JPH1023783A - Dc brushless motor drive method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and accurately perform the judgment of the step-out condition of a DC brushless motor where the commutation of the drive current to a drive winding is controlled by detecting the position of a rotor, based on the voltage induced in the drive winding of a motor. SOLUTION: A measuring means 61 measures the signal change time interval values tn between rotor position pulse signals ZA-ZC in order, and a filtering means 62 gets the filtering value Ta which reflects the signal time change interval values tn-1 , tn-2 ..., measured in the past. An abnormality judging means 63 judges the rotation of a DC brushless motor 10 to be abnormal, in the case that the signal change time interval tn measured at that time is over the specified range decided based on the filtering value Tn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct current (DC) system which detects a position of a rotor based on a voltage induced in a driving winding of a motor and controls commutation of a driving current to the driving winding. The present invention relates to a brushless motor driving device.

[0002]

2. Description of the Related Art A synchronous motor is first started and accelerated by giving an external synchronous signal to a DC brushless motor. When a permanent magnet rotor reaches a predetermined rotational speed, a sufficient amount of reverse winding is generated from each drive winding. Once the induced voltage can be obtained, the position of the permanent magnet rotor is detected by this back-induced voltage, and based on this, the drive current to each drive winding is commutated and sensorless operation is performed to rotate the permanent magnet rotor. 2. Description of the Related Art A DC brushless motor driving device capable of switching is known.

In the case of control of the type in which the position is detected from the back-induced voltage induced in the drive winding, a step-out state that occurs when the position of the mover cannot be accurately detected, such as when a sudden change in load occurs, is detected. Has the problem that it is difficult. For this reason, Japanese Patent Application Laid-Open No. Hei 5-236788 discloses a configuration in which a step-out is established by using a change in an output signal from a back electromotive force detector deviating from a specific range from the energization switching. Japanese Patent Application Laid-Open No. 6-253580 discloses a reference time setting means for setting a reference time for determination with respect to a positive / negative change time of an induced voltage from a set rotational speed, and a reference time for determination and a positive / negative change time of an induced voltage. Compare,
There has been proposed a configuration in which comparison means for outputting a signal for turning off the motor when the change time is out of the range of the reference time for determination is provided.

[0004]

However, since the DC brushless motor fluctuates even during one rotation, the former configuration evaluates the current position detection signal time based on the immediately preceding position detection signal time. Therefore, a normal signal may be erroneously determined to be abnormal. Further, in the latter configuration, since the determination reference time is generated based on the rotation speed command, if the rotation speed command is greatly changed, the determination reference time will also be greatly changed. Cannot follow up, so that a step-out determination is made due to the response delay. Furthermore, in any case, both have a problem that they are not feasible due to the complicated configuration.

An object of the present invention is to provide a brushless DC motor in which the position of a rotor is detected based on a voltage induced in a driving winding of the motor to control the commutation of a driving current to the driving winding. It is an object of the present invention to provide a DC brushless motor driving method and apparatus capable of easily and accurately determining a step-out state.

[0006]

According to a first aspect of the present invention, there is provided a DC brushless motor comprising: a plurality of rotations indicating position information of a rotor based on voltages induced in respective drive windings; A DC brushless motor driving method in which a rotor position pulse signal is obtained and commutation control of a drive current to the drive winding is performed by the rotor position pulse signal; a signal change time between the rotor position pulse signals; The interval values are sequentially measured, and a filtering process of the signal change time interval value is performed based on the measurement result. When the measured signal change time interval value exceeds a predetermined range determined based on the filtering process result, That is, it is determined that the rotation of the DC brushless motor is abnormal. Here, the signal change time interval is measured by measuring a timing difference between each change point of the rotor position pulse signal.

A second aspect of the present invention is characterized in that position detecting means for outputting a plurality of rotor position pulse signals based on voltages induced in respective drive windings of the DC brushless motor, A DC brushless motor driving device comprising: an energization switching means for controlling commutation of a drive current to the drive winding in response to the output of the rotor position pulse signal. Measuring means for sequentially measuring the signal change time interval value, filtering means for filtering the signal change time interval value in response to the measurement means, signal change time interval value obtained by the measurement means, and the filtering The signal change time interval value is determined based on the filtering result in response to the filtering result obtained by the means. Lies in having an abnormality judging means for outputting a rotation abnormality determination information when exceeding the predetermined range to be.

If the fluctuation speed of the rotation speed of the DC brushless motor, that is, the rotation speed of the rotor is small and the signal change time interval value does not exceed a predetermined range, the rotation abnormality determination information is not output. However, due to rotation fluctuation for some reason, the signal change time interval value, which is the time from the change of one rotor position pulse signal to the change of any other rotor position pulse signal, is changed. If it deviates significantly from the predetermined range, a rotation abnormality determination is made.

[0009]

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

In FIG. 1, reference numeral 10 denotes a three-phase Y-connected four-pole DC brushless motor, and an A-phase drive winding 11;
It comprises a B-phase drive winding 12, a C-phase drive winding 13, and a permanent magnet rotor 14. Since the DC brushless motor 10 has a known configuration, a detailed description of its structure is omitted here.

A DC brushless motor driving apparatus according to the present invention for driving the DC brushless motor 10 is generally indicated by reference numeral 20.
A commutator 21 for commutating the drive current to the motor. The commutator 21 has a known configuration in which switching transistors 22 to 27 and diodes 28 to 33 are connected as shown in the figure. Flow control signals U to Z are provided. The switching transistors 22 to 27 are turned on / off in accordance with the commutation control signals U to Z, whereby commutation of the drive current from the DC power supply 34 to the drive windings 11 to 13 is performed, and the permanent magnet rotor 14 is rotationally driven. Is done.

The DC brushless motor driving device 20 further determines the rotational position of the permanent magnet rotor 14 from the back-induced voltage induced in each of the drive windings 11 to 13 by the rotation of the permanent magnet rotor 14, and determines the rotational position. _A position detection circuit 50 having a known configuration for outputting rotor position pulse signals Z _A , Z _B , and Z _C indicating the results and supplying the signals to the energization switching unit 40 is provided.

FIG. 2 shows the rotor position pulse signals Z _A , Z
_B, the waveform of the Z _C is shown. As can be seen from the waveforms shown in FIG. 2, the rotor position pulse signals Z _A , Z _B , Z _C
Have a phase difference of 120 ° from each other. These rotor position pulse signals Z _A , Z _B , Z _C are input to the energization switching unit 40, where the commutation control signals U to Z for commutation control are performed.
Is provided to the switching transistors 22 to 27. As a result, commutation control is performed so that the drive current to the drive windings 11 to 13 is switched every time the permanent magnet rotor 14 rotates by 120 °, and the DC brushless motor 10 is driven to rotate. Since the configuration of the energization switching unit 40 that operates as described above is also known, the detailed description of the configuration is omitted here.

When a step-out phenomenon occurs in the DC brushless motor 10, the DC brushless motor drive device 20 is provided with a DC brushless motor An abnormal rotation determining unit 60 for determining whether the rotation of the motor has fallen into an abnormal state. The abnormal rotation control unit 60 is configured using a microcomputer having a known hardware configuration, and according to a data processing program for determining abnormal rotation stored in its memory unit (not shown), the rotor position pulse signal Z _A. , Z _B and Z _C are processed to determine whether the rotation of the DC brushless motor 10 has fallen into an abnormal state.

FIG. 1 is a functional block diagram showing the configuration of the abnormal rotation control unit 60. In the abnormal rotation control section 60, the measuring means 61 outputs the rotor position pulse signal Z _A ,
Rotor position pulse signals Z _A , Z _B , in response to Z _B , Z _C
This is for sequentially measuring the mutual signal time change interval value between Z _C. When this is explained with reference to FIG. 2, for example, at time T = T1 first rotor position pulse signal Z _A is if and starts measuring the time that has changed from "0" to "1", then T = because the T2 is the rotor position pulse signal Z _B changes from "0" to "1", time until T1~T2 is measured as signal time variation interval value at that time. Thus, T2 to T3, T3
To T4,... Are sequentially measured as the signal time change interval value, and the measurement time data DT indicating the result is measured by the measurement unit 61.
Output from

The measured time data DT is sequentially input to the filtering means 62. Here, based on the value t _{n of the} currently obtained measured time data DT and the previous filtering result value T _n-1 , the following equation T _n = k • t _n + (1−k) · T _n−1 (1) A filtering process for obtaining the current filtering value T _n is performed. Here, k is a constant and is a value larger than 0 and smaller than 1. (1) As can be seen from the equation, the current filtering value T _n is an average value values of past measuring time value signal time variation interval value in consideration of the data DT, thus properly determining the value of the constant k This makes it possible to determine the value of T _n obtained at that time as a reference data value to be compared with the value of t _n obtained at that time.

The previous filtering value T _n-1 obtained by the filtering means 62 and the measured time data DT indicating the current signal time change interval value t _n measured by the measuring means 61 are inputted to the abnormality judging means 63. Here, a determination based on the following equation: t _n > P × T _n−1 (2) t _n <Q × T _n−1 (3) is performed. Here, P and Q are constants, and P> 1, Q <1. If both equations (2) and (3) are not satisfied, it is determined that the DC brushless motor is rotating stably. On the other hand, equation (2) or (3)
If at least one of the expressions is satisfied, the current signal time change interval value t _n does not fall within a predetermined range determined based on the filtering value T _n−1 , and the DC brushless motor 10 It is determined that the rotation state is abnormal and the motor is out of step. As a result, the abnormality determination means 63
Outputs a stop signal TS for stopping the operation of the DC brushless motor 10 to the control unit 40. As a result, the commutation control is stopped in the control unit 40, and the permanent magnet rotor 1 of the DC brushless motor 10 is stopped.
4 will stop.

FIG. 3 is a flowchart showing a data processing program executed in the abnormal rotation determining section 60. Next, the operation of the abnormal rotation determining section 60 will be described with reference to FIG. When the execution of the data processing program is started, in step 71, an initial value of the filtering value T _n-1 is set. At the very beginning, the value of the signal time change interval value t _n measured at that time is set as the initial value of the filtering value T _n-1 . Next, at step 72, it is determined whether or not any of the rotor position pulse signals Z _A , Z _B , Z _C has changed, that is, whether the level has changed. In step 72, the determination result is NO until the signal changes, and the determination operation is continuously performed. If a signal change occurs in any of the rotor position pulse signals Z _A , Z _B , and Z _C , the result of determination in step 72 is YE
S, and the control enters step 73, wherein to measure the signal time variation interval value t _n.

In step 74, the signal time change interval value t _n obtained in step 73 is used, and already described (2).
It is determined whether or not the inequalities expressed by the equations (3) are satisfied. If none of the inequalities is satisfied, it is determined that the deviation of the signal time change interval value t _{n from} the filtering value T _n−1 is small and within a predetermined range, and the determination result is NO. move on. That is, it is determined that the motor is not out of step.

In step 75, the filtering value T _n is calculated using the signal time change interval value t _n according to the equation (1), and the filtering value T obtained as a result is obtained.
The value of _n is filtered at step 76 by the filtered value T _n-1
Is set as This gives the filtering value T
The value of _n-1 is updated using the signal time change interval value t _n ,
Return to step 72.

Thus, the rotor position pulse signal Z
_A, Z _B, is measured the signal time variation interval value t _n whenever one signal change to occur among the Z _C, the value of the measured signal time variation interval value t _n is the filtering value T _n-1 Or not, ie, the filtering value T of the signal time change interval value t _n.
It is determined whether the deviation from _n-1 is within a predetermined range. DC brushless motor 1 for any reason
0 becomes unstable, and the determination result of step 74 is Y
When the state becomes ES, it is determined that the DC brushless motor 10 is out of step. In step 77, a stop signal TS is output, and the operation stop control of the DC brushless motor 10 is executed.

In the DC brushless motor driving device 20, as described above, the value of the filtering value T _{n-1 serving} as a reference for determining whether the value of the signal time change interval value t _n is normal or not is determined in the past. Measured signal time change interval value t
_{Since the} filtering processing result reflects _n−1 , t _n−2 ,..., the out-of-step discrimination is extremely independent of the instantaneous fluctuation of the signal time change interval value in the past. It can be performed stably and reliably. Especially, when the compressor is driven by a DC brushless motor, the rotation fluctuation is relatively large, so compare the filtering value reflecting the signal time change interval value measured in the past with the signal time change interval value at that time. According to the above-described configuration, the reliability of the determination of the step-out state is significantly improved as compared with the conventional configuration in which the immediately preceding signal time change interval value is compared with the current signal time change interval value. Further, since the filtering result represents the actual rotation speed value of the DC brushless motor 10, this can be used for the rotation speed control calculation.

[0023]

According to the present invention, the value of the filtering value serving as a reference for determining whether the value of the signal time change interval value is normal reflects the signal time change interval value measured in the past. Filtering processing result,
The step-out determination can be performed extremely stably and reliably without being largely influenced by the instantaneous fluctuation of the signal time change interval value in the past.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of an embodiment of a DC brushless motor driving device according to the present invention.

FIG. 2 is a waveform diagram of a set of rotor position pulse signals shown in FIG.

FIG. 3 is a flowchart showing a data processing program executed in an abnormal rotation determining unit in FIG. 1;

[Explanation of symbols]

10 DC brushless motor 11 to 13 drive winding 14 permanent magnet rotor 20 DC brushless motor driving device 40 energized switching unit 50 the position detecting circuit 60 abnormal-rotation judgment unit 61 measuring unit 62 filtering unit 63 abnormality determining means DT measurement time data t _n signal time variation interval value T _n filtered values TS stop signal Z _A to Z _C rotor position pulse signal

Claims (2)

[Claims] 1. A plurality of rotor position pulse signals indicating position information of a rotor are obtained based on a voltage induced in each drive winding of a DC brushless motor, and the rotor position pulse signal is applied to the drive windings. In a DC brushless motor driving method for performing commutation control of a drive current, a signal change time interval value between rotor position pulse signals is sequentially measured, and a signal change time interval value is filtered based on the measurement result. DC brushless motor characterized in that when the measured signal change time interval value exceeds a predetermined range determined based on the result of the filtering process, it is determined that the DC brushless motor is rotating abnormally. Drive method. 2. A position detecting means for outputting a plurality of rotor position pulse signals based on a voltage induced in each drive winding of a DC brushless motor; A DC brushless motor driving device comprising: an energization switching unit that performs commutation control of the driving current, wherein a signal change time interval value between the rotor position pulse signals in response to the output of the rotor position pulse signal is changed. A measuring means for sequentially measuring; a filtering means for filtering the signal change time interval value in response to the measuring means; a signal change time interval value obtained by the measuring means and a filtering result obtained by the filtering means And the signal change time interval value exceeds a predetermined range determined based on the filtering result. A direct current brushless motor driving device, comprising: an abnormality determination unit that outputs rotation abnormality determination information in a case where the motor is driven.