WO2015001849A1

WO2015001849A1 - Electric-vehicle braking control device

Info

Publication number: WO2015001849A1
Application number: PCT/JP2014/063014
Authority: WO
Inventors: 宮崎　英樹
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2013-07-05
Filing date: 2014-05-16
Publication date: 2015-01-08
Also published as: JP2016165165A

Abstract

The present invention does not detect the actual torque of a motor when regeneratively braking, and does not compensate for the actual torque according to a source of motor error or the like. An electric-vehicle braking control device equipped with an inverter control unit for controlling the power supplied by the battery, a motor for controlling the torque for driving or braking a drive wheel by using the inverter control unit, and a braking control unit (9) for controlling the allotment of the braking torque from regenerated power regenerated in the battery by the motor when braking and the braking torque caused by electronically controlled friction brakes, the electric-vehicle braking control device being characterized in that the inverter control unit is equipped with: torque estimation units (57, 58, 59, 60) for estimating the actual torque of the motor from the regenerated power for regenerating the motor; and a feedback control unit for feeding back the braking torque to be outputted by the motor on the basis of the difference between a braking torque command value indicated to the motor by the braking control unit (9) and the actual torque value estimated by the torque estimation units (57, 58, 59, 60).

Description

Electric vehicle braking control device

The present invention relates to a braking control device for an electric vehicle that is regeneratively braked by a motor.

In an electric vehicle or a hybrid vehicle, a motor is mounted as a power source of the vehicle, and an inverter for controlling the electric power supplied to the motor is provided. The motor is the main power, and has a function of converting the kinetic energy of the vehicle during regenerative braking into electricity and regenerating it in the battery as well as driving the vehicle.

Paying attention to the control command at the time of braking, the regenerative braking torque command for the front and rear wheel motors is calculated by the braking control unit provided in the controller of the vehicle, and this regenerative braking torque command is transmitted to the inverter control unit related to motor control. Thus, the regenerative braking torque of the front and rear wheel motors is controlled. The electronically controlled friction brake calculates a command related to the friction braking torque by a brake controller in accordance with a command from the brake control unit, and controls the four-wheel electronically controlled friction brake to follow the command. At the time of braking, regenerative cooperative control is performed in which the battery is regenerated by the motor and immediately before the vehicle finally stops, the friction braking by the electronically controlled friction brake is applied.

On the other hand, the following (1) to (3) are known as error factors relating to the output torque of the motor.
(1) In a permanent magnet type motor, the amount of magnetic flux decreases due to the temperature change of the magnet, and the torque decreases according to the characteristics of the magnet even when the same current is applied.
(2) When a neodymium magnet is used, permanent demagnetization may occur at a high temperature. After that, the amount of magnetic flux decreases, and the torque decreases from the normal case even when the same current is applied.
(3) There is an error or the like of the control current sensor provided in the inverter.
There is a possibility that an error of about 10 to 20% may occur due to the overlap of the above three error factors.

However, the driving / braking torque controlled by the motor is characterized by being 100 times more responsive than the engine vehicle torque. It is desired to automatically perform fine control according to the degree of friction of the road surface by utilizing this high responsiveness.

Here, focusing on the accuracy with respect to the regenerative braking torque command calculated by the braking control unit, the control device for the electric vehicle does not include means for detecting the actual torque of the motor related to regenerative braking. The reason is that an expensive torque sensor is required to measure the torque with respect to the mechanical output of the motor. (Patent Document 1)

JP 2008-238836 A

In Patent Document 1, the actual torque of the motor related to regenerative braking is not detected, and a function for compensating the actual torque according to an error factor of the motor or the like is not described.

A braking control device for an electric vehicle according to the present invention will be described with reference numerals in the drawings of the embodiments. The braking control device for an electric vehicle according to claim 1 is controlled by an inverter control unit 10 that controls electric power supplied from a battery, and the inverter control unit, and applies driving torque to driving wheels during powering operation to perform regenerative operation. Sometimes a motor that applies regenerative braking torque to the drive wheels, and braking control that controls the sharing of the regenerative braking torque obtained by the regenerative power regenerated from the motor to the battery during braking and the friction braking torque by the electronically controlled friction brake Part 9. Further, the inverter control unit 10 further includes

torque estimation units

57, 58, 59, 60 for estimating the actual torque τ _{0 of the} motor from regenerative power regenerated to the battery, and the brake control unit 9 provided to the motor. Feedback for feedback control of the regenerative braking torque output by the motor from the difference Δτ between the instructed regenerative braking torque command value τ ^ and the actual torque value τ ₀ estimated by the

torque estimation units

57, 58, 59, 60. And a control unit 61.
The above reference numerals are only examples provided for reference, and the present invention is not limited thereto.

According to the present invention, the actual torque of the motor is detected without using an expensive torque sensor, the difference between the detected actual torque and the torque command value is fed back to compensate for the actual torque, and fine automatic torque adjustment is performed. Can be possible.

It is a block diagram which shows the system configuration | structure of the electric vehicle in 1st Embodiment. It is a functional block diagram showing torque feedback control. It is a block diagram which shows the system configuration | structure of the electric vehicle in 2nd Embodiment. It is a flowchart regarding the torque correction of a motor. It is a flowchart regarding abnormality determination at the time of braking. It is a characteristic view regarding sharing of the braking torque by a motor and an electronically controlled friction brake. It is a characteristic view showing the change of the magnet temperature regarding a motor.

(First embodiment)
FIG. 1 is a block diagram showing a system configuration of an electric vehicle. In this example, the electric vehicle is an electric vehicle, and the shaft output torque of the motor 1 is transmitted to the left and

right drive wheels

4A, 4B via the reduction gear 2 and the differential gear 3. The

drive wheels

4A and 4B are provided with

brakes

5A and 5B, respectively.

The

brakes

5A and 5B are electronically controlled friction brakes. When the driver steps on the brake pedal 6, the pedaling force is transmitted to the negative pressureless brake 7, and the torque of the motor built in the negative pressureless brake 7 is used together with the pedaling force. The applied force increases the hydraulic pressure for braking. The brake hydraulic pressure is distributed to the four wheels by an ESC (Electronic Stability Control) 8 having a lock prevention function, and the movable portions of the

brakes

5A and 5B are driven by the hydraulic pressure to brake the

drive wheels

4A and 4B. That is, a mechanical friction braking torque is applied.

Further, the depression amount of the brake pedal 6 by the driver is converted into a braking torque request signal relating to the braking force. This braking torque request signal is transmitted to the vehicle controller 9. As will be described later, the vehicle controller 9 divides the braking torque request signal into two types, that is, the regenerative braking torque request value by the motor 1 and the friction braking torque request value by the electronically controlled friction brake, and the regenerative braking torque request value, The friction braking command value is calculated and output. The friction braking command value is transmitted from the vehicle controller 9 to the negative pressureless brake 7 as a braking command signal 20. The regenerative braking torque request value is transmitted to the motor controller 14 as a braking request value signal 21. As will be described later, the motor controller 14 generates an IGBT drive pulse signal to drive the IGBT to regenerate the motor 1. Thereby, the motor 1 is regeneratively operated to obtain a regenerative braking force.

The vehicle controller 9 also receives a power running torque command signal from the accelerator pedal 62, and calculates a power running torque command value based on the power running torque command signal and outputs it to the motor controller 14 during power running. As will be described later, the motor controller 14 generates an IGBT drive pulse signal to drive the motor 1 so as to drive the motor 1. As a result, the motor 1 is powered.

Note that the judgment function for sharing the braking torque into two types, that is, the regenerative braking torque by the motor 1 and the friction braking torque by the electronically controlled friction brake, is not only performed by the vehicle controller 9 but also the control unit of the negative pressureless brake 7. (Not shown) may be performed, or may be performed by another controller mounted on the same vehicle. In either case, it functions as a braking control unit.

In this embodiment, although the case where the motor 1 is a permanent magnet type motor is described, it is not necessarily limited to a permanent magnet type motor.

1, the converter that controls the power running drive or the regenerative drive of the motor 1 is an inverter control unit 10, and a main circuit 11 is provided inside the inverter control unit 10. The main circuit 11 is configured by connecting six power devices IGBTs (Insulated Gate Bipolar Transistors) and diodes to a three-phase bridge circuit. The two high voltage terminals of the main circuit 11 are connected to the positive electrode and the negative electrode of the battery 12, and the inverter control unit 10 converts the voltage supplied from the battery 12 into an AC voltage and supplies it to the motor 1.

A capacitor 13 is provided between the main circuit 11 and the battery 12, and the capacitor 13 functions as an energy buffer when the main circuit 11 supplies a transient current for a short time. That is, once the energy stored in the capacitor 13 is provided immediately, the battery 12 is discharged from the battery 12 to replenish the consumed energy.

The above-described motor controller 14 is further provided inside the inverter controller 10. As described above, the motor controller 14 applies a gate drive pulse to the IGBT of the main circuit 11 so that the motor 1 outputs a desired torque based on the torque command value 21 input from the vehicle controller 9. It has a function.

The motor controller 14 detects the rotor magnetic pole position detected by the magnetic pole position detector 15 provided in the motor 1, and drives and controls the IGBT according to the position detection signal. Each of the three-phase output lines from the inverter control unit 10 to the motor 1 is provided with a first current detector 16, and the three-phase current detection value is transferred from the first current detector 16 to the motor controller 14. The three-phase currents iu, iv, and iw are converted into two components of id and iqｉ in the motor controller 14 and used. The torque control of the motor 1 is a so-called vector control in which two components of the current id and iq are set to values according to a desired torque.

The second current detector 17 is provided in the wiring connecting the battery 12 and the inverter control unit 10, and the output of the second current detector 17 is transmitted to the battery state monitoring device 18. The battery state monitoring device 18 detects not only the current information obtained from the second current detector 17 but also the voltage between the positive and negative electrodes of the battery 12, the temperature of the battery, etc., and the remaining capacity of the battery and the allowable charging current. Estimate the discharge current. The state monitoring device 18 of the battery 12 transmits the detected information to the vehicle controller 9, and this signal is represented by a battery state detection signal 22 in FIG.

A third current detector 19 is provided in the wiring connecting the electrodes of the battery 12 and the capacitor 13, and the signal is taken into the motor controller 14. As will be described later, the motor controller 14 measures the voltage between the positive and negative electrodes of the capacitor 13 and multiplies the detected voltage by the DC current detected by the third current detector 19 to calculate the amount of power. Have. This arithmetic expression is an expression (1) described later.

Furthermore, the motor controller 14 calculates the copper loss of the motor 1 from the current flowing through the motor 1. This arithmetic expression is an expression (2) described later. The motor controller 14 adds the copper loss to the previous electric energy calculation result, divides this addition result by the angular velocity of the motor 1 obtained by the magnetic pole position detector 15, and estimates the actual torque during braking of the motor 1. Also have. This arithmetic expression is an expression (3) described later.

Hereinafter, the operation of the braking control apparatus according to the first embodiment that performs feedback control of regenerative braking torque using the actual torque estimated value obtained during regenerative braking will be described with reference to FIG. In FIG. 2, the control executed by the motor controller 14 in the inverter control unit 10 is shown by a functional block diagram. In addition, the main circuit 11, the motor 1, the magnetic pole position detector 15, and the first current detector 16 are provided. The structure is shown.

The motor controller 14 functionally includes a first current command calculation unit 51 that calculates the two-phase current commands id and iq during power running based on the power running torque command τ ^ transmitted from the vehicle controller 9 during power running, A command of the second current command calculation unit 56 that calculates the two-phase current commands id and iq at the time of regeneration based on the braking torque command τ ^ transmitted from the vehicle controller 9 at times, and a command of the first current command calculation unit 51 during powering operation And a switcher 52 that selects a command of the second current command calculation unit 56 during regenerative operation.

The motor controller 14 also includes a three-phase two-phase converter 55 that converts the three-phase AC signals iu, iv, iw of the motor 1 detected by the first current detector 16 into two-phase current signals id, iq, and 3 A comparator 53 is provided that takes a deviation between the id and iq current signals converted by the phase-to-phase converter 55 and the current command value selected by the switch 52. The current command deviation that is the output of the comparator 53 is input to the current control unit 54, and the current control unit 54 performs a vector operation to calculate a control current value and inputs the control current value to the PWM generation unit 50. The PWM generator 50 generates an IGBT drive pulse based on the input control current value and applies the drive pulse to the gate of the IGBT.

The motor controller 14 further includes a regenerative power calculation unit 57, an actual torque calculation unit 60, a copper loss calculation unit 58, and an angular velocity calculation unit 59 as a torque estimation unit.
The regenerative power calculator 57 uses the product of the detected amount V ^{* of the} voltage between the positive and negative electrodes of the capacitor 13 and the detected amount I ^* of the direct current detected by the third current detector 19 during regeneration. Is calculated from the equation (1).
P = V ^* × I ^* (1)
Copper loss calculation unit 58, the motor current id which is the coordinate transformation, by multiplying the coil resistance R _M of the motor 1 the two components of iq each squared sum seek copper loss Wc from equation (2).
Wc = (id ² + iq ² ) × R _M (2)
The actual torque calculation unit 60 calculates the motor angular velocity ω calculated by the angular velocity calculation unit 59 to which the rotor magnetic pole position detection signal is input, the regenerative power amount P calculated by the regenerative power calculation unit 57, and the copper loss calculation unit 58. The actual torque estimated value τ ₀ is obtained from the equation (3) using the copper loss Wc.
τ ₀ = (P + Wc) / ω (3)

The operation of the motor controller 14 during powering operation will be described.
In the power running operation, the current command value of the first current command calculation unit 51 is selected by the switch 52 so that the actual torque feedback is not performed. As described above, the motor 1 is provided with the magnetic pole position detector 15 and the first current detector 16. The output of the magnetic pole position detector 15 is transmitted to a current control unit 54 that performs vector control. The output of the first current detector 16 is coordinate-converted from a three-phase current to a two-component current of id and iq by a three-phase to two-phase converter 55.

The first current command calculation unit 51 receives the input of the drive torque command τ ^ from the vehicle controller 9 and calculates and outputs the two-phase current command values id, iq corresponding to the drive torque command τ ^. The current command value is compared by the comparator 53 with the components of id _detec and iq _detec whose coordinates are converted by the three-phase / two-phase converter 55, and the current controller 54 controls the control current value according to the deviations Δid and Δiq. Is a vector operation. In accordance with the vector calculation result, the PWM generator 50 generates a gate drive pulse for switch-controlling the IGBT of the main circuit 11.

The operation of the motor controller 14 during regenerative operation will be described.
In the regenerative operation, the current command value of the second current command calculation unit 56 is selected by the switch 52 so that actual torque feedback is performed. And the regenerative electric power calculating part 57 calculates the regenerative electric energy P from said (1) Formula. Further, the copper loss calculation unit 58 calculates the copper loss Wc of the motor 1 from the above equation (2). Further, the angular velocity calculation unit 59 obtains the angular velocity ω of the motor 1 from the signal detected by the magnetic pole position detector 15. Using the values of the regenerative power P, the copper loss Wc, and the angular velocity ω, the actual torque calculation unit 60 obtains the actual torque estimated value τ ₀ from the above equation (3).

The comparator 61 obtains a deviation Δτ between the actual torque estimated value τ ₀ calculated by the actual torque calculation unit 60 during regenerative braking and the regenerative braking torque command τ ^ calculated and output by the vehicle controller 9 during regenerative braking. The second current command calculation unit 56 calculates and outputs the two-phase current command values id and iq in consideration of the deviation Δτ obtained from the comparator 61. The current command values id and iq calculated by the second current command calculation unit 56 and selected by the switch 52 are the id _detec and iq _detec components converted by the three-phase / two-phase conversion unit 55 and the comparator 53. The difference between the two is calculated. In response to this deviation, the current control unit 54 performs a vector operation on the control current value, and in accordance with the result, the PWM generation unit 50 generates a gate drive pulse for switch-controlling the IGBT.

By the above control, the actual torque value during regenerative braking is accurately controlled to the designed torque command value. In particular, as in the case of a regenerative cooperative brake device, when the required braking torque value due to depression of the brake pedal is shared between the friction torque and the regenerative torque, the braking performance is improved.

FIG. 6 is a characteristic diagram regarding the sharing of braking torque by the motor 1 and the electronically controlled friction brake. During driving, the vehicle decelerates due to running resistance, so the driver operates the accelerator to compensate for this, so it is rare for the motor 1 to maintain a constant torque state. In particular, as in a hybrid vehicle, when the motor 1 and the engine are used for driving, the motor torque is finely controlled according to the engine output state. On the other hand, at the time of braking, when the braking control unit commands the braking torque by the motor 1 according to the braking operation by the driver, the vehicle speed decreases with time so that the deceleration acceleration is substantially constant.

As shown in FIG. 6, there is a situation where the motor 1 maintains a constant braking torque for several seconds during braking, and it is a suitable timing during braking in order to detect the actual torque of the motor 1. In the first embodiment described with reference to FIG. 2, this timing is suitable for detecting the actual torque.

The torque controlled by the motor 1 during braking is the sum of the amount of power regenerated in the battery and the power loss consumed by the motor 1 and the inverter control unit 10. The power loss of the motor 1 is dominated by the copper loss of the coil, the iron loss of the stator and the rotor core, and the eddy current loss of the permanent magnet. Here, the core iron loss and the permanent magnet eddy current loss increase as the motor 1 rotates more rapidly.

FIG. 7 is a characteristic diagram showing changes in motor rotation speed and magnet temperature. FIG. 7 shows an example showing a behavior in which a permanent magnet rises in temperature due to eddy current loss. This example is a simulation result when the electric vehicle is continuously driven four times in the US06 mode which is a high-speed driving mode. It can be seen that the magnet temperature is 50 ° C. at the start of running, but the temperature rises to 110 ° C. when driven in four US06 modes.

On the other hand, at the time of braking, the motor 1 maintains the torque and the rotational speed decreases in proportion to the decrease in the vehicle speed. Therefore, these iron loss and eddy current loss are negligibly small compared to the copper loss. Iron loss and eddy current loss are nonlinear because the magnetic characteristics of the core and magnet are temperature-dependent, but copper loss is a motor if the temperature characteristics of the copper material that is the coil material is stored in advance. The inverter control unit 10 that detects the current can estimate it with high accuracy. As a result, the regenerative braking torque can be accurately detected by the equations (2) and (3).
Note that the temperature of the motor 1 can be easily measured by the thermocouple of the stator and the coil, but the rotor core and the magnet attached thereto are rotating at a high speed, so it is easy to measure their temperatures. Not.

As described above, the braking control device for an electric vehicle according to the first embodiment includes the inverter control unit 10. The inverter control unit 10 includes a motor control controller 14. The motor control controller 14 is configured to estimate the actual torque τ ₀ of the motor 1 from the regenerative electric power of the motor 1, and the braking control of the vehicle controller 9 and the like. Department comprises from difference Δτ of the actual torque value tau ₀ braking torque command value tau ^ and torque estimation unit instructs the motor 1 is estimated, and a feedback controller 61 for feedback control of the braking torque motor 1 outputs.

According to such a braking control device, the following operational effects can be achieved.
(1) during braking, it is possible to drive the IGBT by deviation Δτ between the torque command value tau ^ and the actual torque estimate tau ₀ to finely control the motor regenerative operation. As a result, it is possible to prevent deterioration in the accuracy of the regenerative braking force according to the depression amount of the brake pedal due to the influence of temperature or the like.

(2) The estimated value τ ₀ of the actual torque according to the first embodiment is calculated by the above-described equation (3). That is, during the regenerative operation, the regenerative electric energy P to the battery 12 is calculated by using the product of the detected amount V ^{* of the} voltage between the positive and negative electrodes of the capacitor 13 and the detected amount I ^* of the direct current detected by the third current detector 19. Is calculated. Further, the copper loss Wc is calculated by the above-described equation (2) using id and iq obtained by three-phase to two-phase conversion of the motor three-phase currents iu, iv and iw measured by the first current detector 16. . Further, the angular velocity ω of the motor is calculated based on the detection signal of the magnetic pole position detector 15, and the estimated torque value τ ₀ during braking is calculated from the above equation (3) using the electric energy P, the copper loss Wc, and the angular velocity ω. presume. By feeding back the deviation between this estimated torque value τ ₀ and the braking torque command τ ^, even when the designed regenerative braking torque cannot be obtained due to various factors, the design according to the depression amount of the brake pedal 6 is designed. Regenerative braking torque can be obtained.

(3) A switch 52 is provided so that actual torque feedback control is not performed during power running. Since the motor torque during power running varies from time to time due to various factors, actual torque feedback control is performed only during regenerative braking operation, and there is no adverse effect during power running.

The actual torque feedback control when the current command value of the second current command calculation unit 56 described above is selected is to detect the actual torque of the motor during braking in which the motor outputs a constant braking torque for several seconds. It is desirable to implement it. *

As an example of calculating the regenerative power P, the copper loss Wc, and the angular velocity ω by the motor controller 14 as the amount of change necessary for the estimation of the actual torque, the vehicle controller 9 may be used. The controller may be used.

(Second Embodiment)
At timings other than braking, the actual torque changes every moment. As described above, the factors that cause the actual torque to have an error with respect to the command value are (1) temperature, (2) demagnetization, and (3) current detection error. Therefore, a ratio (gain) between the braking torque command value τ ^ and the estimated actual torque value τ ₀ is obtained by a method similar to the control shown in FIG. 2 at the time of braking, and the correction amount (specifically, stored in the motor controller 14). The torque constant described below can be rewritten based on the above gain to maintain the same accuracy without performing actual torque feedback until the above conditions (1) to (3) change. It becomes possible.

On the other hand, the situation in which a deviation occurs in the torque is the same not only in braking but also in powering. Therefore, in order to align the torque during power running with the command value, the correction amount (torque constant) calculated and stored from the actual torque estimated value τ ₀ during braking is also used during power running. Thereby, it is possible to eliminate the influence of temperature and the like on the motor torque during power running.

The system configuration of the braking control apparatus of the second embodiment is obtained by adding a torque compensator 30 to the block diagram shown in FIG. The motor controller 14 in the inverter control unit 10 obtains a gain that is a ratio between the braking torque command value τ ^ and the actual torque estimated value τ ₀ and rewrites the correction amount stored in the motor controller 14 based on the gain. The regenerative power P, the copper loss Wc, and the angular velocity ω as the amount of change necessary for the estimation of the actual torque are calculated by the motor controller 14 according to the above formulas (1) to (3).

Although the details will be described later, the torque compensator 30 inputs a control command τ ^ that is the same as the torque command value (τ ^) 21 of the braking torque instructed to the motor controller 14 by the vehicle controller 9 as the signal 31. A signal 32 is a bidirectional signal network between the torque compensator 30 and the inverter controller 10. The torque compensator 30 further receives the remaining capacity, allowable charging current, and discharging current of the battery 12 from the state monitoring device 18 as a signal 33. The signal 34 is a signal for outputting a determination result for switching from regenerative braking by the motor 1 to braking by an electronically controlled friction brake to the negative pressureless brake 7 or the ESC 85.

Hereinafter, a second embodiment related to motor torque correction and abnormality determination during braking will be described with reference to the flowcharts of FIGS. 4 and 5. FIG. 4 is a flowchart relating to motor torque correction. FIG. 5 is a flowchart regarding abnormality determination during braking.

Steps S1 and S2 in FIG. 4 which are flowcharts relating to motor torque correction are processes executed by the torque compensator 30, and steps S3 to S9 in FIG. 4 are processes executed by the motor controller 14.

First, the input and output of the torque compensator 30 will be described. There are the following three types of

signals

31, 32, and 33 as inputs to the torque compensator 30.
(1) The first input signal 31 is a control command value τ ^ that is the same as the drive torque command value 21 instructed to the motor 1 by the vehicle controller 9 during power running.
(2) The second input signal 32 is a bidirectional network signal between the torque compensator 30 and the inverter controller 10 and exchanges various types of information. One of them is the estimated torque value τ ₀ calculated by the motor controller 14.
(3) The third input signal 33 is a signal representing the remaining capacity of the battery 12 and the allowable charge / discharge current from the state monitoring device 18 of the battery 12.
(4) The fourth input signal is a signal 35 indicating the depression angle of the brake pedal 6. Based on this signal, the torque compensator 30 calculates a depression amount and a depression speed of the brake pedal, and obtains a braking torque request value τd described later.

There are the following two types of signals as the output of the torque compensator 30.
(1) The first output signal 32 is a bidirectional signal that exchanges various information with the inverter control unit 10. For example, the torque constant φ transmitted from the motor controller 14 is included.
(2) The second output signal 34 is a determination signal for switching from regenerative braking to friction braking. The determination signal 34 is a signal for switching from regenerative braking by the motor 1 to braking by the electronically controlled friction brake in consideration of the braking torque command value 31, the estimated torque value 32, and the result of the state detection signal 33 of the battery 12. It is. This signal 34 is output to the negative pressure-less brake 7 or the controller of the ESC 8.

Hereinafter, a description will be given with reference to the flowchart of FIG. First, when the brake pedal 6 is depressed and the driver instructs braking, in step S1, the torque compensator 30 inputs monitoring information regarding the remaining capacity of the battery 12 and the allowable charging / discharging current input from the state monitoring device 18. It is obtained as 33 and it is judged whether regeneration is possible. Here, the allowable charging / discharging current is the maximum or minimum voltage that is allowed due to voltage fluctuations due to the internal resistance of the battery when the battery carries a charging current (during regeneration) or a discharging current (during powering). Represents the value under conditions that do not exceed the threshold.
If it is determined that regeneration is possible, the electronically controlled friction brake is switched to the regeneration brake by the motor 1 in step S2. Then, the processing is transferred to the motor controller 14.

Next, the motor controller 14 in the inverter control unit 10 executes the following process. In step S3, it is considered that the rotation speed N of the motor 1 is less than the speed suitable for the actual torque detection, that is, the rotation speed N is less than N ^* , and the rotation speed N of the motor 1 is stopped. It is determined whether or not the lower limit speed, that is, the lower limit rotational speed N ₀ is exceeded. In other words, in step S3, the motor rotation speed N is determined whether or not N ₀ <N <N ^※. Within this range, actual torque estimation processing, which is a feature of the present embodiment, is entered.

Here, the permanent magnet type motor generates a counter electromotive force in proportion to the rotational speed. When this counter electromotive force is much higher than the voltage of the battery 12, energy flows out from the motor 1 to the battery 12, so that normally, the flux weakening control is performed to reduce the counter electromotive force by the current component id. If it is determined in step S3 that the rotation speed of the motor 1 is in a speed range suitable for actual torque detection, the process proceeds to step S4. In the speed range where the motor rotation speed N is N ₀ <N <N ^* , the back electromotive force is also small, and the current component id may be zero. This control is performed in step S4.

Here, the torque τ of the permanent magnet type motor can be expressed by equation (4).
τ = Pn {φa · iq− (Ld−Lq) id · iq} (4)
However,
Pn is the number of pole pairs of the motor 1 φa is the amount of magnetic flux of the magnet and corresponds to a so-called torque constant.
Ld and Lq are inductances of the motor 1 in the d-axis and q-axis directions, respectively.

In a permanent magnet type motor, when the temperature of the magnet changes, the amount of magnetic flux φa decreases, and the torque decreases according to the characteristics of the magnet even when the same current is applied. When a neodymium magnet is used, permanent demagnetization may occur at a high temperature. Thereafter, the amount of magnetic flux φa is reduced, and the torque is reduced as compared with the normal case even when the same current is applied.

In step S4, when the current component id is set to zero, the right side of equation (1) is only the first term, which is expressed by equation (5).
τ ≒ Pnφa · iq (5)
That is, although the torque τ can be expressed by Pnφa · iq, since φa changes depending on the temperature of the magnet, there is an error between the actual torque and the torque calculated by the equation (5), that is, the torque as the design value. appear.
As the id used in the equation (5), the id obtained by the three-phase to two-phase converter 55 for the three-phase currents iu, iv and iw detected by the first current detector 16 is used.

In step S5, the electric energy P which the motor 1 regenerates and returns to the battery is calculated from the following equation (6).
P = V _DC × I _B (6)
In FIG. 2, the voltage between the positive and negative electrodes of the capacitor 13 is expressed by V ^* , and the detected amount of the direct current detected by the third current detector 19 is expressed by I ^* , respectively. In the flowchart of (6) and FIG. 4, V _DC and I _B are described.

In step S6, the copper loss calculation unit 58 calculates the copper loss Wc of the motor 1 from the expression (2) based on the detection amount of the first current detector 16.

In step S7, the angular velocity calculation unit 59 calculates the angular velocity ω of the motor 1 from the signal from the magnetic pole position detector 15, and calculates the actual torque estimated value τ ₀ of the motor 1 by the following equation (7).
τ ₀ = (V _DC · I _B + Wc) / ω (7)

In step S8, a torque constant φa is obtained from equation (8) derived from equations (5) and (7).
φa = τ ₀ / P _n · iq (8)

In the next step S 9, the torque constant φa that is a parameter is updated and stored in the motor controller 14. If the determination in step S3 is yes, the processing from step S4 to step S9 is repeated for each predetermined sampling period, but when the torque constant φa is updated as a result of equation (8) at the first time, In subsequent repetitions, the torque constant φa remains unchanged as long as there is no fluctuation due to temperature, and there is no particular change.

Finally, when the motor rotation speed becomes equal to or less than the predetermined value in the determination in step S3, the process proceeds to step S10, and the parameter update operation is completed.

The processing described in the flowchart of FIG. 4 is performed at each braking. Even when the motor 1 is driven at times other than braking, the parameter φa updated in the process of FIG. 4 is used, so the actual torque of the motor calculated using the above equations (4) and (5) is accurate. Can maintain high results. If the accuracy of the actual torque can be compensated in this way, it becomes possible to finely and automatically adjust the torque according to the situation in the electric vehicle.

FIG. 5 is a flowchart regarding abnormality determination during braking, and correction of the torque constant φa is performed according to the determination. The process shown in FIG. 5 is a process executed by the torque compensator 30 and is started when a pedaling force is generated from the brake pedal 6. In this figure, the following four types are dealt with regarding the braking torque.
τd: Regenerative torque request value based on the depression amount of the brake pedal 6 τ ^: Regenerative braking torque command value from the vehicle controller 9 to the motor 1
τ _0: (7) torque estimated value estimated from the equation tau ^※: AC motor torque control amount based on the command of the inverter control unit 10 where, tau ^※ is detected by the first current detector 16 of the inverter control unit 10 The torque control amount is calculated by the following equation (9) using iq calculated from the currents iu, iv, and iw.
τ ^* = Pn · φa · iq (9)

As described above, the abnormality determination flowchart of FIG. 5 is started when a depression force is applied to the brake pedal 6. First, the vehicle controller 9 assigns the braking torque corresponding to the amount of depression of the brake to the regenerative torque and the friction braking torque.
In step S11 in FIG. 5, both the regenerative torque request value τd obtained from the amount of depression of the brake pedal 6 by the signal 35 and the braking torque command value τ ^ input as the signal 31 from the vehicle controller 9 are allowed. Judgment is made within the error range. The cause for determining that the regenerative torque command value τd and the braking torque command value τ ^ are different from each other beyond the error range may be, for example, an abnormality in the signal communication process. In this case, step S11 is denied. In step S12, it is determined that the brake command is abnormal.

Next, in step S13, it is determined whether the braking torque command value τ ^ and the estimated torque value τ ₀ are within an allowable error range. If the braking torque command value tau ^ and torque estimate tau ₀ is determined to be different than the error range, in step S14, the command based motor torque control amount of the inverter control unit 10, i.e. the motor torque command It is determined whether or not the value τ ^* and the estimated torque value τ ₀ are within an allowable error range.

If both determinations in steps S13 and S14 are No, the motor controller 14 corrects the torque constant φa in step S15. That is, the process of steps S3 to S9 in FIG. 4 described above is executed by the motor controller 14 to obtain the torque constant φa, which is stored in the motor controller 14 as a correction amount.

If it is determined in step S14 that the motor torque command value τ ^* based on the command of the inverter control unit 10 matches the torque estimate value τ ₀ of the regenerative braking torque estimated from the equation (3), the process proceeds to step S16. move on. That is, the step S14 is affirmative determination in step S13, in a situation where the braking torque command value tau ^ and torque estimate tau ₀ are different beyond the error range, braking the motor 1 from the vehicle controller 9 This is a case where the motor is not driven according to the torque command value τ ^. This means that the battery cannot accept regenerative power due to the abnormality of the battery 12. This situation is determined in step S16, and the regeneration by the motor 1 is stopped in the next step S17. That is, the torque compensator 30 outputs the switching signal 34 in order to stop the regenerative braking by the motor and switch to the braking by the electronically controlled friction brake. By this switching signal 34, the negative pressure-less brake 7 is driven so as to perform braking only by the friction brake when the brake pedal 6 is depressed.

When the braking torque command value τ ^ in step S13 described above and the estimated torque value τ ₀ of the regenerative braking torque estimated from the expression (3) are substantially the same, the motor controller 14 obtains the value in the processing shown in FIG. This is a case where the correction of the obtained torque constant is effective. In step S18, it is determined whether the deceleration acceleration of the vehicle is appropriate. If No, it is determined that the electronic friction brake may be abnormal. In step S19, a flag indicating that the friction brake may be abnormal is set. If Yes in step S18, it is determined in step S20 that everything is normal, and then, for example, the process returns to step S13 and the abnormality determination operation is continued until the vehicle stops. According to the embodiment of FIG. 5, it becomes possible to determine a plurality of abnormal factors during braking, and the safety of the electric vehicle can be improved.

In the electric vehicle to which the braking control device for the electric vehicle according to the second embodiment described above is applied, a permanent magnet motor is used, and the inverter control unit 10 controls the torque of the motor 1 by vector control. In the vector control, the three-phase current is converted into two types of control, i.e., an id component (current component in the same direction as the magnetic flux) and an iq component (component orthogonal to id) based on the concept of the rotating coordinate system. The motor torque is obtained by adding the second value determined by the product of the id component and the iq component to the first value determined by the product of the torque constant φ, the iq component and the number of poles. Here, as the second value is smaller, the aforementioned correction amount of the torque correction amount can be obtained with higher accuracy. Therefore, when the inverter control unit 10 decelerates to less than a predetermined number of rotations N ^* during braking, the current component id in the same direction as the magnetic flux is included in the current command value for vector control of the torque of the motor 1. while reducing below a predetermined value, and while reducing the electric current component id, conduct current detection I _B by the voltage detection V _DC and third current detecting unit 19 by the voltage detection unit, the motor 1 is regenerated To estimate the torque to be applied.

Further, not only the torque error of the motor 1 but also the battery 12 may detect its own state and determine that it is difficult to accept charging power. In this case, since the braking force cannot be obtained with the regenerative torque, it is necessary to obtain the necessary braking force by the friction brake, and the vehicle controller 9 distributes the braking request value according to the depression of the brake to the regenerative braking torque and the friction torque. On the other hand, it is necessary to instruct switching to obtain a braking force only by the friction brake. Therefore, the inverter control unit 10 calculates the torque control amount τ ^* of the motor 1 calculated by the equation (9) from the three-phase AC current values iu, iv, iw of the motor 1 detected by the current detection unit 16 and the vehicle controller 9. Then, the braking torque command value τ ^ instructed to the inverter control unit 10 is compared with the estimated torque value τ ₀ estimated by the equation (7) to determine whether the regenerative power can be accepted.

The determination as to whether or not the battery 12 is difficult to accept the charging power is performed as follows. Although the estimated torque value τ ₀ estimated by the torque estimating unit and the torque control amount τ ^* are substantially equal, the braking torque command value τ ^ instructed from the vehicle controller 9 to the inverter control unit 10 is different from these two. is there. This is a case where step S13 in FIG. 5 is denied and step S14 is affirmed, and is a phenomenon caused by a situation where the battery 12 itself cannot accept regenerative power. According to the second embodiment, in step S16, it is determined that such a phenomenon is a situation in which the battery 12 has difficulty in receiving charging power. In step S17, the regenerative braking by the motor 1 is changed to the electronically controlled friction brake. Switch to braking with.
By such control, even when it is difficult to receive regenerative power by the battery 12, it is possible to reliably generate a braking torque corresponding to depression of the brake pedal.
Moreover, since the motor controller 14 corrects the torque constant φa as appropriate, the accuracy of the switching timing from regenerative braking to friction braking is also improved.

Although the embodiment described above refers to the braking device for an electric vehicle, it can be applied to a hybrid vehicle and other systems, and is not limited to the configuration of the above embodiment. .

The present invention is not limited to the above-described embodiment, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention as long as the characteristics of the present invention are not impaired. It is.

DESCRIPTION OF SYMBOLS 1 Motor 6 Brake pedal 9 Vehicle controller 10 Inverter control part 11 Main circuit 12 Battery 13 Capacitor 14 Motor control controller 15 Magnetic pole position detector 16 1st electric current detector 17 2nd electric current detector 18 State monitoring apparatus 19 3rd Current detector 30 Torque compensator 57 Power calculator 58 Copper loss calculator 59 Angular velocity calculator 60 Torque calculator 61 Comparator 62 Accelerator pedal

Claims

An inverter control unit for controlling power supplied from the battery;
A motor that is controlled by the inverter control unit and applies driving torque to the driving wheel during power running operation, and applies regenerative braking torque to the driving wheel during regenerative operation;
A braking control unit that controls the sharing of the regenerative braking torque obtained by the regenerative electric power regenerated from the motor to the battery at the time of braking, and the friction braking torque by the electronically controlled friction brake;
The inverter control unit further includes:
A torque estimator for estimating the actual torque of the motor from regenerative power regenerated to the battery;
A feedback control unit that feedback-controls the regenerative braking torque output by the motor from a difference between a regenerative braking torque command value instructed to the motor by the braking control unit and an actual torque value estimated by the torque estimation unit; A braking control device for an electric vehicle.
The braking control device for an electric vehicle according to claim 1,
The torque estimating unit obtains a copper loss of the motor from a current detection value of a first current detector provided on a three-phase output line of the motor, and obtains the obtained copper loss, the angular velocity of the motor, and the regeneration. A braking control device for an electric vehicle that estimates an actual torque of the motor based on electric power.
In the braking control device for an electric vehicle according to claim 1 or 2,
The said torque estimation part is a braking control apparatus of the electric vehicle which calculates the said regenerative electric power based on the voltage between the positive / negative electrodes of the said battery, and the electric current regenerated to the said battery.
The braking control device for an electric vehicle according to claim 1,
The braking control device further includes a voltage detection unit that detects a voltage between the positive and negative terminals of the battery, and a third current detection unit that detects a current to be regenerated to the battery,
The torque estimation unit estimates an estimated value of torque regenerated by the motor based on the voltage value detected by the voltage detection unit during braking and the current detected by the third current detection unit,
The inverter control unit calculates and stores a correction amount for correcting torque based on the braking torque command value instructed to the motor by the braking control unit and the estimated torque value estimated by the torque estimation unit. The braking control apparatus of the electric vehicle which further has a quantity calculating part.
The braking control device for an electric vehicle according to claim 4,
The torque estimating unit reduces a current component in the same direction as the magnetic flux within a predetermined value within a current command value for vector control of the torque of the motor when the rotational speed of the motor is reduced below a predetermined rotational speed during braking. And a braking control device for an electric vehicle that performs voltage detection by the voltage detection unit and current detection by the third current detection unit in a state where the current component is reduced, and estimates a torque regenerated by the motor .
The braking control device for an electric vehicle according to claim 4 or 5,
The inverter control unit has a fourth current detection unit that detects a current supplied to the motor, calculates a torque control amount of the motor from a current value detected by the fourth current detection unit,
The braking control apparatus further compares the braking torque command value instructed to the motor, the estimated torque value estimated by the torque estimating unit, and the calculated torque control amount, and based on the three types of comparison results. ,
(1) the correction amount update process, (2) the battery accepts regenerative power, and (3) regenerative braking by the motor when it is determined that regenerative power cannot be accepted. A braking control device for an electric vehicle including a torque compensator that performs switching processing for switching to braking by a friction brake.