阅读说明：本技术 电机控制装置 (Motor control device ) 是由 中岛信赖 远藤豪 中村功一 于 2020-08-21 设计创作，主要内容包括：一种电机控制装置,包括至少一个电力转换器(60、601、602)、命令计算单元(401)、故障确定单元(55)和电力供应电流估计单元(51)。至少一个电力转换器连接在DC电源(11)和电机(80)之间。至少一个电力转换器被配置成通过操作多个开关元件(61-66)将DC电力转换成多相AC电力并将多相AC电力供应至电机。命令计算单元被配置成计算用于操作至少一个电力转换器以控制对电机的电传导的命令值。故障确定单元被配置成当流过至少一个电力转换器或电机的电机绕组的电流值超过过电流阈值时确定过电流故障。电力供应电流估计单元被配置成估计或检测电力供应电流(Ib),电力供应电流(Ib)是在DC电源与至少一个电力转换器之间流动的直流电流。(A motor control apparatus includes at least one power converter (60, 601, 602), a command calculation unit (401), a fault determination unit (55), and a power supply current estimation unit (51). At least one power converter is connected between the DC power source (11) and the motor (80). The at least one power converter is configured to convert the DC power into multi-phase AC power and supply the multi-phase AC power to the motor by operating a plurality of switching elements (61-66). The command calculation unit is configured to calculate a command value for operating the at least one power converter to control electrical conduction to the electric machine. The fault determination unit is configured to determine an overcurrent fault when a value of a current flowing through at least one power converter or a motor winding of the motor exceeds an overcurrent threshold. The power supply current estimation unit is configured to estimate or detect a power supply current (Ib) that is a direct current flowing between the DC power source and the at least one power converter.)

1. A motor control device comprising:

at least one power converter (60, 601, 602) connected between a DC power source (11) and an electric motor (80) and configured to convert DC power into multi-phase AC power by operating a plurality of switching elements (61-66) and supply the multi-phase AC power to the electric motor;

a command calculation unit (401) configured to calculate a command value for operating the at least one power converter to control electrical conduction to the electrical machine;

a fault determination unit (55) configured to determine an overcurrent fault when a value of a current flowing through the at least one power converter or a motor winding of the electric motor exceeds an overcurrent threshold; and

a power supply current estimation unit (51) configured to estimate or detect a power supply current (Ib) that is a direct current flowing between the DC power source and the at least one power converter, wherein a value of the power supply current supplied from the DC power source to the at least one power converter is defined by a positive value, and a value of the power supply current regenerated from the at least one power converter to the DC power source is defined by a negative value, wherein,

the fault determination unit stops the determination of the overcurrent fault when a negative value of the power supply current is smaller than a power supply current threshold that is a negative value.

2. A motor control device comprising:

at least one power converter (60, 601, 602) connected between a DC power source (11) and a motor (80) and configured to convert DC power into multi-phase AC power by operating a plurality of switching elements (61 to 66) and supply the multi-phase AC power to the motor;

a command calculation unit (402) configured to calculate a command value for operating the at least one power converter to control electrical conduction to the electrical machine;

a fault determination unit (55) configured to determine an overcurrent fault when a value of a current flowing through the at least one power converter or a motor winding of the electric motor exceeds an overcurrent threshold; and

a power supply current estimation unit (51) configured to estimate or detect a power supply current (Ib) that is a direct current flowing between the DC power source and the at least one power converter, wherein a value of the power supply current supplied from the DC power source to the at least one power converter is defined by a positive value, and a value of the power supply current regenerated from the at least one power converter to the DC power source is defined by a negative value, wherein,

the command calculation unit executes a command value reduction process of reducing an absolute value of the command value when the value of the power supply current is smaller than a power supply current threshold value that is a negative value, and

the fault determination unit stops the determination of the overcurrent fault when the command value lowering process is executed.

3. The motor control apparatus according to claim 1,

the motor comprises a plurality of motor winding units (841, 842),

the plurality of cells respectively correspond to a plurality of systems, each of the plurality of systems including components related to electrical conduction of the cells through the at least one power converter,

the plurality of systems are configured to communicate with each other and

when one of the plurality of systems determines that the value of the power supply current of the one of the plurality of systems is less than the power supply current threshold that is negative, the one of the plurality of systems sends information to the remaining ones of the plurality of systems that the value of the power supply current of the one of the plurality of systems is less than the power supply current threshold that is negative via a flag.

4. The motor control apparatus according to claim 2,

the motor comprises a plurality of motor winding units (841, 842),

the plurality of cells respectively correspond to a plurality of systems, each of the plurality of systems including components related to electrical conduction of the cells through the at least one power converter,

the plurality of systems are configured to communicate with each other and

when one of the plurality of systems determines that the command value reduction processing in the one of the plurality of systems is performed, the one of the plurality of systems transmits information about that the one of the plurality of systems determines that the command value reduction processing in the one of the plurality of systems is performed to the remaining systems of the plurality of systems by a flag.

5. The motor control apparatus according to claim 3,

the components include the motor control device and the DC power supply.

6. The motor control apparatus according to claim 4,

the components include the motor control device and the DC power supply.

Technical Field

The present disclosure relates to a motor control device.

Background

In general, in a motor control apparatus that determines an overcurrent fault of a power converter or a motor winding, a technique is proposed to avoid erroneous determination of the overcurrent fault due to a current caused by regenerative energy in a normal state.

For example, the motor control device disclosed in patent document 1 stops overcurrent fault determination when it is determined during normal operation that the input voltage of the power converter is outside the operating range.

Documents of the prior art

Patent document

Patent document 1: JP 2018-182780A

Disclosure of Invention

However, for example, when the power supply voltage is low, the increase in the input voltage when regenerative energy is generated is small. Therefore, it may be difficult to perform erroneous determination of the overcurrent fault only by the input voltage. In the case of application to a motor control device of a vehicle, an operation in a low voltage state is required to cope with autonomous driving. Therefore, this concern will be amplified.

An object of the present disclosure is to provide a motor control device that avoids erroneous determination of an overcurrent fault due to regenerative current.

Another exemplary embodiment of the present disclosure provides a motor control apparatus including at least one power converter, a command calculation unit, a fault determination unit, and a power supply current estimation unit. At least one power converter is connected between a DC (direct current) power source and the motor. The at least one power converter is configured to convert DC power into multi-phase AC (alternating current) power by operating the plurality of switching elements, and supply the multi-phase AC power to the motor. The command calculation unit is configured to calculate a command value for operating the at least one power converter to control electrical conduction to the electric machine. The fault determination unit is configured to determine an overcurrent fault when a value of a current flowing through at least one power converter or a motor winding of the motor exceeds an overcurrent threshold. The power supply current estimation unit is configured to estimate or detect a power supply current, which is a direct current flowing between the DC power source and the at least one power converter. The value of the power supply current supplied from the DC power source to the at least one power converter is defined by a positive value, and the value of the power supply current regenerated from the at least one power converter to the DC power source is defined by a negative value. When the value of the power supply current is smaller than the power supply current threshold value that is a negative value, the command calculation unit executes command value lowering processing that lowers the absolute value of the command value. The fault determination unit stops determination of the overcurrent fault when the command value lowering process is executed.

Here, "the value of the power supply current is smaller than the negative power supply current threshold" means "the negative value of the power supply current is larger than the negative power supply current threshold on the negative side", that is, "the absolute value of the negative power supply current is larger than the absolute value of the negative power supply current threshold".

When the power supply voltage is low and the increase of the input voltage when regenerative energy is generated is small, erroneous determination of an overcurrent fault can be avoided.

Another exemplary embodiment of the present disclosure provides a motor control apparatus including at least one power converter, a command calculation unit, a fault determination unit, and a power supply current estimation unit. At least one power converter is connected between the DC power source and the electric machine. The at least one power converter is configured to convert DC power into multi-phase AC power by operation of the plurality of switching elements and supply the multi-phase AC power to the motor. The command calculation unit is configured to calculate a command value for operating the at least one power converter to control electrical conduction to the electric machine. The fault determination unit is configured to determine an overcurrent fault when a current flowing through the at least one power converter or a motor winding of the motor exceeds an overcurrent threshold. The power supply current estimation unit is configured to estimate or detect a power supply current, which is a direct current flowing between the DC power source and the at least one power converter. The value of the power supply current supplied from the DC power supply to the at least one power converter is defined as positive. The value of the power supply current regenerated from the at least one power converter to the DC power source is defined as negative. When the value of the power supply current is smaller than the power supply current threshold value that is negative, the command calculation unit executes command value lowering processing that lowers the absolute value of the command value. The fault determination unit stops determination of the overcurrent fault when the command value lowering process is executed.

When the power supply current is less than the negative power supply current threshold value, the motor control device decreases the absolute value of the command value to suppress the overvoltage and stops the determination of the overcurrent fault. Therefore, it is possible to more reliably avoid erroneous determination of the overcurrent fault under the condition that the overcurrent fault is unlikely to occur.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

fig. 1 is an overall configuration diagram showing an electric power steering apparatus to which a motor control apparatus of each embodiment is applied;

fig. 2 is an overall configuration diagram showing a single-system motor control device according to a first embodiment and a second embodiment;

fig. 3 is a block diagram of a control according to the first embodiment;

fig. 4 is a flowchart showing an overcurrent fault determination shielding process according to the first embodiment;

fig. 5 is a time chart showing the overcurrent fault determination shielding process according to the first embodiment;

fig. 6 is a block diagram of a control according to a second embodiment;

fig. 7 is a flowchart showing an overcurrent fault determination shielding process according to the second embodiment;

fig. 8 is a time chart showing an overcurrent fault determination shielding process according to the second embodiment;

fig. 9 is an overall configuration diagram showing a two-system motor control device according to a third embodiment; and

fig. 10 is a schematic diagram showing the configuration of a double-winding motor.

Detailed Description

"embodiments" means embodiments of the present application. The motor control device will be described with reference to a number of embodiments shown in the drawings. This motor control device is used as a control device for driving a steering assist motor in an electric power steering device for a vehicle. In the following embodiments, substantially the same structural components are denoted by the same reference numerals, thereby simplifying the description. Hereinafter, the first to third embodiments are collectively referred to as "the present embodiment".

[ electric Power steering apparatus ]

Fig. 1 shows the overall configuration of a steering system 99 including an electric power steering apparatus 90. Although the electric power steering apparatus 90 shown in fig. 1 is of a column assist type, the motor control apparatus 10 may be applied to a rack assist type electric power steering apparatus. The steering system 99 includes: a steering wheel 91, a steering shaft 92, a pinion 96, a rack shaft 97, wheels 98, an electric power steering apparatus 90, and the like. The steering shaft 92 is connected to the steering wheel 91.

A pinion 96 provided at an end of the steering shaft 92 meshes with a rack shaft 97. A pair of wheels 98 are provided at both ends of the rack shaft 97 via tie rods, for example. When the driver rotates the steering wheel 91, the steering shaft 92 connected to the steering wheel 91 is also rotated. The rotational motion of the steering shaft 92 is converted into linear motion of the rack shaft 97 by the pinion 96, and the pair of wheels 98 are steered by an angle corresponding to the displacement amount of the rack shaft 97.

The electric power steering apparatus 90 includes a steering torque sensor 94, the motor control apparatus 10, the motor 80, a reduction gear 89, and the like. A steering torque sensor 94 is provided at an intermediate portion of the steering shaft 92 to detect a steering torque trq applied by the driver. The motor control device 10 acquires information such as the steering torque trq, the steering speed, and the vehicle speed from the outside, and controls the driving of the motor 80 so that the motor 80 outputs the expected assist torque calculated from the information. The assist torque generated by the motor 80 is transmitted to the steering shaft 92 via the reduction gear 89.

The motor control device 10 includes an inverter 60 as a "power converter". The inverter 60 converts DC power from the battery 11 as a "DC power source" into multi-phase AC power and supplies the power to the motor 80. Hereinafter, the power supply voltage of the battery 11 will be referred to as Vb. Further, the direct current flowing between the battery 11 and the inverter 60 is referred to as "power supply current Ib". The value of the power supply current Ib is defined to be positive when the power supply current Ib is supplied from the battery 11 to the inverter 60, and negative when the power supply current Ib is regenerated from the inverter 60 to the battery 11.

For example, when the wheels travel on the curb while the vehicle is traveling, the wheels 98 are sharply steered, and external force is reversely input to the output shaft of the motor 80 via the rack shaft 97. At this time, regenerative current is generated in the motor 80 by the regenerative energy. In addition, when the steering wheel 91 is operated in an unloaded state in which the wheels 98 are lifted (jammed up), the motor 80 generates a counter electromotive force. Further, in a dual system motor having two sets of motor windings, when there is a difference in the outputs of the respective systems, one of the motor windings may perform a power supply operation (power operation), and the other may perform a regeneration operation.

In the present embodiment, the following points are focused: when such a regenerative current is generated, switching of the permission or cancellation of the overcurrent fault determination. Hereinafter, the configuration and operational effects of the motor control device of each embodiment will be described. Furthermore, a unit of a group of components related to the electrical conduction of the motor windings is defined as a "system". The first embodiment and the second embodiment will describe a single-system motor control device, and the third embodiment will describe a dual-system motor control device that is representative of a plurality of systems.

(first embodiment)

A motor control device 101 according to a first embodiment is described with reference to fig. 2 to 5. As shown in fig. 2, the motor 80 is a three-phase brushless motor having three-phase motor windings 84 including a U-phase winding 81, a V-phase winding 82, and a W-phase winding 83. The current sensor 75 detects phase currents Iu, Iv, Iw flowing through the inverter 60 or the motor winding 84. The rotation angle sensor 85 detects an electrical angle θ of the motor 80.

The motor control device 101 includes the inverter 60, the microcomputer 30, the current sensor 75, and the like. The inverter 60 converts the DC power of the battery 11 into three-phase AC power and excites the motor windings 84 by operation of the six bridged switching elements 61 to 66. The switching elements 61 to 66 may be provided by MOSFETs. The switching elements 61, 62, and 63 are upper arm switching elements of the U-phase, V-phase, and W-phase of the first inverter 60, respectively. The switching elements 64, 65, and 66 are lower arm switching elements of the U-phase, V-phase, and W-phase of the first inverter 60, respectively.

A power supply relay 12 is provided between the battery 11 and the inverter 60, and a smoothing capacitor 16 is provided at an input portion of the inverter 60. Further, as shown by the broken line, a power supply current sensor 15 that detects the power supply current Ib may be provided.

The microcomputer 30 includes a CPU, ROM, RAM, I/O (not shown), a bus for connecting these components, and the like. The motor control device 101 executes software processing by the CPU executing a program stored in advance, and executes control by hardware processing of a dedicated electronic circuit. The microcomputer 30 of the first embodiment includes a command calculation unit 40, a power supply current estimation unit 51, a fault determination unit 55, and the like.

The command calculation unit 40 operates the inverter 60 by the drive signal Dr to calculate a command value for controlling the electrical conduction to the motor 80. The fault determination unit 55 determines that it has an overcurrent fault when the phase currents Iu, Iv, Iw flowing through the inverter 60 or the motor winding 84 exceed an overcurrent threshold. The power supply current estimation unit 51 estimates or detects the power supply current Ib.

Next, a detailed control configuration of the motor control device 101 will be described with reference to fig. 3. In fig. 3, voltages Vu, Vv, Vw and currents Iu, Iv, Iw of the three phases are collectively represented as one line. As for the electrical angle θ used for the coordinate conversion calculation, a signal line from the rotation angle sensor 85 is omitted, and an input arrow is shown.

As a configuration of current feedback control by vector control, the command calculation unit 401 includes a current command value calculation unit 41, a three-phase/two-phase conversion unit 42, current deviation calculation units 431, 432, controllers 441, 442, and a two-phase/three-phase conversion unit 46. The current command value calculation unit 41 calculates a dq-axis current command value Id based on the steering torque trq and the like^*、Iq^*. The three-phase/two-phase converting unit 42 converts the phase currents Iu, Iv, Iw into two phases by using the electrical angle theta,and feeds back the actual currents Id, Iq on the dq axis.

The current deviation calculation unit 431 calculates the d-axis current command value Id^*The current deviation Δ Id from the d-axis current Id. The current deviation calculation unit 432 calculates the q-axis current command value Iq^*A current deviation Δ Iq from the q-axis current Iq. The d-axis current control unit 441 calculates a d-axis voltage command value Vd by PI control^*So that the current deviation Δ Id approaches 0. The q-axis current control unit 442 calculates a q-axis voltage command value Vq by PI control^*So that the current deviation Δ Iq approaches 0.

The two-phase/three-phase conversion unit 46 converts the dq-axis voltage command value Vd by using the electrical angle θ^*、Vq^*Converted into three-phase voltage command value Vu^*、Vv^*、Vw^*. Based on three-phase voltage command value Vu^*、Vv^*、Vw^*Is output to the inverter 60. By operating the plurality of switching elements 61 to 66 based on the drive signal Dr, the inverter 60 converts Direct Current (DC) power of the battery 11 into three-phase AC (alternating current) power, and supplies the three-phase AC power to the motor 80.

The fault determination unit 55 determines that an overcurrent fault exists when the phase currents Iu, Iv, Iw flowing through the motor windings 81, 82, 83 of the inverter 60 or the motor 80 exceed an overcurrent threshold. Specifically, the fault determining unit 55 determines that an overcurrent fault exists when the phase currents Iu, Iv, Iw that change positively and negatively in a sine wave exceed a positive current threshold or a negative current threshold, or the absolute values of the respective phase currents Iu, Iv, Iw exceed a current threshold.

During normal operation, when a short-circuit fault of the switching elements 61 to 66 of the inverter 60 occurs or a power fault or a ground fault of the motor windings 81, 82, 83 occurs, the fault determination unit 55 determines that an overcurrent fault exists. At this time, the driving of the inverter 60 is stopped or the power supply relay 12 is cut off to realize the fail-safe. For example, measures at the time of failure are taken to notify the vehicle ECU of failure information and give a warning to the driver, for example, via the in-vehicle LAN.

However, when the back electromotive force generated by the phase currents Iu, Iv, Iw due to the reverse input of the external force temporarily increases, the fault determination unit 55 may determine that an overcurrent fault exists although not a short-circuit fault of the element or the current path. As a result, inconvenience occurs, for example, the driving of the inverter 60 is stopped and the steering assist function is lost. In addition, the warning may cause excessive anxiety in the driver.

To solve this problem, in the related art of patent document 1(JP 2018-. For example, when the power supply voltage Vb is low and the increase of the input voltage when regenerative energy is generated is small, the related art in patent document 1 may erroneously determine that there is an overcurrent fault without stopping the overcurrent fault determination when a normal regenerative current occurs. It is necessary to operate in a low voltage state to cope with the automatic driving, and therefore such a fear will be amplified.

In the present embodiment, whether or not the normal regenerative current is generated is determined based on a parameter other than the input voltage. The present disclosure can appropriately avoid erroneous determination of an overcurrent fault even when the power supply voltage Vb is low and the increase of the input voltage when regenerative energy is generated is small. The motor control device 101 includes a power supply current estimation unit 51 that estimates or detects the power supply current Ib. In the present embodiment, the power supply current Ib of interest is a regenerative current flowing from the inverter 60 to the battery 11, that is, a negative power supply current Ib.

FIG. 3 is a diagram showing that the power supply current estimating unit 51 instructs the value Vq based on the dq-axis voltage^*、Vd^*A diagram of a configuration of estimating the power supply current Ib by the dq-axis currents Iq, Id and the reference voltage Vref. The estimated value Ib _ est of the electric power supply current is calculated by equation (1). The reference voltage Vref is a constant that is not dependent on the actual inverter input voltage, e.g. 12V]。

lb_est＝(Vd^＊×ld+Vq^＊×lq)/Vref (1)

Alternatively, the power supply current estimation unit 51 may also acquire the detection value Ib _ sns of the power supply current detected by the power supply current sensor 15 shown by a broken line in fig. 2. In the present specification, it is described that "the power supply current estimation unit 51 detects the power supply current Ib" includes that the power supply current estimation unit 51 acquires the power supply current Ib detected by the power supply current sensor 15.

The value of the power supply current Ib estimated or detected by the power supply current estimation unit 51 is compared with the negative power supply current threshold value (-X) shown in fig. 4 and 5. Here, the power supply current estimation unit 51 may notify the fault determination unit 55 of the power supply current Ib, and the fault determination unit 55 may compare the value of the power supply current Ib with the threshold value (-X). In this case, the fault determination unit 55 stops the overcurrent fault determination when "Ib < (-X)" is satisfied. Hereinafter, "stop overcurrent fault determination" may be restated as "shield overcurrent fault determination". Further, this process according to the present embodiment is referred to as an "overcurrent fault determination mask process".

Alternatively, the power supply current estimation unit 51 compares the value of the power supply current Ib with the threshold value (-X), and when "Ib < (-X)" is satisfied, the power supply current estimation unit 51 notifies the failure determination unit 55 of the regeneration current excess (excess) flag Flg 1. The fault determination unit 55 that receives the regeneration current excess flag Flg1 stops the overcurrent fault determination.

A specific example of the overcurrent fault determination shielding process according to the first embodiment is described with reference to the flowchart of fig. 4 and the timing chart of fig. 5. This process is repeatedly executed during the operation of the motor control apparatus 101. In fig. 5, the time difference due to the communication delay is ignored.

At S11, the power supply current estimation unit 51 estimates or detects the power supply current Ib. At S12, it is determined whether the value of the power supply current Ib is smaller than the negative power supply current threshold value (-X). In the case of yes at S12, the fault determination unit 55 stops overcurrent fault determination at S16. In the case of no at S12, the fault determination unit 55 permits overcurrent fault determination at S21.

In fig. 5, before time tx, the value of the power supply current Ib is equal to or larger than the threshold value (-X), and thus overcurrent fault determination is permitted. After time tx, the power supply current Ib is less than the threshold (-X), and thus the overcurrent fault determination is masked.

Here, the determination at S12 may also be made by the fault determination unit 55 or the power supply current estimation unit 51. When the failure determination unit 55 makes the determination at S12, in the case of yes at S12, it proceeds directly to S16. When the power supply current estimating unit 51 makes the determination at S12, in the case of yes at S12, the power supply current estimating unit 51 notifies the fault determining unit 55 of the regenerative current excess flag Flg 1. This process is indicated by the dashed line table as S13.

As shown in fig. 5, the regeneration current excess flag Flg1 is OFF (OFF) before time tx and ON (ON) after time tx. At time tx, the overcurrent fault determination transitions from the permit state to the stop state.

At S22, the fault determination unit 55 determines whether the absolute value | I # | of the phase current is greater than the current determination threshold Ith. The symbol "#" represents any one of "u, v, w". When the determination at S22 is yes, measures against the fault, such as a drive stop of the inverter 60 or an interruption of the power supply relay 12, are performed at S23. When the determination at S22 is no, the process terminates.

As described above, in the first embodiment, the overcurrent fault determination is stopped when the value of the power supply current Ib generated from regenerative energy is smaller than the negative power supply current threshold value (-X). When the power supply voltage Vb is low and the increase of the input voltage when regenerative energy is generated is small, erroneous determination of an overcurrent fault can be avoided.

(second embodiment)

A motor control device 102 according to a second embodiment will be described with reference to fig. 6 to 8. The overall configuration of the motor control device is the same as that of fig. 2 of the first embodiment, and reference numerals of "motor control device" and "command calculation unit" are replaced with "102" and "402", respectively. As shown in fig. 6, in the motor control device 102 of the second embodiment, the command calculation unit 402 includes a command value reduction unit 45 in addition to the configuration of the first embodiment.

When a predetermined condition is satisfied, command value reduction unit 45 executes making voltage command value Vd^*、Vq^*And the processed voltage command value Vd is reduced^**、Vq^**Output to the two-phase/three-phase conversion unit 46. For example, the command value reduction unit 45 reduces the voltage command value Vd by adding the voltage command value Vd to the voltage^*、Vq^*The command value reduction process is executed by multiplying a suppression gain calculated from the ratio of the absolute value | Ib | of the power supply current to the target value. This calculation method is disclosed in CN 105720882B (corresponding to US 9548688B 2 and JP 6428248B 2).

In the second embodiment, "the value of the negative power supply current Ib estimated or detected by the power supply current estimation unit 51 is smaller than the negative power supply current threshold value (-X)" is a condition for executing the command value lowering process. When the command value lowering process is executed, the fault determination unit 55 stops the overcurrent fault determination.

That is, in the first embodiment, the overcurrent fault determination is directly stopped when "Ib < -X" is satisfied, whereas in the second embodiment, the overcurrent fault determination is indirectly stopped by executing the command value reduction process when "Ib < -X" is satisfied. In one exemplary configuration for achieving this operation, the power supply current estimation unit 51 notifies the command value reduction unit 45 of the power supply current Ib, and the command value reduction unit 45 compares the value of the power supply current Ib with the power supply current threshold value (-X). When "Ib < -X" is satisfied, the command value reduction unit 45 performs the command value reduction process and outputs a command value reduction flag Flg2 to the failure determination unit 55.

In another exemplary configuration, as shown in parentheses and broken lines of fig. 6, when the power supply current estimation unit 51 determines that "Ib < -X" is satisfied, the power supply current estimation unit 51 outputs an execution command of the command value reduction process to the command value reduction unit 45 and outputs a command value reduction flag Flg2 to the failure determination unit 55.

The process according to the second embodiment will be described with reference to the flowchart of fig. 7 and the timing chart of fig. 8The current fault determines a specific example of the shielding process. Since the processes of S11, S12, S16, and S21 to S23 of fig. 7 are substantially the same as those of fig. 4 of the first embodiment, a repetitive description will be omitted. In the second embodiment, in the case of yes at S12, command value lowering unit 45 lowers voltage command value Vd at S14^*、Vq^*Absolute value of (a). In the case of no at S12, S14 is skipped.

At S15, it is determined whether or not the command value lowering process is performed, and the failure determination unit 55 is notified of, for example, the command value lowering flag Flg 2. In this case, it may be determined that the fault determination unit 55 receives the command-value-lowering flag Flg2, or that the power-supply-current estimation unit 51 or the command-value lowering unit 45 transmits the command-value-lowering flag Flg 2. Alternatively, the monitor voltage command value Vd is determined without using the flag^*、Vq^*To perform command value reduction processing. In the case of yes at S15, the fault determination unit 55 stops overcurrent fault determination at S16. In the case of no at S15, the fault determination unit 55 permits overcurrent fault determination at S21.

In fig. 8, since the value of the power supply current Ib before time tx is equal to or larger than the threshold value (-X), the command value lowering flag Flg2 is off. Since the value of the power supply current Ib is smaller than the threshold value (-X) after the time tx, the command value lowering flag Flg2 is on. At time tx, the overcurrent fault determination transitions from the permit state to the stop state.

As described above, in the second embodiment, when the value of the power supply current Ib is smaller than the negative power supply current threshold value (-X), it is determined that the regenerative current is excessive. In this case, the voltage command value Vd is lowered to avoid an overvoltage^*And the absolute value of Vq and stops overcurrent fault determination. Therefore, under the condition that the overcurrent fault is unlikely to occur, erroneous determination of the overcurrent fault can be avoided more reliably.

(third embodiment)

A motor control device 103 according to a third embodiment will be described below with reference to fig. 9 and 10. When multiple systems are applied to a motor having multiple sets of motor windings, the unit of the element group associated with the electrical conduction of each motor winding is defined as a "system". The motor control arrangement 103 comprises two inverters 601, 602, and the two inverters 601, 602 excite the respective two sets of motor windings 841, 842. In fig. 9, reference numerals of switching elements in the inverter 601 and the inverter 602 are omitted.

The first inverter 601 of the first system is supplied with DC power from the battery 111 of the power supply voltage Vb1, and the second inverter 602 of the second system is supplied with DC power from the battery 112 of the power supply voltage Vb 2. Power relays 121 and 122 are provided between the battery 111 and the inverter 601 and between the battery 112 and the inverter 602, respectively. Smoothing capacitors 161, 162 are provided at input portions of the inverter 601 and the inverter 602, respectively. The power supply current of the first system is referred to as Ib1, and the power supply current of the second system is referred to as Ib 2. Similarly as in fig. 2, as indicated by broken lines, power supply current sensors 151, 152 that detect the power supply current Ib1 and the power supply current Ib2, respectively, may be provided.

Each of the first microcomputer 301 and the second microcomputer 302 has a configuration similar to that of the microcomputer 30 of fig. 2. The first microcomputer 301 acquires the phase currents Iu1, Iv1, Iw1 of the first system from the current sensor 751, and acquires the electrical angle θ 1 from the rotation angle sensor 851. The first microcomputer 301 calculates the drive signal Dr1 from the steering torque trq based on the feedback information. The first inverter 601 excites the U1, V1 and W1 phases of the motor winding 841 in accordance with the drive signal Dr 1.

The second microcomputer 302 acquires the phase currents Iu2, Iv2, Iw2 of the second system from the current sensor 752 and acquires the electrical angle θ 2 from the rotation angle sensor 852. The second microcomputer 302 calculates the drive signal Dr2 from the steering torque trq based on the feedback information. The second inverter 602 energizes the U2, V2, and W2 phases of the motor winding 842 in accordance with the drive signal Dr 2.

In the configuration in which the steering torque sensor is redundantly provided, the steering torques trq1 and trq2 may be input for each system. The microcomputers 301, 302 of the respective systems are capable of transmitting and receiving information to and from each other by inter-computer communication between the microcomputers.

As shown in fig. 10, the motor 80 is configured as a double winding motor in which two sets of motor windings 841, 842 are coaxially disposed. The two sets of motor windings 841, 842 have similar electrical characteristics and are located on a common stator while being offset from each other by an electrical angle of 30 degrees. For this reason, the phase currents supplied to the windings 841, 842 are controlled to have the same magnitude and a phase difference of 30 degrees.

In such a dual system configuration, an external force may be reversely input to the output shaft of the motor 80, the steering wheel 91 may be operated in a no-load state in which the wheels 98 are jacked up, and a difference in output of each system may cause one to perform a power supplying operation and the other to perform a regenerating operation. That is, energy is transmitted from the inverter having a large output to the inverter having a small output via the motor output shaft. For example, it is assumed that when the second system performs the power supply operation and the first system performs the regeneration operation, the power supply voltage Vb1 of the first system is low and the negative value of the power supply current Ib1 is smaller than the power supply current threshold (-X).

At this time, the first microcomputer 301 stops the overcurrent fault determination. On the other hand, the second microcomputer 302 does not need to stop the overcurrent fault determination. However, in order to coordinate the control in the two systems, it is preferable that the second microcomputer 302 also stops the overcurrent fault determination according to the first microcomputer 301. In the third embodiment, information as a condition for stopping the overcurrent fault determination of any system in the system is transmitted to other systems through the flag.

Specifically, "information to determine that the value of the power supply current Ib is smaller than the negative power supply current threshold value (-X)" according to the first embodiment is transmitted by the regenerative current excess flag Flg 1. The "information to execute the command-value reduction processing" according to the second embodiment is transmitted by the command-value reduction flag Flg 2. As a result, the amount of communication information can be minimized and the communication load can be suppressed.

Note that although the case where one system performs the power supply operation and the other system performs the regeneration operation due to the difference in the outputs of the two systems has been described, the same operational effect can be obtained even when regenerated energy is generated in both systems by the reverse input of the external force. Further, the technique of the third embodiment is not limited to two systems, but may be similarly extended to a plurality of systems of motor control devices of three or more systems.

(other embodiments)

(a) In the above-described embodiment, when the power supply current Ib falls below the negative power supply current threshold value (-X), the overcurrent fault determination is immediately stopped or the command value reduction process is executed. However, in order to avoid erroneous determination due to noise or the like, when the same state continues for a predetermined time, the process may proceed to the next process.

(b) In the third embodiment, information as a condition for stopping the overcurrent fault determination in any system is transmitted to other systems by a signal other than the flag. For example, the value or the converted value of the power supply current Ib may be transmitted to another system.

(c) In the above embodiment, the sign of the electric power supply current Ib is defined as "the direction of supply from the battery 11 to the inverter 60 is positive, and the direction of regeneration from the inverter 60 to the battery 11 is negative". Since this is only a matter of limitation, there is no essential difference even if it is defined that "the direction from the battery 11 to the inverter 60 is negative, and the direction from the inverter 60 to the battery 11 is positive". In other words, it indicates that "the current (-Ib) in the opposite direction to the power supply current defined in the above-described embodiment" is defined as "the power supply current (-Ib)". Therefore, a technique in which the definition of symbols is simply replaced with respect to the above-described embodiment is naturally included in the technical scope of the present disclosure.

(d) The motor control device of the present disclosure is not limited to a three-phase motor, and may be similarly applied to a multi-phase motor having four or more phases. Further, the present disclosure is not limited to the steering assist motor of the electric power steering apparatus, but may be applied to any motor in which a negative power supply current may flow.

The present disclosure should not be limited to the above-described embodiments, and various other embodiments may be implemented without departing from the scope of the present invention.

The control units and techniques according to this disclosure may be implemented by a special purpose computer provided by constituting a processor and a memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control circuits and methods described in this disclosure may be implemented by a special purpose computer configured as a processor with one or more special purpose hardware logic circuits. Alternatively, the control circuits and methods described in this disclosure may be implemented by one or more special purpose computers configured as a combination of a processor and memory programmed to perform one or more functions and a processor configured with one or more hardware logic circuits. Further, the computer program may store instructions to be executed by a computer as a computer-readable non-transitory tangible recording medium.