JPH1118478A - Controller and control method for dc brushless motor drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the effect of noise in a positional signal being fed to a microcomputer by canceling a signal which is applied to the positional signal input port, if a trailing edge or a leading edge caused by a noise is inputted thereto. SOLUTION: Every time when the trailing edge tel1, tel2, tel3 or a leading edge le1, le2, le3 of a signal is inputted to the input port for positional signal Sint of a microcomputer, the level of each pulse in the positional signal Sint, i.e., the high/lows state α1, α2, αd1, α3, α4, α5, αd2, is detected. A decision is then made whether or not it is inverted normally with respect to the high/low state of a positional signal pulse detected previously. When a decision has been made that a noise signal is inputted, the signal related to that trailing edge or leading edge is canceled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless DC motor drive control method and apparatus, and more particularly, to a method for controlling a rotor and a stator based on an induced voltage induced in an armature coil of a brushless DC motor. The present invention relates to a brushless DC motor drive control method and apparatus for detecting a position signal representing a relative position of the armature coil and controlling a voltage pattern of an armature coil based on the position signal.

[0002]

2. Description of the Related Art Brushless DC motors are generally diversified in various fields because they can improve the use restriction, maintainability and environmental resistance due to commutation sparks caused by mechanical commutators of general DC motors. 8, reference numeral 50 denotes a rotor having a plurality of permanent magnets in a brushless DC motor, and reference numeral 51 denotes a three-phase Y-connected armature coil 51a.
A stator having 51b and 51c is shown, respectively.

[0003] A conventional brushless DC motor drive control device for driving such a brushless DC motor is shown in FIG.
First, the rotational position detector 53 detects the relative rotational position of the rotor 50 with respect to the armature coils 51a, 51b, 51c. Then, a position signal Sint representing the rotational position of the rotor 50 is given from the rotational position detector 53 to a microcomputer (hereinafter abbreviated as “microcomputer”) 54, and based on the position signal Sint, the microcomputer 54 sends a signal to the drive circuit 55. A predetermined switching signal is provided.
As a result, based on the commutation control signal output from drive circuit 55, armature coil 5
The voltage patterns of 1a, 51b and 51c are switched.

Here, the inverter unit 60 is connected to the DC power supply 5.
Three transistors 6 respectively connected to the positive electrode side of the transistor 6
0a, 60b, 60c and three transistors 60d, 60e, 6 connected to the negative side of the DC power source 56, respectively.
0f. The emitter of transistor 60a and the collector of transistor 60d are connected to each other, the emitter of transistor 60b and the collector of transistor 60e are connected to each other, and the emitter of transistor 60c and the collector of transistor 60f are connected to each other. Transistors 60a, 60
A U-phase armature coil 51a is connected to a connection midpoint between the ds, a V-phase armature coil 51b is connected to a connection midpoint between the transistors 60b and 60e, and a connection midpoint between the transistors 60c and 60f. Is connected to a W-phase armature coil 51c. And the drive circuit 5
5 is applied to each of the transistors 60a to 60f.
Is entered into each of the bases. Each of these transistors 60a to 60f is an insulated gate transistor (IGB
T) elements are used.

In the rotational position detector 53, first, three resistors 61a, 61b, and 61c of a resistor circuit 61 are connected in a three-phase connection in parallel with the armature coils 51a, 51b, and 51c. the voltage V _M at the neutral point of the resistor circuit 61, the armature coils 51a, 51b, the potential difference signal V _MN the integrating amplifier circuit 62 that indicates the potential difference between the voltage V _N at the neutral point of 51c (ground potential in this case) Integrate with The integrated signal Int from the integrating amplifier circuit 62 is shaped by the zero cross comparator 63 and then the photocoupler 64
And the square wave signal output from the photocoupler 64 is applied to the armature coils 51a, 51a of the stator 51.
The position signal Sint indicating the relative position of the rotor 50 with respect to b and 51c is output to the microcomputer 54.

Further, the microcomputer 54 sets one high state and one low state as one pulse unit for the square wave position signal Sint given from the rotational position detector 53 through the interrupt terminal 70. The pulse width T of the high state or the low state for each pulse unit (FIG. 10)
Measuring unit 71, a target Tx input unit 73 for receiving a target pulse width Tx (FIG. 10) provided from an external input means 72 such as an operation panel into the microcomputer 54, and a pulse detected by the T measuring unit 71. A speed calculator 74 for calculating a desired rotation speed according to the difference between the width T and the target pulse width Tx received at the target Tx input unit 73, and a desired inverter voltage V according to the calculation result of the speed calculator 74 An inverter voltage V determining unit 75, a PWM modulator 76 that modulates and generates an appropriate PWM pulse wave based on a desired rotation speed and the inverter voltage V, and outputs an appropriate switching signal to the drive circuit 55 based on the PWM pulse wave. And an inverter waveform signal output unit 77.

In this brushless DC motor drive control device, the U-phase, V-phase, and W-phase motor terminal voltages from the inverter section 60 are V _U , V _V , and V _W , respectively, and the armature coils 51a, 51b, and 51c are provided. each U-phase, V-phase, respectively E _U induced voltage of the W-phase, E _V, when the E _W, the voltage V _M at the neutral point of the resistor circuit 61 and the armature coils 51a, 51
b, the voltage V _N at the neutral point of 51c, _{respectively, V M = (1/3) (} V U + V V + V W) V N = (1/3) {(V U -E U) + ( V _V −E _V ) + (V _W
−E _W )｝. Accordingly, the neutral point and the armature coil 51a of the resistor 61, 51b, the potential difference signal V _MN representing the voltage difference between the neutral point of 51c _{is, V MN = V M -V N} = (1/3) (E U + E _V + E _W), and the armature coils 51a, 51b, the induced voltage of 51c is E _U, E _V, it is found to be proportional to the sum of E _W.

Here, the armature coils 51a, 51b, 5
Induced voltage E _U of 1c, E _V, E _W becomes a phase different trapezoidal waveform for each 120 deg, the potential difference signal V _MN is three times the fundamental of the induced voltage E _U, E _V, with respect to E _W It becomes a substantially triangular wave having a wave frequency component. The peak point of the triangular wave of the potential difference signal _VMN is a switching point of the voltage pattern. Since the amplitude of the peak point of the potential difference signal V _MN fluctuates depending on the rotation speed, the integration amplifier circuit 62
The potential difference signal V _MN from the second is converted into a substantially sinusoidal integration signal ∫V _MN
After integration conversion to dt, the zero-cross comparator 63 detects and amplifies the zero-cross point of the integration signal Int,
After being converted into a square wave by the photocoupler 64, the above-described position signal Sint is output to the microcomputer 54.

Next, in the microcomputer 54, as shown in FIG.
After receiving the square wave position signal Sint from the rotational position detector 53 at the interrupt terminal 70 (step S01), one high state and one low state are each set as one pulse unit, and each pulse unit is used. First, the pulse width T in the high state or the low state (FIG. 10) is detected by the T measuring section 71 (step S02). On the other hand, a target pulse width Tx (FIG. 10) given from an external input means 72 such as an operation panel is received into the microcomputer 54 through a target Tx input unit 73. Then, the pulse width T detected by the T measuring unit 71 is compared with the target pulse width Tx received by the target Tx input unit 73 (Step S03), and the speed calculation unit 74 determines a desired rotation speed according to the comparison result. Calculate. Further, according to the calculation result in the speed calculation unit 74, the desired inverter voltage V
Is determined by the inverter voltage V determination unit 75. After the desired rotation speed and inverter voltage V are obtained in this way, PWM modulation is performed by the PWM modulator 76 so that the integral value becomes a sine wave, and the obtained PWM pulse-like switching signal is converted into an inverter waveform signal output unit. The signal is output to the drive circuit 55 through 77.

The drive circuit 55 includes the microcomputer 5
4 receives the switching signal from
Output a commutation control signal to the bases of the transistors 60a to 60f. Then, the transistors 60a to 60f of the inverter unit 60 are sequentially turned on and off to switch the voltage pattern for the armature coils 51a, 51b, 51c (steps S04 to S06).

[0011] Thus, the brushless DC motor, E _U armature coils 51a, 51b, the induced voltage of 51c,
E _V, position signal Si representing the rotational position of the rotor 50 from E _W
nt, and the inverter unit 60 outputs the position signal S
The voltage pattern of the armature coils 51a, 51b, 51c is switched by int. This voltage pattern switching process is performed until the time Tm1 at which the pulse width T detected by the microcomputer 54 is determined to be equal to the target pulse width Tx as shown in FIG. 10, and thereafter, the target pulse width Tx is changed to the pulse width Tx. As a result, the steady driving of the brushless DC motor by the inverter unit 60 is continued.

As described above, when a load having a large torque fluctuation range such as a compressor of various air conditioners is driven by using a brushless DC motor driven and controlled by the brushless DC motor drive control device, the brushless DC motor is driven. If the performance of the motor is sufficiently exhibited, effective operation can be performed within an operation area required for the compressor, for example, a maximum pressure limit, a maximum inverter voltage limit, and a maximum frequency limit as shown in FIG. It is.

[0013]

SUMMARY OF THE INVENTION General brushless D
In the C motor drive control device, as is apparent from FIG.
Rotor 5 for armature coils 51a, 51b, 51c
The detection of the relative rotation position of 0 is performed by extracting a signal from the high-power section of the inverter section 60, and therefore, the structure is such that noise is easily superimposed on the position signal Sint and the like. Then, when a sudden and large noise is generated, abnormality occurs in the determination and control in the microcomputer 54.
Then, the phase of the inverter current waveform is suddenly shifted, the amplitude of the inverter current waveform is rapidly increased, and an overcurrent flows to the inverter unit 60 soon. As a result, inverter control becomes impossible and the brushless DC motor stops, and in the worst case,
Overheating of the inverter unit 60 or its peripheral components may cause burning or destruction. Therefore, the position signal S
It is important to reduce the influence of noise on int.

In view of such circumstances, the position signal Si in the microcomputer 54 is reduced so as to reduce the influence of noise as much as possible.
Proposal of ignoring a signal change in a predetermined portion within each pulse width T of each pulse of nt to cancel noise in the predetermined portion (FIG. 12A)
(B)) is performed. In this proposed example, specifically, as shown in FIG.
Each time the leading edge and trailing edge of the high state of nt are given, the respective position signals S
The pulse width T is continuously detected for the high state and the low state of int. Here, if the detected value of the n th pulse width T and Tn, value of the pulse width T that is detected by the microcomputer 54 is _{"..., T n-1, T} n, T n + 1, ... " and so on Will be given. However, when the inverter is driven, the pulse width T may change every moment, so that “T _n−1 ”, “T _n ”, and “T _{n + 1} ” do not always match. Therefore, the n-th position signal Sint
When a middle of the pulse receiving state, the value T _n of the pulse width T of the n-th pulse of the position signal Sint this time
Does not necessarily coincide with the previous value T _n−1, and FIG.
As described above, unless the time Tm2 elapses, the microcomputer 54 cannot recognize it. However, in a normal inverter drive, the pulse width T (..., T _n−1 , T _n , T _{n + 1} ,
...) Are relatively gradual, and the difference between the pulse width T of one pulse and the pulse width T of the next succeeding pulse does not exceed 25%. That is, the value of the pulse width T of the sequentially given position signal Sint “.
T _n−1 , T _n , T _{n + 1} ,... ”Normally satisfy the following conditions.

: (3/4) × T _n-1 <T _n <(5/4) × T _n-1 (3/4) × T _n <T _{n + 1} <(5/4) × T _n Considering this, as shown in FIG. 12B, in the n-th pulse (low state in FIG. 12B), even if the value T _n of the pulse width T is unknown at this time, Value T
_{Since n-1} is known at the present time, the transition of the position signal Sint (in this case, the trailing edge) is set to the origin "0", and the recognition of the trailing edge is performed at the time of "(3/4) * _Tn-1 ". It is sufficient to go after Tm3. Therefore, n
In times th pulse (the value T _n of the pulse width T of the case is not known at the present time), until the time Tm3 of "(3/4) × T _n-1" after a lapse of time "0" of the transition Between
It is possible to ignore any signal change, and it is possible to cancel the noise in this portion. FIG.
In (B), “(3) × T _n−1 ” and “(3
/ 4) × T _n−1 ”is cancelled until time Tm3.

However, even in such a proposal example,
If noise enters after the time Tm3 of "(3/4) * Tn _-1 ", it is impossible to cancel this noise. Then, the time T of this “(3/4) × T _n−1 ”
likely to lead to a malfunction detecting an erroneous T _n by m3 subsequent noise, can result in turn inverter stop.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a brushless DC motor drive control method and an apparatus therefor which can eliminate the influence of noise of a position signal given to a microcomputer.

[0018]

Means for Solving the Problems In order to solve the above problems,
The invention according to claim 1 is a brushless DC motor drive control method for providing a voltage pattern based on a position signal at which a level switches according to a relative rotation position between a rotor and a stator of the brushless DC motor. Repeating the step of detecting the level at a second time when a predetermined delay time has elapsed from a first time at which a transition appearing in the position signal is detected, while updating the first time, the first time If the level is the same before and after each update,
The voltage pattern is controlled based on the pulse width of the pulse having the latest detected transition as the leading edge while ignoring the pulse having the latest detected transition as the leading edge.

According to a second aspect of the present invention, the brushless DC motor drive control method according to the first aspect is executed only in a steady operation after the synchronous operation at the start of the brushless DC motor drive control device is completed. , The level of the last position signal during the synchronous operation is defined as an initial value which is the level before the first time point after the start of the steady operation.

According to a third aspect of the present invention, in the brushless DC motor drive control method according to the first or second aspect, the pulse width is detected by x times the pulse width detected immediately before. Double to y times (0 <x <y <1)
Is performed ignoring the transition until the time elapses.

According to a fourth aspect of the present invention, there is provided a brushless DC
In a brushless DC motor drive control device for providing a voltage pattern based on a position signal at which a level switches according to a relative rotation position between a rotor and a stator of a motor, a first state in which a transition appearing in the position signal is detected. The step of detecting the level at a second time when a predetermined delay time has elapsed from the time is repeated while updating the first time, and the level is inverted before and after each update of the first time. Pulse inversion confirming means for confirming whether or not the pulse has been inverted, and when the pulse inversion confirmation means has confirmed that the pulse has been inverted, the speed is determined based on the pulse width of the pulse whose latest detected transition is the leading edge. While performing the operation,
A speed calculation unit for performing a speed calculation while ignoring a pulse having the latest detected transition as a leading edge when the pulse inversion checking unit confirms that the speed is not inverted; and a speed calculation unit for the speed calculation unit. A signal output unit for outputting a predetermined control signal for controlling the voltage pattern based on the result.

According to a fifth aspect of the present invention, there is provided the brushless DC motor drive control device according to the fourth aspect, wherein the brushless DC motor drive control device includes the brushless DC motor drive control device.
A mode switching means for switching between a synchronous operation mode for the synchronous operation at the time of starting the C motor drive control device and a steady operation mode for the steady operation after the synchronous operation has been completed, and the synchronous operation mode by the mode switching means. Synchronous operation instructing means for giving an instruction for synchronous operation to the speed calculating unit when the mode is switched, wherein the pulse inversion confirming means is provided only when the mode is switched to the steady operation mode by the mode switching means. The synchronous operation instructing means sets the level of the last position signal at the time of the synchronous operation as an initial value which is the level before the first time point after the start of the steady operation. It has been stipulated.

[0023]

According to the first and fourth aspects of the present invention, the level of the position signal is detected at a second time when a predetermined delay time has elapsed from the second time when the transition appearing in the position signal is detected. This is repeated for each update at the first point in time. If the level is not inverted before and after the update, it is determined that the most recently detected transition is noise and is ignored. It determines that the most recently detected transition is the leading edge of the pulse of the legitimate position signal, and controls the voltage pattern based on the pulse width of the pulse.
As a result, all noise having a pulse width shorter than the predetermined delay time can be canceled.
Malfunction of the C motor can be prevented.

According to the second and fifth aspects of the present invention,
During synchronous operation at the time of starting the brushless DC motor drive control device, drive control is performed according to a predetermined general method or the like, and according to claims 1 and 4 only during steady operation after completion of synchronous operation. The operation which ignores such noise is performed. In this case, since the level of the last pulse in the synchronous operation for the position signal is defined as the initial value of the level of the first pulse at the start of the steady operation, the operation from the synchronous operation to the noise ignoring operation in the steady operation is performed. Migration can be performed efficiently.

According to the third aspect of the present invention, in parallel with the operation of the first or second aspect, recognition of any pulse fluctuation is ignored for a part of the period of each pulse of the position signal. Therefore, not only noise having a pulse width shorter than the predetermined delay time described above but also noise having a longer pulse width can be canceled. Therefore, malfunction of the brushless DC motor can be more reliably prevented. In this case, based on the point in time when it is determined that the transition of the normal position signal as a result of ignoring noise having a short pulse width according to claim 1 or claim 2, the noise is disciplined in a period in which recognition of any pulse fluctuation is ignored. Because it is possible, the period during which the noise is ignored can be accurately regulated.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, when a predetermined process is performed using a microcomputer (hereinafter simply referred to as a microcomputer), various arithmetic operations and signal input / output operations are performed while being regulated by a clock signal having a predetermined cycle. Done.
Therefore, in the case where a predetermined interrupt processing is performed in response to a predetermined signal input in the microcomputer, a certain “delay time” from the time of the signal input due to the cycle of the clock signal, other interrupt processing, register saving, etc. After the elapse, the predetermined interrupt processing is completed. The present invention
By utilizing the occurrence of such a "delay time", it is intended to cancel noise generated within the delay time. Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the brushless DC motor drive control device according to this embodiment has a position signal Sin of a microcomputer.
The trailing edge te1, t of the signal is input to the input port of t.
ed, te2, te3, ... or leading edge l
Every time e1, le2, led, le3, ... are input,
The level of each pulse of the position signal Sint at that time, that is, the high / low state α1, α2, αd1, α3,
By detecting α4, α5, αd2, α6,... and determining whether or not the position signal pulse previously detected is normally inverted with respect to the high / low state, the position signal Sint is input to the input port. Trailing edge te of the signal
.. Or the leading edges le1, le2, led, le3,... Are determined to be due to normal position signals or to noise, and are determined to be due to noise. In this case, the signal relating to the trailing edge ted or the leading edge led is canceled. In this embodiment, the noise cancellation in the above-mentioned proposal example is also executed.

FIG. 2 is a block diagram showing one embodiment of the brushless DC motor drive control device of the present invention.
That is, this brushless DC motor drive control device
A motor for driving and controlling a brushless DC motor 11 including a rotor 10 having a plurality of permanent magnets and a stator 1 having armature coils 1a, 1b, and 1c connected in three-phase Y connection. A rotational position detector 2 for detecting a relative rotational position of the rotor 10 with respect to the child coils 1a, 1b, 1c, and an armature receiving a position signal Sint from the rotational position detector 2 representing the rotational position of the rotor 10. Coils 1a,
A microcomputer 4 for switching a voltage pattern with respect to 1b and 1c, a drive circuit 5 for receiving a switching signal from the microcomputer 4 and outputting a commutation control signal for switching and controlling the voltage pattern of the armature coils 1a, 1b and 1c; An inverter unit 6 receives the commutation control signal from the circuit 5 and switches the voltage pattern of the armature coils 1a, 1b, 1c.

The rotational position detector 2 includes armature coils 1a,
The resistors 21a, 2 connected in three phases in parallel with 1b, 1c
1b, 21c, an integrating amplifier 22 for integrating and amplifying the voltage V _MN at the neutral point M of the resistor circuit 21, and a pulsing circuit for pulsating the integrated signal Int from the integrating amplifier 22. And a circuit 23.

Here, the integrating amplifier circuit 22 includes an amplifier IC
The voltage V _MN of the neutral point M of the resistance circuit 21 is connected to the inverting input terminal
And ground GND to the non-inverting input terminal.
And a resistor R1 and a capacitor C1 are connected in parallel between the output terminal and the inverting input terminal. That is, the neutral point M of the armature coils 1a, 1b, 1c is
Since it is connected to the non-inverting input terminal of the amplifier IC1 via the ND, the integrating amplifier circuit 22 determines the voltage at the neutral point M of the resistance circuit 21 and the neutral point N of the armature coils 1a, 1b, 1c.
, A potential difference signal V _MN representing a potential difference with respect to the potential difference voltage is detected, and the potential difference signal V _MN is integrated to output an integrated signal Int.

The pulsing circuit 23 includes an amplifier IC2
And a photocoupler PC. Among them, in the amplifier IC2, the integration signal In from the integration amplification circuit 22 is output.
While t is input to the inverting input terminal, the non-inverting input terminal of the amplifier IC2 is connected to the ground GND via the resistor R2, and is pulled up by the resistors R3 and R4. Further, between the output terminal of the amplifier IC2 and the non-inverting input terminal, the light emitting portion PCa of the photocoupler PC and the resistor R3 are sequentially connected in series. The resistor R4 pulls up a connection point between the light emitting unit PCa and the resistor R3. The photocoupler PC is for supplying the position signal Sint to the microcomputer 4 while ensuring electrical insulation between the high-voltage section and the low-voltage section. Are connected in series between predetermined voltages, and a signal at this connection point is supplied to the microcomputer 4. The amplifier I
C2 and resistors R2 to R4 constitute a zero cross comparator.

The microcomputer 4 includes a CPU, a ROM, and a RAM.
And the like, and all the arithmetic or control operations are executed by software stored in a ROM or the like in advance. As a functional element of the microcomputer 4, the setting is switched between a synchronous operation mode as an initial operation and a position detection operation mode (a steady operation mode) as a normal operation in accordance with the state of a position signal Sint given from the rotational position detector 2. Mode switching means 31, a synchronous operation instruction means 32 for giving a synchronous operation instruction when the synchronous operation mode is set by the mode switching means 31, and a position when the position detection operation mode is set by the mode switching means 31. A pulse inversion confirming means 33 for confirming a normal high / low inversion state of the pulse of the signal Sint, and a high / low inversion state for each pulse only when the normal high / low inversion state is confirmed by the pulse inversion confirmation means 33 T measuring unit 34 for measuring pulse width T in the low state (see FIG. 10)
A target Tx input unit 36 for receiving a target pulse width Tx (see FIG. 10) provided from an external input means 35 such as an operation panel into the microcomputer 4, a pulse width T detected by the T measuring unit 34, and a target Tx input. A speed calculator 37 for calculating a desired rotation speed in accordance with a difference from the target pulse width Tx received by the unit 36, and an inverter voltage V determiner for determining a desired inverter voltage V in accordance with the calculation result in the speed calculator 37 38, a PWM modulator 39 that modulates and generates an appropriate PWM pulse wave based on a desired rotation speed and an inverter voltage V, and an inverter waveform signal output unit that outputs an appropriate switching signal to the drive circuit 5 based on the PWM pulse wave. 40.

Since the inverter section 6 has the same configuration as the inverter section 60 shown in FIG. 8, detailed description will be omitted.

In the above configuration, when the brushless DC motor is driven according to the position detection, the U-phase, V-phase, and W-phase induced voltages E of the armature coils 1a, 1b, 1c.
_U , E _V and E _W are, as shown in FIGS.
A trapezoidal waveform having a different phase every 20 deg. The amplifier IC1 of the rotational position detector 2 shown in FIG. 2 includes the voltage at the neutral point M input to the inverting input terminal and the armature coil 1a input to the non-inverting input terminal of the amplifier IC1. , 1b, 1c, a potential difference signal V _MN (FIG. _3D ) representing a potential difference from the voltage V _{N at} the neutral point N is detected, and the potential difference signal is integrated to obtain an integrated signal Int (FIG. 3E )) Is output. This integration signal Int has a substantially sinusoidal waveform having a frequency three times the rotation frequency. Then, the pulsing circuit 23 amplifies the integrated signal Int input to the inverting input terminal of the amplifier IC2 to a predetermined amplitude, and subjects the amplified integrated signal Int to photoelectric conversion by the photocoupler PC and shapes the integrated signal Int. The signal is output as a signal Sint (FIG. 3F).

Next, the position signal S from the rotational position detector 2
The int is input from the interrupt terminal 30 of the microcomputer 4 to the mode switching means 31. Here, first, when the brushless DC motor drive control device is started, as shown in FIG.
Is gradually increased from the stop state, so that the pulse width T of the position signal Sint applied to the microcomputer 4 gradually decreases (ie, increases) until the stable state S1 is reached. For this reason, the mode switching means 31 in the microcomputer 4 sets the synchronous operation mode for a while after the activation of the brushless DC motor drive control device. That is, in step S11 in FIG. 5, first, a variable “Portbuf” indicating whether each pulse of the position signal Sint is in a high state or a low state is initialized, and then the position signal Sin is set.
Each time t is input to the interrupt terminal 30, the pulse width T is detected (step S12), and the pulse width T at this time is stored in the stack (step S13). At this time, the synchronous operation instructing means 32, which has been set to the synchronous operation mode by the mode switching means 31, first supplies a signal indicating that the operation is synchronous to the speed calculating section 37, and based on the signal at this time, the inverter voltage V determining section The desired inverter voltage V is determined by 38 to obtain the desired rotation speed and inverter voltage V.
Thereafter, PWM modulation is performed by the PWM modulator 39 so that the integral value becomes a sine wave, and the PWM pulse-like switching signal obtained here is converted into an inverter waveform signal output unit 4.
0 to the drive circuit 55. Based on the switching signal obtained by such an operation, the inverter unit 6 controls the rotor 10 of the brushless DC motor 11.
The synchronous operation is continued until the rotation speed of the motor becomes stable at a predetermined level. In addition, since the inverter drive in this synchronous operation mode may be drive-controlled in accordance with a general V / F constant control method, a detailed description of the operation will be omitted.

While the synchronous operation is being performed, the mode switching means 31 of the microcomputer 4 keeps detecting the pulse width T of the position signal Sint repeatedly input in the high / low state.
Position signal Si input continuously plural times (for example, four times)
When all the pulse widths T of nt become the same (step S14), the rotation speed of the rotor 10 is in a stable state S1 (FIG. 4).
Is determined, and the operation proceeds to an operation for completing the synchronous operation. A variable “port Sint” indicating whether the pulse of the position signal Sint at this time is in a high state or a low state
Is substituted for the above-described variable “Portbuf” (step S15).

After completion of the synchronous operation, the mode switching means 31 is specifically realized by switching from the synchronous operation mode to the position detection operation mode. At this point, the synchronous operation instruction means 32 stops functioning. Note that the aforementioned step S
As described in 15, the high / low state of the pulse of the last position signal Sint in the synchronous operation mode is assigned to the variable “Portbuf” as an initial value during the position detection operation.

Next, the operation in the position detection operation mode after the completion of the synchronous operation will be described. As shown in FIG. 6, first, in step S21, the pulse inversion confirming means 33 of the microcomputer 4 receives the position signal Si inputted through the interruption terminal 30 through the interruption terminal 30.
Whether the pulse of the position signal Sint immediately after detecting the pulse transition of nt (trailing edge and leading edge) is in a high state or a low state is detected, and this is substituted for a variable “port Sint”. Then, it is determined whether or not this variable “port Sint” matches the previously defined variable “Portbuf” as the previous value (step S22).

Here, when a predetermined process is performed using the microcomputer 4, various arithmetic operations and signal input / output operations are performed while being regulated by a clock signal having a predetermined cycle.
Therefore, when a predetermined interrupt process is performed in response to a signal input to the microcomputer 4 as an interrupt, the interrupt process is executed in synchronization with the clock signal. Due to processing, register saving, and the like, predetermined interrupt processing is completed after a certain “delay time” has elapsed from the time of signal input. Therefore, the process of step S22 is performed after a certain “delay time” has elapsed after the process of step S21 described above is performed. That is, as shown in FIG. 7, even if the pulse transitions le, ted and te are detected in order in the position signal Sint (step S21), each pulse transition l
Immediately after e, ted, and te, the high / low state of the pulse of the position signal Sint at α is detected (step S22).
By this time, a delay time ΔT occurs. Here, the position signal S
When noise is superimposed on int, this noise appears as a pulse wave of an extremely short width starting from the pulse transition ted. Therefore, if the pulse width of the noise is shorter than the delay time ΔT, even if the noise is detected as the pulse transition ted in step S21,
When the high / low state of the pulse is detected in the next step S22, the position signal Sint has returned from the noise state to the steady state. That is, at time Tn2 in FIG. 1, the leading edge le1
Is detected (step S21), and it is confirmed that the pulse input at that time is in a high state like α2 (step S22). Then, at the time Tnd1, noise having an extremely short pulse width is mixed and Trailing edge t
When ed appears (step S21), immediately after that, a high / low state of the pulse is detected (step S22).
.Alpha.d1 is in the high state. Similarly, at time Tn5 in FIG. 1, after detecting the trailing edge te3 (step S21), it is confirmed that the pulse input at that time is in a low state like α5 (step S22). Next, at the time Tnd2, if the leading edge led appears due to noise of an extremely short pulse width mixed therein (step S21), immediately after that, when the high / low state of the pulse is detected as step S22, αd2 is set to the high state. It will be.

As described above, in step S22, α
If 2 (ie, the previous value “Portbuf”) and αd1 (ie, the current value “Port Sint”) match, it can be determined that the pulse transition input this time is due to noise. Therefore, when it is determined that they coincide with each other, it is not preferable to perform inverter control based on such noise. Therefore, the speed calculation unit 37, the inverter voltage V determination unit 38, the PWM modulation unit 39, and the inverter waveform signal While the steady operation of the inverter specified through the output unit 40 is simply continued, the interrupt processing in step S21 is again waited. The delay time Δ from step S21 to step S22
It has been found that T is usually several μs. For this reason, all noise having a pulse width of less than several μs can be canceled.

Further, using a high-performance microcomputer,
If the delay of s does not occur, if a delay is created using a software NOP instruction or the like, it is possible to control how many μs the time of several μs is set.

On the other hand, if it is determined in step S22 that the previous value "Portbuf" and the current value "port Sint" do not match, the pulse input this time is not due to noise, but the normal position signal Sint.
Pulse.

In this case, in step S23, the current value "port Sint" is substituted for "Portbuf" in order to use it next time as the previous value.

Next, in step S24, the pulse width T (FIG. 10) of the position signal Sint input this time is detected by the T measuring section 34. On the other hand, a target pulse width Tx (FIG. 10) provided from external input means 35 such as an operation panel is received into the microcomputer 4 through a target Tx input unit 36.
Then, the pulse width T detected by the T measuring unit 34 and the target Tx
The target pulse width Tx received by the input unit 36 is compared with the target pulse width Tx (step S25), and the speed calculation unit 37 calculates a desired rotation speed according to the comparison result. In addition, according to the calculation result in the speed calculation unit 37, the desired inverter voltage V
Is determined by the inverter voltage V determining unit 38 (steps S26 and S27). At this time, in the calculation of the rotation speed and the determination of the inverter voltage V, a predetermined phase correction is also performed as shown in FIG. And PW
PWM by the M modulator 39 so that the integral value becomes sinusoidal.
The modulation is performed, and the PWM pulse-like switching signal obtained here is output to the drive circuit 5 through the inverter waveform signal output unit 40 (step S28).

The drive circuit 5 receives a switching signal from the microcomputer 4 and outputs a commutation control signal to the base of each of the transistors 6 a to 6 f of the inverter unit 6. Then, the transistors 6a to 6f of the inverter section 6 are sequentially turned on and off as shown in FIGS. 3H to 3M to switch the voltage pattern for the armature coils 1a, 1b, 1c. Such voltage pattern switching processing is performed until the time Tm1 at which the pulse width T detected by the microcomputer 4 is determined to be equal to the target pulse width Tx as shown in FIG. 10, and thereafter, the target pulse width Tx is changed to the pulse width Tx. As a result, the steady driving of the brushless DC motor by the inverter unit 6 is continued.

In parallel with the above operation, FIG.
The processing in the proposal example shown in (B), that is, with respect to the pulse width T _n-1 of the previous pulse in the position signal Sint, from “( _１ ／) × T _n−1 ” to “(3/4) × T _n Until the time point Tm3 of " _-1 ", no signal change is accepted, and noise having a long pulse width is canceled in this portion. However, at this time, “(1/2) × T
_n−1 ”and“ (3/4) × T _n−1 ”, the starting point of the period is“ port Sin ”in step S22 in FIG.
"t" may not be equal to "Portbuf" of the previous pulse, and may be an input time point of the pulse transition determined to be a pulse transition of the normal position signal Sint. As a result, it is possible to eliminate the influence of noise even in the processing as in the proposed example.

As described above, in addition to the noise canceling process in the proposed example, when each pulse of the position signal Sint is input, each pulse transition is detected and immediately after that, the high / low state of the pulse is detected. By utilizing the fact that the delay time ΔT occurs during the delay, it is possible to cancel all noises with a pulse width less than the delay time ΔT, so that the microcomputer 4, the drive circuit 5, and the inverter unit 6 malfunction or stop the inverter. Can be prevented.

In the above embodiment, the integration signal I
Although the time until the voltage pattern is switched from the position signal Sint based on nt is adjusted, the integration signal I
Instead of nt, a potential difference signal based on the neutral point of the resistance circuit 21 in the rotational position detector 2 can be used as it is.

[0049]

According to the first and fourth aspects of the present invention, the level of the position signal is changed at a second time when a predetermined delay time has elapsed from the second time when the transition appearing in the position signal is detected. This is repeated for each update at the first point in time. If the level is not inverted before and after the update, it is determined that the most recently detected transition is noise, and this is ignored. If so, the latest detected transition is determined to be the leading edge of the pulse of the legitimate position signal, and the voltage pattern is controlled based on the pulse width of the pulse. All width noise can be canceled. Therefore, malfunction of the brushless DC motor can be prevented.

According to the second and fifth aspects of the present invention, during the synchronous operation at the time of starting the brushless DC motor drive control device, the drive is controlled according to a predetermined general method or the like. When performing the operation of ignoring the noise according to claims 1 and 4 only at the time of the steady operation after the end, the level of the last pulse at the time of the synchronous operation with respect to the position signal at the start of the steady operation is determined. Since it is defined as the initial value of the level of the first pulse, the transition from the synchronous operation to the noise ignoring operation in the steady operation can be performed efficiently.

According to the invention described in claim 3, according to claim 1
In parallel with the operation of claim 2, since recognition of any pulse fluctuation is ignored for a part of the period of each pulse of the position signal, noise having a pulse width shorter than the predetermined delay time is ignored. Not only that, but also noise with a longer pulse width can be all cancelled. Therefore, malfunction of the brushless DC motor can be more reliably prevented.
In this case, based on the point in time when it is determined that the transition of the normal position signal as a result of ignoring noise having a short pulse width according to claim 1 or claim 2, the noise is disciplined in a period in which recognition of any pulse fluctuation is ignored. Because it is possible, the period during which the noise is ignored can be accurately regulated.

As described above, it is possible to provide a brushless DC motor drive control method and apparatus which are hardly affected by noise.

[Brief description of the drawings]

FIG. 1 is a signal waveform diagram showing a state in which noise is superimposed on a position signal given to a microcomputer.

FIG. 2 is a block diagram showing a brushless DC motor drive control device according to one embodiment of the present invention.

FIG. 3 is a diagram showing signal waveforms at various parts of the brushless DC motor drive control device.

FIG. 4 is a diagram showing a change in the number of revolutions of a rotor in a synchronous operation at the time of activation of a brushless DC motor drive control device and a subsequent position detection operation.

FIG. 5 is a flowchart showing a synchronous operation operation in one embodiment of the present invention.

FIG. 6 is a flowchart showing a position detection driving operation in one embodiment of the present invention.

FIG. 7 is a diagram illustrating a delay time generated from when a position signal is supplied to a microcomputer to when a high / low state of each pulse of the position signal is detected.

FIG. 8 is a block diagram showing a conventional brushless DC motor drive control device.

FIG. 9 is a flowchart showing an operation of inverter control in the microcomputer.

FIG. 10 is a waveform chart showing a position signal given to the microcomputer.

FIG. 11 is a diagram illustrating a relationship between an operating frequency and a torque of a brushless DC motor.

FIG. 12 is an enlarged waveform diagram showing a position signal given to a microcomputer.

[Explanation of symbols]

1 stator, 1a, 1b, 1c armature coil, 2 rotational position detector, 3 level detector, 4 microcomputer, 5
Drive circuit, 6 inverter section, 6a to 6f transistor, 7 current sensor, 10 rotor, 11 brushless DC motor, 21 resistor circuit, 21a, 21b, 21
c resistance, 22 integrating amplifier circuit, 23 pulse circuit, 3
1 cycle calculator, 32 calculator, 33 inverter mode selector, 34 speed calculator, 35 speed controller, 41
Level determination unit, 42 PWM unit, T1 phase correction timer, T2 cycle measurement timer, 45 current change determination means,
46 Stop instruction means, AN0, AN1, AN2 analog input terminals, Iu, Iv, Iw current, Sint position signal

Claims (5)

[Claims] A brushless DC motor rotor (10)
A brushless DC motor drive control method for providing a voltage pattern based on a position signal (Sint) whose level switches according to a relative rotational position between the motor and the stator (1), and appears in the position signal (Sint). Transition (te1, le
1, ted, te2, le2, te3, led, le
,...) From a first point in time when a predetermined delay time (Δ
The step of detecting the level at a second time point after T) has elapsed is repeated while updating the first time point. If the level is the same before and after the update at the first time point, The most recently detected transition (ted, le
While the pulse with d) as the leading edge is ignored, if different, the most recently detected transition (te1, le)
1, te2, le2, te3, le3,...) As the leading edge, based on the pulse width (T) of the pulse.
A brushless DC motor drive control method, comprising controlling the voltage pattern. 2. The brushless DC motor drive control method according to claim 1, wherein the method is executed only in a steady operation after the synchronous operation at the time of starting the brushless DC motor drive control device is completed. Wherein the level of the position signal (Sint) is defined as an initial value which is the level before the first time point after the start of the steady operation. 3. The brushless DC motor drive control method according to claim 1, wherein the detection of the pulse width is x times the pulse width (T _n-1 ) detected immediately before. To y times (0 <x <y <
A brushless DC motor drive control method, wherein the transition is performed ignoring the transition until 1) elapses. 4. A rotor for a brushless DC motor (10).
A brushless DC motor drive control device that provides a voltage pattern based on a position signal (Sint) whose level switches according to a relative rotation position between the motor and the stator (1). te1, le
1, ted, te2, le2, te3, led, le
,...) From a first point in time when a predetermined delay time (Δ
The step of detecting the level at a second time point after the elapse of T) is repeated while updating the first time point.
A pulse inversion confirming means (33) for confirming whether or not the level has been inverted before and after each update at the time point of; and a case where the pulse inversion confirmation means (33) has confirmed that the level has been inverted. , The most recently detected transition (te1, l
e1, te2, le2, te3, le3,...) perform the speed calculation based on the pulse width (T) of the pulse having the leading edge, and the pulse inversion confirming means (33).
When it is confirmed that the inversion has not occurred, the speed calculation unit (3) that performs the speed calculation while ignoring the pulse having the latest detected transition (ted, led) as the leading edge.
7) and a signal output unit (40) for outputting a predetermined control signal for controlling the voltage pattern based on the speed calculation result of the speed calculation unit (37). 5. The brushless DC motor drive control device according to claim 4, wherein the brushless DC motor drive control device includes: a synchronous operation mode for a synchronous operation performed when the brushless DC motor drive control device is started; A mode switching means (31) for switching between a steady operation mode and a steady operation mode after the synchronous operation is completed; and the speed calculation unit (37) when the mode is switched to the synchronous operation mode by the mode switching means (31). ), The synchronous operation instructing means (3)
2), wherein the pulse inversion confirming means (33) is operated only when the mode switching means (31) switches to the steady operation mode, and the synchronous operation instruction means (32) And the level of the last position signal (Sint) at the time of the synchronous operation is defined as an initial value which is the level before the first time point after the start of the steady operation. Brushless DC motor drive control device.