JP2007330099A - Electric power-steering controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concrete implementation means that simply executes failure determination of a control system in an electric power-steering controller. <P>SOLUTION: The electric power-steering controller is provided with a voltage control means which controls a voltage applied to a motor on the basis of a d-axis current command value and q-axis current command value that are set by a d-q command value setting means, and a d-axis current detection value and q-axis current detection value that are obtained by subjecting a three-phase AC current, actually flowing in the motor and detected by a current detection part, to d-q coordinate-system conversion; and a failure determination means for determining a failure when a phase current detection value is out of a first prescribed allowable range, continues for over a first prescribed period of time. The failure determination means executes the failure determination in a cycle of less than 1/2 f when a sine-wave frequency of a three-phase current is set as f. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric power steering control device for assisting steering by applying torque generated by a motor to a steering mechanism.

  2. Description of the Related Art Conventionally, there is known an electric power steering control device that transmits torque generated by a motor such as a three-phase brushless motor to a steering mechanism, thereby assisting steering. (For example, refer to Patent Document 1).

JP 2001-187578 A

  FIG. 14 shows the relationship between the motor M that assists the electric power steering control device and the controller C that controls the motor M, and FIG. 15 shows a block diagram showing the functional configuration of the conventional electric power steering control device.

FIG. 14 shows the relationship between the controller C that controls the electric power steering control device, the value that is input to the controller C, and the motor M that is controlled by the controller C. Although not shown in the specification, the motor M supplementarily supplies torque to the electric power steering control device, and the motor M is driven by a motor driver 52 controlled by the controller C. The controller C includes a vehicle speed V acquired by the vehicle speed sensor 42, a steering torque T detected by the torque sensor 43 and phase-compensated via the phase compensation circuit 44, and a resolver R connected to the motor M. The rotor angle θ _re of the motor M detected by the rotor angle detection circuit 45 is input, and further, the motor M is subjected to current feedback control by the controller C. Therefore, the controller C receives the three detected by the motor current detection unit 41. The phase current detection value is input.

Next, FIG. 15 will be described. In this motor control device, the vehicle speed V detected by the vehicle speed sensor 42 and the steering torque T detected by the torque sensor 43 and phase-compensated via the phase compensation circuit 44 are input to the controller C. Further, the motor control device determines a target current command value I ′ _a ^* (effective value of the three-phase current flowing in the U phase, the V phase, and the W phase) that is a command value of the three-phase current that is supplied to the motor M. A target current calculation unit 61 is provided, and the rotor angle θ _re of the motor M detected by the resolver R and the rotor angle detection circuit 45 is output via the rotor angular velocity calculation unit 65 in order to improve the steering feeling. The convergence correction value I _CO ^* determined from the rotor angular velocity _ωre and the vehicle speed V is calculated, and the convergence correction value is given to the adder 62. In the addition unit 62, the target current command value I ′ _a ^* input from the target current calculation unit 61 and the convergence correction value I _CO ^* input from the convergence correction unit 64 are added, and the U phase, V, A target current command value I _a ^* after convergence is set that indicates the amplitude of the three-phase current to be applied to the phase and the W phase. Further, in order to make it possible to handle the current value as a direct current amount unrelated to the rotor angle θ _re of the motor M, the q-axis current command value calculation unit 66 performs the above-described convergence corrected target current command value I _a ^*. _Is subjected to dq coordinate transformation to set a q-axis current command value i _qa ^* . On the other hand, the d-axis current command value i _da ^* is set to zero.

The d-axis current command value I _da ^* and the q-axis current command value I _qa ^* are input to the subtraction units 67d and 67q, respectively. These subtractors 67d and 67q include a U-phase current detector 41u for detecting a U-phase current i _ua that is actually energized in the U-phase of the motor M, and a V-phase current that actually flows in the V-phase. V-phase current detection unit 41v outputs three-phase AC / d-q d-axis current detection value obtained through the coordinate transformation unit 68 I _da and the q-axis current detection value I _qa is provided for detecting the i _va It is like that. Accordingly, the subtraction units 67d and 67q output the deviation between the d-axis current command value I _da ^* and the d-axis current detection value I _{da and} the deviation between the q-axis current command value I _qa ^* and the q-axis current detection value I _qa , respectively. Will be.

Deviations output from the subtracting units 67d and 67q are respectively supplied to a d-axis current PI (proportional integral) control unit 69d and a q-axis current PI control unit 69q, and d-axis voltage command value V _da ^* and q-axis voltage, respectively. The command value V _qa ^* is obtained.

The d-axis voltage command value V _da ^* and the q-axis voltage command value V _qa ^* are input to the dq / three-phase AC coordinate conversion unit 72. Also in this d-q / three-phase AC coordinate conversion section 72, the rotor angle rotor angle theta _re detected by the detection circuit 45 is input, d-q / three-phase AC coordinate conversion section 72, the following According to the equation (1), the d-axis voltage command value V _da ^* and the q-axis voltage command value V _qa ^* are converted into the command values V _ua ^* and V _va ^* of the three-phase AC coordinate system. Then, the obtained U-phase voltage command value V _ua ^* and V-phase voltage command value V _va ^* are input to the three-phase PWM modulation unit 51.

However, the W-phase voltage command value _Vwa ^* is not calculated by the dq / three-phase AC coordinate conversion unit 72, but the U-phase voltage command value _Vua ^* calculated by the dq / three-phase AC coordinate conversion unit 72 ^. Based on the V-phase voltage command value V _va ^* , the W-phase voltage command value calculation unit 73 calculates the value. That is, the W-phase voltage command value calculation unit 73 receives the U-phase voltage command value V _ua ^* and the V-phase voltage command value V _va ^* from the dq / three-phase AC coordinate conversion unit 72, and the W-phase voltage command value calculation unit 73 voltage command value computing unit 73 obtains a W-phase voltage command value _{V wa} ^* by subtracting the U-phase voltage command value _{V ua} ^* and V-phase voltage command value _{V va} ^* from zero.

The W-phase voltage command value V _wa ^* calculated by the W-phase voltage command value calculation unit 73 is given to the three-phase PWM modulation unit 51 in the same manner as the U-phase voltage command value V _ua ^* and the V-phase voltage command value V _va ^*. It is done. The three-phase PWM modulation unit 51 generates PWM signals S _u , S _v, and S _w corresponding to the U-phase voltage command value V _ua ^* , the V-phase voltage command value V _va ^*, and the W-phase voltage command value V _wa ^* , respectively. The generated PWM signals S _u , S _v and S _w are output to the motor driver 52. Thereby, voltages V _ua , V _va and V _wa corresponding to the PWM signals S _u , S _v and S _w are applied from the motor driver 52 to the U phase, V phase and W phase of the motor M, respectively. Torque required for steering assistance is generated.

Further, the above-described Patent Document 1 includes an abnormality determination unit 74 for determining whether or not an abnormality such as an offset has occurred, and the abnormality determination unit 74 performs three-phase AC / dq coordinate conversion. Based on the d-axis current detection value i _da and the q-axis current detection value i _qa output from the unit 68, it is determined whether or not an abnormality has occurred. The d-axis current detection value i _da and the q-axis current detection value i _qa are expressed as follows when the amplitudes of the U-phase current detection value i _ua , the V-phase current detection value i _va and the W-phase current detection value i _wa are I _a . It can be shown as the equation (2) and can be understood to be independent of the rotor angle _θre . Therefore, the abnormality determination unit 74 acquires the d-axis current detection value i _da and the q-axis current detection value i _qa regardless of the rotor angle θ _re, and the acquired d-axis current detection value i _da and q-axis current detection value. It is described that the presence or absence of an abnormality can be determined based on i _qa , and that it is not necessary to calculate the effective value of the three-phase current energized to the motor M.

In the above-mentioned Patent Document 1, a specific method of realizing the failure determination, that is, which part of the amplitude I _a , the d-axis current detection value i _da and the q-axis current detection value i _qa is used is completely mentioned. It has not been.

  Accordingly, the present invention has been made in view of the above-described circumstances, and an object thereof is to provide a specific means for easily performing a failure determination of a control system in an electric power steering control device.

  An electric power steering control device according to a first aspect of the present invention includes a dq command value setting means for setting a d-axis current command value and a q-axis current command value in a dq coordinate system as a current to be given to a motor, a motor Current detecting means for detecting the three-phase alternating current actually flowing in the circuit, and converting the three-phase alternating current detected by the current detecting means into a d-axis current detection value and a q-axis current detection value in the dq coordinate system. The three-phase AC / dq coordinate conversion means, the d-axis current command value and the q-axis current command value set by the dq command value setting means, and the three-phase AC / dq coordinate conversion means are output. Based on the d-axis current detection value and the q-axis current detection value, voltage control means for controlling the voltage applied to the motor, and the state where the phase current detection value is outside the first predetermined allowable range If it continues for more than a predetermined time, And a failure determination means for constant, failure determining means, when the sine wave frequency of the three-phase currents and is f, and performs failure determination in the following cycle 1 / 2f.

  The electric power steering control device according to the second invention is determined to be a failure when a state in which the current detection value is outside the first predetermined allowable range within the second predetermined time continues for the first predetermined time or longer. To do.

  The electric power steering control device according to the third aspect of the invention determines the maximum value of the second predetermined time described above that allows failure determination without oversight.

  In the electric power steering control device according to the fourth aspect of the present invention, when at least one of the phase current detection values in a state where no current flows through the energization path provided with the current detection means is outside the second predetermined allowable range. It is determined that a failure has occurred in the control system.

  The electric power steering control device according to the fifth aspect of the invention prohibits failure determination when the rotational speed of the motor is equal to or higher than a predetermined value.

  The electric power steering control device according to the sixth invention stops the motor drive when a failure is detected.

  The electric power steering control device according to the seventh aspect of the invention stops the motor drive by stopping the power supply to the motor drive circuit when a failure is detected.

  The electric power steering control device according to the eighth invention stops the motor drive by stopping the power supply to the pre-driver of the motor drive circuit when a failure is detected.

  The electric power steering control device according to the ninth aspect of the invention stops the motor drive by stopping the power supply to the energization path provided with the current detection means when the failure is detected.

  The electric power steering control device according to the first aspect of the present invention can easily determine the failure of the control system of the electric power steering control device, and if an error such as noise occurs in the phase current detection value, Therefore, the normal operation of the control system can be performed without determining that there is a failure. In addition, by setting the failure determination cycle to 1 / 2f or less, it is possible to prevent erroneous determination of overcurrent caused by continuous detection of an overcurrent state at the peak of the three-phase current.

  The electric power steering control device according to the second aspect of the invention makes it possible to reliably perform a failure determination even when a load current flowing through the motor is in an oscillation state due to a failure such as a ground fault of a wiring to the load. It is.

  In the electric power steering control device according to the third aspect of the present invention, when the sine wave frequency of the phase current detection value is f, the second predetermined time is set to ½ f or less so that it depends on the peak value of the three-phase current. It is possible to prevent erroneous determination of overcurrent.

  The electric power steering control device according to the fourth aspect of the present invention can easily perform failure determination of the control system of the electric power steering control device.

  According to a fifth aspect of the present invention, there is provided an electric power steering control device comprising: a misjudgment due to a regenerative current that flows when a motor is rotated at a high speed from the outside; It is possible to prevent erroneous determination of overcurrent by value.

  The electric power steering control device according to the sixth aspect of the invention can suppress unnecessary power consumption at the time of failure and improve the safety of the electric power steering control device.

  The electric power steering control device according to the seventh aspect of the invention can suppress unnecessary power consumption at the time of failure, and avoids a large current energization that occurs when the input / output terminals of the semiconductor elements constituting the motor drive circuit are short-circuited. Is.

  The electric power steering control device according to the eighth invention can suppress unnecessary power consumption at the time of failure.

  The electric power steering control device according to the ninth aspect of the invention can suppress unnecessary power consumption at the time of failure, and generates unnecessary torque at the time of failure detection by cutting off the power supply line from the motor drive circuit to the motor. It is something to avoid.

Embodiment 1 FIG.
Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a block diagram for explaining a functional configuration of a motor M using an electric power steering control device according to the present invention.
This motor control device includes a target current calculation unit 81 for determining a target torque current command value I ′ _b ^* for generating a steering assist torque by the motor M. In order to improve the steering feeling, The rotor angle θ _re of the motor M detected by the resolver R and the rotor angle detection circuit 45 is used to calculate a convergence correction value I _CO ^* determined from the rotor angular speed ω _re output through the rotor angular speed calculation unit 65 and the vehicle speed V. Then, the convergence correction value is given to the adding unit 62. In the adder 62, the target current command value I ′ _b ^* input from the target current calculator 61 and the convergence correction value I _CO ^* input from the convergence corrector 82 are added together, and the convergence to be given to the motor M is added. Set the corrected torque current command value (q-axis current command value) i _qa ^* . On the other hand, the excitation current command value (d-axis current command value) i _da ^* is set to zero. In FIG. 1, blocks having the same numbers as those in FIG. 15 operate in the same manner as the blocks shown in FIG. Therefore, although detailed description thereof is omitted, the motor driver 52, the three-phase PWM modulation unit 51, the W-phase voltage command value calculation unit 73, the dq / three-phase AC coordinate conversion unit 72, the d-axis current The PI control unit 69d, the q-axis current PI control unit 69q, and the subtraction units 67d and 67q are collectively referred to as voltage control means.

In this embodiment, the target current command value I ′ _b ^* specified by the target current calculation unit 81 and the convergence correction value I _CO ^* are added together by the addition unit 62 and calculated after the convergence correction target current designation value I. _In order to determine whether or not _qa ^* is accurately energized to the motor M, a three-phase current detection value determination unit 101 is installed in the motor control device. Here, in the conventional motor control device proposed in Patent Document 1, two phases of the three-phase current detection value energized to the motor M (U-phase current detection value I _ua and V-phase current detection value I _va ). Is determined on the basis of the detected d-axis current value I _da and the detected q-axis current value I _qa through the three-phase AC / dq coordinate conversion unit 68. The motor control proposed in the first embodiment In the apparatus, the determination is made based on all the phase currents of the detected three-phase current values that are supplied to the motor M. For this purpose, a motor current detector 41 comprising a U-phase current detector 41u that detects a U-phase current, a V-phase current detector 41v that detects a V-phase current, and a W-phase current detector 41w that detects a W-phase current. Is provided.

The three-phase current detection value determination unit 101 uses the U-phase current detection value I _ua and the U-phase current detection value determination unit 101u and the V-phase current detection value I _va for determining a failure of the motor control device. in W-phase current detection value determining unit 101w for using V-phase current detection value determining unit 101v and the W-phase current detection value I _wa for determining a failure of the motor control device determines a failure of the motor control device Composed. When it is detected that at least one of the three-phase current detection values i _ua , i _va , and i _wa input to the three-phase current detection value determination unit 101 is outside a predetermined allowable range, the motor control device It is determined that there is a failure.

Hereinafter, the operation of the detected three-phase current value determination unit 101 will be described with reference to FIGS. 2 and 3.
2 and 3 show a U-phase current detection value I _ua , a V-phase current detection value I _va and a W-phase current detection value I _wa, and a U-phase current detection value I _ua and a V-phase current detection that are supplied to the motor M. The time-phase changes of the U-phase current state flag, the V-phase current state flag, and the W-phase current state flag that indicate the state of the value I _va and the W-phase current detection value I _wa are shown, and the U-phase current detection value i _ua is excessive. The operation when

Here, in order to determine that the U-phase current detection value I _ua is excessive and takes an abnormal value, the U-phase current detection value I _ua is determined to be a normal value as shown in the following equation (3). A predetermined allowable range D ₁ (which takes a range of I _{aMin to} I _aMax ) is set in advance. When the U-phase current detection value I _ua is included in the allowable range D ₁ described above, the U-phase current state flag is set to 0 ′ indicating a normal state, and this motor control device is determined to be normal.

このモータ制御装置に例えばＵ相の電流検出部４１ｕが設けられた通電経路と電源線が短絡する等の故障が発生した場合、図２の時刻Ｔ_ｕ１に示すようにＵ相電流検出値Ｉ_ｕａが最大電流となり、上述した許容範囲Ｄ_１の範囲外となる。そして、その後第１の所定時間Ｔ_ｕ（以下、Ｔ_ｕを故障判定時間と表記）が経過した時刻Ｔ_ｕ２でも継続してＵ相電流検出値Ｉ_ｕａが許容範囲Ｄ_１の範囲外である場合、Ｕ相電流状態フラグが１'に設定されこのモータ制御装置の制御系に故障が発生していると判定される。

When a failure occurs in the motor control device, for example, a short circuit between the power supply path provided with the U-phase current detection unit 41u and the power supply line, the U-phase current detection value I _ua is shown at time T _u1 in FIG. There the maximum current, the outside of the permissible range D ₁ described above. Then, when the U-phase current detection value I _ua continues to be outside the allowable range D ₁ at time T _u2 after which a first predetermined time T _u (hereinafter, T _u is expressed as a failure determination time) has elapsed. The U-phase current state flag is set to 1 ′, and it is determined that a failure has occurred in the control system of this motor control device.

As shown in FIG. 3, even if the U-phase current detection value I _ua falls outside the allowable range D ₁ due to noise such as noise, for example, if the state does not continue for the failure determination time T _u , The current detection value I _ua is determined to be normal, and the U-phase state flag does not change and maintains the state set to 0 ′. By setting the failure determination time _Tu in this manner, even if the U-phase current detection value I _ua fluctuates greatly due to noise or the like and falls outside the allowable range D ₁ , the control system fails. Therefore, the motor control device can continue normal operation.

  Further, by prohibiting failure determination when the motor rotation speed is equal to or higher than a predetermined value, a current value obtained by superimposing a regenerative current generated when the motor is rotated from the outside and a three-phase current supplied to the motor M is superimposed. This makes it possible to prevent erroneous determinations that may occur by making a determination based on the above, and the motor control device can continue normal operation.

4 and 5 show the detected V-phase current detection value I _va , and FIGS. 6 and 7 show the failure determination operation using the detected W-phase current detection value I _wa. Since it is the same as the case of the phase current detection value I _ua , the detailed description is omitted. Furthermore, since the current amplitude value in each phase constituting the three-phase current is the same, the allowable range D _{1 of} each phase current using the minimum allowable three-phase current detection value I _aMin and the maximum allowable three-phase current detection value I _aMax. Can be determined.

FIG. 8 is a detailed electric circuit diagram for explaining functional configurations of the motor driver 52, the controller C, and the motor M described above. The PWM signals S _u , S _v , and S _w output from the controller C form a bridge circuit 52a for controlling the three-phase current that is supplied to the motor M via the pre-driver 52b that the motor driver 52 has. Sent to the base terminal of two semiconductor elements. The bridge circuit 52a, the pre-driver 52b, and the polarized capacitor 52c are supplied with power by the same power source 53, and a switch 54 and a switch 55 are respectively connected to the motor driver 52 to switch the power supply to the motor driver 52. A switch 56 is provided for switching the presence or absence of power supply.

Here, the operation when the short circuit failure occurs in the energization path provided with the U-phase current detection unit 41u will be described with reference to FIG. The target U-phase energization current (hereinafter referred to as target current) to be energized to the motor M determined based on the U-phase voltage value to be given to the motor M by the motor driver 52 has an inclination of the electrical time constant of the motor M. It is determined by τ, and the frequency is a triangular wave with a PWM carrier frequency. Here, if the period of the PWM carrier wave is set sufficiently shorter than τ, the U-phase current detection value I _ua in the normal state is a constant value equal to the target current when t <tx, as shown in FIG. It can be considered. Here, if t = tx and a short-circuit failure occurs in the energization path provided with the U-phase current detection unit 41u, the inductance and resistance viewed from the voltage control means are extremely small at the time of the short-circuit. The U-phase energization current (hereinafter referred to as load current) energizing M increases rapidly, and the U-phase current detection value I _ua is _{equal to} or greater than I _aMax , that is, outside the allowable range D ₁ . The voltage control means then acts to reduce the load current. The load current that decreases with the time constant τ at normal time decreases rapidly because the inductance from the motor driver 52 can be ignored. Accordingly, since the U-phase current detection value I _{ua at} this time is lower than the target current, the voltage control means acts to increase the load current, and the U-phase current detection value I _ua again falls outside the allowable range D ₁ . Since the above operation is repeated, the U-phase current detection value I _ua becomes a constant value (target current) at t = 0 to tx, but when t> tx, as shown in FIG. It becomes a waveform. The U-phase current detection value determination unit 101u included in the controller C sequentially stores determination results for the respective U-phase current detection values I _ua every predetermined cycle T ₁ as shown in FIG. 9A. In the above example, the determination results are all normal (0) when t ≦ tx, and abnormal (1) and normal (0) are repeated when t> tx. Then examine the judgment result in the period T ₃ for each predetermined period T _3, all clear the fault detection counters if it is normal, 1 is added to the failure detection counter otherwise. In the above example, as shown in FIG. 9 (b), the failure detection counter for each t ≦ tx the predetermined period T ₃ is cleared, t> value of the failure detection counter every predetermined period T ₃ in tx is one When the failure detection counter value is non-zero continuously even after the failure determination time _Tu has elapsed from the start of counting of the failure detection counter, it is determined that there is a failure, as shown in FIG. The U-phase current state flag is set to 1.

On the other hand, the operation when the load current temporarily overshoots due to a sudden change in the target current or the like will be described with reference to FIG. For example, when the target current increases from I1 to I2, the voltage control means described above acts to bring the U-phase current closer to the target current I2. When the change width of the target current is small, the U-phase current smoothly increases toward the target current. However, when the change width of the target current is large, the load current increases rapidly, and FIG. Cause overshoot as shown in. However, the U-phase current is reduced by the feedback action of the voltage control means and converges to the target current value. At this time, the determination result sequentially stored in the RAM may become abnormal (1) within the period when the U-phase current detection value I _ua overshoots as shown in FIG. (0). In the above example, as shown in FIG. 10B, all determination results are normal (0) in the next cycle T ₃ (the next period after the overshoot ends) when the failure detection counter becomes 2, The failure detection counter is cleared. Therefore, in this case, it is not determined as a failure, and the U-phase current state flag is not set to 1 as shown in FIG. That, U-phase current detection value determining unit 101u can even be a outside the permissible range D ₁ there are U-phase current, if the condition does not exceed the failure determination time T _u proliferation of U-phase current is a temporary overshoot for such rapid change in the target current, is intended to determine not the current is outside the range of the allowable range D ₁ by the motor short-circuited.
In the above-described embodiment, the failure determination example based on the U-phase current detection value is shown, but the same failure detection can be performed based on the V-phase or W-phase current detection value.

  When it is determined that the control system of the motor control device is out of order, the above-described switch 54, switch 55, and switch 56 are opened (see FIG. 11), whereby the bridge circuit 52a, the predriver 52b, or the motor constituting the motor drive circuit. The power consumption of the motor control device can be suppressed by stopping the power supply to the energization path to M and stopping the driving of the power steering device using the motor. In particular, by opening the switch 54 and stopping the power supply to the bridge circuit 52a, it is possible to avoid a large current flow that occurs when the input / output terminals of the semiconductor elements constituting the bridge circuit 52a are short-circuited. Further, by opening the switch 56 and cutting off the power supply line from the bridge circuit 52a to the motor M, it is possible to avoid generation of unnecessary torque when a failure is detected.

Furthermore, the change of the status flag in the case where the failure determination time T _u set below cycle 1 / 2f of the three-phase currents, will be described with reference to FIG. 12.
For example, in FIG. 12, the failure detection counter is divided into a U-phase current upper limit counter and a U-phase current lower limit counter, and when a value equal to or higher than the upper limit value I _aMax of the allowable range D ₁ is detected, the U-phase current upper limit counter However, when a value equal to or lower than the lower limit value _IaMin is detected, the U-phase current lower limit counter is incremented by one. Since the three-phase current applied to the motor M is a sinusoidal, sets the sine wave frequency of the phase current detection value when is f, the failure determination time T _u below cycle 1 / 2f of the three-phase current (That is, failure determination is performed at a cycle of 1 / 2f or less), even when an overcurrent state at the peak of the three-phase current is detected continuously, both counters can be cleared. Can be prevented in advance.

  Furthermore, by prohibiting the failure determination when the rotational speed of the motor is equal to or higher than a predetermined value, the regenerative current generated when the motor M is rotated from the outside and the three-phase current that is energized to the motor M are superimposed. By making a determination based on the current value, a possible erroneous determination can be prevented, and the motor control device can continue normal operation.

Embodiment 2. FIG.
FIG. 13 is a detailed electric circuit diagram for explaining functional configurations of the motor driver 52, the controller C, and the motor M described above. In this example, a current detection resistor is arranged on the common side of the switching elements connected to the negative side of the DC voltage among the three sets of switching elements constituting the bridge circuit 52a. U-phase current detector 41u and the V-phase current detector 41v as a current detecting means is disposed, W-phase current detection value I _wa is calculated by computation based on the U-phase and V-phase current detection value I _ua and I _va . For example, when the switching element connected to the positive side of the U-phase DC voltage is ON and the switching element connected to the negative side is OFF, no current flows through the current path in which the U-phase current detection resistor is arranged. . If the U-phase current detection value at this time is detected to be outside the scope of the given range D ₂ of 0A vicinity motor control device is determined to be faulty.
Further, when the switching element connected to the positive side of the U-phase DC voltage is OFF and the switching element connected to the negative side is ON, the motor U-phase is provided in the current path in which the U-phase current detection resistor is arranged. The current that flows through the The failure determination described in the first embodiment may be performed based on the U-phase current detection value at this time.
In the above-described embodiment, the failure determination example based on the U-phase current detection value is shown. However, similar failure detection may be performed based on the detected V-phase current detection value or the calculated W-phase current detection value.

It is a block diagram which shows the function structure of the motor control apparatus used for the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows operation | movement of the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows operation | movement of the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows operation | movement of the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows operation | movement of the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows operation | movement of the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows operation | movement of the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship between the motor which controls the electric power steering control apparatus which concerns on Embodiment 1 of this invention, and the controller which controls the motor. It is a timing chart which shows operation | movement of the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows operation | movement of the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows operation | movement of the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows operation | movement of the electric power steering control apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship between the motor which controls the electric power steering control apparatus which concerns on Embodiment 2 of this invention, and the controller which controls the motor. It is a figure which shows the relationship between the motor which controls a general electric power steering control apparatus, and the controller which controls the motor. It is a block diagram which shows the function structure of the conventional electric power steering control apparatus.

Explanation of symbols

  C controller, M motor, R resolver, 41 motor current detector, 41u U phase current detector, 41v V phase current detector, 41w W phase current detector, 42 vehicle speed sensor, 43 torque sensor, 44 phase compensation circuit, 45 Rotor angle detection circuit, 51 Three-phase PWM modulation unit, 52 Motor driver, 52a Bridge circuit, 52b Pre-driver, 52c Polarized capacitor, 61, 81 Target current calculation unit, 64, 82 Convergence value correction unit, 66 q-axis current command Value calculator, 68 three-phase AC / dq coordinate converter, 69d d-axis current PI controller, 69q q-axis current PI controller, 72 dq / three-phase AC coordinate converter, 73 W-phase voltage command value Calculation unit, 101 Three-phase current detection value determination unit, 101u U-phase current detection value determination unit, 101v V-phase current detection value determination unit, 101w W-phase current Detection value determination unit.

Claims (9)

An electric power steering control device for assisting steering by applying torque generated by a motor to a steering mechanism,
D-q command value setting means for setting a d-axis current command value and a q-axis current command value in the dq coordinate system as currents to be given to the motor;
Current detecting means for detecting a phase current that actually flows through the motor;
Three-phase / dq-axis conversion means for converting the phase current detection value detected by the current detection means into a d-axis current detection value in the dq coordinate system and a q-axis current detection value;
The d-axis current command value and the q-axis current command value set by the dq command value setting means, and the d-axis current detection value and the q-axis current detection value output from the three-phase / dq-axis conversion means. Voltage control means for controlling the voltage applied to the motor based on
A failure determination means for determining a failure when the phase current detection value is outside the first predetermined allowable range continues for a first predetermined time or more;
The electric power steering control device, wherein the failure determination means performs failure determination at a cycle of 1 / 2f or less, where f is a sine wave frequency of a three-phase current.   The failure is determined when the state in which the phase current detection value is outside the first predetermined allowable range within the second predetermined time continues for the first predetermined time or longer. Electric power steering control device.   3. The electric power steering control device according to claim 2, wherein the second predetermined time is set to ½ f or less when the sine wave frequency of the three-phase current is f.   4. A failure is determined when a phase current detection value when a current does not flow through an energization path provided with the current detection means is outside a second predetermined allowable range. The electric power steering control device according to any one of the above.   The electric power steering control device according to any one of claims 1 to 4, wherein the failure determination is prohibited when the rotation speed of the motor is equal to or greater than a predetermined value.   The electric power steering control device according to any one of claims 1 to 5, wherein when the failure is determined, the driving of the motor is stopped.   The electric power steering control device according to claim 6, wherein power supply to the motor drive circuit is prohibited when it is determined that there is a failure.   The electric power steering control device according to claim 6, wherein power supply to the pre-driver of the motor drive circuit is prohibited when it is determined that there is a failure.   7. The electric power steering control device according to claim 6, wherein power supply from the motor drive circuit to the motor is prohibited when it is determined that there is a failure.

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