11 of the saddle-ride type vehicle 10 and has a rotor 142 with magnetic poles 142a that are more than two-thirds the number of teeth 141T, using a high voltage Vhigh that is higher than the low voltage of the low-voltage battery 22 as a power source. As a result, the MG control device 15 increases the amount of voltage suppression by field weakening control due to an increase in reluctance Lω caused by an increase in the magnetic poles 142a of the permanent magnet motor generator 14, and performs field weakening control using the high voltage Vhigh as a power source so as to overcome the reluctance Lω that increases in the high rotation speed range of the engine 11 of the saddle-ride type vehicle 10 and supply a current component of the field weakening control to the winding 141W.

[0060] As shown in the equivalent circuit of part (d) of FIG. 1 , the winding 141W electrically includes an AC voltage source 141A, an inductor 141B, and a resistor 141R. The induced voltage E output by the AC voltage source 141A depends on the angular velocity ω. More specifically, the induced voltage E depends on the product of the angular velocity ω and the magnetic flux φ mainly interlinking with the winding 141W. The inductance L of the inductor 141B mainly depends on the magnetic flux interlinking with the winding 141W. The product L·ω of the angular velocity ω and the inductance L is the reluctance of the winding 141W. The reluctance is expressed as L·ω or Lω. The resistance value R of the resistor 141R is the winding resistance. The impedance Z of the winding 141W is roughly expressed as ((Lω)^2 + R^2)^1 / 2.

[0061] In the vector diagram of part (e) of Fig. 1, Vhigh represents the magnitude of the high voltage of the high-voltage power supply system 13. E represents the induced electromotive force. Id represents the d-axis current component, which is the field-weakening current. Iq represents the q-axis current component.

[0062] The induced voltage E depends on the product of the angular velocity ω and the magnetic flux φ interlinked mainly with the winding 141W, and therefore increases as the mechanical rotation speed of the permanent magnet motor-generator 14 increases. The voltage output from the permanent magnet motor-generator 14, i.e., the terminal voltage, is the result of the induced voltage E being affected by the current flowing through the winding 141W, i.e., the current flowing through the inductor 141B and the resistor 141R. The current flowing through the winding 141W includes a field-weakening current Id component. The field-weakening current Id generates a magnetic flux oriented along the magnetic flux generated by the magnetic pole 142a and is also referred to as the d-axis current Id. In contrast, the q-axis current Iq generates a magnetic flux perpendicular to the field-weakening current Id in the vector diagram. The q-axis current generates a magnetic flux perpendicular to the magnetic flux generated by the magnetic pole 142a and is a current for directly controlling the torque of the permanent magnet motor-generator 14. The induced electromotive force E is suppressed by the voltage drops Iq·R and Iq·Lω caused by the q-axis current Iq, and the voltage drops Id·R and Id·Lω caused by the field-weakening current Id. The q-axis current Iq is a main factor in generating torque of, for example, the permanent magnet motor-generator 14, and varies depending on the state of the high-voltage power storage device 16 and the torque of the permanent magnet motor-generator 14. For example, when the q-axis current Iq is small, depending on the charging / discharging state of the high-voltage power storage device 16, suppression by the q-axis current Iq does not function. Therefore, suppression of the induced electromotive force E in the high rotation speed range is controlled particularly by the field-weakening current (d-axis current) Id, which is controlled by the field-weakening control of the MG control device 15. In particular, the induced electromotive force E is suppressed by Id·Lω.

[0063] In a permanent magnet motor generator 14 having magnetic poles 142a that are more than two-thirds the number of teeth 141T, the angular velocity ω in electrical angle relative to the mechanical rotational speed of the rotor 142 is larger than in a case where the number of magnetic poles is less than two-thirds the number of teeth, for example.

[0064] Part (f) of Fig. 1 shows the reluctance Lω in this embodiment and the reluctance (Lω)' in a comparative example in which the number of magnetic poles is less than two-thirds the number of teeth. As shown in part (f) of Fig. 1, when the number of magnetic poles 142a is more than two-thirds the number of teeth 141T, the reluctance Lω in the suppression component L·ω·Id by field-weakening control is larger than the reluctance (Lω)' when the number of magnetic poles is smaller (Y1 in part (f) of Fig. 1). Therefore, in a permanent magnet motor-generator 14 in which the number of magnetic poles 142a is more than two-thirds the number of teeth 141T, the amount of suppression of terminal voltage by field-weakening control is large.

[0065] Part (g) of FIG. 1 shows the field weakening current Id in this embodiment and, as a comparative example, the field weakening current Id′ when controlled using the low voltage Vlow as a power source, as indicated by dashed lines. The field weakening current Id is a current component controlled by the MG control device 15. The MG control device 15 controls the field weakening current Id to a target value corresponding to the required amount of suppression. The field weakening current Id flows against the impedance Z of the winding 141W. As described above, the reluctance L·ω included in the impedance Z of the winding 141W increases according to the angular velocity ω. Within the controllable range, the control device controls the field weakening current Id to a target value corresponding to the suppression, regardless of changes in the impedance Z. For example, the control device performs control via the duty ratio of the on-time as a current command value.

[0066] For example, as shown by the dashed line in part (g) of FIG. 1, the field-weakening current Id' is controlled to a target value corresponding to the suppression of an increase in the induced electromotive force as the rotation speed N increases. However, once a control command value such as the duty ratio reaches its upper limit in the high rotation speed range, it cannot be increased any further. The current Id'max at the upper limit of the command value is based on the low voltage Vlow, which is the power supply voltage, and the impedance Z. If the rotation speed increases after the command value reaches its upper limit, the impedance Z increases while the command value remains at the upper limit.

[0067] The control device of this embodiment performs field-weakening control using high voltage Vhigh as a power source, thereby increasing the maximum value Idmax of field-weakening current Id that can be flowed by control, for example, as shown by the solid line in part (g) of Fig. 1. Therefore, the field-weakening current Id can be controlled to reach a target value, overcoming a large impedance Z resulting from a larger reluctance L·ω. In other words, even if the number of magnetic poles 142a is greater than two-thirds of the number of teeth 141T, resulting in a large reluctance L·ω, the field-weakening current Id in the high rotation speed range of the engine 11 of the saddle-ride type vehicle 10 can be maintained at the target value (arrow Y2).

[0068] In this way, by performing field-weakening control using a high voltage as a power source on the permanent magnet motor-generator 14, which has more than two-thirds the number of magnetic poles 142a than the number of teeth 141T, greater voltage suppression can be achieved through field-weakening control, and a synergistic effect is achieved in which this voltage suppression can be exerted at higher rotational speeds of the engine 11 (the increase in the arrow Y1 and the increasing rotational speed range). This allows voltage fluctuations to be suppressed over a wide rotational speed range of the engine 11 of the saddle-riding vehicle 10, from low to high rotational speeds. This suppresses changes in the voltage supplied from the permanent magnet motor-generator 14 to the high-voltage power supply system 13 via the MG control device 15 in response to changes in rotational speed. This means that the high-voltage storage device 16 can be charged with a high voltage whose fluctuations are suppressed over a wide rotational speed range of the engine 11 of the saddle-riding vehicle 10, without providing the engine 11 with a speed reduction mechanism such as a belt or chain. Furthermore, the permanent magnet motor-generator 14 can perform assist control of the engine 11 using the power of the high-voltage power storage device 16 over a wide rotational speed range of the engine 11 of the saddle-riding vehicle 10. Therefore, in the saddle-riding vehicle 10 of this embodiment, a synergistic effect is achieved in which greater voltage suppression by the field-weakening control is exerted at higher rotational speeds, making it possible to charge the high-voltage power storage device 16 while suppressing voltage fluctuations over a wide rotational speed range, including the high rotational speed range, of the engine 11 of the saddle-riding vehicle 10, and also making it possible to perform engine assist control by the permanent magnet motor-generator 14 over a wide rotational speed range of the engine 11 of the saddle-riding vehicle 10 using the power of the high-voltage power storage device 16. Therefore, the high-voltage hybrid system HV is small and lightweight, and can be used over the wide rotational speed range of the engine 11 of the saddle-riding vehicle 10.

[0069] The effect of field weakening control using a high voltage as a power source for the permanent magnet motor generator 14, which has magnetic poles 142a more than two-thirds the number of teeth 141T, can be achieved in both power generation and power running.

[0070] Figure 2 is a chart that schematically illustrates the effect of field-weakening control in the permanent magnet motor generator shown in Figure 1. Part (a) of Figure 2 illustrates the maximum output torque characteristics and output power characteristics versus rotational speed during power running. Part (b) of Figure 2 illustrates the output power characteristics versus rotational speed during power generation. The output power of the motor generator during power running is mechanical, and the output power during power generation is electrical. The motor generator is a device that converts mechanical power and electrical power into each other.

[0071] First, with reference to part (a) of FIG. 2, an example of characteristics during power running when the permanent magnet motor generator 14 functions as a motor will be described.

[0072] The MG control device 15 of this embodiment performs field-weakening control. In the field-weakening control, the MG control device 15 passes a current through the winding 141W to generate a magnetic field in the opposite direction to the magnetic field caused by the magnetic pole 142a, which generates the induced electromotive force. This is equivalent to a decrease in the magnetic force of the magnetic pole 142a. As a result, at the maximum output rotation speed NmaxP of the engine 11, a larger current that contributes to torque can be passed through the winding 141W. Note that the maximum output rotation speed NmaxP is the rotation speed at which the maximum output of the engine 11 can be obtained, and is one index representing the dynamic range of the rotation speed of the engine 11. The upper limit rotation speed Na of the engine 11 is even greater than the maximum output rotation speed NmaxP.

[0073] More specifically, the MG control device 15 applies a d-axis current that contributes to the reverse magnetic flux as field-weakening control. The upper right portion of part (a) of Figure 2 shows a voltage vector diagram illustrating the voltage relationship during power running at the maximum output rotation speed NmaxP of the engine 11.

[0074] Through field-weakening control, the magnitude of the voltage Vt at the output switching unit of the MG control device 15 is equal to the magnitude of the high voltage Vhigh of the high-voltage power supply system 13. Specifically, the magnitude of the voltage Vt obtained by combining the induced electromotive force E, the voltage drops Iq·R and Iq·Lω of the q-axis current Iq, and the voltage drops Id·R and Id·Lω of the field-weakening current Id, is equal to the magnitude of the high voltage Vhigh of the high-voltage power supply system 13. Here, R represents the resistance of the winding 141W, and L represents the inductance of the winding 141W. In this case, at the maximum output rotation speed NmaxP, the MG control device 15 can use the voltage of the high-voltage power supply system 13 to enable the permanent magnet motor generator 14 to output torque that rotates the crankshaft 11a. In the example shown in the figure, the permanent magnet motor generator 14 can output power for power running even at a rotation speed Na that exceeds the maximum output rotation speed NmaxP of the engine 11. The number of magnetic poles 142a in the permanent magnet motor generator 14 is more than two-thirds the number of teeth 141T. Therefore, the angular velocity ω of the permanent magnet motor generator 14, based on the electrical angle of the starter-generator, is greater than, for example, a configuration having magnetic poles two-thirds or less of the number of teeth 141T. This results in a high field-weakening effect. Furthermore, because the number of magnetic poles 142a is more than two-thirds the number of teeth 141T, the size of the magnetic poles 142a themselves is small. Therefore, the magnetic flux resulting from the magnetic poles 142a is easily weakened by the magnetic field of the winding 141W through which the d-axis current flows. Therefore, at the maximum output rotation speed NmaxP, the output torque Ta of the permanent magnet motor generator 14 is greater than the output torque Tc of a configuration having magnetic poles two-thirds or less of the number of teeth 141T.

[0075] The output power Pma of the permanent magnet motor generator 14 depends on the product of the output torque and the rotational speed. Even at the maximum output rotational speed NmaxP, the output power Pma of the permanent magnet motor generator 14, which is field-weakening controlled, can be obtained. Therefore, the permanent magnet motor generator 14 receives power from the high-voltage power storage device 16 via the high-voltage power supply system 13, and can provide sufficient driving force to the crankshaft 11a over a wide rotational speed range of the engine 11, including the maximum output rotational speed NmaxP. Furthermore, the permanent magnet motor generator 14 can assist the engine 11 with the power of the high-voltage power storage device 16, which operates at high voltage, over a wide rotational speed range of the engine 11.

[0076] Next, an example of the characteristics of the permanent magnet motor generator 14 functioning as a generator during power generation will be described with reference to part (b) of Fig. 2. The solid line Pma in part (b) of Fig. 1 represents the output power. Power generation by the permanent magnet motor generator 14 is affected by the reluctance L·ω of the winding 141W.

[0077] The MG control device 15 causes the permanent magnet motor generator 14 to generate power while performing field-weakening control using high voltage as a power source. The graph of the output power Pga during power generation is approximately symmetrical to part (a) of FIG. 2 . In other words, at the maximum output rotation speed NmaxP, the output power Pga of the permanent magnet motor generator 14 under field-weakening control is greater than, for example, the output power without field-weakening control. Accordingly, the output power Pga of the permanent magnet motor generator 14 can charge the high-voltage power storage device 16 over a wide range of rotation speeds, including the maximum output rotation speed NmaxP. Therefore, the permanent magnet motor generator 14 can supply sufficient power to charge the high-voltage power storage device 16 via the high-voltage power supply system 13.

[0078] The d-axis current and q-axis current described above can be easily controlled explicitly and independently by adopting vector control as the control method for the MG control device 15. However, the control method for implementing field weakening in the MG control device 15 is not particularly limited. Field weakening control can be implemented by adjusting the timing at which current is received by the windings 141W of each phase.

[0079] According to this embodiment, the permanent magnet motor generator 14 can be operated over a wide rotational speed range from low to high rotational speeds. The permanent magnet motor generator 14 can operate over a wide rotational speed range including the maximum output rotational speed NmaxP. According to this embodiment, fluctuations in the generated voltage can be suppressed over a wide rotational speed range from low to high rotational speeds of the engine 11 of the saddle riding type vehicle 10. As a result, changes in the voltage supplied from the permanent magnet motor generator 14 to the high-voltage power supply system 13 via the MG control device 15 in response to changes in rotational speed are suppressed. Therefore, the high-voltage storage device 16 can be charged with a high voltage with suppressed fluctuations over a wide rotational speed range of the engine 11 of the saddle riding type vehicle 10 without providing the engine 11 with a speed reduction mechanism such as a belt or chain. Therefore, in the saddle-riding vehicle 10 of this embodiment, greater voltage suppression by field-weakening control is exerted in the higher rotational speed range, resulting in a synergistic effect, making it possible to charge the high-voltage electricity storage device 16 with voltage fluctuations suppressed over a wide rotational speed range including the high rotational speed range of the engine 11 of the saddle-riding vehicle 10, and also making it possible to perform engine assist control by the permanent magnet motor generator 14 over a wide rotational speed range of the engine 11 of the saddle-riding vehicle 10 using power from the high-voltage electricity storage device 16. Therefore, the high-voltage hybrid system HV is small and lightweight, and can be used over the rotational speed range of the engine 11 of the saddle-riding vehicle 10.

[0080] Fig. 3 is a block diagram showing the flow of current in the high-voltage hybrid system shown in Fig. 1. Part (a) of Fig. 3 shows the charged state of the high-voltage storage device, and part (b) of Fig. 3 shows the discharged state of the high-voltage storage device.

[0081] As shown in part (a) of FIG. 3 , when an acceleration request is input while the engine 11 is running, high-voltage power is supplied from the permanent magnet motor generator 14 to the high-voltage storage device 16 via the MG control device 15 and the high-voltage power supply system 13. This charges the high-voltage storage device. As shown in part (b) of FIG. 3 , when the high-voltage storage device 16 discharges, the permanent magnet motor generator 14 receives the power discharged from the high-voltage storage device 16 and applies torque to the crankshaft 11a through power running. In other words, the permanent magnet motor generator 14 can assist the engine 11 without a secondary battery that functions at high voltage. This also allows the engine 11 to be made smaller. This allows the high-voltage hybrid system HV included in the saddle-ride type vehicle 10 to be made smaller and lighter while suppressing a decrease in torque or power transmitted to the drive wheels 12a.

[0082] [Second embodiment] Fig. 4 is a block diagram showing a second embodiment, in which part (a) of Fig. 4 is a block diagram showing the current in the starting state, and part (b) of Fig. 4 is a block diagram showing the current in the charging state.

[0083] The saddle-type vehicle 10 shown in Figure 4 includes a starter motor 21 that starts the engine 11. The starter motor 21 drives, for example, the crankshaft 11a during starting. The starter motor 21 operates on the low voltage of the low-voltage power supply system 17 to start the engine 11 without powering the permanent magnet motor generator 14. The starter motor 21 operates on the low voltage discharged from a low-voltage battery 22 connected to the low-voltage power supply system 17.

[0084] The above points are the main differences from the first embodiment. Hereinafter, the differences from the first embodiment will be mainly described, and the same reference numerals will be used to denote elements common to the first embodiment, and description thereof will be omitted.

[0085] The saddle-type vehicle 10 of this embodiment includes a starter motor 21 that operates at a low voltage and starts the engine 11. Therefore, the engine 11 can be started even if the permanent magnet motor generator 14 does not have the function of starting the engine 11. For example, as shown in part (a) of FIG. 4 , when starting the engine 11, current flows from the low-voltage battery 22 to the starter motor 21 to supply power. The starter motor 21 starts the engine 11 using power from the low-voltage battery 22. After the engine 11 starts, the permanent magnet motor generator 14 is driven by the engine 11 to generate power. As shown in part (b) of FIG. 4 , the current generated by the permanent magnet motor generator 14 flows from the high-voltage power supply system 13 to the low-voltage power supply system 17 via the DC-DC converter 18. The DC-DC converter 18 converts the high voltage generated by the permanent magnet motor generator 14 to a low voltage. The current supplied via the DC-DC converter 18 is stored in the low-voltage battery 22.

[0086] Generally, a motor that starts the engine 11 outputs a torque large enough to start the engine 11, and therefore, for example, it is often necessary to strengthen the magnetic flux of the magnet. However, in this embodiment, the starting function is omitted from the permanent magnet motor generator 14, which increases the structural freedom, for example, by allowing magnets with weak magnetic flux to be used as the magnets that make up the magnetic poles 142a. Therefore, the permanent magnet motor generator 14 can be configured to output power corresponding to the high-voltage power supply system 13 over a range that is closer to the dynamic range of the rotational speed of the engine 11. As a result, the high-voltage hybrid system HV included in the saddle-ride type vehicle 10 can be made smaller and lighter.

[0087] REFERENCE SIGNS LIST 10 saddle-ride type vehicle 11 engine 11a crankshaft 12a drive wheel 13 high-voltage power supply system 14 permanent magnet motor generator 15 MG control device 16 high-voltage storage device 17 low-voltage power supply system 21 starter motor 141 stator 141T teeth 141W winding 142 rotor 142a magnetic pole

Claims

1. A saddle-ride type vehicle comprising: an engine having a crankshaft and outputting torque via the crankshaft; drive wheels to which at least a portion of the torque output from the engine is mechanically transmitted and which drive a saddle-ride type vehicle; a high-voltage power supply system which operates at a high voltage higher than the low voltage of a low-voltage power supply system to which a low-voltage battery is connected; a permanent magnet motor generator which includes a stator having a plurality of teeth arranged in the circumferential direction and windings wound around each of the plurality of teeth, and a rotor having magnetic poles provided on a rotating shaft which is coaxial with and rotates at the same speed as the crankshaft, and which applies torque to the drive wheels by powering while receiving and transmitting power from the high-voltage power supply system, and which generates electricity by receiving torque from the engine or the drive wheels; an MG control device which is electrically connected to the high-voltage power supply system and is electrically connected to the permanent magnet motor generator and controls the powering and power generation of the permanent magnet motor generator; and a high-voltage electricity storage device which is electrically connected to the high-voltage power supply system and which charges and discharges at the high voltage which is higher than the low voltage, wherein the MG control device The field weakening control is performed on the permanent magnet motor generator, which rotates at the same speed as the engine of the saddle-ride type vehicle and has a rotor with magnetic poles that are more than 2 / 3 of the number of teeth, using the high voltage, which is higher than the low voltage of the low-voltage battery, as a power source, so that the amount of voltage suppression by the field weakening control is increased due to the increase in reluctance caused by the increase in magnetic poles of the permanent magnet motor generator, and the field weakening control using the high voltage as a power source overcomes the reluctance that increases at high rotation speeds of the engine of the saddle-ride type vehicle and supplies a current component of the field weakening control to the windings.

2. A saddle-ride type vehicle as described in claim 1, further comprising a starter motor that operates at the low voltage of the low-voltage power supply system to start the engine without powering the permanent magnet motor generator, and the MG control device performs the field-weakening control on the permanent magnet motor generator that rotates at the same speed as the engine of the saddle-ride type vehicle and has a rotor with magnetic poles that number more than two-thirds of the number of teeth, using as a power source the high voltage that is higher than the low voltage of the low-voltage battery that operates the starter motor.

3. A saddle-ride type vehicle as claimed in claim 1 or 2, wherein the high-voltage storage device is a capacitor or a secondary battery, the permanent magnet motor generator receives power from the capacitor to power it and apply torque to the crankshaft, and the MG control device performs the field-weakening control on the permanent magnet motor generator, which rotates at the same speed as the engine of the saddle-ride type vehicle and has a rotor with magnetic poles that have more than 2 / 3 the number of teeth, using the high voltage, which is higher than the low voltage of the low-voltage battery and to which the capacitor or the secondary battery is connected, as a power source.

4. A saddle-ride type vehicle as claimed in claim 3, wherein the secondary battery is a high-current rechargeable lithium-ion battery that satisfies high-current discharge specifications and high-current charging specifications, the permanent magnet motor generator receives power from the high-current rechargeable lithium-ion battery and powers it to apply torque to the crankshaft, the high-current discharge specifications meaning a battery specification that allows for discharging at a maximum current during use corresponding to a rate of 10C or more for a charge capacity of 2.5 Ah, and the high-current charging specifications meaning a battery specification that allows for charging at a maximum current during use corresponding to a rate of 10C or more for a charge capacity of 2.5 Ah, and the MG control device performs the field-weakening control on the permanent magnet motor generator, which rotates at the same speed as the engine of the saddle-ride type vehicle and has a rotor with magnetic poles that are more than 2 / 3 the number of the teeth, using the high voltage, which is higher than the low voltage of the low-voltage battery and to which the high-current rechargeable lithium-ion battery is connected, as a power source.

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