JP6648655B2 - Vehicle braking control device - Google Patents

Description

  The present invention relates to a vehicle braking control device.

  Patent Literature 1 discloses that "the target brake hydraulic pressure calculating means M1 is provided to the slave cylinder without increasing the size of the electric motor for driving the electric braking force generating means and increasing the response of the braking force generation." The target brake fluid pressure to be generated is calculated, the differentiating means M2 differentiates the target brake fluid pressure with time to calculate the rate of change of the target brake fluid pressure, and the field current calculating means M3 calculates the rate of change of the target brake fluid pressure. The electric motor control means M4 weakens the electric motor based on the field current command value based on the calculated field current command value of the electric motor that drives the slave cylinder based on the target brake fluid pressure. Is an emergency when it is necessary to rapidly increase the braking force. At this time, the field current command value is increased to increase the amount of field weakening of the electric motor, thereby increasing the rotation speed of the electric motor. Increased quickly to actuate the slave cylinder, it is possible to enhance the response of braking force generation "that have been described.

  Patent Literature 2 discloses that a motor drive cylinder 13 that applies brake fluid pressure to a wheel cylinder is operated by a brake operation in order to “increase the responsiveness of a brake force generated by an electric actuator with a simple configuration and further increase the response”. When the deviation Δθ between the target motor angle θt and the actual motor angle θm obtained in accordance with the amount is large, the drive control is performed by performing the field weakening control, for example, when the motor angle (rotation amount) is used as the operation amount of the electric actuator. Is capable of performing high-precision detection with a known simple and inexpensive rotation sensor, etc., widening the range of motor angle fluctuation, easily improving braking responsiveness, and being affected by fluctuations in load rigidity. In the transient state immediately after the start of the field weakening control, a deviation of the motor angle has occurred, and the field weakening control can be continuously performed. Variations in the response characteristic of the motor is reduced, it is described that stable response characteristics can be obtained. "

  Patent Documents 1 and 2 disclose "field weakening control (also referred to as flux weakening control)" by passing a negative current through the d-axis of an electric motor. In order for the flux-weakening control to be performed more effectively, control based on the state variables of the electric motor is required.

JP 2008-184057 A JP 2012-131293 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a brake control apparatus for a vehicle using a three-phase brushless motor, in which magnetic flux weakening control can be performed more effectively.

A vehicle braking control device according to the present invention drives an electric motor (MTR) based on a target pressing force (Fpt) according to a required braking force on a wheel (WH) of a vehicle, and is fixed to the wheel (WH). The friction member (MS) is pressed against the rotating member (KT) to generate a braking force on the wheel (WH). Brake control apparatus for a vehicle includes a driving circuit for driving the electric motor (MTR) (DRV), and the controller (ECU) for the controlling the drive circuit (DRV) on the basis of the target pressing force (Fpt), the electric The electric motor (MTR) includes a rotation angle sensor (MKA) for detecting a rotation angle (Mka) and a current sensor (IMA) for detecting an actual current (Ima) of the electric motor (MTR) .

In the vehicle braking control device according to the present invention, the controller (ECU) is configured to control the d-q axis current and the d- axis current of the electric motor (MTR) based on the specifications of the drive circuit (DRV). set the current characteristics in definitive current limit circle (Cis), in the dq-axis current characteristics, included in the current limit circle voltage limit circle (Cis) is calculated on the basis of the rotation angle (Mka) (Cvs) In this case, the intersection (0, iqm) between the q axis of the dq axis current characteristic and the current limiting circle (Cis) is calculated as the d axis and q axis target currents (Idt, Iqt), and the actual current is calculated. Based on (Ima), d-axis and q-axis actual currents (Ida, Iqa) are calculated, and the d-axis and q-axis actual currents (Ida, Iqa) are calculated as the d-axis and q-axis target currents (Idt, Iqt). The driving circuit is controlled so as to match ()) .

When the rotation speed of the electric motor is low and the current limiting circle Cis is included in the voltage limiting circle Cvs, the energizable area matches the current limiting circle Cis. In this case, the d-axis target current Idt is set to “0” based on the point (0, iqm) where the q-axis current Iqt is maximum in the current limiting circle Cis, and the q-axis target current Iqt is calculated. Although there is a trade-off relationship between the dq-axis currents, according to the above configuration, the electric motor MTR can output a sufficient torque.

In the braking control device for a vehicle according to the present invention, the controller (ECU) is configured to control the dq-axis current of the d-axis current and the q-axis current of the electric motor (MTR) based on the specifications of the drive circuit (DRV). A current limiting circle (Cis) in the characteristic is set, and in the dq-axis current characteristic, a voltage limiting circle (Cvs) calculated based on the rotation angle (Mka) is included in the current limiting circle (Cis). Represents the intersection (point R) of a straight line (Lcm) passing through the center (Pcm) of the voltage-limiting circle (Cvs) and parallel to the q-axis of the dq-axis current characteristic and the voltage-limiting circle (Cvs) on the d-axis; The d-axis and q-axis actual currents (Ida, Iqt) are calculated based on the actual current (Ima), and the d-axis and q-axis actual currents (Ida, Iqa) are calculated. , Iqa) are the d-axis and q-axis target powers. (Idt, Iqt) controls the drive circuit (DRV) to match.

When the rotation speed of the electric motor is very high and the voltage limiting circle Cvs is included in the current limiting circle Cis, a straight line Lcm passing through the center Pcm of the voltage limiting circle Cvs and parallel to the q axis (referred to as “q axis parallel line”) ) And the voltage limiting circle Cvs is the point of maximum output. According to the above configuration, since the intersection R between the q-axis parallel line Lcm and the voltage limiting circle Cvs is determined as the target current vector Imt (Idt, Iqt), the electric motor MTR can be efficiently driven.

1 is an overall configuration diagram of a vehicle equipped with a vehicle braking control device BCS according to the present invention. FIG. 3 is a functional block diagram for explaining processing in a controller ECU. FIG. 3 is a functional block diagram for explaining processing in a switching control block SWT. FIG. 3 is a circuit diagram for explaining a three-phase brushless motor MTR and a drive circuit DRV. FIG. 5 is a flowchart for explaining a first processing example in a target current calculation block IMT. FIG. 9 is a characteristic diagram for describing a first processing example in a target current calculation block IMT. FIG. 9 is a flowchart for explaining a second processing example in the target current calculation block IMT. FIG. 9 is a characteristic diagram for describing a second processing example in the target current calculation block IMT.

<Overall Configuration of Vehicle Braking Control Device According to the Present Invention>
The brake control device BCS according to the present invention will be described with reference to the overall configuration diagram of FIG. In the following description, constituent members, arithmetic processing, signals, characteristics, and values to which the same symbols are attached have the same function. Therefore, duplicate description may be omitted.

  The vehicle provided with the brake control device BCS includes a brake operation member BP, a brake operation amount sensor BPA, a controller ECU, a master cylinder MC, a stroke simulator SSM, a simulator shutoff valve VSM, a pressurizing unit KAU, a switching valve VKR, and a master cylinder pipe HMC. , A wheel cylinder pipe HWC and a pressure cylinder pipe HKC. Further, each wheel WH of the vehicle is provided with a brake caliper CP, a wheel cylinder WC, a rotating member KT, and a friction member MS.

  The braking operation member (for example, a brake pedal) BP is a member that the driver operates to decelerate the vehicle. By operating the braking operation member BP, the braking torque of the wheel WH is adjusted, and a braking force is generated on the wheel WH. Specifically, a rotating member (for example, a brake disk) KT is fixed to the wheels WH of the vehicle. Brake caliper CP is arranged so as to sandwich rotating member KT. A wheel cylinder WC is provided on the brake caliper (simply called a caliper) CP. By adjusting (increasing or decreasing) the hydraulic pressure in the wheel cylinder WC of the caliper CP, the piston in the wheel cylinder WC is moved (forward or backward) with respect to the rotating member KT. By this movement of the piston, a friction member (for example, a brake pad) MS is pressed against the rotating member KT, and a pressing force is generated. The rotating member KT and the wheel WH are fixed via a fixed shaft DS. Therefore, a braking torque (braking force) is generated on the wheel WH by the frictional force generated by the pressing force. Therefore, the braking force (requested braking force) required for the wheel WH is achieved according to the target value of the pressing force.

  The brake operation amount sensor (also simply referred to as an operation amount sensor) BPA is provided on the brake operation member BP. The operation amount Bpa of the braking operation member BP by the driver is detected by the operation amount sensor BPA. Specifically, as the operation amount sensor BPA, a hydraulic pressure sensor that detects the pressure of the master cylinder MC, an operation displacement sensor that detects the operation displacement of the brake operation member BP, and an operation that detects the operation force of the brake operation member BP At least one of the force sensors is employed. That is, the operation amount sensor BPA is a general term for the master cylinder hydraulic pressure sensor, the operation displacement sensor, and the operation force sensor. Therefore, the brake operation amount Bpa is determined based on at least one of the hydraulic pressure of the master cylinder MC, the operation displacement of the brake operation member BP, and the operation force of the brake operation member BP. The operation amount Bpa is input to the controller ECU.

  The controller (electronic control unit) ECU includes an electric circuit board on which a microprocessor and the like are mounted, and a control algorithm programmed in the microprocessor. The controller ECU controls the pressurizing unit KAU, the shutoff valve VSM, and the switching valve VKR based on the braking operation amount Bpa. Specifically, a signal (such as Sux) for controlling the electric motor MTR, the shutoff valve VSM, and the switching valve VKR is calculated based on a programmed control algorithm, and is output from the controller ECU.

  The controller ECU outputs a drive signal Vsm for opening the shut-off valve VSM when the operation amount Bpa becomes equal to or more than the predetermined value bp0, and the switching valve VKR connects the pressurized cylinder pipe HKC and the wheel cylinder pipe HWC. A drive signal Vkr for setting the communication state is output to each of the solenoid valves VSM and VKR. In this case, the master cylinder MC is in communication with the simulator SSM, and the pressurizing cylinder KCL is in communication with the wheel cylinder WC.

  The controller ECU calculates a drive signal (Sux or the like) for driving the electric motor MTR based on the operation amount Bpa, the rotation angle Mka, and the pressing force Fpa (for example, the hydraulic pressure of the pressurizing cylinder KCL), Output to the drive circuit DRV. Here, the braking operation amount Bpa is detected by a braking operation amount sensor BPA, the actual rotation angle Mka is detected by a rotation angle sensor MKA, and the actual pressing force Fpa is detected by a pressing force sensor FPA. The pressure of the brake fluid in the wheel cylinder WC is controlled (maintained, increased, or decreased) by the pressurizing unit KAU driven by the electric motor MTR.

  The master cylinder MC is mechanically connected to the brake operation member BP via a brake rod BRD. By the master cylinder MC, the operation force (brake pedal depression force) of the brake operation member BP is converted into the pressure of the brake fluid. The master cylinder MC is connected to a master cylinder pipe HMC, and when the braking operation member BP is operated, the brake fluid is discharged (pumped) from the master cylinder MC to the master cylinder pipe HMC. The master cylinder pipe HMC is a fluid path connecting the master cylinder MC and the switching valve VKR.

  A stroke simulator (also simply referred to as a simulator) SSM is provided to generate an operating force on the braking operation member BP. A simulator shutoff valve (simply called a shutoff valve) VSM is provided between the hydraulic chamber in the master cylinder MC and the simulator SSM. The shutoff valve VSM is a two-position solenoid valve having an open position and a closed position. When the shut-off valve VSM is in the open position, the master cylinder MC and the simulator SSM are in a communication state. When the shut-off valve VSM is in the closed position, the master cylinder MC and the simulator SSM are in a shut-off state (non-communication state). ). The shut-off valve VSM is controlled by a drive signal Vsm from the controller ECU. As the shutoff valve VSM, a normally closed solenoid valve (NC valve) may be employed.

  A piston and an elastic body (for example, a compression spring) are provided inside the simulator SSM. The brake fluid is moved from the master cylinder MC to the simulator SSM, and the piston is pushed by the flowing brake fluid. A force is applied to the piston in a direction in which the brake fluid is prevented from flowing into the piston. An operating force (for example, a brake pedal pressing force) when the braking operation member BP is operated is formed by the elastic body.

≪Pressure unit KAU≫
The pressurizing unit KAU uses the electric motor MTR as a power source to discharge (pressurize) the brake fluid to the pressurizing cylinder pipe HKC. Then, by this pressure, the pressurizing unit KAU presses (presses) the friction member MS against the rotating member KT, and applies a braking torque (braking force) to the wheel WH. In other words, the pressing unit KAU generates a force (pressing force) for pressing the friction member MS against the rotating member KT by the electric motor MTR.

  The pressure unit KAU includes an electric motor MTR, a drive circuit DRV, a power transmission mechanism DDK, a pressure shaft KSF, a pressure cylinder KCL, a pressure piston PKC, and a pressure sensor FPA.

  The electric motor MTR is a power source for the pressurizing cylinder KCL to adjust (pressurize, decompress, etc.) the pressure of the brake fluid in the wheel cylinder WC. As the electric motor MTR, a three-phase brushless motor is employed. The electric motor MTR has three coils CLU, CLV, CLW corresponding to the U-phase, V-phase, and W-phase, respectively, and is driven by the drive circuit DRV. The electric motor MTR is provided with a rotation angle sensor MKA for detecting a rotor position (rotation angle) Mka of the electric motor MTR. The rotation angle Mka is input to the controller ECU.

  The drive circuit DRV is an electric circuit board on which a switching element (power semiconductor device) for driving the electric motor MTR and the like are mounted. Specifically, a three-phase bridge circuit is formed in the drive circuit DRV, and the energization state of the electric motor MTR is controlled based on a drive signal (Sux or the like). The drive circuit DRV is provided with a current sensor (for example, a current sensor) IMA for detecting an actual current Ima (a generic name of each phase) to the electric motor MTR. The current (detected value) Ima of each phase is input to the controller ECU.

  The power transmission mechanism DDK reduces the rotational power of the electric motor MTR, converts the rotational power into linear power, and outputs the linear power to the pressurizing shaft KSF. Specifically, the power transmission mechanism DDK is provided with a speed reducer (not shown), and the rotational power from the electric motor MTR is reduced and output to a screw member (not shown). Then, the rotational power is converted into the linear power of the pressurizing shaft KSF by the screw member. That is, the power transmission mechanism DDK is a rotation / linear motion conversion mechanism.

  A pressure piston PKC is fixed to the pressure shaft KSF. The pressurizing piston PKC is inserted into an inner hole of the pressurizing cylinder KCL, and a combination of the piston and the cylinder is formed. Specifically, a seal member (not shown) is provided on the outer periphery of the pressurizing piston PKC to ensure liquid tightness with the inner hole (inner wall) of the pressurizing cylinder KCL. That is, a pressurizing chamber Rkc which is partitioned by the pressurizing cylinder KCL and the pressurizing piston PKC and is filled with the brake fluid is formed.

  The volume of the pressure chamber Rkc is changed by moving the pressure piston PKC in the direction of the central axis in the pressure cylinder KCL. Due to this volume change, the brake fluid is moved between the pressurizing cylinder KCL and the wheel cylinder WC via the brake pipes (fluid passages) HKC and HWC. The hydraulic pressure in the wheel cylinder WC is adjusted by the inflow and outflow of the brake fluid from the pressurizing cylinder KCL, and as a result, the force (pressing force) of the friction member MS pressing the rotating member KT is adjusted.

  For example, a hydraulic pressure sensor for detecting the hydraulic pressure Fpa of the pressurizing chamber Rkc is built in the pressurizing unit KAU (particularly, the pressurizing cylinder KCL) as the pressing force sensor FPA. The fluid pressure sensor (corresponding to a pressing force sensor) FPA is fixed to the pressurizing cylinder KCL, and is integrally formed as a pressurizing unit KAU. The detection value Fpa of the pressing force (that is, the hydraulic pressure of the pressurizing chamber Rkc) is input to the controller ECU. The pressurizing unit KAU has been described above.

  The switching valve VKR switches between a state where the wheel cylinder WC is connected to the master cylinder MC and a state where the wheel cylinder WC is connected to the pressurizing cylinder KCL. The switching valve VKR is controlled based on a drive signal Vkr from the controller ECU. Specifically, when the braking operation is not performed (in the case of “Bpa <bp0”), the wheel cylinder pipe HWC is brought into communication with the master cylinder pipe HMC via the switching valve VKR, and pressurized. The cylinder pipe HKC is not communicated (cut off). Here, the wheel cylinder piping HWC is a fluid path connected to the wheel cylinder WC. When the braking operation is performed (that is, when the state of “Bpa ≧ bp0” is reached), the switching valve VKR is excited based on the drive signal Vkr, and the communication between the wheel cylinder pipe HWC and the master cylinder pipe HMC is cut off. The cylinder pipe HWC and the pressurized cylinder pipe HKC are brought into communication.

<Process in controller ECU>
With reference to the functional block diagram of FIG. 2, the processing in the controller (electronic control unit) ECU will be described. Note that, as described above, the constituent members, arithmetic processing, signals, characteristics, and values having the same symbols exhibit the same function.

  The controller ECU drives the electric motor MTR and excites the solenoid valves VSM and VKR based on the operation amount Bpa of the braking operation member BP. A drive circuit DRV (three-phase bridge circuit) is formed by the switching elements SUX, SUZ, SVX, SVZ, SWX, and SWZ (also simply referred to as “SUX to SWZ”). The drive of the electric motor MTR is executed by the drive circuit DRV. Specifically, signals Sux, Suz, Svx, Svz, Swx, and Swz (also simply referred to as “Sux to Swz”) for driving switching elements SUX to SWZ are calculated by controller ECU. Further, signals Vsm and Vkr for driving solenoid valves VSM and VKR are determined by controller ECU.

  The controller ECU includes a command pressing force calculation block FPS, a wheel slip control block FSC, a command current calculation block IMS, a pressing force feedback control block FFB, a target current calculation block IMT, a switching control block SWT, and a solenoid valve control block SLC. Be composed.

  In the command pressing force calculation block FPS, the command pressing force Fps is calculated based on the braking operation amount Bpa and the calculation characteristic (calculation map) CFps. Here, the instruction pressing force Fps is a target value of the hydraulic pressure (corresponding to the pressing force) generated by the pressurizing unit KAU. Specifically, in the calculation characteristic CFps, the command pressing force Fps is calculated to be “0 (zero)” in a range from the braking operation amount Bpa of zero (corresponding to the case where the braking operation is not performed) to less than the predetermined value bp0. When the operation amount Bpa is equal to or more than the predetermined value bp0, the calculation is performed such that the instruction pressing force Fps monotonically increases from “0” as the operation amount Bpa increases. Here, the predetermined value bp0 is a value corresponding to “play” of the braking operation member BP.

  In the wheel slip control block FSC, an adjustment pressing force Fsc, which is a target value for wheel slip control, is calculated. Here, the "wheel slip control" is to control the slip state of the four wheels WH of the vehicle independently and separately to improve the stability of the vehicle. That is, the wheel slip control is at least one of anti-skid control (Antilock Brake Control), traction control (Traction Control), and vehicle stabilization control (Electronic Stability Control). Therefore, in the wheel slip control block FSC, the adjustment pressing force Fsc for executing at least one of the anti-skid control, the traction control, and the vehicle stabilization control is calculated.

  In the wheel slip control block FSC, an adjustment pressing force Fsc for anti-skid control is calculated. Specifically, based on the acquisition result (wheel speed Vwa) of the wheel speed sensor VWA provided for each wheel WH, an adjustment pressing force Fsc for executing anti-skid control to prevent wheel lock is calculated. For example, based on the wheel speed Vwa, a wheel slip state amount Slp (a control variable indicating the state of the wheel deceleration slip) is calculated. Then, the adjustment pressing force Fsc is determined based on the wheel slip state amount Slp.

  Similarly, in the wheel slip control block FSC, an adjustment pressing force Fsc is calculated based on the acquisition result (wheel speed Vwa) of the wheel speed sensor VWA to execute traction control to suppress wheel spin (overspeed). You. Specifically, the adjustment pressing force Fsc is determined based on the wheel slip state amount Slp (a control variable representing the state of the wheel acceleration slip).

  Further, in the wheel slip control block FSC, based on the acquisition results (steering angle Saa, yaw rate Yra, lateral acceleration Gya) of the steering angle sensor SAA and the vehicle behavior sensors (yaw rate sensor YRA, lateral acceleration sensor GYA), An adjustment pressing force Fsc for executing the vehicle stabilization control so as to maintain stability is calculated. Specifically, based on the steering angle Saa, the yaw rate Yra, the lateral acceleration Gya, and the vehicle speed Vxa, the adjustment pressing force Fsc is determined so as to suppress at least one of excessive understeer and oversteer of the vehicle. Is done.

  The instruction pressing force Fps from the instruction pressing force calculation block FPS and the adjustment pressing force Fsc from the wheel slip control block FSC are adjusted by adjustment calculation (addition calculation), and the target pressing force Fpt is calculated. Here, the target pressing force Fpt is a final target value of the pressing force, and corresponds to the required braking force for the wheel WH. Specifically, the target pressing force Fpt is determined by adding the adjustment pressing force Fsc from the instruction pressing force Fps. For example, when the anti-skid control is executed in the wheel slip control block FSC, an adjustment pressing force Fsc (negative value) for reducing and adjusting the instruction pressing force Fps is calculated so as to avoid wheel lock. You. Further, when the vehicle stabilization control for suppressing oversteer is executed in the wheel slip control block FSC, the command pressing force Fps is adjusted so as to increase the pressing force corresponding to the turning front wheel of the vehicle. The adjustment pressing force Fsc (positive value) to be adjusted is determined.

  In the command current calculation block IMS, the command current Ims of the electric motor MTR is calculated based on the target pressing force Fpt and a preset calculation characteristic (calculation map) CIms. Here, the command current Ims is a target value of a current for controlling the electric motor MTR. In the calculation characteristic CIms, the command current Ims is determined such that the command current Ims monotonically increases from "0" as the target pressing force Fpt increases from "0".

  In the pressing force feedback control block FFB, the target value of the pressing force (for example, target hydraulic pressure) Fpt and the actual value of the pressing force (hydraulic pressure detection value) Fpa are used as control state variables, and based on these, the electric motor is controlled. An MTR compensation current Ifp is calculated. An error occurs in the pressing force only by the control based on the instruction current Ims. Therefore, the pressing force feedback control block FFB compensates for the error. The pressing force feedback control block FFB includes a comparison calculation and a compensation current calculation block IFP.

  By the comparison calculation, the target value Fpt of the pressing force (corresponding to the required braking force of the wheel WH) is compared with the actual value Fpa (corresponding to the actually generated braking force). Here, the actual value Fpa of the pressing force is a detection value detected by the pressing force sensor FPA (for example, a hydraulic pressure sensor that detects the hydraulic pressure of the pressurizing cylinder KCL). In the comparison calculation, a deviation (pressing force deviation) eFp between the target pressing force (target value) Fpt and the actual pressing force (detected value) Fpa is calculated. The pressing force deviation eFp is input to the compensation current calculation block IFP as a control variable.

  The compensation current calculation block IFP includes a proportional element block, a differential element block, and an integral element block. In the proportional element block, the pressing force deviation eFp is multiplied by the proportional gain Kp to calculate a proportional element of the pressing force deviation eFp. In the differential element block, the pressing force deviation eFp is differentiated, multiplied by a differential gain Kd, and the differential element of the pressing force deviation eFp is calculated. In the integral element block, the pressing force deviation eFp is integrated, and the integral is multiplied by the integral gain Ki to calculate the integral element of the pressing force deviation eFp. Then, the compensation element Ifp is calculated by adding the proportional element, the differential element, and the integral element. That is, in the compensation current calculation block IFP, the actual pressing force (detected value) Fpa is changed to the target pressing force (target value) Fpt based on the comparison result (pressing force deviation eFp) between the commanded pressing force Fps and the actual pressing force Fpa. A so-called PID control based on the pressing force is executed so that they match (that is, the deviation eFp approaches “0 (zero)”).

  In the target current calculation block IMT, a target current (target current vector) Imt, which is a final target value of the current, based on the command current Ims, the compensation current (compensation value by the pressing force feedback control) Ifp, and the rotation angle Mka. Is calculated. The target current Imt is a vector on the dq axes, and is formed by a d-axis component (also called “d-axis target current”) Idt and a q-axis component (also called “q-axis target current”) Iqt. The target current Imt is also described as a target current vector (Idt, Iqt). The method of calculating the target current Imt will be described later.

  In the target current calculation block IMT, the sign (positive or negative value) of the target current Imt is determined based on the direction in which the electric motor MTR should rotate (that is, the direction in which the pressing force increases or decreases). Further, the magnitude of the target current Imt is calculated based on the rotational power to be output by the electric motor MTR (that is, the amount of increase or decrease in the pressing force). Specifically, when increasing the braking pressure, the sign of the target current Imt is calculated to be a positive sign (Imt> 0), and the electric motor MTR is driven in the normal rotation direction. On the other hand, when decreasing the braking pressure, the sign of the target current Imt is determined to be a negative sign (Imt <0), and the electric motor MTR is driven in the reverse direction. Further, the output torque (rotational power) of the electric motor MTR is controlled to increase as the absolute value of the target current Imt increases, and the output torque is controlled to decrease as the absolute value of the target current Imt decreases.

  In the switching control block SWT, drive signals Sux to Swz for performing pulse width modulation on each of the switching elements SUX to SWZ are calculated based on the target current Imt (Idt, Iqt). Based on the target current Imt and the rotation angle Mka, a target value Emt of each of the U-phase, V-phase, and W-phase voltages (a general term for the target voltages Eut, Evt, and Ewt of each phase) is calculated. Based on the target voltage Emt of each phase, the duty ratio Dtt of the pulse width of each phase (a collective term for the duty ratios Dut, Dvt, and Dwt of each phase) is determined. Here, the “duty ratio” is a ratio of the ON time to one cycle, and “100%” corresponds to full energization. Then, based on the duty ratio (target value) Dtt, whether each of the switching elements SUX to SWZ forming the three-phase bridge circuit is turned on (energized state) or turned off (non-energized state) The drive signals Sux to Swz are calculated. The drive signals Sux to Swz are output to the drive circuit DRV.

  The energized or de-energized states of the six switching elements SUX to SWZ are individually controlled by the six drive signals Sux to Swz. Here, as the duty ratio Dtt (general term for each phase) is larger, the energizing time per unit time is longer in each switching element, and a larger current flows through the coil. Therefore, the rotational power of the electric motor MTR is increased.

  In the drive circuit DRV, a current sensor IMA (a general term for the current sensors IUA, IVA, and IWA for each phase) is provided for each phase, and an actual current Ima (a general term for the actual currents Iua, Iva, and Iwa for each phase) is detected. You. The detected value Ima (collectively) of each phase is input to the switching control block SWT. Then, so-called current feedback control is performed so that the detected value Ima of each phase matches the target value Imt. Specifically, in each phase, the duty ratio Dtt (a collective term for the duty ratios Dut, Dvt, and Dwt of each phase) is individually corrected (finely adjusted) based on the deviation between the actual current Ima and the target current Imt. You. With this current feedback control, highly accurate motor control can be achieved.

  In the solenoid valve control block SLC, drive signals Vsm and Vkr for controlling the solenoid valves VSM and VKR are calculated based on the operation amount Bpa. When the operation amount Bpa is less than the predetermined amount bp0 (particularly, when “Bpa = 0”), the drive signal Vsm is determined such that the simulator cutoff valve VSM is set to the open position in response to the non-braking operation ( For example, when the shutoff valve VSM is an NC valve, the drive signal Vsm indicates non-excitation). At the same time, in the case of “Bpa <bp0”, “a state where the master cylinder MC and the wheel cylinder WC are communicated and the pressurizing cylinder KCL and the wheel cylinder WC are cut off (referred to as a non-excited state)” The drive signal Vkr is calculated.

  The time after the operation amount Bpa is increased and the operation amount Bpa becomes equal to or more than the predetermined amount bp0 corresponds to the braking operation, and at this time (the braking operation start time), the shut-off valve VSM is changed from the closed position to the open position. Drive signal Vsm is determined. When the shutoff valve VSM is an NC valve, an excitation instruction is started as the drive signal Vsm at the start of the braking operation. At the time of the start of the braking operation, the drive signal Vkr is changed so that the master cylinder MC and the wheel cylinder WC are shut off and the pressurizing cylinder KCL and the wheel cylinder WC are communicated (referred to as an excited state). It is determined.

<Processing in switching control block SWT>
The processing in the switching control block SWT will be described with reference to the functional block diagram of FIG. In the switching control block SWT, drive signals Sux to Swz for the six switching elements SUX to SWZ forming the three-phase bridge circuit BRG are determined based on the target current Imt, the actual current Ima, and the rotation angle Mka. The switching control block SWT includes a first conversion operation block IHA, a target voltage operation block EDQ, a second conversion operation block EMT, a target duty operation block DTT, and a drive signal operation block SDR. The electric motor MTR is driven by so-called vector control.

  In the first conversion operation block IHA, the converted actual current Iha is calculated based on the actual current Ima and the rotation angle Mka. The converted actual current Iha is obtained by subjecting the actual current Ima to three-phase to two-phase conversion, and further converting the fixed coordinates to the rotating coordinates. The converted actual current Iha is a vector on the dq axes (rotor fixed coordinates), and includes a d-axis component (also referred to as “d-axis actual current”) Ida and a q-axis component (also referred to as “q-axis actual current”) Iqa. Formed.

  First, in the first conversion operation block IHA, the actual current Ima is subjected to three-phase to two-phase conversion. The actual current Ima is a general term for each phase (U-phase, V-phase, W-phase) of the bridge circuit BRG, and specifically, the U-phase actual current Iua, the V-phase actual current Iva, and the W-phase actual current Iwa It is composed of In order to handle three signals simultaneously, calculations in a three-dimensional space are required. In order to facilitate the calculation, the fact that “Iua + Iva + Iwa = 0” is satisfied in an ideal three-phase AC, and the three-phase real current Ima (Iua, Iva, Iwa) is changed to the two-phase real current Ina (Iα). , Iβ). The conversion from three phases to two phases is called "Clarke conversion or αβ conversion".

  The three-phase real currents (detected values) Iua, Iva, Iwa are converted into two-phase real currents Iα, Iβ by Clark conversion. That is, the real currents Iua, Iva, Iwa of the symmetric three-phase alternating current (three-phase alternating currents shifted by 120 degrees) are converted into the equivalent real currents Iα, Iβ of the two-phase alternating current.

  Further, in the first conversion calculation block IHA, coordinate conversion from fixed coordinates (stationary coordinates) to rotation coordinates is performed based on the rotation angle Mka, and a conversion actual current Iha is calculated. The converted actual current Iha is formed by a d-axis component (d-axis actual current) Ida and a q-axis component (q-axis actual current) Iqa. That is, since the current value Ina subjected to the Clark conversion is a current flowing through the rotor, the current value Ina is coordinate-converted to rotor fixed coordinates (rotational coordinates, dq axis coordinates). Here, the conversion from the fixed coordinates to the rotation coordinates is called “Park (Park) conversion”. Conversion from fixed coordinates to rotation coordinates (dq-axis coordinates) is performed based on the rotor rotation angle Mka from the rotation angle sensor MKA, and the actual current Iha (Ida, Iqa) after coordinate conversion is determined.

  In the target voltage calculation block EDQ, the target voltage vector Edq is calculated based on the target current vector Imt (Idt, Iqt) and the actual current Iha (Ida, Iqa) after the park conversion. In the vector control, so-called current feedback control is performed such that “d-axis and q-axis components Idt and Iqt of the target current” match “d-axis and q-axis components Ida and Iqa of the actual current”. Therefore, in the target voltage calculation block EDQ, PI control is performed based on the deviation (current deviation) between “d-axis, q-axis target currents Idt, Iqt” and “d-axis, q-axis actual currents Ida, Iqa”. Will be In PI control, P control (proportional control, which is controlled according to a deviation between a target value and an execution value, and control) and I control (integral control, which is controlled according to an integrated value of the deviation) ) Are performed in parallel.

  Specifically, in the target voltage calculation block EDQ, based on the deviation between the target current Imt and the converted actual current Iha, the current deviation decreases (ie, the deviation approaches “0”) and the target voltage Edq Is determined. The target voltage Edq is a vector on the dq axis, and includes a d-axis component (also referred to as “d-axis target voltage”) Edt and a q-axis component (also referred to as “q-axis target voltage”) Eqt.

  In the second conversion operation block EMT, the final target voltage Emt is calculated based on the target voltage vector Edq and the rotation angle Mka. The target voltage Emt is a general term for each phase of the bridge circuit BRG, and includes a U-phase target voltage Eut, a V-phase target voltage Evt, and a W-phase target voltage Ewt.

  First, in the second conversion operation block EMT, the target voltage vector Edq is inversely transformed from the rotation coordinates to the fixed coordinates based on the rotation angle Mka, and two-phase target voltages Eα and Eβ are calculated. This conversion is called an "inverse Park (park) conversion." Then, the two-phase target voltages Eα and Eβ are inversely converted into three-phase target voltages Emt (voltage target values Eut, Evt, and Ewt for each phase) by the space vector conversion.

  In the target duty calculation block DTT, the duty ratio (target value) Dtt of each phase is calculated based on the target voltage Emt of each phase. The duty ratio Dtt is a generic term for each phase, and includes a U-phase duty ratio Dut, a V-phase duty ratio Dvt, and a W-phase duty ratio Dwt. Specifically, the calculation is performed such that the duty ratio Dtt monotonically increases from "0" as the voltage target value Emt of each phase increases from "0" according to the calculation characteristic CDtt.

  In the drive signal calculation block SDR, signals Sux to Swz for driving the switching elements SUX to SWZ, which constitute each phase of the bridge circuit BRG, are determined based on the duty ratio Dtt. On / off of each switching element SUX-SWZ is switched based on each drive signal Sux-Swz, and the electric motor MTR is driven.

<Three-phase brushless motor MTR and drive circuit DRV>
The three-phase brushless motor MTR and its drive circuit DRV will be described with reference to the electric circuit diagram of FIG. The three-phase brushless motor MTR has three coils (windings) of a U-phase coil CLU, a V-phase coil CLV, and a W-phase coil CLW. In the brushless motor MTR, a magnet is arranged on a rotor (rotor) side, and a winding circuit (coil) is arranged on a stator (stator) side, and commutation is performed by a drive circuit at a timing corresponding to the magnetic pole of the rotor. , Is driven to rotate.

  The electric motor MTR is provided with a rotation angle sensor MKA that detects a rotation angle (rotor position) Mka of the electric motor MTR. A hall element type is used as the rotation angle sensor MKA. Further, a variable reluctance resolver may be employed as the rotation angle sensor MKA. The rotation angle Mka is input to the switching control block SWT of the controller ECU.

  The drive circuit DRV includes a three-phase bridge circuit (also simply referred to as a bridge circuit) BRG and a stabilizing circuit LPF. The drive circuit DRV is an electric circuit that drives the electric motor MTR, and is controlled by the switching control block SWT.

  The bridge circuit BRG is formed by six switching elements (power transistors) SUX, SUZ, SVX, SVZ, SWX, and SWZ (also referred to as “SUX to SWZ”). The bridge circuit BRG is driven based on the drive signals Sux, Suz, Svx, Svz, Swx, Swz (also referred to as “Sux to Swz”) of each phase from the switching control block SWT in the drive circuit DRV, and the electric motor MTR Output is adjusted.

  In the switching control block SWT, an instruction value (target value) for performing pulse width modulation for each switching element is calculated based on the target current Imt. The duty ratio (the ratio of the ON time to one cycle) of the pulse width is determined based on the magnitude of the target current Imt and a characteristic (operation map) set in advance. In addition, the rotation direction of the electric motor MTR is determined based on the sign (positive or negative) of the target current Imt. For example, the rotation direction of the electric motor MTR is set as a positive (plus) value in the forward rotation direction and as a negative (minus) value in the reverse rotation direction. Since the final output voltage is determined by the input voltage (voltage of the battery BAT) and the duty ratio Dtt, the rotation direction and the output torque of the electric motor MTR are determined.

  Further, in the switching control block SWT, each switching element included in the bridge circuit BRG is turned on (energized state) or turned off (non-energized state) based on the duty ratio (target value) Dtt. The drive signals Sux to Swz are calculated. The energized or de-energized states of the switching elements SUX to SWZ are controlled by these drive signals Sux to Swz. Specifically, as the duty ratio Dtt is larger, the energizing time per unit time is longer in the switching element, a larger current is supplied to the electric motor MTR, and the output (rotational power) is increased.

  The storage battery BAT is connected to the input side of the three-phase bridge circuit (also referred to as an inverter circuit) BRG via a stabilizing circuit LPF, and the electric motor MTR is connected to the output side of the bridge circuit BRG. In the bridge circuit BRG, three phases (U-phase, V-phase, and W-phase) are formed using a voltage-type bridge circuit having an upper and lower arm in which switching elements are connected in series as one phase. The upper arms of the three phases are connected to a power line PWL connected to the anode side of the storage battery BAT. The lower arms of the three phases are connected to a power line PWL connected to the cathode side of the storage battery BAT. In the bridge circuit BRG, the upper and lower arms of each phase are connected to the power line PWL in parallel with the storage battery BAT.

  The six switching elements SUX to SWZ are elements that can turn on or off a part of an electric circuit. For example, MOS-FETs and IGBTs are used as the switching elements SUX to SWZ. In the brushless motor MTR, the switching elements SUX to SWZ forming the bridge circuit BRG are controlled based on the detected value Mka of the rotation angle (rotor position). Then, the current directions (that is, excitation directions) of the coils CLU, CLV, CLW of each of the three phases (U phase, V phase, W phase) are sequentially switched, and the electric motor MTR is rotationally driven. That is, the rotation direction (forward rotation direction or reverse rotation direction) of the brushless motor MTR is determined by the relationship between the rotor and the position to be excited. Here, the forward rotation direction of the electric motor MTR is a rotation direction corresponding to an increase in the hydraulic pressure (resultingly, pressing force) Fpa by the pressurizing unit KAU, and the reverse rotation direction of the electric motor MTR is a decrease in the hydraulic pressure Fpa. Is the rotation direction corresponding to.

  A current sensor IMA (general term) for detecting an actual current Ima (general term for each phase) between the bridge circuit BRG and the electric motor MTR is provided for each of the three phases (U phase, V phase, W phase). Specifically, a U-phase current sensor IUA for detecting a U-phase actual current Iua, a V-phase current sensor IVA for detecting a V-phase actual current Iva, and a W-phase current sensor IWA for detecting a W-phase actual current Iwa are: Provided for each phase. The detected currents Iua, Iva, Iwa of each phase are respectively input to the switching control block SWT.

  Then, in the switching control block SWT, the above-described current feedback control is executed. The duty ratio Dtt is corrected (finely adjusted) based on the deviation between the actual current Ima and the target current Imt. By this current feedback control, control is performed so that the actual value Ima and the target value Imt match (that is, the current deviation approaches “0”). As a result, highly accurate motor control can be achieved.

  Drive circuit DRV is supplied with power from a power source (storage battery BAT, generator ALT). The drive circuit DRV is provided with a stabilization circuit LPF in order to reduce the fluctuation of the supplied power (voltage). The stabilization circuit LPF is configured by a combination of at least one capacitor (capacitor) and at least one inductor (coil), and is a so-called LC circuit.

<First processing example in target current calculation block IMT>
The first processing example in the target current calculation block IMT will be described with reference to the flowchart of FIG. 5 and the characteristic diagram of FIG. The first processing example corresponds to the case where the center Pcn (idc, 0) of the voltage limiting circle Cvs is located outside the current limiting circle Cis. First, the flow of processing when the electric motor MTR is driven in the normal rotation direction will be described with reference to the flowchart of FIG.

  In step S110, the command current Ims, the compensation current Ifp, the rotation angle Mka, and the current limiting circle Cis are read. Here, the current limiting circle Cis indicates the allowable current (conduction current) of the switching elements SUX to SWZ (a component of the drive circuit DRV) in the current characteristics (dq-axis plane) of the q-axis current and the d-axis current of the electric motor MTR. It is set in advance based on the obtained maximum current) iqm. That is, the current limiting circle Cis is determined from the specifications of the drive circuit DRV (particularly, the rated current values iqm of the switching elements SUX to SWZ). Here, the predetermined value iqm is referred to as “q-axis maximum current”.

  In step S120, a command current (compensation command current) Imr that is compensated based on the pressing force feedback control is calculated based on the command current Ims and the compensation current Ifp based on the pressing force feedback control. Specifically, compensation current Ifp is added to instruction current Ims, and compensation instruction current Imr is determined (Imr = Ims + Ifp).

  In step S130, the electric angular velocity ω of the electric motor MTR is calculated based on the detection value (rotation angle) Mka of the rotation angle sensor MKA. Specifically, the rotation angle (mechanical angle) Mka is converted into an electrical angle θ, and the electrical angle θ is time-differentiated to determine an electrical angular velocity ω. Here, the “mechanical angle Mka” corresponds to the rotation angle of the output shaft of the electric motor MTR. The “electric angle θ” is expressed as an angle with one period of the magnetic field in the electric motor MTR being 2π [rad]. Note that the electrical angle θ can be directly detected by the rotation angle sensor MKA.

  In step S140, a voltage limiting circle Cvs is calculated based on the electric angular velocity θ of the electric motor MTR. Specifically, in the dq-axis current characteristics (Idt-Iqt plane) of the electric motor MTR, the voltage limiting circle Cvs is expressed by “power supply voltage (that is, the voltage of the storage battery BAT and the voltage of the generator ALT) Eba, phase inductance (that is, the coil CLU, CLV, and CLW inductances) L and predetermined values in the number of interlinkage magnetic fluxes (that is, the strength of the magnets) φ, and “the electrical angular velocity ω of the electric motor MTR calculated from the rotation angle Mka”. Is calculated based on As the rotation speed dMk of the electric motor MTR increases, the radius of the voltage limiting circle Cvs decreases, and as the rotation speed dMk decreases, the radius of the voltage limiting circle Cvs increases.

  In step S150, based on the current limiting circle Cis and the voltage limiting circle Cvs, the points Pxa (Idx, Iqx), Pxb (Pxa) where the current limiting circle Cis and the voltage limiting circle Cvs intersect on the dq-axis current plane. Idx, -Iqx) are calculated. Here, the values Idx and Iqx (or -Iqx) are variables representing the coordinates of the intersections Pxa and Pxb on the dq axes. Further, the intersection Pxa (Idx, Iqx) corresponds to the forward rotation direction of the electric motor MTR, and the intersection Pxb (Idx, -Iqx) corresponds to the reverse rotation direction. The intersections Pxa and Pxb are also collectively referred to as “intersection Px”.

  The area where the current limiting circle Cis and the voltage limiting circle Cvs overlap is the range of the current that can actually be achieved by the current feedback control (referred to as the “energizable area”). Therefore, even if an instruction outside the energizable region is issued, this instruction cannot be actually achieved in the current feedback control. When the rotation speed dMk is low (for example, when the electric motor MTR is stopped), the intersection Px (a general term for Pxa and Pxb) may not exist.

  In step S160, "whether or not the intersection points Pxa (Idx, Iqx) and Pxb (Idx, -Iqx) exist in the first and fourth quadrants in the dq-axis current plane" or "Current limit circle" Whether or not Cis is included in the voltage limiting circle Cvs ”is determined. Here, the “first quadrant” is a region where both the d-axis current and the q-axis current have a positive sign. The “fourth quadrant” is a region where the d-axis current is positive and the q-axis current is negative. If the intersection Px (general term for Pxa and Pxb) exists in the first and fourth quadrants and step S160 is affirmed ("YES"), the process proceeds to step S180. On the other hand, if the intersection Px is in the second or third quadrant and step S160 is negative ("NO"), the process proceeds to step S170. If the current limiting circle Cis is included in the voltage limiting circle Cvs and there is no intersection Px, step S160 is affirmed and the process proceeds to step S180.

  In step S170, based on the compensation instruction current Imr and the coordinates (Idx, Iqx) of the intersection Pxa, “whether or not the compensation instruction current Imr is equal to or greater than the q-axis coordinate Iqx (variable) of the intersection Pxa”. Is determined. If “Imr ≧ Iqx” and step S170 is affirmative (“YES”), the process proceeds to step S210. On the other hand, if “Imr <Iqx” and step S170 is negative (“NO”), the process proceeds to step S215. Step S170 corresponds to the forward rotation drive of the electric motor MTR, and the compensation instruction current Imr is a value larger than “0”.

  In step S180, based on the compensation instruction current Imr and the current limiting circle Cis, it is determined whether “the compensation instruction current Imr is equal to or larger than the q-axis intersection iqm of the current limiting circle Cis”. If “Imr ≧ iqm” and step S180 is affirmative (“YES”), the process proceeds to step S230. On the other hand, if “Imr <iqm” and step S180 is negative (“NO”), the process proceeds to step S240.

  In step S210, the d-axis target current Idt is determined as the intersection d-axis coordinate Idx (variable), and the q-axis target current Iqt is determined as the intersection q-axis coordinate Iqx (variable). In step S215, based on the compensation instruction current Imr and the voltage limiting circle Cvs, a voltage limiting circle d-axis coordinate Ids (a variable, also simply referred to as a limiting circle d-axis coordinate) is calculated. Specifically, the limited circle d-axis coordinate Ids is a d-axis coordinate of a point where the voltage limited circle Cvs intersects with “Iqt = Imr”. That is, it is the value (coordinates) of the d-axis target current Idt when the compensation instruction current Imr is substituted for the q-axis target current Iqt on the voltage-limited circle Cvs (see equation (2) described later). Then, in step S220, it is determined that the d-axis target current Idt matches the voltage limiting circle d-axis coordinate Ids, and the q-axis target current Iqt matches the compensation instruction current Imr.

  In step S230, the d-axis target current Idt is determined to be “0”, and the q-axis target current Iqt is determined to be the q-axis maximum current iqm (predetermined value). In step S240, the d-axis target current Idt is determined to be “0”, and the q-axis target current Iqt is determined to be equal to the compensation instruction current Imr.

<< Relationship between the current limiting circle Cis and the voltage limiting circle Cvs in the first processing example >>
Next, processing in each step of the first processing example will be described with reference to the characteristic diagram of FIG. As described above, it is assumed that the electric motor MTR is driven in the normal rotation direction. Therefore, the compensation instruction current Imr is calculated as a positive value on the q axis. When the electric motor MTR is driven in the reverse direction, the compensation instruction current Imr is determined as a negative value on the q axis, and the target current Imt is determined based on the intersection Pxb instead of the intersection Pxa. Is done.

  The current limiting circle Cis is determined based on the maximum rated value (rated current iqm) of the switching element that forms the drive circuit DRV (particularly, the bridge circuit BRG). Here, the maximum rated value is determined as a maximum allowable value of a current that can flow through a switching element (such as a power MOS-FET), an applicable voltage, and a power loss.

Specifically, the current limiting circle Cis is expressed as a circle centered on the origin O (the point of “Idt = 0, Iqt = 0”) in the dq-axis current characteristics (Idt-Iqt plane). Further, the radius of the current limiting circle Cis is an allowable current value iqm (predetermined value) of the switching elements SUX to SWZ. That is, the current limiting circle Cis intersects the q axis at the point (0, iqm) and intersects the d axis at the point (−iqm, 0). The current limiting circle Cis is determined by the equation (1) in the dq-axis current characteristics.
Idt ² + Iqt ² = iqm ² Equation (1)

Further, the voltage limiting circle Cvs is determined by the equation (2) in the dq-axis current characteristics of the electric motor MTR.
{Idt + (φ / L)} ² + Iqt ² = {Eba / (L · ω)} ² Equation (2)
Here, “Eba” is the power supply voltage (that is, the voltage of the storage battery BAT and the generator ALT), “L” is the phase inductance, and “φ” is the number of interlinkage magnetic fluxes (magnet strength). “Ω” is the electric angular velocity of the electric motor MTR. Note that the electric angular velocity ω is a time change amount of the electric angle θ of the electric motor MTR (an angle in which one cycle of the magnetic field of the electric motor MTR is expressed as 2π [rad]), and is calculated from the rotation angle Mka.

  The voltage limiting circle Cvs is represented as a circle having the coordinates of the center Pcn (idc, 0) of (− (φ / L), 0) and a radius of “Eba / (L · ω)”. The power supply voltage Eba is a predetermined value (constant), and “ω” increases as the rotation speed dMk increases. Therefore, the radius of the voltage limiting circle Cvs decreases as the rotation speed dMk increases, and the radius of the voltage limiting circle Cvs increases as the rotation speed dMk decreases. In the first processing example, it is assumed that the center Pcn is outside the current limiting circle Cis. Therefore, the relationship of “(φ / L)> iqm” is established.

  The case where the rotation speed dMk (that is, the electrical angular speed ω) is relatively large is illustrated by a voltage limiting circle Cvs: a. In this state, in the mutual relationship between the current limiting circle Cis and the voltage limiting circle Cvs: a, the current limiting circle Cis and the voltage limiting circle Cvs: a intersect at points Pxa: a and Pxb: a. In this state, the intersection Pxa: a is in the second quadrant and the intersection Pxb: a is in the third quadrant, so the processing in step S160 is denied.

  Next, in the process of step S170, the value of the compensation instruction current Imr is considered as the q-axis target current Iqt (q-axis component). For example, if “Imr = iq1 (> Iqx)” and “Imr ≧ Iqx” in step S170 is satisfied, “Idt = Idx, Iqt = Iqx” is calculated in step S210. That is, as the target current Imt, a vector Imt: 1 (a vector from the origin O to the intersection Pxa: a) is calculated.

  On the other hand, if “Imr = iq2 (<Iqx)” and “Imr ≧ Iqx” is denied in step S170, then in step S215, if “Iqt = iq2” on the voltage-limited circle Cvs: a Is calculated as the voltage-limited circle d-axis coordinate Ids (variable). Next, in step S220, “Idt = Ids, Iqt = Imr (= iq2)” is calculated. That is, the vector Imt: 2 is calculated as the target current Imt.

  In energizing the electric motor MTR, in the current feedback control, the dq-axis current that can actually flow is an area where the current limiting circle Cis and the voltage limiting circle Cvs overlap (an energizable area indicated by hatching). The intersection Pxa: a on the boundary of the energizable region is the point where the output (the work amount per unit time, the power) is maximized. Therefore, when the rotation speed dMk is relatively large and the compensation instruction current Imr is relatively large, the vector Imt is set as the target current Imt so that the output (power) of the electric motor MTR is maximized. : 1 is determined.

  The case where the rotation speed dMk is relatively low is illustrated by a voltage limiting circle Cvs: b. In this state, in the mutual relationship between the current limiting circle Cis and the voltage limiting circle Cvs: b, the current limiting circle Cis and the voltage limiting circle Cvs: b intersect at points Pxa: b and Pxb: b. In this state, the intersection Pxa: b is in the first quadrant and the intersection Pxb: b is in the fourth quadrant, so the processing in step S160 is affirmed.

  Next, in the process of step S180, the value of the compensation instruction current Imr is considered as the q-axis target current Iqt (q-axis component of the target current Imt). For example, if “Imr = iq3 (> iqm)” and “Imr ≧ iqm” in step S180 is satisfied, “Idt = 0, Iqt = iqm” is calculated in step S230. That is, a vector Imt: 3 (a vector from the origin O to the point (0, iqm)) is calculated as the target current Imt. On the other hand, if “Imr = iq1 (<iqm)” and “Imr ≧ iqm” in step S180 is denied, then “Idt = 0, Iqt = Imr (= iq1)” is calculated in step S240. .

  When the rotation speed dMk is relatively low, the magnetic flux weakening control is unnecessary, and “Idt = 0” is set. There is a trade-off between the d-axis current and the q-axis current. Therefore, by setting the d-axis target current Idt to “0”, the q-axis target current Iqt acting in the torque direction can be used to the maximum in energizing the electric motor MTR.

  When the rotation speed dMk is relatively low, the point (0, iqm) on the boundary of the energizable area is the point of maximum output. Therefore, when the compensation instruction current Imr is instructed beyond the q-axis maximum current iqm, the compensation instruction current Imr is limited to the q-axis maximum current iqm. On the other hand, when the compensation instruction current Imr is less than the q-axis maximum current iqm, the compensation instruction current Imr is not limited and is set as the target current Imt.

  The case where the rotation speed dMk is further lower and the electric motor MTR is substantially stopped is illustrated by a voltage limiting circle Cvs: c. In this state, the current limiting circle Cis is included in the voltage limiting circle Cvs: c, and the intersection Px does not exist. Therefore, the process of step S160 is affirmed. As in the case where the intersections are points Pxa: b and Pxb: b, it is determined in step S180 whether or not “Imr ≧ iqm”, and based on the determination result, “Idt = 0, Iqt = iqm ( "Process of step S230)" or "Idt = 0, Iqt = Imr (process of step S240)" is calculated.

<Second processing example in target current calculation block IMT>
A second processing example in the target current calculation block IMT will be described with reference to the flowchart of FIG. 7 and the characteristic diagram of FIG. In the second processing example, as in the first processing example, the case where the electric motor MTR is driven in the normal rotation direction will be described.

  The first processing example corresponds to the case where the center Pcn of the voltage limiting circle Cvs is located outside the current limiting circle Cis, while the second processing example corresponds to the case where the center Pcm (ide, 0) of the voltage limiting circle Cvs is This corresponds to the case where it is located inside the current limiting circle Cis. First, the flow of processing will be described with reference to the flowchart of FIG.

  In step S310, the command current Ims, the compensation current Ifp, the rotation angle Mka, and the current limiting circle Cis are read. The current limiting circle Cis is set in advance based on the specifications of the drive circuit DRV (see equation (1)). The current limiting circle Cis is determined from the rated currents iqm of the switching elements SUX to SWZ in the dq-axis current characteristics (Idt-Iqt plane) of the electric motor MTR.

  In step S320, the compensation current (compensation current based on the pressing force feedback control) Ifp is added to the command current Ims, and the compensation instruction current (the command current after the compensation based on the pressing force feedback control) Imr is calculated. Is done. In step S330, the electrical angle θ is determined from the rotation angle (mechanical angle) Mka, and this is time-differentiated to calculate the electrical angular velocity ω. In step S340, the voltage limiting circle Cvs is calculated based on the electric angular velocity ω and the equation (2).

  In step S350, based on the current limiting circle Cis and the voltage limiting circle Cvs, an intersection Px (general term for Pxa and Pxb) is calculated in the dq-axis current characteristics. In addition to the states described in the first processing example, when the rotation speed dMk is very high, the voltage limiting circle Cvs is included in the current limiting circle Cis, and the intersection Px may not exist.

  In step S360, "whether or not the intersection points Pxa (Idx, Iqx) and Pxb (Idx, -Iqx) exist in the first and fourth quadrants on the dq-axis current plane" or "Current limit circle" Whether or not Cis is included in the voltage limiting circle Cvs ”is determined. When the intersection Px exists in the first and fourth quadrants and step S360 is affirmed (in the case of "YES"), the process proceeds to step S400. On the other hand, if the intersection Px is in the second or third quadrant and step S360 is negative ("NO"), the process proceeds to step S370. If the current limiting circle Cis is included in the voltage limiting circle Cvs and there is no intersection Px, step S360 is affirmed and the process proceeds to step S400.

  In step S370, it is determined whether “the voltage limiting circle Cvs is included in the current limiting circle Cis or not” or “whether the d-axis coordinate Idx of the intersection Px is equal to or less than the value ide”. Here, the value ide is the d-axis coordinate of the center Pcm of the voltage-limited circle Cvs, and is referred to as “center d-axis coordinate”. The center d-axis coordinate ide is a predetermined value determined in advance from the relationship between the phase inductance L and the number of interlinkage magnetic fluxes φ, and specifically, is equal to “φ / L”. If “voltage limit circle Cvs is included in current limit circle Cis” or “Idx ≦ iqe” and step S370 is affirmative (“YES”), the process proceeds to step S390. On the other hand, if “voltage limit circle Cvs is not included in current limit circle Cis” and “Idx> iqe” and step S370 is denied (“NO”), the process proceeds to step Proceed to S380.

  In step S380, based on the compensation instruction current Imr and the intersection Pxa (Idx, Iqx), it is determined whether "the compensation instruction current Imr is equal to or greater than the intersection q-axis coordinate Iqx". If “Imr ≧ Iqx” and step S380 is affirmative (“YES”), the process proceeds to step S410. On the other hand, if “Imr <Iqx” and step S380 is negative (“NO”), the process proceeds to step S415. The command current Imr is a value larger than “0” so that the electric motor MTR is driven in the normal rotation direction.

  In step S390, “whether or not the compensation instruction current Imr is equal to or larger than the q-axis intersection Iqp of the voltage limitation circle Cvs” is determined based on the compensation instruction current Imr and the voltage limiting circle Cvs. Here, the value Iqp is referred to as a “voltage limit circle maximum value”. If “Imr ≧ Iqp” and step S390 is affirmed (“YES”), the process proceeds to step S430. On the other hand, if “Imr <Iqp” and step S390 is negative (“NO”), the process proceeds to step S435.

  In step S400, based on the compensation instruction current Imr and the current limiting circle Cis, it is determined whether “the compensation instruction current Imr is equal to or greater than the q-axis intersection iqm of the current limiting circle Cis”. If “Imr ≧ iqm” and step S400 is affirmed (“YES”), the process proceeds to step S450. On the other hand, if “Imr <iqm” and step S400 is denied (“NO”), the process proceeds to step S460.

  In step S410, the d-axis target current Idt is determined as the intersection d-axis coordinate Idx (variable), and the q-axis target current Iqt is determined as the intersection q-axis coordinate Iqx (variable). In step S415, the voltage-restricted circle d-axis coordinates Ids (d-axis coordinates when “Iqt = Imr” on the voltage-limited circle Cvs) are calculated based on the compensation instruction current Imr and the voltage-restricted circle Cvs. You. Then, in step S420, it is determined that the d-axis target current Idt matches the restricted circle d-axis coordinate Ids and the q-axis target current Iqt matches the compensation instruction current Imr.

  In step S430, the d-axis target current Idt is determined to be the center d-axis coordinate ide (predetermined value), and the q-axis target current Iqt is determined to be the voltage limiting circle maximum value Iqp (variable). In step S435, as in step S415, the voltage-limiting circle d-axis coordinate Ids is calculated based on the compensation instruction current Imr and the voltage-limiting circle Cvs. Then, in step S440, it is determined that the d-axis target current Idt matches the limited circle d-axis coordinate Ids and the q-axis target current Iqt matches the compensation instruction current Imr. In step S450, the d-axis target current Idt is determined to be “0”, and the q-axis target current Iqt is determined to be the q-axis maximum current iqm. In step S460, the d-axis target current Idt is determined to be “0”, and the q-axis target current Iqt is determined to be equal to the compensation instruction current Imr.

<< Relationship between the current limiting circle Cis and the voltage limiting circle Cvs in the second processing example >>
Next, the processing in each step of the second processing example will be described with reference to the characteristic diagram of FIG. As in the description of the first processing example, it is assumed that the electric motor MTR is driven in the normal rotation direction, and the compensation instruction current Imr is calculated as a positive value on the q axis.

  The current limiting circle Cis is determined based on the rated current iqm of the switching elements forming the bridge circuit BRG, as in the first processing example. Specifically, the current limiting circle Cis is determined as a circle centered on the origin O (0, 0) and having a radius of iqm in the dq-axis current characteristics (see Equation (1)). Therefore, the current limiting circle Cis intersects the q axis at the point (0, iqm).

  The voltage limiting circle Cvs is determined based on the power supply voltage Eba, the phase inductance L, the number of interlinkage magnetic fluxes φ, and the electric angular velocity ω in the dq-axis current characteristics of the electric motor MTR (see Expression (2)). The state variable in the voltage limiting circle Cvs is the electrical angular velocity ω, which is calculated from the rotation angle Mka.

  The voltage limiting circle Cvs is a circle having coordinates of the center Pcm (ide, 0) of (− (φ / L), 0) and a radius of “Eba / (L · ω)”. The radius of the voltage limiting circle Cvs decreases as the rotation speed dMk increases, and the radius of the voltage limiting circle Cvs increases as the rotation speed dMk decreases. In the second processing example, it is assumed that the center Pcm is inside the current limiting circle Cis. Therefore, the relationship “(φ / L) <iqm” is established.

  The case where the rotation speed dMk is very large is illustrated by a voltage limiting circle Cvs: d. In this state, in the relationship between the current limiting circle Cis and the voltage limiting circle Cvs: d, the voltage limiting circle Cvs: d is included in the current limiting circle Cis, and the intersection Px does not exist. A negative determination is made in step S360, a positive determination is made in step S370, and a determination process in step S390 is performed. If the compensation instruction current Imr is equal to or greater than the voltage limit circle maximum value Iqp, the process proceeds to step S430. In step S430, the d-axis target current Idt is set to the center d-axis coordinate ide, and the q-axis target current Iqt is limited to the voltage limiting circle maximum value Iqp. That is, a vector Imt: 4 (a vector from the origin O to the point R) is calculated as the target current Imt.

  On the other hand, when compensation instruction current Imr is less than voltage limit circle maximum value Iqp (for example, when “Imr = iq4 (<Iqp)”), the process proceeds from step S390 to step S435. In step S435, on the voltage-limited circle Cvs: d, the d-axis coordinates when “Iqt = iq4” are calculated as the voltage-limited circle d-axis coordinates Ids (variable) (that is, the same as step S215). processing). Then, in step S440, the d-axis target current Idt is set to the limited circle d-axis coordinate Ids, and the compensation instruction current Imr is not limited and is determined as the q-axis target current Iqt. That is, the vector Imt: 5 is calculated as the target current Imt.

  The case where the rotation speed dMk is slightly reduced from the state of the voltage limit circle Cvs: d is illustrated by the voltage limit circle Cvs: e. In this state, in the correlation between the current limiting circle Cis and the voltage limiting circle Cvs, the voltage limiting circle Cvs: e is not included in the current limiting circle Cis, and intersections Pxa: e and Pxb: e exist. However, the d-axis coordinate Idx of the intersection Pxa: e is smaller than the d-axis coordinate ide of the center Pcm. In this state, as in the case where the voltage limiting circle Cvs is included in the current limiting circle Cis, the determination in step S360 is negative, the determination in step S370 is affirmative, and the determination process in step S390 is executed. If the compensation instruction current Imr is equal to or greater than the voltage limit circle maximum value Iqp, the process proceeds to step S430. In step S430, the d-axis target current Idt is set to the center d-axis coordinate ide, and the q-axis target current Iqt is limited to the voltage limiting circle maximum value Iqp. That is, a vector Imt: 6 (a vector from the origin O to the point S) is calculated as the target current Imt. Note that the maximum voltage limit circle value Iqp is larger than the q-axis coordinate Iqx of the intersection Pxa: e (Ipq> Iqx). Therefore, the output of the electric motor MTR is more increased when controlled at the point S (ide, Iqp) than when controlled at the intersection Pxa: e.

  On the other hand, if the compensation instruction current Imr is less than the voltage limit circle maximum value Iqp, the process proceeds from step S390 to step S435, where the limit circle d-axis coordinate Ids is calculated. Then, in step S440, the d-axis target current Idt is set to the limited circle d-axis coordinate Ids, and the compensation instruction current Imr is not limited and is determined as the q-axis target current Iqt.

  Further, a case where the rotation speed dMk is slightly reduced from the state of the voltage limit circle Cvs: e is illustrated by a voltage limit circle Cvs: f. In this state, in the correlation between the current limiting circle Cis and the voltage limiting circle Cvs, the voltage limiting circle Cvs: f is not included in the current limiting circle Cis, and intersections Pxa: f and Pxb: f exist. The d-axis coordinate Idx of the intersection Pxa: f is larger than the d-axis coordinate ide of the center Pcm. In this state, the determination in step S360 is negative, the determination in step S370 is negative, and the determination process in step S380 is performed. If the compensation instruction current Imr is equal to or greater than the intersection q-axis coordinate Iqx, the process proceeds to step S410. In step S410, the d-axis target current Idt is set to the intersection d-axis coordinate Idx, and the q-axis target current Iqt is limited to the intersection q-axis coordinate Iqx. That is, a vector Imt: 7 (a vector from the origin O to the point Pxa: f) is calculated as the target current Imt. In step S410, the same processing as in step S210 is performed.

  On the other hand, if the compensation instruction current Imr is less than the intersection q-axis coordinate Iqx, the process proceeds from step S380 to step S415, where the restricted circle d-axis coordinate Ids is calculated. Then, in step S420, the d-axis target current Idt is set to the limited circle d-axis coordinate Ids, and the compensation instruction current Imr is not limited and is determined as the q-axis target current Iqt. In steps S415 and S420, the same processing as in steps S215 and S220 is performed.

  The case where the rotation speed dMk becomes relatively small is illustrated by a voltage limiting circle Cvs: g and a voltage limiting circle Cvs: h. The voltage limitation circle Cvs: g corresponds to the voltage limitation circle Cvs: b, and the voltage limitation circle Cvs: h corresponds to the voltage limitation circle Cvs: c. Therefore, as in the first processing example, in these states, if “Imr ≧ iqm” in step S400 is satisfied, “Idt = 0, Iqt = iqm” is calculated in step S450. On the other hand, if “Imr ≧ iqm” in step S400 is negative, “Idt = 0, Iqt = Imr” is calculated in step S460. Step S450 corresponds to step S230, and step S460 corresponds to step S240.

  In energizing the electric motor MTR, the current of the dq axes that can actually flow by the current feedback control is an area where the current limiting circle Cis and the voltage limiting circle Cvs overlap (an energizable area). The intersection Px on the boundary of the energizable region is a point where the output (the amount of work per unit time) is maximum. For this reason, similarly to the first processing example, in the second processing example, when the rotation speed dMk is relatively large and the compensation instruction current Imr is relatively large, the output of the electric motor MTR is maximum. As a result, the vector Imt: 7 is determined as the target current Imt.

  When the rotation speed dMk is relatively low, the magnetic flux weakening control is unnecessary, and “Idt = 0” is set. There is a trade-off between the d-axis current and the q-axis current. Therefore, by setting the d-axis target current Idt to “0”, the q-axis target current Iqt acting in the torque direction can be used to the maximum in energizing the electric motor MTR.

  When the rotation speed dMk is relatively low, the point (0, iqm) on the boundary of the energizable area is the point of maximum output. Therefore, when the compensation instruction current Imr is instructed beyond the q-axis maximum current iqm, the compensation instruction current Imr is limited to the q-axis maximum current iqm. On the other hand, when the compensation instruction current Imr is less than the q-axis maximum current iqm, the compensation instruction current Imr is not limited and is set as the target current Imt.

  When the rotation speed dMk is very large and the voltage limit circle Cvs is included in the current limit circle Cis, or the d-axis coordinate Idx of the intersection Px of the voltage limit circle Cvs and the current limit circle Cis is set at the center of the voltage limit circle Cvs. When Pcm is smaller than the d-axis coordinate ide, the intersections R and S between the “straight line Lcm passing through the center Pcm and parallel to the q-axis (referred to as“ q-axis parallel line ”)” and the voltage-limiting circle Cvs have the maximum output. Point. In such a situation, the target current Imt is not determined based on the intersection Px, but is determined based on the intersection (for example, points R and S) of the q-axis parallel line Lcm and the voltage limiting circle Cvs. It is determined. As a result, the electric motor MTR can be efficiently driven.

<Action and Effect and Other Embodiments>
The vehicle brake control device BCS according to the present invention will be summarized. In determining the target current vector Imt, the d-axis and q-axis current characteristics (Idt-Iqt characteristics) include a current limiting circle Cis determined from the specifications of the drive circuit DRV (for example, the allowable current of the switching element) and a rotation angle Mka. The relationship with the voltage limiting circle Cvs determined based on the above is taken into consideration. Specifically, a voltage limiting circle Cvs is created on the dq-axis current characteristics, and the d-axis and q-axis target currents Idt and Iqt are determined based on the correlation between the current limiting circle Cis and the voltage limiting circle Cvs. . Here, the current that can actually flow through the electric motor MTR by the current feedback control is, in a mutual relationship, a range in which the current limiting circle Cis and the voltage limiting circle Cvs overlap (an energizable area). If the electric motor MTR is controlled outside the energizable region, it is inefficient in driving the electric motor MTR, and sometimes an overload (current exceeding the rated current) may be applied to the switching element.

  The voltage limiting circle Cvs is affected by the electrical angular velocity ω. For this reason, the mutual relationship changes according to the rotation speed dMk. When the voltage limiting circle Cvs intersects with the current limiting circle Cis, the d-axis and q-axis target currents Idt, Iqt is calculated (see FIGS. 6 and 8). This is because the output of the electric motor MTR (work per unit time, power) becomes maximum at the intersection Px. By determining the target current vector Imt (Idt, Iqt) by the intersection Px, efficient driving of the electric motor MTR (maintaining high-speed rotation and outputting high torque) can be achieved.

  When the rotation speed dMk is small and the current limiting circle Cis is included in the voltage limiting circle Cvs, the energizable region matches the current limiting circle Cis. In this case, the d-axis target current Idt is set to “0” based on the point (0, iqm) where the q-axis current Iqt is maximum in the current limiting circle Cis, and the q-axis target current Iqt is calculated. Although there is a trade-off relationship between the dq-axis currents, this enables the electric motor MTR to output a sufficient torque.

  Further, in the correlation, “when the voltage-limited circle Cvs is included in the current-limited circle Cis” or “the d-axis coordinate Idx of the intersection Px is more negative than the d-axis coordinate ide of the center Pcm of the voltage-limited circle Cvs. , The d-axis and q-axis target currents Idt and Iqt are calculated based on the vertices R and S at which the q-axis current Iqt is maximum in the voltage-limited circle Cvs (see FIG. 8). This is because the output (the work per unit time) of the electric motor MTR becomes maximum at the vertices R and S. Note that the vertices R and S are the intersections of the “straight line Lcm (q-axis parallel line) parallel to the q-axis passing through the center Pcm” and the voltage limiting circle Cvs.

  Next, another embodiment will be described. In the other embodiments, the same effect as described above (both efficient driving of the electric motor MTR and compatibility of trade-off) can be obtained.

In the above embodiment, it has been exemplified that the voltage limiting circle Cvs is calculated using Expression (2). In the calculation of the voltage limiting circle Cvs, a voltage drop due to a current flowing through the electric motor MTR may be considered. The voltage drop is considered as “(R · Iqa) / (L · ω)” for the d-axis current and “(R · Ida) / (L · ω)” for the q-axis current. . Specifically, the voltage limiting circle Cvs is calculated by Expression (3).
{Idt + (φ / L) + (R · Iqa) / (L · ω)} ² + {(R · Ida) / (L · ω) −Iqt} ² = {Eba / (L · ω)} ² ... Equation (3)
Here, “Eba” is the power supply voltage (that is, the voltage of the storage battery BAT and the generator ALT), “L” is the phase inductance, “φ” is the number of interlinkage magnetic fluxes (magnet strength), and “R” is This is the winding resistance. “Ω” is the electric angular velocity of the electric motor MTR, and is calculated based on the rotation angle Mka. Further, “Ida” is the d-axis actual current, and “Iqa” is the q-axis actual current, which is calculated based on the detection value Ima of the current sensor IMA (see FIG. 3).

In the equation (3), the voltage drop is considered based on the d-axis and q-axis actual currents Ida and Iqa. Instead of the d-axis and q-axis actual currents Ida and Iqa, the d-axis and q-axis target currents Idt [n-1] and Iqt [n-1] of the previous calculation cycle are employed. That is, the voltage drop is considered based on the d-axis and q-axis target currents Idt [n-1] and Iqt [n-1] in the previous calculation cycle, and the d-axis and q-axis target currents Idt [ n], Iqt [n]. Here, [n] at the end of the symbol indicates the current operation cycle, and [n-1] indicates the previous operation cycle. Specifically, the voltage limiting circle Cvs is calculated by equation (4).
{Idt [n] + (φ / L) + (R · Iqt [n−1]) / (L · ω)} ² + ｛(R · Idt [n−1]) / (L · ω) −Iqt [n]｝ ² = {Eba / (L · ω)} ² ... Equation (4)

  As shown in Expression (3) or Expression (4), more accurate driving of the electric motor MTR can be achieved by considering the voltage drop.

  In the above embodiment, in the calculation of the electric angular velocity ω of the electric motor MTR, the electric angle θ is calculated based on the rotation angle Mka (mechanical angle) of the electric motor MTR, and the electric angle θ is time-differentiated. Calculated. That is, the electrical angular velocity ω is determined in the order of “Mka → θ → ω”. Alternatively, the rotation speed dMk may be calculated based on the rotation angle Mka, and the electrical angular speed ω may be calculated based on the rotation speed dMk. That is, the electrical angular velocity ω can be determined in the order of “Mka → dMk → ω”. However, in any case, the voltage limiting circle Cvs in the dq-axis current characteristics is calculated based on the rotation angle Mka detected by the rotation angle sensor MKA.

  In the above embodiment, the configuration of the disc-type braking device (disc brake) has been exemplified. In this case, the friction member MS is a brake pad, and the rotating member KT is a brake disk. Instead of the disc type braking device, a drum type braking device (drum brake) may be employed. In the case of a drum brake, a brake drum is employed instead of the caliper CP. Further, the friction member MS is a brake shoe, and the rotating member KT is a brake drum.

  In the above-described embodiment, an example in which the braking force is applied to one wheel WH by the pressurizing unit KAU has been described. However, the braking force of the plurality of wheels WH can be generated by the pressurizing unit KAU. In this case, a plurality of wheel cylinders WC are connected to the fluid path HWC.

  Further, as the pressurizing cylinder KCL, one having two hydraulic chambers partitioned by two pressurizing pistons may be employed. That is, a tandem type configuration is employed for the pressurizing cylinder KCL. Then, two wheel cylinders WC of the four wheels WH are connected to one hydraulic chamber, and the remaining two wheel cylinders WC of the four wheels WH are connected to the other hydraulic chamber. . As a result, a so-called front-back or diagonal fluid configuration using the pressure cylinder KCL as a hydraulic pressure source can be formed.

  In the above embodiment, the configuration of the hydraulic braking control device in which the rotational power of the electric motor MTR is converted into the hydraulic pressure of the wheel cylinder WC via the braking fluid and the braking force is generated on the wheel WH is illustrated. Was. Instead, an electromechanical brake control device that does not use a brake fluid may be employed. In this case, the KAU is mounted on the caliper CP. Further, a thrust sensor is employed as the pressing force sensor FPA instead of the hydraulic pressure sensor. For example, the thrust sensor may be provided between the power transmission mechanism DDK and the pressurizing piston PKC, as indicated by “(FPA)” in FIG.

  Further, a composite structure may be formed in which a hydraulic pressurizing unit through the brake fluid is used for the front wheels, and an electromechanical pressurizing unit is used for the rear wheels.

BP: braking operation member, MTR: electric motor (three-phase brushless motor), KAU: pressurizing unit, ECU: controller, DRV: drive circuit, BPA: operation amount sensor, MKA: rotation angle sensor, IMA: current sensor, Cvs … Voltage limit circle, Cis… Current limit circle.

Claims (2)

A braking control device for a vehicle that drives an electric motor based on a target pressing force corresponding to a required braking force on wheels of a vehicle and presses a friction member against a rotating member fixed to the wheels to generate a braking force on the wheels. And
A drive circuit for driving the electric motor;
And a controller for controlling the drive circuit based on the target pressure,
A rotation angle sensor for detecting a rotation angle of the electric motor,
A current sensor for detecting an actual current of the electric motor;
With
The controller is
Based on the specifications of the drive circuit, set a current limiting circle in the dq-axis current characteristics of the d-axis current and the q-axis current of the electric motor,
In the dq-axis current characteristics, when the current limiting circle is included in a voltage limiting circle calculated based on the rotation angle,
The intersection of the q axis of the dq axis current characteristic and the current limiting circle is calculated as a d axis and a q axis target current ,
Based on the actual current, d-axis and q-axis actual currents are calculated,
The d-axis, q-axis actual current, the d-axis, and controls the drive circuit so as to match the q-axis target current, brake control apparatus for a vehicle. A braking control device for a vehicle that drives an electric motor based on a target pressing force according to a required braking force on wheels of a vehicle and presses a friction member against a rotating member fixed to the wheels to generate a braking force on the wheels. And
A drive circuit for driving the electric motor;
A controller that controls the drive circuit based on the target pressing force,
A rotation angle sensor for detecting a rotation angle of the electric motor,
A current sensor for detecting an actual current of the electric motor;
With
The controller is
Based on the specifications of the drive circuit, set a current limiting circle in the dq-axis current characteristics of the d-axis current and the q-axis current of the electric motor,
In the dq-axis current characteristics, when a voltage limiting circle calculated based on the rotation angle is included in the current limiting circle,
The intersection of a straight line parallel to the q-axis of the dq-axis current characteristic and the voltage-limiting circle passing through the center of the voltage-limiting circle is calculated as a d-axis and q-axis target current,
Based on the actual current, d-axis and q-axis actual currents are calculated,
A vehicle braking control device that controls the drive circuit so that the d-axis and q-axis actual currents match the d-axis and q-axis target currents.