JP3248248B2 - Drive device for brushless DC motor - Google Patents

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 for detecting a relative position between a magnet rotor and an armature winding based on an induced voltage induced in an armature winding, and detecting the detected relative position. The present invention relates to a brushless DC motor driving device that drives a brushless DC motor based on the following.

[0002]

2. Description of the Related Art A brushless DC motor driving device is usually provided with a magnetic pole position detector for detecting a magnetic pole position of a rotor by detecting a magnetic field of the rotor. However, this magnetic pole position detector has drawbacks such as poor reliability in the compressor of an air conditioner used under high temperature and high pressure. Using the induced voltage detecting means for detecting the relative position between the magnet rotor and the armature winding by the position detecting means, based on the relative position detected by the position detecting means, Various proposals have been made in which the control means generates a commutation signal of the inverter, thereby eliminating the detector of the magnetic pole position of the rotor.

[0003] This type of brushless DC motor driving device supplies a commutation signal based on a synchronizing signal whose frequency gradually increases to the inverter at the time of start-up, so that the inverter gradually increases the frequency from the inverter to the armature winding. A voltage is applied to generate a rotating magnetic field having a gradually increasing rotation speed in the armature winding to start rotation of the magnet rotor.

When the rotation speed of the magnet rotor increases and reaches a predetermined rotation speed, a steady operation state (position detection operation state) utilizing the induced voltage is entered, and the position detection means detects the state. The control means generates a commutation signal of the inverter based on the relative position.

If the motor fails to start due to a load condition of the motor or some disturbance at the time of starting, and cannot enter a steady operation state, a commutation signal based on the synchronization signal is again sent from the control means. Is output. By starting at a timing when the load is reduced by repeating this start-up operation, a reliable start-up can be performed.

In the synchronous operation based on the synchronous signal, a stable operation can be performed with a sufficient torque if the voltage applied from the outside is large. However, if the load torque becomes large and the motor generated torque becomes insufficient, the speed fluctuation may occur. Large and very unstable operation. If the operation is switched to the position detection operation in this state, the operation fails and normal operation becomes impossible.

In particular, when the load is a compressor or the like, if there is a pressure difference between discharge and suction, the load torque increases, and the synchronous operation is started by the unstable operation as described above, and the operation is switched to the position detection operation. May fail.

In order to avoid the failure of switching due to the large load, the armature winding is driven by applying a voltage sufficient to stably start even at the maximum load torque assumed in advance.

However, in the above-described brushless DC motor drive device, when a torque equal to or greater than the assumed load torque is applied, the speed fluctuation becomes large even if the average speed is constant. Has a drawback in that the switching fails and an excessive current flows through the transistor included in the inverter, possibly damaging the transistor.

[0010] Recently, the present applicant has discovered the possibility of failure in switching from synchronous operation to position detection operation beforehand, and restarted the brushless brushless motor to prevent the transistor of the inverter from being damaged by the failure in switching. Driving device for DC motor was proposed (Japanese Patent Application No. Hei 4-0224).
No. 52).

FIG. 8 shows the configuration of a driving device for this brushless DC motor. In FIG. 8, reference numeral 71 denotes a DC voltage;
Is an inverter, 73 is a brushless DC motor, 74 is an armature winding, 75 is a magnet rotor, 76 is control means, and 77 is position detection means for detecting a relative position between the magnet rotor 75 and the armature winding 74. is there.

The control means 76 includes a synchronization signal generation means for outputting a synchronization signal, and determines whether or not the mode of the output signal from the position detection means 77 has a predetermined relationship with the mode of the synchronization signal. A mode determining means for determining is included.

The control means 76 receives the result of the discrimination by the mode discriminating means and changes the mode of the output signal from the position detecting means 77 to a normal state with respect to the mode of the synchronizing signal. As a state, after this normal state continues for a predetermined period, a drive signal for the inverter 72 is generated based on the output signal of the position detecting means 77.

That is, the control means 76 determines the timing of switching from the synchronous operation to the position detection operation based on the signal pattern relationship between the synchronization signal and the output signal from the position detection means 77. The above operation switching is not performed at the time of abnormal operation such as when the load torque is large, so that there is no switching failure and no damage to the transistor of the inverter 72.

[0015]

However, the drive device for the brushless DC motor described above sets a state in which the mode of the output signal of the position detecting means 77 does not have a predetermined relationship with the mode of the synchronous signal as an abnormal state. In this abnormal state, the voltage application from the inverter 72 to the armature winding 74 is stopped, the excitation of the armature winding 74 is stopped, and the armature voltage V and its frequency f are reduced to zero as shown in FIG. However, since the start operation is restarted from the beginning after the synchronous operation is stopped, there is a problem that the start time of the motor becomes extremely long when the abnormal state occurs.

Accordingly, an object of the present invention is to provide a method for synchronizing when a mode of a signal representing a relative position between an armature winding and a magnet rotor does not have a predetermined relationship with a mode of a synchronization signal. It is an object of the present invention to provide a brushless DC motor drive device capable of avoiding the stop of operation as much as possible and suppressing the extension of the motor start-up time.

[0017]

To achieve the above object, a brushless DC motor driving apparatus according to the present invention provides a brushless DC motor (3) for energizing and interrupting a current to a three-phase armature winding (4). An inverter (2) composed of a plurality of switching elements, a start command unit (61), and the start command unit
By the start command of (61), the synchronous signal generating means (62) for outputting a synchronous signal for synchronizing the switching operation of the inverter composed of the plurality of switching elements and the armature winding (4) are induced. Position detecting means (7) for detecting a relative position between the magnet rotor (5) and the armature winding (4) based on the induced voltage, and outputting a signal indicating the detected relative position; Drive signal generation means (64) for generating a drive signal for each of the plurality of switching elements based on a synchronization signal output from the generation means (62) or an output signal from the position detection means, Is a brushless DC motor drive device that performs a synchronous operation until it rotates at a constant speed, and then performs a position detection operation based on the induced voltage, wherein the synchronous signal and While the state of the drive signal generated based on the synchronization signal changes periodically, the state of the output signal of the position detecting means (7) corresponds to the change of the state of the synchronization signal and the state of the drive signal. Change periodically,
The state of the output signal of the position detecting means (7) has a predetermined specific relationship with the state of the synchronization signal corresponding to the state of the output signal or the state of the drive signal generated based on the synchronization signal. A determining unit (63) for determining whether or not the driving signal is output to the inverter (2) including the plurality of switching elements based on the synchronization signal output from the synchronization signal generating unit (62). At the same time, when the drive signal is output based on the synchronization signal, the determination means (63)
Receiving the determination result, the state of the output signal of the position detecting means (7) is a predetermined state which is in a predetermined relationship with the state of the synchronization signal or the drive signal generated based on the synchronization signal. After the continuation of the period, the position detecting means (7)
While the drive signal of each of the switching elements is generated based on the output signal of the above, the state of the output signal of the position detecting means (7) is the same as the state of the synchronous signal or the state of the drive signal generated based on the synchronous signal. If the predetermined specific relationship is not established, the state of the output signal of the position detecting means (7) is determined with respect to the state of the synchronization signal or the state of the drive signal generated based on the synchronization signal. An inverter (2) that increases the induced voltage generated in the armature winding stepwise by a predetermined value and stops the frequency increase of the induced voltage so as to have a specific relationship.
And a drive signal generating means (64) for generating a drive signal to the driver.

When a peak current of a predetermined value flows through the inverter (2), the peak current is detected,
Peak current detector that outputs a peak current detection signal (10)
And the drive signal generation means (64) includes a signal stop means for stopping the output of the drive signal to the inverter (2) when receiving the peak voltage detection signal from the peak current detector (10). It is desirable to have.

[0019]

When the start command means 61 issues a start command, the synchronous signal generating means 62 outputs a synchronous signal, and the drive signal generating means 64 generates a drive signal for the inverter 2 based on the synchronous signal. The brushless DC motor 3 is rotated by the driving signal, and an induced voltage is induced in the armature winding 4. Based on the induced voltage, the position detecting means 7 determines the relative position between the magnet rotor 5 and the armature winding 4. Is detected. Then, the determining means 63 determines whether or not the state of the output signal of the position detecting means 7 is in a predetermined relationship with the state of the synchronization signal (or the driving signal generated based on this synchronization signal). .

The drive signal generation means 64 receives the result of the determination by the determination means 63 and changes the state of the output signal of the position detection means 7 to the state of a synchronization signal (or a drive signal generated based on the synchronization signal). On the other hand, after a state having a predetermined specific relationship has continued for a predetermined period, the position detecting means 7
A drive signal for the inverter 2 is generated on the basis of the output signal.

On the other hand, the drive signal generating means 64 receives the result of the discrimination by the mode discriminating means 63,
If the state of the output signal is not in a predetermined relationship with the state of the synchronization signal (or the drive signal generated based on the synchronization signal), the output signal of the position detection The armature windings 4 are arranged so that the state is in a predetermined specific relationship with the state of the synchronization signal (or the drive signal generated based on the synchronization signal).
Is increased stepwise by a predetermined value, and a drive signal for stopping the frequency increase of the induced voltage is generated.

As described above, according to the present invention, for example, when the motor 3 is overloaded,
When the state of the output signal is abnormal with respect to the state of the synchronization signal, the induced voltage of the armature winding 4 is increased stepwise by a predetermined value. At the same time, a drive signal for stopping the increase in the frequency of the induced voltage is generated, the rotational driving force of the magnet rotor 5 is increased, and the state of the output signal of the position detecting means 7 is set in advance with respect to the state of the synchronization signal. Try to establish a specific relationship. Therefore, unlike the conventional brushless DC motor driving device that temporarily stops the synchronous operation when the above-described abnormal state occurs, it is possible to suppress the occurrence of the restart due to the start failure of the motor 3 and to reduce the startup time of the motor 3. Extension can be suppressed.

Further, when a peak current of a predetermined value flows through the inverter 2, a peak current detector 10 for detecting the peak current and outputting a peak current detection signal is provided. Is provided with a signal stopping means for stopping generation of a drive signal to the inverter 2 when receiving the peak voltage detection signal from the peak current detector 10. In this way, it is possible to prevent a current exceeding the peak current from flowing through the inverter 2 and prevent the inverter 2 from being damaged.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments.

FIG. 1 is a circuit diagram of one embodiment of the present invention.
In FIG. 1, 1 is a DC power supply, 2 is an inverter, 3 is a brushless DC motor, 4 is an armature winding, 5 is a magnet rotor, 6 is control means, 7 is position detection means, and 10 is a peak current detector. is there.

The inverter 2 includes six transistors Tr _{1 to} Tr ₆ and six diodes respectively connected in anti-parallel. The position detecting means 7 receives the induced voltages 8U, 8V, 8W of the armature winding 4 and receives the position detecting signals 9U, 9U.
V, 9W, and is composed of three filters 10U, 10V, 10W and three comparators 20U, 20V, 20W as shown in FIG. Each of the above filters 10U, 10V, 10W is, as shown in FIG.
Either a low-pass filter comprising a resistor 12 and a capacitor 13 and a DC removing circuit comprising a capacitor 14 and a resistor 15 connected thereto, or a DC removing circuit comprising a capacitor 16 and a resistor 17 as shown in FIG. Resistance 1
A low-pass filter composed of a capacitor 8 and a capacitor 19 is connected. In addition, the comparator 20U, 20V, 20W
Fig. 3 compares the outputs of the other two-phase filters.
Alternatively, it outputs the position detection signals 9U, 9V, 9W shown in FIG. The peak current detecting means 10 includes a comparator 101, and an inverting input terminal of the comparator 101
A reference voltage generation unit composed of resistors 102 and 103 connected in series to a power supply is connected, and a low-pass filter composed of a resistor 104 and a capacitor 105 is connected to a non-inverting input terminal of a comparator 101. The above comparator 1
01 is the drive signal generating means 64 of the control means 6
It is connected to the. The input side of the low-pass filter is connected to the cathode side of the DC power supply 1 via a resistor.

The peak current detecting means 10 detects the peak current when a predetermined value of the peak current flows through the inverter 2, and outputs a peak current detecting signal to the driving signal generating means 64.

The control means 6 includes a start command means 61, a synchronizing signal generating means 62, a mode discriminating means 63, and a driving signal generating means 64. The synchronization signal generating means 62 receives a start command signal from the start command means 61 and outputs a synchronization signal. Driving signal generating means 64 drive signals Tr ₁ to Tr as shown in FIG. 3 or 4 on the basis of the synchronization signal
₆ is generated and output. The drive signal causes the transistor of the inverter 2 to perform a switching operation, and the motor 3
Rotates. When the motor 3 rotates, induced voltages 8U, 8V, 8W are generated in the armature winding 4, and the position detecting means 7 receives the induced voltages and outputs position detection signals 9U, 9V, 9W. The mode discriminating means 63 compares the mode of the drive signal with the mode of the position detection signal after a certain period of time until the position detection signal is stabilized, and determines whether the mode of the position detection signal is predetermined with respect to the mode of the drive signal. It is determined whether or not there is a relationship. Here, the signal mode is a combination pattern of high and low of a signal at a certain point in time. Drive signals Tr ₁ to Tr ₆ and the position detection signal 9U, 9V, 9W
In each case, there are six combinations of high and low combinations of signals, and the patterns are represented by modes from 0 to 5.

In the normal operation state, the state where the mode of the position detection signal is in a fixed relation to the mode of the drive signal continues, and in the abnormal state where the voltage is insufficient due to the increase of the load torque, the abnormal Such a constant relationship does not continue.

In this embodiment, the mode determining means 63
Compares the mode of the mode and the position detection signal of the drive signal at the time of the rise of the pulse of the drive signal Tr ₁ to Tr _6,
As shown in FIG. 3, when a state in which the mode of the position detection signal is larger than the mode of the drive signal by 1 continues for a certain period of time or more, it is determined that the vehicle is in a normal operation state. On the other hand, when the mode of the position detection signal does not continue to be larger than the mode of the drive signal by one, that is, as shown in FIG. When the same state as the mode of the synchronization signal (a state where the phase is advanced from the state of FIG. 3) appears, it is determined that the state is the abnormal operation state.

FIG. 5 is a flowchart showing the operation of this embodiment. This flow is processed for each synchronization signal.

First, the mode discriminating means 6 determines in step S1
Thus, the position detection signals 9U, 9V,
The mode of 9 W is read, and in step S2, the mode of the position detection signal and the mode of the drive signal are compared to determine whether the mode of the position detection signal is one greater than the mode of the drive signal, and the state is increased by one. If there is, the process proceeds to step S3 to perform a normal process, that is, a process of generating a drive signal based on the synchronization signal and outputting the drive signal to the inverter 2, and when the state larger by one has continued for a predetermined time, switches to the position detection operation.

On the other hand, if the mode of the position detection signal is not larger than the mode of the drive signal by one in step S2, the process proceeds to step S4, where the drive signal generation means 6
4 outputs a drive signal to the inverter 2 to stop the increase in the frequency f 2 of the induced voltage V, as shown in FIG. Then, proceeding to step S5, as shown in FIG. 6, a drive signal for increasing the induced voltage V of the armature winding 4 in a stepwise manner is output to the inverter 2.

Next, proceeding to step S6, it is determined whether or not the peak current detecting means 10 has output a peak current detecting signal, and it is determined that the peak current detecting means 10 has output a peak current detecting signal. At step S7, the process ends when the peak current detection means 10 determines that the peak current detection signal has not been output, and the process is restarted from the beginning of this flow according to the next synchronization signal.

In step S7, the drive signal generation means 64 stops outputting the synchronization signal to the inverter 2 and stops the synchronous operation. Steps S6 and S7 constitute signal stopping means. Then, after the synchronous operation is stopped, the process proceeds to step S8, and the stop count counted by a stop counter (not shown) is increased by one. Next, proceeding to step S9, it is determined whether or not the stop count number has exceeded a predetermined number. When it is determined that the stop count number has exceeded the predetermined number, step S9 is performed.
When the process proceeds to step S13 and it is determined that the stop count has not exceeded the predetermined number, the process proceeds to step S10.

In step S13, it is determined that the motor 3 should not be restarted, and the start of the motor 3 is stopped.

On the other hand, in step S10, a stop timer
(Not shown), and when the stop timer counts a predetermined stop time, the flow proceeds from step S11 to step S12.
Then, preparation for starting is performed by restart processing based on the synchronization signal, and processing is performed again from the beginning of this flow.

As described above, according to this embodiment, for example,
If an abnormal state occurs in which the mode of the output signal of the position detecting means 7 does not have a predetermined relationship with the mode of the synchronization signal due to an excessive load applied to the motor 3 or the like, the armature winding 4
Of the induced voltage V is increased stepwise by a predetermined value, and a drive signal for stopping the increase of the frequency of the induced voltage V is generated. 7 so that the mode of the output signal is in a predetermined relationship (normal state) with the mode of the synchronization signal.

Therefore, unlike the conventional brushless DC motor driving device which temporarily stops the synchronous operation when the above-mentioned abnormal condition occurs, the occurrence of restart due to a poor start of the motor 3 can be suppressed. Extension of startup time can be suppressed.

When a predetermined value of the peak current flows through the inverter 2 due to the increase of the induced voltage V, the peak current detecting means 10 detects the peak current and outputs a peak current detection signal. When the motor 3 starts, the drive signal generating means 64 stops generating the drive signal to the inverter 2 and stops the synchronous operation when receiving the peak voltage detection signal. It can prevent the current exceeding the peak current from flowing,
The damage of the inverter 2 can be prevented.

In the above embodiment, when the mode of the position detection signal is larger than the mode of the drive signal by one for a certain period of time, the operation based on the synchronization signal is switched to the operation based on the position detection signal. However, depending on the circuit configuration of the position detection means 7 and the method of determining the mode of the position detection signal, the mode of the position detection signal has another relationship with the mode of the drive signal, for example, the case where the mode is in the same mode is the normal operation state. In such a case, it is preferable to switch the operation based on the synchronization signal to the operation based on the position detection signal when the state of such a relationship continues for a certain period.

In the above embodiment, the mode of the position detection signal is compared with the mode of the drive signal which has a one-to-one correspondence with the mode of the synchronization signal. However, the mode of the synchronization signal is compared with the mode of the synchronization signal itself. You may do so.

Further, in the above embodiment, the mode of the position detection signal is read at the start timing of the mode of the synchronization signal, and the two are compared. However, the mode of the synchronization signal is read at the start timing of the mode of the position detection signal, and both are read. You may make it compare.

[0044]

As is apparent from the above description, in the brushless DC motor driving apparatus according to the present invention, it is determined whether or not the state of the output signal of the position detecting means has a predetermined specific relationship with the state of the synchronization signal. A drive signal generation means for generating a drive signal for an inverter for energizing and interrupting the current to the three-phase armature winding of the brushless DC motor, receiving the determination result of the determination means, If the state of the output signal of the detecting means is not in a predetermined specific relationship with respect to the state of the synchronization signal, the state of the output signal of the position detecting means is predetermined with respect to the state of the synchronization signal. A drive signal is generated such that the induced voltage of the armature winding is increased stepwise by a predetermined value so as to have a specific relationship, and the frequency of the induced voltage is stopped from increasing.

As described above, according to the present invention, the state of the output signal of the position detecting means changes with respect to the state of the synchronizing signal in a predetermined relationship with the state of the synchronizing signal, for example, when an excessive load is applied to the motor. When an abnormal state occurs, the induced voltage of the armature winding is increased stepwise by a predetermined value, and a drive signal for stopping the frequency increase of the induced voltage is generated. The rotational driving force of the child is increased so that the state of the output signal of the position detecting means has a predetermined specific relationship (normal state) with respect to the state of the synchronization signal. Therefore, unlike the conventional brushless DC motor drive device that temporarily stops synchronous operation when the above-mentioned abnormal state occurs, it is possible to suppress the occurrence of restart due to poor motor start-up and extend the motor start-up time. Can be suppressed.

Further, when a peak current of a predetermined value flows through the inverter, a peak current detector for detecting the peak current and outputting a peak current detection signal is provided. When a signal stopping means for stopping generation of a drive signal to the inverter when receiving a peak voltage detection signal from the peak current detector is provided, when the motor is started, a current exceeding the peak current is supplied to the inverter. Can be prevented from flowing and damage to the inverter can be prevented.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a position detection unit and a circuit diagram of a filter according to the embodiment.

FIG. 3 is a diagram showing a relationship between a drive signal and a position detection signal during normal operation in the embodiment.

FIG. 4 is a diagram showing a relationship between a drive signal and a position detection signal during abnormal operation in the embodiment.

FIG. 5 is a flowchart showing the operation of the embodiment.

FIG. 6 is a diagram showing a state in which the induced voltage of the armature winding is increased stepwise during the abnormal operation in the embodiment.

FIG. 7 is a diagram showing a state in which an induced voltage of an armature winding is set to zero during abnormal operation in a conventional example.

FIG. 8 is a block diagram of the conventional example.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 DC power supply 2 inverter 3 brushless DC motor 4 armature winding 5 magnet rotor 6 control means 7 position detection means 10 peak current detection means 6
1. Start command means, 62: Synchronous signal generating means, 63: Mode discriminating means, 64: Drive signal generating means.

Continuation of the front page (56) References JP-A-61-135384 (JP, A) JP-A-62-268386 (JP, A) JP-A-3-203589 (JP, A) JP-A-3-235695 (JP, A) JP-A-4-1601091 (JP, A) JP-A-4-304190 (JP, A) JP-A-4-304193 (JP, A) JP-A-5-219784 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02P 6/00

Claims (2)

(57) [Claims] An inverter (2) comprising a plurality of switching elements for energizing and interrupting a current to a three-phase armature winding (4) of a brushless DC motor (3); a start command means (61); A synchronous signal generating means (62) for outputting a synchronous signal for synchronizing the switching operation of the inverter composed of the plurality of switching elements according to a start instruction of the start instruction means (61); Position detecting means (7) for detecting a relative position between the magnet rotor (5) and the armature winding (4) based on the induced voltage and outputting a signal representing the detected relative position; A drive signal generation unit (64) for generating a drive signal for each of the plurality of switching elements based on the synchronization signal output by the synchronization signal generation unit (62) or the output signal of the position detection unit; Sometimes on A brushless DC motor driving device that performs a synchronous operation until the motor rotates at a constant speed, and thereafter performs a position detection operation based on an induced voltage, based on the synchronization signal and the synchronization signal. The state of the drive signal thus generated periodically changes, while the state of the output signal of the position detecting means (7) periodically changes in accordance with the change in the state of the synchronization signal and the state of the drive signal. The state of the output signal of the position detecting means (7) has a predetermined relationship with a state of a synchronization signal corresponding to the state of the output signal or a state of a drive signal generated based on the synchronization signal. An inverter comprising a plurality of switching elements based on a synchronization signal output from the synchronization signal generating means (62).
In addition to generating the drive signal to (2), receiving the determination result of the determination means (63) at the time of output of the drive signal based on the synchronization signal, the state of the output signal of the position detection means (7) becomes the synchronization signal or the synchronization After the state of the predetermined specific relationship with the state of the drive signal generated based on the signal has continued for a predetermined period, based on the output signal of the position detection means (7), When the drive signal is generated, and the state of the output signal of the position detecting means (7) is not in the above-described predetermined relationship with the state of the synchronization signal or the state of the drive signal generated based on the synchronization signal. The electric machine may be configured such that the state of the output signal of the position detecting means (7) has the above-described predetermined relationship with the state of the synchronization signal or the state of the drive signal generated based on the synchronization signal. Child roll And a drive signal generating means (64) for generating a drive signal to the inverter (2) so as to increase the induced voltage generated in the inverter stepwise by a predetermined value and to stop the frequency increase of the induced voltage. A driving device for a brushless DC motor, characterized in that: And a peak current detector (10) for detecting a peak current when a peak current of a predetermined value flows through the inverter (2) and outputting a peak current detection signal. The signal generating means (64) includes the peak current detector
2. The brushless DC motor drive device according to claim 1, further comprising signal stop means for stopping output of a drive signal to the inverter (2) when receiving the peak voltage detection signal from (10). .