JP2021108511A - Control device - Google Patents

Abstract

To accurately calculate acceleration required for speed control in decelerating a vehicle.SOLUTION: In an acceleration calculation unit 5 of an ECU 3, a mechanical resonance frequency component is reduced from an acceleration signal from an acceleration calculation unit 31 by a notch filter 33. Furthermore, noise from various sensors is reduced by a low pass filter 35, and accurate acceleration data is acquired. Thereby, in decelerating a vehicle 1 when automatic speed control is executed, a noise signal that interferes with vehicle traveling control is reduced from acceleration data obtained by subjecting speed data to time differential by using both the notch filter 33 and the low pass filter 35 so that appropriate target acceleration can be calculated.SELECTED DRAWING: Figure 2

Description

The present invention relates to a control device for a vehicle such as an electric vehicle.

In vehicles such as electric vehicles and hybrid vehicles, detection signals from various sensors and signals from in-vehicle devices are input to the ECU (Electronic Control Unit) to determine the running state of the vehicle, the driving operation state by the driver, and the like. ing.

Patent Document 1 considers a problem that a waveform obtained by time-differentiating the vehicle speed detected by the vehicle speed sensor becomes oscillating, and if the waveform is applied as it is to vehicle control as the acceleration of the vehicle, a control problem occurs. Therefore, a technique is disclosed in which a low-pass filter process is applied to the time derivative value of the vehicle speed to reduce high-frequency noise, and a gradient limiting process is applied to the high-frequency noise reduction value to reduce steady vibration.

Japanese Unexamined Patent Publication No. 2016-200564

The noise generated in the vehicle includes not only the noise from the various sensors described above but also the noise due to the mechanical structure of the vehicle (noise component due to the mechanical resonance frequency). The vibration component of the noise due to such mechanical resonance has a problem that it cannot be removed by the low-pass filter processing because the frequency band is different from the noise caused by the sensor.

Further, since the acceleration data obtained from the instantaneous value of the velocity includes mechanical resonance noise, if the acceleration data as it is is used, the control unit in the next stage may cause erroneous recognition of the acceleration.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a control device capable of accurately calculating acceleration in speed control during deceleration of a vehicle.

The following configuration is provided as a means for achieving the above object and solving the above-mentioned problem. That is, the first exemplary invention of the present application is a control device that controls the running of a vehicle according to a target speed, and has a vehicle speed detection unit that detects the speed of the vehicle and a vehicle speed detected by the vehicle speed detection unit. An acceleration calculation unit that calculates acceleration based on the acceleration, a notch filter that removes a predetermined frequency signal component from the output signal of the acceleration calculation unit, and a low-pass filter that reduces signal components of a certain frequency or higher from the output signal of the acceleration calculation unit. And a means for setting a target acceleration based on the acceleration after filtering by the notch filter and the low-pass filter, and calculating the target speed at the time of deceleration of the vehicle by using the target acceleration. It is characterized by.

The second exemplary invention of the present application is an inverter device for driving an electric motor, and the torque of the electric motor so as to follow the target speed generated by the control device according to the first exemplary invention. It is characterized by including means for generating a command signal and means for driving and controlling the electric motor by the torque command signal.

An exemplary third invention of the present application is an automobile, characterized in that it includes an inverter device according to the second exemplary invention.

An exemplary fourth invention of the present application is a control method for controlling the running of a vehicle according to a target speed, in which an acceleration is calculated based on a step of detecting the speed of the vehicle and a vehicle speed detected in the detection step. A step of removing a predetermined frequency component from the acceleration signal calculated in the calculation step by a notch filter, and a low-pass filter from the acceleration signal after filtering in the first filter processing step. A second filter processing step of reducing signal components above a certain frequency, a step of setting a target acceleration based on the acceleration after filtering by the second filter processing step, and a target acceleration determined in the setting step. It is characterized by including a step of calculating the target speed at the time of deceleration of the vehicle by using.

According to the present invention, the control device performs speed control based on an acceleration signal from which both the mechanical resonance frequency component and the sensor noise component caused by the mechanical structure of the vehicle are removed, thereby decelerating and stopping the vehicle. A good ride can be obtained at times.

FIG. 1 is a block diagram showing an overall configuration of a vehicle equipped with an electronic control device for a vehicle according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of an acceleration calculation unit of the ECU. FIG. 3 is an example of the frequency characteristics of the notch filter and the low-pass filter. FIG. 4 is a flowchart showing the vehicle stop processing in the control device according to the embodiment in chronological order. FIG. 5 is a block diagram showing another configuration example of the acceleration calculation unit of the ECU.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an overall configuration of a vehicle equipped with an electronic control device for a vehicle (hereinafter, also simply referred to as a control device) according to an embodiment of the present invention.

In FIG. 1, the vehicle 1 is derived from an electronic control unit (ECU) 3 which is a motor control device, a vehicle control unit (VCU: Vehicle Control Unit) 2 which is a higher control device (upper controller) of the ECU 3, and an ECU 3. It is provided with a motor control unit (MCU) 9 that drives the electric motor 15 according to the control signal of the above, a transmission 11 that is connected to the electric motor 15 and transmits the rotational driving force to the wheels 13a and 13b.

The vehicle 1 is, for example, an electric vehicle (EV) and includes a battery (not shown) that supplies drive power to the electric motor 15. Further, the vehicle 1 is a vehicle capable of automatically speed-controlling acceleration, deceleration, and stopping by one pedal operation.

The automatic speed control here means, for example, that one pedal has the functions of both an accelerator pedal and a brake pedal, and when the pedal stroke by the driver's pedal operation is depressed from a predetermined position, the vehicle is operated. It is a control to decelerate the vehicle when accelerating and stepping back from a predetermined position.

The ECU 3 is composed of, for example, a microcomputer that receives various signals and controls the entire ECU 3. The ECU 3 transmits an output signal corresponding to the acceleration request, the deceleration request, and the stop request to the vehicle 1 to the MCU 9, and drives and controls the electric motor 15.

The ECU 3 includes a read-only memory (ROM) in which various control programs and the like are stored in advance, and a storage unit (not shown) in which control results and calculation results are stored.

The MCU 9 includes an inverter circuit 10 that supplies a drive current to the electric motor 15. The inverter circuit 10 is composed of a plurality of semiconductor switching elements (FETs), and power for driving a motor is supplied from an external battery.

The switching element (FET) is also called a power element, and for example, a switching element such as a MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor) is used.

The electric motor 15 is, for example, a three-phase brushless DC motor, and the semiconductor switching elements constituting the three-phase (U-phase, V-phase, W-phase) inverter circuit 10 correspond to each phase of the electric motor 15. The electric motor 15 performs a power running operation as a rotationally driven electric motor and a regenerative operation in which the rotor receives rotational energy from a drive wheel or the like and operates as a generator.

The speed calculation unit 8 obtains the rotation angle of the electric motor 15 based on the signal from the position detector 17 arranged in the vicinity of the electric motor 15, and calculates the motor rotation speed based on the rotation angle. When a resolver is used as the position detector 17, for example, the accuracy of detecting the rotational position and the durability under high temperature can be improved as compared with a Hall element or the like. On the other hand, when the Hall element 17 is used, the configuration can be made cheaper than that of a resolver, an encoder, or the like.

When the accelerator pedal 21 is operated by the driver in the vehicle 1, the amount of operation (accelerator opening degree) is detected by an accelerator opening degree sensor (not shown). The VCU 2 generates a signal for controlling acceleration, deceleration, etc. of the vehicle 1 based on the accelerator opening information from the accelerator opening sensor.

When the brake pedal 23 is operated during automatic speed control, the VCU 2 transmits a signal according to the amount of brake operation from a brake stroke sensor (not shown) to the brake control unit 25. The brake control unit 25 controls the brake mechanism 27 including the brake pads, the hydraulic mechanism, and the like to stop the vehicle 1.

The brake control may include a regenerative brake control that generates a braking force due to the regenerative amount of the electric motor 15.

The VCU 2 calculates a target torque according to the actual drive torque of the electric motor 15 when the vehicle 1 is running, and controls the torque of the electric motor 15 so as to follow the torque command value (torque control). The speed control (speed control) for controlling (holding) the actual rotation speed of the electric motor 15 to be the target rotation speed is switched.

At the time of torque control, the VCU 2 calculates a torque command value for realizing the required driving force (acceleration request, deceleration request) for the electric motor 15 based on, for example, the depression amount of the accelerator pedal 21 and the vehicle speed, and commands the torque command value. It is input to the ECU 3 as the torque Trq *. The ECU 3 generates a motor drive signal (PWM (Pulse Width Modulation) signal) according to the command torque Trq *.

The motor drive signal generated by the ECU 3 is input to the inverter circuit 10 in the MCU 9 which functions as an FET drive circuit (motor drive circuit). The semiconductor switching elements constituting the inverter circuit 10 are ON / OFF controlled by a motor drive signal, and a predetermined drive current is supplied from the inverter circuit 10 to the electric motor 15 to drive and control the electric motor 15.

On the other hand, at the time of speed control, the acceleration calculation unit 5 of the ECU 3 calculates the target acceleration from the speed data input from the VCU 2 as described later. The calculated target acceleration is input to the target speed setting unit 7. The MCU 9 controls the rotation speed of the electric motor 15 based on the target speed from the target speed setting unit 7.

FIG. 2 is a block diagram showing a configuration of an acceleration calculation unit of the ECU. In FIG. 2, the acceleration calculation unit 31 obtains acceleration data from the speed data obtained by differentiating the angle information during the speed control described above.

The output signal from the acceleration calculation unit 31 is input to the notch filter 33, which is a band removal filter, and reduces a predetermined frequency signal component from the acceleration signal. Specifically, the notch filter 33 removes or reduces unnecessary mechanical resonance frequency components generated due to the mechanical structure of the vehicle 1 or the like.

There may be a plurality of mechanical resonance frequencies due to the structure of the vehicle 1, fluctuations in the load weight on the vehicle 1, etc., but by determining the notch frequency of the notch filter 33 according to the mechanical resonance frequency of the vehicle 1, Unnecessary mechanical resonance frequency components included in acceleration data can be efficiently reduced pinpointly.

The output signal from the notch filter 33 is further input to the low-pass filter 35. The low-pass filter 35 reduces signal components (noise from various sensors) having a certain frequency or higher than the output signal from the notch filter 33.

FIG. 3 shows an example of the frequency characteristics of the notch filter 33 and the low-pass filter 35. The notch filter 33 is, for example, a digital filter, and has an attenuation characteristic in which the above-mentioned mechanical resonance frequency (for example, a frequency near 10 Hz) is set to a notch frequency (ω _0).

As shown by the solid line in FIG. 3, the notch filter 33 reduces the notch frequency component and the frequency component in the vicinity thereof from the input signal and outputs the notch frequency component by minimizing the amplitude gain at the _{notch frequency ω 0.}

The notch frequency ω ₀ is a center frequency that attenuates the input signal, and the frequency characteristic of the notch filter 33 can be represented by a Q value, which is a parameter indicating the notch width, as shown by the following equation (1). ..

Q = ω ₀ / (ω _{2 -ω 1} )… (1)

Ω ₂ -ω ₁ of the formula (1) is referred to as a full width at half maximum. As shown in FIG. 3, the _{frequency ω 1} that gives the half width _{is lower than ω 0} and the amplitude is half of the resonance peak (the frequency at which the amplitude gain of the blocking band is -3 dB of the gain of the pass band). Is. _{Similarly, the frequency ω 2} that gives the full width at half maximum is a frequency whose frequency is higher than ω _{0 and} whose amplitude is half the value of the resonance peak (the frequency at which the amplitude gain of the blocking band is -3 dB of the gain of the pass band).

In the notch filter 33, the larger the Q value, the narrower the notch width. The Q value of the notch filter 33 having the characteristics shown in FIG. 3 is, for example, 0.7 to 0.8.

The low-pass filter 35 is, for example, a digital filter, and has a characteristic of reducing noise signal components having a certain frequency or higher generated by the above-mentioned various sensors from the signal output from the notch filter 33. Here, as shown by the alternate long and short dash line in FIG. 3, the cutoff frequency ωc of the low-pass filter 35 is set higher than _{the notch frequency ω 0 of the notch filter 33.} The cutoff frequency ωc is, for example, a frequency of several hundred Hz, more specifically, a frequency near 300 Hz.

The cutoff frequency ωc of the low-pass filter 35 is determined according to the frequency of noise generated by various sensors mounted on the vehicle 1. By using the low-pass filter 35 as a first-order low-pass filter, for example, a filter performance (attenuation rate) of −20 dB / dec can be realized. The order of the low-pass filter 35 is not limited to the primary order.

Furthermore, by using a low-pass filter, it is possible to suppress the phase delay in the filter processing, suppress the processing (calculation) load, and reduce unnecessary sensor noise included in the acceleration data.

If both the mechanical resonance frequency component and the noise signal component caused by the sensor, which have different frequency bands as described above, are reduced only by the low-pass filter, the necessary frequency component is also reduced. Therefore, in the acceleration calculation unit 5, by using the notch filter 33 and the low-pass filter 35 having different frequency characteristics in combination, unnecessary noise signal components included in the acceleration data output from the acceleration calculation unit 31 are reduced, and a necessary signal is obtained. A more accurate target acceleration can be calculated from the components.

Next, the vehicle stop processing in the control device according to the present embodiment will be described. FIG. 4 is a flowchart showing the vehicle stop processing in the control device according to the present embodiment in chronological order.

The electronic control unit (ECU) 3 controls the driving force based on the stroke amount of the accelerator pedal 21 to accelerate the vehicle 1 and causes the accelerator pedal 21 to be depressed (for example, the amount of return of the accelerator pedal from the reference point). By controlling the braking force based on this, the vehicle 1 is controlled to be decelerated.

The braking force for decelerating the vehicle 1 increases as the accelerator opening of the accelerator pedal 21 approaches 0, and becomes maximum when the accelerator opening is 0. Therefore, when the driver operates the accelerator pedal 21 during the automatic speed control as described above, the vehicle 1 is decelerated to a certain speed or less, and the accelerator opening degree indicating the operating state of the accelerator pedal 21 becomes 0. , The vehicle control device (VCU) 2 outputs a stop command to the ECU 3.

The ECU 3 determines whether or not a stop command has been received from the VCU 2 in step S11 of FIG. Upon receiving the stop command, the ECU 3 determines that the vehicle 1 has shifted from the torque control to the speed control described above, and subsequently executes the process for stopping.

That is, in step S13, the ECU 3 acquires the speed of the vehicle 1 from the speed calculation unit 8. The speed of the vehicle 1 is obtained from, for example, the rotation speed of the electric motor 15 or the rotation speeds of the wheels 13a and 13b.

In the subsequent step S15, the ECU 3 obtains acceleration data by time-differentiating the vehicle speed acquired in step S13 by the acceleration calculation unit 31 of the acceleration calculation unit 5. Then, in the following step S17, the frequency component corresponding to the mechanical resonance frequency of the vehicle 1 is reduced by the notch filter 33 with respect to the acceleration signal output from the acceleration calculation unit 31 (filter process 1).

Further, in step S19, the ECU 3 reduces the signal component of a certain frequency or higher by the low-pass filter 35 from the output signal from the notch filter 33 (filter processing 2) to obtain acceleration data.

In step S21, the ECU 3 inputs the target acceleration obtained by the calculation and processing in steps S15 to S19 into the target speed setting unit 7, and back-calculates (integrates) the target acceleration to calculate the target speed.

In the following step S23, the ECU 3 transmits the target speed calculated in step S21 to the MCU 9 as a control signal of the electric motor 15, and controls the speed (speed control) so that the electric motor 15 rotates according to the target speed.

In step S25, the ECU 3 determines whether or not the vehicle 1 equipped with the electric motor 15 rotationally driven according to the target speed has stopped (the speed has become 0). Then, the control of the electric motor 15 according to the target speed is executed until the vehicle 1 stops (the determination in step S25 is YES).

In this way, in a vehicle performing automatic speed control, when the vehicle is stopped by depressing the accelerator pedal that has been depressed, the speed calculation when the speed control is started is based on the target acceleration. By calculating the target speed, it is possible to prevent the driver from feeling uncomfortable.

This is because when shifting from torque control to speed control while the vehicle is decelerating without stepping on the brake, if the target speed is calculated based on the acceleration while the brake is stepped on, the driver will feel uncomfortable. be.

That is, if there is a mechanical fluctuation in the signal to be processed at the switching timing when shifting from torque control to speed control, deceleration with continuous connection cannot be performed. Therefore, when the vehicle is stopped, the driver feels uncomfortable and cannot obtain a good driving feeling.

Therefore, in the electronic control device for vehicles according to the present embodiment, a notch filter and a low-pass filter having different frequency characteristics are used to reduce unnecessary noise signal components from the acceleration data from the acceleration calculation unit to perform speed control. It controls to determine the target acceleration when it is started (that is, when the driver's foot is released from the accelerator pedal). This is to avoid a situation in which the target speed is unknown in the control from that point to the stop without the acceleration information when decelerating.

In the above embodiment, the output signal from the acceleration calculation unit 31 is input to the notch filter 33 to reduce the mechanical resonance frequency, and the low-pass filter 35 reduces the sensor noise from the output signal from the notch filter 33. However, it is not limited to this.

For example, as shown in FIG. 5, the acceleration calculation unit 31 calculates the acceleration based on the signal obtained by filtering the vehicle speed signal (speed data) with the notch filter 33, and the calculated acceleration signal is obtained. Filter processing by the low-pass filter 35 may be performed.

By processing the velocity data in the order of notch filter processing → acceleration calculation → low-pass filter processing in this way, it is possible to improve the acceleration calculation accuracy based on the signal with the unnecessary mechanical resonance frequency component reduced. can.

As described above, the vehicle electronic control device according to the present embodiment has a signal within a certain frequency band due to the notch filter from the acceleration signal, that is, unnecessary mechanical resonance generated due to the mechanical structure of the vehicle or the like. It has a configuration in which the frequency component is reduced, and further, the low-pass filter obtains acceleration data having a signal component having a certain frequency or higher than the output signal of the notch filter, that is, noise from various sensors is reduced.

Therefore, when the vehicle is decelerating during automatic speed control, a noise signal that interferes with vehicle travel control is generated from the acceleration data obtained by time-differentiating the speed data by using a notch filter and a low-pass filter together. Since it is reduced, the characteristics of each filter can be effectively used to calculate a more appropriate target acceleration, and the vehicle can be controlled and smoothly stopped according to the target speed.

At this time, by setting the cutoff frequency of the low-pass filter higher than the notch frequency of the notch filter, it is possible to efficiently reduce unnecessary signal components corresponding to the frequency of the sensor noise included in the acceleration data.

1 Vehicle 2 Vehicle Control Unit (VCU)
3 Electronic control unit (ECU)
5 Acceleration calculation unit 7 Target speed setting unit 8 Speed calculation unit 9 Motor control unit (MCU)
10 Inverter circuit 11 Transmission 13a, 13b Wheels 15 Electric motor 17 Position detector 21 Accelerator pedal 23 Brake pedal 25 Brake control unit 31 Acceleration calculation unit 33 Notch filter 35 Low-pass filter

Claims (11)

A control device that controls the running of a vehicle according to a target speed.
A vehicle speed detection unit that detects the speed of the vehicle,
An acceleration calculation unit that calculates acceleration based on the vehicle speed detected by the vehicle speed detection unit,
A notch filter that removes a predetermined frequency signal component from the output signal of the acceleration calculation unit, and
A low-pass filter that reduces signal components above a certain frequency from the output signal of the acceleration calculation unit,
A means for setting a target acceleration based on the acceleration after filtering by the notch filter and the low-pass filter, and
With
A control device that calculates the target speed at the time of deceleration of the vehicle by using the target acceleration. The control device according to claim 1, wherein the cutoff frequency of the low-pass filter is higher than the notch frequency of the notch filter. The control device according to claim 2, wherein the low-pass filter is a primary low-pass filter. The control device according to claim 2 or 3, wherein the cutoff frequency is determined according to the frequency of noise generated from the sensor group including the vehicle speed detection unit. The control device according to claim 2, wherein the notch frequency is determined according to the mechanical resonance frequency of the vehicle. The control device according to claim 5, wherein the mechanical resonance frequency is the notch frequency. The notch filter is represented by Q = ω ₀ / (ω _{2 -ω 1} ), where _{ω 0} is the notch frequency and ω ₁ and ω ₂ (ω ₁ <ω ₀ <ω ₂ ) are the frequencies that give the half-value width. The control device according to claim 6, wherein the Q value is 0.7 to 0.8. The acceleration calculation unit calculates the acceleration based on the signal obtained by filtering the vehicle speed signal detected by the vehicle speed detection unit with the notch filter, and the low-pass filter is used for the calculated acceleration signal. The control device according to any one of claims 1 to 7, wherein the filtering process is performed. An inverter device that drives an electric motor
A means for generating a torque command signal of the electric motor so as to follow a target speed generated by the control device according to any one of claims 1 to 8.
A means for driving and controlling the electric motor by the torque command signal, and
Inverter device equipped with. An automobile provided with the inverter device according to claim 9. It is a control method that controls the running of the vehicle according to the target speed.
The process of detecting the speed of the vehicle and
A step of calculating the acceleration based on the vehicle speed detected in the detection step, and a step of calculating the acceleration.
A first filter processing step of removing a predetermined frequency component from the acceleration signal calculated in the calculation step by a notch filter, and
A second filter processing step of reducing a signal component having a certain frequency or higher by a low-pass filter from the acceleration signal after the filter processing in the first filter processing step.
A step of setting a target acceleration based on the acceleration after filtering by the second filtering step, and a step of setting the target acceleration.
A step of calculating the target speed at the time of deceleration of the vehicle using the target acceleration determined in the setting step, and a step of calculating the target speed at the time of deceleration of the vehicle.
Control method including.

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