JP6464858B2 - Motor control device and electric power steering device and vehicle equipped with the same - Google Patents

Description

The present invention relates to a motor control device that drives and controls a motor having a multi-system motor winding, and an electric power steering device and vehicle equipped with the motor control device, and in particular, when a failure occurs in any system, the current command value of a normal system The present invention relates to a motor control device that improves a sense of discontinuity of assist by adjusting, and enables smooth handling, an electric power steering device equipped with the motor control device, and a vehicle.

  There is an electric power steering device (EPS) as a device in which a motor is mounted on the drive unit, and the electric power steering device applies a steering assist force (assist force) to the steering mechanism of the vehicle by the rotational force of the motor. A steering assisting force is applied to the steering shaft or the rack shaft by a transmission mechanism such as a gear with a driving force of a motor controlled by electric power supplied from the motor. Such a conventional electric power steering apparatus performs feedback control of the motor current in order to accurately generate the torque of the steering assist force. In feedback control, the motor applied voltage is adjusted so that the difference between the steering assist command value (current command value) and the motor current detection value is small. The adjustment of the motor applied voltage is generally performed by PWM (pulse width). Modulation) is performed by adjusting the duty of the control, and as a motor, a brushless motor that is excellent in durability and maintainability, and has less noise and noise is generally used.

  The general configuration of the electric power steering apparatus will be described with reference to FIG. 1. A column shaft (steering shaft, handle shaft) 2 of the handle 1 is a reduction gear 3 in the reduction unit, universal joints 4a and 4b, a pinion rack mechanism 5, The tie rods 6a and 6b are connected to the steered wheels 8L and 8R via the hub units 7a and 7b. Further, the column shaft 2 is provided with a torque sensor 10 for detecting the steering torque of the handle 1 and a steering angle sensor 14 for detecting the steering angle θ, and the motor 20 for assisting the steering force of the handle 1 is provided with the reduction gear 3. Are connected to the column shaft 2 via The control unit (ECU) 30 that controls the electric power steering apparatus is supplied with electric power from the battery 13 and also receives an ignition key signal via the ignition key 11. The control unit 30 calculates a current command value of an assist (steering assist) command based on the steering torque Ts detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12, and compensates the current command value. The current supplied to the EPS motor 20 is controlled by the voltage control command value Vref subjected to.

  The steering angle sensor 14 is not essential and may not be provided, and the steering angle can be acquired from a rotational position sensor such as a resolver connected to the motor 20.

  The control unit 30 is connected to a CAN (Controller Area Network) 40 that transmits and receives various types of vehicle information, and the vehicle speed Vs can also be received from the CAN 40. The control unit 30 can be connected to a non-CAN 41 that exchanges communications, analog / digital signals, radio waves, and the like other than the CAN 40.

  The control unit 30 is mainly composed of a CPU (including MCU, MPU, etc.). FIG. 2 shows general functions executed by a program inside the CPU.

  The function and operation of the control unit 30 will be described with reference to FIG. 2. The steering torque Ts detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12 (or from the CAN 50) are expressed as a current command value Iref1. The current command value calculation unit 31 to be calculated is input. The current command value calculation unit 31 calculates a current command value Iref1, which is a control target value of the current supplied to the motor 20, using an assist map or the like based on the input steering torque Ts and vehicle speed Vs. The current command value Iref1 is input to the current limiter 33 through the adder 32A, and the current command value Irefm whose maximum current is limited is input to the subtractor 32B, and the deviation I (Irefm) from the fed back motor current value Im. -Im) is calculated, and the deviation I is input to the PI control unit 35 for improving the characteristics of the steering operation. The voltage control command value Vref whose characteristics are improved by the PI control unit 35 is input to the PWM control unit 36, and the motor 20 is PWM driven via an inverter 37 as a drive unit. The current value Im of the motor 20 is detected by the motor current detector 38 and fed back to the subtraction unit 32B. The inverter 37 uses a field effect transistor (FET) as a drive element, and is configured by a bridge circuit of the FET.

  A compensation signal CM from the compensation signal generator 34 is added to the adder 32A, and the compensation of the steering system system is performed by adding the compensation signal CM to improve the convergence and inertia characteristics. . The compensation signal generator 34 adds the self-aligning torque (SAT) 34-3 and the inertia 34-2 by the adder 34-4, and further adds the convergence 34-1 to the addition result by the adder 34-5. The addition result of the adder 34-5 is used as the compensation signal CM.

  In such an electric power steering device, even if a motor failure (including abnormality) occurs, a case where a motor having a multi-system motor winding having a configuration capable of continuing the motor operation is increasing. For example, in a motor having two motor windings, the stator coil is divided into two systems (U1-W1 phase and U2-W2 phase), and even if one system fails, the rotor is rotated by the remaining one system. Thus, the assist control can be continued.

  In a motor control device and an electric power steering device equipped with such a motor, there has been proposed a method for adjusting a current command value when a failure occurs in a motor winding or an inverter. For example, in Japanese Patent Application Laid-Open No. 2013-159165 (Patent Document 1), in an electric power steering apparatus in which two systems of motor coils are provided and each of which is driven and controlled to provide an assist force, a failure has occurred in one of the systems. If this is the case, adjust the current command value so that it is equal to or less than the normal amount of heat generation for the remaining systems, thereby suppressing motor heat generation and continuing assist without lowering the steering feeling. Like to do. Further, in Japanese Patent No. 5338789 (Patent Document 2), when it is determined that an inverter or a winding group has failed in any system in a multi-system electric motor drive device (motor control apparatus), the fault system inverter By cutting off the power supply to the normal system and adjusting the current command value to the normal system (or the input value (feedback current) to the power control means), the power supplied by the faulty system inverter The inverter makes up for it. Then, after a lapse of a certain time from the failure determination, the current command value is adjusted, and the power supplemented by the normal system inverter is gradually reduced to prevent abnormal heat generation.

JP2013-159165A Japanese Patent No. 5387789

  However, in the device disclosed in Patent Document 1, when a failure occurs in any one of the systems, the maximum value of the current command value set in the remaining other system is the calorific value of the remaining other system. A value that is equivalent to the amount of heat generated during normal operation and a value larger than that is not set, so there is a possibility that a gap will occur in the current command value that is set before and after the failure. May be affected. In addition, the details of how to determine a value that is equivalent to the amount of heat generated at normal time are unknown. In the device disclosed in Patent Document 2, when the number of systems is N and the number of systems that have failed is M, the current command value is multiplied by N / (N−M) after failure determination and output to the normal system inverter. Therefore, it is estimated that there is almost no gap between the current command values set before and after the failure. However, the adjustment of the current command value is performed by the multiplication factor, and the adjustment of the current command value in the gradual decrease processing for gradually reducing the power supplemented by the inverter of the normal system is also performed by the multiplication factor or the subtraction of the constant value. The current command value cannot be adjusted flexibly. For example, it is not possible to take measures such as changing the gradual decrease rate of the current command value when the steering torque is small and large.

  The present invention has been made under the circumstances described above, and the object of the present invention is to flexibly adjust the current command value of a normal system when a failure occurs in any system in multi-system motor control. An object of the present invention is to provide a motor control device that improves the discontinuity of assist and enables smooth handling, and an electric power steering device and a vehicle equipped with the motor control device.

The present invention relates to a motor control device for driving and controlling a motor having a multi-system motor winding. The object of the present invention is to provide a motor drive circuit for each winding system for supplying a drive current to a motor having a multi-system motor winding. And a current command value for each winding system for driving the motor, and if a failure occurs in the motor winding or the motor drive circuit of any system, the current command value of the normal system Is changed to a first characteristic that forms a characteristic equivalent to the sum of the current command values under normal conditions, and after performing the first change, there is no steering torque or the steering wheel When the vehicle is in the vicinity of the center or when the vehicle is traveling straight, the motor drive circuit is controlled by performing a second change that changes the characteristic of the current command value to a second characteristic that suppresses the output from the first characteristic. control It is achieved by providing a calculation unit.
The object of the present invention is that the second characteristic is a characteristic in which the gradient is gentler than the first characteristic and changes so as to converge to the maximum output asymptotically in the vicinity of the maximum output, or the current command by property values defined in the assist map, the characteristics of some have the said current command value by a characteristic that varies in response to at least the steering torque, or a failure in the motor winding or the motor drive circuit The system in which this occurs is more effectively achieved by being shut off when a failure occurs.

  By applying the above motor control device to an electric power steering device, it is possible to achieve a highly reliable electric power steering device that improves the discontinuity of assist when a failure occurs and enables smooth handling. By mounting the steering device on the vehicle, the reliability of the vehicle can be further improved.

  According to the motor control device of the present invention, when a failure occurs in any of the systems in the motor control in multiple systems, the characteristics of the current command value is changed to be the same characteristics as before the failure, By transitioning or switching from the current map to the dedicated map at the time of failure, it is possible to improve the discontinuity of assist immediately after the failure, and to reduce fluctuations in steering torque when the assist map is changed.

  Furthermore, according to the electric power steering apparatus equipped with the motor control apparatus according to the present invention, smooth handling is possible, and the steering feeling can be improved by mounting the electric power steering apparatus on a vehicle. .

It is a lineblock diagram showing an outline of an electric power steering device. It is a block diagram which shows the structural example of the control unit (ECU) of an electric power steering apparatus. It is a characteristic view which shows the example of the assist map at the time of normal. It is a characteristic view which shows the example of the assist map at the time of a failure. It is sectional drawing which shows the structural example of the motor which can apply this invention. It is a schematic diagram which shows the winding structure of the motor which can apply this invention. It is a block diagram which shows the structural example (1st Embodiment) of the motor control apparatus which concerns on this invention. It is a block diagram which shows the structural example of the control calculating part of 1st Embodiment. It is a block diagram which shows the structural example of the current control part of 1st Embodiment. It is a characteristic view which shows the example of the assist map which changes gradually with time at the time of a failure. It is a part of flowchart which shows the operation example of the control calculating part of 1st Embodiment. It is a part of flowchart which shows the operation example of the control calculating part of 1st Embodiment. It is a part of flowchart which shows the operation example of the control calculating part of the structural example (2nd Embodiment) of the motor control apparatus which concerns on this invention. It is a block diagram which shows the structural example of the control calculating part of the structural example (3rd Embodiment) of the motor control apparatus which concerns on this invention.

  In the present invention, when a failure (including abnormality) occurs in a motor drive circuit including a motor winding having a multi-system motor winding or an inverter, a current command that is a control target value of a current supplied to the motor Change the characteristic of the value so that it is equivalent to the characteristic before the failure, and after that change, further change the characteristic to suppress the output. For example, there are two motor windings, and an assist map of current command values used in each system (hereinafter referred to as “system-specific assist map”) changes according to the steering torque as shown by the solid line in FIG. In the case of the characteristic, the two systems control the motor with the same output at normal time, so the assist map of the entire current command value (hereinafter referred to as “total assist map”) is as shown by the broken line in FIG. Characteristic (hereinafter referred to as “overall characteristic”). In this situation, if a failure occurs in any of the systems, the system-specific assist map is changed so that the system-specific assist map of the normal system has a characteristic (first characteristic) that forms an overall characteristic. . In brief, the entire assist map is used as an assist map for each normal system. Thereby, the influence of the gap of the current command value before and after the failure is reduced, and the discontinuity of assist can be improved. However, the maximum value of the first characteristic exceeds the maximum output per system during normal operation (hereinafter simply referred to as “maximum output”). If the first characteristic remains unchanged, the load on the motor winding is heavy. Therefore, after changing to the first characteristic so that the maximum value of the first characteristic does not exceed the maximum output, the system-specific assist map is changed to the characteristic (second characteristic) as shown by the solid line in FIG. change. The second characteristic is a characteristic in which the maximum value is equal to or less than the maximum output, the gradient is gentler than that of the first characteristic, and changes so as to converge asymptotically to the maximum output near the maximum output. However, if the second characteristic is suddenly changed, the assist force suddenly becomes weak and the steering feeling may be lowered. Therefore, the characteristic is gradually changed as time elapses. Thereby, since the fluctuation | variation of the steering torque at the time of assist map change is relieved, a steering person becomes difficult to take a steering wheel.

  The change to the second characteristic may be performed not under gradual change with time but under a steering condition or traveling condition in which the current command value is minimized. For example, by changing to the second characteristic when there is no steering torque to the steering wheel, it is possible to suppress the influence of fluctuations in the motor assist force perceived by the steering operator before and after the assist map is changed.

  The current command value can be calculated not only based on the steering torque but also based on the vehicle speed, the motor rotation speed, and the like. For example, the assist map shown in FIG. 3 can be prepared for each of low speed, medium speed, and high speed. The assist map may be prepared as a look-up table, or may be defined as a function with steering torque as a variable. When prepared as a lookup table, the current command value calculation can be speeded up, and when defined as a function, the area for storing the assist map can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, an example of a dual winding motor to which the present invention can be applied will be described with reference to FIGS. Although the present invention is an electric motor, it will be described below simply as a “motor”.

  As shown in FIG. 5, the three-phase motor 200 has a stator 12S having teeth T that are formed inwardly on the inner peripheral surface and serve as magnetic poles forming slots SL, and teeth T on the inner peripheral side of the stator 12S. It has a configuration of an SPM (Surface Permanent Magnet) motor having an 8-pole surface magnet type rotor 12R on the surface of which permanent magnets PM are arranged so as to be rotatable in opposition to each other. Here, the number of teeth T of the stator 12S is set to the number of phases × 2n (n is an integer equal to or larger than 2), for example, n = 2, and is configured to have 8 poles and 12 slots.

  Then, in the slot SL of the stator 12S, the first three-phase motor winding L1 and the second three-phase motor winding L1 and the second phase shown in FIG. Two three-phase motor windings L2 are wound. In the first three-phase motor winding L1, one end of the U-phase coil U1, V-phase coil V1, and W-phase coil W1 is connected to each other to form a star connection, and the other end of each phase coil U1, V1, and W1 is the motor. The motor drive currents I1u, I1v, and I1w are individually supplied to the control device 100.

  Two coil portions U1a, U1b, V1a, V1b and W1a, W1b are formed in each phase coil U1, V1 and W1. These coil portions U1a, V1a and W1a are wound in concentrated winding on teeth T10, T2 and T6 whose positions form an equilateral triangle. In addition, the coil portions U1b, V1b, and W1b are wound in concentrated winding on the teeth T1, T5, and T9 that are respectively moved by 90 ° clockwise from the teeth T10, T2, and T6.

  The second three-phase motor winding L2 is connected to one end of a U-phase coil U2, a V-phase coil V2, and a W-phase coil W2 to form a star connection, and the other end of each phase coil U2, V2, and W2 Are connected to the motor control device 100, and motor drive currents I2u, I2v and I2w are individually supplied.

  Two coil portions U2a, U2b, V2a, V2b and W2a, W2b are formed in each phase coil U2, V2, and W2. These coil portions U2a, V2a and W2a are wound in concentrated winding on teeth T4, T8 and T12 whose positions form an equilateral triangle. The coil portions U2b, V2b, and W2b are wound in concentrated winding on the teeth T7, T11, and T3 that are respectively moved 90 ° clockwise from the teeth T4, T8, and T12.

  The coil portions U1a, U1b, V1a, V1b and W1a, W1b of each phase coil U1 to W1 and the coil portions U2a, U2b, V2a, V2b and W2a, W2b of each phase coil U2 to W2 sandwich each tooth T. The slot SL is wound so that the direction of the energization current is the same.

  Thus, the coil portions U1a, U1b, V1a, V1b and W1a, W1b of the respective phase coils U1 to W1 of the first three-phase motor winding L1, and the respective phase coils U2 to U2 of the second three-phase motor winding L2. W2 coil portions U2a, U2b, V2a, V2b and W2a, W2b are wound around 12 different teeth.

  An OFF fault (open fault) or an ON fault (short fault) that supplies current from an individual inverter to the switching means of one of the inverters for such a three-phase motor having two systems of windings, becomes impossible. The configuration of the motor control device according to the present invention that controls the switching means excluding the fault switching means and controls the normal inverter other than the faulty inverter including the fault switching means when the fault occurs. An example (first embodiment) will be described with reference to FIG.

The motor control device 100 includes a failure detection unit 111, and a control calculation unit 110 that calculates a current command value, and voltage command values (voltage control command values) V1 ^* and V2 ^* output from the control calculation unit 110 are individually input. Motor drive circuits 120A and 120B, and motors interposed between the output sides of the motor drive circuits 120A and 120B and the first motor winding L1 and the second motor winding L2 of the three-phase motor 200 Current interruption circuits 130A and 130B are provided.

  The three-phase motor 200 includes a rotational position sensor 101 such as a Hall element that detects the rotational position of the rotor. A detection value from the rotational position sensor 101 is input to the motor rotational angle detection circuit 102, and the motor rotational angle detection circuit is detected. The motor rotation angle θm is detected at 102, the motor rotation angle θm is input to the motor rotation number calculation unit 105, and the motor rotation number calculation unit 105 calculates the motor rotation number ω. The control calculation unit 110 receives the steering torque Ts detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12, and the motor rotation angle θm and motor rotation output from the motor rotation angle detection circuit 102. The motor rotation speed ω output from the number calculation unit 105 is input. Further, motor currents I1d output from the respective phase coils of the first motor winding L1 and the second motor winding L2 of the motor 200 output from the current detection circuits 121A and 121B in the motor drive circuits 120A and 120B, and I2d is input to the control calculation unit 110. Further, a direct current is supplied to the motor drive circuits 120A and 120B from the battery 103 as a direct current power source through the noise filter 104.

The control calculation unit 110 calculates the current command value I ^* by referring to the assist map based on the steering torque Ts, the vehicle speed Vs, and the motor rotation speed ω.

FIG. 8 shows a configuration example of the control calculation unit 110. The control calculation unit 110 includes a torque control unit 112, current control units 113A and 113B, and a failure detection unit 111. The torque control unit 112 calculates a current command value I ^* with reference to the assist map based on the steering torque Ts, the vehicle speed Vs, and the motor rotation speed ω, and outputs the current command value I ^* to the current control units 113A and 113B.

The torque control unit 112 uses an assist map having characteristics as indicated by a solid line in FIG. 3 (hereinafter referred to as a “normal assist map”) as a system-specific assist map. The current command value I ^* is calculated using a plurality of assist maps having characteristics as shown in FIG. That is, when a failure occurs, an assist map (hereinafter referred to as “first characteristic assist map”) having characteristics (first characteristics) equivalent to the overall assist map as shown by the broken line in FIG. 10 is used. Is switched to an assist map having characteristics as shown by a one-dot chain line in FIG. 10 (hereinafter referred to as a “gradual change assist map”) at predetermined time intervals in the order of A, B, and C, and finally in FIG. An assist map having characteristics (second characteristics) as indicated by a solid line (hereinafter referred to as “second characteristic assist map”) is used. In this configuration example, three gradual change assist maps are used. However, the number of gradual change assist maps to be used may be arbitrarily determined, and the switching time interval may be arbitrarily determined. The time interval for switching from the first characteristic assist map to the gradually changing assist map and the time interval for switching between the gradually changing assist maps may be the same or different. The characteristics of the system-specific assist map indicated by the solid lines in FIGS. 3 and 10 are expressed using only the steering torque Ts as a variable, but the current command value I ^* is also added to the vehicle speed Vs and the motor rotation speed ω in addition to the variables. It may be calculated.

A configuration example of the current control unit 113A is shown in FIG. The current control unit 113A includes a dq-axis current command value calculation unit 114A, a two-phase / three-phase conversion unit 115A, and a voltage command value calculation unit 116A. The dq-axis current command value calculation unit 114A is configured to determine the d-axis current command value Id ^* and the q-axis current in the dq coordinate system of the vector control based on the current command value I ^* , the motor rotation angle θm, and the motor rotation speed ω. Command value Iq ^* is calculated. The two-phase / three-phase converter 115A converts the calculated d-axis current command value Id ^* and q-axis current command value Iq ^* into two-phase / three-phase according to the motor rotation angle θm, thereby converting the U-phase current command value I1u ^* , V-phase current command value I1v ^* and W-phase current command value I1w ^* are calculated. The voltage command value calculation unit 116A outputs the calculated U-phase current command value I1u ^* , V-phase current command value I1v ^*, W-phase current command value I1w ^* and the motor current I1d detected by the current detection circuit 121A for each phase. Current deviations ΔIu, ΔIv, and ΔIw with the added value are calculated, and PI control calculation is performed on these current deviations ΔIu, ΔIv, and ΔIw to calculate and calculate a three-phase voltage command value V1 ^* for the motor drive circuit 120A. The three-phase voltage command value V1 ^* is output to the motor drive circuit 120A. The U-phase current command value I1u ^* , the V-phase current command value I1v ^*, and the W-phase current command value I1w ^* calculated by the two-phase / three-phase conversion unit 115A are also output to the failure detection unit 111.

The current control unit 113B has the same configuration as the current control unit 113A, and uses the current command value I ^* , the motor rotation angle θm, the motor rotation number ω, and the motor current I2d detected by the current detection circuit 121B, to the motor drive circuit 120B. The three-phase voltage command value V2 ^* is calculated, and the calculated three-phase voltage command value V2 ^* is output to the motor drive circuit 120B. The U-phase current command value I2u ^* , the V-phase current command value I2v ^*, and the W-phase current command value I2w ^* calculated by the current control unit 113B are also output to the failure detection unit 111. The three-phase voltage command values V1 ^* and V2 ^* are output as the same value when the motor control device 100 is operating normally.

The failure detection unit 111 includes a U-phase current command value I1u ^* , a V-phase current command value I1v ^{*, a} W-phase current command value I1w ^* , a U-phase current command value I2u ^* , a V-phase current command value I2v ^*, and a W-phase current. In addition to the command value I2w ^* , motors detected by failure detection circuits 131A and 131B provided between the motor current cutoff circuits 130A and 130B and the first motor winding L1 and the second motor winding L2 of the motor 200 Current detection values I1ud, I1vd, I1wd and I2ud, I2vd, I2wd are input. The failure detection unit 111 configures inverters 122A and 122B by comparing the input motor current detection values I1ud to I1wd and I2ud to I2wd with the phase current command values I1u ^{* to} I1w ^* and I2u ^{* to} I2w ^* , respectively. Open faults (OFF faults) and short-circuit faults (ON faults) of field effect transistors (FETs) Q1 to Q6 as switching elements are detected. Then, when an open failure or a short failure of the FETs constituting the inverters 122A and 122B is detected, a failure system cutoff command SAa or SAb is issued to the gate drive circuit 123A or 123B of the motor drive circuit 120A or 120B that has detected the failure. The current command value change command ISW is output to the torque control unit 112.

Each of the motor drive circuits 120A and 120B receives the three-phase voltage command values V1 ^* and V2 ^* output from the control calculation unit 110 to form a gate signal, and also serves as a failure current control unit. 123A and 123B, and inverters 122A and 122B to which gate signals output from the gate drive circuits 123A and 123B are input.

When the voltage command values V1 ^* and V2 ^* are input from the control calculation unit 110, the gate driving circuits 123A and 123B each have six PWMs based on the voltage command values V1 ^* and V2 ^* and a triangular wave carrier signal. A signal (gate signal) is formed, and these PWM signals are output to inverters 122A and 122B.

  Further, the gate drive circuit 123A outputs three high-level gate signals to the motor current cut-off circuit 130A and the power cut-off when the failure system cut-off command SAa is not normally input from the control calculation unit 110. Two high-level gate signals are output to the circuit 124A, and when the failure is the failure system cutoff command SAa, three low-level gate signals are simultaneously output to the motor current cutoff circuit 130A. The motor current is cut off, and two low level gate signals are simultaneously output to the power cut-off circuit 124A to cut off the battery power.

  Similarly, the gate drive circuit 123B outputs three high-level gate signals to the motor current cutoff circuit 130B and outputs power to the motor current cutoff circuit 130B when the failure system cutoff command SAb is not input from the control calculation unit 110. Two high-level gate signals are output to the cut-off circuit 124B, and when the failure is caused by the failure system cut-off command SAb, three low-level gate signals are simultaneously output to the motor current cut-off circuit 130B. The motor current is cut off, and two low level gate signals are simultaneously output to the power cut-off circuit 124B to cut off the battery power.

  Each of the inverters 122A and 122B receives the battery current of the battery 103 via the noise filter 104 and the power cutoff circuits 124A and 124B, and is connected to smoothing electrolytic capacitors CA and CB on the input side.

  The inverters 122A and 122B have FETs Q1 to Q6 as six switching elements, and three switching arms in which two FETs are connected in series (SAu, SAv and SAw in the inverter 122A, SBu, SBv and SBw in the inverter 122B). ) Are connected in parallel. The PWM signals output from the gate drive circuits 123A and 123B are input to the gates of the FETs Q1 to Q6, so that the U-phase currents I1u, I2u and the V-phase currents that are motor drive currents between the FETs of the switching arms. I1v, I2v and W-phase currents I1w, I2w are input to the first winding L1 and the second winding L2 of the motor 200 via the motor current cutoff circuits 130A and 130B.

  The current detection circuits 121A and 121B in the motor drive circuits 120A and 120B have a voltage across the shunt resistor inserted between the switching arms of the inverters 122A and 122B and the ground, although not shown in FIG. The motor currents I1d and I2d are detected as input.

  The motor current cutoff circuit 130A has three current cutoff FETs QA1, QA2, and QA3, and the motor current cutoff circuit 130B has three current cutoff FETs QB1, QB2, and QB3. The FETs QA1 to QA3 and QB1 to QB3 of the motor current cutoff circuits 130A and 130B are connected in the same direction with the cathodes of the respective parasitic diodes being the inverters 122A and 122B.

  Each of the power cutoff circuits 124A and 124B has a series circuit configuration in which two FETs QC1, QC2 and QD1, QD2 connect the drains and the parasitic diodes are reversed. The sources of the FETs QC1 and QD1 are connected to each other and connected to the output side of the noise filter 104, and the sources of the FETs QC2 and QD2 are connected to the sources of the FETs Q1, Q2, and Q3 of the inverters 122A and 122B.

  An operation example of such a configuration will be described.

  When the operation starts, the motor rotation angle detection circuit 102 detects the motor rotation angle θm of the motor 200 and outputs it to the motor rotation number calculation unit 105 and the current control units 113A and 113B of the control calculation unit 110.

  The motor rotation number calculation unit 105 calculates the motor rotation number ω from the motor rotation angle θm and outputs it to the torque control unit 112 and the current control units 113A and 113B of the control calculation unit 110.

  An operation example of the control calculation unit 110 will be described with reference to the flowcharts of FIGS. 11 and 12.

The torque control unit 112 inputs the motor rotation speed ω, the steering torque Ts detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12, and calculates the current command value I ^* using the assist map (step) S10).

In calculating the current command value I ^* , it is first checked whether or not a current command value change command ISW is input (step S110). If the current command value change command ISW is not input, the failure of the FET constituting the inverters 122A and 122B has not been detected, and the current command value I ^* is calculated using the normal assist map ( Step S120). If the current command value change command ISW has been input, it means that a failure has been detected, and the assist command is switched according to the elapsed time since the input, and the current command value I ^* is calculated. That is, if it is immediately after the input of the current command value change command ISW (step S130), the current command value I ^* is calculated by switching to the first characteristic assist map (step S140). If not immediately after the input of the current command value change command ISW (step S130), the current command value I ^* is calculated by switching to the gradual change assist map in order as the predetermined time interval elapses (step S150). When all the gradual change assist maps are used (step S160), the current command value I ^* is calculated by switching to the second characteristic assist map (step S170). Thereafter, the current command value I ^* is calculated using the second characteristic assist map as it is.

The calculated current command value I ^* is input to the current control unit 113A and the current control unit 113B of the control calculation unit 110.

In the current control unit 113A, the current command value I ^* , the motor rotation angle θm, and the motor rotation number ω are input to the dq-axis current command value calculation unit 114A. The dq-axis current command value calculation unit 114A calculates a d-axis current command value Id ^* and a q-axis current command value Iq ^* based on the current command value I ^* , the motor rotation angle θm, and the motor rotation speed ω, Output to phase / 3-phase converter 115A. The 2-phase / 3-phase converter 115A converts the d-axis current command value Id ^* and the q-axis current command value Iq ^* into two-phase / three-phase according to the motor rotation angle θm, thereby converting the U-phase current command value I1u ^* , A command value I1v ^* and a W-phase current command value I1w ^* are calculated. The phase current command values I1u ^* , I1v ^* and I1w ^* are output to the voltage command value calculation unit 116A and the failure detection unit 111. The voltage command value calculation unit 116A calculates current deviations ΔIu, ΔIv, and ΔIw between the phase current command values I1u ^* , I1v ^*, and I1w ^* and the addition value for each phase of the motor current I1d detected by the current detection circuit 121A. Then, PI control calculation or PID control calculation is performed on the calculated current deviations ΔIu, ΔIv, and ΔIw to calculate the voltage command value V1 ^* and output it to the motor drive circuit 120A (step S20).

The current control unit 113B also operates in the same manner as the current control unit 113A, using the current command value I ^* , the motor rotation angle θm, the motor rotation speed ω, and the motor current I2d, so that each phase current command value I2u ^* , I2v ^* and The I2w ^{* and the} voltage command value V2 ^* are calculated, and the phase current command values I2u ^* , I2v ^* and I2w ^* are output to the failure detection unit 111, and the voltage command value V2 ^* is output to the motor drive circuit 120B (step S30). ).

Phase current command value ^{I1u *,} I1v * and I1w ^* and ^{I2u *,} I2v * and I2w ^* failure detector 111 enter the fault detection circuit 131A and the motor current detection value I1ud detected in 131B, I1vd and I1wd In addition, I2ud, I2vd, and I2wd are also input, and an open fault or a short fault of the FETs constituting the inverters 122A and 122B is detected. When a failure is detected by comparing each phase current command value I1u ^* , I1v ^* and I1w ^* with the motor current detection value I1ud, I1vd and I1wd (step S40), a fault system shutoff command SAa is output to the motor drive circuit 120A ( Step S50). When a failure is detected by comparing each phase current command value I2u ^* , I2v ^* and I2w ^* with the motor current detection value I2ud, I2vd and I2wd (step S60), a fault system shutoff command SAb is output to the motor drive circuit 120B ( Step S70). If a fault system shutoff command SAa or / and SAb is output (step S80), that is, if a fault is detected in one or both of the inverters 122A and 122B, a current command is sent to the torque control unit 112. A value change command ISW is output (step S90). This current command value change command ISW is used for condition determination in step S110.

In the motor drive circuit 120A, if the voltage command value V1 ^* is input to the gate drive circuit 123A and the failure detection unit 111 outputs the failure system cutoff command SAa, the failure system cutoff command SAa is also input to the gate drive circuit 123A. . When the voltage command value V1 ^* is input, the gate drive circuit 123A forms six PWM signals based on the voltage command value V1 ^* and the triangular wave carrier signal, and outputs the PWM signals to the inverter 122A. When the failure system shutdown command SAa is not input, the gate drive circuit 123A outputs a high level gate signal to the motor current cutoff circuit 130A and the power cutoff circuit 124A. As a result, the FETs QA1, QA2, and QA3 of the motor current cutoff circuit 130A are turned on, the conductive state is established between the inverter 122A and the first winding L1 of the motor 200, and the FETs QC1 and QC2 of the power cutoff circuit 124A are turned on. In this state, the direct current from the battery 103 is supplied to the inverter 122A via the noise filter 104. Therefore, the PWM signal output from the gate drive circuit 123A is input to the gates of the FETs Q1 to Q6 of the inverter 122A, and the U-phase current I1u, the V-phase current I1v, and the W-phase current from between the FETs of the switching arms SAu, SAv, and SAw. I1w is input to the first winding L1 of the motor 200. When the failure system cutoff command SAa is input, the gate drive circuit 123A outputs a low-level gate signal to the motor current cutoff circuit 130A and the power cutoff circuit 124A. As a result, the FETs QA1, QA2, and QA3 of the motor current cut-off circuit 130A are turned off, the energization to the first winding L1 of the motor 200 is cut off, and further, the FETs QC1 and QC2 of the power cut-off circuit 124A are turned off. Is cut off from the direct current supply to the inverter 122A.

  Also in the motor drive circuit 120B, each phase current input to the second winding L2 of the motor 200 is controlled by the same operation as the motor drive circuit 120A.

  As described above, according to the first embodiment, when a failure is detected, the current command value is calculated by switching the system-specific assist map to the first characteristic assist map, so that the discontinuity of assist can be improved. And after that, gradually switching to the gradual change assist map eases the discontinuity of the assist, and finally, the gradient of the change with respect to the steering torque is gradual, and it is characterized by mathematically smooth saturation up to the maximum output. Since the current command value is calculated by switching to the second characteristic assist map, smooth handling can be realized in which the steering torque increases smoothly as the load increases.

  In the first embodiment, the change from the first characteristic to the second characteristic is performed using the gradual change assist map, but is performed by a method that decreases the current command value at a constant rate. May be. For example, when the change from the first characteristic to the second characteristic is performed in the K stage (K is an integer of 2 or more), the current command value Ik used in the k stage (k is an integer of 1 or more and less than K) Assuming that the current command value based on the first characteristic assist map is If and the current command value based on the second characteristic assist map is Is, it is calculated as Ik = If−k × (If−Is) / K. Thereby, the area | region which memorize | stores a gradual change assist map can be reduced.

Further, in the torque control unit 112 of the first embodiment, the characteristics of the steering system may be compensated to improve the convergence property, the inertia property, and the like. For example, a convergence compensation value that compensates for the convergence of the yaw rate is calculated based on the motor rotational speed (motor angular velocity) ω, and the torque generated by the inertia of the motor 200 based on the motor angular acceleration α calculated from the motor rotational speed ω. A torque compensation value that compensates for an equivalent amount to prevent the deterioration of the inertial feeling or control responsiveness is calculated, and an SAT compensation value that compensates the assist force of the motor 200 is calculated based on the estimated or detected SAT. The characteristic is compensated by adding the value to the current command value I ^* .

  Furthermore, although each phase current command value is calculated individually, the one-phase current command value may be calculated based on the total value of the other two-phase current command values. Thereby, the amount of calculation can be reduced.

  The change from the first characteristic to the second characteristic can be performed not by gradual change with time as in the first embodiment but by the steering condition and the traveling condition. For example, the timing when the current command value becomes minimum, such as “when there is no steering torque”, “when the steering wheel is near the center”, “when the vehicle is moving straight”, “when the vehicle is stopped”, etc. The system-specific assist map is switched from the first characteristic assist map to the second characteristic assist map.

  A configuration example (second embodiment) in the case of changing from the first characteristic to the second characteristic in accordance with the steering condition and the traveling condition is the same configuration as the first embodiment, and calculates the current command value of the torque control unit. The operation of is different. The torque control unit in the second embodiment uses the normal assist map, the first characteristic assist map, and the second characteristic assist map as the system-specific assist maps. When normal, the normal assist map is used, and when a failure occurs, the first characteristic assist map is used. When the above-mentioned steering conditions or travel conditions (hereinafter collectively referred to as “switching conditions”) are satisfied for the first time after the failure occurs Uses the second characteristic assist map. After that, the current command value is calculated by continuing to use the second characteristic assist map.

  An example of the operation of calculating the current command value of the torque control unit in the second embodiment will be described with reference to the flowchart of FIG.

First, it is confirmed whether or not a current command value change command ISW is input (step S111). If the current command value change command ISW is not input, the failure of the FET constituting the inverters 122A and 122B has not been detected, and the current command value I ^* is calculated using the normal assist map ( Step S121). If the current command value change command ISW has been input, it means that a failure has been detected, and the current command value I ^* is calculated by switching the assist map. That is, if it is immediately after the input of the current command value change command ISW (step S131), the current command value I ^* is calculated by switching to the first characteristic assist map (step S141). If it is not immediately after the input of the current command value change command ISW (step S131), it is confirmed whether or not it has been switched to the second characteristic assist map (step S151), and if it has not been switched, the running state and the steering state are detected. (Step S161) If the switching has been completed, the current command value I ^* is calculated using the second characteristic assist map (Step S191). If it has been switched to the second characteristic assist map, the switching condition has already been satisfied and there is no need to switch the system-specific assist map, so it is confirmed whether or not the switch has been made before detecting the running state and the steering state. is there. If the traveling state and the steering state are detected, it is confirmed whether or not the detected traveling state and the steering state satisfy the switching condition (step S171). If the switching condition is satisfied, the system-specific assist map is set to the second characteristic. Switching to the assist map (step S181), the current command value I ^* is calculated (step S191). If the switching condition is not satisfied, the current command value I ^* is continuously calculated using the first characteristic assist map (step S141). After switching to the second characteristic assist map, the current command value I ^* is calculated using the second characteristic assist map as it is.

  As described above, according to the second embodiment, it is possible to switch the assist map for each system while suppressing the influence of the fluctuation of the motor assist force perceived by the steering operator before and after the assist map change.

  Although the control calculation unit of the first embodiment includes two current control units, the current calculation unit may be integrated into one. By combining them into one, the apparatus can be made compact.

FIG. 14 shows a block diagram of a configuration example (third embodiment) of the motor control device according to the present invention in which one current control unit of the control calculation unit is combined. Compared with the control calculation unit 110 of the first embodiment shown in FIG. 8, the control calculation unit 310 of the third embodiment has one current control unit. The current control unit 313 outputs voltage command values V1 ^* and V2 ^*, and outputs phase current command values I1u ^* , I1v ^* and I1w ^* and I2u ^* , I2v ^* and I2w ^* . The motor currents I1d and I2d output from the motor drive circuits 120A and 120B are input to the current control unit 313.

The operation of the third embodiment is the same as that of the first embodiment except for the operation of the current control unit 313. The operation of the current control unit 313 is a combination of the operation of the current control unit 113A and the operation of the current control unit 113B of the first embodiment. That is, the current control unit 313 includes the current command value I ^* output from the torque control unit, the motor rotation angle θm output from the motor rotation angle detection circuit 102, the motor rotation number ω output from the motor rotation number calculation unit, and the motor drive circuit. The motor current I1d output from 120A and the motor current I2d output from the motor drive circuit 120B are input, and Steps S20 and S30 in the flowchart shown in FIG. 11 are executed, and the voltage command values V1 ^* and V2 ^* Command values I1u ^* , I1v ^* , I1w ^* , I2u ^* , I2v ^* and I2w ^* are output.

  In the above-described embodiments (first to third embodiments), a three-phase motor having two-system motor windings has been described. However, the present invention can be similarly applied to a motor having three or more system motor windings. It can also be applied to multi-phase motors with more than one phase. When applied to a motor having M system motor windings (M is an integer of 3 or more), when m motor windings (m is an integer of 1 or more and less than M) have failed, (M−m) Since the overall characteristic is formed by the system-specific assist map of each normal system, for example, the first assist map is obtained by multiplying the overall assist map by 1 / (M−m) times.

  Further, in the above-described embodiment, the failure to be detected is targeted for the failure of the inverter of the motor drive circuit, but the present invention can also be applied when the motor winding fails. The coil connection method is star connection, but delta connection may be used.

1 Handle 2 Column shaft (steering shaft, handle shaft)
10 Torque sensor 12 Vehicle speed sensor 14 Rudder angle sensor 20 Motor 30 Control unit (ECU)
DESCRIPTION OF SYMBOLS 100 Motor control apparatus 101 Rotation position sensor 102 Motor rotation angle detection circuit 103 Battery 104 Noise filter 105 Motor rotation speed calculation part 110, 310 Control calculation part 111 Failure detection part 112 Torque control part 113A, 113B, 313 Current control part 114A dq-axis current command value calculation unit 115A 2-phase / 3-phase conversion unit 116A voltage command value calculation units 120A, 120B motor drive circuits 121A, 121B current detection circuits 122A, 122B inverters 123A, 123B gate drive circuits 124A, 124B Circuits 130A and 130B Motor current cut-off circuits 131A and 131B Fault detection circuit 200 Dual winding motor

Claims (7)

A motor drive circuit for each winding system for supplying a drive current to a motor having a multi-system motor winding;
A current command value for each winding system for driving the motor is calculated, and if a failure occurs in the motor winding or the motor drive circuit of any system, the characteristics of the current command value of the normal system Is changed to a first characteristic that forms a characteristic equivalent to the sum of the current command values under normal conditions, and after performing the first change, there is no steering torque or the steering wheel is near the center. Control calculation for controlling the motor drive circuit by performing a second change that changes the characteristic of the current command value to a second characteristic that suppresses the output from the first characteristic when the vehicle is traveling straight or when the vehicle is traveling straight ahead A motor control device.   2. The motor control device according to claim 1, wherein the second characteristic is a characteristic that has a gentler slope than the first characteristic and changes asymptotically converges to the maximum output in the vicinity of the maximum output.   The motor control device according to claim 1, wherein the characteristic of the current command value is defined by an assist map. Characteristics of the current command value, the motor control device according to any one of claims 1 to 3 is a characteristic that varies in response to at least the steering torque. The motor control device according to any one of claims 1 to 4 , wherein a system in which a failure has occurred in the motor winding or the motor drive circuit is shut off when a failure occurs. Claimed is the motor drive control by a motor control device according to any one of claim 1 to 5, the electric power steering device for providing assist force to a steering system of the vehicle. A vehicle equipped with the electric power steering device according to claim 6 .