JP2002271903A - Vehicle with synchronous motor taken driving source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve gradability of a vehicle which takes a synchronous motor as a driving source. SOLUTION: This vehicle having the synchronous motor taken as the driving source comprises a synchronous motor 3 for driving the vehicle, a torque control means 4 for computing a torque command value of the synchronous motor 3, a current control means 5 for computing a command value of the current to be flowed through the synchronous motor 3 based on the torque command value, and a power converting means 2 for converting DC current of a battery 1 to AC current by switching energizing patterns of a plurality of power devices and supplying the current corresponding to the current command value to the synchronous motor 3. In the vehicle with the synchronous motor taken as the driving source, there is provided an on-hill starting detecting means 5 for detecting on-hill star, which increases the current command value beyond the maximum current in an ordinary service area in the case of detection of the on-hill start.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile using a synchronous motor as a driving source, and more particularly to an automobile having improved climbing performance.

[0002]

2. Description of the Related Art Vehicles such as electric vehicles and hybrid vehicles using a synchronous motor as a driving source are known. In this specification, an automobile using a synchronous motor as a driving source is simply referred to as an "automobile" or an "automobile equipped with a synchronous motor".

When a vehicle equipped with this synchronous motor is used to climb a steep hill, the vehicle is stopped halfway down the hill and then started with the accelerator fully opened from a stopped state or a state of sliding down the hill by its own weight. Sometimes, a car moves forward while generating maximum torque. In such a case, there is no problem with the gradient having a sufficient drive torque, but when the gradient is increased, the time during which the synchronous motor stops generating the maximum torque becomes longer.

In a synchronous motor, since the position of a magnet does not change unless the motor rotates, an alternating current does not flow through the motor, and current concentrates on a power element of a specific phase of an inverter that supplies a driving current to the motor. Will be. Therefore, the temperature rise of the power element in a specific phase becomes remarkable, the control for protecting the power element in a short time is activated, and the torque is limited.

On the other hand, when the vehicle starts on a flat road and climbs a steep road, the motor is already rotating when approaching the steep road. Since the motor continues to rotate as long as there is room, the current does not intensively flow through the power element of a specific phase. Therefore, it is possible to climb a steep slope.

As described above, in an electric vehicle or a hybrid vehicle using a conventional synchronous motor as a driving source, it is possible to start on a sloping road even on a steeply sloping road that can be satisfactorily climbed without stopping from a flat road. There is a problem that starting is difficult.

An object of the present invention is to improve the climbing performance of an automobile using a synchronous motor as a driving source.

[0008]

According to a first aspect of the present invention, there is provided a synchronous motor for driving a vehicle, a torque control means for calculating a torque command value of the synchronous motor, Current control means for calculating a command value of a current flowing to the synchronous motor based on the current command value, and switching a conduction pattern of a plurality of power elements to convert DC power of a battery into AC power, and converting a current corresponding to the current command value to The present invention is applied to an automobile using a synchronous motor having a power conversion means for supplying the synchronous motor as a driving source. The vehicle further includes hill start detection means for detecting hill start. When the hill start is detected, the current control means increases the current command value beyond the maximum current in the normal use area. (2) The slope start detection means of the vehicle using the synchronous motor as a driving source for driving the synchronous motor according to claim 2, wherein the synchronous motor is driven even when the torque command value is the maximum value in the normal use area and the brake is not operated. If the vehicle has stopped, it is determined that the vehicle has started on a slope. (3) The hill start detection means of the vehicle using the synchronous motor as a driving drive source according to claim 3, wherein the torque command value is a maximum value in a normal use area and the synchronous motor is in the opposite direction to the torque command value. If you are rotating in the direction of
It is determined that the vehicle starts on a slope. (4) The hill start detection means of the vehicle using the synchronous motor of claim 4 as a traveling drive source detects a stop and a rotation direction of the synchronous motor based on an energization pattern of the power element of the power conversion means. (5) An automobile using the synchronous motor as a driving source for driving according to claim 5, further comprising rotation detecting means for detecting rotation of the synchronous motor, wherein the slope start detecting means is configured to stop and operate the synchronous motor by the rotation detecting means. Detect the direction of rotation. (6) In the automobile using the synchronous motor according to claim 6 as a traveling drive source, the hill start is completed when the synchronous motor rotates in the direction of the torque command value after the hill start detection means determines that the hill starts. When it is determined that the start of the slope is completed, the current control means limits the current flowing to the synchronous motor to the maximum current in the normal use area or less. (7) The current control means of the vehicle using the synchronous motor as a driving source for driving gradually increases the current command value when the start of the slope is detected.

[0009]

According to the first aspect of the present invention, the start of a slope is detected, and when the start of a slope is detected, the current command value is increased beyond the maximum current in the normal use area. A larger torque than before can be generated by increasing the motor current beyond the maximum value of the normal use area, and it is possible to start a slope on a steeper slope than before. In addition, the vehicle can be started in a shorter time since the vehicle is started with a larger torque than before, and the time that exceeds the maximum torque in the normal use area, that is, the time that exceeds the maximum current, is reduced, and the temperature rise of the power element can be suppressed. (2) According to the invention of claim 2, when the torque command value is the maximum value in the normal use area and the synchronous motor is stopped even though the brake is not operated, it is determined that the vehicle starts on a slope. As a result, when the vehicle starts on a slope on a steep slope, the driving torque by the motor and the torque in the opposite direction due to its own weight are balanced, and the state in which the vehicle is stopped can be reliably detected. (3) According to the invention of claim 3, when the torque command value is the maximum value in the normal use area and the synchronous motor is rotating in the direction opposite to the direction of the torque command value, it is determined that the vehicle starts on a slope. Since the determination is made, the torque in the reverse direction due to its own weight is larger than the driving torque by the motor when the vehicle starts on a sloping road on a steep road, so that it is possible to reliably detect the state in which the vehicle slides down the steep road and retreats. (4) According to the invention of claim 4, since the stop and rotation direction of the synchronous motor are detected based on the energization pattern of the power element of the power conversion means, the rotational state of the synchronous motor can be detected in real time, The responsiveness of the current control, that is, the motor torque control is improved, and the motor torque can be quickly increased at the time of starting on a slope on a steep road. (5) According to the fifth aspect of the present invention, there is provided the rotation detecting means for detecting the rotation of the synchronous motor, and the rotation detecting means detects the stop and the rotation direction of the synchronous motor. The rotation direction can be reliably detected. (6) According to the invention of claim 6, after the start of the hill is determined, when the synchronous motor rotates in the direction of the torque command value, it is determined that the start of the hill has been completed. Since the current flowing to the motor is limited to the maximum current in the normal use area, the motor is driven by the current in the normal use area except when starting on a slope, and the life of the power element of the inverter can be extended as in the past. Can be planned. (7) According to the invention of claim 7, when the start of the slope is detected, the current command value is gradually increased, so that it is possible to prevent the drivability from deteriorating due to sudden start and sudden change in torque, and to smoothly drive the vehicle. Can be launched.

In the present invention, it is possible to start on a sloping road on a steeper slope than in the prior art. Such as starting from a step,
According to the present invention, even when the wheel is locked by the external environment, the possibility of starting is increased.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electric vehicle will be described. Note that the present invention is not limited to electric vehicles, but can be applied to all vehicles other than electric vehicles, such as hybrid vehicles, which use a synchronous motor as a driving source.

FIG. 1 shows the configuration of an embodiment. The electric vehicle according to one embodiment includes a power train that converts DC power of a battery 1 into AC power by an inverter 2 and supplies AC power to a three-phase synchronous motor 3 that is a driving source for driving. In this embodiment, a three-phase synchronous motor will be described as an example, but the synchronous motor is not limited to three phases. The electric vehicle also includes a torque processing controller 4 (hereinafter, simply referred to as TPC) for controlling the inverter 2 and a motor controller (hereinafter, simply referred to as MC) 5.

A torque processing controller (TPC) 4 is composed of a CPU 4a, a memory 4b, and the like. Accelerator opening information from an accelerator sensor 6 for detecting a depression amount of an accelerator pedal (hereinafter referred to as an accelerator opening), a vehicle speed, and the like. The torque command value of the synchronous motor 3 is calculated based on the vehicle speed information from the vehicle speed sensor 7 for detecting the vehicle speed.

The motor controller (MC) 5 is C
The PU 5a, the memory 5b, and the like. Based on the brake information from the foot brake switch 8 and the parking brake switch 9, the rotational position information of the synchronous motor 3 from the rotation sensor 10, the torque command value from the TPC 4, etc. A current command value to be supplied to the three-phase synchronous motor 3 from 2 is calculated. In addition, foot brake
The switch 8 is a switch that is activated when the brake pedal is depressed, and the barking brake switch 9 is a switch that is activated when the parking brake lever is operated. The rotation sensor 10 detects the rotation position of the three-phase synchronous motor 3.

Here, the limit value of the motor current at the time of starting on a slope on a steep road will be described. Generally, the output characteristics of the synchronous motor are as shown in FIG. 2, and a predetermined torque is allowed up to a predetermined rotation speed, and the torque is reduced when the rotation speed exceeds the predetermined rotation speed. Since the motor current at each rotation speed is proportional to the motor torque, the normal motor torque, that is, the usage area of the motor current has a margin with respect to the limit of the power element. There are two types of power element limitations: specification limits (hereinafter referred to as “limit current”) and life limits determined by usage such as the guaranteed life. It is often used at a value about 20 to 40% lower than the limit current. Further, when the motor rotational speed changes suddenly as in the case of a slip, it is necessary to consider that the motor current temporarily jumps due to a response delay of the motor control.

Therefore, the normal use area of the motor torque (motor current) has a sufficient margin to reach the power element limit as shown in FIG. 2, and is rarely used as in the case of starting on a slope on a steep road. Under such running conditions, the motor torque (motor current) can be increased beyond the normal use area.

Therefore, in this embodiment, at any point larger than the maximum torque (maximum current) and smaller than the power element limit torque (limit current) in the normal use area shown in FIG. A limit value of the torque (motor current) is set, and when the vehicle starts on a slope on a steep road, the motor torque, that is, the motor current is allowed to increase to the limit value. Specifically, when the vehicle starts on a sloping road on a steep slope, the motor 3 is rotated and the motor current command value is increased beyond the maximum current with the above-mentioned limit value as an upper limit until the starting of the sloping road is completed. After the start of the slope is completed, the motor current command value is returned to the maximum current or less in the normal use area. The above-mentioned limit value of the motor current command value applied when starting on a steep slope is set based on the specifications and ratings of the power element and the motor, the performance of the vehicle itself, and the like.

Thus, when the vehicle starts on a slope on a steep slope, a larger torque than the conventional motor can be generated by an increase in the motor current exceeding the maximum value in the normal use area. Slope start on a sloping road becomes possible. In addition, the vehicle can be started in a shorter time since the vehicle is started with a larger torque than before, and the time that exceeds the maximum torque in the normal use area, that is, the time that exceeds the maximum current, is reduced, and the temperature rise of the power element can be suppressed.

When the motor torque command value is equal to or less than the maximum torque in the normal use area shown in FIG. 2, the torque of the three-phase synchronous motor 3 is equal to or less than the maximum torque in the normal use area, that is, equal to or less than the maximum current. The output current of the inverter 2 is controlled so that Such control is referred to as normal control in this specification.

FIGS. 3 and 4 are flowcharts showing motor current control according to one embodiment. MC5 CPU5a
Executes the motor current control program upon input of information from the TPC 4 that the accelerator opening is in the fully opened state. In step 1, a torque command value is input from the TPC 4, and it is determined whether or not the torque command value is a preset maximum value in the normal use area. If the torque command value is not the maximum value in the normal use area, the process proceeds to step 2 to perform normal control, and it is checked whether the steep start flag indicating that the vehicle is starting on a slope on a steep road is set (= 1). . If the steep start flag has been set, the routine proceeds to step 10, where the flag is reset (= 0). On the other hand, when the steep start flag is not set, the routine proceeds to step 11, where normal control is performed.

On the other hand, if the torque command value has reached the maximum value in the normal use area, it is checked in step 3 whether the motor 3 has stopped.

Normally, the three-phase inverter 2 has a DC link P
, U, V, and W phases on the DC link N side, and U, V, and W phases on the DC link N side.
When applying an AC current to the
Make it conductive. Therefore, when the three-phase synchronous motor 3 is rotating, the energization pattern of the power elements of the inverter 2 always changes, and the energization order of the power elements differs according to the rotation direction of the motor 3. In other words, when the energization pattern of the power element of the inverter 2 is changing, the motor 3 is rotating in a direction according to the energization order of the power element. Conversely, when the energization pattern is not changing, the motor 3 is rotating. 3 is stopped.

In this embodiment, the rotation or stop of the motor 3 is determined based on the energization pattern of the power element of the inverter 2, and if the energization pattern has not changed, it is determined that the motor 3 has stopped. When the energization pattern is changing, the rotation direction of the motor 3 is detected based on the energization order of the power elements of each phase.

The rotation or stop of the motor 3 can be detected based on the rotation position signal from the rotation sensor 10. However, since the rotation position signal from the rotation sensor 10 has a delay, the current control is correspondingly delayed. That is, the response of the motor torque control is reduced. In this embodiment, since the rotation, stop and rotation direction of the motor 3 are detected based on a change in the energization pattern of the power element of the inverter 2, the rotation state of the motor 3 can be detected in real time, and the current control, that is, the motor torque The responsiveness of the control is improved, and the motor torque can be quickly increased when starting on a slope on a steep road.

First, the case where the motor 3 is stopped will be described. When the motor 3 is stopped, the process proceeds to step 4 to check whether the foot brake or the parking brake is operated. When the brake is operated and the motor 3 is stopped, it is determined that the vehicle has not started on a hill, and the routine proceeds to step 5 to perform normal control.
Proceed to. Then, if the steep start flag is set, it is reset in step 10 and then the above-described normal control is performed in step 11.

The torque command value is the maximum value in the normal use area,
If the motor 3 is stopped even though the brake is not operated, it is determined that the vehicle is starting on a slope on a steep road, and it is checked in step 6 whether the steep start flag is set. If the steep start flag is not set, it is set in step 7. If it is recognized that the vehicle starts on a steep slope, the motor current command value is increased in step 8 beyond the maximum current in the normal use area with the above-described limit value as the upper limit.

Here, the method of increasing the current of the motor 3 may be a method of linearly increasing so as to reach the above-mentioned limit value in a predetermined time, for example, 5 seconds as shown in FIG. As shown in FIG.

Next, in step 9, the motor 3 after the motor current is increased beyond the maximum value in the normal region.
Check the rotation status of. If the motor 3 does not rotate even when the motor current reaches the limit value, it is determined that the vehicle is on a steep road that exceeds the limit of the ascending performance of the vehicle, and step 1 is performed.
After proceeding to 0 and resetting the steep start flag, the routine proceeds to the above-described normal control in step 11. On the other hand, if the motor 3 rotates after the motor current reaches the limit value or before the motor current reaches the limit value, the process returns to step 1 and the above-described processing is repeated. In other words, when the vehicle starts on a slope on a steep road, the processing of steps 1 to 9 is repeated until the motor 3 rotates in the direction of the torque command value. I do. FIG. 9 shows a change in motor current when the vehicle starts on a slope on a steep road.

On the other hand, if it is determined in step 3 that the motor 3 is not stopped, the process proceeds to step 21. That is, when the torque command value is the maximum value of the normal use area and the motor 3
Is rotating, it is checked in step 21 whether the motor 3 is rotating in the direction of the torque command value. If the motor 3 is rotating in the direction of the torque command value, it is determined that the vehicle has started after the start of the slope on the steep road, and the process proceeds to step 22 to check whether the steep start flag is set. I do. If the steep start flag is set, the process is reset in step 10 and then the process proceeds to the normal control in step 11.

The torque command value is the maximum value in the normal use area,
If the motor 3 is rotating, but the motor 3 is not rotating in the direction of the torque command value, the process proceeds to step 23.
When the torque command value is the maximum value in the normal use area and the motor 3 is rotating in the direction opposite to the direction of the torque command value, the vehicle slides down a steep road when starting up a hill, that is, retreats. It is determined in step 23 whether or not the steep start flag is set in step 23, and if not, it is set in step 24. Thereafter, in step 25, the motor current command value is increased beyond the maximum current in the normal use area with the above-mentioned limit value as the upper limit. The motor current is increased by the method shown in FIGS.

Next, in step 26, the rotation state of the motor 3 after the motor current is increased beyond the maximum value in the normal use area is confirmed. When the motor 3 does not rotate in the direction of the torque command value even when the motor current reaches the above limit value, that is, when the vehicle slides down a steep road and the motor 3 rotates in the direction opposite to the torque command value. Then, it is determined that the road is a steep road exceeding the limit of the vehicle's uphill performance, and the process proceeds to step 10 to reset the steep start flag, and then proceeds to the normal control described above in step 11. On the other hand, if the motor 3 rotates in the direction of the torque command value before the motor current reaches the limit value, the process returns to step 1 and the above-described processing is repeated. That is, when the vehicle starts on a sloping road when the vehicle is sliding down on a steep road, the processing of steps 1, 3, 21, and 23 to 26 is repeated until the motor 3 rotates in the direction of the torque command value. When 3 rotates in the direction of the torque command value, the control shifts to the normal control. At this time, the motor current changes as shown in FIG.

In the configuration of the above embodiment, the three-phase synchronous motor 3 is a synchronous motor, the torque processing controller 4 is a torque control means, the motor controller 5 is a current control means and a hill start detection means, and the inverter 2 Is the power conversion means, the rotation sensor 1
0 constitutes the rotation detecting means.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment.

FIG. 2 is a diagram illustrating output characteristics of a synchronous motor.

FIG. 3 is a flowchart illustrating a motor current control program when the accelerator is fully opened according to the embodiment;

FIG. 4 is a flowchart following FIG. 3 showing a motor current control program when the accelerator is fully opened according to the embodiment;

FIG. 5 is a diagram showing a method of increasing a motor current.

FIG. 6 is a diagram showing a method of increasing a motor current.

FIG. 7 is a diagram showing a method of increasing a motor current.

FIG. 8 is a diagram showing a method of increasing a motor current.

FIG. 9 is a diagram showing a change in motor current when a hill starts on a steep road.

[Explanation of symbols]

 Reference Signs List 1 battery 2 inverter 3 three-phase synchronous motor 4 torque processing controller (TPC) 4a CPU 4b memory 5 motor controller (MC) 5a CPU 5b memory 6 accelerator sensor 7 vehicle speed sensor 8 foot brake switch 9 parking brake switch 10 rotation sensor

Claims (7)

[Claims] 1. A synchronous motor for driving and driving an automobile, a torque control means for calculating a torque command value of the synchronous motor, and a command value of a current flowing to the synchronous motor based on the torque command value. A synchronous motor comprising: a current control unit; and a power conversion unit that converts a DC power of a battery into an AC power by switching an energization pattern of a plurality of power elements and supplies a current corresponding to the current command value to the synchronous motor. A vehicle having a traveling drive source, comprising a slope start detection means for detecting a slope start, wherein the current control means increases the current command value beyond the maximum current in a normal use area when the slope start is detected. An automobile using a synchronous motor as a driving source. 2. The vehicle using a synchronous motor as a driving source according to claim 1, wherein the slope start detecting means determines that the torque command value is a maximum value in a normal use area and the brake is not operated. (2) When the synchronous motor is stopped, it is determined that the vehicle starts on a slope, and the vehicle is driven by the synchronous motor. 3. The vehicle according to claim 1, wherein said synchronous motor is a driving source of driving, and said slope start detecting means is configured such that said torque command value is a maximum value in a normal use area and said synchronous motor is said torque command value. An automobile that uses a synchronous motor as a driving source for driving when the vehicle is rotating in a direction opposite to the direction of the value, and determines that the vehicle starts on a slope. 4. An automobile using a synchronous motor as a driving source according to claim 2 or 3, wherein said slope start detecting means is configured to detect said synchronous motor based on an energization pattern of said power element of said power converting means. An automobile using a synchronous motor as a traveling drive source, characterized by detecting a stop and rotation direction of the vehicle. 5. An automobile using a synchronous motor as a driving source according to claim 2 or 3, further comprising: rotation detecting means for detecting rotation of the synchronous motor; An automobile using a synchronous motor as a drive source for driving the synchronous motor, wherein a stop and a rotation direction of the synchronous motor are detected by means. 6. A vehicle using a synchronous motor according to claim 2 as a driving source for driving the vehicle, wherein the hill start detecting means determines that the hill starts and then starts the torque command. If it is determined that the start of the slope is completed when the vehicle starts rotating in the direction of the value, the current control means determines that the start of the slope has been completed.
An automobile using a synchronous motor as a drive source for driving the synchronous motor, wherein a current flowing through the synchronous motor is limited to a maximum current or less in a normal use area. 7. An automobile using a synchronous motor as a driving source according to any one of claims 1 to 6, wherein said current control means gradually increases said current command value when a start on a slope is detected. An automobile using a synchronous motor as a driving source for driving.