JP7438754B2 - Control device - Google Patents

Description

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

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

Patent Document 1 is designed in view of the problem that a waveform obtained by time-differentiating the vehicle speed detected by a vehicle speed sensor becomes oscillatory, and that if the waveform is directly applied to vehicle control as vehicle acceleration, a control problem will occur. This patent discloses a technique that reduces high-frequency noise by performing low-pass filter processing on the time differential value of vehicle speed, and reduces steady-state vibration by performing slope restriction processing on the high-frequency noise reduction value.

Japanese Patent Application Publication No. 2016-200564

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

Further, since the acceleration data obtained from the instantaneous value of the velocity includes mechanical resonance noise, if the acceleration data is used as it is, the control section at the next stage may misrecognize the acceleration.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a control device that can accurately calculate 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 problems. That is, a first exemplary invention of the present application is a control device that controls running of a vehicle according to a target speed, and includes a vehicle speed detection section that detects the speed of the vehicle, and a vehicle speed detected by the vehicle speed detection section. an acceleration calculation unit that calculates acceleration based on the acceleration calculation 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 of a certain frequency or higher from the output signal of the acceleration calculation unit. and 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 when the vehicle is decelerated using the target acceleration. It is characterized by

A second exemplary invention of the present application is an inverter device that drives an electric motor, the torque of the electric motor being adjusted to follow the target speed generated by the control device according to the first exemplary invention. The electric motor is characterized by comprising means for generating a command signal, and means for driving and controlling the electric motor using the torque command signal.

A third exemplary invention of the present application is an automobile, which is characterized by being equipped with the inverter device according to the second exemplary invention.

A fourth exemplary invention of the present application is a control method for controlling the running of a vehicle according to a target speed, which includes a step of detecting the speed of the vehicle, and calculating an acceleration based on the vehicle speed detected in the detecting step. a first filtering step of removing a predetermined frequency component from the acceleration signal calculated in the calculation step using a notch filter; and a step of removing a predetermined frequency component from the acceleration signal calculated in the first filtering step using a low-pass filter a second filter processing step for reducing signal components having a certain frequency or higher; 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. and calculating the target speed at the time of deceleration of the vehicle using the method.

According to the present invention, speed control is performed in the control device based on an acceleration signal from which both mechanical resonance frequency components and sensor noise components caused by the mechanical structure of the vehicle are removed. Good riding comfort can be obtained at times.

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

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

In FIG. 1, a vehicle 1 includes an electronic control unit (ECU) 3 which is a motor control device, a vehicle control unit (VCU) 2 which is an upper control device (superior controller) of the ECU 3, and an ECU 3. A motor control unit (MCU) 9 that drives an electric motor 15 according to a control signal, a transmission 11 that is connected to the electric motor 15 and transmits its rotational driving force to wheels 13a and 13b, and the like are provided.

Vehicle 1 is, for example, an electric vehicle (EV), and includes a battery (not shown) that supplies drive power to electric motor 15 . Furthermore, the vehicle 1 is a vehicle that can perform automatic speed control of acceleration, deceleration, and stopping by operating a single pedal.

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 driver's pedal stroke is from a predetermined position, the vehicle is stopped. This is a control that decelerates the vehicle when it accelerates and then depresses the pedal back from a predetermined position.

The ECU 3 is configured by, for example, a microcomputer that receives various signals and controls the entire ECU 3. The ECU 3 transmits output signals corresponding to acceleration requests, deceleration requests, and stop requests to the vehicle 1 to the MCU 9 to drive and control the electric motor 15.

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

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

Note that 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 determines the rotation angle of the electric motor 15 based on a signal from a position detector 17 placed near 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 detection accuracy of the rotational position and the durability under high temperatures can be improved compared to a Hall element or the like. On the other hand, when the Hall element 17 is used, the configuration can be made cheaper than 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) is detected by an accelerator opening sensor (not shown). The VCU 2 generates signals for controlling acceleration, deceleration, etc. of the vehicle 1 based on 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 corresponding to the brake operation amount from a brake stroke sensor (not shown) to the brake control unit 25. The brake control unit 25 controls a brake mechanism 27 including a brake pad, a hydraulic mechanism, etc. to stop the vehicle 1.

Note that the brake control may also include regenerative brake control that generates braking force based on the amount of regeneration 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 performs torque control (torque control) to control the torque of the electric motor 15 to follow a torque command value. The speed control (speed control) that is controlled (maintained) so that the actual rotation speed of the electric motor 15 becomes the target rotation speed is switched.

During 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 amount of depression of the accelerator pedal 21 and the vehicle speed, and issues the command. It is input to the ECU 3 as 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 the electric motor 15.

On the other hand, during speed control, the acceleration calculation section 5 of the ECU 3 calculates a target acceleration from speed data input from the VCU 2, as will be described later. The calculated target acceleration is input to the target speed setting section 7. The MCU 9 controls the rotational speed of the electric motor 15 based on the target speed from the target speed setting section 7.

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

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

Although there may be multiple mechanical resonance frequencies due to the structure of the vehicle 1 or variations in the weight loaded on the vehicle 1, 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 and pinpoint reduced.

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

FIG. 3 shows an example of 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 a damping characteristic that sets the above-mentioned mechanical resonance frequency (for example, a frequency around 10 Hz) as a notch frequency (ω ₀ ).

As shown by the solid line in FIG. 3, the notch filter 33 has a minimum amplitude gain at the notch frequency ω ₀ , thereby reducing the notch frequency component and its neighboring frequency components from the input signal and outputting the result.

The notch frequency ω ₀ is the center frequency that provides attenuation to the input signal, and the frequency characteristics of the notch filter 33 can be expressed by the Q value, which is a parameter indicating the notch width, as shown in equation (1) below. .

Q=ω ₀ /(ω ₂ −ω ₁ ) … (1)

ω ₂ −ω ₁ in equation (1) is called the half width. As shown in Figure 3, the frequency ω ₁ that gives the half-width is lower than ω ₀ , and is the frequency where the amplitude is half the value of the resonance peak (the frequency where the amplitude gain in the stop band is -3 dB of the gain in the pass band). It is. Similarly, the frequency ω ₂ that provides the half-width is higher than ω ₀ and is the frequency at which the amplitude is half the value of the resonance peak (the frequency at which the amplitude gain in the stop band is −3 dB of the gain in 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 of a certain frequency or higher generated by the various sensors described above from the signal output from the notch filter 33. Here, as shown by the dashed 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, several hundred Hz, more specifically a frequency around 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. The low-pass filter 35 can achieve a filter performance (attenuation rate) of -20 dB/dec by using, for example, a first-order low-pass filter. Note that the order of the low-pass filter 35 is not limited to first order.

Furthermore, by using a low-pass filter, phase lag in filter processing can be suppressed, processing (calculation) load can be suppressed, and unnecessary sensor noise included in acceleration data can be reduced.

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

Next, vehicle stopping processing in the control device according to the present embodiment will be explained. FIG. 4 is a flowchart chronologically showing vehicle stopping processing in the control device according to the present embodiment.

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 controls the amount of the accelerator pedal 21 to be depressed (for example, the amount of return of the accelerator pedal from the reference point). Control is performed to decelerate the vehicle 1 by controlling the braking force based on this.

The braking force that decelerates the vehicle 1 increases as the accelerator opening degree of the accelerator pedal 21 approaches 0, and becomes maximum when the accelerator opening degree is 0. Therefore, when the driver operates the accelerator pedal 21 during automatic speed control as described above, and 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 unit (VCU) 2 outputs a stop command to the ECU 3.

In step S11 of FIG. 4, the ECU 3 determines whether or not a stop command has been received from the VCU 2. When a stop command is received, the ECU 3 determines that the vehicle 1 has shifted from the above-mentioned torque control to speed control, and thereafter executes processing toward stopping.

That is, the ECU 3 obtains the speed of the vehicle 1 from the speed calculation section 8 in step S13. The speed of the vehicle 1 is determined, for example, from the rotational speed of the electric motor 15 or the rotational speed of the wheels 13a and 13b.

In the subsequent step S15, the ECU 3 uses the acceleration calculation unit 31 of the acceleration calculation unit 5 to time-differentiate the vehicle speed acquired in step S13 to obtain acceleration data. Then, in the subsequent step S17, the notch filter 33 reduces the frequency component corresponding to the mechanical resonance frequency of the vehicle 1 with respect to the acceleration signal output from the acceleration calculation unit 31 (filter processing 1).

Further, in step S19, the ECU 3 uses the low-pass filter 35 to reduce signal components of a certain frequency or higher from the output signal from the notch filter 33 (filter processing 2), and obtains acceleration data.

In step S21, the ECU 3 inputs the target acceleration obtained through the calculations and processing in steps S15 to S19 above to the target speed setting section 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 for the electric motor 15, and performs speed control so that the electric motor 15 rotates according to the target speed.

In step S25, the ECU 3 determines whether the vehicle 1 equipped with the electric motor 15 that is 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 (determination is YES in step S25).

In this way, in a vehicle that is performing automatic speed control, when the accelerator pedal is depressed and the vehicle is stopped, the speed calculation when speed control is started is based on the target acceleration. To prevent a driver from feeling uncomfortable by calculating a target speed.

This is because when transitioning from torque control to speed control while the vehicle has been decelerating without pressing the brakes, the driver will feel a sense of discomfort if the target speed is calculated using the acceleration with the brakes pressed. be.

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

Therefore, in the vehicle electronic control device 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, and thereby speed control is performed. Control is performed to determine the target acceleration when the vehicle is started (that is, when the driver's foot leaves the accelerator pedal). This is to avoid a situation where, if there is no acceleration information at the time of deceleration, the target speed will not be known in the control from that point to stopping.

Note that 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 is configured to reduce 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 acceleration based on a signal obtained by filtering the vehicle speed signal (speed data) with the notch filter 33, and Filtering processing using a low-pass filter 35 may also be performed.

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

As explained above, the vehicle electronic control device according to the present embodiment uses a notch filter to extract signals within a certain frequency band from acceleration signals, that is, unnecessary mechanical resonances generated due to the mechanical structure of the vehicle, etc. It has a configuration in which acceleration data is obtained by reducing frequency components and further reducing signal components having a certain frequency or higher than the output signal of the notch filter, that is, noise from various sensors using a low-pass filter.

Therefore, when the vehicle is decelerating during automatic speed control, a notch filter and a low-pass filter are used in combination to differentiate the speed data with respect to time.Acceleration data is used to detect noise signals that interfere with vehicle travel control. Therefore, by effectively using the characteristics of each filter, a more appropriate target acceleration can be calculated, and the vehicle can be controlled according to the target speed and stopped smoothly.

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

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 section 31 Acceleration calculation section 33 Notch filter 35 Low-pass filter

Claims (11)

A control device that controls 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 section;
a low-pass filter that reduces signal components of a certain frequency or higher from the output signal of the acceleration calculation section;
means for setting a target acceleration based on the acceleration after filtering by the notch filter and the low-pass filter;
Equipped with
A control device that calculates the target speed during deceleration of the vehicle 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 first-order 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 by a sensor group including the vehicle speed detection section. The control device according to claim 2, wherein the notch frequency is determined according to a 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 expressed as Q=ω ₀ /(ω ₂ −ω ₁ ), where the notch frequency is ω ₀ and the frequencies giving the half width are ω ₁ , ω ₂ (ω ₁ <ω ₀ <ω ₂ ). 7. The control device according to claim 6, wherein the Q value is 0.7 to 0.8. The acceleration calculation unit calculates acceleration based on a signal obtained by filtering the vehicle speed signal detected by the vehicle speed detection unit with the notch filter, and the calculated acceleration signal is processed by the low-pass filter. The control device according to any one of claims 1 to 7, which performs filter processing. An inverter device that drives an electric motor,
Means for generating a torque command signal for the electric motor so as to follow the target speed generated by the control device according to any one of claims 1 to 8;
means for driving and controlling the electric motor using the torque command signal;
An inverter device comprising: An automobile comprising the inverter device according to claim 9. A control method for controlling running of a vehicle according to a target speed, comprising:
detecting the speed of the vehicle;
a step of calculating acceleration based on the vehicle speed detected in the detection step;
a first filter processing step of removing a predetermined frequency component from the acceleration signal calculated in the calculation step using a notch filter;
a second filtering step of reducing signal components of a certain frequency or higher using a low-pass filter from the acceleration signal after filtering in the first filtering step;
a step of setting a target acceleration based on the acceleration after filtering in the second filtering step;
calculating the target speed when the vehicle is decelerated using the target acceleration determined in the setting step;
A control method comprising:

Images