JP2005117718A - Method and device for controlling torque of vehicle driven by motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce torque shock during transition from rotational speed control to torque control. <P>SOLUTION: The device comprises a vehicle speed sensor 7, a motor rotational speed sensor 2, a vehicle controller 5 for calculating a torque command value Te to a motor 1 based on the open degree of an accelerator, etc. of an accelerator pedal 6, and a motor controller 4 for instructing pulse width of an AC current generated by an inverter 3 which drives the motor 1. An output limit circuit in the vehicle controller 5 applies output limit on the torque value outputted from a torque map in a torque control mode based on the instruction from CPU. The torque command value Te just after switching from a rotational speed control mode to the torque control mode is made identical with a torque command value Te in previous rotational speed control mode, for sequentially switching the torque command value Te, and the torque value thereafter is released for output limit at a constant ratio. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a torque control device and a torque control method for a vehicle driven by an electric motor.

  The conventional electric assist device using an electric motor has been controlled so as to maintain the speed set by the driver even when the road surface condition changes, such as when the vehicle climbs over a step.

JP 2002-78752 A

  When this conventional technology is applied to a motor-driven vehicle (electric vehicle), as long as the driver steps on the accelerator pedal at a constant speed, the vehicle travels at a constant speed regardless of changes in road conditions such as the slope (number of revolutions). When applied to an electric vehicle that realizes a driving feeling similar to that of a gasoline car (torque control), the driving feeling is different from that of a gasoline car and is very uncomfortable.

  On the other hand, it is desirable that the vehicle travels at a constant speed when overcoming a step, but if the vehicle shifts from the rotational speed control to the torque control after overcoming the step, a torque shock may occur, giving the passenger an uncomfortable feeling.

  The present invention has been made to solve the above-described problem, and an object thereof is to provide a torque control device and a torque control method in an electric motor-driven vehicle that reduce torque shock when shifting from rotational speed control to torque control. It is said.

  In order to achieve the above object, in the present invention, the torque of the electric motor is continuously changed from the torque set during the rotational speed control to the torque set during the torque control.

  According to the present invention, when the electric motor is shifted from the rotation speed control to the torque control, the torque shock is reduced by limiting the output to the torque command value instructed by the torque control.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof is omitted.

  An embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a configuration diagram of an embodiment of the present invention. The configuration of the embodiment of the present invention will be described with reference to FIG. The embodiment of the present invention is applied to an electric vehicle driven by the electric motor 1, and includes a vehicle speed detector 7 that detects the speed of the vehicle, an electric motor rotational speed detector 2 that detects the rotational speed of the electric motor 1, and driving A vehicle controller 5 (motor control) that calculates a torque command value Te for commanding a torque required for the motor 1 from an accelerator opening (accelerator pedal operation amount), a motor speed, a vehicle speed, etc. And an AC current (U, V, W) for driving the motor generated by the inverter 3 in order to cause the motor 1 to generate a torque having the torque command value Te based on the torque command value Te from the vehicle controller 5. The pulse width (PWM: Pulse Wide Modulation) and the motor controller 4 for generating the PWM signal, and the motor controller 4 In order to cause the electric motor 1 to generate a torque command value Te based on the PWM signal, the inverter 3 is configured to supply an alternating current (U, V, W) to the electric motor 1.

  FIG. 2 is a diagram showing the internal configuration of the vehicle controller 5, and the configuration and operation of the vehicle controller 5 will be described with reference to FIG.

  The accelerator opening according to the operation amount of the accelerator 6 is converted into a digital signal by the A / D converter 21, and the accelerator opening (hereinafter, without distinguishing between the accelerator opening of the analog value and the accelerator opening of the digital value). Is supplied to the torque map 22 or the rotational speed map 23.

  During normal torque control (torque control mode), the torque map 22 is used to determine the torque value to be output to the motor controller 4 based on the motor speed and the accelerator opening, and output to the output limiting circuit 25. That is, the second torque value is based on the operation amount of the accelerator pedal operated by the driver.

  The output limiting circuit 25 limits the torque value output from the torque map 22 based on the command of the CPU 24, and sets the torque command value Te immediately after switching to the torque control mode from the rotation speed control (rotation speed control mode). In the same manner as the torque command value Te (first torque value) in the immediately preceding rotation speed control mode, the torque command value Te is continuously switched, and the subsequent torque value is released at a constant ratio, and this output is released. The limited torque value (second torque value) is output to the motor controller 4 as the torque command value Te. That is, when switching from the first torque value to the second torque value, the second torque value is continuously changed by matching the first torque value, and the subsequent second torque is also controlled by the amount of operation of the accelerator pedal. The torque value based on is output at a constant ratio.

  On the other hand, in the rotational speed control mode, the rotational speed MAP 23 is a proportional / integral controller (PI controller) that determines the rotational speed required for the electric motor 1 from the accelerator opening (the vehicle speed is kept constant by keeping the rotational speed constant). 26. The PI controller 26 performs a proportional / integral calculation so that the required rotational speed of the motor 1 output from the rotational speed MAP 23 matches the rotational speed of the motor detected by the motor rotational speed detector 2. A torque value required for the motor controller 4 is output so that the rotational speed matches the actual motor rotational speed. That is, a constant vehicle speed is maintained by keeping the rotation speed constant. The output of the PI controller 26 is output as a torque command value Te to the motor controller 4 through the filter 27 so as not to give the driver a sense of incongruity due to a sudden change in the torque value of the output of the PI controller 26.

  The CPU 24 switches between the torque control mode and the rotational speed control mode according to the vehicle speed, the accelerator opening degree, and the like, and applies an output limit to the output torque value from the torque map 22 after switching from the rotational speed control mode to the torque control mode. An instruction is sent to the output limiting circuit 25.

  Next, the operation to switch from the normal torque control mode to the rotation speed control mode such as when overcoming the vehicle, such as when the vehicle goes over a step, and the operation to switch from the rotation speed control mode to the normal torque control mode, i.e., this embodiment 2, FIG. 4, accelerator opening-motor rotation speed (set vehicle speed) setting value, FIG. 5 flowchart, FIG. 6 mode switching time chart (step difference) This will be described with reference to a case where acceleration is performed after overriding) and a time chart at the time of mode switching in FIG.

  First, an operation for switching from the normal torque control mode to the rotation speed control mode when overcoming a step will be described with reference to FIG.

First, the vehicle speed _Vve is detected (step 301) in order to detect that the vehicle is not advanced (torque control mode a in FIG. 6) when the tire is caught on a step or the like and the accelerator is stepped on. Next, the vehicle speed _Vve is, for example, less than 2 km / h (step 302), and the accelerator opening A _ac (step 303) at this time exceeds 10% and is maintained below 40% (step 304). when the value of _{T 1} counter for counting the the times _{T 1} is measured that exceeded 0.4 seconds (step 305 and 306), controlled by CPU24 to switch to speed control mode for overcoming step. A lamp is lit to notify the driver that the mode has been switched to the rotation speed control mode.

  On the other hand, when the vehicle speed is 2 km / h or more (step 302) or the accelerator opening is 10% or less (step 304), the T1 counter is cleared (step 307) and the initial state is restored.

  After switching to the rotation speed control mode, the vehicle is controlled according to the rotation speed map 23 based on the accelerator opening-motor rotation speed (vehicle speed) set value shown in FIG. Since the vehicle controller 5 sets the rotation speed (vehicle speed) based on the accelerator opening according to the rotation speed map 23, the PI controller 26 increases the rotation of the accelerator up to that point, so that the electric motor 1 has the rotation speed map 23. 6 is detected (the vehicle does not advance), and a large torque is generated so as to reach the rotational speed based on the accelerator opening (to reach a constant vehicle speed) (rotational speed control in FIG. 6). Mode) and the rotational speed (vehicle speed) are brought close to the rotational speed (vehicle speed) based on the accelerator opening. At this time, since a sudden torque fluctuation occurs, the output torque value of the PI controller is passed through the filter 27. As a result, the rapid fluctuation of the torque value is suppressed and the torque command value Te is output to the motor controller 4.

  Since the rotational speed (vehicle speed) approaches or coincides with the rotational speed output from the rotational speed map 23 due to the large torque designation value Te, the vehicle speed is constant after the vehicle has climbed over the step, so that the driver depresses the accelerator. Maintain the amount or decrease the amount of depression.

  Next, the case of returning from the rotation speed control mode to the normal torque control mode will be described based on the flowchart of FIG.

  Rotation speed control mode (step 307) sets the rotation speed (target speed) based on the accelerator opening (step 502), and the accelerator opening is 0% when the vehicle gets over the step and the driver releases the accelerator. In the case of (Step 503), the torque control mode is unconditionally returned (Step 503). That is, when the accelerator opening becomes 0%, the first torque value is switched to the second torque value.

When the driver is still operating the accelerator (step 503), the CPU 24 monitoring the torque command value Te determines whether the torque command value Te is, for example, 5 Nm or less (a predetermined torque specified value or less) (step 504). ), and the torque command value Te to time continues below 5 Nm (up the count of the T ₂ counter for measuring a predetermined duration maintained) (step 505). On the other hand, when the torque command value Te exceeds 5 Nm, Clear _{T 2} counter (step 512) returns initially.

  If the torque command value Te continues to be 5 Nm or less and the driver continues operating the accelerator (step 506) for more than 1 second (maintains beyond the predetermined duration) (step 507), the rotational speed The control mode is shifted to the torque control mode with output limit (step 508). That is, when the state where the first torque value is equal to or less than the predetermined torque value is maintained for a predetermined duration, the first torque value is switched to the second torque value.

  This torque control mode with output limitation is for the purpose of eliminating torque shock when switching from the rotational speed control mode to the torque control mode, and the torque command value Te commanded in the rotational speed control mode immediately before switching to the torque control mode. In order to match the torque command value Te output when the torque control mode is switched to, the torque value corresponding to the accelerator opening is output from the torque map 22 in the torque control mode, but immediately before the CPU 24 switches to the torque control mode. The output limit circuit 25 is instructed to limit the output based on the torque command value Te commanded in the engine speed control mode and the accelerator opening, and the engine speed immediately before the torque value output from the torque map 22 is switched to the torque control mode. The torque command value Te commanded in the control mode is made coincident. Thereafter, the CPU 24 controls the output restriction change rate so as to change at a constant change rate as shown in the output restriction release of FIG. 6 to release the output restriction (torque control mode b in FIG. 6).

  Even when the speed control mode is switched from the rotation speed control mode to the torque control mode mode after stepping over the level difference, there is no torque change. Can do.

  In addition, when the stop is scheduled after the step change over to the torque control mode after overcoming the step, as shown in the torque control mode c in FIG. The degree becomes 0%, and the torque control mode with output restriction is immediately shifted to the torque control mode, so that the output restriction is eliminated. Note that, in the torque control mode c, the driver has released his or her foot from the accelerator in a plan to stop, but has not stepped on the brake, so the vehicle is moving by inertia and then the accelerator is depressed and accelerated.

  As described above, by switching from the torque control mode to the rotation speed control mode, the level difference can be overcome smoothly. When switching from the rotation speed control mode to the torque control mode, the torque immediately after the switching is made the same. After that, by releasing the restriction on the output torque at a constant rate of change, switching can be performed without causing discomfort to the driver or the occupant.

The block diagram of the electric motor drive vehicle of embodiment of this invention. The internal block diagram of a vehicle control controller. The flowchart in the case of switching from torque control mode to rotation speed control mode. Accelerator opening-motor speed (set vehicle speed) set value. The flowchart in the case of switching from a rotation speed control mode to a torque control mode. Time chart when switching modes (when accelerating after overcoming a step). Time chart at the time of mode switching (when stopping is planned after overcoming a step).

Explanation of symbols

1 Electric Motor 5 Vehicle Controller 6 Accelerator Pedal 22 Torque MAP
23 MAP
24 CPU
25 Output limit circuit

Claims (8)

In the torque control device in an electric motor drive vehicle provided with an electric motor for driving the vehicle,
Electric motor control means for causing the electric motor to output one of a first torque value set for traveling at a constant vehicle speed and a second torque value set in response to the operation of the driver; Equipped,
The electric motor control means continuously changes the output of the electric motor from the first torque value to the second torque value when switching from the first torque value to the second torque value. A torque control device for an electric motor-driven vehicle.   2. The electric motor according to claim 1, wherein when the output of the electric motor is switched from the first torque value to the second torque value, the second torque value is increased or decreased at a constant rate of change. Torque control device for driving vehicle.   The torque control apparatus for an electric motor-driven vehicle according to claim 1, wherein the second torque value is based on an operation amount of an accelerator pedal operated by a driver.   The torque control apparatus for an electric motor-driven vehicle according to claim 3, wherein the second torque value is increased or decreased at a constant change rate with respect to a torque value based on an operation amount of the accelerator pedal.   The torque control apparatus for an electric motor-driven vehicle according to claim 1, wherein the constant vehicle speed based on the first torque value is maintained by setting the rotation speed of the electric motor to a constant rotation speed.   2. The torque control device for an electric motor-driven vehicle according to claim 1, wherein when the accelerator opening becomes 0%, the first torque value is switched to the second torque value. 3.   The first torque value is switched from the first torque value to the second torque value when a state where the first torque value is equal to or less than a predetermined torque value is maintained for a predetermined duration. The torque control apparatus in the electric motor drive vehicle of 1. In a torque control method in an electric motor drive vehicle including an electric motor for driving the vehicle,
Either one of a first torque value for running at a constant vehicle speed and a second torque value corresponding to the operation of the driver is output to the electric motor;
When the output of the electric motor is switched from the first torque value to the second torque value, the output is continuously changed from the first torque value to the second torque value. A torque control method in an electric motor driven vehicle.

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