JP2003088163A - Drive unit for brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge, in an electric power assisting power steering device using a three-phase brushless motor, a direction of motor rotation (a direction of torque) through simple circuitry and a faulty device if steering is reversely assisted. SOLUTION: A torque direction computing portion 21 determines a direction of torque based on a signal from a torque sensor 7. A bit transposing portion 25 transposes three bits in the three-bit output data of a position sensor 22 which detects the position of a magnet rotor and the three-bit output data of an upper FET drive signal output portion 24 for FETs in bridge connection, so that these pieces of the three-bit output data are not arranged in the same phase, and both the pieces of three-bit data and ANDed by a driving direction judging portion 23. If the AND condition holds at any bit of the three bits, it is judged that the rotation is in one direction. If the AND condition does not hold at every bit, it is judged that the rotation is in the other direction. If the rotational direction judged by the driving direction judging portion 23 is not matched with the above direction of torque, that is judged as an anomaly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor driving device capable of discriminating the driving direction of a brushless motor with a simple circuit structure. The present invention relates to a device capable of preventing reverse assist when used as an assist motor of an electric power steering device that generates a.

[0002]

2. Description of the Related Art Generally, an electric power steering system is constructed as shown in FIG. In FIG. 5, the steering wheel 1 is a first steering shaft 2a.
And is connected to the second steering shaft 2b via the universal joint 3.

The second steering shaft 2b is
It is connected to a tie rod 6 of a steering wheel via a pinion 4 and a rack 5. Second steering shaft 2
A torque sensor 7 for detecting the steering torque of the steering wheel 1 is provided at b, and an assist motor 8 for assisting the steering force of the steering wheel 1 is coupled to the second steering shaft 2b via a reduction gear 9.
Reference numeral 10 denotes a vehicle state detection device that detects a running state of the vehicle such as engine speed, vehicle speed, and steering wheel load by a sensor.

Reference numeral 11 denotes a motor drive current (target current command value) from the detection output of the vehicle state detection device 10, the detection torque of the torque sensor 7, the detection current obtained from a current detector (not shown), a voltage detector, detection voltage, etc. ) Is obtained and the current supplied to the assist motor 8 is controlled based on the target current command value, and is composed of, for example, a microcomputer.

Reference numeral 12 is a relay which is turned on by turning on a key switch of an ignition key and is turned off, for example, in case of a malfunction. The controller 11 and the assist motor 8 are driven by the power source of the battery 13 supplied via the relay 12.

In the apparatus constructed as described above, the motor drive control section of the controller 11 drives the assist motor 8 to add the assist torque to the steering torque to improve the operability of the steering wheel 1.

At this time, in order to prevent the assist motor 8 from being driven (that is, reverse assist) in the direction opposite to the steering assist direction (steering torque detection direction of the torque sensor 7) due to the influence of external force or the like. It is necessary to determine the assist direction (rotational direction) of the assist motor 8.

In order to determine the assist direction of the assist motor, for example, as disclosed in Japanese Patent Laid-Open No. 10-264842, the direction of rotation of the assist motor is determined by the detected current value of the assist motor and the terminal voltage of the motor. There is a method of estimating.

[0009]

In a device using a three-phase brushless motor as the assist motor,
When trying to estimate the rotation direction of the three-phase brushless motor (more precisely, the direction in which the torque is applied), there is a problem that the rotation direction cannot be estimated because the rotation direction changes depending on the circumferential position of the magnet rotor. It was

The present invention has been made in view of the above points, and an object thereof is to determine the driving direction of a brushless motor with a simple circuit structure and to operate the assist motor (three-phase) in the direction opposite to the steering assist direction. It is an object of the present invention to provide a brushless motor drive device capable of determining an abnormality of the device when a brushless motor) is driven (when reverse assist occurs).

[0011]

SUMMARY OF THE INVENTION A brushless motor driving device of the present invention for solving the above problems comprises a semiconductor control element connected in a multi-phase bridge between positive and negative output terminals of a DC power source,
In a brushless motor driving device configured by connecting a brushless motor between bridging points of the bridge circuit, a means for detecting the position of a magnet rotor of the brushless motor, wherein each phase winding of the stator coil is a magnet. Outputs either high level or low level signal when facing one pole of the rotor, and outputs either high level or low level when each phase winding of the stator coil faces the other pole of the magnet rotor. Position detection means for outputting the other one of the signals, and a signal corresponding to the drive signal of each phase of the semiconductor control element of the bridge circuit, of the semiconductor control element, for the ON-controlled phase It outputs either a high level signal or a low level signal, and a high level or low level signal is output for the phase controlled to be off. The energized phase signal output means for outputting the other one of the signals, the phase output signals of the position detection means and the phase output signals of the energized phase signal output means are logically ANDed with mutually different phases to obtain the logical A drive direction determining means for determining that the drive direction of the brushless motor is one direction when the product is established, and a drive direction determining means for determining that the drive direction of the brushless motor is the other direction when the logical product is not established. It is characterized by that.

Further, the driving direction discriminating means is characterized in that it has means for switching the phase of each phase output signal of either the position detecting means or the energized phase signal outputting means.

The brushless motor is an assist motor of an electric power steering device that applies a steering assist force corresponding to the detected torque of a torque sensor that detects a steering torque, and the brushless motor is discriminated by the drive direction discriminating means. Is provided with an abnormality determining means for determining an abnormality when the drive direction of No. 1 does not match the detected torque direction of the torque sensor.

[0014]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment in which the present invention is applied to the electric power steering apparatus of FIG. In FIG. 1, reference numeral 21 is a torque direction calculation unit that calculates the torque direction based on the detected torque of the torque sensor 7 that detects the steering torque of the steering wheel 1 described in FIG.

For example, when the polarity of the input detected torque signal is positive, the torque direction calculation unit 21 determines that it is in the right rotation direction (CW direction) and, for example, "1" in the binary signal. ”(High level signal) is output and the input signal polarity is negative, the counterclockwise rotation direction (CC
It is determined to be in the W direction), and "0" (low level signal) of the binary signals is output.

Reference numeral 22 denotes a position sensor (position detecting means) for detecting the position of the magnet rotor of the brushless motor (assist motor 8 in FIG. 5), and each phase winding of the stator coil has one pole (for example, one) of the magnet rotor. N
For example, "1" is output when facing the pole), and "0" is output when facing the other pole (S pole).

The position sensor 22 is composed of, for example, a Hall element, a photo interrupter, etc., and will be described later with reference to FIG.
As shown in (a), the sensor signals corresponding to each phase of W, V, and U are output, and these are introduced into one input end of the drive direction determination unit 23 having an AND circuit as 3-bit data. ing.

Reference numeral 24 denotes an upper FET drive signal output section (energized phase signal output means) that outputs a signal corresponding to a drive signal for each phase of a semiconductor control element shown in FIG. 4, which will be described later, as a drive circuit for the three-phase brushless motor. ). In particular,
Corresponding to a drive signal of, for example, an upper FET (of the positive electrode side arm) of a field effect transistor (hereinafter referred to as FET) connected in a three-phase bridge between positive and negative output terminals of a DC power source,
As shown in FIGS. 3B and 3C, which will be described later, for example, "1" is output for the on-controlled phase and "0" is output for the off-controlled phase.

Numeral 25 indicates the arrangement of the phase data of the output signal of the upper FET drive signal output section 24, which is indicated by the position sensor 2
It is a bit replacement unit that replaces the output data of the second output signal so as not to be the same as the array of the phase data. For example, the arrangement of the phase data of the output signal of the position sensor 22 is shown in FIG.
If it is “W, V, U” as shown in (a), the phase data of the output signal of the upper FET drive signal output unit 24 is shown in FIG.
As shown in (b) and (c), it is rearranged into "U, W, V".

The 3-bit data of the upper-stage FET drive signal thus rearranged is introduced into the other input terminal of the AND circuit of the drive-direction discriminating section 23, and the 3-bit data of the position sensor signal is obtained for each bit. Is ANDed with.

As a result, when any one of the phases (bits) becomes "1" as shown in FIG. 3B, the rotation direction of the three-phase brushless motor is one direction, for example, the right direction (CW direction). Then, the driving direction determination unit 23 outputs, for example, “1”, and when all the phases (bits) are all “0” as shown in FIG. 3C, the other direction, That is, the drive direction determination unit 23 determines that the direction is the left direction (CCW direction), and outputs “0”.

Whether or not the output signals of the torque direction calculation unit 21 and the drive direction determination unit 23 match in the matching circuit 26 (that is, whether or not the detected torque direction and the driving direction of the three-phase brushless motor match). ) Is determined. This matching circuit 26 is a logic circuit (matching circuit; Exclusi) that outputs “1” only when two inputs match, for example.
ve NOR).

That is, the outputs of the torque direction calculation unit 21 and the drive direction determination unit 23 are both in the right rotation direction (C
When the value is “1” indicating the W direction), the matching circuit 26 outputs “1”. When the outputs of the torque direction calculation unit 21 and the drive direction determination unit 23 are both “0” indicating the left rotation direction (CCW direction), the coincidence circuit 26.
Outputs "1". When the outputs of the torque direction calculation unit 21 and the drive direction determination unit 23 do not match, the matching circuit 26 outputs "0".

Reference numeral 27 is a negation circuit that inverts the output signal of the matching circuit 26, and 28 is an abnormality determination counter that adds the output signal of the negation circuit 27 and is cleared by the output signal of the matching circuit 26. . That is, the output of the coincidence circuit 26 is "0" (detected torque direction and 3
When the drive directions of the phase brushless motors do not match), and therefore the output of the NOT circuit 27 is "1", the count-up process is performed. Further, when the output of the matching circuit 26 is "1" (when the detected torque direction and the driving direction of the three-phase brushless motor match), the clear processing is performed.

An abnormality determination processing unit 29 determines whether or not the counter value of the abnormality determination counter 28 exceeds a specified value, and when it exceeds, sets an abnormality determination flag or the like. The coincidence circuit 26, the negation circuit 27, the abnormality determination counter 28, and the abnormality determination processing unit 29 constitute the abnormality determination means of the present invention. The abnormality determining means, the torque direction calculating unit 21, the driving direction determining unit 23,
The bit replacement unit 25 is, for example, the controller 11 of FIG.
It is provided inside.

After the abnormality determination flag is set, it is assumed that reverse assist has occurred, and safety processing such as stopping the driving of the three-phase brushless motor (assist motor) is executed.

Next, the operation of the apparatus configured as described above will be described with reference to the flowchart of the reverse assist determination processing of FIG. First, in step S ₁ , the torque sensor signal, the position sensor signal, and the upper FET drive signal are always fetched during operation.

Then, in step S ₂ , the steering torque direction is determined based on the torque sensor signal (by the torque calculation unit 21), the position sensor signal and the upper FET
The current direction of the three-phase brushless motor is determined based on the drive signal (bit replacement unit 25, drive direction determination unit 23
by).

Next, in step S ₃ , it is judged whether or not the steering torque direction and the current direction are different (by the coincidence circuit 26), and if they are different, step S ₄
At, the abnormality determination counter 28 counts up.

Next, in step S ₅ , it is determined whether or not the abnormality determination counter 28 has exceeded a specified value, and if it exceeds, the abnormality determination flag is set in step S ₆ (by the abnormality determination processing unit 29), This reverse assist determination process is repeated.

If the abnormality determination counter value does not exceed the specified value in step S ₅ , the reverse assist determination process is repeated, and it is determined in step S ₃ that the steering torque direction and the current direction are not different. In this case, after the abnormality determination counter 28 is cleared in step S ₇ , this reverse assist determination processing is repeated.

Next, a more specific operation of the drive direction discriminating section 23 will be described with reference to FIG. 3 showing the output signals of each section and FIG. 4 showing the relationship between the rotor position and the energizing direction of the three-phase brushless motor.

FIG. 3A shows the position sensor 22 of FIG.
The output signal of the position sensor 22 is
It is arranged in the center of the stator coils W, V, U shown in FIG. 4, and is "1" (high level signal) of the binary signal when facing the N pole of the magnet rotor, and "0" when facing the S pole. (Low level signal) is output. The arrow in the figure indicates the direction of rotation of the magnet rotor.

FIG. 3 (b) shows an output signal of the upper FET drive signal output section 24 when a current flows in one direction of the steering torque direction (CW direction), for example, the clockwise rotation direction,
The output (logical product output) result of the AND circuit of the drive direction determination unit 23 is shown.

FIG. 3 (c) shows the output signal of the upper FET drive signal output section 24 when the steering torque direction is the other direction (CCW direction), for example, when the current flows in the left rotation direction,
The output (logical product output) result of the AND circuit of the drive direction determination unit 23 is shown.

FIG. 4 shows, for each mode, the positional relationship between the energized phase and the magnet rotor when torque is output in one direction (CW direction), for example, clockwise rotation.
V and U represent windings of each phase of the stator coil, diode symbols shown in the figure represent FETs that are off-controlled among bridge-connected FETs, and resistance symbols shown in the figure represent FETs that are on-controlled.

FIG. 4A shows a mode in which a current is passed between the W and U phases, and the magnet rotor is assumed to be in the position shown in the figure. In this case, the upper FET WH of the W phase and the lower F of the U phase
Only ETUL is turned on, and the current flows through FETWH → stator coil W → stator coil U → FETUL.

Therefore, the W phase becomes an N pole and a force attracting the S pole of the magnet rotor is generated, and the U phase becomes an S pole and a force repulsive to the S pole of the magnet rotor is generated. Therefore, the magnet rotor rotates in one direction (CW direction), for example, rightward.

At this time, the output of the position sensor 22 is, as shown in FIG. 3A, the W phase, that is, SEN _W is "0" (because it faces the S pole of the rotor), the V phase, that is, SEN _V. Is "1" (because it faces the N pole of the rotor), U phase, that is, SEN _U is "0" (S of rotor is
Because it is facing the pole).

Since only the W phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (b), W phase, that is, WH is "1", V
The phase, that is, VH is “0”, and the U phase, that is, UH is “0”.

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, "010".
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product with H, that is, "010" is "010".

FIG. 4B shows a mode in which an electric current is passed between the V and U phases, and the magnet rotor has a 6th mode as compared with FIG. 4A.
It is in the position shown in the figure rotated right by 0 °. in this case,
Only the upper FET VH of the V phase and the lower FET UL of the U phase are on-controlled, and the current flows through FETVH → stator coil V → stator coil U → FETUL.

Therefore, the V-phase becomes an N pole and a force repulsive to the N-pole of the magnet rotor is generated, and the U-phase becomes an S pole and a force attracting the N-pole of the magnet rotor is generated. Therefore, the magnet rotor rotates in one direction (CW direction), that is, to the right.

At this time, as shown in FIG. 3A, the output of the position sensor 22 has SEN _W of "0" (S of the rotor is S
SEN _V is “1” (because it faces the N pole of the rotor) and SEN _U is “1” (because it is opposite the N pole of the rotor).

Since only the V phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (b), WH is “0”, VH is “1”, U
H becomes "0".

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, “011”.
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product of H, that is, "001" is "001".

FIG. 4C shows a mode in which an electric current is passed between the V and W phases, and the magnet rotor is 6 more than in FIG. 4B.
It is in the position shown in the figure rotated right by 0 °. in this case,
Only the upper FET VH of the V phase and the lower FET WL of the W phase are on-controlled, and the current flows through the FET VH → stator coil V → stator coil W → FETWL.

Therefore, the V phase becomes an N pole and a force attracting the S pole of the magnet rotor is generated, and the W phase becomes an S pole and a force repulsive to the S pole of the magnet rotor is generated. Therefore, the magnet rotor rotates in one direction (CW direction), that is, to the right.

At this time, as shown in FIG. 3 (a), the output of the position sensor 22 has SEN _W of "0" (S of the rotor S
SEN _V becomes “0” (because it faces the S pole of the rotor) and SEN _U becomes “1” (because it faces the N pole of the rotor).

Since only the V phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (b), WH is “0”, VH is “1”, U
H becomes "0".

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, "001".
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product of H, that is, "001" is "001".

FIG. 4 (d) shows a mode in which a current is passed between the U and W phases, and the magnet rotor has a greater number than that in FIG. 4 (c).
It is in the position shown in the figure rotated right by 0 °. in this case,
Only the upper FET UH of the U phase and the lower FET WL of the W phase are on-controlled, and the current flows through FET UH → stator coil U → stator coil W → FET WL.

Therefore, the U-phase becomes an N pole and a repulsive force with the N-pole of the magnet rotor is generated, and the W-phase becomes an S pole and a force attracting the N-pole of the magnet rotor is generated. Therefore, the magnet rotor rotates in one direction (CW direction), that is, to the right.

At this time, as shown in FIG. 3 (a), the output of the position sensor 22 is SEN _W "1" (rotor N
SEN _V becomes “0” (because it faces the S pole of the rotor) and SEN _U becomes “1” (because it faces the N pole of the rotor).

Since only the U-phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (b), WH is “0”, VH is “0”, U
H becomes "1".

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, “101”.
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product with H, that is, “100” is “100”.

FIG. 4 (e) shows a mode in which a current is passed between the U and V phases, and the magnet rotor has more than 6 magnets as shown in FIG. 4 (d).
It is in the position shown in the figure rotated right by 0 °. in this case,
Only the upper FET UH of the U phase and the lower FET VL of the V phase are on-controlled, and the current flows through FET UH → stator coil U → stator coil V → FET VL.

Therefore, the U-phase becomes an N-pole and a force attracting the S-pole of the magnet rotor is generated, and the V-phase becomes an S-pole and a force repulsive to the S-pole of the magnet rotor is generated. Therefore, the magnet rotor rotates in one direction (CW direction), that is, to the right.

At this time, as shown in FIG. 3A, the output of the position sensor 22 has SEN _W of "1" (rotor N
SEN _V is “0” (because it faces the S pole of the rotor), and SEN _U is “0” (because it is opposite the S pole of the rotor).

Since only the U-phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (b), WH is “0”, VH is “0”, U
H becomes "1".

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, "100".
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product with H, that is, “100” is “100”.

FIG. 4 (f) shows a mode in which an electric current is passed between the W and V phases, and the magnet rotor has more than 6 magnets as shown in FIG. 4 (e).
It is in the position shown in the figure rotated right by 0 °. in this case,
Only the upper FET WH of the W phase and the lower FET VL of the V phase are on-controlled, and the current flows through FETWH → stator coil W → stator coil V → FETVL.

Therefore, the W phase becomes an N pole and a repulsive force with the N pole of the magnet rotor is generated, and the V phase becomes an S pole and a force attracting the N pole of the magnet rotor is generated. Therefore, the magnet rotor rotates in one direction (CW direction), that is, to the right.

At this time, as shown in FIG. 3A, the output of the position sensor 22 is SEN _W "1" (rotor N
SEN _V is “1” (because it faces the N pole of the rotor) and SEN _U is “0” (because it is opposite the S pole of the rotor).

Since only the W phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (b), WH is “1”, VH is “0”, U
H becomes "0".

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, “110”.
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product with H, that is, "010" is "010".

As shown in FIGS. 4 (a) to 4 (f), when the rotation direction is one direction (CW), for example, right rotation, the AND result of the drive direction discriminating unit 23 is shown in FIG. 3 (b). As shown, the logical product is established in any of the bits (any phase is “1”).

Next, the rotation direction is the other direction (CCW direction),
That is, let us examine the case of left-handed rotation. The torque can be output in the CCW direction by reversing the energization direction when outputting the torque in the CW direction. That is, the directions of the currents flowing in the FET and the stator coil connected in the bridge shown in FIG. 4 are opposite (that is, the upper FET and the lower FET are opposite).

For example, it is assumed that the magnet rotor is in the position shown in FIG. 4 (f) in the mode in which the current is applied between the V and W phases. In this case, V-phase upper FET and W-phase lower F
Only ET is turned on, and the current flows through the V-phase upper stage FET → stator coil V → stator coil W → lower stage FET.

Therefore, the V-phase becomes an N pole and a force repulsive to the N-pole of the magnet rotor is generated, and the W-phase becomes an S pole and a force attracting the N-pole of the magnet rotor is generated. Therefore, the magnet rotor moves in the other direction (CCW direction),
That is, it rotates to the left.

At this time, as shown in FIG. 3 (a), the output of the position sensor 22 is SEN _W "1" (rotor N
SEN _V is “1” (because it faces the N pole of the rotor) and SEN _U is “0” (because it is opposite the S pole of the rotor).

Since only the V phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (c), WH is “0”, VH is “1”, U
H becomes "0".

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, “110”.
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product of H, that is, "001" is "000".

Next, in the mode in which a current is applied between the V and U phases, the magnet rotor is at the position shown in FIG. 4 (e), which is rotated 60 ° to the left from the position shown in FIG. 4 (f). In this case, only the V-phase upper FET and the U-phase lower FET are turned on, and the current is V-phase upper FET → stator coil V →
The stator coil U → flows through the U-phase lower FET.

Therefore, the V-phase becomes an N pole and a force attracting the S-pole of the magnet rotor is generated, and the U-phase becomes an S pole and a force repulsive to the S-pole of the magnet rotor is generated. Therefore, the magnet rotor moves in the other direction (CCW direction),
That is, it rotates to the left.

At this time, as shown in FIG. 3A, the output of the position sensor 22 is SEN _W "1" (rotor N
SEN _V is “0” (because it faces the S pole of the rotor), and SEN _U is “0” (because it is opposite the S pole of the rotor).

Since only the V phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (c), WH is “0”, VH is “1”, U
H becomes "0".

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, "100".
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product of H, that is, "001" is "000".

Next, in the mode in which a current is passed between the W and U phases, the magnet rotor is at the position shown in FIG. 4 (d), which is rotated 60 ° to the left from that in FIG. 4 (e). In this case, only the upper FET of the W phase and the lower FET of the U phase are on-controlled, and the current is the upper FET of the W phase → stator coil W →
The stator coil U → flows through the U-phase lower FET.

Therefore, the W phase becomes an N pole and a force repulsive to the N pole of the magnet rotor is generated, and the U phase becomes an S pole and a force attracting the N pole of the magnet rotor is generated. Therefore, the magnet rotor moves in the other direction (CCW direction),
That is, it rotates to the left.

At this time, as shown in FIG. 3 (a), the output of the position sensor 22 has SEN _W of "1" (rotor N
SEN _V becomes “0” (because it faces the S pole of the rotor) and SEN _U becomes “1” (because it faces the N pole of the rotor).

Since only the W phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (c), WH is “1”, VH is “0”, U
H becomes "0".

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, “101”.
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product with H, that is, "010" is "000".

Next, in the mode in which a current is passed between the W and V phases, the magnet rotor is at the position shown in FIG. 4 (c), which is rotated 60 ° to the left from that in FIG. 4 (d). In this case, only the W-phase upper FET and the V-phase lower FET are on-controlled, and the current is W-phase upper FET → stator coil W →
It flows through the lower FET of the stator coil V → V phase.

Therefore, the W phase becomes an N pole and a force attracting the S pole of the magnet rotor is generated, and the V phase becomes an S pole and a force repulsive to the S pole of the magnet rotor is generated. Therefore, the magnet rotor moves in the other direction (CCW direction),
That is, it rotates to the left.

At this time, as shown in FIG. 3A, the output of the position sensor 22 has SEN _W of "0" (S of the rotor is S
SEN _V becomes “0” (because it faces the S pole of the rotor) and SEN _U becomes “1” (because it faces the N pole of the rotor).

Since only the W phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (c), WH is “1”, VH is “0”, U
H becomes "0".

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, “001”.
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product with H, that is, "010" is "000".

Next, in the mode in which a current is passed between the U and V phases, the magnet rotor is at the position shown in FIG. 4 (b) which is rotated 60 ° to the left from that in FIG. 4 (c). In this case, only the upper FET of the U phase and the lower FET of the V phase are on-controlled, and the current is the upper FET of the U phase → stator coil U →
It flows through the lower FET of the stator coil V → V phase.

Therefore, the U phase becomes an N pole and a force repulsive to the N pole of the magnet rotor is generated, and the V phase becomes an S pole and a force attracting the N pole of the magnet rotor is generated. Therefore, the magnet rotor moves in the other direction (CCW direction),
That is, it rotates to the left.

At this time, as shown in FIG. 3 (a), the output of the position sensor 22 is SEN _W "0" (S
SEN _V is “1” (because it faces the N pole of the rotor) and SEN _U is “1” (because it is opposite the N pole of the rotor).

Since only the U-phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (c), WH is “0”, VH is “0”, U
H becomes "1".

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, “011”.
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product with H, that is, "100" is "000".

Next, in the mode in which a current is passed between the U and W phases, the magnet rotor is at the position shown in FIG. 4A, which is rotated 60 ° to the left from the position shown in FIG. 4B. In this case, only the upper FET of the U phase and the lower FET of the W phase are turned on, and the current is the upper FET of the U phase → stator coil U →
The stator coil W → flows through the W-phase lower FET.

Therefore, the U-phase becomes an N-pole and a force attracting the S-pole of the magnet rotor is generated, and the W-phase becomes an S-pole and a force repulsive to the S-pole of the magnet rotor is generated. Therefore, the magnet rotor moves in the other direction (CCW direction),
For example, it rotates to the left.

At this time, as shown in FIG. 3A, the output of the position sensor 22 has SEN _W of "0" (S of the rotor is S
SEN _V is “1” (because it faces the N pole of the rotor) and SEN _U is “0” (because it is opposite the S pole of the rotor).

Since only the U phase of the upper FET is on, the output of the upper FET drive signal output section 24 is as shown in FIG.
As shown in (c), WH is “0”, VH is “0”, U
H becomes "1".

Therefore, the output data SEN _W , SEN _V , SEN _{U of} the position sensor 22, that is, “010”.
And data UH, WH, V obtained by rearranging the output data of the upper FET drive signal output unit 24 by the bit rearrangement unit 25.
The logical product with H, that is, "100" is "000".

As described above, the rotation direction is the other direction (C
CW), for example, in the case of counterclockwise rotation, the AND result of the drive direction determination unit 23 is not logically established for all the bits as shown in FIG. 3C (all phases are “0”). Will be).

Therefore, the drive direction discriminating section 23 can accurately discriminate the drive direction of the three-phase brushless motor. Further, since the abnormality determination process is performed by the output of the matching circuit 26, the reverse assist can be prevented even in the electric power steering device using the three-phase brushless motor.

The bit replacing section 25 replaces the bits of the output data of the upper FET drive signal output section 24 so as not to be the same as the arrangement of the phase data of the output signal of the position sensor 22, and the above-mentioned "W, V,
It is not limited to switching from "U" to "U, W, V".
You may replace "V, U" with "V, U, W".

The bit replacement section 25 is an upper FET.
The drive signal output unit 24 is not limited to be provided in the subsequent stage, but may be provided in the subsequent stage of the position sensor 22 and the bit of the position sensor signal may be exchanged.

Further, the position sensor 22 outputs a high level signal, for example, "1" when each phase winding of the stator coil faces one pole of the magnet rotor, but the position sensor 22 is not limited to this. Level signal, eg "0"
May be configured to be output.

Further, the energization phase signal output means of the present invention is not limited to the provision of the upper FET drive signal output section 24, but outputs a signal corresponding to the drive signal of the lower FET of the bridge-connected FETs. It may be configured to.

Further, the abnormality determining means of the present invention is not limited to the configuration of FIG. 1 and may be configured by other circuits.

Further, the semiconductor control element to be bridge-connected is not limited to the FET, and other semiconductor elements such as a transistor, a thyristor and a gate turn-off thyristor may be used.

The present invention is not limited to being applied to the electric power steering device, but may be applied to other devices using a brushless motor.

The present invention is not limited to being applied to a three-phase brushless motor, but can be applied to a four-phase or more brushless motor.

[0109]

As described above, according to the present invention, the driving direction of the brushless motor can be easily determined with a simple circuit configuration. Further, since the abnormality determining means is provided, it is possible to reliably prevent reverse assist in the electric power steering device.

[Brief description of drawings]

FIG. 1 is a block diagram showing an exemplary embodiment of the present invention.

FIG. 2 is a flow chart of reverse assist determination processing, which represents an embodiment of the present invention.

3A and 3B show an example of an embodiment of the present invention, FIG. 3A is a waveform diagram showing an output signal of a position sensor, and FIG. 3B is a signal of an upper FET drive signal output section in a torque direction CW (one direction). Waveform diagram, (c) torque direction CCW (other direction)
The signal waveform diagram of the upper stage FET drive signal output part at the time.

FIG. 4 illustrates an exemplary embodiment of the present invention, in which (a) is W-U.
Operation explanatory drawing when flowing current between phases, (b) operation explanatory drawing when flowing current between V-U phases, (c) operation explanatory drawing when flowing current between V-W phases, (d) Is an operation explanatory diagram when a current is passed between the U and W phases, (e) is an operation explanatory diagram when a current is passed between the U and V phases, and (f) is an operation explanatory diagram when a current is passed between the W and V phases .

FIG. 5 is a configuration diagram showing an example of an electric power steering device.

[Explanation of symbols]

1 ... Steering wheel 7 ... Torque sensor 8 ... Assist motor 12 ... Relay circuit 13 ... Battery 21 ... Torque direction calculation unit 22 ... Position sensor 23 ... Driving direction determination unit 24 ... Upper FET drive signal output section 25 ... Bit replacement section 26 ... Matching circuit 27 ... Negation circuit 28 ... Abnormality judgment counter 29 ... Abnormality determination processing unit

Claims (3)

[Claims] 1. A brushless motor drive apparatus comprising a semiconductor control element connected in a multi-phase bridge between positive and negative output terminals of a DC power source, and a brushless motor connected between bridge points of the bridge circuit. A means for detecting the position of a magnet rotor of a motor, which outputs one of a high level signal and a low level signal when each phase winding of the stator coil faces one pole of the magnet rotor. Position detecting means for outputting either the high level signal or the low level signal when each phase winding faces the other pole of the magnet rotor, and the drive signal for each phase of the semiconductor control element of the bridge circuit. Corresponding signal, which is either high level or low level for the ON-controlled phase of the semiconductor control element One of the energized phase signal output means that outputs one of the signals and outputs either the high level signal or the low level signal for the phase controlled to be off, each phase output signal of the position detection means and the energized state. The phase output signals of the phase signal output means are logically ANDed between mutually different phases, and when the logical AND is established, it is determined that the driving direction of the brushless motor is one direction, and the logical AND is not established. At this time, the brushless motor driving device is provided with a driving direction judging means for judging that the driving direction of the brushless motor is the other direction. 2. The drive direction determination means includes means for switching the phase of each phase output signal of either the position detection means or the energized phase signal output means. 1. The drive device for the brushless motor according to 1. 3. The brushless motor comprises an assist motor of an electric power steering device for applying a steering assist force according to a detected torque of a torque sensor for detecting a steering torque, and the brushless discriminated by the driving direction discriminating means. The brushless motor drive device according to claim 1 or 2, further comprising an abnormality determination unit that determines an abnormality when a drive direction of the motor does not match a detected torque direction of the torque sensor.