JP2023170540A - Switching control method and switching control device - Google Patents

Abstract

To properly use a diffusion mode and a basic mode in switching control of an inverter.SOLUTION: A vehicle includes a power generator, a drive motor that is operated with power generated by the power generator, and an inverter that includes a first switching device for converting DC power supplied to the drive motor to AC power and a second switching device for converting power generated by the power generator to DC power. A switching control method for the second switching device is performed by a second switching device control unit. In the method, a basic mode of keeping a carrier frequency at a prescribed basic value is executed when the temperature difference between a cooling water temperature at an inverter inlet of a cooling water path through which cooling water flows through the inverter, the drive motor, and the power generator in this order, and the temperature of a stator coil of the power generator is equal to or greater than a first threshold, and a diffusion mode of changing the carrier frequency in a prescribed switching cycle is executed when the temperature difference is less than the first threshold.SELECTED DRAWING: Figure 1

Description

The present invention relates to a switching control method and a switching control device.

Patent Document 1 discloses one aspect of PWM (Pulse Width Modulation) control for an inverter as a switching device that adjusts power supplied to a three-phase AC motor.

In particular, in the above literature, the frequency of the carrier wave used for PWM control (carrier frequency ) switching control has been proposed in which the control mode of the carrier frequency is switched between a spread mode in which the carrier frequency is changed (spread) at a predetermined period and a fundamental mode in which the carrier frequency is fixed at a predetermined basic period.

By setting the control mode to the diffusion mode, noise caused by an increase in the ripple current of the inverter is suppressed. On the other hand, by setting the control mode to the basic mode, switching losses are reduced and optimal energy efficiency is ensured. That is, in the above-mentioned document, a scene in which noise suppression should be prioritized and a scene in which energy efficiency should be prioritized are separated according to the operating point of the drive motor, and an appropriate switching control mode is set for each scene.

JP 2021-136738A

In recent years, a type of vehicle (so-called series hybrid vehicle) in which the drive power of a drive motor is provided by the power generated by a generator has become popular. In this type of vehicle, noise is also generated by the operation of the generator, so it is desirable to set the control mode to the diffusion mode in order to appropriately suppress the noise. However, the operating point of the generator is basically determined independently of the driving state of the vehicle. For this reason, even with reference to the operating point of the generator, it is difficult to appropriately determine a scene where the noise of the generator becomes a problem (for example, a scene where background noise during driving is low). That is, in the conventional control described above, when assuming switching control in a series hybrid vehicle equipped with the above-mentioned generator, there is a problem in that it is not possible to realize appropriate separation between the basic mode and the diffusion mode depending on the scene.

Therefore, an object of the present invention is to provide a switching control method and a switching control device that can realize appropriate separation between the diffusion mode and the fundamental mode even when applied to a series hybrid vehicle.

According to an aspect of the present invention, there is provided a generator, a drive motor for driving that operates with the power generated by the generator, a first switching device that converts power supplied to the drive motor from DC power to AC power, and a power generator. In a vehicle equipped with an inverter that includes as a component a second switching device that converts AC power generated by the generator into DC power, the power of the generator is executed by a second switching device control unit that controls the second switching device. A switching control method is provided for adjusting the carrier frequency of a carrier wave used for PWM control. In this method, the water inlet temperature, which is the cooling water temperature at the inlet to the inverter, and the stator coil temperature, which is the temperature of the stator coil of the generator, of the cooling water channel through which cooling water flows in the order of the inverter, drive motor, and generator are obtained. However, when operating the generator, if the temperature difference between the waterway inlet temperature and the stator coil temperature is greater than or equal to a preset first threshold, a basic mode is executed to maintain the carrier frequency of the carrier wave at a predetermined basic value. However, if the temperature difference is smaller than the first threshold, a spreading mode is executed in which the carrier frequency of the carrier wave is changed at a predetermined switching cycle.

According to another aspect of the present invention, there is provided a generator, a drive motor for running that operates using the generated power of the generator, a first switching device that converts power supplied to the drive motor from DC power to AC power, and An inverter that includes a second switching device as a component that converts alternating current power generated by the generator into direct current power, and is mounted on a vehicle and adjusts the carrier frequency of a carrier wave used for PWM control to adjust the power of the generator. A switching control device is provided. This device obtains the water channel inlet temperature, which is the cooling water temperature at the inlet to the inverter, and the stator coil temperature, which is the temperature of the stator coil of the generator, of the cooling water channel through which cooling water flows in the order of the inverter, drive motor, and generator. an acquisition unit that maintains the carrier frequency of the carrier wave at a predetermined basic value when the temperature difference between the waterway inlet temperature and the stator coil temperature is greater than or equal to a preset first threshold value when operating the generator; and a control mode determining unit that executes a spread mode in which the carrier frequency of the carrier wave is changed at a predetermined switching cycle when the temperature difference is smaller than the first threshold.

According to each of the above aspects, it is possible to provide a switching control method and a switching control device that can realize appropriate separation between the diffusion mode and the basic mode even when applied to a series hybrid vehicle.

FIG. 1 is a configuration diagram of a vehicle control system in which the switching control method of the first embodiment is executed. FIG. 2 is a flowchart illustrating the process of determining the control mode of the generator in the first embodiment. FIG. 3 is a configuration diagram of a vehicle control system in which the switching control method of the second embodiment is executed. FIG. 4 is a flowchart illustrating the process of determining the control mode of the generator in the second embodiment. FIG. 5 is a flowchart illustrating the process of determining the control mode of the generator in the third embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

[First embodiment]
FIG. 1 is a configuration diagram of a vehicle control system 100 in which the switching control method of this embodiment is executed. Note that the vehicle control system 100 of the present embodiment is a hybrid vehicle ( For example, it is assumed that it will be applied to series hybrid vehicles).

The vehicle control system 100 mainly includes a drive motor 1, a generator 2, a battery 3, a power converter A, and a cooling device 30.

The drive motor 1 is composed of a three-phase AC motor, and operates (powered operation or regenerative operation) by receiving power from a battery 3 or a generator 2 to achieve a desired driving force (braking force). Driving force (braking force) is applied to the drive wheels of the vehicle through a predetermined transmission mechanism that does not.

The generator 2 is constituted by a three-phase AC motor, receives driving force generated by an engine (not shown), generates electric power for driving the drive motor 1, and supplies it to the battery 3 or the drive motor 1. Note that the generator 2 may be configured to receive power from the battery 3 as appropriate to drive the engine. Thereby, the generator 2 can be used to perform cranking (motoring), for example, when starting the engine.

The cooling device 30 includes a cooling path 31 provided in the power converter A, a circulation path 34 that communicates with the inlet and outlet of the cooling path 31 to the power converter A, a pump 33 that circulates cooling liquid, and a cooling path 34 that communicates with the inlet and outlet of the cooling path 31 to the power converter A. A radiator 32 for exchanging heat between the liquid and the outside air is provided. In the circulation path 34, a drive motor 1, a generator 2, and a radiator 32 are arranged in this order from the outlet of the power converter A of the cooling path 31.

When the cooling liquid flows into the cooling path 31 from the circulation path 34, it first cools the first switching device 10, then cools the second switching device 20, and returns to the circulation path 34 again. The coolant that has returned to the circulation path 34 cools the drive motor 1, then the generator 2, radiates heat to the outside air by the radiator 32, and flows into the power converter A again.

The power conversion device A is mainly configured by a first switching device 10, a second switching device 20, a first switching device control section 51, and a second switching device control section 52. Note that in the following description, the first switching device 10 and the second switching device 20 may be collectively referred to as an inverter.

The first switching device 10 converts DC power into AC power and supplies the AC power to the drive motor 1 . The second switching device 20 converts AC power generated by the generator 2 into DC power.

The first switching device control unit 51 receives a torque command value from a vehicle controller (not shown), controls the first switching device 10 based on the torque command value, and causes the drive motor 1 to generate a drive torque.

The second switching device control unit 52 receives a rotation speed command value from the vehicle controller, controls the second switching device 20 based on the rotation speed command value, and causes the generator 2 to generate electricity.

The power converter A also includes a water temperature sensor 40 that detects the temperature of the cooling fluid at the inlet portion of the cooling path 31 (channel inlet temperature tw), and a first motor temperature sensor 1a that detects the temperature of the coil portion of the drive motor 1. and a second motor temperature sensor 2a that detects the temperature of the coil portion of the generator 2. The inlet portion of the cooling path 31 herein refers to the portion of the cooling path 31 before cooling the first switching device 10, in other words, the inlet portion of the inverter. Note that each temperature sensor may be a thermistor.

The water temperature detection unit 51a of the first switching device control unit 51 and the water temperature detection unit 52a of the second switching device control unit 52 receive the output signal of the water temperature sensor 40, and acquire the waterway inlet temperature tw based on the output signal. . The coil temperature detection unit 51b of the first switching device control unit 51 receives the output signal of the first motor temperature sensor 1a, and acquires the stator coil temperature tm1 of the drive motor 1 based on the output signal. The coil temperature detection unit 52b of the second switching device control unit 52 receives the output signal of the second motor temperature sensor 2a, and acquires the stator coil temperature tm2 of the generator 2 based on the output signal.

The second switching device control unit 52 calculates a temperature difference Δt1 between the waterway inlet temperature tw detected by the water temperature detection unit 52a and the coil temperature detection unit 52b and the stator coil temperature tm2 of the generator 2 in the temperature difference calculation unit 52c. calculate. Then, the carrier diffusion determining section 52d determines whether or not to execute the diffusion mode based on the temperature difference. The details of this determination will be described later. In the above configuration, the water temperature detection section 52a and the coil temperature detection section 52b of the second switching device control section 52 correspond to the acquisition section, and the carrier diffusion determination section 52d corresponds to the control mode determination section.

The battery 3 is an in-vehicle DC power source configured with, for example, a lithium ion secondary battery.

In the vehicle control system 100 as described above, the generator 2 is basically driven with the carrier frequency of the second switching device 20 fixed (basic mode) in order to increase switching efficiency. However, when installed in a series hybrid vehicle, a situation may arise in which power is generated while the vehicle is stopped. In this situation, the second switching device 20 will perform switching to drive the generator 2, but since the vehicle is stopped, if the vehicle is driven in the basic mode, the noise and vibration caused by the switching will be transmitted to the occupants of the vehicle. may cause discomfort. As a method for reducing such sounds and vibrations, changing the carrier frequency of the second switching device 20 at a predetermined period (diffusion mode) is known.

However, when the controlled object is the generator 2, it is necessary to detect that the vehicle is stopped in order to switch from the basic mode to the diffusion mode. In a typical vehicle, the shift range of the transmission, the vehicle speed, etc. are detected by a sensor, and these are sent and received between various controllers as signals on CAN communication, so the second switching device control section 52 detects the signals. Based on this, it is possible to determine whether the vehicle is stopped or not. However, in a typical vehicle, the controller (here, the second switching device control section 52) that controls the generator 2 is not configured to refer to signals of the shift range or vehicle speed. Furthermore, when referring to a signal on CAN communication, reliability is generally ensured by executing a control routine that determines that the signal is not due to false detection or misdiagnosis. Therefore, if the second switching device control unit 52 is configured to refer to signals on CAN communication, the system becomes complicated and the load on the CPU increases.

Therefore, in this embodiment, by the method described below, it is possible to detect that the vehicle is stopped and switch to the diffusion mode without complicating the system as described above.

The cooling device 30 of this embodiment is configured such that the coolant cooled by the radiator 32 cools the inverter, the drive motor 1, and the generator 2 in this order. Therefore, when the drive motor 1 is driven and the vehicle is running, the temperature of the coolant at the inlet of the generator 2 increases by the amount of heat removed from the inverter and the drive motor 1, so The heat removal effect is decreasing. Therefore, the temperature of the generator 2 becomes higher than when the vehicle is stopped, and the temperature tm2 of the stator coil portion of the generator 2 also becomes higher than when the vehicle is stopped. In other words, the temperature difference between the waterway inlet temperature tw and the stator coil temperature tm2 of the generator 2 is larger when the vehicle is running than when the vehicle is stopped.

Therefore, the temperature difference that can be obtained when the vehicle is stopped is determined through experiments or the like, a first threshold value is set for the temperature difference, and if the temperature difference is smaller than the first threshold value, it is determined that the vehicle is stopped. In other words, the amount of temperature increase due only to the loss of the second switching device 20 and the generator 2 is set as the first threshold value, and if the temperature difference is larger than the first threshold value, the drive motor 1 is being driven, and if it is smaller than the first threshold value, the drive motor 1 is being driven. It is determined that This makes it possible to determine whether the vehicle is stopped or not using a simple method without referring to signals on CAN communication.

FIG. 2 is a flowchart illustrating the process of determining the control mode of the generator 2, which is executed by the second switching device control unit 52. Note that the second switching device control unit 52 repeatedly executes the flowchart shown in FIG. 2 at every predetermined control period.

In step S1, the water channel inlet temperature tw and stator coil temperature tm2 are read. Specifically, the water temperature detection section 52a reads the output signal of the water temperature sensor 40, and the coil temperature detection section 52b reads the output signal of the second motor temperature sensor 2a.

In step S2, the temperature difference calculation unit 52c calculates the temperature difference Δt1 by subtracting the waterway inlet temperature tw from the stator coil temperature tm2.

In step S3, the carrier diffusion determination unit 52d uses the temperature difference Δt1 to read the first threshold value tlim1 from a pre-stored map. The map used here is one in which a first threshold value tlim1 of the temperature difference between the waterway inlet temperature tw and the stator coil temperature tm2 is assigned to the operating state (torque and rotation speed) of the generator 2. Generally, the larger the torque and the higher the rotational speed, the higher the temperature of the coil of the generator 2 becomes, and therefore the first threshold value tlim1 also becomes larger.

In step S4, the carrier diffusion determining unit 52d determines whether the temperature difference Δt1 is smaller than the first threshold tlim1. If it is smaller, the diffusion mode is executed in step S5a, and if not, the basic mode is executed in step S5b. Execute.

As described above, this embodiment includes a generator 2, a drive motor 1 for driving that operates with the generated power of the generator 2, and a first switching system that converts the power supplied to the drive motor 1 from DC power to AC power. A second switching device control unit 52 that controls the second switching device 20 in a vehicle that includes the device 10 and an inverter that includes as a component the second switching device 20 that converts AC power generated by the generator 2 into DC power. Provided is a switching control method that adjusts the carrier frequency of a carrier wave used for PWM control that adjusts the power of the generator 2, which is executed by the present invention. In this method, the water channel inlet temperature tw, which is the cooling water temperature at the inlet to the inverter of the cooling device 30 through which the cooling water flows in the order of the inverter, the drive motor 1, and the generator 2, and the stator coil temperature tw, which is the temperature of the stator coil of the generator 2, are determined. When obtaining the coil temperature tm2 and operating the generator 2, if the temperature difference Δt1 between the waterway inlet temperature tw and the stator coil temperature tm2 is equal to or higher than a preset first threshold tlim1, execute the basic mode, If the temperature difference Δt1 is smaller than the first threshold tlim1, the diffusion mode is executed. The first threshold value tlim1 of this embodiment is the temperature difference between the waterway inlet temperature tw and the stator coil temperature tm2, which occurs due to loss in the second switching device 20 and the generator 2 when the drive motor 1 is stopped. .

With this, it is possible to determine whether or not the vehicle is stopped using simple logic without referring to signals on CAN communication, thereby avoiding complication of the system and increase in load on the CPU.

[Second embodiment]
FIG. 3 is a configuration diagram of a vehicle control system 100 in which the switching control method of this embodiment is executed. Note that the vehicle control system 100 of this embodiment is also assumed to be applied to a hybrid vehicle (for example, a series hybrid vehicle) similarly to the first embodiment.

The vehicle control system 100 of the present embodiment is similar to the first embodiment in that it includes a first rotation sensor 1b that detects the rotation speed of the drive motor 1 and a current sensor 10a that detects the drive current of the first switching device 10. This is a difference from the vehicle control system 100 shown in FIG. Further, the first switching device control section 51 of this embodiment is different from the first switching device control section 51 of the first embodiment in that it includes a current detection section 51c and a rotation speed detection section 51d.

The current detection unit 51c receives the output signal of the current sensor 10a, and obtains the drive current im1 of the first switching device 10 based on the output signal. The rotation speed detection unit 51d receives the output signal of the first rotation sensor 1b, and acquires the rotation speed nm1 of the drive motor 1 based on this. These drive current im1 and rotation speed nm1 are transmitted to the second switching device control section 52.

By the way, when the diffusion mode is used, the above-mentioned problems of sound and vibration are solved, but the power generation efficiency is lower than that of the basic mode. In other words, it is desirable to execute the diffuse mode only in situations where it really needs to be executed, and to execute the basic mode in situations where sound and vibration are not a problem even in the basic mode. Therefore, in this embodiment, when the temperature difference Δt1 is smaller than the first threshold value tlim1, a determination is further made to confirm that the vehicle is stopped, and if it is also determined that the vehicle is stopped, the diffusion Run mode.

FIG. 4 is a flowchart illustrating the process of determining the control mode of the generator 2, which is executed by the second switching device control unit 52. Note that the second switching device control unit 52 repeatedly executes the flowchart shown in FIG. 2 at every predetermined control period.

Steps S1 to S4 in FIG. 4 are similar to steps S1 to S4 in FIG. 2, so the explanation will be omitted.

If the temperature difference Δt1 is greater than or equal to the first threshold tlim1 in step S4, the carrier diffusion determining unit 52d executes the basic mode in step S5b, as in the first embodiment, but if it is smaller than the first threshold tlim1, step S4a Execute the process.

In step S4a, the carrier diffusion determining unit 52d determines whether the rotational speed nm1 of the drive motor 1 is zero. If it is zero, it executes the process of step S4b, and if it is not zero, it executes the process of step S5b.

In step S4b, the carrier diffusion determination unit 52d determines whether the drive current im1 of the drive motor 1 is zero. If it is zero, the diffusion mode is executed in step S5a, and if it is not zero, the process in step S5b is executed.

As described above, in the flowchart of FIG. 4, if the temperature difference Δt1 is smaller than the first threshold tlim1, it is further determined whether the rotational speed nm1 of the drive motor 1 and the drive current im1 are zero. Then, the diffusion mode is executed when the rotational speed nm1 and the drive current im1 are zero, and the basic mode is executed when at least one of them is not zero. This makes it possible to more accurately determine whether the vehicle is stopped or not. Note that instead of determining whether the drive current of the drive motor 1 is zero, it may be determined whether the motor torque command value qm1 of the drive motor 1 is zero. In this case, the current sensor 10a becomes unnecessary, and the second switching device control section 52 is configured to receive the motor torque command value qm1 from a vehicle controller (not shown).

As described above, in this embodiment, the rotation speed nm1 of the drive motor 1 and the drive current im1 or the torque command value are acquired, and when the temperature difference Δt1 is less than or equal to the first threshold value tlim1, the rotation speed nm1 is further increased. It is determined whether the drive current im1 or the torque command value is zero. If the rotational speed nm1 is zero and the drive current im1 or torque command value qm1 is zero, the diffusion mode is executed, and if the rotational speed nm1 is not zero or the drive current im1 or torque command value qm1 is not zero, the basic Run mode. This makes it possible to more accurately determine whether the vehicle is stopped or not.

[Third embodiment]
The configuration of a vehicle control system 100 in which the switching control method of this embodiment is executed is the same as that of the second embodiment.

In the first embodiment and the second embodiment, the second switching device control unit 52 determines that the drive motor 1 is being driven when the temperature difference Δt1 is greater than or equal to the first threshold tlim1, and executes the basic mode. However, there is a state in which the rotation speed of the drive motor 1 becomes zero even though the drive current flows through the drive motor 1 and the torque command value of the drive motor 1 is greater than zero. A first example of this state is a state where the vehicle is stopped on an uphill road with the travel range selected and the brake pedal depressed. In this state, the drive motor 1 is generating so-called creep torque, so the torque command value and drive current are not zero, but the rotational speed is zero. As a second example, there is a situation where the vehicle does not move forward on a steep uphill road due to insufficient depression of the accelerator pedal or the like. In this state, when the accelerator pedal is depressed, the torque command value and drive current of the drive motor 1 are greater than zero, and the rotation speed becomes zero even though the brake pedal is not depressed (hereinafter, this state is also called the locked state). In the locked state, the drive motor 1 generates heat even if it is not rotating because a drive current flows through it, and the first switching device 10 also generates heat because it is driven to supply current to the drive motor 1. That is, in the locked state, the temperature difference Δt1 is larger than in the stopped state where no drive current flows through the drive motor 1.

The driver's situation in the first example is the same as when the driver is stopped on level ground, and the noise and vibrations caused by switching may cause discomfort to the driver, so the diffusion mode should not be executed. is desirable. On the other hand, in the second example, the driver is concentrating on driving and is not as relaxed as in the first example, so running the basic mode will not cause discomfort to the driver. do not have.

As described above, even if the temperature difference Δt1 is greater than or equal to the first threshold tlim1, there are states in which the diffusion mode is desirable and states in which there is no problem in the basic mode. Therefore, in this embodiment, it is determined whether to perform the diffusion mode or the basic mode using the method described below.

FIG. 5 is a flowchart illustrating the process of determining the control mode of the generator 2, which is executed by the second switching device control unit 52. Note that the second switching device control unit 52 repeatedly executes the flowchart shown in FIG. 2 at every predetermined control period.

Steps S1 to S3 and S4 in FIG. 5 are the same as those in the first and second embodiments, so their explanation will be omitted.

After the process in step S3, the carrier diffusion determination unit 52d reads the second threshold value tlim2 and the threshold value ilim1 of the drive current of the first switching device 10 in step S3a. The second threshold value tlim2 is a threshold value for determining whether or not the lock state is established, and is generated due to losses in the first switching device 10, the second switching device 20, the drive motor 1, and the generator 2 in the lock state. This is the amount of temperature rise. Specifically, the temperature difference Δt1 is used to read from a map stored in advance. The map used here is based on the results of experiments and the like, and is based on the operating conditions (torque and rotational speed) of the drive motor 1 and generator 2, and the second A threshold value tlim2 is assigned. Generally, the larger the torque and the higher the rotational speed, the higher the temperature of the coils of the drive motor 1 and the generator 2 becomes, and therefore the second threshold value tlim2 also becomes larger. The threshold value ilim1 is a value that can be used to determine whether or not the drive motor 1 is being driven, and is, for example, a drive current equivalent to creep torque.

If the carrier diffusion determining unit 52d determines in step S4 that the temperature difference Δt1 is greater than or equal to the first threshold tlim1, it determines in step S4c whether the temperature difference Δt1 is greater than the second threshold tlim2. If the temperature difference Δt1 is larger than the second threshold tlim2, the carrier diffusion determination unit 52d executes the basic mode in step S5b. If the temperature difference Δt1 is less than or equal to the second threshold tlim2, the carrier diffusion determination unit 52d executes the process of step S4a. As explained in FIG. 4, the process in step S4a is a determination as to whether or not the rotation speed nm1 of the drive motor 1 is zero. The carrier diffusion determination unit 52d executes the process of step S4d when the rotational speed nm1 is zero, and executes the basic mode in step S5b when it is not zero.

In step S4d, the carrier diffusion determination unit 52d determines whether the drive current im1 of the first switching device 10 is equal to or greater than the third threshold value ilim1. The carrier diffusion determination unit 52d executes the diffusion mode in step S5a when the drive current im1 is greater than or equal to the third threshold ilim1, and executes the basic mode in step S5b when the drive current im1 is smaller than the third threshold ilim1. .

As described above, in the flowchart of FIG. 5, it is determined whether or not the temperature difference Δt1 is larger than the second threshold value tlim2, that is, whether or not the lock state is established (step S4c), and if it is determined that the lock state is established, the basic mode is selected. (Step S5c). This is because, in the locked state, problems such as noise and vibration caused by switching will not occur even if the basic mode is executed.

Furthermore, even if the temperature difference Δt1 is greater than or equal to the second threshold tlim2, the basic mode is executed unless the rotational speed nm1 of the drive motor 1 is zero (steps S4a, S5b). This is because the fact that the drive motor 1 is rotating means that the vehicle is running, and even if the basic mode is executed, problems of noise and vibration caused by switching will not occur.

Further, even if the temperature difference Δt1 is greater than or equal to the second threshold value tlim2 and the rotational speed nm1 of the drive motor 1 is zero, if the drive current of the drive motor 1 is greater than or equal to the third threshold value ilim1, the basic mode is executed (step S4d, S5b). In this case, as in the locked state, the drive motor 1 is not rotating even though it is being driven, and it can be assumed that the driver is concentrating on driving, so the basic mode is executed. This is because the problem of noise and vibration caused by switching does not occur even if the switch is switched.

Then, if all of the following conditions are satisfied: the temperature difference Δt1 is greater than or equal to the second threshold tlim2, the rotational speed nm1 of the drive motor 1 is zero, and the drive current of the drive motor 1 is smaller than the third threshold ilim1, the diffusion mode is executed. (Steps S4d, S5a). In this case, if the basic mode is executed, noise and vibration problems due to switching will occur, similar to when the vehicle is stopped on level ground, so it is desirable to execute the diffuse mode.

Note that the torque command value of the drive motor 1 may be used instead of the drive current im1 of the drive motor 1 in FIG. In this case, the third threshold value is a torque command value equivalent to creep torque. Since there is a correlation between the drive current and the torque command value, similar results can be obtained no matter which value is used.

As described above, in this embodiment, the rotation speed nm1 of the drive motor 1 and the drive current im1 or the torque command value qm1 are acquired, and when the temperature difference Δt1 is equal to or greater than the first threshold value tlim1, the temperature difference Δt1 is further increased. is larger than a preset second threshold tlim2, determines whether rotation speed nm1 is zero, and determines whether drive current im1 (or torque command value qm1) is larger than a preset third threshold ilim1 (or qlim1). ) or more. When the temperature difference Δt1 is larger than the second threshold tlim2, or when the rotational speed nm1 is not zero, or when the drive current im1 (or torque command value qm1) is greater than or equal to the preset third threshold ilim1 (qlim1), the basic Run mode. On the other hand, when all of the following conditions are satisfied: the temperature difference Δt1 is less than or equal to the second threshold tlim2, the rotational speed nm1 is zero, and the drive current im1 (or torque command value qm1) is smaller than the third threshold ilim1 (or qlim1), the diffusion Run mode. The second threshold value tlim2 is the first switching device 10, the second switching device 20, the drive motor 1, and the generator 2 when the drive current is flowing but the rotation speed of the drive motor 1 is in a locked state. The third threshold value ilim1 is the drive current or creep torque in the creep state.

Thereby, when the vehicle is stopped, it can be determined whether the vehicle is in a normal stopped state due to the drive motor 1 stopping or a locked state. Then, it is possible to execute a mode suitable for each state.

It goes without saying that the present invention is not limited to the embodiments described above, and that various changes can be made within the scope of the technical idea described in the claims.

1 drive motor, 2 generator, 3 battery, 10 first switching device, 20 second switching device, 30 cooling device, 51 first switching device control section, 52 second switching device control section

Claims (6)

A generator, a drive motor for running that operates with the power generated by the generator, a first switching device that converts the power supplied to the drive motor from DC power to AC power, and AC power generated by the generator. an inverter that includes as a component a second switching device that converts DC power into DC power, and a PWM that adjusts the power of the generator, which is executed by a second switching device control unit that controls the second switching device. A switching control method for adjusting a carrier frequency of a carrier wave used for control, the method comprising:
A waterway inlet temperature, which is the cooling water temperature at the inlet to the inverter, of a cooling waterway through which cooling water flows in the order of the inverter, the drive motor, and the generator, and a stator coil temperature, which is the temperature of the stator coil of the generator. Acquired,
When operating the generator,
If the temperature difference between the waterway inlet temperature and the stator coil temperature is equal to or higher than a preset first threshold, executing a basic mode in which the carrier frequency of the carrier wave is maintained at a predetermined basic value;
A switching control method characterized in that, when the temperature difference is smaller than the first threshold, a spreading mode is executed in which the carrier frequency of the carrier wave is changed at a predetermined switching cycle. The switching control method according to claim 1,
The first threshold value is a temperature difference between the waterway inlet temperature and the stator coil temperature, which is caused by a loss in the second switching device and the generator when the drive motor is stopped. . The switching control method according to claim 1 or 2,
Obtaining the rotation speed and drive current or torque command value of the drive motor,
When the temperature difference is less than or equal to the first threshold,
Further, determining whether the rotation speed is zero, and determining whether the drive current or the torque command value is zero,
If the rotational speed is zero and the drive current or the torque command value is zero, executing the diffusion mode;
A switching control method, wherein the basic mode is executed if the rotational speed is not zero, or if the drive current or the torque command value is not zero. The switching control method according to claim 2,
Obtaining the rotation speed and drive current or torque command value of the drive motor,
If the temperature difference is greater than or equal to the first threshold,
Furthermore, it is determined whether the temperature difference is larger than a second preset threshold, whether the rotation speed is zero, and whether the drive current or the torque command value is greater than or equal to a third preset threshold. make a determination, and
When the temperature difference is greater than the second threshold, or when the rotational speed is not zero, or when the drive current or the torque command value is greater than or equal to the third threshold, executing the basic mode;
Switching control that executes the diffusion mode when all of the following conditions are satisfied: the temperature difference is less than or equal to the second threshold, the rotation speed is zero, and the drive current or the torque command value is smaller than the third threshold. Method. The switching control method according to claim 4,
The second threshold value is determined by the first switching device, the second switching device, the drive motor, and the generator when the drive current is flowing but the rotation speed is zero. a temperature difference between the waterway inlet temperature and the stator coil temperature caused by loss;
The switching control method, wherein the third threshold is the drive current or creep torque in a creep state. A generator, a drive motor for running that operates with the power generated by the generator, a first switching device that converts the power supplied to the drive motor from DC power to AC power, and AC power generated by the generator. an inverter that includes as a component a second switching device that converts the power into direct current power; ,
A waterway inlet temperature, which is the cooling water temperature at the inlet to the inverter, of a cooling waterway through which cooling water flows in the order of the inverter, the drive motor, and the generator, and a stator coil temperature, which is the temperature of the stator coil of the generator. an acquisition unit that acquires;
a basic mode in which the carrier frequency of the carrier wave is maintained at a predetermined basic value when the temperature difference between the waterway inlet temperature and the stator coil temperature is greater than or equal to a preset first threshold value when operating the generator; and a control mode determining unit that executes a spread mode in which the carrier frequency of the carrier wave is changed at a predetermined switching cycle when the temperature difference is smaller than the first threshold value. Control device.