straddle vehicle

Abstract

The object of this invention is to provide a motorcycle including a small and lightweight high-voltage hybrid power system, capable of adapting to the engine speed range of the motorcycle. The motorcycle includes an engine, drive wheels, a high-voltage power supply system, a permanent magnet electric generator, and a high-voltage energy storage device. The MG control unit uses a high voltage (higher than the low voltage of a low-voltage battery) as a power source to perform field weakening control on the permanent magnet electric generator. The engine includes a rotor that rotates at the same speed as the motorcycle's engine. The permanent magnet electric generator has a number of magnetic poles greater than 2 / 3 of the number of teeth, such that the voltage suppression achieved by field weakening control increases due to the increased reactance caused by the increased number of magnetic poles in the permanent magnet electric generator. Furthermore, by using high voltage as a power source for field weakening control, the increased reactance in the high-speed range of the motorcycle's engine is overcome, and the current component of the field weakening control is supplied to the windings.

Description

Technical Field

[0001] This instruction pertains to a straddle-mounted vehicle. Background Technology

[0002] For example, Patent Document (PTL) 1 discloses a vehicle including an electric generator connected to an engine. The vehicle disclosed in Patent Document 1 is an automobile (Patent Document 1's...). Figure 2 The electric generator is connected to the high-voltage battery via an inverter.

[0003] Patent Document 2 also discloses a car including an electric generator. The electric generator disclosed in Patent Document 2 is connected to the engine via a reduction gear (such as a belt or chain). The electric generator is supplied with high-voltage power by an energy storage device. The power generated by the electric generator is supplied to the energy storage device at high voltage.

[0004] For example, Patent Document 3 discloses a straddle-type vehicle. The straddle-type vehicle disclosed in Patent Document 3 includes an engine, a starter generator, a battery, and a control unit. The battery is a low-voltage battery that drives the starter generator. The control unit in PTL 3 performs field weakening control on the starter generator to prevent a voltage higher than the battery voltage from being applied to the low-voltage battery.

[0005] Citation List Patent documents Patent Document 1: Japanese Patent Application Publication No. H9-084210 Patent Document 2: Japanese Patent Application Publication No. 2005-180254 Patent Document 3: Japanese Patent Application Publication No. 2017-129065 Summary of the Invention

[0006] Technical issues It is generally desirable for motorcycles to include a compact and lightweight high-voltage hybrid system that can adapt to the engine speed range of the motorcycle.

[0007] The purpose of this instruction is to provide a motorcycle that includes a compact and lightweight high-voltage hybrid system and is adaptable to the engine speed range of the motorcycle.

[0008] Motorcycles are designed to be controlled by shifting the rider's center of gravity during riding. Therefore, from a maneuverability and riding performance perspective, a compact and lightweight design is desirable. Consequently, a compact and lightweight hybrid system and its components installed on a motorcycle are also desirable.

[0009] High-voltage compatible electric generators have a structure that can generate the required electricity even at low engine speeds, including, for example, idling speeds. For example, to generate a higher induced electromotive force, high-voltage compatible electric generators include stronger magnets compared to high-voltage incompatible electric generators.

[0010] For example, the high-voltage compatible electric generator for automobiles disclosed in Patent Document 1 or Patent Document 2 can be applied to motorcycle-type vehicles.

[0011] However, motorcycle engines tend to operate over a wider RPM range than automobile engines, including high RPMs. This is because automobile engines are configured to deliver high torque at low RPMs to start and accelerate heavy vehicles, while motorcycle engines are configured to start and accelerate the relatively light motorcycle, and it is desirable for motorcycle engines to be compact and lightweight so that they can be fitted into compact and lightweight motorcycles.

[0012] In cases where an electric generator with a high-voltage compatible configuration is driven by the engine of a motorcycle operating over a wide speed range, the induced electromotive force (EMF) of the electric generator may become excessively high at the high engine speeds, and the generator's terminal voltage may exceed the controllable range of the control unit. For example, if the generator's terminal voltage exceeds the controllable range, power generation control needs to be stopped. Furthermore, when power is supplied from a battery to the electric generator to assist engine rotation, the induced EMF, which counteracts the battery voltage, may become excessively high, potentially interfering with the control of the electric generator's electric operation.

[0013] One possible method to reduce the voltage of the electric generator is, as disclosed in Patent Document 2, to connect the motor of the motorcycle to the electric generator and use a reduction mechanism, such as a belt or chain, in between. However, providing a reduction mechanism for the electric generator would increase the size and weight of the hybrid system of the motorcycle.

[0014] The inventors of this teaching conducted a detailed study of a compact and lightweight configuration suitable for the engine speed range of a motorcycle. As a result, the inventors discovered a configuration in which a high voltage is used as a power source to perform field weakening control on a permanent magnet electric generator that rotates at the same speed as the motorcycle's engine, and wherein the number of magnetic poles is greater than 2 / 3 of the number of teeth. High voltage refers to a voltage higher than the low voltage of a low-voltage battery.

[0015] In permanent magnet electric generators with more poles, the angular velocity, expressed in electrical angles, is high. This configuration increases winding reactance, improving the voltage suppression level achieved through field weakening control. On the other hand, permanent magnet electric generators with more poles result in even higher angular velocities, which increase further when the motor of a motorcycle is running at high speeds. The increased winding reactance with increasing angular velocity is a component of impedance, and the further increase in impedance at high speeds hinders the current component for field weakening control. However, this problem is solved by using high voltage as the power source. Although the impedance increases due to more poles and high speeds, high voltage can drive the field weakening current to its target value. In other words, by using high voltage as the power source for field weakening control, the increased impedance at high speeds is overcome, and the current component used for field weakening control is supplied to the windings.

[0016] A more detailed description is given below.

[0017] The induced electromotive force E in the winding of a permanent magnet electric generator mainly depends on the product φ·ω of the magnetic flux φ linked with the winding and the electrical angle angular velocity ω.

[0018] In contrast, the main effective component of the terminal voltage generated by suppressing induced electromotive force (also known as "suppressed induced electromotive force") through field weakening control is represented by L·ω·Id. L·ω represents the reactance of the winding. L represents the inductance, which is typically a fixed value depending on the winding structure, etc. Id represents the field weakening current used in the field weakening control, the magnitude of which is controlled by the control unit. The angular velocity ω is based on the frequency of the periodic repetition of a pair of magnetic poles passing near the tooth. For example, the angular velocity ω is represented by the following equation: ω=(P / 2)×(N rpm / 60)×2π (P: number of magnetic poles, N: crankshaft speed) At high engine speeds in a motorcycle, a high induced electromotive force (EMF) E is generated in the windings due to the increase in φ·ω. In a configuration where the number of magnetic poles is greater than 2 / 3 of the number of teeth, the induced EMF E appears to increase with increasing angular velocity ω. However, allowing the number of magnetic poles to be greater than 2 / 3 of the number of teeth while keeping the size and weight of the permanent magnet generator the same results in a reduction in the physical size of each magnetic pole and a decrease in the magnetic flux φ linked to the windings. In other words, the reduction in magnetic flux φ offsets the increase in angular velocity ω. Therefore, the change in induced EMF E caused by more magnetic poles is minimized.

[0019] The field weakening control performed by the control unit can suppress the induced electromotive force that increases at high speeds. In a configuration where the number of magnetic poles is greater than 2 / 3 of the number of teeth, the angular velocity ω in the component L·ω·Id suppressed by field weakening control is higher than in a configuration where the number of magnetic poles is less than or equal to 2 / 3 of the number of teeth. Therefore, in a permanent magnet electric generator with a number of magnetic poles greater than 2 / 3 of the number of teeth, the level of suppression of induced electromotive force achieved by field weakening control is higher than in a configuration where the number of magnetic poles is less than or equal to 2 / 3 of the number of teeth.

[0020] The reactance L·ω of the winding, together with the pure resistance, constitutes the internal impedance Z of the winding. Impedance Z is the factor that impedes the current in the winding.

[0021] The field-weakening current Id is a current component controlled by the control unit. The field-weakening current Id also flows in a manner that impedes the winding impedance Z. As mentioned above, the reactance, which constitutes part of the winding impedance, is L·ω. An increase in angular velocity ω increases the reactance component, which manifests as an increase in impedance. For example, the control unit performs control through the duty cycle of the conduction time, ensuring that the field-weakening current Id remains at the target value regardless of changes in impedance Z. However, once the impedance Z increases beyond the controllable range, for example when the duty cycle reaches its upper limit, the control unit can no longer maintain the field-weakening current Id at the desired target value.

[0022] By using a high voltage as a power source to perform field weakening control, the control unit according to this disclosure can control the field weakening current Id, thereby maintaining the field weakening current Id at a target value by overcoming the increase in impedance Z caused by the increased reactance L·ω. That is, although the reactance L·ω increases due to the configuration where the number of magnetic poles is greater than 2 / 3 of the number of teeth, the control unit can maintain the field weakening current Id at the target value even at high engine speeds in a straddle-type vehicle.

[0023] As described above, in permanent magnet electric generators with a number of poles greater than two-thirds the number of teeth, high voltage is used as the power source to perform field weakening control. This configuration produces a synergistic effect, namely, that a higher level of voltage suppression can be achieved at higher engine speeds through field weakening control.

[0024] The synergistic effect of field weakening control, which enables higher levels of voltage suppression to take effect at higher speeds, allows high-voltage compatible permanent magnet electric generators to reduce output voltage fluctuations across a wide speed range of the motorcycle engine, from low to high speeds. This reduces the variation in voltage supplied by the permanent magnet electric generator to the high-voltage power supply system via the control unit as speed changes. Furthermore, by overcoming the induced electromotive force, power can be supplied to the electric generator from the battery, allowing for control of the electric generator's operation across a wide speed range of the motorcycle engine (from low to high speeds). Therefore, a high voltage with minimal fluctuations can be provided across a wide speed range of the motorcycle engine without requiring a reduction gear such as a belt or chain to the engine. Additionally, power from a high-voltage energy storage device can be used to control engine assistance via the electric generator across a wide speed range of the motorcycle engine.

[0025] Patent document 3 discloses an example in which field weakening control is performed on an electric generator including a rotor fixed to a crankshaft, and wherein the number of magnetic pole portions is 4 / 3 of the number of slots. However, the control unit in PTL 3 controls the starter generator while avoiding applying a voltage higher than the battery voltage of the low-voltage battery.

[0026] In contrast, the technology disclosed herein employs a method opposite to that of PTL 3, wherein the control unit avoids applying a voltage higher than the low-voltage battery voltage while performing control. That is, the technology disclosed herein intentionally uses a high voltage higher than the low-voltage battery voltage as a power source to perform field weakening control on a permanent magnet electric generator with a number of poles greater than 2 / 3 the number of teeth. Therefore, even at high speeds, the control unit can maintain the field weakening current Id, although the reactance L·ω increases due to the configuration of the increased reactance component, where the number of poles is greater than 2 / 3 the number of teeth. In other words, despite the increase in angular velocity ω, a field weakening control effect enhanced by the increased angular velocity ω can be produced over a wide speed range of the motor in the straddle-type vehicle.

[0027] According to the technology disclosed herein, voltage fluctuations can be reduced over a wide speed range (including high speeds) of the motorcycle engine due to the synergistic effect of enabling higher levels of voltage suppression to take effect at higher speeds via field weakening control. Furthermore, engine assistance can be controlled via an electric generator. Therefore, according to the technology disclosed herein, a compact and lightweight high-voltage hybrid power system can be realized, adaptable to the speed range of a motorcycle engine.

[0028] Solutions to technical problems To achieve the above objectives, a vehicle according to one aspect of this teaching has the following configuration.

[0029] (1) A straddle-type vehicle, comprising: An engine having a crankshaft and configured to output torque via said crankshaft; A drive wheel configured to receive at least a portion of the torque output from the engine and mechanically transmitted to the drive wheel to drive the straddle vehicle; A high-voltage power supply system configured to operate at a high voltage higher than the low voltage of a low-voltage power supply system, the low-voltage power supply system having a low-voltage battery connected to the low-voltage power supply system. A permanent magnet electric generator configured to transmit power to and from the high-voltage power supply system, apply torque to a drive wheel by electric operation, and generate power by receiving torque from the engine or the drive wheel, the permanent magnet electric generator comprising a stator and a rotor, the stator having a plurality of teeth arranged in a circumferential direction and a winding wound on each of the plurality of teeth, the rotor having magnetic poles and being disposed on a rotating shaft coaxial with the crankshaft and rotating at the same speed as the crankshaft; An MG control unit, electrically connected to the high-voltage power supply system and also electrically connected to the permanent magnet electric generator, is configured to control the electric operation and power generation of the permanent magnet electric generator; and A high-voltage energy storage device, electrically connected to the high-voltage power supply system, and configured to charge and discharge at a high voltage higher than the low voltage, wherein... The MG control unit uses a high voltage, higher than the low voltage of the low-voltage battery, as a power source to perform field weakening control on the permanent magnet electric generator, which includes a rotor that rotates at the same speed as the motor of the motorcycle, and wherein the number of magnetic poles is greater than 2 / 3 of the number of teeth, such that the voltage suppression level achieved by the field weakening control increases due to the increased reactance caused by the greater number of magnetic poles of the permanent magnet electric generator, and such that by using the field weakening control powered by a high voltage, the increased reactance at high speeds of the motor of the motorcycle is overcome, and the current component for the field weakening control is supplied to the winding.

[0030] The straddle-type vehicle described in (1) includes an engine, drive wheels, a high-voltage power supply system, a permanent magnet electric generator, a high-voltage energy storage device, and an MG (electric generator) control unit.

[0031] The engine has a crankshaft. The engine outputs torque through the crankshaft. The drive wheels drive the motorcycle. At least a portion of the torque output from the engine is mechanically transmitted to the drive wheels.

[0032] The high-voltage power supply system operates at a high voltage. High voltage refers to a voltage higher than the low voltage of the low-voltage power supply system connected to a low-voltage battery. The battery is a secondary battery. The permanent magnet electric generator (PMG) consists of a stator and a rotor. The stator has multiple teeth and windings. The multiple teeth are arranged circumferentially. The windings are wound on each of the multiple teeth. The rotor is mounted on a rotating shaft coaxial with the crankshaft and rotating at the same speed. The rotor has magnetic poles. The PMG transmits electricity to and from the high-voltage power supply system. The PMG applies torque to the drive wheels through electric operation. The PMG generates electricity by receiving torque from the engine or drive wheels. The MG control unit is electrically connected to the high-voltage power supply system. The MG control unit is also electrically connected to the PMG. The MG control unit controls the electric operation and power generation of the PMG.

[0033] A motorcycle-type vehicle is a hybrid vehicle. The engine, drive wheels, high-voltage power supply system, permanent magnet electric generator, and MG control unit are included in the high-voltage hybrid system of the motorcycle-type vehicle.

[0034] The motorcycle also includes a high-voltage energy storage device. This high-voltage energy storage device is electrically connected to a high-voltage power supply system. The high-voltage energy storage device charges and discharges at a high voltage, higher than the low voltage.

[0035] The design of a motorcycle is intended to allow the vehicle's posture to be controlled as the rider's center of gravity shifts during riding. Therefore, from a maneuverability and riding performance perspective, a compact and lightweight motorcycle is desirable. Consequently, a compact and lightweight hybrid system and its components mounted on a motorcycle are also desirable. In cases where an electric generator with a high-voltage compatible configuration is driven by the motorcycle's engine operating over a wide speed range, the induced electromotive force of the electric generator may become excessively high at the high engine speeds, and the generator's terminal voltage may exceed the controllable range of the control unit.

[0036] In the straddle-type vehicle described in (1), the MG control unit uses a high voltage (higher than the low voltage of the low-voltage battery) as a power source to perform field weakening control on a permanent magnet electric generator including a rotor that rotates at the same speed as the straddle-type vehicle's engine, and the number of magnetic poles is greater than 2 / 3 of the number of teeth. Therefore, by using a high voltage as a power source to perform field weakening control, the voltage suppression level achieved through field weakening control increases due to the increased reactance caused by the increased number of magnetic poles in the permanent magnet electric generator, and the increased reactance at high engine speeds of the straddle-type vehicle is overcome by using field weakening control powered by a high voltage, allowing the current component used for field weakening control to be supplied to the windings. It should be noted that the increase in reactance due to the increased number of magnetic poles means that the number of magnetic poles is greater than 2 / 3 of the number of teeth.

[0037] The field weakening control performed by the control unit can suppress the induced electromotive force that increases at high speeds. In a configuration where the number of magnetic poles is greater than 2 / 3 of the number of teeth, the angular velocity ω in the component L·ω·Id suppressed by field weakening control is higher than in a configuration where the number of magnetic poles is less than or equal to 2 / 3 of the number of teeth. Therefore, in a permanent magnet electric generator with a number of magnetic poles greater than 2 / 3 of the number of teeth, the level of suppression of induced electromotive force achieved by field weakening control is higher than in a configuration where the number of magnetic poles is less than or equal to 2 / 3 of the number of teeth. L represents inductance. Id represents the field weakening current used in field weakening control. ω represents the angular velocity expressed in electrical angles. L·ω represents the reactance of the winding.

[0038] The reactance L·ω of the winding, together with the pure resistance, constitutes the internal impedance Z of the winding. Impedance Z is the factor that impedes the current in the winding.

[0039] The field-weakening current Id is a current component controlled by the control unit. The field-weakening current Id also flows in a manner that impedes the winding impedance Z. As mentioned above, the reactance that constitutes part of the winding impedance is L·ω, and it increases with increasing angular velocity ω. For example, the control unit controls the conduction time duty cycle so that the field-weakening current Id remains at a target value regardless of changes in impedance Z. However, once the impedance Z increases beyond a controllable range, for example when the duty cycle reaches its upper limit, the control unit can no longer maintain the field-weakening current Id at the desired target value.

[0040] By using a high voltage as a power source to perform field weakening control, the control unit according to this disclosure can control the field weakening current Id, thereby maintaining the field weakening current Id at a target value by overcoming the increase in impedance Z caused by the increased reactance L·ω. That is, although the reactance L·ω increases due to the configuration where the number of magnetic poles is greater than 2 / 3 of the number of teeth, the control unit can maintain the field weakening current Id at the target value even at high engine speeds in a straddle-type vehicle.

[0041] As described above, in permanent magnet electric generators with more than two-thirds the number of magnetic poles, high voltage is used as the power source to perform field weakening control. This configuration produces a synergistic effect, namely, through field weakening control, a higher level of voltage suppression can be achieved at higher engine speeds.

[0042] The synergistic effect of higher-level voltage suppression through field weakening control at higher speeds enables high-voltage compatible permanent magnet electric generators to reduce output voltage fluctuations across a wide speed range (from low to high) of the motorcycle engine. This reduces the variation in voltage supplied by the permanent magnet electric generator to the high-voltage power supply system via the control unit as speed changes. Furthermore, power from the high-voltage energy storage device can be used to control engine assistance via the permanent magnet electric generator across a wide speed range of the motorcycle engine. Therefore, the high-voltage energy storage device can be charged with a less volatile high voltage across a wide speed range of the motorcycle engine without requiring a reduction gear such as a belt or chain to the engine, and engine assistance can be controlled via the permanent magnet electric generator across a wide speed range of the motorcycle engine using power from the high-voltage energy storage device.

[0043] In the straddle-type vehicle described in (1), the synergistic effect of enabling higher levels of voltage suppression to take effect at higher speeds through field weakening control allows for reduced voltage fluctuations across a wide speed range (including high speeds) of the straddle-type vehicle's engine. Furthermore, power from a high-voltage energy storage device can be used to control engine assistance via a permanent magnet electric generator across the wide speed range of the straddle-type vehicle's engine. Therefore, a compact and lightweight high-voltage hybrid power system can be realized, adaptable to the speed range of the straddle-type vehicle's engine.

[0044] According to one aspect of this teaching, the vehicle may be configured as follows.

[0045] (2) The straddle-type vehicle described in (1) also includes A starter motor, configured to operate at a low voltage in the low-voltage power supply system, is provided to start the engine without requiring the permanent magnet electric generator to operate electrically. The MG control unit uses a high voltage higher than the low voltage of the low-voltage battery as a power source to perform the field weakening control on the permanent magnet electric generator including the rotor. The low voltage is used for the operation of the starter motor. The rotor rotates at the same speed as the engine of the straddle vehicle, and the number of magnetic poles is greater than 2 / 3 of the number of teeth.

[0046] The straddle-type vehicle described in (2) includes a starter motor that operates at low voltage to start the engine. Therefore, the engine can be started even if the permanent magnet electric generator does not have an engine-starting function. Generally, motors used for starting engines often need to output sufficiently high torque to start the engine. Therefore, for example, it is usually necessary to increase the magnetic flux of the magnet. However, the permanent magnet electric generator omits the starting function, increasing configuration freedom, for example, allowing the use of a weaker magnet than that of a permanent magnet electric generator with a starting function. The MG control unit uses a high voltage, higher than the low voltage of the low-voltage battery used for starting motor operation, as a power source to perform field weakening control on a permanent magnet electric generator that includes a rotor with more than 2 / 3 the number of magnetic poles. Because field weakening control is implemented using high voltage as a power source to suppress induced electromotive force at high speeds, the design freedom is high, allowing for a wider speed range of the straddle-type vehicle's engine. As a result, a compact, lightweight, and high-voltage hybrid system capable of adapting to a wider speed range can be realized.

[0047] According to one aspect of this teaching, the vehicle may be configured as follows.

[0048] (3) The straddle-type vehicle according to (1) or (2), wherein The high-voltage energy storage device is a capacitor or a secondary battery. The permanent magnet electric generator receives power from the capacitor to apply torque to the crankshaft via electric operation, and The MG control unit uses the high voltage of the high-voltage power system connected to the capacitor or secondary battery as a power source, the high voltage being higher than the low voltage of the low-voltage battery, to perform the field weakening control on the permanent magnet electric generator including the rotor, the rotor rotating at the same speed as the engine of the straddle vehicle, and wherein the number of magnetic poles is greater than 2 / 3 of the number of teeth.

[0049] The capacitor or secondary battery can be charged and discharged. The MG control unit uses a high voltage (higher than the low voltage of the low-voltage battery) from the capacitor or secondary battery as power to perform field weakening control on a permanent magnet electric generator, which includes a rotor with more than two-thirds the number of magnetic poles. The permanent magnet electric generator supplies power to the capacitor or secondary battery, thereby charging the capacitor. Furthermore, power from the capacitor or secondary battery can be used to control engine assistance via the permanent magnet electric generator. Therefore, a compact, lightweight, and adaptable high-voltage hybrid power system with a wider speed range can be realized.

[0050] According to one aspect of this teaching, the vehicle may be configured as follows.

[0051] (4) The straddle-type vehicle according to (3), wherein The secondary battery is a high-current charging drive lithium-ion battery that meets the specifications for both high-current charging and high-current discharging. The permanent magnet electric generator receives power from the high-current-chargeable drive lithium-ion battery to apply torque to the crankshaft via electric operation. The high-current discharge specification is that, for a charging capacity of 2.5Ah, the battery can discharge at a maximum operating current corresponding to 10C or higher. The high-current charging specification is that, for a charging capacity of 2.5Ah, the battery can be charged at a maximum operating current corresponding to a rate of 10C or higher; and The MG control unit uses the high voltage of the high-voltage power system connected to the high-current rechargeable drive lithium-ion battery as a power source, the high voltage being higher than the low voltage of the low-voltage battery, to perform field weakening control on the permanent magnet electric generator including the rotor, the rotor rotating at the same speed as the motor of the motorcycle, and wherein the number of magnetic poles is greater than 2 / 3 of the number of teeth.

[0052] According to (4), the secondary battery is a high-current rechargeable drive lithium-ion battery that meets both high-current charging and high-current discharging specifications. High-current discharging specifications mean that for a charging capacity of 2.5Ah, the battery can discharge at a maximum operating current corresponding to a rate of 10C or higher. High-current charging specifications mean that for a charging capacity of 2.5Ah, the battery can be charged at a maximum operating current corresponding to a rate of 10C or higher. The high-current rechargeable drive lithium-ion battery can be charged and discharged at high currents like a capacitor. Therefore, during the power generation process of a permanent magnet electric generator with more than 2 / 3 the number of poles, the high-current rechargeable drive lithium-ion battery can be quickly charged. Furthermore, during engine assistance via the permanent magnet electric generator, the high-current rechargeable drive lithium-ion battery can provide a large current to the permanent magnet electric generator.

[0053] The MG control unit uses a high-voltage power supply system connected to a capacitor or a high-current rechargeable drive lithium-ion battery as its power source. This high voltage is higher than the low voltage of a low-voltage battery. It performs field weakening control on a permanent magnet electric generator (PMG) with a rotor whose number of magnetic poles is greater than two-thirds the number of teeth. The PMG supplies power to the capacitor or the high-current rechargeable drive lithium-ion battery, thereby rapidly charging the high-current rechargeable drive lithium-ion battery. Furthermore, a large current from the high-current rechargeable drive lithium-ion battery can be used to control engine assistance via the PMG. Therefore, a compact, lightweight, and powerfully auxiliary high-voltage hybrid system capable of providing assistance over a wider speed range can be obtained.

[0054] The terminology used herein is for defining specific embodiments only and is not intended to limit the teachings. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. The terms “comprising,” “including,” or “having,” and variations thereof as used herein specify the presence of the stated features, steps, operations, elements, components, and / or their equivalents, and may include one or more steps, operations, and / or groups thereof. As used herein, the terms “attach,” “connect,” “couple,” and / or their equivalents are used broadly to include direct and indirect attachment, connection, and coupling. Furthermore, the terms “connect” and “couple” are not limited to physical or mechanical connections or couplings and may include direct or indirect electrical connections or couplings. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this teachings pertain. Terms, as defined in common dictionaries, should be interpreted as having meanings consistent with their meanings in the context of this disclosure and related technologies, and should not be interpreted in an idealized or overly formal sense unless expressly defined herein. It should be understood that the description of this teaching discloses numerous techniques and steps. Each of these techniques has its own advantages, and each can be used in conjunction with one or more, or in some cases with all other disclosed techniques. Therefore, for clarity, this description will avoid unnecessarily repeating every possible combination of the individual steps. However, upon reading the specification and claims, it should be understood that such combinations are entirely within the scope of these teachings and claims.

[0055] This specification describes a novel straddle-type vehicle. In the description given below, specific details are set forth for purposes of explanation in order to provide a thorough understanding of the teachings. However, it will be apparent to those skilled in the art that the teachings can be practiced without these specific details. This disclosure is to be regarded as illustrative of the teachings and is not intended to limit the teachings to the specific embodiments shown in the following figures or description.

[0056] A straddle-mounted vehicle is a vehicle that includes a saddle for the rider to straddle. A straddle-mounted vehicle is configured to control its attitude during riding by shifting the rider's center of gravity. Examples of straddle-mounted vehicles include scooters, mopeds, off-road motorcycles, and road motorcycles. A straddle-mounted vehicle is not limited to motorcycles; for example, it can be a three-wheeled or four-wheeled off-road vehicle called an ATV (All-Terrain Vehicle), and a snowmobile. For example, a straddle-mounted vehicle is a leaning vehicle that turns in a leaning posture. When turning, the leaning vehicle leans towards the center of the turn. For example, a leaning vehicle is a motorcycle or a motorized tricycle. The straddle-mounted vehicle according to this disclosure is a vehicle driven by the output of an engine. For example, a straddle-mounted vehicle does not include a bicycle. The leaning vehicle leans towards the center of the turn through operations including shifting the rider's center of gravity. The attitude of the straddle-mounted vehicle is controlled by the rider. Due to this characteristic, it is preferable that straddle-mounted vehicles achieve further reductions in size and weight.

[0057] An engine is an internal combustion engine. For example, an engine can be a single-cylinder engine or an engine with multiple cylinders. For example, an engine can be a four-stroke engine or a two-stroke engine. The engine of a motorcycle refers to the engine mounted on a motorcycle.

[0058] A drive wheel is a wheel that propels a motorcycle. A motorcycle can include wheels other than drive wheels. For example, a motorcycle includes a front wheel and a rear wheel. In this case, the drive wheel can be the rear wheel, the front wheel, or both the front and rear wheels.

[0059] A high-voltage power supply system refers to a system used to transmit high voltage. High voltage means a voltage higher than the low voltage of a low-voltage power supply system. In a straddle-type vehicle configuration that includes systems for transmitting high voltage and systems for transmitting low voltage, which are different from each other, the system used to transmit high voltage is the high-voltage power supply system. High voltage in a high-voltage power supply system at least means the voltage present when the engine is in combustion operation. When the engine is stopped, the voltage in the high-voltage power supply system can be a low voltage, including zero voltage.

[0060] For example, in a motorcycle, the high voltage is greater than 24V. In this case, the low voltage is less than or equal to 24V. Alternatively, the high voltage might be greater than 12V. In this case, the low voltage is less than or equal to 12V.

[0061] For example, in motorcycles where the high voltage does not exceed 60V, the motorcycle operates within the "extra-low voltage" (ELV or SELV) range defined by the International Electrotechnical Commission (IEC) standard IEC 60950. In this case, the insulation level of the power supply system is sufficient within the "operating insulation" range, allowing for a reduction in wiring area. However, there are no specific restrictions on the high voltage in motorcycles; for example, it can be greater than or equal to 60V.

[0062] Secondary batteries and capacitors are devices that can be charged and discharged.

[0063] A secondary battery is a rechargeable battery. It charges and discharges through chemical reactions at its electrodes. These reactions occur through oxidation and reduction at the electrodes. The secondary battery stores the electrical energy gained during charging as chemical energy. It then converts this stored chemical energy back into electrical energy.

[0064] The charging and discharging of a capacitor does not involve chemical reactions at its electrodes. A capacitor stores supplied electrical energy as charge.

[0065] For example, a high-current rechargeable lithium-ion battery is a secondary battery that includes a negative electrode comprising at least one selected from the group consisting of spinel-type lithium titanate, a composite oxide containing niobium and titanium, and graphite.

[0066] The charge rate in a battery indicates the rate at which charge is stored or released. The unit of charge rate is C. High-current charging specifications correspond to the maximum allowable charge rate during charging. High-current discharging specifications correspond to the maximum allowable discharge rate during discharging. The current corresponding to the maximum charge rate is the maximum operating current. The current required to fully charge a battery in one hour is defined as 1C. For example, in the case of a 2.5Ah battery, 1C corresponds to 2.5A.

[0067] Devices other than high-voltage energy storage devices can be electrically connected to a high-voltage power supply system. For example, a second electric generator, electric turbocharger, or electric supercharger positioned in the torque transmission path between the engine and drive wheels can be connected to a high-voltage power supply system. High-voltage loads operating at high voltage can also be connected to a high-voltage power supply system.

[0068] A permanent magnet electric generator is a rotating electrical machine that combines the functions of an electric motor and a generator. It uses permanent magnets to generate a magnetic field. Permanent magnet electric generators do not include induction motors or alternators that use electromagnets to generate a magnetic field.

[0069] For example, a permanent magnet electric generator is an external rotor type. However, there are no particular limitations on permanent magnet electric generators; for example, it can be an internal rotor type. A permanent magnet electric generator is, for example, a surface permanent magnet (SPM) motor. However, there are no particular limitations on permanent magnet electric generators; for example, it can be an internal permanent magnet (IPM) motor.

[0070] For example, a permanent magnet electric generator with more than 2 / 3 the number of magnetic poles is a permanent magnet electric generator with more than or equal to 4 / 3 the number of magnetic poles.

[0071] Examples of such permanent magnet electric generators include those where the number of magnetic poles is 4 / 3 of the number of teeth. However, there are no particular restrictions on the relationship between the number of magnetic poles and the number of teeth in a permanent magnet electric generator, as long as the number of magnetic poles is greater than 2 / 3 of the number of teeth. Examples of configurations that satisfy this relationship include configurations where the number of magnetic poles is 5 / 6, 8 / 9, 11 / 12, 13 / 12, or 14 / 12 of the number of teeth.

[0072] In configurations where the number of magnetic poles is greater than two-thirds the number of teeth, the angular velocity ω is larger, leading to increased reactance at high speeds. Therefore, the suppression of voltage fluctuations through field weakening control is highly effective. For example, in configurations where the number of magnetic poles is a multiple of two, such as a configuration where the number of magnetic poles is four-thirds the number of teeth, it is easy to form and set paired magnetic poles in the circumferential direction. In configurations where the number of teeth is a multiple of three, the permanent magnet generator can operate efficiently using three-phase drive current. In configurations where the number of magnetic poles is less than or equal to four-thirds the number of teeth, sufficient magnetic flux density can be maintained at each magnetic pole while keeping the size and weight of the permanent magnet generator constant.

[0073] For example, a rotating shaft equipped with a rotor, that is, a rotating shaft coaxial with the crankshaft and rotating at the same speed, is the crankshaft itself. In this case, the rotor is mounted on a portion of the crankshaft. However, there are no particular restrictions on the type of rotating shaft; it can be separate from the crankshaft, coaxial with the crankshaft, and connected to the crankshaft using a connecting member such as a connecting sleeve. However, for example, a shaft connected to the crankshaft via planetary gears does not fall under the definition of a rotating shaft coaxial with the crankshaft and rotating at the same speed, because such a shaft does not rotate at the same speed as the crankshaft.

[0074] The MG control unit includes, for example, a processor that executes programs and a memory that stores programs and data. The control unit is implemented, for example, by the processor executing programs stored in the memory. However, the structure of the control unit is not particularly limited and can be logic circuitry that processes data without relying on a processor or program.

[0075] The MG control unit may additionally include functions for controlling the engine, for example. However, there are no particular limitations on the MG control unit; for example, it can be separated from the control unit for controlling the engine.

[0076] Field weakening control refers to controlling the current in the windings so that the current component that weakens the magnetic field generated by the permanent magnets of the generator flows through the windings. This field-weakening current component corresponds to the d-axis component in the q-axis and d-axis components of a vector control scheme. However, there are no particular restrictions on the control method, as long as the field-weakening current component flows through the windings due to the control. For example, the control method could be phase control, which directly controls the phase of the current relative to the electrical angle phase, without explicitly handling the d-axis component.

[0077] Beneficial effects of the invention According to this teaching, a motorcycle can be provided that includes a high-voltage hybrid system, which is compact and lightweight and can adapt to the engine speed range of the motorcycle. Attached Figure Description

[0078] Figure 1 This is a schematic diagram illustrating a straddle-type vehicle according to a first embodiment.

[0079] Figure 2 It is shown schematically. Figure 1 The diagram illustrates the role of field weakening control in a permanent magnet electric generator.

[0080] Figure 3 It is shown Figure 1 The diagram shows the current flow in a high-voltage hybrid power system.

[0081] Figure 4 This is a block diagram illustrating the second embodiment. Detailed Implementation

[0082] The following description, with reference to the accompanying drawings, illustrates a straddle-type vehicle according to some embodiments. It should be noted that the embodiments described below are merely examples. This teaching should not be interpreted in a limiting manner based on the embodiments described below.

[0083] [First Embodiment] Figure 1 This is a schematic diagram illustrating a straddle-type vehicle according to a first embodiment. Figure 1 Part (a) is a schematic side view of a straddle-mounted vehicle. Figure 1 Part (b) is a block diagram showing a summary configuration of a high-voltage hybrid system for a motorcycle. Figure 1 (c) is Figure 1 (b) is a side view of an example of the detailed structure of a permanent magnet electric generator.

[0084] Figure 1 Part (d) is a block diagram showing the equivalent circuit of the windings in a permanent magnet electric generator. Figure 1 Part (e) is a vector diagram illustrating the effect of magnetic weakening control. Figure 1 Part (f) is a graph showing the characteristics of reactance versus rotational speed. Figure 1 Part (g) is a graph showing the characteristics of the weak magnetic current versus the rotational speed.

[0085] Figure 1 The straddle-type vehicle 10 shown includes an engine (EG) 11, drive wheels 12a, a high-voltage power supply system 13, a permanent magnet electric generator 14, and an MG control unit (MGCU) 15.

[0086] Engine 11 has a crankshaft 11a. Engine 11 generates power by burning a gas mixture containing air and fuel. Engine 11 outputs power in the form of rotational torque. Engine 11 outputs torque via crankshaft 11a.

[0087] Drive wheel 12a drives the motorcycle 10. The motorcycle 10 has multiple wheels 12a and 12b. Wheel 12a serves as drive wheel 12a. At least a portion of the torque output from engine 11 is mechanically transmitted to drive wheel 12a.

[0088] The high-voltage power system 13 delivers power at a higher voltage Vhigh than the low voltage Vlow of the low-voltage power system 17. No battery is connected to the high-voltage power system 13. The motorcycle 10 does not have a battery that operates at the high voltage Vhigh. Figure 1 In the example shown, low-voltage power supply system 17 is connected to high-voltage power supply system 13 via DC-DC converter 18. The high voltage Vhigh of high-voltage power supply system 13 is converted to a low voltage Vlow by DC-DC converter 18 and supplied to low-voltage power supply system 17. Low-voltage device 19, operating at low voltage Vlow, is connected to low-voltage power supply system 17. Low-voltage battery 22, operating at low voltage Vlow, is connected to low-voltage power supply system 17.

[0089] The permanent magnet electric generator 14 is electrically connected to the high-voltage power supply system 13. More specifically, the permanent magnet electric generator 14 is electrically connected to the high-voltage power supply system 13 via an MG control unit (MGCU) 15. The permanent magnet electric generator 14 applies torque to the drive wheel 12a via electric operation. More specifically, the permanent magnet electric generator 14 applies torque to the crankshaft 11a via electric operation. For example, the permanent magnet electric generator 14 assists the drive of the engine 11 via electric operation. The permanent magnet electric generator 14 receives torque from the engine 11 or the drive wheel 12a, thereby generating electricity. The MG control unit 15 controls the electric operation and power generation of the permanent magnet electric generator 14.

[0090] The motorcycle 10 is a hybrid vehicle. The motorcycle 10 includes a high-voltage hybrid system HV. The high-voltage hybrid system HV of the motorcycle 10 includes an engine 11, drive wheels 12a, a high-voltage power supply system 13, a permanent magnet electric generator 14, and an MG control unit 15.

[0091] The motorcycle 10 also includes a high-voltage energy storage device 16 electrically connected to a high-voltage power supply system 13. The high-voltage energy storage device 16 is charged and discharged at a high voltage higher than the low voltage.

[0092] For example, the high-voltage energy storage device 16 in this embodiment is a capacitor or a secondary battery.

[0093] Examples of suitable rechargeable batteries include high-current rechargeable drive lithium-ion batteries that meet both high-current charging and high-current discharging specifications. High-current discharging specifications mean that the battery can discharge at a maximum operating current corresponding to a rate of 10C or higher for a charging capacity of 2.5Ah. High-current charging specifications mean that the battery can be charged at a maximum operating current corresponding to a rate of 10C or higher for a charging capacity of 2.5Ah. High-current rechargeable drive lithium-ion batteries can be charged and discharged at high currents like capacitors. Therefore, high-current rechargeable drive lithium-ion batteries can charge quickly and output high currents. Examples of suitable high-current rechargeable drive lithium-ion batteries include those with a configuration including a negative electrode comprising one of spinel-type lithium titanate, a composite oxide containing niobium and titanium, and graphite.

[0094] like Figure 1 As shown in part (c), the permanent magnet electric generator 14 in the straddle vehicle 10 includes a stator 141 and a rotor 142.

[0095] The stator 141 has a plurality of teeth 141T arranged in a circumferential direction, i.e., in the direction of rotation of the rotor 142, and a winding 141W wound on each of the plurality of teeth 141T. More specifically, the plurality of teeth 141T are arranged to be spaced apart by slots 141S.

[0096] The rotor 142 is mounted on a rotating shaft that is coaxial with the crankshaft 11a and rotates at the same speed.

[0097] In this embodiment, the crankshaft 11a itself is the rotating shaft coaxial with and rotating at the same speed as the crankshaft 11a. The rotor 142 is mechanically connected to the end of the crankshaft 11a. In other words, the permanent magnet electric generator 14 is connected to the end of the crankshaft 11a. The rotor 142 has magnetic poles 142a, the number of which is greater than 2 / 3 of the number of teeth 141T. In the rotor 142 according to this embodiment, the number of magnetic poles 142a is 4 / 3 of the number of teeth 141T. The magnetic poles 142a are arranged along the direction of rotation. The magnetic poles 142a are composed of permanent magnets.

[0098] Figure 1 The example shown illustrates a structure in which the same number of permanent magnets as magnetic poles 142a are arranged along the circumferential direction. However, there are no particular limitations on the structure of magnetic poles 142a. For example, magnetic poles 142a can have a structure in which a single cylindrical permanent magnet is magnetized to generate multiple magnetic poles 142a, or a structure in which the cylindrical permanent magnet is divided into two or three blocks and magnetized to generate multiple magnetic poles 142a on each block.

[0099] The permanent magnet electric generator 14 is electrically connected to the permanent magnet turbine electric generator 161, which serves as a power transmission device, and the MG control unit 15 is located between the permanent magnet electric generator 14 and the permanent magnet turbine electric generator 161. The MG control unit 15 performs electric operation and power generation control, including field weakening control. The permanent magnet electric generator 14 transmits power to and from the permanent magnet turbine electric generator 161 via the MG control unit 15 without using a battery.

[0100] In a permanent magnet electric generator 14 configuration where the number of magnetic poles 142a is greater than 2 / 3 of the number of teeth 141T, the angular velocity ω, expressed in electrical angles, relative to the mechanical rotational speed of the rotor 142 is greater than, for example, in a configuration where the number of magnetic poles 142a is less than or equal to 2 / 3 of the number of teeth 141T. Mechanical rotational speed refers to the number of revolutions of the rotor 142 per unit time. Conversely, the angular velocity, expressed in electrical angles, is defined as the periodic repetition of the rotational angle based on a pair of magnetic poles 142a passing near a single tooth 141T.

[0101] The MG control unit 15 uses a high voltage Vhigh, which is higher than the low voltage of the low-voltage battery 22, as a power source to perform field weakening control on the permanent magnet electric generator 14, which includes a rotor 142 rotating at the same speed as the engine 11 of the motorcycle 10, and wherein the number of magnetic poles 142a is greater than 2 / 3 of the number of teeth 141T. Thus, by using the high voltage Vhigh as a power source to perform field weakening control, the voltage suppression level achieved by field weakening control increases due to the increase in reactance Lω caused by the increase in the number of magnetic poles 142a of the permanent magnet electric generator 14, and the increased reactance Lω at high speeds of the engine 11 of the motorcycle 10 is overcome by using field weakening control powered by the high voltage Vhigh, and the current component for field weakening control is supplied to the winding 141W.

[0102] like Figure 1 As shown in the equivalent circuit in part (d), the winding 141W electrically includes an AC voltage source 141A, an inductor 141B, and a resistor 141R.

[0103] The induced electromotive force E output by the AC voltage source 141A depends on the angular velocity ω. More specifically, the induced electromotive force E depends primarily on the product of the angular velocity ω and the magnetic flux φ linked with the winding 141W.

[0104] The inductance L of inductor 141B depends primarily on the magnetic flux linked to winding 141W. The product of angular velocity ω and inductance L is Lo. ω represents the reactance of the 141W winding. Reactance is expressed as L. ω or Lω.

[0105] The resistance R of resistor 141R represents the winding resistance. The impedance Z of winding 141W can be approximately expressed as follows.

[0106] ((Lω)^2+R^2)^1 / 2 exist Figure 1 In the vector diagram of part (e), 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 corresponding to the magnetic weakening current. Iq represents the q-axis current component.

[0107] Since the induced electromotive force E mainly depends on the product of the angular velocity ω and the magnetic flux φ linked with the winding 141W, the induced electromotive force E increases with the increase of the mechanical speed of the permanent magnet electric generator 14.

[0108] The voltage output from the permanent magnet electric generator 14 (in other words, the terminal voltage) is the result of the induced electromotive force E being affected by the current flowing through the winding 141W (in other words, the current flowing through the inductor 141B and the resistor 141R).

[0109] The current flowing through winding 141W includes a magnetic weakening current Id as a component. This magnetic weakening current Id generates magnetic flux along the direction of the magnetic flux produced by magnetic pole 142a, and is also referred to as the d-axis current Id. In contrast, the q-axis current Iq generates magnetic flux perpendicular to the direction of the magnetic weakening current Id in the vector diagram. This q-axis current generates magnetic flux perpendicular to the magnetic flux produced by magnetic pole 142a and is used to directly control the torque of the permanent magnet electric generator 14.

[0110] 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 weak magnetic current Id.

[0111] For example, the q-axis current Iq is a key element in generating torque in the permanent magnet electric generator 14, and it varies depending on the state of the high-voltage energy storage device 16 and the torque of the permanent magnet electric generator 14. For instance, when the q-axis current Iq is low due to the charging and discharging state of the high-voltage energy storage device 16, suppression of the q-axis current Iq is ineffective.

[0112] Therefore, specifically through the field weakening control of the MG control unit 15, the suppression of the induced electromotive force E at high speeds is achieved by controlling the field weakening current (d-axis current) Id. In particular, the induced electromotive force E is controlled by Id. Lω inhibition.

[0113] In a permanent magnet electric generator 14 configuration where the number of magnetic poles 142a is greater than 2 / 3 of the number of teeth 141T, the angular velocity ω, expressed in electrical angles, relative to the mechanical rotational speed of the rotor 142 is greater than, for example, in a configuration where the number of magnetic poles is less than or equal to 2 / 3 of the number of teeth.

[0114] Figure 1 Part (f) shows the reactance Lω in this embodiment. As a comparative example, the reactance (Lω)' in a configuration where the number of magnetic poles is less than or equal to 2 / 3 of the number of teeth is shown. Figure 1 As shown in part (f), in a configuration where the number of magnetic poles 142a is greater than 2 / 3 of the number of teeth 141T, the reactance Lω in the suppression component L·ω·Id of the field weakening control is greater than the reactance (Lω)' in a configuration including fewer magnetic poles. Figure 1 (Y1 in part (f)). Therefore, in the permanent magnet electric generator 14 in which the number of magnetic poles 142a is greater than 2 / 3 of the number of teeth 141T, a higher level of terminal voltage suppression is achieved through field weakening control.

[0115] Figure 1Part (g) shows the magnetic weakening current Id in this embodiment. As a comparative example, if a low voltage Vlow is used as the power supply for control, a magnetic weakening current Id' will be obtained, as shown by the dashed line.

[0116] The field-weakening current Id is a component of the current controlled by the MG control unit 15. The MG control unit 15 controls the field-weakening current Id to a target value corresponding to the desired suppression level. The field-weakening current Id flows in a manner that impedes the impedance Z of the winding 141W. As described above, the reactance L·ω contained in the impedance Z of the winding 141W increases with the increase of the angular velocity ω.

[0117] Within a controllable range, the control unit controls the field-weakening current Id so that, regardless of changes in impedance Z, the field-weakening current Id remains at a target value corresponding to suppression. For example, the control unit executes control by using the on-time duty cycle as the command value for the current.

[0118] For example, such as Figure 1 As shown by the dashed line in section (g), the field-weakening current Id' is controlled to a target value corresponding to the suppression of the induced electromotive force increasing with increasing rotational speed N. However, the command value used for control, such as the duty cycle, reaches its upper limit at high rotational speeds and cannot be increased further. The current Id'max at the upper limit of the command value is based on the low voltage Vlow used as the power supply and the impedance Z. If the rotational speed increases after the command value reaches its upper limit, the impedance Z increases, and the command value remains at the upper limit.

[0119] The control unit according to this embodiment uses a high voltage Vhigh as a power supply to perform field weakening control. Therefore, for example, as Figure 1 As shown by the solid line in section (g), the maximum value Idmax of the provided field-weakening current Id can be increased by controlling it. Therefore, the field-weakening current Id can be controlled to maintain the field-weakening current Id at the target value by overcoming the increase in impedance Z caused by the increase in reactance L·ω. That is, even in a configuration where the number of magnetic poles 142a is greater than 2 / 3 of the number of teeth 141T, which leads to an increase in reactance L·ω, the field-weakening current Id of the motor 11 of the straddle vehicle 10 can be maintained at the target value at high speeds (arrow Y2).

[0120] As described above, when the number of magnetic poles 142a is greater than 2 / 3 of the number of teeth 141T, a high voltage is used as the power source to perform field weakening control on the permanent magnet electric generator 14. This configuration allows for a higher level of voltage suppression through field weakening control. Furthermore, this configuration produces a synergistic effect, enabling voltage suppression to take effect at higher engine speeds (arrow Y1 and the level of higher speed indication increase).

[0121] As a result, voltage fluctuations can be reduced over a wide speed range from low to high speeds of the engine 11 of the motorcycle 10. This reduces the variation in voltage supplied from the permanent magnet electric generator 14 to the high-voltage power supply system 13 as the engine speed changes. Therefore, a high voltage with less fluctuation can be used to charge the high-voltage energy storage device 16 over a wide speed range of the engine 11 of the motorcycle 10 without requiring a reduction mechanism such as a belt or chain for the engine 11. Furthermore, the power from the high-voltage energy storage device 16 can be used to control the assistance of the permanent magnet electric generator 14 to the engine 11 over a wide speed range of the engine 11 of the motorcycle 10.

[0122] Therefore, in the motorcycle 10 according to this embodiment, the synergistic effect of enabling higher levels of voltage suppression to take effect at higher speeds through field weakening control allows voltage fluctuations to be reduced over a wide speed range (including high speeds) of the engine 11 of the motorcycle 10, and the resulting voltage is used to charge the high-voltage energy storage device 16. Furthermore, the power from the high-voltage energy storage device 16 can be used to control engine assistance via the permanent magnet electric generator 14 over a wide speed range of the engine 11 of the motorcycle 10. Thus, the high-voltage hybrid power system HV is compact and lightweight, and adaptable to the speed range of the engine 11 of the motorcycle 10.

[0123] When the number of magnetic poles 142a is greater than 2 / 3 of the number of teeth 141T, the effect of using high voltage as a power source to perform field weakening control on the permanent magnet electric generator 14 can be demonstrated in power generation and electric operation.

[0124] Figure 2 It is shown schematically. Figure 1 The diagram illustrates the role of field weakening control in a permanent magnet electric generator. Figure 2 Part (a) shows the relationship between the maximum output torque characteristics and output power characteristics and rotational speed during electric operation. The output power of an electric generator during electric operation is mechanical, while the output power during generator operation is electrical. An electric generator is a device that converts mechanical power into electrical power.

[0125] Reference Figure 2 Part (a) below first describes an example of the characteristics during electric operation, wherein the permanent magnet electric generator 14 is used as an electric motor.

[0126] In this embodiment, the MG control unit 15 performs field weakening control. In field weakening control, the MG control unit 15 supplies current to the winding 141W, causing a magnetic field to be generated in the opposite direction to the magnetic field generated by the magnetic pole 142a that generates the induced electromotive force. This is equivalent to weakening the magnetic force of the magnetic pole 142a. Therefore, a larger current contributing to torque can be supplied to the winding 141W at the maximum output speed NmaxP of the engine 11.

[0127] It should be noted that the maximum output speed NmaxP refers to the speed at which engine 11 produces its maximum output, and is one of the indicators representing the usable speed range of engine 11. The upper limit speed Na of engine 11 is higher than the maximum output speed NmaxP.

[0128] More specifically, as a field weakening control, the MG control unit 15 provides a d-axis current that contributes to the magnetic flux in the opposite direction. Figure 2 The upper right portion of section (a) shows a voltage vector diagram that represents the relationship between voltages during electric operation at the maximum output speed NmaxP of engine 11.

[0129] As a result of the field weakening control, the voltage Vt at the output switching section of the MG control unit 15 is equal to the high voltage Vhigh of the high voltage power supply system 13. Specifically, the voltage Vt obtained by combining the induced electromotive force E with 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 is equal to the high voltage Vhigh of the high voltage power supply system 13. It should be noted that R represents the resistance of the winding 141W, and L represents the inductance of the winding 141W.

[0130] In this configuration, at the maximum output speed NmaxP, the MG control unit 15 uses the voltage of the high-voltage power supply system 13 to enable the permanent magnet electric generator 14 to output torque for rotating the crankshaft 11a. Figure 2 In the example shown, even at a speed Na higher than the maximum output speed NmaxP of the engine 11, the permanent magnet electric generator 14 is still able to output electric operating power.

[0131] The number of magnetic poles 142a in the permanent magnet electric generator 14 is greater than 2 / 3 of the number of teeth 141T. In this configuration, the angular velocity ω of the electrical angle of the permanent magnet electric generator 14 operating as a starter generator is greater than, for example, the angular velocity in a configuration where the number of magnetic poles is less than or equal to 2 / 3 of the number of teeth 141T. Therefore, field weakening control is more effective. Furthermore, since the number of magnetic poles 142a is greater than 2 / 3 of the number of teeth 141T, the size of each magnetic pole 142a is smaller. Therefore, the magnetic flux generated by the magnetic poles 142a is more easily weakened by the magnetic field of the winding 141W through which the d-axis current flows. Therefore, at the maximum output speed NmaxP, the output torque Ta of the permanent magnet electric generator 14 is higher than the output torque Tc in a configuration where the number of magnetic poles is less than or equal to 2 / 3 of the number of teeth 141T.

[0132] The output power Pma of the permanent magnet electric generator 14 depends on the product of the output torque and the rotational speed. Even at the maximum output speed NmaxP, the permanent magnet electric generator 14 under field weakening control can provide sufficient output power Pma.

[0133] Therefore, the permanent magnet electric generator 14, which is powered by the high-voltage energy storage device 16 via the high-voltage power supply system 13, can apply sufficient driving force to the crankshaft 11a over a wide speed range of the engine 11, including the maximum output speed NmaxP. Furthermore, the permanent magnet electric generator 14 can use power from the high-voltage energy storage device 16, which operates at high voltage, to assist the engine over a wide speed range of the engine 11.

[0134] Reference Figure 2 Part (b) below describes an example of the characteristics during power generation, in which the permanent magnet electric generator 14 is used as a generator.

[0135] Figure 1 In part (b), the solid line Pma represents the output power. During the power generation of the permanent magnet electric generator 14, the effect of the reactance L·ω of the winding 141W comes into play.

[0136] The MG control unit 15 generates electricity from the permanent magnet electric generator 14, while simultaneously using high voltage as a power source to perform field weakening control.

[0137] The curve representing the output power Pga during power generation has the same characteristics as... Figure 2 The shape in part (a) is basically symmetrical.

[0138] That is, at the maximum output speed NmaxP, the output power Pga of the permanent magnet electric generator 14 under field weakening control is greater than, for example, the output power without field weakening control.

[0139] Therefore, the output power Pga from the permanent magnet electric generator 14 can charge the high-voltage energy storage device 16 over a wide speed range, including the maximum output speed NmaxP. Thus, the permanent magnet electric generator 14 can provide sufficient power for charging the high-voltage energy storage device 16 via the high-voltage power supply system 13.

[0140] It should be noted that by employing vector control as the control method, the MG control unit 15 can easily and independently control the aforementioned d-axis and q-axis currents. However, there are no particular limitations on the field weakening control method performed by the MG control unit 15. The MG control unit 15 can perform field weakening control by adjusting the current receiving time of each phase of the winding 141W.

[0141] According to this embodiment, the permanent magnet electric generator 14 can operate within a speed range from low to high. The permanent magnet electric generator 14 can operate within a wide speed range, including the maximum output speed NmaxP.

[0142] According to this embodiment, voltage fluctuations generated can be reduced over a wide speed range from low to high speeds of the engine 11 of the motorcycle 10. This reduces the variation in voltage supplied from the permanent magnet electric generator 14 to the high-voltage power supply system 13 as the speed changes. Therefore, a high voltage with less fluctuation can be used to charge the high-voltage energy storage device 16 over a wide speed range of the engine 11 of the motorcycle 10 without requiring a reduction mechanism such as a belt or chain for the engine 11.

[0143] Therefore, in the motorcycle 10 according to this embodiment, the synergistic effect of enabling higher levels of voltage suppression to take effect at higher speeds through field weakening control can reduce voltage fluctuations over a wide speed range (including high speeds) of the engine 11 of the motorcycle 10, and use the resulting voltage to charge the high-voltage energy storage device 16. Furthermore, the power from the high-voltage energy storage device 16 can be used to control engine assistance via the permanent magnet electric generator 14 over a wide speed range of the engine 11 of the motorcycle 10. Therefore, the high-voltage hybrid power system HV is compact and lightweight, and can adapt to the speed range of the engine 11 of the motorcycle 10.

[0144] Figure 3 It shows Figure 1 The diagram shows the current flow in a high-voltage hybrid power system. Figure 3 Part (a) shows the high-voltage energy storage device in the charging state. Figure 3 Part (b) shows the high-voltage energy storage device in the state of discharging.

[0145] like Figure 3As shown in section (a), when an acceleration request is input during engine 11 operation, high-voltage power is supplied from permanent magnet electric generator 14 via MG control unit 15 and high-voltage power supply system 13 to high-voltage energy storage device 16. Therefore, the high-voltage energy storage device is charged.

[0146] like Figure 3 As shown in section (b), when the high-voltage energy storage device 16 is discharging, the permanent magnet electric generator 14 receives the electricity discharged from the high-voltage energy storage device 16 to apply torque to the crankshaft 11a via electric operation. In other words, the permanent magnet electric generator 14 can assist the engine 11 without a secondary battery operating at high voltage. This configuration enables the miniaturization of the engine 11. Therefore, further reduction in the size and weight of the high-voltage hybrid power system HV of the motorcycle 10 can be achieved, while minimizing the reduction in torque or power transmitted to the drive wheels 12a.

[0147] [Second Embodiment] Figure 4 This is a block diagram illustrating the second embodiment. Figure 4 Part (a) is a block diagram showing the current in the straddle vehicle 10 when the engine is running. Figure 4 Part (b) is a block diagram showing the current in the straddle vehicle 10 when it is in a charging state.

[0148] Figure 4 The illustrated straddle-type vehicle 10 includes a starter motor 21 for starting the engine 11. For example, the starter motor 21 drives the crankshaft 11a when the engine is started. The starter motor 21 operates at a low voltage from the low-voltage power supply system 17 to start the engine 11 without requiring electric operation by the permanent magnet electric generator 14. The starter motor 21 operates at a low voltage from the discharge of a low-voltage battery 22 connected to the low-voltage power supply system 17.

[0149] These are the main differences from the first embodiment. The following mainly describes the differences from the first embodiment. Elements that are the same as those in the first embodiment are given the same reference numerals as those in the first embodiment, and their descriptions are omitted.

[0150] The straddle-type vehicle 10 according to this embodiment includes a starter motor 21 that operates at low voltage to start the engine 11. Therefore, even if the permanent magnet electric generator 14 does not have the function of starting the engine 11, the engine 11 can still be started.

[0151] For example, such as Figure 4As shown in part (a), 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 uses the power from the low-voltage battery 22 to start the engine 11.

[0152] After the engine 11 starts, the permanent magnet electric generator 14 is driven by the engine 11 and generates electricity. For example... Figure 4 As shown in section (b), the current generated by the permanent magnet electric 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 electric generator 14 into a low voltage. The current supplied via the DC-DC converter 18 is stored in the low-voltage battery 22.

[0153] Typically, the motor used to start the engine 11 often needs to output sufficiently high torque to start the engine 11. Therefore, for example, it is usually necessary to increase the magnetic flux of the magnet. However, in this embodiment, the permanent magnet electric generator 14 omits the starting function, increasing the degree of configuration freedom, for example, allowing the use of a magnet with weaker magnetic flux to form the magnetic poles 142a.

[0154] Therefore, the permanent magnet electric generator 14 can be configured to output power corresponding to the high-voltage power supply system 13 within a range closer to the speed dynamic range of the engine 11. As a result, a further reduction in the size and weight of the high-voltage hybrid power system HV of the motorcycle 10 can be achieved.

[0155] List of reference numerals 10 straddle-mounted vehicles 11 engine 11a crankshaft 12a drive wheel 13 High Voltage Power Supply System 14 permanent magnet electric generator 15MG control unit 16 High-voltage energy storage devices 17 Low Voltage Power Supply System 21 starter motor 141 stator 141T teeth 141W winding 142 rotor 142a magnetic pole

Claims

1. A straddle-type vehicle, comprising: An engine having a crankshaft and configured to output torque via said crankshaft; A drive wheel configured to receive at least a portion of the torque output from the engine and mechanically transmitted to the drive wheel to drive the straddle vehicle; A high-voltage power supply system configured to operate at a high voltage higher than the low voltage of a low-voltage power supply system, wherein the low-voltage power supply system has a low-voltage battery connected to the low-voltage power supply system. A permanent magnet electric generator configured to transmit power to and from the high-voltage power supply system, apply torque to the drive wheel by electric operation, and generate power by receiving torque from the engine or the drive wheel, the permanent magnet electric generator including a stator and a rotor, the stator having a plurality of teeth arranged in a circumferential direction and a winding wound on each of the plurality of teeth, the rotor having magnetic poles and being disposed on a rotating shaft coaxial with the crankshaft and rotating at the same speed as the crankshaft; An MG control unit, electrically connected to the high-voltage power supply system and also electrically connected to the permanent magnet electric generator, is configured to control the electric operation and power generation of the permanent magnet electric generator; and A high-voltage energy storage device electrically connected to the high-voltage power supply system and configured to charge and discharge at the high voltage, which is higher than the low voltage; wherein The MG control unit uses a high voltage, higher than the low voltage of the low-voltage battery, as a power source to perform field weakening control on the permanent magnet electric generator, which includes a rotor that rotates at the same speed as the motor of the motorcycle, and wherein the number of magnetic poles is greater than 2 / 3 of the number of teeth, such that the voltage suppression level achieved by the field weakening control increases due to the increased reactance caused by the greater number of magnetic poles of the permanent magnet electric generator, and such that by using the field weakening control powered by the high voltage, the increased reactance at high speeds of the motorcycle's motor is overcome, and the current component for the field weakening control is supplied to the winding.

2. The straddle-type vehicle according to claim 1, further comprising: A starter motor, configured to operate at the low voltage of the low-voltage power supply system, to start the engine without requiring the permanent magnet electric generator to operate electrically, wherein... The MG control unit uses a high voltage, higher than the low voltage of the low-voltage battery, as a power source to perform the field weakening control on the permanent magnet electric generator including the rotor. The low voltage of the low-voltage battery is used for the operation of the starter motor. The rotor rotates at the same speed as the engine of the straddle vehicle, and the number of magnetic poles is greater than 2 / 3 of the number of teeth.

3. The straddle-type vehicle according to claim 1 or 2, wherein The high-voltage energy storage device is a capacitor or a secondary battery. The permanent magnet electric generator receives power from the capacitor to apply torque to the crankshaft via electric operation, and The MG control unit uses the high voltage of the high-voltage power supply system connected to the capacitor or the secondary battery as a power source to perform the field weakening control on the permanent magnet electric generator including the rotor. The high voltage is higher than the low voltage of the low-voltage battery. The rotor rotates at the same speed as the engine of the straddle vehicle, and the number of magnetic poles is greater than 2 / 3 of the number of teeth.

4. The straddle-type vehicle according to claim 3, wherein The secondary battery is a high-current charging drive lithium-ion battery that meets the specifications for both high-current charging and high-current discharging. The permanent magnet electric generator receives power from the high-current-chargeable drive lithium-ion battery to apply torque to the crankshaft via electric operation. The high-current discharge specification is that, for a charging capacity of 2.5Ah, the battery can discharge at a maximum operating current corresponding to 10C or higher. The high-current charging specification is that, for a charging capacity of 2.5Ah, the battery can be charged at a maximum operating current corresponding to a rate of 10C or higher; and The MG control unit uses the high voltage of the high-voltage power supply system connected to the high-current rechargeable drive lithium-ion battery as a power source to perform the field weakening control on the permanent magnet electric generator including the rotor. The high voltage is higher than the low voltage of the low-voltage battery. The rotor rotates at the same speed as the engine of the straddle vehicle, and the number of magnetic poles is greater than 2 / 3 of the number of teeth.

Images