Vehicle braking system

Abstract

To provide a brake for vehicle that uses an electric brake having hysteresis characteristics and that executes technique of hysteresis utilizing current reduction processing, stop position adjustment processing, or phase adjustment processing properly in combination in holding brake force.SOLUTION: The relation between torque of a motor and brake force that an electric brake generates has hysteresis characteristics. Processing to reduce a drive current and torque of the motor from a positive efficiency line to a reverse efficiency line based upon the hysteresis characteristics while holding the drive force through position control or load control is defined as "hysteresis utilizing current reduction processing". Processing to adjust a rotation stop position through the position control so as to decrease or increase a current absolute value of any phase of interest in lock electricity feeding in a state in which the motor stops rotating in holding the brake force is defined as "stop position adjustment processing". A brake force control part executes the hysteresis utilizing current reduction processing and the stop position adjustment processing.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] This invention relates to a braking system for vehicles. [Background technology]

[0002] Conventionally, in electric braking systems for vehicles where the relationship between motor torque and the pressing force applied to the brake disc by the motion conversion mechanism exhibits hysteresis characteristics, a technique is known for reducing the motor's drive current while maintaining the braking force at a target value.

[0003] For example, in the electric brake device disclosed in Patent Document 1, the motor control device controls the motor drive current based on the magnitude of the pressing force detected by the load sensor. The relationship between motor torque and pressing force has a hysteresis characteristic. When applying and holding a pressing force to the brake disc, this motor control device increases the motor torque until the magnitude of the pressing force detected by the load sensor reaches a predetermined value greater than the target value, and then controls the motor drive current such that the motor torque decreases until the magnitude of the pressing force detected by the load sensor reaches the target value. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 6080682 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In this specification, "pressing force" is replaced with "load." Braking force correlates with load, and the required braking force is reflected in the load command value. When the braking force increases, the operation of increasing the motor torque along the positive efficiency line until the braking force reaches the required braking force is called "increase operation." The operation of increasing the motor torque along the positive efficiency line until the braking force exceeds the required braking force by a predetermined amount is called "excess operation." The operation of decreasing the motor torque while maintaining the braking force at the end of the excess operation is called "holding operation." After the holding operation, the operation of decreasing the motor torque along the negative efficiency line until the braking force reaches the required braking force is called "return operation."

[0006] In the prior art described in Patent Document 1, the motor drive current can be reduced while maintaining braking force, thereby reducing heat generation in the inverter and motor windings. However, due to insufficient accuracy of the load sensor during over-operation and deformation of the pads and discs due to temperature changes, there is a risk of discrepancies between the actual braking force and the required braking force during the holding operation. Furthermore, locking the multi-phase motor is required during the process of maintaining braking force, which leads to a concentration of current in a specific phase and uneven heat generation.

[0007] The applicant has previously filed several patent applications for solutions to these problems. In Japanese Patent Application No. 2022-122869, a technology for hysteresis-based current reduction processing was proposed, which reduces the motor drive current and torque from the positive efficiency line to the negative efficiency line based on hysteresis characteristics.

[0008] Japanese Patent Applications 2022-148195 and 2022-148229 propose a stop position adjustment process that prevents heat generation from being concentrated in a specific phase when the motor is locked and energized, by adjusting the rotation stop position of the motor.

[0009] Japanese Patent Application No. 2021-196167 proposes a phase adjustment process that prevents heat generation from being concentrated in a specific phase during lock energization by changing the current phase of the dq axis current according to time so that energization with the same current phase is not continued for longer than a predetermined time.

[0010] These technologies proposed by the applicant can be used in combination. The object of the present invention is to provide a vehicle braking system that uses an electric brake having hysteresis characteristics and appropriately combines and executes technologies such as hysteresis-utilizing current reduction processing, stop position adjustment processing, or phase adjustment processing when maintaining braking force. [Means for solving the problem]

[0011] The vehicle braking system of the present invention is mounted on a vehicle (900) in which a multiphase motor (60) outputs torque, which is converted into linear power by a linear motion mechanism (85), and multiple electric brakes (81-84) are provided on each wheel to press against the corresponding wheels (91-94) and generate braking force.

[0012] The vehicle braking system includes a torque command calculation unit (40) and a current command calculation unit (50), and is equipped with a braking force control unit (400) that controls the braking force generated by each electric brake. The torque command calculation unit calculates the torque command value of the motor based on the requested braking force commanded from an external source. The current command calculation unit calculates the current command value to energize the motor based on the torque command value.

[0013] This invention To be hired In the first embodiment, the electric brake is equipped with position sensors (72, 73) that detect the actual rotation angle of the motor or the actual position (θ, X) which is the actual stroke of the linear motion mechanism, or, in addition to the position sensors, a load sensor (71) that detects the actual load (F) which is the braking load actually pressed on the wheel.

[0014] The relationship between motor torque and the braking force generated in the electric brake exhibits a hysteresis characteristic: when torque increases, the braking force increases along the positive efficiency curve; when torque decreases from the turning point where it changes from increasing to decreasing to the holding critical value, the braking force is maintained constant; and when torque decreases from the holding critical value, the braking force decreases along the negative efficiency curve.

[0015] The torque command calculation unit calculates the position command value (θ) from the actual position detected by the position sensor.* , X * Either perform position control that calculates the torque command value to approach ) or use the actual load detected by the load sensor to calculate the load command value (F based on the required braking force) * Load control, which calculates the torque command value to approximate the target value, and position control can be switched between these two functions.

[0016] The process of reducing the motor's drive current and torque from the positive efficiency line to the negative efficiency line based on hysteresis characteristics while maintaining braking force through position control or load control is defined as "hysteresis-based current reduction processing."

[0017] In lock current application, where power is supplied to the motor while it is stopped rotating to maintain braking force, the process of adjusting the rotation stop position by position control so as to decrease or increase the absolute value of the current of any phase of interest is defined as "stop position adjustment process".

[0018] The hysteresis-based current reduction process includes an overdrive operation in which the motor torque is increased along the positive efficiency line until the actual braking force, which is the braking force actually output by the electric brake, exceeds the required braking force by a predetermined amount, and a return operation in which the motor drive current is reduced while maintaining the braking force at the end of the overdrive operation, and then the motor torque is decreased along the negative efficiency line until the actual braking force reaches the required braking force.

[0019] Here, it is preferable that the hysteresis-based current reduction process and the stop position adjustment process be performed in an appropriate order. If, after the hysteresis-based current reduction process moves the operating point to the inverse efficiency line, the stop position adjustment process then adjusts the braking force to the increased side, the operating point will move back to the positive efficiency line, and the maximum current reduction effect will not be obtained. 。

[0020] Therefore, when the braking force control unit maintains the braking force, Executes excessive operation of hysteresis-based current reduction processing. did rear , hysteresis-based current reduction processing The above phenomenon can be avoided by performing a stop position adjustment process that adjusts the motor's rotation stop position in the direction of decreasing braking force, while also performing a return operation. In other reference embodiments, the above phenomenon is avoided by performing a hysteresis-based current reduction process after performing a stop position adjustment process. In the first embodiment, both the effect of reducing current during braking force maintenance and the effect of preventing uneven heat generation to a specific phase can be obtained.

[0021] Furthermore, the current command calculation unit calculates a current command value defined by the current amplitude and current phase in the dq axis coordinates based on the torque command value. In lock energization, the process of changing the phase of the current command value according to time so as not to continue energizing with the same current phase for longer than a predetermined time is defined as "phase adjustment processing".

[0022] Furthermore, when performing phase adjustment processing, it is preferable for the braking force control unit to perform the phase adjustment processing after performing the stop position adjustment processing and the hysteresis-utilizing current reduction processing. The appropriate adjustment direction and amount in phase adjustment control vary depending on the motor's rotation stop position and output torque. Therefore, it is efficient and effective to perform the phase adjustment processing after the motor's position and torque have finished changing due to the stop position adjustment processing or the hysteresis-utilizing current reduction processing.

[0023] As a reference example In the second embodiment, it is not a requirement that the electric brake be equipped with a position sensor or that the torque command calculation unit perform position control. The phrase "by position control or load control" is deleted from the definition of the hysteresis-utilizing current reduction process. When the braking force control unit maintains the braking force, it performs the hysteresis-utilizing current reduction process, and then performs the phase adjustment process. In the second embodiment, both the effect of reducing the current when maintaining the braking force and the effect of preventing uneven heat generation to a specific phase can be obtained.

[0024] As a reference example In a third embodiment, the electric brake is equipped with position sensors (72, 73), and the torque command calculation unit performs at least position control. When the braking force control unit maintains the braking force, it performs a stopping position adjustment process, and then performs a phase adjustment process.

[0025] In the stopping position adjustment process, the range of position adjustment may be limited by the allowable variation range of the required load. In such cases, combining it with phase adjustment processing can prevent uneven heat generation to a specific phase, which is particularly effective. [Brief explanation of the drawing]

[0026] [Figure 1] A diagram showing the configuration of a vehicle equipped with the vehicle braking system of this embodiment. [Figure 2] A schematic diagram of the electric brakes corresponding to each wheel. [Figure 3] (a) Schematic diagram of the pads of an electric brake, (b) Characteristic diagram of pad load and pad position. [Figure 4] A diagram illustrating braking force control under load control using a comparative example. [Figure 5] A schematic block diagram of the Type A braking force control unit. [Figure 6] A schematic block diagram of the Type B braking force control unit. [Figure 7] Overall scheme diagram of the braking force maintenance operation according to the first (third) embodiment. [Figure 8] (a) Flowchart for determining the transition from stop position adjustment processing to hysteresis-based current reduction processing. (b) Flowchart for determining the transition from hysteresis-based current reduction processing to phase adjustment processing. [Figure 9] Overall scheme diagram of braking force maintenance operation according to the second (fourth) embodiment. [Figure 10] A flowchart for determining the transition from the return operation and stop position adjustment process to the phase adjustment process in the hysteresis-based current reduction process. [Figure 11] Overall scheme diagram of the braking force maintenance operation according to the fifth embodiment. [Figure 12] Overall scheme diagram of the braking force maintenance operation according to the sixth embodiment. [Figure 13] Block diagram of the torque command calculation unit according to the H1 and H2 embodiments of the hysteresis-utilizing current reduction process. [Figure 14] A diagram illustrating the switching between load control and position control according to the H1 embodiment. [Figure 15] A diagram showing the switching between load control and position control according to a modified example of the H1 embodiment. [Figure 16] A diagram showing the switching between load control and position control according to the H2 embodiment. [Figure 17] Block diagram of the torque command calculation unit of the H3 embodiment. [Figure 18]This figure shows braking force control in position control according to the H3 embodiment. [Figure 19] Flowchart of the operation switching process when the required braking force increases. [Figure 20] A flowchart for position command calculation. [Figure 21] A block diagram showing an example of the configuration of the braking force control unit according to the L1 embodiment of the stop position adjustment process. [Figure 22] A diagram showing the stopping position relative to the required load in a comparative example. [Figure 23] A three-phase current waveform diagram showing example 1 of the lock current application position in a comparative example. [Figure 24] A diagram showing the stopping position relative to the required load in the L1 embodiment. [Figure 25] A three-phase current waveform diagram showing an example 1 of the locked energization position in the L1 embodiment. [Figure 26] A diagram comparing the current during locking before and after adjustment of the stopping position. [Figure 27] A three-phase current waveform diagram showing example 2 of the lock current application position in the comparative example. [Figure 28] A three-phase current waveform diagram showing an example 2 of the locked energization position in the L1 embodiment. [Figure 29] This diagram compares the relationship between the high-current phase and the high-heat-dissipating phase when the lock is energized, before and after adjusting the stopping position. [Figure 30] Flowchart for the stop position adjustment process. [Figure 31] A flowchart for determining whether an exemption condition is met. [Figure 32] A block diagram showing an example of the configuration of the braking force control unit according to the L2 embodiment of the stop position adjustment process. [Figure 33] A block diagram showing an example configuration of the braking force control unit according to the P1-P3 embodiment of the phase adjustment process. [Figure 34] Current vector diagram showing the point of maximum efficiency operating in dq axis coordinates. [Figure 35] This diagram shows the relationship between the motor position (electrical angle) and the three-phase current when driven at the point of maximum efficiency. [Figure 36] Time chart of three-phase current when locked. [Figure 37] A current vector diagram showing the phase adjustment process on an equitorque curve according to the P1 embodiment. [Figure 38] This figure shows the relationship between the phase angle and the three-phase current due to the phase adjustment process in the P1 embodiment. [Figure 39] A time chart of the three-phase current during lock energization when the phase adjustment process of the P1 embodiment is performed. [Figure 40] A current vector diagram showing the phase adjustment process on an equiamplitude circle according to the P2 embodiment. [Figure 41] This figure shows the relationship between the phase angle and the three-phase current due to the phase adjustment process in the P2 embodiment. [Figure 42] This figure shows the relationship between the phase angle and torque due to the phase adjustment process in the P2 embodiment. [Figure 43] A current vector diagram illustrating the phase adjustment process in the P3 embodiment. [Modes for carrying out the invention]

[0027] Vehicle braking devices according to multiple embodiments of the present invention will be described based on the drawings. The following Group 1 to Group 6 embodiments include multiple embodiments relating to three types of basic processing. The second and fourth group embodiments correspond to forms of implementing the invention described in the claims. This specification first describes the configurations relating to combinations of the first to sixth group embodiments, and then describes the previously filed content relating to three types of basic processes. In the description of the combinations, "this embodiment" refers to all embodiments that can be combined in each group. In each embodiment, substantially identical components are denoted by the same reference numerals and their descriptions are omitted. To avoid duplication of reference numerals and step numbers in each basic process, some reference numerals and step numbers are changed from those in the previously filed specification and drawings.

[0028] The vehicle braking system of this embodiment is mounted on a vehicle equipped with multiple electric brakes on each wheel, which convert the torque output by a motor into linear motion using a linear motion mechanism and press against the corresponding wheel to generate braking force. The vehicle braking system includes a braking force control unit that controls the braking force generated by each electric brake.

[0029] [Vehicle configuration] Referring to Figures 1 to 3(b), the configuration of the vehicle 900 and electric brakes 81-84 on which the vehicle braking system 30 of this embodiment is mounted will be described. As shown in Figure 1, the vehicle 900 is a four-wheeled vehicle having two rows of left and right pairs of wheels 91, 92, 93, and 94 in the front and rear directions. The front left and right wheels 91 and 92 are labeled "FL" and "FR," and the rear left and right wheels 93 and 94 are labeled "RL" and "RR." Multiple (four in this example) electric brakes 81, 82, 83, and 84 are provided corresponding to each wheel 91, 92, 93, and 94. Hereafter, four consecutive symbols will be abbreviated as "wheels 91-94" and "electric brakes 81-84." The same applies to the symbols "load torque TL1-TL4" and "motor temperature Temp1-Temp4" described later.

[0030] The vehicle braking system 30 includes a braking force control unit 400. The braking force control unit 400 controls the braking force generated by each electric brake 81-84 based on a requested braking force commanded from an external source. The requested braking force is commanded by the driver's brake operation or a braking signal from a driver assistance device. At least a portion of the position sensor signals θ, X, which detect the operating position of the motor or linear motion mechanism constituting each electric brake 81-84, and the load sensor signal F, which detects the pressing load of the brake pad, are input to the braking force control unit 400. Details of each sensor signal θ, X, and F will be described later with reference to Figure 2. Which sensor signals are input to the braking force control unit 400 varies depending on the embodiment. The vehicle braking system 30 also acquires the vehicle speed V from the vehicle speed sensor 97.

[0031] The actuators of the electric brakes 81-84 are composed of a three-phase motor (indicated as "three-phase M" in the figure) 60 as a "multi-phase motor". Specifically, the three-phase motor 60 is a permanent magnet type brushless motor. In other embodiments, a multi-phase motor with four or more phases may be used. In this embodiment, the configuration and operation of the three-phase motor 60 corresponding to each electric brake 81-84 are assumed to be the same, and a single reference numeral "60" is used. In the following specification, the three-phase motor 60 will be abbreviated as simply "motor 60" as appropriate. The braking force control unit 400 includes the functions of four motor control devices that control the energization of the motor 60 of each electric brake 81-84.

[0032] The braking force control unit 400 may acquire load torques TL1-TL4 or motor temperatures Temp1-Temp4. Load torques TL1-TL4 may be estimated from the power consumption of the inverter. Motor temperatures Temp1-Temp4 are detected, for example, by a temperature sensor. Alternatively, the temperature rise may be estimated from the Joule heating caused by energizing the three-phase motor 60 and the motor temperatures Temp1-Temp4 may be calculated by adding this to the ambient temperature. Load torques TL1-TL4 and motor temperatures Temp1-Temp4 will be described later in the explanation of exemptions. If they are not used to determine the exemption requirements, the braking force control unit 400 does not need to acquire load torques TL1-TL4 or motor temperatures Temp1-Temp4.

[0033] In this embodiment, the control configuration of each electric brake 81-84 is the same. Figure 2 illustrates the control configuration of the electric brake by the braking force control unit 400, using one of the electric brakes 81-84 as an example.

[0034] Each electric brake 81-84 includes a motor 60, a linear motion mechanism 85, and a caliper 86. The motor 60 is, for example, a permanent magnet type three-phase brushless motor, and outputs torque by a drive current supplied from the braking force control unit 400. The linear motion mechanism 85 is an actuator that converts the output rotation of the motor 60 into linear motion while reducing its speed. The rotation angle θ of the motor 60 and the stroke X of the linear motion mechanism 85 are proportional. In this way, each electric brake 81-84 converts the torque output by the motor 60 into linear force by the linear motion mechanism 85 and presses it against the corresponding wheel 91-94 to generate braking force.

[0035] The output torque of the motor 60 acts on the pads 87 of the caliper 86 via the linear motion mechanism 85. As the pads 87 move and press against the discs 88 of each wheel 91-94, braking force is generated by friction. The braking force is released when the pads 87 move away from the discs 88.

[0036] Referring to Figures 3(a) and (b), the characteristics of the pad 87 of the electric brake 81-81 shown in section IIIa of Figure 2 will be supplemented. As shown in Figure 3(a), the pad 87 has spring-like characteristics, and the pressing force Fd by the linear motion mechanism 85 and the reaction force Fr corresponding to the amount of strain act in opposite directions. As shown in Figure 3(b), the pad position X based on the stroke of the linear motion mechanism 85 and the pad load F are approximately proportional. If the pad position changes by ΔX due to a change in the rotation angle Δθ of the motor 60, the pad load changes by ΔF. Note that in Figures 3(b) and 24, the symbol "ΔF" indicates the change in load. This has a different meaning from the "ΔF" used in Figures 13, 21, etc., which indicates the load deviation between the load command value and the actual load in load control.

[0037] Returning to Figure 2, the braking force control unit 400 includes a torque command calculation unit 40, a current command calculation unit 50, and an inverter 55. The torque command calculation unit 40 calculates the torque command value Trq of the motor 60 based on the requested braking force commanded from the outside. * The current command calculation unit 50 calculates the torque command value Trq. * Based on this, the current command value Id is defined by the current amplitude and current phase in the dq axis coordinates.* and Iq * are calculated.

[0038] The inverter 55 converts the DC power of the input battery 15 into AC power and supplies the AC power corresponding to the current command values Id * and Iq * to the motor 60. The configuration such as current feedback from the current command calculation unit 50 to the inverter 55 will be described later in the stop position adjustment process and the phase adjustment process.

[0039] Also, the electric brakes 81 - 84 include at least one of the angle sensor 72 shown by the solid line or the stroke sensor 73 shown by the two-dot chain line. The angle sensor 72 detects the actual angle θ which is the actual rotation angle of the motor 60. The stroke sensor 73 detects the actual stroke X which is the actual stroke of the linear motion mechanism 85. The stroke sensor 73 may detect the position change of the moving part of the linear motion mechanism 85 or the position change of the pad 87.

[0040] The angle sensor 72 and the stroke sensor 73 are collectively referred to as the "position sensor". The position sensors 72 and 73 are composed of, for example, Hall elements, magnetoresistive elements, etc., and can detect the position with relatively high accuracy. Also, the actual angle θ and the actual stroke X are collectively referred to as the "actual position". The actual positions θ and X detected by the position sensors 72 and 73 are input to the torque command calculation unit 40. In this embodiment, a configuration mainly including the angle sensor 72 is assumed, and only the symbol of the "position sensor 72" and the symbol of the "actual position θ" are used in the following description. The configuration including the stroke sensor 73 will be described in other embodiments.

[0041] In the Type A configuration described later, the electric brakes 81-84 are further equipped with load sensors 71, indicated by dashed lines. The load sensors 71 detect the actual load F, which is the braking load actually pressed against the wheels 91-94. The load sensors 71 are composed of, for example, load cells, and have lower detection accuracy than the position sensors 72. The actual load F detected by the load sensors 71 is input to the torque command calculation unit 40. In the Type B configuration described later, the electric brakes 81-84 are not equipped with load sensors 71. Note that there may be cases where the actual load F detected by the load sensors 71 is not used in the calculations of the torque command calculation unit 40, but such cases will not be mentioned below.

[0042] Next, referring to Figure 4, the relationship between motor torque and braking force in this configuration of electric brake will be explained. The braking force correlates with the brake pad load. Hereinafter, "torque" simply refers to the torque output by the motor 60, and "load" simply refers to the pressing load by the pad 87. Figure 4 corresponds to Figure 10 of Patent Document 1 (Japanese Patent No. 6080682), and in this specification, it is treated as a comparative example for reasons to be explained later.

[0043] The relationship between the torque of motor 60 and the braking force generated in electric brakes 81-84 exhibits hysteresis characteristics. When the torque increases, the braking force increases along the positive efficiency curve. When the torque decreases from the turning point Tconv, where it begins to decrease, to the holding critical value Tcr, the braking force is maintained constant. When the torque decreases from the holding critical value Tcr, the braking force decreases along the negative efficiency curve. Here, the torque correlates with the drive current of motor 60.

[0044] On the vertical axis, "Fhold" is the target load value, and "dF" is the offset value. "Fex (=Fhold + dF)" is a predetermined value greater than the target value, obtained by adding the offset value to the target value. In the prior art described in Patent Document 1, the motor torque is increased until the magnitude of the load detected by the load sensor reaches a predetermined value Fex that is greater than the target value. Subsequently, the motor drive current is controlled to decrease the motor torque until the magnitude of the load detected by the load sensor reaches the target value.

[0045] The braking force actually output by the electric brakes 61-64 is called the "actual braking force." When the actual braking force is increased to the required braking force and maintained, terms for the first to fourth processes that represent the hysteresis changes of torque and braking force are defined. Figures 4(1) to (4) correspond to the first to fourth processes.

[0046] In the first process, an "increase operation" is performed, in which the torque of the motor 60 is increased along the positive efficiency line until the actual braking force reaches the required braking force. In the second process, following the first process, an "over-operation" is performed, in which the torque of the motor 60 is increased along the positive efficiency line until the actual braking force exceeds the required braking force by a predetermined amount. In the third process, a "holding operation" is performed, in which the torque of the motor 60 is reduced while maintaining the braking force at the end of the over-operation. In the fourth process, a "return operation" is performed, in which the torque of the motor 60 is reduced along the negative efficiency line until the actual braking force reaches the required braking force.

[0047] In Figure 4, the white block arrows attached to the first to fourth processes indicate load control based on the actual load F detected by the load sensor 71. In other words, in the comparative example corresponding to the prior art described in Patent Document 1, load control is performed in all of the first to fourth processes.

[0048] However, since the load sensor 71 generally has low accuracy, in the comparative example, it is necessary to change the braking force corresponding to an offset value dF that exceeds the resolution of the load sensor 71 during excessive operation. As a result, the discrepancy between the required braking force and the holding braking force becomes large, which may lead to a deterioration in the brake feel. In addition, if deformation of the pad 87 or disc 88 occurs due to temperature changes, a phenomenon may occur where the operating point does not change even though the load is changing. In that case, the effect of reducing the drive current of the motor 60 may not be sufficiently obtained.

[0049] Therefore, the applicant previously filed a patent application for a technology that, when maintaining braking force, reduces the deviation from the required braking force by using a "hysteresis-based current reduction process" to ensure a reduction in motor drive current. However, the "hysteresis-based current reduction process" used in combination in this embodiment is not necessarily limited to the configurations that require position control or the configurations that require over-operation and return operation as specified in this patent application.

[0050] Furthermore, during the holding operation, the braking force is maintained, which requires "lock current flow" where the motor is energized while its rotation is stopped. This can lead to current concentration in specific phases and uneven heat generation. As a result, it can cause failures in inverter elements or motor windings, or necessitate the use of highly heat-resistant components.

[0051] Therefore, the applicant previously filed a patent application for a technology that prevents heat generation from being unevenly distributed to a specific phase by performing a "stop position adjustment process" when a multiphase motor is energized in a locked state. Furthermore, the applicant previously filed a patent application for a technology that prevents heat generation from being unevenly distributed to a specific phase by performing a "phase adjustment process" when a multiphase motor is energized in a locked state.

[0052] In this embodiment, the braking force control unit 400 executes a series of processes by combining two or three of the following basic processes: hysteresis-utilizing current reduction processing, stop position adjustment processing, and phase adjustment processing. The definitions of each basic process are as follows.

[0053] "A process that reduces the motor's drive current and torque from the positive efficiency line to the negative efficiency line based on hysteresis characteristics while maintaining braking force through position control or load control" is defined as "hysteresis-based current reduction processing."

[0054] "In lock energization, where the rotation of the motor 60 is stopped while maintaining braking force, the process of adjusting the rotation stop position by position control so as to decrease or increase the absolute value of the current of any phase of interest" is defined as "stop position adjustment process."

[0055] "In lock energization, the current command value Id is set according to the time so that energization at the same current phase is not continued for a predetermined time or longer." * , IQ * The process of changing the phase is defined as the "phase adjustment process".

[0056] Furthermore, a configuration in which the electric brakes 81-84 are equipped with a load sensor 71 in addition to the position sensor 72, and the torque command calculation unit 40 can switch between load control and position control, is designated as "Type A". A configuration in which the electric brakes 81-84 are equipped with only the position sensor 72, and the torque command calculation unit 40 performs only position control, is designated as "Type B". Figure 5 shows the schematic configuration of Type A, and Figure 6 shows the schematic configuration of Type B. For configurations specific to each basic process, refer to the corresponding block diagrams in the descriptions of each basic process described later.

[0057] Figure 5 shows a schematic block diagram of the A-type braking force control unit 400A. The torque command calculation unit 40A includes a load command calculation unit 41, a load controller 43, a position command calculation unit 44, a position controller 46, a holding determination / control switching unit 47, and a switch 48. In Figure 5, for space reasons, the load controller 43 is shown to include a load deviation calculator, and the position controller 46 is shown to include a position deviation calculator.

[0058] The load command calculation unit 41 calculates the load command value F based on the required braking force. * The load controller 43 calculates the actual load F detected by the load sensor 71 and the load command value F. * The load deviation ΔF(=F * -F) should be brought as close to zero as possible, that is, the actual load F should be the load command value F * The torque command value Trq should be brought as close as possible to this value. * Perform "load control" to calculate (f).

[0059] The position command calculation unit 44 calculates the required braking force, actual position θ, and torque command value Trq. * Based on the position command value θ * The position controller 46 calculates the actual position θ detected by the position sensor 72 and the position command value θ. * The positional deviation Δθ(=θ) *To bring -θ) closer to zero, that is, to the actual position θ, the position command value θ * The torque command value Trq should be brought as close as possible to this value. * Perform "position control" by calculating (θ).

[0060] The holding judgment / control switching unit 47 receives the load command value F. * The load deviation ΔF and position deviation Δθ are input. The holding judgment / control switching unit 47 determines the transition to the holding operation and switches the control related to the torque command calculation. In type A, "control switching" includes both the switching between load control and position control, and the switching of processing. The control switching result by the holding judgment and control switching unit 47 is output to the load command calculation unit 41, the position command calculation unit 44, the switch 48, and the current command calculation unit 50. The switch 48 outputs the torque command value Trq from the torque command calculation unit 40A according to the control switching result by the holding judgment and control switching unit 47. * Trq * (f) or Trq * (θ) is switched. In this way, the A-type torque command calculation unit 40A can switch between load control and position control.

[0061] The braking force control unit 400A includes a current command value calculation unit 50 and an inverter (indicated as "INV" in the figure) 55, as well as a current feedback (indicated as "FB" in the figure) control unit 53, which is omitted in Figure 2. Specifically, the current command value calculation unit 50 calculates the dq axis current command value Id by vector control as the current command value. * , IQ * The current feedback control unit 53 calculates the current and outputs it to the current feedback control unit 53. The current feedback control unit 53 acquires the three-phase currents Iu, Iv, and Iw detected by the current sensor 57, and the motor electrical angle, i.e., the actual position θ, detected by the position sensor 72, and converts the three-phase currents Iu, Iv, and Iw into dq-axis currents Id and Iq. The current feedback control unit 53 converts the dq-axis currents Id and Iq into current command values ​​Id * , IQ * The voltage command value is calculated to follow the signal, and a switching signal is generated using PWM control or the like and output to the inverter 55.

[0062] Figure 6 shows a schematic block diagram of the Type B braking force control unit 400B. The Type B torque command calculation unit 40B is equivalent to the Type A torque command calculation unit 40A with the load control configuration removed, and performs only position control. The Type B holding judgment / control switching unit 47 receives the position deviation Δθ as input. In Type B, "control switching" means switching the process. The control switching result by the holding judgment and control switching unit 47 is output to the position command calculation unit 44 and the current command calculation unit 50.

[0063] (Implementations of Group 1 and Group 2) Referring to Figures 7 to 10, an overview of the braking force holding operation according to the first and second group embodiments will be described. In the first and second group embodiments, the braking force control unit 400 performs hysteresis-utilizing current reduction processing and stop position adjustment processing as a series of processes, and then performs phase adjustment processing. In Figures 7 and 9, the phase adjustment processing block shown by the dashed line is assumed to exist. The order in which the stop position adjustment processing and the hysteresis-utilizing current reduction processing are performed differs between the first and second group embodiments.

[0064] If the operating point is moved to the inverse efficiency line by the hysteresis-utilizing current reduction process, and then the braking force is increased by the stop position adjustment process, the operating point will move back to the positive efficiency line, and the maximum current reduction effect will not be obtained. Therefore, in the first embodiment, the above phenomenon is avoided by performing the hysteresis-utilizing current reduction process after performing the stop position adjustment process. In the second embodiment, the above phenomenon is avoided by performing the stop position adjustment process after the excessive operation of the hysteresis-utilizing current reduction process, so as to serve as a return operation, by adjusting the motor's rotation stop position in the direction of decreasing braking force.

[0065] Figure 7 shows an overall scheme diagram of the braking force holding operation according to the first embodiment. In the first embodiment, the braking force control unit 400 performs a stop position adjustment process, and then proceeds to a hysteresis-utilizing current reduction process at the rotation stop position of the motor 60 after adjustment. When the configuration of type A braking force control unit 400A is used, position control is performed until the hysteresis-utilizing current reduction process is over-operated, and load control is performed after the return operation. When the configuration of type B braking force control unit 400B is used, position control continues after the hysteresis-utilizing current reduction process is over-operated and after the return operation.

[0066] When the actual braking force reaches the required braking force during the increasing operation on the positive efficiency line, a holding judgment triggers a transition to a braking force holding operation, where a stop position adjustment process is first performed by position control on the positive efficiency line. Once the stop position adjustment process is complete, the actual load F at completion is stored as the target load, and the system transitions to an over-operation of the hysteresis-utilizing current reduction process. After the over-operation, the system switches to load control, or while continuing position control, transitions to a return operation of the hysteresis-utilizing current reduction process, where a return operation is performed on the inverse efficiency line to the stored target load. At this time, it is preferable to set a dead zone so that the operating point does not return to the positive efficiency line side.

[0067] The braking force control unit 400 performs a hysteresis-based current reduction process following the stop position adjustment process, and then performs a phase adjustment process. The phase adjustment process continues until the holding state ends. The appropriate adjustment direction and amount in the phase adjustment control vary depending on the motor's rotation stop position and output torque. Therefore, it is efficient and effective to perform the phase adjustment process after the motor's position and torque have finished changing due to the stop position adjustment process or the hysteresis-based current reduction process.

[0068] The overall scheme in Figure 7 assumes that the required braking force is constant, and does not anticipate a sudden change in the required braking force during a series of processes. In reality, if the required braking force changes suddenly during the hysteresis-based current reduction process or the stop position adjustment process, the process is interrupted, the holding operation is released, and the system transitions to an increasing or decreasing operation. Also, if the required braking force changes suddenly while the phase adjustment process is being executed, the phase adjustment process is terminated, and the system transitions to an increasing or decreasing operation.

[0069] Figure 8(a) shows the flowchart for determining the transition from stop position adjustment processing to hysteresis-based current reduction processing, and Figure 8(b) shows the flowchart for determining the transition from hysteresis-based current reduction processing to phase adjustment processing. In the following flowchart explanation, the symbol "S" means step. In Figure 8(a), at S011, stop position adjustment processing is being performed. If it is determined at S012 that the absolute value of the position deviation |Δθ| is smaller than the position deviation threshold Δθth01, then at S013, the process transitions to hysteresis-based current reduction processing. In Figure 8(b), at S021, hysteresis-based current reduction processing is being performed. In the case of configuration A, if it is determined at S022 that the absolute value of the load deviation |ΔF| is smaller than the load deviation threshold ΔFth02, then at S023, the process transitions to phase adjustment processing.

[0070] To prevent misjudgments in S012 and S022, it is preferable that the determination is made as YES not when the condition is met instantaneously, but when the condition remains met for a predetermined period of time. Furthermore, the hysteresis-based current reduction process is not limited to a method that temporarily exceeds the limit and then returns to normal; a method that does not involve a change in position (for example, a method that reduces the current by a predetermined amount) may also be adopted. In that case, the completion of the hysteresis-based current reduction process becomes the condition for determining the transition to the phase adjustment process.

[0071] In the first embodiment, the combination with the hysteresis-utilizing current reduction process eliminates constraints on the position adjustment direction during the stop position adjustment process. Therefore, the effect of preventing uneven heat generation to a specific phase can be obtained with a smaller adjustment range. As a modification of the first embodiment, a part of the hysteresis-utilizing current reduction process may be started in advance before the execution of the stop position adjustment process.

[0072] Figure 9 shows an overall scheme diagram of the braking force holding operation according to the second embodiment. In the second embodiment, the braking force control unit 400 performs an over-operation of the hysteresis-utilizing current reduction process, and then, while also performing a return operation of the hysteresis-utilizing current reduction process, performs a stop position adjustment process to adjust the rotation stop position of the motor 60 in the direction of decreasing braking force. In the second embodiment, a configuration of type B braking force control unit 400B is used.

[0073] When the actual braking force reaches the required braking force during the increasing operation on the positive efficiency line, the system transitions to a braking force holding operation based on a holding determination. When the required braking force is constant, an over-operation of the hysteresis-utilizing current reduction process is performed on the positive efficiency line, and the actual load F at the completion of the over-operation is stored as the target load. Subsequently, a stop position adjustment process is performed, which also serves as a return operation for the hysteresis-utilizing current reduction process, limiting the position adjustment direction to the braking force reduction direction and setting the target adjustment position to a location near the position corresponding to the target load. At this time, it is preferable to set a dead zone so that the operating point does not return to the positive efficiency line side. After performing the return operation of the hysteresis-utilizing current reduction process and the stop position adjustment process, the braking force control unit 400 further performs a phase adjustment process. The reason why it is better to perform the phase adjustment process later, and the release of the holding operation, are the same as in the first embodiment.

[0074] Figure 10 shows a flowchart for determining the transition from the return operation and stop position adjustment process of the hysteresis-utilizing current reduction process to the phase adjustment process. In S031, the return operation and stop position adjustment process of the hysteresis-utilizing current reduction process is executed. If in S032 it is determined that the absolute value of the position deviation |Δθ| is smaller than the position deviation threshold Δθth03, the process transitions to the phase adjustment process in S033. To prevent misjudgment in S032, it is preferable that the judgment is not made as YES when the condition is met instantaneously, but rather when the condition remains met for a predetermined period of time.

[0075] In the second embodiment, the return operation of the hysteresis-utilizing current reduction process and the stop position adjustment process can be executed simultaneously, thereby suppressing the ups and downs of the actual braking force during the braking force holding operation. In addition, the time required to converge to the final braking force holding value can be shortened, and the effect of phase adjustment can be obtained more quickly.

[0076] In the first and second embodiment, the combination of hysteresis-utilizing current reduction processing and stop position adjustment processing, and the combination of hysteresis-utilizing current reduction processing and phase adjustment processing, can obtain both the effect of reducing current during braking force maintenance and the effect of preventing uneven heat generation to a specific phase.

[0077] Furthermore, regarding the combination of stop position adjustment processing and phase adjustment processing, in the stop position adjustment processing, the range in which position adjustment is possible may be limited by the allowable range of fluctuations in the required load. In such cases, by using phase adjustment processing in combination, it is possible to prevent uneven heat generation to a specific phase.

[0078] (Implementations of Group 3 and Group 4) The third embodiment is defined as one in which the phase adjustment process is not performed compared to the first embodiment, and the fourth embodiment is defined as one in which the phase adjustment process is not performed compared to the second embodiment. In the third and fourth embodiments, the phase adjustment process blocks shown by dashed lines in Figures 7 and 9 are considered to be absent. By having the braking force control unit 400 perform the hysteresis-utilizing current reduction process and the stop position adjustment process as a series of processes, both the effect of reducing the current when maintaining the braking force and the effect of preventing uneven heat generation to a specific phase can be obtained.

[0079] (Group 5 Embodiment) Figure 11 shows an overall scheme diagram of the braking force holding operation according to the fifth embodiment. When the braking force is held, the braking force control unit 400 performs a hysteresis-utilizing current reduction process, followed by a phase adjustment process. The stop position adjustment process is not performed. The braking force control unit 400 may, similar to the first embodiment, perform an over-operation of the hysteresis-utilizing current reduction process by position control, then switch to load control, or continue position control while performing the return operation and phase adjustment process. Alternatively, the braking force control unit 400 may perform everything from the over-operation to the phase adjustment process by load control. In other words, it is not a requirement that the electric brakes 81-84 are equipped with position sensors or that the torque command calculation unit 40 performs position control. As the hysteresis-utilizing current reduction process, the configuration of the comparative example shown in Figure 4 may be used, not limited to the H1-H3 embodiments. In the fifth embodiment, both the current reduction effect during braking force holding and the effect of preventing uneven heat generation to a specific phase can be obtained.

[0080] (Group 6 Embodiment) Figure 12 shows an overall scheme diagram of the braking force holding operation according to the sixth embodiment. When the braking force is held, the braking force control unit 400 performs a stop position adjustment process, followed by a phase adjustment process. Hysteresis-based current reduction processing is not performed. The electric brakes 81-84 are equipped with position sensors 72, and the torque command calculation unit 40 performs at least position control. For example, when holding from an increasing operation, the operating point changes only on the positive efficiency line. The effect of the combination of the stop position adjustment process and the phase adjustment process is as described above in the first and second embodiment.

[0081] In summary, the embodiments of the first to sixth groups described above can be described as follows: In this embodiment, when hysteresis-utilizing current reduction processing, stop position adjustment processing, or phase adjustment processing are combined, the reduction in effectiveness due to interference between the controls can be appropriately avoided, and the braking force holding operation can be performed efficiently and effectively.

[0082] Next, we will explain in detail each of the basic processes: hysteresis-based current reduction processing, stop position adjustment processing, and phase adjustment processing. For distinction, embodiments of hysteresis-based current reduction processing will be denoted with the letter "H" derived from 'hysteresis', embodiments of stop position adjustment processing will be denoted with the letter "L" derived from 'lock', and embodiments of phase adjustment processing will be denoted with the letter "P" derived from 'phase'.

[0083] [Current reduction processing utilizing hysteresis] Referring to Figures 13 to 20, embodiments H1 to H3 of the hysteresis-utilizing current reduction process will be described. In each embodiment of H1 to H3, when the torque command calculation unit 40 increases the actual braking force to the required braking force and holds it, it changes the torque command value in the order of the first process, second process, third process, and fourth process shown in Figure 4. The torque command calculation unit 40 calculates the torque command value by position control based on the actual position θ detected by the position sensor 72, at least in the second process.

[0084] Next, the detailed configuration for each embodiment will be described. The torque command calculation units of embodiments H1 and H2, which correspond to the configuration of type A, are denoted as "401H" to distinguish them, and the torque command calculation unit of embodiment H3, which corresponds to the configuration of type B, is denoted as "403H" to distinguish them. In the first and third group embodiments, any of embodiments H1 to H3 may be adopted. In the second and fourth group embodiments, embodiments H2 or H3, in which position control is performed in the return operation of the fourth process, are adopted. In the fifth group embodiment, not limited to embodiments H1 to H3, the configuration of the comparative example shown in Figure 4, in which only load control is performed, may be adopted.

[0085] (H1, H2 embodiments) The H1 and H2 embodiments will be described with reference to Figures 13 to 16. In the H1 and H2 embodiments, as the transitions from the first to the fourth processes occur, load control based on the actual load F detected by the load sensor 71 and position control based on the actual position θ detected by the position sensor 72 are switched.

[0086] Figure 13 shows a block diagram of the torque command calculation unit 401H in the H1 and H2 embodiments. The torque command calculation unit 401H includes a load command calculation unit 41, a load deviation calculator 42, a load controller 43, a position command calculation unit 44, a position deviation calculator 45, a position controller 46, a switching determination unit 47, and a switch 48.

[0087] The load command calculation unit 41 calculates the load command value F based on the required braking force. * The load deviation calculator 42 calculates the actual load F detected by the load sensor 71 and the load command value F. * The load deviation ΔF(=F * The load controller 43 calculates -F). The load controller 43 adjusts the load deviation ΔF to approach zero, that is, the actual load F to the load command value F. * The torque command value Trq should be brought as close as possible to this value. * Perform the operation (f).

[0088] The position command calculation unit 44 calculates the position command value θ based on the required braking force, either by the method described later or as shown by the dashed line. * The calculation is performed using the actual position θ detected by the position deviation calculator 45 and position sensor 72, and the position command value θ. * The positional deviation Δθ(=θ) * The position controller 46 calculates the position deviation Δθ to zero, i.e., the actual position θ to the position command value θ. * The torque command value Trq should be brought as close as possible to this value. * Calculate (θ).

[0089] The switching determination unit 47 determines the torque command value Trq of the motor 60 according to each of the processes from the first to the fourth process. * The configuration for performing the calculation determines whether to switch between load control by the load controller 43 and position control by the position controller 46.

[0090] The switching determination unit 47 receives the load command value F. * The load deviation ΔF and, depending on the embodiment, the position deviation Δθ are input. Load command value F * This allows for the understanding of fluctuations in the required braking force. Load command value F *When the amount of variation is within a predetermined range, and the load deviation ΔF is below the load deviation threshold, the actual load F in load control is equal to the load command value F * It is determined that the position has reached this point. Also, when the position deviation Δθ falls below the position deviation threshold, the actual position θ in position control becomes the position command value θ * It is determined that the goal has been reached.

[0091] The switch 48 receives a command from the switching determination unit 47, and the torque command calculation unit 401H outputs a torque command value Trq * The switch is toggled. In the configuration example shown in Figure 13, a switch 48 is provided on the output side of each controller 43, 46, but the configuration is not limited to this, and the switching function may be implemented to mask the operation of either the load controller 43 or the position controller 46, for example.

[0092] Furthermore, the timing of the transition from the first process to the second process is referred to as the "over-operation start timing." The load command calculation unit 41 converts the actual position θ obtained at the over-operation start timing notified by the switch 48 into a position command value θ * The calculation may be performed in this manner. This position command value θ * This becomes the initial position command value in the second stage of position control. For details, please refer to the flowchart in Figure 20, which will be explained later.

[0093] Figure 14 shows the switching between load control and position control according to the H1 embodiment. The hysteresis characteristics of torque and braking force are the same as those of the comparative example shown in Figure 4. As shown by the double vertical axis, in the H1 and H2 embodiments, the braking force correlates with load F and position θ. In other words, load F and position θ are used in a dual manner as parameters correlated with the braking force.

[0094] The load F corresponding to the required braking force becomes the target holding load Fhold, and the position θ corresponding to the required braking force becomes the target holding position θhold. Furthermore, the load F corresponding to the target excess braking force becomes the target excess load Fex (=Fhold+dF), which is greater than the target holding load Fhold by an excess amount dF. The position θ corresponding to the target excess braking force becomes the target excess position θex (=θhold+dθ), which is greater than the target holding position θhold by an excess amount dθ. Here, the magnitude of the position θ is defined according to the magnitude of the corresponding braking force. In other words, the larger the corresponding braking force, the larger the position θ.

[0095] In Figures 14 to 16, the white block arrows represent load control, and the hatched block arrows represent position control. In both the H1 and H2 embodiments, the torque command calculation unit 401H performs load control in the first process. In the H1 embodiment, the torque command calculation unit 401H performs position control in the second process and load control in the third and fourth processes. When the torque command calculation unit 401H transitions from the first process to the second process, the switching determination unit 47 switches from load control to position control.

[0096] In detail, when transitioning from the first process to the second process, the switching determination unit 47 commands the switch 48 to switch to position control if the load deviation ΔF falls below the load deviation threshold. The torque command calculation unit 401H stores the actual load F detected by the load sensor 71 as the target holding load Fhold at the start timing of the over-operation transition from the first process to the second process. In the second process, the actual position θ is set to the position command value θ * The torque command value calculated by the position controller 46 to approximate this value is used.

[0097] Furthermore, when transitioning from the second to the third process, the switching determination unit 47 commands the switch 48 to switch to load control if the position deviation Δθ falls below the position deviation threshold. In the third process, no active control is performed, and the torque decreases naturally from the positive efficiency line to the negative efficiency line. When the torque command value decreases to the negative efficiency line, the system transitions to the fourth process while remaining in load control mode. In the fourth process, the torque command calculation unit 401H continues the return operation until the actual load F reaches the target holding load Fhold.

[0098] In the H1 embodiment, a high-precision position sensor 72 is used in the excess operation of the second process, and position control can be performed by setting the position excess amount dθ to be as small as possible according to the resolution of the position sensor 72. Therefore, compared to the comparative example in which load control is performed in the second process, the discrepancy between the actual braking force and the required braking force in the holding operation can be reduced, and deterioration of the feeling can be prevented. Furthermore, even if load changes occur due to temperature changes, the motor drive current can be reduced until the operating point changes reliably by directly detecting the position of the motor 60 and the linear motion mechanism 85 with the position sensor 72.

[0099] Furthermore, since the existing electric brakes 81-84 are equipped with load sensors 71, the torque command calculation unit 401H can switch the control so that position control is performed only in the second process, and load control is performed in the first, third, and fourth processes, thereby minimizing changes from the existing design. In addition, by using the same control for the third and fourth processes, the transition from the holding operation to the return operation can be performed automatically without having to determine the end of the holding operation.

[0100] Figure 15 shows the switching between load control and position control according to a modified example of the H1 embodiment. In this modified example, the torque command calculation unit 401H performs position control in the third process following the second process, and then performs load control in the fourth process. In other words, the switch from position control to load control occurs not at the timing of transitioning from overdrive to holding, but at the timing of transitioning from holding to return. In this modified example, it is necessary to add logic for the switching determination unit 47 to determine the end of the holding operation, but the same effects as in the H1 embodiment can be obtained by performing position control in the second process.

[0101] Figure 16 shows the switching between load control and position control according to the H2 embodiment. In the H2 embodiment, the torque command calculation unit 401H performs position control in the third and fourth processes following the second process. Similar to the H1 embodiment, when the torque command calculation unit 401H transitions from the first process to the second process, the switching determination unit 47 switches from load control to position control.

[0102] The torque command calculation unit 401H stores the actual position θ detected by the position sensor 72 as the target holding position θhold at the start timing of the over-operation transition from the first process to the second process. In the second process, the actual position θ is converted to the position command value θ. * The torque command value calculated by the position controller 46 to approximate this value is used.

[0103] When the actual position θ reaches the target over-position θex, the process transitions from the second to the third process, and the torque decreases from the positive efficiency line to the negative efficiency line while the braking force at the end of the over-operation is maintained. When the torque command value decreases to the negative efficiency line, the process transitions to the fourth process while maintaining position control. In the fourth process, the torque command calculation unit 401H continues the return operation until the actual position θ reaches the target holding position θhold.

[0104] In the H2 embodiment, the same effects as in the H1 embodiment can be obtained by performing position control in the second process. Furthermore, position control can be performed with the same accuracy in both the overshoot and return operations for minute position overshoots dθ.

[0105] (H3 embodiment) The H3 embodiment will be described with reference to Figures 17 and 18. In the H3 embodiment, the torque command calculation unit 403H performs position control based on the actual position θ detected by the position sensor 72 in all of the first to fourth processes. Figure 17 shows a block diagram of the torque command calculation unit 403H of the H3 embodiment. The torque command calculation unit 403H includes a position command calculation unit 44, a position deviation calculator 45, and a position controller 46.

[0106] The position command calculation unit 44 calculates the position command value θ based on the requested braking force. * The calculation is performed. In the configuration of Figure 13, the required braking force is basically input to the load command calculation unit 41, but it may also be input to the position command calculation unit 44. In contrast, in the configuration of Figure 17, there is no load command calculation unit 41, so the required braking force is always input to the position command calculation unit 44. The position deviation calculator 45 and the position controller 46 are the same as in the configuration of Figure 13, so their explanation is omitted.

[0107] The position deviation Δθ(=θ) calculated by the position deviation calculator 45 * -θ) is fed back to the position command calculation unit 44. When the position deviation Δθ falls below the position deviation threshold, the position command calculation unit 44 determines that the actual position θ in position control is equal to the position command value θ. * We determine that we have reached this point.

[0108] Figure 18 shows braking force control by position control according to the H3 embodiment. The hysteresis characteristics of torque and braking force are the same as in the comparative example and the H1 and H2 embodiments. In the H3 embodiment, the braking force correlates only with position θ. In Figure 18, hatched block arrows represent position control. The torque command calculation unit 403H performs position control in the first process.

[0109] The torque command calculation unit 403H calculates the position command value θ, which corresponds to the required braking force, based on the actual position θ. * Upon reaching this point, the actual position θ detected by the position sensor 72 at the start of the over-operation that transitions from the first process to the second process is stored as the target holding position θhold. Thereafter, position control continues up to the fourth process, similar to the H2 embodiment.

[0110] In the H3 embodiment, the same effects as in the H1 and H2 embodiments can be obtained by performing position control in the second process. Furthermore, since logic for switching between load control and position control is not required, the configuration of the torque command calculation unit 403H is simplified.

[0111] [Flowchart for braking force control using hysteresis-based current reduction processing] Next, referring to the flowcharts in Figures 19 and 20, we will explain the braking force control in the hysteresis-utilizing current reduction process, encompassing embodiments H1 to H3.

[0112] Figure 19 shows the flow of operation switching when the required braking force increases. This flow applies to the H1 and H2 embodiments, where load control is performed in the first process. Considering the situations in which the H1 and H2 embodiments are effectively used, the case of a decrease in the required braking force is omitted from the premise. Therefore, the logic for determining whether the required braking force is increasing or decreasing is also omitted. However, in actual system design, it is necessary to design the flow to include the case where the required braking force decreases.

[0113] In S11H, it is determined whether the first process (increase operation) is in progress. If the answer in S11H is YES, the actual braking force increases in S12H. In S13H, it is determined whether the load deviation ΔF is smaller than the load deviation threshold ΔFth1. If the answer in S13H is YES, in S14H, the system switches to the third process (holding operation) after going through the second process (over-operation).

[0114] If NO is given in S11H, it is presumed that the third process (holding operation) is in progress. In embodiments H1 and H2, it is not assumed that the required braking force will change abruptly during the third process, but in reality, the required braking force will change abruptly during the third process, and the load command value F will change accordingly. * The load command value F may change suddenly. Excluding the case of a sudden decrease, given the premise of an increase in required braking force, the load command value F * The actual load F and the load command value F increased sharply. *A sudden increase in the load deviation ΔF is anticipated. In S15H, it is determined whether the load deviation ΔF is greater than the load deviation threshold ΔFth2. If the answer in S15H is YES, in S16H, the third process (holding operation) is canceled and the system switches to the first process (increasing operation).

[0115] Figure 20 shows the flow of position command calculation by the position command calculation unit 44. In S21H, the first process (increase operation) is performed. In S22H, it is determined whether the actual braking force has reached the required braking force and whether the process has moved from the first process to the second process. If the answer in S22H is YES, in S23H, the actual position θ at the start of the excess operation is stored as the target holding position θhold.

[0116] In S24H, during the second process (over-operation), the position command value θ * Position control is performed by sequentially increasing the value θ. Specifically, a provisional position θtemp greater than the target holding position θhold is set to the position command value θ. * The provisional position θtemp is increased prior to the increase in the actual position θ. This increases the provisional position θtemp (i.e., the position command value θ). * The actual position θ increases in accordance with the increase in ).

[0117] In S25H, it is determined whether the provisional position θtemp has reached the target overshoot position θex. If the answer in S25H is YES, the process moves to the third stage (holding operation) in S26H. After S26H, two patterns of steps, S27H or S28H, can be selected.

[0118] In S27H, which corresponds to the H1 embodiment, the load control is switched to the fourth process (return operation) and the load command value F * This is set to the target holding load Fhold. In S28H, which corresponds to the H2 and H3 embodiments, the position command value θ of the fourth process (return operation) remains the same as the position control. * The target holding position θhold is changed.

[0119] [Stop position adjustment process] The configurations of the L1 and L2 embodiments relating to the stop position adjustment process will now be described. In the specification and drawings of this part, "this embodiment" refers to an embodiment of the stop position adjustment process. The braking force control units of the L1 and L2 embodiments differ only in the control configuration of the part that switches between executing and not executing the stop position adjustment process, but the effect is the same. The torque command calculation unit that includes the part that switches between executing and not executing the stop position adjustment process is denoted as "401L" for the torque command calculation unit of the L1 embodiment and as "402L" for the torque command calculation unit of the L2 embodiment to distinguish them.

[0120] (L1 embodiment) The L1 embodiment will be described with reference to Figures 21 to 31. In the L1 embodiment, when the stop position adjustment process is performed, the actual position θ is set to the position command value θ. * If position control is performed to follow the target and no stop position adjustment process is performed, the actual load F will be the load command value F. * Load control is performed to follow the movement. Load control is performed during the process in which the braking force increases along the positive efficiency line and decreases along the negative efficiency line. During the process of reducing torque while maintaining the braking force, position control is performed to adjust the stopping position as needed. Note that the stopping position adjustment process may be effectively stopped by setting the adjustment amount to zero.

[0121] Figure 21 shows a block diagram of the braking force control unit 400L of the L1 embodiment corresponding to the configuration of type A. The torque command calculation unit 401L includes a load command calculation unit 41, a load deviation calculator 42, a load controller 43, a position deviation calculator 45, a position controller 46, and a switch 48.

[0122] The load command calculation unit 41 calculates the load command value F based on the required braking force. * The load deviation calculator 42 calculates the actual load F detected by the load sensor 71 and the load command value F. * The load deviation ΔF(=F * The load controller 43 calculates -F). The load controller 43 adjusts the load deviation ΔF to approach zero, that is, the actual load F to the load command value F. * The torque command value Trq should be brought as close as possible to this value.* Perform the operation (f).

[0123] The position deviation calculator 45 uses the actual position θ detected by the position sensor 72 and the position command value θ output by the stop position adjuster 67. * The positional deviation Δθ(=θ) * The position controller 46 calculates the position deviation Δθ to zero, i.e., the actual position θ to the position command value θ. * The torque command value Trq should be brought as close as possible to this value. * Calculate (θ).

[0124] The switch 48, in accordance with the switching signal from the stop position adjuster 67, outputs the torque command value Trq from the torque command calculation unit 401L. * Trq * (f) or Trq * Switching (θ). In the configuration example shown in Figure 21, a switch 48 is provided on the output side of each controller 43, 46, but the configuration is not limited to this, and the switching function may be implemented to mask the operation of either the load controller 43 or the position controller 46, for example.

[0125] Furthermore, the braking force control unit 400L includes, in addition to the current command value calculation unit 50 and the inverter (indicated as "INV" in the figure) 55, a current feedback (indicated as "FB" in the figure) control unit 53, a lock energization determination unit 69, and a stop position adjuster 67, which are omitted in Figure 2.

[0126] The current command value calculation unit 50 calculates the current command value Id * , IQ * The current feedback control unit 53 calculates the current and outputs it to the current feedback control unit 53. The current feedback control unit 53 acquires the three-phase currents Iu, Iv, and Iw detected by the current sensor 57, and the motor electrical angle, i.e., the actual position θ, detected by the position sensor 72, and converts the three-phase currents Iu, Iv, and Iw into dq-axis currents Id and Iq. The current feedback control unit 53 converts the dq-axis currents Id and Iq into current command values ​​Id * , IQ * The voltage command value is calculated to follow the signal, and a switching signal is generated using PWM control or the like and output to the inverter 55.

[0127] The lock energization determination unit 69 determines whether the motor 60 is in a "locked energized" state, where it is energized while the rotation of the motor 60 has stopped, based on the fluctuation range and time derivative of the actual position θ. When it determines that the motor is in a locked energized state, it outputs a lock energization signal to the stop position adjuster 67. Note that "stopped" rotation includes, for example, an ultra-low rotation state of a few rpm.

[0128] The stop position adjuster 67 obtains the load torque TL1-TL4 and motor temperature Temp1-Temp4 from the corresponding electric brakes 81-84 and determines whether the exemption requirements described later are met. Unless the exemption requirements are met, the stop position adjuster 67 performs a "stop position adjustment process" to adjust the rotation stop position within a predetermined position adjustment range when the lock is energized. In the following specification, "stop position" means the rotation stop position.

[0129] This embodiment is applied to an electric brake device in which the load acting on the load changes according to the rotational stop position of the motor 60 when the lock is energized. Next, referring to Figures 22 to 29, the technical significance of the stop position adjustment process will be explained in comparison with a comparative example in which the stop position adjustment process is not performed when the lock is energized.

[0130] According to the definition of the stop position adjustment process, the stop position adjuster 67 adjusts the rotation stop position by position control so as to decrease or increase the absolute value of the current of any of the phases of interest when the lock is energized. Specifically, the following two examples are considered: [1] The stop position adjuster 67 adjusts the rotation stop position so as to reduce the absolute value of the current of the maximum current phase, which has the highest absolute value of current among the phases. [2] The stop position adjuster 67 adjusts the rotation stop position so as to bias the current towards one or more high heat dissipation phases, which have relatively high heat dissipation among the phases.

[0131] Figure 22 shows the stopping position for the required load in the comparative example. In the comparative example, the stopping position is uniquely determined once the required load, which is the target value of the load acting on the load, is determined, and it is possible to stop at a position where current is concentrated in a specific phase. Figure 23 shows example 1 of the lock energization position in the comparative example. The phase with the maximum absolute value of current among each phase is defined as the "maximum current phase". In the example in Figure 23, the absolute value of the V-phase current Iv is maximum at the lock energization position, and the V-phase corresponds to the maximum current phase.

[0132] Figure 24 shows the stopping position for the required load in this embodiment. In the stopping position adjustment process, the rotational stopping position of the motor 60 is adjusted to a range corresponding to the allowable range of variation of the required load. In Figure 24, the load change due to the position adjustment is represented as ΔF. The direction of position adjustment is defined, for example, as positive when the load increases and negative when the load decreases. Figure 24 shows that the adjustment of position θ and the adjustment of load F are correlated with each other.

[0133] Figure 25 shows an example 1 of the lock energization position in this embodiment. In this example, the stop position is adjusted from the position before adjustment to a position where the signs of the V-phase current Iv and the U-phase current Iu are opposite and their absolute values ​​are equal. Figure 26 shows the phase currents when the lock energization is applied. In the comparative example, the state before adjustment continues, and heat generation is uneven in the elements of the inverter 55 and the windings of the motor 60, which are the phases with the maximum current. In contrast, in the stop position adjustment process of this embodiment, the stop position is adjusted to reduce the absolute value of the current of the V-phase, which is the phase with the maximum current. Preferably, the position where the absolute value of the current of the phase with the maximum current is minimized (for example, the position with an electrical angle of 45° where the absolute values ​​of the V-phase current Iv and the U-phase current Iu are equal) becomes the target position θtgt of the stop position adjustment process. The torque command calculation unit 401L calculates the torque command value Trq which reflects the adjusted rotation stop position. * Perform the calculation.

[0134] Figure 27 shows example 2 of the lock current position for the required load in the comparative example. The phase with relatively high heat dissipation among the phases is defined as the "high heat dissipation phase". In the example in Figure 27, it is assumed that the U phase is the high heat dissipation phase, and the lock current is applied at the position where the absolute value of the W phase current Iw is maximum (the position of electrical angle 135°).

[0135] Figure 28 shows an example 2 of the lock energization position in this embodiment. In this example, the stopping position is adjusted by 60° of electrical angle from the position of 135° of electrical angle before adjustment to the position of 75° of electrical angle where the absolute value of the current of the U-phase, which is the high heat dissipation phase, is maximum. In other words, when there is one high heat dissipation phase, the position where the absolute value of the current of the high heat dissipation phase is maximum becomes the target position θtgt of the stopping position adjustment process.

[0136] At this point, the absolute values ​​of the U-phase current Iu and the W-phase current Iw become equal at an electrical angle of 105°, which is 30° of adjustment from the position before adjustment. Therefore, in the section from an electrical angle of 105° to an electrical angle of 75°, shown by the thick line, the absolute value of the current in the U-phase, which is the high heat dissipation phase, is the largest among the three phases. In other words, the rotation stop position is adjusted to bias the current towards the high heat dissipation phase. In particular, when the rotation stop position is adjusted to an electrical angle of 75°, the absolute value of the current in the high heat dissipation phase is the largest.

[0137] Figure 29 shows the thermal imbalance of each phase in a three-phase motor with a stator having 3 slots spaced 120° apart, as a simple configuration example. In the figure, "Cold" refers to the high-heat-dissipation phase, and "Hot" refers to the low-heat-dissipation phase. The circumferential range corresponding to the high-heat-dissipation phase is shown by a solid double arrow, and the circumferential range corresponding to the low-heat-dissipation phase is shown by a dashed double arrow. If the U phase is the high-heat-dissipation phase and the V and W phases are the low-heat-dissipation phases, then before adjustment when the motor is locked, a large current is supplied to the W phase, which is the low-heat-dissipation phase. In the comparative example, the pre-adjustment state continues, and heat generation is unevenly distributed in the elements of the inverter 55 and the windings of the motor 60, which are the low-heat-dissipation phases. In contrast, in the stop position adjustment process of this embodiment, the stop position is adjusted so that the current is unevenly distributed to the U phase, which is the high-heat-dissipation phase.

[0138] For example, the stop position adjuster 67 may store the relationship between the actual position θ before adjustment and the target position θtgt as a map, or, in the case of a three-phase motor, it may adjust the position so that the remainder when the actual position θ is divided by 60° is a specific value. Alternatively, instead of directly adjusting the position, the stop position adjuster 67 may store a map of the load corresponding to the target position θtgt and adjust the position so that the actual load F falls within an appropriate range.

[0139] In the stop position adjustment process, it is preferable that the rotation stop position of the motor 60 be adjusted to the target position θtgt as in the example above. However, the position adjustment range, which is limited based on the allowable range of variation of the required load, may be smaller than the amount of position change to the target position θtgt. In that case, the rotation stop position of the motor 60 is adjusted to the position closest to the target position θtgt within the position adjustment range.

[0140] Referring to the flowchart in Figure 30, the stop position adjustment process by the stop position adjuster 67 will be explained. In the following flowchart, the symbol "S" represents a step. At S10L, the stop position adjuster 67 determines whether or not the lock energization is active based on the presence or absence of a lock energization signal input. If the result at S10L is YES, at S20L the stop position adjuster 67 determines whether the exemption requirements are met. For specific examples of the exemption requirements, refer to Figure 15.

[0141] If NO is selected in S20L, the stop position adjuster 67 performs the stop position adjustment process within the phase adjustment range in S30L. If NO is selected in S10L, or YES is selected in S20L, the stop position adjuster 67 stops the execution of the stop position adjustment process in S25L. For example, the switch 48 may switch from position control to load control, or the stop position adjuster 67 may set the adjustment amount to zero and perform position control.

[0142] (exempted from application) In this embodiment, the stop position adjuster 67 does not always perform the stop position adjustment process. In situations where heat generation in a specific phase does not become a problem even when the lock is energized, it is not necessary to perform the stop position adjustment process. Therefore, if the predetermined exclusion requirements are met, the stop position adjuster 67 does not perform the stop position adjustment process.

[0143] The flowchart in Figure 31 shows an example of determining whether an exemption requirement is met. In this example, the three requirements are judged sequentially in S21L to S23L. If at least one of S21L to S23L is judged as YES, then in S24L, it is determined that the exemption requirement is met.

[0144] The braking force control unit 400L acquires the load torques TL1-TL4 or motor temperatures Temp1-Temp4 of each motor 60. In S21, it is determined whether the load torques TL1-TL4 of the motors 60 are below a predetermined torque threshold. In the low-load region, the current flowing when the motors are locked is small, so heat generation is not a problem.

[0145] In S22L, it is determined whether the fluctuation of the load torque TL1-TL4 of motor 60 is greater than a predetermined torque fluctuation threshold. If the result in S22L is YES, motor 60 rotates, and therefore the locked state is not achieved. In S23L, it is determined whether the temperature Temp1-Temp4 of motor 60 is below a predetermined temperature threshold. Even if the locked state is achieved, if there is sufficient margin above the allowable upper temperature limit, it is not necessary to perform the stop position adjustment process.

[0146] Thus, if locking does not occur in the first place, or if heat generation in a specific phase does not pose a problem even when locking is performed, the stop position adjuster 67 does not perform the stop position adjustment process. This avoids the unnecessary occurrence of load changes ΔF due to position adjustment.

[0147] (L2 embodiment) Figure 32 shows a block diagram of the braking force control unit 400L of the L2 embodiment, which corresponds to the configuration of type B. Components that are substantially the same as those in the L1 embodiment are denoted by the same reference numerals and their descriptions are omitted. The torque command calculation unit 402L of the L2 embodiment performs position control based on the actual position θ detected by the position sensor 72 throughout the entire process of increasing, holding, and decreasing the braking force. The torque command calculation unit 402L includes a position command calculation unit 44, a position deviation calculator 45, a position controller 46, and a switch 68. The position command calculation unit 44 calculates the basic position command value θ based on the requested braking force. * Perform the operation on 0.

[0148] Similar to the L1 embodiment, the braking force control unit 400L includes a lock energization determination unit 69 and a stop position adjuster 67. When the stop position adjuster 67 determines that it will execute the "stop position adjustment process", it calculates the adjusted position command value θ * a and outputs a switching signal to the switch 68. The switch 68 receives the basic position command value θ * 0 calculated by the position command calculation unit 44, and the adjusted position command value θ * a calculated by the stop position adjuster 67.

[0149] When the switch 68 does not execute the stop position adjustment process, it selects the basic position command value θ * 0, and when it executes the stop position adjustment process, it is switched to select the adjusted position command value θ * a. The position command value θ * selected by the switch 68 is input to the position deviation calculator 45. Since the position deviation calculator 45 and the position controller 46 have the same configuration as that in FIG. 21, the description thereof is omitted.

[0150] In the L2 embodiment, the specific configuration, operation, and effects of the stop position adjustment process are the same as those in the L1 embodiment, and it is possible to prevent heat generation from being biased to a specific phase when the motor 60 is locked and energized.

[0151] [Phase Adjustment Process] The configurations of the P1 - P3 embodiments related to the phase adjustment process will be described. "This embodiment" in the description and drawings of this part refers to the embodiment of the phase adjustment process. FIG. 33 shows a configuration example of the braking force control unit 400P. The braking force control unit 400P includes a torque command calculation unit 40, a current command calculation unit 50, a rotation stop determination unit 52, a current feedback (denoted as "FB" in the figure) control unit 53, and an inverter (denoted as "INV" in the figure) 55. The torque command calculation unit 40 calculates the torque command value Trq * of the motor 60 based on the required braking force. The current command calculation unit 50 calculates the dq - axis current command values Id * and Iq * corresponding to the torque command value Trq * and outputs them to the current feedback control unit 53.

[0152] The current feedback control unit 53 acquires the three-phase currents Iu, Iv, and Iw detected by the current sensor 57, and the motor electrical angle (actual position) θ detected by the position sensor (rotation angle sensor) 72, and converts the three-phase currents Iu, Iv, and Iw into dq-axis currents Id and Iq. The current feedback control unit 53 converts the dq-axis currents Id and Iq into a current command value Id * , IQ * The system calculates a voltage command value to follow the command, and then generates a gate drive signal which is output to the inverter 55.

[0153] The rotation stop determination unit 52 determines that the rotation of the motor 60 has stopped based on the motor electrical angle θ detected by the position sensor 72 and notifies the current command calculation unit 50. Note that "stopping" the rotation includes, for example, an ultra-low rotation state of a few rpm. The rotation stop determination unit 52 corresponds to the "lock energization determination unit 69" in the stop position adjustment process. The current command calculation unit 50 also obtains the load torque TL1-TL4 and motor temperature Temp1-Temp4 from the corresponding electric brakes 81-84 and determines whether the exemption requirements described later have been met.

[0154] The current command calculation unit 50 executes a phase adjustment process when the corresponding three-phase motor 60 does not meet the exemption requirements and the rotation stop determination unit 52 determines that it is in a rotation stop state.

[0155] Next, referring to Figures 34 to 36, we will explain how to set the current command value when no phase adjustment processing is performed. As shown in Figure 34, the current command value is defined by the current amplitude and current phase in the dq axis coordinate system. The current amplitude Ia is expressed by equation (1). The current phase is defined by the angle in a counterclockwise direction with respect to the d axis. In the vector diagram, the meaning of the angle is emphasized and it is expressed as "phase angle φ", but "phase angle" has the same meaning as "phase". The d-axis current Id and the q-axis current Iq are expressed using the phase angle φ as "Id = Ia × cosφ, Iq = Ia × sinφ".

[0156]

number

[0157] The torque τ of the motor 60 is calculated by Equation (2.1) based on the d-axis current Id and the q-axis current Iq. In the equation, the constant p is the number of pole pairs, Ke is the magnetic flux of the magnet, Ld is the d-axis inductance, and Lq is the q-axis inductance. When Equation (2.1) is transformed to express the q-axis current Iq as a function of the d-axis current Id, Equation (2.2) of the equal torque curve is obtained.

[0158]

Number

[0159] The operating point with the minimum current amplitude on the equal torque curve is defined as the maximum efficiency operating point P. At the maximum efficiency operating point P, the maximum torque can be obtained with the smallest current. The phase angle φ of the maximum efficiency operating point P in this example is approximately 105°. Note that depending on the specifications, the phase angle φ of the maximum efficiency operating point P may be other values. Also, a circle with the amplitude of the maximum efficiency operating point P as the radius is represented as the equal amplitude circle. The current command calculation unit 50 calculates the dq-axis currents of the maximum efficiency operating point P as the current command values Id * so that the motor 60 outputs the torque corresponding to the torque command Trq. * 、Iq * 0]and Iq.

[0160] Fig. 35 shows the relationship between the motor position (electrical angle) when driving at the maximum efficiency operating point P and the three-phase currents Iu, Iv, and Iw. The three-phase currents Iu, Iv, and Iw are represented by Equation (3) according to the electrical angle θ and the phase angle φ. The units of the angles θ and φ are [°]. Note that the current values on the vertical axis are only shown for comparison with other figures and have no meaning in themselves.

[0161]

Number

[0162] Here, energizing the motor 60 while it is stopped is called "lock energizing." For example, when lock energizing is performed at an electrical angle of 30°, the current value becomes constant, as shown in Figure 36. Hereafter, in this specification, "maximum current" means the current with the largest absolute value. At an electrical angle of 30°, the maximum current flows in the V phase. Therefore, if lock energizing continues at an electrical angle of 30°, the current will concentrate in the V phase, which may cause uneven heat generation.

[0163] Therefore, the current command calculation unit 50 changes the phase of the current command value according to time so that the current is not supplied at the same current phase for longer than a predetermined time during lock energization. Next, the specific method of the phase adjustment process will be described for each embodiment.

[0164] (P1 embodiment) Referring to Figures 37 to 39, the phase adjustment process of the P1 embodiment will be explained. As shown in Figure 37, the current command calculation unit 50 changes the phase of the current command value on the equitorque curve with respect to the maximum efficiency operating point P. Figure 38 shows the change in the three-phase current when the phase adjustment process of the P1 embodiment is performed when the electrical angle is locked and energized at 30°. By changing the phase angle φ toward the advance angle from the maximum efficiency operating point P (φ = approximately 105°), the current of the phase through which the maximum current flows (in this case, the V phase) can be reduced. When the phase angle φ is 120°, the absolute values ​​of the V phase current Iv and the U phase current Iu match, as indicated by the circles, and when the phase angle φ exceeds 120°, the absolute value of the U phase current Iu becomes the maximum.

[0165] Figure 39 shows the time evolution of the three-phase current when the phase angle φ is oscillated between 105° and 125°. Compared to Figure 6, where no phase adjustment processing is performed, the phase currents Iu, Iv, and Iw repeatedly increase and decrease. In this case, the phase with the maximum current can be distributed between the V phase and the U phase, thus suppressing heat generation in a specific phase. The method of changing the phase angle φ is not limited to the method of oscillating the phase range at a constant speed as shown in Figure 9, but the phase angle φ may also be changed in steps at predetermined time intervals. Furthermore, a difference in the holding time for each phase angle φ may be provided.

[0166] In the P1 embodiment, by changing the phase of the current command value according to time, it is possible to prevent current from concentrating in a specific phase and uneven heat generation. Furthermore, by changing the potential-passing phase within a range based on the maximum efficiency operating point P, torque can be output to the motor 60 efficiently on average. However, in the phase adjustment process on the equitorque curve, the current amplitude Ia increases as it moves away from the maximum efficiency operating point P. Therefore, adjustment may be necessary in consideration of the current increase in phases other than the maximum current phase.

[0167] (P2 embodiment) Referring to Figures 40 to 42, the phase adjustment process of the P2 embodiment will be described. As shown in Figure 40, the current command calculation unit 50 changes the phase of the current command value on an equiamplitude circle with respect to the maximum efficiency operating point P. Figure 41 shows the change in the three-phase current when the phase adjustment process of the P2 embodiment is performed when the electrical angle is locked and energized at 30°. By changing the phase angle φ toward the advance angle side from the maximum efficiency operating point P (φ = approximately 105°), the current of the phase through which the maximum current flows (in this case, the V phase) can be reduced.

[0168] In the P2 embodiment, as in the P1 embodiment, it is possible to prevent current from concentrating in a specific phase and causing uneven heat generation. Furthermore, it is possible to output torque to the motor 60 efficiently on average. However, in the phase adjustment process on an equiamplitude circle, the current amplitude does not change, but the torque decreases as the phase angle φ moves away from the maximum efficiency operating point P. Figure 42 shows the change in torque ratio when the torque at the maximum efficiency operating point P is set to 1. In other embodiments, for example, an adjustment curve that is a compromise between an equitorque curve and an equiamplitude circle may be defined, and the current phase may be changed along that adjustment curve.

[0169] (P3 embodiment) Next, with reference to Figure 43, the phase adjustment process of the P3 embodiment will be described. In the P3 embodiment, the current command calculation unit 50 uses the hysteresis characteristics shown in Figure 4 in the phase adjustment process to change the phase of the current command value within the hysteresis region. When hysteresis characteristics are present, it is possible to maintain the pad load in the region between the original (i.e., high torque side) equitorque curve and the low torque side equitorque curve obtained by reducing the torque due to hysteresis. Furthermore, on the equiamplitude circle passing through the maximum efficiency operating point P on the original equitorque curve, the current phase can be changed without increasing the current amplitude.

[0170] Therefore, let QL be the intersection point on the retarded side of the constant torque curve on the low torque side and the constant amplitude circle, and QH be the intersection point on the advanced side, and let φL and φH be the phase angles corresponding to each intersection point QL and QH. The current command calculation unit 50 may, for example, store the region between the constant torque curve on the low torque side and the constant amplitude circle in a map and select any operating point within this region. The current command calculation unit 50 may also change the phase angle φ in the range of phase angles φL to φH on the constant torque curve on the low torque side. Similarly in the P3 embodiment, it is possible to prevent current from concentrating in a specific phase and uneven heat generation. In addition, torque can be output to the motor 60 efficiently on average.

[0171] (exempted from application) In each of the embodiments described above, the current command calculation unit 50 does not always perform phase adjustment processing, and does not need to perform phase adjustment processing in situations where heat generation in a particular phase is not a problem even when the motor is locked and energized. Therefore, if the motor 60 satisfies predetermined exemption requirements, the current command calculation unit 50 does not perform phase adjustment processing and continues to output the calculated current command value. The flowchart for determining whether the exemption requirements in the phase adjustment processing are met is based on Figure 31 of the stop position adjustment processing.

[0172] Thus, if lock current is not applied in the first place, or if heat generation in a specific phase does not become a problem even when lock current is applied, the current command calculation unit 50 does not perform phase adjustment processing. This avoids the current amplitude increasing in the P1 embodiment and the torque decreasing in the P2 embodiment at operating points far from the maximum efficiency operating point P, and allows the motor 60 to always operate at maximum efficiency.

[0173] (Other embodiments) (a) The vehicle on which the vehicle braking device of the present invention is installed is not limited to a four-wheeled vehicle having two rows of left and right pairs of wheels in the longitudinal direction of the vehicle, but may also be a six-wheeled or more vehicle having three or more rows of wheels in the longitudinal direction of the vehicle.

[0174] (b) In the above embodiment, it is assumed that the angle sensor 72 of the motor 60 is mainly used as the position sensor, but the stroke sensor 73 of the linear motion mechanism 85 may be used as the position sensor. In that case, the position controller 46 will adjust the position deviation ΔX to be as close to zero as possible, that is, the actual position X to the position command value X * The torque command value is calculated to approximate this value. The position adjustment range for the stop position adjustment process is set in the same way as in the above embodiment, based on the rotation angle converted from the stroke.

[0175] The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit.

[0176] The braking force control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the braking force control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the braking force control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. [Explanation of Symbols]

[0177] 30. Vehicle braking systems, 400 (400A, 400B, 400L, 400P) ... Braking force control unit, 40 (401H, 403H, 401L, 402L) ... Torque command calculation unit, 50...Current command calculation section, 60... Motor, three-phase motor 71. Load sensor, 72...Angle sensor (position sensor), 73...Stroke sensor (position sensor), 81-84...Electric brakes, 85...Linear drive mechanism, 900...vehicles, 91-94...wheels.

Claims

1. A vehicle braking system mounted on a vehicle (900) in which a multiphase motor (60) outputs torque, which is converted into linear power by a linear motion mechanism (85), and a plurality of electric brakes (81-84) are provided on each wheel to press against the corresponding wheels (91-94) and generate braking force, The system includes a torque command calculation unit (40) that calculates a torque command value for the motor based on a requested braking force commanded from an external source, and a current command calculation unit (50) that calculates a current command value for energizing the motor based on the torque command value, and a braking force control unit (400) that controls the braking force generated by each of the electric brakes. The electric brake is equipped with position sensors (72, 73) that detect the actual rotation angle of the motor or the actual position (θ, X) which is the actual stroke of the linear motion mechanism, or it is equipped with a load sensor (71) in addition to the position sensors that detects the actual load (F) which is the braking load actually pressed on the wheel. The relationship between the torque of the motor and the braking force generated in the electric brake has a hysteresis characteristic in which, as the torque increases, the braking force increases along the positive efficiency curve; as the torque decreases from the turning point where it changes from increasing to decreasing to the holding critical value, the braking force is maintained at a constant level; and as the torque decreases from the holding critical value, the braking force decreases along the negative efficiency curve. The torque command calculation unit calculates the actual position detected by the position sensor and assigns a position command value (θ ＊ , X ＊ Either perform position control that calculates the torque command value to approach the actual load detected by the load sensor, or calculate the load command value (F) based on the required braking force. ＊ The system switches between load control, which calculates the torque command value to approach the specified value, and position control, The process of reducing the motor's drive current and torque from the positive efficiency line to the negative efficiency line based on the hysteresis characteristics while maintaining braking force through the position control or load control is defined as a hysteresis-utilizing current reduction process. In lock current supply, where the motor is energized while its rotation is stopped to maintain braking force, if we define the process of adjusting the rotation stop position by position control so as to decrease or increase the absolute value of the current of any phase of interest as the stop position adjustment process, The aforementioned hysteresis-based current reduction process is, An overdrive operation is performed in which the torque of the motor is increased along the positive efficiency curve until the actual braking force, which is the braking force actually output by the electric brake, exceeds the required braking force by a predetermined amount. The process includes: reducing the motor drive current while maintaining the braking force at the end of the excess operation, and then reducing the motor torque along the reverse efficiency line until the actual braking force reaches the required braking force; The braking force control unit, when maintaining braking force, performs the excess operation of the hysteresis-utilizing current reduction process, and then, while also performing the return operation of the hysteresis-utilizing current reduction process, performs the stop position adjustment process to adjust the rotation stop position of the motor in the direction of decreasing braking force.

2. The current command calculation unit calculates a current command value defined by the current amplitude and current phase in the dq axis coordinates based on the torque command value. In the aforementioned lock energization, if we define the process of changing the phase of the current command value according to time so as not to continue energizing with the same current phase for more than a predetermined time as the phase adjustment process, then, The aforementioned braking force control unit, The vehicle braking device according to claim 1, wherein after performing the hysteresis-utilizing current reduction process and the stop position adjustment process, the phase adjustment process is further performed.

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