JPS61218393A - Motor drive circuit - Google Patents

Abstract

PURPOSE:To readily detect the presence or absence of the rotation of a motor with the terminal voltage of a capacitor by charging a capacitor at phase switching time, discharging the capacitor at motor rotating time to hold the terminal voltage of the capacitor constant. CONSTITUTION:A Hall element 1 detects the rotating position of a motor, the detection output is amplified by an amplifier 11, ad then supplied to output circuits 12, 13. A motor coil L1 is energized by the output circuits 12, 13. A capacitor C41 in a motor stop detector 14 is charged at phase switching time of the fine time width when energizing the coil L1, and discharged at the motor rotating time. The terminal voltage of the capacitor C41 hold substantially constant voltage level while the motor rotates as prescribed, and drops when the motor is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a motor drive circuit, and particularly to a circuit technique suitable for use in detecting whether or not a motor is rotating.

[Background technology]

Motors are used in various electronic devices.

An example of a motor drive circuit is provided by Motor Drive Electronics (February 20, 1981, 1st edition, 1st printing, 9th edition, Ohmsha Co., Ltd. P, 50-P).

53) etc. For example, in a fan motor for heat dissipation in an electronic device, even if the motor stops due to an unexpected situation, it may not be noticed. In this case, the temperature inside the electronic device increases rapidly, making it impossible for the electronic circuit to operate normally, leading to malfunction or, in extreme cases, failure.

Therefore, the above-mentioned stoppage of the motor is detected.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a motor drive circuit that is capable of reliably detecting the stoppage of rotation of a motor by comparing a reference voltage with an output voltage that energizes a motor coil.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief summary of the invention disclosed in this application is as follows:
It is as follows.

In other words, a three-differential circuit is provided to compare the reference voltage with the output voltages of multiple output circuits, and the capacitor is charged when the phase is changed over a small time width, and the capacitor is discharged when the motor rotates. Accordingly, the object of the present invention, which is to reliably detect whether or not the motor is rotating, is achieved by maintaining the terminal voltage of the capacitor at a predetermined level when the motor is rotating.

〔Example〕

Next, an embodiment of a motor drive circuit to which the present invention is applied will be described with reference to FIGS. 1 to 3. The motor drive circuit shown in FIG. 1 is constituted by a semiconductor integrated circuit (hereinafter referred to as IC), and the circles surrounding the numbers are external connection terminals.

The feature of this embodiment is that it detects all stops of rotation of the motor and obtains a detection signal to notify this.

The Hall element 1 shown in FIG. 1 is used to detect the rotational position of the motor, and its output signal VA changes as shown in FIG. --Q! supplied to each base.

The circuit block 11 constitutes an amplifier circuit, and includes a transistor Q.
, -Qt is the first stage amplifier, transistors Qe, Q, ,
Q? , Q constitute a high-gain amplifier, and the output voltage VB, c obtained from the transistors Qy-Qa has a waveform with extremely sharp rises and falls, as shown in Figure 2 @ (C1). Transistor Q4 t Q
o * Q+o + Q++ * Q+t o Resistor R4+ R4* R6+ R6 as constant current circuit CS,
Each constitutes a constant current circuit.

Now, suppose that the base of the transistor Q1 becomes a high level, and the base of the transistor Q becomes a low level.As a result of the voltage drop across the resistor R1, the base of the transistor Q becomes a low level and the base of the transistor Q6 becomes a high level. As a result, transistor Q constitutes a current filter circuit.

The output current of is small, and the current is the transistor Q, o
2, the output voltage c becomes low level as shown in FIG. 20. At this time, since the voltage level of the output voltage VC is lower than the voltage Vx supplied to the base of the transistor Qllll IQ112, the emitter voltage of the transistor Qa+ is lowered through the resistor Rszk, and the transistor Qs+ is turned on. works,
Transistor Qsa is turned off.

On the other hand, transistor Q8 constituting the current mirror circuit
The output current of is dog and oak, and part of it is transistor Q + t.
Although the voltage is sunk by V n FiJ 2
The level becomes high as shown in FIG. At this time, the output voltage V
The voltage level of B is transistor Qzt' u Qz
Since the voltage x supplied to the base of □ is also at a high level, the emitter voltage of transistor Q2□ is fully pushed up through resistor R□, transistor Qtt is turned on, and transistor Q□ is turned on. becomes.

Next, the two output circuits 12 and 13 operate, and first the circuit operation of the output circuit 12 will be described.

Transistor Q! , by turning off, the 7-disaster Q*a! Q! 4. All Q211 are turned off,
These circuit operations can be ignored.

However, transistor Q! t turns on, transistors Qga t Qty operate in an on state, and transistors Q6 . Through the transistor Q! A base current is supplied to 8. Therefore, if transistor Q□ is not on, transistor Qto? Drive to ON state.

On the other hand, regarding the output circuit 13, the transistor Qs
By operating r in the on state, transistor Qa
The base voltage of s is pulled down, turning it on. Therefore, the base voltage of transistor Qan also decreases,
This operates in the on state and resistor R8! ,,) transistor Q84. A base current is supplied to the transistor Qss via the resistor Ra5ffi. Then, the transistor Qss operates in an on state.

On the other hand, since the transistor Qsz is off, the transistors Qsa, Qsy p Qsa? Qa
. When both are off, these circuit operations can be ignored.

That is, between T1 shown in FIG. 2, transistors Q□, Q3 . operates in the on state, ten Vc
c From the power supply to resistor R2B* F transistor Q35.
Motor coil L1. A current I flows through the transistor Q2° and the ground line.

On the other hand, between 12 and 12, the phases of the seven detection signals obtained from Hall element 1 are reversed, so transistor Q+
The base voltage of transistor Q2 becomes low level, and the base voltage of transistor Q2 becomes high level. And the base voltage of transistor Q is at the 71 level.

Since the base voltage of the transistor Qa becomes low level, the output voltage VB e vc is inverted as shown in FIG. 2 (C1) by the circuit operation of the transistors Q, -Q.

As a result, regarding the output circuit 12, the transistor Qht is turned on9, and the transistor Q! 2 is turned off. And transistor Q. .

Q10 t Q10 operates similarly to the transistors Qsg to Qss constituting the output circuit 13, and the transistor Q111 is turned on.

! Also, by turning off transistor Q□, transistor Q! If all of Q8 to Q19 are off, these circuit operations can be ignored.

Regarding the output circuit 13, since the voltage Vc is at a high level, the transistor Q□ is turned off and the transistor Qjt is turned on. Therefore, transistor Q8. If none of ~Q0 is off, these circuit operations can be ignored.

On the other hand, when transistor Q0 operates in the on state, transistors Qaa, Q8? A base current is supplied to the circuits, causing them to operate in the on state. and transistor Q via transistor Q0. A base current is supplied to the transistor Ql18 t Qao, and the transistor Ql18 t Qao operates in an on state.

Note that the resistor R3fi supplies a bias voltage to the transistor Qao.

That is, during the interval 13 shown in FIG. 2, the transistor Q*s+Qas operates in the on state as described above, and the +
From the Vcc power supply, resistor R2m, transistor Qta,
@ Motor coil L, transistor Qsop Current ■2 flows through the ground line. The electric current 2 flows in the opposite direction to the electric current 11 as shown in FIG.

The motor is driven to rotate in a predetermined direction by the interlinkage between the magnetic flux generated from the motor coil L1 and the magnetic flux generated from the permanent magnet fixed to the rotor.

What should be noted here is the effect of the capacitors cA and cB connected between each input side and output side of the output circuit 12$13.

That is, if the output circuits 12 and 13e are viewed as amplifiers, it will be noticed that they constitute a Miller integrator by connecting the capacitors C and C.

In the Miller integrator, when the input current is i, the output voltage 'V6 changes at a voltage level determined by Vo='5idt=all. Therefore, capacitor C, CB
By selecting the capacitance of the output voltage V1. of the output circuit 12 when the level of the voltage VB v vc changes. changes smoothly as shown in FIG. 2(0), and the output voltage (13) of the output circuit 13 changes smoothly as shown in FIG. 2(g). If you do this, the output voltage L! *Vts
Zero cross position t,.

At t, the current 11yI! The switching is performed,
Furthermore, the current changes smoothly within a predetermined period of time, reducing the occurrence of the above-mentioned noise.

According to studies by the present inventors, when the input current is 1 mA or less, the above effects can be obtained by setting the capacitor CA Cn'k to a small capacity, for example, 0.01 μF.

Next, a method for detecting when the rotation of the motor is forcibly stopped due to an unexpected situation such as an article getting entangled in the fan will be described with reference to the circuit block 14.

The transistors Q41 + Q42 + Q43 are configured as a three-differential circuit, and the base of the transistor Q4+ is supplied with a voltage Y as a reference voltage. Constant current circuit cst, )7 resistor Q4B r Q46 t
Q47 is connected to the detection voltage v along with the resistors R, , *R42.
+s'tL2' is obtained from the voltage Vy and the above-mentioned detected voltage K'.

■12' is set as shown in FIG. 2 [F].

Looking at the relationship between the two, outside the period t, the voltage ■1□
', ■13' is Vy >VI2' +
Or Vy >Ls'.

Therefore, one of transistors Q42 + Q411 operates in an on state, and transistor Q411 operates in an on state. Transistors Q48 + Q49 constitute a current mirror circuit, so transistor Q4
The collector current of t is sucked into transistor Q49. Therefore, the transistor Qit is turned off, and the output current of the constant current circuit C84 is supplied as a base current to the bases of the transistors Qs2t Qns.

By operating the transistor Q52 in the on state,
Since the output current of the constant current circuit C86 does not flow to the ground line, the transistor QI+4 is turned off. In response, the transistor Qsa operates in an on state and discharges the electric charge stored in the capacitor C41 via the resistor R45k. At this time, by setting the resistance value of the resistor R43, the discharge time of the capacitor C41 can be delayed, resulting in characteristics as shown by the dotted line in FIG. 20.

On the other hand, period 1. At , voltage VY is at the lowest level, so transistor Q41 operates in the on state. In this case, transistor Q4. Since the transistor Q41 is off, the output current of the transistor Q41 is supplied to the transistors Q and I as the base current.

Then, transistor Qs+ is turned on9, transistor Q6! + Qsg is turned off. Constant current circuit C8
The output current of I+ is supplied to the transistor Q114 as a base current, and the output current of the constant current circuit C86 is supplied to the capacitor C41 as a charging current through the transistor Qetk.
supplied to As a result, the terminal voltage of the capacitor C64 is maintained at a substantially constant voltage level as shown by the dotted line in FIG. 2 (q) while the motor is making a predetermined rotation.

Therefore, if a pilot rung (not shown) is turned on by the above terminal voltage, it can be confirmed from the display that the motor is rotating normally.

On the other hand, when the motor stops rotating due to an unexpected situation, transistor Q4! Since either one of tQ411 continues to be on, the capacitor C4+ continues to be discharged by the above circuit operation. Then, the terminal voltage of the capacitor C41 decreases, the pilot lamp goes out, and it is possible to know that the rotation has stopped.

The method of using the terminal voltage of the capacitor C41 is as follows:
One example is described for convenience of explanation11), and the usage method is not limited to the above method.

According to the motor drive circuit to which the present invention is fully applied as described above,
It is possible to reduce the noise generated during phase switching, and also to reliably detect the sound of the motor stopping rotation.

〔effect〕

(1) By fully charging the capacitor during the phase switching time when energizing the motor coil, and discharging when the motor rotates to maintain the terminal voltage of the capacitor constant, whether or not the motor is rotating can be determined by the terminal voltage. can be easily detected.

Although the invention made by the present inventor has been specifically explained above based on examples, it goes without saying that the present invention is not limited to the first half examples, and can be modified in various ways without departing from the gist thereof. Nor.

For example, detection of motor stoppage may be performed using sound.

[Application field]

In the above description, the invention made by the present inventor has mainly been described with respect to a drive circuit for a flat plastic smoke, which is the field of application behind the invention, but the present invention is not limited thereto.

For example, it can be used to detect the stoppage of a spindle motor!
: Can be done.

It can also be used in various electronic devices such as VTRs, tape recorders, and record players.

[Brief explanation of the drawing]

FIG. 1 shows a circuit diagram showing an embodiment of a motor drive circuit to which the present invention is applied, and FIG. A waveform diagram is shown for explaining. 1... Hall element, 11... amplifier, 12.13.
... Output circuit, 14... Motor stop detection circuit, Ll.
...Motor coil, L, L...Current, vA...Rotation position detection signal, VB t Vc t Vx * Vy-
1-Voltage, Vl, , V,. ...output voltage, vl,',v,,'...rotation detection voltage, C81~CSa...constant current circuit, CAICB
IC41...Capacitor, Q1-Q54...Transistor, R8-R26...-c, [-

Claims (1)

[Claims] 1. A comparison circuit that compares the reference voltage with the output voltages of multiple output circuits that supply current to the motor coil, and a first output voltage of the comparison circuit that is applied to the capacitor at the time of phase switching when supplying current to the motor coil. charge the battery,
The switch circuit includes a switch circuit that discharges a capacitor using a second output voltage at times other than phase switching, and a capacitor that maintains a predetermined terminal voltage when the motor is rotating by charging and discharging. A motor drive circuit characterized by being configured to detect presence or absence.