JPS61189187A - Protecting device of motor - Google Patents

Abstract

PURPOSE:To detect the rotation of a motor without using a capacitor by feeding back a kickback pulse by a Zener diode, and delaying the falls of the first and second pulse trains. CONSTITUTION:Currents are flowed by the first and second output circuits 8, 11 to the first and second drive coils 1, 2 of a motor in response to the position of a rotor detected by a Hall IC 3 to control to drive the motor. In this case, an AND gate 16 connected with the input terminals of the circuit 8, 11, an inverting transistor 17, a capacitor 18, and a stopper 20 for stopping the operation of a waveform shaper 4 are provided to construct a protecting device, and Zener diodes 14, 15 are provided in the circuits 8, 11 to feedback a kickback pulse. The falls of the pulse trains are delayed by the feedback of the kickback pulse, and a stop signal is generated from the stopper 20 through the gate 16 at motor lock time. This is input to the shaper 4 to perform the protection against the damage.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a motor protection device for preventing brushless DC motors from being destroyed.
The purpose of this invention is to provide a motor protection device suitable for use in integrated circuits.

(b) Conventional technology: Brushless DC motors are currently widely used because they have a long life even when rotated at high speeds. The brushless motor is
The rotor is rotated by detecting the position of the rotor and supplying current to a plurality of drive coils according to the position of the rotor. The current supplied to the drive coil is set to a large value.

Therefore, if the motor locks for a long time or continues to rotate at abnormally low speed due to overload, the drive coil will generate heat and burn out.

JP-A-58-15438 discloses a technology for immediately stopping motor drive to prevent damage when a motor lock occurs.
It is described in Publication No. 5. According to the above-mentioned publication, a pulse of a predetermined period is generated by detecting the back electromotive force of the drive coil, and the rotation of the motor is detected by discharging a capacitor constituting the time measuring means using the pulse. .

Therefore, in the case of the above-mentioned publication, when the motor lock occurs, the counter electromotive force is no longer generated, and the pulse is no longer generated, the terminal voltage of the capacitor becomes equal to or higher than the n constant level.
It is possible to detect that a motor lock has occurred.

(c) Problems that the invention seeks to solveHowever,
As disclosed in the above-mentioned publication, the method for detecting back electromotive force requires detecting the voltage across the drive coil, one end of which is connected to a power source, and therefore the entire detection circuit must be connected to a high voltage power source.

Therefore, the circuit disclosed in the above-mentioned publication had to be constructed entirely of high-voltage elements, and had the disadvantage that it was difficult to integrate it into an IC when the power supply voltage was high. Additionally, since the power supply voltage is applied to the entire circuit, it also has the disadvantage of being vulnerable to surge voltages.

B) Means for Solving the Problems The present invention has been made in view of the above-mentioned points, and includes a connection between the input and output of the first and second output circuits for supplying power to the first and second drive coils. a Zener diode for feeding back the kick pack pulse generated by the drive coil; an AND gate for ANDing the signals obtained at the input terminals of the first and second output circuits; The present invention is characterized in that it includes a capacitor whose discharge is controlled, and a stop means that stops power supply to the first and second drive coils in accordance with the terminal voltage of the capacitor.

(E) Function According to the present invention, the pulse width of the output signal of the AND gate can be increased, and sufficient discharge of the cone capacitor can be performed. As a result, the capacitance of the capacitor can be reduced, the value of the charging resistor can be made small, and an adverse effect on the bias current supplied to the IC can be prevented.

(v) Embodiment FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which (1) shows the first drive coil, (2) shows the second drive coil, and (3) shows the first and second drive coils. A Hall IC (an IC that combines a Hall element and a comparator 4) is used to detect the position of the rotor driven by drive coils (1) and (2), and (4) shapes the waveform of the output signal of the Hall IC. waveform shaping circuit,
(5) includes the first and second transistors (6) whose emitters are commonly connected and the waveform shaping circuit (4);
A differential amplifier circuit (6) generates a first pulse train having the same phase as the output signal and a second pulse train having the opposite phase to the output signal according to the output signal of the output signal. comprising third and fourth transistors (9) and (10) whose emitter paths are cascaded, amplifying a first pulse train obtained at the collector of said first transistor (6) and driving a corresponding current into a first drive; The first output circuit, which supplies the coil (1), has fifth and sixth transistors (12
1 and (131), a second output circuit (14) amplifies the second pulse train obtained at the collector of the second transistor (7) and supplies a corresponding current to the second drive coil (2); A first Zener diode whose cathode is connected to the output terminal of the first output circuit (6) and whose anode is connected to the input terminal of the first output circuit (8); At the output end, second Zener diodes whose anodes are connected to the input ends of the second output circuit Ml; Q7) is an inverting transistor that inverts the output signal of the antagonist connected to the end of the antagonal
+vcc2) via the charging resistor α1 and discharged by the inverting transistor αη;
and (20 is a stop circuit that compares the terminal voltage of the capacitor Oal with a reference voltage (Vref) and generates a stop signal to stop the operation of the waveform shaping circuit (4) when the terminal voltage becomes a dog. It is.

When the motor is rotating, a signal that periodically changes to rHJ and rLJ is generated from the Hall IC (3), and after this signal is converted into a rectangular wave by the waveform shaping circuit (4), it is sent to the differential amplifier circuit. (g) is applied. Therefore, the differential amplifier circuit (5
) is connected to the corefter of the first transistor (6).
The first pulse train shown in Figure (a) is generated, the second pulse train shown in Figure 2 (c) is generated at the collector of the second transistor (7), and the first pulse train is applied to the first dj output circuit (6). , the second pulse train is applied to the second output circuit 11), and the operating current is supplied to the first and second drive coils (1) and (2) by the first and second output circuits ((8) and Therefore, the output voltage of the first output circuit (5) has a waveform as shown in FIG. Similarly, the output voltage of the second output circuit 0 has a waveform as shown in FIG.

Since the first and second Zener diodes 04) and (15+) are connected between the input and output terminals of the first and second output circuits (6) and the side, respectively, the kick pack that exceeds the Zener voltage V2 The pulses are fed back to the first and second output circuits (6) and the input terminals of U, and the voltage at the input terminal of the first output circuit (6) is as shown in FIG. The voltage at the input of the circuit is the second
It will look like the figure below. In FIG. 2, range A is the voltage corresponding to the kick pack pulse, and range B is the voltage corresponding to the back electromotive force. Furthermore, in FIG. 2, the first and second pulse trains indicated by (a) and (b) have sufficiently long pulse widths compared to the ranges A and B, so that
Some parts are omitted from the drawing.

The signals shown in FIG. A signal as shown in FIG. 2 (g) is generated at the output terminal of the . and,
The output signal of the AND gate 06) is the output signal of the inverting transistor α'? ), an inverted signal of the signal shown in FIG. 2(G) is generated at the collector of the inverted transistor surface. When the collector of the inverting transistor (17) becomes "L", the capacitor is discharged, and when it becomes "H", it is charged by the power supply voltage (10Vcc2) via the charging resistor. In that case, the charging time constant is determined according to the values of the capacitor (181) and the charging resistor JA=H, and the discharging time is determined by the pulse width of the output signal of the Antoge [16]. Therefore, the terminal voltage of the capacitor (+8) becomes as shown in FIG. 2(a). The output pulse of AND gate 00 is generated every time the first and second pulse trains fall, and each time the capacitor (1) is discharged, the terminal voltage of the capacitor O→ will never exceed a predetermined level. do not have.

The terminal voltage of the capacitor 0 is applied to a stop circuit (20).The stop circuit (20 is connected to a resistor (2I) and
The reference voltage Vref created by the second function is compared with the terminal voltage of the capacitor QS, and when the terminal voltage is negative, a stop signal is generated.As mentioned above, a pulse signal of a predetermined period is generated from the AND gate As long as continues to occur, the stop signal will not be generated.

If a motor lock occurs and pulses are no longer generated from the Hall IC (31), the output signal of the differential amplifier circuit (G) will no longer change, and one output will be "■I" and the other output will be r.
It will remain LJ. Then, the output circuit on the side that has become rHJ continues to operate, and current continues to flow through the corresponding drive coil, creating a risk of destruction. When the output signal of the differential amplifier circuit (5) ceases to change, the output pulse of the analog gate (16) also ceases to be generated, so that the capacitor 0 is not discharged and its terminal voltage increases. When the terminal voltage exceeds the reference voltage Vref, a stop signal is generated from the stop circuit (20) and applied to the waveform shaping circuit (4). Both become rLJ and destruction protection is achieved.
The stop circuit (20 stop signals) is applied to, for example, the constant current source (c) of the differential amplifier circuit (5) so that the power supply to the first and second drive coils (1) and (2) is stopped at the same time. (G) Effects of the Invention As described above, according to the present invention, the kick pack pulse is fed back by the Zener diode to measure the delay in the fall of the first and second pulse trains. , it is possible to detect the rotation of the motor without using a capacitor that is difficult to integrate into an IC.Furthermore, according to the present invention, the rotation is detected by connecting an AND gate to the input terminal of the output circuit. Therefore, the entire detection circuit can be operated with a low power supply voltage, which has the advantage of allowing the use of elements with low withstand voltage.Furthermore, the capacitor can be discharged for a period approximately equal to the width of the kick pack pulse. Therefore, a capacitor with a large capacity can be used, and the value of the charging resistance can be made small.Incidentally, if the embodiment is used, a discharge time of 200 to 300 .mu.sec can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIGS. 2(a) to 2(g) are characteristic diagrams showing waveforms of various parts in FIG. 1. Explanation of main drawing numbers (1)...First drive coil, (2)...Second drive coil, (2)...Differential amplifier circuit, (6)...First drive coil
Output circuit, 0...second output circuit, αa...first
Zener diode, Q! 19...Second Zener diode, 06)...And gate, On...Capacitor, (To)...Stop circuit. Applicant Sanyo Electric Co., Ltd. and 1 other agent Patent attorney Shizuka Sano

Claims (1)

[Claims] (1) first and second drive coils, and position detection means for detecting the positions of the rotor driven by the drive coils;
a pulse generating circuit that generates first and second pulse trains having opposite phases to each other in accordance with the output signal of the position detecting means;
In the motor, the motor includes a first output circuit that supplies an operating current to the first drive coil according to the pulse train, and a second output circuit that supplies an operating current to the second drive coil according to the second pulse train. A Zener diode inserted between the input and output of the first and second output circuits, an AND gate that ANDs the signals obtained at the input terminals of the first and second output circuits, and a a capacitor whose charging and discharging are controlled by the capacitor, and a stopping means for stopping power supply to the first and second drive coils according to the terminal voltage of the capacitor, and when the motor is locked, the stopping means is activated to stop the motor. A motor protection device characterized in that it protects the motor.