JPH0449890A - Lock alarm device of brushless motor - Google Patents

Abstract

PURPOSE:To make it easy to process an output signal by using a flip-flop circuit and an output transistor instead of a lock alarm circuit. CONSTITUTION:Normally, a transistor 36 is turned off with a transistor 32 by a pulse transmitted from a rotation pulse circuit 5 and an output transistor 39 transmits level 'L'. When a rotor is locked at this time, the rotation pulse circuit stops transmitting the rotation pulse and the potential of a capacitor 22 heightens. When the potential heightens to point A, a lock detection circuit 7 is operated to turn a transistor 37 on. Therefore, flip-flop inverts, the transistor 36 is turned on, and the output transistor 39 transmits level 'H'. Even if the potential of the capacitor 22 lowers to point C and the level of the output of the lock detection circuit 7 becomes 'L', the flip-flop circuit does not invert and continues to transmit level 'H'.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lock alarm device for a brushless motor, and more particularly to a device that issues an alarm to the outside when the motor stops rotating for some reason.

Conventional technology In recent years, small DC motors have been used not only in the acoustic field, but also in information and
Its excellent controllability has also been recognized in the industrial field, and its applications are rapidly expanding.

Among these, brushless motors have no contact parts such as brushes and commutators, and have the advantage of long life, so their use as industrial motors where reliability is particularly important is expanding.

Under these circumstances, the drive method of small axial fans has been switched from alternating current to direct current in recent years, and the number of direct current axial fans using brushless motors is increasing.

As the packaging density of industrial equipment such as computer-related equipment increases, direct current axial fans become necessary for cooling the equipment, and their reliability is also required to be high. In other words, if the motor stops for some reason, it not only prevents the motor coil from burning out, but also sends a warning to the device itself to prevent accidents.
It has become necessary to automatically return to normal rotation when the cause is removed.

In FIG. 3, a magnetic detection circuit 11 a position signal amplification circuit 2
．． Output circuit 3. The coil 4 constitutes a fan drive motor. In this case, if the motor stops due to external factors or is operated at low speed under overload, the coil 4 will be burnt out due to excessive current and the motor will no longer function.

In order to solve these problems, the following circuit configuration is used to cut off the output circuit 3 and prevent excessive current from flowing. In other words, 5 constitutes a differential amplifier with a resistor 12 as a load. Transistors 15 and 1 constitute a differential amplifier whose active loads are transistors 10 and 11 and transistors 17 and 18 which constitute a current mirror circuit.
6 and transistors 13 and 19 that share a collector that receives signals from the resistor 12 and transistor 18, and generates a pulse output from the common collector in synchronization with the rotational position of the rotor.

Reference numeral 6 denotes a flip circuit which receives signals from the inversion detection transistor 25 and the inverter 29, and connects the capacitor 22 for storing charge to a constant current source 23 to put it in a charged state, or connects it to a constant current source 24 to put it in a discharged state. It is a flop circuit. 7 is a lock detection circuit composed of resistors 26 and 27 that determine hysteresis, a comparator 28, and the above two inverters. When the rotor is locked and the potential of the capacitor 22 rises to point A in FIG. 2(a), The lock protection transistor 30 is driven to cut off the output circuit 3, and when the voltage drops to zero point, an output is made to energize the output circuit 3. During normal operation, the discharge transistor 21 is connected to the capacitor 22 by the pulse output from the rotation pulse circuit 5.
discharge the electric charge. Reference numeral 41 denotes a lock warning transistor which receives a signal from the lock detection circuit and outputs an H level signal when locked. 9, 14, and 20 are constant current sources.

The operation at this time will be explained using FIG. 2.

In FIG. 2, (a) shows the charging and discharging states of the capacitor 22, which is T in steady state.

Since a rotation pulse signal is output periodically at intervals, the potential of the capacitor 22 is the potential VOFF which cuts off the output circuit 3.
will not be reached. Therefore, the motor continues to rotate without stopping. On the other hand, if the motor is stopped due to an external factor, the potential of the capacitor 22 continues to rise and reaches point A.

When the point A is reached, the lock detection circuit 7 operates and cuts off the output circuit 3 via the lock protection transistor 30. The potential further rises to point B, that is, V H-V
When ref I + V BE is reached, the inversion detection transistor 25 operates to switch the contact of the flip-flop circuit 6 to the constant current source 24 side, causing the capacitor 22 to be discharged. Therefore, the potential continues to fall and reaches the zero point. Then, the lock detection circuit 7 operates,
At the same time, the output circuit 3 is energized via the lock protection transistor 30 and the flip-flop circuit 6 is activated.
switch the contact to the constant current source 23 side. The potential of the capacitor 22 continues to rise again, and when it reaches point D, the same operation as at point A occurs. During this time T3. The motor repeats 0FF10N at intervals of T4 until the external factor is removed. When the external factor is removed in the interval T4, the motor is energized and generates rotation pulses. This pulse causes the discharge transistor 21 to operate and the capacitor 22 to
is discharged and returns to steady state.

(b) shows the operation of the lock alarm circuit 41 corresponding to (a). In this case, while the rotor is locked and the lock protection circuit 30 is cutting off the output circuit 3, the alarm circuit 41 outputs the "H" level, and conversely, when the lock protection circuit is released, the output of the alarm circuit 41 is becomes “L” level.

Problems to be Solved by the Invention As explained in FIG. 2(b'), the lock protection circuit 3
0 outputs an "H" level signal when it is operating, but the T4 period in which the restart pulse is generated is at the "L" level, making it difficult to process this output signal.

To solve this problem, the present invention is designed to prevent the rotor from locking, and once the lock protection circuit is activated, the signal remains at only the "H" (or "L") level until the cause is removed and a circuit pulse is generated. The purpose of this is to facilitate the processing of the output signal by configuring it so that it outputs.

Means for Solving the Problems In the present invention, the lock alarm circuit 41 is replaced by a flip-flop circuit and an output transistor.

Operation With this configuration, once the rotor is locked and receives a signal from the lock detection circuit, it will maintain this state until it receives the next signal from the rotation pulse circuit, and will not be affected by the restart pulse.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

Figure 1 shows the circuit configuration of the magnetic detection circuit 11.
Position signal amplification circuit 2. Output circuit 3. The coil 4 constitutes a fan drive motor, and the rotation pulse circuit 5, flip-flop circuit 6, and lock detection circuit 7 have the same configuration as the conventional example, and a detailed explanation will be given for the same operation as described above. Omitted.

8 is a resistor 34 and 3 forming a flip-flop circuit.
5. A lock alarm circuit composed of transistors 32, 33, 36, and 37 and an output transistor 39, which receives signals from the lock detection circuit 7 and rotation pulse circuit 5;
It is output from the transistor 39. 9,14.20.
31 and 38 are constant current sources.

FIG. 2(C) shows the operation of the lock alarm circuit 8. During normal operation, the transistor 36 is turned off by the transistor 32 by the pulse output from the rotation pulse circuit 5.
The output transistor 39 then outputs the "L" level.

At this time, when the rotor is locked, the rotation pulse circuit stops outputting rotation pulses, and the potential of the capacitor 22 increases.

When the voltage rises to point A, the lock detection circuit 7 operates and turns on the transistor 37. Therefore, the flip-flop is inverted, the transistor 36 is turned on, and the output transistor 3 is turned on.
9 outputs "H" level.

Even if the potential of the capacitor 22 drops to the 0 point and the output of the lock detection circuit 7 goes to the "L" level, the flip-flop circuit is not inverted and continues to output the "H" level. Next, when the external factor is removed and the rotation pulse circuit is activated, the flip-flop circuit is inverted again by this pulse output and returns to its original state, causing the output transistor 39 to go to the "L" level.

Effects of the Invention As detailed above, according to the present invention, the special alarm output when the rotor is locked becomes only the "H" (or "L") level output, which facilitates subsequent circuit processing and reduces the number of parts. The effects of reduction are significant.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of an embodiment according to the present invention, FIG. 2 is an operation explanatory diagram, and FIG. 3 is a circuit configuration diagram of a conventional example. 1... Magnetic detection circuit, 2... Position signal amplification circuit, 3... Output circuit, 4... Coil, 5... Rotating pulse circuit, 6...
Flip-flop circuit, 7...Lock detection circuit, 8...Lock alarm circuit, 21...
Discharge transistor, 22... Capacitor for storing charge, 25... Reversal detection transistor. Name of agent Patent attorney Shigetaka Awano

Claims (1)

[Claims] A constant current source, a capacitor 22 that stores electric charge, a rotating pulse circuit 5 that generates pulses in synchronization with the rotational position of the rotor, and a discharge device that discharges the electric charge of the capacitor 22 by the output pulse of the rotating pulse circuit during normal operation. a flip-flop circuit 6 that maintains the charging state and the discharging state of the capacitor 22; an inversion detection transistor 25 that detects the timing of transition of the capacitor 22 from the charging state to the discharging state; A lock detection circuit 7 with hysteresis that cuts off the output circuit when the voltage rises to a predetermined first potential and energizes the output circuit when the voltage drops to a predetermined second potential; “H” when locked by signal
(or "L") level signal. A lock alarm circuit 8 for a brushless motor.