JPH05184184A - Motor driving circuit - Google Patents

Abstract

PURPOSE:To get driving waveform geared to the revolution of a motor even if it changes, by correcting the phase difference between the rotational position of the motor and the waveform data by the delay time from the detection of position and the output of wave data, in a motor driving circuit which has a waveform memory for driving a motor. CONSTITUTION:A free counter 22, which counts the output signal SFG of FG3 independently, is provided in addition to a counter 5, which counts the positional relation between the rotor and the stator of a motor 2 by the output signal SFG of GF3 and the output signal SPC of a positional detector 7. This free counter 22 receives clock signals CLK from a clock generating circuit 21, and sends out a detection signal SDET, which shows the cycle of the output signal SFG of FG3, to CPU6. CPU6 calculates the correction geared to the cycle of the output signal SFG in real time, and adds it to the reference waveform data read out of a waveform memory 8, and drives the motor 2 by the waveform data geared o the rotational position.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Industrial Application Conventional Technology (FIG. 4) Problem to be Solved by the Invention (FIGS. 5 and 6) Means for Solving the Problem (FIG. 1) Action (FIG. 1) Example (FIGS. 1 to 3) ) The invention's effect

[0002]

BACKGROUND OF THE INVENTION The present invention relates to a motor drive circuit,
It is particularly suitable for application to a motor drive circuit having a waveform memory for driving a motor.

[0003]

2. Description of the Related Art Conventionally, in a motor drive circuit, a drive current waveform is stored in a predetermined waveform memory in advance, and the waveform data is output at a predetermined timing based on a position detection signal from the motor. There is a device in which the motor is driven by the waveform data while being synchronized with the rotation of the motor.

That is, as shown in FIG. 4, the motor drive circuit 1 has a frequency corresponding to the number of rotations of the motor 2 from an FG (frequency generator) 3 provided in the motor 2 as the motor 2 rotates. The FG output signal S _FG is output and sent to the counter 5.

Further, the motor 2 is provided with a position detecting device 7 composed of, for example, a PG (pulse generator) in order to detect a reference position during one rotation, and an output signal S _PG from the position detecting device 7 is countered. 5 is input as a reset signal.

The counter 5 is reset by the output signal S _PG from the position detecting device 7, and subsequently by the FG output signal S _FG input at a predetermined interval (interval corresponding to the rotation speed of the motor 2). Then, the counting operation is performed.

The count value represents the positional relationship between the rotor and the stator of the motor 2, and the CPU 6 determines the positional relationship between the rotor and the stator from the waveform memory 8 having a ROM (read only memory) structure based on the counted value. The waveform data DATA1 of the different address are controlled to be output.

Here, the waveform data for driving the motor stored in the waveform memory 8 has the following equation, where N _{FG is} the number of teeth of _FG and P is the number of magnet poles.

[Equation 1] It is divided by the number of divisions N represented by, and is stored at addresses corresponding to the positional relationship between the rotor and the stator of the motor 2, respectively.

Accordingly, the read waveform data DAT
A1 is converted into an analog signal in the subsequent digital-analog conversion circuit (D / A) 9 to obtain a drive waveform SIG1 and then sent to the coil 11 of the motor 2 via the amplifier circuit 10 so that the rotor of the motor 2 and The motor 2 is driven by the waveform data DATA1 according to the positional relationship of the stator.

[0010]

However, in the motor drive circuit 1 of this type, the FG output signal S from the motor 2 is generated.
_{After FG} is output, the corresponding waveform data DATA1
It is unavoidable that a predetermined time is required as software processing time to read out and output to the coil 11 of the motor 2, and if the drive waveform is output with a delay by the required time, the rotor rotates at the output speed. Therefore, it is difficult to drive the motor 2 with an optimum drive waveform according to the rotor position of the motor 2.

That is, as shown in FIG. 5, the falling edge (time points t1 and t) of the FG output signal S _FG (FIG. 5A).
At 3, t5, ...), an FG interrupt signal is generated,
As a result, when the counter 5 is operated to count, the F
Waveform data DA from the falling edge of the G output signal S _FG
A delay time T _DT (FIG. 5B) from when TA1 is read and output to the coil 11 is generated.

Accordingly, the drive waveform SIG1 is actually the coil 1
1 is output at time t2, t at which the delay time T _DT has elapsed from the falling edge of the FG output signal S _FG.
4, t6, ...

Here, assuming that the drive waveform SIG1A shown by the solid line in FIG. 5C is an ideal drive waveform with no delay time, the waveform data DATA1A for obtaining the drive waveform SIG1A is the falling edge of the FG output signal S _FG . At edges (time points t1, t3, t5, ...), data U (0), U (1), U (2) ,.

Actually, however, the above-mentioned delay time T _DT is generated, so that the delay time T _DT has elapsed as shown by the waveform data DATA1B indicated by the broken line in FIG. 5C.
Similar data U at 2, t4, t6, ...
(0), U (1), U (2), ...
Drive waveform SIG1 based on the waveform data DATA1B
B has a waveform whose phase is delayed by the delay time T _DT as a whole.

As a result, the motor 2 cannot obtain the drive waveform corresponding to the rotor position, which causes the efficiency of the motor 2 to decrease, the torque ripple to deteriorate, and the acoustic noise due to the unnecessary current to increase. Will result.

As a method for solving this problem, a method of storing the waveform data corrected by the delay time in the waveform memory 8 in advance is considered. That is, the waveform data DATA indicated by the alternate long and short dash line in FIG.
1C is at times t1, t3 when the FG output signal S _FG falls,
When the delay time elapses from t5, ... T2, t
At 4, t6, ..., Data U (0) ', U (1)', U (2) ', ... Corrected by the delay time are raised, and obtained based on the waveform data DATA1C. The drive waveform SIG1C has the same phase as the ideal drive waveform SIG1A with no delay time.

Therefore, according to this method, when the motor 2 is rotating at a constant number of rotations, it is possible to obtain a drive waveform corresponding to the rotor position of the motor 2. However, in this method, it is assumed that the motor 2 is rotating at a predetermined rotation speed as the waveform data stored in advance in the waveform memory 8, and it is premised that the rotation speed of the motor 2 is constant. ..

Therefore, when the motor 2 rotates at a higher speed than that shown in FIG. 5, the waveform data DATA1C (U (0) ', U (1)', U corrected to match the low speed rotation is used.
Even if (2) ′, ...) Is used, the correction amount is insufficient, and as shown in FIG. 6 in which the same parts as those in FIG. 5 are denoted by the same reference numerals, the waveform data DATA1C (U (0) ′, U (1) ', U
(2) ′, ... Drive waveform SIG1C (FIG. 6)
Even if (C)) is used, it does not equal the ideal drive waveform SIG1A, and there is a problem that the motor 2 cannot obtain a drive waveform according to the rotor position.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose a motor drive circuit which can obtain a drive waveform corresponding to the change in the rotation speed of the motor. ..

[0020]

In order to solve such a problem, the present invention has a storage means 8 for storing waveform data DATA2 representing the drive waveform SIG2 of the motor 2,
In the motor drive circuit 20 that outputs waveform data DATA2 corresponding to the rotational position of the motor 2 based on the position detection signal S _PG from the motor 2 to the coil 11 of the motor 2, the position detection signal S _PG from the motor 2 is output The rotational position of the motor 2 and the phase difference between the waveform data DATA2 due to the delay time T _DT until the post-waveform data DATA2 is output to the motor 2 are corrected based on the information T _FG representing the rotational speed of the motor 2.

[0021]

Operation: After the rotational position detection signal S _PG is output from the motor 2, the motor 2 at the delay time T _DT until the waveform data DATA2 corresponding to the rotational position is output to the motor 2
Waveform data DA of the waveform memory 8 according to the rotation advance amount of
By correcting and outputting TA2, the motor 2 can be driven by the waveform data DATA2C according to the rotational position of the motor 2.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, in which parts corresponding to those in FIG. 4 are designated by the same reference numerals, the motor drive circuit 20 includes a counter 5 that counts the FG output signal S _FG output from the FG 3 and operates independently. A run counter 22 is provided.

The free-run counter 22 inputs a clock signal CLK having a frequency sufficiently higher than the frequency of the FG output signal S _FG from the clock generation circuit 21, and outputs the clock signal CLK with a pulse of the FG output signal S _FG . By counting while gated, the FG output signal S _FG
Is to measure the cycle of.

The detection signal S _DET indicating the cycle of the FG output signal S _FG detected by the free-run counter 22 is sent to the subsequent CPU 6, and the CPU 6 calculates the correction amount according to the cycle of the FG output signal S _FG in real time. To do.

The correction amount calculated here is added to the reference waveform data read from the subsequent waveform memory 8, and the waveform data DATA2 corrected by the correction amount is sent to the digital-analog conversion circuit 9.

The reference waveform data stored in the waveform memory 8 is the waveform data DATA2B which is not corrected by the delay time T _DT as shown in FIG.
Waveform data DATA1B (U (0),
The same as U (1), U (2), ...).

Therefore, the correction amount Δ according to the rotation speed of the motor 2
The reference waveform data DATA2B (U (0), U
By correcting (1), U (2), ...), the waveform data DATA2C (U
(0) ″, U (1) ″, U (2) ″, ...) Are obtained.

As a method of calculating the correction amount Δ, two continuous waveform data are linearly approximated and the data between them is F
A method of interpolating according to the cycle of the G output signal S _FG is used. Therefore, the reference waveform data corresponding to the rotor position of the motor 2 is U (n), and the next reference waveform data is U (n +).
1), cycle of FG output signal S _FG is T _FG , delay time is T _DT
Then, the corrected waveform data U (n) ″ is calculated by the following equation.

[Equation 2] It is calculated by

In the equation (2), since the delay time T _DT is constant in the motor drive circuit 20,
When the period T _FG of the FG output signal S _FG becomes shorter (that is, the rotational speed of the motor 2 becomes faster)) correction amount Δ becomes large, and if the period T _FG of the FG output signal S _FG becomes longer (i.e. rotation of the motor 2 The correction amount Δ decreases as the speed decreases.

As a result, even if the rotation speed of the motor 2 changes, the reference waveform data DATA2 is corrected with a correction amount according to the change.
B (U (0), U (1), U (2), ...) Can be corrected, and for example, even when the rotation speed of the motor 2 is high as shown in FIG. The obtained waveform data DATA2C can be obtained.

Thus, by converting the waveform data DATA2C into an analog signal in the digital-analog conversion circuit 9, the drive waveform SIG2C having the same phase as the ideal drive waveform SIG2A corresponding to the rotor position of the motor 2 is obtained.
Can be obtained.

In the above configuration, the motor drive circuit 20
, The delay time T _DT is constant, while the motor 2 is driven at various rotation speeds. Therefore, the amount by which the rotor of the motor 2 advances with a constant delay time T _DT varies depending on the rotation speed of the motor 2.

The amount of advance of the rotor is obtained from the cycle of the FG output signal S _FG , and the waveform data DATA corresponding to the amount of advance is obtained.
By calculating 2C by the above equation (2), the motor 2 is driven by the drive waveform SIG2C having a phase corresponding to the actual rotor position.

According to the above configuration, since the phase difference between the rotor position and the drive waveform can be eliminated, the efficiency of the motor 2 is reduced due to the phase difference, the torque ripple is deteriorated, and the acoustic noise due to the unnecessary current is increased. The harmful effect can be effectively avoided.

In the above-mentioned embodiment, the case where the equation (2) is used as the method for calculating the waveform data U (n) ″ has been described, but the present invention is not limited to this and various calculation methods are used. be able to.

In the above embodiment, the case where the PG is used as the position detecting device 7 has been described, but the present invention is not limited to this, and the point is that the absolute rotational position of the motor can be detected. ..

Further, in the above embodiment, the case where the ROM is used as the waveform memory 8 has been described, but the present invention is not limited to this, and various other storage means can be used.

Further, in the above-described embodiment, the case where the free-run counter 22 is used is described as the method for measuring the cycle of the FG output signal S _FG , but the present invention is not limited to this, and the rotation speed of the motor 2 is not limited to this. It is possible to apply various methods such as obtaining from.

[0040]

As described above, according to the present invention, the rotation advance amount of the motor in the delay time after the rotation position detection signal is output from the motor until the waveform data corresponding to the rotation position is output to the motor. By correcting the waveform data in the waveform memory and outputting the corrected waveform data, it is possible to realize a motor drive circuit capable of driving the motor with a drive waveform corresponding to the rotational position of the motor.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a motor drive circuit according to the present invention.

FIG. 2 is a signal waveform diagram showing waveform data during low speed rotation according to an embodiment.

FIG. 3 is a signal waveform diagram showing waveform data during high-speed rotation according to an example.

FIG. 4 is a block diagram showing a conventional motor drive circuit.

FIG. 5 is a signal waveform diagram showing waveform data during low speed rotation according to a conventional example.

FIG. 6 is a signal waveform diagram showing waveform data during high speed rotation according to a conventional example.

[Explanation of symbols]

1, 20 ... Motor drive circuit, 2 ... Motor, 3 ... F
G, 5 ... Counter, 6 ... CPU (Central Processing Unit),
8 ... Waveform memory (ROM), 11 ... Coil, 21 ...
… Clock generation circuit, 22 …… Free-run counter.

Claims (1)

[Claims] 1. A storage means for storing waveform data representing a drive waveform of a motor, wherein the waveform data corresponding to a rotational position of the motor is output to a coil of the motor based on a position detection signal from the motor. In the motor drive circuit, the rotational position of the motor and the phase difference between the waveform data depending on the delay time until the waveform data is output to the motor after the position detection signal is output from the motor A motor drive circuit characterized in that the correction is performed based on information indicating